"uuid","repository link","title","author","contributor","publication year","abstract","subject topic","language","publication type","publisher","isbn","issn","patent","patent status","bibliographic note","access restriction","embargo date","faculty","department","research group","programme","project","coordinates"
"uuid:d61333e4-8450-4b52-b15c-bd38b3ad1673","http://resolver.tudelft.nl/uuid:d61333e4-8450-4b52-b15c-bd38b3ad1673","Design and Structural Analysis of the Propellant Tank for a Water Resistojet","Granero, I.","Cervone, A. (mentor)","2015","The purpose of this Thesis is to develop the design process of the pressurised propellant tank for a water resistojet, applicable to nanosatellite missions. The motivation of this system is its use on the CubeSat mission DelFFi, from the Technical University of Delft. The need for a small-sized pressure vessel is covered by the Detail Design delivered in this Thesis, which is a result of the application of decision making techniques as well as a structural analysis. It is possible to distinguish two ?elds of investigation throughout the work: design and structures. The design of the propellant tank is tackled following the Design Trades: a systems engineering approach which makes use of decision making, a trade-off process and uncertainty analysis. By applying a 10-step methodology, a set of conceptual designs is developed and further re?ned into a preliminary design. As far as the structural analysis is concerned, both an analytical study and a Finite Element Analysis are completed. The former is mainly used for veri?cation and validation of the latter. The result is a Detail Design, ready for manufactureandtesting. As a result, a design compliant with the requirements is delivered, together with CAD and Finite Element models. This design involves a rectangular section pressurised tank, compatible with CubeSat structures, manufactured from aluminium via CNC milling. The conclusion is a successful application of the methodologies, a complex design and guidelines with expected correct performance and a know how on pressurised propellant tank design and analysis.","space propulsion; CubeSat; DelFFi; propellant tank; design trades; finite elements; FEA; systems engineering","en","bachelor thesis","","","","","","","","","Aerospace Engineering","Space Systems Engineering","","","",""
"uuid:9633fb1c-9927-426d-a784-0c5f3ff36e6f","http://resolver.tudelft.nl/uuid:9633fb1c-9927-426d-a784-0c5f3ff36e6f","Conceptual Design and Simulation of a Microturbine: An Electric Car Range Extender Application","Head, A.J.","Visser, W.P.J. (mentor); Mee, D.J. (mentor); Van Buijtenen, J.P. (mentor); Rao, A.G. (mentor)","2011","The microturbine seems to be a viable option for implementation into Hybrid Electric Vehicle (HEV) systems. A microturbine was constructed in the Gas Turbine Simulation software GSP in order to assess its viability for a low-power range extender. Due to the small magnitude of the turbine, scale effects need to be incorporated into the performance models. A microturbine has various advantages over other heat engines (Wankel, Piston, or Fuel Cell), and the capabilities in terms of range extension of the HEV are potentially superior. Through the use of the Engineering Design Process, a new microturbine design was developed that allows the system to be implemented into the HEV system. Aspects such as geometric size, weight, cost, availability, and ease of production were used to compare the different concepts and determine their feasibility. Empirical loss models previously researched were adapted and implemented into scheduling components of the microturbine base model. The model was used to simulate the required output data (Mechanical/ Electric Power, CO_2 emissions, Fuel flow rate, Exhaust gas temperature and Exhaust gas mass flow) for a range of predefined design powers (9, 15, 22, 30, 36 kW). Power-to-weight ratios and component dimensions were also calculated and sent for analysis. The data above was generated under two control schemes (fixed and variable speed) and at three power codes; maximum power (100%), part load (60%) and idle (20%). The HEV model used this data to configure and size its own system. Simulations of design and optimization are important as it restricts the size of the HEV. The results suggest that the variable speed control scheme will extend the life of the system and reduce emissions substantially. If the microturbine is operated at or below ISA conditions the scheme offers numerous other advantages. However the control system is far more complex and will cost more to develop. Recommendations have been highlighted for model configuration improvement and focus on the control system is important for continued programme development.","Microturbines; Hybrid Electric Vehicles; Fuel Analysis; Performance","en","bachelor thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","Flight Performance and Propulsion","",""
"uuid:c8807f83-8d00-4aeb-a273-617f9834881a","http://resolver.tudelft.nl/uuid:c8807f83-8d00-4aeb-a273-617f9834881a","Advanced Nano Telescope: A cornerstone solution in Earth Observation","Van de Bos, M.F.; Bijster, R.J.F.; Dolkens, D.; Mathis, C.; Peters, R.B.M.; Rotthier, L.B.M.; Schoemaker, R.F.M.; Sikkel, L.N.C.; Van de Wetering, R.","Kuiper, J.M. (mentor); Visser, P.N.A.M. (mentor); Wu, X. (mentor)","2011","Recent developments in satellite industry gaining strong attention are so called nanosatellites. These small satellites, with sizes of about a milk carton, are easy to build and much more adordable, promising great advantages for future space missions. Up until today no reliable mid-resolution Earth observation instrument has been build that can be operated on such a small, low cost satellite. In light of these events this years Design Synthesis Exercise group 9 developed such a camera system which is called the Advanced Nano Telescope (ANT) providing a novel instrument that can be carried as payload by nanosatellites. The novelty lies in the applied principles of miniaturization and intelligent distribution in order to compete with a single large scale instrument. The strength of the instrument developed lies in the fact that it can take images with 7.5 meter resolution, requiring a volume of only 10 x 10 x 15 cm at an estimated cost about EUR 100,000. The small dimensions allow it to ft into half a standard 3 unit CubeSat such as the Delfi-n3Xt. The resolution is achieved by limiting the system to sense a narrow band around a single color, making use of a well designed combination of lenses and mirrors folding the light path enabling a long focal length. The thermo-mechanical design is designed such that the instrument functions in the hostile space environment from altitudes of 540 to 1440 km altitude. ANT has a smart modular structure that allows a mission designer to simply purchase the instrument and plug it into a satellite. Since all required electronic components are already present in the instrument the host satellite only needs to provide power and pointing capability to be able to achieve a fully functional system. One ANT by itself can take mid-resolution mono-chromatic images, but its real value will show when it is launched in a constellation, something which the low cost per unit allows. Multiple constellations of ANT's can outperform single satellites systems with similar ground resolutions in terms of development time, construction costs, operating costs and revisit time, enabling color composite imagery and promising improved availability at a lower price per image. Furthermore dedicated relay satellites can be added to achieve higher data rates. Overall catastrophic failures are eliminated as multiple satellites performing independent tasks are present offering redundancy and the possibility of replacement. The conclusion is that the system developed holds a promising future with a wide range of possible applications. The instrument itself is striking due to its apparently simple but intelligent and robust design enabling Earth observation without the need of expensive large scale satellites. For future work it is recommended to further develop the concept in order to prototype and test the actual performance of the ANT instrument.","telescope; miniaturization; nano; mono-chromatic; satellite; nanosatellite","en","bachelor thesis","","","","","","","","2014-02-06","Aerospace Engineering","Space Engineering","","Bachelor Aerospace Engineering","",""
"uuid:9090f24a-dff0-4deb-9bbc-ea4b5cb52527","http://resolver.tudelft.nl/uuid:9090f24a-dff0-4deb-9bbc-ea4b5cb52527","Heliport Gorinchem - Designing an Aerial Logistic Network","Ceulemans, B.; Cohen, J.B.; Van Grootheest, H.A.; Helmijr, M.S.D.; Kardzha, I.; Kuipéri, F.T.; Munatsi, P.; Repko, M.G.J.; Schot, C.E.; Vermeersch, W.J.A.","Stoop, J.A.A.M. (mentor); Brügemann, V.P. (mentor); Sundaramoorthy, P.P. (mentor)","2013","The Dutch city of Gorinchem has great economic growth opportunities for the future, but is limited by its transport system. It is strategically located at a crossroad of two motorways and two rivers, the Boven-Merwede and the Linge. Gorinchem is home to a number of multinationals, among others Damen Shipyards and Van Oord. This sets the right conditions for economic growth. However, the city roads are congested and the limited accessibility of the area by train and car slows this economic growth. Therefore, a solution is required to make Gorinchem more accessible. The development of an aerial network is an approach that could comply with the vision of the city as an innovative regional business centre. This project, called Heliport Gorinchem, aims to provide a final design for an aerial logistic network that can be implemented in Gorinchem in the year 2020. The project consists of three main parts: the project initiation and definition, a conceptual design part, and a detailed design part. This report contains a review of the project initiation and definition, and the conceptual design part. The main focus of this report is on the detailed design part of the project. The aim of the project initiation and definition is to structure the project, come up with a time management plan and organise the group. Also, the requirements and constraints for the project are set. The goal of the project is to design a concept for a sustainable logistic network of multi-purpose aerial vehicles in Gorinchem, competitive with the current transport market, within ten weeks. A market analysis is performed after the project initiation, to identify the traffic problem in Gorinchem on a local and regional scale. Locally, the city has three connection points to the motorways and these points form the entry and exit of the city. The capacity of the roads to these points is too low for the traffic they have to handle. It is estimated that there is an overload of 4000 travellers per hour during rush hours. On a regional level, a connection with a railway to the north and south of the country fails to appear and there is no aerodrome near Gorinchem to have any connection by air. The outcome of the conceptual design part is a concept for an operational aerial network. To come up with ideas for possible concepts for the network, multiple brainstorm sessions are held. A selection procedure is executed in order to reduce the amount of possible concepts and to come up with a final concept for the detailed design part of the project. From this, a combination of a linear local and a linear regional network is selected. The verification of the conceptual design has led to the conclusion that an aerial network alone will not solve the traffic problem entirely at this moment. However, there is a demand for a better accessibility and economic growth in of the city. Therefore the aim of the project is altered into a new vision. The goal of the aerial network is to serve economic growth of the city. An aerial network will allow Gorinchem to improve its accessibility to important locations, while becoming an important link in the aerial infrastructure of the Netherlands. The aim is therefore to implement an aerial network before 2020. In the short term, up to 2030, the goal is to realise a profitable aerial network. In the years thereafter an expansion of the aerial network will allow for an improvement of the traffic situation in Gorinchem. This is the aim of the long-term vision. The detailed design part elaborates on the design of all aspects of the aerial network in the short term, while keeping its long-term development in mind. The main customers are identified to be business travellers. Other smaller markets are determined as well, like tourism, medical assistance and governmental flights. The aerial vehicle for the short term is selected to be an Eurocopter EC135 helicopter that makes use of a hybrid engine and noise reducing technology. The helicopter should operate under visual flight rules to limit the investment costs. The aerodrome is designed to be a self-sustaining heliport with a low investment cost of 750,000 euro for the landing site. For the location, the industrial estate Avelingen at the edge of the suburbs is chosen. It has a direct connection with the motorway and can be linked with the future railway from Breda to Utrecht. Furthermore, it is located at the Boven-Merwede river which has an extra advantage. An approach route for helicopters will minimise the environmental impact regarding noise and safety. A business model for the aerial network has been developed and analysed. Unfortunately, the business model shows that it will not be profitable in the short term to set up a transport service for business travellers. The main reasons for this are the high maintenance costs of the vehicle, call out costs, and airport charges. From the conducted research, it can be concluded that it is possible to realise a heliport in Gorinchem and start its operations in the year 2020. Although the implementation of a profitable aerial network seems currently not feasible, it is reasonable to invest in the construction of a heliport as there is demand for a heliport in Gorinchem. It is advised to develop a heliport that allows companies like Damen Shipyards and Van Oord to use the facilities with their own helicopter. Furthermore, this will be a first and innovative step in the development of a regional aerial network, which provides fast and high quality transport. This can offer Gorinchem the opportunity to take a leading role in aerial transportation on a regional scale in the Netherlands . Furthermore, it will support the economic growth of the city. Further research should focus on the design of a new aerial vehicle. It is recommended that maintenance and fuel cost are reduced for the new aerial vehicle in order to make the aerial network profitable. Other research should focus on the expansion of the aerial network and find alternative locations with low landing charges. In this way, the high landing fees at the airports can be avoided and the possibility to make a profitable aerial network will increase. It is recommended to perform a market analysis on the willingness to pay of the future business travellers and other markets. This will have influence on the income of the business model. In the best case scenario, the design can even become profitable in the short term.","Design Synthesis Exercise; Aerial logistic network; Heliport","en","bachelor thesis","","","","","","","","","Aerospace Engineering","Air Transport and Operations","","","",""
"uuid:b4019f6f-35ab-4db8-a65b-14493d26d448","http://resolver.tudelft.nl/uuid:b4019f6f-35ab-4db8-a65b-14493d26d448","Formation Flying","Bos, D.A.; Dijkers, H.P.A.; Gutleb, T.L.M.; Herinckx, L.E.; Van Nunen, R.; Radfar, H.; Van Rompuy, E.; Sahin, S.E.; De Wit, J.","Beelaerts van Blokland, W.W.A. (mentor); Roling, P. (mentor); Giorgi, G. (mentor); Verhgen, W.J.C. (mentor)","2011","A first outline for the concept of formation flying is investigated. The objective is to create a sustainable air transportation system for the next generation of aircraft from a formation flying perspective. When flying in formation over long distances the trailing aircraft can benefit from the wake vortices created by the preceding aircraft. Aircraft flying in formation can reduce their fuel consumption substantially by benefitting from wake vortices. Consequently, the emission of carbon dioxide is significantly reduced. The four main areas of investigation are aerodynamics, air traffic operations, aircraft design and navigation. Additionally, the technical design development and requirements are described.","Formation; Innovative; future; fuel reduction","en","bachelor thesis","","","","","","","","","Aerospace Engineering","Air Transport & Operations","","","",""
"uuid:78c7a47c-ca10-420d-9ab3-cf63f95183e2","http://resolver.tudelft.nl/uuid:78c7a47c-ca10-420d-9ab3-cf63f95183e2","A preliminary evaluation of the B2000 nonlinear shell element Q8N.SM","Wohlever, C.","","1998","Over the past ten years, there has been a growing interest within the mechanics community towards the application of group theoretic methods to aid in the global buckling analysis of symmetric-free structures. Within the context of a numerical arclength continuation procedure, group theory helps one systematically find an ""optimal"" set of basic vectors which reflect the symmetry of a given problem. The immediate payoff in formulating the numerical procedure with respect to the symmetry-adapted basis is a global de-coupling of the equilibrium equations which in turn leads to: (1) a dimensional reduction in the problem size; (2) improved numerical conditioning while computing solutions in the vicinity of singular points; (3) a systematic method for detecting and diagnosing for symmetry-breaking bifurcations. In this book, a new group theoretic nonlinear continuation algorithm, written for the modular finite element package B2000, will be discussed. The focus of the work was to provide a general computational environment in which a wide range of symmetric problems for structural mechanics could be formulated and solved. A group theoretic approach allows the computation of equilibrium solutions for perfect structures which might otherwise be numerically intracebie. Furthermore, understanding the global behaviour of the perfect structure can be crucial to understanding the behavior of the imperfect structure. Numerical examples to be presented include results from the buckling analysis of a flat plate and an axially compressed cylindrical shell.","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3784a5b8-b238-4cc9-ab75-ae91982710ca","http://resolver.tudelft.nl/uuid:3784a5b8-b238-4cc9-ab75-ae91982710ca","DEOS Progress Letter","Klees, R.","","1998","","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c7e574ee-ae5a-40e0-b8a9-f15f40d55680","http://resolver.tudelft.nl/uuid:c7e574ee-ae5a-40e0-b8a9-f15f40d55680","Aircraft design and analysis systems (ADAC)","Bill, C.; Van Dalen, F.; Rothwell, A.","","1997","","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e3108e2d-0708-46e9-bdc1-17a5e44cf224","http://resolver.tudelft.nl/uuid:e3108e2d-0708-46e9-bdc1-17a5e44cf224","CleanEra: A Collection of Research Projects for Sustainable Aviation","Droste, B.; Van Gent, R.; Straathof, M.; Steenhuizen, D.; Kotsonis, M.; Geuskens, F.; Shroff, S.; Guerriero, G.; Gangoli Rao, A.; Lada, C.; Dewanji, D.; Yu, H.; Schroijen, M.; Hoekstra, J.; The CleanEra Team ","","2015","The CleanEra project was initiated with the goal of developing revolutionary ideas for civil aviation. These ideas were to offer solutions which would limit and reduce some of the negative aspects of aviation, namely: emissions and the use of resources. This book presents you with the highlights of this journey in search of new technologies for a revolutionary aircraft; an aircraft that not only offers a future of comfortable air travel for the passenger, but a future of sustainable aviation for the planet as well.","The CleanEra Project; OA-Fund TU Delft","en","book","IOS Press","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:8a4ebd0a-5a15-49f5-aab9-9cb3da3fd5bc","http://resolver.tudelft.nl/uuid:8a4ebd0a-5a15-49f5-aab9-9cb3da3fd5bc","Overview of stability and transition in external aerodynamics","Henkes, R.A.W.M.; Van Ingen, J.L.","","1998","The boundary layer along the fuselage, wings and tailplanes of aircraft will usually be laminar at the leading edge and will become unstable further downstream. Once the boundary layer has become unstable it will undergo transition to turbulence. Stability and transition can be considered as one of the most complex problems of fluid dynamics. The details depend on a number of parameters, such as the type of initial perturbations (e.g. free-stream turbulence level, wall roughness), Reynolds number, streamwise pressure gradient, and wall curvature. This report gives an overview of existing theory to compute and analyse stability and transition of boundary layers. It covers the classical linear stability theory up to recent developments, such as the Parabolized Stability equations.","aerodynamics; gas boundary-layer flow","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:69feb29d-4225-4923-a240-2186be9d961e","http://resolver.tudelft.nl/uuid:69feb29d-4225-4923-a240-2186be9d961e","Aviobrug tussen luchthaven en luchtvaartmaatschappij","Vlot, A.","","2001","De ontwikkeling vande Aviobruggen voor Schiphol, 1958-1971, geschiedenis van het bedrijf Aviobridge en de relatie met Aviolanda en Fokker enerzijds en KLM anderzijds","Aviobridge; Aviolanda; Fokker; KLM","nl","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:772d751a-896b-4db0-b9b6-ccdfbfac1cd7","http://resolver.tudelft.nl/uuid:772d751a-896b-4db0-b9b6-ccdfbfac1cd7","Design of a Michelson Interferometer for Quantitative Refraction Index Profile Measurements","Nijholt, J.L.M.","","1998","This book describes the theoretical design of a three camera Michelson interferometer set-up for quantitative refractive index measuerments. Although a two camera system is easier to align and less expensive, a three camera interferometer is preferred because the expected measuring accuracy is much better. Here analytical expressions are found for the calculation of the required alignment accuracy of the interferometer's components: three CCD-cameras (six degrees of freedom each), a quarter wave plate (one degree of freedom) and a polariser (one degree of freedom). Also the required accuracy in the normalization of the intensity levels on the CCD-cameras is calculated.","interferometry; multy camera interferometer; positioning accuracy","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1a2a249b-80fe-4360-bbbc-689b6cc735cd","http://resolver.tudelft.nl/uuid:1a2a249b-80fe-4360-bbbc-689b6cc735cd","Prediction of bypass transition with differential Reynolds stress models","Westin, K.J.A.; Henkes, R.A.W.M.","","1998","Boundary layer transition induced by high levels of free stream turbulence (FSl), so called bypass transition, can not be predicted with conventional stability calculations (e.g. the en-method). The use of turbulence models for transition prediction has shown some success for this type of flows, and the present study is a further investigation on the use of low-Reynolds number, single-point closures for transition prediction. The work is focused on two differential Reynolds Stress Models (DSM), which are compared with the in previous studies more elaborately tested two-equation model by Launder Sharma. The results obtained with the DSM are relatively promising in some test cases, with a qualitatively correct description of the different normal stresses throughout the computational domain. However, the applicability of the models is very limited if a wider range of test cases are considered. Although the Differential Reynolds Stress Models have better prospects to describe the very anisotropic fluctuations that are observed in transitional boundary layers, the overall predictions of the location of the transition region are worse than obtained with the two-equation model. Detailed comparisons with results from Large Eddy Simulations have revealed significant shortcomings in the modelling of the dissipation. The DSM suffer from a large overprediction of the dissipation in the pre-transitional boundary layer, which also affects the modelling of the pressure strain terms. The present study also shows that some of the results reported in the literature may be too optimistic, since they seem to be affected by the implementation of the free stream boundary conditions. The predictions are sensitive to the FST-level in the vicinity of the boundary layer edge, and large variations in the predicted transition location can be obtained depending on how the free stream boundary is treated. The outcome of the present study indicates that, if single-point closures are going to be considered as a realistic transition prediction tool for industrial applications, some major improvements in the modelling are necessary.","turbulence; turbulent flow; gas boundary-layer flow","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:bcbced74-506b-450f-858a-3a200144eca6","http://resolver.tudelft.nl/uuid:bcbced74-506b-450f-858a-3a200144eca6","Definition, transformation-formulae and measurements of tipvane angles","Bruining, A.","","1987","Carried out within the Dutch Development Program for Wind Energy (NOW-2); by order of the Management Office for Energy Research PEO; financed by the Ministry of Economie Affairs.","wind turbines; aerodynamics","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:58fb31f8-2257-4af4-ba70-160fc2c32f6c","http://resolver.tudelft.nl/uuid:58fb31f8-2257-4af4-ba70-160fc2c32f6c","Base flow and exhaust plume interaction. Part 2: Computational study","Schoones, M.M.J.; Houtman, E.M.","","1998","A computational study of the flow field along an axi-symmetric body with a single operating exhaust nozzle has been performed in the scope of an investigation on base flow-jet plume interactions. Results of a single nozzle plume with a high supersonic exit Mach number of 4 exhausting in co-flowing supersonic free stream of Mach 2.98 are presented for a number of jet stagnation pressure to freestream static pressure ratios, ranging from Ptj/Poo = 600 to no-jet flow at Mach 2.98. These conditions were used to validate the numerical Euler and Navier-Stokes Simulations with experimentally obtained data [4, 14]. Euler and Navier-Stokes simulations have been made in combination with regular meshes. In order to obtain a better physical representation of the interaction zone mesh adaptation has been applied for a Navier-Stokes simulation. One-dimensional adaptation to the Mach number distribution has been applied along fixed lines in the radial direction. In this way the flow field could be accurately portrayed. The three numerical simulation techniques are compared using flooded Mach-number contour plots. The Navier-Stokes simulation with Mach-adapted mesh provided the basis tor comparison with experimental results. A physical description of the flow field in the base region, or cavity, is presented using streamlines. Reattachment of the flow to the base of the model, which results in heat-transfer to the surface, has been found to be possible at approximately 45% to 50% of the base radius, measured from the centerline. However, reattachment has not been accurately visualized. Base pressure distributions obtained through all three different types of numerical simulation are presented in order to compare to the experimental data. No proper reproduction of the experimental Pb/Poo - Ptj/Poo curve (see [4, 14] could be attained.","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1aeca382-77f0-4852-9414-1d84b3e6a498","http://resolver.tudelft.nl/uuid:1aeca382-77f0-4852-9414-1d84b3e6a498","A numerical formulation for moisture migration in masonry","Van Zijl, G.P.A.G.","","1999","The moisture content and migration in cementitious materials determine its time dependent response. Much research has been do ne over the last decades to gain insight in these phenomena and to distinguish between true and apparent mechanisms of creep and shrinkage. However, experimentally as well as computationally much remains to be done to characterise the indentified role players, for instance, true material shrinkage, stress-induced shrinkage, basic creep and the coupled effect of cracking and accelerated moisture migration. This contribution addresses these issues. A numerical model for the finite element analysis of creep, shrinkage and cracking in cementitious materials has been described in an accompanying report (Van Zijl 1999). Here, a model is elaborated tor analysing the moisture migration, the underlying mechanism of shrinkage and creep. The coupling with the mechanical analysis is also described. The material of interest is masonry, to be regarded as a particular cementitious concretelike material. Existing experimental data on masonry is employed tor the model parameter estimation and the validation. However, the experiments were not devised to distinguish between the different phenomena included in the numerical model. This excludes the possibility of the estimation of parameters even by an inverse approach. For this reason an experimental program is proposed with specific tests on small specimens for determining the model parameters and separate tests of wall parts on the meso-scale tor the validation of the model.","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:17ddd09b-8d0a-453c-ac79-35b9d16900a0","http://resolver.tudelft.nl/uuid:17ddd09b-8d0a-453c-ac79-35b9d16900a0","Delft Aerospace Design Projects 2006: Design in aeronautics, astronautics, earth observation and related areas","Melkert, J.A.","Bruggeman, V. (contributor); van Brummelen, H. (contributor); Joosten, P. (contributor); Saunders-Smits, G.N. (contributor); Zandbergen, B.T.C. (contributor); Melkert, J.A. (contributor)","2006","","Design synthesis exercise","en","book","B.V. Uitgeversbedrijf Het Goede Boek","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a49fbb82-97df-4826-a859-0b9f5d43faef","http://resolver.tudelft.nl/uuid:a49fbb82-97df-4826-a859-0b9f5d43faef","Optimum cruise performance of subsonic transport aircraft","Torenbeek, E.","","1998","","aircraft performance; aircraft control; flight simulation","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b6156ad4-9b56-463a-a82a-ec11fa70cbcc","http://resolver.tudelft.nl/uuid:b6156ad4-9b56-463a-a82a-ec11fa70cbcc","Review and selection of methods for structural reliability analysis","Van Eekelen, A.J.","","1997","To select a method for analyzing structural reliability problems, including pptimization under reliability constraints, a literature survey was performed. In this review the most frequently used and most generally applicable methods are described. An extensive list of references is included. The methods described here are compared on the basis of available information in the literature, and not on experience gained with these methods. The criteria for comparison are: - numerical efficiency - accuracy - general applicability For structural optimization under reliability constraints numerical efficiency is especially important. This is because multiple so-called limit states generally have to be evaluated at each analysis step. The method that looks most promising with respect to the above criteria is the Galerkin based response surface method. It is both efficient, due to the explicit nature of the response surface, and accurate due to the rigorous mathematical basis. Finally, an example of a beam with random flexural rigidity is analyzed using this method. Although no structural optimization is done in this example, the choice of method seems justified.","mechanics of engineering structures","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7df59b79-2c6b-4e30-bd58-8454f493bb09","http://resolver.tudelft.nl/uuid:7df59b79-2c6b-4e30-bd58-8454f493bb09","The International Airborne Wind Energy Conference 2015: Book of abstracts","Schmehl, R.","","2015","Airborne wind energy is an emerging field in the renewable energy technologies that aims to replace the use of fossil fuels for energy production on an economical basis. A characteristic feature of the various concepts that are currently pursued is the use of tethered flying devices to access wind energy at higher altitudes where the wind is more consistent. This booklet contains 70 abstracts that were presented at the Airborne Wind Energy Conference 2015 (AWEC 2015), which was held from 15-16 June 2915 at Delft University of Technology. Further included are 37 additional full page photos and illustrations, mainly of prototypes characterising the state of airborne wind energy technology in 2015.","Airborne Wind Energy; Kite Power; AWEC 2015; Airborne Wind Energy Conference; Makani; EnerKite; Ampyx; TwingTec; eKite; TU Delft; enevate; Google; AWESCO","en","book","","","","","","","","2015-06-22","Aerospace Engineering","Wind Energy","","","",""
"uuid:22086524-00ca-4bed-9b12-b312dd2f6345","http://resolver.tudelft.nl/uuid:22086524-00ca-4bed-9b12-b312dd2f6345","Residual strength of cracked 7075 T6 Al-alloy sheets under high loading rates","Vasek, A.; Schijve, J.","","1997","","aluminiumlegeringen; breukmechanica","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4e292bd1-bd9d-4e7e-ae09-90e953f75acf","http://resolver.tudelft.nl/uuid:4e292bd1-bd9d-4e7e-ae09-90e953f75acf","Boundary-Layer Separation in Aircraft Aerodynamics: Dedicated to Professor J .L. van Ingen","Henkes, R.A.W.M.; Bakker, R.G.","","1997","","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:deeef14f-9dd5-4ca3-bea4-70d442925645","http://resolver.tudelft.nl/uuid:deeef14f-9dd5-4ca3-bea4-70d442925645","Image analysis as measuring technique in flows: Invited Lectures and Extended Abstracts of the Euromech Colloquium 279","Nieuwstadt, F.T.M.; Riethmuller, M.L.","","1991","","Particle Image Velocimetry; Measuring technique; PIV methods; techniques and application; PIV and particle tracking; techniques and application; Scalar fields and data analysis; Holographic techniques.","en","book","J.M. Burgers Centre, Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:74b2d97e-1ccf-412f-a545-6183bc58e9a1","http://resolver.tudelft.nl/uuid:74b2d97e-1ccf-412f-a545-6183bc58e9a1","Air Transport and Operations. Proceedings of the Third International Air Transport and Operations Symposium 2012","Curran, R.; Fischer, L.; Pérez, D.; Klein, K.; Hoekstra, J.; Roling, P.; Verhagen, W.J.C.","","2012","Air transport must evolve if it is to optimize its value in the 21st century. The mood in the aerospace industry is positive with regard to economic recovery, but the focus in this transitional time must be on sustaining value, without losing sight of environmental and safety priorities","","en","book","IOS Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e4378fce-7225-4bb7-ba90-6268def61d00","http://resolver.tudelft.nl/uuid:e4378fce-7225-4bb7-ba90-6268def61d00","A review of propeller modelling techniques based on Euler methods","Zondervan, G.J.D.","","1998","Future generation civil aircraft will be powered by new, highly efficient propeller propulsion systems. New, advanced design tools like Euler methods will be needed in the design process of these aircraft. This report describes the application of Euler methods to the modelling of flowfields generated by propellers. An introduction is given in the general layout of propellers and the propeller slipstream. It is argued that Euler methods can treat a wider range of flow conditions than the classical propeller theories. The power of Euler methods lies in the fact a separate wake model is not needed because their solution includes the propeller slipstream. Two different ways are described of modelling the propeller slipstream using Euler methods. These are the time-accurate approach that uses the real propeller geometry and the time-averaged approach using an actuator disc representation of the propeller. Both techniques and their specifics concerning the grid and the boundary conditions that have to be imposed are described. The results of a few propeller calculations using Euler methods are described. Discrepancies between experiments and the simulations can of ten be traced back to the neglect of the physical viscosity and the quality of the grid. Research is still ongoing into further improving the mathematical flow models and using new concepts like grid adaption.","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c8667f42-b701-468c-8c90-a110004a704f","http://resolver.tudelft.nl/uuid:c8667f42-b701-468c-8c90-a110004a704f","Prediction of mean flow data for adiabatic 2-D compressible turbulent boundary layers","Motallebi, F.","","1997","This book presents a method for the prediction of mean flow data (i.e. skin friction, velocity profile and shape parameter) for adiabatic two-dimensional compressible turbulent boundary layers at zero pressure gradient. The transformed law of the wall, law of the lake, the van Driest model for the complete inner region and a correlation between the Reynolds number based on the boundary layer integral length scale and the Reynolds number based on the boundary layer momentum thickness were used to predict the mean flow quantities. The results for skin friction coefficient show good agreement with a number of existing theories including the van Driest II and the Huang et al. Comparison with a large number of experimental data suggests that at least for transonic and supersonic flows, the velocity profile as described by van Driest and Coles is Reynolds number dependent and should not be presumed universal. Extra information or perhaps a betler physical approach to the formulation of the mean structure of compressible turbulent boundary layers even in zero pressure gradient and adiabatic condition, is required in order to achieve complete (physical and mathematical) convergence wh en it is applied in any prediction methods.","transonic aerodynamics; supersonic aerodynamics; gas boundary-layer flow; gas flow past obstacles","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:de43c550-f438-46dd-b0c6-b8364138b8d0","http://resolver.tudelft.nl/uuid:de43c550-f438-46dd-b0c6-b8364138b8d0","Linear quadratic regulator design for an unpowered, winged re-entry vehicle","Mooij, E.","","1998","This report describes the design of an attitude controller for an unpowered, winged re-entry vehicle. The decoupling of the symmetric and asymmetric motion makes it possible to design two separate controllers, one for the pitch mot ion and one for the lateral motion. The design of the controller, a Linear Quadratic Regulator, is based on linearisation of the equations of motion and feedback of the attitude and angular rates. The gains appearing in the control laws are computed by defining quadratic cost criterion and then solving the matrix Riccati equation. Results of the study include the step and ramp response of the two separate controllers and the flight along the nominal trajectory with the integrated controller. The deviations from the nominal trajectory are acceptable, so this controller can be used for a detailed sensitivity analysis.","spaceflight dynamics; orbit computations; spacecraft control","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f3534d8e-3f2a-4afe-ae1f-c48f72c9ca3a","http://resolver.tudelft.nl/uuid:f3534d8e-3f2a-4afe-ae1f-c48f72c9ca3a","Overview of turbulence models for external aerodynamics","Henkes, R.A.W.M.","","1998","An overview is given on the background of different turbulence models that can be used to compute boundary layers in external aerodynamics, such as for aircraft. The overview includes algebraic models (Cebeci-Smith, Baldwin-Lomax), a half-equation model (Johnson-King), two-equation models ( K-E-K-), and a differential Reynolds-stress model. The models were compared for boundary layer without and with streamwise pressure gradient. The models were also used to study the large-Reynolds number scalings (wall function and defect layer). The comparisson of models and the sealing analysis are described in three seperate journal contributions.","turbulence; turbulent flow; aerodynamics","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:53b51fcf-c876-464e-9997-8e06e6d46a99","http://resolver.tudelft.nl/uuid:53b51fcf-c876-464e-9997-8e06e6d46a99","Fatigue Specimens for Sheet and Plate Material","Schijve, J.","","1998","The usefulness of simple sheet and plate specimens is discussed for various experimental research purposes. Specimens should be representative as much as possible for the conditions of fatigue problems in practice, which is more difficult to achieve for the fatigue crack initiation phase than for macro-crack growth. In many cases small specimens can not be recommended because of insufficient similarity to the conditions of the engineering structure. Larger specimens have advantages for measurements of crack length and crack closure. The compact tension specimen and a recently proposed derivative are asymmetric specimens, while the middle crack specimen, the central notch specimen and the double-edge notch specimen are symmetric. The latter specimens should be preferred for experimental reasons as well as for reasons of a better similarity to the conditions of practical fatigue problems. A significant disadvantage of the asymmetric specimens is the high gradient of the stress intensity factor (dK/da).","","nl","book","Delft University Pre ss","","","","","","","","Aerospace Engineering","","","","",""
"uuid:713d5d9e-4643-43b6-8b51-07749417634d","http://resolver.tudelft.nl/uuid:713d5d9e-4643-43b6-8b51-07749417634d","A system look at electromechanical actuation for primary flight control","Lomonova, E.A.","","1997","An overview is presented of the emergence of the ALL Electric flight control system (FCS) or power-by-wire (PBW) concept. The concept of fly-by-power refers to the actuator using electrical rather than hydraulic power. The development of the primary flight control Electromechanical Actuators (EMAs) is one of the essential steps in the implementation of the ALL Electric Aircraft. There is a great deal of interest in the application of brushless motors (BM) with rare-earth magnet rotors using external commutation as EMAs flight control systems. The increased complexity of the converter is caused by the fact that thyristor inverters with forced commutation involve additional components and a more complicated mechanical design but a simple control structure, the BM machine must be fed with alternating currents of variabie amplitude, frequency and phase. It is for these reasons that no standard solution for the control of brushless motors has emerged as in the case of the DC motor. The purpose of this book is to present a theoretical investigation of EMAs based on the BM description: electromechanical architecture, magnet materials, operating principles, electromagnetic processes, etc. In order to design current, position, torque, and speed controllers for BM, the general theory of electromechanical and electromagnetic processes in electrical machines in electrical and power converters is used. This book describes a basic approach to the creation of mathematical models for BM with rectangular and sinusoidal current waves. It presents the hardware for position, torque, and current control systems for EMAs. This work also treats the analysis and synthesis of different aircraft power systems with EMAs. Finally, the basic approach for the preliminary design of EMAs is presented.","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ea9ba01c-e184-4140-98c8-38980160de31","http://resolver.tudelft.nl/uuid:ea9ba01c-e184-4140-98c8-38980160de31","DEOS Progress Letter","Klees, R.","","1998","","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d8642115-5dc3-4e6e-a4c5-adc5a59ba37e","http://resolver.tudelft.nl/uuid:d8642115-5dc3-4e6e-a4c5-adc5a59ba37e","Orientation on quantitative IR-thermografy in wall-shear stress measurements","Mayer, R.","","1998","Wall-shear stresses are highly important in the aerodynamic design of aircraft, because they determine the drag and thus the fuel consumption of an airplane. Due to this importance many different measurement techniques have been developed. Most of these techniques are intrusive, which means that the flow is disturbed by the presence of a measurement probe. The hot film technique is non-intrusive, because hot films measure the heat transfer from an electrically heated surface of an object to the flow, which is related to the wall-shear stress. Using the theory of the hot film technique, we have developed a new non-intrusive wall-shear stress measurement technique, which is based on quantitative IR-thermography. In this technique a hot spot is externally generated by a laser. The surface temperature measurements, from which the heat flux to the flow is derived, is measured externally by an IR-camera. The external heating and the extern al temperature measurement provides three main advantages: * the measurement is non-intrusive * the measurement point can easily be varied * th is technique can be applied in flight tests This measurements technique has been tested for a laminar flow along a flat plate in a wind-tunnel. The laser generates a hot spot on the plate until the steady state condition is reached. After turning off the laser the IR-camera monitors the temperature decay. From these data the heat flux to the flow and the wall-shear stress can be derived. The results show that it is indeed possible to apply quantitative IR-thermography to measure local wall-shear stresses. The obtained accuracy of the measurement technique is +/- 10% for free stream velocities larger than 10 m/s. However it has to be noted that this technique has some limitations due to the capabilities of the IR-camera, such as the spatial resolution and the signal to noise ratio. In the near future this measurement technique will be extended to flows with nonzero pressure gradients and with turbulence.","gas flow measurement; gas boundary-layer flow; aircraft dynamics; wind tunnels","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8666afa8-5868-4a1b-9f6c-497469c2db3a","http://resolver.tudelft.nl/uuid:8666afa8-5868-4a1b-9f6c-497469c2db3a","Vijftig jaar vliegtuigbouwkunde in Delft","","","1990","Dit Jubileumboek wordt uitgegeven ter gelegenheid van hel 50-jarig bestaan van de vliegtuigbouwkundige opleiding in Delft en hel negende lustrum van de Vliegtuigbouwkundige Studievereniging 'Leonardo da Vinci', Het boek heeft niet de pretentie een gedegen geschiedkundig overzicht Ie geven van de historie van de vliegtuigbouwkundige opleiding en van de studievereniging. In een 18-tal artikelen worden door medewerkers, oud-medewerkers en studenten uiteenlopende aspekten van het reilen en zeilen van de vliegtuigbouwkunde in Delft belicht. Het is een wat bonte verzameling geworden. waarvan wij niettemin verwachten dat het lezen ervan genoegen zal verschaffen aan hen, die he! hebben meegemaakt en dat het voor de jongeren interessant genoeg is om er kennis van te nemen. Hopelijk zal de inhoud ook voor komende generaties van waarde blijken te zijn.","","nl","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ad12ed62-1869-4daa-86b1-ea2785163a1d","http://resolver.tudelft.nl/uuid:ad12ed62-1869-4daa-86b1-ea2785163a1d","Base flow and exhaust plume interaction. Part 1: Experimental study","Schoones, M.M.J.; Bannink, W.J.","","1998","An experimental study of the flow field along an axi-symmetric body with a single operating exhaust nozzle has been performed in the scope of an investigation on base flow-jet plume interactions. The structure of under-expanded jets in a co-flowing supersonic free stream was described using analytical and physical models. Results of a single nozzle plume with a high supersonic exit Mach number of 4 exhausting in co-flowing supersonic free streams of Mach 1.96 and 2.98 are presented for a number of jet stagnation pressure to free stream static pressure ratios, ranging from Ptj/ Poo = 350 to no-jet flow at Mach 1.96 and from Ptj/ Poo = 600 to no-jet flow at Mach 2.98. The data consists of detailed five-hole probe Pitot pressure and flow direction surveys behind the model across the plume and of dynamic surface pressure measurements at the base of the model using three separate pressure taps. The five-hole probe Pitot pressure surveys clearly show the physical nature of the flow, e.g., the location of the various shock waves, expansion fans, and shear layers. The dynamic base pressure signals showed a resonance frequency of the pressure transducers. After filtering out the resonance frequency no distinct frequency was present in the dynamic base pressure signais. Apart from signal noise the base pressures showed a steady behaviour.","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:abeccae1-1c4d-4033-9aec-485797ca7819","http://resolver.tudelft.nl/uuid:abeccae1-1c4d-4033-9aec-485797ca7819","De zilveren en bronzen penningen van de Faculteit der Luchtvaart- en Ruimtevaarttechniek","Wittenberg, H.","","1999","","geschiedenis; luchtvaart","nl","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ec0d1dc2-7347-48a7-9264-d5004d0f5d30","http://resolver.tudelft.nl/uuid:ec0d1dc2-7347-48a7-9264-d5004d0f5d30","User's Manual for the Computer Program Cufus: Quick Design Procedure for a CUt-out in a FUSelage Version 1.0","Heerschap, M.E.","","1997","","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:25767235-c751-437e-8f57-0433be609cc1","http://resolver.tudelft.nl/uuid:25767235-c751-437e-8f57-0433be609cc1","DASMAT-Delft University Aircraft Simulation Model and Analysis Tool: A Matlab/Simulink Environment for Flight Dynamics and Control Analysis","Van der Linden, C.A.A.M.","","1998","Computer Assisted Design (CAD) environments have become important devices for the design and evaluation of flight control systems. For general use, different aircraft and operational conditions should be easily implemented in such a CAD environment and it should be equipped with a set of simulation and analysis tools. To extend its functionalities, it is best integrated in a highperformance computing environment with an extensive library of control design routines. This report documents the CAD environment DASMAT, which stands for Delft University Aircraft Simulation Model and Analysis Tool. It operates in the computing environment MATLAB/SIMULINK, having highperformance numeric s computation and visualization functionalities. The essential element in the DASMAT package is a generic nonlinear simulation model conceived with well-defined and generalized interfaces. For linear flight control design, the package contains special tools for trimming and linearizing the aircraft at user-defined operating points. A finished design may be evaluated by visualizing the time behaviour in nonlinear simulations. Both on-line and off-line analysis functions are available with the possibility of 3D flight-path and attitude visualization trough animation. For analyzing flight test data, the package also includes identification routines of which results are easily implemented in the simulation model. After a short introduction of DASMAT, this book focuses on the models, signals and variables present in the DASMAT package. The operational aspects for the simulation and analysis tools are discussed next, followed by the application of the DASMAT package for control design purposes. The appendices include a complete list of files of the DASMAT package, the complete lists of signal formats and all essential variables used in the generic models, and the lay-out plus equations of the SIMULINK models.","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:219f1427-16fd-436b-b1db-690084283d81","http://resolver.tudelft.nl/uuid:219f1427-16fd-436b-b1db-690084283d81","Residual thermal stresses around bonded fibre metal laminate repair patches on an aircraft fuselage","Vlot, A.; Soerjanto, T.; Yeril, I.; Schelling, J.A.","","1998","Residual stresses are present after elevated temperature cure of adhesively bonded patches to cracked aircraft structures. These residual stresses will affect the performance and the durability of the repair. Strain and temperature measurements were taken on a real aircraft fuselage section during and after repair at three locations. Thermal buckling of the skin was observed and therefore a precuring at a lower temperature was employed. Also at a lower temperature a significant outward bending of the skin was observed which influences the residual stresses. The measured temperature field corresponded weil with the theoretical model of Rose.","aircraft materials; aircraft structures","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:229f2817-9be9-49b6-959a-d653b5bac054","http://resolver.tudelft.nl/uuid:229f2817-9be9-49b6-959a-d653b5bac054","Synthesis of subsonic airplane design","Torenbeek, E.","","1982","","vliegtuigbouwkunde","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:96d1f1dd-df63-4175-a5c3-df32c16e7a32","http://resolver.tudelft.nl/uuid:96d1f1dd-df63-4175-a5c3-df32c16e7a32","A method for the determination of the effect of propeller slipstream on the static longitudinal stabiliy and control of multi-engined aircraft","Obert, E.","","1997","The method makes possible the determination of slipstream eftects on wing lift-off pitching moment and flow cond itions at the horizontal tail","","en","book","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4f43d498-065f-4f61-b074-9012c59dccc9","http://resolver.tudelft.nl/uuid:4f43d498-065f-4f61-b074-9012c59dccc9","Application of the virtual crack closure technique to calculate stress intensity factors for through cracks with an oblique elliptical crack front","Fawaz, S.","","1998","Fractographic observations on fatigue tested 2024 T3 clad aluminium riveted lap-splice joints indicate oblique fronts after the initial surface or corner crack at a rivet hole has penetrated through the sheet thichness. No stress intensity factor solutions are available for this geometry subjected to remote biaxial tension, remote bending, rivet loading, and rivet interference, which are typical for a pressurized fuselage of a transport aircraft. However, comparisons are made with solutions from the literature for remote tension and bending. To reduce model generation time for each crack geometry, one finite element mesh is used to generate a model for each crack geometry for which a stress intensity factor solution is desired. In using this procedure, the original orthogonal mesh, a mesh where all of the crack plane elements are orthogonal to one another, is modified to accommodate the new crack geometries; therefore, maintaining an orthogonal crack-front mesh is not possible. The validity of the three dimensional Virtual Crack Closure Technique, 30 VCCT, with non orthogonal finite element meshes for calculating mode I stress intensity factors is assessed. Comparisons are made to existing two and three dimensional stress intensity factor solutions obtained using conformal mapping, boundary collocation, and finite element analysis. Given a sufficiently fine mess, the 30 VCCT result is practically invariant to mesh pattern. Using the 30 VCCT with a non orthogonal mesh, a cursory sensitivity study is accomplished to asses the effect of the crack profile of a through crack on the stress intensity factor. If a through crack with an oblique elliptical shape is approximated as a straight crack, the stress intensity factors are nearly the same for remote tension but not for remote bending.","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3078d20c-2173-4c13-a4d7-106207c78577","http://resolver.tudelft.nl/uuid:3078d20c-2173-4c13-a4d7-106207c78577","ICSHM 2013: Proceedings of the 4th International Conference on Self-Healing Materials, Ghent, Belgium, 16-20 June 2013","De Belie, N.; Van der Zwaag, S.; Gruyaert, E.; Van Tittelboom, K.; Debbaut, B.","","2013","Symposium organised by Ghent University, Department of Structural Engineering and Delft University of Technology, Aerospace Structures & Materials. Materials play an extremely important role in our lives. These materials may be of a very different nature ranging from metals over concrete to polymers and composite materials. They all have in common to carry loads, to cope with forces and especially to be durable, because maintenance, repair or replacement may be difficult, costly or in some cases nearly impossible. With a continuous drive for better materials with lower weights that are costing less, materials may be positioned at the edge of their performance. On the contrary when safety and reliability are extremely important factors, materials usually are over-dimensioned for the added safety. All strategies developed over the past 20 centuries to improve the strength and reliability of materials, are ultimately based on the paradigm of “damage prevention”, i.e. the materials are designed in such a way that the damage as a function of load and/or time is postponed as much as possible. The level of damage will here never go down spontaneously. In recent years, however, it has been realized that an alternative strategy can be followed to make materials effectively stronger and more reliable, and that is by “damage management”, i.e. these materials have a built-in capacity to repair the damage incurred during use. When cracks form, the material itself is capable of “self-healing” the crack and restoring the functionality of the material. This approach, inspired by nature, captures the imagination of scientists and laymen alike. Biological systems such as bones, skin or plants have the capacity to detect damage very quickly and have moreover the unique feature to repair the damage efficiently. We would like to translate this concept to our engineering materials. With the series of International Conferences of Self-Healing Materials, we want to offer participants a full overview of the developments in this exciting and rapidly evolving field. The mission of ICSHM is to attract a diverse and multidisciplinary group of scientists and engineers coming from academia, industry and government agencies, managers, and policy makers, from all over the world.","self healing materials; self-healing cementitious materials; self-healing thermoplastic/thermoset polymeric materials; self-healing supramolecular polymers; self-healing fiber-reinforced composite materials; self-healing coatings and paints; self-healing metallic and ceramic materials; self-healing materials for functional applications; microvascular systems; bio-inspired materials; advanced characterisation methods for self-healing; modelling of self-healing and numerical analysis tools; societal impact of self-healing materials; bituminous materials","en","book","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:8b39c2d4-7bd7-4d83-b479-03ead1074ffb","http://resolver.tudelft.nl/uuid:8b39c2d4-7bd7-4d83-b479-03ead1074ffb","Spectral analysis of individual realization LDA data","Tummers, M.J.; Passchier, D.M.","","1998","The estimation of the autocorrelation function (act) or the spectral density function (sdt) from LDA data poses unique data-processing problems. The random sampling times in LDA preclude the use of the spectral methods for equi-spaced samples. As a consequence, special data-processing algorithms are used to process the LDA data. However, the random sampling causes an additional statistical variability of the spectral estimates that obscures the behaviour of the sdf in the high frequency range. The maximum frequency at which reliable estimates can be made is usually less than the mean data rate. For LDA measurements in gas flows the mean data rate is often small compared to the highest frequencies of the velocity fluctuations. As a consequence, the small scales of the turbulent fluctuations cannot be studied from the estimated sdf's with the presently available data-processing methods. It is the objective of the present study to modify an existing data-processing method such that information on the spectral density can be revealed at much higher frequencies. The modification consists of two elements. First, a locally sealed autocorrelation function is computed. This modification of the conventional slotting technique results in a much lower statistical variance at small lag times. Next, the locally scaled acf is cosine-transformed using a lag window whose width is varied with frequency. The modified estimator is applied to two types of stimulated data to illustrate its performance. It is shown that the modified slotting technique in conjunction with a variable window forms a powerful spectral estimator for low data density flows.","gas flow measurement","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d9507571-21c1-459c-a0fe-b2255824d1a4","http://resolver.tudelft.nl/uuid:d9507571-21c1-459c-a0fe-b2255824d1a4","Predictive control: A lecture course given in the Aerospace Engineering Faculty TU Delft","Maciejowski, J.M.","","1998","These notes were written for a course of 14 two-hour lectures on Model Predictive Control given to students at the Technical University of Delft in November and December 1997.","nonlinear control systems: theory","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:00bbcb0b-fe18-4adc-9a4c-2eda539a0c92","http://resolver.tudelft.nl/uuid:00bbcb0b-fe18-4adc-9a4c-2eda539a0c92","The Significance of Fractography for Investigations of Fatigue Crack Growth under Variable-Amplitude Loading","Schijve, J.","","1998","","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:148dc7b2-c589-469b-970f-ca13214af336","http://resolver.tudelft.nl/uuid:148dc7b2-c589-469b-970f-ca13214af336","A New Method of Impregnating PEl Sheets for the In-Situ Foaming of Sandwiches","Provo Kluit, P.W.C.","","1998","A new method is described to make foamable films for the production of in-situ foamed sandwiches. The method consists of placing a polymer film in a bath with a swelling agent and, when equilibrium swelling has been reached, placing the film in a bath with a second liquid. If the liquids are miscible the swelling agent in the film will be replaced by the second liquid. The polymer used for the research described in this report was polyetherimide and the swelling agent was acetone. Sandwiches were produced with the fomable films made in th is manner using ethanol, 1,1,1- trichloroethane and water as blowing agents. Some mechanical properties of these sandwiches were tested.","bewerking; plastic folie; sandwich panelen","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3fc91471-8e47-4215-af43-718740e6694e","http://resolver.tudelft.nl/uuid:3fc91471-8e47-4215-af43-718740e6694e","Fundamentals of astrodynamics","Wakker, K.F.","","2015","This book deals with the motion of the center of mass of a spacecraft; this discipline is generally called astrodynamics. The book focuses on an analytical treatment of the motion of spacecraft and provides insight into the fundamentals of spacecraft orbit dynamics. A large number of topics are treated in a uniform and consistent way. The text is intended for senior undergraduate or graduate engineering students, and is based on course notes that have been used in various versions since 1976 for courses given for M.Sc. students at the Faculty of Aerospace Engineering of Delft University of Technology. It is a typical student study book: the knowledge of mathematics and mechanics required from the reader corresponds to that of students having a B.Sc. degree, and full derivations of the formulas are given. However, the book is also useful for astrodynamicists and is a valuable resource for anyone interested in astrodynamics. The text starts with a treatment of the foundation of dynamics. It continues with the clas-sical topics of the many-body problem and the three-body problem, and modern applications of the three-body problem for spaceflight are presented. Then, it is proved that the motion of planets, satellites and interplanetary spacecraft can generally be approximated by a two-body problem. This problem is analyzed in full detail and many useful relations for circular, elliptical, parabolic and hyperbolic motion are derived. Next, the motion of a satellite relative to another satellite is discussed and analyzed, and the more modern topic of regularization is treated. Then, the basic astronomical concepts of reference frames, coordinate systems, orbital elements and time are presented, and various topics which are crucial in modern astrodynamics are addressed. Next, the application of rocket engines to change the orbit of a spacecraft is treated, both for coplanar and for three-dimensional maneuvers. Subsequently, the theory of phasing orbits is presented and various cases are analyzed. Next, rendez-vous flights between two satellites are analyzed. Then, the launching of satellites is discussed and analyzed, as well as the execution of lunar and interplanetary flights, and the flight of space-craft along low-thrust trajectories. The last four chapters deal with various aspects of orbit perturbations. The perturbing forces acting on a satellite are discussed and special and general perturbations methods are described. An elementary analysis of the character¬istic effects of the perturbing forces on a satellite orbit is given. The general method of variation of orbital elements is described in detail and an application to orbit maneuvers is presented. Finally, a detailed analysis of orbit perturbations due to the Earth=s gravity field is given. The book concludes with three appendices, containing additional information.","classical dynamics; astrodynamics; analytical methods; gravity field; rocket thrust; astro-nomical concepts; orbital elements; many-body problem; three-body problem; Keplerian orbits; regularization; transfer orbits; rendez-vous flights; launching of spacecraft; lunar flights; interplanetary flights; low-thrust trajectories; perturbing forces; orbit perturbations","en","book","TU Delft Library","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9ff3c7e0-e221-4d8f-bf9e-e144d3cacdc1","http://resolver.tudelft.nl/uuid:9ff3c7e0-e221-4d8f-bf9e-e144d3cacdc1","Elements of airplane performance (second edition)","Ruijgrok, Ger J.J.","","2009","","airplane performance","en","book","VSSD","978-90-6562-203-7","","","","","","","Aerospace Engineering","","","","",""
"uuid:48da3ba8-a55e-47ed-b7c0-d01c8f5bc8de","http://resolver.tudelft.nl/uuid:48da3ba8-a55e-47ed-b7c0-d01c8f5bc8de","The Two-Dimensional Soundfield of a Vortex Moving Around the Sharp Edge of a Half-Plane","Schouten, G.","","1998","","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e4604e1d-e874-4455-b0ac-72cadc5a45c1","http://resolver.tudelft.nl/uuid:e4604e1d-e874-4455-b0ac-72cadc5a45c1","Linear temporal stability analysis","Moeleker, P.J.J.","","1998","An infinite flat plate covered with a thin layer of a power-law fluid sheared by an air stream is considered. The equations and boundary conditions governing the temporal linear stability problem are derived assuming small disturbances superimposed on a steady primary flow. The latter consists of a Blasius boundary-layer flow for the air stream and an exact solution of the Navier-Stokes equations for the thin fluid layer. Sources of change in kinematic energy and enstrophy are identified. A spectral collocation method based on Chebyshev polynomials is implemented and the resulting algebraic problem is solved using a QZ-algorithm. An isolated Blasius boundary-layer flow showed instability above a critical Reynolds number (approx. 300) for a range of wave numbers (Blasius mode). The presence of a thin fluid layer introduced, next to the (hardly changed) Blasius mode, an additional unstable mode (interfacial mode) exhibiting smaller amplification rates and a larger range of instability. The Blasius mode instability is driven mainly by the Reynolds stress and the interfacial mode by the action of viscosity. This research has been carried out within the framework of predicting the dynamic behaviour of a thin layer of liquid (e.g. water or anti-icing fluid) sheared by an air flow.","multiphase flow; gas boundary-layer flow","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8b0fef4f-4255-4ed8-bc5f-fee657d90fc6","http://resolver.tudelft.nl/uuid:8b0fef4f-4255-4ed8-bc5f-fee657d90fc6","Contributions to the theory of aircraft structures: Presented to A. van der Neut by friends, colleagues and former students","","","1972","","aerodynamica; aircraft dynamics; wind tunnels","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:710605ee-ee17-49c8-9e8b-aaa44164af91","http://resolver.tudelft.nl/uuid:710605ee-ee17-49c8-9e8b-aaa44164af91","Bonded repairs for aircraft fuselages","Vlot, A.; Verhoeven, S.; Nijssen, P.J.M.","","1998","This report will give an overview of the bonded repair work that has been done over the last few years by the Faculty of Aerospace Engineering of Delft University of Technology, in cooperation with the Center for Aircraft Structural Life Extension at the United States Air Force Academy in Colorado Springs.","","en","book","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2d91e1e2-3dec-4371-b5ce-8205f9b752d8","http://resolver.tudelft.nl/uuid:2d91e1e2-3dec-4371-b5ce-8205f9b752d8","Complex-Systems Design Methodology for Systems-Engineering Collaborative Environment","Mooij, E.; Corpino, S.; Ridolfi, G.","","2012","OA-fund TU Delft","","en","book chapter","InTech","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f85862dc-2173-4e9f-8399-500caa248d02","http://resolver.tudelft.nl/uuid:f85862dc-2173-4e9f-8399-500caa248d02","Multi-Functional Guidance, Navigation and Control Simulation Environment-Rapid Prototyping of Space Simulations","Mooij, E.; Ellenbroek, M.","Hoque, M.E. (contributor)","2011","","OA-Fund TU Delft","en","book chapter","InTech","","","","","","","","Aerospace Engineering","","","","",""
"uuid:609698c6-a681-4284-84ae-42f6a282570e","http://resolver.tudelft.nl/uuid:609698c6-a681-4284-84ae-42f6a282570e","Development of an Aircraft Routing System for an Air Taxi Operator","Van der Zwan, F.M.; Wils, K.; Ghijs, S.S.A.","","2011","","","en","book chapter","InTech","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:1f47e072-ce98-4479-9176-bff9d1bbdfdb","http://resolver.tudelft.nl/uuid:1f47e072-ce98-4479-9176-bff9d1bbdfdb","Development of a Time-Space Diagram to Assist Air Traffic Controllers in Monitoring Continuous Descent Approaches","Mulder, M.; Van Paassen, M.M.; Tielrooij, M.; In 't Veld, A.C.","","2010","","OA-publication; Open Access Fonds","en","book chapter","SCIYO","","","","","","","","Aerospace Engineering","Control & Simulation Division","","","",""
"uuid:74ca4187-b72a-4080-9d24-3f58af6bfb72","http://resolver.tudelft.nl/uuid:74ca4187-b72a-4080-9d24-3f58af6bfb72","Effects of Automatic Flight Control System on Chinook Underslung Load Failures","Pavel, M.D.","","2012","","","en","book chapter","InTech","","","","","","","","Aerospace Engineering","Aerospace Structures & Design Methodology","","","",""
"uuid:0a91cf96-fe40-48e8-a4a6-71104dcf083f","http://resolver.tudelft.nl/uuid:0a91cf96-fe40-48e8-a4a6-71104dcf083f","Rotorcraft Design for Maximized Performance at Minimized Vibratory Loads","Pavel, M.D.","","2011","","","en","book chapter","InTech","","","","","","","","Aerospace Engineering","Aerospace Structures & Design Methodology","","","",""
"uuid:ea560062-5b59-4d25-a94b-5114e12cc6d1","http://resolver.tudelft.nl/uuid:ea560062-5b59-4d25-a94b-5114e12cc6d1","Automated 3D modeling of buildings in suburban areas based on integration of image and height data","Khoshelham, K.","","2006","","building extraction; automation; geometric modeling; LiDAR","en","book chapter","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:73f7f82f-a675-469a-8821-28f93ed5e321","http://resolver.tudelft.nl/uuid:73f7f82f-a675-469a-8821-28f93ed5e321","Measuring Sector Complexity: Solution Space-Based Method","Abdul Rahman, S.M.B.; Borst, C.; Mulder, M.; Van Paassen, M.M.","","2012","","","en","book chapter","InTech","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:559ea794-a57b-4506-a2c4-60dd92763ec3","http://resolver.tudelft.nl/uuid:559ea794-a57b-4506-a2c4-60dd92763ec3","GNSS Carrier Phase-Based Attitude Determination","Giorgi, G.; Teunissen, P.J.G.","","2012","","","en","book chapter","InTech","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:d336a49a-3754-4a6e-b7f4-7fd8c51d9002","http://resolver.tudelft.nl/uuid:d336a49a-3754-4a6e-b7f4-7fd8c51d9002","Overview of PIV in supersonic Flows","Scarano, F.","","2008","","","en","book chapter","Springer Berlin","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d9591f49-da1a-4b75-bc55-5cd92dbcf91d","http://resolver.tudelft.nl/uuid:d9591f49-da1a-4b75-bc55-5cd92dbcf91d","Aircraft bi-level life cycle cost estimation","Zhao, X.; Verhagen, W.J.C.; Curan, R.","","2015","n an integrated aircraft design and analysis practice, Life Cycle Cost (LCC) is essential for decision making. The LCC of an aircraft is ordinarily partially estimated by emphasizing a specific cost type. However, an overview of the LCC including design and development cost, production cost, operating cost and disposal cost is not provided. This may produce biased cost estimates. Moreover, aircraft LCC estimation is largely dependent on the availability of input parameters. It is often a problem for the analyst to supply a limited group of data into a detailed cost estimation process. Therefore, it is necessary to provide flexibility in conducting both high level and detail level LCC assessments based on the data accessibility. An input-dependent bi-level LCC estimation method is proposed. It illustrates the comprehensive estimation of the cost elements in the LCC with clearly defined high level and detail level analyses to form the final cost. Knowledge of the product and the life cycle process are structured based on a pre-defined meta model and logic rules. Cost is then evaluated by traversing the meta model linked with computing capabilities. This method is applied on a case study concerning A330-200 aircraft. With the support of weight estimation and bottom-up process-based parametric cost estimation methods, it builds up a practical costing approach in quantifying the influence of LCC to the product life cycle.","Life Cycle Cost; cost estimation; design for cost","en","book chapter","IOS Press","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:f3576a6e-e1d6-4e08-89f1-f8f72a7e7bcc","http://resolver.tudelft.nl/uuid:f3576a6e-e1d6-4e08-89f1-f8f72a7e7bcc","Thermal infrared observations of heterogeneous soil-vegetation systems","Jia, L.; Menenti, M.","","2010","","","en","book chapter","Research Signpost","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:33cebd11-ecb7-45d5-8989-fa9e1dfab341","http://resolver.tudelft.nl/uuid:33cebd11-ecb7-45d5-8989-fa9e1dfab341","Time-based Spaced Continuous Descent Approaches in Busy Terminal Manoeuvring Areas","Mulder, M.; Van Paassen, M.M.; De Gelder, N.; Meijer, L.K.","","2010","","Open Access Publication","en","book chapter","SCIYO","","","","","","","","Aerospace Engineering","Control & Simulation","","","",""
"uuid:1be7b34d-1b7d-46bc-bf20-ebb1888f2fb2","http://resolver.tudelft.nl/uuid:1be7b34d-1b7d-46bc-bf20-ebb1888f2fb2","PIV Investigation of Supersonic Base Flow: Plume Interaction","van Oudheusden, B.W.; Scarano, F.","","2008","","","en","book chapter","Springer Verlag","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3d4a29b7-83b1-4034-a460-45172d6f77a1","http://resolver.tudelft.nl/uuid:3d4a29b7-83b1-4034-a460-45172d6f77a1","Tomographic 3D-PIV and Applications","Elsinga, G.E.; Wieneke, B.; Scarano, F.; Schröder, A.","","2008","","","en","book chapter","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f3746c29-2e89-44b2-a715-45ad732501cd","http://resolver.tudelft.nl/uuid:f3746c29-2e89-44b2-a715-45ad732501cd","Stiffness-force feedback in UAV tele-operation","Lam, T.M.; Mulder, M.; Van Paassen, M.M.","Lam, T.M. (contributor)","2009","","","en","book chapter","In-Tech Education and Publishing","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:693d3060-9f3e-4ef3-a718-eb6e6b6e420d","http://resolver.tudelft.nl/uuid:693d3060-9f3e-4ef3-a718-eb6e6b6e420d","An Agile Cost Estimating Methodology for Aerospace Procurement Operations: Genetic Causal Cost CENTRE-ing","Curran, R.; Watson, P.; Cowan, S.","","2011","","","en","book chapter","InTech","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:9a118b0a-9273-4804-9db1-e38e7c67c8a2","http://resolver.tudelft.nl/uuid:9a118b0a-9273-4804-9db1-e38e7c67c8a2","Analysis of vegetation response to climate variability using extended time series of multispectral satellite images","Menenti, M.; Jia, L.; Azzali, S.; Roerink, G.; Gonzalez-Loyarte, M.; Leguizamon, S.","","2010","","","en","book chapter","Research Signpost","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:3b742af4-a95b-47cf-8d95-b25eb2b5aa42","http://resolver.tudelft.nl/uuid:3b742af4-a95b-47cf-8d95-b25eb2b5aa42","Advanced control techniques for post-buckled precompressed (PBP) flight control actuators","Groen, M.; Van Schravendijk, M.; Barrett, R.; Vos, R.","","2009","The dynamic response of a new class of flight control actuators that rely on post-buckled recompressed (PBP) piezoelectric elements is investigated. While past research has proven that PBP actuators are capable of generating deflections three times higher than conventional bimorph actuators, this paper quantifies the work output and power consumption under various axial loads, at various frequencies. An analytical model is presented that supports the experimental findings regarding the increasing work output and natural frequency shift under increasing axial loads. Furthermore, increasing axial loads shows an increase in open-loop piezoelectric hysteresis, resulting in an increasing phase lag in actuator response. Current measurements show an electromechanical coupling that leads to power peaks around the natural frequency. Increasing axial loads has no effect on the power consumption, while increasing the work output by a factor of three, which implies a significant increase in work density over the piezoelectric material itself.","post-buckled precompressed; PBP; actuator control; power consumption; peizoelectric","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5e669455-da2b-4cf4-8338-6b4643984b2a","http://resolver.tudelft.nl/uuid:5e669455-da2b-4cf4-8338-6b4643984b2a","Organization of an axisymmetric turbulent wake in presence of a central protrusion","Gentile, V.; Schrijer, F.F.J.; Van Oudheusden, B.W.; Scarano, F.","","2015","Stereoscopic Particle Image Velocimetry (PIV) was used to study the wake of an ogive-cylinder with after-body at a diameter-based Reynolds number ReD = 6.7 · 104. The vertical fluctuations reduced from a maximum of 0.18 U? in absence of rear-protrusion, up to 0.12 U? and 0.1 U? when the main-body to after- body diameter ratio d/D was increased to 0.2 and 0.4 respectively. For d/D = 0.2 the trace of the backflow centroid motion reflected the occurrence of a random motion where no pattern associated with a consistent precession of the reverse flow region can be identified, whereas a preferred azimuthal direction could be detected for d/D = 0.4. Proper Orthogonal Decomposition showed that modes k = 1, 2 contribute up to 20% and 11% of the turbulent kinetic energy, for d/D = 0.2 and d/D = 0.4 respectively. For d/D = 0.2 the two modes were found to be paired and to feature a dipole organization which is linked to a displacement of the wake in all azimuthal directions. For d/D = 0.4 only the first mode exhibited such an arrangement, thus reflecting wake displacement occurring along a preferred azimuthal direction.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:af7544a9-0e4d-41e3-8b14-e5474675863a","http://resolver.tudelft.nl/uuid:af7544a9-0e4d-41e3-8b14-e5474675863a","Aerodynamic Analysis of a Vertical Axis Wind Turbine in a Diffuser","Geurts, B.M.; Simao Ferreira, C.; Van Bussel, G.J.W.","","2010","Wind energy in the urban environment faces complex and often unfavorable wind conditions. High turbulence, lower average wind velocities and rapid changes in the wind direction are common phenomena in the complex built environments. A possible way to improve the cost-efficiency of urban wind turbines is the application of flowenhancing structures on or near the turbines. For horizontal axis wind turbines (HAWTs), applying a diffuser has shown to have a beneficial impact on the power production, but it is still under development. For a vertical axis wind turbine (VAWT) it is expected that flow augmentation will also strongly increase the performance of the turbine, but very little research has been done in this field. The purpose of this research is to investigate the effects of a diffuser on the airflow through a VAWT. In order to investigate these effects, the turbine (with and without diffuser) is simulated using a 2-D unsteady free-wake potential-flow panel model. The local flow field, local angles of attack, shed vorticity, the shape and strength of the wake, and the rotor torque are investigated for both the case with and without the diffuser. The diffuser used in this research consists of two mirrored airfoil cross-sections. The size of the duct-opening in which the turbine operates is varied. This work shows that unlike for a 1-D actuator disc analysis, the area ratio B of the diffuser exit with respect to the diffuser nozzle area is not the only driving factor in the augmentation of the rotor torque of the VAWT. More important are the effect of the directional change of the rotor inflow and the faster downstream transport of the shed vorticity.","","en","conference paper","European Wind Energy Association","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:d77c1eba-e97a-4d76-a4e0-d6aad5f0d6cb","http://resolver.tudelft.nl/uuid:d77c1eba-e97a-4d76-a4e0-d6aad5f0d6cb","Mimetic Least-Squares: A Least-Squares Formulation with Exact Conservation Properties","Bochev, P.; Gerritsma, M.I.","","2014","We present a spectral mimetic least-squares method which is fully conservative and decouples the primal and dual variables.","least-squares; mimetic methods; conservation; spectral methods","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:a9a1489c-8870-4336-8393-6a59ec4993d8","http://resolver.tudelft.nl/uuid:a9a1489c-8870-4336-8393-6a59ec4993d8","A methodological approach for the optimisation of the product development process by the application of design automation","Mulder, B.; La Rocca, G.; Schut, J.; Verhagen, W.J.C.","","2015","A short lead time of the Product Development Process (PDP) is an important competitive advantage for companies. Design automation solutions provide a means to reduce the lead time and improve quality, but their development requires some investment. Before a company can commit to the development of an automation initiative, it requires an estimation of the expected costs and benefits. The objective of this research is the development of a decision support system, based on multi objective optimization techniques and Discrete Event Simulation, to evaluate the effect of introducing automation solutions in a given PDP. The system is able to generate Pareto fronts showing optimum combinations of lead time reductions versus investment cost for automation. For each of the solutions on the Pareto front, the system provides the suggested list of PDP activities to be automated and their level of automation. The system functionality has been successfully demonstrated by means of a use case concerning the PDP of an aircraft component.","","en","conference paper","CEAS","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:a1fc6bdf-bb3a-4645-826d-37419ec47b81","http://resolver.tudelft.nl/uuid:a1fc6bdf-bb3a-4645-826d-37419ec47b81","Experiments on a hot plume base flow interaction at Mach 2","Blinde, P.L.; Schrijer, F.F.J.; Powell, S.J.; Werner, R.M.; Van Oudheusden, B.W.","","2015","A wind tunnel model containing a solid rocket motor was tested at Mach 2 to assess the feasibility of investigating the interaction between a hot plume and a high-speed outer stream. In addition to Schlieren visualisation, the feasibility of applying PIV was explored. Recorded particle images revealed that the hot plume scatters and reflects laser light, leading to a strong deterioration of the illumination conditions in regions within and near the plume. Suitable processing of the particle images could partly compensate for this and reliable velocity measurements could be obtained in directly illuminated regions. In regions near the base and below the plume, velocity measurements could still be obtained but were considered to be of lower quality. No reliable velocity measurements could be obtained within the plume itself.","","en","conference paper","ESA","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:1e04683e-9309-4f59-b451-4e33f95fe84b","http://resolver.tudelft.nl/uuid:1e04683e-9309-4f59-b451-4e33f95fe84b","Effect of Steering Limit Constraints on the Performance of Variable Stiffness Laminates","Peeters, D.M.J.; Abdalla, M.M.","","2015","A method to optimise the fibre angle distribution of variable stiffness laminates is proposed. The proposed method integrates a fibre angle retrieval step with a fibre angle optimisation procedure. A multi-level approximation approach is used in combination with the method of successive approximations. First, fibre angle retrieval is done by approximating the structural responses based on the optimal stiffness distribution found using lamination parameters. The full fibre angle optimisation is done by updating the approximations based on the current stacking sequence. It is shown for a bucking optimisation with a stiffness constraint that the number of finite element analyses reduces significantly by starting the optimisation from the optimal stiffness distribution rather than from a user-specified stacking sequence. Next, it is shown that updating the approximations also leads to considerable improvements over fibre angle retrieval. Similar promising results are obtained for a stress optimisation problem.","optimisation; variable stiffness; lamination parameters; manufacturability","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Computational Mechanics","","","",""
"uuid:0ec9edf7-5eac-4191-b63d-9a6c7e3619af","http://resolver.tudelft.nl/uuid:0ec9edf7-5eac-4191-b63d-9a6c7e3619af","Evolution of wind towards wind turbine","Giyanani, A.H.; Bierbooms, W.A.A.M.; Van Bussel, G.J.W.","","2015","Remote sensing of the atmospheric variables with the use of LiDAR is a relatively new technology field for wind resource assessment in wind energy. The validation of LiDAR measurements and comparisons is of high importance for further applications of the data.","wind evolution; remote sensing; lidar data; wind field modelling","en","conference paper","EAWE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:1c49bb87-0d52-4ba4-8100-921e0e9a7c1f","http://resolver.tudelft.nl/uuid:1c49bb87-0d52-4ba4-8100-921e0e9a7c1f","High-speed PIV analysis of trailing edge aeroacoustics","Pröbsting, S.; Serpieri, J.; Scarano, F.","","2013","Tonal noise generated by airfoils observed at low to moderate Reynolds numbers is related to laminar boundary layer instabilities, which has lead to the term laminar boundary layer instability noise. The particular features of the acoustic spectrum have been discussed and a number of theories have been proposed in literature over the past 50 years. Previous research suggests that the appearance of tonal noise is related to a feedback between the acoustic waves scattered at the trailing edge and the receptive part of the boundary layer [4]. Reported studies have been performed on the basis of hot-wire anemometry, laser doppler velocimetry, phase-locked PIV, acoustic measurements, numerical simulations or theoretical models. In recent years, PIV has become an alternative for the investigation of aeroacoustic sources. In particular the aeroacoustic sources for trailing edge noise have been investigated by Schröder et al. [10] using time-resolved PIV and Shannon and Morris [11] based on phase-locked PIV. Nakano et al. [8] focussed on the subject of laminar boundary layer instability noise on an airfoil and related their occurrence on the pressure side to noise emissions based on a correlation based technique. In the present study, planar high-speed PIV is performed simultaneously with acoustic far-field measurements. This combination allows to associate features of the acoustic emissions to events in the source field near the trailing edge for a better understanding of the tonal noise generation on an airfoil. In the past a wide range of Reynolds numbers has been investigated for different airfoil models, most notably the NACA0012 which is also selected for the present study. In particular, it is found that a periodic amplitude modulation of rapidly growing instabilities on the pressure side of the airfoil is responsible for the occurrence of multiple tones for the present configuration.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:3e47155c-7cde-4193-9607-dc161f46e248","http://resolver.tudelft.nl/uuid:3e47155c-7cde-4193-9607-dc161f46e248","APIAN-INF: A Low-Speed Aerodynamic and Aeroacoustic Investigation of Pylon – Pusher Propeller Interaction Effects","Sinnige, T.; Malgoezar, A.M.N.; Ragni, D.; Snellen, M.; Eitelberg, G.; Veldhuis, L.L.M.","","2015","An experimental investigation was performed at the Large Low-speed Facility of the German-Dutch wind tunnels (DNW-LLF) to study the pylon interactions associated with pusher propellers. The aerodynamic and aeroacoustic effects of pylon trailing edge blowing and swirl recovery vanes (SRVs) were evaluated. The pylon installation increased the summed tonal noise levels by up to 13 dB in unblown conditions, while the propulsive performance was affected in asymmetric inflow conditions only. At a sideslip angle of +6°, pre-swirl of the flow due to the pylon tip vortex led to a thrust increase of 10% at high thrust up to 45% at a low thrust setting. Stereoscopic PIV measurements showed the beneficial effect of pylon blowing in compensating the momentum deficit in the pylon wake. At the optimal blowing rate, a recovery effect of about 80% was obtained compared to the unblown case. Application of the blowing system eliminated the pylon installation penalty, recovering the noise levels to those measured for the isolated propeller. Installation of the SRVs downstream of the isolated propeller resulted in a swirl recovery of 50%, at the cost of a 2 dB tonal noise increase.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:b3422eaa-651a-4076-afbd-9607d22ad9ad","http://resolver.tudelft.nl/uuid:b3422eaa-651a-4076-afbd-9607d22ad9ad","Numerical Study on Control of Tollmien-Schlichting Waves Using Plasma Actuators","Kotsonis, M.; Giepman, R.; Veldhuis, L.L.M.","","2011","A numerical investigation on the use of plasma actuators for transition control is presented. The numerical framework involves the solution of the full unsteady 2D incompressible Navier Stokes equations using a finite volume formulation. The set of equations is formulated by solving for the perturbations in the flow while a mean laminar boundary layer flow is considered fixed and superimposed. The effect of the plasma actuator is represented as an imposed unsteady body force distribution derived from experimental measurements. Furthermore, an adaptive control system based on the filtered-x LMS algorithm is implemented directly into the flow solver. The control system uses pressure signals at the wall in order to compute the frequency, phase and amplitude of the plasma body force which minimizes the intensity of the propagating TS waves. Results show large reductions in wave amplitude for both single and multi frequency cases.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:0f6e7e3c-4a8c-46aa-9b22-b5206110d405","http://resolver.tudelft.nl/uuid:0f6e7e3c-4a8c-46aa-9b22-b5206110d405","Aeroelastic Modelling and Comparison of Advanced Active Flap Control Concepts for Load Reduction on the Upwind 5MW Wind Turbine","Barlas, A.; Van Kuik, G.A.M.","","2009","A newly developed comprehensive aeroelastic model is used to investigate active flap concepts on the Upwind 5MW reference wind turbine. The model is specially designed to facilitate distributed control concepts and advanced controller design. Different concepts of centralized and distributed control schemes based on choices of realistic measurement signals are compared. The sensitivity of important parameters to the load reduction capability is investigated and main differences between control approaches are analyzed. Conclusions are drawn regarding optimal integration of active flaps on wind turbines. Research work is performed at Delft University Wind Energy Research Institute (DUWIND), funded by EU’s FP6 project “UPWIND”.","","en","conference paper","European Wind Energy Association","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:3bc0cef7-fc5b-4670-b290-a69b3745a8cc","http://resolver.tudelft.nl/uuid:3bc0cef7-fc5b-4670-b290-a69b3745a8cc","Safe and swift performance, a conceptual assessment of a new river sea pusher system","Stoop, J.A.A.M.; Duinkerken, M.B.","","2008","","","en","conference paper","University of Strathclyde and Glasgow","","","","","","","","Aerospace Engineering","","","","",""
"uuid:be8bb0f3-75c9-4d2b-9696-e8275c62bacf","http://resolver.tudelft.nl/uuid:be8bb0f3-75c9-4d2b-9696-e8275c62bacf","Formation flying as an innovative air transportation system for long-haul commercial flight: A focus on operational feasibility and potential gain","Herinckx, L.E.; Gutleb, T.L.M.; Van Nunen, R.; Van Rompuy, E.; Bos, D.A.; Dijkers, H.P.A.; De Wit, J.; Radfar, H.; Sahin, S.E.; Beelarts van Blokland, W.W.A.","","2011","Formation flying is introduced as a new and innovative air transportation system for long-haul commercial flight. With this paper the operational feasibility of formation flying is addressed, both from a market demand and economic, as well as an air traffic control perspective. Preliminary results of a case study indicate that operating a newly designed aircraft that is optimized for formation flying could cut the fuel consumption over long-haul flights in half compared to current state-of-the-art aircraft. Therefore, this air transportation system proves to be a possible solution to the impending regulations and fines regarding the reduction of CO2 emissions in aviation.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8465ddea-79d5-49ce-98de-75acc61cf69c","http://resolver.tudelft.nl/uuid:8465ddea-79d5-49ce-98de-75acc61cf69c","Testing the untestable: Towards a pro-active safety assessment","Stoop, J.A.A.M.; Baggen, J.H.; Vleugel, J.M.","","2008","","proactive safety assessment; transportation","en","conference paper","IAPSAM","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8d6762a1-c041-40e7-b0e5-f6f541722c5e","http://resolver.tudelft.nl/uuid:8d6762a1-c041-40e7-b0e5-f6f541722c5e","A Modeling Framework for the Concurrent Design of Complex Space Systems","Ridolfi, G.; Mooij, E.; Chiesa, S.","","2010","The design of complex systems has become more and more articulated during the last decade, thus forcing radical modifications on the overall methodological approach. The authors developed a design methodology, which allows the user to design a particular category of complex systems usually called System-of-systems. This paper discusses the general framework to deal with the decomposition of a system-of-systems in its elements and sub-elements, to enable a faster and more effective solution of the problem, extending the applicability of the Concurrent Engineering paradigm to design phases that go beyond the preliminary/conceptual one. A hypothetical space exploration architecture, with a rover system, a lander system and an Earth-Moon transfer mission, have been implemented and discussed, linking the elements of this particular System-of-systems with a non-hierarchical decomposition approach and a multi-disciplinary feasible formulation.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:68108b2e-f488-4695-88ae-2d521c31d490","http://resolver.tudelft.nl/uuid:68108b2e-f488-4695-88ae-2d521c31d490","Evaluating GOCE data near a mid-ocean ridge and possible application to crustal structure in Scandinavia","Van der Wal, W.; Wang, L.; Visser, P.N.A.M.; Sneeuw, N.; Vermeersen, L.L.A.","","2011","GOCE gravity fields are assessed in an area around Reykjanes Ridge. Ship gravity measurements were found to be to inaccurate to determine possible improvement of GOCE gravity field models compared to the best available GRACE gravity field model. Differences between the GOCE gravity field models and EGM2008 does not appear to contain a component of the mid-ocean ridge signal. However the differences follow the Greenland coastline, which could indicate small errors in EGM 2008 there as a result of piecing together different gravity field observations. A Butterworth bandpass filter was applied to gradiometer observations at orbit height. After filtering, differences between repeat tracks with a magnitude of tens of mE are present, which can not be explained by position or attitude of the satellite. In order to reach the repeatability that can be expected from GOCE measurements, filtering methods need to improve. It was found that differences between global GRACE and GOCE gravity field models are small compared to uncertainty in crustal and upper mantle structure. Thus, geophysical inversion studies should focus on the gravity gradient observations in the instrument reference frame and at orbit height.","","en","conference paper","European Space Agency (ESA)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:9f6dc01d-9c5f-4fcb-8be6-9a9adb184ae3","http://resolver.tudelft.nl/uuid:9f6dc01d-9c5f-4fcb-8be6-9a9adb184ae3","Forensic engineering: Learning by accident. Teaching investigation skills to graduate students using real-life accident simulations","Saunders-Smits, G.N.; Schuurman, M.J.; Rans, C.D.","","2015","This paper relates the experiences of lecturers at Delft University of Technology in the designing and running of a Master course in Forensic Engineering. Rather than traditional face-to-face lectures, use of real-life evidence-based learning was made in the form of training for and execution of a mock aircraft accident investigation. The culmination of this learning experience for the students was the group exam, which took the form of the examination of a recreated accident scene. Students were required to organize their investigation groups, document the scene, and collect evidence while on scene. Subsequently, they were given time to analyze the results and prepare a standard accident investigation report. Evaluation results show satisfied students and good learning outcomes, making this a course worth repeating.","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:abc624e9-22f2-444c-aaf5-4c8d5de5e432","http://resolver.tudelft.nl/uuid:abc624e9-22f2-444c-aaf5-4c8d5de5e432","Stability of Optimal Solutions: Multi- and Single-Objective Approaches","Podgaets, A.R.; Ockels, W.J.","","2007","","Lyapunov methods,Pareto optimisation, optimal control, power generation, control robust control, stochastic systems, wind power","en","conference paper","IEEE","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ec50c811-b8b6-4a86-91f3-ec284e38d35c","http://resolver.tudelft.nl/uuid:ec50c811-b8b6-4a86-91f3-ec284e38d35c","Design and implementation of a new generation multi-agent task environment framework","Berends, J.P.T.J.; Van Tooren, M.J.L.; Schut, E.J.","","2008","","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5bf78a02-a4bf-4513-b1b8-4d9774993b3b","http://resolver.tudelft.nl/uuid:5bf78a02-a4bf-4513-b1b8-4d9774993b3b","A research proposal on behavioral interventions for intra-organizational adoption of e-procurement","Reunis, M.R.B.","","2005","","E-procurement adoption; technology adoption; behavioral intervention","en","conference paper","EIPM","","","","","","","","Aerospace Engineering","","","","",""
"uuid:03091774-0ba4-418a-bd12-9862dd7c4458","http://resolver.tudelft.nl/uuid:03091774-0ba4-418a-bd12-9862dd7c4458","Stabilisation Parameter Determination for the Stokes Equations","Chen, L.; Maher, G.D.; Hulshoff, S.J.","","2014","Parameters for SGS models within the variational multiscale method for the Stokes equations are determined using two different methods. Both linear and nonlinear models are considered. Firstly, optimal parameters are found using a goal-oriented model-constrained technique minimising L2 error. Secondly, parameters are obtained using the variational Germano identity. Using the goal-oriented results as reference values, it is shown that the performance of the Germano approach is sensitive to the form of the SGS model.","Variational Multiscale Method; stoke equations; stabilisation parameters; goal-oriented optimisation; Variational Germano Identity","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:08e0604e-0d0c-43db-8a57-354fecbf04d4","http://resolver.tudelft.nl/uuid:08e0604e-0d0c-43db-8a57-354fecbf04d4","Towards a miniaturized photon counting laser altimeter and stereoscopic camera instrument suite for microsatellites","Moon, S.G.; Hannemann, S.; Collon, M.; Wielinga, K.; Kroesbergen, E.; Harris, J.; Gill, E.K.A.; Maessen, D.C.","","2009","In the following we review the optimization for microsatellite deployment of a highly integrated payload suite comprising a high resolution camera, an additional camera for stereoscopic imaging, and a single photon counting laser altimeter. This payload suite, the `Stereo Imaging Laser Altimeter' SILAT has been designated for deployment aboard the FAST microsatellite formation mission for Earth observation. This instrument suite has been designed for a Jupiter mission, but has been redesigned and optimized for an Earth observation mission. This paper reviews the simulated Earth observation performance, the design modifications made for the mission and the optimization of the design for microsatellite use. Mass and power budgets are used to demonstrate the changes and the performance analysis is represented trough the simulation results. It is expected that the optimization will reduce the mass of the instrument by approximately 20\% without compromising the performance of the instrument. In addition, results from breadboarding experiments of individual instrument components will be presented to show the progress from design optimization towards the FAST flight model.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:107c7106-4fc7-4427-8d6d-7e56a9ec3d79","http://resolver.tudelft.nl/uuid:107c7106-4fc7-4427-8d6d-7e56a9ec3d79","Aerodynamic shape parameterisation and optimisation of novel configurations","Straathof, M.H.; Van Tooren, M.J.L.; Voskuijl, M.; Koren, B.","","2008","The Multi-Disciplinary Design Optimisation (MDO) process can be supported by partial automation of analysis and optimisation steps. Design and Engineering Engines (DEE) are useful concepts to structure this type of automation. Within the DEE, a product can be parameterically defined using Knowledge Based Engineering (KBE). This parameteric product model needs to be initiated before global multidisciplinary optimisation can be performed. This paper presents the first phase in the development of an aerodynamic initiator tool. This tool combines all aspects of the aerodynamic design process, thereby allowing the designer to efficiently determine a feasible aircraft shape that can be used as an initial state for the MDO. This research is performed as part of the CleanEra project at the Faculty of Aerospace Engineering at Delft University of Technology. The Class-Shape-Transformation (CST) method is used to create a parameteric description of a blended-wing-body (BWB) aircraft. The method is then expanded to allow for more local control of the aircraft shape. The mathematical description of the BWB is then translated to an input for the panel method program VSAERO, which outputs a number of relevant flow characteristics. These are then fed into an optimisation algorithm which generates a new aircraft shape and the process is repeated. The CST method has proven to be very useful as a parameterisation tool. VSAERO is considered sufficient for the flow analysis for now, but should later be replaced by a Euler or Navier-Stokes code. Work on the optimiser will start later this year.","","en","conference paper","Royal Aeronautical Society","","","","","","","","Aerospace Engineering","","","","",""
"uuid:bef3ae8a-5e63-44c7-b73c-bf46bf8b3052","http://resolver.tudelft.nl/uuid:bef3ae8a-5e63-44c7-b73c-bf46bf8b3052","SPEX: An in-orbit spectropolarimeter for planetary exploration","Snik, F.; Karalidi, T.; Keller, C.; Laan, E.; Ter Horst, R.; Navarro, R.; Stam, D.; Aas, C.; De Vries, J.","","2008","SPEX (Spectropolarimeter for Planetary EXploration) is an innovative, compact remote-sensing instrument for detecting and characterizing aerosols. With its 1-liter volume it is capable of full linear spectropolarimetry, without moving parts. High precision polarimetry is performed through encoding the degree and angle of linear polarization of the incoming light in a sinusoidal modulation of the intensity spectrum. This is achieved by using an achromatic quarter-wave retarder, an athermal multiple-order retarder and a polarizing beamsplitter behind each entrance pupil. Measuring a single intensity spectrum thus provides the spectral dependence of the degree and angle of linear polarization. Polarimetry has proven to be an excellent tool to study microphysical properties (size, shape, composition) of atmospheric particles. Such information is essential to better understand the weather and climate of a planet. Although SPEX can be used to study any planetary atmosphere, including the Earth’s, the current design of SPEX is tailored to study Martian dust and ice clouds from an orbiting platform: a compact module with 9 entrance pupils to simultaneously measure intensity spectra from 350 to 800 nm, in different directions along the flight direction (including two limb viewing directions). This way, both the intensity and polarization scattering phase functions of dust and cloud particles within a ground pixel are sampled while flying over it. In the absence of significant amounts of dust and clouds, the surface properties can be studied. SPEX provides synergy with instruments on rovers and landers, as it provides a global view of spatial and temporal variations of the planet.","aerosols; dust; Mars; spectropolarimetry","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","DEOS","","","",""
"uuid:b9ff9bdd-e021-4035-aa95-bd29ad424ab7","http://resolver.tudelft.nl/uuid:b9ff9bdd-e021-4035-aa95-bd29ad424ab7","Accuracy assessment of airborne laser scanning strips using planar features","Soudarissanane, S.S.; Van der Sande, C.J.; Khoshelham, K.","","2010","Airborne Laser Scanning (ALS) is widely used in many applications for its high measurement accuracy, fast acquisition capability, and large spatial coverage. Accuracy assessment of the ALS data usually relies on comparing corresponding tie elements, often points or lines, in the overlapping strips. This paper proposes a new approach to strip adjustment and quality assessment of ALS data by using planar features. In the proposed approach a transformation is estimated between two overlapping strips by minimizing the distance between points in one strip and their corresponding plane in the other. The planes and the corresponding points are extracted in a segmentation process. The point-to plane distances are used as observables in the estimation model, where the parameters of a transformation between two strips and their associated quality measures are estimated. We demonstrate the performance of the method on the AHN2 dataset over Zeeland province of The Netherlands. The dataset consists of 13 overlapping strips, from which a total of 522 gable roof and dike slope planes are extracted. The results show planimetric offsets between the strips that range from 3.13 cm to 55.32 cm. These offsets are in agreement with previously reported results using linear features. In addition, we estimated vertical offsets in the order of a few centimeters, which were not estimated in previous studies. The rotation parameters between the strips were also estimated; however, these did not show a significant difference in the orientation of the strips.","quality; strip adjustment; least-squares matching; planar features; error propagation","en","conference paper","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:bbd47c5d-468c-4d80-9733-adbb547ac41d","http://resolver.tudelft.nl/uuid:bbd47c5d-468c-4d80-9733-adbb547ac41d","Developing Operator Models for UAV Search Scheduling","Bertuccelli, L.F.; Beckers, N.W.M.; Cummings, M.L.","","2010","With the increased use of Unmanned Aerial Vehicles (UAVs), it is envisioned that UAV operators will become high level mission supervisors, responsible for information management and task planning. In the context of search missions, operators supervising a large number of UAVs can become overwhelmed with the sheer amount of information collected by the UAVs, making it difficult to optimize the information collection or direct their attention to the relevant data. Novel decisionsupport methods that account for realistic operator performance will therefore be required to aid the operators. This paper considers a decision support formulation for sequential search tasks, and discusses a non-preemptive scheduling formulation for a single operator performing a search mission in a time-constrained environment. The formulation is then generalized to include operator performance obtained from previous human-in-the-loop experiments, and presents one of the principal contributions of the paper. The sensitivity of the proposed model is analyzed in the presence of uncertainty to the operator model and search times, and a comparison is made between the expected performance difference between this scheduling system and a greedy scheduling strategy representative of operator planning. The paper concludes with the design of a human-in-the-loop experiment for a scheduling, replanning task for a simulated UAV mission.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1364e60c-0f1e-47b9-b7ca-2b7c476b7dfb","http://resolver.tudelft.nl/uuid:1364e60c-0f1e-47b9-b7ca-2b7c476b7dfb","An integral boundary layer method for modelling the effects of vortex generators","Baldacchino, D.; Ragni, D.; Simao Ferreira, C.J.; Van Bussel, G.J.W.","","2015","In this work, the measured modulated integral boundary layer (IBL) characteristics of low-profile vortex generators (VGs) are used to validate new developments in a viscousinviscid interaction code which is modified to incorporate the effect of the passive mixing devices. The motivations are laid out and sample validation data is presented within this abstract.","passive flow control; vortex generator; integral boundary layer; flat plate; RFOIL; PIV","en","conference paper","EAWE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:8ac637d4-a3b5-4237-b9e1-ff3fb1769a2d","http://resolver.tudelft.nl/uuid:8ac637d4-a3b5-4237-b9e1-ff3fb1769a2d","Solving the integral boundary layer equations with a discontinuous Galerkin method","Özdemir, H.; Van den Boogaard, E.F.","","2011","In this study the two-dimensional, unsteady integral boundary layer equations are solved numerically together with a closure set for laminar and turbulent flows. A high-order discontinuous Galerkin method is used for the spatial discretization and a multi-stage Runge-Kutta scheme is employed for the time integration. Numerical results show good agreement with the literature up to a separation point for steady problems.","integral boundary layer equations; closure models; discontinuous Galerkin method","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3690d3ce-6e4b-41ea-986c-9df109ced5c0","http://resolver.tudelft.nl/uuid:3690d3ce-6e4b-41ea-986c-9df109ced5c0","On the Estimation of Spanwise Pressure Coherence of a Turbulent Boundary Layer over a Flat Plate","Van der Velden, W.C.P.; Van Zuijlen, A.H.; De Jong, A.T.; Bijl, H.","","2014","A Large Eddy Simulation (LES) with four different closure models are analyzed in OpenFOAM, an open source Computional Fluid Dynamics (CFD) package and validated for the determination of the streamwise and spanwise coherence length of the pressure field below a turbulent boundary layer at low Reynolds numbers. Matching results are found for outer scaling mean and fluctuating velocity data as well as for the pressure spectrum data. The coherence function shows a similar decay with respect to various literature studies. An exponential fit is applied to determine the coherence length. Agreement within one displacement thickness error in streamwise and spanwise direction is found for the coherence length with semi-empirical data. The spanwise coherence length is considerably smaller than the streamwise coherence length, but indicates a clear peak in the low frequency regime originating from large coherent structures with relatively small amplitudes.","Computational Aero-Acoustics; Computational Fluid Dynamics; Large Eddy Simulation","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:2e0efe71-eda9-4088-9b37-2c7f06886a7f","http://resolver.tudelft.nl/uuid:2e0efe71-eda9-4088-9b37-2c7f06886a7f","Nonlinear Model-Based Fault Detection for a Hydraulic Actuator","Van Eykeren, L.; Chu, Q.P.","","2011","This paper presents a model-based fault detection algorithm for a specific fault scenario of the ADDSAFE project. The fault considered is the disconnection of a control surface from its hydraulic actuator. Detecting this type of fault as fast as possible helps to operate an aircraft more cost effective and can help to avoid an undetected increase in fuel consumption. The method proposed here uses an Adaptive Extended Kalman Filter (A-EKF) to detect the disconnection using only local measurements (control signal to the actuator and actuator rod position). For this purpose, an accurate physical model of the hydraulic actuator is needed and the fault is detected by parameter estimation. It is shown that the A-EKF performs better than the regular Extended Kalman Filter (EKF) for this application.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:260b4c88-98ce-4dc7-af11-9e4403cdd037","http://resolver.tudelft.nl/uuid:260b4c88-98ce-4dc7-af11-9e4403cdd037","Efficient nonlinear solver for unsteady CFD problems solved with higher order implicit time integration schemes","Lucas, P.; Bijl, H.","","2007","","","en","conference paper","Front Range Scientific Computations, Inc., Copper Mountain","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0f740082-b0b8-436c-8987-006402e2d646","http://resolver.tudelft.nl/uuid:0f740082-b0b8-436c-8987-006402e2d646","Development and Implementation of a Novel Parametrization Technique for Multidisciplinary Design Initialization","Straathof, M.H.; Van Tooren, M.J.L.; Voskuijl, M.; Vos, R.","","2010","A new parametrization method for aircraft shapes is presented to enhance shape optimization for aircraft design. This parametrization method was implemented in a tool that creates feasible initial solutions for multidisciplinary design optimization problems. The tool combines all aspects of the aerodynamic design process: parametrization, aero-dynamic analysis and optimization. The novel parametrization method presented in this paper makes use of the Class-Shape-Refinement-Transformation (CSRT) method. This method employs a combination of Bernstein polynomials and B-splines to allow for both global and local control of the shape. Additionally, the use of B-splines makes it possible to efficiently handle volume constraints, which are very common in aircraft design. The parametrization method was coupled to two different aerodynamic analysis tools. The commercial panel method code VSAERO was used for the low-speed regime and an in-house Euler code was used for transonic and supersonic flight conditions. Various different optimization schemes were investigated and compared. A number of test cases were performed. For the first set of test cases, a three-dimensional geometry was optimized for subsonic conditions, using VSAERO and various optimization algorithms. For the second set of test cases, an airfoil was optimized for transonic and supersonic conditions, using the in-house Euler solver and a gradient-based optimizer. From this work it can be concluded that a combination of stochastic and gradient-based optimization algorithms works best together with the CSRT method. Additionally, refining the shape using B-splines proved to be an efficient way of increasing the design freedom, while the design space remained smooth enough to employ gradient-based optimization.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:634f77cb-e99c-41e2-991a-fd8f542fa113","http://resolver.tudelft.nl/uuid:634f77cb-e99c-41e2-991a-fd8f542fa113","Individual tree detection based on densities of high points of high resolution airborne lidar","Abd Rahman, M.Z.; Gorte, B.G.H.","","2008","The retrieval of individual tree location from Airborne LiDAR has focused largely on utilizing canopy height. However, high resolution Airborne LiDAR offers another source of information for tree detection. This paper presents a new method for tree detection based on high points’ densities from a high resolution Airborne LiDAR. The advantage of this method is that individual trees are detected based on the densities of high points which distinctively separates crown centers from crown edges. Therefore, regardless of the crown shape, the center of a crown has a higher density than the edge of the crown. The densities of high points for each point in a dataset are calculated in a column with a specified window size. At the beginning, all points in the dataset are selected as candidate point for tree locations. The tree locations are further refined by using Inverse Watershed segmentation in which higher weights will have better chances to be selected as tree locations than points with lower weight. The method is tested on different tree species and tree conditions for a floodplain area in the Netherlands. The results of the tree detection are compared with the actual tree locations. It is found that this method can correctly predict more than 70 percent of trees under different tree conditions. This method is sensitive to the density of undergrowth vegetation, vegetation type, size of trees, and density of crown cover caused by overlapping tree crowns. Further work is required on using this information to optimize this method.","Airborne LiDAR; densities of high points; tree detection; Inverse Watershed segmentation; Canopy Height Model (CHM); Digital Terrain Model (DTM)","en","conference paper","University of Calgary, Canada","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:49cfb784-2ba0-4cf4-b4ee-f83a52db22ef","http://resolver.tudelft.nl/uuid:49cfb784-2ba0-4cf4-b4ee-f83a52db22ef","Unsteadiness Characterization in a Shock Wave Turbulent Boundary Layer Interaction through Dual-PIV","Souverein, L.J.; van Oudheusden, B.W.; Scarano, F.","","2008","","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3846d2ce-aecc-4c7d-b2fc-892177301c23","http://resolver.tudelft.nl/uuid:3846d2ce-aecc-4c7d-b2fc-892177301c23","Pseudo Control Hedging and its Application for Safe Flight Envelope Protection","Lombaerts, T.J.J.; Looye, G.H.N.; Chu, Q.P.; Mulder, J.A.","","2010","This paper describes how the previously developed concept of Pseudo Control Hedging (PCH) can be integrated in a Fault Tolerant Flight Controller (FTFC) as a safe flight envelope protection system of the first degree. This PCH algorithm adapts the reference model for the system output in case of unachievable commands due to control input saturation. As an example, this algorithm has been applied in the pitch rate and velocity control loops of a high fidelity Boeing 747 simulation model where its beneficial influence has been illustrated. The nonlinear adaptive control law used for this example is a triple layered nonlinear dynamic inversion algorithm, based upon the concept of time scale separation.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:38a8421c-0d0f-428e-9f8e-e4c32464fb60","http://resolver.tudelft.nl/uuid:38a8421c-0d0f-428e-9f8e-e4c32464fb60","Transonic airfoil aerodynamic characterization by means of PIV","Ashok, A.; Ragni, D.; Van Oudheusden, B.W.; Scarano, F.","","2008","","","en","conference paper","Calouste Gulbenkian Foundation","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f16ecd98-12d7-4c79-804d-7447e7c9df4c","http://resolver.tudelft.nl/uuid:f16ecd98-12d7-4c79-804d-7447e7c9df4c","Modeling and simulation of kite power systems","Schmehl, R.","","2011","","","en","conference paper","KU Leuven, OPTEC","","","","","","","","Aerospace Engineering","Aerodynamics and Windenergy","","","",""
"uuid:b1dff969-ec24-443a-b846-b989137a081e","http://resolver.tudelft.nl/uuid:b1dff969-ec24-443a-b846-b989137a081e","The future of single-frequency integer ambiguity resolution","Verhagen, S.; Teunissen, P.J.G.; Odijk, D.","","2009","The coming decade will bring a proliferation of Global Navigation Satellite Systems (GNSSs) that are likely to enable a much wider range of demanding applications compared to the current GPS-only situation. One such important area of application is single-frequency real-time kinematic (RTK) positioning. Presently, however, such systems lack real-time performance. In this contribution we analyze the ambiguity resolution performance of the single-frequency RTK model for different next generation GNSS configurations and positioning scenarios. For this purpose, a closed form expression of the single-frequency Ambiguity Dilution of Precision (ADOP) is derived. This form gives a clear insight into how and to what extent the various factors of the underlying model contribute to the overall performance. Analytical and simulation results will be presented for different measurement sce arios. The results indicate that low-cost, single-frequency GalileoCGPS RTK will become a serious competitor to its more expensive dual-frequency cousin.","ADOP; ambiguity resolution; single-frequency RTK","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:ce261122-e5e4-480d-b80c-b34cd60104b3","http://resolver.tudelft.nl/uuid:ce261122-e5e4-480d-b80c-b34cd60104b3","Probabilistic design with focus on blades","Veldkamp, H.F.","","2008","","","en","conference paper","Sandia National Laboratories","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e7fb0ed6-40b9-47b9-93e4-67d5561470ed","http://resolver.tudelft.nl/uuid:e7fb0ed6-40b9-47b9-93e4-67d5561470ed","Evaluation of Airport System of Systems from a Human Stakeholder Perspective using a Value Operations Methodology (VOM) Assessment Framework","Curran, R.; Smulders, F.; Van der Zwan, F.M.","","2011","This paper describes the development of the Airside Value Model. In the field of airport operations and airport performance measurement, there is much focus on ‘economical performance’. Additionally, Key Performance Indicators to assess airside operations are used, but these sets of KPIs are very diverse and the reasons for measuring them are not always clear. Moreover, these KPIs are not used to actually drive the operations at the airport’s airside. The Airside Value Model seeks to expand this limited domain by allowing airport managers to assess the Value created in their airside operations and use this information to optimize them. This Value measurement goes beyond just economical considerations, but also includes operational performance, environmental aspects et cetera. It has been shown that the Airside Value Model is able to measure these different aspects of Value and link them to operational processes. However, more work is required to enhance its effectiveness.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:a212a4af-fddd-4966-b03f-4a9cca4e85bb","http://resolver.tudelft.nl/uuid:a212a4af-fddd-4966-b03f-4a9cca4e85bb","Efficient uncertainty quantification in unsteady aeroelastic simulations","Witteveen, J.A.S.; Bijl, H.","","2009","An efficient uncertainty quantification method for unsteady problems is presented in order to achieve a constant accuracy in time for a constant number of samples. The approach is applied to the aeroelastic problems of a transonic airfoil flutter system and the AGARD 445.6 wing benchmark with uncertainties in the flow and the structure.","uncertainty quantification; stochastic collocation; unsteady; aeroelasticity","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:eab81e21-fe26-4726-981a-72f27635ef42","http://resolver.tudelft.nl/uuid:eab81e21-fe26-4726-981a-72f27635ef42","A study of process induced voids in resistance welding of thermoplastic composites","Shi, H.; Fernandez Villegas, I.; Bersee, H.E.N.","","2015","Void formation in resistance welding of woven fabric reinforced thermoplastic composites was investigated. Void contents were measured using optical microscopy and digital image process. Un-even void distributions were observed in the joints, and more voids were found in the middle of the joints than the edges. A higher welding pressure was shown to help reduce the void generation. The mechanisms of void formation, in particular fibre de-compaction induced voids and residual moisture induced voids, were analysed. The model estimations were correlated with the experimental results.","polymer-matrix composites; thermoplastic resin; joints/joining; voids","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:45f87ef5-f602-41c7-9cb2-3e05daed7a8e","http://resolver.tudelft.nl/uuid:45f87ef5-f602-41c7-9cb2-3e05daed7a8e","Design and testing of piezoelectric flight control actuators for hard-launch munitions","Barrett, R.; Lee, G.","","2004","A new technique is presented for designing actuators for guided hard-launch adaptive munitions by using actuator and substrate strain limits, static analysis methods and matching the local actuator strains along its length by varying the width. This Load-Matched design technique leads to an exponential area distribution as a function of length which is contrasted against the conventional rectangular actuator shapes that have been used in all adaptive hard-launch munitions up till now. To demonstrate the viability of this new Load-Matched actuator design, ten 600mg, 100mm long rectangular and ten identical mass and length, exponentially shaped, Load-Matched actuator specimens were designed and built to withstand the maximum possible accelerations. Predicted design static strain distributions are presented along with limits, showing that rectangular actuators exhibit a strong strain peak at the root while Load-Matched actuators have a much more even distribution and a gentle maximum near the middle. Shock table testing showed that the rectangular specimens were predicted to fail at 3,500g's, but survived acceleration levels 9.5 — 12% higher than expected (3,833 to 3,93 ig's). The exponentially shaped Load-Matched actuators proved that they could withstand shocks from 17 to 21% over the predicted failure acceleration level of 8,000g's (9,377 to 9,670g's).","piezoelectric; adaptive; munition; cannon shell; bullet; flight control","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","","","","",""
"uuid:36d9434e-1efa-4ad2-8990-78673b7794d3","http://resolver.tudelft.nl/uuid:36d9434e-1efa-4ad2-8990-78673b7794d3","Multiple healing in multi-functional polymer composites","Lafont, U.L.; Van Zeijl, H.; Van der Zwaag, S.","","2013","In this work, we investigate the formation of self-healing systems that are able to recover more than once more than one (mechanical or other physical) functionality. To this aim composites were created consisting of a polysulfide thermoset rubber matrix having intrinsic self-healing properties filled with thermally/electrically conductive particles. The cohesion, adhesion and thermal/electrical conduction recovery of these composites are investigated, monitored and quantified as function of the filler type and content. Moreover, the effects of healing temperature and the intrinsic polymer structure on the kinetics and degree of property recovery are explored.","composite; self-healing; dynamic bonding; adhesion; cohesion; thermal; conduction","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:ef0decdb-f710-4c89-8c32-a8e452926632","http://resolver.tudelft.nl/uuid:ef0decdb-f710-4c89-8c32-a8e452926632","A Case Study: Application of the Systems Engineering Modeling in the early phases of a Complex Space System Project","Bone, M.; Cloutier, R.L.; Gill, E.K.A.; Verma, D.","","2009","There is increased recognition of the role of systems engineering in reducing the risk (technical, cost, and schedule) on complex space systems development and integration projects. A number of international systems engineering standards have been published in the last five years (ISO 15288, IEEE 1220, and EIA 632). Closer to the space domain, NASA recently updated and finalized the NASA Systems Engineering Processes and Requirements guidelines (NPR 7123.1 and NPR 7120.5). Figure 1 represents an encapsulated perspective on the key systems engineering processes and their dependencies are articulated in the new NASA NPR 7123.1. The NASA acquisition framework (Figure 2) represents their recursive (across levels) and iterative (within a level) approach to the SE process, and includes milestones and reviews, as well as updates to those events. This paper will focus on the early phases of the systems engineering process. This represents the first two System Design Processes of Figure 1, and the Pre-Systems Acquisition Phase – the Pre-Phase A, Phase A and Phase B in Figure 2. The paper will walk through a case study of a space system from the initial problem statement to defining the architectural technical risk to the program. The case study will show how early system engineering tools such as User Scenarios, Quality Function Deployment, and selection matrixes can be used in the initial system decisions to satisfy the NPR process. Then Systems Engineering Modeling will be illustrated in the context of a space systems case study [2]. Unique concepts such as active and passive stakeholders, and stakeholder capabilities and characteristics will be articulated to reduce the risk of misalignment between stakeholder expectations and technical system requirements. A framework for articulating a defined space mission into a set of well expressed and aligned technical requirements will be presented that satisfies the NPR process.","System Engineering Process; milestone; modeling; Space System; NPR","en","conference paper","Research School of Systems Engineering, Loughborough University","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:e1ea5b9b-f85d-478f-81c7-82496a78b0cf","http://resolver.tudelft.nl/uuid:e1ea5b9b-f85d-478f-81c7-82496a78b0cf","A KBE Application for Automatic Aircraft Wire Harness Routing","Zhu, Z.; Van Tooren, M.J.L.; La Rocca, G.","","2012","Wire harness design is an increasingly complex task. Knowledge Based Engineering (KBE) and optimization techniques can be used to support designers in handling this complexity. The wire harness design process can be divided in three main parts, namely electrical design, configuration design and geometrical routing. This paper describes the latest progress in the development of a KBE application aiming at the automation of the routing phase. Discrete optimization techniques are used to design shortest path harnesses, while complying with different type of constraints. Some preliminary results have been presented in a previous paper, where only geometrical constraints were addressed. However, wire harness design is affected also by other types of rules and constraints, which need to be accounted to obtain more realistic design results from the optimization process. This paper describes some new developments in the routing application to account for the presence of critical zones inside the aircraft. As study case, the presence of heat sources inside the airframe is considered, which either force the harness to be routed elsewhere, or require the use of wire protections, with obvious consequences on weight and manufacturing. First, some mathematic transformation techniques are used to model the presence of heat sources inside the routing environment. Then the A* algorithm is used for compute the 3D routing, aiming at minimum wire harness weight. The main architecture of the routing application is presented and its functionality is demonstrated with samples of wire harness routing inside a wing. The results show that the proposed KBE application can automate the routing of wire harness while taking into account different rules and constraints. The modeling approach for a heat source can be generalized and extended to address other criticality such as abrasion, electromagnetic interference, corrosion, etc. The achieved level of automation relieves designers from the repetitive work associated with the frequent changes affecting the design environment.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:1a4de5c5-cef0-4396-819d-c4a76f50a180","http://resolver.tudelft.nl/uuid:1a4de5c5-cef0-4396-819d-c4a76f50a180","Dynamic communications for small satellites using disruption tolerant network concepts","Giuditta, N.; Gill, E.K.A.; Fernández, B.; Isaac, D.","","2009","New network technologies are providing interconnectivity in areas previously unheard of. One of these novel technologies, named Disruption Tolerant Networking (DTN), shows promise for the space industry. In order to study its suitability for University projects, a model of a University space mission has been created using network simulation software. This offers an insight into the characteristics, opportunities and challenges of this new technology. Disruption Tolerant Networking is a pioneering approach to network-based communications, seeking to resolve technical issues for nodes that lack continuous connectivity, which current Internet protocols cannot handle. The technology is currently being tested by several research bodies, and offers great potential for interoperability over heterogeneous networks. This paper focuses on the field of small satellites and the consequences of the future inception of DTN-based communications in upcoming space missions. Possible advantages include increased robustness to delays inherent to space communications as well as performance improvement, with little or no change to current communications infrastructure. To test this assertion, the FAST mission has been chosen as a case study. This mission is a collaboration between the TU Delft and Tsinghua University and it is composed of two small satellites tasked with performing an analysis of global aerosol data in the atmosphere. After using a simulated scenario, experimental results show the positive effect of the implementation of DTN protocols to perform payload data downlink in heavily disrupted communications environments, while pointing out areas where future work is needed to improve this investigation.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:0e75dbdf-81ae-4b92-bab7-b9d47bcff6b6","http://resolver.tudelft.nl/uuid:0e75dbdf-81ae-4b92-bab7-b9d47bcff6b6","Direct calculation of depth of correlation and weighting function in ?PIV from experimental particle images","Hein, M.; Wieneke, B.; Seemann, R.","","2013","Micro-PIV (?PIV) uses volume-illumination and imaging of fluorescent tracer particles through a single microscope objective. Displacement fields measured by image correlation depend on all imaged particles, including defocused particles. The measured in-plane displacement is a weighted average of the true displacement with a weighting function W(z), that depends on the optical system and gradients of the measured flow profile. The width of the weighting function W(z) is a measure for the distance to the focal plane up to which particles can influence the measured displacement (Depth of Correlation - DOC). We present two procedures to determine the DOC by comparing a measured displacement to a given displacement function and by directly measuring W(z) using PIV double-images generated from experimentally recorded particle-images. This allows to measure the DOC in dependence of out-of-plane gradients [4] and to include image preprocessing or different PIV-algorithms [5, 17]. Experimental results for different objectives and particle sizes are discussed, revealing deviations from theoretical predictions [1,2,3] for high NA air-objectives.","","en","conference paper","","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:b36b6759-38b2-43e0-ba4a-cb31a3b85827","http://resolver.tudelft.nl/uuid:b36b6759-38b2-43e0-ba4a-cb31a3b85827","Engine Management: A Decision Support Tool for Strategic Engine Maintenance Planning","Mayordomo, A.F.; Ghobbar, A.A.; Ghijs, S.S.A.; Cator, E.","","2010","This paper presents a model that helps engine management make cost saving decisions. The model is developed around airline-influenced factors that have an impact on engine Maintenance Repair & Overhaul (MRO): Operations, maintenance philosophy, contract type, and fleet age. Within the model a decision support tool is developed to analyze the impact of possible changes made to variables that influence engine MRO (engine thrust setting, shop visit schedule, and shop visit workscopes) on maintenance cost. The objective of the model is to support Engineering & Maintenance in defining a maintenance philosophy, which includes engine time on-wing and life limited parts management strategies. This maintenance philosophy will help with maintenance schedule optimization aiming at matching engine maintenance status to phase-out conditions at end of lease contracts, while at the same time reducing engine direct maintenance cost.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:c8905aa0-ba4b-45ca-bc07-7dc2a93fe3a9","http://resolver.tudelft.nl/uuid:c8905aa0-ba4b-45ca-bc07-7dc2a93fe3a9","Method to quantify the electrical efficiency of a ns-DBD plasma actuator","Avallone, F.; Correale, G.","","2015","An experimental investigation was conducted on the effective efficiency of a nanosecond Dielectric Barrier Discharge (ns-DBD) plasma actuator. Back-current shunt technique and infrared thermography measurements were carried out at the same time on an upside-down flat plate in a quiescent environment. The only investigated parameter was thickness of the dielectric barrier. Voltage amplitude and frequency of discharge were kept constant at maximum values allowable by the used power generator, i.e. 10k Volt and 10k Hz respectively. The selected material for the dielectric barrier was Makrolon(r) because of its well know thermal and dielectric propriety. Energy input was calculated as difference between the pulse voltage given and the one reflected back into the system via back current shunt technique. Ideal power flux obtained if all the input energy was converted to heat is then calculated. The actual power flux was obtained by solving an IHTP (Inverse Heat Transfer Problem) once the transient temperature distribution on the surface of the dielectric barrier was measured by means of IR thermography. The ratio between these two values represents a quantification of electrical efficiency of an ns-DBD plasma actuator. Results prove the high performances of ns-DBD plasma actuator in the respect of energy deposition and that the efficiency depends on the thickness of the barrier.","electrical efficiency; ns-DBD plasma actuator; IR thermography","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:cee6bccd-e21e-44b8-b8f9-d963a1813042","http://resolver.tudelft.nl/uuid:cee6bccd-e21e-44b8-b8f9-d963a1813042","Using the Mbes for classification of riverbed sediments","Amiri-Simkooei, A.; Snellen, M.; Simons, D.G.","","2008","","","en","conference paper","Société Française d'Acoustique","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:f65bdb74-b21d-490d-b715-fbfa6655b1d8","http://resolver.tudelft.nl/uuid:f65bdb74-b21d-490d-b715-fbfa6655b1d8","Application of a knowledge based design methodology to support fuselage panel design","van der Elst, S.W.G.; van Tooren, M.J.L.; Vermeulen, B.","","2008","","","en","conference paper","Royal Aeronautical Society","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8beb86d6-40a7-4c03-bc18-8512bb5bb548","http://resolver.tudelft.nl/uuid:8beb86d6-40a7-4c03-bc18-8512bb5bb548","A multidisciplinary design optimization advisory system for aircraft design","Hoogreef, M.F.M.; D'Ippolito, R.; Augustinus, R.; La Rocca, G.","","2015","This paper presents the status of development of an MDO advisory system, coupled to an optimization configurator for a process integration and design optimization (PIDO) system. This advisory system can support non-experts in the application of MDO by giving advice on the type of MDO architecture to use and assist in the implementation of the actual problem inside a PIDO system. Both the advisory system and optimization configurator are implemented by means of knowledge based technologies that allow for the inclusion of semantics to data and allow for semantic reasoning. An overview of the functionalities of the system and the background technology that is involved is presented in this paper. A use case is presented to illustrate part of the capabilities. This use case focuses on the (re)generation of (partial) MDO workflows. It is demonstrated that based on, user-specified, desired outputs only that part of a workflow that is relevant to these outputs can be automatically generated inside the PIDO system and executed.","","en","conference paper","CEAS","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:f7bfc22b-98ef-4086-a5c0-0b5972d56e65","http://resolver.tudelft.nl/uuid:f7bfc22b-98ef-4086-a5c0-0b5972d56e65","Vortex Formation and Force Generation Mechanisms of the DelFly II in Hovering Flight","Tenaglia, A.; Persin, M.; Van Oudheusden, B.W.; Deng, S.; Remes, B.","","2014","This paper addresses the unsteady aerodynamic mechanisms in the hovering flight of the DelFly II flapping-wing Micro Aerial Vehicle (MAV). Stereoscopic Particle Image Velocimetry (Stereo-PIV) were carried out around the wings at a high framing rate. Thrust-force was measured to investigate the relation between the vortex dynamics and the aerodynamic force generation. The results reveal that the Leading-Edge-Vortex (LEV), as well as the high flexibility of the wings, have a major effect on thrust generation. Comparison of three wing pairs with different aspect ratio (AR) is also reported, yielding significant differences in both vortical structures and thrust generation.","IMAV2014; MAV; Micro Air Vehicle; vortex formation; force generation mechanism; DelFly II; hovering flight","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:8a8d0058-2eed-44a9-9331-9962105e9c56","http://resolver.tudelft.nl/uuid:8a8d0058-2eed-44a9-9331-9962105e9c56","Higher dimensional numerical simulations of precipitate dissolution in multi-component aluminium alloys","Javierre, E.; Vuik, C.; Vermolen, F.J.; Segal, A.; Van der Zwaag, S.","","2006","In thermal processing of alloys, homogenization of the as-cast microstructure by annealing at such a high temperature that unwanted precipitates are fully dissolved, is required to obtain a microstructure suited to undergo heavy plastic deformation. This process is governed by Fickian diffusion and can be modelled as a Stefan problem. In binary alloys [1], the interface concentration is the solid solubility predicted from thermodynamics. However, addition of secondary alloying elements can influence the dissolution kinetics strongly [2]. In multicomponent alloys, the interface concentrations should satisfy a hyperbolic equation obtained from the Gibbs free energy of the stoichiometric alloy [3] and, therefore, have to be found as part of the solution. A wide range of numerical methods have been developed in the past to solve higher dimensional scalar Stefan problems. Of those, front capturing methods have shown to be the most adequate, especially when topological changes occur. Geometrical reductions are normally taken in the numerical solution of vector-valued Stefan problems. The aim of this work is to extend a numerical approach [1] implemented for scalar Stefan problems, which is based on the level set method [4], to higher dimensional vector-valued Stefan problems. This extension is obtained by adding a nonlinear coupling of the interface concentrations into the level set formulation. Computational simulations will be presented for one-, two- and three-dimensional problems, both for binary and multicomponent alloys. The numerical results will be compared with self similarity solutions for unbounded domains.","particle dissolution; vector-valued Stefan; level set method","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5fa66fdb-acbd-4a43-96bf-9729e1a0b2d8","http://resolver.tudelft.nl/uuid:5fa66fdb-acbd-4a43-96bf-9729e1a0b2d8","Low-fidelity 2D isogeometric aeroelastic optimization with application to a morphing airfoil","Gillebaart, E.; De Breuker, R.","","2015","Low-fidelity isogeometric aeroelastic analysis has not received much attention since the introduction of the isogeometric analysis (IGA) concept, while the combination of IGA and the boundary element method in the form of the potential flow theory shows great potential. This paper presents a two-dimensional low-fidelity aeroelastic optimization framework consisting of a loosely coupled isogeometric potential flow model and isogeometric curved Timoshenko beam model. Application of the framework to the optimization of the landing performance for an active morphing airfoil shows its potential, although the absence of viscosity in the aerodynamic model has a detrimental effect.","Low-fidelity aeroelasticity; isogeometric analysis; morphing airfoil; potential flow; curved Timoshenko beams","en","conference paper","Central Aerohydrodynamic Institute (TsAGI)","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:34bac75c-966b-4147-9433-f4a177c06f83","http://resolver.tudelft.nl/uuid:34bac75c-966b-4147-9433-f4a177c06f83","A robust and efficient uncertainty quantification method for coupled fluid-structure interaction problems","Witteveen, J.A.S.; Bijl, H.","","2009","A robust and efficient uncertainty quantification method is presented for resolving the effect of uncertainty on the behavior of multi-physics systems. The extrema diminishing method in probability space maintains a bounded error due to the interpolation of deterministic samples at constant phase in a transonic airfoil flutter problem.","uncertainty quantification; fluid-structure interaction; polynomial chaos; extrema diminishing; error bounds","en","conference paper","International Center for Numerical Methods in Engineering (CIMNE)","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:c60c9158-3a23-4381-aa6d-ecb04c8d071d","http://resolver.tudelft.nl/uuid:c60c9158-3a23-4381-aa6d-ecb04c8d071d","Trajectory Optimization Based on Interval Analysis","De Weerdt, E.; Van Kampen, E.; Chu, Q.P.; Mulder, J.A.","","2011","Trajectory optimization has been a large field of research for many years. The drawback is that for non-convex, constrained problems practically all available solvers cannot guarantee that the globally optimal trajectory is found. Interval analysis based solvers however can provide this guarantee. Interval analysis has been applied to trajectory optimization before, but the previously presented methods suffered from major drawbacks which limited their application to small scale problems. In this paper a new interval based method is introduced which incorporates state parameterization to prevent explicit integration. The performance of the proposed method is demonstrated by applying it to a spacecraft formation flying optimization problem. The results are compared with a gradient based solver and it is shown that the interval method is guaranteed to find the global optimal solution. Finally the first steps for another new trajectory optimization method based on interval analysis and direct collocation are presented.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:a52acbf0-dfa5-4aeb-9def-d72116cc0e12","http://resolver.tudelft.nl/uuid:a52acbf0-dfa5-4aeb-9def-d72116cc0e12","Tuning Models of Pilot Tracking Behavior for a Specific Simulator Motion Cueing Setting","Pool, D.M.; Damveld, H.J.; Van Paassen, M.M.; Mulder, M.","","2011","This paper describes the preliminary results of an effort to compile data from a large number of studies that investigated the effects of variations in motion filter settings on pilot behavior. The main objective of this study is to formulate a set of mathematical rules that will allow for the tuning of behavioral pilot models to a certain motion cueing setting. To achieve this, data for different dependent measures such as tracking performance, pilot-vehicle system crossover frequencies, and pilot model parameters, taken from ten different experiments that considered pilot tracking behavior under varying rotational or translational motion cueing settings, has been combined. By checking the correlation of the variation in any of these dependent measures and parameters that quantify the applied variation in motion cueing, a number of consistent relations has been identified. The most consistent and clear effects that are found from this analysis are variations in some important dependent measures with the motion filter gain at 1 rad/s. Over the full range of motion filter gains at 1 rad/s from 0 to 1, a reduction in pilot visual gain of around 20% is observed with reducing motion filter gain, in combination with a 30% increase in the amount of visual lead equalization adopted by pilots.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:946aab04-85e4-4d30-9e51-0c72034fff78","http://resolver.tudelft.nl/uuid:946aab04-85e4-4d30-9e51-0c72034fff78","Rotational Augmentation Disparities in the MEXICO and UAE Phase VI Experiments","Schreck, S.; Sant, T.; Micallef, D.","","2010","Wind turbine structures and components suffer excessive loads and premature failures when key aerodynamic phenomena are not well characterized, fail to be understood, or are inaccurately predicted. Turbine blade rotational augmentation remains incompletely characterized and understood, thus limiting robust prediction for design. Pertinent rotational augmentation research including experimental, theoretical, and computational work has been pursued for some time, but large scale wind tunnel testing is a relatively recent development for investigating wind turbine blade aerodynamics. Because of their large scale and complementary nature, the MEXICO and UAE Phase VI wind tunnel experiments offer unprecedented synergies to better characterize and understand rotational augmentation of blade aerodynamics. Cn means, Cn standard deviations, two-dimensional cp distributions, and three-dimensional planform surface pressure topologies from these two experiments were analyzed and compared. Rotating blade data were evaluated against analogous stationary blade data. Rotational augmentation effects were found to be pervasive and were present over the blade radius and throughout blade operating envelopes at all radial locations investigated. Rotational effects manifested themselves in both mean and time varying statistics, in both two-dimensional sectional data as well as three-dimensional planform data. Comparative analyses of MEXICO and UAE data validated and generalized current knowledge regarding rotationally augmented blade flow fields. In addition to confirming prior research, results also provided new insights not attainable by considering either data set in isolation of the other.","force amplification; rotational augmentation; wind tunnel; wind turbine; unsteady loading","en","conference paper","European Wind Energy Association","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:36b81e27-ac4f-43a1-8d9d-ec7dba730b63","http://resolver.tudelft.nl/uuid:36b81e27-ac4f-43a1-8d9d-ec7dba730b63","Real Time Adaptive Feedforward Guidance for Entry Vehicles","Sagliano, M.; Oehlschlagel, T.; Theil, S.; Mooij, E.","","2015","One of the most powerful analysis tools to deal with entry guidance problems is the possibility to formulate them as optimal control problems (OCPs). Environmental constraints, actuator limits, and strict requirements on the final conditions can be efficiently transcribed, resulting in a discrete, finite-dimension nonlinear programmming (NLP) problem. However, NLP problems require a computational power, which often exceeds the vehicle’s onboard capabilities. Moreover, it is important to ensure that the nominal optimal solution can be adapted to the actual flight conditions, which can significantly differ from the nominal scenario. This paper proposes an approach based on multivariate interpolation to generate entry guidance solutions. The real-time capability is ensured in virtue of the lower CPU efforts required to execute the interpolation operation. The approach is here proposed for initial-conditions variations, but can in principle be applied to every mission parameter, which allows to find a corresponding optimal solution. Results have been generated for SHEFEX-3, an entry demonstrator vehicle scheduled to be launched in 2016.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:36c700b2-9815-475b-a4bc-4b41549c3291","http://resolver.tudelft.nl/uuid:36c700b2-9815-475b-a4bc-4b41549c3291","A statistical model of the motion of pastels under vibration (Poster)","Sauvage, L.L.F.; Sangari, A.; Sethares, W.; Martinez, M.J.; Wei, W.","","2015","","","en","conference paper","TU Delft / Rijksmuseum","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:9a4658cf-bfc5-466c-9d3b-c6803eb9c843","http://resolver.tudelft.nl/uuid:9a4658cf-bfc5-466c-9d3b-c6803eb9c843","PIV-based surface pressure and aerodynamic loads determination on a transonic airfoil","Ashok, A.; Ragni, D.; Van Oudheusden, B.W.; Scarano, F.","","2008","","","en","conference paper","Delft University of Technology/EWA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:bdda4381-e237-42a7-aa94-f15baa17d1e5","http://resolver.tudelft.nl/uuid:bdda4381-e237-42a7-aa94-f15baa17d1e5","Functions of space and travellers","Van Passen, M.R.","","1999","","functional modelling; (air-)space use","en","conference paper","Group D Publications Ltd","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f25d2c00-294d-4f18-9f99-827f3cffb09b","http://resolver.tudelft.nl/uuid:f25d2c00-294d-4f18-9f99-827f3cffb09b","Aerodynamic Shape Optimization by means of Sequential Linear Programming Techniques","Carpentieri, G.; Van Tooren, M.J.L.; Koren, B.","","2006","An optimization framework for aerodynamic design on unstructured meshes has been implemented. It includes a finite volume solver based upon a median-dual discretization, its discrete adjoint, and shape parameterization and mesh moving/deforming algorithms. The framework elements are coupled and linked to a Sequential Quadratic Programming (SQP) optimization algorithm, taken from a library. The framework has been tested and found effective in the design of shock-free airfoils at transonic flow conditions. However, in general, shape optimization is not a rigorous process and many issues (e.g design variable bounds or constraints specifications) require user interaction in order to avoid unfeasible designs. Therefore, especially in the context of expensive aerospace applications, it is desirable to have an optimization procedure capable of achieving near optimal design and allowing the user to interact with the framework in order to gain more insight into the design space. The SQP algorithm, in spite of its effectiveness, limits the designer in using his engineering knowledge to steer the optimization process. A Sequential Linear Programming technique has been investigated as an algorithm more tailored to shape optimization problems in the preliminary design phase. The idea behind this algorithm is very simple: given a non-linear optimization problem (i) perform a linearization around the design point, (ii) solve the linearized problem using a Linear Programming algorithm to obtain a new design point, (iii) linearize around the new design point and solve again the Linear Programming problem until the minimum of the non-linear problem is found. A drawback of the algorithm is that for under-constrained design cases the linearized problem can be unbounded. To overcome this problem the domain resulting from the linearization must be reduced. The definition of the reducing factor is a crucial part in the algorithm and can affect the effectiveness and the efficiency of the optimization. The paper includes a brief introduction to the framework in which the discrete adjoint is addressed in terms of implementation and solution issues. After the introduction, the Sequential Linear Programming algorithm is discussed more in detail and demonstrated on different test cases.","Aerodynamic Shape Optimization; Sequential Linear Programming; unstructured meshes; adjoint equations","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:882bbb7e-ee6a-4764-abae-0c211a21ccfa","http://resolver.tudelft.nl/uuid:882bbb7e-ee6a-4764-abae-0c211a21ccfa","Investigation of the flow in a circular cavity using stereo and tomographic PIV","Haigermoser, C.A.H.K.; Scarano, F.; Onorato, M.","","2008","","","en","conference paper","ISFV","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7e2919b7-f164-40ca-a9a2-fd1e7b6d869f","http://resolver.tudelft.nl/uuid:7e2919b7-f164-40ca-a9a2-fd1e7b6d869f","Monitoring the restoration of interfacial contact for self healing thermal interface materials for LED and microelectronic applications","Lafont, U.L.; Van Zeijl, H.W.; Van der Zwaag, S.","","2013","While conventional self healing materials focus on the restoration of mechanical properties, newer generations of self healing materials focus on the restoration of other functional (i.e. non-mechanical) properties. Thermal conductivity is an example of an important functional property of a Thermal Interface Material (TIM) for LED’s and microelectronics devices. Current TIMs are optimized to provide thermal conductivity for as long a time as possible, yet these materials have no self healin potential and any crack formed will only lead to a decreased or lack of thermal conductivity and will dramatically reduce life time of the component. In order to get a better insight on how, as function of time, self-healing TIM systems are able to recover structural (cracks) and interfacial (delamination, adhesion) damages, we have developed a new specific technique to monitor local heat conduction. This technique probes very locally the heat transfer through the material to monitor changes related to heat conduction. If the material is damaged (cracked), the cracking or delamination will result in a thermal impedance restricting the thermal transfer. If the material is self healing, the local thermal conduction paths will be restored in time. In order to probe the thermal transfer for conventional and our new self healing TIM materials, a dedicated silicon chip containing an array of 49 diodes spaced uniformly over a 1 cm2 area has been fabricated. Using this device, it is possible to map with high spatial resolution the efficiency of the local thermal transfer and to relate it to the recovery of pre-imposed damage. Such experiments will yield unique local and temporal insight into cohesion and adhesion recovery of our self-healing polymeric systems.","self-healing; in-situ characterization; thermal conduction; interfacial damage recovery","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:a2fe6b0c-f471-42c4-8fa4-ffabf8b446db","http://resolver.tudelft.nl/uuid:a2fe6b0c-f471-42c4-8fa4-ffabf8b446db","Atmospheric stability and wind profile climatology over the North Sea: Case study at Egmond aan Zee","Sathe, A.R.","","2010","The statistics of atmospheric stability and non-dimensional wind profiles are studied using the standard surface-layer theory at Egmond aan Zee in the North Sea. Measurements at 21, 70 and 116 m are used to validate the theoretical profiles. Charnock’s relation is used to estimate the sea surface roughness. Bulk Richardson number is used to estimate the Obukhov length. The measured sea water temperature has a positive bias of 0.82?C resulting in the dominance of unstable conditions and a poor agreement of the theoretical wind profiles with the measurements. The conditions at Egmond aan Zee are dominated by unstable and neutral stabilities. The theoretical wind profiles agree very well with the measurements in the unstable and neutral conditions. In stable conditions, the wind profiles are over-predicted significantly as the height increases. The scaling of the wind profile with respect to the boundary layer height is necessary under stable conditions and the addition of another length scale parameter is preferred.","atmospheric stability; Obukhov length; wind profiles; boundary layer height; sea surface temperature","en","conference paper","European Wind Energy Association","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:9ae90164-ac0b-45fb-a477-631f57ed052e","http://resolver.tudelft.nl/uuid:9ae90164-ac0b-45fb-a477-631f57ed052e","Towards the next generation of nanosatellite communication systems","De Milliano, M.J.; Verhoeven, C.J.M.","","2008","The communication systems currently used on nanosatellites are usually well-proven commercial-off-the-shelf units with data rates up to 9.6 kbps. A careful analysis shows that by using advancements in microelectronics, a higher communication performance can be achieved, even within the power and mass limitations of a nanosatellite. This paper presents a new approach to maximize the performance of nanosatellite communication systems by taking a systems engineer’s perspective and by regarding the entire satellite instead of the communication system only. It is found that efficiency can be gained by also including the electrical power system in the design. The parameters that influence the performance of the communication system are identified. It is shown how these parameters can be tuned such that the limited resources on a nanosatellite are used most effectively. The results are used in designing the communication system of Delfi-n3Xt, the next nanosatellite mission of Delft University of Technology. The results presented in the paper can be used as a guideline to designing a nanosatellite of the next generation.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:a5b8033b-f4e1-4100-9e6a-ec9ff697019c","http://resolver.tudelft.nl/uuid:a5b8033b-f4e1-4100-9e6a-ec9ff697019c","Application of Least-Squares Spectral Element Methods to Polynomial Chaos","Vos, P.E.J.; Gerritsma, M.I.","","2006","This papers describes the use of the Least-Squares Spectral Element Method to polynomial Chaos to solve stochastic partial differential equations. The method will be described in detail and a comparison will be presented between the least-squares projection and the conventional Galerkin projection.","least squares; spectral elements; polynomial chaos; stochastic differential equations","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b92f2beb-5dac-47c8-84ab-f5e681c8081c","http://resolver.tudelft.nl/uuid:b92f2beb-5dac-47c8-84ab-f5e681c8081c","Improving 2D change detection by using available 3D data","Van der Sande, C.J.; Zanoni, M.; Gorte, B.G.H.","","2008","Change detection with very high resolution imagery is difficult, because 3D objects as buildings appear differently in 2D imagery due to varying viewing angles and sun positions. This research proposes a method to improve change detection by using simple 3D models of buildings. Buildings have been modelled as flat roof or gable roof buildings. By knowing the position of the sun, the location of the shadow of a building is calculated. The location of the relief displacements is calculated using information on the position of the sensor. By introducing the projected shadow, relief displacement and roof in the automatic change detection process more reliable change signals are produced. An object-oriented approach for change detection is developed using segmentation techniques to create homogeneous segments from pixels. The method compares the object map t0 with the image t1. Information is gathered on how each object represents in the image t1 and at t0, by using the information of the image t0. In the case of shadow parts histogram stretched imagery are used. For the change detection on the roof, the roof segments are reprojected on top of each other to compare them. This method resulted in more reliable change detection results and increased the detection rate to 72% for changes to buildings.","remote sensing; change detection; updating; segmentation; 3D; object oriented","en","conference paper","International Society for Photogrammetry and Remote Sensing","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:de72e000-1c1e-4dbe-83ec-a1aef880d60e","http://resolver.tudelft.nl/uuid:de72e000-1c1e-4dbe-83ec-a1aef880d60e","A knowledge based engineering approach to support automatic design of wind turbine blades","Chiciudean, T.G.; La Rocca, G.; van Tooren, M.J.L.","","2008","","multidisciplinary; design; integration; knowledge Based Engineering","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c3254303-43b7-4063-bffc-6ea149019d75","http://resolver.tudelft.nl/uuid:c3254303-43b7-4063-bffc-6ea149019d75","The role of clusters on the healing efficiency of a modified Zn based ionomer","Vega Vega, J.M.; Van der Zwaag, S.; Garcia Espallargas, S.J.","","2013","Poly(ethylene-co-methacrylic acid) (EMAA) ionomers have shown healing capabilities in both ballistic and static tests. In previous studies it was shown that the degree of crosslinking (clusters) affects (positively or negatively) the healing under impact tests. Moreover, it has also been reported that the modification of the ionomers by additives leads to different healing behaviours under static puncture tests. Despite the preliminary tests the effect of the additives on the ionomers was not clarified. In this work we use scratch healing and WAXS to gain a major understanding of the effect of additives in ionomers. Several blends of a semi-crystalline ionomer partially neutralized with zinc (EMAA-Zn) with adipic acid were prepared. Temperature assisted healing (well below the melting temperature) of artificial scratches in the surface of modified and unmodified EMAA-Zn ionomers was performed. A confocal microscope was employed for the healing quantification and measurements of Young modulus. Wide Angle X Ray diffraction (WAXS) was employed to track the effect of the additive in the polymer structure. The results show a strong influence of the additive on the clusters leading to a clear increase of the healing efficiency when clusters disappear.","EMAA; ionomer; WAXS; scratch healing","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:37a38ce1-8d62-4ce0-af1c-a57506b2ed80","http://resolver.tudelft.nl/uuid:37a38ce1-8d62-4ce0-af1c-a57506b2ed80","Effects of Heave Washout Filtering on Motion Fidelity and Pilot Control Behavior for a Large Commercial Airliner","Van Wieringen, A.T.; Pool, D.M.; Van Paassen, M.M.; Mulder, M.","","2011","Due to the significant translational heave motion at the pilot station associated with changes in aircraft pitch attitude, themotion cueing for aircraft pitchmaneuvering typically requires significant heave washout filtering. Previous studies that attempted to motivate choices in the motion cueing strategy for pitch maneuvering based on measurements of pilot behavior. For the small conventional aircraft considered in these studies, the results indicated that, despite the fact that pilots were found to adapt their control strategy to changes in heave cueing, the pitch rotation had a dominant influence on pilot behavior during pitch tracking. For large commercial airliners, a relevant application of this research as a lot of commercial pilot training occurs on moving-base simulators, the location of the pilot station is significantly further from the center of aircraft pitch rotation, yielding more pronounced heave motion cues during changes in pitch attitude. This difference, in addition to typically slower pitch dynamics that require more lead equalization, implies the best choice in motion cueing for large aircraft may be significantly different from what would be optimal for smaller aircraft. In this paper, an experiment is described in which pilot behavior is measured in a pitch attitude disturbance-rejection task with a controlled element and motion cueing conditions that are representative for a Boeing 747 aircraft. Different third-order heave washout filter settings were considered, in addition to a variation in the presence of 1-to-1 rotational pitch motion. Significant effects of the applied variation in pitch and heave motion cueing are observed, even though the effect of heave motion feedback is indeed found to be comparatively more important for larger aircraft. Furthermore, a heave motion filter that combined a low gain with low filter phase distortion was found to yield the least effect on pilot behavior, while for heave motion filters with a relatively high gain and high break frequency significantly larger contributions of motion feedback to pilot behavior were observed.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:4ea9be00-97d3-425c-9050-cb1ea17b6ff7","http://resolver.tudelft.nl/uuid:4ea9be00-97d3-425c-9050-cb1ea17b6ff7","TIGER capacity building facility: Growing from projects to professional community","Vekerdy, Z.; Su, B.; Menenti, M.; Swinnen, E.; Painho, M.; Fernandez, D.","","2010","Water security has become one of the most important challenges in the sustainable development of Africa, but only limited reliable information is available on the use and availability of water to support adequate planning and management of water resources. Data acquired from space can contribute to meet the urgent information need. But to satisfy the demand, a good synchronization based on a shared knowledge is required between water managers, who can indicate their specific information needs; developers of the satellite-based data, who can indicate what information can be provided; and the knowledge institutes, which transfer their knowledge on collection and dissemination of the information to users. In other words, a continent-wide capacity is needed to utilize Earth Observation (EO) technology. In the context of the Committee of Earth Observation Satellites (CEOS), ESA launched the TIGER Initiative in 2002 as a concrete action to match the resolutions of the World Summit on Sustainable Development held in Johannesburg. The initiative aims at assisting African countries to overcome problems faced in the collection, analysis and dissemination of water related geoinformation by exploiting the advantages of EO technology. The first phase was completed in 2008, which contained a capacity building facility (TCBF) that supported about 100 individuals from more than 20 institutions all around the continent with training at various levels and methods: 1. Basic education, provided via distance learning. 2. Tailored short courses, selected according to the research interest and technical background of the participants. 3. Research topic oriented supervision, provided by specialists of the research fields of the participants. 4. Advanced short courses focusing on selected earth observation techniques. ITC implemented the TCBF. Today we are in the second phase of the TIGER Initiative (TIGER II), which aims to build upon the success of the first one. TCBF II is implemented now by a consortium of four partners (ITC, TU Delft, VITO and ISEGI-UNL), with the aim of supporting 20 research projects and establishing 3 Regional Offices in the time span of 2009-2012. They support African efforts to develop sustainable observation systems by using EO technology to learn more about the water cycle and to improve water-monitoring resources that will help to establish sound scientific bases for developing effective adaptation or mitigation measures against the impacts of climate change. The TCBF focuses on the research component of TIGER II that supports African scientists furthering their scientific skills and the technical capacity to address the issue of the water resources in Africa. The second phase is more complex than its forerunner, although the applied capacity building tools are similar to the first phase. For example, the first training course on earth observation basics was held in Cairo in April 2010. Twenty three participants were supported by the TIGER programme, and another eleven joined using their own resources. There is a larger variety of participating institutions, from universities to regional water authorities. It is a very important aspect that several projects address trans-boundary issues with multinational staff. The participating institutions and regional offices get free access to ESA satellite data. A large number of training activities are being implemented with the aim of broadening the EO literacy among the information users, i.e. the water practitioners, and providing higher academic qualifications to the key players in EO research and education, to enable them to teach new generations of EO specialists and users in Africa. Besides capacity building, these activities contribute to building a community that unites the users of earth observation technology for water applications around the continent.","TIGER capacity building facility; water resources management; earth observation","en","conference paper","International Society of Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:4b61aabc-d8ef-4f6b-8442-d5a54dde8efc","http://resolver.tudelft.nl/uuid:4b61aabc-d8ef-4f6b-8442-d5a54dde8efc","Multidisciplinary Design of Flexible Aircraft","Baluch, A.; van Tooren, M.J.L.","","2008","","MDO; design framework; flexible aircrafts; fuselage structure; dynamic loads; minimum weight; stability constraints","en","conference paper","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c2b296ad-4da5-4ed4-b728-1a900372bad6","http://resolver.tudelft.nl/uuid:c2b296ad-4da5-4ed4-b728-1a900372bad6","Experimental Investigation of the Supersonic Wake of a Reentry Capsule","Schrijer, F.F.J.; Walpot, L.M.G.F.M.","","2010","The wake behind an Apollo shaped capsule is investigated in the framework of the ’afterbody heating’ topic in the RTO WG043 working group. Measurements are performed by means of schlieren, shadowgraphy and stereo particle image velocimetry (SPIV) and are used for CFD validation purposes. The model geometry is a scaled version of the AS-202. It was found from the shadowgraph results that the angle of attack where separation occurs decreases with increasing Mach number and is not influenced by the Reynolds number. Furthermore, it was possible to correlate the shear layer transition location using Re2,xt , which is the Reynolds number based on post normal shock conditions where the length scale is the flow path from stagnation point to transition point. SPIV measurements were obtained at Mach 2 and 0º and 25º angle of attack. For the 0º model, the wake was completely separated while for the 25º model the wake was partially separated and reattaches half way the model. Overall the PIV data return a quantitative three dimensional description of the velocity field around the capsule.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:d564cbc7-7cc8-40a8-a6b1-a567772e116d","http://resolver.tudelft.nl/uuid:d564cbc7-7cc8-40a8-a6b1-a567772e116d","Design, development and test of a compact lightweight capsule recovery system","Hausmann, G.; De Pascale, F.; Kruijff, M.; Mironov, M.","","2008","This paper reports about the development and test of a recovery system for small capsules, originally developed for the YES2 satellite launched in 2007, that included a miniature re-entry capsule, Fotino. The system includes a beacon and parachute, an activation system, and a compact spring-based parachute ejection system, initiated by a pyrotechnic device. Design challenges were low mass (few hundred grams), low volume (the ejection system is the size of a shoe-polish box) and (de)installation possible with minimal access. High ejection energy was required (about 15 J) to eject the parachute even reliably from a spinning fast-dropping capsule. The system can be used for recovery of lightweight capsules and probes released from orbit, sounding rockets or high altitude balloons. The overall design approach has been hands-on, goal-oriented and pragmatic, due to time and budget constraints. Pros and cons of this approach are highlighted. The paper reports on design, trade-offs and the successful qualification of the various systems involved and the mechanism in particular. Unfortunately the capsule has not been recovered yet, but analysis of its whereabouts and possible reasons of lack of beacon signal will be discussed. Nevertheless, a reflight is foreseen, as the successful qualification and overall mass and dimensional properties make the recovery system an attractive option for future small capsules and probes.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:cdd395af-55b5-42e1-8f93-10b51c1dfbb1","http://resolver.tudelft.nl/uuid:cdd395af-55b5-42e1-8f93-10b51c1dfbb1","Implementation and validation of a model of the MPI Stewart platform","Nieuwenhuizen, F.M.; Van Paasen, M.M.; Mulder, M.; Bülthoff, H.H.","","2010","A simulated model of the MPI Stewart platform can be used to identify the influence of motion system characteristics on human control behaviour in active closed-loop control experiments on the SIMONA Research Simulator. In this paper, a previously identified model of the MPI Stewart platform was analysed with describing function measurements, and it was found that a reduced form of the model was sufficient to capture the relevant dynamics. The reduced model was simulated on the SIMONA Research Simulator and describing function measurements were performed with two IMUs. Both IMUs revealed a resonance peak in measurements of response magnitude at the highest frequencies. A reduced time delay was found with the newer IMU. With the describing function measurements, the implementation of the MPI Stewart platform model was validated in terms of the frequency response and the time delay.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:76a97302-a307-493a-86d1-e5fec3d6b497","http://resolver.tudelft.nl/uuid:76a97302-a307-493a-86d1-e5fec3d6b497","Experimental Investigation of the Flapping Performance on 'Delfly Micro'","Deng, S.; Van Oudheusden, B.W.; Remes, B.D.W.; Persin, M.; Bijl, H.; Ruijsink, H.M.","","2013","","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:eb93ab51-6d35-41ca-a3db-f714775521cd","http://resolver.tudelft.nl/uuid:eb93ab51-6d35-41ca-a3db-f714775521cd","Impact of fuel composition on emissions and performance of GTL kerosene blends in a Cessna Citation II","Snijders, T.A.; Melkert, J.A.; Bogers, P.F.; Bauldreay, J.; Wahl, C.R.M.; Kapernaum, M.G.","","2011","International jet fuel specifications permit up to 50% volume Fischer-Tropsch synthetic paraffinic kerosines (FT-SPKs), such as Gas-to-Liquids (GTL) Kerosine, in Jet A-1. Higher SPK-content fuels could, however, produce desirable fuels: lower density, higher SPK-content fuels may have benefits for Payload range (P/R) performance and their chemistry should improve many engine emissions. Two sets of GTL-containing Jet A-1s, with 0-50% GTL, have been tested both in the laboratory and in a Cessna Citation II, with Pratt & Whitney Canada JT15D-4 turbofan engines. Smoke Point and lower heating values (LHVs) confirm previous work that showed GTL improving performances to above and/or beyond typical Jet A-1 levels. Smoke points are sensitive to the type of aromatics in the fuel while LHVs are more affected by the total aromatics levels. Ground tests (with performance, post test inspections and emissions measurements) have been run. Specifically, one engine has been run according to ICAO power settings with the addition of cruise settings, and probes behind the engine have captured gaseous and particulate emissions. Under all conditions, fuel flow rates are lower than expected; under cruise conditions there is about a 5% reduction for 50% blends. Filters that remove particulates in gaseous emissions lines clearly indicate a progressive improvement with increasing GTL/decreasing total aromatics content. At all engine settings, the particle diameter, emission index in terms of particle number and emission index in terms of particle mass all decrease significantly with GTL content. For gaseous emissions, emissions indices for SO2, NO, NO2, NOx (NO+NO2) and CO have been tracked for each engine setting. SO2 reductions are seen clearly for the higher sulphur base fuel blends, consistent with the reduction in fuel sulphur content. There is a very small reduction of NOx at higher power settings and a 5-10% reduction on CO emissions for 50% GTL at most engine conditions.","","en","conference paper","International Association for Stability, Handling (IASH)","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:3f9e87cc-1b90-431f-bcc1-8a79324471d8","http://resolver.tudelft.nl/uuid:3f9e87cc-1b90-431f-bcc1-8a79324471d8","Emissions testing on gas-to-liquid kerosene blends","Snijders, T.A.; Melkert, J.A.","","2011","The search for alternative fuels has lead to a number of possibilities. The most promising alternative fuels for the short term are drop-in fuels such as synthetic fuel and hydrotreated renewable jet. These fuels are similar to Jet A-1 but some differences are present. Synthetic fuels are produced using a process that results in a fuel without trace elements and almost no aromatics. Furthermore, synthetic fuels have a higher energetic content and lower gravimetric density than Jet A-1. These differences cause several effects when considering the use of synthetic fuel in aircraft. A performance model is used to show that the payload-range performance is changed and that an efficiency gain is achieved on the fuel consumption for a regular flight. Measurement of the soot emissions for several blends of synthetic fuel with Jet A-1 show that increasing the amount of synthetic fuel leads to significant reductions in soot emissions. Reductions of 50 to 70% in particle mass emitted can be reached by using 50% synthetic fuel. This might reduce the amount of contrails and aircraft induced cirrus clouds and seriously increase local air quality around airports.","","en","conference paper","TU Delft","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:c3f08ede-af06-4673-ae76-1565fbec680a","http://resolver.tudelft.nl/uuid:c3f08ede-af06-4673-ae76-1565fbec680a","Influence of atmospheric conditions on the range distance and number of returned points in Leica Scanstation 2 point clouds","Hejbudzka, K.; Lindenbergh, R.C.; Soudarissanane, S.S.; Humme, A.","","2010","The aim of this research is to analyze experimentally the influence of atmospheric conditions on a series of measurements obtained by a terrestrial laser scanner. The scan series represents a dike covered by containers. These containers are gradually filled with water during the experiment to simulate a controlled dike collapse. From the morning of 25.09.2008 till the afternoon of 27.09.2008 two kinds of measurements were made. The first one assessed the atmospheric condition by measuring variations in radiation, temperature and humidity, which were taken as weather attributes for future analysis. The second measurements were made by the terrestrial laser scanner ScanStation 2 from Leica. During the experiment a total of 159 scans with a resolution of 5 cm on 50 m distance of the dike were made. On the scanned region twelve stable virtual targets were selected based on intensity and range. Three scan attributes were determined for each target at each of the 159 epochs: number of observed points, mean distance between scanner and target, and also standard deviation of these distances. The resulting scan attributes are compared to the 3 atmospheric attributes described above. The results indicate that scans affected by fog can be detected automatically by analyzing independent meteorological data. A weak linear relation of about 2 mm range increment per degree temperature increment at 70 m distance should be further investigated.","terrestrial laser scanner; atmospheric condition; point density; range accuracy","en","conference paper","International Society of Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:fcf4d3b2-9f3c-4fd1-8ec7-1c44d90a33e2","http://resolver.tudelft.nl/uuid:fcf4d3b2-9f3c-4fd1-8ec7-1c44d90a33e2","Optimization of Spacecraft Rendezvous and Docking using Interval Analysis","Van Kampen, E.; Chu, Q.P.; Mulder, J.A.","","2010","This paper applies interval optimization to the fixed-time multiple impulse rendezvous and docking problem. Current methods for solving this type of optimization problem include for example genetic algorithms and gradient based optimization. Unlike these methods, interval methods can guarantee that the globally best solution is found for a given parameterization of the input. The state transition matrix approach for the linearized CW-equations is used to avoid interval integration. Thruster pulse amplitudes are optimized by an interval branch and bound algorithm, which systematically eliminates parts of the control input space that do not satisfy the final time state constraints. Interval analysis is shown to be a useful tool in both sensitivity analysis and nonlinear optimization of the rendezvous and docking problem.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:0303cd2e-8d69-4ee6-96bd-dce806a8b688","http://resolver.tudelft.nl/uuid:0303cd2e-8d69-4ee6-96bd-dce806a8b688","An MDO advisory system supported by knowledge-based technologies","Hoogreef, M.F.M.; La Rocca, G.","","2015","Multidisciplinary Design Optimization (MDO) can aid designers to improve already mature design solutions, as well as to explore innovative, complex engineering products. It is a methodology, complete with mathematical formulations, that assists in the optimization of a complex product, whilst considering and exploiting discipline interactions. Although the first MDO applications have been developed decades ago, this discipline is not yet fully exploited within industry. One of the main reasons is the lack of understanding due to the inherent complexity of the discipline itself and the lack of awareness of existing MDO technologies, software and implementation strategies. This paper introduces a potential measure to lower the accessibility level of MDO: an MDO advisory system supported by knowledge-based technologies. This MDO advisory system will enable the user to first specify an MDO problem and it will return a ranked list of suitable MDO architectures, based on the characteristics of the specified problem, to the user. Additionally, the advisory system will support the user during the implementation of the suggested optimization approach by providing (links to) specific documentation and, most of all, take care of some of the software intensive operations required to integrate the selected architecture in a commercial MDO framework. This paper provides an overall discussion of the envisioned advisory system and focuses on the knowledge-based technologies, and the implications of their implementation. These technologies make up the backbone of the envisioned advisory system, including a domain-specific ontology for MDO and a reasoning engine to provide the required reasoning capabilities for advice. Preliminary results include an ontology to enable the use of monolithic and distributed MDO architectures/problems and an extension of the reasoning functionalities of an open-source reasoner. Finally, a combination of a rule engine and query mechanism is proposed to support the use of rules on top of the ontology.","MDO; ontologies; knowledge-based technologies; semantic web technologies; OWL; design methodologies; automation","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:8380c266-131e-48b0-bba4-21e3505a3382","http://resolver.tudelft.nl/uuid:8380c266-131e-48b0-bba4-21e3505a3382","Multiple Wake Vortex Lattice Method for Airborne Wind Energy Membrane-Wing Kites (poster)","Leuthold, R.; De Oliveira Andrade, G.L.; Schmehl, R.","","2015","","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:6dc5f0fd-0faf-4006-baeb-713f491ad5ba","http://resolver.tudelft.nl/uuid:6dc5f0fd-0faf-4006-baeb-713f491ad5ba","Using iterated extended Kalman Filtering for estimation of a hexapod flight simulator motion state","Miletovic, I.; Pool, D.M.; Stroosma, O.; Chu, Q.P.; van Paassen, M.M.","","2015","The six degrees-of-freedom Stewart platform, or hexapod, is in widespread use in the flight simulation industry for the generation of motion cues that are representative of those experienced in actual flight. For closed-loop control of such motion platforms, but also to be able to objectively assess the quality of the generated simulator motion, accurate measurement of the kinematic state of the motion platform is required. In current practice, the inference of such knowledge relies mainly on the isolated use of actuator length measurements and on, in certain cases, on-platform inertial sensors. The purpose of the current work is to extend a previously proposed and conceptually superior method, based on a tightly-coupled fusion of measurements provided by these sensors using the Iterated Extended Kalman Filter (IEKF). Results from computer simulations indicate that the IEKF has difficulty in converging to the true system state of a six degrees-of-freedom Stewart platform. This is because of the considerable increase in nonlinearity of the platform kinematics. Future research should therefore focus on the application of more advanced filters. In addition, further extension of the sensor fusion scheme using other types of sensors is investigated.","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:ceeec0b5-e715-40e2-9ea9-0274acec9904","http://resolver.tudelft.nl/uuid:ceeec0b5-e715-40e2-9ea9-0274acec9904","Using digital homework assignments, the case of performance engineering","Ghijs, S.S.A.; Kamp, A.; Santema, S.C.","","2008","","","en","conference paper","AACE, Chesapeake","","","","","","","","Aerospace Engineering","","","","",""
"uuid:20fef8a5-a64b-4eff-9b92-730ccdf6a634","http://resolver.tudelft.nl/uuid:20fef8a5-a64b-4eff-9b92-730ccdf6a634","Ultrasonic welding of thermoplastic composites with flat energy directors: Influence of the thickness of the energy director on the welding process","Palardy, G.; Fernandez Villegas, I.","","2015","This paper presents a detailed experimental examination of the influence of the thickness of flat energy directors (ED) on the ultrasonic welding (USW) process for carbon fibre/polyetherimide composites. Three thicknesses of flat ED were compared: 0.06 mm, 0.25 mm and 0.50 mm. Power and displacement data for 0.06 mm-thick EDs did not clearly show the stages of the process and the location of the optimum for best weld quality. Consequently, an investigation of samples welded at different stages in the welding process had to be performed. For 0.06 mm-thick EDs, the optimum was determined to occur at the beginning of the downward displacement of the sonotrode in the vibration phase. The output parameters at the optimum conditions for all thicknesses were compared. Average lap shear strength was found to be lowest for 0.06 mm-thick EDs. Based on the analysis of the fracture surfaces, resin flakes and voids were observed when using the thinnest energy directors, indicating thermal degradation. These observations suggest that thin energy directors are not as efficient as thicker EDs (i.e. 0.25 mm) to achieve preferential heat generation at the weld line, leading to less consistent weld quality.","thermoplastic composites; ultrasonic welding; energy directors; joining","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:7257d901-e580-4968-a0d4-514850b3d5df","http://resolver.tudelft.nl/uuid:7257d901-e580-4968-a0d4-514850b3d5df","A comparison between modeled and measured high frequency bottom backscattering","Simons, D.G.; Snellen, M.","","2008","","","en","conference paper","Société Française d'Acoustique","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:75d62074-dbff-48f8-96be-813fe78c5786","http://resolver.tudelft.nl/uuid:75d62074-dbff-48f8-96be-813fe78c5786","PIV-based study of a cylindrical roughness element in a hypersonic laminar-boundary layer","Avallone, F.; Ragni, D.; Schrijer, F.F.J.; Scarano, F.; Cardone, G.","","2015","In this study, the mean flow organization in the symmetry plane of the recirculation region ahead of a cylindrical roughness element immersed in an incoming laminar boundary layer at Mach number equal to 6.5 is investigated. The flow topology is inspected with planar particle image velocimetry (PIV), InfraRed (IR) Thermography and Schlieren flow visualization. The flow approaching the roughness element forms a main recirculation region ahead of the cylinder leading edge. The reattachment vortex is the responsible of a heat flux local peak in front of the protuberance. Secondary, a more complex system of vortices is observed upstream of the protuberance, which also corresponds to the local maximum of turbulent kinetic energy and wall heat transfer.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:a5c3103d-e20d-4a3c-9eb6-2dc7b2874969","http://resolver.tudelft.nl/uuid:a5c3103d-e20d-4a3c-9eb6-2dc7b2874969","Multi-sensor evaluation of a wooden panel painting using terahertz imaging and shearography","Groves, R.M.; Pradarutti, B.; Kouloumpi, E.; Osten, W.; Notni, G.","","2009","Cultural heritage objects are increasingly being investigated using advanced non-destructive optical measurement techniques. Holographic and speckle interferometry based instrumentation allow dimensional measurement of objects at the tens of nanometer scale. For the structural diagnostics of artwork, double-exposure techniques are often used to locate defects, delaminations, voids and other structural features. Shearography is a speckle interferometry configuration that uses a close-to-common-path shearing interferometer configuration to give a direct sensitivity to displacement gradient at the object surface. This configuration is particularly useful for measurements outside the optical laboratory, as the stability requirements are much reduced compared with holography techniques. Terahertz imaging is a new category of sensor, used to investigate materials using electromagnetic radiation in the 0.1 to 10 THz frequency range. At these frequencies many materials become semi-transparent, so bulk structural diagnostics can be performed. Typically terahertz imaging is performed using a scanning pixel, or multi-pixel, sensor. In this manuscript shearography is first used to identify areas of interest of possible structural anomalies in the artwork. These regions of interest are then studied in more detail using the terahertz imaging instrument. Together the two instruments provide an analysis of both the surface and bulk structural features. The approach is demonstrated experimentally using a wooden panel painting.","terahertz imaging; shearography; art conservation; structural diagnostics","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Structural Integrity & Engineering Mechanics","","","",""
"uuid:3c29b2a0-687a-459b-92c3-fcdf8dd86868","http://resolver.tudelft.nl/uuid:3c29b2a0-687a-459b-92c3-fcdf8dd86868","A great and agonizing experience; interview with MSc student Samo Simonian and dr.i. Christos Kassapoglou","Coosemans, J.; Srongprapa, P.","","2012","","","en","conference paper","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:568ae092-34a7-4b35-b65e-3fc7691dfd9d","http://resolver.tudelft.nl/uuid:568ae092-34a7-4b35-b65e-3fc7691dfd9d","How do pilots perceive time-to-contact from the ground surface: Results of a visual simulation experiment","Pleijsant, J.M.; Mulder, M.; Van Der Vaart, J.C.; Van Wieringen, P.C.W.","","1996","","","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d08cac69-d4da-48e2-849f-067c3ab48096","http://resolver.tudelft.nl/uuid:d08cac69-d4da-48e2-849f-067c3ab48096","Knowledge based engineering to support aircraft multidisciplinary design and optimisation","La Rocca, G.; Van Tooren, M.J.L.","","2008","","KBE; MDO; Aircraft Design; Multi Model Generator; High Level Primitives","en","conference paper","Optimage Ltd.","","","","","","","","Aerospace Engineering","","","","",""
"uuid:cd7d84b0-cd38-47da-b525-9eb47a3b2926","http://resolver.tudelft.nl/uuid:cd7d84b0-cd38-47da-b525-9eb47a3b2926","Fast maximum likelihood estimate of the Kriging correlation range in the frequency domain","De Baar, J.H.S.; Dwight, R.P.; Bijl, H.","","2011","We apply Ordinary Kriging to predict 75,000 terrain survey data from a randomly sampled subset of < 2500 observations. Since such a Kriging prediction requires a considerable amount of CPU time, we aim to reduce its computational cost. In a conventional approach, the cost of the Kriging analysis would be dominated by the optimization routine required to find the maximum likelihood, which provides an estimate of the correlation ranges. We propose to transform the optimization problem to the frequency domain, such that the cost of the optimization is now dominated by that of a single Fourier transform required to find the power spectrum of the observations, as a result of which the computational cost is now virtually independent of the number of optimization steps. For the present application, we find that the proposed approach is as accurate as the conventional approach for a sample size of 100 or more. The CPU time increases with the number of optimization steps for the conventional approach, while it is virtually constant for the proposed approach.","","en","conference paper","IAMG","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:7b6b95d2-076e-4f38-b167-879253805263","http://resolver.tudelft.nl/uuid:7b6b95d2-076e-4f38-b167-879253805263","Wind turbine and actuator disc wake: Two experimental campaigns","Lignarolo, L.; Ragni, D.; Simao Ferreira, C.J.; van Bussel, G.J.W.","","2015","The present paper is the summary of 3 years of research on the wake aerodynamics of horizontal axis wind turbine at Delft University of Technology, the Netherlands. In particular, the main results and the conclusions of two experimental campaigns are collected. The underlying research question is: how do the near-wake turbulent flow structures affect the re-energising of the far wake and to what extend is the actuator disc assumption valid for the representation of the near wake dynamics? In the first experiments, stereo particle image velocimetry is used for analysing the turbulent velocity field in the near and transition wake of a small two-bladed wind turbine model. The results showed the important role of the tip-vortex helix instability (leapfrogging) in the mixing process and in the re-energising of the wake. The tip-vortex instability and breakdown, in fact, give rise to a more efficient turbulent mixing. In the second campaign, the same measurement technique is used for acquiring data in the near wake of the wind turbine model and in the near wake of a porous disc, emulating the numerical actuator disc. The results show a good match velocity fields between wind turbine and actuator disc, but show a different turbulence intensity and turbulent mixing. The analysis suggest the possibility to extend the use of the actuator disc model in numerical simulation until the very near wake, provided that the turbulent mixing is correctly represented.","Tip-Vortex Instability; Wind Turbine Wake; PIV Experiments; Wake Turbulence; Actuator Disc","en","conference paper","UFRGS","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:d63eab6c-4cab-4ab2-ac14-d13d91837443","http://resolver.tudelft.nl/uuid:d63eab6c-4cab-4ab2-ac14-d13d91837443","Assessment of aircraft noise sources variability using an acoustic camera","Snellen, M.; Merino Martinez, R.; Simons, D.G.","","2015","Noise assessment around airports is hampered due to the observed large variability in noise levels for fly-overs of the same aircraft type, which is not considered by the current models. This paper assumes that the noise variability is due to variations in the aircraft emitted noise, neglecting the effect of the variable atmosphere, as previous work showed that its contribution is maximally 2 dB. In order to quantify and investigate the variability of noise levels during aircraft fly-overs, 115 measurements of noise of landing aircraft were taken using a 32 microphone array. The noise levels from Boeing 737 fly-overs were analyzed and the noise level variability was determined to be approximately 16 dB. After determining the engine settings from the spectrograms, it was found that variations on the engine settings explain over 55% of the observed total noise variation. In addition, by performing beamforming on the acoustic data, it was confirmed that airframe noise (from the landing gear and deployed flaps) is dominant for several frequencies, especially for modern aircraft.","","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:3f03c6bf-861e-4ee7-ba25-9a024874addc","http://resolver.tudelft.nl/uuid:3f03c6bf-861e-4ee7-ba25-9a024874addc","Experimental capsule afterbody flow investigation","Schrijer, F.F.J.; Mignoli, G.; Scarano, F.; Walpot, L.M.G.F.M.","","2008","","supersonic flow; afterbody flow; particle image velocimetry","en","conference paper","ESA-ESTEC","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5e59e0d9-e05a-4812-a765-f1c07e0d2120","http://resolver.tudelft.nl/uuid:5e59e0d9-e05a-4812-a765-f1c07e0d2120","Effects of Leading-Edge Radius on Aerodynamic Characteristics of 50º Delta Wings","Verhaagen, N.G.","","2010","The study focuses on the effects of the leading-edge radius on the flow over 50º swept delta wing models. Three models were tested, one model having a sharp leading edge and the other two having a semi-circular leading edge of different radius. The vortical flow on and off the surface of the models was investigated using an oil-flow visualization and a Stereo Particle Image Velocimetry (SPIV) technique. The leading-edge radius is shown to affect the size and location of the vortices and also the vortex bursting location over the models. As a result of this, the leadingedge radius also affects the forces and moment acting on a 50o delta wing.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:fbc0a101-7bef-442b-b015-1e789bc31a70","http://resolver.tudelft.nl/uuid:fbc0a101-7bef-442b-b015-1e789bc31a70","Control Space Analysis of Three-Degree Decelerating Approaches at Amsterdam Airport Schiphol","De Jong, P.M.A.; In 't Veld, A.C.; De Leege, A.M.P.; Van Paassen, M.M.; Mulder, M.","","2010","Amsterdam Schiphol Airport currently uses a Continuous Descent Approach during night time operations only, due to reduced runway capacity caused by unpredictable individual aircraft behavior. The Three-Degree Decelerating Approach (TDDA) has been developed to increase predictability and runway capacity by switching the sepa- ration task from Air Traffic Control to the pilot on board the aircraft. The research described in this paper identifies the factors that influence the control space of aircraft performing a TDDA in a real-life setting. Control space is defined as the difference between the maximum and minimum duration to perform the TDDA. Using different control strategies, a fast approach or slow approach can be flown. A fast-time simulation tool was built to perform simulations with different aircraft types, initial weights, wind speeds and directions. Preliminary simulations indicate that a flap scheduler is needed to optimize control space, and the flap scheduling algorithm was enhanced to find optimal flap schedules for all wind conditions. The results of these simulations show that the influence of wind direction depends on aircraft aerodynamic characteristics, which mainly depend on the drag characteristics of the aircraft and aircraft weight. Furthermore, the results can be used to determine whether a TDDA can be executed using different aircraft and under different wind conditions.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:62601330-f4d2-422f-9b45-21c073aa828b","http://resolver.tudelft.nl/uuid:62601330-f4d2-422f-9b45-21c073aa828b","Wing flexibility effects in clap-and-fling","Percin, M.; Hu, Y.; Van Oudheusden, B.W.; Remes, B.; Scarano, F.","","2011","The work explores the use of time-resolved tomographic PIV measurements to study a flapping-wing model, the related vortex generation mechanisms and the effect of wing flexibility on the clap-and-fling movement in particular. An experimental setup is designed and realized in a water tank by use of a single wing model and a mirror plate to simulate the wing interaction that is involved in clap-and-fling motion. The wing model used in the experiments has the same planform with the DelFly II wings and consists of a rigid leading edge and an isotropic polyester film. The thickness of the polyester film was changed in order to investigate the influence of flexibility. A similarity analysis based on the two-dimensional dynamic beam equation was performed to compare aeroelastic characteristics of flapping-wing motion in-air and in-water conditions. Based on the experimental results, the evolution of vortical structures during the clap-and-peel motion is explained. The general effects of flexibility on vortex formations and interactions are discussed. It was observed that the flexibility affects the behavior and orientation of the vortices in relation to the deformation of the wing and interaction with the mirror plate.","flapping wing; Micro Air Vehicle; Particle Image Velocimetry","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:295b53d2-832b-453e-bfb0-f3449b30c563","http://resolver.tudelft.nl/uuid:295b53d2-832b-453e-bfb0-f3449b30c563","Development and implementation of knowledge-based design process primitives","Schut, E.J.; van Tooren, M.J.L.","","2008","","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1d527d12-7168-4dc3-bdd5-d5991fb4c514","http://resolver.tudelft.nl/uuid:1d527d12-7168-4dc3-bdd5-d5991fb4c514","Inverting for bottom parameters in shallow-water soft sediment environments using MBES backscatter strength","Siemes, K.; Snellen, M.; Simons, D.G.; Hermand, J.P.","","2009","Shallow water naval operations require detailed knowledge of the environmental properties. In addition to parameters such as water depth, knowledge about the sediment properties is of high importance for a wide range of operations. In this context, the MREA BP'07 experiment was carried out in the Mediterranean Sea in 2007. Measurements employed a large set of sensors, thereby providing all information required to fully describe the environment. This paper focuses on multibeam echosounder (MBES) measurements, which were taken not only to provide information about the water depths, but also to provide the backscatter strength as a function of angle. These backscatter data are employed to infer sediment parameters. To this end, a comparison of measured and modeled backscatter strengths is conducted. Use is made of a model that accounts for both scattering at the water-sediment interface and scattering and scattering at the inhomogeneities in the sediment, i.e. volume scattering. In practice, the measured backscatter strength values are affected by the imperfect MBES calibration. This impedes a direct model-data comparison, unless the effects of miscalibration are eliminated. Therefore, a calibration curve is derived by optimizing spectral strength and volume parameter, according to known mean grain sizes at bottom grab positions. After having corrected the measured backscatter strength for these systematic effects, inversions are carried out to estimate the sediment parameters (grain size, spectral strength, and volume parameter) at various locations in the research area.","backscattering; seafloor classification; inversion; multibeam echosounder","en","conference paper","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:1df6a732-0863-43f8-b5ed-ca09aa287f47","http://resolver.tudelft.nl/uuid:1df6a732-0863-43f8-b5ed-ca09aa287f47","FSI of Inflatable Kite Wings (poster)","Rajan, N.K.; Vire, A.; Schmehl, R.; Van Bussel, G.J.W.","","2015","A novel fluid-structure interaction (FSI) simulation framework is being developed at the KitePower group of TU Delft. Developing an FSI simulator suitable for the kite problem has to take into account the following factors.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:5a8cbf12-bdf4-4903-bbca-cab8b06e2ea1","http://resolver.tudelft.nl/uuid:5a8cbf12-bdf4-4903-bbca-cab8b06e2ea1","The Delfi-n3Xt nanosatellite: Space weather research and qualification of microtechnology","De Jong, S.; Maddox, E.; Vollmuller, G.J.; Schuurbiers, C.A.H.; Van Swaaij, R.A.C.M.M.; Ubbels, W.J.; Hamann, R.J.","","2008","The Delfi-C3 nanosatellite successor, Delfi-n3Xt, is currently under development at Delft University of Technology and scheduled for launch in the first half of 2010. This improved three-unit CubeSat platform allows novel technology qualification for future small satellites and innovative scientific research. The platform is improved by implementing a high-speed downlink, three-axis stabilization and a single-point-failure free implementation of batteries in the electrical power subsystem. Apart from giving a description of the three main advancements, this paper also gives an overview of the five payloads: A microsystems technology based cool gas micropropulsion module, a multifunctional particle spectrometer, a set of hydrogenated amorphous silicon solar cells, an efficient transceiver module for nanosatellites, and a memory unit based on low-cost commercial grade ash memory cards with innovative radiation protection electronics. Although the accommodation of the five payloads in a nanosatellite of only (10 x 10 x 34) cm is ambitious, this paper shows feasibility and proves that nanosatellites are powerful instruments for the qualification of novel technology and innovative scientific research.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:cb5899fd-4486-47b3-9484-952b1b5a23dc","http://resolver.tudelft.nl/uuid:cb5899fd-4486-47b3-9484-952b1b5a23dc","High frequency scattering measurements for mussel bed characterisation","Snellen, M.; Simons, D.G.; Riethmueller, R.","","2008","","","en","conference paper","Société Française d'Acoustique","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:bd9dabe4-fd52-4d3d-bf14-8a4968c796a9","http://resolver.tudelft.nl/uuid:bd9dabe4-fd52-4d3d-bf14-8a4968c796a9","Optimizing terrestrial laser scanning measurement set-up","Soudarissanane, S.S.; Lindenbergh, R.C.","","2011","One of the main applications of the terrestrial laser scanner is the visualization, modeling and monitoring of man-made structures like buildings. Especially surveying applications require on one hand a quickly obtainable, high resolution point cloud but also need observations with a known and well described quality. To obtain a 3D point cloud, the scene is scanned from different positions around the considered object. The scanning geometry plays an important role in the quality of the resulting point cloud. The ideal set-up for scanning a surface of an object is to position the laser scanner in such a way that the laser beam is near perpendicular to the surface. Due to scanning conditions, such an ideal set-up is in practice not possible. The different incidence angles and ranges of the laser beam on the surface result in 3D points of varying quality. The stand-point of the scanner that gives the best accuracy is generally not known. Using an optimal stand-point of the laser scanner on a scene will improve the quality of individual point measurements and results in a more uniform registered point cloud. The design of an optimum measurement setup is defined such that the optimum stand-points are identified to fulfill predefined quality requirements and to ensure a complete spatial coverage. The additional incidence angle and range constraints on the visibility from a view point ensure that individual scans are not affected by bad scanning geometry effects. A complex and large room that would normally require five view point to be fully covered, would require nineteen view points to obtain full coverage under the range and incidence angle constraints.","laser scanning; point cloud; error; noise level; accuracy; optimal stand-point","en","conference paper","International Society for Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:16083bb3-d10b-4462-9112-2f85d2df66b1","http://resolver.tudelft.nl/uuid:16083bb3-d10b-4462-9112-2f85d2df66b1","Pressure adaptive honeycomb: A new adaptive structure for aerospace applications","Vos, R.; Barrett, R.","","2010","A new type of adaptive structure is presented that relies on pressurized honeycomb cells that extent a significant length with respect to the plane of the hexagons. By varying the pressure inside each of the cells, the stiffness can be altered. A variable stiffness in combination with an externally applied force field results in a fully embedded pressure adaptive actuator that can yield strains well beyond the state-of-the-art in adaptive materials. The stiffness change as a function of the pressure is modeled by assigning an equivalent material stiffness to the honeycomb walls that accounts for both the inherent material stiffness as the pressure-induced stiffness. A finite element analysis of a beam structure that relies on this model is shown to correlate well to experimental results of a three-point bend test. To demonstrate the concept of embedded pressure adaptive honeycomb, an wind tunnel test article with adaptive flap has been constructed and tested in a low speed wind tunnel. It has been proven that by varying the cell pressure the flap changed its geometry and subsequently altered the lift coefficient.","pressure; adaptive; honeycomb; morphing aircraft; pneumatic; inflatable","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","System Engineering & Aircraft Design","","","",""
"uuid:07d2ed4e-14bc-4808-95cd-c86de92e2da9","http://resolver.tudelft.nl/uuid:07d2ed4e-14bc-4808-95cd-c86de92e2da9","Feasilization of a structural wing design problem","Schut, E.J.; Van Tooren, M.J.L.; Berends, J.P.T.J.","","2008","","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","","","","",""
"uuid:02c8225b-1ab9-464d-ac3a-1628999f2250","http://resolver.tudelft.nl/uuid:02c8225b-1ab9-464d-ac3a-1628999f2250","Arrival Trajectory Optimization for Passenger Aircraft using Genetic Algorithms","Yu, H.; Mulder, J.A.","","2012","This work concentrates on the development of an optimization technique which is capable of minimizing the noise impact of an arriving aircraft by optimizing its flight trajectory. Actions needed from pilots to gradually establish the landing configuration are considered because it is expected that the pilot workload throughout this phase should be remained or even reduced compared with the current standard arrival procedures. Therefore, the conventional point-mass equations of motion are reformulated in such a way that the variations of the aerodynamic performance of the aircraft of different configurations can be easily taken into account. A set of independent state variables are chosen to be parameterized with Bernstein polynomials in order to convert the infinite-dimensional optimal control problem into a finite-dimensional parametric optimization problem. The number of awakenings is selected as the performance index and finally written into a function of the parameters introduced by the parameterization process. Genetic algorithms are employed to optimize these parameters within a search domain in order to minimize the number of awakenings while satisfying all constraints on both state and control variables. A number of numerical examples, for a Boeing 747-400 aircraft arriving at an airport with different population distribution situations, are provided to demonstrate the feasibility and effectiveness of the proposed optimization technique. Without loss of generality, this particular technique is also able to deal with a departing aircraft since most of the models are built into replaceable modules.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:b83d2f76-e730-4825-84c8-77a7643102a3","http://resolver.tudelft.nl/uuid:b83d2f76-e730-4825-84c8-77a7643102a3","Adjoint Optimization of a Wing Using the CSRT Method","Straathof, M.H.; Van Tooren, M.J.L.","","2011","This paper will demonstrate the potential of the Class-Shape-Refinement-Transformation (CSRT) method for aerodynamically optimizing three-dimensional surfaces. The CSRT method was coupled to an in-house Euler solver and this combination was used in an optimization framework to optimize the ONERA M6 wing in transonic conditions. The gradients of the flow variables with respect to the design parameters were computed using an adjoint solver integrated in the Euler code. The optimization was performed by a trust region reflective algorithm. A two-step approach was used to optimize the wing. First, a “general” optimization was done using the Bernstein coefficients of the shape function. Second, a “regional” refinement was performed using the B-spline coefficients of the refinement function. It was shown that using this strategy a considerable improvement of the lift-to-drag ratio of 22 % could be achieved. This result proves that an adjoint optimization using the CSRT method is an effective way to improve transonic wing performance.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:8f4c87ce-fdea-48cd-834b-a30f47c4fe93","http://resolver.tudelft.nl/uuid:8f4c87ce-fdea-48cd-834b-a30f47c4fe93","Effect of Performing a Boundary-Avoidance Tracking Task on the Perception of Coherence Between Visual and Inertial Cues","Valente Pais, A.R.; Van Paassen, M.M.; Mulder, M.; Wentink, M.","","2011","During flight simulation, the inertial and visual stimuli provided to the pilot differ considerably. For successful design of motion cueing algorithms it is necessary to gather knowledge on how pilots perceive the difference between visual and inertial cues. Some of the work done on this topic has concentrated on the concept of coherence zone. A coherence zone represents a range of inertial motion amplitudes, which although not being a match with the visual motion, are still perceived by humans as one realistic, coherent movement. To extend the knowledge on coherence zones an experiment was performed that tested the yaw motion coherence zone limits at two frequencies during passive and active situations. Subjects were required to perform a boundary-avoidance task as a mean to decrease the attention given to the perception task. This decrease in attention was thought to cause a widening of the perceived coherence zones. The boundary-avoidance tracking task had two levels of difficulty. The measured coherence zones did not change significantly with the addition of the control task. These results imply that unlike motion perception thresholds, coherence zones are little influenced by decreased levels of attention. This being true, for a range of tasks, such as supervisory tasks or procedural training in a flight simulator, pilot acceptance of the inertial cues might be measured in a passive manner and directly applied to the active scenario.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:1644517b-a8b9-4a05-b73c-cbadc5145ae4","http://resolver.tudelft.nl/uuid:1644517b-a8b9-4a05-b73c-cbadc5145ae4","Implementing reliability, availability, maintainability and supportability RAMS for the MRO industry: A case study at European Airlines","Ghobbar, A.A.","","2008","","reliability; availability; maintainability and supportability; aircraft maintenance","en","conference paper","ESReDA European Safety Reliability and Data Association, San Sebastián","","","","","","","","Aerospace Engineering","","","","",""
"uuid:126ced2c-0466-46b5-b4a0-ac3f17ccbe1b","http://resolver.tudelft.nl/uuid:126ced2c-0466-46b5-b4a0-ac3f17ccbe1b","Modelling and observing the 8.8 Chile and 9.0 Japan earthquakes using GOCE","Broerse, D.B.T.; Visser, P.N.A.M.; Bouman, J.; Fuchs, M.; Vermeersen, L.L.A.; Schmidt, M.","","2011","Large earthquakes do not only heavily deform the crust in the vicinity of the fault, they also change the gravity field of the area affected by the earthquake due to mass redistribution in the upper layers of the Earth. Besides that, for sub-oceanic earthquakes deformation of the ocean floor causes relative sea-level changes and mass redistribution of water that has again a significant effect on the gravity field. Such a sub-oceanic earthquake occurred on 27 February 2010 in central Chili with a magnitude of Mw 8.8 and on 11 March 2011 with a magnitude of Mw 9.0 near the east coast of Honshu, Japan. This makes both a potential candidate for detecting the co-seismic gravity changes in the GOCE gradiometer data. We will assess the detectability of gravity field changes in the GOCE gravity gradients by modelling these earthquakes using a forward model as well as taking differences of of GOCE data before and after the respective earthquakes.","GOCE; co-seismic deformation; Maule 8.8 earthquake; Tohoku 9.0 earthquake; time variable gravity","en","conference paper","European Space Agency (ESA)","","","","","","","","Aerospace Engineering","Astrodynamics & Satellite Systems","","","",""
"uuid:771c06f7-0930-470f-8ccd-17194fd23304","http://resolver.tudelft.nl/uuid:771c06f7-0930-470f-8ccd-17194fd23304","Stereo PIV measurements on circular and chevron synthetic jets","Crispo, C.M.; Greco, C.S.; Avallone, F.; Cardone, G.","","2015","Abstract.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:4947da9b-cf55-44f8-bd5d-94021815a34a","http://resolver.tudelft.nl/uuid:4947da9b-cf55-44f8-bd5d-94021815a34a","Positioning and applications for planet earth","Verhagen, S.; Retscher, G.; Santos, M.C.; Ding, X.L.; Gao, Y.; Jin, S.G.","","2009","GNSS, InSAR and LIDAR are identified as important techniques when it comes to monitoring and remote sensing of our planet Earth and its atmosphere. In fact, these techniques can be considered as key elements of the Global Geodetic Observing System. Examples of applications are: environmental monitoring; volcano monitoring, land slides, tectonic motion, deforming structures, atmosphere modeling, and ocean remote sensing. Hence, it concerns applications at local and regional scales, as well as at global scales. The main issues can be summarized as: need for a better understanding of processes, leading to better models; need for observational material; and adequate modeling techniques","","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:227aa603-01e6-4a86-8395-0dd53de5595a","http://resolver.tudelft.nl/uuid:227aa603-01e6-4a86-8395-0dd53de5595a","Simulation of automatic helicopter deck landings using nature inspired flight control and flight envelope protection","Voskuijl, M.; Walker, D.J.; Manimala, B.J.; Gubbels, A.W.","","2008","","","en","conference paper","Royal Aeronautical Society","","","","","","","","Aerospace Engineering","","","","",""
"uuid:112eb903-2b8e-4393-be16-c17c2fb1e7ac","http://resolver.tudelft.nl/uuid:112eb903-2b8e-4393-be16-c17c2fb1e7ac","Design of anisotropic composite shells using an isogeometric approach","Nagy, A.P.; Abdalla, M.M.; Gürdal, Z.","","2010","Thin-walled composite structures, typically modeled as Cosserat continua during the design phase, are of particular importance in aerospace and automotive applications. At the dawn of industrial scale adoption of advanced fibre placement technology, it became viable to better exploit the directional properties of composite materials. In the recent past, numerous researches were devoted to the design of shells with optimal anisotropy. In the present work, combined stiffness tailoring and shape optimal design is proposed that is naturally facilitated in a non-uniform rational B-spline based isogeometric approach. Spatial variation of stiffness properties is parameterised by means of lamination parameters and the thickness of the shell. Shape changes are easily achieved by modifying selected control point co-ordinates and weights. The method of successive approximations has been employed to solve the optimisation problem. The formulation is separable in terms of sizing variables, however, separability of the shape design problem is not enforced. The design framework is verified through selected compliance minimisation problems.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:9e4c03f8-9b13-45c1-8043-c74b14faadc0","http://resolver.tudelft.nl/uuid:9e4c03f8-9b13-45c1-8043-c74b14faadc0","Fragile! handle with care! The effects of vibrations on pastels in transport (poster)","Sauvage, L.L.F.; Martinez, M.J.; Wei, W.; Van Leeuwen, I.","","2015","","","en","conference paper","TU Delft / Rijksmuseum","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:0f199cc9-ae1f-43ef-8dd7-3c06083724e4","http://resolver.tudelft.nl/uuid:0f199cc9-ae1f-43ef-8dd7-3c06083724e4","Very long baseline interferometry with the SKA","Paragi, Z.; Godfrey, L.; Gurvits, L.; et al ","","2014","Adding VLBI capability to the SKA arrays will greatly broaden the science of the SKA, and is feasible within the current specifications. SKA-VLBI can be initially implemented by providing phased-array outputs for SKA1-MID and SKA1-SUR and using these extremely sensitive stations with other radio telescopes, and in SKA2 by realising a distributed configuration providing baselines up to thousands of km, merging it with existing VLBI networks. The motivation for and the possible realization of SKA-VLBI is described in this paper.","","en","conference paper","POS","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:59062225-df81-4965-9ff9-0a18c8491415","http://resolver.tudelft.nl/uuid:59062225-df81-4965-9ff9-0a18c8491415","Environmental Impact Evaluation of Aircraft at System-of-Systems Level","Schroijen, M.J.T.; Van Tooren, M.J.L.; Voskuijl, M.; Curran, R.","","2011","Next generations of civil transport aircraft will need to be evaluated not only against their behaviour as an aircraft system but also as a part of the larger air transport system. In addition to this are the sustainability issues related to for instance noise and emissions, represented by environmental impact. Both issues mandate the incorporation of complex stakeholder behaviour in the design and evaluation of future aircraft. A framework is proposed in extension of existing Design and Engineering Engines to perform such evaluations. For this extension a combination of agent based modelling and simulation approach, value engineering and multi-level optimization is suggested to quantitatively implement quality function deployment. As an illustration of the complexity in evaluating new aircraft concepts, the Prandtl Plane study case is used. From this study case it is found that, when evaluated using the current DEE, the Prandtl Plane shows a potential for alternative use at systems level. But no conclusion can be drawn on the environmental impact effect on the air transport system without addressing the system-of-systems considerations. This includes the unknown stakeholder response with respect to the new opportunities provided by the Prandtl Plane. One of the great challenges for future design is the increasing complexity, not only in the proposed solutions, e.g. Prandtl Plane, but also in the measures of desirability, e.g. global emissions. This requires the integrated approach addressing the complexities at both system-of-systems and system level, proposed in extension to the current design and engineering engine.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:caddc032-be69-4073-9a50-72d51a9c09b2","http://resolver.tudelft.nl/uuid:caddc032-be69-4073-9a50-72d51a9c09b2","Strain characterization of embedded aerospace smart materials using shearography","Anisimov, A.; Muller, B.; Sinke, J.; Groves, R.M.","","2015","The development of smart materials for embedding in aerospace composites provides enhanced functionality for future aircraft structures. Critical flight conditions like icing of the leading edges can affect the aircraft functionality and controllability. Hence, anti-icing and de-icing capabilities are used. In case of leading edges made of fibre metal laminates heater elements can be embedded between composite layers. However this local heating causes strains and stresses in the structure due to the different thermal expansion coefficients of the different laminated materials. In order to characterize the structural behaviour during thermal loading full-field strain and shape measurement can be used. In this research, a shearography instrument with three spatially-distributed shearing cameras is used to measure surface displacement gradients which give a quantitative estimation of the in- and out-of-plane surface strain components. For the experimental part, two GLARE (Glass Laminate Aluminum Reinforced Epoxy) specimens with six different embedded copper heater elements were manufactured: two copper mesh shapes (straight and S-shape), three connection techniques (soldered, spot welded and overlapped) and one straight heater element with delaminations. The surface strain behaviour of the specimens due to thermal loading was measured and analysed. The comparison of the connection techniques of heater element parts showed that the overlapped onnection has the smallest effect on the surface strain distribution. Furthermore, the possibility of defect detection and defect depth characterisation close to the heater elements was also investigated.","multicomponent shearography; strain measurement; defect depth characterisation; fibre metal laminates; GLARE; embedded heater elements; anti-icing; de-icing","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:57e2f668-bedc-4e91-9431-593944b659ce","http://resolver.tudelft.nl/uuid:57e2f668-bedc-4e91-9431-593944b659ce","Three-dimensional wake reconstruction of a flapping-wing MAV using a Kriging regression technique","Percin, M.; De Baar, J.H.S.; Van Oudheusden, B.W.; Dwight, R.P.","","2013","The work explores the three-dimensional unsteady wake of a flapping-wing Micro Air Vehicle (MAV) ‘DelFly II’, applying a Kriging regression technique for the spatial regression of time-resolved Stereoscopic Particle Image Velocimetry (Stereo-PIV) data. In the view of limited number of measurement planes, the particular objective of the regression is to provide an accurate volumetric representation of the measurement domain on a spatial grid that is much finer than the spacing between the measurement planes. A unique feature of the current study is the incorporation of a statistical error model in the Kriging regression process as an estimate of the local measurement uncertainty of the PIV measurements. The performance of the Kriging regression technique with local error estimates is evaluated based on direct comparisons to measurement data. As a final result of the regression, three-dimensional vortical structures are reconstructed and it is shown that each of two wings generates separate vortex loops and sheds two trailing edge vortices during the downstroke phase. On the other hand, the structures of upper and lower wings occasionally interact with each other during the upstroke phase. Wake structure displays major differences in terms of vortex formations for different reduced frequencies.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:9ba552be-134e-4fbe-88ac-8839f5ce3a4b","http://resolver.tudelft.nl/uuid:9ba552be-134e-4fbe-88ac-8839f5ce3a4b","Towards self-healing creep resistant steels","Van der Zwaag, S.; Zhang, S.; Fang, H.; Bruck, E.; Van Dijk, N.H.","","2016","We report the main findings of our work on the behaviour of binary Fe-Cu and Fe-Au model alloys designed to explore routes to create new creep resistant steels having an in-built ability to autonomously fill creep induced porosity at grain boundaries. The alloying elements were selected on the basis of their ability to be brought in supersaturation, their limited or even absent tendency to form immobile intermetallic compounds and their affinity to segregate to free surfaces. The model alloys were creep loaded to failure at various stress values at a fixed temperature of 550 0C. As a result of creep loading, grain boundary cavities developed which were either fully or partially filled by the alloying element explored. The degree of pore filling was found to depend on the alloying element, the stress level and the orientation of the residing grain boundary with respect to the applied load. The clearest examples of full or partial pore filling were observed for the Fe-Au system. In addition to pore filling, extensive precipitate formation was observed in the Fe-Cu alloys.","creep damage; pore filling; self-healing; model alloys","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:3483724d-ab48-41b9-95c0-0f6bbbd99675","http://resolver.tudelft.nl/uuid:3483724d-ab48-41b9-95c0-0f6bbbd99675","3, 2, 1, Launch!","De Kat, R.; Saunders-Smits, G.N.","","2009","It is important that young people who chose to pursue a degree in engineering stick with their choice. Unfortunately students often loose their motivation during their first year. This paper gives an example of how the Faculty of Aerospace Engineering of Delft University in The Netherlands manages to keep a large number of freshmen motivated and at the same time acquaint them with the wonderful world of aerospace engineering through the design, build, launch and analysis of PET bottle based water-rockets.","project education; water-rocket; aerospace engineering; freshmen retention","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:d296995d-a9f2-4a4f-8180-3efadee8cc78","http://resolver.tudelft.nl/uuid:d296995d-a9f2-4a4f-8180-3efadee8cc78","Lisa-S 2.8g autopilot for GPS-based flight of MAVs","Remes, B.D.W.; Esden-Tempski, P.; Van Tienen, F.; Smeur, E.; De Wagter, C.; De Croon, G.C.H.E.","","2014","Recent advances in sensor miniaturization have enabled the development of a miniaturized fully functional autopilot. In this article, the open hardware and open software Paparazzi-UAV Lisa-S micro autopilot is presented, weighing only 2.8 grams and measuring 2 by 2 centimeters. It incorporates 2-way telemetry with a ground station, a Spektrum DMS2/DSMX remote control, an IMU (Inertial Measurement Unit), a Magnetometer, a GPS module and a 32-bit 72 MHz processor for stabilization and navigation. As an illustration, the Lisa-S has been mounted on various miniature multi-rotors. Mounting it on a Ladybird quadrotor leads to a 8.5 by 8.5 cm system weighing 27 grams (excluding battery). Flight results are shown of the Ladybird performing autonomous GPS-based navigation missions outdoors.","Micro Air Vehicle; autopilot; open hardware; open source; light-weight; GPS; autonomous","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:b37b8968-f46e-4525-b222-4dea27f50284","http://resolver.tudelft.nl/uuid:b37b8968-f46e-4525-b222-4dea27f50284","Experimental investigation of three-dimensional flow structures in annular swirling jets","Percin, M.; Vanierschot, M.; Van Oudheusden, B.W.","","2015","Annular jet flows are of practical interest in view of their occurrence in many industrial applications in the context of bluff-body combustors [1]. They feature different complex flow characteristics despite their simple geometry: a central recirculation zone (CRZ) as a result of flow separation behind the centerbody and an outer (between the jet and the environment) and inner (between the jet and the central recirculation region) shear layer, which are both characterized by strong anisotropic turbulence [2]. The complexity of the flow is further enhanced by introducing swirl which leads to the formation of large zones of recirculation and large scale instabilities at certain swirl numbers, such as Vortex Breakdown or a Precessing Vortex Core (PVC) [3,4]. These large coherent structures have been well studied for round jets. However, in the case of annular jet flows, there is still a lot of work to do,especially regarding the interaction between the instabilities and the CRZ. The specific aim of this study is therefore to investigate the spatial and temporal characteristics of these three-dimensional flow fields by means of time-resolved Tomographic Particle Image Velocimetry measurements (Tomo-PIV). The time averaged flow field is found to be axisymmetric with a central recirculation bubble. However, looking at the transient features of the flow, a central vortex core precesses around the central axis and breaks up into a double helix when the flow becomes critical. This form of vortex breakdown is very rare and is exclusively reported in case of laminar jet flows.","","en","conference paper","University of Poitiers","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:f940adc4-cd3f-4561-9590-fbbcb82da8cb","http://resolver.tudelft.nl/uuid:f940adc4-cd3f-4561-9590-fbbcb82da8cb","Topology Design of Pressure Adaptive Honeycomb for a Morphing Fowler Flap","Scheepstra, J.; Vos, R.; Barrett, R.","","2011","A new method for designing a morphing Fowler flap based on pressure-adaptive honeycomb is detailed. Pressure adaptive honeycomb has been shown to be able to induce gross camber deformations in airfoil sections, such as a flap. However, due to the large amount of design variables the integration of the honeycomb as a distributed actuator in a flap structure has proven to be challenging. Therefore, a design tool is developed that can aid the designer in generating a honeycomb and flap topology that ensures two desired shapes under two distinct conditions: a cruise shape and a high-lift shape. This tool is based on a finite-element analysis of the pressure-adaptive honeycomb, where the honeycomb elements are reduced to simple rigid-bar elements connected by frictionless hinges. This tool is verified against analytical and experimental results. In the present implementation the honeycomb is attached to the upper skin of the flap, which itself introduces curvature in the aft flap section. An optimization algorithm calculates the exact thickness distribution of the skin that introduces the prescribed shape in high-lift conditions. By varying the pressure inside the honeycomb, the initial skin curvature distribution, or the honeycomb topology, the designer can evaluate how well the calculated shapes match the desired shapes in high-lift and cruise condition. This allows for a faster and more accurate topology designs that can ultimately enable an effective morphing solution to increase the maximum lift capability of Fowler flaps.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:fe8d2b88-f6b0-4844-8b89-d97904a660e8","http://resolver.tudelft.nl/uuid:fe8d2b88-f6b0-4844-8b89-d97904a660e8","How proper similitude principles could have improved our understanding about fatigue damage growth","Alderliesten, R.C.","","2015","This paper discusses similitude parameters for predicting fatigue damage growth, and demonstrates that proper principles exploiting the strain energy release could have improved our knowledge on fatigue damage growth. The paper demonstrates how the original Stress Intensity Factor concept introduced by Irwin has been introduced inconsistently for describing fatigue crack growth. Subsequently, it illustrates how this has led to misinterpretation of certain phenomena, like for example plasticity induced crack closure. Using proper similitude in agreement with the physics of observed fatigue damage phenomena, it is demonstrated how the average strain energy release over a single load cycle should relate to the crack surface extension in that same load cycle. The paper concludes with illustrating how phenomena like for example plasticity and fibre bridging in composites can be understood and quantified.","","en","conference paper","VTT Technical Research Centre of Finland","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:c69fc06d-aaa3-4151-bcd9-e31e61c1dcd2","http://resolver.tudelft.nl/uuid:c69fc06d-aaa3-4151-bcd9-e31e61c1dcd2","Tailoring for Strength of Steered-Fibre Composite Panels with Cutouts","Lopes, C.; Camanho, P.P.; Gürdal, Z.","","2010","The traditional approach to the problem of stress concentrations around cutouts in composite structures is to locally increase the laminate thickness in order to smooth out the stress peak. Often, this practice attracts more loads to the cutout region besides increasing part weight. A more effective solution is to avoid the stress concentrations altogether by using fibre-steered laminates. The production of composites in this format is practical nowadays due to capabilities of advanced fibre-placement technology. This paper shows that it is possible to design and manufacture composite panels whose failure responses is insensitive to the existence of a central hole. This cutout insensitivity does not involve an increase in structural mass, but only the steering of the fibres in the plane of the laminate, in order to promote the redistribution of the loading towards the supported edge sections of the panel.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:4d4192c6-f576-493e-a2ad-138b4b8bbc98","http://resolver.tudelft.nl/uuid:4d4192c6-f576-493e-a2ad-138b4b8bbc98","Skeleton-based botanic tree diameter estimation from dense LiDAR data","Bucksch, A.; Lindenbergh, R.C.; Menenti, M.; Raman, M.Z.","","2009","New airborne LiDAR (Light Detection and Ranging) measurement systems, like the FLI-MAP 400 System, make it possible to obtain high density data containing far more information about single objects, like trees, than traditional airborne laser systems. Therefore, it becomes feasible to analyze geometric properties of trees on the individual object level. In this paper a new 3-step strategy is presented to calculate the stem diameter of individual natural trees at 1.3m height, the so-called breast height diameter, which is an important parameter for forest inventory and flooding simulations. Currently, breast height diameter estimates are not obtained from direct measurements, but are derived using species dependent allometric constraints. Our strategy involves three independent steps: 1. Delineation of the individual trees as represented by the LiDAR data, 2. Skeletonization of the single trees, and 3. Determination of the breast height diameter computing the distance of a suited subset of LiDAR points to the local skeleton. The use of a recently developed skeletonization algorithm based on graph-reduction is the key to the breast height measurement. A set of four relevant test cases is presented and validated against hand measurements. It is shown that the new 3-step approach automatically derives breast height diameters deviating only 10% from hand measurements in four test cases. The potential of the introduced method in practice is demonstrated on the fully automatic analysis of a LiDAR data set representing a patch of forest consisting of 49 individual trees.","Airborne Laser scanning; Skeleton; tree delineation; forestry; stem diameter","en","conference paper","Spie","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:b6565950-f68d-40c4-96f6-76ad6b6f206c","http://resolver.tudelft.nl/uuid:b6565950-f68d-40c4-96f6-76ad6b6f206c","Effect of design parameters on the flight dynamics of a Kiteplane","Terink, E.J.","","2011","","","en","conference paper","KU Leuven, OPTEC","","","","","","","","Aerospace Engineering","","","","",""
"uuid:de066274-04b9-4281-b580-3a789ad8f218","http://resolver.tudelft.nl/uuid:de066274-04b9-4281-b580-3a789ad8f218","On actuator disc force fields generating wake vorticity","Van Kuik, G.A.M.; Van Zuijlen, A.H.","","2009","Actuator disc calculations can be divided in two categories: force models where, for a prescribed force field, the flow is calculated using a CFD method, and kinematic models, where the wake is calculated based on wake boundary conditions and the force field is known when the velocities are known. In both categories, but specifically for the kinematical models, results are reported that differ some 10% from momentum models. Furthermore, most calculations which give details about the flow through the disc do not satisfy the condition derived by Xyros & Xyros (2007) that the axial velocity through the disc is uniform for discs with a uniform surface load. Apart from this, the inconsistency in the momentum models discussed by van Kuik (2003) is still unresolved. These observations raise the questions: what is the relation between force- and flow field, what are the requirements for a steady axisymmetric force field to generate vorticity in an Euler flow?","actuator disc; force field; vorticity; wake","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:505a42b5-a5ef-49f7-b6a5-b8c50e1f45d1","http://resolver.tudelft.nl/uuid:505a42b5-a5ef-49f7-b6a5-b8c50e1f45d1","Reducing uncertainties in a wind-tunnel experiment using Bayesian updating","Boon, D.J.; Dwight, R.P.; Sterenborg, J.J.H.M.; Bijl, H.","","2012","We perform a fully stochastic analysis of an experiment in aerodynamics. Given estimated uncertainties on the principle input parameters of the experiment, including uncertainties on the shape of the model, we apply uncertainty propagation methods to a suitable CFD model of the experimental setup. Thereby we predict the stochastic response of the measurements due to the experimental uncertainties. To reduce the variance of these uncertainties a Bayesian updating technique is employed in which the uncertain parameters are treated as calibration parameters, with priors taken as the original uncertainty estimates. Imprecise measurements of aerodynamic forces are used as observational data. Motivation and a concrete application come from a wind-tunnel experiment whose parameters and model geometry have substantial uncertainty. In this case the uncertainty was a consequence of a poorly constructed model in the pre-measurement phase. These methodological uncertainties lead to substantial uncertainties in the measurement of forces. Imprecise geometry measurements from multiple sources are used to create an improved stochastic model of the geometry. Calibration against lift and moment data then gives us estimates of the remaining parameters. The effectiveness of the procedure is demonstrated by prediction of drag with uncertainty.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:bb6c868b-71b8-4f69-9ae8-f31169ecf91f","http://resolver.tudelft.nl/uuid:bb6c868b-71b8-4f69-9ae8-f31169ecf91f","Evaluation of conjugate, radial heat transfer in an internally insulated composite pipe","Reurings, C.; Koussios, S.; Bergsma, O.K.; Vergote, K.","","2015","In order to compete with steel, a fibre-reinforced composite exhaust wall with a general-purpose resin system requires an effective but lightweight insulation layer. However a lack of experimental methods for heat transfer from turbulent gas flow to pipe walls lined with a porous insulation layer was discovered in literature. Such a test method is crucial to assess the influence of the permeability of such an insulation layer on the heat transfer rate, such that the lightest configuration can be selected. A new test method was developed and tested on samples representative for a composite exhaust. The accuracy of the method was assessed and the results for samples with different wall roughness were obtained. The behaviour of the samples under consideration proved to be more complicated than predicted by theories for impermeable pipe walls.","composite; heat transfer; thermal insulation; experimental; turbulent gas flow","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:ff8e44db-72e2-49fa-bd7f-bde923758e68","http://resolver.tudelft.nl/uuid:ff8e44db-72e2-49fa-bd7f-bde923758e68","An efficient method for reducing the sound speed induced errors in multibeam echosounder bathymetric measurements","Snellen, M.; Siemes, K.; Simons, D.G.","","2009","Nowadays extensive use is made of multibeam echosounders (MBES) for mapping the bathymetry of sea- and river-floors. The MBES is capable of covering large areas in limited time by emitting an acoustic pulse along a wide swathe perpendicular to the sailing direction. The angle and the corresponding two-way travel-time of the received signals are determined through beamsteering at reception. Water depths along the swathe can be derived from this angle and travel-time combination. In general, two sets of sound speed measurements are taken when conducting MBES measurements. The first set is used for the beamsteering and consists of the sound speeds at the MBES transducer. The second set is used for determining the propagation of the sound through the water column, needed for correctly converting the measured travel times to a depth. In general, this set of sound speed measurements consist of the complete sound speed profiles (SSPs). The quality of the sound speed measurements at the transducer position sometimes gets degraded, resulting in beam steering angles that differ from those aimed for. Also sometimes the SSPs used for converting the beam travel times to depths deviate from the true prevailing SSPs due to the, in general, limited amount of SSP measurements taken during a survey. Both above mentioned effects result in an erroneous bathymetry. Here, we present a method for eliminating these errors, without the need for additional sound speed information.","multibeam echosounder; sound speed profile; optimization","en","conference paper","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:d8dffa92-9780-448d-b7df-d7af0c20baa2","http://resolver.tudelft.nl/uuid:d8dffa92-9780-448d-b7df-d7af0c20baa2","Design and testing of a low subsonic wind tunnel gust generator","Lancelot, P.M.G.J.; Sodja, J.; Werter, N.P.M.; De Breuker, R.","","2015","This paper summarises the design of a gust generator and the comparison between high fidelity numerical results and experimental results. The gust generator has been designed for a low subsonic wind tunnel in order to perform gust response experiments on wings and assess load alleviation. Special attention has been given to the different design parameters that influence the shape of the gust velocity profile by means of CFD simulations. Design parameters include frequency of actuation, flow speed, maximum deflection, chord length and gust vane spacing. The numerical results are compared to experimental results obtained using a hot-wire anemometer and using flow visualisation by means of smoke. Discrepancies have been noticed between CFD and flow measurements but trends compare well and the system is fully functional.","gust generator; computational fluid dynamics; fluid structure interaction; experimental aerodynamics; experimental aeroelasticity","en","conference paper","Central Aerohydrodynamic Institute (TsAGI)","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:25d82978-fe76-4a94-a15e-3c4336147aa3","http://resolver.tudelft.nl/uuid:25d82978-fe76-4a94-a15e-3c4336147aa3","Aircraft Noise Simulation for a Virtual Reality Environment","Arntzen, M.; Van Veen, T.A.; Visser, H.G.; Simons, D.G.","","2011","Aircraft noise annoyance predictions based on traditional tools lack fidelity when modelling a single aircraft flyover. For evaluating annoyance of new procedures, different aircraft types or changing atmospheric conditions, a new modelling approach is necessary. A research effort has been initiated to develop a toolchain that links each of the relevant components. This allows the use of synthesized sound in a virtual reality simulator and enhances follow-up annoyance investigations. The toolchain components and current capabilities are presented in this paper. Audible results are illustrated by spectrograms to show the difference between different atmospheric conditions. Through the development of the toolchain, it becomes possible to demonstrate audible results of changing aircraft procedures, type and atmosphere in a virtual reality environment. This opens new ways to investigate how people value aircraft noise in different atmospheres in combination with smart planning of aircraft procedures.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:d40ce69f-57af-45b2-9514-4c40616aba88","http://resolver.tudelft.nl/uuid:d40ce69f-57af-45b2-9514-4c40616aba88","Design and Analysis of an Airborne, solid Propelled, Nanosatellite Launch Vehicle using Multidisciplinary Design Optimization","Van Kesteren, M.W.; Zandbergen, B.T.C.; Naeije, M.C.; Van Kleef, A.J.P.","","2015","The work focusses on the use of multidisciplinary optimization to design a cost optimized airborne nanosatellite launch vehicle capable of bringing a 10 kg payload into low earth orbit (LEO). Piggyback or shared launch options currently available for nanosatellites are relatively low cost (~45,000 /kg) but have as serious disadvantage a limited mission flexibility due to a limited range in attainable orbits and the launch schedule being connected to that of its fellow passengers. An alternative option, providing increased mission flexibility, is through the use of a dedicated launch vehicle, be it at a higher launch cost. An interesting option to limit the increase in launch cost is by air-launch to orbit using an already existing aircraft as carrier vehicle, i.e. first stage. This is considered beneficial especially for small launch vehicles as many potential carrier vehicles are available and because of the relatively high drag loss that is associated with ground-launch to orbit for small launch vehicles. The work presented here addresses the use of multidisciplinary optimization (MDO) methods to the design of solid rocket propelled launch vehicles, thereby taking into account both air- and ground-launch as well as the addition of lifting devices (use of wings). The method combines both vehicle and trajectory design in a sequential approach. Analysis modules included address issues concerning vehicle geometry, aerodynamics, solid rocket propulsion and vehicle mass, size and cost. The tools developed have been used to design a low-cost, solid propelled vehicle that is launched from an F-16 aircraft. Main design variables are release altitude, -velocity and -flight path angle as well as number of rocket stages, stage thrust and stage burn time. The results show an optimized, three stage launch vehicle that fits within the contours of the F-16’s 370 gallon external fuel tank and with a gross take-off mass that is up to 70% lower than that of a comparable 10-kg to LEO ground launched vehicle. The vehicle’s launch costs are estimated at 1.9 million euro per launch based on a total of 120 launches over a period of 20 years. This is a 30% reduction as compared to the cost of a comparable 10-kg to orbit optimized ground launched vehicle.","","en","conference paper","EUCASS","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:41b0ab7d-1950-48e2-b2c1-baafd15ec30e","http://resolver.tudelft.nl/uuid:41b0ab7d-1950-48e2-b2c1-baafd15ec30e","GOCE SSTI L2 tracking losses and their impact on POD performance","Van den IJssel, J.A.A.; Visser, P.N.A.M.; Doornbos, E.N.; Meyer, U.; Bock, H.; Jäggi, A.","","2011","The state-of-the-art GOCE Satellite-to-Satellite Tracking Instrument (SSTI) delivers high-quality GPS data with an almost continuous 1 Hz data rate, which allows for very Precise Orbit Determination (POD). Despite this good performance, the GPS receiver shows occasional unexpected L2 tracking losses, which mainly occur close to the geomagnetic poles and, to a lesser extent, also along the geomagnetic equator. The number of unexpected L2 tracking losses varies in time and shows some correlation with solar activity. Less than 3% of the observation data is affected by these losses. Therefore, the effect on the POD remains limited. However, systematic effects might be present, as the quality of the GOCE orbits is slightly reduced over the polar regions. The striking correlation between the global distribution of ionospheric irregularities and L2 losses suggests scintillation effects might be present. Analysis of the time derivative of the geometry-free combination of GPS phase observations shows that unexpected L2 losses occur during times of rapid ionospheric fluctuations. GPS satellites in cross-track direction are most affected by L2 losses.","GOCE; GPS; tracking losses; ionosphere; scintillations","en","conference paper","European Space Agency (ESA)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:6c1c7e9d-c6f9-455b-b811-22411680b5e7","http://resolver.tudelft.nl/uuid:6c1c7e9d-c6f9-455b-b811-22411680b5e7","Scale Development for E-Procurement (EP) Adoption Influence Tactics","Reunis, M.R.B.; Raaij, E.M.","","2006","","scale development; influence tactics; -procurement","en","conference paper","IPSERA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:99a5987a-710f-436e-8d97-9bbcd072a424","http://resolver.tudelft.nl/uuid:99a5987a-710f-436e-8d97-9bbcd072a424","Validation of the interface-GMRES(R) solution method for fluid-structure interactions","Michler, C.; Van Brummelen, E.H.; In 't Groen, R.; De Borst, R.","","2006","The numerical solution of fluid-structure interactions with the customary subiteration method incurs numerous deficiencies. We validate a recently proposed solution method based on the conjugation of subiteration with a Newton-Krylov method, and demonstrate its superiority and beneficial characteristics.","fluid-structure interaction; subiteration; Newton-Krylov method; GMRES; reuse of Krylov vectors","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e4b27583-6749-4c44-8624-b7b234779451","http://resolver.tudelft.nl/uuid:e4b27583-6749-4c44-8624-b7b234779451","A Runge-Kutta Discontinuous-Galerkin Level-Set Method for Unsteady Compressible Two-Fluid Flow","Naber, J.; Koren, B.","","2006","In this work a numerical method for the solution of the two-dimensional Euler equations describing unsteady compressible two-fluid flow is presented. The method is based on the combination of a Runge-Kutta discontinuous Galerkin discretization of the Euler equations and a level-set method for the treatment of the two-fluid interface. The corresponding level-set equation is used in its advective form which, as opposed to the frequently used conservative form, does not generate an erroneous off-set in the interface location. A simple fix is applied to prevent the solution from becoming oscillatory near the two-fluid interface. Application of this fix requires the development of a special two-fluid slope limiter for the discontinuous Galerkin method. Numerical results show the competence of the developed method.","two-fluid flow; level-set method; discontinuous-Galerkin; slope limiters","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6ceaaba0-a989-4888-ae11-35791f10a8ab","http://resolver.tudelft.nl/uuid:6ceaaba0-a989-4888-ae11-35791f10a8ab","J1026+2542: Proper motion in a blazar jet at z=5.27","Frey, S.; Paragi, Z.; Fogasy, J.O.; Gurvits, L.","","2014","The radio-loud AGN J1026+2542 has recently been classified as the second most distant blazar, based on its broad-band spectral energy distribution and X-ray spectrum. The source with a prominent one-sided jet extending to at least ?20 mas was earlier observed with the VLBA at 5 GHz in January 2006. With our new EVN observation (May 2013), we detected the displacement and directly measured the apparent proper motion of the jet components, for the first time at such a high redshift. The 1.6-GHz EVN observation provided additional information on the extent and the spectral properties of the jet. The VLBI results are consistent with the picture in which J1026+2542 has its jet oriented close to the line of sight, with significant Doppler boosting and a large bulk Lorentz factor.","","en","conference paper","POS","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:0edbe7a4-3b36-48c6-b3d4-72b412063d88","http://resolver.tudelft.nl/uuid:0edbe7a4-3b36-48c6-b3d4-72b412063d88","Integrating systems and business engineering in an international context: The SpaceTech Postgraduate Program","Gill, E.K.A.; Kreisl, J.; Verma, D.","","2009","Successful education of engineers needs continuous adaptation to track the changing needs of industry. The adaptation is not limited to technological advance or to the changing mentality of new students but also to end-to-end engineering approaches using Systems Engineering. However, industries today require more and more engineers with profound knowledge of business engineering to arrive at successful products – a fact which universities typically have not sufficiently taken into account yet. The SpaceTech program of the Delft University of Technology is an international postgraduate program for experienced high potentials seeking expertise in space systems and business engineering. The program centres around a Central Case Project where a group of international participants exercise space systems engineering fundamentals together with marketing and business engineering tools to create a financially viable virtual business. Based on more than 10 years of experience from the SpaceTech program, the learning objectives of Systems Engineering and business engineering and their interrelations are analyzed. Topics of past Central Case Projects are summarized and trends are extracted. The potentials of integrating Systems and Business Engineering are identified and their limitations in an educational environment are addressed.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:83dd41be-78c7-41c9-88de-d6422d968317","http://resolver.tudelft.nl/uuid:83dd41be-78c7-41c9-88de-d6422d968317","A 3d unsteady panel method for vertical axis wind turbines","Dixon, K.; Simao Ferreira, C.J.; Hofemann, C.; Van Bussel, G.J.W.; Van Kuik, G.A.M.","","2008","","VAWT; panel method; near wake structure","en","conference paper","European Wind Energy Association EWEA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:81f56390-d22a-444d-b2b1-88c6f7515b79","http://resolver.tudelft.nl/uuid:81f56390-d22a-444d-b2b1-88c6f7515b79","Flow Separation Control on Airfoil With Pulsed Nanosecond Discharge Actuator","Correale, G.; Popov, I.B.; Ratikin, A.E.; Starikovskii, A.Y.; Hulshoff, S.J.; Veldhuis, L.L.M.","","2011","An experimental study of flow separation control with a nanosecond pulse plasma actuator was performed in wind-tunnel experiments. The discharge used had a pulse width of 12 ns and rising time of 3 ns with voltage up to 12 kV. Repetition frequency was adjustable up to 10 kHz. The first series of experiments was to measure integral effects of the actuator on lift and drag. Three different airfoil models were used, NACA-0015 with the chord of 20 cm, NLF-MOD22A with the chord of 60 cm and NACA 63-618 with the chord of 20 cm. Different geometries of the actuator were tested at flow speeds up to 80 m/s. In stall conditions the significant lift increase up to 20% accompanied by drag reduction (up to 3 times) was observed. The critical angle of attack shifted up to 5–7 degrees. The relation of the optimal discharge frequency to the chord length and flow velocity was proven. The dependence of the effect on the position of the actuator on the wing was studied, showing that the most effective position of the actuator is on the leading edge in case of leading edge separation. In order to study the mechanism of the nanosecond plasma actuation experiments using schlieren imaging were carried out. It shown the shock wave propagation and formation of large-scale vortex structure in the separation zone, which led to separation elimination. PIV diagnostics technique was used to investigate velocity field and quantitative properties of vortex formation. In flat-plate still air experiments small scale actuator effects were investigated. Measured speed of flow generated by actuator was found to be of order of 0.1 m/s and a span-wise nonuniformity was observed. The experimental work is supported by numerical simulations of the phenomena. The formation of vortex similar to that observed in experiments was simulated in the case of laminar leading edge separation. Model simulations of free shear layer shown intensification of shear layer instabilities due to shock wave to shear layer interaction.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:228fe067-3798-485e-858d-6178b18bd9d6","http://resolver.tudelft.nl/uuid:228fe067-3798-485e-858d-6178b18bd9d6","Optimized three-unit cubesat structure for Delfi-n3Xt","Go, S.Y.; Bouwmeester, J.; Brouwer, G.F.","","2008","For the Delfi-n3Xt mission, follow-up to CubeSat Delfi-C3 [1] of Delft University of Technology, several concepts concerning the Structural Subsystem (STS) have been analysed. One of the main objectives is to reduce the time needed for assembly, integration and testing, and to improve handling capabilities. Lessons learned from Delfi-C3 have been taken into account in a trade-off between several candidate design options. A brief description of the structure of Delfi-C3 is given. Afterwards the candidate options for the STS of Delfi-n3Xt are discussed, followed by the final structure selection and implementation.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:75dc2165-950b-4a42-b1a1-5e2bc2dfd209","http://resolver.tudelft.nl/uuid:75dc2165-950b-4a42-b1a1-5e2bc2dfd209","Aerodynamic analysis of the wing flexibility and the clap-and-peel motion of the hovering DelFly II","Gillebaart, T.; Van Zuijlen, A.H.; Bijl, H.","","2011","In this paper, the influence of wing flexibility and the 'clap-and-peel' motion (one versus two wings) on the upward (lifting) force in hover is studied. CFD simulations based on the ALE Navier-Stokes equations together with radial basis function mesh interpolation are used. For the 'clap-and-peel' motion an immersed symmetry plane is introduced into the computational domain. The flexible shapes of the wing are obtained from experiments. From the preliminary results it can be concluded that flexibility enhances the production of the upward force.","Micro Air Vehicle; flapping wing; aerodynamics","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:b46be62c-9272-4708-92ff-46f8d6135119","http://resolver.tudelft.nl/uuid:b46be62c-9272-4708-92ff-46f8d6135119","The Use of the Dynamic Solution Space to Assess Air Traffic Controller Workload","D'Engelbronner, J.G.; Mulder, M.; Van Paassen, M.M.; De Stigter, S.; Huisman, H.","","2010","Air traffic capacity is mainly bound by air traffic controller workload. In order to effectively find solutions for this problem, off-line pre-experimental workload assessment methods are desirable. In order to better understand the workload associated with air traffic control, previous research introduced the static Solution Space as a possible workload metric. The Solution Space Diagram is a mapping of intruding aircraft trajectories to the velocity/heading plane in the form of Conflict Zones and safe areas. Choosing a velocity vector in either one will provide an unsafe or a safe solution, respectively. In this paper an improved, dynamic Solution Space will be tested for correlations with air traffic controller workload, measured experimentally. A two dimensional experiment has been conducted, where subjects were required to line up all aircraft in a sector towards a certain waypoint, while continuously providing subjective workload ratings. High correlations were found between several Solution Space parameters and the subjective workload. Even though a conventional workload metric shows also to be highly correlated to the measured workload, the Solution Space could be the scenario independent workload metric that is currently missing in air traffic controller workload determination.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:0c9ec36a-94fd-4de7-adfc-716762604df9","http://resolver.tudelft.nl/uuid:0c9ec36a-94fd-4de7-adfc-716762604df9","Identifying corresponding segments from repeated scan data","Van Goor, B.; Lindenbergh, R.C.; Soudarissanane, S.S.","","2011","It has been demonstrated that surface changes in the order of millimeters are detectable using terrestrial laser scanning. In practice however, it is still virtually impossible to detect such small changes from for example repeated scans of a complex industrial scene. The three main obstructions are, first, a priori uncertainty on what objects are actually changing, second, errors introduced by registration, and third, difficulties in the identification of identical object parts. In this paper we introduce a method enabling efficient identification that can also be applied to evaluate the quality of a registration. The method starts with a pair of co-registered point clouds, at least partially representing the same scene. First, both point clouds are segmented, according to a suited homogeneity criterion. Based on basically orientation and location, corresponding segment parts are identified, while lack of correspondence leads to the identification of either occlusions or large changes. For the corresponding segments, subtle changes at the millimeter level could be analyzed in a next step. An initial version of the new method is demonstrated on repeated scan data of a metro station experiencing heavy construction works.","change detection; LIDAR; point cloud; segmentation; identification","en","conference paper","International Society for Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:0b81ba7f-4bec-47a0-97a9-82f13f09f606","http://resolver.tudelft.nl/uuid:0b81ba7f-4bec-47a0-97a9-82f13f09f606","A Monotone, Higher-Order Accurate, Fixed-Grid Finite-Volume Method for Advection Problems with Moving Boundaries","Hassen, Y.J.; Koren, B.","","2008","","","en","conference paper","University of Liege","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e6b55e06-6776-4348-ae99-1e5bc9181d61","http://resolver.tudelft.nl/uuid:e6b55e06-6776-4348-ae99-1e5bc9181d61","On in-situ visualization for strongly coupled partitioned fluid-structure interaction","Fernandes, O.; Blom, D.S.; Frey, S.; Van Zuijlen, A.H.; Bijl, H.; Ertl, T.","","2015","We present an integrated in-situ visualization approach for partitioned multi-physics simulation of fluid-structure interaction. The simulation itself is treated as a black box and only the information at the fluid-structure interface is considered, and communicated between the fluid and solid solvers with a separate coupling tool. The visualization of the interface data is performed in conjunction with the fluid solver. Furthermore, we present new visualization techniques for the analysis of the interrelation of the two solvers , with emphasis on the involved error due to discretization in space and time and the reconstruction. Our visualization approach also enables the investigation of these errors with respect of their mutual influence on the two simulation codes and their space-time discretization. For efficient interactive visualization, we employ the concept of explorable spatiotemporal images, which also enables finite-time temporal navigation in an in-situ context. We demonstrate our overall approach and its utility by means of a fluid-structure simulation using OpenFOAM that is coupled by the preCICE software layer.","in-situ visualization; fluid-structure interaction; multi-physics","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:9ec044b0-1ef8-4763-befa-d44a8c6a8650","http://resolver.tudelft.nl/uuid:9ec044b0-1ef8-4763-befa-d44a8c6a8650","Correcting bathymetry measurements for water sound speed effects using inversion theory","De Plaa, J.; Snellen, M.; Simons, D.G.","","2008","","","en","conference paper","Société Française d'Acoustique","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:7e3a3d6d-f141-41a3-b6db-369896928c2e","http://resolver.tudelft.nl/uuid:7e3a3d6d-f141-41a3-b6db-369896928c2e","Efficient design and manufacturing of the seats of the Superbus","Terzi, A.; Ozcelik, D.; Ockels, W.J.","","2008","The Superbus is a new public transport vehicle designed for fast, safe, comfortable, sustainable and flexible transportation. The vehicle travels at 250 km/h on its dedicated infrastructures and at conventional speed on existing roads, and transports passengers and goods from point to point, without the need to change transport during the journey. Due to the challenging vehicle operational requirements, the seat design had to be optimized with regard to comfort, weight constrains, accessibility, attachments to the chassis, 3-point seatbelt attachments, manufacturability aspects and cost. For that, the seat features a new design and its structure is made of carbon fiber. In this paper the analysis of the interior design will be discussed in correlation to the operational requirements. Then, the resulting overall interior layout of the vehicle will be described (Figure 1). Finally, the seat design, the relative material used and manufacturing processes will be described within the context of the interior design and manufacturing.","","en","conference paper","Society for the Advancement of Material and Process Engineering","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:40941cf4-0bd3-4534-b9c0-a16259f9e6f6","http://resolver.tudelft.nl/uuid:40941cf4-0bd3-4534-b9c0-a16259f9e6f6","Model based tuning of the release of self healing agents from organic coatings: From Fickian to controlled release kinetics (abstract)","Javierre, E.; Garcia Espallargas, S.J.; Mol, J.M.C.; Vermolen, F.J.; Vuik, C.; Van der Zwaag, S.","","2011","","self-healing; pigment release; corrosion inhibition; Fickian; non-Fickian; modelling","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:2ac4cd53-cbc5-492f-895b-5f8fca76e1df","http://resolver.tudelft.nl/uuid:2ac4cd53-cbc5-492f-895b-5f8fca76e1df","Advanced noise abatement departure procedures: Custom optimized departure profiles","Hebly, S.J.; Visser, H.G.","","2008","","","en","conference paper","American Institute of Aeronautics and Astronautics AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1ca8ff35-d84a-45bd-9567-c93f39318896","http://resolver.tudelft.nl/uuid:1ca8ff35-d84a-45bd-9567-c93f39318896","Higher order implicit time integration schemes to solve incompressible Navier-Stokes on co-located grids using consistent unsteady Rhie-Chow","Kazemi Kamyab, V.; Van Zuijlen, A.H.; Bijl, H.","","2012","Noting that time-accurate computations of the unsteady incompressible Navier-Stokes (INS) equations can be computationally expensive, a family of higher order implicit multi-stage time integration schemes (namely ESDIRK) is used for advancing the solution to the unsteady INS in time. The higher order time integration schemes have the potential to decrease the computational cost of obtaining engineering levels of accuracy relative to the traditionally used 2nd order implicit schemes. The finite volume method is used for spatial discretization, and co-located arrangement of the primitive variables is considered. Furthermore, an iterated PISO algorithm is used to solve the incompressible Navier-Stokes equations. By using a temporally consistent Rhie-Chow interpolation, higher order temporal accuracy in solving the INS equations on co-located grids is achieved. For a two-dimensional lid driven cavity test case, the temporal convergence of the solution is investigated, with the third and fourth order ESDIRK schemes for time integration. The results demonstrate the temporal consistency and temporal order preservation of the algorithm.","incompressible Navier-Stokes; Rhie-Chow interpolation; implicit time integration; OpenFoam","en","conference paper","Vienna University of Technology","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:05f630e7-4926-4df6-a50a-71126c44596c","http://resolver.tudelft.nl/uuid:05f630e7-4926-4df6-a50a-71126c44596c","Spacecraft VLBI and Doppler tracking: Algorithms and implementation","Duev, D.A.; Molera Calvés, G.; Pogrebenko, S.V.; Gurvits, L.I.; Cimó, G.; Bocanegra Bahamon, T.","","2012","Aims. We present the results of several multi-station Very Long Baseline Interferometry (VLBI) experiments conducted with the ESA spacecraft Venus Express as a target. To determine the true capabilities of VLBI tracking for future planetary missions in the solar system, it is necessary to demonstrate the accuracy of the method for existing operational spacecraft. Methods. We describe the software pipeline for the processing of phase referencing near-field VLBI observations and present results of the ESA Venus Express spacecraft observing campaign conducted in 2010?2011. Results. We show that a highly accurate determination of spacecraft state-vectors is achievable with our method. The consistency of the positions indicates that an internal rms accuracy of 0.1 mas has been achieved. However, systematic effects produce offsets up to 1 mas, but can be reduced by better modelling of the troposphere and ionosphere and closer target-calibrator configurations.","instrumentation: interferometers instrumentation: miscellaneous techniques: interferometric astrometry","en","conference paper","EDP Sciences","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:f367da87-2804-4a8b-b192-eb053eca8126","http://resolver.tudelft.nl/uuid:f367da87-2804-4a8b-b192-eb053eca8126","An extensive and autonomous deep space navigation system using radio pulsars","Kestilä, A.A.; Engelen, S.; Gill, E.K.A.; Verhoeven, C.J.M.; Bentum, M.J.; Irahhauten, Z.","","2010","Interstellar navigation poses significant challenges in all aspects of a spacecraft. One of them is reliable, low-cost, real-time navigation, especially when there is a considerable distance between Earth and the spacecraft in question. In this paper, a complete system for navigation using pulsar radio emissions is described and analysed. The system uses a pulsar?s emissions in the radio spectrum to create a novel system capable of fully autonomous navigation. The system is roughly divided into two parts, the front - end and the back - end, as well as their subdivisions. The front - end performs initial signal reception and pre-processing. It applies time-based coherent de-dispersion to allow for low-power on-board processing, and uses a very wide bandwidth to limit the required antenna size. As a result, the electronics required performing the processing is complex, but the system is well limited in both size and power consumption. The back-end, in turn, performs advanced nonlinear Kalman filtering and supplies the final navigational product - the systems complete (position and velocity) state vector, as well as the involved uncertainties. Rather uniquely, it uses two inherent signal properties, the Doppler shift and the inherent pulse period slowdown, simultaneously, to obtain both a relative and an absolute estimate of the spacecraft's position. Combined, in the nonlinear Kalman filter, they result in the complete state vector of the system. Performance of the system was analysed and validated using actual telescope data from the LOFAR array. The results show that the front-end can indeed receive and process even a very weak signal from an actual pulsar, while the back-end can output a navigational product despite significant random noise in the signal data received from the front-end.","","en","conference paper","International Astronautical Federation","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:a537388f-c526-45ee-b762-514a8d0ed14f","http://resolver.tudelft.nl/uuid:a537388f-c526-45ee-b762-514a8d0ed14f","The flyby anomaly: An investigation into potential causes","Jouannic, B.; Noomen, R.; Van den IJssel, J.A.A.","","2015","Since December 1990, a number of spacecraft have performed a flyby around Earth in which an unexpected change in velocity has been observed, which has not been explained so far: the so-called flyby anomaly. The effect on the excess velocity has been expressed in an empirical relation by Anderson, which was based on data on 6 such flybys. However, new flybys did not fit this expression anymore. This paper has made a statistical analysis on a total of 12 flybys (not all of them showing such an anomaly), which has resulted in an improved empirical relation. In addition, the study has investigated a number of physical candidate explanations. Atmospheric drag was rejected as a potential cause, whereas direct solar radiation pressure is a possible candidate, either expressed as an overall coefficient CR or effectuated by (small) changes in reflectivity coefficients. However, because of lack of data (tracking data, attitude information) no firm conclusions can be drawn.","flyby; anomaly; astrodynamics; solar radiation pressure","en","conference paper","DLR","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:2f0cb555-07c4-47ad-9c30-c61c14a00beb","http://resolver.tudelft.nl/uuid:2f0cb555-07c4-47ad-9c30-c61c14a00beb","A Monomial Chaos Approach for Efficient Uncertainty Quantification in Computational Fluid Dynamics","Witteveen, J.A.S.; Bijl, H.","","2006","A monomial chaos approach is proposed for efficient uncertainty quantification in nonlinear computational problems. Propagating uncertainty through nonlinear equations can still be computationally intensive for existing uncertainty quantification methods. It usually results in a set of nonlinear equations which can be coupled. The proposed monomial chaos approach employs a polynomial chaos expansion with monomials as basis functions. The expansion coefficients are solved for using implicit differentiation of the governing equations. This results in a decoupled set of linear equations even for nonlinear problems, which reduces the computational work per additional polynomial chaos order to the equivalence of one Newton iteration. The results of the monomial chaos applied to nonlinear advection-diffusion are compared with results of the perturbation method, the Galerkin polynomial chaos method and a non-intrusive polynomial chaos method with respect to a Monte Carlo reference solution. The accuracy of the monomial chaos can be further improved by estimating additional coefficients using extrapolation.","uncertainty quantification; computational fluid dynamics; polynomial chaos","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:467617ff-fc83-4f1e-92a5-04728ff916f2","http://resolver.tudelft.nl/uuid:467617ff-fc83-4f1e-92a5-04728ff916f2","Delft Aerospace engineering integrated curriculum","Kamp, A.","","2011","The complex multidisciplinary problems and challenges in our society require deep problem solvers in science, management and engineering who are also capable of interacting with and understanding specialists from a wide range of disciplines and functional areas. Industry refers to these people as T-shaped professionals. The T-shaped professional model has been the reference for the bachelor and master curricula in Aerospace Engineering at Delft University of Technology. The bachelor provides the broad academic background in the domain of aerospace engineering. The life cycle of the engineering process and contextual storylines of famous persons in aviation, aeronautics or space form the cement and thread for the themes of the bachelor curriculum. The bachelor develops the academic intellectual skills and attitudes to analyse, apply, synthesize, and design, and prepares for the master. The master programme aims to develop the basic competences acquired in the bachelor to a higher level in terms of knowledge, critical reflection, making judgements and working independently. While “engineering and design” is the central theme of the bachelor, “research” is the theme of the master. This curricular framework gives the bachelor and master an own profile and identity. They use state-of-the-art content that is interwoven with thematic design projects and trainings for personal and system building skills, using international standard text books, up-to-date teaching methods, excellent facilities, with a focus on the aircraft and spacecraft throughout the programmes. Excellence programmes are available for the top 5 percent students in both bachelor and master. In these honours classes self-regulated students define their personal learning objectives and levels to be attained. Their key concept is that of open-ended learning and autonomy. In the bachelor the excellence programme substitutes design projects in the regular curriculum by one ambitious and compelling project with a high societal relevance and visibility. In the master it is a halfyear add-on programme about taking the lead in the creation and operation of new products, systems or processes, and developing awareness and understanding of the importance and strategic impact of research and technological developments on society.","integrated curriculum; T-shaped professional; aerospace; engineering education","en","conference paper","CDIO","","","","","","","","Aerospace Engineering","Support Aerospace Engineering","","","",""
"uuid:57e2bef2-18bc-4014-8e34-c10d66c6a40a","http://resolver.tudelft.nl/uuid:57e2bef2-18bc-4014-8e34-c10d66c6a40a","An Application of the IPROD Software Framework to Support the Product Development Process in the Automotive and Aerospace Domain","Hoogreef, M.F.M.; Van Dijk, R.E.C.; La Rocca, G.; d'Ippolito, R.","","2014","The Product Development Process (PDP) of manufacturing companies requires the efficient management of huge amounts of data from different sources and their integration in the sub-processes that compose the product development chain. This is a very challenging endeavor for which an integrated approach does not yet exist. The EC FP7 Project iProd aims at filling this void, by developing a flexible and service-oriented software framework, supported by a knowledge base that is structured by means of ontologies, to improve the efficiency and the quality of the PDP in the preliminary design phase. This paper discusses the first prototype of this software framework. The logic, overall software architecture and some of the implementations details of the framework are described. The functionalities of the software framework are demonstrated by means of two use-cases from two different domains, i.e. the automotive domain, represented by the development process of a car door, and the aerospace domain, represented by the development process of a rudder for a business jet. Preliminary testing, using the first prototype, indicates that the application of the framework to the two use-cases can yield benefits in terms of a reduction in development time in the preliminary design phase and results in product quality improvements, by having additional time for more design iterations to increase the maturity level during this phase. However, the framework is to be improved in terms of reliability, efficiency and maintainability. These improvements will be done during the development of two more software prototypes.","capturing product information; knowledge engineering; knowledge management; industrial workflow enhancement; ontologies; knowledge-based technologies to support the product development process","en","conference paper","TMCE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:8a2afffb-7b8d-4d17-b2a2-47bfcf03816f","http://resolver.tudelft.nl/uuid:8a2afffb-7b8d-4d17-b2a2-47bfcf03816f","A Value Operations Methodology for Value Driven Design: Medium Range Passenger Airliner Validation","Curran, R.; Abu-Kias, T.; Repco, M.J.F.; Sprengers, Y.L.J.; Van der Zwet, P.N.C.S.; Beelearts, W.","","2010","This paper gives insight in the development of a Value Operations Methodology (VOM) that can be used to support Value Driven Design (VDD). The VOM establishes expressions for operational value levers that are incorporated into a weighted value function. This value function is then used to optimize the design variables that are incorporated into it so that the design process is actively driven by value assessments that provide design decision metrics. However, the VOM is generic in nature and has a much wider range of influence to the design process for any engineering product. The methodology is verified by means of a case study, analyzing the value difference between the Boeing 737-200, Boeing 737-800, Embraer ERJ-145 and the Airbus 319 as part of a use-case study. In fact, the fundamental conclusion from the work presented is actually that VDD simply promotes the sustained application of the main utility values that were originally recognised but which, due to the complexity of the product and enterprise, tends to be disaggregated into isolated requirements. Ultimately, this leads to optimisation at a sub-system level and that is especially unacceptable for a complex system (with many sub-systems), whereas the re-focus of VOM helps to significantly shift the design effort back to creatively solving the main goal, rather than simply and somewhat robotically making sure the requirements are satisfied. The verification and validation work presented is recognised as indicative but the authors believe that it is extremely significant in pointing towards the potential gains from sustaining a more holistic appraisal and approach through-out the design process. Notwithstanding, the key message of the paper is the need for value modelling within engineering so that we are in control of the consequences of what we are actualising, where value is realised through operational delivery and excellence! This paper has presented a broad methodology in opening up a significantly different approach to aircraft design that may well still be economically driven but incorporating drivers of a much more holistic cause: proactively rather than reactively!","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:3f158a63-41c0-4fdc-9337-6d155a44b4ca","http://resolver.tudelft.nl/uuid:3f158a63-41c0-4fdc-9337-6d155a44b4ca","Interface control procedures for university satellite programmes","Perez Lebbink, L.; Hamann, R.J.; Bouwmeester, J.; Brouwer, G.F.","","2009","Now that more and more universities have joined the CubeSat community and have their own satellite in Earth orbit, it is expected that the planned successors will be of higher complexity. These successors within a university satellite programme will often house more technically ad-vanced subsystems as well as more challenging technology demonstrations for external partners. Also, the number of these third-party experiments is expected to increase throughout the programme. In order to have successful projects, these developments ask for a robust and well-defined inter-face control approach. Interface control ensures the proper mutual development of satellite systems and coordination of simultaneously operating design teams. Well-defined and properly implemented interface control procedures prevent engineers from designing non-complying components that are unable to be correctly incorporated into the satellite. Redesigns are thereby less likely. The characteristics of university satellite projects ask for a different approach to systems engi-neering techniques than what is common within industry. This is attributable to a scarcity of resources, most notably manpower and budget. Considering these limitations, above all, inter-face control procedures have to be practically implementable. This paper proposes a set of interface control tools and procedures which are based on common industry practice, but scaled down for university satellite programmes. By elaborating on the proposed tools for interface control one should be able to set up an own set of tools, customized to its own project. Imple-mentation of the interface control tools and procedures is illustrated based on the Delfi-n3Xt satellite development of the Delft University of Technology where the procedures are currently in place.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:98c4e7ec-5fe7-42ce-a5f2-346a4b8d51d8","http://resolver.tudelft.nl/uuid:98c4e7ec-5fe7-42ce-a5f2-346a4b8d51d8","Actuator Fault Detection and Diagnosis for Quadrotors","Lu, P.; Van Kampen, E.J.; Yu, B.","","2014","This paper presents a method for fault detection and diagnosis of actuator loss of effectiveness for a quadrotor helicopter. This paper not only considers the detection of the actuator loss of effectiveness faults, but also addresses the diagnosis of the faults. The detection and estimation of the faults are performed by the Augmented Extended Kalman Filter. The faults are modelled as random walk processes and are treated as additional states which makes the fault estimation unbiased. The estimated faults can be further used for Fault Tolerant Control. Simulation both without and with the occurrence of the actuator faults demonstrates the effectiveness of the proposed approach.","Micro Air Vehicle; fault detection","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:b238d3b9-6d12-4b49-8bd7-8b493073512f","http://resolver.tudelft.nl/uuid:b238d3b9-6d12-4b49-8bd7-8b493073512f","The Application of the Probabilistic Collocation Method to a Transonic Axial Flow Compressor","Loeven, G.J.A.; Bijl, H.","","2010","In this paper the Probabilistic Collocation method is used for uncertainty quantification of operational uncertainties in a transonic axial flow compressor (i.e. NASA Rotor 37). Compressor rotors are components of a gas turbine that are highly sensitive to operational and geometrical uncertainties. Validation of the Probabilistic Collocation method with a Monte Carlo simulation using 10,000 Latin Hypercube samples demonstrated that the Probabilistic Collocation method can successfully be applied to a turbomachinery case. The flow through the rotor is characterized by a bow shock in front of the leading edge, which interacts with the boundary layer of the next blade. The total pressure profile at the inlet of the rotor is assumed to be uncertain. A symmetric beta distribution was used for the pressure profile, with the standard deviation such that the uncertainty is in the same order of the measurement accuracy reported in literature. The mass flow was shown to be the most sensitive to the uncertainty, while the efficiency is least affected. It was shown by the compressor maps that is important to take the uncertainty in the total pressure profile at the inlet into account. The standard deviation of the static pressure field showed that the largest variation is present near the shock wave and mainly in the region of the strongest shock, which is near the tip of the blade.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:82d7d90c-a3bc-4e1b-b999-41b3c80ccd19","http://resolver.tudelft.nl/uuid:82d7d90c-a3bc-4e1b-b999-41b3c80ccd19","High-frequency multibeam echosounder classification for rapid environmental assessment","Siemes, K.; Snellen, M.; Simons, D.G.; Hermand, J.P.; Meyer, M.; Le Gac, J.C.","","2008","","","en","conference paper","Société Française d'Acoustique","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:2d30c0c3-603d-45aa-aa1e-e47eeb936187","http://resolver.tudelft.nl/uuid:2d30c0c3-603d-45aa-aa1e-e47eeb936187","Instantaneous planar pressure field determination based on time-resolved Stereo-PIV","De Kat, R.; Van Oudheusden, B.W.; Scarano, F.","","2008","","","en","conference paper","TUD/EWA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:aa863e14-6627-4b86-be68-84cb1dfbefd8","http://resolver.tudelft.nl/uuid:aa863e14-6627-4b86-be68-84cb1dfbefd8","Achieving Individual Adoption of an e-ordering applications with a 'benefit imbalance'","Reunis, M.R.B.; Santema, S.C.","","2005","","influence tactics; adoption; Compliance; e-ordering","en","conference paper","Amsterdam, Vrije Universiteit","","","","","","","","Aerospace Engineering","","","","",""
"uuid:864483bc-78dd-48d9-9dc1-12af8ae0b347","http://resolver.tudelft.nl/uuid:864483bc-78dd-48d9-9dc1-12af8ae0b347","Offshore wind turbine design using site data","Sathe, A.R.","","2007","","","en","conference paper","European Academy for Wind Energy EAWE","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b7d1c441-d923-4fb6-be31-974f5c7ab46e","http://resolver.tudelft.nl/uuid:b7d1c441-d923-4fb6-be31-974f5c7ab46e","A Maximum Information Rate Quaternion Filter for Spacecraft Attitude Estimation","Reijneveld, J.; Maas, A.; Choukroun, D.; Kuiper, J.M.","","2011","Building on previous works, this paper introduces a novel continuous-time stochastic optimal linear quaternion estimator under the assumptions of rate gyro measurements and of vector observations of the attitude. A quaternion observation model, which observation matrix is rank degenerate, is reduced to a two-dimensional model via a maximum information rate approach. The resulted filter combines the exact treatment of the quaternion process state-dependent noise and the quaternion measurement state-dependent noise under the framework of continuous-time optimal linear filtering. This yields statistically consistent covariance computations within the proposed filter without requiring tuning. The case of white noises in the gyro and vector measurements are considered in this work. This paper also presents the development of a Sun vector determination subsystem for the nanosatelite Delfi-N3xt. Simulations and preliminary experimental validation show that this subsystem, which consists of six four-quadrant Sun sensors, can deliver a Sun-spacecraft line of sight with an averaged equivalent angular error of approximately 0.2 deg without the Earth albedo. The performances of the novel filter are illustrated via extensive Monte-Carlo simulations in the case of Delfi-N3xt, where Sun vector measurements, Earth magnetic measurements and gyro measurements are acquired along a 600 km height Sun synchronous orbit. The proposed filter appears to be insensitive to poor initial conditions and low sampling rates. It converges where a standard extended Kalman filter fails to do so under the same conditions.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:bc7f0f94-4a13-4417-893d-c8c6e36f2bbc","http://resolver.tudelft.nl/uuid:bc7f0f94-4a13-4417-893d-c8c6e36f2bbc","Unravelling the corrosion protection mechanism of silyl ester by combined electrochemistry and x-ray computed tomography","Garcia Espallargas, S.J.; Wu, X.","","2013","Recently, encapsulated silyl esters have been shown to act as efficient healing agents for self-healing anticorrosive coatings. While the positive protective effects were irrefutable, the actual protection mechanism has not been clarified yet. In this study, x-ray computed ?-tomography and electrochemical impedance spectroscopy have been employed to unravel the protection mechanisms for a coated AA7050 aluminium alloy. The results show that the employed silyl ester protects the damaged coating-metal system by delaying the delamination initiation and growth kinetics while at the same time decreasing the underfilm pit area growth. The study also shows the potential of x-ray computed ?-tomography to follow the delamination front line and underfilm pits in coated metallic samples. The combination with EIS led to a major understanding of both EIS plots and the protection mechanisms offered by the silyl ester used.","silyl ester; delamination; coating; x-ray tomography; impedance","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:03ed744e-d656-4f7c-b2bc-7bc8567f35de","http://resolver.tudelft.nl/uuid:03ed744e-d656-4f7c-b2bc-7bc8567f35de","InSAR based validation of MERIS IWV cloud gap filling using GPS IWV","Lindenbergh, R.C.; Liu, S.; Hanssen, R.; De Haan, S.; Van der Marel, H.","","2009","High spatial resolution integrated water vapor (IWV) estimates are available from the MERIS spectrometer on board of Envisat. Unfortunately cloud cover results in loss of a large amount of MERIS IWV pixels. Here methods are presented for filling cloud gaps in MERIS IWV scenes, first, by directly interpolating remaining pixels not affected by clouds, and second, by fusion with cloud insensitive IWV observations from ground stations of the GPS network. Results are validated by independent IWV estimates obtained from suited SAR interferograms. The results indicate that the procedure works mathematically in a correct way, but that the physical application of the results is strongly hampered by MERIS pixels affected by not automatically detected clouds.","","en","conference paper","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:b5e883ee-54a7-4dea-bd60-db190d0bafdd","http://resolver.tudelft.nl/uuid:b5e883ee-54a7-4dea-bd60-db190d0bafdd","Modelling of a Hybrid UAV Using Test Flight Data","Smeur, E.J.J.; Chu, Q.P.; De Croon, G.C.H.E.; Remes, B.; De Wagter, C.; Van der Horst, E","","2014","The concept of an aircraft capable of both hover as well as fast forward flight (hybrid) has recently been implemented on unmanned aerial vehicles (UAV). Hybrid UAVs combine hover capability with long range and endurance. As UAVs are often required to operate without human intervention, there is a call for autonomous guidance of hybrid UAVs. Because the dynamics in the transition region from hover to forward flight are not well known, this research focusses on the development of a longitudinal model for a hybrid UAV based on test flight data. The same approach can be used for other types of airframes as well, allowing cheap and easy modelling. Sensors were logged for nine different flights and a Kalman filter was used for state estimation. The system was excited by doublet inputs on the commanded pitch and thrust. From the input-output response a piecewise linear model was estimated. This model was verified by comparing the measured doublet input response to the simulated response based on the model, yielding a very similar result.","IMAV2014; MAV; Micro Air Vehicle; hybrid UAV; test flight data","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:14430c56-26d9-438d-89aa-55fd2648e2fc","http://resolver.tudelft.nl/uuid:14430c56-26d9-438d-89aa-55fd2648e2fc","Capturing the journey of wind from the wind turbines (poster)","Giyanani, A.H.; Bierbooms, W.A.A.M.; Van Bussel, G.J.W.","","2015","Wind turbine design, control strategies often assume Taylor’s frozen turbulence where the fluctuating part of the wind is assumed to be constant. In practise, the wind turbine faces higher turbulence in case of gusts and lower turbulence in some cases. With Lidar technology, the frozen turbulence assumption could be avoided and the evolution of wind towards the wind turbine could be studied. This studey therefore bridges the gap between measurements and controls of the turbine. In this poster, the autoregressive methods for prediction of the wind speeds evolving from farwind to nearwind are analysed and an empirical state space model is developed. The results are therefore useful in developing the transfer function for efficient wind turbine control thereby, reducing fatigue and extreme loads in the wind turbine.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:66cbbcaa-4e08-4ed0-8fc9-6782c6e28a14","http://resolver.tudelft.nl/uuid:66cbbcaa-4e08-4ed0-8fc9-6782c6e28a14","Cycling fiber metal laminates: Considerations, test setup and results","Müller, B.; Teixeira De Freitas, S.; Sinke, J.","","2015","The development of fiber metal laminates to multi-functional materials by embedding heater elements in the laminate extends their field of application. Fiber metal laminates with embedded heater elements are likely to be used for the de- and anti-icing of leading edges in aircraft as they combine structural and heating functions. Hence, those heated fiber metal laminates are exposed to frequent temperature changes when the de- or anti-icing devices are switched on. In order to examine the possible effects of thermal fatigue loading on the material characteristics, a thermal cycling setup was developed. The experimental setup has the ability to perform thermal cycling tests of materials with and without embedded heater elements. For structural materials, the thermal cycling setup provides external cooling and external heating using Peltier elements. For multi-functional materials (materials with embedded heater elements), the experimental setup enables thermal cycling tests by providing external cooling using Peltier elements and internal heating using the embedded heater mesh. The multi-functional material which is thermal cycled in this study is heated GLARE (Glass Laminate Aluminum Reinforced Epoxy). The temperatures recorded by thermo couples at different specimen positions are presented. The thermal cycle times were about 62 s for temperature cycles from 0°C to 60°C and 2 mm thick heated GLARE specimens. Similar thermal cycling times can be reached for both external cooling and heating and external cooling and internal heating. However, the use of Peltier elements to heat the specimens outer surfaces (external heating) leads to more homogeneous temperature distributions than when using the embedded heater elements as internal heating. The presented experimental setup can be adapted to different specimen dimensions, enables thermal cycling of multiple specimens of the same material, and is applicable for different temperature ranges and heating or cooling rates.","fiber metal laminates; GLARE; thermal cycling; thermal fatigue; moderate temperatures; heater elements; test setup","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:7b821f51-8fd7-43ee-aedf-1bbd3a3e6b54","http://resolver.tudelft.nl/uuid:7b821f51-8fd7-43ee-aedf-1bbd3a3e6b54","An Analytical Model of Wake Deflection Due to Shear Flow","Micallef, D.; Simao Ferreira, C.J.; Sant, T.; Van Bussel, G.J.W.","","2010","The main motivation behind this work is to create a purely analytical engineering model for wind turbine wake upward deflection due to shear flow, by developing a closed form solution of the velocity field due to an oblique vortex ring. The effectiveness of the model is evaluated by comparing the results with those of a free-wake model. The solution of the velocity field due to an oblique vortex ring is obtained by using the result of an upright ring along with an equivalent point method. The wake model is derived using oblique ring elements with a number of suitable assumptions. Results of wake vertical deflection are compared with a free-wake solution. A linear trend between wake deflection and shear flow exponent is found with both models. The oblique ring model shows some discrepancies from the free-wake result in terms of the dependence of the deflection on the reference tip speed ratio. The oblique ring model needs further refinements and validation with experimental work and is only currently suited for the determination of general wake kinematics. It however provides immediate results for a given input and can be useful in generating databases with wake geometry information.","horizontal axis wind turbines; atmospheric shear flow; vortex rings","en","conference paper","European Wind Energy Association","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:0432e683-c2b7-48c3-83af-e117fe3c4184","http://resolver.tudelft.nl/uuid:0432e683-c2b7-48c3-83af-e117fe3c4184","Evaluation of anchorage international airport using the airport business suite","Roling, P.C.","","2008","","ANC; airport; airside; capacity; noise","en","conference paper","Optimage Ltd.","","","","","","","","Aerospace Engineering","","","","",""
"uuid:421fba7d-1e3b-4fb1-89a6-5ce07d418222","http://resolver.tudelft.nl/uuid:421fba7d-1e3b-4fb1-89a6-5ce07d418222","MDO design support by integrated engineering services within a multi-agent task environment","Berends, J.P.T.J.; van Tooren, M.J.L.","","2008","","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:533e8611-b480-49b6-9632-8936a87c9829","http://resolver.tudelft.nl/uuid:533e8611-b480-49b6-9632-8936a87c9829","An unsteady adaptive stochastic finite elements uncertainty quantification method for fluid-structure interaction problems","Witteveen, J.A.S.; Bijl, H.","","2008","","uncertainty quantification; adaptive stochastic finite elements; fluid-structure interaction; unsteady problems, random parameters","en","conference paper","International Center for Numerical Methods in Engineering","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c4ea36be-e5fa-400b-b734-58bfeadcc2de","http://resolver.tudelft.nl/uuid:c4ea36be-e5fa-400b-b734-58bfeadcc2de","Temperature effects on an acoustic emission based SHM system - Applied to composite materials","Vargalui, A.; Martinez, M.J.; Zarouchas, D.; Pant, S.","","2015","This study focuses on understanding the effect of temperature variations and the position of the piezoelectric sensors with respect to fiber orientation angle, as it relates to acoustic emission wave velocity in composite structures. A hybrid panel consisting of Unidirectional Carbon Fiber (UDCF) combined with Unidirectional Glass Fiber (UDGF) along with foam-core sandwich panels with hybrid face-sheets were used for this case study. The group velocities of ultrasonic Lamb waves for three different temperatures (-40 °C, +25 °C and +70 °C) at three different positions (0°, 45° and 90° with respect to the fiber direction) were measured using an Acoustic Emission (AE) system. In order to perform the experiments, a special set-up was built consisting of an environmental chamber and a temperature cycling unit. In parallel, a Finite Element Model (FEM) was developed to simulate the wave propagation of several signals in the three aforementioned temperatures. An analytical algorithm found in the literature was used to verify the experimental results. The main findings of this work were that the Lamb wave group velocities are affected by the fiber orientation more than by temperature variations imposed on the system. In addition, it was found that the signals propagate 15 to 20 % faster in the hybrid laminate than the sandwich panel.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:cab35b25-bb41-47e2-a68d-eff8c38317f2","http://resolver.tudelft.nl/uuid:cab35b25-bb41-47e2-a68d-eff8c38317f2","A novel emergency system for low earth orbit satellites using Galileo GNSS","Gill, E.K.A.; Helderweirt, A.","","2010","Low Earth Orbit (LEO) satellites have a limited direct contact time with the stations of their ground segment. This fundamentally constraints a timeliness reaction of the mission control center in case of emergency situations onboard the LEO spacecraft. To enable such a rapid reaction to emergency situations onboard LEO satellites, it is proposed to use a Search and Rescue (SAR) beacon onboard that spacecraft to transmit an alert message via Galileo satellites which support SAR through the Cospas-Sarsat (C/S) system to the satellite mission control center. While SAR up to now is limited to terrestrial, maritime, and aviation user scenarios, this space user concept presents a novel emergency system which helps facilitating the valuable space assets which LEO satellites in many cases represent. However, such a space user system faces various technical, system, and business challenges as well as legal and regulatory issues. The frequency band assigned for the SAR system is limited to low power satellite emergency position-indicating radio beacons and is foreseen for earth-space transmissions only. The International Telecommunication Union (ITU) should agree on opening this band for space-space communication for space user distress beacons. The Distress Alerting Satellite System (DASS) and the SAR/Glonass system will also operate in this band and an agreement will be required for these as well. A visibility analysis is presented for LEO to Galileo satellites. Depending on the placement of the antenna of the distress beacon on the LEO spacecraft, between 6 and 21 Galileo satellites are visible. The space user beacon may cause interference to the current SAR system when it’s signals collide with those of Earth-bound users in time or overlap in frequency at the Galileo transponder. When they collide in time one of the signals might still be processed if one of the signal levels is significantly higher than the other. Upon sharing the same frequency, both signals could be lost in a worst case scenario. This overlap in frequency can be caused by Doppler shifts. Therefore, a Doppler analysis was performed and Doppler shifts of about ?11 kHz were identified. Next to frequency overlaps the traffic load in the adjacent channels can increase. Different methods to prevent these Doppler shifts were analyzed. To reduce system complexity and benefit from existing technology, the space user beacon could be similar to that of an Earth beacon. However, the repetition time could be increased and the frequency channel selected for the Doppler analysis is chosen such that the interference is minimal. A high level design of the SAR payload onboard the LEO satellite was performed and different protocol options were valuated.","","en","conference paper","International Astronautical Federation","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:045f1368-3964-4ac7-9626-fbb47da8f277","http://resolver.tudelft.nl/uuid:045f1368-3964-4ac7-9626-fbb47da8f277","A Multidimensional Spline Based Global Nonlinear Aerodynamic Model for the Cessna Citation II","De Visser, C.C.; Mulder, J.A.","","2010","A new method is proposed for the identification of global nonlinear models of aircraft non-dimensional force and moment coefficients. The method is based on a recent type of multivariate spline, the multivariate simplex spline, which can accurately approximate very large, scattered nonlinear datasets in any number of dimensions. The new identification method is used to identify a global nonlinear aerodynamic model of high dimensionality for the Cessna Citation II laboratory aircraft operated by the Delft University of Technology and the Netherlands National Aerospace Laboratory. The data used in the identification process consisted of millions of measurements and was accumulated during more than 250 flight test maneuvers with the laboratory aircraft. The resulting models for the aerodynamic force and moment coefficients are continuous analytical functions as they consist of sets of piecewise defined, multivariate polynomials. The identified models were validated using a subset of the flight data, with validation results showing a very close match between model and reality.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:d71bf234-d464-4d6c-a93f-0385e2de4d4f","http://resolver.tudelft.nl/uuid:d71bf234-d464-4d6c-a93f-0385e2de4d4f","Radar turbulence detection: Statistical synthesis and experimental check of adaptive algorithms","Yanovsky, F.J.; Prokopenko, I.G.; Ligthart, L.P.","","2006","","radar; turbulence detection; adaptive algorithm; statistical synthesis; remote sensing of atmosphere","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Microwave Technology and Systems for Radar","","","",""
"uuid:7ac469a5-da9c-435f-9777-c4dafdc71669","http://resolver.tudelft.nl/uuid:7ac469a5-da9c-435f-9777-c4dafdc71669","Pressure Adaptive Honeycomb: Mechanics, Modeling, and Experimental Investigation","Vos, R.; Barrett, R.","","2010","A new type of adaptive structure is presented that relies on a pressure derential to perform gross structural deformations. This structure relies on highly compliant honey-comb cells that can be pressurized externally or can rely on a pressure differential that exists at elevated altitudes. By pressurizing this honeycomb, its stiffness can be altered and deformations can be controlled by means of a restoring force. The mechanics of this pressure-adaptive honeycomb is laid out in this paper. The concept of equivalent material stiffness is introduced that assigns a Young's modulus to the honeycomb wall material that includes both the material-induced stiffness and the pressure-induced stiffness for a given cell differential pressure. The application of this model in a finite element analysis of a beam specimen is shown to correlate well to experimental results. In addition, the paper discusses possible applications for pressure adaptive honeycomb such as a Gurney flap and a solid-state flap. Wind tunnel test on a test article of a wing with pressure-adaptive flap demonstrates an increase in lift coefficient of 0.3 over a wide range of angles of attack. By increasing the pressure inside the flap to 40kPa its equivalent stiffness increases from 15kPa to 109kPa, thereby allowing the camber to decrease from 7.2% in deployed position to 2% in stowed position and shifting the point of maximum camber from 72% of the wing chord to 40%.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:3276612a-39e9-46c6-bec7-658a0cd55a96","http://resolver.tudelft.nl/uuid:3276612a-39e9-46c6-bec7-658a0cd55a96","A study of the temperature dependent healing capabilities of new polymers based on Diels-Alder cycloaddition","Kötteritzsch, J.; Hager, M.D.; Schubert, U.S.; Bose, R.K.; Garcia Espallargas, S.J.; Van der Zwaag, S.","","2013","Because of its thermal reversibility, the retro-Diels-Alder (RDA) reaction represents an appealing possibility to produce self-healing polymers with well-defined architectures and tunable properties [1]. However, the polymer architecture for which the Diels-Alder (DA) reaction can best be used to contribute to the healing process is still not well-defined. Therefore, new terpolymers containing moieties for the reversible crosslinking by the DA reaction have been synthesized. These linear polymers are based on a methacrylate backbone containing both functionalities in the side chains and represent a one component self-healing system. As a desirable consequence no separate (low molar mass) crosslinker is necessary to obtain the desired self-healing properties. A protected maleimide is used as functional comonomer which can be activated after polymerization. Upon the occurrence of local damage the crosslinked material can be heated to a certain temperature, where the retro-Diels-Alder reaction takes place and the material obtains the necessary local mobility for damage closure. Upon cooling to room temperature, the coupling of the two reactive functional groups takes place and the strength of the material is restored. The synthesis of these terpolymers with maleimide methacrylate (MIMA) and furfuryl methacrylate (FMA) as functional units for the DA cycloadditon and different co-monomers in different ratios were achieved by applying the atom transfer radical polymerization (ATRP). Besides the characterization of the obtained polymers by 1H NMR spectroscopy, SEC, and MALDI-TOF MS, the thermal properties were investigated by TGA and DSC. The damage healing was studied by AFM and SEM. To obtain further details on the healing mechanism at the nanoscale additional temperature dependent FTIR measurements during and after shear flow were made.","copolymerization; crosslinking; Diels-Alder cycloaddition; self-healing polymers; FTIR measurement","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:73327db7-40b7-4a47-9dec-a12d69098b7e","http://resolver.tudelft.nl/uuid:73327db7-40b7-4a47-9dec-a12d69098b7e","Automated detection of branch dimensions in woody skeletons of leafless fruit tree canopies","Bucksch, A.; Fleck, S.","","2009","Light driven physiological processes of tree canopies need to be modelled based on detailed 3Dcanopy structure – we explore the possibilities offered by terrestrial LIDAR to automatically represent woody skeletons of leafless trees as a basis for adequate models of canopy structure. The automatic evaluation method for LIDAR data of fruit trees is based on a previously developed skeletonization algorithm. Branch length was chosen as example parameter to test the performance of the algorithm with manually measured data. The extraction of the brach length utilizes a graph splitting procedure to extract the individual branches from the skeleton. The algorithm is validated against six leafless apple trees and one cherry tree with small blossoms. The validation against a manually measured ground truth resulted in a good correlation up to 0.81.","terrestrial laser scanning; canopy analysis; point cloud; skeleton","en","conference paper","","","","","","","","","Aerospace Engineering","DEOS","","","",""
"uuid:1c71d304-e9a4-469e-bab0-246da8859a57","http://resolver.tudelft.nl/uuid:1c71d304-e9a4-469e-bab0-246da8859a57","Estimating the frequency dependent behavior of marine sediment sound speeds using low frequency aircraft sound","Amiri-Simkooei, A.; Snellen, M.; Simons, D.G.; Buckingham, M.","","2008","","","en","conference paper","Société Française d'Acoustique","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:34ec47a4-378c-498f-be60-dfe74ee53991","http://resolver.tudelft.nl/uuid:34ec47a4-378c-498f-be60-dfe74ee53991","Re-design of an Inbound Planning Interface for Air Traffic Control","Klomp, R.E.; Mulder, M.; Van Paassen, M.M.; Roerdink, M.I.","","2011","In the coming decades, the task of an air traffic controller is expected to shift to one of strategic, trajectorybased air traffic management. This form of air traffic control is no longer possible without the help of automated support tools. In previous research, it has been shown that the time-space diagram, combined with a conventional plan view display is a good candidate for supporting an air traffic controller with the inbound planning task in the future situation. However, in this initial study, the vertical plane was not yet fully included. Secondly, during an initial validation experiment, creating and maintaining a ’mental picture’ of the traffic was reported to be a difficult task. These findings lead to the re-design of the interface in the current research, which focuses on implementing the vertical plane and improving the integration of information across the successive displays. An experiment has been performed with a PC-based simulation which validates that the enhanced interface can be used to manage the air traffic safely and efficiently. Secondly, it has been shown that the ability to manipulate the speed of an aircraft in the adjacent sector can significantly increase situation awareness and reduce controller workload.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:52fe752e-259e-40fc-af6e-e1c77d542941","http://resolver.tudelft.nl/uuid:52fe752e-259e-40fc-af6e-e1c77d542941","Material selection and joining methods for the purpose of a high-altitude inflatable kite","Verheul, R.F.; Breukels, J.; Ockels, W.J.","","2009","This paper discusses the requirements for fabrics and joints for use in a long-endurance, high-altitude inflatable kite. Calculations of the expected stresses as well as the consequences of scaling with respect to these stresses are discussed. An overview is given of currently available kite fabrics and their joining methods. Suitable fabrics and joining methods from the sailing and aerospace industry are evaluated. The results of several tests on both fabrics and joints are presented.","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:250aeafe-c72e-48ed-abcb-32192e132edd","http://resolver.tudelft.nl/uuid:250aeafe-c72e-48ed-abcb-32192e132edd","The future of offshore wind turbines","Ashuri, T.; Zaayer, M.B.","","2007","","","en","conference paper","European Academy of Wind Energy EAWE","","","","","","","","Aerospace Engineering","","","","",""
"uuid:54e449f6-2759-4286-8b48-d258bcb6c3a2","http://resolver.tudelft.nl/uuid:54e449f6-2759-4286-8b48-d258bcb6c3a2","The Development and Application of a Value-Driven Aircraft Maintenance Operations Performance Assessment Model combined with Real Options Analysis","Goossens, H.G.; Beelaerts van Blokland, W.W.A.; Curran, R.","","2011","This research paper presents the results from the development of an Aircraft Maintenance Operations Performance Assessment Model (AMOPAM). The AMOPAM is able to assess the differences in performance in between two different states or scenarios of aircraft maintenance operations and is able to capture these differences both in the form of differential- (?V) and financial value (NPV). The AMOPAM is based on the combination of the Value Operations Methodology and Real Options Analysis. The input variables are Key Performance Indicators that have been identified as value drivers that can capture the operational and financial performance of aircraft maintenance procedures. The model is validated at a real life case at the aircraft maintenance department from KLM (Royal Dutch Airlines) E&M (Engineering and Maintenance). Hereby it was used to evaluate improvement opportunities for its recovery processes used in case of material unavailability. A regression analysis of the results of the case study has indicated a relationship between NPV and differential value. This has offered new insight in how the performance of aircraft maintenance operations can be assessed and how value can be interpreted from an operational and financial perspective.","Aircraft Maintenance; Operations Performance Assessment Methodologies (OPAM); Value Operations Methodology (VOM); Real Options Analysis (ROA)","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:f9aab449-cafc-447c-9979-a7999b2c713a","http://resolver.tudelft.nl/uuid:f9aab449-cafc-447c-9979-a7999b2c713a","Is Time a creation of Life in response to Gravity?: This hypothesis suggests new ways for looking at extraterrestrial life","Ockels, W.J.","","2007","From his personal experience during a space flight (Challenger 1985) onward, the author has been struck repeatedly by the remarkable influence of Earth's environment on life, in particular by its most inevitable elements: time and gravity. Our life might be peculiar to the local Earth conditions, and not cosmic per se. In this article the hypothesis is postulated that our ‘speed’ of life, in relation to the speed of information (in this case the speed of light), is specific to humankind. Life is the process that ‘makes’ time. In this approach the constancy of the speed of light is not so much a property of the external world, but rather a consequence of our getting older at a fixed ‘time-speed’. We are sitting in a ‘time train’ and all the information that we observe from the outside world is travelling relative to us at the same speed as our train. The train speed is, in a sense, the speed of light. If that is the case, then the expanding universe is an illusion. The remnants of the ‘big bang’ are standing ‘still’ while we move away and see all distances increasing. It is also shown in this article that there is a relationship between this time-speed and gravity, and that it can be the result of a process in the brain. By interpreting gravity as the result of a rotating motion, rather than a linear upward acceleration, time is introduced. In today’s science we consider all universal processes in respect to our present (= now). In fact, we believe that the universe started 13.6 billion years ago. This approach to science is set against the history of centralism: from the geocentrism of Ptolemy to the heliocentrism of Galilei, extrapolated to the ‘chronocentrism’ of today. An intriguing consequence of this theory is that extraterrestrial life would have a different speed of light. To couch this in a metaphor: we are living in a green world and see only green, while the others live in a red world and see only red. Each of these worlds can be part of one system, but we cannot see each other. Ideas are presented on how one might be able to communicate with these extraterrestrial living systems. Based on the assumption that different time propagations are still made up from the same time quanta, but with different lengths of empty time in between, one can imagine that those time speeds could be transferred by a ‘replay’ at our speed, like the frames in a film. Following the same assumption, a Lorentz transformation could connect both worlds, implying that the signals from another world would, for us, be split into two signals, each with a different time speed and distance speed not corresponding to our speed of light. Detecting those two signals simultaneously could lead to an intriguing experiment.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:9d37eb50-3f84-4122-94ae-38d5bc65d8c8","http://resolver.tudelft.nl/uuid:9d37eb50-3f84-4122-94ae-38d5bc65d8c8","Roof plane extraction in gridded digital surface models","Gorte, B.","Kolbe, T.H. (contributor); Zhang, H. (contributor); Zlatanova, S. (contributor)","2009","With the rapid improvement of LIDAR systems regarding point density and accuracy in relation to the (application dependent) requirements, robustness, efficiency and automation of the modeling process are becoming more important than achieving the highest possible accuracy and modeling detail from the available LIDAR data. Therefore we opt for development of a 2D grid based LIDAR data analysis approach. An important step is detection and parameterization of planar surfaces (roof elements). The paper reviews four methods, based on analysis of gradients, principal components, least squares and hough transforms, respectively. It introduces a series of improvements to the standard usage of each of those methods and shows results from synthetic and real data.","","en","conference paper","International Society of Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1d15d953-2acc-4cd0-8dc2-7cfb253bc356","http://resolver.tudelft.nl/uuid:1d15d953-2acc-4cd0-8dc2-7cfb253bc356","Adaptive aerostructures: The first decade of flight on uninhabited aerial vehicles","Barrett, R.","","2004","Although many subscale aircraft regularly fly with adaptive materials in sensors and small components in secondary subsystems, only a handful have flown with adaptive aerostructures as flight critical, enabling components. This paper reviews several families of adaptive aerostructures which have enabled or significantly enhanced flightworthy uninhabited aerial vehicles (UAVs), including rotary and fixed wing aircraft, missiles and munitions. More than 40 adaptive aerostructures programs which have had a direct connection to flight test and/or production UAVs, ranging from hover through hypersonic, sea-level to exo-stratospheric are examined. Adaptive material type, design Mach range, test methods, aircraft configuration and performance of each of the designs are presented. An historical analysis shows the evolution of flightworthy adaptive aerostructures from the earliest staggering flights in 1994 to modern adaptive UAVs supporting live-fire exercises in harsh military environments. Because there are profound differences between bench test, wind tunnel test, flight test and military grade flightworthy adaptive aerostructures, some of the most mature industrial design and fabrication techniques in use today will be outlined. The paper concludes with an example of the useful load and performance expansions which are seen on an industrial, military-grade UAV through the use of properly designed, flight-hardened adaptive aerostructures.","piezoelectric; shape memory alloy; adaptive; flight control; uninhabited aerial vehicle","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","","","","",""
"uuid:efbdabaf-e7ae-4a52-a371-3b27d31761f9","http://resolver.tudelft.nl/uuid:efbdabaf-e7ae-4a52-a371-3b27d31761f9","The trail of six design projects in the Delft bachelor Aerospace Engineering","Kamp, A.","","2012","Tomorrow’s engineers are required to have a good balance between deep working knowledge of engineering sciences and engineering skills. In the Bachelor Aerospace Engineering at TU Delft, students are educated to master these competences so that they are ready to engineer when they graduate. The bachelor curriculum has three mainstreams of about equal study load: Aerospace Design, Aerospace Engineering & Technology, and Basic Engineering Sciences. The Aerospace Design stream is built up semester after semester of a design project and an accompanying design course. The main objectives of the design projects are related to contextual learning, to being a mental organiser for the students, to learning by doing together, and to learning and practicing academic and engineering skills. Over the years of study the design projects increase in complexity and openness, from knowing to application, synthesis and evaluation, from tangible to abstract, from mono- to multidisciplinary, from mostly individual to team work. All projects exploit the factors that promote intrinsic motivation (challenge, curiosity, control, fantasy, competition, cooperation, and recognition). To assure that the intrinsic motivation factors and the semester themes are well addressed, each design project is characterised by a storyline, professional role, client, real-life problem, engineering process, and certain attainment levels of engineering skills. The projects make use of 45 well-equipped student project spaces in a dedicated building and laboratories like wind tunnels, a structures and materials laboratory, a study collection of aircraft and spacecraft parts and subsystems, and a flight simulator. The organisation of the six design projects for 300-440 students per project challenges the resources of the academic staff and the logistics of the project and lab spaces.","project education; project-based learning; experiential learning; aerospace engineering; design education; integrated curriculum","en","conference paper","CDIO","","","","","","","","Aerospace Engineering","Support Aerospace Engineering","","","",""
"uuid:ac6cdb54-f4ad-4e47-b794-8ece592782bd","http://resolver.tudelft.nl/uuid:ac6cdb54-f4ad-4e47-b794-8ece592782bd","Quantifying the lean value network system; the lean value creation metrics of networked organizations","Beelaerts van Blokland, W.W.A.; Fiksinski, M.A.; Amoa, S.O.B.; Santema, S.C.","","2008","","lean metrics; value network system; co-innovation","en","conference paper","Industrial Marketing and Purchasing Group","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6f6e50c9-71f6-41ed-8d25-566fcf211a10","http://resolver.tudelft.nl/uuid:6f6e50c9-71f6-41ed-8d25-566fcf211a10","Application of Powell's analogy for the prediction of vortex-pairing sound in a low-Mach number jet based on time-resolved planar and tomographic PIV","Violato, D.; Bryon, K.; Moore, P.; Scarano, F.","","2010","This paper describes an experimental investigation by time-resolved planar and tomographic PIV on the sound production mechanism of vortex pairing of a transitional water-jet flow at Re=5000. The shear layer is characterized by axisymmetric vortex rings which undergo pairing with a varicose mode. Three-dimensional measurements show the presence of longitudinal pairs of counter-rotating vortices inducing vortex azimuthal instabilities prior to the breakdown of the vortices. Based on Powell's aeroacoustic analogy, flow structures responsible for noise generation are characterized by the second-time-derivative of the Lamb vector field, which is directly evaluated by planar and tomographic PIV. The analysis of the dynamics of such structures shows peak activity in correspondence of the vortex cores during the leapfrogging, vortex-azimuthal instabities and vortex breakdown mechanism. Under the hypothesis of axisymmetric flow, far field acoustic produced by vortex pairing is predicted by directly applying time-resolved planar PIV data to Powell's acoustic analogy. Pronounced acoustic emission is found during the coalescence of the vortices.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:f82b5a26-f193-4a19-a1cd-8ee6c418f3be","http://resolver.tudelft.nl/uuid:f82b5a26-f193-4a19-a1cd-8ee6c418f3be","A new method for individual tree delineation and undergrowth removal from high resolution airborne LiDAR","Abd Rahman, M.Z.; Gorte, B.G.H.; Bucksch, A.K.","","2009","High density airborne LiDAR, for example FLI-MAP 400 data, has opened an opportunity for individual tree measurement. This paper presents a method for individual tree delineation and undergrowth vegetation removal in forest area. The delineation of individual trees involves two steps namely 1) tree crown delineation based on density of high points (DHP) and 2) separation of dominant trees and undergrowth vegetation. The DHP method relies on the fact that the density of received laser pulses above a certain height is high at the centre of a tree crown and decreases towards the edge of the crown. In the second step, a special tree filtering algorithm is introduced to remove undergrowth vegetation, which is necessary to ease for instance the measurement of tree diameter at breast height (DBH). Two study sites are selected and the tree delineation method is tested under different tree conditions. It is shown that the method has successfully delineated more than 60% trees. However it failed to delineate the trees in two cases 1) undergrowth vegetation is very near to the dominant trees and it is even hard to separate it manually, or 2) the LiDAR data failed to reflect the complete structure of a dominant tree due to forest interception.","airborne LiDAR; individual tree delineation; undergrowth vegetation; density of high points (DHP); region growing (RG)","en","conference paper","ISPRS","","","","","","","","Aerospace Engineering","","","","",""
"uuid:59c02392-1aaf-4c13-ab18-590d492e7fc8","http://resolver.tudelft.nl/uuid:59c02392-1aaf-4c13-ab18-590d492e7fc8","Active Aerodynamic Blade Distributed Flap Control Design Procedure for Load Reduction on the UpWind 5MW Wind Turbine","Wilson, D.G.; Resor, B.R.; Berg, D.E.; Barlas, T.K.; Van Kuik, G.A.M.","","2010","This paper develops a system identification approach and procedure that is employed for distributed control system design for large wind turbine load reduction applications. The primary goal of the study is to identify the process that can be used with multiple sensor inputs of varying types (such as aerodynamic or structural) that can be used to construct state-space models compatible with MIMO modern control techniques (such as LQR, LQG, H1, robust control, etc.). As an initial step, this study employs LQR applied to multiple flap actuators on each blade as control inputs and local deflection rates at the flap spanwise locations as measured outputs. Future studies will include a variety of other sensor and actuator locations for both design and analysis with respect to varying wind conditions (such as high turbulence and gust) to help reduce structural loads and fatigue damage. The DU SWAMP aeroservoelastic simulation environment is employed to capture the complexity of the control design scenario. The NREL 5MW UpWind reference wind turbine provides the large wind turbine dynamic characteristics used for the study. Numerical simulations are used to demonstrate the feasibility of the overall approach. This study shows that the distributed controller design can provide load reductions for turbulent wind profiles that represent operation in above-rated power conditions.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:0d8a5de7-966a-4f80-bc5c-bc6bb1733410","http://resolver.tudelft.nl/uuid:0d8a5de7-966a-4f80-bc5c-bc6bb1733410","Design and Manufacture of a Variable-Stiffness Cylindrical Shell","Blom, A.W.; Stickler, P.B.; Gurdal, Z.","","2009","","","en","conference paper","SAMPE Europe","","","","","","","","Aerospace Engineering","Aerospace Structures & Design Methodology","","","",""
"uuid:4a16c66d-0ea1-4a66-be0b-e4a678ba428d","http://resolver.tudelft.nl/uuid:4a16c66d-0ea1-4a66-be0b-e4a678ba428d","Time-based Spacing for 4D Approaches using Speed-Profiles","De Jong, P.M.A.; De Vos, K.; Borst, C.; Van Paassen, M.M.; Mulder, M.","","2011","Two of the major projects in ATM development, SESAR and NextGen, both fore- cast the use of 4D trajectories as an intermediate phase in the development of full Performance Based Trajectories. Using 4D trajectories, the full positional and time coordinates of the aircraft are known throughout the planned trajectory. During approach, when reduced separation minimums are applied, the accuracy of this profile is most important to ensure a safe approach to the runway. One implementation of 4D approaches is by using Required-Time of Arrival (RTA) to separate aircraft during approach. The latest Flight Management Computers are capable of calculating a flight-path w.r.t. to a RTA. This paper describes the amount of time error that can occur during approaches where an RTA is set at the runway threshold that could still be resolved by increasing or decreasing the speed-profile. The minimum and maximum bounds are referred to as control space. Using simulations, the recoverable time error is calculated. Lateral trajectories from Amsterdam Airport Schiphol, different wind conditions and two different aircraft types were included to investigate different factors influencing the time error, such as aircraft type, speed restrictions and wind. Finally, the paper discusses a new method to control time-based spacing using a closed-loop speed controller.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:5db7b1b0-a4fc-4fd0-b411-296988708efd","http://resolver.tudelft.nl/uuid:5db7b1b0-a4fc-4fd0-b411-296988708efd","Three-dimensional simulation of a Laddermill","Podgaets, A.R.; Ockels, W.J.","","2006","","Laddermill; multi-body dynamics; sustainable","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b739bd05-c5bc-4ffa-aedb-318726f15e34","http://resolver.tudelft.nl/uuid:b739bd05-c5bc-4ffa-aedb-318726f15e34","Incidence angle influence on the quality of terrestrial laser scanning points","Soudarissanane, S.; Lindenbergh, R.; Menenti, M.; Teunissen, P.J.G.","","2009","A terrestrial laser scanner measures the distance to an object with a precision in the order of millimeters. The quality of each single point in a point cloud affects post-processing applications, such as deformation analysis or 3D modeling. The quality of a scan point is influenced by four major factors: instrument calibration, atmospheric conditions, object properties and scan geometry. In this paper, the latter factor is investigated focusing on the influence of incidence angle, i.e. the angle between incoming laser beam and surface normal, on the precision of a scan point. It is shown that by considering the influence of incidence angle on the signal to noise ratio, the increase in measurement noise with increasing incidence angle can be successfully modeled. The implications of this model are demonstrated on two practical experiments. In the first experiment, a reference plate is scanned at a fixed distance but under different scan angles. The analysis shows that also in a practical setting the influence of incidence angle could be successfully isolated, allowing the conclusion that above 60º the incidence angle dominates the scan point precision. In the second experiment it is demonstrated that for a typical point cloud of a room, 20% of the measurement noise is due to incidence angle. The results of this research make it feasible to optimize the scan locations in a measurement setup in the sense that noise due to incidence angle is minimized.","laser scanning; incidence angle; individual point quality; measurement setup","en","conference paper","ISPRS","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:bbd09e81-e3e7-4b04-80d4-8714cfcfbb30","http://resolver.tudelft.nl/uuid:bbd09e81-e3e7-4b04-80d4-8714cfcfbb30","Effect of chordwise deformation on unsteady aerodynamic mechanisms in hovering flapping flight","Noyon, T.A.; Tay, W.B.; Van Oudheusden, B.W.; Bijl, H.","","2014","A three-dimensional simulation of hovering flapping wings was performed using an immersed boundary method. This was done to investigate the effects of chordwise wing deformation on three important unsteady aerodynamic mechanisms found in flapping flight, namely Leading Edge Vortex (LEV) shedding, wake capture and clap and fling. A wing was modeled as a flat plate, flapping close to a symmetry plane. Three different deforming chords were defined, a rigid case, a case with maximum deformation at the trailing edge and increased angle of attack (AoA) near the leading edge, and a case with the maximum deformation in the center of the chord and decreased AoA near the leading edge. All cases had zero deformation at the wing root and maximal deformation at the wing tip. A higher AoA near the leading edge resulted in faster LEV buildup and faster buildup of lift. No shedding of the LEV was observed in any of the cases even when deformation caused a high AoA near the leading edge. A distinct dip in lift buildup was observed and shown to be caused by the interaction between the previously shed vortex and the newly developing LEV. This interaction occurred faster when the AoA at the leading edge was increased, and slower when the angle of attack was decreased. Moving the wing closer to the symmetry plane had a positive effect on the cycle average value of CL. This positive effect was reduced however by the earlier interaction between the LEV and the previously shed vortex.","Micro Air Vehicle; flapping flight; hovering","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:d1b1b87d-e7e0-4c41-83e2-f6db067db2c9","http://resolver.tudelft.nl/uuid:d1b1b87d-e7e0-4c41-83e2-f6db067db2c9","Application of constrained stochastic simulation to determine the extreme response of wind turbines","Bierbooms, W.A.A.M.; Peeringa, J.","","2009","Up to now just deterministic gust shapes are specified in standards; e.g. the Extreme Operating Gust (IEC) is given by a Mexican hat like shape. In this paper gust shapes will be determined by application of so-called constrained stochastic simulation. This method specifies how to efficiently generate time series around some specific event (e.g. a local maximum) in a normal (Gaussian) process. In this way the generated gusts have the correct stochastic properties of turbulence (like generated wind fields for fatigue analysis). In constrained stochastic simulation a random signal can be generated which satisfies some condition, e.g. a maximum value or jump at some time instant. Usually the condition is applied on the external condition, i.e. the wind or waves (for offshore wind turbines). In this paper the condition of a maximum value, at some time instant, will be applied to the response instead (the blade root flapping moment). Assuming a linearised model of the wind turbine, the accompanying wind input leading to the extreme response, can be derived. By performing load simulations the proposed method is validated. In the future a probabilistic approach of extreme loading may replace the present deterministic procedure in standards.","Wind field simulation; Gust models; Constrained stochastic simulation; Extreme conditions","en","conference paper","European Wind Energy Association, EWEA","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:c3551b12-3862-47ff-a23e-923289ad23ed","http://resolver.tudelft.nl/uuid:c3551b12-3862-47ff-a23e-923289ad23ed","Numerical simulation of 'X-wing' type biplane flapping wings in 3D using the Immersed Boundary Method (IBM)","Tay, W.B.; Van Oudheusden, B.W.; Bijl, H.","","2013","The numerical simulation of a “X-wing” type biplane flapping wings, has been performed in 3D using the Immersed Boundary Method (IBM). This “X-wing” type flapping configuration draws its inspiration from Delfly [1], a family of ornithopters developed by the Delft University of Technology, as shown in Figure 1. The unique “X-wing” design features a biplane flapping wings where two sets of wings were are placed above each other moving in counter phase. On comparison with configurations using a single pair of wings or two sets of wings in tandem, experiments showed that the “X-wing” configuration gives lower power requirement and zero rocking amplitude, which is a beneficial property for a Flapping Micro Aerial Vehicle (FMAV) to be used as a camera platform.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:d6a94fa5-5e07-41bc-a169-2dbb6985b24b","http://resolver.tudelft.nl/uuid:d6a94fa5-5e07-41bc-a169-2dbb6985b24b","Modeling of particle imaging through shock waves","Elsinga, G.E.; Van Oudheusden, B.W.; Scarano, F.","","2005","In compressible flows particle imaging, as done in Particle Image Velocimetry (PIV), is far from trivial. The inhomogeneous refractive index field can cause aero-optical aberrations including blurring of the image, especially near optical interfaces such as shock waves. The understanding of the process causing particle image blur (or blurring of the point spread function of the imaging system) is important in order to assess the measurement accuracy of optical measurement systems, such as PIV. A model for imaging through a shock wave is presented to determine the characteristic shape of blurred particle images when imaged across shock waves. The conjectured model is validated through a PIV experiment, where particle image recordings of the flow across a steady oblique shock wave are obtained in a supersonic wind tunnel. The parametric study focuses on two dominating parameters: 1) the angle between the viewing axis and the shock wave; 2) the numerical aperture of the imaging optics.","aero-optics; shock waves; PIV; point spread function; particle image blur","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:d718fd38-00b9-4bb0-8729-01fde1d6d711","http://resolver.tudelft.nl/uuid:d718fd38-00b9-4bb0-8729-01fde1d6d711","Time-resolved image analysis for turbulent flows","Kähler, C.J.; Cierpka, C.; Scharnowski, S.; Manhart, M.; Sciacchitano, A.; Lynch, K.; Scarano, F.; Wieneke, B.; Willert, C.; Jeon, Y. J.; Chatellier, L.; Augereau, L.; Tremblais, B.; David, L.","","2013","Classical Particle Image Velocimetry (PIV) uses two representations of the particle image distribution to determine the displacement of the particle image pattern by spatial cross-correlation. The accuracy and the robustness are however limited by the fact that only two representations at t and t +?t are present. Thus, only a first order approximation of the velocity can be estimated. To enhance the precision in estimating the flow velocity, multi-pulse or multi-frame techniques were already investigated in the early days of PIV as summarized by Adrian (1991) and Hain and Kähler (2007). Today with the increasing power of high repetition rate lasers and enhanced sensitivity of the digital cameras it is possible to have a time-resolved sampling of even aerodynamically relevant flows, were the particles are much smaller than in water flows. The easiest sampling scheme is the equidistant temporal sampling of the particle distribution such that a robust displacement estimation between successive frames (1+2, 2+3, 3+4,
) is possible. This so called TR-PIV does not only provide the possibility to follow the evolution of flow structures, but offers the ability to strengthen the data processing by using information from more than two frames (e.g. Hain and Kähler, 2007). Within the AFDAR-project (Advanced Flow Diagnostics for Aeronautical Research funded by the European Union) different approaches to evaluat time-resolved image series were developed by the different groups. The current contribution focuses on the comparison of the algorithms that were developed within the AFDAR project by the partners of the consortium. To verify and validate the performance of the different algorithms a short image sequence of an experiment on the flow over periodic hills (ERCOFTAC test case 81) was provided to all partners and evaluated with the current version of the algorithms.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:20834908-3268-4295-9163-93daeaf00ca1","http://resolver.tudelft.nl/uuid:20834908-3268-4295-9163-93daeaf00ca1","System ID Modern Control Algorithms for Active Aerodynamic Load Control and Impact on Gearbox Loading","Berg, D.; Wilson, D.; Resor, B.; Berg, J.; Barlas, J.; Crowther, A.; Halse, C.","","2010","Prior work on active aerodynamic load control (AALC) of wind turbine blades has demonstrated that appropriate use of this technology has the potential to yield significant reductions in blade loads, leading to a decrease in wind cost of energy. While the general concept of AALC is usually discussed in the context of multiple sensors and active control devices (such as flaps) distributed over the length of the blade, most work to date has been limited to consideration of a single control device per blade with very basic Proportional Derivative controllers, due to limitations in the aeroservoelastic codes used to perform turbine simulations. This work utilizes a new aeroservoelastic code developed at Delft University of Technology to model the NREL/Upwind 5 MW wind turbine to investigate the relative advantage of utilizing multiple-device AALC. System identification techniques are used to identify the frequencies and shapes of turbine vibration modes, and these are used with modern control techniques to develop both Single-Input Single-Output (SISO) and Multiple-Input Multiple-Output (MIMO) LQR flap controllers. Comparison of simulation results with these controllers shows that the MIMO controller does yield some improvement over the SISO controller in fatigue load reduction, but additional improvement is possible with further refinement. In addition, a preliminary investigation shows that AALC has the potential to reduce off-axis gearbox loads, leading to reduced gearbox bearing fatigue damage and improved lifetimes.","active aerodynamic load control; smart blades; distributed control; dynamic simulation; gearbox fatigue life","en","conference paper","European Wind Energy Association","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:e9b7e9fe-d4a1-4446-8757-dd7aaead9ec0","http://resolver.tudelft.nl/uuid:e9b7e9fe-d4a1-4446-8757-dd7aaead9ec0","Dynamic system simulation of small satellite projects","Raif, M.; Walter, U.; Bouwmeester, R.","","2009","A prerequisite to accomplish a system simulation is to have a system model holding all necessary project information in a centralized repository that can be accessed and edited by all parties involved. At the Institute of Astronautics of the Technische Universitaet Muenchen a modular approach for modeling and dynamic simulation of satellite systems has been developed called Dynamic System Simulation (DySyS). DySyS is based on the platform independent description language SysML to model a small satellite project with respect to the system composition and dynamic behavior. A library of specific building blocks and possible relations between these blocks have been developed. From this library a system model of the satellite of interest can be created. A mapping into a C++ simulation allows the creation of an executable system model with which simulations are performed to observe the dynamic behavior of the satellite. In this paper DySyS is used to model and simulate the dynamic behavior of small satellites, because small satellite projects can act as a precursor to demonstrate the feasibility of a system model since they are less complex compared to a large scale satellite project.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:2470b744-ce1f-4cfc-b268-d8987cfb4bd4","http://resolver.tudelft.nl/uuid:2470b744-ce1f-4cfc-b268-d8987cfb4bd4","Optic-flow based slope estimation for autonomous landing","De Croon, G.C.H.E.; Ho, H.W.; De Wagter, C.; Van Kampen, E.; Remes, B.; Chu, Q.P.","","2013","Micro Air Vehicles need to have a robust landing capability, especially when they operate outside line-of-sight. Autonomous landing requires the identification of a relatively flat landing surface that does not have too large an inclination. In this article, a vision algorithm is introduced that fits a second-order approximation to the optic flow field underlying the optic flow vectors in images from a bottom camera. The flow field provides information on the ventral flow (vx/h), the time-to-contact (h/ ? vz), the flatness of the landing surface, and the surface slope. The algorithm is computationally efficient and since it regards the flow field as a whole, it is suitable for use during relatively fast maneuvers. The algorithm is subsequently tested on artificial image sequences, hand-held videos, and on the images made by a Parrot AR drone. In a preliminary robotic experiment, the AR drone uses the vision algorithm to determine when to land in a scenario where it flies off a stairs onto the flat floor.","","en","conference paper","","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:e2613d94-6831-4ea0-b148-a395e1551118","http://resolver.tudelft.nl/uuid:e2613d94-6831-4ea0-b148-a395e1551118","Continuous rating of perceived visual-inertial motion incoherence during driving simulation","Cleij, D.; Venrooij, J.; Pretto, P.; Pool, D.M.; Mulder, M.; Bülthoff, H.H.","","2015","Motion cueing algorithms (MCA) are used in motion simulation to map the inertial vehicle motions onto the simulator motion space. To increase fidelity of the motion simulation, these MCAs are tuned to minimize the perceived incoherence between the visual and inertial motion cues. Despite time-invariant MCA dynamics the incoherence is not constant, but changes over time. Currently used methods to measure the quality of an MCA focus on the overall differences between MCAs, but lack the ability to detect how quality varies over time and how this influences the overall quality judgement. This paper describes a continuous subjective rating method with which perceived motion incoherence can be detected over time. An experiment was performed to show the suitability of this method for measuring motion incoherence. The experiment results were used to validate the continuous rating method and showed it provides important additional information on the perceived motion incoherence during a simulation compared to an offline rating method.","driving; simulation; motion; cueing; evaluation","en","conference paper","Max Planck Institute for Biological Cybernetics","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:5c509971-5205-453d-9b83-731af0b1dea2","http://resolver.tudelft.nl/uuid:5c509971-5205-453d-9b83-731af0b1dea2","Rotorcraft-pilot coupling research in Europe: A success story in collaboration","Dieterich, O.; Pavel, M.D.","","2015","For augmented helicopters with modern flight control systems, unintended and unexpected oscillations or divergences of the pilot-rotorcraft system have become an increasingly critical issue. Especially the rapid advances in the field of high response actuation and highly augmented flight control systems have increased the sensitivity to aspects that lead to unfavourable Aircraft-Pilot Coupling (APC) and Rotorcraft-Pilot Coupling (RPC). The understanding, prediction and prevention of adverse RPCs is a challenging task requiring the analysis and simulation of the complete closed loop system consisting of pilot – control system – rotorcraft. In Europe, comprehensive research activities were launched by the GARTEUR HC AG-16 action group (2005-2008) in order to improve the physical understanding of RPCs. Overall objectives of GARTEUR HC AG-16 were the definition of criteria for quantifying the helicopters’ susceptibility to RPC and the establishment of guidelines for preventing or suppressing critical RPC incidents in future, thus contributing to increased helicopter operational safety. The GARTEUR research was further continued under the umbrella of the 7th European Framework Programme (FP7) in the project ARISTOTEL - Aircraft and Rotorcraft Pilot Couplings – Tools and Techniques for Alleviation and Detection (2010-2013). Regarding numerous flight events in the past, several types of RPCs have been observed which can be differentiated by the frequency contents as well as by the underlying physics and human behaviour. Focus in the GARTEUR HC AG-16 group was given on the one hand to RPC phenomena in the frequency range up to approximately 1 Hz and on the other hand to coupling phenomena approximately between 2 Hz and 5 Hz. This paper presents an overview of the various numerical and experimental activities of research. Selected results are highlighted and discussed demonstrating the used approach to investigate different RPC phenomena in a schematic manner.","","en","conference paper","NVvL","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:87548511-912c-4c4c-adb9-cfdbd6ac48a0","http://resolver.tudelft.nl/uuid:87548511-912c-4c4c-adb9-cfdbd6ac48a0","The Effect of Synthetic Vision Enhancements on Landing Flare Performance","Le Ngoc, L.; Borst, C.; Mulder, M.; Van Paassen, M.M.","","2010","The usage of heads-down, non-conformal synthetic vision displays for landings below minimums has inherent problems during the flare due to minification effects. Literature showed that pilots can use four visual cues to perform a manual flare maneuver. Amongst their strategies, the Jacobson flare method seemed the most suitable to provide flare initiation and flare control cues. Offline, linear simulation results indicated that the Jacobson method was robust and its performance was comparable to an automatic landing system. An enhanced synthetic vision display was designed offering support cues to aid pilots with this landing method. An experiment was conducted in a fixed-based simulator with eight professional pilots and eight novice pilots. The enhanced display was tested against a basic version and conventional primary flight display with outside visuals. Each pilot group was split into two groups with different display orders to check for possible learning effects. The experiment showed that touchdown position was not affected by display type. The enhanced display did achieve softer touchdown sink rates compared to the basic version. The softest landings were done on outside visuals. A strong learning curve was also observed for the group of pilots that first flew with the enhanced display: this translated into better achieved performances with subsequent displays. Therefore, it could be a valuable tool for basic flight training and reduce the number of flight hours required in mastering the landing flare.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:a52d92e4-c560-4e33-add9-4ea2d382f9e1","http://resolver.tudelft.nl/uuid:a52d92e4-c560-4e33-add9-4ea2d382f9e1","Engine Power Effects on Support Interference","Horsten, B.J.C.; Veldhuis, L.L.M.","","2009","Renewed interest in propeller propulsion on aircraft configurations combined with higher propeller loads lead to the question how the effects of the propulsion on model support disturbances should be accounted for. In this paper, the determination of engine power effects on support interference of sting-mounted models is demonstrated by a measurement on a four-engine turboprop aircraft. CFD results on a more generic model are presented in order to clarify the possible mechanism behind engine power effects on support interference. The engine slipstream induces a local change in angle of sideslip at the model sting thereby influencing the sting near-field and far-field effects. Whether or not the net result of these changes in the disturbance pattern leads to a significant engine power effect depends on the configuration of the wind tunnel model and the test setup.","CFD; engine power effects; measurements; support interference","en","conference paper","World Academy of Science, Engineering and Technology","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:ef4ba8f8-be72-4811-b755-afb6b4c66e39","http://resolver.tudelft.nl/uuid:ef4ba8f8-be72-4811-b755-afb6b4c66e39","Optimization of RNAV Noise abatement arrival trajectories","Hogenhuis, R.H.; Hebly, S.J.; Visser, H.G.","","2008","","trajectory optimization; noise abatement; RNAV procedures","en","conference paper","Optimage Ltd.","","","","","","","","Aerospace Engineering","","","","",""
"uuid:fc4db167-f591-49cf-9474-d05577da5644","http://resolver.tudelft.nl/uuid:fc4db167-f591-49cf-9474-d05577da5644","Preliminary trajectory design for a solar polar observatory using SEP and multiple gravity assists","Corpaccioli, L.; Noomen, R.; De Smet, S.; Parker, J.S.; Herman, J.F.C.","","2015","Satellite solar observatories have always been of central importance to heliophysics; while there have been numerous such missions, the solar poles have been extremely under-observed. This paper proposes to use low-thrust as well as multiple gravity assists to reach the enormous energies required obtain high heliocentric inclinations. Two novel methods are used to provide initial guesses to a low-thrust trajectory optimizer. Results show that the complete trajectory would take between 3-4 years, although scientific observations can start already after 2 years. This assumes starting masses of 1000-2000 kg, and payload masses of 500-1300 kg. The best inclinations reached are 55-65 degrees to the ecliptic, while maintaining a perihelion and aphelion of 0.5 and 1 AU respectively. More research still needs to be performed to attempt to reach a global optimum. Further investigation is suggested to extend the mission for further objectives, such as lowering perihelion, or further cranking inclination.","solar observatory; multiple gravity assists; low-thrust; ecliptic inclination; Solar Electric Propulsion (SEP); trajectory optimization; GASP","en","conference paper","DLR","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:3af8309c-5feb-41f8-b693-d499eb68b717","http://resolver.tudelft.nl/uuid:3af8309c-5feb-41f8-b693-d499eb68b717","Development of a solar thermal thruster system","Leenders, H.C.M.; Zandbergen, B.T.C.","","2008","At the Delft University of Technology the use of solar radiation to heat a propellant to a high temperature is investigated as an alternative to resistance heating. The latter only allows for a solar power to heat conversion efficiency of about 25%, depending on the solar cells, whereas for solar heating 80% seems feasible. This paper addresses the theoretical and experimental investigations performed in the field of solar thermal propulsion at Delft University and more specific the solar thermal thruster development. The work performed includes the development of a theoretical model that assists the designer in the design and prediction of the performances of the solar thermal thruster. Also a demonstration solar thermal thruster has been developed and tested at different mass flow rates to verify the model. These tests have been performed using the Delft Aerospace Rocket Test Stand. Measurement parameters included thrust, propellant temperature, mass flow and pressure. In this paper we will present an overview of the theoretical model developed, the demonstration thruster as well as the test results. Finally, we present the main conclusions and recommendations related to the outcomes of the work.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:ff070ee1-460f-47ba-9528-b425cd93b9d0","http://resolver.tudelft.nl/uuid:ff070ee1-460f-47ba-9528-b425cd93b9d0","Probabilistic analysis of manufacturing uncertainties for an automotive turbocharger centrifugal compressor using numerical and experimental methods","Javed, A.; Kamphues, E.; Hartuc, T.; Pecnik, R.; Van Buijtenen, J.P.","","2015","The compressor impellers for mass-produced turbochargers are generally die-casted and machined to their final configuration. Manufacturing uncertainties are inherently introduced as stochastic dimensional deviations in the impeller geometry. These deviations eventually propagate into the compressor functionality as variability in output performance. This paper presents a probabilistic evaluation of the impact of manufacturing uncertainties on the compressor performance using the non-intrusive Monte Carlo method coupled with metamodels prepared for compressor performance modeling using computational fluid dynamics (CFD) and comprehensive experimentation. The probabilistic evaluation or the uncertainty quantification (UQ) of manufacturing uncertainties has identified the most sensitive and uncertain of the impeller geometric parameters contributing the most to variability in compressor performance. Consequently, the tolerances of different impeller dimensions can be reviewed, thereby influencing the production quality and costs.","","en","conference paper","European Conference on Turbomachinery","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:14e9fa43-cf40-4675-b641-84f90cb46bfd","http://resolver.tudelft.nl/uuid:14e9fa43-cf40-4675-b641-84f90cb46bfd","Does Systems Engineering in Space Projects Pay?","Hamann, R.J.; Zandbergen, B.T.C.; Zijdemans, P.J.","","2009","This paper attempts to answer the question whether it “pays” to apply Systems Engineering methods, tools and techniques within a space project. To this purpose a possible correlation has been investigated between the Systems Engineering effort applied within a number of space projects and the project result in terms of technical quality, cost and schedule. Use has been made of historical data derived from the results of Systems Engineering audits of projects, some recent audits performed along the same lines and assessments of project results in terms of technical quality, cost and schedule by the systems engineers involved in the projects. Basis for the audits is a checklist addressing 93 different aspects of Systems Engineering in the field of requirements, concept design, design & development, verification and technical management. In total nine data sets related to six projects in the industrial and the academic world were used. Although the data obtained are rather “noisy” there appears to be a clear positive correlation between the SE effort applied and the project result. It appears also that the positive effects mainly show up in the cost and schedule results of the project, the technical quality of the project result being generally of a rather satisfactory level. Examining the results in detail the Systems Engineering effort in the field of requirements, design & development and technical management has the strongest correlation with the project result. The effort in the field of (concept) design and verification shows a less strong correlation. The data have been “refined” by deleting the projects that were most strongly influencing the correlation in a positive sense. The overall results remained, however, the same. An overview is given of those aspects generally receiving little attention in the Systems Engineering effort. Further analysis of these results will be the subject of a follow-on study.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:28c9e346-f265-47e0-9605-ed4ba59e7f50","http://resolver.tudelft.nl/uuid:28c9e346-f265-47e0-9605-ed4ba59e7f50","Design and analysis of a multi-cell subscale tank for liquid hydrogen storage","Tapeinos, I.; Koussios, S.; Groves, R.M.","","2015","This paper outlines the structural performance of a conformable pressurizable tank consisting of intersecting spherical shells (multi-cell tank). Multi-cell tanks outrival conventional multiple cylindrical tanks in volumetric efficiency when required to fit in a rectangular envelope in the automotive industry. When pressurized, the multi-cell (or multi-bubble) tank experiences high stress concentrations at the vicinity of the junctions, and thus the concept of effectively reinforcing those regions without adding significant excess weight becomes crucial. Furthermore when applied for cryogenic medium storage the heat transfer between different bodies and generation of respective thermal stresses in such vessels makes the solution more complicated. In this paper the effect of the i) fiber-reinforced materials at the membrane and ii) unidimensional carbon tows at the intersections on the structural integrity of the tank is analyzed for different loading scenarios.","conformable tanks; thermal stresses; finite element method","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:4ebdcb07-05c1-426a-a1e2-eaa7f3c3a3f0","http://resolver.tudelft.nl/uuid:4ebdcb07-05c1-426a-a1e2-eaa7f3c3a3f0","Evaluating solvents as healing-agents in thermoplastic matrics via dynamic synchrotron x-ray microtomography (abstract)","Mookhoek, S.D.; Fischer, H.R.; Van der Zwaag, S.; Ludwig, W.","","2011","","self-healing; thermoplastics; x-ray tomography; synchrotron","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:6218bcec-86ae-4f00-bc6a-17f5d0459c58","http://resolver.tudelft.nl/uuid:6218bcec-86ae-4f00-bc6a-17f5d0459c58","Efficient use of the Noise Budget at Schiphol Airport through Minimax Optimization of Runway Allocations","Kuiper, B.R.; Visser, H.G.; Heblij, S.","","2011","This paper presents the development of a runway allocation planning tool that seeks to maximize the permissible number of flight operations into and out of an airport within a given annual noise budget. Although the model that underlies the planning tool is generic in nature, the tool has been customized for application to a specific airport, viz. Amsterdam airport Schiphol in the Netherlands. The noise budget regulations applicable at Schiphol stipulate limits on the annual cumulative noise loads at a large number of enforcement points arranged around the airport. To ensure an equitable distribution of the cumulative noise load at the enforcement points, an efficient allocation and distribution of the annual flight movements over available runways and routes is required that takes weather induced restrictions into account. To this end, a Linear Programming (LP) optimization formulation has been developed that implements a minimax performance criterion that aims to minimize the maximum cumulative noise load value occurring at any of the enforcement points. The numerical results obtained for the operational year 2005 clearly demonstrate the potential of the tool to maximize the yearly number of flight movements within the assigned noise budget.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:efd5d40c-3062-4d98-9f71-bbc431b9cd65","http://resolver.tudelft.nl/uuid:efd5d40c-3062-4d98-9f71-bbc431b9cd65","Tree filtering for high density airborne LiDAR data","Abd Rahman, M.Z.; Gorte, B.G.H.","","2008","A high resolution Airborne LiDAR data creates better opportunity for an individual tree measurement and provides valuable results for more precise forest inventory. This paper presents tree filtering approach that able to separate dominant tree and undergrowth vegetation. The results can be used for a detailed individual tree measurement. This process is one of the main steps for a single tree extraction from the high resolution Airborne LiDAR data. The filtering technique lies on the fact that a dominant tree has distinct parts in the histogram that represent tree crown, tree trunk, and ground surface with or without undergrowth vegetation. The shape of the histogram was used to identify points that belong to the tree crown and the tree trunk. More points were assigned to the tree trunk based on an iterative analysis of the histogram at certain height above the ground surface. This step was coupled with the RG segmentation. It was found that the filtering routine failed to remove very close undergrowth vegetation. It was also observed that in order to get a good result, the tree filtering method needs at least small area of the tree trunk.","high resolution Airborne LiDAR; RG segmentation; 1D Gaussian filter; Gaussian fitting","en","conference paper","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:0505773e-a61f-4221-8603-46cd521ff8ea","http://resolver.tudelft.nl/uuid:0505773e-a61f-4221-8603-46cd521ff8ea","Crystalline damage development during martensitic transformations","Suiker, A.S.J.; Turteltaub, S.R.","","2006","A recently developed thermo-mechanical model [1] is presented that can be used to simulate the interactions between martensitic phase transformations and crystalline damage growth at the austenitic grain level. Subgrain information is included in the model via the crystallographic theory of martensitic transformations, see also [2,3]. The state of transformation for the individual transformation systems is represented by the corresponding volume fractions. The state of damage in the austenite and the martensitic transformation systems is reflected by the corresponding damaged volume fractions. The thermodynamical forces energetically conjugated to the rate of volume fraction and the rate of damaged volume fraction are the driving forces for transformation and crystalline damage, respectively. The model is used to analyse three-dimensional boundary value problems that are representative of microstructures appearing in multiphase carbon steels assisted by transformation-induced plasticity. The numerical integration of the model is performed within a finite deformation framework, using a fully implicit Euler backward method. The consistent tangent is computed numerically by consistent linearization of the updated stress, see also [4]. The analyses show that the growth of damage effectively limits the elastic stresses developing in the martensitic product phase, where the maximum value of the stress strongly depends on the toughness of the martensite. Furthermore, the generation of crystalline damage delays the phase transformation process, and may arrest it if the martensitic product phase is sufficiently brittle. The response characteristics computed with the phase-changing damage model are confirmed by experimental results.","martensite; austenite; crystalline damage; TRIP steels; shape-memory alloys","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4bbe1615-6670-4f78-b142-c44dfeb8d78f","http://resolver.tudelft.nl/uuid:4bbe1615-6670-4f78-b142-c44dfeb8d78f","Acceleration of Strongly Coupled Fluid-Structure Interaction with Manifold Mapping","Blom, D.S.; Van Zuylen, A.H.; Bijl, H.","","2014","Strongly coupled partitioned fluid-structure interaction problems require multiple coupling iterations per time step. The fluid domain and the structure domain are solved multiple times in each time step such that the kinematic and dynamic interface conditions on the fluid-structure interface are satisfied. Quasi-Newton methods have been successfully applied in case the fluid and structure solvers are considered as black boxes, i.e. only input and output information of the solvers are used by the coupling techniques. In this contribution a computationally inexpensive low-fidelity model is combined with a high-fidelity model in order to accelerate the convergence of the high-fidelity model. This is achieved by applying the manifold mapping algorithm on the fluid-structure interaction problem in order to minimize the fluid-structure interface residual. Originating from multi-fidelity optimization, the manifold mapping algorithm is applied for the first time in a simulation context, instead of an optimization context. The manifold mapping algorithm is applied on a standard fluid-structure interaction benchmark, namely the cylinder flap FSI3 case. A reduction of 48% in terms of high fidelity iterations is achieved compared with the inverse least squares Quasi-Newton algorithm, resulting in a 42% decrease in computational costs.","fluid-structure interaction; manifold mapping; partitioned; strong coupling","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:1cd8f54f-596f-44e8-9fad-42da7c6efbda","http://resolver.tudelft.nl/uuid:1cd8f54f-596f-44e8-9fad-42da7c6efbda","The KNOMAD Methodology for Integration of Multi-Disciplinary Engineering Knowledge within Aerospace Production","Curran, R.; Verhagen, W.J.C.; Van Tooren, M.J.L.","","2010","The paper is associated with the integration of multi-disciplinary knowledge within a Knowledge Based Engineering (KBE)-enabled design framework. To support this integration effort, the KNOMAD methodology has been devised. KNOMAD stands for Knowledge Optimized Manufacture And Design and is a methodology for the analytical utilisation of multi-disciplinary engineering knowledge within design. The KNOMAD acronym can also be used to highlight KNOMAD’s formalized process of: (K)nowledge capture; (N)ormalisation; (O)rganizations; (M)odelling; (A)nalysis; and (D)elivery. The main contribution of the paper is to highlight the development of the KNOMAD methodology and to substantiate its individual steps with sufficient detail to support the application of KNOMAD in practice.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:1abbc5f1-499d-4759-bb8d-d351d301e560","http://resolver.tudelft.nl/uuid:1abbc5f1-499d-4759-bb8d-d351d301e560","Large-eddy simulation of cavitating nozzle and jet flows","Örley, F.; Trummler, T.; Hickel, S.; Mihatsch, M.S.; Schmidt, S.J.; Adams, N.A.","","2015","We present implicit large-eddy simulations (LES) to study the primary breakup of cavitating liquid jets. The considered configuration, which consists of a rectangular nozzle geometry, adopts the setup of a reference experiment for validation. The setup is a generic reproduction of a scaled-up automotive fuel injector. Modelling of all components (i.e. gas, liquid, and vapor) is based on a barotropic two-fluid two-phase model and employs a homogenous mixture approach. The cavitating liquid model assumes thermodynamic- equilibrium. Compressibility of all phases is considered in order to capture pressure wave dynamics of collapse events. Since development of cavitation significantly affects jet break-up characteristics, we study three different operating points. We identify three main mechanisms which induce primary jet break-up: amplification of turbulent fluctuations, gas entrainment, and collapse events near the liquid-gas interface.","","en","conference paper","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:513b9f39-6129-4a26-820c-883f162d0d22","http://resolver.tudelft.nl/uuid:513b9f39-6129-4a26-820c-883f162d0d22","Use of simulator motion feedback for different classes of vehicle dynamics in manual control tasks","Lu, T.; Pool, D.M.; Van Paassen, M.M.; Mulder, M.","","2015","With the development of moving-based flight simulators in mind, a large number of researchers have considered human manual control behavior in tasks where the motion of the controlled vehicle can be felt by the pilots. While it is known that the dynamics of the controlled vehicle are a key factor that determines the usefulness of motion feedback, there is no systematic study of the use of motion feedback over a wide range of controlled dynamics. Therefore, this paper describes a human-in-the-loop yaw attitude compensatory tracking experiment that was conducted to evaluate the effects of motion feedback on task performance, as well as the open-loop crossover frequency and phase margin. A gain, a single integrator and a double integrator were selected as the different controlled elements in this experiment, respectively. For the double integrator controlled element, the results confirms the findings of previous studies that the motion feedback is crucial in improving task performance and increasing the open-loop phase margin for enhanced stability. However, for both the gain and single integrator controlled elements, the motion feedback is not helpful in the aspect of changing task performance, target crossover frequency and phase margin.","","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:ad66281b-92aa-4ea2-82a7-880f31f51d80","http://resolver.tudelft.nl/uuid:ad66281b-92aa-4ea2-82a7-880f31f51d80","The new airport of Lisbon: A strategic framework","Correira, V.M.; Houlleberghs, B.R.Y.","","2008","","","en","conference paper","TRAIL Research School","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ff363ac4-4b95-427a-af2c-89c79de30d88","http://resolver.tudelft.nl/uuid:ff363ac4-4b95-427a-af2c-89c79de30d88","Air traffic controller decision-making consistency and consensus in conflict solution performance","Westin, C.; Hilburn, B.; Borst, C.","","2015","Consistency and consensus in conflict solution performance was investigated in two real-time simulations involving experienced air traffic controllers and trainees. The simulations consisted of participants repeatedly playing a specific en route traffic scenario. Conflict solution performance and consistency was measured by analysing participant’s solutions to a specifically designed conflict. Consensus was determined by comparing participant’s consistent conflict solution behaviour. Four different clusters of consistent behaviour were identified. All participants could be classified as consistent according to one or more of these clusters. Consensus in solving the designed conflict could not be determined between participants. There were, however, smaller groups of participants who solved the designed conflict similarly. Participants varied considerably in terms if when to interact and solve the conflict. This is a potential issue when it comes to determining thresholds for the timing of decision-aid interaction.","","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:a1f9b330-503d-4892-8657-3dc4b3bb5a91","http://resolver.tudelft.nl/uuid:a1f9b330-503d-4892-8657-3dc4b3bb5a91","Determination of instantaneous pressure in an axisymmetric base flow using time-resolved tomographic PIV","Blinde, P.L.; Gentile, V.; Van Oudheusden, B.W.; Schrijer, F.F.J.","","2015","Quantification of mean and fluctuating surface loads is critical for the efficient design of aerospace structures. To measure surface pressure in experiments, wind tunnel models are typically equipped with pressure transducers, which offer high sampling rates and high sensitivity. In order to have a sufficient spatial sampling of the surface pressure such that the instantaneous surface loads can be determined, a large number of transducers is required. From a practical point of view, the installation of transducers can be costly and can pose significant challenges due to spatial limitations inside the wind tunnel model. An alternative for measuring pressure is PIV-based pressure determination [1]. In this approach, PIV data are used to determine the material acceleration, which is related to the local pressure gradient via the momentum equation. Whereas the mean pressure field can be obtained from a series of uncorrelated velocity fields (e.g. [2]), the availability of time-resolved PIV data allow for the determination of instantaneous pressure fields. Recent developments in PIV measurement capabilities, in particular tomographic PIV [3], have made this technique increasingly feasible and appealing. A particular advantage of the technique is that it provides simultaneous velocity and pressure data in the full flow field, thus enabling a better understanding of the relation between fluid dynamics and the corresponding pressure field. The ability of PIV to determine the material acceleration, from which the pressure can subsequently be obtained, has been the subject of extensive study. Using two or more velocity fields closely separated in time, the material acceleration can be determined using traditional Eulerian or Lagrangian formulations (see e.g. [1] for details). An improved estimate of the material acceleration may be obtained using fluid trajectory tracking (FTC) which correlates more than two consecutive reconstructions [4, 5]. The present study builds on these efforts by using time-resolved tomographic PIV to obtain instantaneous pressure distributions in a low-speed axisymmetric base flow. Results are compared to simultaneous unsteady pressure measurements using microphones and mean pressure measurements using static pressure sensors.","","en","conference paper","University of Poitiers","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:32033ec6-faad-487a-959c-886d97d106f2","http://resolver.tudelft.nl/uuid:32033ec6-faad-487a-959c-886d97d106f2","Modeling the effect of night time penalties on commercial and business flights for regional airport noise and economics: Rotterdam Airport case study","Wan Mohamed, W.M.; Curran, R.; Van der Zwan, F.M.; Roling, P.","","2009","Noise is one of the main concerns of airports around the world. Several measures have been taken by regulators to reduce noise at airports. Some of these measures are meant to control noise at major or busy airports; however, certain operational restrictions (quota, curfew, and budget) are also implemented throughout the whole country regardless of the role and the size of the airports. An empirical example, using the Rotterdam Airport, a regional airport in the Netherlands, illustrates how regional airport should determine its night surcharges policies, especially with different type of aircraft categories. In this research, the night surcharges received from Business Jet category and Commercial aircraft category are being compared. The results indicate that the night surcharges did not compensate for the number of day time flight movements and potential revenues losses. Regional airport may need to be more selective in setting the night surcharges in order to maximise its revenues.","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:506b1f29-bc38-4c53-a995-bcbe9d859d60","http://resolver.tudelft.nl/uuid:506b1f29-bc38-4c53-a995-bcbe9d859d60","Effects of Displayed Error Scaling in Compensatory Roll-Axis Tracking Tasks","Breur, S.W.; Pool, D.M.; Van Paassen, M.M.; Mulder, M.","","2010","This paper describes an investigation into the effects of displayed error scaling on manual control behavior during compensatory roll-axis tracking. Previous experiments have indicated that for compensatory displays that, similar to an artificial horizon, present the roll tracking errors in rotational form, the deviations for typical quasi-random forcing function signals are comparatively small and difficult to perceive. This was found to lead to degraded tracking performance and lower crossover frequencies than would be expected. To investigate this, a roll-axis tracking experiment has been performed in which the scaling of the presented tracking errors was varied from 0.5 to 5 times the true tracking error. In addition, both double integrator dynamics and typical conventional roll dynamics of a small jet aircraft were considered in a mixed experimental design. The main hypothesis for this experiment was that increased scaling of the presented roll-axis tracking error would result in improved tracking performance and correlation of manual control inputs with the target forcing function signal. In addition, these effects were hypothesized to be more pronounced for the more difficult double integrator dynamics. For both controlled elements, both tracking performance and linearity of pilot control were indeed found to increase with increasing display gain, leveling of for the highest considered display gains. Further analysis of manual control behavior using McRuer et al.’s Precision Model revealed marked changes in the adopted control strategy due to changes in displayed error scaling, which were found to be highly similar for both controlled elements.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:dafb5d2a-87e5-4317-8d03-21821c75b758","http://resolver.tudelft.nl/uuid:dafb5d2a-87e5-4317-8d03-21821c75b758","Advancing nano-satellite platforms: The Delfi Program","Bouwmeester, J.; Gill, E.K.A.; Verhoeven, C.J.M.","","2008","The Delfi Program aims to launch a nano-satellite every 2.5 years with the objectives to give the best education for space engineering, to test and qualify novel space technology and to enhance the nanosatellite platform to open doors for new applications. With Delfi-C3 in orbit, Delfi-n3Xt in development for a launch in 2010 and preliminary plans for the future, TU Delft wants to put itself at the top level of small satellites engineering. Although the size of nano-satellites puts some constraints on the potential performance and applications, the theoretical limits are still far ahead and nano-satellites might have more potential than typically assumed. This potential can only be made possible if the development goal for each satellite matches the availability of resources and a realistic planning in time.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:00730203-1f6b-4881-b6d7-e0aca6b4f545","http://resolver.tudelft.nl/uuid:00730203-1f6b-4881-b6d7-e0aca6b4f545","Ship propulsion by Kites combining energy production by Laddermill principle and direct kite propulsion","Lansdorp, B.; Ockels, W.J.; Ruiterkamp, R.","","2006","","laddermill; wind energy","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5961ef81-14be-4c49-8e80-81ea3ebb6a54","http://resolver.tudelft.nl/uuid:5961ef81-14be-4c49-8e80-81ea3ebb6a54","Energy function behavior in optimization based image sequence stabilization in presence of moving objects","Karimi Nejadasl, F.; Gorte, B.G.H.; Snellen, M.M.; Hoogendoorn, S.P.","","2008","In this paper, we address the registration of two images as an optimization problem within indicated bounds. Our contribution is to identify such situations where the optimum value represents the real transformation parameters between the two images. Consider for example Mean Square Error (MSE) as the energy function: Ideally, a minimum in MSE corresponds to transformation parameters that represent the real transformation between two images. In this paper we demonstrate in which situations the optimum value represents the real transformation parameters between the two images. To quantify the amount of disturbances allowed, these disturbances are simulated for two separate cases: moving objects and illumination variation. The results of the simulation demonstrate the robustness of stabilizing image sequences by means of MSE optimization. Indeed, it is shown that even a large amount of disturbances will not cause the optimization method to fail to find the real solution. Fortunately, the maximal amount of disturbances allowed is larger than the amount of signal disturbances that is typically met in practice.","registration; transformation; visualization; orientation; correlation; image sequences; aerial","en","conference paper","International Society for Photogrammetry and Remote Sensing","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:83942599-06d5-4a35-ac29-a85b676d4838","http://resolver.tudelft.nl/uuid:83942599-06d5-4a35-ac29-a85b676d4838","International Design Synthesis Exercise 2006: Design of an Interceptor UAV","Roling, P.C.; Cooper, R.; Curran, R.","","2008","","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8d114164-ed06-477e-9c1d-1284f668c00f","http://resolver.tudelft.nl/uuid:8d114164-ed06-477e-9c1d-1284f668c00f","An Automated Design Approach for High-Lift Systems incorporating Eccentric Beam Actuators","Steenhuizen, D.; Van Tooren, M.J.L.","","2010","In order to asess the merit of novel high-lift structural concepts to the design of contemporary and future transport aircraft, a highly automated design routine is elaborated. The structure, purpose and evolution of this design routine is set-out with the use of Knowledge-Based Engineering techniques. As a case-study, the automated design of the Eccentric Beam Actuator is treated here, but the developed routine is meant to be applicable in a generic fashion, allowing for other concepts in the future.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:c6fe7964-ce90-48c2-8575-cc6f6e77ec3e","http://resolver.tudelft.nl/uuid:c6fe7964-ce90-48c2-8575-cc6f6e77ec3e","An extension of dynamic droplet deformation models to secondary atomization","Bartz, F.O.; Schmehl, R.; Koch, R.; Bauer, H.J.","","2010","A detailed model for secondary atomization of liquid droplets by aerodynamic forces is presented. As an empirical extension of dynamic droplet deformation models, it accounts for temporal variations of the relative velocity between droplet and gas phase during the deformation and breakup process and describes the characteristic features of different breakup mechanisms (deformation kinetics, aerodynamics and product properties). Computed droplet trajectories and Sauter mean diameters have been compared using the proposed deformation-based model and a model using a breakup criterion based on the local instantaneous Weber number. It is concluded, that a deformation-based criterion should be used for droplets exposed to complex aerodynamic loading and that more experimental research is required to identify the accuracy of the presented detailed breakup product model.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:43816887-0dfa-4a8e-80dc-40ce5596e07e","http://resolver.tudelft.nl/uuid:43816887-0dfa-4a8e-80dc-40ce5596e07e","Nonlinear and fault-tolerant flight control using multivariate splines","Tol, H.J.; De Visser, C.C.; Van Kampen, E.J.; Chu, Q.P.","","2015","This paper presents a study on fault tolerant flight control of a high performance aircraft using multivariate splines. The controller is implemented by making use of spline model based adaptive nonlinear dynamic inversion (NDI). This method, indicated as SANDI, combines NDI control with nonlinear control allocation based on an onboard aerodynamic spline model and a real-time identification routine. The controller is tested for an aileron hardover failure and structural damages which change the global aerodynamic properties of the aircraft. It is shown that the controller can quickly tune itself in failure conditions without the need of failure detection and monitoring algorithms. Instead, self-tuning innovation based forgetting is applied to reconfigure the onboard aerodynamicmodel. The controller is able to tune itself each time a model error is detected and does not require any external triggers for re-identification. Multivariate splines have a high local approximation power and are able to accuratelymodel nonlinear aerodynamics over the entire flight envelope of an aircraft. As a result the identification routine gives a robust adaption of the aerodynamic model in case of a failure.","","en","conference paper","","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:b31b4a47-ad62-499d-8cca-32db128141a3","http://resolver.tudelft.nl/uuid:b31b4a47-ad62-499d-8cca-32db128141a3","A VLBI view on the extreme scintillator J1819+3845","Cimo, G.; Gurvits, L.; Kharb, P.; De Bruyn, G.; Macquart, J.P.","","2012","Scintillation of flat spectrum radio sources provides a unique instrument to study the characteristics of the electron density distribution throughout the interstellar medium as well as to study the microarcsecond structure of compact radio objects. During the course of its extreme activity, the quasar J1819+3845 has been observed with a number of VLBI arrays. The fast variability, up to 600% in less than one hour, has made it very difficult to image the source. The variability has now stopped and we will present scintillation-free VLBI images of J1819+3548 taken with the EVN (2008) and VLBA (2007). We will compare the quiescent phase of J1819+3845 with images of the source during its extreme variability (observed with global and space VLBI). A description of the possible scattering screen and implications for the source internal structure will be presented.","","en","conference paper","POS","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:8a72877d-bf6c-491c-9ea6-5824d96a890a","http://resolver.tudelft.nl/uuid:8a72877d-bf6c-491c-9ea6-5824d96a890a","Roughness Induced Boundary Layer Transition in Incompressible Flow","Ye, Q.; Schrijer, F.J.; Scarano, F.","","2015","The fluid dynamics process leading to laminar-turbulent transition behind an isolated roughness element is investigated in the incompressible regime using particle image velocimetry. The study covers the effect of roughness size and geometry on the promotion of transition. The measurement domain covers a large streamwise range from the near wake to the onset of the turbulent regime. Planar PIV measurements reveal the basic flow pattern and the turbulent structure of the flow characterizing by the velocity fluctuation statistics (RMS of the streamwise and wall-normal velocity component and Reynolds shear stress). The high Reynolds shear stress level reaching the region near the wall in the downstream area indicates the onset of turbulent boundary layer.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:8798df85-fefb-48b7-8c13-ac25dd58b765","http://resolver.tudelft.nl/uuid:8798df85-fefb-48b7-8c13-ac25dd58b765","Reducing the error in terrestrial laser scanning by optimizing the measurement set-up","Soudarissanane, S.S.; Lindenbergh, R.C.; Gorte, B.G.H.","","2008","High spatial resolution and fast capturing possibilities make 3D terrestrial laser scanners widely used in engineering applications and cultural heritage recording. Phase based laser scanners can measure distances to object surfaces with a precision in the order of a few millimeters at ranges between 1 and 80 m. However, the quality of a laser scanner end-product, like a 3D model, is influenced by many different parameters, especially the relative object surface orientation and the local point cloud density. This paper introduces the notion of point cloud quality. The obtained point cloud is first segmented using a planar feature extraction segmentation. Each segment is subdivided into smaller patches of 20 × 20 cm. For each patch a patch quality parameter is determined, which incorporates the local point density and local point quality. By averaging the patch quality over the complete point cloud, a point cloud quality is derived. This paper demonstrates this approach in practice by comparing two scans of the same test room obtained from different stand-points. As a result, it is shown and analyzed that by simply moving the scanner by two meters, the quality of the point cloud can be improved by 25 %.","laser scanning; point cloud; error; noise level; accuracy; optimal stand-point","en","conference paper","International Society for Photogrammetry and Remote Sensing","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:86744b74-41fe-41ff-8931-16045be1680c","http://resolver.tudelft.nl/uuid:86744b74-41fe-41ff-8931-16045be1680c","Airfoil drag elimination and stall suppression via piezoelectric dynamic tangential synthetic jet actuators","Barrett, R.; Corpening, J.; Reasonover, C.","","2005","This paper describes a new method for drag elimination and stall suppression via tangential synthetic jet actuators. This boundary layer control (BLC) method is shown to perform as well as continuous and normal synthetic jet BLC methods but without fouling difficulties, system-level complexity or extreme sensitivity to Reynolds number. Classical laminated plate theory (CLPT) models of the piezoelectric actuators were used to estimate diaphragm deflections and volume per stroke. A 12” (30.5cm) chord, 6” (15.3cm) span NACA 0012 profile wing section was designed with three unimorph 10 mil (254µm) thick, 3.25” (8.23cm) square piezoelectric diaphragm plenums and five 1 mil (25µm) thick stainless steel valves spaced from 15%c to the trailing edge of the airfoil. Static bench testing showed good correlation between CLPT and experiment. Plenum volume per stroke ranged up to 5cc at 500 V/mm field strength. Dynamic testing showed resonance peaks near 270 Hz, leading to flux rates of more than 60 cu in/s (1 l/s) through the dynamic valves. Wind tunnel testing was conducted at speeds up through 13.1 ft/s (4 m/s) showing more than doubling of Clmax. At low angles of attack and high flux rates, the airfoil produced net thrust for less than 4.1W of electrical power consumption.","piezoelectric; synthetic jet; stall suppression; drag reduction; boundary layer control","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5be21cb0-bc19-4b56-8cbe-518dcfc120aa","http://resolver.tudelft.nl/uuid:5be21cb0-bc19-4b56-8cbe-518dcfc120aa","Experimental and numerical investigation of the flow-induced resonance of slender deep cavities that resemble automotive door gaps","De Jong, A.T.; Bijl, H.","","2010","Cavity aeroacoustic noise is relevant for aerospace and automotive industries and widely investigated since the 1950’s. Most investigations so far consider cavities where opening length and width are of similar scale. The present investigation focuses on a less investigated setup, namely cavities that resemble the door gaps of automobiles. These cavities are both slender (width much greater than length or depth) and partially covered. Furthermore they are under influence of a low Mach number flow with a relatively thick boundary layer. Under certain conditions, these gaps can resonate with the flow. The present investigation attempts to reveal the aeroacoustic mechanism of this tonal noise. Also the ability to simulate the resonance behavior using the Lattice Boltzmann method (LBM) is evaluated. Experiments have been conducted on simplified geometries, where hotwire, high speed PIV and microphone measurements have been used. The opening geometry and boundary layer properties have been varied. Using the PIV results, the observed influences of the opening geometry on base mode resonance are explained. With increasing velocity, several resonance modes occur. In order to obtain higher mode shapes, the cavity acoustic response is simulated using LBM and compared with experiment. Using the frequency-filtered simulation pressure field, the higher modes shapes are retrieved. Based on this an analytical model is derived that shows good agreement with the simulations and experimental results. LBM based flow simulations show that the turbulent fluctuation content of the boundary layer is important to correctly simulate the flow induced resonance response. When unsteady fluctuations are implemented in the inlet of the simulation, the cavity excitation shows good resemblance with experiment.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:2daec500-3379-46a7-a747-90baf6044f58","http://resolver.tudelft.nl/uuid:2daec500-3379-46a7-a747-90baf6044f58","Towards Flight Testing of Remotely Controlled Surfkites for Wind Energy Generation","Lansdorp, B.; Ruiterkamp, R.; Ockels, W.","","2007","Non-powered flight vehicles such as kites can provide a means of transmitting wind energy from higher altitudes to the ground via tethers. Although there is increased world wide interest for systems to extract wind energy from higher altitudes with kites, research into kite properties such as the coefficients and the stability is limited. Such research is required to increase the knowledge on kites, which would enable the design of purpose-built kites for energy extraction. This paper presents one of the concepts for wind energy extraction from high altitudes; the Laddermill. Furthermore it presents the hardware that was built to do such tests, test procedures for kites and early results of testing of commercially available surf kites.","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:733e4dbf-18c0-4084-84c3-47ef54259002","http://resolver.tudelft.nl/uuid:733e4dbf-18c0-4084-84c3-47ef54259002","PIV visualization of dynamic stall VAWT and blade load determination","Simao Ferreira, C.J.; Van Bussel, G.J.W.; Scarano, F.; Van Kuik, G.A.M.","","2008","","","en","conference paper","American Institute of Aeronautics and Astronautics AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d79b7832-4bf8-44f2-a741-165f7c5bdb01","http://resolver.tudelft.nl/uuid:d79b7832-4bf8-44f2-a741-165f7c5bdb01","The ARISTOTEL project: Aircraft and Rotorcraft Pilot Couplings – Tools and Techniques for Alleviation and Detection","Pavel, M.D.","","2011","","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4095d737-9316-49d0-a949-e28d597fe9f1","http://resolver.tudelft.nl/uuid:4095d737-9316-49d0-a949-e28d597fe9f1","Optical coherence tomography complemented by hyperspectral imaging for the study of protective wood coatings","Dingemans, L.M.; Papadakis, V.; Liu, P.; Adam, A.J.L.; Groves, R.M.","","2015","Optical coherence tomography (OCT) is a contactless and non-destructive testing (NDT) technique based on lowcoherence interferometry. It has recently become a popular NDT-tool for evaluating cultural heritage. In this study, protective coatings on wood and their penetration into the wood structure were measured with a customized infrared fiber optic OCT instrument. In order to enhance the understanding of the OCT measurements of coatings on real wooden samples, an optimization of the measuring and analyzing methodology was performed by developing an averaging approach and by post-processing the data. The collected information was complemented by data obtained with hyperspectral imaging to allow data from local OCT A-scans to be used in mapping the coating thicknesses over larger areas.","optical coherence tomography; on-destructive testing; hyperspectral imaging; wood coatings; averaging; optimization; thickness mapping","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:30ed9583-d51a-480d-a6d5-2fe34600ef5e","http://resolver.tudelft.nl/uuid:30ed9583-d51a-480d-a6d5-2fe34600ef5e","Performance and stability of inflatable tube kites: For the application of a pumping airborne wind energy generator","Van der Vlugt, R.","","2011","The performance of a kite power system depends for a large part on the performance of the kite. In a pumping system the glide ratio, the maximum allowable wing loading and the ability to power and depower can significantly affect the average input power to the generator. This poster gives an overview of research activities and results in the field of kites at the TU Delft institute ASSET.","","en","conference paper","KU Leuven, OPTEC","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1a897b39-9461-40b3-b385-7b1777a1f9f4","http://resolver.tudelft.nl/uuid:1a897b39-9461-40b3-b385-7b1777a1f9f4","An investigation on the strain distribution of resistance welded thermoplastic composite joints","Shi, H.; Fernandez-Villegas, I.; Bersee, H.E.N.","","2012","In order to better understand the usefulness of single lap shear testing for the characterization of resistance welded thermoplastic composite joints, finite element method (FEM) and digital image correlation measurements (DIC) were combined to investigate the strain distributions of the joints during testing. Glass fibre reinforced Polyphenylene Sulfide (GF/PPS) was resistance welded in aid of a metal mesh. Shear and peel strain distributions were investigated at the joint overlap area. The effect of the resin fillet and metal mesh on the strain distributions and apparent shear strengths was investigated. A comparison between resistance welded and adhesively bonded GF/PPS joints was performed.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:fd2e40ee-6a5b-405c-9e56-81879b3dff57","http://resolver.tudelft.nl/uuid:fd2e40ee-6a5b-405c-9e56-81879b3dff57","An experimental study of reconstruction accuracy using a 12-Camera Tomo-PIV system","Lynch, K.; Scarano, F.","","2013","A tomographic PIV system composed of a large number of cameras is used to experimentally investigate the relation between image particle density, number of cameras and the reconstruction quality. The large number of cameras allows to determine an asymptotic behavior for the object reconstruction over a wide range of values for the tracer particles concentration. In order to quantify the effect of additional cameras, the quality of the reconstruction is evaluated through the reconstruction signal-to-noise ratio and the normalized intensity variance. The use of additional cameras even with small relative angular separation is shown to reduce the formation of ghost particles in the reconstructed volumes, resulting in a greater reconstruction signal-to-noise ratio and variance of the reconstructed object intensity. Object reconstructions are obtained for levels of the seeding density almost three times greater than a typical four-camera tomographic PIV system, based on evaluation of the reconstruction signal to noise ratio. This approach offers the perspective for future tomographic PIV measurements of higher resolution, particularly suited for the study of high-Reynolds number turbulent flows.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:dcbe8d84-fa07-4c0d-a696-50f0cba26eee","http://resolver.tudelft.nl/uuid:dcbe8d84-fa07-4c0d-a696-50f0cba26eee","Comparing Multimodal Pilot Pitch Control Behavior Between Simulated and Real Flight","Zaal, P.M.T.; Pool, D.M.","","2011","In order to improve the tuning process of flight simulator motion cueing filters and support the development of objective simulator motion cueing requirements, a better understanding of how multimodal pilot control behavior is affected by simulator motion fidelity is required. To this end, an experiment was performed where seven pilots performed a pitch target-following disturbance-rejection task in a simulator under four different motion cueing settings, in addition to performing the task in a real aircraft, which served as the baseline condition. Differences between the simulator and aircraft experiment setup were minimized. Small remaining differences in the display and the sidestick setup slightly affected the experiment dependent measures. However, the effects introduced by the motion cueing settings were far more apparent. When motion fidelity was increased to full aircraft motion, pilots were able to increase performance in attenuating the disturbance signal significantly. In addition, for increased motion fidelity, a change in multimodal pilot control behavior was observed by a decrease in pilot visual lead, while visual and vestibular perception delays increased. Pilot performance and control behavior in the simulator condition with full pitch motion and filtered pitch and c.g. heave motion was most similar to the in-flight condition.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:cb241978-8e1d-4689-8939-ded280041969","http://resolver.tudelft.nl/uuid:cb241978-8e1d-4689-8939-ded280041969","Design of a Lean MRO Business Process for EPCOR","Beelaerts van Blokland, W.W.A.; De Waard, A.; Curran, R.","","2008","","","en","conference paper","American Institute of Aeronautics and Astronautics, AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c614aecb-a8b9-48d8-bf6c-371c28a4f8c9","http://resolver.tudelft.nl/uuid:c614aecb-a8b9-48d8-bf6c-371c28a4f8c9","A multi-model incremental adaptive strategy to accelerate partitioned fluid-structure algorithms using space-mapping","Scholcz, T.P.; Van Zuijlen, A.H.; Bijl, H.","","2011","High fidelity analysis of fluid-structure interaction systems is often too timeconsuming when a large number of model evaluations are required. The choice for a solution procedure depends often on the efficiency of the method and the possibility of reusing existing field solvers. Aggressive Space-Mapping, a technique originally developed for multi-fidelity optimization, is applied to accelerate the partitioned solution procedure of a high fidelity fluid-structure interaction model. The method supports software modularity. Aggressive Space-Mapping (ASM) is applied to an academic testcase and the results are compared with the corresponding Incremental Quasi-Newton (IQN) method. An efficiency metric is defined to facilitate the comparison. The ASM method is found to be more efficient than the corresponding IQN method for the testcases considered. The efficiency of space-mapping increases with increasing fluid-to-structure mass ratio, indicating that the method is especially useful for strongly coupled problems.","fluid-structure interaction; partitioned coupling; space-mapping; multifidelity models; reduced order models","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:a0fda9a7-931f-44cb-8726-4e1feb7d730b","http://resolver.tudelft.nl/uuid:a0fda9a7-931f-44cb-8726-4e1feb7d730b","Accurate and efficient computation of steady water flow with surface waves and turbulence","Wackers, J.; Koren, B.","","2006","A surface capturing method is developed for steady water-air flow with gravity. Second-order accuracy is obtained with flux limiting and turbulence is modeled with Menter's model. The model is solved efficiently with a combination of multigrid and defect correction. Results for two test cases confirm the efficiency and accuracy of the method.","steady water waves; surface capturing; RANS; menter model; multigrid; defect correction","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:fc55594a-cb4e-4ddf-8a63-4b63146bccdb","http://resolver.tudelft.nl/uuid:fc55594a-cb4e-4ddf-8a63-4b63146bccdb","Automatic object recognition and change detection of urban trees","Van der Sande, C.J.","","2010","Monitoring of tree objects is relevant in many current policy issues and relate to the quality of the public space, municipal urban green management, management fees for green areas or Kyoto protocol reporting and all have one thing in common: the need for an up to date tree database. This study, part of the Tree and Image research project, developed a database-driven approach for object recognition and change detection using optical imagery including contextual data from urban tree databases and topographic data. Trees are 3D objects and vary in shape throughout the season. The tree is modelled in a 2D aerial image using the point location and species information. The tree model consists of a projected crown and shadow. These projections, polygons, are used to recognise the object with NDVI and texture parameters related to the ground surface derived from the topographic map and its neighbouring segments. This resulted in classifications of trees ‘still present’ or ‘disappeared’ with an overall accuracy of 85%. However, the errors of commission and omission were quite high due to the use of an early image with no full-grown crowns, resulting in difficult recognisable trees. Detected changes can be used for further human verification or directly serve as input for database management and decision making.","remote sensing; change detection; updating; segmentation; 3D; object oriented; urban; trees; database","en","conference paper","International Society of Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:4c0b91d1-8fb5-448e-bf55-0b027004168a","http://resolver.tudelft.nl/uuid:4c0b91d1-8fb5-448e-bf55-0b027004168a","Development of engineering services to support wingbox feasilisation within a multi-agent task environment","Berends, J.P.T.J.; Schut, E.J.; van Tooren, M.J.L.","","2008","","","en","conference paper","Royal Aeronautical Society","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2e20b60e-587b-45f6-93fd-5f23e238acc3","http://resolver.tudelft.nl/uuid:2e20b60e-587b-45f6-93fd-5f23e238acc3","Numerical and experimental results of the airflow in the Delft University KiteLab","Breukels, J.; Ockels, W.J.","","2007","","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d9c1765f-1f22-46f6-aa18-8d2d4118d9e5","http://resolver.tudelft.nl/uuid:d9c1765f-1f22-46f6-aa18-8d2d4118d9e5","The economic performance of supply chain(s) served by the mega freight transport vehicles","Janic, M.","","2014","This paper deals with the economic performances of supply chain(s) served by different including the mega freight transport vehicles. These performances are considered as a dimension of the supply chain’s sustainability together with the infrastructural, technical/technological, operational, environmental, and social performances. The supply chain(s) consists of the spoke and hub supplier(s) and the hub and spoke consumer(s) of goods/freight shipments. The economic performances include the inventory, handling, and transport cost of goods/freight shipments processed in the chain(s). The analytical model is developed for estimating the above-mentioned economic performances of the generic configuration of supply chain(s) operating according to the specified scenario(s) under given conditions. Then, the model is applied to the intercontinental supply chain exclusively served by the conventional and mega container ships aiming at investigating their effects/impacts on the chain’s economic performances.","supply chain(s); economic performances; analytical models; mega container ships","en","conference paper","City Net Scientific Research Center","","","","","","","","Civil Engineering and Geosciences / Aerospace Engineering","Transport & Planning / Control & Operations","","","",""
"uuid:f1526ee5-521c-4378-b935-e8b9d993b8a3","http://resolver.tudelft.nl/uuid:f1526ee5-521c-4378-b935-e8b9d993b8a3","Two-dimensional and transient thermal model of the continuous tape laying process","Skandali, M.; Jansen, K.M.B.; Koussios, S.; Sinke, J.; Benedictus, R.","","2015","The purpose of this study is to simulate the two-dimensional, transient and continuous heat transfer during the thermoset Automated Tape Laying (ATL) process. The heat transfer analysis is coupled with a cure kinetics model of the thermoset prepreg tapes used for the process. Unlike most studies, the process is modelled in a Lagrangian framework and is based on the realistic boundary conditions of the ATL such as the stepwise laying down of the tapes. The model results provide information about the temperature values at any time and any location inside the thermoset composite tapes. The temperature simulation results of the model were compared with experiments. Three layers of unidirectional prepreg tapes were laid down on an aluminium mould by the TU Delft ATL machine. The experimental results were obtained from thermocouples and pyrometers placed at various locations in the lay-up and on the robotic head, respectively. The comparison between the numerical and experimental results generated three main findings. First, the pyrometer values and the thermocouple values provide insight into how important is the contact between the mould and the first layer. Secondly, the temperature fading out which was witnessed by the thermocouple measurements and could not entirely be captured by the model provided information about the influence of the heat transfer coefficients on the model predictions. Thirdly, the peak temperature magnitudes of the numerical predictions appeared to generally compare well with the experimental results. Overall, the code can be used for different parameter values such as different line speed, heated length and power of the heat source and, can predict the temperature distribution inside the composite.","tape laying; cure; heat transfer; numerical","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:6d6cebba-ddea-46e4-b0bf-71650484450b","http://resolver.tudelft.nl/uuid:6d6cebba-ddea-46e4-b0bf-71650484450b","Error convergence of the Least-Squares Spectral Element formulation of the linear advection-reaction equation","Van Dalen, W.R.; Gerritsma, M.I.","","2006","This paper discusses the use of the Least-Squares Spectral Element Method in solving the linear, 1-dimensional advection-reaction equation. Well-posedness of the Least-Squares formulation will be derived. The formulation and its results will be compared to the standard Galerkin Spectral Element Method.","least-squares formulation; spectral methods; Galerkin formulation; advectionreaction equation","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:657a8db8-981f-4389-8bdd-2ff1ee5f0c1e","http://resolver.tudelft.nl/uuid:657a8db8-981f-4389-8bdd-2ff1ee5f0c1e","Setting up a Company Performance Measurement Methodology for the Aerospace Industry: Deduction from the Automotive Industry","Beelaerts van Blokland, W.W.A.; Elferink, N.H.; Van der Zwan, F.M.","","2010","Theories on value creation, co-innovation and co-development and lean enterprise have gained in popularity in recent times. This research has taken aim at extending the investigation on how to quantify companies’ capabilities in creating value for their stakeholders. A theoretical framework was adopted to build the performance measurement method on. This framework identifies five performance indicators of company performance: competition performance, financial performance, manufacturing capability, innovation capability and supply chain relationships. Due to the limited availability of data in aviation industry, use was made of data from the automotive industry. Data from 33 automotive OEMs was collected from which a set of variables was constructed. The behavior and relations of these variables were investigated and eventually five variables were selected, one for each performance indicator. Using multiple regression techniques weight factors were determined for each variable and a linear model was constructed, expressing a company performance index. This linear model allows assessing and comparing the performance of different companies over an arbitrary period of time. For the automotive OEMs this was qualitatively shown to work. The model was then adapted to fit the aerospace OEMs and the weight factors were recalculated. Unfortunately, due to the limited availability of data for aerospace OEMs, it was not possible to obtain great insights into the behavior and relations of the variables for these aerospace companies. Moreover, the weight factors of the linear model could not be determined with much accuracy. To solve this, it is recommended that for future research data collection continues and that in some years the research is redone with more data, allowing statistical analysis to be able to detect smaller effects.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3001044c-4357-438c-9a5d-e017175f977a","http://resolver.tudelft.nl/uuid:3001044c-4357-438c-9a5d-e017175f977a","Utilizing Uncertainty Multidisciplinary Design Optimization for Conceptual Design of Space Systems","Yao, W.; Guo, J.; Chen, X.; Van Tooren, M.","","2010","With progress of space technology and increase of space mission demand, requirements for robustness and reliability of space systems are ever-increasing. For the whole space mission life cycle, the most important decisions are made in the conceptual design phase, so it is very crucial to take uncertainties into consideration in this initial phase to assure a feasible, reliable and robust conceptual design baseline which dominates the later design direction and life cycle cost. To enhance space system design quality in the conceptual design phase, the utilization of Uncertainty Multidisciplinary Design Optimization (UMDO) in the systems engineering process is systematically studied in this paper. The UMDO theory is introduced and its application in space system design is studied considering the complexity of the system. A small satellite system design case is further discussed to demonstrate the efficacy of UMDO in improving the space system design.","Uncertainty Multidisciplinary Design Optimization; conceptual design; space system engineering","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:237f29b5-c907-4d26-aa5f-70631197284c","http://resolver.tudelft.nl/uuid:237f29b5-c907-4d26-aa5f-70631197284c","Utlrasonic welding of thermoplastic composites with flat energy directors: Influence of the thickness of the energy director on the welding process","Palardy, G.; Fernandez Villegas, I.","","2015","This paper presents a detailed experimental examination of the influence of the thickness of flat energy directors (ED) on the ultrasonic welding (USW) process for carbon fibre/polyetherimide composites. Three thicknesses of flat ED were compared: 0.06 mm, 0.25 mm and 0.50 mm. Power and displacement data for 0.06 mm-thick EDs did not clearly show the stages of the process and the location of the optimum for best weld quality. Consequently, an investigation of samples welded at different stages in the welding process had to be performed. For 0.06 mm-thick EDs, the optimum was determined to occur at the beginning of the downward displacement of the sonotrode in the vibration phase. The output parameters at the optimum conditions for all thicknesses were compared. Average lap shear strength was found to be lowest for 0.06 mm-thick EDs. Based on the analysis of the fracture surfaces, resin flakes and voids were observed when using the thinnest energy directors, indicating thermal degradation. These observations suggest that thin energy directors are not as efficient as thicker EDs (i.e. 0.25 mm) to achieve preferential heat generation at the weld line, leading to less consistent weld quality.","thermoplastic composites; ultrasonic welding; energy directors; joining","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:e001f9a4-fe96-41dd-87b2-b1fba2b80044","http://resolver.tudelft.nl/uuid:e001f9a4-fe96-41dd-87b2-b1fba2b80044","Effect of cruise altitude and alternative aviation fuels on radiative forcing","Snijders, T.A.; Melkert, J.A.","","2011","The radiative forcing caused by the emissions of jet aircraft is calculated using data from an aircraft performance model. Data from the performance model is needed to calculate the emissions of the aircraft. The sensitivity function and lifetime of the emitted gasses and particles are used to calculate the integrated radiative forcing of the flight of an aircraft. Analysis of a single flight using different fuels and with different cruising altitudes revealed that contrails and aviation induced cirrus cause the largest integrated radiative forcing. This leads to lowest integrated radiative forcing for a cruise altitude of 6 km for both Jet A-1 and Hydrotreated Renewable Jet fuel (HRJ). If contrails and cirrus are omitted the best cruise altitude from the calculated set for Jet A-1 is 11 km while for HRJ 6 km still leads to the lowest integrated radiative forcing.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:40a10e00-0fde-44a4-a95b-a74a711f6e13","http://resolver.tudelft.nl/uuid:40a10e00-0fde-44a4-a95b-a74a711f6e13","Design and testing of an aeroelastically tailored wing under manoeuvre loading","Werter, N.P.M.; Sodja, J.; De Breuker, R.","","2015","The design methodology and testing of an aeroelastically tailored wing subjected to manoeuvre loads is presented in this paper. The wing is designed using an aeroelastic analysis tool that is composed of a closely coupled nonlinear beam model and a vortex lattice aerodynamic model. The globally convergent method of moving asymptotes is used to derive an optimal layup design for a constant and variable stiffness wing. In addition a quasiisotropic wing is designed in order to provide baseline reference data. Each wing design is manufactured and tested in the wind tunnel. Lift and root bending moment coefficient and wing deformation have been measured during the test. Measurements were used to validate the numerical results. The agreement between the numerical results and measurements was very good. The comparison yielded an average absolute difference of less than 10% in the case of lift and root bending moment coefficient and an average absolute difference of less than 5% in the case of the wing tip out-of-plane deformation.","aeroelasticity; aeroelastic tailoring; load alleviation; design; experiment","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:f6da89bd-b155-4545-90ac-8a4548c15489","http://resolver.tudelft.nl/uuid:f6da89bd-b155-4545-90ac-8a4548c15489","The generation of deformation damage during fatigue loading in Al-Cu alloy studied by the Doppler Broadening technique","Ruiz-Ripoll, M.L.; Schut, H.; Van Dijk, N.H.; Alderliesten, R.C.; Van der Zwaag, S.; Benedictus, R.","","2011","We have investigated the evolution of damage during fatigue loading in Al–Cu 2024-T3 alloys using the positron annihilation Doppler Broadening (DB) technique. This technique enables us to monitor in a non destructive way, at the atomic and vacancy level, the formation of deformation defects and their interaction with solute atoms at selected stages of fatigue testing. The changes in the S and W Doppler Broadening parameters are linked to the changes in fatigue behavior at lower stress levels. The material was tested under constant amplitude fatigue loading at four different stress levels and DB tests were conducted at selected stages of fatigue lifetime. The results are compared to those obtained during static tensile tests.","","en","conference paper","IOP Publishing","","","","","","","","Aerospace Engineering","Aerspace Structures and Materials","","","",""
"uuid:c37fdb5b-0845-49b0-9ff8-eafc4daf7866","http://resolver.tudelft.nl/uuid:c37fdb5b-0845-49b0-9ff8-eafc4daf7866","Flexible Tethered Kite with Moveable Attachment Points, Part I: Dynamics and Control","Williams, P.; Lansdorp, B.; Ockels, W.","","2007","Tethered kite technology is one potential means of harnessing energy available in high altitude winds. In an efficient and practical system, the kite is required to fly in cyclic patterns that maximize net power produced per cycle. At the same time, the tether length must be controlled to ensure the system does not expend more energy than it produces. This can be a challenging problem when the intermittency of the wind speed and direction, as well as unsteady wind components, are taken into account. This paper is the first of two that studies the dynamics and control of a flexible kite. In this part, a highly simplified dynamic model of the kite is derived based on a hinged, two-plate representation. This first approximation considers aerodynamic forces produced by the plates as a function of their instantaneous angle of attack. The plates are constrained to have the same yawing angle, but are unconstrained in pitch and roll. The combined pitch and roll of the system is controlled by means of moveable attachment points for the tether(s). Both stationkeeping and timevarying trajectories are considered, for which feedback control is applied for tracking.","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:55fa76ad-7b7a-4586-a66b-bd021170a87b","http://resolver.tudelft.nl/uuid:55fa76ad-7b7a-4586-a66b-bd021170a87b","Multidisciplinary Design and Optimization Framework for Aircraft Box Structures","Van Dijk, R.E.C.; Zhao, X.; Wang, H.; Van Dalen, F.","","2012","Competitive aircraft box structures are a perfect compromise between weight and price. The conceptual design process of these structures is a typical Multidisciplinary Design and Optimization effort, normally conducted by human engineers. The iterative nature of MDO turns development into a long and costly process. Knowledge-Based Engineering can be used to automate this process by capturing relevant design process knowledge, which is then re-used inside a computer application. This research will introduce a parametric, generative box model that has been developed using KBE techniques. The generality and rule-basedness of this model allows for the automatic generation of a wide range of box configurations and variants, thereby enabling a thorough exploration of the design space. Structural and price analyses tools have been coupled to the box model to generate the required discipline-specific performance data. With the product model and coupled analysis tools ready, the goal is to automatically optimize for minimum weight and price without human intervention. The design of Gulfstream 650 rudder is considered as initial use case, the first experiences of which are discussed in this paper.","multidisciplinary design optimization; knowledge-based engineering; knowledge engineering; aircraft box structures; design automation; cost estimation; finite elements modeling","en","conference paper","Royal Aeronautical Society","","","","","","","2013-08-10","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:dd59bbc2-2ab7-4e54-8627-4dff28f8787e","http://resolver.tudelft.nl/uuid:dd59bbc2-2ab7-4e54-8627-4dff28f8787e","Optimal Trajectories for Tethered Kite Mounted on a Vertical Axis Generator","Williams, P.; Lansdorp, B.; Ockels, W.","","2007","Tethered kite technology promises the enable the efficient extraction of energy from high altitude winds. One possible concept for converting the wind energy into electricity is to generate useful work at the ground by using a tether. The tether is able to drive a generator in one of two ways: either the tether is wound and unwound, or the tether is attached to a lever arm that creates a torque on the generator. The latter concept, which uses a vertical axis generator, is explored in this paper. A simplified dynamic model of the system is used to optimize the kite motion to give the maximum power generated per operating cycle. The results show that the average optimal power generated per cycle is proportional to the kite area and the cube of the wind speed. Experimental results of a remotely controlled kite are also briefly reviewed.","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:cdaadcdc-f5d9-4459-bd5d-ad6a58d05af8","http://resolver.tudelft.nl/uuid:cdaadcdc-f5d9-4459-bd5d-ad6a58d05af8","Plasmas for Transition Delay","Kotsonis, M.; Boon, P.; Veldhuis, L.","","2009","This paper describes the experimental investigation of the properties of Dielectric Barrier Discharge (DBD) actuators aimed at transition delay techniques. A wide range of geometrical configurations are tested as well as several electrical operational conditions. For the majority of the measurements statistical data for the induced flow field are obtained and for a limited selection of actuators, high sample-rate time resolved measurements are also conducted. All measurements are made in still flow in order to eliminate free-stream effects on the induced velocities. Results show the formation of a thin near-wall jet which could be used as a flow control device.","plasma actuators; experimental study; active wave cancellation; transition delay","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:8e3722e7-dab4-413f-90e1-1eedbdeef1b3","http://resolver.tudelft.nl/uuid:8e3722e7-dab4-413f-90e1-1eedbdeef1b3","The influence of fiber-matrix adhesion on the linear viscoelastic creep behavior of CF/PPS composites","Motta Dias, M.H.; Jansen, K.M.B.; Luinge, H.; Nayak, K.; Bersee, H.E.N.","","2014","The influence of fiber-matrix adhesion on the linear viscoelastic creep behavior of as received and surface modified carbon fiber (AR-CF and SM-CF, respectively) reinforced polyphenylene sulfide (PPS) composite materials was investigated. Short-term tensile creep tests were performed on ±45° specimens under four different isothermal condition; 70, 80, 90 and 100°C. As a preliminary step to obtain the time-temperature master curve, as well as to characterize the changes in matrix dominated properties over storage time, physical aging effects were evaluated on both systems using the short-term test method established by Struik. The results showed that the surface treatment carried out in the SM-CF improved fiber-matrix adhesion, enhancing the mechanical performance of CF/PPS composites but with minor effects on the creep response. Increasing retardation times with physical aging was observed in all test conditions. Compared to temperature effects, physical aging showed to have a small contribution on the creep behavior of CF/PPS composites.","Viscoelastic Creep Behavior; Physical Aging; CF/PPS Composites; Time Aging-Time Superposition; Time Temperature Superposition Principle (TTSP)","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:a8509a49-d05e-4812-a518-8baee2162269","http://resolver.tudelft.nl/uuid:a8509a49-d05e-4812-a518-8baee2162269","A model for cooperation between humans and intelligent systems","Van Paassen, M.M.R.; Mulder, M.; Abeloos, A.L.M.","","2000","","aircraft cockpit; adaptive interface; intelligent interface; automation; human factors","en","conference paper","European Communities","","","","","","","","Aerospace Engineering","","","","",""
"uuid:50d894cf-88fe-4ecb-87ee-e1f1128b7763","http://resolver.tudelft.nl/uuid:50d894cf-88fe-4ecb-87ee-e1f1128b7763","Least-squares spectral element methods for compressible flows","Gerritsma, M.I.","","2008","","","en","conference paper","University of Pretoria","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7a6d39d8-482c-4aac-a319-86216d29b057","http://resolver.tudelft.nl/uuid:7a6d39d8-482c-4aac-a319-86216d29b057","Multi-level and quasi-Newton acceleration for strongly coupled partitioned fluid-structure interaction","Kreeft, J.J.; Weghs, M.; Van Zuijlen, A.H.; Bijl, H.","","2011","Two reduced order models are presented for the simulation of physically strong coupled fluid-structure interaction problem, based on computationally partitioned flow and structure solvers. The reduced order models used are a class of quasi-Newton coupling methods to obtain a stable solution and to reduce the number of subiterations. The second reduced order model is a multi-level acceleration in with coarse grid computations are performed in order to reduce computational costs. Finally an adaptive multi-level strategy is described, that contains an indicator for when to switch from coarse to fine grid level and vice versa.","fluid-structure interaction; reduced order modeling; quasi-Newton coupling; multi-level acceleration; adaptivity","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:6b1414ee-8e09-4c97-8d67-cc96af129ae7","http://resolver.tudelft.nl/uuid:6b1414ee-8e09-4c97-8d67-cc96af129ae7","Heavy Plasma NAPALM Propulsion Simulation Code","Lörincz, I.; Rugescu, R.D.; Kohlenberg, J.; Prathaban, M.","","2010","The NAPALM project addresses a new and revolutionary space propulsion system, able to deliver a very high specific impulse through a new working fluid and accelerator principle for the electric plasma thruster. The new motor will impressively exceed, by between ten and sixty percent, the vacuum specific impulse of all existing electric and thermo-electric rocket engines. The accomplishment is based on a new working medium, comprised of relatively high-mass gasified nanoparticles that will be accelerated up to very high kinetic energies. While all current electric thrusters are only able to deliver up to 15.000s specific impulse, the new thruster is expected to deliver between 18.000 and over 30.000s specific impulse. This extraordinary property will increase in the equal amount the deliverable ideal velocity during an interplanetary mission. This increased exit velocity conveys into an equal amount of propellant saving, for any equivalent mission performance. Within the range of low thrust levels, a particularly efficient application of the new thruster is in the attitude control of orbital spacecraft, which will save large amounts of propellant, in comparison to the chemical attitude control units and to other existing electrical thrusters. Additionally, the NAPALM thruster will deliver an absolute thrust of more than 0.1 Newton for every mass flow rate of 1 milligram/second and thus an absolute vacuum thrust exceeding 18 Newton is expected.","plasma engine; electric propulsion; nano-materials","en","conference paper","International Research Alliance for Science and Technology","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:1ce8347b-16b2-4d96-a62f-e22d09027f7e","http://resolver.tudelft.nl/uuid:1ce8347b-16b2-4d96-a62f-e22d09027f7e","Modeling and control of a kite on a variable length flexible inelastic tether","Williams, P.; Lansdorp, B.; Ockels, W.","","2007","","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:70031de8-ecc0-4320-a4ce-76a0961b104c","http://resolver.tudelft.nl/uuid:70031de8-ecc0-4320-a4ce-76a0961b104c","Aeroelastic tailoring and structural optimisation using an advanced dynamic aeroelastic framework","Werter, N.P.M.; De Breuker, R.","","2015","Driven by a need to improve the efficiency of aircraft and reduce the fuel consumption, composite materials are applied extensively in the design of aircraft. A dynamic aeroelastic framework for the conceptual design of a generic composite wing structure is presented. The wing is discretized in several spanwise sections, where each section has a number of laminates throughout the cross-section, each having their own stiffness and thickness. The model uses a geometrically nonlinear beam model linearized around the nonlinear static aeroelastic equilibrium position coupled to a continuous-time state-space unsteady aerodynamic model to obtain the dynamic aeroelastic response. Two optimizations are run under aeroelastic and structural constraints: one, a quasi-isotropic wing to serve as a reference solution and two, a fully tailored wing clearly showing the benefit of aeroelastic tailoring and the use of the present framework for conceptual wing design.","aeroelasticity; aeroelastic tailoring; wing design","","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:61e0a9dc-10c8-4392-9ade-b7182e1f794e","http://resolver.tudelft.nl/uuid:61e0a9dc-10c8-4392-9ade-b7182e1f794e","Jean-Etienne Liotard und Karoline Luise von Baden: Eine Geschichte der Pastelle","Sauvage, L.L.F.","","2015","Das Rijksmuseum in Amsterdam beherbergt nach dem Musée d’Art et d’Histoire in Genf die zweitgrößte Sammlung von Pastellgemälden von Jean-Etienne Liotard (1702-1789). Im Hinblick auf die Wiedereröffnung des Museums 2013 wurde im Jahr 2007 ein großes Restaurierungs- und Forschungsprojekt zu den Pastellen initiiert. Die 23 Werke Liotards wurden aus dem Rahmen genommen und dokumentiert; 13 von ihnen wurden restauriert. Um die von Liotard verwendeten Techniken zu rekonstruieren, wurden sowohl Materialproben als auch schriftliche Quellen herangezogen. Neben seinem Traité des principes et règles de la peinture (1781) bilden die erhaltenen Unterlagen seiner einzigen Schülerin in der Pastellmalerei, Karoline Luise von Baden (1723-1783), einen einmaligen und unmittelbaren Beleg für Liotards Praxis. Die Untersuchung der Beziehung zwischen dem Schweizer Künstler und seiner Schülerin führte zur Wiederentdeckung einer Pastellkreidenprobe des Herstellers Bernard-Augustin Stoupan (1701-1775) Zusammenhang mit den technischen Beobachtungen stehen, die an Liotards Pastellen gemacht wurden. Eine eingehende Untersuchung von Liotards Pastelltechniken im Allgemeinen wurde bereits im Jahr 2014 veröffentlicht.","","de","conference paper","Deutscher Kunstverlag GmbH","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:5a471644-e32e-4033-b322-c91b4d5ff296","http://resolver.tudelft.nl/uuid:5a471644-e32e-4033-b322-c91b4d5ff296","Comparison of regional and gobal GRACE gravity field models at high latitudes","Gunter, B.C.; Wittwer, T.; Stolk, W.; Klees, R.; Ditmar, P.","","2009","In this study we address the question of whether regional gravity field modeling techniques of GRACE data can offer improved resolution over traditional global spherical harmonic solutions. Earlier studies into large, equatorial river basins such as the Amazon, Zambezi and others showed no obvious distinction between regional and global techniques, but this may have been limited by the fact that these equatorial regions are at the latitudes where GRACE errors are known to be largest (due to the sparse groundtrack coverage). This study will focus on regions of higher latitude, specifically Greenland and Antarctica, where the density of GRACE measurements is much higher. The regional modeling technique employed made use of spherical radial basis functions (SRBF), complete with an optimal filtering algorithm. Comparisons of these regional solutions were made to a range of other publicly available global spherical harmonic solutions, and validated using ICESat laser altimetry. The timeframe considered was a 3 year period spanning from October 2003 to September 2006.","","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:73658655-2114-4fa4-81a6-aa50d0eab600","http://resolver.tudelft.nl/uuid:73658655-2114-4fa4-81a6-aa50d0eab600","A combined experimental with simulation approach to calibrated 3D strain measurement using shearography","Goto, D.T.; Groves, R.M.","","2010","This paper is concerned with the development of a calibrated 3D shearography strain measurement instrument, calibrated iteratively, using a combined mechanical-optical model and specially designed test objects. The test objects are a cylinder loaded by internal pressure and a flat plate under axial load. Finite element models of the samples, combined with optical models of the shearography system, allow phase maps to be simulated for subsequent comparison with experimental phase maps from the shearography instrument. The algorithm to extract the strain maps from the phase maps includes an error compensation for in-plane strains on curved surfaces, measurement channel redundancy, variations in the shear magnitude due to object shape and the optical characteristics of the imaging system. The improvement introduced by the error compensation techniques is verified by the opto-mechanical simulation and its effect is demonstrated experimentally on maps of displacement gradient.","3D Shearography; strain measurement; error analysis","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Optical Non-Destructive Testing Laboratory","","","",""
"uuid:539602cb-2ab9-4225-a49b-186c6e90934e","http://resolver.tudelft.nl/uuid:539602cb-2ab9-4225-a49b-186c6e90934e","Paparazzi: How to make a swarm of Parrot AR Drones fly autonomously based on GPS","Remes, B.D.W.; Hensen, D.; Van Tienen, F.; De Wagter, C.; Van der Horst, E.; De Croon, G.C.H.E.","","2013","","","en","conference paper","","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:d88b032c-5c10-4613-b2d1-d7b16581c711","http://resolver.tudelft.nl/uuid:d88b032c-5c10-4613-b2d1-d7b16581c711","Capturing the switch between point tracking and boundary avoiding pilot behaviour in a PIO event","Brinkerink, N.; Pavel, M.D.","","2008","","","en","conference paper","Royal Aeronautical Society","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a8c5c104-d2f1-4d19-b68a-2cec80784b25","http://resolver.tudelft.nl/uuid:a8c5c104-d2f1-4d19-b68a-2cec80784b25","Opto-mechanical modelling and experimental approach to the measurement of aerospace materials using shearography and thermal loading","Krutul, E.C.; Groves, R.M.","","2011","This paper is concerned with the modelling of the complete opto-mechanical measurement system, including shearography instrument, loading technique and the response of the object under test and the comparison of the simulation results with experimental results. To show the applicability of this technique, the response of an aluminium flat plate sample under thermal load was analysed. First a finite element model of the plate was generated, using an experimentally measured temperature profile. The strain and displacement values obtained from the finite element model were used to simulate the phase-map in the optical part of the model. The simulated phase maps were then compared qualitatively with experimental phase maps measured using shearography. This approach is suitable to understand the response of components under load and to predict anomalies such as defects, thereby making the analysis of measured phase maps easier and less empirical.","shearography; thermal loading; opto-mechanical model","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerospace Materials and Manufacturing","","","",""
"uuid:f5f73ecd-45c2-42dc-9d05-6adebf834aa5","http://resolver.tudelft.nl/uuid:f5f73ecd-45c2-42dc-9d05-6adebf834aa5","Three-dimensional velocity obstacle method for UAV deconflicting maneuvers","Jenie, Y.I.; Van Kampen, E.J.; De Visser, C.C.; Ellerbroek, J.; Hoekstra, J.M.","","2015","Autonomous systems are required in order to enable UAVs to conduct self-separation and collision avoidance, especially for flights within the civil airspace system. A method called the Velocity Obstacle Method can provide the necessary situational awareness for UAVs in a dynamic environment, and can help to generate a deconflicting maneuver.This paper focuses on the assessment of the Velocity Obstacle Method application and its ability to resolve various conflict situations in three dimensional space. This assessment results in a redefinition of the criteria of avoidance. A novel technique is introduced to support the avoidance decision, by representing the conflict situation in various avoidance-planes. Several new definitions to support the method are introduced. This method is then implemented in three-dimensional simulations for UAVs in cases of conflict, in which more than one option of resolution is provided.","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:05b58c75-b74f-48ac-905d-d202e31be958","http://resolver.tudelft.nl/uuid:05b58c75-b74f-48ac-905d-d202e31be958","Lamb wave detection in prepreg composite materials with fibre Bragg grating sensors","Miesen, N.; Mizutani, Y.; Groves, R.M.; Sinke, J.; Benedictus, R.","","2011","This paper demonstrates that existing Structural Health Monitoring (SHM) techniques have potential during the production phase in addition to their application for maintenance and for in-flight monitoring. Flaws occur during composite fabrication in industry, due to an imperfect process control and human errors. This decreases production efficiency and increases costs. In this paper, the monitoring of Lamb waves in unidirectional carbon fibre (UD-CFRP) prepreg material is demonstrated using both Fibre Bragg Gratings (FBG)s and piezolectric acoustic sensors, and that these SHM sensors may be used for flaw detection and production monitoring. The detection of Lamb waves in a one ply thick sheet of prepreg UD-CFRP material is demonstrated for an FBG sensor aligned with the carbon fibre orientation and bonded to the surface of the prepreg, Furthermore, the velocity of Lamb waves in prepreg UD-CFRP in different orientations is investigated. Finally the successful detection of a material crack in a prepreg UD-CFRP sheet using the Lamb wave detection method is demonstrated.","FBG; composites; damage detection; Lamb waves","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerospace Materials and Manufacturing","","","",""
"uuid:e2d6e3d0-d29a-4aeb-815b-fac159002ce6","http://resolver.tudelft.nl/uuid:e2d6e3d0-d29a-4aeb-815b-fac159002ce6","SkelTre - Fast Skeletonisation for Imperfect Point Cloud Data of Botanic Trees","Bucksch, A.; Lindenbergh, R.C.; Menenti, M.","","2009","Terrestrial laser scanners capture 3D geometry as a point cloud. This paper reports on a new algorithm aiming at the skeletonisation of a laser scanner point cloud, representing a botanical tree without leafs. The resulting skeleton can subsequently be applied to obtain tree parameters like length and diameter of branches for botanic applications. Scanner-produced point cloud data are not only subject to noise, but also to undersampling and varying point densities, making it challenging to extract a topologically correct skeleton. The skeletonisation algorithm proposed in this paper consists of three steps: (i) extraction of a graph from an octree organization, (ii) reduction of the graph to the skeleton and (iii) embedding of the skeleton into the point cloud. The results are validated on laser scanner point clouds representing botanic trees. On a reference tree, the mean and maximal distance of the point cloud points to the skeleton could be reduced from 1.8 to 1.5 cm for the mean and from 15.6 to 10.5 cm for the maximum, compared to results from a previously developed method.","skeleton; terrestrial laser scanning; tree analysis; point cloud","en","conference paper","Eurographics","","","","","","","2010-03-28","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:ef22d8e0-e221-4da9-b863-6ebf15abccf1","http://resolver.tudelft.nl/uuid:ef22d8e0-e221-4da9-b863-6ebf15abccf1","Relationship Between Optimal Gain and Coherence Zone in Flight Simulation","Correia Gracio, B.J.; Valente Pais, A.R.; Van Paassen, M.M.; Mulder, M.; Kelly, L.C.; Houck, J.A.","","2011","In motion simulation the inertial information generated by the motion platform is most of the times different from the visual information in the simulator displays. This occurs due to the physical limits of the motion platform. However, for small motions that are within the physical limits of the motion platform, one-to-one motion, i.e. visual information equal to inertial information, is possible. It has been shown in previous studies that one-to-one motion is often judged as too strong, causing researchers to lower the inertial amplitude. When trying to measure the optimal inertial gain for a visual amplitude, we found a zone of optimal gains instead of a single value. Such result seems related with the coherence zones that have been measured in flight simulation studies. However, the optimal gain results were never directly related with the coherence zones. In this study we investigated whether the optimal gain measurements are the same as the coherence zone measurements. We also try to infer if the results obtained from the two measurements can be used to differentiate between simulators with different configurations. An experiment was conducted at the NASA Langley Research Center which used both the Cockpit Motion Facility and the VisualMotion Simulator. The results show that the inertial gains obtained with the optimal gain are different than the ones obtained with the coherence zone measurements. The optimal gain is within the coherence zone.The point of mean optimal gain was lower and further away from the one-to-one line than the point of mean coherence. The zone width obtained for the coherence zone measurements was dependent on the visual amplitude and frequency. For the optimal gain, the zone width remained constant when the visual amplitude and frequency were varied. We found no effect of the simulator configuration in both the coherence zone and optimal gain measurements.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:cab05522-147e-4920-8df0-676f658db676","http://resolver.tudelft.nl/uuid:cab05522-147e-4920-8df0-676f658db676","Increasing system performance and flexibility: Distributed computing and routing of data within the fast formation flying mission","Maessen, D.C.; Gunter, B.C.; Verhoeven, C.J.M.; Gill, E.K.A.","","2008","In 2007, the Tsinghua University, China, and the Delft University of Technology, The Netherlands, have agreed to jointly define, develop and operate the Formation for Atmospheric Science and Technology demonstration (FAST) mission. FAST will allow for a synoptic evaluation of global aerosol data and altitude profiles of the cryosphere with two cooperating micro-satellites flying in formation in 2011. One of the many technology demonstrations planned for the FAST mission involves the use of distributed space-based computing. This technique can be used to maximize the computational power available in a formation of small satellites, as well as reducing downlink budgets by processing data in flight. Its implementation on FAST is discussed in the paper. The formation flying and distributed computing demonstrations call for a communication link between the two FAST spacecraft. Important to the design of the link is that it does not necessarily need to be a direct link. In fact, during a part of the mission, such a direct link will be impossible due to the relative orbit geometry of the satellites. This requires an alternative routing of the inter-satellite communications via ground stations or via commercial satellite communication constellations. This flexible solution is explored, with special emphasis paid to the issues related with communication with a commercial satellite communication constellation.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:1deacbc6-9857-4896-97e7-85bd37a405de","http://resolver.tudelft.nl/uuid:1deacbc6-9857-4896-97e7-85bd37a405de","Maximum Buckling Load Design of General Cross-section Cylinders Using Lamination Parameters","Khani, A.; Abdalla, M.M.; Gürdal, Z.","","2010","For a non-circular cylinder the radius of curvature changes around the circumference. Therefore for constant stiffness non-circular cylinders, some specific locations in the circumference are more prone to buckle. The same problem exists for circular cylinders with non-uniform loading in the cross-section like a cylinder under bending. This explanation brings to the mind the idea of tailoring the material such that the material potential is used more efficiently and if possible all parts of the cylinder contribute in the buckling phenomenon. Since the changes in the radius of curvature and/or loading happens in the circumferential direction, tailoring the material properties in the circumferential direction is a logical pattern. By assigning a certain number of half-waves in the longitudinal direction, the buckling eigen-value problem is solved to find the buckling load and circumferential mode shapes. The inverse of buckling load is approximated using a homogeneous, conservative formulation to increase the computational efficiency during optimisation. This is a hybrid approximation expanded in terms of stiffness linearly and reciprocally. Multi-modal optimisation problem is formulated to minimise inverse of critical buckling factor. Variable stiffness design is compared with the quasi-isotropic design.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:46990fa6-26cc-420b-8b3e-2ca9f08f940d","http://resolver.tudelft.nl/uuid:46990fa6-26cc-420b-8b3e-2ca9f08f940d","Parameter space exploration of bio-inspired hover kinematics","Vandenheede, R.B.R.; Bernal, L.P.; Morrison, C.L.; Humbert, S.","","2012","An experimental investigation of the parameter space of biologically inspired hover kinematics for flapping wings is conducted. The present research continues earlier work conducte at a Reynolds number of 4.8 x 10^3 and with a reduced frequency of 0.38. The kinematics considered are pitch and plunge motions based on the kinematics of the Agrius Convolvuli, which include a hover kinematic ignoring elevation angle, a hover kinematic incorporating a correction for elevation angle, and a harmonic pitch/plunge motion of the same amplitude. A parameter space exploration of these baseline motions is performed. First, the reduced frequency is increased to a value of 0.7. Second, a phase lag of 10%T and -10%T are introduced to study the effects of advanced and delayed rotation. Force measurements are reported and the results compared to the baseline motions. An increase in reduced frequency increases the average thrust coefficient substantially for all motions. The efficiency decreases slightly for all but the pure sinusoidal motion. Introducing a phase lag of 10% of the period changes the forces significantly. For delayed rotation thrust production and efficiency decrease by a large amount. Increases in thrust occur in the advanced rotation cases, although there is a penalty in efficiency.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:6d780387-ab74-419e-84ea-1c5da80e8e3d","http://resolver.tudelft.nl/uuid:6d780387-ab74-419e-84ea-1c5da80e8e3d","Understanding the peculiarities of rotorcraft, pilot, couplings","Pavel, M.D.; Padfield, G.D.","","2008","","","en","conference paper","American Helicopter Society","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6e98580d-7f76-493e-a74e-b3f73542b32a","http://resolver.tudelft.nl/uuid:6e98580d-7f76-493e-a74e-b3f73542b32a","Validation of the Beddoes-Leishman Dynamic Stall Model for Horizontal Axis Wind Turbines using MEXICO data","Pereira, R.; Schepers, G.; Pavel, M.D.","","2011","The aim of this study is to assess the load predicting capability of a classical Beddoes-Leishman dynamic stall model in a horizontal axis wind turbine (HAWT) environment, in the presence of yaw-misalignment. The dynamic stall model was tailored to the HAWT environment, and validated against unsteady thick airfoil data. Subsequently, the dynamic stall model was implemented in a blade element-momentum (BEM) code for yawed flow, and the results were compared with aerodynamic measurements obtained in the MEXICO (Model Rotor Experiments under Controlled Conditions ) project on a wind turbine rotor placed in a large scale wind tunnel. In general, reasonable to good agreement was found between the BEM model and MEXICO data. When large yawmisalignments were imposed, poor agreement was found in the downstroke of the movement between the model and the experiment. Still, over a revolution the maximum normal force coefficient predicted was always within 8% of experimental data at the inboard stations, which is encouraging especially when blade fatigue calculations are being considered.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:3e906651-ff82-433c-a80c-4049f15d5b2c","http://resolver.tudelft.nl/uuid:3e906651-ff82-433c-a80c-4049f15d5b2c","A new approach to forced flapping for the ornicopter","Van Gerwen, D.J.; Van Holten, T.","","2008","","ornicopter; forced flapping; reaction torque","en","conference paper","Optimage Ltd., on behalf of ICAS","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2a5614ef-42a0-4330-86b5-efc8ff927e06","http://resolver.tudelft.nl/uuid:2a5614ef-42a0-4330-86b5-efc8ff927e06","Architectural scene rapid reconstruction based on features","Ding, Y.; Zhang, J.Q.","","2008","Retrieve the structure of model and the motion of camera is a classical and hot topic in computer vision and photogrammetry. A lot of automatic or semiautomatic techniques have been developed to optimize the retrieving processing from accuracy, stability and reality perspectives. These techniques are variant from data source, feature selection for matching, feature clustering and 3D model representation. The optimization algorithm and a completely automatic system are still under exploring. In this paper, we use some image-based algorithms for feature selection and matching of 3D man-made scene reconstruction. We present a robust point matching algorithm with RANSAC estimator, and compare two methods of line matching in a complex man-made environment. We point out the degeneracy when use epipolar line as a constraint to match line, instead use a global optimization method. Our experiments show that the proposed method is robust in a complex man-made scene.","3D reconstruction; feature matching; differential evolution; visualization; robust estimation","en","conference paper","International Society for Photogrammetry and Remote Sensing","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:86c8c002-7d1e-410f-ab2e-36122120e797","http://resolver.tudelft.nl/uuid:86c8c002-7d1e-410f-ab2e-36122120e797","Buckling and first-ply failure optimization of stiffened variable angle tow panels","Jeliazkov, M.; Sardar Abadi, P.M.; Lopes, C.S.; Abdalla, M.M.; Peeters, D.M.J.","","2015","A computationally efficient two-level design methodology is developed for the optimization of stiffened compression loaded panels having variable stiffness panels as their skin. In the first step extensive bay panel optimization is performed using a Rayleigh-Ritz energy method coupled with a specialized Genetic Algorithm. Results in agreement with lamination parameter optima are achieved by employing distinct steered-fiber configurations in different layers. Additionally, a local equivalent laminate robustness constraint is applied, and it is shown to have detrimental effect on the buckling performance of variable stiffness layups. The optimal results obtained are used to characterize the plate buckling response in laminate stiffness space. An approximate analytical model is developed to analyze the buckling-related failure modes of the stiffened panel. Panels are optimized for a variety of configurations and loads. Variable stiffness designs achieve up to 20% weight reduction compared to their straight fiber counterparts, while 5-7% improvements are possible when a local 10% rule is enforced. Varying the fiber orientation is also shown to increase the weight-optimal stiffener spacing. The results indicate that the application of the concept is most promising for lightly loaded configuration, which are driven primarily by buckling, and not material failure. Alternatively, high weight savings are achieved in cases where large stiffener spacing is enforced by non-performance related requirements.","buckling; optimization; stiffened panels; variable stiffness laminates","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Computational Mechanics","","","",""
"uuid:7bc61dad-2efd-4669-97d1-d753fc298a5d","http://resolver.tudelft.nl/uuid:7bc61dad-2efd-4669-97d1-d753fc298a5d","Arrival Trajectory Optimization on Noise Impact using Interval Analysis","Yu, H.; Mulder, J.A.","","","The CleanEra project is initiated by the Faculty of Aerospace Engineering at Delft University of Technology. Significant reduction of noise impact on perimeters of airports via arrival trajectory optimization is considered as one of the major targets of the project. In this paper, an aircraft model and its acoustic performance are introduced to assist the development of the optimization tool since the CleaenEra project is still ongoing. Interval analysis is explained in details because interval algebra is employed to deal with real intervals rather than real numbers in the so-called interval-related optimization algorithms. The largest advantage of such algorithms is that they are capable of finding the global optimum out of the multiple local minima to a given optimization problem. Two numerical examples are presented to show the usefulness of such algorithms while solving both static and dynamic optimization problems. In the end, a third example is given to demonstrate the applicability of the proposed optimization tool to trajectory optimization for arriving passenger aircraft.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:ec41e926-e040-4483-bb24-2a742cce0b4a","http://resolver.tudelft.nl/uuid:ec41e926-e040-4483-bb24-2a742cce0b4a","Test facility development for testing of micro-thrusters at TU-Delft","Zandbergen, B.T.C.; Janssens, S.; Valente, F.; Perez-Grande, D.; Koopmans, R.","","2010","The development of highly integrated and compact micro-satellites and the need for a higher precision of positioning and attitude control in space missions has stimulated the development of micro-propulsion systems. At TU-Delft, investigations are focusing on non-chemical, thermal propulsion. TU-Delft is also collaborating with TNO and UTwente to develop a mini-propulsion system (T3-?ps) to be flown in 2011 as part of the MicroNed Nanosatellite Program. To complement these developments, the TU-Delft is developing test facilities and equipment for on ground testing of such systems. The most critical need is the ability to take thrust and impulse bit measurements with adequate accuracy and resolution. To this purpose, the TU-Delft has developed a thrust stand capable of measuring thrust levels in the range 100-1000mN and minimum impulse bit of 5mNs as well as a smaller stand capable of measuring thrusts ranging from 0.5-50mN and a minimum impulse bit of 0.05mNs. In collaboration with Universidad Politécnica de Madrid, we are currently investigating the development of a thrust stand capable of measuring thrust levels in the range 10-2000?N with an accuracy of ± 2?N and minimum impulse bit of 0.25?Ns. In addition, for thruster testing under rough vacuum conditions, a Heraeus vacutherm oven has been successfully adapted. This paper describes the test facility developments made at the TU-Delft as part of the MicroNed program. We will describe the design objectives, and the design methods used, provide an outline of the thrust stands and the vacuum facility and talk about their development status and how well they perform. Also test results will be presented to show the performances of the various thrust stands and the benefits of testing under rough vacuum conditions.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:86dc5507-e4a2-4efb-8ace-7926a0b75812","http://resolver.tudelft.nl/uuid:86dc5507-e4a2-4efb-8ace-7926a0b75812","Perception of Combined Visual and Inertial Low-Frequency Yaw Motion","Valente Pais, A.R.; Van Paassen, M.M.; Mulder, M.; Wentink, M.","","2010","Following a previous study in the Simona simulator on perception of coherent visual and inertial cues in a flight simulator, an experiment is performed in the Desdemona simulator to investigate the influence of the frequency of visual and inertial stimuli on the limits of the perceived coherence zone. The coherence zone is defined as the range of inertial motion amplitudes that, though not being a physical match to the visual cues, are still perceived by subjects as coherent. The main hypothesis tested is that the semi-circular canals dynamics influence the internal comparison between the visually and inertially perceived self-velocity. Furthermore, the results between the Simona and Desdemona studies are compared. In general, the effect of amplitude and frequency on the measured coherence zones follow the same trends as in the previous study: the coherence zone width increases with increasing visual cue amplitude and the point of mean coherence decreases with respect to the one-to-one line for the higher amplitudes. The results for the low frequency and low amplitude stimulus might be affected by the inertial sensory threshold, making it difficult to draw definite conclusions about the posed hypothesis. The results between the two simulator studies are different in terms of absolute values, but the trends are the same.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:aec95116-9e2e-4a63-a27a-c48d17669cfe","http://resolver.tudelft.nl/uuid:aec95116-9e2e-4a63-a27a-c48d17669cfe","Error budget of terrestrial laserscanning: Influence of the intensity remission on the scan quality","Bucksch, A.; Lindenbergh, R.C.; Van Ree, J.","","2009","Terrestrial laser scanning (TLS) is a surveying technology to measure distances to surfaces in the spherical surrounding of the scanner instrument. In contrast to pulse, i.e. time of flight scanners, phase based scanners emit a modulated wave signal that allows for determining the object distance from the returned phase pattern. Because of their high scanning speed, phase based instruments are getting more and more popular. It is clear from literature and practice that, because of the interaction between the laser light and the object, the characteristics of the object surface have a large influence on the measurement quality. Still, a quantitative insight in the quality of scanning results is missing. This publication will compare two phase based scanners, the Imager5003 from Zoller und Fröhlich and the HS880 from Faro. We investigate the scan quality of both scanners for a variety of surfaces with different reflection characteristics. For this purpose scans of an Esser Test Chart TE 109 were made with both scanners. The test chart consists of six different grey patches ranging from 71% remission white to 0.05% remission black. The chart was scanned from a distance of 4 m in a stable environment. In order to compare the scanning results of both scanners a patch wise analysis is made of (i) the number of points scanned, (ii) the intensities values of the scanned points, and (iii) the reliability and precision of a local plane adjustment. It turns out that for both scanners the measurement noise is significantly increasing with decreasing remission. An insight in the amount of absorbed and reflected energy per grey value patch will be part of the analysis results. An overall conclusion of the presented experiment is that the two scanners differ only in extreme cases from the specifications given by the manufacturers.","Terrestrial Laser Scanning; Error Budget; Surface Reflectivity","en","conference paper","Siberian State Academy of Geodesy","","","","","","","","Aerospace Engineering","DEOS","","","",""
"uuid:0911faec-eee7-40c7-ac52-35d951d0c5ad","http://resolver.tudelft.nl/uuid:0911faec-eee7-40c7-ac52-35d951d0c5ad","A comparison of smart rotor control approaches using trailing edge flaps and individual pitch control","Lackner, M.A.; van Kuik, G.A.M.","","2009","Modern wind turbines have been steadily increasing in size, and have now become very large, with recent models boasting rotor diameters greater than 120 m. Reducing the loads experienced by the wind turbine rotor blades is one means of lowering the cost of energy of wind turbines. Wind turbines are subjected to significant and rapid fluctuating loads, which arise from a variety of sources including: turbulence in the wind, tower shadow, wind shear, and yawed flow conditions. ""Smart rotor control"" concepts have emerged as a major topic of research in the attempt to reduce fatigue loads on wind turbines. In this approach, aerodynamic load control devices are distributed along the span of the wind turbine blade, and through a combination of sensing, control, and actuation, these devices dynamically control the loads on the blades. This research investigates the load reduction potential of smart rotor control devices, namely trailing edge flaps (TEFs), in the operation of a 5 MW wind turbine in the aeroelastic design code ""GH Bladed."" Specifically in this paper, the fatigue load reductions achieved using trailing edge flaps are evaluated, and the performance is compared to another promising load reduction technique, individual pitch control. A feedback control approach is implemented for load reduction, which utilizes a multi-blade coordinate transformation, so that variables in the rotating frame of reference can be mapped into a fixed frame of reference. Single input single output (SISO) control techniques for linear time invariant (LTI) systems are then employed to determine the appropriate response of the TEFs based on the loads on the blades. The use of TEFs and this control approach is shown to e®ectively reduce the fatigue loads on the blades, relative to a baseline controller. The load reduction potential is also compared to an alternative individual pitch control approach, in the time and frequency domain. The effects on the pitch and power systems are briefly evaluated, and the limitations of the analysis are assessed.","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:50076fef-2a4d-4086-b20b-d13187e367e7","http://resolver.tudelft.nl/uuid:50076fef-2a4d-4086-b20b-d13187e367e7","Alloy by design: A materials genome approach to advanced high strength stainless steels for low and high temperature applications","Lu, Q.; Xu, W.; Van der Zwaag, S.","","2016","We report a computational 'alloy by design' approach which can significantly accelerate the design process and substantially reduce the development costs. This approach allows simultaneously optimization of alloy composition and heat treatment parameters based on the integration of thermodynamic, thermo-kinetics and a genetic algorithm optimization route. Novel steel compositions and associated key heat treatment parameters are identified so as to realize the target microstructure for applications either at the room temperature (ultra-high strength maraging stainless steel) or at high temperatures (creep resistant steels). Solid solution strengthening and precipitation hardening are the two strengthening mechanisms employed to improve the strength of designed steels. Either one of them or their combination is optimized in the four steel families considered. Each model is validated by analyzing the strengthening contributions in existing steels and by experimental characterization of prototype alloys. Very good agreement between experimental performance and model predictions is found. All newly designed alloys are predicted to outperform existing high end reference grades.","alloy design; precipitation hardening; solid solution strengthening; matrix","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:9ee747d8-637a-4074-81fa-b00da14e723b","http://resolver.tudelft.nl/uuid:9ee747d8-637a-4074-81fa-b00da14e723b","Pouring time into space","Schneiders, J.F.G.; Azijli, I.; Scarano, F.; Dwight, R.P.","","2015","A method is proposed to reconstruct instantaneous velocity from time-resolved tomographic PTV, employing both instantaneous velocity and velocity material derivative. This improves upon current techniques by not only including penalization of velocity divergence, but also requiring consistency with the temporal derivative of the PTV particle tracks. Hence the procedure is christened as pouring time into space. The aim of the proposed technique is to increase spatial resolution of tomographic PTV in cases where it is limited by the seeding concentration. An inverse problem is solved to find the velocity field that minimizes a cost function including next to instantaneous velocity and its divergence, also the velocity material derivative. The velocity and its material derivative are related through the vorticity transport equation and the problem is minimized using the L-BFGS algorithm, where gradients are evaluated efficiently using an adjoint implementation of the method. The procedure is assessed numerically using results from a simulated PTV experiment in a turbulent boundary layer from DNS, and experimentally using tomographic PIV measurements in a jet flow. Both the numerical and experimental assessment show that the proposed technique yields improved accuracy of the velocity field in between the measured points over penalization of divergence only, thereby demonstrating that the temporal information available in time-resolved tomographic PTV can be leveraged to increase reconstruction quality of instantaneous velocity.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:18d88d33-d4e2-46f0-8319-703c58b8a346","http://resolver.tudelft.nl/uuid:18d88d33-d4e2-46f0-8319-703c58b8a346","Importance sampling of severe wind gusts","Bos, R.; Bierbooms, W.A.A.M.; Van Bussel, G.J.W.","","2015","An important problem that arises during the design of wind turbines is estimating extreme loads with sufficient accuracy. This is especially difficult during iterative design phases when computational resources are scarce. Over the years, many methods have been proposed to extrapolate extreme load distributions from relatively short time series with “mean turbulence”. In this work, however, we focus on finding the response to extreme gusts based on the ability to generate conditional turbulent wind fields. Load distributions can then be constructed on the basis of a Monte Carlo method with importance sampling.","extreme loads; wind gusts; Monte Carlo method; importance sampling","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:4da625fa-2db6-46b0-9e25-d02bc7b86bec","http://resolver.tudelft.nl/uuid:4da625fa-2db6-46b0-9e25-d02bc7b86bec","The effect of particle image blur on the correlation map and velocity measurement in PIV","Elsinga, G.E.; Van Oudheusden, B.W.; Scarano, F.","","2005","In PIV particle image blur is usually observed near fluid optical interfaces, i.e. shock waves, and thin flow structure with large density variations, e.g. shear layers and boundary layers. In such an environment the particle image is not only subject to blur, but is also displaced from its actual position due to refraction, which is denoted as optical displacement. In this study particle image blur near a shock wave is investigated in relation to the auto- and cross-correlation map, measurement accuracy and confidence level. The results from a numerical study are supported by PIV measurements of a shock wave in a supersonic wind tunnel. It is demonstrated that particle images are blurred in the direction of lower refractive index (directional blurring). The particle images are also skewed. Therefore particle image blur not only causes correlation peak broadening due to the fact that the particle images increase in size, but more importantly can introduce an asymmetry in the correlation peak and in turn introduce a small bias error in the measured velocity. However, experimental results indicate that particle image blur itself is not the main cause for the increase in measurement uncertainty near shock waves, but that the reduced accuracy can be attributed to the optical displacement. The observation of particle image blur can be used as a detection criterion for a qualitative assessment of the optical displacement. Certain combinations of experimental parameters (viewing angle, f/# and interrogation window size) yield significant errors in the measured velocity. Under certain circumstances optical distortion can become so strong to introduce an unphysical acceleration within the shock wave, visualized as an inflection point with positive slope in the velocity profile across the shock. The study provides some practical suggestions to limit the effect of aero-optical distortion on the velocity measurement.","aerodynamics; particle image velocimetry; particle image blur; shock wave","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:23c72254-5397-4e02-8b8c-7bec68d5870d","http://resolver.tudelft.nl/uuid:23c72254-5397-4e02-8b8c-7bec68d5870d","Liotard's pastels: Techniques of an 18th-century pastellist","Sauvage, L.L.F.; Gombaud, C.","","2015","In 2007 the Rijksmuseum, Amsterdam initiated a conservation and research project on framed pastels by the Swiss artist Jean-Etienne Liotard. For the first time, 21 pastels were unframed and available for documentation, examination and technological analysis. In order to reconstruct both his workshop practice and his palette, materials used by the artist were examined as well as his production process. The first results of this project are presented here with a preliminary palette of colours. Liotard’s working methods were studied – from the supports to the application of colours – and then compared to various sources. The 1762 treatise on parchment making by Jérôme De La Lande, L’art de faire le parchemin, provided very interesting information on vellum support for pastel painting. Apart from the Traité des principes et règles de la peinture (1781) written by Liotard himself, the archives of his only pupil in pastel painting, Princess Karoline Luise von Hessen-Darmstadt, can be considered a unique and direct record of Liotard’s practice.","","en","conference paper","Archetype","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:e195c3ce-e1fc-4d27-a4e3-8ac150f52e79","http://resolver.tudelft.nl/uuid:e195c3ce-e1fc-4d27-a4e3-8ac150f52e79","Towards a Multi-Fidelity Approach for CFD Simulations of Vortex Generator Arrays","Florentie, L.; Van Zuijlen, A.H.; Bijl, H.","","2014","This paper is the starting point for the development of a multi-fidelity modeling approach for vortex generators (VG) arrays, where a fully resolved VG model will be coupled with an approximate model in order to improve both accuracy and flexibility without increasing the required computational cost. As a first step thereto, an analysis of the ability of the BAY-model to simulate incompressible flows around a VG on a flat plate has been performed. Results are presented for several turbulence models and using different cell selection approaches, where comparison is made with fully resolved VG results. In addition to a coarse uniform mesh, the BAY-model has been evaluated on a densely gridded mesh in order to distinguish between model and mesh related discrepancies.","vortex generators; CFD; turbulence modeling; multi-fidelity modeling","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:c78d8369-34fc-4126-9bd9-9c987a99a4b4","http://resolver.tudelft.nl/uuid:c78d8369-34fc-4126-9bd9-9c987a99a4b4","Assembly, integration and testing of the Delfi-C³ nanosatellite","Brouwer, G.F.; Ubbels, W.J.; Vaartjes, A.A.; Te Hennepe, F.","","2008","At the Delft University of Technology, the Delfi-C3 3-unit Cube Sat was finalised for launch on PSLV C9. An overview is presented about manufacturing, assembly, integration and verification activities on subsystems and Proto Flight Model (PFM) until delivery for launch. Delfi-C3 is the first Dutch university satellite and the fourth Dutch satellite. It was designed and built by the faculties of Aerospace Engineering and Electrical Engineering, Mathematics and Computer Science. Industry partners provided payloads: Autonomous Wireless Sun Sensors and Thin Film Solar Cells. Attention is paid to the experiences and lessons learned in this student project. The test plan and activities may serve as a valuable scheme for the next university satellite and other cube sats. During the hardware phase of the project, firstly development tests were done (e.g. deployment mechanisms, antenna pattern), followed by functional performance tests of subsystems (electronics, measurement systems, payload interface electronics, power system, communications system and attitude control behaviour). The complete satellite was subjected to a test program, consisting of vibration-, thermal vacuum-, deployment-, communication- and performance tests. With regular health and functional checks, the satellite status was verified for changes during testing.","Delfi-C3; university satellite; student project; testing, sun-sensor; wireless; thin film solar cells; assembly; integration; test","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:e19ddf3e-9372-41e3-a9ec-a739be3e8993","http://resolver.tudelft.nl/uuid:e19ddf3e-9372-41e3-a9ec-a739be3e8993","Integrating aircraft warning systems","Mulder, Mark; Pedroso, O.; Mulder, Max; Van Paassen, M.M.R.","","2000","","agents; multi-agent systems; GPWS; TCAS; integration","en","conference paper","European Communities","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6fb8b968-5682-4b78-9faa-ae5c7b7dcc71","http://resolver.tudelft.nl/uuid:6fb8b968-5682-4b78-9faa-ae5c7b7dcc71","Geodetic sensor systems and sensor networks: Positioning and applications","Verhagen, S.; Grejner-Brzezinska, D.; Retscher, G.; Santos, M.; Ding, X.; Gao, Y.; Jin, S.","","2009","This contribution focuses on geodetic sensor systems and sensor networks for positioning and applications. The key problems in this area will be addressed together with an overview of applications. Global Navigation Satellite Systems (GNSS) and other geodetic techniques play a central role in many applications like engineering, mapping and remote sensing. These techniques include precise positioning, but also research into non-positioning applications like atmospheric sounding using continuously operating GNSS networks. An important research area is multi-sensor system theory and applications to airborne and land-based platforms, indoor and pedestrian navigation, as well as environmentalmonitoring. The primary sensors of interest are GNSS and inertial navigation systems. Furthermore, Interferometric Synthetic Aperture Radar (InSAR) is recognized as one of the most important state-of-the-art geodetic technologies used for generation of Digital Elevation Models and accurately measuring ground deformations","current research issues; GNSS; InSAR","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:3e13d49e-46fe-40af-9d3d-5da250189c1d","http://resolver.tudelft.nl/uuid:3e13d49e-46fe-40af-9d3d-5da250189c1d","Cost effective manufacturing processes and materials used for the construction of the Superbus","Terzi, A.; Ockels, W.J.","","2008","The Superbus, rendered in Figure 1, is a new concept for public transportation. It is sustainable, fast, economic, and appealing and transports passengers and goods from point to point and drives at high speed (250 km/h) on its dedicated and relatively cheap infrastructure. In this paper the material used, the cost effective tooling and manufacturing processes for the construction of the Superbus are presented. First, the materials used for the achievement of the structural design targets in combination with the lightweight requirements will be described in their application to the Superbus, which uses a composite chassis, IXIS thermoplastic bodywork and Lexan polycarbonate glazing. Then, the tooling and manufacturing processes utilized for the construction of the vehicle will be discussed in terms of the optimization between final good product and cost constrains.","","en","conference paper","International Federation of Automotive Engineering Societies","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:ad53a613-0912-4dfb-86ce-4a555d52b90e","http://resolver.tudelft.nl/uuid:ad53a613-0912-4dfb-86ce-4a555d52b90e","Using multi-beam echo sounder backscatter data for sediment classification in very shallow water environments","Amiri-Simkooei, A.R.; Snellen, M.; Simons, D.G.","","2009","In a recent work described in Ref. [1], an angle-independent methodology was developed to use the multi-beam echo sounder backscatter (MBES) data for the seabed sediment classification. The method employs the backscatter data at a certain angle to obtain the number of sediment classes and to discriminate between them by applying the Bayes decision rule to multiple hypotheses. This method is adopted and applied to very shallow-water applications. There are two issues when dealing with riverbed classification in shallow water. Shallow water depth results in a small beam-footprints and hence a small number of scatter pixels, which makes the classification results to be less discriminative. The significant bottom slopes will also affect the backscatter data and hence the classification results. We aim to handle these issues using the high resolution bathymetry and backscatter data. A methodology is developed to estimate the precise bottom slopes using the high resolution bathymetry data. Corrections are then applied to convert the arrival angle of the signal into the true incident angle and to compensate for the effect of the ensonified area. The high resolution backscatter data allows one to reduce the statistical fluctuations using an averaging procedure. The methodology will then be tested on a MBES data set from the river Waal, the Netherlands. The acoustic classification results are correlated with the mean grain sizes of the sediment obtained from core analysis of the grab samples. The dependence of acoustic backscatter classification on sediment physical properties is verified by observing a significant positive correlation coefficient of 0.70 between the classification results and sediment mean grain sizes of the grab samples.","multi-beam echo-sounders (MBES); backscatter data; slope correction; Bayes decision rule; Gaussian distribution","en","conference paper","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:c84dcfc7-5d9f-4aec-b9df-2f064ab667d8","http://resolver.tudelft.nl/uuid:c84dcfc7-5d9f-4aec-b9df-2f064ab667d8","Implementation of a reliable date bus for the Delfi nanosatellite programme","Cornejo, N.E.; Bouwmeester, J.; Gaydadjiev, G.N.","","2009","The Delfi-n3Xt nano-satellite is the second Dutch universitysatellite currently being developed at the Delft University of Technology (TUD) as successor of the Delfi-C3 that has been successfully launched in April 2008. Compared to Delfi-C3, the Delfi-n3Xt platform provides significant advancements to the platform: a high-speed downlink, three-axis attitude control and a single-point of failure free battery. In total five payloads will be flown that generate a considerable larger amount of data compared to Delfi-C3that implies, as well, a robust and adequate design for the data handling system that interlinks the various embedded systems on board. This paper examines the design and implementation of a fault tolerant data bus architecture as part of the satellite Command and DataHandling Subsystem (CDHS). Delfi-C3 carries an I2C protocol based implementation that currently experiencesproblems with data corruption and timeouts and is therefore subject of scrutiny andanalysis in this paper. In particular, the relationship between error rates, master-slave speeds and processing overheads is evaluated in detail. After a tradeoff study betweenseveral bus standards for Delfi-n3Xt, the choice is once again an I2Cimplementation, but with significant hardware and software improvements over the previous design. In terms of hardware, shielding and bus protection considerationsare included in the very early stages of design. With respect to software, special care is taken in dealing with the varying clock speeds between slaves and masters, correct data handling and the feasibility of error detection and correction codes, as the amount of data generated by thepayloads of the Delfi-n3Xt is significantly higher. The final result of this research is the selection of the most adequate reliability techniques and their implementation. This I2Cbus targeted middleware is intended for usage in the complete Delfi nanosatelliteprogramme at TUD and for several other space applications in general.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:1b01b37d-2e98-4185-b0f9-8f4e4248f577","http://resolver.tudelft.nl/uuid:1b01b37d-2e98-4185-b0f9-8f4e4248f577","Design and evaluation of a taxi display with integrated data link","Stroosma, O.; Hoogeboom, P.","","1999","","aircraft navigation; ground operations; cockpit displays; data link; SMGC; A-SMGC","en","conference paper","Group D Publications Ltd","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7b004234-8c64-4457-929b-ab45edb684b8","http://resolver.tudelft.nl/uuid:7b004234-8c64-4457-929b-ab45edb684b8","A posteriori uncertainty quantification of PIV-derived pressure fields","Azijli, I.; Sciacchitano, A.; Ragni, D.; Palha da Silva Clerigo, A.; Dwight, R.P.","","2015","The present work proposes a methodology for the a posteriori quantification of the uncertainty of pressure data retrieved from PIV measurements. It relies upon the Bayesian framework, where the posterior distribution (probability distribution of the true velocity, given the PIV measurements) is obtained from the prior distribution (prior knowledge of the velocity, e.g., within a certain bound or divergence-free) and the distribution representing the PIV measurement uncertainty. Once the posterior covariance matrix of the velocity is known, it is propagated through the discretized Poisson equation for pressure. Numerical assessment of the proposed method on a steady Lamb Oseen vortex shows excellent agreement with Monte Carlo simulations, while linear uncertainty propagation underestimates the uncertainty of the pressure by up to 30%. The method is finally applied to an experimental test case of a turbulent boundary layer in air, obtained using time-resolved tomographic PIV. The pressure reconstructed from tomographic PIV data is compared to a microphone measurement conducted simultaneously at the wall to determine the actual error of the former. The comparison between actual error and estimated uncertainty shows the accuracy of the proposed method for uncertainty quantification of pressure data from tomographic PIV experiments: for a 95% confidence level, 93% of the data points fall within the estimated uncertainty bound with the Eulerian approach, and 90% with the Lagrangian approach. When using the prior knowledge that the velocity field should be divergence-free, these values are 98% with the Eulerian approach and 94% with the Lagrangian approach. The Lagrangian approach results in more accurate reconstructed pressure fields than the Eulerian approach. Also, enforcing the divergence-free constraint is found to result in a more accurate reconstructed pressure field. Both observations also follow from the uncertainty quantification, through a decrease in the estimated uncertainty.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:6da0f5e1-e629-4a62-a847-a07438587ae7","http://resolver.tudelft.nl/uuid:6da0f5e1-e629-4a62-a847-a07438587ae7","Automatic detection of buried channel deposits from dense laser altimetry data","Possel, B.M.J.; Lindenbergh, R.C.; Storms, J.E.A.","","2010","The formation of the current Rhine-Meuse delta mainly took place during the last 12 000 years. Consecutive avulsions, i.e. sudden changes in the course of river channels, resulted in a complicated pattern of sandy channel deposits, surrounded by peat and clay. Knowledge of this pattern is not only interesting from a geohistorical viewpoint, but is also essential when planning and maintaining constructions like roads and dikes. Traditionally, channel deposits are traced using labor intensive soil drilling. Channel deposits are however also recognizable in the polder landscape by small local elevation changes due to differential compaction. The purpose of this research is to automatically map channel deposits based on a structural analysis of high resolution laser altimetry data. After removing infrastructural elements from the laser data, local feature vectors are built, consisting of the attributes slope, curvature and relative elevation. Using a maximum likelihood classifier, 75 million gridded laser points are divided into two classes: buried channel deposits and other. Results are validated against two data sets, an existing paleographic map and a set of shallow drilling measurements. Validation shows that our method of channel deposit detection is hampered by signal distortion due to human intervention in the traditional polder landscape. Still it is shown that relative young deposits (4 620 to 1 700 years Before Present) can be extracted from the laser altimetry data.","LIDAR; structural classification; shallow subsurface; channel deposits","en","conference paper","International Society of Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:74a8a8be-6cf7-4a2d-bd8d-1874597ac2e1","http://resolver.tudelft.nl/uuid:74a8a8be-6cf7-4a2d-bd8d-1874597ac2e1","Least-squares spectral element method with implicit time integration for the inviscid Burgers equation","Oldenziel, G.; Gerritsma, M.I.","","2006","This paper describes the use of the Least-Squares Spectral Element Method for non-linear hyperbolic equations. The one-dimensional inviscid Burgers equation is specifically subject of investigation. A second order backward difference method is used for time stepping. The behaviour of this formulation is examined by application to a testcase where a moving shock develops. For this testcase an hp-convergence study is performed.","Least-Squares Spectral Element Methods; hyperbolic equations; hp-convergence","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6348ff23-1d7d-49f2-bf93-f08a693b5fbc","http://resolver.tudelft.nl/uuid:6348ff23-1d7d-49f2-bf93-f08a693b5fbc","Climber Motion Optimization for the Tethered Space Elevator","Williams, P.; Ockels, W.J.","","","The tethered space elevator could provide a revolutionary means for enabling cheap transportation to geostationary altitude and beyond. Assuming that such a system can be built, one of the dynamic design problems is determining a means of moving the elevator along the tether so as to minimize the residual librational motion of the elevator ribbon and counterweight. In particular, this paper studies this problem from the point of view of dynamic optimization. A simplified dynamic model of the elevator system is derived that accounts for the fundamental libration mode and the motion of the elevator. The model is used to solve an optimal control problem that results in zero final librational motion of the ribbon.","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:e5fa41d8-f83f-4f86-a5cc-aad5ab2cdeb4","http://resolver.tudelft.nl/uuid:e5fa41d8-f83f-4f86-a5cc-aad5ab2cdeb4","Stereo PIV Experiments on Horizontal Axis Wind Turbine Rotor Model","Akay, B.; Micallef, D.; Ferreira, C.S.; Van Bussel, G.J.W.","","2011","This paper sets out to describe the measurements and computations to construct three components of velocity field around the blade. The primary aim of the measurements was to gain insight into the physics of the flow field produced by a horizontal axis wind turbine-HAWT blade. Stereo Particle Image Velocimetry experiments were performed on a two-bladed HAWT rotor in the open jet facility. Three components of velocity on 2D planar measurement planes were obtained from the defined field of views. The three components of velocity at the different radial positions are analysed in the present paper by comparing the experimental results with the panel code results. Besides having an insight about the flow field around the blade section, this comparison enables to improve and validate the panel code. The measurements show very well agreement with the computations except at the tip trailing edge region which is expected. The key observation of this work is inboard motion of the tip vortex. Also, clear outward motion of the radial flow on the suction side of the inboard sections of the blade is observed in the measurements and computations.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:f5797790-c205-4b21-a5ca-422a479629f9","http://resolver.tudelft.nl/uuid:f5797790-c205-4b21-a5ca-422a479629f9","Preliminary Design of the ""Superbus""","Antonelli, V.; Terzi, A.; Ockels, W.; Beukers, A.","","2007","The present paper presents the structural design of the Superbus. First the overall requirements are described and analyzed, with respect to loads (static and dynamic), stiffness and functional requirements. In order to fulfil the relative targets, two different solutions have been defined and analyzed in the preliminary design. From those, the best option is described. Finally, the description of the production of the vehicle is presented.","Superbus","en","conference paper","Society for the Advancement of Material and Process Engineering (SAMPE)","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures and Materials","","","",""
"uuid:2ae6c0d9-c5cc-4ac9-b4ed-2a62e6071e2c","http://resolver.tudelft.nl/uuid:2ae6c0d9-c5cc-4ac9-b4ed-2a62e6071e2c","Self-heating forecasting for thick laminates testing coupons in fatigue","Lahuerta, F.; Westphal, T.; Nijssen, R.P.L.","","2012","Thick laminate sections can be found from the tip to the root in most common wind turbine blade designs. Obtaining accurate and reliable design data for thick laminates is subject of investigations. Due to the poor thermal conductivity properties of composites and the material self-heating that occurs during the fatigue loading, high temperature gradients may appear through the laminate thickness. In the case of thick laminates in high loads regimes, the centre section temperature might exceed the material operational range, leading to premature failures. In the present work a method to forecast the self-heating of thick laminates in fatigue loading is presented. The mechanical loading is related with the laminate self-heating, via the cyclic energy strain and the energy loss ratio. Based on this internal volumetric heat load a thermal model is built and solved the get the temperature distribution in the transient state. Based on experimental measurements of the energy loss factor for 10mm coupons, the method is described and the resulting predictions are compared with experimental surface temperature measurements on 10 and 30mm UD thick laminate specimens.","","en","conference paper","EAWE European Academy of Wind Energy","","","","","","","","Aerospace Engineering","","","","",""
"uuid:06900f96-8803-4d52-bb28-43b1211495b0","http://resolver.tudelft.nl/uuid:06900f96-8803-4d52-bb28-43b1211495b0","Adverse rotorcraft-pilot coupling: Recent research activities in Europe","Dieterich, O.; Götz, J.; Vu, B.; Pavel, M.D.; Haverdings, H.; Jump, M.","","2008","","APC; RPC; PIO; pilot-in-the-loop; rotorcraft-pilot coupling","en","conference paper","Royal Aeronautical Society","","","","","","","","Aerospace Engineering","","","","",""
"uuid:dc284173-20b9-46ef-9f2c-75a098f7a860","http://resolver.tudelft.nl/uuid:dc284173-20b9-46ef-9f2c-75a098f7a860","Using MBES backscatter strength measurements for assessing a shallow water soft sediment environment","Siemes, K.; Snellen, M.; Simons, D.G.; Hermand, J.P.","","2009","Shallow water naval operations require detailed knowledge of the environmental characteristics. In this context, the BP’07 experiment was carried out in the Mediterranean Sea, south-east of Elba Island, in 2007. Measurements that were taken during this experiment employ a large set of sensors, thereby providing all information required to fully describe the environment. Water depths as measured by multi beam echo sounders (MBES) are found to range from 0 to about 130 meter. The finescale topography reveals that areas of different bottom morphology are present. Information about the physical sediment properties is obtained by bottom grab samples. They indicate the seafloor in the area to be composed of very fine-grained sediments with mean grain sizes ranging from 0.5 to 8 micrometer. In addition, the MBES also allows for classifying the seafloor. The MBES classification approach taken discriminates between sediments in the most optimal way by applying the Bayes decision rule for multiple hypotheses. It employs the MBES backscatter data, averaged per beam, which are assumed to be normally distributed. For shallow water situations, this assumption no longer holds due to the limited number of independent scatter pixels in the beam footprint. Averaging over a series of pings has been applied to restore this assumption. The application of the method results in a map of the acoustic classes in this area, indicating the presence of four different seafloor types. A comparison with other results indicates a correlation between seafloor type and the presence of specific bottom features.","bathymetry; seafloor phenomena; sediments","en","conference paper","IEEE","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:79d9c4d6-6422-47fb-933f-faf43f16e44a","http://resolver.tudelft.nl/uuid:79d9c4d6-6422-47fb-933f-faf43f16e44a","Auralization of novel aircraft configurations","Arntzen, M.; Bertsch, E.L.; Simons, D.G.","","2015","A joint initiative of NLR, DLR, and TU Delft has been initiated to streamline the process of generating audible impressions of novel aircraft configurations. The integrated approach adds to the value of the individual tools and allows predicting the sound of future aircraft before they actually fly. Hence, an existing process for the aircraft design and system noise prediction at DLR has been upgraded to generate the required input data for an aircraft auralization framework developed by NLR and TU Delft. This paper presents the new process and an initial application towards the fully automated auralization of novel aircraft configurations within the conceptual aircraft design phase. Such an early auralization of the new designs enables the aircraft designer to assess the success of selected low-noise measures in an intuitive way in addition to the conventional measures, e.g. noise isocontour areas. The auralization result is able to capture all the predicted noise shielding measures used in the current application and indicates that, for an approach condition, drastically reduced ground noise exposure can be achieved.","","en","conference paper","","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:5294e5fd-373d-44cd-ad19-d8a7ff4be919","http://resolver.tudelft.nl/uuid:5294e5fd-373d-44cd-ad19-d8a7ff4be919","Model generation for the verification of automatically generated mechatronic control software","Foeken, M.J.; Voskuijl, M.; Alvarez Cabrera, A.A.; van Tooren, M.J.L.","","2008","","","en","conference paper","IEEE","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4a33a7b8-2328-4833-8fee-1a4882b2d043","http://resolver.tudelft.nl/uuid:4a33a7b8-2328-4833-8fee-1a4882b2d043","Statistical adaptivity in PIV interrogation for mean flow estimation","Theunissen, R.; Scarano, F.; Riethmuller, M.L.","","2008","","","nl","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:fc8eda20-69e3-4edd-aee2-f2114402a3aa","http://resolver.tudelft.nl/uuid:fc8eda20-69e3-4edd-aee2-f2114402a3aa","Route preliminary demand forecast model","Ghijs, S.S.A.; Elferink, N.H.","","2008","","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f94d9802-1f3a-428a-bb3f-6316be50ce1a","http://resolver.tudelft.nl/uuid:f94d9802-1f3a-428a-bb3f-6316be50ce1a","Aviation and the environment, rating airlines on their co2 efficiency","Van der Zwan, F.M.; Dorland, N.; Ghijs, S.S.A.; Santema, S.C.; Curran, R.","","2009","The aviation industry contributes about 2% to the total global manmade CO2 emissions, which is seen as the main (manmade) greenhouse gas inducing climate change. This paper focuses on the design of a CO2 rating system which makes it possible to make a fair comparison of the environmental performance of airlines with respect to CO2 on the basis of public available data. It is argued that airlines can be best compared on the amount of CO2 emitted per revenue ton kilometer (CO2/ RTK) on the basis of distance sectors. Therefore, an airline is rated on various distance sectors. The CO2 efficiency scores of an airline within a distance sector can then be compared with other airlines. For nine airlines the CO2 efficiency is modeled, and the distance sector boundaries are determined. It is shown that the relative positions of airlines may change when choosing a different boundary, since the CO2 efficiency changes with distance. It is also shown that on the basis of public available information it is difficult to accurately determine the CO2/ RTK of an airline, which is due to lack of detail in public available data. A sensitivity analysis has been performed to show on which parameters information in greater detail is needed.","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:188e3b35-65a2-4114-9f6f-159c63f533e6","http://resolver.tudelft.nl/uuid:188e3b35-65a2-4114-9f6f-159c63f533e6","Homothetic mapping as means to obtain a wide field of view: The Delft Testbed Interferometer","Van Brug, H.; Oostdijck, B.; Snijders, B.; Van der Avoort, C.; Gori, P.M.","","2004","The Delft Testbed Interferometer (DTI) will be presented. The basics of homothetic mapping will be explained together with the method of fulfilling the requirements as chosen in the DTI setup. The optical layout incorporates a novel tracking concept enabling the use of homothetic mapping in real telescope systems for observations on the sky. The requirements for homothetic mapping and the choices made in the DTI setup will be discussed. Finally the first results and the planned experiments will be presented.","multi aperture interferometry; wide field imaging; homothetic mapping","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","SRON","","","",""
"uuid:418b090f-4861-4f24-be6b-84fc510aa3cb","http://resolver.tudelft.nl/uuid:418b090f-4861-4f24-be6b-84fc510aa3cb","Quantifying value flow for aerospace enterprises in business to business markets","Beelaerts van Blokland, W.W.A.; Silfhout, G.J.; Santema, S.C.","","2009","From previous research (JBM, 2008) it is identified that co-development and co-production contributes to customer value. The question has arisen if the co-development and co-production value effects on product level can be identified on enterprise level as well, by testing new identified metrics. If metrics can be identified it will be possible to compare enterprises on the capability to process “value flow”. This research delves into the correlations between the research and development value, customer value and supply value, with use of the 3C value flow model. The following research question is proposed: How to quantify “value flow” for aerospace OEM’s acting in business to business markets? Value flow on enterprise level can be defined as the capability of OEM’s to leverage customer demand value into supply value, by adding own R&D value.","research and development; open-innovation; lean manufacturing; supply chain management","en","conference paper","Copenhagen Business School","","","","","","","","Aerospace Engineering","Aerospace Management and Operations","","","",""
"uuid:20295474-e97b-48ef-96f2-f98c7f39041a","http://resolver.tudelft.nl/uuid:20295474-e97b-48ef-96f2-f98c7f39041a","The Jupiter icy moons explorer (JUICE): Complementarity of the payload in addressing the mission science objectives (abstract)","Grasset, O.; Altobelli, N.; Barabash, S.; Bruzzone, L.; Dougherty, M.; Erd, C.; Fletcher, L.; Gare, P.; Gladstone, R.; Gurvits, L.; Hartogh, P.; Hussmann, H.; Jaumann, R.; Iess, L.; Langevin, Y.; Palumbo, P.; Piccioni, G.; Titov, D.; Wahlund, J.E.","","2014","This presentation will give a status of the JUICE mission in the end of the definition phase, its science scenario, and the observation strategies that are foreseen with a strong emphasis on the complemen-tarity of the suite of instruments. To summarize, the instrument suite on-board JUICE will allow the inte-gration of datasets into a comprehensive multisensor / multitemporal / multiresolution view maximizing the scientific return of the data. This will be demonstrated using six examples that are briefly described in this abstract.","","en","conference paper","NASA","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:8f5cd234-f98c-448e-985b-0f8be380b633","http://resolver.tudelft.nl/uuid:8f5cd234-f98c-448e-985b-0f8be380b633","A mechanical model for the self healing response of coatings based on expansive phases (abstract)","Rey, R.; Javierre, E.; Perez, M.A.; Garcia Espallargas, S.J.; Van der Zwaag, S.; Garcia-Aznar, J.M.","","2011","","coating; self-healing; FEM simulation; mechanical modelling","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:bd7dd84c-3d86-4426-afbf-c5d090f84297","http://resolver.tudelft.nl/uuid:bd7dd84c-3d86-4426-afbf-c5d090f84297","High-temperature hybrid welding of thermoplastic (CF/Peek) to thermoset (CF/Epoxy) composites","Fernandez Villegas, I.; Vizcaino Rubio, P.","","2015","Thermoset composites are widely used for the manufacturing of modern composite aircrafts. The use of thermoplastic composites (TPC) in aerospace applications is, however, gradually increasing owing to their cost-effectiveness in manufacturing and improved damage tolerance. An example of the use of thermoplastic composites in aircraft is the thousands of clips and cleats that connect structural elements in the fuselage of new composite passenger aircrafts, which are press formed from preconsolidated laminates in only a few minutes. Thermoplastic composite and thermoset composite parts are currently joined through mechanical fastening, which is known not to be an optimal joining technique for composites. Nevertheless, the ability of TPC to be welded with little surface preparation and short assembly times poses the question of whether thermoplastic and thermoset composites can be welded together. Hybrid thermoplastic to thermoset composite welding poses two main challenges: firstly, adhesion between the thermoplastic and thermoset resins; secondly, degradation of the thermoset resin when exposed to the welding temperatures. This paper presents a procedure to successfully prevent any negative thermal effects on the thermoset resin during high-temperature welding of thermoplastic to thermoset composites. The procedure is based on reducing the heating time to fractions of a second during the welding process. In order to achieve such short heating times, which are much too short for commercial welding techniques such as resistance or induction welding, ultrasonic welding is used. A particularly challenging scenario is analysed by considering welding of carbon-fibre reinforced poly-ether-ether-ketone (CF/PEEK), with a melting temperature of 340°C, to carbon-fibre reinforced epoxy (CF/epoxy) with a glass transition temperature of 157°C.","joining; composite welding; thermoplastic composites; thermoset composites","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:28895329-9179-493e-a373-a6f3553f8a28","http://resolver.tudelft.nl/uuid:28895329-9179-493e-a373-a6f3553f8a28","On the development of a heuristic routing application for the automatic wire harness design in the aircraft","Zhu, Z.; Van Tooren, M.J.L.; Van der Elst, S.W.G.","","2011","Based on the use of dedicated software tools, Knowledge Based Engineering (KBE) techniques are able to capture and reuse engineering product and process knowledge to reduce time and cost during product development. In this paper a conceptual design of an automatic wire harness routing application is proposed, based on KBE. As the core of this application, the wire harness routing algorithm is discussed in detail. Through comparison with related methods and existing algorithms, a suitable algorithm, named A* is selected. In order to comply with the complex aircraft specific routing environments, the selected algorithm is enhanced with so-called wall-attraction capabilities. The resulting algorithm is called the wall-attraction A* (W*) algorithm, and features a settable parameter that controls the balance between performance and admissibility of the solution. By conducting a set of experiments the influencing parameter is optimized. A case study is finally presented, featuring a conceptual aircraft environment that validates the above theories. Applying the W* algorithm, the wire harness routing application can connect any source and destination nodes satisfying according the relevant constraints meanwhile the valuable time and resources are saved.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:ca415372-6ac0-4e7a-ab66-6e6dbf564e22","http://resolver.tudelft.nl/uuid:ca415372-6ac0-4e7a-ab66-6e6dbf564e22","Evaluation of safety, performance and emissions of synthetic fuel blends in a Cessna Citation II","Snijders, T.A.; Melkert, J.A.","","2011","Prior to being used in aviation, alternative fuels have to be tested thoroughly to ensure safe operation. At Delft University of Technology, a test programme was performed to evaluate the safety, performance and emissions of synthetic fuel blends. During test preparations, compatibility of the synthetic fuel with the aircraft, a Cessna Citation II equipped with Pratt & Whitney Canada JT15D-4 jet engines, was ensured by material and component testing. When safe operation was ensured, on-ground engine test runs were performed. Results indicated good engine operation and reduced fuel consumption with increasing synthetic fuel content. Emission measurements during the engine test runs showed significantly reduced soot and sulphur dioxide emissions and small reductions in carbon monoxide and nitrogen oxides emission over a landing and take-off cycle.","","en","conference paper","l'Association Aeronautique et Astronautique de France","","","","","","","","Aerospace Engineering","","","","",""
"uuid:990b4bc8-9fe6-472d-a662-eb87733d5949","http://resolver.tudelft.nl/uuid:990b4bc8-9fe6-472d-a662-eb87733d5949","Problem of Pareto-Optimal Control for a High Altitude Energy System","Podgaets, A.R.; Ockels, W.J.","","2006","","Laddermill; multi-objective optimal control","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a80941c2-63ac-4711-9a3c-e2933fabf1af","http://resolver.tudelft.nl/uuid:a80941c2-63ac-4711-9a3c-e2933fabf1af","Concept selection for a planetary reflection-seismology system with multiple end-user requirements and mission constraints","Batenburg, P.A.W.; Gill, E.K.A.; Drijkoningen, G.G.; Toxopeus, G.J.","","2010","A study was performed to determine the feasibility of reflection seismology for planetary geology taking into account present-day technology advances. An approach based on end-user requirements was applied to assure the scientific usefulness of the results. Thirty applications of a seismic-reflection system for space applications were determined in cooperation with geologists. The requirements on the seismic system were derived from the end-user requirements, the geologists’ requirements; the seismic image of the subsurface structure. This derivation or seismic system design is a task performed by geophysicists. This process is complex and several aspects and expectations of the to-be-investigated area are required to design the system such that it can perform its task. The process to design the seismic-reflection system for the thirty applications was challenging because of the very limited amount of existing data. Furthermore, an individual design for each application was too time consuming. Instead, this issue was solved by a novel method to systematically and consistently transform the enduser requirements into the the requirements of the reflection seismology system for all the thirty applications. Theoretical and empirical relations were used to determine the required system requirements from the input of the geologists. The study assumed an open setting for mission conditions to allow all possibilities for the use of a reflection-seismology system. The result of this approach was sixty sets of system requirements and nine sets of (basic) mission constraints. On top of that,, the concepts for the reflection-seismology system consisted of three separate concept groups: seismic-wave sources, seismic-wave detectors and deployment methods. These three groups contained seven, five and five concepts respectively which, combined, are 175 concepts for the entire system. Combined, these resulted in 9*6*175 = 94,500 combinations to evaluate. Assessing all these combinations separately was considered too time consuming and error sensitive. The process of concept selection was therefore performed in a stepwise systematic fashion. Prior to concept selection, combination assessment matrices were created as guideline tools for the actual concept selection. This selection was split up into four levels, levels that simulate the mission design, systems and subsystems selection. The methods created for requirement transformation and the concept selection proved to be robust. It could be shown that the applied process protected the end-user requirements.","","en","conference paper","International Astronautical Federation","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:3da885ad-a800-4c78-95aa-a38830b1a9d9","http://resolver.tudelft.nl/uuid:3da885ad-a800-4c78-95aa-a38830b1a9d9","Validating time series of a combined GPS and MERIS Integrated Water Vapor product","Lindenbergh, R.; Van der Marel, H.; Keshin, M.; De Haan, S.","","2009","Increased knowledge of atmospheric water vapor can improve weather predictions and is expected to reduce errors in products derived from GPS and (In)SAR data. At GPS ground stations Integrated Water Vapor (IWV) is estimated from the GPS signal delay with a high temporal resolution. The Envisat MERIS spectrometer obtains spatially dense IWV observations but at limited moments in time. In this research the additional value of MERIS IWV is evaluated when added to GPS IWV for the purpose of obtaining a high quality spatial-temporalwater vapor product. At each of 39 stations, first GPS IWV from surrounding stations is used to produce a two months time series of IWV with a temporal resolution of one hour. Then both GPS and MERIS IWV are used together. The two resulting time series are validated against direct GPS IWV as measured at the station.","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e2b9ea1f-5fa1-47c0-82ad-64d1c74a5378","http://resolver.tudelft.nl/uuid:e2b9ea1f-5fa1-47c0-82ad-64d1c74a5378","The eN method for transition prediction: Historical review of work at TU Delft","Van Ingen, J.L.","","2008","","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:82ce1f47-7c19-4877-b644-9c66d3a803bf","http://resolver.tudelft.nl/uuid:82ce1f47-7c19-4877-b644-9c66d3a803bf","3D Buildings Modelling Based on a Combination of Techniques and Methodologies","Pop, G.; Bucksch, A.K.; Gorte, B.G.H.","","2007","Three dimensional architectural models are more and more important for a large number of applications. Specialists look for faster and more precise ways to generate them. This paper discusses methods to combine methodologies for handling data acquired from multiple sources: maps, terrestrial laser and additional measurements, together with digital images for the purpose of generating the 3D visualization of selected buildings. The information used in this kind of projects may have numerous inputs: 3D laser scanning, total stations, digital photogrammetry, laser altimetry, maps - all of them in combination with data generated from other various disciplines and related to the project’s purpose. All 3D data gathering techniques show significant improvements in resolution and accuracy. In this context, aerial and close range photogrammetry, airborne or terrestrial-based laser scanning, mobile mapping and GPS surveying are also on the same trend. A variety of approaches with different resolutions, accuracies, methods, completion times, stages and costs exist. In this paper, an approach towards 3D modelling of buildings and information collection using combined data from digital photogrammetry, mobile mapping, laser scanning, conventional surveying and cartography-based reconstruction, is considered.","3D modelling; terrestrial laser scanning; visualization; photogrammetry","en","conference paper","","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:61349024-7fa4-400e-add0-dccf561481c7","http://resolver.tudelft.nl/uuid:61349024-7fa4-400e-add0-dccf561481c7","Post-buckled precompressed (PBP) subsonic micro flight control actuators and surfaces","Barrett, R.; Vos, R.; De Breuker, R.","","2007","This paper describes a new class of flight control actuators using Post-Buckled Precompressed (PBP) piezoelectric elements to provide much improved actuator performance. These PBP actuator elements are modeled using basic large deflection Euler-beam estimations accounting for laminated plate effects. The deflection estimations are then coupled to a high rotation kinematic model which translates PBP beam bending to stabilator deflections. A test article using PZT-5H piezoceramic sheets built into an active bender element was fitted with an elastic band which induced much improved deflection levels. Statically the bender element was capable of producing unloaded end rotations on the order of ±2.6°. With axial compression, the end deflections were shown to increase nearly 4-fold. The PBP element was then fitted with a graphite-epoxy aeroshell which was designed to pitch around a tubular stainless steel main spar. Quasi-static bench testing showed excellent correlation between theory and experiment through ±25° of pitch deflection. Finally, wind tunnel testing was conducted at airspeeds up to 120kts (62m/s, 202ft/s). Testing showed that deflections up through ±20° could be maintained at even the highest flight speed. The stabilator showed no flutter or divergence tendencies at all flight speeds. At higher deflection levels, it was shown that a slight degradation deflection was induced by nose-down pitching moments generated by separated flow conditions induced by extremely high angles of attack.","piezoelectric; flight control; post-buckled precompressed; BPB; MAV; UAV","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerospace Structures","","","",""
"uuid:dd5c6b29-766f-4b5d-bd4f-abe194825278","http://resolver.tudelft.nl/uuid:dd5c6b29-766f-4b5d-bd4f-abe194825278","An architecture for probabilitic risk assessment of human-machine systems","Koorn, M.; Van Paassen, M.M.R.","","1998","","","en","conference paper","LAMIH","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7198c05d-40c1-457f-ac65-311ebf5da6dc","http://resolver.tudelft.nl/uuid:7198c05d-40c1-457f-ac65-311ebf5da6dc","Group Purchasing Classification: Symbiotic Relationships in Horizontal Purchasing Cooperation","Waltmans, B.; Reunis, M.R.B.; Schotanus, F.; Santema, S.C.","","2006","","group purchasing; purchasing consortium; classification; symbiotic relationships; allocation","en","conference paper","IMP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0e67bfe5-7125-4605-8514-11ce8ce31d54","http://resolver.tudelft.nl/uuid:0e67bfe5-7125-4605-8514-11ce8ce31d54","Uniqueness and nonuniqueness of the GNSS carrier-phase compass readings","Teunissen, P.J.G.","","2009","In this contribution we analyse the possible nonuniqueness in the least-squares solution of the GNSS carrier-phase compass model. It is shown that this lack of uniqueness may manifest itself in the fixed baseline estimator and therefore in the GNSS compass readings. We present the conditions under which nonuniqueness occurs and give explicit expressions for these nonunique least-squares solutions.","GNSS-compass; ambiguity resolution; attitude nonuniqueness","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:0cb1a6a5-3add-40b8-8ae5-9e6ba95f649c","http://resolver.tudelft.nl/uuid:0cb1a6a5-3add-40b8-8ae5-9e6ba95f649c","Analysis of Air Traffic Controller Workload Reduction Based on the Solution Space for the Merging Task","Mercado Velasco, G.A.; Mulder, M.; Van Paassen, M.M.","","2010","Air traffic controller workload is considered to be an important limiting factor to the growth of air traffic. The difficulty of an air traffic control task can be analyzed through examining the problem’s solution space, that is, all possible vector commands that satisfy the constraints of safety, productivity and efficiency. But apart from deriving metrics for workload, a visualization based on the solution space, resulting in the Solution Space Diagram, could help the controller inmanaging the air traffic. An experiment was conducted in which two different levels of traffic density were tested in order to evaluate the effects of presenting the Solution Space Diagram on controller workload. The experiment entailed the task of merging aircraft into a single route and subjects provided subjective ratings of workload at fixed intervals of time. Depending on traffic level and subject experience, significant effects of the Solution Space Diagram were found on the reduction of controller workload.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:96cd39c8-1c5b-4e44-9ee0-13358795f40d","http://resolver.tudelft.nl/uuid:96cd39c8-1c5b-4e44-9ee0-13358795f40d","GOCE level 2 gravity gradients","Bouman, J.; Fiorot, S.; Fuchs, M.; Gruber, T.; Schrama, E.J.O.; Tscherning, C.C.; Veicherts, M.; Visser, P.N.A.M.","","2011","Two of the GOCE Level 2 products are the gravity gradients (GGs) in the Gradiometer Reference Frame (GRF) and the GGs in the Local North-Oriented Frame (LNOF). The GRF is an instrument frame and the GGs are derived from the L1b GGs. The L1b to L2 GG processing involves corrections for temporal gravity variations, outlier detection and data gap interpolation, as well as the external calibration of the GGs using independent gravity field information. Because of the gradiometer configuration, four out of the six GGs - VXX, VYY, VZZ and VXZ - will have a small error in the Measurement Band (MB), whereas the other two - VXY and VYZ - will have low accuracy. The GRF GGs are rotated to the LNOF that is directly related to the Earth.","","en","conference paper","European Space Agency (ESA)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:4b843285-6895-4886-92c3-2e1edf79ff32","http://resolver.tudelft.nl/uuid:4b843285-6895-4886-92c3-2e1edf79ff32","Automatic registration of terrestrial point cloud using panoramic reflectance images","Kang, Z.","","2008","Much attention is paid to registration of terrestrial point clouds nowadays. Research is carried out towards improved efficiency and automation of the registration process. This paper reports a new approach for point clouds registration utilizing reflectance panoramic images. The approach follows a two-step procedure: pair-wise registration and global registrations. The pair-wise registration consists of image matching (pixel-to-pixel registration) and point clouds registration (point-to-point correspondence), provided the correspondence between image and point cloud (pixel-to-point) is known. The image matching process delivers corresponding points within the overlapping area of two images. These points are matched to their 3D equivalent points within the point clouds. False accepted correspondences are successfully removed by a geometric invariance check. An iterative least-square adjustment completes the pair wise registration. The global registration on all point clouds is obtained by a bundle adjustment using circularly self-closure constraint. The approach is tested with several data sets (indoor and outdoor scenes) acquired by the laser scanner FARO LS 880.","point cloud; registration; terrestrial; automation; image matching; bundle adjustment","en","conference paper","International Society for Photogrammetry and Remote Sensing","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:8bcde1de-84db-4ed1-acb3-2f1186dd5910","http://resolver.tudelft.nl/uuid:8bcde1de-84db-4ed1-acb3-2f1186dd5910","Description and Flow Assessment of the Delft Hypersonic Ludwieg Tube","Schrijer, F.F.J.; Bannink, W.J.","","2008","","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:59cc3256-990f-44fa-8ce5-847984061b5e","http://resolver.tudelft.nl/uuid:59cc3256-990f-44fa-8ce5-847984061b5e","Improved command and data handling system for the Delfi-n3Xt nanosatellite","De Jong, S.; Aalbers, G.T.; Bouwmeester, J.","","2008","The Delfi-C3 nanosatellite successor, Delfi-n3Xt, is currently under development at Delft University of Technology. This nanosatellite based on a three-unit CubeSat form factor has been improved through the implementation of a high-speed downlink, three-axis active attitude control and a single-point-failure free implementation of batteries in the electrical power system. Failure of the batteries will therefore not lead to failure of the primary mission as has, in the past, been the case with many other nanosatellite missions. The functional analysis and design of the command and data handling system (CDHS) of Delfi-C3 and the improved CDHS architecture of Delfi-n3Xt are presented in this paper. The main design drivers for the CDHS of Delfi-C3 were the available technology and the absence of batteries. These design drivers enforced specific hardware components which, however, resulted in undesired behavior during integration and testing. In particular low-speed devices on the bus were suppressing the performance of the CDHS and the high-speed systems of Delfi-C3. Delfi-n3Xt requires a higher performance since much more data will be produced by the five payloads, stored and sent down with a high-speed downlink. The architecture presented in this paper complies with this, while it is based on the architecture of Delfi-C3.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:4a890354-578c-4e7d-a2c3-c10c46b1bd19","http://resolver.tudelft.nl/uuid:4a890354-578c-4e7d-a2c3-c10c46b1bd19","Targeting interventions for intra-organizational IT adoption","De Groot, W.J.; Reunis, M.R.B.","","2005","","technology adoption; intra-organizational adoption; interventions","en","conference paper","IADIS","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9e805538-5ac6-4711-9a10-6c533d25a20e","http://resolver.tudelft.nl/uuid:9e805538-5ac6-4711-9a10-6c533d25a20e","BioMAV: Bio-inspired intelligence for autonomous flight","Gerke, P.K.; Langevoort, J.; Lagarde, S.; Bax, L.; Grootswagers, T.; Drenth, R.J.; Slieker, V.; Vuurpijl, L.; Haselager, P.; Sprinkhuizen-Kuyper, I.; Van Otterlo, M.; De Croon, G.C.H.E.","","2011","This paper aims to contribute to research on biologically inspired micro air vehicles in two ways: (i) it explores a novel repertoire of behavioral modules which can be controlled through ?nite state machines (FSM) and (ii) elementary movement detectors (EMD) are combined with a center/surround edge detection algorithm to yield improved edge information used for object detection. Both methods will be assessed in the context of the IMAV 2011 pylon challenge.","Micro Air Vehicle; autonomous flight; biorobotics","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:59a8ba1d-070d-4879-a048-eee208d04983","http://resolver.tudelft.nl/uuid:59a8ba1d-070d-4879-a048-eee208d04983","Formation flying within a constellation of nano-satellites the QB50 mission","Gill, E.K.A.; Sundaramoorthy, P.; Bouwmeester, J.; Zandbergen, B.; Reinhard, R.","","2010","QB50 is a mission establishing an international network of 50 nano-satellites for multi-point, in-situ measurements in the lower thermosphere and re-entry research. As part of the QB50 mission, the Delft University of Technology intends to contribute two nano-satellites both being equipped with a highly miniaturized propulsion system in addition to the science payload. This allows to demonstrate formation flying between these two nano-satellites which will enhance the mission both with respect to technology demonstration and science return. The opportunities and challenges of formation flying by a subset of satellites within a constellation of freely floating spacecraft are systematically identified and analyzed.","formation flying; CubeSat; propulsion; distributed systems","en","conference paper","International Astronautical Federation","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:82a736f6-c4fa-467a-a6f1-78b88620962b","http://resolver.tudelft.nl/uuid:82a736f6-c4fa-467a-a6f1-78b88620962b","Analysis of complex inflatable structures using a multi-body dynamics approach","Breukels, J.; Ockels, W.J.","","2008","This paper outlines a simulation of inflatable structures through the use of multi-body dynamics. Beams are approximated by rigid elements, connected by spherical joints and 3-dimensional torque vectors. The stiffness of the torque vector determines the bending behavior of the beam. The stiffness is a variable stiffness with deflection. It is dependent on internal pressure and beam radius. By varying the stiffness of the torsion springs, the nonlinear behavior of an inflatable structure can be simulated. Functions for the stiffness of the torsion springs are obtained by matching to existing measured data. The simulation uses these functions to simulate more complex structures.","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:9c8d20f8-f350-49ab-ad24-3642d04062b7","http://resolver.tudelft.nl/uuid:9c8d20f8-f350-49ab-ad24-3642d04062b7","Accelerating MRO procedures for composite materials using innovative detection techniques","Boer, R.J.; Pelt, M.; Schoemaker, C.; Borst, M.; Groves, R.M.","","2015","The development of large commercial aircraft such as the Airbus A350 and the Boeing 787, together with military aircraft such as the Lockheed Martin F35, with a large share of composite components of up to 50%, make it necessary for attention to be focussed on the development of new and effective maintenance strategies. In this paper, we address the development of ultrasonic measurement techniques, with a focus on structural health monitoring (SHM) techniques that are able to quickly inspect large structural parts of the aircraft. The combination of real-time SHM techniques, together with the parallel development of automated repair techniques for bonded structures, will make it possible to operate the aircraft at lower costs and for longer periods of time, thereby increasing the economic life of these aircraft structures.","","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:185b29bc-da3b-42a2-bf83-25217fd91132","http://resolver.tudelft.nl/uuid:185b29bc-da3b-42a2-bf83-25217fd91132","Geometry effect of isolated roughness on boundary layer transition investigated by tomographic PIV","Ye, Q.; Schrijer, F.F.J.; Scarano, F.","","2015","Transitional flow over isolated roughness elements is investigated in the incompressible flow regime using Tomographic PIV. Three different geometries are considered (micro-ramp, cylinder and square) with same height and span. Their effect on accelerating boundary layer transition is compared and discussed. The measurement domain encompasses the full transition process and the flow development until the turbulent regime is established. The mean flow topology reveals a single pair of streamwise vortices for the micro-ramp as opposed to the additional pair associated to the horseshoe vortex around cylindrical and square elements. The statistical analysis of velocity fluctuations indicates a transition process induced from the point where the streamwise vortices induce an inflexional velocity profile. The cascade progresses downstream with a localized fluctuations increase at the turbulent-non-turbulent interface. The instantaneous flow topology contributes in explaining the transition mechanism, which appears to be dominated by hairpin-like vortices concentrating at the laminar-turbulent interface.","","en","conference paper","University of Melbourne","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:990f305c-5198-45ff-9f5e-2b166e08b1c0","http://resolver.tudelft.nl/uuid:990f305c-5198-45ff-9f5e-2b166e08b1c0","Tethered ""kiteplane"" design for the Laddermill project","Breukels, J.; Ockels, W.","","2005","The Laddermill is an innovative concept for generating energy from wind using large kite-like wings on a tether. The wings are able to fly in both the regime of airplanes and kites. We therefore call these structures ""kiteplanes"". By providing a recurring motion with a large lift during ascending and a lower lift during descending, energy can be generated. The Laddermill is currently under development at the Faculty of Aerospace Engineering at the Delft University of Technology. This paper presents the design and testing of a 3 meter span scaled model of a laddermill kiteplane. First, an introduction to the laddermill will be given. Then the sail wing will be outlined. Both aerodynamic and structural aspects will be addressed. The next section deals with the stability of the kiteplane. The eigenvalues are determined which govern the motions of the kiteplane. After the theory, the paper will go into the building of the kiteplane and the flight testing. The conclusion will go into the relevance of this wing concept to the laddermill and the eventual generation of sustainable energy.","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:43b808eb-c6a8-4914-b14e-95e71143b5c5","http://resolver.tudelft.nl/uuid:43b808eb-c6a8-4914-b14e-95e71143b5c5","Jupiter Icy Moons Explorer (JUICE): Science Objectives, Mission and Instruments (abstract)","Gurvits, L.; Plaut, J.J.; Barabash, S.; Bruzzone, L.; Dougherty, M.; Erd, C.; Fletcher, L.; Gladstone, R.; Grasset, O.; Hartogh, P.; Hussmann, H.; Iess, L.; Jaumann, R.; Langevin, Y.; Palumbo, P.; Piccioni, G.; Titov, D.; Wahlund, J.E.","","2014","The JUpiter ICy Moons Explorer (JUICE) is a European Space Agency mission that will fly by and observe the Galilean satellites Europa, Ganymede and Callisto, characterize the Jovian system in a lengthy Jupiter-orbit phase, and ultimately orbit Ganymede for in-depth studies of habitability, evolution and the local environment [1].","","en","conference paper","USRA","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:d061e0c8-99cd-419e-be44-225fe063f84c","http://resolver.tudelft.nl/uuid:d061e0c8-99cd-419e-be44-225fe063f84c","Characterizing Network Architecture for Inter-satellite Communication and Relative Navigation in Precise Formation Flying","Sun, R.; Guo, J.; Gill, E.K.A.; Maessen, D.","","2011","Precise formation flying (PFF) missions require formation acquisition and maintenance through interactions among spacecraft by inter-satellite communication and relative navigation. That requires the network architecture to satisfy dedicated system constraints of time-criticality for updating navigation measurements and flexibility for implementation across various phases of mission operations. Potentially applicable architectures that combine different multiple access technologies, half-duplex/full duplex configurations, and network topologies are discussed and evaluated. Half-duplex CDMA with roles rotating among all spacecraft is shown more suitable and efficient for PFF missions. Its limitation in terms of multiple access interference is analyzed as well.","precise formation flying; communication; relative navigation; time-critical; various mission phases; CDMA","en","conference paper","IARIA","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:da1014eb-4425-4902-a4e6-c3882c5c056c","http://resolver.tudelft.nl/uuid:da1014eb-4425-4902-a4e6-c3882c5c056c","On the stability of loose and strong partitioned algorithms for thermal coupling of domains using higher order implicit time integation schemes","Kazemi Kamyab, V.; Van Zuijlen, A.H.; Bijl, H.","","2012","Thermal interaction of fluids and solids, or conjugate heat transfer (CHT), is encountered in many engineering applications. Since time-accurate computations of such coupled problems can be computationally expensive, we consider loosely-coupled and strongly- coupled solution algorithms in which higher order multi-stage Runge-Kutta schemes are employed for time integration. The higher order time integration schemes have the potential to improve the computational efficiency at arriving at a certain accuracy relative to the traditionally used 1st and 2nd order implicit schemes. The spatial coupling between the subdomains is realized using Dirichlet-Neumann interface conditions and the coupled domains are solved in a sequential manner at each stage (Block Gauss-Seidel). In this paper, the stability of two partitioned algorithms is analyzed by considering a one dimensional model problem. The model problem consists of two thermally coupled domains where the governing equation within each subdomain is unsteady linear heat conduction. In the loosely-coupled approach, a family of multi-stage IMEX schemes is used for time integration. By observing similarities between the second stage of the IMEX schemes and the ? scheme with ? = 0.5 (Crank-Nicolson), the stability of the partitioned algorithm in which the Crank-Nicolson scheme is used for time integration is first analyzed by applying the stability theory of Godunov-Ryabenkii. The stability of the IMEX schemes is next investigated by numerically solving the model problem and comparing the results to the conclusions of the stability analysis for the Crank-Nicolson scheme. Due to partly explicit nature of the IMEX schemes, the loosely-coupled algorithm becomes unstable for sufficiently large Fourier numbers (similar to the Crank-Nicolson scheme). When the ratio of the thermal effusivities of the coupled domains is much smaller than unity, time step restriction due to stability is sufficiently weak that computations can be performed with reasonably large Fourier numbers. Furthermore, the results show better stability properties of the IMEX schemes compared to the Crank-Nicolson scheme. In the strongly-coupled approach, the stability and rate of convergence of performing (Gauss-Seidel) subiterations at each stage of the higher order implicit ESDIRK time integration schemes are analyzed. From the stability analysis, an expression for the rate of convergence of the iterations (?) is obtained. For cases where ? ? 1, subiterations will convergence rapidly. However, when ? ? 1, the convergence rate of the iterations is slow. The results obtained by solving the model problem numerically are in line with the performed analytical stability analysis.","high order implicit time integratio; conjugate heat; partitioned algorithm; stability","en","conference paper","","","","","","","","","Aerospace Engineering","Aerdynamics, Wind Energy and Propulsion","","","",""
"uuid:f2c44a11-f9f9-4caf-9a71-5ee70637b6af","http://resolver.tudelft.nl/uuid:f2c44a11-f9f9-4caf-9a71-5ee70637b6af","Improving the GNSS attitude ambiguity success rate with the multivariate constrained LAMBDA method","Giorgi, G.; Teunissen, P.J.G.; Verhagen, S.; Buist, P.J.","","2009","GNSS Attitude Determination is a valuable technique for the estimation of platform orientation. To achieve high accuracies on the angular estimations, the GNSS carrier phase data has to be used. These data are known to be affected by integer ambiguities, which must be correctly resolved in order to exploit the higher precision of the phase observables with respect to the GNSS code data. For a set of GNSS antennae rigidly mounted on a platform, a number of nonlinear geometrical constraints can be exploited for the purpose of strengthening the underlying observation model and subsequently improving the capacity of fixing the correct set of integer ambiguities. A multivariate constrained version of the LAMBDA method is presented and tested here.","","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:7da894fe-6b3d-49b9-a69b-9c66d392b5f9","http://resolver.tudelft.nl/uuid:7da894fe-6b3d-49b9-a69b-9c66d392b5f9","A PhD student’s experience with open research data","Pascoe, J.A.","","2014","","open access; international open access week; 3TU Datacentrum; open research data; open data experiences; sharing open data; TU Delft","en","conference paper","TU Delft Library","","","","","","","","Aerospace Engineering","","","","",""
"uuid:38ba9f1d-3995-4ac9-abad-9981e059a943","http://resolver.tudelft.nl/uuid:38ba9f1d-3995-4ac9-abad-9981e059a943","On the aeroacoustic properties of a beveled plate","Van der Velden, W.C.P.; Van Zuijlen, A.H.; De Jong, A.T.; Bijl, H.","","2015","The flow around a beveled flat plate model with an asymmetric 25 degrees trailing edge with three rounding radii is analyzed using a Navier-Stokes based open source software package OpenFOAM in order to predict the aeroacoustic properties of the models. A Large Eddy Simulation with a dynamic Smagorinsky and implicit model are used as closure model for the flow solver, and are compared regarding their aeroacoustic performance. Velocity coherence and pressure correlation is determined in spanwise direction. The acoustic far field spectrum is obtained by solving Curle’s analogy in frequency domain as a post-processing step.","","en","conference paper","EDP Sciences","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:233efda9-d2e2-4154-a311-75f27d14e7b7","http://resolver.tudelft.nl/uuid:233efda9-d2e2-4154-a311-75f27d14e7b7","Simultaneous optical and electrochemical monitoring of the protective effect of functional surface healing agents","Mathis, C.; Garcia Espallargas, S.J.","","2013","Encapsulation of reactive agents embedded within a matrix is the most studied concept to develop self-healing materials. The most common approaches employ either a single component with catalyst dispersed in the matrix or a single environment-reactive component for corrosion protection [1]. Recently an approach for corrosion protection based on a single reactive healing agent that combines wetting, reactivity with ambient humidity and the underlying metallic surface, hydrophobicity and densification in time was proposed [2]. Following this idea of using silyl esters, Huang et al. developed a similar system where 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS) was used in place of a silyl ester [3]. Despite the good results offered by the octyldimethylsilyl ester and the POTS, there is room for improvement in the design of the healing agents employed for corrosion protection. The goal of this research is to better understand the wetting, barrier and densification properties of silane based healing agents to be able to develop efficient single reactive healing agents. Therefore a selection of silanes with different chemical backbone structure and surface-reactive end group is evaluated. The barrier properties and the hydrophobicity of the agents is investigated to gain insight into the relationship between chemical structure and final thin film properties. Moreover, in order to evaluate the time dependent corrosion protection performance of the different healing agents a novel optical-electrochemical analysis technique has been developed.","corrosion protection; capsules; coating; silane; hydrophobicity; optical analysis","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:f17280e8-188c-42cb-9d57-a8239a46b93a","http://resolver.tudelft.nl/uuid:f17280e8-188c-42cb-9d57-a8239a46b93a","Buckling Analysis of Grid-Stiffened Composite Shells","Wang, D.; Abdalla, M.M.","","2014","There is a renewed interest in grid-stiffened composite structures; they are not only competitive with conventional stiffened constructions and sandwich shells in terms of weight but also enjoy superior damage tolerance properties. In this paper, both global and local structural instabilities are investigated for grid-stiffened composite panels using homogenization theory. Characteristic cell configurations with periodic boundary constraints are employed for orthogrid- and isogrid-stiffened shells in order to smear the stiffened panel into an equivalent unstiffened shell. Homogenized properties corresponding to classical lamination theory are obtained by matching the strain energy of the stiffened and equivalent cells. Global buckling analysis is carried out based on the homogenized shell properties. Bloch wave theory is adopted to calculate the local buckling load of grid-stiffened shells, where the interaction of adjacent cells is fully taken into account. Moreover, instead of considering skin buckling and stiffener crippling separately, as is commonly done, the skin and stiffeners are assembled together at the level of the characteristic cell. The critical instabilities can be captured whether they are related to the skin or stiffener or their interaction. The proposed combination of global/local models can also be used to predict the material failure of a structure. Numerical examples of orthogrid- and isogrid-stiffened isotropic panels show that the local buckling loads predicted by the proposed method match finite element calculations better than semi-analytical methods based on assumptions and idealisations. The proposed method is further validated using typical configurations of flat composite panels and circular composite cylinders.","buckling; grid-stiffened structures; composite; homogenization techniques; Bloch wave theory","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:ce470f6e-3f15-42dc-9426-be8bd5d2dcd3","http://resolver.tudelft.nl/uuid:ce470f6e-3f15-42dc-9426-be8bd5d2dcd3","Concurrent Engineering in student course Practice Space Systems Engineering","Guo, J.; Matthysen, A.; Fijneman, M.","","2014","","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:eca0feed-2e1b-487b-ae4d-ade794cacd8b","http://resolver.tudelft.nl/uuid:eca0feed-2e1b-487b-ae4d-ade794cacd8b","Medium-distance GPS ambiguity resolution with controlled failure rate","Odijk, D.; Verhagen, S.; Teunissen, P.J.G.","","2009","The goal of Network RTK is to provide users with precise ionospheric corrections in order to conduct fast GPS ambiguity resolution and to get cm-level positioning results over medium-distance baselines. In this paper it is shown that a Network RTK user should apply the ratio test with fixed failure rate, having a threshold value that depends on the model at hand, as to test whether the estimated integer solution can be accepted with sufficient more likelihood than the second-best integer solution. Application of the traditional ratio test (with a fixed threshold value) may namely result in too many wrong fixes and consequently severe positioning errors. However, in the paper it is also demonstrated that the ratio test with fixed failure rate should be applied with care, since its correct performance depends on the correctness of the underlying model.","","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:7e28f6dc-ba88-4329-823f-73827471efae","http://resolver.tudelft.nl/uuid:7e28f6dc-ba88-4329-823f-73827471efae","Trimmed simulation of a transport aircraft using fluid-structure coupling","Michler, A.K.; Dwight, R.P.; Heinrich, R.","","2009","The accurate prediction of the aerodynamic coefficients under cruise conditions is of major importance for assessing the aircraft’s fuel consumption. To this end, fluid dynamics, structural mechanics and flight mechanics have to be considered: on the one hand, the structure elastically deforms under the influence of the flow and a state of static aeroelastic equilibrium is reached; on the other hand, the aircraft’s loads are balanced by adjusting control surfaces, which influences the flow. A procedure has been developed to account for this interplay. For the interaction between fluid and structure (FSI), a partitioned approach is followed to make use of highly-specialized solvers for each discipline: for the equations governing the flow, the hybrid RANS DLR-TAU-code is employed, whereas for the structural equations, ANSYS is used. The trimmed states are computed using a Newton method, in which the derivatives are calculated using finite difference approximations or, alternatively, using the discrete adjoint. The first test case shows the trim results for a 2-dimensional wing-tail configuration, comparing the approach using finite difference approximations with the one using the discrete adjoint. The second test case uses finite differences for finding the trimmed state for the DLR-F12 transport aircraft configuration in viscous flow, comparing the results of a rigid aircraft with the ones where the wing was allowed to deform elastically.","fluid-structure interaction; partitioned approach; trim procedure","en","conference paper","International Center for Numerical Methods in Engineering (CIMNE)","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:64c569c3-b8c5-4a34-be4a-5c52e7db8501","http://resolver.tudelft.nl/uuid:64c569c3-b8c5-4a34-be4a-5c52e7db8501","Experimental and numerical study of an autonomous flap","Bernhammer, L.O.; Navalkar, S.T.; Sodja, J.; De Breuker, R.; Karpel, M.","","2015","This paper presents the experimental and numerical study of an autonomous load alleviation concept using trailing edge flaps. The flaps are autonomous units, which for instance can be used for gust load alleviation. The unit is self-powered and self-actuated through trailing edge tabs which are mounted as aerodynamic control devices on free-floating flaps. The flaps are mass underbalanced such that flutter occurs in the operational envelope unless it is suppressed by the control system. Therefore the system is very responsive to both external excitation and control activity of the trailing edge tab. The electrical energy for control activities is then generated by maintaining the flap in controlled limit cycle oscillations. The numerical simulation of such an autonomous flap system demonstrates the ability of controlling the amplitude of limit cycle oscillations, while a net gain in power can be used to charge the battery. These results are compared to experimental results obtained by a wind tunnel study of the said system.","autonomous free-floating flap; aeroelastic instability; limit cycle oscillation","en","conference paper","IFASD","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:64f0f8ca-03b5-47ed-8bf8-04491d39fad3","http://resolver.tudelft.nl/uuid:64f0f8ca-03b5-47ed-8bf8-04491d39fad3","Multigrid for High-Dimensional Elliptic Equations","Bin Zubair, H.; Oosterlee, C.W.","","2006","This paper discusses multigrid for high dimensional partial differential equations (PDEs). We present partial grid-coarsening strategies for excellent multigrid convergence in the context of elliptic PDEs. We show that the multigrid convergence rate can satisfactorily be brought down with the grid strategies proposed herein, coupled with weighted point smoothing schemes. A computer implementation of local Fourier smoothing analysis is employed to compute the optimal relaxation parameters for w-RB Jacobi in a d-dimensional setting. The use of these relaxation parameters in the smoothing process, improves convergence in higher d. We support this by the numerical experiments in the last section, demonstrating the convergence results that we get with this proposal. Multigrid ranks among one of the best known methods for the numerical solution of partial differential equations mapped to a discrete grid [1]. Problems in applied sciences, -stemming from physical systems dependent on a number of independent variables- are nowadays sometimes modelled by high dimensional partial differential equations [2,3]. This growth in the dimensionality of the problem renders many efficient algorithms impractical due to the asymptotic rise in the number of unknowns. A way around this so-called ""curse of dimensionality"" is the sparse grid technique. Sparse grids are always non-equidistant emphasizing the need of efficient solution methods for non-equidistant grids and this is the precise avenue where our present contribution fits in. We demonstrate (in numbers) the nice convergence that we get with these methods, for a general d-dimensional elliptic equation.","high-dimensions; d-multigrid; coarsening-strategies; point-smoothing","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f2c9aad2-9017-413f-9b82-5bdbb6afa499","http://resolver.tudelft.nl/uuid:f2c9aad2-9017-413f-9b82-5bdbb6afa499","Searching for extraterrestrial intelligence with the square kilometre array","Siemion, A.P.V.; Benford, J.; Cheng-Jin, J.; Chennamangalam, J.; Cordes, J.; Falcke, H.; Garrington, S.; Garrett, M.; Gurvits, L.I.; Hoare, M.; Korpela, E.; Lazio, J.; Messerschmitt, D.; Morrison, I.; O'Brien, T.; Paragi, Z.; Penny, A.; Spitler, L.; Tarter, J.; Werthimer, D.","","2014","","","en","conference paper","POS","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:dfc4ab72-9c40-4597-a4c1-5a11b134551e","http://resolver.tudelft.nl/uuid:dfc4ab72-9c40-4597-a4c1-5a11b134551e","Modeling of Optimal Power Generation using Multiple Kites","Williams, P.; Lansdorp, B.; Ockels, W.J.","","2008","Kite systems have the potential to revolutionize energy generation. Large scale systems are envisioned that can fly autonomously in “power generation” cycles which drive a ground-based generator. In order for such systems to produce power efficiently, good models of the system are required. This paper focuses on the development of optimal open-loop trajectories for kite systems. In large-scale power generation, multiple kites connected along the same line will be able to produce significantly higher power due to the increase in the line tension. The equations of motion for a multikite power generating system are derived that take into account the key system parameters. Two different configurations are modeled: all kites are connected to the same line, multiple kites are connected to branches in the cable. The model can be used to estimate the power generation capabilities of various systems through dynamic optimization studies.","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:21582883-d3fa-4d38-a4e0-0d1ae9e11d21","http://resolver.tudelft.nl/uuid:21582883-d3fa-4d38-a4e0-0d1ae9e11d21","Comparison of the conservative and a consistent approach for the coupling of non-matching meshes","De Boer, A.; Van Zuijlen, A.H.; Bijl, H.","","2006","In fluid-structure interaction simulations the meshes at the fluid-structure interface usually do not match, because of the different mesh requirements for the flow and structure. The exchange of data over the discrete interface becomes then far from trivial. In this paper we investigate the difference in accuracy and efficiency between a conservative and a consistent coupling approach. This is done for an analytical test problem as well as a quasi-1D FSI problem, for different coupling methods found in literature. It is found that when the coupling method is based on a weak formulation of the coupling conditions the conservative approach is the best choice. For other coupling methods the consistent approach provides the best accuracy and efficiency, because the conservative approach results in unphysical oscillations in the pressure received by the structure and is therefore not consistent.","fluid-structure interaction; partitioned coupling; non-matching meshes; coupling schemes","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6a3d2adc-71bf-4869-ab28-5eceb9f9abc6","http://resolver.tudelft.nl/uuid:6a3d2adc-71bf-4869-ab28-5eceb9f9abc6","A student project as part of an MSc curriculum: Delfi-C³","Vaartjes, A.A.; Hamann, R.J.","","2008","The Delfi-C3 is a university satellite of the Delft University of Technology. The project started in November 2004 and had a dual mission: (no bullets in abstract!)To offer at least 25 students as part of their Master of Science (MSc) study the opportunity to gain hands on experience on a real space project and to provide a platform for fast and low-cost technology qualification in space. The project was aiming for a launch in the first half of 2007. It was set up two faculties of Delft University of Technology in cooperation with industry partners. With over 60 students that worked on the project and a launch in April 2008, it can, already now, be concluded that the project was a success. The paper addresses lessons-learned from Delfi-C3 related to thesis supervision, hierarchy in the project and workforce discontinuity. Also from the side of the university some adaptations are required to enable an efficient, effective and qualitatively satisfactory execution of the project. These adaptations are related to the type of staff required, composition of the student team and, generally, “production-process-mindedness” of supporting university departments. And, may be most important, the student’s effort as a team member must be valued such that he or she may achieve the same appreciation as his or her fellow students working on an individual, theoretical MSc thesis subject.","space development project; Master thesis; lessons learned","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:e2964da2-a681-43cc-bc83-33d9a196f2d9","http://resolver.tudelft.nl/uuid:e2964da2-a681-43cc-bc83-33d9a196f2d9","Model comparison for angle droplet fragmentation under varying accelerations","Bartz, F.O.; Guildenbecher, D.R.; Schmehl, R.; Koch, R.; Bauer, H.J.; Sojka, P.E.","","2011","Different models for single droplet fragmentation have been assessed for different initial accelerations in the bag and sheet-thinning regimes. The predictions have been compared to high-speed-video sequences where a single droplet is injected in a cross-flow of air. It is concluded that the modeling of the temporal evolution of the breakup process is important. This includes modeling of the droplet drag before and after droplet initiation as well as a realistic breakup time. Furthermore, if the breakup criterion is based on a critical deformation instead of a critical Weber number, predictions of trajectories are improved for transient aerodynamic loadings.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:cfe53d77-3642-48b3-a827-c2a485433af1","http://resolver.tudelft.nl/uuid:cfe53d77-3642-48b3-a827-c2a485433af1","Base Flow Investigation of the Apollo Command Module in the Frame of AVT-136","Walpot, L.M.G.; Noeding, P.; Schrijer, F.F.J.; Wright, M.J.","","2010","The current uncertainty levels for afterbody (base) aeroheating are very large for capsule like (re)entry vehicles. The design margin on missions have traditionally ranged up to 200% of CFD predictions. These uncertainties can be attributed to a lack of validation of the CFD tools with suitable flight data and a general difficulty in simulating afterbody flow fields in ground facilities in which base flows are perturbed by sting effects. In addition to basic smooth wall afterbody properties, local disturbances, e.g. connectors, windows and RCS thruster/flowfield interactions have to be taken into account for design. Without an established confidence in the ability of CFD to predict the base flowfield, any attempt to predict the latter effects would be futile. Within RTO AVT-136 / RTG-043 a task group has been created to investigate base flows of the AS-202. The AS-202 was one the four full-scale Apollo flight tests in 1966 at super-orbital entry speeds (in excess of 9 km/s), prior to manned missions. This paper deals with the CFD analysis of the hot hypersonic AS-202 flight and supersonic tests of a scaled AS-202 model in the TU Delft supersonic wind tunnel. CFD results of European and US structured and unstructured codes will be analyzed and compared with the AS-202 flight data and the available wind tunnel data of the TU Delft.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:5857a334-8608-45b2-a35f-ade030d163a9","http://resolver.tudelft.nl/uuid:5857a334-8608-45b2-a35f-ade030d163a9","SCALES: A System Level Tool for Conceptual Design of Nano- and Microsatellites","Aas, C.; Zandbergen, B.T.C.; Hamann, R.J.; Gill, E.K.A.","","2009","A satellite design tool has been developed offering systems engineers a fast way to analyze the feasibility of a particular design concept. The tool differs from available tools on the market in that it is specifically targeted at small satellites in the mass range of 1-50 kg, and with a limited development time. The tool is developed in Excel, and users interact with the tool in an intuitive manner through only one input and one output sheet. Required inputs include payload specifications, launcher characteristics, sensor & actuator types, and goal satellite mass, volume and power level. Outputs offered by the tool include mass, volume and power budgets, operating temperature envelope, attitude accuracy, propellant mass, transmit power and data rate. Algorithms, “rules-of thumb” and estimation relationships linking the input parameters with the output parameters have been based on models found in current literature, but have been revised and redefined based on an extensive satellite database containing over 200 satellites in the mass range of 0.1 – 50 kg, developed at Delft University of Technology.","nanosatellite; microsatellite; conceptual; design tool; scaling","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:fddb7820-1e79-4744-ad38-f92b9251d02b","http://resolver.tudelft.nl/uuid:fddb7820-1e79-4744-ad38-f92b9251d02b","Comparison of concepts for high-altitude wind energy generation with ground based generator","Ockels, W.J.; Lansdorp, B.","","2005","","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2dc7f4c0-e5aa-4ae8-af6b-abe324c7373a","http://resolver.tudelft.nl/uuid:2dc7f4c0-e5aa-4ae8-af6b-abe324c7373a","Anytime, Anywhere – The development of an online course in Research Methodologies","Saunders-Smits, G.N.; Mebus, L.F.M.","","2015","","online learning; blended learning; research methodologies; OER","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:cc000297-3eec-4a81-bd5d-bfc7bf16eb14","http://resolver.tudelft.nl/uuid:cc000297-3eec-4a81-bd5d-bfc7bf16eb14","The value of firm-addressable resources for European Airports","Van de Rijt, J.; Santema, S.C.","","2005","","airports; strategy; resources","en","conference paper","IMP Group","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f0726d0b-32bc-4623-82c5-e26fb10124dd","http://resolver.tudelft.nl/uuid:f0726d0b-32bc-4623-82c5-e26fb10124dd","Next generation GNSS single receiver cycle slip reliability","Teunissen, P.J.G.; De Bakker, P.F.","","2009","In this contribution we study the multi-frequency, carrier-phase slip detection capabilities of a single receiver. Our analysis is based on an analytical expression that we present for themulti-frequencyminimal detectable carrier phase cycle slip.","GNSS cycle slips; Minimal Detectable Bias (MDB); multi-frequency receivers","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:704fe114-02d5-43ad-b94a-eb4c94696fe2","http://resolver.tudelft.nl/uuid:704fe114-02d5-43ad-b94a-eb4c94696fe2","Three-Dimensional Particle Image Velocimetry Using a Plenoptic Camera","Lynch, K.P.; Fahringer, T.; Thurow, B.","","2012","A novel 3-D, 3-C PIV technique is described, based on volume illumination and a plenoptic camera to measure a velocity field. The technique is based on plenoptic photography, which uses a dense microlens array mounted near a camera sensor to sample the spatial and angular distribution of light entering the camera. Various algorithms are then used to reconstruct a volumetric intensity field after the image is taken, and cross-correlation algorithms extract the velocity field from the reconstructed volume. This paper provides an introduction to the concepts of light fields and plenoptic photography, and describes the algorithms used to reconstruct the measurement volume. A comparison is made between the use of a combined computational refocusing and thresholding approach versus a direct tomographic reconstruction approach. This discussion lays the groundwork for a more detailed study of reconstruction accuracy, achieveable particle number density, reconstruction ambiguities (e.g., ghost particles), and other factors in a following study. Additionally, the construction of a prototype camera based on a 16-megapixel interline CCD sensor is described and preliminary experimental renderings are given.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:6d961ece-c87e-484f-bf61-7cdb2f93ffd5","http://resolver.tudelft.nl/uuid:6d961ece-c87e-484f-bf61-7cdb2f93ffd5","Semi-Analytical Weight Estimation Method for Fuselages with Oval Cross-Section","Vos, R.; Hoogreef, M.F.M.","","2013","This paper presents a semi-analytical method for the weight estimation of fuselages with an oval cross-section, applied to blended wing body aircraft. The weight estimation of the fuselage primary structure is based on a structural analysis of two-dimensional crosssections and it is completed by a set of empirical relations for the weight estimation of the secondary structure and non-structural items. A conceptual design study on a stable (5% static margin), 400-passenger blended wing body aircraft has been performed with the weight estimation method implemented in an aircraft conceptual-design program. A top level requirement for the harmonic range of 15,200km was imposed on the design. From the anaylis a maximum take-off weight of 395 metric tons has been found, with an operative empty weight fraction of 45% and a fuselage airframe weight of 47.3 metric tons (amounting to 26% of the operative empty weight). The results of this study are presented in comparison to the Boeing 777-200LR airliner, showing a slightly higher operative empty weight fraction, a lower fuel consumption of 2.05kg per passenger per 100km.","blended wing body; oval fuselage; weight estimation; class 2.5 weight estimation; semi-analytical weight estimation","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:94d252a5-dc42-43b2-8883-7f7d5c80b878","http://resolver.tudelft.nl/uuid:94d252a5-dc42-43b2-8883-7f7d5c80b878","Behavioral Interventions for Intra-Organizational Adoption of E-Procurement","Reunis, M.R.B.","","2005","","e-procurement adoption; technology adoption; behavioral intervention","en","conference paper","EIPM","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9594254e-547a-439e-a609-f6d0e6c1e2a8","http://resolver.tudelft.nl/uuid:9594254e-547a-439e-a609-f6d0e6c1e2a8","Opportunities and challenges of wireless sensor networks in space","Sun, R.; Guo, J.; Gill, E.K.A.","","2010","Challenges and opportunities of wireless sensor networks (WSNs) in space applications are presented. The investigation of internet protocols, ad hoc routing and commercial-off-the-shelf (COTS) wireless communication protocols for efficient and reliable network design is addressed. In order to facilitate the analysis, several application scenarios of space-based WSNs are given, including autonomous formation flying, very-small-satellite cluster/swarm, fractionated spacecraft, onboard sensor network and surface vehicles for planetary exploration. Criteria that contain network scale, link range, degree of dynamics, data rate, power consumption, time intensive requirement, and degree of cooperation are proposed in order to classify applications and choose the most potentially applicable technologies. Different levels of challenges to implement each application are also compared.","","en","conference paper","International Astronautical Federation","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:dd1c4167-8c32-4cf1-b087-ba91608ca9a6","http://resolver.tudelft.nl/uuid:dd1c4167-8c32-4cf1-b087-ba91608ca9a6","Flexible Tethered Kite with Moveable Attachment Points, Part II: State and Wind Estimation","Williams, P.; Lansdorp, B.; Ockels, W.","","2007","","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9a1e402f-af91-429b-92dd-a631e9da56ca","http://resolver.tudelft.nl/uuid:9a1e402f-af91-429b-92dd-a631e9da56ca","Lamb wave dispersion time-domain study using a combined signal processing approach","Ochoa, P.; Groves, R.M.; Benedictus, R.","","2015","Ultrasonic Lamb wave techniques are described as one of the most encouraging developments for structural health monitoring of aerospace composite structures. The reliability of those techniques is highly dependent on the quality of signal processing algorithms capable of extracting useful information out of complex responses. When damage localization is involved, it is crucial to rigorously determine time-of-flight (TOF) of wave groups. Among the available methods for automated TOF extraction the Akaike Information Criterion (AIC) and the Hilbert Transform (HT) have become very popular. The first one detects the onsettime of a signal based on the minimization of the AIC function. The second one relies on the HT to define the response envelope, allowing maximum amplitude points to be used for time interval measurement. This paper focuses primarily on comparing the aforementioned methods in order to assess their reliability for TOF determination. Additionally, a combined AIC-HT approach is used to further quantify Lamb wave dispersion phenomena.","","en","conference paper","Vrije Universiteit Brussel","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:bbd2f0e4-f073-4286-89c7-b50774d3a810","http://resolver.tudelft.nl/uuid:bbd2f0e4-f073-4286-89c7-b50774d3a810","Vehicle detection from an image sequence collected by a hovering helicopter","Karimi Nejadasl, F.; Lindenbergh, R.C.","","2011","This paper addresses the problem of vehicle detection from an image sequence in difficult cases. Difficulties are notably caused by relatively small vehicles, vehicles that appear with low contrast or vehicles that drive at low speed. The image sequence considered here is recorded by a hovering helicopter and was stabilized prior to the vehicle detection step considered here. A practical algorithm is designed and implemented for this purpose of vehicle detection. Each pixel is identified firstly as either a background (road) or a foreground (vehicle) pixel by analyzing its gray-level temporal profile in a sequential way. Secondly, a vehicle is identified as a cluster of foreground pixels. The results of this new method are demonstrated on a test image-sequence featuring very congested traffic but also smoothly flowing traffic. It is shown that for both traffic situations the method is able to successfully detect low contrast, small size and low speed vehicles.","foreground and background identification; vehicle detection; temporal profile; sequential method; maximum frequency","en","conference paper","International Society for Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:8b6cbff5-0806-4ca0-b170-e1c07a52e22a","http://resolver.tudelft.nl/uuid:8b6cbff5-0806-4ca0-b170-e1c07a52e22a","Performance comparison of microprocessors for space-based navigation applications","De Florio, S.; Gill, E.K.A.; D'Amico, S.; Grillenberger, A.","","2009","","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:17978957-4684-4a02-bc88-5c22254796da","http://resolver.tudelft.nl/uuid:17978957-4684-4a02-bc88-5c22254796da","The Influences of Overlap Length, Bond Line Thickness and Pretreatmant on the Mechanical Properties of Adhesives: Focussing on Bonding Glass","Vervloed, J.; Kwakernaak, A.; Poulis, H.","","2008","This paper focuses on the influences of overlap length, bond line thickness and pretreatment on the mechanical properties of adhesive bonds. In order to determine the bond strength, lap shear tests were performed. The researched adhesives are a 2 component epoxy and MS polymer. The smallest overlap length of the epoxy adhesive results in the highest maximum bond stress. However, there is nosignificant difference in maximum bond stresses due to different overlap lengths of the MS polymer. When the bond line thickness of the MS polymer is increased, the maximum stress of the adhesive bond decreases considerably. In addition of these tests some examples of our experience in bonding glass are presented.","","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Adhesion Institute","","","",""
"uuid:286940aa-e128-4b63-97ff-1adadff40b98","http://resolver.tudelft.nl/uuid:286940aa-e128-4b63-97ff-1adadff40b98","Towards Certifiable Advanced Flight Control Systems, A Sensor Based Backstepping Approach","Falkena, W.; Van Oort, E.R.; Chu, Q.P.","","2011","This paper uses singular perturbation theory in order to design a backstepping control system. Earlier applications using singular perturbation theory for control of non-affine systems exist, but here the focus is shifted to uncertain systems. Dealing with uncertainties in this way could be a major benefit for certification of advanced control laws. The reason for this is twofold. First, the backstepping construct, using Lyapunov functions, guarantees the stability of the controlled system. Second, by using measurements of the state derivatives rather than relying on perfect knowledge of the system, a major drawback of backstepping is removed: the need for adaptation to uncertain parameters or unknown model structure. As this method bears resemblance to sensor based nonlinear dynamic inversion, the control law developed in this paper will be referred to as sensor based backstepping. Preliminary results for systems with uncertainty and sensor noise look very promising and future investigation into the effects of time-delays is needed.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:876637b7-e637-4d51-95ea-702c4d8f1962","http://resolver.tudelft.nl/uuid:876637b7-e637-4d51-95ea-702c4d8f1962","Effect on a shock wave boundary layer interaction of air jet vortex generators","Souverein, L.J.; Debieve, J.F.","","2013","The effect of upstream injection by means of continuous Air Jet Vortex Generators (AJVGs) on a shock wave turbulent boundary layer interaction is experimentally investigated. The baseline interaction is of the impinging type, with a flow deflection angle of 9.5?, a Mach number Me = 2.3, and a momentum thickness based Reynolds number of 5,000. Considered are the effects of the AJVGs on the upstream boundary layer flow topology and on the spatial and dynamical characteristics of the interaction. To this aim, Stereoscopic Particle Image Velocimetry has been employed, in addition to hot-wire anemometry (HWA) for the investigation of the dynamical characteristics of the reflected shock. It is shown that the AJVGs significantly modify the three-dimensionality of the upstream boundary layer. Overall, the AJVGs cause a reduction of the separation bubble length and height. In addition, the energetic frequency range of the reflected shock is increased by approximately 50%, which is in qualitative agreement with the smaller separation bubble size.","","en","conference paper","EDP Sciences","","","","","","","","Aerospace Engineering","Aerospace Design, Integration & Operations","","","",""
"uuid:c20e9039-7dbb-4596-8712-c7d00bfc3f56","http://resolver.tudelft.nl/uuid:c20e9039-7dbb-4596-8712-c7d00bfc3f56","Continuous Aerodynamic Modelling of Entry Shapes","Dirkx, D.; Mooij, E.","","2011","During the conceptual design phase of a re-entry vehicle, the vehicle shape can be varied and its impact on performance evaluated. To this end, the continuous modeling of the aerodynamic characteristics as a function of the shape is useful in exploring the full design space. Local inclination methods for aerodynamic analysis have proven sufficiently accurate for use at such a design stage, but manual selection of methods over the vehicle is inefficient for the exploration of a large number of design possibilities. This paper describes the model of an aerodynamic analysis code, written for use in conceptual vehicle shape optimization, which includes an automatic method selection algorithm. Panel shielding is also included in the analysis code to allow for the analysis of more complex geometries. The models used for the shape and aerodynamics are described and results for the Space Shuttle and Apollo are compared to wind tunnel data. They show an accuracy of better than 15% for most cases, which is sufficient for the use in conceptual design. Panel shielding is shown to be important in the prediction of control derivatives at low angle of attack, as well as the prediction of lateral stability derivatives. Finally, a simple guidance algorithm is used to assess the impact of the errors in the aerodynamic coefficients on the vehicle heat load and ground track length. Both show discrepancies of less than 10%.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:c9ee7444-d407-4c49-8ddb-f824ca4dc064","http://resolver.tudelft.nl/uuid:c9ee7444-d407-4c49-8ddb-f824ca4dc064","Flight-path vector symbology in tunnel-in-the-sky displays","Mulder, M.","","1999","","aircraft control; cockpit displays; information analysis; cybernetics","en","conference paper","Group D Publications Ltd","","","","","","","","Aerospace Engineering","","","","",""
"uuid:70195ec0-ef1f-4225-8f0d-bf0c56b58458","http://resolver.tudelft.nl/uuid:70195ec0-ef1f-4225-8f0d-bf0c56b58458","Experimental and numerical study of radial flow and its contribution to wake development of a HAWT","Micallef, D.; Akay, B.; Sant, T.; Simao Ferreira, C.J.; Van Bussel, G.J.W.","","2011","The scope of this work was to investigate radial flow component for a Horizontal Axis Wind Turbine in axial flow conditions and to assess its impact on the turbine operation. This was done by means of Particle Image Velocimetry and numerical simulation with a 3D unsteady potential-flow panel model. A direct comparison between the numerical and experimental radial velocity results show differences in the tip and root regions. These differences have important implications on the wake development just at the moment of release of the tip vortex. Moreover, the impact of the radial velocities on the blade loading has been studied using the numerical results. The contribution of the radial velocity to the normal load on the blade is only slightly appreciable in the tip and root regions of the blade. However, as the numerical model does not account for viscous effects, further analysis of impact on boundary layer development is necessary.","horizontal axis wind-turbine; radial flow; wake expansion","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:18975345-7e9d-4566-a193-89faca7215ac","http://resolver.tudelft.nl/uuid:18975345-7e9d-4566-a193-89faca7215ac","Suppression of classical flutter using a 'smart blade'","Politakis, G.; Haans, W.; Van Bussel, G.J.W.","","2008","","","en","conference paper","American Institute of Aeronautics and Astronautics AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:892bb0ab-3f0d-4c12-a9af-0d4f30a00d33","http://resolver.tudelft.nl/uuid:892bb0ab-3f0d-4c12-a9af-0d4f30a00d33","Virtual space academy","Gill, E.K.A.; Lisi, M.; Bousquet, M.; Larson, W.J.","","2008","The space sector needs highly trained personnel. This calls for a continuous learning process comprising post-graduate educational programs. However, the offered programs differ substantially in scope and characteristics, coverage and focus, quality and organization and lack inter-program coordination. To remedy this, a Virtual Space Academy has been initiated which allows coordination of post-graduate space education and realizes cross-fertilization between the programs to enhance and stimulate space education. The paper addresses the process of setting up the Virtual Space Academy from a European nucleus and details its objectives. The opportunities that the academy offers in providing a continuity of highly qualified space engineers and managers, maintaining a knowledge base in line with current technology standards and trends, realizing cost savings through harmonization and cooperation within the virtual setting of the academy are also addressed.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:b642024a-2298-4f4a-989c-3b827412bc1a","http://resolver.tudelft.nl/uuid:b642024a-2298-4f4a-989c-3b827412bc1a","Tuning of the lateral specific force gain based on human motion perception in the Desdemona simulator","Correia Gracio, B.J.; Van Paassen, M.M.; Mulder, M.; Wentink, M.","","2010","Generally, motion simulators present motion and visual cues different from each other due to the physical limitations of the motion platform. Nonetheless, high fidelity motion platforms are capable of simulating some maneuvers one-to-one, i.e., motion cues equal to visual cues. However, one-to-one simulation is normally not preferred by subjects and the simulator motion is reported as too strong. In this study we investigated whether this overestimation depends on the frequency and amplitude of inertial motion. The stimuli in this study consisted of translations in the lateral direction. The Desdemona research simulator was used to generate the motion profiles. Six sinusoidal profiles with different combinations of amplitude and frequency were used as reference stimuli. For every experimental condition, the visual and inertial information had equal frequency but different amplitude. Subjects had to change the inertial motion amplitude until they obtained the best relation between the two sources of motion information. Our results showed that stimuli with high amplitude were associated with smaller motion gains than stimuli with lower amplitude. The same occurred for stimuli with higher frequency when compared to stimuli with lower frequency. The findings in this study suggest that a dynamic scaling algorithm for inertial motion could improve the perceived realism of motion simulation.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:33f2cac7-4883-4043-aad3-465f8b2ad3e4","http://resolver.tudelft.nl/uuid:33f2cac7-4883-4043-aad3-465f8b2ad3e4","Level Set Method Based on Interval Analysis","De Weerdt, E.; Van Oort, E.R.; Van Kampen, E.; Chu, Q.P.","","2011","Level set methods are used to determine the reachable set for a given time domain. In the aerospace industry level set methods are used to determine for example flight envelopes. A new level set method is presented which uses interval analysis to give guaranteed bounds on the solution. Unlike the current grid-based methods the new method does not use a grid and has a lower computation complexity. The guaranteed bounds are a product of using interval analysis. Both an inner and outer bound can be derived. The time step and accuracy are easily controlled by the user and can be automatically adapted during processing. Initial tests show that the new method provides accurate solutions and does so using lower computational loads. The new method is tested on a one-dimensional and a two-dimensional test bed, showing that correct outer bounds of the reachable sets can be computed.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:b70b75c2-117e-45f9-8902-a47e8462aab2","http://resolver.tudelft.nl/uuid:b70b75c2-117e-45f9-8902-a47e8462aab2","Tracking curved trajectories with a tunnel-in-the-sky display","Mulder, M.","","1998","","aircraft control; cockpit displays; information analysis; cybernetics","en","conference paper","LAMIH","","","","","","","","Aerospace Engineering","","","","",""
"uuid:aca8c44c-6240-404a-a169-3f7695156369","http://resolver.tudelft.nl/uuid:aca8c44c-6240-404a-a169-3f7695156369","Take-off and Landing Using Ground Based Power - Landing Simulations Using Multibody Dynamics","Wu, P.; Voskuijl, M.; Van Tooren, M.J.L.","","2014","A novel take-off and landing system using ground based power is proposed in the EUFP7 project GABRIEL. The proposed system has the potential benefit to reduce aircraft weight, emissions and noise. A preliminary investigation of the feasibility of the structural design of the connection mechanism between aircraft and ground system has been performed by simulating the landing procedure on a moving ground system. One of the key challenges is the landing on a moving ground system under high crosswind conditions. The main focus in the current research is the calculation of the impact loads on both aircraft and ground system for a wide range of landing conditions (sink rate, velocity differences between aircraft and ground system, etc.). For comparison, conventional landing procedures with a traditional landing gear have also been simulated. Two different aerodynamic models (empirical and vortex lattice method) have been used and compared in the simulations for verification and validation purposes. The results of this research study are a set of load cases and operational constraints that can be used for the structural design of the ground system and modifications to the aircraft. Detailed values are presented in the paper.","multibody dynamics; aircraft landing; field performance; assisted takeoff and landing","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:8ae3eea4-fcf9-45f3-8cd9-e8f0adbef1b3","http://resolver.tudelft.nl/uuid:8ae3eea4-fcf9-45f3-8cd9-e8f0adbef1b3","Influence of Nonlinear Irregular Waves on the Fatigue Loads of an Offshore Wind Turbine","Van der Meulen, M.B.; Ashuri, T.; Van Bussel, G.J.W.; Molenaar, D.P.","","2012","In order to make offshore wind power a cost effective solution that can compete with the traditional fossil energy sources, cost reductions on the expensive offshore support structures are required. One way to achieve this, is to reduce the uncertainty in wave load calculations by using a more advanced model for wave kinematics. As offshore wind turbines are generally sited in shallow water, nonlinear effects which results in steeper waves with higher velocities and accelerations are common. Whereas extreme waves are modeled with higher-order nonlinear regular wave models, fatigue loads are calculated from kinematics obtained by a low-fidelity linear irregular wave model. In this paper, a second-order wave model that is employed to simulate the dynamic response due to nonlinear irregular waves on a full set of IEC-standard load cases. This method is computationally efficient, which is particularly useful for design optimization studies. It is shown that by using this method for a 25 m deep site in the German Bight, equivalent fatigue loads increase by 7.5 % compared to the traditional linear wave model. The effect of nonlinear waves on fatigue is most prevalent in the foundation and tower parts near the sea surface. Furthermore, it is found that the increase in fatigue damage accumulation is most prevalent in wind-wave misaligned load cases, in which aerodynamic damping is absent.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:5c2f44b9-97a1-4ee6-9ab8-b8251ee57698","http://resolver.tudelft.nl/uuid:5c2f44b9-97a1-4ee6-9ab8-b8251ee57698","Influence of temperature on strength and failure mechanisms of resistance welded thermoplastic composites joints","Koutras, N.; Fernandez Villegas, I.; Benedictus, R.","","2015","In this work, the effect of temperature exposure on the strength of resistance welded joints is analysed. Glass fibre polyphenylene sulphide (GF/PPS) laminates were joined using the resistance welding technique and a stainless steel metal mesh as the heating element. Single lap shear tests at temperatures between 20°C and 150°C were performed to evaluate the strength of the welded joints and fractography was used to investigate changes in the failure mechanisms at elevated temperatures. The results show a strength reduction of 10-15% for the samples tested at temperatures up to 90°C, and a strength reduction of 22% and 38% for the samples tested at 120°C and 150°C, respectively, while the fracture surfaces observation revealed changes in the failure mechanisms of the welded joints tested at elevated temperatures.","thermoplastic composites; resistance welding; temperature; joint strength; failure mechanism","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:a821c8b0-4a14-4e00-b9d3-cdf2b2ccf9d2","http://resolver.tudelft.nl/uuid:a821c8b0-4a14-4e00-b9d3-cdf2b2ccf9d2","Conflict detection and resolution system architecture for unmanned aerial vehicles in civil airspace","Jenie, Y.I.; van Kampen, E.J.; Ellerbroek, J.; Hoekstra, J.M.","","2015","A novel architecture for a general Unmanned Aerial Vehicle (UAV) Conflict Detection and Resolution (CD&R) system, in the context of their integration into the civilian airspace, is proposed in this paper. The architecture consists of layers of safety approaches ,each representing a combination of different methods for surveillance, coordination, action and decision. These are collected from a survey of various CD&R methods existing in both manned and unmanned domains. The combination process shows that some approaches aresuitable, while others are not, for the context of UAV integration. The suitable approachesare then arranged using the 'defense in depth' concept, where each layer filters a specific type of intruder. The final arrangement is set as the proposed architecture, and implemented in an assumed UAV operation within the civil airspace. System and infrastructure considerations are discussed for several examples of prospective types of operation in the airspace.","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:3fa1eba0-dcfc-4ca4-ac4c-572ea78738dd","http://resolver.tudelft.nl/uuid:3fa1eba0-dcfc-4ca4-ac4c-572ea78738dd","A quantitative flow visualization technique for on-site sport aerodynamics optimization","Sciacchitano, A.; Caridi, G.; Scarano, F.","","2015","Aerodynamics plays a crucial role in many speed sports, where races are often won by fractions of a second. A thorough understanding of the flow field around an athlete is of paramount importance to optimize the athletes’ posture, garment roughness and equipment shape to achieve the minimum aerodynamic drag and maximum velocity. To date, aerodynamic measurements are typically conducted in wind tunnels, using balances or pressure sensors. As a consequence, no information on the flow field responsible of the aerodynamic loads is gathered. Furthermore, the use of steady models yields a flow field that may differ significantly from that encountered during a race, where the athlete is in motion. The present paper proposes to use large-scale tomographic PIV for sport aerodynamic investigation. Helium-filled soap bubbles (HFSB) as flow tracers allow velocity measurements in a volume exceeding 10,000 cm3, from which the aerodynamic loads can be computed. The technique is suitable for conducting on-site aerodynamic measurements via the ring-of-fire concept: the measurements are carried out during the athletes’ training in a velodrome, thus reproducing the same flow conditions met during races.","","en","conference paper","Elsevier","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:43151407-c489-4c91-83bb-20a64cba0e53","http://resolver.tudelft.nl/uuid:43151407-c489-4c91-83bb-20a64cba0e53","Near-infrared optical coherence tomography for the inspection of fiber composites","Liu, P.; Yao, L.; Groves, R.M.","","2015","Optical coherence tomography (OCT) is a non-invasive imaging method, which allows the econstruction of three dimensional depth-resolved images with microscale resolution. Originally developed for biomedical diagnostics, nowadays it also shows a high potential for applications in the field of non-destructive testing (NDT). This work demonstrates how OCT could help to investigate the delamination growth in fiber composites. A customized OCT system was built with a near-infrared light source with center wavelength at 1550 nm. It was used as an inline NDT tool to monitor the crack tips and image the crack surfaces within a glass fiber composite under static loading. For carbon fiber composites, although it is difficult to acquire the internal structures due to their opaque property, OCT can still work as a surface profilometer to reconstruct 3D crack surface profiles, providing substantial information for the study of crack growth in the composites.","","en","conference paper","DGZfP","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:c96b5409-df0a-4c51-9445-a3e42734ee85","http://resolver.tudelft.nl/uuid:c96b5409-df0a-4c51-9445-a3e42734ee85","Thin layers of Cu2O on three-dimensional copper current collectors for Li-ion microbatteries (abstract)","Valvo, M.; Rehnlund, D.; Lafont, U.; Hahlin, M.; Edström, K.; Nyholm, L.","","2013","","","en","conference paper","The Electrochemical Society","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:987bc48f-13e3-4cf8-9f6b-404865b161e9","http://resolver.tudelft.nl/uuid:987bc48f-13e3-4cf8-9f6b-404865b161e9","EP Adoption and non-adoption: More than just the mirror image?","Hultman, J.; Reunis, M.R.B.; Santema, S.C.","","2005","","adoption; non-adoption; process; e-procurement","en","conference paper","EIPM","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5ac28282-2501-4c27-bf98-4b6109008160","http://resolver.tudelft.nl/uuid:5ac28282-2501-4c27-bf98-4b6109008160","Error analysis of 3D shearography using finite-element modelling","Goto, D.T.; Groves, R.M.","","2010","This paper describes the development of an opto-mechanical simulation of a complete shearography system, including the shearography instrument, the samples and the test environment. This simulation is applied to the measurement of 3D strains in engineering samples. The samples are a cylinder loaded by internal pressure and a flat plate under axial load. Finite elements models are used to obtain the displacements fields. A 3D shearography instrument consisting of a laser and four cameras has been simulated using the optical model. Combining the finite elements and optical simulations allows phase maps to be generated, which are the predictions for measurements using the complete test setup. Errors due to sample material properties, loading inaccuracy and dimensional tolerances are included in the model and this allows the calculation of phase maps at the minimum and maximum error limits. The simulation through path lengths and the simulation by inverted shearography processing provide similar results and the difference is associated with the approximation introduced by the sensitivity vector.","3D Shearography, strain measurement, finite element model, error analysis","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Optical Non-Destructive Testing Laboratory","","","",""
"uuid:845603f5-6dad-4117-99e4-c2d539cfd8a7","http://resolver.tudelft.nl/uuid:845603f5-6dad-4117-99e4-c2d539cfd8a7","A comparison of Bayesian and evidence-based fusion methods for automated building detection in aerial data","Khoshelham, K.; Nedkov, S.; Nardinocchi, C.","","2008","Automated approaches to building detection are of great importance in a number of different applications including map updating and monitoring of informal settlements. With the availability of multi-source aerial data in recent years, data fusion approaches to automated building detection have become more popular. In this paper, two data fusion methods, namely Bayesian and Dempster-Shafer, are evaluated for the detection of buildings in aerial image and laser range data, and their performances are compared. The results indicate that the Bayesian maximum likelihood method yields a higher detection rate, while the Dempster-Shafer method results in a lower false-positive rate. A comparison of the results in pixel level and object level reveals that both methods perform slightly better in object level.","fusion; building detection; automation; aerial image; laser scanning","en","conference paper","International Society for Photogrammetry and Remote Sensing","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:f8d11e3f-1210-4bdd-ba5b-bc99989c9e44","http://resolver.tudelft.nl/uuid:f8d11e3f-1210-4bdd-ba5b-bc99989c9e44","Mechanical setup for optical aperture synthesis for wide field imaging","Giesen, P.; Ouwerkerk, B.; Van Brug, H.; Van den Tool, T.; Van der Avoort, C.","","2004","Homothetic mapping is a technique that combines the images from several telescopes so that it looks like as though they came form a single large telescope. This technique enables a much wider interferometric field of image than current techniques can provide. To investigate the feasibility, a research testbed is build know as Delft Testbed interferometer (DTI). DTI simulates a configuration of three telescopes collecting light of a set of 3 stars. The stars are simulated by coupling light of a Xenon light source into three fibres, which illuminate a parabolic mirror. The light that is used has wavelengths of 500 nm - 800 nm. The light of the three telescopes will be combined in such a way that the beam arrangement in the pupil plane corresponds with the telescope arrangement and the Optical Path Difference (OPD) is minimized for the three beams. To achieve white light fringes with high visibility, the mechanical testbed that is 2 m x 1 m x 0.5 m in size, requires stable mounting of components. This paper describes the mounting of the diamond turned off-axis parabolic mirrors of 200 mm in diameter and 240 mm flat mirrors; furthermore, it describes components like the telescopes and the active controllable components for repositioning of the beam arrangement. Mechanisms were developed for alignment of piezo actuators and for delay lines. The delay lines can also be used to compensate pupil rotation. Test results demonstrate that the test setup is highly stable for temperature as well as for airflow, although the system is placed in a non-thermally controlled lab. This allows measurements of nm, in presence of ?m disturbances.","homothetic mapping; aperture synthesis; thermal stability; ajustable stable mounts; telescope; pupil reimaging","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7bc4ac3e-46d6-4113-8b47-2893ab0fe88e","http://resolver.tudelft.nl/uuid:7bc4ac3e-46d6-4113-8b47-2893ab0fe88e","Aerodynamic characteristics of wind turbine blade airfoils at high angles-of-attack","Timmer, W.A.","","2010","Airfoil characteristics at deep stall angles were investigated. It appeared that the maximum drag coefficient as a function of the airfoil upwind y/c ordinate at x/c=0.0125 can be approximated by a straight line. The lift-drag ratios in deep stall of a number of airfoils with moderate lower surface thickness coincide. It was found that the lift-drag ratio of airfoils with leading edge separation is independent of aspect ratio. The lift-drag ratios of the various sections of a non-rotating and a rotating blade in deep stall coincide with the two-dimensional curve.","airfoil characteristics; lift-todrag ratio; high angles of attack","en","conference paper","European Wind Energy Association","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:9e8e2dae-639b-4fd6-b4bd-1318b37e60c2","http://resolver.tudelft.nl/uuid:9e8e2dae-639b-4fd6-b4bd-1318b37e60c2","A multi-body dynamics approach to a cable simulator for kites","Breukels, J.; Ockels, W.J.","","2007","For the purpose of ultimately building a fully dynamic simulation of kites, an investigation is launched into a viable model of the cable with which the kite is attached to the ground. In the model proposed in this paper, only the slow modes of motion are taken into account due to the fact that only the slow motions have a real effect on the flight characteristics of the kite. Fast vibrations have a low amplitude with little effect. Also, by taking out all the fast modes of motion, the time step for integration can remain fairly large, speeding up the calculation process. Of special interest in the model is the damping which consists of aerodynamic damping and material-based damping. The relation between these two forms of damping is investigated. Verification of the model is done through comparison with analytical and real-life measured data. The resulting model is simulated in MSC ADAMS. It is shown that the aerodynamic damping is of prime interest because it dampens the slower motions. Material damping dampens mostly the fast vibrations.","kites; cable; simulation; dynamic modelling; model development; applications of simulation in engineering","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:c62ed836-019f-44c3-aa1b-a49ea1d61ba9","http://resolver.tudelft.nl/uuid:c62ed836-019f-44c3-aa1b-a49ea1d61ba9","Energy-based aeroelastic analysis of a morphing wing","De Breuker, R.; Abdalla, M.; Gürdal, Z.; Lindner, D.","","2007","Aircraft are often confronted with distinct circumstances during different parts of their mission. Ideally the aircraft should fly optimally in terms of aerodynamic performance and other criteria in each one of these mission requirements. This requires in principle as many different aircraft configurations as there are flight conditions, so therefore a morphing aircraft would be the ideal solution. A morphing aircraft is a flying vehicle that i) changes its state substantially, ii) provides superior system capability and iii) uses a design that integrates innovative technologies. It is important for such aircraft that the gains due to the adaptability to the flight condition are not nullified by the energy consumption to carry out the morphing manoeuvre. Therefore an aeroelastic numerical tool that takes into account the morphing energy is needed to analyse the net gain of the morphing. The code couples three-dimensional beam finite elements model in a co-rotational framework to a lifting-line aerodynamic code. The morphing energy is calculated by summing actuation moments, applied at the beam nodes, multiplied by the required angular rotations of the beam elements. The code is validated with NASTRAN Aeroelasticity Module and found to be in agreement. Finally the applicability of the code is tested for a sweep morphing manoeuvre and it has been demonstrated that sweep morphing can improve the aerodynamic performance of an aircraft and that the inclusion of aeroelastic effects is important.","morphing wing; aeroelastic analysis; generic analysis tool; actuator energy","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerospace Structures","","","",""
"uuid:56dd842b-1e8b-4845-908b-ed1e6c5ae171","http://resolver.tudelft.nl/uuid:56dd842b-1e8b-4845-908b-ed1e6c5ae171","A Conceptual Design and Optimization Method for Blended-Wing-Body Aircraft","Vos, R.; Van Dommelen, J.","","2012","This paper details a new software tool to aid in the conceptual design of blended-wingbody aircraft. The tool consists of four main modules. In the preliminary sizing model a class I estimate of the maximum take-off weight, wing loading, and thrust-to-weight ratio is calculated. This information is used together with an initial guess of the 30 design variables that to form a geometric model of the aircraft. From this geometric model four disciplinary models are derived: an aerodynamic model, a model of the wing box structure, a model for the cabin, and a model for the fuel tank. In the subsequent analysis module refined weight estimation for the operating-empty weight is being calculated, as well as the center-of-gravity shift during loading, the static margin, the main stability and control derivatives, and the harmonic range. In the last module, these analysis results are compared to 27 nonlinear constraints stemming from the top-level requirements and the aviation regulations. A gradient-based optimization routine is employed to find a combination of the design variables that satisfies all constraints while optimizing for harmonic range at constant maximum take-off weight. Between 20 and 60 iterations are required to achieve convergence. The tool has been set up to allow for maximum configurational flexibility such as forward-swept outer wings, under-the-wing engines, and twin vertical tails.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:c42fc09d-58b7-4126-a2d9-bd292c69cd71","http://resolver.tudelft.nl/uuid:c42fc09d-58b7-4126-a2d9-bd292c69cd71","Laddermill sail: A new concept in sailing","Podgaets, A.R.; Ockels, W.J.","","2007","A new innovative approach to sailing has been proposed by TU Delft. It allows sailing in any desired direction, including straight into the wind. The concept consists of generating energy with a sky sail and then using it in an electric motor of the ship. The paper describes a mathematical model of laddermill sail.","Laddermill; sailing; wind energy","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:e351753a-9535-444c-a28d-f20044ffdefc","http://resolver.tudelft.nl/uuid:e351753a-9535-444c-a28d-f20044ffdefc","SkelTre – fast skeletonisation for imperfect point cloud data of botanic trees","Bucksch, A.; Lindenbergh, R.; Menenti, M.","","2009","","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:62db827c-abd9-428a-8fd6-293a6da43c4d","http://resolver.tudelft.nl/uuid:62db827c-abd9-428a-8fd6-293a6da43c4d","Eolian sand transport monitored by terrestrial laser scanning","Lindenbergh, R.C.; Soudarissanane, S.S.; De Vries, S.; Coquet, M.; De Schipper, M.; Hejbudzka, K.; Duijnmayer, K.; Van Goor, B.; Cohen, A.","","2010","Morphodynamic changes at sandy coasts, as are dominant in The Netherlands, are typically monitored at yearly intervals by means of LIDAR. Meanwhile it is recognized that beach morphodynamics is not a regular process but is strongly correlated to meteorological conditions. A time series of 14 terrestrial laser scans of a beach experiment is analyzed, obtained during a time period of 88 hours characterized by changing weather conditions including strong wind and rain. It is shown that after a conversion to a suited spherical grid, different deformation regimes can be identified and that elevation changes rates below a millimeter an hour can be detected.","terrestrial laser scanning; change detection; eolian transport; coastal monitoring","en","conference paper","International Society of Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:589e7606-d9fb-453f-bf3f-2edae67dd5c1","http://resolver.tudelft.nl/uuid:589e7606-d9fb-453f-bf3f-2edae67dd5c1","Snapshot Software Receiver for GNSS in Weak Signal Environments: An Innovative Approach for Galileo E5","Carrasco-Martos, S.; López-Risueño, G.; Jiménez-Baños, D.; Gill, E.K.A.","","2010","Global Navigation Satellite System (GNSS) positioning has turned out to be an enabler of Location-Based Services (LBS). This has motivated in recent years an increasing research activity on signal processing techniques for GNSS receivers. However, one main limitation faced by these GNSS receivers is the propagation of GNSS signals in complex scenarios such as urban canyons and indoor, where signals suffer from high attenuation, severe multipath, near-far problem and non-Line Of Sight (LOS) propagation. These limitations have given rise to highly specialized GNSS receiver architectures, such as snapshot or one shot, overcoming the computational cost of the required processing algorithms and allowing manufacturers the integration of GNSS receivers in mobile platforms. They are commonly known as High Sensitivity GNSS (HSGNSS) receivers [8]. The European Galileo system will provide additional signals for usage and will most likely improve overall GNSS-based positioning, as well as the role of GNSS technology as an LBS enabler. Research on highsensitivity Galileo receivers has been quite limited so far; therefore an extensive research activity is necessary. Some effort on E1bc signals has been done, but E5 has not been sufficiently explored [1]. A higher bandwidth and the possibility of using two signals are an advantage in terms of performance in urban canyons or indoor. Nevertheless, a higher bandwidth translates in a higher sampling rate and computational load. The objective of this work focuses on the design, implementation and performance evaluation of a snapshot software receiver system that exploits the properties of Galileo E5 pilot signals to detect very weak signals, offering a simple yet efficient acquisition-based receiver. The design is based on an acquisition stage that uses efficient signal processing techniques to deliver delay- Doppler estimates and can lead to a position fix without requiring a tracking stage.","GPS; satellite navigation","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:371609fc-3435-4fb2-a884-1049cc768653","http://resolver.tudelft.nl/uuid:371609fc-3435-4fb2-a884-1049cc768653","Domain specific modeling languages to support model-driven engineering of aircraft systems","Van der Elst, S.W.G.; Van Tooren, M.J.L.","","2008","","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:83e43dd6-9890-47ca-bdb1-986b57ca6874","http://resolver.tudelft.nl/uuid:83e43dd6-9890-47ca-bdb1-986b57ca6874","Nonlinear Aeroelastic Study of Stall Induced Oscillation in a Symmetric Airfoil","Sarkar, S.; Bijl, H.","","2006","In this paper the aeroelastic stability of a wind turbine rotor in the dynamic stall regime is investigated. Increased flexibility of modern turbine blades makes them more susceptible to aeroelastic instabilities. Complex oscillation modes like flap/lead-lag are of particular concern, which give way to potential structural damage, see Chaviaropoulos (1999), Chaviaropoulos et.al. (2003). We study the stall induced oscillations in pitching direction and in combined flapwise, lead-lag wise directions. The aerodynamic loads acting on the rotor body in the stall regime are nonlinear. We consider a wide ranging parametric variation and underline their effect on the aeroelastic instability and overall nonlinear dynamical behavior of the system. A common engineering dynamic stall model (Onera) has been used to calculate the aerodynamic loads, (see Tran and Petot (1981), Dunn and Dugundji (1992). The aerodynamic loads are captured well by this model in the dynamic stall regime and are subsequently used to predict the bifurcation behavior and the chaotic routes of the aeroelastic system under study are . The aerodynamic loads are given in terms of differential equations which are combined with the governing equations of the aeroelastic system; the resulting system of equations are solved by a 4th order variable step Runge-Kutta method. In the pitching oscillation study we consider the following parameters: nondimensional airspeed (U), mean angle of attack, initial condition, structural nonlinearity and reduced frequency (k) and amplitude of external forcing. The self excited and forced system reveal existence of quasi-periodic and chaotic response. For different mean angle of attack, quasi-periodic response have been obtained with different initial conditions. A cubic structural nonlinearity has been seen to alter the bifurcation pattern of the above system. Varying k as a bifurcation parameter in the forced system shows presence of period-3 orbits near chaos. The second case of flap/edgewise oscillation in the stall regime identifies nondimensional rotational speed of the rotor along with structural stiffnesses and nonlinearity as most important parameters of the self excited system. However, no chaotic response has been obtained. External forcing shows presence of higher harmonics and quasi-harmonics in the response. Once again, no chaotic attractor has been found.","dynamic stall; aeroelastic stability; nonlinear behavior","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2e8dac7e-57a4-461d-ae0d-c4047330076a","http://resolver.tudelft.nl/uuid:2e8dac7e-57a4-461d-ae0d-c4047330076a","On the universality of PIV uncertainty quantification by image matching","Sciacchitano, A.; Scarano, F.; Wieneke, B.","","2013","The topic of uncertainty quantification in particle image velocimetry (PIV) is recognized as very relevant in the experimental fluid mechanics community, especially when dealing with turbulent flows, where PIV plays a prime role as diagnostic tool. The issue is particularly important when PIV is used to assess the validity of results obtained with computational fluid dynamics (CFD). An approach for PIV data uncertainty quantification based on image matching has been introduced by Sciacchitano et al [1], where the contribution of individual particle images to the correlation peak is analyzed and the uncertainty is retrieved from the ensemble of particle image disparities. In this paper, the universality of the approach’s working principle is investigated via the application to a wide gamut of experimental data of flows ranging from laminar to turbulent regime and from subsonic to supersonic. Also a methodology for evaluating the performance of the image-matching approach in different experimental conditions is proposed.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:2ea1b27b-b92c-4ce9-b097-b17303a1bcf6","http://resolver.tudelft.nl/uuid:2ea1b27b-b92c-4ce9-b097-b17303a1bcf6","Design of a 100 MW laddermill for wind energy generation from 5 km altitude","Lansdorp, B.; Ockels, W.","","2005","This paper presents the design of a 100 MW Laddermill. The Laddermill is a novel concept to generate electricity from high altitude winds. The concept allows very large single unit powers. It generates electricity by pulling a rope from a generator, with lift generated by kites. For a 100 MW Laddermill 50 kites are distributed evenly in the top 5 km of a 6.5 km long rope. 500 m of the rope is wound around the generator. The kites pull the 500 m of rope from the generator, thus driving it. Subsequently the kites fly down in a configuration that generates significantly less lift than during the ascent. This way the tether is retrieved and the process is repeated. The 50 kites required for a 100 MW Laddermill each have the wing surface of two soccer fields, or 13.000 m2. Large controllable kites are thus an enabling technology for the Laddermill. Preliminary results including a practical demonstration exist. The tether will be tapered, with a diameter of 24 cm at ground level to 4 cm at the altitude of the highest kite. The groundstation will feature a large drum for the cable, a gearbox and some cable guidance equipment. The whole groundstation can be rotated to align with the wind direction. The groundstation is connected to 2000 tons of ballast which prevents the kites from lifting the groundstation from the ground. This paper discusses several design options considered for the Laddermill concept and the groundstation. It also reports on the results of tests that are performed in which the Laddermill principle is demonstrated and the first Laddermill electricity is produced.","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:29ee20c5-32ad-447d-9c3b-3798511e9e49","http://resolver.tudelft.nl/uuid:29ee20c5-32ad-447d-9c3b-3798511e9e49","Unsteady adaptive stochastic finite elements for quantification of uncertainty in time-dependent simulations","Witteveen, J.A.S.; Bijl, H.","","2008","","","en","conference paper","Civil-Comp Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:927d1389-4faa-46ed-9e1f-5ecf6967f2ce","http://resolver.tudelft.nl/uuid:927d1389-4faa-46ed-9e1f-5ecf6967f2ce","Developing a strategic framework for an airline dealing with the EU emission trading scheme","Van Hasselt, M.; Van der Zwan, F.; Ghijs, S.; Santema, S.","","2009","The European Commission has decided that the aviation sector will be included in the EU Emission Trading Scheme (ETS) in 2012. This has significant impacts on the business and the strategy of airlines. All of a sudden, airlines must possess emission rights in order to be able to operate their aircraft. Given the uncertainty over how exactly the EU ETS is going to be implemented in the next few years and the unexpected fluctuations in prices of fuel and the CO2 emission rights, airlines are faced with a multifaceted challenge: how to best incorporate EU ETS in the business strategy of an airline? In order to support airlines with this complex process, in this research project a strategy model with different regulatory scenarios is developed, with which the exposure of an airline to EU ETS can be calculated. The model has been piloted in an airline to determine how future airline strategy should be adopted based on the regulatory environment. It is clear from the analysis of the different scenarios, that every regulatory scenario has its own optimal strategy, ranging from increasing fuel efficiency to using alternative types of fuel.","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:38b3bc27-55d0-45ea-a035-8dc0a6dc88e9","http://resolver.tudelft.nl/uuid:38b3bc27-55d0-45ea-a035-8dc0a6dc88e9","Efficiency of kite power systems in pumping operation","Fechner, U.; van der Vlugt, R.; Schmehl, R.; Ockels, W.J.","","2011","Seminar organized by Delft University Wind energy research institute for European Academy of Wind Energy","Airborne Wind Energy; AWE; kite power; pumping operation; jojo operation; winch; efficiency","en","conference paper","The European Academy of Wind Energy, EAWE","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f7de4dcb-63a6-455a-bb30-97d383c4a216","http://resolver.tudelft.nl/uuid:f7de4dcb-63a6-455a-bb30-97d383c4a216","Simplified fatigue assessment of offshore wind support structures accounting for variations in a farm (poster)","Michalopoulos, M.; Zaayer, M.B.","","2015","Provided the significant contribution of support structures to the capital expenditures of offshore wind, optimisation schemes are often developed to address the need for tailored design of different structures in one farm. A crucial aspect of them is, among others, the Fatigue Limit State (FLS)1234 .To this direction, research is conducted on the response of the structure to cyclic loading in the frequency-domain567 . However, the complexity and the need for advanced software (finite element and/or aero-elastic codes) often limit the flexibility. As a consequence, the design process is not facilitated significantly. The focus of this study is principally placed on the impact that variations in an offshore wind farm (OWF) have on the support structures, particularly on their resistance to cumulative damage caused by wind and wave loading. The vital requirement is therefore that the procedure is computationally affordable to ensure applicability for the early design phase of multiple structures. The goal of this study is to develop such a procedure.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:aebb0075-4499-48c2-8a81-286a35667eb2","http://resolver.tudelft.nl/uuid:aebb0075-4499-48c2-8a81-286a35667eb2","Configuration management in nanosatellites projects: Evalaution of Delfi-C3 and consequent adaption for Delfi-n3Xt","Genbrugge, M.E.A.; Teuling, R.; Kuiper, J.M.; Brouwer, G.F.; Bouwmeester, J.","","2009","The Delfi-C3 nano-satellite was launched in April 2008 and the development of its successor, the Delfi-n3Xt, is ongoing. Both of these projects are conducted by students from the Delft University of Technology as a corporation between the Aerospace Engineering Faculty, the Faculty of Electrical Engineering, Mathematics and Computer Science and several industrial partners. This paper provides a description and evaluation of the configuration management that was applied at the Delfi-C3 nano-satellite project. It was done by comparing the initial intentions with the final implementation. More specifically, the interface control, configuration control, requirements management and the documentation management are discussed. An evaluation of the configuration management of the Delfi-C3 project was appropriate, as based on the lessons that were learned an improved configuration management approach for the Delfi-n3Xt project had to be defined. The need for simplification and increased consistency on all the aspects of the configuration management were the main conclusions of this evaluation. Basically, deciding on a configuration-strategy and controlling its consistency as early as possible creates a framework on which the rest of the systems engineering tasks can be build. To provide some insight in the practical implementation of the approach, it will be presented how it was used for the initial design of the Electrical Power System (EPS). Finally, the benefits and remaining issues will be discussed.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:b94c19f1-0066-4419-b798-80a816f2ccd4","http://resolver.tudelft.nl/uuid:b94c19f1-0066-4419-b798-80a816f2ccd4","Lagrangian and Eulerian views into a turbulent boundary layer flow using time-resolved tomographic PIV","Schroder, A.; Geisler, R.; Staack, K.; Wieneke, B.; Elsinga, G.E.; Scarano, F.; Henning, A.","","2008","","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:779863bc-aec3-4750-920b-cb249a752bac","http://resolver.tudelft.nl/uuid:779863bc-aec3-4750-920b-cb249a752bac","Design tradeoffs for fiber composite fuselages under dynamic loads using structural optimization","Baluch, H.A.; Van Tooren, M.J.L.; Schut, E.J.","","2008","","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:921eba0a-7a07-42d6-a3c5-66548db09009","http://resolver.tudelft.nl/uuid:921eba0a-7a07-42d6-a3c5-66548db09009","A Non-Linear Upscaling Approach for Wind Turbines Blades Based on Stresses","Castillo Capponi, P.; Van Bussel, G.J.W.; Ashuri, T.; Kallesoe, B.","","2011","The linear scaling laws for upscaling wind turbine blades show a linear increase of stresses due to the weight. However, the stresses should remain the same for a suitable design. Application of linear scaling laws may lead to an upscaled blade that may not be any more a feasible design. In this paper a non-linear upscaling approach is presented with the aim of keeping the stresses in the upscaled blade the same as the reference blade. The stresses due to the weight, aerodynamics and centrifugal forces are taken into account and the blade is modeled as a beam with equivalent structural properties. This new methodology is used to upscale the 5 MW NREL wind turbine blade to a 20 MW wind turbine blade. As a result, a 20 MW wind turbine blade is obtained in which the stresses are the same as the 5 MW blade. This provides initial blade design solution for optimization studies that is feasible and enables the designer to explore other interesting aspects of larger scale wind turbines.","wind turbines blade design; non-linear scaling law; Blades aeroelasticity; upscaling","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:8d23dd5e-92bc-478b-a3c4-72b743ff84df","http://resolver.tudelft.nl/uuid:8d23dd5e-92bc-478b-a3c4-72b743ff84df","When to STAMP? A case study in aircraft ground handling services","Passenier, D.; Sharpanskykh, A.; De Boer, R.J.","","2015","In this paper we show that safety analysis using the STAMP causation model is limited in the extent to which it appreciates complex dynamics of safety. When the STAMP is applied as management tool, controls may be introduced too soon in the analysis since it is necessary to understand emergent behaviour first. Emergent behaviour can be studied through organizational ethnography in parallel development with an agent-based model, as illustrated in a case study of airport ground handling services. Based on ethnographic research and theories from psychology and social sciences, we developed an agent model that showed why repeated attempts at managerial control to improve employees’ safety compliance were not durable. The insights obtained through the case study attained to move management ideas about what control means towards creating smarter design and communication processes that involve the work force.","STAMP; organizational ethnography; agent modelling; safety management; aviation","en","conference paper","Elsevier","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:ff0ad074-81b2-497e-9255-3e38deae3954","http://resolver.tudelft.nl/uuid:ff0ad074-81b2-497e-9255-3e38deae3954","A cohesive elements based model to describe fracture and cohesive healing in elastomers","Baldi, A.; Grande, A.M.; Bose, R.K.; Airoldi, A.; Garcia Espallargas, S.J.; Di Landro, L.; Van der Zwaag, S.","","2013","Several polymeric systems with intrinsic Self-Healing (SH) capabilities have been reported in literature. Many of them showed healing upon contact across the crack interface. Different parameters such as contact time, temperature, pressure or chemical activity determine the degree of healing obtained. In this work, a numerical simulation of the healing efficiency as a function of the environment is proposed based on the use of cohesive elements in a finite element model. Cohesive elements are commonly used to model interlaminar fracture mechanisms in composite materials. In this work, they are adopted to simulate both failure and subsequent healing by a specific SH elastomeric system. The SH elastomeric system is initially characterised by means of the identification of its conventional mechanical properties. From these results, a hyperelastic constitutive model is selected. At the same time, a model simulating fracture mechanics and healing mechanics is established and validated using a cohesive failure model in a commercial explicit finite element code. Finally, the two models are combined to evaluate the capability of the proposed numerical approach to simulate: (i) the restoration of contact of the two separated sides of the material during their rejoining, and (ii) the restoration of the mechanical properties of the elastomeric system. This later stage is directly linked to the healing efficiency. While the model does not yet capture all features of healing, it offers attractive features worth further exploring also for other SH systems.","explicit finite element analyses; cohesive elements; elastomer","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:e7148dbf-c609-415d-90a6-7e481d9795f8","http://resolver.tudelft.nl/uuid:e7148dbf-c609-415d-90a6-7e481d9795f8","Controller Design Automation for Aeroservoelastic Design Optimization of Wind Turbines","Ashuri, T.; Van Bussel, G.J.W.; Zaayer, M.B.; Van Kuik, G.A.M.","","2010","The purpose of this paper is to integrate the controller design of wind turbines with structure and aerodynamic analysis and use the final product in the design optimization process (DOP) of wind turbines. To do that, the controller design is automated and integrated with an aeroelastic simulation tool. This integrated tool is linked with an optimization engine. The automated controller has two built-in control algorithms; a generator-torque controller and an above rated pitch-controller. This new tool is used in the DOP of the 5MW NREL research wind turbine. To show how this method works some parameters of both the generatortorque controller and the pitch-controller are introduced as design variables in the DOP. As the result of changing controller related design variables within each optimization iteration, the values of the objective function and the design constraint also change. This shows that by introducing the controller’s parameters as design variables in the DOP a more realistic assessment of the objective function and constraints is possible that helps the optimizer to search for better solutions.","controller design; wind turbine; design optimization; aeroservoelasticity","en","conference paper","European Wind Energy Association","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:4db6d63a-2058-4e6e-9f70-d210b36211dc","http://resolver.tudelft.nl/uuid:4db6d63a-2058-4e6e-9f70-d210b36211dc","Topology optimization of pressure adaptive honeycomb for a morphing flap","Vos, R.; Scheepstra, J.; Barrett, R.","","2011","The paper begins with a brief historical overview of pressure adaptive materials and structures. By examining avian anatomy, it is seen that pressure-adaptive structures have been used successfully in the Natural world to hold structural positions for extended periods of time and yet allow for dynamic shape changes from one flight state to the next. More modern pneumatic actuators, including FAA certified autopilot servoactuators are frequently used by aircraft around the world. Pneumatic artificial muscles (PAM) show good promise as aircraft actuators, but follow the traditional model of load concentration and distribution commonly found in aircraft. A new system is proposed which leaves distributed loads distributed and manipulates structures through a distributed actuator. By using Pressure Adaptive Honeycomb (PAH), it is shown that large structural deformations in excess of 50% strains can be achieved while maintaining full structural integrity and enabling secondary flight control mechanisms like flaps. The successful implementation of pressure-adaptive honeycomb in the trailing edge of a wing section sparked the motivation for subsequent research into the optimal topology of the pressure adaptive honeycomb within the trailing edge of a morphing flap. As an input for the optimization two known shapes are required: a desired shape in cruise configuration and a desired shape in landing configuration. In addition, the boundary conditions and load cases (including aerodynamic loads and internal pressure loads) should be specified for each condition. Finally, a set of six design variables is specified relating to the honeycomb and upper skin topology of the morphing flap. A finite-element model of the pressure-adaptive honeycomb structure is developed specifically tailored to generate fast but reliable results for a given combination of external loading, input variables, and boundary conditions. Based on two bench tests it is shown that this model correlates well to experimental results. The optimization process finds the skin and honeycomb topology that minimizes the error between the acquired shape and the desired shape in each configuration","pressure adaptive, honeycomb, cellular structure, pneumatic, morphing","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerospace Structures and Design Methodology","","","",""
"uuid:22064eb0-ac70-4d7a-ad2b-35f98a7df0a7","http://resolver.tudelft.nl/uuid:22064eb0-ac70-4d7a-ad2b-35f98a7df0a7","Attitude and orbital dynamics modeling for an uncontrolled solar-sail experiment in low-Earth orbit","Pirovano, L.; Seefeldt, P.; Dachwald, B.; Noomen, R.","","2015","Gossamer-1 is the first project of the three-step Gossamer roadmap, the purpose of which is to develop, prove and demonstrate that solar-sail technology is a safe and reliable propulsion technique for long-lasting and high-energy missions. This paper firstly presents the structural analysis performed on the sail to understand its elastic behavior. The results are then used in attitude and orbital simulations. The model considers the main forces and torques that a satellite experiences in low-Earth orbit coupled with the sail deformation. Doing the simulations for varying initial conditions in attitude and rotation rate, the results show initial states to avoid and maximum rotation rates reached for correct and faulty deployment of the sail. Lastly comparisons with the classic flat sail model are carried out to test the hypothesis that the elastic behavior does play a role in the attitude and orbital behavior of the sail.","solar sail; Gossamer structures; attitude dynamics; orbital dynamics","en","conference paper","DLR","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:ad447a7f-1281-4790-8e6b-85d1fa5aa526","http://resolver.tudelft.nl/uuid:ad447a7f-1281-4790-8e6b-85d1fa5aa526","Noise reduction by range image filtering","Lesparre, J.","","2009","Three-dimensional models are usually a severe simplification of the real world. Laser scans that are used to make these models have a high resolution and potentially contain much more spatial information. This potential can often not be exploited due to the measurement noise present in the data. The question addressed in this paper is how to remove the measurement noise without simplifying the model more than necessary. The proposed method solves this problem by using the redundancy present due to the high spatialresolution. By smoothing the data according to the probability and observation theory, a best linear unbiased prediction of the surface is obtained. This is implemented for range image filtering, and tested on synthetic data. The results show that this is a powerful method for the smoothing of noisy 3D data.","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:35d6e52b-9620-47d2-917a-952487951787","http://resolver.tudelft.nl/uuid:35d6e52b-9620-47d2-917a-952487951787","UAV visual signature suppression via adaptive materials","Barrett, R.; Melkert, J.","","2005","Visual signature suppression (VSS) methods for several classes of aircraft from WWII on are examined and historically summarized. This study shows that for some classes of uninhabited aerial vehicles (UAVs), primary mission threats do not stem from infrared or radar signatures, but from the amount that an aircraft visually stands out against the sky. The paper shows that such visual mismatch can often jeopardize mission success and/or induce the destruction of the entire aircraft. A psycho-physioptical study was conducted to establish the definition and benchmarks of a Visual Cross Section (VCS) for airborne objects. This study was centered on combining the effects of size, shape, color and luminosity or effective illumance (EI) of a given aircraft to arrive at a VCS. A series of tests were conducted with a 6.6ft (2m) UAV which was fitted with optically adaptive electroluminescent sheets at altitudes of up to 1000 ft (300m). It was shown that with proper tailoring of the color and luminosity, the VCS of the aircraft dropped from more than 4,200cm2 to less than 1.8cm2 at 100m (the observed lower limit of the 20-20 human eye in this study). In laypersons terms this indicated that the UAV essentially “disappeared.” This study concludes with an assessment of the weight and volume impact of such a Visual Suppression System (VSS) on the UAV, showing that VCS levels on this class UAV can be suppressed to below 1.8cm2 for aircraft gross weight penalties of only 9.8%.","visual signature suppression; electroluminescence; visual stealth; low obervables","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerospace Science for Sustainable Engineering and Technology","","","",""
"uuid:de608e7a-a36e-48a3-bc94-0cc25c16dd10","http://resolver.tudelft.nl/uuid:de608e7a-a36e-48a3-bc94-0cc25c16dd10","This hypothesis suggests new ways for looking at extraterrestrial life.","Ockels, W.J.","","2007","From his personal experience during a space flight (Challenger 1985) onward, the author has been struck repeatedly by the remarkable influence of Earth's environment on life, in particular by its most inevitable elements: time and gravity. Our life might be peculiar to the local Earth conditions, and not cosmic per se.","","en","conference paper","IAF/IAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4cff40af-0398-46dd-ab9d-43bd30d8e42a","http://resolver.tudelft.nl/uuid:4cff40af-0398-46dd-ab9d-43bd30d8e42a","On the possibility of using site data for offshore wind turbine design","Sathe, A.R.","","2007","","","en","conference paper","European Wind Energy Agency EWEA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:45418aca-f3ad-4395-934e-4f7b11f781db","http://resolver.tudelft.nl/uuid:45418aca-f3ad-4395-934e-4f7b11f781db","Incremental approximate dynamic programming for nonlinear flight control design","Zhou, Y.; Van Kampen, E.J.; Chu, Q.P.","","2015","A self-learning adaptive flight control design for non-linear systems allows reliable and effective operation of flight vehicles in a dynamic environment. Approximate dynamic programming (ADP) provides a model-free and computationally effective process for designing adaptive linear optimal controllers. This paper presents an incremental ADP (iADP) method which combines ADP method and incremental control techniques to design an adaptive near-optimal nonlinear controller. This nonlinear control method does not need any information of the dynamic model, but requires only the considered state (full state) and measured input and output. The iADP method was implemented on an F-16 aircraft simulation model. The results prove the success of the proposed method and show a potential approach of iADP nonlinear flight controllers without knowing full state.","","en","conference paper","","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:202a5e4e-aabb-4e60-b22f-4b46aea2a41b","http://resolver.tudelft.nl/uuid:202a5e4e-aabb-4e60-b22f-4b46aea2a41b","Influence of surface preparation on fusion bonding of thermoplastic composites","Sacchetti, F.; Grouve, W.J.B.; Warnet, L.L.; Fernandez Villegas, I.","","2015","Carbon fibre-reinforced thermoplastic composites laminates (CFRP) meant for fusion bonding have been moulded using different release media. The potential contamination of the laminate surface by the release media and its effect on the mechanical performance of fusion bonded joints was studied. The physical and chemical state of the bonding surface were analysed with surface energy and roughness measurements. The chemical composition of the laminate surfaces has been investigated by X-ray photoelectron spectroscopy (XPS). The laminates were then fusion bonded through co-consolidation. The mechanical performance of the bonds was studied by a mode I fracture toughness measurement using the double cantilever beam (DCB) test. The results show significant effect of contaminations on mechanical performance of the joints.","fusion bonding,; co-consolidation; (mould) surface preparation; fracture mechanics; X-ray photoelectron spectroscopy","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:383c1163-245d-47a7-bd0c-1f2229fb1849","http://resolver.tudelft.nl/uuid:383c1163-245d-47a7-bd0c-1f2229fb1849","Flow visualization of swept wing boundary layer transition","Serpieri, J.; Kotsonis, M.","","2015","In this work the flow visualization of the transition pattern occurring on a swept wing in a subsonic flow is presented. This is done by means of fluorescent oil flow technique and boundary layer hot-wire scans. The experiment was performed at Reynolds number of 2:15 . 106 and at angle of attack of -3º. At these conditions, three different flows are investigated: a natural transition case and two other ones where instead the transition mechanism, the stationary cross-flow waves, was forced with discrete roughness elements. Previously published results on similar flows were confirmed for two of the three tested configurations (natural transition and boundary layer forcing at the wavelength of the dominant stationary mode) while, for the third one (where a sub-critical wavelength was forced), some discrepancies are observed. A parametric study on the effect of the Reynolds number and the angle of attack is also presented.","3D subsonic boundary layer transition; cross-flow stationary waves; oil flow visualization; hot-wire","en","conference paper","Universita di Napoli Federico II","","","","","","","","Aerospace Engineering","Aerospace Structures & Computational Mechanics","","","",""
"uuid:5fd235c3-7d15-4519-9358-fbd4b67659ea","http://resolver.tudelft.nl/uuid:5fd235c3-7d15-4519-9358-fbd4b67659ea","Fundamentals of tomographic parricle image velocimetry","Scarano, F.","","2008","","","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4ff8662b-0b43-472a-b881-f718e0d5b21f","http://resolver.tudelft.nl/uuid:4ff8662b-0b43-472a-b881-f718e0d5b21f","Characterization of flow unsteadiness in a shock wave turbulent boundary layer interaction by means of dual-PIV","Souverein, L.J.; Van Oudheusden, B.W.; Scarano, F.","","2008","","","en","conference paper","TUD/EWA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f7b12bba-73f6-4141-bd34-d7861bdb0692","http://resolver.tudelft.nl/uuid:f7b12bba-73f6-4141-bd34-d7861bdb0692","Designing their own Future: Teaching Students how to Design Aerospace Operations Research","Saunders, G.N.; Curran, R.","","2011","This paper tells of the development of a course designed to help students set up their own operations research projects. The course was taught in a lecture format with much room for interaction and the students were required to make submit formal research plans for their operations research projects as well as literature review. The initial results from course evaluations show a significant improvement in student’s self-perceived level of preparedness for their Master thesis as well as a high satisfaction with the course itself.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:1019a338-5f69-409a-a06c-6c8346cd343e","http://resolver.tudelft.nl/uuid:1019a338-5f69-409a-a06c-6c8346cd343e","Metropolis: Relating airspace structure and capacity for extreme traffic densities","Sunil, E.; Hoekstra, J.M.; Ellerbroek, J.; Bussink, F.; Nieuwenhuisen, D.; Vidosavljevic, A.; Kern, S.","","2015","Personal and unmanned aerial vehicles have received increasing media attention over the last decade. As a result of the growing excitement for these two aircraft types, many within and outside the aerospace industry envision a future in which large numbers of small aircraft fly over urban areas. With this vision for the future, the question arises what would be required, in terms of airspace organization, to make this feasible, or indeed, if it will be possible at all. In this context, the Metropolis project aims to investigate the influence of airspace structure on capacity, complexity, safety, and efficiency for high-density airspace. To this end, four airspace concepts, ranging from a decentralized direct routing concept, to a highly structured tube network using 4D trajectory-based operations, have been considered. The four concepts were compared by means of large-scale simulation experiments, for multiple scenarios that are extreme when compared to current air traffic densities. This paper presents an overview of the Metropolis project with a focus on the project objectives, design and implementation of airspace concepts, and preliminary simulation results.","airspace structure; urban airspace design; air traffic control; free flight; 4D trajectory based operations; Personal Aerial Vehicles (PAVs); Unmanned Aerial Vehicles (UAVs)","en","conference paper","FAA / Eurocontrol","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:e9724441-a973-4b32-b568-3a610aff9c9f","http://resolver.tudelft.nl/uuid:e9724441-a973-4b32-b568-3a610aff9c9f","Design of Fiber-steered Variable-stiffness Laminates Based on a Given Lamination Parameters Distribution","Van Campen, J.M.J.F.; Kassapoglou, C.; Gürdal, Z.","","2011","Mechanical properties of fiber-reinforced laminated composite materials are directionally dependent. Contemporary laminated composite design aims to make effective use of these directional properties by means of stacking sequence design, selecting the fiber orientation angle of each ply from a predefined set. Automated fiber-placement (AFP) technology can be used to improve the efficacy of composite materials by means of fiber steering. The variation of fiber orientation angles per ply of the laminate yields a variable stiffness (VS) laminate. For optimization purposes it is attractive to design such laminates in terms of lamination parameters (LP), as the number of design variables per point in the structure can be reduced to as little as four dimensionless variables considering balanced symmetric layups, and because many lay-up optimization problems can be made convex by describing them in terms of LPs. VS laminate design in terms of LP requires the obtained LP distribution to be converted into an actual fiber angle design. In a previous study the authors proposed a method to convert VS laminate designs using LPs into fiber angle designs. This method includes a constraint on in-plane curvature, a manufacturing constraint related to AFP. Thickness build-up will occur due to fiber steering. The amount of thickness build-up that results from the obtained fiber angle designs is discussed here as a function of the constraint on fiber curvature. The streamline analogy is used to obtain an estimate for thickness build-up and to determine fiber paths. A square plate loaded in biaxial compression is used to demonstrate the effect of the in-plane curvature constraint on thickness build-up, and several fiber angle designs, thickness distributions and fiber paths are given for this structure.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:23f260da-c0cc-4e23-97c8-57c21b9efa50","http://resolver.tudelft.nl/uuid:23f260da-c0cc-4e23-97c8-57c21b9efa50","Energy based study of quasi-static delamination as a low cycle fatigue process","Amaral, L.; Yao, L.; Alderliesten, R.C.; Benedictus, R.","","2015","This work proposes to treat quasi-static mode I delamination growth of CFRP as a low-cycle fatigue process. To this end, mode I quasi-static and fatigue delamination tests were performed. An average physical Strain Energy Release Rate (SERR), derived from an energy balance, is used to characterize the energy released in crack extension. The physical SERR is then compared to the SERRs calculated by the ASTM standard, and the physical background of the standard is questioned. Furthermore, when normalizing the physical SERR for fatigue delamination by the one obtained for quasi-static crack extension, a stress ratio dependence is observed. This stress ratio effect is physically explained to be present due to the relation between quasi-static and fatigue loading at high stress ratios.","","en","conference paper","VTT Technical Research Centre of Finland","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:34bb3fa4-a9cc-4c68-bab9-a7ad537dcd88","http://resolver.tudelft.nl/uuid:34bb3fa4-a9cc-4c68-bab9-a7ad537dcd88","Value Analysis of Engine Maintenance Scheduling relative to Fuel Burn and Minimal Operating Costs","Curran, R.; Van der Zwan, F.M.; Ouwehand, A.; Ghijs, S.S.A.","","2010","The paper presents the results from a study in collaboration with an airline that looked at modeling the relationship of maintenance and fuel burn costs relative to minimizing the life cycle cost relative to schedule. The work has verified that the bucket theory presented in the paper is a correct and has a direct impact on the scheduling interval. Ultimately, it was found that the maintenance schedule at the collaborating company was overly long and could be reduced by 15-20%, to reduce total costs in the longer term. The Genetic-Causal Approach was used in the cost modelling process and incorporated into the Value Operations Methodology. Consequently, the generic relevance of both these theories has been validated through the work presented.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:48acad55-f0d8-4f02-b8b5-fda935fa60a1","http://resolver.tudelft.nl/uuid:48acad55-f0d8-4f02-b8b5-fda935fa60a1","Multi-Level Acceleration for Sub-Iterations in Partitioned Fluid-Structure Interaction","Van Zuijlen, A.H.; Bijl, H.","","2009","Computational fluid-structure interaction is most commonly performed using a partitioned approach. For strongly coupled problems sub-iterations are required, increasing computational time as flow and structure have to be resolved multiple times every time step. Many sub-iteration techniques exist that improve robustness and convergence, although still a flow and structure have to be solved a number of times every time step.In this paper we apply a multi-level acceleration technique, which is based on the presumed existing multi-grid solver for the flow domain, to a two-dimensional strongly coupled laminar and turbulent problem and investigate the combination of multi-level acceleration with the Aitken underrelaxation technique. It is found that the value for the underrelaxation parameter is not significantly different when performing sub-iterations purely on the coarse level or purely on the fine level. Therefore coarse and fine level sub-iterations are used alternatingly, where it is found that performing 3 or 4 coarse level sub-iterations followed by 1 fine level sub-iteration resulted in the highest gain in efficiency. Although the total number of sub-iterations increases slightly by 25–30%, the number of fine grid iterations can be decreased by as much as 65–70%.","computational fluid dynamics; optimisation; finite volume methods","en","conference paper","American Institute of Physics","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3ea4841c-14f8-4ce3-a235-29c573635c78","http://resolver.tudelft.nl/uuid:3ea4841c-14f8-4ce3-a235-29c573635c78","Determination of the extreme value in the response of wind turbines by means of constrained stochastic simulation","Bierbooms, W.A.A.M.","","2008","","","en","conference paper","American Institute of Aeronautics and Astronautics AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a4cc00f5-0acd-4c25-bda5-acf72db828b4","http://resolver.tudelft.nl/uuid:a4cc00f5-0acd-4c25-bda5-acf72db828b4","The YES2 Experience: Towards Sustainable Space Transportation using Tethers","Van der Heide, E.J.; Kruijff, M.; Ockels, W.J.","","2008","Today there is no common vision on sustainable space transportation. Rockets expel gasses and solid rockets often small particles. These have negative effect on the environment, but it is not understood to what extent. With ever growing demand for access to space, sustainable technology developments are to be made. In this respect a truly sustainable means of transportation seems to be the space elevator. However state of the art tether technology can already contribute today to sustainability and further tether developments are stepping stones for sustainable space transportation. This paper provides firstly an outlook into sustainable space transportation, from a mainly European perspective. Here we address that tethers are a building block for sustainable space transportation and hence technological advancements are of key interest. Potential next steps for Europe are discussed. We then zoom in further towards the state of the art for tethers in Europe, mainly based on the results of the 2nd Young Engineers' Satellite (YES2) project, that completed a 32 km tether deployment in September 2007, and of which the technology and design is publicly available. Discussed are the YES2 tether deployer system, its scalability and supporting rigs/tools as well as the hurdles encountered on the road from concept to space demonstration such as critics' concerns about safety and simulation validity. We address tether controllability, based on mission results, showing good agreement between tests, simulations and YES2's flight measurements of the various deployment parameters. Observations of tether stiffness, damping, sound waves and lateral waves are analyzed including conclusions on scope of validity of simulation and test. We conclude that Europe can take a prominent role in sustainable space transportation development.","","en","conference paper","International Academy of Astronautics","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:8cbad926-4ed4-46c4-9df8-a0ce66ad274c","http://resolver.tudelft.nl/uuid:8cbad926-4ed4-46c4-9df8-a0ce66ad274c","Modelling manual control of straight trajectories with a perspective flight-path display","Mulder, M.","","1996","","perspective flight-path display; manual controi; human operator modelling","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b9c58768-8bd2-45fe-8601-056059475f46","http://resolver.tudelft.nl/uuid:b9c58768-8bd2-45fe-8601-056059475f46","On the reliability of spacecraft swarms","Engelen, S.; Gill, E.K.A.; Verhoeven, C.J.M.","","2012","Satellite swarms, consisting of a large number of identical, miniaturized and simple satellites, are claimed to provide an implementation for specific space missions which require high reliability. However, a consistent model of how reliability and availability on mission level is linked to cost- and time-effective design of the individual swarm satellites has not yet been done. We have established a method to model how applied technology and processes for designing swarm satellites under cost and time constraints impact the system-level performance of swarms. The method is applied and discussed for a future astronomy mission using a satellite swarm. Swarm satellites are severely constrained by mass, as they have to be produced in large numbers. This generally implies that they feature drastically reduced internal redundancy. This is only acceptable when all satellites are functionally identical, and can hence take over certain tasks of a malfunctioning satellite, resulting in a graceful degradation of the system performance. This swarm feature renders it significantly flexible and robust, yet it potentially affects its reliability and system throughput. Therefore, in this paper we investigated and show how the reliability of an individual satellite transfers into the overall system reliability, and hence the associated throughput of the swarm as a whole. We generated a generic model of a simple swarm satellite, and used it in conjunction with a Markov-chain based reliability analysis to assess the impact of a failure of each of the sub-systems on the functionality of the individual satellite, as well as its impact on the functionality of the swarm. Further analysis was done using Monte-Carlo simulations. The research focussed mainly on the (useful) lifetime of the system as a whole both when considering full and partial failures of elements. This was done using the assumption that swarm elements could still function in a reduced operational state when non-critical components failed. Also, the effect of recoverable malfunctions is investigated.","","en","conference paper","ESA European Space Agency","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:b7098aac-56a4-4fb6-a983-a66732093d60","http://resolver.tudelft.nl/uuid:b7098aac-56a4-4fb6-a983-a66732093d60","Investigation of Practical Flight Envelope Protection Systems for Small Aircraft","Falkena, W.; Borst, C.; Mulder, J.A.","","2010","Personal air transportation utilizing small aircraft is a market that is expected to grow significantly in the future. For this segment, “stick and rudder” related accidents should be mitigated to guide this process in a safe manner. Instead of downscaling advanced and expensive fly-by-wire platforms that incorporate flight envelope protection found in commercial aircraft, a low cost solution should be considered. This paper focuses on a flight envelope protection system for small aircraft, to allow carefree maneuvering for the less experienced pilot. Preliminary results are obtained from an empirical comparison study in the time domain, between a PID based control limiting approach, a command limiting approach and a constrained Flight Control Law (FCL) approach using Model-based Predictive Control (MPC), with and without parametric model uncertainties. Investigation of the results reveals that, for this study, command limiting and MPC should be preferred over control limiting and that the practicality of command limiting outweighs the small performance increase of MPC.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:97d32339-1fff-48a2-a222-d5305fd66f61","http://resolver.tudelft.nl/uuid:97d32339-1fff-48a2-a222-d5305fd66f61","Development of a System Level Tool for Conceptual Design of Small Satellites","Aas, C.L.O.; Zandbergen, B.T.C.; Hamann, R.J.; Gill, E.K.A.","","2009","The process of developing a tool aiming for conceptual design of nano- and microsatellites is described. The various challenges and derived solutions are discussed. The final product offers systems engineers a fast way to analyze the feasibility of a particular design concept. The tool differs from existing tools in that it is specifically targeted at small satellites in the mass range of 1-50 kg. It is developed in Excel, and users interact with the tool in an intuitive manner through only one input and one output sheet. Required inputs include external interactions with the system such as payload, mission orbit, launcher and ground station. A set of design choices are implemented to guide users with different background knowledge. These choices have impact on the resulting satellite mass and power budgets, operating temperature envelope, attitude accuracy, propellant mass, received transmit power and data rate. Algorithms and scaling rules linking the input with the output parameters have been based on existing material, but have been revised and redefined based on an extensive satellite database containing about 200 satellites in the mass range of 0.1 – 50 kg, developed at TU Delft.","tool; scaling; design; nanosatellite; microsatellite","en","conference paper","Research School of Systems Engineering, Loughborough University","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:cca9be3a-b5c0-48a9-85e0-1ca91b2d76a5","http://resolver.tudelft.nl/uuid:cca9be3a-b5c0-48a9-85e0-1ca91b2d76a5","Design of a wind tunnel scale model of an adaptive wind turbine blade for active aerodynamic load control experiments","Hulskamp, A.W.; Beukers, A.; Bersee, H.E.N.; Van Wingerden, J.W.; Barlas, T.","","2007","Within wind energy research there is a drive towards the development of a “smart rotor”; a rotor of which the loading can be measured and controlled through the application of a sensor system, a control system and an aerodynamic device. Most promising solutions from an aerodynamic point of view are trailing edge flaps, either hinged or continuously deformable. An experiment was considered necessary in which the effectiveness of such a system, with the interaction between dynamics, aerodynamics and control was tested. In order to perform this experiment, a blade needed to be constructed that had the scaled dynamics of a full scale blade as well as sufficient actuation power and sensors for measurements as well as feedback control. A blade was designed and tested with sufficient strength for high wind speed as well as an eigenfrequency (12.5Hz) that was close to the initial value (19.2Hz), derived from scaling the dynamics. Finally adapting the airspeed set the right dynamics. System identification was performed and a controller designed with which a significant reduction in vibrations was attained.","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1dc55ce5-18c3-4986-b668-f70d9b24aac0","http://resolver.tudelft.nl/uuid:1dc55ce5-18c3-4986-b668-f70d9b24aac0","A Conceptual Design and Analysis Method for Conventional and Unconventional Airplanes","Elmendorp, R.J.M.; Vos, R.; La Rocca, G.","","2014","A design method is presented that has been implemented in a software program to investigate the merits of conventional and unconventional transport airplanes. Design and analysis methods are implemented in a design tool capable of creating a conceptual design based on a set of toplevel requirements. In contrast to established design methods, emphasis is placed on designing unconventional as well as conventional airplane configurations. A parametric fuselage primitive and a parametric lifting-surface primitive have been defined. By combining various instances of these primitives, airplane geometries ranging from blended-wing-body configurations to threesurface configurations can quickly be generated. Analysis methods have been developed/refined such as to enable the (physics-based) disciplinary analysis of conventional and unconventional airplane concepts. Design rules have been implemented to automatically size the main airplane components. This paper describes the workings of the software tool, presents relevant validation studies and showcases a comparison study between five different airplane configurations.","airplane design; multidisciplinary design optimization; knowledge-based engineering","en","conference paper","International Council of Aeronautical Sciences","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:96432477-6146-4f15-8601-a702404bb372","http://resolver.tudelft.nl/uuid:96432477-6146-4f15-8601-a702404bb372","Model based design of self-healing expandable coatings under different environmental conditions","Javierre, E.; Camanes, V.; Garcia Espallargas, S.J.; Van der Zwaag, S.; Garcia-Aznar, J.M.","","2013","A long-lasting barrier protection at damaged sites of coated system can be achieved by means of an active response of the primer. This may be attained through the release of reactive liquids from dispersed containers, the increase of the local mobility of the polymeric network, or the expansion of (dispersed elements in) the primer [1]. Such self-healing mechanisms provide an excellent strategy towards repeated and sustained self-repair properties and, additionally, are not incompatible with the inclusion of passive elements within the primer to produce a corrosion inhibition response. This work focuses on the modelling and simulation of expandable coatings resembling systems that contain thin clay-based interlayers [2]. However, a similar methodology could be applied to treat the hydraulic growth of inorganic grains in PPS coatings [3]. The expansion of a theoretical porous plastic primer is triggered by the ingress of environmental moisture. The volumetric growth of the primer into the crack is investigated under different humidity, temperature and atmospheric pressure conditions resembling different geographical locations (coastline vs. inland, changes in altitude and latitude, etc). Furthermore, the reversibility of the expansion process is investigated through hysteresis cycles resembling the change of the environmental conditions over a time lapse of several hours up to days. The self-sealing capacity of the coating is estimated from the maximum crack width that can be filled. A full characterization of self-sealing efficiency is given in terms of key design parameters such as porosity, permeability, sorption behaviour, swelling range, shear modulus, layers widths and adhesion properties.","barrier protection; gap filling; coating; modelling; prediction","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:a65cc340-cd5d-4907-a4a0-a2505bdf66a1","http://resolver.tudelft.nl/uuid:a65cc340-cd5d-4907-a4a0-a2505bdf66a1","Simulations with solution based mesh adaptation for fluid structure interactions","Sterenborg, J.J.H.M.; van Zuijlen, A.H.; Bijl, H.","","2008","","fluid structure interactions; unsteady solution based mesh adaptation; RANS","en","conference paper","European Academy of Wind Energy (EAWE)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3db971d6-22bb-4991-ac92-49c980afb44c","http://resolver.tudelft.nl/uuid:3db971d6-22bb-4991-ac92-49c980afb44c","Modeling Human Dynamics in Combined Ramp-Following and Disturbance-Rejection Tasks","Pool, D.M.; Van Paassen, M.M.; Mulder, M.","","2010","This paper investigates the modeling of humanmanual control behavior for pursuit tracking tasks in which target forcing functions consisting of multiple ramp-like changes in target attitude are used. Due to the use of a pursuit display and the predictability of such forcing function signals, it can be anticipated that a pursuit or precognitive control strategy, consisting of open-loop feedforward control inputs in response to the predictable reference signal, is applied by the human operator. If combined with an additional disturbance on the controlled element, a control task results that is similar to performing a commanded turn entry/exit or altitude capture in turbulence. It is as of yet uncertain if such pursuit or precognitive control is indeed used during such a control task, and to what extent a quasi-random disturbance would suppress pursuit/precognitive control strategies. A human-in-the-loop evaluation of the combined ramp-following and disturbance-rejection task was performed to gather data for the modeling of human manual control behavior. It is found that despite the anticipated pursuit and precognitive control inputs, classical compensatory models of human manual control dynamics are highly capable of describing human dynamics for these specific control tasks. Measured control inputs, however, are found to correspond well with proposed models for open-loop feedforward operations as well, suggesting future evaluation of a model of human behavior that combines, or switches between, error-reducing compensatory and open-loop feedforward operations.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:60b2b17c-41ce-460d-888a-ba556650d0e5","http://resolver.tudelft.nl/uuid:60b2b17c-41ce-460d-888a-ba556650d0e5","A multi-level environment to support demand driven design","Schut, E.J.; Van Tooren, M.J.L.","","2008","","","en","conference paper","Royal Aeronautical Society","","","","","","","","Aerospace Engineering","","","","",""
"uuid:eac7e0e3-0fe3-4171-882c-bd36517d0e46","http://resolver.tudelft.nl/uuid:eac7e0e3-0fe3-4171-882c-bd36517d0e46","Relative Orbital Element Estimation and Observability Analysis for Formation Flying Satellites using Inter-Satellite Range Measurements Only","Maessen, D.C.; Gill, E.K.A.","","2010","This paper investigates to what extent the relative orbital elements of two satellites flying in formation can be estimated making use of inter-satellite range measurements only. Since the determination of relative orbital elements does not require the orientation of the relative orbit with respect to absolute inertial space to be resolved, as would be the case for absolute orbital elements, the question arises whether relative range measurements alone can be sufficient to solve the problem of interest. Providing an answer to this question is both of academic and practical interest, especially for formation flying missions utilizing very small satellites that are limited in their capabilities. To this end, a linearized relative dynamics model is implemented using an iterative batch least-squares algorithm to estimate rectilinear relative positions and velocities, which are subsequently converted to relative orbital elements for a number of test cases. Furthermore, the observability of the system is analyzed to investigate which relative orbital elements are most observable.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:30ec0833-5559-4a58-87c2-d8392351c7e7","http://resolver.tudelft.nl/uuid:30ec0833-5559-4a58-87c2-d8392351c7e7","On parallel scalability aspects of strongly coupled partitioned fluid-structure-acoustics interaction","Blom, D.S.; Krupp, V.; Van Zuijlen, A.H.; Klimach, H.; Roller, S.; Bijl, H.","","2015","Multi-physics simulations, such as fluid-structure-acoustics interaction (FSA), require a high performance computing environment in order to perform the simulation in a reasonable amount of computation time. Currently used coupling methods use a staggered execution of the fluid and solid solver [6], which leads to inherent load imbalances. In [12] a new coupling scheme based on a quasi-Newton method is proposed for fluidstructure interaction which coupled the fluid and solid solver in parallel. The quasi-Newton method requires approximately the same number of coupling iterations per time step compared to a staggered coupling approach, resulting in a better load balance when running in a parallel environment. This contribution investigates the scalability limit and load-balancing for a strongly coupled fluid-structure interaction problem, and also for a fluid-structure-acoustics interaction problem. The acoustic far field of the fluid-structure-acoustics interaction problem is loosely coupled with the flow field.","fluid-structure-acoustics interaction; multi-physics; partitioned; parallel","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:8db01fd1-94d0-40d7-8e99-9385bd63b92e","http://resolver.tudelft.nl/uuid:8db01fd1-94d0-40d7-8e99-9385bd63b92e","New Method for Mesh Moving Based on Radial Basis Function Interpolation","De Boer, A.; Van der Schoot, M.S.; Bijl, H.","","2006","A new point-by-point mesh movement algorithm is developed for the deformation of unstructured grids. The method is based on using radial basis function, RBFs, to interpolate the displacements of the boundary nodes to the whole flow mesh. A small system of equations has to be solved, only involving the nodes on the boundary of the flow domain. Because no grid-connectivity information is needed, this method is very easy to implement, even for 3D applications. There are various RBFs available in literature that can be used for the new method. Therefore, the new algorithm is tested with several RBFs for a variety of problems to investigate which RBF produces the best meshes and which one is the most efficient. The method can handle large mesh deformations caused by translations, rotations and deformations of the boundary of the domain. However, the performance depends on the used RBF. The best accuracy and robustness are obtained with the thin plate spline. When efficiency is more important, a polynomial RBF with compact support is the best choice.","mesh deformation; unstructured meshes; radial basis function interpolation; fluid-structure interaction","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d084dc18-79b0-47bb-98c4-b10d9ca80ae5","http://resolver.tudelft.nl/uuid:d084dc18-79b0-47bb-98c4-b10d9ca80ae5","Automated Classification of Martian Morphology Using a Terrain Fingerprinting Method","Koenders, R.; Lindenbergh, R.C.; Zegers, T.E.","","2009","The planet Mars has a relatively short human exploration history, while the size of the scientific community studying Mars is also smaller than its Earth equivalent. On the other hand the interest in Mars is large, basically because it is the planet in the solar system most similar to Earth. Several satellites are currently orbiting Mars, and transmit data back in unprecedented detail. In fact, the Martian surface is mapped at up to 5 times higher resolution than the bottom of the ocean here on Earth. The scientific community studying Mars has already made great discoveries concerning, for example, the variability of the surface (Bibring, 2005), and the presence of water. To learn more about the history of the surface and about the planet as a whole, data generated by different satellite missions will have to be combined. Processing such large, multi-attribute datasets at a global Martian scale requires efficient automated classification methods. The use of automated classification in combination with geomorphometric data has only recently been possible on Mars with the creation of the global Mars Orbiter Laser Altimeter (MOLA) digital elevation model (DEM) (Smith et al. 2003), as obtained between 1997-2001 by the Mars Global Surveyor. (Bue and Stepinski, 2006) demonstrated the potential of classifying global MOLA DEM data and concluded that similar methodology could be applied on other data sets like the ~60m spatial resolution DEM, as currently under construction from High Resolution Stereo Camera (HRSC) images collected by ESA's Mars Express (Gwinner, 2007). On Earth, morphological classification has been used for numerous specific applications (Guzetti and Reichenbach, 1994; Hosokawa and Hoshi, 2001). Also only relatively recent it was demonstrated that attributes like gradient and roughness, as derived from elevation data, can be used to construct a multi-attribute feature vector, that, possibly in combination with other data, like intensity or multi-spectral data, can be consecutively applied in land surface and vegetation classification procedures (e.g. Antonorakis et al., 2008; Bork and Su, 2007; Chust et al., 2008). Even though the use of automated classification on Martian datasets has great potential, it is not yet being used as intensively by the scientific community studying Mars. The research presented in this abstract therefore formalises the methodology presented by Bue and Stepinski (2006) as the Terrain Fingerprinting Method (TFM) in Section 2. We have applied the TFM to several areas on Mars based on the MOLA DEM, which has a maximum spatial resolution of 400 meters per pixel; HRSC DEM, which has a maximum resolution of 50 meters per pixel; and a combination of the MOLA DEM with data from the Mars Express mineralogical spectrometer (OMEGA). The present abstract focuses on an analysis of the combination of OMEGA and MOLA DEM data as presented in Section 3.","","en","conference paper","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:032b908a-5396-4e33-b44d-4cb923a2dd01","http://resolver.tudelft.nl/uuid:032b908a-5396-4e33-b44d-4cb923a2dd01","Flow separation control by off surface elements","Veldhuis, L.L.M.; Van der Steen, M.","","2010","Comparative wind tunnel experiments were performed on passive flow separation control on a at plate model equipped with a flap. The purpose of these tests was to investigate the flow control capabilities of off-surface mounted elements. A comparison was made of delta-shaped vortex generators of 1 to 1/3 boundary layer height and cylinders close to the wall. Surface pressure as well as PIV measurements were performed to investigate the influence of the layout of the VGs as well as the diameter of the cylinder and the position of the elements. The results showed that the off-surface devices performed better than the on-surface VGs for the fully separated case, and were equally good in improving the state of boundary layer that is on the verge of separation. It was also found that the off-surface devices could be positioned over a wider range with respect to the separation point. The experiments furthermore indicated that for the optimum cylinder configuration the vortex shedding frequency was consistent with the frequencies found in literature on periodic flow excitation.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:5149f729-2c13-4207-b792-bdda36d0916c","http://resolver.tudelft.nl/uuid:5149f729-2c13-4207-b792-bdda36d0916c","Two level algorithms for partitioned fluid-structure interaction computations","Bijl, H.; Van Zuijlen, A.H.; Bosscher, S.","","2006","In this paper we use the multigrid algorithm - commonly used to improve the efficiency of the flow solver - to improve the efficiency of partitioned fluid-structure interaction iterations. Coupling not only the structure with the fine flow mesh, but also with the coarse flow mesh (often present due to the multigrid scheme) leads to a significant efficiency improvement. As solution of the flow equations typically takes much longer than the structure solve, and as multigrid is not standard in structure solvers, we do not coarsen the structure or the interface. As a result, the two level method can be easily implemented into existing solvers. Two types of two level algorithms were implemented: 1) Coarse grid correction of the partitioning error and 2) Coarse grid prediction or full multigrid to generate a better initial guess. The resulting schemes are combined with a fourth-order Runge-Kutta implicit time integration scheme. For the linear, one-dimensional piston problem with compressible flow the superior stability, accuracy and efficiency of the two level algorithms is shown. The parameters of the piston problem were chosen such that both a weak and a strong interaction case were obtained. Even the strong interaction case, with a flexible structure, could be solved with our new two level partitioned scheme with just one iteration on the fine grid. This is a major accomplishment as most weakly coupled methods fail in this case. Of the two algorithms the coarse grid prediction or full multigrid method was found to perform best. The resulting efficiency gain for our one-dimensional problem is around a factor of ten for the coarse to intermediate time steps at which the high order time integration methods should be run. For two- and three-dimensional problems the efficiency gain is expected to be even larger.","fluid-structure interaction; domain decomposition; partitioned coupling; multilevel techniques","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2da75f98-756a-4a71-a84f-35e1c72d3a9b","http://resolver.tudelft.nl/uuid:2da75f98-756a-4a71-a84f-35e1c72d3a9b","Noise computation for future urban air traffic systems","Arntzen, M.; Aalmoes, R.; Bussink, F.; Sunil, E.; Hoekstra, J.M.","","2015","The development of Personal aerial vehicles and unmanned aerial vehicles are expected to have a considerable influence on the development of future airspace design around large cities. In the Metropolis project, four different concepts for airspace design are assessed for a (metropolitan) city of the future. The different noise impact on the ground is addressed in this paper. The noise model is based on the maximum allowable source noise levels as proposed by the Federal Aviation Authority, as actual noise data from the considered aircraft is not available. Transmission loss has been modelled using Noise-Power-Distance relations from the Integrated Noise Model. The resulting noise model shows remarkable different noise footprints between the four concepts and between different traffic patterns, which included both converging and diverging flows. The layered airspace structure provided the lowest noise impact on the ground.","","en","conference paper","","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:24c4ab28-5f64-413e-9aca-a84f9bd27f28","http://resolver.tudelft.nl/uuid:24c4ab28-5f64-413e-9aca-a84f9bd27f28","Flow control of an oblique shock wave reflection with micro-ramp vortex generators: Effects of location and size","Giepman, R.H.M.; Schrijer, F.F.J.; Van Oudheusden, B.W.","","2013","The effects of micro-ramp height and location on a shock induced separation bubble were quantified using planar particle image velocimetry measurements. Conditional averaging was used to show that the amount of separation is related to the momentum flux in the near-wall region (< 0.5?) of the incoming boundary layer. The momentum flux added to this region scales linearly with micro-ramp height and larger microramps are shown to be more effective in stabilizing the interaction. Full boundary layer mixing is attained 5.? downstream of the micro-ramp and this forms a lower limit on the required distance between microramp and reflected shock foot.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:0e58be05-ebe8-4345-9d06-9addc8c86470","http://resolver.tudelft.nl/uuid:0e58be05-ebe8-4345-9d06-9addc8c86470","Structural monitoring of tunnels using terrestrial laser scanning","Lindenbergh, R.C.; Uchanski, L.; Bucksch, A.; Van Gosliga, R.","","2009","In recent years terrestrial laser scanning is rapidly evolving as a surveying technique for the monitoring of engineering objects like roof constructions, mines, dams, viaducts and tunnels. The advantage of laser scanning above traditional surveying methods is that it allows for the rapid acquisition of millions of scan points representing the whole surface of the object considered. Still it is a big challenge to obtain accuracies and precisions in the millimeter level when quantifying deformation of an object between epochs. This work presents two major steps towards obtaining sub noise level accuracies in surveying applications using terrestrial laser scan data. The first step aims at obtaining a point cloud of optimal quality for each epoch. The second steps consists of an adjustment and testing procedure that identifies deformation by gaining benefit from both data redundancy and individual point quality. The discussion of both steps is illustrated using several examples from mainly tunnel monitoring projects in the Rotterdam area.","","en","conference paper","Warsaw University of Technology","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:51e5d68e-83e1-404e-9527-1e9b9fcfea0f","http://resolver.tudelft.nl/uuid:51e5d68e-83e1-404e-9527-1e9b9fcfea0f","Aerodynamic force on a vawt in dynamic stall by integration of the velocity field from 3C particle image velocimetry","Simao Ferreira, C.J.; Scarano, F.; Van Kuik, G.A.M.; Van Bussel, G.J.W.","","2007","","","en","conference paper","European Academy for Wind Energy EAWE","","","","","","","","Aerospace Engineering","","","","",""
"uuid:74d0307d-416d-4a90-a06f-fe0f1a268906","http://resolver.tudelft.nl/uuid:74d0307d-416d-4a90-a06f-fe0f1a268906","Flight control and stability of a multiple kites tethered system","Podgaets, A.R.; Ockels, W.J.","","2006","One of novel concepts to use the energy of high altitude winds is by launching a series of kite on a long rope and let them pull the rope thus driving the generator. A mathematical model of tethered kites system has been developed consisting of models of kites and of the cable that links them together and to the generator on the ground energy station. The model described is then investigated for stability in various wind conditions including random wind gusts which require stochastic stability problem statement.","Laddermill; wind energy; kites; cable dynamics; stochastic stability","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:38325c08-9543-4fd3-a2e2-5d4223ce8d59","http://resolver.tudelft.nl/uuid:38325c08-9543-4fd3-a2e2-5d4223ce8d59","2.5D virtual reality visualisation of shearography strain data from a canvas painting","Groves, R.M.; Ameng, L.; Xiaoli, L.; Hackney, S.; Peng, X.; Osten, W.","","2009","Advanced measurement techniques for the structural diagnostics of artwork are increasingly providing more complex data that needs to be conveyed to conservators in a meaningful way. Holography and speckle interferometry based sensors are commonly used for this application and of these shearography is quite suitable for measurements outside the optics laboratory, due to the stability of using a common path interferometer configuration. Shearography provides noncontact full-field displacement gradient data on surface and sub-surface defects in the form of phase maps. The display of this data in the form of wrapped phase maps is only suitable for experienced users. A further image processing step generates unwrapped phase maps, which in an engineering environment are generally colour coded for display. For artwork measurement applications, the colour variation of the painting itself is important reference for the conservator to ocate defect locations. In this manuscript the displacement gradient data is presented as false height on the flat painting surface. A virtual reality viewer, freely downloadable from the internet, is used to display the data and allow the user to interact with it by rotating the object in virtual space. The effect is rather similar to viewing a raked light photograph, however with the advantage of remote or online viewing.","virtual reality; shearography; structural diagnostics; artwork","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","","","","",""
"uuid:18655662-1970-46fa-9f6f-258eac9f0921","http://resolver.tudelft.nl/uuid:18655662-1970-46fa-9f6f-258eac9f0921","A KBE genetic-causal cost modelling methodology for manufacturing cost contingency management","Curran, R.; Gilmour, M.; McAlleean, C.; Kelly, P.","","2009","The paper provides validated evidence of a robust methodology for the management of lean manufacturing cost contingency, with a particular focus on contingency regarding recurring work content. A truly concurrent engineering process is established by capturing a range of knowledge from the design, manufacturing and procurement functional areas, and analyzing it in a way that it can be automatically accessed with no specialist manufacturing knowledge, thus enabling the company to quickly estimate their designs based on the company’s lean manufacturing capability. A use-case study is presented which estimated the rolled-up assembly time for a thin-walled stiffened structure to be within ±7% of the manual estimating. A rolled-up accuracy of ± 10% was indicative in terms of total part and assembly cost, although it was evident that some of the individual cost deltas deviated more significantly, tending to cancel each other out in the roll-up. However, the key contribution of the paper is the implementation and validation of the use of the Genetic-Causal principle in developing a lean manufacture cost contingency methodology. Manufacturing cost models are established according to the principle of ‘causality’, which establishes which cost drivers should be used to generate the cost relations associated with the cost breakdown structure elements for various manufacturing processes. However, the ‘genetic’ principle is imposed through the hypothesis that the estimated costs of a new product will be similar to a company’s historical cost performance, relative to process selection, product definition and lean manufacturing capability. The latter use of the ‘genetic’ principle then presupposes that any new cost estimates generated are by nature not definitive and that rather one should be aiming to estimate the cost contingency. Consequently, the paper goes on to develop this hypothesis through a aircraft fuselage use-case to show how the lean concept idea of value added and non value added work content is consistent with this approach and indeed leads us to cost uncertainty and sensitivity analysis. Consequently, the paper advocates the formalization of an initially heuristic approach and so can be described inherently as a Knowledge Based Engineering (KBE) approach: capturing, structuring and formalizing manufacturing cost knowledge for application through knowledge bases and rules.","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6ef5c3fc-adb3-4fd0-9585-86e0a6319ef0","http://resolver.tudelft.nl/uuid:6ef5c3fc-adb3-4fd0-9585-86e0a6319ef0","Numerical simulation of hydraulic fracturing using a three-dimensional fracture model coupled with an adaptive mesh fluid model","Xiang, G.L.; Vire, A.; Pavlidis, D.; Pain, C.","","2015","A three-dimensional fracture model developed in the context of the combined finite-discrete element method is incorporated into a two-way fluid-solid coupling model. The fracture model is capable of simulating the whole fracturing process. It includes pre-peak hardening deformation, post-peak strain softening, transition from continuum to discontinuum, and the explicit interaction between discrete fracture surfaces, for both tensile and shear fracture initiation and propagation. The fluid-solid coupling model can simulate the interactions between moving fluids and multi-body solids. By incorporating the fracture model into the coupling model, a methodology of using the new coupling model to capture fracturing behaviour of solids in fluid-solid coupling simulations is proposed. To solve the problem in the coupling model of having adaptive continuous meshes being used by the fluid code and discontinuous meshes in the solid code, a scheme to convert different meshes is developed. A single fracture propagation driven by fluid pressures is simulated and the results show that the modelling obtains the correct critical load and propagation direction for fluid-driven fracturing. Several important phenomena, such as stress concentration ahead of the fracture tip, adaptive refinement of fluid mesh as a response to the fracture propagation and fluids flowing into fractures, are properly captured.","","en","conference paper","American Rock Mechanics Association ARMA","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:8bdb7be0-8c95-4eea-b34b-fc6bbc613960","http://resolver.tudelft.nl/uuid:8bdb7be0-8c95-4eea-b34b-fc6bbc613960","Adverse rotorcraft-pilot coupling: Prediction and suppression of rigid body RPC: Sketches from the work of Garteur HC-AG16","Pavel, M.D.; Götz, J.; Vu, B.; Jump, M.","","2008","","Pilot Induced Oscillations (PIO); Rigid Body Rotorcraft-Pilot Coupling (RPC); Flight control system (FCS)","en","conference paper","Royal Aeronautical Society","","","","","","","","Aerospace Engineering","","","","",""
"uuid:54f790c2-3a67-4275-ae1d-3d83d20f071c","http://resolver.tudelft.nl/uuid:54f790c2-3a67-4275-ae1d-3d83d20f071c","Force generation of bio-inspired hover kinematics","Vandenheede, R.B.R.; Bernal, L.P.; Morrison, C.L.; Humbert, S.","","2012","This paper presents the results of an experimental study of the aerodynamics of an elliptical flap plate wing in pitch-plunge motion. Several wing motion kinematics are derived from the kinematics of the Agrius Convolvuli (hawk moth) in hover. The experiments are conducted at a Reynolds number of 4, 800 and reduced frequency of 0.38, which are typical of the hawk moth flight. Three cases are reported: the hawk moth kinematics in which the elevation angle is ignored, the hawk moth kinematics with a correction to account for elevation angle effects, and a harmonic pitch-plunge kinematic of the same frequency and amplitude as the hawk moth kinematics. In all cases the wing pivots about the leading edge. The experiments are performed in The University of Michigan water channel. The wing model used has a Zimmerman planform shape with aspect ratio 3.87. Phase averaged force measurements are reported. Average thrust coefficients of 2.79, 2.64 and 2.39, respectively, are measured for the three cases. The measured peak thrust coefficients are 5.0, 4.8 and 6.1, respectively. The propulsion figure of merit in hover was also measured and found to be 0.47, 0.48 and 0.49 for the three cases. The flow evolution was measured using PIV. The results show formation of Leading Edge Vortices (LEV) and Trailing Edge Vortices (TEV) at different phases of the motion which depend on the particular kinematics. The relation between LEV and TEV vortex evolution and force generation is discussed.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:7c8ee2b9-735c-430d-bca1-8e5581b6f852","http://resolver.tudelft.nl/uuid:7c8ee2b9-735c-430d-bca1-8e5581b6f852","Aerodynamic Shape Optimization Using the Discrete Adjoint of the Navier-Stokes Equations: Applications towards Complex 3D Configurations","Brezillon, J.; Dwight, R.P.","","2009","Within the next few years, numerical shape optimization based on high fidelity methods is likely to play a strategic role in future aircraft design. In this context, suitable tools have to be developed for solving aerodynamic shape optimization problems, and the adjoint approach - which allows fast and accurate evaluations of the gradients with respect to the design parameters - is seen as a promising strategy. After describing the theory of the viscous discrete adjoint method and its implementation within the unstructured RANS solver TAU, this paper describes application for aerodynamic shape optimization. First wing and fuselage designs of the DLR-F6 wing-body aircraft are presented. A step forward in complexity is considered by applying the adjoint for flap and slat optimal settings of the DLR-F11 model, a wing-body aircraft in high-lift configuration. On all cases presented, optimization were successfully performed within a limited number of flows evaluations.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:a043ed21-cd8d-473d-8f63-e37b1cb45a8e","http://resolver.tudelft.nl/uuid:a043ed21-cd8d-473d-8f63-e37b1cb45a8e","Material Derivative Measurements in High-Speed Flows by Four-Pulse Tomographic PIV","Lynch, K.; Scarano, F.","","2013","A tomographic PIV system is introduced for the instantaneous measurement of the material derivative of velocity (VMD). The system is able to operate with very short temporal separation and is therefore suitable for applications in high-speed flows. The method of operation consists of the imaging of a measurement volume using an array of 12 CCD cameras and two double-cavity laser systems. Four independent recordings of particle images are captured by decomposing the system into three separate tomographic PIV systems comprised of four cameras. A discussion is made that compares the present working principle with other methods used to separate the light scattered from multiple pulses, namely by polarization. Various approaches are compared to determine the optimal utilization of four-pulse data to measure the VMD: the Eulerian and Lagrangian schemes are compared with the recently introduced fluid trajectory correlation (FTC) technique from the authors (Lynch and Scarano, 2013). The comparison focuses on the behavior of the schemes with respect to truncation errors and how the error estimates for four-pulse data are modified from those typically applied to image sequence data from a time-resolved PIV experiment. The analysis of synthetic images of a translating vortex clearly shows the envelope of applicability of the different schemes and the structure of the measurement errors introduced by truncation. The 12-camera tomographic system in four-pulse configuration is employed to measure the wake of an axisymmetric truncated base with an afterbody at a Reynolds number of 68,000. The system calibration accuracy and the baseline measurement uncertainty of the velocity are evaluated by performing a test with a negligible time delay between the independent tomographic PIV systems. The comparative performance of the material derivative schemes is estimated by appealing to a physical property of the material derivative field. The results indicate that a 12-camera system can be employed for material derivative evaluation using a variety of estimation schemes. Among these schemes, the FTC technique is found to be the least susceptible to the growth of truncation errors and is thus suitable for measurement at large temporal intervals which are necessary to suppress random errors.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:164d85ec-1683-48b0-bee5-2ef32e6aeefe","http://resolver.tudelft.nl/uuid:164d85ec-1683-48b0-bee5-2ef32e6aeefe","Decision-making for unmanned flight in icing conditions","Armanini, S.F.; Polak, M.; Gautrey, J.E.; Lucas, A.; Whidborne, J.F.","","2015","With the increased use of unmanned aerial systems (UAS) for civil and commercial applications, there is a strong demand for new regulations and technology that will eventually permit for the integration of UAS in unsegregated airspace. This requires new technology to ensure sufficient safety and a smooth integration process. The absence of a pilot on board a vehicle introduces new problems that do not arise in manned flight. One challenging and safety critical issue is flight in known icing conditions. Whereas in manned flight, dealing with icing is left to the pilot and his appraisal of the situation at hand, in unmanned flight this is no longer an option and new solutions are required. To address this, an icing-related decision-making system (IRDMS) is proposed. The system quantifies in-flight icing based on changes in aircraft performance and measurements of environmental properties, and evaluates what the effects on the aircraft are. Based on this, it determines whether the aircraft can proceed, and whether and which available icing protection systems should be activated. In this way, advice on an appropriate response is given to the operator on the ground, to ensure safe continuation of the flight and avoid possible accidents.","","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:257c9bd0-ab1f-4f24-863b-68c0b31ce386","http://resolver.tudelft.nl/uuid:257c9bd0-ab1f-4f24-863b-68c0b31ce386","On the use of Particle Image Velocimetry to predict trailing edge noise","Tuinstra, M.; Probsting, S.; Scarano, F.","","2013","The feasibility of aeroacoustic noise predictions based on Particle Image Velocimetry (PIV) measurements is studied. For this purpose, experiments are conducted on a sharp trailing edge (TE) flow developed along a flat plate at free stream velocity of 15m/s. The acoustic emissions were characterized in the NLR Small Anechoic Wind Tunnel (KAT) by means of microphone measurements. The result is used for benchmarking the PIV based noise predictions. PIV measurements were carried in a low-speed wind tunnel of TU Delft with similar properties to that of the KAT facility. Planar PIV measurements, performed at high spatial resolution, characterize the turbulent properties of the boundary layer travelling across the trailing edge. Time resolved Tomographic PIV measurements are obtained over a volume of 19.7mm x 9.1mm x 33.4mm at an acquisition rate of 12kHz. Two different approaches are compared for the prediction of TE noise based on PIV data. The first follows diffraction theory and requires the deduction of the instantaneous surface pressure fluctuations from PIV data. The second one relies on the integral solution of the Lighthill equation obtained through a tailored Green’s function for a semi-infinite half plane. This allows to calculate the scattered noise directly from the velocity data. The predictions based on diffraction theory agree well with the measured far field spectrum up to 4kHz. In contrast, the Green’s function approach yields a significant and systematic overprediction of approximately 12dB.","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:402dfdfd-bcb5-4638-b22d-c294fcec17b2","http://resolver.tudelft.nl/uuid:402dfdfd-bcb5-4638-b22d-c294fcec17b2","Resource-based view on the implementation of 6000 MW offshore wind power in the Netherlands","Mast, E.H.M.; Van Kuik, G.A.M.; Zaayer, M.B.","","2007","","","en","conference paper","European Wind Energy Agency EWEA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d80680d3-8950-4f84-86c0-0b4bde2a3b60","http://resolver.tudelft.nl/uuid:d80680d3-8950-4f84-86c0-0b4bde2a3b60","Self-healing metallopolymers: Detailed investigation of the self-healing properties by scratch testing","Bode, S.; Bose, R.K.; Sandmann, B.; Hager, M.D.; Garcia Espallargas, S.J.; Van der Zwaag, S.; Schubert, U.S.","","2013","In the last decade several intrinsic self-healing materials have been developed in which the healing mechanism was mainly based on the reversibility of a certain structural element. For this purpose, reversible covalent bonds, e.g., based on the Diels-Alder reaction or weaker non-covalent interactions, e.g., hydrogen bonding, ionic interactions or ?-? interactions, have been successfully utilized. In contrast, only few examples describe the self-healing of polymeric materials based on reversible metal-ligand-interactions, although this concept can be observed in nature (e.g., in mussel byssus threads). The directed interaction between a metal ion and corresponding ligands offers the possibility to integrate a reversible unit into a polymer matrix. If metal complexes are used as structural units to promote selfhealing, a compromise between the mechanical properties and the self-healing behavior must be found. Typically, the strength of the metal-ligand bond is the key factor for both. However, weaker metal complexes would promote the healing while, at the same time, the mechanical stability is reduced. The analysis of the self-healing capacity and the mechanical properties are central in order to design new functional materials. The terpyridine ligand was chosen as a model system to study the parameters for the resulting polymer properties. For this purpose, terpyridine containing polymers were synthesized and subsequently crosslinked with different metal salts, which offers the possibility to understand the influence of the crosslinking unit, the cation and the counterion. The resulting polymeric materials were investigated in detail (e.g., by scratch testing) to obtain a better insight into the self-healing behavior of the material.","metallopolymers; self-healing polymers; polymer testing; polymer coatings","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:14a35ea9-8f59-4e08-b458-22d78cc08c4e","http://resolver.tudelft.nl/uuid:14a35ea9-8f59-4e08-b458-22d78cc08c4e","The applicabillity of an adaptive human-machine interface in the cockpit","Abeloos, A.L.M.; Mulder, M.; Van Paassen, M.M.R.","","2000","","flight deck; adaptive interface; intelligent interface; automation; human factors","en","conference paper","European Communities","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2463ebfa-0fc9-4eb4-aaf7-8d9368535c83","http://resolver.tudelft.nl/uuid:2463ebfa-0fc9-4eb4-aaf7-8d9368535c83","Optic Flow Based State Estimation for an Indoor Micro Air Vehicle","Verveld, M.J.; Chu, Q.P.; De Wagter, C.; Mulder, J.A.","","2010","This work addresses the problem of indoor state estimation for autonomous flying vehicles with an optic flow approach. The paper discusses a sensor configuration using six optic flow sensors of the computer mouse type augmented by a three-axis accelerometer to estimate velocity, rotation, attitude and viewing distances. It is shown that the problem is locally observable for a moving vehicle. A Kalman filter is used to extract these states from the sensor data. The resulting approach is tested in a simulation environment evaluating the performance of three Kalman filter algorithms under various noise conditions. Finally, a prototype of the sensor hardware has been built and tested in a laboratory setup.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:7a1d441f-1128-4874-af40-d50089c99e89","http://resolver.tudelft.nl/uuid:7a1d441f-1128-4874-af40-d50089c99e89","Experimental and Numerical Investigation of the Effect of Rotor Blockage on Wake Expansion","Akay, B.; Simao Ferreira, C.J.; Van Bussel, G.J.W.; Tescione, G.","","2010","A detailed quantitative description of the aerodynamics of a horizontal axis wind turbine (HAWT) is difficult due to complexity of the flow field. Several methods from experimental to analytical are used to investigate the aerodynamics of a HAWT. In the present study, a wind tunnel experiment and computational fluid dynamics (CFD) simulations are used to explore the expansion of the wake. 2D actuator disc (AD) simulations are compared with the wind tunnel experiments. To understand the aerodynamic behavior of a model wind turbine blade, a detail flow field measurements in chordwise-spanwise directions and in the wake have been done. The measurements are performed on a 2 bladed rotor by means of Stereo Particle Image Velocimetry (Stereo PIV) in an open jet wind tunnel. In this paper, the velocity measurements performed in the wake region of the blade is presented. Actuator disc simulations are performed by applying a constant pressure jump on a permeable disc of zero thickness. Actuator disc simulations are carried out by using FLUENT 6.3.26 with the incompressible version of the Reynolds Averaged Navier-Stokes (RANS) equations. By validating the simulations with the experimental results, one may conclude that the unsteady CFD modeling works correctly and the wake expansion of the prescribed model is affected by the geometry of the Open Jet Facility (OJF).","","en","conference paper","European Wind Energy Association","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:454c5932-cab3-46ed-9387-f34150968f3b","http://resolver.tudelft.nl/uuid:454c5932-cab3-46ed-9387-f34150968f3b","Modeling, Simulation, and Testing of Surf Kites for Power Generation","Williams, P.; Lansdorp, B.; Ruiterkamp, R.; Ockels, W.J.","","2008","Non-powered flight vehicles such as kites can provide a means of transmitting wind energy from higher altitudes to the ground via tethers. At Delft University of Technology, construction and testing of such a high altitude wind machine is ongoing. The concept is called the Laddermill. It generates energy by pulling a line under high tension from a drum with a kite and retrieving it under low tension. The change in tension is achieved by changing the angle of attack and flight pattern of the kite. Although there is increased world wide interest for systems to extract wind energy from higher altitudes with kites, research into kite properties is limited. Such research however is required to enable the design of purpose-built kites for energy extraction. This paper presents testing of surf kites that was performed for model validation. Various models are discussed: a point model, a flexible multi-plate model and a rigid-body arc shaped model. Mathematical modeling and numerical simulations of the kite based on test data are presented.","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:9a0d7205-b0d4-441b-9259-bb36af079832","http://resolver.tudelft.nl/uuid:9a0d7205-b0d4-441b-9259-bb36af079832","Optical characterisation of complex structures, from engineering composites to bio-materials; abstract","Groves, R.M.","","2015","","","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:a0c368e2-8cc2-40c8-98cb-a6916ffc7589","http://resolver.tudelft.nl/uuid:a0c368e2-8cc2-40c8-98cb-a6916ffc7589","Constrained least-squares methods for partial differential equations","De Maerschalck, B.; Gerritsma, M.I.","","2006","Least-squares methods for partial differential equations are based on a norm-equivalence between the error norm and the residual norm. The resulting algebraic system of equations, which is symmetric positive definite, can also be obtained by solving a weighted collocation scheme using least-squares to solve the resulting algebraic equations. Furthermore, least-squares allows to ad extra constraints to the system. In the present work the entropy is added as an extra inequality constraint to ensure only physical solutions for the one-dimensional inviscid Burgers equation are obtained.","least-squares; spectral elements; space-time; entropy condition","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1b4ada74-4cb1-4b1a-b3b9-552c74c084ef","http://resolver.tudelft.nl/uuid:1b4ada74-4cb1-4b1a-b3b9-552c74c084ef","Icesat full waveform altimetry compared to airborne laser altimetry over the Netherlands","Duong, H.; Lindenbergh, R.; Pfeifer, N.; Vosselman, G.","","2007","Since 2003 the spaceborne laser altimetry system on board of NASA’s Ice, Cloud and land Elevation Satellite (ICESat) has acquired a large world-wide database of full waveform data organized in 15 products. In this research three products are evaluated over The Netherlands. For this purpose the raw full waveform product, the derived Gaussian decomposition product and the global land evaluation product are compared to laser data from the Dutch national airborne laser altimetry archive AHN. Using the CORINE land cover 2000 database allows us to compare ICESat to AHN elevation profiles with respect to the land cover classes forest, urban, bare land/low vegetation and water. This comparison shows that a large average height difference of 5.7 m occurs over forest, while much smaller differences of 1.24 m over urban areas, of 0.43 m over bare land/low vegetation and of 0.07 m over water are found. The reason for this large difference over forests is that the standard processing of NASA does not take the position of the last Gaussian mode of the waveform into account. Incorporating results from a full waveform processing procedure allows us to determine improved ICESat profiles. Comparing the improved profiles shows that the average difference with the AHN profiles over forest is reduced to -0.38 m, while the average differences for the other land cover classes do not exceed -0.75 m. Encountered limitations are discussed in the conclusions.","full waveform; DTM; AHN; laser altimetry; ICESat","en","conference paper","International Society for Photogrammetry and Remote Sensing","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:c006130a-c164-4abe-a7c5-313168485386","http://resolver.tudelft.nl/uuid:c006130a-c164-4abe-a7c5-313168485386","Optimization of Low-Thrust Earth-Moon Transfers Using Evolutionary Neurocontrol","Ohndorf, A.; Dachwald, B.; Gill, E.K.A.","","2009","Although low-thrust propulsion is an interesting option for scientific and reconnaissance missions to targets in planetary space, like the Moon, associated transfer strategies pose challenging requirements in terms of optimal control. The method of Evolutionary Neurocontrol (ENC), which has been applied very successfully to interplanetary low-thrust transfer problems, is now used for solving this type of steering problem. For exemplary validation, two low-thrust transfers from an Earth-bound geostationary transfer orbit into a Moon-bound orbit are optimized with respect to minimum flight time.","","en","conference paper","IEEE","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:b0e9bad2-04d2-419e-91cb-44fcba5da74b","http://resolver.tudelft.nl/uuid:b0e9bad2-04d2-419e-91cb-44fcba5da74b","Higher order time integration schemes for thermal coupling of flows and structures","Kazemi Kamyab, V.; Van Zuijlen, A.H.; Bijl, H.","","2011","The application of higher order implicit time integration schemes to conjugate heat transfer problems is analyzed with Dirichlet-Neumann as the decomposition method. In the literature, only up to second order implicit time integration schemes have been reported while there is a potential for gaining computational efficiency using higher orders. For loose coupling of the domains, the IMEX scheme consisting of the ESDIRK scheme for integrating the governing equations within the subdomains and an ERK scheme for explicit integration of the explicit coupling terms is utilized. The IMEX scheme is analyzed for two cases. In one, the material properties of the coupled domains are the same and in the other they are different. While for both cases, the IMEX scheme preserves the design order of the time integration scheme, different stability and accuracy properties are observed for the two. Finally, the computational efficiency of the higher order IMEX schemes relative to the second order scheme is demonstrated using a test case in 2-D involving coupled conduction problem of three domains.","higher order implicit time integration; IMEX; partitioned method; conjugate heat transfer","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:d6385d6e-5509-472e-8425-634481c0d340","http://resolver.tudelft.nl/uuid:d6385d6e-5509-472e-8425-634481c0d340","Integrated Design of a Long-Haul Commercial Aircraft Optimized for Formation Flying","Dijkers, H.P.A.; Van Nunen, R.; Bos, D.A.; Gutleb, T.L.M.; Herinckx, L.E.; Radfar, H.; Van Rompuy, E.; Sayin, S.E.; De Wit, J.; Beelaerts van Blokland, W.W.A.","","2011","The airline industry is under continuous pressure to reduce emissions and costs. This paper investigates the feasibility for commercial airlines to use formation flight to reduce emissions and fuel burn. To fly in formation, an aircraft needs to benefit from the wake vortices of the preceding aircraft. This requires a stable aerodynamic flow, accurate navigation and a highly sophisticated aircraft to counteract the negative consequences of flying in formation. It is found that the most stable region for an aircraft is between ten to twenty wingspans. For safety reasons the formation will fly in an echelon shape, indicating that only one wing of the aircraft is benefitting from the vortex. A GNSS/INS integrated navigation system is needed to allow for safe and accurate spacing between the aircraft. LiDAR based vortex detection is used to fly in the most stable and beneficial area of the vortex. Extra measures are taken to counteract the negative effects induced by flying with one wing in the vortex. A morphing wing is used to counteract the rolling moment due to an increase in lift on one wing. A strengthened tail is necessary to compensate the yaw moment induced by a reduction on drag on one wing. The benefits of formation flying in combination with the state-of-the-art open rotor jet could lead to fuel and emission savings of 54% compared to a Boeing 787. Implemented in 2030 this would be a major impact on the carbon footprint of the aviation industry.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:40cc44d5-fa76-4a9b-b209-123a7e1a549e","http://resolver.tudelft.nl/uuid:40cc44d5-fa76-4a9b-b209-123a7e1a549e","Validating BEM, Direct and Inverse Free Wake Models with the MEXICO Experiment","Micallef, D.; Kloosterman, M.; Ferreira, C.S.; Sant, T.; Van Bussel, G.J.W.","","2010","The primary objective of the MEXICO (Model Experiments in Controlled Conditions) project was to generate experimental data for validation of models for wind turbines. Kulite©pressure sensors were used for pressure measurements while Particle Image Velocimetry was used with the aim of tracking the tip vortex trajectory. The pressure measurements were carried out for both axial and yawed flow conditions with yaw angles of 15º; 30º and 45º. For the Particle Image Velocimetry measurements data was gathered for axial flow and for the ±30º yaw cases at a single tip speed ratio. In this work, an inverse free wake lifting line model, a direct free wake model and a BEM model are validated with the MEXICO data. Particular emphasis is placed on the study of yawed flow conditions. The inverse free-wake model makes use of the experimental loads as input in order to find the distribution of inductions and angle of attack. The predictive capability of BEM may therefore be assessed based on this. Validation of the inverse free-wake model was performed by investigating the stagnation pressureprediction as well as the vortex trajectory prediction. This was done by means of the PIV data gathered from the MEXICO experiment. This PIV data was also used for validation purposes of the direct free-wake model. The differences in the angle of attack distributions in yawed flow with these models was studied in order to assess the difference in results between the use of 2D and 3D airfoil data.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:1b00a247-ec72-42e2-b7dc-85d31e36833b","http://resolver.tudelft.nl/uuid:1b00a247-ec72-42e2-b7dc-85d31e36833b","Automated Control Surface Design and Sizing for the Prandtl Plane","Van Ginneken, D.A.J.; Voskuijl, M.; Van Tooren, M.J.L.; Frediani, A.","","2010","This paper presents a methodology for the design of the primary flight control surfaces, in terms of size, number and location, for fixed wing aircraft (conventional or unconventional). As test case, the methodology is applied to a 300 passenger variant of the Prandtl Plane. This box wing aircraft is deemed to have low induced drag compared to conventional aircraft. The methodology is completely physics based and includes an aerodynamic analysis, followed by a control allocation algorithm and an analysis of the flight mechanics. The design has to fulfill a set of handling qualities requirements with a minimum total control surface area. An optimization algorithm is used to find the best design. Results indicate that this is possible with ailerons outboard on both wings, elevators inboard on both wings and conventional rudders in the vertical tail. The configuration allows for pure torque control and also direct lift control in the longitudinal axis. These features can potentially enhance airfield performance.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:225874e4-dda6-47ce-b5f4-5983aacb5419","http://resolver.tudelft.nl/uuid:225874e4-dda6-47ce-b5f4-5983aacb5419","A two-parameter method for eN transition prediction","Van Ingen, J.L.; Kotsonis, M.","","2011","A correction to the eN method for transition prediction, that at present is in use at Delft University, is developed and tested. The existing method is based on solutions of the Falkner-Skan similar boundary layer equation without suction or blowing. The correction is based on additional solutions of this equation with suction and blowing. For the development of the method an Orr-Sommerfeld solver is used for the calculation of the stability diagrams for several series of Falkner-Skan ows with suction or blowing for fixed shape factor (H). This results in differences in the velocity profile curvature near the wall. A correction based on only one additional parameter has been devised using these results. A comparison between the corrected eN method and direct stability calculations for several non-similar ows with and without suction shows good agreement.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:1bc396bd-63b4-409a-92b8-0996be9ab50d","http://resolver.tudelft.nl/uuid:1bc396bd-63b4-409a-92b8-0996be9ab50d","Unsteady adaptive stochastic finite elements for aeroelastic systems with randomness","Witteveen, J.A.S.; Bijl, H.","","2008","","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:46c78763-255a-426f-a3d6-76467d0e8862","http://resolver.tudelft.nl/uuid:46c78763-255a-426f-a3d6-76467d0e8862","Tree crown delineation from high resolution airborne LiDAR based on densities of high points","Rahman, M.Z.A.; Gorte, B.G.H.","","2009","Tree detection and tree crown delineation from Airborne LiDAR has been focusing mostly on utilizing the canopy height model (CHM). This paper presents a method for individual tree crown delineation based on densities of high points (DHP) from the high resolution Airborne LiDAR. The DHP method relies on the fact that the density of received laser pulses above a certain height is high at the centre of a tree crown and decreases towards the edge of the crown. In this study, the performance of this method is compared to the CHM approach. The results demonstrate that tree delineation based on DHP is at least comparable to the CHM approach. The DHP based approach performs better compared to the CHM especially for trees with almost flat-top crown shape. However, post-processing on tree crown segments is still necessary to improve the overall accuracy of tree detection and tree crown delineation.","","en","conference paper","ISPRS","","","","","","","","Aerospace Engineering","","","","",""
"uuid:83cec40d-285c-437e-a7c8-01a200d9f6f5","http://resolver.tudelft.nl/uuid:83cec40d-285c-437e-a7c8-01a200d9f6f5","3D shape shearography with integrated structured light projection for strain inspection of curved objects","Anisimov, A.; Groves, R.M.","","2015","Shearography (speckle pattern shearing interferometry) is a non-destructive testing technique that provides full-field surface strain characterization. Although real-life objects especially in aerospace, transport or cultural heritage are not flat (e.g. aircraft leading edges or sculptures), their inspection with shearography is of interest for both hidden defect detection and material characterization. Accurate strain measuring of a highly curved or free form surface needs to be performed by combining inline object shape measuring and processing of shearography data in 3D. Previous research has not provided a general solution. This research is devoted to the practical questions of 3D shape shearography system development for surface strain characterization of curved objects. The complete procedure of calibration and data processing of a 3D shape shearography system with integrated structured light projector is presented. This includes an estimation of the actual shear distance and a sensitivity matrix correction within the system field of view. For the experimental part a 3D shape shearography system prototype was developed. It employs three spatially-distributed shearing cameras, with Michelson interferometers acting as the shearing devices, one illumination laser source and a structured light projector. The developed system performance was evaluated with a previously reported cylinder specimen (length 400 mm, external diameter 190 mmm) loaded by internal pressure. Further steps for the 3D shape shearography prototype and the technique development are also proposed.","3D shearography; shape shearography; multiple viewing shearography; strain mapping; structured light projection","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:23f6c40a-5756-4a46-bc3e-ee8727c9806a","http://resolver.tudelft.nl/uuid:23f6c40a-5756-4a46-bc3e-ee8727c9806a","Conceptual Design of the FAST-D Formation Flying Spacecraft","Maessen, D.C.; Guo, J.; Gill, E.; Gunter, B.; Chu, Q.P.; Bakker, G.; Laan, E.; Moon, S.; Kruijff, M.; Zheng, G.T.","","2009","The paper presents the latest results in the design of FAST-D, the Dutch micro-satellite for the Dutch–Chinese FAST (Formation for Atmospheric Science and Technology demonstration) formation flying mission. Over the course of the 2.5 year mission, the two satellites, FAST-D and FAST-T, will demonstrate various new technologies and perform observations of atmospheric aerosols and seasonal variations of height profiles in the cryosphere using spectropolarimeter and altimeter payloads on both spacecraft. A conceptual design for the Dutch spacecraft, FAST-D, is presented. Special focus is laid on the design of the attitude determination and control subsystem and on the space-based computing experiments to be performed on this spacecraft. Furthermore, new results in the development of the science payloads on FAST-D, the aerosol characterisation instrument SPEX (Spectropolarimeter for Planetary Exploration) and the altimeter SILAT (Stereo Imaging Laser Altimeter), are described. For SPEX, several design changes have been made to make the instrument more compatible with the FAST mission. For SILAT, an instrument re-design for Earth missions is presented, which results in considerable mass savings as compared to the earlier design.","FAST-D; ADCS; space-based computing; SPEX; SILAT","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:30c537eb-18ac-4441-89f5-6a393f60639c","http://resolver.tudelft.nl/uuid:30c537eb-18ac-4441-89f5-6a393f60639c","Active aeroelastic control aspects of an aircraft wing by using synthetic jet actuators: Modeling, simulations, experiments","Donnell, K.O.; Schober, S.; Stolk, M.; Marzocca, P.; De Breuker, R.; Abdalla, M.; Nicolini, E.; Gürdal, Z.","","2007","This paper discusses modeling, simulations and experimental aspects of active aeroelastic control on aircraft wings by using Synthetic Jet Actuators (SJAs). SJAs, a particular class of zero-net mass-flux actuators, have shown very promising results in numerous aeronautical applications, such as boundary layer control and delay of flow separation. A less recognized effect resulting from the SJAs is a momentum exchange that occurs with the flow, leading to a rearrangement of the streamlines around the airfoil modifying the aerodynamic loads. Discussions pertinent to the use of SJAs for flow and aeroelastic control and how these devices can be exploited for flutter suppression and for aerodynamic performances improvement are presented and conclusions are outlined.","synthetic jet actuators; aerodynamic modeling; active control; flutter","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerospace Structures","","","",""
"uuid:188b60e8-8aea-4798-9ecc-cb2773090aec","http://resolver.tudelft.nl/uuid:188b60e8-8aea-4798-9ecc-cb2773090aec","An introduction in the ecology of spatio-temporal affordances in airspace","Abeloos, A.L.M.; Mulder, M.; Van Paassen, R.M.M.","","2002","","affordances; alerting systems; aviation; cockpit display design; ecological interface design; ecological psychology","en","conference paper","University of Glasgow","","","","","","","","Aerospace Engineering","","","","",""
"uuid:65fe7e31-d22b-4463-a25b-823e54e4e2fb","http://resolver.tudelft.nl/uuid:65fe7e31-d22b-4463-a25b-823e54e4e2fb","Comparative analysis of automatic approaches to building detection from multi-source aerial data","Frontoni, E.; Khoshelham, K.; Nardinocchi, C.; Nedkov, S.; Zingaretti, P.","","2008","Automatic building detection has been a hot topic since the early 1990’s. Early approaches were based on a single aerial image. Detecting buildings is a difficult task so it can be more effective when multiple sources of information are obtained and fused. The objective of this paper is to provide a comparative analysis of automatic approaches to building detection from multi-source aerial images. We analysed data related to both urban and suburban areas and took into consideration both object based and pixel-based methods. Although many of these methods perform full data classification, we focused only on the detection of building regions. Three measures were used for the evaluation of the performance of each method: number of detected buildings to their total number (detection rate), number of objects wrongly detected as buildings (false positive) and number of missed buildings (false negative) to the number of detected buildings. The data sets we used were RGB and colour infrared (CIR) orthoimages and Digital Surface Models (DSMs) obtained by an airborne laser scanner, which provides a first pulse DSM and a last pulse DSM. In addition, we derived from these data and used other four sources of information: a Digital Terrain Model (DTM) obtained from a filtered version of the last pulse DSM, the height difference between the last pulse and the DTM, the height difference between the first and the last pulse and the Normalized Difference Vegetation Index (NVDI) derived from the red and infrared channels.We analysed results coming from three classification algorithms, namely Bayesian, Dempster-Shafer and AdaBoost, applied to the features extracted both at pixel level and at object level. To obtain a very realistic comparison we used the same training set for all methods, either pixel-based or object-based. Results obtained are interesting and can be synthesised in the need of fusing (the results of) more approaches to yield the best results.","building detection; comparative analysis; pixel-based and object-based algorithms; LIDAR; multispectral images","en","conference paper","International Society of Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:ea4d67c6-5cf3-437e-8aa0-5aa3d70f92a5","http://resolver.tudelft.nl/uuid:ea4d67c6-5cf3-437e-8aa0-5aa3d70f92a5","Determination of trim curves for a flapping-wing MAV","Armanini, S.F.; Verboom, J.L.; De Croon, G.C.H.E.; De Visser, C.C.","","2014","This paper presents the results of a series of flight tests conducted in order to assess the steady-state flight characteristics and basic control behaviour of the DelFly, a flapping-wing micro aerial vehicle (FWMAV). Flights were conducted in an indoor motion tracking facility and included steady-level flight at a range of different velocities and turn manoeuvres. A number of different trim points were determined and approximate trim curves constructed to describe elevator effectiveness. Aileron effectiveness was then evaluated in terms of resulting turn radii and turn rates. The results provide insight into some of the basic flight properties of the DelFly and represent a starting point for further modelling work. The flight testing process also highlighted some of the major issues to be addressed in order to obtain meaningful experimental results.","IMAV2014; MAV; Micro Air Vehicle; flapping wing; trim curves","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:00f65e8e-b32e-4478-95bd-69afc2eff95f","http://resolver.tudelft.nl/uuid:00f65e8e-b32e-4478-95bd-69afc2eff95f","Experimental Investigation of the Wind Turbine Blade Root Flow","Akay, B.; Ferreira, C.S.; Van Bussel, G.J.W.","","2010","Several methods from experimental to analytical are used to investigate the aerodynamics of a horizontal axis wind turbine. To understand 3D and rotational effects at the root region of a wind turbine blade, correct modeling of the flow field is essential. Aerodynamic models need to be validated by accurate experimental data. In this paper, the experimental results of the aerodynamic behavior of a model wind turbine blade, by focusing on the blade root flow, are presented. The measurements are performed on a 2 bladed rotor having 1 m radius by means of Stereo Particle Image Velocimetry in a wind tunnel. The spanwise velocity distribution on the suction side of the blade is determined in detail. It shows a complex flow pattern in the root region and positive spanwise flow component apparent at radial stations beyond r/R=0.4 at the leading edge (z/c=0.25).","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:f03c136d-58bf-4478-a74c-dbd41183c12f","http://resolver.tudelft.nl/uuid:f03c136d-58bf-4478-a74c-dbd41183c12f","CFD Analysis of Fuel Atomization, Secondary Droplet Breakup and Spray Dispersion in the Premix Duct of a LPP Combustor","Schmehl, R.; Maier, G.; Wittig, S.","","2000","The two phase flow in the premix duct of a LPP combustor is computed using a Lagrangian droplet tracking method. To reproduce the characteristic spray structure of an air-assisted pressure-swirl atomizer, a sheet spray model is de-rived from measured sheet parameters and combined with an advanced concept for modeling secondary atomization effects. The sheet spray model is used for the discretization of the initial sheet fragmentation, whereas modeling of droplet deformation and breakup during trajectory integration accounts for air-blast effects on size distribution and dispersion of the spray. Droplet drag increase due to subcritical deformation is approximated by a semi-empirical correlation. Breakup modeling addresses the three distinct mechanisms bag, multimode and shear breakup which are typically encountered in fuel-air mixing processes of combustion engines. The models include mechanism-dependent deformation and breakup times, correlations for drag increase as well as size and velocity distribution functions of droplet fragments. Results of the simulation are compared to Phase Doppler measurements of the spray providing local distributions of droplet sizes, velocities and size-dependent liquid volume flux.","combustor flow; fuel preparation; spray; two-phase flow","en","conference paper","ILASS","","","","","","","","Aerospace Engineering","AWEP","","","",""
"uuid:67297198-1399-47e2-80af-f05005f2e9db","http://resolver.tudelft.nl/uuid:67297198-1399-47e2-80af-f05005f2e9db","Determination of instantaneous pressure in a transonic base flow using four-pulse tomographic PIV","Blinde, P.L.; Lynch, K.P.; Schrijer, F.F.J.; Van Oudheusden, B.W.","","2015","A tomographic four-pulse PIV system is used in a transonic axisymmetric base flow experiment at a nominal free stream Mach number of 0.7, with the objective to obtain flow acceleration and pressure data. The PIV system, consisting of two double-pulse lasers and twelve cameras, allows acquiring two velocity fields with time separations as small as 2.5 ?s. A performance assessment is carried out and provides a typical average error estimate below 0.025 U? (0.3 voxel). The ability to use these velocity measurements to determine instantaneous, volumetric pressure distributions is assessed. To provide insitu validation, fast-response pressure transducers are used concurrent with the PIV measurements. PIV was found to yield a mean pressure profile with a similar shape as the mean pressure profile obtained with transducers and as reported in literature. The levels of pressure fluctuation were however found to be substantially higher. From this comparison it is concluded that the present PIV-based pressure determination procedure requires improvements to obtain more reliable pressure data. Such improvements may be obtained by optimizing the time separation between consecutive velocity fields and by making use of the temporal coherence between consecutive particle images through more advanced processing algorithms.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:9dc0f511-0ba5-4b4b-9591-9e34a49fc476","http://resolver.tudelft.nl/uuid:9dc0f511-0ba5-4b4b-9591-9e34a49fc476","Reliable Computational Predictions by Modeling Uncertainties Using Arbitrary Polynomial Chaos","Witteveen, J.A.S.; Bijl, H.","","2006","Inherent physical uncertainties can have a significant influence on computational predictions. It is therefore important to take physical uncertainties into account to obtain more reliable computational predictions. The Galerkin polynomial chaos method is a commonly applied uncertainty quantification method. However, the polynomial chaos expansion has some limitations. Firstly, the polynomial chaos expansion based on classical polynomials can achieve exponential convergence for a limited set of standard distributions only. Secondly, the application of polynomial chaos to nonlinearities can be difficult. These two limitations of the polynomial chaos expansion are discussed in this paper.","uncertainty quantification; polynomial chaos; orthogonal polynomials","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9efe77a6-21e9-4044-80c1-6a2467c7f579","http://resolver.tudelft.nl/uuid:9efe77a6-21e9-4044-80c1-6a2467c7f579","A high-precision position-based calibration table as the reference for angular accelerometer calibration experiment","Jatiningrum, D.; De Visser, C.C.; Van Paassen, M.M.; Mulder, M.","","2015","With the role of angular accelerometers in future fault-tolerant flight control systems, an in-depth evaluation of their performance then becomes a critical issue from the perspective of control system design. In this paper, a position-based calibration table is utilized to provide a sufficiently accurate angular acceleration reference in the dynamic angular calibration. However, the angular accelerometer measured data contains a high noise level when transmitted through the slip rings. To tackle this issue, a customized sensor Data Acquisition System (DAS) is designed. It is mounted on the turn-table top and has a direct access to the angular accelerometer data channel. To synchronize sensor and table data, two auxiliary signals are generated by the sensor DAS computer to help in the post measurement processing. The first signal is a regular pulse of 100 Hz, which is suitable to align sensor and table data. The second signal is a step function which acts as a data log trigger for the calibration table, as well as a marker of the record starting point. This approach results in a lower angular accelerometer noise level, below the specified limit of 3 mV. The ErrorRMS is 0:00195n, which after being calculated with the measurement results, evidently falls below the Gaussian probability density function specified by the standard of ±5:672. As a result, the customized setup enables a commercially available calibration table to serve as the reference for angular accelerometer calibration experiments.","","en","conference paper","","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:5d4e601b-4d38-4097-b5cc-d90eb8c59482","http://resolver.tudelft.nl/uuid:5d4e601b-4d38-4097-b5cc-d90eb8c59482","Analysis of biplane flapping flight with tail","Tay, W.B.; Bijl, H.; Van Oudheusden, B.W.","","2012","Numerical simulations have been performed to examine the interference effects between an upstream flapping biplane airfoil arrangement and a downstream stationary tail at a Reynolds number of 1000, which is around the regime of small flapping micro aerial vehicles. The objective is to investigate the effect of the relative distance and angle of attack between the airfoils and its tail on the overall propulsive efficiency, thrust and lift. An immersed boundary method Navier-Stokes solver is used for the simulation. Results show that overall efficiency and average thrust per airfoil can be increased up to 17% and 126% respectively when the top and bottom airfoils come into contact during flapping. When placing the tail at a strategic position, the overall configuration generates much higher lift, although at the expense of decreased efficiency and thrust. Increasing the angle of attack of the tail also helps to increase the lift. Analysis of the vorticity plots reveals the interaction between the vortices and the airfoils and the reason behind the high thrust and lift. The results obtained from this study can be used to optimize the performance of small flapping MAVs.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:576b57d4-48d4-4f1e-88fb-5240cafda5eb","http://resolver.tudelft.nl/uuid:576b57d4-48d4-4f1e-88fb-5240cafda5eb","Electrochemical healing of MAX phase ceramics (abstract)","Abdelkader, A.M.; Garcia Espallargas, S.J.; Van der Zwaag, S.","","2011","","MAX phase ceramic; self healing; scratch","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:166e767c-535e-4a75-8b74-f4ed4712c078","http://resolver.tudelft.nl/uuid:166e767c-535e-4a75-8b74-f4ed4712c078","Near-Hover Flapping Wing MAV Aerodynamic Modelling: A linear model approach","Caetano, J.V.; Verboom, J.; De Visser, C.C.; De Croon, G.C.H.E.; Remes, B.D.W.; De Wagter, C.; Mulder, M.","","2013","","","en","conference paper","","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:2cc80325-5122-4cb9-bbb1-9f1e6f65afa4","http://resolver.tudelft.nl/uuid:2cc80325-5122-4cb9-bbb1-9f1e6f65afa4","Real-time Wind Profile Estimation using Airborne Sensors","In 't Veld, A.C.; De Jong, P.M.A.; Van Paassen, M.M.; Mulder, M.","","2011","Wind is one of the major contributors to uncertainty in continuous descent approach operations. Especially when aircraft that are flying low or idle thrust approaches are issued a required time of arrival over the runway threshold, as is foreseen in some of the future ATC scenarios, the on-board availability of both dependable and accurate wind estimates becomes a necessity. This paper presents a method for real-time estimation of a wind profile in the terminal maneuvering area, based on data transmissions of nearby aircraft that produces real-time wind profile estimates in a form that is usable for accurate trajectory estimation. The wind estimation algorithm is designed to process data that is of the form currently used in the Aircraft Meteorological Data Relay (AMDAR)-program. The algorithm combines a stochastic estimation based on this data and a traditional logarithmic estimator in order to be able to produce a valid estimation even when there are no data available from other aircraft.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:433a0dd7-c2fd-4b14-a2eb-f02e5862bf13","http://resolver.tudelft.nl/uuid:433a0dd7-c2fd-4b14-a2eb-f02e5862bf13","The ERTMS railway signaling system: Deals on wheels? An inquiry into the safety architecture of high speed train safety","Stoop, J.A.A.M.; Dekker, S.","","2008","","","en","conference paper","Mines Pris, Les presses, Collection Science Economiques","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b308a441-5f2d-48b8-9130-89210fb87ce2","http://resolver.tudelft.nl/uuid:b308a441-5f2d-48b8-9130-89210fb87ce2","Uncertainty multidisciplinary design optimization of space systems in the presence of new attributes","Guo, J.; Yao, W.; Gill, E.K.A.","","2010","The problem of new attributes and the induced uncertainties has been extensively discussed in this paper. The methodology of uncertainty multidisciplinary design optimization has also been extended to spacecraft conceptual design in the presence of new attributes. The application of this methodology on fractionated spacecraft indicates that the proposed method is able to provide useful information under uncertainties induced by new attributes.","","en","conference paper","International Astronautical Federation","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:b0501da0-a5fc-42e8-9407-5864f30d49bd","http://resolver.tudelft.nl/uuid:b0501da0-a5fc-42e8-9407-5864f30d49bd","Pressure adaptive honeycomb: A new adaptive structure for aerospace applications","Vos, R.; Barrett, R.","","2010","A new type of adaptive structure is presented that relies on pressurized honeycomb cells that extent a significant length with respect to the plane of the hexagons. By varying the pressure inside each of the cells, the stiffness can be altered. A variable stiffness in combination with an externally applied force field results in a fully embedded pressure adaptive actuator that can yield strains well beyond the state-of-the-art in adaptive materials. The stiffness change as a function of the pressure is modeled by assigning an equivalent material stiffness to the honeycomb walls that accounts for both the inherent material stiffness as the pressure-induced stiffness. A finite element analysis of a beam structure that relies on this model is shown to correlate well to experimental results of a three-point bend test. To demonstrate the concept of embedded pressure adaptive honeycomb, an wind tunnel test article with adaptive flap has been constructed and tested in a low speed wind tunnel. It has been proven that by varying the cell pressure the flap changed its geometry and subsequently altered the lift coefficient.","pressure, adaptive, honeycomb, morphing, aircraft, pneumatic, inflatable","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerospace Structures & Design Methodology","","","",""
"uuid:ed354c6b-c3e0-44c6-95b0-3cc5ab527b95","http://resolver.tudelft.nl/uuid:ed354c6b-c3e0-44c6-95b0-3cc5ab527b95","Educating engineering practice in six design projects in a row","Kamp, A.","","2013","Tomorrow’s engineers are required to have a good balance between deep working knowledge of engineering sciences and engineering skills. In the Bachelor in Aerospace Engineering at TU Delft, students are educated to master these competences so that they are ready to engineer when they graduate. The bachelor curriculum has three mainstreams of about equal study load: Aerospace Design, Aerospace Engineering & Technology, and Basic Engineering Sciences. The Aerospace Design stream is built up semester after semester of a design project and an accompanying design course. The main objectives of the design projects are related to contextual learning, learning by doing together, and learning and practicing academic and engineering skills, and being a mental organiser for the students. Over the years of study the design projects increase in complexity and openness, from knowing to application and synthesis, from tangible to abstract, from monoto multidisciplinary, and from mostly individual to team work. All projects exploit the factors that promote intrinsic motivation (challenge, curiosity, control, fantasy, competition, cooperation, and recognition). To assure that the intrinsic motivation factors and the semester themes are well addressed, each design project is characterised by a storyline, professional role, client, real-life problem, engineering process, and certain attainment levels of engineering skills. The projects make use of student project spaces in a dedicated building for collaborative learning, and laboratories like wind tunnels, a structures and materials laboratory, a study collection of aircraft and spacecraft parts and subsystems, and a flight simulator.","project education; project-based learning; experiential learning; aerospace engineering; design education; integrated curriculum; intrinsic motivation","en","conference paper","MIT & Harvard University","","","","","","","","Aerospace Engineering","Support Aerospace Engineering","","","",""
"uuid:f67255b7-5ad8-4725-ad19-66b6b345347b","http://resolver.tudelft.nl/uuid:f67255b7-5ad8-4725-ad19-66b6b345347b","Impact of Higher Fidelity Models on Simulation of Active Aerodynamic Load Control For Fatigue Damage Reduction","Resor, B.; Wilson, D.; Berg, D.; Berg, J.; Barlas, T.; Van Wingerden, J.W.; Van Kuik, G.A.M.","","2010","Active aerodynamic load control of wind turbine blades is being investigated by the wind energy research community and shows great promise, especially for reduction of turbine fatigue damage in blades and nearby components. For much of this work, full system aeroelastic codes have been used to simulate the operation of the actively controlled rotors. Research activities in this area continually push the limits of the models and assumptions within the codes. This paper demonstrates capabilities of a full system aeroelastic code recently developed by researchers at the Delft University Wind Energy Research Institute with the intent to provide a capability to serve the active aerodynamic control research effort, The code, called DU_SWAMP, includes higher fidelity structural models and unsteady aerodynamics effects which represent improvement over capabilities used previously by researchers at Sandia National Laboratories. The work represented by this paper includes model verification comparisons between a standard wind industry code, FAST, and DU_SWAMP. Finally, two different types of active aerodynamic control approaches are implemented in order to demonstrate the fidelity simulation capability of the new code.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:24bebec3-b04e-43d0-b852-db6f0f3b53ae","http://resolver.tudelft.nl/uuid:24bebec3-b04e-43d0-b852-db6f0f3b53ae","Feasibility analysis of achieving a stabilized approach","Heiligers, M.M.; Van Holten, T.; Mulder, M.","","2008","","Approach; Stabilized Approach; Pilot; Task Demand Load; RNAV","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c2fb8e60-8b4e-446f-8535-c41372a3a9da","http://resolver.tudelft.nl/uuid:c2fb8e60-8b4e-446f-8535-c41372a3a9da","Multiscale Methods in Computational Fluid and Solid Mechanics","De Borst, R.; Hulshoff, S.J.; Lenz, S.; Munts, E.A.; Van Brummelen, E.H.; Wall, W.A.","","2006","The basic idea of multiscale methods, namely the decomposition of a problem into a coarse scale and a fine scale, has in an intuitive manner been used in engineering for many decades, if not for centuries. Also in computational science, large-scale problems have been solved, and local data, for instance displacements, forces or velocities, have been used as boundary conditions for the resolution of more detail in a part of the problem. Recent years have witnessed the development of multiscale methods in computational science, which strive at coupling fine scales and coarse scales in a more systematic manner. Having made a rigorous decomposition of the problem into fine scales and coarse scales, various approaches exist, which essentially only differ in how to couple the fine scales to the coarse scale. The Variational Multiscale Method is a most promising member of this family, but for instance, multigrid methods can also be classified as multiscale methods. The same conjecture can be substantiated for hp-adaptive methods. In this lecture we will give a succinct taxonomy of various multiscale methods. Next, we will briefly review the Variational Multiscale Method and we will propose a space-time VMS formulation for the compressible Navier-Stokes equations. The spatial discretization corresponds to a high-order continuous Galerkin method, which due to its hierarchical nature provides a natural framework for `a priori' scale separation. The latter property is crucial. The method is formulated to support both continuous and discontinuous discretizations in time. Results will be presented from the application of the method to the computation of turbulent channel flow. Finally, multigrid methods will be applied to fluid-structure interaction problems. The basic iterative method for fluid-structure interaction problems employs defect correction. The latter provides a suitable smoother for a multigrid process, although in itself the associated subiteration process converges slowly. Indeed, the smoothed error can be represented accurately on a coarse mesh, which results in an effective coarse-grid correction. It is noted that an efficient solution strategy is made possible by virtue of the relative compactness of the displacement-to-pressure operator in the fluid-structure interaction problem. This relative compactness manifests the difference in length and time scales in the fluid and the structure and, in this sense, the multigrid method exploits the inherent multiscale character of fluid-structure-interaction problems.","multiscale methods; fluid flow; turbulence; fluid-structure interaction; multigrid methods","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3103f026-5d7a-44c2-8b89-18cdf56eafbc","http://resolver.tudelft.nl/uuid:3103f026-5d7a-44c2-8b89-18cdf56eafbc","Experimental investigation of the instantaneous spatial flow organization of high-speed boundary layers","Humble, R.A.; Elsinga, G.E.; Scarano, F.; van Oudheusden, B.W.","","2008","","","en","conference paper","Delft University of Technoloy / EWA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4576de3b-b405-475c-9fcf-5404599e61a3","http://resolver.tudelft.nl/uuid:4576de3b-b405-475c-9fcf-5404599e61a3","Flux and polarization signals of spatially inhomogeneous gaseous exoplanets","Karalidi,, T.; Stam, D.M.; Guirado, D.","","2013","Aims. We present numerically calculated, disk-integrated, spectropolarimetric signals of starlight that is reflected by vertically and horizontally inhomogeneous gaseous exoplanets. We include various spatial features that are present on Solar System’s gaseous planets: belts and zones, cyclonic spots, and polar hazes, to test whether such features leave traces in the disk-integrated fux and polarization signals. Methods. Broadband flux and polarization signals of starlight that is reflected by gaseous exoplanets are calculated using an efficient, adding-doubling radiative transfer code, that fully includes single and multiple scattering and polarization. The planetary model atmospheres are vertically inhomogeneous and can be horizontally inhomogeneous, and contain gas molecules and/or cloud and/or aerosol particles. Results. The broadband flux and polarization signals are sensitive to cloud top pressures, although in the presence of local pressure differences, such as in belts and clouds, the flux and polarization phase functions have similar shapes as those of horizontally homogeneous planets. Fitting flux phase functions of a planet with belts and zones using a horizontally homogeneous planet could theoretically yield cloud top pressures that differ by a few hundred mbar from those derived from fitting polarization phase functions. In practice, however, observational errors and uncertainties in cloud properties would make such a fit unreliable. A cyclonic spot like Jupiter’s Great Red Spot, covering a few percent of the disk, located in equatorial regions, and rotating in and out of the observer’s view yields a temporal variation of a few percent in the broadband flux and a few percent in the degree of polarization. Polar hazes leave strong traces in the polarization of reflected starlight in spatially resolved observations, especially seen at phase angles near 90°. Integrated across the planetary disk, polar hazes that cover only part of the planetary disk, change the broadband degree of polarization of the reflected light by a few percent. Such hazes have only small effects on locally reflected broadband fluxes and negligible effects on disk-integrated broadband fluxes. Conclusions. Deriving the presence of belts and zones in the atmospheres of gaseous exoplanets from broadband flux and polarization observations will be extremely difficult. Cyclonic spots could leave temporal changes in the broadband flux and polarization signals of a few percent. Polar hazes that cover a fraction of the planetary disk, and that are composed of small, Rayleigh scattering particles, change the broadband degree of polarization by at most a few percent.","methods; numerical / planets and satellites; atmospheres / polarization","en","conference paper","EDP Sciences","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:5523f9b3-f0ea-4695-a5b2-842783d398d4","http://resolver.tudelft.nl/uuid:5523f9b3-f0ea-4695-a5b2-842783d398d4","Adverse rotorcraft-pilot coupling: The construction of the test campaigns at the University of Liverpool","Jump, M.; Hodge, S.; Dang Vu, B.; Masarati, G.; Quaranta, G.; Mattaboni, M.; Pavel, M.D.; Dieterich, O.","","2008","","","en","conference paper","Royal Aeronautical Society","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b5e3e6e0-4774-4fbd-b357-1a735dcc183d","http://resolver.tudelft.nl/uuid:b5e3e6e0-4774-4fbd-b357-1a735dcc183d","A New Structural Design Concept for Blended Wing Body Cabins","Vos, R.; Geuskens, F.J.J.M.M.; Hoogreef, M.F.M.","","2012","This paper outlines a new concept for a pressure cabin design for blended-wing-body aircraft. An overview is presented of the wide oval cabin and why it is believed to be a possible alternative to existing designs of non-circular pressurized cabins. The perimeter of the oval cross section is formed by four smoothly connecting arcs of different radii. One arc forms the upper surface of the fuselage, one arc forms the lower surface, and two arcs at either side form the side of the fuselage. At the interconnection nodes of each of the arcs a prismatic box structure caries the tension and compression loads that result from pressurization. This structural layout forms a large uninterrupted internal space that allows for a flexible cabin configuration. Furthermore, this concept encompasses synergy in aerodynamic and structural design by having the lower member of the prismatic box structure forming the passenger floor and having the cabin outer skin panels be directly part of the aerodynamic shell. A method has been developed that estimates the weight of the cabin based on pressurization loads and main geometrical parameters of the cabin (height, span distribution, and length) as well as the geometry of the airfoil in the plane of symmetry of the cabin. A cabin design for 400 passengers shows a total cabin weight of 34 metric tons, and sufficient cargo volume for 36 LD3 containers.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:e718a447-b19e-44c8-ae32-bd73fa58eff2","http://resolver.tudelft.nl/uuid:e718a447-b19e-44c8-ae32-bd73fa58eff2","Vortex wake investigation behind a wing-flap model with jet simulations","Veldhuis, L.L.M.; De Kat, R.","","2008","To get a better insight in the effect of jets on vortex development and decay, stereo-PIV measurements were performed in a towing tank behind a flapped aircraft model. The experimental data set yields the wake vortex behavior in a range that extends from the vortex formation stage up to the mid-field (approximately t* =2 corresponding to 100 wingspans for a = 0º and 60 wingspans for a=6º). Although the jet does not affect the overall circulation strength, it has a significant effect on the velocity distribution in the wake. A new Double Gaussian vortex model is introduced that perfectly fits the measurement data.","vortex wakes; jets; vortex modeling","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:cbc70978-62cd-44cb-822d-419387427efa","http://resolver.tudelft.nl/uuid:cbc70978-62cd-44cb-822d-419387427efa","Making curricular change: Case report of a radical reconstruction proces","Kamp, A.; Klaassen, R.","","2013","Educational change is technically relatively simple but socially complex. Making effective change in engineering curricula is problematic and often fails by too high ambitions, too short development time frames, inconsistent design and a lack of a systems approach, but also by poor leadership, lack of ownership and low faculty engagement. Literature tells that typically only 30% of the original objectives of an intended curriculum change are achieved in the as-built programme. In the period 2006-2010 TU Delft Faculty of Aerospace Engineering has reestablished the profile of the bachelor and made a radical reconstruction by recalibrating the content and introducing a state-of-the-art active teaching approach. The innovative bachelor educates tomorrow’s engineers in the context of conception, design, implementation and operation of aircraft and spacecraft systems and processes. The paper gives an inside look in the reconstruction process. It shows that curriculum change is engineering and not science; it is politics and not always rational. The paper starts with an update of the educational vision that resulted in the prime objectives of change. It follows the systems approach with the student as the user and co-producer of the education always in mind. It addresses the design and development plan of the reconstruction, its organisation and leadership, and the role of upper management. They change over time and depend on the phase of development.","educational change; curricular change; education reform; change process; colour-thinking","en","conference paper","CDIO","","","","","","","","Aerospace Engineering","Support Aerospace Engineering","","","",""
"uuid:ec9e7226-d011-46bb-9f8a-6be259306e60","http://resolver.tudelft.nl/uuid:ec9e7226-d011-46bb-9f8a-6be259306e60","Value chain innovation processes and the influence of co-innovation","Beelaerts van Blokland, W.W.A.; Santema, S.C.","","2006","","","en","conference paper","IMP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:965082d0-fbbf-4056-9d08-40348a17965c","http://resolver.tudelft.nl/uuid:965082d0-fbbf-4056-9d08-40348a17965c","Integer ambiguity resolution with nonlinear geometrical constraints","Giorgi, G.; Teunissen, P.J.G.; Verhagen, S.; Buist, P.J.","","2009","Integer ambiguity resolution is the key to obtain very accurate positioning solutions out of the GNSS observations. The Integer Least Squares (ILS) principle, a derivation of the least-squares principle applied to a linear system of equations in which some of the unknowns are subject to an integer constraint,was demonstrated to be optimal among the class of admissible integer estimators. In this contribution it is shown how to embed into the functional model a set of nonlinear geometrical constraints, which arise when considering a set of antennae mounted on a rigid platform. A method to solve for the new model is presented and tested: it is shown that the strengthened underlying model leads to an improved capacity of fixing the correct integer ambiguities.","constrained methods; GNSS; integer ambiguity resolution","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:4902bf34-4087-46d0-974c-bce8d1720239","http://resolver.tudelft.nl/uuid:4902bf34-4087-46d0-974c-bce8d1720239","Keys to success with knowledge-based techniques","Cooper, D.J.; Van Tooren, M.J.L.; Wan Mohamed, M.","","2008","","","en","conference paper","SAE International","","","","","","","","Aerospace Engineering","","","","",""
"uuid:45d4b53c-19ed-4d17-baff-d5aa98b55e9b","http://resolver.tudelft.nl/uuid:45d4b53c-19ed-4d17-baff-d5aa98b55e9b","Deterministic Price Setting Rules to Guarantee Profitability of Unbundling in the Airline Industry","Van Diepen, G.; Curran, R.","","2011","Unbundling the traditional airfare is one of the airline industry’s practices to generate ancillary revenue in its struggle for profitability. However, unbundling might just as well negatively affect profit. In this paper deterministic price setting rules are established to guarantee profitability of unbundling irrespective of what product is unbundled. By comparing unbundling to a conventional price change, the least profitable scenarios of unbundling can be solved using the economic principle of price elasticity. The solution can be optimized dichotomously for profitability – profit guaranteed versus not guaranteed – by setting the unbundled prices such that the least profitable scenarios would still be profitable; profitability would then be guaranteed for any other scenario. The price setting rules this method renders are incorporated in a decision tree model and corresponding procedure for airline managers. As opposed to what customer research can produce, the model and corresponding procedure are generally applicable.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:60428bab-62f3-42be-b4d3-513f121d1f84","http://resolver.tudelft.nl/uuid:60428bab-62f3-42be-b4d3-513f121d1f84","Context-dependent ATC complexity metric","Mercado Velasco, G.A.; Borst, C.","","2015","Several studies have investigated Air Traffic Control (ATC) complexity metrics in a search for a metric that could best capture workload. These studies have shown how daunting the search for a universal workload metric (one that could be applied in different contexts: sectors, traffic patterns, controllers, or ATC tasks) can be. We propose that complexity metrics should be tailor made to the task they were meant to be used for, and focus in the elicitation of parameters that could best capture complexity of the task at hand. For the ATC task of rerouting aircraft a selection of relevant context parameters was made, and based on these a new complexity metric called SSD Composite is proposed. The metric is based on the Solution Space Diagram (SSD) concept. As a pilot study, a low fidelity simulation in which ATM experts operated as controllers and provided self assessments of workload was conducted. Data obtained from the simulation runs was used to compare traditional metrics (Traffic Load and NASA/FAA’s Dynamic Density) against the SSD Composite metric by means of mixed-effects linear regressions. Results showed that SSD-based metrics were much less sensitive to sector or traffic pattern effects and that the amount of observed workload variation accounted for by the SSD Composite fixed effects was higher than that of the Dynamic Density metric.","","en","conference paper","CEAS","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:9b2d6d72-36d4-4e6e-bd48-a9e9146249fe","http://resolver.tudelft.nl/uuid:9b2d6d72-36d4-4e6e-bd48-a9e9146249fe","Large-scale tomo-PIV for on-site drag analysis in speed sports","Terra, W.; Sciacchitano, A.; Scarano, F.","","2015","Large-scale tomographic Particle Image Velocimetry is proposed as a tool for the on-site aerodynamic investigation in speed sports. The ring-of-fire concept is presented, which relies upon a tomographic PIV system used during the training of athletes in speed sports. The system consists of a short tunnel installed in a velodrome, through which the athletes pass during their training. Helium-filled soap bubbles are used as flow tracers and images are recorded via high-speed digital cameras. The ring-of-fire concept allows measuring the airflow around athletes, and is suitable for aerodynamic investigation and drag minimization. The present study proves the feasibility of the concept by showing its working principle on small scale on the flow over a sphere","","en","conference paper","University of Poitiers","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:730597cd-cf1a-493f-97b1-fa903d4e4c0e","http://resolver.tudelft.nl/uuid:730597cd-cf1a-493f-97b1-fa903d4e4c0e","Adaptive Optimizing Nonlinear Control Design for an Over-actuated Aircraft Model","Van Oort, E.R.; Sonneveldt, L.; Chu, Q.P.; Mulder, J.A.","","2011","In this paper nonlinear adaptive flight control laws based on the backstepping approach are proposed which are applicable to over-actuated nonlinear systems. Instead of solving the control allocation exactly, update laws for the desired control effector signals are defined such that they converge to the optimal solution. Stability and boundedness of the resulting closed-loop system can be shown by means of Lyapunov analysis. Three different update laws are defined, the integrated, modular and composite adaptive designs. The last can be seen as a combination between the first two and has the best convergence and numerical properties. Second-order actuator dynamics are taken into account in the control designs. The control design is evaluated using numerical simulations where several cases of locked control surface failures are considered during two different maneuvers. No sensor information about these failures is fed back to the control system. The tracking performance of the adaptive control design is excellent for the nominal case and all considered failure cases. The failures are recognized shortly after they are introduced into the system, and the new dynamics are rapidly identified.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:b33ea605-5d9f-45c8-b8f6-f6b714c1e9e9","http://resolver.tudelft.nl/uuid:b33ea605-5d9f-45c8-b8f6-f6b714c1e9e9","Registering pointclouds of polyhedral buildings to 2D maps","Khoshelham, K.; Gorte, B.G.","Remondino, F. (contributor); El-Hakim, S. (contributor); Gonzo, L. (contributor)","2009","This paper presents a method for automated pointcloud-to-map registration using a plane matching technique. The registration is based on estimating a transformation between a set of planes inferred from the map and their corresponding planes extracted from the pointcloud. A plane matching algorithm is developed to search for corresponding planes in the pointcloud and map coordinate systems, and estimate the transformation between the corresponding planes. The search for correspondences takes advantage of an initiate-and-extend strategy to avoid high computational cost of an extensive search. The search strategy is further strengthened by using a linear model for the estimation of the transformation. The plane matching algorithm is shown to perform robustly in the presence of outlier and missing planes, and achieve accuracies in the order of centimetres as the mean distance between the transformed pointcloud planes and the map planes","Terrestrial laser scanning; Automation; Building; Map; Referencing; PointCloud; Plane Matching","en","conference paper","International Society for Photogrammetry and Remote Sensing","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:78b4c204-0b59-4bf4-a5b6-1be4536d329c","http://resolver.tudelft.nl/uuid:78b4c204-0b59-4bf4-a5b6-1be4536d329c","Cooperative Control of Swarms of Unmanned Aerial Vehicles","De Vries, E.; Subbarao, K.","","2011","Potential function based swarm control is a technique using artificial potential functions to generate steering commands resulting in swarming behavior. This means that the vehicles in the swarm autonomously take care of flying in formation, resulting in steering the swarm, instead of all the individual vehicles being tasked separately. This form of cooperative control is very effective for large groups of unmanned aerial vehicles (UAVs). To test this technique, a simulation tool (in SIMULINK) has been developed using a swarm of quadrotors with nonlinear dynamics. Quadrotors are suitable testbeds due to their mechanical simplicity and can be described by reasonably simple dynamical equations of motion. The inner loop control laws for the quadrotor are based on a backstepping like technique with a nested multi-loop structure. After verification of the individual vehicle model, a multi-UAV controller was designed using potential functions to generate the swarming behavior. The results show that the potential function based method is effective in swarm aggregation. The swarm controller is able to cope with inflight changes of the number of agents if, due to communication limits, one or more agents drift in or out of range. The ability to avoid obstacles by adding obstacle avoidance terms to the steering commands is also shown. These terms are sensitive to the velocities of the swarm members and the gains. However, much better results are expected when a path shaping module is added. This will not only add the ability to fly along a path, but it will also solve the problem of saturated velocity commands due to large differences between the quadrotor position and the goal position.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9d58d1b6-453e-4f3b-85c7-65327a09aaf9","http://resolver.tudelft.nl/uuid:9d58d1b6-453e-4f3b-85c7-65327a09aaf9","Experimental and Numerical Results on Cavity Effects in Juncture Flow","Horsten, B.J.C.; Veldhuis, L.L.M.","","2008","","","en","conference paper","American Institute of Aeronautics and Astronautics, AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e03b503b-89be-43ca-af97-17ec20ed1f71","http://resolver.tudelft.nl/uuid:e03b503b-89be-43ca-af97-17ec20ed1f71","Towards a control-theoretic model of pilot manual control behaviour with a perspective flight-path display","Mulder, M.","","1995","","manual control; perspective flight-path displays; human operator modelling","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:04b3f063-17f7-46c0-b9c9-782aefc0bc25","http://resolver.tudelft.nl/uuid:04b3f063-17f7-46c0-b9c9-782aefc0bc25","A tool for aerodynamic analysis of flexible kites (poster)","Franca, B.; Schmehl, R.","","2015","Poster presented at International Airborne Wind Energy Conference (AWEC), 2015.","","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:26d279d8-9206-4689-ab2e-23f28dabe3e3","http://resolver.tudelft.nl/uuid:26d279d8-9206-4689-ab2e-23f28dabe3e3","Constraint-based decision support for multi-objective arrival traffic planning","Vormer, F.J.; Boer, E.R.; Van Paassen, M.M.; Mulder, M.; Davison, H.J.","","2003","","air traffic planning; naturalistic decision making; satisficing decision making; situation awareness; human-machine interaction","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:12f1b18f-7d16-4049-8eae-b707337e8e7e","http://resolver.tudelft.nl/uuid:12f1b18f-7d16-4049-8eae-b707337e8e7e","Towards Integrating Traffic and Terrain Constraints into a Vertical Situation Display","Rijneveld, P.; Borst, C.; Mulder, M.; Van Paassen, M.M.","","2010","Future airspace operations will allow flight crews to plan and fly their own preferred route and time of arrival without much intervention from air traffic control. This implies that pilots become more responsible for planning their own route while maintaining safe separation. This requires a strategic planning tool that support a high level of pilot Situation Awareness. Current aircraft are already equipped with terrain and traffic warning systems to, but these systems only provide short-term conflict resolutions. Recent studies have shown that a constraint-based approach to interface design could be used to support long- and medium-term decision-making and to provide a deeper understanding of the work domain. However, these studies were focused on either terrain or traffic. This paper aims to integrate both by showing the performance, traffic and terrain overlays on an experimental Vertical Situation Display. In a simulator evaluation, in which twelve professional airline pilots participated, this Vertical Situation Display was compared to a baseline Vertical Situation Display that only showed a terrain overlay and intruder aircraft relative to own ship. The experiment results revealed that the performance, traffic and terrain overlays improved pilots’ overall situation awareness and pilots rated their workload lower. Regarding decision-making, however, the results were not significantly better. Regarding safety, there were less traffic conflicts, but more ground proximity intrusions.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:5a2ae89d-961a-4251-bc03-c642a2d6d6e4","http://resolver.tudelft.nl/uuid:5a2ae89d-961a-4251-bc03-c642a2d6d6e4","Aspects of goal-oriented model-error estimation in convection-diffusion problems","Cnossen, J.M.; Bijl, H.; Gerritsma, M.I.; Koren, B.","","2006","For goal-oriented model adaptation a model-error estimator is required to drive the adaptation process. In recent years publications have appeared on the dual-weighted residual (DWR) method in the application of model-error estimation in output functionals. In this paper we study the application of the DWR method for convection-diffusion problems where hierarchical models are of different type. Omitting the diffusion operator often results in a singular perturbation problem considering the model residual in the limit of vanishing diffusion. This is caused by the change of mathematical type of the model equations and therefore the applied boundary conditions. In this work we show how a model error estimator is developed for steady and unsteady convection-diffusion problems. It is found that a weak formulation and weakly imposing boundary and initial conditions leads to a dual-weighted model-error estimator that also incorporates boundary residuals.","model error; hierarchical modelling; goal-oriented error estimation; dualweighted residual method; convection-diffusion problems","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6e3524a7-71c9-4fc8-a9b8-464fd5f21056","http://resolver.tudelft.nl/uuid:6e3524a7-71c9-4fc8-a9b8-464fd5f21056","Environmental impact evaluation using an agent based simulation framework","Schroijen, M.J.T.; Van Tooren, M.J.L.","","2010","Environmental issues play an increasingly important role in aviation, affecting the desirability of novel technologies directly. The desirability of a certain technology with respect to environmental issues is determined by the system of systems level impact instead of the often used system level impact. Changing this perspective introduces additional complexities in how the system level evaluation should be related to the desired system of systems (SoS) level evaluation. A framework is proposed, using agent based simulation, to evaluate the emergent behaviour of the intertwined stakeholders and the subsequent impact of the novel technology. The Maglev assisted aircraft launch system is considered as a test case to evaluate the complexities arising in the proposed approach. The three evaluated scenarios showed a large behavioural effect on the system of sys- tems level environmental impact. Even though data in the scenarios were assumed and behaviour simplified, the knowledge obtained by the agent based simulation improved the understanding of the mechanisms affecting the environmental impact. Finally, the modular approach allows for an extension of the framework to evaluate more realistic scenarios.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:3ce24d45-5d3d-4868-8419-5fa5625937d8","http://resolver.tudelft.nl/uuid:3ce24d45-5d3d-4868-8419-5fa5625937d8","Airfoil Analysis with Uncertain Geometry using the Probabilistic Collocation method","Loeven, G.J.A.; Bijl, H.","","2008","Due to manufacturing tolerances, the airfoil of a wing after production is never exactly the same as the designed airfoil. Also during operation the geometry may change due to aerodynamic loading, icing or wear of the construction. The geometry can, therefore, be treated as uncertain. Uncertainties in the geometry of an airfoil are expected to have a significant influence on quantities like lift and drag. Computational Fluid Dynamics is a tool to investigate the flow around an airfoil, which is characterized by large time consuming computations. Since uncertainty quantification increases the amount of computational work, efficiency is of great importance. To limit the number of uncertain parameters, the geometry is parameterized using a few parameters. The geometric uncertainties are then treated as parametric uncertainties, which are efficiently propagated using the Probabilistic Collocation method. Results are shown for uncertain NACA 4-digit series airfoils, where the maximum camber, maximum camber position and the thickness of the airfoil are assumed to be uncertain. It is shown that geometric uncertainties have significant influence on the drag polar. The uncertainties are propagated through the system separately to see the effect of the parameter on the solution and simultaneously to investigate combined effects.","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:f99b5b25-1ae6-45ef-8130-68fcbfd2971f","http://resolver.tudelft.nl/uuid:f99b5b25-1ae6-45ef-8130-68fcbfd2971f","Large-volume pressure from tomographic PTV in a surface mounted cylinder near-wake using HFSB tracers","Schneiders, J.F.G.; Caridi, G.; Sciacchitano, A.; Scarano, F.","","2015","","","en","conference paper","University of Poitiers","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:5feb9aa6-d1bc-482b-8570-7e892bdf3bc5","http://resolver.tudelft.nl/uuid:5feb9aa6-d1bc-482b-8570-7e892bdf3bc5","Optimization based image registration in the presence of moving objects","Karimi Nejadasl, F.; Gorte, B.G.H.; Hoogendoorn, S.P.; Snellen, M.","","2008","","registration; optimization; Differential Evolution; Nelder-Mead; 3D Euclidean","en","conference paper","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:0f3a9b98-2d8c-450c-abd3-7daa3bcf9c67","http://resolver.tudelft.nl/uuid:0f3a9b98-2d8c-450c-abd3-7daa3bcf9c67","Green Freighter Systems","Slingerland, R.; Zandstra, S.; Scholz, D.; Seeckt, K.","","2008","","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","","","","",""
"uuid:04e213ea-6102-4789-81c3-b2e2a2ebccf0","http://resolver.tudelft.nl/uuid:04e213ea-6102-4789-81c3-b2e2a2ebccf0","Simplified 3D city models from LiDAR","Lesparre, J.; Gorte, B.G.H.","","2012","Aerial laser scan data is widely used to produce 2½D digital elevation models automatically. However, creating full 3D city models from this data is a complex task. A simplified 3D model, like a 2½D model with vertical walls will be easier to produce automatically, especially when the model is not produced to look nice, but just to give realistic results in an analysis or a simulation. To be able to include vertical walls in a 2½D model we extend the TIN data structure in such way that the height of a vertex is stored implicitly in a way that allows multiple heights and efficient processing at the same time. To generate the city model we first apply data reduction in planar areas of an initial TIN. Next, we segment the TIN into planar segments for the ground, walls and roof planes. Finally, we intersect the segments to obtain a 2½D model with slightly slanted walls, which should be adjusted to become exactly vertical. The results for simulated point cloud data are near-perfect. Real aerial laser scan data are more challenging, but the method still gives promising results.","LiDAR; point cloud; TIN; data reduction; segmentation; reconstruction; 3D city model","en","conference paper","International Society for Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:6ad6375b-31b8-4b7b-91b3-f68ece3132f0","http://resolver.tudelft.nl/uuid:6ad6375b-31b8-4b7b-91b3-f68ece3132f0","The concept of fatigue fracture toughness in fatigue delamination growth behavior","Yao, L.; Alderliesten, R.C.; Benedictus, R.","","2015","This paper provides a study on mode I fatigue delamination growth in composite laminates using energy principles. Experimental data has been obtained from fatigue tests conducted on Double Cantilever Beam (DCB) specimens at various stress ratios. A concept of fatigue fracture toughness is proposed to interpret the stress ratio effect in crack growth. The fatigue fracture toughness is demonstrated to be significantly stress ratio dependent. An explanation for this phenomenon is given using SEM fractography. Fracture surface is observed to be rougher for high stress ratio in comparison with that for low stress ratio, causing the fatigue resistance increase. Therefore, the stress ratio effect in fatigue crack growth can be physically explained by a difference in resistance to crack growth.","energy principles; fatigue delamination; fracture toughness; composite laminates","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:9e84009f-423b-4716-a501-12f3c6218a1d","http://resolver.tudelft.nl/uuid:9e84009f-423b-4716-a501-12f3c6218a1d","Tackling the challenges in buying value-added marketing services","van der Valk, W.; Reunis, M.R.B.; Wynstra, F.","","2005","","buyer-seller interfaces; marketing services; marketing-purchasing interfaces","en","conference paper","IMP Group","","","","","","","","Aerospace Engineering","","","","",""
"uuid:76443da2-a949-474a-862b-a4f95ac59e3d","http://resolver.tudelft.nl/uuid:76443da2-a949-474a-862b-a4f95ac59e3d","Perspectices for annunciator systems","Van Paassen, M.M.R.; Wieringa, P.A.","","1997","","","en","conference paper","University of Kassel - GhK","","","","","","","","Aerospace Engineering","","","","",""
"uuid:fa6f33db-ebf6-4ec0-9b1d-b87abdba1e23","http://resolver.tudelft.nl/uuid:fa6f33db-ebf6-4ec0-9b1d-b87abdba1e23","Validating the Multidimensional Spline Based Global Aerodynamic Model for the Cessna Citation II","De Visser, C.C.; Mulder, J.A.","","2011","The validation of aerodynamic models created using flight test data is a time consuming and often costly process. In this paper a new method for the validation of global nonlinear aerodynamic models based on multivariate simplex splines is presented. This new method uses the unique properties of the multivariate simplex splines, a recent type of of multivariate spline, to speedup the process of aerodynamic model validation. Multivariate simplex splines are defined on non-rectangular domains and can be used to accurately fit scattered nonlinear datasets in any number of dimensions. The simplex splines consist of piecewise defined, ordinary multivariate polynomials with a predefined continuity between neighboring polynomial pieces. A recent method for nonlinear system identification based on multivariate simplex splines was used to create a global nonlinear aerodynamic model of the Cessna Citation II laboratory aircraft operated by the Delft University of Technology. In this paper, the multivariate spline based aerodynamic model for the pitching moment coefficient will be validated using both a model residual analysis as well as a statistical model quality analysis. It will be demonstrated that these new analysis methods, which are both unique to the multivariate simplex splines, provide a highly efficient and powerful new method for aerodynamic model validation.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:72716931-3cb0-47c4-a320-f867d772d935","http://resolver.tudelft.nl/uuid:72716931-3cb0-47c4-a320-f867d772d935","On the suitability of direct application of acoustic theory to time-resolved tomographic PIV tested by DNS for low Mach number jet flows","Moore, P.; Violato, D.; Bryon, K.; Scarano, F.","","2010","In this paper, we investigate the minimum temporal requirements, spatial domain and spatial resolution requirements in order to make acoustic predictions by means of acoustic analogies, for low speed jet flows, by means of numerical simulations. This work is done to demonstrate the feasibility of indirect acoustic extrapolation from recent experiments undertaken by us and to develop robust techniques. For this paper we consider Direct Numerical Simulation of incompressible jets flows of Reynolds number 2,500 and Reynolds number 5,000 jets. Comparison of flow statistics and visualizations confirms that the simulations are representative of the jets obtained in our experiments. Lighthill’s and Powell’s aerocaoustic analogies are applied and demonstrated to yield indirect acoustic predictions of these jets, especially at 90º to the flow axis, where the coordinate origin dependency of Powell’s acoustic analogy is minimal. Finally we investigate the robustness of these indirect acoustic predictions when the DNS simulation data is reduced in temporal and spatial extent and resolution to those currently achievable by our Tomographic PIV setup. The results indicate that our current measurement capabilities are suitable for obtaining acoustic spectra up to a Strouhal number of 1.0. Moreover, in order to improve the spectral cut-off, it is preferable to increase the spatial resolution of the measurements at the expense of domain size and temporal resolution.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:c452bdd8-e869-46ec-951f-20bf68b0281c","http://resolver.tudelft.nl/uuid:c452bdd8-e869-46ec-951f-20bf68b0281c","Phase Coherence Zones in Flight Simulation","Jonik, P.M.; Valente Pais, A.R.; Van Paassen, M.M.; Mulder, M.","","2011","In flight simulation detailed knowledge of human motion perception is crucial. Phase differences between inertial and visual motion introduced by motion filters might have negative effects on the fidelity of flight simulation. This study investigated human visual- vestibular phase-error detection. An experiment was conducted to measure the maximum amount of phase lead of the inertial motion with respect to the visual motion that remains undetected by the human. It contributes to the assessment of so-called coherence zones investigated in previous studies. Possible effects of the stimulus frequency, amplitude and the axis of rotation were examined. They were found to have no significant influence on phase-error detection. The average phase-error threshold was determined at 22 degrees. In accordance to previous studies the results showed that humans can be considered more like phase-error detectors rather than time delay detectors.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:84eb9c01-2c1d-4db0-86d4-7c254e7a2bb5","http://resolver.tudelft.nl/uuid:84eb9c01-2c1d-4db0-86d4-7c254e7a2bb5","Service oriented concurrent engineering with hybrid teams using a multi-agent task environment","Berends, J.P.T.J.; van Tooren, M.J.L.","","2008","","Service Oriented Engineering; Multidisciplinary Design Optimisation: Design and Engineering Engine; Knowledge Based Engineering; Multi-agent Task Environment; Engineering Frameworks","en","conference paper","Springer Verlag","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f34844c4-213d-4e63-81a1-ae631bdb8b63","http://resolver.tudelft.nl/uuid:f34844c4-213d-4e63-81a1-ae631bdb8b63","Towards integral boundary layer modelling of passive vortex generators (poster)","Baldacchino, D.; Simao Ferreira, C.J.; Van Bussel, G.J.W.","","2014","","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:41be517e-979b-406a-b5cc-c214ec7958df","http://resolver.tudelft.nl/uuid:41be517e-979b-406a-b5cc-c214ec7958df","Coarse level Newton-Krylov acceleration of sub-iterations in partitioned fluid-structure interaction","Van Zuijlen, A.H.; Bijl, H.","","2011","Computational fluid-structure interaction is commonly performed using a partitioned approach. For strongly coupled problems sub-iterations are required, increasing computational time as flow and structure have to be resolved multiple times every time step. Reductions in computing times can be achieved by e.g. improving the convergence of the sub-iteration technique and/or performing sub-iterations on a coarse level, but also by improving the iterative solver used in the flow solver. In this paper we investigate the combination of a multilevel acceleration technique for sub-iterations which employs a Newton-Krylov solver on the coarse level to obtain high convergence for the correction term and a multigrid solver which performs only a limited amount of iterations on the fine level to reduce memory and computing requirements. For switching between a coarse grid correction and fine grid solve, an automated coarse grid ACG(r) selection algorithm is proposed. The algorithm is applied to an academic, two dimensional test case with incompressible flow. Compared to sub-iterating with a (memory intensive) JFNK algorithm on the fine mesh, the hybrid algorithm already requires 10% less computing time. When compared to sub-iterating with multigrid, the performance increase for the hybrid scheme is a factor 3.","high order time integration; fluid-structure interaction; partitioned integration","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:520bf4ee-388c-4848-a8ec-70eabcfafc50","http://resolver.tudelft.nl/uuid:520bf4ee-388c-4848-a8ec-70eabcfafc50","Wavelet de-noising of terrestrial laser scanner data for the characterization of rock surface roughness","Khoshelham, K.; Altundag, D.","","2010","The application of terrestrial laser scanning to the study of rock surface roughness faces a major challenge: the inherent range imprecision makes the extraction of roughness parameters difficult. In practice, when roughness is in millimeter scale it is often lost in the range measurement noise. The parameters extracted from the data, therefore, reflect noise rather than the actual roughness of the surface. In this paper we investigate the role of wavelet de-noising methods in the reliable characterization of roughness using laser range data. The application of several wavelet decomposition and thresholding methods are demonstrated, and the performances of these methods in estimating roughness parameters are compared. As the main measure of roughness fractal dimension is derived from 1D profiles in different directions using the roughness length method. It is shown that wavelet de-noising in general leads to an improved estimation of the fractal dimension for the roughness profiles. The choice of the decomposition method is shown to have a minor effect on the de-noising results; however, the application of hard or soft thresholding mode does have a considerable influence on the estimated roughness measures. The presented results suggest that hard thresholding yields more accurate de-noised profiles for which the estimated roughness measures are more reliable.","laser scanning; roughness length; measurement noise; wavelet decomposition; thresholding; fractal dimension","en","conference paper","International Society of Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:9c8890f9-f52f-49b4-b63a-a1da87343871","http://resolver.tudelft.nl/uuid:9c8890f9-f52f-49b4-b63a-a1da87343871","3D wake dynamics of the VAWT: Experimental and numerical investigation","Ferreira, C.; Hofemann, C.; Dixon, K.; Van Kuik, G.A.M.; Van Bussel, G.J.W.","","2010","The Vertical Axis Wind Turbine, in its 2D form, is characterized by a complex unsteady aerodynamic flow, including dynamic stall and blade vortex interaction. Adding to this complexity, the 3D flow causes spanwise effects and the presence of trailing vorticity and tip vortices. The objective of the current paper is to bring insight into the 3D development of the near wake of a H-VAWT, understanding: The spanwise blade load distribution in the upwind and the downwind blade passages. The trajectory of tip vortices, including the inboard movement and the radial expansion of the shed and the trailing vorticity. The impact of the 3D flow phenomena on the efficiency of the VAWT. The blade vortex interaction of the upwind tip vortex with the downwind blade passage. The induction due to trailing vorticity. The investigation is composed of experimental wind tunnel research with Stereo-PIV and modeling of the rotor and wake with a 3D unsteady panel method. A two bladed H-Darrieus VAWT model is tested in the low speed/low turbulence wind tunnel at Delft University of Technology. Stereo-PIV measurements are used to visualize the flow in the near wake focusing on the flow field around four tip geometries. The measurement planes cover several sections of the rotor volume, allowing for the reconstruction of the evolution of the tip vortex. The formation, the convection and the dissipation for each tip vortex are quantified. The experimental PIV data is used to validate the 3D, unsteady, multi-body, free-wake panel method. The combination of the results of the panel model validated by experiments, in particular the Stereo PIV results, allows to understand the impact of the near wake development on the upwind blade passage, as well as the energy conversion process during the downwind blade passage.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:a3cbea95-5576-4650-ade5-1a2589981a6c","http://resolver.tudelft.nl/uuid:a3cbea95-5576-4650-ade5-1a2589981a6c","Is blade element momentum theory (BEM) enough for smart rotor design","Yu, W.; Simao Ferreira, C.J.; van Kuik, G.A.M.","","2014","Smart rotor emerges as an innovation technique to reduce the impact of dynamic loading on wind turbines. Local movements of distributed aerodynamic devices will enhance the non-uniformity and dynamic effects of loading, which will challenge the applicability of the blade element momentum theory (BEM) for smart rotor control design due to its fundamental assumptions, quasi-steady state and independent annuli. From a recent report of Sandia Lab of field tests of wind turbine with trailing edge flaps, an unsteady aerodynamic model for the response to turbulent wind and AALC device actuation is needed and a dynamic wake model is necesary[1]. However, most of previous aeroseverelastic studies of smart rotor are based on BEM or BEM-based engineering dynamic inflow models, none of them verify the applicability of BEM for smart rotor study. In this paper, a free wake model which combined a vortex ring model with a semi-infinite cylindrical vortex tube is developed, and applied to an actuator disc with non-uniform and dynamic loading. After tested in a steady, uniform load case, the model is applied to three main load cases: a non-uniform steady load, a uniform dynamic load and a non-uniform dynamic load. Results from this model are compared with MT, and with two widely used engineering dynamic inflow models.","","","conference paper","EAWE European Academy of Wind Energy","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:f0483aa3-2a1b-4700-b78e-12dbab6c6a2b","http://resolver.tudelft.nl/uuid:f0483aa3-2a1b-4700-b78e-12dbab6c6a2b","Buckling optimization of steering stiffeners for grid-stiffened composite structures","Wang, D.; Abdalla, M.M.","","2015","Grid-stiffened composite structures, where the skin is stiffened by a lattice of stiffeners, not only allow for significant reduction in structural weight but are also competitive in terms of structural stability and damage tolerance compared with sandwich composite structures. As the development of Automated Fiber Placement (AFP) technology matures, integrated construction of skin and stiffeners is easily manufacturable. Optimization of grid-stiffened structures is needed to fully take advantage of the expanded design possibilities. In this paper, a steering/curved stiffener layout is optimized for grid-stiffened composite structures in order to enhance the structural buckling resistance. A homogenization method is used to calculate the equivalent material properties. Global and local buckling loads are determined by a global/local coupled strategy. A linear variation of stiffener angles is assumed resulting in the formation of a locally rhombic lattice pattern by the stiffeners. Moreover, manufacturing constraints are considered in the optimization by setting a lower bound on the stiffener spacing. Since the calculation is implemented on an equivalent model with a fixed mesh, it is possible to use a gradient-based optimization algorithm. A comparison between the performance of grid-stiffened composite structures with curved stiffeners, with straight stiffeners, and with variable-stiffness skins with curved fibers, reveals the potential of curved stiffener configurations in improving structural efficiency.","curved stiffeners; optimization; grid-stiffened composite structures; global and local buckling","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:5b073ba9-57d5-41f3-a337-5a737fb8acaa","http://resolver.tudelft.nl/uuid:5b073ba9-57d5-41f3-a337-5a737fb8acaa","River bed classification using multi-beam echo-sounder backscatter data","Kinneging, N.; Snellen, M.; Eleftherakis, D.; Simons, D.G.; Mosselman, E.; Siben, A.","","2012","The Netherlands form the delta for some of the major river systems of Europe, comprising the Rhine, the Meuse, the Scheldt and the Eems. These rivers are valuable parts of national and international ecological networks and are of high economic importance. A minimum depth should be guaranteed to keep the rivers navigable. This depth depends not only on water discharge but also on river bed topography that changes dynamically in response to discharge fluctuations. Rijkswaterstaat is the Dutch governmental organization that is responsible to maintain the main river systems for both shipping, flood conveyance and ecological purposes. To keep the rivers navigable daily dredging activities are carried out. Furthermore the discharge capacity of the rivers is enlarged and the ecological quality is improved by widening the river and making secondary channels. The river topography and its dynamics are affected by spatial variations in bed sediment composition, thus making knowledge of the spatial sediment distribution highly important. It proved to be sufficient to detect a number of classes to produce classification maps of the bottom. An attractive system to be used for obtaining information on both the river bed bathymetry and sediment composition is the multi-beam echo-sounder (MBES). This sonar emits short pulses of sound towards the river bed to determine the depth and the backscatter strength for a large number of closely-spaced beams. The MBES provides high spatial coverage of an area at moderate costs and within short time. The backscatter strengths are known to be indicative for the sediment types, and consequently have potential with regard to sediment classification. Consequently, the MBES system appears as a good alternative to the conventional, expensive and time-consuming, approach of mapping the river bed composition by taking a large number of physical sediment samples. In the present paper, the results of a novel and fairly simple sediment classification method are presented. The method that developed in the Acoustic Remote Sensing Group of Delft University of technology is briefly described in the following section.","","en","conference paper","Deltares & Hydrographic Society Benelux","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:5af0f828-b099-4aa5-8e59-fff28b6e59f4","http://resolver.tudelft.nl/uuid:5af0f828-b099-4aa5-8e59-fff28b6e59f4","Design status of the Delfi-Next nanosatellite project","Bouwmeester, J.; Brouwer, G.F.; Gill, E.K.A.; Monna, G.L.E.; Rotteveel, J.","","2010","Delfi-Next is the second project within the Delfi nanosatellite development program of Delft University of Technology. It will provide students hands-on experience, facilitate technology demonstration for innovative miniaturized space technology from the Dutch space sector and allow advancements in satellite bus performance compared to its predecessor Delfi-C3. This paper will describe the mission and provides insight in the design status and trade-offs of each bus subsystem at September 2010. A micropropulsion system from TNO, an in-orbit configurable radio from ISIS BV and amorphous silicon solar cells will be demonstrated onboard Delfi-Next. The electrical power subsystem consists of deployable solar panels, a central power management unit, a battery system and local power regulation units on each printed circuit board. The central power management unit uses redundant maximum power point trackers for each solar panel and distributes the acquired power to a standard system bus on a fixed single supply voltage of 12V, the battery system and a shunt for excessive power. The communication subsystem consists of two redundant radios transmitting a continuous 1.2 9.6 kbps signal on a 145 MHz carrier frequency, a high data rate S-band transmitter, a receiver and a set of deployable antennae in a turnstile configuration. The downlink is received by a global distributed ground station network consisting of several universities and radio amateurs. Onboard data handling is performed by a hot redundant onboard computer, which manages and acquires measurement data from local subsystem microcontrollers by means of an I2C data bus. Because the standard implementation of I2C lacks failure tolerance it is supplemented with bus buffers on each local system which will isolate malfunctioning nodes from the main bus when necessary. A custom designed spacecraft structure optimized for accessibility will provide the basis for all physical subsystems which are made compliant to a standardized form factor. The structure complies with the outer dimensions of a triple-unit CubeSat. Passive thermal control based on heat sinks and optical properties of surface materials will keep components and subsystems within the required thermal range. Attitude determination and control will be performed by a suite of sensors, actuators and processing algorithms to demonstrate active attitude control functionality as a baseline for future Delfi missions. Future Delfi missions to demonstrate formation flying capabilities are foreseen, potentially within the QB-50 network for thermospheric research or demonstration missions for the OLFAR moon-orbiting radio telescope.","","en","conference paper","International Astronautical Federation","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:28d05af6-5806-4319-9bcc-a65e7e5b4e83","http://resolver.tudelft.nl/uuid:28d05af6-5806-4319-9bcc-a65e7e5b4e83","Visual-inertial coherence zone in the perception of heading","De Winkel, K.N.; Correia Gracio, B.J.; Groen, E.L.; Werkhoven, P.","","2010","Knowledge of human motion perception can be applied in the optimization of motion cueing algorithms. In the past it has been shown that some discrepancies between the amplitude or phase of a visual and inertial cue go unnoticed. These acceptable discrepancies are referred to as coherence zones. In the present experiment we investigate whether a coherence zone applies to the direction of visual and inertial motion cues. More specifically, we investigated how much heading of an inertial stimulus may deviate from a visual stimulus suggesting ‘straight ahead’ motion, before the ‘straight ahead’ percept falls apart. Subjects were presented with congruent visual-inertial linear horizontal motion stimuli with varying heading and incongruent visual-inertial linear horizontal motion stimuli, in which a visual cue suggesting straight ahead motion was coupled with an inertial heading cue with varying heading. Subjects judged I) whether or not they moved straight ahead, and II) whether or not the visual and inertial stimulus were congruent. We fitted psychometric curves to the combined judgments and calculated detection thresholds for a violation of either criterion. The results show that the 50% detection thresholds are larger in the incongruent than in the congruent condition. We interpret the threshold for the incongruent condition as the size of the coherence zone. In conclusion: we provide evidence of a coherence zone for heading, as wella as a measure of the size of the heading coherence zone.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:42ff2f29-f270-4c4b-9f95-8bbbdf7469ba","http://resolver.tudelft.nl/uuid:42ff2f29-f270-4c4b-9f95-8bbbdf7469ba","Evaluation of DEM-assisted SAR coregistration","Nitti, D.O.; Hanssen, R.F.; recife, A.; Bovenga, F.; Milillo, G.; Nutricato, R.","","2008","Image alignment is without doubt the most crucial step in SAR Interferometry. Interferogram formation requires images to be coregistered with an accuracy of better than 1/8 pixel to avoid significant loss of phase coherence. Conventional interferometric precise coregistration methods for full-resolution SAR data (Single-Look Complex imagery, or SLC) are based on the cross-correlation of the SLC data, either in the original complex form or as squared amplitudes. Offset vectors in slant range and azimuth directions are computed on a large number of windows, according to the estimated correlation peaks. Then, a two-dimensional polynomial of a certain degree is usually chosen as warp function and the polynomial parameters are estimated through LMS fit from the shifts measured on the image windows. In case of rough topography and long baselines, the polynomial approximation for the warp function becomes inaccurate, leading to local misregistrations. Moreover, these effects increase with the spatial resolution and then with the sampling frequency of the sensor, as first results on TerraSAR-X interferometry confirm. An improved, DEM-assisted image coregistration procedure can be adopted for providing higher-order prediction of the offset vectors. Instead of estimating the shifts on a limited number of patches and using a polynomial approximation for the transformation, this approach computes pixel by pixel the correspondence between master and slave by using the orbital data and a reference DEM. This study assesses the performance of this approach with respect to the standard procedure. In particular, both analytical relationships and simulations will evaluate the impact of the finite vertical accuracy of the DEM on the final coregistration precision for different radar postings and relative positions of satellites. The two approaches are compared by processing real data at different carrier frequencies and using the interferometric coherence as quality figure.","Synthetic Aperture Radar (SAR); interferometry; coregistration; Digital Evaluation Model (DEM)","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Mathematical Geodesy & Positioning","","","",""
"uuid:70884d11-faa7-4bf2-bc73-d052801022a0","http://resolver.tudelft.nl/uuid:70884d11-faa7-4bf2-bc73-d052801022a0","A Second-Order Improved Front Tracking Method for the Numerical Treatment of the Hyperbolic Euler Equations","Witteveen, J.A.S.","","2008","","","en","conference paper","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:dff7d6b3-b00a-4b22-8dac-eaf1d963722e","http://resolver.tudelft.nl/uuid:dff7d6b3-b00a-4b22-8dac-eaf1d963722e","An overview of NACA 6-digit airfoil series characteristics with reference to airfoils for large wind turbine blades","Timmer, W.A.","","2009","This paper investigates the NACA 63 and 64 6-digit series of airfoils tested in the NACA LTPT in view to verify the RFOIL calculated airfoil characteristics for high Reynolds numbers. Some anomalies in the zero-lift angles of 15% and 18% thick airfoils from these series are identified, both in the airfoil clean case and in case of wrap-around roughness. It is found that RFOIL predicts the maximum lift coefficient at a Reynolds number of 3 million well, but consistently under predicts the Cl,max for Reynolds numbers of 6 and 9 million. It is, however, based on other comparisons at high Reynolds numbers unclear if this is due to an inability of the prediction code or to a deviation in the test results. The drag coefficient is under predicted with about 9% for a wide range of airfoils and Reynolds numbers. Due to wrap-around roughness the maximum lift coefficient decreases with 18% to 20%.","","en","conference paper","American Institute of Aeronautics and Astronautics, AIAA","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:229fddd2-cd23-4547-9383-b95da4e5d7b1","http://resolver.tudelft.nl/uuid:229fddd2-cd23-4547-9383-b95da4e5d7b1","Explicit inverse distance weighting mesh motion for coupled problems","Witteveen, J.A.S.; Bijl, H.","","2009","An explicit mesh motion algorithm based on inverse distance weighting interpolation is presented. The explicit formulation leads to a fast mesh motion algorithm and an easy implementation. In addition, the proposed point-by-point method is robust and flexible in case of large deformations, hanging nodes, and parallelization. Mesh quality results and CPU time comparisons are presented for triangular and hexahedral unstructured meshes in an airfoil flutter fluid-structure interaction problem.","mesh motion; inverse distance weighting; explicit interpolation; point-by-point; fluid-structure interaction","en","conference paper","International Center for Numerical Methods in Engineering (CIMNE)","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:0ebae0e6-7814-4cd8-8179-9051431d4b38","http://resolver.tudelft.nl/uuid:0ebae0e6-7814-4cd8-8179-9051431d4b38","The environment provides the reference frame for self-motion perception","Van Der Steen, H.F.A.M.; Kamphuis, H.H.","","1995","","perception; visual; vestibular; visual-vestibular interaction; psychophysics; self-motion; perception models; optimal estimators","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7989ec76-c86d-4516-a0cc-df6f4affac82","http://resolver.tudelft.nl/uuid:7989ec76-c86d-4516-a0cc-df6f4affac82","Passivity Analysis for Non-Linear, Non-Stationary Entry Capsules: Rotational Motion","Mooij, E.","","2011","To analyze the passivity of non-linear, time-varying systems we study an entry capsule that enters the atmosphere in a lift-down configuration (i.e., a bank angle larger than 90º) to avoid skipping flight, and which is controlled by a Reaction Control System only. Deriving the passivity conditions for rotational motion, and evaluating these conditions along the trajectory shows that the (non-linear) entry capsule is Almost Strictly Passive, and the sufficient conditions to apply Simple Adaptive Control are met. Further, the preliminary design of an attitude-control system using the theory of Simple Adaptive Control is discussed and analyzed. The two designs for both a low and a high dynamic pressure operating condition show an excellent performance. Each design uses its own controller parameters (i.e., weighting matrices, zero integral gain and integral-gain filter parameter), which necessitates the use of an interpolation scheme once a trajectory with changing operating conditions is flown. The nominal mission (entry at 220 km altitude with a velocity of 11 km/s, and final conditions at Mach = 1) can be own without any difficulty. The angle-of-attack command is provided by a trim law, and although some deviations are observed when the capsule becomes less aerodynamically stable, this deviation does not diverge in spite of the pitch-thruster saturation. Responses due to errors in the initial attitude and angular rates show smooth curves in both attitude motion and thruster controls. A Monte-Carlo analysis that includes errors in the initial attitude, angular rate and inertia properties shows similar results, and it can be concluded that the performance of the controller given the current dispersions is satisfying.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:a1fb9a99-9727-4e54-b2fe-da46c0c73a3f","http://resolver.tudelft.nl/uuid:a1fb9a99-9727-4e54-b2fe-da46c0c73a3f","Post-buckled precompressed (PBP) elements: A new class of flight control actuators enhancing high-speed autonomous VTOL MAVs","Barrett, R.; McMurtry, R.; Vos, R.; Tiso, P.; De Breuker, R.","","2005","This paper describes a new class of flight control actuators using Post-Buckled Precompressed (PBP) piezoelectric elements. These actuators are designed to produce significantly higher deflection and force levels than conventional piezoelectric actuator elements. Classical laminate plate theory (CLPT) models are shown to work very well in capturing the behavior of the free, unloaded elements. A new high transverse deflection model which employs nonlinear structural relations is shown to successfully predict the performance of the PBP actuators as they are exposed to higher and higher levels of axial force, which induces post buckling deflections. A proof-of-concept empennage assembly and actuator were fabricated using the principles of PBP actuation. A single grid-fin flight control effector was driven by a 3.5” (88.9mm) long piezoceramic bimorph PBP actuator. By using the PBP configuration, deflections were controllably magnified 4.5 times with excellent correlation between theory and experiment. Quasi-static bench testing showed deflection levels in excess of ±6° at rates exceeding 15 Hz. The new solid state PBP actuator was shown to reduce the part count with respect to conventional servoactuators by an order of magnitude. Power consumption dropped from 24W to 100mW, weight was cut from 108g to 14g, slop went from 1.6° to 0.02° and current draw went from 5A to 1.4mA. The result was that the XQ-138 subscale UAV family experienced nearly a 4% reduction in operating empty weight via the switch from conventional to PBP actuators while in every other measure, gross performance was significantly enhanced.","piezoelectric; flight control; grid fin; post-buckled precompressed; MAV; UAV","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","System Engineering & Aircraft Design","","","",""
"uuid:9dff055c-eb6d-4005-a052-fce8aaeea792","http://resolver.tudelft.nl/uuid:9dff055c-eb6d-4005-a052-fce8aaeea792","Numerical Methods for the Optimization of Nonlinear Residual-Based Sungrid-Scale Models Using the Variational Germano Identity","Maher, G.D.; Hulshoff, S.J.","","2014","The Variational Germano Identity [1, 2] is used to optimize the coefficients of residual-based subgrid-scale models that arise from the application of a Variational Multiscale Method [3, 4]. It is demonstrated that numerical iterative methods can be used to solve the Germano relations to obtain values for the parameters of subgrid-scale models that are nonlinear in their coefficients. Specifically, the Newton-Raphson method is employed. A least-squares minimization formulation of the Germano Identity is developed to resolve issues that occur when the residual is positive and negative over different regions of the domain. In this case a Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm is used to solve the minimization problem. The developed method is applied to the one-dimensional unsteady forced Burgers’ equation and the two-dimensional steady Stokes’ equations. It is shown that the Newton-Raphson method and BFGS algorithm generally solve, or minimize the residual of, the Germano relations in a relatively small number of iterations. The optimized subgridscale models are shown to outperform standard SGS models with respect to a L2 error. Additionally, the nonlinear SGS models tend to achieve lower L2 errors than the linear models.","subgrid-scale model; variational multiscale method; variational Germano identity; optimization; turbulence","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:fbc64a39-931e-4b40-8803-486466f20703","http://resolver.tudelft.nl/uuid:fbc64a39-931e-4b40-8803-486466f20703","The potential of inverting geo-technical and geo-acoustic sediment parameters from single-beam echo sounder returns","Simons, D.G.; Snellen, M.; Siemes, K.","","2009","Seafloor characterization is important in many fields including hydrography, marine geology, coastal engineering and habitat mapping. The advantage of non-invasive acoustic methods for sediment characterization over conventional bottom grabbing is the nearly continuous versus sparse sensing and the enormous reduction in survey time and costs. Among the various acoustic systems for seafloor characterization, the single-beam echo sounder is of particular interest due to its simplicity and versatility. Seafloor characterization algorithms can be roughly divided into two categories: model-based and empirical, where the latter simply relies on the observation that certain echo features, such as amplitude, duration and skewness of the echo, are correlated with sediment type. Here we apply the model-based approach where we compare the measured echo signal with theoretically modeled echo envelopes in the time domain. For modeling the received echo sounder signals use is made of a physical backscatter model that fully accounts for watersediment interface roughness and sediment volume scattering. We use differential evolution, a fast variant of a genetic algorithm, as the global optimization method to invert the model input parameters mean grain size, spectral strength of the interface roughness and volume scattering cross section. In the model grain size determines geo-acoustic parameters like sediment sound speed, density and attenuation. The analysis is applied to simulated data.","single-beam echosounder; seafloor classification; optimization","en","conference paper","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:3b7097fe-fed6-4040-af4a-8af0b26f9a0d","http://resolver.tudelft.nl/uuid:3b7097fe-fed6-4040-af4a-8af0b26f9a0d","Fluid dynamic design and analysis of a highly loaded Centrifugal rotor for mini orc power systems","Vitale, S.; Pini, M.; Ghidoni, A.; Colonna di Paliano, P.","","2015","Organic Rankine Cycle (ORC) power systems are a well-established technology for the conversion of thermal energy sources in the small-to-medium power range. In the last few years, efforts have been devoted to the development of mini ORC (mORC) power systems (5- 30 kWe) for waste heat recovery from truck engines, or distributed conversion of concentrated solar radiation. In these high-temperature applications the expander is arguably the most critical component. Due to the high expansion ratio, turbo-expanders are typically preferred. Recently, a multi-stage radial-outflow turbine (ROT) configuration for ORC power systems has been studied. However, even if the authors preliminarily demonstrated that ROT may allow for compact and efficient expanders [1], some research questions are still open. Notably, the key point is the fluid dynamic design of the first stages, which are subject to severe flow conditions (very high flow deflection, low aspect ratio of the blades and with high tip clearance losses). This work thus proposes a novel design methodology for centrifugal cascades, specifically targeted to the first rotor of the mORC centrifugal turbine described in Ref. [1]. Blades are initially designed using a novel in-house Turbomachinery Blade Modeler (BM), then performance is verified by means of 3D CFD simulation on unstructured grids using the solver SU2, recently extended also in-house to treat non ideal compressible fluid flows [2]. Results show that traditional blade design rules for axial cascades are not directly extendable to centrifugal profiles and new design guidelines are needed. Moreover, the 3D performance of the cascade has also been investigated by taking into account tip clearance and secondary loss mechanisms. Finally, an accurate comparison with the mean-line code predictions is provided. As expected, the outcome of the study reveals moderate discrepancy between the CFD results and the mean-line code. This suggests that in case of non-conventional machines a more tight integration of design tools of increasing fidelity may be convenient.","","en","conference paper","ASME","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:597efbd5-c99c-45df-a92b-b1a455edc3b8","http://resolver.tudelft.nl/uuid:597efbd5-c99c-45df-a92b-b1a455edc3b8","Global Launcher Trajectory Optimization for Lunar Base Settlement","Pagano, A.; Mooij, E.","","2010","The problem of a mission to the Moon to set a permanent outpost can be tackled by dividing the journey into three phases: the Earth ascent, the Earth-Moon transfer and the lunar landing. In this paper we present an optimization analysis of Earth ascent trajectories of existing launch vehicles injected into a Low Earth parking orbit. The trajectories are optimized in the neighborhood of a reference guidance profile. The optimization problem is tackled by using a global method, and a single and multiobjective Particle Swarm Optimization algorithm serve the purpose. The final LEO payload mass is the objective function of the single-objective runs. Path constraints and final orbital elements are used as constraints in the process. However, in the multi-objective optimizations, these constraints are used as objectives together with the payload mass. The launchers' mechanical and thermal constraints, and the launch-sites azimuth constraint are taken into account. It is found that the highest payload masses are achieved by Ariane-5 ESC-A, Atlas V 552 and Proton M, with 25, 24 and 23 tons respectively. Such values, together with the use of all the three launchers and a tight schedule, would permit to build a base in 4.5 years. However, a manned launch vehicle is needed in order to guarantee the assembly and sup- port during the building phase. Also, the dedicated development of a heavy-lift launcher will greatly benefit the moon-base construction.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:e529270a-8fd1-4f02-bf4a-bf8ee0aca306","http://resolver.tudelft.nl/uuid:e529270a-8fd1-4f02-bf4a-bf8ee0aca306","Global Local Structural Optimization of Transportation Aircraft Wings","Ciampa, P.D.; Nagel, B.; Van Tooren, M.J.L.","","2010","The study presents a multilevel optimization methodology for the preliminary structural design of transportation aircraft wings. A global level is defined by taking into account the primary wing structural components (i.e., ribs, spars and skin) which are explicitly modeled by shell layered finite elements. Wing substructures such as stringers are implicitly represented by an equivalent formulation of the structural properties. The global level is analyzed and optimized for minimum mass under element stress constraints. Selected wing skin panels are extracted from the global wing and further remodeled with detailed stringers. Boundary conditions are transferred from the finite element (FE) global level solution to the FE detailed stiffened panel models. A finite element analysis is performed on the selected local level panels, which are mass optimized under additional stability constraints, providing a new optimal skin-stringer layout. The global model is then updated with the local level optimum results, and a number of iterative global-local optimization loops are executed. In the current study the DLR in-house tools are used for the structural modeling and sizing of the wing global level, and a new stiffened panel generator is introduced for the local level modeling. A local optimization module which includes instability failure criteria is implemented to redesign the stiffened panels for minimum mass. The global and the local levels communicate through a framework developed to assist an automated and exible multilevel optimization, and to minimize the time consuming activities required to generate detailed finite element models. The methodology is tested and demonstrated using a transportation DLR aircraft wing geometry as global level, and a variable number of upper skin blade stiffened panels remodeled in detail as local level.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:caa8ccd4-a626-49d8-8c0c-30fb4b0e74c3","http://resolver.tudelft.nl/uuid:caa8ccd4-a626-49d8-8c0c-30fb4b0e74c3","Review of design concepts, methods and considerations of offshore wind turbines","Ashuri, T.; Zaayer, M.B.","","2007","","","en","conference paper","European Wind Energy Association EWEA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:33950a07-dbaf-492b-bfec-8833984afd2f","http://resolver.tudelft.nl/uuid:33950a07-dbaf-492b-bfec-8833984afd2f","Comparison and validation of BEM and free wake unsteady panel model with the Mexico rotor experiment","Micallef, D.; Kloosterman, M.; Simao Ferreira, C.J.; Sant, A.; Van Bussel, G.J.W.","","2009","","MEXICO experiment; BEM; Free Wake Code","en","conference paper","European Mechanics Society","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:26d5c229-c770-4080-82af-b12ae97a2a0b","http://resolver.tudelft.nl/uuid:26d5c229-c770-4080-82af-b12ae97a2a0b","Multidisciplinary design and optimization of a plastic injection mold using an integrated design and engineering environment","Van Dijk, R.E.C.; dIppolito, R.; Tosi, G.; La Rocca, G.","","2011","In order to remain competitive with respect to low-cost overseas markets, domestic moldmakers will have to increase the productivity of their engineers and maintain high quality standard, while dealing with the problem of an aging workforce. To increase the competitiveness of the European automotive industry, the concept of and Integrated Design and Engineering Environment (IDEE) has been developed within the 6th framework European project Pegasus - Integrated engineering processing & materials technologies for the European sector. The IDEE consists of a distributed set of software applications able to accelerate the design process of plastic injection molds by means of process automation and multidisciplinary optimization techniques. The IDEE combines into a single user-friendly platform different technologies ranging from Knowledge Management (KM) and Knowledge-Based Engineering (KBE) to Process Integration and Automation (PI&A). Central to the IDEE framework is a KBE application, which consists of a fully parametric rule-based mold product model. On the basis of the geometry of the plastic part to be molded and other (user) inputs, the KBE application can automatically produce different mold configurations and variants. In this way, product knowledge is leveraged to automate the repetitive and therefore time-consuming CAD modelling activities typically encountered in industry. Next to the mold geometry, the KBE application is able to generate different reports that serve as input to in-house developed or commercially-of-the-shelf CAE applications, like Autodesk® Moldflow® Synergy. The resulting software framework enables the simulation and analysis of the injection molding process, from which important performance characteristics can be retrieved. Other disciplinary applications are used to assess the cost and the environmental impact of the molding process and tooling. All the IDEE software applications are provided as web services on remote servers according to the Software as a Service (SaaS) paradigm. Noesis’s Optimus software has been used to link them into a seamless framework, control their execution and support all data exchange in an automated fashion over the internet. The scope of this paper is to describe the architecture and main functionalities of the IDEE and provide the results of studies performed on representative plastic parts for the automotive industry. It is demonstrated how the IDEE can enable multidisciplinary optimization of the injection molding process and find solutions that best balance manufacturing performance and product quality. By means of the IDEE many concepts and customized variants can be quickly generated and evaluated in terms of hours or days instead of weeks or months, thereby supporting a more efficient development of innovative and complex parts. The reliability of the evaluation is enhanced by the early use of computer-based simulations in the design process, and the success rate of the overall component increased because of the more disciplines included in the evaluation (tooling design, material processing, cost, environmental impact). The IDEE can help the designer to virtually prototype and analyze the product and, eventually, support the “first-time-right” design principle.","multidisciplinary design and optimization; knowledge-based engineering; knowledge management; plastic injection mold design","en","conference paper","NAFEMS ltd","","","","","","","","Aerospace Engineering","Aerospace Design, Integration & Operations","","","",""
"uuid:4eb4b8d1-88c2-4f2c-9d49-ce0fdc5208dd","http://resolver.tudelft.nl/uuid:4eb4b8d1-88c2-4f2c-9d49-ce0fdc5208dd","Pilot-in-the-loop studies into manual control strategies with perspective flightpath displays","Theunissen, E.; Mulder, M.","","1995","","perspective flightpath displays; aircraft guidance; manual control","en","conference paper","Delft University of Technology","","","","","","","","Electrical Engineering, Aerospace Engineering","","","","",""
"uuid:3f29caf2-5769-4797-bd5f-1d30ee9db92b","http://resolver.tudelft.nl/uuid:3f29caf2-5769-4797-bd5f-1d30ee9db92b","A seven-factor procedural analysis of safety culture Known measurement - a case study at KLM E&M","Ghobbar, A.A.; Boutahri, F.; Curran, R.","","2009","","safety culture; human factors; maintenance error; aircraft maintenance","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","Aerospace Management and Operations Department","","","",""
"uuid:93750bab-d6d5-4398-a954-5c3692de421a","http://resolver.tudelft.nl/uuid:93750bab-d6d5-4398-a954-5c3692de421a","Status of the fast mission: Micro-satellite formation flying for technology, science and education","Guo, J.; Maessen, D.C.; Gill, E.K.A.; Moon, S.G.; Zheng, G.","","2009","FAST (Formation for Atmospheric Science and Technology demonstration) is a cooperative Dutch Chinese formation flying mission led by Delft University of Technology (TU Delft) in the Netherlands and Tsinghua University in China. It is expected to be the first international micro-satellite formation flying mission to achieve objectives in three distinct fields: technology demonstration, earth science and space education. In this paper the latest status of the FAST mission is presented. The mission scenario consisting of different formation flying stages is described, and the system design of both the space and the ground segments is introduced, with emphasis on Dutch contributions. Some key technical issues related to autonomous formation flying are also addressed.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:1c2897fd-ad41-414a-8344-171491f63d3b","http://resolver.tudelft.nl/uuid:1c2897fd-ad41-414a-8344-171491f63d3b","Relative state estimation and observability for formation flying satellites in the presence of sensor noise","Maessen, D.C.; Gill, E.K.A.","","2010","This paper presents an investigation into the relative state estimation and observability for two formation flying satellites using two different relative navigation sensor sets. The first set consists out of a transmitter antenna on one satellite and a single receiver antenna on the other satellite to measure the inter-satellite range using a radiofrequency ranging signal. The second set uses three receiver antennas to measure multiple ranges, effectively providing angular information. It is derived in the paper that for the more complete sensor set, the error in the estimation of the relative state is a function of the pseudorange error, the inter-satellite distance, and the receiver antenna baselines. By varying these variables, conditions are found for which the observations obtained using the first sensor set result in relative state estimation and observability comparable to those obtained with the more complete sensor set. This offers potential reductions in cost and complexity for certain mission scenarios.","formation flying; inter-satellite ranging; noise; estimation; observability","en","conference paper","International Astronautical Federation","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:10c08a16-ebe8-4926-b090-31262628923e","http://resolver.tudelft.nl/uuid:10c08a16-ebe8-4926-b090-31262628923e","Experimental and Numerical Quantification of Radial Flow in the Root Region of a HAWT","Akay, B.; Ferreira, C.S.; Van Bussel, G.J.W.; Herraez, I.","","2012","This paper explores the evolution of radial flow in a Horizontal Axis Wind Turbine (HAWT) blade root region. The radial flow is analyzed in the potential flow and viscous flow regions. An experiment carried out by means of stereo Particle Image Velocimetry to measure the velocity field produced by a HAWT blade. While the radial flow in the potential flow region was obtained from the measurements, the radial flow in the boundary layer was derived from CFD. By the direct observations obtained from the experiment, an insight is gained about the nature of the radial flow in the suction side of the blade as well as in the near wake. An outboard radial flow motion is observed in the root region. This tendency of the flow changes dramatically when it reaches the maximum chord position of the blade, where the radial flow moves inboard. The trace of the viscous region due to merging of the boundary layers and trailing vorticity are observed clearly in the radial velocity and vorticity distributions at 135º azimuth angle of the blade. In the viscous flow region the radial flow is more pronounced than in the potential flow region. The performed CFD simulations are able to predict the vortex formation in the maximum chord region and its interaction with the nacelle.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:bc03804e-378a-447b-a6d5-1d0879f5d1b8","http://resolver.tudelft.nl/uuid:bc03804e-378a-447b-a6d5-1d0879f5d1b8","An abstraction hierarchy and functional model of airspace for airborne trajectory planning support","Abeloos, A.L.M.; Van Paassen, M.M.; Mulder, M.","","2003","","situation awareness; ecological interface design; abstraction hierarchy; functional modelling","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d7fc9b48-71f7-46d0-b8d5-50e25dab3a88","http://resolver.tudelft.nl/uuid:d7fc9b48-71f7-46d0-b8d5-50e25dab3a88","Actuator disc momentum theory for low lambda rotors","Sorensen, J.N.; Van Kuik, G.A.M.","","2009","","","en","conference paper","Euromech","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:6ba3cf36-2be9-49fa-9d3e-d0c8fd9c5d01","http://resolver.tudelft.nl/uuid:6ba3cf36-2be9-49fa-9d3e-d0c8fd9c5d01","Characterization of noise sources in a rod-airfoil configuration by means of Time-Resolved Tomographic PIV","Lorenzoni, V.; Violato, D.; Scarano, F.","","2010","Time-resolved Tomographic PIV was used to characterize the flow around the leading edge of a NACA 0012 airfoil in rod-airfoil configuration at ReD = 3500. The volumetric approach at relatively high temporal resolution allows the measurement of the evolution of the 3D vortical structures constituting the Karman wake of the rod at interaction with the airfoil. The pressure gradient is reconstructed exploiting the definition of Lagrangian derivative and the pressure field is obtained by spatial integration of the Poisson equation. Time-correlation is performed between the aeroacoustic sources of Curle's aeroacoustic analogy and Vortex Sound Theory represented by respectively, time derivative of the pressure fluctuations at the surface and time derivative of the Lamb vector in the surrounding flow. The region of highest correlation is located underneath the airfoil leading edge and appears not to coincide with the region of most intense vortex stretching.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:a6e0f41c-fb92-4638-b9a8-9b2df345cd48","http://resolver.tudelft.nl/uuid:a6e0f41c-fb92-4638-b9a8-9b2df345cd48","Comparison of two mathematical models of the kite for Laddermill sail simulation","Podgaets, A.R.; Ockels, W.J.","","2007","Laddermill sail is an innovative approach to propel the ship with the power generated by kites. The first Laddermill system is currently being designed however existing mathematical models of the system produce different optimal recommendations. Thus a decision has been made to step back and to take a closer look at the mathematical models of Laddermill sail. Each kite is considered a single rigid body as is the ship. It’s been found that the differences between results might come from the fact that the two models possess features of the kite that cannot be combined in the rigid wing approach. More adequate modelling of controlling mechanisms will allow adequate modelling of Laddermill sail as a whole.","Laddermill; Laddermill sail; kiteboat; kitesail","en","conference paper","IAENG International Association of Engineers","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:58d76fff-a25e-4254-b642-36257ad1b8bd","http://resolver.tudelft.nl/uuid:58d76fff-a25e-4254-b642-36257ad1b8bd","Artificial Neural Networks for SCADA Data based Load Reconstruction (poster)","Hofemann, C.; Van Bussel, G.J.W.; Veldkamp, H.","","2011","If at least one reference wind turbine is available, which provides sufficient information about the wind turbine loads, the loads acting on the neighbouring wind turbines can be predicted via an artificial neural network (ANN). This research explores the possibilities to apply such a network not only within a wind park but on turbines located at different sites. Following the idea to develop a tool to forecast the particular loads of any wind turbine in the field without the need to install additional measuring systems, a model has been developed needing only signals contained in the Supervisory Control and Data Acquisition (SCADA) data as input signals.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:5b03b1e9-700d-4025-b955-2233d4834986","http://resolver.tudelft.nl/uuid:5b03b1e9-700d-4025-b955-2233d4834986","Instantaneous planar pressure field determination around a square-section cylinder based on time resolved stereo-PIV","De Kat, R.; Van Oudheusden, B.W.; Scarano, F.","","2008","","","en","conference paper","Calouste Gulbenkian Foundation","","","","","","","","Aerospace Engineering","","","","",""
"uuid:005162c6-e131-4f6b-ba20-1615c77502fd","http://resolver.tudelft.nl/uuid:005162c6-e131-4f6b-ba20-1615c77502fd","Analysis of inflow parameters using LiDARs","Giyanani, A.H.; Bierbooms, W.A.A.M.; Van Bussel, G.J.W.","","2014","Remote sensing of the atmospheric variables with the use of LiDAR is a relatively new technique for wind resource assessment and oncoming wind prediction in wind energy. The validation of LiDAR measurements and comparisons with other sensing elements thus, is of high importance for further applications of the data. A measurement campaign with two vertical scanning pulsed LiDARs and met mast measurements was used here for comparison of inflow wind variables from LiDAR, sonic and cup anemometers. A comparison of the wind directions, wind speed and wind shear was performed to determine the validity of LiDAR measurements in wind energy applications. The LiDAR measurements correlated well with met mast measurements and a major cause for wind direction bias was found.","","en","conference paper","EAWE European Academy of Wind Energy","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:bacf3e21-1cae-4722-93e2-55f15fdcd3ed","http://resolver.tudelft.nl/uuid:bacf3e21-1cae-4722-93e2-55f15fdcd3ed","The Laddermill: Work in progress","Ockels, W.J.; Lansdorp, B.; Breukels, J.; Spierenburg, G.J.","","2004","","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e1c9e380-5170-45dc-a10c-664e1b388576","http://resolver.tudelft.nl/uuid:e1c9e380-5170-45dc-a10c-664e1b388576","Optimal Cross-Wind Towing and Power Generation with Tethered Kites","Williams, P.; Lansdorp, B.; Ockels, W.","","2007","Non-powered flight vehicles such as kites can provide a means of transmitting wind energy from higher altitudes to the ground via tethers. Although there have been many proposals for systems to extract wind energy from higher altitudes, this paper focuses on the use of a light lifting body at the end of a tether to generate useful power. Two major configurations are studied: 1) the kite is used to tow a ground vehicle in the cross-wind direction, 2) the kite is flown to generate power using a ground generator. In both cases, the useful work done by the kite is transmitted to the ground through the tether. Both applications require automatic control of the kite. A simplified system model is used to study the nature of the optimal trajectories of the system for different wind speeds. Numerical results illustrate that optimal power generation requires complex three-dimensional kite trajectories, whereas cross-wind towing requires much simpler trajectories. A feedback tracking controller is demonstrated for tracking the kite trajectories in the presence of unsteady winds.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:cce0e6af-b404-4519-a037-178770fb8778","http://resolver.tudelft.nl/uuid:cce0e6af-b404-4519-a037-178770fb8778","Propeller slipstream investigation using the fokker F27 wind tunnel model with flaps deflected","Schroijen, M.J.T.; Veldhuis, L.L.M.; Singerland, R.","","2008","","Propeller; nstallation; ertical tail side wash","en","conference paper","Optimage Ltd. on behalf of the ICAS","","","","","","","","Aerospace Engineering","","","","",""
"uuid:680de920-96e0-4722-9e52-df3dcdc364d9","http://resolver.tudelft.nl/uuid:680de920-96e0-4722-9e52-df3dcdc364d9","Model for Predicting the Liftetime of a Hall Effect Thruster","Vrebosch, T.M.F.; Misuri, T.; Andrenucci, M.; Zandbergen, B.T.C.","","2012","Erosion of the acceleration channel is the main lifetime limiting factor for Hall Effect Thrusters (HETs). Impacting ions damage the wall insulation that protects the magnetic circuitry from the plasma. To improve HET technology, it is necessary to simulate plasma behavior inside the channel, and associated erosion rates. This work presents a 2-dimensional Particle-in-Cell model, developed to predict channel wall erosion in Hall thrusters, using an SPT-100 as reference thruster, and providing estimations in good agreement with experimental values. The model allows for evaluation of different erosion mechanisms, both combined as individually. From different simulation results, erosion due to the sheath conditions has proven to be the dominant source for wall erosion.","","en","conference paper","AAAF-ESA-CNES","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:8bf4cb4f-60c9-4164-b396-d867f5938d9b","http://resolver.tudelft.nl/uuid:8bf4cb4f-60c9-4164-b396-d867f5938d9b","Experimental Study on the Body Force Field of Dielectric Barrier Discharge Actuators","Kotsonis, M.; Ghaemi, S.; Giepman, R.H.M.; Veldhuis, L.L.M.","","2010","An experimental investigation on thrust and body force of Dielectric Barrier Discharge (DBD) /plasma actuators aimed at low power flow control applications is presented. A parametric study on thrust is conducted for a wide range of geometrical configurations as well as several electrical operational conditions. Direct measurements of the induced thrust are taken using a highly sensitive load cell. Simultaneous readings of current and voltage are also performed, providing the power consumption. Furthermore a novel technique for determination of the spatial distribution of the body-force is proposed, developed and tested. The technique involves the use of a high-speed PIV system to resolve all terms of the Navier-Stokes equation representation of the flow field including body force. Results reveal the existence of an explicit relation between voltage, thrust and consumed power. Furthermore the influence of the geometrical configuration of the actuator on the thrust is shown. The body force obtained with the proposed technique agrees well with the thrust measurements.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:a6142329-ebce-4f0d-80a6-847e35d6db36","http://resolver.tudelft.nl/uuid:a6142329-ebce-4f0d-80a6-847e35d6db36","Extending generalized hough transform to detect 3D objects in laser range data","Khoshelham, K.","","2007","Automated detection and 3D modelling of objects in laser range data is of great importance in many applications. Existing approaches to object detection in range data are limited to either 2.5D data (e.g. range images) or simple objects with a parametric form (e.g. spheres). This paper describes a new approach to the detection of 3D objects with arbitrary shapes in a point cloud. We present an extension of the generalized Hough transform to 3D data, which can be used to detect instances of an object model in laser range data, independent of the scale and orientation of the object. We also discuss the computational complexity of the method and provide cost-reduction strategies that can be employed to improve the efficiency of the method.","laser scanning; point cloud; object recognition; 3D generalized hough transform; automation","en","conference paper","International Society for Photogrammetry and Remote Sensing","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:927a1c12-ae63-4f6f-b2a1-14ac6da22e2e","http://resolver.tudelft.nl/uuid:927a1c12-ae63-4f6f-b2a1-14ac6da22e2e","Design and testing of a remotely controlled surfkite for the Laddermill","Lansdorp, B.; Remes, B.D.W.; Ockels, W.","","2005","This paper presents the design and testing of a remotely controlled surfkite for the Laddermill. The Laddermill is a novel concept to generate electricity from high altitude winds. It generates electricity by pulling a rope from a generator, with lift generated by kites. Part of the rope that is connected to the kites is wound around the generator. The kites pull the rope from the generator, thus driving it. Subsequently the kites fly down in a configuration that generates significantly less lift than during the ascent. This way the tether is retrieved and the process is repeated. The Laddermill concept allows very large single unit powers. For an early demonstration of the Laddermill principle, a commercially availably Peter Lynn surfkite is used. This surfkite is radio controlled, by means of drag creating actuators on the wing tips. This paper presents the actuator design and results of testing of the surfkite. Preliminary results of generation of Laddermill energy are also presented.","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d6560f86-ada8-4a47-99fd-1d7d2f872d36","http://resolver.tudelft.nl/uuid:d6560f86-ada8-4a47-99fd-1d7d2f872d36","Design of an Ecological Flow-based Interface for 4D Trajectory Management in Air Traffic Control","Pinto, J.; Klomp, R.E.; Borst, C.; Van Paassen, M.M.; Mulder, M.","","2015","The concept of trajectory-based operations as proposed by SESAR and NextGen seeks to increase airspace efficiency and capacity by introducing time as an explicit control variable. Such form of operations lean heavily on the introduction of higher levels of automation to support the human air traffic controller in performing this new task. In previous research, and following the ecological interface design paradigm, a constraint-based decision support tool has been developed to visualize safe and unsafe fields of travel for rerouting the 4D trajectories of individual aircraft. A human-in-the-loop experiment showed that although the interface visualizes the boundaries between safe and unsafe actions, the quality of control in terms of robustness was mainly dependent on the level of expertise of the human controller. Following these findings, the goal of this study has been twofold: 1) to explicitly integrate the attributes of robust control actions into the constraint-based visualization, and 2) to enable flow-based (multi-aircraft) operations with the decision-support tool which is more in line with the mental model of expert controllers. As a result, a metric for the evaluation of robustness has been developed and three different types of structure-based control abstractions have been identified which have been integrated into the tool. Future work will focus on a human-in-the-loop experiment in order to evaluate the effectiveness of these two new additions.","air traffic management; ecological interface design; trajectory-based operations; robustness; flow-based control; human-machine interaction","en","conference paper","","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:1573407d-e3f4-420f-8231-6d3eb674641e","http://resolver.tudelft.nl/uuid:1573407d-e3f4-420f-8231-6d3eb674641e","Reflection seismology systems for planetary geology: A feasibility study","Batenburg, P.A.W.; Gill, E.K.A.; Drijkoningen, G.G.; Foing, B.H.; Toxopeus, G.","","2009","A feasibility study is conducted to determine whether reflection seismology systems can be used for planetary geology research. The focus is on systems with up to 20,000 seismic detectors, such as used today in Earth geological research and energy companies. The study follows a top-down systems engineering end-user approach starting with the identification of possible applications of a seismic system. These applications (scenarios) have been determined with the help of geologists. These scenarios are transformed into system requirements using geophysicists’ methods. Among these methods are simulations where the seismic image was simulated of subsurface structures based on models. Concepts are created based on current reflection seismology technologies and key areas, which require improvements for a space application. To keep the end result as broadly applicable as possible, no specific mission or scenario was used as reference. Instead, a set of possible missions was drafted. Suitable concepts will be selected for each mission type. At the time of writing (September 2009), the system requirements are determined and various concepts are created.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:a5d2398b-1199-41a6-ae34-d20f4a4428b1","http://resolver.tudelft.nl/uuid:a5d2398b-1199-41a6-ae34-d20f4a4428b1","Mission Design of the Dutch-Chinese FAST Micro-Satellite Mission","Maessen, D.C.; Guo, J.; Gill, E.; Laan, E.; Moon, S.; Zheng, G.T.","","2009","The paper treats the mission design for the Dutch-Chinese FAST (Formation for Atmospheric Science and Technology demonstration) mission. The space segment of the 2.5 year mission consists out of two formation flying micro-satellites. During the mission, new technologies will be demonstrated and, using spectropolarimeter and altimeter payloads on both spacecraft, observations will be performed characterizing atmospheric aerosols and seasonal variations of height profiles in the cryosphere. The mission is divided into four phases, each with a different orbital geometry. The rationale for and the orbital geometry during these phases as well as the transitions between the phases are treated in detail. A major complication to the mission design is the amount of data that can be sent to the ground. Since only two moderately capable ground stations, one in Delft and one in Beijing, are baselined, as much data processing as possible has to be performed onboard to allow high duty factors for the science payloads. When this is not possible, alternative payload operation modes have to be sought with which maximum scientific data return can be obtained through as little payload operation as possible. Both options are dealt with in the paper.","FAST; formation flying; mission design; scientific data return","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:5213f0c5-e83e-4fed-90ab-7f97fdd86b08","http://resolver.tudelft.nl/uuid:5213f0c5-e83e-4fed-90ab-7f97fdd86b08","Temperature effect on the static behaviour of adhesively-bonded metal skin to composite stiffener","Teixeira De Freitas, S.; Sinke, J.","","2015","The purpose of this research is to study the effect of temperature on the static behavior of an hybrid structure consisting of adhesively bonded Fiber Metal Laminate skin to a composite stiffener. This hybrid structure was tested using stiffener pull-off tests, which is a typical set-up used to simulate the structural behaviour of full-scale components subject to out-of-plane loading. The failure mechanism is very similar at the three temperatures tested: -55C, Room Temperature and +100C. The damage initiates at the central noodle of the composite stiffener. Unstable delamination then propagates from the noodle to the tip of the stiffener foot, preferably through the stiffener foot plies. However, the maximum load and corresponding displacement increase significantly with temperature. At +100C the maximum load increases approximately 15% to 30% when compared to RT. At -55C the maximum load decreases approximately 50% to 60% when compared to RT. No influence of the adhesive was observed in the maximum load values, since no damage occurs at the adhesive bondline. This research identifies that the composite stiffener is the weakest link of the hybrid bonded structure metal-skin-to-composite-stiffener and not the adhesive bondline. This holds for static loading in a wide temperature range.","adhesive bonding; skin-to-stiffener connection; composite-to-metal joints; hybrid structures","en","conference paper","ABSM","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:2ad9dbac-9f59-44d3-988f-9fa64dc206ba","http://resolver.tudelft.nl/uuid:2ad9dbac-9f59-44d3-988f-9fa64dc206ba","A comparative analysis of project management and systems engineering techniques in CubeSat projects","Elstak, J.; Amini, R.; Hamann, R.J.","","2009","","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:53f19ab4-a579-4ca1-a914-241d8ccafe7e","http://resolver.tudelft.nl/uuid:53f19ab4-a579-4ca1-a914-241d8ccafe7e","Understanding the Fatigue Behavior of FML Structures and Materials under Complex Variable Amplitude Loading","Alderdiesten, R.; Benedictus, R.; Khan, S.","","2009","This paper presents various failure mechanisms in FMLs, highlights the presence or absence of interaction effects, and describes how the failure mechanisms can be described for predicting damage growth under arbitrary complex load spectra.","","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:60864d18-d54a-4803-b1fd-492db07a5743","http://resolver.tudelft.nl/uuid:60864d18-d54a-4803-b1fd-492db07a5743","Development of a Multi-Event Trajectory Optimization Tool for Noise-Optimized Approach Route Design","Braakenburg, M.L.; Hartjes, S.; Visser, H.G.; Hebly, S.J.","","2011","This paper presents preliminary results from an ongoing research effort towards the development of a multi-event trajectory optimization methodology that allows to synthesize RNAV approach routes that minimize a cumulative measure of noise, taking into account the total noise effect aggregated for all inbound flight movements taking place within an operational year. This new development is an extension of a tool called NOISHHH which was developed earlier for the synthesis of single-event noise abatement RNAV trajectories into and out of airports. Although the presented numerical examples pertain to a specific airport in the Netherlands, viz. Rotterdam the Hague airport, this study focuses on the development of a generic methodology that can be applied to any given airport. Initial application of the adapted optimization framework to the design of noise abatement RNAV approach routes at Rotterdam The Hague airport reveals a significant potential for reducing the number of people highly annoyed due to annual noise exposure relative to the existing situation.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:852e4a0f-512c-48fd-8cc7-ba69a5bece96","http://resolver.tudelft.nl/uuid:852e4a0f-512c-48fd-8cc7-ba69a5bece96","An agent-based model to study effects of team processes on compliance with safety regulations at an airline ground service organization","Sharpanskykh, A.; Haest, R.","","2015","Maintaining high levels of safety under conditions of ever increasing air traffic is a challenging task. Failures to comply with safety-related regulations are often considered to be important contributors to safety occurrences. To address the issue of compliance, approaches based on external regulation of the employees’ behavior were proposed. Unfortunately, an externally imposed control is often not internalized by employees and has a short-term effect on their performance. To achieve a long-term effect, employees need to be internally motivated to adhere to regulations. Theories from social sciences propose that team processes play an important role in the dynamics of individual motivation. In this paper an agent-based model is proposed, by which the impact of social interaction and coordination in teams of platform employees on their individual motivation and compliance with safety regulations at an airline ground service organization are explored. The model was simulated and partially validated by a case study performed at a real airline ground service organization. The model was able to reproduce behavioral patterns of compliance of the platform employees in this study.","compliance; agent-based model; motivation; cognitive models; social contagion","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:bed35efc-cd0b-411b-8e5e-56f5bf2684bc","http://resolver.tudelft.nl/uuid:bed35efc-cd0b-411b-8e5e-56f5bf2684bc","Navier-Stokes simulations in gappy PIV data","Sciacchitano, A.; Dwight, R.P.; Scarano, F.","","2012","Velocity measurements conducted with particle image velocimetry (PIV) often exhibit regions where the flow motion cannot be evaluated. The principal reasons for this are the absence of seeding particles or limited optical access for illumination or imaging. Additional causes can be laser light reflections and unwanted out-of-focus effects. As a consequence, the velocity field measured with PIV contains regions where no velocity information is available, i.e. gaps. This work investigates the suitability of using the unsteady incompressible Navier-Stokes equations to obtain accurate estimates of the local transient velocity field in small gaps; the present approach applies to time-resolved two-dimensional experiments of incompressible convection dominated flows. The numerics are based on a finite volume discretization with partitioned time-stepping to solve the governing equations in the incompressible regime. The measured velocity distribution at the gap boundary is taken as time-varying boundary condition, and an approximate initial condition (I.C.) inside the gap is obtained via low-order spatial interpolation of the velocity at the boundaries. The influence of this I.C. is seen to diminish over time, as information is convected through the gap. Due to the form of the equations, no initial or boundary conditions on the pressure are required. The approach is evaluated by a time-resolved experiment where the true solution is known a-priori. The results are compared with a boundary interpolation approach. Finally, an application of the technique to an experiment with a gap of complex shape is presented.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:cedaa7bc-393b-416d-8a4a-ad3d9fc408fd","http://resolver.tudelft.nl/uuid:cedaa7bc-393b-416d-8a4a-ad3d9fc408fd","A Semi-Continuous Formulation for Goal-Oriented Reduced-Order Models","Cheng, L.; Mattei, S.; Fick, P.W.; Hulshoff, S.J.","","2014","A semi-continuous formulation is introduced for finding bases which minimise the error in a specific output functional of a reduced-order model. The formulation is advantageous in that it can be easily applied to nonlinear problems and functionals. A general description of the approach is given, then explicit formulations are derived for the convection-diffusion and Burgers equations. Numerical results are given for both linear and non-linear functionals. These show substantial reductions in error, depending on the functional considered. Optimisation of bases for a reduced-order model based on an approximated governing equation is also described, for which large increases in accuracy are obtained.","reduced-order models; POD; optimisation","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:a7c93ec4-7000-4bba-867b-b58e34de563e","http://resolver.tudelft.nl/uuid:a7c93ec4-7000-4bba-867b-b58e34de563e","An Analytical Model to Extract Wind Turbine Blade Structural Properties for Optimization and Up-scaling Studies","Ashuri, T.; Van Bussel, G.J.W.; Zaayer, M.B.; Van Kuik, G.A.M.","","2010","A wind turbine blade has a complex shape and consists of different elements with dissimilar material properties. To do any aeroelastic simulation, the structural properties of the blade such as stiffnesses and mass per unit length should be known in advance, and extracting these properties is a difficult task. This paper presents an analytical model to extract these structural properties in a simple way. It starts with calculating an equivalent material property of the cross section using weighting method. Then the centroid of each section is obtained. Next the second moment of inertia of each element relevant to its local coordinates system is calculated and transferred to the centroid of the section using parallel axis theorem. A coordinate transformation is employed to rotate these second moment of inertias around any arbitrary axis. Finally, flapwise and edgewise stiffnesses are found by multiplying the equivalent modulus of elasticity to the second area moment of inertia in each section. Mass per unit length is calculated by multiplying the equivalent density to the real area of each section. The method is verified with the structural properties of a commercial 660 kW wind turbine blade. Despite the simplicity of the method the results show a good agreement.","wind turbine blade; structural properties; analytical model","en","conference paper","European Wind Energy Association","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:c4d442e0-91ff-4d03-a7a0-f94aa7f30919","http://resolver.tudelft.nl/uuid:c4d442e0-91ff-4d03-a7a0-f94aa7f30919","A Methodology to Enable Automatic 3D Routing of Aircraft Electrical Wiring Interconnection Systems","Zhu, Z.; La Rocca, G.; Van Tooren, M.J.L.","","2015","Harness 3D routing in aircraft Electrical Wiring Interconnection System (EWIS) design is very complex because of both the intrinsic complexity of EWIS and the increasing number of design constraints. The complexity hinders the improvement of the design efficiency and makes the design error prone. Considering that many harness components are selected from catalogues and the design work is largely repetitive and mostly rule based, there are many opportunities to automate a significant part of the design process. Nevertheless, none or very limited solutions to automate the 3D routing have been found. Aiming for the automation of harness 3D routing, in this research, an innovative approach has been proposed that models and solves the 3D routing problem as an optimization problem. The challenge to solve above optimization problem is that the number of design variables, namely the number of clamping points, is not known a priori. The number is actually an output of the 3D routing. In order to handle this challenge, a two-step, hybrid optimization strategy has been devised. The first step, called Initialization, generates a preliminary harness definition using a road map based path finding method without knowing the number of design variables. The second step, called Optimization uses conventional optimization method to refine the preliminary harness definition while satisfying all design constraints. This approach has been implemented into a software application and several cases have been executed to validate the system functionality. The results have demonstrated that the tool is capable of handling cases of representative complexity and design constraints and deliver 3D harness models in full automation.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:c949fb3a-d868-47d0-ad21-c6574c439c81","http://resolver.tudelft.nl/uuid:c949fb3a-d868-47d0-ad21-c6574c439c81","Deterioration estimation of artworks by means of a novel: 3D-hyperspectral imaging system (poster)","Papadakis, V.; Groves, R.M.; Tornari, V.; Portales, C.; Borreman, A.; Vermeiren, J.; Ward, J.D.; Ribes-Gomez, E.","","2015","","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:7a8981d6-ce65-4a63-97c4-78bfe735e27a","http://resolver.tudelft.nl/uuid:7a8981d6-ce65-4a63-97c4-78bfe735e27a","Variable Amplitude Fatigue of FMLs On Developing a Mechanistic Understanding","Rans, C.; Alderdiesten, R.; Benedictus, R.; Khan, S.","","2009","Presentation on conference","","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:788dd88a-dae3-4506-abfa-0aae7b2b4450","http://resolver.tudelft.nl/uuid:788dd88a-dae3-4506-abfa-0aae7b2b4450","Sensor Fusion Applied To Shape Sensing: Theory and Numerical Proof-of-Concept (poster)","De Mooij, C.; Martinez, M.; Benedictus, R.","","2015","Existing shape sensing methods use individual sensor types, determining either strain or displacement well, but not both. More accurate shape sensing could improve load estimation, necessary for accurate life assessment of the structure.","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a9a68452-5a77-431f-8377-7bc57e24d6e7","http://resolver.tudelft.nl/uuid:a9a68452-5a77-431f-8377-7bc57e24d6e7","Rosenbrock time integration for unsteady flow simulations","Blom, D.S.; Bijl, H.; Birken, P.; Meister, A.; Van Zuijlen, A.H.","","2013","This contribution compares the efficiency of Rosenbrock time integration schemes with ESDIRK schemes, applicable to unsteady flow and fluid-structure interaction simulations. Compared to non-linear ESDIRK schemes, the linear implicit Rosenbrock-Wanner schemes require subsequent solution of the same linear systems with different right hand sides. By solving the linear systems with the iterative solver GMRES, the preconditioner can be reused for the subsequent stages of the Rosenbrock-Wanner scheme. Unsteady flow simulations show a gain in computational efficiency of approximately factor three to five in comparison with ESDIRK.","Rosenbrock time integration; higher order time integration; unsteady flow simulations; ESDIRK; Rosenbrock-Wanner methods","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:1e456421-197e-4fef-8528-bed022ea4a41","http://resolver.tudelft.nl/uuid:1e456421-197e-4fef-8528-bed022ea4a41","Piloted Simulator Evaluation Results of New Fault-Tolerant Flight Control Algorithm","Lombaerts, T.J.J.; Smaili, M.H.; Stroosma, O.; Chu, Q.P.; Mulder, J.A.; Joosten, D.A.","","2010","A high fidelity aircraft simulation model, reconstructed using the Digital Flight Data Recorder (DFDR) of the 1992 Amsterdam Bijlmermeer aircraft accident (Flight 1862), has been used to evaluate a new Fault-Tolerant Flight Control Algorithm in an online piloted evaluation. This paper focuses on the piloted simulator evaluation results. Reconfiguring control is implemented by making use of Adaptive Nonlinear Dynamic Inversion (ANDI) for manual fly by wire control. After discussing the modular adaptive controller setup, the experiment is described for a piloted simulator evaluation of this innovative recon- figurable control algorithm applied to a damaged civil transport aircraft. The evaluation scenario, measurements and experimental design, as well as the real-time implementation are described. Finally, reconfiguration test results are shown for damaged aircraft models including component as well as structural failures. The evaluation shows that the FTFC algorithm is able to restore conventional control strategies after the aircraft configuration has changed dramatically due to these severe failures. The algorithm supports the pilot after a failure by lowering workload and allowing a safe return to the airport. For most failures, the handling qualities are shown to degrade less with a failure than the baseline classical control system does.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:e00cec8f-7e48-4ee2-835d-402939b52411","http://resolver.tudelft.nl/uuid:e00cec8f-7e48-4ee2-835d-402939b52411","TPMagic, a universal airport surface traffic planning analysis and optimization tool","Roling, P.C.","","2011","Adding runways and taxiways is a way of solving capacity problems at major airport. As this also increases the intensity of airport ground operations, safety and efficiency might be compromised. This is one of the main reasons why a significant amount of research has been done in this field, such as research with respect to Advanced Surface Movement Guidance and Control Systems. A taxi planning model developed at the TU Delft uses MILP techniques, combined with pre and processing to allow simulation and optimization of the routing of aircraft on taxiways for major airports. A study of Hartsfield–Jackson Atlanta International Airport shows the benefits an Advanced Surface Movement Guidance and Control Systems can have.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerospace Structures & Design Methodology","","","",""
"uuid:8f2dae6a-6d21-4660-b306-ccdadd7970a9","http://resolver.tudelft.nl/uuid:8f2dae6a-6d21-4660-b306-ccdadd7970a9","Simplified fatigue assessment of offshore wind support structures accounting for variations in a farm","Michalopoulos, M.; Zaayer, M.B.","","2015","Provided the significant contribution of support structures to the capital expenditures of offshore wind, optimisation schemes are often developed to address the need for tailored design of different structures in one farm. A crucial aspect of them is, among others, the Fatigue Limit State (FLS)1234 .To this direction, research is conducted on the response of the structure to cyclic loading in the frequency-domain567 . However, the complexity and the need for advanced software (finite element and/or aero-elastic codes) often limit the flexibility. As a consequence, the design process is not facilitated significantly. The focus of this study is principally placed on the impact that variations in an offshore wind farm (OWF) have on the support structures, particularly on their resistance to cumulative damage caused by wind and wave loading. The vital requirement is therefore that the procedure is computationally affordable to ensure applicability for the early design phase of multiple structures. The goal of this study is to develop such a procedure.","","en","conference paper","EWEA European Wind Energy Association","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:a92e3d63-119c-407d-8c5b-64a2801e5a07","http://resolver.tudelft.nl/uuid:a92e3d63-119c-407d-8c5b-64a2801e5a07","Size effect on wind turbine blade's design drivers","Ashuri, T.; Zaayer, M.B.","","2008","","","en","conference paper","European Wind Energy Association EWEA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e246a643-6dba-4434-8d40-5b0071477b9a","http://resolver.tudelft.nl/uuid:e246a643-6dba-4434-8d40-5b0071477b9a","Multi-agent testbed for distributed space systems","Osuman, A.; Guo, J.; Gill, E.K.A.","","2010","Several industries are involved in the development of distributed systems, testbeds are needed to simulate the real world challenges that face the distributed systems. Presently, there are a number of testbeds in the world with very distinctive characteristics. Delft University of Technology is involved in the development of distributed space systems, a testbed will be build to aid this development. It is required that the robots in this testbed imitate a miniature spacecraft as closely as possible, while on the other hand cost and required man-hours should stay as low as possible. Using these performance measures, a list of design options have been traded-off against each other in a quantitative trade-off. The winning design has a set of robots that rest on planar-ball-bearings. They are actuated by four propellers configured such that the robots are holonomic, their sensor suit consists of a rate gyroscope, accelerometer, and radio-ultrasonic rangers that can be used in combination with trilateration to determine the position. This testbed is currently under construction.","","en","conference paper","International Astronautical Federation","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:bf7d8c38-d5c7-4378-a6bf-2e3129740dd8","http://resolver.tudelft.nl/uuid:bf7d8c38-d5c7-4378-a6bf-2e3129740dd8","Summary of Data Analysis of the YES2 Tethered SpaceMail Experiment","Kruijff, M.; Van der Heide, E.J.; Ockels, W.J.; Gill, E.K.A.","","2008","The 2nd Young Engineers' Satellite (YES2) is a 36 kg student-built experiment that piggybacked on the Foton-M3 microgravity platform in September 2007. YES2 intended to demonstrate tethered SpaceMail, a concept for frequent sample return originally proposed for the International Space Station (ISS). This paper summarized the YES2 mission results. The planned tether deployment included a unique two-stage approach, a tether swing of 45 degrees and a capsule release from the bottom of the tether for increased landing precision. After a successful first stage, during the second stage the tether deployed to its full length of 31.7 km rather than the target length of 30 km due to an electrical problem. It was released at the proper time close to the nominal release point, sending Fotino some 1250 km upstream of the nominal landing point. The capsule was not yet recovered. The YES2 mission had the following scientific objectives: reconstruction of the deployment trajectory; estimation of the capsule trajectory and determination of the landing spot; assessment of the closed-loop control performance and potential landing accuracy; assessment of the deployer hardware performance for the SpaceMail application; study of tether physics and suitability of simulations and testing for planning future tether missions. All the tether mission objectives could be achieved, the novel deployment features were successfully demonstrated, any problem occurring was identified and solutions proposed. The quantity and quality of the data allows for improved understanding of tether dynamics and recommendation for future activities. Based on the lessons learned a sequel mission can be defined with promising perspectives.","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:fdc1a4e4-c217-42b2-bc69-a9ef724e89bc","http://resolver.tudelft.nl/uuid:fdc1a4e4-c217-42b2-bc69-a9ef724e89bc","High Precision Beam Diagnostics for Ion Thrusters","Van Reijen, B.; Koch, N.; Lazurenko, A.; Weis, S.; Schirra, M.; Genovese, A.; Haderspeck, J.; Gill, E.K.A.","","2011","The Thales diagnostic equipment for ion beam characterization consists of a gridded and single orifice retarding potential analyzer (RPA) and an energy selective mass spectrometer (ESMS). During the development phase of these sensors considerable effort was put into the removal of ion optical effects as well as to ensure equal ion transmission ratios for low and high energetic ions for both devices. To this end simulation software was used to look into the trajectories of ions from a wide range of potential energy, angle of incidence and charge state. The simulations verified effects due to RPA grid misalignment and were the foundation for the development of a single orifice RPA and the adaptation of the ESMS. Experimental testing verified the improved performance of the sensory equipment due to ion trajectory simulation.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:eea9a2e8-f9c3-4b0c-b0d4-a44cde3bf6b1","http://resolver.tudelft.nl/uuid:eea9a2e8-f9c3-4b0c-b0d4-a44cde3bf6b1","Using the Engineering Design Cycle to Develop Integrated Project Based Learning in Aerospace Engineering","Saunders-Smits, G.N.; Roling, P.; Brügemann, V.; Timmer, N.; Melkert, J.","","2012","Over the past four years the Faculty of Aerospace Engineering at Delft University of Technology in the Netherlands has redeveloped its BSc curriculum to mimic an engineering design cycle. Each semester represents a step in the design cycle: exploration; system design; sub-system design; test, analysis & simulation; verification & validation.","","en","conference paper","Loughborough University","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:35db0da5-807d-4e10-9283-8ad3c17e873e","http://resolver.tudelft.nl/uuid:35db0da5-807d-4e10-9283-8ad3c17e873e","Heliodromus: Renewable energy from space","Kuiper, J.M.","","2010","Climate change and the related running out of fossil fuel reserves drive the development of renewable energy sources. To contribute to a solution of these problems, we present the results of a BSc student design synthesis exercise project on Space Based Solar Power (SBSP). A SBSP system generates power in space using solar cells concentrator systems and wireless power transmittance to Earth. Main advantages compared to terrestrial solar conversion systems are a higher surface power density and continuous power supply. The project includes an analysis of the current and future electricity market, its technical performance, the conceptual design of a SBSP system, the economical aspects and sustainability. The SBPS top level requirements are an operational lifetime greater than 10 years, an end of life effective power output on Earth exceeding 1 GW, a launch before 2025 and being cost-competitive with terrestrial energy sources. Besides these top level requirements, numerous derived requirements are established on sustainability, safety and (subsystem) design. The SBPS concept, termed Heliodromus, resulted from a broad study starting with three existing concepts. A systems engineering tradeoff resulted in a new constellation concept: Ten satellites orbiting in Low-Earth Orbit and two satellites orbiting in geostationary Earth orbit each having five mirrors. The performance of Heliodromus was evaluated by the following criterea: overall efficiency, technical readiness levels, energy payback time and total cost. The major losses occur during the initial energy conversion, with only 15% efficiency, by the photovoltaic thin films. Heliodromus is 5 to 10 times more expensive compared to existing Earth based solar farms, both photovoltaic and solar dynamic. The energy payback time is 6 years compared to 3 years for terrestrial solutions. The worst case estimate of Heliodromus' efficiency is 2% which is not sufficient to compete with Earth-based solar systems. However, due to the ongoing rapid developments, an overall efficiency of 10% efficiency is credible in the present decade. The (worst case) electricity cost is 1 $ per kWh compared to 0.1 $ per kWh for a (2010) terrestrial power plant. The cost of Heliodromus is around $98 billion and at this stage it is not price-competitive with fossil or Earth-based renewable energy sources. The required assembly in orbit was never done on the scale required for Heliodromus, therefore it opens totally new fields of research and development. The total efficiency was defined worst case but the improvement of electronic components efficiency will continue. Therefore a factor 5 improvement in the near future is probable, getting Heliodromus closer to becoming market viable.","","en","conference paper","International Astronautical Federation","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:30ad6d6a-c3bb-44ed-9eac-8d973d977dd4","http://resolver.tudelft.nl/uuid:30ad6d6a-c3bb-44ed-9eac-8d973d977dd4","Reducing the controlled flight into terrain risk by human error management","Dijkgraaf, F.C.","","1995","","controlled flight into terrain; human error management; ground proximity warning systems; synthetic/enhanced terrain displays","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:42616303-ea10-41de-ad13-fbce2c1f8739","http://resolver.tudelft.nl/uuid:42616303-ea10-41de-ad13-fbce2c1f8739","A model-based method for reducing the sound speed induced errors in multi-beam echo-sounder bathymetric measurements","Snellen, M.; Siemes, K.; Simons, D.G.","","2009","We present a method for accurately estimating the bathymetry from multi-beam echo-sounder (MBES) travel-time measurements in environments with large variations in the water column sound speeds (both temporally and spatially). In this type of environments the water column sound speeds at the time of the MBES transmission are often not known, preventing a reliable conversion from the measured travel-times to bathymetry. In addition, accurate sound speed information is required for the MBES beamsteering process. Situations where information regarding the prevailing sound speeds is insufficient occur, for example, in estuaries where fresh river water mixes with seawater. The method fully exploits the redundancy in the MBES measurements obtained from the overlap of adjacent swathes. It searches for those water column sound speeds that result in a maximum agreement in the bathymetry along the overlapping swathes. The Gauss-Newton method is employed for the optimization. This method is very efficient, requiring a few iterations only and therefore very well suited for processing the large datasets as typically obtained by the MBES. From simulations it is shown that the method performs well and allows for an almost exact determination of the bathymetry and sound speeds. In principle, the method eliminates the need for sound speed measurements, as long as sufficient overlap exists.","bathymetry; oceanographic techniques; rivers; seafloor phenomena; seawater; underwater sound","en","conference paper","IEEE","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:e8e7ecf2-33a4-460b-8ebc-71b88aaa5650","http://resolver.tudelft.nl/uuid:e8e7ecf2-33a4-460b-8ebc-71b88aaa5650","The Dutch CanSat competition: How 350 secondary school pupils compete to build the most innovative 'satellite' in a soda can","Eerkens, R.H.P.; Van Breukelen, E.; Verhoeven, C.J.M.; Vollebregt, S.; Fitié, A.","","2008","The CanSat competition is intended to give pupils the chance to get practical experience in building complex systems in a multidisciplinary environment. Aerospace is the place where this specific combination of science and engineering emerges. It is not only interesting for scientists and engineering students but also for parents and tutors. This interest and enthusiasm can contribute to change the general attitude of ""engineering is difficult"" to ""engineering is fun"". Pupils with a dormant interest in science and engineering can be stimulated by this project to choose a career in engineering.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:73d59d34-5df7-4b3d-ae59-cf1795b4abff","http://resolver.tudelft.nl/uuid:73d59d34-5df7-4b3d-ae59-cf1795b4abff","Efficient Numerical Calculation of Evaporating Sprays in Combustion Chamber Flows","Schmehl, R.; Klose, G.; Maier, G.; Wittig, S.","","1998","Representing two different conceptual approaches, either Eulerian continuum models or Lagrangian particle models are commonly applied for the numerical description of dispersed two phase flows. Taking advantage of the positive features inherent to each model, a combination approach is presented in this study for the efficient computation of liquid fuel sprays in combustor flows. In the preconditioning stage, Eulerian transport equations for gas phase and droplet phase are solved simultaneously in a block-iterative scheme based on a coarse discretization of spray boundary conditions at the nozzle. Due to the close coupling of both phases, the time expense of this approximate flow field computation is not much higher as for single phase flows. In the refinement stage, Lagrangian droplet tracking is applied with a detailed discretization of initial conditions. To account for complete interaction between gas phase and droplets, gas flow solution and droplet tracking are concatenated by an iterative procedure. In this stage, the numerical description of the spray is enhanced by additional modeling of droplet breakup. Results of numerical simulations are compared with measurements of the two phase flow in a premix duct of a LPP research combustor.","combustor flow; fuel preparation; spray; two-phase flow","en","conference paper","NATO","","","","","","","","Aerospace Engineering","AWEP","","","",""
"uuid:94e53b4f-11c2-4e8f-960f-1a99d1f20832","http://resolver.tudelft.nl/uuid:94e53b4f-11c2-4e8f-960f-1a99d1f20832","3D organization of high-speed compressible jets by tomographic PIV","Violato, D.; Ceglia, G.; Tuinstra, M.; Scarano, F.","","2013","This work investigates the three dimensional organization of compressible jets at high-speed regime by tomographic particle image velocimetry (TOMO PIV). Experiments are conducted at Mach numbers 0.3, 0.9 and 1.1 (underexpanded regime) across the end of the potential core within a large cylindrical domain (1.6Dx8D, with D=22mm the jet diameter). At M=1.1, shock and expansion waves are observed in the potential core between Z/D=2.6 and Z/D=5. The velocity fields are analysed by proper orthogonal decomposition (POD) to investigate the three-dimensional organization of large scale structures. Modal patterns are described based on visualizations of the axial velocity, which, among the velocity components, is the main contributor to the total fluctuating kinetic energy. Azimuthal Fourier decomposition is performed prior to POD to reduce the measurement noise of the extracted modes. At any Mach number, the most energetic modes show energy peaks by the end of the potential core and beyond (Z/D>5). At M=1.1, shock and expansion waves are not detected in the most energetic modes.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:aba42aec-7121-4167-850a-c918fdfedb93","http://resolver.tudelft.nl/uuid:aba42aec-7121-4167-850a-c918fdfedb93","Progress in smart rotor research for wind turbines: Experimental and computational approaches to active aerodynamic control","Barlas, A.K.","","2007","","","en","conference paper","European Academy for Wind Energy EAWE","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a446cd88-e0d6-4e40-84a1-b9804ad92168","http://resolver.tudelft.nl/uuid:a446cd88-e0d6-4e40-84a1-b9804ad92168","Closed-loop control wind tunnel tests on an adaptive wind turbine blade for load reduction","Barlas, A.; Van Wingerden, J.W.; Hulskamp, A.W.; Van Kuik, G.A.M.","","2008","","","en","conference paper","American Institute of Aeronautics and Astronautics AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:00e4a306-07d4-48d2-9fa0-817831f5d435","http://resolver.tudelft.nl/uuid:00e4a306-07d4-48d2-9fa0-817831f5d435","Dual-based a-posteriori error estimation for fluid-structure interaction by the embedded-domain method","Van der Zee, K.G.; Van Brummelen, E.H.; De Borst, R.","","2006","Numerical simulations of fluid-structure interaction typically require vast computational resources. Finite-element techniques employing goal-oriented hp-adaptation strategies could offer a substantial improvement in the efficiency of such simulations. These strategies rely on dual-based a-posteriori error estimates for quantities of interest. However, the free-boundary character of fluid-structure-interaction problems forms a fundamental complication, as it yields the underlying domain unknown a-priori. Instead, the domain comprises part of the solution. Consequently, the well-established generic framework for dual-based error estimation is not applicable. In this work we develop a framework for dual-based a-posteriori error estimation for free-boundary problems such as fluid-structure interaction. The framework is based on the embedded-domain approach and an extension operator which enables the comparison of approximate solutions on distinct domains. Given an approximate fluid and structure solution, we present a dual problem on the corresponding approximate fluid domain. Finally, we employ the dual solution to present an exact error representation formula.","fluid-structure interaction; free-boundary problems; a-posteriori error estimation; goal-oriented error estimation; dual-based error estimation; adaptive finite element method","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2abd2983-b1e5-4195-8ea0-ede18ddce5ea","http://resolver.tudelft.nl/uuid:2abd2983-b1e5-4195-8ea0-ede18ddce5ea","Error analysis of 3D shearography using finite-element modelling","Goto, D.T.; Groves, R.M.","","2010","This paper describes the development of an opto-mechanical simulation of a complete shearography system, including the shearography instrument, the samples and the test environment. This simulation is applied to the measurement of 3D strains in engineering samples. The samples are a cylinder loaded by internal pressure and a flat plate under axial load. Finite elements models are used to obtain the displacements fields. A 3D shearography instrument consisting of a laser and four cameras has been simulated using the optical model. Combining the finite elements and optical simulations allows phase maps to be generated, which are the predictions for measurements using the complete test setup. Errors due to sample material properties, loading inaccuracy and dimensional tolerances are included in the model and this allows the calculation of phase maps at the minimum and maximum error limits. The simulation through path lengths and the simulation by inverted shearography processing provide similar results and the difference is associated with the approximation introduced by the sensitivity vector.","3D Shearography; strain measurement; finite element model; error analysis","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Optical Non-Destructive Testing Laboratory","","","",""
"uuid:a4882e51-6f1c-4d2e-84e1-b98732da183d","http://resolver.tudelft.nl/uuid:a4882e51-6f1c-4d2e-84e1-b98732da183d","Fire risk assessment: The role of hyperspectral remote sensing","Maffei, C.; Menenti, M.","","2010","The increasing demand for effective forest fire prevention instruments has faced operational and future Earth observation instruments with the challenge of producing updated and reliable maps of vegetation moisture. Various empirical band-ratio indexes have been proposed so far, based on multispectral remote sensing data, that have been found to be related to vegetation moisture expressed in terms of equivalent water thickness (EWT), which is defined as the weight of liquid water per unit leaf area. More sophisticated retrieval methodologies can be adopted when hyperspectral data are available, e.g. based on spectral curve fitting in selected water absorption bands or radiative transfer model inversion, allowing for better estimates of EWT. Problems arise with the evaluation of fuel moisture content (FMC), which is the percentage weight of water per unit of oven-dried leaf weight, due to its weak signal in vegetation spectrum. FMC is essential in fire models, and it is not interchangeable with EWT. Basing on simulated vegetation spectra, this study aims at demonstrating that hyperspectral images of vegetated areas can be effectively used to evaluate FMC with accuracies not achievable with multispectral data. To this purpose, radiative transfer models PROSPECT and SAILH have been used to simulate canopy reflectance. Vegetation spectra have then been convolved to hyperspectral data basing on the design specifications of a formerly planned ASI-CSA hyperspectral mission (JHM configuration C), similar to those of the forthcoming PRISMA. For comparison against multispectral instruments, measurements from the Operational Land Imager (OLI) have also been simulated. Two retrieval methods have been tested, based on spectral indexes and on partial least squares (PLS) regression. The latter methodology is particularly suited to analyse high-dimensional data. Results confirm that spectral indexes are good predictors of vegetation moisture expressed as EWT, but their performance in evaluating FMC is poor. By using PLS regression on hyperspectral data, a linear model can be built that accurately predicts FMC. No such result is achievable from OLI simulated data.","fire hazard; vegetation moisture; hyperspectral; remote sensing; PROSPECT; SAILH; PRISMA","en","conference paper","European Space Agency (ESA)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:b26081f6-3890-417e-a91d-ff25537977f4","http://resolver.tudelft.nl/uuid:b26081f6-3890-417e-a91d-ff25537977f4","A New Eulerian Model for Turbulent Evaporating Sprays in Recirculating Flows","Wittig, S.; Hallmann, M.; Scheurlen, M.; Schmehl, R.","","1993","A new Eulerian model for the computation of turbulent evaporating sprays in recirculating flows is derived. It comprises droplet heating and evaporation processes by solving separate transport equations for the droplet's temperature and diameter. Full coupling of the droplet and the gaseous phase is achieved by the exchange of source terms due to momentum, heat and mass transfer. The partial differential equations describing the droplet's transport and evaporation in the new method can be solved using the same numerical procedure as for the gas phase equations. The validity of the model is established by comparison with a well known Lagrangian approach and with experimental data. For this purpose calculations of a recirculating droplet charged air flow within a model combustor are presented.","two phase flow; combustor; Eulerian model","en","conference paper","AGARD","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c253bd2c-00e2-40c9-942a-f0a0f0fb6f9d","http://resolver.tudelft.nl/uuid:c253bd2c-00e2-40c9-942a-f0a0f0fb6f9d","High-resolution PIV analysis of compressibility effects in turbulent jets","Ceglia, G.; Violato, D.; Tuinstra, M.; Scarano, F.","","","An investigation on the compressibility effects arising into the near field of turbulent jets operated at high Reynolds number at Mach numbers M=0.3, 0.9 and 1.1 (under-expanded regime) is carried out with two-components planar PIV experiments with high resolution cameras. The arrangement of the PIV system allows for mapping out the flow field with a vector pitch equal to 0.17mm along the streamwise direction. The flow field is characterized by single-point statistics. For the under-expanded jet, the spatial evolution of the flow field within the potential core region is characterized by the presence of shock-cell structures that extend up to 4.5 downstream from the nozzle exit. Two-point cross-correlation technique is used to investigate the large scale coherent structures in the potential core and in the shear layer. The distribution of the longitudinal spatial correlations valuated in the potential core region of the jet exhibits a phase shifted pattern in sign that extends periodically along the jet axis. This spatial phase shift is approximately 0.5 for M=0.3 and 0.25 for M=1.1. Downstream from =2 and =0, the intensity of the peaks of the spatial correlations in the underexpanded jet is higher than that calculated at Mach 0.3 jet because of the presence of the shock-cell structures in the potential core.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:e301352a-81fb-4307-b95d-2c86c6caf28d","http://resolver.tudelft.nl/uuid:e301352a-81fb-4307-b95d-2c86c6caf28d","Simulating tidal turbines with mesh optimisation and RANS turbulence models","Abolghasemi, A.; Piggott, M.D.; Spinneken, J.; Vire, A.; Cotter, C.J.","","2015","A versatile numerical model for the simulation of flow past horizontal axis tidal turbines has been developed. Currently most large-scale marine models employed to study marine energy use the shallow water equations and therefore can fail to account for important turbulent physics. The model presented here is based on actuator disc momentum (ADM) theory, uses a RANS model to account for turbulence and utilises mesh optimisation in order to address the multi-scale nature of the problem. Furthermore, a series of laboratory experiments were carried out in the hydrodynamics laboratory of the Civil and Environmental Engineering Department at Imperial College London which were used to help validate the numerical model. Turbulence correction terms have been used to capture the short circuiting of the turbulence cascade due to the presence of the disc and thereby improve the match with the experimental data. This model has been developed with the aim that it will be seamlessly combined with larger numerical models simulating tidal flows in realistic domains, e.g. the Inner Sound of the Pentland Firth. This is where the adaptive meshing capability is a major advantage as it enables the mesh to be refined only in the locations required, thus making optimal use of limited computational resources.","tidal turbines; actuator disc momentum; array effects; RANS turbulence model; mesh optimisation","en","conference paper","EWTEC","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:e4fcc516-4c9f-40f6-a3d6-0b14442b42a2","http://resolver.tudelft.nl/uuid:e4fcc516-4c9f-40f6-a3d6-0b14442b42a2","Usage of fiber Bragg grating sensors in low earth orbit environment","Park, S.O.; Moon, J.B.; Lee, Y.G.; Kim, C.G.; Bhowmik, S.","","2008","It is widely known that materials exposed to the severe low earth orbit (LEO) environment undergo degradations. For the evaluation of fiber Bragg grating (FBG) sensors in the LEO environment, the reflective spectrum change and the Bragg wavelength shift of FBG sensor were measured during aging cycles simulating the LEO environment. The LEO environment was simulated by high vacuum (~10-5 Torr), ultraviolet (UV) radiation (<200nm wavelength), temperature cycling (-30°C~100°C), and atomic oxygen atmosphere (AO flux of 9.12×1014 atoms/cm2/s and kinetic energy of ~0.04 eV). FBG sensor arrays were embedded into the graphite/epoxy composite material. Through the aging cycles simulated for the LEO environment, the change in the reflective spectrums and the Bragg wavelengths from FBG sensors were investigated.","composites; low earth orbit; fiber Bragg grating","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerospace Materials","","","",""
"uuid:ae146748-5430-4fbe-bc3d-aa6301e36f1e","http://resolver.tudelft.nl/uuid:ae146748-5430-4fbe-bc3d-aa6301e36f1e","Parachute triggering algorithms for re-entry vehicles","Ording, B.E.; Sudars, M.; Brouwer, G.F.","","2010","Most re-entry vehicles utilize a Descent and Landing System (DLS) for a safe descent through the lowest part of the atmosphere. It usually requires deployment in a certain suitable range of flight conditions, which has to be estimated by limited means of navigation. This paper presents a comparison of currently used trigger methods and triggering algorithms which are based on correlation between in-flight measurements and the DLS triggering conditions, where the correlations have been extracted by multiple Monte Carlo campaigns. This approach gives a significant improvement of triggering accuracy over direct measurements for a ballistic re-entry. Also a lateral g-load safety trigger is developed to prevent the angle of attack oscillation escalation. Furthermore a sensor sensitivity analysis is performed for a lifting entry trajectory in order to support an upcoming ESA re-entry mission. The velocity drift appears to be the dominant dispersion by a factor ten for Mach estimation. Finally a case study has been performed to investigate the possibility to reduce the footprint by a dynamic parachute opening window. This could be effective for Mars reentry using a parachute able to deploy beyond Mach 2.5, which would reduce the footprint by up to several tens of kilometers.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Space Systems Engineering","","","",""
"uuid:19f383d1-048f-4fb1-99d8-ce3f85975723","http://resolver.tudelft.nl/uuid:19f383d1-048f-4fb1-99d8-ce3f85975723","Experimental investigation of a supersonic backward facing step flow","Schrijer, F.F.J.; Modenini, D.","","2008","","supersonic flow; transition; infrared thermography","en","conference paper","ESA-ESTEC","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2c3f7792-ed94-47f6-a6af-d1a89bc87837","http://resolver.tudelft.nl/uuid:2c3f7792-ed94-47f6-a6af-d1a89bc87837","Applications for point cloud skeletonizations in forestry and agriculture","Bucksch, A.; Lindenbergh, R.C.; Menenti, M.","","2009","In recent years, both airborne and terrestrial laser scanning developed to a standard technique for acquiring information on terrestrial landscapes. Here forest inventory and orchard management is considered. Inventory and parameterization of individual trees in orchards and forests are of large interest in nowadays society because of the potential of economical maximization of orchard production and the sustainable management of forests. Complex objects like trees require a detailed structural analysis before an analysis of single trees is possible. Skeletonization is such a structural description that enables the extraction of length, diameters, volumes and position of individual branches but also of trees as a whole. In this paper an overview of current possibilities for skeletonization algorithms on trees is given. A new method of skeletonization, especially designed for the analysis of tree data is described and its applicability demonstrated on airborne and terrestrial laser scanning scenarios. The evidence reviewed in this paper leads to conclude that skeletonization is a valuable tool for forest inventory and orchard management. It will be shown that skeletonization offers the possibility of species independent measurement of trees, which make skeletonization a general tool for parameter extraction on trees that empowers also research fields different from orchard management and forest inventory.","skeleton; orchard; point cloud; forestry; laser scanning","en","conference paper","","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:35b679b4-d669-4215-81ce-dc605bcc3094","http://resolver.tudelft.nl/uuid:35b679b4-d669-4215-81ce-dc605bcc3094","Pumping kites wind farm (poster)","Faggiani, P.; Schmehl, R.; Van der Vlugt, R.","","2015","","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:6859960a-cc68-4685-9159-731199b46354","http://resolver.tudelft.nl/uuid:6859960a-cc68-4685-9159-731199b46354","Six Aerospace design projects to learn how to engineer","Kamp, A.","","2013","Tomorrow’s engineers are required to have a good balance of deep working knowledge of engineering sciences and engineering skills. In the Bachelor in Aerospace Engineering at TU Delft, students are educated to master these competences so that they are ready to engineer when they graduate. The mainstream Aerospace Design is built up semester after semester of a design project and an accompanying design course. The main objectives of the design projects are related to contextual learning, learning by doing together, and learning and practicing academic and engineering skills, and being a mental organiser for the students. Over the years of study the design projects increase in complexity and openness, from knowing to application and synthesis, from tangible to abstract, from mono- to multidisciplinary, and from mostly individual to team work. All projects exploit the factors that promote intrinsic motivation (challenge, curiosity, control, fantasy, competition, cooperation, and recognition). To assure that the intrinsic motivation factors and the semester themes are well addressed, each design project is characterised by a storyline, professional role, client, real-life problem, engineering process, and certain attainment levels of engineering skills.","project-based learning; experiential learning; intrinsic motivation","en","conference paper","","","","","","","","","Aerospace Engineering","Support Aerospace Engineering","","","",""
"uuid:773cdcc9-f82e-47ff-a4d1-e7efb111047e","http://resolver.tudelft.nl/uuid:773cdcc9-f82e-47ff-a4d1-e7efb111047e","Environmental degradation of adhesively-bonded composite joints","Li, C.; Rans, C.D.; LaPlante, G.; Marsden, C.","","2015","","adhesive bonding; fracture; composites","en","conference paper","University of Alberta","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:4462002b-85d1-4689-bd9f-78a6cf475961","http://resolver.tudelft.nl/uuid:4462002b-85d1-4689-bd9f-78a6cf475961","Vibration measurement of a model wind turbine using high speed photogrammetry","Kalpoe, D.; Khoshelham, K.; Gorte, B.","","2011","We investigate the application of the photogrammetric approach to measuring the vibration of a model wind turbine in a sequence of stereo image pairs acquired by high speed cameras. The challenge of the photogrammetric measurement of a highly dynamic phenomenon is the efficiency of the point measurement process in a large number of images. We present a method for automated detection, tracking and measurement of photogrammetric targets in the sequence of stereo images. The tracking process exploits the knowledge of the circular motion of the rotor blades, and thus of the targets, to reduce the space of search for correspondences. The vibration is derived as the deviation of the 3D reconstructed targets from the plane defined by the first two principal components of the target positions in a complete revolution. Our experimental results show the robustness and accuracy of the proposed method for vibration measurement in a highspeed image sequence.","aeroelasticity, automation, target detection, tracking, vibration, video, segmentation","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:255d5f8a-520f-41b1-9bd7-d55fed8a5fad","http://resolver.tudelft.nl/uuid:255d5f8a-520f-41b1-9bd7-d55fed8a5fad","An Avionics Touch Screen based Control Display Concept","Mertens, M.; Damveld, H.J.; Borst, C.","","2012","In many cockpits, control display units (CDUs) are vital input and information devices. In order to improve the usability of these devices, Barco, in cooperation with TU-Delft, created a touch screen control unit (TSCU), consisting of a high-quality multi-touch screen. The unit fits in the standard dimensions of a conventional CDU and is thus suitable for both retrofit and new installations. The TSCU offers two major advantages. First, the interface can be reconfigured to enable consecutive execution of several tasks on the same display area, allowing for a more efficient usage of the limited display real-estate as well as a potential reduction of cost. Secondly, advanced graphical interface design, in combination with multi-touch gestures, can improve human-machine interaction. To demonstrate the capabilities of this concept, a graphical software application was developed to perform the same operations as a conventional CDU, but now using a direct manipulation interface (DMI) of the displayed graphics. The TSCU can still be used in a legacy CDU mode, displaying a virtual keyboard operated with the touch interface. In addition, the TSCU could be used for a variety of other cockpit functions. The paper concludes with a report of pilot and non-pilot feedback.","touch screen, navigation, direct manipulation, gestures","en","conference paper","SPIE (International Society for Optical Engineering)","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:c380073c-3864-433d-acbc-821e8d8c9a04","http://resolver.tudelft.nl/uuid:c380073c-3864-433d-acbc-821e8d8c9a04","Database of measurements on the offshore wind farm Egmond aan Zee","Brand, A.J.; Wagenaar, J.W.; Eecen, P.J.; Holtslag, M.C.","","2012","This paper presents the database of the measurements that have been acquired over the years in the Offshore Wind farm Egmond aan Zee (OWEZ). In addition, two topics are discussed: the analyses on this database that were performed in the past, and the potential for new analyses in the framework of the EU/FP7 project MaRINET. The OWEZ database and the analyses performed on it offer a unique opportunity to study the external conditions of an offshore wind energy site.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:f57d4dd7-fbdd-43d5-aa82-c1abd2a9cc14","http://resolver.tudelft.nl/uuid:f57d4dd7-fbdd-43d5-aa82-c1abd2a9cc14","A meshless front tracking method for the Euler equations of fluid dynamics","Witteveen, J.A.S.","","2009","A second order front tracking method is developed for solving the Euler equations of inviscid fluid dynamics numerically. Front tracking methods are usually limited to first order accuracy, since they are based on a piecewise constant approximation of the solution. Here the second order convergence is achieved by building a piecewise linear reconstruction of the piecewise constant front tracking solution in a post-processing step. The linearization is performed by decomposing the piecewise constant solution of the hyperbolic system into its wave components and by linearizing the wave solutions separately. In order to achieve a physically correct linearization, the front types of the previously developed improved front tracking method are employed. It is illustrated numerically for the one-dimensional unsteady interacting blast waves problem and a two-dimensional supersonic airfoil flow validation study that the proposed front tracking method can achieve second order convergence also in the presents of strong discontinuities.","front tracking; second order; meshless methods; Euler equations","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:e7d6e39f-a238-4c46-bd98-b40b9183b59c","http://resolver.tudelft.nl/uuid:e7d6e39f-a238-4c46-bd98-b40b9183b59c","Investigation of Energy Management during Approach: Evaluating the Total Energy-Based Perspective Flight-Path Display","Van den Hoven, M.C.L.; De Jong, P.M.A.; Borst, C.; Mulder, M.; Van Paassen, M.M.","","2010","This paper covers an analysis of the energy management task during the approach phase as well as the design of an experiment supporting this analysis. The energy management task is analyzed using the concept of energy rate demand, which expresses the amount of total energy to be lost in comparison to the minimal energy rate the aircraft can attain at the current speed and configuration. Energy rate demand is explicitly defined by the altitude and speed profile and indicates the demand put on the aircraft by the approach trajectory. A number of approach trajectories are analyzed including a conventional approach, a Continuous Descent Approach (CDA) and a new, experimental, Constant Energy Rate Demand Approach (CERDA). An experiment has been carried out using a total energy-based perspective flight-path display. The results are used to assess the benefits of adding energy information to a tunnel-in-the-sky display and to gain more insight into the energy management task by comparing the different types of energy management as well as energy rate demand with workload and performance. The hypothesis that adding energy information to a baseline tunnel-in-the-sky display will increase the pilot’s energy awareness is supported, however, the hypothesis that the workload would decrease with the energy display has been rejected. No relation could be found between energy rate demand, workload, and performance, rejecting the hypothesis that the performance would decrease and the workload increase with increasing energy rate demand.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:f0cb9b03-cfea-4602-a07f-1aebdd0a11af","http://resolver.tudelft.nl/uuid:f0cb9b03-cfea-4602-a07f-1aebdd0a11af","The determination of the extreme loads on wind turbines – some practical issues","Bierbooms, W.A.A.M.","","2010","The probabilistic method commonly applied to arrive at the ultimate loading is as follows: for several different mean wind speeds load simulations are performed. For each mean wind speed a conditional distribution can be fitted to the load maxima for that particular wind speed. The overall distribution of the load response is obtained by a weighted average of these conditional distributions taking into account the probability of occurrence of the wind speed bins (Weibull). Two practical issues are addressed: The plotting positions The averaging over the mean wind speeds The plotting positions (for the m-th ranked value out of N) are unique and given by: m/(N +1) . This means that the plotting positions do not depend on the particular application and/or the anticipated distribution function. The maximum of the 50 year estimates based on the exceedance probability Q short (LlUi) is an upper bound of the long term 50 year load value L50. A lower bound for L50 is given by the maximum of the estimates based on the relative exceedance probability Rshort (LlUi)=Qshort (LlUi) ni; with ni the fraction of time for wind speed bin Ui. In the situation that load data of just 1 wind speed bin is available it is in general not possible to determine L50. In case it is assumed that the considered wind speed bin governs the load, a good estimate (lower bound) of L50 is obtained by considering Rshort. If it is assumed that the load distributions of the other wind speed bins are about the same, a good estimate is obtained by considering Qshort (upper bound).","extreme value analysis; extreme external conditions","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:97ebcd9d-ea54-4bc9-b22c-ec3f4a861a68","http://resolver.tudelft.nl/uuid:97ebcd9d-ea54-4bc9-b22c-ec3f4a861a68","Evaluation of Landing Characteristics Achieved by Simulations and Flight Tests on a Small-scaled Model Related to Magnetically Levitated Advanced Take-off and Landing Operations","Rohacs, D.; Voskuijl, M.; Siepenkotter, N.","","2014","The goal of this paper is to simulate and measure on a small-scaled model the landing characteristics related to take-off and landing (TOL) operations supported by a magnetic levitation (MAGLEV) system as ground-based power supply. The technical feasibility and the potential benefits of using ground-based power to assist TOLs is also presented, including the design of the ground-based system, and the envisioned operational concept. The details of the developed control system are given, as well as the (i) simulation and (ii) flight test results.","magnetic levitation; automated landing; landing accuracy","en","conference paper","International Council of Aeronautical Sciences","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:e8038a1c-2dea-43dc-9f13-042f134e1f5f","http://resolver.tudelft.nl/uuid:e8038a1c-2dea-43dc-9f13-042f134e1f5f","Development of an accurate method for advection problems with embedded moving-boundaries","Hassen, Y.; Koren, B.","","2009","An accurate method, using a novel immersed-boundary approach, is presented for numerically solving advection problems. As is standard in immersed-boundary methods, moving bodies are embedded in a fixed, ‘Cartesian,’ finite-volume grid. The essence of the present method is that specific fluxes in the vicinity of a moving body are computed in such a way that they accurately and monotonously accommodate the boundary conditions valid on the moving body. Higher-order accurate discretizations in both space and time are presented. To suppress wiggles, tailor-made limiters are introduced for the special fluxes. The results obtained for linear scalar advection problems are very accurate, without requiring much computational overhead. It is anticipated that the method can be easily extended to real fluid-flow equations","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:28203e4f-7097-4787-bfa3-f57d432971c0","http://resolver.tudelft.nl/uuid:28203e4f-7097-4787-bfa3-f57d432971c0","A quantitative description of the surface healing of ionomers (abstract)","Garcia Espallargas, S.J.; Varley, R.J.; Van der Zwaag, S.","","2011","","ionomers; surface healing; scratch","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:2b33ae14-a7c8-482a-abbc-aba05a77920b","http://resolver.tudelft.nl/uuid:2b33ae14-a7c8-482a-abbc-aba05a77920b","Continuous-time state-space unsteady aerodynamic modelling for efficient aeroelastic load analysis","Werter, N.P.M.; De Breuker, R.; Abdalla, M.M.","","2015","Over the years, wings have become lighter and more flexible, making them more prone to aeroelastic effects. Thus, aeroelasticity in design becomes more important. In order to determine the response of an aircraft to, for example, a gust, an unsteady aerodynamic model is required to determine the dynamic loads. The three most-commonly used methods in aeroelastic loads analysis are 2D unsteady-airfoil theory, the doublet lattice method (DLM), and the unsteady vortex lattice method (UVLM). In contrast to these existing methods, the current paper proposes a 3D state-space model for unsteady aerodynamic analysis that is both directly written in time-domain, and is a continuous-time model. The main advantages of this are that no approximation errors are made in the conversion to the time domain, and that the time step is only driven by requirements on accuracy. The model is based on potential flow theory, which is implemented by means of vortex ring elements. The model was first verified, and then applied to a pitch-plunge response problem showing the benefits of the current approach over existing methods.","unsteady aerodynamics; state-space; loads","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:50d74dc7-5563-4207-a5af-5970b160f2c2","http://resolver.tudelft.nl/uuid:50d74dc7-5563-4207-a5af-5970b160f2c2","Flight Control of the High Altitude Wind Power System","Podgaets, A.R.; Ockels, W.J.","","2007","Closed loop Laddermill flight control problem is considered in this paper. Laddermill is a high altitude kites system for energy production. The kites have been simulated as rigid bodies and the cable as a thin elastic line. Euler angles and cable speed are controls. Flight control is written as a fusion of two approaches: design of experiments and stochastic optimization. Such combination ensures finding global optimum for any reasonable number of parameters and objectives in a reasonable time while also collecting some information about sensitivities – these two features are much harder to achieve by other means. Robustness has been formulated as an additional objective. We found the system very steady despite big variations of wind velocity. The resulting optimal trajectories can be also used as a first iteration for open loop control algorithms.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:cacc778d-8c50-4517-adba-d39912506251","http://resolver.tudelft.nl/uuid:cacc778d-8c50-4517-adba-d39912506251","Flow visualization in the wake of flapping-wing MAV ‘DelFly II’ in forward flight","Percin, M.; Eisma, H.E.; Van Oudheusden, B.W.; Remes, B.; Ruijsink, R.; De Wagter, C.","","2012","Time-resolved velocity field measurements in the wake of the flapping wings of the DelFly II Micro Aerial Vehicle (MAV) in forward flight configuration were obtained by Stereoscopic Particle Image Velocimetry (Stereo-PIV). The PIV measurements were performed at several spanwise planes in the wake of the flapping wings and at a high framing rate to allow a reconstruction of the temporal development of the three dimensional wake structures throughout the flapping cycle. The wake reconstruction was performed by interpolating between the measurement planes through a Kriging interpolation procedure. First, the general wake topology of the DelFly II model is described in conjunction with the behavior of the distinctive flow structures, in particular, tip vortex, trailing edge vortex, and root vortex. Second, the effect of reduced frequency is investigated by changing the flapping frequency. Comparison of the three dimensional wake structures for different cases of reduced frequency reveals major differences in both formation and interaction of vortical structures.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:1e41b7a5-de48-4041-911e-6dfbd5795b5d","http://resolver.tudelft.nl/uuid:1e41b7a5-de48-4041-911e-6dfbd5795b5d","Local sampling for indoor flight","De Croon, G.C.H.E.; De Wagter, C.; Remes, B.D.W.; Ruijsink, H.M.","","2009","A challenging problem in artificial intelligence is to achieve vision-based autonomous indoor flight with Micro Air Vehicles. Approaches to this problem currently do not make use of image appearance features, because these features generally are computationally expensive. In this article, we deliver a proof-ofconcept that appearance features can be extracted computationally efficient enough to be used for autonomous flight. In particular, we present a novel height control algorithm that uses local sampling; it estimates the height at which an image is taken by processing small image patches. We vary the specific number of image patches to directly influence the trade-off between processing time and the accuracy of the height estimation. The algorithm is first tested on image sets and then on videos taken from a real platform. Finally, we test the algorithm on a 15-gram ornithopter in an office room. The experiments show that very few image patches ( 0.56% of all possible patches) are already sufficient for the task of height control.","","en","conference paper","","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:dbdc8820-c401-409f-bd41-fa702bab13d8","http://resolver.tudelft.nl/uuid:dbdc8820-c401-409f-bd41-fa702bab13d8","Functional modelling of airspace","De Neef, R.M.; Van Paassen, M.M.R.","","2001","","functional modelling; air traffic control; airspace; aircraft guidance; conflict detection and resolution","en","conference paper","0rsted DTU, Automation","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2e79c916-8998-42fe-b2b2-9f9010baf6a4","http://resolver.tudelft.nl/uuid:2e79c916-8998-42fe-b2b2-9f9010baf6a4","Preliminary Analysis of a Novel SAR Based Emergency System for Earth Orbit Satellites using Galileo","Gill, E.K.A.; Helderweirt, A.","","2010","This paper presents a preliminary analysis of a novel Search and Rescue (SAR) based emergency system for Low Earth Orbit (LEO) satellites using the Galileo Global Navigation Satellite System (GNSS). It starts with a description of the space user SAR system including a concept description, mission architecture and legal and regulatory aspects. This is followed by a visibility and interference analysis and a high level payload design will be presented.","GPS; satellite navigation","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:89112cd3-cfa2-468e-a030-4d9c50ceba8e","http://resolver.tudelft.nl/uuid:89112cd3-cfa2-468e-a030-4d9c50ceba8e","Skeleton-based botanic tree diameter estimation from dense LiDAR data","Bucksch, A.; Lindenbergh, R.; Mementi, M.; Raman, M.Z.","","2009","New airborne LiDAR (Light Detection and Ranging) measurement systems, like the FLI-MAP 400 System, make it possible to obtain high density data containing far more information about single objects, like trees, than traditional airborne laser systems. Therefore, it becomes feasible to analyze geometric properties of trees on the individual object level. In this paper a new 3-step strategy is presented to calculate the stem diameter of individual natural trees at 1.3m height, the so-called breast height diameter, which is an important parameter for forest inventory and flooding simulations. Currently, breast height diameter estimates are not obtained from direct measurements, but are derived using species dependent allometric constraints. Our strategy involves three independent steps: 1. Delineation of the individual trees as represented by the LiDAR data, 2. Skeletonization of the single trees, and 3. Determination of the breast height diameter computing the distance of a suited subset of LiDAR points to the local skeleton. The use of a recently developed skeletonization algorithm based on graph-reduction is the key to the breast height measurement. A set of four relevant test cases is presented and validated against hand measurements. It is shown that the new 3-step approach automatically derives breast height diameters deviating only 10% from hand measurements in four test cases. The potential of the introduced method in practice is demonstrated on the fully automatic analysis of a LiDAR data set representing a patch of forest consisting of 49 individual trees.","ALS; LiDAR; skeleton extraction; tree delineation; stem diameter estimation; FLI-MAP 400","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Delft Institute of Earth Observation and Space Systems","","","",""
"uuid:fd13c558-af8b-4200-90a6-150d4b1a6926","http://resolver.tudelft.nl/uuid:fd13c558-af8b-4200-90a6-150d4b1a6926","Uncertainty multidisciplinary design optimization of distributed space systems","Guo, J.; Yao, W.; Gill, E.","","2010","The design of Distributed Space Systems (DSSs) is a challenging task, especially in the conceptual design stage where unknown or uncertain information extensively exist. This paper investigates the problem of designing DSSs in the presence of uncertainties. The uncertainties associated with DSSs are discussed. It is shown that DSSs are particularly affected by non-technical uncertainties. Thus, in this paper the methodology of Uncertainty Multidisciplinary Design Optimization (UMDO) is extended to allow inclusion of non-technical uncertainties and is applied to the design of DSS for the first time. The impact of the proposed methodology is investigated through a case study, where the results obtained through UMDO and determinative MDO are compared.","Distributed Space Systems; DSS; Uncertainty Multidisciplinary Design Optimization; UMDO","en","conference paper","International Astronautical Federation","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:105e11ee-c5f9-47b1-beb3-e1836b0f5990","http://resolver.tudelft.nl/uuid:105e11ee-c5f9-47b1-beb3-e1836b0f5990","Application of a knowledge engineering process to support engineering design application development","van der Elst, S.W.G.; van Tooren, M.J.L.","","2008","","knowledge based engineering; DEE; knowledge engineering; agents; wiring harness","en","conference paper","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:21740764-a067-4acd-9da7-e7ab7aea03cb","http://resolver.tudelft.nl/uuid:21740764-a067-4acd-9da7-e7ab7aea03cb","Analysis of tail effects in flapping flight","Tay, W.B.; Bijl, H.; Van Oudheusden, B.W.","","2011","Numerical simulations have been performed to examine the interference effects between an upstream flapping airfoil and a downstream stationary airfoil in a tandem configuration at a Reynolds number of 1000, which is around the regime of small flapping micro aerial vehicles. The objective is to investigate the effect of the distance of the tail and its angle of attack on the overall propulsive efficiency, thrust and lift. An immersed boundary method Navier-Stokes solver is used for the simulation. Results show that efficiency and average thrust can be increased up to 10% and 25% respectively when a stationary airfoil is placed downstream. The simulations reveal how the vortex-shedding pattern of the airfoils are affected by the interaction between them. As the angle of attack of this airfoil increases from 0 to 45o, high lift is generated at the expense of rapidly decreasing efficiency and thrust. The results are not very sensitive to the shape of the airfoil; similar results are obtained with a flat plate airfoil. Lastly, a simple optimization study is performed to obtain the configuration which gave the best performance based on the range of parameters studied. The results obtained from this study can be used to optimize the performance of small flapping MAVs.","Micro Air Vehicle; tail effect; flapping wing","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:15c77161-15fa-4604-ad2e-801645509e06","http://resolver.tudelft.nl/uuid:15c77161-15fa-4604-ad2e-801645509e06","A New Approach for Enhanced Communication to LEO Satellites","Gill, E.K.A.; Verhoeven, C.; Gill, K.; De Milliano, M.","","2010","Operations of satellites in Low-Earth Orbit (LEO) have been based on exploiting the maximum time of visibility of satellites over their ground stations. In this paper, it is shown that a key parameter for communication between a satellite and a ground station is not the time of visibility but the amount of telemetry data which can be transmitted from the satellite to the ground station in the downlink. Given the fact that advanced satellites may allow a variety of data rates for downlink, switching on and off the transponder at higher elevations (i.e. at lower slant ranges) than the minimum possible elevation allows for a higher data rate, and thus, despite of less contact time, for a higher total data volume to be transmitted during a given pass. The paper motivates this new approach for space-ground communication of satellites in LEO on the background of recent technology advances and develops the theoretical framework for enhanced communication. To this extent, an analytical relation is established of the total data volume which can be downlinked for a single pass as a function of the elevation at which the transponder shall be switched on and off. The analysis is limited to a circular LEO and zenith passes. Numerical simulations of the total data volume as a function of this minimum elevation angle are presented as well. Finally, associated opportunities and challenges for enhanced communications are identified and discussed. Conclusions are drawn for future optimized operations of LEO satellites based on given ground segments.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:badf6b35-3d75-4234-8cd2-361f9b62116f","http://resolver.tudelft.nl/uuid:badf6b35-3d75-4234-8cd2-361f9b62116f","Time-Dependent Polynomial Chaos","Gerritsma, M.I.; Vos, P.; Van der Steen, J.B.","","2008","","uncertainty; stochastic ODE; Kraichnan-Orszag problem polynomial chaos; long-term integration","en","conference paper","European Society of Computational Methods in Sciences and Engineering","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ea7d3192-f3fa-4a09-9f01-fb1eaa36c5ab","http://resolver.tudelft.nl/uuid:ea7d3192-f3fa-4a09-9f01-fb1eaa36c5ab","Compartemented fibres: The concept of multiple self-healing in advanced fibre composites","Prajer, M.; Wu, X.; Garcia Espallargas, S.J.; Van der Zwaag, S.","","2013","Polymers reinforced with high performance fibres are successfully replacing metal alloys in lightweight aircraft structures. A critical factor in structural design is the resistance of a structure to progressive damage which develops during its service time. The brittle nature of matrix cracking is the main source of composite failure initiating ply delamination and fibre to matrix debonding. Bio-inspired autonomous healing systems, embedded in a polymer matrix, are being developed to improve the fracture resistance of structural composites [1, 2, 3]. An exemplary system can consist of fibres with individual compartments, i.e. compartmented fibres, which are filled with a healing liquid. The healing agent is distributed within the fibre in the form of long elongated compartments of ellipsoidal shape with high aspect ratio. The fibres are designed to release the liquid healing agent at multiple specific microcrack sites developed in the polymer matrix as a result of structural loading during its life-time. The advantage of such a fibre as a healing agent carrier is obvious - compartmented fibres enable multiple local healing events. Neither is the whole healing agent consumed in the first damage/healing event (as for hollow fibres) nor is the functionality of remaining compartments affected by the healing event (compared to vascular networks). Compartmented fibres were spun from an oil/water emulsion of a healing agent in an aqueous solution of sodium alginate. The retention of the liquid healing agent (orthodichlorobenzene) in a solid fibre was provided by the coagulation of the alginate polymer during fibre formation. Spun fibres were embedded in polymethylmethacrylate, pre-cracked in 3 point bending and allowed a certain period of time to self-heal before they were loaded again. Computed micro-tomography was used to visualise damage and healing sites. Test samples with the new fibres located at the likely damage sites were able to recover, (in part) their mechanical properties. The concept of multiple release of healing agent from a compartmented fibre into the surrounding polymer matrix was demonstrated successfully.","self-healing; polymer composites; compartmented fibres; multiple release","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:1a3a1eff-df90-4a3d-a0fc-d12cf1dab70c","http://resolver.tudelft.nl/uuid:1a3a1eff-df90-4a3d-a0fc-d12cf1dab70c","Gendl meets X3DOM: The Declarative Web, all the Way Down","Cooper, D.; Van Dijk, R.E.C.","","2012","Authoring and maintaining 3D content for the Web typically requires working in disjoint environments: one for creating static or dynamic HTML-based website content, and a different one for making 3D content. For website and web application development, language-based frameworks are typically used. For development of 3D content, a visual CAD-style tools are used, with static models exported to a form useful on the web such as X3D. Users have come to expect dynamic web experience, with content customized to their needs and based on simple user interface elements. Conspicuously absent from mainstream use has been a truly unified, declarative authoring environment which can provide for everything from simple web page generation through to detailed 3D geometric models.","Gendl; KBE; X3DOM","en","conference paper","ACM","","","","","","","2013-08-11","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:3e3433c8-e5eb-4a0f-ada1-7c0d693f0020","http://resolver.tudelft.nl/uuid:3e3433c8-e5eb-4a0f-ada1-7c0d693f0020","Dependency of resolvable gravitational spatial resolution on space-borne observation techniques","Visser, P.N.A.M.; Schrama, E.J.O.; Sneeuw, N.; Weigelt, M.","","2009","The so-called Colombo-Nyquist (Colombo, The global mapping of gravity with two satellites, 1984) rule in satellite geodesy has been revisited. This rule predicts that for a gravimetric satellite flying in a (near-)polar circular repeat orbit, the maximum resolvable geopotential spherical harmonic degree (lmax) is equal to half the number of orbital revolutions (nr) the satellite completes in one repeat period. This rule has been tested for different observation types, including geoid values at sea level along the satellite ground track, orbit perturbations (radial,along-track, cross-track), low-low satellite-to-satellite tracking, and satellite gravity gradiometry observations (all three diagonal components). Results show that the Colombo–Nyquist must be reformulated. Simulations indicate that the maximum resolvable degree is in fact equal to knr + 1, where k can be equal to 1, 2, or even 3 depending on the combination of observation types. However, the original rule is correct to some extent, considering that the quality of recovered gravity field models is homogeneous as a function of geographical longitude as long as l max < nr/2.","","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:b21b8f4a-ef55-459f-8237-c37900247e83","http://resolver.tudelft.nl/uuid:b21b8f4a-ef55-459f-8237-c37900247e83","Workshop designing engineering education the engineering way","Saunders-Smits, G.N.","","2015","","","en","conference paper","Danish Network for Engineering Education (IUPN)","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:634a3ec3-98b8-4863-b987-31447cf99d8f","http://resolver.tudelft.nl/uuid:634a3ec3-98b8-4863-b987-31447cf99d8f","LiDAR for accurate wind resource assessment (poster)","Giyanani, A.H.; Bierbooms, W.A.A.M.; Van Bussel, G.J.W.","","2014","","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:8792b881-3b04-421d-b413-74d4cd3b362f","http://resolver.tudelft.nl/uuid:8792b881-3b04-421d-b413-74d4cd3b362f","A super-resolution approach for uncertainty estimation of PIV measurements","Sciacchitano, A.; Wieneke, B.; Scarano, F.","","2012","A super-resolution approach is proposed for the a posteriori uncertainty estimation of PIV measurements. The measured velocity field is employed to determine the displacement of individual particle images. A disparity set is built from the residual distance between paired particle images of successive recordings. Within each interrogation window, the disparity set is treated with a statistical analysis to infer the measurement uncertainty: the mean disparity is ascribed to bias errors due to poor particle image sampling or spatial modulation effect; the dispersion of the set is related to precision errors, mainly due to random noise in the recordings and to errors in the PIV interrogation. The performance of the estimator is first assessed via Monte Carlo simulation on a uniform flow field with varying out-of-plane displacement. The uncertainty is accurately estimated in optimal imaging condition, while it is underestimated when the imaging conditions are suboptimal. The experimental assessment is conducted on a water jet experiment. For evaluating the performance of the estimator, the actual measurement error is computed as the difference between measured and a reference displacement field; the latter is built with an advanced processing algorithm that exploits the time redundancy of highly oversampled data to reduce the error of one order of magnitude. The capability of the super-resolution technique to quantify the uncertainty within 0.1 px accuracy is proven.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:9e935a86-2279-4699-919e-cadd37704090","http://resolver.tudelft.nl/uuid:9e935a86-2279-4699-919e-cadd37704090","How good are remote sensors at measuring extreme winds?","Sathe, A.R.; Courtney, M.; Mann, J.; Wagner, R.","","2011","This article describes some preliminary efforts within the SafeWind project, aimed to identify the possible added value of using wind lidars to detect extreme wind events. Exceptionally good performance is now regularly reported in the measurement of the mean wind speed with some wind lidars in flat terrain. For turbulence measurements, recent theoretical work has revealed that the components of the Reynolds stress tensor are subjected to significant spatial attenuation and contamination by the cross-components of the horizontal and vertical wind speed. Thus, with the conical scanning of the lidar and velocity azimuth display technique of processing data, precision turbulence measurements are not possible. But how faithfully do wind lidars measure extreme wind events? Our study uses mast and wind lidar data from a flat terrain site. The ZephIR is used as a continuous wave lidar and the WindCube as a pulsed lidar. The data analysis consists of cup-lidar comparisons of the mean wind speed, the maximum wind speed, probability distributions of the time difference of the maximum wind speed, and variation of the gust factors with mean wind speed and atmospheric stability. We examine to what degree each of the different instruments are able to detect extreme events, and attempt to identify the differences in the measurements of the extreme events between cups and lidars. The data analysis showed that both lidars are capable of measuring the maximum wind speed within a 10-min period up to an underestimation of about 10% with respect to the cup anemometer. The Windcube is capable of measuring the gust factor that is comparable to that of the cup anemometer, whereas the ZephIR always underestimates it. The conclusion is still speculative and more theoretical work is required to deduce firm conclusions.","","en","conference paper","","","","","","","","","Aerospace Engineering","Wind Energy","","","",""
"uuid:e489128e-2bb5-47e5-ad8c-e110f471d27b","http://resolver.tudelft.nl/uuid:e489128e-2bb5-47e5-ad8c-e110f471d27b","Representation and Reconstruction of Triangular Irregular Networks with Vertical Walls","Gorte, B.G.H.; Lesparre, J.","","2012","Point clouds obtained by aerial laser scanning are a convenient input source for high resolution 2.5d elevation models, such as the Dutch AHN-2. More challenging is the fully automatic reconstruction of 3d city models. An actual demand for a combined 2.5d terrain and 3d city model for an urban hydrology application led to the design of an extension to the well-known Delaunay triangulated irregular networks (TINs) as to accommodate vertical walls. In addition we introduce methods to generate and refine models adhering to our data structure. These are based on combining two approaches: a representation of the TIN using stars of vertices and triangles, together with segmenting the TIN on the basis of coplanarity of adjacent triangles. The approach is supposed to deliver the complete model including walls at the correct locations, without relying on additional map data, as these often lack completeness, actuality and accuracy, and moreover most of the time do not account for parts facades not going down to street level. However, automatic detection of height discontinuities to obtain the exact location of the walls is currently still under implementation","TIN; Point cloud; reconstruction; 3d data representation","en","conference paper","International Society of Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:da6f9bb6-5306-4b73-af68-efe4e00fe01b","http://resolver.tudelft.nl/uuid:da6f9bb6-5306-4b73-af68-efe4e00fe01b","Future airport turnaround ground handling processes: How to reduce the turn around time of aircraft at the airport","Beelaerts van Blokland, W.W.A.; Huijzer, R.; Stahls, R.; Santema, S.A.","","2008","","","en","conference paper","TRAIL Research school","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3728ea26-c681-4ff5-bcb8-364edd2d1bae","http://resolver.tudelft.nl/uuid:3728ea26-c681-4ff5-bcb8-364edd2d1bae","Bending Test of a Variable-Stiffness Fiber-Reinforced Composite Cylinder","Blom, A.W.; Rassaian, M.; Stickler, P.B.; Gürdal, Z.","","2010","Two carbon-fiber-reinforced composite cylinders were tested in bending. One cylinder, the baseline cylinder, consisted of 0º, 90º and ±45º plies, whereas the other cylinder, called the variable-stiffness cylinder, contained plies with fiber orientations that varied in the circumferential direction, which caused a variation in laminate stiffness. The cylinders were optimized for maximum buckling load carrying capability under bending. Simulations showed that the variable-stiffness cylinder was able to redistribute the applied loads around the circumference, resulting in lower strain values at both the tension and the compression side of the cylinder and an improvement of the buckling load by 18 percent compared to the baseline cylinder. The purpose of the bending test was to show that the improvements obtained in the analytical results could also be achieved experimentally. The baseline cylinder was tested first to serve as a benchmark for the variable-stiffness cylinder. The finite element model was adjusted based on the baseline cylinder tests to represent the experimental conditions correctly. The model took into account the flexible connection between the cylinder and the test fixture, the test mechanism and geometric imperfections present in the cylinder and showed good agreement with the experimental results. The variable-stiffness cylinder was tested twice: first oriented in the direction it was designed for and later rotated 180 degrees about the cylinder axis, such that the loading direction on the cylinder was reversed. The predicted global response and strain distributions for both configurations corresponded well with the experimental data. The flexible boundary conditions and the geometric imperfections affected the load and strain distributions of the baseline and the variable-stiffness cylinders, but the relative improvements of the variablestiffness cylinder in the preferred orientation with respect to the baseline cylinder were not affected. Follow-up tests of the cylinders including cutouts or induced damage are planned in the future.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:4c6772f7-ee7c-4e83-ab0f-bd4bba99fd8f","http://resolver.tudelft.nl/uuid:4c6772f7-ee7c-4e83-ab0f-bd4bba99fd8f","A New Hybrid Method to Correct for Wind Tunnel Wall- and Support Interference On-line","Horsten, B.J.C.; Veldhuis, L.L.M.","","2009","Because support interference corrections are not properly understood, engineers mostly rely on expensive dummy measurements or CFD calculations. This paper presents a method based on uncorrected wind tunnel measurements and fast calculation techniques (it is a hybrid method) to calculate wall interference, support interference and residual interference (when e.g. a support member closely approaches the wind tunnel walls) for any type of wind tunnel and support configuration. The method provides with a simple formula for the calculation of the interference gradient. This gradient is based on the uncorrected measurements and a successive calculation of the slopes of the interference-free aerodynamic coefficients. For the latter purpose a new vortex-lattice routine is developed that corrects the slopes for viscous effects. A test case of a measurement on a wing proves the value of this hybrid method as trends and orders of magnitudes of the interference are correctly determined.","hybrid method; support interference; wall interference; wind tunnel corrections","en","conference paper","World Academy of Science, Engineering and Technology","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:5e25dcd3-0e23-448b-a606-cc5f7373a023","http://resolver.tudelft.nl/uuid:5e25dcd3-0e23-448b-a606-cc5f7373a023","Decay of the turbulent wake from the supersonic micro-ramp","Sun, Z.; Van Oudheusden, B.W.; Schrijer, F.F.J.; Scarano, F.","","2013","The wake resulting from two micro ramps operating in a supersonic boundary layer at Ma = 2:0 is investigated by means of PIV. Two micro ramps are investigated with height of 60% and 80% of the undisturbed boundary layer with thickness of 5.2 mm. The measurement domain encompasses the range from 10 to 32 ramp heights downstream of the device. The decay properties are evaluated in terms of time-averaged and root-mean-square (RMS) statistics. In the time-averaged flow field, the recovery of the imparted momentum deficit and the decay of upwash motion are revealed. The RMS fluctuations of the velocity components exhibit strong anisotropy at upstream locations but develop into a more isotropic regime downstream. The Kelvin-Helmholtz (K-H) instability at the upper shear layer further develops with the onset of vortex pairing. The wavelength evolution is estimated using statistic-based spatial auto-correlation. A marked transition with the wavelength nearly doubled is observed across the pairing regime.","","en","conference paper","PPrime","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:75af0464-8429-405b-92ad-6df2f61317d2","http://resolver.tudelft.nl/uuid:75af0464-8429-405b-92ad-6df2f61317d2","Industrial internships as integrated learning experiences with rich learning outcomes and spin-offs","Kamp, A.; Verdegaal, F.","","2015","At graduation engineering students should be able to use the engineering skills they learnt in advanced industrial applications with preferably little additional training. Authentic design and innovative engineering problems and questions in the life of an engineer should therefore be identifiable subjects in engineering curricula. An important contribution to the attainment of these targets can be obtained by a compulsory internship in the Master programme. Internships can be transformed from a period of work off campus into effective integrated learning experiences with rich learning outcomes. Many of the outcomes relate to key capabilities that eachengineering student should have at graduation, to be prepared for the world of work and create the best chances for a successful career, such as employability, organisational sensitivity, intercultural communication, ethical accountability, professional responsibility and lifelong learning. This paper describes how TU Delft Faculty of Aerospace Engineering has implemented the internship in its programme, including its assignments and assessments with feedback from and to the students, with the aim to have real impact on student development. It describes how company feedback is provided to the students and how this is also fed into the education quality assurance cycle, and in what respect the internship can stimulate the collaboration with industry to achieve a win-win situation. An excellent and professional organisation is a critical success factor. The logistic challenge to coordinate the planning, organisation and assessment of more than 300 - 400 Master students per year, who take an internship all over the globe, is big and demanding. Securing a sound account management with the more than 600 industrial companies, who provide the opportunities for our engineering students, is a condition to achieve sustainable internship opportunities of high quality.","","en","conference paper","CDIO","","","","","","","","Aerospace Engineering","Support Aerospace Engineering","","","",""
"uuid:7cb7aac9-0921-4e12-948f-0ae64aa4bd02","http://resolver.tudelft.nl/uuid:7cb7aac9-0921-4e12-948f-0ae64aa4bd02","Continuous Descent Approaches with Variable Flight-Path Angles under Time Constraints","Sopjes, R.; De Jong, P.M.A.; Borst, C.; Van Paassen, M.M.; Mulder, M.","","2011","In order to reduce noise nuisance around Schiphol Airport, a Continuous Descent Approach procedure was introduced in the late ’90s. Unfortunately, because unpredictable individual aircraft behavior lead to increased landing intervals for this procedure, it is currently only applied during night time operations. Time-of-Arrival control in the terminal area could reduce the landing interval for this procedure. The research presented in this paper investigates the influence of multiple segments with different flight-path angles on the time of arrival. A new procedure with Variable Flight-path angle (VFA) involving active planning of the approach from the pilot through a pilot support interface, presented in the Vertical Situation Display. A preliminary pilot-in-the-loop evaluation was conducted, to investigate pilot performance, workload and interface usability. Three scenarios were tested, all with different Required Time of Arrival. Workload was low for all scenarios and performance good for the two scenarios with early arrival times. For the scenario with a late arrival time, performance was mediocre. Changes in representation of the flap and gear cues and the addition of Estimated Time of Arrival information might improve the performance.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:30be8171-2be9-49f9-a048-b2862c878388","http://resolver.tudelft.nl/uuid:30be8171-2be9-49f9-a048-b2862c878388","An Ecological Approach to the Supervisory Control of UAV Swarms","Fuchs, C.; Borst, C.; De Croon, G.C.H.E.; Van Paassen, M.M.; Mulder, M.","","2014","This research employs ecological interface design to improve the human machine interface of an existing ground control station for the supervisory control of UAV swarms. As a case study, a general ground surveillance mission with four UAVs is envisioned. An analysis of the swarming work domain is performed to generate a reduced set of means-end relations. This analysis leads to a novel design that shows predicted coverage and range of the UAVs in the swarm. An evaluation study with 10 participants showed that the new interface successfully enables operators to control a swarm of four UAVs and mitigate problems during mission execution. The results of the evaluation study showed that operators had a better system understanding and that it promoted creative problem solving activities to scenarios that could not be solved by fixed procedures.","IMAV2014; MAV; Micro Air Vehicle; UAV swarms","en","conference paper","Delft University of Technology","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:2b6a72b7-f6fe-49a8-8a66-a6317240f8e2","http://resolver.tudelft.nl/uuid:2b6a72b7-f6fe-49a8-8a66-a6317240f8e2","Performance Aspects of Orbit Propagation using the Unified State Model","Vittaldev, V.; Mooij, E.; Naeije, M.C.","","2010","The Unified State Model is a method for expressing orbits using a set of seven elements. The elements consist of a quaternion and three parameters based on the velocity hodograph. The equations of this model and the background theory necessary to understand them have been shown here. Numerical simulations comparing the Unified State Model with the traditional Cartesian coordinates have been carried out for perturbed orbits, orbits with low-thrust propulsion, and a solar sailing trajectory. The Unified State Model outperforms Cartesian coordinates for all cases in terms of accuracy and computational speed, except for highly eccentric perturbed orbits. The performance of the Unified State Model is exceptionally better for the case of orbits with continuous low-thrust propulsion with CPU simulation time being an order of magnitude lower than for the simulation using Cartesian coordinates. This makes the Unified State Model especially suited for use in trajectory simulators and optimizers.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:4b5f6cde-d4cb-40a2-bcdb-72460c1738f1","http://resolver.tudelft.nl/uuid:4b5f6cde-d4cb-40a2-bcdb-72460c1738f1","Incorporating Multidisciplinary Design Optimization into Spacecraft Systems Engineering","Guo, J.","","2010","Systems Engineering (SE) and Multidisciplinary Design Optimization (MDO) are usually regarded as two different aspects of spacecraft design. This paper investigates the problem of merging these two fields for the improvement of the spacecraft system design. The SE and MDO processes are described with emphases on their principles, models and tools, followed by a detailed analysis of their relationships and the requirements for merging the two. Promising technologies, such as tradespace exploration and Knowledge-Based Engineering (KBE), are identified as possible connections between SE and MDO. Based on the analysis performed in the paper, a detailed scheme is presented that utilizes these techniques for the incorporation of MDO into spacecraft SE.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:d8e04908-ce4e-4ef6-82c5-87e220272e6f","http://resolver.tudelft.nl/uuid:d8e04908-ce4e-4ef6-82c5-87e220272e6f","On the healing mechanism of sol-gel derived hybrid materials containing dynamic di-sulfide bonds","AbdolahZadeh, M.; Esteves, A.C.C.; Van der Zwaag, S.; Garcia Espallargas, S.J.","","2013","Sol-gel technology is increasingly being used in coatings for corrosion protection and adhesion improvement. So far, the self-healing concept in sol-gel coatings has only been approached from extrinsic healing perspective (i.e. use of nano and micro carriers of corrosion inhibitors) [1]. Despite the benefits of this approach, the damaged area remains open to ambient environment. The implementation of intrinsic healing approaches in sol-gel coatings can thus very well complement current extrinsic ones in order to offer more extended corrosion protection. In the present work the intrinsic healing sol-gel hybrid systems containing dynamic disulfide bonds were developed. The ability of developed systems to restore their cohesion at three different temperatures was evaluated, revealing 70ºC as the optimum healing temperature. In order to get a better understanding of the healing mechanisms, dynamic mechanical thermal analysis (DMTA) was complemented by in-situ raman spectroscopy to follow the evolution of the di-sulfide bonds during the healing cycles. Mechanical properties and content of the broken dynamic bonds were found to be the key parameters in the healing performance of the developed systems. Faster healing kinetics at 70ºC disclosed the dominating role of the breaking/re-joining of the dynamic di-sulfide bonds in the healing mechanism.","sol-gel; self-healing; raman spectroscopy; dynamic mechanical thermal analysis","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:c2187fd6-5185-4ea4-b76a-3b480a69dfea","http://resolver.tudelft.nl/uuid:c2187fd6-5185-4ea4-b76a-3b480a69dfea","Assessment of Innovative Transport Concepts Using Cost Benefits Analyses: The Superbus case","Melkert, J.; Van Wee, B.","","2007","Since the year 2000 the Netherlands are using a new guideline for assessing the costs and benefits of transport systems. This guideline has been used several times now to assess transport systems using existing transport modes like trains. This paper reports on the first time this guideline was used to assess an innovative transport concept, the Superbus, a possible option to connect the North of the Netherlands to the Western urbanized part, the Randstad. The innovative character of the Superbus concept and the fact that it is under development made it difficult to assess this concept. In the assessment the costs of infrastructure, the demand driven logistics and the environmental aspects played an important role. The assessment caused major challenges with respect to the costs of infrastructure, the demand driven logistics and the environmental aspects. From the Cost and Benefit Analysis (CBA) performed it showed that in comparison with the other transport alternatives the Superbus has the lowest costs and the highest benefits. It is concluded that that is has been possible to assess the innovative Superbus concept by using the Dutch guideline for CBA assessments. The most important lessons learnt were the following: - It has been possible to assess the cost of infrastructure based on a combination of a toolbox of infrastructure elements, possible trajectories and adding costs for uncertainties. - Modelling the demand driven logistics has also been possible within the framework of the National Modelling System. - Environmental assessment of the concept has shown to be possible in this early stage of the development as well. - The assessment of the indirect benefits due to the innovative nature of the Superbus has not been possible - A CBA assumes a fully developed system. In case of an innovative system the end of the road towards maturity has not yet been reached. A CBA should be able to take this into account. An approach for this is presented. The authors conclude that in a future assessment of such an innovative concept, the assessment of the potential benefits of innovation, including factors determining success and failure, requires more research since they now have not been taken into account.","","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:d7a36d8b-48d6-4dac-a35c-b4d2aabb381b","http://resolver.tudelft.nl/uuid:d7a36d8b-48d6-4dac-a35c-b4d2aabb381b","Long-Term Laddermill Modeling for Site Selection","Lansdorp, B.; Ruiterkamp, R.; Williams, P.; Ockels, W.J.","","2008","Non-powered flight vehicles such as kites can provide a means of transmitting wind energy from higher altitudes to the ground via tethers. At Delft University of Technology, construction and testing of such a high altitude wind machine is ongoing. The concept is called the Laddermill. It generates energy by pulling a line under high tension from a drum with a kite and retrieving it under low tension. The change in tension is achieved by changing the angle of attack and flight pattern of the kite. This paper presents a modeling and optimization approach that can be used to help design Laddermill systems for particular sites around the world. Some crude assumptions are used to derive the average power that can be produced by a Laddermill system, taking into the most important system parameters. Historical wind data is used to size the kite and cable diameter needed to produce a 1 MW machine for the least cost.","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:feb50bf7-6f4c-4292-aed7-5700e8e4beeb","http://resolver.tudelft.nl/uuid:feb50bf7-6f4c-4292-aed7-5700e8e4beeb","Controllability of blended wing body aircraft","Voskuijl, M.; La Rocca, G.; Dircken, F.","","2008","","","en","conference paper","Optimage Ltd.","","","","","","","","Aerospace Engineering","","","","",""
"uuid:09b1a7f3-e077-4158-9f6e-1b74e9c0636b","http://resolver.tudelft.nl/uuid:09b1a7f3-e077-4158-9f6e-1b74e9c0636b","A highly versatile autonomous underwater vehicle with biomechanical propulsion","Simons, D.G.; Bergers, M.M.C.; Henrion, S.; Hulzenga, J.I.J.; Jutte, R.W.; Pas, W.M.G.; Van Schravendijk, M.; Vercruyssen, T.G.A.; Wilken, A.P.","","2009","An autonomous underwater vehicle with a biomechanical propulsion system is a possible answer to the demand for small, silent sensor platforms in many fields. The design of Galatea, a bio-mimetic AUV, involves four aspects: hydrodynamic shape, the propulsion, the motion control systems and payload. The shape of the hull is based on a modified Wortmann FX 71-L-150/20 airfoil. Wind tunnel tests have been conducted to determine the hydrodynamic force coefficients. The propulsion system is based on bio-mimetic undulating fin propulsion. A test set-up is build to get more insight in the fundamentals of this mechanism. The swimming behaviour is currently manually controlled and will be developed into an fully autonomous system. In the future, more research on the undulating fin propulsion system will be carried out and a second, modular prototype robot will be developed.","biomechanics; hydrodynamics; mobile robots; motion control; remotely operated vehicles; underwater vehicles","en","conference paper","IEEE","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:795f6c19-2304-4592-8a62-f0d33560db89","http://resolver.tudelft.nl/uuid:795f6c19-2304-4592-8a62-f0d33560db89","Time Dependent Flow Simulations using the Least Squares Spectral Element Method with Direct Minimization","Kwakkel, M.; Gerritsma, M.I.","","2006","In this work a new approach to time dependent problems in combination with the Least-Squares Spectral Element Method (LSQSEM) will be discussed. Various timestepping formulations will be presented. These time-stepping formulations will be compared to the full space-time formulation. It will be shown that time-stepping formulations give accurate results for comparable CPU times. Furthermore is will be shown that a smaller timestep or a higher polynomial degree not always decreases the error norm.","least-squares; spectral elements; time-stepping","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:61ca4116-9731-420d-bbf9-516a4a3be313","http://resolver.tudelft.nl/uuid:61ca4116-9731-420d-bbf9-516a4a3be313","Understanding the molecular mechanisms involved in the interfacial self-healing of supramolecular rubbers","Bose, R.K.; Garcia Espallargas, S.J.; Van der Zwaag, S.","","2013","Supramolecular rubbers based on 2-aminoethylimidazolidone and fatty acids with epoxy crosslinks have been shown to self-heal via multiple hydrogen bonding sites. In this work, several tools are used to investigate the molecular mechanisms taking place at the interface to understand cohesive healing in these polymers. The quantification of self-healing was performed via a tapered double cantilever beam (TDCB) geometry. The TDCB geometry is especially amenable to studying multiple healing cycles due to the fracture toughness, and subsequently healing efficiencies being independent of crack length. Healing was carried out for multiple fracturehealing cycles and varying fracture testing experimental parameters to track the change in efficiency of interfacial healing. Strain rate and rate of crack closure are both shown to affect the self-healing efficiency.","supramolecular rubbers; self-healing efficiency; tapered double cantilever beam; rheology","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:8a736606-a00c-4618-9955-1ec44d87471e","http://resolver.tudelft.nl/uuid:8a736606-a00c-4618-9955-1ec44d87471e","Damage resistance of dispersed-ply laminates","Sardar Abadi, P.M.; Jeliazkov, M.; Sebaey, T.A.; Lopes, C.S.; Abdalla, M.M.; Peeters, D.M.J.","","2015","This paper presents the design procedure of a quasi-isotropic (QI) laminate employing dispersion of ply orientations. The goal is to improve damage resistance of a laminate under low velocity impact (LVI). The LVI is treated as a quasi-static loading and instead of a plate a laminated beam is considered. Therefore, this situation simplifies the problem to an interlaminar shear (ILS) test. Although the specimen might experience several failure mechanism, only delamination which influence the load carrying capability of it drastically under compression after impact (CAI) is considered here. By studying the interlaminar shear stresses through the thickness of the laminate, initiation of crack can be inspected in every layer using a quadratic initiation criterion (QIC). Finally, employing a modified ant colony optimization (ACO) algorithm (two-pheromone ACO algorithm) a fully dispersed QI laminate is designed. The domain of the orientation angles is between -85º to 90º with a 5º interval. The results showed that the interface angles does not present a decisive influence on the crack onset. On the other hand, the dispersion tends to have as large as possible angles near the middle of the laminate to minimize the maximum value of QIC, and some small angles in the outside to provide enough bending stiffness.","damage resistance; dispersed-ply laminates; optimization; ant colony algorithm","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:fc7ec49c-aa47-416c-a594-525193707667","http://resolver.tudelft.nl/uuid:fc7ec49c-aa47-416c-a594-525193707667","Prediction and simulator verification of state-space rotor modelling on helicopter manoeuvring flight","Gori, R.; Gennaretti, M.; Pavel, M.D.; Stroosma, O.; Miletovic, I.","","2015","Among the many fundamental components of a flight simulator, the mathematical representation of the vehicle dynamics stands out for complexity and importance. This is especially true for helicopters, for which the complex dynamics involved prevents simple models to be sufficiently accurate without the need of a certain amount of artificial tuning. In this work, a methodology to obtain a computationally efficient, finite-state representation of the aeroelastic response of helicopter main rotors suitable for realtime flight simulation is proposed. It is capable of introducing rotor dynamics effects usually neglected in models commonly applied to flight simulations. This rotor model has been implemented in the SIMONA Research Simulator at the Delft University of Technology, and the results obtained from dedicated flight tests carried out by two experienced pilots are presented and discussed.","","en","conference paper","DGLR and TU Munchen","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:25c716ff-b3e2-42cd-8e30-1fa5ad92ceee","http://resolver.tudelft.nl/uuid:25c716ff-b3e2-42cd-8e30-1fa5ad92ceee","Robust Control of Laddermill Wind Energy System","Podgaets, A.R.; Ockels, W.J.","","2007","Laddermill flight control problem with closed loop is considered in this paper. Laddermill is an alternative concept for energy production using high altitude kites. The kites have been simulated as rigid bodies and the cable as a thin elastic line. Euler angles and cable speed are controls. Flight control is written as a fusion of two approaches: design of experiments and stochastic optimization. Such combination ensures finding global optimum for any reasonable number of parameters and objectives in a reasonable time while also collecting some information about sensitivities – these two features are much harder to achieve by other means. Robustness has been formulated as an additional objective. We found the system very steady despite big variations of wind velocity. The resulting optimal trajectories can be also used as a first iteration for open loop control algorithms. The methods used can be also employed in wide range of wind energy applications.","Laddermill; wind energy system","en","conference paper","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:2f4a2faf-2dc3-42f4-a0e2-da0a988e1ddc","http://resolver.tudelft.nl/uuid:2f4a2faf-2dc3-42f4-a0e2-da0a988e1ddc","Identification of the Feedback Component of the Neuromuscular System in a Pitch Control Task","Damveld, H.J.; Abbink, D.A.; Mulder, M.; Mulder, Mark; Van Paassen, M.M.; Van der Helm, F.C.T.; Hosman, R.J.A.W.","","2010","This goal of this study is to understand which parts of the the neuromuscular system contribute during a pitch control task. A novel method developed at the Delft University of Technology allows us to determine the contribution of the neuromuscular feedback system by identifying the admittance, which is the frequency response function of the yielded displacement due to an external force perturbation which applied to control inceptor. In an experiment in a full-motion flight simulator, the neuromuscular admittance was identified during a longitudinal pitch tracking task with a side stick, for two different side stick configurations, an approach configuration with a relatively low stick stiffness, and a cruise configuration with a high stiffness. Besides the admittance, also the muscle activity of eleven muscles was measured. To validate whether the external force perturbation changed the control behavior of the pilot, the visual and vestibular response functions were identified as well. From the measured results it could be concluded that the variations of the control inceptor settings had a significant effect on the neuromuscular feedback system (admittance), although the overall lumped neuromuscular system did not change significantly. A very interesting finding were the very high levels of co-contraction measured during the pitch tracking tasks. And lastly it could be concluded that the required external force perturbation did not affect the control behavior.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:d71ccc58-bc28-4586-a1b9-89cbfdb90aa9","http://resolver.tudelft.nl/uuid:d71ccc58-bc28-4586-a1b9-89cbfdb90aa9","Thermal cycling fiber metal laminates: Considerations, test setup and results","Müller, B.; Teixeira de Freitas, S.; Sinke, J.","","2015","The development of fiber metal laminates to multi-functional materials by embedding heater elements in the laminate extends their field of application. Fiber metal laminates with embedded heater elements are likely to be used for the de- and anti-icing of leading edges in aircraft as they combine structural and heating functions. Hence, those heated fiber metal laminates are exposed to frequent temperature changes when the de- or anti-icing devices are switched on. In order to examine the possible effects of thermal fatigue loading on the material characteristics, a thermal cycling setup was developed. The experimental setup has the ability to perform thermal cycling tests of materials with and without embedded heater elements. For structural materials, the thermal cycling setup provides external cooling and external heating using Peltier elements. For multi-functional materials (materials with embedded heater elements), the experimental setup enables thermal cycling tests by providing external cooling using Peltier elements and internal heating using the embedded heater mesh. The multi-functional material which is thermal cycled in this study is heated GLARE (Glass Laminate Aluminum Reinforced Epoxy). The temperatures recorded by thermo couples at different specimen positions are presented. The thermal cycle times were about 62 s for temperature cycles from 0°C to 60°C and 2 mm thick heated GLARE specimens. Similar thermal cycling times can be reached for both external cooling and heating and external cooling and internal heating. However, the use of Peltier elements to heat the specimens outer surfaces (external heating) leads to more homogeneous temperature distributions than when using the embedded heater elements as internal heating. The presented experimental setup can be adapted to different specimen dimensions, enables thermal cycling of multiple specimens of the same material, and is applicable for different temperature ranges and heating or cooling rates.","fiber metal laminates; GLARE; thermal cycling; thermal fatigue; moderate temperatures; heater elements; test setup","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:b52a1655-621f-4590-9ad5-0206c090d251","http://resolver.tudelft.nl/uuid:b52a1655-621f-4590-9ad5-0206c090d251","Efficient uncertainty quantification using a two-step approach with chaos collocation","Loeven, A.; Witteveen, J.A.S.; Bijl, H.","","2006","In this paper a Two Step approach with Chaos Collocation for efficient uncertainty quantification in computational fluid-structure interactions is followed. In Step I, a Sensitivity Analysis is used to efficiently narrow the problem down from multiple uncertain parameters to one parameter which has the largest influence on the solution. In Step II, for this most important parameter the Chaos Collocation method is employed to obtain the stochastic response of the solution. The Chaos Collocation method is presented in this paper, since a previous study showed that no efficient method was available for arbitrary probability distributions. The Chaos Collocation method is compared on efficiency with Monte Carlo simulation, the Polynomial Chaos method, and the Stochastic Collocation method. The Chaos Collocation method is non-intrusive and shows exponential convergence with respect to the polynomial order for arbitrary parameter distributions. Finally, the efficiency of the Two Step approach with Chaos Collocation is demonstrated for the linear piston problem with an unsteady boundary condition. A speed-up of a factor of 100 is obtained compared to a full uncertainty analysis for all parameters.","Computational Fluid Dynamics; fluid-structure interaction; non-intrusive; polynomial chaos; stochastic collocation; uncertainty quantification","en","conference paper","Delft University of Technology; European Community on Computational Methods in Applied Sciences (ECCOMAS)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ba549e3d-6b06-4b52-b37c-5d3259ae5d70","http://resolver.tudelft.nl/uuid:ba549e3d-6b06-4b52-b37c-5d3259ae5d70","Immersion and Invariance Based Nonlinear Adaptive Flight Control","Sonneveldt, L.; Van Oort, E.R.; Chu, Q.P.; Mulder, J.A.","","2010","In this paper a theoretical framework for nonlinear adaptive flight control is developed and applied to a simplified, over-actuated nonlinear fighter aircraft model. The framework is based on a modular adaptive backstepping scheme with a new type of nonlinear estimator. The nonlinear estimator is constructed using an invariant manifold based approach which allows for prescribed dynamics to be assigned to the estimation error. Attractivity of the manifold is ensured with the addition of dynamic scaling factors and output filters to the design procedure. The properties of the estimator can be exploited by designing a command filtered backstepping control law that renders the closed-loop system input-to-state stable with respect to the parameter estimation error. It is demonstrated that the resulting modular adaptive controller is easier to tune compared to controllers obtained using the classical adaptive backstepping approaches. Furthermore, the performance of the adaptive controller does not suffer from unpredictable dynamical behavior of the parameter update laws. This is illustrated in numerical simulations where several types of realistic failures are introduced in the aircraft model.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:9df74ade-a631-41a3-9fbe-22f641c187a4","http://resolver.tudelft.nl/uuid:9df74ade-a631-41a3-9fbe-22f641c187a4","Verified Interval Orbit Propagation in Satellite Collision Avoidance","Römgens, B.A.; Mooij, E.; Naeije, M.C.","","2011","Verified interval integration methods enclose a solution set corresponding to interval initial values and parameters, and bound integration and rounding errors. Verified methods suffer from overestimation of the solution, i.e., non-solutions are also included in the solution enclosure. Two verified integration methods, interval Taylor-series and Taylor-model based methods and their implementation in VNODE-LP and VSPODE, are used to reduce overestimation in verified satellite orbit propagation. Furthermore, two orbital state models based on integration constants, the modified equinoctial elements (MEE) and unified state model (USM), are used to reduce overestimation. Earth-satellite trajectories propagated using VSPODE have 2-3 times less overestimation than those propagated using VNODE-LP. Using the USM and MEE state models, overestimation is further reduced by a factor 4 to 10, depending on initial and parameter uncertainties. It is demonstrated that verified collision detection is feasible and may contribute to prevent satellite collisions to reduce future space debris.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:b1824ee4-f604-4d9f-8d21-ac3362740cd5","http://resolver.tudelft.nl/uuid:b1824ee4-f604-4d9f-8d21-ac3362740cd5","Using the Solution Space Diagram in Measuring the Effect of Sector Complexity During Merging Scenarios","Abdul Rahman, S.M.B.; Van Paassen, M.M.; Mulder, M.","","2011","When designing Air Traffic Control (ATC) sectors and procedures, traffic complexity and workload are important issues. For predicting ATC workload, metrics based on the Solution Space Diagram (SSD) have been proposed. This paper studies the effect of sector design on workload and SSD metrics. When considering the SSD in evaluation of a sector, each aircraft within the sector introduces a zone of conflict, the Forbidden Beam Zone (FBZ), on the SSD. The properties of these FBZ are systematically studied to increase understanding of the SSD usability in assessing workload and sector complexity. The effects of sector design variables on Air Traffic Controller (ATCo) workload and also SSD properties were evaluated. Example of sector properties are, number of streams to be merged, the merge angle, the proximity of incoming aircraft and the variability of traffic mix of small and large aircraft. Based on the findings, each sector design variable leads to different effect on both workload and SSD properties. Apart from that, correlation between the workload and the SSD properties were found to be in a higher level than of the number of aircraft within the sector, proving that the SSD-based analysis to be a good workload indicator. These correlations were studied based on two different groups of subjects with ranging experience in order to demonstrate the robustness of the method.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:3d3796aa-3e3e-48a9-b774-9e824d6b9d44","http://resolver.tudelft.nl/uuid:3d3796aa-3e3e-48a9-b774-9e824d6b9d44","Determination of unsteady loads on a DU96W180 airfoil with actuated flap using particle image velocimetry","Lindeboom, R.C.J.; Sterenborg, J.J.H.M.; Simao Ferreira, C.J.","","2010","The unsteady flow conditions experienced by wind turbine blades lead to fatigue loads due to gusts, that increase the cost of energy. The decrease of the impact of these unsteady loads will most certainly lead to a decrease of the cost of energy. In order to alleviate unsteady loads the Smart Rotor Blade approach [2] applies spanwise-distributed smart load control devices, which sense the flow and consequently react on the flow. The smart load control devices are applied to avoid the fluctuating unsteady aerodynamic loads. In the context of alleviating these loads, the unsteady behaviour of the flow over a 2D airfoil due to the actuation of a 0.2 c flap is investigated. By building a database of unsteady flow experiments, reference material is created for the validation of computational fluid dynamics models simulating unsteady conditions. Eventually, the knowledge of unsteadiness of the flow acquired can be applied in projects like the Smart Rotor Blade with the purpose to reduce fluctuating blade loads. An airfoil model of the type DU96W180, with a span of 1.8 meter and a chord of 0.5 meter is tested. Using Particle Image Velocimetry (PIV), the flow is visualized as a function of flap position under unsteady conditions. The unsteadiness addressed is expressed in reduced frequency k, simulating a steady case at k = 0 and unsteady flows at k = 0.1 and k = 0.2. With the integration technique derived by F. Noca [1], the unsteady forces are calculated on the blade, using velocity fields obtained from PIV measurements around the model. Multiple PIV images are stitched together and interpolated on a general grid in order to obtain a velocity vector field of the flow around the model. Having the velocity vector fields at different time steps within one cycle of the flap motion, allows for the determination of a time dependent set of unsteady forces.","Momentum Flux Equation; Particle Image Velocimetry; Smart Rotor Blade; unsteady loads","en","conference paper","European Wind Energy Association","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:6ac989d2-29e0-4ba5-9611-6747c20656eb","http://resolver.tudelft.nl/uuid:6ac989d2-29e0-4ba5-9611-6747c20656eb","Human machine aspects of arrivals management in future air navigation environments","Vormer, F.j.p.; Mulder, M.; Van Paassen, M.M.R.","","2000","","air traffic control; arrivals management; automation; human machine interaction; perspective displays","en","conference paper","European Communities","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f1ec3aee-0994-4c45-9203-05c0dcc5bed1","http://resolver.tudelft.nl/uuid:f1ec3aee-0994-4c45-9203-05c0dcc5bed1","Experimental and numerical investigation of the 3D VAWT wake","Simao Ferreira, C.J.; Hofemann, C.; Van Kuik, G.; Van Bussel, G.","","2009","","","en","conference paper","European Mechanics Society","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:2e8b2001-e909-456f-8254-38bec4cd7b9a","http://resolver.tudelft.nl/uuid:2e8b2001-e909-456f-8254-38bec4cd7b9a","Drag characteristics for optimally span-loaded planar, wingletted, and C-wings","Slingerland, R.; Verstraeten, J.G.","","2008","","","en","conference paper","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7dd05fb2-fa4b-4e75-9477-b5f30bffe4ae","http://resolver.tudelft.nl/uuid:7dd05fb2-fa4b-4e75-9477-b5f30bffe4ae","Post-Buckled Precompressed (PBP) piezoelectric actuators for UAV flight control","Vos, R.; Barrett, R.; Krakers, L.; Van Tooren, M.","","2006","This paper presents the use of a new class of flight control actuators employing Post-Buckled Precompressed (PBP) piezoelectric elements in morphing wing Uninhabited Aerial Vehicles (UAVs). The new actuator relieson axial compression to amplify deflections and control forces simultaneously. Two designs employing morphingwing panels based on PBP actuators were conceived. One design employed PBP actuators in a membrane wingpanel over the aft 60% of the chord to impose roll control on a 720mm span subscale UAV. This design relied ona change in curvature of the actuators to control the camber of the airfoil. Axial compression of the actuatorswas ensured by means of rubber bands and increased end rotation levels with almost a factor of two up to ±13.6?peak-to-peak, with excellent correlation between theory and experiment. Wind tunnel tests quantitatively proved that wing morphing induced roll acceleration levels in excess of 1500 deg/s2. A second design employed PBPactuators in a wing panel with significant thickness, relying on a highly compliant Latex skin to allow for shapedeformation and at the same time induce an axial force on the actuators. Bench tests showed that due to theaxial compression provided by the skin end rotations were increased with more than a factor of two up to ±15.8?peak-to-peak up to a break frequency of 34Hz. Compared to conventional electromechanical servoactuaters, the PBP actuators showed a net reduction in flight control system weight, slop and power consumption for minimal part count. Both morphing wing concepts showed that PBP piezoelectric actuators have significant benefits over conventional actuators and can be successfully applied to induce aircraft control.","piezoelectric; flight control; morphing wing; post-buckled precompressed; UAV","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","System Engineering & Aircraft Design","","","",""
"uuid:704a60a9-e761-4a49-9578-da7dc6f50d96","http://resolver.tudelft.nl/uuid:704a60a9-e761-4a49-9578-da7dc6f50d96","Engineering primitives to reuse design process knowledge","Schut, E.J.; van Tooren, M.J.L.","","2008","","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c4f9ed67-d472-4d3b-b812-ac9457276132","http://resolver.tudelft.nl/uuid:c4f9ed67-d472-4d3b-b812-ac9457276132","Delfi?n3Xt Nanosatellite Subsystems: Buying, Outsourcing or Internal Development","Bouwmeester, J.; Hamann, R.J.","","2009","This paper provides the results of a study of project management and systems engineering effectiveness regarding the allocation of work and procurement policy of a nanosatellite project. The Delfi-n3Xt nanosatellite is currently under development at Delft University of Technology (TU Delft) and will serve as a case study for this analysis. Delfi-n3Xt primary mission objectives are education, technology demonstration (payloads) and advancement of nanosatellite bus subsystems. For each (sub-) system of a satellite, there are in different option to allocate the work or to procure a certain (sub-) system. The criteria for choosing an option can be based on organizational, technical, political and social arguments. A selection of these examples is taken as a case study to provide insight in the rationale behind the choices. It is shown that trade-offs for work allocation or procurement policies are sensitive to different approaches and it is suggested that in many cases trade-offs might be flawed due to subjective manners which have not or will not be documented. It is finally stated that this might lead to problems and it is likely that this lack of transparency also take place in other space projects.","","en","conference paper","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:5aa766ac-ce73-423b-a784-10e9d6f5d300","http://resolver.tudelft.nl/uuid:5aa766ac-ce73-423b-a784-10e9d6f5d300","Unsteady rans simulation of the off-design operation of a high expansion ratio ORC radial turbine","Rinaldi, E.; Pecnik, R.; Colonna di Paliano, P.","","2015","The design of Organic Rankine cycle (ORC) turbines is a challenging task due to the complex thermodynamic behavior of the working fluid, the typical high expansion ratio which leads to a highly supersonic flow, the flow unsteadiness, and the continuous shift of operation between on- and off-design conditions. Computational fluid dynamic (CFD) simulations provide useful insights on the turbine flow which help the design, analysis and optimization process. Steady state CFD computations are nowadays common practice in the design of ORC turbines. However, the inherent unsteadiness of the problem requires time resolved simulations to capture a number of phenomena otherwise ignored, e.g., shock/shock and shock wave/boundary layer interactions, which are expected to dominate the flow evolution. This paper presents a numerical investigation of the off-design operation of a single stage high expansion ratio (>100) ORC radial turbine. Two-dimensional unsteady Reynolds-averaged Navier-Stokes simulations are presented to highlight the main flow characteristics and to study the stator/rotor interaction in terms of time dependent turbine performance parameters and blade loads. An in-house flow solver was used, which accounts for the non-ideal behavior of the fluid via look-up tables generated using a multiparameter equation of state model. The code was previously validated for applications relevant for this study. The analysis shows unique insights on the unsteady flow field in a supersonic ORC turbine and represents the first step toward a new component design approach based on non-stationary flow characteristics.","","en","conference paper","ASME","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:c28362a2-aee8-4ed1-a51d-bcd4124c878e","http://resolver.tudelft.nl/uuid:c28362a2-aee8-4ed1-a51d-bcd4124c878e","An investigation on hybrid interface using on-line monitoring experiment and finite element analyses","Truong, H.T.X.; Martinez, M.J.; Ochoa, O.O.; Lagoudas, D.C.","","2015","In this work, the hybrid interface between metal and thermosetting polymer matrix composite was studied via experimental and numerical investigations. Hybrid laminates, whose constituents are aluminum foil, carbon fabric and epoxy matrix, were manufactured using the vacuum assisted resin transfer molding process. Chromic anodization was used to treat the surfaces of the aluminum foil prior to fabricating the hybrid laminates. The mode-I dominated delamination behavior was studied using the double cantilever beam tests at both room (25oC) and elevated (60oC) temperatures. Distributed strain profiles were measured on both the top and bottom of the specimen using Rayleigh backscattering fiber optics technique. Finite element analysis was performed to assist with the analysis and interpretation of experimental results. Load-displacement and strain profiles measured from experiments were compared with values obtained numerically. Good agreements between the experimental and numerical results were observed.","Double Cantilever Beam (DCB); high temperature; finite elements; fiber optics; hybrid interface","en","conference paper","ICCM","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:0933a111-bb07-41ab-b0a6-728dad9dfecb","http://resolver.tudelft.nl/uuid:0933a111-bb07-41ab-b0a6-728dad9dfecb","Developing a Decision-Support-Tool for an Air Taxi Service in Western Europe","Sengers, P.; Ghijs, S.S.A.","Van Wee, G.P. (contributor); Van Nes, R. (contributor); Van Duin, J.H.R. (contributor)","2008","This paper is a research proposal to develop a tool to analyze logistic concepts of the air taxi service of Aeolus Aviation in different scenarios. Based on this analysis recommendations can be done for a suitable logistic concept for Aeolus. Based on background analysis of the air taxi service three objectives are formulated; analyzing the air taxi service on strategic level, developing a decision support tool to analyze logistic concepts and finally developing a suitable logistic concept for Aeolus Aviation. Based on these objective research questions are formulated and research methods to answer these questions are given.","air taxi; decision support tool; private aircraft","en","conference paper","3rd International Conference on Research in Air Transportation, ICRAT 2008, 1 - 4 June 2008, Fairfax, Virginia, USA","","","","","","","","Aerospace Engineering","Air Transport and Operations","","","",""
"uuid:8243c010-d7c5-47b1-bb47-bf16a7e8fe49","http://resolver.tudelft.nl/uuid:8243c010-d7c5-47b1-bb47-bf16a7e8fe49","Flow over 50º Delta Wings with Different Leading-Edge Radii","Verhaagen, N.G.","","2011","The experimental study focuses on the effects of the leading-edge radius on the flow over 50º swept delta wing models. Three models were tested, one model has a sharp leading edge and two other have a semi-circular leading edge of different radius. The vortical flow on and off the surface of the models was investigated using an oil-flow visualization and a Stereo Particle Image Velocimetry (SPIV) technique. The leading-edge radius is shown to affect the location, size and strength of the vortices and also the vortex core breakdown location over the models. As a result of this, the forces and moment acting on a 50o delta wing are also affected. The study further shows that the structure of the flow over such a wing is weakly dependent on Reynolds number.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3d535d26-55e2-4d06-bce5-2915592ff9c8","http://resolver.tudelft.nl/uuid:3d535d26-55e2-4d06-bce5-2915592ff9c8","Aeroelastic modelling and comparison of advanced active flap control concepts for load reduction on the Upwind 5MW wind turbine","Barlas, A.; van Kuik, G.A.M.","","2009","A newly developed comprehensive aeroelastic model is used to investigate active flap concepts on the Upwind 5MW reference wind turbine. The model is specially designed to facilitate distributed control concepts and advanced controller design. Different concepts of centralized and distributed control schemes based on choices of realistic measurement signals are compared. The sensitivity of important parameters to the load reduction capability is investigated and main differences between control approaches are analyzed. Conclusions are drawn regarding optimal integration of active flaps on wind turbines. Research work is performed at Delft University Wind Energy Research Institute (DUWIND), funded by EU’s FP6 project “UPWIND”.","","en","conference paper","European Wind Energy Association, EWEA","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:6e50cda5-3c14-415e-b800-3e1dd42102b5","http://resolver.tudelft.nl/uuid:6e50cda5-3c14-415e-b800-3e1dd42102b5","Quadrotor system identification using the multivariate multiplex b-spline","Visser, T.; De Visser, C.C.; Van Kampen, E.J.","","2015","A novel method for aircraft system identification is presented that is based on a new multivariate spline type; the multivariate multiplex B-spline. The multivariate multiplex B-spline is a generalization of the recently introduced tensor-simplex B-spline. Multivariate multiplex splines obtain similar or better approximation accuracy using less parameters (B-coefficients) than standard multivariate simplex B-splines which are currently used for aircraft system identification. The multiplex spline allows the user to incorporate a-priori knowledge of the modelled system in the definition of the model structure. In particular, while the standard simplex B-splines use a multi-dimensional triangulation in which all dimensions are coupled, the multiplex spline enables the user to decouple specific model dimensions based on expert knowledge of the system. The new method is used to approximate a 4-dimensional nonlinear quadrotor inflow dataset. The results show that the multiplex B-spline obtains a relative root mean square error of 0.672% using 1440 B-coefficients. This compares favorably to results obtained with the standard 4-dimensional simplex B-spline on the same dataset, which resulted in an relative root mean square error of 1.608% using 1540 B-coefficients.","","en","conference paper","AIAA","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:e3e9d472-d48f-48ac-aef2-76f24517d8e4","http://resolver.tudelft.nl/uuid:e3e9d472-d48f-48ac-aef2-76f24517d8e4","The VAWT in skew: Stereo-PIV and vortex modeling","Simao Ferreira, C.J.; Dixon, K.R.; Hofemann, C.; Van Kuik, G.A.M.; Van Bussel, G.J.W.","","2009","One of the results of the development of wind energy conversion solutions for the built environment is the reappearance of Vertical Axis Wind Turbines (VAWTs). The application of wind turbines in urban environments presents design challenges driven by the complex wind fields experienced in the urban boundary layer. Urban Wind Turbines operate near, on and in the wake of bluff bodies larger than the rotor scale. These flow conditions might result in skewed flow operation. The objective of the current paper is to bring insight into the development of the near wake of a H-VAWT in skewed flow, namely understanding: Blade loading asymmetry in spanwise direction. Trajectory of the tip vortices, including inboard movement and radial expansion of the shed and trailing vorticity. Asymmetry of the wake in spanwise direction. Blade vortex interaction of upwind tip vortex with downwind blade passage. Load distribution in downwind blade passage. Effect of skew in the expansion of the mid-wake. The investigation is composed of experimental wind tunnel research of a two bladed H-Darrieus VAWT model with Particle Image Velocimetry, and modeling of the rotor and wake with a 3D unsteady panel method. Simulations of the rotor in skewed flow are validated with the experimental PIV data and with the torque measurements of 1 and 2 . The results of the panel model, validated by experiments, show the impact of skew angle on the near wake’s development, both for the upwind blade passage as well as the downwind blade passage.","","en","conference paper","American Institute of Aeronautics and Astronautics, AIAA","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:0a311a52-f300-4b0f-aa1d-a756887a09ae","http://resolver.tudelft.nl/uuid:0a311a52-f300-4b0f-aa1d-a756887a09ae","Time-dependent behaviour of the recirculation region behind an axisymmetric bluff-body","Gentile, V.; Schrijer, F.F.J.; Van Oudheusden, B.W.; Scarano, F.","","2015","","","en","conference paper","University of Melbourne","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:af437cf0-8b9b-4247-8b09-effd2418e99e","http://resolver.tudelft.nl/uuid:af437cf0-8b9b-4247-8b09-effd2418e99e","Vacuum testing of a micropropulsion system based on solid propellant cool gas generators","Migliaccio, A.; Zandbergen, B.T.C.; Nardini, F.T.; Louwerse, M.C.","","2010","The number of micro and nano satellite projects is expanding. Main focus is on providing these small satellites with the same capabilities as today's larger satellites. In the field of propulsion, efforts are on miniaturization of the on-board propulsion system. This though presents major challenges to the designers. TNO Defence, Security and Safety, Delft University of Technology and University of Twente have faced those challenges, developing a commercial off-the-shelf cold gas micro-propulsion system, the T3?PS capable of providing a pre-set thrust level in the range 1 to 10 mN. It is based on a highly integrated feeding and thruster system and cool gas generators, which contain nitrogen stored in solid form. The Delfi-n3Xt triple unit cubesat, scheduled for launch in 2011/12, has been chosen as platform to test the capabilities of the T3?PS. To satisfy the Delfi-n3Xt requirements the T3?PS is designed to provide a thrust of maximum 6 mN, minimum impulse bit less than 0.1 mNs and a total impulse of 0.7 Ns. To qualify the T3?PS and verify that it meets the requirements, an extensive test campaign has been devised by TNO. This paper describes the requirements generated, the performance qualification test campaign conducted at Delft University of Technology, the test setup, the used instrumentation and the results obtained. A comparison with theoretical results is also presented.","propulsion; thruster; cool gas; nitrogen; TNO; nozzle","en","conference paper","","","","","","","","","Aerospace Engineering","SpE","","","",""
"uuid:ef521625-a562-49e9-9bde-44538ce159fe","http://resolver.tudelft.nl/uuid:ef521625-a562-49e9-9bde-44538ce159fe","Full Envelope Modular Adaptive Control of a Fighter Aircraft using Orthogonal Least Squares","Van Oort, E.R.; Sonneveldt, L.; Chu, Q.P.; Mulder, J.A.","","2010","A new adaptive nonlinear flight controller is designed for a high fidelity, six degrees of freedom F-16 model for the entire flight envelope. The design is based on a modular approach which separates the design of the control law and the online identifier. The control law design is based on backstepping with nonlinear damping terms to robustify the design against parameter estimation errors and unknown bounded disturbances. The flight envelope is partitioned into hyperboxes, for each hyperbox a locally valid incremental model is estimated based on the linearized equations of motion. A continuous-time formulation of orthogonal least squares is used for identification of these locally valid models. The obtained local models are interpolated by means of B-splines to obtain a smooth model valid for the complete flight envelope. The performance of the resulting nonlinear adaptive control design is evaluated on the F-16 aircraft model for representative flight conditions, maneuvers, and failure cases.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:ba566c70-ccf2-43f1-8c31-484441b59984","http://resolver.tudelft.nl/uuid:ba566c70-ccf2-43f1-8c31-484441b59984","Past, present and future of kites and energy generation","Breukels, J.; Ockels, W.J.","","2007","","wind power","en","conference paper","Acta Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3bc425c0-5001-489e-a5a6-e89a8a39234e","http://resolver.tudelft.nl/uuid:3bc425c0-5001-489e-a5a6-e89a8a39234e","A Time-Space Diagram as Controller Support Tool for Closed Path Continuous Descent Operations","De Leege, A.M.P.; In 't Veld, A.C.; Mulder, M.; Van Paassen, M.M.","","2011","Tactical control during a closed-path Continuous Descent Operation stops the aircraft from following its optimized descent. To mitigate tactical control, air traffic controllers apply arbitrary large spacing buffers to account for the unpredictability of the aircraft trajectory from the controller’s point of view. A controller support tool is required for early de-confliction, spacing, and sequencing to facilitate these operations without the need to apply large buffers. The Time-Space Diagram controller support tool was developed to make the constraints and complexity of a Continuous Descent Operation perceptually evident and provide tools and information to the controller to be an active problem solver. This paper addresses the further development and validation of the interface. The concept of Visual Momentum was applied to enhance the efficiency of working the multi-display interface that consists of the Plan View Display and Time-Space Diagram. Direct Manipulation Interfaces were added to enable the controller to plan and implement actions, such as speed and altitude control. A controller-in-the-experiment was setup to validate the interface. In the experiment the subjects used either the Time-Space Diagram support tool or a stack list that provided the required spacing and time to lose or gain as a baseline. Both interfaces enabled the subjects to space the aircraft safely and efficiently. Compared to the baseline, the Time-Space Diagram interface freed time to plan traffic ahead using the Direct Manipulation Interfaces, which according to all subjects worked intuitively. The number of instructions per aircraft was decreased by 25%. Early accurate speed control was applied and use of heading vectors was no longer necessary in most scenarios. As a result aircraft commenced their continuous descent at a higher altitude and greater distance from the runway. The controller workload was significantly reduced and the level of Situational Awareness increased.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:1c134271-b4a0-40d1-8e8d-1cf3c2f0ee8c","http://resolver.tudelft.nl/uuid:1c134271-b4a0-40d1-8e8d-1cf3c2f0ee8c","New point matching algorithm for panoramic reflectance images","Kang, Z.; Zlatanova, S.","","2007","Much attention is paid to registration of terrestrial point clouds nowadays. Research is carried out towards improved efficiency and automation of the registration process. The most important part of registration is finding correspondence. The panoramic reflectance images are generated according to the angular coordinates and reflectance value of each 3D point of 360° full scans. Since it is similar to a black and white photo, it is possible to implement image matching on this kind of images. Therefore, this paper reports a new corresponding point matching algorithm for panoramic reflectance images. Firstly SIFT (Scale Invariant Feature Transform) method is employed for extracting distinctive invariant features from panoramic images that can be used to perform reliable matching between different views of an object or scene. The correspondences are identified by finding the nearest neighbors of each keypoint form the first image among those in the second image afterwards. The rigid geometric invariance derived from point cloud is used to prune false correspondences. Finally, an iterative process is employed to include more new matches for transformation parameters computation until the computation accuracy reaches predefined accuracy threshold. The approach is tested with panoramic reflectance images (indoor and outdoor scenes) acquired by the laser scanner FARO LS 880.","point matching; panoramic; reflectance image; scale invariant feature transform; Delaunay triangulation; point cloud; registration","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e60968ed-6f3f-4403-9f04-ab9aa38154d1","http://resolver.tudelft.nl/uuid:e60968ed-6f3f-4403-9f04-ab9aa38154d1","Distributed Propulsion featuring Boundary Layer Ingestion Engines for the Blended Wing Body Subsonic Transport","Kok, H.J.M.; Voskuijl, M.; Van Tooren, M.J.L.","","2010","The blended wing body aircraft is one of the promising contenders for the next generation large transport aircraft. This aircraft is particularly suitable for the use of boundary layer ingestion engines. Results published in literature suggest that it might be beneficial to have a large number of these engines (distributed propulsion). A conceptual design study is therefore performed to determine the potential benefits of boundary layer ingestion engines for a conventional number of engines increasing to a large number of engines. A gasturbine performance tool is combined with a weight prediction tool and a mission analysis tool to analyze aircraft-engine combinations. A genetic algorithm is used to find engine specifications that result in minimum fuel consumption for a given configuration (e.g. 8 engines). Results show that the potential of distributed propulsion systems relies heavily on a weak dominance of beneficial effects over negative effects of similar magnitude. From a performance point of view it is better to abandon the distributed propulsion concept and to focus on a small number of large boundary layer ingestion engines instead since they do not suffer high internal losses. A propulsion system with three boundary layer ingestion engines is shown to have a 5% performance improvement in terms of fuel consumption over a conventional strut mounted propulsion system.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:03506a2a-c4af-4d7e-88ad-183ee9c48687","http://resolver.tudelft.nl/uuid:03506a2a-c4af-4d7e-88ad-183ee9c48687","Free flight's big picture concept: Conceptual design of a cockpit human-machine interface in a ground-controlled free flight environment","Passen, M.M.R.; Mulder, M.; De Vriendt, K.","","1999","","free flight; aircraft displays; human-machine interaction; tunnel-in-the-sky","en","conference paper","Group D Publications Ltd","","","","","","","","Aerospace Engineering","","","","",""
"uuid:50ea56ab-f0f5-46f8-a213-3a4957180f4e","http://resolver.tudelft.nl/uuid:50ea56ab-f0f5-46f8-a213-3a4957180f4e","Accelerated partitioned fluid-structure interaction using space-mapping","Scholcz, T.P.; Van Zuijlen, A.H.; Bijl, H.","","2012","The focus of this paper is on acceleration of strong partitioned coupling algorithms for fluid-structure interaction. Strong partitioned coupling requires the solution of a coupled problem at each time step during the simulation. Hereto, an interface residual is defined such that the kinematic and dynamic interface conditions on the fluid-structure interface are satisfied when it amounts to zero. Subsequently, the coupled problem is formulated as a minimization problem of the interface residual which can efficiently be performed using Newton’s method. However, Newton’s method cannot be applied when the fluid and structure solvers are considered black-boxes since the Jacobian of the interface residual is not available. For this reason, Quasi-Newton methods were developed that approximate either the Jacobian or the inverse Jacobian of the interface residual directly from input/output information. In this contribution we present a new algorithm that uses a technique from multifidelity optimization – called space-mapping – to efficiently perform the minimization of the interface residual. The space-mapping technique exploits a computationally inexpensive lowfidelity model in order to accelerate an expensive high-fidelity model using black-box information only. The space-mapping algorithm is applied to the supersonic panel flutter problem in order to demonstrate its effectiveness. The speedup – defined with respect to a Quasi-Newton algorithm – is found to be 1-1.5 for typical time step sizes. It is expected that higher speedups can be obtained when problems are considered that require strong coupling as the time step decreases, e.g. due to the added mass effect when the structure is in interaction with an incompressible fluid.","fluid-structure interaction; partitioned; strongly coupled; space-mapping; quasi-Newton","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:aaee4deb-ae36-4e56-a311-3655c1e10af3","http://resolver.tudelft.nl/uuid:aaee4deb-ae36-4e56-a311-3655c1e10af3","A learning Dempster-Shafer model for automated building detection","Khoshelham, K.; Nardinocchi, C.","Nardinocchi, C. (contributor)","2009","This paper presents a learning Dempster-Shafer model for the detection of buildings in aerial image and range data. The process of evidence assignment in the Dempster-Shafer method is implemented through membership functions in an adaptive network-based fuzzy inference system, where a back propagation learning rule is employed to tune the evidence assignment functions using training samples. The advantage of this method is that it incorporates our knowledge about various features that can be extracted from multi-source aerial data, and the evidence that these features provide for buildings and other objects in urban and suburban areas. Experimental results show that the proposed learning model improves the performance of the Dempster-Shafer classifier in detecting buildings in multi- source aerial data.","building detection; automation; machine learning; classification; fuzzy inference system; neural networks","en","conference paper","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:7f9ca562-07c1-48ce-a361-3b01e95213d0","http://resolver.tudelft.nl/uuid:7f9ca562-07c1-48ce-a361-3b01e95213d0","Dynamic modeling of a spar-type floating offshore wind turbine","Savenije, L.B.; Ashuri, T.; Van Bussel, G.J.W.; Staerdahl, J.W.","","2010","The installation of floating wind farms in deeper water is encouraged by the stronger and steadier wind, the lower visibility and noise impact, the absence of road restrictions, but also the absence or shortage of shallow water. In the summer of 2009, the first large-scale floating wind turbine ”Hywind” was installed. Hywind is a spar-buoy concept with three catenary mooring lines. The experience with modeling floating turbines is still limited. Furthermore, existing models for the design of offshore wind turbines are highly complex as they focus - by definition - mostly on the forces of the wind on the turbine. The correctness and applicability of existing simulation models for the design of floating wind turbines can therefore not be assumed a-priori and need to be researched. This requires that the driving physical processes governing the behaviour of floating wind turbines are investigated first. For this purpose, a new basic model A.T.FLOW has been developed. The requirement of A.T.FLOW is that it incorporates the most significant physical processes so as to be able to provide insight into the dominant physical behaviour of spar-type floating wind turbines. Assumptions have been made that illustrate the limitations of A.T.FLOW. Various verification methods show that the model simulates load cases as expected and is a useful tool for assessing the physical behaviour of spar-type floating wind turbines. The coming two years the body forces and behaviour of the operating full-scale Hywind demo project is monitored. This data should be used to further test and validate A.T.FLOW and to guide further development of the model.","wind; offshore; floating; modeling; hywind; spar","en","conference paper","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:f71b3260-0311-4b06-b4d2-f8c9123d0e53","http://resolver.tudelft.nl/uuid:f71b3260-0311-4b06-b4d2-f8c9123d0e53","On the reduction of NOx emission levels by performing low NOx flights","Mulder, T.J.; Ruijgrok, G.J.J.","","2008","","","en","conference paper","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c40047a0-604e-4364-80d7-dc1d4c47db54","http://resolver.tudelft.nl/uuid:c40047a0-604e-4364-80d7-dc1d4c47db54","Modelling of Waves and Wave-Structure Interactions using Non-Linear Numerical Models","Viré, A.; Spinneken, J.; Piggott, M.D.; Pain, C.C.; Kramer, S.C.","","2014","The aim of this study is to validate a fully non-linear finite-element model to simulate waves and wave-structure interactions. The Navier–Stokes equations are solved on an extended domain, which covers both fluid and structure. The latter is represented by a non-zero solid-concentration field, which is computed by conservatively mapping a mesh discretising the solid onto the extended mesh. In the regions of non-zero solid concentration, a penalty force is further added to the equations of motion in order to represent the effect of the structure on the fluid dynamics. The results are first shown for the interactions between a cylindrical pile and a regular train of small-amplitude gravity waves in a numerical wave tank. The pile is considered both as an immersed body and as a void in the fluid domain. In both cases, good overall agreement is obtained between the numerical and theoretical predictions of the free-surface elevation. The immersedbody approach however tends to underestimate the water elevation in the vicinity of the structure, due to additional dissipation induced by the body force. Second, the generation of focused wave events is considered. Preliminary results suggests that the present model is capable of modelling focused wave events propagating in the numerical wave tank. This is a first step towards modelling the interactions between pile and steep irregular waves.","fluid-structure interactions; immersed-body method; wave modelling; unstructured finite-element methods; offshore piles","en","conference paper","CIMNE","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:5999b633-a188-49e1-abcc-dddbaee301a6","http://resolver.tudelft.nl/uuid:5999b633-a188-49e1-abcc-dddbaee301a6","Gridless Determination of Aerodynamic Loads Using Lagrangian Particle Tracks","Mertens, C. (TU Delft Aerodynamics); Costa Fernandez, J.L. (TU Delft Aerospace Engineering); Sciacchitano, A. (TU Delft Aerodynamics); van Oudheusden, B.W. (TU Delft Aerodynamics); Sodja, J. (TU Delft Aerospace Structures & Computational Mechanics)","","2021","The aerodynamic loads on a flexible wing in terms of the surface pressure distribution and the lift force along the span are determined experimentally based on non-intrusive Lagrangian particle tracking (LPT) measurements. As the flexible wing deforms under the aerodynamic loads, its deformed shape is first reconstructed based on structural LPT measurements conducted together with the flow measurements in an integrated approach. Based on the reconstructed wing shape, flow tracers data are collected along surface normals to evaluate the surface pressure, as well as along elliptic paths around the wing to determine the circulation. The lift force is calculated from the surface pressure by integrating the pressure difference along the chord, as well as from the circulation using the Kutta-Joukowski theorem. The circulation-based lift results
are in very good agreement with reference measurements from a force balance, with differences in the total lift force on the wing of less than 5%. The lift estimation based on the extrapolated surface pressure is consistently lower than the circulation-based lift, by about 10%, due to the limited accuracy of the pressure extrapolation near the leading edge region, where a considerable fraction of the lift is generated.","","en","conference paper","","","","","","","","","Aerospace Engineering","","Aerodynamics","","",""
"uuid:e0f1a8a4-92f2-4093-acfc-d5276752cc9b","http://resolver.tudelft.nl/uuid:e0f1a8a4-92f2-4093-acfc-d5276752cc9b","In-flight deployment of morphing UAVs: A method to analyze dynamic stability, controllability and loads","Voskuijl, M. (TU Delft Flight Performance and Propulsion); Muhammad Ridho Said, Muhammad Ridho (TU Delft Aerospace Engineering); Pandher, Jaspreet (University of South Carolina); van Tooren, Michel (University of South Carolina); Richards, Blin (VX Aerospace)","","2019","Several morphing unmanned aircraft systems which can be deployed in-flight are currently being developed for a variety of missions. Key to a successful in-flight deployment of these aircraft is that they enter a stable and controllable flight phase following a potentially highly dynamic transition phase without exceeding structural limitations. The aim of the current study is to develop a new physics-based methodology which can be used to assess under which flight conditions an unmanned morphing aircraft can be safely deployed in terms of stability, controllability and dynamic flight loads. The method is based on a Monte Carlo Simulation of the deployment phase with a multibody dynamics simulation model. As test case, the Dash X UAV is analyzed in combination with different deployment scenarios. Parameters to be varied are initial flight conditions such as body angular rates and the morphing strategy. The model is validated against a limited set of flight test data in its deployed state. Example results of the aircraft motion and loads are presented for safe deployments with a highly dynamic transition phase. The procedure to construct stability limits and deployment load envelopes is presented. The deployment load envelopes are a natural extension to the V-n diagram typically used for structural design. The stability limits can be used to determine the operational limits under which a UAV can be deployed safely without the risk of entering an unstable or uncontrollable flight regime. Ultimately, this method can be used to support the design of in-flight deployable morphing UAVs and the related operational procedures. It is demonstrated that the Dash X UAV can be safely deployed under realistic conditions with acceptable structural loads.","","en","conference paper","American Institute of Aeronautics and Astronautics Inc. (AIAA)","","","","","","","","Aerospace Engineering","","Flight Performance and Propulsion","","",""
"uuid:b3f21d10-cf4c-4dfb-ba23-034071314e38","http://resolver.tudelft.nl/uuid:b3f21d10-cf4c-4dfb-ba23-034071314e38","Design and Experimental Validation of Swirl Recovery Vanes for Propeller Propulsion Systems","Li, Q. (TU Delft Flight Performance and Propulsion); Öztürk, K. (TU Delft Aerospace Engineering); Ragni, D. (TU Delft Wind Energy); Sinnige, T. (TU Delft Flight Performance and Propulsion); Eitelberg, G. (TU Delft Flight Performance and Propulsion); Veldhuis, L.L.M. (TU Delft Flight Performance and Propulsion); Yangang, Wang (Northwestern Polytechnical University)","","2017","","","en","conference paper","American Institute of Aeronautics and Astronautics Inc. (AIAA)","","","","","","","2018-06-09","Aerospace Engineering","","Flight Performance and Propulsion","","",""
"uuid:b2e5d9e2-9c34-4da9-9b45-c2470dfaa407","http://resolver.tudelft.nl/uuid:b2e5d9e2-9c34-4da9-9b45-c2470dfaa407","Train describer records as a source of information for infrastructure monitoring, performance analysis and traffic management","Kecman, P. (TU Delft Transport and Planning); Goverde, R.M.P. (TU Delft Transport and Planning); Hansen, L.D. (TU Delft Aerospace Engineering)","","2011","Data records from tram describer systems represent a valuable source of information for analysing system performance and assessing railway timetable quality. The aim of this paper is to introduce the Dutch tram describer system and present algorithms developed for automatic identification of track blockages, route conflicts (including the identification of conflicting trains), accurate arrival and departure times/delays at stations, and realized train paths on track section level with the associated blocking times. Analysis of these realisation data can be used to identify incidents and disruptions, as well as to determine structural errors in the timetable design in order to increase the system performance.","route conflicts; timetables; train describers","en","conference paper","","","","","","","","","Aerospace Engineering","","Transport and Planning","","",""
"uuid:71a976fa-eb71-42f0-af1d-ec12c2cc2d44","http://resolver.tudelft.nl/uuid:71a976fa-eb71-42f0-af1d-ec12c2cc2d44","Experimental study of symmetric and asymmetric shock-shock interactions with variable inflow Mach numbers","Santiago Patterson, J. (TU Delft Aerospace Engineering; TU Delft Aerodynamics); Laguarda, L. (TU Delft Aerodynamics); Schrijer, F.F.J. (TU Delft Aerodynamics); van Oudheusden, B.W. (TU Delft Aerodynamics); Hickel, S. (TU Delft Aerodynamics)","","2019","An experimental investigation of shock-shock interactions has been conducted with the aim of studying the transition between Regular (RI) and Mach (MI) interactions induced by a variation of the inflow Mach number. The experiments were conducted in the TST-27 wind tunnel at Delft University of Technology. For all cases, the wind tunnel runs were initialized in the RI domain after which the Mach number was slowly decreased to the MI domain, thereby traversing the whole dual solution domain. The process was then inverted to reach again the RI domain in order to investigate a possible transition hysteresis. Both conventional Schlieren and Focusing Schlieren systems were used to visualize the shock wave patterns. The recorded Schlieren images allow accurate transition detection together with quantitative measurements of the Mach Stem Heigth (MSH). The results show no hysteresis effects. All transitions are recorded to occur at the von Neuman line, for both RI to MI and MI to RI cases.","","en","conference paper","","","","","","","","","Aerospace Engineering","","Aerodynamics","","",""
"uuid:91be8675-5ef9-456e-97a2-f979498e49b0","http://resolver.tudelft.nl/uuid:91be8675-5ef9-456e-97a2-f979498e49b0","Stability of Swept Wing Boundary Layers under Non-Adiabatic Wall Conditions","Barahona Lopez, M. (TU Delft Aerodynamics); van de Weijer, A.F. (TU Delft Aerospace Engineering); Rius Vidales, A.F. (TU Delft Ship Hydromechanics and Structures); Kotsonis, M. (TU Delft Aerodynamics)","","2024","One of the most critical technological challenges embedded in the electrification of future aircraft revolves around the thermal management of batteries and fuel cells. An innovative idea involves using the aircraft’s aerodynamic surfaces to dissipate the extra heat, thereby reducing the impact that traditional thermal management systems (e.g. ram air heat exchanger) have on the overall aerodynamic efficiency of the aircraft. However, the limited experimental research addressing the influence of a heated surface on the stability and transition of the crossflow instability (CFI) hinders the assessment of the aerodynamic impact of this technology for future aircraft, where swept wings are ubiquitous. Thus, the objective of this work is to experimentally study the effect of a heated wall on the stability and final breakdown of CF vortices. To do so, experiments are conducted on a 45◦ swept flat plate wind tunnel model, where the surface temperature is increased by means of a surface-embedded electrical heater, yielding a mean wall-temperature ratio of T_w/T_infty = 1.055. Overall, the experimental (i.e. HWA) and numerical (i.e. CLST) results show that wall heating leads to significant destabilization of the stationary CFI. Interestingly, a spectral analysis of the HWA signal reveals substantial amplification of the traveling CF mode under wall-heating conditions, which in turn appears significantly more destabilized than the stationary CF mode. Additionally, inspection of the high-frequency content in the HWA measurements indicates premature breakdown of the CF vortices and advancement of the laminar-turbulent transition by 6.3% with wall heating. The results presented in this work render a first insight into the impact of a non-adiabatic wall on the development of the crossflow instability and subsequent breakdown to turbulence.","","en","conference paper","American Institute of Aeronautics and Astronautics Inc. (AIAA)","","","","","","","","Aerospace Engineering","","Aerodynamics","","",""
"uuid:63425b71-a307-4295-9ee5-b1b115a3c0b3","http://resolver.tudelft.nl/uuid:63425b71-a307-4295-9ee5-b1b115a3c0b3","Photon-Sail Trajectories Towards Exoplanet Proxima b","Heiligers, M.J. (TU Delft Astrodynamics & Space Missions); Rotmans, T.J. (TU Delft Aerospace Engineering)","","2023","This paper investigates trajectories within the Alpha Centauri system to reach planet Proxima b. These trajectories come in the form of connections between the classical Lagrange points of Alpha-Centauri’s binary system (composed of the stars Alpha Centauri A and B, AC-A and AC-B) and the classical Lagrange points of the Alpha Centauri C (AC-C)/Proxima b system. These so-called heteroclinic connections are sought using a patched restricted three-body problem method. A genetic algorithm is applied to optimize the linkage conditions between the two three-body systems, focusing on minimizing the position, velocity, and time error at linkage. Four different futuristic, graphenebased sail configurations are used for the analyses: two sails with a reflective coating on only one side of the sail with lightness numbers equal to β = 100 and β = 1779, and two sails with a reflective coating on both sides (again, considering β = 100 and β = 1779). Results from the genetic algorithm show that, for example, a transfer from the L2-point in the AC-A/AC-B system to the L1-point in the AC-C/Proxima b system can be accomplished with a transfer time of 235 years for the one-sided graphene-based sail with β = 1779.","","en","conference paper","","","","","","","","","Aerospace Engineering","","Astrodynamics & Space Missions","","",""
"uuid:36d2e6b5-fb48-429a-9fb7-01d18f8b9d30","http://resolver.tudelft.nl/uuid:36d2e6b5-fb48-429a-9fb7-01d18f8b9d30","Uncertainty quantification for solar sails in the near-Earth environment","Garcia Bonilla, J. (TU Delft Aerospace Engineering); Carzana, L. (TU Delft Astrodynamics & Space Missions); Heiligers, M.J. (TU Delft Astrodynamics & Space Missions)","Kezerashvili, Roman (editor)","2023","This paper addresses the significance of uncertainty quantification in solar-sail missions, focusing on the uncertainties associated with the sail’s optical coefficients, structural deformation, and attitude profiles for missions in the Earth environment. Due to the relatively low technological maturity of solar-sailing systems, understanding and quantifying uncertainties is crucial for mission success and reliability. This paper employs the Gauss von Mises method for uncertainty propagation and stochastic integration of Ornstein-Uhlenbeck processes, which proved to be robust methodologies for quantifying and modelling uncertainties. The results show a significant impact of uncertainties in the optical coefficients on mission performance, exemplified by a 3-σ uncertainty of 7.5% on the increase in semi-major axis achieved during orbit raising maneuvers using the coefficient uncertainties of the NEA Scout mission. As another example, the analysis on attitude uncertainty demonstrates a 3% lower mean performance in terms of altitude gain compared to ideal control profiles. The research furthermore underscores the effectiveness of the Gauss von Mises method, offering great computational efficiency compared to Monte Carlo simulations. These findings highlight the necessity of considering uncertainty in solar-sail missions and provide valuable insights for improved mission planning, risk assessment, and decision-making.","","en","conference paper","","","","","","","","","Aerospace Engineering","","Astrodynamics & Space Missions","","",""
"uuid:4d0e894c-d0ad-4983-9fa3-505a8c6869f1","http://resolver.tudelft.nl/uuid:4d0e894c-d0ad-4983-9fa3-505a8c6869f1","Improving BEM-based Aerodynamic Models in Wind Turbine Design Codes","Sant, T.","Van Kuik, G.A.M. (promotor); Van Bussel, G.J.W. (promotor)","2007","","wind turbine; aerodynamics; blade-element momentum theory; vortex theory; angle of attack; aerofoil data","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:46f2e44b-1a68-44f8-9633-79490a54e087","http://resolver.tudelft.nl/uuid:46f2e44b-1a68-44f8-9633-79490a54e087","Structural Performance of Fiber-Placed, Variable-Stiffness Composite Conical and Cylindrical Shells","Blom, A.W.","Gürdal, Z. (promotor)","2010","The use of fiber-reinforced composites in aerospace structures has increased dramatically over the past decades. The high specific strength and stiffness, the tailorability, and the possibilities to integrate parts and reduce the number of fasteners give composites an advantage over metals. Automation of the production process enables large-scale production of composites in a repeatable, reliable fashion. Fiber-reinforced composite laminates are traditionally made of 0?, 90? and ±45? plies. Automated manufacturing techniques, such as advanced fiber placement, allow for fiber orientations other than 0?, 90? and ±45?, and for the placement of curved fibers such that the fiber orientation within a ply is continuously varied. Laminates that contain plies with spatially varying fiber orientations have a spatially varying stiffness and are called variable-stiffness composites. Tailoring the stiffness variation can be used to improve the structural efficiency of a composite. Analytical and experimental work on flat variable-stiffness composite panels with and without central holes has shown that large improvements in structural efficiency are feasible, such as increasing the panel strength or buckling load while maintaining the same overall weight. The research presented in this dissertation expands the work on variable-stiffness composite laminates from flat panels to conical and cylindrical shells. Variable-stiffness plies with either an axial or a circumferential stiffness variation are defined based on the shifted course principle, where a full ply is formed by shifting identical courses in the direction perpendicular to the direction in which the fiber angle is varied. Four different types of fiber paths are discussed: i) geodesic paths, ii) constant angle paths, iii) paths with a linearly varying fiber angle, and iv) paths with a constant curvature. General mathematical descriptions to define the coordinates of these paths on a conical or cylindrical shell and expressions for the in-plane curvature are derived. The in-plane curvature is limited to a maximum value to ensure a good laminate quality, assuming the variable-stiffness laminate is manufactured using advanced fiber placement. A procedure to determine the exact stacking sequence for a given location within a laminate is given. Structural analyses were carried out using the finite element rogram ABAQUS. The stiffness variation was implemented in the finite element shell model as a user-written FORTRAN subroutine, such that each element was uniquely defined. Two design studies were carried out, using the ABAQUS models to evaluate the structural performance of variable-stiffness composite laminates. The first design study was the optimization of conical and cylindrical shells with different dimensions for maximum fundamental frequency. The 8-ply laminates had a [±45±?(x)]s layup, where ?(x) denotes a ply with an axially varying fiber angle, and the laminate thickness was assumed to be constant. Manufacturability of the variable-stiffness plies was judged based on the maximum in-plane path steering allowed by the fiber placement process. Numerical examples showed that manufacturability can have a large influence on the value of the maximum fundamental frequency of conical and cylindrical composite shells with an axial stiffness variation, and that it is necessary to take the manufacturing constraints into account in the design phase of a variable-stiffness laminate. It was shown that the fundamental frequency of conical and cylindrical shells can be improved up to 30 percent by using variable-stiffness laminates, especially for larger cones. The second design study covered the maximization of the buckling load of a variable-stiffness composite cylinder loaded in bending. It was shown that the use of variable-stiffness constant-thickness laminates may improve the buckling load of a cylinder under pure bending because it allows the redistribution of in-plane loads between the compression and tension parts around the circumference by tailoring the circumferential in-plane stiffness distribution in the cylinder skin. The compressive loads were reduced and spread out over a larger part of the cylinder circumference thus increasing the buckling load and changing the buckling mode shape. Loading was also shifted from buckling-critical compression loads into buckling-noncritical tension loads. The redistributed loads caused the first buckling mode to change such that a larger part of the cylinder participated in the buckling deformations. Introduction of curvature, strength and stiffness constraints caused a small reduction in buckling load carrying capability of the variable-stiffness designs. These manufacturable and more practical laminates showed improvements of up to 18 percent compared to the optimized baseline consisting of 0?, 90? and ±45? plies. The buckling load carrying capability of variable-stiffness designs that included overlapping fiber courses was optimized by increasing the laminate thickness on the compression side of the cylinder. The larger laminate thickness, which is coupled to the fiber angle variation, was achieved by having a small fiber orientation on the compression side of the cylinder and a large fiber orientation near the neutral axis. The increased laminate thickness and the small fiber orientation caused high axial stiffness, resulting in high axial loads on the compression side of the cylinder. The laminate bending stiffness on the compression side increased more than the in-plane laminate stiffness, however, such that it compensated for the higher axial loads and dominated the response. Including the curvature and strength constraints had a higher impact on the variable-stiffness designs with overlap than on the ones with a constant thickness. The amount of thickness buildup on the compression side was limited, because the shift of the neutral axis associated with the high axial laminate stiffness on the compression side caused failure on the tension side of the cylinder. The laminate stiffness and thickness on the tension side became similar to those on the compression side. One constant-thickness, variable-stiffness specimen and two baseline specimens were manufactured using advanced fiber placement technology. Both designs were optimized for maximum buckling load carrying capability under bending. The small dimensions of the cylinder required a small turning radius, causing puckers to form during lay-down which were not visible in the end product. The amount of small triangular gaps and overlaps within the constant-thickness laminate was minimized by using a 50 percent coverage parameter, while long gaps between parallel courses were avoided by adjusting the shift between courses. The minimum cut length requirement was taken into account during the design, preventing any deficiencies in placing tows on the surface. Cutting tows on the outside of a steered course caused the tows to straighten, because the outer tows were not restrained and thus followed a geodesic path. Adjustments are needed in future variable-stiffness designs to avoid fiber straightening. A modal test was carried out on the variable-stiffness and on one of the baseline fiber-reinforced composite cylinders that were optimized for bending. An ABAQUS finite element model was used to predict the modal behavior of the cylinders. The analytically predicted mode shapes and modal frequencies showed a good agreement with the experimental results, both for the baseline and for the variable-stiffness cylinder. The modal frequencies of the variable-stiffness cylinder were lower than those of the baseline cylinder due to the lower laminate bending stiffness in the circumferential direction, which plays an important role in the formation of waves in the circumferential direction. The larger axial stiffness of the variable-stiffness cylinder became apparent for modes with an increasing number of axial half waves and the modal frequency of the variable-stiffness cylinder approached or even exceeded the modal frequency of the baseline cylinder. The modal response simulations executed in ABAQUS matched the experimental results both for location and amplitude of the response. Although only 2 cylinders were tested, the presented results indicated that the finite element model for the variable-stiffness cylinder provides a good representation of the cylinder in terms of mass and stiffness distributions. A fixture was designed to test the baseline and the variable-stiffness cylinders in pure bending. Strains and displacements were measured using strain gauges, digital image correlation, LVDT’s and lasers. Three carbon fiber-reinforced cylinders were tested: two with a baseline laminate and one with circumferentially varying laminate stiffness. The variable-stiffness cylinder was tested in two configurations: i) it was tested in the orientation for which it was optimized, called the preferred configuration, and ii) it was tested while rotated 180? about the longitudinal axis, such that the loading on the cylinder was reversed, this was called the reversed configuration. This resulted in three test configurations: the baseline, the variable-stiffness in the preferred orientation and the variable-stiffness in the reversed orientation. A comparison of the experimental response of the two baseline cylinders with the finite element predictions revealed that the experimental boundary conditions were more flexible than originally modeled in the finite element model. The introduction of flexible boundary conditions in the finite element model resulted in good agreement between the experimental and the analytical results. A final improvement of the finite element predictions was achieved by including geometric imperfections in the model and by performing a Riks analysis. The latter model was used to make a prediction for the variable-stiffness test results. A comparison of the experimental results with the finite element predictions of the Riks analysis in general showed a good agreement for all three configurations. The match of the end rotations and strains was equally good for the variable-stiffness cylinder and the baseline cylinder. The variable-stiffness cylinder was stiffer than the baseline cylinder when comparing the global behavior in terms of end rotations, which was to be expected because of the larger laminate stiffness of the variable-stiffness cylinder. The variable-stiffness cylinder response was stiffer in the reversed orientation than in the preferred orientation due to the boundary condition effects. The most important observation resulted from the strain distribution with the vertical coordinate of the cylinder: at equal load level the maximum compressive strains of the variable-stiffness cylinder in the preferred orientation were about 10 percent lower than those of the baseline cylinder; the tensile strains were 35 percent smaller. This difference in extreme strain values is a large improvement in performance when strain-based strength criteria are applied. In addition, the circumferential stiffness variation resulted in a redistribution of the loads, such that the tension side was more effective in carrying loads, the compressive loads were carried by a larger part of the cylinder and the compressive load peak at ? = 180? was reduced by 25 percent compared to the baseline cylinder. The adjusted finite element model predicted an increase in buckling load of 18 percent compared to the baseline cylinder as a result of this load redistribution.","Composites; Advanced Fiber Placement; Variable Stiffness; Cylinder; Cone; Optimization; Modal Test; Bending Test","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures","","","",""
"uuid:0cc58fc4-1c8b-49c4-82d6-a7c59090ee97","http://resolver.tudelft.nl/uuid:0cc58fc4-1c8b-49c4-82d6-a7c59090ee97","Lay-up Optimisation of Fibre Metal Laminates: Development of a Design Methodology for Wing Structures","Şen, I.","Benedictus, R. (promotor); Alderliesten, R.C. (promotor)","2015","The lower wing skin is one of the primary structures of an aircraft. To further improve the fatigue and damage tolerance (F&DT) performance of the lower wing, fibre metal laminates (FML) are proposed as a new material solution. FML consist of thin metal layers bonded with layers of fibre composites. This concept has potentially a large design freedom and its layups could be tailored for specific applications by varying the number, thickness, orientation, and material type of the metal and fibre constituents. This study has been performed to explore the possibilities of lay-up optimisation for FML and to apply the concept of FML to a wing structure. This research aimed to develop a design optimisation methodology for FML that satisfies F&DT criteria. The optimisation methodology should reveal the contribution of individual criteria to the obtained solutions. Furthermore, the method will be used to design a lower wing skin consisting of FML where F&DT and additional compatibility criteria are met. As a result, an analytical model is developed that comprises all the functionality to design a wing structure consisting of FML lower panels and aluminium upper panels. The lay-up solutions are obtained by evaluating the laminates for fatigue crack initiation (FCI), fatigue crack propagation (FCP) and residual strength (RS). These properties are obtained by means of prediction methods, which are implemented into a genetic algorithm optimisation environment. The scientific contribution is delivered by developing a method to reverse the prediction methods to find the lay-ups that satisfy the required property instead of determining the properties of a given lay-up. The lay-up solutions are defined by three parameters: thickness of metal layers, number of metal layers and the grade of a laminate. The amount and orientation of the fibre plies are defined in this grade. With the optimisation method, the lowest weight solution in the design space is determined by generating solutions based on crossover and mutation operators and ranking the satisfying solutions based on their weight. The method considers the optimisation of flat-plates and wing cross-sections. For cross-section optimisation, only the numbers of metal layers along the cross-section are optimised to comply with manufacturing constraints. Additionally, a thickness step constraint is introduced to prevent stress concentrations between elements and to force a distributed thickness along the cross-section. As a final step, the cross-section optimisation is linked to a wing design module that is now capable of dimensioning an aircraft wing structure with the lower panel consisting of FML and the upper panel of aluminium. The thickness of the aluminium skin is defined as variable for the upper skin and evaluated using buckling criteria. As output, a complete optimised cross-section is obtained. To further improve the computation time and to simply the optimisation routine, a regression analysis is performed on the prediction methods for FCI, FCP and RS to obtain approximations for these methods. These approximate functions replace the prediction methods with high correlation and with assurance that the same solutions are obtained as output. The functions are replaceable with other functions representing different criteria to have a generic design method. The influence of optimisation settings, approximations and different design criteria are extensively investigated. The output of the design method depends on the accuracy of the prediction methods and the accuracy of the performed regression, because a small difference in prediction influences the obtained optimal and near optimal design solutions. Further, genetic algorithm proved to be a robust method when optimising single elements or flat-plates when the settings are well-defined. In case of cross-section optimisation, due to the increasing size of the design space the method proved to be inefficient sometimes with the case that once in a while satisfying solutions were not obtained or were stuck at local minima. This problem is solved by defining an initial input to the procedure and increasing or decreasing the upper and lower boundary of the design space. A convergence loop for genetic algorithm is implemented to automate this process in this design method. In conclusion, the method has the ability to compare and evaluate material configurations, to investigate the influence of various design criteria on the lay-up solutions and to optimise the wing material for minimised weight for different sets of load cases and wing geometries.","Fibre Metal Laminates; Lay-up Optimisation; Fatigue & Damage Tolerance; Wing Design; Ilhan Sen","en","doctoral thesis","","","","","","","","2015-10-23","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:f0228918-d5c2-46ed-adf0-976dd825050a","http://resolver.tudelft.nl/uuid:f0228918-d5c2-46ed-adf0-976dd825050a","Compressive Failure Behaviour of Novel Aramid Fibres","Knijnenberg, A.","","2009","Since the development of the first truly synthetic fibres in the late nineteenth century, scientific efforts have lead to large variety of fibres ranging from fibres for textile applications to high performance fibres used as engineering materials. Examples of high performance fibres that are often used in engineering applications are aramid, glass and carbon fibres. Based on specific tensile properties polymer fibres such as aramids outperform glass and carbon fibres, but a major concern is, however, their behaviour under compressive loading. The work presented in this thesis describes a novel approach to increase the compressive strength of aramid (or PPTA) fibres and to characterise the compressive failure behaviour of these new fibres in more detail. The new concept is based on the addition of PPTA-compatible oligomers containing reactive end-groups. These newly designed oligomers can be considered to act as a molecular ‘glue’ to locally increase lateral cohesion and hence to increase the compressive properties without reducing the axial tensile properties.","aramid; compressive failure; compressive strength; fibre; lateral interaction; oligomer; radial texture","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Fundamentals of Advanced Materials","","","",""
"uuid:29e86b3f-fee4-41e9-9b56-cda14ef928fb","http://resolver.tudelft.nl/uuid:29e86b3f-fee4-41e9-9b56-cda14ef928fb","Thermoplastic Composite Wind Turbine Blades: Kinetics and Processability","Teuwen, J.J.E.","Beukers, A. (promotor); Bersee, H.E.N. (promotor)","2011","In previous research, the potential of glass fibre reinforced anionic polyamide-6 (APA-6) composites for use in wind turbine blades was proven. Based on polymer properties, viscosity, processing time, costs and recyclability, APA-6 composites are considered the most suitable reactive thermoplastic material candidate. However, more research is needed to mature the knowledge of the APA-6 material and its processing which can be achieved by understanding the effect of the individual steps in the manufacturing process and by studying the material behaviour in more detail. First of all, an experimental study on the effect of the individual steps in the manufacturing and post-processing process was performed to increase the homogeneity of the composites and identify the most important processing parameters. Secondly, semi-empirical models for the prediction of the reaction kinetics and rheology were built to better estimate the infusion time, start of reaction and the behaviour of the material. These models were then used to predict the heat build-up due the exothermic reaction in thick-walled composites. Based on the models for the reaction kinetics and rheology and the knowledge build from the experimental investigation, it is thought that an optimisation of the whole manufacturing process for a specific product is feasible and that the material behaviour within that process can be well predicted.","thermoplastic composites; vacuum infusion; reaction kinetics; process optimisation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Design and Production of Composite Structures","","","",""
"uuid:e592b6f1-7f0f-499b-a985-2705a7a2ecba","http://resolver.tudelft.nl/uuid:e592b6f1-7f0f-499b-a985-2705a7a2ecba","Gradient-based approximate design optimization","Vervenne, K.","Van Keulen, F. (promotor)","2005","The research presented in this thesis deals with gradient-enhanced approximate design optimization. This research has been carried out as part of the ADOPT project (Approximate Design OPTimization), a joint STW project with the Eindhoven University of Technology. In structural optimization, sensitivity analysis is often performed by means of the semi-analytical method. In the present thesis it has been shown that the accuracy of the design sensitivities can be improved by using Laplacian smoothing instead of a boundary node approach. In many applications of structural optimization, sensitivity information is available at low computational cost. Various methods to include this information in the response surface method have been investigated. It has been shown that including gradient information in the response surface may be considered as a multi-objective optimization problem, in which a trade-off between accuracy in function values and gradients has to be made explicitly. In addition, the use of fast reanalysis is considered in order to reduce the computational time required to carry out the function evaluations. As an application, the optimization of composite laminates has been considered. These types of problems lead to a non-smooth response. It has been investigated whether an optimizer based on a sequential approximate method can be used to solve these types of problems. The proposed approach has been applied to the optimization of composite tubes.","gradient; response surface; design optimization","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e1b24918-3b46-471c-a5ba-70b9c7f99d23","http://resolver.tudelft.nl/uuid:e1b24918-3b46-471c-a5ba-70b9c7f99d23","Adaptive self tuning flight control systems: The multiple model approach","Abidin, Z.","Mulder, J.A. (promotor); Honderd, G. (promotor)","1998","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6d9c2f9e-358f-4398-8daa-c37004c816ae","http://resolver.tudelft.nl/uuid:6d9c2f9e-358f-4398-8daa-c37004c816ae","Optimum Design of Steered Fibre Composite Cylinders with Arbitrary Cross-sections","Khani, A.","Gurdal, Z. (promotor)","2013","Automated fibre placement (AFP) machines are able to place simultaneously several bundles of fibres, called tows, on a surface. Using AFP machines, it is also possible to manufacture composite laminates with fibres placed in curvilinear paths. The fibre orientations and stiffness properties of these laminates are spatially varied and hence they are called variable stiffness (VS) laminates in contrast to the traditional laminates with straight fibres which are called constant stiffness (CS) laminates. Past research has shown that the structural performance of laminated composite structures can be improved by spatial tailoring of laminate stiffness. One of the widely used structural components in aerospace industry are cylindrical shells. In this thesis, a computationally efficient framework was developed for circumferential laminate stiffness tailoring of unstiffened and longitudinally stiffened cylindrical shells with arbitrary cross sections to maximise the buckling capacity with consideration of strength constraints. In addition, the AFP manufacturing constraint on the maximum curvature of curvilinear fibre paths was considered. This constraint was applied to avoid wrinkling of the fibres placed inside the turn of a curved tow. The aforementioned framework utilised computationally efficient analysis and optimisation tools.","variable stiffness; cylindrical shells; fibre steering; fibre placement; buckling; strength","en","doctoral thesis","","","","","","","","2014-12-10","Aerospace Engineering","Aerospace Structures and Computational Mechanics Group","","","",""
"uuid:237176b3-b8b1-40d9-b83d-373ebcad199a","http://resolver.tudelft.nl/uuid:237176b3-b8b1-40d9-b83d-373ebcad199a","Recovery and recrystallization in C-Mn steels following hot deformation","Smith, A.","van der Zwaag, S. (promotor)","2006","Abstract not available","recrystallization; recovery; steel; stress relaxation; laser-ultrasonics; intercritical deformation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e81178af-32f8-4ce9-89c0-09fa23ced59a","http://resolver.tudelft.nl/uuid:e81178af-32f8-4ce9-89c0-09fa23ced59a","The least-squares spectral element method: Theory, implementation and application to incompressible flows","Proot, M.M.J.","Bakker, P.G. (promotor)","2003","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:17214b06-3b53-4315-a2e3-41e4f031f6f4","http://resolver.tudelft.nl/uuid:17214b06-3b53-4315-a2e3-41e4f031f6f4","The Imperfection Data Bank and its Applications","Vries, J. De","Gürdal, Z. (promotor); De Boer, A. (promotor)","2009","Imperfections are irregularities of the shape of a thin-walled shell, such as those used for rocket structures or silos. Knowing the imperfections is very important as thin-walled shells are very sensitive to imperfections. Even a small deviation with respect to the perfect shell shape reduces the buckling load significantly. The main objective of this thesis is to describe the creation of an imperfection data bank and tools to process the data. Point of investigation is the question if the shell buckling knock-down factor that accounts for the degrading affect of the geometric imperfections, can be optimized. The current factor is too conservative for most of the shells. This is caused by the fact that the knock-down factor, as can be found in the NASA report SP-8007, is based on old testdata. It has also been shown that similar shells have similar imperfections. It would be very interesting which imperfection are caused by a certain production process. In this thesis it has been shown that the imperfections are not related to where a shell was produced. Using the state of the art technology to produce new shells the usage of the common design curves. i.e. the lower bound curves would yield a very conservative, too heavy, design.","imperfection data bank; lower bound; buckling","en","doctoral thesis","","","","","","","","2009-05-11","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:e71dff4d-abf9-475f-bc4d-78317751586a","http://resolver.tudelft.nl/uuid:e71dff4d-abf9-475f-bc4d-78317751586a","An adjoint-based shape-optimization method for aerodynamic design","Carpentieri, G.","Van Tooren, M.J.L. (promotor); Koren, B. (promotor)","2009","This thesis presents a shape optimization framework for problems that are encountered routinely in Aerodynamic Design. The nature of the framework is numerical. Its focus is wide as different aspects of the shape optimization practice are treated, e.g., the solution of the flow equations, the sensitivity analysis and the parameterization of the shape. The framework components are not taken as black-boxes but are conceived and implemented within the present work. A considerable part of the thesis describes the characteristics and the implementation of those components. Additional work on unsteady flows, which may find applications in aeroelastic analysis, is presented in the appendix.","Euler equations; Computational Fluid Dynamics; Adjoint equations; Finite-volume method; Shape Optimization; Shape Parameterization","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Design of Aircraft and Rotorcraft","","","",""
"uuid:66e210e1-c884-45d6-b9d4-711907680452","http://resolver.tudelft.nl/uuid:66e210e1-c884-45d6-b9d4-711907680452","Mode I fatigue delamination growth in composite laminates with fibre bridging","Yao, L.","Benedictus, R. (promotor)","2015","Advanced composite materials have been commonly used in aerospace engineering, because of their good mechanical properties and attractive potential for creating lightweight structures. Susceptibility to delamination is one of the most important issues in the applications of these materials. This disadvantage can prohibit the application of composite materials in primary aerospace structures and limit their lightweight potential. Therefore, characterizing fatigue delamination growth behavior in composite laminates is important for the applications of these materials in aerospace, as it provides the necessary information for the damage tolerance design philosophy. Fibre bridging is an important shielding mechanism during delamination growth in composite laminates. It can increase the fracture toughness by restraining the crack opening and inhibit delamination growth. However, there is no reliable method to take into account of its contribution to fatigue delamination growth. Thus, investigation of this phenomenon and development of a prediction method is required. The objective of this investigation is to study mode I fatigue delamination growth with fibre bridging in composite laminates and provide physics-based interpretations of fatigue delamination growth. Two approaches are applied to interpret the fatigue delamination growth behavior according to different perspectives. In the engineering perspective, the Paris relation is applied. However, in the physics-based perspective, energy principles are used. The bridging effect on fatigue delamination growth is first investigated by a series of fatigue tests. The Paris relation is used to interpret the fatigue data. It demonstrates that fibre bridging can significantly decrease the fatigue crack growth rate, making it invalid to use a single fatigue resistance curve to determine fatigue delamination with bridging. A new method, still based on the Paris relation, is developed to predict fatigue delamination growth with fibre bridging, by correlating the curve fitting parameters with the amount of bridging fibres. Fatigue delamination growth is physically explained according to the energy conservation law. It is found that bridging fibres periodically store and release strain energy upon loading and unloading cycles. However, they have no contribution to the real strain energy release, unless the bridging fibre pullout or fails. This can lead to the invalidity of using the strain energy release rate (SERR) determined by the fixed grip assumption for quasi-static crack growth to interpret fatigue crack growth. Therefore, the SERR commonly used is not a suitable similitude parameter to determine fatigue delamination growth. Energy principles are subsequently used to interpret the stress ratio effect in fatigue delamination growth. A concept of fatigue fracture toughness is proposed to describe the steady fatigue delamination growth, in which little or no bridging fibre pullout or failure occurs. Therefore, all energy dissipation in the steady delamination growth is concentrated on the new crack generation. The fatigue fracture toughness is observed to be interface configuration independent but significantly stress ratio dependent. The mechanisms related to this are interpreted by fractographic observation. Using the concept of fatigue fracture toughness, the stress ratio effect on fatigue delamination growth can be explained with a clear physical background.","fatigue; delamination; fibre bridging; composite laminates","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:24e0ed49-7694-43d9-a054-b651dca46171","http://resolver.tudelft.nl/uuid:24e0ed49-7694-43d9-a054-b651dca46171","Digital holographic interferometry in compressible flow research; Digitale holografische interferometrie voor het experimentele onderzoek van samendrukbare stromingen","Lanen, T.A.W.M.","Bakker, P.G. (promotor)","1992","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:70dd07b1-b5b5-4562-ae6e-6bb1a10c28ef","http://resolver.tudelft.nl/uuid:70dd07b1-b5b5-4562-ae6e-6bb1a10c28ef","The development of rubber forming as a rapid thermoforming technique for continuous fibre reinforced thermoplastic composites: Quality control by process control","Robroek, L.M.J.","De Jong, Th. (promotor); Marissen, R. (promotor)","1994","","Composietmaterialen; thermovormen; vezelversterkte kunststoffen; produktietechnieken","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d01156c9-79a7-4ed5-bb25-73e9a0507dea","http://resolver.tudelft.nl/uuid:d01156c9-79a7-4ed5-bb25-73e9a0507dea","Filiform corrosion of aluminium alloys: The effect of microstructural variations in the substrate","Mol, J.M.C.","Van der Zwaag, S. (promotor); De Wit, J.H.W. (promotor)","2000","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9aabcd0f-d984-4d7f-8567-677689e07c85","http://resolver.tudelft.nl/uuid:9aabcd0f-d984-4d7f-8567-677689e07c85","GPS-based precise orbit determination and accelerometry for low flying satellites","Van den IJssel, J.A.A.","Ambrosius, B.A.C. (promotor)","2014","Atmospheric density models are currently the limiting factor in the accuracy of the dynamic orbit determination and prediction of satellites in a low Earth orbit. Any improvement in these models would greatly aid in applications such as re-entry prediction, ground-track maintenance of Earth observation satellites and forecast of possible collisions with space debris objects. Because of their use in scientific studies, improving these models will also bene?t our understanding of the physical processes that occur in the Earth’s upper atmosphere. Accelerometer instruments onboard of low Earth orbiting satellites are near perfect instruments for studying atmospheric density. They provide accurate observations of the non-gravitational accelerations acting on a satellite and for low flying satellites atmospheric drag is the dominant non-gravitational force. Unfortunately, the number of satellites equipped with an accelerometer is limited. Therefore, in this thesis a strategy is developed and implemented to optimally derive non-gravitational accelerations from precise GPS satellite tracking observations of low flying satellites. This estimation of non-gravitational accelerations using a precise GPS-based orbit determination scheme is referred to as GPS-based accelerometry. The developed GPS-based accelerometry processing strategy is applied to GPS data from the CHAMP, GRACE and GOCE satellites. These satellites carry electrostatic accelerometer instruments, which allows a validation of the GPS-based accelerometry performance. This validation shows that best results are generally obtained for lower flying satellites, due to the increased effect of drag at lower altitudes. In general, best performance is obtained in flight direction, due to the strong effect of accelerations in this direction on orbital dynamics. A comparison with state-of-the-art non-gravitational models shows that for all selected satellites, GPS-based accelerometry outperforms the non-gravitational models in the flight direction. These results indicate that with GPS-based accelerometry, satellites equipped with accurate GPS tracking instrumentation can contribute significantly to atmospheric density modeling. With the growing number of satellites equipped with accurate GPS receivers, this strategy could be applied to a large range of satellites, which offers great potential for the improvement of atmospheric density models.","GPS; precise orbit determination; accelerometer; satellite; atmospheric density model","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:16e9508b-a7b7-4ae8-b4ba-2500bbac8582","http://resolver.tudelft.nl/uuid:16e9508b-a7b7-4ae8-b4ba-2500bbac8582","Collapse of anisotropic cylindrical shells under combined bending and transverse shear load","Jamal, A.","Arbocz, J. (promotor)","1998","","buckling; bending; transverse shear; anisotropic; cylindrical shells","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:77630992-2781-4c90-8bc5-964e685f5d72","http://resolver.tudelft.nl/uuid:77630992-2781-4c90-8bc5-964e685f5d72","Structured Piezoelectric Composites: Materials and Applications","Van den Ende, D.A.","Van der Zwaag, S. (promotor)","2012","The piezoelectric effect, which causes a material to generate a voltage when it deforms, is very suitable for making integrated sensors, and (micro-) generators. However, conventional piezoelectric materials are either brittle ceramics or certain polymers with a low thermal stability, which limits their practical application to certain specific fields. Piezoelectric composites, which contain an active piezoelectric (ceramic) phase in a robust polymer matrix, can potentially have better properties both thermally and mechanically than the present single-phase piezomaterials, and yet exhibit sufficient piezoelectricity. The two main objectives of this thesis were to find new routes for manufacturing piezoelectric ceramic-polymer composites with adequate piezoelectric properties while retaining ease of manufacturing and explore new applications using these composites. It was found that a composite with piezoelectric particles dispersed in a high performance polymer matrix possessed improved thermomechanical properties such as thermal stability and temperature dependence of the output signal compared to conventional materials. The added flexibility of piezoelectric composites leads to a greater choice in device geometry and compatibility with polymer processing. Dielectrophoretic (electric field assisted) processing of piezocomposites results in increased permittivity and piezoelectric constants compared to conventional piezoelectric composites with randomly oriented particles, at little added processing complexity. A high degree of alignment could also be achieved using elongated piezoelectric particles, with a significant improvement in piezoelectric properties as a result. As an example, dielectrophoretically processed composites were used as energy harvesting materials in automobile tyres. Energy harvesting materials convert a small amount of energy from the environment to electricity, which can be used to power electronics such as wireless sensors. In automobile tyres, low frequency, high strains are present from which electricity can be generated using the piezoelectric effect. However, these high strains place stringent demands on the materials with respect to mechanical failure or depolarization, especially at elevated temperatures, so conventional piezomaterials are not robust enough to use. After testing inside automobile tyres the energy density of the piezoelectric ceramic-polymer composite materials is comparable to the reference materials and the output of the new piezoelectric ceramic-polymer composites did not degrade during operation. Therefore, these new materials open up new application fields for piezoelectric sensing and energy harvesting.","Piezoelectric; Composites; Dielectrophoresis; Connectivity; Electric field structuring; Sensors; Energy harvesting; Adhesion; Friction","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Novel Aerospace Materials","","","",""
"uuid:d44876fe-45dd-44ae-8947-622613eb963c","http://resolver.tudelft.nl/uuid:d44876fe-45dd-44ae-8947-622613eb963c","Harnessing the potential of Knowledge Based Engineering in manufacturing design","Van den Berg, T.","Van Tooren, M.J.L. (promotor)","2013","An increase in productivity is required for the European aviation industry to remain competitive in a world with rising competition, shorter development timescales, more complex products and decreasing numbers of technically skilled personnel. Fokker Elmo, a Dutch aircraft electrical wiring harness manufacturer, is facing these challenges. At present, preparing a wiring harness for manufacturing is a repetitive, time-consuming and mostly manual, experience-based process. The research presented in this thesis aims at developing techniques to largely automate the generation of wiring harness manufacturing drawings, using Knowledge Based Engineering (KBE). A development approach is proposed as well as KBE building blocks. Three KBE applications are developed and tested that offer functionalities not present in general-purpose CAD systems. These applications can considerably reduce the amount of repetitive work, while ensuring compliance to physical constraints and manufacturing guidelines.","Knowledge Based Engineering; search; manufacturing; automation; wiring; formboard","en","doctoral thesis","","","","","","","","2013-12-18","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:41b62a9a-c15e-4026-b600-66ca4701941c","http://resolver.tudelft.nl/uuid:41b62a9a-c15e-4026-b600-66ca4701941c","Filament Winding. A Unified Approach","Koussios, S.","Beukers, A. (promotor); Gurdal, Z. (promotor); Van Tooren, M.J.L. (promotor)","2004","In this dissertation we have presented an overview and comprehensive treatment of several facets of the filament winding process. With the concepts of differential geometry and the theory of thin anisotropic shells of revolution, a parametric shape generator has been formulated for the design procedure of optimal composite pressure vessels in particular. The mathematical description of both geodesic and non-geodesic roving trajectories has been presented, including a proposal for a mandrel shape that facilitates the experimental procedure for the determination of the coefficient of friction. In addition, an overview of several (non-) geodesic trajectories is here given. Furthermore, an algorithm for the automatic generation of suitable winding patterns has been outlined, in combination with several pattern optimisation strategies. An extensive treatment of the kinematics of filament winding is here presented, in combination with several recommendations for a proper derivation of the associated velocities and accelerations to which the moving machine parts and the roving itself are subjected. A simplified collision control module has resulted in the determination of the limits where the feed eye is allowed to move in. Within this space and with the dynamic machine limits, an optimisation problem has been set up, serving the aim of production time minimisation. This has been achieved by application of dynamic programming that minimises a summation of constraint respecting time increments, after the realisation of a grid-reduction with a technique that is based on elementary sparse matrix multiplication. Furthermore, several novel machine configurations have been proposed, which are dedicated to pressure vessels with various aspect ratios, shape morphology and types of applied wound circuits. With the shell equilibrium equations as a basis, we have derived the class of articulated pressurisable structures, comprising isotensoids that are axially stacked on each other. Moreover, the non-geodesically overwound isotensoid has been introduced, together with a variant being additionally subjected to external radial forces. The same equilibrium equations have generated shapes like the geodesically overwound hyperboloid and optimal toroidal pressure vessels. Furthermore, we have proposed several application fields for these items. As a leitmotiv throughout the thesis, the derived methodologies and equations have been applied on the class of isotensoid pressure vessels. The results generated by the roving trajectories description modules and pattern generation algorithms are verified by simulation, while the results of the kinematic solver and the optimiser are evaluated by both simulation and implementation on a winding machine. However, mechanical testing of the proposed structures and test-running of the introduced machine configurations must here be left over to the recommendations.","filament winding; pressure vessel design; production process; optimisation","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8a938547-a829-4a79-b77c-a92633a9652a","http://resolver.tudelft.nl/uuid:8a938547-a829-4a79-b77c-a92633a9652a","Airfoil Self-Noise - Investigation with Particle Image Velocimetry","Pröbsting, S.","Scarano, F. (promotor)","2015","Noise generated aerodynamically by the airflow over a lifting surface is often of concern for applications as diverse as air and ground transportation, heating, ventilation, air-conditioning systems, and wind turbines. The thesis describes the application of advanced optical flow measurements techniques for the visualization and description of the sources of sound on airfoils. These measurement techniques include high-speed stereoscopic and tomographic Particle Image Velocimetry (PIV) together with advanced methods for post-processing to obtain a representation of the aeroacoustic source field. Following this innovative and evolving approach in experimental aeroacoustics, a novel methodology for broadband trailing-edge noise diagnostics by tomographic PIV is proposed. Moreover, on the basis of simultaneous high-speed PIV and acoustic measurements, new and fundamental insights into the mechanism of tonal noise generation due to the interaction of amplified laminar boundary layer instability waves with the trailing edge are presented. Both examples demonstrate the potential impact of advanced PIV methods on present and future research in experimental aeroacoustics.","aeroacoustics; particle image velocimetry; fluid mechanics; trailing edge noise; airfoil self-noise","en","doctoral thesis","","","","","","","","2016-08-01","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","","",""
"uuid:300360b9-e534-4a45-8fd7-9fa8beebd0ef","http://resolver.tudelft.nl/uuid:300360b9-e534-4a45-8fd7-9fa8beebd0ef","High order mimetic discretization; development and application to Laplace and advection problems in arbitrary quadrilaterals","Palha, A.","Bijl, H. (promotor); Gerrtitsma, M.I. (promotor)","2013","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:32fab147-6545-4926-819f-f23741ad83a7","http://resolver.tudelft.nl/uuid:32fab147-6545-4926-819f-f23741ad83a7","Numerical simulation of crack growth in pressurized fuselages","Knops, H.A.J.","Arbocz, J. (promotor)","1994","","breuken (mechanica); vliegtuigbouw","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:12001adc-ef88-4325-865c-ef8e7767903b","http://resolver.tudelft.nl/uuid:12001adc-ef88-4325-865c-ef8e7767903b","Stuurstandslijnen van vliegtuigen: De bepaling ervan door middel van vliegproeven en hare beteekenis voor de beoordeling der stabiliteit","Van der Maas, H.J.","Burgers, J.M. (promotor)","1929","","","nl","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:022e1a88-f48e-493e-805e-014f396a05dc","http://resolver.tudelft.nl/uuid:022e1a88-f48e-493e-805e-014f396a05dc","Low-velocity impact on fibre-metal laminates","Moriniere, F.D.","Benedictus, R. (promotor); Alderliesten, R.C. (promotor)","2014","Generating high-energy absorbing FML concepts is challenging because aluminium and composite failure mechanisms are acting concurrently during the impact process. Because the impact process involves energy transformation, an analytical energy balance method was used to assess the contribution of the material constituents in the low-velocity impact energy absorption. The energy approach was combined with a structural approach using the Classical Laminate Theory. This theory covers out-of-plane deformation cases that can be used for impact studies. Corresponding to this out-of-plane displacement, strain energy was balanced with the energy due to delamination to obtain the absorbed energy. The generic quasi-static energy balance model predicted accurately the low-velocity impact behaviour of FMLs under large mass. The theoretical energy partition among the material constituents was revealed to substantiate firm conclusions on the impact resistance of FMLs. The excellent impact resistance of FMLs is not only due to the increasing strength of glass composites when loaded at higher strain rates. The inner composite plies absorb a minor portion of the impact energy and they direct the impact load in the plate's plane. The outer metal layers limit the extent of delamination and undergo large global displacement before fracture. Due to the generic nature of the developed approach, it was possible to implement minor modifications to predict the low-velocity impact behaviour of an FML-based sandwich structure.","fibre-metal laminate; low-velocity impact; generic model; energy balance","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:028b7ceb-37eb-4a72-a6c2-67951a4e82eb","http://resolver.tudelft.nl/uuid:028b7ceb-37eb-4a72-a6c2-67951a4e82eb","Investigations on the transonic flow around aerosoils","Spee, B.M.","Steketee, J.A. (promotor)","1969","The question of the stability of steady compressible two-dimensional potential flows with embedded regions of supersonic flow adjacent to a body is examined. The behaviour of unsteady disturbances is investigated and an essential difference between the stability of transonic one-dimensional and two-dimensional flow is shown to exist. It is shown that two-dimensional transonic potential flows are stable. An experimental investigation on quasi-elliptical aerofoil sections is discussed. The results of this investigation suggest that the theoretical potential flows can be approached arbitrarily close. It is concluded that the use of potential flow theory in the transonic region is equally acceptable as anywhere else in aerodynamics.","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a699e4a5-9ff6-4ba5-8238-e41772cefe2a","http://resolver.tudelft.nl/uuid:a699e4a5-9ff6-4ba5-8238-e41772cefe2a","The Residual Strength Failure Sequence in Fibre Metal Laminates","Rodi, R.","Benedictus, R. (promotor)","2012","The concept of damage tolerance is a key aspect in ensuring and maintaining safety of an airframe structure over its design life. Developments in materials and structural design have both contributed to improvements in the damage tolerance of modern aircraft structures. Indeed, new developments in metal alloys, composite materials, and hybrid materials such as the Fibre Metal Laminates (FMLs) have all resulted in structures less sensitive to damage and capable to withstand more severe loading conditions. Among other materials, FMLs represent a clear example of damage tolerant hybrid materials, made by bonding thin metal sheets together with fibres embedded in epoxy. Exploiting the damage tolerance capability of FMLs is strictly related to the ability to firstly understand the occurring failure mechanisms, and secondly to be able to accurately describe those mechanisms. In this light, the present dissertation describes the investigation on the residual strength failure sequence in FMLs, and presents the development of an accurate analytical prediction method. The failure sequence is studied in particular for standard Glare laminates, which are relevant laminates for applications in aircraft pressurized fuselages. The developed analytical method has been implemented into two numerical models, considering both through-the-thickness crack and fatigue crack configurations. The developed models are validated against a large number of experimental data, which are also presented in this thesis. The main concept in this dissertation is that the crack growth process in the metallic layers of an FML can be described with the Crack Tip Opening Angle concept (CTOA). This approach includes the contribution of the fibre layers (e.g. fibre failure and fibre bridging) and the associated quasi-static delamination growth. An introduction to FMLs and to all various Glare grades, lay-ups, and manufacturing processes is provided in chapter 2. Some current and future applications for aircraft structures are also discussed in that chapter. A qualitative description of the principal failure mechanisms occurring during the residual strength failure sequence is presented in chapter 3. Based on experimental observations, the metal crack growth mechanisms, permanent plastic deformation, fibre failure and static delamination growth are discussed. All these mechanisms are related to each other, and all contribute to the residual strength of the laminate. The development of the prediction models aimed to be a step forward with respect to previous relevant prediction models available in literature. Therefore, both empirical and analytical prediction models available in literature are presented and discussed in chapter 4. A critical evaluation of those models has pointed out their limitations in applicability and versatility towards a “generic FML” concept. From this chapter, some guidelines have been defined to address the subsequent model development. Two types of experimental activities were carried out. The first type consisted in experiments to gain understanding of the deformation behaviour of both metallic and fibre layers. Extensive use of Digital Image Correlation technique enabled to observe and measure the deformation field of both metal and fibre layers, and their interaction. Further insight into the fibre bridging mechanism and into the metal-fibre interaction was obtained. These experimental activities are discussed in chapter 5. The second type of experimental activities aimed to generate input data for the prediction model, and to validate the CTOA approach. These are discussed in chapter 6. A large amount of experimental CTOA tests were conducted on several FML grades to evaluate the CTOA as failure criterion for FML. This included the investigation of the effect of metal sheet thickness, crack length-to-panel width ratio and the effect of bridging fibres. Static delamination growth tests were conducted to obtain the critical Strain Energy Release Rate. This parameter was subsequently used as input in the prediction model to define the critical condition for the delamination growth. Furthermore, in the same chapter, it is also discussed the complex interaction between static delamination growth and plastic deformation of the metallic layers. The core aspect of the present thesis concerns the modelling of the residual strength failure sequence, which is presented in chapter 7. Two models are described: one for the through-the-thickness crack and one for the fatigue crack. Both models are based on the same method, which uses the CTOA as crack growth driving parameter. The method is based on the idea that crack extension in the metallic layers occurs when the calculated CTOA reaches the critical value obtained from CTOA experiments on metal laminates containing the same metal layers used in the FML. The calculated CTOA is a function of the contribution due to the far-field stress in the aluminium layers, and the contribution of the fibres. The fibre can contribute either in terms of crack opening contribution (broken fibres) or crack closing contribution (bridging fibres present in the fatigue crack configuration). Plastic deformation ahead and behind the metal crack tip is accounted and implemented into the calculation. In addition, in the case of fatigue crack configurations, the bridging stress is calculated by solving the deformation compatibility equation, accounting for the plastic zone ahead of the crack tip and fibre failure in the bridging area. The bridging stress is subsequently used to calculate the quasi-static delamination growth occurring at the fibre-metal interface using the Strain Energy Release Rate approach. The model for through-the-thickness crack showed a very good agreement with the experimental data, while the model for fatigue crack configuration showed sufficient agreement with experimental data. The modelling of the fatigue crack configuration presents higher degree of complexity, which required a number of simplifications and assumptions, making the model less robust than the one for through-the-thickness crack. Chapter 8 summarises the conclusions of the investigations. It can be concluded that with the proposed models, the mechanisms related to the residual strength failure sequence are fully described and characterized. The model for through-the-thickness crack is robust and validated, and can be extended to other material and geometrical configurations. The model for fatigue crack is not robust enough, but further improvements are possible.","Fibre metal laminates","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:4446cae2-fe60-464f-ab2e-d7282093616d","http://resolver.tudelft.nl/uuid:4446cae2-fe60-464f-ab2e-d7282093616d","Modelling and simulation of turbulence and heat transfer in wall-bounded flows","Popovac, M.","Hanjalic, K. (promotor)","2006","At present it is widely accepted that there is no universal turbulence model, i.e. no turbulence model can give acceptably good predictions for all turbulent flows that are found in nature or engineering. Every turbulence model is based on certain assumptions, and hence it is aimed at certain type of flows for which it recovers the effects that are occurring in that flow. The work presented in this thesis aims at improving the turbulence modelling applicable to the complex wall-bounded engineering flows and heat transfer. However, the basic requirement for the development of a new turbulence model is the understanding of the fundamental fluid flow principles. Therefore this work also presents a detailed analysis of a complex wall-bounded flow and heat transfer with multiple flow phenomena. The proposed turbulence model is a robust and reliable modification of the elliptic relaxation eddy-viscosity model, which gives accurate flow and heat transfer predictions in complex wall-bounded flows. In order make this model suitable for engineering computations, the compound near-wall treatment is presented, which makes flow predictions insensitive to the quality and resolution of the computational mesh used in the near-wall region. Both turbulence model and near-wall treatment are tested on several generic non-equilibrium test flows. Originating from the electronics industry applications, this thesis also gives LES study of the vortical structures and heat transfer in the case of the cooling of one in a series of wall-mounted cubes placed in an array on the wall of a channel flow by a round impinging jet. The geometry in this numerical analysis is defined by an in-line array of five cubes mounted on the wall of a plane channel. The central cube consists of the copper core and a layer of epoxy around the core, and only this cube is heated by specifying the constant temperature of the copper core. This cube is cooled by two mutually perpendicular streams: a channel flow parallel to the mounting wall, and a round impinging jet issued from the orifice which connects the channel with cubes and the chamber placed above it. There are several flow structures occurring in this flow, such as roll-up vortex rings, impingement, separation and reattachment, which dictated the conjugate heat transfer from the central heated cube.","rans; les; cfd; integration to the wall; wall functions; compound wall treatment","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9ed5a294-c652-4868-8cd4-3c8d0802624e","http://resolver.tudelft.nl/uuid:9ed5a294-c652-4868-8cd4-3c8d0802624e","Modelling and Simulation of Decomposition Reactions","van der Heijden, J.C.","Hoeijmaker, H.W.M. (promotor)","1997","","","en","doctoral thesis","Delft University of Techology, Faculty of Aerospace Engineering","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8c7de90e-a299-4394-806a-a15f9a0aecfe","http://resolver.tudelft.nl/uuid:8c7de90e-a299-4394-806a-a15f9a0aecfe","Numerical analysis of failure mechanisms in fibre metal laminates","Hashagen, F.","De Borst, R. (promotor); Vogelesang, L.B. (promotor)","1998","","fibre metal laminates; finite elements shell theory; cracking; delamination; plasticity","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a201553c-db89-43ef-a4fd-7ea06eed57cc","http://resolver.tudelft.nl/uuid:a201553c-db89-43ef-a4fd-7ea06eed57cc","Advances in Time-Resolved Tomographic Particle Image Velocimetry","Lynch, K.P.","Scarano, F. (promotor)","2015","This thesis details advanced developments in 3-D particle image velocimetry (PIV) based on the tomographic PIV technique, with an emphasis on time-resolved experiments. Tomographic PIV is a technique introduced in 2006 to measure the flow velocity in a three-dimensional volume. When measurements are performed at a rate high enough to sample the dynamical evolution of the flow, the measurement is considered time-resolved. The present work begins with a description of developments in tomographic PIV since its inception and outlines the working principles. A detailed explanation of the reconstruction and correlation procedures is given. The primary limitations of the technique are identified, and it is hypothesized that new analysis methods exploiting time-resolved image sequences can overcome these limitations. This research characterizes the baseline performance of tomographic PIV, explores this hypothesis for both reconstruction and correlation, and demonstrates a novel system for acquiring time-resolved data in high-speed flows. Even though tomographic PIV has been a topic of research for nearly a decade, its accuracy remains an active area of inquiry. Few studies exist which approach the topic in a parameteric manner using experiments and varying the primary variables including the number of cameras and seeding concentration. Chapter 3 presents a novel experimental assessment of tomographic PIV accuracy, enabled by a 12-camera system as a reference measurement. The reconstruction quality, signal-to-noise ratio, and variance are determined, and the velocity field accuracy is assessed. These analyses provide a set of guidelines for experimentalists in the set-up phase of a measurement campaign. Time-resolved tomographic reconstruction is the focus of chapter 4, where the sequential motion-tracking enhanced (SMTE) reconstruction technique is developed. SMTE is based on a time-marching predictor of the reconstructed intensity field, extending the concept of motion-based predictors from the motion-tracking enhanced (MTE) reconstruction of Novara et al. The novel application to time-resolved data yields significant improvements in reconstruction quality and velocity field accuracy with little or no increase in computational burden. The improvements also allow for operation at higher seeding densities or with fewer cameras. Improvements to the correlation procedure for time-resolved data are introduced in chapter 5. A novel evolution of the image deformation method is proposed to extend correlation-based measurement to account for non-linear fluid trajectories and incorporate information from multiple snapshots. The fluid trajectory correlation (FTC) allows the measurement interval to be enlarged compared to single-pair or ensemble-averaging approaches, and is particularly well-suited for tomographic PIV sequences where no out-of-plane motion allows fluid parcels to be tracked in 3D space over a number of frames. The application of the technique to both synthetic and experimental data sets shows an improvement in measurement dynamic range without compromising the measurement by truncation error. The robustness and accuracy afforded by the aforementioned algorithms are realized only for time-resolved data sets. The use of standard high-speed tomographic PIV equipment in high-speed flows is not possible due to the limited laser power and camera frame rate. In chapter 6 a burst-mode tomographic system able to acquire up 4 pulses within microseconds is developed and demonstrated for the measurement of the instantaneous velocity and material acceleration which is applicable for transonic flows to attempt non-intrusive measurements of unsteady pressure fluctuations. Furthermore, a connection is made to the FTC method of chapter 5 to show the synthesis of novel hardware and software to measure the material acceleration. The work concludes with a summary of the main findings and a perspective on future research directions potentially leading to a broader adoption of the time-resolved tomographic PIV technique.","tomographic PIV","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:2a3631d9-61a2-4167-b510-efa563f991b0","http://resolver.tudelft.nl/uuid:2a3631d9-61a2-4167-b510-efa563f991b0","Aeroacoustic Resonance of Slender Cavities: An experimental and numerical investigation","De Jong, A.T.","Bijl, H. (promotor)","2012","","cavity resonance; aeroacoustics; plasma actuator; trailing edge noise; flow control; Lattice Boltzmann Method; Particle Image Velocimetry","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:a21d2cc6-9924-4018-9387-60527fb27d4b","http://resolver.tudelft.nl/uuid:a21d2cc6-9924-4018-9387-60527fb27d4b","Adaptive Backstepping Flight Control for Modern Fighter Aircraft","Sonneveldt, L.","Mulder, J.A. (promotor); Chu, Q.P. (promotor)","2010","The main goal of this thesis is to investigate the potential of the nonlinear adaptive backstepping control technique in combination with online model identification for the design of a reconfigurable flight control system for a modern fighter aircraft. Adaptive backstepping is a recursive, Lyapunov-based, nonlinear design method, that makes use of dynamic parameter update laws to deal with parametric uncertainties. The idea of backstepping is to design a controller recursively by considering some of the state variables as ‘virtual controls’ and designing intermediate control laws for these. Backstepping achieves the goals of global asymptotic stabilization of the closed-loop states and tracking. The proof of these properties is a direct consequence of the recursive procedure, since a Lyapunov function is constructed for the entire system including the parameter estimates. The tracking errors drive the adaptation process of the procedure. Furthermore, it is possible to take magnitude and rate constraints on the control inputs and system states into account in such a way that the identification process is not corrupted during periods of control effector saturation. A disadvantage of the integrated adaptive backstepping method is that it only yields pseudo-estimates of the uncertain system parameters. There is no guarantee that the real values of the parameters are found, since the adaptation only tries to satisfy a total system stability criterion, i.e. the Lyapunov function. Increasing the adaptation gain will not necessarily improve the response of the closed-loop system, due to the strong coupling between the controller and the estimator dynamics. The immersion and invariance (I&I) approach provides an alternative way of constructing a nonlinear estimator. This approach allows for prescribed stable dynamics to be assigned to the parameter estimation error. The resulting estimator is combined with a backstepping controller to form a modular adaptive control scheme. The I&I based estimator is fast enough to capture the potential faster-than-linear growth of nonlinear systems. The resulting modular scheme is much easier to tune than the ones resulting from the standard adaptive backstepping approacheswith tracking error driven adaptation process. In fact, the closed-loop system resulting from the application of the I&I based adaptive backstepping controller can be seen as a cascaded interconnection between two stable systems with prescribed asymptotic properties. As a result, the performance of the closed-loop system with adaptive controller can be improved significantly. To make a real-time implementation of the adaptive controllers feasible the computational complexity has to be kept at a minimum. As a solution, a flight envelope partitioning method is proposed to capture the globally valid aerodynamic model into multiple locally valid aerodynamic models. The estimator only has to update a few local models at each time step, thereby decreasing the computational load of the algorithm. An additional advantage of using multiple, local models is that information of the models that are not updated at a certain time step is retained, thereby giving the approximator memory capabilities. B-spline networks are selected for their nice numerical properties to ensure smooth transitions between the different regions. The adaptive backstepping flight controllers developed in this thesis have been evaluated in numerical simulations on a high-fidelity F-16 dynamicmodel involving several control problems. The adaptive designs have been compared with the gain-scheduled baseline flight control system and a non-adaptive NDI design. The performance has been compared in simulation scenarios at several flight conditions with the aircraft model suffering from actuator failures, longitudinal center of gravity shifts and changes in aerodynamic coefficients. All numerical simulations can be easily performed in real-time on an ordinary desktop computer. Results of the simulations demonstrate that the adaptive flight controllers provide a significant performance improvement over the non-adaptive NDI design for the simulated failure cases. Of the evaluated adaptive flight controllers, the I&I based modular adaptive backstepping design has the overall best performance and is also easiest to tune, at the cost of a small increase in computational load and design complexity when compared to integrated adaptive backstepping control designs. Moreover, the flight controllers designed with the I&I based modular adaptive backstepping approach have even stronger provable stability and convergence properties than the integrated adaptive backstepping flight controllers, while at the same time achieving a modularity in the design of the controller and identifier. On the basis of the research performed in this thesis, it can be concluded that a RFC system based on the I&I based modular adaptive backstepping method shows a lot of potential, since it possesses all the features aimed at in the thesis goal.","flight control; adaptive control; system identification; backstepping; Lyapunov; nonlinear control","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Control & Simulation","","","",""
"uuid:3869d074-4e3c-4738-b445-15dbdfd51cab","http://resolver.tudelft.nl/uuid:3869d074-4e3c-4738-b445-15dbdfd51cab","A Cybernetic Approach to Assess the Longitudinal Handling Qualities of Aeroelastic Aircraft","Damveld, H.J.","Mulder, J.A. (promotor)","2009","The future demand for larger and lighter civil transport aircraft leads to more flexible aircraft, which bring their own controlling and handling problems. A review of established handling qualities methods showed that they were either unsuitable for aeroelastic aircraft, or had significant disadvantages. After consideration of the basic principles behind a number of handling qualities methods, a new handling qualities method was developed, the Experimental Behavior Measurement Method (EBMM). This new method is based on the principle that a satisfactory match between the aircraft characteristics and the human operator's behavioral characteristics is required to acquire proper vehicle handling qualities. The EBMM requires pilots to perform a number of pitch tracking tasks with a pursuit display, in the aircraft or a moving-base simulator. During these tasks the tracking signal bandwidth is increased, while the pilot's control behavior is determined using system identification techniques. A sudden decrease of the crossover frequency in the pilot's control behavior can be observed when the tracking signal bandwidth exceeds the pilot-vehicle capabilities. This phenomenon is called crossover regression, and the bandwidth at which crossover regression occurs is defined as the crossover-regression frequency. Since the crossover-regression frequency is dependent on the pilot-vehicle capabilities, it can be considered to be a measure of the handling qualities. The validity and applicability of the EBMM were investigated by conducting an experiment in the TU Delft SIMONA flight-simulator. Three aircraft models with varying levels of aeroelasticity were evaluated, using both the new EBMM as well as the well-established Cooper-Harper rating method, which assesses flying qualities as a surrogate for handling qualities. When the effects of the amount of aeroelasticity on the flying and handling qualities were compared, both a quantitative and qualitative correlation was seen between the results of the Cooper-Harper rating method and the new EBMM. In conclusion, the results suggest that the new EBMM method can contribute to the development of improved handling qualities of large and flexible future aircraft aircraft.","Handling Qualities; Aeroelasticity; Cybernetics","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:a0bc538a-c447-44c8-bf56-4a9090211b98","http://resolver.tudelft.nl/uuid:a0bc538a-c447-44c8-bf56-4a9090211b98","Thermoplastic Composite Wind Turbine Blades: An Integrated Design Approach","Joncas, S.","Van Kuik, G.A.M. (promotor); Bersee, H.E.N. (promotor)","2010","This thesis proposes a new structural design concept for future large wind turbine blades based on fully recyclable thermoplastic composites (TPC). With respect to material properties, cost and processing, reactively processed anionic polyamide-6 (APA-6) has been identified as the most promising thermoplastic polymer system for these future wind turbine blades. After mechanically characterizing in situ polymerized APA-6/glass composites and assessing their recyclability, TPC oriented blade designs were developed following an integrated finite-element approach based on topology and size optimization techniques. Results showed that when compared to today’s classic epoxy-based blade design, this TPC oriented design could reduced blade mass by 3% for identical structural performances. Furthermore, due to the presence of ribs in the design, aerodynamic profile and shear web distortion can be significantly reduced.","wind turbine blade; thermoplastic composite; structural optimization; anionic polyamide-6","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Design and Production of Composite Structures","","","",""
"uuid:63881492-9c91-4b92-be6a-d33d1152ac4e","http://resolver.tudelft.nl/uuid:63881492-9c91-4b92-be6a-d33d1152ac4e","Thermoplastic composite wind turbine blades: Vacuum infusion technology for anionic polyamide-6 composites","van Rijswijk, K.","Beukers, A. (promotor); Picken, S.J. (promotor)","2007","Due to the increasing costs of fossil fuels and the improved efficiency of wind turbines in the last decade, wind energy has become increasingly cost-efficient and is well on its way of becoming a mainstream source of energy. To maintain a continuous reduction in costs it is necessary to increase the size of the turbines. For the blades a structural redesign is inevitable and an aircraft-wing-like design consisting of ribs, spars and skins made of thermoplastic composite parts is proposed. Unfortunately, state-of-the-art melt processing of thermoplastic composites requires heavy presses, which makes it impossible to produce large and thick structures like wind turbine blades. As an alternative, this thesis describes the development of reactive processing of thermoplastic composites through vacuum infusion, which is a commonly used technique for manufacturing of thermoset composite wind turbine blades. An anionic polyamide-6 (APA-6) casting resin with water-like viscosity is used to impregnate a stack of ""dry"" glass fiber fabrics, after which in situ polymerization of the semi-crystalline APA-6 matrix takes place within 30 minutes at temperatures around 180°C. The developed technology was successfully applied to infuse 2 to 25 mm thick thermoplastic composites with a fiber volume content of 50%. These APA-6 composites possess outstanding static properties and a promising resistance against fatigue, which is one of the main requirements for wind turbine blade composites. Additional advantages for application in wind energy are the low costs of the resin, the short infusion and curing time, and the fact that APA-6 can be recycled in various ways in an economically sound manner. Increasing the moisture resistance of APA-6 composites is mentioned as most important recommendation for further development.","wind turbine blades; thermoplastic composites; vacuum infusion; anionic polyamide-6; reactive processing","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7966cbb4-14d6-4c0c-8d13-70730a002b8d","http://resolver.tudelft.nl/uuid:7966cbb4-14d6-4c0c-8d13-70730a002b8d","Theory and practice of flutter calculations for systems with many degrees of freedom","Van de Vooren, A.I.","Van der Neut, A. (promotor); Van Veen, S.C. (promotor)","1952","","","nl","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0bb65bac-072a-4d3c-abad-d2143b0b5e96","http://resolver.tudelft.nl/uuid:0bb65bac-072a-4d3c-abad-d2143b0b5e96","Theory on a partially ionized gas centrifuge","Van den Berg, M.S.","Kistemaker, J. (promotor); Steketee, J.A. (promotor)","1982","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Engineering","","","",""
"uuid:080da888-6fc8-41f6-b806-3a7b337bcb77","http://resolver.tudelft.nl/uuid:080da888-6fc8-41f6-b806-3a7b337bcb77","Enhanced conformal mapping method for airfoil design and analysis.","Sardjadi, D.","Van Lingen, J.L. (promotor)","1996","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:860293f4-1a66-4cf2-9cc9-1d2318a6709f","http://resolver.tudelft.nl/uuid:860293f4-1a66-4cf2-9cc9-1d2318a6709f","The Far Side: Lunar Gravimetry into the Third Millenium","Floberghagen, R.","Wakker, K.F. (promotor)","2001","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:13d19d31-fe70-4a79-9887-dd85381913fc","http://resolver.tudelft.nl/uuid:13d19d31-fe70-4a79-9887-dd85381913fc","Computational aerodynamics of ordered vortex flows","Hoeijmakers, H.W.M.","Van Ingen, J.l. (promotor); Wesseling, P. (promotor)","1989","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:17a77d95-c734-4540-aead-50dcb730ad84","http://resolver.tudelft.nl/uuid:17a77d95-c734-4540-aead-50dcb730ad84","Tailoring the Mechanical Properties of Titanium Alloys via Plasticity Induced Transformations","Neelakantan, S.","Van der Zwaag, S. (promotor)","2010","Titanium alloys possess good corrosion properties, high temperature stability and high strength-to-weight ratio. However, they fall short in providing the optimum strength-ductility relation in the most demanding structural applications, including the aerospace sector. Inspired by the possibility of enhancing the strength-ductility relation in steels through the TRIP effect, the thesis elucidates at identifying and quantifying the key factors that effectively control and/or promote such effect (termed here as Plasticity induced Transformation in Titanium alloys (PiTTi)), and exploring the plausible property improvements it may lead in metastable beta titanium alloys. Controlling the key factors that effectively promote such effect through experimentation, and a novel theoretical alloy design methodology lead to new grades of titanium alloys with potential for improved properties.","Titanium alloys,; Ms temperature model,; Alloy design,; Thermodynamics,; Martensitic transformation,; Metastable beta alloys,; Mechanical properties","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Materials and Manufacturing / Novel Aerospace Materials group","","","",""
"uuid:6bc0134a-0715-4829-903d-6479c5735913","http://resolver.tudelft.nl/uuid:6bc0134a-0715-4829-903d-6479c5735913","Global Nonlinear Model Identification with Multivariate Splines","De Visser, C.C.","Mulder, J.A. (promotor)","2011","At present, model based control systems play an essential role in many aspects of modern society. Application areas of model based control systems range from food processing to medical imaging, and from process control in oil refineries to the flight control systems of modern aircraft. Central to a model based control system is a mathematical model of the physical system or process that is being controlled. The field of science concerned with the identification of models of physical systems is called system identification. In this thesis, a new methodology is proposed for the identification of models of nonlinear systems using multivariate simplex splines. This new methodology has the potential to increase the performance of any model based control system by improving the quality of system models. Multivariate simplex splines consist of polynomial basis functions, called B-form polynomials, which are defined on geometric structures called simplices. Every simplex supports a single B-form polynomial which itself consists of a linear combination of Bernstein basis polynomials. Each individual Bernstein basis polynomial is scaled by a single coefficient called a B-coefficient. The B-coefficients have a special property in the sense that they have a unique spatial location inside their supporting simplex. This spatial structure, also known as the B-net, provides a number of unique capabilities that add to the desirability of the simplex splines as a tool for data approximation. For example, the B-net simplifies local model modification by directly relating specific model regions to subsets of B-coefficients involved in shaping the model in those regions. This particular capability has the potential to play an important role in future adaptive model based control systems. In such a control system, an on-board simplex spline model can be locally adapted in real time to reflect changes in system dynamics. The approximation power of the multivariate simplex splines can be increased by joining any number of simplices together into a geometric structure called a triangulation. Triangulations come in many shapes and sizes, ranging from configurations consisting of just two simplices to configurations containing millions of simplices. Triangulations can be optimized by locally increasing or decreasing the density of simplices to reflect local system complexity. The new methodology was applied in the identification of a complete set of aerodynamic models for the Cessna Citation II laboratory using flight data obtained during seven test flights. In total, 247 flight test maneuvers were flown which together provided a significant coverage of the flight envelope of the Citation II. The complete identification dataset consisted of millions of measurements on more than sixty flight parameters. More than 2000 prototype spline based aerodynamic models were identified using a newly developed, highly optimized software implementation of the simplex spline identification algorithm. Using the developed methods for simplex spline model validation it was proved that the models are both accurate and of guaranteed numerical stability inside the spline domain. The identification and validation results of the simplex spline models were compared with those of ordinary polynomial models identified using standard identification methods. These results showed that the multivariate simplex spline based aerodynamic models were of significantly higher quality than the aerodynamic models based on ordinary polynomials.","Multivariate Splines; Bernstein Polynomials; System Identification; Parameter Estimation; Aerodynamic Model Identification; Flight Testing; Triangulations","en","doctoral thesis","C.C. de Visser","","","","","","","2011-07-04","Aerospace Engineering","Control & Operations","","","",""
"uuid:c5ac8599-fca2-40eb-adc6-bbfeeec38fab","http://resolver.tudelft.nl/uuid:c5ac8599-fca2-40eb-adc6-bbfeeec38fab","Orbit determination of satellite formations","Van Barneveld, P.W.L.","Ambrosius, B.A.C. (promotor); Visser, P.N.A.M. (promotor)","2012","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:6f647fd6-7cda-4351-b9e2-701b560055e1","http://resolver.tudelft.nl/uuid:6f647fd6-7cda-4351-b9e2-701b560055e1","Prediction of a tail downwash, ground effect and minimum unstick speed of jet transport aircraft","Slingerland, R.","Torenbeek, E. (promotor)","2005","A design tool has been developed to estimate the horizontal tail size of a jet transport aircraft during the preliminary design phase with regard to the minimum unstick requirement. The ground effect has been modelled analytically using lifting line theory. The minimum unstick manoeuvre has been simulated numerically and is embedded in the automated design tool. That tool is validated extensively against experimental data and appears to be sufficiently accurate. In addition, it improves the prediction of the take-off field length.","aerodynamics; take-off simulation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a528e343-86d6-4d6b-8f6d-99384dce0fc5","http://resolver.tudelft.nl/uuid:a528e343-86d6-4d6b-8f6d-99384dce0fc5","Elements of automated aeroelastic analysis in aircraft preliminary design","Lisandrin, P.","van Tooren, M.J.L. (promotor); Beukers, A. (promotor)","2007","","aeroelasticity; finite elements; P-elements; modal analysis; computational fluid dynamics","en","doctoral thesis","","","","","","","","","Aerospace Engineering","System Engineering & Aircraft Design","","","",""
"uuid:32601cee-c83d-471f-a849-bf2f1786ad25","http://resolver.tudelft.nl/uuid:32601cee-c83d-471f-a849-bf2f1786ad25","Diaphragm forming of continuous fibre reinforced thermoplastics. Process analysis and development.","Bersee, H.E.N.","De Jong, Th. (promotor)","1996","","composietmaterialen; thermovormen; vezelversterkte kunststoffen; productietechnieken","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:abb30ba0-5307-4592-aa4f-6016c0cd85f8","http://resolver.tudelft.nl/uuid:abb30ba0-5307-4592-aa4f-6016c0cd85f8","Space systems conceptual design: Analysis methods for engineering-team support","Ridolfi, G.","Ambrosius, B.A.C. (promotor)","2013","The research can be placed in the framework of designing methods for complex systems focused on the conceptual design phase of the systems’ life-cycle. More specifically, the methods presented in the dissertation belong to the category of Operational Research methods. They aim at the creation of design and analysis tools in support of the engineering team during conceptual design activities. Even though the proposed methods are referred to space-systems applications throughout the dissertation, they are easily extendable also to other engineering applications. This aspect makes the research of great theoretical and practical interest also outside the aerospace industry. A powerful methodology was developed that is typical of more specialist applications (for more detailed design phases) and that is flexible and fast to execute at the same time as required for a conceptual design phase of a complex system.","Conceptual Design; Sensitivity Analysis; Robust Optimization; Concurrent Design; Space Systems Models","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Space Engineering - Astrodynamics and Space Missions","","","",""
"uuid:cad92d3e-b8e3-48ed-a23e-e0fecd2a8133","http://resolver.tudelft.nl/uuid:cad92d3e-b8e3-48ed-a23e-e0fecd2a8133","Experimental investigation of re-entry aerodynamic phenomena - Development of non-intrusive ?ow diagnostics in a Ludwieg tube","Schrijer, F.F.J.","Scarano, F. (promotor)","2010","To further improve the design of hypersonic vehicles so that fully reusable systems become a reality, the detailed understanding of the ?ow ?eld that the vehicle generates is of paramount importance. The thesis deals with the aspects of experimental ?ow research which includes also the ?ow facility and the measurement techniques. First a description is given of the investigation and assessment of the Hypersonic Test Facility Delft (HTFD), which is the facility used in the experiments. Thereafter two measurement techniques, particle image velocimetry (PIV) and quantitative infrared thermography (QIRT) are introduced that enable to obtain high quality measurement data of the hypersonic ?ow ?eld generated by the HTFD. In the remainder of the thesis two important ?ow phenomena, shock wave boundary layer interaction and boundary layer transition, have been investigated using PIV and QIRT that are of great importance for re-entry vehicles.","re-entry; hypersonic flow; wind tunnel; particle image velocimetry; quantitative infrared thermography; boundary layer transition; shock wave boundary layer interaction","en","doctoral thesis","Proefschriftenmaken.nl","","","","","","","2010-01-22","Aerospace Engineering","Aerodynamics","","","",""
"uuid:879829f9-73d2-4008-82c5-dbb5c2b6a4a6","http://resolver.tudelft.nl/uuid:879829f9-73d2-4008-82c5-dbb5c2b6a4a6","Damage and Failure of Non-Conventional Composite Laminates","Lopes, C.S.","Gürdal, Z. (promotor); Camanho, P.P. (promotor)","2009","For a long time, the application of composite materials was restricted to military aircraft and secondary structures of commercial aircraft. Furthermore, the design possibilities offered by composite laminates were narrowed to quasi-isotropic configurations due to their closer behaviour with monolithic materials, hence with a more predictable response, and easiness of manufacturing. However, this picture is changing. Nowadays, there are automated systems capable of rapidly manufacturing large and high quality composite parts. As an example, the fuselage of the all-new long haul Boeing 787 aircraft is being built by means of automated fibre-placement machines. These highly precise systems can build laminates made of combinations of ply angles other than the conventional 0 degrees, 90 degrees and 45 degrees. Furthermore, automated fibre-placement machines can steer the fibres tows as these are being placed, resulting in plies with variable fibre orientation and laminates whose elastic properties vary along their planar coordinates, termed “variable-stiffness panels”. In this thesis, the expression “non-conventional composite laminates” refers to straight-fibre laminates made of combinations of non-conventional ply angles as well as to variable-stiffness panels. The structural behaviour of these non-conventional composites is not fully understood yet, particularly their damage and failure responses. The goal of this thesis is to shed light on this field.","Automated Fibre Placement; Variable-Stiffness Panels; Failure Criteria; Progressive Failure Analyses; Impact Damage; Damage Tolerance","en","doctoral thesis","TU Delft, Faculteit Luchtvaart- en Ruimtevaarttechniek","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:cd5f72f5-3005-46c9-971d-d9f7c10268cc","http://resolver.tudelft.nl/uuid:cd5f72f5-3005-46c9-971d-d9f7c10268cc","Fatigue of woven thermoplastic composites: The effect of the fibre-matrix interface","Rasool, S.","Benedictus, R. (promotor); Bersee, H.E.N. (promotor)","2015","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","SI&C","","","",""
"uuid:240c652a-bfd7-4bab-b6fd-4d2ccab3db29","http://resolver.tudelft.nl/uuid:240c652a-bfd7-4bab-b6fd-4d2ccab3db29","Fatigue Crack and Delamination Growth in Fibre Metal Laminates under Variable Amplitude Loading","Khan, S.","Benedictus, R. (promotor)","2013","This thesis presents the investigation into the fatigue propagation and delamination growth of Fibre Metal Laminates under variable amplitude loading. As explained in the first chapter, the motivation of the research is twofold: first, to obtain a clear understanding and detailed characterization of the failure mechanisms in GLARE under variable amplitude loading (selective and flight load spectra). Second is to obtain an accurate prediction model for fatigue crack propagation in GLARE accounting for fibre bridging, delamination and influence of plasticity. The major concept in this thesis is that the stress intensity at the crack tip in the metal layers of a Fibre Metal Laminates (FMLs) is the factor determining the extension of that crack under cyclic loading. This implies that the stress intensity factor can be described with Linear Elastic Fracture Mechanics, including the contribution of the fibre layers and the with the crack growth associated delamination behaviour. The investigation presented in this thesis, covers the theoretical analysis of the crack growth phenomena and experiments to support and validate the developed prediction model. This investigation has been restricted to through-the-thickness cracks with the same crack length in all metal layers. In the second chapter, the various GLARE grades and lay-ups are defined together with a description of the manufacturing process, quality assurance procedures and fatigue crack growth phenomena. The aspects introduced are the fatigue crack growth in the aluminium layers, controlled by the stress intensity factor at the crack tip, and the delamination of the aluminium and prepreg layers, which occurs in the wake of the propagating crack. The crack opening is constrained by the bridging fibre layers, while the stress redistribution to these fibre layers determines the delamination growth. In addition, this chapter discusses the effects of variable amplitude loading in metals, together with the models developed so far to predict fatigue crack growth. The influence of variable amplitude loading on the delamination growth (i.e. a major phenomenon contributing to the slow fatigue crack growth in FMLs) is discussed in chapter 3. An extensive test programme is presented in this chapter utilizing double and multiple block loads, and flight load spectra to validate the hypothesis that delamination in FMLs is independent of retardation effects under variable amplitude loading. Furthermore, the use of scanning electronic microscopy is presented to study the delamination growth striations on the disbonded fracture surfaces. Chapter 4 presents the effect of variable amplitude loading on delamination shapes. These delamination shapes influence the bridging stresses and the crack tip stress intensity factor. The change in the delamination shape due to variable amplitude loading is understood, and the hypothesis on the reason of this change in delamination shapes has been validated. The use of Digital Image Correlation (DIC) is presented to observe delamination shapes and crack tip plastic zones in-situ fatigue testing. Although a change in delamination shape can be observed, its effect on the bridging stress profile is observed to be negligible. Crack tip plasticity and shear-lip formation both were investigated, as presented in chapter 5. Difference in shear-lip morphology was observed in monolithic metals, adhesively bonded metal laminates and FMLs. Monolithic metals revealed typical shear-lip profiles with the early tensile mode followed by a transition mode and finally the transverse shear mode. For metal laminates (without fibres), the mode transition happened quite late during fatigue crack growth, but the transition length was smaller than those of monolithic metals. In FMLs the shear lip profiles were rather difficult to see with the naked eye or optical microscope. However, the straight appearance of the crack when observed from the specimen side, implied a flat cracked fracture surface without shear lips. Plastic zone sizes are compared in the same chapter. In case of monolithic metals and metal laminates, a big difference is observed between the predicted plastic zone sizes (using Irwin’s relation) and the sizes measured with DIC. However, comparing these sizes for FMLs revealed only a small difference. In FMLs, the plastic zone sizes are observed to be independent of the crack length which corresponds to the constant crack tip stress intensity factors. Chapter 6 presents the development and validation of three different types of prediction models. These models include a linear damage accumulation (non-retardation) model, a yield zone model and a crack closure model. The predictions using these models correlated with experimentally observed crack growth behaviour. Chapter 7 outlines the sub-routine added to the prediction model for post-stretched laminates. This routine has been validated with the data from post-stretched GLARE 1 and ARALL from the literature. Chapter 8 summarizes the conclusions of the investigation. It can be concluded that with the proposed prediction model, the mechanism of crack propagation and delamination growth in GLARE is fully described and understood. The prediction model has been validated with experimental crack growth data, and is considered accurate. In its implemented form, the model has the potential to be extended to other material-, geometrical- and test parameters.","Fibre Metal Laminates; Variable Amplitude Loading; Fatigue Crack Growth; Delamination Growth; Plastic Zone","en","doctoral thesis","Uitgeverij BOXPress","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:77f36876-b0d4-4a35-a9b5-7bac8c5572c5","http://resolver.tudelft.nl/uuid:77f36876-b0d4-4a35-a9b5-7bac8c5572c5","Kinetics of the β-AlFeSi to α-Al(FeMn)Si transformation in Al-Mg-Si alloys","Kuijpers, N.C.W.","Van der Zwaag, S. (promotor)","2004","Among all the process steps of the production of aluminium extrusion products, the homogenisation of Al-Mg-Si aluminium billets is a very important one, since it gives significant changes in the microstructure of the alloy, leading to an improved extrudability of the material and improved properties of the final extruded product. During this homogenisation process the aluminium billets are annealed in a furnace for a few hours at a temperature of approximately 585 °C. One important microstructural change during homogenisation is the transformation of plate-like intermetallic β-Al5FeSi particles into a string of separate coarse α-Al(FeMn)Si type of intermetallic particles. This β-to-α phase transformation considerably improves the extrusion process since the transformed α-particles in the homogenised material improve the ductility of the material and the surface quality of the extruded material. A better understanding of the β-to-α transformation kinetics is important, since this gives more insight into the effects of process parameters of the homogenisation such as temperature, homogenisation time, as-cast microstructure and chemical composition. It is the objective of this research to characterise the β-to-α transformation kinetics in Al-Mg-Si alloys (6xxx alloys) by experiments (such as optical microscopy, SEM and XRD) and to develop a physical model (FEM) that describes this transformation. Further, the research aims at gaining more insight into the behaviour of intermetallic phases during thermal processing.","aluminium; homogenisation; intermetallics; transformation; model","en","doctoral thesis","Van Gerwen B.V.","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3affd8eb-8fbd-40da-aefc-48a96efe8afb","http://resolver.tudelft.nl/uuid:3affd8eb-8fbd-40da-aefc-48a96efe8afb","Finite element based reduction methods for static and dynamic analysis of thin-walled structures","Tiso, P.","Gürdal, Z. (promotor)","2006","Abstract not available","Nonlinearity; Finite Elements; Reduction; Thin-walled Structures.","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3d2c76dc-0335-44d6-a835-64eb5b7d7271","http://resolver.tudelft.nl/uuid:3d2c76dc-0335-44d6-a835-64eb5b7d7271","Large-eddy simulation of cumulus convection","Cuijpers, J.W.M.","Nieuwstadt, F.T.M. (promotor); Oerlemans, J. (promotor)","1994","","meteorologie; stromingsleer","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:57f0cea4-4e05-47bf-8f53-fb1d6e36d39f","http://resolver.tudelft.nl/uuid:57f0cea4-4e05-47bf-8f53-fb1d6e36d39f","Wind turbine aerodynamics in yaw: Unravelling the measured rotor wake","Haans, W.","Van Bussel, G.J.W. (promotor); Van Kuik, G.A.M. (promotor)","2011","","wind turbine aerodynamics; vortex wake model; wind tunnel; rotor experiment; yaw; airfoil model; wake model; experimental aerodynamics; rotor momentum model; hot wire anemometry; flow visualization; strain gauge; tuft visualization; Blade Element Momentum model; BEM; BEM validation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","wind energy","","","",""
"uuid:b6ebc3ae-8068-4552-8970-80a5282ed31d","http://resolver.tudelft.nl/uuid:b6ebc3ae-8068-4552-8970-80a5282ed31d","Analysis of the fatigue phenomenon in aluminium alloys","Schijve, J.","Jongenburger, P. (promotor)","1964","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c147ae5f-f114-4ffa-89f7-a61bf379a028","http://resolver.tudelft.nl/uuid:c147ae5f-f114-4ffa-89f7-a61bf379a028","Software-Enabled Modular Instrumentation Systems","Soijer, M.W.","Mulder, J.A. (promotor)","2003","Like most other types of instrumentation systems, flight test instrumentation is not produced in series; its development is a one-time achievement by a test department. With the introduction of powerful digital computers, instrumentation systems have included data analysis tasks that were previously limited to post-experiment processing. However, the resulting integrated systems are hard to maintain in the traditional environment of instrumentation development. Software-Enabled Modular Instrumentation Systems describes the theory and praxis of a new methodology to analyze, design, implement, and validate a digital signal processing system for test and evaluation applications in the information age. Based on life cycle concepts from software engineering, this dissertation presents an object-oriented approach that allows to combine proprietary and off-the-shelf components in a way that reusability of the elements and extensibility of the application are ensured. The methodology covers all phases of test and evaluation: desktop simulation, hardware- and pilot-in-the-loop simulation, flight test, and post-experiment data analysis. Moreover, optimum reusability of the components is ensured not only through the phases of the project, but also from one test program to the next. The methodology thus results in reduced system development time and cost, and improved system reliability.","flight test; design; instrumentation; real-time","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4e195849-ba26-4b4f-8f92-ccfa85af7a3b","http://resolver.tudelft.nl/uuid:4e195849-ba26-4b4f-8f92-ccfa85af7a3b","Damage Tolerant Repair Techniques for Pressurized Aircraft Fuselages","Fredell, R.S.","Schijve, J. (promotor); Vogelesang, L.B. (promotor)","1994","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:41384c73-f7de-4580-838c-8f0210908ac5","http://resolver.tudelft.nl/uuid:41384c73-f7de-4580-838c-8f0210908ac5","Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders","De Kanter, J.L.C.G.","Gürdal, Z. (promotor); Van der Zwaag, S. (promotor)","2006","Summary accompanying the thesis: Energy Absorption of Monolithic and Fibre Reinforced Aluminium Cylinders by Jens de Kanter This thesis presents the investigation of the crush behaviour of both monolithic aluminium cylinders and externally fibre reinforced aluminium cylinders. The research is based on analytical work, numerical work and experimental work, which together show a complete picture of the tube axial crush phenomenon. The research is relevant for transport safety. In specific for the automotive industry, however with a clear link to the aerospace industry, based on the materials used and current developments in aerospace crashworthiness. Materials used in the investigation are aluminium and fibre composite, both materials extensively used in the aerospace industry. Also the aerospace safety focus is widening nowadays. Where in the past only crash prevention was considered now also crash protection is of concern. Transport safety and also sustainability benefit from reduced mass of the vehicles. In case of crash structures, the mass can be reduced by having components with a higher specific energy absorption (energy absorbed per unit mass, SEA) . Further quantitative requirements for energy absorbing tubes are the load ratio, i.e. the peak load divided by the mean load and the stroke efficiency, i.e. the axial displacement divided by the original tube length. Qualitative requirements for the tubes are for example reliability, predictability and post-crash integrity. In search of improved crash tube performance this research followed a trajectory where aluminium tubes are reinforced by fibre composite. In order to gain full insight in the crush phenomena, first the monolithic aluminium tube crush behaviour is described. The aluminium crush behaviour is governed by a number of collapse modes, which depend on the diameter to thickness ratio of the tubes. Basically two collapse modes exist, the axisymmetric or concertina collapse mode and the diamond mode. The diamond collapse mode is characterised by the number of diamond lobes present. For tubes with diameter over thickness ratios in the range of 10 to 100 the number of diamond lobes may vary from two to four. Most of the tubes tested were made of aluminium alloy 6060-T66, with a diameter of 50 mm and thickness varying from 0.5 mm to 2.5 mm. Within this thickness range the folding takes place in the plastic regime of the material. The experimentally established folding behaviour is well reproduced by analyses with a number of different finite element codes. Abaqus implicit was used for the static simulation and both Abaqus explicit and PAM-CRASH were used for the dynamic situation. The dynamic tube crushing is characterised by a dynamic buckling phenomenon and a small increase of the loads compared to the static situation. The load increase is attributed to the strain rate sensitivity of the metal and due to inertia (of the laterally moving fold elements) . Also analytical models are presented for the metal tube crushing. These give good predictions of the mean loads and show the balance in the energy absorption between membrane stretching and fold bending. Shortcoming of the models is the validity over different collapse modes. For improving the SEA, the aluminium cylinders were reinforced by externally winding impregnated S2 glass fibres. A few tubes were reinforced by carbon fibres and some were reinforced with prepreg in the tube longitudinal direction as well. The fibre winding orientation and lay-up were varied in the experimental program. In the production process some minor variables, as used adhesive and fibre winding tension were examined. The adhesive was used between the aluminium tube and the fibre windings and had a beneficial effect on the energy absorption. The hoop winding reinforcements un-balance the stiffness distribution in the monolithic tube, giving high restoring membrane stresses in circumferential direction, which increase the buckling load and change the folding pattern from a concertina mode to diamond 3 lobe and 2 lobe. The relative increase in SEA is largest (about 20% ) for the single layer reinforcement, with a concertina collapse mode. The thick reinforcements ( 6 or more layers) caused 2 lobe folding, which has a large fold length and a relatively low SEA, making this configuration less efficient. By changing the orientation of the fibres different collapse modes may be initiated. The experimental program includes the hoop wound specimen (90) , hoop wound specimen with UD fibres in longitudinal tube direction (0 degrees/90 degrees) , helix wound specimen (plusminus 0 degrees) , and helix hoop wound specimen (plusminus 0 degrees /90 degrees) . The character of the collapse mode varied from global two lobe folding to small three and four lobe folding. The smaller the folds the higher the mean load and energy absorption. The balanced lay-up of the helix hoop wound specimen (plusminus 45 degrees/90 degrees ) proved best in energy absorbing performance. The SEA of the monolithic metal tube was increased by 65% , while the load ratio reduced from 2.0 to 1.5. The post crash integrity was diminished however as also cracks were present in the metal.","crashworthiness; axial compression; crushing; multi-material tubes; specific energy absorption","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:575b510c-8894-4dfb-96d3-521be883580e","http://resolver.tudelft.nl/uuid:575b510c-8894-4dfb-96d3-521be883580e","Vortex flow and Vortex breakdown above delta wing in high subsonic flow","Donohoe, S.R.","Bakker, P.G. (promotor)","1996","","aerodynamics; delta wing; vortex flow; flow visualization; schlieren; vortex breakdown; tansonic flow; wind tunnel testing; five-holve probe","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ef473d71-e384-4f2f-b9c2-881eb2fb9918","http://resolver.tudelft.nl/uuid:ef473d71-e384-4f2f-b9c2-881eb2fb9918","AIDA. Artificial Intelligence supported conceptual Design of Aircraft","Rentema, D.W.E.","Jansen, F.W. (promotor); Torenbeek, E. (promotor)","2004","This thesis describes the development of a computer support tool that supports the initial, conceptual design process. In this first design phase one or more concepts are defined which are assumed to be able to comply with the design specifications. These concepts can be elaborated in more detail with the aid of the conventional CAD tools that have been developed in the last decades and are currently widely available. Due to the non-deterministic character of conceptual design, however, such conventional computer techniques are inadequate to support this phase. Therefore the use of Artificial Intelligence techniques has been investigated in this project. The initial application was chosen in the area of aircraft design, because of its complexity. The tool and methodology are, however, also applicable to support the design of ships, buildings and industrial appliances. The developed design tool and methodology is based on the well-known ""design cycle"", which in our version consists of four steps: 1. Suggesting a concept: this task is supported with Case-Based Reasoning (CBR) techniques. From a case-base that is filled with data of existing artefacts, one artefact is selected whose performances best match the design specifications. This case is used as a starting point and delivers the configuration or topology of the design, and the initial parameter settings. Possibly two or more cases can be combined, resulting in an adapted case. 2. Simulating the artefact's performances: this task is supported with Rule-Based Reasoning (RBR) and Geometric Modelling (GM) techniques. With the rules representing the domain knowledge in an explicit, algebraic format, a network of rules and relations is built that relates the sizing parameters with performance parameters. GM is used to build a geometric model and to handle the geometric constraints. 3. Evaluating these performances: using the RBR network of relations and the GM constraints, the related solvers allow quickly and easy changing of parameter values to modify the design. 4. Proposing modifications: the design tool does not support this task explicitly. However, as is mentioned in step 1, a first modification of the case's topology (adaptation) is supported with CBR. Then the cycle is repeated until the design concept is satisfactory and can be used as input for further elaboration and evaluation with existing CAD/CAE tools. Each of these three techniques, CBR, RBR and GM, has been implemented in a separate module. Existing programs have been used and adapted for this study. To test the set-up and viability of the design tool, a case-study has been performed, concerning the conceptual design of an 80 passenger commercial aircraft. The study has proven that the design approach is useful for ""configuration design"" type of design tasks, but is less suitable for innovative and creative design. Although each technique has shown to be suitable for its task, there are also some difficulties. For example, each technique requires substantial effort in the preprocessing phase, when filling the data or knowledge bases. And experience is needed to operate the CBR and RBR modules properly. Many apparently minor practical issues can have a serious effect on the efficiency of the techniques. Issues which need much attention in following development studies are case adaptation and integration of the three applied techniques.","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d234da69-8daa-4dfe-89da-773e09ad5086","http://resolver.tudelft.nl/uuid:d234da69-8daa-4dfe-89da-773e09ad5086","Theoretical and experimental investigations of incompressible laminar boundary layers with and without suction","Van Ingen, J.L.","Steketee, J.A. (promotor); Van der Maas, H.J. (promotor)","1965","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:76d57853-a2cf-4361-92d8-04740c3c530d","http://resolver.tudelft.nl/uuid:76d57853-a2cf-4361-92d8-04740c3c530d","Identification of Turboprop Thrust from Flight Test Data","Muhammad, H.","Mulder, J.A. (promotor); Gerlach, O.H. (promotor)","1995","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:89455d9a-fb38-42bf-b1db-03a8a5104bcf","http://resolver.tudelft.nl/uuid:89455d9a-fb38-42bf-b1db-03a8a5104bcf","Model and Sensor Based Nonlinear Adaptive Flight Control with Online System Identification","Sun, L.G.","Mulder, M. (promotor); Chu, Q.P. (promotor)","2014","Consensus exists that many loss-of-control (LOC) in flight accidents caused by severe aircraft damage or system failure could be prevented if flight performance could be recovered using the valid and remaining control authorities. However, the safe maneuverability of a post-failure aircraft will inevitably be reduced due to the malfunction. Non-conventional control strategies which rely on modern control techniques and computational power are essential to control systems in post-failure flight conditions to extract the most from the reduced, remaining aircraft control authorities and restore the flight performance of an aircraft or achieve a safe landing. One such non-conventional control strategy is called active fault tolerant flight control (FTFC), which is designed to detect changes in an aircraft's dynamics caused by structural, actuator, or sensor failure and accommodate the damage or failure using an adaptive reconfiguration mechanism. The active FTFC technique is able to deal with unanticipated and multiple simultaneous failures. The overall architecture of an active FTFC system ideally should consist of a fault detection and diagnosis (FDD) module, a state reconstruction unit, a reconfigurable control component, a control allocation unit and a flight envelope protection (FEP) unit. Generally speaking, FTFC systems can be classified into two types: model-based FTFC systems and model-free FTFC systems, according to whether any of the system's components require an aerodynamic model at their core or not. A model-based FTFC system contains an aerodynamic model identification (AMI) module, which supplies an accurate aircraft model to an indirect adaptive nonlinear controller in the reconfigurable control block, to a dynamic flight envelope determination algorithm in an FEP unit, or to an FDD unit. An aerodynamic model identification approach using a physical, interpretable modeling structure can detect and even quantify structural failures occurring in the aircraft structure or one of the control surfaces by monitoring changes in stability derivatives and control derivatives. There are many candidate control approaches which can achieve reconfiguration when designing a reconfigurable flight controller. These reconfigurable control methods may rely on many different reconfiguration mechanisms ranging from switching, model following, matching to adaptive compensation. These methods include nonlinear adaptive control which achieves reconfiguration through compensation, and this method is receiving increasing attention in the flight control aerospace research community. Nonlinear adaptive control is divided into direct adaptive control and indirect adaptive control, the difference is that the latter requires an online system model. Indirect adaptive control is also called model-based or modular adaptive control, which has some advantages over the direct adaptive control and other model-free control methods. One advantage is that a modular control approach has the potential to yield a more efficient controller which requires less control effort. Such an efficient controller can be achieved by maintaining useful damping terms of an identified system model in the closed-loop system. This is attributed to the good properties of many control design techniques such as backstepping such that the dynamics of an original system can be chosen to be canceled or maintained during a controller design process. Modular adaptive control also has an inherited shortcoming, it can only guarantee input-to-state stability, i.e. modular adaptive control cannot guarantee the stability of the overall closed-loop system because its stability proof relies on the certainty equivalence principle. The weakness of the certainty equivalence principle, i.e., convergence problem of the model parameters, can be improved by enhancing model accuracy or reliability, to do this, it becomes critical to develop advanced, powerful aerodynamic model identification approaches capable of capturing changes in flight dynamics either during a high maneuvering flight mission or a post-failure condition. Flight envelope protection is a necessary technique that should be applied by controller designers to prevent LOC incidents, taking into account highly maneuvering flight tasks and/or highly perturbed flight conditions due to the ongoing failure. An FEP component should provide a pilot with a safe flight envelope and pose constraints on the reference commands fed to an internal controller to make the commands achievable. An aerodynamic model that is valid over an entire flight envelope plays a crucial role in full-envelope modular adaptive control and flight envelope protection. A globally valid model is required for modular adaptive control to enable the designed controller to work properly in a large operating range. Once estimated, the global model in a model-based adaptive control method can be stored for later re-use when the same flight condition is revisited. Except being needed by a model-based controller, an accurate aerodynamic model is also required for flight envelope protection. Naturally, the estimated aerodynamic model has to be valid for the current aircraft configuration over the entire flight envelope to enable an evolution algorithm to estimate the boundary of the safe flight envelope for the current flight condition. However, only a limited number of model identification approaches are suited for estimating a globally valid aerodynamic model, and each existing possible candidate has variant shortcomings or limitations which make it hard to apply directly to identify an aircraft model. For example, neural networks usually yield a nontransparent model structure which is hard to interpret using physical knowledge of the system, and they commonly encounter a convergence problem. Most kernel methods fall into the nonparametric type of methods, which by nature need as many kernels as the data points under evaluation. It should be kept in mind that only equation-error type model identification methods were investigated in the work reported here. The assumption was made that a sufficiently accurate estimation of aircraft states was available. An alternate method to the modular adaptive reconfigurable control approach is the acceleration measurements-based incremental nonlinear control (AMINC) method. An accurate estimation of an aircraft is hard to achieve during a high maneuvering moment or at a transient period when the flight performance is highly perturbed due to aircraft failure. Incremental nonlinear controllers such as incremental nonlinear dynamic inversion (INDI), incremental backstepping (IBKS) and sensor-based backstepping (SBB) are suited for reconfigurable flight control designs in the sense that they do not require complete aircraft model knowledge. The main research question for the research presented here was: How can an advanced fault-tolerant flight control system be designed to increase the survivability of an aircraft? This led to two subsidiary questions: (1). How can the candidate function approximation methods, i.e. multivariate simplex B-splines and kernel methods, be improved in terms of approximation accuracy and computational efficiency, to meet the need of model-based adaptive control and online flight envelope protection? (2). What are the benefits of using an acceleration measurements-based control approach, i.e., the sensor based backstepping, as an alternative to a model-based adaptive control approach, when designing a reconfigurable flight controller to deal with aircraft failures in a generic fault-tolerant flight control (FTFC) system? With regard to reconfigurable control, the identified model should enable the controller to achieve active reconfiguration and restore the control performance. To answer these questions, four different global model identification methods and two nonlinear incremental adaptive controllers were developed. Two model identification methods use a parametric model structure namely standard multivariate simplex B-splines. The focus was placed on how to achieve fast parameter estimation during the research process for these two methods. In the third identification method, a new model structure called tensor-product simplex B-splines was extended from a single dimension case to a multidimensional case, with a focus on demonstrating the advantage of this new compound model structure in terms of the flexibility in model structure selection, computational efficiency and approximation power. The fourth method uses a kernel type model structure which is also parametric. The new recursive kernel approach was developed by combining a classical recursive kernel method with a novel support vector regression approach. A model identification method using standard multivariate simplex B-splines has many advantages, it can avoid the over-fitting problem which occurs with an ordinary polynomial method using a triangulation technique. The approximation power of a simplex B-spline based method is determined by the per-simplex polynomial order and smoothness order, and can be increased by increasing the density of the subdomains in a triangulation. This simplex B-spline based function approximation method guarantees that its output is bounded by the maximum and minimum B-coefficients, this facilitates its certification for future real life applications. The linear regression formulation of the simplex B-spline based method allows for applying most of the constrained recursive parameter estimation methods. Furthermore, the simplex B-spline based method has a sparse property, which can lead to high computational efficiency by adopting distributed computation or other modern computing techniques. However, a simplex B-spline method can easily yield a large amount of unknown parameters if the function dimension exceeds 4, which results in a high computational load considering the smoothness maintaining and covariance matrix updating. To enhance the computational efficiency of the model identification methods using simplex B-splines, two recursive linear-regression model identification methods were developed in this thesis: a substitution-based multivariate simplex B-spline (SB-MVSB) method and a recursive sequential multivariate simplex B-spline (RS-MVSB) method. In the SB-MVSB method, an efficient recursive solver is developed for a constrained linear regression problem when using simplex B-splines. The constrained linear regression problem is converted into a constraint-free linear regression problem using a general solution for the equality constraints. This transformation was shown to reduce the scale of the identification problem in terms of the number of unknown parameters, and thus the computational load required for the model identification method can be reduced. The RS-MVSB method consists of two consecutive procedures at one model evolution step. The first procedure achieves updating of a local model covering the current data point instead of a global model. The requirement of updating a complete covariance matrix is avoided by only updating one local model, and therefore the computational efficiency of this method is greatly enhanced. The second procedure guarantees a smooth transition between this local model and its neighboring local models. The computational complexity of SB-MVSB and RS-MVSB was given from a mathematician point of view, then, they were validated using simulated flight test data generated using a high-fidelity nonlinear model of an F-16 aircraft. Simulation results showed that both methods can achieve higher approximation accuracy than ordinary polynomial based methods, and both can be many, e.g. 10, times faster than an equality constraint recursive least squares based MVSB (ECRLS-MVSB) method. The second feature of these two methods facilitates their future onboard applications. Tensor-product simplex (TPS) B-splines provide a compound structure, which provide more flexibility than a standard simplex B-spline model during model structure selection. Using TPS B-splines, different dimension of inputs can be treated differently depending on their characteristics determined from a priori knowledge. In the work presented in this thesis, the TPS B-spline concept was extended from a single dimension case into a more general multidimensional case. Compared to standard simplex B-splines, TPS B-splines can make better use of a priori model knowledge. By reducing many unnecessary basis polynomials from the regression vector, TPS B-splines have the potential to lead to a lower computational load than standard simplex B-splines. The TPS B-spline method was validated using a data set generated from a high-fidelity nonlinear F-16 model. Simulation results showed that TPS B-splines can yield higher approximation power than standard simplex B-splines with less B-coefficients. Two similar recursive parametric kernel methods namely weight varying least squares support vector regression (WV-LSSVR) and Gaussian process kernel based LSSVR (GPK-LSSVR) were developed for aerodynamic model identification in this thesis. The focus of this work was enhancing the approximation power of a recursive parametric kernel method by choosing an optimal set of kernels for the kernel scheme. An offline method called improved recursive reduced LSSVR (IRR-LSSVR) was used to determine optimal kernels for a classical recursive kernel method. The new kernel method was validated using a series of public available benchmark data sets well known to researchers from the field of pattern recognition. GPK-LSSVR showed a higher approximation power than WV-LSSVR, and both of them showed a higher approximation power than a classical recursive kernel method based on k-means clustering. A novel type of acceleration measurements-based incremental flight control laws was investigated with the aim of providing a reconfigurable control unit with a powerful non-conventional flight control approach which could accommodate sudden structural or actuator failures occurring in an aircraft. The preferred model-free, incremental control approach used in this thesis was the SBB approach, which was initially developed for control designs of nonlinear nonaffine-in-control systems. The SBB approach achieves an accurate reference command tracking performance by approximate dynamic inversion. The SBB approach was extended to deal with sudden model changes in an aircraft caused by structural or actuator failures. A hybrid two-loop angular controller and a joint two-loop angular controller were designed for the RECOVER model. In the hybrid two-loop angular controller, the angular control loop was designed using a nonlinear dynamic inversion (NDI) control law, and the angular rate loop controller using the SBB approach. In the joint two-loop angular controller, the overall controller was designed using a backstepping technique with each loop stabilized recursively. Both angular controllers were validated using the RECOVER model with a focus on dealing with perturbed aircraft flight performance caused by failures. Two benchmark fault scenarios were selected: a rudder runaway case and a flight 1862 engine separation scenario. Simulation results showed that both control setups can guarantee the safety of the post-failure aircraft and achieve a proper reference tracking performance. In comparison with the hybrid NDI/SBB angular controller, the joint SBB angular controller resulted in a better reference tracking performance for the sideslip angle, especially in the engine separation case. An SBB controller contains a time scale parameter, other incremental control laws such as incremental NDI (INDI) and incremental backstepping (IBKS) involve a control effectiveness matrix. Before we can investigate how the time scale parameter or a control effectiveness matrix affect the control performance of an incremental flight controller, the parameter variations of a control effectiveness matrix need to be estimated and analyzed. The TPS B-spline method and an immersion and invariance (I&I) method were chosen to estimate a control effectiveness matrix for an F-16 aircraft. Although the I&I approach initially was not aimed at high modeling accuracy, it was assumed in this thesis that it is able to estimate the changing trend of the control derivatives. Simulation results showed that TPS B-splines capture the changes in the control derivatives better than the I&I approach in terms of consistency. For F-16, the control effectiveness matrix does not evidently affect the control performance of an incremental flight controller when a flight maneuver is moderate in terms of the variation of angle of attack and airspeed. Further research on modular adaptive reconfigurable control is required, for example incorporating the SB-MVSB method or the WV-LSSVR method into control designs to further check how well they are suited for modular adaptive control in terms of approximation power and onboard computational efficiency. Further research on acceleration measurements based reconfigurable control should include tests on the SIMONA simulator, realistic test-flight with UAV and research aircraft.","Fly-by-wire; Aerodynamic model; Adaptive control; Fault tolerant; Reconfiguration; Flight envelope protection; Simplex spline theory","en","doctoral thesis","Ipskamp Drukkers, Enschede, The Netherlands","","","","","","","","Aerospace Engineering","Control and Simulation","","","","51.987, 4.377"
"uuid:55550df0-3279-4b65-a748-ae779df785e9","http://resolver.tudelft.nl/uuid:55550df0-3279-4b65-a748-ae779df785e9","Regional gravity field modelling with radial basis functions","Wittwer, T.B.","Klees, R.A.P. (promotor)","2009","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Physical and Space Geodesy","","","",""
"uuid:d10726c1-693c-408e-8505-dfca1810a59a","http://resolver.tudelft.nl/uuid:d10726c1-693c-408e-8505-dfca1810a59a","Beyond Classical Upscaling: Integrated Aeroservoelastic Design and Optimization of Large Offshore Wind Turbines","Ashuri, T.","Van Bussel, G.J.W. (promotor); Van Kuik, G.A.M. (promotor)","2012","Issues related to environmental concern and fossil fuel exhaustion has made wind energy the most widely accepted renewable energy resource. However, there are still several challenges to be solved such as the integrated design of wind turbines, aeroelastic response and stability prediction, grid integration, offshore resource assessment and scaling related problems. While analyzing the market of wind turbines to find the direction of the future developments, one can see a continuous upscaling of wind turbines. Upscaling is performed to harness a larger resource and benefit from economy of scale. This will pose several fundamental implications that have to be identified and tackled in advance. This research focuses on investigating the technical and economical feasibility and limits of large scale offshore wind turbines using the current dominant concept, i.e. a three-bladed, upwind, variable speed, pitch regulated wind turbine installed on a monopile in an offshore wind farm. Thus, the objective of this research is to investigate how upscaling influences the offshore wind turbines. Specifically, following questions are of interest: 1. How do the technical characteristics of the larger scales change with size and can these technical characteristics appear as a barrier? 2. How does the economy of the future offshore wind turbines change with size? 3. What are the considerations and required changes for future offshore wind turbines? To address these questions, a more sophisticated method than the classical upscaling method should be employed. This method should provide the detailed technical and economical data at larger scales and address all the design drivers of such big machines to identify the associated problems. However, interdisciplinary interactions among structure, aerodynamics and control subject to constraints on fatigue, stresses, deflections and frequencies as well as considerations on aeroelastic instability make the development of such a method a cumbersome and complex task. Among many different methods, integrated aeroservoelastic design optimization is found to be the best approach. Therefore, the scaling study of this research is formulated as an multidisciplinary design optimization problem. This method enables the design of the future offshore wind turbines at the required level of details that is needed to investigate the effect of size on technical and economical characteristics at larger scales. Using this method, 5, 10 and 20 MW wind turbines are designed and optimized, including the most relevant design constraints and levelized cost of energy as the objective function. In addition to the design of these wind turbines, the method itself shows a clear way forward for the future offshore wind turbine design methodology development. Based on these optimized wind turbines, scaling trends are constructed to investigate the behavior of a wind turbine as it scales with size. These trends are formulated as a function of rotor diameter to properly reflect the scale. Loading, mass, cost and some other useful trends are extracted to investigate the scaling phenomenon. Blades and tower as the most flexible load carrying components are examined with more attention. Using these results, the challenges of very large scale offshore wind turbines up to 20 MW range are explored and identified. These results demonstrate that a 20 MW design is technically feasible though economically not attractive. Therefore, upscaling of the current wind turbine configurations seems to be an inappropriate approach for larger offshore wind turbines.","Wind Turbine; Multidisciplinary Design; Design Optimization; Wind Turbine Aeroelasticity; Wind Turbine Aeroservoelasticity; Integrated Design; Upscaling","en","doctoral thesis","","","","","","","","2012-11-14","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:903244ed-9e6f-44ac-88b6-3dfd00c35df5","http://resolver.tudelft.nl/uuid:903244ed-9e6f-44ac-88b6-3dfd00c35df5","Design of a quality assurance system for structural laminates","Coenen, R.A.M.","Vogelesang, L.B. (promotor)","1998","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f34c2606-dbae-4182-873b-8c1a99714297","http://resolver.tudelft.nl/uuid:f34c2606-dbae-4182-873b-8c1a99714297","Interval Analysis: Contributions to static and dynamic optimization","De Weerdt, E.","Mulder, J.A. (promotor)","2010","The field of global optimization has been an active one for many years. By far the most applied methods are gradient and evolutionary based algorithms. The most appearing drawback of those types of methods is that one cannot guarantee that the global solution is found within finite time. Moreover, if the global solution is found (by chance), the methods cannot provide a guaranteed feedback to the user stating that the provided solution is the global one. Therefore, no natural stopping conditions are available for most of the existing optimization algorithms. There are, however, other tools available, which do provide the guarantee that the global solution is found and that have natural stopping conditions. Interval analysis in combination with interval arithmetic is such a tool. Interval arithmetic was initially developed to cope with rounding errors in digital computers. Using interval arithmetic, one can perform reliable computing such that catastrophic numeric errors can be prevented (the explosion of the Ariane 5 rocket on June 4, 1996 was caused by a simple numeric overflow). It was soon found, that interval arithmetic could be used to form guaranteed bounds on any type of function or numeric algorithm for any domain. These bounds provide the crucial information needed to perform global optimization. Interval analysis is the group name of all methods that use the information obtained from guaranteed bounds to solve global optimization problems. Developed in the 1960’s, interval analysis gained popularity during the 90’s when digital computers became increasingly powerful. Nowadays, interval analysis has been widely applied in the field of static optimization, i.e. optimization that does not involve differential algebraic equations, and verified integration. However, interval analysis has not been applied often in the field of dynamic optimization. The goal of the research is to investigate whether interval analysis, in combination with interval arithmetic, can be used to solve non-linear, constrained, dynamic optimization problems. Moreover, the possibility of extending existing theory in the field of static optimization is investigated. The focus of the research lies on trajectory optimization (a specific case of dynamic optimization). The most important condition of the designed solvers is that the dynamic constraints, formed by the equations of motion, must be satisfied for all time instances. To reach the research objectives, the theory and application of both interval arithmetic and interval analysis have been thoroughly investigated. The work is divided into two parts. The first part is on static optimization, which includes the discussion on interval arithmetic and describes the basics regarding interval analysis. The existing theory of inclusion functions, formed via interval arithmetic, has been evaluated and extended upon. The development of the Polynomial Inclusion Function, a new type of inclusion function, shows that significant improvements are possible in this field. During the review of interval analysis, its main virtues and limitations were demonstrated. The most important advantages are the guarantee that all optimal solutions are found to any degree of accuracy and that the user knows when the solution set has been found. The main limitation is the curse of dimensionality: the computational load grows, for most problems, exponentially with al linear increase in problem dimension. The author believes that this curse is mainly caused by two aspects of the current implementation of interval analysis. The first aspect is the widening of the inclusion function due to the dependency effects. The dependency effects can be partially prevented by efficient implementation of function evaluations and through application of advanced inclusion functions. However, a generic efficient method for preventing dependency effects is still not available. The other aspect causing the curse of dimensionality is the current inefficient handling of available information. The optimization algorithms within interval analysis are commonly based on branch and bound algorithms. Through a process of elimination, one is left with a list of domains in which the optimal solution set must lie. Current methods for eliminating (part of) the domain, such as the Newton step, do not use the gathered/available information efficiently. This is mainly due to the definition of the domain and the storage of the information, i.e. keeping track of infeasible regions. It is the author’s opinion that this is the reason that the application of interval analysis is limited to solving lower dimensional problems. Despite the curse of dimensionality, interval analysis based solvers can solve complicated, non-linear, constrained problems. This has been shown in multiple chapters in the first part. Complicated problems, such as neural network output optimization and the problem integer ambiguity resolution in the field of Global Navigation Satellite Systems, are solved rigorously by interval analysis based solvers. The applications show that equality and inequality constraints are efficiently handled using interval analysis. Moreover, they show that interval analysis can be used to solve real-life problems and demonstrate that interval analysis is a strong global optimization tool. The second part of the research is on dynamic optimization, thereby focusing on trajectory optimization. The trajectory optimization problem is infinite dimensional with begin and end-point constraints, dynamic constraints (the equations of motion), and possibly additional equality and inequality constraints. The problem is infinite dimensional since the states and controls need to be specified for each time instance. In the field of trajectory optimization one can identify two classes of methods: indirect methods and direct methods. Disregarding the optimization problems for which an analytic solution is present, both classes require a transformation to make the problem solvable. Three transformation methods have been considered: control parameterization, state parameterization, and control and state parameterization. With control parameterization, the control is defined for each time step using a polynomial and the states are computed using explicit integration. For state parameterization, the states are defined and the controls are deduced via the equations of motion (implicit integration). The last method applies parameterization of both the states and controls with respect to time. Trajectories are sought that satisfy the dynamic constraints at given time instances. The nature of the transformation methods implies that the first two methods can be used to find trajectories that satisfy the dynamic constraints at all time instances, while the latter cannot be used for this purpose. Therefore, only the first two methods have been thoroughly investigated. The last method was only briefly reviewed. The main conclusion regarding the control parameterization approach is that it suffers greatly from the required explicit integration. Although verified integration is possible and sharp bounds on the trajectories can be provided, the problem is to prove the existence of a solution within a given domain of the search space. Without the ability to update the estimate of the minimal cost function value early in the optimization process, the computational load becomes very high. Despite the drawback of control parameterization, it has been demonstrate that this approach can be used to find the global solution, although, currently, only very low dimensional problems can be solved. Higher dimensional problems can be solved using the state parameterization approach. By using simplex splines, the begin- and end-point constraints can be implicitly satisfied, which significantly reduces the problem complexity. The limitation is that the approach is only suitable for fully controllable systems. For systems that are not fully controllable one needs to apply explicit integration for all dependent states. This will increase the computational load significantly and would eliminate most of the benefits of the state parameterization approach. An interval analysis based solver has been applied to solve the problem of satellite trajectory planning for formation flying. Although still suffering from the curse of dimensionality, the results demonstrate that interval analysis can be used to solve the problem rigorously. Moreover, it has been shown that the performance of the solver is superior to gradient based solvers when constraints are imposed. The main conclusion of the research is that it is possible to apply interval analysis to dynamic optimization. The current status of the solvers (in this thesis and in literature) allows one to solve only ‘lower’ dimensional problems. Radical changes in the approach of handling information and keeping track of infeasible regions must be made to make interval analysis applicable to higher dimensional problems. Despite the limitations of interval analysis, the presented results clearly demonstrate the virtues of interval analysis based solvers in the field of global optimization. Several new exciting research opportunities have been identified, such as nonlinear stability analysis using interval analysis, the combination of interval analysis and evolutionary algorithms, and a new way of forming inclusion functions to boost the efficiency of interval analysis based solvers. Overall, the potential of interval analysis is very large and the author believes that interval analysis will become one of the most important tools in the field of global optimization in the near future.","interval analysis; optimization; dynamic","en","doctoral thesis","","","","","","","","2010-09-14","Aerospace Engineering","Control and Simulation Division","","","",""
"uuid:0464a35a-c3a6-4f5f-9ee4-aec612b7dda0","http://resolver.tudelft.nl/uuid:0464a35a-c3a6-4f5f-9ee4-aec612b7dda0","Bulging of fatigue cracks in a pressurized aircraft fuselage","Chen, D.","Schijve, J. (promotor)","1991","","fatigue crack growth; residual strength; aircraft fuselage structure; damage tolerance requirements; stress biaxiality; combined bending and extension; bulge-out effect; out-of-plane deformation; fracture mechanics analysis; non-linear effect; ARALL; test set-up","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:73e1f001-2616-47ba-9e83-83a386009d73","http://resolver.tudelft.nl/uuid:73e1f001-2616-47ba-9e83-83a386009d73","An Ontology-Based Approach for Knowledge Lifecycle Management within Aircraft Lifecycle Phases","Verhagen, W.J.C.","Curran, R. (promotor)","2013","In the aerospace domain, manufacturers and operators constantly seek to improve their products and processes. Increasingly, knowledge-based applications are developed to support or automate knowledge-intensive engineering tasks, saving time and money. However, engineering knowledge changes over time, which has implications for the usability and maintainability of knowledge-based applications. The research presented in this thesis contributes to the development of theory regarding knowledge change in engineering tasks. A conceptual knowledge lifecycle model to characterise and quantify knowledge change is presented. Additionally, this thesis proposes a methodology and an ontology-based approach to support the development of robust knowledge-based applications that can cope with knowledge change. These research contributions are validated in three case studies that consider engineering tasks in the aircraft design, manufacturing and maintenance lifecycle phases. The case studies demonstrate the utility of knowledge lifeycle management as usability and maintainability of knowledge-based applications are improved.","knowledge; knowledge change; knowledge-based applications; KBE; aircraft engineering; knowledge management; knowledge lifecycle; ontology","en","doctoral thesis","BOXPress","","","","","","","2013-07-18","Aerospace Engineering","Air Transport & Operations","","","",""
"uuid:e172757c-2120-437e-a9c5-3f8e35e764ce","http://resolver.tudelft.nl/uuid:e172757c-2120-437e-a9c5-3f8e35e764ce","Dielectric barrier Discharge Plasma Actuator Characterization and Application","Correale, G.","Scarano, F. (promotor)","2016","An experimental investigation about nanosecond Dielectric Barrier Discharge (ns-DBD) plasma actuator is presented in this thesis. This work aimed to answer fundamental questions on the actuation mechanism of this device. In order to do so, parametric studies in a quiescent air as well as laminar bounded of free shear layers were performed. Amplitude and location of the input with respect to the receptivity region as well as frequency of flow actuation were investigated. This work required the implementation of acquisition techniques such as Schlieren, Particle Image Velocimetry (PIV), infrared thermography, back current shunt technique and balancemeasurements. Moreover, tools of analysis were employed such as Linear Stability Theory (LST), Proper Orthogonal Decomposition (POD) and Inverse Heat Transfer Problem(IHTP). Results revealed that the effect of a ns-DBD is that of “enhancing” the development of natural hydrodynamic instabilities of the specific field of motion. Therefore, in case of a laminar boundary layer, the effect of a ns-DBD plasma actuator was to amplify Tollmien–Schlichting waves according to linear stability theory. Such results led to understand the influence of the actuator position on the achievement of a specific flow control task. A ns-DBD is capable of producing several effects: a shock wave, a small body force and a thermal gradient within the discharge volume. Thus, three were the possible causes of flow actuation. The shock wave was found to be too weak to be capable of introducing an appreciable disturbance. As the shock wave, also the momentum injection induced by the body force produced by the pulsed discharge was found to be relatively too small to justify a control authority based on momentum redistribution within the boundary layer, for cases of relatively high freestream velocity. Thus, the thermal gradient induced within the discharge volume by the energy deposition of a high voltage nanosecond discharge is the effect capable of inducing a relatively large disturbance into the field of motion. Nevertheless, a thermal gradient within a gaseous flow induces two effects, it reduces density and increases viscosity. At the moment it is still unclear which of these two effects is more relevant. Once identified the thermal gradient as the main cause of flow control mechanism, a characterization study was performed aimed to identify the properties of a ns-DBD plasma actuator (thermal, electrical and geometrical) important tomaximize the induced thermal gradient within the discharge volume. In general, a higher efficiency is achieved by a strong dielectric material concerning thermal energy deposition. A barrier of a ns-DBD plasma actuator should be as thin as possible. However, the thickness affects also the lifetime of the barrier itself. Nanosecond pulsed DBD plasma actuators have shown to have the capability to delay leading edge separation. However, in the relevant literature, an influence of the actuation frequency on the achieved results is always reported. In order to investigate this frequency effect, a parametric study on a Backward Facing Step was performed. This geometry was selected because it mimics a fixed point laminar separation, the flow sceixnario of interest. Such flow scenario is unstable at high frequencies close to the step and low frequencies downstream the step and it naturally develops a most unstable mode within it. However, when a flow is actuated, its stability changes, so do the most unstable frequencies naturally developed within it. Results showed that the effect of actuation is the redistribution of energy among modes and that the optimal frequency of actuation must be based on the new stability achieved by the flow due to the actuation itself. Moreover, results indicated that the optimal frequency of actuation is not related to the most unstable frequencies naturally present within the base non-actuated flow. A method to quantify the efficiency of ns-DBDs in depositing energy within the discharge volume is proposed. This energy is the one that eventually contributes to the formation of the thermal gradient responsible of the flow control capabilities shown by these devices. Such method is based on simultaneous implementation of infrared thermography and back-current shunt techniques. Results showed that the overall efficiency of a ns-DBD plasma actuator is inversely proportional to the thickness of the dielectric barrier. Last part of this thesis is concerned with a demonstrative application of a ns-DBD plasma actuator on a two element airfoil, at Reynolds numbers ranging between 0.2·106 and 2 ·106. Results demonstrated its capability to delay separation, increase lift and reduce drag in the post stall regime. Moreover, the plasma actuator showed the capability to eliminate both a laminar bubble separation for small angles of attack and the hysteresis behaviour of the selected airfoil. In conclusion, this work shed some light on the flow actuation mechanism of a ns- DBD plasma actuator and deepened its basic knowledge.","plasma actuator; flow control","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynimics","","","",""
"uuid:e756a461-fd22-4406-9b1c-3afb76dbad9f","http://resolver.tudelft.nl/uuid:e756a461-fd22-4406-9b1c-3afb76dbad9f","The Development of a Design Tool for Fiber Metal Laminate Compression Panels","Verolme, J.L.","Arbocz, J. (promotor); Vogelesang, L.B. (promotor)","1995","","aeronautics; compressive loads; buckling; stiffened panels; failure; design; fiber metal laminates; aluminum","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:916b027f-4d60-459d-8eb2-d5bea69910ce","http://resolver.tudelft.nl/uuid:916b027f-4d60-459d-8eb2-d5bea69910ce","Flow Characteristics in Lean Direct Injection Combustors","Dewanji, D.","Van Buijtenen, J.P. (promotor)","2012","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:21f3fc97-d1c5-4c23-b97b-6f1d1b63dbbd","http://resolver.tudelft.nl/uuid:21f3fc97-d1c5-4c23-b97b-6f1d1b63dbbd","Numerical Methods for Water Flows with Free-Surface Gravity Waves","Lewis, M.R.","Koren, B. (promotor)","2004","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f63294a7-4b94-46b0-866d-055ca6a438bc","http://resolver.tudelft.nl/uuid:f63294a7-4b94-46b0-866d-055ca6a438bc","Fluid motions generated by the injection of an electric current","Jansen, A.J.M.","Steketee, J.A. (promotor)","1986","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:554928b8-2fd5-4dca-802f-57dcd7e8d87f","http://resolver.tudelft.nl/uuid:554928b8-2fd5-4dca-802f-57dcd7e8d87f","Compressible flow simulation on unstructured grids using multi-dimensional upwind schemes","Van der Weide, E.T.A.","Bakker, P.G. (promotor); Deconinck, H. (promotor)","1998","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1fb4367a-0713-40a9-8100-9a58ed67a4eb","http://resolver.tudelft.nl/uuid:1fb4367a-0713-40a9-8100-9a58ed67a4eb","Criteria for low-speed longitudinal handling qualities of transport aircraft with closed-loop flight control systems","Mooij, H.A.","Gerlach, O.H. (promotor)","1984","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4e81e0ef-ab1e-4c62-a8fa-661a5b64084b","http://resolver.tudelft.nl/uuid:4e81e0ef-ab1e-4c62-a8fa-661a5b64084b","The Effects of Specific Force on Self-Motion Perception in a Simulation Environment","Correia Grácio, B.J.","Mulder, M. (promotor); Bos, J.E. (promotor); Van Paassen, M.M. (promotor)","2013","","self-motion perception; motion cueing; simulation","en","doctoral thesis","","","","","","","","2013-10-31","Aerospace Engineering","Control and Simulation","","","",""
"uuid:42df5286-9ac1-4bef-8a38-63c25ae89710","http://resolver.tudelft.nl/uuid:42df5286-9ac1-4bef-8a38-63c25ae89710","Discontinuous modelling of strain localisation and failure","Wells, G.N.","De Borst, R. (promotor)","2001","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2fa59b2d-8131-4608-9eb8-61b256603516","http://resolver.tudelft.nl/uuid:2fa59b2d-8131-4608-9eb8-61b256603516","Rotorcraft responses to atmospheric turbulence","Van Gool, P.C.A.","Mulder, J.A. (promotor)","1997","","rotorcraft; turbulence; simulation","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:07c6f2be-3a70-42aa-97b3-894a5770454d","http://resolver.tudelft.nl/uuid:07c6f2be-3a70-42aa-97b3-894a5770454d","The GNSS integer ambiguities: Estimation and validation","Verhagen, S.","Teunissen, P.J.G. (promotor)","2005","The principle of positioning with the Global Positioning System (GPS) is based on determining the distance of at least four GPS satellites to a receiver. For that purpose the so-called code measurements can be used, so that the position of the receiver can be determined up to several meters. In order to allow for navigation with centimeter accuracy, it is however required to use the very precise carrier phase measurements, since the phase of the carrier wave of the GPS signal can be measured up to several millimeters. Unfortunately, a receiver can only measure the phase of the carrier ââ¬â that is the fraction of the wavelength at the time of arrival. The wavelength is approximately 20 centimeters, and it is not known how many complete waves have preceded the one at the time of arrival. Therefore the phase measurements are called ambiguous. And that brings the problem of 'integer ambiguity resolution'. The goal of this research has been to set up a procedure for ambiguity resolution, such that there is a sound theoretical foundation for the estimation as well as the validation procedure. Until now that was not the case. Different approaches have been considered, and it was shown that an optimal method can be set up, based on the new principle of Integer Aperture estimation. But there are also alternative methods, which are computationally more attractive, and for which it has been shown that their solution is close to optimal. Furthermore, it has been shown that the principle of Integer Aperture estimation gives a theoretical foundation for the traditional validation procedures, as used until now. The result of this research is, that there is now a complete theory available, which gives a solution to the problem of integer ambiguity resolution. This allows for the first time to make inferences on the statistical reliability of the estimated ambiguities. This is an important step, since for many applications not only precision but also reliability is a very important measure in order to decide whether or not one can safely use the navigation system.","global navigation satellite systems; integer ambiguity resolution; estimation and validation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a3280fd3-8a4d-4f22-b4d2-fed577cfb01f","http://resolver.tudelft.nl/uuid:a3280fd3-8a4d-4f22-b4d2-fed577cfb01f","Improving industrial maintenance contract relationships","De Jong, A.","Smit, K. (promotor)","2010","Unavailability of technical systems, such as aircraft, is expensive. Technical systems require maintenance to prevent and to remedy defects that cause unavailability. Users of technical systems usually bear the consequences of the risk of unavailability, in particular the loss of productivity. This is based on the presumption that users are best able to insure the risks, although maintenance organisations may be more capable to mitigate the risks. The risks are seldom allocated to maintenance organisations because users and maintenance organisations tend to have conflicting objectives. This raises the questions if a maintenance organisation can be motivated to pursue the objective of the user. This would be possible if the maintenance organisation is rewarded for the “commercial success of the user of the technical system”. If the maintenance organisation indeed pursues the objective of the user of the technical system, the maintenance organisation can make autonomous decisions about the maintenance activities. And if the maintenance organisation can make decisions, it can make investments in measures to mitigate risks, knowing that it can decide if these measures will be employed. This research shows that it is efficient and effective to transfer the risks of the unavailability of a technical system from the user to the maintenance organisation on the condition that the maintenance organisation (a) will be compensated for the risks of unavailability, (b) will be rewarded for the contribution of the technical system to the commercial success of the user, and (c) is assigned the required decision rights. This will in practice require new “collaborative” contracts that can be used for the supply of long-term maintenance services of technical systems where unavailability causes a significant economic risk, for example in aircraft maintenance.","collaboration; contracting; maintenance; management; risk","en","doctoral thesis","","","","","","","","2010-05-03","Aerospace Engineering","Aerospace Industrial Engineering and Management","","","",""
"uuid:3dd2a22a-3911-49f2-b4b2-3ba6083387ee","http://resolver.tudelft.nl/uuid:3dd2a22a-3911-49f2-b4b2-3ba6083387ee","Pilot Task Demand Load During RNAV Approaches","Heiligers, M.M.","Van Holten, T. (promotor); Mulder, M. (promotor)","2011","The question that started this research was: “Why is approach A more difficult to fly for a pilot than approach B?”. To find an answer to this question, pilots flew a large variety of Area Navigation (RNAV) approaches during several flight simulator and real flight experiments. The results of these experiments were analyzed and resulted in seven guidelines for the design of approaches. The guidelines all relate to the shape of the approach trajectory and the corresponding altitude and airspeed constraints. When these guidelines are followed, the difficulty of flying the approach, as experienced by the pilot, is predicted to be acceptable. These guidelines can consequently be used during the design of approaches. To be able to predict, in the early stages of approach design, whether an approach complies with these seven guidelines, a computer simulation program was developed and validated. The output of the simulation is conveniently arranged, and produced within a minute. As an example of the output: for two of these guidelines, the simulation program gives an indication of the percentage of flights that will meet the altitude and airspeed constraints at the waypoints, and the percentage of flights that will achieve a stabilized approach.","task demand load; workload; pilot; approach; stabilized approach; approach design; safety; flight tests","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Design of Aircraft and Rotorcraft","","","",""
"uuid:496c78af-cf05-47b6-a35a-20609202c169","http://resolver.tudelft.nl/uuid:496c78af-cf05-47b6-a35a-20609202c169","On local panel distortions due to hot-curing adhesives","Priesnitz, K.","Benedictus, R. (promotor)","2015","For many joining applications, adhesive bonding is the favoured method. It provides the ability to join dissimilar materials such as metals and plastics. Adhesive bonds can be formed over large flange areas subsequently increasing the overall stiffness of the assembly. In some cases, however, the bonding process can lead to distortions, i.e. unwanted visible deformations, especially if thin-walled structures such as car body panels are involved. These deviations from the intent shape might not affect the structural integrity of a part, but, if visible to customers on a product’s surface, they can be considered an aesthetic flaw. Distortions can be divided in local ones, which occur close to the bond line, and global ones, which affect the geometry of the entire assembly. In this thesis, the development of local panel distortions that occur in a hot-cure cycle of an adhesive is studied. A laboratory sample is exposed to temperature cycles with different heating rates and cure temperatures; the displacement of a steel strip is monitored. The panel curvatures are measured after cure cycles with and without a dwelling step at elevated temperature before the cure temperature is reached. A simulationmodel is developed that takes thermal and chemical volume changes, the cure evolution, the liquid-solid transition and stress relaxation of the adhesive into account. Mechanical properties and expansion coefficients were measured and integrated in the simulation model. Simulation results are compared with data from the experiments. The sensitivity of the predictions of distortions to changingmaterial properties is investigated. Distortions can arise early in the cure cycle. Even during the heating phase, panels can start to deform. The model predicts well the development of distortions. The influence of the temperature cycle on distortions is also reproduced by the model due to the hypo-elastic formulation of the stress-strain relation during cure. A pre-cure step can be used to reduce distortions. The model can reproduce that. Improvements, however, might be in a range in which also other effects play a role, such as deviations of adherends from an intended shape before the bonding process. Predictions showed different sensitivities to changing material constants. In a set-up where the adhesive is not confined, the bulk modulus did not show any significant influence on the predictions of distortions, so that an estimate for it may suffice. Chemical shrinkage, however, needs to be measured in-situ or should be corrected from measurements at roomtemperature to fit the real behaviour at elevated temperatures, since the influence on distortions is strong. The gel point, as the transition point from liquid to solid, has also a significant influence on predictions of distortions and should be determined with sufficient accuracy.","adhesive bonding; automotive; bond-line readout; bond-line read-through; chemical shrinkage; cure; distortion; residual stress; surface defect","en","doctoral thesis","","","","","","","","2015-10-02","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:35643690-a36d-4d40-b215-e23c2c4947a6","http://resolver.tudelft.nl/uuid:35643690-a36d-4d40-b215-e23c2c4947a6","Evolving Microstructures in Carbon Steel: A Neutron and Synchrotron Radiation Study","Offerman, S.E.","van der Zwaag, S. (promotor)","2003","","Phase transformations; steel; neutron depolarization; x-ray diffraction microscopy","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5a5d325e-cd81-43ee-81fd-8cf90752592d","http://resolver.tudelft.nl/uuid:5a5d325e-cd81-43ee-81fd-8cf90752592d","Pilot's perception and control of aircraft motions","Hosman, R.J.A.W.","Stassen, H.G. (promotor); Abbink, F.J. (promotor)","1996","","motion perception; simulation; control behaviour","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:615bcedc-468f-45e5-89e2-c16615312b2a","http://resolver.tudelft.nl/uuid:615bcedc-468f-45e5-89e2-c16615312b2a","Autonomous Relative Navigation for Small Spacecraft","Maessen, D.C.","Gill, E.K.A. (promotor)","2014","The thesis deals with the relative navigation between two small formation flying spacecraft. The inter-satellite distance is measured using locally generated radiofrequency ranging signals. Design considerations for the spacecraft and the relative navigation system are discussed as well as the estimation of the relative state. The influence of the number of antennas on each spacecraft, the antenna baseline, the ranging accuracy, the inter-satellite distance, and the relative motion on the relative navigation results and the observability of the system is extensively studied.","autonomous; relative; navigation; small; spacecraft; formation; observability","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:f1508865-03b4-4554-8cc0-4e9d824d3238","http://resolver.tudelft.nl/uuid:f1508865-03b4-4554-8cc0-4e9d824d3238","Piezoelectric Composite Actuators: Modelling of the Static and Dynamic Behaviour","Wiwattananon, P.","Benedictus, R. (promotor)","2013","Smart actuators, made of smart materials, are becoming more attractive in many applications because smart materials are not subjected to wear and does not require lubrication during services. Piezoelectric materials are a group of the many attractive smart materials that are being investigated for many applications today. Piezoelectric materials show fast responses, high efficiency/accuracy and operate on a large bandwidth. Composite materials are of interest because of their design flexibility and because they are lighter than other materials commonly used in aircraft and other applications. For the research reported here, a piezoelectric material was embedded in a composite material to form a piezoelectric composite actuator. This research was conducted to expand our knowledge of piezoelectric composite material actuators, and originated from the need to control air flow separation over an airfoil. There is a need to build a profound knowledge about such actuators before they can be implemented in an airfoil, and to understand which parameters influence the behaviour of piezoelectric composite material actuators under static and dynamic operating conditions. The actuators were manufactured and tested under static and dynamic conditions and the experimental results were compared to the finite element models. The models were incorporated with piezoelectric material properties that were determined experimentally. The results showed that a piezoelectric material’s response to an input stimulant, e.g. electric voltage and frequency, influences the actuator’s behaviour.","piezoelectric material; smart actuator; composite materials; actuator; active composites; multifunctional composites; static; dynamic","en","doctoral thesis","","","","","","","","2013-10-10","Aerospace Engineering","Aerospace Structures and Materials: Structural Integrity & Composites","","","",""
"uuid:93051a09-e773-49d6-8d7a-bb90474324d8","http://resolver.tudelft.nl/uuid:93051a09-e773-49d6-8d7a-bb90474324d8","Bearing Strength Characteristics of Standard and Steel Reinforced GLARE","Van Rooijen, R.G.J.","Van der Zwaag, S. (promotor)","2006","Fibre Metal Laminates (FMLs) are hybrid materials, which consist of thin metal sheets bonded together with alternating unidirectional fibre layers. This material concept has resulted in superior fatigue characteristics with respect to the metallic counterpart. Several static characteristics are however negatively influenced due to the fibre addition. This thesis focuses on the description of one of these characteristics: the bearing strength of FMLs. And based on the acquired knowledge, a solution is presented to improve the bearing strength. First, the bolt bearing strength with lateral restraint, of several FMLs of the Glare family was evaluated both experimentally and numerically. Subsequently, a finite element model was developed to describe the behaviour of FMLs under pin loading without lateral restraint. In the model, special attention is given to the interface between the different layers. The model was validated against experimental data of several FMLs. To improve the bearing strength of Glare, thin stainless steel sheets with high strength were selected as local reinforcement. Several steel reinforced Glare laminates were experimentally and numerically investigated on their bearing characteristics. While the improvement in bearing strength can also be reached using an aluminium reinforcement layer, the thin steel strip offers several benefits for actual joints in real aircraft structures. It results in a lower thickness increase and hence a lower eccentricity, which was shown to result in improved fatigue characteristics for actual joints, furthermore a material with higher stiffness is obtained.","fibre metal laminates; pin-loaded hole; bolt-loaded hole; stainless steel reinforcement","en","doctoral thesis","NIMR","","","","","","","","Aerospace Engineering","","","","",""
"uuid:767e71bd-9156-468e-9563-7e7bff0ee25b","http://resolver.tudelft.nl/uuid:767e71bd-9156-468e-9563-7e7bff0ee25b","Knowledge based method for solving complexity in design problems","Vermeulen, B.","Van Tooren, M.J.L. (promotor); Benedictus, R. (promotor)","2007","The process of design aircraft systems is becoming more and more complex, due to an increasing amount of requirements. Moreover, the knowledge on how to solve these complex design problems becomes less readily available, because of a decrease in availability of intellectual resources and reduced knowledge transfer opportunities. Aerospace companies need to capitalise on the knowledge available within their companies, in order to deal with the challenges of increasing complexity and competition. The research presented in this thesis contributes to tackling the above challenges. A knowledge based method for solving complex detailed design problems is presented. The process of setting-up a solution finding approach is discussed by means of a design problem in the detailed design of fibre metal laminate (FML) fuselage panels. The principles of knowledge based engineering (KBE) are used to setup a software application for finding solutions to the detailed design problem in FML. A method for solving complexity in design problems is presented. The method uses a structured approach of transforming the real world problem, via an expert view on the problem, to a mathematical model of the problem. Finally a solution finding strategy is tailored for the problem at hand, by combining available solution finding knowledge with expert problem solving knowledge from different knowledge domains.","fibre metal laminates; knowledge based engineering; constraint programming; heuristics; engineering ontologies","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:013544ae-6157-4479-bb1e-be81f63461f2","http://resolver.tudelft.nl/uuid:013544ae-6157-4479-bb1e-be81f63461f2","Algorithms for Indoor Positioning Systems Using Ultra-Wideband Signals","Yan, J.","Teunissen, P.J.G. (promotor); Tiberius, C.C.J.M. (promotor)","2010","Positioning systems and techniques have attracted more and more attention in recent years, in particular with satellite navigation technology as a tremendous enabler, and developments in indoor navigation. The work presented in this thesis has been conducted within the research project: \HERE: indoor positioning based on UWB radio signals"", which aims at developing an alternative solution to the indoor positioning problem, since the Global Navigation Satellite Systems (GNSSs), e.g. the Global Positioning System (GPS), generally can not provide reliable positioning services in indoor areas, due to strong signal attenuation and dense multipath e ects. The project focuses on range-based technologies, which are mainly composed of two parts: 1) ranging based on information such as Time of Arrival (ToA), Time Dierence of Arrival (TDoA) and Received Signal Strength (RSS); 2) positioning using the obtained ranging results. This four-year project has been carried out in a team composed of two Ph.D. candidates and two supervisors. As one of the Ph.D. candidates, the author of this thesis focuses on the positioning part of the project, with the main covered issues summarized as follows. Iterative Descent Methods The majority of existing systems, e.g. GPS, solve the positioning problem using Iterative Descent (ID) methods based on non-linear least-squares. Applying these ID methods for indoor positioning purpose faces the following three major problems: It is more dificult to obtain a good initial guess, which is critical for the ID methods to converge to the correct solution and converge faster. For on-earth satellite navigation applications, a good initial guess can be very easily obtained by choosing the Earth's center since the other (local) solution (if any) usually lies far in space. On the contrary, for indoor positioning, it is not as easy to obtain a good initial guess since the information on the user position is rather limited beforehand. In this thesis, we propose to use the so called direct methods or simply the geometric center of the seen transmitters, for initial guess. A thorough study of the existing direct methods is also given. The non-linear least-squares estimator is inherently biased, even with unbiased range measurements, since the expectation of the higher order terms in the final estimator is non-zero. This bias is generally negligible for GNSSs, with extremely large satelliteuser distance, but can be problematic for indoor applications with reduced geometric system scale. Based on an analysis of the bias due to nonlinearity, a scheme is proposed to test the significance of the bias. The corresponding work is validated with measurements obtained using UWB acoustic testbed. The iterative nature of the ID methods may be computationally too heavy for indoor applications, which usually require low power systems. Aiming at reducing the computational load of traditional iterative descent algorithms, a new framework is proposed for position estimation. The multidimensional non-linear localization problem is first transformed to a lower dimension and then solved iteratively. In three dimensional positioning systems, the achievable reduction on the amount of computation in each iteration is 67%. On the other hand, accurate positioning results can be obtained with this low-complexity framework, especially with TDoA measurements. Direct Methods In general, strict direct (non-iterative) least-squares solutions to nonlinear problems do not exist. However, with some assumptions or simplifications, direct least-squares positioning algorithms can be developed. In fact, there is a large number of direct methods documented in literature, scattered across the fields of radar, aerospace engineering, oceanic engineering, (acoustic) signal processing and wireless communications. Some of the documented methods are, surprisingly, identical, though the derivations are often greatly different. A deep study and a proper classification of the methods helps to achieve a better understanding, which is one of the central contributions of this thesis. It can be used to assist researchers and developers in the field to find the right choice for their applications. The direct methods provide simple to compute estimates, but they are suboptimal with the introduced simplifications. Based on the survey of the existing direct methods, a new non-iterative algorithm has been developed to improve the positioning accuracy. Theoretical proof is given that the method provides a better estimator in the sense that it corresponds to an equal or smaller value of the original least-squares objective function. It does so by exploiting two similar fully constrained models. Meanwhile, the non-iterative nature makes the algorithm attractive for low cost, low power applications. NLoS Identification/Mitigation It is widely known that the Non-Line of Sight (NLoS) effect is one of the main degraders for the position estimation accuracy. Hence, NLoS identification and mitigation is another important and hot subject regarding indoor positioning. A review of several existing NLoS identification and mitigation schemes is provided, and four new schemes are described, which are based on systematic positioning model hypothesis testing. The idea is to combine the statistics of timing- and RSS-based range measurements, and in the mean time exploit the fact that all collected measurements are related to the same unknown position. The four proposed schemes all use the combination of timing and RSS measurements because 1) the timing measurements are usually very accurate compared to RSS measurements, 2) the distributions of RSS measurements under LoS and NLoS conditions are well separated. The computational load of the schemes decreases as more simplifications are introduced, and the performance, however, is also degraded in general, except the case where most of the links are NLoS. Validation results show that, under full UWB signal bandwidth of 7.5 GHz, up to 99% correct decision rate can be achieved.","Indoor Positioning; Ultra-WideBand; Non-linear Least Squares","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:85e91d70-dcf2-47c2-892a-cad116fe845f","http://resolver.tudelft.nl/uuid:85e91d70-dcf2-47c2-892a-cad116fe845f","Hybrid Composite Structures: Multifunctionality through Metal Fibres","Ahmed, T.","Beukers, A. (promotor); Bersee, H.E.N. (promotor)","2009","The introduction of fibre reinforced polymer composites into the wings and fuselages of the newest aircraft are changing the design and manufacturing approach. Composites provide greater freedom to designers who want to improve aircraft performance in an affordable way. In this quest, researchers are looking to the area of multifunctional structures, which represents a new manufacturing and integration methodology. Composite materials are ideally suited to achieve multifunctionality because the best features of different materials can be combined to form a new material that has a broad spectrum of desired properties. Along these lines, this thesis explores the idea of structural multifunctionality of reinforced polymer composites through the addition of metal fibres. In this way, a new family of hybrid composite materials may be produced. Through their unique inherent properties, metal fibres offer the opportunity to expand the design envelope to incorporate tuneable properties such as ductility and electrical conductivity, for example. In this undertaking, the research was conducted in three main phases: (i) to define the properties of the metal fibres themselves, (ii) to determine the extent to which these properties contribute to the overall mechanical behaviour of the composite, and (iii) to manipulate the properties of the fibres to add functionality to the composite. Out of the many metal types, stainless steel was chosen for its superior mechanical properties. Three forms of fibres were identified; fibre bundles, fine wires and meshes, and mechanically tested. It was found that there were variations in properties dependant on fibre diameter, treatment and extent of surface flaws. Improvements in metal fibre-matrix adhesion were also demonstrated to be possible using traditional sheet metal surface treatments such as anodising; however, these results are limited by fibre diameter. Below a certain diameter, such surface treatments become too aggressive resulting in damage to the fibres. Emerging non-aggressive surface techniques may provide an answer to this shortcoming, but require further development for this application. Changes in mechanical behaviour in terms of low velocity impact and flexure were demonstrated for the hybrid composites with metal fibres compared to those without. A complex interaction between the matrix and the metal fibres has been identified as the mechanism responsible. Through intelligent placement of the metal fibres in the hybrid composite to exploit this interaction, various improvements in mechanical behaviour can be realised. Finally, innovative applications for hybrid composites were investigated, exploiting the electrical and thermal properties of the metal fibres. The first was aimed towards aiding thermographic non-destructive evaluation, and the second to provide an integrated ice protection system concept, thereby opening up new applications for the novel material concept through adding functionality to the structure.","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Design and Production of Composite Structures","","","",""
"uuid:4e96fb1b-693e-443e-be90-97b79a500ad6","http://resolver.tudelft.nl/uuid:4e96fb1b-693e-443e-be90-97b79a500ad6","The computation of aerodynamic loads on helicopter blades in forward flight, using the method of the accelerationpotential","Van Holten, T.","Timman, R. (promotor)","1975","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7923c925-d1a9-4ad7-aa58-3d6376dcc210","http://resolver.tudelft.nl/uuid:7923c925-d1a9-4ad7-aa58-3d6376dcc210","Piezoelectric and dielectric properties of polymer-ceramic composites for sensors","James, N.K.","Van der Zwaag, S. (promotor); Groen, W.A. (promotor)","2015","The main objective of this PhD thesis is to develop new routes and concepts for manufacturing piezoelectric ceramic-polymer composites with adequate piezoelectric properties while retaining ease of manufacturing and mechanical flexibility and explore new possibilities to maximize especially the voltage sensitivity while taking into account environmentally relevant issues such as avoiding the use of the chemical element Lead in the piezoelectric ceramics. The starting status of the field and the targets are described in Chapter 1. The production of structured Lead Zirconium Titanate (PZT)–epoxy composites, fabricated using dielectrophoresis, is described in Chapter 2. The resulting thread-like arrangement of the PZT particles in the composites was found to enhance the piezoelectric and dielectric constants of the structured composites. The piezoelectric and dielectric properties of the composites as a function of PZT volume fraction were investigated and compared with the corresponding properties of unstructured composites. The experimentally observed piezoelectric and dielectric constants of the structured and unstructured composites could be described by existing theoretical models. It was found that an attractive combination of decent flexibility and good piezoelectric voltage sensitivity could be obtained for structured composites at around 10 vol.% PZT particles loading. In Chapter 3, a Zn based ionomer was used as the new polymer matrix because of its high flexibility, decent electrical conductivity, excellent adhesion to the ceramic phase and most importantly its self-healing potential. The effective poling conditions for PZT-Zn ionomer composites were investigated and the results were compared with those for the reference PZT-EMAA (ethylene methacrylic acid copolymer) composites and monolithic PZT ceramic. The experimentally observed dielectric and piezoelectric coefficient were compared with Yamada’s model. The tensile properties and high cycle fatigue of the composites for large strain levels were also studied. It was demonstrated that the partial loss of sensorial functionality of the composites after high cyclic tensile fatigue could be recovered by thermal healing, due to the self-healing character of the polymer matrix. The goal of Chapter 4 was to develop an approach to quantify the state of poling of the PZT granules inside the Zn-ionomer matrix by using high energy synchrotron X-ray diffraction. For this study, we used a 30 vol.% Zn-ionomer PZT composite which was optimally poled as described in Chapter 3. The poling efficiency, crystallographic texture and lattice strain of the PZT particles inside the polymer matrix were determined and compared with the values for corresponding bulk ceramics reported in literature. It was shown that for an applied macroscopic field of 15 kVmm-1 the PZT particles are effectively poled, leading to a maximum ?(002) domain reorientation volume fraction, of around 0.70. It is also found that a significant tensile lattice strain, ?{111}, of 0.6% occurs in the direction of the applied electric field, indicating the occurrence of residual stresses within the 2-4 µm size diameter particles. The PZT particles within the polymeric matrix were found to experience significant elastic constraints. In Chapter 5 the processing window of PZT based piezoelectric composites was unveiled over the entire phase diagram composition range and a material selection criterion for high g33 composites was formulated. The piezoelectric and dielectric properties for the complete set of PZT ceramics were reported and correlated to their microstructure, polarisation and strain hysteresis loops. The effect of the dielectric and piezoelectric properties of the filler particles on the effective properties of their composites was studied using theoretical models. It was demonstrated that the combination of low dielectric constant and moderately high d33 of the ceramic filler can lead to lead-free piezoelectric composites having sensorial properties not having been reported ever before for composite materials. Finally, in Chapter 6 we describe the preparation of regular single phase cubic Lead- free (K, Na)xLi1-xNbO3 (KNN) piezoceramic particles using a new solid state double calcination processing route. These particles were subsequently used to create random and structured KNN-epoxy composites. Using dielectrophoresis, these cubical KNN particles were structured into one dimensional chains in an epoxy matrix. Composites produced with these powders showed piezoelectric properties about a factor of 2 higher than those of composites processed with conventionally calcined powder. The dielectrophoretically structured KNN-epoxy composites with optimized particle size and morphology showed excellent piezoelectric properties which can replace lead -containing piezoelectric composite for sensor applications in future. In Figure S.1, we present an overview of the properties of the new composites created in the course of this graduation project and note with pleasure that in many cases the properties fall outside the domains of systems known at the start of the thesis project to yield attractive properties.","","en","doctoral thesis","","","","","","","","2015-06-17","Aerospace Engineering","Aerospace Structures and Materials (ASM)","","","",""
"uuid:2c9e75bd-e2b7-46fc-a931-b1f8f26958b2","http://resolver.tudelft.nl/uuid:2c9e75bd-e2b7-46fc-a931-b1f8f26958b2","A combined experimental and numerical study of the turbulent wake","Starke, A.R.","van Ingen, J.L. (promotor)","2002","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a4fc4b94-0294-44ca-a504-277ede973d0b","http://resolver.tudelft.nl/uuid:a4fc4b94-0294-44ca-a504-277ede973d0b","Plunging motions of an elastically suspended wing with an oscillating flap: An experimental and numerical assessment","Sterenborg, J.J.H.M.","Bijl, H. (promotor)","2014","For wind turbines there is need for accurate fluid-structure interaction predictions due to among others increasing wind turbine blade length and the design of load alleviation systems based on aero-elastic blade deformations, like bend-twist coupling. Currently, engineering models are widely used to simulate fluid-structure interactions for wind turbines. These models typically have a limited accuracy and a new generation of design tools with a higher accuracy is desired. Important in the development of such tools is validation data, which is not widely available for wind turbine applications. Therefore, in this work experiments are conducted to generate validation data for wind turbine applications. An elastically suspended rigid wing with a flap oscillating at reduced flap frequencies of 0.1 < k < 0.3 is tested at a Reynolds number of Re=700 000. The wing freely moves in the cross-flow direction at angles of attack in the linear lift regime. Forces, moments and displacements are measured and uncertainties are determined. The resulting database is useful for comparative studies. For validation additional experiments are required, for which this work is valuable since the setup, data and experiences can be used as a starting point. Simulations are conducted with three aero-elastic codes of different fidelity: Theodorsens model, an inviscid panel code and an URANS solver. All simulations are 2-D and wind tunnel corrections are incorporated such that a low-cost approximation can be achieved. Part of the simulations were used initially to design the experiment and finally a benchmark study is conducted, demonstrating that good approximations of the experimental data are found with all models.","aero-elasticity; flaps; experimental; wind tunnel correction","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:d7766216-cc42-46d0-87e8-878755ce2f59","http://resolver.tudelft.nl/uuid:d7766216-cc42-46d0-87e8-878755ce2f59","Multiscale thermomechanical analysis of multiphase materials","Yadegari Varnamkhasti, S.","Benedictus, R. (promotor); Suiker, A.S.J. (promotor); Turteltaub, S. (promotor)","2015","The thermomechanical simulation of materials with evolving, multiphase microstructures poses various modeling and numerical challenges. For example, the separate phases in a multiphase microstructure can interact with each other during thermal and/or mechanical loading, the effect of which is significantly more complicated than the individual behavior of the phases. The interactive behavior also depends on the specific volume fractions and spatial distribution of the individual phases. An accurate modeling of the phases requires a thermodynamically consistent formulation and a robust numerical implementation of the evolution of the corresponding observable and internal variables. The complex nonlinear characteristics of these micromechanical models introduce substantial challenges with respect to their upscaling towards higher levels of observation, as necessary for analyzing large-scale engineering problems in a computationally efficient way. The work presented in this thesis addresses these aspects in detail by focusing on a class of multiphase steels, which are the so-called transformation-induced plasticity (TRIP) steels. This class of structural steels shows an excellent combination of strength and ductility. The transformation-induced plasticity effect can be ascribed to the presence of grains of metastable austenite that are surrounded by ferritic grains. The austenite can undergo a phase transformation when subjected to thermal and/or mechanical loading, thereby introducing an increase in the effective material strength. In addition, both the austenite and the ferritic matrix may deform plastically, which increases the overall ductility of the material. In order to explore the complex micromechanical characteristics and the practical application of this material in more detail, three main research questions were identified, of which the first one is: (1) How can a TRIP steel microstructure be modelled in a fully thermodynamically consistent way? The thermomechanical coupling is particularly relevant since in TRIP steels the phase transformation occurring during mechanical loading is accompanied by the release of a substantial amount of energy (latent heat) that, in turn, affects the mechanical response of the material. The second research question formulated is: (2) How does the response of a TRIP steel microstructure depend on the spatial distribution of the austenitic phase within the ferritic matrix? From the viewpoint of practical applications, the attention here is focused on comparing the response of a TRIP steel sample with a banded austenitic microstructure to that of a sample with randomly distributed austenitic grains. Considering the large number of degrees of freedom of these and other engineering problems, a computationally efficient implementation of the micromechanical model is necessary. This issue is reflected by the third research question, which reads: (3) Is it possible to include the micromechanical constitutive behavior and geometry of the individual phases within an computationally efficient multiscale formulation? For answering the three research questions above, the thermomechanical behavior of the TRIP steel phases is modelled in a fully coupled way, where the generation of heat associated to the martensitic phase transformation and the plastic deformation are accounted for explicitly in the thermodynamic formulation. In analogy with the decomposition of the deformation, the entropy density is separated in a reversible contribution, a transformation contribution, a plasticity contribution and a thermal-mechanical coupling contribution. The last term follows from combining mechanical and thermal constitutive information of the individual phases with basic thermodynamical requirements. One of the observations resulting from this approach is that for a single crystal of austenite the increase in temperature associated with the latent heat of transformation reduces the transformation rate and significantly reduces the transformation-induced plasticity effect. However, for an aggregate of austenitic and ferritic grains, which is representative of a TRIP steel, the delay in the transformation-induced plasticity effect due to latent heat is relatively small, since the ferric matrix absorbs the latent heat generated in the austenite and thus effectively acts as a thermal sink. To evaluate the influence of the spatial distribution of the austenitic (secondary) phase within the ferritic matrix, the effective responses for banded and dispersed austenitic microstructures are computed by means of numerical homogenization. A comparison of these microstructures shows that banded microstructures may allow for plastic localization in the ferritic matrix, which, in comparison to dispersed microstructures, diminishes the strengthening effect provided by the austenitic phase. For the performance of more demanding computational simulations at higher (macroscopic) scales of observation, an efficient multiscale approach termed the generalized grain cluster method (GGCM) was developed. The method is suitable for the prediction of the effective macroscopic behavior of an aggregate of single-crystal grains composing a multiphase steel. The GGCM is based on the minimization of a functional that depends on the microscopic deformation gradients in the grains through the equilibrium requirements of the grains as well as kinematic compatibility between grains. By means of the specification of weighting factors it is possible to mimic responses falling between the Taylor and Sachs bounds. The numerical computation is carried out with an incremental-iterative algorithm based on a constrained gradient descent method. For a multiscale analysis, the GCCM can be included at integration points of a standard finite element code to simulate macroscopic problems. A comparison with FEM direct numerical simulations illustrates that the computational time of the GGCM may be up to about an order of magnitude lower. In large-scale FEM models for structural applications, the responses at material point level thus may either follow from the GGCM alone, or from combining this method with fully-resolved FEM modeling at the level of individual grains (i.e., a combined GGCM - FE2 approach), depending on the required resolution.","multiscale methods; thermomechanical modeling; multiphase materials","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials (ASM)","","","",""
"uuid:f1d17514-77c0-4ed1-88ff-c46a1006f66d","http://resolver.tudelft.nl/uuid:f1d17514-77c0-4ed1-88ff-c46a1006f66d","Constrained stochastic simulation of wind gusts for wind turbine design","Bierbooms, W.A.A.M.","Van Bussel, G.J.W. (promotor); Van Kuik, G.A.M. (promotor)","2009","","wind energy; gust model; turbulence; extreme","en","doctoral thesis","Delft, DUWIND Delft University Wind Energy Research Institute","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8304afa4-0d6c-41f4-8df3-4ed1cd67091c","http://resolver.tudelft.nl/uuid:8304afa4-0d6c-41f4-8df3-4ed1cd67091c","Analyse van een mogelijke methode voor het meten van prestaties en stabiliteits- en besturingseigenschappen van een vliegtuig in niet-stationaire, symmetrische vluchten","Gerlach, O.H.","Van der Maas, H.J. (promotor)","1964","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:af341104-8733-40d7-94a3-82bb09952bb8","http://resolver.tudelft.nl/uuid:af341104-8733-40d7-94a3-82bb09952bb8","Application of the Kalman filter to flight path reconstruction from flight test data including estimation of instrumental bias error corrections","Jonkers, H.L.","Gerlach, O.H. (promotor)","1976","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:6e1a39dd-1581-4d87-b623-97d1dc39fb78","http://resolver.tudelft.nl/uuid:6e1a39dd-1581-4d87-b623-97d1dc39fb78","Micro Ramps in Supersonic Turbulent Boundary Layers: An experimental and numerical study","Sun, Z.","Scarano, F. (promotor)","2014","The micro vortex generator (MVG) is used extensively in low speed aerodynamic problems and is now extended into the supersonic flow regime to solve undesired flow features that are associated with shock wave boundary layer interactions (SWBLI) such as flow separation and associated unsteadiness of the interaction system. Numerous experimental and numerical studies have shown that despite their small size, such devices can alter the boundary layer properties very efficiently, when compared to the conventional vortex generators. In order to assist a more efficient design of MVGs, fundamental studies have been carried out to understand the associated wake properties such as the increased boundary layer mixing and the structure and stability of the induced vortex system. The present work is conducted in the framework of such fundamental studies. The micro ramp is among the most commonly used MVG devices and has been selected for the present investigations. The research is based both on wind tunnel experiments and numerical simulations in order to build a more comprehensive and detailed understanding of the flow behind a micro ramp immersed in a supersonic turbulent boundary layer. The choice of the experimental approach is justified by the fact that the incoming turbulent boundary layer exhibits a high Reynolds number (Re?=13,600), which makes it too challenging for extensive CFD investigation by using LES or DNS approaches. Variants of the micro ramp configuration as well as the attendant SWBLI can be studied efficiently by wind tunnel experiments adopting PIV as velocity field diagnostics. The use of numerical simulations by the implicit large eddy simulation (ILES) technique for one specific case enables the detailed inspection of the flow field that adds to the understanding of the flow development in regions or aspects where the experimental method provides limited access. Finally, there is general interest to know that till what extent numerical simulations can correctly identify the governing mechanisms of the boundary layer flow manipulation by micro ramps. Tomographic PIV is used as three-dimensional flow diagnostic technique in the investigation of flow organization in the micro ramp near wake (x/h?9~15). From the experimental data it is observed that the mean flow features a conical wake containing a pair of steady vortices aligned in streamwise direction. This is considered to be the basic mechanism of the boundary layer flow manipulation, whereas the wall-normal velocity component features a central focussed upwash with downwash motions at the sides. Simultaneously, a deficit region of streamwise velocity is produced in the center of the wake. The shear layer surrounding the wake is subject to Kelvin-Helmholtz (K-H) type instability and the instantaneous flow organization exhibits the formation of coherent K-H vortices that are arc shaped and dominate the velocity field fluctuations across the shear layer. Conditional averaging of the 3D velocity field yields the salient features of the interaction between the streamwise vortices and the K-H vortices whereas the former are found to be weakened at the generated of K-H vortices. The downstream decay of the flow features that are introduced by the micro ramp is relevant to its positioning with respect to the point of interaction between shock wave and boundary layer, indicating the relevance of investigating the further downstream development. Therefore experiments are conducted with large format PIV camera to study the decay in the center plane of the micro ramp far wake (x/h?12~32). In order to find a proper scaling parameter of the micro ramp wake, two geometrically similar micro ramps with different sizes are employed. Both streamwise and wall-normal velocity components exhibit a power-law decay in agreement with theories for the fully developed turbulent flow regime. The wall-normal velocity decays faster, approximately at a rate 2.5 times of the momentum deficit. The self-similarity of the velocity profiles is also examined. The streamwise velocity exhibits a good degree of self-similarity in the upper and lower shear layer, while the wall-normal component has overlapped upwash profiles. Concerning the turbulent properties, a strong anisotropy of velocity fluctuations is observed at upstream locations (x/h<20), nonetheless both fluctuation components decay to a similar magnitude when approaching the downstream end of the measurement domain (x/h>20). The organization of instantaneous vortical field is also investigated in the attempt to better understand their effect on the wake decay. Spatial auto-correlation of the instantaneous velocity fields yields the streamwise evolution of the average distance between vortices. Vortex pairing is identified in the range x/h=18~22 through an increase of such distance. The detection of counter-rotating vortices in the lower part of the wake suggests that the K-H vortices produced in the upper region of the shear layer propagate into the region close to the wall after vortex pairing, which eventually gives rise to ring-vortex formation in the later stage of the wake. A numerical study using ILES with high order scheme is carried out in collaboration with the University of Texas at Arlington. In order to establish a fair comparison with the experimental data, the flow conditions are made as similar as possible, matching the free stream Mach number and the ratio between micro ramp height and boundary layer thickness. The attendant limitations on computational resources limit the Reynolds number based on boundary layer momentum thickness to about one-third of that in the experiments. The comparison covers the most relevant quantities, such as the streamwise and wall-normal velocity and the peak vorticity. An overall good agreement is observed. A noticeable discrepancy involves underestimation of upwash motion: the wall-normal velocity amounts to 70% of the measured data. In the observation of instantaneous flow, vortex pairing is also identified and the spatial-temporal evolution of the K-H vortex is studied by tracking, which confirms the flow model conjectured from the planar PIV study in the center plane.","turbulence; flow control; Particle Image Velocimetry; Large Eddy Simulation; supersonic flow","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics Wind Energy and Propulsion","","","",""
"uuid:616c6bd1-4b7b-4c3e-bee7-1245922c3046","http://resolver.tudelft.nl/uuid:616c6bd1-4b7b-4c3e-bee7-1245922c3046","Momentum transfer and heat diffusion in the mixing of coaxial turbulent jets surrounded by a pipe","Acharya, Y.V.G.","Burgers, J.M. (promotor); Broer, L.J.F. (promotor)","1954","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6bcb6aa4-2a0f-4ca2-93cb-e2fe7abdbd41","http://resolver.tudelft.nl/uuid:6bcb6aa4-2a0f-4ca2-93cb-e2fe7abdbd41","Ecological Approach to Pilot Terrain Awareness","Borst, C.","Mulder, J.A. (promotor); Mulder, M. (promotor)","2009","The upgrade of the flight deck instruments from electro-mechanical dials and gauges towards computer-driven systems and interfaces was a necessary step to accommodate the increasing demands in flight technical performance and safety. The upgrade was a relatively slow process, however, where new systems were developed and installed as soon as the technology was available. As a result, many systems are not always well integrated in terms of presenting information. Together with the increasing amount of automation, the flight deck has become prone to issues such as information ambiguities and misunderstandings between the pilot and the (automated) avionic systems. This phenomenon is commonly labeled as a lack of ""situation awareness"" (SA) and has become a new cause for accidents. That is, pilots are unaware sometimes of the current flight situation, a situation that in itself may be caused by the automation. A recent example of this phenomenon is the Turkish Airlines accident near Schiphol on February 25 2009. The focus of this thesis is on aircraft terrain avionics, such as the Terrain Awareness Warning System (TAWS) and the Synthetic Vision System (SVS), that form a typical illustration of the evolution process and its issue regarding SA. The work in this thesis aimed to identify and address the missing information that would span the information gaps between the SVS and the TAWS to benefit pilot SA. The Ecological Interface Design (EID) framework was explored to accomplish this goal. EID was originally developed for the process industry (like nuclear power plants) and is therefore a rather novel approach in the field of flight deck design. The results of experimental evaluations indicated that pilots managed to benefit from the ecological interface enhancements to successfully and safely deal with hazardous terrain conflicts, even when encountering unanticipated events. It was found that the ecological interfaces made pilots more aware of the aircraft capabilities and much more actively involved in the decision-making loop to prevent fatal mishaps.","ecological interface design; cognitive systems engineering; flight displays; situation awareness; aviation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:6a99fed3-47f7-4153-a8a6-39df14196c53","http://resolver.tudelft.nl/uuid:6a99fed3-47f7-4153-a8a6-39df14196c53","Dynamics, Distributed Control and Autonomous Cluster Operations of Fractionated Spacecraft","Chu, J.","Gill, E.K.A. (promotor)","2015","Fractionated spacecraft deploy satellites' functionalities, such as computation, communication, data storage, payload operations and even power generation, onboard several modules that share those functionalities through a wireless network. With the advent of such an innovative space architecture, non-traditional attributes such as flexibility, robustness and responsiveness, in addition to cost and mass, are introduced to the implementation of space systems, and the equilibrium in the design may shift considerably. In order to enable those non-traditional attributes and thus create huge momentum for fractionated spacecraft, this thesis researches on the autonomous operations of fractionated spacecraft with a focus on cluster reconfiguration. In particular, three aspects have been studied thoroughly to lay the foundation for its implementation. First, functional, physical and organizational architectures of a fractionated infrastructure for long-term Earth observation missions have been proposed, which defines the scenario for our research hereinafter. In the scenario, four fractionated modules are considered with a reference orbit of 800km altitude and the fractionated cluster is regarded as a multi-agent system. Second, the relative motion is studied to provide the knowledge of the modules' long-term flight behavior within the passive cluster. This thesis presents closed-form solutions for the problem of long-term satellite relative motion in the presence of J2 perturbations, and introduces a design methodology for long-term passive distance-bounded relative motion. Last but not least, centralized and distributed approaches to the problem of autonomous cluster reconfiguration are, respectively, developed, both for energy-optimal and time-optimal reconfigurations. In the reconfiguration planning, the non-convex collision avoidance constraints as well as the non-convex final configuration constraints have been taken into account. Theoretical results regarding to the optimality and convergence of developed algorithms have been obtained. All above research areas are devoted to studying, exploiting and enabling the non-traditional attributes of fractionated spacecraft. New results have been contributed to the body of knowledge in all three research aspects. For the development of fractionated space systems, our research will shed light on the cluster design, the autonomous organization of modules within the cluster, and the design of distributed energy- or time-optimal reconfiguration. Even though this thesis is focused on the future-oriented enabling technologies for fractionated spacecraft, the developed methodologies are applicable to other distributed space systems such as formation flying. Therefore, our research can be regarded as a step stone for the implementation of future autonomous distributed space systems.","fractionated spacecraft; cluster flight; autonomous operations; distributed planning; energy-optimal; time-optimal","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Chair of Space Systems Engineering, Department of Space Engineering","","","",""
"uuid:0d11b27b-9b6d-47a6-891c-a32408409b37","http://resolver.tudelft.nl/uuid:0d11b27b-9b6d-47a6-891c-a32408409b37","Liquid Crystal Sulfonated Aramids as Proton Exchange Membranes for Fuel Cell Applications","Gao, J.","Dingemans, T.J. (promotor); Picken, S.J. (promotor)","2015","Two sulfonated aramids, poly(2,2’-disulfonylbenzidine terephthalamide) (PBDT) and poly(2,2’-disulfonylbenzidine isophthalamide) (PBDI) were synthesized with the aim to explore their unique morphology for proton exchange membrane applications. Due to the different polymer structures, PBDT forms a nematic liquid crystal, whereas PBDI is isotropic. Both polymers show excellent thermal stabilities (Td5% > 400 oC), high storage moduli (E’ = 3 – 15 GPa) and crosslinked films are flexible and easy to handle. Pulsed-field-gradient NMR diffusometry reveals that the in-plane water diffusion in the nematic PBDT membrane is as high as 3.3x10-10 m2/s, whereas the diffusion in amorphous PBDI is only 2.5x10-10 m2/s. Whereas neat and crosslinked PBDI shows isotropic diffusion, neat PBDT shows a high diffusion anisotropy (D?/D? = 3.0), which increases as a function of crosslink density (D?/D? = 4.6 at 80% crosslinking). This diffusion anisotropy is substantially higher than that typically observed for low molecular weight liquid crystals and for oriented polymeric conductors such as Nafion® (D?/D? ~ 2.0). The nematic order in the PBDT membrane also promotes directed ionic conductivity, i.e. Na+ conductivity in PBDT is 2.24 x 10-2 S/cm and 1.67 x 10-2 S/cm for PBDI, respectively. We propose that the rigid-rod PBDT chains form nano-scale hydrophilic channels, which act as pathways for transporting water molecules and ions.","liquid crystal polymers; sulfonated aramids; ionic crosslinking; ion transport; ordered structure; NMR diffusion","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:9882de78-1a38-4df9-af38-08fc13d3c2ac","http://resolver.tudelft.nl/uuid:9882de78-1a38-4df9-af38-08fc13d3c2ac","Dielectric sorption analysis on polymer films","Giacomelli Penon, M.","Picken, S.J. (promotor)","2007","The original goal of this research was to investigate new ways of predicting the life-time expectancy of organic coatings. Two different approaches were studied for their feasibility. The first approach was to optimise an existing measurement device, or to build one, which is able to detect (physical or chemical) changes of a coating as early as possible. In this way it would become possible to use this technique as an early-warning system for coatings, and quick evaluation of coatings would be possible. For this a set-up has been built which was named DSA or Dielectric Sorption Analysis. The basic principle of this technique is the sorption of water and simultaneously measuring the changes of the dielectric properties of the coating. Secondly the accelerated degradation devices were critically analysed on the parameters used to increase the degradation of coatings. It appeared that basic parameters like UV radiation, temperature and humidity are commonly used, along with salt spray, day and night cycles, acid rain simulation and other similar techniques. However, one parameter remained absent which was the atmospheric pressure. All other parameters were increased: UV dose, temperature, humidity cycles, etc., but the atmospheric pressure remained at 1 bar. Based on this the decision was made to investigate the effect of pressure on UV degradation. This combined approach resulted in a useful measurement device and a novel method to degrade coatings.","polymer coatings; films; water sorption; dielectric analysis; diffusion coefficient; uv degradation; elevated pressure","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a09e15be-f0ab-4b22-829c-131a0cd9865d","http://resolver.tudelft.nl/uuid:a09e15be-f0ab-4b22-829c-131a0cd9865d","Adaptive Variational Multiscale Formulations using the Discrete Germano","Akkerman, I.","De Borst, R. (promotor)","2009","A Residual-Based Large-Eddy Simulation (RB-LES) method is developed. This is done by discretizing the Navier-Stokes equations directly. A priori filtering is omitted. Analytical approximation of the subgrid scales results in a unusually-stabilized finite-element method with additional terms arising due to the nonlinearity. This RB-LES method is used to compute turbulent channel flow, resulting in accurate results. The results of the RB-LES method depend on the choice of the so-called stabilization parameters, just like those of traditional stabilized methods. To find optimal stabilization parameters a new procedure discrete Germano procedure is developed. The procedure is justified using commutativity diagrams. Tests with stabilized convection-diffusion and Stokes formulations. Indicate the procedure is indeed capable of approximately finding optimal parameters.","large-eddy simulation; variational multiscale; discrete germano","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:880605ea-fb4c-4b9b-a25e-ad610d94a5cd","http://resolver.tudelft.nl/uuid:880605ea-fb4c-4b9b-a25e-ad610d94a5cd","Fibre-matrix interfaces in thermoplastic composites: A meso-level approach","Carnevale, P.","Benedictus, R. (promotor); Bersee, H.E.N. (promotor)","2014","A strong pressure towards efficiency improvements in the aviation sector is given by stringent environmental reduction goals and by the growing and volatile fuel prices. Such pressure is even stronger considering the steady growth of air traffic forecasted for the next 20 years. Structural mass reduction is one of the ways to achieve such efficiency improvements. High performance thermoplastic composites are possible candidates for primary aircraft structures: compared to metal, they have higher specific properties and corrosion resistance, compared to thermosetting composites, they are tougher and permit lighter assemblies. The application of thermoplastic composites in aircraft structures has been, so far, mostly limited to interiors, secondary and semi-structural parts. A more extensive use of such materials, for example in large primary aircraft structures, requires an increment of the performance to cost ratio of the products, in particular through the introduction of new materials on the market. The development of new fibre-matrix combinations is however not sufficient: good fibre-matrix interface properties are crucial for obtaining good mechanical and durability properties of the materials. The knowledge on carbon fibre-high performance thermoplastic matrix adhesion in the public domain is very limited, being most published studies focused on thermosetting composites and glass fibre sizings for engineering thermoplastic composites. The development of optimised pretreatments and sizings for thermoplastic matrices requires a deeper study and understanding of the fibre-matrix adhesion mechanisms and properties in the existing systems. Carbon fibre reinforced PPS composites are relatively widely used in aircraft structures and their application in large primary aircraft structures is promoted. Little research work has however been published about the fibre-matrix interface mechanisms in carbon fibre PPS composites and no work has been reported about the effect of the interface on the mechanical behaviour of the composites. Furthermore, published composite-level studies about the fibre-matrix adhesion are mostly limited to unidirectional and cross-ply composites, leaving the field of woven fabric reinforced composites almost untouched. The research work was therefore aimed at gaining a basic characterisation of the fibre-matrix interfacial mechanisms in carbon fibre PPS composites and at characterising in-depth the effect of the interface on the mechanical behaviour of woven composites. The chemical and morphological characteristics of the carbon fibres were studied. The extra surface treatment carried out by TenCate on the fibres provided by the manufacturer was found to at least partially remove the original sizing and consequently to enhance the fibre surface area. Possible mechanisms taking place at the fibre-matrix interfaces in PPS composites were discussed. In composites containing the original fibres, a sizing interlayer, or an interphasial area in which diffusion of the sizing has taken place, is present. In Cetex PPS commercial composites, a stronger mechanical interlocking mechanism is established. In order to obtain an in-depth characterisation of the woven thermoplastic composite behaviour, static mechanical properties, damage development and failure modes were studied. Interlaminar shear, flexural, interlaminar fracture toughness, tensile, and in-plane shear properties of the composites were discussed and coupled with microscopy analysis of the failed samples. Higher interlaminar fracture toughness and cohesive failure were obtained in composites with relatively strong interface, adhesive failure in those with poor interface. Interlaminar shear, flexural and in-plane shear strengths and in-plane shear modulus were found to be notably affected by the fibre-matrix interface. In all testing conditions, the damage evolution and sample failure were enormously affected by the interfacial characteristics: delamination was found to be the prevalent failure mode in composites with poor interface, whereas brittle failures were obtained in those with strong interface. Non-contact measurement of the strain fields in in-plane shear and tensile testing was introduced as a qualitative assessment methodology for the fibre-matrix: a uniform distribution of strain was obtained in samples with relatively good interface, contrary to those with poor interface. In in-plane shear tests, the strain fields provided a visual representation of the stress-transfer ability of the interface whereas in tensile tests, the study of the strain fields allowed early identification of damage and understanding of the failure mode. An outlook on the durability of the composites was also given through in-plane shear testing, damage development and local strain studies of composites after exposure to high temperature water, Chapter 8. Exposure to water was found to anticipate, but not alter, the failure mechanisms observed in in-plane shear testing of dry samples.","thermoplastic composites; fibre-matrix interfaces; fibre surface treatment","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:af1f1ad0-2066-48e0-949a-6b17291c111d","http://resolver.tudelft.nl/uuid:af1f1ad0-2066-48e0-949a-6b17291c111d","Global gravity field recovery from satellite-to-satellite tracking data with the acceleration approach","Liu, X.","Klees, R. (promotor)","2008","","leo orbit dertermination; global gravity field modeling; kinematic orbit; kbr measurements; acceleration approach; water storage variation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ab47bc4a-3df5-4190-ac38-2684c8a2bf39","http://resolver.tudelft.nl/uuid:ab47bc4a-3df5-4190-ac38-2684c8a2bf39","A new approach to model the kinematics of crustal deformation with applications to the Aegean and Southeast Asia","Nyst, M.C.J.","Ambrosius, B.A.C. (promotor); Spakman, W. (promotor)","2001","An important factor in the study of lithospheric deformation is an accurate representation of the kinematics of the Earth's crust. This thesis presents a new inversion method to model the present-day kinematics of the deformation field of the Earth's surface by the use of (space) geodetic measurements of relative motion. The aim of the method is to represent the kinematics of the crustal deformation field without implicitly relating kinematics to the style of deformation at depth and without restrictions about the spatial scale of the region under consideration. The method inverts relative motions between all pairs of stations of a particular velocity data set (in this thesis mainly GPS data), in a regularized least-squares approach, for the velocity gradient field in crustal blocks and for fault motion on the active faults or block boundaries. The method is applied to a synthetic velocity field and to data sets obtained in the Aegea and at Southeast Asia. The results from the synthetic application are promising: The data are fit within their error bounds for solutions that result in a good model fit, are well resolved and have acceptable covariance. In general, the results from the application to the Aegean data are in good agreement with paleomagnetic, geodetic and geologic observations. This conclusion suggests that the deformation field reflects larger-scale crustal block motion. A new, detailed view on the present-day kinematics of the Aegean crustal deformation field is presented. The results from the application to a combination of GPS data sets obtained in Southeast Asia demonstrates that inverting for velocity gradient and fault motion simultaneously enables the accommodation of localized motion on faults or plate boundaries and offers insight in the distribution of relative plate motion in plate boundary zones in terms of slip, (micro-)block rotation and strain rates.","crustal deformation; Aegean; Southeast Asia","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e46f53c6-00dc-40f8-b997-b07f03d8ca3c","http://resolver.tudelft.nl/uuid:e46f53c6-00dc-40f8-b997-b07f03d8ca3c","Maximum likelihood parameter identification of flexible spacecraft","","Gerlach, O.H. (promotor)","1987","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ff6eaf63-ac57-492e-a680-c7a50cf5c1cf","http://resolver.tudelft.nl/uuid:ff6eaf63-ac57-492e-a680-c7a50cf5c1cf","The near wake of the VAWT: 2D and 3D views of the VAWT aerodynamics","Simao Ferreira, C.J.","Van Bussel, G.J.W. (promotor); Van Kuik, G.A.M. (promotor)","2009","The analysis, modeling and design of the lift-driven Vertical Axis Wind Turbine (VAWT) has challenged the wind energy community for many decades; this limited progress in knowledge has severely impaired the development of the VAWT, giving rise to the myth that the VAWT rotor is inherently inefficient (in comparison with the more conventional Horizontal Axis Wind Turbine - HAWT) or too complex for commercial implementation. In this research work, we take a new path on the analysis of the VAWT: instead of considering a rotor that creates a perturbation on the flow (wake and induction field), we consider an unsteady wake, to which a rotor energy-conversion system is associated, obtaining the loading on the blade by better understanding the flow. The research aims at understanding the wake and its relation with energy conversion and the loading on the rotor system. Four main questions drive this research: What is the relation between blade loading and energy conversion? How does the near wake of the VAWT develop? What is the difference between the 2D and the 3D wake? How does understanding the near wake improve our design? At the end of this dissertation we achieve a clear and insightful view on the 2D and 3D aerodynamics from the point of view of the wake, that significantly improves the aerodynamic design and optimization of new VAWT rotors for energy conversion and propulsion, opening a new design space and methodology. The results and discussion presented in this dissertation are organized in five steps (see thesis outline, Chapter 1): Part I: understand the fundamental VAWT aerodynamics and how these relate with the research presented in this dissertation. Part II: understand the energy exchange process in the 2D plane by understanding the shedding of the wake over the rotation, and the wake expansion in 2D. Analyze the impact of dynamic stall on the near wake evolution, and how to extract blade load information from the near wake in dynamic stall. Part III: understand the impact of the spanwise dimension of the rotor and the role of the consequent trailing vorticity. Investigate the little known skewed flow. Part IV: understand better the energy exchange process, the wake’s generation and the decoupling between loading and energy conversion. Propose new approaches and guidelines for the aerodynamic rotor design. Part V: discuss the main results and conclusions of the research, and its impact on new aerodynamic research and design approaches, both for 2D and 3D VAWT rotors. In Part I (Chapter 2) we frame our research approach, analyzing the VAWT from a wake perspective, by considering both 2D and 3D aerodynamics of the VAWT at two different scales: aerofoil/blade scale and rotor scale. We divide the rotor in windward (315? < ? < 45?), upwind (45?< ? < 135?), leeward (135? < ? < 225?) and downwind (225? < ? < 315?) regions of the rotation. This approach obsolesces the conventional division of the rotor into upwind and downwind halves; while the upwind/downwind division is driven by angle of attack considerations (blade loading problem), this new segmentation is determined by the shedding of vorticity (energy conversion problem), a more useful and effective approach. The wake is also split into shed vorticity due to the time gradient of the bound circulation, and trailing vorticity due to the spatial gradient of the bound circulation; this division leads to our 2D and 3D analysis of the flow. In Part II, we analyze the 2D rotor and wake at two scales: rotor and blade. The two flow scales are obviously related, in the sense that the rotor’s aerodynamics are the result of the wakes generated at the several blades and the blade experiences an induction field due to the vorticity distributed over the wake at the rotor scale. The separation in blade and rotor scale is in fact a separation of two views on the total system: The rotor, as an energy exchange system, where the energy exchange results in a wake and streamline expansion. The blade, as an aerodynamic loading system, where the design-objective loading is associated with an equivalent bound circulation. The time variation of this bound circulation results in a shed wake. The 2D potential-flow analysis (Chapter 3) shows that: the conventional breakdown of the VAWT into upwind and downwind actuator systems is incorrect, leading to an overestimation of energy conversion on the upwind half of the rotation and an underestimation in the downwind half. contrary to the HAWT, the induction is not a function of the total loading, but only of the load component associated with the azimuthally varying circulation. it is possible to significantly improve Double Multiple Streamtube models by incorporating a better description of the flow. The proposed improved model clearly surpasses conventional models on the prediction of the induction and loading. the impact of the blade bound-circulation constant-term is small in comparison to the time-varying bound-circulation term; therefore, the induction field of the 2D VAWT in potential flow can be defined by only the number of blades, rotor solidity and tip-speed ratio. This allows for the obsolescence of streamtube momentum models, replaced by faster and more accurate potential flow vortex models. In Chapters 4 and 5 we visualize and quantify, experimentally and numerically, the flow field in the near wake of the blade during the upwind and leeward segments of the motion, at tip-speed ratios ? = 2, 3 and 4, using Particle Image Velocimetry (PIV). An interesting physical aspect of the vortical flow in dynamic stall, especially at low tip-speed ratios, is the transport of the shed vorticity with the blade. This transport of the vortical structures with the blade means that the geometry of the wake, due to viscous effects, differs from what is obtained with potential flow. A different spatial distribution of the shed vorticity implies a different induction field, which might imply a reduction of the effectiveness of momentum models and simple potential-flow models and change the rotor’s performance. The results show two important effects: At the rotor scale, the transport of vorticity with the blade, rolled in the leading edge/trailing edge separated vortices. At the blade scale, the importance of the small scale vortices for the oscillations on pressure distribution and loads. In Chapter 6 we use the experimental and numerical data from the previous chapters to evaluate the feasibility of extracting information from the flow/wake measured with PIV, even in dynamic stall, for improving flow analysis and model validation. In Part III we introduce the fourth dimension of our problem: the spanwise direction. The finite span leads to a non-constant spanwise distribution of circulation on the blade, and this distribution leads to the release of trailing vorticity, of which the blade tip vortex is the most prominent component. In Chapter 7 we measure the wake at the tip-vortex region of the VAWT; in Chapter 8 we combine these experimental results with 3D unsteady free-wake potential-flow simulations to: experimentally and numerically observe, quantify and analyze the generation and convection of the 3D tip vortex of the VAWT. experimentally, numerically and analytically investigate the effect of blade-tip shape on the generation and convection of the tip vortex, with focus on the added circulation due to the motion of the blade. combine experimental measurements and numerical simulations to analyze: the 3D wake of the VAWT; the interaction between shed and trailing vorticity; the roll-up and expansion of the wake in the leeward and windward regions; the in-rotor convection and inboard/outboard motion of the tip vortex; the 3D induction field; the 3D blade wake interaction during the downwind blade passage; and the effect of trailing vorticity in the spanwise distribution of circulation, including the 2D to 3D load direction reversal in the downwind blade passage. The spanwise dimension of the flow also gives rise to a new form of misalignment between the flow and the axis: skewed flow. In Chapter 9 we analyze the physics of skewed flow, flow asymmetry, near wake development, blade-wake interaction and impact on energy conversion. The analysis of the VAWT from the point of view of the 2D and 3D near wake is shown to be very effective in understanding: the physics of the flow; the energy exchange process; how the total energy exchange over one rotation actually relates to the local aerodynamic loading on the blade; the impact of implementing an essentially 2D energy conversion process into a 3D aerodynamic system; and the resulting inefficiencies due to the finite span and trailing vorticity. In Part IV (Chapter 10) we show that it is possible to decompose the VAWT design problem into designing for loading and designing for energy conversion, opening a large design space and proposing a new methodology, impacting both 2D and 3D flow. We also show that, although the 2D wake does not vary significantly with variation in the pitching axis location and blade camber, the 3D wake and performance are significantly affected by these variations. This is due to the impact that varying the bound circulation has on the release of trailing vorticity; a larger trailing vorticity generated during the upwind blade passage implies a larger induction due to trailing vorticity, and a worse interaction at the downwind blade passage. The effects of variation of camber and/or pitching axis in 2D and 3D performance are contradictory and complementary and can be simultaneously optimized. In Part V (Chapter 11) we further develop these and other main conclusions, discussing their impact on VAWT aerodynamics. The research here presented implies a break from conventional approaches to the VAWT aerodynamics, allowing for the development of new research and models, both in 2D flow (aerofoil design, rotor energy conversion optimization) and 3D flow (blade and rotor shape, non-uniform flows).","wind energy; vertical axis wind turbine; rotor aerodynamics; aerodynamics; renewable energy; sustainable development","en","doctoral thesis","","","","","","","","2009-10-13","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:e8e0f2e8-efd5-4fd9-bc67-5dbea44fc437","http://resolver.tudelft.nl/uuid:e8e0f2e8-efd5-4fd9-bc67-5dbea44fc437","Crustal rheology and postseismic deformation: Modeling and application to the Apinnenes","Riva, R.E.M.","Ambrosius, B.A.C. (promotor)","2004","","postseismic deformation; viscoelastic relaxation; normal modes","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:314e73c6-1446-4228-9ea1-2c943dd32e55","http://resolver.tudelft.nl/uuid:314e73c6-1446-4228-9ea1-2c943dd32e55","Experimental study of nonlinear vibrations of thin-walled cylindrical shells","Gunawan, L.","Zwaan, R.J. (promotor)","1998","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:788d9a74-4d6b-47fe-9e2e-f34ec2a4cf95","http://resolver.tudelft.nl/uuid:788d9a74-4d6b-47fe-9e2e-f34ec2a4cf95","Design of an object oriented Finite Element package for parallel computers","Lingen, F.J.","de Borst, R. (promotor)","2000","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1bfb5609-daa5-4eb0-bb29-2ca028756af8","http://resolver.tudelft.nl/uuid:1bfb5609-daa5-4eb0-bb29-2ca028756af8","Investigation of a Turbulent Wake in an Adverse Pressure Gradient using Laser Doppler Anemometry","Tummers, M.J.","van Ingen, J.L. (promotor)","1999","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1e34c0f4-1f84-4728-8665-e5a9b901b271","http://resolver.tudelft.nl/uuid:1e34c0f4-1f84-4728-8665-e5a9b901b271","The Smart Rotor Concept on Wind Turbines - Actuators and Structures","Hulskamp, A.W.","Beukers, A. (promotor); Van Kuik, G.A.M. (promotor)","2011","Wind turbines suffer heavily from fatigue loads but current load control concepts are not effective in mitigating them. This thesis contributes to the development of a novel concept in which the air flow over the blade is controlled through spanwise distributed devices. The work is aimed at implementing adaptive materials, such as shape memory alloys and piezo electrics to the blade's surface creating a continuously deforming surface which influences the aerodynamics. Wind tunnel tests that were conducted show that a substantial decrease in dynamic loads can be observed with a well designed system. The work is further aimed at implementing shape memory alloys into a actively deforming surface that can act as a flap on wind turbines. Shape memory alloys show an incredible power density, but once embedded the biggest limitation is the actuation frequency because the lattice transformation that drives the actuation function is driven by heat which has to be dissipated. In this thesis we present a concept for an actuator with internal cooling channels which result in a ten times faster cooling rate of the shape memory alloy and which brings the actuator in the frequency range that is needed for large wind turbines. To demonstrate this, a fuzzy logic controller to control the surface's deformation was implemented and the actuator was applied on a structural concept. The conclusion of the thesis is that the load alleviation concept through spanwise distributed devices, based on adaptive materials, shows a lot of potential. Moreover, several technical barriers for implementation of the system have been removed, but the durability of the actuator needs to be improved.","Adaptive structures; Wind turbines; Shape Memory Alloy; Load control","en","doctoral thesis","","","","","","","","2011-11-11","Aerospace Engineering","Design and Production of Composite Structures","","","",""
"uuid:df14df78-65de-47ef-8be4-e2ec96e7d51c","http://resolver.tudelft.nl/uuid:df14df78-65de-47ef-8be4-e2ec96e7d51c","The Effect of Microstructure on the Abrasion Resistance of Low Alloyed Steels","Xu, X.","Van der Zwaag, S. (promotor); Xu, W. (promotor)","2016","The thesis attempts to develop advanced high abrasion resistant steels with low hardness in combination with good toughness, processability and low alloying additions. For this purpose, a novel multi-pass dual-indenter (MPDI) scratch test approach has been developed to approach the real continuous abrasion process and unravel abrasion damage formation in construction steels, i.e. carrying out scratch tests using a large indenter with different pre-loads to generate a wide pre-scratch with stable saturated work hardening and then a small indenter sliding over the pre-scratch to evaluate the abrasion resistance and observe the failure mechanism. With this approach, an extensive experimental investigation has been conducted to study the correlation of abrasion resistance and microstructural features (phase volume fraction, morphology, grain size, etc.) so as to understand the response of microstructures on abrasive wear, and eventually provide the knowledge to guide the design of high abrasion resistant steel. A promising type of microstructure with high abrasion resistance but low hardness has been proposed. In addition, a two-stage tensile strain hardening model was applied to interpret the scratch resistance under different pre-load conditions and resulting failure mechanisms. The strength coefficient K in the Hollomon equation (?=K?^n) in this model corresponds well with that of scratch resistance.","alloy design; abrasion resistance; scratch test; abrasive wear test; microstructure; work hardening; failure mechanism; dual phase steel; martensitic steel; abrasion resistant steel","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:255d4c7e-4556-4954-90f5-b4ed032a34d7","http://resolver.tudelft.nl/uuid:255d4c7e-4556-4954-90f5-b4ed032a34d7","Goal-Adaptive Discretization of Fluid-Structure Interaction","Van der Zee, K.G.","De Borst, R. (promotor); Van Brummelen, E.H. (promotor)","2009","The simulation of complex physical phenomena, such as fluid–structure interaction, appears to be within reach in view of the significant progress in computing power over the last decades. Yet, we are still far away from what is desirable in an evermore-demanding, science-and-technology-based society. If, however, we are modest with what we need of a physical system in that we ask for specific goal quantities instead of the entire solution, then we are able to save tremendous amounts of computing effort.","goal-oriented error estimation and adaptivity; adaptive mesh refinement; fluid-structure interaction; free-boundary problems; linearized adjoint; shape calculus","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:f12389ee-9ae9-4c7e-bb99-a27da0449f6f","http://resolver.tudelft.nl/uuid:f12389ee-9ae9-4c7e-bb99-a27da0449f6f","Classifying sediments on Dutch riverbeds using multi-beam echo-sounder systems","Eleftherakis, D.","Simons, D.G. (promotor)","2013","The economic importance of the Dutch rivers is very high as they are heavily used for inland waterway transport between the Netherlands and their neighbouring countries. A minimum depth must be guaranteed to keep the rivers navigable but also to ensure that the ships can carry maximum cargo. An attractive system for obtaining information about the riverbed bathymetry is the multi-beam echo-sounder (MBES). Furthermore, the MBES received echoes due to acoustic backscatter from the sediments in theory also allow for discriminating between different sediments. The aim of the research presented in this thesis was to develop methods for discriminating between different river sediments using MBES measurements. In order to fulfil this aim, MBES surveys were performed in the Rhine river and the Meuse river between 2007 and 2010. The research shows that indeed the MBES system can be used for discriminating between the different sediments present in the river areas. In addition an important finding is that areas differing in sediment type require different classification approaches.","classification; sediments; rivers; multibeam","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Air Transport and Operations","","","",""
"uuid:9fec5718-8055-43bd-bf25-1f837f6168e4","http://resolver.tudelft.nl/uuid:9fec5718-8055-43bd-bf25-1f837f6168e4","Discontinuities in materials and structures: A unifying computational approach","Remmers, J.J.C.","De Borst, R. (promotor); Needleman, A. (promotor)","2006","Failure mechanisms in materials and structures can be studied on different length scales. On a structural level, failure can be observed as the propagation of a single crack. However, when zooming into the apparent crack tip, it is revealed that the actual failure process is set by the nucleation and growth of multiple micro-cracks that together form the dominant crack. In crystalline materials, the nucleation of cracks can be traced back to even smaller levels of observation. The collective glide of dislocations in the atomistic structure of these materials appears to be the driving mechanism for the nucleation of micro-cracks near free edges. From a mathematical point of view the creation and propagation of cracks and the glide of dislocations can be considered as evolving discontinuities in the material. This thesis focuses on the numerical representation of these discontinuities on different length scales, varying from the simulation of delamination growth in fibre-metal laminates to a model that incorporates slip due to the motion of discrete dislocations.","cohesive zone modelling; partition of unity method; delamination; dynamic crack growth; discrete dislocation analysis","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:68d8a68a-d20f-4b18-8571-1d7b439c5215","http://resolver.tudelft.nl/uuid:68d8a68a-d20f-4b18-8571-1d7b439c5215","Theoretical and operational aspects of optimal airport arrival trajectories","Vormer, F.J.","Mulder, J.A. (promotor)","2005","The thesis considers the trajectories that are used to guide aircraft from en-route flight to an airport. Although there is currently some room to adapt the trajectories to a specific situation, they are usually largely based on published standardised trajectories. In this study the potential of optimising the arrival trajectories using data about the current situation is investigated. A trajectory scheduling algorithm based on a multi-objective genetic optimisation algorithm is developed. Fast-time simulations are carried out for traffic arriving at Amsterdam Airport Schiphol. It is shown that optimising the arrival trajectories can increase throughput and has the potential of reducing impact on the environment significantly. Optimising the arrival trajectories may have implications for the pilots and air traffic controllers tasks though. It is studied by means of experiments in a flight simulator how the shape of the trajectory influences the task demand load imposed on the pilot. A number of metrics are proposed to describe the task demand load. Off-line analyses using these metrics indicate that task demand load may increase when optimised arrival trajectories are used instead of standard trajectories. It is shown though that recently proposed displays for the flight deck that give 4-D guidance information may help to reduce the task demand load. In addition, the task demand load imposed on air traffic controllers is assessed with metrics describing airspace complexity. Off-line analyses indicate that task demand load for air traffic controllers may increase in case conventional air traffic control is maintained.","air traffic management; trajectory optimisation; genetic algorithms; task demand load; 4-d aircraft displays","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:15006e44-1232-4ef2-87bd-776b249d61f5","http://resolver.tudelft.nl/uuid:15006e44-1232-4ef2-87bd-776b249d61f5","Fatigue crack propagation and delamination growth in Glare","Alderliesten, R.C.","van der Zwaag, S. (promotor); van Tooren, M.J.L. (promotor)","2005","Fibre Metal Laminate Glare consists of thin aluminium layers bonded together with pre-impregnated glass fibre layers and shows an excellent fatigue crack growth behaviour compared to monolithic aluminium. The fibres are insensitive to the occurring fatigue loads and remain intact while the fatigue cracks occur in the aluminium layers. As a consequence, part of the load is transferred through the fibre layers instead of around the crack tip in the aluminium layers, reducing the crack growth rate. The major concept in this thesis is the stress intensity at a crack tip in the metal layers of a Fibre Metal Laminate being the factor determining the extension of that crack under cyclic loading. The stress intensity factor consists of a crack opening contribution of the far field stresses in the aluminium layers, similar to monolithic aluminium, and a crack closing contribution of the intact fibres in the wake of the crack. An analytical model has been developed based on the crack opening relations. Validation with a wide range of test data, reveals a good correlation between predicted and experimental crack growth rates, crack opening contours and delamination shapes","fatigue; crack propagation; delamination growth","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3b6cc9e6-1e1c-4a3a-9121-7343d24f3531","http://resolver.tudelft.nl/uuid:3b6cc9e6-1e1c-4a3a-9121-7343d24f3531","In situ strain & cure monitoring in liquid composite moulding by fibre Bragg grating sensors","Balvers, J.M.","Beukers, A. (promotor)","2014","","Fibre Bragg grating; liquid composite moulding; cure monitoring; optical fibre","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Structural Integrity & Composites","","","",""
"uuid:3a99ae62-aef4-464b-8009-2cc33039ab63","http://resolver.tudelft.nl/uuid:3a99ae62-aef4-464b-8009-2cc33039ab63","Multilevel optimization of anisogrid lattice structures for aerospace applications","Totaro, G.","Gurdal, Z. (promotor)","2011","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:a10e2d63-399d-48e5-884b-402e9a105c70","http://resolver.tudelft.nl/uuid:a10e2d63-399d-48e5-884b-402e9a105c70","Autonomous formation flying in low earth orbit","D'Amico, S.","Ambrosius, B.A.C. (promotor); Gill, E.K.A. (promotor)","2010","Formation flying is commonly identified as the collective usage of two or more cooperative spacecraft to exercise the function of a single monolithic virtual instrument. The distribution of tasks and payloads among fleets of coordinated smaller satellites offers the possibility to overcome the classical limitations of traditional single-satellite systems. The science return is enhanced through observations made with larger, configurable baselines and an improved degree of redundancy can be achieved in the event of failures. Different classes of formation flying missions are currently under discussion within the engineering and science community: technology demonstration missions, synthetic aperture interferometers and gravimeters for Earth observation, multi-spacecraft interferometers in the infrared and visible wavelength regions as a key to new astrophysics discoveries and to the direct search for terrestrial exoplanets. These missions are characterized by different levels of complexity, mainly dictated by the payload metrology and actuation needs, and require a high level of on-board autonomy to satisfy the continuously increasing demand of relative navigation and control accuracy. This dissertation presents the first realistic demonstration of a complete guidance, navigation and control (GNC) system for formation flying spacecraft in low Earth orbit. Numerous technical contributions have been made during the course of this research in the areas of formation flying guidance, GPS-based relative navigation, and impulsive relative orbit control, but the primary contribution of this thesis does not lie in one or more of these disciplines. The innovation and originality of this work stems from the design and implementation of a comprehensive formation flying system through the successful integration of various techniques. This research has led to the full development, testing and validation of the GNC flight code to be embedded in the on-board computer of the active spacecraft of the PRISMA technology demonstration. Furthermore key guidance and control algorithms presented here are going to be demonstrated for the first time in the TanDEM-X formation flying mission. Overall this thesis focuses on realistic application cases closely related to upcoming missions. The intention is to realize a practical and reliable way to formation flying: a technology that is discussed and studied since decades but is still confined in research laboratories. Hardware-in-the-loop real-time simulations including a representative flight computer and the GPS hardware architecture show that simple techniques, which exploit the natural orbit motion to full extent, can meet the demanding requirements of long-term close formation-flying.","formation flying; guidance, navigation and control; autonomy; technology demonstration; GPS; spacecraft; proximity operations","en","doctoral thesis","Ridderprint BV","","","","","","","2010-03-01","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:c762a162-39b8-4cb0-8009-3ff792e35278","http://resolver.tudelft.nl/uuid:c762a162-39b8-4cb0-8009-3ff792e35278","Modelling of perception and action in compensatory manual control tasks","Van der Vaart, J.C.","Gerlach, O.H. (promotor); Stassen, H.G. (promotor)","1992","","","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:09d51527-5454-4c3f-9df9-cd970e1ad926","http://resolver.tudelft.nl/uuid:09d51527-5454-4c3f-9df9-cd970e1ad926","Stability analysis of anisotropic conical shells","Zhang, G.Q.","Arbocz, J. (promotor)","1993","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b1cbdf61-124c-40f0-a290-1cd1145e62ae","http://resolver.tudelft.nl/uuid:b1cbdf61-124c-40f0-a290-1cd1145e62ae","A study on ductile fracture","Broek, D.","Jongenburger, P. (promotor)","1971","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9c4e025c-b88a-41b9-aeb9-f6071388560d","http://resolver.tudelft.nl/uuid:9c4e025c-b88a-41b9-aeb9-f6071388560d","Novel routes to liquid-based self-healing polymer systems","Mookhoek, S.D.","Van der Zwaag, S. (promotor)","2010","Inspired by the current state-of-the-art and the progressing advancements in the field of self-healing materials, this thesis addresses several novel routes to advance the concept of liquid-based self-healing polymer systems. This thesis presents the concept and characterisation of a one-component solvent-based healing mechanism for thermoplastic materials and in addition to the healing strategy, a new capsular architecture is proposed for the purpose of simultaneous release of two reactants at the same location. Other liquid container designs are investigated to enhance the liquid release upon fracture (also in the case of multiple healing events) and come with less scarification of the intrinsic material properties. Chapter 2 describes the theoretical and experimental evaluation of all the material system parameters that are significant in the performance of a one component solvent-induced selfhealing mechanism for thermoplastic materials. Parameters that are investigated include solvent sorption rates, solvent induced depression of Tg and polymer diffusion coefficients. In Chapter 3 autonomous solvent-induced self-healing mechanism for PMMA are presented and investigated. The self-healing of the mechanical properties is experimental validated for different solvents and capsule volume concentration as a function of the healing time. In Chapter 4 the capsule-composite thermoplastic self-healing material is characterised qualitatively and quantitatively by X-ray tomography using SEM-based and Synchrotron X-ray facilities. The techniques allow detailed investigation into the release volume and kinetics ofhealing-agent at the damaged site. Chapter 5 presents a novel microcapsular architecture, designed for the encapsulation of two individual liquids within a single microscopic structure. These binary microcapsules have a central liquid core and are peripherally decorated with the second liquid component, which is achieved by the synthesis and application of liquid-filled Pickering particles. Chapter 6 presents a numerical study into the influence of the microcapsule geometrical shape on the performance of a self-healing material. Classical spherical shapes are compared to cylindrical ones with varying degree of anisotropy and spatial orientation. In Chapter 7 production routes are evaluated to obtain anisotropic rod-like microcapsules. The investigated routes involve droplet deformation and encapsulation in shear and elongational flow, by usage of a modified ink-jet printing technique and by creation of stable anisotropic droplets in suspension using Pickering particles. In Chapter 8 the concept for a compartmented liquid-filled fibre is given, providing an alternative to the continuous capillaries and discrete spherical microcapsules currently applied in the field of self-healing. Control over the morphology allows production of fibres with different mechanical properties that are in the order of standard composite matrix materials and have slightly lower failure strains.","self-healing; composites; microcapsules; polymers","en","doctoral thesis","","","","","","","","2010-09-06","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:96c65674-06d4-410c-87c2-b981af95211e","http://resolver.tudelft.nl/uuid:96c65674-06d4-410c-87c2-b981af95211e","Airborne Conflict Resolution in Three Dimensions","Ellerbroek, J.","Mulder, M. (promotor)","2013","The advent of automation in the cockpit has greatly affected the nature of the tasks on the flight deck, as well as requirements on the flight crew. Although the introduction of automation in aircraft undeniably improved performance and safety, it also increased complexity in the cockpit. In addition to knowledge of basic flight information, pilots are nowadays also required to keep track of how their automated systems work. This requires a coordination of tasks between automation and human actors, and a transparency of automation that can currently not always be guaranteed. The focus of this thesis is on the concept of airborne separation, which is proposed as part of both European and American plans for the future air-traffic management system. Such a system of airborne separation implies either partial or full delegation of separation responsibility from the controller to the aircrew. This should reduce workload for the controller on the ground, and consequently increase airspace capacity, but will also lead to a profound change on the flight deck. These plans will, in order to be realized, have substantial consequences for the degree of automation, both on the ground and in the cockpit. In this thesis it is argued that capturing the inherent work domain information in a functional representation should be the basis for automating the task of airborne separation. To accomplish this, a constraint-based approach, inspired by Ecological Interface Design (EID), was employed, to provide the basis for a transparent interface to automation. This method aims to make the structure of the work domain salient, and in addition to providing a basis for automation design, should yield an interface that facilitates transparency of automation, and should support operators in constructing situation awareness. Results from experiments presented in this thesis show that, regardless of the limited level of training that the participants received, they are able to use the interface concepts to find efficient resolutions. Because these kinds of displays make several complex relationships directly perceivable, they relieve pilots from cognitive work. This transforms what would otherwise be a task that requires knowledge-based problem solving, into a simple task of perception and observation, where pilots can apply basic skills and predefined rules to safely and efficiently resolve a conflict. This allows pilots to perform well, even with a limited amount of training.","Ecological Interface Design; Cognitive Systems Engineering; Human-Centered Automation; Flight Displays; Situation Awareness","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:81a155d5-9263-4d14-9d77-30c565722db8","http://resolver.tudelft.nl/uuid:81a155d5-9263-4d14-9d77-30c565722db8","Functional and stochastic modelling of satellite gravity data","Van Loon, J.P.","Klees, R.A.P. (promotor)","2008","","","en","doctoral thesis","Neteherlands Geodetic Commission, NGC","","","","","","","","Aerospace Engineering","Physical and Space Geodesy","","","",""
"uuid:66975e4a-4b2d-4933-95c5-f180b6605882","http://resolver.tudelft.nl/uuid:66975e4a-4b2d-4933-95c5-f180b6605882","Cyclic Partial Phase Transformations In Low Alloyed Steels: Modeling and Experiments","Chen, H.","Van der Zwaag Sybrand, S. (promotor)","2013","Mechanical properties of low alloyed steels are directly determined by their microstructures. Thanks to versatility in their microstructures, the mechanical properties of low alloyed steels are much more adjustable than other materials. In the industry, one of the most effective ways to obtain the microstructure for the targeted mechanical properties is via the transformation of the iron lattice from a face centered cubic (FCC) to body centered cubic (BCC). During the lattice transformation, there is also redistribution of carbon or other alloying elements between these two iron lattices. In order to precisely tune the mechanical properties of low alloyed steels, it is required to deeply understand the mechanism of the FCC to BCC transformation. This thesis aims to shed new light on local redistribution of alloying elements at the moving interface during the FCC to BCC lattice transformation ( including both the austenite to ferrite and austenite to bainite transformations in low alloyed steels), and thus improve the mechanism of these two typical phase transformations in steels. For this purpose, novel experimental approaches (the cyclic partial phase transformation approach and the interrupted cooling approach) are designed to reveal the redistribution character of alloying elements and its effect on the phase transformation kinetics. The new experimental results allow a clear discrimination between the correctness of the existing models for both the austenite to ferrite and bainite transformations. New models are also proposed to successfully predict the special features observed in the newly designed experiments. This thesis was granted Chinese Government Award for Outstanding Self-financed Students Abroad.","austenite; bainite; kinetics; steel; ferrite","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:183e959c-80e0-41ef-b2ac-b0a245a0e599","http://resolver.tudelft.nl/uuid:183e959c-80e0-41ef-b2ac-b0a245a0e599","Consequences and challenges of GLARE for structural repair and newly designed fuselage structures","Tjahjono, S.","Vogelesang, L.B. (promotor); Smit, K. (promotor)","1998","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8ceff6e6-d8e2-40d3-a8c0-57428334a551","http://resolver.tudelft.nl/uuid:8ceff6e6-d8e2-40d3-a8c0-57428334a551","Adaptation of Structured Grids Based on Weighted Least Squares Formulations","Hagmeijer, R.","Hoeijmakers, H.W.M. (promotor)","1997","","","en","doctoral thesis","Delft University of Technology, Faculty of Aerospace Engineering","","","","","","","","Aerospace Engineering","","","","",""
"uuid:02e5b9ad-9edf-4d52-98c1-9d645237bdb3","http://resolver.tudelft.nl/uuid:02e5b9ad-9edf-4d52-98c1-9d645237bdb3","Creating favorable conditions for international environmental change through knowledge and negotation, lessons from the rhine action plan and the second sulphur protocol, implications for climate change","Grünfeld, H.","Thissen, W.A.H. (promotor); Rabbinge, R. (promotor)","1999","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2167995f-ee67-49f2-bbbb-e6787399f822","http://resolver.tudelft.nl/uuid:2167995f-ee67-49f2-bbbb-e6787399f822","Computational Modeling of Tow-Placed Composite Laminates with Fabrication Features","Fagiano, C.","Gürdal, Z. (promotor)","2010","","Composites; Variable Stiffness Laminates; Finite Element NumericalModeling; Interlaminar Stress Recovery","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Design Methodology","","","",""
"uuid:c64eb373-9802-4eb4-bf9b-82a3811bbdd9","http://resolver.tudelft.nl/uuid:c64eb373-9802-4eb4-bf9b-82a3811bbdd9","Image based measurement techniques for aircraft propeller flow diagnostics: Propeller slipstream investigations at high-lift conditions and thrust reverse","Roosenboom, E.W.M.","Scarano, F. (promotor)","2011","The aim of the thesis is to measure the propeller slipstream properties (velocity and vorticity) and to assess the unsteady and instantaneous behavior of the propeller flow field at high disk loadings, zero thrust and thrust reverse using the image based measurement techniques. Along with its implementation of the techniques in industrial facilities particular propeller phenomena are addressed, such as the propeller slipstream behavior at varying angles of attack, and its interaction with the wing for thrust cases and no thrust. In addition the flowfield behavior at propeller thrust reverse is investigated. The application of PIV in industrial facilities requires special attention. Accurate and timely calibrations are performed with a tachymeter. Laser light sheet reflections are reduced using Rhodamine acrylic paint on wind tunnel models and black adhesive foils at wind tunnel walls. Very fruitful is the application of a traversing system, which enables additional time-efficient calibration procedures while only disparity corrections are necessary as well as a timely acquisition of data in multiple planes. Using these methods industrial measurements are performed with the focus on the determination of unsteady propeller phenomena. Initial measurements are performed for the investigation of a single sting propeller. Particle Image Velocimetry (PIV) is applied in order to study the vortex pattern behind the propeller. Now, several planes are measured with the intent to determine the forces on the propeller using a simplified momentum method approach. It is shown that this method depends severely on the inflow boundary conditions, making such a method impracticable for engineering estimations. Nevertheless is the investigation of the vorticity distribution considerably useful in the quantification of high loading events. Additional BOS measurements show that the propeller slipstream contraction can be determined which is useful for a validation of less advanced CFD codes. PIV is then applied to propeller flow features at high lift conditions. The slipstream of a propeller on a half-model is investigated for increasing angles of attack. The root vortices from the propeller blade are shown to introduce secondary vortices in the flow field distribution over the nacelle and the wing. A numerical calculation is available which allows addressing several aspects of the level of agreement between unsteady Reynolds-averaged Navier-Stokes calculations and phase-locked Particle Image Velocimetry measurements. Although in general the flow field distributions are comparable there are distinct differences in the vortical regions. In particular the secondary vortices caused by the root vortices are not visible in the boundary layer in the numerical computations. A comparison of the circulation strength of the tip vortices indicates that the numerical calculations suffer from significant numerical dissipation. During the analysis of the final PIV data is was found that the symmetric phase-only filter has a detrimental effect on the peak-locking. A more detailed analysis based on synthetic images shows that the phase-only filter performs badly in regions with varying particle diameter and fluctuation free flows. An artificial introduced fluctuation field shows that it overshadows the peak-locking. The symmetric phase-only was originally introduced for PIV measurements with significant reflections. It is suggested to use this filter only if it can be shown that no peak-locking is present in the data (e.g. on a sample of the free stream flow). The final PIV measurement is performed for the investigation at propeller thrust reverse. Thrust reverse is investigated for two cases. One setting has identical blade pitch angles and the second setting has alternating blade pitch angles. It is shown that the phase-locked flow fields at both cases differ significantly, although both settings deliver the same amount on negative thrust. The lesser amount of fluctuations in the second case is supported by hot-film measurements. The alternating blade pitch angles are thus a viable option for producing negative thrust on propellers. The outlook presents PIV measurements and CFD calculations on an ‘open rotor’ which indicate that there is future need for PIV measurements, in order to get an understanding of the flow field behavior as well as for the validation of numerical codes.","Propeller; Particle Image Velocimetry; PIV; Background Oriented Schlieren; BOS; Aerodynamics; Measurement techniques","en","doctoral thesis","klartext GmbH","","","","","","","2011-09-30","Aerospace Engineering","Aerodynamics","","","",""
"uuid:6837d0ad-1bd6-4baf-95ab-181af442245e","http://resolver.tudelft.nl/uuid:6837d0ad-1bd6-4baf-95ab-181af442245e","Computational localisation analysis considering stochastic imperfections","Gutiérrez de la Merced, M.A.","De Borst, R. (promotor)","1999","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:23affaa3-2bcf-4c34-8f48-3ff1667bb573","http://resolver.tudelft.nl/uuid:23affaa3-2bcf-4c34-8f48-3ff1667bb573","Aramid Reinforced Aluminium Laminates: ARALL: Adhesion problems and environmental effects: Vol. B: Environmental effects","Verbruggen, M.L.C.E.","Schijve, J.E. (promotor)","1987","","","en","doctoral thesis","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f5f6d53c-58de-4a45-9b97-0a3f112aaea1","http://resolver.tudelft.nl/uuid:f5f6d53c-58de-4a45-9b97-0a3f112aaea1","Advances in tomographic PIV","Novara, M.","Scarano, F. (promotor)","2013","This research deals with advanced developments in 3D particle image velocimetry based on the tomographic PIV technique (Tomo-PIV). The latter is a relatively recent measurement technique introduced by Elsinga et al. in 2005, which is based on the tomographic reconstruction of particle tracers in three-dimensional space from a small number of its projections obtained with digital cameras. Tomography is widely known in the medical diagnostics (e.g. computerized axial tomography) to inspect the human body. For PIV applications the problem is formulated as that of reconstructing the spatial distribution of sparse emitters (illuminated tracers). The present work initially surveys the state of advancement of the research conducted on this new measurement technique and the main bottlenecks and aspects to be improved are identified. The two major elements covered in this research are the 3D object reconstruction and the advanced analysis of the tracers motion. Concerning the first aspect, one of the recognized limitations is the exponential increase of ghost particles when a higher particle concentration is desired for high-resolution measurements (e.g. in turbulence studies). Although Tomo-PIV already outperforms other volumetric 3D techniques in terms of allowed particle tracers concentration, many efforts are constantly devoted to find ways to further increase the particle density. A novel concept is presented in this work that makes use for the first time of more than a single recording to increase the accuracy of tomographic reconstruction. This method considers that the moving particle field can be regarded as a solid object recorded from a moving imaging system. That is why the author refers to the concept of fluid tomography, whereby the two recordings of the same set of particles are “deformed back” to the same time instant when the particle tracers come to coincide and the ghost particles do not. The Motion Tracking Enhancement reconstruction technique (MTE) is described in Chapter 4 of this thesis. The validity of the MTE working principle is verified both numerically and by experiments. Its application in turbulent shear flows shows that the seeding density can be increased by a factor 4 (ppp=0.2) with respect to that currently practiced (ppp=0.05) without loss of accuracy. The focus is then set on techniques to increase the spatial resolution of velocity fields measured by tomographic PIV. The approach followed is that of locally adaptive interrogation volume, following the concept of non-isotropic resolution in PIV (Scarano 2003). The study shows a novel technique that exploits the additional degrees of freedom when adapting window shape and orientation in a 3D domain based on velocity gradient tensor invariants analysis (Chapter 5). It is shown that the measurement spatial resolution can be increased by a factor 2.5 and 1.5 across shear layers and in the core of a vortex respectively. The present work deals also with the advanced treatment of time-resolved Tomo-PIV experimental data (Chapter 6), where the accurate measurement of the velocity material derivative is of paramount importance to extract the instantaneous flow field pressure (pressure from PIV, van Oudheusden, 2013). The approach investigated here is based on the use of particle-tracking for a time-resolved sequence of 3D particle fields. Adopting a high-order polynomial basis for the particle trajectory reconstruction allows the reconstruction of long trajectories with a strong reduction of random error and nearly the complete elimination of the truncation error. The application to a 3D measurement of a transitional jet demonstrates the higher accuracy obtained for the estimate of fluid parcels acceleration and in turn of the instantaneous pressure field. The work is concluded with a synthesis of the advances obtained in this field, followed by a perspective towards the most significant upcoming developments for the tomographic PIV technique.","tomographic PIV; MART; motion tracking enhancement MTE; adaptive interrogation; particle tracking; jet flow; turbulent boundary layer","en","doctoral thesis","ipskamp brukkers","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:121dda1b-2c69-497f-b9ce-33634ae12ded","http://resolver.tudelft.nl/uuid:121dda1b-2c69-497f-b9ce-33634ae12ded","Non-linear vibrations of imperfect thin-walled cylindrical shells","Liu, D.K.","Arbocz, J. (promotor)","1988","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b3871b4b-247e-4344-91f6-bcff776e96c6","http://resolver.tudelft.nl/uuid:b3871b4b-247e-4344-91f6-bcff776e96c6","Shallow-earth rheology from glacial isostasy and satellite gravity: A sensitivity analysis for GOCE","Schotman, H.H.A.","Ambrosius, B.A.C. (promotor); Wu, P. (promotor); Vermeersen, L.L.A. (promotor)","2008","In recent years, satellite gravity missions have been launched that probe the earth's long- to mediumwavelength (1000 - 500 km) gravity field. The upcoming ESA satellite gravity mission GOCE is predicted to measure the gravity field with an accuracy of a few centimeters at spatial scales of 100 km. Such a high-resolution gravity field contains information on mass inhomogeneities in the shallow earth, for example due to the creep of low-viscosity material forced by the growth and decay of ice sheets during the last glacial cycle. In this PhD thesis we show that GOCE is predicted to be sensitive to crustal low-viscosity zones down to a resolution of 150 km, but that recovery of the long wavelengths is hampered by uncertainties in the background earth stratification and ice-load history. We develop a thermomechanical earth model and show that creep laws and heatflow data can be used as additional constraints on the rheology of the shallow earth. Finally we indicate how in the near future high-resolution information on the shallow earth and the ice-load history can be obtained from GOCE and how this information can be used to improve for example estimates of present-day sea-level change.","satellite gravity; rheology of the crust and litosphere; glacial isostatic adjustment","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3c921dd4-c9f5-439e-a412-afd0856ba689","http://resolver.tudelft.nl/uuid:3c921dd4-c9f5-439e-a412-afd0856ba689","An Integrated Approach to Aircraft Modelling and Flight Control Law Design","Looye, G.H.N.","Mulder, J.A. (promotor); Chu, Q.P. (promotor)","2008","The design of flight control laws (FCLs) for automatic and manual (augmented) control of aircraft is a complicated task. FCLs have to fulfil large amounts of performance criteria and must work reliably in all flight conditions, for all aircraft configurations, and in adverse weather conditions. Consequently, a large part of the FCL design process involves extensive simulation analyses, hardware-in-the-loop testing, and, eventually, flight testing. Multi-disciplinary aspects hereby play an important role. For example, control laws heavily influence (aerodynamic) loads on the airframe during manoeuvring and in turbulence, as well as flutter stability of the structure. These aspects are extensively addressed, but only -after- the actual design phase. As a consequence, problems that arise with other disciplines usually give rise to re-design of control law functions. This thesis proposes an FCL design process that allows multi-disciplinary aspects to be addressed from the beginning. In the first place, this requires multi-disciplinary aspects to be present in the aircraft dynamics models used for FCL design. To this end, the use of object-oriented modelling techniques is proposed, which, in contrast to contemporary techniques, inherently supports the development of models consisting of components from various engineering areas. As a specific application, its use for development of integrated flight mechanics and aeroelastic aircraft models is discussed. In the second place, multi-disciplinary FCL design requires a means to automate tuning of design parameters, since consideration of the many additional criteria make manual parameter synthesis very elaborate. For this reason, the use of multi-objective optimisation is proposed. This technique allows parameters to be optimised with respect to many, possibly conflicting, design criteria via a so-called min-max approach. The process is demonstrated on the design of control laws for automatic landing (autoland) of a passenger aircraft. The certification of autoland systems requires extensive Monte Carlo (MC) analyses to be performed in order to show that landing mishaps in all sorts of extreme conditions are very unlikely. The proposed design process allows the MC analyses to be directly addressed in the synthesis of control law parameters, so that MC analyses for certification can be passed in one shot. The proposed multi-disciplinary design process further allows the control design department to increase participation in aircraft preliminary design, by providing a means for rapid control law prototyping. This methodology allows nonlinear control laws for a specific aircraft design status to be automatically generated from an object-oriented implementation of a current flight dynamics model, using the technique of feedback linearisation and the possibility of automatic model inversion from object-oriented model implementations. For the control department, rapid prototyping allows for quick experimentation with controller structures, the selection of command variables, etc. For other engineering departments, the methodology results in early availability of representative control laws to analyse dynamic flight characteristics of the current aircraft design status.","flight dynamics; flight control; aeroelasticity; multi-disciplinary modelling; multi-objective optimisation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:92123c07-cc12-4945-973f-103bd744ec87","http://resolver.tudelft.nl/uuid:92123c07-cc12-4945-973f-103bd744ec87","Engineering models in wind energy aerodynamics: Development, implementation and analysis using dedicated aerodynamic measurements","Schepers, J.G.","Van Bussel, G.J.W. (promotor); Van Kuik, G.A.M. (promotor)","2012","The subject of aerodynamics is of major importance for the successful deployment of wind energy. As a matter of fact there are two aerodynamic areas in the wind energy technology: Rotor aerodynamics and wind farm aerodynamics. The first subject considers the flow around the rotor and the second subject considers the (wake) flow within a wind farm. For both areas calculational models have been developed which are implemented i rotor design and wind farm design codes respectively. Accurate rotor design codes enable a reliable design of wind turbines and an optimization towards a higher energy production and lower loads, i.e. towards a lower cost of energy. They are also required to avoid design errors and hence to reduce investment risks of wind turbine manufacturers. Accurate wind farm design codes are needed to predict the production losses and the load increase on turbines in a farm due to wake effects. They also support the optimization of wind farms (e.g. through farm control) by which the energy losses and the load increase from wake effects (and consequently the costs/kWh) are minimized. For both areas the complexity of models range from engineering methods to very advanced Computational Fluid Dynamics (CFD) methods. The term engineering method is meant to indicate a model which casts a complicated flow phenomenon into a transparent form. This generally goes together with an economic computer usage. In this respect it is very important to realize that wind energy design calculations are inherently very time consuming by which advanced CFD models are still beyond the routine possibilities of industry. As such engineering methods form the only alternative for that purpose. The main aim of the present thesis is then to describe several developments of the last 25 years which have led to the present generation of aerodynamic engineering models. It will be shown that much progress has been made both on the field of rotor aerodynamics as well as on the field of wind farm aerodynamics and that this progress was highly supported by the fact that dedicated aerodynamic measurement data have become available. The progress is illustrated by the engineering models which are developed and validated by ECN in several large (inter)national cooperation projects in which these measurements played an important role. The author of this thesis was heavily involved in these projects and often acted as coordinator. Since these projects were performed in close cooperation with other institutes (which used different types of models), the activities of the author can be placed in a wider context. The first part of the thesis is devoted to rotor aerodynamics. Basically the subject of rotor aerodynamics can be subdivided in two parts: The first part deals with the global flow field around a wind turbine. This type of modelling is called induction aerodynamics, since its main goal is to determine the induced velocities at the blade. The second part deals with the loads on a wind turbine blade as a response to this flow situation and is called blade aerodynamics. Current engineering models for rotor aerodynamics topic are built around the Blade Element Momentum (BEM) theory. The Blade Element Momentum theory in itself is very basic, e.g. it is derived for 2-dimensional, stationary, homogenous and non-yawed conditions. For this reason several engineering models have been developed which overcome these simplifications and which act as add-on's to the basic BEM theory. These engineering add-on's have been developed for the field of blade aerodynamics and for the field of induction aerodynamics. In this thesis a comparison is made between current engineering models and the engineering models from 25 years ago. The engineering methods from 25 years ago were not much more than the very basic BEM theory with a Prandtl tip loss correction and a turbulent wake correction. Moreover a tower shadow model based on a dipole model and a 'geometric' correction for cone and tilt angle were included, while yaw was modelled with the advancing and retreating blade effect only. Since then the models for airfoil aerodynamics have been improved by adding unsteady and three-dimensional effects. These unsteady effects can be divided in viscous dynamic stall effects and non-viscous effects at low angles of attack. The three-dimensional effects occur at the inner part of the blade where stall is delayed and at the outer part where the tip decreases the loads. In terms of induction aerodynamics, models have been added for dynamic inflow, the azimuthal variation of the induced velocity at yaw and a model for root losses. The progress in the rotor aerodynamic engineering models from ECN is mainly described along results of four subsequent IEA Tasks: IEA Task 14 and 18, IEA Task 20 and IEA Task 29(Mexnext). An IEA Task (sometimes called an IEA Annex) is a cooperative project carried out under auspices of the International Energy Agency IEA. The goal of IEA Tasks 14 and 18 was to create a database of detailed aerodynamic measurements which all have been taken on turbines under atmospheric conditions. The goal of IEA Task 20 was to analyze the measurements which have been taken by the National Renewable Energy Laboratory NREL on a 10 meter diameter wind turbine which was placed in the very large NASA-Ames wind tunnel. Finally IEA Task 29(Mexnext) analyzed the measurements which have been taken in the EU Project Mexico on a wind turbine rotor with a diameter of 4.5 meters placed in the Large Low Speed Facility (LLF) of the German Dutch Wind Tunnel (DNW). In all of these experimental programs pressure distributions were measured at different locations along the rotor blades. Moreover the Mexico experiment mapped the flow field upstream, in and downstream of the rotor plane. The detailed aerodynamic measurements from the IEA Tasks were found to be very useful in the development, improvement and validation of these engineering models because they made it possible to extract aerodynamic phenomena which are hidden in the very global information from conventional measurement programs. It is concluded that only detailed aerodynamic measurements may be used for validation of aerodynamic design models: A validation on basis of global turbine(blade) loads does not give a decisive answer on the accuracy of aerodynamic models due to the fact that 'compensating errors' may occur. Moreover it will be shown that the measurements revealed several shortcomings in aerodynamic engineering methods which partly could be 'repaired', sometimes with the help of more refined models. Several recommendations are made on rotor aerodynamics. This includes some specific further improvements which are still possible to the current state of engineering models. Amongst other things, models for the annulus averaged induction at yaw, tip loss effects and time constants at dynamic inflow can be improved further. These improvements can be established by calibrating engineering methods to results from more advanced aerodynamic models (e.g. CFD or free vortex wake methods). The background for this recommendation lies in the fact that the validation of these advanced aerodynamic models with the detailed aerodynamic measurements from the IEA Tasks showed a clear added value from such methods on these fields. Moreover it is concluded that three-dimensional and unsteady effects on the drag deserve more attention. However the most important recommendation is related to the observation of an unbalance in the aerodynamic wind energy society: Much effort is spent on the development of aerodynamic models (often of little mutual differences) but the amount of experimental validation material is (too) limited. Therefore it is recommended to intensify the activities on rotor aerodynamic measurements in both the wind tunnel and the field. Special attention should be paid to the measurement of those phenomena which, until now, are still largely concealed (e.g. boundary layer phenomena) or unclear (e.g. the relation between blade loads and underlying flow field which is found puzzling in the Mexico experiment). The present thesis also describes the progress which has been made on the field of wind farm aerodynamics. Opposite to the situation for rotor aerodynamics, where the BEM model can be appointed as the main model, the variety of models for wind farm aerodynamics is much larger. This is partly due to the fact that a wind farm aerodynamic model should cover much more aspects: It should model both the aerodynamic behavior of the rotor (which generates the wake) as well as the turbulent wake downstream of this rotor. The fact that calculational time is such an extreme constraint adds to the diversity: As a consequence CFD modelling of wind farm aerodynamics often only refers to the modelling of the wake and not to the modelling of the rotor. It also makes that wind farm and rotor aerodynamics are sometimes considered to be fully separate subjects. This is seen as an undesired development since the aerodynamics of the wake is largely determined by the aerodynamics of the rotor standing in front of the wake. In this thesis the main characteristics of the wake flow behind a wind turbine are described together with a survey of wind farm aerodynamic models. Most of the attention is focussed on an intermediate between the very basic models and the CFD codes, i.e. the parabolized wake models. These models are relatively economic in computer usage (by which they are still considered to be engineering models) where they model the so-called far wake in a physically accurate way. The disadvantage lies in the fact that they generally need an empirical treatment of the near wake. This again goes together with a very simple modelling of the rotor. The progress in wind farm aerodynamic models is then illustrated with ECN's wind farm design code Farmflow (based on the former Wakefarm wake model) which combines a parabolized k-epsilon turbulence model for the far wake with results from a physical free vortex wake method for the near wake. The measurements on wind farm aerodynamics used in this thesis mainly come from the ECN Wind Turbine Test Site Wieringermeer, EWTW. This research farm consists of five wind turbines in a line set up with a rated power of 2.5 MW and a rotor diameter and hub height of 80 meter. The turbines are extensively instrumented, where a meteorological mast is available to measure the free stream or the wake conditions. A major advantage of these measurements lies in the research environment by which data have been recorded over a very long period of high quality. The EWTW measurements revealed various new wake aerodynamic phenomena and they offered validation material for the improvement and validation of the Farmflow code. The observations on the EWTW farm are compared with those on large off-shore wind farms, the measurements of which were supplied within the EU project Upwind. In the EWTW line set-up the largest power loss due to wake effects (and hence the lowest overall power) appears at the second turbine in the farm. The turbines deeper in the farm have a slightly higher power. This is opposite to the situation in large off-shore wind farms where the power keeps decreasing for turbines deeper into the farm. This can be explained by lateral wake effects and the size of those large (array) wind farms. The power behavior in both the EWTW as well as in the large array wind farms was predicted well with Farmflow. Several conclusions on wind farm aerodynamics are drawn. The most important conclusion is that as for the situation on rotor aerodynamics, much progress has been achieved over the past decades. This is illustrated with the developments from Wakefarm to Farmflow. In the beginning of the 1990's only single wakes were considered. These were modelled with a very simple approach: The wind turbine was represented by an actuator disc with a near wake model based on momentum theory (and later empiricism). The far wake was modelled with a turbulence model tuned for non wind energy applications. Since then the near wake models has been refined and multiple wake effects are taken into account in both axial and lateral direction. Furthermore the turbulence model has been calibrated for wind turbine wake situations. For the development of wind farm engineering models in general it is very important that some CFD models entered the (research) scene in which the rotor is modelled with more advanced methods than the actuator disc approach (e.g. with actuator lines). Such advanced models can now be used for calibration of more simple models. Several subjects for wind farm aerodynamics have been identified which still need more attention. As such it is recommended to intensify research on these fields. This holds amongst other things for the validation and improvement of multiple wake models and near wake models in multiple wake situations. Also the interaction of wind farms with the outer atmosphere deserves more attention. Moreover there is a need to refine the turbulence models for wind farm aerodynamics. Another main question to be answered is the importance of rotor aerodynamics for wake aerodynamics. More specifically it should be determined whether it is justified to model the rotor as an actuator disc. The answer to this question can be found by comparing results from CFD codes, which models both the rotor and the wake in a detailed way, with results from a similar code in which the rotor is replaced by an actuator disc. As for the situation on rotor aerodynamics it is again concluded that progress on the field of wind farm aerodynamics is hampered by a shortage of high quality validation material. For this reason it is recommended to intensify the measurement activities for wind farm aerodynamics. In this thesis minimum requirements for such measurement programs are given. Measurements anyhow need to be done on full scale wind farms, preferably in combination with wind tunnel measurements. The first type of measurements yield representative information but generally lack a sufficient degree of detail for a complete interpretation of the wind farm aerodynamic problem. Furthermore field measurements are difficult to interpret due to the stochastic turbulent environment in the free atmosphere. The second type of measurements can yield very detailed and easy interpretable information but the scale of the model turbines is far too small. An interesting intermediate is then the so-called ECN scaled wind farm. This farm consists of 10 wind turbines with a rotor diameter of 7.6 m and a rated power of 10 kW. The farm is heavily instrumented where the size is sufficiently large to make the results at least to some extent, representative for full scale situations. The combination of full scale measurements, scaled farm measurements and wind tunnel measurements then forms the most complete experimental base for wind farm aerodynamics even though each type of measurements has its own drawbacks.","engineering models in wind energy aerodynamics","en","doctoral thesis","","","","","","","","2012-12-01","Aerospace Engineering","Wind Energy","","","",""
"uuid:9c6c7ce7-7227-4bab-8699-db32697c92a8","http://resolver.tudelft.nl/uuid:9c6c7ce7-7227-4bab-8699-db32697c92a8","Regional gravity field modeling using airborne gravity data","Alberts, B.A.","Klees, R.A.P. (promotor)","2009","","airborne gravimetry; regional gravity field determination; frequency-dependent data weighting","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:0542eb0e-4eb4-4a73-ae1e-338cf63d25b0","http://resolver.tudelft.nl/uuid:0542eb0e-4eb4-4a73-ae1e-338cf63d25b0","From space exploration to commercialisation","Tkatchova, S.A.","Smit, K. (promotor); Santema, S. (promotor)","2006","Space exploration has captured the imagination and dreams of many scientists, engineers and visionaries.The ISS is being built by five ISS partners; NASA, RSA, ESA, CSA and JAXA. ISS commercialisation is the process by which ISS products and services are sold to private companies, without transferring ISS ownership. This thesis has two objectives; to propose a collaboration between space agencies and commercial partners and to describe and predict strategic and market developments in ISS commercialisation. The methodology used in this research is typically case-based and collaboration creation is chosen as a major research subject for this thesis. ISS commercialisation is characterised by a cooperative oligopoly: emerging ISS markets and dependence on Russia for regular ISS access. The expected growth of the space tourism, sponsorship markets and the creation of privately funded transportation vehicles (i.e. SpaceShipOne) are some of the current market developments. Cooperative oligopoly is the expected market structure for the future ISS commercial environment. A joint venture for high market demand for ISS products and services and a licensing agreement for medium market demand are the proposed collaborations. These collaborations can also be applied for ISS partners' Moon and Mars space-exploration, navigation, earth observation and technology transfer programmes. Today's ISS commercialisation can become the basis for tomorrow's partial commercial exploitation on interplanetary space missions.","ISS commercialisation; space industry; ESA; collaborations; cooperative oligopoly; joint ventures; licensing agreements; ISS markets; non-cooperative oligopoly","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:057fa33f-82a3-4139-beb8-53f184cd1d57","http://resolver.tudelft.nl/uuid:057fa33f-82a3-4139-beb8-53f184cd1d57","On the Turbulent Mixing in Horizontal Axis Wind Turbine Wakes","Lignarolo, L.E.M.","Van Bussel, G.J.W. (promotor)","2016","The wake flow of a horizontal axis wind turbine is characterised by lower wind speed and higher turbulence than the free-stream conditions. When clustered in large wind farms, wind turbines regularly operate inside the wake of one or more upstream machines. This is a major cause of energy production loss and a source of higher fatigue loads on the rotor’s blades. In order to minimise the wake effects, a smart optimisation of the wind-turbine layout is essential and reliable method for modelling the wake behaviour is fundamental. The scientific community has broadly recognised the high level of uncertainty, which still affects the state-of-the-art numerical wake models and, in turn, leads to miscalculation of the wake effect. In order to develop more advanced models it is valuable to follow a back-to-basic approach and to investigate the physics of the transition from near-wake flow to far-wake flow. The near wake is characterised by the presence of organised structures as the tip- and root-vortex helices, which are trailed at the two extremities of each blade. In the far wake, the influence of the blade flow is no longer visible: this is the region where most of the turbulence mixing happens and the wake undergoes a re-energising process. Given the different physics governing the two regions, including in a single model a set of assumptions able to encompass both flow characteristics and to account for the influence of the near-wake features on the far-wake development is still problematic. This research explores two aspects of the wake problem, adopting an experimental, numerical and theoretical approach. In the first place, the physics of the transition from near to far wake is explored. In particular, the main aim is to study how the near-wake turbulent flow structures affect the re-energising process of the far wake, by understanding the relationship between the near-wake vortex system and the resulting turbulence structures in the wake. In second instance, the actuator disc approach, which is at the basis of most rotor as well as wake models, is studied for shedding more light onto its limitations and potentials. Stereo particle image velocimetry (SPIV) is adopted for mapping the three-component velocity field in a meridian plane encompassing a large portion of the near, transition and far wake of a two-blade wind turbine model. Measurements are carried out in the presence of an artificially-triggered tip-vortex pairing instability, the so-called leapfrogging instability, which determines the tip-vortex breakdown and the onset of a more efficient wake mixing. The analysis of the data revealed a major influence of the vortex instability on both the time-average velocity field and on the turbulence field. In particular, it was shown that the wake begins its re-energising process after the tip vortices have completed a 90 degree rotation around each other during the pairing mechanism. A second step in this analysis is the application of the triple decomposition of the flow in the shear layer at the border of the wake. With this approach, the role of the periodic and random flow motions in the turbulent mixing and wake re-energising process can be studied separately. Two components of the mean-flow kinetic-energy transport are quantified for one single phase of the rotor rotation: the mean-flow kinetic-energy flux and the turbulence production. The analysis shows that only the random flow fluctuations are yielding considerable entrainment of kinetic energy, while the near-wake vortex structure seem to act as a shield preventing the wake mixing. The study continues with the analysis of the wake of the wind turbine model compared with the one of an actuator disc. The latter is reproduced experimentally by means of a porous disc manufactured with metal mesh, having the same diameter and drag coefficient of the turbine model. Differences between the two wakes (velocity deficit, turbulence levels, mean-flow kinetic-energy transport, etc.) are quantified with SPIV measurements. The study shows that the actuator disc is in fact able to reproduce the time-average velocity field also in the very near wake with good accuracy, contrary to what is found in previous literature. Proper orthogonal decomposition (POD) of the flow field is adopted as an alternative method for separating periodic and random flow motions without the need of acquiring phase-locked measurements. This also allows estimating the mean-flow kinetic-energy flux and the turbulence production in the time-average field, rather than in one single rotation phase. The analysis confirms that major contribution to the momentum entrainment in the wind turbine wake is provided by the random flow fluctuations, while the periodic fluctuations have a zero or even negative contribution. In the actuator disc wake the kinetic energy transport is only positive and of a larger magnitude compared to the one in the wind turbine wake. The analysis of the turbulence production shows a distinct region characterised by large negative values in correspondence of the tip-vortex instability. This phenomenon constitutes a clear example of the failure of the gradient transport model in the time-mean field, which normally does not account for the possibility of reverse energy transfer from coherent structures to the mean flow. Five state-of-the-art computational fluid dynamics (CFD) codes are validated against the experimental data in a benchmark workshop organised among several academic and industrial organisations. Four large eddy simulation (LES) codes and one vortex models are used for reproducing the near wake of the porous disk. The comparison shows that, despite the lack of viscosity and turbulence models, the vortex model is capable of reproducing the wake expansion and the centreline velocity with very high accuracy. Also all tested LES models are able to predict the velocity deficit in the very near wake well, contrary to what was expected from previous literature. However the resolved velocity fluctuations in the LES are below the experimentally measured values.","wake mixing; horizontal axis wind turbines; particle image velocimetry; tip vortex instability","en","doctoral thesis","","","","","","","","","Aerospace Engineering","AWEP","","","",""
"uuid:e10f65c8-0d3e-4d2c-953b-cf460beca025","http://resolver.tudelft.nl/uuid:e10f65c8-0d3e-4d2c-953b-cf460beca025","Dielectric Barrier Discharge Actuators for Flow Control: Diagnostics, Modeling, Application","Kotsonis, M.","Scarano, F. (promotor); Veldhuis, L.L.M. (promotor)","2012","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:b676db6c-ed86-4b42-9940-9b90b94651f1","http://resolver.tudelft.nl/uuid:b676db6c-ed86-4b42-9940-9b90b94651f1","Agent-Based Modelling and Simulation of Safety and Resilience in Air Transportation","Bouarfa, S.","Blom, H.A.P. (promotor); Curran, R. (promotor)","2015","Purpose: In order to improve the safety, capacity, economy, and sustainability of air transportation, revolutionary changes are required. These changes might range from the introduction of new technology and operational procedures to unprecedented roles of human operators and the way they interact. Implementing such changes can introduce both negative and positive emergent behaviour. i.e. behaviour that arises from the interactions between system entities as proposed in innovative concepts. Currently, the inability to understand and control such behaviour prevents us from avoiding undesired negative emergent behaviours and promoting positive ones. In order to address this problem, this thesis aims to understand emergent behaviour in the complex socio-technical air transportation system. Methods: The thesis proposes Agent-Based Modelling and Simulation (ABMS) as a method for capturing emergent behaviour of the socio-technical air transportation system, and evaluating novel system designs. The popularity of ABMS is driven by its capability of handling the increasing complexity of real world socio-technical systems that exhibit emergent behaviour. This thesis focuses on two main applications namely: 1) the identification of emergent safety risk of an active runway crossing operation; and 2) the evaluation of the role of coordination in Airline Operations Control (AOC) resilience. In both applications, ABMS has emerged as a key method because it is widely used in complexity science to understand how interactions give rise to emergent behavior. The agent-based models include all relevant human and technical agents, such as pilots and controllers and the decision support systems involved. Simulation of these agents interacting together is conducted to predict the impact of both existing and future concepts of operation. Results: The applications in this thesis highlight that ABMS has the capability to reveal unexpected emergent behaviour and provide novel insights in air transportation. For the airport safety application, various types of emergent behaviour have been revealed due to the development and simulation of the agent-based model that covers the totality of interactions of components and their variability in performance over time. The Monte Carlo simulations make it possible to understand the potential of agents in restricting the risk in off-nominal scenarios, through capturing their stochastic nature and accounting for uncertainty. For the airline resilience application, novel insights were gained about the role of coordination in airline resilience. Capitalizing on established airline practice and research about human coordination from the psychology domain, the agent-based simulations evaluated the operational effects of AOC coordination policies on a challenging disruption scenario. Conclusions & possible applications and implications: This thesis demonstrates that ABMS of air transport operations is a viable approach in gaining knowledge about emergent behaviour which was unknown before. This knowledge includes both bottlenecks of system designs and identified opportunities, and hence can be used to control and further optimize the socio-technical air transportation system. This also implies that ABMS can be a cost-effective method for evaluating new concepts during the early design phase of air transport operations.","Air Transportation; Safety; Resilience; Airline Operations Control; Agent-Based Modelling and Simulation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Air Transport and Operations","","","",""
"uuid:973a564b-5734-42c4-a67c-1044f1e25f1c","http://resolver.tudelft.nl/uuid:973a564b-5734-42c4-a67c-1044f1e25f1c","Optimal Design of Variable Stiffness Composite Structures using Lamination Parameters","IJsselmuiden, S.T.","Gürdal, Z. (promotor)","2011","Fiber reinforced composite materials have gained widespread acceptance for a multitude of applications in the aerospace, automotive, maritime and wind-energy industries. Automated fiber placement technologies have developed rapidly over the past two decades, driven primarily by a need to reduce manufacturing costs and improve product consistency and quality. The introduction of new technologies often stimulates novel means of exploiting them, such as using the built-in fiber steering capabilities to manufactured composite laminates with continuously varying fiber orientation angles, yielding a so called variable stiffness laminate. These laminates allow the full potential of composite materials to be harnessed by enlarging the design space to create substantially more efficient structural designs, which has been demonstrated both theoretically and experimentally in the recent past. Despite the apparent potential, the design tools currently available to engineers do not exploit the steering capabilities of automated fiber placement machines to obtain more efficient structural solutions. The design of composite structures is by no means a trivial task. Composite structures are inherently difficult to optimize due to a combination of discrete and continuous design variables as well as generally non-convex design problems with multiple solutions. Variable stiffness laminates are even more complex to design, as the optimization problem is no longer limited to a single or several laminate designs, but consists essentially of obtaining an optimal layup at every point in the structure. Ensuring fiber continuity and laminate manufacturability complicates the design problem even further. The large number of design variables and constraints associated with variable stiffness design problems make them unusually challenging problems to solve. The substantial increase in structural efficiency possible when using variable stiffness laminates and the lack of available design tools motivated the development of computationally tractable design optimization routine for variable stiffness composite structures. The complexity of the design problem necessitated the development of a multi-step approach. Separating structural performance related design drivers and manufacturing related design drivers allows the most suitable optimization algorithms to be used where necessary. In a first step, the optimal laminate stiffness distribution is obtained for the considered structural performance metric and constraints. Using lamination parameters to parameterize the structural stiffness allows the optimization problem to be solved efficiently, as will be discussed later. Design drivers such as maximum in-plane stiffness, strength, natural frequency and buckling can be included at this stage of the optimization. The obtained optimum solution provides the designer with a conceptual stiffness distribution best satisfying the desired structural performance requirements. In a second step, the fiber angle distribution, essentially representing point-wise laminate stacking sequence, required to match the obtained optimum stiffness distribution is determined. Manufacturing constraints, such as minimum curvature, thickness buildup, or permeability, can be incorporated at this stage. In a final step, the obtained fiber angle distributions are converted to continuous fiber paths for manufacturing. The responses of variable stiffness composite structures, required at the various steps of the design process, are typically evaluated using a finite element method by assigning different stiffness properties to each element in the model. In structural optimization, approximations of the structural response are often developed to minimize the number of computationally expensive finite element analyses needed during the design process. In order to develop a computationally tractable design framework it was essential to develop an effective approach to approximate the response of variable stiffness structures. The development of a generic conservative convex separable approximation specifically for composite structures and its implementation within a design framework using lamination parameters is presented in this thesis. The developed convex conservative separable approximation, following Svanberg (2002), has two parts, the first part is to ensure that the function value and the gradient of the approximation meet those of the original function, while the second term is used to control the overall approximation conservativeness and convexity by appropriately scaling this term after each successive design iteration. The approximation is expressed directly in terms of the laminate stiffness matrices, known from classical lamination theory, and is therefore independent of the chosen laminate parameterization scheme. A function approximation is generated by expanding the function linearly and/or reciprocally with respect to the laminate stiffness matrices, similar to the traditionally used conservative approximation. Instead of using derivative information to determine which terms are expanded linearly and which terms are expanded reciprocally, physical insight into the response being approximated is used to guarantee convexity by expanding the non-convex terms linearly. Using lamination parameters to parametrize the laminate stiffness matrices allows the convex nature of the approximation to be retained. Additionally, lamination parameters allow the laminate stiffness matrices to be expressed using a minimum number of continuous design variables, allowing efficient gradient based optimization algorithms to be used. An efficient design optimization framework, based on the aforementioned conservative convex separable approximations, is developed and enables the solution of variable stiffness design optimization problems with several thousand design variables. The optimizer consists of three loops, one, a convergence control loop, two, a global optimization loop, and three, a local optimization loop, where the latter two loops correspond to the optimization problems that result when using the dual method. The convergence control loop is used to dynamically control the degree of conservativeness of the considered approximations and to decide if the optimal solution of the approximate subproblem is accepted for the following iteration. The global optimization loop consists of solving for the Lagrange multipliers associated with the constraints. The local loop is used to solve the local separable approximations iteratively in terms of lamination parameters to obtain the optimum stiffness distribution. The separable nature of the response approximations allows the local optimization problems to be solved in parallel, further reducing computation time on multi-processor computer systems. Typically, less than thirty finite element analyses are required to converge to the optimal solution of a problem with several thousand design variables and several hundred constraints, while roughly 80-90% of the performance gains are typically achieved within the first 3-5 design iterations. One of the limitations, and perhaps objections to using lamination parameters for composite design, has been the difficulty of incorporating strength constraints into the optimization process. In order to facilitate the acceptance of the approach, a method of including the Tsai-Wu strength criteria in the most general setting is developed. Analytical expressions for conservative failure envelopes in terms of two strain invariants are derived that are no longer an explicit function of the laminate stacking sequence. The derived envelope is shown to accurately represent the factor of safety for practical laminates under in-plane loading, however, for bending dominated problems it may be too conservative. A failure index is subsequently defined and used to formulate an optimization problem to design laminates for maximum strength under combined axial and shear loads. The designs are subsequently compared to the equivalent maximum stiffness designs. Strength-optimal and stiffness-optimal designs for various materials and load conditions are obtained and are found to be similar for a large range of problems. However, differences were also found, particularly for compression-shear loaded panels. Laminate strength is found to be significantly more sensitive to the final laminate design than laminate stiffness, which implies that design for maximum strength will result in near-optimal laminate stiffness, however, the opposite is not necessarily true. Approximations for several specific design optimization problems related to buckling are developed. Initial work is focused on developing convex separable approximations of the buckling load of plates. It is shown, using the eigenvalue problem used to solve for linear buckling, that a homogenous convex approximation for the inverse buckling load factor is obtained when expanding the geometric stiffness matrix linearly in terms of the laminate in-plane stiffness while expanding the material stiffness matrix reciprocally in terms of laminate bending stiffness. A convex approximation to maximize laminate stiffness is also developed. A trade-off study between maximum laminate stiffness and maximum laminate buckling load of a plate under uniaxial compression is conducted. Numerical results demonstrate that significant improvements in structural performance are possible and that a variable stiffness laminate with overall stiffness equivalent to a quasi-isotropic laminate can be designed to have twice the buckling load. In-plane load redistribution is found to be the primary mechanism resulting in improved buckling load and post-buckling analysis demonstrated that variable stiffness laminate designs have similar or superior post-buckling stiffness when compared to the equivalent constant stiffness solutions. A simplified method of including thermals stresses during the buckling design optimization process is also developed, since the pre-buckling stress state significantly influences a panels buckling behavior. For the plate buckling problem under consideration, residual thermal stresses are shown to beneficially influence the compressive load carrying capacity of a plate if the temperature difference between curing temperature and operating temperature are not excessive. The range of operating temperatures over which a panel exhibits good buckling behavior increases significantly when including thermal effects in the design process. Later, the approximation of the inverse buckling load factor is extended to include laminate thickness as a design variable, which requires additional linearization of the terms linear in the laminate stiffness matrices. Compared to the optimal variable stiffness design with constant thickness further improvements in the buckling load, 30-100% depending on the minimum bound thickness, are obtained. When thickness variation is included in the variable stiffness design routine for maximum laminate buckling load, both load redistribution and increased laminate bending stiffness are found to play a role in the improved structural performance. Using the insight gained from studying variable stiffness plates, a convex approximation of the inverse buckling load for general structures is derived. Convexity of the approximation is guaranteed by expanding the terms associated with the geometric stiffness matrix linearly with respect to the laminate stiffness matrices and expanding the terms associated with the material stiffness matrix reciprocally. An example problem, a curved panel subject to a uniform pressure load, is presented to demonstrated the applicability of the derived approximation. Two practical design applications are studied with several industrial partners to demonstrate the effectiveness of the developed design approach. A first problem considers the design of a simplified window belt section for maximum tensile strength. Numerical results highlight that variable stiffness laminates, including manufacturing constraints, can be found that have a 50% higher failure load compared to the best constant stiffness design. A second design problem focuses on the design of an aircraft wing rib to meet a range of imposed design requirements with buckling as a primary design driver. Other than demonstrating the benefit of using stiffness variation for more practical structures, the analysis for this design problem is conducted entirely using an external commercial finite element solver. Also for this more practical design problem the optimizer was found to perform satisfactorily.","Variable Stiffness; Optimization; Composite; Automated Fiber Placement; Buckling; Lamination Parameters; Laminate Strength","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Computational Mechanics Group","","","",""
"uuid:2c91c8bd-b0a4-4c3b-86ee-f5ad8f1ea24e","http://resolver.tudelft.nl/uuid:2c91c8bd-b0a4-4c3b-86ee-f5ad8f1ea24e","Characterisation of fibre metal laminates under thermomechanical loadings","Hagenbeek, M.","De Borst, R. (promotor)","2005","Fibre metal laminates, such as Arall or Glare, can offer improved properties compared to monolithic materials. Glare for example shows improved fatigue, residual strength, burn-through, impact and corrosion properties with respect to aluminium 2024, together with a considerable weight reduction and competitive costs. A large research program has proven the technological readiness of Glare and the fibre metal laminate has seen its application today in the primary structure of the Airbus A380 super jumbo. However, the effect of temperature on the performance of the fibre metal laminates has not been fully characterised. Differences in thermal expansion coefficients cause residual stresses after curing of the laminate. In service the temperature of the aircraft skin can vary between -55 up to 70 C due to solar radiation and convection, which will affect the thermal and mechanical properties of Glare. A detailed understanding of the behaviour of these laminates is necessary for further improvement of their performance and durability. With the increase in complexity of structures and material systems, the need for powerful design tools becomes evident. In this thesis, the thermo-mechanical behaviour of fibre metal laminates has been characterised via experimental testing and numerical modelling. Experimental tests have been performed to determine the temperature-dependent thermal and mechanical behaviour of unidirectional (UD) glass-fibre epoxy. Calculations based on these test results at room temperature and 80 C for the tension and shear stiffness of three different composite laminate lay-ups showed a good agreement with experimental test results. The UD glass-fibre epoxy data is used as input for the finite element model, together with aluminium 2024-T3 data from the literature. Glare laminates with a special lay-up have been experimentally tested to determine the effect of temperature and mechanical loadings on the laminate characteristics. The test results show that the off-axis and temperature effect can give a reduction of 24% in ultimate strength at room temperature due to off-axis loading and a further reduction of 17% at 80 C temperature. For standard Glare from the literature, where tests at elevated temperature have only been performed in fibre direction, the strength and stiffness reductions are at most 12% compared to room temperature. Numerical simulation is a very powerful tool to investigate the behaviour of materials and structures. Therefore, a thermo-mechanical finite element model, based on a solid-like shell element and including thermal expansion and heat transfer, has been developed to capture the behaviour of Glare in a fully three-dimensional state. The through-the-thickness temperature and stress distributions can thereby be determined, which allows for a straight-forward implementation of damage and plasticity models. Moreover, the solid-like shell element is ideal for thin-walled (aerospace) structures since it can have high aspect ratios without showing Poisson thickness locking, which occurs in standard continuum elements, and can have multiple layers in one element. To account for physical nonlinearities, a strain hardening model for the aluminium 2024-T3 and an orthotropic damage model for the UD glass-fibre epoxy layers in Glare are used. The strain hardening behaviour of aluminium has been modelled with a yield function based on an isotropic Von Mises plasticity formulation. An exponentially saturating hardening law has been assumed, which gives a good agreement with the experimental aluminium 2024-T3 stress-strain curve. A return-mapping algorithm is used to project the stress back onto the yield surface when the stress state violates the loading condition. The concept of continuum damage mechanics is used, with a separate damage parameter for fibre and matrix, to describe the appearance of microcracks that lead to ultimate failure. The equivalent strain measure is obtained by rewriting the yield function of the orthotropic Hoffman plasticity model into a strain-based format. The damage parameters are directly implemented into the stiffness matrix to avoid undesirable coupling terms in the damage matrix. The simulations of the shear and tensile test in transverse direction show a good fit with the experimental curves for the UD glass-fibre epoxy. The transient behaviour is captured by taking the heat capacity, inertia forces and damping into account. Park's method is used to solve the dynamic system of equations. The good performance of the thermomechanical solid-like shell element and the transient solver have been demonstrated for a single element under thermo-mechanical loadings and the snap-through of a cylindrical panel subjected to a concentrated load. Via a number of benchmark tests for practical applications the obtained numerical model is compared with the experimental test results. Bluntnotch test simulations have been performed on Glare3-3/2-0.4 and on a special Glare laminate (tested at 0, 45, 67.5, and 90 off-axis angle), which show a good agreement with experimental results. Simulations of off-axis tensile tests on a 0/90 composite, tensile tests on standard Glare laminates, and off-axis tensile tests on special Glare laminates with additional fibre layers in -45 and 45 direction, also showed a good agreement with experimental results. The thermo-mechanical solid-like shell element and the experimentally obtained material data, presented in this thesis, together create a powerful simulation tool for the effective and accurate characterisation of fibre metal laminates under thermo-mechanical loadings.","fibre metal laminates; thermo-mechanical; numerical modelling; experiments; glass-fibre epoxy; damage; plasticity; temperature; off-axis effects","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:935d7dc4-343e-466f-97f3-9a140445e541","http://resolver.tudelft.nl/uuid:935d7dc4-343e-466f-97f3-9a140445e541","Estimation of Composite Hydrodynamic Roughness Over Land with High Density Airborne Laser Scanning","Rahman, M.Z.A.","Menenti, M. (promotor); van de Giesen, N. (promotor); Gorte, B.G.H. (promotor)","2011","","Airborne LiDAR; Composite hydrodynamic roughness","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:c0cb51f7-dc9f-418e-b80d-a312e9f3b6b5","http://resolver.tudelft.nl/uuid:c0cb51f7-dc9f-418e-b80d-a312e9f3b6b5","Aero-elastic Stability Analysis for Large-Scale Wind Turbines","Meng, F.","Van Tooren, M.J.L. (promotor)","2011","Nowadays, many modern countries are relying heavily on non-renewable resources. One common example of non-renewable resources is fossil fuel. Non-renewable resources are ?nite resources that will eventually dwindle, becoming too expensive or too environmentally damaging to retrieve. In contrast, renewable energy resources, like wind energy, are constantly replenished and are important because of the bene?ts it provides for us as well as for our environment. However, getting the energy from wind must be further investigated in order to make the usage of wind energy more economically. During the past thirty years, the trend in wind energy is to increase the size of wind turbines for producing more electricity power with lower cost. The increase in size is bene?cial in terms of reduction of manufacturing costs per kW hours and reduction of the ground surface occupied by the wind farms. Further increases in size are not easily achievable because designers are expected to face more unknown technical problems such as aero-elastic stability problems. Therefore, it is important to investigate the aero-elastic stability problem of each new design concept in order to prevent the damage happen. In practice the larger blades have a lower edge-wise frequency that is closer to the ?ap-wise frequency than the case for the smaller blades. This could result in bigger edge-wise vibrations and unexpected aero-elastic problems. Larger blades will also result in large deformations even when the wind turbines are running at the design condition. Furthermore, designing pitch-regulated wind turbines will often result in lightweight and very ?exible blades. The effects of large and ?exible blade are mainly reducing diameter of the rotor during operation and coupling between edge-wise and torsional forces and motion. Most aero-elastic codes for wind turbines do not consider the e?ects of large de?ections in their simulation of the loads and responses. The reduced effective rotor area leads to lower power production than predicted by linear calculations and the coupling between edge-wise and torsional forces and motion will increases pitch moment at the blade pitch system. The problems mentioned above are the current research problems needed to be investigated and solved due to upscaling of the wind turbines. In this research work, nonlinear ?exible multi-body dynamics has been chosen to couple with nonlinear aerodynamics to investigate the current research problems mentioned before. An aero-elastic simulation tool called MBDyn-AeroDyn is developed by integration of two existing code named MBDyn [1] and AeroDyn [2]. MBDyn is a nonlinear ?exible multi-body dynamic code, which can simulate the effect of large de?ections and large rotations. The aerodynamic forces acting on wind turbine blades are calculated using AeroDyn which is based on the blade element-momentum theory. Improvement of aerodynamic calculation has been made by adding a modi?ed Pitt-Peters dynamic in?ow model in AeroDyn. Afterwards, both a linear time invariant system identi?cation method and a linear time periodic system identi?cation method have been used and implemented to investigate the aero-elastic stability of multi-MW wind turbine blades. Finally wind tunnel measurements have been performed in order to validate the aero-elastic simulation tool developed in this work. The validation of this aero-elastic simulation code has been carried out in this thesis. The time domain simulation results show that this aero-elastic simulation tool has good agreement with wind tunnel experiment results at the design operation condition. For the offdesign cases, the differences become larger gradually. Further more, an aero-elastic simulation has been applied on a 5MW wind turbine. Comparison has been made between FAST and BLADMODE in time domain. The results show that MBDyn-AeroDyn and FAST have a good agreement for an uniform wind ?eld. Finally, ?ap-torsion ?utter analysis on the 5MW wind turbine has been performed. The main feature of this aero-elastic simulation tool for multi-MW large horizontal axis wind turbines developed in this work is that kinematically large displacements and rotations are included, and that loads are applied on the deformed geometry. This allows the designers to simulate large wind turbines with more ?exible blades to capture the effect of large displacements and rotations more accurately. Another feature is that both a linear time invariant system identi?cation method and a linear time periodic system identi?cation method have been implemented. It allows the designers to analyse stability from the time domain simulation data. From the result of ?ap-torsion ?utter analysis on the 5MW wind turbine, it is shown that ?ap-torsion ?utter is not likely to occur on this 5MW wind turbine with the current blade structural properties and intended operating conditions. Considering with the current Ph.D works which have been done so far, ?rstly, another wind tunnel experiment maybe necessary by using the same blades. Future measurement should be made at a higher rotation speed and combined with higher wind speed in order to ?nd the stability boundary of this model wind turbine. Secondly, this aero-elastic simulation tool should be integrated into a knowledge based engineering(KBE) wind turbine blades design environment in order to take advantage of this aero-elastic simulation tool. Further research work should be carried out to simulate wind turbine blades with smart control devices, for example, ?aps on the blades. Last but not the least, an user friendly graphical interface for this tool should be made in order to make it more convenient to use for a wider group of users.","wind turbine simulation; aero-elastic; stability","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration & Operations","","","",""
"uuid:7b2d141e-3c9e-4645-9190-26a9f3d98957","http://resolver.tudelft.nl/uuid:7b2d141e-3c9e-4645-9190-26a9f3d98957","Identification and Modeling of Sea Level Change Contributors: On GRACE satellite gravity data and their applications to climate monitoring","Wouters, B.","Ambrosius, B.A.C. (promotor)","2010","Since early 2002, the Gravity Recovery and Climate Experiment (GRACE) twin satellite mission provide the scientific community with accurate monthly maps of the Earth's gravity field. On short time-scale, the observed variations are mainly related to a redistribution of water on the Earth's surface. This new data set has lead to a leap forward in our understanding of the various components of the Earth's water cycle, and their mutual interaction. The GRACE data provided by the science teams are contaminated by noise, hampering the interpretation of the observations. The first part of this thesis describes a statistical filtering method which removes the majority of the noise and allows utilization of the GRACE data at their full potential. Using the filtered observations, variations in the water budget of the climate system have been studied. A method was developed to obtain a picture of the mass balance of the Greenland ice sheet at a regional scale. From the research in this dissertations, it shows that Greenland lost about 200 cubic kilometers of ice each year on average between 2003 and 2008, causing a global mean rise of sea level by 0.5 mm/yr. An acceleration of the thinning of the ice sheet is observed, with a contribution of 0.75 mm/yr to global mean sea level rise in the last two years. Furthermore, the GRACE observations have been used to identify the seasonal exchange of roughly three thousand gigatons of water between land and ocean, and, in combination with sea level measurements from altimeter satellites, to constrain the cycle in heat content of the ocean. Finally, a method was developed to model the passive adjustment of the sea level to changes in the gravity field of the earth, induced by mass redistribution on the continents. Including this 'selfgravitation effect' into numerical ocean model would result in a better agreement between modeled and observational ocean data in several regions.","sea level; climate; GRACE; Greenland; ocean; satellite gravity","en","doctoral thesis","","","","","","","","2010-01-19","Aerospace Engineering","Department of Space Engineering","","","",""
"uuid:9a9a60c1-893f-4c1a-9873-2c1735e58b9c","http://resolver.tudelft.nl/uuid:9a9a60c1-893f-4c1a-9873-2c1735e58b9c","Holographic Interferometric Tomography for Unsteady Compressible Flows","Timmerman, B.H.","Bakker, P.G. (promotor)","1997","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5ae43ed1-345f-423a-8285-d151e9bd34d0","http://resolver.tudelft.nl/uuid:5ae43ed1-345f-423a-8285-d151e9bd34d0","Sandwich fuselage design","Van Tooren, M.J.L.","De Jong, Th. (promotor)","1998","","sandwich; fuselage; composite","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5a126ea6-74fc-4678-b84c-18ca3fd962c5","http://resolver.tudelft.nl/uuid:5a126ea6-74fc-4678-b84c-18ca3fd962c5","Multi-point aerodynamic design by optimization","Soemarwoto, B.I.","Slooff, J.W. (promotor)","1996","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ee47629a-892b-4463-9543-586ce6fe1ef2","http://resolver.tudelft.nl/uuid:ee47629a-892b-4463-9543-586ce6fe1ef2","Aeroelastic Loads Modeling for Composite Aircraft Design Support","Baluch, H.A.","Van Tooren, M.J.L. (promotor)","2009","With regard to the simulation of structural vibrations and consequent aeroelastic loads in aircraft components, the use of elastic axis e.a as reference of vibrations is quite common. The e.a decouples the bending and torsion degrees of freedom (D.o.F) during the dynamic analysis. The use of the e.a to decouple the bending and torsion in vibration analysis does not work for fiber composite structures with anisotropic material properties. Anisotropic material properties often result in an elastic axis that is either discontinuous or far outside the real aircraft. Existing mathematical models of exible aircraft dynamics do not address this issue. In this report, state of the art inertially coupled equations of motion of a flexible aircraft are modified. For each of the equivalent beam model of the fuselage, wings, and tail structure a particular fixed reference axis r.a is used for vibrations instead of elastic axis. Since no decoupling can be used, the beam deflections become a function of both bending and twist. The resulting displacements are expanded to the expressions of beam generalized velocities. Apart from the inclusion of the coupling effects, it is also thought to modify the structural dynamics model that, apart from the conventional tail configuration, should also accommodate the analysis of T-Tail configuration aircraft. These developments modify the expressions of kinetic and strain energies and subsequent global mass and stiffness matrices, state-space coeffcient matrices. The modified model is then linearized into zero-order problem (i.e. rigid-body maneuvers) and first-order problem (i.e. vibrations and their effects on the rigid-body response of the aircraft). The equations of motion are then expanded to the structural loads equations, which are based on the summation of forces method (SFM) and mode displacement method (MDM). SFM is based on the summation of all the aerodynamic, gravity, and inertial forces on a component. Whereas the MDM is based on the structural deformations caused by the external forces. The results computed from SFM can be verified by comparing to those of the results from the MDM. A computer code, DARLoads, is written to simulate the dynamics of the flexible aircraft and all the equations given in this report are programmed in MATLAB software. An executive twin-jet is selected for the simulation. Due to the nonavailability of the composite aircraft data the coupling effects on the response of the aircraft are studied by manipulating the e.a of each wing and horizontal tail of the metal aircraft in five different cases of numerical examples. In first three cases, the e.a of each wing and horizontal tail is drawn parallel to the r.a of that particular component, where the e.a with respect to r.a of each component is placed in three different positions. In the fourth and fifth case, the e.a of each wing and tail is drawn by intersecting the shear centers of each section from root to tip. The aircraft is trimmed at the given air speed and altitude for each e.a case, which shows that the coupling affects the trim variables significantly (i.e. elevator and thrust inputs, and the pitch angle) and moreover the static deflections. For each optimized trim condition the aircraft is subjected to different dynamic conditions, which include the discrete gust and abrupt checked elevator maneuver with a conventional tail configuration, and impulse aileron input with a T-tail configuration. The results in the form of rigid-body response and consequent structural loads show the same kind of scenario as observed in the static case (i.e. during trim solution). It shows that the position of elastic axis has significant effects on the dynamics of the fully flexible composite aircraft.","flexible aircraft; fiber composite airframe; dynamic loads; coupled vibrations; equations of motion; elastic axis; summation of forces; mode displacement","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration & Operations","","","",""
"uuid:c0b3d6bc-9f30-420d-acc3-c2e542c529dd","http://resolver.tudelft.nl/uuid:c0b3d6bc-9f30-420d-acc3-c2e542c529dd","Development of a fast shape memory alloy based actuator for morphing airfoils","Lara-Quintanilla, A.","Benedictus, R. (promotor); Bersee, H.E.N. (promotor)","2016","The design of aerodynamic airfoils are optimized for certain conditions. For instance, the shape of the wings of fixed-wing aircrafts are designed and optimized for a certain flight condition (in terms of altitude, speed, aircraft weight, etc.). However, these flight conditions vary significantly during the flight. Currently, aircraft are provided with control surfaces such as flaps, slat and ailerons, normally governed by powerful but heavy hydraulic mechanisms. These moving parts allow the aircraft to fly under many different flight conditions, although usually with non-optimal performance. Moreover, these mechanisms introduce hinges and surface discontinuities between parts which cause undesirable effects such as turbulences and noise or a decrease of the lift-to-drag ratio. This issue motivates the research and development of the so-called ‘morphing aircraft’ or ‘morphing wings’. Ideally, a morphing aircraft is able to modify quickly the shape of its wings in-flight, thus reaching optimum aerodynamic performance under any flight condition. This idea is applicable to any other aerospace applications such as rotorcraft or wind turbines. Morphing applied to aerodynamic airfoils brings along interesting benefits: reduction of mechanical fatigue which has a special importance in wind turbines and rotorcrafts (by minimizing vibrations on the structure), reduction of the wing root bending moment, reduction of fuel consumption of flying machines and increase of the performance of wind turbines by increasing the lift-to-drag ratio of the wings or blades, and the reduction of generated noise. This dissertation gives an introduction on the concept of morphing applied to aerodynamic airfoils and describes the benefits and challenges brought by morphing structures. Subsequently, the potential of smart materials to develop novel actuation systems is introduced. The description of the motivation for this work leads to the purpose of this research, which aims at developing a prototype of a general-purpose morphing flat surface based on embedded shape memory alloy wires with increased working frequency for morphing airfoils. In order to achieve this purpose, the research is divided into two research objectives. The first research objective is to develop a profound understanding of the behaviour of shape memory alloys (SMAs) and, subsequently, to devise a method to increase their actuation frequency. The second research objective is to develop novel control algorithms and actuator technology as well as an integration technology for the SMA wires with increased actuation frequency. Following the introduction, this thesis describes the potential of smart materials in general, and SMAs in particular, to develop novel smart actuators for morphing wings. The main differences between conventional and smart actuators are explained together with their advantages and introduced challenges in terms of design and control. The selection of SMAs is justified as the best candidates to achieve the research objectives. A detailed description, working principles, features, capabilities, limitations and applications of SMA based actuators is given as well. In order to fulfill the first research objective, a series of logical steps were followed. Once the requirements of the SMA based actuator were stated, a commercial SMA wire was chosen and characterized (i.e., the phase diagram of the SMA wire was obtained) which shows the phase composition of the SMA when it is subjected to different levels of stress and temperature. The phase diagram was obtained from data collected from isothermal, isobaric and differential scanning calorimeter tests. During an isothermal test, the temperature is kept constant and the SMA wire is subjected to increasing and decreasing levels of stress in order to find those stresses at which the SMA’s phase transforms. Similarly, an isobaric test keeps the stress on the SMA constant over time and the temperature is increased and decreased to find those at which the SMA’s phase transforms. Subsequently, the functional fatigue of the SMA wire was studied by training the SMA wire. This training process consist in applying repetitive heating and cooling cycles in an isobaric configuration. High repeatability was found on the results. After an average of 7289 training cycles, the wire was able to recover only 77% of its original recoverable length for the tested conditions of applied current, heating time, cooling time and applied stress. Subsequently, an SMA model for SMA wires is implemented in a finite element analysis software. The equations that describe the model and their physical meaning are explained. One of the advantages of the chosen model is the ease of obtaining the parameters required by the model, which can be obtained from a few experiments. In addition, and also as a part of the model’s required parameters, the characteristics of the forced cooling system are studied here, and the heat transfer coefficient of such airflow for different airflow rates is measured. Finally, the model is satisfactorily validated. One of the limitations of SMA based actuators is their poor actuation frequency (usually lower than 0.1Hz). This is due to the fact that they are thermally activated, normally by Joule heating, which is a quick process. However, they must be cooled before the next actuation cycle, which normally happens by natural convection. This cooling process can be accelerated by means of active cooling systems. In this research, an active cooling airflow at room temperature is used. The effects of applying different heating and cooling rates on the time that it takes for the wire to contract and elongate (respectively) were experimentally measured using an isobaric configuration. In addition, the same experiments were simulated by the model for SMA wires implemented previously. There is an overall quantitative disagreement between the results yielded by the simulations and by the experiments. However, the results are useful qualitatively. It is found that the contracting and the cooling times are significantly decreased as the applied power and airflow is increased. More importantly, it is found that when the wire works at low working frequencies, the heating rate is the limiting factor whereas the cooling rate is the limiting factor when it works at high working frequencies. In addition, these experiments show that increasing the level of applied stress results in slightly higher working frequencies of the SMA wire. The knowledge acquired in the previous experiments and simulations leads to the development of a method to improve the attainable actuation frequency of the SMA wires. This method is based on the idea that, in many SMA based applications, the SMA wires do not work throughout their full recoverable strain but they work only within a portionofit. Taking advantage of the nonlinearity of the strain-temperature relationship for SMAs, the method proposed here is able to increase the SMA’s actuation frequency by three and a half times just by making the SMA wire work within the most suitable range of strains, without varying the heating, cooling and stress conditions. The development of this method fulfills the first research objective. Later on in this thesis, the design, manufacturing and assembling processes of the SMA based actuator as well as their challenges are detailed. First, a beam-like module of the SMA based actuator was conceived, designed and manufactured. Subsequently, the design was expanded in the spanwise direction, thus obtaining a modular SMA based actuator that forms a morphing plate. The morphing plate was tested by heating the SMA wires embedded in the actuator. This test revealed an unexpected behaviour of the plate. The expected behaviour was that it would bend upwards when the wires on the top side were heated. However, instead of bending uniformly along the spanwise direction, the center of the plate bended upwards and the sides downwards. A similar response was observed when the wires on the bottom side were heated. This was found to be caused by inhomogeneous thermal expansion (in the spanwise direction) through the thickness of the plate. Due to the unexpected response observed on the morphing plate, a single beamlike module SMA based actuator was controlled under two different control strategies, fuzzy logic control (FLC) and proportional-integrative-derivative (PID) control. In both cases, the SMA based actuator was made to track sinusoidal and step signals in order to measure its performance. The overall performance of the system under FLC is better than that under PID. Under FLC, it reaches actuation frequencies above 0.6Hz for working at amplitudes of up to 6mm, and frequencies above 1Hz for amplitudes of up to 3mm while tracking the reference signal accurately (maintaining relative error below 10%). Under PID control, it reaches actuation frequencies above 0.5Hz when working at amplitudes up to 3mm, and frequencies above 0.7Hz for amplitudes up to 2mm. The actuator is able to track step signals (that is, to reach and maintain a constant deflection over time) under both types of controller, although under FLC it is significantly more stable. These developed design, manufacture, assembly and control methods fulfill the second research objective. This thesis presents novel methods aiming to increase the accuracy and actuation frequency of SMA based actuators. In particular, this work is focused on the development of a morphing surface intended to be integrated in morphing airfoils. However, the methods and ideas developed in this research are applicable to other SMA based applications, especially those which require fast, cyclic and accurate actuation.","shape memory alloy; actuator; actuation frequency; control; morphing airfoils","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Structural Integrity and Composites","","","",""
"uuid:67fa0d80-98a9-4041-8d68-29a3ada4bd2a","http://resolver.tudelft.nl/uuid:67fa0d80-98a9-4041-8d68-29a3ada4bd2a","Conformable Pressurized Structures: Design and Analysis","Geuskens, F.J.J.M.M.","Beukers, A. (promotor)","2012","There are many applications where volume needs to be pressurised within a geometrical space for which conventional pressure vessels do not provide suitable solutions. Applications are for example found in pressure cabins for Blended Wing Body Aircraft and conformable pressure vessels for an incompressible medium that has to be stored in a pressurised environment, specifically liquid gasses (e.g. propane) or cryogenic applications. These applications demand conformable pressurised structures but up until now, there are no conformable pressurised structures with full spatial freedom, made from high specific strength materials and optimal structural efficiency realised yet. The aim of this thesis is to provide understanding in the analysis and structural design of conformable pressurized structures. This thesis will enable the development of conformable pressure cabins and pressure vessels. From a structural topology point of view, efficient structures are in-plane, rather than out-of-plane, loaded structures. In this thesis, it is shown by means of linear membrane analysis that any arbitrary combination of intersecting axi-symmetrical membrane structures will always carry the pressurization loads via in-plane stresses provided that there is a proper in-plane loaded reinforcement at the surface of intersection. The most well-known example of a structure like this is a cluster of soap bubbles. In this example, the axi-symmetrical membrane structure is a sphere and the intersecting walls are the in-plane loaded reinforcements. This type of conformable pressure vessel is therefore called the multi-bubble. Simple shapes like intersecting spheres, intersecting cylinders or intersecting toroids are easy to analyse but the analysis becomes complex when different types of axi-symmetric elements are intersecting each other. This problem has been tackled by the visual interpretation of the linear membrane theory. To solve for loads and forces in the multi-bubble, it is shown that the solution simply depends on pressure and geometric variables. The solution is only valid however when the shell has the optimal stiffness distribution. The optimal stiffness distribution causes the inflated shape to be identical to the original shape, only the size is different. The optimal stiffness distribution is derived in this thesis. Manufacturing restrictions and cost limitations might cause the optimal stiffness distribution not to be economically feasible. A non-optimal stiffness distribution causes a nonlinear membrane response. A modified linear membrane solution for orthotropic membranes is derived in this thesis to solve for forces and deformations in non-optimal membranes. Furthermore, the understanding of the membrane response of pressurised structures also enables the formulation of a tailored stiffness distribution in order to control/eliminate deformations in particular directions. This can ease the integration of the pressurized structure in the surrounding structure. The achievements of this research can be summarized into: . Provision of a deeper understanding of the shape of (conformable) pressurized structures . Development of the method to analyse the forces at the surface of intersection of the intersecting membrane structures . Definition of the optimal stiffness distribution in order to derive the desired membrane response. . Formulation of a tailored stiffness distribution in order to control/eliminate deformations in particular directions. This can ease the integration of the pressurized structure in the surrounding structure. . Formulated the orthotropic version of the modified linear membrane theory in order to analyse the nonlinear membrane response in case the membrane’s stiffness distribution differs from the optimal distribution. . Presentation of conceptual ideas of conformable pressurized structures applied to pressure tanks and pressure cabins.","conformable; multi-lobe; multi-bubble; pressure vessel; pressure tank; pressure cabin; pressure fuselage; Blended Wing Body; cryogenic tanks; modified linear membrane analysis; CHATT","en","doctoral thesis","Uitgeverij BOXPress, 's-Hertogenbosch","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:7e920384-911b-4759-a0ef-a169fe55779f","http://resolver.tudelft.nl/uuid:7e920384-911b-4759-a0ef-a169fe55779f","Semi-analytical long-arc satellite orbit computation and the estimation of time-varying gravity parameters","Bruinsma, S.L.","Wakker, K.F. (promotor)","2003","","orbit computation; perturbation modelling; parameter estimation","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:80e11dbd-90be-44f1-bb36-049503a265bd","http://resolver.tudelft.nl/uuid:80e11dbd-90be-44f1-bb36-049503a265bd","A perturbation approach for geometrically nonlinear structural analysis using a general purpose finite element code","Rahman, T.","Gurdal, Z. (promotor)","2009","In this thesis, a finite element based perturbation approach is presented for geometrically nonlinear analysis of thin-walled structures. Geometrically nonlinear static and dynamic analyses are essential for this class of structures. Nowadays nonlinear analysis of thin-walled shell structures is often done using finite element based incremental-iterative procedures. However standard finite element based nonlinear analysis of many practical structures is still computationally expensive and not suitable for repeated runs necessary for a design and optimization process, and also the interpretation of the results can be difficult. Koiter introduced a perturbation approach where a perturbation expansion for the load and the displacement field are made around a known state (e.g. a bifurcation buckling point) to capture the essential nonlinear behavior of the structure. The final outcome is a computationally inexpensive reduced order model providing a good insight into the structural behavior in terms of the postbuckling a and b coefficients and the first order (the buckling modes) and the second order modes. Therefore, application of Koiter’s perturbation approach within a finite element framework can support standard nonlinear analysis by providing an effective solution to the aforementioned problems. The main focus of the present research is on the extensions which are necessary for this application The aim of the present research is to show the feasibility of implementing the perturbation approach in a general purpose finite element code in order to handle practical shell structures. In accordance with this perspective, the implementation of the present work is done in the development environment of a general purpose finite element code (DIANA) so that practical problems can be addressed. A general framework for the finite element implementation of Koiter’s perturbation approach is already available in DIANA. The present implementation makes use of that framework and does the necessary extensions. Two key aspects in this research are the inclusion of the effect of prebuckling nonlinearity and consideration of composite shells. Inclusion of the effect of prebuckling nonlinearity makes it possible to handle an important class of problems consisting of axially loaded cylindrical and conical shells where the prebuckling nonlinearity has a large influence on the buckling and postbuckling behavior. The implementation of the perturbation approach is done for a class of Mindlin type curved beam and shell elements and a Kirchhoff type triangular flat shell element. The present thesis contains a part on static problems and a part on dynamic problems. In the part on static initial post-buckling problems, first the perturbation method is explained within the single mode context (considering one buckling mode), including prebuckling nonlinearity and its finite element implementation. The special case of a linear prebuckling state is also discussed. Various reference problems consisting of both isotropic and composite shells are considered. The postbuckling coefficients are compared with available results in literature and semi-analytical results. In all cases a reasonable agreement in the buckling and second order modes and the postbuckling coefficients is obtained. In case of the benchmark conical shell problem (representative of the 1/2 interstage of the Vega launcher) initial postbuckling response (based on single mode analysis) obtained using the present approach compares reasonably well with the full model analysis. A comparison of computational time with full model analysis shows the significant gain achieved in computational cost with the present approach. The locking problem in the determination of postbuckling b coefficient is an important issue in the implementation of the perturbation approach in a finite element context. It is found that the Mindlin type shell and beam elements that are used in this research (where both in-plane/axial and out-of-plane/lateral displacements are interpolated independently) do not show the locking problem with respect to convergence of the b coefficient. Next, in order to study modal interaction effects, the necessary extensions needed for multi mode analysis (in which more than one buckling mode is considered) are discussed. Considering a large number of modes in the perturbation analysis is computationally expensive. Therefore, a guideline is proposed for the selection of appropriate modes based on the minimum direction (the direction that leads to the steepest descent or the smallest ascent of the total potential energy in the buckling space) and uncoupled postbuckling coefficients (postbuckling coefficients associated with a single specific mode) and demonstrated using appropriate examples. Also, industrial benchmark problems consisting of a curved and a flat stiffened CFRP panel are considered. A reasonable agreement in the results is obtained in both cases. The efficiency of the reduced order model is also demonstrated by comparing the computational time with full model analysis. Finally, as a specific application, axially loaded, variable stiffness composite panels are considered and the potential of the perturbation approach in the optimization process for the improvement of postbuckling performance of such panels is demonstrated. The expressions for in-plane postbuckling stiffness for plates under axial compression is derived both for the single mode and the multi mode case. In a specific multi mode case where clustering of buckling modes appears, the minimum direction or the worst direction (in the buckling space) of the structure are determined for the initial postbuckling regime and the resulting postbuckling stiffness is computed. It is found that the panels considered having two nearly coincident buckling modes show the lowest postbuckling stiffness if they buckle in a shape with two half waves. This can be explained in terms of the second order stress distribution over the panel. It is an instance showing the type of insight one can gain about the structural behavior using the perturbation approach. It is also found that a compromise between buckling load and prebuckling stiffness may yield a better performance with respect to ultimate load (the failure load, in this case assumed to correspond with the onset of material degradation) and limit load (the maximum load that the structure can encounter during its operating life) compared to only buckling dominated design. Up to limit load level good agreement is obtained between the full model and the reduced order model analysis. In the part of the thesis about dynamic problems, the perturbation approach developed earlier for static postbuckling problems is extended for handling dynamic problems by taking inertial terms into account. Dynamic buckling and nonlinear free vibration problems are considered. A reasonable agreement in the prediction of the dynamic buckling load is achieved when compared with full model transient analysis. The gain in computational cost is shown for a representative case. In case of the nonlinear vibration problems, second order vibration modes, the dynamic b coefficients and the resulting backbone curves compare reasonably well with reference results.","perturbation; postbuckling; geometric nonlinearity; finite elements; thin-walled structures","en","doctoral thesis","TUDelft, Faculteit Luchtvaart-en Ruimtevaarttechiek","","","","","","","","Aerospace Engineering","Group of Aerospace Structures (AES)","","","",""
"uuid:b5aa165b-e896-42de-b31b-80fb1e72ac24","http://resolver.tudelft.nl/uuid:b5aa165b-e896-42de-b31b-80fb1e72ac24","Tomographic particle image velocimetry and its application to turbulent boundary layers","Elsinga, G.E.","Bakker, P.G. (promotor); Scarano, F. (promotor)","2008","Tomographic Particle Image Velocimetry is a new experimental method developed to study three-dimensional motion in turbulent flows. The technique is an extension of standard PIV and makes use of several simultaneous views of illuminated tracer particles and their three-dimensional reconstruction as a light intensity distribution by means of tomography. The reconstructed tomogram pair is then analyzed by means of 3D cross-correlation returning the three-component velocity vector distribution over the measurement volume. The principles and details of the tomographic algorithm are discussed and a parametric study is carried out by to identify the most important parameters governing the experimental setup and to show their effect on the reconstruction accuracy. The capability of the technique in real experimental conditions is assessed with the measurement of the turbulent flow in the near wake of a circular cylinder. Next, this new technique has been applied to study the three-dimensional coherent structures in turbulent boundary layers. Quantitative visualizations of the individual (hairpin) vortices as well as the large-scale structures in both a low speed turbulent boundary layer and a high Reynolds number supersonic boundary layer have been obtained. The high Reynolds number data also suggests a very-large-scale flow organization exists not only in streamwise direction but also in spanwise direction. These very-large scale motions appear to consist of large-scale hairpins, which display a preferential alignment in streamwise direction and in the spanwise direction along the 45 degrees diagonal with the respect to the streamwise direction. Moreover, the time evolution of the flow structures is visualized in an experiment, in which the Tomographic-PIV technique is applied to nearly time-resolved image sequences recorded at 1.5 kHz.","piv; aerodynamics; measurement technique; turbulence; turbulent boundary layer; coherent structures","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:70d0c634-8f18-4576-96bc-1c81ebadcaef","http://resolver.tudelft.nl/uuid:70d0c634-8f18-4576-96bc-1c81ebadcaef","Advanced hot rolling strategies for IF and TRIP steels","Elsner, A.","Van der Zwaag, S. (promotor); Steinhoff, K. (promotor)","2005","Steel producers are forced to reduce the production cost on the one hand and increase the performances of the products on the other hand, to maintain or even increase their market share. A likely method to save on production costs is to cut down the rather long production chain for conventional cold rolled strip, and to substitute certain cold rolled steel grades by hot rolled steel. Certainly this can rarely be achieved for exposed parts, requiring a perfect surface finish, whereas for unexposed parts, e.g. structural components, with lower surface requirements, the use of hot strips might be a cost saving alternative. The aim of this thesis is to contribute to the understanding of the microstructure and texture development of deep-drawing steels during ferritic rolling, subsequent cold rolling and annealing on the one hand and to appraise the possible improvement of the mechanical and deep-drawing properties on the other hand. On the basis of these results guidelines for the industrial production of ferritic rolled hot strip are proposed. Furthermore, a new hot rolling strategy for the production of hot rolled low alloy TRIP steel is proposed and the development of the microstructure and the mechanical properties to be obtained are investigated in a set plain strain compression test using a hot deformation simulator.","if steel; trip steel; ferritic rolling; intercritical rolling; microstructure; mechanical properties; texture development","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7e464c8e-b295-4c61-8299-158cd354f2a9","http://resolver.tudelft.nl/uuid:7e464c8e-b295-4c61-8299-158cd354f2a9","On the calculation of stresses in pin-loaded anisotropic plates","De Jong, Th.","Spies, G.J. (promotor)","1987","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:61c20528-79d9-4722-af37-fb2774cb09d4","http://resolver.tudelft.nl/uuid:61c20528-79d9-4722-af37-fb2774cb09d4","Value-leverage by Aerospace Original Equipment Manufacturers","Beelaerts van Blokland, W.W.A.","Santema, S.C. (promotor)","2010","With the creation of new aircraft products; Embraer E-170/190, Dassault 7X, Airbus A380 and Boeing B787, aerospace original equipment manufacturers (OEMs) involve suppliers not only with the co-production of aircraft sub systems, but also with the entire development of sub systems, like fuselage and wings. Hence, the value to create and produce aircraft tends to shift for a major part from the OEM towards the suppliers. In fact, the aerospace OEM levers value on suppliers for the creation of new value, which is the subject of this thesis: “value-leverage”. Value-leverage is the capability of an aerospace OEM-company to lever value on suppliers for the creation of new aircraft by co-development and co-production. The objective of this dissertation is to measure value-leverage performance by aerospace OEMs. It is of interest to research this phenomenon of value-leverage as the aerospace industry is characterized by high capital intensiveness and development risk involved with the creation of aircraft. The principle of a “lever” is used to explain the phenomenon of value-leverage. The aerospace OEM functions as pivot, balancing demand and supply. The pivot position or value-leverage position shifts due to the down flow of value from the OEM towards suppliers. The value-leverage position of the aerospace OEM-company depends on the degree of value-leverage on suppliers on one side and the customer demand for aircraft at the other side. The goal of this research is to know if variables can be found to express and measure value-leverage by the aerospace OEM-company. By exploratory interviews in the Netherlands and literature research towards lean manufacturing, supply chain, open innovation and OEM network organisation, variables are found that express value-leverage, which are product or company level related. The variables related to product level are applied to four aircraft cases; Airbus A380, Boeing B787, Embraer-E-170/190 and Dassault 7X. The model on product level, in the form of a lever, demonstrates how to measure value-leverage by aerospace OEMs and its effects of it by plotting the value time-curve, regarding time to break-even, investment level and market impact. The company related variables, are applied to seven aerospace OEM companies: EADS, Lockheed Martin, Boeing, Embraer, General Dynamics, Northrop Grumman and Bombardier. To pre-design the value-leverage model on company level, data from aerospace OEM companies are analysed and preliminary tested in comparison with a group of automotive OEM companies to know if value-leverage is applicable to more sectors of industry. The pre-designed model shows that the value-leverage network position and performance of the aerospace OEM-company can be determined by applying the found variables.","value-leverage; aerospace; co-development; co-production; lean manufacturing; supply chain; open innovation","en","doctoral thesis","Graphicom","","","","","","","2010-10-27","Aerospace Engineering","Air Transport and Operations","","","",""
"uuid:39529293-533a-4312-9419-4fabb8480e67","http://resolver.tudelft.nl/uuid:39529293-533a-4312-9419-4fabb8480e67","Finite rotation shell theory including drill rotations and its finite element implementation.","Rebel, G.","Arbocz, J. (promotor)","1998","","shell theory; finite rotation; drill rotation; finite element method","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:79d2dc5a-9a7c-4179-a417-a50cbba2bc5f","http://resolver.tudelft.nl/uuid:79d2dc5a-9a7c-4179-a417-a50cbba2bc5f","Stochastic Surrogates for Measurements and Computer Models of Fluids","De Baar, J.H.S.","Bijl, H. (promotor)","2014","Both measurements and computer simulations of fluids introduce a prediction problem. A Particle Image Velocimetry (PIV) measurement of a flow field results in a discrete grid of velocity vectors, from which we aim to predict the velocity field or related quantities. In Computational Fluid Dynamics (CFD), the output of the computer code depends on the input parameters, and we aim to propogate the uncertainty of the input parameters or aim to determine the choice of input parameters that optimizes the output. Presently, we discuss a general framework that uses a stochastic surrogate to address the prediction problem. In flow measurement, we predict the velocity field conditional on the discrete set of PIV data. For uncertainty propagation and optimization, we construct a surrogate of the CFD output, conditional on a discrete set of solves. As a surrogate we use Kriging, derived in a Bayesian framework. This approach has two main advantages. Firstly, when adjoint-based gradient information is available from the CFD solver, the gradient information can be included in the surrogate, reducing the computational cost of higher-dimensional uncertainty propagation and optimization problems. Secondly, measurement uncertainty of PIV data, CFD output, and CFD gradient output can be represented through the likelihood: notably, PIV data can have local variations of measurement uncertainty due to imperfect experimental conditions, while CFD gradient output is often considerably noisy|to the extent of detoriating results instead of improving them when the noise is not properly accounted for. Before applying the Kriging predictor, two well-known problems are addressed. Firstly, robustness of the Kriging predictor is found not to be related to conditioning| as is often suggested|but to numerical positive definitness of part of the gain matrix. We provide analytical estimates for conditions under which the Kriging predictor is robust. Secondly, estimating the hyperparameters becomes expensive for larger data sets, such as PIV measurements. We discuss two FFT-based methods that reduce the cost of hyperparameter estimation.","surrogate model; meta model; cfd; bayes; kriging; adjoint","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:f51feb6c-6b8f-43c9-bd8f-f252889318aa","http://resolver.tudelft.nl/uuid:f51feb6c-6b8f-43c9-bd8f-f252889318aa","Damage tolerance engineering property evaluations of aerospace aluminium alloys with emphasis on fatigue crack growth","Wanhill, R.J.H.","Schijve, J. (promotor)","1995","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4992c97d-da60-4f3b-991a-b61937cd70ee","http://resolver.tudelft.nl/uuid:4992c97d-da60-4f3b-991a-b61937cd70ee","De belasting van vliegtuigen door symmetrische remousstooten","Greidanus, J.H.","Van der Maas, H.J. (promotor)","1947","","","nl","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:fd689ba2-3c5f-4e7c-9ccd-55ddbf1679bd","http://resolver.tudelft.nl/uuid:fd689ba2-3c5f-4e7c-9ccd-55ddbf1679bd","Great expectations for offshore wind turbines: Emulation of wind farm design to anticipate their value for customers","Zaaijer, M.B.","Van Kuik, G.A.M. (promotor); Van Bussel, G.J.W. (promotor)","2013","To date, the technical feasibility of making electricity from offshore wind energy has been convincingly proven. However, the current challenge is to reduce the costs of this form of energy. One of the aspects playing a role in cost reduction is the optimisation of the wind turbine. The wind turbine influences the costs of various elements of an offshore wind farm, such as the structure on which it will be built, the electrical cabling, the installation, maintenance and, last but not least, the electricity production. The extent of this influence is hard to determine during the design of the wind turbine. In this research a method is developed to assess the effects of a wind turbine on the costs and performance of an offshore wind farm. Core of the method is a software program that automatically designs a wind farm for a turbine for which the user provides the inputs. By varying the inputs, the user can find the turbine design for which the cost of energy would be lowest. The method has been tested with a case study and with industrial users. The case study shows that the method can indeed lead to a better wind turbine design and the test-users confirm the utility of the program. Using the program stimulates further cooperation between the marketing and engineering departments, which may require a different way of working for some companies. The thesis provides a more extensive summary.","wind energy; wind turbine; offshore; optimisation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","","",""
"uuid:89c2ecfe-f5f0-4a9b-b3a5-e1d48d53860e","http://resolver.tudelft.nl/uuid:89c2ecfe-f5f0-4a9b-b3a5-e1d48d53860e","Goal Adaptive Discretization of a One-Dimensional Boltzmann Equation","Hoitinga, W.","De Borst, R. (promotor); Van Brummelen, E.H. (promotor)","2011","Fluid-flow problems in the transitional molecular/continuum regime play an important role in many engineering applications. Such problems are gaining further prominence with the perpetual trend towards miniaturization in science and engineering. The numerical simulation of flows in the transitional molecular/continuum regime and the determination of macroscale quantities from such simulation poses a fundamental challenge, on account of the complexity of the corresponding model equations. The Boltzmann equation gives a description of flow problems residing in the transitional molecular/continuum regime. The thesis entitled Goal Adaptive Discretization of a One-Dimensional Boltzmann Equation concerns the efficient discretization of a Boltzmann-type equation. We present a one-dimensional Boltzmann-type equation, which shares many important properties with its conventional counterpart. Furthermore, in a series of numerical experiments we present goal-adaptive discontinuous Galerkin finite-element approximations, which show that goal-adaptive methods are potential methods for the efficient approximation of the conventional Boltzmann equation.","Boltzmann Equation; Goal-Adaptive methods; Error Estimation; Discontinuous Galerkin; Finite Element Method","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:cff83f15-89c7-4a08-adca-5874babf6473","http://resolver.tudelft.nl/uuid:cff83f15-89c7-4a08-adca-5874babf6473","Integrated design of a man-machine interface for 4-D navigation","Theunissen, E.","Van Willigen, D. (promotor); Stassen, H.G. (promotor)","1997","","man-machine interface; navigation; flightdeck; air-traffic control; avionics","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7cebd72e-37c2-4bba-8268-48aba45fa13d","http://resolver.tudelft.nl/uuid:7cebd72e-37c2-4bba-8268-48aba45fa13d","Modelling plastic deformation of metals using irreversible thermodynamics","Huang, M.","Van der Zwaag, S. (promotor)","2008","The main objective of this thesis is to provide an irreversible thermodynamics framework to describe and predict the work hardening and stress-strain phenomena occurring in single grained and polycrystalline metals. Models to quantitatively describe these are presented. Especial emphasis is placed on the understanding of the evolution of dislocations. The models are applied to pure metals and single phase alloys with FCC or BCC structures over a wide range of temperatures, strain rates and grain sizes.","dislocation density; strain hardening; irreversible thermodynamics; ultrafine grained alloys; hot rolling; adiabatic deformation; steady state","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8f8623d5-94f7-4000-8bdb-6f379bea83da","http://resolver.tudelft.nl/uuid:8f8623d5-94f7-4000-8bdb-6f379bea83da","Design of cut-outs in shell structures","Heerschap, M.E.","Rothwell, A. (promotor); Van der Schee, P.A. (promotor)","1997","","aerospace engineering; CAD; finite elements","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5fac8b3d-f771-4842-910a-ba6118bfb5cf","http://resolver.tudelft.nl/uuid:5fac8b3d-f771-4842-910a-ba6118bfb5cf","PIV-based load determination in aircraft propellers","Ragni, D.","Scarano, F. (promotor)","2012","The thesis describes the application of particle image velocimetry (PIV) to study the aerodynamic loads of airfoils and aircraft propellers. The experimental work focuses on the development of a measurement procedure to infer the pressure of the flow field from the velocity distribution obtained by PIV velocimetry. The technique offers important advantages in aircraft propellers, since the loads can be locally inspected without the need to install pressure sensors and momentum balances in rotating devices. The applicability of the approach in problems relevant to the aerospace industry requires theoretically defining and experimentally verifying the principles of this method. Modern aircraft propellers operate in the compressible regime, in conditions where the blade profiles are usually experiencing transonic effects, especially at the blade tip. Therefore, the PIV based load determination is firstly applied in airfoils immersed in transonic flows (Mach 0.6 to 0.8) and further compared to conventional pressure measurement techniques to measure the surface pressure distribution, airfoil lift and drag. Three different fields of view have been used at different spatial resolutions, to obtain 2D velocity vector fields from which the surface pressure, as well as the lift and drag coefficients were computed. In the lift computation, the contour integration method is applied, whereas the drag is derived from a wake traverse approach. The surface pressure showed excellent agreement with the data recorded by the pressure orifices in the absence of shocks, although to correctly capture the pressure on the nose region of the airfoil an extrapolation of the PIV data towards the actual surface is needed, in view of the large pressure gradient normal to the surface and to the limited spatial resolution. The lift obtained by PIV can be reliably compared to conventional load determination approaches, showing uncertainties of the order of few percent. On the other side, the drag needs a proper experimental optimization to reach the same uncertainty values of the lift. In the drag coefficient computation, the wake based formulation is crucial to obtain accurate results. Main parameters in the drag determination from PIV data are the effect of the free stream pixel shift on the accuracy of the velocity derivative computation and the influence of the algorithm employed for the pressure reconstruction. An experimental investigation revealed that an increase in the pixel shift (increase in pulse separation) reduces the uncertainties in the outer part of the wake. The drag coefficient computation showed how the use of a nondirectional high order global integration algorithm improves the reliability of the drag computation by a factor of 2.5 in comparison to the one of a planar spatial marching algorithm. When using PIV on scaled down models operating in the transonic regime, the particle inertia cannot be considered negligible. Consequently, the flow tracer motion departs from the one of the surrounding fluid, compromising the accuracy of the measurement technique. The phenomenon is investigated examining several types of particle tracers (liquid droplets and solid particles) with the “shock wave test”. The main results of this study indicate that the temporal response of DEHS droplets of diameter in the one micron range is within 2 microseconds, overcome by properly treated (dehydrated) solid particles of sub micron diameter (SiO2 or TiO2 agglomerates) yielding a relaxation time as short as half of a microsecond. The second application focuses on aircraft propellers, where the PIV based load determination technique is compared to computational fluid dynamics (CFD), due to the technical limitations in instrumenting small blades operating at high rotational speed. The first study deals with the determination of the cross sectional aerodynamic loads on a scaled down aircraft propeller model operating at zero angle of incidence. The stereoscopic PIV technique is employed to perform phase locked measurements of the flow around the blade at 75% blade radius. The aerodynamic force is evaluated considering a control volume, for momentum integration, that moves at the same speed as the blade section. This formulation has the important advantage that the unsteady terms in the momentum equation are eliminated, simplifying the data acquisition and processing. The study of three dimensional effects occurring at the blade tip is conducted by dedicated experiments, whereby the three velocity components are measured at several planes by stereoscopic PIV with a traversing system along the blade radius. The consistent treatment of the three dimensional flow requires the velocity derivatives to be evaluated along the span wise direction. This is achieved by measurements with small separation along the radial direction, similarly to the dual plane stereoscopic PIV technique. Further comparison with a CFD simulation shows that the aerodynamic loads can be estimated in the three dimensional regime with similar accuracy as in the two dimensional one. The results demonstrated that phase locked measurements allow resolving the periodical flow of the blade revolution. A quantitative analysis of the measured pressure fields demonstrated how the propeller blade becomes less tractive as the measurement planes move to the tip, and shows the corresponding decrease in the blade resistance due to the presence of the trailing vortex. The numerical simulation confirmed the experimental pressure analysis, providing comparable results with maximum differences of the order of 10% in the numerical pressure coefficient, which may partially be ascribed to uncertainties in the representation of the real blade shape in the numerical model. The sectional PIV derived thrust proved the most in agreement with the one from simulation data, showing the expected decrease in traction up to the tip in both the CFD and PIV results. The experimental sectional drag, due to the limited resolution in capturing the thin blade wake, compares favorably to the numerical data mainly at the inboard part of the measurement domain, while a consistent deviation between experiment and simulation was observed at the immediate tip region. An unprecedented result of the multi plane analysis is the evaluation of the pressure over the entire surface of the blade, which shows the full potential of this technique for propeller blades load diagnostics. The techniques developed in the Aerodynamics Laboratories of TU Delft are finally employed at a larger scale in the industrial wind tunnels of the German Dutch Wind tunnels consortium (DNW), where the thrust and torque forces derived from PIV on a Hamilton Standard aircraft propeller model are meant to be compared to the forces obtained from a shaft balance and a multi component external one.","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamica","","","",""
"uuid:83aa2a53-dee5-429d-8cbe-e8bbe297de70","http://resolver.tudelft.nl/uuid:83aa2a53-dee5-429d-8cbe-e8bbe297de70","Residual strength analysis of structures in aluminium alloy and fibre metal laminates","Zaal, K.J.J.M.","Arbocz, J. (promotor); Schijve, J. (promotor)","1995","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:bd54ed1a-a450-456c-bb95-d89a64695bbf","http://resolver.tudelft.nl/uuid:bd54ed1a-a450-456c-bb95-d89a64695bbf","Laminar-turbulent transition in boundary layers with adverse pressure gradient","Van Hest, B.F.A.","Van Ingen, J.L. (promotor)","1996","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1e56b3a7-b595-48c9-8110-dfea7b28955f","http://resolver.tudelft.nl/uuid:1e56b3a7-b595-48c9-8110-dfea7b28955f","Present-day kinematics at the Azores-Gibraltar plate boundary as derivated from GPS observations","Da Silva Fernandes, R.M.","Ambrosius, B.A.C. (promotor)","2004","","GPS; tectonic plate models; Azores-Gibraltar plate boundary","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4d535d87-d11e-4916-9143-5e6762c56152","http://resolver.tudelft.nl/uuid:4d535d87-d11e-4916-9143-5e6762c56152","Aerodynamic Mechanisms of Flapping Flight","Percin, M.","Scarano, F. (promotor); van Oudheusden, B.W. (copromotor); de Croon, G.C.H.E. (copromotor)","2015","The growing need for mobile aerial platforms capable of performing reconnaissance tasks and gathering intelligence in hazardous and physically inaccessible areas has given rise to an increasing interest in the development of micro aerial vehicles (MAVs), in view of their potential capabilities of versatile and highly maneuverable flight. Especially flapping-wing configurations, which often tend to be inspired by nature, have captivated researchers in view of their possible advantages over more conventional (fixed and rotary wing) flight modes. Contrary to these more conventional flight configurations, flapping wing systems benefit from the unsteady flow effects that are associated with the large-scale vortical structures separating from the wing leading and trailing edges, which create low pressure regions around the wings that lead to the generation of higher lift and thrust. In this respect, the present thesis pursues an experimental exploration of the aerodynamic mechanisms of flapping-wing phenomena by use of state-of-the-art flow measurement techniques, which are capable of providing time-resolved three-dimensional information. The study is divided into two parts, in which flapping-wing aerodynamics is investigated in the context of a flapping-wing MAV (Part I) and in a generic experimental setup to gain more fundamental understanding (Part II), respectively. The first part consists of studies performed with the flapping-wing MAV DelFly II. First, the aerodynamic performance of the DelFly II is assessed by means of extensive force, power consumption and wing deformation measurements. Force and power consumption measurements were performed under in-air and in-vacuum conditions in order to properly identify the contributions associated to the aerodynamic effects. Subsequently, the balance-mounted force measurements are compared to the forces estimated from free-flight visual tracking measurements in order to characterize the effects of fixed-model force measurements, which restrict the dynamic body modes that exist in actual free-flight conditions as well as introducing the effect of the vibrations which depends on the model clamping position. The comparison of the unsteady forces obtained by the two methods reveals that the X-force component (i.e., the force component along the DelFly fuselage as defined in the body axis) shows a good correspondence, whereas the Z-force component displays deviations depending of the flight condition. Reasons for the differences and main drawbacks of the two force determination techniques are discussed. Effects of the flapping frequency, wing surface thickness and wing geometry on the aerodynamic performance in hovering conditions are also investigated in terms of force and power consumption measurements. In order to assess the relation between the force generation mechanisms and wing deformation characteristics, dedicated structural deformation measurements were performed on the flapping wings of the DelFly. These measurements provide information regarding the effects of the flapping frequency and wing surface thickness on the force generation mechanisms and the power consumption characteristics in terms of both amplitude and temporal evolution. Next, flow field measurements were performed around the wing and in the wake of the DelFly in hovering and forward flight conditions by using planar and stereoscopic particle image velocimetry (stereo-PIV) techniques. The visualizations of the vortical structures around the wings reveal the formation, shedding and interaction mechanisms, particularly visualizing the clap-and-peel motion of the DelFly wings. A momentum-based approach in a control volume around the DelFly in hovering configuration was employed to estimate the flap-averaged X-force under a number of simplifying assumptions. This approach, which only uses the streamwise velocity at a downstream location, is still able to calculate the forces within an error range of 5-15 %. The flow field measurements in the wake of the flapping wings in the forward flight configuration are used to reconstruct three-dimensional wake structures. Two wake reconstruction strategies have been compared: (1) a spatio-temporal wake reconstruction based on the Taylor's hypothesis; (2) a spatial wake reconstruction by means of a modified Kriging regression technique, that takes into account the measurement uncertainties. It is shown that wing–wing interaction at the start of outstroke (peel motion) becomes a dominant feature for reduced frequencies greater than 0.62, while becoming relatively inactive at lower reduced frequency. In the second part, experimental studies concerning the fundamental research in flapping-wing flight are reported. First, the effects of wing flexibility on the unsteady flow around a flexible wing undergoing a clap-and-fling type flapping motion have been investigated by means of tomographic PIV measurements that were performed in a water tank. The two-dimensional Euler-Bernoulli beam equation was used to simulate the chordwise deformations of a plunging thin plate and to compare the deformation characteristics between in-air and in-water conditions. The comparison of in-air and in-water deformation characteristics reveals that it is not possible to achieve identical deformation characteristics, because the inertial forces are significantly reduced under in-water conditions. Second, the evolution of three-dimensional flow fields and unsteady forces are reported for surging and pitching flat plates in revolving motion starting from rest. Tomographic PIV measurements were carried out to acquire the three-dimensional flow fields with force measurements being simultaneously performed. The experiments were carried out for a number of parameters to explore the effects of acceleration period, Reynolds number, angle of attack, number of revolutions and pitch rate. Comparison of the force histories shows that the pitching wing generates considerably higher forces compared to the surging wing. Further analysis was performed to determine the reasons for the enhanced force generation of the revolving-pitching wing. It is shown that the increased force production is associated to a formation of additional circulation (bound and LEV), a higher growth rate of the LEV and more favourable vortex trajectories. It is also revealed that the force generation phenomenon is relatively insensitive to the Reynolds number. Moreover, the forces at the steady-state phase do not depend on the motion kinematics and force histories in the start-up phase.","flapping-wing aerodynamics; flapping-wing micro air vehicles; unsteady aerodynamics; particle image velocimetry","en","doctoral thesis","","","","","","","","2016-12-31","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","","",""
"uuid:45a7a7ac-a658-4274-9899-6f7e34d63334","http://resolver.tudelft.nl/uuid:45a7a7ac-a658-4274-9899-6f7e34d63334","Revealing the skeleton from imperfect point clouds","Bucksch, A.K.","Lindenbergh, R. (promotor); Menenti, M. (promotor)","2011","Quantifying our surrounding environment in terms of sizes and orders has always been of interest, because it enables us to visualize, describe and interpret our environment. In the last decade terrestrial laser scanners became available as a tool to measure objects in our surrounding environment. Terrestrial laser scanning samples surfaces with millions of 3D points to be stored as a point cloud. These point clouds contain information of sizes and orders of the sampled objects. Recently, trees became an object of high interest, because they contain a rich and complex structure, which is to be exploited in terms of branch length, branch diameter and branching hierarchy. Such information can be used for forestry, hydrology, ecology and visualization applications. This thesis introduces the SkelTre algorithm (Skeletonization of Trees) as a method to extract a structure description from point clouds. Such a structure description is a socalled skeleton which is similar to a collection of connected lines. A skeleton enables us to extract the branching hierarchy and the size parameters of tree branches from point clouds. Laser scanned point clouds contain only information about the surface of a scanned object and no information about its inside. One benefit of SkelTre is its ability to extract a skeleton purely from the surface samples represented in the point cloud. The SkelTre algorithm meets four main requirements explicitly: 1. Topological preservance - to enable the branching hierarchy extraction 2. Metric representation - to enable the measurement of sizes 3. Imperfect data handling - to address data characteristics such as noise, underampling and varying point density 4. Computational efficiency - to address the need for fast data processing on the given huge amount of data The SkelTre algorithm treats all four requirements based on one single characteristic, the local elongation direction. This elongation direction describes locally how an object surface is sizing in a 3D space. A local elongation direction can be extracted from the given imperfect data by analyzing small cubical cells subdividing the point cloud into a 3D raster. The cubical cells are derived from a so-called octree subdivision. For each cell it is analyzed which side of the cell is passed by the point cloud. The passed sides are representing the local elongations which are further represented by a graph. In this graph, each cell is corresponding to a vertex. If cells share a passed side, than the corresponding vertices are linked by an edge. The input point cloud is imperfect, because it contains noise, undersampling and varying point densities. Therefore, SkelTre treats these point cloud characteristics explicitly, to produce a result that is correctly representing the branching hierarchy. Therefore, before the graph is reduced to the skeleton a robustness criterion is applied. This criterion removes and adds edges to the graph. Edges are added on locations where data is missing because of undersampling or removed when noise causes unintended edges. At this stage the graph ideally represents the surface of an object and is to be reduced to a skeleton. This corrected graph is then reduced to a skeleton by a set of newly developed rules. The reduction uses two suited vertex configurations occurring in the graph, so-called E-Pairs and V-Pairs. Basically the reduction relies on the property, that whenever an E-Pair is found and reduced, one or more V-Pairs are generated. Processing of a V-Pair leads to either new V-Pairs or otherwise a new E-Pair has to be found in the graph. If neither an E-Pair or a V-Pair is present in the graph it is ensured that the result is a skeleton. The resulting skeleton is related to a known topological structure, the Reeb-Graph. During the reduction of the graph, the graph is embedded into the point cloud such that every vertex is locally centered within the point cloud. The correct branching order and centeredness enables the navigation to a chosen location in the point cloud to derive a branch diameter. A first implementation of the algorithm is given to demonstrate its efficiency on huge point cloud data. On many examples it is evaluated, that all four requirements are met. These examples include non-tree objects to emphasize the generality of the introduced skeletonization framework. The practical use of the SkelTre algorithm is demonstrated on two applications demanding automatic size measurements on trees. In contrast to older methods, both applications do not rely on pre-knowledge of the tree species. Hence, the assessment of trees in these applications is purely based on the point cloud data. Both applications use the newly developed HARPER method to estimate the diameter under support of the SkelTre skeleton. The HARPER method estimates the diameter of a branch on the basis of the double distance of the point cloud points to the skeleton. The length of branches is derived as the sum of the edge lengths in the skeleton of a branch. The first application is the automatic estimation of the tree parameters branch length and branch diameter from laser scanned orchard trees. The estimated parameters are a key to understand a number of physiological processes in the tree canopy. Furthermore, these parameters are useful to determine the vitality of a tree. Orchard trees are optimized by branch cuttings to maximize the crop load on the tree. These cuttings destroy the growth pattern of the tree. Therefore, assumptions about the growth pattern can not be made for the estimation of the branch sizes. For these orchard trees the branch length and diameter was derived with the HARPER method. High correlations above 0.9 between field and automatic measurement were found in the frequency distributions of the branch length and diameter classes. These results show that automatic measurement of tree parameters from terrestrial laser scans is possible. The second application demonstrates a possible future use of the SkelTre skeleton. Here, the skeletonization was applied to airborne obtained laser point clouds to estimate the trunk diameter at breast height (1,30m). The diameter at breast height is one key parameter for calculating hydrological roughness in flooding areas and to estimate the woody volume of a tree. The density of airborne obtained point clouds is only 75 points per square meter. Still, the trunk diameter at breast height could be extracted. On simulated airborne scanned trees a correlation of 0.97 was achieved between the diameter at breast height of the known simulated trees and the HARPER method. Furthermore, test cases were extracted from the airborne obtained point cloud of the recently updated Actual Height Model of the Netherlands, AHN2. On these test cases the estimated diameter with the HARPER method deviated less than a standard cylinder fitting method from manually measured diameters in the field. Still, the validation of a whole forest remains difficult, because not all trees of the forest are found back in the AHN2 point cloud. Such AHN2 point clouds will be available for the whole Netherlands in 2013 and other countries collect similar point clouds at this time. The wide availability of such point clouds in future underlines the relevance of this application.","skeleton; SkelTre; point cloud; terrestrial laser scanning","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:bd728e02-f403-4cea-9e2b-65b04b47b3f7","http://resolver.tudelft.nl/uuid:bd728e02-f403-4cea-9e2b-65b04b47b3f7","Interplanetary laser ranging: Analysis for implementation in planetary science missions","Dirkx, D.","Vermeersen, L.L.A. (promotor); Visser, P.N.A.M. (promotor)","2015","Measurements of the motion of natural (and artificial) bodies in the solar system provide key input on their interior structre and properties. Currently, the most accurate measurements of solar system dynamics are performed using radiometric tracking systems on planetary missions, providing range measurement with an accuracy in the order of 1 m. Laser ranging to Earth-orbiting satellites equipped with laser retroreflectors provides range data with (sub-)cm accuracy. Extending this technology to planetary missions, however, requires the use of an active space segment equipped with a laser detector and transmitter (for a two-way system). The feasibility of such measurements have been demonstrated at planetary distances, and used operationally (with a one-way system) for the Lunar Reconaissance Orbiter (LRO) mission. The topic of this dissertation is the analysis of the application of interplanetary laser ranging (ILR) to improve the science return from next-generation space missions, with a focus on planetary science objectives. We have simulated laser ranging data for a variety of mission and system architectures, analyzing the influence of both model and measurement uncertainties. Our simulations show that the single-shot measurement precision is relatively inconsequential compared to the systematic range errors, providing a strong rationale for the consistent use of single-photon signal-intensity operation. We find that great advances in planetary geodesy (tidal, rotational characteristics, etc.) could be achieved by ILR. However, the laser data should be accompanied by commensurate improvements in other measurements and data analysis models to maximize the system's science return. The science return from laser ranging data will be especially strong for planetary landers, with a radio system remaining the preferred choice for many orbiter missions. Furthermore, we conclude that the science case for a one-way laser ranging is relatively weak compared to next-generation radiometric tracking systems, requiring the development of much more accurate space-based clocks.","interplanetary laser ranging; planetary geodesy; planetary missions; space-based clocks; experimental gravitation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:dba65f4b-a4e1-407a-8cbd-4931a2df4cf3","http://resolver.tudelft.nl/uuid:dba65f4b-a4e1-407a-8cbd-4931a2df4cf3","Fatigue and Damage Tolerance of Friction Stir Welded Joints for Aerospace Applications","Lemmen, H.J.K.","Benedictus, R. (promotor)","2010","Friction stir welding is a young welding process with high potential to replace riveted joints in aerospace structures like the fuselage. Friction stir welding is a robust process and capable of welding high strength aluminum alloys. Therefore it can lead to both costs and weight savings. To substitute riveted joints by friction stir welded joints, it must be shown that the damage tolerance of the welded structure is similar as the structure with riveted joints. As the aerospace industry has over 50 years of experience with riveted joints, this is quit a challenge. The damage tolerance behavior of riveted joints is fully understood and the predictability is high. To get friction stir welded structures at the same level of readiness, the fatigue behavior of friction stir welded joints must be fully understood. The main focus of this research was to investigate the fatigue behavior, i.e. fatigue initiation and fatigue crack growth, of friction stir welded aerospace aluminum in order to understand which parameters play a role. This knowledge enables to build prediction models which can be used to evaluate the damage tolerance of a welded structure. Consequently, it is possible to come up with design rules for a damage tolerant friction stir welded fuselage structure.","friction stir welding; damage tolerance; fatigue initiation; fatigue crack growth; residual stress; yield strenght profile","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Structural Integrity","","","",""
"uuid:d4dae2c0-28c2-4a92-95cf-cae4136d2820","http://resolver.tudelft.nl/uuid:d4dae2c0-28c2-4a92-95cf-cae4136d2820","Development and validation of a computer assisted design methodology for gas-turbine-based aircraft engines","Eftekhari Shahroudi, K.","Torenbeek, E. (promotor); Van Buijtenen, J.P. (promotor)","1994","","CAD; aircraft engines","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:538b0174-fe84-43af-954d-02f256b2ec50","http://resolver.tudelft.nl/uuid:538b0174-fe84-43af-954d-02f256b2ec50","Fault Tolerant Flight Control: A Physical Model Approach","Lombaerts, T.J.J.","Mulder, J.A. (promotor); Chu, Q.P. (promotor)","2010","Safety is of paramount importance in all transportation systems, but especially in civil aviation. Therefore, in civil aviation, a lot of developments focus on the improvement of safety levels and reducing the risks that critical failures occur. When one analyses recent aircraft accident statistics, it is clear that a significant portion is attributed to “loss of control in flight”. A recent worldwide civil aviation accident survey for the 1989 to 2003 period, conducted by the Civil Aviation Authority of the Netherlands (CAA-NL) and based on data from the National Aerospace Laboratory NLR, indicates that this category accounts for as much as 17% of all aircraft accident cases. This has led to a common conclusion: from a flight dynamics point of view, with the technology and computing power available on this moment, it might have been possible to recover a part of the aircraft in the accident category described above on the condition that non-conventional control strategies would have been applied. These non-conventional control strategies involve the so-called concept of fault tolerant flight control (FTFC), where the control system is capable to detect and adapt for changes in the aircraft behaviour. One FTFC strategy option is using a model based control routine. This research focuses on a physical modular approach. In this setup, not only a reconfiguring controller is needed, but also a suitable FDI/identification strategy. This research focuses on both components. In this reseach project, a real-time aerodynamic model identification procedure has been combined with a model based adaptive control method. A manual as well as an autopilot version have been developed. The autopilot version has been evaluated on desktop simulations, the manual version has been tested in the Simona Research Simulator involving professional airline pilots. Both tests have demonstrated promising results. The autopilot performance is very good, and the manual controller has demonstrated to increase handling qualities and to reduce pilot workload of the damaged aircraft. These are very promising results that motivate further research in this field.","Flight Control; Adaptive Control; Model-based Control; Damage; Failure; Detection; Identification; Nonlinear; Real-time; Simulator","en","doctoral thesis","T.J.J. Lombaerts","","","","","","","2010-05-25","Aerospace Engineering","Control and Simulation","","","",""
"uuid:91f8b69b-2ded-4dd7-bf8e-e9e355efbd6f","http://resolver.tudelft.nl/uuid:91f8b69b-2ded-4dd7-bf8e-e9e355efbd6f","Differential-geometric considerations on the hodograph transformation for irrotational conical flow","Reyn, J.W.","Timman, R. (promotor)","1961","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c1715834-0af2-434d-b9c6-aecf527ed846","http://resolver.tudelft.nl/uuid:c1715834-0af2-434d-b9c6-aecf527ed846","Frequency analysis of fluids and fluid-structure systems","Schulkes, R.M.S.M.","Veldman, A.E.P. (promotor)","1990","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a1127a0e-f813-4049-9667-aa9badd3d203","http://resolver.tudelft.nl/uuid:a1127a0e-f813-4049-9667-aa9badd3d203","Integrated silicon flow sensors","van Oudheusden, B.W.","Middelhoek, S. (promotor); van Ingen, J.L. (promotor); Huijsing, J.H. (promotor)","1989","","fluid flow measurements; gas flow measurement","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a099944c-3ee5-4476-aa2f-114a87fb1f62","http://resolver.tudelft.nl/uuid:a099944c-3ee5-4476-aa2f-114a87fb1f62","Pilot Control Behavior Discrepancies Between Real and Simulated Flight Caused by Limited Motion Stimuli","Zaal, P.M.T.","Mulder, M. (promotor); Mulder, J.A. (promotor)","2011","Flight simulators provide a flexible, efficient, and safe environment for research and training at much lower costs than real flight. The ultimate validity of any simulation would be achieved when – for a particular task – human cognitive and psychomotor behavior in the simulator corresponds precisely to the behavior in the aircraft being simulated. However, it has been shown that for skill-based aircraft control tasks, pilot performance and control behavior are significantly affected by simulator motion cueing settings. Current technology centered fidelity metrics do not reflect to what extent a simulator is able to induce real flight pilot behavior, as they do not incorporate knowledge about human perception and control processes. This warrants the development of a new fidelity metric that determines the simulator’s ability to induce real-flight pilot control behavior. At the Faculty of Aerospace Engineering of Delft University of Technology a research project is dedicated to develop such a behavioral fidelity metric using a cybernetic approach. A prerequisite for developing this fidelity metric is to know exactly how pilot control behavior is affected by the limited physical motion stimuli that are typically provided in a simulator. Furthermore, the knowledge on pilot control behavior in a real aircraft – the baseline – needs to be greatly expanded. The project consists of five steps. In the first step of the project, new identification techniques and methodologies are developed to accurately identify multimodal control behavior. In the second step, pilot control behavior is determined in real flight. The third step constitutes the identification of control behavior in the simulator under an array of different motion cueing conditions. This allows for a systematic comparison of control behavior between real and simulated flight. In the fourth step of the project, this knowledge is used to trace behavioral discrepancies back to the way motion stimuli are presented in the simulator, and improve motion cueing algorithms to increase simulator behavioral fidelity. In the fifth and final step, standards and metrics for behavioral fidelity are developed. This thesis work covers the first three steps of the project. The final goal of this thesis is then to determine how pilot control behavior is affected by the limited motion cues provided in a simulator by comparing control behavior in the simulator under different motion cueing conditions to control behavior in the aircraft. The research will be limited to the effect of different motion cueing settings in a pitch control task. Steps four and five of the project will be covered in another thesis by ir. D.M. Pool. Using a cybernetic approach, pilot control behavior can be characterized by estimating the parameters of quasi-linear pilot models. In previous studies, this approach was used to compare pilot control behavior between real and simulated flight. However, in all these studies only a single, lumped, pilot response function was identified, without distinguishing between the contributions of different perceptual modalities, for example, visual and vestibular. In a multi-sensory environment, such as a motion-base flight simulator, this may obscure the pilot’s ability to adopt a different control strategy by a different use of perceptual modalities. Therefore, to compare control behavior between real and simulated flight adequately, multimodal pilot models need to be identified that are able to model the pilot’s use of modalities separately. The identification of these models requires a combined target-following disturbance-rejection task, as multiple forcing functions need to be inserted at different locations in the control loop, to allow for accurate estimation of the model parameters. At the start of this project, multimodal pilot control behavior had never been identified in real flight. The requirement for a combined target-following disturbance-rejection task complicates the setup of the in-flight experiments significantly. In the aircraft, the introduction of a single target tracking signal is relatively straightforward, as it can be visualized on a display in the cockpit. In-flight disturbance-rejection tasks are much more difficult to perform however, as introducing a deterministic disturbance on the stick-free aircraft motion requires an additional input other than the pilot’s control actions to be sent through the flight control system of the aircraft. To facilitate the experiments for the identification of in-flight multimodal pilot control behavior as part of this thesis work, a novel fly-by-wire system was developed for the Cessna Citation II laboratory aircraft of the Delft University of Technology. This fly-by-wire system allows for the disturbance of the aircraft motion by adding a disturbance signal to the pilot control signal. The system is novel in its design due to the use of the existing electric automatic control system in the aircraft, limiting the modifications to the aircraft. As the variations in pilot model parameters between different experiment conditions are often subtle and the aircraft measurements are relatively noisy, the model parameters should be estimated with the highest accuracy. Traditional two-step parameter estimation methods – used in many previous experiments – often produce less accurate results, as the inaccuracies from the frequency response identification step propagate to the parameter estimation step. To increase the accuracy of the multimodal pilot model parameter estimates, a new parameter estimation technique for multimodal pilot models was developed and addressed in this thesis in Chapter 2. The technique is based on the well-known concept of maximum likelihood estimation. Due to the relatively high levels of remnant noise in experiment data and the presence of redundant parameters in the pilot model, the maximum likelihood parameter optimization problem is very complex with many local minima. To increase the likelihood that the global optimum solution of the parameter vector is found, a genetic algorithm is combined with a more common gradient-based Gauss-Newton algorithm. The advantage of the new identification technique is that it operates solely in the time domain, increasing the accuracy of the parameter estimates compared to the two-step methods traditionally used in this type of research. Using the new identification technique, the parameters of a multimodal pilot model are estimated most accurately when as many forcing functions are inserted into the closed-loop control task at different locations, as the number of modalities to be identified. However, the power requirements of the different forcing functions were not known. In addition, little was known about how pilot control behavior is affected by using multiple forcing functions in a control task as opposed to a single forcing function. The first experiment in this thesis, discussed in Chapter 3, was therefore performed to investigate these two unknowns. The results of the experiment showed that multimodal pilot control behavior is significantly affected by the relative power settings of the target and disturbance forcing functions. When the power of the target forcing function is increased – simultaneously reducing the power of the disturbance forcing function – the cue conflict between the visual and physical motion cues increases, as the target forcing function – as opposed to the disturbance forcing function – is only presented visually. This causes pilots to control with a lower visual gain, while the visual perception time delay becomes higher. In addition, pilots reduce their visual lead and increase their vestibular gain when the power of both forcing functions becomes similar. The result of this change in control strategy is a reduction in tracking performance and control activity. It was found that multimodal pilot control behavior can be evaluated by using a combined target-following disturbance-rejection task with an additional signal with relatively small magnitude. In contrast to frequency-domain identification methods, the maximum likelihood based parameter estimation method has no strict requirement for the use of multi-sine signals as forcing functions in a closed-loop control task. This allows for an exploration into new types of signals to be used in manual control experiments. New types of target signals allow for manual control tasks that are more comparable to real piloting tasks. For example, roll ramp or step target signals introduce a task that is similar to flying a turn maneuver. The second experiment in this thesis (Chapter 4) was developed to investigate the identifiability of multimodal pilot control behavior using ramp and step target signals. In addition, the effect of these signals on pilot performance and control behavior itself was investigated. The experiment revealed that, in terms of performance, a task with ramp target inputs is comparable to a task without a target input. The step target inputs introduce a large increase in error variance, due to the transient behavior at the location of the steps. The step target inputs also result in significantly different response functions of the modalities of the pilot compared to the multi-sine and ramp target inputs, which induce comparable response functions. Based on the findings of the experiment, ramp signals as target forcing function are the best alternative to multi-sine target signals in keeping the ability to separate the pilot response functions for different modalities, while creating a task that is more equivalent to an actual piloting task. The results of the first two experiments were used to optimize the experiments in the remainder of the thesis. Before the actual in-flight and simulator comparison experiments were performed, several preliminary studies were undertaken to get insight into how pilot control behavior is affected by the different motion components that make up the total aircraft motion. In a pitch control task, the total aircraft motion at the pilot station can be decomposed into pitch rotational motion, pitch heave motion, and center of gravity heave motion. Pitch heave is the linear acceleration induced by the pitch rotation of the aircraft and the relative position of the pilot station in front of the center of gravity. Center of gravity heave results from relatively slow changes in aerodynamic lift due to the change in aircraft angle of attack while pitching. In conventional hexapod simulators, the center of gravity heave component is the most problematic to simulate accurately, as its low-frequency high-amplitude characteristics drive the simulator motion system to its limits. Therefore, in most simulator applications, the linear accelerations are heavily attenuated by a motion filter. By increasing the knowledge on how the different motion components are used by the pilot to form a control action, the individual components could be filtered more efficiently to increase behavioral fidelity in future simulator applications. The third experiment, discussed in Chapter 5 of this thesis, was set up to increase this knowledge on how pitch rotational motion, pitch heave motion, and center of gravity heave motion are used by a pilot performing a pitch control task. The results of the experiment indicated that – in a pitch target-following disturbance-rejection task – pitch motion significantly improved tracking performance, with an increased cross-over frequency for the disturbance open-loop. The increase in performance is a result of an increased visual gain and a reduction in visual lead, resulting in a lower effective time delay for the disturbance open-loop. For the Cessna Citation dynamics used, pitch heave motion showed effects similar to pitch rotational motion, but less strongly in part due to the relative short distance of the pilot station to the center of gravity and the motion filter that was used in the experiment. The presence of the center of gravity heave motion cue was found to have no significant effect on performance, however, visual lead significantly increased. This indicates that pilots reduce the use of motion cues in exchange for visual cues in the presence of center of gravity heave motion. A follow-up study focused on the effects of the filtering of pitch heave motion on pilot control behavior. The fourth experiment described in this thesis (Chapter 7) was the first experiment to identify multimodal pilot control behavior – separating the pilot’s visual and vestibular responses – in real flight. The experiment was performed with the new fly-by-wire system in the Cessna Citation II laboratory aircraft and was designed to gain more insight into the control system limitations and the optimal use of the system in future in-flight experiments on the identification of multimodal pilot control behavior. The required deterministic disturbance of the aircraft motion was facilitated by adding a disturbance forcing function to the fly-by-wire control signal. Accurate pilot model parameter estimation results could be obtained using multi-sine and ramp target signals in a pitch and roll task, despite some limiting of the fly-by-wire control signals. The limiting of control signals introduces nonlinearities in the closed control loop. However, the achieved accuracy and the multimodal pilot model parameter values were comparable to estimates from previous flight simulator experiments. These results allowed for the optimization of the final experiment discussed in his thesis in which multimodal pilot control behavior between real and simulated flight was compared. In the final experiment, discussed in Chapter 8, pilots performed a pitch target-following disturbance-rejection task in a simulator under different motion cueing settings, in addition to performing the task in an aircraft in flight, the baseline condition. Except for the applied variation in motion fidelity, differences in experimental setup between the aircraft and the simulator were kept as small as possible. Pilot performance and control behavior were slightly affected by differences in the display and sidestick setup. However, the effects introduced by motion fidelity were far more apparent. For the pitch target-following disturbance-rejection task performed, pilot performance and multimodal pilot control behavior were significantly affected by simulator motion fidelity. For improved motion fidelity towards the full-motion condition in the aircraft, pilot disturbance rejection improved. For higher levels of motion fidelity, the visual lead and lag time constants decreased, while visual and vestibular time delays increased. The lead and lag time constants approximate the characteristic time constants of the controlled aircraft dynamics much better when physical motion is present in the simulator and in flight, revealing the importance of simulator motion for these skill-based tracking tasks. From the limited number of motion conditions tested in this thesis, multimodal pilot control behavior in the simulator motion condition with full pitch motion and filtered pitch and c.g. heave motion best approximates in-flight pilot control behavior. The cybernetic approach proved to be a valuable concept in assessing simulator motion fidelity. Distinct variations in multimodal pilot model parameters were found between conditions with different motion fidelity showing the pilots’ adaption to the supplied motion cues, while the pilots rated these conditions the same on a motion fidelity rating scale. As a recommendation for future work, to investigate the effect of reduced motion fidelity more accurately, experiments should be performed on a single apparatus capable of large motion displacement that allows for simulation of full aircraft motion. This would eliminate the effects of differences in experimental setup experienced in this thesis work. Future research should also be more geared towards simulator fidelity as a whole, as the reduced fidelity of simulator systems other then the motion system (for example, out of the window visual systems) have also shown to influence pilot control behavior. Finally, more research should be devoted to identification techniques that are capable of separating more perceptual modalities and techniques for modeling pilot control behavior in tasks that are more comparable to real piloting tasks.","Flight Simulation; Control Behavior; System Identification; Motion Cueing","en","doctoral thesis","P.M.T. Zaal","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:bb6080e3-0b4f-4a00-87ec-afb4796adb5c","http://resolver.tudelft.nl/uuid:bb6080e3-0b4f-4a00-87ec-afb4796adb5c","Perception Coherence Zones in Vehicle Simulation","Valente Pais, A.R.","Mulder, M. (promotor)","2013","A perception coherence zone (PCZ) designates the range of inertial motion levels that, although not being a one-to-one match with the visual motion levels, are still considered by the subjects as being part of a coherent movement. Two types of PCZs were studied: amplitude PCZs and phase PCZs. Amplitude and phase coherences zones were measured for different types of stimulus frequency and amplitudes, for different degrees-of-freedom and using different motion simulators. The resulting data were compiled and it was demonstrated how perception coherence zones can be used to assess motion cueing solutions, and to derive motion cueing criteria. The coherence zones criteria were shown in a modified Sinacori plot. In a Sinacori plot, motion criteria are represented in terms of acceptable motion gain and phase distortion at the frequency of 1 rad/s. Since coherence zones were measured at different frequencies and amplitudes, it was possible to expand that representation to different frequencies and amplitudes. The coherence zone assessment method and criteria provide three important additions to the already available criteria. First, it presents not only criteria for desirable motion stimuli, but also offers a systematic, objective, human-perception-based method to measure the limits of the criteria. Second, the coherence zones method and criteria add a third and fourth dimension to the Sinacori plot: frequency and amplitude. By doing so, the coherence zone criteria do not depend on a specific motion filter structure. Third, by offering a measurement method and allowing different frequencies and amplitudes to be chosen, the coherence zones method can provide simulator-based, task-specific criteria. However, coherence zones as a metric, that is, as a measure of the perceived coherence of the inertial feedback provided, is platform and task independent.","flight simulation; automotive simulation; simulation; human self-motion perception; perception; vehicle simulation; motion cueing; motion filters; motion perception; motion cueing assessment method; motion cueing criteria","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:5e9c5527-220f-4658-b516-459528e62733","http://resolver.tudelft.nl/uuid:5e9c5527-220f-4658-b516-459528e62733","Application of Satellite Altimetry for Global Ocean Tide Modeling","Smith, A.J.E.","Wakker, K.F. (promotor)","1999","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:deec2bf1-e25d-458b-b3c9-35c2810b22a5","http://resolver.tudelft.nl/uuid:deec2bf1-e25d-458b-b3c9-35c2810b22a5","Analysis of the Laser Doppler Measurement Technique for Application in Turbulent Flows","Absil, L.H.J.","van Ingen, J.L. (promotor)","1995","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f4d5801c-042b-44e6-a771-44ef9c330e6f","http://resolver.tudelft.nl/uuid:f4d5801c-042b-44e6-a771-44ef9c330e6f","Physical and numerical aspects of aeroelastic simulations","Prananta, B.B.","Zwaan, R.J. (promotor); Hoeijmakers, H.W.M. (promotor)","1999","","aeroelasticity; time domain; transonic flow; viscous flow; Euler/Navier-Stokes equations; computational aeroelastic simulation; computational fluid dynamics; unsteady; deforming mesh; buffet; buffeting","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5bf6aec3-4662-4211-b1d2-145ca934ca41","http://resolver.tudelft.nl/uuid:5bf6aec3-4662-4211-b1d2-145ca934ca41","Development of a Methodology to Support Design of Complex Aircraft Wings","Cooper, C.A.","Benedictus, R. (promotor); Van Tooren, M.J.L. (promotor)","2011","The design of complex systems in today’s aerospace domain requires a balance between the ever-increasing complexity of the supporting technology and the drive to develop those systems in a compressed timeframe. The performance knowledge of a preliminary design must shift backwards in the lifecycle in order to exploit that knowledge when there is still freedom in the design. Design of aerospace structures with fiber metal laminates (FML) represents one such area where the increased design freedom comes at a cost of increased design complexity. The potential benefits of FML technology, however, demand a solution to this design challenge. FMLs require a different approach to design and manufacturing that so far has been only moderately explored for possible automation. In order to support design of an FML wing, a tailored design methodology and prototyping tools are needed. The quantitative systems engineering field of knowledge based engineering (KBE) provides a solution. A KBE approach, leveraging parametric, geometry-based modeling and expert FML manufacturability knowledge, can work within a design framework to automate many of the non-creative activities of the FML designer, such as initial layup design and manufacturability rule application. This research seeks to frame the FML wing design process, develop critical KBE design modules tailored for FML knowledge, and illustrate their utility in the balance of aerospace structure weight and cost.","fiber metal laminates; knowledge based engineering; systems engineering","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Materials and Manufacturing (AMM); Aerospace Structures & Design Methodologies (AS&DM)","","","",""
"uuid:9d437e58-82c0-4af1-935f-69ba5573c7a2","http://resolver.tudelft.nl/uuid:9d437e58-82c0-4af1-935f-69ba5573c7a2","Tethers in Space: A propellantless propulsion in-orbit demonstration","Kruijff, M.","Ockels, W.J. (promotor); Gill, E.K.A. (promotor)","2011","Space tethers are cables that connect satellites or other endmasses in orbit. The emptiness of space and the near-weightlessness there make it possible to deploy very long and thin tethers. By exploiting basic principles of physics, tethers can provide propellantless propulsion and enable unique applications such as the provision of comfortable artificial gravity or the removal of space debris. Nevertheless there are still no tether applications in use today - there appears to be a ""gap of scepticism"". A safe tether and deployer system has therefore been designed and verified with the help of simulation and innovative ground testing equipment. Through a hands-on educational approach, the YES and YES2 low-cost space tether experiments have been launched into orbit. In September 2007, all 32 km of the YES2 tether are deployed in orbit. With the help of this tether, a student-built re-entry capsule is deorbited over Kazakhstan. This work reports this design and analysis effort, with the aim to raise confidence in the use of space tethers.","tether; space tether; deployment; YES; YES2; debris mitigation; artificial gravity; spacemail","en","doctoral thesis","","","","","","","","","Aerospace Engineering","ASSET/SSE","","","",""
"uuid:f99c58e8-a618-46e7-a3e0-76d286109c5a","http://resolver.tudelft.nl/uuid:f99c58e8-a618-46e7-a3e0-76d286109c5a","Design Considerations for the Glenohumeral Prosthesis","Oosterom, R.","Beukers, A. (promotor); Rozing, P.M. (promotor)","2005","The shoulder joint provides us with a large range of motion. This is enabled by the shallowness of the glenoid cavity and the cooperation of many bone elements of the shoulder girdle. This results in complex biomechanics and dependency to surrounding soft tissues for its stability. Due to a fracture or joint diseases, a shoulder replacement may have to be performed, aiming at removing the excessive pain and to restore joint functionality. Especially post-operative joint functionality is not sufficient to perform tasks of daily living and many post-operative complications occur. Results must be improved, which, among others, can be achieved by design improvements. To restore the natural anatomy, the anatomical glenohumeral prosthesis is used, of which the geometry, insertion and fixation have been investigated. Parallel, a conceptually new design is developed, proposed for patients for whom no long lasting reliable solution is available. This design focuses on integration of lost anatomical functions with improved fixation techniques","shoulder prosthesis; design; stability","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5d83f529-e074-4a30-b00b-b11a3d23dabd","http://resolver.tudelft.nl/uuid:5d83f529-e074-4a30-b00b-b11a3d23dabd","Relative Navigation for Satellite Formation Flying based on Radio Frequency Metrology","Sun, R.","Gill, E. (promotor)","2014","To increase mission return, utilizing two or more spacecraft instead of one may sometimes be superior. This is especially true when a large spaceborne instrument needs to be created through larger and configurable baselines, such as telescopes and interferometers. However, coordinating the alignment of the individual components of such a spaceborne instrument on separate spacecraft (involving the estimation and control of baselines) will require a high level of accuracy for relative navigation and control. The increasing demand of such science missions or challenges on complex functions such as rendezvous and docking calls for high accuracy levels of ranging at centimeter or even millimeter levels. The objective of this research is to investigate key technologies of developing a relative navigation system based on radio-frequency (RF) metrology. This RF-based system inherits Global Navigation Satellite System (GNSS) technologies through transmission and reception of locally generated GNSS-like pseudo random noise (PRN) ranging codes and carrier phases via inter-satellite links. This enables operation, e.g., in high Earth orbits where GNSS constellations are poorly visible. The RF-based navigation system is designed to comprise one transmitter, one receiver and several antennas in order to enable coarse-mode inter-satellite distance estimation (meter level) based on pseudorange measurements and fine-mode distance (centimeter level) and line-of-sight (LOS) estimation (sub-degree level) based on carrier phases in addition to pseudorange. A benchmarking system, called the Formation Flying Radio Frequency (FFRF) sensor, has been successfully shown and demonstrated on PRISMA mission. This research improves the performance of FFRF with respect to the technologies 1) to deal with errors and uncertainties, especially multipath; 2) to perform an unaided, fast and reliable carrier phase integer ambiguity resolution (IAR); and 3) to share channels among multiple spacecraft. Multipath In space applications, receivers on space vehicles may suffer from very short- delay multipath (< 4 m), reflected from the vehicle itself or from other vehicles during the operations of rendezvous and docking. The thesis proposes a novel method, termed ""Multipath Envelope Curve Fitting"", to mitigate very-short-delay-multipath on pseudorange measurements by approximately 50%. It also exhibits a promising performance for medium or large delayed multipath as compared to state-of-the-art methods. The method is based on the fact that the signal strength information, reported by early or late correlators inside the receiver, has an in-phase correlation with the pseudorange multipath error. By linearly combining multiple signal strength estimators from multiple correlators, the pseudorange multipath error has been accurately estimated. The weights for the linear combination were obtained by curve fitting based on the least-squares adjustment. A simple implementation strategy was also proposed that enables a receiver-internal multipath estimation process operated in conjunction with the tracking loop with a minimal additional computational overhead. Compared to the pseudorange multipath, the carrier phase multipath has more significant impacts on high precision navigation, especially when it is coupled with the carrier phase IAR. By making use of the signal to noise ratio (SNR) data of multiple antennas, this thesis proposes a novel cascaded extended Kalman Filter (EKF) to mitigate carrier phase multipath. This method accelerates the IAR process significantly and guarantees an achievement of sub-degree LOS accuracy. Both real-valued and complex-valued EKF are proposed and evaluated. The complex-valued EKF has been found to be insensitive to poorly defined initial conditions, when the real-valued EKF has difficulties converging. Moreover, the complex-valued EKF has shown better convergence properties for SNR observations with a large amount of noise. Integer Ambiguity Resolution The second challenge of this research is to perform an unaided, fast and reliable carrier phase IAR. Single-epoch IAR algorithms are proposed in this thesis, by making use of a nonlinear quadratic LOS length constraint and taking advantages of antenna arrays. Two methods, namely, the validation method and the subset ambiguity bounding method, are proposed. They replace the equality quadratic constraint by inequality boundaries such that the well known Least-squares AMBiguity Decorrelation Adjustment (LAMBDA) integer ambiguity resolution process is implemented within a pre-defined threshold to increase the integer search fidelity. Numerical simulations and field tests demonstrated that both the validation method and the subset ambiguity bounding method provided remarkable improvements with up to 80% higher success rates than the original LAMBDA method based on single-epoch measurements. The validation method showed a slightly better performance than the subset ambiguity bounding method as they differ in utilizing all-ambiguity-set and subset-ambiguity, respectively. Better IAR robustness against multipath can also be observed as compared to the original LAMBDA method. An Ambiguity Dilution of Precision (ADOP) measure under the LOS constraint is derived, which is an easy-to-use and insightful indicator of the ambiguity resolution capability. A rule-of-thumb for the pre-defined threshold has also been derived in the closed-form expression, providing guidance on how to choose boundaries according to the noise level and antenna geometry. Multiple Access Technology Enabling multiple access capability is of critical importance for future missions with four or more spacecraft. The Code Division Multiple Access (CDMA) technology is recommended to be used in combination with a flexible role rotating topology in this research. This allows coping with time-critical relative navigation requirements and enables flexible operations during various mission phases. Through realistic formation case studies, the limitation of CDMA was extensively investigated in terms of the multiple access interference (MAI) which could result in a ranging error of several meters and is highly dependent on the Doppler offset. Recommendations are given in this thesis to reduce corresponding MAI errors.","relative navigation; GNSS; formation flying; multipath; integer ambiguity resolution","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Space System Engineering","","","",""
"uuid:01421204-c938-48fa-baba-61f7065cd65d","http://resolver.tudelft.nl/uuid:01421204-c938-48fa-baba-61f7065cd65d","Efficient and robust uncertainty quantification for computational fluid dynamics and fluid-structure interaction","Witteveen, J.A.S.","Bijl, H. (promotor)","2009","Physical uncertainties due to atmospheric variations and production tolerances can nowadays have a larger effect on the accuracy of computational predictions than numerical errors. It is essential to quantify the effect of these uncertainties for reducing design safety factors and robust design optimization. This eventually contributes to the development of aerodynamically more efficient and environmentally friendly transportation and renewable energy technologies.In this thesis, efficient and robust uncertainty quantification methods are developed for computationally intensive flow and fluid-structure interaction simulations including discontinuities and unsteadiness. The proposed methods satisfy the total variation diminishing and extrema diminishing concepts extended to probability space and result in practice in a constant error in time. The considered applications demonstrate that the developed methods have the potential to advance uncertainty quantification for computationally intensive unsteady problems with discontinuities from practically impossible to a routine analysis. The examples also illustrate that taking physical uncertainties into account is a more reliable design practice than using safety margins in combination with deterministic simulation results.","non-deterministic; extrema diminishing; polynomial chaos; time-dependent","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c5448f7b-8c85-4994-96f8-0a6bb51704e9","http://resolver.tudelft.nl/uuid:c5448f7b-8c85-4994-96f8-0a6bb51704e9","Phase field modelling of the austenite to ferrite transformation in steels","Mecozzi, M.G.","Van der Zwaag, S. (promotor)","2007","Abstract not available","low-carbon steel; ferrite growth kinetics; phase field model; 2D and 3D microstructure simulations","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a7884a2a-4155-45ae-bb87-cf4d9ef5b6c0","http://resolver.tudelft.nl/uuid:a7884a2a-4155-45ae-bb87-cf4d9ef5b6c0","Adaptive image interrogation for PIV: Application to compressible flows and interfaces","Theunissen, R.","Scarano, F. (promotor)","2010","As an experimental tool, Particle Image Velocimetry has quickly superseded traditional point-wise measurements. The inherent image processing has become standardized though the performances are strongly dependent on user experience. Moreover, the arduously selected image interrogation parameters are applied uniformly throughout the image snapshots and image sequence but seldom comply with the observed fluid’s convective motion, spatial distribution in length scales or signal distribution. Instead, a degree of adaptation in the image analyses is required to estimate the velocity field underlying the image recordings as accurate as possible and preferably within an automated fashion. In this work, the aim has been a global solution which through adaptivity of the interrogation parameters (window size, eccentricity, orientation, location and overlap) remains adequate in the majority of encountered problems. This dissertation proposes to go in line of a recursive approach autonomously adapting to both signal and flow conditions. Correlation window location, number and size are regulated taking into account seeding quantity and flow fluctuation magnitude. Signal quantization is based on individual particle image segmentation while spatial variance in velocity served as a heuristic for flow adaptation. The new interrogation method surpasses the compromise between spatial resolution and robustness and places more and smaller windows where the flow requires it and seeding allows it. Vice versa, less of these unnecessary small windows are placed in regions where the flow does not require it (i.e. absence of gradients or fluctuations in velocity). A variant of the spatially adaptive interrogation method is proposed that refines window size, shape, orientation and spatial distribution based on the ensemble averaged velocity field and image properties. The use of ensemble averaged properties enables the reliable application of non-isotropic resolution in contrast to the instantaneous adaptive approach where the latter is impracticable. This approach additionally allows to reduce the number of interrogation windows without overly compromising the measurement spatial resolution where needed. To cope with typical problems of PIV near interfaces, an innovative interface treatment has been proposed incorporating wall adaptivity in an automated manner by gradually increasing the sampling rate in the vicinity of the wall, rotating the correlation windows parallel to the interface and reducing wall-normal window sizes. The enhanced performances of the adaptive interrogation approach have been extensively assessed and demonstrated on a large basis of experimental flow image recordings.","PIV; image processing; adaptive interrogation; spatial resolution; aircraft wake vortex; cylinder; shock-wave boundary layer interaction; interface treatment; Fast Fourier Tranforms; correlations; vector relocation; robustness; compression rqmp; boundary layer; statistical adaptivity; non-isotropic correlation; window overlap ratio; transonic airfoil wake; data analysis; backward facing step; hypersonic sphere; over-expanded supersonic jet; statistical error; integral time scale; confidence level; dependent circular block bootstrap","en","doctoral thesis","Von Karman Institute for Fluid Dynamics","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:bd3b2294-e095-407d-bb8d-1c66f6651ae8","http://resolver.tudelft.nl/uuid:bd3b2294-e095-407d-bb8d-1c66f6651ae8","Blunt and Sharp Notch Behaviour of Glare Laminates","De Vries, T.J.","Vogelesang, L.B. (promotor); De Borst, R. (promotor)","2001","Glare laminates are materials that consist of alternating aluminium and glass prepreg layers especially designed for aeroplane structures. The result is a material that combines the properties of its constituents and the properties of a bonded structure. Some of the favourable characteristics of Glare are its fatigue, impact and fire resistance properties and the possibility to create tailored design solutions. After 25 years of development and extensive investigations within the aerospace environment, Glare is now ready to be applied for industrial production. It will be applied in large parts of the new Airbus A380 fuselage, which is planned to have its first flight in 2004. This research describes the behaviour of Glare with holes that are made within production and the behaviour when the material is damaged due to an impact like for example a bird strike or an engine seperationf what creates cracks. These holes and this damage are regarded as blunt and sharp notches respectively. The failure mechanisms that were observed are investigated and function as the basis for the development of engineering calculation methods for the blunt and sharp notch behaviour of arbitrary Glare laminates. Additional research concerning the behaviour of spliced Glare laminates in the presence of notches, the presence of a crack in a row of holes and the development of Glare with crack stoppers is presented.","glare; blunt notch; residual strength; calculation methods","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:abf9f743-ea5c-4995-9371-c0018150b0cd","http://resolver.tudelft.nl/uuid:abf9f743-ea5c-4995-9371-c0018150b0cd","Solution Space-based Approach to Assess Sector Complexity in Air Traffic Control","Abdul Rahman, S.M.B.","Mulder, M. (promotor); Van Paassen, M. (promotor)","2014","Various methods have been introduced in the past in efforts to optimize airspace sector design and the allocation of air traffic controllers. This is done with the aim to accommodate growth, increase productivity and most importantly to ensure safety of air traffic. To accomplish this, a more comprehensive understanding of human workload, especially that of the controllers involved, is required. In Air Traffic Control (ATC), there exists a maximum number of aircraft per sector that the Air Traffic Controller (ATCO) is assumed to be capable of controlling simultaneously. The maximum controllable traffic is gathered based on experimentation and subjective assessments of controller workload, which are sector specific. This threshold is not to be exceeded in order to maintain a reasonable and sustainable level of workload. However, a sector complexity metric based on the maximum number of aircraft does not consider the dynamic nature of air traffic, thus limiting the possibility of accommodating the growth of air traffic. Consequently, to better support strategic decisions that need information on ATC workload, we need better measures than just the number of aircraft. Metrics, for example the Dynamic Density (DD) that use a weighted combination of static and dynamic airspace properties, such as the number of aircraft flying through a sector, the ratio of climbing, cruising and descending aircraft, the horizontal proximity between aircraft et cetera, have been constructed and proposed as a sector complexity measure. The proposed weightings are determined through regression analysis on expert judgement for a particular sector design. As a result, these metrics become highly dependent on sector and operator-centered factors and therefore not uniformly applicable to a wider range of operators and sector designs. A careful calibration would then be needed to tailor the measure to each individual operator and also to the considered sector. In an effort to find a more objective measure of sector complexity and a predictor of workload, this thesis investigates a constraint-based measure based on the Solution Space Diagram (SSD). In essence, the SSD is a method to observe aircraft restrictions and opportunities to resolve air traffic conflicts in both the speed and heading dimensions. The SSD can be described as the available control area for the controlled aircraft in respect to other observed aircraft within the vicinity. The construction of the SSD is based on the projection of the ‘zone of conflict’ of the observed aircraft where the key constraint is the 5 NM separation minimum between aircraft. When considering the SSD for any individual aircraft, all neighboring aircraft introduce a ‘no-go area’ or ‘zone of conflict’ on the SSD. Intrusion of this zone is called a conflict, or, loss of separation. Looking at the results of the numerous off-line and real-time human-in-the-loop experiments, the proposed SSD metric shows a promising prospect of being an objective measure of sector complexity and a viable subjective workload predictor. However, these results are based on specific experiment settings, assumptions, and simplifications that were made throughout the research. Thus, to prove that the method was found to be the most suited metric in measuring sector complexity, a more extensive research regarding its performance and robustness should be done in the future. More comprehensive research on sector complexity has to be done in order to have a better understanding of sector complexity and controller workload. Also, to keep up with the relevance of the current situation, the extension of the SSD to the third dimension is crucial.","air traffic management; constraint-based visualisation; workload; sector complexity; air traffic controller; air traffic control","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:53bcad8d-46e6-4e0b-abb3-bf51a6032d7c","http://resolver.tudelft.nl/uuid:53bcad8d-46e6-4e0b-abb3-bf51a6032d7c","Multi-Scale Modelling of Fatigue of Wind Turbine Rotor Blade Composites","Qian, C.","Gürdal, Z. (promotor)","2013","In this research, extensive fatigue tests were performed on single glass fibres and composite coupons. Comparison of the test results shows that there is a significant difference between the fibre and composite fatigue behaviour. In order to clarify this difference, a multi-scale micro-mechanical model was developed. This model predicts fatigue properties of composite coupons based on results from experiments on isolated fibres and matrix material. The model predicts the behaviour of small composite samples. The difference between theory and practice is due to exclusion of some of the failure modes observed in a realistic laminate, such as fibre-matrix-debonding and delamination. Nevertheless, stiffness degradation is well predicted.","Multi-Scale Modelling; Micro-mechanical Modelling; Fatigue; FRP Composites","en","doctoral thesis","","","","","","","","2013-04-22","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:1315d027-75d2-4355-9e5e-c60a61e255e3","http://resolver.tudelft.nl/uuid:1315d027-75d2-4355-9e5e-c60a61e255e3","Lifetime Modeling of Thermal Barrier Coatings","Hille, T.S.","De Borst, R. (promotor); Turteltaub, S.R. (promotor)","2009","Thermal barrier coatings (TBCs) are applied in gas turbines to enhance their thermal efficiency by isolating the metallic components from the aggressive hot gas. TBC lifetime is limited by damage processes originating at internal interfaces, which may ultimately lead to delamination and spallation. In the present thesis constitutive models are presented for the coating components and the most detrimental failure mechanisms. To simulate the thermomechanical failure response, the numerical models are applied to boundary value problems representative of conditions typically encountered during service and/or experiments. Based on the results, recommendations are given for TBC manufacturing.","thermal barrier coatings; lifetime modeling; cohesive zone law; fracture mechanics; partition of unity method","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures and Materials","","","",""
"uuid:808f8eb8-43e7-4c69-b20d-f68e75c07b7a","http://resolver.tudelft.nl/uuid:808f8eb8-43e7-4c69-b20d-f68e75c07b7a","Multi-fidelity methods for fluid-structure interaction and uncertainty quantification","Scholcz, T.P.","Bijl, H. (promotor)","2015","The cost and turnaround time of the load calculation cycle in the design process of aircraft can be reduced by developing new numerical simulation technologies aimed at efficient prediction of steady and unsteady force coefficients in the flight envelope. In order to capture the most extreme stress levels due to gust and manoeuvres, efficient time-accurate analysis of fluid-structure interaction is desired. In order to incorporate uncertainties in flight conditions, manoeuvres, shape and material properties, efficient uncertainty quantification is desired. This thesis aims at developing efficient multi-fidelity algorithms for fluid-structure interaction and uncertainty quantification. Space-mapping is a multi-fidelity technique that can be applied in order to accelerate strongly coupled partitioned fluid-structure interaction. Gradient-Enhanced Kriging is a response surface technique that can be used for uncertainty quantification. Aggressive Space-Mapping is applied to three academic fluid-structure interaction problems of increasing complexity. For most test cases considered the estimated and observed speedup with respect to the Quasi-Newton algorithm is larger than 1. The influence of the timestep size on the speedup is large compared to other parameters. In case of compressible flows the speedup can rise to 1.5 for large time-steps. In case of incompressible flows higher speedups can be expected due to strong coupling of the fluid-structure interaction. Gradient-Enhanced Kriging (GEK) is applied to two academic uncertainty quantification problems of increasing complexity. The observed speedup of GEK with respect to Kriging increases with the number of dimensions of the design-space. When the gradients are computed with the adjoint method the theoretical speedup is S = (1+d)/2, where d is the number of dimensions. The observed speedup and theoretical speedup are only close if the derivative noise, variation of the sampling plan and the variation of the target accuracies are taken into account.","multi-fidelity; uncertainty quantification; fluid-structure interaction; space-mapping; kriging; adjoints; non-intrusive","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:c85e8096-48ad-47d6-944b-d9f99f358b5a","http://resolver.tudelft.nl/uuid:c85e8096-48ad-47d6-944b-d9f99f358b5a","Study of Delft aerospace alumni","Smits, G.N.","Gurdal, Z. (promotor); De Graaff, E. (promotor)","2008","This thesis reports on an alumni study of the Faculty Aerospace Engineering at Delft University of Technology to discover what the impact is of the degree in aerospace engineering on an alumnus' professional success and comment on what are important qualities for aerospace engineers to have in order to differentiate themselves from those with an average career. Based on a literature survey and feedback of an expert panel a list of 12 competencies, deemed important for the professional success of alumni, was developed. These competencies are: the ability to synthesize, analyticalskills, problem solving skills, people and operational management skills, oral and written communication skills,networking skills, broad technical knowledge, specialist technical knowledge, ability for life-long learning and the ability to work in teams. It was also discovered in literature that there are two principal career tracks of aerospace engineers: that of the engineering specialist and that of the engineering manager. The success definitions used were: level of job responsibility, salary with respect to work experience and salary with respect to work experience and level of job responsibility.The results of the questionnaire showed that the aerospace alumni do well and are very satisfied with their degree.The results of the survey showed that all 12 competencies were important to a certain degree for an alumnus' current job. No significant relationship however, was found, between the contribution of aerospace engineering to the competencies and professional success. Alumni also indicated that they deem themselves less capable in people and operational management skills as well as networking skills. The results also showed that having good specialist technical knowledge does contribute to more job responsibility but not necessarily to more salary. Furthermore it was found that the alumnis' ability in people and operational management skills have a positive influence on their professional success.The thesis also contains recommendation with regards to the implementation of the competencies in aerospace engineering curricula.","engineering education; higher education; aerospace engineering; alumni; success","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:99ed4de4-f068-467f-970c-5d903bfc4a2a","http://resolver.tudelft.nl/uuid:99ed4de4-f068-467f-970c-5d903bfc4a2a","Wave Propagation in Thin-walled Composite Structures: Application to Structural Health Monitoring","Pahlavan, L.","Gürdal, Z. (promotor)","2012","In order for the increased use of fiber-reinforced composite structures to be financially feasible, employment of reliable and economical systems to detect damage and evaluate structural integrity is necessary. This task has traditionally been performed using off-line non-destructive testing (NDT) techniques. Safety enhancement programs and cost minimization schemes for repairs, however, have substantially increased the demand for real time integrity monitoring systems, i.e. structural health monitoring (SHM) systems, in the past few years. The real time feature imposes an additional constraint on SHM systems to be fast and computationally efficient. Among the existing approaches fulfilling these requirements, guided ultrasonic wave (GUW)-based methods are of particular interest, since they provide the possibility of finding small size defects, both at the surface and internal, and covering relatively large areas with reasonable hardware costs. Next to theses appealing features, there are certain complexities in utilizing GUWs for SHM of fiber-reinforced composites, that mainly arise from the multi-layer, anisotropic, and non-homogeneous nature of the material. In addition, the multi-mode character of GUWs further increases the complexity of the SHM problem in these materials. It is believed that computationally efficient methods for simulation of GUWs in composite structures can substantially contribute to the field of SHM. Such numerical tools do not only improve the understanding of the propagation of ultrasonic waves and their interaction with different damage types and boundary conditions, but can also make model-based damage identification techniques feasible in the context of on-line SHM. In this dissertation an improved framework for simulation of GUWs in composite structures is developed. The improvements are mainly brought about through the use of (i) physical constraints that reduces the dimensionality of the problem, (ii) improved approximation bases for spatial and temporal discretization of the governing equations, and (iii) efficient mathematical tools to enable the possibility of parallel computation. The formulated approach is a wavelet-based spectral finite element method (WSFEM), which offers the possibility of complete decoupling of the spatial and temporal discretization schemes, and results in parallel implementation of the temporal solution. Although the concept of the WSFEM was introduced a few years prior to this research, to the author's best knowledge, no general framework was proposed for dealing with 2D and 3D problems with inhomogeneity, anisotropy, geometrical complexity, and arbitrary boundary conditions. These issues are addressed in this dissertation in multiple steps as described below. 1- Improvement of the temporal discretization using compactly-supported wavelets, by computing the operators of the wavelet-Galerkin method over finite intervals, and demonstrating about 50% reduction in the number of sampling points, with the same accuracy, compared to the conventional wavelet-based approach. 2- Extension of the existing formulation of the 1D WSFEM based on an in-plane displacement field to 1D waveguides based on a 3D displacement field. In the 1D finite element formulation, spectral shape functions are employed which satisfy the governing equations, in which shear deformation and thickness contraction effects are also incorporated. The minimum number of elements for modeling 1D waveguides is used in this approach. 3- Formulation of a novel 2D WSFEM in which frequency-dependent basis functions are suggested for spatial discretization. Contrary to the conventional WSFEM, the presented scheme discretizes the spatial domain with 2D elements and does not require extra treatments for non-periodic boundary conditions. Superior properties of the formulation are shown in comparison with some time domain FEM schemes. 4- Generalization of the WSFEM and extension to 3D geometries. It is demonstrated that the standard spatial discretization schemes can be combined with the wavelet-Galerkin approach, to fully parallelize the temporal solution. A higher-order pseudo-spectral finite element method, i.e. spectral element method (SEM), is further adopted to attain spectral convergence properties over space and time. The developed WSFEM is subsequently employed in the passive time reversal (TR) method, which is a model-based approach for detection of load and damage location, and operates based on the time invariance of linear elastodynamic equations. It is shown that using the passive TR scheme, the problem of load and damage detection, which is essentially an inverse problem, can be solved in the form of a forward problem, thereby alleviating uniqueness and stability issues. A number of case studies and examples, numerical and experimental, are presented throughout this dissertation to better demonstrate the applicability of the proposed framework.","composite materials; guided waves; ultrasonics; structural health monitoring; wavelets; wavelet-Galerkin; time reversal; damage detection","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Computational Mechanics","","","",""
"uuid:2d35b396-5859-465b-a224-5d3ff0c88ada","http://resolver.tudelft.nl/uuid:2d35b396-5859-465b-a224-5d3ff0c88ada","Nonlinear mode interaction for thin imperfect anisotropic circular cylindrical shells under different loading conditions","Notenboom, R.P.","Arbocz, J. (promotor)","2006","Abstract not available","buckling; cylindrical shells","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d349ac8f-b91a-43ea-a33b-2b86d3235293","http://resolver.tudelft.nl/uuid:d349ac8f-b91a-43ea-a33b-2b86d3235293","Development of a Robotics-based Satellites Docking Simulator","Zebenay, M.","Gill, E.K.A. (promotor); Choukroun, D. (promotor)","2014","The European Proximity Operation Simulator (EPOS) is a hardware-in-the-loop (HIL) system aiming, among other objectives, at emulating on-orbit docking of spacecraft for verification and validation of the docking phase. This HIL docking simulator set-up essentially consists of docking interfaces, simulating the servicing satellite called chaser satellite, the serviced satellite called target satellite, a sensor of the forces and torques during contact, and two industrial robots that hold the docking interfaces, and control satellites motion relative position and attitude. Furthermore, the EPOS includes a real-time controller interface linked to a computer-based numerical simulator of satellites orbital and attitude dynamics. A key feature of this set-up is the feedback loop that is closed on the real force sensed at the docking interfaces during contact. That feedback force is used as driving input to satellites dynamics numerical simulation. This HIL docking simulation concept has the unique advantage of using the measured contact forces and torques, but it presents significant challenges. The high stiffness of the industrial robots and the docking interfaces yields a high bandwidth contact dynamics at impact and, thus, very short contact time durations. These times might be shorter than the inherent time delay of the robot controllers. This leads to physical inconsistency in the docking dynamics and measured variables. This also causes a stability issue in the force feedback HIL system during contact and may cause catastrophic damages to the robots. Additional problems that need to be addressed are the characterization of the stability domain of operation, the compensation of the non-contact forces and torques, such as the measured forces and torques due to gravity effect. Finally, this thesis addresses the task of identifying the dynamic behavior of the robot end-effectors. This thesis addresses the above mentioned challenges and problems and presents solutions towards a stable and safe docking simulation operation of the EPOS facility. First, in order to mitigate the high stiffness and time delay problem, the thesis introduces a novel idea of simulating contact based on a concept called hybrid contact dynamics model. The method, developed in this thesis, is based on a combination of a passive compliance control introduced at the end-effector of the robot and a virtual contact model. The virtual contact model allows the operator to vary the contact parameters which can also be used as a control gain. The method also allows to solve the stability problem coming from the combination of time delay of the robot controller and high stiffness of the robot end-effector. For the passive compliance control, a new device is designed that has fairly known stiffness properties which are softer than the robot and docking interface stiffness. Second, the thesis presents a stability analysis of the proposed method via the adaptation of the pole location method to dead-time systems. The analysis is based on a linearized design model of the dynamics; linearization is performed around the docking geometrical configuration. This work first presents an analysis for the single dimensional case, which is then extended to two dimensions. The highlight of the stability analysis is the development of physically intuitive state-space model that easily unveil the modes of the contact dynamics. The application of the pole location method to the resulting second-order characteristics polynomial is straight forward. The contribution of this analysis is a closed-form relationship, and associated plots, among the system's parameter, i.e., the satellite's masses, the stiffness and damping coefficient of the contact parameters, the delay, and the geometry. In addition, the stability analysis is supported using the passivity method which is valid for three dimensions. Third, a model of the force-torque sensor is presented, and the classical weighted least-squares estimation technique is suggested for the identification and compensation of the non-contact forces and torques from the contact force and the torque measurement. Finally, it is proposed to utilize a LEICA laser tracker, a positioning measurement system, in order to identify the robot end-effectors dynamics behaviors such as the natural frequency and damping ratio. This hybrid contact dynamics model and the accompanying analysis is envisioned as a tool for safe and flexible EPOS operations. This tool shall allow emulation of the desired impact dynamics for any stiffness and damping characteristics within the stability region without recurring to a modification of the hardware. The experimental results of the robotics based hybrid docking simulator comply with experimental data from an air-bearing testbed that was independently performed by this author at the Space Robotics Laboratory of Tohoku University. It demonstrates the validity of the novel EPOS concept of operations and increases the confidence of using this approach for future on-orbit docking/contact algorithm validation, at the EPOS facility.","","en","doctoral thesis","","","","","","","","2014-03-17","Aerospace Engineering","Space Systems Engineering","","","",""
"uuid:68fd89ff-aad6-4ad8-b280-d2fe8b500d48","http://resolver.tudelft.nl/uuid:68fd89ff-aad6-4ad8-b280-d2fe8b500d48","Adaptive Backstepping Control and Safety Analysis for Modern Fighter Aircraft","Van Oort, E.R.","Mulder, J.A. (promotor); Chu, Q.P. (promotor)","2011","There exist many examples of aircraft incidents in which the pilots have successfully used the remaining control authority over an aircraft to save the airframe and its passengers and cargo from apparently hopeless failure conditions. Unfortunately, the opposite is also true. Several accidents happened in which the crew was not able to save the aircraft, although post-flight analysis showed that it was possible with alternative, perhaps unconventional, control strategies. These aircraft accidents indicate that there is a potential benefit of fault tolerant flight control techniques, which are able to accommodate changes in the aircraft’s dynamics due to damage to the aircraft and failures of its systems. In this dissertation a modular adaptive flight control approach was developed based on adaptive backstepping with a recursive least squares estimator. The proposed control design was evaluated in numerical simulations on high-fidelity fighter aircraft models. The performance has been compared in simulation scenarios at several flight conditions with the aircraft model suffering from actuator failures, longitudinal center of gravity shifts and changes in aerodynamic coefficients. Results of the simulations demonstrate that the adaptive flight controller provides a significant performance improvement over classical, non-adaptive flight control designs. Although adaptive flight control techniques have shown that it may be possible to stabilize a damaged aircraft for a variety of faults and failures, it is still unclear what maneuvers are still possible and how much the performance of the aircraft has degraded due to these faults and failures. The safe flight envelope is defined as the region in the state space for which safe operation of the aircraft, and safety of its cargo and passengers can be guaranteed. In this dissertation the level set method was researched to determine the safe region of operation of the aircraft. Application of this method to an F-16 model at different flight conditions showed shrinking of the safe flight envelope and decreased maneuverability with decreasing dynamic pressure.","adaptive control; identification; aircraft; safety; nonlinear control; level set","en","doctoral thesis","","","","","","","","2011-04-06","Aerospace Engineering","Control and Simulation","","","",""
"uuid:fceebee1-425e-401a-b567-9ad4ecf6468d","http://resolver.tudelft.nl/uuid:fceebee1-425e-401a-b567-9ad4ecf6468d","Multidisciplinary design optimization of a second-generation supersonic transport aircraft using a hybrid genetic/gradient-guided algorithm.","Bos, A.H.W.","Torenbeek, E. (promotor)","1996","","multidisciplinary design optimization; supersonic transport aircraft; genetic algorithms","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:056f2e52-45ba-4dd8-a63b-dcda33ad0e20","http://resolver.tudelft.nl/uuid:056f2e52-45ba-4dd8-a63b-dcda33ad0e20","Multiscale and probabilistic modelling of micro electromechanical systems","Verhoosel, C.V.","De Borst, R. (promotor); Gutierrez, M.A. (promotor)","2009","Micro electromechanical systems (MEMS) are nowadays used in many applications, such as airbag accelerometers and inkjet printer heads. With the number of applications growing, the need for advanced numerical tools to aid in the design of MEMS increases. The development of such tools is far from trivial, since numerical modelling of MEMS poses various challenges, such as the simulation of multiphysical effects, multiscale effects and effects of microstructural randomness. In this dissertation, computational techniques have been developed to asses the reliability of MEMS. More specifically, a cohesive zone formulation has been used to mimic crack growth in piezoelectric continua. A multiphysical finite element model has been developed to correctly simulate the electromechanical coupling in such materials. A computational homogenisation method has been proposed to efficiently incorporate microstructural effects in a macroscale analysis. Stochastic finite element methods have been employed to include the effects of microstructural imperfections on the behaviour of MEMS.","multiscale modelling; cohesive zone modelling; partition of unity method; stochastic finite element methods; micro electromechanical systems","en","doctoral thesis","","","","","","","","2009-10-12","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:17141fd7-5645-4ce3-b480-d706d58b36ba","http://resolver.tudelft.nl/uuid:17141fd7-5645-4ce3-b480-d706d58b36ba","Quasi homogeneous approximations for the calculation of wings with curved subsonic leading edges flying at supersonic speeds","Coene, R.","Steketee, J.A. (promotor)","1973","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e5587f19-20f6-43c0-8aeb-50185dbc6fc9","http://resolver.tudelft.nl/uuid:e5587f19-20f6-43c0-8aeb-50185dbc6fc9","Enabling Continuous Descent Operations in High-Density Traffic","De Leege, A.M.P.","Mulder, M. (promotor)","2013","The Air Traffic Management (ATM) community strives to reduce the environmental impact per flight. Continuous Descent Operation (CDO) has been identified by the ATM community as one of the operational improvements that could reduce aviation’s environmental impact, both in terms of aircraft noise and gaseous emissions. In the current ATM system, CDOs are only feasible in low-density traffic. The ultimate goal is an ATM system that facilitates CDOs in high-density traffic. This research described in this thesis focused on two features of such an ATM system: decision support that enables the air traffic controller to accurately set up traffic for CDO, and delegation of the spacing task to the flight crew during the CDO. Two enablers are real-time availability of meteorological data, and accurate trajectory prediction. In this thesis new methods were developed and validated to infer wind, air pressure, and air temperature profiles from aircraft surveillance data. Trajectory prediction was defined as a machine learning problem, enabling predictions based on historic aircraft trajectory and meteorological data without the need for explicit modeling of the aircraft performance and procedures. A decision support tool was developed further and tested using a human-in-the-loop experiment. The tool enabled the subjects to set up traffic for CDO in high-density traffic at an acceptable work load level and high level of situation awareness. Monte-Carlo simulations were carried out to assess the runway capacity that can be achieved when delegating the spacing task to the flight crew. These simulations showed the feasibility of CDOs in high-density traffic.","Air Traffic Management; Air Traffic Control; Continuous Descent Operation; Continuous Descent Approach; Aircraft; Trajectory Prediction; Time-Space Diagram; Self-Spacing","en","doctoral thesis","","","","","","","","2013-07-11","Aerospace Engineering","Control and Simulation","","","",""
"uuid:913e3d33-1db9-4e9f-9e00-1a38a3f40eb0","http://resolver.tudelft.nl/uuid:913e3d33-1db9-4e9f-9e00-1a38a3f40eb0","Processing and Application of ICESat Large Footprint Full Waveform Laser Range Data","Duong, V.H.","Vosselman, M.G. (promotor); Teunissen, P.J.G. (promotor)","2010","In the last two decades, laser scanning systems made the transition from scientific research to the commercial market. Laser scanning has a large variety of applications such as digital elevation models, forest inventory and man-made object reconstruction, and became the most required input data for flood plain and hydraulic models. This system is generally called as a discrete laser scanning system. A discrete laser scanning system sends a pulse to the ground surface and records the return signal resulting from the illumination of the surface. The area of the illuminated surface is defined as the footprint size of the laser shot. The two-way travel time of the laser pulse allows to determine the distance of the laser system to the surface. Traditional systems are unable to record the complete return signal, but typically store only one to four distances to objects in the laser footprint. A new system developed to overcome the above limitations is the so-called full waveform scanning system. The system sends out a pulse of a certain width and amplitude. After reflection of the pulse on the objects surface, the system records the complete returning pulse signal. This complete signal is the so-called full waveform. Compared to traditional scanning systems, a full waveform system retrieves more information that should still be extracted though from the waveform shape. The shape of the full waveform contains information on the characteristics of the illuminated footprint, like object information (tree and building height), forest structure and ground surface characteristics (e.g. forest species surface roughness and slope) as well as a land cover type (water, bare earth, or urban areas). Harding (1998), and Blair et al. (1999) showed that using observations from a full waveform laser system it is possible to achieve accurate forest structure and biomass estimates. However, the system considered in this case was just operated from an airplane flying at a low altitude of a few kilometers above the ground surface with a medium footprint size of about 10-20 m. Moreover, data acquisition could only be performed in a small area. Some typical systems used in these days were the Scanning Lidar Imager of Canopies by Echo Recovery system (SLICER), the Laser Vegetation Imaging Sensor (LVIS), and the commercial airborne full waveform scanning system from RIEGL the LMS-Q560 (2003). In 2003, moreover, NASA launched the first satellite full waveform system, the so-called Ice Cloud and land Elevation Satellite system (ICESat), carrying the Geoscience Laser Altimetry System (GLAS) instrument. The purpose of ICESat was to collect, among others, measurements concerning the Antarctica and Greenland ice sheets and their mass balance, concerning land vegetation and concerning the atmosphere. This space borne system acquired data between 2003 and 2009 over the entire earth from 600 km altitude, with a footprint size of about 70 m and a distance between consecutive footprints of approximately 175 m. However, due to for example the high operational altitude, this system was also affected by many error sources, like instrumental and operational problems, atmospheric effects and surface conditions. Processing such data is a challenging task; and development of a validation method together with the development of new applications of large footprint full waveform data are the main targets of my thesis work. For this purpose, the contents of this thesis is organized in six chapters In chapter 1, the background and scope of the research is introduced. In chapter 2, full waveform sensor and instrument development is presented. The main content starts in chapter 3. This chapter focuses on processing and parameterization of large footprint ICESat full waveform data. Data handling is described in detail. It is presented how a pulse interacts to objects on the earth surface and what information a return pulse contains. Moreover, it is shown how waveform parameters can be obtained by fitting a number of Gaussian numbers to a waveform using least squares. waveform in a sense of least square estimation. Two alternative methods to obtain information on waveforms, i.e. waveform deconvolution and waveform simulation were also implemented and are discussed. At the end of this chapter, an overview is given of waveform parameters and their possible physical interpretation and application. This chapter aims to provide a tutorial to wider audiences/readers who would like to use satellite laser full waveform data for their own purpose. In order to evaluate the accuracy and the precision of elevation and height estimates that can be obtained using the ICESat full waveform system, the topic of validation is studied in chapter 4. In this chapter, first background and related work are discussed. Two validating cases discussed in detail : (i) Comparison between the bare land elevations derived from ICESat full waveform data and airborne laser scanning data over The Netherlands; and (ii) Identification and investigation of error sources of the ICESat full waveform system by comparing waveform pairs that have overlapping footprints. For the first validation case, filtering constraints have been investigated and further developed to avoid influence of data anomalies. Examples of factors having a negative influence on a comparison include on one hand waveforms affected by saturation or cloudy conditions and on the other hand footprints that are not covered well by the available airborne data points The comparison between ICESat and accurate airborne laser data over The Netherlands confirms that the ICESat full waveform accuracy and precision strongly depends on land cover type. With respect to different land cover type, the accuracy was about -21 cm with a standard deviation of about 20 cm over bare earth. The accuracy was -24 cm with a standard deviation of 28 cm over urban areas and -9 cm with a largest standard deviation of about 45 cm over forest. As expected, the accuracy decreases when the complexity of the surface increases (e.g. from bare land to urban)). The accuracy of ICESat derived elevations over water could not be assessed because of few effects: changes in water level, lack of airborne data points over water surfaces, etc., It is concluded that if a) proper filtering is applied, and b) the terrain relief is small, the last mode of an ICESat waveform represents the terrain/bare land height with both an accuracy and precision at the decimeter level. Also feature height estimation of features like trees or buildings were studied. The difference between ICESat and airborne derived feature heights are acceptable over forested and bare land areas. However, the result over buildings are not satisfactory. The main reason is that ICESat derived feature height estimations are sensitive to feature height variations occurring at spatial distances smaller than the size of the ICESat footprints. For features that are homogeneous at the scale of ICESat footprints, ICESat waveform analysis is a suitable method for estimating feature heights. For urban environments, incorporation of an additionally accurate Digital Elevation Model might still enable the monitoring of feature height changes. For the second validation case a database was constructed, consisting of more than one hundred thousand (>100000) repeated, partly overlapping ICESat waveforms over Europe. The aim is to identify the cause of changes in waveform parameters obtained from (partly) overlaying waveforms Even in such a size of database it turned out almost impossible to identify suited waveform pairs. The first problem was the lack of almost completely overlaying footprints, and second, the lack of waveform pairs situated at stable areas. Unfortunately, the number of almost completely overlapping footprints from repeated ICESat measurements that could be obtained from campaign L1 to L3e in the region between 36N and 71N latitude and 11W and 33E longitude was very limited. Performing a full worldwide search over all campaigns is however expected to result in a quite large data set of suitable almost perfectly overlapping repeated footprints. Such data set could therefore be used to identify and resolve remaining ICESat processing issues. After applying all corrections identified in the calibration/validation procedure, the ICESat product is ready to be used in different applications considering the surface of the Earth. How to develop applications by using large footprint full waveform data is discussed in chapter 5. By considering the full waveform parameters derived from the waveform processing procedures of chapter 3, two applications of ICESat full waveform data were studied in detail. A new contribution described in this chapter compares repeated ICESat waveform pairs to assess forest change. By analyzing corresponding waveforms acquired in different campaigns at nearly coinciding footprints, canopy changes caused by seasonal influences were detected. A general new aspect introduced in this chapter is to analyze waveform parameters in terms of a pair of full waveforms that were acquired at approximately the same location. Comparison of the waveform parameters of such pairs not only allows the detection of seasonal influences on forest type, it may also become possible to further detect and estimate important forest change parameters, like forest growth and deforestation. As a first step seasonal changes over broadleaf, mixed-wood, and needleleaf forests between winter and summer epochs of 2003, along near-coincident ground tracks were quantified. It was found that although the maximum tree height barely changes over 6 months, i.e., less than 2.2% for the three forest types, a suited waveform parameter can detect forest canopy change mostly for broadleaf (a 148% change, winter to summer) and less for conifers (a 36% change). Alternative waveform parameters to describe forest changes are also discussed. An application of the seasonal change in waveform parameters is to use these parameters to classify footprint areas directly into forest type classes. Preliminary results, with a kappa value of 0.57, provide a baseline against which improvements in both data and methodology can be gauged in future. Future work should include a method for correcting slope-induced changes in the waveform results, both for individual waveforms and for waveform pairs. In addition, further improvement is expected by including a neighbourhood analysis, that is by incorporating spatial correlation between close by waveforms and their changes. An individual quality descriptor of the tree parameter values could be obtained by quantifying and propagating errors encountered during the waveform processing. Moreover, tree parameter values should be validated against either data from field measurements or data from other sensors. Finally, the parameter definitions should be refined and validated in order to improve agreement with biophysical characteristics of the forest. In the second application, it is demonstrated how ICESat full waveforms can be used for land cover classification. It was the first time that the possibility of using ICESat data for this purpose was investigated. Over The Netherlands, ICESat footprint locations were classified into four classes: high vegetation (high trees or forest), urban, water, and bare land/low vegetation. The following waveform parameters were used as class attributes: return energy, waveform extent, waveform start and number of Gaussian components. It is concluded that the accuracy of classification equals 73% in comparison to a confusion matrix based on the CORINE land cover database 2000 (CLC2000) covering the same study area. In addition, it is shown that ICESat waveforms could be used to build a feature vector consisting of suited waveform parameters that can be consecutively applied to classify the land cover class of the footprint location. The full waveform parameters derived from chapter 3 together with total return energy able to discriminate between high vegetation, urban areas, bare land/low vegetation and water. This result showed the feasibility of land cover classification with spaceborne lasers. As the ICESat satellite has a near polar orbit, coverage is global, but still a main disadvantage of ICESat data is that only tracks were mapped. With the development of new systems, an area-wise coverage may become possible in future. In that case, automatic classification of large footprint full coverage full waveform laser data may lead to land cover classification results of the same high quality as can be obtained from optical data. At the end of the thesis, significant information is summarized and remaining steps but also potential new applications are described.","ICESat full waveform; airborne laser scanner; forestry; land cover","en","doctoral thesis","Delft University of Technology","","","","","","","","Aerospace Engineering","DEOS","","","",""
"uuid:703da5c9-7259-4971-8d8c-7f5439f36402","http://resolver.tudelft.nl/uuid:703da5c9-7259-4971-8d8c-7f5439f36402","Developments in the Use of Failure Rate Data and Reliability Prediction Methods for Hardware","Smith, D.J.","Smit, K. (promotor)","2000","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:be00fb31-71cb-4859-ab79-67879caadc3c","http://resolver.tudelft.nl/uuid:be00fb31-71cb-4859-ab79-67879caadc3c","Instantaneous planar pressure determination from particle image velocimetry","De Kat, R.","Scarano, F. (promotor)","2012","Forces on flapping or rotating wings, like flapping wings of micro air vehicles or blades of wind turbines are of great interest to engineers. To investigate the ways birds and insects fly, forces created by flapping wings are of importance to biologists. The pressure field, combined with the velocity field, gives a complete description of the (incompressible) flow dynamics. Furthermore the pressure field is the main contributor to the aerodynamic loading of bodies immersed in the fluid. Traditional techniques to determine pressure and forces rely on the determination of surface pressure and integral loads by point pressure and force balance measurements. In situations where it is difficult (or impossible) to instrument the body, using particle image velocimetry (PIV) velocity data to determine forces and pressure poses an interesting alternative to the existing approaches to determine sectional loading.","","en","doctoral thesis","","","","","","","","2012-03-01","Aerospace Engineering","Aerodynamics","","","",""
"uuid:c5da3e45-427b-4ff8-b4ba-0b587afe504c","http://resolver.tudelft.nl/uuid:c5da3e45-427b-4ff8-b4ba-0b587afe504c","Unsteady Characteristics of Laminar Separation Bubbles; An Experimental and Numerical Investigation","Baragona, M.","Bakker, P.G. (promotor); Van Tooren, M.J.L. (promotor); Bijl, H. (promotor)","2004","Laminar separation bubbles may occur in a wide range of engineering applications such as turbomachinery flows, wind turbines, hydrofoils etc. Much attention has been given to their effect on the flow over airfoils because of the importance for an accurate prediction of lift, drag and heat transfer. In the aeronautical world, laminar separation bubbles have traditionally been of con- cern for the aerodynamics of sailplanes and of small aircrafts. However, recent measurements stress their importance for commercial transport aircrafts in slow flight, where laminar bubbles strongly affect the flow on high-lift devices. In spite of their importance for the global characteristics of the flow, the prediction of the behavior of laminar bubbles is still not satisfactory, especially close to stall conditions. The main objective of this thesis is to investigate the unsteady features of laminar separation bubbles with the ultimate goal of an improved prediction of their behavior during the design process, especially close to stall conditions. This objective was defined during the first part of the investigation, when the stalling behavior of a multi-element slotted high-lift configuration was analyzed. The experimental investigation of this multi-element configuration clearly showed the importance of a correct prediction of the bursting of the bubble present on the flap. This bursting determined in fact the stalling characteristics of the whole configuration. Existing design tools proved inadequate to the task of predicting bursting occurrence. Furthermore, Navier-Stokes calculations of the multi-element con¯guration showed that unsteady effects were crucial in order to predict successfully the behavior of the bubble.","","en","doctoral thesis","DUP Science","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c84217a2-967c-45c4-85cb-a1630590b926","http://resolver.tudelft.nl/uuid:c84217a2-967c-45c4-85cb-a1630590b926","The integration of spaceborne accelerometry in the precise orbit determination of low-flying satellites","Van Helleputte, T.","Ambrosius, B.A.C. (promotor)","2011","This dissertation describes the integration of accelerometer measurements of LEO-satellites in GPS-based orbit determination.","orbit determination; GPS; accelerometry","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:3fe6203d-ba64-457b-916f-d05817d42816","http://resolver.tudelft.nl/uuid:3fe6203d-ba64-457b-916f-d05817d42816","Design and Properties of SWCNT-Polyetherimide Nanocomposites","Hegde, M.","Dingemans, T.J. (promotor)","2014","The main objective of the research presented in the thesis is to explore non-functionalized single-walled carbon nanotubes (SWCNTs) as reinforcing nanofiller in all-aromatic thermoplastic poly(etherimide)s. The role of polymer geometry and how this affects the morphological and thermo-mechanical properties of the SWCNT-PEI nanocomposites were investigated. The inclusion of SWCNTs in aBPDA-P3, an amorphous non-linear polyetherimide matrix had no effect on the morphology and thermo-mechanical properties of the matrix. In ODPA-P3, a more linear amorphous polyetherimide matrix, the SWCNTs act as a nucleating agent with the polymer crystallinity increasing linearly with SWCNT content to 45% (at 2.4 vol.% SWCNT). TEM measurements showed that the SWCNTs become embedded within the crystal lattice of the polymer matrix. The result is a significant increase in thermo-mechanical properties; the storage modulus (E’) above Tg increased by a factor 105 GPa and the elastic modulus from stress-strain measurements increased with a reinforcement efficiency (dY/dVf) of 170 GPa. Our findings show that the polyetherimide backbone geometry determines whether the polymer is good host for SWCNTs. To investigate the role of polymer morphology on the final nanocomposite properties, we compared SWCNT nanocomposites based on amorphous ODPA-P3 with that of a semi-crystalline BPDA-P3. In semi-crystalline BPDA-P3, the SWCNTs were found to exist within the amorphous domains of the BPDA-P3 matrix. Using the Halpin-Tsai equation, the effective SWCNT modulus was found to be ~100 GPa which is significantly lower than the 640 GPa obtained for ODPA-P3 SWCNT. By application of an isothermal step above the Tm of the nanocomposites during imidization, the conversion of the crystalline ordering around the CNT to an amorphous morphology in ODPA-P3 results in a significant reduction in the reinforcement efficiency, i.e. from 170 GPa to 30 GPa. The reinforcement efficiency for semi-crystalline and amorphous BPDA-P3 nanocomposites remains constant at 30 GPa. By comparing reinforcement efficiencies of ODPA-P3 with SWCNTs residing in contrasting morphologies, we have shown that having a crystalline-SWCNT interface is critical in obtaining nanocomposites with improved thermo-mechanical performance over the neat polymer. We have also compared ODPA-P3 nanocomposites based on 0-D fullerenes (C60) with 1-D SWCNTs. The inclusion of C60 in ODPA-P3 induces crystallization (40% at 0.6 vol.%) of the polymer matrix. At 40% crystallinity, the E’ above Tg in ODPA-P3 C60 is a mere 0.01 GPa, which is substantially lower than the 1.2 GPa observed in the ODPA-P3 SWCNT nanocomposite. By comparing mechanical property improvements as a function of crystal content in the matrix, the elastic modulus of nanocomposites with 100% crystal content could be calculated and was found to be 5.8 GPa for ODPA-P3 C60 and 10.4 GPa for ODPA-P3 SWCNT. The presence of the cylindrical crystalline coating around the CNT was found to aid in stress-transfer from the matrix to the SWCNTs.","SWCNT; nancomposites; polyetherimides; thermo-mechanical properties; mechanical properties; crystallinity; debundling","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Novel Aerospace Materials","","","",""
"uuid:deca6884-68a9-4893-aa85-eb12da3ee212","http://resolver.tudelft.nl/uuid:deca6884-68a9-4893-aa85-eb12da3ee212","Investigations of three-dimensional incompressible turbulent boundary layers","Van den Berg, B.","Van Ingen, J.L. (promotor)","1976","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c1c366bd-5a36-4d85-919e-f864a5b2823b","http://resolver.tudelft.nl/uuid:c1c366bd-5a36-4d85-919e-f864a5b2823b","Surface capturing and multigrid for steady free-surface water flows","Wackers, J.","Koren, B. (promotor)","2007","Surface capturing is a technique for modelling the water surface in numerical computations of water flow: the computational grid is not deformed, a separate surface model gives the location of the water surface in the grid. Surface capturing is generally applicable and can handle complicated ship geometries. For steady flow problems, the major disadvantage is that most capturing methods do not allow the use of fast solution methods. This thesis shows that fast solution of a surface capturing model is possible. For this, a flow model is derived that consists of conservation laws only. As these equations allow coupled solution, they can be solved efficiently for steady flows. The flow equations are discretised with a finite-volume method. The convective part is discretised with linearised Riemann fluxes, which guarantee the stability of the discretisation and good performance of the relaxation methods. A RANS turbulence model is added to the system. A multigrid solver is combined with line Gauss-Seidel smoothing. The source term in the turbulence model can make the line smoothing unstable. Therefore, a local adaptive damping is added to the smoother. Also, the mixture surface model and the turbulence model cause large differences in the solutions on fine and coarse grids, so nonlinear multigrid is ineffective. Our multigrid method combines nonlinear smoothing on the finest grid with linear coarse grid corrections. The discretisation is made second-order accurate with a limited scheme. To keep the water surface sharp, a compressive limiter is used for the volume fraction, that indicates the surface. The second-order accurate equations are solved with defect correction. Results are presented for a 2D channel flow with a bottom bump. The capturing model gives good agreement with experiments and existing numerical models. The multigrid solution is up to 20 times faster than single-grid line smoothing. The thesis also contains two smaller topics: an unstructured grid refinement method for ship flow grids and a study of shock behaviour for a compressible two-fluid flow model.","surface capturing; multigrid; steady free-surface flow; line smoother; rans turbulence model; defect correction; compressive discretisation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:cddf5147-c062-4afc-af20-3165ef44f2bd","http://resolver.tudelft.nl/uuid:cddf5147-c062-4afc-af20-3165ef44f2bd","Sattelite altimeter data processing: From theory to practice","Zandbergen, R.C.A.","Wakker, K.F. (promotor); Rummel, R. (promotor)","1991","","","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6b564b35-cb74-436c-8c47-845bfbbb8b4d","http://resolver.tudelft.nl/uuid:6b564b35-cb74-436c-8c47-845bfbbb8b4d","Development of a design methodology for handling qualities excellence in fly by wire aircraft","Gibson, J.C.","Mulder, J.A. (promotor); Stassen, H.G. (promotor)","1999","","","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f8c8ad4e-5d52-4bfd-8449-2748bad26673","http://resolver.tudelft.nl/uuid:f8c8ad4e-5d52-4bfd-8449-2748bad26673","Fibre Placement Architectures for Improved Damage Tolerance","Nagelsmit, M.H.","Gürdal, Z. (promotor)","2013","Composites are notorious for their poor impact behaviour. Delaminations seriously decrease the compressive strength of the material after impact. Laminates made from woven fabric show in general more beneficial impact behaviour than laminates with unidirectional layers, but their manufacturing process is harder to automate. The new fibre placement architectures named AP-PLY combine an increased damage tolerance with an automated production process. Using fibre placement, instead of placing parallel fibre bands next to each other, room is left between bands. A second series of interspaced fibre bands is placed at an angle with respect to the first series. The remaining gaps are subsequently filled up. Adjacent plies are thus more interconnected and delamination damage is contained in a smaller area. Test results show significant improvement in compression after impact strength, delaminations are smaller and barely visible impact damage is reached at a lower impact energy level. In one of the configurations, the compressive strength after impact is increased with 15%.","composites; fibre placement; damage tolerance","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Computational Mechanics","","","",""
"uuid:ed787c31-f9de-45c6-b2da-974578d0f581","http://resolver.tudelft.nl/uuid:ed787c31-f9de-45c6-b2da-974578d0f581","Ventilation modelling of the human lung","De Jongh, F.H.C.","Steketee, J.A. (promotor); Deen, L. (promotor)","1995","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8d5017da-18e1-482c-a250-dcca8d90a443","http://resolver.tudelft.nl/uuid:8d5017da-18e1-482c-a250-dcca8d90a443","Ecological Approach to Pilot Situation Awareness","Van Dam, S.B.J.","Mulder, M. (promotor); Van Paassen, M.M. (promotor)","2014","Future air traffic concepts foresee that in unmanaged airspace, to reduce workload of air traffic controllers and the resulting constraints on capacity, the separation task will be delegated to the flight deck. Technology-driven pilot self-separation support systems have been developed that present explicit automated solutions to deal with conflicts. These systems do not offer a transparent window on the reasoning of the automation, making it difficult for pilots to judge the validity of the proposed automated solution, or come up with safe ‘good-enough’ alternatives. This thesis engaged to solve the fundamental problem of determining ‘what information’, and ‘what visual form’ would best promote pilot situation awareness (SA), to safely and effectively deal with traffic. Several prototypes for an airborne trajectory planning tool were designed and evaluated. A formative constraint-based design approach was adopted, Ecological Interface Design (EID), to create an ‘ecological’ airborne separation assistance system. The ecological approach gives priority to the worker’s environment, or ‘ecology’, focusing on how the environment imposes constraints on the worker. EID is hypothesized to improve operator SA and overall system safety when compared to normative, task-oriented, user-centered design approaches, especially in situations that were unanticipated by designers. From this thesis we conclude the following. First of all, this work has clearly shown that an ecological display, providing pilots a profound layer of information without any help of automation in terms of explicit advices, can be as safe and as effective as traditional displays that mainly present explicit automated advisories. Second, the design of ecological interfaces in domains where the abstract functions are less obvious, like the self-separation problem studied here, benefits from an incremental, evolutionary approach. Indeed, EID is not a recipe. Third, from the comparison with the more traditional design it became clear that although reducing the solution space dimension can have benefits in terms of reducing cognitive load, in the end it may lead to more cognitive load for operators to build a correct and complete mental model of the situation. Fourth, and related, although an appropriate ecologically-inspired interface can alleviate a pilot’s dependency on an explicit compelling advisory, adding dimensionality to the pilot control actions (e.g., involving more and more constraints) may render the ecological display to become too complex to be used without some sort of automated advisories. The ecological overlays developed here could be the ‘missing link’ to design a Joint Cognitive System (JCS). That is, the ecological overlays may be used to close the gap in the awareness of situations shared between automation and pilot, enabling pilots to better judge the fidelity of the proposed solution and, in case the automation fails, to come up with good-enough alternative resolutions. That is, traditional task-oriented displays and the ecological displays do not exclude each other’s use in one system. On the contrary, whereas task-oriented support may lower cognitive workload in simple standard situations through the availability of easy-to-use, automated instructions, the ecological decision support overlays show the ‘total situation’ to help the operator to become an expert and able to deal with unanticipated events. Key in this JCS design effort is to use automation as a tool to lower cognitive effort and improve decision making in such a way that it does not destroy the benefits of ecological properties of the design.","Aviation Safety; Ecological Interface Design; Automation; Separation Assistance; Human Factors; Situation Awareness; Cockpit Display; Conflict Situation; Human-Machine Interaction; Cognitive Systems Engineering; Constraint-based visualisation; Spatio-temporal; Trajectory Planning; Meaningful Physics","en","doctoral thesis","Delft University of Technology","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:480170de-89e8-49e9-9498-d988efbc684d","http://resolver.tudelft.nl/uuid:480170de-89e8-49e9-9498-d988efbc684d","Towards a New Durable and Environmentally Compliant Adhesive Bonding Process for Aluminium Alloys","Oosting, R.","Vogelesang, L.B. (promotor)","1995","","voorbehandelingen; primers; lijmen; chromaten; oplosmiddelen","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:aa2de1a2-2d36-494f-b2a4-871f51f93c00","http://resolver.tudelft.nl/uuid:aa2de1a2-2d36-494f-b2a4-871f51f93c00","All-aromatic liquid crystal thermosets and composites thereof","Iqbal, M.","Van der Zwaag, S. (promotor); Dingemans, T.J. (promotor)","2010","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:e15e7cec-4355-43f0-9137-0b4608530eb4","http://resolver.tudelft.nl/uuid:e15e7cec-4355-43f0-9137-0b4608530eb4","Liquid crystalline thermosetting polymers as protective coatings for aerospace","Guerriero, G.L.","Benedictus, R. (promotor)","2012","Environmental regulations are driving the development of new aerospace coating systems, mainly to eliminate chromates and reduce volatile organic compound (VOC) emissions. Among the various potential options for new coating materials, liquid crystalline polymers (LCPs) are attractive due to their unique combination of mechanical properties and chemical resistance. Their use, however, has been limited mainly due to poor adhesion properties. Thermotropic liquid crystalline thermosets displayed the properties of traditional LCPs, while having the potential to overcome their disadvantages. The present research has been set to investigate the real potential of phenylethynyl terminated liquid crystalline thermosets (LCTs) for coating applications. The coatings were initially manufactured by melt-pressing the LCT resins onto aluminum substrates. This method was selected mainly due to its simplicity and minimal powder requirements. As a first step, the effects of the thermal curing and the molecular weight of the coating resins were investigated. Then, the influence of temperature and molecular orientation were examined. Subsequently, the adhesion and the environmental resistance of the LCT coatings were analyzed. Finally, the applicability of LCTs on aluminum and composite substrates using atmospheric plasma spraying (APS) was explored to address the industrial limitations of melt-pressing (on size, shape, and thermal resistance of the substrate). Being the first approach to the use of these LCTs as coatings, the present work has contributed to the knowledge and understanding of several aspects of the coating. The incorporation of the end-groups was found to promote the adhesion of the coating compared to the thermoplastic Vectra®, while it did not affect the environmental resistance. In addition, the new polymer chemistry allowed the polymers to be ground into a powder suitable for more versatile deposition methods like APS, expanding the range of applications. These LCTs, however, also present several disadvantages. An extra curing step at high temperature is required, during which, the properties are not significantly improved. In addition, the LCTs investigated here become more brittle after curing, which can be a disadvantage for tribological applications. Furthermore, mechanical properties such as the elastic modulus are not significantly higher than those of the thermoplastic LCP; and the formation of aggregate-aggregate interfaces constitute paths for crack propagation. Finally, untreated coating substrate interfaces constitute paths for environmental attack. The main characteristic of these coatings appeared to be their high chemical resistance and low permeability. These coatings are, therefore, applicable for the protection of surfaces exposed to aggressive liquids or flowing gases. Examples include heat exchangers, gearbox housings, undercarriage components, flooring, and hatches. Since these coatings constitute a passive protection, however, the development of a coating system that includes an active protection would be required to extend coating durability.","environmental resistance; atmospheric plasma spraying; liquid crystalline polymers; thermosets; coatings; mechanical properties","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Structural Integrity and Composites","","","",""
"uuid:89b628b0-a91a-4d32-b5dc-598b11d327cf","http://resolver.tudelft.nl/uuid:89b628b0-a91a-4d32-b5dc-598b11d327cf","Optimal design of variable-stiffness fiber-reinforced composites using cellular automata","Setoodeh, S.","Gurdal, Z. (promotor); Van Tooren, M.J.L. (promotor); Beukers, A. (promotor)","2005","Growing number of applications of composites materials in aerospace and naval structures along with advancements in manufacturing technologies demand continuous innovations in design of composite structures. In the traditional design of composite laminates, fiber orientation angles are constant for each layer and are usually limited to 0, 90, and 45 degrees. To fully benefit from the directional properties of composite laminates, such limitations have to be removed. The concept of variable-stiffness laminates allows the stiffness properties to vary spatially over the laminate. Through tailoring of fiber orientations and laminate thickness spatially in an optimal fashion, mechanical properties of a part can be improved. In this thesis, optimal design of variable-stiffness fiber-reinforced composite laminates was studied using an emerging numerical engineering optimization scheme based on cellular automata paradigm. Cellular Automata (CA) based design scheme uses local update rules for both field variables (displacements) and design variables (lay-up configuration and laminate density measure) in an iterative fashion to convergence to an optimal design. In the present work, the displacements are updated based on the principle of local equilibrium and the design variables are updated according to the optimality criteria for minimum compliance design. A closed form displacement update rule for constant thickness isotropic continua was derived, while for the general anisotropic continua with variable thickness a numeric update rule was used. Combined lay-up and topology design of variable-stiffness flat laminates was performed under the action of in-plane loads and bending loads. Optimality criteria based formulation was used to obtain local design rules for minimum compliance design subject to a volume constraint. It was shown that the design rule splits into a two-step application. In the first step an optimal lay-up configuration was computed and in the second step the density measure was obtained. The spatial lay-up design problem was formulated using both fiber angles and lamination parameters as design variables. A weighted average formulation was used to handle multiple load case designs. Numerical studies were conducted to investigate the performance of the proposed design methodology. It was shown that the optimal lay-up configuration is independent of the lattice density with more details emerging as the density is increased. Moreover, combined topology and lay-up designs were free of checkerboard patterns. The lay-up design problem was also solved using lamination parameters, instead of the fiber orientation angles. The use of lamination parameters has two key features; first the convexity of the minimization problem guarantees a global minimum; second for the in-plane and also for the bending problem it limits the number of design variables to four regardless of the actual number of layers thereby simplifying the optimization task. Moreover, it improves the convergence rate of the iterative design scheme as compared to using fiber angles as design variables, and provides a theoretically better design; however, manufacturability of the designs are not certain. Cases of general, balanced symmetric, and balanced symmetric with equal thickness layers were studied separately. The feasible domain for laminates with equal thickness layers was presented for an increasing number of layers. A restricted problem was proposed which maintains the convexity of the design space for laminates with equal thickness layers. A recursive formulation for computing fiber angles for this case was also presented. On the computational side of the effort, a parallel version of the present CA formulation was implemented on message passing multi-processor clusters. It was shown that a standard parallel implementation does not converge for an increased number of processors. Detailed analysis revealed that the convergence problem was due to a Jacobi iteration scheme, and a pure Gauss-Seidel through a pipeline implementation completely resolved the convergence problem. Timing results giving the speedup for the pipeline implementation were obtained for up to 260 processors.","cellular automata; compliance design; tow-placed laminates","en","doctoral thesis","TU Delft, Faculteit Luchtvaart- en Ruimtevaarttechniek","","","","","","","","Aerospace Engineering","","","","",""
"uuid:20484651-fd5d-49f2-9c56-355bc680f2b7","http://resolver.tudelft.nl/uuid:20484651-fd5d-49f2-9c56-355bc680f2b7","Static Aeroelastic Optimization of Composite Wings with Variable Stiffness Laminates","Dillinger, J.K.S.","Gürdal, Z. (promotor); Abdalla, M.M. (promotor)","2014","The application of composite material in load carrying structural components of an aircraft is rapidly gaining momentum. While part of the reason for this can certainly be attributed to an increasing confidence of designers in the new material as a result of growing experience, two other crucial points can be made. One, the continuous enhancements in the area of automated production technologies, which are an absolute necessity for ensuring consistent quality in a series production. Two, the progress in the development of computational methods to analyze and optimize composite structures in order to fully exploit their possible advantages over homogeneous materials. Nevertheless, it is still by virtue of challenges in their production as well as computational complexity, that full-fledged variable stiffness designs have not yet found their way in industrial large scale applications. Considering the complex path from the stiffness of a single laminate to the aeroelastic performance of an entire aircraft wing, it becomes clear that variable stiffness optimization is a non-trivial, laborious task. Not only does it require a large amount of design variables in order to achieve an adequate resolution, in addition the diverseness of responses impedes the problem definition. The research presented in this thesis aims at an advancement of the computational treatment, i.e. the development of a variable stiffness composite optimization framework, allowing for the consideration of static aeroelastic responses in the structural design of aircraft wings. Considering the different ways of optimizing composite structures, the strategy pursued in this thesis relates to a separation of the problem in three consecutive parts, the advantage being that each step can be handled with the most suitable optimization tools. The first part comprises an optimization based on laminate stiffnesses and is the main subject of this dissertation. It will be discussed in more detail below. The second part involves a stacking sequence optimization on the basis of the optimal stiffnesses derived in the first part. Part three deals with the optimal conversion of stacking sequences to fiber paths suitable for the chosen production technology. Parts two and three do not depend significantly on the physics of the problem. However, since it closely relates to the continuous optimization in part one, the stacking sequence optimization will also shortly be addressed. Part three is not dealt with in this thesis. The composite optimization framework consists of a successive convex subproblem iteration procedure, in which a gradient based optimizer consecutively solves a local approximation problem. Each response to be considered in the optimization, either as objective or as constraint, is approximated as a linear and/or reciprocal function of the laminate membrane and bending stiffness matrices A and D. Together with the laminate thicknesses h, they constitute the design variables in the optimization process. The distribution of design fields - each of which comprises its own set of A, D, h variables - within a structural entity like a wing skin, determines the variable stiffness resolution. Inside the optimization algorithm, stiffness matrices are parametrized by means of lamination parameters, resulting in a reduction in the amount of design variables on the one hand, and the constitution of a continuous, well-posed optimization problem on the other. The response sensitivities with respect to the design variables form an essential input in the assembly of response approximations. In this research, the finite element (FE) software Nastran is applied in order to generate sensitivities. Three major reasons account for this choice: one, the ability of specifying various types of responses, two, the time efficient implementation, and three, its prevalence in the aircraft industry. A Nastran FE model, suitable for the derivation of the required responses, is generated in a parametric model generation process. Aside from the structural FE representation, the model comprises a doublet lattice description for the computation of aeroelastic loads, and a mass model to incorporate non-structural masses like leading and trailing edge or fuel. Structural responses considered in the stiffness optimization are strength, buckling and mass. For strength, a failure criterion in lamination parameter space is adopted. Buckling is covered by a simply supported flat plate buckling model. Aside from the regular structural responses, the aeroelastic responses aileron effectiveness, divergence, and twist are also directly considered in the optimization process. While response values and sensitivities are an immediate result of Nastran, their approximations with respect to the design variables originate from a sensitivity convexification process, ensuring the approximation to incorporate as much reciprocal share as possible. The stiffness optimization fully relying upon the applied aeroelastic loads, a correction strategy by means of a higher order computational fluid dynamics (CFD) method is developed to enhance the doublet lattice aeroelastic loads. Eventually, the functionality of the stiffness optimization framework is verified by three applications, comprising different levels of complexity. Mostly wing skin weight serves as objective to be minimized, but also the maximization of aileron effectiveness for a prescribed weight is demonstrated. The possible advantages of unbalanced over balanced laminates are studied, as well as the influence of different sets of aeroelastic constraints on the achievable minimum wing skin weight. Finally, the modifications implied by an aero load correction are analyzed.","stiffness optimization; aeroelastic constraints; aileron effectiveness; divergence; lamination parameters; composites; variable stiffness","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Computational Mechanics Group","","","",""
"uuid:e49e4ead-22c4-4892-bbf5-5c3af46fc9f5","http://resolver.tudelft.nl/uuid:e49e4ead-22c4-4892-bbf5-5c3af46fc9f5","Objective Evaluation of Flight Simulator Motion Cueing Fidelity Through a Cybernetic Approach","Pool, D.M.","Mulder, M. (promotor)","2012","Compared to aircraft, flight simulators are severely limited in their motion envelopes. Presenting the true aircraft motion one-to-one on flight simulators is generally impossible and it is therefore common practice that these motion stimuli are only presented in reduced and attenuated form. Because of a limited understanding of human motion perception processes and how these affect the perceived realism of the multimodal stimuli pilots are subjected to during aircraft control (most notably, visual and physical motion stimuli), the definition of requirements for flight simulator motion cueing fidelity is a problem that researchers and legislators have struggled with for years. This thesis therefore describes and evaluates an objective method for the assessment of simulator cueing motion fidelity. The proposed method is centered around an analysis of the control dynamics adopted by pilots during manual control tasks, and how they use visual and motion stimuli in their selected control strategy, using multimodal pilot models. This approach thereby allows for the objective and quantitative evaluation of flight simulator motion fidelity, by explicitly considering how degraded motion cueing fidelity affects a simulator's ability to induce real-flight manual control behavior. This thesis describes a number of experiments in which pilot manual control behavior was measured using this approach in the Cessna Citation II laboratory aircraft and the SIMONA Research Simulator at Delft University of Technology. A comparison of the collected measurements clearly shows that variations in simulator motion cueing fidelity result in changes in pilot manual control behavior. With increased motion cueing fidelity, pilots are seen to rely significantly more on the presented motion stimuli, a control strategy that also typically results in increased manual control performance. Furthermore, these experiments also show that important behavioral parameters that characterize the weighing of visual and motion information by pilots also correspond best with those measured for in-flight pilot behavior when simulator motion cues are close to those of real flight.","flight simulation; motion cueing; pilot modeling; simulator fidelity","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Control & Simulation","","","",""
"uuid:008d10dc-3aa1-4b29-b445-579278543057","http://resolver.tudelft.nl/uuid:008d10dc-3aa1-4b29-b445-579278543057","Haptic gas pedal feedback for active car-following support","Mulder, M.","Mulder, J.A. (promotor); van der Helm, F.C.T. (promotor); Mulder, M. (promotor)","2007","The research presented in this dissertation focuses on supporting drivers in the longitudinal control of their vehicle during car-following. The goal of the research is the human-centred development of a haptic gas pedal interface that comfortably supports drivers in maintaining a safe separation with a leading vehicle during car-following. Two different approaches were found to be suitable for implementation as haptic information providers through the gas pedal. The first approach was to add a force to the gas pedal dynamics which would have to be related to the safe-field-of-travel ahead of the own vehicle and changes therein. The gas pedal dynamics, that is, the force/pedal-position relationship is not changed by this approach. The second approach was to change the stiffness of the gas pedal by adding a virtual stiffness to the inherent stiffness of the gas pedal. By doing so, the dynamics of the gas pedal are changed depending on the changes detected in the safe-field-of-travel. In both approaches, an electrical actuator provides the additional force or stiffness. The main hypothesis of this dissertation is the assumption that with the appropriate haptic feedback of longitudinal traffic information drivers will adopt a force-task in controlling the haptic gas pedal. Experimental verification leads to the conclusion that the stiffness feedback design with time-to-contact information scaled by time headway performs best in this respect.","haptic feedback; force; stiffness; gas pedal; car-following; time to contact; ttc; time headway; thw; driver; automotive; driving; driver support; human-centered","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:41232244-d9a2-4523-8f0f-810f1a1a4931","http://resolver.tudelft.nl/uuid:41232244-d9a2-4523-8f0f-810f1a1a4931","3D flow organization and dynamics in subsonic jets: Aeroacoustic source analysis by tomographic PIV","Violato, D.V.","Scarano, F.S. (promotor)","2013","To meet the increasingly stringent noise regulation, aircraft manufacturers are searching for solutions to jet noise. This, which constitutes a significant amount of the total noise emitted by civil aircrafts, is generated by the mixing processes between the exhaust flow leaving the engine and the atmosphere. A detailed understanding of such mixing process is of paramount importance to identify mechanisms responsible for noise production, i.e. the aeroacoustic source, and, ultimately, to develop noise control strategies. This thesis proposes an unprecedented experimental-based approach to visualize and measure the aeroacoustic sources in jet flows. Time-resolved tomographic particle image velocimetry (TR-TOMO PIV) is employed to obtain time-dependent three-dimensional (3D) measurements of the turbulent flow patterns, while the instantaneous aeroacoustic source is explored using Powell’s aeroacoustic analogy. TR-TOMO PIV experiments are conducted in a tailored jet facility. Measurements are performed both on jets issued through circular and 6-chevron nozzles, with the latter configuration that is nowadays used in jet engines to reduce acoustic emissions. The attention is placed upon the 3D organization and dynamics of flow transition, where coherent flow structures play a role in the generation of noise. The full 3D approach enables unambiguous descriptions of the vortex topology, while the temporal resolution allows addressing the growth and development of the coherent flow structures along with their mutual interaction. In the circular jet, the characteristic pulsatile motion of vortex ring shedding and pairing is accompanied by the growth of azimuthal instabilities and the formation of streamwise vortices leading to the breakdown of the vortex rings. In the chevron jet, instead, the axisymmetric ring-like coherence is replaced by streamwise flow structures whose decay is accompanied by the formation of C-shaped structures. The relation between coherent structures and the instantaneous acoustic source is investigated recalling Powell’s aeroacoustic analogy, with the acoustic source that is identified by the second time derivative of the Lamb vector. The spatio-temporal evolution of the source is mapped and is compared to that of the vortices, to detect flow events involved in the acoustic generation. In the circular jet, most pronounced source activity is observed during the vortex-ring breakdown, whereas, in the chevron configuration, is associated with the process of streamwise vortex decay and C structure formation. Performing unbiased acoustic predictions of the jet noise with TR-TOMO PIV measurements is a challenging task due to the constraints on the extent of the instantaneous measurement domain and on the required spatial and temporal resolutions. To meet this challenge, the thesis finally proposes a strategy to perform far-field acoustic predictions by direct evaluation of Powell’s analogy using TR-TOMO PIV data.","jet aeroacoustics; jet flows; tomographic PIV; coherent structures; 3D proper orthogonal decomposition; Powell's analogy","en","doctoral thesis","TU Delft","","","","","","","2013-04-25","Aerospace Engineering","Aerodynamics","","","",""
"uuid:bfe57561-523f-4e7e-8e28-e804a6f1625e","http://resolver.tudelft.nl/uuid:bfe57561-523f-4e7e-8e28-e804a6f1625e","Uncertainty quantification in particle image velocimetry and advances in time-resolved image and data analysis","Sciacchitano, A.","Scarano, F. (promotor)","2014","Particle Image Velocimetry (PIV) is a well-established technique for the measurement of the flow velocity in a two or three-dimensional domain. As in any other technique, PIV data is affected by measurement errors, defined as the difference between the measured velocity and its actual value, which is unknown. Aim of uncertainty quantification is estimating an interval that contains the (unknown) actual error magnitude with a certain probability. The present work introduces a novel methodology for the uncertainty quantification of PIV data. The method relies upon the concept of image matching: the PIV recordings are matched based on the measured velocity field. The positional disparity between paired particle images is then computed to retrieve the measurement uncertainty. Both the numerical assessment via Monte Carlo simulations and the experimental assessment show that the image matching approach allows estimating the measurement uncertainty in good agreement with the actual error value. Furthermore, advanced methodologies for time-resolved image and data analysis are investigated. Those methodologies include: the enhancement of the image quality via a temporal filter applied to the PIV images; a multi-frame processing algorithm (pyramid correlation) that improves precision and robustness of PIV measurements; a post processing approach based on the solution of the Navier-Stokes equations for estimating the velocity field in regions where no experimental data is available.","particle image velocimetry; uncertainty quantification; a-posteriori error estimation; time-resolved PIV; image analysis","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion (AWEP)","","","",""
"uuid:d3e4a54a-9052-4a2c-bf51-53c0c332fe40","http://resolver.tudelft.nl/uuid:d3e4a54a-9052-4a2c-bf51-53c0c332fe40","Ground Testing Investigation of Hypersonic Transition Phenomena for a Re-Entry Vehicle","Masutti, D.","Scarano, F. (promotor)","2013","","","en","doctoral thesis","Delft University of Technology","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:546afd8d-96ba-48e2-9481-f259fea481b1","http://resolver.tudelft.nl/uuid:546afd8d-96ba-48e2-9481-f259fea481b1","Automation in Architectural Photogrammetry: Line-Photogrammetry for the Reconstruction from Single and Multiple Images","Van den Heuvel, F.A.","Vosselman, M.G. (promotor)","2003","Architectural photogrammetry has been practised for more than a century for the documentation of cultural heritage. Nowadays, the emphasis is on the construction of computer models for virtual reality applications. Since the introduction of the computer, and later the digital camera, research in photogrammetry aims at automation. This thesis reports on research on automation in architectural photogrammetry for efficient reconstruction of detailed building models from one or more, possibly widely separated, digital close-range images. This research lies on the fringes of photogrammetry and computer vision. It treats topics frequently studied in computer vision in a photogrammetric way and offers new solutions. Examples cover interior orientation and reconstruction from a single mage, vanishing point detection, and the wide-baseline stereo problem. A semi-automatic approach is chosen that exploits knowledge of the object shape, such as planarity of facades, rectangular and repeating structures in the building, and shape symmetries. Automatically or manually extracted straight image line features are the main observations in the line-photogrammetric approaches presented in this thesis. Furthermore, the methods developed are characterised by the use of robust direct solutions for approximate value computation, followed by least-squares adjustment in which the knowledge of the shape of the building is processed together with the image line observations. This integral adjustment provides optimal estimates for the object model parameters and facilitates quality assessment.","photogrammetry; close-range; computer vision; architecture; camera calibration; image orientation; object reconstruction","en","doctoral thesis","NCG, Netherlands Geodetic Commission, Delft","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f3f51d76-f64e-43c0-ae03-94f39f8644c8","http://resolver.tudelft.nl/uuid:f3f51d76-f64e-43c0-ae03-94f39f8644c8","Improvements of thermoforming of thermoplastic composites using a collection of rubber particles as a soft mould half: Experiments and modelling","Antonelli, V.","Marissen, R. (promotor); Beukers, A. (promotor)","2014","Compression moulding is the ideal candidate for large series production of thermoplastic composite parts. Improvements in this production technique will make it more appealing for those markets that are reluctant to use composites because of their development costs. Unlike other composites processing systems, the compression moulding press is capable of producing fibre-reinforced plastic parts in significant volumes, with the accuracy, repeatability and speed to which, for example, the automotive industry has been accustomed in the stamping of metal parts. This thesis aims at a better understanding of the behaviour of the rubber mould during compression moulding of thermoplastics and consequently at the reduction of the development costs and improving the design of the rubber mould. The classical problems that need to be addressed when designing a rubber mould are the correct dimensions to accommodate the laminate and the positions of the details. The standard process, though, does not take into account the temperature changes in the mould during production and in particular the effect of the coefficient of thermal expansion of the rubber. In this thesis, an envisioned method to reduce this problem is to add a certain amount of aramide in the rubber mould, in order to restrict the expansion due to increased temperature. The second issue that has to be considered is the friction between the melted thermoplastic and the rubber mould. The use of lubricant is extremely effective, but can be used only in a prototyping phase, as the lubricant affects the mechanical properties of the thermoplastic composite. Proper modelling of the rubber forming process, considering the correct rubber parameters, allows identification of the problems that might occur during manufacturing. The way to eliminate those problems numerically, though, is computationally challenging as well as uncertain and time consuming. With those results in mind, an improved method was developed which substitutes the flexible rubber mould with a collection of rubber particles. The collection of rubber particles acts in a way similar to that of a fluid and has the advantage of filling the mould completely so that there is always contact between the rigid and the flexible mould. The new method allows the manufacturing of a wider range of products and allows the reduction of development costs related to the definition of the proper rubber mould shape. To be able to describe the collection of rubber particles as a homogeneus material, a series of tests has been designed for the determination of some of their physical parameters. The obtained material has a very variable stiffness, from a very low modulus when the particles are not compressed, to two orders of magnitude higher values when compaction is almost complete. Bulk and shear modulus are related to the Poisson’s ratio that does not vary much during the entire process, having a value always slightly below 0.5. This value is consistent with the fluid-like behavior in the beginning of the process and with the, almost incompressible, solid rubber block at the end of the process. Finally, the parameters found have been used to model the compression moulding process with a collection of rubber particles. Modeling is not strictly necessary because most of the existing problems in the conventional production method have been eliminated. However it might become useful when the limitations of the new production technique will be explored and in particular for those geometries that are not possible with the conventional method.","Thermoforming; Fibre Reinforced Thermoplastics; Material Characterisation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:148c69e4-50a3-4990-bc2b-0e76a2e16bdf","http://resolver.tudelft.nl/uuid:148c69e4-50a3-4990-bc2b-0e76a2e16bdf","Optimum lay-up design of variable stiffness composite structures","Van Campen, J.M.J.F.","Gürdal, Z. (promotor)","2011","Advancements in automated fibre-placement (AFP) technology make it possible to take laminate tailoring further than just stacking sequence optimisation; they enable the designer to vary the fibre orientation angle spatially within each ply. Spatial variation of fibre orientation angles results in a variable stiffness (VS) laminate. The work presented in this thesis constitutes a possible second step of a two-step design process for VS composite structures. The first step is to optimise a VS composite structure in terms of lamination parameters (LP), in the second step the LP design is converted into a lay-up design. The objective of this work was to investigate the available methods and to develop new methods to obtain the optimal VS lay-up design for a given LP design of a VS composite laminate that satisfies prescribed manufacturing constraints. The work in this thesis was divided into three parts to fulfil this objective: conversion of LPs into a lay-up design, design of blended composite lay-ups, and design of fibre-steered composite lay-ups. The reasoning behind this division was that, after a design in terms of LPs is converted into a design in terms of fibre angles, there are two possible ways to arrive at a variable stiffness laminate design: laminate blending or fibre steering. In this thesis a flexible computational tool set is presented that was developed to be used to convert a variable stiffness composite design, given in terms of lamination parameters, into an optimal variable stiffness laminate or blended composite lay-up design.","Automated Fibre Placement; Design Tailoring; Laminate Blending; Laminated Composites; Stacking Sequence Design; Variable Stiffness Composites","en","doctoral thesis","","","","","","","","2011-11-14","Aerospace Engineering","Aerospace Structures and Computational Mechanics","","","",""
"uuid:92e94609-ec37-43e5-ad01-3817756d30f6","http://resolver.tudelft.nl/uuid:92e94609-ec37-43e5-ad01-3817756d30f6","Establishing a sea bottom model by applying a multi-sensor acoustic remote sensing approach","Siemes, K.","Simons, D.G. (promotor); Hermand, J.P.O.F.G. (promotor)","2013","Detailed information about the oceanic environment is essential for many applications in the field of marine geology, marine biology, coastal engineering, and marine operations. Especially, knowledge of the properties of the sediment body is often required. Acoustic remote sensing techniques have become highly attractive for classifying the sea bottom and for mapping the sediment properties, due to their high coverage capabilities and low costs compared to common sampling methods. In the last decades, a number of different acoustic devices and related techniques for analyzing their signals have evolved. Each sensor has its specific application due to limitations in the frequency range and resolution. In practice, often a single acoustic tool is chosen based on the current application, supported by other non-acoustic data where required. However, different acoustic remote sensing techniques can supplement each other, as shown in this thesis. Even more, a combination of complementary approaches can contribute to the proper understanding of sound propagation, which is essential when using sound for environmental classification purposes. This includes the knowledge of the relation between acoustics and sediment properties, the focus of this thesis. Providing a detailed three dimensional picture of the sea bottom sediments that allows for gaining maximum insight into this relation is aimed at. Chapters 4 and 5 are adapted from published work, with permission: DOI:10.1121/1.3569718 (link: http://asadl.org/jasa/resource/1/jasman/v129/i5/p2878_s1) and DOI:10.1109/JOE.2010.2066711 (link: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=5618582&queryText%3Dsiemes) In reference to IEEE copyrighted material which is used with permission in this thesis, the IEEE does not endorse any of the TU Delft's products or services.","acoustic remote sensing; marine sediment; sub-seafloor; environmental characterization; single-beam echosounder; multibeam echosounder; seismic profiling; chirp; geoacoustic inversion; phenomenological approach; model-based approach; density; compressional sound speed; acoustic attenuation; sediment samples; fine-grained sediments; gas","en","doctoral thesis","Uitgeverij BOXPress","","","","","","","2015-12-31","Aerospace Engineering","Control and Operations","","","",""
"uuid:0aca44b8-0979-4ad2-b3f5-f59df411b596","http://resolver.tudelft.nl/uuid:0aca44b8-0979-4ad2-b3f5-f59df411b596","Investigations on the supersonic flow around bodies","Zandbergen, P.J.","Van Spiegel, E. (promotor)","1962","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2b272737-2761-4833-a2bb-ad722bc688fb","http://resolver.tudelft.nl/uuid:2b272737-2761-4833-a2bb-ad722bc688fb","Similarity laws for turbulent boundary layers with suction or injection","Tennekes, H.","Steketee, J.A. (promotor)","1964","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:22554e85-9506-4410-9fb3-9ad6af4b2c8d","http://resolver.tudelft.nl/uuid:22554e85-9506-4410-9fb3-9ad6af4b2c8d","Investigation of Practical Flight Control Systems for Small Aircraft","Falkena, W.","Mulder, J.A. (promotor)","2012","Personal air transportation utilizing small aircraft is a market that is expected to grow significantly in the near future. However, seventy times more accidents occur in this segment as compared with the commercial aviation sector. The majority of these accidents is related to handling and control problems. In commercial aviation, Fly-By-Wire (FBW) technology is used to prevent these types of accidents. Instead of downscaling advanced and high-cost FBW platforms, a low-cost solution should be considered for the general aviation market. In the European project “Small Aircraft Future Avionics Architecture”, a FBW platform is developed specifically for small aircraft. In this environment, Flight Control Law (FCL) designs are needed that have robustness against model uncertainties, sensor bias, sensor noise and time delays, while being fast and accurate enough to accommodate the relatively agile dynamics of a small aircraft. FCL designs that meet these requirements are called practical FCL designs in this thesis. Based on a dynamic model of a Diamond DA 42 and a description of the dynamic properties of the FBW platform, two different FCL designs are synthesized and analyzed in this thesis. The first design uses classical control theory and the second design uses a newly developed nonlinear design method, based on backstepping, singular perturbation theory and approximate dynamic inversion. This latter method, called Sensor-Based Backstepping (SBB), uses no dynamic model information and relies solely on measurements. Both FCL designs are compared on sensitivity to parametric uncertainty, sensor noise, disturbances, time delays, handling qualities, design effort, certifiably and the option to add flight envelope protection. In the scope of this thesis, SBB is selected as the preferred FCL design. This method produces good aircraft responses without knowing the exact dynamic behavior of the aircraft during FCL synthesis, as long as the system is minimum phase, controllable and sufficiently time-scale separated.","General Aviation; Fly-by-Wire; Flight Control Law Design; Backstepping; Sensor-based backstepping; Incremental backstepping; Flight Envelope Protection","en","doctoral thesis","W. Falkena","","","","","","","2012-12-17","Aerospace Engineering","Control and Operations","","","",""
"uuid:33b532d7-a999-4cc7-a96f-7aa87f092577","http://resolver.tudelft.nl/uuid:33b532d7-a999-4cc7-a96f-7aa87f092577","On the Necessary Degrees of Freedom for Helicopter and Wind Turbine Low-Frequency Mode Modeling","Pavel, M.D.","van Holten, Th. (promotor)","2001","","Necessary Degrees of Freedom; Helicopters; Wind Turbines; Flight Mechanics; Structural Modeling","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6918a4d0-2b75-44e6-bf33-2822d7c2d264","http://resolver.tudelft.nl/uuid:6918a4d0-2b75-44e6-bf33-2822d7c2d264","Active aerodynamic load control on wind turbines: Aeroservoelastic modeling and wind tunnel","Barlas, A.","Van Kuik, G.A.M. (promotor)","2011","This thesis investigates particular concepts and technologies that can alleviate fatigue loads on wind turbines by using distributed active aerodynamic devices on the blades, a concept briefly referred to as `smart blades'. Firstly, published research work on smart control devices is reviewed, and the pros and cons for the application on wind turbines is discussed. Then an introduction to the quantification of unsteady loads on the blades of a representative 5MW reference wind turbine is given. Based on this, certain requirements for the load control concepts to alleviate the fatigue loads are presented. Moreover, an overview of possible smart rotor concepts with a view towards application to wind turbines is provided. The choice is made for active load control by trailing edge flaps. The theoretical background for the unsteady aerodynamics modeling of airfoils with trailing edge flaps, is included, focusing on wind turbine blades. Moreover, results of 2D aerodynamic load control with aps are shown. Experimental wind tunnel work on a aeroelastically scaled non-rotating blade, where feedback control using piezoelectric-material based flexible flaps is also performed. A developed full wind turbine aeroservoelastic code is presented, capable of simulating rotors with span-wise distributed trailing edge flaps and various sensor and control capabilities. Furthermore, novel wind tunnel experimental work on a scaled rotor equipped with flexible flaps is shown, providing measured load alleviation results. Numerical predictions, correlated with the scaled rotor experiment, using the developed aeroservoelastic tool are shown, giving a reasonable correspondence. Various numerical predictions with the use of the aeroservoelastic model for the case of a representative 5MW wind turbine are presented. Aeroelastic behaviour of smart wind turbine rotors and design of various complexity controllers for active flaps are analysed. The fatigue load can be lowered up to 27%. Conclusions from this research work are finally drawn, with a view towards future work in the field.","smart rotor; active flaps; wind turbine; aeroelasticity; aeroservoelasticity","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","","",""
"uuid:25ffb34c-adb4-4e17-a294-6b707ddc0e9b","http://resolver.tudelft.nl/uuid:25ffb34c-adb4-4e17-a294-6b707ddc0e9b","Impact on ceramic faced armour","Den Reijer, P.C.","Arbocz, J. (promotor)","1991","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:73a4025d-c519-4e3a-b1cd-c1c8aa0fdfeb","http://resolver.tudelft.nl/uuid:73a4025d-c519-4e3a-b1cd-c1c8aa0fdfeb","Predicting the Structural Performance of Composite Structures Under Cyclic Loading","Kassapoglou, C.","Gurdal, Z. (promotor)","2012","The increased use of advanced composite materials on primary aircraft structure has brought back to the forefront the question of how such structures perform under repeated loading. In particular, when damage or other stress risers are present, tests have shown that the load to cause failure after a given number of cycles is a decreasing function of these cycles. This is a result of damage that was already present in the structure or was created during cyclic loading. In composites, multiple types of damage may be present in the structure at the same time such as matrix cracks, fiber kinks, delaminations, broken fibers, etc. These types of damage may interact and transition from one type to another and are, ultimately, responsible for structural failure. In trying to predict the number of cycles to failure of a composite structure it is, therefore, necessary to understand how damage is created, how it evolves and how different types of damage may interact or coalesce. A first step in that direction, using what is one of the simplest models that can be used, is the subject of this thesis. The number of cycles to failure is related to the residual strength of the structure for constant amplitude loading. A simple first-order model is postulated that determines the residual strength at any point during the fatigue life as a function of the residual strength at any earlier point in time. For constant amplitude loading, the resulting expression relates the maximum applied load, the number of cycles, the cycles to failure corresponding to the applied load, and the residual strength at the beginning of a test, to the residual strength at the end of the test. With the residual strength known as a function of cycles, a cycle-by-cycle probability of failure is introduced. It is shown that, if the static (or residual) strength follows a two-parameter Weibull distribution, the cycle-by- cycle probability of failure is constant and independent of the number of cycles. For the case of constant cycle-by-cycle probability of failure, the number of cycles to failure is determined as the value that maximizes the likelihood of failure. The resulting expression is in terms of the cycle-by-cycle probability of failure. If the residual strength distribution is known, the cycles to failure can be expressed in terms of parameters of this distribution. Simple closed-form expressions are obtained for two-parameter Weibull distributions. For other types of distributions (normal or lognormal for example) no closed form expressions were found. The effect of R ratio is incorporated using a simple proportional relation that accounts for the load excursion being different from that for R=0. The predictions of this approach for constant amplitude loading situations were compared to test results in the literature for a wide variety of laminates, materials, and loading conditions. While in some cases the agreement of test results with predictions was excellent, in others the discrepancy clearly suggested that the analytical model must be improved. The analytical model was also used to construct Goodman diagrams and determine omission levels for tests. Comparison of analytically predicted Goodman diagrams to test results showed good agreement in the tension-dominated portion of the diagram but some disagreement in the compression-dominated portion. This is attributed to the simplicity of the model which does not accurately capture interaction of failure modes when both tension and compression loads are present. The omission level is the load level below which no damage is created, no growth of existing damage is observed, and no failure occurs for a prescribed number of cycles. This allows shortening of test programs by eliminating cycles with loads below the omission level. Comparisons of predictions to test results showed very good agreement over a wide variety of tests, materials, R ratios, notches, and layups. The model, in its simplest form, was then extended to spectrum loading cases. This was done by creating an equivalence between different load levels and applied cycles by matching the residual strength at the end of each load level. For this approach to work, the failure mode and damage type dominating the fatigue life must be the same for the two (or more) load segments of interest. This then allows a single quantity, the residual strength, to accurately describe the damage state. Simple closed form expressions were obtained for the number of cycles or load segments to failure under spectrum loading. Comparisons with test results showed good agreement for tension-dominated spectra but major discrepancies for compression-dominated spectra again pointing to the need for improving the model to account for interaction of multiple failure modes and types of damage. The main reason for the discrepancies between test results and analytical predictions was the constant cycle-by-cycle probability of failure that resulted from the original assumptions in the model. If there is one dominant failure mode the cycle-by-cycle probability of failure is constant. However, when more than one types of damage or failure modes are present, their interaction and the resulting load redistribution in the structure changes the cycle-by-cycle probability of failure. The model was, therefore, modified by assuming that the probability of failure is constant over a limited number of cycles until another failure mode or damage type occurs and changes the residual strength and the cycle-by-cycle probability of failure. This can become quite complex even for the apparently simple case of a uni-directional laminate under tension where, during cyclic loading, weak fibers fail and their load is redistributed to adjacent fibers. The main difficulty is then in creating an analytical model that can accurately determine stresses throughout the structure as damage evolves and, on the basis of these stresses, predict the residual strength. The improved model was applied to two cases, a uni-directional laminate and a cross-ply laminate of the form [0m/90n]s under tension-tension fatigue. For the uni-directional laminate, the improved predictions for cycles to failure were in excellent agreement with test results. For the cross-ply laminate, the accuracy of the predictions ranged from excellent to poor depending on the ratio of the thickness of internal 90o plies to that of the surrounding 0o plies. The main issue in this case is that the analytical model developed for predicting stresses around matrix cracks and the associated load redistribution in the laminate are not very accurate as the crack density increases beyond a certain point. More accurate analytical modeling of this situation is expected to improve the predictions for cycles to failure. The analysis method proposed here is still in its infancy. In its simplest form, it is shown to work well in many cases but not well in others. What is important is that a framework for performing fatigue analysis of composites is presented, which relies on the residual strength and how that varies with cycles as damage is created and evolves. Essentially, what is proposed here is a wear-out model. Wear-out models have been proposed before. The main difference and potential improvement here is that there is no need for curve fitting test data or experimentally determined fatigue parameters. The equations governing the model are determined analytically and, in some cases, in closed form. While the model needs further improvements mainly in how the creation of different types of damage is predicted and how their interaction and evolution is accounted for, it is very promising because it provides a general and purely analytical methodology to predict cycles to failure under constant amplitude or spectrum loading.","fatigue analysis; composite materials; damage; probability of failure; residual strength","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Computational Mechanics","","","",""
"uuid:da36bee8-c128-49ea-812b-8976fa055426","http://resolver.tudelft.nl/uuid:da36bee8-c128-49ea-812b-8976fa055426","Ornicopter Multidisciplinary Analyses and Conceptual Design","Wan, J.","Van Tooren, M. (promotor)","2014","The tail rotor of conventional helicopters has always been considered a necessary 'evil'. It is necessary to counteract the reaction torque of the engine and to control the helicopter in yaw but it consumes substantial power, has only marginal control authority under unfavourable wind conditions, and it is noisy, vulnerable and dangerous. A solution to all these problems would be a helicopter concept that eliminates the need for a tail rotor. The so-called 'Ornicopter', a helicopter with flapping blades, is such a concept. The mechanism of the Ornicopter is inspired by bird flight. When birds flap their wings they are able to generate both a lifting force and a propelling force from this single movement. Instead of propelling a helicopter blade by spinning it around and deriving lift from this rotating movement, as is done in conventional helicopter configurations, the Ornicopter flaps its blades like a bird and derives both lift and a propulsive force from this movement. In this case the blades propel themselves and there is no longer a need for a direct torque supplied by the engine to rotate the blades. The Ornicopter's rotor, therefore, will not cause a reaction torque on the fuselage, which makes the tail rotor's anti-torque function redundant. The goal of the present thesis is to develop a thorough understanding of the Ornicopter concept and its feasibility throughout a realistic flight envelope. The first part presents the analysis of the Ornicopter's main characteristics regarding performance, stability, controllability, handling qualities, as well as an exploratory vibratory analysis. In the second part a preliminary design and sizing thereof are presented based on the conclusions obtained in the first part. The basis for the Ornicopter's study is an analytically-derived flight mechanics model. The model is based on the blade element theory (BET) and considers 6 rigid body degrees of freedom (DoF), 3 DoF blade flapping dynamics and 3 DoF Pitt-Peters inflow dynamics. Previous mathematical models developed as a proof of the Ornicopter concept have concentrated mainly on hovering flight. The model developed in this thesis is capable of representing the Ornicopter's dynamics well within its entire operational flight envelope. As a benchmark for the Ornicopter's specifications, the Bolkow Bo-105 helicopter is used. The Bo-105 helicopter is a light twin-engine, multi-purpose helicopter developed in Germany in the 1970s. For the initial values of the design parameters of the Ornicopter (such as rotor radius, blade loading, rotor tip velocity, vertical fin size) the Bo-105 helicopter design is used. A 2X2 anti-symmetric rotor flapping configuration (with two opposite blades flapping in the same direction) is used for the Ornicopter in order to eliminate the necessity for a tail rotor. Using these design parameters it is demonstrated that the Ornicopter rotor can generate enough propulsive torque to rotate the blades with modest flapping amplitudes (maximum less than 9 deg). The present thesis demonstrates that, compared to the Bo-105 helicopter, the Ornicopter concept suffers from higher required power, a smaller flight envelope (mainly due to the larger rotor stall area) and lower yaw stability. All these drawbacks are attributed to the large rotor blade angle of attack variation introduced by the forced flapping mechanism and the absence of a tail rotor. In the second part of this thesis, the Ornicopter concept is optimized for performance. Keeping the performance specifications of the Bo-105 as the objectives, the design values (blade radius, blade loading etc) are turned to fit the Ornicopter concept and no longer use the Bo-105 design values. The design optimization is formulated through minimization of the required power, while satisfying the stall area requirement. The thesis proves that the optimal design for the Ornicopter as compared to the Bo-105 benchmark is characterized by a lower blade loading, increased rotor tip velocity and larger vertical fin size. This optimal design results in an enlarged flight envelope due to the reduced rotor stall area and improved yaw stability in forward flight. Nevertheless, despite these improvements in the Ornicopter's flight envelope, there is a slight increase in required power when compared with the Bo-105 specification (approximately 5% at 150 knots). To compensate for the higher profile power needed for the Ornicopter's optimal design, a larger rotor radius is required in order to reduce the induced power and keep the increase in the total required power to a minimum. This thesis may be considered as a first step in rationalizing the expectations regarding the Ornicopter's tailless helicopter design. The thesis proved that this new concept shows a slightly poorer performance than that of conventional helicopters regarding power consumption in forward flight and service ceiling. This is disappointing since one of the assumptions was that the elimination of the tail rotor would also eliminate the power consumption associated with a tail rotor. Further analyses of the Ornicopter's performance (such as endurance, payloads, climbing performance, and environmental performance related to safety and noise), costs or maintenance should be performed for a comprehensive understanding of the advantages and disadvantages of this helicopter concept.","tailless helicopter; conceptual design; active flapping","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration & Operations","","","",""
"uuid:1a68ee94-3d55-44b9-9d8b-25fa44e96922","http://resolver.tudelft.nl/uuid:1a68ee94-3d55-44b9-9d8b-25fa44e96922","Precise Relative Positioning of Formation Flying Spacecraft using GPS","Kroes, R.","Ambrosius, B.A.C. (promotor)","2006","Spacecraft formation flying is considered as a key technology for advanced space missions. Compared to large individual spacecraft, the distribution of sensor systems amongst multiple platforms offers improved flexibility, shorter times to mission, and the prospect of being more cost effective. Besides these advantages, satellite formations in low Earth orbit provide advanced science opportunities, such as measuring small scale variations in the Earth's gravity field or higher resolution imagery and interferometry. One of the fundamental aspects of spacecraft formation flying missions is the precise determination of the relative state (position and velocity) between the satellite vehicles within the formation. GPS receivers are often considered as the primary instruments for this task in future spacecraft formation flying missions. As is commonly known, precise relative positioning between GPS receivers in geodetic networks is exercised on a routine basis. Furthermore, GPS receivers are already frequently used onboard satellites to perform all kinds of navigational tasks. Moreover they are suitable for real-time applications and provide measurements with a 3-dimensional nature. This dissertation presents a thorough overview of various GPS based strategies for precise relative spacecraft positioning, which have all been tested using real-world GPS data from the GRACE satellite mission. In addition, a substantial part of this work is also dedicated to quality aspects of the GPS observation data used as well as precise GPS based orbit determination strategies of single spacecraft. This dissertation is therefore recommended to all readers interested in GPS for spacecraft positioning applications.","precise orbit determination; relative positioning; spacecraft formation flying","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:33f5538b-280d-435f-87a3-6295f942d6b3","http://resolver.tudelft.nl/uuid:33f5538b-280d-435f-87a3-6295f942d6b3","Irradiation-induced degradation of amorphous silicon solar cells in space","Klaver, A.","Beenakker, C.I.M. (promotor)","2007","Solar cells are the prime power supply for satellites in space. Space is, however, a hostile environment for electronic devices, such as solar cells: in space the devices are subjected to large temperature cycles, atomic oxygen, space dust, meteorites, and high-energy charged-particle irradiation. In this thesis we present the development of a model with which the EOL-performance of hydrogenated amorphous silicon, solar cells can be predicted for a high-radiation space mission. For this development we have performed light-soaking, electron-beam, and proton-beam irradiation experiments on Hydrogenated amorphous silicon, layers and solar cells in order to study the degradation cell performance under these conditions. Furthermore, we present a procedure for the simulation of solar-cell performance degradation and this method has been applied to our measurement results to study some aspects of the degradation in more detail.","hydrogenated amorphous silicon; degradation; radiation; solar cells","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:83bfe59a-5cf3-4127-9f77-9d48abd97da1","http://resolver.tudelft.nl/uuid:83bfe59a-5cf3-4127-9f77-9d48abd97da1","Isogeometric analysis for thin-walled composite structures","Guo, Y.","Bisagni, C. (promotor); Ruess, M. (promotor)","2016","The conceptual ideas behind isogeometric analysis (IGA) are aimed at unifying computer aided design (CAD) and finite element analysis (FEA). Isogeometric analysis employs the non-uniform rational B-spline functions (NURBS) used for the geometric description of a structure to approximate its physical response in an isoparametric sense. Due to the tensor product property of multi-variate NURBS, it is difficult to represent complex topological shapes with a single NURBS patch. Multiple, often non-conforming patches are needed to tackle increasing complexity of the geometry. To further facilitate the modeling of complex shapes and geometric features trimming technology is widely used in CAD software, however, the trimmed domain is only visually unseen and the trimming features can not be utilized directly for the analysis. To overcome these difficulties, extra efforts are needed to make isogeometric methods adapted to engineering related cases. Thin-walled structures, such as plates and shells, excel in optimal load-carrying behavior and are of major importance in the design of aerospace components and the automotive engineering. Isogeometric analysis is an ideal candidate for the modeling and simulation of shell structures, especially for rotation-free Kirchhoff-Love type shells, which profit from the exact description of the geometry and from the higher continuity properties of NURBS. Furthermore, it favorably supports continuity requirements for flexible through-the-thickness design of laminate composites. Laminated composite materials are increasingly used in the aerospace industry this asks for reliable and computationally efficient lamina theories. The classical lamination theory belongs to the class of equivalent-single-layer methods (ESL), it is computationally efficient but often fails to capture the 3D stress state accurately. The demand for an accurate 3D stress state within laminates is mainly driven by the need to identify and to evaluate potential damage of lamina structures. While a full 3D layerwise (LW) model is computationally expensive, a combined approach considering both concepts, ESL and LW, seems to be a natural choice to tackle the computational costs of increasing model size and model complexity. In this thesis, a layerwise method for laminated composite structures is proposed in the framework of isogeometric analysis. A highly accurate prediction of the state of stress for thick and moderately thick laminate composite shells including transverse normal and shear stresses is demonstrated. The layerwise theory is successfully extended to linear buckling analysis of delaminated composites where a contact formulation is added to eliminate physically inadmissible buckling states which may result from overlapping plies. Furthermore, a Nitsche type formulation is introduced to enforce both weakly, essential boundary conditions and multi-patch coupling constraints for trimmed and non-conforming isogeometric rotation-free Kirchhoff-Love shell patches. The proposed formulation is variationally consistent and excels in a high level of stability and accuracy. A built-in stabilization, used to ensure coercivity of the formulation, prevents ill-conditioning of the physical problem. The inherent trimming problem is tackled with a fictitious domain extension for the trimming domain following the principles of the finite cell method to facilitate the workflow for geometrically complex structures in engineering practice. Computational efficiency is significantly increased with a blended coupling, taking continuum-like shell elements and thin shells elements, according to the theory of Kirchhoff-Love, into account. The blended approach provides access to the full 3D state of stress within selected subdomains while preserving the computational efficiency of the overall analysis.","isogeometric; composite laminates; layerwise; thin-walled structures; multi-patch; finite cell method","en","doctoral thesis","","","","","","","","2016-03-20","Aerospace Engineering","Aerospace Structures and Computational Mechanics","","","",""
"uuid:0af8c4fa-5e6f-4328-b933-0e6af240ea99","http://resolver.tudelft.nl/uuid:0af8c4fa-5e6f-4328-b933-0e6af240ea99","Ecological Automation Design, Extending Work Domain Analysis","Amelink, M.H.J.","Mulder, J.A. (promotor); Mulder, M. (promotor)","2010","In high–risk domains like aviation, medicine and nuclear power plant control, automation has enabled new capabilities, increased the economy of operation and has greatly contributed to safety. However, automation increases the number of couplings in a system, which can inadvertently lead to more complexity from the perspective of the operator. The automation of a system transforms the work domain of the human operator, and his role changes from controlling the core processes to managing the automated processes. The complexity of the automation and the lack of proper support can make the control task’s overall difficulty larger than it needs to be, restricting safety, productivity, and efficiency. To address and limit the automation introduced complexity in the operator’s work domain, and to find representations to support him, the ecological approach to automation design was taken. The ecological approach focuses on the relationship between the human operator and his work domain including the system he is controlling. The main research goals were to find how the ecological approach could be used to help limit the automation introduced complexity, and how the ecological approach could be used to support the human operator in controlling automated processes. The formulation of Ecological Automation Design (EAD) was based on the Ecological Interface Design (EID) paradigm. One of the main underlying questions asked about the interface between the work domain and the human operator is: “how to represent work domain complexity?"". The inter face design paradigm was transformed into an automation design paradigm by first separating the automation component from the work domain and asking the same underlying question about the interfaces between the work domain, the human operator, and the automation. Then, the conceptual shared domain representation was defined to visualize that the apparent complexity of the system could be reduced when both the human operator and the automation view the same representation of constraints that the work domain imposes on control. As part of the ecological approach, Work Domain Analysis (WDA) was used to analyze and represent the constraints in a work domain. However, WDA is not yet fully developed and suffers from some methodological and conceptual issues. The research therefore, focused on the further development and extension of WDA to include the representation of automated processes. Four case studies were conducted, and each case study generated new insights into the application of and extension of WDA. In the first case study, EID was applied to the design of the Energy Augmented Tunnel In the Sky display. This display was designed to aid a pilot to fly the approach to landing by presenting energy management information. The WDA revealed the significance of the energy coupling between vertical flight path and speed control as an intermediate control goal. Based on the analysis, a creative design process resulted in a novel display that has the energy representations fully, and graphically integrated in the tunnel in the sky display. A preliminary evaluation indicated that the additional energy management information shown in relation to the control actions and control goals helped pilots to fly the approaches. The display is not expected to give a performance increase but to change the way in which pilots control the throttle and elevator to fly approaches. The second case study was the analysis of the already existing Total Energy Control System (TECS). TECS is an unconventional automated flight control system that was based on the same energy management constraints as that were represented in the energy augmented display of the first case study. The design of TECS was mapped onto the abstraction hierarchy to represent the energy management principles as part of the whole automated system. The analysis and useful representation of TECS using the abstraction hierarchy was not straightforward. It involved a search for the interpretation of the levels of the abstraction hierarchy and the use of the means–ends relationship in conjunction with the aggregation relationship. The resulting WDA showed that the abstraction hierarchy could be used to map out the reasons for TECS’s design features. Many constraints were represented in the same space, which cluttered the energy management principles. The focus was put on the energy management principles through selective aggregation of the represented functions, but other design principles were omitted. To provide a complete representation of the system but without the clutter, the levels of control sophistication were introduced to represented nested control problems separately. At each level of control sophistication the abstraction hierarchy was applied, resulting in the Abstraction–Sophistication Analysis (ASA). In the third case study, the ASA framework was used to guide the design of SmartUAV. SmartUAV is a newly designed mini–UAV system that is capable of controlling multiple small UAVs from a laptop computer. By designing and developing SmartUAV we gained hands–on experience with how WDA, and especially the ASA, helped to keep track of and deal with the automation introduced constraints in the design phase. The levels of control sophistication were used from the beginning to separate the different control problems in the domain. They ranged from flying the platform to the achievement of missions. Starting at the lowest level of control sophistication, each higher level allowed the designer to include a larger part of the complete work domain incrementally, and to focus on more sophisticated control of the UAV. Furthermore, the ASA supported the visualization of how automation transformed the work domain, thus how automated functionalities that were created at lower levels of control sophistication affected the (automated) functions at higher levels of control sophistication. This study showed that the ASA could span a much larger problem space than the original WDA through the nesting of abstraction hierarchies. The ASA provided a systematic way to address the abstraction of the control problems (levels of control sophistication) and the abstraction of functions per control problem (abstraction hierarchy). The fourth case study dealt with the analysis of a subset of a well structured domain that lacks automation; sailboat racing. This study generated a clearer view on the nested structure that is inherent in a work domain, as apposed to the nested structure of the automation as found in TECS and SmartUAV. The nested structure inherent to this work domain was found to be the result of how sailboat racing has evolved over time, based on the capabilities of equipment, human performance and the racing rules. Due to the lack of automation, it became clear that human performance is in fact part of the work domain, in contrast to the original formulations of WDA. The crew’s performance formed the basis for achieving the more sophisticated control of boat speed, tactics and strategy, thus was essential in the analysis. It was shown that the performance of the human crew could be represented in the ASA at a level of control sophistication, while this could not be supported in a non–nested WDA based on a single abstraction hierarchy. The four case studies exemplified WDA and led to its extension with a structure to explicitly nest abstraction hierarchies that map out different control problems: the ASA. Through generating the analyses, extensive modeling experience with the abstraction hierarchy was obtained, reducing its ambiguity and potential methodological and conceptual problems. We found that the abstraction hierarchy could be used to model the structure of the knowledge about a work domain but could not model the knowledge itself. Therefore, the abstraction hierarchy is a framework for structuring knowledge, linking different representations of a control problem, and explaining the reasons for design features of a system. The abstraction hierarchy addressed the abstraction of elements belonging to a control problem, and the levels of control sophistication addressed the abstraction of the control problem itself. Representations in the ASA framework ranged from physical at the lower levels of control sophistication to non–physical at the higher levels of control sophistication. It allowed the structuring of, for example: the sailboat racing rules at the higher levels, and the law of conservation of energy at the lower levels. Although the application of the ASA did not inherently reduce the complexity of the design of SmartUAV, it enabled us to better understand the elements of the work domain that contribute to complexity of the system prior to and during its design. The extension of work domain analysis with the levels of control sophistication has led to a richer representation of the studied work domains than a single abstraction hierarchy or the abstraction–decomposition space.","cognitive systems engineering; human factors; work domain analysis; abstraction hierarchy; ecological interface design","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:32a7ae08-96fe-4f0e-baf3-1af379580708","http://resolver.tudelft.nl/uuid:32a7ae08-96fe-4f0e-baf3-1af379580708","Micromechanical modeling and simulations of transformation-induced plasticity in multiphase carbon steels","Tjahjanto, D.D.","Van der Zwaag, S. (promotor); Turteltaub, S.R. (promotor)","2008","","martensitic transformation; crystal plasticity; transformation-induced plasticity; thermo-mechanical framework; consistent stress-update algorithm; finite element method; homogenization scheme; microstructural properties","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3ac51a24-cfc1-42cf-b057-cbc882db5e92","http://resolver.tudelft.nl/uuid:3ac51a24-cfc1-42cf-b057-cbc882db5e92","Gas-liquid flows in a two-fluid formalism: Modelling and validation of closure relations","Oey, R.S.","Van den Akker, H.E.A. (promotor); Mudde, R.F. (promotor)","2005","","two-fluid formulation; closure modelling; gas-liquid flows; numerical simulations; finite-volume method","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:700dba13-23cb-44b3-93f8-9c71ff00a8f3","http://resolver.tudelft.nl/uuid:700dba13-23cb-44b3-93f8-9c71ff00a8f3","Underwater detection, classification and localisation: Improving the capabilities of towed sonar arrays","Colin, M.E.G.D.","Simons, D.G. (promotor); Blacquiere, G. (promotor)","2011","The end of the Cold War and the collapse of the Warsaw pact have resulted in a change of operational theatre for the naval forces of the North Atlantic Treaty Organisation (NATO). In particular, the focus of Anti Submarine Warfare forces has shifted from tracking Soviet nuclear ballistic missile submarine in the deep waters of the Atlantic ocean to hunting smaller and quieter Diesel electric submarines in coastal water. In most scenarios, towed array sonars are the best sensor to detect, classify and localise submarines. The long passive towed array sonars used during the Cold war are more difficult to use in coastal waters and are being replaced by most Navies by Low Frequency Active Sonars (LFAS) using a towed source and shorter towed receiving array. These shorter towed arrays can be used in both active and passive modes. In passive mode, their reduced size offer limited performance compared to their longer equivalent. In active mode, they can detect submarines at long ranges in shallow waters but are plagued by false alarms caused by echoes from features of the seafloor. This thesis deals with algorithms improving Detection, Classification and Localisation for towed sonar arrays, with a specific focus on LFAS sonars. In Chapter 2, we derive, analyse and apply to measured data a method for improving detection performance with short passive towed arrays. An important issue in detection of quiet acoustic source with short towed arrays is the improvement in signal-to-noise ratio (SNR) and bearing resolution for targets emitting low frequency signals. One of the techniques believed to improve these characteristics is Synthetic Aperture Sonar (SAS). The method is based on the artificial enlargement of a sonar array by coherently integrating acoustic snapshots at different antenna positions. We first derive theoretical measures of performance of passive SAS and report on its application in combination with other signal-processing algorithms. Its theoretical performance is compared with that of the frequently used incoherent integration. The used passive SAS algorithm is the method known as Extended Towed Array Measurement (ETAM) or the overlap correlator. It is based on the correlation of data snapshots on overlapping hydrophones. Correlation is a key issue in this method and since it is affected by noisy targets, some gain can be expected from noise cancellation. The influence on the performance of ETAM of a method of tow ship noise cancelling at hydrophone level (Inverse Beam Forming, IBF) is analysed. This approach increases ETAM performance by removing a loud and highly correlated noise source, the tow ship, and thus enhancing the other targets in the beam pattern. The results of the algorithms applied to two experimental datasets show that they bring an improvement close to theoretical expectations. Port starboard discrimination and the successful combination of IBF with ETAM make this approach innovative. In Chapter 3, methods for improving the localisation of a source with a short towed array are analysed and applied to data, both simulated and measured at sea. Localisation performance with sonar towed array is related to the array length. The knowledge of the position of a given acoustic source gives a critical tactical advantage to a ship. There are a limited number of ways to estimate the range of a source with a towed passive sonar, most requiring the towing platform to execute a manoeuvre. These manoeuvres are undesirable as they take a lot of time, cause bending of the towed array and can even put the towing platform in harm’s way. We present a number of source position estimation methods for both broadband and narrowband sources suitable for short towed arrays. Recursive methods based on the extended Kalman filter are first examined. A new method based on the integration of time delay of arrival measurements along the sonar path is described. We derive theoretical performance indicators and show that this method gives the possibility to estimate the position and speed of a source without a manoeuvre. In Chapter 4, the Classification performance of a broadband waveform is analysed and measured on data collected at sea. Like any long-range active sonar system, LFAS produces a large amount of unwanted sea bottom echoes or clutter. These echoes give rise to false alarms that increase the computational load of target trackers and jeopardise the correct classification of each echo. The number of false alarms due to clutter can be reduced either through echo classification techniques or through Doppler filtering provided the targets of interest are in motion. Much research has been carried out on waveform investigation for the efficient use of bandwidth capabilities of modern sonar transmitters. Among the quantity of waveforms, Binary Phase Shift Keyed (BPSK) pulses have emerged as exhibiting cross-correlation properties relevant to Doppler filtering while maintaining a range resolution comparable to Frequency Modulated (FM) pulses. We have successfully applied a false alarm reduction technique using contacts obtained with an FM pulse subsequently processed by Doppler filtering with a BPSK pulse. The Doppler classification performance for this pulse is evaluated on an experimental dataset and a few limitations of BPSK are identified.","sonar; detection; classification; localisation; signal processing; time delay; waveform","en","doctoral thesis","TNO","","","","","","","","Aerospace Engineering","Aircraft Transport and Operation","","","",""
"uuid:27899eb2-f29a-4a83-a229-8fbeec6a2b3c","http://resolver.tudelft.nl/uuid:27899eb2-f29a-4a83-a229-8fbeec6a2b3c","Advances in Model-Based Design of Flexible and Prompt Energy Systems -- The CO2 Capture Plant at the Buggenum IGCC Power Station as a Test Case","Trapp, C.","Colonna, P. (promotor)","2014","Pre-combustion CO2 capture applied to integrated gasification combined cycle (IGCC) power plants is a promising technical solution to reduce CO2 emissions due to fossil-fuelled electricity generation in order to meet environmental targets in a carbon-constrained future. The pre-combustion capture process allows to effectively remove CO2 from synthetic gas prior its combustion at high partial pressures. In addition, the net energy efficiency of decarbonised IGCC plants is estimated to be higher than that of conventional pulverized coal steam power plants integrating carbon capture. However, the removal of CO2 leads to a high efficiency penalty for the thermal power plant and an increase in system complexity. Moreover, the integration of carbon capture into the very complex gasification process and combined cycle power plant leads to technical problems as far as dynamic operation is concerned. Transient performance of future IGCC power plants becomes extremely relevant in order to balance the rapidly growing share of electricity converted from inherently intermittent renewable sources, such as wind and solar energy. The work documented in this thesis was part of a larger research project involving the utility company Vattenfall, the Energy research Centre of the Netherlands (ECN) and the Delft University of Technology aimed at the development of pre-combustion CO2 capture technology to be applied in a future commercial-scale IGCC power plant. A unique, fully instrumented CO2 capture pilot plant was realized at the Buggenum IGCC power station in the Netherlands in order to demonstrate the technology, to investigate its performance and to generate data for model validation. The most relevant research objectives of this thesis are to improve and develop general tools and methodologies which i) facilitate detailed steady-state performance analysis and sophisticated optimization of process design and operating conditions and ii) enable studies on process dynamics already during the early design phase in order to support the choice of equipment and control strategies aiming at the improvement of transient performance. The tools and methods are developed for the case-specific analysis of the pre-combustion CO2 capture plant at the Buggenum IGCC power station. With respect to generalization, it is worth to highlight that the adopted system engineering techniques and tools are applicable to the design of a larger class of chemical and energy conversion systems with minor changes.","pre-combustion CO2 capture; IGCC power plants; process design optimization; dynamic performance","en","doctoral thesis","","","","","","","","2014-06-16","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","","",""
"uuid:8f648295-c060-4575-80ab-a2cd175813cf","http://resolver.tudelft.nl/uuid:8f648295-c060-4575-80ab-a2cd175813cf","On the development of a cooled metallic thermal protection system for spacecraft","Buursink, J.","Gürdal, Z. (promotor)","2005","To achieve a significant cost reduction for launch of payloads to space, it is essential that the launcher is reused to the largest possible extent, and that the maintenance and operations cost of this launcher are minimised. To achieve this, work is ongoing on metallic thermal protection systems (TPS) that hold the promise of much reduced maintenance cost compared to other types of TPS. Metals however have a lower temperature limit. To allow the use of metals at higher thermal loads, they can be cooled. A method of achieving this has been invented at TU Delft. The system consists of a metallic skin with at a short distance behind a porous layer saturated with water. The metallic skin radiates thermal energy to the porous layer where water is heated and then evaporated. The water ensures that the temperature of the porous layer remains relatively cool, while the evaporation uses a large amount of energy. The water vapour can be vented overboard, removing this energy from the system. This TPS can give an increase in allowable thermal load of 90% for a given temperature that allows use of a metallic TPS on locations where this was not possible without cooling. Tests were performed to check the basic operation of the system and the basic performance parameters were measured. The basic underlying physical phenomena were described and measured, computer models of varying levels of complexity were made and some initial designs of applications were made. A flight experiment was developed for an ESA mission which will fly in the near future.","thermal protection system; water cooling; reusable launcher","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:627f30e0-0a70-43f5-b4c8-043c36dda641","http://resolver.tudelft.nl/uuid:627f30e0-0a70-43f5-b4c8-043c36dda641","Cybernetics of Tunnel-in-the-Sky Displays","Mulder, M.","Mulder, J.A. (promotor); Stassen, H.G. (promotor)","1999","Consensus is growing that the flexibility gained with the introduction of programmable, electronic cockpit displays in the 1980s must be exploited to the full extent. An important candidate to become the primary flight display of future flight decks is the tunnel-in-the-sky display, a perspective flight-path display that shows the reference trajectory to be flown in a synthetic three-dimensional world. The usefulness of the tunnel display in the pilot manual aircraft control task is the subject of this thesis. The mainstream of tunnel display research is confined to empirical comparisons of the tunnel display with conventional displays. The approach taken in the present theoretical and experimental study is original and new as it is conducted from the perspective of cybernetics. A four-stage methodology is developed to study the fundamental characteristics of pilot/display interaction, based on a theoretical analysis of information, in particular the information used for control. The information analysis is conducted within the context of Gibson's ecological approach to visual perception. The information analysis provides novel insights into how the tunnel display geometric design variables can affect pilot behavior. To examine the validity of the theoretical hypotheses, six experiments have been conducted. Three experiments examined the effects of manipulating some of the main display design variables, such as the tunnel size, the viewing volume and the presence of guidance symbology. Another three experiments investigated the fundamental characteristics of the tunnel geometrical design in the tasks of following a trajectory that is either straight or circular, and in the task of conducting a curve-interception maneuver. The experiments show that the cybernetic, information-centered approach is indeed very successful in pin-pointing the important characteristics of pilot/display interaction. The experimental methodology employed in this thesis aimed at integrating the model-based approach with the common approach of collecting mainly performance-related data. It is described in detail how experiments can be designed with the objective of conducting a control-theoretic analysis. The limitations of some non-parametric identification methods in multi-axis, multiple loop tracking tasks are described. The use of criterion functions, in both the frequency and the time domain, in the parametric identification methods is also exemplified.","human-machine interface; cockpit displays; perspective displays; cybernetics; human performance modelling","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3392af2c-9ff5-4ccf-af2d-7829b95701cb","http://resolver.tudelft.nl/uuid:3392af2c-9ff5-4ccf-af2d-7829b95701cb","Design and Optimization of Filament Wound Composite Pressure Vessels","Zu, L.","Beukers, A. (promotor); Koussios, S. (promotor)","2012","One of the most important issues for the design of filament-wound pressure vessels reflects on the determination of the most efficient meridian profiles and related fiber architectures, leading to optimal structural performance. To better understand the design and optimization of filament-wound pressure vessels, in this dissertation we present an overview and comprehensive treatment for toroidal and domed pressure vessels. Since the geodesic winding has severe boundary conditions that confine the layup optimization, the non-geodesic trajectories are here extensively applied to enlarge the design space. Designing optimal laminate layup is not the only issue; the fibers must be stable on the mandrel and be exactly placed along trajectories as predetermined by structural design. To obtain a stable fiber trajectory, the stability-ensuring conditions are formulated in terms of both fiber slippage and bridging tendencies; these conditions provide the basic criteria for the subsequent design of various pressure vessels. The mathematical description of the geodesics and non-geodesics on a generic shell of revolution is briefly presented. A generalized optimality criterion that is adapted to various optimal design problems for pressure vessels is elaborated. This condition originates from the idea that the optimal pressure vessels are governed by the condition of equal shell strains, or equivalently, zero shear stress at lamina level. The specific equations and the feasible intervals of the optimality condition are also given for several types of laminations. The basic equations of the netting analysis and their applications to the design of circular toroidal pressure vessels are here outlined. The influence of the fiber layup and the geometry of the toroid on the stability of netting-dictated fiber trajectories are evaluated. A new possibility to improve the vessel performance can be offered by the application of adapted cross-sectional shapes instead of the conventional shapes. The isotensoid design, which leads to equal fiber tension throughout the whole structure, is conducted to determine the netting-based optimal cross-sectional shapes. The governing equations for determining geodesic and non-geodesic isotensoids are respectively derived and their feasible intervals are also determined. In addition, a simplified method for designing isotensoid pressure vessels with unequal polar opening is also outlined, with the aid of non-geodesic trajectories. The optimal design, based on orthotropic plate theory, is divided into two basic approaches: numerical and semi-analytical methods. A numerical optimization method is specially designed for determining the optimal meridian profiles of bellow-shaped pressure vessels. An integral design method is proposed for circular toroidal pressure vessels, with emphasis on the determination of the optimal non-geodesic trajectories and winding patterns. Based on the previously-obtained (generalized) optimality condition, semi-analytical design methods are presented for the determination of the optimal meridian profiles for continuum-based domes and toroids, respectively. The optimal cross sectional shapes lead to significantly improved vessel performance. An extensive study of the manufacturing of filament wound toroidal pressure vessels is conducted. We here emphasize the importance of suitable winding patterns for obtaining an optimal pressure vessel, and we accordingly derived the ""Diophantine""-alike pattern equations that produced such patterns. The main objective of the method presented here is to match the structure-dictated number of wound circuits to the solution of the pattern equations for determining the proper winding velocities of the mandrel and the feed eye. In addition, depending on the aimed lathe machine configuration, the underlying geometric model of the new-fashioned toroidal winder is outlined and the kinematic solutions for coupling the motion of the mandrel and the feed eye are also given. Simulations of geodesic and non-geodesic trajectories are performed for winding toroidal pressure vessels. Last but not least, since ultra-high pressure vessels require thick-walled designs, this dissertation is also extended to three-dimensional problems where the through-thickness stress gradient is taken into account. A three-dimensional (3D) elasticity analysis on multi-layered thick-walled pressure vessels is here addressed. In order to better understand the design approaches of thick-walled composite cylinders and find ways to improve their structural performance, a review is devoted to 3D elasticity approaches for obtaining the exact solutions of the stresses and strains induced by internal pressure, and the effects of hygrothermal loading and twisting. The 3D effective elastic constants and most frequently used failure criteria for cylindrically anisotropic materials are also presented.","composite pressure vessel; filament winding; non-geodesic; isotensoid; thick-walled design","en","doctoral thesis","BOXPress","","","","","","","","Aerospace Engineering","Design and Production of Composite Structures","","","",""
"uuid:d6b06571-051b-44d4-88ef-5a4e71251388","http://resolver.tudelft.nl/uuid:d6b06571-051b-44d4-88ef-5a4e71251388","LCC-OPS: Life Cycle Cost Application in Aircraft Operations","Suwondo, E.","Smit, K. (promotor); Diran, O. (promotor)","2007","Observation of current practices in aircraft operations and maintenance shows limited consideration of cost savings applied by aircraft modifications, maintenance program optimisation and aircraft selection. This is due to hidden (maintenance dependent) costs and difficulties in quantifying the utilisation of a higher availability or reduction of revenue losses. Hidden costs can be a significant portion of operating costs and could be reduced by a better aircraft reliability. Most of the decisions for aircraft modification and maintenance program optimisation are made only to fulfil airworthiness or operational requirements. The considerations for the impact of aircraft reliability and maintenance dependent costs on life cycle cost are limited during aircraft selection, because operational data is very limited and the methods to quantify technical delays and cancellations are not available. This situation can be improved by a better quantification of the required investment and the savings achieved by a proper evaluation of the implemented modifications and maintenance program optimisations. In this thesis a Life Cycle Cost model is developed, called LCC-OPS, which visualises the hidden costs and quantifies opportunity revenues or losses. This model will provide an objective calculation and evaluation of the current and projected alternatives.","","en","doctoral thesis","Bandung, ITB Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:09e27e41-c1bb-4374-9509-4b4970033da3","http://resolver.tudelft.nl/uuid:09e27e41-c1bb-4374-9509-4b4970033da3","Multigrid Implementation of Cellular Automata for Topology Optimisation of Continuum Structures with Design Dependent loads","Zakhama, R.","Gürdal, Z. (promotor); Smaoui, H. (promotor)","2009","Topology optimisation of continuum structures has become mature enough to be often applied in industry and continues to attract the attention of researchers and software companies in various engineering fields. Traditionally, most available algorithms for solving topology optimisation problems are based on the global solution approach and require a large number of costly analyses. An alternative methodology, based on cellular automata (CA) and accelerated with a multigrid discretisation scheme, can be a good candidate to solve topology optimisation problems in a reasonable amount of computational time. The main advantages of using CA paradigm in structural design are the local analysis and design resolutions, and its parallel nature. The multigrid acceleration method is used to improve its efficiency. This innovative approach offers a new paradigm for design and analysis with higher efficiency compared to existing design optimisation algorithms. In this thesis, the topology optimisation of continuum structures with design-dependent loads is solved using a multigrid accelerated cellular automata algorithm. The CA paradigm is applied to two and three dimensional continuum topology optimisation problems. An optimisation formulation based on minimum compliance design subject to a volume constraint is used in the present work. The cellular automata based design scheme uses local update(s) rules for both field variables (displacements) and design variables (cell densities). The analysis rules are derived from the principle of minimum total potential energy, and the design rules are derived based on continuous optimality criteria interpreted as local Kuhn-Tucker conditions. Numerical experiments demonstrate the robustness of the proposed CA algorithm to solve topology optimisation problems at the expense of slow convergence. The deterioration of CA convergence rate is due to slow propagation of information from cell to cell as the number of variables increases. A methodology based on multigrid scheme is used to accelerate the CA design algorithm. The multigrid acceleration scheme uses different discretisation levels of grids. The CA iterations on the finest grid are coupled with the iterations of the correction solution on the coarse grids. The multigrid accelerated CA algorithm is demonstrated to be a powerful tool for solving topology optimisation problems compared to other algorithms based on finite element analysis. The computational cost using this scheme is found to be proportional to the number of cells. The topology optimisation of continuum structures is also performed under the influence of design-dependent loads. A direct density based method that does not involve explicit construction of the loading surfaces is developed to define the design-dependent loads. The optimization problem is solved by the modified Method of Moving Asymptotes coupled with line search (MMALS), and by multigrid accelerated CA algorithms. An explicit constraint is added to the formulation to lead a design to a close pure black/white solution. Numerical examples demonstrate that the multigrid accelerated CA algorithm convergence is more stable and more robust than the MMALS algorithm. The proposed algorithms demonstrates the effect of design-dependent loading onto the topology optimisation problem as illustrated by creating extra elements, shape modifications or void appearing.","Topology optimisation; Continuum structures; Multigrid; Cellular automata; Design-dependent loads","en","doctoral thesis","TUDelft, Faculteit Luchtvaart-en Ruimtevaarttechiek","","","","","","","","Aerospace Engineering","Aerospace Structure","","","",""
"uuid:1b627a9d-2d37-4b82-92fc-392463605445","http://resolver.tudelft.nl/uuid:1b627a9d-2d37-4b82-92fc-392463605445","A Reconfigurable GPS/Galileo Receiver Front-end for Space Applications","Noroozi, A.","Gill, E.K.A. (promotor)","2013","The trend of space technology developments is moving from high power consuming, bulky and costly systems towards low-power, small, low-cost and flexible systems. Thus, the spacecraft can benefit from multi-purpose and flexible systems which can be low-power and low-cost by employing new technology. One example of such system is a GNSS receiver capable of adapting the number of used frequency bands depending on its power constraint and the required accuracy. In the past, a Global Navigation Satellite System (GNSS) receiver has primarily been used for navigation purposes. However, as the number of available GNSS systems has increased, the potential of introducing new applications using these systems has also increased. Such applications become more robust and their performance can be improved if the GNSS receiver can operate with more than one GNSS system. On the other hand, extensive research and developments in state-of-the-art integrated circuit (IC) technology facilitates the integration of complex systems in a very compact and efficient manner. This miniaturization can be spun into space applications which are very complex systems by itself. Using this potential leads to new approaches in spacecraft design as well as potentially new space applications which may require short time-to-market. The research objective of this thesis is to develop a space-capable, flexible, multipurpose, low-power and low-cost GNSS receiver front-end. This front-end shall be able to process GNSS signals from different GNSS systems and different frequency bands. In chapter 1, an overview of navigation systems along with applications of GNSS systems is presented. This chapter also provides and introduction to state-of-the art IC technology and its advantages and disadvantages for using it in space. Thesis objectives and research questions conclude this chapter. Chapter 2 covers the fundamentals of satellite positioning system and provides a detailed explanation of GPS and Galileo signal structures followed by investigating a generic GNSS receiver architecture. This chapter is concluded with explanation of requirements for designing a space capable GNSS receiver. In chapter 3, existing radio receiver front-end architectures are reviewed and compared. The most suitable architecture, i.e. zero-IF, is selected. Finally, an innovative and flexible architecture for GNSS receiver front-end based on zero-IF is proposed. Chapter 4 begins with technology selection and calculations of link budget of the proposed receiver front-end. It is followed by reviewing various implementations of building blocks of the front-end and their comparison. In this chapter an innovative mixer architecture for zero-IF architecture is proposed which overcomes its two main problems, the DC offset and flicker noise. The chapter concludes by selecting the most suitable circuits for mixer, quadrature oscillator and analog to digital converter (ADC) for this receiver front-end. In chapter 5, the circuits of the mixer, quadrature oscillator, amplifier and ADC are developed in transistor level followed by verification simulations. The results of the simulations verify the expected behavior of the proposed mixer as well as the quadrature oscillator, amplifier and ADC. The thesis is concluded in chapter 6 with summary of the results, recommendations and future outlook.","GNSS; GPS; Galileo; receiver; front-end; space; zero-IF; navigation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:2e535954-fb97-453f-8365-6e0fb8f17430","http://resolver.tudelft.nl/uuid:2e535954-fb97-453f-8365-6e0fb8f17430","Development and application of a hypersonic flow solver","Walpot, L.M.G.F.M.","Bakker, P.G. (promotor)","2002","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:38aa1c82-f543-42e9-b55c-f0a1b51c0214","http://resolver.tudelft.nl/uuid:38aa1c82-f543-42e9-b55c-f0a1b51c0214","Microchemistry in aluminium sheet production","Lok, Z.J.","Van der Zwaag, S. (promotor)","2005","The production of aluminium sheet alloys from as-cast ingots is a complex process, involving several rolling operations in combination with various thermal heat treatments. Through their influence on the alloy microchemistry and microstructure, these thermomechanical treatments are all aimed at controlling the final material properties. In addition, microchemistry and microstructure also affect each others development, which makes their control during industrial processing a rather complex issue. For this reason an EU-supported project under the name VIR[*], was started in March 2000, in which several European aluminium producers and research institutes co-operated in developing physically based models for the microchemistry and microstructure evolution during industrial processing of non heat-treatable aluminium alloys. The present PhD-research is part of the VIR[*] results and focusses at the influence of microstructure on the Mn precipitation in a commercial Al-Mn-Fe-Si alloy (AA3103). Firstly, several techniques for measuring the concentration of aluminium alloying elements in solid solution, are evaluated. Measurement of the thermoelectric power (TEP) proves to be the most reliable technique. As opposed to electrical resistivity and microprobe analysis, its signal is hardly influenced by alloy features other than solute atoms (e.g. precipitates). It is also shown that by combining TEP and resistivity, it is possible to independently measure the Fe and Si solute levels in a commercial Al-Fe-Si alloy. Subsequently, commercial AA3103 was solutionised, hot rolled and annealed under laboratory conditions. TEP measurements show that the precipitation of solute Mn slows down significantly as the material recrystallises. It is assumed that a large difference in Mn diffusivity between the deformed and undeformed microstructure is responsible for this effect. This observation serves as basis for a quantitative precipitation model that is also able to include the effects of an evolving microstructure. Finally, the predictive power of the precipitation model is tested. After coupling with a VIR[*] microstructure model, the microchemistry predictions are compared with measurments on AA3103 samples taken from various stages of the industrial processing route. It shows that, although not always quantitatively accurate, the measured microchemical trends are well reproduced.","aluminium alloys; solutes; precipitation; deformation; modelling","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5405aa05-d1e4-4f09-b476-cb53295dd700","http://resolver.tudelft.nl/uuid:5405aa05-d1e4-4f09-b476-cb53295dd700","Wall-Shear Stress Measurements with Quantitative Infrared-Thermography","Mayer, R.","van Ingen, J.L. (promotor)","2000","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c13e3938-8b05-4228-8e84-4e9709c934af","http://resolver.tudelft.nl/uuid:c13e3938-8b05-4228-8e84-4e9709c934af","The Near Side: Regional Lunar Gravity Field Determination","Goossens, S.","Ambrosius, B.A.C. (promotor); Visser, P.N.A.M. (promotor)","2005","In the past ten years the Moon has come fully back into focus, resulting in missions such as Clementine and Lunar Prospector. Data from these missions resulted in a boost in lunar gravity field modelling. Until this date, the lunar gravity field has mainly been expressed in a global representation, despite the lack of data over the far side of the Moon, which is the result of the spin-orbit resonance the Earth and Moon are in. To extract the wealth of information about the near side present in tracking data of the Lunar Prospector spacecraft, the global formulation is not efficient and regional representations become of interest. They can be used to derive accurate and high-resolution local gravity anomaly maps of the near side, which can help to understand the structure and evolution of the Moon, and consequently the Earth-Moon system, as they provide the boundary conditions for internal processes and structure. This dissertation presents a method for the regional recovery of gravity from satellite tracking data, in order to improve the resolution and accuracy of current lunar gravity field models and in order to exploit the high-resolution gravity information present in the data, without significant interference from the unknown far side. The recovery method has been applied to Lunar Prospector tracking data to create high-resolution solutions for parts on the near side of the Moon. The use of such a recovery method is not limited to one celestial body only and will be very valuable in planetary geodesy. Current and future dedicated gravity satellite missions should provide ample opportunity to apply a method as presented in this dissertation.","lunar gravity; regional gravity; gravity field determination","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5f9ccff3-5d7b-4374-b308-532de0c4d783","http://resolver.tudelft.nl/uuid:5f9ccff3-5d7b-4374-b308-532de0c4d783","Fatigue Crack Growth in Riveted Joints","Fawaz, S.A.","Vogelesang, L.B. (promotor); Schijve, J. (promotor)","1997","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a5a8d77b-0277-40b0-ba01-4b6a51b4e3a4","http://resolver.tudelft.nl/uuid:a5a8d77b-0277-40b0-ba01-4b6a51b4e3a4","Complexity Aspects in Design for Sustainability","Schroijen, M.J.T.","Van Tooren, M.J.L. (promotor)","2011","Anthropogenic environmental impact is growing despite large technical efforts to reduce it. Its dependency on technology induced human behaviour makes designing for environmental impact reduction particularly difficult. Despite the fact that the sustainable conundrum is characterized as a “no technical solution problem”, a framework is proposed in support of environmental impact reducing technology design. The goal is to provide a means to allow a priori evaluations of product design in a true stakeholder setting. The basis of the framework is formed by Quality Function Deployment (QFD), Value Engineering (VE) and Multidisciplinary Design Optimization (MDO), which allow for addressing the complexities at system and system-of-systems level by dedicated and tailored tools. This set of tools consists of Agent Based Modelling and Simulation (ABMS), Bi-Level Integrated Systems Synthesis (BLISS) and Bayesian Statistics. The design for sustainability support provided by each of these tools is illustrated by a different realistic show case. Since aviation possesses all complexities of the sustainable conundrum, it is used as a challenging example to illustrate the proposed tools. The show cases used, MagLev launch system, Prandtl Plane, Blended Wing Body, Propeller aircraft and Coand? plane, are a subset of the diverse range of solutions proposed to reduce environmental impact. This framework is a first step on the long way required to arrive at a truly sustainable product design process.","Sustainable Design; Complexity; Agent Based Modelling and Simulation; Multidisciplinary Design Optimization; Bayesian Statistics","en","doctoral thesis","M.J.T.Schroijen","","","","","","","","Aerospace Engineering","Systems Engineering and Aircraft Design","","","",""
"uuid:c5c1cc48-f2a1-4dcd-ac04-50e59f7e0cf6","http://resolver.tudelft.nl/uuid:c5c1cc48-f2a1-4dcd-ac04-50e59f7e0cf6","Decision Support for Collaborative Airport Strategic Planning","Wijnen, R.A.A.","Walker, W.E. (promotor); Curran, R. (promotor)","2013","An airport’s operation and development impacts many stakeholders. Therefore, an airport should be treated as a socio-technical system. An airport operator and its stakeholders should strategically plan and develop the airport together. This dissertation describes the development of the HARMOS Decision Support System that can facilitate such collaborative strategic planning.","airport strategic planning; domain driven design; policy analysis; collaboration; socio-technical system","en","doctoral thesis","TRAIL Research School","","","","","","","","Aerospace Engineering","Aerospace Design, Integration & Operations","","","",""
"uuid:de6aef44-7d24-49aa-9485-064c52a147fa","http://resolver.tudelft.nl/uuid:de6aef44-7d24-49aa-9485-064c52a147fa","Isogeometric design optimisation","Nagy, A.P.","Gürdal, Z. (promotor); Abdalla, M.M. (promotor)","2011","Design optimisation is of paramount importance in most engineering, e.g. aeronautical, automotive, or naval, disciplines. Its interdisciplinary character is manifested in the synthesis of geometric modelling, numerical analysis, mathematical programming, and computer sciences. The evolution of the field is closely related to concomitant advances in these diverse research areas. Historically, there has always been a strong desire to unify these equally important fields of contemporary engineering. However, creating sophisticated computer-aided engineering (CAE) systems that nicely integrate these elements remained a formidable matter thus far. The purpose of this work is to demonstrate that computer-aided geometric design (CAGD), physical analysis, and design optimisation are inherently joint engineering endeavours and maybe beneficially integrated in a common framework. The inspiration of this work emanates from the recently introduced isogeometric analysis. The isogeometric paradigm is aimed at unifying the geometric and analysis descriptions of engineering problems. This unification is brought about by integrating the geometric description of a design and its analysis. Consequently, the isogeometric approach provides a natural environment to develop design optimisation tools. In this dissertation, a comprehensive non-uniform rational B-splines (NURBS) based isogeometric structural design optimisation framework is introduced. The proposed design framework is developed for sizing, form finding, and the coupled optimisation of form and sizing. Salient elements of isogeometric design include distinct interpolation schemes, a multilevel design scheme, the shape change norm, and the variational constraint formulation. Harmony between the different components is emphasized through consistent use of isogeometric concepts and precepts. Owing to the weight-sensitive nature of most aerospace constructions, the primary focus is the design of Cosserat structures, particularly rods and shells of the Kirchhoff-Love class. It is however worth highlighting that the fundamental ideas introduced in this work are applicable to general structural models. The isogeometric design framework is first verified in the context of sizing and form finding of isotropic and elastic planar arches. Subsequently, the more challenging task of thin-walled variable stiffness composite shell optimisation is performed. Here, it is aimed at finding the optimal in-plane material anisotropy distribution as well as the shape. The considered mathematical programming problems are solved by utilising the technique of sequential convex conservative approximations (CCA). While separable CCAs are employed to deal with relatively large-scale structural sizing problems, a non-separable CCAs-based algorithm is developed to solve isogeometric form finding problems. The applicability of the framework is demonstrated using several example problems involving frequently employed design objectives and constraints, e.g. structural weight and stiffness, buckling load factor, fundamental frequency, or strength. The attained numerical results indicate good applicability of the proposed design framework.","isogeometric analysis; structural optimisation; form finding; stiffness tailoring; Cosserat continua","en","doctoral thesis","","","","","","","","2011-12-02","Aerospace Engineering","Aerospace Structures and Continuum Mechanics","","","",""
"uuid:edecee10-7db2-443e-8cdf-d41aaddaa1b2","http://resolver.tudelft.nl/uuid:edecee10-7db2-443e-8cdf-d41aaddaa1b2","Numerical simulations of flapping foil and wing aerodynamics: Mesh deformation using radial basis functions","Bos, F.M.","Bijl, H. (promotor)","2010","Both biological and engineering scientist have always been intrigued by the flight of insects and birds. For a long time, the aerodynamic mechanism behind flapping insect flight was a complete mystery. Recently, several experimental and numerical flow visualisations were performed to investigate the aerodynamics around flapping wings. Flapping wings produce both lifting and propulsive forces such that it becomes possible for insects and smaller bird species, e.g. hummingbirds, to stay aloft and hover, but also to perform extreme manoeuvres. Because of this versatility, insects and smaller birds are an inspiration for the development of flapping wing Micro Air Vehicles, small man-made flyer's to use in exploration and surveillance. In this thesis, Computational Fluid Dynamics methods are used to resolve the flow around two- and three-dimensional flapping foils and wings. Flapping wings, at the scale relevant to insect flight, move at large rotation angles, which is difficult to handle in existing mesh motion solvers. Therefore, existing methods to deform the mesh have been compared and improved. A relatively new method is implemented, based on the interpolation of radial basis functions. Using the mesh motion based on radial basis function interpolation, the flow around flapping airfoils and wings at hovering and forward flight conditions has been investigated. The forces and vortex patterns have been studied, especially the influence of wing kinematics on the leading-edge vortex. In addition, preliminary results are described of the effects by active wing flexing.","Computational Fluid Dynamics; Mesh motion; Radial Basis Functions; Flapping wings; OpenFOAM","en","doctoral thesis","","","","","","","","2010-02-18","Aerospace Engineering","Aerospace Design, Integration & Operations","","","",""
"uuid:64c82a6e-6db0-4457-9c4f-2446653e5b9d","http://resolver.tudelft.nl/uuid:64c82a6e-6db0-4457-9c4f-2446653e5b9d","Segmentation and classification of airborne laser scanner data","Sithole, G.","Vosselman, M.G. (promotor)","2005","Various methods have been developed to measure the physical presence of objects in a landscape with high positional accuracy. A new method that has been gaining popularity is Airborne Laser Scanning (ALS). ALS works by scanning a landscape (the collection of ground, buildings, vegetation, etc.,) in multiple passes. In each scan pulses of laser light are emitted from an airborne platform and their return time is measured, thus enabling the range from the point of emission to the landscape to be determined. The product of airborne laser scanning is a cloud of points in 3D space. ALS is capable of delivering very dense and accurate point clouds of a landscape in a relatively short time. However, in spite of the ability to measure objects with high positional accuracy, the automatic detection and interpretation of individual objects in landscapes remains a challenge. An example of just such a challenge is the classification of point clouds produced by ALS. The classification of ALS point clouds consists firstly in the labeling of points as either object or bare earth. The labeled object points are then further labeled as either building or vegetation. As a measurement technique ALS holds great promise and motivated by the desire to promote it, research has been conducted here to automate the detection of bare earth, buildings and vegetation in ALS point clouds.","Lidar; filtering","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e0b49fa4-868a-4974-b659-62d05a3335f0","http://resolver.tudelft.nl/uuid:e0b49fa4-868a-4974-b659-62d05a3335f0","Low-Speed Model Support Interference - Elements of an Expert System","Horsten, B.J.C.","Eitelberg, G. (promotor)","2011","Wind tunnel support interference is one of the constraints affecting the quality of wind tunnel measurements. Several methods to determine the interference are experimental- empirical- and numerical methods. Experimental methods are often time consuming and costly. This also holds for empirical methods as they are founded on a vast number of experimental data sets. CFD is also found to be time consuming and sometimes computationally expensive. Future guidelines for the treatment of support interference aim at providing engineers more alternatives. Such alternatives require however an extensive knowledge on experiments and CFD: it requires the engineer to be an expert in the field, something that is often impossible. Engineers should therefore be guided by an expert system (a computer program that represents and reasons with knowledge of some specialist subject with a view to solving problems or giving advice) in their dealings with support interference. In this thesis such an application-based expert system is considered. The system focuses on low-speed model support interference on single sting mounted models carrying an internal balance. The research objective of this thesis is stated as: ''To identify the necessary elements for the design of an expert system for support interference on sting mounted models carrying internal balances applicable to low-speed wind tunnels.'' In this thesis the necessary components of such an expert system are identified through a study on the elements of its knowledge base and a study on a feasible structure of the system in terms of its applications. Considering the study on the elements of its knowledge base, experimental- and numerical research is carried out to gain intelligibility on support interference. It is shown that a support break down facilitating the treatment of disturbances of individual support parts spanning a certain setup is a systematic method to analyze support interference. The order of magnitude and the nature of the disturbances are not compromised when this approach is adopted provided that the amount of separate parts is kept to a minimum. This approach enables the crucial study on the disturbances of the model sting that causes the complete spectrum of support disturbances. Advantages of studying the sting include the possibility to generalize the research results to a wider class of support structures, allow for a qualitative analysis on the nature of near-field and far-field effects but also a qualitative and quantitative validation of several methods applied to determine support interference. Comparing measurements (balance measurements and 5-hole probe measurements) to calculations (panel code- and Euler calculations) on model sting near-field and far-field effects shows that without knowing the specific details of a complex interference flow field, it is not justified (from the viewpoint of accuracy) to determine model sting near-field and far-field effects using methods at low levels of complexity and intrinsic accuracy. Significant calculation offsets (out of the bounds of experimental accuracy) are caused by the action of the balance cavity and slit, vorticity and viscosity. In depth understanding of the limitations of these numerical methods (panel code, Euler) can only be developed when the interference flow field itself is understood both qualitatively and quantitatively. Navier-Stokes calculations are used for this purpose. Calculations provide a qualitative image of the interference flow field that complies with measurements. Quantitatively, the Navier-Stokes calculations are not able to determine the values of the interference with the right trends and within typical measurement (balance) accuracy. Gained near-field flow knowledge is used for an assessment of the potential of various numerical and experimental methods in determining the near-field and far-field model sting effects on wind tunnel models at low speed for various sting placements. This knowledge is generalized such as to cover the treatment of the remaining support for typical sting mounted setups. Considering the numerical and experimental treatment of support disturbances of any support part it is concluded that classification parameters ''accuracy'' and ''effort'' (classifying the various methods for the determination of the interference) oppose each other: accurate methods demand a lot of implementation effort and vice versa. This opposition can not be solved by designing a custom-made model (that is both accurate and requires a low amount of implementation effort) for calculating model support interference. Such a model should calculate the disturbance effects fast (by incorporating only the disturbance factors of primary quantitative interest) with the right trends and magnitude. Solving for the confinements of such models implies an inevitable reduction in the applicability range of the model. Typical custom-made models are unsuitable for implementation in the expert system. They reveal the following rule of thumb: ''High accuracy (at a minimum equal to typical balance Delta-measurement accuracy) and low implementation effort (total measurement effort or modeling effort and computational effort) of a correction method for determining model support interference are currently incompatible when a wide range of applicability (freestream conditions, setups) is desired''. This rule of thumb necessitates a more elaborate definition of the expert system's requirements on speed and accuracy, resulting in an expert system with an application-based structure. The applications with given accuracy and speed assist in four stages defining a typical commercial wind tunnel measurement: negotiations at the client, test preparation phase, performing the measurements and finally the post test corrections. Next a closer look is taken at a feasible structure of the expert system. The proposed application-based structure fulfills the expert system's main requirements: advise on the test setup/correction methods, calculate the interference fast enough and accurate enough pre-test and on-line, correct for the interference on-line and off-line and allow easy plug-in of modules dealing with the problem of wall interference. Additional requirements relate to the use of the system (meet computer platform standards and be user friendly with professional interfaces). Typical necessary system elements are identified: the expanded knowledge base on model support interference has resulted in two basic expert applications (ESI and ASID, directly applicable for measurements in the LLF of DNW for which they are customized) and new methods (VOLAER and MVL) to approach the problem of wind tunnel wall- and support interference. These products are seen as basic elements of an expert system (generalizable to other wind tunnels). MVL (a method combining both uncorrected wind tunnel measurements and vortex-lattice calculations) proves to be particularly valuable as it predicts the interference of wind tunnel walls, support and includes secondary interference (when e.g. the support is traversed close to the wind tunnel walls). MVL is suitable for all support setups in all types of wind tunnels provided a vortex-lattice method is used enabling an accurate representation of the model aerodynamic derivatives (preferably including the effects of viscosity). MVL's prediction capabilities necessitates the use of multiple boundary conditions (interference values) in order to guarantee a stable solution thereby categorizing it as an interpolation tool with the potential of decreasing the amount of necessary experimental balance Delta-measurements. Currently, a very basic variant of an expert system is presented in this thesis and its necessary elements are identified. This is seen as a good initiative towards meeting the future needs. It is believed that the future needs can be met when further development of this expert system is stimulated. Increasing data availability and updating the applications is of utmost importance in this matter. To the authors opinion, the data availability can be expanded to exceed the companies thresholds and to span multiple companies and countries. In this light, cooperation might very well be seen as the most important future need of all.","Support Interference","en","doctoral thesis","Boxpress Uitgeverij Oisterwijk","","","","","","","2011-06-24","Aerospace Engineering","Aerodynamics","","","",""
"uuid:74c60eed-9296-4d72-bd19-0c0005a84c63","http://resolver.tudelft.nl/uuid:74c60eed-9296-4d72-bd19-0c0005a84c63","Efficient Numerical Methods for Fluid-Structure Interaction","Michler, C.","De Borst, R. (promotor)","2005","Numerical solution methods for fluid-structure interaction are of great importance in many engineering disciplines. The computation of fluid-structure interactions is challenging on account of their free-boundary and multi-physics character. The different length and time scale discretization requirements of the fluid and structure subsystems typically translate into the use of non-matching meshes at the fluid-structure interface. Under such an incompatible discretization, maintaining the conservation properties at the fluid-structure interface is in general non-trivial. Moreover, the solution of the coupled fluid-structure equations by the customary subiteration method often lacks robustness and efficiency. These aspects provide the motivation for the research into conservative discretization techniques and efficient iterative solution methods for fluid-structure interaction presented in this thesis. We investigate an approach that enables conservation at the interface even for incompatible fluid and structure discretizations. Numerical results demonstrate the relevance of maintaining conservation at the fluid-structure interface for the stability and accuracy of the numerical solution. To overcome the deficiencies of the subiteration solution method, we propose to combine subiteration with GMRES acceleration. Since the acceleration can be confined to the degrees-of-freedom of the interface, the acceleration itself requires only negligible computational resources. Moreover, the combined method allows for the optional reuse of Krylov vectors in subsequent invocations of GMRES, which can considerably enhance the efficiency of the method. Since the proposed method retains the modularity of the underlying subiteration method, its implementation is straightforward in codes that already use subiteration as a solver. Detailed convergence studies and a comparison with standard subiteration demonstrate the effectiveness of the proposed solution method.","Fluid-structure interaction; partitioning; subiteration; GMRES; Newton-Krylov methods; efficiency; energy conservation; space/time finite-element method","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2e17121a-d138-4c14-bf1f-421799602beb","http://resolver.tudelft.nl/uuid:2e17121a-d138-4c14-bf1f-421799602beb","New concepts for organic Rankine cycle power systems","Casati, E.I.M.","Colonna, P. (promotor); Dossena, V. (promotor)","2014","Energy provision is one of the major challenges for the Human Society, and it is increasingly clear that the current production/consumption model is not sustainable. The envisaged energy system is smarter, more decentralised and integrated. Energy conversion systems based on the organic Rankine thermodynamic cycle (ORC) have the potential to play a major role in this framework, being one of the most proven solutions for the exploitation of external thermal sources in the power-output range from, say, few kWe, up to tens of MWe. In ORC power converters, a phase-changing organic compound is adopted as the evolving fluid which, following the working principle defining the Rankine cycle, allows to exploit a given source in order to convert part of its energy content into useful outputs, such as, e.g., mechanical, electrical, and thermal energy. The ORC energy converters are extremely flexible in nature, and able to exploit a virtually infinite variety of thermal sources. At the same time, this poses great challenges from the design point of view. Innovative concepts can be devised drawing from the fundamentals of the working fluid behavior, passing to the component- and up to the system-level of detail, but the corresponding generalized design methodologies have to be concurrently developed and integrated. The work documented in this thesis aims at contributing to these topics, by presenting the original results of numerical and experimental research investigating the potential of molecularly heavy and complex organic compounds as working fluids for the ORC power systems of the future.","ORC; energy systems; organic fluids","en","doctoral thesis","","","","","","","","2014-10-05","Aerospace Engineering","AWEP - Propulsion & Power group","","","",""
"uuid:2a2be734-39cc-4420-9ee9-a08883ee7a36","http://resolver.tudelft.nl/uuid:2a2be734-39cc-4420-9ee9-a08883ee7a36","Quantification of Modelling Uncertainties in Turbulent Flow Simulations","Edeling, W.N.","Bijl, H. (promotor); Cinnella, P. (promotor)","2015","The goal of this thesis is to make predictive simulations with Reynolds-Averaged Navier-Stokes (RANS) turbulence models, i.e. simulations with a systematic treatment of model and data uncertainties and their propagation through a computational model to produce predictions of quantities of interest with quantified uncertainty. To do so, we make use of the robust Bayesian statistical framework, in which the uncertainty is represented by probability. The first step toward our goal concerned obtaining estimates for the error in RANS simulations based on the Launder-Sharma k-e turbulence closure model, for a limited class of flows. In particular we searched for estimates grounded in uncertainties in the space of model closure coefficients, for wall-bounded flows at a variety of favourable and adverse pressure gradients. In order to estimate the spread of closure coefficients which reproduces these flows accurately, we performed 13 separate Bayesian calibrations. Each calibration was at a different pressure gradient, using measured boundary-layer velocity profiles, and a statistical model containing a multiplicative model inadequacy term in the solution space. The results are 13 joint posterior distributions over coefficients and hyper-parameters. To summarize this information we compute Highest Posterior-Density (HPD) intervals, and subsequently represent the total solution uncertainty with a probability box (p-box). This p-box represents both parameter variability across flows, and epistemic uncertainty within each calibration. A prediction of a new boundary-layer flow is made with uncertainty bars generated from this uncertainty information, and the resulting error estimate is shown to be consistent with measurement data. However, although consistent with the data, the obtained error estimates were very large. This is due to the fact that a p-box constitutes a unweighted prediction, essentially saying that every posterior distribution is equally applicable to the predictive scenario at hand, which is unlikely to be an accurate assumption. To improve upon this, we developed another approach still based on variability in model closure coefficients across multiple flow scenarios, but also across multiple closure models. The variability is again estimated using Bayesian calibration against experimental data for each scenario, but now Bayesian Model-Scenario Averaging (BMSA) is used to collate the resulting posteriors in an unmeasured (prediction) scenario. Unlike the p-boxes, this is a weighted approach involving turbulence model probabilities which are determined from the calibration data. Furthermore, BMSA incorporates scenario probabilities which are chosen using a sensor which automatically weights those scenarios in the calibration set which are similar to the prediction scenario. The methodology was applied to the class of turbulent boundary-layers subject to various pressure gradients. For all considered prediction scenarios the standard-deviation of the stochastic estimate is consistent with the measurement ground truth. Furthermore, the mean of the estimate is more consistently accurate than the individual model predictions. The BMSA approach results in reasonable error bars, which can also be decomposed into separate contributions due to coefficient uncertainty, model inadequacy and variability of posteriors over different scenarios. However, to apply it to more complex topologies outside the class of boundary-layer flows, surrogate modelling techniques must be applied. The Simplex-Stochastic Collocation (SSC) method is a robust surrogate modelling technique used to propagate uncertain input distributions through a computer code. However, its use of the Delaunay triangulation can become prohibitively expensive for problems with dimensions higher than 5. We therefore investigated means to improve upon this bad scalability. In order to do so, we first proposed an alternative interpolation stencil technique based upon the Set-Covering problem, which resulted in a significant speed up when sampling the full-dimensional stochastic space. Secondly, we integrated the SSC method into the High-Dimensional Model-Reduction framework in order to avoid sampling high-dimensional spaces all together. Finally, with the use of our efficient surrogate modelling technique, we applied the BMSA framework to the transonic flow over an airfoil. With this we are able to make predictive simulations of computationally expensive flow problems with quantified uncertainty due to various imperfections in the turbulence models.","Uncertainty Quantification; RANS; Bayesian statistics","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:1f1b3e5c-72b8-440c-8d98-4b4c82814fb6","http://resolver.tudelft.nl/uuid:1f1b3e5c-72b8-440c-8d98-4b4c82814fb6","Distortions and Residual Stresses of GLARE Induced by Manufacturing","Abouhamzeh, M.","Benedictus, R. (promotor)","2016","GLARE is used in fuselage panels for its improved fatigue and residual strength. In this thesis, predictive models are developed for residual stresses and distortions of GLARE induced by manufacturing. Material behaviour of the epoxy adhesive and the glass-epoxy prepreg is characterised for thermal and curing circumstances. The derived temperature dependent viscoelastic properties can also be used in other applications in which time and/or temperature changes are of concern. The results of this research are important for three main reasons: first, the material thermo-viscoelastic response is derived for the first time and the thermal properties differ from the ones already used in literature for the design of panels made of GLARE. Second, two new models are developed, applicable to any orthotropic material including Fibre Metal Laminates, for cure and thermo-viscoelastic analyses. Third, the predicted residual stresses can improve the design where properties like fatigue and residual strength need to be considered. With the developed models, other effects like cutting, bonding doublers and stringers can be simulated to obtain the results for a completely featured fuselage panel made of GLARE.","Orthotropic; Fibre Metal Laminates; Residual Stresses; Distortions; Cure; Thermo-Viscoelastic","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:46f98920-672a-4d09-8831-368adf04fec2","http://resolver.tudelft.nl/uuid:46f98920-672a-4d09-8831-368adf04fec2","High Order Time-Accurate Partitioned Simulation of Unsteady Conjugate Heat Transfer; Analysis and Application of Implicit Runge-Kutta Time Integration Schemes","Kazemi Kamyab, V.","Bijl, H. (promotor); Van Zuijlen, A.H. (promotor)","2013","Time-accurate simulations of the thermal interaction of flows and structures, also referred to as conjugate heat transfer (CHT), can be computationally expensive. Furthermore, given the multi-physics nature of many engineering problems, resolution of other coupled phenomena, in addition to CHT, may also be of interest. This thesis aimed at developing a flexible and efficient numerical procedure for solving unsteady (transient) conjugate heat transfer. High order time integration schemes are considered, in place of commonly used second order implicit schemes, to reduce the computational work of advancing the coupled problem in time. For flexibility, the partitioned method is adopted for solving the coupled problem. For strongly coupled problems, a strongly-coupled solution algorithm is presented where high order explicit first stage singly diagonally implicit Runge-Kutta (ESDIRK) schemes are used for time integration. For Dirichlet-Neumann conditions at the interface, stability and rate of convergence of subiterations at each stage are analyzed analytically. Based on the analysis, the domain with the higher effusivity is assigned the Neumann condition and the one with the lower effusivity the Dirichlet condition. Furthermore, the interface iterations converge with a rate approximately given by the ratio of thermal effusivities of the subdomains. For weakly coupled problems, an order preserving loosely coupled solution algorithm is presented in which a family of high order implicit-explicit (IMEX) Runge-Kutta schemes are used for time integration. The IMEX schemes consist of the ESDIRK schemes for advancing the solution in time within each subdomain, and equal order and number of stages explicit Runge-Kutta (ERK) schemes for explicit integration of part of the coupling terms. Based on a stability investigation, when the ratio of thermal effusivities of the subdomains is much smaller than unity, it is possible to take large Fourier numbers using the loosely coupled algorithm. Another topic studied in this thesis is the application of high order ESDIRK schemes to cell-centered collocated finite volume discretization of unsteady incompressible Navier-Stokes equations. In particular, a face-velocity interpolation procedure (Rhie-Chow) which preserves the temporal design order of the multi-stage ESDIRK schemes is introduced. The influence of iterative errors on temporal order is minimized by using an iterative time advancing algorithm.","conjugate heat transfer; partitioned method; high order time integration; implicit Runge-Kutta; stability analysis; incompressible Navier-Stokes; collocated Finite Volume; consistent Rhie-Chow interpolation","en","doctoral thesis","","","","","","","","2015-04-01","Aerospace Engineering","Aerodynamics","","","",""
"uuid:ca471701-2817-4a36-9839-4545c1cceb45","http://resolver.tudelft.nl/uuid:ca471701-2817-4a36-9839-4545c1cceb45","3D flows near a HAWT rotor: A dissection of blade and wake contributions","Micallef, D.","Van Bussel, G.J.W. (promotor)","2012","Investigating the flow physics in the vicinity of the wind turbine blade is a challenging endeavour. In the past, focus was placed on the understanding of near wake flows arising from wake vorticity and the rotor loading. In this work, a different approach is taken by considering the flow field in the blade vicinity as a consequence of the separate effects of bound and wake vorticity. This enables new insight regarding the role of the blade as having a direct influence on the three-dimensional flow. The approach is applied for the reference axial flow condition and hence for the yawed flow condition where the issue of flow three-dimensionality takes a new level of complexity. Three research hypotheses are investigated in this work: 1. Radial flow components especially close to the wind turbine blade are not negligible. This contradicts the classical momentum approach which treats the flow as two-dimensional. The situation for yawed flow is even more important since wake vorticity not only exhibits an expansion but also a skewness. A fundamental understanding of the behaviour of the radial flow component is hence of paramount importance. 2. The three-dimensional flow field close to a Horizontal Axis Wind Turbine (HAWT) rotor is due to the effects of body and wake vorticity. The blade tip shape plays a fundamental role on the behaviour of the flow field near the blade. 3. The tip vorticity for axial and yawed flow results in a different tip flow behaviour. The hypotheses are linked by a common goal; to establish new insight into three-dimensional flows in the proximity of the rotor in yawed flow, using axial flow as a baseline investigation. Both numerical and experimental approaches have been used to investigate these hypotheses. A 3D unsteady potential flow panel model is used for the numerical computations. The model permits to decompose flow due to diff erent vorticity components. Stereo Particle Image Velocimetry (SPIV) is used for the experimental measurements. This enables measurement of all velocity components in a 2D plane and can then be used to construct a 3D volume of data. Flow data from three different rotors is used: SPIV measurements from the Model Experiments in Controlled Conditions (MEXICO) rotor in the German-Dutch DNW wind tunnel and experiments performed in the Open Jet Facility of TU Delft on two different 2m diameter rotors. The thesis is structured into six parts as follows: Part I - Literature review to support and contextualize the research Part II - Analysis of the hypotheses on ow three-dimensionality Part III - Decomposition of velocities in the rotor proximity Part IV - Origins and dynamics of vorticity Part V - Conclusions Part VI - Appendices The results presented in this thesis challenge the current understanding of flow three-dimensionality in the rotor plane particularly for the yawed flow case. The blade's role as a vorticity generator as well as its active role in disturbing the flow due to its vorticity distribution are both supported. The creation of a HAWT tip vortex over the blade thickness is studied leading to important implications about the induced flow field at the tip. The details of flow three-dimensionality due to the complex behaviour of the tip vortex upon release are presented and the implications of this discussed. The outcome of this research bridges the gap between existing knowledge of the flow on the rotor scale to future lines of research which will be directed to the study of boundary layer flows of rotating blades. By extensively analyzing the rotor blade scale outer flow (outside of the boundary layer) this research gives impetus to a necessary revision of tip corrections in the application to the industry standard BEM design codes which to this day rely on models which are not based on the detailed knowledge of rotor blade flow which this research provides.","horizontal axis wind turbine; rotor aerodynamics; Particle Image Velocimetry; blade tip","en","doctoral thesis","","","","","","","","2013-04-10","Aerospace Engineering","DUWIND","","","",""
"uuid:867c84ae-6cf5-45aa-ba5f-ab6ec4bbf5ed","http://resolver.tudelft.nl/uuid:867c84ae-6cf5-45aa-ba5f-ab6ec4bbf5ed","Energy-based Aeroelastic Analysis and Optimisation of Morphing Wings","De Breuker, R.","Gurdal, Z. (promotor)","2011","Morphing aircraft can change their shape radically when confronted with a variety of conflicting flight conditions throughout their mission. For instance the F-14 Tomcat fighter aircraft, known from the movie Top Gun, was able to sweep its wings from a straight wing configuration to a highly swept version. Such concepts, which are basically rigid body morphing concepts, have been developed further into aircraft which are able to have a distribution of morphing deformations over their wing, exhibiting large elastic straining of the skin. Most popular examples are the Lockheed-Martin Folding Wing concept, and the NextGen Aeronautics Batwing concept. A problem that became apparent from the literature is that there exists no dedicated conceptual design tools for morphing wings. The main focus in the literature has been on design and optimisation of predefined morphing mechanisms. Therefore the research presented in this dissertation focuses on the development of a low-fidelity aeroelastic design tool including a particular method of discretising the morphing deformation distribution over the entire wing. A distribution of local wing fold, shear, and twist is considered to create a model which can morph into any arbitrary wing shape. The model has been successfully applied to a design study of a morphing winglet of a regional airliner and a morphing outboard section of a transport aircraft wing.","morphing; aeroelasticity; conceptual design; actuation energy","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Computational Mechanics","","","",""
"uuid:9993bf69-5a8d-4b50-816e-f685185cea64","http://resolver.tudelft.nl/uuid:9993bf69-5a8d-4b50-816e-f685185cea64","Design, Analysis, Fabrication and Testing of Grid-Stiffened for Fuselage Applications","Shroff, S.","Benedictus, R. (promotor)","2014","The application of composites in aircraft structures has grown significantly in the past decade, and an increase in this growth in application has recently been achieved in fuselage designs for large civil aircraft such as the Boeing B787 and the Airbus A350. In conventional design philosophies, weight savings is the primary objective on a part-by-part basis, but, with composite constructions, the design philosophies have had to be altered and a direct replacement of a metal with a composite material may not be the most efficient design option. In the future, composite constructions for aircraft fuselage can be made frameless, or at least a reduced number of frames, while making the structure intrinsically damage tolerant owing to its design. One of the front runners in cylindrical stiffened shells for applications that undergo pressurization and therefore, in-plane bi-axial stresses, is the grid-stiffened or lattice structure. A successful application of such structures is the rocket insterstages used in Proton and Delta rockets. A primary advantage of the grid-stiffened construction is the possibility of a long uninterrupted fuselage, which leads to a simple, low-part number, and low-cost design; but the increased weight savings and reduced complexity come with a price: unknown failure modes and the difficulty of joining members to members in an airframe. These challenges are dealt with here.","grid stiffened; composite fuselage; composite joint; progressive damage","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Computational Mechanics","","","",""
"uuid:5183a61a-4263-4e70-964a-f8501f725398","http://resolver.tudelft.nl/uuid:5183a61a-4263-4e70-964a-f8501f725398","On-Line Aircraft Aerodynamic Model Identification","Laban, M.","Mulder, J.A. (promotor)","1994","","aërodynamica; vliegtuigen; databanken","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b4aee571-0489-42ff-ab55-d74e980f724a","http://resolver.tudelft.nl/uuid:b4aee571-0489-42ff-ab55-d74e980f724a","Shape Parameterization in Aircraft Design: A Novel Method, Based on B-Splines","Straathof, M.H.","Van Tooren, M.J.L. (promotor)","2012","This thesis introduces a new parameterization technique based on the Class-Shape-Transformation (CST) method. The new technique consists of an extension to the CST method in the form of a refinement function based on B-splines. This Class-Shape-Refinement-Transformation (CSRT) method has the same advantages as the original CST method, while also allowing for local deformations in a shape. A number of test cases were performed using two different design frameworks with low and high fidelity. The low fidelity framework was based on a commercial panel method code and coupled to various optimization algorithms. The high fidelity framework used an in-house Euler code and employed adjoint optimization.","shape; parameterization; aircraft; design; B-splines; Class-Shape-Refinement-Transformation; adjoint; euler; optimization","en","doctoral thesis","","","","","","","","2012-02-03","Aerospace Engineering","FPP","","","",""
"uuid:842297d4-09f6-4340-a27a-979dcfd55711","http://resolver.tudelft.nl/uuid:842297d4-09f6-4340-a27a-979dcfd55711","A decade of ERS satellite orbits and altimetry","Scharroo, R.","Wakker, K.F. (promotor)","2002","The First European Remote Sensing Satellite, ERS-1, was launched in July 1991, fol- lowed by ERS-2 in April 1995. Both satellites carry a radar altimeter to serve oper- ational applications and scientific research in the fields of geodesy, oceanography, glaciology and meteorology. Together, the satellites have now been operating for over twelve years. This thesis embarks on the a voyage along several milestones in the lifetime of these satellites, and particularly of its altimeters. Both altimeter missions were hampered by a number of misfortunes, ranging from hardware failures, via design mishaps, to a sub-optimally designed ground segment. Yet, the altimeter data, when properly processed and supplied with a precise orbit, can compete favourably with data supplied by specialised altimeter satellites like TOPEX/Poseidon and Jason-1. The upgrading of all altimeter cor- rections and the tweaking of the basic altimeter measurements of range, significant wave height and backscatter coefficient, are essential steps in this process, outlined in this thesis. Having accomplished that, the ERS altimeters allow the monitor- ing of annual, semi-annual and secular changes in sea level, which are important factors in study of climate change. A key role in the processing of altimeter data plays the position of the satellite, and its progress in time, the satellite orbit. The quality of the recovered sea surface height is limited by the precision at which the orbit can be determined. A long journey along several stepwise improvements of the orbit determination process, both in the technique as well as in the modelling, have resulted in the reduction of the orbit error by a factor of 30! A major player in this process was the estab- lishment of a gravity field model tailored to the ERS satellites that, when applied to ERS orbit determination, outperformed any of the previous and contemporary general-purpose models. Yet, it is shown that this model, DGM-E04, is not just a fabrication for the benefit of ERS only, but is equally suitable for the orbit determ- ination of TOPEX/Poseidon and as a long-wavelength geoid model. The calibration of the ERS-1 altimeter in 1991 required, at a time when the orbit errors were still counted in decimetres, if not metres, a short-arc orbit determin- ation technique centred over the calibration site off the coast of Venice. Again, through elaborate surveying, gathering of altimeter corrections and tide gauge measurements, problem solving and elimination of errors, a final absolute range bias of 41.5 cm was established, a value that is still within the error margins of more recent estimates. A timing error in the ERS altimeter data was discovered in 1995 and its cause remained a mystery ever since, especially when the timing error appeared to ex- hibit daily, annual and inter-annual variations as well. Although the exact cause may never be found, the issue is examined in fine detail and a model is constructed to eliminate the timing error for the benefit of the quality of the altimeter data.","satellite orbit determination; satellite altimetry; gravity field improvement; ERS-1; ERS-2","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9e76d4a0-2338-42e2-b949-e9bf2379cab5","http://resolver.tudelft.nl/uuid:9e76d4a0-2338-42e2-b949-e9bf2379cab5","Residual Strains in Thick Thermoplastic Composites: An Experimental Approach","Parlevliet, P.P.","Beukers, A. (promotor); Bersee, H.E.N. (promotor)","2010","Thermoplastic composites are currently investigated for application in windmill turbine blades for their recyclability. A suitable manufacturing technology for these thick structures is liquid resin infusion followed by in-situ polymerisation of Anionic Polyamide-6 (APA-6). During manufacturing of thick composite structures, temperature variations arise through the thickness, which can result in residual strains and through-the-thickness variations of properties, such as degrees of cure and crystallinity. The aim of this research was to develop experimental techniques that can be used to investigate these important effects in thick glass fibre (GF) reinforced APA-6 laminates. The used techniques comprise optic fibres with Bragg gratings, a volumetric dilatometry test based on the buoyancy principle, and the microVickers indentation test. The results as found in this research show that scaling up of GF/APA-6 composites in the thickness direction has no significant effect on the measured properties.","Thermoplastic composites; Windmill turbine; Residual stress; Residual strains","en","doctoral thesis","Technische Universiteit Delft","","","","","","","","Aerospace Engineering","Aerospace Materials and Manufacturing","","","",""
"uuid:e33139ca-e181-4c62-87dc-23e55010eac8","http://resolver.tudelft.nl/uuid:e33139ca-e181-4c62-87dc-23e55010eac8","Fatigue life prediction and strength degradation of wind turbine rotor blade composites","Nijssen, R.P.L.","Beukers, A. (promotor)","2006","Wind turbine rotor blades are subjected to a large number of highly variable loads, but life predictions are typically based on constant amplitude fatigue behaviour. Therefore, it is important to determine how service life under variable amplitude fatigue can be estimated from constant amplitude fatigue behaviour. A life prediction contains different, partly independent, elements: · the counting method, used for describing variable amplitude signals as a collection of constant amplitude cycles · formulations for describing S-N curves which relate the stresses to the number of cycles to failure · constant life diagrams which are made up of S-N curves for different stress ratios · damage rules, which relate the life expectancy of a specimen to the stress history For the description of damage, two models were investigated and compared, viz. the Miner's sum method and strength-based life prediction. In the Miner's sum method, the results of a counting method and constant amplitude fatigue behaviour description are converted into a damage parameter, ""Miner's sum"". Potential effects of load order are not taken into account. Moreover, the value of the damage parameter only indicates whether or not failure occurred: it does not relate to a physically quantifiable damage. These are limitations to the model which suspectedly might cause inaccurate predictions. In the strength-based method, life is predicted by calculating the effect of each load cycle on strength, until the load exceeds the remaining strength. An expected advantage of this cycle-by-cycle method is, that sequence effects can be implicitly included. Moreover, the damage parameter is at all times related to a physically quantifiable parameter (viz. strength). The successful application of the strength-based method requires a description of the post-fatigue strength, which entails considerable experimental effort. In addition, a strength-based life prediction is much more computationally intensive than Miner's sum and can not always utilise the same counting methods. In the comparison of the Miner's sum and the strength-based method, the influence and significance of the other life prediction elements, such as counting methods and description of constant amplitude fatigue behaviour on life prediction are included. The experimental research involved a considerable amount of material tests. The material tests give a detailed image of static strength, constant and variable amplitude fatigue behaviour (both block tests and (variants of) the WISPER spectrum were used), as well as strength degradation for different glass-fibre reinforced laminates. By selecting a single coupon geometry for all material tests on a single material, and the definition and use of standard test conditions, a consistent database was created. The block-test experiments confirm the existence of sequence effects on life, although more data are required to fully quantify them. The residual strength tests show the strength degradation after fatigue for a range of fatigue load conditions. Significant tensile strength degradation is observed in R=0.1 and R=-1 fatigue experiments. Generally, compressive strength remains within the boundaries of the initial static strength distribution. This behaviour was observed for different laminates. The significance of an adequate description of the constant amplitude behaviour is evident from the various life predictions. Commonly used simplifications, such as the Linear Goodman Diagram, result in highly non-conservative predictions. The residual strength model yields more conservative predictions than Miner's sum for the investigated tension-dominated load sequences. The experimental effort required for the determination of the strength degradation, and the computational effort do not justify this relatively small advantage. For future research, it is recommended to further improve the description of the constant life diagram. This work is focussed on fatigue of composites for wind turbine rotor blades. Nevertheless, the results are relevant for other composite structures as well.","wind engineering; laminate; composites; fatigue; strength; life; prediction; wind energy","en","doctoral thesis","Knowledge Centre WMC and DPCS group of Aerospace Engineering","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2c6046ca-40c2-4e0c-b89d-e27df00e2b8a","http://resolver.tudelft.nl/uuid:2c6046ca-40c2-4e0c-b89d-e27df00e2b8a","A real time Michelson interferometer for quantitative refractive index profile measurements: Design, validation and utilization","Nijholt, J.L.M.","Bakker, P.G. (promotor)","2004","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:23aa05e7-0762-4d13-bbe9-adccfc7e505a","http://resolver.tudelft.nl/uuid:23aa05e7-0762-4d13-bbe9-adccfc7e505a","On the scaling and unsteadiness of shock induced separation","Souverein, L.J.","Bakker, P.G. (promotor); Dussauge, J.P. (promotor)","2010","Shock wave boundary layer interactions (SWBLI) are a common phenomenon in transonic and supersonic flows. The presence of shock waves, induced by specific geometrical configurations, causes a rapid increase of the pressure, which can lead to flow separation. Examples of such interactions are found in amongst others rocket engine nozzles and on aerospikes, on re-entry vehicles, in supersonic and hypersonic engine intakes, and at the tips of compressor and turbine blades in jet engines. The interactions are important factors in vehicle development. Both the separated flow and the induced shock have been shown to be highly unsteady, causing pressure fluctuations and thermal loading. This generally leads to a degraded performance and possibly structural failure. The current work therefore aims to improve the physical understanding of the mechanisms that govern the interaction, with a special attention for the flow organisation and for the sources of the unsteadiness of the induced shock. In particular, the case of a reflecting incident shock is investigated, but the results find their application more generally in other configurations. Additionally, it is verified whether the interaction can be controlled by means of upstream fluid injection. To attain these aims, experiments were performed, comparing systematically several interactions for a range of shock intensities (producing incipiently separated and well separated flows) and under a number of flow conditions (Mach numbers of 1.7 and 2.3 and Reynolds numbers of 5,000 (‘low’) and 50,000 (‘high’)). This was done using the latest developments in the field of measurement techniques. A large amount of data was obtained for multiple interactions by means of a range of flow diagnostic techniques, yielding highly consistent results. A full field determination of the characteristic time scales by means of dual plane particle image velocimetry (Dual-PIV) has shown that the unsteadiness frequencies in the high Reynolds number incipient interaction span almost three orders of magnitude, demonstrating additionally the existence of low frequency dynamics of the reflected shock. The effect of control by means of air jet vortex generators (AJVGs) was thoroughly characterised, putting in evidence the generation of pairs of counter-rotating vortices of unequal strength that induce streaks of low and high speed fluid. These in their turn modify the separation bubble size without suppressing it. There is an inversely proportional relation between the reflected shock frequency and the bubble size. A scaling analysis was made, aimed at reconciling the observed discrepancies between interactions documented in literature. As part of this analysis, a separation criterion has been formulated that depends on the free-stream Mach number and the flow deflection angle only. In addition, a scaling approach has been derived for the interaction length based on the mass and momentum conservation. A conditional analysis has been performed based on the instantaneous separation bubble size. The generation and successive shedding of large coherent structures was found to be present also in absence of instantaneous flow separation. For the incipient cases, a link has been put into evidence between the separation region and the state of the upstream boundary layer. For the separated interactions, this link was absent and the shock unsteadiness seems to be mainly related to the separation bubble pulsation. The separation criterion in combination with the normalised interaction length represents a single trend line onto which all data for a large scope of documented interactions fall together with only a moderate scatter. This trend line predicts that the only way to effectively eliminate a separation bubble (without massive separation) by means of upstream control is by decreasing the displacement thickness of the incoming boundary layer. A scaling for the wall normal coordinate has been defined based on the interaction length with a correction for Mach number effects, producing a large resemblance in the geometric organisation of the mean and turbulent flow fields within the considered interactions. It can be concluded that multiple unsteadiness mechanisms are at work within the interaction, irrespective of the Mach number and the Reynolds number. It is proposed that the relative importance of the different mechanisms shifts with the imposed shock intensity. It seems that weak interactions without instantaneous flow separation should be governed by upstream effects only, with rather high shock frequencies. For incipient interactions, downstream effects start to occur; the region of high turbulence intensities displays mainly a lifting motion, producing a shock foot of varying strength and a shock unsteadiness that involves a time scales which can differ by at least one decade. Interactions with significant flow separation show mainly a translating motion, producing a low frequency unsteadiness and a shock foot of constant strength, which is in accordance with a free interaction behaviour. Concerning the Reynolds number and Mach number effects, it is concluded that for turbulent boundary layers, the onset of separation is Reynolds number independent. The interaction length is however governed by both the Reynolds number and the Mach number.","fluid dynamics; incident reflecting shock; compression ramp; shock wave; reflection; shock; turbulent; boundary layer; interaction; turbulence; compressible; supersonic; incipient; RSS; restricted; separation; unsteadiness; Mach; Reynolds; effect; Scaling; mass balance; control; air jet; vortex generator; PIV; Dual-PIV; time scales","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration & Operations","","","",""
"uuid:33002be1-1498-4bec-a440-4c90ec149aea","http://resolver.tudelft.nl/uuid:33002be1-1498-4bec-a440-4c90ec149aea","Thermospheric density and wind determination from satellite dynamics","Doornbos, E.N.","Ambrosius, B.A.C. (promotor)","2011","","thermosphere; CHAMP; GRACE; TLE; density; wind; orbit","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Astrodynamics and Satellite Missions","","","",""
"uuid:fa4dd59d-3792-4888-8aa5-bdb3c0d90b15","http://resolver.tudelft.nl/uuid:fa4dd59d-3792-4888-8aa5-bdb3c0d90b15","Aerospace-plane flight dynamics: Analysis of guidance and control concepts","Mooij, E.","Wakker, K.F. (promotor); Bakker, P.G. (promotor)","1998","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:21b9ea98-b9f0-4520-9460-3cfdc14601f2","http://resolver.tudelft.nl/uuid:21b9ea98-b9f0-4520-9460-3cfdc14601f2","Satellite radar interferometry: Estimation of atmospheric delay","Liu, S.","Hanssen, R.F. (promotor)","2012","","satellite radar interferometry; atmospheric delay; numerical weather model; least-squares collocation; deformation","en","doctoral thesis","Delft University of Technology","","","","","","","","Aerospace Engineering","Geoscience and Remote Control","","","",""
"uuid:ffeb73a7-2337-4ace-9ddc-f48b867adb6c","http://resolver.tudelft.nl/uuid:ffeb73a7-2337-4ace-9ddc-f48b867adb6c","Nonlinear vibrations of anisotropic cylindrical shells","Jansen, E.L.","Arbocz, J. (promotor)","2001","","buckling; nonlinear vibrations; cylindrical shells","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:bc15128e-6bfe-4992-962e-3c5f0a22ac62","http://resolver.tudelft.nl/uuid:bc15128e-6bfe-4992-962e-3c5f0a22ac62","Enhanced modelling of LAGEOS non-gravitational perturbations","Andrés de la Fuente, J.I.","Ambrosius, J.I. (promotor)","2007","","attitude dynamics; plasma physics; radiation theory; heat transfer; perturbation theory; orbit determination","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f29ecffb-04c8-4230-a1ee-9418095b628a","http://resolver.tudelft.nl/uuid:f29ecffb-04c8-4230-a1ee-9418095b628a","Forming of Laminates","De Jong, T.W.","Van Tooren, M.J.L. (promotor); Vogelesang, L.B. (promotor)","2004","Fibre-Metal-Laminates have excellent properties for aerospace applications, with GLARE as an example. The metal layers inside the laminate provide permanent plastic deformations for the whole laminate; in principle Fibre-Metal-Laminates can be formed with common sheet metal forming processes. The difference between monolithic sheet metal and Fibre-Metal-Laminates lay in the large number of failure modes for FML of which the delamination failure modes are unique for laminates. In order to predict delamination failure, the transverse shear stress distribution must be known. Different approaches to determine internal stress distribution of the laminate, on an analytical base, are compared with each other and with experimental results. The analytical model that was developed in this research is implemented into a stand alone software package to act as a design tool.","glare; fml; formability; interlaminar shear","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7ab34006-2323-4779-8ea9-b08e0e43f213","http://resolver.tudelft.nl/uuid:7ab34006-2323-4779-8ea9-b08e0e43f213","Optimization of microstructure and properties of high strength spring steel","Choi, S.","Van der Zwaag, S. (promotor)","2011","This thesis describes a research project on the development of a new grade of low cost spring steel with exceptional mechanical properties on the basis of a complete understanding and quantification of the metallurgical processes taking place during the various stages of the heat treatment. The new composition in combination with a new 2-step tempering treatment resulted in a steel with a tensile strength in excess of 2400 MPa and a reduction of area for quasi-static tensile fracture of more than 20%.","alloy design; quenching and tempering; spring steel; ultra high strength; reduction of area; precipitation behavior; step tempering; dilatation; modeling; decarburization; oxidation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Novel Aerospace Materials","","","",""
"uuid:034ea886-d494-4c28-a35f-316717f466c9","http://resolver.tudelft.nl/uuid:034ea886-d494-4c28-a35f-316717f466c9","Sea-Level Data Assimilation for Estimating Salinity Variability in the Tropical Pacific","Vossepoel, F.C.","Wakker, K.F. (promotor); de Ruijter, W.P.M. (promotor)","1999","","","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:25070509-2292-42ed-8ba9-bf070fdbb793","http://resolver.tudelft.nl/uuid:25070509-2292-42ed-8ba9-bf070fdbb793","GNSS Carrier Phase-based Attitude Determination: Estimation and Applications","Giorgi, G.","Teunissen, P.J.G. (promotor)","2011","Attitude determination through the use of Global Navigation Satellite System (GNSS) signals is one of the many applications of satellite-based navigation. Multiple GNSS antennas installed on a given platform are used to provide orientation estimates, thus adding attitude information to the standard positioning service. Precise attitude estimates are obtained by exploiting the higher ranging resolution of the carrier phase observables, which are of two orders of magnitude more accurate than pseudorange measurements. However, each carrier phase measurement is ambiguous by an unknown integer number of cycles. Carrier phase integer ambiguity resolution is the key to high-precision GNSS positioning, navigation, and attitude determination. It is the process of resolving the unknown cycle ambiguities of the carrier phase data as integers. After ambiguity resolution, precise baseline estimates become available, which can be used to derive the attitude of a platform equipped with multiple antennas. The purpose of this contribution is to present, analyze and test a novel ambiguity estimation and attitude determination method. The ambiguity-attitude estimation method given and analyzed in this work is an implementation of the constrained integer-least quares, an extension of the well-known least-squares method applied to systems whose parameters are subject to mixed constraints. The key to this new method is an extension of the popular LAMBDA method: the multivariate constrained LAMBDA method. The method estimates the integer ambiguities and the platforms attitude in an integral manner, fully exploiting the known body geometry of the multi-antenna configuration by means of multiple geometrical constraints. As a result, the ambiguity resolution performance is greatly improved, and the reliability of the GNSS-based attitude solution is enhanced. The method is extensively analyzed from a theoretical standpoint, and thoroughly tested with a wide range of test scenarios, from simulations to high-dynamic flight experiments.","GNSS; GPS; Attitude; Compass; Attitude determination; Ambiguity resolution","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Delft Institute of Earth Observation and Space Systems","","","",""
"uuid:3e46f5b1-1887-4c7c-9d5e-9a6a56126ebf","http://resolver.tudelft.nl/uuid:3e46f5b1-1887-4c7c-9d5e-9a6a56126ebf","Megathrust Earthquakes: Study of Fault Slip and Stress Relaxation Using Satellite Gravity Observations","Broerse, D.B.T.","Ambrosius, B.A.C. (promotor)","2014","During earthquakes large scale mass displacements take place when slip on a fault deforms the earth’s crust. Besides, in the days to decades after the main shock ongoing deformation is usually observed that is related to relaxation of stresses caused by the earthquake. In this thesis I relate gravity changes as observed by the GRACE satellite mission to solid earth deformation caused by earthquakes. Special attention is given to modeling the contribution of ocean mass redistribution to gravity changes, and its relation to changes in bathymetry. I show that common modeling practices are usually not properly taking into account the effect of ocean water redistribution when computing seismic gravity changes. Using a combination of GRACE data and GPS observations I interpret ongoing gravity changes and crustal motions after the 2004 Sumatra-Andaman earthquake as dominantly caused by viscoelastic mantle flow. Contrasts in relaxation styles from both observation types are related to lateral variations in mantle rheology below the subduction zone. The combined analysis of GPS and GRACE data strongly suggest that the mantle at the continental side of the subduction zone is weaker than the oceanic side.","earthquakes; time-variable gravity; GRACE; sea level change; viscoelastic relaxation; megathrusts; GPS; 2004 Sumatra-Andaman earthquake; 2010 Maule earthquake; 2011 Tohoku earthquake; normal modes; burgers rheology; mantle rheology","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Astrodynamics and Satellite Missions","","","",""
"uuid:fda3beda-4f43-4055-9e61-78610bfd14cb","http://resolver.tudelft.nl/uuid:fda3beda-4f43-4055-9e61-78610bfd14cb","Scenarios for offshore wind development in the Netherlands: An agent-based modelling approach","Mast, E.H.M.","Van Bussel, G.J.W. (promotor); Künneke, R.W. (promotor)","2014","The aim of this study is to develop a method to identify the barriers to and opportunities in the development of large-scale offshore wind energy in the Netherlands, taking into account the uncertainties of the future and consequences of decisions, from technological, economical, social, political and environmental perspectives. The research question is stated as: can an agent-based model be used to develop realistic implementation paths towards 6000 MW installed offshore wind power in the Dutch EEZ that show the consequences for the stakeholders? The focus topics for the model are the permit procedures, financial support, layout and timing of an offshore grid, the availability of resources, and innovation, especially of wind turbines. The results show that the agent-based model can indeed simulate different implementation paths that can be used for policy and decision support as a communication tool to show different possible futures and the limiting factors for the implementation in these futures. The methodology given in this study provides a step plan to develop such an agent-based model in analysis, design, implementation and validation phases. The main disadvantages of using agent-based modelling are: the extensive (detailed) data gathering, a long development time dependent on the implementation process and available standards, the required 'mass' and development time before simulations can be made that can be validated, and the limitations in modelling complex actor behaviour. The main advantages of using agent-based modelling are: the model can combine technological and socio-institutional aspects, the model can combine qualitative and quantitative data, the agent-based `as-is' modelling makes design easier, the model is easily extendable and a computer model is transparent.","offshore wind; agent-based; social simulation; wind energy","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","","",""
"uuid:36eb2384-b5a2-4883-b7f7-75d008816482","http://resolver.tudelft.nl/uuid:36eb2384-b5a2-4883-b7f7-75d008816482","Design tailoring of panels for pressure pillowing using tow-placed steered fibers","Alhaj Ahmad, A.","Gürdal, Z. (promotor)","2008","","variable-stiffness; pressure pillowing; tow-placed fibers; structural optimization","en","doctoral thesis","TU Delft, Faculteit Luchtvaart- en Ruimtevaarttechniek","","","","","","","","Aerospace Engineering","","","","",""
"uuid:129c631c-efdc-4b3f-b94d-41777d21d51e","http://resolver.tudelft.nl/uuid:129c631c-efdc-4b3f-b94d-41777d21d51e","Knowledge based engineering support for aircraft component design","Van der Laan, A.H.","Van Tooren, M.J.L. (promotor)","2008","","kbe; cost engineering","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0de8efcb-1c1c-4a16-8014-c27c64eb3dd1","http://resolver.tudelft.nl/uuid:0de8efcb-1c1c-4a16-8014-c27c64eb3dd1","A System for the Acquisition and Analysis of Image Sequences to Model Longitudinal Driving Behavior","Karimi Nejadasl, F.","Menenti, M. (promotor); Hoogendoorn, S.P. (promotor)","2010","Traffic causes important problems in many societies. Considerable amounts of energy, money and time are wasted in traffic jams and even more important are car accidents and casualties in traffic (more than 40,000 deaths per year in the USA (Hitti (2005)) and 791 deaths in 2007 in the Netherlands (van Verkeer en Waterstaat (2008))). To alleviate the problems, traffic is continuously and intensively controlled and studied by authorities and researchers. The results of ongoing research on traffic lead to the development of new infrastructure facilities and rules. The behavior of drivers in different traffic situations, however, is still not sufficiently known. The driving behavior consists in the reaction of a driver to the action of surrounding vehicles. The stimuli can be the distance of the follower from the leader and the speed of the follower and leaders when the leaders change their behavior such as in changing lane and braking. As a result, the response of the follower to these actions may be predictable with stimuli-response models. This can be used, for example, to regulate traffic by advising a safe distance which the driver should keep when leading vehicles change their behavior. The findings on the driving dynamics can be used in dynamic traffic management and in advanced driver assistance systems such as adaptive cruise control. Dynamic traffic management controls the efficient use of infrastructure and predicts the effect of future changes on the infrastructure. Thus it allows more effective management and providing better traffic information such as in ramp metering, incident management, travel information (travel time, route recommendation). To get insight into drivers' behavior, it is, therefore, indispensable to reconstruct extended trajectories of observed vehicles for a long stretch of a freeway for a long time at high frequency under the same or nearly the same conditions, while satisfying positioning and speed accuracy requirements. Current systems for measuring the trajectories of each individual vehicle at any time are not sufficiently mature. This thesis describes a system which was designed and implemented for the collection of many long and detailed vehicle trajectories with the same or nearly the same conditions of weather, traffic, road and surroundings to improve stimuli-response models (longitudinal driving behavior). We evaluated possible platforms and sensors and a helicopter was chosen due to its widespread use for many applications, its flexibility and hovering properties. A camera with the resolution 1392x1040 and frame rate 15 was selected to record a sequence of images. The image sequence contains locations of vehicles as a function of time. We established that for our purpose the helicopter should hover over a freeway while looking in a nadir direction, with the camera mounted horizontally below the helicopter. The helicopter height is the main platform parameter affecting the characteristics of the recorded data: The increasing height implies to observe a longer stretch of a road is observed at higher flight altitude, but at the price of a larger ground sampling distance (GSD) value. For the camera the combination of CCD elements and the field of view (FOV) determines the GSD at a given height. A larger frame rate provides more details about vehicle trajectories. The system configuration, i.e. the set of camera and platform parameters, is determined taking also into account the ground slope and meet the given requirements. The proposed system acquires image sequences from a helicopter hovering over freeways. These image sequences contain both camera and vehicle motion. The vehicle motion is, therefore, contaminated by the camera motion. Current methods to remove the camera motion from an entire image sequence, i.e. performing image-sequence stabilization, require the determination of the scene position, which is a complicated and computationally expensive task. We therefore decided to develop a new procedure to stabilize the entire image sequence. We investigated in which cases corresponding pixels projected from a scene object to images in a sequence are related by the camera motion only without requiring the scene position. This relation is a so-called projective or homography. As a result, the relation between corresponding fixed points of two consecutive images and corresponding road area points in any two images is expressed by a homography. By knowing this homography, every given point in one image is transformed to the corresponding point in the other image. Only few reliable corresponding points are needed to establish each homography relation. Because of having a very large number of images from different areas, the automatic and robust extraction of corresponding points is required. The difficulties in finding correspondences are due to having pixels of moving objects, changing illumination conditions, image noise, existence of repeated patterns, scene elements with sparse structure, a large transformation which changes the perspective and scene occlusions. The robust registration methods are, therefore, investigated, designed and developed to handle these difficulties. Two different groups of methods were investigated for automatic and robust registration of two consecutive images. These methods were feature based and featureless. Two feature-based methods are introduced: KLT-RANSAC and SIFT-RANSAC with the difference being the procedure to find corresponding points between two consecutive images. In KLT, points are first extracted in one image and then tracked in the second image. In SIFT, the points are extracted from both images and then they are connected. These corresponding points are used to estimate parameters of the homography model between two consecutive images by RANSAC, which is a robust parameter estimator. In the featureless method, a DE-based registration procedure is designed and developed. Without explicitly extracting any corresponding points, this method uses all the image pixels. Parameters of the homography model between two consecutive images are obtained by minimizing the difference between one image and the transformed second image. We found out that the registration of the consecutive images is robust by any of the registration methods that we used. In contrast, the registration of the arbitrary images in the whole image area or only on the road area is not robust due to having a large number of wrong corresponding points. Consequently, a new framework was designed to stabilize the image sequence on the road area. This framework includes two steps: registration of two consecutive images and stabilization of the entire image sequence of the road area. After registration of two consecutive images, the registration of the entire sequence of images of the road area is done. The homography between two consecutive images is taken equal to the homography corresponding to the road surface. A product of this homography and the homography corresponding to the road surface between the previous image and a reference image (here the first image in the sequence), provides another homography, which registers the current image to the reference image on the road area. Such registration contains errors from both described homographies. As a result, the road areas are registered approximately due to small errors in the two homographies. By identifying the points in the road area of the reference image only, these points are matched in the transformed current image just around a very small search area. These corresponding points are used to calculate the homography parameters between the reference image and the transformed current image. The product of this homography by the approximate homography gives the homography corresponding to the road area of the current image and reference image. The same procedure is applied iteratively to the entire sequence. As a result, the road area in image sequence is registered. The image sequence is stabilized on the road area in an automatic, robust and reliable way, independently of differences in image content, traffic and environmental conditions. Besides, the new framework provides an error free sequential registration, without requiring computationally expensive bundle adjustment. The procedure is fast as well. No assumption is made on the camera motion or on the scene. After removing the camera motion from the entire sequence, vehicles are identified and tracked. The vehicles were identified by first distinguishing between background and vehicle pixel for each image by analyzing the gray-level temporal profile of each pixel. Background pixels are assumed to be discriminated by the higher frequency in a gray-level histogram. After identifying the vehicle and background pixels, clusters of vehicle pixels are grouped and indicated as a ""blob"". A blob and each pixel of it are then tracked using the optical flow method. These displacements are contaminated by errors which are removed by analyzing the histogram of the displacements. From the histogram, the most frequent value corresponds to the real vehicle displacement, which is the same for all pixels of a vehicle (a rigid object). The positions of the vehicles are updated after tracking them. The vehicles are identified in each image to detect new vehicles and update the boundaries of all vehicles. The vehicle extraction method detects many similar vehicles which contain only few details and with different motion, particularly vehicles having low speed and low contrast. Both vehicle extraction and tracking methods are sequential and only require very small amount of memory. The results are reliable due to the temporal connectivity in the vehicle extraction and spatio-temporal connectivity in the tracking method. Trajectories obtained with the system described above can be used to get insights into drivers' behavior towards improved predictive models. The system can be used for dynamic traffic management using the real time trajectory extraction by a hardware implementation of the procedure. If the real time extraction of trajectories is not an issue, trajectories can be improved by analyzing them and then give a feed back to the vehicle identification system. Integration of the results from spatio-temporal analysis can further improve the identification system.","traffic monitoring; image sequence stabilization; image sequence registration; background and foreground identification; vehicle detection; vehicle tracking","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:bc7f8919-1baf-4f02-b115-dc926c5ec090","http://resolver.tudelft.nl/uuid:bc7f8919-1baf-4f02-b115-dc926c5ec090","Least-squares variance component estimation: Theory and GPS applications","Amiri-Simkooei, A.","Teunissen, P.J.G. (promotor)","2007","In this thesis we study the method of least-squares variance component estimation (LS-VCE) and elaborate on theoretical and practical aspects of the method. We show that LS-VCE is a simple, flexible, and attractive VCE-method. The LS-VCE method is simple because it is based on the well-known principle of least-squares. With this method the estimation of the (co)variance components is based on a linear model of observation equations. The method is flexible since it works with a user-defined weight matrix. Different weight matrix classes can be defined which all automatically lead to unbiased estimators of (co)variance components. LS-VCE is attractive since it allows one to apply the existing body of knowledge of least-squares theory to the problem of (co)variance component estimation. With this method, one can 1) obtain measures of discrepancies in the stochastic model, 2) determine the covariance matrix of the (co)variance components, 3) obtain the minimum variance estimator of (co)variance components by choosing the weight matrix as the inverse of the covariance matrix, 4) take the a-priori information on the (co)variance component into account, 5) solve for a nonlinear (co)variance component model, 6) apply the idea of robust estimation to (co)variance components, 7) evaluate the estimability of the (co)variance components, and 8) avoid the problem of obtaining negative variance components.","least-squares variance component estimation (ls-vce); normal distribution; elliptically contoured distribution; minque; bique; reml","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:dc3af055-f75f-4a1f-a4f5-062a273ba954","http://resolver.tudelft.nl/uuid:dc3af055-f75f-4a1f-a4f5-062a273ba954","Performance Evaluation of Polybenzimidazole for Potential Aerospace Applications","Iqbal, H.M.S.","Benedictus, R. (promotor); Bhowmik, S. (promotor)","2014","With the increasing use of polymer based composite materials, there is an increasing demand of polymeric resins with high glass transition temperature, high thermal stability and excellent mechanical properties at high temperature. Polybenzimidazole (PBI) is a recently emerged high performance polymer. It has the highest glass transition temperature of any commercially available organic polymer, high decomposition temperature, good oxidation resistance and it maintains excellent strength at cryogenic temperatures. Due to its excellent thermal and mechanical properties, PBI has great potential to be used for many high temperature applications. The present work has contributed to the knowledge and understanding of several aspects of the PBI polymer. Different problems related to the processing of unfilled and carbon nano-fibers reinforced PBI in the form of film, coating and adhesive are highlighted. Performance of PBI after exposure to various environmental conditions is evaluated. PBI has shown great potential to be used as fire resistant coating in aircraft. It also has revealed its potential to be used for different space applications.","Polybenzimidazole; Carbon Nanofibers; Fire Testing; Radiation testing; Polybenzimidazole Adhesive; Polybenzimidazole Coating","en","doctoral thesis","","","","","","","","2014-01-14","Aerospace Engineering","Structure Integrity and Composite group","","","",""
"uuid:1bf5f5b6-95da-4d70-84f9-571cdabb5b0d","http://resolver.tudelft.nl/uuid:1bf5f5b6-95da-4d70-84f9-571cdabb5b0d","Biophysics in aircraft control: A model of the neuromuscular system of the pilot's arm","Van Paassen, M.M.","Gerlach, O.H. (promotor); Stassen, H.G. (promotor)","1994","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4ff21247-fdbd-472d-88b9-59bf3abfd392","http://resolver.tudelft.nl/uuid:4ff21247-fdbd-472d-88b9-59bf3abfd392","Applications of the Cellular Automata Paradigm in Structural Analysis and Design","Abdalla, M.M.","Guerdal, Z. (promotor)","2004","Recent is een techniek ontstaan voor de aanpak van gecombineerde automatische analyse en ontwerp van een- of meerdimensionale elastische systemen in een omgeving van meervoudig parallel rekenen. De aanpak is gebaseerd op het paradigma van âcellular automata (CA)â. De implementatie van deze techniek voor het ontwerpen van constructies is in zekere mate een poging tot het simultaan bepalen van de toestands- en ontwerpvariabelen via sterk niet-lineaire differentiaalvergelijkingen die het system beschrijven, alsmede van de daarbij behorende optimaliteitsvoorwaarden, De grootste voordelen van CA voor constructief optimaliseren zijn 1) zijn potentie voor implementatie van massief parallel gebruikte geavanceerde hardware, 2) de lokale aanpak van zowel de analyse als het ontwerp, en 3) zijn vanzelfsprekende geschiktheid voor een simultane aanpak via optimaliseringtechnieken van zowel het veldprobleem als het ontwerp. Als onderdeel van het onderzoekproject werd een algorithme voor door eigenwaardeberekening bepaalde aspecten in het ontwerpen van constructies gepresenteerd. Voor het begrip was dit een belangrijk onderzoeksgebied, omdat de lokale aard van CA algorithmen op zijn minst schijnbaar wordt beınvloed door de globale aard van de eigenwaarde response. Het voorgestelde algorithme werd zo ontworpen dat het volledig lokaal was van aard en dus bruikbaar voor CA type implementatie. Het algorithme werd toegepast op het ontwerp van kolommen met weerstand tegen Euler- Bernouilli knik. De analyse beschrijving die werd gebruikt voor een eerste schatting van de verplaatsing, werd bepaald met energie-principes. De CA analyse gecombineerd met ontwerp-algorithmen heeft bewezen een efficiente en nauwkeurige voorspelling te geven van optimale kolomvormen en de bijbehorende knikpatronen. Vervolgens is een op CA gebaseerd topologisch ontwerp-algorithme gepresenteerd, waarbij de ontwerp-regels voor een qua stijfheid optimaal ontwerp van een tweedimensionale lineair elastische continuum topologie, is ontwikkeld met gebruik van variatierekening. De CA ontwerp-regel is gebaseerd op de continue optimaliserings criteria, ge¨ınterpreteerd als lokale Kuhn-Tucker condities. De CA analyse regel was, zoals bij het eigenwaarde-ontwerp probleem, gebaseerd op minimalisering van de energie. Numerieke experimenten met het voorgestelde algorithme gaven een aanwijzing dat de CA ontwerp regel zeer robuust is en niet leidt aan âschaakbordâ- achtige patronen in de materiaal verdeling, noch aan numerieke instabiliteit. Met het gegeven van de eenvoud van het CA algorithme werd duidelijk, dat CA een veelbelovende methodiek is voor topologisch optimaal ontwerpen. Topologische optimalisering met betrekking tot minimum vervormbaarheid van een constructie vereist een gedetailleerd CA raster om de topologische kenmerken voldoende te beschrijven. In dit verband werd geconstateerd dat de CA analyse slechts langzaam convergeerde. De met toenemende raster-dichtheid slechter wordende CA convergentie kon worden verwacht op grond van het feit, dat CA geheel vertrouwt op informatie-uitwisseling op lokaal niveau. In een hypothetisch ideale CA machine waar alle cellen gelijktijdig snel worden aangepast zou dit geen probleem zijn. Dan zou de efficiency van CA nog altijd aanzienlijk zijn door de eenvoud van de elementen. Aan de andere kant zou een dergelijke afnemende convergentiegraad een significante beperkende factor betekenen, indien gebruik wordt gemaakt van de bestaande seri¨ele processoren. Na het succes met CA voor ontwerp regels in topologisch optimalisering, werd besloten zulke regels voor niet-lineaire problemen met âlimit pointâ gedrag en gebruik van strikte optimaliteits condities, af te leiden. De ontwerpregel werd met succes geformuleerd als een probleem op locaal, cel niveau. De ontwerpregel werd gekoppeld aan niet-lineaire Eindige Elementen Analyse voor het bepalen van de optimale vorm van een MEMS balkje op micro-schaal. De convergentie van de CA ontwerpregel bleek zeer snel en had slechts tussen de 20 en 30 EE analyses nodig. De resultaten bevestigden dat lokale regels voor een optimaal ontwerp behoorlijk presteren en inderdaad kunnen worden beschouwd als een algemene methode om CA-ontwerp regels af te leiden. De mechanische response van een MEMS microbalkje is niet-lineair van aard vanwege de niet-lineaire relatie tussen elektrostatische belasting en de doorbuiging van het balkje. Er is sprake van limit-point (pull-in) gedrag. We beschouwden de optimalisering van de vorm van een capacitieve microbalk voor maximaal intrek voltage. Uitvoerige resultaten werden gegenereerd voor verschillende randvoorwaarden. De optimaliseringresultaten gaven aan, dat een substantile vergroting van het intrek-voltage kon worden bereikt door de breedteen dikteverdeling te varieren. De implementatie van CA als een gecombineerd analyse- en ontwerpgereedschap, waarin zowel CA analyse regels als CA ontwerp regels worden toegepast, kan worden beschouwd als te zijn gebouwd op algorithmes. De methodiek leidt uiteindelijk tot het verkrijgen van een geconvergeerd optimaal ontwerp. Een combinatie van minimalisering van de energie voor de afleiding van de analyse regels en de eis van optimaliteit voor het bepalen van de ontwerp regels, is algemeen toepasbaar op een breed gebied van constructieve problemen. De grootste uitdagingen liggen in het bedenken van bruikbare hardware- en software-implementaties waar de typische rekenkundige voordelen van CA, voortkomend uit het massief parallelle karakter, duidelijk kunnen worden aangetoond.","cellular automata; structural optimization; topology design","en","doctoral thesis","DUP Science","","","","","","","","Aerospace Engineering","","","","",""
"uuid:22260eb9-ec7c-408f-9050-d7e7dc0c28f1","http://resolver.tudelft.nl/uuid:22260eb9-ec7c-408f-9050-d7e7dc0c28f1","Stress analysis of structural bonded joints","Gleich, D.M.","Van Tooren, M.J.L. (promotor); Beukers, A. (promotor); De Jong, Th. (promotor)","2002","","adhesive; stress analysis; bondline thickness","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8d7b75cd-6673-4dd5-8b98-b64193633062","http://resolver.tudelft.nl/uuid:8d7b75cd-6673-4dd5-8b98-b64193633062","The Kinematic design of flight simulator motion bases","Advani, S.K.","Mulder, J.A. (promotor); Bosgra, O.H. (promotor)","1998","","flight simulator; motion-bases; mechanism; human factors; vehicle simulation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:19037c4d-d787-4cab-a182-6fcc33badf70","http://resolver.tudelft.nl/uuid:19037c4d-d787-4cab-a182-6fcc33badf70","A Koiter-Newton arclength method for buckling-sensitive structures","Liang, K.","Gürdal, Z. (promotor)","2013","Thin-walled structures, when properly designed, possess a high strength-to-weight and stiffness-to-weight ratio, and therefore are used as the primary components in some weight critical structural applications, such as aerospace and marine engineering. These structures are prone to be limited in their load carrying capability by buckling, while staying in the linear elastic range of the material. Buckling of thinwalled structures is an inherently nonlinear phenomena. When the material stays within its linear elastic range, the source of the nonlinearity is purely geometric. Thus, the analysis of nonlinear response of structures, especially thin-walled structures which are buckling sensitive, is important for determining their load carrying capability. For this reason, structural geometric nonlinearities are increasingly taken into account in engineering design. Nowadays, with the expanding computational power of modern computers nonlinear finite element analysis using commercial software is becoming the standard technique used to obtain the nonlinear response of complex structures, however, the repeated analyses that are needed in the design phase are still computationally intensive, in terms of the computation time required to run large models, even for modern computers. For this reason, reduced order techniques that reduce the problem size are attractive whenever repetitive analyses are required, such as in design optimization. Research on reduced order modeling of the nonlinear response of structures has attracted much attention from researchers. Some analytic techniques constitute very powerful tools for reducing the number of degrees of freedom (DOFs) in a nonlinear system, such as the Rayleigh-Ritz techniques and perturbation techniques. These two reduced basis techniques can be implemented in both analytical and numerical contexts, and due to the modeling versatility of the finite element method (FEM), most researchers prefer to reconstruct them within the FEM context, referred to as reduction methods. There are two families of reduction methods which can be recognized. The first family consists the path-following reduction methods which are based on some analytic techniques to reduce the number of DOFs in the full model and are able to trace the entire nonlinear equilibrium path of structures automatically, while they may find difficulties in the presence of buckling. Koiter reduction methods belong to the second family, and they are very good at handling the buckling sensitive cases due to the use of Koiter’s classical initial postbuckling theory, but the Koiter perturbation approach also limits the validity of these methods to a small range around the bifurcation point. The focus of the research reported in this thesis therefore is to find ways to synthesize the advantages of current reduction methods and obtain a new reduced basis path-following approach. In this thesis, a new approach called the Koiter-Newton (K-N) is presented for the numerical solution of a class of elastic nonlinear structural analysis problems. The method combines ideas from Koiter’s initial post-buckling analysis and Newton arclength methods to obtain an algorithm that is accurate over the entire equilibrium path of structures and efficient in the presence of buckling and/or imperfection sensitivity. The proposed approach is performed in a step by step manner to trace the entire equilibrium path, as is commonly used in the classical Newton arc-length method. In every expansion step, the approach works by combining a prediction step using a nonlinear reduced order model (ROM) based on Koiter’s initial postbuckling expansion with a Newton arc-length correction procedure. This nonlinear prediction provided by the reduced order model is much better compared to linear predictors used by the classical Newton-Raphson method, thus allowing the algorithm to use fairly large step sizes. The basic premise behind the proposed approach is the use of Koiter’s asymptotic expansion from the beginning rather than using it only at the bifurcation point in contrast to the traditional Koiter approaches. In each asymptotic expansion, the force space is reduced by the span of a set of perturbation loads that are chosen to excite the possible buckling branches. According to the stability of the equilibrium point, at which the asymptotic expansion is applied, different ways for selecting the perturbation loads are proposed. The proposed selection rules guarantee that the expansion step of the proposed approach can be applied at any point along the equilibrium path. The proposed technique requires derivatives of the element load vectors with respect to the degrees of freedom up to the third order. This is two orders more than what is traditionally needed for Newton’s method. To facilitate differentiation, nonlinear elements based on the element independent co-rotational frame are applied in the Koiter-Newton analysis. Automatic differentiation is used to find the derivatives of the co-rotational frame with respect to element degrees of freedom. In this way, full nonlinear kinematics are taken into account when constructing the reduced order model. In some cases, the nonlinear in-plane rotations of structures can be neglected, although the rotations of the normals to the mid-surface are finite. In such cases, Von Karman kinematics, which ignore some nonlinear items in the Green’s staindisplacement relations, possess an acceptable accuracy compared with the full nonlinear kinematics. Hence, the Koiter-Newton approach is also implemented based on Von Karman kinematics to achieve a better computational efficiency. Various numerical examples of beam and shell models are presented and used to evaluate the performance of the method. The Koiter-Newton analyses using the corotational kinematics and the Von K´arm´an kinematics are accurate and more computational efficient, compared with the results obtained using ABAQUS which adopts a full nonlinear analysis. The improved efficiency demonstrated by the Koiter-Newton technique will open the door to the direct use of detailed nonlinear finite element models in the design optimization of next generation flight and launch vehicles.","buckling; imperfection; geometric nonlinearity; path-following; Koiter-Newton approach; reduced order model; finite elements","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Computational Mechanics","","","",""
"uuid:3df42a90-aca3-4247-8376-ae9a31ec3def","http://resolver.tudelft.nl/uuid:3df42a90-aca3-4247-8376-ae9a31ec3def","Robust flight control: Several aeronautical applications","Bennani, S.","Mulder, J.A. (promotor)","2002","","Robust control; mu-synthesis; lineair parameter varying system control; gain scheduling; flight control systems","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:83466092-f531-41e2-8ef3-5985b608aeac","http://resolver.tudelft.nl/uuid:83466092-f531-41e2-8ef3-5985b608aeac","Automatic reconstruction of industrial installations: Using point clouds and images","Rabbani Shah, T.","Vosselman, M.G. (promotor)","2006","","","en","doctoral thesis","Nederlandse Commissie voor Geodesie","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8de687c6-61da-410d-9550-5a72b020c07c","http://resolver.tudelft.nl/uuid:8de687c6-61da-410d-9550-5a72b020c07c","Haptic Interface for UAV Teleoperation","Lam, T.M.","Mulder, J.A. (promotor); Van der Helm, F.C.T. (promotor); Mulder, M. (promotor)","2009","In the teleoperation of an uninhabited aerial vehicle (UAV), the human operator is physically separated from the vehicle and lacks various multiple-sensory information such as sound, motions, and vibrations of the airframe. The operator is usually only provided with visual information, e.g., from camera images with limited resolution and field of view. All this leads to lower situation awareness, which in turn leads to reduced safety in teleoperation and high operator workload. The goal of this thesis is to increase the safety of UAV teleoperation and reduce operator workload. The approach taken is to apply haptic feedback, i.e., provide information regarding the UAV motion relative to the environmental constraints through the sense of forces on the control device. The research approach consists of the development of an artificial force field that maps environmental constraints to virtual forces that can be used for haptic feedback to the operator. Different implementations of haptic feedback is investigated. The virtual forces can be presented as external forces on the haptic control device (force feedback), as an increase in the spring constant of the control device (stiffness feedback), or a combination of both techniques (force-stiffness feedback). Additionally, effects of signal transmission time delays due to, for example, a satellite communication is investigated and a method, the so-called wave variable transformation, is provided to reduce the negative effects of time delays. Finally, a model of the neuromuscular system of the human arm is used in offline simulations for tuning of the haptic feedback. From the findings in this thesis, it can be concluded that, generally, the use of haptic feedback significantly increases the level of safety, at the cost, however, of higher operator physical control effort. When operators are more aware of the safety-benefit with haptic feedback, then they are willing to accept this higher physical load and the overall subjective workload will not increase. When time delays are present, haptic feedback can maintain the high level of safety using wave variables. Force-stiffness feedback has the potential to further increase the level of safety without higher operator workload levels, and it can therefore be considered to be the main candidate to further improve haptic feedback in UAV teleoperation. Finally, in an early stage of haptic feedback design it is not necessary to use a model of the neuromuscular system. However, for tuning and further optimization a neuromuscular model is an important tool.","Haptic feedback; UAV; wave variables transformation; neuromuscular system; collision avoidance system; artificial force field; force feedback; stiffness feedback; force-stiffness feedback; unmanned aerial vehicle; uninhabited aerial vehicle","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:b969b96a-3d91-48f8-8b08-199899046746","http://resolver.tudelft.nl/uuid:b969b96a-3d91-48f8-8b08-199899046746","Multilevel design optimization of composite structures with blended laminates","Seresta, O.","GÜrdal, Z. (promotor)","2007","This research work deals with the design and optimization of a large composite structure. In design of large structural systems, it is customary to divide the problem into many smaller independent/semi-independent local design problems. The use of composite necessitates the inclusion of ply angles as design variables. These design variables are discrete in nature because of manufacturing constraint, which directly affect the lay up cost. The multilevel approach results into a nonblended solution with no continuity of laminate layups across the panels. In this work, we develop a global local design methodology to design blended composite laminates across the whole structural system. The blending constraint is imposed via a guide based approach within the genetic algorithm optimization scheme. In an effort to include the postbuckling constraint into the multilevel design optimization of large composite structure, an alternative cheap methodology for predicting load paths in postbuckled structure is presented.","composites; discrete optimization; genetic algorithms; global-local methodology; buckling; postbuckling; blending","en","doctoral thesis","TU Delft, Faculteit Luchtvaart- en Ruimtevaarttechniek","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6346e50f-32da-4e6f-9f91-daa5167971e5","http://resolver.tudelft.nl/uuid:6346e50f-32da-4e6f-9f91-daa5167971e5","Genetic Design of Ultra High Strength Stainless Steels: Modelling and Experiments","Xu, W.","Van der Zwaag, S. (promotor)","2009","","alloy design; ultra high strength; stainless; maraging; precipitate strengthening steels; genetic algorithm; thermodynamics","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures and Materials","","","",""
"uuid:8925fc2a-47e8-457a-960c-f86b5065fa60","http://resolver.tudelft.nl/uuid:8925fc2a-47e8-457a-960c-f86b5065fa60","Fatigue Crack Growth Prediction for generalized fiber metal laminates and hybrid materials","Wilson, G.S.","Benedictus, R. (promotor)","2013","The excellent durability performance of Glare, a thin fiber metal laminate (FML) material system, is now being proven in service. This has motivated work towards the application of FMLs to thicker structures driven by damage tolerance. In order to fully characterize the crack growth life of such materials, models are necessary that can account for the unique aspects of material systems under consideration, including non-uniformity of composition and stress states, and the resulting complex damage state involved in fatigue crack growth. This thesis presents a generalized analytical model for the prediction of fatigue crack and delamination growth in FMLs of arbitrary lay-up, including differing metal alloys, different thickness layers, and different combinations of reinforcing composite layers. Cracks in each layer, and delaminations in each interface, are allowed to grow separately, with the interactions of the damage throughout the laminate taken into account. The model is structured in a modular and iterative fashion. Modules for determining the load redistribution around damage and the strain energy release rate of delamination have been derived and independently validated through comparison to finite element analyses. A series of tests with thick fiber metal laminates of varied construction was carried out to verify the overall crack growth predictions of the model. While some discrepancies between the results and predictions for the most complex laminates suggest that refinement of the delamination strain energy release rate formulation is needed, many of the test results were accurately predicted, demonstrating the suitability of this model for use in design and analysis of thick FML structures.","FML; Fatigue Crack Growth; fracture mechanics","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Structural Integrity","","","",""
"uuid:45ed17b3-4743-4adc-bd65-65dd203e4a09","http://resolver.tudelft.nl/uuid:45ed17b3-4743-4adc-bd65-65dd203e4a09","Knowledge based engineering techniques to support aircraft design and optimization","La Rocca, G.","Van Tooren, M.J.L. (promotor)","2011","Since the 1960s, the demand for air transportation has doubled every 15 years, resilient to every oil crises and international events. However, the current capability of the air transport management system, the demand of increasingly growing levels of quality, comfort, safety and security, and, above all, an environmental sensitivity as high as never before, seem to constrain any further growth. The Advisory Council for Aeronautical Research in Europe (ACARE), similarly to NASA in the United States, has indicated a set of challenging objectives and devised a roadmap to help the aerospace industry stepping into a new age of sustainable growth. However, major technological advances will not be possible without significant improvements to the current design methodology. In this regard, the present research work aims at the development of new design methods and tools that are able to sustain the evolutionary improvement of current aircraft designs, as well as to support the investigation of novel aircraft configurations. To be successful, these design methods and tools must be able to facilitate the aircraft development process as it is currently carried across large and distributed supply chains. Besides, they must account for the increasing scarcity of intellectual resources and the consequent need to increase engineers’ productivity and freeing time for innovation. The Multidisciplinary Design Optimization (MDO) approach appears to be the most promising design methodology in the field of aircraft design, both to improve the performance of traditional aircraft configurations and to support the development of novel concepts. However, a number of technical and non-technical barriers have prevented full exploitation of the MDO approach and, so far, limited its industrial application to detail design cases. To this purpose, the concept of Design and Engineering Engine (DEE) has been developed at the Faculty of Aerospace Engineering in Delft, which is a modular, loosely integrated design system able to support distributed multidisciplinary analysis optimization by automating as far as possible the repetitive and non creative activities that hamper the design and analysis process. One of the DEE technology enabler is the Multi Model Generator (MMG), which actually represents the main outcome of this research work. The Multi-Model Generator (MMG) is a Knowledge Based Engineering (KBE) application developed with the twofold intent of 1) providing designers with a parametric modeling environment to define generative models of conventional and novel aircraft configurations and 2) feeding various analysis tools with dedicated aircraft model abstractions, as required for the verification of the generated design. To meet these objectives, two types of functional blocks have been developed, which constitute the main ingredients of the MMG: the High Level Primitives (HLPs) and the Capability Modules (CMs). Four High Level Primitives have been defined, namely Wing-part, Fuselage-part, Engine and Connection-element. These can be figured out as a suite of advanced LEGO blocks that designers can manipulate to assemble the geometry (external surfaces and structural layout) of the aircraft concept they have in mind. Each HLP has been programmed as a class using the object-oriented programming language of the employed KBE system. This has allowed capturing the design rules that give the HLPs the capability to automatically adapt their own shape and topology, or to trigger events as a reaction of input changes. By means of the editable MMG input file, designers can assign different values to the attributes of each HLP class and call for multiple HLPs instantiations. In this way, both conventional and novel aircraft configurations can be automatically generated and then stretched/morphed into an infinite amount of variants. During the conceptual design phase, designers “see” the aircraft as an assembly of basic solutions to fulfill functionalities, such as generate lift and accommodate payload, rather than an assembly of points, curves, surfaces and solid features. The capabilities to support the designer’ functional thinking and capture knowledge in terms of design rules, have yielded the MMG primitives the “high level” connotation, in contrast with the “low level” primitives of conventional CAD. Once the model of the given aircraft is available, the preparation for the verification phase starts, which requires the set up of the various discipline abstractions (or views) that must be fed to the analysis tools. In the traditional design process, the preparation of these disciplinary models is acknowledged to be lengthy and repetitive, particularly when high fidelity analysis tools are involved. Up to 80% of the overall design process can be wasted just for these preprocessing activities. However, it has been observed that 1) independently from the aircraft configuration at hand, the same analysis tools and preprocessing methods are generally used by specialists; 2) large part of the preprocessing activities is rule-based and require a large deal of geometry manipulation, which actually represent the strengths of KBE technology. To support this phase of the design process, a set of Capability Modules (CM) has been developed to capture the “model preprocessing knowledge” of discipline experts and reuse it to automate the generation of models for a broad range of low and high fidelity analysis tools, both proprietary and commercial off the shelf. The implemented approach has enabled the use of high fidelity analysis tools, such as FEM and CFD, already in the early stages of the design process, which not only increases the level of confidence in the designed product, but provides essential means for the study of innovative aircraft configurations, where semi-empirical and statistics based methods fail and first principle analysis is the only way to go. Due to its ability to be accessed in remote, via web connections, and operated in batch, the MMG also demonstrated to be a valuable asset to support MDO processes across distributed design frameworks. The capability of the MMG has been demonstrated by means of several example applications and two relevant study cases addressed in this work. The first case concerns with the European project MOB, on distributed multidisciplinary design optimization of blended wing body aircraft configurations. The second deals with a MDO system developed in collaboration with Airbus to redesign the vertical tail of an existing passenger aircraft. A side objective of this work was to improve the dissemination of KBE technology, which is still a relatively young discipline that has not yet found the deserved level of attention and understanding, both in the world of industry and academia. To this scope, an extensive and original investigation on the Artificial Intelligence roots of KBE is provided and its object oriented paradigm thoroughly discussed. A best practice section to the development of KBE applications is included as well.","Knowledge based engineering; aircraft design; Multidisciplinary design optimization; Multi Model Generator; High Level Primitive; Capability Module","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration & Operations","","","",""
"uuid:ec4dbcd6-052d-4009-bf9e-cdcbf4614174","http://resolver.tudelft.nl/uuid:ec4dbcd6-052d-4009-bf9e-cdcbf4614174","Mixed-Mode Fatigue Disbond on Metallic Bonded Joints","Bürger, D.B.","Benedictus, R.B. (promotor)","2015","Aerospace structures have been long dealing with the safety versus weight issue. Lighter airplanes are cheaper to operate, however, they may face a safety issue because of the reduced fatigue life. Consequently, a heavier/safer structure is designed. Adhesive bonding is a joining technique that offers potential for improvement in the fatigue behavior of a structure, resulting in reduced weight. However, predicting the fatigue behavior of a bonded joint for its use in a damage tolerance design philosophy still remains a problem with no satisfactory solution. Often, the joint is subjected to a combination of peeling and shearing stresses. Hence, one of the most important factors influencing the fatigue behavior of an adhesively bonded joint is the Mode Ratio. The objective of this investigation was to study of the Mode Ratio on the fatigue behavior of a bonded joint. First, the fatigue disbond mechanisms were investigated throughout the entire Mode Ratio range and compared to fatigue delamination mechanisms. After the mechanisms were identifed, a parameter related to the mechanisms was chosen as similitude in the Paris relation and the Mixed-Mode fatigue disbond model was developed. Later, the model was evaluated on a different adhesive and on a condition of variable Mode Ratio. The fatigue disbond mechanisms study identified the local principal stress as the driving force for the micro-crack formation and growth, and the Mode Ratio was identified as the controlling parameter for coalescence between the micro-cracks. Based on these findings, a parameter directly related to the principal stress was proposed as a similitude parameter. Additionally, a linear interpolation between Mode I and Mode II parameters of the Paris relation was proposed to predict the Mixed-Mode fatigue behavior. Thus, the model predicts the fatigue behavior for the entire Mode Ratio range using only pure Mode I and pure Mode II as inputs. The evaluation of this model revealed that it presents good predictions for Mode Ratios in the range of 0% to 50% and conservative predictions in the range of 50% to 100%. The model also seems to be valid in a variable Mode Ratio condition. The limitations and shortcomings of the model along with the limitations of using a damage tolerance philosophy on adhesive bonding were discussed. Despite these issues, the model is an improvement over the models available in the literature because it captures some of the phenomena involved in the Mixed-Mode fatigue disbond. Additionally, the model also reduces the amount of empirical data required for its implementation.","disbond; damage tolerance; fatigue; Mixed-Mode","en","doctoral thesis","","","","","","","","2015-02-25","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:fc22e459-27f4-405b-8d0d-c21148201639","http://resolver.tudelft.nl/uuid:fc22e459-27f4-405b-8d0d-c21148201639","Efficient numerical methods to compute unsteady subsonic flows on unstructured grids","Lucas, P.","Bijl, H. (promotor)","2010","Over the last four decades the increase in computer power and the advances in solver technology has resulted in an estimated reduction of 10 orders in magnitude to compute flow problems. However, to solve the instationairy Reynolds-averaged Navier-Stokes equations, even today, a massive amount of CPU time may be required. For example, to solve the unsteady flow around a wind turbine, a month of computing time may be required, even on a series of processors. This thesis, therefore, aims at reducing the computing times, especially for unsteady flow computations, by investigating two independent aspects: efficient distribution of grid nodes through grid adaptation and fast nonlinear solvers. With respect to an efficient distribution of grid points the goal is to develop an efficient refinement strategy for solution-based mesh adaptation that is straightforward to implement in existing CFD solvers with grid adapting capabilities. An efficient refinement strategy is required because most refinement strategies that can be found in the literature easily lead to over-refinement, are not fully automated or refine a fixed number of grid cells independent on accuracy considerations. Consequently, these refinement strategies are not guaranteed to yield computationally efficient flow computations. The approach followed is to develop a refinement strategy that aims at constructing a sharp upper bound for the error indicator distribution, for an a priori given number of grid cells. This is a useful approach because a sharp upper bound is a crude approximation of Dirac delta distribution, which is the most efficient distribution regarding computational costs and numerical accuracy. Furthermore, the possibility to a priori define the number of grid cells enables the user to optimize numerical accuracy for a given amount of CPU costs, useful when computing time is limited. The results presented in this thesis show a correlation between the sharpness of the error indicator distribution and numerical accuracy for two-dimensional subsonic flow computations. For three dimensional and supersonic flow computations there is less evidence for such a correlation. The results presented, however, show that the number of grid adaptations is in all cases a rather important parameter regarding the numerical accuracy, something that is not always mentioned in the literature. Finally, for all cases, with the number of grid adaptations carefully chosen, the adaptation strategy yields computationally efficient flow computations when one aims at engineering order of accuracies in the output quantities. With respect to fast nonlinear solvers the goal is to reduce computing times of unsteady flow problems by developing and implementing a Jacobian-free Newton Krylov (JFNK) solution method in a general purpose CFD solver. In addition to reducing the CPU costs compared to the original solver (classic nonlinear multigrid), the new solution method should be relatively insensitive to the various sources of stiffness typically encountered in flow problems, e.g. the Reynolds number, the Mach number and the maximum aspect ratio. Classic nonlinear multigrid typically has difficulties in tackling these stiffness sources such that computing times can dramatically and unexpectly increase for a different flow configuration. A Newton-based method comes natural for unsteady flow computations because the initial solution obtained from the previous time step is usually accurate enough to avoid nonlinear stall or divergence. Furthermore, a Krylov method, in combination with a suitable preconditioner, is less sensitive to the various sources of stiffness encountered in flow problems. An approximate factorization of the Jacobian, that approximately matches the target residual operator, is used to precondition the linear systems. This preconditioner is used because it enables rapid linear convergence and is easy to reuse for the sequences of linear systems that need to be solved. The results presented in this thesis show that a preconditioned JFNK algorithm enables a dramatic reduction in CPU costs compared to standard nonlinear multigrid: when the iteration error is reduced below the temporal error the reduction in CPU costs can be as large as a factor of 25.1. Furthermore, for the ranges tested, the performance of JFNK has been found to be rather insensitive to the stiffness induced by the Reynolds number, maximum aspect ratio, grid density, physical time step and Mach number. Also the complexity induced by fluid structure interaction is easily tackled by JFNK. In addition to the nonlinear solver the efficiency of the temporal discretization and deflation-preconditioning based on coarse grid vectors is addressed. In this it is shown that for engineering order of temporal accuracy, higher order implicit time integration reduces computing times compared to standard second order implicit time integration. Deflation-preconditioning based on coarse grid vectors can either enhance or reduce the overall performance for flow problems and is, therefore, considered liable. Deflation-preconditioning based on coarse grid vectors applied to a symmetric and nonsymmetric (convection)-diffusion equation always improves convergence.","Newton-Krylov; Jacobian-free; ILU(k) preconditioner; unsteady flow computations; refinement strategy","en","doctoral thesis","Uitgeverij BOXPress","","","","","","","2010-06-24","Aerospace Engineering","Aerospace Design, Integration & Operations","","","",""
"uuid:fe35a8ca-a0e6-428c-81b9-22d869eb5b90","http://resolver.tudelft.nl/uuid:fe35a8ca-a0e6-428c-81b9-22d869eb5b90","On an aerospace design representation programming interface","Sharma, N.","Gerhardt, W. (promotor); Torenbeek, E. (promotor); Koppelaar, H. (promotor)","1997","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a23d0dae-c622-47c6-9e3b-4e60f7fa77d9","http://resolver.tudelft.nl/uuid:a23d0dae-c622-47c6-9e3b-4e60f7fa77d9","Enige beschouwingen over de grenslaaginterferentie bij de aansluiting van een draagvlak en een wand","Loos, H.G.","Broer, L.J.F. (promotor)","1952","","","nl","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a05a8c81-5f02-4d12-9417-8fdba05e6983","http://resolver.tudelft.nl/uuid:a05a8c81-5f02-4d12-9417-8fdba05e6983","Isogeometric Shape Optimization for Quasi-static and Transient Problems","Wang, Z.P.","Bisagni, C. (promotor); Turteltaub, S.R. (promotor)","2016","The recently developed isogeometric analysis (IGA) was aimed, from the start, at integrating computer aided design (CAD) and analysis. This synthesis of geometry and analysis has naturally led to renewed interest in developing structural shape optimization. The advantages of using isogeometric analysis in shape optimization are embodied in its ability to preserve exact CAD geometrical descriptions and its enhanced potential to perform shape sensitivity analysis. Recent contributions in shape optimization within IGA have been limited to static or steady-state loading conditions. The purpose of this work was to extend the isogeometric shape optimization and identification to quasi-static and transient problems. The normalization approaches for the search directions in isogeometric shape optimization scheme and the mean value property of B-spline basis were also studied. Shape sensitivity analysis plays a critical role in structural shape optimization. In this dissertation, an adjoint sensitivity analysis was performed for arbitrary objective functionals defined for quasi-static and transient problems at the continuous level. The sensitivity for quasi-static and transient problems are essentially different with each other since the transient case has a time-derivative term involved in the time interval. The transport relations considering discontinuities were studied and used to derive the continuous adjoint shape sensitivity. Consideration of the discontinuities enabled the shape sensitivity analysis to be applicable for the problems where discontinuities were involved in the objective functional and state equations. Then within the context of IGA, the continuous sensitivity was discretized to obtain the discrete design sensitivity with respect to the design discretization, which was used to find the search directions used to update the shape numerically. A interesting phenomenon in shape optimization is that the use of the search direction directly predicted from the discrete shape gradient makes the optimization history strongly dependent on the discretization. This discretization dependency can affect convergence and may lead the optimization process into a sub-optimal solution. The source of this discretization dependency was traced to the lack of consistency with the local steepest descent search direction in the continuous formulation. This inconsistency was analyzed using the shape variation equations and subsequently illustrated with a volume minimization problem. It was found that the inconsistency originates from the NURBS discretization which induces a discrete quadratic norm to represent the continuous Euclidean norm. To fix this inconsistency, a standard normalization approach, which is used to find the steepest descent direction for quadratic norm problems, was proposed to obtain a consistent discretization independent search direction. The standard approach requires solving a linear system of equations. Using the diagonally lumped mapping matrix (DLMM) and the partition of unity property of NURBS, two simpler normalization approaches, which do not require solving a linear system of equations, were proposed. The discretization-independence of the proposed approaches was verified with a benchmark problem. The superiority of the proposed search direction and its suitability for numerical implementation is illustrated with examples of shape optimization for mechanical and thermal problems. In the derivation of the simplified normalization approaches, the mean value property of B-spline basis function is proposed and proved using mathematical induction method. Using the normalization approaches, two frameworks to solve shape optimization and identification problems for quasi-static and transient process, respectively, were developed and implemented numerically within the context of isogeometric analysis. Generalized objective functionals were used to accommodate both structural shape optimization and identification problems in arbitrary forms. The methodology and its numerical implementation were tested using benchmark problems or passive control approaches with priori known solutions. For the quasi-static case, application problems were considered where an external load was allowed to move along the surface of a structure. The shape of the structure was modified to control the time-dependent displacement of the point where the load was applied according to a pre-specified target. For the transient case, the shape optimization and identification was performed for a plunger design under a transient heating process and a thermal protection layer design for a ballistic re-entry vehicle.","isogeometric analysis; shape optimization; continuous adjoint method; quasi-static; transient heat conduction; normalization approaches; discretization/mesh-dependency","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:81b63869-6048-456d-99d2-aeade8da8ad2","http://resolver.tudelft.nl/uuid:81b63869-6048-456d-99d2-aeade8da8ad2","Changes in pilot control behaviour across Stewart platform motion systems","Nieuwenhuizen, F.M.","Mulder, M. (promotor); Bülthoff, H.H. (promotor)","2012","Flight simulators provide an effective, efficient, and safe environment for practising flight-critical manoeuvres without requiring a real aircraft. Most simulators are equipped with a Stewart-type motion system, which consists of six linear actuators in a hexapod configuration. The argument for use of motion systems in simulators is derived from the presence of motion cues during flight. It is hypothesised that if pilots would train in a fixed-base simulator, they would adapt their behaviour and that this would result in incorrect control behaviour when transferred to the aircraft. Similarly, if pilots would train without simulator motion, the presence of motion in flight could disorient the pilot which could have a detrimental effect on performance. Finally, pilots themselves have a strong preference for vestibular motion cues to be present in flight simulators. Therefore, flight simulator motion systems are used to reproduce aircraft motion experienced in flight as faithfully as possible, and to provide the pilot with the most realistic training environment. Flight simulator regulators also allow the use of low-cost motion systems with reduced magnitude motion cues compared to full flight simulators for certain non-type specific training tasks. The limited characteristics of these motion systems, such as shorter actuators, lower bandwidth, and lower smoothness, are hypothesised to have an effect on pilot control behaviour in the simulator. Instead of relying on standard-practise subjective pilot ratings to determine these effects, it would be best to consider human perception and control processes at a skill-based level as a measure for the degree to which a simulator affects pilot perceptual-motor and cognitive behaviour for a given task and environment. Skill-based behaviour represents the lowest level of human cognitive behaviour and involves elementary human information processing and basic control tasks. Investigating this level of human behaviour provides an objective means to assess perception and control behaviour in a simulator environment. Skill-based behaviour can be assessed in simulator trials by taking a cybernetic approach, in which a mathematical model is fit to the measured response of a pilot and changes in the identified parameters serve as a measure for changes in human behaviour. The contribution of visual and vestibular information to control can be measured by performing closed-loop control tasks in which a pilot tracks a target, while at the same time rejecting a disturbance. Observed changes in performance can now be correlated with changes in identified control behaviour, and related to changes in experimental conditions. The goal of this thesis was to apply a cybernetic approach to investigate the influence of limited motion system characteristics of low-cost simulators on perception and control behaviour of pilots. Simulators with high-fidelity motion systems were used as a comparison. An initial motivation was the inconclusive evidence provided by previous studies on the influence of simulator motion, even though many experimental evaluations have been performed. A key reason for the lack of consensus is the limited understanding of human perception and control processes. A multi-modal cybernetic approach can provide a more detailed view by separating the contribution of individual perception channels. A second motivation was that it is unclear how human behaviour in the simulator is affected by limited motion system characteristics of low-cost motion systems. Two objectives were formulated towards the goal of this thesis: 1) assess the motion system characteristics that play a role in pilot perception and control behaviour, and 2) determine the influence of these characteristics on pilot control behaviour in experimental evaluations. By contrasting the limited characteristics of a low-cost motion simulator to those of a high-end simulator, it is possible to specify the properties of motion systems that are most important to human control behaviour. After modelling the properties of a low-cost motion platform and simulating that model on the high-end platform, the limiting motion system characteristics can be varied systematically to represent either simulator, or any 'virtual' simulator in between. The cybernetic approach can then be used to identify pilot control behaviour, and adaptation of pilot control strategies can be related to changes in the motion cues that are available during active control tasks in the simulator. To achieve the first objective, two research simulators were used to investigate the basic properties of simulator motion systems: 1) the MPI Stewart platform, a mid-size electric simulator with restrictive characteristics, and 2) the SIMONA Research Simulator (SRS), a larger hydraulic motion simulator with well-known properties. The characteristics of the MPI Stewart platform were determined using a standardised approach, in which the measured output signal from an Inertial Measurement Unit (IMU) was partitioned into several components in the frequency domain such that the various characteristics of the motion platform could be determined. These included the describing function, low and high frequency non-linearities, acceleration noise, and roughness. The primary finding from these measurements concerned the platform describing function, which was dominated by the standard platform filters implemented by the manufacturer. Outside the 1 Hz bandwidth of the platform filters, the signal-to-noise ratios were very low. Furthermore, the first-order lag constant from dynamic threshold measurements was relatively high, which meant that the platform response to an acceleration step input of 0.1 m/s^2 was slow and only reached 63% after approximately 300 ms. Initially, a relatively high fixed time delay of 100 ms was found between sending a motion command to the platform and measuring its response. The measurements revealed that this was related to the software framework used for driving the simulator, which was subsequently updated. This resulted in a much lower time delay of 35 ms. Based on these performance measurements, a model was developed for the main characteristics of the MPI Stewart platform: its dynamic range based on the platform filters, the measured time delay, and characteristics of the motion noise (or smoothness). After baseline response measurements were performed on the SRS, the model of the MPI Stewart platform was implemented and validated with describing function measurements. The baseline measurements on the SRS showed a dynamic response with a bandwidth higher than 10 Hz and a time delay of 25 ms. Measurements during simulation of the MPI Stewart platform model showed that the SRS could replicate the model response and time delay characteristics, and that the motion noise could be reproduced as well. Thus, the implementation of the total model of the MPI Stewart platform on the SRS was validated and systematic changes could be made to motion system dynamics, time delays, and motion noise characteristics to study their effect on human control behaviour. These findings achieved the first objective of this thesis. The second objective was addressed using a two-step approach. The first step consisted of developing a novel parametric technique for identification of human control behaviour and comparing it to an established spectral method using Fourier Coefficients. It was shown that the parametric method was able to reduce the variances in the estimates by assuming a pilot model structure and by incorporating the pilot remnant. Furthermore, the analytical calculations for bias and variance in both methods were validated with the use of 10,000 closed-loop simulations, and the methods were successfully applied to experimental data of closed-loop multi-channel control tasks. In the second step, it was investigated how the simulator motion system characteristics affected pilot control behaviour, by simulating the model of the MPI Stewart platform on the SRS. The model characteristics were varied systematically in a closed-loop control experiment with simultaneous target and disturbance inputs, such that pilot control behaviour could be estimated for visual and vestibular perceptual channels. Participants performed a pitch tracking task, using a simplified model of the pitch attitude dynamics of a Cessna Citation I. At the same time they rejected a disturbance on their control input. Simulator motion cues were presented in pitch and heave. However, only vertical motion due to rotations around the centre of gravity were considered in this experiment, and the influence of centre of gravity heave was not taken into account. It was shown that the 1 Hz platform filter of the MPI Stewart platform had the largest experimental effect. The bandwidth of the motion system response was limited drastically compared to the baseline SRS response. Participants could not reduce tracking errors effectively, and barely used the motion cues at all in conditions with a limited motion system bandwidth. Instead, participants relied on visual cues to generate lead in their control behaviour necessary for the control task. The experimental evaluation did not show an influence of the difference in simulator time delays (35 ms versus 25 ms) on pilot control behaviour. Similarly, the simulator motion noise characteristics did not have an effect. The disturbances in motion cues due to these characteristics were not large enough to obscure motion information that was relevant to the control task, as the difference in time delay between the MPI Stewart platform and the SRS was only 10 ms and the motion cues due to the motion noise characteristics were small. Therefore, these motion system characteristics did not impair the ability of pilots to generate lead information from the motion cues for the task used in this experiment. However, these motion system characteristics could have a different effect in other experimental tasks, such as measurements on pilot motion thresholds. The second objective of this thesis was fulfilled by determining the influence of motion system characteristics of two research simulators on pilot performance and control behaviour. Future research should focus on applying the cybernetic approach to other types of motion systems. Full flight simulators with electric actuators are a prime candidate for this approach as they are replacing hydraulically driven simulators, and specifications about their motion systems are rarely published. Furthermore, flight simulators are mainly used for pilot training. Simulator motion rarely shows an effect in studies on transfer of training from simulator to aircraft, whereas it can have a pronounced effect on pilot control behaviour as has been shown in this thesis. Efforts to bridge the gap between these research fields should investigate requirements for simulator motion in pilot training, for motion system tuning, and for experimental control tasks. A related research question exists in understanding the influence of simulator motion in more ecologically valid piloting tasks. Higher-level piloting tasks could be investigated by extending the cybernetic approach to more cognitive aspects of human behaviour. Additionally, more basic research is required for looking into the different components that contribute to forming a percept of motion. For instance, the influence of proprioception and somatosensory feedback is not well understood. The approach used in this thesis provided valuable insight into changes in pilot response dynamics that form the basis of observed changes in performance. The results demonstrated that simulator motion cues must be considered carefully in piloted control tasks in simulators and that measured results depend on simulator characteristics as pilots adapt their control behaviour to the available cues.","cybernetic approach; multi-modal control behaviour; motion system characteristics; Stewart platform","en","doctoral thesis","F.M. Nieuwenhuizen","","","","","","","2012-07-05","Aerospace Engineering","Control and Simulation","","","",""
"uuid:960a94b4-09ef-47fd-b2ba-1e186b7e3a09","http://resolver.tudelft.nl/uuid:960a94b4-09ef-47fd-b2ba-1e186b7e3a09","Hot tearing and deformation in direct-chill casting of aluminum alloys","","Katgerman, L. (promotor)","2005","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:349c05b4-cb94-4dd1-bdd0-4edd03bf08b9","http://resolver.tudelft.nl/uuid:349c05b4-cb94-4dd1-bdd0-4edd03bf08b9","Unsteady Flow Organization of a Shock Wave/Boundary Layer Interaction","Humble, R.A.","Scarano, F. (promotor); Van Oudheusden, B.W. (promotor)","2009","A fundamental experimental study is carried out to investigate the unsteady flow organization of an incident shock wave/turbulent boundary layer interaction at Mach 2.1. Planar and tomographic particle image velocimetry (PIV) are used in combination with data processing using the proper orthogonal decomposition (POD), complemented with hot-wire anemometry (HWA) and nonlinear time series analyses. It is found that the global structure of the interaction region varies considerably in time and the mean flow-field is a simplified representation of a more complex instantaneous structure. An inter-relationship appears to exist between the incoming boundary layer, separated flow region, and reflected shock wave. The incoming boundary contains large-scale coherent motions, in the form of three-dimensional streamwise-elongated regions of relatively low- and high-speed fluid. The reflected shock wave region conforms to these regions as they enter the interaction, and may be viewed as a supposition of a streamwise translation and a spanwise rippling. The HWA results reveal that the reflected shock wave region contains energetic frequencies an order of magnitude lower than those found within the undisturbed boundary layer at the same distance from the wall. The time series is shown to be represented as a chaotic attractor in a limited dimensional state-space. This attractor has a rich, underlying structure, which contains the signatures of the low- and high-speed regions as they enter the interaction.","boundary layer; shock wave; interaction; unsteady; turbulence; particle image velocimetry; tomography; high-speed; proper orthogonal decomposition; chaos theory; dynamical systems","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:fdc2dbda-b419-450f-a305-64825a43a0c8","http://resolver.tudelft.nl/uuid:fdc2dbda-b419-450f-a305-64825a43a0c8","Global Optimization using Interval Analysis: Interval Optimization for Aerospace Applications","Van Kampen, E.","Mulder, J.A. (promotor)","2010","Optimization is an important element in aerospace related research. It is encountered for example in trajectory optimization problems, such as: satellite formation flying, spacecraft re-entry optimization and airport approach and departure optimization; in control optimization, for example in adaptive control algorithms; and in system identification problems, such as online aircraft model identification or human perception modeling. The main goal of this thesis is to investigate how Interval Analysis (IA) can be used as a tool for aerospace related optimization problems; to examine its theoretical and practical limitations, and to explore the ways in which optimization algorithms can benefit from interval analysis. A subset of goals is to improve the solutions for a number of aerospace related optimization problems. The scientific contribution of this thesis consists of the design and implementation of interval optimization algorithms for four important aerospace problems. The first contribution concerns finding the trim points for a nonlinear aircraft model. Trim points, defined as the combination of control settings for which all linear and rotational accelerations on the aircraft are zero, are important for flight control system design, since they provide information about the flight envelope and stability properties of the aircraft. Unlike other trim algorithms, the interval based method can guarantee that all trim points are found. In the second application, an interval optimization algorithm is developed for fitting pilot input/output data from an experiment in the SIMONA Research Simulator to a multi-modal human perception model. Perception models improve the understanding of how humans perceive motion and are an essential tool in the design of flight simulators. Results show that the minimum of the cost function found by the interval method is lower than the one previously found, resulting in an improved human perception model. This second application particularly demonstrates the capabilities of IA optimization as a parameter identification tool. The third contribution is an interval based algorithm for solving the integer ambiguity problem related to Global Navigation Satellite Systems (GNSS). Phase measurements of the carrier wave of a GNSS signal are used to estimate the length and orientation of baselines between two or more antennas. This estimation procedure contains an optimization problem in which the integer number of carrier wavelengths between antennas has to be determined. The new interval method provides guarantees that correct solutions are found when the measurement noise is encapsulated by an interval number. The final contribution is an interval optimization algorithm that minimizes fuel consumption during rendezvous and docking procedures of satellites in circular orbits. To avoid integration of interval functions, an analytical solution to the system of differential equations that describes the relative motion of the satellites is used to generate trajectories resulting from a set of thruster pulses of varying amplitudes. Introduction of obstacles, in the form of forbidden areas in the path between the two satellites, makes the problem nonlinear, such that gradient-based optimization algorithms can fail to obtain the globally optimal solution. The interval algorithm always converges to the trajectory that avoids all obstacles and results in minimum fuel consumption. It can be concluded that IA is an excellent tool for solving nonlinear optimization algorithms, providing guarantees on obtaining the global minimum of the cost function.","optimization; interval analysis","en","doctoral thesis","","","","","","","","2010-09-24","Aerospace Engineering","Control and Simulation","","","",""
"uuid:da96d0cf-5ee8-4601-be31-669a269bbc9d","http://resolver.tudelft.nl/uuid:da96d0cf-5ee8-4601-be31-669a269bbc9d","On the aerodynamic optimization of supersonic wings","Bos, H.J.","Steketee, J.A. (promotor)","1984","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Engineering","","","",""
"uuid:c5ffe6bc-5106-4456-85c0-09febc3717cc","http://resolver.tudelft.nl/uuid:c5ffe6bc-5106-4456-85c0-09febc3717cc","Synthesis and properties of lyotropic poly(amide-block-aramid) copolymers","De Ruijter, C.","Picken, S.J. (promotor)","2006","This thesis describes the synthesis and properties of liquid crystalline block copolymers comprised of alternating rigid and flexible blocks for the preparation of self-reinforcing materials. The incentive for this work was the expectation that the rigid segments would phase separate on a microscopic scale, and would form nematic domains, which will cause an enhanced orientation of the flexible segments leading to coil stretching. As a result the coils in the copolymer will be stiffer compared to unstretched coils, and the mechanical properties will be better than expected from the pure flexible polymer, therefore the term ""self-reinforcement"". For this purpose a block copolymer was synthesised that is comprised of alternating rigid poly(p-phenylene terephthalamide) (PPTA) (commercially known as Twaron or Kevlar) blocks and flexible coil polyamide 6,6 (commercially known as nylon 6,6) blocks. It is shown that if the aramid content in the copolymers is at least 50 mol% the polymers are able to show a lyotropic liquid crystalline phase in sulphuric acid. From these liquid crystalline solutions fibers have been spun that show promising mechanical properties. Due the combination of the rigid blocks providing stiffness and flexible blocks providing elasticity these block copolymers may be considered in high energy absorption applications.","block copolymers; liquid crystals; fibers","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ea1f0cf0-4e48-421b-b7ae-4ae3e36d1880","http://resolver.tudelft.nl/uuid:ea1f0cf0-4e48-421b-b7ae-4ae3e36d1880","Troposphere Modeling and Filtering for Precise GPS Leveling","Kleijer, F.","Teunissen, P.J.G. (promotor)","2004","Precise height differences (5--10 mm standard deviation) are of interest for applications such as maintenance of the Amsterdam Ordnance Datum and deformation analysis. For these applications the Global Positioning System (GPS) is a cost-effective alternative for classic leveling techniques. However, the constituents in the troposphere, of which water vapor is both spatially and temporally the most variable component, cause the GPS signals to be delayed. Several types of troposphere modeling are investigated for GPS leveling because the geometry causes the height component to be strongly affected by the signal delays. The dissertation describes physical, functional, and stochastic aspects of this modeling and gives recursive filtering techniques that can be used in the data processing. Static networks or baselines with geodetic receivers collecting two-frequency phase observables were assumed. The most important models and filters are implemented in simulation software with which the sensitivities of the height difference are analysed. By frequent estimation of zenith delays using mapping functions, biases in the filtered height differences can be largely avoided, but the use of spatiotemporal constraints with that turns out to have hardly a positive contribution and can even have a precision-deteriorating effect. A stochastic model for slant delays based on Kolmogorov turbulence shows to be potentially precision improving (10--30% of the standard deviation), but this model is to be validated. Furthermore, the simulations show that, even for observation times longer than three hours, correctly resolving the GPS phase ambiguities has a precision improving effect of 15--20%.","gps; heights; troposphere; filtering","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a5afd816-4b04-459d-b54c-da93e3b8a0d7","http://resolver.tudelft.nl/uuid:a5afd816-4b04-459d-b54c-da93e3b8a0d7","Simulation Fidelity Theory and Practice","Roza, Z.C.","Mulder, J.A. (promotor)","2005","Simulation fidelity is an intrinsic element of any simulation system, one that all its developers and users have to deal with one way or the other. It is commonly recognized by the modeling and simulation community that simulation fidelity is an essential vehicle in properly assessing the validity and credibility of simulation results. Furthermore, fidelity is one of the main cost-drives of any model or simulation development. Rigorous assessment of fidelity is, however, one of the most difficult and hard to grasp issues within the model and simulation community. Substantial and exhaustive research endeavors in this area are very limited. Due to this, simulation fidelity still remains a hardly touched upon and rather uncultivated area. This thesis tries to fill this void by the analysis, extension and integration of existing simulation fidelity approaches into a single unified fidelity theory and practice. All this is done from a general simulation system life cycle perspective, not limited by any specific application or problem domain aspects. The foundation for this developed unified fidelity framework comprises a precise mathematical formulation for fidelity and the fundamental concepts underlying its characterization and measurement. The unified fidelity framework is completed with a fidelity management process model outlining a series of generic stages, activities and tasks, which together provide a structured but generic approach to properly integrate and apply all other unified fidelity framework elements in the simulation system development and validation process.","fidelity; simulation; validation; flight simulator; aerospace; verification; certification","en","doctoral thesis","DUP Science","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8ffbde9c-b483-40de-90e0-97095202fbe3","http://resolver.tudelft.nl/uuid:8ffbde9c-b483-40de-90e0-97095202fbe3","Propeller Wing Aerodynamic Interference","Veldhuis, L.L.M.","Bakker, P.G. (promotor)","2005","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a30b358e-d0de-4a81-92f3-e9f255443043","http://resolver.tudelft.nl/uuid:a30b358e-d0de-4a81-92f3-e9f255443043","Finite Element Modeling of Vibrations in Canvas Paintings","Chiriboga Arroyo, P.G.","Benedictus, R. (promotor)","2013","Preventing vibration damage from occurring to valuable and sensitive canvas paintings is of main concern for museums and art conservation institutions. This concern has grown in recent years due to the increasing demand of paintings for exhibitions worldwide and the concomitant need for their handling and transport. The vibration of the canvas can produce progressive delamination of cracked paint in aged paintings which may cause paint loss after repetitive vibration exposure. In the cultural heritage world, there is limited knowledge about the vibration behavior of the canvas and its relation with the damage produced in the paint. The goal of this investigation was to improve this understanding about the vibration behavior of canvas paintings through the use of finite element modeling. A model was developed with the capability of predicting the natural frequencies and mode shapes of canvas paintings, and providing a fundamental understanding of the parameters that influence their dynamic behavior. Canvas paintings exhibit vibration behavior of thin orthotropic plates dominated by the tension and mass of the canvas with negligible bending stiffness. The model was verified and optimized experimentally using a specially designed vibration testing system for canvasses, showing differences within 5% between the first two predicted and measured natural frequencies. Follow-up work to study the non-uniform biaxial tension and to improve the canvas textile material model is needed in order to improve the accuracy of the vibration model for higher modes. Further research is also required to better understand the delamination of paints due to vibration (cyclic) loading. Combined with this model, this will better assist museums and conservators taking precautions and making decisions about vibration exposure and tolerable levels.","vibrations; canvas paintings; finite element modeling; natural frequencies; mode shapes","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Structural Integrity","","","",""
"uuid:67e84328-459e-40e0-8fdf-397ee9eedaf0","http://resolver.tudelft.nl/uuid:67e84328-459e-40e0-8fdf-397ee9eedaf0","Re-entry flight clearance","Juliana, S.","Mulder, J.A. (promotor)","2006","The objective of the research was to identify and evaluate promising mathematical techniques for re-entry flight clearance. To fulfil this objective, two mathematical methods were investigated and developed: μ analysis for linear models and interval analysis for both linear and non-linear models. The stability of re-entry vehicles in the presence of model uncertainties was chosen as the clearance criterion, which is represented by two mathematical criteria: worst-case eigenvalues (linear) and the Lyapunov stability (non-linear). Two vehicle models including flight control systems were developed and used as case studies for the evaluation of the clearance techniques. These models are based on the DART (Delft Aerospace Re-entry Test Demonstrator) and SPHYNX (Subscale Precursor Hypersonic X) re-entry vehicle models. The suitability of the two mathematical techniques for re-entry flight clearance was evaluated based on the results of the clearance application on these models. Non-linear simulations were also performed to verify the clearance results generated by the two techniques. Non-linear interval analysis has been found to be the most reliable method of all other methods investigated in this research, because it could perform the clearance for the non-linear dynamic models of the re-entry vehicles with uncertainties, and the results were confirmed by the non-linear simulations.","stability; robustness; closed-loop system; nonlinear; lyapunov function; interval; clearance; re-entry","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:94fd1664-9fdc-4868-b2c6-d977c0fbc2e2","http://resolver.tudelft.nl/uuid:94fd1664-9fdc-4868-b2c6-d977c0fbc2e2","Conceptual Design Automation: Abstraction complexity reduction by feasilisation and knowledge engineering","Schut, E.J.","Van Tooren, M.J.L. (promotor)","2010","In order to keep innovating, engineers are working more and more with engineering software, providing them a way to cut away their routine and repetitive activities. Computer aided design and simulation software are for instance considered standard tools in most engineering companies. Today, to solve complex engineering design problems, multidisciplinary design optimisation (MDO) is increasingly used to automate the design process to support the engineer in finding a solution faster. To effectively use MDO, design frameworks such as the design and engineering engine (DEE) are required. More and more does engineering software provide a seamless integration of computer software and human knowledge, a focus point of the field of knowledge engineering (KE). This will free engineers from repetitive and routine tasks and allow them to use their full creative capacity and learn faster, increasing their productivity. This work contributes to the development of KE applications within the DEE to support the MDO process. The focus is on the conceptual design phase of complex systems engineering, responsible for providing an initial start vector for MDO. Aircraft design is taken as a guiding example as it is a typical case of a complex system.","Knowledge Based Engineering; Conceptual Design; Aircraft Design; Feasilisation; Multidisciplinary Design Optimisation; Systems Engineering; Complex systems; Design Automation","en","doctoral thesis","E.J. Schut","","","","","","","","Aerospace Engineering","Design of Aircraft and Rotorcraft","","","",""
"uuid:cee40186-6a76-4843-b740-0c0df081b87e","http://resolver.tudelft.nl/uuid:cee40186-6a76-4843-b740-0c0df081b87e","Flying GLARE","Beumler, T.","Vogelesang, L.B. (promotor); Van Tooren, M. (promotor)","2004","At the end of the second millennium did the aircraft industry decide for the first time to apply the fiber metal laminate GLARE in a large quantity on a civil transport aircraft. It was focused on an application of the material on the pressurised fuselage, the decision driven by the demand for weight saving at an affordable cost level. GLARE material properties are linked to both, monolithic aluminium properties as well as fiber composite properties, with the preference depending on the particular strength feature under investigation. Between others, three major structural mechanic advantages compared with monolithic aluminium can be identified for fiber metal laminates, i.e. the lower density, the crack bridging capability of the fibers in presence of a fatigue crack in the particular aluminium sheets and the possibility to tailor the material according to structural mechanic requirements by appropriate orientation of the fibers. Essential for an economic application of the material is the acceptance of 'flying with undetectable fatigue damages'. This rule and it's implications on structural sizing and justification is discussed in depth in this report, leading to the particular subject of the strength behaviour of riveted joints in a fatigued condition. Because GLARE contains an epoxy resin prone to moisture absorption, strength degradations due to environmental influences have to be taken into account. However, as for other materials, it is searched for a realistic exposure in order to design a structural component to the limits of the material strength and to avoid unnecessary high reserves. An outdoor exposure program is under evaluation as part of the structural investigation, which extends the time frame of this thesis. Structural components are supposed to remain for up to 6 years on a tropical exposure site. However, evaluated weight gain measurements allow extrapolations for 30 years aircraft operation and the definition of a representative accelerating ageing process. Extensive results on particular GLARE related investigations are reported since the end of the 1980's. This thesis is compiling the available information on fatigue issues and environmental related material issues, it is extending the previous research and it interprets the material properties within the framework of the mandatory airworthiness rules. For that purpose, two structural items which are tested by Airbus under full scale conditions are investigated concerning all particular strength properties which are required for certification or not are investigated. The application of airworthiness regulations which are defined for monolithic aluminium are discussed for GLARE in chapter 1. While fatigue sensitive monolithic aluminium structures have a relatively long crack initiation life but a relatively short crack propagation life, GLARE shows the opposite behaviour. What does that mean for the certification of a GLARE structure? Which fatigue methods should be used for the certification and is GLARE a single load path or a multiple load path structure? Some basic rules are discussed and proposals concerning the structural certification are provided. No type certification of a commercial passenger aircraft is accepted without test substantiation. The test pyramid is starting with elementary specimens (can be tested early in a project) and finishes with a full scale fatigue test. Chapter 2 discusses the particular influences which have to be considered for structural certification, e.g. crack initiation scatter and temperature sensitivities to crack initiation, and which have to be reconsidered for GLARE. Chapter 3 presents all specimen types which belong to the outdoor exposure program, i.e. test series from which some specimens are shipped to a tropic exposure site and some are tested under laboratory conditions, for comparison. The relevance of the particular specimen types and their history for GLARE is briefly discussed. A review of accelerating ageing experiences of previous researches with Fiber Metal Laminates is done in chapter 4. Diffusion coefficients for GLARE3 made of 2024T3/FM94 are determined. First weight gain measurements which are available from the outdoor exposure test site are investigated and interpreted in chapter 5. Predictions of the weight gain of GLARE around bore holes for both, long range aircraft and short range aircraft, are performed. Chapter 6 presents elementary specimen test results for the two tested materials, related to different ageing conditions. First experiments with specimens which have been exposed for one year outdoors are included. The crack initiation and crack propagation scatter for a row of bore holes is determined. Chapter 7 is dealing with coupon specimens, which are representative for the full scale structure tested by Airbus. A review and calibration of crack initiation, crack propagation and residual strength methods under development by Airbus Deutschland and Delft University is performed for a prediction of the full scale behaviour. The calculated results are discussed in view of a fatigue & damage tolerance certification. Full scale test results are related to the elementary- and the coupon experiments performed in this thesis. The outdoor exposure investigation is extended by a few panel tests, i.e. non-stiffened riveted repair panels, non-stiffened bonded repair panels and door corner cut out specimens. This analyses are collected in chapters 9 to 11. All experiments and analysis are performed with/for GLARE composed of aluminium 2024T3 and prepreg FM94/S-glass, cured at 120°C. Due to the wide range of specimen types each of them couldn'd be provided in a high quantity, for economic reasons. Therefore just property trends can be provided. The investigations performed in frame of this thesis contribute to the verification of the TU Delft / Airbus computer program 'FML F&DT Toolbox', which is developed at the same time.","GLARE; aircraft certification; structural strengths; environmental influences","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4de38d6f-8f68-4706-bf34-4003d3dff0ce","http://resolver.tudelft.nl/uuid:4de38d6f-8f68-4706-bf34-4003d3dff0ce","The inaudible symphony: On the detection and source identification of atmospheric infrasound","Evers, L.G.","Simons, D.G. (promotor); Gisolf, A. (promotor)","2008","Sound becomes inaudible if it consists of frequencies lower than 20 Hz, i.e. the human hearing threshold, and is called infrasound. Low frequency acoustic signals were first discovered after the eruption of the Krakatoa (Indonesia) in 1883. Due to its low frequency content, this infrasound traveled up to seven times around the globe while reaching altitudes over 100 kilometer. The ability to detect explosions with infrasound resulted in substantial scientific and societal interest during World War I and the era of atmospheric nuclear testing. This interest diminished as nuclear tests were confined to the underground under the Limited Test Ban Treaty in 1963. Recently, with the signature of the Comprehensive Nuclear-Test-Ban Treaty, infrasound gained renewed attention as it is being used as a verification technique. This thesis describes the complete sequence of measuring, processing and interpreting infrasound data. A microbarometer was developed and deployed in arrays to measure infrasound. Array processing and statistical detection techniques are applied to extract signals of interest from the continuous recordings. Knowledge on the atmospheric propagation appeared essential in identifying infrasonic sources, like meteors, volcanoes, sea waves and accidental chemical explosions. A large amount of coherent infrasound is continuously being detected from both natural and man-made sources, i.e. the inaudible symphony. Applications are foreseen in acoustic remote sensing where infrasound can be used as passive probe for the upper atmosphere. Non-acoustic phenomena, like gravity waves, can also be detected with the methods described in this thesis.","infrasound; acoustics; geophysics; atmosphere","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4a6ce65b-21e3-42aa-ba30-962d5cbbbca1","http://resolver.tudelft.nl/uuid:4a6ce65b-21e3-42aa-ba30-962d5cbbbca1","Aircraft technology's: Contribution to sustainable development","De Haan, A.R.C.","Walker, W.E. (promotor)","2007","Aviation brings many advantages to society, reflected in its huge growth figures. But, aviation is also criticized for its many undesired effects. Sustainable Development as a concept is brought forward by many of the actors in the aviation system as a way in which aviation can develop itself in order to reduce its undesired effects. Some actors refer to expected large technological changes as a potential solution for the undesired effects of aviation in all categories of Sustainable Development. This research tries to find out if there is some truth in that last claim, by addressing the following question: What is the potential of a set of expert-selected new aircraft technologies to contribute to Sustainable Development; i.e. what is their potential to reduce actor defined adverse effects of flying while keeping the benefits? Given the results of this research, the expert-selected and assessed technologies have a potential to contribute to some characteristics of Sustainable Development, but, technology cannot keep up with the predicted growth in air travel demand, which increases the adverse effects of aviation. In addition, implementation of new technology and replacement of old technology takes a long time -- up to 40 years. Many roadblocks (e.g. airport infrastructure adaptations) need to be taken out of the way. Psychological mechanisms, such as discounting and fairness appraisal, play a delaying role in the implementation process. For the aviation system as a whole, two important drivers for innovation appear to be lacking: sense of urgency for change and availability of sufficient amounts of money. It is recommended that serious investments be made and incentives created to stimulate the development of other technologies that can contribute to sustainability. In addition, one might search for other options than technology to improve the contribution of aviation to Sustainable Development.","sustainable development; scenarios; technology; aviation; systems analysis","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3139e68e-d1c4-4dec-8c57-504b0621ad56","http://resolver.tudelft.nl/uuid:3139e68e-d1c4-4dec-8c57-504b0621ad56","Stiffness and Layout Tailoring of a Morphing High-lift System with Aeroelastic Loads","Thuwis, G.A.A.","Gürdal, Z. (promotor)","2012","","morphing; high-lift; aeroelasticity; composites; topology optimisation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:dbd8025c-c660-452b-8b0b-391c8ad3a89f","http://resolver.tudelft.nl/uuid:dbd8025c-c660-452b-8b0b-391c8ad3a89f","Delamination Growth in Composites under Fatigue Loading","Khan, R.","Benedictus, R. (promotor)","2013","Fiber reinforced composites are attractive for aerospace applications due to high specific strength and stiffness. Their use has been gradually increased to 50% by weight of the aircraft over past decades. As a consequence, modern aircraft utilize composites in the primary structures like wing skin and fuselage. The use of composites in primary structures has increased the need for reliable strength assessment methodologies. Composites are inherent to various damage types of which delamination is the most severe type of damage. Delaminations may grow due to fatigue resulting in the stress redistribution and potentially leading to structural failure, thus making fatigue an important design concern. Damage tolerance of aircraft structures is a key aspect in maintenance and safety of aircraft. For damage tolerant design of structures, the development of accurate delamination growth assessment tools is necessary. Delamination growth is affected by both cyclic and monotonic part of the fatigue load cycle. The effect of monotonic part is known as stress ratio (ratio of minimum to maximum cyclic stress) effect on delamination growth, and it has been extensively studied in the literature. Chapter 2 provides a detailed review of the literature concerning the stress ratio effect on delamination growth. The literature review shows that previous studies empirically relate delamination growth to a driving force parameter that seems not based on physical mechanisms. Studies are present where mechanisms of delamination growth have been investigated; however there is a lack of efforts to link these quantitatively to delamination growth models. The objective of this thesis is the development of a mechanistic model for delamination growth that is based on the observed delamination mechanisms and the effects of monotonic and cyclic loadings in fatigue. The thesis is based on the hypothesis that both monotonic and cyclic loading affect fracture surface formation, which can be used for delamination growth characterization. The secondary objective of the thesis is the characterization of fracture surfaces for the effect of monotonic and cyclic loading. To limit the scope, delamination growth under mode I fatigue has been investigated in the thesis. The approach of the thesis is experimental. Delamination growth is characterized experimentally both on macroscopic and microscopic levels, as described in chapter 3. Fatigue tests were performed on double cantilever beam (DCB) specimens to investigate delamination growth behavior under different stress ratios. Specimens were made from cured laminates of M30SC/DT120 carbon/epoxy prepregs. Crack closure during delamination growth was investigated using a clip gauge extensometer. The effect of fiber bridging was investigated by cutting bridging fibers during delamination growth experiments. Microscopy of the fracture surfaces was performed using scanning electron microscopy. Width tapered DCB (WTDCB) specimens were used for the delamination growth tests under fatigue with constant monotonic and cyclic load during delamination extension. Results of the fatigue tests and microscopy are presented in chapter 4. The delamination growth rate has been related to the strain energy release rate (SERR). The SERR range has been defined such that it resembles the correct analogous to the stress intensity factor (SIF) range. For constant SERR range, the delamination growth rate is higher for higher stress ratios. Crack closure was observed to occur for the lowest stress ratio applied in the tests. Fractographic analysis of the fracture surfaces revealed broken fibers, loose fibers, hackles and striations. The striations and hackles on the fracture surfaces of WTDCB specimens were quantitatively analyzed for different combinations of monotonic load and cyclic load amplitudes. It was observed that striation spacing increased with monotonic and cyclic load. The hackle length increased with monotonic load, but decreased with the cyclic load amplitude. Crack closure and fiber bridging marginally explain the stress ratio effect on delamination growth, as discussed in chapter 5. Crack closure increases the effective minimum load at crack tip at the lower stress ratio only. This results in higher effective stress ratio at the crack tip. In this case, the SERR range was corrected for crack closure. By plotting delamination growth rate against corrected SERR range, the data shifted to the region with higher stress ratios. To illustrate the effect of crack closure in 3D representation, delamination growth rate was plotted against SERR range and maximum SERR. It was observed that the data corrected for crack closure shifted to the higher stress ratio region, while remaining on the same crack resistance surface. It was further observed that fiber bridging decreases the delamination growth rate. The stress ratio remains the same. It was observed that fiber bridging affects both minimum and maximum loads during fatigue resulting in same stress ratio as without fiber bridging. In a 3D representation of delamination growth rate versus SERR range and maximum SERR, the data was observed to shift to the lower delamination growth rate region due to fiber bridging. The experimental results showed that delamination growth is not a unique function of SERR range, but also depend on the stress ratio. This implies that delamination growth depends on both cyclic and monotonic loads. A two parameter model for delamination growth was developed based on the observation of the effect of cyclic and monotonic load on the fracture surfaces. Chapter 6 describes the mechanism of delamination growth and the development of the mechanistic two parameter model for delamination growth prediction. The two parameter components in the model are superimposed rather than multiplied in agreement with the superposition of the effects of cyclic and monotonic loads observed with microscopic features on the fracture surfaces. The two parameter model for delamination growth represents a crack resistance surface for the material in the 3D coordinates of delamination growth rate versus SERR range and maximum SERR. The model has been implemented using data from the delamination growth experiments. The surface fitting tool of the commercial software MATLAB was used to obtain the equation. To validate the model, experimental data was taken from the literature. The predictions with the model and the reported experimental observations were observed to be in good agreement. The current model is different from previous models in that the relation between delamination growth and correlating parameters is no longer a simple fit of the experimental data by regression. The fit is rather an educated fit based on the observed contribution of monotonic and cyclic load components on fracture mechanisms. The two parameters in the model are superimposed to describe contribution of the load components. In previous two parameter models the terms were multiplied without justification using the physics of delamination growth. The conclusions of the thesis are summarized in chapter 8. It can be concluded that the effect of monotonic load on delamination growth is not fully explained by crack closure and fiber bridging. The delamination growth should be characterized using both monotonic and cyclic load components. These load components affects delamination growth at microscopic level independent of one another. The two parameter terms in the model are added in conjunction to the superposition of the effects of these parameters on microscopic features. It is concluded that the model can be extended to the delamination growth in different modes of fracture.","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:957b041a-8e2c-4ad7-be73-214c0727df01","http://resolver.tudelft.nl/uuid:957b041a-8e2c-4ad7-be73-214c0727df01","The use of satellites in gravity field determination and model adjustment","Visser, P.N.A.M.","Wakker, K.F. (promotor)","1992","","","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7f7d98b2-aac4-433b-92b9-a990975c0b23","http://resolver.tudelft.nl/uuid:7f7d98b2-aac4-433b-92b9-a990975c0b23","Design of Low Drag Bluff Road Vehicles","Van Raemdonck, G.M.R.","Van Tooren, M.J.L. (promotor)","2012","Low drag bluff road vehicle design can be obtained effectively and efficiently with a three phase approach that uses numerical simulations, scaled wind tunnel experiments and full-scale road testing. By applying this generalised method, SideWings were developed for an improved trailer underbody flow and tails for the trailer's rear-end. A combination of these aerodynamic devices resulted in fuel savings of up to 3 l/100 km. Further improvements could be obtained by an integral vehicle design when the front of the bluff body is redesigned as well. Although front adjustments of a bluff body are less effective, they have an influence on the drag reduction of rear-end devices, which are necessary to aerodynamically improve bluff bodies.","transport; bluff body; aerodynamic; heavy duty vehicle; trailer; drag reduction","en","doctoral thesis","","","","","","","","2012-06-01","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:5fbc2ef8-5c1a-4a42-b6a1-3c8d66ca658d","http://resolver.tudelft.nl/uuid:5fbc2ef8-5c1a-4a42-b6a1-3c8d66ca658d","Large deflection panel flutter","Zeijdel, E.F.E.","Van der Neut, A. (promotor)","1962","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a1060bb0-88db-4766-ada5-33bc3e920e55","http://resolver.tudelft.nl/uuid:a1060bb0-88db-4766-ada5-33bc3e920e55","Aspects of POD-based wall-layer modeling for the variational multiscale methods","Chen, L.","Bijl, H. (promotor); Hulshoff, S.J. (promotor)","2015","","","en","doctoral thesis","Delft University of Technology","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:cd10b996-affb-4aea-99a2-181a6fa21995","http://resolver.tudelft.nl/uuid:cd10b996-affb-4aea-99a2-181a6fa21995","Multiscale analyses of fibre metal laminates","Cid Alfaro, M.V.","De Borst, R. (promotor)","2008","The advance of composites used in aerospace, civil and biomechanical engineering and other technology branches over the last decades has led to a substantial increase in the application of these materials. In addition, the search for new and improved materials in aerospace industry has stimulated the development of hybrid materials partly made out of composites, such as Fibre-Metal Laminates (FMLs). These materials are composed of alternatively stacked aluminium and fibre-reinforced composite layers such that the best features of both constituents are combined. FMLs also have additional advantages over conventional monolithic aluminium alloys and fibre-reinforced composites, such as an excellent fatigue and damage-tolerance behaviour. Furthermore, this class of materials possesses good fire, impact, damping, insulation and corrosion-resistance properties.To ensure a maximal reliability under service conditions, the failure mechanisms of FMLs must be well understood. The main mesoscale failure mechanisms that endanger their overall reliability are delamination between adjacent plies, cracking, and plasticity in individual metal layers. Important failure mechanisms at the microscale are debonding of fibres, fibre breakage, pull-out of broken fibres and crack growth in the epoxy matrix.Finite element simulations serve as an important tool for understanding the mechanical failure behaviour of FMLs in engineering applications. However, the performance of a direct numerical analysis of an engineering structure (e.g., an aircraft wing), where all features of the underlying heterogeneous microstructure are accounted for explicitly, requires an extremely fine finite element mesh and thus an impractical amount of computational time. A more efficient approach is to study engineering structures with the aid of mesoscale material models that account for the underlying microstructure in an average sense. The average properties in the mesoscale model can be computed using a numerical homogenization approach, where the microstructural stresses and deformations are averaged over a representative material volume. The present thesis comprises a detailed study of the failure behaviour of fibre-metal laminates at the meso- and microscale levels, and proposes a numerical homogenization framework that links specific failure mechanisms at these two levels of observation.","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3d168259-c397-4640-826e-a16bf315656c","http://resolver.tudelft.nl/uuid:3d168259-c397-4640-826e-a16bf315656c","Space-time multiscale methods for Large Eddy Simulation","Munts, E.A.","De Borst, R. (promotor)","2006","The Variational Multiscale (VMS) method has appeared as a promising new approach to the Large Eddy Simulation (LES) of turbulent flows. The key advantage of the VMS approach is that it allows different subgrid-scale (SGS) modeling assumptions to be made at different ranges of the resolved scales. Typically, in the VMS method, SGS modeling is confined to the smallest resolved scales, leaving the dynamically important large scales free from the direct influence of the SGS model. Prior implementations of the VMS approach have been restricted to either incompressible formulations, simple geometries and/or small time steps. We propose a space-time VMS method for the compressible Navier-Stokes equations, which aims to overcome the difficulties associated with prior VMS implementations. In particular, we aim to develop a method that is applicable to complex flow geometries with a minimum number of degrees of freedom, and that can march at time steps which are chosen to resolve the physical phenomena of interest rather than to satisfy stability constraints. The spatial discretization of the proposed computational approach corresponds to a high-order continuous Galerkin method, which due to its hierarchical nature provides a natural framework for 'a priori' scale separation, which is crucial for the VMS method. As the method is formulated in a space-time framework, it supports continuous as well as discontinuous discretizations in time. Time-discontinuous discretizations offer great flexibility for adaptation, but may be computationally expensive. Time-continuous discretizations, on the other hand, potentially offer a good compromise between accuracy and computational cost. We consider three different time discretizations, viz. a first-order time-continuous Galerkin method (TCG) in time, a second-order time-continuous Petrov-Galerkin method (TCPG) and a third-order discontinuous Galerkin method (TDG). We consider the efficacy of the spatial VMS discretization for the computation of fully-developed turbulent channel flow. We show that the present method leads to reduced resolution requirements compared to traditional LES approaches applying similar SGS models directly to all the resolved scales. The crucial parameter for obtaining reliable low-order statistics is found to be the large/small partition of the resolved scales. In particular, it is shown that when using simple eddy-viscosity models, the finite element basis functions capable of representing the basic dynamics of the near-wall coherent structures should be released from the direct influence of the SGS model. As space-time methods are necessarily implicit, a challenge is to ensure that the computations are carried out at reasonable cost. Therefore, we have conducted a detailed performance analysis to investigate the factors that influence the accuracy and computational cost of the proposed methods. For this purpose we consider again the turbulent channel flow. First, we examine the different time discretizations. It is demonstrated that the TCG method is not a competitive time discretization for the time steps of interest. The TCPG and TDG method, on the other hand, produce accurate and very similar results for relatively large time steps. However, the TDG method is considerably more computationally expensive as it uses twice the number of degrees of freedom compared to the TCPG method. Therefore, except for reasons of adaptation, the TCPG method is preferred here. Next, we compare the accuracy and cost of different spatial $hp$-resolutions for a similar total number of degrees of freedom. It is shown that the spatially higher-order methods lead to increased accuracy compared to a standard linear Galerkin method which cannot exploit the advantages of the present VMS formulation. However, higher-order methods are inherently expensive, as the computational work required within a time step scales quadratically with the number of finite element basis functions, while it scales only linear with the number of elements. Higher-order methods also have significantly denser system matrices resulting in rapidly increasing memory requirements with the order of the scheme. As the computational cost associated with higher-order methods is still relatively high, additional research areas are suggested for the goal of improving the method's cost efficiency.","space-time; finite element method; variational multiscale method; large eddy simulation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e0023223-0c81-433d-b65d-1270bb69915a","http://resolver.tudelft.nl/uuid:e0023223-0c81-433d-b65d-1270bb69915a","Ionospheric Modeling for Precise GNSS Applications","Memarzadeh, Y.","Teunissen, P.J.G. (promotor)","2009","The main objective of this thesis is to develop a procedure for modeling and predicting ionospheric Total Electron Content (TEC) for high precision differential GNSS applications. As the ionosphere is a highly dynamic medium, we believe that to have a reliable procedure it is necessary to transfer the high temporal resolution GNSS network data into the spatial domain. This objective led to the development of a recursive physics-based model for the regular TEC variations and an algorithm for real-time modeling of the medium-scale Traveling Ionospheric Disturbances (MS-TID). The research described in this thesis can roughly be divided into three parts. The main application of these developments can be found in Network RTK. Network-RTK is a technique based on a network of reference receivers to provide cm-level positioning accuracy in real time for users in the field. To get centimeter accuracy after a short (minutes) initialization period the ionospheric delay for the user's receiver needs to be predicted very precisely between the ionospheric pierce points of the reference receivers at the double difference level. Having the cm-level accuracy in the ionospheric interpolation is crucial for the carrier phase ambiguity resolution by the user. To achieve high precision in the ionospheric interpolation, regular and irregular variability of TEC in time and space should be taken into account. The regular TEC variation, which can reach several hundreds TEC units, is mainly a function of solar zenith angle. The irregular (or non-repeatable) variations are mainly wavelike effects associated with Traveling Ionospheric Disturbances (TID). Although TID effects on the TEC are of the order of 0.1 TEC unit, MS-TIDs, with a typical wavelength less than a few hundred kilometers, is one of the main obstacles for accurate spatial interpolation of ionospheric induced delays in a medium-scale reference GPS network. Since most of interpolation methods either use spatial linear (or quadratic) interpolation or fit a lower-order surface, the methods are not capable to model the phase-offset, caused by MS-TIDs, at distinct ionospheric pierce points. There are two major complications. Firstly, interpolation must be done at the double-difference level, which involves taking single differences between ionospheric delays for the same satellite between two different receivers, followed by differencing single differences for different satellites. This means that two different patches of the ionosphere are involved, each related to a different satellite, and each possibly associated with different TIDs. Secondly, for operational network RTK, a real-time strategy for TID detection and modeling is needed. In the first part the performance of several empirical ionosphere models for the regular TEC variation, such as Klobuchar, NeQuick, and the IGS Global Ionosphere Maps (GIM) are studied in the mid-latitude region using GPS data. Our results show that the GIM was able to correct the absolute slant ionospheric delay to better than 80% under different geomagnetic conditions of the ionosphere. The NeQuick model, which performed better than the Klobuchar model, could correct about 60% of the slant ionospheric delay. NeQuick is a real-time ionospheric correction model for the future European Galileo navigation system. A key input parameter for NeQuick is the effective ionization parameter (Az), which will be provided as a second order polynomial in the Galileo broadcast message to single-frequency users. The coefficients of the polynomial will be estimated daily from at least 20 permanent Galileo monitoring stations. As Galileo is under development, we propose an alternative approach for estimating Az using Global Ionospheric Maps (GIM). The main advantages of the alternative approach over the standard approach are: (1) the alternative approach is more reliable, because, each IGS GIM is based on data of up to 300 GNSS stations world-wide and each IGS GIM is the combination of results of up to four analysis centers, (2) the coefficients are more representative for all regions on the world because they are computed from a world-wide grid instead of about 20 distinct locations, (3) with the alternative procedure it is possible to provide Az in a different representation, for instance using a higher order polynomial, grid, or other function types, and (4) the computational effort is much smaller assuming the IGS GIMs have already been computed. In the second part a normal ionosphere is defined using Chapman's ion production theory to approximate the regular variability of the Earth's ionosphere. The normal ionosphere consists of lower and upper region. The lower region is formed in a photochemical equilibrium resulting in a Chapman layer. The upper region is formed in a diffusive equilibrium, whilst ignoring the geomagnetic field, resulting in a new Chapman like ionospheric layer. Integration of the continuity equation of the normal ionosphere over height leads to a Boundary Value Problem (BVP) for the temporal evolution of VTEC. Solution of the BVP results in a novel recursive model for the regular TEC variation as a function of solar zenith angle. The main motivation for developing this model is that the empirical models of the first part were either ill-suited or too complicated to model and predict the regular variation of TEC for high precision differential GNSS applications. The performance of the new model is tested at local and global scales using GIM. In general, despite the geomagnetic field was ignored, the cases analyzed show that the model gives a good overall representation of the regular variation of VTEC in the mid-latitude region under a geomagnetically quiet ionosphere. This is an important result that shows the potential of the model for a number of applications. Since the model has a recursive form it is ideally suited to use as time update equation in a dynamic data processing or Kalman filter. Another application is to use it for removing the geometry-dependent trend from time series of GPS-provided ionospheric delays to provide a pure TID observation, which is carried out in the third part of this thesis. In the third part, a new algorithm for the real-time detection and modeling of MS-TID effects is developed. In order to eliminate effects from large-scale TIDs, the algorithm uses between-receiver single-difference (SD) ionospheric delays in a medium scale GPS network. Although single-differencing also eliminates to some extend the geometry-dependent trend, the remaining part cannot be neglected. In this thesis, we fit the SD data to the recursive model which was developed in the second part of the thesis. Any wavelike fluctuations in the data with respect to the model are assumed to be from MS-TID effects. The detrended SD data are the main input of the algorithm. The algorithm consists of six steps: initialization, detection, scraping, cross-correlation, parameter estimation, and ending. A MS-TID is assumed to be a planar longitudinal traveling wave with spatially independent amplitude that propagates in an ionospheric patch. All characteristic parameters of the MS-TID wave (e.g. period, phase velocity, propagation direction, and amplitude) are considered to be time dependent, while the Doppler-shift caused by the satellite motion is taken into account in the estimation step. The performance of the algorithm is tested with GPS data from a network. Although real TIDs are not perfect waves, the algorithm was able to model (in time and in space) the MS-TID to a large extend. The performance was found to be comparable with the Kriging interpolation method. This is an important first result, in part because these two methods are based on different principles, but also because there is still room for improvement in our algorithm. With our physics based model it is possible to avoid the planar wave approximation and take the phase-offset of the wave into account, something which is not possible with Kriging.","ionosphere modeling; Traveling Ionospheric Disturbances; NeQuick model; Global Ionospheric Maps; Global Navigation Satellite Systems; precise GNSS positioning; Total Electron Content","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:58f16f99-afc1-4713-842e-562412583340","http://resolver.tudelft.nl/uuid:58f16f99-afc1-4713-842e-562412583340","Resistance Welding of Thermoplastic Composites: Process and Performance","Shi, H.","Benedictus, R. (promotor); Bersee, H.E.N. (promotor); Villegas, I.F. (promotor)","2014","Compared to thermoset composites, thermoplastic composites are drawing more and more attention by aircraft industries not only due to their excellent material properties but also due to their potentials to reduce cycle time and structure cost by using low-cost manufacturing technologies such as welding. Resistance welding has been regarded as one of the most promising welding techniques owing to the low energy consumption, simplicity of welding operation and capability for scaling up. Previous researches on resistance welding of thermoplastic composites are mainly focused on understanding the welding mechanisms and characterizing the welding qualities. The research work was aimed to gain deeper knowledge of resistance welding, in both micro-level and macro-level. In micro-level study, the specific properties that influence the welding quality were discussed, such as the surface properties of adherends, the weld line properties and the welding induced voids. In macro-level study, the emphasis was put on improving the current welding process, for both static resistance welding and continuous resistance welding. Micro-level study: 1. Resistance welding of woven fabric reinforced thermoplastic composites was investigated. Both the type of the majority fibres (warp yarns or weft yarns) and the apparent orientation of the majority fibres on the adherend surface were found to influence the failure mode and lap shear strength. Fibre sizing was found to be crucial for a good fibre-matrix adhesion, and therefore it was crucial for a good weld. 2. Other than fibre de-compaction, the residual volatiles inside the adherends was found to be a main cause of the voids in the joints for a welding process performed under a moderate welding pressure. Non-uniform void distribution was observed inside the joints, with void concentrations near the middle of weld overlap. The voids could be reduced by using pre-dried adherends or using a higher welding pressure. 3. A thinner weldline, usually obtained by using a thinner heating element, was found to be preferable to a thicker one. The relatively weaker welding quality near the edges of the joints was found to be a limitation of weld performance, but this could be improved by tailoring heat generation at the weld overlap or creating resin fillets near the edges. Micro-level study: 1. The possibility of using displacement measurement data for process monitoring and processing window definition was investigated, and it showed ability to detect voids generation and resin squeeze flow during welding and to construct processing windows. 2. The process of continuous resistance welding was analysed, and a model was developed to simulate the heat generation and heat transfer during welding.","thermoplastic; composites; welding","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:f5b66298-ed00-4abd-b47c-055c22ae488b","http://resolver.tudelft.nl/uuid:f5b66298-ed00-4abd-b47c-055c22ae488b","Self-Healing Corrosion Protective Sol-Gel Coatings","Abdolah Zadeh, M.","Van der Zwaag, S. (promotor); Garcia Espallargas, S.J. (promotor)","2016","Inspired by the state of the art and the recent advances in the field of self-healing corrosion protective coatings, the thesis entitled “Self-healing corrosion protective sol-gel coatings” addresses novel routes to self-healing corrosion protective sol-gel coatings via extrinsic and intrinsic healing approaches. The employed approaches aim at extending the service life of the coating and the underlying substrate by multiple damage closure/sealing and metal surface protection through incorporation of reversible tetrasulfide groups and inhibitor loaded containers respectively. Intrinsically healable hybrid organic-inorganic coatings containing reversible tetrasulfide groups were successfully developed and investigated using a combination of characterization techniques to address their healing kinetics and mechanism. Extrinsic healing concept was studied by encapsulation of corrosion inhibitors in smart micro- / nano-containers capable of on-demand leach out of the inhibitors to the damage site. Both routes explored have the potential to lead to future commercial self-healing coating systems.","self-healing; corrosion; coating; sol-gel","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Novel Aerospace Materials Group (NovAM)","","","",""
"uuid:00221eca-978c-4620-99c5-4759c4db726d","http://resolver.tudelft.nl/uuid:00221eca-978c-4620-99c5-4759c4db726d","Discrete Modelling of Plasticity and Martensitic Transformations","Shi, J.","De Borst, R. (promotor); Turteltaub, S.R. (promotor)","2009","","Martensitic transformation; Discrete dislocation plasticity; Transformation-induced plasticity","en","doctoral thesis","","","","","","","","2009-09-04","Aerospace Engineering","Engineering Mechanics","","","",""
"uuid:5db80592-96ce-4007-82eb-0a37708a7c01","http://resolver.tudelft.nl/uuid:5db80592-96ce-4007-82eb-0a37708a7c01","Static Strength of Riveted Joints in Fibre Metal Laminates","Slagter, W.J.","Rothwell, A. (promotor)","1994","","vliegtuigbouw; materialenkennis","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5e512d75-1890-48ae-9c05-05d31662da80","http://resolver.tudelft.nl/uuid:5e512d75-1890-48ae-9c05-05d31662da80","Thermal and structural performance of tow-placed, variable stiffness panels","Wu, K.C.","Gürdal, Z. (promotor)","2006","The structural response of two variable stiffness composite panels under thermal and mechanical loads are characterized using experiments and analyses. These panels are advanced composite structures where the fiber angle varies continuously within each ply, and are manufactured using an advanced tow placement system. Both variable stiffness panels have the same layup, but one panel has overlapping tow bands of varying thickness and the other panel has a uniform-thickness laminate. A conventional uniform-thickness panel with a straight-fiber [45]5s layup provides a baseline for comparison with variable stiffness panel performance. Measured shapes of the cured variable stiffness panels compare well with geometrically nonlinear analyses of an initially flat panel with a a-280F thermal load. The cured panels exhibit a linear strain response to moderate (approximately +60F) thermal loads. Large geometric imperfections in the cured variable stiffness panels require development of unique test fixtures to straighten the panel edges and provide appropriate structural test boundary conditions. When end shortening displacements are applied, the panels exhibit linear prebuckling and nonlinear postbuckling up to global failure. Variable stiffness panel buckling loads are up to 3.8 times the baseline panel value, with failure occurring at loads up to 53 percent higher than the baseline panel value. The variable stiffness panel structural response is predicted using geometric and materially nonlinear finite element analyses. These analyses incorporate mechanical and thermal prestresses, and measured imperfections. Strains and displacements from analyses with mechanical prestresses correlate well with measured results. While small during linear prebuckling, the nonlinear effects become increasingly important into postbuckling and approaching failure. The predicted baseline panel response also correlates well with test data.","Composite Structures; Tow Placement; Variable Stiffness; Nonlinear Analysis; Buckling; Postbuckling; Structural Testing","en","doctoral thesis","IOS Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c56e213c-82db-423d-a5bd-503554653413","http://resolver.tudelft.nl/uuid:c56e213c-82db-423d-a5bd-503554653413","Aircraft noise calculation and synthesis in a non-standard atmosphere","Arntzen, M.","Simons, D.G. (promotor)","2014","The atmosphere modifies the emitted sound waves of an aircraft during propagation and is therefore important in the calculation of noise contours or synthesis. Noise contours present the resulting noise levels on the ground and are, as such, often applied for regulatory purposes. Aircraft noise synthesis is a technique that allows to transform a calculated prediction into audible sound that can be experienced in a virtual reality environment. Noise synthesis techniques allow people to be subjected to aircraft, routes or procedures that are still being designed. This dissertation describes recent research to improve the modeling of atmospheric propagation effects in aircraft noise contours as well as aircraft noise synthesis. Multi-event noise contours are usually calculated with standardized models that take non-standard propagation into account in an empirical fashion. A propagation algorithm was developed to augment such a model. Signal processing steps can be applied to transform a source noise prediction into an audible result. Furthermore, such steps can be utilized to apply propagation effects to a source noise signal. For a non-standard atmosphere this is not trivial. The role of a non-standard atmosphere is described by a dedicated simulation framework developed in this dissertation. The framework is applied to a flyover to demonstrate the effects associated with multiple ray paths and shadow zones. Besides demonstrating non-standard atmospheric effects, the framework was used to create synthesized results of actual flyovers near an airport. Subsequently, a comparison between measured results and synthesized results was executed. Furthermore, a method was designed to include the effect of turbulence-induced coherence loss of the direct and ground reflected ray in noise synthesis.","aircraft noise; acoustic propagation; noise synthesis; auralization","en","doctoral thesis","","","","","","","","2014-12-04","Aerospace Engineering","Aircraft Noise & Climate Effects","","","",""
"uuid:938087b8-19b7-4bcb-9ffb-4757e11f8533","http://resolver.tudelft.nl/uuid:938087b8-19b7-4bcb-9ffb-4757e11f8533","Global-local Knowledge Coupling Approach to Support Airframe Structural Design","Wang, H.","Van Tooren, M.J.L. (promotor)","2014","The outsourcing that has taken place in the aircraft industry over the last few decades has created a globalized supply chain from and to a limited number of original equipment manufacturers (OEMs). This has led to multi-level design due to the shift from airframe subsystem design to suppliers. Increasingly OEMs focus on requirement allocation and definition of airframe subsystems and verification at a global level, whereas suppliers focus on the realization and improvement of airframe subsystems at the local level. Relying on a supply chain for innovative designs and builds can cause OEMs to have insufficient bottom-up knowledge about subsystem design, in particular, the innovative local designs, e.g. composites and new production methods, however, in the overall aircraft conceptual design phase, the analysis and evaluation of different subsystem designs, by OEM internally, rely heavily on assumptions and estimations which are usually based on statistical/empirical data. Although global designs can be quickly analyzed using assumptions and estimates, this risks costly design changes if the assumptions and estimations are proven incorrect in the later overall aircraft design phases. Suppliers who have detail-level knowledge should be involved early in the overall aircraft conceptual design phase, creating various local designs, and conducting more accurate analyses and evaluations of these designs. Early local design studies can help suppliers help OEMs to reduce the risk of design changes related to incorrect assumptions and estimations, and convince OEMs of the benefits of new material and new production methods. The objective of this research was to develop a design approach which can support suppliers to perform local design fast from which critical results, i.e. cost and weight, can be generated during the overall aircraft conceptual design phase. A fast airframe subsystem design is highly beneficial for suppliers wishing to increase their competiveness, providing fast response and being flexible in the overall aircraft conceptual design phase. It is also beneficial for OEMs to reduce the risk of design changes due to incorrect assumptions and estimations. Several issues in the current design process that hamper a fast study of airframe subsystems were identified in this research, some of which have to be addressed from the supplier’s side. 1) The dependency of suppliers on the OEMs to get coherent, consistent and timely design information, e.g. geometry and load cases, needed to start local design. This dependency causes suppliers wait until all the required information is available from the OEMs in the overall aircraft preliminary design phase. Therefore, the suppliers cannot proactively participate in the overall aircraft conceptual design, in which the airframe subsystem design relies heavily on assumptions and estimations. 2) The manual processes used by suppliers to update computer aided design (CAD) and analysis models to follow design changes at the global and local level. In the overall aircraft conceptual design phase, both the global and local design are not fixed yet and tend to change. Manually model updating at local design level takes significant engineering efforts, and hence slows down the supplier’s response to the changes in the global design. 3) There is a lack of multidisciplinary design optimization (MDO) capability and capacity at a local design level due to this lack of MDO knowledge and a lack of tools to build parametric product and process models. Therefore, in the short conceptual design phase, suppliers often just deliver a (few) feasible design solution(s) instead of a family of Pareto design solutions. To address these issues, and hence to increase supplier competitiveness, a global-local knowledge coupling approach is proposed, which comprises two modules at the global and local design level. The module at global design level is the cross-over, which is used as a substitute for global design and provides the inputs required for starting a local design. The cross-over is used to make the global and local designs concurrent in the early aircraft design phase. The module at the local design level is a set of parametric product and process models of airframe subsystems used to automate repetitive design actions at local design level, such that the analysis and evaluation of subsystem designs can be quickly performed. Knowledge based engineering (KBE) is adopted to implement the two modules for two main purposes: 1) parameterization of product models that allows automatic model (re)generation; 2) automation of pre-processing to prepare inputs for disciplinary analysis tools. Multidisciplinary design optimization is used as the technical implementation mean of the proposed approach to automate the process of finding an optimal design for a complex airframe subsystem. Three demonstration systems are developed, each of them formed as a design framework, called the Airframe Design and Engineering Engine (ADEE), which is a specialized Design and Engineering Engine (DEE). The design and engineering engine (Tooren, 2003) is a MDO system aimed at supporting and accelerating the design process of complex products, through the automation of non-creative and repetitive design activities. The verification design systems are the fuselage ADEE, the fuselage panel ADEE and the movable ADEE. One of the main contributions of this research is to identify the issues in the airframe design process which involves OEM and suppliers, and how these issues can be solved for quickly performing local design in the aircraft conceptual design phase. Another contribution lies in the development of the global-local knowledge coupling approach and its demonstration systems for the new design approach, which provide tools and methods to address these issues. Each verification tool is an ADEE, which is supported by KBE to perform global design and local design in an automatic fashion, such that cross-over can quickly generate the required inputs for local design and the local design module can quickly generate and analyse various subsystem design variants. The fuselage ADEE is used to address issue 1 by increasing design independence for panel suppliers The fuselage ADEE is implemented as a cross-over, in which finite element analysis (FEA) based weight estimation is developed to capture the effects of material and structural layout on fuselage weight. The global knowledge is captured in the cross-over, including the knowledge of how to generate fuselage outer mould line (OML) and knowledge of how to perform disciplinary analysis such as load calculation and structural analysis using FEA. The ADEE is validated using data from fuselages of conventional aircraft such as the ATR 42, Fokker 100, Boeing 737-200, Airbus A320-200 and Airbus A300B2. The fuselage ADEE is also used to estimate fuselage weight of a joint wing aircraft. The fuselage panel ADEE is used to address issue 2 by automating repetitive model (re)generation for local design The fuselage panel ADEE is the local design module of the global-local knowledge coupling, which comprises a parametric panel product model and disciplinary analysis models, i.e. structural analysis, cost estimation and weight evaluation models. The fuselage ADEE is a cross-over which provides inputs for the fuselage panel ADEE. A KBE-enabled parametric panel product model is implemented in the fuselage panel ADEE to model various configurations of fuselage panels flexibly, which are composed of skin with multiple layers and back-up structural members, such as frames and stringers. These structural members are modeled based on the OML generated by the fuselage ADEE. The structural analysis uses global-local FEA in which a global FE model is obtained from the cross-over to predict the overall fuselage behavior, whereas a refined FE panel model is built for investigating panel behavior. The local panel process knowledge is captured in the panel ADEE so as to automate the panel modeling, structural analysis, parametric bottom-up cost estimation and weight evaluation. Using the accelerated local panel design process, the local panel design can quickly respond to the change of global design, while the model consistency between global and local levels can be guaranteed. The movable ADEE is used to address issue 3 by automating repetitive design actions in the MDO process The movable ADEE is developed to perform cost/weight multi-objective optimization of movable structures, e.g. rudders and elevators, including large topology variations of the structural configuration. The KBE-enabled modelling module of this ADEE is able to model very different product configurations and variants and extract all data required to feed the weight and cost estimation modules, in a fully automated fashion. The weight estimation method uses FEA to calculate the internal stresses of the structural elements and an analytical composite plate sizing method to determine their minimum required thicknesses. The manufacturing cost estimation module was developed on the basis of a cost model available in the literature. The capability of the framework is successfully demonstrated by designing and optimizing the composite structure of a business jet rudder. The study case indicates that this ADEE is able to find the Pareto optimal set for minimum structural weight and manufacturing cost quickly. The demonstration systems developed demonstrate that the global-local knowledge coupling approach can support suppliers wishing to perform fast airframe subsystem design in the overall aircraft conceptual design phase.","","en","doctoral thesis","","","","","","","","2014-12-24","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:680a3181-2062-4923-be05-2c16ee1efa60","http://resolver.tudelft.nl/uuid:680a3181-2062-4923-be05-2c16ee1efa60","Broadband Liquid Dampers to Stabilize Flexible Spacecraft Structures","Kuiper, J.M.","Gill, E.K.A. (promotor)","2012","Mass-spring and liquid dampers enable structural vibration control to attenuate single, coupled lateral and torsional vibrations in diverse structures. Out of these, the passively tuned liquid damper (TLD) class is wanted due to its broad applicability, extreme reliability, robustness, long life time and ease of manufacturability. In this PhD thesis, the theory, design, verification and validation of multi-mode TLDs in terrestrial and mainly spacecraft (S/C) applications have been studied. The most challenging TLD design of the type “tube-with-endpots” was the Chinese meteorological FY-2 S/C nutation damper in the 90s. The extreme performance requirements like the 0.5” residual nutation damping angle implied an extended test program which led to refined insights in the recursive calibration method and limiting damping performance. The test analysis results and the involvement in the in-orbit analysis of the Ulysses S/C nutation anomaly in the same period, led the author to the idea of a multi-mode TLD system. The concept was proposed and successfully applied in the Cluster S/C for the effective damping of both nutation and coupled wire boom (antenna) oscillation modes. To come that far, the essentials of spacecraft dynamics and its control required an extension of the liquid flow models and an appropriate TLD design methodology to include multi-mode excitations. The TLD key performance parameters are the dissipation rate, residual damping angle and the resonance frequency which is directly related to the effective damping length. This parameter used to be obtained by an educated guess on basis of test heritage. The existing practical design rules, however, were overruled by new insights which are based on the latest scientific results from fluid mechanics. This knowledge and the extensive analysis of all available TLD damping performance tests resulted in a new refined methodology to estimate the effective damping length properly. The eventual value, however, must still be determined via recursive calibration cycles but better initial estimates reduce the required test times significantly. The residual damping angle is limited by the TLD endpot behavior which is determined by the physics of the liquid meniscus interaction with the endpot wall. Though the TLD design is characterized by a very low residual angle with almost zero dead-band, the very limit is not clear. This issue was investigated using multiple models and experiments whilst the state-of-the-art in the scientific literature from nano-tribology and wetting transitions on biomimetic surfaces was explored. Test refinements are proposed to decrease damping fluctuations and extend the low angular test range. Although, the limiting angle is not known, there is strong evidence that the limits can be extended beyond the 0.1” flight value. The early design phase of the broadband Cluster TLDs in 1991 and the TLD developments up to 2012 were studied. Moreover, the spin-stabilized magneto-spherical S/C Bepi-Colombo, Cluster, RBSP, DICE, Themis and FAST are compared which confirm the applicability of the multi-mode TLD concept. The study of the generic theory of wire boom oscillations, gyroscopically coupled to the S/C hub spin and nutation modes, resulted in a new harmonized parameterization and derived equations. The Cluster TLD system with in addition the internal wire boom damping enable the boom deflection limit and its damping time constant to be design parameters. On basis of this knowledge, a recursive bottom-up TLD design methodology was developed. The stability study including the wire boom composition made clear where the limit of multi-mode modeling is reached and breadboard experiments and practical engineering trade-offs are required. The optimal wire boom deployment strategy using the multi-mode damping principle was analyzed. At small angular deflections, however, material artifacts and anelastic flexure dominate and only dedicated engineering tests can clarify these issues. The current status of the TLD design was investigated by comparing the RBSP S/C [2012] ring TLD and the Cluster S/C [2000] endpot TLD designs. The combination of the Cluster TLD bottom-up design methodology with the 9 degrees of freedom RBSP top-down model completed the model base for the design of multi-mode TLDs in flexible S/C. The RBSP TLD suffers with considerable angular off-sets and inrush time constants which are not accounted for in the RBSP model. The Cluster TLD design, however, lacks these artifacts. RBSP S/C flight validation data, however, are not yet available. The nutation related Cluster flight data validate the TLD model predictions firmly within the requirements. This renders an indirect but incomplete prove of the effectiveness of the TLD system design. It is hard, however, to trace and validate the designed multi-mode performance itself. It is, therefore, of great scientific value to obtain Attitude Determination and Control System flight data. A successful TLD development requires risk mitigation as an essential part of systems engineering (SE). An inventory of boundary conditions was made thinking ahead for production and project cost escalations. In the high-tech industry, however, there is little focus on a scientifically based bottom-up SE approach though such effort does pay off. It was one of the quests of this thesis to prove the added value of such an investment. As a result, the developed methodologies do contribute to a profound SE approach in the development of multi-mode TLDs. The space qualified broadband TLD design with endpots is an excellent choice for use in future spin-stabilized S/C with wire boom configurations. The results of the PhD thesis enable the extreme refinement of the given damper concept. Market research and the allocation of dedicated solutions are a way towards valorization. Terrestrial spin-offs in the engineering fields of refined (ultra) centrifuges, pulsating industrial piping systems, windmills, earthquake control of building structures, shipbuilding and bridge stabilization offer the best valorization opportunities in short terms.","Spacecraft ADCS","en","doctoral thesis","","","","","","","","2015-11-25","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:b1abe278-bb42-481b-bc5b-7af53424bc75","http://resolver.tudelft.nl/uuid:b1abe278-bb42-481b-bc5b-7af53424bc75","Aerodynamics of flapping-wing Micro-Air-Vehicle: An integrated experimental and numerical study","Deng, S.","Bijl, H. (promotor)","2016","The interest in Micro Air Vehicles (MAVs) has stimulated continuous research activities, in view of their potential in civilian and military applications. An autonomous MAV with dedicated onboard sensors would be capable of executing mission in closed environments, such as surveillance, in door inspection in support of rescue operations and information gathering. Flapping wing MAV (also referred to as ’ornithopter’), which is the most intriguing type in the MAV family is often inspired from biological examples has triggered attention due to their outstanding manoeuvrability and flight capability at the low Reynolds number regime. Like natural flyers, flapping wing MAVs are usually equipped with a single or multiple pairs of flexible wings to generate both thrust and lift at the same time. Compared to the other locomotion, the flappingmotion benefits from a number of specific unsteady lift enhancement mechanisms. This thesis performs an integrated experimental and numerical study in order to explore the aerodynamic behaviour associated with flapping wing MAVs. The study is hereby divided into twofold: (1) Experimentally investigate the aerodynamic characteristics of flappingwingMAV, using state-of-the-artmeasurement techniques; (2) Develop a novel numerical methodology with particular focus in simulating flapping wing aerodynamics. For the experimental study, theDelFlyMicro was employed as the testbed in this thesis. The DelFly Micro uses an X-wing configuration which performs the clap-and-fling mechanisms three times during each flapping period and thus will result in complex flow behaviour. The aerodynamic characteristics were evaluated by means of extensive force production and power consumption measurements. The aero-structural effect of the DelFly Micro is fist investigated by means of a vacuum test, where the aerodynamically associated thrust component and different deformation patterns in air and in vacuum were addressed. Subsequently, the effect of wing properties, including flapping frequency, flexibility and wing aspect ratio are also examined in terms of thrust production, power consumption and propulsive efficiency. To better understand the aerodynamic force generation with respect to the flow structures, flow topology was visualized by Particle Image Velocimetry (PIV) techniques for the DelFlyMicro in both hover and forward flight configurations. The PIV measurement in the vicinity of the DelFly Micro revealed the formation, evolution of the vortical structures on the wing surface during flapping motion. A jet flow behaviour was revealed at all-time instants is induced by the clap and fling event. Three-dimensional flow structures in the wake of DelFly Micro were visualized by two reconstruction strategies: (1) a spatial reconstruction using Kriging regression with local error (can be regarded as the measurement uncertainties) estimates; (2) a temporal-spatial reconstruction based on the Taylor’s hypothesis of frozen flow. Two dominate structures generated during the instroke and outstroke alternatively shed from the wings which are quite isolated from each other for both hovering and forward flight configurations. In view of the facts that numerical simulating for flapping wing application is difficult due to the inherently large displacement during the flight. Particularly for the clap and fling event which is the most extreme situation would challenge the conventional dynamic mesh deformation techniques. A deformable mesh strategy was developed in this thesis with a specific purpose to simulate the flow with multiple bodies undergoing arbitrary large motion. The dynamic mesh strategy uses a hierarchical overset grid where the mesh quality and resolution can be independently controlled. Additionally, the deformation of the body is achieved by means of a RBF-based mapping mesh deformation technique which is proved to be efficient and robust in terms of CPU time and grid quality. The developed dynamic mesh method was embedded in an in-house programmed URANS solver and further used to simulate the DelFly II flapping wing MAV. The vortical structures demonstrate very complex flow behaviours associated with the DelFly II flappingwingMAV. Comparison between the numerical and the experimental results indicates that the numerical solver can provide a quantitative prediction of the unsteady aerodynamics of the flapping-wing MAV in terms of aerodynamic force production and flow structures.","flapping wing; Micro Air Vehicle; aerodynamics","en","doctoral thesis","","","","","","","","","Aerospace Engineering","AWEP","","","",""
"uuid:ba041d73-c9a3-4ead-956d-536965c41452","http://resolver.tudelft.nl/uuid:ba041d73-c9a3-4ead-956d-536965c41452","An experimental and analytical investigatin on the fatigue behaviour of fuselage riveted lap joints","Müller, R.P.G.","Schijve, J. (promotor); Vogelesang, L.B. (promotor)","1995","","fatigue; riveted lap joint; squeeze force; Glare3; residual stresses","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1fb3b77b-3ad0-4733-bc5e-39cf838dc840","http://resolver.tudelft.nl/uuid:1fb3b77b-3ad0-4733-bc5e-39cf838dc840","Acoustic formulations for aeronautical and naval rotorcraft noise prediction based on the Ffowcs Williams and Hawkings equation","Testa, C.","Van Tooren, M.J.L. (promotor); Gennaretti, M. (promotor)","2008","","aeroacoustics; hydroacoustics; scattering; rotors; propellers","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8313a3bd-701c-458a-bf99-e819e1276084","http://resolver.tudelft.nl/uuid:8313a3bd-701c-458a-bf99-e819e1276084","Efficient uncertainty quantification in computational fluid dynamics","Loeven, G.J.A.","Bijl, H. (promotor)","2010","When modeling physical systems, several sources of uncertainty are present. For example, variability in boundary conditions like free stream velocity or ambient pressure are always present. Furthermore, uncertainties in geometry arise from production tolerances, wear or unknown deformations under loading. Uncertainties in computational fluid dynamics (CFD) simulations can have a significant impact on the computed aerodynamic performance. Since CFD simulations are computationally intensive, an efficient uncertainty quantification approach is required. The main objective of this research is to obtain an efficient approach for uncertainty quantification in CFD simulations. This was achieved by focusing on efficient uncertainty propagation and the practical applicability to a wide range of test cases. The Probabilistic Collocation method was developed as an efficient non-intrusive uncertainty propagation method. It is based on the polynomial chaos framework and shows spectral convergence with respect to the polynomial chaos order. Its effectiveness was demonstrated on several flow cases using a commercial CFD solver. For cases with a discontinuous response or involving long time integration, modifications of the Probabilistic Collocation method were used to efficiently propagate the uncertainties. A Multi-element formulation was successfully applied to capture the discontinuous response of a stall flutter problem. Furthermore, a time-independent parameterization was used to efficiently propagate uncertainties in case of vortex shedding behind a circular cylinder, which required long time integration. Geometric uncertainties were shown to have a significant influence on the aerodynamic performance. Since geometric uncertainties affect the shape, a new computational grid should be computed for every collocation point in the Probabilistic Collocation method. To efficiently treat geometric uncertainties in CFD, a grid deformation technique was used. Most CFD simulations in this thesis involved solving the Reynolds-averaged Navier-Stokes equations. This required a turbulence model to close the system of equations. Turbulence models often contain several parameters that are tuned to computed or measured simplified flow problems, which introduces uncertainty in the model. Uncertainty quantification was applied to the parameters of the k-? turbulence model in combination with wall functions in the cases of flow over a flat plate and flow around a NACA0012 airfoil. The drag coefficient showed a coefficient of variation of 3-4% for both cases. The wall function parameters ? and C and the model parameter C? proved to affect the solution most. General conclusions require more test cases, like a shear layer and an expanding jet. Compressor rotors are components of a gasturbine that are highly sensitive to operational and geometrical uncertainties. Operational uncertainties like static outlet pressure and the total pressure profile at the inlet of the rotor were considered. The Probabilistic Collocation method was validated using a Monte Carlo simulation using 10,000 Latin Hypercube samples. It was shown that the mass flow was most sensitive to the uncertainty in the total pressure profile at the inlet. Multiple uncertainties were shown to be effectively handled using a two-step approach. The first step was a screening of the parameters. A sensitivity analysis was used to identify the most important parameters of the problem. Here it was assumed that all parameters are independent and have no combined effects. Secondly, the probability density functions of the most important parameters are propagated using the Probabilistic Collocation method. The Probabilistic Radial Basis Function approach was developed as an alternative efficient approach for multiple uncertain parameters. To obtain an accuracy of 0.01-0.001 for the mean and variance, the CFD test cases required 10-35 support points for 3 uncertain parameters. Close agreement between the Probabilistic Radial Basis Function approach and a Monte Carlo simulation using 10,000 Latin Hypercube samples was shown for flow around a RAE2822 airfoil with three uncertain parameters. It can be concluded that the Probabilistic Collocation method and adapted versions are capable of efficiently propagating uncertainties in CFD simulations. The development of the Probabilistic Radial Basis Function approach provided an efficient alternative for cases with multiple uncertain parameters. From the test cases it became clear that there is not a single method that is most efficient for all possible cases. Uncertainty quantification increases the reliability of CFD computations, since the effect of uncertain parameters on the output of interest is quantified. It was shown that small coefficients of variation of uncertain parameters can lead to a significant variability of the aerodynamic performance. Taking uncertainties into account in CFD simulation is therefore of great importance and with the current state of technology feasible for many real world applications.","Probabilistic Collocation; Stochastic Collocation; Polynomial Chaos; Computational Fluid Dynamics; Uncertainty propagation; Uncertainty quantification; Aleatory uncertainty; Parametric uncertainty","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:8c66e280-f5c5-416a-9ad2-cbcf23e9b14a","http://resolver.tudelft.nl/uuid:8c66e280-f5c5-416a-9ad2-cbcf23e9b14a","Mesostructure of Concrete - Stereological analysis and some mechanical implications","Zheng, J.","de Borst, R. (promotor)","2000","","","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7614ab4e-5730-404a-9592-cecfe19535a9","http://resolver.tudelft.nl/uuid:7614ab4e-5730-404a-9592-cecfe19535a9","Mechanical and vibro-acoustic aspects of composite sandwich cylinders","Yuan, C.","Beukers, A. (promotor); Roozen, N.B. (promotor); Bergsma, O.K. (promotor)","2013","Designing a fuselage involves many considerations such as strength and stability, fatigue, damage tolerance, fire and lightning resistance, thermal and acoustic insulation, production, inspection, maintenance and repair. In the background of the application of composite sandwich structures on the aircraft fuselage, the focus of the thesis is to investigate the vibration and acoustic behaviours of sandwich structures. As a preliminary design of aircraft fuselages, a sizing work of sandwich cylinders was conducted with respect to the strength and stability. FE models for the buckling prediction of the sandwich cylinder were validated with the analytical expressions. Under a typical flight loading, the sizing results of a sandwich cylinder and a laminated cylinder were compared and it was found that the mechanical efficiency of the sandwich cylinder is comparable to that of the traditional stiffened cylinder. Subjected to the diffuse acoustic field, the sound transmission loss (TL) of composite sandwich cylinders was investigated using an analytical method and the Statistical Energy Analysis (SEA) method at 100-16000 Hz. The SEA method showed a good agreement with the analytical method. The parameters, including the fibre orientation, facing materials, cylinder geometry, core thickness, sandwich layup and core shear stiffness, were studied for their influences on the TL of cylindrical structures. A uniform laminated, a stiffened and a sandwich cylinder with the equivalent mass were compared for the sound insulation performance. The laminated cylinder had the largest TL below the coincidence frequency and the sandwich cylinder had the largest TL above the coincidence frequency. The structural velocities and noise reductions of laminated and sandwich cylinders were experimentally tested at 1-4000 Hz under a point acoustic excitation, and a mechanical excitation respectively. The wave propagation in the sandwich structure was compared with that in the laminated structure, as an explanation of the noise reduction difference of the two structures. As the coincidence frequency plays an important role on the sound transmission, influence parameters of the coincidence frequency of sandwich structures were also studied. To investigate the vibro-acoustic performance of sandwich structures under different kinds of external excitations, the FEM/BEM numerical method was used to analyze the noise reduction of sandwich cylinders at low frequencies. Under a force excitation, some parameters including the core shear stiffness, sandwich layup, core thickness and facing orientation were studied for their influences on the sound transmission. Results showed that there exist optimal values for these parameters to achieve the best sound insulation performance. Therefore, an efficient optimization technique using the acoustic transfer vector (ATV) and the genetic algorithm (GA) was applied to optimize a typical sandwich cylinder for the best noise insulation. In addition, taking a fuselage section as an example, a multi-objective optimization (weight & noise insulation) was conducted considering the mechanical constraints under flight load cases. The noise control treatment such as the addition of absorption layers is one of the common methods for the noise control of the transport vehicles. Thus the sound transmission of sandwich panels with open-cell foam was studied. The transfer matrix method (TMM) was used for the TL prediction of sandwich panels with porous foams. This method was validated by experimental results. A sensitivity study of the flow resistivity, tortuosity and porosity on the TL of sandwich panels was conducted. Then four kinds of absorption materials were studied for their influences on the TL of sandwich cylinders. Finally the TLs of a stiffened cylinder and a sandwich cylinder were compared in case of addition of absorption layers. As the damping plays an important role on the vibro-acoustic behaviors of sandwich structures, the damping properties of composite sandwich structures were studied using the modal strain energy (MSE) method and experimental measurements. The hysteresis method and the half power method were used for the damping measurement. Compared to the facing, the cores usually have much higher damping and they make the main contribution on the sandwich damping. Therefore the material damping properties of two kinds of foams (PMI & PVC) were measured at low frequencies using the hysteresis method. The measured results have been validated by numerical models. The damping of the PVC foam were also measured using the half power method and results showed a good agreement with those measured using the hysteresis method. For the damping prediction of sandwich structures, the MSE method was verified by the measurements using the half-power method. Finally, the effects of the core thickness and core properties on the damping of sandwich structures were studied.","fuselage; acoustic and vibration; sandwich cylinder; damping; boundary element method; finite element method","en","doctoral thesis","","","","","","","","2013-07-08","Aerospace Engineering","Composite design and production","","","",""
"uuid:6258fd96-2f6f-4cda-9c4a-a6dc7d981185","http://resolver.tudelft.nl/uuid:6258fd96-2f6f-4cda-9c4a-a6dc7d981185","Aeroelasticity of large wind turbines","Holierhoek, J.G.","Van Holten, Th. (promotor)","2008","","wind energy; wind turbine; aeroelasticity; flutter","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3e1b8e7f-44b6-4361-9f92-7962b65a051e","http://resolver.tudelft.nl/uuid:3e1b8e7f-44b6-4361-9f92-7962b65a051e","Design of fibre reinforced composite panels for aerospace applications","Van Bladel, P.G.","Rothwell, A. (promotor)","1995","","vliegtuigbouwkunde; CAD","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:52fcfcee-d1ae-477a-aded-72f2f04270ff","http://resolver.tudelft.nl/uuid:52fcfcee-d1ae-477a-aded-72f2f04270ff","Development and application of a computer-based system for conceptual aircraft design","Bil, C.","Torenbeek, E. (promotor)","1988","","","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a6d75095-1908-472a-9d7b-cfdf313908fd","http://resolver.tudelft.nl/uuid:a6d75095-1908-472a-9d7b-cfdf313908fd","Design and evaluation of dynamic flight test manoeuvres","Mulder, J.A.","Gerlach, O.H. (promotor); Eykhoff, P. (promotor)","1986","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b91d9697-d800-417b-bb7e-c5adb00c5e2b","http://resolver.tudelft.nl/uuid:b91d9697-d800-417b-bb7e-c5adb00c5e2b","Smart Wind Turbine: Analysis and Autonomous Flap","Bernhammer, L.O.","Van Kuik, G.A.M. (promotor); Karpel, M. (promotor); De Breuker, R. (promotor)","2015","Wind turbines convert kinetic energy of the wind into electrical energy. Unfortunately, this process is everything but constant, as the wind source shows large fluctuations with high and low frequencies. This turbulence, together with the wind shear and yawed inflow, excites the turbine structure, thereby driving the loads and the design of turbines in general and blades in particular. In response to this, several control mechanisms have been applied to wind turbines since the generation of stall controlled machines in the 1980s. While collective pitch control was applied first, the control mechanisms have become more localised and act on individual turbine blades, rather than on the rotor as a whole. An advanced control scheme is termed 'smart wind turbine'. These type of wind turbine actively measures vibrations of its blades through a set of distributed sensors throughout the blades and then aims to counteract the vibrations using aerodynamic modifications around the blades' trailing edges close to the tips by means of control surface deflections. This thesis investigates two aspects of the smart rotor concept: the analysis of smart rotors and the design of an autonomous flap concept. For the analysis, a wind turbine analysis tool with special focus on smart rotors and controller implementation has been developed. This code, the Delft University Smart Wind turbine Analysis Tool (DU-SWAT), has been benchmarked not only against conventional wind turbine codes, but a comparison study with the first utility-scale smart rotor experiment, the Sandia National Laboratories Smart Rotor, was performed. The experimentally obtained eigenfrequencies of the test turbine matched closely those of the numerical study. The difference in the first eigenfrequency is 2.7% or 0.1 Hz (4.4 Hz experimentally, 4.5 Hz numerically). A second comparison step was a time domain analysis of the wind turbine response to a step deflection input of the flaps. For the tower response, the frequencies and the amplitudes of the numerical and experimental responses agree very well. For blade vibrations, an increase in damping in the numerical simulations is observed. While for low flap deflection amplitudes, up to 5 degrees, the response amplitude is predicted well. When high step deflections are modelled, the numerical simulations increasingly fail to accurately capture the dynamics of the turbine. In combination with the differences in damping, this leads to the conclusion that vortices, shed from the flap tips, interact with the larger tip vortices, possibly due to the proximity of the flaps to the blade tips. This inaccuracy of high flap deflection angles is however of limited importance, as it was demonstrated that the periodic (1P) load, the most dominant contributor to fatigue damage, could be alleviated effectively even with deflection angles up to 5 degrees. The individual flap controller has been tuned to the NREL 5MW reference turbine and has been used to study both fatigue and extreme loads according to the certification regulations. Failure-free cases were included in the analysis, and loads have been monitored throughout the turbine. The fatigue load reduction of the blade root bending moment of 24\% corresponds well with the findings of previous researchers. Besides this verification, it was also shown that the structural loads increase nowhere in the turbine, with the exception of the blade root torsional moment. Several other loads decrease, for example the tower torsion moments and the bending moments in the turbine shaft. The extreme load reduction is smaller than the fatigue load reduction. Still, the ultimate tip deflection and the ultimate blade root bending moment could be reduced by 7\% and 8\%, respectively. The moments in the tower are also reduced. Besides load alleviation, an additional functionality of the smart rotor was established. The flaps can be used to increase the power production of the turbine by responding to fluctuations in the wind speed and the delays in the adjustment of the rotor speed due to the rotor inertia. An intermediate step of the wind turbine analysis was the development of a suitable structural model. The developed structural dynamics model, which is based on modal equations of motion, is not limited to wind turbine structures, but rather applicable to a broad range of engineering problems concerning structural vibrations. The model closes the gap between modal reductions, which are typically used in linear vibration analysis, and non-linear geometry. For that purpose the structure is segmented and the segments are joined by rigid-body displacements in a co-rotational framework, which introduces geometric non-linearities. This allows modelling of the structural dynamics for large deformations, while maintaining linear stress information of the finite element model of all segments. The basic assumption underlying this approach is that the structural displacement is large, but the strains remain small, which is typically the case for slender structures such as wind turbine blades. The second major topic, which has been addressed in this dissertation, is the physical implementation of a flap system. The described flap system is fully autonomous and is mounted as a free-floating flap, which means that the flap can freely rotate around a hinge axis. The flap is controlled by a trailing edge tab and driven by servo actuators. The flap is mass underbalanced and aeroelastically unstable in interaction with one of the main structural modes. This renders the flap system highly responsive to control inputs, but also to external excitations. When vibrating, the kinetic energy of the flap is converted by electromagnetic harvesters into electric energy. This energy is either stored in a battery or used to power the sensors and the actuators. It was demonstrated that the instability of the flap dramatically increases the amount of harvested energy by, in case of the experiment, a factor of 225 for wind speeds just below and above the flutter speed. The flap system measures the vibrations through accelerometers. When unstable, the vibration amplitude is either limited by structural delimiters or can be actively controlled by the control system. It was shown, that the flap system can be self-sufficient during the controlled limit cycle oscillation. Id est the power produced during limit cycle oscillation is greater than the power consumed to keep the oscillation amplitude constant. The main advantage of the autonomous flap is its improved replaceability compared with non-autonomous ones. As it neither needs a connection to a central control unit and a power system, nor is an integral part of the wind turbine blades like seamless solutions, it can be exchanged easily in case of failure. In conclusion, smart wind turbines have a great potential to improve the cost efficiency by reducing loads for most turbine components as has been shown in this dissertation. This can be achieved using the novel flap concept, which helps, due to its plug-and-play nature, to reduce maintenance costs.","wind energy; aeroelasticity; structural dynamics; adaptive structures","en","doctoral thesis","","","","","","","","2015-10-12","Aerospace Engineering","Wind Energy/Aerospace Structures and Computational Mechanics","","","",""
"uuid:027701f4-ee7a-4217-89e2-df61f998a61b","http://resolver.tudelft.nl/uuid:027701f4-ee7a-4217-89e2-df61f998a61b","Vestibular adaption to an altered gravitational environment: Consequences for spatial orientation","Nooij, S.A.E.","Ockels, W.J. (promotor); Young, L.R. (promotor)","2008","Earth's gravity is an omnipresent factor in human life and provides a strong reference for spatial orientation. Changes in the prevailing gravity level, like the transition to weightlessness during space flight, affect spatial orientation and require adaptation of many physiological processes involving the vestibular system (sensitive to linear acceleration and thus gravity). As long as adaptation is not complete, this adaptation process may be accompanied by nausea, visual or self-motion illusions, and disorientation, as experienced by roughly 50% of all space travelers during the first days of spaceflight. Interestingly, the same symptoms can also be experienced on Earth, after sustained exposure to a higher gravitational load in a human centrifuge (i.e., >60 minutes at a level of 3 times Earth's gravity, 3G). And importantly, individual susceptibilities to these symptoms during space flight and following centrifugation are correlated. The finding that the transition from 3 to 1G can evoke the same symptoms as a transition from 1 to 0G indicates that it is not weightlessness per se that causes these symptoms, but that there seems to be a general mechanism for adaptation to an altered gravitational environment. In this thesis the paradigm of sustained centrifugation was used to study the vestibular effects of gravity transitions and the underlying adaptation mechanism. The experiments described in this thesis provided further evidence for a correlation between space motion sickness and sickness induced by sustained centrifugation: astronauts who were susceptible to space motion sickness during spaceflight also suffered from sickness after centrifugation. The role of gravity in the occurrence of the symptoms was underscored by the finding that, after centrifugation, dynamic head movements evoked nausea in susceptible subjects, but only when they changed the orientation of the head relative to gravity (i.e., pitch and roll when erect). In addition, nausea increased with the speed of the movements, the duration of the hypergravity exposure and the level of the applied G-load. Investigation of individual vestibular function parameters indicated that left-right differences within the vestibular system (i.e., differences in sensitivity) contributed to individual susceptibility. Investigation of various ocular responses depending on gravity learned that the eyes' spatial behaviour was less adequate after centrifugation. Furthermore, evidence was found supporting the hypothesis that the integration of sensory signals, required to obtain an adequate perception of gravity during dynamic head movements, was deteriorated. Because the perception of gravity is directly related to the occurrence of motion sickness, this can provide an explanation for the occurrence of these symptoms when tilting head movements are performed after centrifugation. The results of these studies therefore shed light on the mechanism underlying the consequences of gravity transitions. They have direct bearing on the application of artificial gravity during space flight, and can be relevant for astronaut training.","weightlessness; gravity; vestibular system; motion sickness; spatial orientation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f6a61773-4173-4728-a2e3-ce320228753a","http://resolver.tudelft.nl/uuid:f6a61773-4173-4728-a2e3-ce320228753a","Optical Coherence Tomography for Material Characterization","Liu, P.","Benedictus, R. (promotor)","2014","Optical coherence tomography (OCT) is a non-invasive, contactless and high resolution imaging method, which allows the reconstruction of two or three dimensional depth-resolved images in turbid media. In the past 20 years, OCT has been extensively developed in the field of biomedical diagnostics, while OCT in the non-destructive testing (NDT) field is lagging far behind. The aim of this thesis is to use OCT as a novel NDT technique for material structure characterization and damage detection. Besides an overview of the OCT fundamentals and developments, the thesis is mainly driven by three tasks: instrument design, signal processing, and applications. An integrated OCT system working at a wavelength of 1550 nm has been built. It combines time domain (TD) and Fourier domain (FD) OCT to make the both types of measurement available in one instrument. TD-OCT has the advantage of a large A-scan range and high SNR, while FD-OCT system has tremendous superiority in fast imaging due to no movement of the reference mirror. These two kinds of measurement can be implemented based on the user request in the developed hybrid OCT system, e.g. improved imaging depth or speed. In TD-OCT, the envelope detector was selected as the ideal method for the demodulation of each axial signal. A bandpass filter and 2D median filter are applied before and after demodulation, respectively, to reduce OCT system and speckle noise. In FD-OCT, raw data was first processed to remove the influence from the optical source and dark noise of the CCD detectors. It was then linearly resampled to convert to evenly spaced intervals of wavenumber, instead of wavelength. With an inverse Fourier transform, one depth profile was recovered and a cross-sectional image was constructed by accumulating a series of depth profiles. The quality of cross-sectional images can be further improved by merging multiple images with different pathlength offsets. The application of the designed OCT system was mainly focused on glass fiber composites and the microstructure of the specimens was displayed by either cross-sectional or volumetric images. Special attention was given to delamination growth in a glass fiber composite for wind turbine blade applications. The glass fiber composite was tested by incremental loading. Volumetric images obtained by OCT were further processed to reconstruct 3D crack surface profiles, from which a full field view of the delamination crack was given, providing substantial information for the study of crack growth in the composites. Additionally, the study explored the use of optical coherence elastography (OCE) for the deformation measurement of glass fiber composites, for the first time to the best of our knowledge. The developed OCE system based on speckle tracking was first evaluated by a test of ridge body translation. Then experiments were implemented for a set of glass fiber composites under tensile testing and three point bending. The results show that OCE can measure the internal displacements of a glass fiber composite in the range from a few micrometers to hundreds of micrometers. Besides, other applications are also presented in the thesis. These include defects and thickness measurement of polymer coating and the microstructure characterization of a wooden-panel painting. The results show the designed OCT system also has high potential for these alternative applications. Recommendations for further improvement to the OCT design and the applications are presented at the end of the thesis.","Optical Coherence Tomography; Non-destructive Testing; Glass Fiber Composites; Delamination","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:2fb59768-f1b7-4d45-8ffb-eb4342a473cf","http://resolver.tudelft.nl/uuid:2fb59768-f1b7-4d45-8ffb-eb4342a473cf","Numerical strategies for corrosion management: Spatial statistics and finite element simulation","Lopez De La Cruz, J.M.","De Borst, R. (promotor)","2008","The techniques presented in this thesis are focused to improve corrosion management by providing a better insight into the nature of corrosion. Spatial statistics and finite element simulations are applied to different corrosion patterns to study possible interaction among pits. In order to achieve reliable results different spatial techniques are implemented.","corrosion; spatial statistics; fem; pattern analysis","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:16240b62-c9bf-4c85-8049-796c32595935","http://resolver.tudelft.nl/uuid:16240b62-c9bf-4c85-8049-796c32595935","Bifurcation in Fluid Flow near a Boundary Surface; Bifurcatie in stromingen van vloeistof of gas in de omgeving van een begrenzend oppervlak","Boon, R.J.P.","Bakker, P.G. (promotor); Reyn, J.W. (promotor)","1997","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:cad038c6-1cdc-4ef7-a813-d7b4dfac8281","http://resolver.tudelft.nl/uuid:cad038c6-1cdc-4ef7-a813-d7b4dfac8281","On the asymptotic solution of wave propagation and oscillation problems","Burger, A.P.","Timman, R. (promotor)","1955","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:754f3ea9-e37e-4248-993f-6e0998f80aba","http://resolver.tudelft.nl/uuid:754f3ea9-e37e-4248-993f-6e0998f80aba","The calculation of turbulent reacting flows with a combustion model based on finite chemical kinetics","Vos, J.B.","Steketee, J.A. (promotor); Veldman, A.E.P. (promotor)","1987","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3b516cb3-33e6-433f-8cf3-bb0e9e9feae1","http://resolver.tudelft.nl/uuid:3b516cb3-33e6-433f-8cf3-bb0e9e9feae1","Aeroelastic model identification of winglet loads from flight test data","Reijerkerk, M.J.","Mulder, J.A. (promotor); Chu, Q.P. (promotor)","2008","Numerical computational methods are getting more and more sophisticated every day, enabling more accurate aircraft load predictions. In the structural design of aircraft higher levels of flexibility can be tolerated to arrive at a substantial weight reduction. The result is that aircraft of the future can be bigger, have better performance and less mass. The performance of an aircraft can be even further enhanced by the use of winglets or other wing tip devices. A more flexible structure in combination with larger dimensions can lead to substantial structural deflections. Due to these larger deflections, the interaction between the aerodynamics and structural mechanics is of increasing importance. Due to their outboard position, the aerodynamic performance of wing tip devices is obviously significantly influenced by the deformation of the flexible wing. Off course, a safe and reliable operational life of the aircraft has to be guaranteed and proven with adequate design calculations. The goal of this thesis was to develop an algorithm to enable the identification of flexibility effects on the outer wing within a manoeuvre loads context based on the Maximum Likelihood Method. The main difference with approaches of existing publications is that the models considered here are based on distributed local data rather than on the net effect on aircraft performance. While this requires the size of the specific models to be much larger, the identified models allow a much more detailed physical interpretation of the observed performance benefits or penalties of winglets or wing tip devices. There are many references that address the topic of aerodynamic performance of wing tip devices and also of winglets in particular. These studies are all based on either wind tunnel measurements or pure aerodynamic (CFD) analysis, thus valid for rigid aircraft. These studies are very important in understanding the complicated flow condition at the wing tip in order to arrive quicker at even more efficient designs. However, flight test measurements have shown that flexibility of the airframe has to be taken into account when predicting the (aerodynamic) loads on the winglet. An algorithm was developed that is able to identify the parameters in a nonlinear coupled aero-elastic manoeuvre loads model. The algorithm is based on the Maximum Likelihood method which is capable of solving even rank-deficient problems. This identification procedure is applied for a loads relevant industrial case using real flight test data. The identification procedure is performed five times using these in-flight measurements with modifications in the aerodynamic modelling on the wings and winglets. One model was developed that describes the nonlinear rigid behavior and could be optimised in an identification for a best fit to the flight test measurements. It was found that especially the local alpha-gradients on the winglet are much larger in this model as predicted by the corresponding results derived from the original aerodynamic database. These identified gradients were compared with the gradients determined from the CFD-simulations and it was shown that they correspond very well. The success of the identification of a specific model strongly depends on the structure of the model and the assumed initial values. The model must be sophisticated enough to capture/describe the phenomena contained in the measurements, however simple/small enough to enable its identification with the available computational resources. The identification algorithm from this thesis was shown to be a very good means to quantify model improvements during model development. Secondly, it can obviously be used to identify the most optimal values for the free model parameters.","flight test identification; flight loads analysis; winglets; wing tip devices; maximum likelihood; aeroelasticity; multi-disciplinary modelling","en","doctoral thesis","","","","","","","","2010-04-01","Aerospace Engineering","Control and Simulation","","","",""
"uuid:415fad86-a326-4898-a495-343b41ea033b","http://resolver.tudelft.nl/uuid:415fad86-a326-4898-a495-343b41ea033b","Influence of wind conditions on wind turbine loads and measurement of turbulence using lidars","Sathe, A.R.","Van Bussel, G.J.W. (promotor); Mann, J. (promotor)","2012","Variations in wind conditions influence the loads on wind turbines significantly. In order to determine these loads it is important that the external conditions are well understood. Wind lidars are well developed nowadays to measure wind profiles upwards from the surface. But how turbulence can be measured using lidars has not yet been investigated. This PhD thesis deals with the influence of variations in wind conditions on the wind turbine loads as well as with the determination of wind conditions using wind lidars. Part I of the thesis focuses on analysis of diabatic wind profiles, turbulence, and their influence on wind turbine loads. The diabatic wind profiles are analyzed using the measurements from two offshore sites, one in the Dutch North Sea, and the other in the Danish North Sea. Two wind profile models are compared, one that is strictly valid in the atmospheric surface layer, and the other that is valid for the entire boundary layer. The second model is much more complicated in comparison to the first. It is demonstrated that at heights more than 50 m above the surface, where modern wind turbines usually operate, it is advisable to use a wind profile model that is valid in the entire boundary layer. The influence of diabatic wind profiles under steady winds on the fatigue damage at the blade root is also demonstrated using the aero-elastic simulation tool Bladed. Furthermore, detailed analysis of the combined influence of diabatic wind profile and turbulence on the blade root flap-wise and edge-wise moments, tower base fore-aft moment, and the rotor bending moments at the hub is carried out using the aero-elastic simulation tool HAWC2. It is found that the tower base fore-aft moment is influenced by diabatic turbulence and a rotor bending moment at the hub is influenced by diabatic wind profiles. The blade root loads are influenced by diabatic wind profiles and turbulence, which results in averaging of the loads, i.e. the calculated blade loads using diabatic wind conditions and those calculated using neutral wind conditions are approximately the same. The importance of obtaining a site-specific wind speed and stability distribution is also emphasized since it has a direct influence on wind turbine loads. In comparison with the IEC standards, which generalize the wind conditions according to certain classes of wind speeds, the site-specific wind conditions are demonstrated to give significantly lower fatigue loads. There is thus a potential in reducing wind turbine costs if site-specific wind conditions are obtained. In this regard we then are faced with measurement challenges. The current industry standard for the measurement of wind speed is either the cup or the sonic anemometer. Both instruments require a meteorological mast to be mounted at the measurement site. For measuring the wind profile the instruments need to be mounted at several heights on the mast. To install a mast and set up these instruments is quite expensive, especially at offshore sites, where the cost of foundation increases significantly. Besides, there are problems with the flow distortion that have to be taken care of. In order to overcome these problems it would be ideal to have a remote sensing instrument that measures wind speed. Wind lidars are capable of doing that albeit with a price. Part II of the thesis deals with detailed investigations of the ability of wind lidars to perform turulence measurements. Modelling of the systematic errors in turbulence measurements is carried out using basic principles. Two mechanisms are identified that cause these systematic errors. One is the averaging effect due to the large sample volume in which lidars measure wind speeds, and the other is the contribution of all components of the Reynolds stress tensor. Modelling of turbulence spectra as measured by a scanning pulsed wind lidar is also carried out. We now understand in detail the distribution of turbulent energy at various wavenumbers, when a pulsed wind lidar measures turbulence. The lidar turbulence models have been verified with the measurements at different heights and under different atmospheric stabilities. Finally, a new method is investigated that in principle makes turbulence measurements by lidars possible. The so-called six beam method uses six lidar beams to avoid the contamination by all components of the Reynolds stress tensor. The theoretical calculations carried out demonstrates the potential of this method. In order to avoid averaging due to volume sampling, a different analysis method is required, which has not been investigated in this thesis. To summarize the entire thesis, it can be said that more work is required to ascertain the influence of atmospheric stability on wind turbine loads. In particular, comparing with the load measurements will go a long way in consolidating the understanding gained from the analysis in this thesis. If lidars are able to measure turbulence, there is a tremendous potential for performing site-specific wind turbine design and making the class based design of the IEC standards obsolete.","wind profiles; turbulence; wind turbine loads; lidar turbulence measurement","en","doctoral thesis","DUWIND Delft University Wind Energy Research Institute","","","","","","","2012-02-13","Aerospace Engineering","Wind Energy","","","",""
"uuid:44d6d877-cffe-4ec8-b594-6ce1a73f351a","http://resolver.tudelft.nl/uuid:44d6d877-cffe-4ec8-b594-6ce1a73f351a","The Residual Strength of Fibre Metal Laminates","Vermeeren, C.A.J.R.","Schijve, J. (promotor); Vogelesang, L.B. (promotor)","1995","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b07421b9-136d-494c-a161-b188e5ba1d0d","http://resolver.tudelft.nl/uuid:b07421b9-136d-494c-a161-b188e5ba1d0d","Investigations of the transonic flow around oscillating airfoils","Tijdeman, H.","Bergh, H. (promotor); Van Ingen, J.L. (promotor)","1977","Exploratory wind-tunnel experiments in high-subsonic and transonic flow on a conventional airfoil with oscillating flap and a supercritical airfoil oscillating in pitch are described. In the analysis of the experimental results, emphasis is placed upon the typical aspects of transonic flow, namely the interaction between the steady and unsteady flow fields, the periodical motion of the shock waves and their contribution to the overall unsteady airloads. Special attention is paid to the behaviour of the supercritical airfoil in its ""shock-free"" design condition. Moreover, it is discussed to what extent linearization of the unsteady transonic flow problem is allowed if the unsteady field is considered as a small perturbation superimposed upon a given mean steady-flow field. Finally, the current status of unsteady transonic flow theory is reviewed and the present test data are used to evaluate some of the recently developed calculation methods.","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b16aef8a-da41-4db5-aead-1b921e496485","http://resolver.tudelft.nl/uuid:b16aef8a-da41-4db5-aead-1b921e496485","Collapse behavior of imperfect sandwich cylindrical shells","Karyadi, E.","Arbocz, J. (promotor)","1998","","buckling; sandwich constructions; cylindrical shells","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:335a0b9e-c598-4c89-b22b-9feb46f1ba75","http://resolver.tudelft.nl/uuid:335a0b9e-c598-4c89-b22b-9feb46f1ba75","Goal-oriented-error estimation for hierarchical models of a different type","Cnossen, J.M.","Bijl, H. (promotor); Koren, B. (promotor); Bakker, P.G. (promotor)","2007","For the simulation of many physical processes, a collection of mathematical models with different level of sophistication is available. Such a collection is called a class of hierarchical models in which the hierarchy is determined by the level of sophistication of the models. In many such classes, solving a fine model is computationally costlier than solving a coarse model. Using the coarse model however, introduces a modelling error in the solution and hence in a quantity of interest. A new trend in computer simulations to reduce computational time but to meet a required accuracy is adaptive modelling. To drive an adaptive modelling process in which the accuracy of a quantity of interest is the goal, a goal-oriented modelling-error estimator is required. An approach to derive a goal-oriented modelling-error estimator is the Dual-Weighted Residual (DWR) method. The main question of this thesis is whether or not the DWR method is suitable for modelling error estimation in classes of hierarchical models in which the model equations are of a different type, i.e. when the models require different boundary conditions. For successful use of the DWR method, it is found to be essential to incorporate boundary residuals explicitly in the error estimator; especially for nonlinear problems where high-order boundary terms can be of significant magnitude.","Modelling error; goal-oriented error estimation; hierarchical models; dual-weighted residual method; adjoint approach; singular perturbation problems; convection-diffusion","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0ef02668-779c-41ad-8605-0ca69ca4157f","http://resolver.tudelft.nl/uuid:0ef02668-779c-41ad-8605-0ca69ca4157f","Modelling CCT-Diagrams for Engineering Steels under Neural Networks","Van der Wolk, P.J.","Van der Zwaag, S. (promotor)","2001","","neural network; steel; heat-treatment","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d6102658-c499-4dd0-8481-a39ae6f7cd09","http://resolver.tudelft.nl/uuid:d6102658-c499-4dd0-8481-a39ae6f7cd09","Computational Modelling of Masonry Creep and Shrinkage","van Zijl, G.P.A.G.","de Borst, R. (promotor); Rots, J.G. (promotor)","2000","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9e8e9c3a-edc3-49a0-ae6b-980bb2eea5e5","http://resolver.tudelft.nl/uuid:9e8e9c3a-edc3-49a0-ae6b-980bb2eea5e5","Heat Transfer in the Thick Thermoset Composites","Shi, L.","Benedictus, R. (promotor); Jansen, K.M.B. (promotor)","2016","Nowadays more and more large composites are used to replace the traditional metallic structural materials in the industries. However, for manufacturing the thick thermoset composites, the size not only influences the mechanical properties in the completed products, but also the core temperature overshoot generated during the curing reaction. This study is focusing on the heat transfer phenomenon in the thick thermoset composites during cure. A heat transfer coupled cure kinetic system was established to predict the temperature distribution in the composite. In this thesis, the research mainly consists of analytical modeling, numerical modeling and experimental validation. The results show that the analytical and numerical analysis agrees with the experiments well.","heat transfer; thick thermoset composites","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Structural Integrity & Composites (SI&C)","","","",""
"uuid:0a18a5e5-7109-4fab-97fb-b2a99d9f3726","http://resolver.tudelft.nl/uuid:0a18a5e5-7109-4fab-97fb-b2a99d9f3726","An Integrated Knowledge Based Engineering Mechatronics Modeling Approach to Support the Design of Unstable and Unmanned Aircraft","Tian, F.N.","Veldhuis, L.L.M. (promotor)","2015","The commercial transport aircraft industry is currently developing new “more electric aircraft” (MEA) designs in which various conventional mechanical, hydraulic and pneumatic power systems are replaced with electrically-based power systems. Their objective is to improve the overall flight performance by reducing the aircraft weight and by a lower overall energy requirement for the systems. The vision for the future is to ultimately replace all systems with electrical systems and even to replace a part of the fuel used as primary source of energy for the propulsion system by an electrical power supply and thereby to achieve either a hybrid electric aircraft (HEA) or even all electric aircraft (AEA) if permitted by future developments in battery technology. In recent years, many small scale electric aircraft were developed to demonstrate the AEA concept. It has been determined that although the MEA, HEA and AEA concepts reduce the overall complexity of the aircraft, it significantly increases the complexity of electrical and electronic systems (E/E systems) and their integration into the aircraft, introducing a new challenge for the aircraft design industry. Two specific categories of aircraft, currently in operation, face the same challenge. These categories are; (1) unmanned aerial vehicles (UAVs), which by nature have more electrical and electronic systems (E/E systems) on-board and require an automatic flight control system due to the absence of a pilot and (2) aircraft which are inherently unstable and therefore require automatic flight control systems for stabilization. These two aircraft categories can be classified as typical mechatronic products. E/E systems have a significant impact on the overall flight performance, directly determine the flying qualities of aircraft, and are critical for safety. Thus, these systems should be developed synchronously with the other traditional engineering domains such as aerodynamics, structures and propulsion. However, several challenges need to be overcome before this can be achieved effectively. Three specific challenges are identified and addressed in the current research study: The development of high fidelity multiphysics simulation models for analysis and development of the E/E systems is a complex, time consuming and multidisciplinary task that requires a large amount of manual work from simulation experts; The design of consistent automatic flight control systems for use throughout the entire flight envelope and for all aircraft weight and c.g. combinations is labor intensive and requires the availability of high fidelity multiphysics simulation models in the early design phases; The development of control software components is prone to errors due to inconsistencies between the description of the top level physical configuration, the control architecture and the associated software components. Traditional aircraft design methods which are largely dominated by the mechanical engineering domains are not suitable to synchronously design complex integrated E/E systems. Moreover, the conventional design process, which is sequential to a large extent, cannot support concurrent engineering requirements. Therefore, novel methods and tools to support the development of the E/E systems on-board aircraft are needed. The overall objective of this research study is to reduce the development time of aircraft with a high level of integrated E/E systems by automating the design process of the flight control systems, by creating more consistent control software through the entire design envelope. Besides a reduction in development time this will also improve the quality of the final (mechatronic) product. The three challenges described above will be tackled in particular. The novel methods and tools are based on the knowledge based engineering (KBE) approach. The KBE approach is highly suitable because it cannot only automate non-creative, repetitive design tasks done for example by simulation experts but also support for multidisciplinary design, analysis and optimization (MDAO). Compared to other existing KBE systems, the proposed system integrates the flight control system design with the physical design in three specific areas. First, in order to ensure a consistent design representation, the concept of a multiphysics information model (MIM) is proposed in order to integrate the design knowledge present from multiple engineering domains. The proposed MIM (a KBE system) defines objects with attributes to represent various aspects of physical entities (e.g., mass, inertia, geometry, material properties). Moreover, it uses functions to capture non-physical information, such as the control architecture, relevant test maneuvers, simulation procedures, etc. The problem of system coupling and interactions between disciplines involved are taken into account by the proposed KBE system in a knowledge acquisition process. Next, depending on the requirements, the proposed KBE system extracts necessary knowledge from the MIM which is needed for the development of a multiphysics simulation model, which is composed of a physical plant, flight control systems including the embedded control software and simulation configurations. By capturing the expertise of simulation experts, the proposed KBE system is able to automatically instantiate the multiphysics simulation models. This multiphysics simulation model can be used to evaluate the flight control systems in operation practice throughout the flight envelope, for example when performing maneuvers. Altogether, the MIM enables rapid development of high fidelity multiphysics simulation models for analysis and development of the flight control systems. Second, in order to evaluate the inherent flying qualities of unstable aircraft in a simulation environment, an automatic flight control system is required. For this purpose, model based inversion control is applied. This method has the advantage that tuning is not required. The techniques, processes and knowledge required to develop a model based control system based on the (nonlinear) multiphysics simulation model are captured by the KBE system. Model based inversion control has its disadvantages when implemented on real-life aircraft. For the final design solution developed by the framework, which will enter the detailed design phase and which will ultimately be produced, other control methods and architectures can be developed, more appropriate for a real-life situation. Such a control system will only have to be tuned and developed once in contrast to the thousands of designs evaluated in an MDO framework. This application of model based inversion control is considered new. Third, in order to avoid errors in the embedded control software as a result of manual programming activities, the dependencies of parameters in the software on physical parameters of an evolving design and the high complexity (thousands of lines of code), control software components of flight control systems should ideally be developed in an automated fashion. The proposed KBE system has the ability to generate consistent control software components. The system extracts the variable definitions and values from physical configurations and control architecture from the information model to specify the variables in the software components. In addition, the system divides software components into basic elements and writes them into strings, which can, in principle, be any computer language. When the top level configuration and control architecture changes, the proposed KBE system can operate the basic elements in specific order and automatically create new software components by capturing the expertise from software engineers. Summarizing, because both the geometry model and multiphysics simulation model including flight control system are obtained from one source, the MIM links the physical modeling and control system design with the development of software components with respect to data and topology structure. A multirotor UAV configuration is used as test case to demonstrate the novel methods and tools described above. This is an inherently unstable configuration with a wide range of applications. A computational framework is developed which enables the conceptual/preliminary design and optimization of this typical mechatronic product. The proposed KBE system automatically creates thirty thousand designs of multirotor UAVs with different topologies and then evaluates each solution by automatically simulating five test maneuvers and by checking twenty-two constraints. Results show that the proposed KBE system can automatically generate multiphysics simulation models to support the multidisciplinary analyses not restricted to the mechanical domain but also applicable for evaluation of flight control systems and other domains. Even though different design solutions can have a highly different topology, automatic flight control systems based on the model inversion control method are created automatically for each design solution, enabling the evaluation of the inherent flying qualities of the unstable aircraft configuration. Furthermore, within the framework, design processes are automatically completed from the initial definition of top-level aircraft requirements, to the design and optimization, and finally down to selecting feasible solutions. The approach demonstrated leads to: a reduction in manual work, improved quality of the final solution, and consistent control system and software components. Key to the MIM concept is that it focuses on capturing the intrinsic properties of physical systems by the KBE approach and a specific format of representation is avoided. Although the current research study focuses on the software of the flight control systems in particular, the concept of the MIM can in principle be applied to design the complete E/E system, including hardware components, as well as other multiphysics systems.","multiphysics simulation model; electronic control system; knowledge based engineering; unmanned aerial vehicle; multidisciplinary design optimization","en","doctoral thesis","","","","","","","","2015-09-24","Aerospace Engineering","Aerospace Engineering","","","",""
"uuid:959694f4-6666-488a-8754-6c58124f4a10","http://resolver.tudelft.nl/uuid:959694f4-6666-488a-8754-6c58124f4a10","Wind energy in the built environment: Concentrator effects of buildings","Mertens, S.","van Kuik, G.A.M. (promotor); Van Bussel, G.J.W. (promotor)","2006","This thesis deals with wind energy conversion in the built environment. It gives a description of the wind resources in the built environment that can be converted into energy by a wind turbine. With a focus on maximum energy yield of the wind turbine, it especially deals with the integration of wind turbine and building in such a way that the building concentrates the wind energy for the wind turbine. Three different basic principles of such ""buildings that concentrate the wind"" or concentrators are distinguished: - wind turbines at the roof or sides of buildings, - wind turbines between two airfoil-shaped buildings, - wind turbines in ducts through buildings. The aerodynamics of those three concentrators with their possible wind turbines are investigated with a focus on integration resulting in maximum energy yield of the wind turbine. The complicated concentrator effects of buildings in the actual flow are simplified to their basic aerodynamic qualities in parallel flow. The properties of these simplified qualities in parallel flow are explored through the three well-known cornerstones of aerodynamic research: mathematical models, verification with measurements and numerical simulations of the flow. The mathematical models are derived with simplified mathematical flow descriptions. The measurements are carried out in the open jet wind tunnel of Delft University of Technology, section Wind Energy and the simulations are performed with a commercial Computational Fluid Dynamics (CFD) code, which solved the basic flow equations numerically. The advantages of both verification tools: measurement and CFD calculation are exploited by pre-selecting the tool with the best prospects for an accurate result in a desired situation. This thesis gives a broad description of the most important issues concerning the energy yield of a wind turbine in the built environment. It provides descriptions of the average/ global wind speed in the built environment, the local wind speed, the wind speed near buildings and verification of the mathematical models of the three possible concentrator principles mentioned above. Furthermore, it provides information on suitable wind turbines for use in the built environment. The pros and cons of the three concentrator principles are summarized, without mathematics, in the last chapter. This last chapter shows that the ""at roofs of buildings"" configuration and a variation on the ""in ducts through buildings"" configuration are promising. Concerning the ""at roofs of buildings"" configuration, a sphere-like building concentrates the energy in omnidirectional free stream wind the most: a factor of three to four! Such concentrators are able to overcome the problem of the low average wind speed in the built environment and enable energy yields comparable to rural areas. A variation on the ""in ducts through buildings"" configuration, two ducted ellipsoids in a cross with the duct at the cross centre, is able to concentrate the energy in omnidirectional free stream wind with a factor of approximately one and a half. The other concentrators provide a smaller energy concentration. The ""close to a building"" configuration is very efficient in using the acceleration by the building and it is a relatively cheap solution compared to the other possible concentrator principles. Still, this thesis shows that the energy yield for all concentrator configurations is limited because the wind turbines can only profit from the concentrator effects when they are relatively small compared to the building. Yet, they deliver the energy, where it is needed, the built environment, and their energy yield is felt as an energy saving in the building. Consequently, their energy yield is reflected in energy savings on the customers bill from the utility company, which is a higher reimbursement compared to rural areas. It is thus concluded that wind energy conversion in the built environment making use of the concentrator effects of buildings, is a promising renewable energy source.","wind energy; built environment","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3bc5186c-6e0e-487a-baa6-6ecffb8943d1","http://resolver.tudelft.nl/uuid:3bc5186c-6e0e-487a-baa6-6ecffb8943d1","On the detection of coherent structures in turbulent flows","Kunen, J.M.G.","Ooms, G. (promotor)","1984","","","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","Aerospace Engineering","","","",""
"uuid:7e4cfc71-57eb-4a6e-9e90-38854de21ce2","http://resolver.tudelft.nl/uuid:7e4cfc71-57eb-4a6e-9e90-38854de21ce2","Computational fluid-structure interaction: Spatial coupling, coupling shell and mesh deformation","De Boer, A.","Bijl, H. (promotor); Rixen, D.J. (promotor)","2008","","fluid structure interaction; spatial coupling; coupling shell; mesh deformation; radial basis functions","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2ab22f78-cb92-40c3-a803-1860e58daa7c","http://resolver.tudelft.nl/uuid:2ab22f78-cb92-40c3-a803-1860e58daa7c","An Asymptotic Analysis of Compressible Base Flow and the Implementation into Linear Plug Nozzles","Wisse, M.E.N.","Bakker, P.G. (promotor)","2005","The major technical challenge the development of next-generation launchers is facing today, is to achieve complete reusability in two stages to orbit or ultimately in one single stage. These Two-Stage-To-Orbit (TSTO) or Single-Stage-To-Orbit (SSTO) Reusable Launch Vehicles (RLV) may reduce payload cost by a factor of ten or more. The challenge, however, can only be met by the design of special propulsion systems equipped with so called altitude-adaptive nozzles. The most promising altitude-adaptive concept is that of the linear plug nozzle, a conventional bell nozzle turned inside out and arranged in a linear configuration. Advantages of this type of nozzle are: adaptability to varying ambient pressure; simplicity and reliability, because there are no movable parts; low engine weight, because of ease in vehicle integration and distributed thrust loads; built-in Thrust Vector Control (TVC) by throttling modular engines; and, cheap manufacturing of high-performance nozzles, because the nozzle is divided in multiple equivalent segments. The adaptability of the concept, however, ceases to exist around and beyond transonic velocities. The problem is related to the development of a lowpressure planar compressible base flow, located behind the vehicle base in the region between the separated external flow and the separated exhaust jet. Compressible base flow is a well-known fluid-dynamic phenomenon, which has been studied and analysed for many years, especially during the onset of rocketry in the late 1950s and 1960s. However, a satisfying description of the physical processes driving the base flow has as yet not been determined. Nevertheless, a proper understanding of these processes is essential for the development of a linear plug nozzle resisting external-flow effects, and is critical for the realisation of single-stage-to-orbit vehicles in general. The complexity of compressible base flow lies in the composition and interaction of multiple processes. For every separate process that can be identified in the complex flow around launch-vehicle nozzles, the local Reynolds number may be assumed high, even though corresponding length scales may be relatively small; this is a result of rather high velocities, densities and launch-vehicle sizes, and rather low viscosities. Consequently, an asymptotic approach is allowed in which the different elements of compressible base flow are treated separately. The asymptotic approach enables the analytical proof of existence and quantification of driving base-flow phenomena, such as upstream influence, isentropic compression before reattachment, and interaction of the developing shear layer with the expanded boundary layer and circulatory region. From this analysis two limiting base-flow solutions are identified. One is the well-known Chapman limit, in which the boundary-layer thickness is assumed to be negligible in comparison with the shear-layer thickness. The other is a newly-identified limit, in which the shear-layer thickness is assumed to be negligible in comparison with the boundary-layer thickness. The corresponding solution methods have been adjusted to cope with asymmetric base-flow conditions (allowing the exchange of mass and energy between the two flows), adiabatic and non-adiabatic base bleed, base heating, and the use of different species. The asymptotic solution method has been further adjusted to cope with the base flow downstream of the actual plug nozzle as well. The shear layer, developed in between the jet exhaust and this base flow, is generally redirected by reflecting expansion waves. Optimal base-bleed percentages for the plug-nozzle base flow have been determined for maximal specific impulse. Subjecting the vehicle base flow solution to a parameter-variation analysis, reveals that real exhaust gases will produce significantly higher base pressures and temperatures than cold gases (air). Clarifying the problem of base flow enables one to diminish or even avoid the negative consequences of base flow by application of a well-considered and well-shaped after body. For the case of inviscid flow the optimal conventional boat-tail shape is found to be linear. The Ventilated Trailing-Edge Cavity (VTEC), attached to the vehicle base, moreover avoids the low base pressures by relocating the reattachment point farther downstream, so that the exhaust jet still retains the ability to fulfil its altitude-adaptive tasks at supersonic flight speeds.","supersonic aerodynamics; nozzle flow; base flow; rocket propulsion; reusable launch vehicles","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b06e1485-723c-4ece-b495-100e19b56cfb","http://resolver.tudelft.nl/uuid:b06e1485-723c-4ece-b495-100e19b56cfb","Tailor-made blanks for the aircraft industry","Zad Poor, A.A.","Benedictus, R. (promotor)","2010","Tailor-Made Blanks (TMBs) are hybrid assemblies made of sheet metals with different materials and/or thicknesses that are joined together prior to forming. Alternatively, a monolithic sheet can be machined to create required thickness variations (machined TMBs). The possibility of having several thicknesses and/or materials in one single structure facilitates optimal material distribution and helps us make ground and air vehicles lighter, more cost-effective, fuel-efficient, and environment-friendly. TMBs technology has been used in the automotive industry for almost two decades mostly in the form of tailor-welded blanks, where steel or aluminum sheets are (laser) welded. The applications of the technology were, however, non-existent in the aircraft industry primarily because the fusion welding processes that are used in the automotive industry are not suitable to the precipitation-hardened high strength aluminum alloys that are used in the aircraft industry. Therefore, alternative joining (production) techniques are needed to produce TMBs in the aircraft industry. The problem is the already available know-how from the automotive industry is not applicable anymore. New research is therefore needed to generate the lacking know-how for application of the TMB concept in the aircraft industry. The objective of this dissertation is to contribute towards generating that missing knowledge.","Tailor made blanks; forming; aerospace industry; formability; springback","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Department of Aerospace Materials and Manufacturing","","","",""
"uuid:b1d69770-5303-4e42-b67b-29357ba43f41","http://resolver.tudelft.nl/uuid:b1d69770-5303-4e42-b67b-29357ba43f41","Pressure fluctuations in the turbulent boundary layer; advances in diagnostics and control","Ghaemi, S.","Scarano, F. (promotor)","2013","","","en","doctoral thesis","Delft University of Technology","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:c1fa30da-a098-4029-a678-4bdb412fdca1","http://resolver.tudelft.nl/uuid:c1fa30da-a098-4029-a678-4bdb412fdca1","Elastoplastic buckling analysis of cylindrical shells using a semi-analytical formulation","Deerenberg, E.","Arbocz, J. (promotor)","1994","","buckling; cylindrical shells","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:da89e873-850b-4e08-8b29-d348ce4c4a86","http://resolver.tudelft.nl/uuid:da89e873-850b-4e08-8b29-d348ce4c4a86","Subsurface fatigue crack growth in Glare fibre metal laminates","Randell, C.E.","Van der Zwaag, S. (promotor)","2005","The investigation of the present thesis is concerned with the fatigue crack growth behaviour of part through the thickness cracks in Glare™ fibre metal laminate (FML) subjected to combined tension and bending. An experimental program was executed which required the development of a novel fatigue specimen, the Milled Open Hole Tension Bending (MOHTB) specimen. This was developed in order to have an easily configured specimen with desired combined tension and bending stress states, and to ensure the stability of the stress levels during fatigue loading. Fatigue data was captured for all plies of the laminates. Tests were conducted on Glare 2A and Glare 3 specimens. A hybrid analytical/numerical fatigue crack growth prediction model for surface and subsurface cracks in Glare 2A was developed. Finite element modelling was required to gather fibre bridging stress distributions for the plies of the laminates. Analysis led to a stress intensity factor formulation for the crack restraining effects of the fibre bridging. This stress intensity factor, and one to account for far field loading and the specimen geometry, were superimposed into a Paris law crack growth model and was solved numerically. With this crack growth model, crack propagation curves were generated correlating to experimental conditions observed in the laboratory. The hybrid crack growth model was evaluated against the experimental data for the Glare 2A and Glare 3 specimens. The results of the comparison showed good agreement between the prediction and the experimental data.","fibre metal laminates; glare; crack propagation; fatigue; subsurface crack growth; combined tension-bending","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:cdece38a-1f13-47cc-b277-ed64fdda7cdf","http://resolver.tudelft.nl/uuid:cdece38a-1f13-47cc-b277-ed64fdda7cdf","An engineering methodology for kite design","Breukels, J.","Ockels, W.J. (promotor); Mulder, J.A. (promotor)","2011","Kites have seen substantial development in the last 10 years, going from mostly toys to high-performance sports-related equipment for e.g. kite surfing. The design process of these kites, however, is mostly a trial-and-error affair. Ten years after the sports-related kite revolution a new development is is emerging: Industrial applications for kites. Systems to propel ships and generate sustainable energy are now under development worldwide at over 40 companies and institutes. These new industrial applications will put strickter and more complex requirements on these kites. The current trial-and-error approach to the design of kites will not suffice. In this thesis a different design methodology is proposed. This methodology leans on three pillars. The first pillar is ""Knowledge"". As it turns out, there is still a lot unknown about the behavior of kites. This thesis further develops that knowledge. The seccond pillar is ""Simulation"". Nowadays, a large number of prototypes are produced and tested. So many in fact, that many designers do not even have the time to test them all. With the advance of complex industrial kites, this situation is expected to escalate. The capability of virtually testing kites will shrink the prototype phase into more managable proportions. Furthermore, it will contribute to the understanding of kites as well. This thesis proposes a number of models to simulate kites on a conventional desktop computer. These models include both rigid-body and multi-body models. The latter is capable of simulating a kite including its extreme flexibility. The third and last pillar is ""Measurement"". Controlled and reproducable measurements are essential for validation and evaluation. The thesis closes with a number of case studies which show the advantages and opportunities of this methodology.","kite; multi-body dynamics; laddermill; sustainable; design; flexible","en","doctoral thesis","Uitgeverij BOXPress, Oisterwijk","","","","","","","","Aerospace Engineering","ASSET","","","",""
"uuid:1d00c8c8-6a69-4fd9-a631-0aedfa063ac3","http://resolver.tudelft.nl/uuid:1d00c8c8-6a69-4fd9-a631-0aedfa063ac3","Computation of Rotorcraft Wake Geometry using NURBS","Van Hoydonck, W.R.M.","Van Tooren, M.J.L. (promotor)","2013","This thesis contains the results of research in the area of rotorcraft aerodynamics with a focus on method development related to the vortical wake generated by rotor blades. It is applied to a vortex tube representation of the wake (using a single NURBS surface) and a simplified filament wake model where only the tip vortices are taken into account. A complete wake model would include all vorticity (both shed and trailed) released by the blades along their entire span. Here, the wake model is reduced to the most important part: the vorticity released at the tips of the blades. In the first part of the thesis (Chapters 2–4), a vortex filament method is developed that uses Non-Uniform Rational B-Spline (NURBS) curves as the basis for the geometric description of vortex filaments. NURBS have the advantage that they are very suitable to describe curved geometry. As a consequence, fewer elements are required to get an accurate description of a curved vortex filament when compared to a discretization that uses straight line segments for which an analytical solution of the Biot-Savart law is available that gives the velocity induced by one such segment. In this thesis, an alternative method is used. The Biot-Savart law is regularized using velocity smoothing functions and the induced velocity is computed by automatic integration, using adaptive quadrature. This has the advantage that the contribution due to the local curvature at an evaluation point located on a vortex filament is taken into account automatically, which is in contrast with methods using straight line segments that require an additional correction. While validating the NURBS-based vortex methods, it was observed that the regularization of the analytical solution of the Biot-Savart law for a straight line segment that is used in the literature contains an error. A convergence analysis of the regularization shows that for evaluation points located near the centre line of a line segment beyond its endpoints, the induced velocity value does not converge towards the analytical reference, even though no asymptotes are encountered for the induced velocity as the centre line is approached. An improved correction is proposed that rectifies this error. The consequence of using the original correction in a vortex filament method are investigated using a single viscous vortex ring. The second part (Chapters 6–8) concerns the development of an explicit, multi-step wake relaxation algorithm for use in the rotorcraft trim task. The relaxation algorithm follows from a description of the trim problem, which states that vorticity released from the rotor at the same point (radius and azimuth angle) belongs to the same streamline. It is assumed that a streamline is a smooth curve that can be modelled using a cubic NURBS curve. By reversing the equation to compute the derivative along a NURBS curve at a fixed parametric point, an interpolation algorithm follows that can reconstruct a streamline given its starting point and derivative data along the curve. In Chapter 6, the method is applied to a vortex tube approximation of the rotor wake that is modelled using a single NURBS surface. The long computing times and the inability to find a trimmed solution in forward flight are the main reasons why the trim method has been adapted for a vortex filament wake model in Chapter 7. The discrete nature of a filament wake model when compared to the continuous nature of a vortex tube model, means that a small modification is necessary to make the trim method compatible with a filament wake. It is related to the position along the streamline curves where velocity is computed and where it is required to update the streamline. Harmonic interpolation is introduced as a means to improve the efficiency of the relaxation method. Viscous diffusion and the effect of stretching on the core sizes are taken into account as well. The trim method is put through its paces using an isolated rotor in hover, first out of ground effect, then in ground effect and finally, in forward flight. In Chapter 8, the filament wake trim methodology is coupled to a structural and aerodynamic model of helicopter rotor and a boundary element method to account for the influence of non-planar ground effect. The rotor is trimmed in hover above a finite ground plane that serves as a simple representation of the flight deck of a frigate.","NURBS; vortex filament; helicopter simulation; free wake; wake relaxation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:253459bb-e20b-4165-b093-81b1a8cf3a79","http://resolver.tudelft.nl/uuid:253459bb-e20b-4165-b093-81b1a8cf3a79","Weight Indexing for Multidisciplinary Design Optimization of Lifting Surfaces","Elham, A.","Van Tooren, M.J.L. (promotor)","2013","","wing design; multidisciplinary design optimization; wing weight estimation","en","doctoral thesis","","","","","","","","2013-02-08","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:69cd815f-a8bd-4602-bb37-57109a880495","http://resolver.tudelft.nl/uuid:69cd815f-a8bd-4602-bb37-57109a880495","Continuous Descent Operations using Energy Principles","De Jong, P.M.A.","Mulder, M. (promotor)","2014","During today’s aircraft descents, Air Traf?c Control (ATC) commands aircraft to descend to specific altitudes and directions to maintain separation and spacing from other aircraft. When the aircraft is instructed to maintain an intermediate descent altitude, it requires engine thrust to maintain speed, leading to increased fuel burn and noise being produced. By eliminating these level ?ight segments, fuel consumption, noise and gaseous emissions can be reduced as aircraft can perform the descent at an engine-idle thrust setting. The aircraft will then ?y a continuous descent, or Continuous Descent Operations (CDO), which at the same time raises the altitude pro?le, reducing the experienced noise levels at ground level. Today, CDO’s are operationally in use at various major airports, such as Amsterdam Airport Schiphol and London Heathrow. Due to dif?culties in predicting aircraft trajectories and time of arrival when performing CDOs, ATC needs to add additional spacing buffers to assure proper spacing between aircraft. As a result, airport capacity is reduced, limiting the use of CDOs to hours of low capacity demand. Researchers investigated various concepts in an aim to improve the predictability of CDOs to maintain airport capacity during CDOs. However, many of these concepts require additional thrust to correct for deviations. Therefore, this research developed a new CDO concept, named Time and Energy Managed Operations (TEMO), that allows an aircraft to perform accurate 4D engine-idle descents using energy principles. TEMO uses the principles of energy to correct deviations (replanning) without the need for additional thrust and simultaneously adhering to time constraints for spacing and sequencing. The concept uses an optimization algorithm to minimize thrust and speedbrake use and to calculate accurate trajectories. The algorithm uses energy management by exchanging kinetic and potential energy by controlling the elevator to correct deviations. Sustained deviations are corrected for through either strategic replanning, when deviations exceed a prede?ned boundary, or using tactical replanning, which instantaneously corrects deviations. To improve ?ight accuracy and maintain acceptable workload levels, a TEMO descent is ?own using the autopilot and auto-thrust systems. However, selection of ?aps and gear, and commanding the autopilot are examples of actions that are still performed by the pilot. The TEMO concept should be validated for different conditions to verify whether CDOs can be ?own using energy management and whether the concept can cope with various disturbances. A study should verify whether environmental impact is reduced while the various replanning methods should be compared. Various errors could be arti?cially introduced to evaluate to what extent energy management alone can correct errors and in what scenarios thrust or speedbrakes are required. Moreover, the role of the human pilot in the TEMO concept should be evaluated. The human pilot introduces additional uncertainties that affect the ?own descent. Another uncertainty during descent is wind and affects the trajectory accuracy greatly. Hence, can we improve wind estimation to enhance trajectory prediction? This thesis addresses these topics and questions. A ?rst experiment involved a fast-time batch simulation performed in MATLAB and aimed at identifying TEMO’s environmental bene?ts and ability to correct deviations and errors using strategic replanning. Deviations result from modeling errors in the Trajectory Predictor (TP) and algorithm to simplify trajectory prediction. A comparison of baseline scenarios between TEMO descents and current step-down descents showed that TEMO reduces the 65 dB and 75 dB Sound Exposure Level (SEL) contour areas by 20% and 13%, respectively. Moreover, a reduction in fuel used was achieved between 11% and 20% for the descent. When considering fuel use per ?ight time, the reduction is slightly reduced to values between 9% and 16%. Gaseous emissions were effectively reduced by approximately 33–47%. The comparison also showed that without additional errors, no replanning was required to correct deviations that result from modeling errors. Next, descents were simulated with introduced time, energy and wind estimation errors to evaluate how strategic replanning corrects such errors during descent. Without using additional thrust, a time error window of 8–16 seconds was achieved using energy management only. The actual dimensions of this time window depends on the wind estimation error. By allowing TEMO to command minimized amounts of thrust and speedbrakes, the algorithm was able to calculate a new trajectory that allowed the aircraft to arrive 30 seconds earlier and later than originally planned. In some extreme scenarios, the time deviation at the Initial Approach Fix (IAF) exceeded the 5 seconds required accuracy prescribed by the Required Time Performance (RTP). These larger time deviations primarily result from wind estimation errors that negatively affect time and energy performance. This continuous wind error resulted in multiple trajectory recalculations to correct for time and energy deviations. This experiment also compared results of descents ?own using strategic replanning with descents ?own using hybrid replanning under wind conditions. This hybrid replanning method used a 4D-speed controller to continuously (tactically) correct for time deviations and used a strategic replan before Terminal Maneuvering Area (TMA) entry to correct for energy deviations. The results showed that the 4D-controller effectively minimizes time deviations at the IAF with minimum cost to fuel use and noise contours, even when a wind estimation error is present. Hence, the tactical controller is ef?cient at correcting deviations resulting from a continuous disturbance. However, hybrid replanning showed larger energy deviations at localizer intercept which were not corrected using a replan but corrected upon glideslope intercept by the autopilot. Therefore, hybrid replanning should use stricter energy boundaries to reduce energy (and altitude) deviations when the aircraft approaches the localizer. The fast-time simulations on TEMO performance included a zero-delay pilot response model that executed pilot tasks, such as con?guration changes, perfectly. Hence, the question remained how variations in pilot response to manual actions affect TEMO performance. This question was addressed in a real-time experiment with pilots in the loop. This experiment also evaluated what information support pilots best to perform accurate TEMO descents and minimize variations in pilot response. Three Human-Machine Interface (HMI)’s were developed that provide support information during TEMO descents and differed in level of information displayed. Pilots preferred the HMI variant that included a timer to support accurate selection of ?aps and gear, and responded that workload was acceptable. This con?guration timer, however, did not signi?cantly reduce time deviations at the runway threshold but reduced the variance in delay of setting con?gurations. For comparison the pilot ?own scenarios were also ?own using a zero-delay pilot response model to investigate investigation of the effects of variations in pilot response on environmental impact and TEMO performance. A comparison of these simulations showed that human response had little effect on noise contour levels and Nitrogen Oxide emissions of a TEMO descent, while the difference in time deviation with respect to the automated runs was small. Consequently, pilots were suf?ciently informed to perform their actions. The comparison also indicated that without delays in performing pilot actions, the aircraft did not arrive exactly on time either. This resulted from simpli?cations in modeling of aircraft dynamics in the TEMO algorithm and TP and guidance errors while following the prescribed speed-pro?le. In general, the aircraft arrived early and close to the early boundary of the RTP at the runway threshold for pilot ?own scenarios. This raises the question whether an RTP of 2 seconds is achievable in real life. The guidance and planning functions should be improved to reduce this offset to be able to obtain similar time accuracies in less favorable wind conditions. The analysis of all results showed that the energy deviation at the moment of intercepting the glideslope signi?cantly in?uences the time of arrival for the automated runs, while for the human runs this effect was slightly smaller. This implies that to arrive exactly on time at the runway threshold, the energy deviation at glideslope intercept should be reduced and corrections during glideslope descent should be made possible. The results from both experiments showed that TEMO is sensitive to disturbances and errors. The batch study showed that wind estimation errors contribute greatly to time and energy deviations. For this reason, it is expected that using accurate wind estimation data in the TEMO algorithm will reduce trajectory deviations. Today, aircraft primarily rely on coarse and slowly updated wind estimates resulting in gross estimates of the prevailing wind when predicting the own trajectory. Therefore, a novel method for real-time estimation of a wind pro?le was developed, named Airborne Wind Estimation Algorithm (AWEA) that increases the temporal and spatial resolution of wind estimates. AWEA uses data transmitted by nearby aircraft to construct high resolution real-time wind pro?le estimates. The AWEA algorithm uses a Kalman ?lter to relate all received measurements to the own trajectory and reduce measurement noise. The wind estimation algorithm performance was evaluated using Mode-S derived meteorological data from Amsterdam Airport Schiphol. Using these wind observations, the AWEA algorithm showed an Root Mean Square (RMS) in the wind estimation error of 1.35 KTS along the own trajectory, which is lower than the observed RMS measurement error of 1.94 KTS. Relating the measurements to the own trajectory also proved bene?cial in reducing wind estimation errors. In another experiment, estimated wind pro?les along the own trajectory constructed by AWEA showed to improve spacing performance during approach. The TEMO experiments showed promising results as clear bene?ts to the environment have been identi?ed whilst the aircraft adheres to time constraints accurately. However, some issues require further investigation before TEMO could be used in real-life. TEMO was designed for the Airbus A320 ?ying straight-in descents and evaluated in a single aircraft environment. Future work should investigate TEMO’s use in other aircraft types, include turn dynamics, and realistic wind and turbulence conditions. AWEA should be integrated with TEMO to reduce deviations resulting from wind. Next, an experiment should investigate capacity, and spacing and separation between multiple aircraft performing TEMO descents. To improve TEMO time performance at the runway, TEMO should be able to perform replans while on the glideslope. Since energy management cannot be performed while the aircraft descents down the glideslope, deviations could be corrected using ?ap-scheduling such that engine-thrust remains idle, or a tactical component could use thrust and speedbrakes to simultaneously control time and energy. Trajectory prediction will always include modeling errors as we cannot model the world explicitly, hence, effort should be put into reducing these errors to a minimum. Since strategic replanning can be considered as an open-loop (or slow, intermittent) control system, modeling errors will always result in deviations from the planned trajectory. To improve time performance by minimizing time deviations due to modeling errors and unknown disturbances, a closed-loop system should be used. Hybrid replanning augments strategic replanning with a fast closed-loop speed controller. Hence, research should investigate how hybrid replanning can be further improved and evaluate the human factors aspects of hybrid replanning in a real-time experiment with pilots in control.","continuous descent operations; aircraft performance; approach; descent; energy principles; conservation of energy; kinetic energy; potential energy; wind estimation; trajectory prediction; optimal control theory; time and energy managed operations; human factors; human response; flight management computer; trajectory management; flight dynamics","en","doctoral thesis","","","","","","","","2014-01-13","Aerospace Engineering","Control and Simulation","","","",""
"uuid:01057a8b-6ca0-43ab-ab1a-1b3f405307b7","http://resolver.tudelft.nl/uuid:01057a8b-6ca0-43ab-ab1a-1b3f405307b7","Self-Spacing Algorithms for Continuous Descent Approaches","In 't Veld, A.C.","Mulder, M. (promotor); Van Paassen, M.M. (promotor)","2011","The thesis describes the algorithms design required to perform in-trail self-spacing during continuous descent approaches. Both distance-based and time-based spacing is treated. The CDA-procedure that is investigated is the Three-Degree Decelerating Approach (TDDA). The results of various off-line and simulator experiments as well as test flight data are presented and discussed. Both distance-based and time-based self-spacing are proven to be feasible solutions to the problem of introducing CDAs while maintaining realistic runway throughput numbers.","CDA; Continuous Descent Approach; Three-Degree Decelerating Approach; TDDA; self-spacing; in-trail spacing; noise abatement; runway throughput; runway capacity; wind estimation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Control & Simulation","","","",""
"uuid:a419574e-3583-4c8f-bd42-d3da12a58995","http://resolver.tudelft.nl/uuid:a419574e-3583-4c8f-bd42-d3da12a58995","Computational design of heat resistant steels with evolving and time-independent strengthening factors","Lu, Q.","Van der Zwaag, S. (promotor); Xu, W. (promotor)","2015","Alloy design by the traditional trial and error approach is known to be a time consuming and a highly cost procedure, especially for the design of heat resistant steel where the feedback time is intrinsically long. The significant developments in computational simulation techniques in the last decades have made a theory-guided computational alloy design possible. Such a computational approach can substantially decrease the development time costs. In this thesis a computational alloy design approach coupling thermodynamics, kinetics and a genetic algorithm has been developed to design the non-corroding ferritic, martensitic and austenitic heat resistant steels for use at a high service temperature. In the design of heat resistant steels, the evolution of the microstructure and hence properties, depends on service time and temperature and should be considered carefully. For heat resistant steels deriving part of their high strength on precipitates the coarsening of the precipitates at high temperature is considered as the most important factor and this process features highly in the design. Novel steel compositions (involving typically 9 alloying elements) and associated key heat treatment parameters are considered and optimised. The calculated optimal compositions are unlikely to be perfect and free of experimental problems but form an excellent start to initiate experimental development programs and to substantially shorten the development time of new high performance steel grades.","alloy design; heat resistant steel; computational modelling; precipitation hardening; solid solution strengthening; genetic algorithm; thermodynamic; kinetics; coarsening","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structure and Materials","","","",""
"uuid:fd466357-7890-45bd-b199-3df64df2e6d7","http://resolver.tudelft.nl/uuid:fd466357-7890-45bd-b199-3df64df2e6d7","Fluid-structure interaction simulations: Efficient higher order time integration of partitioned systems","van Zuijlen, A.H.","Bijl, H. (promotor); Bakker, P.G. (promotor)","2006","The simulation of fluid-structure interaction can be a very time-consuming task due to the large amount of time steps that need to be taken in order to obtain an accurate solution. To reduce computing times a higher order time integration algorithm is applied. Based on a mixed combination of implicit and explicit multistage Runge-Kutta schemes, the proposed algorithm integrates partitioned systems with higher order accuracy in time even without the need for sub-iterations. The method outperforms current first and second order schemes. For physically strongly coupled interactions, sub-iterations are mandatory. The computing time of sub-iterations can be greatly reduced using a two-level approach in which the sub-iterations are performed on a coarse grid. This algorithm can be used to make a coarse grid prediction before solving the partitioned system on the fine grid or to make a coarse grid correction after solving the partitioned system on the fine grid. Of these methods coarse grid prediction reduces the computational time the most.","fluid-structure interaction; partitioned integration; higher order time integration; two-level algorithm","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c6253348-532d-4159-bb4c-00cb8a1f5c2b","http://resolver.tudelft.nl/uuid:c6253348-532d-4159-bb4c-00cb8a1f5c2b","Stress analysis of fatigue cracks in mechanically fastened joints: An analytical and experimental investigation","De Rijck, J.J.M.","Vogelesang, L.B. (promotor)","2005","The two historical fuselage failures, Comet in 1954 and Aloha in 1988, illustrate that similar accidents must be avoided which requires a profound understanding of the fatigue mechanisms involved, including analytical models to predict the fatigue behavior of riveted joints of a fuselage structure. The scope of the research project covers a variety of joint types and joining techniques for both monolithic and laminated sheet materials. The fuselage structure is a rather complicated system of parts consisting of skin sheets, tear straps, stringers, frames and doublers. These parts are interconnected by mechanically fastened and bonded joints, or a combination of both. The complex fuselage structure in the present research is reduced to specimen level size for laboratory testing and theoretical analysis.\par The major topics of the thesis are: Calculations of the combined tension and bending stress distribution in joints, which implies an extension of the so-called secondary bending model (Chapter 3). Find a direct and simple relation between the formed rivet head and squeeze force. (Chapter 4). Development of stress intensity factors for fatigue cracks in joints loaded under combined tension and application to fatigue crack growth results (Chapter 5). Fractographic observations with the scanning electron microscope of crack front shapes occurring in riveted joints under combined tension and bending (Chapter 5). Analysis of the residual strength of joints with fatigue cracks (Chapter 6). Neutral line model For mechanically fastened lap splice and butt joints in a fuselage structure, a dominant load is introduced by the Ground Air Ground (GAG) pressurization cycle. The hoop load is transferred from one skin panel to the next via the fasteners in the joint. The hoop load is offset by eccentricities in the load path, which causes secondary bending. The bending stress is a non-linear function of the applied tension load. The stress system in the joint then encompasses the membrane stress, the secondary bending stress and the bearing stress associated with the fastener loads on the holes. The secondary bending is highly depending on the magnitude of the eccentricity and the flexural rigidity of the joint between the fastener rows. The theory used to derive the bending stresses is based on the advanced beam theory. A further development of the neutral line model incorporates the internal moment, which is a useful representation of the load transfer occurring in multiple row joints. The calculation of the load transfer can be made for complicated lap splice and butt joints. With the developments of the present research, the neutral line model is still a very powerful tool to use in the early stages of joint design. It gives a good picture of the stresses in a joint. Riveting Solid rivets and more advanced fasteners are still widely used in aircraft fuselage design efforts. The fasteners are characterized by various parameters associated with the fastener material and geometry, sheet material and installation process. The present investigation focuses on solid rivets installed in aluminum and Glare. The expansion of a solid rivet in a rivet hole is important with respect to the fatigue properties of joints. The expanding rivet inside a fastener hole will create a compressive residual stress around the hole and this will delay fatigue crack nucleation. It is important to know the correct squeeze force used to form the driven head of a rivet. Measurements of the formed rivet head (diameter or protruding height) can be used to obtain information about the applied squeezing force. The riveting process is a non linear deformation process characterized by large plastic strains. Simple equations based on constant volume of the rivet and the Holloman model for uniform plastic deformation, were adopted to evaluate the riveting process. Useful results were obtained about the correlation between the rivet head deformation and the applied squeezing force. Stress intensity factors As a result of combined tension and secondary bending in a lap joint, fatigue cracks at the edge of a hole start at one side of the sheet only. Initially these cracks at the edge of a hole are growing as a part through the thickness corner crack, which later become a through the thickness crack, a so called through crack. But also for a through crack, the shape of the crack front is usually curved and the crack length measured at both sides of the sheet will be different. In view of fatigue crack growth predictions it then is necessary to obtain stress intensity factors for such slant and curved crack fronts. In the present investigation this problem has been explored for a simple configuration, which is an open hole in a sheet specimen subjected to combined tension and bending. Fatigue tests were carried out on specimens of AL 2024 T3 clad sheet material with three different thicknesses (1.0, 1.6 and 2.0 mm). In each specimen a single open countersunk hole was present. The development of the crack front is these specimens could be recorded because so-called marker load cycles were applied in these tests. It then was possible to observe the crack fronts in the scanning electron microscope, which still was a rather strenuous work. Reconstruction of the crack growth could be done for the larger part of the fatigue cracks.\par K-values were obtained for a large variety of crack front shapes and crack sizes. Comparison of the new calculated K values with existing solutions showed that the new solutions capture near the surface phenomenon more accurately than the previously published data. The improvement is a result of using an increased mesh density. For through the thickness cracks growing away from the countersunk hole, the normalized stress intensity factors approach the values of the normalized stress intensity factors for cracks emanating from a straight shank hole. Thus, the effect of the countersunk hole decreases with increasing crack length. The solutions for the pin loading b values show a dominant influence of the countersunk shape in the b/t values.\par Residual strength Static failure of a joint occurs when that joint is not able to carry the applied load anymore. The type of static failure in joints depends on the loading condition and the joint configuration. The most common static failure modes in monolithic aluminum joints are fastener shear failure, plate tension failure, bearing failure and plate shear failure. In Glare joints another failure mechanism, fastener pull-through, is often observed. This failure mechanism is related to the lower stiffness of Glare in thickness direction, leading to increased tilting of the fasteners and hence increased tensile stresses in the fastener. \par In the present thesis, a method is proposed to calculate the residual strength of joints of monolithic and fiber metal laminates. The method uses the remaining net section. For the fiber metal laminates the net section includes the remaining intact metal layers in combination with the intact fibers. The method starts with the blunt notch strength of the un cracked joint and the metal volume fraction for the fiber-metal laminates. The Norris failure criterion and the metal volume fraction are used to calculate the blunt notch strength for any possible Glare lay up. Secondary bending has a significant influence on the ultimate strength of both Glare and aluminum. The ultimate tensile strength reduces with increasing bending. Taking this into account, an empirically found reduction of 10% of the blunt notch values results in a more accurate representation of the stress system. Difficulties arise if significant plastic deformation occurs at the most critical fastener row, and further research using a finite element model is recommended.","fiber metal laminate; neutral line model; stress; load transfer; rivet; fatigue; fastener; riveted joint; fractography; finite element analysis; crack growth predictions; residual strength","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ca4b93ac-6a39-4c89-8699-e0a351e7fe2f","http://resolver.tudelft.nl/uuid:ca4b93ac-6a39-4c89-8699-e0a351e7fe2f","An Optimal Control Approach to Helicopter Noise and Emissions Abatement Terminal Procedures","Hartjes, S.","Curran, R. (promotor)","2015","Civil aviation plays an irreplaceable role in the current global civilization. Even though the 2008 economic crisis has limited growth in the western world, it can only be expected that due to continuing development in the Far East, South America and Africa this role will increase further over the years to come. Also in the field of helicopter operations continuous growth is predicted, mainly attributed to the growth of the private and corporate transport sectors. To reduce and control the negative impacts of aviation – mainly noise nuisance and pollutant emissions – both in Europe and the United States major research efforts have been initiated with the main objective to provide step changes in the development of environmentally friendly or green aircraft. Although the larger part of the research effort has been focused on the development of new air vehicles, also the development of green operations is being researched, especially with a focus on noise abatement. Researchers have mainly focused on the development of noise abatement departure and arrival procedures for fixed-wing aircraft in an effort to reduce the noise impact in near-airport communities, with promising results. With the current fleet of helicopters the total noise nuisance caused by helicopter operations is significantly smaller than that of fixed-wing aircraft. However, due to their specific types of operations – often flying in close proximity to densely populated areas – individual operations can lead to unacceptable levels of nuisance, which require a specific approach in the development of noise abatement procedures. Therefore, in this research the European Clean Helicopter Optimization (ECHO) software suite has been developed which provides an efficient and sufficiently accurate means to numerically optimize site-specific helicopter approach trajectories, focusing specifically (but not exclusively) on noise mitigation in the surrounding communities. To provide a step change in helicopter optimization frameworks, the ECHO suite has been developed with a strong emphasis on computational efficiency. For this purpose, an advanced optimization methodology based on optimal control theory has been selected. In this method, the infinite-dimensional optimal control problem is discretized, and the time, state and control variables at the discretization point are treated as the variables of a large-scale Non-Linear Programming (NLP) problem. The method – more specifically a direct solution method based on pseudospectral collocation using Radau quadrature – has been chosen as it offers the best trade-off between accuracy and computational efficiency for three main reasons. Firstly, the use of a direct solution method to solve the optimal control problem requires significantly less complex problem setups, and as such results in a more flexible and versatile optimization suite. In addition, the selected methodology allows for a relatively easy imposition of constraints on both the state and control variables, and the use of collocation based on Gaussian quadrature reduces the overall problem size for a given level of accuracy. Finally, the specific use of Radau quadrature has been shown to provide good convergence behavior, specifically in open ended trajectory optimization problems such as considered in this study. To model the free motion of a helicopter an eight Degrees-of-Freedom (DoF) helicopter flight dynamics model with quasi-steady inflow angles for both the main and tail rotor has been integrated in ECHO. The model ensures that the motion of the helicopter is simulated sufficiently accurate, and ensures that the required input parameters to determine the helicopter source noise are directly available. The model has been adapted to simulate operations in non-standard atmospheric conditions including stationary wind fields. In addition, a fuel and gaseous emissions model has been integrated in the flight dynamics model to determine the total fuel burn and total emission of nitrogen oxides based on the required engine power. This allows for the optimization of trajectories with respect to fuel and NOx emissions. Although the model is a generic flight dynamics model, to test the capabilities of the suite a set of parameters representing a Messerschmitt-Bölkow-Blohm (MBB) Bo-105 has been used. These include a set of generic limits and constraints related to passenger comfort and the helicopter's flight envelope. To allow assessment of and hence optimization with respect to the noise impact on the ground, the ECHO suite contains a helicopter noise model consisting of three main components. The first component determines the source noise levels emitted by the helicopter. To model this, a database of source noise levels for different frequencies and different flight conditions is available, projected on a hemisphere centered around the helicopter's main rotor hub. The database has been derived aeroacoustically based on the disc-tilt angles and the advance ratio following from the flight dynamics model. Source noise levels corresponding to the actual flight conditions encountered in the optimization process are found through interpolation between the hemispheres. The second step in determining the noise exposure on the ground is the assessment of the propagation loss between source and receiver. An efficient model to determine the propagation loss was developed specifically for integration in the ECHO suite to comply with the continuity requirements following from the selected optimization methodology and to maintain relatively short execution times. The propagation model uses a geometrical approach to ray-tracing to determine the path of sound rays traveling from the source to the receiver. This approach allows for a significantly lower number of integration steps – and hence shorter runtimes – with sufficient accuracy for the atmospheric conditions considered in this research. The propagation model integrated in ECHO accounts for spreading loss, ground effect and atmospheric absorption, and includes a model to approximate the noise penetrating the shadow zone to ensure continuity in all observer locations and hence in the objective function. The final component of the helicopter noise model determines the total noise impact on the ground in order to allow for the optimization of noise abatement trajectories. A number of generic and site-specific noise impact assessment criteria is available in ECHO to quantify the total noise impact in the area surrounding the trajectory. To exemplify the capabilities of the ECHO suite a number of case studies with increasing complexity and different optimization criteria is presented. The first scenario, a relatively simple two-dimensional approach, shows that in order to minimize the noise Sound Exposure Level (SEL) footprint areas in general flight at low altitude and high airspeeds are preferred. Apart from the relatively low source noise levels at high airspeeds, also the total exposure time is reduced, reducing the SEL values. Furthermore, the presence of shadow zones and the dissipation of sound energy by the ground surface results in lower noise levels astride the helicopter's trajectory when flying at low altitudes. Consequently, SEL contours remain relatively narrow, and hence the generic noise footprint becomes smaller. In the second case study a more complex three-dimensional trajectory is optimized in a densely populated area. In addition, for this scenario the site-specific awakenings criterion was used in the objective function, and different atmospheric and ground surface conditions were assessed. Similar to the conclusions drawn from the first scenario, again low altitude flight at high airspeeds reduce the SEL values on which the awakenings criterion is partly dependent. In addition, the use of a site-specific noise criterion and a three-dimensional flight path allows the helicopter not only to reduce the noise levels astride or below the trajectory, but also to avoid densely populated areas. In the cases where wind from different directions and different strengths were considered, it was found that even though the effect of wind on the total number of awakenings was significant, the effect on the relative improvements to be gained through optimization was small when compared to optimization in standard atmospheric conditions. The effect on the total number of awakenings can be attributed mainly to changes in ground speed on the one hand, and the positioning of the helicopter such that significant parts of the population are inside the shadow zone on the other. In cold atmospheric conditions the atmospheric absorption loss increases, resulting in a generally higher flight profile in order to increase the slant range between source and receiver. The opposite is true in case softer ground surfaces (such as e.g. snow) are modeled. The soft ground surface leads to an increased dissipation of sound energy on the ground, and hence to a larger lateral attenuation leading to a stronger preference for low altitude flight. Finally, the third case study was set up to assess the effect of different site-specific noise optimization criteria on a complex three-dimensional arrival trajectory. The third scenario further supported the findings with respect to noise abatement found in the first two case studies, and additionally showed that the different site-specific criteria do not lead to significant changes in the helicopter trajectory when minimizing the total noise impact. In addition to the main conclusions from the case studies regarding noise abatement, with respect to the efficiency of the ECHO suite – one of the main objectives of the software, the case studies have shown that the suite is capable of optimizing helicopter trajectories with a complex set of constraints imposed with relatively short runtimes, depending highly on the overall problem size and problem complexity. From the development and the analysis of the capabilities of the ECHO suite it can be concluded that the objective of providing an efficient means to optimize helicopter trajectories with respect to different environmental and economic criteria has been met. Although the objectives with respect to total problem runtimes were not met in all cases, further development of the suite has seen a further step change in the overall efficiency, showing the potential to indeed meet the challenging requirements. Although the case studies have shown the potential of the suite, and ECHO meets the accuracy requirements to indeed prove to be a step change with respect to state of the art research, further improvements were identified. Especially the source noise model requires an expansion of the database to allow modeling of flight conditions other than steady forward level or descending flight at different airspeeds. This, in combination with the modeling of noise other than the main rotor would allow for a more accurate assessment of the noise impact for a wider range of flight conditions. Furthermore, the capabilities of the ECHO suite should be assessed for different helicopter classes, and in more realistic case studies, better accounting for all operational constraints encountered in real-world operations. Finally, although the ECHO suite has been developed specifically for the optimization of conventional helicopter trajectories, the flight dynamics, noise modeling and model integration in general could easily be adapted for the optimization of novel helicopter concepts or fixed-wing aircraft trajectories, further extending the research scope of the suite.","optimal control; helicopters; noise abatement","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Air Transport & Operations","","","",""
"uuid:0b3eaf1a-c0c6-40ea-95ac-4bab17bd1180","http://resolver.tudelft.nl/uuid:0b3eaf1a-c0c6-40ea-95ac-4bab17bd1180","A unified theory for linearized shock-on-shock interaction problems","Arora, N.L.","Steketee, J.A. (promotor)","1969","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:65e09cf9-573f-4839-a671-8edcba31eda4","http://resolver.tudelft.nl/uuid:65e09cf9-573f-4839-a671-8edcba31eda4","All for one: Factors for alignment of inter-dependent business processes at KLM and Schiphol","Perié, R.P.","Santema, S.C. (promotor)","2008","As airline and hub competition becomes fiercer, airline-airport co-operation becomes a necessary option for both main carrier airlines and hub airports to face this competition together. The inter-dependency between airlines and airports in producing air-transport services is tight, i.e. their destinies are inter-twined. Their existence as viable economic entities depends upon market performance of each other. This leads to the assumption that the relation of airlines' airports serves as an example case for dyadic alignment. Although research has been carried out regarding many forms of co-operation, little is known about specifically alignment at the business process level. By alignment of their inter-dependent dyadic business processes competitive advantage can be obtained; both KLM and AAS have acknowledged this. The aim of this research is to determine Factors for Alignment for specific inter-dependent business processes at KLM and AAS. For research purposes the research question is formulated as follows: Which are the factors for alignment of dyadic business processes at KLM and AAS? Answers to this research question are to increase the understanding of the effect of different factors upon alignment. This research has a theoretical as well as a practical value. It develops a theoretical Delft Factors for Alignment (DFA) model. This enables subsequent development of analysis tools that quantitatively and qualitatively measure the performance of Factors for Alignment. For practical purposes, it identifies issues and maps differences and similarities present between KLM and AAS within their specific dyadic business processes. These dyadic processes are Environmental Capacity, Network Planning, Infrastructure Planning and Aircraft Stand Allocation. This research is based upon the assumption that alignment of the dyadic business processes of KLM and AAS is achieved by addressing the issues affecting alignment regarding various subjects within each business process, as indicated by employees of these firms. By making use of interviews and questionnaires within both firms it is found that the issues present within four dyadic business processes of these firms, at three different levels of decision making, can be modeled by the developed DFA model. The model identifies the most potential of Factors for Alignment of their dyadic business processes. It is proven that the DFA model is a diagnostic tool in finding the Factors for Alignment of dyadic business processes of KLM and AAS by creating a structured ordering of the issues by interviews and questionnaires. The research question, as formulated above, is answered by primary and secondary Factors for Alignment per business process. This also implies that the DFA model is effective for analysis of dyadic business processes. The research methodology has proven to be viable. This would encourage application for research of other dyadic business processes at KLM and AAS, which could also strengthen their competitive advantage.","factors; alignment; business processes; dyads; inter-dependency; airline-airport relationship","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f95da308-e7ef-47de-abf2-aedbfa30cf63","http://resolver.tudelft.nl/uuid:f95da308-e7ef-47de-abf2-aedbfa30cf63","Generic Analysis Methods for Gas Turbine Engine Performance: The development of the gas turbine simulation program GSP","Visser, W.P.J.","Van Buijtenen, J.P. (promotor)","2015","Numerical modelling and simulation have played a critical role in the research and development towards today’s powerful and efficient gas turbine engines for both aviation and power generation. The simultaneous progress in modelling methods, numerical methods, software development tools and methods, and computer platform technology has provided the gas turbine community with ever more accurate design, performance prediction and analysis tools. An important element is the development towards generic tools, in order to avoid duplication of model elements for different engine types. This thesis focuses on the development of generic gas turbine system performance simulation methods. This includes the research required to find the optimal mathematical representation of the aero-thermodynamic processes in the gas turbine components in terms of fidelity, accuracy and computing power limitations. The results have been applied in the development of the Gas turbine Simulation Program GSP. GSP is a modelling tool for simulation and analysis of gas turbine system performance. This involves 0-D (i.e. zero-dimensional or parametric) component sub-models that calculate averaged values for parameters such as pressures and temperatures at the gas path stations between the components. The component sub-models are configured (‘stacked’) corresponding to the gas turbine configuration. Component performance is determined by both aero-thermodynamic equations and user specified characteristics, such as turbomachinery performance maps. If higher fidelity is required at a specific location in the system model, 1-D component models can be added to predict the change in gas state or other parameters as a function of a spatial (usually in the direction of a streamline) parameter. Non-linear differential equations (NDEs) are used to represent the conservation laws and other relations among the components. The sets of NDEs are automatically configured depending on the specific gas turbine configuration and type of simulation. Simulation types include design point (DP), steady-state off-design (OD) and transient simulations. The research and development challenge lies in the development of generic, accurate and user friendly system modelling methods with sufficient flexibility to represent any type of gas turbine configuration. The accuracy and fidelity is enhanced by the development of modelling methods capturing secondary effects on component and system performance in 0-D or 1-D sub-models. Object oriented software design methods have been used to accomplish the flexibility objectives, also resulting in a high degree of code maintainability. This allows easy adaptation and extension of functionalities to meet new requirements that are emerging since the start of the development of GSP in its current form (1997). The object oriented architecture and how it relates to the system and component modelling and the ensuing solving of the NDEs, is described in the thesis. An important element has been the development of the gas model with chemical equilibrium and gas composition calculations throughout the cycle. Fuel composition can be specified in detail for accurate prediction of effects of alternative fuels and also detailed emission prediction methods are added. The gas model uses a unique and efficient method to iterate towards chemical equilibrium . The object oriented architecture enabled the embedding of a generic adaptive modelling (AM) functionality in the GSP numerical process and NDEs, providing best AM calculation speed and stability. With AM, model characteristics are adapted for matching specified (often measured) output parameter values for engine test analysis, diagnostics and condition monitoring purposes. The AM functionality can be directly applied to any GSP engine model. The recent trend towards the development of micro turbines (with very high surface-to-volume ratios in the gas path) requires accurate representation of thermal (heat transfer) effects on performance. For this purpose, GSP has been extended with an object oriented thermal network modelling capability. Also, a 1-D thermal model for representing the significant heat soakage effects on micro turbine recuperator transient performance has been developed. For real-time transient simulation, the Turbine Engine Real-Time Simulator (TERTS) modelling tool has been derived from GSP. In TERTS, the methods from GSP are used with fidelity reduced to some extent in order to meet the real-time execution requirements. GSP has been applied to a wide variety of gas turbine performance analysis problems. The adaptive modelling (AM) based gas path analysis functionality has been applied in several gas turbine maintenance environments. Isolation of deteriorated and faulty turbofan engine components was successfully demonstrated using both test rig data and on-wing data measured on-line during flight. For a conceptual design of a 3kW recuperated micro turbine for CHP applications, design point cycle parameters were optimized based on careful component efficiency and loss estimates. Worst and best case scenarios were analysed with GSP determining sensitivity to deviations from the estimates. The predictions have proven very accurate after a test program showing 12% (electric power) efficiency on the first prototype. For increasing the efficiency towards 20%, GSP was used to predict the impact of several design improvements on system efficiency. GSP was used to study the effects on performance and losses of scaling micro turbines in the range of 3 to 36 kW. At small scales, turbomachinery losses become relatively large due to the smaller Reynolds number (larger viscous losses) and other effects. The scale effects have been analysed and modelled for the turbine and compressor and GSP has been used to predict the effects on system efficiency. Other applications include prediction of cumulative exhaust gas emissions of the different phases of commercial aircraft flights, simulation of thermal load profiles for hot section lifing studies, alternative fuel effect studies, performance prediction of vertical take-off propulsion systems and reverse engineering studies. The object oriented design of GSP has proven its value and has provided the building blocks for an ever increasing number of component models, adaptations and extensions. The flexibility of GSP is demonstrated with the modelling of novel cycles, including a parallel twin spool micro turbine with a single shared combustor, a rotating combustor micro turbine concept, a modern heavy duty gas turbine with a second (reheat) combustor and a multi-fuel hybrid turbofan engine, also with a reheat combustor. Several new capabilities have been developed following new requirements from the user community, using the original object oriented framework and component model classes. In the future, new technologies may replace today’s simulation tools. Maybe even the concept of modelling and simulation as we know it today will entirely change. However, as long as gas turbines and related systems will be developed and operated, there will be a need to understand their behaviour. The fundamental physics behind this will not change nor will the equations describing the processes. In that sense, GSP can be seen as a phase in the development of gas turbine modelling and simulation technology. An interesting question would be, how long will GSP remain before it is left behind for new ways. A lot will depend on the ability of GSP and its developers to adapt to future needs and also future opportunities emerging from new modelling, simulation, and computer and software technologies. So far however, GSP has proven a remarkable track record and will be around for quite a while, serving many scientists and engineers interested in gas turbine system performance analysis and simulation.","gas turbine; simulation; performance modelling; object orientation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","AWEP","","","",""
"uuid:fcee7dba-4afd-43bc-84b7-778be05bba99","http://resolver.tudelft.nl/uuid:fcee7dba-4afd-43bc-84b7-778be05bba99","Measuring, modeling and mitigating biodynamic feedthrough","Venrooij, J.","Mulder, M. (promotor); Bülthoff, H.H. (promotor); Abbink, D.A. (promotor)","2014","Vehicle accelerations affect the human body in various ways. In some cases, accelerations cause involuntary motions of limbs like arms and hands. If someone is engaged in a manual control task at the same time, these involuntary limb motions can lead to involuntary control forces and control inputs. This phenomenon is called biodynamic feedthrough (BDFT). The control of many different vehicles is known to be vulnerable to BDFT effects, such as that of helicopters, aircraft, electric wheelchairs and hydraulic excavators. The fact that BDFT reduces comfort, control performance and safety in a wide variety of vehicles and under many different circumstances has motivated numerous efforts into measuring, modeling and mitigating these effects. It is known that BDFT dynamics depend on vehicle dynamics and control device dynamics, but also on factors such as seating dynamics, disturbance direction, disturbance frequency and the presence of seat belts and arm rests. The most complex and influential factor in BDFT is the human body. It is through the human body dynamics that the vehicle accelerations are transferred into involuntary limb motions and, consequently, into involuntary control inputs. Human body dynamics vary between persons with different body sizes and weights, but also within one person over time. The goal of the research was to increase the understanding of BDFT to allow for effective and efficient mitigation of the BDFT problem. The work dealt with several aspects of biodynamic feedthrough, but focused on the influence of the variable neuromuscular dynamics on BDFT dynamics. The approach of the research consisted of three parts: first, a method was developed to accurately measure BDFT. Then, several BDFT models were developed that describe the BDFT phenomenon based on various different principles. Finally, using the insights from the previous steps, a novel approach to BDFT mitigation was proposed.","biodynamic feedthrough; neuromuscular admittance; accelerations; manual control; neuromuscular system","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:3e141764-5f47-419d-91cc-2493556e6ba5","http://resolver.tudelft.nl/uuid:3e141764-5f47-419d-91cc-2493556e6ba5","Design and Analysis Methodologies for Inflated Beams","Veldman, S.L.","Beukers, A. (promotor)","2005","The central theme of the thesis is bending behaviour of inflated beams. Three different types of beams have been analysed for the bending load case: a straight cylindrical beam made of anisotropic foil material, a conical beam made of an isotropic foil material, and a carbon fibre braided beam. The last two types have been optimised for minimum deflection at a constant weight. The interaction between a series of beams placed parallel to each other has been researched as well. For the research use is made of theoretical, experimental and finite element analysis methods. Because of the non-linear behaviour use has been made of the finite element package ABAQUS.","inflated beams; braids; cones","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1f6cd5e6-08ad-4f0f-ba40-ea51ee0f4c16","http://resolver.tudelft.nl/uuid:1f6cd5e6-08ad-4f0f-ba40-ea51ee0f4c16","Advanced Spatial Discretisation Strategies for Localised Failure - Mesh Adaptivity and Meshless Methods","Askes, H.","de Borst, R. (promotor)","2000","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a05bbbd4-fa38-473d-b984-bfa5ade6c00f","http://resolver.tudelft.nl/uuid:a05bbbd4-fa38-473d-b984-bfa5ade6c00f","Tailoring the mechanical properties of titanium alloys via plasticity induced transformations","Neelakantan, S.","Van der Zwaag, S. (promotor)","2010","Titanium alloys possess good corrosion properties, high temperature stability and high strength-to-weight ratio. However, they fall short in providing the optimum strength-ductility relation in the most demanding structural applications, including the aerospace sector. Inspired by the possibility of enhancing the strength-ductility relation in steels through the TRIP effect, the thesis elucidates at: i) identifying and quantifying the key factors that effectively control and/or promote such effect (termed here as Plasticity induced Transformation in Titanium alloys (PiTTi)), and exploring the plausible property improvements it may lead in metastable beta titanium alloys, through experimentation; ii) theoretically optimizing the key factor, Ms temperature, by proposing a thermodynamic based model for prediction of martensite formation (i.e., Ms temperature) in both binary and multi-component beta titanium alloys with effective validation; and iii) proposing, by controlling the mentioned key factors that effectively promote PiTTi effect, a novel theoretical alloy design methodology that lead to achieving new grades of titanium alloys for potentially improved properties.","titanium alloys,; Ms temperature model,; alloy design,; thermodynamics,; martensitic transformation,; metastable beta alloys,; mechanical properties","en","doctoral thesis","Ipskamp Drukkers","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:c639ce70-4ea9-4c9b-8594-bb4b51e42c73","http://resolver.tudelft.nl/uuid:c639ce70-4ea9-4c9b-8594-bb4b51e42c73","Analyses of Aircraft Responses to Atmospheric Turbulence","Van Staveren, W.H.J.J.","Mulder, J.A. (promotor)","2003","The response of aircraft to stochastic atmospheric turbulence plays an important role in aircraft-design (load calculations), Flight Control System (FCS) design and flight-simulation (handling qualities research and pilot training). In order to simulate these aircraft responses, an accurate mathematical model is required. Two classical models will be discussed in this thesis, that is the Delft University of Technology (DUT) model and the Four Point Aircraft (FPA) model. Although they are well estabilished, their fidelity remains obscure. The cause lies in one of the requirements for system identification; it has always been necessary to relate inputs to outputs to determine, or identify, system dynamic characteristics. From experiments, using both the measured input and the measured output, a mathematical model of any system can be obtained. When considering an input-output system such as an aircraft subjected to stochastic atmospheric turbulence, a major problem emerges. During flighttests, no practical difficulty arises measuring the aircraft motion (the output), such as the angle-of-attack, the pitch-angle, the roll-angle, etc.. However, a huge problem arises when the input to the aircraft-system is considered; this input is stochastic atmospheric turbulence in this thesis. Currently, during flighttests it still remains extremely difficult to identify the entire flowfield around an aircraft geometry subjected to a turbulent field of flow; an infinite amount of sensors would be required to identify the atmospheric turbulence velocity component's distribution (the input) over the vehicle geometry. In an attempt to shed some more light on solving the problem of the response of aircraft to atmospheric turbulence, the subject of this thesis, it depends on the formulation of two distinct models: one of the atmospheric turbulence itself (the atmospheric turbulence model), and the other of the aircraft response to it (the mathematical aircraft model). As concerns atmospheric turbulence, stochastic, stationary, homogeneous, isotropic atmospheric turbulence is considered in this thesis as input to the aircraft model. Models of atmospheric turbulence are well established. As for mathematical aircraft models, many of them have been proposed before. However, verifying these models has always been extremely difficult due to the identification problem indicated above. As part of the mathematical aircraft model, (parametric) aerodynamic models often make use of (quasi-) steady aerodynamic results, that is all steady aerodynamic parameters are estimated using either results obtained from windtunnel experiments, handbook methods, Computational Aerodynamics (CA) which comprises Linearized Potential Flow (LPF) methods, or Computational Fluid Dynamics (CFD) which comprises Full-Potential, Euler and Navier-Stokes methods. In this thesis the simplest form of fluid-flow modeling is used to calculate the time-dependent aerodynamic forces and moments acting on a vehicle: that is unsteady Linearized Potential Flow (LPF). The fluid-flow model will result in a so called ""unsteady panel-method"" which will be used as a virtual windtunnel (or virtual flighttest facility) for the example discretized aircraft geometry, also referred to as the ""aircraft grid"". The application of the method ultimately results in the vehicle's steady and unsteady stability derivatives using harmonic analysis. Similarly, both the steady and unsteady gust derivatives for isolated atmospheric turbulence fields will be calculated. The gust fields will be limited to one-dimensional (1D) longitudinal, lateral and vertical gust fields, as well as two-dimensional (2D) longitudinal and vertical gust fields. The harmonic analysis results in frequency-dependent stability- and gust derivatives which will later be used to obtain an aerodynamic model in terms of constant stability- and gust derivatives. This newly introduced model, the Parametric Computational Aerodynamics (PCA) model, will be compared to the two classical models mentioned earlier, that is the Delft University of Technology (DUT) model and the Four-Point-Aircraft (FPA) model. These three parametric aircraft models are used to calculate both the time- and frequency-domain aerodynamic model and aircraft motion responses to the atmospheric turbulence fields indicated earlier. Also, using the unsteady panel-method the aircraft grid will be flown through spatial-domain 2D stochastic gust fields, resulting in Linearized Potential Flow solutions. Results will be compared to the ones obtained for the parametric models, i.e. the PCA-, DUT- and FPA-model. From the results presented, it is concluded that the introduced PCA-model is the most accurate for all considered gust fields. Compared to the Linearized Potential Flow solution (which is assumed to be the benchmark, or the model that approximates reality closest) the new parametric model shows increased accuracy over the classical parametric models (the DUT- and FPA-model), especially for the aircraft responses to 2D gust fields. Furthermore, it shows more accuracy in the aircraft responses to 1D longitudinal gust fields. Although results will be presented for a Cessna Ce550 Citation II aircraft only, the theory and methods are applicable to a wide variety of fixed-wing aircraft, that is from the smallest UAV to the largest aircraft (such as the Boeing B747 and the Airbus A380).","flight dynamics; atmospheric turbulence; computational aerodynamics; potential flow; panel method; loads; system identification; unsteady aerodynamics","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f576163e-3d28-4b76-b50e-2431622c1da5","http://resolver.tudelft.nl/uuid:f576163e-3d28-4b76-b50e-2431622c1da5","Impact analysis of composite structures","Talagani, M.R.","Gurdal, Z. (promotor); Kassapohlou, C. (promotor)","2014","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:9a6d5315-dcfd-4307-a89d-2215bb60369e","http://resolver.tudelft.nl/uuid:9a6d5315-dcfd-4307-a89d-2215bb60369e","Analysis of dynamic aircraft landing loads, and a proposal for rational design landing load requirements","IJff, J.","Taub, J. (promotor); Van der Neut, A. (promotor)","1972","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4d4fadce-d064-47b4-84fe-3fb15d76b696","http://resolver.tudelft.nl/uuid:4d4fadce-d064-47b4-84fe-3fb15d76b696","Azomethine-based Donor Materials for Organic Solar Cells","Petrus, M.L.","Dingemans, T.J. (promotor)","2014","Solution processable organic photovoltaics (OPVs) are attracting much attention because of their anticipated advantages such as low cost, flexibility, lightweight, and the potential to be produced on a large scale. The photoactive layer of OPVs consists of a blend of an electron donating and an electron accepting material. Over the last 20 years, a plethora of (record breaking) electron?donating materials have been reported, which are mostly synthesized via transition metal mediated aryl?aryl coupling reactions. These chemistries, however, make use of expensive metal catalysts, inert reaction conditions and require time?consuming product purification steps. In order to offer a more economic route towards OPVs we have explored novel conjugated azomethine?based (–N=CH–) donor materials and the initial results are presented in this thesis. The azomethine bond is isoelectronic to the vinyl bond (–CH=CH–) and displays similar optoelectronic and thermal properties. In addition, azomethines offer significant advantages over vinylenes as they can be prepared using Schiff base condensation chemistry under near ambient reaction conditions. Expensive catalysts are not required and water is the only by?product. The main objective of this research is to explore the use of azomethine?based donor materials in bulk heterojunction solar cells. The design and synthesis of azomethine?based polymers, (hyper?branched) oligomers, small?molecules (both linear and star?shaped) and their performance in photovoltaic devices will be presented in this thesis.","Azomethines; organic photovoltaics; solar cells; polymers; small-molecules","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:efb5e4ac-61c4-44cc-963e-373551dbc35c","http://resolver.tudelft.nl/uuid:efb5e4ac-61c4-44cc-963e-373551dbc35c","Novel H2 manufacturing routes. Simulation and thermodynamic analysis of membrane based processes","Ji, P.","De Swaan Arons, J. (promotor)","2004","Nowadays hydrogen is gaining more and more attention mainly because it is generally regarded as an important future fuel. Although H2 can be produced from a wide variety of resources using a range of different technologies, natural gas is generally preferred and will remain in the near future the major feedstock for the manufacture of H2. Catalytic partial oxidation (CPO) is seen as a key technology for the conversion of methane in H2. The H2 produced by the conventional CPO process is mixed with other gases. For this fuel gas mixture rich in H2, the fuel cell does not convert at least 15% of the H2 that has been fed into it. Membrane reactors can be used to produce pure H2, and then the utilization of the hydrogen produced can be enhanced, in the mean time, the process can be simplified. The membrane reactors which have been studied, include the O2-membrane CPO reactor, the H2-membrane CPO reactor, the two-membrane CPO reactor (a CPO reactor with O2 and H2 permeable membrane), and the H2-membrane water-gas-shift (WGS) reactor. Three integrated processes around these membrane reactors are proposed and compared with the conventional CPO process based on the results of a thermodynamic analysis. For performing a thermodynamic analysis, a wide range of data is required. To fulfil the data requirement, the simulation has to be accomplished, especially for the CPO and WGS reactors, without and with membranes. The simulation work is based on the kinetics of the reaction and membrane permeation mechanisms. With the simulation models the profiles of temperature and molar fraction of different species along the reactor' s axial coordinate have been simulated. The validity of the simulation work has been confirmed by the comparison of simulation results with the experimental data. Because of the key role played by the CPO reactors in each corresponding integrated processes, the production rates of useful products by different CPO reactors have been simulated and compared. The effect of each adjustable inlet condition on the output of the CPO reactors has been shown and discussed. On the basis of the simulation work and the knowledge of the characteristics of the conventional CPO reactor and the membrane CPO reactors, the thermodynamic analysis of the integrated conventional and membrane CPO methane conversion processes has been carried out. The results have been used to design and optimise the processes around each CPO reactor. The most efficient process has been identified. The resulting exergy balance for each process has been used to determine where and to what extent the exergy, that part of the energy contained that is available for useful work (such as electricity from a fuel cell), is dissipated. Also on the basis of the simulation work, the thermodynamic analysis of an integrated H2 production process with a fixed-geometry H2-membrane reactor has been described. The effect of different inlet conditions on the overall exergy efficiency of the process has been shown and discussed. The simulation and thermodynamic analysis have provided a quantitative tool to get insight into and to understand the various hydrogen production processes.","thermodynamic analysis; fuel cell; membrane reactor; membrane; catalytic partial oxidation; simulation","en","doctoral thesis","Printpartners IPSKAMP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2af44705-79a3-4e4d-9e2f-10b76db6605c","http://resolver.tudelft.nl/uuid:2af44705-79a3-4e4d-9e2f-10b76db6605c","On the analysis of riveted repair patch","Mahardika, A.","Rothwell, A. (promotor)","1999","","complex function theory; displacement compatibility method; load transfer distribution; by-pass load (stress); secondary bending; ""two-step"" method; rivet squeezing; stress severity factor","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:fcf6a51a-1abd-4751-8ae5-338dbb23bce2","http://resolver.tudelft.nl/uuid:fcf6a51a-1abd-4751-8ae5-338dbb23bce2","Delamination and debonding failure of laminated composite T-joints","Cui, H.","Beukers, A. (promotor); Koussios, S. (promotor)","2014","Composites are increasingly being used in aerospace, automotive and other industries. The T-joint (also named stringer stiffened skin) is a typical connection, broadly used in thin-walled structures, such as the wing and fuselage of aircraft. This thesis presents the analysis of the delamination and debonding failure of laminated composite T-joints, in support of the design and manufacture of integrated composite structures. Major attention has been paid to expand current knowledge on the failure response of the subcomponents of the T-joints: the through thickness reinforcements and adhesive layers were investigated both numerically and experimentally. Novel experimental methods and computational models have been developed to facilitate the characterization of these subcomponents and the in-depth understanding of the failure mechanisms of these subcomponents. The cohesive zone model has been used widely for modeling various fracture problems of the investigated materials. Novel cohesive laws were developed to represent the complex constitutive responses of these materials, and different mesh distribution strategies were employed as well. Pull-off and bending tests of T-joints were carried out where the failure process and loading capacity were evaluated. On the basis of the knowledge and analysis methods accumulated from the subcomponent studies, the delamination and debonding failure of T-joints has been numerically modeled; comparisons with experimental results have validated the accuracy and reliability of these numerical models. It is believed that this thesis has contributed to better understanding of the delamination and debonding failure of composite T-joints; the knowledge, methods and philosophy outlined here may also be applied to other composite/adhesively bonded structures as well.","composites; delamination; debond; cohesive zone model","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:e0c5e170-fd84-46a8-a401-92eedcb32c39","http://resolver.tudelft.nl/uuid:e0c5e170-fd84-46a8-a401-92eedcb32c39","Computational modelling of failure in fibre reinforced plastic","Schipperen, J.H.A.","de Borst, R. (promotor)","2001","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:adbca9e7-08b9-4da3-9174-85c030dd1a15","http://resolver.tudelft.nl/uuid:adbca9e7-08b9-4da3-9174-85c030dd1a15","Mimetic spectral element method; a discretization of geometry and physics","Kreeft, J.J.","Bijl, H. (promotor); Gerritsma, M.I. (promotor)","2013","","","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:517916f3-9692-4e11-beb8-634fbfedf8d1","http://resolver.tudelft.nl/uuid:517916f3-9692-4e11-beb8-634fbfedf8d1","Three Dimensional Simulation of Fabric Draping","Bergsma, O.K.","de Jong, Th. (promotor)","1995","","composite; fabric; simulation; fabrication process; finite element analysis","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d0009bad-a9c9-4ada-b09f-6ef0322041a7","http://resolver.tudelft.nl/uuid:d0009bad-a9c9-4ada-b09f-6ef0322041a7","Development of a computer assisted toolbox for aerodynamic design of aircraft at subcritical conditions with application to three-surface and canard aircraft","Middel, J.","Torenbeek, E. (promotor)","1992","","","en","doctoral thesis","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:260cd874-c1ed-4155-bfdc-cf7fc3813ca6","http://resolver.tudelft.nl/uuid:260cd874-c1ed-4155-bfdc-cf7fc3813ca6","Aerodynamic Noise Reduction with Porous Materials: Aeroacoustics Investigations and Applications","Teruna, C. (TU Delft Wind Energy; TU Delft Flow Physics and Technology; TU Delft Aerospace Engineering)","Casalino, D. (promotor); Ragni, D. (copromotor); Avallone, F. (copromotor); Delft University of Technology (degree granting institution)","2022","Public annoyances due to noise emission in aviation and wind energy sectors are expected to become more severe in the near future with increasing number of civilian flights and wind turbine installations. Such trend demands for deeper investigations into the noise generation mechanisms and the means to mitigate them. This dissertation addresses two cases of flow-induced sound: 1) turbulent wake-body interaction, which leads to the combined tonal and broadband noise produced by the fan stage of an aircraft engine, and 2) turbulent boundary-layer trailing-edge noise that is responsible for the swishing noise from a wind turbine rotor. Although both mechanisms are inherently different, they both describe situations where noise is produced when turbulence encounters a discontinuity in the flow field, such as when turbulence in a freestream impinges a sharp leading edge or when turbulence in a boundary layer is scattered as it flows past a sharp trailing edge. The usage of permeable/porous materials at the edge of an aerodynamic body has been proposed as a solution since their flow permeability characteristic realises an intermediary region, alleviating the aforementioned discontinuities. However, there are questions that still need to be addressed. How exactly do these porous treatments mitigate the noise generation mechanisms? How do they affect the flow field in their vicinity? How should they be optimally designed and integrated? To help answering these questions, a high-fidelity lattice-Boltzmann method has been employed in the present work, with which detailed flow and acoustic analyses have been performed.","trailing-edge noise; leading-edge noise; aeroacoustics; porous materials; lattice-Boltzmann method","en","doctoral thesis","","978-94-6384-309-6","","","","","","","Aerospace Engineering","Flow Physics and Technology","Wind Energy","","",""
"uuid:d7a717a9-0ffa-4c06-b844-5a8183cbf684","http://resolver.tudelft.nl/uuid:d7a717a9-0ffa-4c06-b844-5a8183cbf684","An advection-based model to increase the temporal resolution of PIV time series","Scarano, F.; Moore, P.","","2012","A numerical implementation of the advection equation is proposed to increase the temporal resolution of PIV time series. The method is based on the principle that velocity fluctuations are transported passively, similar to Taylor’s hypothesis of frozen turbulence. In the present work, the advection model is extended to unsteady three-dimensional flows. The main objective of the method is that of lowering the requirement on the PIV repetition rate from the Eulerian frequency toward the Lagrangian one. The local trajectory of the fluid parcel is obtained by forward projection of the instantaneous velocity at the preceding time instant and backward projection from the subsequent time step. The trajectories are approximated by the instantaneous streamlines, which yields accurate results when the amplitude of velocity fluctuations is small with respect to the convective motion. The verification is performed with two experiments conducted at temporal resolutions significantly higher than that dictated by Nyquist criterion. The flow past the trailing edge of a NACA0012 airfoil closely approximates frozen turbulence, where the largest ratio between the Lagrangian and Eulerian temporal scales is expected. An order of magnitude reduction of the needed acquisition frequency is demonstrated by the velocity spectra of super-sampled series. The application to three-dimensional data is made with time-resolved tomographic PIV measurements of a transitional jet. Here, the 3D advection equation is implemented to estimate the fluid trajectories. The reduction in the minimum sampling rate by the use of super-sampling in this case is less, due to the fact that vortices occurring in the jet shear layer are not well approximated by sole advection at large time separation. Both cases reveal that the current requirements for time-resolved PIV experiments can be revised when information is poured from space to time. An additional favorable effect is observed by the analysis in the frequency domain whereby the spectrum becomes significantly less prone to aliasing error for the super-sampled data series.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b764abb1-6fe1-4f51-a709-b9e9aa5cf80a","http://resolver.tudelft.nl/uuid:b764abb1-6fe1-4f51-a709-b9e9aa5cf80a","Surface pressure and aerodynamic loads determination of a transonic airfoil based on particle image velocimetry","Ragni, D.; Ashok, A.; van Oudheusden, B.W.; Scarano, F.","","2009","The present investigation assesses a procedure to extract the aerodynamic loads and pressure distribution on an airfoil in the transonic flow regime from particle image velocimetry (PIV) measurements. The wind tunnel model is a two-dimensional NACA-0012 airfoil, and the PIV velocity data are used to evaluate pressure fields, whereas lift and drag coefficients are inferred from the evaluation of momentum contour and wake integrals. The PIV-based results are compared to those derived from conventional loads determination procedures involving surface pressure transducers and a wake rake. The method applied in this investigation is an extension to the compressible flow regime of that considered by van Oudheusden et al (2006 Non-intrusive load characterization of an airfoil using PIV Exp. Fluids 40 988–92) at low speed conditions. The application of a high-speed imaging system allows the acquisition in relatively short time of a sufficient ensemble size to compute converged velocity statistics, further translated in turbulent fluctuations included in the pressure and loads calculation, notwithstanding their verified negligible influence in the computation. Measurements are performed at varying spatial resolution to optimize the loads determination in the wake region and around the airfoil, further allowing us to assess the influence of spatial resolution in the proposed procedure. Specific interest is given to the comparisons between the PIV-based method and the conventional procedures for determining the pressure coefficient on the surface, the drag and lift coefficients at different angles of attack. Results are presented for the experiments at a free-stream Mach number M = 0.6, with the angle of attack ranging from 0? to 8?.","PIV; aerodynamic loads measurement; transonic airfoil","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5666b401-857e-4213-93f8-8de65e662231","http://resolver.tudelft.nl/uuid:5666b401-857e-4213-93f8-8de65e662231","DELFLY; insect inspired MAV","Bruggeman, B.; Groen, M.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:31e5d12f-286b-47df-bb87-353c4b684a06","http://resolver.tudelft.nl/uuid:31e5d12f-286b-47df-bb87-353c4b684a06","An H1(Ph)-Coercive Discontinuous Galerkin Formulation for The Poisson Problem: 1-D Analysis","Van der Zee, K.G.; Van Brummelen, E.H.; De Borst, R.","","2006","Coercivity of the bilinear form in a continuum variational problem is a fundamental property for finite-element discretizations: By the classical Lax–Milgram theorem, any conforming discretization of a coercive variational problem is stable; i.e., discrete approximations are well-posed and possess unique solutions, irrespective of the specifics of the underlying approximation space. Based on the prototypical one-dimensional Poisson problem, we establish in this work that most concurrent discontinuous Galerkin formulations for second-order elliptic problems represent instances of a generic conventional formulation and that this generic formulation is noncoercive. Consequently, all conventional discontinuous Galerkin formulations are a fortiori noncoercive, and typically their well-posedness is contingent on approximation-space-dependent stabilization parameters. Moreover, we present a new symmetric nonconventional discontinuous Galerkin formulation based on element Green’s functions and the data local to the edges. We show that the new discontinuous Galerkin formulation is coercive on the broken Sobolev space H1(Ph), viz., the space of functions that are elementwise in the H1 Sobolev space. The coercivity of the new formulation is supported by calculations of discrete inf-sup constants, and numerical results are presented to illustrate the optimal convergence behavior in the energy-norm and in the L2(?)-norm.","finite element method; discontinuous Galerkin; elliptic problems; coercivity","en","journal article","Society for Industrial and Applied Mathematics","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:b8fc08d5-a855-47be-9411-60d6fe06095e","http://resolver.tudelft.nl/uuid:b8fc08d5-a855-47be-9411-60d6fe06095e","Soda-can satellites; the CanSat project in the Netherlands worldwide","Motsyk, O.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c996e432-af42-430a-895a-dd4dff706a5a","http://resolver.tudelft.nl/uuid:c996e432-af42-430a-895a-dd4dff706a5a","Switchable static friction of piezoelectric composite—silicon wafer contacts","Van den Ende, D.A.; Fischer, H.R.; Groen, W.A.; Van der Zwaag, S.","","2013","The meso-scale surface roughness of piezoelectric fiber composites can be manipulated by applying an electric field to a piezocomposite with a polished surface. In the absence of an applied voltage, the tips of the embedded piezoelectric ceramic fibers are below the surface of the piezocomposite and a silicon wafer counter surface rests solely on the matrix region of the piezocomposite surface. When actuated, the piezoelectric ceramic fibers protrude from the surface and the wafer rests solely on these protrusions. A threefold decrease in engineering static friction coefficient upon actuation of the piezocomposite was observed: from ?*?=?1.65 to ?*?=?0.50. These experimental results could be linked to the change in contact surface area and roughness using capillary adhesion theory, which relates the adhesive force to the number and size of the contacting asperities for the different surface states","piezoceramics; polishing; silicon; stiction; surface roughness; surface states","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:9af0e833-de9e-4e78-9465-b2c656754a81","http://resolver.tudelft.nl/uuid:9af0e833-de9e-4e78-9465-b2c656754a81","Simulating Dynamic Stall in a 2D VAWT: Modeling strategy, verification and validation with Particle Image Velocimetry data","Ferreira, C.J.S.; Bijl, H.; Van Bussel, G.; Van Kuik, G.","","2007","","","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a09b0cc1-b685-4c2b-b3f5-7e5dc50b2fd6","http://resolver.tudelft.nl/uuid:a09b0cc1-b685-4c2b-b3f5-7e5dc50b2fd6","Improved constraints on models of glacial isostatic adjustment: A review of the contribution of ground-based geodetic observations","King, M.A.; Altamimi, Z.; Boehm, J.; Bos, M.; Dach, R.; Elosegui, P.; Fund, F.; Hernández-Pajares, M.; Lavallee, D.; Riva, E.M.","","2010","The provision of accurate models of Glacial Isostatic Adjustment (GIA) is presently a priority need in climate studies, largely due to the potential of the Gravity Recovery and Climate Experiment (GRACE) data to be used to determine accurate and continent-wide assessments of ice mass change and hydrology. However, modelled GIA is uncertain due to insufficient constraints on our knowledge of past glacial changes and to large simplifications in the underlying Earth models. Consequently, we show differences between models that exceed several mm/year in terms of surface displacement for the two major ice sheets: Greenland and Antarctica. Geodetic measurements of surface displacement offer the potential for new constraints to be made on GIA models, especially when they are used to improve structural features of the Earth’s interior as to allow for a more realistic reconstruction of the glaciation history. We present the distribution of presently available campaign and continuous geodetic measurements in Greenland and Antarctica and summarise surface velocities published to date, showing substantial disagreement between techniques and GIA models alike. We review the current state-of-the-art in ground-based geodesy (GPS, VLBI, DORIS, SLR) in determining accurate and precise surface velocities. In particular, we focus on known areas of need in GPS observation level models and the terrestrial reference frame in order to advance geodetic observation precision/accuracy toward 0.1 mm/year and therefore further constrain models of GIA and subsequent present-day ice mass change estimates.","Glacial isostatic adjustment (GIA); Ice sheet mass balance; Geodesy; Antarctica; Greenland; GPS; VLBI; DORIS; SLR","en","journal article","Springer","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:ba56768c-5407-47d4-bd57-c07e53eb7dbd","http://resolver.tudelft.nl/uuid:ba56768c-5407-47d4-bd57-c07e53eb7dbd","Revolutionary composite joining method; from an aerospace thesis research to founding a new company","Bergman, A.","","2014","In 2011, Peter Madlener started his graduation thesis at the Aerospace Engineering faculty on a new joining technology for composite sandwich panels. The promising results gained in this thesis led to the foundation of MOCS: a young company with the ambitious goal of introducing a revolutionary joining technology in the market. At this moment, MOCS is introducing its technology in the composite pipe industry. In this article you will read how MOCS was founded and how the technology it invented works.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:cf9119d3-8bbf-489b-b734-f25c4cd1402a","http://resolver.tudelft.nl/uuid:cf9119d3-8bbf-489b-b734-f25c4cd1402a","Robust flight control using incremental nonlinear dynamic inversion and angular acceleration prediction","Sieberling, S.; Chu, Q.P.; Mulder, J.A.","","2010","This paper presents a flight control strategy based on nonlinear dynamic inversion. The approach presented, called incremental nonlinear dynamic inversion, uses properties of general mechanical systems and nonlinear dynamic inversion by feeding back angular accelerations. Theoretically, feedback of angular accelerations eliminates sensitivity to model mismatch, greatly increasing the robust performance of the system compared with conventional nonlinear dynamic inversion. However, angular accelerations are not readily available. Furthermore, it is shown that angular acceleration feedback is sensitive to sensor measurement time delays. Therefore, a linear predictive filter is proposed that predicts the angular accelerations, solving the time delay and angular acceleration availability problem. The predictive filter uses only references and measurements of angular rates. Hence, the proposed control method makes incremental nonlinear dynamic inversion practically available using conventional inertial measurement units.","dynamic inversion; nonlinear dynamic inversion; incremental nonlinear dynamic inversion; NDI; INDI; feedback linearization; robust flight control; angular acceleration prediction","en","journal article","AIAA","","","","","","","","Aerospace Engineering","Control and Simulation Division","","","",""
"uuid:8035e9d3-4a88-4cfd-9ae7-de34706e2dee","http://resolver.tudelft.nl/uuid:8035e9d3-4a88-4cfd-9ae7-de34706e2dee","High efficiency, fully inkjet printed organic solar cells with freedom of design","Eggenhuisen, T.M.; Galagan, Y.; Biezemans, A.F.K.V.; Slaats, T.M.W.L.; Voorthuijzen, W.P.; Kommeren, S.; Shanmugam, S.; Teunissen, J.P.; Hadipour, A.; Verhees, W.J.H.; Veenstra, S.C.; Coenen, M.J.J.; Gilot, J.; Andriessen, R.; Groen, W.A.","","2015","The organic photovoltaics field is maturing and reaching a technology readiness level where the focus is on developing large scale fabrication methods. In this light, fully inkjet printed organic solar cells were demonstrated. Inkjet printing allows direct patterning of all the layers, including the electrodes, offering full freedom of design without the use of masks or structuring by hardware. The semitransparent front and back electrodes consist of PEDOT:PSS and conductive Ag fingers, avoiding the use of ITO. The inkjet printing of six functional layer demonstrated minimal losses in performance as compared to the lab-scale standard, spin coated devices. All-inkjet printed large area (>1 cm2) organic solar cells with power conversion efficiency of 4.1% deposited from environmentally friendly solvents in an air atmosphere are demonstrated for the first time. Organic solar cells were fabricated using industrial scale (512 nozzles) printheads, compatible with R2R technology. To prove the great advantage of inkjet printing as a digital technology allowing freedom of forms and designs, large area organic solar cells with different artistic shapes were demonstrated. Reported results confirm that inkjet printing has high potential for the processing of OPV, allowing quick changes in design as well as the materials.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:c7cd0759-777e-4cf9-8563-eaeaed56f1be","http://resolver.tudelft.nl/uuid:c7cd0759-777e-4cf9-8563-eaeaed56f1be","Analysis of the experimental and computational flow characteristics with respect to the augmented lift phenomenon caused by blade rotation","Van Rooij, R.P.J.O.M.; Arens, E.A.","","2007","","","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c7eddd40-7d9e-4d4a-87f9-3516f78f60d6","http://resolver.tudelft.nl/uuid:c7eddd40-7d9e-4d4a-87f9-3516f78f60d6","Investigating safety; an interview with professor John Stoop","Wamiti, L.; Motsyk, O.","Stoop, J. (contributor)","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a30c4645-bb4e-4054-83e3-4675d5667305","http://resolver.tudelft.nl/uuid:a30c4645-bb4e-4054-83e3-4675d5667305","Towards spatially constrained gust models","Bos, R.; Bierbooms, W.; Van Bussel, G.","","2014","With the trend of moving towards 10-20MW turbines, rotor diameters are growing beyond the size of the largest turbulent structures in the atmospheric boundary layer. As a consequence, the fully uniform transients that are commonly used to predict extreme gust loads are losing their connection to reality and may lead to gross over dimensioning. More suiting would be to represent gusts by advecting air parcels and posing certain physical constraints on size and position. However, this would introduce several new degrees of freedom that significantly increase the computational burden of extreme load prediction. In an attempt to elaborate on the costs and benefits of such an approach, load calculations were done on the DTU 10 MW reference turbine where a single uniform gust shape was given various spatial dimensions with the transverse wavelength ranging up to twice the rotor diameter (357 m). The resulting loads displayed a very high spread, but remained well under the level of a uniform gust. Moving towards spatially constrained gust models would therefore yield far less conservative, though more realistic predictions at the cost of higher computation time.","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:1f22fa6a-3e73-4189-83a4-ed1179d92d23","http://resolver.tudelft.nl/uuid:1f22fa6a-3e73-4189-83a4-ed1179d92d23","Can wind lidars measure turbulence?","Sathe, A.; Mann, J.; Gottschall, J.; Courtney, M.S.","","2011","Modeling of the systematic errors in the second-order moments of wind speeds measured by continuouswave (ZephIR) and pulsed (WindCube) lidars is presented. These lidars use the conical scanning technique to measure the velocity field. The model captures the effect of volume illumination and conical scanning. The predictions are compared with the measurements from the ZephIR, WindCube, and sonic anemometers at a flat terrain test site under different atmospheric stability conditions. The sonic measurements are used at several heights on a meteorological mast in combination with lidars that are placed on the ground. Results show that the systematic errors are up to 90% for the vertical velocity variance, whereas they are up to 70% for the horizontal velocity variance. For the ZephIR, the systematic errors increase with height, whereas for the WindCube, they decrease with height. The systematic errors also vary with atmospheric stability and are low for unstable conditions. In general, for both lidars, the model agrees well with the measurements at all heights and under different atmospheric stability conditions. For the ZephIR, the model results are improved when an additional low-pass filter for the 3-s scan is also modeled. It is concluded that with the current measurement configuration, these lidars cannot be used to measure turbulence precisely.","lidars; turbulence; wind","en","journal article","American Meteorological Society","","","","","","","2012-02-28","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:ae654160-7984-4667-aeba-29ec46b4d181","http://resolver.tudelft.nl/uuid:ae654160-7984-4667-aeba-29ec46b4d181","Estimating atmospheric stability from observations and correcting wind shear models accordingly","Holtslag, M.C.; Bierbooms, W.A.A.M.; Van Bussel, G.J.W.","","2014","Atmospheric stability strongly influences wind shear and thus has to be considered when performing load calculations for wind turbine design. Numerous methods exist however for obtaining stability in terms of the Obukhov length L as well as for correcting the logarithmic wind profile. It is therefore questioned to what extend the choice of adopted methods influences results when performing load analyses. Four methods found in literature for obtaining L, and five methods to correct the logarithmic wind profile for stability are included in the analyses (two for unstable, three for stable conditions). The four methods used to estimate stability from observations result in different PDF's of L, which in turn results in differences in estimated lifetime fatigue loads up to 81%. For unstable conditions hardly any differences are found when using either of the proposed stability correction functions, neither in wind shear nor in fatigue loads. For stable conditions however the proposed stability correction functions differ significantly, and the standard correction for stable conditions might strongly overestimate fatigue loads caused by wind shear (up to 15% differences). Due to the large differences found, it is recommended to carefully choose how to obtain stability and correct wind shear models accordingly.","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:64479473-1f94-4928-bcd3-e7a3af90af38","http://resolver.tudelft.nl/uuid:64479473-1f94-4928-bcd3-e7a3af90af38","Ecological Interface Design of a Tactical Airborne Separation Assistance Tool","Van Dam, S.; Mulder, M.; Van Paassen, M.M.","","2008","In a free-flight airspace environment, pilots have more freedom to choose user-preferred trajectories. An onboard pilot support system is needed that exploits travel freedom while maintaining spatial separation with other traffic. Ecological interface design is used to design an interface tool that assists pilots with the tactical planning of efficient conflict-free trajectories toward their destination. Desired pilot actions emerge from the visualization of workspace affordances in terms of a suitable description of aircraft (loco)motion. Traditional models and descriptions for aircraft motion cannot be applied efficiently for this purpose. Through functional modeling, more suitable locomotion models for trajectory planning are analyzed. As a result, a novel interface, the state vector envelope, is presented that is intended to provide the pilot with both low-level information, allowing direct action, and high-level information, allowing conflict understanding and situation awareness.","ecological interface design (EID); functional modeling; navigation interface; separation assistance","en","journal article","IEEE","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:0a0eca8a-3b65-4735-9b74-8f1373778533","http://resolver.tudelft.nl/uuid:0a0eca8a-3b65-4735-9b74-8f1373778533","Analysis of lateral dynamics and ride performance of the Superbus","Van Herk, S.; Terzi, A.; Ockels, W.J.","","2008","Vehicle handling and stability are very important at high speeds especially when the vehicle has a weight of about 6 times a normal luxury passenger car as in the case of the Superbus which travels at 250kph. In this paper the high speed performance of the Superbus will be analyzed. First the model will be discussed. Then, a number of the several analyses that were carried out will be discussed. These include single lane change and steering impulse. The simulations were done with a complete multibody model made in ADAMS, which accounts for all the major non-linearity’s of the actual vehicle, such as air springs and shock curves, suspension bump stops and Pacjeka tire model [1]. The results of these analyses show that the Superbus is a safe vehicle to drive at high speeds and still can be very comfortable.","Superbus","en","journal article","SAE International","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:d8a21448-7cd4-415e-84b2-d8a99f9f89dc","http://resolver.tudelft.nl/uuid:d8a21448-7cd4-415e-84b2-d8a99f9f89dc","The Vought XF5U 'flying lapjack' ; a forgotten prototype ahead of his time","Noordam, N.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:307532a7-cebe-4969-a171-b6ac382a5290","http://resolver.tudelft.nl/uuid:307532a7-cebe-4969-a171-b6ac382a5290","Active flap control on an aeroelastic wind turbine airfoil in gust conditions using both a CFD and an engineering model","Gillebaart, T.; Bernhammer, L.O.; Van Zuijlen, A.H.; Van Kuik, G.A.M.","","2014","","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:39e72035-c7a9-4ace-a316-a1079c6b2ea2","http://resolver.tudelft.nl/uuid:39e72035-c7a9-4ace-a316-a1079c6b2ea2","Design of guidance laws for lunar pinpoint soft landing","Guo, J.; Han, C.","","2009","Future lunar missions ask for the capability to perform precise Guidance, Navigation and Control (GNC) to the selected landing sites on the lunar surface. This paper studies the guidance issues for the lunar pinpoint soft landing problem. The primary contribution of this paper is the design of descent guidance law based on the Pontryagin maximum principle. The simulation shows that the proposed polynomial guidance law can achieve precise pinpoint landing. However it is sensitive to the selection of several parameters. Suggestions on lunar pinpoint soft landing strategies are also given according to the simulation results.","","en","journal article","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:7725ce82-7b8c-4b0d-a4a7-0319d29b251e","http://resolver.tudelft.nl/uuid:7725ce82-7b8c-4b0d-a4a7-0319d29b251e","Multi-pass light amplification for tomographic particle image velocimetry applications","Ghaemi, S.; Scarano, F.","","2010","The light source budget is a critical issue for tomographic particle image velocimetry (Tomo-PIV) systems due to its requirement for large illuminated volume and imaging at small apertures. In this work, a light amplification system based on the multi-pass concept is investigated for Tomo-PIV applications. The system design is performed on the basis of a theoretical model providing an estimation of the most important system parameters and above all the amplification gain. The multi-pass light amplification concept is verified experimentally by measuring the scattered light intensity across the illuminated volume. The results demonstrate a gain factor of 7 and 5 times in comparison with the single-pass and double-pass illumination approaches, respectively.","light amplification, laser, multi-pass reflection, tomographic PIV","en","journal article","Institute of Physics","","","","","","","","Aerospace Engineering","Department of Aerodynamics","","","",""
"uuid:83dd2c6b-c036-49ad-ae6d-579cb78e6113","http://resolver.tudelft.nl/uuid:83dd2c6b-c036-49ad-ae6d-579cb78e6113","Assessing receiver noise using GPS short baseline time series","Amiri-Simkooei, A.R.; Tiberius, C.C.J.M.","","2007","","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3ec4bc28-6bfa-4f28-9441-e493d8fd9ca0","http://resolver.tudelft.nl/uuid:3ec4bc28-6bfa-4f28-9441-e493d8fd9ca0","Post-impact performance of composites; Predicting Compression after Impact (CAI) in composite laminates","Esrall, F.","","2013","Impact damage has been known to seriously limit the performance of composite aircraft structures. In the preliminary design phase, tens of thousands of subparts need to be analyzed for impact. Over the years, many approaches have been proposed to study the creation of impact damage and to determine the residual strength of the structure. Although the progress has been significant, most of the existent methods are too prohibitive for large-scale implementation in the industry. In this thesis study, efficient analytical models were developed to study impact damage. These models will help the designer in the preliminary design phase to perform quick trade-offs and multiple analyses.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c9ef284b-2f62-4428-b5ec-ea6a30103137","http://resolver.tudelft.nl/uuid:c9ef284b-2f62-4428-b5ec-ea6a30103137","Convective rolls and heat transfer in finite-length Rayleigh-Bénard convection: A two-dimensional numerical study","Kenjere, S.; Hanjali¿, K.","","2000","","","en","journal article","American Physical Society","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9efa0245-e3be-4ff9-a6e4-33c49fa8dbd1","http://resolver.tudelft.nl/uuid:9efa0245-e3be-4ff9-a6e4-33c49fa8dbd1","Study of the fire resistant behavior of unfilled and carbon nanofibers reinforced polybenzimidazole coating for structural applications","Iqbal, H.M.S.; Stec, A.A.; Patel, P.; Bhowmik, S.; Benedictus, R.","","2013","With increasing interest in epoxy-based carbon fiber composites for structural applications, it is important to improve the fire resistant properties of these materials. The fire resistant performance of these materials can be improved either by using high performance epoxy resin for manufacturing carbon fiber composite or by protecting the previously used epoxy-based composite with some fire resistant coating. In this context, work is carried out to evaluate the fire resistance performance of recently emerged high performance polybenzimidazole (PBI) when used as a coating material. Furthermore, the effect of carbon nanofibers (CNFs) on fire resistant properties of inherently flame retardant PBI coating was studied. Thermogravimetric analysis of carbon/epoxy composite, unfilled PBI and nano-filled PBI shows that the carbon/epoxy composite maintained its thermal stability up to a temperature of 400°C and afterwards showed a large decrease in mass, while both unfilled PBI and nano-filled PBI have shown thermal stability up to a temperature of 575°C corresponding to only 11% weight loss. Cone calorimeter test results show that unfilled PBI coating did not improve the fire retardant performance of carbon/epoxy composite. Conversely, nano-filled PBI coating has shown a significant improvement in fire retardant performance of the carbon/epoxy composite in terms of increased ignition time, reduced average and peak heat release rate and reduced smoke and carbon monoxide emission. These results indicate that addition of carbon nanofibers to inherently flame retardant coating can significantly be helpful for improving the fire resistance performance of composite materials even with low coating thickness.","structural composite; fire resistant coating; carbon nanofibers","en","journal article","Wiley","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:d68a55f0-0758-4c78-8fd5-797b316a51e1","http://resolver.tudelft.nl/uuid:d68a55f0-0758-4c78-8fd5-797b316a51e1","Measurement of the body force field of plasma actuators","Kotsonis, M.; Ghaemi, S.; Veldhuis, L.; Scanorano, F.","","2011","A novel technique is proposed and investigated for the estimation of the body force field resulting from the operation of a dielectric barrier discharge plasma actuator. The technique relies on the measurement of the spatio-temporal evolution of the induced velocity field using high-speed particle image velocimetry (PIV). The technique has the advantage of providing spatial distribution of the body force vector field. A full Navier–Stokes term decomposition is applied on the evolving field along with additional closure norms in order to decouple the pressure gradient and body force terms. Results are compared with load-cell measurements of the direct reaction force and also momentum balance calculations based on the PIV field. Agreement between the different methods is observed. The data can easily be incorporated in computational flow solvers and also be used for validation and calibration of numerical plasma models.","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:c54b00c5-5fe1-4a20-bb19-f49c148e23e5","http://resolver.tudelft.nl/uuid:c54b00c5-5fe1-4a20-bb19-f49c148e23e5","Regional gravity modeling in terms of spherical base functions","Schmidt, M.; Fengler, M.; Mayer-Guerr, T.; Eicker, A.; Kusche, J.; Sanchez, L.; Han, S.C.","","2007","","Regional gravity modeling; Spherical radial base functions; Multi-resolution representation; Spherical wavelets; Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE)","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e9ec7f30-e75c-479e-8ffc-62bf052aee34","http://resolver.tudelft.nl/uuid:e9ec7f30-e75c-479e-8ffc-62bf052aee34","Shipping up to Boston! Experiencing what's like to study at one of the best engineering universities","Maere, P.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:365b0069-6200-4bf7-a386-18a40ec85e04","http://resolver.tudelft.nl/uuid:365b0069-6200-4bf7-a386-18a40ec85e04","Rock-hard coatings","Muller, M.","","2007","Aircraft jet engines have to be able to withstand infernal conditions. Extreme heat and bitter cold tax coatings to the limit. Materials expert Dr Ir. Wim Sloof fits atoms together to develop rock-hard coatings. The latest invention in this field is known as ceramic matrix composites. Sloof has signed an agreement with a number of parties to investigate this material further.","","en","journal article","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:447af3e0-ea75-4c82-a588-83e0f2a45a7e","http://resolver.tudelft.nl/uuid:447af3e0-ea75-4c82-a588-83e0f2a45a7e","The integrated curriculum; attracting, exciting and educating students to become highly qualified aerospace engineers","Kamp, A.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:66521c62-6cee-4c0f-9c23-57477b2ff625","http://resolver.tudelft.nl/uuid:66521c62-6cee-4c0f-9c23-57477b2ff625","Audi: The cost of enlightenment","Booij, M.","","2013","Being one of the premium German car brands, Audi has a long-standing “Leichtbau” tradition. Living up to the company motto “Vorsprung durch Technik”, Audi is currently working on implementing CFRP in cars such as the S7, A8 and R8. In a combined internship and thesis project in Neckarsulm, Germany, I assessed the performance and cost of Automated Fiber Placed composites, a new technology, opening up possibilities for cost e!ective manufacturing of highly effcient structures.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6f4b4b8d-37d3-4b55-9aea-96fe56a9129a","http://resolver.tudelft.nl/uuid:6f4b4b8d-37d3-4b55-9aea-96fe56a9129a","Unsung heroes of aviation; giving credit where credit is due","Broekhuizen, B.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ce39a088-d0e7-47ce-a64b-d32617b9d181","http://resolver.tudelft.nl/uuid:ce39a088-d0e7-47ce-a64b-d32617b9d181","Satellite gravity sees ice age footprints; using monthly maps of gravity field variations to find the geometry of ancient ice sheets","Van der Wal, W.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:32b1d63f-99ce-4a7d-be08-170f76c89b67","http://resolver.tudelft.nl/uuid:32b1d63f-99ce-4a7d-be08-170f76c89b67","Thermospheric mass density variations during geomagnetic storms and a prediction model based on the merging electric field","Liu, R.; Lühr, H.; Doornbos, E.; Ma, S.Y.","","2010","With the help of four years (2002–2005) of CHAMP accelerometer data we have investigated the dependence of low and mid latitude thermospheric density on the merging electric field, Em, during major magnetic storms. Altogether 30 intensive storm events (Dstmin 100 nT) are chosen for a statistical study. In order to achieve a good correlation Em is preconditioned. Contrary to general opinion, Em has to be applied without saturation effect in order to obtain good results for magnetic storms of all activity levels. The memory effect of the thermosphere is accounted for by a weighted integration of Em over the past 3 h. In addition, a lag time of the mass density response to solar wind input of 0 to 4.5 h depending on latitude and local time is considered. A linear model using the preconditioned Em as main controlling parameter for predicting mass density changes during magnetic storms is developed: ? =0.5Em+?amb, where ?amb is based on the mean density during the quiet day before the storm. We show that this simple relation predicts all storm-induced mass density variations at CHAMP altitude fairly well especially if orbital averages are considered.","ionosphere (ionosphere-magnetosphere interactions); meteorology and atmospheric dynamics (thermospheric dynamics)","en","journal article","European Geosciences Union (EGU)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:73f557e4-7e57-4237-91ad-b42a1e9df9e9","http://resolver.tudelft.nl/uuid:73f557e4-7e57-4237-91ad-b42a1e9df9e9","Steady state response of a granular layer to a moving load - A discrete model","Suiker, A.S.J.; Metrikine, A.V.; De Borst, R.","","2000","This paper discusses the steady state response of a rigidly supported, granular layer to a moving load. Accordingly, the dynamic behaviour of a ballast layer under an instantaneous train axle passage is simulated, where the rigid support reflects a substratum that is much stiffer than the ballast layer, e.g. ballast in a concrete railway tunnel or on a concrete railway foundation. The discrete nature of the layer is captured via a 9-cell square lattice. After deriving the equations of motion for the lattice, the long-wave approximation of the equations of motion is compared with the equations of motion for a continuum model. This leads to relations between the macroscopic constitutive parameters of the continuum and the microscopic constitutive parameters of the discrete lattice. Next, the boundary value problem is formulated and solved. The influence by the particle size, the damping characteristics and the load velocity on the layer response is demonstrated via a parametric study.","railway track; ballast behaviour; discrete lattice; moving load; wave propagation.","en","journal article","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f7a9d3ca-351b-4865-8519-41eee13d5c29","http://resolver.tudelft.nl/uuid:f7a9d3ca-351b-4865-8519-41eee13d5c29","Aircraft fires and passenger safety; examining the fire safety of structural composites in aircraft","Gransden, D.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:614025fe-e543-496c-a92d-cfe41110e4ba","http://resolver.tudelft.nl/uuid:614025fe-e543-496c-a92d-cfe41110e4ba","Visualization by PIV of dynamic stall on vertical axis wind turbine","Simao Ferreira, C.J.; van Kuik, G.A.M.; van Bussel, G.J.W.; Scarano, F.","","2008","","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f7e3316d-f551-468d-af10-6682a29f61d5","http://resolver.tudelft.nl/uuid:f7e3316d-f551-468d-af10-6682a29f61d5","Planetary, explorations symposium; robotic and manned missions to Mars and Jupiter","Van Zon, N.","","2014","This year, the 28th Space Department has the honor of organizing the Annual Symposium of the VSV ‘Leonardo da Vinci’. On March 4, 2014, a total of 564 engineering students and Aerospace professionals visited the symposium and enjoyed seven extremely inspiring talks and interactive discussions. This day, themed ‘Planetary Exploration’ focused on future and planned robotic and manned missions to Mars and Jupiter.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7aec19ec-fcbd-4268-a5c7-5a40320a7869","http://resolver.tudelft.nl/uuid:7aec19ec-fcbd-4268-a5c7-5a40320a7869","Effects of geometry and tip speed ratio on the HAWT blade's root flow","Akay, B.; Micallef, D.; Simao Ferreira, C.J.; Van Bussel, G.J.W.","","2014","In this study, the effect of the parameters playing a role in the root flow behavior of HAWT are only partly understood. To better reveal the root flow properties, this study presents the progression of HAWT blade root flow at two different blade geometries and at two different tip speed ratios. The effects of the geometry and the tip speed ratio on the root flow behavior and on the evolution of the root flow features are investigated. This study aims to answer the following questions: (i) What are the effects of the blade geometry and tip speed ratio on the root flow behavior? (ii) How are the blade wake and the root vortex evolution affected by the change of these parameters? The analysis of the velocity fields shows that the radial flow behavior changes with different blade geometries but a remarkable difference in the radial flow behavior is not observed with the change of tip speed ratio. The formation of the wake is different at three test cases because of different loading that the blades are encountered. From the circulation distribution along the blades, while a strong root vortex can be observed in Blade 1, the bound vorticity along Blade 2 builds up gradually when moving outboard, and do not show a trace of a strong root vortex.","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:95f24ee7-5881-4162-8917-33d9e9f6aecd","http://resolver.tudelft.nl/uuid:95f24ee7-5881-4162-8917-33d9e9f6aecd","When biology meets control theory","Damveld, H.; Abbink, D.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e729e378-29c0-4726-a991-b3e5a9e0ad77","http://resolver.tudelft.nl/uuid:e729e378-29c0-4726-a991-b3e5a9e0ad77","Motion tracking-enhanced MART for tomographic PIV","Novara, M.; Batenburg, K.J.; Scarano, F.","","2010","A novel technique to increase the accuracy of multiplicative algebraic reconstruction technique (MART) reconstruction from tomographic particle image velocimetry (PIV) recordings at higher seeding density than currently possible is presented. The motion tracking enhancement (MTE) method is based on the combined utilization of images from two or more exposures to enhance the reconstruction of individual intensity fields. The working principle is first introduced qualitatively, and the mathematical background is given that explains how the MART reconstruction can be improved on the basis of an improved first guess object obtained from the combination of non-simultaneous views reduced to the same time instant deforming the 3D objects by an estimate of the particle motion field. The performances of MTE are quantitatively evaluated by numerical simulation of the imaging, reconstruction and image correlation processes. The cases of two or more exposures obtained from time-resolved experiments are considered. The iterative application of MTE appears to significantly improve the reconstruction quality, first by decreasing the intensity of the ghost images and second, by increasing the intensity and the reconstruction precision for the actual particles. Based on computer simulations, the maximum imaged seeding density that can be dealt with is tripled with respect to the MART analysis applied to a single exposure. The analysis also illustrates that the maximum effect of the MTE method is comparable to that of doubling the number of cameras in the tomographic system. Experiments performed on a transitional jet at Re = 5000 apply the MTE method to double-frame recordings. The velocity measurement precision is increased for a system with fewer views (two or three cameras compared with four cameras). The ghost particles’ intensity is also visibly reduced although to a lesser extent with respect to the computer simulations. The velocity and vorticity field obtained from a three-camera reconstruction with MTE are equivalent to that from a four-camera analysis. Possible variants of the MTE algorithm are investigated based on a first guess obtained by average or by product of pseudo-simultaneous objects (PSO), which potentially offer a higher convergence rate.","tomographic PIV, MART, motion tracking enhancement (MTE)","en","journal article","Institute of Physics","","","","","","","","Aerospace Engineering","","","","",""
"uuid:301264d8-d014-4ca5-a463-d366f325d57b","http://resolver.tudelft.nl/uuid:301264d8-d014-4ca5-a463-d366f325d57b","An efficient and accurate approach to MTE-MART for time-resolved tomographic PIV","Lynch, K.P.; Scarano, F.","","2015","The motion-tracking-enhanced MART (MTE-MART; Novara et al. in Meas Sci Technol 21:035401, 2010) has demonstrated the potential to increase the accuracy of tomographic PIV by the combined use of a short sequence of non-simultaneous recordings. A clear bottleneck of the MTE-MART technique has been its computational cost. For large datasets comprising time-resolved sequences, MTE-MART becomes unaffordable and has been barely applied even for the analysis of densely seeded tomographic PIV datasets. A novel implementation is proposed for tomographic PIV image sequences, which strongly reduces the computational burden of MTE-MART, possibly below that of regular MART. The method is a sequential algorithm that produces a time-marching estimation of the object intensity field based on an enhanced guess, which is built upon the object reconstructed at the previous time instant. As the method becomes effective after a number of snapshots (typically 5–10), the sequential MTE-MART (SMTE) is most suited for time-resolved sequences. The computational cost reduction due to SMTE simply stems from the fewer MART iterations required for each time instant. Moreover, the method yields superior reconstruction quality and higher velocity field measurement precision when compared with both MART and MTE-MART. The working principle is assessed in terms of computational effort, reconstruction quality and velocity field accuracy with both synthetic time-resolved tomographic images of a turbulent boundary layer and two experimental databases documented in the literature. The first is the time-resolved data of flow past an airfoil trailing edge used in the study of Novara and Scarano (Exp Fluids 52:1027–1041, 2012); the second is a swirling jet in a water flow. In both cases, the effective elimination of ghost particles is demonstrated in number and intensity within a short temporal transient of 5–10 frames, depending on the seeding density. The increased value of the velocity space–time correlation coefficient demonstrates the increased velocity field accuracy of SMTE compared with MART.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:fe12e184-a52f-4da8-84eb-18f3dcba411a","http://resolver.tudelft.nl/uuid:fe12e184-a52f-4da8-84eb-18f3dcba411a","ATMOS UAV; high-tech startup with game-changing ideas","Hulsman, S.; De Groot, J.; Dokter, D.","","2014","Since the early years of aviation, aircraft manufacturers have taken multiple shots at aircraft that combine vertical take-off and landing (VTOL) with horizontal cruise flight - an idea that to this day continues to be technologically challenging. ATMOS UAV successfully applied this concept to unmanned aerial vehicles (UAVs) resulting in a portable, lightweight and practical system with unprecedented specifications.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a6ed6746-b456-4a30-9603-428991da4b2a","http://resolver.tudelft.nl/uuid:a6ed6746-b456-4a30-9603-428991da4b2a","Turbulent structure of high-amplitude pressure peaks within the turbulent boundary layer","Ghaemi, S.; Scarano, F.","","2013","","boundary layer structure; turbulent boundary layers","en","journal article","Cambridge University Press","","","","","","","2014-10-24","Aerospace Engineering","Aerospace Engineering","","","",""
"uuid:3c322ada-1f79-47d6-a60e-2aee6cc27ed2","http://resolver.tudelft.nl/uuid:3c322ada-1f79-47d6-a60e-2aee6cc27ed2","Studies of relativistic jets in active galactic nuclei with SKA","Agudo, I.; Bottcher, M.; Falcke, H.; Georganopoulos, M.; Ghisellini, G.; Giovannini, G.; Giroletti, M.; Gomez, J.L.; Gurvits, L.; Laing, R.; Lister, M.; Marti, J.M.; Meyer, E.T.; Mizuno, Y.; O'Sullivan, S.; Padovani, P.; Paragi, Z.; Perucho, M.; Schleicher, D.; Stawarz, L.; Vlahakis, N.; Wardle, J.","","2014","Relativistic jets in active galactic nuclei (AGN) are among the most powerful astrophysical objects discovered to date. Indeed, jetted AGN studies have been considered a prominent science case for SKA, and were included in several different chapters of the previous SKA Science Book (Carilli & Rawlings 2004). Most of the fundamental questions about the physics of relativistic jets still remain unanswered, and await high-sensitivity radio instruments such as SKA to solve them. These questions will be addressed specially through analysis of the massive data sets arising from the deep, all-sky surveys (both total and polarimetric flux) from SKA1. Wide-field verylong-baseline-interferometric survey observations involving SKA1 will serve as a unique tool for distinguishing between extragalactic relativistic jets and star forming galaxies via brightness temperature measurements. Subsequent SKA1 studies of relativistic jets at different resolutions will allow for unprecedented cosmological studies of AGN jets up to the epoch of re-ionization, enabling detailed characterization of the jet composition, magnetic field, particle populations, and plasma properties on all scales. SKA will enable us to study the dependence of jet power and star formation on other properties of the AGN system. SKA1 will enable such studies for large samples of jets, while VLBI observations involving SKA1 will provide the sensitivity for pc-scale imaging, and SKA2 (with its extraordinary sensitivity and dynamic range) will allow us for the first time to resolve and model the weakest radio structures in the most powerful radio-loud AGN.","","en","journal article","POS","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:1204d2fe-1301-4762-9986-ac40de4d9f89","http://resolver.tudelft.nl/uuid:1204d2fe-1301-4762-9986-ac40de4d9f89","From go-faster stripes to sliding tracksuits","Tigges, J.","","2012","Today sports and science go increasingly hand in hand. Together with private companies, sporting bodies and other research centres, TU Delft is involved in many innovative sports-related projects, particularly in water sports, where materials can be crucial.","sliding tracksuits","en","journal article","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:907d4789-cf56-4c78-87b6-209355fb4848","http://resolver.tudelft.nl/uuid:907d4789-cf56-4c78-87b6-209355fb4848","Global ionospheric and thermospheric response to the 5 April 2010 geomagnetic storm: An integrated data-model investigation","Lu, G.; Hagan, M.E.; Häusler, K.; Doornbos, E.N.; Bruinsma, S.; Anderson, B.J.; Korth, H.","","2014","We present a case study of the 5 April 2010 geomagnetic storm using observations and numerical simulations. The event was driven by a fast-moving coronal mass ejection and despite being a moderate storm with a minimum Dst near ?50 nT, the event exhibited elevated thermospheric density and surges of traveling atmospheric disturbances (TADs) more typically seen during major storms. The Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIMEGCM) was used to assess how these features were generated and developed during the storm. The model simulations gave rise to TADs that were highly nonuniform with strong latitude and longitude/local time dependence. The TAD phase speeds ranged from 640?m/s to 780?m/s at 400?km and were ~5% lower at 300?km and approximately 10–15% lower at 200?km. In the lower thermosphere around 100?km, the TAD signatures were nearly unrecognizable due to much stronger influence of upward propagating atmospheric tides. The thermosphere simulation results were compared to observations available from the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE), CHAllenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellites. Comparison with GOCE data shows that the TIMEGCM reproduced the cross-track winds over the polar region very well. The model-data comparison also revealed some differences, specifically, the simulations underestimated neutral mass density in the upper thermosphere above ~300?km and overestimated the storm recovery tome by 6 h. These discrepancies indicate that some heating or circulation dynamics and potentially cooling processes are not fully represented in the simulations, and also that updates to some parameterization schemes in the TIMEGCM are warranted.","thermospheric storm; ionospheric storm; TADs; neutral winds","en","journal article","American Geophysical Union","","","","","","","2015-06-09","Aerospace Engineering","Space Engineering","","","",""
"uuid:611cad60-7d1a-4c54-86d5-c345d922b936","http://resolver.tudelft.nl/uuid:611cad60-7d1a-4c54-86d5-c345d922b936","A mathematical analysis of physiological and morphological aspects of wound closure","Javierre, E.; Vermolen, F.J.; Vuik, C.; Van der Zwaag, S.","","2008","A computational algorithm to study the evolution of complex wound morphologies is developed based on a model of wound closure by cell mitosis and migration due to Adam [Math Comput Model 30(5–6):23–32, 1999]. A detailed analysis of the model provides estimated values for the incubation and healing times. Furthermore, a set of inequalities are defined which demarcate conditions of complete, partial and non-healing. Numerical results show a significant delay in the healing progress whenever diffusion of the epidermic growth factor responsible for cell mitosis is slower than cell migration. Results for general wound morphologies show that healing is always initiated at regions with high curvatures and that the evolution of the wound is very sensitive to physiological parameters.","Wound closure kinetics; EGF diffusion; Moving interface; Level set method","en","journal article","Springer","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures and Materials","","","",""
"uuid:41a0bf1a-ec58-47f6-8b63-79b5fe94b8f5","http://resolver.tudelft.nl/uuid:41a0bf1a-ec58-47f6-8b63-79b5fe94b8f5","Stratos II: Halfway to space; the next step in reaching space by a student-built rocket","Boeva, J.J.; Engelen, F.; Hermsen, R.; Olthof, H.; Motsyk, O.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a00101e7-45d9-4659-b344-4977ba89b814","http://resolver.tudelft.nl/uuid:a00101e7-45d9-4659-b344-4977ba89b814","Adapt or Perish: An Approach to Planning Under Deep Uncertainty","Walker, W.E.","","2015","Much policy advice is formulated implicitly assuming that the future can be predicted. A static policy is developed using a single ‘most likely’ future, often based on the extrapolation of trends; or a static ‘robust’ policy is developed that will produce acceptable outcomes in a range of plausible future worlds. However, if the future turns out to be different from the hypothesized future(s), the policy might fail. Furthermore, not only is the future highly uncertain, the conditions policymakers need to deal with are changing over time. This paper begins by defining what is meant by ‘deep uncertainty’. It then describes a new approach for planning under conditions of deep uncertainty that is based on creating a strategic vision of the future, committing to short-term actions, and establishing a framework to guide future actions. A policy that embodies these ideas allows for its dynamic adaptation over time to meet the changing circumstances.","deep uncertainty; robust decision making; adaptive policies; adaptation pathways; exploratory modeling and analysis","en","journal article","","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:f38bc7db-6a35-4214-b455-6832b0835861","http://resolver.tudelft.nl/uuid:f38bc7db-6a35-4214-b455-6832b0835861","Active stall control for large offshore horizontal axis wind turbines: A conceptual study considering different actuation methods","Pereira, R.; Van Bussel, G.J.W.; Timmer, W.A.","","2014","The increasing size of Horizontal Axis Wind Turbines and the trend to install wind farms further offshore demand more robust design options. If the pitch system could be eliminated, the availability of Horizontal Axis Wind Turbines should increase. This research investigates the use of active stall control to regulate power production in replacement of the pitch system. A feasibility study is conducted using a blade element momentum code and taking the National Renewable Energy Laboratory 5 MW turbine as baseline case. Considering half of the blade span is equipped with actuators, the required change in the lift coefficient to regulate power was estimated in Cl = 0:7. Three actuation technologies are investigated, namely Boundary Layer Transpiration, Trailing Edge Jets and Dielectric Barrier Discharge actuators. Results indicate the authority of the actuators considered is not sufficient to regulate power, since the change in the lift coefficient is not large enough. Active stall control of Horizontal Axis Wind Turbines appears feasible only if the rotor is re-designed from the start to incorporate active-stall devices.","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:156d6522-a8db-47c5-a85b-3341be2791af","http://resolver.tudelft.nl/uuid:156d6522-a8db-47c5-a85b-3341be2791af","Modeling and analysis of periodic orbits around a contact binary asteroid","Feng, J.; Noomen, R.; Visser, P.N.A.M.; Yuan, J.","","2015","The existence and characteristics of periodic orbits (POs) in the vicinity of a contact binary asteroid are investigated with an averaged spherical harmonics model. A contact binary asteroid consists of two components connected to each other, resulting in a highly bifurcated shape. Here, it is represented by a combination of an ellipsoid and a sphere. The gravitational field of this configuration is for the first time expanded into a spherical harmonics model up to degree and order 8. Compared with the exact potential, the truncation at degree and order 4 is found to introduce an error of less than 10 % at the circumscribing sphere and less than 1 % at a distance of the double of the reference radius. The Hamiltonian taking into account harmonics up to degree and order 4 is developed. After double averaging of this Hamiltonian, the model is reduced to include zonal harmonics only and frozen orbits are obtained. The tesseral terms are found to introduce significant variations on the frozen orbits and distort the frozen situation. Applying the method of Poincaré sections, phase space structures of the single-averaged model are generated for different energy levels and rotation rates of the asteroid, from which the dynamics driven by the 4×4 harmonics model is identified and POs are found. It is found that the disturbing effect of the highly irregular gravitational field on orbital motion is weakened around the polar region, and also for an asteroid with a fast rotation rate. Starting with initial conditions from this averaged model, families of exact POs in the original non-averaged system are obtained employing a numerical search method and a continuation technique. Some of these POs are stable and are candidates for future missions.","contact binary asteroid; spherical harmonics; averaging method; frozen orbits; poincaré sections; periodic orbits","en","journal article","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:90a04b22-6618-4a67-b340-d0a5ef279260","http://resolver.tudelft.nl/uuid:90a04b22-6618-4a67-b340-d0a5ef279260","Definition of the equivalent atmospheric stability for wind turbine fatigue load assessment","Holtslag, M.C.; Bierbooms, W.A.A.M.; Van Bussel, G.J.W.","","2014","In this paper the dependence of wind turbine fatigue loads on atmospheric stability is assessed. It is shown that fatigue loads depend strongly on stability, and highest loads occur for very unstable conditions. For a given hub height wind speed one can dene an equivalent atmospheric stability that corresponds to the same cumulative loads as if one performs an infinite amount of simulations for all stability conditions that may occur. It is shown that stability, conditionalised to hub height wind speed, is approximately normally distributed and the equivalent stability corresponds well to the mean stability for a given hub height wind speed. If one follows the IEC guidelines for offshore sites, neglecting atmospheric stability, one will compute higher cumulative lifetime fatigue loads (~ 10%). This overestimation is caused by conservatism in both wind shear and turbulence levels, which is explicitly shown for the turbulence levels analyzed in this paper","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:bdda72a3-8a9f-4b64-838b-c688eb18e66a","http://resolver.tudelft.nl/uuid:bdda72a3-8a9f-4b64-838b-c688eb18e66a","Through the web of subsidies; the road towards a more exciting thesis","Koerselman, E.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:96f4f149-de9f-451f-9a69-b9d66e4704a2","http://resolver.tudelft.nl/uuid:96f4f149-de9f-451f-9a69-b9d66e4704a2","Signal and noise in Gravity Recovery and Climate Experiment (GRACE) observed surface mass variations","Schrama, E.J.O.; Wouters, B.; Lavallée, D.A.","","2007","The Gravity Recovery and Climate Experiment (GRACE) product used for this study consists of 43 monthly potential coefficient sets released by the GRACE science team which are used to generate surface mass thickness grids expressed as equivalent water heights (EQWHs). We optimized both the smoothing radius and the level of approximation by empirical orthogonal functions (EOFs) and found that 6.25° and three modes are able to describe more than 73.5% of the variance. The EQWHs obtained by the EOF method describe all known variations in the continental hydrology, present?day ice sheet melting, and global isostatic adjustment. To assess the quality of the estimated grids, we constructed degree error spectra of EQWHs. We conclude that a significant part of the errors in GRACE can be explained by a scaling factor of 0.85 relative to degree error estimates provided by the GGM02C gravity model but that the present?day errors in the GRACE data are a factor 2 to 5 larger than forecasted by tide model differences and atmospheric pressure differences. Comparison to a network of 59 International GNSS Service (IGS) stations confined the filter parameter settings to three EOF modes and 5° or 6.25° smoothing radius. Residuals that remain after the EOF method do exhibit S2 aliasing errors and a semiannual continental hydrology signal contained in the Global Land Data Assimilation Systems (GLDAS) model. Further analysis of the residual EOF signal revealed alternating track correlation patterns that are partially explained by the GRACE covariance matrix and the handling of nuisance parameters in the GRACE data processing.","GRACE; temporary gravity; spherical harmonics; error analysis; empirical orthogonal functions; GPS","en","journal article","American Geophysical Union","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:ca3362f2-8e74-49a7-a4d2-6d7cd185b102","http://resolver.tudelft.nl/uuid:ca3362f2-8e74-49a7-a4d2-6d7cd185b102","A Fractionated Spacecraft System Assessment Tool Based on Lifecycle Simulation Under Uncertainty","Yao, W.; Chen, X.; Zhao, Y.; Van Tooren, M.J.L.","","2012","To comprehensively assess fractionated spacecraft, an assessment tool is developed based on lifecycle simulation under uncertainty driven by modular evolutionary stochastic models. First, fractionated spacecraft nomenclature and architecture are clarified, and assessment criteria are analyzed. The mean and standard deviation of risk adjusted lifecycle cost and net present value (NPV) are defined as assessment metrics. Second, fractionated spacecraft sizing models are briefly described, followed by detailed discussion on risk adjusted lifecycle cost and NPV models. Third, uncertainty sources over fractionated spacecraft lifecycle are analyzed and modeled with probability theory. Then the chronological lifecycle simulation process is expounded, and simulation modules are developed with object oriented methodology to build up the assessment tool. The preceding uncertainty models are integrated in these simulation modules, hence the random object status can be simulated and evolve with lifecycle timeline. A case study to investigate the fractionated spacecraft for a hypothetical earth observation mission is carried out with the proposed assessment tool, and the results show that fractionation degree and launch manifest have great influence on cost and NPV, and generally fractionated spacecraft is more advanced than its monolithic counterpart under uncertainty effect. Finally, some conclusions are given and future research topics are highlighted.","fractionated spacecraft; lifecycle simulation; assessment; uncertainty; lifecycle cost; net present value","en","journal article","Elsevier","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:78f7837c-e3a1-4889-9923-9846d10e7b90","http://resolver.tudelft.nl/uuid:78f7837c-e3a1-4889-9923-9846d10e7b90","The effect of GIA observables in the determination of upper mantle structures","Root, B.C.; Van der Wal, W.; Ebbing, J.","","2015","","","en","journal article","European Geosciences Union (EGU)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:91967a57-b6fb-4d74-a0a0-456df401d788","http://resolver.tudelft.nl/uuid:91967a57-b6fb-4d74-a0a0-456df401d788","Mean grain size mapping with single-beam echo sounders","Van Walree, P.A.; Ainslie, M.A.; Simons, D.G.","","2006","Echo energies of single-beam echo sounders are inverted for the sediment mean grain size via a combination of theoretical and empirical relationships. In situ measurements of the seafloor mass density have revealed the presence of a thin transition layer between the water and the sediment. Within this layer, which has a thickness of order 1 cm, the density continuously changes from the water value to the sediment bulk value. The associated impedance gradient affects the normal-incidence reflection coefficient at high frequencies, when the product of wave number and layer thickness is of order unity or higher. A mapping algorithm recognizing this gradient is applied to echo sounder data acquired in three different areas, and for five sounder frequencies between 12 and 200?kHz. Compared with a scheme that relies on the Rayleigh reflection coefficient of a discrete interface, an overall improvement of several phi units in the grain size mapping is achieved by taking the gradient into account. A necessary condition to reach agreement between the acoustic and the ground truth grain size is that the thickness of the transition layer increases with a decreasing grain size.","sediments; underwater sound; echo; acoustic impedance; acoustic wave reflection; Rayleigh waves","en","journal article","Acoustical Society of America","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:0052b1c7-92aa-40a0-9f2d-15af090b0295","http://resolver.tudelft.nl/uuid:0052b1c7-92aa-40a0-9f2d-15af090b0295","Falling to earth from the moon; interview with Apollo 15 astronaut Al Worden","Motsyk, O.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5779af2f-a1db-4fe0-a00e-e18f5d6d1db2","http://resolver.tudelft.nl/uuid:5779af2f-a1db-4fe0-a00e-e18f5d6d1db2","A new robust design for imperfection sensitive stiffened cylinders used in aerospace engineering","Liang, K.; Zhang, Y.; Sun, Q.; Ruess, M.","","2015","A knock-down factor is commonly used to take into account the obvious decline of the buckling load in a cylindrical shell caused by the inevitable imperfections. In 1968, NASA guideline SP-8007 gave knock-down factors which rely on a lower-bound curve taken from experimental data. Recent research has indicated that the NASA knock-down factors are inclined to produce very conservative estimations for the buckling load of imperfect shells, due to the limitations of the computational power and the experimental skills available five decades ago. A novel knock-down factor is proposed composed of two parts for the metallic stiffened cylinders. A deterministic study is applied to achieve the first part of the knock-down factor considering the measured geometric imperfection, the other types of imperfections are considered in the second part using a stochastic analysis. A smeared model is used to achieve the implementation of the measured geometric imperfection for the stiffened cylinder. This new robust and less conservative design for the stiffened cylinders is validated by using test results","knock-down factor; NASA guideline SP-8007; stiffened cylinder; stochastic analysis; smeared model","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:9cf6ee57-2b56-4aae-aedb-73f62fe3f875","http://resolver.tudelft.nl/uuid:9cf6ee57-2b56-4aae-aedb-73f62fe3f875","Development of the parashuttle; building from idea to product","Doensen, L.J.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f0e38597-a742-4e20-808d-93cc6726669b","http://resolver.tudelft.nl/uuid:f0e38597-a742-4e20-808d-93cc6726669b","Design and numerical investigation of swirl recovery vanes for the Fokker 29 propeller","Wang, Y.; Li, Q.; Eitelberg, G.; Veldhuis, L.L.M.; Kotsonis, M.","","2014","Swirl recovery vanes (SRVs) are a set of stationary vanes located downstream from a propeller, which may recover some of the residual swirl from the propeller, hoping for an improvement in both thrust and efficiency. The SRV concept design for a scaled version representing the Fokker 29 propeller is performed in this paper, which may give rise to a promotion in propulsive performance of this traditional propeller. Firstly the numerical strategy is validated from two aspects of global quantities and the local flow field of the propeller compared with experimental data, and then the exit flow together with the development of propeller wake is analyzed in detail. Three kinds of SRV are designed with multiple circular airfoils. The numerical results show that the swirl behind the propeller is recovered significantly with Model V3, which is characterized by the highest solidity along spanwise, for various working conditions, and the combination of rotor and vane produced 5.76% extra thrust at the design point. However, a lower efficiency is observed asking for a better vane design and the choice of a working point. The vane position is studied which shows that there is an optimum range for higher thrust and efficiency.","multiple circular airfoil; propellers; propulsion efficiency; swirl recovery vane; turboprop engine","en","journal article","Elsevier","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:fdb48355-34fc-4b7d-8dd5-b567c068d512","http://resolver.tudelft.nl/uuid:fdb48355-34fc-4b7d-8dd5-b567c068d512","Large-eddy simulation of cavitating nozzle flow and primary jet break-up","Örley, F.; Trummler, T.; Hickel, S.; Mihatsch, M.S.; Schmidt, S.J.; Adams, N.A.","","2015","We employ a barotropic two-phase/two-fluid model to study the primary break-up of cavitating liquid jets emanating from a rectangular nozzle, which resembles a high aspect-ratio slot flow. All components (i.e., gas, liquid, and vapor) are represented by a homogeneous mixture approach. The cavitating fluid model is based on a thermodynamic-equilibrium assumption. Compressibility of all phases enables full resolution of collapse-induced pressure wave dynamics. The thermodynamic model is embedded into an implicit large-eddy simulation (LES) environment. The considered configuration follows the general setup of a reference experiment and is a generic reproduction of a scaled-up fuel injector or control valve as found in an automotive engine. Due to the experimental conditions, it operates, however, at significantly lower pressures. LES results are compared to the experimental reference for validation. Three different operating points are studied, which differ in terms of the development of cavitation regions and the jet break-up characteristics. Observed differences between experimental and numerical data in some of the investigated cases can be caused by uncertainties in meeting nominal parameters by the experiment. The investigation reveals that three main mechanisms promote primary jet break-up: collapse-induced turbulent fluctuations near the outlet, entrainment of free gas into the nozzle, and collapse events inside the jet near the liquid-gas interface.","cavitation; large eddy simulations; gas liquid interfaces; nozzle flows; liquid surfaces","en","journal article","American Institute of Physics","","","","","","","2016-08-21","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:2cba26f8-a2df-4c79-a5a0-cf37fba911d7","http://resolver.tudelft.nl/uuid:2cba26f8-a2df-4c79-a5a0-cf37fba911d7","Improved Oceanographic Measurements from SAR Altimetry: Results and Scientific Roadmap from the ESA CryoSat Plus For Oceans Project","Cotton, D.; Andersen, O.; Boy, F.; Cancet, M.; Dinardo, S.; Gommenginger, C.; Egido, A.; Fernandes, J.; Nilo Garcia, P.; Lucas, B.; Moreau, T.; Naeije, M.C.; Scharroo, R.; Stenseng, L.; Benveniste, J.","","2015","","","en","journal article","European Geosciences Union (EGU)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:fbe64399-3143-4cbf-9643-ef18c3edcfa7","http://resolver.tudelft.nl/uuid:fbe64399-3143-4cbf-9643-ef18c3edcfa7","Preface","Sneeuw, N.; Kusche, J.","","2007","","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ccc6e7f3-3b21-4f05-a0ca-df8cad6d0ca0","http://resolver.tudelft.nl/uuid:ccc6e7f3-3b21-4f05-a0ca-df8cad6d0ca0","Optimization of sandwich composites fuselages under flight loads","Yan, C.; Bergsma, O.; Koussios, S.; Zu, L.; Beukers, A.","","2010","The sandwich composites fuselages appear to be a promising choice for the future aircrafts because of their structural efficiency and functional integration advantages. However, the design of sandwich composites is more complex than other structures because of many involved variables. In this paper, the fuselage is designed as a sandwich composites cylinder, and its structural optimization using the finite element method (FEM) is outlined to obtain the minimum weight. The constraints include structural stability and the composites failure criteria. In order to get a verification baseline for the FEManalysis, the stability of sandwich structures is studied and the optimal design is performed based on the analytical formulae. Then, the predicted buckling loads and the optimization results obtained froma FEMmodel are compared with that from the analytical formulas, and a good agreement is achieved. A detailed parametric optimal design for the sandwich composites cylinder is conducted. The optimization method used here includes two steps: the minimization of the layer thickness followed by tailoring of the fiber orientation. The factors comprise layer number, fiber orientation, core thickness, frame dimension and spacing. Results show that the two-step optimization is an effective method for the sandwich composites and the foam sandwich cylinder with core thickness of 5 mm and frame pitch of 0.5 m exhibits the minimum weight.","sandwich; composites; stability; optimization; ANOVA","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Materials and Manufacturing","","","",""
"uuid:b982573f-c4f1-4b2b-8c31-2addb6486155","http://resolver.tudelft.nl/uuid:b982573f-c4f1-4b2b-8c31-2addb6486155","Modelling plastic deformation of metals over a wide range of strain rates using irreversible thermodynamics","Huang, M.; Rivera-Diaz-del-Castillo, P.E.J.; Bouaziz, O.; Van der Zwaag, S.","","2009","Based on the theory of irreversible thermodynamics, the present work proposes a dislocation-based model to describe the plastic deformation of FCC metals over wide ranges of strain rates. The stress-strain behaviour and the evolution of the average dislocation density are derived. It is found that there is a transitional strain rate (~104 s-1) over which the phonon drag effects appear, resulting in a significant increase in the flow stress and the average dislocation density. The model is applied to pure Cu deformed at room temperature and at strain rates ranging from 10-5 to 106 s-1 showing good agreement with experimental results.","","en","journal article","Institute of Physics","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:db473be3-7bca-4e55-aacd-f46954d62c31","http://resolver.tudelft.nl/uuid:db473be3-7bca-4e55-aacd-f46954d62c31","Exploring the possibilities for star-tracker assisted calibration of the six individual GOCE accelerometers","Visser, P.N.A.M.","","2008","A method has been developed and tested for estimating calibration parameters for the six accelerometers on board the Gravity field and steady-state Ocean Circulation Explorer (GOCE) from star tracker observations. These six accelerometers are part of the gradiometer, which is the prime instrument on board GOCE. It will be shown that by taking appropriate combinations of observations collected by the accelerometers, by modeling acceleration terms caused by gravity gradients from an a priori low-degree spherical harmonic expansion, and by modeling rotational acceleration terms derived from star-tracker observations, scale factors of each of the accelerometers can be estimated for each axis. Simulated observations from a so-called end-to-end simulator were used to test the method. This end-to-end simulator includes a detailed model of the GOCE satellite, its instruments and instrument errors, and its environment. Results of the tests indicate that scale factors of all six accelerometers can be determined with an accuracy of around 0.01 for all components on a daily basis.","GOCE; Gradiometer; Accelerometers; Star-tracker; Calibration; Bias; Bias drift; Scale factor","en","journal article","Springer","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:64ebd20d-3633-4b00-8ee2-7cca4631c254","http://resolver.tudelft.nl/uuid:64ebd20d-3633-4b00-8ee2-7cca4631c254","Observations and analysis of phase scintillation of spacecraft signal on the interplanetary plasma","Molera Calvés, G.; Pogrebenko, S.V.; Cimò, G.; Duev, D.A.; Bocanegra-Bahamón, T.M.; Wagner, J.F.; Kallunki, J.; De Vicente, P.; Kronschnabl, G.; Haas, R.; Quick, J.; Maccaferri, G.; Colucci, G.; Wang, W.H.; Yang, W.J.; Hao, L.F.","","2014","Aims. The phase scintillation of the European Space Agency’s Venus Express (VEX) spacecraft telemetry signal was observed at X-band (? = 3.6 cm) with a number of radio telescopes of the European Very Long Baseline Interferometry (VLBI) Network in the period 2009–2013. Methods. We found a phase fluctuation spectrum along the Venus orbit with a nearly constant spectral index of ?2.42 ± 0.25 over the full range of solar elongation angles from 0° to 45°, which is consistent with Kolmogorov turbulence. Radio astronomical observations of spacecraft signals within the solar system give a unique opportunity to study the temporal behaviour of the signal’s phase fluctuations caused by its propagation through the interplanetary plasma and the Earth’s ionosphere. This gives complementary data to the classical interplanetary scintillation (IPS) study based on observations of the flux variability of distant natural radio sources. Results. We present here our technique and the results on IPS. We compare these with the total electron content for the line of sight through the solar wind. Finally, we evaluate the applicability of the presented technique to phase-referencing VLBI and Doppler observations of currently operational and prospective space missions.","scattering; plasmas; interplanetary medium; Sun: heliosphere; techniques: interferometric; astrometry","en","journal article","EDP Sciences","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:cd8cc8ac-a588-4943-9702-9f6b7133c2fd","http://resolver.tudelft.nl/uuid:cd8cc8ac-a588-4943-9702-9f6b7133c2fd","Meet the aggies; internship experience at the Texas A&M University","Shukla, A.","","2013","“Welcome to the United States of America” the lines I had heard quite a few times in movies and sitcoms. Yet here I was listening to it, jet lagged and sleep deprived after roughly 24 hrs of flying, having just completed the immigration clearance at George Bush International Airport, Houston.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b2b844a6-e1a1-4611-b0f2-2f3c76ca044c","http://resolver.tudelft.nl/uuid:b2b844a6-e1a1-4611-b0f2-2f3c76ca044c","Unsteady aerodynamic forces estimation on a square cylinder by TR-PIV","Kurtulus, D.F.; Scarano, F.; David, L.","","2007","","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8bcb8def-9ec5-432c-b2bf-297e976b950b","http://resolver.tudelft.nl/uuid:8bcb8def-9ec5-432c-b2bf-297e976b950b","Instantaneous planar pressure determination from PIV in turbulent flow","De Kat, R.; Van Oudheusden, B.W.","","2011","This paper deals with the determination of instantaneous planar pressure fields from velocity data obtained by particle image velocimetry (PIV) in turbulent flow. The operating principles of pressure determination using a Eulerian or a Lagrangian approach are described together with theoretical considerations on its expected performance. These considerations are verified by a performance assessment on a synthetic flow field. Based on these results, guidelines regarding the temporal and spatial resolution required are proposed. The interrogation window size needs to be 5 times smaller than the flow structures and the acquisition frequency needs to be 10 times higher than the corresponding flow frequency (e.g. Eulerian time scales for the Eulerian approach). To further assess the experimental viability of the pressure evaluation methods, stereoscopic PIV and tomographic PIV experiments on a square cylinder flow (ReD = 9,500) were performed, employing surface pressure data for validation. The experimental results were found to support the proposed guidelines.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b7d791b8-9127-49f2-9407-0625f5c54875","http://resolver.tudelft.nl/uuid:b7d791b8-9127-49f2-9407-0625f5c54875","Experimental comparison of a wind-turbine and of an actuator-disc near wake","Lignarolo, L.; Ragni, D.; Simao Ferreira, C.J.; Van Bussel, G.J.W.","","2016","The actuator disc (AD) model is commonly used to simplify the simulation of horizontal-axis wind-turbine aerodynamics. The limitations of this approach in reproducing the wake losses in wind farm simulations have been proven by a previous research. The present study is aimed at providing an experimental analysis of the near-wake turbulent flow of a wind turbine (WT) and a porous disc, emulating the actuator disc numerical model. The general purpose is to highlight the similarities and to quantify the differences of the two models in the near-wake region, characterised by the largest discrepancies. The velocity fields in the wake of a wind turbine model and a porous disc (emulation of the actuator disc numerical model) have been measured in a wind tunnel using stereo particle image velocimetry. The study has been conducted at low turbulence intensity in order to separate the problems of the flow mixing caused by the external turbulence and the one caused by the turbulence induced directly by the AD or the WT presence. The analysis, as such, showed the intrinsic differences and similarities between the flows in the two wakes, solely due to the wake-induced flow, with no influence of external flow fluctuations. The data analysis provided the time-average three-component velocity and turbulence intensity fields, pressure fields, rotor and disc loading, vorticity fields, stagnation enthalpy distribution, and mean-flow kinetic-energy fluxes in the shear layer at the border of the wake. The properties have been compared in the wakes of the two models. Even in the absence of turbulence, the results show a good match in the thrust and energy coefficient, velocity, pressure, and enthalpy fields between wind turbine and actuator disc. However, the results show a different turbulence intensity and turbulent mixing. The results suggest the possibility to extend the use of the actuator disc model in numerical simulation until the very near wake, provided that the turbulent mixing is correctly represented.","","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:88e80c47-c534-4eed-a639-512fc37fcda2","http://resolver.tudelft.nl/uuid:88e80c47-c534-4eed-a639-512fc37fcda2","Dynamic pitching effect on a laminar separation bubble","Nati, A.; De Kat, R.; Scarano, F.; Van Oudheusden, B.W.","","2015","The unsteady effect of a periodic pitching motion on the characteristic of a laminar separation bubble on the suction side of a SD7003 aerofoil is investigated by means of time-resolved planar and tomographic particle image velocimetry. The measurements provide information on the separation, transition and vortex roll-up onset as well as the spanwise distribution of vortical structures, for both the dynamic pitching between 4° and 8° and corresponding cases at a static pitch angle. During pitching, a clear hysteresis behaviour is observed for the vortex roll-up position and shedding frequency, showing a strongly delayed recovery of the shear layer with respect to the steady aerofoil case. The development of the shear layer transition exhibits initially 2D Kelvin–Helmholtz rollers that are interrupted, forming ?-shaped rollers, which eventually evolve into 3D arch-shaped hairpin structures. The 3D analysis of undulated rollers allowed the determination of the rollers streamwise spatial separation for both static and pitching aerofoil cases.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:85fdac44-ca9e-4421-b2e2-bb9b8ee509d8","http://resolver.tudelft.nl/uuid:85fdac44-ca9e-4421-b2e2-bb9b8ee509d8","The Einstein relation in quantum wires of III-V, ternary, and quaternary materials in the presence of light waves: Simplified theory, relative comparison, and suggestion for experimental determination","Ghatak, K.P.; Bhattacharya, S.; Bhowmik, S.; Benedictus, R.; Choudhury, S.","","2008","We study the Einstein relation for the diffusivity to mobility ratio (DMR) in quantum wires (QWs) of III-V, ternary, and quaternary materials in the presence of light waves, whose unperturbed energy band structures are defined by the three band model of Kane. It has been found, taking n-InAs, n-InSb, n-Hg1?xCdxTe, n-In1?xGaxAsyP1?y lattice matched to InP as examples, that the respective DMRs exhibit decreasing quantum step dependence with the increasing film thickness, decreasing electron statistics, increasing light intensity and wavelength, with different numerical values. The nature of the variations is totally band structure dependent and is influenced by the presence of the different energy band constants. The strong dependence of the DMR on both the light intensity and the wavelength reflects the direct signature of the light waves which is in contrast as compared to the corresponding QWs of the said materials in the absence of photoexcitation. The classical equation of the DMR in the absence of any field has been obtained as a special case of the present analysis under certain limiting conditions and this is the indirect test of the generalized formalism. We have suggested an experimental method of determining the DMR in QWs of degenerate materials having arbitrary dispersion laws and our results find six applications in the field of quantum effect devices.","band structure; cadmium compounds; carrier mobility; diffusion; dispersion relations; gallium arsenide; gallium compounds; III-V semiconductors; indium compounds; mercury compounds; semiconductor quantum wires; ternary semiconductors","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:0f938f54-7f7e-4d30-8c9c-6654d23fdf87","http://resolver.tudelft.nl/uuid:0f938f54-7f7e-4d30-8c9c-6654d23fdf87","Improving the d33 and g33 properties of 0-3 piezoelectric composites by dielectrophoresis","Van den Ende, D.A.; Bory, B.F.; Groen, W.A.; Van der Zwaag, S.","","2010","Composites of piezoelectric particles in a polymer matrix with enhanced properties in the poling direction were prepared by dielectrophoretic alignment of the particles. The effect of processing parameters such as the amplitude and frequency of the applied electric field and the viscosity of the matrix on the dielectric and piezoelectric properties of the cured composite were demonstrated for a composite with a PZT volume fraction of 0.2. The amount of structuring could be correlated to the dielectric and piezoelectric properties of the composite through the order parameter for the average particle chain orientation, which was derived from image analysis of the microstructure. The piezoelectric properties of the aligned composites can be described with a new model for composites containing particles arranged into chains. The model predictions are in good agreement with the experimental results.","dielectric polarisation; electrophoresis; filled polymers; lead compounds; piezoelectric materials","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:4d608478-0edc-4245-92b3-20e4520263fe","http://resolver.tudelft.nl/uuid:4d608478-0edc-4245-92b3-20e4520263fe","Isogeometric design of elastic arches for maximum fundamental frequency","Nagy, A.P.; Abdalla, M.M.; Gürdal, Z.","","2010","The isogeometric paradigm is aimed at unifying the geometric and analysis descriptions of engineering problems. This unification is brought about by employing the same basis functions describing the geometry to approximate the physical response. Non-uniform rational B-splines (NURBS) are commonly used for this purpose and are adopted in the present work for the design of elastic arches. Design for optimal shape and stiffness distribution is considered. Manufacturing constraints are imposed on shape and sizing variables. Shape changes are represented by altering spatial location of the control points and the associated weights. Sizing variables, that control the stiffness distribution, are defined at the control points and interpolated using the same spline basis functions. Since analysis, sizing, and shape design share the same underlying description, consistent discrete sensitivities can be easily evaluated analytically, greatly improving the performance of the optimisation process. While sizing should reflect the influence of local stress states, shape design is preferably performed at a global level. Thus, a multilevel approach is utilised, where shape design is carried out at a coarser level. Projecting the shape design sensitivities bridges the gap between the different levels. A variational formulation of essential manufacturing constraints for sizing and shape optimal design is introduced. The design framework is applied to fundamental frequency maximisation problems.","isogeometric design; NURBS; continuous sizing; multilevel shape design; manufacturing constraints","en","journal article","Springer Verlag","","","","","","","","Aerospace Engineering","Aerospace Structures & Design Methodology","","","",""
"uuid:af18eec1-1c7a-4898-be31-e65ad5f5ae7c","http://resolver.tudelft.nl/uuid:af18eec1-1c7a-4898-be31-e65ad5f5ae7c","Dutch design has major influence on Beijing's airports; short outline of the features of NACO's winning airports designs","Faber, K.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1e55ca20-c0b2-449f-904b-4921d04189ae","http://resolver.tudelft.nl/uuid:1e55ca20-c0b2-449f-904b-4921d04189ae","Optical coherence elastography for measuring the deformation within glass fiber composite","Liu, P.; Groves, R.M.; Benedictus, R.","","2014","Optical coherence elastography (OCE) has been applied to the study of microscopic deformation in biological tissue under compressive stress for more than a decade. In this paper, OCE has been extended for the first time, to the best of our knowledge, to deformation measurement in a glass fiber composite in the field of nondestructive testing. A customized optical coherence tomography system, combined with a mechanical loading setup, was developed to provide pairs of prestressed and stressed structural images. The speckle tracking algorithm, based on 2D cross correlation, was used to estimate the local displacements in micrometer scale. The algorithm was first evaluated by a test of rigid body translation. Then the experiments were carried out with the tensile test and three point bending on a set of glass fiber composites. The structural features and structural variations during the mechanical loadings are clearly observed with the presented displacement maps. The advantages and prospects for OCE application on glass fiber composites are discussed at the end of this paper.","optical coherence tomography; tomographic image processing; speckle imaging; nondestructive testing","en","journal article","Optical Society of America","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:4e87df6c-bc7c-4fb0-83a1-72a19aad2177","http://resolver.tudelft.nl/uuid:4e87df6c-bc7c-4fb0-83a1-72a19aad2177","The value of noise at regional airports; the case of Rotterdam The Hague Airport","Wan Mohamed, W.M.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2de031f6-140b-49cb-aa83-27653c0c81c7","http://resolver.tudelft.nl/uuid:2de031f6-140b-49cb-aa83-27653c0c81c7","A parametric study on supersonic/hypersonic flutter behavior of aero-thermo-elastic geometrically imperfect curved skin panel","Abbas, L.K.; Rui, X.; Marzocca, P.; Abdalla, M.; De Breuker, R.","","2011","In this paper, the effect of the system parameters on the flutter of a curved skin panel forced by a supersonic/hypersonic unsteady flow is numerically investigated. The aeroelastic model investigated includes the third-order piston theory aerodynamics for modeling the flow-induced forces and the Von Kármán nonlinear strain-displacement relation in conjunction with the Kirchhoff plate hypothesis for the panel structural modeling. Structural non-linearities are considered and are due to the non-linear coupling between out-of-plane bending and in-plane stretching. The effects of thermal degradation and Kelvin’s model of structural damping independent on time and temperature are also considered. The aero-thermo-elastic governing equations are developed from the geometrically imperfect non-linear theory of infinitely long two-dimensional curved panels. Computational analysis and discussion of the finding along with pertinent conclusions are presented.","","en","journal article","Springer-Verlag","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e67e358e-13db-4a1e-b12c-21a5a9e20438","http://resolver.tudelft.nl/uuid:e67e358e-13db-4a1e-b12c-21a5a9e20438","History of aviation safety; the satisfying sighs of relief due to developments in Aviation safety","Stoop, J.A.A.M.","","2014","”Aviation safety is an Integral part of my career. Being part of TU Delft’s impressive record of research on Aviation safety, my career has been with a sense of purpose and a responsibility to equip students to deal with the status quo challenges on Aviation safety, developments, Investigations and Optimizations. As I retire from the faculty with a gratifying sigh of relief, It’s a pleasure for me write this article on my experience and career along the progressive stages of Aviation safety.“","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ec815407-1f01-40ca-9d58-0d41cc9b6d80","http://resolver.tudelft.nl/uuid:ec815407-1f01-40ca-9d58-0d41cc9b6d80","The evolution of space stations; call for a discuss on the ISS","Sanders, T.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a4d08691-29b2-4bab-a20d-818987099ffa","http://resolver.tudelft.nl/uuid:a4d08691-29b2-4bab-a20d-818987099ffa","Building Russia's Silicon Valley; interview with the head of the Skolkovo's Space cluster, Sergei Zhukov","Motsyk, O.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a6ba7dc2-93b0-4745-b5a5-41788aefe4c9","http://resolver.tudelft.nl/uuid:a6ba7dc2-93b0-4745-b5a5-41788aefe4c9","Piezoelectric and mechanical properties of novel composites of PZT and a liquid crystalline thermosetting resin","Van Den Ende, D.A.; De Almeida, P.; Van Der Zwaag, S.","","2007","","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5e36bc9b-ee76-4200-af92-b5dfe56e6413","http://resolver.tudelft.nl/uuid:5e36bc9b-ee76-4200-af92-b5dfe56e6413","Direct numerical simulation analysis of local flow topology in a particle-laden turbulent channel flow","Bijlard, M.J.; Oliemans, R.V.A.; Portela, L.M.; Ooms, G.","","2010","The results of point-particle Eulerian–Lagrangian direct numerical simulation (DNS) calculations of dilute particle-laden turbulent channel flow are used to study the effect of the particles on the local flow topology. It is found that in the viscous sublayer, the flow becomes increasingly more two-dimensional as the two-way coupling effect (due to interaction between particles and fluid flow) increases with increasing particle load. Beyond the viscous sublayer the modifications in flow topology are not strongly related to the preferential concentration of particles in the flow field, which is in contrast to previous channel flow simulations. The effect of particles on the turbulent flow beyond the viscous sublayer is mostly a result of the overall changing near-wall dynamics of the fluid flow.","","en","journal article","Cambridge University Press","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:6613f10d-d395-4534-a373-0422756e4dff","http://resolver.tudelft.nl/uuid:6613f10d-d395-4534-a373-0422756e4dff","Desdemona and a ticket to space; training for space flight in a 3g motion simulator","Wouters, M.","","2014","On October 5, 2013, Marijn Wouters and two other contestants of a nation-wide competition ‘Nederland Innoveert’ underwent a space training exercise. One by one, the trainees were pushed to their limits in the Desdemona motion simulator, an experience that mimicked the Space Expedition Corporation (SXC) space flight envelope. The ultimate goal: training for an actual mission, the 1st prize in the aforementioned competition.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3570eee7-45e7-4bfc-b45f-2229c0236ae3","http://resolver.tudelft.nl/uuid:3570eee7-45e7-4bfc-b45f-2229c0236ae3","Hummingbird's-eye view for the US military","Sabbapathy, L.","","2013","The US research defense agency, DARPA has once again breached the innovation barrier by developing a miniature flying robot project, a humming bird mimicking Nano Air Vehicle (NAV) with AeroVironment Inc. This bio-inspired flying machine has been recognized among TIME Magazine’s 2011 best fifty inventions. The drone copies a humming bird to the extent of flying backwards, hover & rotate - all accomplished with the maneuverability of just two flapping wings.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:bcf47569-1d86-46f5-bb0a-ffb5ea233eef","http://resolver.tudelft.nl/uuid:bcf47569-1d86-46f5-bb0a-ffb5ea233eef","GRACE gravity observations constrain Weichselian ice thickness in the Barents Sea","Root, B.C.; Tarasov, L.; Van der Wal, W.","","2015","The Barents Sea is subject to ongoing postglacial uplift since the melting of the Weichselian ice sheet that covered it. The regional ice sheet thickness history is not well known because there is only data at the periphery due to the locations of Franz Joseph Land, Svalbard, and Novaya Zemlya surrounding this paleo ice sheet. We show that the linear trend in the gravity rate derived from a decade of observations from the Gravity Recovery and Climate Experiment (GRACE) satellite mission can constrain the volume of the ice sheet after correcting for current ice melt, hydrology, and far-field gravitational effects. Regional ice-loading models based on new geologically inferred ice margin chronologies show a significantly better fit to the GRACE data than that of ICE-5G. The regional ice models contain less ice in the Barents Sea than present in ICE-5G (5–6.3?m equivalent sea level versus 8.5?m), which increases the ongoing difficulty in closing the global sea level budget at the Last Glacial Maximum.","","en","journal article","American Geophysical Union","","","","","","","2015-11-13","Aerospace Engineering","Space Engineering","","","",""
"uuid:94bbe5b5-891e-425d-a6cf-81362ed2a7ca","http://resolver.tudelft.nl/uuid:94bbe5b5-891e-425d-a6cf-81362ed2a7ca","The role of continuity in residual-based variational multiscale modeling of turbulence","Akkerman, I.; Bazilevs, Y.; Calo, V.M.; Hughes, T.J.R.; Hulshoff, S.","","2007","This paper examines the role of continuity of the basis in the computation of turbulent flows. We compare standard finite elements and non-uniform rational B-splines (NURBS) discretizations that are employed in Isogeometric Analysis (Hughes et al. in Comput Methods Appl Mech Eng, 194:4135–4195, 2005). We make use of quadratic discretizations that are C 0-continuous across element boundaries in standard finite elements, and C 1-continuous in the case of NURBS. The variational multiscale residual-based method (Bazilevs in Isogeometric analysis of turbulence and fluid-structure interaction, PhD thesis, ICES, UT Austin, 2006; Bazilevs et al. in Comput Methods Appl Mech Eng, submitted, 2007; Calo in Residual-based multiscale turbulence modeling: finite volume simulation of bypass transition. PhD thesis, Department of Civil and Environmental Engineering, Stanford University, 2004; Hughes et al. in proceedings of the XXI international congress of theoretical and applied mechanics (IUTAM), Kluwer, 2004; Scovazzi in Multiscale methods in science and engineering, PhD thesis, Department of Mechanical Engineering, Stanford Universty, 2004) is employed as a turbulence modeling technique. We find that C 1-continuous discretizations outperform their C 0-continuous counterparts on a per-degree-of-freedom basis. We also find that the effect of continuity is greater for higher Reynolds number flows.","Incompressible flows; Finite elements; NURBS; NavierStokes equations; Boundary layers; Turbulent channel flows; Residual-based turbulence modeling; Isogeometric Analysis; Continuity of discretization; Variational multiscale formulation","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:abd45057-1120-4b33-9e45-b4adad598964","http://resolver.tudelft.nl/uuid:abd45057-1120-4b33-9e45-b4adad598964","Test method to assess interface adhesion in composite bonding","Teixeira de Freitas, S.; Sinke, J.","","2015","This paper introduces a new type of peel tests dedicated to composite bonding: Composite Peel Tests. This test is inspired on the standard floating roller peel test widely used for metal bonding. The aim of this study is to investigate the potential of the Composite Peel Test to assess interface adhesion in composite bonded structures. To this end, peel tests were performed with nine different types of adhesives and at two environmental temperatures, room temperature and +80°C. The results were compared with the standard floating roller peel tests with Aluminium adherends. The results show that when using the Composite Peel Test good interface adhesion results either in cohesive failure of the adhesive or intra-laminar failure of the composite, while bad adhesion results in adhesive failure. In most cases of good interface adhesion, increasing the temperature favors cohesive failure of the adhesive in detriment of intra-laminar failure of the composite. Peel strengths can be used as a quality indicator of interface adhesion only if using exactly the same type of flexible adherend (peeling-off member). Nevertheless, if cohesive failure is the dominant failure mode, the comparison between adhesives’ peel strength is consistent disregarding of the type of peel-off adherend. Composite Peel Tests are suitable to assess interface adhesion of composite bonded structures.","peel tests; composites; adhesion; interface; composite bonding; OA-Fund TU Delft","en","journal article","BioMed Central","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:2203ff57-42dd-4b17-b440-087f65891528","http://resolver.tudelft.nl/uuid:2203ff57-42dd-4b17-b440-087f65891528","The other drones; looking at the other drone use possibilities","Klein, R.","","2014","Most people will think of the MQ-9 Reaper, when mentioning drones. This is the drone that is used by the United States Air Force and the CIA in Pakistan, Yemen and Somalia to kill terrorists. Most of the time, these drones are mentioned in the news for their collateral damage. In 2013 alone, the United States estimated that 271 people died from drone strikes around the world [1]. The government claims that approximately one in every nine to 10 deaths is a civilian. But drones are not only used to kill. In fact, most drones are used for peaceful purposes around the world.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4c96ac4d-4279-4c25-97d5-a6bf0d29d4e7","http://resolver.tudelft.nl/uuid:4c96ac4d-4279-4c25-97d5-a6bf0d29d4e7","Present Day Regional Mass Loss of Greenland Observed with Satellite Gravimetry","Schrama, E.J.O.; Wouters, B.; Vermeersen, L.L.A.","","2011","This paper summarizes results obtained for Greenland’s mass balance observed with NASA’s GRACE mission. We estimate a Greenland ice sheet mass loss at ?201 ± 19 Gt/year including a discernible acceleration of ?8 ± 7 Gt/year2 between March 2003 and February 2010. The mass loss of glacier systems on the South East of Greenland has slowed down while the mass loss increases toward the North along the West side of Greenland. The mass balance can be compared with results obtained by a regional climate model of the Greenland system and ice sheet altimeter data obtained from NASA’s ICEsat mission. Our GRACE-only results differ to within 15% from these independently calculated values; we will comment on the possible causes and the quality of the glacial isostatic adjustment model which is used to correct geodetic datasets.","temporal gravity; greenland ice sheet; satellite gravimetry","en","journal article","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:5152aa83-ede5-4694-8345-8d8fc48f6061","http://resolver.tudelft.nl/uuid:5152aa83-ede5-4694-8345-8d8fc48f6061","Windmilling of turbofan engine; calculation of performance characteristics of a turbofan engine under windmilling","Ramanathan, A.","","2014","The turbofan is a type of air breathing jet engine that finds wide use in aircraft propulsion. During the normal operation of a turbofan engine installed in aircraft, the combustor is supplied with fuel, flow to the combustor is cut off and the engine runs under so called Windmilling conditions being driven only by the ram pressure ratio by producing drag. In-depth analysis is done to study the performance characteristics at this state.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f4451499-f096-4878-b28e-b62a8be6399b","http://resolver.tudelft.nl/uuid:f4451499-f096-4878-b28e-b62a8be6399b","Sheer driving pleasure; internship at the BMW Group in Munich, Germany","Hoogreef, M.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9419d436-d02b-470a-a3fd-09908e7e141c","http://resolver.tudelft.nl/uuid:9419d436-d02b-470a-a3fd-09908e7e141c","Applications of a discrete viscous adjoint method for aerodynamic shape optimisation of 3D configurations","Brezillon, J.; Dwight, R.P.","","2012","Within the next few years, numerical shape optimisation based on high-fidelity methods is likely to play a strategic role in future aircraft design. In this context, suitable tools have to be developed for solving aerodynamic shape optimisation problems, and the adjoint approach—which allows fast and accurate evaluations of the gradients with respect to the design parameters—is proved to be very efficient to eliminate the shock on aircraft wing in transonic flow. However, few applications were presented so far considering other design problems involving 3D viscous flows. This paper describes how the adjoint approach can also help the designer to efficiently reduce the flow separation onset at wing–fuselage intersection and to optimise the slat and flap positions of a 3D high-lift configuration. On all these cases, the optimisations were successfully performed within a limited number of flow evaluations, emphasising the benefit of the adjoint approach in aircraft shape design.","optimisation; adjoint method; aerodynamics; wing design; high lift","en","journal article","Springer-Verlag","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:443149ca-2cc7-45e0-b822-70853e687b8e","http://resolver.tudelft.nl/uuid:443149ca-2cc7-45e0-b822-70853e687b8e","Flight performance and propulsion; the introduction of a new master track","Voskuijl, M.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:926233cb-d999-41f5-86a6-4ce19965dce5","http://resolver.tudelft.nl/uuid:926233cb-d999-41f5-86a6-4ce19965dce5","Differential constraints for bounded recursive identification with multivariate splines","De Visser, C.C.; Chu, Q.P.; Mulder, J.A.","","2011","The ability to perform online model identification for nonlinear systems with unknown dynamics is essential to any adaptive model-based control system. In this paper, a new differential equality constrained recursive least squares estimator for multivariate simplex splines is presented that is able to perform online model identification and bounded model extrapolation in the framework of a model-based control system. A new type of linear constraints, the differential constraints, are used as differential boundary conditions within the recursive estimator which limit polynomial divergence when extrapolating data. The differential constraints are derived with a new, one-step matrix form of the de Casteljau algorithm, which reduces their formulation into a single matrix multiplication. The recursive estimator is demonstrated on a bivariate dataset, where it is shown to provide a speedup of two orders of magnitude over an ordinary least squares batch method. Additionally, it is demonstrated that inclusion of differential constraints in the least squares optimization scheme can prevent polynomial divergence close to edges of the model domain where local data coverage may be insufficient, a situation often encountered with global recursive data approximation.","multivariate splines; parameter estimation; scattered data; function approximators","en","journal article","Elsevier","","","","","","","2014-05-01","Aerospace Engineering","Control & Operations","","","",""
"uuid:bfec103e-7ecf-482a-9e0c-aee4a03d18a2","http://resolver.tudelft.nl/uuid:bfec103e-7ecf-482a-9e0c-aee4a03d18a2","Planetary Radio Interferometry and Doppler Experiment (PRIDE) for Planetary Atmospheric Studies","Bocanegra Bahamon, T.M.; Cimo, G.; Duev, D.; Gurvits, L.; Molera Calves, G.; Pogrebenko, S.","","2015","","","en","journal article","European Geosciences Union (EGU)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:88e166c8-d1c6-4c1e-b5a4-3932b55fe13d","http://resolver.tudelft.nl/uuid:88e166c8-d1c6-4c1e-b5a4-3932b55fe13d","Aiming at a 1-cm orbit for low earth orbiters: Reduced-dynamic and kinematic precise orbit determination","Visser, P.N.A.M.; Van den IJssel, J.","","2003","The computation of high-accuracy orbits is a prerequisite for the success of Low Earth Orbiter (LEO) missions such as CHAMP, GRACE and GOCE. The mission objectives of these satellites cannot be reached without computing orbits with an accuracy at the few cm level. Such a level of accuracy might be achieved with the techniques of reduced-dynamic and kinematic precise orbit determination (POD) assuming continuous Satellite-to-Satellite Tracking (SST) by the Global Positioning System CGPS). Both techniques have reached a high level of maturity and have been successfully applied to missions in the past, for example to TOPEX/POSEIDON (TIP), leading to Csub-)decimeter orbit accuracy. New LEO gravity missions are (to be) equipped with advanced GPS receivers promising to provide very high quality SST observations thereby opening the possibility for computing cm-level accuracy orbits. The computation of orbits at this accuracy level does not only require high-quality GPS receivers, but also advanced and demanding observation preprocessing and correction algorithms. Moreover, sophisticated parameter estimation schemes need to be adapted and extended to allow the computation of such orbits. Finally, reliable methods need to be employed for assessing the orbit quality and providing feedback to the ditferent processing steps in the orbit computation process.","precise orbit determination; reduced-dynamic; kinematic; GPS; LEO","en","journal article","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:d44782dc-28a5-4038-ae73-c7117ceae5e8","http://resolver.tudelft.nl/uuid:d44782dc-28a5-4038-ae73-c7117ceae5e8","Development of Design Rules for Adhesive Bonded Joints","Van Straalen, I.J.; Van Tooren, M.J.L.","","2002","This article deals with the development of design rules for structural adhesive bonded joints. In daily practice engineers are confronted with the problem to verify the reliability of their designs. This can be done with use of an experimental programme, but for the marine, transport, building and civil engineering sectors this will not be an option, because it is too expensive and time consuming. The use of design rules might be an alternative, but current guidelines for structural adhesive bonded joints do not guarantee the reliability. To develop design rules that meet the required level of reliability, new approaches have to be used. Such a systematic approach is presented in this article. It is based on the current structural adhesive bonding technology and on structural reliability methods. Partial factors are used to take the required reliability level into account. Additional conversion factors are introduced to cover the effects of ageing. Methods are discussed how to calibrate these factors. To illustrate the developed approach, examples of calibrating design rules for metal overlap joints with epoxy and polyurethane adhesives are presented","","en","journal article","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2f36e570-3a42-475b-b80f-b6a285e51295","http://resolver.tudelft.nl/uuid:2f36e570-3a42-475b-b80f-b6a285e51295","Reduced thermal conductivity by nanoscale intergrowths in perovskite like layered structure La2Ti2O","Khaliq, J.; Li, C.; Chen, K.; Shi, B.; Ye, H.; Grande, A.M.; Yan, H.; Reece, M.J.","","2015","The effect of substitution and oxidation-reduction on the thermal conductivity of perovskite-like layered structure (PLS) ceramics was investigated in relation to mass contrast and non-stoichiometry. Sr (acceptor) was substituted on the A site, while Ta (donor) was substituted on the B site of La2Ti2O7. Substitution in PLS materials creates atomic scale disorders to accommodate the non-stoichiometry. High resolution transmission electron microscopy and X ray diffraction revealed that acceptor substitution in La2Ti2O7 produced nanoscale intergrowths of n?=?5 layered phase, while donor substitution produced nanoscale intergrowths of n?=?3 layered phase. As a result of these nanoscale intergrowths, the thermal conductivity value reduced by as much as ?20%. Pure La2Ti2O7 has a thermal conductivity value of ?1.3?W/m K which dropped to a value of ?1.12?W/m K for Sr doped La2Ti2O7 and ?0.93?W/m K for Ta doped La2Ti2O7 at 573?K.","","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:6d7eacdf-219e-44f1-b65b-31ad9a64f48d","http://resolver.tudelft.nl/uuid:6d7eacdf-219e-44f1-b65b-31ad9a64f48d","Sea?level fingerprint of continental water and ice mass change from GRACE","Riva, R.E.M.; Bamber, J.L.; Lavallée, D.A.; Wouters, B.","","2010","The Gravity Recovery and Climate Experiment satellites (GRACE) provide, for the first time, a method to directly measure mass exchange between the land and oceans over time. The dominant components of this exchange are due to continental ice loss/gain and land hydrology. Here, we determine the secular trend in these two components during the GRACE measurement era: 2003–2009. For each component, we model the distinct regional signatures or fingerprints of relative sea?level (RSL) change, obtaining maxima at low latitudes between ±40° N/S, but with particularly strong regional patterns. We estimate that the total ice and water mass loss from the continents is causing global mean sea?level to rise by 1.0 ± 0.4 mm/yr. Isolating the ice and hydrological signals, we find that the former is the sole net contributor to the global mean, while the latter dominates regional RSL changes in many coastal areas.","sea-level change; fingerprints; GRACE","en","journal article","American Geophysical Union","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:5c81b6eb-7a7d-4a27-85b3-0eb2ccff732d","http://resolver.tudelft.nl/uuid:5c81b6eb-7a7d-4a27-85b3-0eb2ccff732d","Spy in a backpack","Van Dijk, T.","","2012","It must be able to fly in a swarm at great speeds, but also land on a ledge to survey the surroundings for hours at a time. The Atmov is the latest gadget from TU Delft’s MAV-lab.","Atmov","en","journal article","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:94bd42d1-4071-4d13-b278-1766553898f7","http://resolver.tudelft.nl/uuid:94bd42d1-4071-4d13-b278-1766553898f7","On top of the world; internship at Esrange Space Center","Olthof, H.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8f825342-0860-4316-a3d1-66b375cce610","http://resolver.tudelft.nl/uuid:8f825342-0860-4316-a3d1-66b375cce610","Modeling Human Multimodal Perception and Control Using Genetic Maximum Likelihood Estimation","Zaal, P.M.T.; Pool, D.M.; Chu, Q.P.; Van Paassen, M.M.; Mulder, M.; Mulder, J.A.","","2009","This paper presents a new method for estimating the parameters of multi-channel pilot models that is based on maximum likelihood estimation. To cope with the inherent nonlinearity of this optimization problem, the gradient-based Gauss-Newton algorithm commonly used to optimize the likelihood function in terms of output error is complemented with a genetic algorithm. This significantly increases the probability of finding the global optimum of the optimization problem. The genetic maximum likelihood method is successfully applied to data from a recent human-in-the-loop experiment. Accurate estimates of the pilot model parameters and the remnant characteristics were obtained. Multiple simulations with increasing levels of pilot remnant were performed, using the set of parameters found from the experimental data, to investigate how the accuracy of the parameter estimate is affected by increasing remnant. It is shown that only for very high levels of pilot remnant the bias in the parameter estimates is substantial. Some adjustments to the maximum likelihood method are proposed to reduce this bias.","System Identification; Pilot Modeling; Parameter Estimation","en","journal article","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:32910655-4a6d-451f-80cc-6caead06cecb","http://resolver.tudelft.nl/uuid:32910655-4a6d-451f-80cc-6caead06cecb","Morphologic and Aerodynamic Considerations Regarding the Plumed Seeds of Tragopogon pratensis and Their Implications for Seed Dispersal","Casseau, V.; De Croon, G.C.H.E.; Izzo, D.; Pandolfi, C.","","2015","Tragopogon pratensis is a small herbaceous plant that uses wind as the dispersal vector for its seeds. The seeds are attached to parachutes that increase the aerodynamic drag force and increase the total distance travelled. Our hypothesis is that evolution has carefully tuned the air permeability of the seeds to operate in the most convenient fluid dynamic regime. To achieve final permeability, the primary and secondary fibres of the pappus have evolved with complex weaving; this maximises the drag force (i.e., the drag coefficient), and the pappus operates in an “optimal” state. We used computational fluid dynamics (CFD) simulations to compute the seed drag coefficient and compare it with data obtained from drop experiments. The permeability of the parachute was estimated from microscope images. Our simulations reveal three flow regimes in which the parachute can operate according to its permeability. These flow regimes impact the stability of the parachute and its drag coefficient. From the permeability measurements and drop experiments, we show how the seeds operate very close to the optimal case. The porosity of the textile appears to be an appropriate solution to achieve a lightweight structure that allows a low terminal velocity, a stable flight and a very efficient parachute for the velocity at which it operates.","","en","journal article","Public Library of Science","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:69a92955-68cc-4140-b487-d79ee10c6ece","http://resolver.tudelft.nl/uuid:69a92955-68cc-4140-b487-d79ee10c6ece","Building satellites; an interview with Joost Elstak","Van Ettinger, A.; Dekker, S.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0a02e03b-572a-44b5-b105-8ca673a775dd","http://resolver.tudelft.nl/uuid:0a02e03b-572a-44b5-b105-8ca673a775dd","Main results of the third international PIV Challenge","Stanislas, M.; Okamoto, K.; Kähler, C.J.; Westerweel, J.; Scarano, F.","","2008","This paper presents the main results of the third international PIV Challenge which took place in Pasadena (USA) on the 19th and 20th of September 2005. This workshop was linked to the PIV05 International Symposium held at the same place the same week. The present contribution states the objectives of the challenge, describes the test cases and the algorithms used by the participants, and presents the main results together with some discussion and conclusions on the accuracy and robustness of various PIV and PTV algorithms. As the entire amount of results obtained cannot be detailed, this contribution is written as a guide for the use of the full database of images and results which is available at http://www.pivChallenge.org.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c38b6812-a2fe-4b61-8e7f-c910dfd42e72","http://resolver.tudelft.nl/uuid:c38b6812-a2fe-4b61-8e7f-c910dfd42e72","Interior design and accessibility aspects of the Superbus","Terzi, A.; Van Deelen, J.; Ockels, W.J.","","2007","The Superbus (Fig.1) is a new public transport vehicle designed for comfortable, flexible and sustainable transportation. The Superbus, which drives at 250 km/h cruising speed on its dedicated infrastructures (the supertrack) and at conventional speed on existing roads, is safe, sustainable, and able to transport passengers and goods from point to point. In this paper the philosophy of the vehicle will be highlighted in terms of the vehicle fundamental concepts. Then, the analysis of the required personal space design will be discussed alongside the design criteria for accessibility. Finally, the layout of the vehicle will be described in its details.","Superbus","en","journal article","SAE International","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:9067ebef-d37d-4a26-a5e7-62c9e61acdf7","http://resolver.tudelft.nl/uuid:9067ebef-d37d-4a26-a5e7-62c9e61acdf7","To Mars and beyond; interview with Dr. Firouz Naderi, the director solar system exploration at NASA JPL","Fattahyani, A.","","2013","NASA’s Jet Propulsion Laboratory (JPL) is the leader of the planetary missions. Located in Pasadena, California, this laboratory is responsible for the operation of NASA’s planetary spacecraft and its deep space network. The Leonardo Times was able to have an interview with Dr. Firouz Naderi, who is the director of the solar system exploration program at JPL, to talk about the new exciting missions NASA has planned for future","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8bc7677f-d74a-4a7d-828d-262e62cbd21e","http://resolver.tudelft.nl/uuid:8bc7677f-d74a-4a7d-828d-262e62cbd21e","Eulerian and Lagrangian views of a turbulent boundary layer flow using time-resolved tomographic PIV","Schröder, A.; Geisler, R.; Staack, K.; Elsinga, G.E.; Scarano, F.; Wieneke, B.; Henning, A.; Poelma, C.; Westerweel, J.","","2010","Coherent structures and their time evolution in the logarithmic region of a turbulent boundary layer investigated by means of 3D space–time correlations and time-dependent conditional averaging techniques are the focuses of the present paper. Experiments have been performed in the water tunnel at TU Delft measuring the particle motion within a volume of a turbulent boundary layer flow along a flat plate at a free-stream velocity of 0.53 m/s at Re ? = 2,460 based on momentum thickness by using time-resolved tomographic particle image velocimetry (PIV) at 1 kHz sampling rate and particle tracking velocimetry (PTV). The obtained data enable an investigation into the flow structures in a 3D Eulerian reference frame within time durations corresponding to 28 ?/U. An analysis of the time evolution of conditional averages of vorticity components representing inclined hairpin-like legs and of Q2- and Q4-events has been performed, which gives evidence to rethink the early stages of the classical hairpin development model for high Reynolds number TBLs. Furthermore, a PTV algorithm has been applied on the time sequences of reconstructed 3D particle image distributions identifying thousands of particle trajectories that enable the calculation of probability distributions of the three components of Lagrangian accelerations.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:da77cd4c-6fe8-41cb-87c5-0e274401559d","http://resolver.tudelft.nl/uuid:da77cd4c-6fe8-41cb-87c5-0e274401559d","Unsteady flow organization of compressible planar base flows","Humble, R.A.; Scarano, F.; Van Oudheusden, B.W.","","2007","The unsteady flow features of a series of two-dimensional, planar base flows are examined, within a range of low-supersonic Mach numbers in order to gain a better understanding of the effects of compressibility on the organized global dynamics. Particle image velocimetry is used as the primary diagnostic tool in order to characterize the instantaneous near wake behavior, in combination with data processing using proper orthogonal decomposition. The results show that the mean flowfields are simplified representations of the instantaneous flow organizations. Generally, each test case can be characterized by a predominant global mode, which undergoes an evolution with compressibility, within the Mach number range considered. (The term “global mode” is defined herein as an organized global dynamical behavior of the near wake region, recognizing that the near wake dynamics may be describable in terms of several global modes.) At Mach 1.46, the predominant global mode can be characterized by a sinuous or flapping motion. With increasing compressibility, this flapping mode decreases, and the predominant global mode evolves into a pulsating motion aligned with the wake axis at Mach 2.27. These global modes play an important role in the distributed nature of the turbulence properties. The turbulent mixing processes become increasingly confined to a narrower redeveloping wake with increasing compressibility. Global maximum levels of the streamwise turbulence intensity and the kinematic Reynolds shear stress occur within the vicinity of the mean reattachment location, and show no systematic trend with compressibility. In contrast, the global maximum level of the vertical turbulence intensity moves upstream from the redeveloping wake toward the mean reattachment location. The vertical turbulence intensity decays thereafter more slowly than the other turbulence quantities. Overall, the local maximum levels of the turbulence properties decrease appreciably with increasing compressibility.","compressible flow; supersonic flow; flow visualisation; wakes; turbulence","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:bca3a8af-b094-4da9-8127-901c6c65d88f","http://resolver.tudelft.nl/uuid:bca3a8af-b094-4da9-8127-901c6c65d88f","Changing the game; innovation for design and manufacturing of reinforced rubber composites","Blomaard, S.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b42ff16b-530d-4e71-abfa-75f687ec59de","http://resolver.tudelft.nl/uuid:b42ff16b-530d-4e71-abfa-75f687ec59de","Composite blade damaging under impact","Menouillard, T.; Réthoré, J.; Bung, H.; Suffis, A.","","2006","Composites materials are now being used in primary aircraft structures, and other domains because of numerous advantages. A part of a continuous in-flight operating costs, gas turbine engine manufacturers are always looking for ways to decrease engine weight. This is the case of compressor blades which have to satisfy, for example, the standard bird strike or debris in order to measure the crashworthiness. Bird strike impacts are actually among the most challenging loads that composite blades must accommodate. Thus for the further development of composite structures, it becomes important to have available predictive tools for simulating the response of composite structures under crash or impact loads, which will allow to evaluate damage state in the structure in function of time. A composites damage model, without mesh dependency, is presented, and allows to obtain agreement with impact experiment. Examples of finite element simulations for the impact response of blade based on this materials model are developped. These numerical results correspond to a bird strike on an equivalent composites blade, and insists on damage evolution in structure.","","en","journal article","EDP sciences","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b80dfdd2-1fe6-49ec-bb40-d402f5577c09","http://resolver.tudelft.nl/uuid:b80dfdd2-1fe6-49ec-bb40-d402f5577c09","Efficient computation of steady water flow with waves","Wackers, J.; Koren, J.","","2007","","steady water waves; turbulence; volume-of-fluid; compressive limiter; multigrid; defect correction","en","journal article","Wiley Interscience","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a8aa13d8-2813-46cb-94b9-29c76f979dc4","http://resolver.tudelft.nl/uuid:a8aa13d8-2813-46cb-94b9-29c76f979dc4","GOCE: The first seismometer in orbit around the Earth","Garcia, R.F.; Bruinsma, S.; Lognonné, P.; Doornbos, E.N.; Cachoux, F.","","2013","The first in situ sounding of a post-seismic infrasound wavefront is presented, using data from the GOCE mission. The atmospheric infrasounds following the great Tohoku earthquake (on 11 March 2011) induce variations of air density and vertical acceleration of the GOCE platform. These signals are detected at two positions along the GOCE orbit corresponding to a crossing and a doubling of the infrasonic wavefront created by seismic surface waves. Perturbations up to 11% of air density and 1.35?×?10???7?m/s2 of vertical acceleration are observed and modeled with two different solid-atmosphere coupling codes. These perturbations are a due to acoustic waves creating vertical velocities up to 130 m/s. Amplitudes and arrival times of these perturbations are reproduced respectively within a factor 2, and within a 60?s time window. Waveforms present a good agreement with observed data. The vertical acceleration to air density perturbation ratio is higher for these acoustic waves than for gravity waves. Combining these two pieces of information offers a new way to distinguish between these two wave types. This new type of data is a benchmark for the models of solid-atmosphere coupling. Amplitude and frequency content constrain the infrasound attenuation related to atmosphere viscosity and thermal conductivity. Observed time shifts between data and synthetics are ascribed to lateral variations of the seismic and atmospheric sound velocities and to the influence of atmospheric winds. These effects should be included in future modeling. This validation of our modeling tools allows to specify more precisely future observation projects.","post-seismic infrasounds; GOCE; Tohoku earthquake; atmospheric seismometer; thermosphere; seismic waves","en","journal article","American Geophysical Union","","","","","","","2013-09-14","Aerospace Engineering","Space Engineering","","","",""
"uuid:9f445eb9-0272-4ef8-9d82-661eae0166e2","http://resolver.tudelft.nl/uuid:9f445eb9-0272-4ef8-9d82-661eae0166e2","Novabike: Racing towards the future ; proving the capabilities of sustainable transport","Cavens, W.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:048955b2-b433-49a6-982f-b1749d5216dc","http://resolver.tudelft.nl/uuid:048955b2-b433-49a6-982f-b1749d5216dc","Supersonic flow research; getting a doctorate degree in the United States of America","Baars, W.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7c3baa5d-e1d4-431d-adfd-fee5a519680b","http://resolver.tudelft.nl/uuid:7c3baa5d-e1d4-431d-adfd-fee5a519680b","Identifying water mass depletion in northern Iraq observed by GRACE","Mulder, G.; Olsthoorn, T.N.; Al-manmi, D.A.M.A.; Schrama, E.J.O.; Smidt, E.H.","","2015","Observations acquired by Gravity Recovery And Climate Experiment (GRACE) mission indicate a mass loss of 146 ± 6 mm equivalent water height (EWH) in northern Iraq between 2007 and 2009. These data are used as an independent validation of lake mass variations and a rainfall-runoff model, which is based on local geology and climate conditions. Model inputs are precipitation from Tropical Rainfall Measurement Mission (TRMM) observations, and climatic parameters from Global Land Data Assimilation Systems (GLDAS) model parameters. The model is calibrated with observed river discharge and includes a representation of the karstified aquifers in the region to improve model realism. Lake mass variations were derived from Moderate Resolution Imaging Spectroradiometer (MODIS) in combination with satellite altimetry and some in situ data. Our rainfall-runoff model confirms that northern Iraq suffered a drought between 2007 and 2009 and captures the annual cycle and longer trend of the observed GRACE data. The total mass depletion seen by GRACE between 2007 and 2009 is mainly explained by a lake mass depletion of 75 ± 3 mm EWH and a natural groundwater depletion of 39 ± 8 mm EWH. Our findings indicate that anthropogenic groundwater extraction has a minor influence in this region, while a decline in lake mass and natural depletion of groundwater play a key role.","OA-Fund TU Delft","en","journal article","European Geosciences Union (EGU)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:86428cba-60e4-464a-baa2-77600aca0a4c","http://resolver.tudelft.nl/uuid:86428cba-60e4-464a-baa2-77600aca0a4c","Noise in multivariate GPS position time-series","Amiri-Simkooei, A.R.","","2008","A methodology is developed to analyze a multivariate linear model, which occurs in many geodetic and geophysical applications. Proper analysis of multivariate GPS coordinate time-series is considered to be an application. General, special, and more practical stochastic models are adopted to assess the noise characteristics of multivariate time-series. The least-squares variance component estimation (LS-VCE) is applied to estimate full covariance matrices among different series. For the special model, it is shown that the multivariate time-series can be estimated separately, and that the (cross) correlation between series propagates directly into the correlation between the corresponding parameters in the functional model. The time-series of five permanent GPS stations are used to show how the correlation between series propagates into the site velocities. The results subsequently conclude that the general model is close to the more practical model, for which an iterative algorithm is presented. The results also indicate that the correlation between series of different coordinate components per station is not significant. However, the spatial correlation between different stations for individual components is significant (a correlation of 0.9 over short baselines) both for white and for colored noise components.","Least-squares variance component estimation (LS-VCE); Normal distribution; Multivariate GPS time-series; Spatial correlation","en","journal article","Springer","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:1a702117-6668-4560-a80a-d2113905a6c5","http://resolver.tudelft.nl/uuid:1a702117-6668-4560-a80a-d2113905a6c5","A sparse collocation method for solving time-dependent HJB equations using multivariate B-splines","Govindarajan, N.; De Visser, C.C.; Krishnakumar, K.","","2014","This paper presents a sparse collocation method for solving the time-dependent Hamilton–Jacobi–Bellman (HJB) equation associated with the continuous-time optimal control problem on a fixed, finite timehorizon with integral cost functional. Through casting the problem in a recursive framework using the value iteration procedure, the value functions of every iteration step is approximated with a time-varying multivariate simplex B-spline on a certain state domain of interest. In the collocation scheme, the timedependent coefficients of the spline function are further approximated with ordinary univariate B-splines to yield a discretization for the value function fully in terms of piece-wise polynomials. The B-spline coefficients are determined by solving a sequence of highly sparse quadratic programming problems. The proposed algorithm is demonstrated on a pair of benchmark example problems. Simulation results indicate that the method can yield increasingly more accurate approximations of the value function by refinement of the triangulation.","optimal control; Hamilton-Jacobi-Bellman equation; multivariate splines; collocation method; adaptive dynamic programming","en","journal article","Elsevier / International Federation of Automatic Control (IFAC)","","","","","","","2014-12-20","Aerospace Engineering","Control & Operations","","","",""
"uuid:65304890-5799-4154-b4f0-221e6b646c47","http://resolver.tudelft.nl/uuid:65304890-5799-4154-b4f0-221e6b646c47","A surrogate based multistage-multilevel optimization procedure for multidisciplinary design optimization","Yao, W.; Chen, X.; Ouyang, Q.; Van Tooren, M.","","2011","Optimization procedure is one of the key techniques to address the computational and organizational complexities of multidisciplinary design optimization (MDO). Motivated by the idea of synthetically exploiting the advantage of multiple existing optimization procedures and meanwhile complying with the general process of satellite system design optimization in conceptual design phase, a multistage-multilevel MDO procedure is proposed in this paper by integrating multiple-discipline-feasible (MDF) and concurrent subspace optimization (CSSO), termed as MDFCSSO. In the first stage, the approximation surrogates of high-fidelity disciplinary models are built by disciplinary specialists independently, based on which the single level optimization procedure MDF is used to quickly identify the promising region and roughly locate the optimum of the MDO problem. In the second stage, the disciplinary specialists are employed to further investigate and improve the baseline design obtained in the first stage with highfidelity disciplinary models. CSSO is used to organize the concurrent disciplinary optimization and system coordination so as to allow disciplinary autonomy. To enhance the reliability and robustness of the design under uncertainties, the probabilistic version of MDF-CSSO (PMDF-CSSO) is developed to solve uncertainty-based optimization problems. The effectiveness of the proposed methods is verified with one MDO benchmark test and one practical satellite conceptual design optimization problem, followed by conclusion remarks and future research prospects.","multidisciplinary design optimization (MDO); optimization procedure; multiple-discipline-feasible (MDF); concurrent subspace optimization (CSSO); surrogate model","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Structures and Design Methodolody","","","",""
"uuid:77bb6130-81fe-41a6-bf1b-d32436f98ebc","http://resolver.tudelft.nl/uuid:77bb6130-81fe-41a6-bf1b-d32436f98ebc","From science fiction to reality; the Delft Robotics Team introduces personal robot 'Robby'","Küpers, B.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:528eb89a-0438-4b95-811a-9b2489b344de","http://resolver.tudelft.nl/uuid:528eb89a-0438-4b95-811a-9b2489b344de","A multi-temporal InSAR method incorporating both persistent scatterer and small baseline approaches","Hooper, A.","","2008","Synthetic aperture radar (SAR) interferometry is a technique that provides high-resolution measurements of the ground displacement associated with many geophysical processes. Advanced techniques involving the simultaneous processing of multiple SAR acquisitions in time increase the number of locations where a deformation signal can be extracted and reduce associated error. Currently there are two broad categories of algorithms for processing multiple acquisitions, persistent scatterer and small baseline methods, which are optimized for different models of scattering. However, the scattering characteristics of real terrains usually lay between these two end-member models. I present here a new method that combines both approaches, to extract the deformation signal at more points and with higher overall signal-to-noise ratio than can either approach alone. I apply the combined method to data acquired over Eyjafjallajökull volcano in Iceland, and detect time-varying ground displacements associated with two intrusion events.","MT-UnSAR; PSI; SBAS","en","journal article","American Geophysical Union","","","","","","","","Aerospace Engineering","Delft Institute for Earth Observation and Space Systems","","","",""
"uuid:8ea3efd8-4a2b-4003-b5aa-962afd2dc27f","http://resolver.tudelft.nl/uuid:8ea3efd8-4a2b-4003-b5aa-962afd2dc27f","Delta Lloyd solar boat team; sailing 30km/h with a solar-powered boat, using hydrofoils","Tra, M.","","2013","Every two years since 2006, the Delta Lloyd Solar Boat Team builds a boat to participate in the World Cup for solar-powered boats, across the ‘Elfsteden-route’, the famous tour of the eleven cities in the Dutch province of Friesland. The upcoming year the team, consisting of a new group of students, will start designing and building the 2014 Solar Boat.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d422f351-bf1b-41c3-a2dd-0e4cc60e937c","http://resolver.tudelft.nl/uuid:d422f351-bf1b-41c3-a2dd-0e4cc60e937c","Self-healing thermal barrier coatings; with application to gas turbine engines","Ponnusami, S.A.","","2013","Thermal Barrier Coating (TBC) systems have been applied in turbine engines for aerospace and power plants since the beginning of the 1980s to increase the energy efficiency of the engine, by allowing for higher operation temperatures. TBC systems on average need to be replaced about four times during the lifetime of an aircraft. Hence, life extension of such systems are always desirable in order to minimise costintensive maintenance operations. This research focuses on developing self-healing TBC systems to enhance their lifetime.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:48d5caaf-c577-45aa-9588-46f173905daf","http://resolver.tudelft.nl/uuid:48d5caaf-c577-45aa-9588-46f173905daf","Facilitaire inkoop: De toegevoegde waarde van zij-instromers","Reunis, M.R.B.","","2007","","","nl","journal article","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8f6dfa30-e8bb-46a1-ac00-72be27222f7f","http://resolver.tudelft.nl/uuid:8f6dfa30-e8bb-46a1-ac00-72be27222f7f","GPS position time-series analysis based on asymptotic normality of M-estimation","Khodabandeh, A.; Amiri-Simkooei, A.R.; Sharifi, M.A.","","2011","The efficacy of robust M-estimators is a well-known issue when dealing with observational blunders. When the number of observations is considerably large—long time series for instance—one can take advantage of the asymptotic normality of the M-estimation and compute reasonable estimates for the unknown parameters of interest. A few leading M-estimators have been employed to identify the most likely functional model for GPS coordinate time series. This includes the simultaneous detection of periodic patterns and offsets in the GPS time series. Estimates of white noise, flicker noise, and random walk noise components are also achieved using the robust M-estimators of (co)variance components, developed in the framework of the least-squares variance component estimation (LS-VCE) theory. The method allows one to compute confidence interval for the (co)variance components in asymptotic sense. Simulated time series using white noise plus flicker noise show that the estimates of random walk noise fluctuate more than those of flicker noise for different M-estimators. This is because random walk noise is not an appropriate noise structure for the series. The same phenomenon is observed using the results of real GPS time series, which implies that the combination of white plus flicker noise is well described for GPS time series. Some of the estimated noise components of LS-VCE differ significantly from those of other M- estimators. This reveals that there are a large number of outliers in the series. This conclusion is also affirmed by performing the statistical tests, which detect (large) parts of the outliers but can also leave parts to be undetected.","M-estimation; least squares variance component estimation (LS-VCE); robust variance component estimation; GPS coordinate time series; asymptotic normality","en","journal article","Springer","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:382a490a-7926-48ac-b176-dee1ad477ce0","http://resolver.tudelft.nl/uuid:382a490a-7926-48ac-b176-dee1ad477ce0","Exploring undulating fin propulsion; towards a bio-inspired, multifunctional underwater sensing platform","Henrion, S.; Vercruyssen, T.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:384cb76a-d53f-4048-8f7b-af1b161a64e9","http://resolver.tudelft.nl/uuid:384cb76a-d53f-4048-8f7b-af1b161a64e9","Long-term passive distance-bounded relative motion in the presence of TeX perturbations","Chu, J.; Guo, J.; Gill, E.K.A.","","2015","This paper presents closed-form solutions for the problem of long-term satellite relative motion in the presence of J2 perturbations, and introduces a design methodology for long-term passive distance-bounded relative motion. There are two key ingredients of closed-form solutions.One is the model of relative motion; the other is the Hamiltonian model and its canonical solution of the J2 -perturbed absolute motion. The model of relative motion makes no assumptions on the eccentricity of the reference orbit or on the magnitude of the relative distances. Besides, the relative motion model is concise with straightforward physical insight, and consistent with the Hamiltonian model. The Hamiltonian model takes into account the secular, long-periodic and short-periodic effects of the J2 perturbation. It also remains separable in terms of spherical coordinates to ensure the application of the Hamilton–Jacobi theory to derive the canonical solution. When deriving the canonical solution, pseudo-circular and pseudo-elliptical orbits are treated separately and Carlson’s method is employed to calculate elliptic integrals, which takes advantage of the symmetry of the integrand. These symmetry properties hold physical insights of the J2 -perturbed absolute motion. To design the long-term distance-bounded relative motion, the nodal period and the drift of right ascension of the ascending node (RAAN) per nodal period are, respectively, matched non-instantaneously. Even though the nodal period and the drift of RAAN per nodal period can be obtained via the canonical solution, action-angle variables are used to obtain the frequency of the system without finding the complete solution to the perturbed orbital motion.","distributed space systems; distance-bounded relative motion; Hamiltonian dynamics; action-angle variables; J2; J 2 perturbation; J 2 -invariant orbits","en","journal article","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:ca33dce4-4759-47d0-9cb6-0ada96770e9e","http://resolver.tudelft.nl/uuid:ca33dce4-4759-47d0-9cb6-0ada96770e9e","A passion for sustainablility; an interview with Joris Melkert","Wamiti, L.; Komogorova, J.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7af9715e-28d7-4a36-82bd-4904dd216562","http://resolver.tudelft.nl/uuid:7af9715e-28d7-4a36-82bd-4904dd216562","Study tour 'Limitless'; study tour through the U.S.A. and Canada","Van Gorcum, J.","","2013","“What was the best part of the tour?” A question often asked, both during and after the Study Tour 2013 ‘Limitless’, which took thirty students and four sta! members on an amazing trip through 2 countries, 8 cities and 12 #ights. The question proved very di""cult to answer, the most common answer was simply “Everything”.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3b39889d-9800-4198-b15c-7685dd63db9e","http://resolver.tudelft.nl/uuid:3b39889d-9800-4198-b15c-7685dd63db9e","Optimal topology of future composites; a new optimisation approach for future composite materials","Peeters, D.","","2014","Weight reduction has been a driving factor in aerospace engineering for a long time. Recently, the first composite-dominated airplanes (e.g., A-380, B-787) have been taken into use. Composites have replaced aluminium because of their higher strength-to-weight and stiffness-to-weight ratio. Currently, research is ongoing on variable stiffness composites which have the promise to further reduce the weight of composites.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:51494cf7-5d36-4fdb-8770-daa14a498553","http://resolver.tudelft.nl/uuid:51494cf7-5d36-4fdb-8770-daa14a498553","Experimental investigation of liquid jet injection into Mach 6 hypersonic crossflow","Beloki Perurena, J.; Asma, C.O.; Theunissen, R.; Chazot, O.","","2008","The injection of a liquid jet into a crossing Mach 6 air flow is investigated. Experiments were conducted on a sharp leading edge flat plate with flush mounted injectors. Water jets were introduced through different nozzle shapes at relevant jet-to-air momentum-flux ratios. Sufficient temporal resolution to capture small scale effects was obtained by high-speed recording, while directional illumination allowed variation in field of view. Shock pattern and flow topology were visualized by Schlieren-technique. Correlations are proposed on relating water jet penetration height and lateral extension with the injection ratio and orifice diameter for circular injector jets. Penetration height and lateral extension are compared for different injector shapes at relevant jet-to-air momentum-flux ratios showing that penetration height and lateral extension decrease and increase, respectively, with injector's aspect ratio. Probability density function analysis has shown that the mixing of the jet with the crossflow is completed at a distance of x/d (j) similar to 40, independent of the momentum-flux ratio. Mean velocity profiles related with the liquid jet have been extracted by means of an ensemble correlation PIV algorithm. Finally, frequency analyses of the jet breakup and fluctuating shock pattern are performed using a Fast Fourier algorithm and characteristic Strouhal numbers of St = 0.18 for the liquid jet breakup and of St = 0.011 for the separation shock fluctuation are obtained","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:478d168e-3df6-45f8-b0c8-fe26255c76d2","http://resolver.tudelft.nl/uuid:478d168e-3df6-45f8-b0c8-fe26255c76d2","MAVLAB; competing with Micro Air Vehicles (MAV)","Smeur, E.; Tijmons, S.","","2013","The IMAV is an annual international conference and competition involving Micro Air Vehicles (MAVs). In September, the 2013 edition was held in Toulouse, France. The MAVLab from the faculty of Aerospace Engineering, TU Delft joined the competition with a group of thirteen students (MSc/PhD) and sta! members. The goal was not only to win the competition, but also to highlight recent developments and demonstrate capabilities of our group.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a15688da-c4d6-4445-9fd9-56fabd61e549","http://resolver.tudelft.nl/uuid:a15688da-c4d6-4445-9fd9-56fabd61e549","Internship at Bentley Motors; driving luxury performance","Minde, F.","","2014","Bentleys are amongst the most sought after luxury cars of the world. They are known for their performance on the road, the luxury in the cabin, their reliability and the artisanship involved in making every single one of them. It was an honor to be part of the Quality Department of a company with such a rich history in British car manufacturing as part of my six-month internship.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:693c8434-c69a-42b7-b70a-79de8c6adb33","http://resolver.tudelft.nl/uuid:693c8434-c69a-42b7-b70a-79de8c6adb33","Power from the skies: Laddermill takes airborne wind energy to new heights","De Wachter, A.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:85efb4b3-ac5d-422c-876b-7abafccc643c","http://resolver.tudelft.nl/uuid:85efb4b3-ac5d-422c-876b-7abafccc643c","Designing aircraft in Italy; internship at Piaggio Aero Industries","Coosemans, J.","","2013","From October 2012 to January 2013, I went to the south of Italy to do my internship at Piaggio, the company famous for manufacturing the P.180 Avanti business aircraft. The office where I was located was in Pozzuoli, a town just outside the city of Naples, in the shadow of Mount Vesuvius.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d6ffb141-c13b-4750-93ab-f16e69ecf243","http://resolver.tudelft.nl/uuid:d6ffb141-c13b-4750-93ab-f16e69ecf243","Digital radiographic technology; non-destructive testing of tubine blades","Penumadu, P.S.","","2014","Inspection of turbine blades has always been a big challenge. Any irregularities in the blade have a huge impact on the gas turbine, so these blades have to be manufactured and inspected in the most sophisticated way possible. The evolution of digital radiographic technology took a leap forward to solve these problems in the industry environment which also enhances production quality and reduce rework.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c89f9e7d-ea2d-4ce6-b74c-1faabad284c2","http://resolver.tudelft.nl/uuid:c89f9e7d-ea2d-4ce6-b74c-1faabad284c2","Microblock rotations and fault coupling in SE Asia triple junction (Sulawesi, Indonesia) from GPS and earthquake slip vector data","Socquet, A.; Simons, W.J.F.; Vigny, C.; McCaffrey, R.; Subarya, C.; Sarsito, D.; Ambrosius, B.; Spakman, W.","","2006","The island of Sulawesi, eastern Indonesia, is located within the triple junction of the Australian, Philippine, and Sunda plates and accommodates the convergence of continental fragments with the Sunda margin. We quantify the kinematics of Sulawesi by modeling GPS velocities and earthquake slip vectors as a combination of rigid block rotations and elastic deformation around faults. We find that the deformation can be reasonably described by a small number of rapidly rotating crustal blocks. Relative to the Sunda Plate, the southwestern part of Sulawesi (Makassar Block) rotates anticlockwise at ?1.4°/Myr. The northeastern part of Sulawesi, the Bangai?Sula domain, comprises three blocks: the central North Sula Block moves toward the NNW and rotates clockwise at ?2.5°/Myr, the northeastern Manado Block rotates clockwise at ?3°/Myr about a nearby axis, and East Sulawesi is pinched between the North Sula and Makassar blocks. Along the boundary between the Makassar Block and the Sunda Plate, GPS measurements suggest that the trench accommodates ?15 mm/yr of slip within the Makassar Strait with current elastic strain accumulation. The tectonic boundary between North Sula and Manado blocks is the Gorontalo Fault, moving right laterally at about 11 mm/yr and accumulating elastic strain. The 42 mm/yr relative motion between North Sula and Makassar blocks is accommodated on the Palu?Koro left?lateral strike?slip fault zone. The data also indicate a pull?apart structure in Palu area, where the fault shows a transtensive motion and may have a complex geometry involving several active strands. Sulawesi provides a primary example of how collision can be accommodated by crustal block rotation instead of mountain building.","interseismic coupling; SE Asia; kinematics; GPS; elastic model","en","journal article","American Geophysical Union","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:43eb305b-0cfc-4536-9559-6b8920233952","http://resolver.tudelft.nl/uuid:43eb305b-0cfc-4536-9559-6b8920233952","A discrete dislocation transformation model for austenitic single crystals","Shi, J.; Turteltaub, S.; Van der Giessen, E.; Remmers, J.J.C.","","2008","","","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3ce0fe53-c60d-4632-b0f2-9b94762a6214","http://resolver.tudelft.nl/uuid:3ce0fe53-c60d-4632-b0f2-9b94762a6214","A new generation of composite laminates; patented fibre architecture improves damage tolerance","Nagelsmit, M.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:74ce7ded-be55-4950-a4fa-739249395a40","http://resolver.tudelft.nl/uuid:74ce7ded-be55-4950-a4fa-739249395a40","Delfi-N3XT; final design and production","Bouwmeester, J.","","2011","Delfi-n3Xt, the second university satellite of TU Delft, is scheduled for launch in the last quarter of 2012. The development team is currently active in finalizing the design and building an engineering model which should be finished by the end of 2011. In this article the latest design is presented to provide insight on this exciting mission","Delfi-n3Xt","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4df97103-beb4-43c5-87f7-917cf9538d6a","http://resolver.tudelft.nl/uuid:4df97103-beb4-43c5-87f7-917cf9538d6a","The space elevator and its future; travelling to space without a rocket","Stevens, C.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:66d2502a-988a-44e7-880a-47926386dae9","http://resolver.tudelft.nl/uuid:66d2502a-988a-44e7-880a-47926386dae9","Ariane 6: ESA at a crossroads","Gerth, I.","","2013","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:02c0327d-da82-42d9-88ae-d44a0106fe66","http://resolver.tudelft.nl/uuid:02c0327d-da82-42d9-88ae-d44a0106fe66","Spectral expressions for modelling the gravitational field of the Earth’s crust density structure","Tenzer, R.; Novak, P.; Vajda, P.","","2011","We derive expressions for computing the gravitational field (potential and its radial derivative) generated by an arbitrary homogeneous or laterally varying density contrast layer with a variable depth and thickness based on methods for a spherical harmonic analysis and synthesis of gravity field. The newly derived expressions are utilised in the gravimetric forward modelling of major known density structures within the Earth’s crust (excluding the ocean density contrast) beneath the geoid surface. The gravitational field quantities due to the sediments and crust components density contrasts, shown in numerical examples, are computed using the 2 × 2 arc-deg discrete data from the global crustal model CRUST2.0. These density contrasts are defined relative to the adopted value of the reference crustal density of 2670 kgm?3. All computations are realised globally on a 1 × 1 arc-deg geographical grid at the Earth’s surface. The maxima of the gravitational signal due to the sediments density contrast are mainly along continental shelf regions with the largest sedimentary deposits. The corresponding maxima due to the consolidated crust components density contrast are over areas of the largest continental crustal thickness with variable geological structure.","density; Earths crust; forward modelling; gravity; spherical harmonics","en","journal article","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:a312b059-56c3-4cfb-9c46-01c6b7c03fe0","http://resolver.tudelft.nl/uuid:a312b059-56c3-4cfb-9c46-01c6b7c03fe0","State of the art and prospectives of smart rotor control for wind turbines","Barlas, T.K.; Van Kuik, G.A.M.","","2007","","","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c7b9e4b4-053b-44ee-8861-0d9decc1e6ea","http://resolver.tudelft.nl/uuid:c7b9e4b4-053b-44ee-8861-0d9decc1e6ea","Student life in Colorado; where spaceflight and snowboarding meet","Herman, J.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:93d077bb-d61f-4bfe-9273-9d4c9b7f0fbf","http://resolver.tudelft.nl/uuid:93d077bb-d61f-4bfe-9273-9d4c9b7f0fbf","Detectability of groundwater storage change within the Great Lakes Water Basin using GRACE","Huang, J.; Halpenny, J.; Van der Wal, W.; Klatt, C.; James, T.S.; Rivera, A.","","2012","Groundwater is a primary hydrological reservoir of the Great Lakes Water Basin (GLB), which is an important region to both Canada and US in terms of culture, society and economy. Due to insufficient observations, there is a knowledge gap about groundwater storage variation and its interaction with the Great Lakes. The objective of this study is to examine the detectability of the groundwater storage change within the GLB using the monthly models from the Gravity Recovery And Climate Experiment (GRACE) satellite mission, auxiliary soil moisture, snow and lake (SMSL) data, and predictions from glacial isostatic adjustment (GIA) models. A two-step filtering method is developed to optimize the extraction of GRACE signal. A two dimensional basin window weight function is also introduced to reduce ringing artifacts caused by the band-limited GRACE models in estimating the water storage change within the GLB. The groundwater storage (GWS) as deviation from a reference mean storage is estimated for the period of 2002 to 2009. The average GWS of the GLB clearly show an annual cycle with an amplitude range from 27 to 91 mm in water thickness equivalent (WTE), and a phase range of about two months. The estimated phases of GWS variations have a half year shift with respect to the phase of SMSL water storage variations which show peaks in March and April. The least squares estimation gives a GWS loss trend of from 2.3 to 9.3 km3/yr within the GLB for the period of study. This wide range of the GRACE GWS results is caused largely by the differences of soil moisture and snow storage from different land surface models (LSMs), and to a lesser extent by the GRACE commission and omission errors, and the GIA model error.","GRACE; groundwater; satellite gravity","en","journal article","American Geophysical Union","","","","","","","2013-02-01","Aerospace Engineering","Space Engineering","","","",""
"uuid:44330aea-77b9-46ad-b2ab-09452b766420","http://resolver.tudelft.nl/uuid:44330aea-77b9-46ad-b2ab-09452b766420","Artificial Force Field for Haptic Feedback in UAV Teleoperation","Lam, T.M.; Boschloo, H.W.; Mulder, M.; Van Paassen, M.M.","","2009","The feedback upon which operators in teleoperation tasks base their control actions differs substantially from the feedback to the driver of a vehicle. On the one hand, there is often a lack of sensory information; on the other hand, there is additional status information presented via the visual channel. Haptic feedback could be used to unload the visual channel and to compensate for the lack of feedback in other modalities. For collision avoidance, haptic feedback could provide repulsive forces via the control inceptor. Haptic feedback allows operators to interpret the repulsive forces as impedance to their control deflections when a potential for collision exists. Haptic information can be generated from an artificial force field (AFF) that maps environment constraints to repulsive forces. This paper describes the design and theoretical evaluation of a novel AFF, i.e., the parametric risk field, for teleoperation of an uninhabited aerial vehicle (UAV). The field allows adjustments of the size, shape, and force gradient by means of parameter settings, which determine the sensitivity of the field. Computer simulations were conducted to evaluate the effectiveness of the field for collision avoidance for various parameter settings. Results indicate that the novel AFF more effectively performs the collision avoidance function than potential fields known from literature. Because of its smaller size, the field yields lower repulsive forces, results in less force cancellation effects, and allows for larger UAV velocities. This indicates less operator control demand and more effective UAV operations, both expected to lead to lower operator workload, while, at the same time, increasing safety.","artificial force field (AFF); collision avoidance; haptic feedback; teleoperation; uninhabited aerial vehicle (UAV)","en","journal article","IEEE","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:9002ee5f-7f40-46a3-b51d-8ad2d6f6391e","http://resolver.tudelft.nl/uuid:9002ee5f-7f40-46a3-b51d-8ad2d6f6391e","Measuring in a wall of air","Wassink, J.","Scarano, F. (contributor); Schrijer, F. (contributor)","2008","","visualising fast airflows","en","journal article","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9218b117-bb2e-4495-9b72-d13e7b0f3948","http://resolver.tudelft.nl/uuid:9218b117-bb2e-4495-9b72-d13e7b0f3948","Role of Tie Points in Integrated Sensor Orientation for Photogrammetric Map Compilation","Khoshelham, K.","","2009","Direct measurement of exterior orientation parameters has been a challenge in photogrammetry for many years. Direct sensor orientation using a calibrated GPS/INS system can potentially eliminate the need for ground control points and aerial tiiangulation, and consequently, result in a great reduction in the cost and time of aerial photogrammetry. Previous studies have shown that, compared to conventional aerial tiiangulation, direct sensor orientation yields larger errors in the image and object space. It has also been shown that including a number of tie points within an integrated orientation approach can result in a reduction of errors in the image space. In this paper, the influence of the number and distribution of tie points on integrated orientation is investigated. Experiments with various numbers of tie points regularly as well as randomly distributed are presented. Results indicate that an increase in the number of tie points up to one point per model results in a considerable reduc¬tion of the errors in the image space.","OA-Fund TU Delft","en","journal article","American Society for Photogrammetry and Remote Sensing","","","","","","","","Aerospace Engineering","Optical and Laser Remote Sensins Section, Earth Observation and Space Systems","","","",""
"uuid:95f181e2-6a51-4801-90e8-7985a9c1a250","http://resolver.tudelft.nl/uuid:95f181e2-6a51-4801-90e8-7985a9c1a250","Three-dimensional vortex organization in a high-Reynolds-number supersonic turbulent boundary layer","Elsinga, G.E.; Adrian, R.J.; Van Oudheusden, B.W.; Scarano, F.","","2010","Tomographic particle image velocimetry was used to quantitatively visualize the three-dimensional coherent structures in a supersonic (Mach 2) turbulent boundary layer in the region between y/? = 0.15 and 0.89. The Reynolds number based on momentum thickness Re? = 34000. The instantaneous velocity fields give evidence of hairpin vortices aligned in the streamwise direction forming very long zones of low-speed fluid, consistent with Tomkins & Adrian (J. Fluid Mech., vol. 490, 2003, p. 37). The observed hairpin structure is also a statistically relevant structure as is shown by the conditional average flow field associated to spanwise swirling motion. Spatial low-pass filtering of the velocity field reveals streamwise vortices and signatures of large-scale hairpins (height > 0.5?), which are weaker than the smaller scale hairpins in the unfiltered velocity field. The large-scale hairpin structures in the instantaneous velocity fields are observed to be aligned in the streamwise direction and spanwise organized along diagonal lines. Additionally the autocorrelation function of the wall-normal swirling motion representing the large-scale hairpin structure returns positive correlation peaks in the streamwise direction (at 1.5? distance from the DC peak) and along the 45° diagonals, which also suggest a periodic arrangement in those directions. This is evidence for the existence of a spanwise–streamwise organization of the coherent structures in a fully turbulent boundary layer.","","en","journal article","Cambridge University Press","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:99baef20-b792-4801-910e-a50bfae7c243","http://resolver.tudelft.nl/uuid:99baef20-b792-4801-910e-a50bfae7c243","Internship in Brisbane, Australia; subtropical composite structures","Hooning, S.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:79a31333-da66-4ada-ad40-d6713ae3fe17","http://resolver.tudelft.nl/uuid:79a31333-da66-4ada-ad40-d6713ae3fe17","VLBI observations of the radio quasar J2228+0110 at z=5.95 and other field sources in multiple-phase-centre mode","Cao, H.M.; Frey, S.; Gurvits, L.; Yang, J.; Hong, X.Y.; Paragi, Z.; Deller, A.T.; Ivezic, Z.","","2014","A patch of sky in the SDSS Stripe 82 was observed at 1.6 GHz with Very Long Baseline Interferometry (VLBI) using the European VLBI Network (EVN). The data were correlated at the EVN software correlator at JIVE (SFXC). There are fifteen known mJy/sub-mJy radio sources in the target field defined by the primary beam size of a typical 30-m class EVN radio telescope. The source of particular interest is a recently identified high-redshift radio quasar: J222843.54+011032.2 (J2228+0110) at redshift z = 5.95. Our aim was to investigate the milli-arcsecond (mas) scale properties of all the VLBI-detectable sources within this primary beam area with a diameter of 20?. The source J2228+0110 was detected with VLBI with a brightness temperature Tb > 108 K, supporting the active galactic nucleus (AGN) origin of its radio emission, which is conclusive evidence that the source is a radio quasar. In addition, two other target sources were also detected, one of them with no redshift information. Their brightness temperature values (Tb > 107 K) measured with VLBI suggest a non-thermal synchrotron radiation origin for their radio emission. The detection rate of 20% is broadly consistent with other wide-field VLBI experiments carried out recently. We also derived the accurate equatorial coordinates of the three detected sources using the phase-referencing technique. This experiment is an early attempt of a wide-field science project with SFXC, paving the way for the EVN to conduct a large-scale VLBI survey in the multiple-phase-centre mode.","techniques: interferometric; radio continuum: galaxies; galaxies: active","en","journal article","EDP Sciences","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:4967c9ab-1efe-4e0d-ae2b-147a8715b81f","http://resolver.tudelft.nl/uuid:4967c9ab-1efe-4e0d-ae2b-147a8715b81f","India and Sunda plates motion and deformation along their boundary in Myanmar determined by GPS","Socquet, A.; Vigny, C.; Chamot-Rooke, N.; Simons, W.J.F.; Rangin, C.; Ambrosius, B.","","2006","Using a regional GPS data set including ?190 stations in Asia, from Nepal to eastern Indonesia and spanning 11 years, we update the present?day relative motion between the Indian and Sundaland plates and discuss the deformation taking place between them in Myanmar. Revisiting measurements acquired on the Main Boundary Thrust in Nepal, it appears that points in southern Nepal exhibit negligible deformation with respect to mainland India. Including these points, using a longer time span than previous studies, and making an accurate geodetic mapping in the newest reference frame allows us to refine the present?day Indian motion. Our results confirm that the current motion of India is slower than predicted by the NUVEL?1A model, and in addition our India?Eurasia motion is significantly (?5 mm/yr) slower than previous geodetic determinations. This new Indian motion, combined with a refined determination of the Sundaland motion, gives way to a relative India?Sunda angular velocity of 20.2°N, 26.1°E, 0.370°/Myr in ITRF2000, predicting a relative motion of 35 mm/yr oriented N10° at the latitude of Myanmar. There, the Sagaing Fault accommodates only 18 mm/yr of right?lateral strike slip, only half of the shear component of motion. We present two models addressing how and where the remaining deformation may occur. A first model of distributed deformation implies convergence on the Arakan subduction (the northern continuation of the now famous Sumatra?Andaman Trench) and wrench faulting in the Arakan wedge. The second model uses localized deformation, where deformation observed west of the Sagaing Fault is entirely due to elastic loading on a faster and oblique Arakan subduction (23 mm/yr). This latter model predicts that a major earthquake of Mw 8.5 may occur every century on this segment of the subduction.","GPS Myanmar; India kinematics; interseismic deformation","en","journal article","American Geophysical Union","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:cd18627e-b06a-4a10-ba19-fbdc972508ec","http://resolver.tudelft.nl/uuid:cd18627e-b06a-4a10-ba19-fbdc972508ec","Formation flying; an interview with Tobias Gutleb","Gutleb, T.; Perenboom, T.","","2011","One of last year's Desig Synthesis Exercise (DSE) groups dived into the concept of fuel saving by letting aircraft flying in formation. They took their project even a step further and applied for the National Aviation Prize, a contest which encourages innovation in aerospace applications. The prize was taken to Delft, and the reason why is explained by team member Tobias Gutleb","formation flying; fuel saving; National Aviation Prize","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1adf369c-d599-4a84-b3bf-0afaeaf064dd","http://resolver.tudelft.nl/uuid:1adf369c-d599-4a84-b3bf-0afaeaf064dd","Delfi-C3 to Delfi-N3XT: A breakdown; the building blocks developed and applied in five years of Delfi programme","Tindemans, A.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:992c7025-3eee-4654-a4e1-f2c4ffefccf0","http://resolver.tudelft.nl/uuid:992c7025-3eee-4654-a4e1-f2c4ffefccf0","Numerical modelling of transformation-induced damage and plasticity in metals","Suiker, A.S.J.; Turteltaub, S.","","2007","","","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ac54f9b0-1b30-40c2-9b2b-214f32fe8a2f","http://resolver.tudelft.nl/uuid:ac54f9b0-1b30-40c2-9b2b-214f32fe8a2f","Numerical simulation of the LAGEOS thermal behavior and thermal accelerations","Andrés, J.I.; Noomen, R.; Vecellio None, S.","","2006","The temperature distribution throughout the LAGEOS satellites is simulated numerically with the objective to determine the resulting thermal force. The different elements and materials comprising the spacecraft, with their energy transfer, have been modeled with unprecedented detail. The radiation inputs on the satellites are direct solar (eclipse modulated), Earth albedo, and Earth infrared radiations. For each satellite the lifetime temperature (behavior) of 2133 nodes is computed. On the basis of this distribution, individual forces and the net instantaneous accelerations are obtained. Simulations yield typical temperature variations ranging between 30 and 100 K for different elements and materials, whereas the net instantaneous accelerations are on the order of 70 pm s?2, in good agreement with previous results. Simulations also show the importance of the consideration of a proper orientation of the satellite: LOSSAM yields acceleration differences of up to three times the acceleration obtained with a constant spin axis orientation. The temperature of the four germanium retroreflectors deviates up to 70 and 100 K with respect to their silica counterparts for LAGEOS I and II, respectively. This generates thermal acceleration differences of several pm s?2, up to 25% of the postulated difference in reflectivity between hemispheres. Two factors play a major role: the spin rate and the Sun aspect angle with respect to the spin axis. On the basis of the latter, two characteristic periods can be distinguished: a rapid spin, slow drift period (until 13 and 8 years after launch for LAGEOS I and II, respectively) and a slow spin, rapid wobbling afterward. The acceleration results will be used in a refined orbit computation in a subsequent investigation.","LAGEOS; thermal behavior; empirical surface forces","en","journal article","American Geophysical Union","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:e54419c6-f294-4f02-97df-15b7b5c9f207","http://resolver.tudelft.nl/uuid:e54419c6-f294-4f02-97df-15b7b5c9f207","Evaluation of a LIDAR Land-Based Mobile Mapping System for Monitoring Sandy Coasts","Bitenc, M.; Lindenbergh, R.C.; Khoshelham, K.; Van Waarden, A.P.","","2011","The Dutch coast is characterized by sandy beaches flanked by dunes. Understanding the morphology of the coast is essential for defense against flooding of the hinterland. Because most dramatic changes of the beach and the first dune row happen during storms, it is important to assess the state of the coast immediately after a storm. This is expensive and difficult to organize with Airborne Laser Scanning (ALS). Therefore, the performance of a Land-based Mobile Mapping System (LMMS) in mapping a stretch of sandy Dutch coast of 6 km near the municipality of Egmond is evaluated in this research. A test data set was obtained by provider Geomaat using the StreetMapper LMMS system. Both the relative quality of laser point heights and of a derived Digital Terrain model (DTM) are assessed. First, the height precision of laser points is assessed a priori by random error propagation, and a posteriori by calculating the height differences between close-by points. In the a priori case, the result is a theoretical laser point precision of around 5 cm. In the a posteriori approach it is shown that on a flat beach a relative precision of 3 mm is achieved, and that almost no internal biases exist. In the second analysis, a DTM with a grid size of 1 m is obtained using moving least squares. Each grid point height includes a quality description, which incorporates both measurement precision and terrain roughness. Although some problems remain with the scanning height of 2 m, which causes shadow-effect behind low dunes, it is concluded that a laser LMMS enables the acquisition of a high quality DTM product, which is available within two days.","OA-Fund TU Delft; coast; hazards; laser scanning; DEM/DTM","en","journal article","MDPI","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:ef4fbaf8-b4c2-4898-bb1a-195120a07c23","http://resolver.tudelft.nl/uuid:ef4fbaf8-b4c2-4898-bb1a-195120a07c23","Giri, carico e uno scarico carbonio! Light weight composite exhaust design for Ferrari sports cars","Wagtho, L.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:628fb5ef-79b9-460b-9728-aab7f600571e","http://resolver.tudelft.nl/uuid:628fb5ef-79b9-460b-9728-aab7f600571e","Modelling situation awareness relations in a multiagent system","Blom, H.A.P.; Sharpanskykh, A.","","2015","There is broad consensus that situation awareness (SA) plays a key role in agent-based modelling of complex sociotechnical systems. However in the social sciences and human factors literature there are different views on what SA is and how it could be modelled. More specifically, one school of research considers SA as the process of gaining awareness, another school refers to it as to the product of gaining awareness, whereas the third school sees SA as a combination of the process and product. Typically, agent-based modelling of SA is done from the second view for each individual agent, possibly with additional social components to enable interaction. Current developments in multiagent systems indicate that social abilities and relations between agents should be not an addition, but at the core of any model of a sociotechnical system. To address this issue, we develop a mathematical modelling framework of SA relations between agents which supports all three views. The use of the framework is demonstrated by an example of retrospective accident modelling from the aviation domain.","situation awareness; multiagent systems; sociotechnical systems; formal framework","en","journal article","Springer","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:cb10205a-a3e1-4599-a4d6-c81d1e9e7f7e","http://resolver.tudelft.nl/uuid:cb10205a-a3e1-4599-a4d6-c81d1e9e7f7e","Predicting Spatial Variability of Sediment Properties From Hydrographic Data for Geoacoustic Inversion","Siemes, K.; Snellen, M.; Amiri-Simkooei, A.R.; Simons, D.G.; Hermand, J.P.","","2010","","environmental characterization; multibeam echosounder (MBES); sea bottom sediments; seismic profile; single-beam echosounder (SBES)","en","journal article","IEEE","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:12b905c7-2b50-4f4a-af68-7241cc70731f","http://resolver.tudelft.nl/uuid:12b905c7-2b50-4f4a-af68-7241cc70731f","Fast error analysis of continuous GPS observations","Bos, M.S.; Fernandes, R.M.S.; Williams, S.D.P.; Bastos, L.","","2007","It has been generally accepted that the noise in continuous GPS observations can be well described by a power-law plus white noise model. Using maximum likelihood estimation (MLE) the numerical values of the noise model can be estimated. Current methods require calculating the data covariance matrix and inverting it, which is a significant computational burden. Analysing 10 years of daily GPS solutions of a single station can take around 2 h on a regular computer such as a PC with an AMD AthlonTM 64 X2 dual core processor. When one analyses large networks with hundreds of stations or when one analyses hourly instead of daily solutions, the long computation times becomes a problem. In case the signal only contains power-law noise, the MLE computations can be simplified to a process where N is the number of observations. For the general case of power-law plus white noise, we present a modification of the MLE equations that allows us to reduce the number of computations within the algorithm from a cubic to a quadratic function of the number of observations when there are no data gaps. For time-series of three and eight years, this means in practise a reduction factor of around 35 and 84 in computation time without loss of accuracy. In addition, this modification removes the implicit assumption that there is no environment noise before the first observation. Finally, we present an analytical expression for the uncertainty of the estimated trend if the data only contains power-law noise.","GPS; Power-law; Correlated noise; Time-series analysis","en","journal article","Springer","","","","","","","","Aerospace Engineering","Delft Institute of Earth Observation and Space Systems","","","",""
"uuid:9e491852-ca64-4e6c-ade9-4c24e5011d3f","http://resolver.tudelft.nl/uuid:9e491852-ca64-4e6c-ade9-4c24e5011d3f","Laser beam welding of an Oxide Dispersion Strengthened super alloy","Lemmen, H.J.K.; Sudmeijer, K.J.; Richardson, I.M.; Van Der Zwaag, S.","","2007","","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c1c67faf-3e13-4ce9-b16c-ac60cfafb625","http://resolver.tudelft.nl/uuid:c1c67faf-3e13-4ce9-b16c-ac60cfafb625","Performances of motion tracking enhanced Tomo-PIV on turbulent shear flows","Novara, M.; Scarano, F.","","2012","The motion tracking enhancement technique (MTE) is a recently introduced method to improve the accuracy of tomographic PIV measurements at seeding density higher than currently practiced. The working principle is based on the fact that the particle field and its projections are correlated between the two exposures. Therefore, information from subsequent exposures can be shared within the tomographic reconstruction process of a single object, which largely reduces the energy lost into ghost particles. The study follows a previous work based on synthetic particle images, showing that the MTE technique has an effect similar to that of increasing the number of cameras. In the present analysis, MTE is applied to Tomographic PIV data from two time-resolved experiments on turbulent shear flows: a round jet at Re = 5,000 (f acq = 1,000 Hz) and a turbulent boundary layer at the trailing edge of an airfoil (Re c = 370,000) measured at 12,000 Hz. The application of MTE is extended to the case of more than two recordings. The performance is assessed comparing the results from a lowered number of cameras with respect to the full tomographic imaging system. The analysis of the jet flow agrees with the findings of numerical simulations provided the results are scaled taking into account the concept of MTE efficiency based on the volume fraction where ghost-pairs (Elsinga et al. 2010a) are produced. When a large fraction of fluid has uniform motion (stagnant fluid surrounding the jet), only a moderate reduction in ghost intensity is expected by MTE. Nevertheless, a visible recovery of reconstruction quality is observed for the 3-cameras system when MTE is applied making use of 3 recordings. In the turbulent boundary layer, the objective is set to increase the seeding density beyond current practice, and the experiments are performed at approximately 200,000 particles/megapixel. The measurement robustness is monitored with the signal-to-noise ratio S/N for the cross-correlation analysis. An estimate of the precision error is obtained for the turbulent boundary layer case following the peak height of the spatio-temporal cross-correlation function (frozen-turbulence). The MTE approach appears to be essential for the increase in robustness and measurement precision at such seeding density.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:00ebc051-925a-405c-aef5-216c3d79c912","http://resolver.tudelft.nl/uuid:00ebc051-925a-405c-aef5-216c3d79c912","Supersonic transport; aircraft that never flew","Adriaens, L.; Wormer, M.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:20294532-46ff-41d4-b90b-f96fc65d083a","http://resolver.tudelft.nl/uuid:20294532-46ff-41d4-b90b-f96fc65d083a","Behavior of the reflection function of a plane-parallel medium for directions of incidence and reflection tending to horizontal directions","Hovenier, J.W.; Stam, D.M.","","2008","The atmospheres of (exo) planets and moons, as well as reflection nebulae, contain in general independently scattering particles in random orientation and are often supposed to be plane-parallel. Relations are presented for the (bidirectional) reflection function and several related functions of such a medium in case the directions of incidence and reflection both tend to horizontal directions. The results are quite general. The medium may be semi-infinite or finite, with or without a reflecting surface underneath, and vertically homogeneous or inhomogeneous. Some approximative formulae for the reflection function of a plane-parallel medium with independently scattering particles in random orientation, including Lambert’s law, may be very inaccurate if the directions of incidence and reflection are both nearly horizontal.","","en","journal article","EDP sciences","","","","","","","","Aerospace Engineering","DEOS, Department of Aerospace Engineering","","","",""
"uuid:0468681f-099f-4f51-996b-13bddd1e6143","http://resolver.tudelft.nl/uuid:0468681f-099f-4f51-996b-13bddd1e6143","Early warbirds: The dawn of air combat","Van Dijk, E.","","2011","Aviation's first steps at the turn of the twentieth century and how the First World War accelerated warplane development","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0c002b3f-fc4e-4dcd-a0fb-792d41b46e43","http://resolver.tudelft.nl/uuid:0c002b3f-fc4e-4dcd-a0fb-792d41b46e43","Post-buckled precompressed elements: A new class of control actuators for morphing wing UAVs","Vos, R.; Barrett, R.; De Breuker, R.; Tiso, P.","","2007","","","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:72ed93c0-d13e-427c-8c5f-f013b737750e","http://resolver.tudelft.nl/uuid:72ed93c0-d13e-427c-8c5f-f013b737750e","Accuracy of the International Terrestrial Reference Frame origin and Earth expansion","Wu, X.; Collilieux, X.; Altamimi, Z.; Vermeersen, L.L.A.; Gross, R.S.; Fukumori, I.","","2011","The International Terrestrial Reference Frame (ITRF) is a fundamental datum for high?precision orbit tracking, navigation, and global change monitoring. Accurately realizing and maintaining ITRF origin at the mean Earth system center of mass (CM) is critical to surface and spacecraft based geodetic measurements including those of sea level rise and its sources. Although ITRF combines data from satellite laser ranging (SLR), Very Long Baseline Interferometry (VLBI), Global Positioning System (GPS), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), its origin is currently realized by the single technique of SLR. Consequently, it is difficult to independently evaluate the origin accuracy. Also, whether the solid Earth is expanding or shrinking has attracted persistent attention. The expansion rate, if any, has not been accurately determined before, due to insufficient data coverage on the Earth's surface and the presence of other geophysical processes. Here, we use multiple precise geodetic data sets and a simultaneous global estimation platform to determine that the ITRF2008 origin is consistent with the mean CM at the level of 0.5 mm yr?1, and the mean radius of the Earth is not changing to within 1? measurement uncertainty of 0.2 mm yr?1.","geocenter motion; solid Earth expansion; terrestrial reference frames","en","journal article","American Geophysical Union","","","","","","","2012-01-08","Aerospace Engineering","Space Engineering","","","",""
"uuid:02ed62d8-83b3-4aaf-adb3-4c72ece4b5f5","http://resolver.tudelft.nl/uuid:02ed62d8-83b3-4aaf-adb3-4c72ece4b5f5","Multi-frame pyramid correlation for time-resolved PIV","Sciacchitano, A.; Scarano, F.; Wieneke, B.","","2012","A novel technique is introduced to increase the precision and robustness of time-resolved particle image velocimetry (TR-PIV) measurements. The innovative element of the technique is the linear combination of the correlation signal computed at different separation time intervals. The domain of the correlation signal resulting from different temporal separations is matched via homothetic transformation prior to the averaging of the correlation maps. The resulting ensemble-averaged correlation function features a significantly higher signal-to-noise ratio and a more precise velocity estimation due to the evaluation of a larger particle image displacement. The method relies on a local optimization of the observation time between snapshots taking into account the local out-ofplane motion, continuum deformation due to in-plane velocity gradient and acceleration errors. The performance of the pyramid correlation algorithm is assessed on a synthetically generated image sequence reproducing a three-dimensional Batchelor vortex; experiments conducted in air and water flows are used to assess the performance on time-resolved PIV image sequences. The numerical assessment demonstrates the effectiveness of the pyramid correlation technique in reducing both random and bias errors by a factor 3 and one order of magnitude, respectively. The experimental assessment yields a significant increase of signal strength indicating enhanced measurement robustness. Moreover, the amplitude of noisy fluctuations is considerably attenuated and higher precision is obtained for the evaluation of time-resolved velocity and acceleration.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:3d828e1d-59e3-44cc-8cd0-b29649ef8e6c","http://resolver.tudelft.nl/uuid:3d828e1d-59e3-44cc-8cd0-b29649ef8e6c","Generalized grain cluster method for multiscale response of multiphase materials","Yadegari, S.; Turteltaub, S.R.; Suiker, A.S.J.","","2015","A multiscale approach termed the generalized grain cluster method (GGCM) is presented, which can be applied for the prediction of the macroscopic behavior of an aggregate of single crystal grains composing a multiphase material. The GGCM is based on the minimization of a functional that depends on the microscopic deformation gradients in the grains through the equilibrium requirements of the grains as well as kinematic compatibility between grains. By means of the specification of weighting factors it is possible to mimic responses falling between the Taylor and Sachs bounds. The numerical solution is computed with an incremental-iterative algorithm based on a constrained gradient descent method. For a multiscale analysis, the GCCM can be included at integration points of a standard finite element code to simulate macroscopic problems. A comparison with FEM direct numerical simulations illustrates that the computational time of the GGCM may be up to about an order of magnitude lower.","multiscale method; homogenization; grain cluster; multiphase material; TRIP steel","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:75c067d3-ef95-4aab-a6b0-43ff5139b73d","http://resolver.tudelft.nl/uuid:75c067d3-ef95-4aab-a6b0-43ff5139b73d","Wavefront reconstruction in adaptive optics systems using nonlinear multivariate splines","De Visser, C.C.; Verhaegen, M.H.G.","","2012","This paper presents a new method for zonal wavefront reconstruction (WFR) with application to adaptive optics systems. This new method, indicated as Spline based ABerration REconstruction (SABRE), uses bivariate simplex B-spline basis functions to reconstruct the wavefront using local wavefront slope measurements. The SABRE enables WFR on nonrectangular and partly obscured sensor grids and is not subject to the waffle mode. The performance of SABRE is compared to that of the finite difference (FD) method in numerical experiments using data from a simulated Shack Hartmann lenslet array. The results show that SABRE offers superior reconstruction accuracy and noise rejection capabilities compared to the FD method.","","en","journal article","Optical Society of America","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:32e096d4-800a-4e17-8e0a-db6f00edfd6d","http://resolver.tudelft.nl/uuid:32e096d4-800a-4e17-8e0a-db6f00edfd6d","Experimentally observed effects of yaw misalignment on the inflow in the rotor plane","Haans, W.; Van Kuik, G.; Van Bussel, G.","","2007","","","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a7cdbc02-49cb-4d8c-a6d7-c4241abd3b14","http://resolver.tudelft.nl/uuid:a7cdbc02-49cb-4d8c-a6d7-c4241abd3b14","Robot ray the bloodhound; searching underwater for cyanobacteria, terrorists, and mines is all in a day’s work for a robot ray developed by a team of aerospace engineering students","Muller, M.","Simons, D. (contributor)","2009","","robot ray; underwater sensor platform","en","journal article","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a4248ce1-0378-4402-960f-0bd201012dd4","http://resolver.tudelft.nl/uuid:a4248ce1-0378-4402-960f-0bd201012dd4","Aerodynamic roughness length estimation from very high-resolution imaging LIDAR observations over the Heihe basin in China","Colin, J.; Faivre, R.","","2010","","","en","journal article","Copernicus, GmbH","","","","","","","","Aerospace Engineering","","","","",""
"uuid:05302a8b-8d78-4b07-bbbf-099cd1fe6f00","http://resolver.tudelft.nl/uuid:05302a8b-8d78-4b07-bbbf-099cd1fe6f00","The choice of the spherical radial basis functions in local gravity field modeling","Tenzer, R.; Klees, R.","","2008","The choice of the optimal spherical radial basis function (SRBF) in local gravity field modelling from terrestrial gravity data is investigated. Various types of SRBFs are considered: the point-mass kernel, radial multipoles, Poisson wavelets, and the Poisson kernel. The analytical expressions for the Poisson kernel, the point-mass kernel and the radial multipoles are well known, while for the Poisson wavelet new closed analytical expressions are derived for arbitrary orders using recursions. The performance of each SRBF in local gravity field modelling is analyzed using real data. A penalized least-squares technique is applied to estimate the gravity field parameters. As follows from the analysis, almost the same accuracy of gravity field modelling can be achieved for different types of the SRBFs, provided that the depth of the SRBFs is chosen properly. Generalized cross validation is shown to be a suitable technique for the choice of the depth. As a good alternative to generalized cross validation, we propose the minimization of the RMS differences between predicted and observed values at a set of control points. The optimal regularization parameter is determined using variance component estimation techniques. The relation between the depth and the correlation length of the SRBFs is established. It is shown that the optimal depth depends on the type of the SRBF. However, the gravity field solution does not change significantly if the depth is changed by several km. The size of the data area (which is always larger than the target area) depends on the type of the SRBF. The point-mass kernel requires the largest data area.","local gravity field modelling; penalized least-squares; spherical radial basis functions; variance component estimation; generalized cross validation","en","journal article","Springer","","","","","","","","Aerospace Engineering","Physical and Space Geodesy","","","",""
"uuid:9c9acd90-6f26-45e0-9fb6-bc7f2152fea9","http://resolver.tudelft.nl/uuid:9c9acd90-6f26-45e0-9fb6-bc7f2152fea9","Printing a revolution; a new world in aerospace manufacturing: Additive processes","Coosemans, J.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5574b422-2646-4c9f-9974-7b3228dc51cb","http://resolver.tudelft.nl/uuid:5574b422-2646-4c9f-9974-7b3228dc51cb","Helicopter industry - early beginnings to now; an outlook on the helicopter market and its major players in the rotorcraft industry","Spranger, L.","","2013","The helicopter is probably the most flexible aircraft that we know today. Although its history dates back to around 1500, the first practical helicopter wasn’t manufactured until the 1940s, roughly three decades after the Wright brothers’ first powered human flight. Today, helicopters fulfil a wide range of tasks both in the civil and in the military sectors. Rescue missions requiring high precision, surveillance or quick transport are all possible due to this wonder of vertical light.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e3f69728-519b-4075-b5e9-fff9750ac238","http://resolver.tudelft.nl/uuid:e3f69728-519b-4075-b5e9-fff9750ac238","Effect of polymer architecture on the intrinsic self-healing character of polymers","Garcia Espallargas, S.J.","","2014","Intrinsic and extrinsic self-healing strategies can be employed to mitigate the effects of local damage in order to (partially) restore a lost property or functionality and to avoid premature catastrophic failure of the whole system. It is well known that polymer architecture has a crucial influence on mechanical, physical and thermal properties. However, the effect of polymer architecture on the healing capabilities of self-healing polymers has not yet been studied in detail. This paper addresses the effect of polymer architecture on the intrinsic healing character of polymeric materials using different reversible chemistries and aims at highlighting the need for more studies on this particular topic.","self-healing; polymer architecture; reversible chemistry; intrinsic healing","en","journal article","Elsevier","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:b1ae5c0c-ac8c-4650-a53f-361887f8b31a","http://resolver.tudelft.nl/uuid:b1ae5c0c-ac8c-4650-a53f-361887f8b31a","Antarctic outlet glacier mass change resolved at basin scale from satellite gravity gradiometry","Bouman, J.; Fuchs, M.; Ivins, E.; Van der Wal, W.; Schrama, E.J.O.; Visser, P.N.A.M.; Horwath, M.","","2014","The orbit and instrumental measurement of the Gravity Field and Steady State Ocean Circulation Explorer (GOCE) satellite mission offer the highest ever resolution capabilities for mapping Earth's gravity field from space. However, past analysis predicted that GOCE would not detect changes in ice sheet mass. Here we demonstrate that GOCE gravity gradiometry observations can be combined with Gravity Recovery and Climate Experiment (GRACE) gravity data to estimate mass changes in the Amundsen Sea Sector. This refined resolution allows land ice changes within the Pine Island Glacier (PIG), Thwaites Glacier, and Getz Ice Shelf drainage systems to be measured at respectively ?67?±?7, ?63?±?12, and ?55?±?9 Gt/yr over the GOCE observing period of November 2009 to June 2012. This is the most accurate pure satellite gravimetry measurement to date of current mass loss from PIG, known as the “weak underbelly” of West Antarctica because of its retrograde bed slope and high potential for raising future sea level.","basin-scale ice mass change; Amundsen Sea Sector, Antarctica; satellite gravimetry","en","journal article","American Geophysical Union","","","","","","","2015-02-20","Aerospace Engineering","Space Engineering","","","",""
"uuid:3dcbe952-398e-4e00-a62f-eac443d9a247","http://resolver.tudelft.nl/uuid:3dcbe952-398e-4e00-a62f-eac443d9a247","Effect of air jet vortex generators on a shock wave boundary layer interaction","Souverein, L.J.; Debiève, J.F.","","2010","The effect of upstream injection by means of continuous air jet vortex generators (AJVGs) on a shock wave turbulent boundary layer interaction is experimentally investigated. The baseline interaction is of the impinging type, with a flow deflection angle of 9.5degrees and a Mach number Me = 2.3. Considered are the effects of the AJVGs on the upstream boundary layer flow topology and on the spatial and dynamical characteristics of the interaction. To this aim, Stereoscopic Particle Image Velocimetry has been employed, in addition to hot-wire anemometry (HWA) for the investigation of the unsteady characteristics of the reflected shock. The AJVGs cause a reduction of the separation bubble length and height. In addition, the energetic frequency range of the reflected shock is increased by approximately 50%, which is in qualitative agreement with the smaller separation bubble size.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9ef4db71-3856-4949-9337-f93ad08d37b0","http://resolver.tudelft.nl/uuid:9ef4db71-3856-4949-9337-f93ad08d37b0","Impact of Galileo on Global Ionosphere Map Estimation","","","2006","The upcoming GNSS Galileo, with its new satellite geometry and frequency plan, will not only bring many benefits for navigation and positioning but also help to improve ionosphere delay estimation. This paper investigates ionosphere estimation with Galileo and compares it with the results from GPS-only and combined GPS-Galileo. The standard deviation of the Vertical Total Electron Content (VTEC) at a certain location can improve significantly by 40 per cent. Various Galileo configurations are considered to assess the differences in frequency plan and signals to be used. The IGS network, which is involved in producing the current IGS Global Ionosphere Map (GIM) is used in the simulation for more realistic results. A more accurate GIM will in its turn improve navigation and positioning performance.","GPS; Galileo; Ionosphere; Design Computation","en","journal article","Cambridge University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2caeefbc-ab6a-44d6-888e-2e8b82a2ae8c","http://resolver.tudelft.nl/uuid:2caeefbc-ab6a-44d6-888e-2e8b82a2ae8c","Unified State Model theory and application in astrodynamics","Vittaldev, V.; Mooij, E.; Naeije, M.C.","","2012","The Unified State Model is a method for expressing orbits using a set of seven elements. The elements consist of a quaternion and three parameters based on the velocity hodograph. A complete derivation of the original model is given in addition to two proposed modifications. Both modifications reduce the number of state elements from seven to six by replacing the quaternion with either modified Rodrigues parameters or the Exponential Map. Numerical simulations comparing the original Unified StateModel, the Unified State Model with modified Rodrigues parameters, and the Unified State Model with Exponential Map, with the traditional Cartesian coordinates have been carried out. The Unified StateModel and its derivatives outperform the Cartesian coordinates for all orbit cases in terms of accuracy and computational speed, except for highly eccentric perturbed orbits. The performance of the Unified State Model is exceptionally better for the case of orbits with continuous lowthrust propulsion with CPU simulation time being an order of magnitude lower than for the simulation using Cartesian coordinates. This makes the Unified State Model an excellent state propagator for mission optimizations.","Unified State Model · quaternion · modified Rodrigues parameters · orbit propagation · exponential map · hodograph","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0c8a1afc-76dc-43df-91f6-65043f0edf67","http://resolver.tudelft.nl/uuid:0c8a1afc-76dc-43df-91f6-65043f0edf67","Improved GRACE regional mass balance estimates of the Greenland Ice Sheet cross-validated with the input-output method (discussion paper)","Xu, Z.; Schrama, E.J.O.; Van der Wal, W.; Van den Broeke, M.; Enderlin, E.M.","","2015","In this study, we use satellite gravimetry data from the Gravity Recovery and Climate Experiment (GRACE) to estimate regional mass changes of the Greenland ice sheet (GrIS) and neighbouring glaciated regions using a least-squares inversion approach. We also consider results from the input-output method (IOM) that quantifies the difference between mass input and output of the surface mass balance (SMB) components from the Regional Atmospheric Climate Model version 2 (RACMO2) and ice discharge (D) from 12 years of high-precision ice velocity and thickness surveys. We use a simulation model to quantify and correct for GRACE approximation errors in mass changes between different sub-regions of GrIS and investigate the reliability of pre-1990s ice discharge estimates based on modelled runoff. We find that the difference between IOM and our improved GRACE mass change estimates is reduced in terms of the long-term mass changes when using runoff-based discharge estimates in several sub-areas. In most regions our GRACE and IOM solutions are consistent with other studies, but differences remain in the northwestern GrIS. We verify the GRACE mass balance in that region by considering several different GIA models and mass change estimates derived from the Ice, Cloud and land Elevation satellite (ICEsat). We conclude that the remaining differences between GRACE and IOM are likely due to underestimated uncertainties in the IOM solutions.","OA-Fund TU Delft","en","journal article","European Geosciences Union (EGU)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:5f11d8f1-94d5-4229-a05c-4963306f3854","http://resolver.tudelft.nl/uuid:5f11d8f1-94d5-4229-a05c-4963306f3854","GPS-derived orbits for the GOCE satellite","Bock, H.; Jäggi, A.; Meyer, U.; Visser, P.N.A.M.; Van den IJssel, J.A.A.; Van Helleputte, T.; Heinze, M.; Hugentobler, U.","","2011","The first ESA (European Space Agency) Earth explorer core mission GOCE (Gravity field and steady-state Ocean Circulation Explorer) was launched on 17 March 2009 into a sun-synchronous dusk–dawn orbit with an exceptionally low initial altitude of about 280 km. The onboard 12-channel dual-frequency GPS (Global Positioning System) receiver delivers 1 Hz data, which provides the basis for precise orbit determination (POD) for such a very low orbiting satellite. As part of the European GOCE Gravity Consortium the Astronomical Institute of the University of Bern and the Department of Earth Observation and Space Systems are responsible for the orbit determination of the GOCE satellite within the GOCE High-level Processing Facility. Both quick-look (rapid) and very precise orbit solutions are produced with typical latencies of 1 day and 2 weeks, respectively. This article summarizes the special characteristics of the GOCE GPS data, presents POD results for about 2 months of data, and shows that both latency and accuracy requirements are met. Satellite Laser Ranging validation shows that an accuracy of 4 and 7 cm is achieved for the reduced-dynamic and kinematic Rapid Science Orbit solutions, respectively. The validation of the reduced-dynamic and kinematic Precise Science Orbit solutions is at a level of about 2 cm.","GOCE; GPS; precise orbit determination; SLR validation","en","journal article","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:12d4e036-03e4-4298-8986-e6603c204d98","http://resolver.tudelft.nl/uuid:12d4e036-03e4-4298-8986-e6603c204d98","Regional high-resolution spatiotemporal gravity modeling from GRACE data using spherical wavelets","Schmidt, M.; Han, S.C.; Kusche, J.; Sanchez, L.; Shum, C.K.","","2006","We determine a regional spatiotemporal gravity field over northern South America including the Amazon region using GRACE inter-satellite range-rate measurements by application of a wavelet-based multiresolution technique. A major advantage of this method is that we are able to represent the Amazon hydrological signals in form of time series of detail signals with level-dependent temporal resolution: the coarser structures generally require only ten days, whereas the medium and finer details are computable from one month of data. To this end, we employ the basic property of multiresolution representations, which is to split a signal into detail signals, each related to a specific resolution level and computable from data covering a specific part of the spectrum. Our results, which for the first time fully exploit the spatial and temporal resolutions of GRACE data in modeling Amazon hydrological fluxes, are in good agreement with hydrological models and GPS-derived height variations.","","en","journal article","American Geophysical Union","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:5a24676e-ef16-43c6-b8cf-a72bba08d269","http://resolver.tudelft.nl/uuid:5a24676e-ef16-43c6-b8cf-a72bba08d269","Design of a large inflatable kiteplane","Breukels, J.; Ockels, W.J.","","2007","This paper presents the various structural considerations in designing a large inflatable kiteplane. Material issues are addressed and a departure from conventional inflatable kites is suggested by using a single material instead of a structural foil and an internal gas barrier. Furthermore, rigging the kite using bridle lines is given attention. It is shown that the required internal pressure for a beam to keep it stiff is greatly influenced by the location of the bridle line. An optimum placement of the bridle line is found through analysis of the bending behavior of the beam in combination with a stress-based wrinkling criterion.","","en","journal article","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:96139b14-16f7-4c20-8577-482a7aba7a3c","http://resolver.tudelft.nl/uuid:96139b14-16f7-4c20-8577-482a7aba7a3c","Controlling of merging electric field and IMF magnitude on storm-time changes in thermospheric mass density","Zhou, Y.L.; Ma, S.Y.; Liu, R.S.; Luehr, H.; Doornbos, E.","","2013","The controls of merging electrical field, Em, and IMF (interplanetary magnetic field) magnitude, B, on the storm-time changes in upper thermospheric mass density are statistically investigated using GRACE accelerometer observations and the OMNI data of solar wind and IMF for 35 great storms during 2002–2006. It reveals the following: (1) The correlation coefficients between the air mass density changes and the parameters of Em and B are generally larger at lower latitudes than at higher latitudes, and larger in noon and midnight sectors than in dawn and dusk. (2) The most likely delay time (MLDT) of mass density changes in respect to Em is about 1.5 h (4.5 h) at high (low) latitudes, having no distinct local time dependence, while it is 6 h at middle latitudes in all the local time sectors except for noon, which is longer than at low latitudes. A similar fact of longer delay time at mid-latitude is also seen for B. The MLDTs for B at various latitudes are all local time dependent distinctly with shorter delay time in noon/midnight sector and larger in dawn/dusk. Despite of widely spread of the delay time, IMF B exhibits still larger correlation coefficients with mass density changes among the interplanetary parameters. (3) The linear control factor of B on the density changes increases for large B, in contrast to somewhat saturation trend for larger Em. (4) The influence of B and Em on the mass densities shows different behavior for different types of storms. The influence intensity of Em is much stronger for CIR-driven than for CME-driven storm, while it is not so distinct for B. On the local time asymmetry of the influence, both Em and B have largest influence at noon sector for CME-driven storms, while an obviously larger intensification of the influence is found in dawn/dusk sector during CIR storms, especially for parameter Em.","","en","journal article","European Geosciences Union (EGU)","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:1ed0252c-61c4-4c6c-9475-d98ffa9bb019","http://resolver.tudelft.nl/uuid:1ed0252c-61c4-4c6c-9475-d98ffa9bb019","Traffic monitoring using helicopters; a system for the acquisition and analysis of image sequences to model longitudinal driving behavior","Nejadasl, F.K.; Menenti, M.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d003dbc5-5175-423b-a9da-82f4d8629862","http://resolver.tudelft.nl/uuid:d003dbc5-5175-423b-a9da-82f4d8629862","Identifying water mass depletion in Northern Iraq observed by GRACE","Mulder, G.; Olsthoorn, T.N.; Al-manmi, D.A.M.A.; Schrama, E.J.O.; Smidt, E.H.","","2014","Observations acquired by Gravity Recovery And Climate Experiment (GRACE) mission indicate a mass loss of 31 ± 3 km3 or 130 ± 14 mm in Northern Iraq between 2007 and 2009. This data is used as an independent validation of a hydrologic model of the region including lake mass variations. We developed a rainfall–runoff model for five tributaries of the Tigris River, based on local geology and climate conditions. Model inputs are precipitation from Tropical Rainfall Measurement Mission (TRMM) observations, and potential evaporation from GLDAS model parameters. Our model includes a representation of the karstified aquifers that cause large natural groundwater variations in this region. Observed river discharges were used to calibrate our model. In order to get the total mass variations, we corrected for lake mass variations derived from Moderate Resolution Imaging Spectroradiometer (MODIS) in combination with satellite altimetry and some in-situ data. Our rainfall–runoff model confirms that Northern Iraq suffered a drought between 2007 and 2009 and is consistent with the mass loss observed by GRACE over that period. Also, GRACE observed the annual cycle predicted by the rainfall–runoff model. The total mass depletion seen by GRACE between 2007 and 2009 is mainly explained by a lake mass depletion of 74 ± 4 mm and a natural groundwater depletion of 37 ± 6 mm. Our findings indicate that man-made groundwater extraction has a minor influence in this region while depletion of lake mass and geology play a key role.","","en","journal article","European Geosciences Union (EGU)","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:e99cfcfb-b520-4bc4-a3d9-071472daee49","http://resolver.tudelft.nl/uuid:e99cfcfb-b520-4bc4-a3d9-071472daee49","Random Taylor hypothesis and the behavior of local and convective accelerations in isotropic turbulence","Tsinober, A.; Vedula, P.; Yeung, P.K.","","2001","The properties of acceleration fluctuations in isotropic turbulence are studied in direct numerical simulations (DNS) by decomposing the acceleration as the sum of local and convective contributions (aL = ?u/?t and aC = u??u), or alternatively as the sum of irrotational and solenoidal contributions [aI = ??(p/?) and aS = ??2u]. The main emphasis is on the nature of the mutual cancellation between aL and aC which must occur in order for the acceleration (a) to be small as predicted by the “random Taylor hypothesis” [Tennekes, J. Fluid Mech. 67, 561 (1975)] of small eddies in turbulent flow being passively “swept” past a stationary Eulerian observer. Results at Taylor-scale Reynolds number up to 240 show that the random-Taylor scenario ?a2???aC2? ? ?aL2?, accompanied by strong antialignment between the vectors aL and aC, is indeed increasingly valid at higher Reynolds number. Mutual cancellation between aL and aC also leads to the solenoidal part of a being small compared to its irrotational part. Results for spectra in wave number space indicate that, at a given Reynolds number, the random Taylor hypothesis has greater validity at decreasing scale sizes. Finally, comparisons with DNS data in Gaussian random fields show that the mutual cancellation between aL and aC is essentially a kinematic effect, although the Reynolds number trends are made stronger by the dynamics implied in the Navier–Stokes equations.","turbulence; convection; acceleration; fluctuations","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","","","","",""
"uuid:cd628242-f7ed-4a9b-8c3d-3c27692e9f19","http://resolver.tudelft.nl/uuid:cd628242-f7ed-4a9b-8c3d-3c27692e9f19","Effect of predictor-corrector filtering on the stability and spatial resolution of iterative PIV interrogation","Schrijer, F.F.J.; Scarano, F.","","2008","The stability and resolution of iterative PIV image analysis methods is investigated. The study focuses on the effects of stabilization by means of spatial filtering when implemented into the iterative process. Two filtering approaches are studied: predictor and corrector filtering respectively. A family of convolution filters is proposed, which allows to vary the filtering strength in a systematic way and primarily affects the system stability and to a smaller extent its spatial response. A critical value for the filter parameter is identified which guarantees the stability of the iterative process. A theoretical analysis is provided that determines the asymptotic properties of the iterative method with varying filter parameters. The study is completed with a numerical assessment and concludes with an application to real experiments, showing the consequence of an incorrect implementation of the iterative scheme under experimental conditions.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b6ff46d6-78c8-4c2b-abeb-82ecd726c8f0","http://resolver.tudelft.nl/uuid:b6ff46d6-78c8-4c2b-abeb-82ecd726c8f0","Design of a Co-Planar Airborne Separation Display","Ellerbroek, J.; Brantegem, K.C.R.; Van Paassen, M.M.; Mulder, M.","","2013","This paper describes a concept for a coplanar airborne self-separation display, which is designed to aid pilots in their separation task, by visualizing the possibilities for conflict resolution that the airspace provides. This study is a part of an ongoing research toward the design of a constraint-based 3-D separation assistance interface that can present all the relevant properties of the spatiotemporal separation problem. A display concept is proposed that presents speed, heading, and altitude action possibilities in two planar projections of the maneuver action space. The interface also visualizes how these projections interact with each other.","Ecological Interface Design (EID); situation awareness; self-separation; Airborne Separation Assistance System (ASAS)","en","journal article","","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:a9469dda-bf70-4410-966a-4063e7529588","http://resolver.tudelft.nl/uuid:a9469dda-bf70-4410-966a-4063e7529588","The rocky road to the upper atmosphere; NASA's quest to create long-term platforms in the stratosphere","Pagitz, M.","","2011","A recent program by NASA aims to develop balloons capable of carrying payloads of several tonnes to above 99% of the Earth's atmosphere for up to a hundred days. However, the road to the stratosphere turned out to be much harder and longer than expected","stratosphere; platforms","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9e03ee02-e864-44c2-95e5-a8707c48c6a9","http://resolver.tudelft.nl/uuid:9e03ee02-e864-44c2-95e5-a8707c48c6a9","Weight reductions for the airbus A380; postbuckling of the A380 VTP skin panels","Kroese, R.","","2014","The skin panels of the Vertical Tail Plane (VTP) are the largest single piece composite components assembled on the Airbus A380. By allowing postbuckling to these skin panels might result in severe weight reductions for the VTP of the A380. The goal of the study is to give an indication of possible weight reductions by allowing postbuckling to the skin panels of the VTP","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9eb052d5-c93b-411b-ae93-bc95cb78eb44","http://resolver.tudelft.nl/uuid:9eb052d5-c93b-411b-ae93-bc95cb78eb44","Atmos: Transitioning the future; the design of an autonomous UAV system that effectively combines VTOL and cruise flight","De Groot, J.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:32c69aeb-6467-435c-be22-52f2b44d911a","http://resolver.tudelft.nl/uuid:32c69aeb-6467-435c-be22-52f2b44d911a","Automatic Registration of Terrestrial Laser Scanning Point Clouds using Panoramic Reflectance Images","Kang, Z.; Li, J.; Zhang, L.; Zhao, Q.; Zlatanova, S.","","2009","This paper presents a new approach to the automatic registration of terrestrial laser scanning (TLS) point clouds using panoramic reflectance images. The approach follows a two-step procedure that includes both pair-wise registration and global registration. The pair-wise registration consists of image matching (pixel-to-pixel correspondence) and point cloud registration (point-to-point correspondence), as the correspondence between the image and the point cloud (pixel-to-point) is inherent to the reflectance images. False correspondences are removed by a geometric invariance check. The pixel to-point correspondence and the computation of the rigid transformation parameters (RTPs) are integrated into an iterative process that allows for the pair-wise registration to be optimised. The global registration of all point clouds is obtained by a bundle adjustment using a circular self-closure constraint. Our approach is tested with both indoor and outdoor scenes acquired by a FARO LS 880 laser scanner with an angular resolution of 0.036º and 0.045º, respectively. The results show that the pair-wise and global registration accuracies are of millimetre and centimetre orders, respectively, and that the process is fully automatic and converges quickly.","point cloud; registration; LIDAR; terrestrial laser scanning; automation; image matching","en","journal article","MDPI AG","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:8419c881-e2a3-47d8-a6c3-496c8fae9535","http://resolver.tudelft.nl/uuid:8419c881-e2a3-47d8-a6c3-496c8fae9535","Particle image velocimetry measurements of a shock wave/turbulent boundary layer interaction","Humble, R.A.; Scarano, F.; Van Oudheusden, B.W.","","2007","","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:22b90d92-9e63-4fa0-8d6e-2106912e23f9","http://resolver.tudelft.nl/uuid:22b90d92-9e63-4fa0-8d6e-2106912e23f9","Preprocessing of gravity gradients at the GOCE high-level processing facility","Bouman, J.; Rispens, S.; Gruber, T.; Koop, R.; Schrama, E.; Visser, P.; Tscherning, C.C.; Veicherts, M.","","2008","One of the products derived from the gravity field and steady-state ocean circulation explorer (GOCE) observations are the gravity gradients. These gravity gradients are provided in the gradiometer reference frame (GRF) and are calibrated in-flight using satellite shaking and star sensor data. To use these gravity gradients for application in Earth scienes and gravity field analysis, additional preprocessing needs to be done, including corrections for temporal gravity field signals to isolate the static gravity field part, screening for outliers, calibration by comparison with existing external gravity field information and error assessment. The temporal gravity gradient corrections consist of tidal and nontidal corrections. These are all generally below the gravity gradient error level, which is predicted to show a 1/f behaviour for low frequencies. In the outlier detection, the 1/f error is compensated for by subtracting a local median from the data, while the data error is assessed using the median absolute deviation. The local median acts as a high-pass filter and it is robust as is the median absolute deviation. Three different methods have been implemented for the calibration of the gravity gradients. All three methods use a high-pass filter to compensate for the 1/f gravity gradient error. The baseline method uses state-of-the-art global gravity field models and the most accurate results are obtained if star sensor misalignments are estimated along with the calibration parameters. A second calibration method uses GOCE GPS data to estimate a low-degree gravity field model as well as gravity gradient scale factors. Both methods allow to estimate gravity gradient scale factors down to the 10?3 level. The third calibration method uses high accurate terrestrial gravity data in selected regions to validate the gravity gradient scale factors, focussing on the measurement band. Gravity gradient scale factors may be estimated down to the 10?2 level with this method.","GOCE; High-level processing facility; Gravity gradients; Preprocessing; Calibration","en","journal article","Springer","","","","","","","","Aerospace Engineering","Delft Institute of Earth Observation and Space Systems, DEOS","","","",""
"uuid:f3bdf987-1f2d-45ed-97a1-67c2502b4a8e","http://resolver.tudelft.nl/uuid:f3bdf987-1f2d-45ed-97a1-67c2502b4a8e","Een toekomst met historie: Groot onderhoud van sociale huurwoningen te Culemborg","Dubbeling, D.J.","","2015","Voor groot onderhoud van woningen in Culemborg is aangehaakt op historische gebouwen in de regio. De werkzaamheden zijn aangegrepen om ook de openbare ruimte te verbeteren. De wijk heeft weer een toekomst.","","nl","journal article","BIM Media","","","","","","","","Aerospace Engineering","OTB","","","",""
"uuid:3f915bd5-1705-4526-8b4c-1b7ec8fc8fb2","http://resolver.tudelft.nl/uuid:3f915bd5-1705-4526-8b4c-1b7ec8fc8fb2","Perlan, reaching for high-flung pearls; and international team creates an unpowered aircraft to reach for an elusive cloud","Fymat, S.; Sigler, D.; Halverson, K.","","2012","","Perlan Project","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:37c85b69-451f-463c-bb61-48db2162f1c9","http://resolver.tudelft.nl/uuid:37c85b69-451f-463c-bb61-48db2162f1c9","Quantitative measurement of the lifetime of localized turbulence in pipe flow","Kuik, D.J.; Poelma, C.; Westerweel, J.","","2010","Transition to turbulence in a pipe is characterized by the increase of the characteristic lifetimes of localized turbulent spots (‘puffs’) with increasing Reynolds number (Re). Previous experiments are based on visualization or indirect measurements of the lifetime probability. Here we report quantitative direct measurements of the lifetimes based on accurate pressure measurements combined with laser Doppler anemometry (LDA). The characteristic lifetime is determined directly from the lifetime probability. It is shown that the characteristic lifetime does not diverge at finite Re, and follows an exponential scaling for the observed range 1725 4 hrs. We suggest that tidal forcing by Triton could play a role in exciting the waves responsible for the velocity variations of the observed period.","infrared; planetary systems; planets and satellites: Neptune; atmospheres","en","journal article","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:d5a9100c-23f7-4011-929c-44f099299215","http://resolver.tudelft.nl/uuid:d5a9100c-23f7-4011-929c-44f099299215","Evaluation of integral forces and pressure fields from planar velocimetry data for incompressible and compressible flows","Van Oudheusden, B.W.; Scarano, F.; Roosenboom, E.W.M.; Casimiri, E.W.F.; Souverein, L.J.","","2007","","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:be6751f8-3459-4f68-ae3b-9f92f70cc47f","http://resolver.tudelft.nl/uuid:be6751f8-3459-4f68-ae3b-9f92f70cc47f","Cycling 7.000km through the heart of Africa","De Gaay Fortman, R.","","2010","Promoting renewable energy and raising funds for the solarisation of schools in Zambia on a bicycle","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:60eb773c-fa67-49c4-a592-a1894c7b25b2","http://resolver.tudelft.nl/uuid:60eb773c-fa67-49c4-a592-a1894c7b25b2","Bringing a patent to life; a lightweight composite exhaust system for automotive applications","Ridolfi, G.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:877c9f4b-3088-4c93-ae48-2ea36f97af5e","http://resolver.tudelft.nl/uuid:877c9f4b-3088-4c93-ae48-2ea36f97af5e","The times they are a-changin'","Gupta, S.","","2013","The global civil aviation industry is currently dominated by two major powers in the form of Boeing and Airbus. The market has been characterized as a duopoly. However, this status quo is by no means immutable. Over the coming decades, growing demand might lead to other companies making their mark on the global aviation market. High time to look at some of the past, current and future developments within the industry.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7dd1601c-f623-46d4-9a94-61dc09cd2d4d","http://resolver.tudelft.nl/uuid:7dd1601c-f623-46d4-9a94-61dc09cd2d4d","The Dutch giant leap for mankind; an interview with Ben Droste about his ambition to commercialize space flight","Van Gent, I.; Schneiders, J.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:63580df7-6c6e-4920-ba8a-6e1d72fd8f20","http://resolver.tudelft.nl/uuid:63580df7-6c6e-4920-ba8a-6e1d72fd8f20","Summary of Data Analysis of the YES2 Tethered SpaceMail Experiment","Kruijff, M.; Belokonov, I.; Van der Heide, E.J.; Ockels, W.J.; Gill, E.","","2008","","","en","journal article","","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:32566fa2-5fcf-424d-9aec-73f5c2a67604","http://resolver.tudelft.nl/uuid:32566fa2-5fcf-424d-9aec-73f5c2a67604","Tuning the stress induced martensitic formation in titanium alloys by alloy design","Li, C.; Chen, J.H.; Wu, X.; Wang, W.; Van der Zwaag, S.","","2012","","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:427a1b85-f95d-457a-ab47-d5864d39edb9","http://resolver.tudelft.nl/uuid:427a1b85-f95d-457a-ab47-d5864d39edb9","How far is smart rotor research and what steps need to be taken to build a full-scale prototype?","Bernhammer, L.O.; Van Kuik, G.A.M.; De Breuker, R.","","2014","During the last decade research on the field of smart rotor has advanced significantly. Fundamental aerodynamics, structural and control concepts have been established and simulators created for distributed flaps on wind turbine blades, which are considered the most promising option. Also a proof of concept has been done under laboratory conditions. However, the results obtained under these conditions can only be partially transfer to the real application as the control authority of smart rotors is limited compared to full pitch control. The steps that need to be taken before smart rotors can be successfully exploited are in the design of reliable systems that can operate under environmental conditions without inspections. Besides that, other potential advantages of distributed control need to be established such as the effect on other components of a wind turbine for example the gear box or the power system. Finally, it is necessary to investigate what benefits can be achieved if blades are designed with distributed control right from the start instead of applying control schemes to already existing turbines.","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:68a4fed4-f62c-4fe3-b2c8-f73becc30eda","http://resolver.tudelft.nl/uuid:68a4fed4-f62c-4fe3-b2c8-f73becc30eda","Three-Dimensional Laser Imaging as a Valuable Tool for Specifying Changes in Breast Shape After Augmentation Mammaplasty","Esme, D.L.; Bucksch, A.; Beekman, W.H.","","2008","Background Three-dimensional (3D) terrestrial laser scanning (TLS) is a valuable method for measuring shapes of objects and for obtaining quantitative measurements. These qualities of the 3D laser scanner have proved to be useful in reconstructive breast surgery. This study investigated various 3D parameters to obtain an optimal objective visualization of the breast after cosmetic augmentation mammaplasty. Methods The objects are represented in a point cloud, which comprises millions of x, y, and z coordinates representing a virtual image. The quantification of 3D points shows changes in height (z coordinate) at any chosen point on the augmented breast (x and y coordinates). To give visual feedback on the change in dimensions, a color elevation scheme was applied on the reconstructed surface of the breast. As a quantifying description, a sagittal B-spline was chosen in a plane through the nipple to obtain the breast shape via the lateral profile. Results Pre- and postoperative clear images were obtained. The color elevation model showed an increased projection and upper pole fullness after augmentation. The B-spline showed the gain in projection in a sagittal plane through the nipple. Conclusions Three-dimensional TLS is capable of objectifying changes in shape after augmentation mammaplasty. This imaging technique represents superior visualization of the breast shape and can serve as a valuable tool to determine the changing dimensions of the breasts after augmentation mammaplasty.","3D Terrestrial laser scanning; Augmentation mammaplasty","en","journal article","Springer","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:3683b134-c13b-4ed9-bd6c-d92cabeff888","http://resolver.tudelft.nl/uuid:3683b134-c13b-4ed9-bd6c-d92cabeff888","Taking delivery of a KLM Boeing 737 in Seattle; a great opportunity of blending commercial flying with a Delft Aerospace Engineering background","Van der Sluis, R.","","2011","","Boeing 737","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:969b6c41-fd13-4b93-a5ec-dd4a1adefceb","http://resolver.tudelft.nl/uuid:969b6c41-fd13-4b93-a5ec-dd4a1adefceb","Dielectric behavior and phase transition in perovskite oxide Pb(Fe1/2Nb1/2)1?xTixO3 single crystal","Jia, Y.; Luo, H.; Or, S.W.; Wang, Y.; Chan, H.L.W.","","2009","Perovskite oxide Pb(Fe1/2Nb1/2)0.52Ti0.48O3 crystals, which were grown using a modified Bridgman method, show a high low-frequency dielectric constant response at room temperature. The Curie phase transition occurs at 523 K. The characteristic frequency of the dielectric dispersion versus the inverse of temperature obeys an Arrhenius relation, which shows a thermally activated behavior. The thermal activation energy for relaxation was found to be ? 0.14?eV. The high dielectric permittivity was attributed to oxygen vacancies and conduction via hopping carriers.","crystal growth from melt; ferroelectric Curie temperature; ferroelectric materials; ferroelectric transitions; hopping conduction; iron compounds; lead compounds; niobium compounds; permittivity; vacancies (crystal)","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f402b7b5-979e-472c-959f-9f567f5a4b22","http://resolver.tudelft.nl/uuid:f402b7b5-979e-472c-959f-9f567f5a4b22","Designing mechatronic systems; understanding and using the complexity of modern products","Foeken, M.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:af038f42-0d9d-47da-80f5-580fc85de29a","http://resolver.tudelft.nl/uuid:af038f42-0d9d-47da-80f5-580fc85de29a","Equatorial electrodynamics and neutral background in the Asian sector during the 2009 stratospheric sudden warming","Liu, H.; Yamamoto, M.; Tulasi Ram, S.; Tsugawa, T.; Otsuka, Y.; Stolle, C.; Doornbos, E.; Yumoto, K.; Nagatsuma, T.","","2011","Using ground observations of total electron content (TEC) and equatorial electrojet (EEJ) in the Asian sector, along with plasma and neutral densities obtained from the CHAMP satellite, we investigate the ionospheric electrodynamics and neutral background in this longitude sector during the major stratospheric sudden warming (SSW) in January 2009. Our analysis reveals the following prominent features. First, the TEC response in tropical regions is strongly latitude dependent, with monotonic depletion at the dip equator but a semidiurnal perturbation at low latitudes. Second, the TEC semidiurnal perturbation possesses a significant hemispheric asymmetry in terms of onset date and magnitude. It starts on the same day as the SSW peak in the Northern Hemisphere but 2 days later in the Southern Hemisphere. Its magnitude is twice as strong in the north than in the south. Third, strong counter electrojet occurs in the afternoon, following the strengthening of the eastward EEJ in the morning. Fourth, semidiurnal perturbation in both TEC and EEJ possesses a phase shift, at a rate of about 0.7 h/day. Comparisons with results reported in the Peruvian sector reveal clear longitude dependence in the amplitude and hemispheric asymmetry of the semidiurnal perturbation. Finally, thermospheric density undergoes ?25% decrease at low latitudes in the afternoon local time sector during the SSW, indicating significant cooling effects in the tropical upper thermosphere.","equatorial electrodynamics; stratosphere warming; thermosphere cooling; thermosphere-ionosphere coupling; vertical coupling","en","journal article","American Geophysical Union","","","","","","","2012-02-17","Aerospace Engineering","Space Engineering","","","",""
"uuid:78c3fa17-3977-46a5-a113-17f99a403f2d","http://resolver.tudelft.nl/uuid:78c3fa17-3977-46a5-a113-17f99a403f2d","Short and zero baseline analysis of GPS L1 C/A, L5Q, GIOVE E1B, and E5aQ signals","De Bakker, P.F.; Tiberius, C.C.J.M.; Van der Marel, H.; Van Bree, R.J.P.","","2011","Stochastic properties of GNSS range measurements can accurately be estimated using a geometry-free short and zero baseline analysis method. This method is now applied to dual-frequency measurements from a new field campaign. Results are presented for the new GPS L5Q and GIOVE E5aQ wideband signals, in addition to the GPS L1 C/A and GIOVE E1B signals. As expected, the results clearly show the high precision of the new signals, but they also show, rather unexpectedly, significant, slowly changing variations in the pseudorange code measurements that are probably a result of strong multipath interference on the data. Carrier phase measurement noise is assessed on both frequencies, and finally successful mixed GPS-GIOVE double difference ambiguity resolution is demonstrated.","GPS; GIOVE; Multi-constellation; Geometry-free; Short baseline; Zero baseline; Multipath; Code noise; Phase noise; Undifferenced; Single, double, triple difference","en","journal article","Springer Verlag","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:aee7a88f-72cc-4d2d-b3de-164c7448c5dc","http://resolver.tudelft.nl/uuid:aee7a88f-72cc-4d2d-b3de-164c7448c5dc","Investigation of a turbulent spot and a tripped turbulent boundary layer flow using time-resolved tomographic PIV","Schröder, A.; Geisler, R.; Elsinga, G.E.; Scarano, F.; Dierksheide, U.","","2007","In this feasibility study the tomographic PIV technique has been applied to time resolved PIV recordings for the study of the growth of a turbulent spot in a laminar flat plate boundary layer and to visualize the topology of coherent flow structures within a tripped turbulent flat plate boundary layer flow. The experiments are performed around (Re x )1/2 ? 450 in a low speed wind-tunnel using four high speed CMOS cameras operating up to 5 kHz. The volume illumination required a multiple-reflection system able to intensify light intensity within the measurement volume. This aspect is deemed essential when a high-speed tomographic PIV system is applied in air flows. The particle image recordings are used for a three dimensional tomographic reconstruction of the light intensity distribution within the illuminated volume. Each pair of reconstructed three-dimensional light distributions is analyzed by 3D spatial cross-correlation using iterative multi-grid schemes with volume-deformation, yielding a correlated time sequence of three-dimensional instantaneous velocity vector volumes. The coherent structures organization is analyzed by 3D-vorticity and -swirling-strength iso-surfaces visualization. In both flow types streaks and hairpin-like or arch vortical structures are most prominent. The data gives insight into the role of these structures for the spatio-temporal arrangement of the wall normal flow exchange mechanisms, especially of the instantaneous Reynolds stress events Q2 and Q4. A description of different self-sustainable flow organizations based on modifications of the hairpin-vortex- and streak-models is given. Two preliminary results are essential: Self-sustainability of a coherent vortical structure depends on the ability to entrain high momentum fluid, initially Q4. And, stream-wise swirl at the near-wall region of arch or hairpin-like vortices has been observed to be rare.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:bb1d9150-502f-4b94-88fd-498c248c7c15","http://resolver.tudelft.nl/uuid:bb1d9150-502f-4b94-88fd-498c248c7c15","Probabilistic collocation used in a Two-Step approached for efficient uncertainty quantification in computational fluid dynamics","Loeven, G.J.A.; Bijl, H.","","2009","In this paper a Two-Step approach is presented for uncertainty quantification for expensive problems with multiple uncertain parameters. Both steps are performed using the Probabilistic Collocation method. The first step consists of a sensitivity analysis to identify the most important parameters of the problem. The sensitivity derivatives are obtained using a first or second order Probabilistic Collocation approximation. For the most important parameters the probability distribution functions are propagated using the Probabilistic Collocation method using higher order approximations. The Two-Step approach is demonstrated for flow around a NACA0012 airfoil with eight uncertain parameters in the free stream conditions and geometry. The first step identified the freestream velocity, angle of attack, and the camber of the airfoil as the three most important parameters. In the second step the probability distributions of all three parameters are propagated using higher order Probabilistic Collocation approximations. Statistical properties of the lift and drag are obtained, as well as uncertainty bounds for the pressure and skinfriction on the surface of the airfoil","probabilistic collocation; polynomial chaos; computational fluid dynamics; uncertainty quantification; sensitivity analysis","","journal article","Tech Science Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4194bdae-23a5-4850-a6bd-339e632c27af","http://resolver.tudelft.nl/uuid:4194bdae-23a5-4850-a6bd-339e632c27af","The sea level fingerprint of recent ice mass fluxes","Bamber, J.; Riva, R.E.M.","","2010","The sea level contribution from glacial sources has been accelerating during the first decade of the 21st Century (Meier et al., 2007; Velicogna, 2009). This contribution is not distributed uniformly across the world's oceans due to both oceanographic and gravitational effects. We compute the sea level signature for ice mass fluxes due to changes in the gravity field, Earth's rotation and related effects for the nine year period 2000–2008. Mass loss from Greenland results in a relative sea level (RSL) reduction for much of North Western Europe and Eastern Canada. RSL rise from this source is concentrated around South America. Losses in West Antarctica marginally compensate for this and produce maxima along the coastlines of North America, Australia and Oceania. The combined far-field pattern of wastage from all ice melt sources, is dominated by losses from the ice sheets and results in maxima at latitudes between 20° N and 40° S across the Pacific and Indian Oceans, affecting particularly vulnerable land masses in Oceania. The spatial pattern of RSL variations from ice mass losses used in this study is time-invariant and cumulative. Thus, sea level rise, based on the gravitational effects from the ice losses considered here, will be amplified for this sensitive region.","","en","journal article","Copernicus Publications","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:f73fe8f3-707b-42e2-82a4-05d7674604f8","http://resolver.tudelft.nl/uuid:f73fe8f3-707b-42e2-82a4-05d7674604f8","RadioAstron as a target and as an instrument: Enhancing the Space VLBI mission’s scientific output","Duev, D.A.; Zakhvatkin, M.V.; Stepanyants, V.A.; Molera Calvés, G.; Pogrebenko, S.V.; Gurvits, L.I.; Cimò, G.; Bocanegra Bahamón, T.M.","","2015","Context. The accuracy of orbit determination has a strong impact on the scientific output of the Space VLBI mission RadioAstron. Aims. The aim of this work is to improve the RadioAstron orbit reconstruction by means of sophisticated dynamical modelling of its motion in combination with multi-station Doppler tracking of the RadioAstron spacecraft. Methods. The improved orbital solution is demonstrated using Doppler measurements of the RadioAstron downlink signal and by correlating VLBI observations made by RadioAstron with ground-based telescopes using the enhanced orbit determination data. Results. Orbit determination accuracy has been significantly improved from ~600 m in 3D position and ~2 cm/s in 3D velocity to several tens of metres and mm/s, respectively.","astrometry; techniques: interferometric; instrumentation: interferometers; instrumentation: miscellaneous","en","journal article","EDP Sciences","","","","","","","","Aerospace Engineering","Department of Astrodynamics and Space Missions","","","",""
"uuid:337c3436-a1fd-44de-ad4d-379425746aad","http://resolver.tudelft.nl/uuid:337c3436-a1fd-44de-ad4d-379425746aad","Dutch space; interview with Arnaud de Jong, CEO","Wink, J.; Sabbapathy, R.","De Jong, A. (contributor)","2014","Dutch Space, the largest space company in the Netherlands and part of Airbus Defence and Space, appointed a new CEO last year. The Leonardo Times sat down with the CEO Arnaud de Jong for an interview. We discuss his career, developments in Dutch Space, his take on competition in the commercial space domain and his future outlook on European and International space markets.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6ab95051-ee22-4eae-b897-9455f1bb43f9","http://resolver.tudelft.nl/uuid:6ab95051-ee22-4eae-b897-9455f1bb43f9","""Ever had an extraterrestrial experience?"" ; interview with first Dutch-born astronaut Lodewijk van den Berg","De Koning, R.V.; Motsyk, O.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:841e5e40-c217-4949-879a-435faf8178a1","http://resolver.tudelft.nl/uuid:841e5e40-c217-4949-879a-435faf8178a1","Attitude control system of the Delfi-n3Xt satellite","Reijneveld, J.; Choukroun, D.","","2013","This work is concerned with the development of the attitude control algorithms that will be implemented on board of the Delfi-n3xt nanosatellite, which is to be launched in 2013. One of the mission objectives is to demonstrate Sun pointing and three axis stabilization. The attitude control modes and the associated algorithms are described. The control authority is shared between three body-mounted magnetorquers (MTQ) and three orthogonal reaction wheels. The attitude information is retrieved from Sun vector measurements, Earth magnetic field measurements, and gyro measurements. The design of the control is achieved as a trade between simplicity and performance. Stabilization and Sun pointing are achieved via the successive application of the classical Bdot control law and a quaternion feedback control. For the purpose of Sun pointing, a simple quaternion estimation scheme is implemented based on geometric arguments, where the need for a costly optimal filtering algorithm is alleviated, and a single line of sight (LoS) measurement is required ? here the Sun vector. Beyond the three-axis Sun pointing mode, spinning Sun pointing modes are also described and used as demonstration modes. The three-axis Sun pointing mode requires reaction wheels and magnetic control while the spinning control modes are implemented with magnetic control only. In addition, a simple scheme for angular rates estimation using Sun vector and Earth magnetic measurements is tested in the case of gyro failures. The various control modes performances are illustrated via extensive simulations over several orbits time spans. The simulated models of the dynamical space environment, of the attitude hardware, and the onboard controller logic are using realistic assumptions. All control modes satisfy the minimal Sun pointing requirements allowed for power generation.","","en","journal article","EDP sciences","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:a1de399f-fd5d-44f8-932e-805fee00bd4a","http://resolver.tudelft.nl/uuid:a1de399f-fd5d-44f8-932e-805fee00bd4a","Lidar uncertainty and beam averaging correction","Giyanani, A.H.; Bierbooms, W.A.A.M.; Van Bussel, G.J.W.","","2015","Remote sensing of the atmospheric variables with the use of Lidar is a relatively new technology field for wind resource assessment in wind energy. A review of the draft version of an international guideline (CD IEC 61400-12-1 Ed.2) used for wind energy purposes is performed and some extra atmospheric variables are taken into account for proper representation of the site. A measurement campaign with two Leosphere vertical scanning WindCube Lidars and metmast measurements is used for comparison of the uncertainty in wind speed measurements using the CD IEC 61400-12-1 Ed.2. The comparison revealed higher but realistic uncertainties. A simple model for Lidar beam averaging correction is demonstrated for understanding deviation in the measurements. It can be further applied for beam averaging uncertainty calculations in flat and complex terrain.","OA-Fund TU Delft","en","journal article","Copernicus Publications","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:32c570be-35a5-4b47-bc2c-0eb1bc947dbe","http://resolver.tudelft.nl/uuid:32c570be-35a5-4b47-bc2c-0eb1bc947dbe","Feed-Forward Control of Kite Power Systems","Fechner, U.; Schmehl, R.","","2014","Kite power technology is a novel solution to harvest wind energy from altitudes that can not be reached by conventional wind turbines. The use of a lightweight but strong tether in place of an expensive tower provides an additional cost advantage, next to the higher capacity factor. This paper describes a method to estimate the wind velocity at the kite using measurement data at the kite and at the ground. Focussing on a kite power system, which is converting the traction power of a kite in a pumping mode of operation, a reel-out speed predictor is presented for use in feed-forward control of the tether reel-out speed of the winch. The results show, that the developed feedforward controller improves the force control accuracy by a factor of two compared to the previously used feedback controller. This allows to use a higher set force during the reel-out phase which in turn increases the average power output by more than 4 %. Due to its straightforward implementation and low computational requirements feedforward control is considered a promising technique for the reliable and efficient operation of traction-based kite power systems.","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:6f3ceca0-4b26-47ea-9f95-612cdef3c054","http://resolver.tudelft.nl/uuid:6f3ceca0-4b26-47ea-9f95-612cdef3c054","Decomposition of time-resolved tomographic PIV","Schmid, P.J.; Violato, D.; Scarano, F.","","2012","An experimental study has been conducted on a transitional water jet at a Reynolds number of Re = 5,000. Flow fields have been obtained by means of time-resolved tomographic particle image velocimetry capturing all relevant spatial and temporal scales. The measured threedimensional flow fields have then been postprocessed by the dynamic mode decomposition which identifies coherent structures that contribute significantly to the dynamics of the jet. Both temporal and spatial analyses have been performed. Where the jet exhibits a primary axisymmetric instability followed by a pairing of the vortex rings, dominant dynamic modes have been extracted together with their amplitude distribution. These modes represent a basis for the low-dimensional description of the dominant flow features.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy and Propulsion","","","",""
"uuid:0519a729-b906-4171-9a52-fcebdb3bf5cc","http://resolver.tudelft.nl/uuid:0519a729-b906-4171-9a52-fcebdb3bf5cc","A constrained generalised-? method for coupling rigid parallel chain kinematics and elastic bodies","Gransden, D.I.; Burkhard Bornemann, P.; Rose, M.; Nitzsche, F.","","2015","A problem arises from combining flexible rotorcraft blades with stiffer mechanical links, which form a parallel kinematic chain. This paper introduces a method for solving index-3 differential algebraic equations for coupled stiff and elastic body systems with closed-loop kinematics. Rigid body dynamics and elastic body mechanics are independently described according to convenient mathematical measures. Holonomic constraint equations couple both the parallel chain kinematics and describe the coupling between the rigid and continuum bodies. Lagrange multipliers enforce the kinetic conditions for both sets of constraints. Additionally, to prevent numerical inaccuracy from inverting stiff mechanical matrices, a scaling factor normalises the dynamic tangential stiffness matrix. Finally, example tests show the verification of the algorithm with respect to existing computational tests and the accuracy of the model for cases relevant to the problem definition.","dynamics; closed-chain kinematics; constraints; Lagrange multipliers; CG?; CG ?","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:740fb359-6b96-4623-95c3-7b9551b73ceb","http://resolver.tudelft.nl/uuid:740fb359-6b96-4623-95c3-7b9551b73ceb","A monomial chaos approach for efficient uncertainty quantification on nonlinear problems","Witteveen, J.A.S.; Bijl, H.","","2008","A monomial chaos approach is presented for efficient uncertainty quantification in nonlinear computational problems. Propagating uncertainty through nonlinear equations can be computationally intensive for existing uncertainty quantification methods. It usually results in a set of nonlinear equations which can be coupled. The proposed monomial chaos approach employs a polynomial chaos expansion with monomials as basis functions. The expansion coefficients are solved for using differentiation of the governing equations, instead of a Galerkin projection. This results in a decoupled set of linear equations even for problems involving polynomial nonlinearities. This reduces the computational work per additional polynomial chaos order to the equivalence of a single Newton iteration. Error estimates are derived, and monomial chaos is applied to uncertainty quantification of the Burgers equation and a two-dimensional boundary layer flow problem. The results are compared with results of the Monte Carlo method, the perturbation method, the Galerkin polynomial chaos method, and a nonintrusive polynomial chaos method.","uncertainty quantification; polynomial chaos; computational fluid dynamics; non deterministic approaches","en","journal article","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1ea2ab47-a595-46f9-a162-039c860512c9","http://resolver.tudelft.nl/uuid:1ea2ab47-a595-46f9-a162-039c860512c9","Three-dimensional instantaneous structure of a shock wave/turbulent boundary layer interaction","Humble, R.A.; Elsinga, G.E.; Scarano, F.; van Oudheusden, B.W.","","2009","","","en","journal article","Cambridge University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5c9f008a-d840-4840-a43d-22828b40a5d8","http://resolver.tudelft.nl/uuid:5c9f008a-d840-4840-a43d-22828b40a5d8","The dive into post-grad life: What happens with the graduated student?","Aas, C.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b162e6ca-ecf2-4d9d-a198-ca0be41376ca","http://resolver.tudelft.nl/uuid:b162e6ca-ecf2-4d9d-a198-ca0be41376ca","Advancing aerospace technology; an interview with the general director of the NLR","Schneiders, J.; Wamiti, L.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0e9ea54b-4c4f-4f84-8112-b43565c459b4","http://resolver.tudelft.nl/uuid:0e9ea54b-4c4f-4f84-8112-b43565c459b4","Modelling airline operations control","Bourafa, S.","","2013","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e9ffb2a1-64b2-4315-b026-677fe72d3818","http://resolver.tudelft.nl/uuid:e9ffb2a1-64b2-4315-b026-677fe72d3818","Nanostructured tracers for laser-based diagnostics in high-speed flows","Ghaemi, S.; Schmidt-Ott, A.; Scarano, F.","","2010","The potential application of aggregates of nanoparticles for high-speed flow diagnostics is investigated. Aluminum nanoparticles around 10 nm in diameter are produced by spark discharge in argon gas. Through rapid coagulation and oxidation, aggregates of small effective density are formed. They are characterized by microscopy and their aerodynamics and optical properties are theoretically evaluated. The performance of the aggregates is experimentally investigated across an oblique shock wave in a supersonic wind tunnel of 3 × 3 cm2 cross-section at Mach 2. Particle image velocimetry is used to quantify the time response of the aggregates. The investigations are also carried out on compact titanium agglomerates to provide a base for comparison. The results yield a relaxation time of 0.27 ?s for the nanostructured aluminum aggregates, which is an order of magnitude reduction with respect to the compact titanium nanoparticles. This work demonstrates the applicability of nanostructured aggregates for laser-based diagnostics in supersonic and hypersonic flows.","tracer particle, PIV, shock wave relaxation time, nanostructured aggregate, spark, discharge","en","journal article","Institute of Physics","","","","","","","","Aerospace Engineering","Department of Aerodynamics","","","",""
"uuid:f14b1254-6814-4de0-a822-2e45a0901f93","http://resolver.tudelft.nl/uuid:f14b1254-6814-4de0-a822-2e45a0901f93","Jovian discoveries; how Galileo explored the Jovian system fifteen years ago","Willems, T.","","2011","Ever since the famous astronomer Galileo Galilei improved his telescope making it possible to look further into space, people have been staring through telescopes into the far distance in search of new worlds. In January 1610 Galilei discovered the four biggest satellites of Jupiter: Io, Europa, Ganymede and Callisto, later to be known as the Galilean moons. About fifteen years ago the eponymous NASA spacecraft 'Galileo' entered an orbit around Jupiter to discover the Galilean moons once again. But this time from a much smaller distance and with a larger set of tools than ever before","Jovian, Galileo","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:68e67c64-1bfa-4d8a-96dc-cb780b9951a8","http://resolver.tudelft.nl/uuid:68e67c64-1bfa-4d8a-96dc-cb780b9951a8","Development of Generic Methodology for Designing a Structural Health Monitoring Installation Based on the Acoustic Emission Technique","Gagar, D.; Martinez, M.J.; Foote, P.","","2014","The Acoustic Emission (AE) technique can be used to perform damage detection and localisation for structural health monitoring purposes. Implementation in aircraft structures however poses a significant challenge as its performance in terms of damage detection and localisation is not well understood when used with complex structural geometries and variable operational service environments. This paper presents initial developments towards a generic methodology for optimal design of a structural health monitoring installation based on the acoustic emission technique. Performance verification of the AE monitoring process was classified into two stages. The first is a mainly empirical process for quantitatively characterising AE generation from damage using the Probability of Hit (POH) metric developed and presented in this study. The second is a combination of mathematical, numerical and empirical modeling to characterise AE propagation and detection which can also be used to determine optimal system configuration and sensor design. It was found that for Structural Health Monitoring (SHM) techniques to be part of wider structural integrity programmes, there is need for standards that recommend best practices as well as providing specification of acceptable levels of performance in terms of damage detection and location.","acoustic emission; structural health monitoring","en","journal article","Elsevier","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:9efd6c5c-52f1-41ff-8676-2c9e7875b2d6","http://resolver.tudelft.nl/uuid:9efd6c5c-52f1-41ff-8676-2c9e7875b2d6","Space mining; is the universe up for grabs?","Van Ingen, J.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:fb95b512-912b-4056-bbda-68c67e631a6d","http://resolver.tudelft.nl/uuid:fb95b512-912b-4056-bbda-68c67e631a6d","Analysis and modeling of the seasonal South China Sea temperature cycle using remote sensing","Twigt, D.J.; De Goede, E.D.; Schrama, E.J.O.; Gerritsen, H.","","2007","","South China Sea; Baroclinic temperature model; Reduced depth modeling; Altimeter data; Radiometer data; Temperature nudging","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:adaa8a18-aede-454a-933c-61b35741b07d","http://resolver.tudelft.nl/uuid:adaa8a18-aede-454a-933c-61b35741b07d","Three-dimensional flow structures and unsteady forces on pitching and surging revolving flat plates","Percin, M.; Van Oudheusden, B.W.","","2015","Tomographic particle image velocimetry was used to explore the evolution of three-dimensional flow structures of revolving low-aspect-ratio flat plates in combination with force measurements at a Reynolds number of 10,000. Two motion kinematics are compared that result in the same terminal condition (revolution with constant angular velocity and 45? angle of attack) but differ in the motion during the buildup phase: pitching while revolving at a constant angular velocity; or surging with a constant acceleration at a fixed angle of attack. Comparison of force histories shows that the pitching wing generates considerably higher forces during the buildup phase which is also predicted by a quasi-steady model quite accurately. The difference in the buildup phases affects the force histories until six chords of travel after the end of buildup phase. In both cases, a vortex system that is comprised of a leading-edge vortex (LEV), a tip vortex and a trailing edge vortex is formed during the initial period of the motion. The LEV lifts off, forms an arch-shaped structure and bursts into substructures, which occur at slightly different phases of the motions, such that the revolving–surging wing flow evolution precedes that of the revolving–pitching wing. The delay is shown to be in accordance with the behavior of the spanwise flow which is affected by the interaction between the tip vortex and revolving dynamics. Further analysis shows that the enhanced force generation of the revolving–pitching wing during the pitch-up phase originates from: (1) increased magnitude and growth rate of the LEV circulation; (2) relatively favorable position and trajectory of the LEV and the starting vortex; and (3) generation of bound circulation during the pitching motion, whereas that of the revolving–surging wing is negligible in the acceleration phase.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:cc69f0c2-e480-45e2-bc93-478bce141bf1","http://resolver.tudelft.nl/uuid:cc69f0c2-e480-45e2-bc93-478bce141bf1","Real-time single-frequency precise point positioning: Accuracy assessment","Van Bree, R.J.P.; Tiberius, C.C.J.M.","","2011","The performance of real-time single-frequency precise point positioning is demonstrated in terms of position accuracy. This precise point positioning technique relies on predicted satellite orbits, predicted global ionospheric maps, and in particular on real-time satellite clock estimates. Results are presented using solely measurements from a user receiver on the L1-frequency (C1 and L1), for almost 3 months of data. The empirical standard deviations of the position errors in North and East directions are about 0.15 m, and in Up direction about 0.30 m. The 95% errors are about 0.30 m in the horizontal directions, and 0.65 m in the vertical. In addition, single-frequency results of six receivers located around the world are presented. This research reveals the current ultimate real-time single-frequency positioning performance. To put these results into perspective, a case study is performed, using a moderately priced receiver with a simple patch antenna.","Single frequency; Precise point positioning; Real-time satellite clocks; Real-time positioning results","en","journal article","Springer Verlag","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:4b6ab71e-d2d2-4107-bc0b-343a70ef84de","http://resolver.tudelft.nl/uuid:4b6ab71e-d2d2-4107-bc0b-343a70ef84de","Get to the choppa! Internship at Eurocopter Deutschland","Houg, W.","","2011","","Eurocopter Deutschland","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:deef30c9-08fc-49f2-a7dd-6474a455931d","http://resolver.tudelft.nl/uuid:deef30c9-08fc-49f2-a7dd-6474a455931d","Direct strain energy harvesting in automobile tires using piezoelectric PZT–polymer composites","Van den Ende, D.A.; Van de Wiel, H.J.; Groen, W.A.; Van der Zwaag, S.","","2011","Direct piezoelectric strain energy harvesting can be used to power wireless autonomous sensors in environments where low frequency, high strains are present, such as in automobile tires during operation. However, these high strains place stringent demands on the materials with respect to mechanical failure or depolarization, especially at elevated temperatures. In this work, three kinds of ceramic–polymer composite piezoelectric materials were evaluated and compared against state-of-the-art piezoelectric materials. The new composites are unstructured and structured composites containing granular lead zirconate titanate (PZT) particles or PZT fibers in a polyurethane matrix. The composites were used to build energy harvesting patches which were attached to a tire and tested under simulated rolling conditions. The energy density of the piezoelectric ceramic–polymer composite materials is initially not as high as that of the reference materials (a macro-fiber composite and a polyvinylidene fluoride polymer). However, the area normalized power output of the composites after temperature and strain cycling is comparable to that of the reference devices because the piezoelectric ceramic–polymer composites did not degrade during operation.","smart tire; intelligent tire; pizeoelectric composite; PZT; PVDF; energy harvesting; strain energy harvesting","en","journal article","Institute of Physics Publishing","","","","","","","","Aerospace Engineering","NOVAM","","","",""
"uuid:9cf82c49-3e69-45d2-aee8-78727f8064cc","http://resolver.tudelft.nl/uuid:9cf82c49-3e69-45d2-aee8-78727f8064cc","Simulation and detection of flaws in pre-cured CFRP using laser displacement sensing","Miesen, N.; Sinke, J.; Groves, R.M.; Benedictus, R.","","2015","The novelty of the research is the detection of different types of flaws in the prepreg carbon fibre-reinforced fibres (CFRP) layup compared to in cured products. This paper presents the development of a new method for in situ detection of prepreg CFRP production flaws combining laser displacement sensors and analytical modelling. Experimental results are used to validate the results from the models. The pre-cured flaws are simulated to determine the needed specifications of the measurement system. In static and dynamic experiments, the typical production flaws are detected to demonstrate the use of laser displacement sensing as a preventative non-destructive evaluation (NDE) system. During the production of CFRP materials, flaws can be introduced due to the process of layup or curing. Once a production flaw is embedded and cured in the CFRP laminate, the damage is irreversible and it is expensive to rework or remanufacture the product. Laser displacement sensing is currently used in a wide range of applications in industrial manufacturing and is successfully assessed in this research as a preventative NDE system.","laser displacement sensing; preventative NDE; CFRP; layup process","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:8ec20886-8078-45b6-993e-491d67517f1a","http://resolver.tudelft.nl/uuid:8ec20886-8078-45b6-993e-491d67517f1a","The first Dutch human powered aircraft; pedalling through the sky using your own power","Van Kuijk, J.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2d1544ed-661b-464b-bce5-0c98d7c5dbf2","http://resolver.tudelft.nl/uuid:2d1544ed-661b-464b-bce5-0c98d7c5dbf2","Nonlinear Multivariate Spline-Based Control Allocation for High-Performance Aircraft","Tol, H.J.; De Visser, C.C.; Van Kampen, E.; Chu, Q.P.","","2014","High performance flight control systems based on the nonlinear dynamic inversion (NDI) principle require highly accurate models of aircraft aerodynamics. In general, the accuracy of the internal model determines to what degree the system nonlinearities can be canceled; the more accurate the model, the better the cancellation, and with that, the higher the performance of the controller. In this paper a new control system is presented that combines NDI with multivariate simplex spline based control allocation. We present three control allocation strategies which use novel expressions for the analytical Jacobian and Hessian of the multivariate spline models. Multivariate simplex splines have a higher approximation power than ordinary polynomial models, and are capable of accurately modeling nonlinear aerodynamics over the entire flight envelope of an aircraft. This new method, indicated as SNDI, is applied to control a high performance aircraft (F-16) with a large flight envelope. The simulation results indicate that the SNDI controller can achieve feedback linearization throughout the entire flight envelope, leading to a significant increase in tracking performance compared to ordinary polynomial based NDI.","nonlinear control; multivariate splines; control allocation","en","journal article","AIAA","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:31478142-f514-48f9-9281-552fbfc50860","http://resolver.tudelft.nl/uuid:31478142-f514-48f9-9281-552fbfc50860","The unmanned aerial vehicle; a small history of violence","De Koning, R.V.","","2013","At Aerospace Engineering, one can hardly miss the Unmanned Aerial Vehicle (UAV). Many commercial purposes have been investigated in recent years. Also, unmanned reconnaissance and combat aircraft attract more interest; in hazardous regions, small aircraft can be deployed to do risky, but necessary jobs. And with success. But is the idea of using UAVs in locations where human lives are at stake really that new?","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:50093246-f781-4930-881a-d91472a72ec4","http://resolver.tudelft.nl/uuid:50093246-f781-4930-881a-d91472a72ec4","A Multivariate Correlation Analysis of High- Frequency Bottom Backscattering Strength Measurements With Geotechnical Parameters","Simons, D.G.; Snellen, M.; Ainslie, M.A.","","2007","Sound backscattered from the seabed has been measured in a 10x10-nmi2 region of the North Sea, characterized by a variety of bottom types, including mud, sand, and gravel. The backscattering strength measurements are made by a forward- looking sonar, operating at 100 kHz and tilted at an angle of 30 from the horizontal. Fifty bottom-grab samples, representative of the uppermost 20 cm, were taken and analyzed for gravel content, shell content, and grain-size distribution. The backscatter measurements are correlated with the gravel percentage, shell percentage, and median grain size. A strong positive correlation of the measured backscatter strength with shell and gravel percentage is observed. Additionally, a small positive correlation between the backscatter strength and the median grain size of the sand and mud part exists. The derived values for the backscatter strength compare well to those presented in the recent literature. From a least squares curve-fitting analysis, an empirical expression is obtained giving backscatter strength as a function of gravel percentage, shell percentage, and the median grain size of the sand and mud part.","modeling; scattering; seafloor; underwater acoustic measurements","en","journal article","IEEE","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:50d8b740-e299-4d50-97b2-f9d6f3cc95e9","http://resolver.tudelft.nl/uuid:50d8b740-e299-4d50-97b2-f9d6f3cc95e9","Kepler mission; NASA's newest earth-like planet hunter","Hiddink, S.; Vromen, S.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c791f1e2-ab43-44c7-9db7-b5cb13a9dcc8","http://resolver.tudelft.nl/uuid:c791f1e2-ab43-44c7-9db7-b5cb13a9dcc8","Computation of a test statistic in data quality control","Chang, X.W.; Paige, C.C.; Tiberius, C.C.J.M.","","2005","When processing observational data, statistical testing is an essential instrument for rendering harmless incidental anomalies and disturbances in the measurements. A commonly used test statistic based on the general linear model is the generalized likelihood ratio test statistic. The standard formula given in the literature for this test statistic is not defined if the noise covariance matrix is singular, and is not suitable for computation if any of the matrices involved are ill-conditioned. Based on Paige’s generalized linear least squares method [Comm. Statist. B—Simulation Comput., 7 (1978), pp. 437–453], a numerically stable approach is proposed for the computation of the test statistic, as well as for the estimates of the parameter vectors, and reliable representations of the error covariance matrices for these estimates are presented. This approach allows the noise covariance matrix to be singular and can be applied directly to the linear model with linear equality constraints.","data quality control; statistical testing; generalized likelihood ratio; generalized least squares; generalized QR factorization; numerical stability","en","journal article","Society for Industrial and Applied Mathematics","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:6ecbc30c-227c-48bf-9572-544168e95506","http://resolver.tudelft.nl/uuid:6ecbc30c-227c-48bf-9572-544168e95506","VTOL aircraft; go up, go forward, go down","L'Ortye, J.","","2013","A large percentage of the population of the Western world has at least one experience of having flown inside a conventional (e.g. non-Vertical Take-Off and Landing) airplane, but only a small percentage of this population has ever been in a helicopter. And while airplanes dominate the aviation world, helicopters only fill small and often unseen niches. Other VTOL airplanes and machines are even less visible.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ff8a4e39-c4f1-476b-be34-e82352674ba0","http://resolver.tudelft.nl/uuid:ff8a4e39-c4f1-476b-be34-e82352674ba0","Search for life - VSV symposium 2011; an account of the wonderful symposium organised by the VSV 'Leonardo da Vinci'","Noordam, N.","","2011","On March 8th, the Search for Life symposium took place in the TU Delft Auditorium. A day full of new visions on the hunt for extraterrestrial life was programmed. The TU Delft Auditorium provided the perfect playground for the 180 attendants to exchange thoughts on this topic","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:236b5e62-408a-4612-b8e4-7a69043e3a25","http://resolver.tudelft.nl/uuid:236b5e62-408a-4612-b8e4-7a69043e3a25","Thermoelectric power in carbon nanotubes and quantum wires of nonlinear optical, optoelectronic, and related materials under strong magnetic field: Simplified theory and relative comparison","Ghatak, K.P.; Bhattacharya, S.; Bhowmik, S.; Benedictus, R.; Choudhury, S.","","2008","We study thermoelectric power under strong magnetic field (TPM) in carbon nanotubes (CNTs) and quantum wires (QWs) of nonlinear optical, optoelectronic, and related materials. The corresponding results for QWs of III-V, ternary, and quaternary compounds form a special case of our generalized analysis. The TPM has also been investigated in QWs of II-VI, IV-VI, stressed materials, n-GaP, p-PtSb2, n-GaSb, and bismuth on the basis of the appropriate carrier dispersion laws in the respective cases. It has been found, taking QWs of n-CdGeAs2, n-Cd3As2, n-InAs, n-InSb, n-GaAs, n-Hg1?xCdxTe, n-In1?xGaxAsyP1?y lattice-matched to InP, p-CdS, n-PbTe, n-PbSnTe, n-Pb1?xSnxSe, stressed n-InSb, n-GaP, p-PtSb2, n-GaSb, and bismuth as examples, that the respective TPM in the QWs of the aforementioned materials exhibits increasing quantum steps with the decreasing electron statistics with different numerical values, and the nature of the variations are totally band-structure-dependent. In CNTs, the TPM exhibits periodic oscillations with decreasing amplitudes for increasing electron statistics, and its nature is radically different as compared with the corresponding TPM of QWs since they depend exclusively on the respective band structures emphasizing the different signatures of the two entirely different one-dimensional nanostructured systems in various cases. The well-known expression of the TPM for wide gap materials has been obtained as a special case under certain limiting conditions, and this compatibility is an indirect test for our generalized formalism. In addition, we have suggested the experimental methods of determining the Einstein relation for the diffusivity-mobility ratio and the carrier contribution to the elastic constants for materials having arbitrary dispersion laws.","band structure; cadmium compounds; carbon nanotubes; gallium arsenide; gallium compounds; germanium compounds; III-V semiconductors; II-VI semiconductors; indium compounds; IV-VI semiconductors; lead compounds; mercury compounds; nonlinear optics; platinum compounds; semiconductor quantum wires; ternary semiconductors; thermoelectric power; tin compounds","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:377f3f89-3d1f-4597-aa6b-c5b0781b6705","http://resolver.tudelft.nl/uuid:377f3f89-3d1f-4597-aa6b-c5b0781b6705","Airplane adaptive structures; a passed station or a promise yet to be fulfilled?","Vos, R.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f3ec3290-2659-4dba-88df-54e27ba63310","http://resolver.tudelft.nl/uuid:f3ec3290-2659-4dba-88df-54e27ba63310","Low-cost ""care free"" cargo floor panel; an impact resistant fibre-metal laminate concept","Morinière, F.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:fba7fc54-0265-4569-a381-fad5821401a3","http://resolver.tudelft.nl/uuid:fba7fc54-0265-4569-a381-fad5821401a3","Automating wiring formboard design","Van den Berg, T.","","2013","Increase in aircraft wiring complexity call for manufacturing design improvements to reduce cost and lead-time. To achieve such improvements, a joint research project was performed by the Flight Performance and Propulsion (FPP) group and Fokker Elmo BV, the second largest aircraft wiring harness manufacturer in the world. The project objective was to largely automate the creation of manufacturing drawings using Knowledge Based Engineering techniques.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:446f5f5d-2e25-41fb-b6c4-4f0acd36d026","http://resolver.tudelft.nl/uuid:446f5f5d-2e25-41fb-b6c4-4f0acd36d026","Space shuttle: Icon of space exploration; a brief history about a unique program that enabled many advances in science and technology","Van Dijk, E.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5d5889cf-a4de-4594-bc8b-188416654701","http://resolver.tudelft.nl/uuid:5d5889cf-a4de-4594-bc8b-188416654701","Performance evaluation of automated approaches to building detection in multi-source aerial data","Khoshelham, K.; Nardinocchi, C.; Frontoni, C.; Mancini, A.; Zingaretti, P.","","2009","Automated approaches to building detection in multi-source aerial data are important in many applications, including map updating, city modeling, urban growth analysis and monitoring of informal settlements. This paper presents a comparative analysis of different methods for automated building detection in aerial images and laser data at different spatial resolutions. Five methods are tested in two study areas using features extracted at both pixel level and object level, but with the strong prerequisite of using the same training set for all methods. The evaluation of the methods is based on error measures obtained by superimposing the results on a manually generated reference map of each area. The results in both study areas show a better performance of the Dempster-Shafer and the AdaBoost methods, although these two methods also yield a number of unclassified pixels. The method of thresholding a normalized DSM performs well in terms of the detection rate and reliability in the less vegetated Mannheim study area, but also yields a high rate of false positive errors. The Bayesian methods perform better in the Memmingen study area where buildings have more or less the same heights.","building detection; automation; classification; LiDAR; map updating; OA-Fund TU Delft","en","journal article","Elsevier","","","","","","","","Aerospace Engineering","","","","",""
"uuid:62ba8d34-b861-451a-90ba-9d8e453d2889","http://resolver.tudelft.nl/uuid:62ba8d34-b861-451a-90ba-9d8e453d2889","Assessment of Relative Accuracy of AHN-2 Laser Scanning Data Using Planar Features","Khoshelham, K.; Soudarissanane, S.; Van der Sande, C.","","2010","AHN-2 is the second part of the Actueel Hoogtebestand Nederland project, which concerns the acquisition of high-resolution altimetry data over the entire Netherlands using airborne laser scanning. The accuracy assessment of laser altimetry data usually relies on comparing corresponding tie elements, often points or lines, in the overlapping strips. This paper proposes a new approach to strip adjustment and accuracy assessment of AHN-2 data by using planar features. In the proposed approach a transformation is estimated between two overlapping strips by minimizing the distances between points in one strip and their corresponding planes in the other. The planes and the corresponding points are extracted in an automated segmentation process. The point-to-plane distances are used as observables in an estimation model, whereby the parameters of a transformation between the two strips and their associated quality measures are estimated. We demonstrate the performance of the method for the accuracy assessment of the AHN-2 dataset over Zeeland province of The Netherlands. The results show vertical offsets of up to 4 cm between the overlapping strips, and horizontal offsets ranging from 2 cm to 34 cm.","altimetry; accuracy assessment; Airborne Laser Scanning; OA-Fund TU Delft","en","journal article","MDPI","","","","","","","","Aerospace Engineering","Optical and Laser Remote Sensing","","","",""
"uuid:c87eeaef-8dd8-45ab-827c-0506ea7d13c3","http://resolver.tudelft.nl/uuid:c87eeaef-8dd8-45ab-827c-0506ea7d13c3","Project Stratos; reaching space with a student-built rocket","Haneveer, M.","","2013","In the spring of 2009 a team of 15 TU Delft students travelled to Kiruna, Sweden with only one goal: to launch the rocket Stratos I they had been working on for 2 years to an altitude of over 12km, thereby claiming the European Amateur Rocket Altitude record. These students were part of Delft Aerospace Rocket Engineering (DARE), a Dream Team of the TU Delft involved in research, development, manufacturing and launching of rockets. However, this record-breaking launch was not a single project; it was the first part of a larger endeavour of which the primary goal was to become the first student team in the world to reach space with a student-built rocket.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:df73fd87-7aee-4523-92e7-766130dc5e4e","http://resolver.tudelft.nl/uuid:df73fd87-7aee-4523-92e7-766130dc5e4e","Investigation of the flow in a circular cavity using stereo and tomographic particle image velocimetry","Haigermoser, C.A.H.K.; Scarano, F.; Onorato, M.","","2008","","","en","journal article","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ee4028c2-ddbc-40e2-a0df-8cb7e68f3c5d","http://resolver.tudelft.nl/uuid:ee4028c2-ddbc-40e2-a0df-8cb7e68f3c5d","On the nature of GPS draconitic year periodic pattern in multivariate position time series","Amiri-Simkooei, A.R.","","2013","Plate tectonics studies using GPS require proper analysis of time series, in which all functional effects are understood and all stochastic effects are captured using an appropriate noise assessment technique. Both issues are addressed in this contribution. Estimates of spatial correlation, time correlated noise, and multivariate power spectrum for daily position time series of 350, 150, and 50 permanent GPS stations, respectively, collected between 2000–2007, 1998–2007, and 1996–2007 are obtained. The daily GPS global solutions were processed by the GPS Analysis Center at JPL. The detection power of the common-mode signals is improved by including the time- and space-correlated noise into the least squares power spectrum. Previous signals, such as those with periods of 13.63, 14.2, 14.6, and 14.8?days, are identified in the multivariate analysis. Significant signal with period of 351.6?±?0.2?days and its higher harmonics are detected in the series, which closely follows the GPS draconitic year. The variation range of this periodic pattern for the north, east, and up components are about ±3, ±3.2, and ±6.5?mm, respectively. Three independent criteria confirm that this periodic pattern is of similar nature at adjacent stations, indicating its independence of the station-related effects such as multipath. It is likely due to the other causes of the GPS draconitic year period driven into GPS time series. The multivariate power spectrum shows a cluster of signals with periods ranging from 5 to 6?days (quasiperiodic signals). In their aliased forms, the effects are likely partly responsible for the time-correlated noise and partly for the periodic patterns at lower frequencies.","permanent GPS station velocity; temporal and spatial correlation; GPS draconitic year period; multivariate harmonic estimation","en","journal article","American Geophysical Union","","","","","","","2013-11-22","Aerospace Engineering","Control & Operations","","","",""
"uuid:e979ebcc-6edf-4e32-a27c-57e0ac432954","http://resolver.tudelft.nl/uuid:e979ebcc-6edf-4e32-a27c-57e0ac432954","Lunar tide contribution to thermosphere weather","Zhang, J.T.; Forbes, J.M.; Zhang, C.H.; Doornbos, E.N.; Bruinsma, S.L.","","2014","As the utilization of low-Earth orbit increases, so does the need for improved ephemeris predictions and thus more accurate density models. In this paper we quantify the density variability of the thermosphere attributable to the lunar gravitational tide, a potentially predictable component of variability not included in any operational density prediction models to date. Using accelerometer measurements from the GOCE satellite near 260 km altitude, the level of lunar tidal density variability is shown to be about half that associated with the low level of geomagnetic variability that occurs about 75% of the time (Kp ? 3), thus constituting an element of “space weather.” Our conclusion is that the lunar tide ought to be considered for inclusion in contemporary density models of the thermosphere for operational ephemeris predictions. Some suggested first steps are included in the conclusions of this paper.","lunar tide; thermosphere weather; GOCE","en","journal article","American Geophysical Union","","","","","","","2015-03-01","Aerospace Engineering","Space Engineering","","","",""
"uuid:aee60408-a6e6-4a78-87bd-8b5f5105b5c2","http://resolver.tudelft.nl/uuid:aee60408-a6e6-4a78-87bd-8b5f5105b5c2","High speed PIV applied to aerodynamic noise investigation","Koschatzky, V.; Moore, P.D.; Westerweel, J.; Scarano, F.; Boersma, B.J.","","2010","In this paper, we study the acoustic emissions of the flow over a rectangular cavity. Especially, we investigate the possibility of estimating the acoustic emission by analysis of PIV data. Such a possibility is appealing, since it would allow to directly relate the flow behavior to the aerodynamic noise production. This will help considerably in understanding the noise production mechanisms and to investigate the possible ways of reducing it. In this study, we consider an open cavity with an aspect ratio between its length and depth of 2 at a Reynolds number of 2.4 9 104 and 3.0 9 104 based on the cavity length. The study is carried out combining high speed two-dimensional PIV, wall pressure measurements and sound measurements. The pressure field is computed from the PIV data. Curle’s analogy is applied to obtain the acoustic pressure field. The pressure measurements on the wall of the cavity and the sound measurements are then used to validate the results obtained from PIV and check the range of validity of this approach. This study demonstrated that the technique is able to quantify the acoustic emissions from the cavity and is promising especially for capturing the tonal components on the sound emission.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:e8a9a859-845e-4e74-ba30-2b24535fb1e4","http://resolver.tudelft.nl/uuid:e8a9a859-845e-4e74-ba30-2b24535fb1e4","Losing your spaceflight virginity","Motsyk, O.","","2012","Sir Richard Branson drops by The Hague to pick up ISTA Award and discuss the future of Virgin Galactic","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b66a0d9c-1e59-4706-9a08-61818dfcd263","http://resolver.tudelft.nl/uuid:b66a0d9c-1e59-4706-9a08-61818dfcd263","Spectral harmonic analysis and synthesis of Earth’s crust gravity field","Tenzer, R.; Novák, P.; Vajda, P.; Gladkikh, V.; Hamayun, K.","","2011","We developed and applied a novel numerical scheme for a gravimetric forward modelling of the Earth’s crustal density structures based entirely on methods for a spherical analysis and synthesis of the gravitational field. This numerical scheme utilises expressions for the gravitational potentials and their radial derivatives generated by the homogeneous or laterally varying mass density layers with a variable height/depth and thickness given in terms of spherical harmonics. We used these expressions to compute globally the complete crust-corrected Earth’s gravity field and its contribution generated by the Earth’s crust. The gravimetric forward modelling of large known mass density structures within the Earth’s crust is realised by using global models of the Earth’s gravity field (EGM2008), topography/bathymetry (DTM2006.0), continental ice-thickness (ICE-5G), and crustal density structures (CRUST2.0). The crust-corrected gravity field is obtained after modelling and subtracting the gravitational contribution of the Earth’s crust from the EGM2008 gravity data. These refined gravity data mainly comprise information on the Moho interface and mantle lithosphere. Numerical results also reveal that the gravitational contribution of the Earth’s crust varies globally from 1,843 to 12,010 mGal. This gravitational signal is strongly correlated with the crustal thickness with its maxima in mountainous regions (Himalayas, Tibetan Plateau and Andes) with the presence of large isostatic compensation. The corresponding minima over the open oceans are due to the thin and heavier oceanic crust.","crust; forward modelling; gravity field; spectral representation; synthetic model of the earth","en","journal article","Springer","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:e2f1c2de-5ef0-408b-b319-a9f2b6fa95c0","http://resolver.tudelft.nl/uuid:e2f1c2de-5ef0-408b-b319-a9f2b6fa95c0","Prandtl's best wing system; minimizing induced drag","Pruijsers, T.","","2013","Innovation in the ""eld of Aerospace Engineering is driven by the need for more sustainable aircraft with lower emissions, lower operating costs and lower noise pollution: ‘sustainable growth’. These goals for the future have never been more relevant than now with the weak economy, global warming and the ever-growing need for air travel. That is why engineers are beginning to look for unconventional solutions for the future of aviation.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e9b5e8a5-e327-4fdd-9da2-7f1644af900d","http://resolver.tudelft.nl/uuid:e9b5e8a5-e327-4fdd-9da2-7f1644af900d","Galileo: ESA's greatest endeavor; the embodiment of Europe's choise to remain a world-power","Beeftink, D.","","2011","Galileo is a global satellite navigation system that is being built at the initiative of the European Space Agency (ESA) and the European Union (EU). It is going to be Europe's own independent satellite system, invulnerable to ill-willing foreign governments. This ambitious project is part of Europe's plan to stay an important player in the world's politics","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:30f50d81-b8a2-4aa8-a031-807019c47819","http://resolver.tudelft.nl/uuid:30f50d81-b8a2-4aa8-a031-807019c47819","Stealth: The art of invisibility - the future is bright, the future is stealth","Jansen, R.; Breur, J.","","2011","The philosophy of stealth is simple: if they cannot see you, the cannot attack you. This starts with basic things such as a camouflage painting and noise reduction. Stealth technology takes 'not being seen' to the next level with radar absorbing materials, complicated shapes and reduced heat emission. All this to remain hidden from the enemy","stealth","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3a7da449-9d02-4d99-bd25-bdbafb4f846e","http://resolver.tudelft.nl/uuid:3a7da449-9d02-4d99-bd25-bdbafb4f846e","Study tour 2011 'Orient'; discovering the secrets of the Oriental Aerospace Insdustry","Soepnel, S.; Biersteker, S.; Frans, D.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3f9194dc-95ba-4799-8feb-2edfc3e8d512","http://resolver.tudelft.nl/uuid:3f9194dc-95ba-4799-8feb-2edfc3e8d512","Infrasonic interferometry of stratospherically refracted microbaroms: A numerical study","Fricke, J.T.; El Allouche, N.; Simons, D.G.; Ruigrok, E.N.; Wapenaar, C.P.A.; Evers, L.G.","","2013","The atmospheric wind and temperature can be estimated through the traveltimes of infrasound between pairs of receivers. The traveltimes can be obtained by infrasonic interferometry. In this study, the theory of infrasonic interferometry is verified and applied to modeled stratospherically refracted waves. Synthetic barograms are generated using a raytracing model and taking into account atmospheric attenuation, geometrical spreading, and phase shifts due to caustics. Two types of source wavelets are implemented for the experiments: blast waves and microbaroms. In both numerical experiments, the traveltimes between the receivers are accurately retrieved by applying interferometry to the synthetic barograms. It is shown that microbaroms can be used in practice to obtain the traveltimes of infrasound through the stratosphere, which forms the basis for retrieving the wind and temperature profiles.","","en","journal article","Acoustical Society of America","","","","","","","2014-04-01","Aerospace Engineering","Control & Operations","","","",""
"uuid:64d48532-5de8-494d-ae81-347d55b296cd","http://resolver.tudelft.nl/uuid:64d48532-5de8-494d-ae81-347d55b296cd","magnet assisted take-off; an innovative way of taking to the skies","Wu, P.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:41ed5a9d-f8f0-4e77-8774-36a1a5256327","http://resolver.tudelft.nl/uuid:41ed5a9d-f8f0-4e77-8774-36a1a5256327","Frequency-dependent data weighting in global gravity field modeling from satellite data contaminated by non-stationary noise","Ditmar, P.; Klees, R.; Liu, X.","","2007","","Earth's gravity field; Colored noise; Covariance matrix estimation; CHAMP (CHAllenging Mini-satellite Payload); Satellite-borne accelerometer","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:77aaf94f-0aba-4848-b15a-a1404cd66cde","http://resolver.tudelft.nl/uuid:77aaf94f-0aba-4848-b15a-a1404cd66cde","Design of an Airborne Three-Dimensional Separation Assistance Display","Ellerbroek, J.; Visser, M.; Van Dam, S.B.J.; Van Paassen, M.M.; Mulder, M.","","2011","In the context of the Next Generation Air Transportation System and Single European Sky ATM Research future airspace programs, this paper describes a concept for an airborne separation assurance display that is designed to aid pilots in their task of self-separation, by visualizing the possibilities for conflict resolution that the airspace provides. This paper is part of an ongoing research toward an ecological design of a separation assistance interface that can present all the relevant properties of the spatiotemporal separation problem. A work-domain analysis is described from which several perspective projections of traffic properties and travel constraints are derived. A display concept is proposed that presents heading and altitude action possibilities in a flight-path angle-track angle action space. Key issues in the current design are discussed, with recommendations for future work.","Ecological Interface Design (EID); Airborne Separation Assistance System (ASAS); self-separation; situation awareness","en","journal article","IEEE","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:c5610452-57c0-45b8-a603-8a20929d2391","http://resolver.tudelft.nl/uuid:c5610452-57c0-45b8-a603-8a20929d2391","Trash bands; space debris as main threat to space missions","Van Zeeland, J.; Blank, B.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:cd6fe4c6-c420-4e88-b711-efd5d86714db","http://resolver.tudelft.nl/uuid:cd6fe4c6-c420-4e88-b711-efd5d86714db","Three-dimensional vortex analysis and aeroacoustic source characterization of jet core breakdown","Violato, D.; Scarano, F.","","2013","The three-dimensional behavior of jet core breakdown is investigated with experiments conducted on a free water jet at Re = 5000 by time-resolved tomographic particle image velocimetry (TR-TOMO PIV). The investigated domain encompasses the range between 0 and 10 jet diameters. The characteristic pulsatile motion of vortex ring shedding and pairing culminates with the growth of four primary in-plane and out-of-plane azimuthal waves and leads to the formation of streamwise vortices. Vortex ring humps are tilted and ejected along the axial direction as they are subjected to higher axial velocities. By the end of the potential core, this process causes the breakdown of the vortex ring regime and the onset of streamwise filaments oriented at 30°-45° to the jet axis and “C” shaped peripheral structures. The latter re-organize further downstream in filaments oriented along the azimuthal direction at the jet periphery. Instead, in the vicinity of the jet axis the filaments do not exhibit any preferential direction resembling the isotropic turbulent regime. Following Powell's aeroacoustic analogy, the instantaneous spatial distribution of the acoustic source term is mapped by the second time derivative of the Lamb vector, revealing the highest activity during vortex ring breakdown. A three-dimensional modal analysis of velocity, vorticity, Lamb vector, and Lamb vector second time derivative fields is conducted by proper orthogonal decomposition (POD) within the first 10 modes. The decomposed velocity fluctuations describe a helical organization in the region of the jet core-breakdown and, further downstream, jet axis flapping and precession motions. By the end of the potential core, vorticity modes show that vortex rings are dominated by travelling waves of radial and axial vorticity with a characteristic 40°-45° inclination to the jet axis. The Lamb vector and the Lamb vector second time derivative modes exhibit similar patterns for the azimuthal component, whereas the vortex ring coherence is described by the radial and the axial components. While velocity, vorticity, and Lamb vector modes are typically associated with Strouhal numbers (St) smaller than 0.9, the modes of the Lamb vector second time derivative are also related to higher frequencies (1.05 ? St ? 1.9) ascribed to the three-dimensional travelling waves. Far-field acoustic predictions are obtained on the basis of direct evaluation of Powell's analogy with TR-TOMO PIV data. The spectral analysis returns peaks at pairing (St = 0.36) and shedding (St = 0.72) frequency. A broader distribution with a hump between St = 1 and 2.25 is observed, which corresponds to the breakdown of ring vortices.","aeroacoustics; flow visualisation; jets; pulsatile flow; turbulence; vortices; water waves","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:ee2bb6ab-4df0-4e80-b341-0e4586e1db9a","http://resolver.tudelft.nl/uuid:ee2bb6ab-4df0-4e80-b341-0e4586e1db9a","The history of the airport; from grass fields to giant cities","Peterse, H.","","2011","In the early days of aviation airports where nothing more than a simple grass field from which airplanes could take off. These days there are airports that are enormous in size, and fulfil many more functions than simply allowing aircraft to take-off and land. The airport has shown a remarkable revolution","airports","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9c95a48e-59ca-410a-978f-8d33cad2483b","http://resolver.tudelft.nl/uuid:9c95a48e-59ca-410a-978f-8d33cad2483b","A generic tool for cost estimating in aircraft design","Castagne, S.; Curran, R.; Rothwell, A.; Price, M.; Benard, E.; Raghunathan, S.","","2008","A methodology to estimate the cost implications of design decisions by integrating cost as a design parameter at an early design stage is presented. The model is developed on a hierarchical basis, the manufacturing cost of aircraft fuselage panels being analysed in this paper. The manufacturing cost modelling is original and relies on a genetic-causal method where the drivers of each element of cost are identified relative to the process capability. The cost model is then extended to life cycle costing by computing the Direct Operating Cost as a function of acquisition cost and fuel burn, and coupled with a semi-empirical numerical analysis using Engineering Sciences Data Unit reference data to model the structural integrity of the fuselage shell with regard to material failure and various modes of buckling. The main finding of the paper is that the traditional minimum weight condition is a dated and sub-optimal approach to airframe structural design.","Cost modelling; Manufacturing cost; Life cycle cost; Airframe design; Optimisation","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Structures","","","",""
"uuid:36323da7-6bd1-4385-ba94-e84c9c14d548","http://resolver.tudelft.nl/uuid:36323da7-6bd1-4385-ba94-e84c9c14d548","Comeback of the dreamliner; multiple layer protection for 787 battery systems","Hosseini, S.","","2013","In April of this year the Federal Aviation Administration approved the new battery systems of the 787-8 Dreamliner, and after having been grounded for three months, the aircraft were cleared for take-off. Boeing dealt with serious problems when complications occurred with the batteries of the 787. Looking back, Boeing did not only solve the problems it was facing, but the aviation company took an additional step and announced the final assembly of the 787-9 Dreamliner.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b323692a-7356-4416-995f-b3596e5a2c8c","http://resolver.tudelft.nl/uuid:b323692a-7356-4416-995f-b3596e5a2c8c","Phase discontinuity predictions using a machine-learning trained kernel","Sawaf, F.; Groves, R.M.","","2014","Phase unwrapping is one of the key steps of interferogram analysis, and its accuracy relies primarily on the correct identification of phase discontinuities. This can be especially challenging for inherently noisy phase fields, such as those produced through shearography and other speckle-based interferometry techniques. We showed in a recent work how a relatively small 10×10 pixel kernel was trained, through machine learning methods, for predicting the locations of phase discontinuities within noisy wrapped phase maps. We describe here how this kernel can be applied in a sliding-window fashion, such that each pixel undergoes 100 phase-discontinuity examinations—one test for each of its possible positions relative to its neighbors within the kernel’s extent. We explore how the resulting predictions can be accumulated, and aggregated through a voting system, and demonstrate that the reliability of this method outperforms processing the image by segmenting it into more conventional 10×10 nonoverlapping tiles. When used in this way, we demonstrate that our 10×10 pixel kernel is large enough for effective processing of full-field interferograms. Avoiding, thus, the need for substantially more formidable computational resources which otherwise would have been necessary for training a kernel of a significantly larger size.","phase unwrapping; pattern recognition, neural networks; speckle interferometry, metrology; fringe analysis; nondestructive testing","en","journal article","Optical Society of America","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:9c0f1a16-84fb-4f6d-ba81-2ba226dcbde4","http://resolver.tudelft.nl/uuid:9c0f1a16-84fb-4f6d-ba81-2ba226dcbde4","Quality control in SBAS: Protection levels and reliability levels","Oliveira, J.M.V.; Tiberius, C.C.J.M.","","2009","This contribution extends the common documented approach of integrity through Protection Levels in Satellite-Based Augmentation System (SBAS) positioning for aeronautics, to reliability on the basis of statistical hypothesis testing, and as such provides a safeguard against model misspecifications as anomalies and outliers in the measurements. It is shown that when integrity is monitored through Protection Levels and reliability added through Reliability Levels, the availability of the SBAS position solution is more than 99% for APV-I precision approach. The availability for CAT-I is currently just a few percent. When the Galileo constellation is added, and current performance is copied ahead, the percentage for CAT-I increases to beyond 95%.","SBAS; integrity; reliability level","en","journal article","Cambridge University Press","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:6dd761b5-ab0f-4248-94bb-22c74d986ff2","http://resolver.tudelft.nl/uuid:6dd761b5-ab0f-4248-94bb-22c74d986ff2","Design of a recurve actuator for maximum energy efficiency","Seresta, O.; Ragon, S.; Abdalla, M.M.; Gürdal, Z.; Lindner, D.K.","","2006","","","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b787debd-6a83-4314-8cd6-a7d14fbc653b","http://resolver.tudelft.nl/uuid:b787debd-6a83-4314-8cd6-a7d14fbc653b","Molecular ordering in the high-temperature nematic phase of an all-aromatic liquid crystal","Vita, F.; Hegde, M.; Portale, G.; Bras, W.; Ferrero, C.; Samulski, E.T.; Francescangeli, O.; Dingemans, T.","","2016","We report the structural characterization of the nematic phase of 2,6-biphenyl naphthalene (PPNPP). This lath-like all-aromatic mesogen provides a valuable benchmark for classical theories of nematic order. PPNPP exhibits a very high temperature nematic phase (417–489 °C) above an enantiotropic smectic A phase. X-ray diffraction reveals a surprisingly strong tendency towards molecular layering in the nematic phase, indicative of “normal cybotaxis” (i.e. SmA-like stratification within clusters of mesogens). Although stronger at low temperatures, the layering is evident well above the smectic A-nematic transition. The nematic order parameter is evaluated as a function of temperature from the broadening of the wide-angle diffuse diffraction feature. Measured values of the orientational order parameter are slightly larger than those predicted by the Maier–Saupe theory over the entire nematic range except for a narrow region just below the clearing point where they significantly drop below the theoretical prediction.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:f2b6bdbd-5d11-4ec5-ac7e-d2c2ce21144c","http://resolver.tudelft.nl/uuid:f2b6bdbd-5d11-4ec5-ac7e-d2c2ce21144c","A new approach to linear regression with multivariate splines","De Visser, C.C.; Chu, Q.P.; Mulder, J.A.","","2009","A new methodology for creating highly accurate, static nonlinear maps from scattered, multivariate data is presented. This new methodology uses the B-form polynomials of multivariate simplex splines in a new linear regression scheme. This allows the use of standard parameter estimation techniques for estimating the B-coefficients of the multivariate simplex splines. We present a generalized least squares estimator for the B-coefficients, and show how the estimated B-coefficient variances lead to a new model quality assessment measure in the form of the B-coefficient variance surface. The new modeling methodology is demonstrated on a nonlinear scattered bivariate dataset.","splines; parameter estimation; scattered data; multivariate splines","en","journal article","Elsevier","","","","","","","2014-05-01","Aerospace Engineering","Control & Operations","","","",""
"uuid:261e7eca-e195-4de0-a6e5-17b1377af0e9","http://resolver.tudelft.nl/uuid:261e7eca-e195-4de0-a6e5-17b1377af0e9","How to handle colored observation noise in large least-squares problems","Klees, R.; Ditmar, P.; Broersen, P.","","2003","An approach to handling colored observation noise in large least-squares (LS) problems is presented. The handling of colored noise is reduced to the problem of solving a Toeplitz system of linear equations. The colored noise is represented as an auto regressive moving-average (ARMA) process. Stability and invertability of the ARMA model allows the solution of the Toeplitz system to be reduced to two successive filtering operations using the inverse transfer function of the ARMA model. The numerical complexity of the algorithm scales proportionally to the order of the ARMA model times the number of observations. This makes the algorithm particularly suited for LS problems with millions of observations. It can be used in combination with direct and iterative algorithms for the solution of the normal equations. The performance of the algorithm is demonstrated for the computation of a model of the Earth’s gravity field from simulated satellite-derived gravity gradients up to spherical harmonic degree 300.","large least-squares problems; auto regressive moving-average process; noise power spectral density function; satellite gravity gradiometry","en","journal article","Springer","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:e1335360-7eff-43b5-be32-ff9e7331f397","http://resolver.tudelft.nl/uuid:e1335360-7eff-43b5-be32-ff9e7331f397","From concept to certification; interview with AD&C co-founder and CEO Marcus Basien","L'Ortye, J.; Spranger, L.","","2013","Before any aircraft concept takes to the sky, air travel authorities require the aircraft be certified. One would expect a big organisation like EASA would function like a centralised verification authority. However, small companies like Aircraft Design & Certification Ltd. offer certification services for general aviation aircraft. Leonardo Times sat down with AD&C co-founder Marcus Basien to discuss the process of certification, future developments of the industry and possibilities for Aerospace Engineering students.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:379dd556-d21b-4c29-9f16-281573b9ec47","http://resolver.tudelft.nl/uuid:379dd556-d21b-4c29-9f16-281573b9ec47","Tomographic-PIV measurement of the flow around a zigzag boundary layer trip","Elsinga, G.E.; Westerweel, J.","","2012","Tomographic-PIV was used to measure the boundary layer transition forced by a zigzag trip. The resulting instantaneous three-dimensional velocity distributions are used to quantitatively visualize the flow structures. They reveal undulating spanwise vortices directly behind the trip, which break up into individual arches and then develop into the hairpin-like structures typical of wallbounded turbulence. Compared to the instantaneous flow structure, the structure of the average velocity field is very different showing streamwise vortices. Such streamwise vortices are often associated with the low-speed streaks occurring in bypass transition flows, but in this case clearly are an artifact of the averaging. Rather, the present streaks in the separated flow region directly behind the trip are resulting from the waviness in the spanwise vortices as introduced by the zigzag trip. Furthermore, these streaks and the separated flow region are observed to be related to a large-scale, spanwise uniform unsteadiness in the flow that contributes significantly to the velocity fluctuations over large downstream distances (up to at least the edge of the present measurement domain).","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8fcffd8f-f6d1-442b-83d9-27b794c8c2cd","http://resolver.tudelft.nl/uuid:8fcffd8f-f6d1-442b-83d9-27b794c8c2cd","Numerical Investigation on the Propulsive Performance of Biplane Counter-flapping Wings","Deng, S.; Xiao, T.; Van Oudheusden, B.W.; Bijl, H.","","2015","A numerical investigation is performed to address the flexing effect on the propulsion performance of flapping wing particularly on the counter-flapping wings of the biplane configuration. A Reynolds number of 10,000 is considered in the present study which corresponds to the flight regime of most existing flapping wing micro air vehicles. The computation involves solving the compressible unsteady Reynolds- averaged Native-Stokes equation using an inhouse developed code. The flapping motion is incorporated by an efficient deforming overset grid technique which allows multiple flexible bodies to be embedded into the flow field. Results show that the biplane wing with counter-flapping configuration has a better propulsive performance in comparison to a single flapping wing. A low-pressure regime between the two wings during the outstroke produces more thrust, while the counter-flapping motion can also generate a surfeit momentum rushing in to the wake. The more flexible wing can produce more thrust while less power is required thus owning a better propulsive performance.","","en","journal article","Multi-Science Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:e070de9d-e805-4aa5-9bcc-7f8719bb56e1","http://resolver.tudelft.nl/uuid:e070de9d-e805-4aa5-9bcc-7f8719bb56e1","A novel adaptive kernel method with kernel centers determined by a support vector regression approach","Sun, L.G.; De Visser, C.C.; Chu, Q.P.; Mulder, J.A.","","2012","The optimality of the kernel number and kernel centers plays a significant role in determining the approximation power of nearly all kernel methods. However, the process of choosing optimal kernels is always formulated as a global optimization task, which is hard to accomplish. Recently, an algorithm, namely improved recursive reduced least squares support vector regression (IRR-LSSVR), was proposed for establishing a global nonparametric offline model, which demonstrates significant advantage in choosing representing and fewer support vectors compared with others. Inspired by the IRR- LSSVR, a new adaptive parametric kernel method called WV-LSSVR is proposed in this paper using the same type of kernels and the same centers as those used in the IRR-LSSVR. Furthermore, inspired by the multikernel semiparametric support vector regression, the effect of the kernel extension is investigated in a recursive regression framework, and a recursive kernel method called GPK-LSSVR is proposed using a compound type of kernels which are recommended for Gaussian process regression. Numerical experiments on benchmark data sets confirm the validity and effectiveness of the presented algorithms. The WV-LSSVR algorithm shows higher approximation accuracy than the recursive parametric kernel method using the centers calculated by the k-means clustering approach. The extended recursive kernel method (i.e. GPK-LSSVR) has not shown advantage in terms of global approximation accuracy when validating the test data set without real-time updation, but it can increase modeling accuracy if the real-time identification is involved.","support vector machine; recursive identification; adaptive model; kernel basis function","en","journal article","Elsevier","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:c6216680-d7b2-47a2-b734-1747c686f69e","http://resolver.tudelft.nl/uuid:c6216680-d7b2-47a2-b734-1747c686f69e","A scaling analysis for turbulent shock-wave/boundary-layer interactions","Souverein, L.J.; Bakker, P.G.; Dupont, P.","","2013","A model based on mass conservation properties is developed for shock-wave/boundarylayer interactions (SWBLIs), aimed at reconciling the observed great diversity in flow organization documented in the literature, induced by variations in interaction geometry and aerodynamic conditions. It is the basis for a scaling approach for the interaction length that is valid independent of the geometry of the flow (considering compression corners and incident-reflecting shock interactions). As part of the analysis, a scaling argument is proposed for the imposed pressure jump that depends principally on the free-stream Mach number and the flow deflection angle. Its interpretation as a separation criterion leads to a successful classification of the separation states for turbulent SWBLIs (attached, incipient or separated). In addition, the dependence of the interaction length on the Reynolds number and the Mach numbers is accounted for. A large compilation of available data provides support for the validity of the model. Some general properties on the state of the flow are derived, independent of the geometry of the flow and for a wide range of Mach numbers and Reynolds numbers.","compressible boundary layers; compressible flows; shock waves","en","journal article","Cambridge University Press","","","","","","","2014-01-02","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:ed023b88-02e7-4ed6-96bb-772e3dae3bd6","http://resolver.tudelft.nl/uuid:ed023b88-02e7-4ed6-96bb-772e3dae3bd6","Principles and application of velocimetry-based planar pressure imaging in compressible flows with shocks","Van Oudheusden, B.W.","","2008","","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5e7585ee-191f-4ac8-a74b-e26a92faed60","http://resolver.tudelft.nl/uuid:5e7585ee-191f-4ac8-a74b-e26a92faed60","Superbus: Using aerospace technology to make high speed transport more sustainable","Melkert, J.A.","","2007","","Superbus","en","journal article","ETC","","","","","","","","Aerospace Engineering","","","","",""
"uuid:75e67114-4230-4333-a087-4ac1648c242b","http://resolver.tudelft.nl/uuid:75e67114-4230-4333-a087-4ac1648c242b","Design synthesis exercise 2010","Melkert, J.A.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:bb9fbd28-1afd-45fe-a321-4b36b96d803b","http://resolver.tudelft.nl/uuid:bb9fbd28-1afd-45fe-a321-4b36b96d803b","Long-term sea level change in the Malaysian seas from multi-mission altimetry data","Din, A.H.; Omar, K.M.; Naeije, M.C.; Ses, S.","","2012","The long-term sea level change during 1993 to 2008 was investigated in the Malaysian seas from satellite altimetry data of the TOPEX, JASON-1, ERS-1, ERS-2 and ENVISAT missions. Sea level data retrieval and reduction were carried out using the radar altimeter database system (RADS). In RADS data processing, the 2008 updated environmental and geophysical corrections were applied. Six 1° × 1° areas were chosen for the altimetry data comparison and to find the best ocean tide model for the Malaysian seas, where the altimeter tracks are nearby tide gauge locations. Similarity in the patterns of sea level variations indicates good agreement between tide gauge and altimetry data when using the FES2004 ocean tide model. It also shows that altimetry data is perfectly suited to investigate long-term sea level change in the Malaysian seas. Here, sea level variations for four areas in the Malaysian seas have been investigated using 15 years of altimetry data. The altimeter sea level time series revealed that since 1993, the mean sea level in Malaysian seas has been rising at a geographically-dependent rate varying from 1.4 to 4.1 mm/yr. This kind of information is important for studying environmental issues related to flood investigations and global warming especially for an area that until now have not gotten much attention from the altimeter science community.","sea level change; multi-mission altimetry; ocean tides; tide gauges","en","journal article","Academic Journals","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:98d2d7be-3275-4269-b372-48d2c20f64eb","http://resolver.tudelft.nl/uuid:98d2d7be-3275-4269-b372-48d2c20f64eb","Role Identification of Yaw and Sway Motion in Helicopter Yaw Control Tasks","Ellerbroek, J.; Stroosma, O.; Van Paassen, M.M.; Mulder, M.","","2008","A set of experiments has been conducted to investigate the relative effect of translational and rotational motion cues on pilot performance. Two helicopter yaw control tasks were performed on the SIMONA: a yaw capture task and a target-tracking task with simulated turbulence. The yaw capture task was a repetition of a task performed previously at two different simulator facilities. Shaping filters and added delays were used to match simulator characteristics with the previous experiments. In contrast to previous conclusions, results from the current study show more equal contributions of yaw and sway motion on performance and subjective simulator motion fidelity. Analyses of the different vestibular cues using multiloop pilot models, estimated from measurement data from the target-tracking task, also indicate comparable utilization of the yaw and sway motion cues.","human control behavior","en","journal article","AIAA","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:bfee6a5b-9cdd-4c28-b442-1573cac01e6e","http://resolver.tudelft.nl/uuid:bfee6a5b-9cdd-4c28-b442-1573cac01e6e","Process-time Optimization of Vacuum Degassing Using a Genetic Alloy Design Approach","Dilner, D.; Lu, Q.; Mao, H.; Xu, W.; Van der Zwaag, S.; Selleby, M.","","2014","This paper demonstrates the use of a new model consisting of a genetic algorithm in combination with thermodynamic calculations and analytical process models to minimize the processing time during a vacuum degassing treatment of liquid steel. The model sets multiple simultaneous targets for final S, N, O, Si and Al levels and uses the total slag mass, the slag composition, the steel composition and the start temperature as optimization variables. The predicted optimal conditions agree well with industrial practice. For those conditions leading to the shortest process time the target compositions for S, N and O are reached almost simultaneously.","genetic algorithm; computational thermodynamics; vacuum degassing; materials by design; steelmaking; OA-Fund TU Delft","en","journal article","MDPI","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:bde32d11-f796-40cf-9b94-48ca7068961b","http://resolver.tudelft.nl/uuid:bde32d11-f796-40cf-9b94-48ca7068961b","Into the central 10 pc of the most distant known radio quasar","Frey, S.; Paragi, Z.; Gurvits, L.I.; Gabányi, K.É.; Cseh, D.","","2011","There are about 60 quasars known at redshifts z > 5.7 to date. Only three of them are detected in the radio above 1 mJy flux density at 1.4 GHz frequency. Among them, J1429+5447 (z = 6.21) is the highest-redshift radio quasar known at present. These rare, distant, and powerful objects provide important insight into the activity of the supermassive black holes in the Universe at early cosmological epochs and into the physical conditions of their environment. Aims. We studied the compact radio structure of J1429+5447 on the milli-arcsecond (mas) angular scale to compare the structural and spectral properties with those of another two z ? 6 radio-loud quasars, J0836+0054 (z = 5.77) and J1427+3312 (z = 6.12). Methods. We performed Very Long Baseline Interferometry (VLBI) imaging observations of J1429+5447 with the European VLBI Network (EVN) at 1.6 GHz on 2010 June 8, and at 5 GHz on 2010 May 27. Results. Based on its observed radio properties, the compact but somewhat resolved structure on linear scales of <100 pc, and the steep spectrum, the quasar J1429+5447 is remarkably similar to J0836+0054 and J1427+3312. To answer the question whether the compact steep-spectrum radio emission is a “universal” feature of the most distant radio quasars, it is essential to study more yet to be discovered radio-loud active galactic nuclei at z > 6.","techniques; interferometric / radio continuum; galaxies / galaxies; active / quasars; individual; J1429+5447","en","journal article","EDP Sciences","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:83d8a598-cd29-45bb-b0db-f44b4b29aabc","http://resolver.tudelft.nl/uuid:83d8a598-cd29-45bb-b0db-f44b4b29aabc","Mass variation in the Mediterranean Sea from GRACE and its validation by altimetry, steric and hydrologic fields","Fenoglio-Marc, L.; Kusche, J.; Becker, M.","","2006","The seasonal seawater mass variation in the Mediterranean Sea is estimated between April 2002 and July 2004 from GRACE and altimetry data and from hydrologic and oceanographic models. A smoothed spatial averaging kernel is applied to each field, in order to obtain comparable basin averages. The GRACE seawater mass corrected for the leakage of continental hydrology and the filtered steric?corrected altimeter sea level have similar annual amplitude and phase. To restore the magnitude of the GRACE?derived water mass signal we apply a scaling factor to the smoothed annual amplitude. The estimated scaled mass signal has an annual amplitude of 52 ± 17 mm peaking in November. We combine the seawater mass variation with the Mediterranean freshwater deficit and obtain a net flow at the Strait of Gibraltar with annual amplitude of 60 ± 25 mm/month (0.06 Sv) and maximum in September.","","en","journal article","American Geophysical Union","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:3a557db0-7968-474e-a2df-a55c4d4f0834","http://resolver.tudelft.nl/uuid:3a557db0-7968-474e-a2df-a55c4d4f0834","OLFAR: Seeing the unseen; how a cub-sat swarm becomes a novel radio astronomy instrument in space","Verhoeven, C.; Bentum, M.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2f0856b4-a5c2-44e2-9647-c9c5df542317","http://resolver.tudelft.nl/uuid:2f0856b4-a5c2-44e2-9647-c9c5df542317","Improved short-term variability in the thermosphere-ionosphere-mesosphere-electrodynamics general circulation model","Häusler, K.; Hagan, M.E.; Baumgaertner, A.J.G.; Maute, A.; Lu, G.; Doornbos, E.N.; Bruinsma, S.; Forbes, J.M.; Gasperini, F.","","2014","We report on a new source of tidal variability in the National Center for Atmospheric Research thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM). Lower boundary forcing of the TIME-GCM for a simulation of November–December 2009 based on 3-hourly Modern-Era Retrospective Analysis for Research and Application (MERRA) reanalysis data includes day-to-day variations in both diurnal and semidiurnal tides of tropospheric origin. Comparison with TIME-GCM results from a heretofore standard simulation that includes climatological tropospheric tides from the global-scale wave model reveal evidence of the impacts of MERRA forcing throughout the model domain, including measurable tidal variability in the TIME-GCM upper thermosphere. Additional comparisons with measurements made by the Gravity field and steady-state Ocean Circulation Explorer satellite show improved TIME-GCM capability to capture day-to-day variations in thermospheric density for the November–December 2009 period with the new MERRA lower boundary forcing.","TIME-GCM; thermosphere; atmospheric tides; GOCE; lower boundary condition","en","journal article","American Geophysical Union","","","","","","","2015-02-06","Aerospace Engineering","Space Engineering","","","",""
"uuid:96e7be61-e336-4655-acb8-eccb263230ae","http://resolver.tudelft.nl/uuid:96e7be61-e336-4655-acb8-eccb263230ae","Earthquakes and culture shockes; an internship at Nissan","Gardenier, J.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:93c622b6-a98f-4340-9ff2-8ee76210d40f","http://resolver.tudelft.nl/uuid:93c622b6-a98f-4340-9ff2-8ee76210d40f","I don't think we are alone; interview","Van Dijk, T.","Stam, D. (contributor)","2013","There are scores of earth-like planets outside our solar system. Dr Daphne Stam (faculty of Aerospace Engineering) wants to launch a space telescope to search for life on these planets.","","en","journal article","Delft University of Technology","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:e71eff21-ea70-4487-9192-650984a9fbb9","http://resolver.tudelft.nl/uuid:e71eff21-ea70-4487-9192-650984a9fbb9","Internship at Lockheed Martin; living, working and travelling in the USA","Van Dijk, E.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:cb07c088-06d2-44ab-a803-6947e217947d","http://resolver.tudelft.nl/uuid:cb07c088-06d2-44ab-a803-6947e217947d","Tracking and orbit determination performance of the GRAS instrument on MetOp-A","Montenbruck, O.; Andres, Y.; Bock, H.; Van Helleputte, T.; Van den IJssel, J.; Loiselet, M.; Marquardt, M.; Silvestrin, P.; Visser, P.; Yoon, Y.","","2008","The global navigation satellite system receiver for atmospheric sounding (GRAS) on MetOp-A is the first European GPS receiver providing dual-frequency navigation and occultation measurements from a spaceborne platform on a routine basis. The receiver is based on ESA’s AGGA-2 correlator chip, which implements a high-quality tracking scheme for semi-codeless P(Y) code tracking on the L1 and L2 frequency. Data collected with the zenith antenna on MetOp-A have been used to perform an in-flight characterization of the GRAS instrument with focus on the tracking and navigation performance. Besides an assessment of the receiver noise and systematic measurement errors, the study addresses the precise orbit determination accuracy achievable with the GRAS receiver. A consistency on the 5 cm level is demonstrated for reduced dynamics orbit solutions computed independently by four different agencies and software packages. With purely kinematic solutions, 10 cm accuracy is obtained. As a part of the analysis, an empirical antenna offset correction and preliminary phase center correction map are derived, which notably reduce the carrier phase residuals and improve the consistency of kinematic orbit determination results.","Precise orbit determination; Phase center variation; Tracking loops; Semi-codeless tracking; AGGA-2; GRAS; MetOp","en","journal article","Springer","","","","","","","","Aerospace Engineering","Delft Institute of earth Observation and Space Systems","","","",""
"uuid:ff600340-140f-4913-8959-67fe74468b43","http://resolver.tudelft.nl/uuid:ff600340-140f-4913-8959-67fe74468b43","To paint or not?; making a choice between shiny and colourful","Van Dijk, E.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2d67cbb8-a014-4f41-b283-7aaf0767c033","http://resolver.tudelft.nl/uuid:2d67cbb8-a014-4f41-b283-7aaf0767c033","Astrobiology research with cubesats; Cubesats: Powerful science platforms for space explorations","Ehrenfreund, P.; Elsaesser, A.; Ricco, A.J.","","2013","The improvements in the miniaturization of spacecraft and spacecraft subsystems have resulted in a wide variety of small satellites and nanosatellites. This has opened the door to inexpensive, lightweight, small and !exible satellites and missions with various scienti""c applications. One such application could be the use of CubeSats for astrobiological research.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1dfc1d16-ed9b-488f-a866-3a4520c34adc","http://resolver.tudelft.nl/uuid:1dfc1d16-ed9b-488f-a866-3a4520c34adc","Design synthesis exercise 2012","Melkert, J.A.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:648a881a-6c29-45c3-b87a-d93b602e379c","http://resolver.tudelft.nl/uuid:648a881a-6c29-45c3-b87a-d93b602e379c","Geometry-free undifferenced, single and double differenced analysis of single frequency GPS, EGNOS and GIOVE-A/B measurements","De Bakker, P.F.; Van der Marel, H.; Tiberius, C.C.J.M.","","2009","This paper demonstrates a geometry-free GNSS measurement analysis approach and presents results of single frequency GPS, EGNOS and GIOVE short and zero baseline measurements. The purpose is to separate the different contributions to the measurement noise of pseudo range code and carrier phase observations at the receiver. The influence of multipath on the different combinations of observations is also determined. Quantitative results are presented for the thermal code and phase measurement noise and for the correlation between the observations. Comparison of the results with theoretical approximations confirms the validity of the used approach. Results from field measurements clearly show less thermal noise on the Galileo E1BC observations than on the GPS L1C/A observations due to the new signal modulation. The feasibility of ambiguity resolution with a geometry-free model is also discussed including the significant impact of multipath thereon.","GPS; Galileo; GIOVE; EGNOS; Multi-constellation; Geometry-free; Short baseline; Zero baseline; Single frequency; Multipath; Code noise; Phase noise; Ambiguity resolution; Undifferenced; Single; Double; Triple difference","en","journal article","Springer","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:bc1145a0-3e96-4fdf-817d-e0af4670bded","http://resolver.tudelft.nl/uuid:bc1145a0-3e96-4fdf-817d-e0af4670bded","GNSS algebraic structures","Lannes, A.; Teunissen, P.J.G.","","2010","The first objective of this paper is to show that some basic concepts used in global navigation satellite systems (GNSS) are similar to those introduced in Fourier synthesis for handling some phase calibration problems. In experimental astronomy, the latter are at the heart of what is called ‘phase closure imaging.’ In both cases, the analysis of the related structures appeals to the algebraic graph theory and the algebraic number theory. For example, the estimable functions of carrier-phase ambiguities, which were introduced in GNSS to correct some rank defects of the undifferenced equations, prove to be ‘closure-phase ambiguities:’ the so-called ‘closure-delay’ (CD) ambiguities. The notion of closure delay thus generalizes that of double difference (DD). The other estimable functional variables involved in the phase and code undifferenced equations are the receiver and satellite pseudo-clock biases. A related application, which corresponds to the second objective of this paper, concerns the definition of the clock information to be broadcasted to the network users for their precise point positioning (PPP). It is shown that this positioning can be achieved by simply having access to the satellite pseudo-clock biases. For simplicity, the study is restricted to relatively small networks. Concerning the phase for example, these biases then include five components: a frequency-dependent satelliteclock error, a tropospheric satellite delay, an ionospheric satellite delay, an initial satellite phase, and an integer satellite ambiguity. The form of the PPP equations to be solved by the network user is then similar to that of the traditional PPP equations. As soon as the CD ambiguities are fixed and validated, an operation which can be performed in real time via appropriate decorrelation techniques, estimates of these float biases can be immediately obtained. No other ambiguity is to be fixed. The satellite pseudo-clock biases can thus be obtained in real time. This is not the case for the satellite-clock biases. The third objective of this paper is to make the link between the CD approach and the GNSS methods based on the notion of double difference. In particular, it is shown that the information provided by a maximum set of independent DDs may not reach that of a complete set of CDs. The corresponding defect is analyzed. One of the main results of the corresponding analysis concerns the DD–CD relationship. In particular, it is shown that the DD ambiguities, once they have been fixed and validated, can be used as input data in the ‘undifferenced CD equations.’ The corresponding algebraic operations are described. The satellite pseudo-clock biases can therefore be also obtained via particular methods in which the notion of double differencing is involved.","GNSS networks; Phase calibration; Undifferenced and differenced methods; PPP; RTK","en","journal article","Springer","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:3c853c20-a0d5-4401-a54b-b841e211bbcc","http://resolver.tudelft.nl/uuid:3c853c20-a0d5-4401-a54b-b841e211bbcc","Design synthesis exercise. Fall 2013","","","2014","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:328da2cf-3c36-4bb3-90ab-56062335bf78","http://resolver.tudelft.nl/uuid:328da2cf-3c36-4bb3-90ab-56062335bf78","Modelling of the effects of grain orientation on transformation-induced plasticity in multiphase carbon steels","Tjahjanto, D.D.; Turteltaub, S.; Suiker, A.S.J.; Van Der Zwaag, S.","","2006","","","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:386aa507-c8e3-4e71-a634-187541f78ae5","http://resolver.tudelft.nl/uuid:386aa507-c8e3-4e71-a634-187541f78ae5","From Moscow to the moon","Wink, J.","","2013","Due to the strict implementation of the harde knip (BSc. Before MSc. Rule) I found myself with no courses or project work in the spring quarter. I decided to put this time to good use and pursue an internship abroad. This endeavor eventually brought me to the Red Square to contribute to the Russian space program.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3629587c-041d-4742-895b-965718ca9b81","http://resolver.tudelft.nl/uuid:3629587c-041d-4742-895b-965718ca9b81","Glacial isostatic adjustment in the static gravity field of Fennoscandia","Root, B.C.; Van der Wal, W.; Novak, P.; Ebbing, J.; Vermeersen, L.L.A.","","2015","In the central part of Fennoscandia, the crust is currently rising, because of the delayed response of the viscous mantle to melting of the Late Pleistocene ice sheet. This process, called Glacial Isostatic Adjustment (GIA), causes a negative anomaly in the present-day static gravity field as isostatic equilibrium has not been reached yet. Several studies have tried to use this anomaly as a constraint on models of GIA, but the uncertainty in crustal and upper mantle structures has not been fully taken into account. Therefore, our aim is to revisit this using improved crustal models and compensation techniques. We find that in contrast with other studies, the effect of crustal anomalies on the gravity field cannot be effectively removed, because of uncertainties in the crustal and upper mantle density models. Our second aim is to estimate the effects on geophysical models, which assume isostatic equilibrium, after correcting the observed gravity field with numerical models for GIA. We show that correcting for GIA in geophysical modelling can give changes of several kilometer in the thickness of structural layers of modeled lithosphere, which is a small but significant correction. Correcting the gravity field for GIA prior to assuming isostatic equilibrium and inferring density anomalies might be relevant in other areas with ongoing postglacial rebound such as North America and the polar regions.","","en","journal article","American Geophysical Union","","","","","","","2015-07-07","Aerospace Engineering","Space Engineering","","","",""
"uuid:c11e0a62-1e6a-4928-9a76-b9303ab5b419","http://resolver.tudelft.nl/uuid:c11e0a62-1e6a-4928-9a76-b9303ab5b419","A cohesive segments method for the simulation of crack growth","Remmers, J.J.C.; De Borst, R.; Needleman, A.","","2003","A numerical method for crack growth is described in which the crack is not regarded as a single discontinuity that propagates continuously. Instead, the crack is represented by a set of overlapping cohesive segments. These cohesive segments are inserted into finite elements as discontinuities in the displacement field by exploiting the partition-of-unity property of shape functions. The cohesive segments can be incorporated at arbitrary locations and orientations and are not tied to any particular mesh direction. The evolution of decohesion of the segments is governed by a cohesive law. The independent specification of bulk and cohesive constitutive relations leads to a characteristic length being introduced into the formulation. The formulation permits both crack nucleation and discontinuous crack growth to be modelled. The implementation is outlined and some numerical examples are presented.","crack growth; fracture; cohesive zones; partitions of unity","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:2d1417a1-d2f7-49c7-89fc-4ebc7c704e99","http://resolver.tudelft.nl/uuid:2d1417a1-d2f7-49c7-89fc-4ebc7c704e99","SkelTre: Robust skeleton extraction from imperfect point clouds","Bucksch, A.; Lindenbergh, R.; Menenti, M.","","2010","Terrestrial laser scanners capture 3D geometry of real world objects as a point cloud. This paper reports on a new algorithm developed for the skeletonization of a laser scanner point cloud. The skeletonization algorithm proposed in this paper consists of three steps: (i) extraction of a graph from an octree organization, (ii) reduction of the graph to a skeleton, and (iii) embedding of the skeleton into the point cloud. For these three steps, only one input parameter is required. The results are validated on laser scanner point clouds representing 2 classes of objects; first on botanic trees as a special application and secondly on popular arbitrary objects. The presented skeleton found its first application in obtaining botanic tree parameters like length and diameter of branches and is presented here in a new, generalized version. Its definition as Reeb Graph, proofs the usefulness of the skeleton for applications like shape analysis. In this paper we show that the resulting skeleton contains the Reeb Graph and investigate the practically relevant parameters: centeredness and topological correctness. The robustness of this skeletonization method against undersampling, varying point density and systematic errors of the point cloud is demonstrated on real data examples.","Skeletonization; Point cloud; Laser scanning","en","journal article","Springer","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:318fbebe-59ac-452a-8e11-9dbe29c111ea","http://resolver.tudelft.nl/uuid:318fbebe-59ac-452a-8e11-9dbe29c111ea","Atmospheric gravity waves due to the Tohoku-Oki tsunami observed in the thermosphere by GOCE","Garcia, R.F.; Doornbos, E.N.; Bruinsma, S.; Hebert, H.","","2014","Oceanic tsunami waves couple with atmospheric gravity waves, as previously observed through ionospheric and airglow perturbations. Aerodynamic velocities and density variations are computed from Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) accelerometer and thruster data during Tohoku-Oki tsunami propagation. High-frequency perturbations of these parameters are observed during three expected crossings of the tsunami-generated gravity waves by the GOCE satellite. From theoretical relations between air density and vertical and horizontal velocities inside the gravity wave, we demonstrate that the measured perturbations are consistent with a gravity wave generated by the tsunami and provide a way to estimate the propagation azimuth of the gravity wave. Moreover, because GOCE measurements can constrain the wave polarization, a marker (noted C3) of any gravity wave crossing by the GOCE satellite is constructed from correlation coefficients between the observed atmospheric state parameters. These observations validate a new observation tool of thermospheric gravity waves generated by tsunamis above the open ocean.","GOCE mission; tsunami; thermosphere; gravity waves; ocean/atmosphere coupling; accelerometer data","en","journal article","American Geophysical Union","","","","","","","2014-10-21","Aerospace Engineering","Space Engineering","","","",""
"uuid:306785d0-f75b-4378-a145-75905c83efa7","http://resolver.tudelft.nl/uuid:306785d0-f75b-4378-a145-75905c83efa7","An inflatable wing using the principle of Tensairity","Breuer, J.; Ockels, W.; Luchsinger, R.H.","","2007","The paper describes the new concept Tensairity which can be used to significantly improve the load bearing capacity of inflatable wings. The basic principle of Tensairity is to use an inflatable structure to stabilize conventional compression and tension elements. So far, Tensairity has been mainly used in civil engineering application like roof structures and bridges. In this work, considerations to apply Tensairity to wing structures are given and the construction of two wing-like Tensairity kite prototypes is described. Test results on the Tensairity structure used in these kites are presented and compared to purely air inflated structures. Finally, the advantages of Tensairity wings are discussed and some application areas of these wings are suggested.","","en","journal article","American Institute of Aeronautics and Astronautics","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:f1aa9f58-a0ed-4dd7-8771-a6c2f05794a3","http://resolver.tudelft.nl/uuid:f1aa9f58-a0ed-4dd7-8771-a6c2f05794a3","A low cost azomethine-based hole transporting material for perovskite photovoltaics","Petrus, M.L.; Bein, T.; Dingemans, T.J.; Docampo, P.","","2015","Most hole transporting materials (HTMs) prepared for perovskite solar cell applications are synthesized via cross-coupling reactions that require expensive transition metal catalysts, inert reaction conditions and extensive product purification; making large-scale production cost-prohibitive. Here, we describe the synthesis of a simple azomethine-based conjugated small-molecule (EDOT-OMeTPA) which is easily prepared in a cost effective Schiff base condensation reaction, with water being the only by-product. As the hole transporter in planar CH3NH3PbI3 perovskite solar cells, efficiencies exceeding 11% were reached. This result is comparable to state-of-the-art materials such as Spiro-OMeTAD on a like-to-like comparison, while cost estimations show that the material cost is about one order of magnitude lower for EDOT-OMeTPA, resulting in a negligible cost-per-peak-Watt contribution of 0.004 $ W?1. In addition, the high synthetic accessibility of EDOT-OMeTPA also reduces the toxic chemical waste and therefore greatly reduces its environmental impact. Our results pave the way towards low-cost, environmentally friendly and efficient HTMs.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:0103be24-57b8-4e8a-8d3b-008e2838c657","http://resolver.tudelft.nl/uuid:0103be24-57b8-4e8a-8d3b-008e2838c657","Bidirectional current-voltage converters based on magnetostrictive/piezoelectric composites","Jia, Y.; Or, S.W.; Chan, H.L.W.; Jiao, J.; Luo, H.; Van der Zwaag, S.","","2009","We report a power supply-free, bidirectional electric current-voltage converter based on a coil-wound laminated composite of magnetostrictive alloy and piezoelectric crystal. An electric current applied to the coil induces a magnetic field, resulting in an electric voltage from the composite due to the direct magnetoelectric effect. Conversely, an electric voltage applied to the composite produces a magnetic induction due to the converse magnetoelectric effect, leading to an electric current from the coil. The converter exhibits excellent linear relationships between current and voltage. Compared with traditional current/voltage converters made by operational amplifiers, the advantages of the proposed device include low cost, no power consumption, and bidirectional conversion.","convertors; dysprosium alloys; electromagnetic induction; iron alloys; laminates; lead compounds; magnetostriction; magnetostrictive devices; piezoelectric devices; piezoelectricity; terbium alloys","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:df2223a1-72fe-4f87-9a2e-d071ee762a32","http://resolver.tudelft.nl/uuid:df2223a1-72fe-4f87-9a2e-d071ee762a32","The Superbus is taking shape: Manufacturing and assembly processes for the realisation of this new vehicle","Terzi, A.; Ockels, W.J.","","2008","The Superbus was introduced as one of the option for the Zuiderzeelijn : a fast connection between Amsterdam and Groningen and resulted to be the best option, the others being three different types of high speed train and the magnetic levitation train. In order evaluate the feasibility of its implementation, the Dutch Ministry of Transport and Water Management has decided to fund the realization of a demonstrator.","chassis and bodywork design; sustainability; carbon fiber reinforced plastics; injection molding; prototype assembly method","en","journal article","","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:5a77187a-ce71-4ab5-8b06-3548a8b0aa2a","http://resolver.tudelft.nl/uuid:5a77187a-ce71-4ab5-8b06-3548a8b0aa2a","Shape, sizing optimization and material selection based on mixed variables and genetic algorithm","Tang, X.; Bassir, D.H.; Zhang, W.","","2010","In this work, we explore simultaneous designs of materials selection and structural optimization. As the material selection turns out to be a discrete process that finds the optimal distribution of materials over the design domain, it cannot be performed with common gradient-based optimization methods. In this paper, material selection is considered together with the shape and sizing optimization in a framework of multiobjective optimization of tracking the Pareto curve. The idea of mixed variables is often introduced in the case of mono-objective optimization. However, in the case of multi-objective optimization, we still face some hard key points related to the convexity and the continuity of the Pareto domain, which underline the originality of this work. In addition to the above aspect, there is a lack in the literature concerning the industrial applications that consider the mixed parameters. Continuous variables refer to structural parameters such as thickness, diameter and spring elastic constants while material ID is defined as binary design variable for each material. Both mechanical and thermal loads are considered in this work with the aim of minimizing the maximum stress and structural weight simultaneously. The efficiency of the design procedure is demonstrated through various numerical examples.","material selection; shape optimization; mixed design variables; multiobjective optimization; genetic algorithms","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Structures","","","",""
"uuid:6021fce8-1c35-4e0b-92ed-a8417242d00d","http://resolver.tudelft.nl/uuid:6021fce8-1c35-4e0b-92ed-a8417242d00d","Aerodynamic Characterization of ‘DelFly Micro’ in Forward Flight Configuration by Force Measurements and Flow Field Visualization","Deng, S.; Percin, M.; Van Oudheusden, B.","","2015","This study explores the flow structures and unsteady force generation mechanisms of a flapping-wing micro air vehicle ‘DelFly Micro’ in forward flight configuration. Stereoscopic Particle Image Velocimetry (Stereo-PIV) measurements were performed to acquire three dimensional flow fields in the wake. Six components of forces and moments were captured simultaneously by use of a miniature force sensor.","flapping-wing MAV; DelFly Micro; aerodynamic force; wake flow topolygy","en","journal article","Elsevier","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:006ff554-1f47-453a-abf1-3ece89761856","http://resolver.tudelft.nl/uuid:006ff554-1f47-453a-abf1-3ece89761856","On the postprocessing removal of correlated errors in GRACE temporal gravity field solutions","Duan, X.J.; Guo, J.Y.; Shum, C.K.; Van der Wal, W.","","2009","We revisit the empirical moving window filtering method of Swenson and Wahr (Geophys Res Lett 33:L08402, 2006) and its variants, Chambers (Geophys Res Lett 33:L17603, 2006) and Chen et al. (Geophys Res Lett 34: L13302, 2007), for reducing the correlated errors in the Stokes coefficients (SCs) of the spherical harmonic expansion of the GRACE determined monthly geopotential solutions. Based on a comparison of the three published approaches mentioned, we propose a refined approach for choosing parameters of the decorrelation filter. Our approach is based on the error pattern of the SCs in the monthly GRACE geopotential solutions. We keep a portion of the lower degree-order SCs with the smallest errors unchanged, and high-pass filter the rest using a moving window technique, with window width decreasing as the error of the SCs increases. Both the unchanged portion of SCs and the window width conform with the error pattern, and are adjustable with a parameter. Compared to the three published approaches mentioned, our unchanged portion of SCs and window width depend on both degree and order in a more complex way. We have used the trend of mass change to test various parameters toward a preferred choice for a global compromise between the removal of the correlated errors and the minimization of signal distortion.","GRACE; Geopotential coefficients; Correlation","en","journal article","Springer","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:f24a9cd1-97f4-4178-bfad-5d4ada4a64be","http://resolver.tudelft.nl/uuid:f24a9cd1-97f4-4178-bfad-5d4ada4a64be","GOCE gravitational gradients along the orbit","Bouman, J.; Fiorot, S.; Fuchs, M.; Gruber, T.; Schrama, E.J.O.; Tscherning, C.; Veicherts, M.; Visser, P.N.A.M.","","2011","GOCE is ESA’s gravity field mission and the first satellite ever that measures gravitational gradients in space, that is, the second spatial derivatives of the Earth’s gravitational potential. The goal is to determine the Earth’s mean gravitational field with unprecedented accuracy at spatial resolutions down to 100 km. GOCE carries a gravity gradiometer that allows deriving the gravitational gradients with very high precision to achieve this goal. There are two types of GOCE Level 2 gravitational gradients (GGs) along the orbit: the gravitational gradients in the gradiometer reference frame (GRF) and the gravitational gradients in the local north oriented frame (LNOF) derived from the GGs in the GRF by point-wise rotation. Because the V XX , V YY , V ZZ and V XZ are much more accurate than V XY and V YZ , and because the error of the accurate GGs increases for low frequencies, the rotation requires that part of the measured GG signal is replaced by model signal. However, the actual quality of the gradients in GRF and LNOF needs to be assessed. We analysed the outliers in the GGs, validated the GGs in the GRF using independent gravity field information and compared their assessed error with the requirements. In addition, we compared the GGs in the LNOF with state-of-the-art global gravity field models and determined the model contribution to the rotated GGs. We found that the percentage of detected outliers is below 0.1% for all GGs, and external gravity data confirm that the GG scale factors do not differ from one down to the 10?3 level. Furthermore, we found that the error of V XX and V YY is approximately at the level of the requirement on the gravitational gradient trace, whereas the V ZZ error is a factor of 2–3 above the requirement for higher frequencies. We show that the model contribution in the rotated GGs is 2–35% dependent on the gravitational gradient. Finally, we found that GOCE gravitational gradients and gradients derived from EIGEN-5C and EGM2008 are consistent over the oceans, but that over the continents the consistency may be less, especially in areas with poor terrestrial gravity data. All in all, our analyses show that the quality of the GOCE gravitational gradients is good and that with this type of data valuable new gravity field information is obtained.","GOCE; gravitational gradients; external calibration; tensor rotation","en","journal article","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:782639ea-8bcb-4e7d-8991-ecbbbecf6b56","http://resolver.tudelft.nl/uuid:782639ea-8bcb-4e7d-8991-ecbbbecf6b56","Safe symposium; safeguarding aviation in the future effectively","Winters, B.","","2013","This year the Aviation Department had the honour of organising the annual symposium of the VSV ‘Leonardo da Vinci’ on the occasion of its 20th anniversary. On March 5, 2013 approximately 250 students and aviation professionals gathered in the Auditorium of Delft University of Technology to enjoy a day filled with inspirational lectures and educative discussions to gain a deeper understanding in the role that safety plays in the world of aviation.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4045f126-6b59-49b6-968e-8d21cef5c859","http://resolver.tudelft.nl/uuid:4045f126-6b59-49b6-968e-8d21cef5c859","Shearography technology and applications: A review","Francis, D.; Tatam, R.P.; Groves, R.M.","","2010","Shearography is a full-field speckle interferometric technique used to determine surface displacement derivatives. For an interferometric technique, shearography is particularly resilient to environmental disturbances and has hence become an invaluable measurement tool outside of the optics laboratory. Furthermore, the inclusion of additional measurement channels has turned shearography from a qualitative inspection tool into a system suitable for quantitative surface strain measurement. In this review article we present a comprehensive overview of the technique, describing the principle of operation, optical configurations, image processing algorithms and applications, with a focus on more recent technological advances.","shearography, speckle interferometry, non-destructive testing, strain measurement","en","journal article","Institute of Physics","","","","","","","","Aerospace Engineering","Optical Non-Destructive Testing Laboratory","","","",""
"uuid:ff449361-ed4c-4f6e-ae4d-b4211fe44657","http://resolver.tudelft.nl/uuid:ff449361-ed4c-4f6e-ae4d-b4211fe44657","Dynamic buckling analysis of composite cylindrical shells using a finite element based perturbation method","Rahman, T.; Jansen, E.L.; Gürdal, Z.","","2011","In this paper a finite element formulation of a reduction method for dynamic buckling analysis of imperfection-sensitive shell structures is presented. The reduction method makes use of a perturbation approach, initially developed for static buckling and later extended to dynamic buckling analysis. The implementation of a single-mode dynamic buckling analysis in a general purpose finite element code is described. The effectiveness of the approach is illustrated by application to the dynamic buckling of composite cylindrical shells under axial and radial step loads. Results of the reduction method are compared with results available in the literature. The results are also compared with full model finite element explicit dynamic analysis, and a reasonable agreement is obtained.","dynamic buckling; thin-walled structures; finite elements; perturbation method; reduction method","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Structures and Design Methodology","","","",""
"uuid:be8d8d8a-bc0e-4de5-8e78-b8dc6090776c","http://resolver.tudelft.nl/uuid:be8d8d8a-bc0e-4de5-8e78-b8dc6090776c","Towards regional projections of twenty-first century sea-level change based on IPCC SRES scenarios","Slangen, A.B.A.; Katsman, C.A.; Van de Wal, R.S.W.; Vermeersen, L.L.A.; Riva, R.E.M.","","2012","Sea-level change is often considered to be globally uniform in sea-level projections. However, local relative sea-level (RSL) change can deviate substantially from the global mean. Here, we present maps of twenty-first century local RSL change estimates based on an ensemble of coupled climate model simulations for three emission scenarios. In the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4), the same model simulations were used for their projections of global mean sea-level rise. The contribution of the small glaciers and ice caps to local RSL change is calculated with a glacier model, based on a volume-area approach. The contributions of the Greenland and Antarctic ice sheets are obtained from IPCC AR4 estimates. The RSL distribution resulting from the land ice mass changes is then calculated by solving the sea-level equation for a rotating, elastic Earth model. Next, we add the pattern of steric RSL changes obtained from the coupled climate models and a model estimate for the effect of Glacial Isostatic Adjustment. The resulting ensemble mean RSL pattern reveals that many regions will experience RSL changes that differ substantially from the global mean. For the A1B ensemble, local RSL change values range from -3.91 to 0.79 m, with a global mean of 0.47 m. Although the RSL amplitude differs, the spatial patterns are similar for all three emission scenarios. The spread in the projections is dominated by the distribution of the steric contribution, at least for the processes included in this study. Extreme ice loss scenarios may alter this picture. For individual sites, we find a standard deviation for the combined contributions of approximately 10 cm, regardless of emission scenario","regional sea level; sea-level projections; climate change","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6b6fdbc2-4647-401c-8204-96524bedb2c7","http://resolver.tudelft.nl/uuid:6b6fdbc2-4647-401c-8204-96524bedb2c7","Context aware adaptive automation: From autopilot to co-pilot","Comans, J.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a81856a6-4959-4a2c-9b44-9bd3c7960d73","http://resolver.tudelft.nl/uuid:a81856a6-4959-4a2c-9b44-9bd3c7960d73","Effect of GIA models with 3D composite mantle viscosity on GRACE mass balance estimates for Antarctica","Van der Wal, W.; Whitehouse, P.L.; Schrama, E.J.O.","","2015","Seismic data indicate that there are large viscosity variations in the mantle beneath Antarctica. Consideration of such variations would affect predictions of models of Glacial Isostatic Adjustment (GIA), which are used to correct satellite measurements of ice mass change. However, most GIA models used for that purpose have assumed the mantle to be uniformly stratified in terms of viscosity. The goal of this study is to estimate the effect of lateral variations in viscosity on Antarctic mass balance estimates derived from the Gravity Recovery and Climate Experiment (GRACE) data. To this end, recently-developed global GIA models based on lateral variations in mantle temperature are tuned to fit constraints in the northern hemisphere and then compared to GPS-derived uplift rates in Antarctica. We find that these models can provide a better fit to GPS uplift rates in Antarctica than existing GIA models with a radially-varying (1D) rheology. When 3D viscosity models in combination with specific ice loading histories are used to correct GRACE measurements, mass loss in Antarctica is smaller than previously found for the same ice loading histories and their preferred 1D viscosity profiles. The variation in mass balance estimates arising from using different plausible realizations of 3D viscosity amounts to 20 Gt/yr for the ICE-5G ice model and 16 Gt/yr for the W12a ice model; these values are larger than the GRACE measurement error, but smaller than the variation arising from unknown ice history. While there exist 1D Earth models that can reproduce the total mass balance estimates derived using 3D Earth models, the spatial pattern of gravity rates can be significantly affected by 3D viscosity in a way that cannot be reproduced by GIA models with 1D viscosity. As an example, models with 1D viscosity always predict maximum gravity rates in the Ross Sea for the ICE-5G ice model, however, for one of the three preferred 3D models the maximum (for the same ice model) is found near the Weddell Sea. This demonstrates that 3D variations in viscosity affect the sensitivity of present-day uplift and gravity rates to changes in the timing of the ice history. In particular, low viscosities (View the MathML source<1019 Pas) found in West Antarctica make the mantle very sensitive to recent changes in ice thickness.","glacial rebound; mantle rheology; viscosity; time-variable gravity; GRACE; Antarctica","en","journal article","Elsevier","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:fbc554ac-48e5-44c6-aa9d-f87cf0d1e168","http://resolver.tudelft.nl/uuid:fbc554ac-48e5-44c6-aa9d-f87cf0d1e168","Ultrasonic Underside Inspection for Fatigue Cracks in the Deck Plate of a Steel Orthotropic Bridge Deck","Bakker, M.C.M.; De Jong, F.B.P.","","2003","Due to an unexpected increase of heavy traffic large fatigue cracks appeared through the deck plate of orthotropic steel bridge decks in the Netherlands. Visual inspection revealed that this particular type of crack initiates where a weld joins the deck plate, a rib and a girder. These critical points are commonly inspected from the roadside, which necessitates that the road is closed down for all traffic and that the wear layer is first removed. To overcome these costly drawbacks a new method is proposed that enables ultrasonic inspection of the deck plate from the underside of the bridge deck. The method requires a combination of two special measurement techniques, which are optimised for the bridge problem at hand. To detect the maximum crack depth an angled pitch-catch technique is employed. The crack length can be detected along the rib weld by employing the simpler pulse-echo technique. The crack depth and crack length are determined from the respective ultrasonic data sets by a calibration, which relates the number of detected waves to the actual crack size. The calibration is determined by ultrasonically monitoring the various crack stages during a fatigue test that is conducted on a bridge deck specimen. The original, uncracked state and the final state where the cracks can be visibly detected in the deck plate determine the extremes. The tests show that a reasonable accurate detection of crack size is quite possible, while the visual inspections prove to be useless until the crack has already grown completely through the deck plate. The new method provides a crack depth and crack length estimate with an accuracy of ±15 %.","","en","journal article","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:fc5894fe-29b8-4aa8-a927-7286378bc7d7","http://resolver.tudelft.nl/uuid:fc5894fe-29b8-4aa8-a927-7286378bc7d7","Citizen of space: Living in orbit","Dohmen, C.; Beeftink, D.","","2012","An interpretation of the inspiring symposium organised by de VSV 'Leonardo da Vinci'","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:19f31d86-df63-41db-97a1-4796e8fe436a","http://resolver.tudelft.nl/uuid:19f31d86-df63-41db-97a1-4796e8fe436a","Separation of Ground and Low Vegetation Signatures in LiDAR Measurements of Salt-Marsh Environments","Wang, C.; Menenti, M.; Stoll, M.P.; Feola, A.; Belluco, E.; Marani, M.","","2009","Light detection and ranging (LiDAR) has been shown to have a great potential in the accurate characterization of forest systems; however, its application to salt-marsh environments is challenging because the characteristic short vegetation does not give rise to detectable differences between first and last LiDAR returns. Furthermore, the lack of precisely identifiable references (e.g., buildings, roads, etc.) in marsh areas makes the registration and bias correction of the LiDAR data much more difficult than in conventional urban- or forested-area applications. In this paper, we introduce reliable methods to remove random and systematic errors and to register raw data, as well as a new procedure, to determine the optimal filter window size to separate ground and canopy returns. A limited amount of field observations is used to determine the size of the filtering window which produces the minimally biased estimates of the digital terrain model (DTM). The digital surface model (DSM, representing the canopy top) is then obtained in a similar manner, and the digital vegetationmodel (DVM, representing the vegetation height) is computed as the difference between the DSM and the DTM. We apply this procedure to a study marsh within the Venice Lagoon, Italy, and obtain a high-accuracy DTM. The error (z_LiDAR ? z_field) is 2.2 cm, with a standard deviation of 6.4 cm. The comparison of the estimated DVM with field observations shows an underestimation of the height of the canopy top (17.7 cm, on average). The height of the lowest canopy elements (e.g., basal leaves), however, is significantly correlated to the LiDAR-derived DVM, showing that this contains useful information on the canopy structure.","digital terrain model (DTM); digital vegetation model (DVM); light detection and ranging (LiDAR); salt-marsh environments","en","journal article","IEEE","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:a1c00639-6cd8-4f84-abc6-d50a25dbb8b7","http://resolver.tudelft.nl/uuid:a1c00639-6cd8-4f84-abc6-d50a25dbb8b7","Critical current semiconductor nanowire Josephson junctions in the presence of magnetic field","Yokoyama, T.; Eto, M.; Nazarov, Y.V.","","2014","We study theoretically the critical current in semiconductor nanowire Josephson junction with strong spin-orbit interaction. The critical current oscillates with an external magnetic field. We reveal that the oscillation of critical current depends on the orientation of magnetic field in the presence of spin-orbit interaction. We perform a numerical simulation using a tight-binding model. The Andreev levels are calculated as a function of phase difference ? between two superconductors. The DC Josephson current is evaluated from the Andreev levels in the case of short junctions. The spin-orbit interaction induces the effective magnetic field. When the external field is parallel with the effective one, the critical current oscillates accompanying the 0-? like transition at the cusp of critical current. The distance of cusps increases gradually with increasing of the angle between the external and effective fields. The magnetic anisotropy of critical current is attributed to the spin precession due to the spin-orbit interaction.","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:c1b0c72a-83e2-47b0-a7e2-0c3665402ffc","http://resolver.tudelft.nl/uuid:c1b0c72a-83e2-47b0-a7e2-0c3665402ffc","Experimental investigation of aerofoil tonal noise generation","Pröbsting, S.; Serpieri, J.; Scarano, F.","","2014","The present study investigates the mechanisms associated with tonal noise emission from a NACA 0012 aerofoil at moderate incidence (0; 1; 2 and 4 angle of attack) and with Reynolds numbers ranging from 100 000 to 270 000. Simultaneous time-resolved particle image velocimetry (PIV) of the aeroacoustic source region near the trailing edge and acoustic measurements in the far field are performed in order to establish the correspondence between the flow structure and acoustic emissions. Results of these experiments are presented and analysed in view of past research for a number of selected cases. Characteristics of the acoustic emission and principal features of the average flow field agree with data presented in previous studies on the topic. Time-resolved analysis shows that downstream convecting vortical structures, resulting from growing shear layer instabilities, coherently pass the trailing edge at a frequency equal to that of the dominant tone. Therefore, the scattering of the vortical structures and their associated wall pressure fluctuations are identified as tone generating mechanisms for the cases investigated here. Moreover, wavelet analysis of the acoustic pressure and velocity signals near the trailing edge show a similar periodic amplitude modulation which is associated with multiple tonal peaks in the acoustic spectrum. Periodic amplitude modulation of the acoustic pressure and velocity fluctuations on the pressure side are also observed when transition is forced on the suction side, showing that pressure-side events alone can be the cause.","aeroacoustics; boundary layer stability; vortex shedding","en","journal article","Cambridge University Press","","","","","","","2015-04-23","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:8cecb051-3939-494b-99e8-0ebc97ea1a3d","http://resolver.tudelft.nl/uuid:8cecb051-3939-494b-99e8-0ebc97ea1a3d","Measurement of turbulence spectra using scanning pulsed wind lidars","Sathe, A.; Mann, J.","","2012","Turbulent velocity spectra, as measured by a scanning pulsed wind lidar (WindCube), are analyzed. The relationship between ordinary velocity spectra and lidar derived spectra is mathematically very complex, and deployment of the three-dimensional spectral velocity tensor is necessary. The resulting scanning lidar spectra depend on beam angles, line-of-sight averaging, sampling rate, and the full three-dimensional structure of the turbulence being measured, in a convoluted way. The model captures the attenuation and redistribution of the spectral energy at high and low wave numbers very well. The model and measured spectra are in good agreement at two analyzed heights for the u and w components of the velocity field. An interference phenomenon is observed, both in the model and the measurements, when the diameter of the scanning circle divided by the mean wind speed is a multiple of the time between the beam measurements. For the v spectrum, the model and the measurements agree well at both heights, except at very low wave numbers, k1 < 0.005 m?1. In this region, where the spectral tensor model has not been verified, the model overestimates the spectral energy measured by the lidar. The theoretical understanding of the shape of turbulent velocity spectra measured by scanning pulsed wind lidar is given a firm foundation.","lidar measurements; pulsed wind lidar; turbulence spectra","en","journal article","American Geophysical Union","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","","",""
"uuid:67469607-5116-49af-a16a-c45c227f937e","http://resolver.tudelft.nl/uuid:67469607-5116-49af-a16a-c45c227f937e","Thermospheric vorticity at high geomagnetic latitudes from CHAMP data and its IMF dependence","Förster, M.; Haaland, S.E.; Doornbos, E.N.","","2011","Neutral thermospheric wind pattern at high latitudes obtained from cross-track acceleration measurements of the CHAMP satellite above both polar regions are used to deduce statistical neutral wind vorticity distributions and were analyzed in their dependence on the Interplanetary Magnetic Field (IMF). The average pattern confirms the large duskside anticyclonic vortex seen in the average wind pattern and reveals a cyclonic vorticity on the dawnside, which is almost equal in magnitude to the duskside minimum. The outer shape of the vorticity pattern agrees approximately with the outer boundary of region-1 currents in the well-known average current distributions of Iijima and Potemra (1976) The IMF dependence of the vorticity pattern resembles the characteristic FAC and ionospheric plasma drift pattern known from various statistical studies obtained under the same sorting conditions.","","en","journal article","European Geosciences Union","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:677d695b-2030-4032-b0be-93c2a93fd858","http://resolver.tudelft.nl/uuid:677d695b-2030-4032-b0be-93c2a93fd858","Goodbye Matlab! Hello Python! ;changing the programming language in our curriculum","Hoekstra, J.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c086bff0-389a-4d42-a35c-65c807681281","http://resolver.tudelft.nl/uuid:c086bff0-389a-4d42-a35c-65c807681281","Prediction and Validation of the Austenite Phase Fraction upon Intercritical Annealing of Medium Mn Steels","Farahani, H.; Xu, W.; Van der Zwaag, S.","","2015","In this research, the effects of Mn and Si concentration and that of the isothermal intercritical holding temperature on the austenite-to-ferrite (? ? ?) and the martensite-to-austenite (?? ? ?) phase transformations are studied for a series of Fe-C-Mn-Si steels with up to 7 wt pct Mn. The model is based on the local equilibrium (LE) concept. The model predictions are compared to experimental observations. It is found that the austenite volume fraction at the end of intercritical annealing depends significantly on the initial microstructure. For Mn concentrations between 3 and 7 wt pct, the LE model is qualitatively correct. However, at higher Mn levels the discrepancy between the predicted austenite fractions and the experimental values increases, in particular for the ?? ? ? transformation. Intragrain nucleation is held responsible for the higher austenite fractions observed experimentally. Silicon is found have a much smaller effect on the kinetics of the intercritical annealing than Mn.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:d7f9a484-0dc0-4348-9bb7-cbd00927e261","http://resolver.tudelft.nl/uuid:d7f9a484-0dc0-4348-9bb7-cbd00927e261","Unsteady aspects of an incident shock wave/turbulent boundary layer interaction","Humble, R.A.; Scarano, F.; Van Oudheusden, B.W.","","2009","An incident shock wave/turbulent boundary layer interaction at Mach 2.1 is investigated using particle image velocimetry in combination with data processing using the proper orthogonal decomposition, to obtain an instantaneous and statistical description of the unsteady flow organization. The global structure of the interaction is observed to vary considerably in time. Although reversed flow is often measured instantaneously, on average no reversed flow is observed. On an instantaneous basis, the interaction exhibits a multi-layered structure, characterized by a relatively highvelocity outer region and low-velocity inner region. Discrete vortical structures are prevalent along their interface, which create an intermittent fluid exchange as they propagate downstream. A statistical analysis suggests that the instantaneous fullness of the incoming boundary layer velocity profile is (weakly) correlated with the size of the separation bubble and position of the reflected shock wave. The eigenmodes show an energetic association between velocity fluctuations within the incoming boundary layer, separated flow region and across the reflected shock wave, and portray subspace features that represent the phenomenology observed within the instantaneous realizations.","","en","journal article","Cambridge University Press","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:ee380c63-7827-4820-8fa0-5c38ce3f6a99","http://resolver.tudelft.nl/uuid:ee380c63-7827-4820-8fa0-5c38ce3f6a99","Comparing tide gauge observations to regional patterns of sea-level change (1961–2003)","Slangen, A.B.A.; Van de Wal, R.S.W.; Wada, Y.; Vermeersen, L.L.A.","","2014","Although the global mean sea-level budget for the 20th century can now be closed, the understanding of sea-level change on a regional scale is still limited. In this study we compare observations from tide gauges to regional patterns from various contributions to sea-level change to see how much of the regional measurements can be explained. Processes that are included are land ice mass changes and terrestrial storage changes with associated gravitational, rotational and deformational effects, steric/dynamic changes, atmospheric pressure loading and glacial isostatic adjustment (GIA). The study focuses on the mean linear trend of regional sea-level rise between 1961 and 2003. It is found that on a regional level the explained variance of the observed trend is 0.87 with a regression coefficient of 1.07. The observations and models overlap within the 1? uncertainty range in all regions. The main processes explaining the variability in the observations appear to be the steric/dynamic component and the GIA. Local observations prove to be more difficult to explain because they show larger spatial variations, and therefore require more information on small-scale processes.","","en","journal article","European Geosciences Union","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:7cc0122c-03b8-4a35-a3ce-f2937b312396","http://resolver.tudelft.nl/uuid:7cc0122c-03b8-4a35-a3ce-f2937b312396","Haptic feedback; making safety boundaries tangible","Mulder, M.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:874cbce9-e618-47c7-9929-6d9d0e33caa8","http://resolver.tudelft.nl/uuid:874cbce9-e618-47c7-9929-6d9d0e33caa8","Active aeroelastic wing; new technology with an old twist","Jansen, R.; Breur, J.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5cb49f52-5bd5-40ec-8b77-3fa343130dd4","http://resolver.tudelft.nl/uuid:5cb49f52-5bd5-40ec-8b77-3fa343130dd4","Revisiting Greenland ice sheet mass loss observed by GRACE","Schrama, E.J.O.; Wouters, B.","","2011","In this paper we discuss a new method for determining mass time series for 16 hydrological basins representing the Greenland system (GS) whereby we rely on Gravity Recovery and Climate Experiment (GRACE) mission data. In the same analysis we also considered observed mass changes over Ellesmere Island, Baffin Island, Iceland, and Svalbard (EBIS). The summed contribution of the complete system yields a mass loss rate and acceleration of ?252 ± 28 Gt/yr and ?22 ± 4 Gt/yr2 between March 2003 and February 2010 where the error margins follow from two glacial isostatic adjustment (GIA) models and three processing centers providing GRACE monthly potential coefficient sets. We describe the relation between mass losses in the GS and the EBIS region and found that the uncertainties in all areas are correlated. The summed contribution of Ellesmere Island, Baffin Island, Iceland, and Svalbard yields a mass loss rate of ?51 ± 17 Gt/yr and an acceleration of ?13 ± 3 Gt/yr2 between March 2003 and February 2010. The new regional basin reconstruction method shows that the mass loss within the southeastern basins in the GS has slowed down since 2007, while mass loss in western basins increased showing a progression to the north of Greenland.","GRACE; temporal gravity; Greenland ice sheet","en","journal article","American Geophysical Union","","","","","","","2011-08-12","Aerospace Engineering","Space Engineering","","","",""
"uuid:75f99adf-faac-4c38-abd1-f57ba3c4b1a3","http://resolver.tudelft.nl/uuid:75f99adf-faac-4c38-abd1-f57ba3c4b1a3","Aerodynamic load charaterization of a low speed aerofoil using particle image velocimetry","Van Oudheusden, B.W.; Casimiri, E.W.F.; Scarano, F.","","2008","","","en","journal article","The Royal Aeronautical Society","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e2a748cd-1dd9-461e-b86a-64445d954bdb","http://resolver.tudelft.nl/uuid:e2a748cd-1dd9-461e-b86a-64445d954bdb","Design of a deployment rotation mechanism for microsatellite","Abdelal, G.F.; Bakr Elhady, A.; Kassab, M.","","2009","Solar array rotation mechanism provides a hinged joint between the solar panel and satellite body, smooth rotation of the solar array into deployed position and its fixation in this position. After unlocking of solar panel (while in orbit), rotation bracket turns towards ready-to-work position under the action of driving spring. During deployment, once reached the required operating angle (defined by power subsystem engineer), the rotation bracket collides with the fixed bracket that is mounted on body of the satellite, to stop rotation. Due to the effect of collision force that may alter the rotation mechanism function, design of centrifugal brake is essential. At stoppage moment micro-switches activate final position sensor and a stopper locks the rotation bracket. Design of spring and centrifugal brake components, static finite element stress analysis of primary structure body of rotation mechanism at stoppage moment have been obtained. Last, reliability analysis of rotation mechanism is evaluated. The benefit of this study is to aid in the design of rotation mechanism that can be used in micro-satellite applications.","aerospace; satellite; structure; rotation Mechanism; spring; centrifugal brake; finite element; reliability","en","journal article","EDP sciences","","","","","","","","Aerospace Engineering","Aerospace Structures","","","",""
"uuid:af6f134e-7621-46f9-847e-fd129c5c6f5a","http://resolver.tudelft.nl/uuid:af6f134e-7621-46f9-847e-fd129c5c6f5a","Atomic displacement in solids: Analysis of the primary event and the collision cascade. Part I: Neutron and positive ion irradiation","De Almeida, P.; Räisäinen, J.","","2005","","","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c72234b0-359e-4387-8154-93c8bea8c7e5","http://resolver.tudelft.nl/uuid:c72234b0-359e-4387-8154-93c8bea8c7e5","Design synthesis exercise 2011","Melkert, J.A.","","2011","","design","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c7f3d002-7a01-4a48-8ec1-c84a8a3c10bd","http://resolver.tudelft.nl/uuid:c7f3d002-7a01-4a48-8ec1-c84a8a3c10bd","The NASA Ames Academy for space exploration; getting an insight into the American Space Industry","Reijneveld, J.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:86c70d4d-c23b-4cd7-ba47-93bdd0f9a4fe","http://resolver.tudelft.nl/uuid:86c70d4d-c23b-4cd7-ba47-93bdd0f9a4fe","The aero-acoustic resonance behavior of partially covered slender cavities","De Jong, A.T.; Bijl, H.; Scarano, F.","","2011","The present investigation focuses on the aero-acoustic resonance of cavities with a width much larger than their length or depth and partially covered, as often encountered in automotive door gaps. The cavities are under influence of a low Mach number flow with a relatively thick boundary layer. Under certain conditions, these cavities can acoustically resonate with the flow. The upstream and downstream edge of the opening as well as the cover lip overhang location and boundary layer thickness are parametrically varied in an experimental campaign, and the effect of the parameters on the resonance amplitude is investigated. Slender rectangular cavity geometries with an opening length of 8 mm and spanwise width of 500 mm are used. The cavity flow-induced acoustic response is measured with pressure transducers at different spanwise locations inside the cavity. Hot-wire measurements are performed to quantify the boundary layer characteristics. Furthermore, high-speed time-resolved particle image velocimetry is used to capture the instantaneous velocity field around the opening geometries. When the boundary layer thickness is increased, the cavity resonance amplitude diminishes. The cover lip overhang location has a large influence on the resonance response, which can be attributed to changes in the cavity driven flow properties. Rounding of the upstream edge promotes resonance, whereas rounding of the downstream edge can diminish it. A possible explanation of the phenomenon is given on the basis of the PIV observations.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:95236f38-20af-4e35-b6a9-843a6753a0e4","http://resolver.tudelft.nl/uuid:95236f38-20af-4e35-b6a9-843a6753a0e4","Pressure sources versus surface loads: Analyzing volcano deformation signal composition with an application to Hekla volcano, Iceland","Grapenthin, R.; Ófeigsson, B.G.; Sigmundsson, F.; Sturkell, E.; Hooper, A.J.","","2010","The load of lava emplaced over periods of decades to centuries induces a gradual viscous response of the Earth resulting in measurable deformation. This effect should be considered in source model inversions for volcanic areas with large lava production and flow emplacement in small centralized regions. If deformation data remain uncorrected, constructive load and pressure source interference may result in an overestimate of depth and volume of a magma reservoir whereas destructive signal interference may cause these values to be underestimated. In both cases the source geometry preference could be biased. The ratio of horizontal and vertical displacements aids the identification of composite signals. We provide a method to quantify and remove the lava load deformation signals, using deformation at Hekla volcano, Iceland as an example.","volcano deformation; Mogi model; geodesy","en","journal article","American Geophysical Union","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:2f19000e-f2b5-468e-8d10-5e338e1be888","http://resolver.tudelft.nl/uuid:2f19000e-f2b5-468e-8d10-5e338e1be888","The science of making more torque from wind: Diffuser experiments and theory revisited","Van Bussel, G.J.W.","","2007","","","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9d5ce6eb-2d6d-4b39-be4b-83c958cc93b9","http://resolver.tudelft.nl/uuid:9d5ce6eb-2d6d-4b39-be4b-83c958cc93b9","D-Jet - the future of executive travelling","Hak, M.","","2012","Internship at Diamond Aircraft Industries in London (Ontario), Canada","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:21d4e3af-bdea-4b91-b01e-bf094e9a7d61","http://resolver.tudelft.nl/uuid:21d4e3af-bdea-4b91-b01e-bf094e9a7d61","Sound Transmission Loss Prediction of the Composite Fuselage with Different Methods","Yuan, C.; Bergsma, O.; Beukers, A.","","2012","Increase of sound transmission loss(TL) of the fuselage is vital to build a comfortable cabin environment. In this paper, to find a convenient and accurate means for predicting the fuselage TL, the fuselage is modeled as a composite cylinder, and its TL is predicted with the analytical, the statistic energy analysis (SEA) and the hybrid FE&SEA method. The TL results predicted by the three methods are compared to each other and they show good agreement, but in terms of model building the SEA method is the most convenient one. Therefore, the parameters including the layup, the materials, the geometry, and the structure type are studied with the SEA method. It is observed that asymmetric laminates provide better sound insulation in general. It is further found that glass fiber laminates result in the best sound insulation as compared with graphite and aramid fiber laminates. In addition, the cylinder length has little influence on the sound insulation, while an increase of the radius considerably reduces the TL at low frequencies. Finally, by a comparison among an unstiffened laminate, a sandwich panel and a stiffened panel, the sandwich panel presents the largest TL at high frequencies and the stiffened panel demonstrates the poorest sound insulation at all frequencies.","sound transmission loss; SEA; fuselage; cylinder","en","journal article","Springer-Verlag","","","","","","","","Aerospace Engineering","Aerspace Structures and Materials","","","",""
"uuid:bb51e1e8-e972-4411-b346-47dc9bb389e9","http://resolver.tudelft.nl/uuid:bb51e1e8-e972-4411-b346-47dc9bb389e9","Thermospheric zonal mean winds and tides revealed by CHAMP","Lieberman, R.S.; Akmaev, R.A.; Fuller-Rowell, T.J.; Doornbos, E.","","2013","We present direct, global observations of longitudinally averaged CHAMP zonal winds gathered between 2003 and 2007. A diurnal variation dominates the global zonal wind. Westward flows are observed from the early morning through afternoon hours, while eastward flows peak in the evening. A semidiurnal harmonic is also present, with magnitudes that are approximately one third of the diurnal harmonic. The time mean wind indicates westward winds over much of the globe, with weak superrotation (+E, or eastward winds) that is symmetric about the equator during equinox, and confined to the winter hemisphere at solstice. Diurnal and time mean CHAMP winds agree fairly well with the Whole Atmosphere Model. Some differences are observed in the semidiurnal and higher?order tidal winds, that underscore the challenges of modeling the sources, sinks, and mean wind effects upon tides between the surface and 400?km.","thermosphere; tides; winds","en","journal article","American Geophysical Union","","","","","","","2013-11-30","Aerospace Engineering","Space Engineering","","","",""
"uuid:0e2b720d-4182-4c25-8c70-33e3405a080b","http://resolver.tudelft.nl/uuid:0e2b720d-4182-4c25-8c70-33e3405a080b","Signal processing in optical coherence tomography for aerospace material characterization","Liu, P.; Groves, R.M.; Benedictus, R.","","2013","Based on a customized time-domain optical coherence tomography (OCT) system, a series of signal processing approaches have been designed and reviewed. To improve demodulation accuracy and image quality, demodulation approaches such as median filter, Hilbert transform, and envelope detector were investigated with simulated as well as experimental data. Without noise, the Hilbert transform has the best performance, but after considering the narrow-band noise in the modulated signal, the envelope detector was selected as the ideal demodulation technique. To reduce noise and enhance image contrast, digital signal processing techniques such as a bandpass filtering and two-dimensional median filtering were applied before and after the demodulation, respectively. Finally with integration of the customized OCT setup and designed signal processing algorithms, aerospace materials, such as polymer coatings and glass-fiber composites, were successfully characterized. The cross-sectional images obtained clearly show the microstructures of the materials.","optical coherence tomography; signal processing; demodulation; median filter; aerospace materials; microstructure","en","journal article","SPIE (International Society for Optical Engineering)","","","","","","","","Aerospace Engineering","Aerspace Structures and Materials","","","",""
"uuid:1e638cdb-4c79-48e9-a76e-3df225c73af7","http://resolver.tudelft.nl/uuid:1e638cdb-4c79-48e9-a76e-3df225c73af7","A comparison of coincident GRACE and ICESat data over Antarctica","Gunter, B.; Urban, T.; Riva, R.; Helsen, M.; Harpold, R.; Poole, S.; Nagel, P.; Schutz, B.; Tapley, B.","","2009","In this study, we present a comparison of coincident GRACE and ICESat data over Antarctica. The analysis focused on the secular changes over a 4-year period spanning from 2003 to 2007, using the recently reprocessed and publicly available data sets for both missions. The results show that the two independent data sets possess strong spatial correlations, but that there are several factors that can significantly impact the total derived ice mass variability from both missions. For GRACE, the primary source of uncertainty comes from the modelling of glacial isostatic adjustment, along with the estimates of C 2,0 and the degree one terms. For ICESat, it is shown that assumptions about firn density, rate biases, and the sampling interval of the various laser campaigns can have large effects on the results. Despite these uncertainties, the similarities that do exist indicate a strong potential for the future refinement of both GIA and mass balance estimates of Antarctica.","GRACE; ICESat; Antarctica; Ice mass change; Glacial isostatic adjustment (GIA)","en","journal article","Springer","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:65aa626c-e95b-4a67-8815-3ee2ac40944c","http://resolver.tudelft.nl/uuid:65aa626c-e95b-4a67-8815-3ee2ac40944c","Patrones fenologico de la provincia de Mendoza, Argentina: Mediante serie temporal de imágenes NOAA - AVHRR NDI GAC","González Loyarte, M.M.; Menenti, M.; Roig, F.A.","","2010","Phenological patterns of the province of Mendoza, Argentina, through a temporal series of NOAA-AVHRR NDVI GAC images. The temporal dynamics of vegetation in Mendoza is described through analysis of regional foliar phenology using a series of 108 monthly NOAA-AVHRR NDVI GAC images. A Fast Fourier Transform was used to decompose the series into dynamic parameters: mean NDVI, amplitudes (maximum NDVI variability) and phases (time from start of cycle to maximum NDVI) for different time periods. A classification is made based on those parameters with larger information content (inter- and intra-annual variability), achieving a map of 18 areas of phenological behaviour. This map is related to ecosystems and vegetation units. The phenological pattern (monthly NDVI curve) is modelled for 17 vegetation units. The map contributes dynamic elements to the regional study of vegetation, generating a new zonation explained by variables that determine vegetative activity. The phenological pattern describes the functioning of vegetation and allows understanding of its geographic variations. The overall vegetation of Mendoza responds to an annual cycle with localized weak bimodal patterns. The patterns of low winter-summer contrast correspond to xeric climate conditions, expressing the vegetative maximum at the end of the summer; water availability enhances this contrast, shortening the time of maximum vegetative expression.","foliar phenology; NOAA-AVHRR NDVI GAC images; fourier transform; vegetation; NDVI modelling; phenological behaviour; phenological pattern","","journal article","Sociedad Argentina de Botanica","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:cae9789e-4dbc-4bc1-beb4-214e5d8a2237","http://resolver.tudelft.nl/uuid:cae9789e-4dbc-4bc1-beb4-214e5d8a2237","Low toxicity rocket propellants","Wink, J.","","2014","Hydrazine (N2H4) and its hypergolic mate nitrogen tetroxide (N2O4) are used on virtually all spacecraft and on a large number of launch vehicles. In recent years however, there has been an effort in identifying and developing alternatives to replace hydrazine as a rocket propellant.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c4467281-8f10-4f42-8e07-7eec363f6469","http://resolver.tudelft.nl/uuid:c4467281-8f10-4f42-8e07-7eec363f6469","Three-dimensional vorticity patterns of cylinder wakes","Scarano, F.; Poelma, C.","","2009","The vortex organization of cylinder wakes is experimentally studied by time-resolved tomographic Particle Image Velocimetry at Reynolds numbers ranging from 180 to 5,540. Time resolved measurements are performed at Re = 180, 360 and 540, whereas the transitional (Re = 1,080) and turbulent regimes (Re = 5,540) are investigated by snapshots separated in phase by more than ?/4. The vortex structure evolution is visualized by the 3D vorticity field, revealing a regular shedding at the lowest Reynolds, whereas at Re > 500 the Bénard-Kármán vortex street exhibits counter-rotating stream-wise vortex pairs (characteristic of Mode B) dominating the 3D motion. The regime at Re = 360 produces a transitional pattern where the counter-rotating vortex pairs (Mode B), coexist with profoundly distorted shedding of oblique elements forming a chain of rhombus-like vortex cells. In the turbulent flow regime (Re = 5,540) a large increase in the range of flow scales is directly observed with the appearance of Kelvin-Helmholtz type vortices in the separated shear layer consistently with what is abundantly reported in literature. The statistical description of the secondary structures is inferred from a 3D autocorrelation analysis yielding two span-wise wavelengths for the counter-rotating pairs, an inner length given by (twice) the distance between counter-rotating elements and an outer one given by the distance between pairs. The uncertainty analysis of the present tomographic PIV experiments reveals that this approach is suited for the investigation of vortex wakes with a typical error of 2 and 10% on the velocity and vorticity vectors, respectively.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:d175d2aa-07c8-4f49-ab7d-53f926b95c93","http://resolver.tudelft.nl/uuid:d175d2aa-07c8-4f49-ab7d-53f926b95c93","A career in aviation safety; revealing a multidisciplinary field of engineering at the cutting edge of aviation","Mohrmann, F.","","2013","“On October 18, 2011, around 1315 eastern daylight time, a Berger Waiex, N75654, was substantially damaged following a loss of aircraft control and collision with terrain near Washington, Georgia. The certificated sport pilot was killed. The aircraft wreckage, except for its “Y-tail” assembly, was found in a wooded ravine, about 2.3 nautical miles north of IIY. The Y-tail was found separated, near a dirt road, about 550 feet southwest of the main wreckage.” (NTSB, 2011)","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e77ab570-e7be-4851-8a90-d6ddce1cb0b9","http://resolver.tudelft.nl/uuid:e77ab570-e7be-4851-8a90-d6ddce1cb0b9","The origins of a wind turbine tip vortex","Micallef, D.; Akay, B.; Simao Ferreira, C.J.; Sant, T.; Van Bussel, G.J.W.","","2014","The tip vortex of a wind turbine rotor blade originates as a result of a complex distribution of vorticity along the blade tip thickness. While the tip vortex evolution was extensively studied previously in other work, the mechanism of the initiation of the tip vorticity in a 3D rotating environment is still somewhat obscured due to lack of detailed experimental evidence. This paper therefore aims at providing an understanding of how tip vorticity is formed at the wind turbine blade tip and what happens just behind the tip trailing edge. Stereo Particle Image Velocimetry (SPIV) is used to measure the flow field at the tip of a 2m diameter, two- bladed rotor at the TU Delft Open Jet Facility (OJF). The rotor has a rectangular blade tip. Spanwise measurements were performed for both axial and yawed flow conditions with a very small azimuthal increment. A 3D, unsteady, potential flow panel method is also used for the purpose of better understanding the tip bound vorticity. A validation study is carried out with positive results. This paper is focused on axial flow results. A complex distribution of vorticity is found along the blade tip thickness. Just after release, the tip vortex becomes almost immediately round and well defined. Observations from the MEXICO rotor are confirmed again by a slight inboard convection of the tip vortex. This is explained by means of the effect of chordwise vorticity at the tip from the numerical solutions. The results presented in this work suggest that a more physical interpretation of the tip loss effect is required. Currently, inclusion of tip effects are based primarily on either wake induced effects or on an empirical 3D correction for airfoil data. This research should stimulate a more rigorous approach, where the effects of the blade tip chordwise vorticity are implemented in tip correction models.","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:50fb75fd-6eab-4333-be1e-809d0a7293ba","http://resolver.tudelft.nl/uuid:50fb75fd-6eab-4333-be1e-809d0a7293ba","Shaping up blunt bodies","Muller, M.","Van Raemdonck, G.M.R. (contributor); Van Tooren, M.J.L. (contributor); Beukers, A. (contributor)","2007","Lorries are great for transporting goods, but their inferior aerodynamics means they get fewer kilometers a liter of fuel. Bad news indeed for the environment, and for hauliers purses. But according to researchers at Delft University of Technology, cones and wings attached to the rear end along with technical tricks suspended under the vehicle could reduce fuel consumption by up to fifteen percent.","transport; aerodynamics","en","journal article","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2086086e-b857-4100-828e-6d2a3f6a3408","http://resolver.tudelft.nl/uuid:2086086e-b857-4100-828e-6d2a3f6a3408","Size sensitivity for the reliability index in stochastic finite element analysis of damage","Gutiérrez, M.A.","","2006","The direct differentiation method is applied to the estimation of statistical size effect behaviour in quasi-brittle solids. The scale factor is included in the finite element model and the autocorrelation function. Particular attention is paid to the proper differentiation of the Nataf transformation, which has been chosen to convert the basic random variables into a set of uncorrelated, standard normal variables. The predictive possibilities of the presented algorithm provide a valuable insight in the actual mechanisms responsible for failure. It can be evaluated to what extent the scale factor sensitivity of the failure probability is influenced by the phenomena related to the material disorder or the deterministic size effect.","quasi-brittle material; reliability method; sensitivity; statistical size effect; stochastic finite; elements","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:8ef44314-dfe4-4925-8d67-6445de07fb28","http://resolver.tudelft.nl/uuid:8ef44314-dfe4-4925-8d67-6445de07fb28","Mapping atmospheric aerosols with a citizen science network of smartphone spectropolarimeters","Snik, F.; Rietjens, J.H.H.; Apituley, A.; Volten, H.; Mijling, B.; Di Noia, A.; Heikamp, S.; Heinsbroek, R.C.; Hasekamp, O.P.; Smit, J.M.; Vonk, J.; Stam, D.M.; Van Harten, G.; De Boer, J.; Keller, C.U.","","2014","To assess the impact of atmospheric aerosols on health, climate, and air traffic, aerosol properties must be measured with fine spatial and temporal sampling. This can be achieved by actively involving citizens and the technology they own to form an atmospheric measurement network. We establish this new measurement strategy by developing and deploying iSPEX, a low-cost, mass-producible optical add-on for smartphones with a corresponding app. The aerosol optical thickness (AOT) maps derived from iSPEX spectropolarimetric measurements of the daytime cloud-free sky by thousands of citizen scientists throughout the Netherlands are in good agreement with the spatial AOT structure derived from satellite imagery and temporal AOT variations derived from ground-based precision photometry. These maps show structures at scales of kilometers that are typical for urban air pollution, indicating the potential of iSPEX to provide information about aerosol properties at locations and at times that are not covered by current monitoring efforts.","aerosols; polarimetry; citizen science; smartphones","en","journal article","American Geophysical Union","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:9f931556-f3cf-45f0-b92f-ebcf4af8abc7","http://resolver.tudelft.nl/uuid:9f931556-f3cf-45f0-b92f-ebcf4af8abc7","On a stronger-than-best property for best prediction","Teunissen, P.J.G.","","2007","The minimum mean squared error (MMSE) criterion is a popular criterion for devising best predictors. In case of linear predictors, it has the advantage that no further distributional assumptions need to be made, other then about the first- and second-order moments. In the spatial and Earth sciences, it is the best linear unbiased predictor (BLUP) that is used most often. Despite the fact that in this case only the first- and second-order moments need to be known, one often still makes statements about the complete distribution, in particular when statistical testing is involved. For such cases, one can do better than the BLUP, as shown in Teunissen (J Geod. doi: 10.1007/s00190-007-0140-6, 2006), and thus devise predictors that have a smaller MMSE than the BLUP. Hence, these predictors are to be preferred over the BLUP, if one really values the MMSE-criterion. In the present contribution, we will show, however, that the BLUP has another optimality property than the MMSE-property, provided that the distribution is Gaussian. It will be shown that in the Gaussian case, the prediction error of the BLUP has the highest possible probability of all linear unbiased predictors of being bounded in the weighted squared norm sense. This is a stronger property than the often advertised MMSE-property of the BLUP.","Minimum mean squared error (MMSE) prediction; Least-squares collocation; Universal Kriging; Best linear unbiased prediction (BLUP); Maximum probability of bounded prediction error","en","journal article","Springer","","","","","","","","Aerospace Engineering","Delft Institute for Earth Observation and Space Systems (DEOS)","","","",""
"uuid:bb08261f-0e6a-4def-bcce-fb27fb8311f2","http://resolver.tudelft.nl/uuid:bb08261f-0e6a-4def-bcce-fb27fb8311f2","Where is my jetpack? The history of backmounted propulsion devices","Schneiders, J.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:93e5187f-ef6d-480a-bc68-b2df646d9a82","http://resolver.tudelft.nl/uuid:93e5187f-ef6d-480a-bc68-b2df646d9a82","Modeling of soft impingement effect during solid-state partitioning phase transformations in binary alloys","Chen, H.; Van der Zwaag, S.","","2010","The soft impingement effect at the later stage of partitioning phase transformations has been modeled both for the diffusion-controlled growth model and for the mixed-mode model. Instead of the linear and exponential approximations for the concentration gradient in front of the interface used in the past, a general polynomial method of dealing with the diffusion field is proposed. The linear and exponential diffusion field approximations are two specific cases of the polynomial diffusion field approximation. The effect of soft impingement on the overall partitioning phase transformation is only related to the degree of the super-saturation in case of the diffusion-controlled growth model, while it is determined by both the growth mode and the degree of super-saturation in case of the mixed-mode model.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Materials and Manufacturing","","","",""
"uuid:06a2f08f-d506-4b8c-89f1-418e4937bc0b","http://resolver.tudelft.nl/uuid:06a2f08f-d506-4b8c-89f1-418e4937bc0b","Comparison of CFD simulations to non-rotating MEXICO blades experiment in the LTT wind tunnel of TUDelft","Zhang, Y.; Van Zuijlen, A.; Van Bussel, G.","","2014","In this paper, three dimensional flow over non-rotating MEXICO blades is simulated by CFD methods. The numerical results are compared with the latest MEXICO wind turbine blades measurements obtained in the low speed low turbulence (LTT) wind tunnel of Delft University of Technology. This study aims to validate CFD codes by using these experimental data measured in well controlled conditions. In order to avoid use of wind tunnel corrections, both the blades and the wind tunnel test section are modelled in the simulations. The ability of Menter's k-w shear stress transport (SST) turbulence model is investigated at both attached flow and massively separated flow cases. Steady state Reynolds averaged Navier Stokes (RANS) equations are solved in these computations. The pressure distribution at three measured sections are compared under the conditions of different in flow velocities and a range of angles of attack. The comparison shows that at attached flow condition, good agreement can be obtained for all three airfoil sections. Even with massively separated flow, still fairly good pressure distribution comparison can be found for the DU and NACA airfoil sections, although the RIS¬ section shows poor comparison. At the near stall case, considerable deviations exists on the forward half part of the upper surface for all three sections.","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:1231be7f-bdf8-484b-8f98-6695768f10c0","http://resolver.tudelft.nl/uuid:1231be7f-bdf8-484b-8f98-6695768f10c0","Sir Geoffrey de Havilland, aerospace engineer; a portrait of the achievements and challenges of one the most innovative aircraft designers of the twentieth century","Van Houten, D.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5d80bfe4-27ba-4226-9f39-46c25e7e5a36","http://resolver.tudelft.nl/uuid:5d80bfe4-27ba-4226-9f39-46c25e7e5a36","Skylon; potentially the new big thing in LEO transport","Van der Peijl, I.; Veraart, M.","","2013","Space planes could very well be the ultimate aerospace engineering machine. These space planes are vehicles that function both as an aircraft when flying or gliding through the atmosphere, and as a spacecraft when orbiting around the earth. Well known examples of space planes are NASA’s space shuttle, which launches as a rocket, but re-enters as a glider, and XCORs Lynx, which takes off horizontally with four rocket engines, reaching suborbital flight. Since the twenty-first century, there is a new competitor on the market: Reaction Engines Limited (REL), with their space plane called Skylon.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ea5c338e-43c6-498f-84f5-2bb664605f54","http://resolver.tudelft.nl/uuid:ea5c338e-43c6-498f-84f5-2bb664605f54","Specific gust shapes leading to extreme response of pitch-regulated wind turbines","Bierbooms, W.","","2007","","","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f07b3a59-3014-4337-964c-6f96f6e0c8c3","http://resolver.tudelft.nl/uuid:f07b3a59-3014-4337-964c-6f96f6e0c8c3","Relative state estimation and observability analysis for formation flying satellites","Maessen, D.C.; Gill, E.K.A.","","2012","","","en","journal article","AIAA","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:61a207d6-918d-4984-83cc-93ddd68a1a4d","http://resolver.tudelft.nl/uuid:61a207d6-918d-4984-83cc-93ddd68a1a4d","But how much does it weight? ; structural weight estimation of aircraft lifting surfaces","Elham, A.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e599bcd2-dcff-4cfa-8c6c-09b132c06f1b","http://resolver.tudelft.nl/uuid:e599bcd2-dcff-4cfa-8c6c-09b132c06f1b","A temperature oscillation instrument to determine pyroelectric properties of materials at low frequencies: Towards elimination of lock-in methods","Khanbareh, H.; Schelen, J.B.J.; Van der Zwaag, S.; Groen, W.A.","","2015","Pyroelectric properties of materials can be accurately determined by applying a new digital signal processing method on the discrete sampled data obtained with a temperature oscillation technique. The pyroelectric coefficient is calculated from the component of the generated current 90? out of phase with respect to the sinusoidal temperature wave. The novelty of the proposed approach lies in the signal analysis procedure which implements a simple Fast Fourier transform that filters residual noise through convolution, and calculates the phase difference between the peaks of the temperature and current waves. The new idea requires relatively simple hardware and enables very accurate measurement of the pyroelectric coefficient of materials at ultra low frequencies, 1–250 mHz, without using costly lock-in amplifiers.","","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:88fe8b57-7d70-4358-beb1-f1bb4375e58a","http://resolver.tudelft.nl/uuid:88fe8b57-7d70-4358-beb1-f1bb4375e58a","Antarctic contribution to sea level rise observed by GRACE with improved GIA correction","Ivins, E.R.; James, T.S.; Wahr, J.; Schrama, E.J.O.; Landerer, F.W.; Simon, K.M.","","2013","Antarctic volume changes during the past 21 thousand years are smaller than previously thought, and here we construct an ice sheet history that drives a forward model prediction of the glacial isostatic adjustment (GIA) gravity signal. The new model, in turn, should give predictions that are constrained with recent uplift data. The impact of the GIA signal on a Gravity Recovery and Climate Experiment (GRACE) Antarctic mass balance estimate depends on the specific GRACE analysis method used. For the method described in this paper, the GIA contribution to the apparent surface mass change is re-evaluated to be +55±13 Gt/yr by considering a revised ice history model and a parameter search for vertical motion predictions that best fit the GPS observations at 18 high-quality stations. Although the GIA model spans a range of possible Earth rheological structure values, the data are not yet sufficient for solving for a preferred value of upper and lower mantle viscosity nor for a preferred lithospheric thickness. GRACE monthly solutions from the Center for Space Research Release 04 (CSR-RL04) release time series from January 2003 to the beginning of January 2012, uncorrected for GIA, yield an ice mass rate of +2.9± 29 Gt/yr. The new GIA correction increases the solved-for ice mass imbalance of Antarctica to ?57±34 Gt/yr. The revised GIA correction is smaller than past GRACE estimates by about 50 to 90 Gt/yr. The new upper bound to the sea level rise from the Antarctic ice sheet, averaged over the time span 2003.0–2012.0, is about 0.16±0.09 mm/yr.","Antarctica; sea level rise; ice sheet mass balance; GRACE; GIA models; mantle viscosity","en","journal article","American Geophysical Union","","","","","","","2013-12-14","Aerospace Engineering","Space Engineering","","","",""
"uuid:1012257e-c0c9-4843-929c-72034cc2e42a","http://resolver.tudelft.nl/uuid:1012257e-c0c9-4843-929c-72034cc2e42a","Least-squares variance component estimation","Teunissen, P.J.G.; Amiri-Simkooei, A.R.","","2007","Least-squares variance component estimation (LS-VCE) is a simple, flexible and attractive method for the estimation of unknown variance and covariance components. LS-VCE is simple because it is based on the well-known principle of LS; it is flexible because it works with a user-defined weight matrix; and it is attractive because it allows one to directly apply the existing body of knowledge of LS theory. In this contribution, we present the LS-VCE method for different scenarios and explore its various properties. The method is described for three classes of weight matrices: a general weight matrix, a weight matrix from the unit weight matrix class; and a weight matrix derived from the class of elliptically contoured distributions. We also compare the LS-VCE method with some of the existing VCE methods. Some of them are shown to be special cases of LS-VCE. We also show how the existing body of knowledge of LS theory can be used to one’s advantage for studying various aspects of VCE, such as the precision and estimability of VCE, the use of a-priori variance component information, and the problem of nonlinear VCE. Finally, we show how the mean and the variance of the fixed effect estimator of the linear model are affected by the results of LS-VCE. Various examples are given to illustrate the theory.","Least-squares variance component estimation (LS-VCE); Elliptically contoured distribution; Best linear unbiased estimator (BLUE); Best invariant quadratic unbiased estimator (BIQUE); Minimum norm quadratic unbiased estimator (MINQUE); Restricted maximum likelihood estimator (REML)","en","journal article","Springer","","","","","","","","Aerospace Engineering","Delft Institute of Earth Observation and Space Systems (DEOS)","","","",""
"uuid:5f736e2f-f029-4a2e-9c42-25b5fff4f622","http://resolver.tudelft.nl/uuid:5f736e2f-f029-4a2e-9c42-25b5fff4f622","Building the fastest bicycle in the world; a year with the Human Power Team Delft & Amsterdam","Schuurman, M.; Roks, G.","","2014","“Third time lucky” is the saying, but for the third Human Power Team it almost turned out as a year for nothing. The team has been attempting to set the world record for the fastest bicycle powered only by human muscles for two years already. This endeavor to let a Dutchman be the fastest human on earth resulted in a marvelous year with many ups and downs and a world record.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2afbd85e-4f71-4b34-9f57-86fa6ab3fae5","http://resolver.tudelft.nl/uuid:2afbd85e-4f71-4b34-9f57-86fa6ab3fae5","Pressure estimation from single-snapshot tomographic PIV in a turbulent boundary layer","Schneiders, J.F.G.; Pröbsting, S.; Dwight, R.P.; Van Oudheusden, B.W.; Scarano, F.","","2016","A method is proposed to determine the instantaneous pressure field from a single tomographic PIV velocity snapshot and is applied to a flat-plate turbulent boundary layer. The main concept behind the single-snapshot pressure evaluation method is to approximate the flow acceleration using the vorticity transport equation. The vorticity field calculated from the measured instantaneous velocity is advanced over a single integration time step using the vortex-in-cell (VIC) technique to update the vorticity field, after which the temporal derivative and material derivative of velocity are evaluated. The pressure in the measurement volume is subsequently evaluated by solving a Poisson equation. The procedure is validated considering data from a turbulent boundary layer experiment, obtained with time-resolved tomographic PIV at 10 kHz, where an independent surface pressure fluctuation measurement is made by a microphone. The cross-correlation coefficient of the surface pressure fluctuations calculated by the single-snapshot pressure method with respect to the microphone measurements is calculated and compared to that obtained using time-resolved pressure-from-PIV, which is regarded as benchmark. The single-snapshot procedure returns a cross-correlation comparable to the best result obtained by time-resolved PIV, which uses a nine-point time kernel. When the kernel of the time-resolved approach is reduced to three measurements, the single-snapshot method yields approximately 30 % higher correlation. Use of the method should be cautioned when the contributions to fluctuating pressure from outside the measurement volume are significant. The study illustrates the potential for simplifying the hardware configurations (e.g. high-speed PIV or dual PIV) required to determine instantaneous pressure from tomographic PIV.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:15d83310-ac7a-46b9-a1d5-adb6a5931651","http://resolver.tudelft.nl/uuid:15d83310-ac7a-46b9-a1d5-adb6a5931651","Infrasonic signature of the 2009 major sudden stratospheric warming","Evers, L.G.; Siegmund, P.","","2009","The study of infrasound is experiencing a renaissance since it was chosen as a verification technique for the Comprehensive Nuclear-Test-Ban Treaty. The success of the verification technique strongly depends on knowledge of upper atmospheric processes. The ability of infrasound to probe the upper atmosphere starts to be exploited, taking the field beyond its monitoring application. Processes in the stratosphere couple to the troposphere and influence our daily weather and climate. Infrasound delivers actual observations on the state of the stratosphere with a high spatial and temporal resolution. Here we show the infrasonic signature, passively obtained, of a drastic change in the stratosphere due to the major sudden stratospheric warming (SSW) of January 2009. With this study, we infer the enormous capacity of infrasound in acoustic remote sensing of stratospheric processes on a global scale with surface based instruments.","infrasound; sudden stratospheric warming; microbaroms","en","journal article","American Geophysical Union","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:31e16a3f-ab40-4bae-8086-5329d2d82308","http://resolver.tudelft.nl/uuid:31e16a3f-ab40-4bae-8086-5329d2d82308","ADOP in closed form for a hierarchy of multi-frequency single-baseline GNSS models","Odijk, D.; Teunissen, P.J.G.","","2008","Successful carrier phase ambiguity resolution is the key to high-precision positioning with Global Navigation Satellite Systems (GNSS). The ambiguity dilution of precision (ADOP) is a well-known scalar measure which can be used to infer the strength of the GNSS model for carrier phase ambiguity resolution. In this contribution we present analytical closed-form expressions for the ADOP. This will be done for a whole class of different multi- frequency single baseline models. These models include the geometry-fixed, the geometry-free and the geometry-based models, respectively. And within the class of geometry-based models, we discriminate between short and long observation time spans, and between stationary and moving receivers. The easy-to-use ADOP expressions can be applied to infer the contribution of various GNSS model factors. They comprise, for instance, the type, the number and the precision of the GNSS observations, the number and selection of frequencies, the presence of atmospheric disturbances, the length of the observation time span and the length of the baseline.","ADOP; GNSS; GPS; Ambiguity resolution","en","journal article","Springer","","","","","","","","Aerospace Engineering","Delft Institute of earth Observation and Space Systems (DEOS)","","","",""
"uuid:08d5d3d5-a946-4f59-b5d8-ec7ed3b3658b","http://resolver.tudelft.nl/uuid:08d5d3d5-a946-4f59-b5d8-ec7ed3b3658b","Experimental and Numerical Investigation of Metal Type and Thickness Effects on the Impact Resistance of Fiber Metal Laminates","Sadighi, M.; Pärnänen, T.; Alderliesten, R.C.; Sayeaftabi, M.; Benedictus, R.","","2012","The impact response of fiber metal laminates (FMLs), has been investigated with experiments and numerical simulations, which is reported in this article. Low-velocity impacts were carried out to study the effects of metal type and thickness within FMLs. Glare5-3/2 laminates with two aluminum layer thicknesses and a similar FML containing magnesium sheets were impacted by drop weight tests. Also, a major part of this study was to accomplish a dynamic non-linear transient analysis to study the impact response of FMLs using the commercial finite element (FE) analysis code ABAQUS. By reviewing different approaches of modeling constituents of an FML, it is shown that the appropriate selection of elements hasmore significant role than failure criterion to predict acceptable results for this type of laminate and loading. The good agreement obtained between experimental and numerical results verifies the possibility of relatively simpler simulation by FE-analysis to predict overall response of FMLs under impact loading.","fiber metal laminates; magnesium; low velocity impact; numerical modeling; abaqus","en","journal article","Springer-Verlag","","","","","","","","Aerospace Engineering","Aerspace Structures and Materials","","","",""
"uuid:40251492-8b43-4553-bae5-9f036203fde4","http://resolver.tudelft.nl/uuid:40251492-8b43-4553-bae5-9f036203fde4","Modeling and characterization of dielectrophoretically structured piezoelectric composites using piezoceramic particle inclusions with high aspect ratios + Erratum","Van den Ende, D.A.; Maier, R.A.; Van Neer, P.L.M.J.; Van der Zwaag, S.; Randall, C.A.; Groen, W.A.","","2013","In this work, the piezoelectric properties at high electric fields of dielectrophoretically aligned PZT—polymer composites containing high aspect ratio particles (such as short fibers) are presented. Polarization and strain as a function of electric field are evaluated. The properties of the composites are compared to those of PZT-polymer composites with equiaxed particles, continuous PZT fiber-polymer composites, and bulk PZT ceramics. From high-field polarization and strain measurements, the effective field dependent permittivity and piezoelectric charge constant in the poling direction are determined for dielectrophoresis structured PZT-polymer composites, continuous PZT fiber-polymer composites, and bulk PZT ceramics. The changes in dielectric properties of the inclusions and the matrix at high fields influence the dielectric and piezoelectric properties of the composites. It is found that the permittivity and piezoelectric charge constants increase towards a maximum at an applied field of around 2.5-5?kV/mm. The electric field at which the maximum occurs depends on the aspect ratio and degree of alignment of the inclusions. Experimental values of d33 at low and high applied fields are compared to a model describing the composites as a continuous polymer matrix containing PZT particles of various aspect ratios arranged into chains. Thickness mode coupling factors were determined from measured impedance data using fitted equivalent circuit model simulations. The relatively high piezoelectric strain constants, voltage constants, and thickness coupling factors indicate that such aligned short fiber composites could be useful as flexible large area transducers. Erratum published 5 March 2015: http://dx.doi.org/10.1063/1.4914113","dielectric polarisation; inclusions; lead compounds; organic-inorganic hybrid materials; permittivity; piezoceramics; piezoelecticity; polymers","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:14ac2c0b-b04e-4845-929d-43d10ad86b1f","http://resolver.tudelft.nl/uuid:14ac2c0b-b04e-4845-929d-43d10ad86b1f","Solenoidal filtering of volumetric velocity measurements using Gaussian process regression","Azijli, I.; Dwight, R.P.","","2015","Volumetric velocity measurements of incompressible flows contain spurious divergence due to measurement noise, despite mass conservation dictating that the velocity field must be divergence-free (solenoidal). We investigate the use of Gaussian process regression to filter spurious divergence, returning analytically solenoidal velocity fields. We denote the filter solenoidal Gaussian process regression (SGPR) and formulate it within the Bayesian framework to allow a natural inclusion of measurement uncertainty. To enable efficient handling of large data sets on regular and near-regular grids, we propose a solution procedure that exploits the Toeplitz structure of the system matrix. We apply SGPR to two synthetic and two experimental test cases and compare it with two other recently proposed solenoidal filters. For the synthetic test cases, we find that SGPR consistently returns more accurate velocity, vorticity and pressure fields. From the experimental test cases, we draw two important conclusions. Firstly, it is found that including an accurate model for the local measurement uncertainty further improves the accuracy of the velocity field reconstructed with SGPR. Secondly, it is found that all solenoidal filters result in an improved reconstruction of the pressure field, as verified with microphone measurements. The results obtained with SGPR are insensitive to correlation length, demonstrating the robustness of the filter to its parameters.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:4b1c6a9f-2d0e-4a85-a008-7fb21ebcd8ce","http://resolver.tudelft.nl/uuid:4b1c6a9f-2d0e-4a85-a008-7fb21ebcd8ce","Design synthesis exercise 2011","Melkert, J.A.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2c764fac-e7e9-4621-87d6-3cc072685b0a","http://resolver.tudelft.nl/uuid:2c764fac-e7e9-4621-87d6-3cc072685b0a","ICESat Full-Waveform Altimetry Compared to Airborne Laser Scanning Altimetry Over The Netherlands","Duong, H.; Lindenbergh, R.; Pfeifer, N.; Vosselman, G.","","2009","Since 2003, the full-waveform laser altimetry system onboard NASA's Ice, Cloud and land Elevation Satellite (ICESat) has acquired a worldwide elevation database. ICESat data are widely applied for change detection of ice sheet mass balance, forest structure estimation, and digital terrain model generation of remote areas. ICESat's measurements will be continued by a follow-up mission. To fully assess the application possibilities of the full-waveform products of these missions, this research analyzes the vertical accuracy of ICESat products over complex terrain with respect to land cover type. For remote areas, validation of individual laser shots is often beyond reach. For a country with extensive geo-infrastructure such as The Netherlands, excellent countrywide validation is possible. Therefore, the ICESat full-waveform product GLA01 and the land elevation product GLA14 are compared to data from the Dutch airborne laser altimetry archive Actual Height model of the Netherlands (AHN). For a total population of 3172 waveforms, differences between ICESat- and AHN-derived terrain heights are determined. The average differences are below 25 cm over bare land and urban areas. Over forests, differences are even smaller but with slightly larger standard deviations of about 60 cm. Moreover, a waveform-based feature height comparison resulted in feature height differences of 1.89 m over forest, 1.48 m over urban areas, and 29 cm over low vegetation. These results, in combination with the presented processing chain and individual waveform examples, show that state-of-the-art ICESat waveform processing is able to analyze waveforms at the individual shot level, particularly outside urban areas.","actual height model of The Netherlands (AHN); digital terrain models (DTMs); feature height; full waveform; Ice, Cloud and land Elevation Satellite (ICESat); laser altimetry","en","journal article","IEEE","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:d2133a54-2ed2-4d86-9e4b-3de4d2136194","http://resolver.tudelft.nl/uuid:d2133a54-2ed2-4d86-9e4b-3de4d2136194","The sum of all knowledge; bringing experiment and simulation together","Dwight, R.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ee4a6800-ba97-4249-ad81-6f7d58f0c721","http://resolver.tudelft.nl/uuid:ee4a6800-ba97-4249-ad81-6f7d58f0c721","The hunt for infrasound; infrasound detections can be used to locate infrasound sources, such as volcanoes, supersonic jet fighters and (nuclear) explosions","Briels, S.; Evers, L.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:34d18bb2-62c3-45ed-9801-d950314c1a04","http://resolver.tudelft.nl/uuid:34d18bb2-62c3-45ed-9801-d950314c1a04","The innovative shepherd; an interview with Professor Sybrand van der Zwaag","Wamiti, L.; Broekhuizen, B.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4e38b54f-8132-413e-8a1a-9b340bb11d0c","http://resolver.tudelft.nl/uuid:4e38b54f-8132-413e-8a1a-9b340bb11d0c","Opposite hemispheric asymmetries during the ionospheric storm of 29–31 August 2004","Astafyeva, E.; Zakharenkova, I.; Doornbos, E.N.","","2015","By making use of multiple ground-based and spaceborne instruments, we study ionospheric and thermospheric behavior during the moderately intense geomagnetic storm of 29–31 August 2004 (minimum Dst excursion of ?128?nT). Although this storm was far from the strongest in solar cycle 23, it provoked quite interesting effects in the ionosphere, such as opposite hemispheric asymmetries in the ionospheric F layer and in the topside ionosphere and a development of the ionospheric superfountain effect in the postsunset sector. Data from ground-based GPS receivers and ionosondes revealed large increase in total electron content (TEC) and in NmF2 in the southern hemisphere, whereas in the northern hemisphere, very weak or no effect was observed. On the contrary, the topside measurements indicated the occurrence of a positive storm in the northern hemisphere. Overall, the strongest storm time disturbances were observed in the postsunset sector (~20:30–21:30 LT), where satellite radar altimeters TOPEX and Jason 1, along with the CHAMP satellite showed ~250–400% TEC increase in the middle- and low-latitude regions. The signatures of the ionospheric plasma enhancement were seen up to the height of the Defense Meteorological Satellite Program (DMSP) satellites (~840?km). As for the thermospheric storm, data of the Gravity Recovery and Climate Experiment (GRACE) satellite mission revealed no asymmetry in neutral density data in the evening sector (~17 UT); however, very strong hemispheric asymmetry was observed in the postsunset sector by CHAMP (~21 UT). Overall, neutral density increase in the postsunset sector was found to be much stronger than in the evening sector.","ionospheric storm; hemispheric asymmetry; topside contribution; superfountain effect; thermospheric storm; postsunset sector","en","journal article","American Geophysical Union","","","","","","","2015-07-21","Aerospace Engineering","Space Engineering","","","",""
"uuid:7fc89d78-a9e1-4f5f-9e26-92daa98e4f91","http://resolver.tudelft.nl/uuid:7fc89d78-a9e1-4f5f-9e26-92daa98e4f91","Accuracy assessment of the monthly GRACE geoids based upon a simulation","Schrama, E.J.O.; Visser, P.N.A.M.","","2007","","Temporal gravity; Hydrology; Ocean bottom pressure; Tides; Air pressure; GRACE; GPS","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1a32d601-717c-465a-b81d-c9ac72b4c47b","http://resolver.tudelft.nl/uuid:1a32d601-717c-465a-b81d-c9ac72b4c47b","A commercial spaceflight evangelist; an interview with space tourist Anousheh Ansari","Van Gent, I.; Dekker, S.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:57a2f9c9-c91f-4150-a0ce-2ada4205ba19","http://resolver.tudelft.nl/uuid:57a2f9c9-c91f-4150-a0ce-2ada4205ba19","Flight forward, the future of air transportation; VSV ""Leonardo da Vinci"" symposium; Delft, March 26th, 2010","Dekker, S.; De Graaf, M.; Van Houten, D.; Van Ettinger, A.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:cb1479c3-cad6-4525-981e-df3a99af82bb","http://resolver.tudelft.nl/uuid:cb1479c3-cad6-4525-981e-df3a99af82bb","Three dimensional experimental investigation of a hypersonic double-ramp flow","Schrijer, F.F.J.; Caljouw, R.; Scarano, F.; Van Oudheusden, B.W.","","","The flow over a 15?-45? double compression ramp was studied at Mach 7.5. CFD computations are compared to 2 component PIV (particle image velocimetry) measurements. Furthermore stereoscopic PIV was used to measure the three component velocity vector, enabling to perform a 3D flow survey. The overall flow topology is assessed and special attention is devoted to the separated region. Finally the effect of a sharp leading edge on the separation region is investigated.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:e70aa707-3122-40ef-aa21-aee3f11b53d3","http://resolver.tudelft.nl/uuid:e70aa707-3122-40ef-aa21-aee3f11b53d3","Optimization of multiplane ?PIV for wall shear stress and wall topography characterization","Rossi, M.; Lindken, R.; Westerweel, J.","","2009","Multiplane ?PIV can be utilized to determine the wall shear stress and wall topology from the measured flow over a structured surface. A theoretical model was developed to predict the measurement error for the surface topography and shear stress, based on a theoretical analysis of the precision in PIV measurements. The main parameters that affect the accuracy of the measurement are identified. The effect of different parameter settings is studied by means of Monte Carlo simulations, and the results are compared with an experimental test case. The results are used to determine the recommended parameter settings for this measurement approach.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Process and Energy","","","",""
"uuid:1c6f6e55-7f3c-475b-a67b-7702fb487f50","http://resolver.tudelft.nl/uuid:1c6f6e55-7f3c-475b-a67b-7702fb487f50","Integer least-squares theory for the GNSS compass","Teunissen, P.J.G.","","2010","Global navigation satellite system (GNSS) carrier phase integer ambiguity resolution is the key to highprecision positioning and attitude determination. In this contribution, we develop new integer least-squares (ILS) theory for the GNSS compass model, together with efficient integer search strategies. It extends current unconstrained ILS theory to the nonlinearly constrained case, an extension that is particularly suited for precise attitude determination. As opposed to current practice, our method does proper justice to the a priori given information. The nonlinear baseline constraint is fully integrated into the ambiguity objective function, thereby receiving a proper weighting in its minimization and providing guidance for the integer search. Different search strategies are developed to compute exact and approximate solutions of the nonlinear constrained ILS problem. Their applicability depends on the strength of the GNSS model and on the length of the baseline. Two of the presented search strategies, a global and a local one, are based on the use of an ellipsoidal search space. This has the advantage that standard methods can be applied. The global ellipsoidal search strategy is applicable to GNSS models of sufficient strength, while the local ellipsoidal search strategy is applicable tomodels for which the baseline lengths are not too small. We also develop search strategies for the most challenging case, namely when the curvature of the non-ellipsoidal ambiguity search space needs to be taken into account. Two such strategies are presented, an approximate one and a rigorous, somewhat more complex, one. The approximate one is applicable when the fixed baseline variance matrix is close to diagonal. Both methods make use of a search and shrink strategy. The rigorous solution is efficiently obtained by means of a search and shrink strategy that uses nonquadratic, but easy-to-evaluate, bounding functions of the ambiguity objective function. The theory presented is generally valid and it is not restricted to any particular GNSS or combination of GNSSs. Its general applicability also applies to the measurement scenarios (e.g. single-epoch vs. multiepoch, or single-frequency vs. multi-frequency). In particular it is applicable to the most challenging case of unaided, single frequency, single epoch GNSS attitude determination. The success rate performance of the different methods is also illustrated.","GNSS; Attitude determination; Integer ambiguity resolution; Constrained integer least squares","en","journal article","Springer","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:07fc2767-47df-41ac-8fe6-d4a4ca1ae83e","http://resolver.tudelft.nl/uuid:07fc2767-47df-41ac-8fe6-d4a4ca1ae83e","Intraannual variability of tides in the thermosphere from model simulations and in situ satellite observations","Häusler, K.; Hagan, M.E.; Forbes, J.M.; Zhang, X.; Doornbos, E.; Bruinsma, S.; Lu, G.","","2015","In this paper, we provide insights into limitations imposed by current satellite-based strategies to delineate tidal variability in the thermosphere, as well as the ability of a state-of-the-art model to replicate thermospheric tidal determinations. Toward this end, we conducted a year-long thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM) simulation for 2009, which is characterized by low solar and geomagnetic activity. In order to account for tropospheric waves and tides propagating upward into the ?30–400 km model domain, we used 3-hourly MERRA (Modern-Era Retrospective Analysis for Research and Application) reanalysis data. We focus on exospheric tidal temperatures, which are also compared with 72 day mean determinations from combined Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellite observations to assess the model's capability to capture the observed tidal signatures and to quantify the uncertainties associated with the satellite exospheric temperature determination technique. We found strong day-to-day tidal variability in TIME-GCM that is smoothed out when averaged over as few as ten days. TIME-GCM notably overestimates the 72 day mean eastward propagating tides observed by CHAMP/GRACE, while capturing many of the salient features of other tidal components. However, the CHAMP/GRACE tidal determination technique only provides a gross climatological representation, underestimates the majority of the tidal components in the climatological spectrum, and moreover fails to characterize the extreme variability that drives the dynamics and electrodynamics of the ionosphere-thermosphere system. A multisatellite mission that samples at least six local times simultaneously is needed to provide this quantification.","","en","journal article","American Geophysical Union","","","","","","","2015-07-24","Aerospace Engineering","Space Engineering","","","",""
"uuid:a57229fb-cb5f-4a21-a8d7-4fca6b477506","http://resolver.tudelft.nl/uuid:a57229fb-cb5f-4a21-a8d7-4fca6b477506","Missions to Mars: MSL and Mars 2020; interview with AE alumnus Gerhard Kruizinga working at JPL","Wink, J.; Roos, B.; Gupta, S.","","2013","The Jet Propulsion Laboratory (JPL) located in Pasadena, California is the leading organisation for planetary missions and a point of attraction for many Aerospace Engineers. The Leonardo Times interviewed a former student of our faculty who made the big leap overseas and dedicated his career to planetary exploration from JPL. We talk to him about his job, current and future Mars projects he is involved in.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:94aa3ce8-bd4b-4674-9801-c059328676bd","http://resolver.tudelft.nl/uuid:94aa3ce8-bd4b-4674-9801-c059328676bd","Brilliance at aerodynamics; an interview with professor Hester Bijl","Van Gent, I.; Schneiders, J.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b2e6e3d0-2aec-479d-a91f-9621939b436f","http://resolver.tudelft.nl/uuid:b2e6e3d0-2aec-479d-a91f-9621939b436f","Wind load effect in topology optimization problems","Zakhama, R.; Abdalla, M.M.; Gürdal, Z.; Smaoui, H.","","2007","","","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b12833bc-1f47-4ef8-a198-a87d35a81d6a","http://resolver.tudelft.nl/uuid:b12833bc-1f47-4ef8-a198-a87d35a81d6a","Investigation of higher spanwise Helmholtz resonance modes in slender covered cavities","De Jong, A.T.; Bijl, H.","","2010","Cavity aeroacoustic noise is relevant for aerospace and automotive industries and widely investigated since the 1950s. Most investigations so far consider cavities where opening length and width are of similar scale. The present investigation focuses on a less investigated setup, namely cavities that resemble the door gaps of automobiles. These cavities are both slender (width much greater than length or depth) and partially covered. Furthermore they are under influence of a low Mach number flow with a relatively thick boundary layer. Under certain conditions, these gaps can produce tonal noise. The present investigation attempts to reveal the aeroacoustic mechanism of this tonal noise for higher resonance modes. Experiments have been conducted on a simplified geometry, where unsteady internal pressures have been measured at different spanwise locations. With increasing velocity, several resonance modes occur. In order to obtain higher mode shapes, the cavity acoustic response is simulated and compared with experiment. Using the frequency-filtered simulation pressure field, the higher modes shapes are retrieved. The mode shapes can be interpreted as the slender cavity self-organizing into separate Helmholtz resonators that interact with each other. Based on this, an analytical model is derived that shows good agreement with the simulations and experimental results.","acoustic noise; acoustic resonance; aeroacoustics; aerospace industry; automobile industry","en","journal article","Acoustical Society of America","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:1322cbd5-09ce-4233-ad12-6c851cda726c","http://resolver.tudelft.nl/uuid:1322cbd5-09ce-4233-ad12-6c851cda726c","Dielectrophoretically structured piezoelectric composites with high aspect ratio piezoelectric particles inclusions","Van den Ende, D.A.; Van Kempen, S.E.; Wu, X.; Groen, W.A.; Randall, C.A.; Van der Zwaag, S.","","2012","Piezoelectric composites were prepared by dielectrophoretic alignment of high aspect ratio piezoelectric particles in a thermosetting polymer matrix. A high level of alignment was achieved in the cured composite from a resin containing randomly oriented high aspect ratio particles. Upon application of an electric field during curing of the resin, the particles were found to rotate with their long axes in the direction of the electric field, before coalescing to form chains. The dielectric and piezoelectric properties of the structured composites are well described by an analytical model for composites containing particles arranged into chains. The influence of degree of rotation and aspect ratio of the individual particles as well as their spacing is described with this model. The results correlate with the experimental values for both permittivity and piezoelectric constants in the poling direction. Dielectric and piezoelectric properties were significantly improved with respect to randomly dispersed piezoelectric ceramic powder–polymer composites and the maximum g33 was shifted to a lower volume fraction. The results could have implications for development of dielectric and piezoelectric (nano-)fiber composites for dielectrics such as embedded capcitors, as well as piezoelectrics for sensing and energy harvesting applications.","curing; dielectric polarisation; filled polymers; inclusions; lead compounds; particle reinforced composites; permittivity; piezoceramics; piezoelectricity; powders; resins","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:41a6edc9-08d8-4190-9f00-cde6f7f4ac7f","http://resolver.tudelft.nl/uuid:41a6edc9-08d8-4190-9f00-cde6f7f4ac7f","On Closing the Streamwise BiGlobal Stability Problem: The Effect of Boundary Conditions","Groot, K.J.; Pinna, F.; Van Oudheusden, B.W.","","2015","The modal streamwise BiGlobal stability approach introduces problems regarding the specification of in- and outflow boundary conditions (BCs). Several conditions linked to lower hierarchical stability frameworks are elaborated and are applied to a freestream and boundary layer flow. The former case is used to demonstrate the odd-even decoupling of the spectrum with the streamwise node number. The latter case illustrates that the spatial growth varies widely with different BCs, while specific Robin BCs yield the largest amplification near a target frequency. Combined, the cases show that the spectra might vary widely while corresponding to very similar spatial growth characteristics and vice versa.","linear stability; BiGlobal; non-parallel; boundary closure","en","journal article","Elsevier","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:59e9520c-bfc3-4335-9da4-cdcf4d525d9e","http://resolver.tudelft.nl/uuid:59e9520c-bfc3-4335-9da4-cdcf4d525d9e","Pressure actuated cellular structures; a novel concept for morphing structures inspired by plants","Pagitz, M.; Coosemans, J.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d3fcce1a-0578-41ce-a661-0245b8ddfc66","http://resolver.tudelft.nl/uuid:d3fcce1a-0578-41ce-a661-0245b8ddfc66","Aircraft tooling and the automated equipment; internship at Electroimpact, Seattle USA","Van der Sman, E.","","2013","If we consider the enormous amount of parts that are necessary to build a commercial aircraft, it becomes clear that assembling all parts with great accuracy is a challenge. The development of new tooling solutions and automated equipment for the manufacturing of commercial and military aircraft is therefore of great importance. The increasing use of robots results in faster, safer, less expensive and more precise manufacturing processes.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e55b57a6-31ee-4325-951f-3686ae062531","http://resolver.tudelft.nl/uuid:e55b57a6-31ee-4325-951f-3686ae062531","Bayesian inference for data assimilation using least-squares finite element methods","Dwight, R.P.","","2010","It has recently been observed that Least-Squares Finite Element methods (LS-FEMs) can be used to assimilate experimental data into approximations of PDEs in a natural way, as shown by Heyes et al. in the case of incompressible Navier Stokes ow [1]. The approach was shown to be effective without regularization terms, and can handle substantial noise in the experimental data without filtering. Of great practical importance is that { unlike other data assimilation techniques { it is not signifcantly more expensive than a single physical simulation. However the method as presented so far in the literature is not set in the context of an inverse problem framework, so that for example the meaning of the final result is unclear. In this paper it is shown that the method can be interpreted as finding a maximum a posteriori (MAP) estimator in a Bayesian approach to data assimilation, with normally distributed observational noise, and a Bayesian prior based on an appropriate norm of the governing equations. In this setting the method may be seen to have several desirable properties: most importantly discretization and modelling error in the simulation code does not affect the solution in limit of complete experimental information, so these errors do not have to be modelled statistically. Also the Bayesian interpretation better justifies the choice of the method, and some useful generalizations become apparent. The technique is applied to incompressible Navier-Stokes flow in a pipe with added velocity data, where its effectiveness, robustness to noise, and application to inverse problems is demonstrated.","","en","journal article","Institute of Physics","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f1d040ef-68de-4adb-8790-3b65e4ac666a","http://resolver.tudelft.nl/uuid:f1d040ef-68de-4adb-8790-3b65e4ac666a","Ambassadors of humankind; making a mark in the vast expanse of space","Broekhuizen, B.","","2013","It almost sounds like a riddle: man-made objects travelling at speeds in excess of ten kilometres per second at a distance of many billions of kilometres. These are the man-made objects that are farthest away and, in a way, they serve as ambassadors of humankind. Each object was launched in the seventies and carries with it a symbol to signify humanity’s achievements: they are Pioneer 10 and 11, and Voyager 1 and 2.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ae6023d8-477d-46a9-8b62-67d2c4eac840","http://resolver.tudelft.nl/uuid:ae6023d8-477d-46a9-8b62-67d2c4eac840","The S-vision concept; SSVOBB Lambach Aircrafts' new ambition","Decloedt, D.","","2011","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:285ee260-4d50-417c-83ea-cf9a862bbbf0","http://resolver.tudelft.nl/uuid:285ee260-4d50-417c-83ea-cf9a862bbbf0","Localized spectral analysis of global satellite gravity fields for recovering time-variable mass redistributions","Han, S.C.; Ditmar, P.","","2007","A spatiospectral localization method is discussed for processing the global geopotential coefficients from satellite mission data to investigate time-variable gravity. The time-variable mass variation signal usually appears associated with a particular geographical area yielding inherently regional structure, while the dependence of the satellite gravity errors on a geographical region is not so evident. The proposed localization amplifies the signal-to-noise ratio of the (non-stationary) time-variable signals in the geopotential coefficient estimates by localizing the global coefficients to the area where the signal is expected to be largest. The results based on localization of the global satellite gravity coefficients such as Gravity Recovery And Climate Experiment (GRACE) and Gravity and Ocean Circulation Explorer (GOCE) indicate that the coseismic deformation caused by great earthquakes such as the 2004 Sumatra–Andaman earthquake can be detected by the low-low tracking and the gradiometer data within the bandwidths of spherical degrees 15–30 and 25–100, respectively. However, the detection of terrestrial water storage variation by GOCE gradiometer is equivocal even after localization.","Spatiospectral localization; Spherical harmonic analysis; GRACE; GOCE; Hydrology; Earthquake","en","journal article","Springer","","","","","","","","Aerospace Engineering","Department of Earth Observation and Space Systems","","","",""
"uuid:72170533-c427-4308-8edc-bebe3fe07ab1","http://resolver.tudelft.nl/uuid:72170533-c427-4308-8edc-bebe3fe07ab1","The Sukhoi T-50; the new fifth generation fighter aircraft, the PAK-FA project","Bavelaar, E.; Van Veen, L.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:afa18115-4bde-4534-9ba5-a20b86c0817a","http://resolver.tudelft.nl/uuid:afa18115-4bde-4534-9ba5-a20b86c0817a","Impact of Galileo on global ionosphere map estimation","Le, A.Q.","","2006","","","en","journal article","Cambridge University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:df9257fb-9590-4918-bf03-d8d05ecd6f4a","http://resolver.tudelft.nl/uuid:df9257fb-9590-4918-bf03-d8d05ecd6f4a","Eco-runner team Delft; the most fuel efficient vehicle in the world","Rijks, F.","","2014","The slogan, ‘Eco-Runner: the most fuel efficient vehicle in the world’ of the Eco-Runner Team Delft says it all: designing and building the most fuel efficient vehicle in the world. The Eco-Runner Team is a ‘D:DREAM Team’ where students from various faculties work together to design and build extremely efficient, hydrogen powered vehicles and conduct research in the fields of aerodynamics, structures, electronics, hydrogen fuel cells and driving strategies.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:20e4c010-35f6-42ba-8be1-2fc260fea7e6","http://resolver.tudelft.nl/uuid:20e4c010-35f6-42ba-8be1-2fc260fea7e6","Agent-based modeling and simulation of emergent behavior in air transportation","Bouarfa, S.; Blom, H.A.P.; Curran, R.; Everdij, M.H.C.","","2013","Purpose Commercial aviation is feasible thanks to the complex socio-technical air transportation system, which involves interactions between human operators, technical systems, and procedures. In view of the expected growth in commercial aviation, significant changes in this socio-technical system are in development both in the USA and Europe. Such a complex socio-technical system may generate various types of emergent behavior, which may range from simple emergence, through weak emergence, up to strong emergence. The purpose of this paper is to demonstrate that agent-based modeling and simulation allows identifying changed and novel rare emergent behavior in this complex socio-technical system. Methods An agent based model of a specific operation at an airport has been developed. The specific operation considered is the controlled crossing by a taxiing aircraft of a runway that is in use for controlled departures. The agent-based model includes all relevant human and technical agents, such as the aircraft, the pilots, the controllers and the decision support systems involved. This agent-based model is used to conduct rare event Monte Carlo (MC) simulations. Results The MC simulation results obtained confirm that agent based modeling and simulation of a socio-technical air transportation system allows to identify rare emergent behavior that was not identified through earlier, non-agent-based simulations, including human-in-the-loop simulations of the same operation. A typical example of such emergent behavior is the finding that alerting systems do not really reduce the safety risk. Conclusions Agent based MC simulations of commercial aviation operations has been demonstrated as a viable way to be evaluated regarding rare emergent behaviour. This rare emergent behaviour could not have been found through the more traditional simulation approaches.","agent-based modeling and simulation; complex socio-technical systems; air transportation; airport operations; safety risk analysis","en","journal article","","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:1e9a9f27-7384-40f9-8ca3-d08ed908283f","http://resolver.tudelft.nl/uuid:1e9a9f27-7384-40f9-8ca3-d08ed908283f","Goal-Oriented Error Estimation and Adaptivity for Free-Boundary Problems: The Shape-Linearization Approach","Van der Zee, K.G.; Van Brummelen, E.H.; De Borst, R.","","2010","We develop duality-based a posteriori error estimates for functional outputs of solutions of free-boundary problems via shape-linearization principles. To derive an appropriate dual (linearized adjoint) problem, we linearize the domain dependence of the very weak form and goal functional of interest using techniques from shape calculus. We show for a Bernoulli-type free-boundary problem that the dual problem corresponds to a Poisson problem with a Robin-type boundary condition involving the curvature. Moreover, we derive a generalization of the dual problem for nonsmooth free boundaries which includes a natural extension of the curvature term. The effectivity of the dual-based error estimate and its usefulness in goal-oriented adaptive mesh refinement is demonstrated by numerical experiments.","goal-oriented error estimation; a posteriori error estimation; Bernoulli free-boundary problem; shape derivative; shape differential calculus; linearized adjoint; adaptive mesh refinement","en","journal article","Society for Industrial and Applied Mathematics","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:fd758d2b-cd61-436b-b75e-a076d6eb9363","http://resolver.tudelft.nl/uuid:fd758d2b-cd61-436b-b75e-a076d6eb9363","Modeling particulate self-healing materials and application to uni-axial compression","Herbst, O.; Luding, S.","","2008","Using an advanced history dependent contact model for DEM simulations, including elasto-plasticity, viscosity, adhesion, and friction, pressure-sintered tablets are formed from primary particles. These tablets are subjected to unconfined uni-axial compression until and beyond failure. For fast and slow deformation we observe ductile-like and brittle softening, respectively. We propose a model for local self-healing that allows damage to heal during loading such that the material strength of the sample increases and failure/softening is delayed to larger strains. Local healing is achieved by increasing the (attractive) contact adhesion forces for those particles involved in a potentially breaking contact. We examine the dependence of the strength of the material on (a) the damage detection sensitivity, (b) the damage detection rate, and (c) the (increased) adhesion between healed contacts. The material strength is enhanced, i.e., the material fails at larger strains and reaches larger maximal stress values, when any of the parameters (a)-(c) is increased. For very large adhesion between the healed contacts an interesting instability with strong (brittle) fluctuations of the healed material's strength is observed.","numerical simulations; composite-materials; shear deformation; granular media; polymer; repair; continuum; dynamics; spheres; impact","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:70d80827-8f89-48bc-9e61-f382fc316181","http://resolver.tudelft.nl/uuid:70d80827-8f89-48bc-9e61-f382fc316181","Energy integral method for gravity field determination from satellite orbit coordinates","Visser, P.N.A.M.; Sneeuw, N.; Gerlach, C.","","2003","A fast iterative method for gravity field determination from low Earth satellite orbit coordinates has been developed and implemented successfully. The method is based on energy conservation and avoids problems related to orbit dynamics and initial state. In addition, the particular geometry of a repeat orbit is exploited by using a very efficient iterative estimation scheme, in which a set of normal equations is approximated by a sparse block-diagonal equivalent. Recovery experiments for spherical harmonic gravity field models up to degree and order 80 and 120 were conducted based on a 29-day simulated data set of orbit coordinates. The method was found to be very flexible and could be easily adapted to include observations of non-conservative accelerations, such as (to be) provided by satellites like CHAMP, GRACE, and GOCE. A serious drawback of the method is its large sensitivity to satellite velocity errors. Existing orbit determination strategies need to be altered or augmented to include algorithms that focus on optimizing the accuracy of estimated velocities.","energy integral; gravity field determination; accelerometer observations; block-diagonal matrix; orbit errors; orbit coordinates","en","journal article","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:36a6086e-ced5-4396-8161-42e50a775a9e","http://resolver.tudelft.nl/uuid:36a6086e-ced5-4396-8161-42e50a775a9e","Three-dimensional evolution of flow structures in transitional circular and chevron jets","Violato, D.; Scarano, F.","","2011","The three-dimensional behavior of flow transition in circular and 6-chevron jets at Re?=?5000 is investigated with experiments conducted on a free water jet by time-resolved tomographic particle image velocimetry. The emphasis is on the unsteady organization of coherent flow structures, which play a role in the generation of acoustic noise. Shedding and pairing of vortices are the most pronounced phenomena observed in the near field of the circular jet. The first and second pairing amplify the axial pulsatile motion in the jet column and lead to the growth of azimuthal waves culminating in the breakup of the vortex ring. Streamwise vortices of axial and radial vorticity are observed in the outer region and move inward and outward under the effect of the vortex rings. In the jet with chevrons, the axisymmetric ring-like coherence of the circular jet is not encountered. Instead, streamwise flow structures of azimuthal vorticity emanate from the chevron apices, and counter-rotating streamwise vortices of axial and radial vorticity develop from the chevron notches. The decay of streamwise vortices is accompanied by the formation of C-shaped structures. The three-dimensional analysis allows quantifying the vortex stretching and tilting activity, which, for the circular jet exit, is related to the azimuthal instabilities and the streamwise vortices connecting the vortex rings. In the chevron jet, stretching and tilting peak during the formation of C-structures. Following Powell’s aeroacoustic analogy, the spatial distribution of the source term is mapped, evaluating the temporal derivative of the Lamb vector. The spatio-temporal evolution of such source term is visualized revealing that the events of highest activity are associated with the processes of vortex-ring pairing and vortex-ring disruption for the circular jet, and with the decay of streamwise instabilities and the formation of C-shaped structures for the chevron case.","acoustic noise; aeroacoustics; flow instability; flow visualisation; jets; spatiotemporal phenomena; turbulence; vortices","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:bb32b304-63ec-4766-9b44-eeeb97cbdb28","http://resolver.tudelft.nl/uuid:bb32b304-63ec-4766-9b44-eeeb97cbdb28","Power output of offshore wind farms in relation to atmospheric stability","Alblas, L.; Bierbooms, W.A.A.M.; Veldkamp, D.","","2014","Atmospheric stability is known to influence wind farm power output, by affecting power losses due to wakes. This research tries to answer what atmospheric stability does to the power production and how conventional simulations using the Jensen wake model compare and can be improved. Data is used from two offshore wind farms, Egmond aan Zee (OWEZ) and North Hoyle. Stability distributions are determined using metmast data. By combining this data with the production data, the influence of stability on the power output is studied. It is found that very unstable conditions result in higher power output (i.e. smaller wake losses) than near-neutral conditions, and these again show higher power output than during very stable conditions. Differences in normalized power output of 10-20% exist between the very unstable and very stable conditions. Simulations can be improved by adapting the wake decay constant (WDC).","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:4cb98048-9b1f-4565-a8d1-1b4aae221ac6","http://resolver.tudelft.nl/uuid:4cb98048-9b1f-4565-a8d1-1b4aae221ac6","Wind turbine design in Barcelona; sun, sea, MATLAB and load calculations; enjoying the good life","Nouwens, A.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2d0119bf-a254-4879-adae-7242baeb20ff","http://resolver.tudelft.nl/uuid:2d0119bf-a254-4879-adae-7242baeb20ff","Far-zone contributions to the gravity field quantities by means of Molodensky’s truncation coefficients","Tenzer, R.; Novak, P.; Prutkin, I.; Ellmann, A.; Vajda, P.","","2009","To reduce the numerical complexity of inverse solutions to large systems of discretised integral equations in gravimetric geoid/quasigeoid modelling, the surface domain of Green’s integrals is subdivided into the near-zone and far-zone integration sub-domains. The inversion is performed for the near zone using regional detailed gravity data. The farzone contributions to the gravity field quantities are estimated from an available global geopotential model using techniques for a spherical harmonic analysis of the gravity field. For computing the far-zone contributions by means of Green’s integrals, truncation coefficients are applied. Different forms of truncation coefficients have been derived depending on a type of integrals in solving various geodetic boundary-value problems. In this study, we utilise Molodensky’s truncation coefficients to Green’s integrals for computing the far-zone contributions to the disturbing potential, the gravity disturbance, and the gravity anomaly. We also demonstrate that Molodensky’s truncation coefficients can be uniformly applied to all types of Green’s integrals used in solving the boundaryvalue problems. The numerical example of the far-zone contributions to the gravity field quantities is given over the area of study which comprises the Canadian Rocky Mountains. The coefficients of a global geopotential model and a detailed digital terrain model are used as input data.","far-zone contribution; geoid; gravity; Greens integrals; truncation coefficients","en","journal article","Springer","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:e02db37b-5e7c-4139-8576-cd210f3c8dc3","http://resolver.tudelft.nl/uuid:e02db37b-5e7c-4139-8576-cd210f3c8dc3","An optimal control framework for estimating autopilot safety margins","Govindarjan, N.; De Visser, C.C.; Van Kampen, E.; Krishnakumar, K.; Barlow, J.; Stepanyan, V.","","2014","This paper presents an optimal control framework to determine a collection of open-loop command signals that mathematically guarantees operation of an aircraft within certain prescribed state constraints. The framework is specifically applied to estimate margins for the reference command inputs of aircraft autopilot systems, so that safe operation within a given flight envelope can be assured under appropriate control action. Flight envelope excursions are generally considered as precursors to Loss-Of-Control incidents, and hence, these margins contain safety critical information that can help improve the situational awareness on-board the aircraft. In off-nominal conditions, the computed safety margins provide indications of a degraded aircraft with reduced flying and handling qualities. These indications appear in the form of increasingly more strict limits on the autopilot reference command input. The entire framework is illustrated on an example problem involving a pitch dynamics model with state constraints on the pitch attitude. Simulations are conducted wherein margins are computed for the reference pitch command of the pitch hold system, while the aircraft enters an off-nominal condition with severely degraded system dynamics and reduced elevator effectiveness.","optimal control; multivariate splines; aircraft safety; loss of control","en","journal article","AIAA","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:3370a4c4-78c5-481d-9367-e6969a46ad70","http://resolver.tudelft.nl/uuid:3370a4c4-78c5-481d-9367-e6969a46ad70","Engineering excellence at Rolls-Royce; a taste of English culture","Schnelders, J.","","2013","Rolls-Royce is one of the most well-known brands in the world and synonymous with the highest engineering quality. Amongst Aerospace Engineers, Rolls-Royce is directly associated with the Trent turbofan aircraft engines. The engines power the world’s newest passenger aircraft, including the Boeing 787 Dreamliner and the large Airbus A380. A Rolls-Royce powered aircraft takes o! or lands every 2.5 seconds.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:cd3ef1db-955d-4c77-8088-7dbf78a8643a","http://resolver.tudelft.nl/uuid:cd3ef1db-955d-4c77-8088-7dbf78a8643a","Multiplatform Instantaneous GNSS Ambiguity Resolution for Triple- and Quadruple-Antenna Configurations with Constraints","Buist, P.J.; Teunissen, P.J.G.; Giorgi, G.; Verhagen, S.","","2009","Traditionally the relative positioning and attitude determination problem are treated as independent. In this contribution we will investigate the possibilities of using multiantenna (i.e., triple and quadruple) data, not only for attitude determination but also for relative positioning. The methods developed are rigorous and have the additional advantage that they improve ambiguity resolution on the unconstrained baseline(s) and the overall success rate of ambiguity resolution between a number of antennas.","","en","journal article","Hindawi Publishing Corporation","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:f852545f-2946-4556-9ef8-0b5cdbdaf289","http://resolver.tudelft.nl/uuid:f852545f-2946-4556-9ef8-0b5cdbdaf289","The Economic Potential of Kite Power","Grete, C.","","2014","The fundamental working principle of kite power generation is straightforward: a fast-flying kite pulls a tether from a drum, which drives a generator. At the maximum reel-out length, the kite is de-powered and pulled back, to initiate a new pumping cycle. The objective of this innovative technology is to make electricity generation affordable, reliable and clean. The frequently asked question is “How much does it cost?”","Airborne Wind Energy; LCOE","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","Wind Energy","","","",""
"uuid:321de1c9-bd2d-471c-91fd-7a27511665fa","http://resolver.tudelft.nl/uuid:321de1c9-bd2d-471c-91fd-7a27511665fa","Fly Aeolus; a new step in business travelling","Fassaert, N.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7416fb8b-7e77-4001-bd5d-ad31174b1ae1","http://resolver.tudelft.nl/uuid:7416fb8b-7e77-4001-bd5d-ad31174b1ae1","Seal-healing coatings; a smart approach for life extension of aircraft strcutures","Garcia, S.J.","","2011","","seal-healing coatings","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:84393643-c7a0-481e-bd8f-b2df4b645d28","http://resolver.tudelft.nl/uuid:84393643-c7a0-481e-bd8f-b2df4b645d28","T-Minus engineering: A company in rocketry","Olthof, H.; Uitendaal, M.","","2013","The idea started when a group of students from Delft Aerospace Rocket Engineering were sitting at the breakfast table of the Esrange launch base canteen, in the far north of Sweden. It was the day after the successful launch of the self-built Stratos rocket, that broke the European altitude record for amateur rockets. “This is what we love to do, and apparently we are good at it. Let’s try and make a living building rockets”.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:860aa064-b343-4d60-ab52-81730d286edb","http://resolver.tudelft.nl/uuid:860aa064-b343-4d60-ab52-81730d286edb","Gliding Swifts Attain Laminar Flow over Rough Wings","Lentink, D.; De Kat, R.","","2014","Swifts are among the most aerodynamically refined gliding birds. However, the overlapping vanes and protruding shafts of their primary feathers make swift wings remarkably rough for their size. Wing roughness height is 1–2% of chord length on the upper surface—10,000 times rougher than sailplane wings. Sailplanes depend on extreme wing smoothness to increase the area of laminar flow on the wing surface and minimize drag for extended glides. To understand why the swift does not rely on smooth wings, we used a stethoscope to map laminar flow over preserved wings in a low-turbulence wind tunnel. By combining laminar area, lift, and drag measurements, we show that average area of laminar flow on swift wings is 69% (n = 3; std 13%) of their total area during glides that maximize flight distance and duration—similar to high-performance sailplanes. Our aerodynamic analysis indicates that swifts attain laminar flow over their rough wings because their wing size is comparable to the distance the air travels (after a roughness-induced perturbation) before it transitions from laminar to turbulent. To interpret the function of swift wing roughness, we simulated its effect on smooth model wings using physical models. This manipulation shows that laminar flow is reduced and drag increased at high speeds. At the speeds at which swifts cruise, however, swift-like roughness prolongs laminar flow and reduces drag. This feature gives small birds with rudimentary wings an edge during the evolution of glide performance.","","en","journal article","Public Library of Science","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e9834dba-055a-4d4c-9c87-d3e646c28b62","http://resolver.tudelft.nl/uuid:e9834dba-055a-4d4c-9c87-d3e646c28b62","The ahead project: Advanced hybrid engines for aircraft development","Rao, A.G.; Yin, F.","","2013","Aviation is an ever-increasing market and more passengers and cargo are carried each year. The world is becoming ever more connected. However, this does come at a price: aviation has a marked in!uence on the environment. If aviation is to thrive in the future, breakthroughs in aircraft design and propulsion systems are needed. The AHEAD project is an attempt at achieving such a breakthrough.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:17cf65d1-c0ff-410c-9362-0b6dd0a4834e","http://resolver.tudelft.nl/uuid:17cf65d1-c0ff-410c-9362-0b6dd0a4834e","Design for air-to-air refuelling operations; new passenger and tanker aircraft design for AAR scenarios","Li, M.O.","","2014","Air-to-air refuelling is a way to improve fuel efficiency of the overall transport system without waiting for the improvement of basic aviation technology. To take full advantage of such an operation, both passenger aircraft and tanker aircraft (which deliver required fuel to the passenger aircraft in halfway) must be designed accordingly. Moreover, the issues of safety and reliability must also be considered besides fuel economy.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8dfdb721-9d3b-4100-97f9-7aa7864015dc","http://resolver.tudelft.nl/uuid:8dfdb721-9d3b-4100-97f9-7aa7864015dc","The story behind the Lambach aircraft; keeping a piece of Dutch aviation history alive","Kooij, G.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:77c34b21-3de7-42f8-a979-3fad86c37ea6","http://resolver.tudelft.nl/uuid:77c34b21-3de7-42f8-a979-3fad86c37ea6","Spectropolarimetric signatures of Earth-like extrasolar planets","Stam, D.M.","","2007","We present results of numerical simulations of flux F and degree of polarization P of light that is reflected by Earth–like extrasolar planets orbiting solar type stars. Our results are presented as functions of the wavelength (from 0.3 to 1.0 ?m, with 0.001 ?m spectral resolution) and as functions of the planetary phase angle. We use different surface coverages for our model planets, including vegetation and a Fresnel reflecting ocean, and clear and cloudy atmospheres. Our adding-doubling radiative transfer algorithm, which fully includes multiple scattering and polarization, only handles horizontally homogeneous planets, so we simulate fluxes and polarization of horizontally inhomogeneous planets by weighting results obtained for homogeneous planets. Like F, P of the reflected starlight is shown to depend strongly on the phase angle, on the composition and structure of the planetary atmosphere, on the reflective properties of the underlying surface, and on the wavelength, in particular in wavelength regions with gaseous absorption bands. The sensitivity of P to a planet’s physical properties appears to be different than that of F. Combining flux with polarization observations thus makes for a strong tool for characterizing extrasolar planets. The calculated total and polarized fluxes are made available through the CDS.","polarization techniques; polarimetric stars; planetary systems radiative transfer Earth","en","journal article","EDP sciences","","","","","","","","Aerospace Engineering","Aerospace Engineering Department","","","",""
"uuid:7ef4ef66-aeda-4b44-90f8-a33ec0e714e7","http://resolver.tudelft.nl/uuid:7ef4ef66-aeda-4b44-90f8-a33ec0e714e7","Experimental and numerical analysis of a beam made of adhesively bonded tailor-made blanks","Monaco, A.; Sinke, J.; Benedictus, R.","","2008","For aircraft structures, it is clear that the design and the selection of materials play an important role in the performance of the aircraft. The production costs are also important. The concept of tailor-made blanks (TMBs) is based on the use of dedicated blanks, made of different alloys and/or thickness in order to satisfy different demands such as an increase, if necessary, of local strength, stiffness, and damage tolerance. This paper describes the results of a study to assess the potential weight and cost savings of using TMBs in a typical aerospace structure. A bonded structure representing the floor beam of an aircraft has been selected, analyzed, and tested to validate the numerical and analytical predictions made with MATLAB and finite-element method. The results show weight reduction of 12% and 37% for two studied configurations, compared to the reference beam.","Tailor-made blanks; Adhesive bonding; FEM modeling; Safety factor; Failure","en","journal article","Springer","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures and Materials","","","",""
"uuid:81a2cd10-08fb-4bb2-b8ba-2d04944b901c","http://resolver.tudelft.nl/uuid:81a2cd10-08fb-4bb2-b8ba-2d04944b901c","The arms of the international space station; operating the robotic arms of the ISS","Cormier, D.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a7be07c6-81b2-4486-a993-72a2da24644f","http://resolver.tudelft.nl/uuid:a7be07c6-81b2-4486-a993-72a2da24644f","A high-rate shape memory alloy actuator for aerodynamic load control on wind turbines","Lara-Quintanilla, A.; Hulskamp, A.W.; Bersee, H.E.N.","","2013","This paper discusses the development of a high rate shape memory alloy (SMA) driven actuator. The concept of the actuator was developed to act as aerodynamic load control surface on wind turbines. It was designed as a plate or beam-like structure with prestrained SMA wires embedded off its neutral axis. Moreover, the SMA material was embedded in channels through which air was forced to actively cool the wires when the recovery load was to be released. Wires were implemented on both sides of the neutral axis to deflect the beam in both directions. Thermal analysis of the cooling channels showed that they increased the cooling up to tenfold in comparison to the same set-up without forced convection. Subsequently a fuzzy logic controller was designed to control the thermo-mechanical system. The inputs were the error between the deflection and the set point, the value of the set point and the time derivative of the set point. The output consisted of two signals to the valves that controlled the flow through the channels and a signal heating signal that was split to both sets of wires, depending on its sign. The controller was tested on an antagonistic set-up, through which a similar thermo-mechanic behaviour as with the actuator was obtained, but eliminating the beam dynamics. The results were satisfactory; an actuation bandwidth of 1Hz was attained. Subsequently, the controller was tested on the actuator. With increasing actuation frequency, until 0.6Hz a relatively small error between the set point and the actual deflection was observed. Above that frequency the error increased, but also the sinusoidal response was lost. This is believed to be due to snap-through behaviour around the neutral position of the actuator. This was substantiated by the apparent inability of the actuator to track the set point around the neutral position in tracking a composite sinusoidal set point.","Shape Memory Alloys; Fuzzy Logic Controller; Aerodynamic Load Control; Wind Turbines; Control","en","journal article","Sage Publications","","","","","","","","Aerospace Engineering","Structure Integrity and Composites","","","",""
"uuid:7da1420a-3d42-4c15-9131-7a69a73e0e42","http://resolver.tudelft.nl/uuid:7da1420a-3d42-4c15-9131-7a69a73e0e42","Conditionality of inverse solutions to discretised integral equations in geoid modelling from local gravity data","Tenzer, R.; Novák, P.","","2008","The eigenvalue decomposition technique is used for analysis of conditionality of two alternative solutions for a determination of the geoid from local gravity data. The first solution is based on the standard two-step approach utilising the inverse of the Abel-Poisson integral equation (downward continuation) and consequently the Stokes/Hotine integration (gravity inversion). The second solution is based on a single integral that combines the downward continuation and the gravity inversion in one integral equation. Extreme eigenvalues and corresponding condition numbers of matrix operators are investigated to compare the stability of inverse problems of the above-mentioned computational models. To preserve a dominantly diagonal structure of the matrices for inverse solutions, the horizontal positions of the parameterised solution on the geoid and of data points are identical. The numerical experiments using real data reveal that the direct gravity inversion is numerically more stable than the downward continuation procedure in the two-step approach.","geoid; gravity; inverse problem; numerical stability","en","journal article","Springer","","","","","","","","Aerospace Engineering","Physical and Space Geodesy","","","",""
"uuid:b923961f-065f-4433-8a8b-5ceb6df74fe8","http://resolver.tudelft.nl/uuid:b923961f-065f-4433-8a8b-5ceb6df74fe8","Project BEAR; filming at the edge of space","Hiddink, S.; Baan, M.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:23dd804b-1432-4060-b938-0cc301a90493","http://resolver.tudelft.nl/uuid:23dd804b-1432-4060-b938-0cc301a90493","Numerical assessment of failure mechanisms in fibre metal laminates","Hashagen, F.; De Borst, R.","","1998","In this contribution numerical models are discussed for describing failure mechanisms in fibre metal laminates. Fibre metal laminates form a new class of materials which are considered for a possible application to the fuselage of future aircraft generations. The intensive experimental analyses of these materials are focused on the assessment of their residual strength and on the assessment of new design methods. To support the experimental analyses numerical models are used to describe cracking and delamination in fibre metal laminates. A special continuum element and a corresponding interface element are introduced. Furthermore, loading functions are applied which account for cracking and delamination. Subsequently, results are discussed which are obtained from numerical analyses of the residual strength of plates made of GLARETM . Finally, the splicing technique as a new design method is assessed by a comparison between numerical and experimental results.","fibre metal laminates; solid-like shell; interface elements; crack growth; residual strength; delamination; splices","en","journal article","Delft University of Technology","","","","","","","","Aerospace Engineering","Koiter Institute Delft","","","",""
"uuid:824fef92-4040-4138-bfc1-3fe8486b36a1","http://resolver.tudelft.nl/uuid:824fef92-4040-4138-bfc1-3fe8486b36a1","Harmonic analysis of total electron contents time series: Methodology and results","Amiri-Simkooei, A.R.; Asgari, J.","","2011","In an attempt to model regular variations of the ionosphere, the least-squares harmonic estimation is applied to the time series of the total electron contents (TEC) provided by the JPL analysis center. Multivariate and modulated harmonic estimation spectra are introduced and estimated for the series to detect the regular and modulated dominant frequencies of the periodic patterns. Two significant periodic patterns are the diurnal and annual signals with periods of 24/n hours and 365.25/n days (n = 1, 2,
), which are the Fourier series decomposition of the regular daily and yearly periodic variations of the ionosphere. The spectrum shows a cluster of periods near 27 days, thereby indicating irregularities at this solar cycle period. A series of peaks, with periods close to the diurnal signal and its harmonics, are evident in the spectrum. In fact, the daily signal harmonics of xi = 2pi are modulated with the annual signal harmonics of xj = 2pj/365.25 as xijM = 2pi(1 ± j/365.25i). Among them, at low and midlatitudes, the largest variations belong to the diurnal signal modulated to the semiannual signal. Some preliminary results on the modulated part are presented. The maximum ranges of the modulated daily signal are ±15 TECU and ±6 TECU at high and low solar periods, respectively. A model consisting of purely harmonic functions plusmodulated ones is capable of studying known regular anomalies of the ionosphere, which is currently in progress","ionospheric modeling; harmonic estimation; total electron content (TEC); modulated signal","en","journal article","Springer","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:626629b7-81f4-4929-ae8d-c4290f2a218f","http://resolver.tudelft.nl/uuid:626629b7-81f4-4929-ae8d-c4290f2a218f","Beyond the horizon; flying next generation solar aircraft even further","Janssen, Y.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9eabdd0c-098b-4a66-a9ce-ed5230e57c5f","http://resolver.tudelft.nl/uuid:9eabdd0c-098b-4a66-a9ce-ed5230e57c5f","On the non-uniqueness of local quasi-geoids computed from terrestrial gravity anomalies","Prutkin, I.; Klees, R.","","2007","We consider the problem of local (quasi-)geoid modelling from terrestrial gravity anomalies. Whereas this problem is uniquely solvable (up to spherical harmonic degree one) if gravity anomalies are globally available, the problem is non-unique if gravity anomalies are only available within a local area, which is the typical situation in local/regional gravity field modelling. We derive a mathematical description of the kernel of the gravity anomaly operator. The non-uniqueness can be removed using external height anomaly information, e.g., provided by GPS-levelling. The corresponding problem is formulated as a Cauchy problem for the Laplace equation. The existence and uniqueness of the solution of the Cauchy problem is guaranteed by the Cauchy–Kowalevskaya theorem. We propose several numerical procedures to compute the solution of the Cauchy problem from given differences between gravimetric and geometric height anomalies. We apply the numerical techniques to real data over the Netherlands and Germany. We show that we can compute a unique quasi-geoid from observed gravimetric and geometric height anomalies, which agree with the data within the expected noise level. We conclude that observed differences between gravimetric height anomalies and geometric height anomalies derived from GPS and levelling cannot only be attributed to systematic errors in the data sets, but are also caused by the intrinsic non-uniqueness of the problem of local quasi-geoid modelling from gravity anomalies. Hence, GPS-levelling data are necessary to get a unique solution, which also implies that they should not be used to validate local quasi-geoid solutions computed on the basis of gravity anomalies.","Local gravity field modelling; Non-uniqueness; Cauchy problem for the Laplace equation; GPS-levelling data; Quasi-geoid","en","journal article","Springer","","","","","","","","Aerospace Engineering","Delft Institute of earth Observation and Space Systems","","","",""
"uuid:48113410-4855-49c8-ae42-04c577cf53e9","http://resolver.tudelft.nl/uuid:48113410-4855-49c8-ae42-04c577cf53e9","Harvesting wave energy; developing a wave energy converter","Fokker, D.; Caro, R.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:404e275c-7322-4014-8faa-891b3588ff4d","http://resolver.tudelft.nl/uuid:404e275c-7322-4014-8faa-891b3588ff4d","TU students sweep UAV design competition","Klein, R.; Brust, S.; Brown, M.; Vos, R.","","2013","To design a high-altitude long-endurance UAV to fly a twenty-hour reconnaissance mission at an altitude of 80,000ft, was the assignment for this year’s undergraduate design competition. The competition was organized by the American Institute of Aeronautics and Astronautics (AIAA). Three students from Delft demonstrated superior design skills, winning the first, second, and third prizes.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ed685108-6eba-46e1-ac0d-07a13c25a2f0","http://resolver.tudelft.nl/uuid:ed685108-6eba-46e1-ac0d-07a13c25a2f0","Higher?order ionospheric effects on the GPS reference frame and velocities","Petrie, E.J.; King, M.A.; Moore, P.; Lavallée, D.A.","","2010","We describe how GPS time series are influenced by higher?order ionospheric effects over the last solar cycle (1995–2008) and examine implications for geophysical studies. Using 14 years of globally reprocessed solutions, we demonstrate the effect on the reference frame. Including second? and third?order ionospheric terms causes up to 10 mm difference in the smoothed transformation to the International Terrestrial Reference Frame (ITRF) 2005, with the Z translation term dominant. Scale is also slightly affected, with a change of up to ?0.05 ppb. After transformation to ITRF2005, residual effects on vertical site velocities are as high as 0.34 mm yr?1. We assess the effect of the magnetic field model on the second?order term and find a time?varying difference of 0–2 mm in the Z translation. We also assess the effect of omitting the third?order term. We find that while the second?order term is responsible for almost all the Z translation effects, it is the combination of the second? and third?order terms that causes the effect on scale. Comparison of our GPS reprocessing with ITRF2005 suggests that GPS origin rates may vary with time period. For example, we find Z translation rates of ?0.82 ± 0.17 mm yr?1 for 1995–2008 and 0.17 ± 0.24 mm yr?1 for 1995–2005. If GPS were to contribute to origin rate definition for future ITRFs, higher?order ionospheric corrections would need to be applied due to their effect on translation parameters during solar maximum.","higher?order ionospheric; reference frame; vertical rates","en","journal article","American Geophysical Union","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:99fb9dcf-e90e-4fa9-8deb-92c6d4e55593","http://resolver.tudelft.nl/uuid:99fb9dcf-e90e-4fa9-8deb-92c6d4e55593","Ultra-high degree spherical harmonic analysis and synthesis using extended-range arithmetic","Wittwer, T.; Klees, R.; Seitz, K.; Heck, B.","","2007","We present software for spherical harmonic analysis (SHA) and spherical harmonic synthesis (SHS), which can be used for essentially arbitrary degrees and all co-latitudes in the interval (0°, 180°). The routines use extended-range floating-point arithmetic, in particular for the computation of the associated Legendre functions. The price to be paid is an increased computation time; for degree 3,000, the extended-range arithmetic SHS program takes 49 times longer than its standard arithmetic counterpart. The extended-range SHS and SHA routines allow us to test existing routines for SHA and SHS. A comparison with the publicly available SHS routine GEOGFG18 by Wenzel and HARMONIC SYNTH by Holmes and Pavlis confirms what is known about the stability of these programs. GEOGFG18 gives errors <1 mm for latitudes [-89°57.5?, 89°57.5?] and maximum degree 1,800. Higher degrees significantly limit the range of acceptable latitudes for a given accuracy. HARMONIC SYNTH gives good results up to degree 2,700 for almost the whole latitude range. The errors increase towards the North pole and exceed 1 mm at latitude 82° for degree 2,700. For a maximum degree 3,000, HARMONIC SYNTH produces errors exceeding 1 mm at latitudes of about 60°, whereas GEOGFG18 is limited to latitudes below 45°. Further extending the latitudinal band towards the poles may produce errors of several metres for both programs. A SHA of a uniform random signal on the sphere shows significant errors beyond degree 1,700 for the SHA program SHA by Heck and Seitz.","Spherical harmonic analysis; Spherical harmonic synthesis; Extended-range arithmetic; Numerical stability","en","journal article","Springer","","","","","","","","Aerospace Engineering","Delft Institute of Earth Observation and Space Systems","","","",""
"uuid:a2bd15ed-3a3e-4aa5-98a7-cdc4951d900f","http://resolver.tudelft.nl/uuid:a2bd15ed-3a3e-4aa5-98a7-cdc4951d900f","A TVD uncertainty quantification method with bounded error applied to transonic airfoil flutter","Witteveen, J.A.S.; Bijl, H.","","2009","The Unsteady Adaptive Stochastic Finite Elements (UASFE) approach is a robust and efficient uncertainty quantification method for resolving the effect of random parameters in unsteady simulations. In this paper, it is shown that the underlying Adaptive Stochastic Finite Elements (ASFE) method for steady problems based on Newton-Cotes quadrature in simplex elements is extrema diminishing (ED). It is also shown that themethod is total variation diminishing (TVD) for one randomparameter and for multiple random parameters for first degree Newton-Cotes quadrature. It is proven that the interpolation of oscillatory samples at constant phase in the UASFE method for unsteady problems results in a bounded error as function of the phase for periodic responses and under certain conditions also in a bounded error in time. The twomethods are applied to a steady transonic airfoil flow and a transonic airfoil flutter problem.","total variation diminishing; extrema diminishing; error bounds; stochastic finite elements; uncertainty quantification; transonic flow; transonic flutter","en","journal article","Global-Science Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d6eecd09-2c23-477f-a404-7c1fe6fd5100","http://resolver.tudelft.nl/uuid:d6eecd09-2c23-477f-a404-7c1fe6fd5100","Effect of fiber-matrix adhesion on the creep behavior of CF/PPS composites: Temperature and physical aging characterization","Motta Dias, M.H.; Jansen, K.M.B.; Luinge, J.W.; Bersee, H.E.N.; Benedictus, R.","","2016","The influence of fiber-matrix adhesion on the linear viscoelastic creep behavior of ‘as received’ and ‘surface modified’ carbon fibers (AR-CF and SM-CF, respectively) reinforced polyphenylene sulfide (PPS) composite materials was investigated. Short-term tensile creep tests were performed on ±45° specimens under six different isothermal conditions, 40, 50, 60, 65, 70 and 75 °C. Physical aging effects were evaluated on both systems using the short-term test method established by Struik. The results showed that the shapes of the curves were affected neither by physical aging nor by the test temperature, allowing then superposition to be made. A unified model was proposed with a single physical aging and temperature-dependent shift factor, aT,te. It was suggested that the surface treatment carried out in SM-CF/PPS had two major effects on the creep response of CF/PPS composites at a reference temperature of 40 °C: a lowering of the initial compliance of about 25 % and a slowing down of the creep response of about 1.1 decade.","viscoelastic creep behavior; physical aging; CF/PPS composites; time aging; time superposition; time temperature superposition principle (TTSP)","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:1e416ce8-db9f-4711-babf-7171f9e258cd","http://resolver.tudelft.nl/uuid:1e416ce8-db9f-4711-babf-7171f9e258cd","DEOS mass transport model (DMT-1) based on GRACE satellite data: Methodology and validation","Liu, X.L.; Ditmar, P.G.; Siemes, C.; Slobbe, D.C.; Revtova, E.; Klees, R.; Riva, R.; Zhao, Q.","","2010","","","en","journal article","Royal Astronomical Society","","","","","","","","Aerospace Engineering","DEOS","","","",""
"uuid:cca870f3-5c66-4c5a-9e2f-3be89154babf","http://resolver.tudelft.nl/uuid:cca870f3-5c66-4c5a-9e2f-3be89154babf","A benchmark for fault tolerant flight control evaluation","Smaili, H.; Breeman, J.; Lombaerts, T.; Stroosma, O.","","2013","A large transport aircraft simulation benchmark (REconfigurable COntrol for Vehicle Emergency Return ? RECOVER) has been developed within the GARTEUR (Group for Aeronautical Research and Technology in Europe) Flight Mechanics Action Group 16 (FM-AG(16)) on Fault Tolerant Control (2004 2008) for the integrated evaluation of fault detection and identification (FDI) and reconfigurable flight control strategies. The benchmark includes a suitable set of assessment criteria and failure cases, based on reconstructed accident scenarios, to assess the potential of new adaptive control strategies to improve aircraft survivability. The application of reconstruction and modeling techniques, based on accident flight data, has resulted in high-fidelity nonlinear aircraft and fault models to evaluate new Fault Tolerant Flight Control (FTFC) concepts and their real-time performance to accommodate in-flight failures.","","en","journal article","EDP sciences","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:3028692b-3403-4fe9-84c3-063575ff5257","http://resolver.tudelft.nl/uuid:3028692b-3403-4fe9-84c3-063575ff5257","The Montgolfier brothers; history of the hot air balloon","Schneiders, J.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:791fce8a-e31b-448b-ab1d-495c018d9561","http://resolver.tudelft.nl/uuid:791fce8a-e31b-448b-ab1d-495c018d9561","A steady solution for Prandtl’s self-similar vortex sheet spirals","Van Kuik, G.A.M.","","2008","Prandtl's [L. Prandtl, Über die Entstehung von Wirbeln in der idealen Flüssigkeit, mit Anwendung auf die Tragflügeltheorie und andere Aufgaben, in: von Kármán, Levi-Cevita (Eds.), Vorträge aus dem Gebiete der Hydro- und Aerodynamik, Springer, Berlin, 1922] self-similar, semi-infinite, free vortex sheets are characterized by a two-dimensional unsteady flow around an invariable exponential spiral. A similar but steady spiral flow has been published by Schmidt and Sparenberg [G.H. Schmidt, J.A. Sparenberg, On the edge singularity of an actuator disk with large constant normal load, J. Ship Research 21 (1977) 125]. This flow is shown to be, kinematically, the steady solution in Prandtl's class of spirals but with a different dynamic boundary condition since it is not a free vortex sheet but carries a constant load. Due to the kinematic similarity, the analysis of Prandtl's spirals by van Kuik [G.A.M. van Kuik, The flow induced by Prandtl's self-similar vortex sheet spirals at infinite distances from the spiral kernel, Eur. J. Mech. B/Fluids 23 (4) (2004) 607–616] is also valid for the spiral with steady flow. As for Prandtl's spirals, the steady spiral flow requires a description on a multi-branched Riemann surface, by which an interpretation in the single-branched two-dimensional surface is impossible.","Spiral; Vortex sheets; Prandtl","en","journal article","Elsevier","","","","","","","","Aerospace Engineering","Aerospace Design, Integration and Operations","","","",""
"uuid:60b43ab6-99cc-40e3-9d3c-e35a3061f5a9","http://resolver.tudelft.nl/uuid:60b43ab6-99cc-40e3-9d3c-e35a3061f5a9","Sequential combination of troposphere time series","Keshin, M.","","2007","","","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:34f6fe0c-6955-42e4-9907-c5bb32093d8d","http://resolver.tudelft.nl/uuid:34f6fe0c-6955-42e4-9907-c5bb32093d8d","A boy's dream the size of a milk carton","Visscher, R.","Verhoeven, C. (contributor)","2007","Student satellites are the latest hype in education. By allowing students to build their own satellites, they learn to solve problems faster and build more innovatively. In Delft, students are now putting the final touches on the Delft-C3, a nanosatellite the size of a milk carton. For every student, and for the instructors as well, this a boys dream.","Delfi-C3; satellites","en","journal article","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b04fae78-0598-4e3c-abd4-a4d4e8a1bfd4","http://resolver.tudelft.nl/uuid:b04fae78-0598-4e3c-abd4-a4d4e8a1bfd4","Aerodynamic Experiments on DelFly II: Unsteady Lift Enhancement","De Clercq, K.M.E.; De Kat, R.; Remes, B.; Van Oudheusden, B.W.; Bijl, H.","","2009","Particle image velocimetry measurements and simultaneous force measurements have been performed on the DelFly II flapping-wing MAV, to investigate the flow-field behavior and the aerodynamic forces generated. For flapping wing motion it is expected that both the clap and peel mechanism and the occurrence of a leading edge vortex during the translational phase play an important role in unsteady lift generation. Furthermore, the flexibility of the wing foil is also considered of primary relevance. The PIV analysis shows a strong influx between the wings during the peel but no downward expelling jet during the clap. The force measurements reveal that the peel, oppositely to the clap, contributes significantly to the lift. The PIV visualization suggests the occurrence of a leading edge vortex during the first half of the in- and outstroke, which is supported by a simultaneous augmentation in lift. The early generation of a leading edge vortex during the flex cannot be assessed from the PIV images due to optical obstruction, but is likely to appear since the wing flexing is accompanied with a large increase in lift.","","en","journal article","Multi-Science Publishing","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:4cb2d200-e5e9-4011-9e43-4ae264c6db8d","http://resolver.tudelft.nl/uuid:4cb2d200-e5e9-4011-9e43-4ae264c6db8d","Dancing building prevents collapse","Visscher, R.","Beukers, A. (contributor)","2007","In future, anybody caught inside a building during an earthquake need no longer fear the roof collapsing on them. Thanks to the use of composite materials, all the building will do is dance along, riding the waves of the earthquake. At least, according to Professor Ir. Adriaan Beukers of the Aerospace Engineering department of Delft University of Technology or TU Delft. He is developing composite columns that will enable a building to be put up in a matter of seconds.","earthquake; composite columns","en","journal article","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b3cbae91-30e0-495c-ace4-2b0a5c995d0f","http://resolver.tudelft.nl/uuid:b3cbae91-30e0-495c-ace4-2b0a5c995d0f","A Novel Emergent State Control Law for an Integrated Helicopter/Turboshaft Engine System","Zhang, H.; Li, Y.; Deng, S.","","2014","A two-layer robust control scheme is proposed to get a better response ability for emergency maneuvers of helicopter. Note that the power used in ascending flight is the main coupling between helicopter and its turboshaft engines; therefore vertical flight control is separated from conventional helicopter control loops and combined with fuel flow and turbine bleeding to new control loops denoted as an inner layer, whereas the mission level flight control is as the out layer. A conclusion in global asymptotically tracking for devising this new scheme is firstly derived from a Generalized Gronwall-Bellman approach. Due to this integrated designing, not only is the helicopter better controlled, but also much better power rapid tracking is realized for engines. Simulations are conducted to validate the new scheme in emergent ascending and descending flights, and the results illustrate that the response time of the closed-loop system is dramatically reduced when compared to the traditional one. Moreover, the presented system also has better dynamic performance under inferences.","","en","journal article","Hindawi Publishing Corporation","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:f2de0964-7bf9-4232-aae0-3b3fff3f953e","http://resolver.tudelft.nl/uuid:f2de0964-7bf9-4232-aae0-3b3fff3f953e","Rigid-body kinematics versus flapping kinematics of a flapping wing micro air vehicle","Caetano, J.V.; Weehuizen, M.B.; De Visser, C.C.; De Croon, G.C.H.E.; Mulder, M.","","2015","Several formulations have been proposed to model the dynamics of ornithopters, with inconclusive results regarding the need for complex kinematic formulations. Furthermore, the impact of assumptions made in the collected results was never assessed by comparing simulations with real flight data. In this study two dynamic models of a Flapping Wing Micro Aerial Vehicle (FWMAV) were derived and compared: a) single rigid body aircraft equations of motion and b) Virtual Work Principle derivation for multiple rigid body flapping kinematics. The aerodynamic forces and moments were compared by feeding the states that were reconstructed from the position and attitude data of a 17 gram free flying FWMAV into the dynamic equations of both formulations. To understand the applicability of rigid body formulations to FWMAVs, six wing-to-body mass ratios and two wing configurations were studied using real flight data. The results show that rigid body models are valid for the aerodynamic reconstruction of FWMAVs with four wings in ‘X’ configuration and two-winged FWMAV with a total wing-to-body mass ratio below 24% and 5.6%, respectively, without considerable information loss.","","en","journal article","AIAA","","","","","","","","Aerospace Engineering","","","","",""
"uuid:787ab8c6-80bb-446a-9c86-7040f662b731","http://resolver.tudelft.nl/uuid:787ab8c6-80bb-446a-9c86-7040f662b731","Multidisciplinary integrated field campaign to an acidic Martian Earth analogue with astrobiological interest: Rio Tinto","Gómez, F.; Walter, N.; Amils, R.; Rull, F.; Klingelhöfer, A.K.; Kviderova, J.; Sarrazin, P.; Foing, B.; Behar, A.; Fleischer, I.; Parro, V.; Garcia-Villadangos, M.; Balke, D.; Martin Ramos, J.D.; Direito, S.; Mahapatra, P.","","2011","Recently reported results from latest Mars Orbiters and Rovers missions are transforming our opinion about the red planet. That dry and inhospitable planet reported in the past is becoming a wetter planet with high probabilities of water existence in the past. Nowadays, some results seem to indicate the presence of water beneath the Mars surface. But also mineralogy studies by NASA Opportunity Rover report iron oxides and hydroxides precipitates on Endurance Crater. Sedimentary deposits have been identified at Meridiani Planum. These deposits must have generated in a dune aqueous acidic and oxidizing environment. Similarities appear when we study Rio Tinto, and acidic river under the control of iron. The discovery of extremophiles on Earth widened the window of possibilities for life to develop in the Universe, and as a consequence on Mars and other planetary bodies with astrobiological interest. The compilation of data produced by the ongoing missions offers an interested view for life possibilities to exist: signs of an early wet Mars and rather recent volcanic activity as well as ground morphological characteristics that seem to be promoted by liquid water. The discovery of important accumulations of sulfates and the existence of iron minerals such as jarosite in rocks of sedimentary origin has allowed specific terrestrial models to come into focus. Río Tinto (Southwestern Spain, Iberian Pyritic Belt) is an extreme acidic environment, product of the chemolithotrophic activity of micro-organisms that thrive in the massive pyrite-rich deposits of the Iberian Pyritic Belt. Some particular protective environments should house the organic molecules and bacterial life forms in harsh environments such as Mars surface supporting microniches inside precipitated minerals or inside rocks. Terrestrial analogues could help us to afford the comprehension of habitability (on other planetary bodies). We are reporting here the multidisciplinary study of some endolithic niches inside salt deposits used by phototrophs for taking advantage of sheltering particular light wavelengths. These acidic salts deposits located in Río Tinto shelter life forms that are difficult to visualize by eye. This interdisciplinary field analogue campaign was conducted in the framework of the CAREX FP7 EC programme.","extreme environments; terrestrial analogues; astrobiology; field campaign","en","journal article","Cambridge University Press","","","","","","","2012-11-28","Aerospace Engineering","Remote Sensing","","","",""
"uuid:fe80fb9c-5981-4704-8393-c716f336ac33","http://resolver.tudelft.nl/uuid:fe80fb9c-5981-4704-8393-c716f336ac33","Aeroelastic tailoring using lamination parameters: Drag reduction of a Formula One rear wing","Thuwis, G.A.A.; De Breuker, R.; Abdalla, M.M.; Gürdal, Z.","","2009","The aim of the present work is to passively reduce the induced drag of the rear wing of a Formula One car at high velocity through aeroelastic tailoring. The angle-of-attack of the rear wing is fixed and is determined by the required downforce needed to get around a turn. As a result, at higher velocity, the amount of downforce and related induced drag increases. The maximum speed on a straight part is thus reduced due to the increase in induced drag. A fibre reinforced composite torsion box with extension-shear coupled upper and lower skins is used leading to bending-torsion coupling. Three-dimensional static aeroelastic analysis is performed loosely coupling the Finite Element code Nastran and the Computational Fluid Dynamics panel code VSAERO using ModelCenter. A wing representative of Formula One rear wings is optimised for minimum induced drag using a response surface methodology. Results indicate that a substantial induced drag reduction is achievable while maintaining the desired downforce during low speed turns.","aeroelastic tailoring; lamination parameters; drag reduction; automotive","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Structures & Design Methodology","","","",""
"uuid:498640ab-eb6e-4b1d-a73d-6a47b10e6435","http://resolver.tudelft.nl/uuid:498640ab-eb6e-4b1d-a73d-6a47b10e6435","Powering the skies; the evolution of the aircraft engine","Rao, A.; Van Buijtenen, J.; Van Tooren, M.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8fe13f5e-55df-407c-bd50-e75d06d52ee0","http://resolver.tudelft.nl/uuid:8fe13f5e-55df-407c-bd50-e75d06d52ee0","Static and dynamic angles of repose in loose granular materials under reduced gravity","Kleinhans, M.G.; Markies, H.; De Vet, S.J.; In 't Veld, A.C.; Postema, F.N.","","2011","Granular materials avalanche when a static angle of repose is exceeded and freeze at a dynamic angle of repose. Such avalanches occur subaerially on steep hillslopes and wind dunes and subaqueously at the lee side of deltas. Until now it has been assumed that the angles of repose are independent of gravitational acceleration. The objective of this work is to experimentally determine whether the angles of repose depend on gravity. In 33 parabolic flights in a well-controlled research aircraft we recorded avalanching granular materials in rotating drums at effective gravitational accelerations of 0.1, 0.38 and 1.0 times the terrestrial value. The granular materials varied in particle size and rounding and had air or water as interstitial fluid. Materials with angular grains had time-averaged angles of about 40° and with rounded grains about 25° for all effective gravitational accelerations, except the finest glass beads in air, which was explained by static electricity. For all materials, the static angle of repose increases about 5° with reduced gravity, whereas the dynamic angle decreases with about 10°. Consequently, the avalanche size increases with reduced gravity. The experimental results suggest that relatively low slopes of granular material on Mars may have formed by dry flows without a lubricating fluid. On asteroids even lower slopes are expected. The dependence on gravity of angle of repose may require reanalysis of models for many phenomena involving sediment, also at much lower slope angles.","Mars; angle of repose; asteroids; avalanche; parabolic flight","en","journal article","American Geophysical Union","","","","","","","2012-05-17","Aerospace Engineering","Control & Operations","","","",""
"uuid:848ca36e-0bff-4dbd-82ec-fc55b5fbf9d3","http://resolver.tudelft.nl/uuid:848ca36e-0bff-4dbd-82ec-fc55b5fbf9d3","Finding the edge, setting the limit; Orange Jumper, Royal Netherlands Air Force F-16 flight test aircraft","De Dooij, R.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9a4ee49e-657d-4c4f-ad29-8b09c423f4ff","http://resolver.tudelft.nl/uuid:9a4ee49e-657d-4c4f-ad29-8b09c423f4ff","Goal-Oriented Error Estimation and Adaptivity for Free-Boundary Problems: The Domain-Map Linearization Approach","Van der Zee, K.G.; Van Brummelen, E.H.; De Borst, R.","","2010","In free-boundary problems, the accuracy of a goal quantity of interest depends on both the accuracy of the approximate solution and the accuracy of the domain approximation. We develop duality-based a posteriori error estimates for functional outputs of solutions of free-boundary problems that include both sources of error. The derivation of an appropriate dual problem (linearized adjoint) is, however, nonobvious for free-boundary problems. To derive an appropriate dual problem, we present the domain-map linearization approach. In this approach, the free-boundary problem is first transformed into an equivalent problem on a fixed reference domain after which the dual problem is obtained by linearization with respect to the domain map. We show for a Bernoulli-type free-boundary problem that this dual problem corresponds to a Poisson problem with a nonlocal Robin-type boundary condition. Furthermore, we present numerical experiments that demonstrate the effectivity of the dual-based error estimate and its usefulness in goal-oriented adaptive mesh refinement.","goal-oriented error estimation; a posteriori error estimation; Bernoulli free-boundary problem; domain-map linearization; linearized adjoint; adaptive mesh refinement","en","journal article","Society for Industrial and Applied Mathematics","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:0dcb16d9-fb4f-479b-970c-0045df9fac36","http://resolver.tudelft.nl/uuid:0dcb16d9-fb4f-479b-970c-0045df9fac36","A decade of GPS in Southeast Asia: Resolving Sundaland motion and boundaries","Simons, W.J.F.; Socquet, A.; Vigny, C.; Ambrosius, B.A.C.; Haji Abu, S.; Promthong, C.; Subarya, C.; Sarsito, D.A.; Matheussen, S.; Morgan, P.; Spakman, W.","","2007","A unique GPS velocity field that spans the entire Southeast Asia region is presented. It is based on 10 years (1994–2004) of GPS data at more than 100 sites in Indonesia, Malaysia, Thailand, Myanmar, the Philippines, and Vietnam. The majority of the horizontal velocity vectors have a demonstrated global accuracy of ?1 mm/yr (at 95% confidence level). The results have been used to (better) characterize the Sundaland block boundaries and to derive a new geokinematic model for the region. The rotation pole of the undeformed core of the Sundaland block is located at 49.0°N–94.2°E, with a clockwise rotation rate of 0.34°/Myr. With respect to both geodetically and geophysically defined Eurasia plate models, Sundaland moves eastward at a velocity of 6 ± 1 to 10 ± 1 mm/yr from south to north, respectively. Contrary to previous studies, Sundaland is shown to move independently with respect to South China, the eastern part of Java, the island of Sulawesi, and the northern tip of Borneo. The Red River fault in South China and Vietnam is still active and accommodates a strike?slip motion of ?2 mm/yr. Although Sundaland internal deformation is general very small (less than 7 nanostrain/yr), important accumulation of elastic deformation occurs along its boundaries with fast?moving neighboring plates. In particular in northern Sumatra and Malaysia, inland?pointing trench?perpendicular residual velocities were detected prior to the megathrust earthquake of 26 December 2004. Earlier studies in Sumatra already showed this but underestimated the extent of the deformation zone, which reaches more than 600 km away from the trench. This study shows that only a regional Southeast Asia network spanning thousands of kilometers can provide a reference frame solid enough to analyze intraplate and interplate deformation in detail.","SE Asia; geodynamics; Sundaland; GEODYSSEA; SEAMERGES","en","journal article","American Geophysical Union","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:c7101eac-b98f-40d9-98f6-823d1da4b0f5","http://resolver.tudelft.nl/uuid:c7101eac-b98f-40d9-98f6-823d1da4b0f5","Design synthesis exercise 2013","","","2013","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:452f63c3-0abb-45c1-b5b3-7bab20a5cc77","http://resolver.tudelft.nl/uuid:452f63c3-0abb-45c1-b5b3-7bab20a5cc77","Aerospace industry down to earth; harnessing the future with knowledge based engineering","Van der Elst, S.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4a575a47-6b2e-4560-ac2d-0de5752a28e3","http://resolver.tudelft.nl/uuid:4a575a47-6b2e-4560-ac2d-0de5752a28e3","Conjugated poly(azomethine)s via simple one-step polycondensation chemistry: Synthesis, thermal and optoelectronic properties","Petrus, M.L.; Bouwer, R.K.M.; Lafont, U.; Murthy, D.H.K.; Kist, R.J.P.; Böhm, M.L.; Olivier, Y.; Savenije, T.J.; Siebbeles, L.D.A.; Greenham, N.C.; Dingemans, T.J.","","2013","Three conjugated triphenylamine-based poly(azomethine)s were prepared via well-known polycondensation chemistry using cheap and readily available starting materials and the results were contrasted with rrP3HT. Three functionalized diaminetriphenylamines (TPA(X), X ¼ –H, –OMe, –CN) were polymerized in a simple one-step process with 2,3-dihydrothieno[3,4-b][1,4]dioxine-5,7-dicarbaldehyde (ThOx), with water being the only side product. The resulting polymers (TPA(X)ThOx, X ¼ –H, –OMe, –CN) were characterized by GPC, IR and NMR, and show a good thermal stability. The opto-electronic properties could be tuned by changing the functionalization (X ¼ –H, –OMe, –CN) on the triphenylamine moiety. Photovoltaic devices based on TPA(X)ThOx/PCBM (1 : 2) showed power conversion efficiencies in the range of 0.02–0.04%. TRMC measurements showed that the presence of PCBM as an electron acceptor facilitates the formation of free mobile charges after excitation of the polymer. The low device efficiencies are attributed to a low hole-mobility of the polymer in combination with poor active layer morphology.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:4f8bee15-9f5e-40ef-ba61-a6daa2125bb5","http://resolver.tudelft.nl/uuid:4f8bee15-9f5e-40ef-ba61-a6daa2125bb5","Shockwave-boundary layer interactions","Glepman, R.","","2014","Shock wave-boundary layer interactions are a very common feature in both transonic and supersonic flows. They can be encountered on compressor and turbine blades, in supersonic jet inlets, on transonic wings, on the stabilization fins of missiles and in many more situations. Because of their major importance on the performance and safety of high-speed flight vehicles, they have now been studied for over 60 years, but their control remains challenging. This article presents the results of a study on a new type of flow control device: the micro-ramp vortex generator.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9b21e38f-7232-4d86-baac-ad61598020e6","http://resolver.tudelft.nl/uuid:9b21e38f-7232-4d86-baac-ad61598020e6","Counter-hairpin vortices in the turbulent wake of a sharp trailing edge","Ghaemi, S.; Scarano, F.","","2011","","boundary layer structure; free shear layers; turbulent boundary layers","en","journal article","Cambridge University Press","","","","","","","2012-11-28","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:381310a1-8583-41b6-b6f5-b7b6098edc2a","http://resolver.tudelft.nl/uuid:381310a1-8583-41b6-b6f5-b7b6098edc2a","The fastest bicycle in the world; how a team of Delft students is building a bicycle to break the world speed record","Annega, G.","","2011","The Netherlands is a country known for its extensive use of bicycles as a means of everyday transport. However, while it has existed for about two centuries, todays bicycles only differ from those of the 19th century in relatively small details. Human Power Team Delft is building a whole new type of bicycle with the potential to break the world speed record of 133 km/h.","bicycle; speed","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:683fd63b-753c-477d-85ca-7897112b1417","http://resolver.tudelft.nl/uuid:683fd63b-753c-477d-85ca-7897112b1417","V2G Thermal coupling analysis; internship assignment at DLR Göttingen","Maes, V.","","2014","When modelling a supersonic wind tunnel, such as the V2G (see Fig. 1), the tradeoff between affordable computations and accurate results drives much of current research. In all of DLR’s previous simulation attempts, inconsistencies were found when compared to the experimental data. To determine where the differences arose, detailed models of each stage were deemed necessary to validate boundary conditions. The first stage: the nozzle core.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a033d1bd-90ed-4557-b069-794140d7e7a2","http://resolver.tudelft.nl/uuid:a033d1bd-90ed-4557-b069-794140d7e7a2","Space debris; challenges and solutions","Van Beurden, E.; Prins, C.","","2013","Space debris has been a hot topic for the last few decades, ever since the space industry started growing exponentially. Everyone agrees that space debris is a growing problem and the saturation point has almost been reached. With a big risk of a chain reaction, called the Kessler syndrome, billions of euro’s worth of space equipment is at risk. Clearly something has to be done about this.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3f9e74f4-2074-4e1e-81b4-501b60f488ea","http://resolver.tudelft.nl/uuid:3f9e74f4-2074-4e1e-81b4-501b60f488ea","Influence of different wind profiles due to varying atmospheric stability on the fatigue life of wind turbines","Sathe, S.; Bierbooms, W.","","2007","","","en","journal article","IOP","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4a4fc050-6ae8-4c9b-b3a1-640b1d62277b","http://resolver.tudelft.nl/uuid:4a4fc050-6ae8-4c9b-b3a1-640b1d62277b","The future of commercial air transport; Jan van Toor, VP within EADS Corporate Technical Office CTO, gives a look into the future of aviation; interview","Van Zon, N.","","2013","Jan van Toor spends his time at EADS Innovation Works looking into the future, designing advanced concepts and initiating research efforts to analyse the feasibility and affordability of such a project. He recently visited the Faculty of Aerospace Engineering to give a lecture, and agreed to an interview with the Leonardo Times about the future of commercial air transport as EADS sees it unfolding over the next few decades.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:cc2575da-6907-4369-9ab5-353e45260f41","http://resolver.tudelft.nl/uuid:cc2575da-6907-4369-9ab5-353e45260f41","Airborne aerospace; interview with business development manager space","Nevinskala, A.; Gupta, S.","Woldendorp, S. (contributor)","2013","Airborne Composites designs and manufactures composite parts for the Aerospace, Oil & Gas, Marine and other industries since 1995. They are involved in notable hightech projects, from the Galileo Satellites, to the Gulfstream aircraft for Fokker and the ALMA astronomical telescope. The Leonardo Times sat down to talk to Sandor Woldendorp, Business Development Manager, Space division at Airborne to get an insight in the question: ‘’How do they do it?’’.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6f86f2cb-9f8a-4d57-aa24-ee4f55e6a9b9","http://resolver.tudelft.nl/uuid:6f86f2cb-9f8a-4d57-aa24-ee4f55e6a9b9","Hypersonic re-entry technology; insights into new advances in re-entry vehicles and materials","Sudmeijer, K.J.","","2013","We are already used to a widespread commercial utilization of spaceflight, particularly with satellites for communication, earth observation, navigation, weather forecast and many other applications. Launching satellites is a rather costly affair, particularly because twenty minutes after lift-off the greater part of the expensive part of the launcher is transferred into scrap on the bottom of the ocean.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2635d370-8646-42b6-b7ea-d53d5f89b715","http://resolver.tudelft.nl/uuid:2635d370-8646-42b6-b7ea-d53d5f89b715","A Time-Domain Fingerprint for BOC(m,n) Signals","Muth, B.; Oonincx, P.; Tiberius, C.","","2007","Binary offset carrier (BOC) describes a class of spread-spectrum modulations recently introduced for the next generation of global navigation satellite systems (GNSSs). The design strategies of these BOC signals have so far focused on the spectral properties of these signals. In this paper, we present a time-domain fingerprint for each BOC signal given by a unique histogram of counted time elapses between phase jumps in the signal. This feature can be used for classification and identification of BOC-modulated signals with unknown parameters.","","en","journal article","Hindawi Publishing Corporation","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4faee228-f21b-4f3e-841b-d7d849d90280","http://resolver.tudelft.nl/uuid:4faee228-f21b-4f3e-841b-d7d849d90280","Laddermill-sailing, Ship propulsion by wind energy independent from the wind direction!","Ockels, W.J.","","2006","","laddermill, wind energy","en","journal article","Delft University Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8f47097a-1f99-43dc-bcf7-805207f019c7","http://resolver.tudelft.nl/uuid:8f47097a-1f99-43dc-bcf7-805207f019c7","Phenological response of vegetation to upstream river flow in the Heihe Rive basin by time series analysis of MODIS data","Jia, L.; Shang, H.; Menenti, M.","","2011","","","en","journal article","Copernicus, GmbH","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a37d5efa-b74e-4466-adc4-5109e45037c8","http://resolver.tudelft.nl/uuid:a37d5efa-b74e-4466-adc4-5109e45037c8","The relationship between loads and power of a rotor and an actuator disc","Van Kuik, G.A.M.","","2014","Most state of the art rotor design methods are based on the actuator disc theory developed about one century ago. The actuator disc is an axisymmetric permeable surface carrying a load that represents the load on a real rotor with a finite number of blades N. However, the mathematics of the transition from a real rotor load to an axisymmetrically loaded disc is not yet presented in literature. By formulating an actuator disc equation of motion in which the Bernoulli constant H is expressed in kinematical terms, a comparison of the power conversion and load on the disc and rotor is possible. For both the converted power is expressed as a change of angular momentum times rotational speed. The limits for N ? ? while the chord c ? 0, the rotational speed ? ? ?, the load F becoming uniform by ?F/?r ? 0 and the thickness ? ? 0 confirm that the classical disc represents the rotor with an infinite number of blades. Furthermore, the expressions for the blade load are compared to the expressions in current design and analysis tools. The latter do not include the load on chord-wise vorticity. Including this is expected to give a better modelling of the tip and root flow.","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:5cdaa1cc-7bc9-4ecf-8277-ec06be3b3641","http://resolver.tudelft.nl/uuid:5cdaa1cc-7bc9-4ecf-8277-ec06be3b3641","Engineering soft nanostructured functional materials via orthogonal chemistry","Gromadzki, D.","","2010","Nanostructured amphiphilic block copolymers, graft copolymers, polymeric thermally responsive molecular brushes and polymer stars are only few examples of macromolecular architectures accessible either via controlled/living radical polymerization (CLRP) techniques or the combination of CLRP mechanisms with efficient post-polymerization routes including click chemistry. Precise control over the composition, molecular weight and functionalities is a prerequisite for soft polymeric materials to selforganize into ordered morphologies. This contribution describes novel orthogonal chemical routes for the synthesis of macromolecular architectures and selfassembly of functional soft polymeric materials. Emerging potential applications of well-defined block and graft copolymers are outlined as well.","Polymerization; Self-assembly; Nanostructured functional polymers","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:680cd144-4cdd-4c45-8bd7-2a6d052a359e","http://resolver.tudelft.nl/uuid:680cd144-4cdd-4c45-8bd7-2a6d052a359e","The optimum expression for the gravitational potential of polyhedral bodies having a linearly varying density distribution","Prutkin, I.; Tenzer, R.","","2009","When topography is represented by a simple regular grid digital elevation model, the analytical rectangular prism approach is often used for a precise gravity field modelling at the vicinity of the computation point. However, when the topographical surface is represented more realistically, for instance by a triangular irregular network (TIN) model, the analytical integration using arbitrary polyhedral bodies (the analytical line integral approach) can be implemented directly without additional data pre-processing (gridding or interpolation). The analytical line integral approach can also facilitate 3-D density models created for complex geometrical bodies. For the forward modelling of the gravitational field generated by the geological structures with variable densities, the analytical integration can be carried out using polyhedral bodies with a varying density. The optimal expression for the gravitational attraction vector generated by an arbitrary polyhedral body having a linearly varying density is known. In this article, the corresponding optimal expression for the gravitational potential is derived by means of line integrals after applying the Gauss divergence theorem.","Gravitational potential; Line integral; Linear density; Polyhedron","en","journal article","Springer","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","","",""
"uuid:95328913-f2c4-46ec-9b92-16fb349ae85d","http://resolver.tudelft.nl/uuid:95328913-f2c4-46ec-9b92-16fb349ae85d","Design definition and Manufacturing of the Superbus","Terzi, A.; Antonelli, V.; Ockels, W.J.","","2007","In this paper the structural design and the manufacturing aspects of the Superbus (Fig. 1) are presented. First the major aspects of the structural design are described alongside with the FEM model utilized. Then the materials utilized will be highlighted. Finally, the manufacturing of the various parts, namely chassis, bodywork and glazing will be described.","Superbus","en","journal article","SAE International","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:5e20a1e1-7180-4a5e-b154-df31ccd3825b","http://resolver.tudelft.nl/uuid:5e20a1e1-7180-4a5e-b154-df31ccd3825b","Ambiguity Resolution for Permanent Scatterer Interferometry","Kampes, B.M.; Hanssen, R.F.","","2004","In the permanent scatterer technique of synthetic aperture radar interferometry, there is a need for an efficient and reliable nonlinear parameter inversion algorithm that includes estimation of the phase cycle ambiguities. Present techniques make use of a direct search of the solution space, treating the observations as deterministic and equally weighted, and which do not yield an exact solution. Moreover, they do not describe the quality of the estimated parameters. Here, we use the integer least squares estimator, which has the highest probability of correct integer estimation for problems with a multivariate normal distribution. With this estimator, the propagated variance-covariance matrix of the estimated parameters can be obtained. We have adapted the LAMBDA method, part of an integer least squares estimator developed for the ambiguity resolution of carrier phase observations in global positioning systems, to the problem of permanent scatterers. Key elements of the proposed method are the introduction of pseudo-observations to regularize the system of equations, decorrelation of the ambiguities for an efficient estimation, and the combination of a bootstrap estimator with an integer least squares search to obtain the final integer estimates. The performance of the proposed algorithm is demonstrated using simulated and real data.","nonlinear parameter inversion; permanent scatterers; synthetic aperture radar (SAR) interferometry","en","journal article","IEEE","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:05430737-8097-4ec6-bf65-bc0676bbbb36","http://resolver.tudelft.nl/uuid:05430737-8097-4ec6-bf65-bc0676bbbb36","Comparison of aerodynamic models for Vertical Axis Wind Turbines","Simao Ferreira, C.J.; Aagaard Madsen, H.; Barone, M.; Roscher, B.; Deglaire, P.; Arduin, I.","","2014","Multi-megawatt Vertical Axis Wind Turbines (VAWTs) are experiencing an increased interest for floating offshore applications. However, VAWT development is hindered by the lack of fast, accurate and validated simulation models. This work compares six different numerical models for VAWTS: a multiple streamtube model, a double-multiple streamtube model, the actuator cylinder model, a 2D potential flow panel model, a 3D unsteady lifting line model, and a 2D conformal mapping unsteady vortex model. The comparison covers rotor configurations with two NACA0015 blades, for several tip speed ratios, rotor solidity and fixed pitch angle, included heavily loaded rotors, in inviscid flow. The results show that the streamtube models are inaccurate, and that correct predictions of rotor power and rotor thrust are an effect of error cancellation which only occurs at specific configurations. The other four models, which explicitly model the wake as a system of vorticity, show mostly differences due to the instantaneous or time averaged formulation of the loading and flow, for which further research is needed.","","en","journal article","IOP Publishing","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:fbbf2655-c7f9-43da-8b34-3796f29bce56","http://resolver.tudelft.nl/uuid:fbbf2655-c7f9-43da-8b34-3796f29bce56","Erasmus Mundus European Wind Energy Master; a new MSc programme between four world-leading universities in wind energy","Cool, G.","","2012","","EWEM","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:46fc71d0-55f5-4611-bd00-71ffbff24bbb","http://resolver.tudelft.nl/uuid:46fc71d0-55f5-4611-bd00-71ffbff24bbb","Die Kraft des Drachens","Schmehl, R.","","2011","Der Großteil atmosphärischer Windenergie ist mit normalen Turbinen unerreichbar. Schnell fliegende Lenkdrachen könnten sie ernten.","","de","journal article","","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:feb3ce7b-e6f8-4d04-a6c1-1dad6ef05221","http://resolver.tudelft.nl/uuid:feb3ce7b-e6f8-4d04-a6c1-1dad6ef05221","An automated approach for solution based mesh adaptation to enhance numerical accuracy for a given number of grid cells","Lucas, P.; Van Zuijlen, A.H.; Bijl, H.","","2009","Mesh adaptation is a fairly established tool to obtain numerically accurate solutions for flow problems. Computational efficiency is, however, not always guaranteed for the adaptation strategies found in literature. Typically excessive mesh growth diminishes the potential efficiency gain. This paper, therefore, extends the strategy proposed by [Aftosmis and Berger (2002)] to compute the refinement threshold. The extended strategy computes the refinement threshold based on a user desired number of grid cells and adaptations, thereby ensuring high computational efficiency. Because our main interest is flow around wind turbines, the adaptation strategy has been optimized for flow around wind turbine airfoils. The proposed strategy was found to yield computationally efficient computations for flow around wind turbine airfoils as well as for other flow problems.","solution based mesh adaptation; computation refinement threshold; hexahedral grids; computational efficiency","en","journal article","Tech Science Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0be9e2fc-d987-4743-99b9-c1d4b7a9aea2","http://resolver.tudelft.nl/uuid:0be9e2fc-d987-4743-99b9-c1d4b7a9aea2","The Bell X-1; the first plane ever that flew faster than the speed of sound","Bavelaar, E.; Van Veen, L.","","2010","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8ad5dd66-b04d-477c-bceb-26185d34ef00","http://resolver.tudelft.nl/uuid:8ad5dd66-b04d-477c-bceb-26185d34ef00","Piezoelectric and mechanical properties of structured PZT–epoxy composites","Kunnamkuzhakkal James, N.; Van den Ende, D.; Lafont, U.; Van der Zwaag, S.; Groen, W.A.","","2013","Structured lead zirconium titanate (PZT)–epoxy composites are prepared by dielectrophoresis. The piezoelectric and dielectric properties of the composites as a function of PZT volume fraction are investigated and compared with the corresponding unstructured composites. The effect of poling voltage on piezoelectric properties of the composites is studied for various volume fractions of PZT composites. The experimentally observed piezoelectric and dielectric properties have been compared with theoretical models. Dielectrophoretically structured composites exhibit higher piezoelectric voltage coefficients compared to 0–3 composites. Structured composites with 0.1 volume fraction of PZT have the highest piezoelectric voltage coefficient. The flexural strength and bending modulus of the structured and random composites were analyzed using three-point bending tests.","dielectric properties; piezoelectric; ceramic","en","journal article","Materials Research Society","","","","","","","2014-02-01","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:0b01577a-d4e5-4f50-bf3f-8c10de214460","http://resolver.tudelft.nl/uuid:0b01577a-d4e5-4f50-bf3f-8c10de214460","Vegetation response to upstream water yield in the Heihe River by time series analysis of MODIS data","Jia, L.I.; Shang, H.; Menenti, M.","","2010","Liquid and solid precipitation is abundant in the high elevation, upper reach of the Heihe basin. The development of modern irrigation schemes in the middle reach of the basin is taking up an increasing share of fresh water resources, endangering the oasis and traditional irrigation systems in the lower reach. In this study, the response of vegetation in the Ejina Oasis in the lower reach of the Heihe River to the water yield of the upper catchment was analyzed by time series analysis of monthly observations of precipitation in the upper and lower catchment, river streamflow downstream of the modern irrigation schemes and satellite observations of vegetation index. Firstly, remote sensing data were used to monitor the vegetation dynamic for a long time period. Due to cloud-contamination, atmospheric influence and different solar angles, however, the quality and consistence of time series of remote sensing data is degraded. In this research we used a Fourier Transform method – the Harmonic Analysis of Time Series (HANTS) algorithm – to reconstruct cloud-free NDVI time series data from the Terra-MODIS dataset. Anomalies in precipitation, streamflow, and vegetation index are detected by comparing each year with the average year. The relationship between the anomalies in vegetation growth, the local precipitation and upstream water yield were analyzed. The same approach is used to identify, remove and gap-filling cloud contaminated observations in the satellite data for each year in the dataset. The results showed that: the previous year total runoff had a significant relationship with the vegetation growth in Ejina Oasis and that anomalies in monthly runoff of the Heihe River influenced the phenology of vegetation in the entire oasis during drier years. The time of maximum green-up was uniform throughout the oasis during wetter years, but showed a clear S–N gradient (downstream) during drier years.","","en","journal article","European Geosciences Union","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:5853c14d-af84-48a1-bdbf-e27f8d597056","http://resolver.tudelft.nl/uuid:5853c14d-af84-48a1-bdbf-e27f8d597056","A new dean in town; an interview with the new dean, Professor Hester Bijl","Spranger, L.; Broekhuizen, B.","","2013","On April 15, Professor Hester Bijl was officially appointed the new dean of the Faculty of Aerospace Engineering. Succeeding Professor Jacco Hoekstra, she became the first female dean of the faculty. She is a Delft alumnus who has worked in both business and academia. Ample reason for the Leonardo Times to sit down for an interview with Professor Bijl.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ec0c778f-64d8-4705-b646-a7ba6958b145","http://resolver.tudelft.nl/uuid:ec0c778f-64d8-4705-b646-a7ba6958b145","Response surface based optimization; gradient-enhanced kriging of a high-pressure turbine","Huijbregts, F.","","2014","In the Aerospace industry, before the construction of a new aircraft or engine is even realized, its performance and characteristics are already known. This knowledge is obtained through simulations in a wind-tunnel or using computational fl uid dynamics. But with complex aircraft and engines, the use of these simulations can be limited by the computational means that are available. For this master thesis, the application of surrogate modeling, with the design of turbines of aero-engines is studied. This master thesis was performed with Rolls-Royce Deutschland.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:dfa1ce22-8701-4026-ba51-81b4f2e68f0e","http://resolver.tudelft.nl/uuid:dfa1ce22-8701-4026-ba51-81b4f2e68f0e","An aviation entrepreneur gets into space; an interview with Martin Schröder, founder of Martinair","Bavelaar, E.; Schneiders, J.; Wormer, M.","","2010","","Martinair; Martin Schröder","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3bd7b897-2206-479d-a712-93ea5e9732c7","http://resolver.tudelft.nl/uuid:3bd7b897-2206-479d-a712-93ea5e9732c7","Towards Understanding Fatigue Disbond Growth via Cyclic Strain Energy","Pascoe, J.A.; Alderliesten, R.C.; Benedictus, R.","","2014","The concept of relating fatigue disbond growth to the strain energy release rate (SERR) is critically examined. It is highlighted that the common practise of using only the maximum SERR or only the SERR range is insufficient to correctly characterize a load cycle. As crack growth requires energy, it is argued that growth should be related to the total amount of energy released during a fatigue cycle, and not to the amount of energy that would be released by a crack growth increment under the instantaneous load conditions at one point in the load cycle. This argument is supported by experimental evidence, showing that the relationship between fatigue disbond growth (FDG) rate and either maximum SERR or SERR range is R-ratio dependent, whereas the relationship between FDG rate and the loss of strain energy is not.","adhesive Bonding; fatigue; disbond growth; energy method","en","journal article","Elsevier","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:aee9155a-316f-42bc-b67f-bd65d9e62646","http://resolver.tudelft.nl/uuid:aee9155a-316f-42bc-b67f-bd65d9e62646","Attitude estimation of the Delfi-n3Xt satellite","Choukroun, D.; Maas, A.; Kuiper, J.M.","","2013","This paper presents current developments of the attitude determination algorithm for Del¦-n3Xt, TU Delft next nanosatellite. Several novel quaternion filters using Sun vector and Earth magnetic field measurements and rate gyro outputs are presented. The quaternion measurement matrix associated with each line-of-sight measurement is shown to be rank deficient. This property is exploited in order to design reduced order measurement update stages in the filters. The measurement model reduction is designed such as to preserve the statistical information. The filter covariance propagation can cope rigorously with the multiplicative process noises. The paper also describes the development of the Sun vector determination algorithm, which merges the outputs of 6 body-mounted four-quadrant Sun sensors. For each sensor, a simple algorithm allows Sun vector determination while avoiding the use of uncertain physical parameters. This algorithm takes into account geometrical imperfections linked to manufacturing limitations. A thorough error analysis of the photodiodes measurement outputs is carried out. A spacecraft Sun vector determination algorithm is proposed and illustrated, in the absence of Earth albedo effect, via Monte-Carlo simulations and experimental validation. In addition, extensive Monte-Carlo simulations illustrate the good performances of the quaternion filters using spacecraft Sun vector and Earth magnetic field measurements. The novel reduced filter shows good performances in a challenging tumbling dynamics environment, where a standard additive Kalman filter fails to converge.","","en","journal article","EDP sciences","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:bac48ae3-3973-468a-b6de-104b662ac6a4","http://resolver.tudelft.nl/uuid:bac48ae3-3973-468a-b6de-104b662ac6a4","Storage selection functions: A coherent framework for quantifying how catchments store and release water and solutes","Rinaldo, A.; Benettin, P.; Harman, C.J.; Hrachowitz, M.; McGuire, K.J.; Van der Velde, Y.; Bertuzzo, E.; Botter, G.","","2015","We discuss a recent theoretical approach combining catchment-scale flow and transport processes into a unified framework. The approach is designed to characterize the hydrochemistry of hydrologic systems and to meet the challenges posed by empirical evidence. StorAge Selection functions (SAS) are defined to represent the way catchment storage supplies the outflows with water of different ages, thus regulating the chemical composition of out-fluxes. Biogeochemical processes are also reflected in the evolving residence time distribution and thus in age-selection. Here we make the case for the routine use of SAS functions and look forward to areas where further research is needed.","","en","journal article","American Geophysical Union","","","","","","","2015-12-30","Aerospace Engineering","Control & Operations","","","",""
"uuid:8bcb42e6-6536-4fe0-a310-9e574a078535","http://resolver.tudelft.nl/uuid:8bcb42e6-6536-4fe0-a310-9e574a078535","Simulation of tension fields with in-plane rotational degrees of freedom","Pagitz, M.; Abdalla, M.","","2010","This paper introduces a novel multigrid approach for the geometric non-linear simulation of tension fields on the basis of a three-node membrane finite element. The element possesses, in addition to the nodal displacement degrees of freedom, an in-plane rotational degree of freedom inside the element domain that controls the direction of the tension field. This rotational degree of freedom allows the enforcement of continuity and tension field boundary conditions on the basis of a coarser mesh with varying size.","Membrane; Wrinkling; Multigrid; Finite element","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Structures & Design Methodology","","","",""
"uuid:4f491cc5-cdc7-49b4-8b80-700dae2cf57c","http://resolver.tudelft.nl/uuid:4f491cc5-cdc7-49b4-8b80-700dae2cf57c","Validity improvement of evolutionary topology optimization: Procedure with element replaceable method","Zhu, J.; Zhang, W.; Bassir, D.H.","","2009","The aim of this paper is to enhance the validity of existing evolutionary topology optimization procedures. As this hard-killing scheme related to the element sensitivity values may lead to incorrect predictions of inefficient elements to be removed and the value of the objective function becomes sharply deteriorated during the iterations, a check position (CP) control is proposed to prevent the erroneous topology design generated by the rejection criteria of evolutionary methods. For this purpose, we introduce a sort of orthotropic cellular microstructure (OCM) element with moderate pseudodensity that acts as a compromising element between solid element and void OCM element. In this way, all inefficient elements removed previously are automatically replaced with the moderate OCM elements depending upon the deterioration of the objective function. Erroneously removed elements are then identified in the updated finite element model through a direct sensitivity computing of the moderate OCM elements and will be finally recovered by the bi-directional element replacement. Besides, detailed structures with checkerboard patterns are eliminated by controlling the local structural bandwidth with the so-called threshold method. Typical optimization examples of structural compliance and natural frequency that were difficult to tackle are solved by the proposed design procedure. Satisfactory numerical results are obtained.","optimization; evolutionary method; erroneous design; check position control; moderate microstructure","en","journal article","EDP sciences","","","","","","","","Aerospace Engineering","Aerospace Structures","","","",""
"uuid:2f81cd45-0de3-4586-acac-02e7ca015692","http://resolver.tudelft.nl/uuid:2f81cd45-0de3-4586-acac-02e7ca015692","Precise and faster GNSS signal direction of arrival estimation","Sun, R.; O'Keefe, K.; Guo, J.; Gill, E.","","2013","This paper proposes a precise and fast direction of arrival estimation method using Global Navigation Satellite System (GNSS) carrier phase measurements. Single-epoch, single-satellite integer cycle ambiguities are reliably resolved by making use of constraints and taking advantages of antenna arrays. The algorithm shows good robustness in cases where signal interruption or corruption occurs on some antenna elements as long as four antenna elements in a non-planar array have uncorrupted observables. The algorithm is demonstrated by field tests where antenna elements are connected to multiple receivers with an external common clock. The results indicate a high success rate of single-epoch ambiguity resolution and high direction of arrival accuracy.","signal direction of arrival; ambiguity resolution; constraint; antenna array","en","journal article","Cambridge University Press","","","","","","","2014-08-01","Aerospace Engineering","Space Engineering","","","",""
"uuid:15adddbd-bab0-43f5-b10d-9cbb999ee539","http://resolver.tudelft.nl/uuid:15adddbd-bab0-43f5-b10d-9cbb999ee539","Optimization of a variable-stiffness skin for morphing high-lift devices","Thuwis, G.A.A.; Abdalla, M.M.; Gürdal, Z.","","2010","One of the possibilities for the next generation of smart high-lift devices is to use a seamless morphing structure. A passive composite variable-stiffness skin as a solution to the dilemma of designing the structure to have high enough stiffness to withstand aerodynamic loading and low stiffness to enable morphing is proposed. The variable-stiffness skin is achieved by allowing for a spatial fibre angle and skin thickness variation on a morphing high-lift system. The stiffness distribution is tailored to influence the deformation of the structure beneficially. To design a realistic stiffness distribution, it is important to take aerodynamic and actuation loads into account during the optimization. A two-dimensional aero-servo-elastic framework is created for this purpose. Skin optimization is performed using a gradient-based optimizer, where sensitivity information is found through application of the adjoint method. The implementation of the aero-servo-elastic environment is addressed and initial optimization results presented. The results indicate that a variable-stiffness skin increases the design space. Moreover, the importance of taking the change in aerodynamic loads due to morphing skin deformation into account during optimization is demonstrated.","","en","journal article","Institute of Physics","","","","","","","","Aerospace Engineering","Department of Aerospace Structures","","","",""
"uuid:9eba6300-9277-4b0e-90db-5d0d23daa473","http://resolver.tudelft.nl/uuid:9eba6300-9277-4b0e-90db-5d0d23daa473","The story of a rocketplane test pilot; interview with Rick Searfoss","Motsyk, O.","","2012","","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:932c08a5-7cf6-4897-9833-503d6ecf0f54","http://resolver.tudelft.nl/uuid:932c08a5-7cf6-4897-9833-503d6ecf0f54","High-resolution PIV measurements of a transitional shock wave–boundary layer interaction","Giepman, R.H.M.; Schrijer, F.F.J.; Van Oudheusden, B.W.","","2015","This study investigates the effects of boundary layer transition on an oblique shock wave reflection. The Mach number was 1.7, the unit Reynolds number was 35 × 106 m?1, and the pressure ratio over the interaction was 1.35. Particle image velocimetry is used as the main flow diagnostics tool, supported by oil-flow and Schlieren visualizations. At these conditions, the thickness of the laminar boundary layer is only 0.2 mm, and seeding proved to be problematic as practically no seeding was recorded in the lower 40 % of the boundary layer. The top 60 % could, however, still be resolved with good accuracy and is found to be in good agreement with the compressible Blasius solution. Due to the effects of turbulent mixing, the near-wall seeding deficiency disappears when the boundary layer transitions to a turbulent state. This allowed the seeding distribution to be used as an indicator for the state of the boundary layer, permitting to obtain an approximate intermittency distribution for the boundary layer transition region. This knowledge was then used for positioning the oblique shock wave in the laminar, transitional (50 % intermittency) or turbulent region of the boundary layer. Separation is only recorded for the laminar and transitional interactions. For the laminar interaction, a large separation bubble is found, with a streamwise length of 96 ??i,0 . The incoming boundary layer is lifted over the separation bubble and remains in a laminar state up to the impingement point of the shock wave. After the shock, transition starts and a turbulent profile is reached approximately 80–90 ??i,0 downstream of the shock. Under the same shock conditions, the transitional interaction displays a smaller separation bubble (43 ??i,0 ), and transition is found to be accelerated over the separation bubble.","","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:b635a0a8-2ca1-44ae-8fbc-0866b3304827","http://resolver.tudelft.nl/uuid:b635a0a8-2ca1-44ae-8fbc-0866b3304827","Model-based sediment classification using single-beam echosounder signals","Snellen, M.; Siemes, K.; Simons, D.G.","","2011","Acoustic remote sensing techniques for mapping sediment properties are of interest due to their low costs and high coverage. Model-based approaches directly couple the acoustic signals to sediment properties. Despite the limited coverage of the single-beam echosounder (SBES), it is widely used. Having available model-based SBES classification tools, therefore, is important. Here, two modelbased approaches of different complexity are compared to investigate their practical applicability. The first approach is based on matching the echo envelope. It maximally exploits the information available in the signal but requires complex modeling and optimization. To minimize computational costs, the efficient differential evolution method is used. The second approach reduces the information of the signal to energy only and directly relates this to the reflection coefficient to obtain quantitative information about the sediment parameters. The first approach provides information over a variety of sediment types. In addition to sediment mean grain size, it also provides estimates for the spectral strength and volume scattering parameter. The need to account for all three parameters is demonstrated, justifying computational expenses. In the second approach, the lack of information on these parameters and the limited SBES beamwidth are demonstrated to hamper the conversion of echo energy to reflection coefficient.","","en","journal article","Acoustical Society of America","","","","","","","2011-11-30","Aerospace Engineering","Remote Sensing","","","",""
"uuid:e22dcf36-b9be-4b7a-b7fa-4626e8d5f393","http://resolver.tudelft.nl/uuid:e22dcf36-b9be-4b7a-b7fa-4626e8d5f393","Methods for the prediction of fatigue delamination growth in composites and adhesive bonds: A critical review","Pascoe, J.A.; Alderliesten, R.C.; Benedictus, R.","","2013","An overview is given of the development of methods for the prediction of fatigue driven delamination growth over the past 40 years. Four categories of methods are identified: stress/strain-based models, fracture mechanics based models, cohesive-zone models, and models using the extended finite element method. It is highlighted that most models are phenomenological, based on the observed macro-scale behaviour of test specimens. It is suggested that a more physics based approach, focusing on elucidating the mechanisms involved, is needed to come to a full understanding of the problem of delamination growth.","delamination; fatigue; linear elastic fracture mechanics; cohesive zone model; XFEM","en","journal article","Elsevier","","","","","","","2013-11-07","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:b863131a-6b58-462e-94de-eff030a95071","http://resolver.tudelft.nl/uuid:b863131a-6b58-462e-94de-eff030a95071","Higher period stochastic bifurcation of nonlinear airfoil fluid-structure interaction","Witteveen, J.A.S.; Bijl, H.","","2009","","","en","journal article","Hindawi","","","","","","","","Aerospace Engineering","","","","",""
"uuid:bfc300fd-9ef5-4477-afa4-4707194dd1d5","http://resolver.tudelft.nl/uuid:bfc300fd-9ef5-4477-afa4-4707194dd1d5","Bicycle network needs, solutions, and data collection systems: A theoretical framework and case studies","Reggiani, G. (TU Delft Transport and Planning); Salomons, A.M. (TU Delft Transport and Planning); Sterk, M.A.H. (TU Delft Aerospace Engineering); O'Hern, Steve (Tampere University); Daamen, W. (TU Delft Transport and Planning); Yuan, Y. (TU Delft Transport and Planning); Hoogendoorn, S.P. (TU Delft Transport and Planning)","","2022","Similarly to Maslow’s pyramid of human needs, we theorize that cities have a pyramid of bicycle network needs that depends on their level of bicycle culture. As an increasing number of data sources emerge for bicycle data collection, transport authorities face the challenge of understanding how to use the data and which data sources are fit for their network needs. This article defines a framework that relates the bicycle network needs of cities with data collection systems. We showcase the need-driven framework through a case study of Melbourne, Australia, a bicycle ignorant city, and surveying 15 municipalities (and their consultancies) of the Netherlands. By using the proposed need-driven framework cities can understand how to fully exploit bicycle data collection systems and make a systematic plan.","Bicycle data collection system; Nation-wide surve; Bicycle network needs","en","journal article","","","","","","","","","Aerospace Engineering","Transport and Planning","Transport and Planning","","",""
"uuid:6a3d1ca1-950b-43d5-9789-0b892ec40f16","http://resolver.tudelft.nl/uuid:6a3d1ca1-950b-43d5-9789-0b892ec40f16","Integration methods for distributed sound sources","Merino Martinez, R. (TU Delft Aircraft Noise and Climate Effects); Sijtsma, P. (TU Delft Aircraft Noise and Climate Effects); Rubio Carpio, A. (TU Delft Aircraft Noise and Climate Effects); Zamponi, R. (von Karman Institute for Fluid Dynamics); Luesutthiviboon, S. (TU Delft Aerospace Engineering); Malgoezar, A.M.N. (TU Delft Aircraft Noise and Climate Effects); Snellen, M. (TU Delft Aircraft Noise and Climate Effects); Schram, Christophe (von Karman Institute for Fluid Dynamics); Simons, D.G. (TU Delft Aircraft Noise and Climate Effects)","","2019","Most acoustic imaging methods assume the presence of point sound sources and, hence, may fail to correctly estimate the sound emissions of distributed sound sources, such as trailing-edge noise. In this contribution, three integration techniques are suggested to overcome this issue based on models considering a single point source, a line source, and several line sources, respectively. Two simulated benchmark cases featuring distributed sound sources are employed to compare the performance of these integration techniques with respect to other well-known acoustic imaging methods. The considered integration methods provide the best performance in retrieving the source levels and require short computation times. In addition, the negative effects of the presence of unwanted noise sources, such as corner sources in wind-tunnel measurements, can be eliminated. A sensitivity analysis shows that the integration technique based on a line source is robust with respect to the choice of the integration area (shape, position, and mesh fineness). This technique is applied to a trailing-edge-noise experiment in an open-jet wind tunnel featuring a NACA 0018 airfoil. The location and far-field noise emissions of the trailing-edge line source were calculated.","Acoustic imaging; integration methods; porous trailing edge; trailing-edge noise","en","journal article","","","","","","","","","Aerospace Engineering","","Aircraft Noise and Climate Effects","","",""
"uuid:5c5c5853-4abd-4465-8364-2f85515773e1","http://resolver.tudelft.nl/uuid:5c5c5853-4abd-4465-8364-2f85515773e1","Design and Experimental Validation of Swirl Recovery Vanes for Propeller Propulsion Systems","Li, Q. (TU Delft Flight Performance and Propulsion); Öztürk, K. (TU Delft Aerospace Engineering); Ragni, D. (TU Delft Wind Energy); Sinnige, T. (TU Delft Flight Performance and Propulsion); Eitelberg, G. (TU Delft Flight Performance and Propulsion); Veldhuis, L.L.M. (TU Delft Flight Performance and Propulsion); Yangang, Wang (Northwestern Polytechnical University)","","2018","The momentum transferred to the fluid by a running propeller contains not only the desired axial component but also a rotational component that does not contribute to the propeller thrust. By introducing a set of swirl-recovery vanes (SRVs) downstream of the propeller, part of the rotational flow in the slipstream can be redirected into the streamwise direction, thereby producing extra thrust and enhancing the propulsive efficiency. The current study presents the development, application, and experimental validation of a low-order SRV design tool. The design method combines a short computational time with a detailed vane-shape representation. The procedure is presented together with a test example, consisting of a set of SRVs designed and manufactured for operation with a six-bladed propeller operating at thrust coefficient of CT;P _ 0.32. Results from the computations are subsequently validated by a wind-tunnel experiment with the propeller–SRV model. The SRVs were shown to provide extra thrust at all the considered propeller operating conditions. Because the installation of the SRVs does not lead to an increase in power consumption, it is thus shown that SRVs have the potential to increase the propulsive efficiency during all phases of the flight.","","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-03-28","Aerospace Engineering","","Flight Performance and Propulsion","","",""
"uuid:01955ba2-a841-49e8-bb5d-a6c9c5262514","http://resolver.tudelft.nl/uuid:01955ba2-a841-49e8-bb5d-a6c9c5262514","The Faculty of Aerospace Engineering at Delft University of Technology","De Breuker, R. (TU Delft Aerospace Structures & Computational Mechanics); Benedictus, R. (TU Delft Structural Integrity & Composites); Bisagni, C. (TU Delft Aerospace Structures & Computational Mechanics); Boneschansker, I. (TU Delft Communication LR); Melkert, J.A. (TU Delft Flight Performance and Propulsion); Snellen, M. (TU Delft Control & Operations; TU Delft Aircraft Noise and Climate Effects); Veldhuis, L.L.M. (TU Delft Flow Physics and Technology; TU Delft Flight Performance and Propulsion); Verdegaal, F.M. (TU Delft Support Aerospace Engineering); Visser, P.N.A.M. (TU Delft Space Engineering; TU Delft Space Systems Egineering); Werij, H.G.C. (TU Delft Aerospace Engineering)","","2022","The Faculty of Aerospace Engineering is one of eight faculties at Delft University of Technology. It is one of the most comprehensive academic and innovation communities worldwide focusing on aerospace engineering. Its 120 professors and 70 researchers are mentoring and teaching around 2,800 BSc/MSc students and more than 350 PhD candidates while working in all aerospace disciplines. It’s a powerhouse in aerospace education, research, and innovation, within the top 10 in the world. Our priority themes? Sustainable aerospace, digital transformation, including Artificial Intelligence, bio-inspired engineering and smart instruments and systems. Here’s our story.","TU Delft; aerospace","en","journal article","","","","","","","","","Aerospace Engineering","Control & Operations","Aerospace Structures & Computational Mechanics","","",""
"uuid:1d43ce35-440d-4d14-96ff-aaf9488b4018","http://resolver.tudelft.nl/uuid:1d43ce35-440d-4d14-96ff-aaf9488b4018","A new dawn of aviation","Werij, H.G.C. (TU Delft Aerospace Engineering)","","2019","To counter the climate effects of flying, we must start a revolution in aviation.
Solutions must and will be found. I believe we’re at a new dawn of aviation.","","en","journal article","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5c6513c3-32d3-41fb-8b8e-a5e591a3218f","http://resolver.tudelft.nl/uuid:5c6513c3-32d3-41fb-8b8e-a5e591a3218f","Embodied airflow sensing for improved in-gust flight of flapping wing MAVs","Wang, C. (TU Delft Aerospace Engineering); Wang, S. (TU Delft Control & Simulation); de Croon, G.C.H.E. (TU Delft Control & Simulation); Hamaza, S. (TU Delft Control & Simulation)","","2022","Flapping wing micro aerial vehicles (FWMAVs) are known for their flight agility and maneuverability. These bio-inspired and lightweight flying robots still present limitations in their ability to fly in direct wind and gusts, as their stability is severely compromised in contrast with their biological counterparts. To this end, this work aims at making in-gust flight of flapping wing drones possible using an embodied airflow sensing approach combined with an adaptive control framework at the velocity and position control loops. At first, an extensive experimental campaign is conducted on a real FWMAV to generate a reliable and accurate model of the in-gust flight dynamics, which informs the design of the adaptive position and velocity controllers. With an extended experimental validation, this embodied airflow-sensing approach integrated with the adaptive controller reduces the root-mean-square errors along the wind direction by 25.15% when the drone is subject to frontal wind gusts of alternating speeds up to 2.4 m/s, compared to the case with a standard cascaded PID controller. The proposed sensing and control framework improve flight performance reliably and serve as the basis of future progress in the field of in-gust flight of lightweight FWMAVs.","flapping wing MAV; bio-inspired sensing; adaptive control; in-gust flight; onboard airflow sensing","en","journal article","","","","","","","","","Aerospace Engineering","","Control & Simulation","","",""
"uuid:6c08b9ff-1694-492a-ac33-913d69c6e85b","http://resolver.tudelft.nl/uuid:6c08b9ff-1694-492a-ac33-913d69c6e85b","3D Printing Concrete on temporary surfaces: The design and fabrication of a concrete shell structure","Borg Costanzi, C. (TU Delft Design of Constrution; Eindhoven University of Technology); Ahmed, Z. Y. (Eindhoven University of Technology; Student TU Delft); Schipper, H.R. (TU Delft Applied Mechanics; Eindhoven University of Technology); Bos, F. (TU Delft Education AE; Eindhoven University of Technology); Knaack, U. (TU Delft Design of Constrution; Eindhoven University of Technology); Wolfs, R.J.H. (TU Delft Aerospace Engineering; Eindhoven University of Technology)","","2018","One of the geometrical restrictions associated with printed paste materials such as concrete, is that material must be self-supporting during printing. In this research paper a new methodology for 3D Printing Concrete onto a temporary freeform surface is presented. This is achieved by setting up a workflow for combining a Flexible Mould developed at TU Delft with a 4-degrees-of-freedom gantry printer (4 DOF) provided at TU Eindhoven. A number of hypothetical cases are studied, namely fully-printing geometries or combining 3D printing with casting concrete. The final outcome is a 5 m2 partially-printed and partially-cast shell structure, combined with a CNC-milled mould simulating a Flexible Mould.","Adaptable mould; Concrete additive manufacturing; Shell structure","en","journal article","","","","","","","","2020-07-27","Aerospace Engineering","","Design of Constrution","","",""
"uuid:b1a85c4f-cfc9-4253-9bcc-e3f1940dbc5d","http://resolver.tudelft.nl/uuid:b1a85c4f-cfc9-4253-9bcc-e3f1940dbc5d","Two-matrix composites: Carbon fiber micropultrusions embedded in flexible epoxy matrices","Callens, S.J.P. (TU Delft Biomaterials & Tissue Biomechanics; TU Delft Aerospace Engineering); Bergsma, O.K. (TU Delft Structural Integrity & Composites)","","2018","Two-matrix composites combine fibers with two distinct matrices. This is achieved by impregnating fiber bundles with a high-stiffness matrix and embedding the cured bundles in a flexible matrix. Two-matrix composites have been shown to offer unprecedented combinations of transverse flexibility and longitudinal tensile strength, and could offer improved fiber alignment and manufacturability. Here, we explore this concept further by embedding carbon fiber micropultrusions in flexibilized epoxy matrices and examining the longitudinal compression behavior. Our results on thin-walled rings reveal that the failure mode depends on micropultrusion diameter, with small diameters resulting in micropultrusion kinking and larger diameters in splitting and crushing. Additionally, we find that two-matrix composites can offer higher compression strength than conventional composites with the same flexible matrix, despite a lower fiber volume fraction. The inherent manufacturing advantages and high anisotropy could make two-matrix composites interesting candidates for specific applications, such as morphing wings or additively manufactured composites.","Mechanical testing (D); Filament winding (E); Mechanical properties (B); Transverse cracking (B)","en","journal article","","","","","","","","2020-08-10","Aerospace Engineering","","Biomaterials & Tissue Biomechanics","","",""
"uuid:17b4ed03-8c09-4224-8e73-9b3b464e4dd5","http://resolver.tudelft.nl/uuid:17b4ed03-8c09-4224-8e73-9b3b464e4dd5","Training Pilots for Unexpected Events: A Simulator Study on the Advantage of Unpredictable and Variable Scenarios","Landman, H.M. (TU Delft Control & Simulation; TNO); van Oorschot, P. (TU Delft Aerospace Engineering); van Paassen, M.M. (TU Delft Control & Simulation); Groen, Eric L.; Bronkhorst, Adelbert W. (TNO); Mulder, Max (TU Delft Control & Operations; TU Delft Control & Simulation)","","2018","Objective: This study tested whether simulator-based training of pilot responses to unexpected or novel events can be improved by including unpredictability and variability in training scenarios. Background: Current regulations allow for highly predictable and invariable training, which may not be sufficient to prepare pilots for unexpected or novel situations in-flight. Training for surprise will become mandatory in the near future. Method: Using an aircraft model largely unfamiliar to the participants, one group of 10 pilots (the unpredictable and variable [U/V] group) practiced responses to controllability issues in a relatively U/V manner. A control group of another 10 pilots practiced the same failures in a highly predictable and invariable manner. After the practice, performance of all pilots was tested in a surprise scenario, in which the pilots had to apply the learned knowledge. To control for surprise habituation and familiarization with the controls, two control tests were included. Results: Whereas the U/V group required more time than the control group to identify failures during the practice, the results indicated superior understanding and performance in the U/V group as compared to the control group in the surprise test. There were no significant differences between the groups in surprise or performance in the control tests. Conclusion: Given the results, we conclude that organizing pilot training in a more U/V way improves transfer of training to unexpected situations in-flight. Application: The outcomes suggest that the inclusion of U/V simulator training scenarios is important when training pilots for unexpected situations.","flight simulation; mental models; startle; surprise; training","en","journal article","","","","","","","","","Aerospace Engineering","Control & Operations","Control & Simulation","","",""
"uuid:0fab3987-60fa-4737-8e85-b955f5f02d0c","http://resolver.tudelft.nl/uuid:0fab3987-60fa-4737-8e85-b955f5f02d0c","One-second coherence for a single electron spin coupled to a multi-qubit nuclear-spin environment","Abobeih, M.H.M.A. (TU Delft QID/Taminiau Lab; TU Delft QuTech Advanced Research Centre; Kavli institute of nanoscience Delft); Cramer, J. (TU Delft ALG/General; TU Delft QID/Hanson Lab; TU Delft QuTech Advanced Research Centre; Kavli institute of nanoscience Delft); Bakker, M.V. (TU Delft Aerospace Engineering; TU Delft QuTech Advanced Research Centre; Kavli institute of nanoscience Delft); Kalb, N. (TU Delft QID/Hanson Lab; TU Delft QuTech Advanced Research Centre; Kavli institute of nanoscience Delft); Markham, M. (Element Six Innovation); Twitchen, D. J. (Element Six Innovation); Taminiau, T.H. (TU Delft QID/Taminiau Lab; TU Delft QuTech Advanced Research Centre; Kavli institute of nanoscience Delft)","","2018","Single electron spins coupled to multiple nuclear spins provide promising multi-qubit registers for quantum sensing and quantum networks. The obtainable level of control is determined by how well the electron spin can be selectively coupled to, and decoupled from, the surrounding nuclear spins. Here we realize a coherence time exceeding a second for a single nitrogen-vacancy electron spin through decoupling sequences tailored to its microscopic nuclear-spin environment. First, we use the electron spin to probe the environment, which is accurately described by seven individual and six pairs of coupled carbon-13 spins. We develop initialization, control and readout of the carbon-13 pairs in order to directly reveal their atomic structure. We then exploit this knowledge to store quantum states in the electron spin for over a second by carefully avoiding unwanted interactions. These results provide a proof-of-principle for quantum sensing of complex multi-spin systems and an opportunity for multi-qubit quantum registers with long coherence times.","","en","journal article","","","","","","","","","Aerospace Engineering","","QID/Taminiau Lab","","",""
"uuid:43ccb31d-6a6b-4f10-b788-df2c37d84118","http://resolver.tudelft.nl/uuid:43ccb31d-6a6b-4f10-b788-df2c37d84118","Vortex-model-based Multi-objective Optimization of Winglets for Wind Turbines using Machine Learning","Leenders, N.A. (TU Delft Aerospace Engineering; Technical University of Denmark); Yu, W. (TU Delft Wind Energy); Gaunaa, Mac (Technical University of Denmark); Caboni, Marco (TNO); Ferreira, Carlos (TU Delft Wind Energy)","","2022","Different Design Driving Load constraints (DDLs), are explored in this work to determine under which constraints and conditions a winglet can have an added value to the wind turbine blade design. Multi-objective Bayesian optimization is used to maximize the rotor's power production while minimizing the flapwise DDLs. Surrogate models, created using machine learning techniques such as Gaussian Processes and Bayesian Neural Networks, are used in combination with an acquisition function, to determine what designs should be evaluated by the lifting line model AWSM, with the goal to obtain designs that lie on the Pareto front of two or more objectives. The recent Bayesian Neural Networks as surrogate model were able to find the Pareto-front most effectively in this work. Furthermore, the results show that different DDL constraints led to different winglet designs, with noticeable differences between upwind and downwind winglet designs. Winglet designs were found to be able to increase power without increasing the thrust, root flapwise bending moment and flapwise bending moment at radial locations on the blade. A noticeable increase in power was found when introducing sweep to the winglet design.","","en","journal article","","","","","","","","","Aerospace Engineering","","Wind Energy","","",""
"uuid:6d74df0c-f01f-48eb-9005-6139abeada22","http://resolver.tudelft.nl/uuid:6d74df0c-f01f-48eb-9005-6139abeada22","Direct numerical simulation of interaction between a stationary crossflow instability and forward-facing steps","Casacuberta Puig, J. (TU Delft Aerodynamics); Hickel, S. (TU Delft Aerodynamics); Westerbeek, S.H.J. (TU Delft Aerospace Engineering); Kotsonis, M. (TU Delft Aerodynamics)","","2022","The interaction between forward-facing steps of several heights and a pre-existing critical stationary crossflow instability of a swept-wing boundary layer is analysed. Direct numerical simulations (DNS) are performed of the incompressible three-dimensional laminar base flow and the stationary distorted flow that arise from the interaction between an imposed primary stationary crossflow perturbation and the steps. These DNS are complemented with solutions of the linear and the nonlinear parabolised stability equations, used towards identifying the influence of linearity and non-parallelism near the step. A fully stationary solution of the Navier-Stokes equations is enforced numerically, in order to isolate the mechanisms pertaining to the interaction of the stationary disturbance with the step. Results provide insight into the salient modifications of the base laminar boundary layer due to the step, and the response of the incoming crossflow instability to these changes. The fundamental spanwise Fourier mode of the disturbance field gradually lifts up as it approaches the step and passes over it. The flow environment around the step is characterised by a sudden spanwise modulation of the base-flow streamlines. Additional stationary perturbation structures are induced at the step, which manifest in the form of spanwise-aligned velocity streaks near the wall. Shortly downstream of the step, the fundamental component of the crossflow perturbation maintains a rather constant amplification for the smallest steps studied. For the largest step, however, the fundamental crossflow perturbation is stabilised significantly shortly downstream of the largest step. This surprising result is ascribed to a modulation of the kinetic energy transfer between the base flow and the fundamental perturbation field, which is brought forward as a new step interaction mechanism. Possible non-modal growth effects at the step are discussed. Furthermore, the results from DNS indicate significant amplification of the high-order harmonic crossflow components downstream of the step.","boundary layer stability; transition to turbulence","en","journal article","","","","","","","","","Aerospace Engineering","","Aerodynamics","","",""
"uuid:f02782ec-5516-4265-812f-25d4244664ca","http://resolver.tudelft.nl/uuid:f02782ec-5516-4265-812f-25d4244664ca","Experimental investigation of soft kite performance during turning maneuvers","Oehler, J.D. (TU Delft Wind Energy); van Reijen, M.R. (TU Delft Aerospace Engineering; Kitepower); Schmehl, R. (TU Delft Wind Energy)","","2018","Airborne wind energy is an evolving renewable energy technology with the potential to reduce material as well as energy investments and to harvest wind resources that have so far not been accessible. Ground generation systems use the pulling force of a kite to generate a linear traction motion driving a drum connected to a generator. To understand and quantify the aerodynamic performance of a soft kite we developed a sensor system that measures the relative flow conditions on a flying, highly flexible wing. Together with ground-based measurements of traction force, the aerodynamic efficiency of the kite can be computed. The experimental data can be used for the validation of currently available kite models. The lift-to-drag ratio is mainly affected by the power setting or trim of the kite and the steering commands. For the first time the effect of the trim control on the kite's steering capability was quantified for a leading edge inflatable kite. We found that a trim position with higher power ratio which results in a higher angle of attack increases the steering agility of the kite. The attained yaw rate increased by 40%. For optimization of future power kites it is important to understand the mechanisms affecting a kite's performance.","","en","journal article","","","","","","","","","Aerospace Engineering","","Wind Energy","","",""
"uuid:0d6b7cb5-c9c3-4f5c-84c9-38401ad57206","http://resolver.tudelft.nl/uuid:0d6b7cb5-c9c3-4f5c-84c9-38401ad57206","Surrogate based wind farm layout optimization using manifold mapping","Kaja Kamaludeen, Shaafi M. (TU Delft Aerodynamics); van Zuijlen, A.H. (TU Delft Aerodynamics); Bijl, H. (TU Delft Aerospace Engineering)","","2016","High computational cost associated with the high fidelity wake models such as RANS or LES serves as a primary bottleneck to perform a direct high fidelity wind farm layout optimization (WFLO) using accurate CFD based wake models. Therefore, a surrogate based multi-fidelity WFLO methodology (SWFLO) is proposed. The surrogate model is built using an SBO method referred as manifold mapping (MM). As a verification, optimization of spacing between two staggered wind turbines was performed using the proposed surrogate based methodology and the performance was compared with that of direct optimization using high fidelity model. Significant reduction in computational cost was achieved using MM: a maximum computational cost reduction of 65%, while arriving at the same optima as that of direct high fidelity optimization. The similarity between the response of models, the number of mapping points and its position, highly influences the computational efficiency of the proposed method. As a proof of concept, realistic WFLO of a small 7-turbine wind farm is performed using the proposed surrogate based methodology. Two variants of Jensen wake model with different decay coefficients were used as the fine and coarse model. The proposed SWFLO method arrived at the same optima as that of the fine model with very less number of fine model simulations.","","en","journal article","","","","","","","","","Aerospace Engineering","","Aerodynamics","","",""
"uuid:c491ae96-caa3-4602-b7a6-d3e2533ef521","http://resolver.tudelft.nl/uuid:c491ae96-caa3-4602-b7a6-d3e2533ef521","A Bayesian study of uncertainty in ultrasonic flow meters under non-ideal flow conditions","Belligoli, Z. (TU Delft Aerospace Engineering); Dwight, R.P. (TU Delft Aerodynamics); Kok, G. J.P. (VSL Dutch Metrology Institute); Lucas, P. (VSL Dutch Metrology Institute)","","2017","This paper presents an approach for updating the epistemic uncertainty of ultrasonic flow meter measurements under non-ideal flow conditions. Instead of re-calibrating the instrument to correct its behavior in these difficult working conditions, a Bayesian calibration of a computer model of the real process is used. The numerical model is based on computational fluid dynamics (CFD) and a surrogate model is constructed from a limited number of CFD calculations using kriging. The computer model predicts the flow rate dependent on certain parameters including the bulk Reynolds number - which carries information about the true speed of the flow, and is measured only approximately by an ultrasonic flow meter. Bayesian calibration is applied, and the posterior of the true speed can be derived from the marginal posterior of the Reynolds number. This pdf has a smaller uncertainty with respect to the observed data used to fit the model on the condition that sufficiently informative data are available. If this is the case, the proposed approach is capable of reducing not only the uncertainty but also the error associated with the flow meter measurements in non-ideal conditions.","Bayesian calibration; CFD; inverse problems; Kriging; metrology; ultrasonic flow meters; uncertainty quantification","en","journal article","","","","","","","","","Aerospace Engineering","","Aerodynamics","","",""
"uuid:637a0e78-a4fa-4138-8e91-9323439e5776","http://resolver.tudelft.nl/uuid:637a0e78-a4fa-4138-8e91-9323439e5776","Spatial noise correlations beyond nearest neighbors in 28Si/ Si-Ge spin qubits","Rojas-Arias, J. S. (RIKEN Center for Emergent Matter Science (CEMS)); Noiri, A. (RIKEN Center for Emergent Matter Science (CEMS)); Stano, P. (RIKEN Center for Emergent Matter Science (CEMS)); Nakajima, T. (RIKEN Center for Emergent Matter Science (CEMS)); Yoneda, J. (Tokyo Institute of Technology); Takeda, K. (TU Delft Aerospace Engineering; RIKEN Center for Emergent Matter Science (CEMS)); Kobayashi, T. (RIKEN Center for Emergent Matter Science (CEMS)); Sammak, A. (TU Delft BUS/TNO STAFF; TU Delft QuTech Advanced Research Centre); Scappucci, G. (TU Delft QCD/Scappucci Lab; TU Delft QuTech Advanced Research Centre; Kavli institute of nanoscience Delft)","","2023","We detect correlations in qubit-energy fluctuations of non-neighboring qubits defined in isotopically purified Si/Si-Ge quantum dots. At low frequencies (where the noise is strongest), the correlation coefficient reaches 10% for a next-nearest-neighbor qubit-pair separated by 200 nm. Correlations with the charge-sensor signal reach up to 70%, proving that the observed noise is of electrical origin. A simple theoretical model quantitatively reproduces the measurements and predicts a polynomial decay of correlations with interqubit distance. Our results quantify long-range correlations of noise in quantum-dot spin-qubit arrays, essential for their scalability and fault tolerance.","","en","journal article","","","","","","","","","Aerospace Engineering","","BUS/TNO STAFF","","",""
"uuid:4b936c0e-21ac-4922-b4ce-45fa8a0e04ab","http://resolver.tudelft.nl/uuid:4b936c0e-21ac-4922-b4ce-45fa8a0e04ab","Growth, Distribution, and Photosynthesis of Chlamydomonas Reinhardtii in 3D Hydrogels","Oh, J.J. (TU Delft BN/Marie-Eve Aubin-Tam Lab; Kavli institute of nanoscience Delft); Ammu, S.K. (TU Delft Aerospace Engineering); Vriend-Harwig, V.D. (TU Delft BN/Marie-Eve Aubin-Tam Lab; Kavli institute of nanoscience Delft); Kieffer, R.Y. (TU Delft BN/Marie-Eve Aubin-Tam Lab; Kavli institute of nanoscience Delft); Dr. Kleiner, F.K. (TU Delft BN/Marie-Eve Aubin-Tam Lab; Kavli institute of nanoscience Delft); Balasubramanian, S. (TU Delft BN/Marie-Eve Aubin-Tam Lab; TU Delft Industrial Design Engineering; Kavli institute of nanoscience Delft); Karana, E. (TU Delft Emerging Materials); Masania, K. (TU Delft Aerospace Manufacturing Technologies); Aubin-Tam, M.E. (TU Delft BN/Marie-Eve Aubin-Tam Lab; Kavli institute of nanoscience Delft)","","2023","Engineered living materials (ELMs) are a novel class of functional materials that typically feature spatial confinement of living components within an inert polymer matrix to recreate biological functions. Understanding the growth and spatial configuration of cellular populations within a matrix is crucial to predicting and improving their responsive potential and functionality. Here, this work investigates the growth, spatial distribution, and photosynthetic productivity of eukaryotic microalga Chlamydomonas reinhardtii (C. reinhardtii) in three-dimensionally shaped hydrogels in dependence of geometry and size. The embedded C. reinhardtii cells photosynthesize and form confined cell clusters, which grow faster when located close to the ELM periphery due to favorable gas exchange and light conditions. Taking advantage of location-specific growth patterns, this work successfully designs and prints photosynthetic ELMs with increased CO2 capturing rate, featuring high surface to volume ratio. This strategy to control cell growth for higher productivity of ELMs resembles the already established adaptations found in multicellular plant leaves.","3D printing; CO consumption; engineered living material; functional living surface; hydrogel; microalgae; spatial organization","en","journal article","","","","","","","","","Aerospace Engineering","","BN/Marie-Eve Aubin-Tam Lab","","",""
"uuid:f2a23c5b-1afd-4ece-b6ac-1bfcef070970","http://resolver.tudelft.nl/uuid:f2a23c5b-1afd-4ece-b6ac-1bfcef070970","Aeroacoustics of sawtooth trailing-edge serrations under aerodynamic loading","Lima Pereira, L.T. (TU Delft Wind Energy); Ragni, D. (TU Delft Wind Energy); Avallone, F. (TU Delft Wind Energy); Scarano, F. (TU Delft Aerospace Engineering; TU Delft Aerodynamics)","","2022","The impact of aerodynamic loading on a serrated trailing edge is studied experimentally. Aerodynamic and acoustic measurements are conducted on a sawtooth-shaped trailing edge, retrofitted to a flat plate featuring a trailing-edge flap, and placed at incidence to the free-stream flow. The turbulent flow across the trailing edge is inspected by time-resolved three-dimensional velocity field measurements obtained from 4D-PIV, while the wall-pressure fluctuations are measured with surface-embedded microphones. Results discuss the relation between the velocity fluctuations over the serrations, the surface pressure fluctuations, and the far-field noise spectra. The aerodynamic analysis discusses the effect of counter-rotating vortex pairs, generated by the pressure imbalance across the edges of the serrations under loading. It is shown that the interaction of these vortices with the incoming turbulence affects the intensity of the wall-pressure spectrum at the outer rim of the serration surface. On the suction side, the intensity of the pressure fluctuations from the incoming boundary layer dominates over that induced by the vortex pairs. On the pressure side, instead, the velocity gradient prescribed by the vortex pairs produces a significant increase of the pressure fluctuations around the edges. The resulting spatial distribution of the wall-pressure fluctuations directly affects the far-field noise. Scattering predictions carried out with the wall-pressure fluctuations in the centre and root (on the suction side) exhibit good agreement with the measured noise in the low-frequency range, whereas using the surface pressure data at the tip of the serration (on the pressure side) yields a better prediction in the high-frequency range.","aeroacoustics; aerodynamic loading; streamwise vortices; trailing-edge serrations","en","journal article","","","","","","","","","Aerospace Engineering","","Wind Energy","","",""
"uuid:cddccab4-2dd0-4e22-82ae-e37e86978646","http://resolver.tudelft.nl/uuid:cddccab4-2dd0-4e22-82ae-e37e86978646","Performance factors for HAWP systems in pumping operation","Fechner, U.","","2011","","","en","lecture notes","KU Leuven, OPTEC","","","","","","","","Aerospace Engineering","","","","",""
"uuid:841d3ba6-0c9b-40f2-8e01-652d7b8c61d5","http://resolver.tudelft.nl/uuid:841d3ba6-0c9b-40f2-8e01-652d7b8c61d5","Corrosie van vliegtuigconstructies: Deel II: Figuren (Collegedictaat)","de Jong, H.F.","","1986","","","nl","lecture notes","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d691b74d-2283-49bf-960f-2c2b870d58a2","http://resolver.tudelft.nl/uuid:d691b74d-2283-49bf-960f-2c2b870d58a2","Lecture notes on the principles and practice of airplane performance prediction: Part II: Point-performance in steady symmetric and unsymmetric flight","Ruijgrok, G.J.J.","","1983","","","en","lecture notes","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:55f90480-ae7c-4797-bd01-943d5e5e3412","http://resolver.tudelft.nl/uuid:55f90480-ae7c-4797-bd01-943d5e5e3412","Corrosie van vliegtuigconstructies: Deel I: Tekst (Collegedictaat)","de Jong, H.F.","","1986","","","nl","lecture notes","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1945caf8-7702-4cc7-9f8e-71b0bf877dd0","http://resolver.tudelft.nl/uuid:1945caf8-7702-4cc7-9f8e-71b0bf877dd0","Lecture notes on the principles and practice of airplane performance prediction: Part I: Basic elements","Ruijgrok, G.J.J.","","1983","","","en","lecture notes","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a2a1248b-3566-4667-ad8f-70b9b8fad674","http://resolver.tudelft.nl/uuid:a2a1248b-3566-4667-ad8f-70b9b8fad674","Mini ORCHID test rig (poster)","Head, A.J.","","2014","","","en","lecture notes","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:5188e2d1-d1a0-4a70-a700-980c5784a06a","http://resolver.tudelft.nl/uuid:5188e2d1-d1a0-4a70-a700-980c5784a06a","Lecture notes on the principles and practice of airplane performance prediction: Part III: Path-performance in quasi-steady and unsteady symmetric flight","Ruijgrok, G.J.J.","","1983","","","en","lecture notes","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:acfc6d09-7e0b-4682-bdbd-7ef015936064","http://resolver.tudelft.nl/uuid:acfc6d09-7e0b-4682-bdbd-7ef015936064","Lecture notes on airplane stability and control I: Part II","Gerlach, O.H.","","1983","","","en","lecture notes","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d3906029-ebac-4e08-a543-420a837ee1bb","http://resolver.tudelft.nl/uuid:d3906029-ebac-4e08-a543-420a837ee1bb","Lecture notes on airplane stability and control I: Part I","Gerlach, O.H.","","1983","","","en","lecture notes","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:269fa44e-0b09-4fc5-9260-83b6affb7cdd","http://resolver.tudelft.nl/uuid:269fa44e-0b09-4fc5-9260-83b6affb7cdd","Lecture notes on flight-simulation techniques","Baarspul, M.","","1989","","","en","lecture notes","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d03f0a94-5c64-46a0-a0f7-b1ae97db9ecd","http://resolver.tudelft.nl/uuid:d03f0a94-5c64-46a0-a0f7-b1ae97db9ecd","Lecture notes on fatigue, static tensile strength and stress corrosion of aircraft materials and structures: Part I: text","Schijve, J.","","1982","","","en","lecture notes","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7b6dd1e0-1635-449a-ac2e-c2eaa232eb48","http://resolver.tudelft.nl/uuid:7b6dd1e0-1635-449a-ac2e-c2eaa232eb48","The geometric basis of mimetic spectral approximations","Gerritsma, M.I.","Hiemstra, R. (contributor); Kreeft, J.J. (contributor); Palha, A. (contributor); Rebelo, P. (contributor)","2012","","","en","lecture notes","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:accd1f1c-6c92-496a-978c-4b2666b0ac84","http://resolver.tudelft.nl/uuid:accd1f1c-6c92-496a-978c-4b2666b0ac84","Flight path planning in a turbulent wind environment","Fechner, U.","","2015","","","en","lecture notes","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8c8b0678-519d-4480-825d-69d215ae48c3","http://resolver.tudelft.nl/uuid:8c8b0678-519d-4480-825d-69d215ae48c3","Orthogonal Vortex-Propeller Interaction: Vortex Response and Impact on the Propeller Performance","Zhou, T.","Eitelberg, G. (mentor); Yang, Y. (mentor)","2015","In some situations, concentrated vorticity which forms a vortical flow is involved in the inflow of a propeller. The impingement of the vortex on the propeller has several detrimental effects, e.g., foreign object damage during ground operation, impact on the propeller performance, unsteady loading on the blade, and tonal noise generation. The research presented in this report is conducted for the concern of the effects of the interaction between inflow vortex and propeller, in terms of vortex response to the propeller and vortex impact on the aerodynamic performance of the propeller. The impact of impinging vortex on the propeller is studied by experimental and numerical methods. The variation of the propeller performance caused by the impingement of vortex is dependent on the relatively rotational direction of the vortex and the propeller. For the counter-rotating case, the thrust and torque coefficients are increased by the vortex impingement; and vice versa for the co-rotating case. The variations of the thrust and torque coefficients are proportional to the vortex strength. And it becomes more significant as the radial impingement position moves inwards and the advance ratio increases. However, the impingement of vortex does not evidently affects the efficiency of the propeller. The response of vortex to the propeller is investigated by PIV measurement. The variation of vortex behaviors is dependent on the phase angle of the propeller blade. At the phase angles when the wake of the blade is away from the impinging vortex, the vortex core circulation is independent from the impact of propeller. Due to the contraction of the stream tube caused by the propeller suction, the vortex core radius observed in the measurement plane downstream the propeller is smaller than that in the flow field upstream, and the magnitude of vortex vorticity and the maximum tangential velocity becomes larger. At the phase angle when the vortex core coincides with the propeller blade wake vortices, characteristics of the impinging vortex are dependent on the sign of the vorticity of the impinging vortex and the blade wake. For the case that the impinging vortex and the blade wake have the opposite sign of vorticity, the impinging vortex and the blade wake break each other into fractions with smaller core radius and circulation; for the case with the same sign of vorticity, they merge together, forming a new pattern with higher magnitude of vorticity.","vortex; propeller; interaction","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","","",""
"uuid:5492bdad-daca-4f51-97c9-73119ffa0d5a","http://resolver.tudelft.nl/uuid:5492bdad-daca-4f51-97c9-73119ffa0d5a","Rapid Design and Virtual Testing of UAV Within the DEE Framework","Gunaseelan, V.K.","Voskuijl, M. (mentor)","2011","","Electric Powered UAV Design; DEE; Multi Domain Interaction","en","master thesis","","","","","","","","","Aerospace Engineering","SEAD","","","",""
"uuid:5414eab3-9c66-4150-8712-51c3f8e73f16","http://resolver.tudelft.nl/uuid:5414eab3-9c66-4150-8712-51c3f8e73f16","Investigation into reduction of the Cost-Of-Energy of the Upwind 5.0 MW Wind Turbine using Higher- Harmonic Individual Pitch Control","Prinsen, R.C.P.","Bierbooms, W.A.A.M. (mentor)","2011","Individual Pitch Control has been a topic of study in the field of wind turbine engineering for more than a decade. It has been shown that a load reducing controller can be designed that makes use blade root moment measurements. Various authors have performed simulations to estimate the extent to which Individual Pitch Control can reduce fatigue damage for rotating components. More recently, the application of IPC to reduce fatigue damage of fixed frame components has been investigated. One effective method is to extend the IPC algorithm to harmonics of the rotor frequency. While the effectiveness of IPC control is acknowledged by many authors, there has been little published on how to use the fatigue reductions to reduce the cost-of-energy for a wind turbine. In this thesis, an attempt is made to formulate a design methodology for higher harmonic IPC, to capitalize on the fatigue reductions by making design changes to the turbine, and finally estimating the potential profit of these changes. The wind turbine model used in this work is the Upwind 5.0 MW onshore conceptual wind turbine. It was implemented into the aeroelastic wind turbine simulation software FAST. The software of FAST was interfaced with the software package of Simulink which allows for intuitive control design. A combination of Linear Time Invariant control design, and time-marching simulation analyses was used to optimize the various controllers used in the simulations. The reductions of fatigue obtained for the baseline turbine, were around 18% for the blade root flapwise bending moment, and 15% for the analysed moments of the fixed frame components. Based on the fatigue reductions obtained through the controller implementation, three redesign cases were formulated: - Upscaling of the rotor diameter - Reducing the weight of the rotor blades - Increasing the power rating of the turbine Simulations of the redesigned turbines were performed to see if the redesigns were viable. For the cases which were considered viable, the upscaling and weight reduction case, a cost analysis was performed. This cost analysis provided an estimated 1.6 million $ added profit over the turbine lifetime for the rotor upscaling case, and an estimated -130,000 $ loss for the weight reduction case.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","DuWind","","","",""
"uuid:3552d27e-6816-4ea3-85f6-4464deb8f1bd","http://resolver.tudelft.nl/uuid:3552d27e-6816-4ea3-85f6-4464deb8f1bd","Autonomous Collision Avoidance for Swarms of MAVs: Based solely on RSSI measurements","Szabó, T.","Mulder, J.A. (mentor); de Croon, G.C.H.E. (mentor); de Visser, C.C. (mentor); Scheper, K.Y.W. (mentor); Verhoeven, C.J.M. (mentor)","2015","Swarming is a promising solution for extending the flight time and payload carrying capabilities of Micro Aerial Vehicles (MAVs), where recent years have brought many advancements. These allow MAVs to operate ever more autonomously by tackling problems such as obstacle avoidance and autonomous navigation. A major challenge that still remains, however, is to ensure collision avoidance within the swarm itself. Avoiding collisions with other members of the swarm requires knowledge of their relative positions - typically requiring additional sensors to be carried on-board. Using the signal strength of the MAVs’ communication link provides an alternative method for estimating relative distances between the members of the swarm without requiring need for any additional sensors.","","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:59f39b44-b292-4677-bed7-da6b9b310a46","http://resolver.tudelft.nl/uuid:59f39b44-b292-4677-bed7-da6b9b310a46","Improved Prediction of Runway Usage for Noise Forecast","Dhanasekaran, D.","Roling, P.C. (mentor)","2014","The research deals with improved prediction of runway usage for noise forecast. Since the accuracy of the noise forecast depends on the robustness of runway usage prediction, improved accuracy of runway usage prediction will result in improved accuracy of noise load prediction. The main motivation behind this research is that the current method for runway usage prediction does not account for certain factors such as anticipating changes in weather forecast, additional meteorological phenomena, operational disturbances, which influence the controllers in the runway configuration selection decision-making process. The main objectives of the research are to develop runway usage models with increased accuracy of runway usage prediction compared to the current models and to investigate the effect of the developed models on the results of the computations of the noise load around the airport. The novelty of this research comes from improving the accuracy of runway usage prediction and noise forecast and identification of the main factors that influence runway usage. Most of the recent research in this area focuses on runway usage prediction for tactical and strategic planning. There has been very few research carried out on runway usage prediction for noise forecast and this research aims to fill that knowledge gap. Based on literature study, it was identified that modeling with the use of historical data (empirical modeling) can be used to predict runway usage more accurately since it includes the controller’s decision-making patterns. Two prediction algorithms were chosen for the development of runway usage models: Nearest Neighbor and Neural Networks. Two approaches were chosen for runway usage prediction: determination of runway usage directly and determination of runway usage from runway combination prediction. The combination of the prediction algorithms along with approaches was used to develop four runway usage models. The main factors that influence runway usage were identified and used as predictors for the models. The developed models were verified by a comparison with the actual runway usage. Various predictors were analysed to see if it improves the runway usage prediction accuracy. The developed runway usage models were compared with each other in terms of noise forecast accuracy. Based on the effect of the developed runway usage models on the results of the noise load computations around the airport, the runway usage model that resulted in the highest noise forecast accuracy was identified to be the model developed using neural networks that determines runway usage from runway combination prediction. The main factors that influence runway usage were identified to be – wind direction, wind speed, visibility, period of the day, required capacity, type of operation (landing/take-off), and origin/destination. The developed runway usage models were validated for Schiphol airport and can be applied for other complex multi-runway airports like Schiphol airport. This will aid in noise load prediction around the airport for transparency with surrounding communities, determining annual usage plan and analyzing noise mitigation measures.","runway usage prediction; noise forecast; neural networks; nearest neighbour","en","master thesis","","","","","","","","2015-08-29","Aerospace Engineering","Control and Operations","","Air Transport and Operations","","52.0017, 4.3725"
"uuid:8bab122b-b5aa-41c5-b3f4-d23b43da3781","http://resolver.tudelft.nl/uuid:8bab122b-b5aa-41c5-b3f4-d23b43da3781","Design and analysis of the DelFFi solar energy supply","Lopez Telgie, A.I.","Bouwmeester, J. (mentor)","2014","The present thesis deals with the design and analysis of the solar energy supply for the DelFFi nano-satellites. The DelFFi project is parts of the QB50 mission, led by VKI, that intends to launch 50 CubeSat to 350-400[km] altitude in 2016, to carry in situ research in the lower thermosphere. This kind of research has never been done in the past, nor envisioned in the future. Hence, unique challenges are faced by the participating teams. The research was divided into three parts. Part I deals with research a photovoltaic and semiconductors theories, which lead to the understanding of the solar cells working principles. It was followed by an assessment of the available hardware useful for the DelFFi design. Part II deals with Launch and Early Operations of Delfi-n3Xt, predecessor or DelFFi launch on November 21st, 2013, as well as telemetry analysis of the EPS. This lead to lessons learned that could are used in Part III which synthesizes the previous and includes a proposed design of the DelFFi power subsystems. This includes the EPS board and Battery selection, as well as a detailed layout of the solar cells within the panels of the proposed deployment configuration. The later, was used to assess the available power for satellite operations through a model using ESATAN-TMS and Microsoft Excel. Based on the available hardware, and follow up analysis, solar cells assemblies as well as a COTS EPS board and Battery pack have been selected and price quotes are available for procurement. The LEOPS experience as well as the detailed documentation review and analysis, done for Delfi-n3xt, lead to several lessons learned which are employed in the proposed design for DelFFi. The key ones are not relying on the ADCS for the power performance, which lead to a satellite with cell on every face possible as well as double sided deployable panels; a operational balance of the power budget through duty cycling of the subsystems in different operational modes; and a design which increases the overall EPS efficiency from ~63% on Delfi-n3Xt to ~70% on DelFFi. Over the last months an almost full life cycle in a satellite mission has been experience: design, launch, operations, and selection of components. The proposed design remains to be manufacture once the selected hardware arrives on site, and further testing will improve the accuracy of the model used for assessing the available power. The proposed solar energy supply system is and improvement of the one on its predecessor with increased efficiency and design for a mission in a very particular region of the Atmosphere, which will deliver new science returns.","DelFFi; EPS; DelfiSpace","en","master thesis","","","","","","","","","Aerospace Engineering","Space Systems Engineerong","","","",""
"uuid:56a7c878-9d66-4306-9ad4-ececb4de8394","http://resolver.tudelft.nl/uuid:56a7c878-9d66-4306-9ad4-ececb4de8394","Exploration of the Potential of Civil Unmanned Aerial Vehicles Powered by Micro Gas Turbine Propulsion System","Beuselinck, S.M.L.","Colonna, P. (mentor); Voskuijl, M. (mentor); Visser, W.P.J. (mentor)","2015","Civil Unmanned Aerial Vehicles (UAVs) are outnumbered compared to the military equivalents. They could however be of great value to various organizations, companies and the general public. They currently seem to be on the verge of a breakthrough. An interesting technology that could help increase the flight performance of civil UAVs is the micro gas turbine technology. This is a promising propulsion system that is being developed at the moment. It could become a solid competitor for other propulsion systems used to power UAVs due to the higher power-to-weight ratio, lower complexity, higher energy density potential and power density advantage. This could fuel the continuous expansion of civil UAVs even more. The objective of this Master thesis is to investigate the difference in flight performance between a UAV powered by a reciprocating engine and a micro gas turbine; to explore the potential of a UAV powered by a micro gas turbine based propulsion system. The exploration study first identifies the most promising application. Followed by nominating an existing UAV design as a baseline, based on the closest requirement match with the selected application. The Harfang EADS, powered by a Rotax 914 turbocharged reciprocating engine, acts as the baseline UAV. The flight performance of this UAV is determined by a software package in which point performance is integrated to obtain path performance of a typical mission profile. The aerodynamic model of the baseline UAV is determined using a combination of a vortex lattice method and the thin plate approximation. Weight estimation relationships are used to determine the components weight and the center of gravity location. Fuel flow and thrust data of the reciprocating engine are derived from the operating manual of the Rotax 914 engine, while thrust management tables from another Master thesis are used to model different micro gas turbine sizes (86, 70 and 60 kW), each having a number of technology levels. The influence of some of the assumed parameters is investigated by a sensitivity analysis. Minor modifications to the UAV dimensions resulted in a none notable effect on the mission performance of the baseline UAV. Increasing the critical Reynolds number on the other hand had a significant effect on the drag coefficient, while the influence of the Oswald factor on the drag coefficient gradually increased as function of the angle of attack. Changes to the drag coefficient and user-specified propeller propulsion efficiency of the baseline UAV both had limited effect on the mission performance. Modifications to the specific fuel consumption of the reciprocating engine resulted in a more pronounced effect. The research indicates an increase in mission endurance of 4% for the 60 kW micro gas turbine with the highest technology level compared to the reciprocating engine using the same UAV platform. A take-off weight reduction of 18% can be obtained if the UAV platform is optimized for this micro gas turbine by a redesign process; modifying the wing, fuselage and empennage design. The fuel weight is reduced by 12.5% compared to the reciprocating engine as a result of the increased mission endurance and redesign process. The micro gas turbine can therefore perform the same mission as the reciprocating engine with less fuel. This Master thesis therefore concluded that there is a performance gain possible if a reciprocating engine is replaced by a micro gas turbine. This performance gain could also be transformed into a fuel weight reduction, proving the potential of civil UAVs powered by a micro gas turbine based propulsion system.","aeronautics; UAV; flight performance; micro gas turbine; conceptual design","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Flight Performance and Propulsion","",""
"uuid:5a246c3a-5ebf-4f7b-9646-3db42e1167d2","http://resolver.tudelft.nl/uuid:5a246c3a-5ebf-4f7b-9646-3db42e1167d2","A mimetic spectral element method for the 2D incompressible Navier-Stokes equations","Polman, J.D.","Gerritsma, M.I. (mentor)","2017","","Mimetic; Structure-preserving; Spectral method; Finite element method; Computational fluid dynamics; Differential geometry; Algebraic topology; Exterior calculus; Discrete exterior calculus; Navier-Stokes","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:f0e6cd75-50e8-4066-98c4-199881d2ce1a","http://resolver.tudelft.nl/uuid:f0e6cd75-50e8-4066-98c4-199881d2ce1a","Validation of Oceanic Mass Changes derived from GRACE Gravimetry: A comparison with independent data from Bottom Pressure Recorders in the Southern Ocean","Rietbroek, R.","Ambrosius, B.A.C. (mentor); Wouters, B. (mentor); Schrama, E.J.O. (mentor); LeGrand, P. (mentor)","2007","The satellite mission GRACE (Gravity Recovery and Climate Experiment) provides monthly solutions of the global gravity field of the Earth. Temporal variations in gravity reflect mass redistributions over the Earth. Those mass movements are caused by physical phenomena such as ice sheet dynamics, accumulation of hydrological masses over land, the dynamics in the solid Earth and the dynamics in the atmosphere and ocean. This thesis work focuses on the validation of the oceanic mass variations derived from GRACE. The goal of the project is to compare the oceanic estimates from the space-borne instrument with independent data from pressure recorders (BPRs), deployed on the bottom of the deep ocean in the southern ocean. Although those datasets seem to be of a completely different nature they measure the same quantity. Namely, the variations of mass in the atmosphere and ocean, which in their turn influence the dynamics of the ocean. In this study the GRACE data is compared to the following two quantities: - Local bottom pressure at the BPR stations - Pairwise differences of local bottom pressure (a measure of the oceanic transport) The processing methodology applied to the BPR records is as follows: The raw BPR data is de-tided using a harmonic analysis method. The data is then averaged (over a month) to make them equivalent to the GRACE solutions. GRACE data from three different computing centers1 are compared. The spherical harmonic coefficients are converted to equivalent water height and geostrophic flow, indicators of the variations in the ocean and atmosphere. The solution is filtered to remove correlated errors, after which the de-aliasing models are added back to the solutions. The final solution is obtained by applying a spatial averaging filter. The bottom pressure comparison showed good agreements at locations in the southern Indian ocean, the south Atlantic and the Argentine basin. The best correlations obtained values over 0.8 and typical errors of below 1.5 cm. The analysis showed an apparent connection between phenomena in the Argentine basin and near Crozet. A two monthly mode appeared to be present in both areas. The capabilities of GRACE to detect this mode is marginal and further investigation is required. The comparison for the geostrophic flow (pressure differences) showed a significant agreement in the south Indian ocean, with correlations over 0.7 and errors as low as 7 mm/s. Correlations in other areas were weak or even non existent. We conclude that, for dedicated areas, GRACE shows the ability to measure realistic large scale variations in bottom pressure and geostrophic flow on spatial scales yet barely explored.","grace; gravimetry; ocean bottom pressure; deep ocean currents","en","master thesis","TU Delft, Aerospace Engineering, Astrodynamics and Satellite Systems","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f0b40b7c-ca76-4984-a02a-e03c77a06359","http://resolver.tudelft.nl/uuid:f0b40b7c-ca76-4984-a02a-e03c77a06359","Geodynamic modeling of the ice-ocean system on Enceladus","Hellard, H.","Sohl, F. (mentor); Van der Wal, W. (mentor)","2017","The Saturnian moon Enceladus is one of the most geologically active bodies in the solar system. Ridged terrains dominated by intense tectonism are observed on both hemispheres while plume jets emanating from geological surface cracks are con?ned to the South Polar Terrain, thereby suggesting lateral heterogeneity of the satellite's internal structure. While the latter is not directly accessible, thermodynamic modeling provides important insights on its composition and physical properties. This study aims at building a consistent thermal model of the ice-ocean system to derive the layering of the ice shell and its lateral variations. Comparison with current ice shell thickness estimations and key observables such as mean density, moment of inertia factor or heat flux allows to further constrain the satellite's core density. We start from building internal structural reference models composed of four spherically symmetric homogeneous layers: a core, a salty liquid water layer, a lower warm ductile ice layer and an upper cold brittle ice layer. Since the total ice shell thickness is small compared to the satellite's mean radius (less than 10%), we apply and validate the thin shell approximation. It allows us to further compute a three dimensional thermodynamic model of the ice-ocean system accounting for the dissipation of tidal energy induced by diurnal tides. We show that the higher the core density, the thinner the ice shell to keep the salty ocean density within a realistic range (typically below 1250 kg m-3). We show that tidal dissipation solely occurs within the viscous ductile ice layer, and increases towards the poles. The resulting tidal polar surface heat flow is roughly ?ve times higher compared to the equatorial one. We finally propose a method to derive lateral variations of the brittle-to-ductile boundary that is consistent with the computed temperature distribution. Comparison with output power measurements and current estimations of lateral variations of the ice shell thickness allows us to constrain the core density around 3000 kg m-3, corresponding to a partly de-hydrated core.","Enceladus; Interiors; Planetary thermodynamics; Tides","en","master thesis","","","","","","","","","Aerospace Engineering","Astrodynamics and Space Missions and Planetary Exploration","","","",""
"uuid:44cb036b-51b8-4b1e-ba1e-a7d59936caa1","http://resolver.tudelft.nl/uuid:44cb036b-51b8-4b1e-ba1e-a7d59936caa1","Multi-Stage Formation Flight Planning","Doole, M.M.","Visser, H.G. (mentor)","2016","This thesis investigates the concept of fuel-reduction via formation flight of long-haul commercial aircraft on a network-wide scale, particularly addressing the issue of combinatorial complexity in global formation routing and allocation. A multi-stage formation flight planning (MS-FFLIP) tool is proposed as a computationally tractable approach to formation allocation. Assuming all trailing aircraft receive a 10% reduction in the fuel-burn by flying in formation, the optimal routes including the joining and splitting points are computed in four specific stages along the flight depending on the desired formation size. Within a stage, the interconnected allocation problem takes a set of flights, their possible formation combinations and associated costs and optimally assigns them in a fuel-cost minimising formation fleet. The formation flight routing and the associated fuel burn are enumerated rapidly. This fast computation allows the large-scale allocation problem to be solved via a Mixed Integer Linear Program and optimised through an external optimiser solver. Within the context of this thesis, a stage is defined as a collection of events where all flights merge into formation at optimal joining points, driven by an event-based simulation. The MS-FFLIP tool sequentially creates stages until the largest allowable formation size is created. Additionally, the model is capable of handling large sets of flights and in creating large formations of up to sixteen-aircraft allocated to a formation within a real-time operational time limit. Similar models exist in the current literature, however they are highly prone to combinatorial complexity and as a result, their computation times diverge dramatically with increase in aircraft number and formation size. For this reason, the models were not able to capture the majority of the potential fuel-savings. The MS-FFLIP model was compared against the conventional single-stage centralised formation flight planning approach for which 50 eastbound transatlantic flights were evaluated for optimal routes and assigned to formation fleet of up to four-aircraft per formation. The experiment for the centralised formation flight planning approach showed a 5.72% reduction in fuel-burn against its corresponding solo flights, while requiring 58 CPU minutes of computation time. On the contrary, the MS-FFLIP model performed the same experiment within a time frame of 14 seconds while demonstrating potential fuel savings of 5.66%. Moreover, a case study for 267 transatlantic flights was simulated by the MS-FFLIP tool. The results revealed a 6.88% in potential formation fuel savings against solo flights, with up to sixteen-aircraft allocated to a formation, while performing the computation within 9 CPU minutes. The developed model also showed significant fuel saving potentialcompared to local optimisation-based cooperative planning frameworks.","Formation Flight; Centralised Formation Flight Planning; Flight Operations Optimisation; Airline Fuel Saving Strategy; Combinatorial Complexity; Combinatorial Explosions; NP-hard","en","master thesis","","","","","","","","","Aerospace Engineering","Air Transport and Operations","","","",""
"uuid:b3ec7924-de43-47ac-ad26-90afabbfd5ef","http://resolver.tudelft.nl/uuid:b3ec7924-de43-47ac-ad26-90afabbfd5ef","Printing Piezoelectric Composite Sensors: Through AdditiveManufacturing Technology","Tselikos, G.","Groen, W.A. (mentor)","2016","Additive Manufacturing technology has gained a significant amount of interest in both industry and academia in recent years. Current research, though, is still mainly focused on the printing of structural components. In the future there will be a need for smart materials to come to fully integrated components. These smart materials include sensor materials, actuators and othermultifunctional materials. In this thesis a fully dense, biphasic, lead-free piezoelectric composite sensor of randomly oriented and low volume fraction filler was 3D printed in a reproducible manner. The influence of both nozzle size and temperature settings on producing a fully dense disk sample has been investigated by microstructural analysis on the cross sections of randomly oriented printed piezoelectric composites of multiple compositions. In addition there is a clear link between the printing settings of layer height and the infill density with the dielectric constant of the printed sample disk. Moreover, a proportional relationship between piezoelectric charge constant and poling temperatures was indicated. For the in-situ fabrication of structured piezoelectric composites of 1-3 connectivity, a concept design was proposed and developed. Through both an experimental and theoretical approach, a parametric analysis of all the major settings that influence performance of the in-situ concept design, was conducted. The analysis indicated that the parameters of printing speed, length between the two electrodes and temperature, influence both the exposure time and the viscosity of the composite filament inside the setup and, thus, affecting the degree of particle chain alignment. Based on this analysis, recommendations on the settings variation, as well as, a possible alterations of the setup’s configuration were proposed.","piezoelectric composite sensor; additive manufacturing; fused deposition modeling; FDM; DEP; structured piezoelectric composites","en","master thesis","","","","","","","","2018-12-20","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:eee70164-4c99-470d-b8ee-5314ffcf63f8","http://resolver.tudelft.nl/uuid:eee70164-4c99-470d-b8ee-5314ffcf63f8","Computational Methods for the Long-Term Propagation of Space Debris Orbits","Hofsteenge, R.","Noomen, R. (mentor)","2013","Space debris poses a significant problem for the space sector. This problem relates to potential collisions of debris objects with active satellites, which in many cases will lead to catastrophic damage. Due to the absence of natural decay mechanisms in the higher regions of space, debris objects in these regions have very long orbital lifetimes. In order to assess the hazards posed to active satellites, it is relevant to be able to predict how the orbits of these debris objects behave on long timescales. A simulation code in C++ has been created for this thesis project, capable of efficient propagation of space debris trajectories over long periods of time (typically a century or more), while taking into account various relevant perturbing forces. The simulation code can be applied to simulate the orbits of debris objects with a wide range of area-to-mass ratios, from intact satellites to tiny flecks of paint. The results produced with the simulation code have been verified to be consistent with results presented in recent research papers on space debris. An extensive performance comparison has been made regarding the efficiency of different computational methods for carrying out accurate, long-term integrations of space debris orbits. Both traditional integration methods and symplectic integration methods were tested, the latter of which are interesting because of their energy conservation properties. All methods were also combined with different formulations of the equations of motion. Of the methods tested, the Dormand-Prince 8(7) integration method combined with Gauss' form of Lagrange's planetary equations in modified equinoctial elements was found to be the most efficient. The performance of the symplectic integration methods was markedly less for this application than for the integration of completely Hamiltonian systems, though it was certainly acceptable. The simulation code was also applied to predict the long-term orbital evolution for debris objects in GEO and GNSS graveyard orbits. While proposed GEO graveyard orbits were found to be safe, graveyard orbits in the GNSS region were found to be susceptible to resonances induced by the luni-solar perturbations, and hence, require a careful selection of the initial orbital parameters. In all cases, debris objects with high area-to-mass ratios were determined to be dangerous to active satellites, regardless of the initial conditions of the graveyard orbit.","space debris; astrodynamics; numerical integration; orbital perturbations","en","master thesis","","","","","","","","","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:5c67462f-d52e-4b61-adfd-b7d949ab5104","http://resolver.tudelft.nl/uuid:5c67462f-d52e-4b61-adfd-b7d949ab5104","The Effect of Shielding Gas Composition on Weld Bead Geometry during Short-circuit GMA Welding of Inconel625 Alloy","Zhao, Y.","van der Zwaag, S. (mentor)","2016","Recently, X65 carbon steel pipes internally clad with a thin Inconel625 alloy lining are highly used. However, during welding the Inconel625 lining in the root pass, the weld bead is uneven. To avoid weld defects in the successive passes, an additional grinding procedure is always required to flatten the weld bead. It is known that as an indispensable component in GMAW, the shielding gas can protect the liquid metal from oxidation and defects in the atmosphere. The shielding gas composition greatly determines the characteristics of the welding arc which plays a significant role in the heat, mass transfer during welding and flow motion in the weld pool. It is proposed that the uneven weld bead can possibly be improved by changing the shielding gas composition during welding the Inconel625 lining. Therefore, it is necessary to study the effect of shielding gas composition on the weld bead geometry during short-circuit gas metal arc welding (GMAW) of Inconel625 alloy. In this research, short-circuit GMAW of the Inconel625 lining was reproduced in a laboratory scale. Three kinds of gas, argon (Ar), helium (He) and carbon dioxide (CO2) were considered and two types of experimental configurations, bead-on-plate welding and U-shaped groove butt welding were performed. It was found that the shielding gas composition could make a great influence on the arc voltage, power of the heat source (welding arc), flow motion in the weld pool and the resultant geometry of the weld bead. For the Ar-He shielding gas mixtures, the arc voltage is increased as the He content is increased, which is attributed that the ionisation potential of He is higher than that of Ar. As a consequence, with an increase of the He content, the heat source (the welding arc) becomes more powerful and more heat is transferred to the workpiece. A larger fusion area is created. For the Ar-CO2 shielding gas mixtures, it was found that adding 3.3% CO2 to Ar could raise the arc voltage and lead to a more powerful welding arc. More importantly, the presence of oxygen which is dissociated from CO2 can largely reduce the surface tension of the liquid metal. The temperature gradient of the surface tension can be changed from negative to positive and the direction of the Marangoni convection which is driven by the surface tension force will be changed from outward and upward to inward and downward. The efficiency of the heat transfer from the surface of the weld pool to the bottom is greatly enhanced. Consequently, addition of 3.3% CO2 to Ar can deepen the penetration and enlarge the fusion area.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:fae4da57-2237-4b85-8012-0c403cd9a558","http://resolver.tudelft.nl/uuid:fae4da57-2237-4b85-8012-0c403cd9a558","A comparative analysis of project management and systems engineering techniques in Cubesat projects","Elstak, J.","Hamann, R.J. (mentor)","2007","Since the start of CubeSat development different universities and organisations have succeeded in launching and operating their own satellites. Each of these institutes has their own ways in which these projects are organised.Furthermore each project has its own design philosophy and heritage that influence the project. What all these projects do share is a common set of standard CubeSat requirements and similar handbooks on Project Management and Systems Engineering (PMSE). Furthermore the general development time and workforce behind the project are also similar for all institutes. With this in mind it is interesting to investigate where the resulting projects and CubeSats differ and learning opportunities arrise.","project management; systems engineering; cubesat; student satellite; university satellite","en","master thesis","TU Delft, Aerospace Engineering, Systems Integration/Space","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2e9d7ff3-6b5d-4155-8245-d6137682e0d3","http://resolver.tudelft.nl/uuid:2e9d7ff3-6b5d-4155-8245-d6137682e0d3","CoBaPreM Component-Based Predictive Maintenance to reduce unscheduled occurrences: A new strategy to improve reliability practices","De Boer, L.W.M.","Verhagen, W.J.C. (mentor)","2016","Costs associated to unscheduled and excessively prudent maintenance can contribute significantly to an airline's expenditure. Due to the complex nature of aviation related operations, reliability practices have been limited. In an attempt to improve component reliability, i.e. reduce maintenance-related costs, a new strategy was proposed which pursuits new avenues w.r.t. reliability modelling. The strategy focusses on identifying operational factors affecting component reliability and assessing whether these can be used to reduce the number of unscheduled occurrences (i.e. failures). Currently, reliability models are limited to exponential distributions, which assume hazard rates remain constant throughout the component's operational life. Studies have shown that time-independent Proportional Hazard Models (PHMs) could improve overall reliability, however, due to poor data, this was not verified. In this solution, the benefits of both time-independent and -dependent PHMs are assessed. Furthermore, underlying hazard functions were supplemented by introducing: normal, log-normal, logistic, exponential, Weibull, and gamma distributions. To address repairables, restoration events were simulated using Kijima type II General Repair Processes (GRPs). This project would not have been possible without the cooperation of QantasLink that supplied the data required. Results obtained from analysing historical data of the top ten components w.r.t. unscheduled removals indicated that adopting new maintenance schedules, derived from the proposed reliability models, could reduce the number of unscheduled occurrences by approximately 37% while limiting the increase in Mean Time Till (next) Repair (MTTRep). The variables identified by the solution were validated using literature, however, due to variable reduction and data limitations, the exact nature of component failures is yet to be established. Undeniably the potential benefits of adopting the proposed strategy are extensive. Nonetheless, numerous assumptions were introduced to overcome challenges imposed by the complex nature of the data. To overcome these challenges, recommendations and suggestions were proposed for the future development of airline reliability practices.","Reliability Modelling; Predictive Maintenance; Airline Operations; Decision Support","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Operations","","Air Transport and Operations","",""
"uuid:56f1aef6-f337-4224-a44e-8314e9efbe83","http://resolver.tudelft.nl/uuid:56f1aef6-f337-4224-a44e-8314e9efbe83","Development and validation of a real time pumping kite model","Ruppert, M.B.","Ockels, W.J. (mentor); Schmehl, R. (mentor); Bierbooms, W.A.A.M. (mentor); van der Vlugt, R. (mentor)","2012","A pumping kite system is a new innovative way to generate sustainable energy. A large kite is used to generate a pulling force which is transmitted to the ground by a tether. The tether is reeled off a drum that is connected to a generator. When the tether is completely unwound the kite is controlled in such a way it hovers down like a parachute, with almost no traction force, and the tether is reeled-in. This results in a cycle which produces a net amount of energy. Currently multiple institutes and companies are investigating and developing such pumping kite systems, including the ASSET institute at the TU Delft. A simple, realistic and fast kite model is essential during the development of these systems. Such a model could be used for: estimation of the power production, structural optimization, trajectory optimization and for example autopilot development. This thesis describes the development of a realistic real time capable pumping kite model. Initially a literature study gives an overview of the current models available in literature. It explains the advantages and shortcomings of the different approaches. Main shortcoming of most kite models is their limited validation. As a result their accuracy is unknown. Secondary, the measurement data of a 20kW prototype, which has been developed by the ASSET kite group, is used in an extensive data analysis and system identification. The general dynamics are described and multiple relevant phenomena are found. Especially the rotation of the kite has been studied. An useful relation is found which couples the rotation of the kite to the steer input and the side slip angle (or gravitational vector). This relation originates from a moment study of the kite on a quasi-static basis and corresponds with measurement data. Further the sagging of the tether due to tether drag and pod dynamics has been studied. Relatively small sag angles of 0-150 are found during regular flights and a characteristic pattern indicates that especially the pod dynamics play a role in the flight dynamics. Finally the aerodynamic forces acting on the kite have been studied and coefficients needed for an aerodynamic force model have been fitted to the measurement data. It is concluded, based on the literature study and data analysis, that a semi-rigid body modelling approach is most suited. The semi-rigid body model simulated the kite as a point mass with one additional degree of freedom, namely the rotation of the kite around the tether (yawing of the kite). The pitch angle of the kite, which is adjustable in the real system, is incorporated in the model by a variable constrain instead of an additional degree of freedom. The semi-rigid body kite model proves to be a simple and computer efficient model. The kite model is connected to two different tether models. A single spring-damper tether model which simulates the tether as straight and a discretised point mass model which is able to simulate the dynamics of the tether and pod. The kite model with both tether models have been validated by comparing the models to measurement data. Both models seem to realistically simulate the current kite system. The model with a straight spring damper tether model runs approximately 7x real time1 and correctly simulates all variables except the sag of the tether. The discretised tether model simulates these effect correctly but at the cost of simulation speed. Currently it runs approximately 0.5x real time. The discretised model additionally shows more realistic behaviour during non-normal flight conditions.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:617b757b-b237-4dfc-af6e-6593c633b99a","http://resolver.tudelft.nl/uuid:617b757b-b237-4dfc-af6e-6593c633b99a","Multivariate Spline-Based Adaptive Control for High Performance Aircraft in Atmospheric Turbulence","Mehmood, H.","De Visser, C.C. (mentor)","2017","In existing modular adaptive control approaches, the effects of external disturbances such as atmospheric turbulence are often not considered. In real-life flight applications, stochastic atmospheric disturbances can severely degrade the performance of these approaches, resulting in undesired and unpredictable control behavior. In this thesis, robust adaptation laws are developed within the framework of multivariate-spline-based adaptive control. This new approach, referred to as robust spline-based adaptive nonlinear dynamic inversion (R-SANDI), integrates nonlinear dynamic inversion (NDI) and spline-model-based control allocation with a robust real-time aerodynamic model identification routine. The latter is based on the conditional estimation of the deterministic and the disturbance effect. The developed method is applied to control a F-16 aircraft subject to significant aerodynamic uncertainties and turbulence. Simulation results show that the developed control system outperforms a previously proposed deterministic spline-based adaptive NDI controller, which is shown to become unstable in the presence of turbulence. The new controller is able to adapt to large uncertainties within the onboard aerodynamic model, even in the co-existence of high turbulence levels. This enhances flight performance, safety and survivability and facilitates future real-life flight applications in high performance aircraft.","multivariate splines; modular adaptive control; nonlinear dynamic inversion; spline-based control allocation; real-time model identification","en","master thesis","","","","","","","","2020-06-02","Aerospace Engineering","Control & Simulation","","","",""
"uuid:c4be101e-dd83-4eb8-81e1-abf673636656","http://resolver.tudelft.nl/uuid:c4be101e-dd83-4eb8-81e1-abf673636656","Residual-Based Variational Multiscale Large Eddy Simulation Of Turbulent Channel Flow","Conradi, I.M.","Hulshoff, S.J. (mentor)","2007","Recently, Calo [V.M. Calo, Residual-based multiscale turbulence modeling, PhD thesis, Stanford University, 2004] devised the so-called residual-based variational multiscale (RB-VMS) formulation for large-eddy simulation, that uses both the scale separation and the coupling terms in the variational multiscale equations. Using arguments from traditional stabilized methods, an approximation for the unresolved part of the solution was constructed and substituted into the resolved-scale coupling terms to obtain a closed system of equations. The resulting formulation was implemented within a ?nite-volume method, and showed promising results. In order to understand if the basic RBVMS formulation and Calo’s approximation for the unresolved scales was transferable to other discretization techniques, an incompressible RBVMS method has been implemented. The method gives results which are at least as good as the more conventional large-eddy simulation methods with which it was compared. However, the unresolved-scale approximation, which constitutes a signi?cant part of the computational work, was seen to produce no better results than those obtained with traditional residual scaling. It was concluded that unresolved-scale approximation still has shortcomings, but that the residual-based approach is a promising method for the future.","Multiscale methods; Large eddy simulation; Stabilized finite elements","en","master thesis","","","","","","","","2010-01-17","Aerospace Engineering","Engineering Mechanics","","","",""
"uuid:6fe5df50-ff93-4624-a50c-37fb6331eedf","http://resolver.tudelft.nl/uuid:6fe5df50-ff93-4624-a50c-37fb6331eedf","Tailored SID & Profile Allocation for Amsterdam Airport Schiphol","Ceulemans, B.","Visser, H.G. (mentor); Roling, P.C. (mentor)","2016","Currently, only one Standard Instrument Departure (SID) track and one flight procedure is used per runway departure fix combination. In contrast to tailored arrivals, the potential benefit of tailored departures has been left relatively undiscovered. The research objective is to quantify the potential benefit of tailored SID-s and profile allocation for Amsterdam Airport Schiphol by developing a model that is capable of simulating departure trajectories per runway departure fix and optimize the overall allocation of departing aircraft for noise and fuel consumption. The proposed methodology includes a two-step modelling framework. The two models involve the design of novel tailored departure trajectories using a multi objective genetic algorithm and the computation of optimal flight allocation by means of Mixed Integer Linear Programming (MILP). A case study is presented and serves as proof of concept.","allocation; capacity; trajectory optimization; linear programming; MILP; tailored departures; Schiphol; airport; departures; fuel; noise; optimization; multi objective genetic algorithm","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Transport & Operations","","","",""
"uuid:7f445d54-c758-45a8-b87e-a9c0eec61617","http://resolver.tudelft.nl/uuid:7f445d54-c758-45a8-b87e-a9c0eec61617","Analysis of the Rendezvous Phase of e.deorbit: Guidance, Communication and Illumination","Deloo, J.A.F.","Mooij, E. (mentor)","2015","The aim of this thesis is to investigate a debris-remediation technique where a chaser performs a rendezvous with the debris, establishes a rigid-link connection, and actively de-orbits the debris. Remediation of the space environment becomes an increasing urgency, since the continuously growing space debris population in low-Earth orbit currently poses a serious threat for active satellites. Furthermore, on Earth a threat exists due to uncontrolled re-entry of the debris sooner or later. The thesis addresses various aspects of the rendezvous phase for the debris-remediation technique under consideration. Among others, the aim is to assess passive safety of the required manoeuvres in the rendezvous phase. Also, the thesis explores the possibility of continuous ground communication of the chaser during its final approach with the target. Finally, the thesis studies the illumination conditions. This includes sensor blinding, target face illumination and chaser solar array illumination. ESA's satellite ENVISAT was used as design case. The safety aspects of the rendezvous manoeuvres were assessed by analysing the resulting trajectories after various thruster failures. For the analysis related to communication, the chain of core ESTRACK ground stations (located mainly in Europe) was considered. Furthermore, obstruction of the communication signal by the target was studied. Last, for the illumination conditions, obscuration of the Sun by target was taken into account. In the topic of passive safety, the results indicate that fly-around manoeuvres are preferred in the direction opposite to the natural orbital motion, as these are passively safe. On the other hand, manoeuvres on H-bar and fly-around manoeuvres along the natural orbital motion are found to be passively unsafe. It can be concluded from the communication analysis that the maximum duration of the uninterrupted window amounts up to more than half an hour, using the chain of core ESTRACK ground stations. However, the study on communication blockage shows that frequent communication gaps can occur, with the longest gaps being in the order of one minute in duration. In the field of illumination, it can be concluded that correct target illumination and sensor visibility cannot be guaranteed. Furthermore, the results show that the average solar array area available during final approach varies between 35% and 75%, due to both incorrect pointing by the chaser and obscuration by the target.","e.deorbit; ENVISAT; Clean Space; Orbital Debris; Uncooperative Rendezvous; Debris Remediation; Safety; Communication; Illumination; Active Debris Removal","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","Astrodynamics and Space Missions","",""
"uuid:e72c035a-ae70-4623-9f99-16d1afd67865","http://resolver.tudelft.nl/uuid:e72c035a-ae70-4623-9f99-16d1afd67865","Hybrid Vortex Models in 2D: Arbitrary Moving Bodies","Egilsson, Bjarnthor","van Bussel, G.J.W. (mentor); Simao Ferreira, C.J. (mentor); Palha, Artur (mentor); van Zuijlen, S. (mentor)","2015","","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","Aerospace Engineering","",""
"uuid:919fdb70-55a1-4be9-8795-fb7ef87d3382","http://resolver.tudelft.nl/uuid:919fdb70-55a1-4be9-8795-fb7ef87d3382","Design of a composite guitar","Roest, M.G.","Bergsma, O.K. (mentor)","2016","Today’s acoustic guitars are getting increasingly expensive due to the worsening availability of the highest quality woods. Composites show great promise in replacing wood in acoustic guitars as they are lightweight, are not as sensitive to environmental effects and are much stronger. Current composite guitars however do not sound as good as their wooden counterparts. Therefore this thesis research has been set-up to create a composite material that can match wood acoustically and therefore have all the benefits in terms of environmental sensitivity and strength while not compromising the sound quality of the instrument. A new composite is developed and extensively tested. This composite consists of a carbon fibre reinforced polyurethane foam and has a comparable acoustic response to high quality spruce used for guitar soundboards. With this new composite a complete composite guitar is designed, manufactured and tested. The psychoacoustic analysis performed showed that the new composite guitar is considerably more wood like in its sound compared to current carbon fibre acoustic guitars.","Composite; Guitar; Acoutics; Carbon fibre; Laser Scanning Vibrometry (LSV)","en","master thesis","","","","","","","","","Aerospace Engineering","Aircraft Structures and Materials","","","",""
"uuid:721a3b04-0170-485b-b562-bdd1963065ca","http://resolver.tudelft.nl/uuid:721a3b04-0170-485b-b562-bdd1963065ca","Reciprocity in Wind Farm Development: An Applied and Theoretical Approach","Vermeij, R.","Bierbooms, W.A.A.M. (mentor)","2016","Communication in wind farm development is complex. A relationship between wind farm developers and residents which is based on reciprocity can lead to the trust and commitment necessary to deal with these complexities. The role of reciprocity is researched in a case study and a network model of reciprocity is developed. Implementing the findings of the case study in the model gives insight in the conditions for which communication leads to mutual advantage for wind farm developers and residents.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:80aba35e-cd61-4b74-9271-4d6edfcf500b","http://resolver.tudelft.nl/uuid:80aba35e-cd61-4b74-9271-4d6edfcf500b","Alternative Flight Control in Civil Aviation","Geleyns, D.","Vos, R. (mentor)","2016","This report contains a study about the possible benefits of changing the way large airliners are controlled in flight. The goal is to save fuel by decreasing the structural weight of the aircraft. Over the last decades the conventional primary control surfaces in civil aviation have not deviated from elevators, ailerons/spoilers and rudder. Eliminating one of these by compensating with others could hold revolutionary advantages. The research started out by finding alternative ways to control the aircraft around its different axes. This performance analysis was done with a Boeing 747-200 model in the RECOVER Benchmark tool with slight modifications. It was found that yaw control offered no decent alternatives besides the rudder. Pitch control can surprisingly be done with outboard ailerons, although it barely meets the requirements. This finding is attributed to the large sweep angle of the Boeing 747. Roll control offered the most alternatives due to many redundant control surfaces on the wings. Further analysis of unconventional roll control was split into four cases. The first case, flying without any ailerons, was determined to be unable to meet the legal requirements. However, the second case in which two spoiler surfaces were added to the existing six, was found to be satisfactory in all phases of flight. The efficiency of controlling the aircraft with spoilers instead of ailerons was addressed and a considerable difference was found but in the overall flight, this is not an issue. The third case was more moderate as it only removes the inboard ailerons. This case had no issues to meet requirements. The final case is entirely different: flying without spoilers. All roll requirements were met, but only after the outboard aileron was enlarged to within structural bounds. The larger issue with this case was the lack of airbraking features. The second phase of the project focused on evaluating the snowball effect in aircraft design caused by the small changes in the roll control mechanisms. First the weight of the removed components was estimated through a hydraulics model. This showed results ranging from 7% to 20% in subsystem weight decrease, depending on the case. The next step was to run these updated weights through a preliminary design phase. To facilitate the process the Aircraft Design Initiator was used. Two aircraft were reproduced and modified to assess the impact on different scales as well: the Boeing 747-200 and the Boeing 767-200, which is approximately half the size. It was found that the fuel percentage that could be saved for each case are 0.50%, 0.36%, 0.18% and 0.45% in respective order for the Boeing 747. Interestingly, these percentages are nearly identical to those of the Boeing 767. The impact on the operating empty weights does differ slightly, where the Boeing 747 loses more weight than the 767, percentage-wise. Being that the fuel saving on a standard harmonicmission profile is less than 0.50% for any of the cases of alternative roll control, the results are not revolutionary as they are now. The profitability of switching to these new control methods is debatable.","","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:9364b3e1-01e6-4a70-b7c0-94eb5656d48d","http://resolver.tudelft.nl/uuid:9364b3e1-01e6-4a70-b7c0-94eb5656d48d","Effect of Film Cooling on the Aerodynamic Performance of Turbine Blades","Lanzillotta, F.","Gangoli Rao, A. (mentor); Sciacchitano, A. (mentor)","2016","The world and the energy landscape are changing at a great pace. The population is increasing, generating a higher demand for resources, new markets are emerging and Aviation Regulation is driving requirements for clean power and low emissions. Therefore, gas manufacturers are committed to reduce the specific fuel consumption by increasing the Turbine Inlet Temperature (TIT), which in turn allows to reach a high thermal efficiency. Nevertheless, the turbine blade materials have limitations in the maximum temperature due to failure, durability and structural problems. Film cooling is one of the cooling systems employed to protect the blade metallic surface and allow an operating temperature above the melting point of the materials. Air is extracted from the compressor and injected as a protective film on the blade to defend the exterior from the hot gas mixture. However, blowing air around the blade affects its aerodynamic performances. The objective of the present research is to investigate the influence of film cooling on the aerodynamics losses by testing an airfoil in the M-Tunnel of Delft University of Technology, thanks to pressure measurements and Particle Image Velocimetry (PIV). Experiments are performed on a NACA0012 test model with air injection from four rows of holes located on the suction side at 5%, 10%, 15% and 50% of the chord length from the leading edge. The effect of the blowing ratio on the losses is analysed on a baseline case with a free stream velocity equal to 15 m/s, an angle of attack of zero degrees, and Reynolds Number equal to 1.2 x 10^5. In addition, further experiments are conducted using different configurations of angles of attack, free-stream velocities and sealing some rows of holes. The measured losses include contributions due to flow separations, viscous effects within boundary layers and shear augmentation in wakes. Furthermore, mixing processes in wakes and boundary layers as well as the generation, growth, and mixing of vortices are taken into account. Pressure measurements are used to derive the velocity and loss profiles in the wake at 1.3 chord length distance from the leading edge. The loss profiles are symmetric for the baseline case without blowing, and the maximum losses are positioned exactly behind the trailing edge. The losses introduced by film cooling increase till blowing ratio B=0.48 and the wake is shifted to the suction side. In contrast, losses are diminished from B=0.64 to B=1.91. This trend is observed for all the experimental cases. The low momentum of the coolant at small injection rates creates high shear regions which increase mixing losses due to viscous effects. At high values of blowing ratio, the injected air has a high momentum in the direction of the flow, which fills the low momentum regions in the wake, thereby reducing losses. Mean velocity flow fields around the airfoil are presented, as a result of the PIV analysis. Low velocity areas are visible in the wake at low blowing ratios, whereas large blowing ratios create high velocity regions. Considerations about flow separation are concluded from the velocity flow fields, and the velocity fluctuations are shown as indicators of the level of turbulence. The flow is less prone to separate at high blowing ratio since it is energized and more resistant to the adverse pressure gradient. Nonetheless, large amounts of coolant entail great fluctuations near the cooling holes, which could potentially lead to unsteady loads. Furthermore, a numerical approach of the Poisson equation is implemented to reconstruct the static pressure field from PIV data. Lastly, a good agreement between the results of pressure measurements and PIV is observed thanks to qualitative and quantitative comparisons.","","en","master thesis","","","","","","","","2019-10-28","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Flight Performance and Propulsion","",""
"uuid:ebb54c53-3c79-4e67-9405-7451e2eca850","http://resolver.tudelft.nl/uuid:ebb54c53-3c79-4e67-9405-7451e2eca850","Development of an optimization framework for landing gear design","Van Ginneken, P.","Voskuijl, M. (mentor); Vergouwen, P. (mentor)","2016","An opportunity was identified to improve the traditional landing gear design process. Especially in the conceptual design phase, lots of man-hours are consumed by making the same calculations over and over again, for different concepts. Often, an existing gear is therefore used as initial starting point, to simplify the design process. This results in little technical progress. Additionally, integration between the different disciplines involved is sub-optimal which can lead to inconsistent results. In this thesis, an optimization framework is described that can do the preliminary design of a landing gear fully automated. It ensures that communication between disciplines is respected by adding a top-level optimizer which is in charge of changing the design variables. The realization of this framework greatly reduces the repetitive tasks in the design phase of a landing gear. This makes the design phase less limited to traditional architectures while leaving more time to evaluate non-standard solutions that may be lighter, safer and/or cheaper.","MDO; optimization; landing gear; aerospace engineering; MDF","en","master thesis","","","","","","","","2016-02-10","Aerospace Engineering","Flight Performance and Propulsion","","Flight Performance and Propulsion","",""
"uuid:9e0c7a62-149c-4fab-8d27-afe15c1a8795","http://resolver.tudelft.nl/uuid:9e0c7a62-149c-4fab-8d27-afe15c1a8795","Aero- and Hydrodynamic Performance Analysis of a Speed Kiteboarder: Breaking the World Speed Sailing Record","van der Vlugt, R.","Ockels, W.J. (mentor); Beukers, A. (mentor); Schmehl, R. (mentor); de Wachter, A. (mentor)","2009","Motivation: Speed sailing can be seen as the ultimate challenge for a sailing craft. Kiteboarders have recently shown to be capable of extremely high sailing speeds using a relatively cheap and simple combination of a kite and a board. They proved to be the world’s fastest sailing crafts during a record attempt in October 2008, in September 2009 the record was broken again by a large hydrofoil trimaran. Only little is known about the performance characteristics of a kiteboarder. Research is required to investigate the possibilities to further increase the sailing speed and reach the maximum speed potential of a kiteboarder. Problem statement: This thesis aims to obtain a general understanding of what properties are of importance to obtain a high kiteboarding velocity and to understand how each component contributes to the finally obtained velocity. Approach: A kiteboarder can be seen as a sailing system. It is first explained how to calculate the sailing velocity when wind velocity and both the aerodynamic and hydrodynamic efficiency is known. The kiteboarder is divided into four components; the board, the rider, the lines and the kite. Each component is separately analyzed. The aerodynamic forces on the rider and the lines are estimated using available theory. A special effort is made to investigate the kite’s lift and drag coefficients. A new kite testing method is proposed. The test is based on steering the kite in a horizontal path from one side to the other while constantly monitoring kite velocity, line tension and wind velocity. The hydrodynamic properties of the board are analyzed using available empirical results and by analyzing measured data from a kiteboarding session. Two steady state models are built to combine all the obtained knowledge. In the first model the sailing velocity is one of the input parameters. This model serves to provide an overview of all forces involved in a realistic sailing situation. Variations of wind velocity over height are taken into account. Two cases are described and worked out to obtain an overview of the drag distribution over the kiteboarder. The second model serves to predict the improvement in velocity after improving one of the components and is used to optimize line length and sailing direction. Results: It is found that during record sailing conditions 20 to 21 percent of the total drag is created by the kite, 13 to 18 percent by the rider, 3 to 6 percent by the lines and 56 to 63 percent by the interaction of the board with the water. Research focused on the board could thus lead to a large velocity increment. It is also found that optimizing line length and sailing direction could result in substantial velocity increments.","Kiteboard drag; High altitude wind power; Kiteboarding; Speed Sailing; Kite testing methods","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","","",""
"uuid:e2e5a055-019c-4804-9361-1ebbe0ed9d52","http://resolver.tudelft.nl/uuid:e2e5a055-019c-4804-9361-1ebbe0ed9d52","Numerical Time Integration of Stochastic Differential Equations","Myerscough, K.W.","Gerritsma, M.I. (mentor); Frank, J. (mentor); de Baar, J. (mentor)","2010","Most mathematical models used in science and engineering rely on empirical constants and these are usually assumed to have some deterministic value. In reality however these values are subject to stochastic distribution. Be it due to measurement inaccuracy or be it due to physical variance of the parameter, this distribution is ideally not ignored but considered by the model. Such a model will yield a more complete picture of the physical process, inherently improving it. The same can be said for the initial and boundary conditions of any model.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a597dea2-73fe-4084-8e87-5c0be2c6d1c3","http://resolver.tudelft.nl/uuid:a597dea2-73fe-4084-8e87-5c0be2c6d1c3","Sensitivity of glacial isostatic adjustment induced rotational changes to the ice-load history","Van Dael, N.G.","Vermeersen, L.L.A. (mentor); Schotman, H.H.A (mentor)","2006","","glacial isostatic adjustment; rotational changes","en","master thesis","TU Delft, Aerospace Engineering, Astrodynamics and Satellite Systems","","","","","","","","Aerospace Engineering","","","","",""
"uuid:04e3d6f0-a621-4bee-95ef-2c872628ffb2","http://resolver.tudelft.nl/uuid:04e3d6f0-a621-4bee-95ef-2c872628ffb2","An Investigation on Leakage Behaviour of Seals for Aerospace Applications","Agarwal, A.","Melkert, J. (mentor); Lozano Montoya, F. (mentor); Fernandez Rodriguez, D. (mentor)","2014","This research, performed at Airbus Defence and Space Ground System Test Engineering department in Seville, Spain, is a part of ELDAS (Engineering for Leak Detection in Aircraft Systems) project. It deals with carrying out an investigation on the leak behaviour of the sealing systems used in an aircraft particularly A400M. The sealing integrity of a fuel system is, inarguably, a critical aspect in an aircraft sealing technology. The need for NO fluid leakage and consequently preventing any structural damage to the internal components of an aircraft drives the aircraft designers towards carrying out a detailed research on the sealing systems. The analysis is divided into two parts: firstly, to conduct a structural analysis of the current installation and to computationally study the rubber behaviour; secondly, the characterization of the leakage. This combined analysis is to investigate the current issues associated with the sealing system and propose methods for leak estimation by characterization of leak applicable to the fuel system of an aircraft. Several parameters e.g. fluid properties, material properties, surface roughness, flow conditions to name a few, are thought to be correlated with fluid leakage. This document along with the literature study report will summarize the investigation performed to study the effects of these parameters on the seal leak rate. The structural analysis is performed using Ansys Mechanical Parametric Design Language 14.5 to verify if the current design parameters are well within the prescribed limits. The non-linear behaviour of rubber seal is studied and verified with different available analytical models. A grid independence test is performed via error analysis to further strengthen the simulation obtained results. Various time dependent rubber viscoelastic behaviour are studied to understand the seal deterioration over time. This deterioration in stress within a rubber seal (Fluorosilicone) might increase leakage potential over a period of time. Investigation is also performed to understand the importance of lubrication on sealing performance along with the adverse effects of reusing an o-ring seal multiple times and the associated leak potential. Furthermore, analysis is done for different dimensional cases considering the manufacturing tolerance values. Lastly, the complex extrusion behaviour of the seal at high fluid pressure is studied and simulated to understand the seal failure at high pressure. During the literature review, it is observed that of all the leak estimation models available, no formulation appears to have general validity, so a more general model based on different flow regimes appears to be necessary taking into account the different fluid parameters, leak geometry and operating conditions. The study on the leak behaviour of static seals of an aircraft is performed to establish a correlation between gas and liquid leaks. This study can then be used to facilitate industrial leak testing by providing a correlation between leak rates for liquids and gases which can be used to replace liquid based testing with gas based testing. Obviously, the study can be used for planning further experimentation and validation purpose.","gas leak; rezoning; stress relaxation; o-ring; elastomer; extrusion failure; ansys APDL; nomograph; slip flow; choked flow; compression set; Mullins effect","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:35f5b670-eb0d-4a25-a4ab-ec96841bff23","http://resolver.tudelft.nl/uuid:35f5b670-eb0d-4a25-a4ab-ec96841bff23","Aerodynamic and Structural Analyses of the 5 MW Wind Turbine Using BEM and Lifting Line Theories","Gupta, V.","van Bussel, G.J.W. (mentor); Bierbooms, W.A.A.M. (mentor)","2012","Uncertainty in aerodynamic load prediction is an important parameter driving the price of wind energy and thus the wind turbine community is in need of more sophisticated tools for evaluating aerodynamic blade loading. Blade Element Momentum (BEM) theory is the current standard for estimating the wind forces in load case calculations. The predictive capability of BEM falls short for e.g. yawed flow and dynamic in flow cases and also has shortcomings in its assumptions. A physically more correct approach to model the rotor aerodynamics is presented by a lifting line method with a free vortex wake. This approach includes more physics, however the resulting computations are more time consuming. The thesis is attributed to find significant differences in predic- tion of aerodynamic performance and loads using BEM theory and lifting line theory. For this purpose ECN has modelled a state of art software, ECN AEROMODULE. The software has both BEM and lifting line (AWSM) modules. To underline the differences between BEM and lifting line (AWSM) implementation, two load cases are selected from the IEC standard and two test load cases are formulated. For all the load cases, both aerodynamic and structural analysis is done and the results are validated with FOCUS software results. FOCUS software is well developed software and is being used in wind energy industry for many years, it is based on BEM theory. Frequency analysis of the ART wind turbine is done at rated wind speed during normal operating condition to check whether the natural frequencies of blades and tower coincide with the impor- tant excitation frequencies. Aerodynamic phenomena like dynamic in flow and tower presence are studied for both the theories and the contributions of both phenomena on loading of wind turbine are also discussed.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","Sustainable Energy Technology","",""
"uuid:12d5bae4-b061-4acf-a8a4-3a06cd3ce33f","http://resolver.tudelft.nl/uuid:12d5bae4-b061-4acf-a8a4-3a06cd3ce33f","Human operator identification in the LPV system framework","Duarte, R.F.M.","Pool, D.M. (mentor)","2016","Implementation of predictor-based subspace methodology for human operator identification in the LPV system framework.","","en","master thesis","","","","","","","","2021-08-25","Aerospace Engineering","Control and Operations","","Control and Simulation","",""
"uuid:99a81e51-a16a-4234-9515-c55bdf4e4a42","http://resolver.tudelft.nl/uuid:99a81e51-a16a-4234-9515-c55bdf4e4a42","Multi-aircraft Trajectory Optimization for Continuous Descent Arrivals","Puttabakula, A.","Hartjes, S. (mentor)","2017","IT is a known fact that aircraft noise and fuel emissions are the most constraining factors for the growth of aviation. Continuous Descent Arrivals (CDAs) provide significant reductions in fuel consumption and noise footprint on the ground, by following idle thrust descent and eliminating low altitude leveling off. However, limitations such as unpredictability of the trajectory and separation management for CDAs prevent wide-spread implementation. The thesis focuses on overcoming some of these limitations. Optimal control theory is used to optimize the descent trajectory of the aircraft by using fuel and time as the performance index. The problem is formulated as amulti-phase optimal control and is solved by using a pseudospectral method. The theory is also the backbone of General Pseudospectral OPtimal Control Software (GPOPS). The main focus of the thesis is to enable multi-aircraft trajectory optimization for CDAs and ensure sufficient separation between all aircraft along the entire trajectory by implementing the separation algorithm. The possibility of using both distance based and the time based separation is explored in detail. It is demonstrated using Amsterdam Schiphol (AMS) airport’s real-time inbound flight data that it is feasible to apply the separation algorithm to separate aircraft along the entire lateral path while still being able to performCDAs during the peak and non-peak periods. All the limitations pertaining to the separation algorithmare analyzed and discussed in detail. By addressing some of these shortcomings, the simulation environment can be improved to bring itmore close to a real-time scenario. Although a lot of other factors have to be considered for a practical wide-spread implementation, success of this method will result in the aircraft trajectory being more predictable to the ground controller, effectively addressing one of the major shortcomings of CDAs. On a more important note, the success of this method will also result in reduced noise footprint and fuel consumption by aircraft, benefiting both the environment and airlines.","Optimal control; CDA; distance based separation; time based separation","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:726c4d37-e9c3-48f7-a2c2-55511e52f1c9","http://resolver.tudelft.nl/uuid:726c4d37-e9c3-48f7-a2c2-55511e52f1c9","The Oval Fuselage: A New Structural Design Concept for Blended Wing Body Cabins","Hoogreef, M.F.M.","Vos, R. (mentor); Veldhuis, L.L.M. (mentor); La Rocca, G. (mentor); Geuskens, F.J.J.M.M. (mentor)","2012","Faced with the decreasing fossil fuel reserves and the need to decrease its environmental footprint, the aviation industry is searching for alternative fuels and more fuel efficient engines and aircraft. With the current designs reaching their limits, the industry has turned its attention to the family of all lifting bodies. Particularly blended wing body aircraft have received much interest, a combination of a lifting fuselage and a flying wing. It is commonly believed that this design has a high aerodynamic efficiency and lower structural weight fraction, which both contribute to a higher fuel efficiency. Though the concept has been around since World War II, no flying full-scale aircraft with a pressurized cabin currently exists. Additionally, the pressure cabins have so far been dictated by the aerodynamic design of the centre body. This thesis presents an alternative approach in blended wing body design, which has its roots in the design of conventional aircraft. For current aircraft a method called the `inside-out approach' is used, where the design of the fuselage is dictated by the requirements for the passenger and cargo compartment. Following this approach a blended wing body cabin consisting of four tangentially connected arcs, forming an oval fuselage cross-section with no need for an aerodynamic outer surface is designed. The arcs are supported by vertical and horizontal members, doubling as walls, floors and ceiling for the cabin. The research presented in this thesis describes the geometry determination and weight estimation for this new design, for pressurization, wing bending loads and longitudinal fuselage stresses. The weight estimation method that has been developed determines the thicknesses of the structural members per oval fuselage cross section, described by the four arcs and horizontal and vertical members, for a certain cabin geometry and the aforementioned loads. An imposed airfoil shape over the centre line of the cabin restricts the height of each oval cross-section. By placing these oval cross-sections in sequence, and interpolating between two neighbouring sections, a three-dimensional fuselage can be created that follows the airfoil shape. This airfoil-shaped fuselage is combined with outer wing sections, vertical tail planes, engines and landing gears to generate a complete blended wing body model. This model is analyzed by means of a Matlab optimization tool, which was adapted from a pre-existing blended wing body design tool. In this tool, the developed fuselage weight estimation is combined with a wing-weight estimation and an operative empty weight estimation to calculate the total operative empty weight. Three different conceptual design studies of blended wing body configurations, for 200, 400 and 800 passengers, have been optimized and assessed to investigate the feasibility of the new structural cabin design. These designs have been compared to another blended wing body cabin design and to conventional aircraft. In comparison to other blended wing bodies a lower fuel consumption, lower operative empty weight and longer range were found for the same maximum take-off weight and the same payload. A 400 passenger `oval-fuselage' blended wing body showed the most promising results with a 13% lower empty weight, a 6% better fuel consumption and almost 29% longer range. In comparison to the conventional airliners, this particular blended wing body showed a fuel consumption per transported kilogram that was 10% lower than that of the best performing conventional aircraft, the Boeing 777-200LR.","Blended Wing Body; Aircraft Weight Estimation; Conceptual Design; Fuselage Concept; Aircraft Cabin","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:b2328172-746b-4a0b-9937-f2e70f97c224","http://resolver.tudelft.nl/uuid:b2328172-746b-4a0b-9937-f2e70f97c224","Passive Flow Separation Control for High Lift: An Experimental Investigation on a Novel Vortex Generator","Van Egmond, J.J.","Veldhuis, L.L.M. (mentor)","2015","A current focus in the quest for improvement in fuel efficiency in aircraft design is the simplification of complex high lift systems. A simpler high lift system in combination with flow separation control is potentially able to meet the current high lift performance requirements, while still reducing overall complexity. Passive flow separation control is promising for its inherent simplicity. This is in line with the main goal of simplification of the high lift system. This thesis covers an exploratory and experimental investigation of a novel type of passive vortex generator: the internal vortex generator. Its distinctive feature, an internal structure for the generation of vortices below the surface, is hypothesized to create strong vortices low inside the boundary layer. Due to this increase in effectiveness the internal vortex generator can potentially outperform external vortex generators. As no literature is currently available on this novel concept, different designs are evaluated using numerical analysis. The wedge type internal vortex generator, similar to a backward wedge external vortex generator, is found to produce the most stable and strong vortices, which are inherently close to the surface. Its close resemblance to the well-documented backward wedge external vortex generator allows for a detailed design that is based on a literature study. Moreover, it allows for an interesting reference case to be present during the experiment test. The internal vortex generator is experimentally tested against its geometrically equivalent external vortex generator. Both vortex generator types are equipped on the same single element high lift model and tested in the Low Speed Low Turbulence Wind Tunnel at the Delft University of Technology. Force measurements indicate a more than 3% increase in maximum lift compared to baseline, while the geometrically equivalent external vortex increases the maximum lift with less than 1%. When the boundary layer is artificially tripped at 0.067 chord length, the internal vortex generator increases maximum lift with 33% compared to baseline, while the external vortex generator increases the lift coefficient with 16%. Due to practical limitations the force measurements do not accurately represent a real-world condition. Critical analysis, strengthened by oil visualizations and XFOIL simulations, suggest that the wedge-type internal vortex generator is capable of achieving more lift than the force measurements indicate. Moreover, the internal vortex generator concept is found to inhibit unique qualities that can be exploited in future research. Overall, the internal vortex generator concept shows to be a viable improvement to regular vortex generators. Therefore, future research is highly encouraged.","vortex generators; high lift system; passive flow control","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:739bb254-4ece-4125-a304-aa84699f50e4","http://resolver.tudelft.nl/uuid:739bb254-4ece-4125-a304-aa84699f50e4","A particle system approach for modelling flexible wings with inflatable support structures: Incorporating accurate bending deformation of inflatable beams","van der Knaap, E.F.","van Bussel, G.J.W. (mentor); Schmehl, R. (mentor)","2013","Models of kites with inflatable support structures that are both fast and accurate can accelerate the development of airborne wind energy systems. The fast particle system approach has not yet been used to model inflatable beam structures. The goal of this research is to investigate if the bending behaviour of inflatable beams can be modelled accurately by a particle system approach and how such a model affects the computational costs. The inflatable tubular beam is segmented into a number of discrete elements which are connected by rotational joints which include rotary springs. A cluster of 6 particles interconnected with 13 spring forces in the shape of a pyramid was introduced to approximate each discrete beam segment. The reaction moments in the rotary springs were translated to reaction forces on the particles of two connecting pyramids. The simulation was programmed in a Java based particle system environment which uses the implicit Euler integration method for its stability properties. The required Jacobians of the proposed rotary spring reaction forces were derived analytically. The bending behaviour was defined accurate when the tip-deflection deviated less than 1mm with respect to a reference value. A clamped beam with linear stiffness was modelled and compared to Bernoulli bending theory. An inflatable beam with non-linear bending stiffness was then built and compared to a function that was fitted through experimental data of inflatable beams subjected to a tip-force. Accurate bending behaviour was achieved for both test-cases. The computation costs were measured by counting floating point operations in one iteration of a simulation. A sensitivity analysis was performed on the floating point operations induced by adding normal springs, rotary springs, particles, pyramid elements and iterations in the solver. It was found that the rotary springs are roughly 30 times more expensive to compute than normal spring forces. The real-time computation limit was tested by adding multiple beams to the simulation environment. The model proved computationally heavy as the computation time was bounded by the floating point performance of the hardware. Equations describing the computational costs in the particle system could roughly predict the computation time. A simulation of 17 beams comprised of approximately 350 particles, 50 rotary springs and 900 normal springs can run real-time on 2.4 Ghz computer using Java.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","","",""
"uuid:4bef5dc5-d6ef-4e4e-99db-90b7e44624f3","http://resolver.tudelft.nl/uuid:4bef5dc5-d6ef-4e4e-99db-90b7e44624f3","Laser-Based Control of Rotary-Wing UAVs","Gomes, A.","Cunha, R. (mentor); Guerreiro, B. (mentor)","2015","Unmanned Aerial Vehicles (UAVs) present a high technological development rate nowadays. These vehicles can be used to perform dangerous and costly inspection procedures in structures with difficult access instead of human operators, but they still need a close monitoring. This thesis addresses the problem of using exclusively sensors on board UAVs to derive attitude determination tools and trajectory tracking strategies. Firstly, this work discusses the perception of the outside world by the vehicle and the formulation of a mathematical description containing information regarding its position and attitude relative to the structure. For this purpose, a geometry is set and the best fit to the data provided by a LiDAR sensor is selected, after a robust outlier filtering process. With this information, several methods for obtaining the attitude are proposed. These include a fast and comprehensive yaw estimator, based on continuity, and a closed-form solution for the Wahba's problem and a nonlinear filter for a full attitude estimation, both on the group of rotation matrices. A significant effort was devoted to the analysis of the entire procedure through simulation, from the creation of the LiDAR data to the application of the methods, for validation purposes. Both simulated and experimental results are provided for the performance evaluation of the perception algorithms. Building on these results, a nonlinear control strategy is designed with the objective of providing an accurate trajectory tracking control relative to the structure, with guaranteed asymptotic stability.","UAVs; LiDAR sensor; geometry fitting; attitude determination; Lyapunov stability; trajectory tracking","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Operations","","Control and Simulation","",""
"uuid:fbf09f2b-fef3-4dec-bf93-8a9e7101aaf5","http://resolver.tudelft.nl/uuid:fbf09f2b-fef3-4dec-bf93-8a9e7101aaf5","Liquid Jet Gas Ejector Technology for Flare Gas Compression","Follender-Grossfeld, T.R.J.W.","Pini, M. (mentor)","2017","Flare-gas is rest gas from exploration and refining operations. Flare-gas at refineries is a mixture of several production processes’ rest gas. Usually these rest gasses are flared to the atmosphere or re-used as fuel gas after compressing and cleaning it. At Shell Pernis Refinery currently Liquid Ring Compressors are used to compress flare-gas. This technique however has not been designed for processes with varying fluid composition, resulting in significant downtime leading to increased flaring. This thesis research aims to provide Shell with recommendations whether to apply another technique for compressing flare-gas: Liquid Jet Gas Ejector technology. Several alternative techniques for compressing flare-gas are investigated. From this investigation the Liquid Jet Gas Ejector is found to be the best alternative to the Liquid Ring Compressors. The Liquid Jet Gas Ejector is assessed technically and economically. With respect to the technical aspects, the physical principals and flow conditions are researched. A one-dimensional thermodynamic model is written to assess the ejector performance and create an optimized design for various applications. The model is validated against a state-of-the-art Liquid Jet Gas Ejector. In the economical analysis the Liquid Jet Gas Ejector is compared to the Liquid Ring Compressor for two cases on Shell Pernis. The first case investigates whether the Liquid Ring Compressors at a flare-gas recovery unit can be replaced by Liquid Jet Gas Ejectors applying various Shell tests. The second case compares the Liquid Ring Compressor and the Liquid Jet Gas Ejector for a greenfield opportunity for flare-gas compression on Pernis resulting in significantly reduced flaring. This thesis research project has proofed that there is a technical and economical case for applying Liquid Jet Gas Ejector technology for flare-gas compression.","","en","master thesis","","","","","","","","2027-05-09","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:4249a548-5b4e-455e-932b-5e28ed650280","http://resolver.tudelft.nl/uuid:4249a548-5b4e-455e-932b-5e28ed650280","Airfoil Optimization for vertical axis wind turbines","Kemp, R.","Simao Ferreira, C.J. (mentor)","2015","This thesis addresses the process of airfoil optimization for vertical axis wind turbines (VAWT). The airfoils are designed for large scale turbines above 5 MW. The VAWT concept is relevant for offshore floating wind energy, because of its low center of gravity (stability) and their simplicity (low maintenance). An optimal tip speed ratio of 4-4.5 is chosen with an average Reynolds number of 5 million. The solidity c/R of the turbine is 0.1. These operation conditions are representative for the new generation VAWT. The goal of this thesis is to develop an optimization process for VAWT airfoils and to demonstrate it by designing an airfoil, while taking into account airfoil soiling. A literature review presents the previous research in VAWT airfoil design, showing that no consensus has been previously reached about VAWT airfoil design. From the literature review an optimization objective derived by Simão Ferreira [30] is chosen. The airfoil is optimized for aerodynamic and structural performance. The aerodynamics is assessed on airfoil level according to the objective of lift slope over drag. Structurally, the airfoil will be optimized for flapwise bending stiffness. Airfoil soiling is simulated on the airfoil by using turbulent transition. A genetic optimization tool for airfoils coupled with RFOIL, an airfoil analysis tool, is used to generate VAWT airfoils. The objective function values are calculated using the aerodynamic coefficients from RFOIL and the geometric properties of the airfoils. The optimization process is validated by analyzing the results with three different models for full VAWT analysis. These models are: 1) an inviscid panel model coupled with RFOIL, 2) a double wake panel model and 3) a CFD model. Three airfoils resulting from the optimization are tested using the aerodynamic models. The performance of the airfoils validates the objective functions, but performance for the soiled case is not satisfactory. These preliminary findings were presented at the 33rd Wind Energy Symposiumat the AIAA SciTech conference [32], the full paper can be found in appendix B Five different strategies are developed to optimize airfoils. The results are analyzed using a double wake panel model. The optimization strategy in which airfoils are optimized for soiled conditions results in the best performing airfoils. The RK2-27 is a demonstration airfoil resulting from this optimization strategy. The CP of this airfoil for a tip speed ratio of 4 and a solidity of 0.1 is 0.53 in the clean case and 0.45 in the soiled case. This was determined by both the inviscid panel model and the double wake panel model. The RK2-27 has an increased CP compared to the NACA 0018 of 0.04 in the clean case at the design operating conditions. The CP in the soiled case is only 0.02 lower than the NACA 0018. The maximum thickness of the airfoil increased by 50% from 18% to 27%. The RK2-27 has similar aerodynamic performance compared to the traditionally used NACA 0018, while structurally it performs significantly better.","Windenergy; vertical axis wind turbine","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","","",""
"uuid:13dab427-a77c-476b-a352-f1cb7cf6a0e1","http://resolver.tudelft.nl/uuid:13dab427-a77c-476b-a352-f1cb7cf6a0e1","Optimization strategy for conceptual airplane design","Vasseur, P.T.","Vos, R. (mentor)","2014","Due to the ever growing demand for more efficient aircraft novel aircraft concepts have to be explored. By improving design tools the potential of unconventional configurations can be further studied. This requires improvement of conceptual design tools such that more knowledge can be gathered on alternative solutions as early in the design process as possible. Multidisciplinary design optimization (MDO) can support this process by providing an environment in which the various disciplines can be designed and optimized concurrently, while a certain level of consistency is maintained. An optimization design tool has been created to assess the potential performance gains of novel aircraft configurations. It connects with the Initiator design tool, which is a conceptual design framework. As such, it can also be used as a means to expose any design issues that may exist in the Initiator. With the optimizer tool the following four case studies were performed: a conventional Airbus A320, a forward-swept canard aircraft, a threesurface aircraft and an oval-fuselage aircraft. For this purpose the genetic algorithm, a gradient algorithm and a hybrid genetic algorithm were used. From the case studies followed that large improvements can be obtained with unconventional aircraft configurations when compared to the initial aircraft design proposed by the Initiator design tool. Up to 20% improvement was found with the three-surface and canard aircraft. The oval-fuselage aircraft could be improved by a solid 10%, while a 5% improvement was obtained with the conventional A320. Among all cases the most contributing factors were the wing position, sweep angle and aspect ratio. There is a tendency towards lower sweep angles due to the positive effect on the weight of the wing and an underestimation of the drag rise. With the forward-swept canard relatively high sweep angles were found, from which followed that the weight penalty of forward swept wings is underestimated. The sizing routine of the control surfaces is found to be inadequate, since the Initiator derives most parameters directly from the wing and does not properly take into account control and stability requirements. Results have shown that this mainly regards the sweep and dihedral angle. These sizing issues also affect the static margin. It was found that class II design information was not fed back to the control surface sizing. From the used optimization algorithms can be concluded that the gradient algorithm was the least effective as it had difficulties with the noise. It sometimes stopped prematurely or started oscillating. The genetic algorithm was found to be the best option due its robustness. It proved to be far less sensitivity to noise. Its computational cost could be significantly reduced by applying parallel optimization and using a caching mechanism. The hybrid algorithm was found to be too computational expensive. The obtained increase in objective value did not outweigh the added cost.","optimization; aircraft design; mdo","en","master thesis","","","","","","","","2014-06-12","Aerospace Engineering","Aerospace Design, Integration & Operations","","Aerospace Structures and Design Methodologies","","52.009507, 4.360515"
"uuid:d7cfbf36-a5ba-4361-bb66-d53ef7344e5e","http://resolver.tudelft.nl/uuid:d7cfbf36-a5ba-4361-bb66-d53ef7344e5e","Three-dimensional flow and load characteristics of flexible revolving wings at low Reynolds number","Van de Meerendonk, R.","Van Oudheusden, B.W. (mentor); Percin, M. (mentor)","2016","Increasing interest in the field of micro air vehicles has stimulated research activities regarding biological flapping-wing flight. An important characteristic of biological flapping-wing flight that is not commonly taken into account in mechanical model simulations is the influence of wing flexibility. This experimental study explores the flow field and fluid-dynamic loads generated by revolving low-aspect-ratio wings with different degree of chordwise flexibility at a Reynolds number of 10,000. The experimental campaign consisted of phase-locked tomographic particle image velocimetry (PIV) measurements complemented with simultaneous force measurements. The three-dimensional velocity fields are captured in three measurement volumes positioned side-by-side along the span of the wing for different phases of the revolving motion, generating a time-resolved volumetric velocity field data set. Subsequently, from the velocity data the pressure fields are reconstructed as well as the loads acting on the wing. In this study the link between the temporal evolution of the vortical structures and the associated pressure forces acting on the wing is investigated in detail.","Flapping wing; Force/Pressure from PIV data; Unsteady aerodynamics; Vortex flows","en","master thesis","","","","","","","","2016-07-01","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:741ac8e3-c4f6-47f8-be74-85bb1fea4cc2","http://resolver.tudelft.nl/uuid:741ac8e3-c4f6-47f8-be74-85bb1fea4cc2","A Semi-Analytical Weight Estimation Method for Oval Fuselages in Novel Aircraft Configurations","Schmidt, R.K.","Vos, R. (mentor)","2013","Research in aircraft design is focusing on novel aircraft configurations in search for a step change in terms of overall transport efficiency. Aircraft design relies heavily on empirical methods, so-called Class 2 methods, to evaluate the performance of a design. Since these methods are based on statistical data their validity is limited when these are used for the design of novel aircraft. There is therefore a strong need for methods that are valid for the conceptual aircraft design of these novel aircraft. The method proposed in this thesis is a semi-analytical method for estimating the weight of a fuselage constructed using the oval fuselage concept. The oval fuselage is a concept for a wide unobstructed pressurized cabin specifically useful for Blended Wing Body aircraft. A parameterization of the oval fuselage is presented and it is demonstrated that the oval cross-section can be used for the design of conventional tube-and-wing aircraft with a single-deck or twin-deck layout as well as for blended-wing-body aircraft. It is also shown that the oval cross-section allows for additional design freedom of the fuselage shape without introducing any bending loads in the fuselage skin panels. Using this parameterization, a method is presented for estimating the weight of this fuselage when used in conventional and novel aircraft configurations. The weight estimation of the fuselage is based on the combination of pressurization loads, steady-state maneuver loads, aerodynamic loads and landing loads. Each of the structural members of the inner structure is sized based on two-dimensional structural analysis satisfying requirements on bi-axial strength, global buckling, crippling, dimpling, and wrinkling. The outer structure is sized using a global buckling criteria adapted from cylinders and a local buckling criteria based on buckling of slender plates. Empirical methods are used to calculate the nonstructural weight and additional weight. A verification of the structural analysis method by a finite-element analysis shows that the made assumptions for the analysis of the structure are valid within the application of aircraft fuselage design. The weight estimation method is compared with weight estimation methods from the open literature and with weight data of existing aircraft. The accuracy of the weight estimation is similar to that of empirical methods for circular fuselages. Examples are shown of oval fuselages in aircraft designs and weight estimations are performed on these fuselages to form a basis for future research on this subject.","class 2.5 weight estimation; oval fuselage; novel aircraft; weight estimation; fuselage; circular fuselage; mdo; first principles; aircraft design; structural analysis","en","master thesis","","","","","","","","2013-11-13","Aerospace Engineering","Aerospace Design, Integration & Operations","","Aerospace Structures and Design Methodologies","",""
"uuid:0fd1d4f7-b3b9-4bbb-b273-25af3f09c616","http://resolver.tudelft.nl/uuid:0fd1d4f7-b3b9-4bbb-b273-25af3f09c616","Towards Understanding Human Adaptation: Time-Varying Parameter Estimation Utilizing the Unscented Kalman Filter","Rojer, J.","Pool, D.M. (mentor)","2017","Human controllers are an essential part of human-machine systems, because of their capability to adapt. However, current manual control cybernetics theory falls short in describing the adapting human controller. In this study the time-invariant human operator models are made parameter varying over time to describe human adaptation. A steady-state Unscented Kalman Filter method is developed to estimate the model parameters without making any \textit{a priori} assumptions on the shape of variation. The method is compared to the current state-of-the-art, which applies maximum likelihood estimation with assumed sigmoid shape parameter variation. A novel metric is introduced, the $J$ metric, which describes the model quality as a function of the local estimation errors. The $J$ metric is used for judgement on the estimation performance in computer simulations, where the exact estimation errors can be computed. Results show that the sigmoid parameter shape variation is reasonable. The model quality lost for the maximum likelihood estimation was below 2\%, even when the sigmoid assumption is violated with perturbations. It also revealed that the steady-state Unscented Kalman filter can retrieve the parameter variation while losing less than 10\% model quality. A human-in-the-loop experiment was conducted which showed the capabilities of both methods to retrieve the adaptation. As expected, the steady-state Unscented Kalman Filter has more difficulty with faster parameter variations, but did not lose any major model quality. This paper demonstrates the successful development of the steady-state Unscented Kalman filter and its capabilities to retrieve human adaptation. Future research can directly implement this method for compensatory tracking tasks.","","en","master thesis","","","","","","","","2022-01-26","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:484e8250-7f38-46de-8b5b-7637c6ab77c9","http://resolver.tudelft.nl/uuid:484e8250-7f38-46de-8b5b-7637c6ab77c9","Guidance and Control for Re-entry Vehicles in the Terminal Area: Application of Pseudospectral Methods","Huneker, L.J.","Mooij, E. (mentor)","2016","One part of spaceflight technology that has always been in demand is to go to space using a vehicle that can be re-used without much additional costs. It is roughly five years ago that the last Space Shuttle mis- sion took place, and replacements are currently in development. Yet, much of the available literature is still based on architectures created during the development of the Space Shuttle. The goal of this thesis is to expand the current knowledge with modern computational methods. This thesis demonstrates if pseudospectral methods can be used as the basis of a guidance and control architecture in the terminal area. In the past, these architectures were based by decoupling the longitu- dinal and lateral dynamics, using the energy available to calculate the current state without knowing what is to come, and calculating many variables and possible scenarios before the flight has even commenced. The architecture presented here does not require this, and it demonstrates an integrated package that can do this on the fly, by deploying a type of non-linear optimization method called pseudospectral methods. The X-38 is chosen as the reference vehicle due to the compatibility of the aerodynamic data set with non- linear optimizers. A 3-DOF simulation is created to see what set of feasible trajectories can be created un- der nominal conditions. Subsequently, a single reference trajectory is used as a basis to determine if the guidance subsystem is able to cope with a wide variety of initial conditions. The guidance system proved to be quite robust. A set of winds and gusts have been simulated and it would return to the desired state as long as there is an approximate predictive ability. The research is later continued by extending to a 6-DOF simulation. A control subsystem based on LQR is implemented with good results. A PSM implementation is introduced after and the results are promising, but the computation time is too high to be feasible. The upside is that a result is found without calculating the deflection of the trimmed state and gains, which was required with LQR. The conclusion is that pseudospectral methods can be used as a robust real-time guidance method, but that using it as a control method is currently not feasible. It is thus proven that pseudospectral method is able to deal without calculating predictive trajectories and gains as was done with the Space Shuttle. This reduces the complexity of re-entry problems by a sub- stantial amount. The time it takes to solve problems with new conditions and spacecraft is reduced, which might encourage other people to continue in this direction. There is still much more possible than what is presented in this thesis.","","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","Space Exploration","",""
"uuid:a8e72529-24f4-4419-b772-d9d300ce1aa8","http://resolver.tudelft.nl/uuid:a8e72529-24f4-4419-b772-d9d300ce1aa8","Development an Verification of the Electro-Optical and Software Modules of the Facet Nano Star Sensor","Fraile Garcia, E.","Kuiper, H.J.M. (mentor)","2014","This Thesis report is written for the space community, specially for people interested in the field of nanosatellites, who know how star trackers work, but are unfamiliar with their operations and limitations in an earth observation mission. To introduce users to the topic, this document is primarily concerned with a single aperture star tracker in order to simplify the explanation. The general mission parameters are described and the critical requirements are flowed down to the Attitude Control System and subsequently the star tracker. Various influences on star tracker performance and availability are described, and different subsystems are analyzed in terms of system performance: optics, baffle, image sensor and on-board software. In addition, the verification process was present from the very beginning, including a verification plan and the calibration and validation activities to be performed on ground in the lab and during the commissioning phase. It is shown that a single aperture star tracker is well suited for a very limited set of operating conditions, namely a strictly nadir-pointing earth observation mission, however the flexibility and robustness of the multiple-aperture star tracker is generally required for missions with realistic operational requirements.","star tracker; verification; space systems engineering; CMOS sensor; centroiding; star detection; star sensor","en","master thesis","","","","","","","","2015-09-25","Aerospace Engineering","Space Systems Engineering","","","",""
"uuid:3aff1b36-0d2f-48ba-8d7c-950c75daaf52","http://resolver.tudelft.nl/uuid:3aff1b36-0d2f-48ba-8d7c-950c75daaf52","Effects of Micro-Ramps on a Shock Wave/Turbulent Boundary Layer Interaction","Blinde, P.L.","Scarano, F. (mentor); van Oudheusden, B.W. (mentor); Humble, R.A. (mentor); Souverein, L.J. (mentor)","2008","Shock wave/turbulent boundary layer interactions (SWTBLIs) are a class of fluid dynamic phenomena that are prevalent in many applications, e.g. helicopter blades, supersonic inlets, missile and aircraft after bodies, etc. The interactions are an important source of drag and can cause turbulent and unsteady separation of the boundary layer, leading to increased heat fluxes and fluctuating pressure loads, which can be severe enough to cause structural damage and premature fatigue of aero-structures. By placing vortex generators (VGs) upstream of a SWTBLI, the detrimental effects of the shock induced separation can be diminished. One particular type of VG is the micro-ramp. Because of their wedge-like shape, micro-ramps are very robust and easy to apply compared to most other VGs. Recently, studies that made use of velocity data in wall-parallel planes have led to renewed insight in the role of variations in the incoming boundary layer on the interaction’s phenomenology. For this reason, stereo-particle image velocimetry (stereo-PIV) measurements in two wall-parallel planes have been performed to investigate the effect of two configurations of micro-ramps, a single row and a staggered array, on an oblique shock reflection on a flat plate at a freestream Mach number of 1.84. The micro-ramps had a height of 20% of the unperturbed boundary layer thickness and the measurement planes were located 0.1 and 0.6 boundary layer thicknesses away from the wall. Additionally, oil-flow patterns at the surface were obtained. The micro-ramps were observed to generate individual vortex pair packets downstream of their vertices that on the mean look like longitudinal streamwise vortex pairs. These structures perturb the incoming boundary layer in such a way, that on the mean low-speed regions exist downstream of the vertices and high-speed regions at intermediate locations. Downstream of low-speed regions in the incoming boundary layer the probability of reversed flow occurrence in the interaction region was found to be higher and the subsonic region to be longer in streamwise direction. These and other results have been used to construct a tentative conceptual model of the effect of micro-ramps on the boundary layer’s and interaction’s topology. Overall, the probability of the occurrence of reversed flow in the interaction region decreased by 20% and 30% downstream of the single row and the staggered configuration respectively. Both configurations of micro-ramps were found to stabilize the shock motion by reducing the length of its motion by about 20% in the lower measurement plane. Farther away from the wall only the single row configuration was found to be effective, leading to a spanwise averaged reduction of 30% in the upper measurement plane. Because of all these benefits, it is recommended to further develop micro-ramp control, whereby the conceptual flow model proposed in the present investigation can provide (part of) an initial framework in which this can be done.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:a4dd8c82-0c46-4c1f-847b-7fd5d9b638be","http://resolver.tudelft.nl/uuid:a4dd8c82-0c46-4c1f-847b-7fd5d9b638be","Goal-oriented a-posteriori error estimation and adaptivity for fluid-structure interaction: Application to a prototypical 2-D model problem","Fick, P.W.","Gutiérrez, M.A. (mentor); Brummelen, E.H. (mentor)","2008","In this thesis, we apply the existing framework for duality-based a posteriori error estimation and goaloriented adaptivity to a prototypical fluid-structure-interaction model problem. Specifically, we consider the two-dimensional panel problem concerning the aeroelastic response of a flexible panel with infinite aspect ratio immersed in an inviscid fluid flow. For general linear and nonlinear output quantities of interest, we formulate an appropriate dual problem and derive dual-weighted Type I a posteriori error estimates. The sharpness of these estimates is demonstrated through a series of numerical experiments for physically stable as well as physically unstable test conditions in both the subsonic and supersonic regime. On the basis of the derived a posteriori error estimates, we then design and implement an adaptive algorithm capable of producing space-time meshes specifically tailored to the efficient computation of a certain target quantity of interest. Numerical results are presented, highlighting the superiority of the proposed duality-based approach over a more traditional mesh refinement algorithm employing a residual-based indicator. Furthermore, comparisons between h- and hp-refinement strategies are made to illustrate the extra increase in efficiency, which can be gained from the use of hp-refinement techniques","adaptive finite element methods","en","master thesis","TU Delft, Aerospace Engineering, Engineering Mechanics","","","","","","","","Aerospace Engineering","","","","",""
"uuid:945c1293-c61b-48e0-a40c-7ce20a05d100","http://resolver.tudelft.nl/uuid:945c1293-c61b-48e0-a40c-7ce20a05d100","Efficiency and de-icing capability of nanosecond pulsed dielectric barrier discharge plasma actuators","Van den Broecke, J.","Correale, G. (mentor)","2016","In this work a study was performed on the electrical, fluid-mechanical and net efficiency of nanosecond-pulsed dielectric barrier discharge (ns-DBD) plasma actuators. The plasma actuator efficiency was tested for dielectric barriers with a thickness between 0.5 and 1.5mm and made out of four different materials: Kapton, Lexan, PTFE and silicone rubber. Also, ns-DBD plasma actuators were investigated for their use as de-icing devices. This type of plasma actuator has been studied in research for its flow-control properties, however, this work investigated the same device for its use as a de-icing device. The cold-climate wind energy industry is still looking for a good working and reliable de-icing device. The ns-DBD plasma actuator could serve a double purpose on a wind turbine rotor blade by being both a flow-control device and a de-icing device. Experiments were performed at the Offshore Wind Infrastructure lab (OWI-lab) and confirmed that the ns-DBD plasma actuator can be used for de-icing. Part of the experiments were performed with a ns-DBD plasma actuator having an extended discharge and during the experiments performed in this research discharge lengths of up to 4cm were obtained.","Plasma actuator; ns-DBD; de-icing","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics and Wind Energy","","Aerodynamics","",""
"uuid:ba617923-f403-4d3d-bed9-a333a1021eea","http://resolver.tudelft.nl/uuid:ba617923-f403-4d3d-bed9-a333a1021eea","Optimal Positioning of the Extended Tail pipes for Liquid Removal from Gas Wells","Amusa, S.","Bakker, P.G. (mentor)","2009","","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:560656ea-4e16-4644-b68e-cae11ad30306","http://resolver.tudelft.nl/uuid:560656ea-4e16-4644-b68e-cae11ad30306","Convex Guidance, Navigation, and Control for Pin-Point Lunar Landing","de Ridder, K.M.","de Mooij, E. (mentor)","2016","Convex guidance is a developing guidance algorithm that seeks to unify the trajectory optimisation for pin-point landings. The unification would mean the elimination of the need of different optimisation techniques for different stages of the landing. Using convex optimisation, convex guidance is guaranteed to find the global-optimum of the design space. This study analysis the convex guidance algorithm in depth and establishes the magnitude of the errors introduced by simplifying assumptions. Subsequently, the performance and robustness of convex guidance is investigated in a full guidance, navigation and control loop. It is found that convex guidance can practically be used for a pin-point Lunar landing. However, the combination of a large discretisation step with a zero-order hold function for the optimal control proved to be an ineffcient solution for optimising the spacecraft’s attitude. A linear control function proved to greatly reduce the attitude control effort, and requires far less computational effort than reducing the discretisation step of convex guidance. Therefore, it is recommended to at least use a first-order function for the control vector. Furthermore, because no attitude dynamics are modelled by convex guidance, large attitude discontinuities can occur during the landing, and no initial- or final-boundary attitude conditions can be imposed. Carefully tuned controllers can deal with these discontinuities without upsetting the system, but deviations from the optimal trajectory cannot be avoided. Therefore, a future study is recommended into expanding convex guidance with angular rate limiters to improve the robustness of the algorithm.","Convex Guidance; GNC; Lunar landing; Moon; convex optimisation; convex programming; trajectory optimisation; fuel minimisation; Extended Kalman Filter; Quaternion Control","en","master thesis","","","","","","","","2017-07-01","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:738d8779-57d1-4308-a963-f9925505a8fe","http://resolver.tudelft.nl/uuid:738d8779-57d1-4308-a963-f9925505a8fe","Mimetic Spectral Element Method for Elliptic Problems","Bouman, M.P.","Gerritsma, M.I. (mentor); Bijl, H. (mentor)","2010","Solving Partial Di®erential Equations (PDE's) numerically requires that the PDE or system of PDE's be replaced with a system of algebraic equations. The replacing system of algebraic equation should be mimetic in the sense that discrete operators that make up the PDE mimic the vector identities that connect the continuous operators. The equation that we focus on is the Poisson equation. The Poisson equation can be split up into two ¯rst order equations, where one equation is the divergence relation for some conserved quantity. We then rewrite this system of equations in terms of di®erential geometry. The advantages of using di®erential geometry is twofold. The ¯rst is that there is a very obvious link to its discrete counterpart which is algebraic topology. Second is that the mapping of spaces and the functions de¯ned in these spaces is very well de¯ned. With these properties we are able to derive a compatible (mimetic) discretization for the Poisson equation for arbitrarily shaped curved spectral elements. On these curved elements we are able to retain exponential convergence. In creating a compatible discretization we have to introduce a type of basis function that does not reconstruct the continuous ¯eld from nodal values at collocation points, but rather reconstruct a continuous ¯eld from integrated values. We call these functions, edge functions, because of their connection with edges rather than nodes. Making use of these edge functions the method shows absolute conservation for arbitrary element order and arbitrarily shaped elements. With a minor adaptation we can extend the method to the more general elliptic type problem, especially anisotropic di®usion problems like Darcy °ow. In both of these cases the use of multiple elements follows quite naturally, and also in the multi-element case we retain theoretical convergence rates and absolute conservation.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ec68055b-990a-45b5-af26-9dd67372f6d1","http://resolver.tudelft.nl/uuid:ec68055b-990a-45b5-af26-9dd67372f6d1","LES and Unsteady RANS simulations of Multiple Jet Impingement System","Penumadu, P.S.","Rao, G.A. (mentor)","2015","Jet impingement is a subject of extensive research over the years due to its industrial importance and the fundamental physics of heat transfer and turbulence. These jets generate high heat transfer rates with better uniformity on the surface which is to be heated or cooled compared to other heat transfer techniques. However, to study the flow phenomenon and heat transfer rates, conducting experiments overtime for change in design has become expensive. Hence, to reduce the cost and time, the best possible way to study the jets behavior is to perform numerical simulations. With numerical simulations, one can predict the flow physics inside the domain, which is difficult to obtain from the experiments. In the recent times, there have been tremendous developments in terms of computation power and numerical models that have proved to produce good and accurate results for many applications. With these approaches, the flow characteristics can be studied in depth at each and every time step which provides better understanding about the jets behavior inside the array. However, these new models have to be tested and should be compared with experimental data to see how good these approaches can fit with the experimental results. Moreover, Large-Eddy Simulations (LES) have not been carried out in the past to investigate the flow features in an impinging jet array. So, this master thesis is focused on performing LES and Unsteady Reynolds-averaged Navier-Stokes Simulations (URANS) for multiple impinging jets and validate these CFD results with the experimental data. The primary objective of the thesis is to predict the pressure drop characteristics across the nozzles and the flow channel as the pressure drop directly affects the efficiency of the system. Simulations with Reynolds-averaged Navier-Stokes (RANS) is a good method to analyze these quantities, but it was found that through RANS approach, the results obtained from CFD simulations are over predicted than the experimental values and this deviation increases with increase in Reynolds number. So to analyze these quantities, transient simulations are performed to predict the flow physics and heat transfer characteristics. From the unsteady RANS and large eddy simulations, it was understood that the major pressure loss oc- curs inside the nozzles and due to contraction effect at the nozzle’s inlet. It was also observed that inside the nozzles the pressure drop occurs differently for the particles near the wall and particles which are in the mean flow. The pressure drop values obtained from the CFD simulations are validated with the analytical and experimental results. It was found that, the results are in good agreement with the analytical results. Fur- thermore, the heat transfer characteristics obtained from these transient simulations also show a substantial improvement compared to RANS models. The deviation in the results were found to vary between 7% - 10%. To study the effect of geometrical parameters on the heat transfer and pressure drop characteristics, a sensitivity analysis was performed by varying the nozzle to plate distance and hole diameter. It was noticed that, with the change in nozzle diameter by 10 microns, the total pressure drop of the impingement system is affected significantly. Therefore, when designing these precision systems, it is important to manufacture them accurately as, a minor change in the jet diameter would affect the system performance on a large scale. Finally, It can be concluded that, the unsteady RANS simulations would be a good approach to study the heat transfer characteristics and flow physics inside the array. However, it would be a difficult task for any turbulence model to accurately predict the pressure drop characteristics in the impinging array, as the pressure drop inside the array is extremely sensitive with the change in geometrical parameters.","LES; Jet Impingement; Unsteady RANS; CFD; Multiple jets","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:0361165b-26f0-476c-b48e-74667ebac7a8","http://resolver.tudelft.nl/uuid:0361165b-26f0-476c-b48e-74667ebac7a8","A hybrid method for the interior and exterior design of blended-wing-body cabins","Baan, Y.M.","Vos, R. (mentor)","2015","Considering the fact that all large commercial aircraft have not changed significantly in their tube–and–wing shape during the past few decades, one would suggest that a completely different configuration is necessary to facilitate a new leap forward in aircraft performance. The blended–wing–body is potentially such an alternative configuration. Existing conceptual design methodologies do not always apply to these configurations since they are often based on empirical relations for, or intensively tailored towards, tube–and–wing configurations. Developing new conceptual design methodologies for the interior and exterior design and analysis of these blended–wing–body configurations forms the main objective of this study. An automatic, fast–turnaround, non–empirical aircraft cabin sizing method, hereafter called Cabin Configurator, has been developed that places all the required elements within aircraft cabins. The dimensions in which the elements are fitted can be sized automatically by the method itself (inside–out approach) but can also be pre–defined by the designer (outside–in approach). Other key differences with existing design methods are the ability to cope with arbitrary cabin shapes such as the trapezium–like blended–wing–body cabin and to exchange seats for galleys and lavatories. The Cabin Configurator has been extensively validated against a large amount of existing tube–and–wing cabins. The average underestimation of the cabin length and cabin width for widebody configurations is found to be 7.8% and 4.4% respectively. For narrowbody configurations, the overestimation of the cabin length is found to be 5.2% where the cabin width is underestimated by 1.9%. No conclusions could be derived about the feasibility of Cabin Configurator results for blended–wing–body cabins due to the lack of well–documented cabin designs in the research field. A fast–turnaround aerodynamic analysis method, hereafter called BWB–Q3D, has also been developed that analyses the wing and fuselage exterior of a blended–wing–body configuration from an aerodynamic perspective. The three–dimensional lift and drag coefficients are estimated by the combination of a vortex lattice method with a two–dimensional airfoil analysis method. An important consideration in the BWB–Q3D methodology is setting the sectional sweep angles of the fuselage to zero, leading to conservative estimations of the drag coefficients. BWB–Q3D has been validated with high–fidelity computational fluid dynamics based on the Reynolds–averaged Navier–Stokes equations. Firm conclusions on the magnitude of the results could not be given. However, a good correlation in global design trends of lift–over–drag ratios has been observed between the results of BWB–Q3D and the high–fidelity computational fluid dynamics. Computations were performed in cruise conditions (Mach 0.7, Mach 0.75 and Mach 0.8) on two different geometries. An extensive analysis of blended–wing–body cabin–sizing approaches has been performed in order to determine the differences in accuracy in a worst-case scenario. The inside–out approach of the Cabin Configurator has been compared with the tube–and–wing–tailored outside–in approach, often pursued in the research field. In analyzing several thousands of cabins, it has been shown that an average overestimation between 7% and 22% in cabin capacity results from following the outside–in design approach. Finally, a new aircraft cabin sizing method has been outlined, the hybrid approach, based on combining cabin width dimensioning with pre–defined cabin length determination. An average decrease of more than 50% in cabin area sizing error is obtained when following this method instead of outside-in. No dedicated interior–sizing tool such as the Cabin Configurator is required, making this method easily applicable within the blended–wing–body research field.","blended wing body; cabin sizing; BWB; conceptual aircraft design; aerodynamic analysis","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:9c81ea64-37a4-4781-9247-2d42cb439e19","http://resolver.tudelft.nl/uuid:9c81ea64-37a4-4781-9247-2d42cb439e19","A Multidisciplinary Optimization of Composite Space Enclosures","Koerselman, J.R.","Vos, R. (mentor); Brander, T. (mentor)","2012","A design methodology for composite space enclosures was generated. As a result a panel of an electronics housing structure, as part of a general satellite traversing both GEO and LEO, was designed and optimized. A mass saving of 18% was achieved over a conventional aluminum panel, while assuring structural integrity for acceleration loads, avoiding vibrational resonance with other satellite components, allowing electrical conductance, providing sufficient radiation protection from the harsh space environment and at the same time assuring manufacturability. The optimized structure was composed of layers of carbon fiber composite and tungsten foils. For radiation purposes the layers were placed asymmetric around the geometric midplane, resulting in shape distortions due to residual thermal stresses from the curing process. These shape distortions were kept to a minimum. The validity of the theoretical models was assessed by means of testing for shape distortions, radiation attenuation, bonding strength and electrical resistivity. The bonding of the tungsten with the prepreg material was found to be problematic, but an improvement in lap shear strength was found with respect to methods proposed in the literature. A chemical etching surface treatment with a reduced etching time of one minute was proposed for the tungsten foils.","multidisciplinary; optimization; composite; space; enclosure; tungsten; surface treatment; SIDER; induced shape distortions","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration & Operations","","Design, Integration and Operations of Aircraft and Rotorcraft","",""
"uuid:dee2d842-ca91-4086-8ef8-771cfee1b0dc","http://resolver.tudelft.nl/uuid:dee2d842-ca91-4086-8ef8-771cfee1b0dc","Aerogravity assists: Hypersonic maneuvering to improve planetary gravity assists","Hess, J.R.","Mooij, E. (mentor); Sudmeijer, K.J. (mentor)","2016","Interplanetary missions use gravitational slingshots around planetary bodies to adjust their heliocentric velocity or inclination for quite some time. The momentum exchange that can be achieved during a so-called gravity assist is limited by the mass of the planetary body. To overcome this limitation, an aerogravity assist was proposed, a maneuver where, in addition to the gravitational forces, use is made of aerodynamic forces to increase the bending angle of the velocity, hence increasing the momentum exchange. To investigate how efficient an aerogravity assist can change the interplanetary orbital inclination and velocity, a simulator was developed that is capable of simulating both the gravitational and aerodynamic forces on a vehicle during an aerogravity assist. It was determined that waverider is a type of vehicle suitable for aerogravity assists due to their large lift-to-drag ratio, which reduces the energy dissipation in the atmosphere. The aerodynamic characteristics of a number of waverider shapes were evaluated, after which the one with the largest lift-to-drag ratio was selected. Furthermore, a numerical optimization algorithm was used to develop a reference trajectory planner. Finally, a guidance algorithm based on the tracking of drag accelerations was developed and tested to investigate if the found trajectories would still be feasible under the influence of uncertainties and perturbations. The angle over which the trajectory is bent is a measure for the effectiveness of the aerogravity assist. Using the reference trajectory planner, the maximum possible atmospheric bending angle was investigated for an aerogravity assist at Mars and Jupiter for different initial velocities. From this analysis, it was concluded that extremely high velocities were involved in the aerogravity assist at Jupiter, which resulted in large mechanical and thermal loads. These loads would limit the achievable bending angle when the velocities become too large. For the entry velocities investigated, the velocity bending angle could be increased by 10% for high entry (80.0 km/s) velocities and up to 143% for a relatively low entry velocity (68.0 km/s). For an entry velocity of 80.0 km/s, the initial heat-flux peak exceeded the imposed constraints, which prevented the optimization algorithm of finding any solutions. The maximum velocity bending angle that could be achieved at Jupiter was 125.1 degrees at an entry velocity of 68.0 km/s. At Mars, although the heat loads were still larger than for an Earth entry, it is believed that thermal protection systems can be designed that could handle the heat loads. The velocity bending angle could be increased by 490% to 818% depending on the arrival velocity, with a maximum velocity bending angle of 178.5 degrees at an entry velocity of 9.0 km/s. To investigate the effect of an aerogravity assist on an actual mission, two existing missions has been selected: Rosetta for Mars and Ulysses for Jupiter. Although both spacecraft did not have an aerodynamic shape, which means an aerogravity assist could not have been performed during the actual mission, it has been assumed that these vehicles would have had the geometry of a waverider. During the investigation of Rosetta swing-by at Mars, a reference trajectory was generated to investigate the amount of velocity decrease that could have been achieved using an aerogravity assist. It was determined that the reduction in velocity could be increased by 167% with respect to a gravity assist: from 2.3 km/s for a gravity assist to 6.2 km/s for an aerogravity assist. For Jupiter, it was investigated if the orbital inclination could be changed using the aerodynamic force only. As the entry velocity exceeded 80.0 km/s, the heat flux constrained was removed from the trajectory optimization to allow the optimization algorithm to find solutions. It was possible to change the orbital inclination by 54.2 degrees, but at an extremely large heat load of 40,620 W/cm2. This reconfirms that even though orbital inclination changes are possible using aerodynamic forces, Jupiter is unsuitable for aerogravity assists due to the high velocities and large heat loads associated with an atmospheric maneuver at this planet. Finally, using the aerogravity assist trajectory found for Rosetta, which was generated generated with the reference trajectory planner, the guidance algorithm was tested. The guidance algorithm was capable of tracking a drag reference under the influence of uncertain initial flight-path angles. The maximum offset in velocity bending angle occurred for a steep entry and was 1.06 degrees while the maximum offset in hyperbolic excess velocity occurred during a shallow entry and was 1.88 m/s. Furthermore, the tracking was also successful when a more accurate atmosphere model and perturbations were taken into account. For this analysis, the maximum offset in velocity bending angle and hyperbolic excess velocity were 1.24 degrees and 2.14 m/s respectively.","astrodynamics; aerogravity; gravity; assist; optimization; hypersonics; waverider","en","master thesis","","","","","","","","2017-02-24","Aerospace Engineering","Astrodynamics and Space Missions","","Space Exploration","",""
"uuid:29ddf25f-bcc3-47f3-9c26-53da9b6d9301","http://resolver.tudelft.nl/uuid:29ddf25f-bcc3-47f3-9c26-53da9b6d9301","Nonlinear Flight Control: Fault Tolerant Control with Sliding Modes and Control Allocation","Grotens, R.","Mulder, J.A. (mentor); Edwards, C. (mentor); Chu, Q.P. (mentor); Van Kampen, E. (mentor)","2010","Nonlinear Dynamic Inversion (NDI) is a promising method for Fault Tolerant Flight Control. The NDI algorithm cancels out the aircraft dynamics based on a dynamic aircraft model such that the closed loop system behaves linearly. The aircraft model is estimated online, which allows it to accommodate changes in the aircraft configurations and failures. It is important that an accurate dynamic aircraft model is provided in order to minimise the parasitic dynamics of imperfect dynamic inversion. Sliding Mode Control (SMC) feedback is applied to increase the robustness of the NDI algorithm especially in the case of a failure. SMC is well known for its strong robustness properties and controls the system using brute force. 1st order SMC is a discontinuous control algorithm and the chattering behaviour is highly undesired in practical applications. Therefore 2nd order SMC is applied on the critical rate control loop. This algorithm is less sensitive to noise and the control signals are continuous. It is shown that SMC can accommodate large uncertainties originating from control allocation error. Constraining the control solution minimises the parasitic dynamics and reduces the load on the feedback controllers. The Control Allocation problem is written as a low complexity linear program. For load balancing purposes the control solution is shaped with the Pseudo-Inverse.","Fault Tolerant Flight Control; Nonlinear Dynamic Inversion; Sliding Mode Control; Control Allocation","en","master thesis","","","","","","","","2016-06-01","Aerospace Engineering","Control and Simulation","","","",""
"uuid:3e7cb93b-7d3b-4b33-bcc0-d562630f12e7","http://resolver.tudelft.nl/uuid:3e7cb93b-7d3b-4b33-bcc0-d562630f12e7","Ready for Take-Off: Scaled Flight Testing","Van Gorcum, J.J.","Veldhuis, L.L.M. (mentor)","2017","Atmospheric free flight scaled flight testing is an affordable way to investigate the dynamic properties of an aircraft, while enabling a wider range of test possibilities than a windtunnel. This research is the first step into the development of a scaled flight testing model and as such will highlighted the difficulties and discrepancies which will be faced when scaling is performed. This study has the objective of investigating the effect of scaling on the aerodynamic properties and of the flow field at the tail location, with the focus on take-off conditions. The full scale case is a regional aircraft, the ATR72, with an unswept and slightly tapered wing. The scaled case is 14.7% geometric scaled The analysis of the aerodynamic properties is split between the clean wing and the wing with an additional surface in the form of a flap. The aerodynamic properties investigated were the lift, moment and drag curve, and the maximum lift coefficient. The clean wing was analysed using a quasi-3D analysis called Q3D, which is a combination of a vortex-lattice method (AVL) and a vortex panel method (XFOIL). A modification of XFOIL, called RFOIL, is used to analyse the difference in maximum lift coefficient between the airfoil of the scaled and full scale case. RFOIL is selected because of the better results near stall. The wing with flap is investigated using a vortex lattice method, in this case again AVL, where the airfoil with flap is investigated using the Euler-solver MSES. Finally the maximum lift coefficient for the wing with flap is analysed with the semi-empirical Pressure Difference Rule. The Pressure Difference Rule states that there is a ratio between the peak pressure and the trailing edge pressure, on a surface, at which maximum lift occurs. The methods are limited in their incorporation of viscous effects, the 2D-analysis tools (XFOIL, RFOIL and MSES) only include viscous effects in the small boundary layer region. AVL does not include viscous effects directly, but only via a correction factor for the lift-curve slope. However, the results found in literature using these methods are satisfactory. An analysis of the wake field is done using methods developed by the ESDU. The wake properties of both the scaled as well as the full scale are calculated using semi-empirical models and use a simplification where to place the vortex sheet. The dimensions and velocity loss of the wake itself can be calculated using either a method by ESDU or a method by Schlichting. Results showed that both these methods provided similar solutions. The scaling of the wing proves to change the aerodynamic properties and the similarity is no longer present for all the investigated aerodynamic properties. For both the wing with and without flap this is the case. These differences are mainly due to Reynolds number effects, the Mach number effects are only minimal on the lift coefficient. Due to the limits on the selected methods the exact magnitude of the difference found can not be guaranteed, but the trends in the found differences are certain. A basis for this is found in the different boundary layer properties, the scaled wing exhibits a thicker boundary layer, leading to a decambering effect, and laminar separation bubbles are found to occur. Both the clean and wing with flap shows more outboard loading for the scaled wing. The scaled wing exhibits a thicker wake, with a larger velocity loss. The difference between the full and scaled clean wing is thus larger than the difference between the full and scaled wing with flap. The reason for difference between the full and scaled wing can be found in the increased drag (coefficient) of the scaled wing. The reason behind the larger increase in wake for the clean wing is due to the fact that the difference in drag coefficient between the full and scaled case is larger for the clean wing than for the wing with flap. An investigation to minimize the differences between the full and scaled wing is done. It is decided to change the airfoil shape. Improvements are visible for the optimized airfoil, on all the aerodynamic properties. The optimized airfoil shapes tends towards a thinner airfoil and thus an investigation into solely optimizing the thickness of the airfoil is also done. This also proves to give better results than the original airfoil, however, not as good as the shape optimized airfoils.. This thinner profile was also investigated in the configuration with a flap, but here it proved to decrease the performance of the airfoil with flap. The difference between the full and scaled case can be reduced by an optimization. If an optimization is to be done, it must be done on the whole of configurations and flight conditions. As the next step into a development of a scaled flight test model, the exact extend of tests must be determined, only then can it be investigated how scaling affects the results of testing. No direct solutions exist to completely overcome the gap between the full and scaled aerodynamic properties of a flight testing model, however airfoil shape optimization does provide a better similarity.","Scaled Flight Testing; Aerodynamic properties; Wake; Flap; Similarity; Scaling; Optimization; MSES; RFOIL; XFOIL; Q3D; AVL","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:e32d1144-b1b6-48de-9313-5a5c86382ee1","http://resolver.tudelft.nl/uuid:e32d1144-b1b6-48de-9313-5a5c86382ee1","Flexible wind turbine blades: a FEM-BEM coupled model approach","Verelst, D.","van Bussel, G.J.W. (mentor); De Broe, A. (mentor); Barlas, T. (mentor)","2010","The global scope of the investigation considers the modelling of flexible wind turbine blades. Due to the increase in blade size and ever present push for better blades (in any way), less stiff blade design are (re-)entering the horizon of engineers. It is argued that due to the complexity of a flexible blade design, current modelling techniques have to be adapted or at least reviewed against new designs. In order to be able to capture the complex deformations of flexible blades (which in this case also includes structural couplings due to manipulated fibre lay-up strategies in the composite glass fibre epoxy material of the blade), a finite element analysis is required. For the aerodynamic modelling, the blade element and momentum theory is expected to give satisfactory results under fast computation times. Computational fluid dynamics is considered too time consuming (with respect to both computation times and modelling) if to be considered in an engineering friendly environment which focuses on design and analysis of multiple cases.","","","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:54095f89-e44d-4ea6-a48c-93ba4ac9127f","http://resolver.tudelft.nl/uuid:54095f89-e44d-4ea6-a48c-93ba4ac9127f","Trend validation of SHIPFLOW based on the bare hull upright resistance of the Delft Series","van Mierlo, K.J.","Bakker, P.G. (mentor)","2006","In 1977 Dawson published a paper in which he describes how to linearize the non linear boundary conditions at the free surface such that the potential ow around a ship can be calculated. This paper started the development of non linear free surface potential ow solvers which are used in a lot of ship research facilities nowadays. This CFD method is now mature and it has come within reach of the average sailing yacht designer. Most sailing yacht designers use empirical formulas based on the towing tank results of the Delft series to determine the resistance of a sailing yacht. Before they will start using CFD their question will be: How reliable are the CFD results? This leads to the main subject of this report: validation of a non linear free surface potential ow solver (SHIPFLOW) based on the bare hull upright resistance of the Delft series. First the possible errors in the towing tank data are analyzed. Then a verification of the non linear free surface potential ow solver is done. The predicted wave resistance values of the CFD code are compared with the residuary resistance from the towing tank tests. Correction equations based on the characteristic hull parameters are derived using linear regression analysis.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:16093448-e5bf-4ee7-a895-67168fc9e2c2","http://resolver.tudelft.nl/uuid:16093448-e5bf-4ee7-a895-67168fc9e2c2","Air Launch versus Ground Launch: A Multidisciplinary Design Optimization Study of Expendable Launch Vehicles on Cost and Performance","Van Kesteren, M.W.","Ambrosius, B.A.C. (mentor)","2013","During the entire era of space flight air launch is seen as a very promising concept. Despite its claimed advantages, air launch is up till now only a marginal success with the Pegasus launch vehicle from Orbital Sciences. In this study is investigated for which conditions expendable air launched vehicles can achieve a performance gain compared with expendable ground launched vehicles. The scope of this study is limited to near-term feasible concepts. Therefore, only existing carrier aircraft that require minimum modifications are evaluated. Solid propelled rockets are more promising for air launch than liquid rockets, therefore, only solid propelled rockets are considered during this study. Potential markets for launch vehicles with a 10 kg and 2,000 kg payload capability to low earth orbit are identified. The influences of different launch parameters and the presence of a wing on the potential performance gain of air launch are investigated. A Multidisciplinary Design Optimization (MDO) is deemed the most suitable approach for the comparison between air launch and ground launch. In earlier thesis work performed at the TU Delft a MDO tool in the Tudat framework is developed by Jan Vandamme. This tool is used as a starting point for this work but is heavily modified and expanded. Air launch can provide a reduction in the cost per flight between 26.9 and 31.3%. For a payload of 10 kg the gross take-off weight of the launch vehicle can be reduced with 66.7-70.1% while this is 33.6-47.4% for the 2,000 kg payload class vehicles. Moreover, air launch reduces the amount of ?V required to orbit with between 935 and 1,225 m/s compared to ground launch for a 10 kg payload for subsonic launch conditions. The ?V advantage of air launch for the 2,000 kg payload class is between 302 and 797 m/s. Winged vehicles provide a small cost advantage (2.45%) compared to wingless vehicles for horizontal launch as well as an advantage for the GTOW (19.9%) and the required amount of ?V to orbit (4.60%). As soon as a winged launch vehicle will be released under a positive flight path angle the cost advantage and the ?V advantage of the winged configuration will diminish quickly.","launch vehicles; expendable launch vehicles; air launch","en","master thesis","","","","","","","","2014-01-11","Aerospace Engineering","Space Engineering","","Astrodynamics & Space Missions","",""
"uuid:18dee61c-9828-430a-9d71-5a12586da89c","http://resolver.tudelft.nl/uuid:18dee61c-9828-430a-9d71-5a12586da89c","Studying the effect of the tail on the dynamics of a flapping-wing MAV","Rijks, F.G.J.","De Visser, C.C. (mentor); Karásek, M. (mentor); Armanini, S.F. (mentor)","2017","The effects of horizontal tail geometry and position on longitudinal flapping-wing micro aerial vehicle dynamics were studied using wind tunnel and free-flight experiments. Linearised models were used to analyse the effect on the dynamic properties of the ornithopter. Results show higher steady-state velocity and increased pitch damping for increased tail surface area and aspect ratio. The maximum span width of the tail surface is also found to play an important role in determining dynamic behaviour, in particular when the distance between the tail surface and the flapping wings is large. Steady-state conditions can be predicted accurately using linear functions of tail geometry for this ornithopter. Predicting dynamic behaviour is more complicated and requires further study. However, the observed trends in some of the model parameters suggest that future models explicitly including the tail geometry may be used to design flapping-wing robots with desirable dynamic properties.","wing-tail interaction; Flapping-wing MAV; system identification; tail effects","en","master thesis","","","","","","","","2020-05-19","Aerospace Engineering","Control & Simulation","","","",""
"uuid:e661fcdd-6fe8-46e9-b5ea-51dabbd89175","http://resolver.tudelft.nl/uuid:e661fcdd-6fe8-46e9-b5ea-51dabbd89175","The transformation of GPS into NAP heights: Combining NAP, GPS and geoid heights to compute a height reference surface for the Netherlands","Oudman, R.J.","Klees, R. (mentor)","2006","GPS is used more and more for height determination. Resulting ellipsoidal heights don't give information about how the water flows. Therefore traditional height systems are used. In the Netherlands this is the NAP. To perform a transformation between both height system a geoid model is needed. This theses looks at the following issues, regarding the determination of this geoid model: - Comparison between EGM96 and EIGEN-CG03C for the Dutch geoid - Computation of a height reference surface out of GPS/levelling data only - The use of variance component estimation for computation of a height reference surface out of NAP, GPS and geoid heights","Dutch geoid determination; variance component estimation; height transformation","en","master thesis","TU Delft, Aerospace Engineering, Physical and Space Geodesy","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1ff626fb-177d-44b1-8095-091923eb8f3a","http://resolver.tudelft.nl/uuid:1ff626fb-177d-44b1-8095-091923eb8f3a","Fluid-dynamic characterisation of small-scale organic Rankine cycle radial-outflow turbine for renewable energy application","Druzdzel, P.","Pini, M. (mentor)","2017","Since the problem of global warming has been broadly considered as vital and due to constantly rising oil prices, further fossil fuels exploitation requires diametrical changes immediately. The demand for environmentally friendly improvements does not only entail searching for new resources but also utilizing those which are available and more importantly, renewable. Organic Rankine Cycle (ORC) is possibly the most flexible technology in terms of temperature level and capacity nowadays. It is often the only applicable means of conversion for external energy sources and is therefore a very active research area in the field. Project investigates performance of an unconventional, small-scale, three-stage radial outflow, ORC turbine as this component has proven to be critical in the system. Main content embraces steady and transient computational fluid dynamic simulations by means of Ansys CFX software and evaluation of loss mechanisms. The main project objective is to evaluate the performance of the machine at its design conditions and fluid-dynamic characterisation of the flow. Geometrical data has been obtained from TU Delft in-house mean-line code zTurbo for preliminary fluid-dynamic design of turbomachinery. The main findings of this work involve performance evaluation of an innovative mini-turbine configuration and the applicability of available loss estimation models. Although there are guidelines on designing conventional, larger, axial power plants, still little is known about research in the field of small-scale, radial outflow machines working with molecularly complex fluids. Overall total-to-static efficiency of the machine is 65.3% for a 0.1 mm tip leakage gap and sealed stators. It is higher, and in close proximity to the one of 63.1% obtained by mean-line prediction tool zTurbo. Thermodynamic processes undergone by the working fluid in mini-ORC ROT can be represented by velocity triangles at midspan with a 2.2% discrepancy in overall efficiency w.r.t. two-equation, steady RANS. Relatively uniform blade load, ability to apply tight clearance, tangential deflection in rotors due to Coriolis force and the relative motion w.r.t. the casing contribute to a decrease in 3D effects. This efficiency is expected to be slightly lower if tip leakage is imposed also on the stationary domains, possibly with even better match. Total pressure loss coefficient for the first stator, for the steady-state case without tip leakage is of exactly the same value (23%) as the one for transient simulation with free-slip endwalls, accounting only for two-dimensional effects, averaged over the oscillation period. For the rotor, where the endwall boundary layer is more disturbed, steady state case predicts this loss by 3 points higher w.r.t. transient case, which gives 28%. Together with small secondary losses predicted in the stator, accounting for only 14% of the overall loss, 2D estimation/optimisation methods can be possibly used to predict the performance. Naturally growing passage area, allowing for smaller flaring angle, contributes to a decrease in span-wise velocity components and diminishes 3D effects. Stage 1 proved to be more susceptible to tip leakage increase. Small aspect ratios, in the order of 0.5, in mini-ORC ramp up the impact of tip leakage vortex compared to larger blades. The poorest performance (total-to-total efficiency of 51.2%) has been noted for the third stage, which requires profile optimisation and stagger angle modification. Expectedly, increase in tip leakage gap in rotational domains, leads to rise in entropy, which is even slightly more perceivable in low-aspect ratio blades, such as Rotor 1. Good match has been found between CFD and zTurbo in terms of overall loss estimation. Discrepancies for Rotor 1, Stator 3 and Rotor 3 are 0.1%, 0.1% and 0.2%, respectively. For Stator 1, Stator 2 and Rotor 2 these discrepancies are higher, of 3.3%, 7.7% and 3.0%, respectively. The main design problems are: profile losses and 2D design, including shock interaction shown in the results from the transient simulation. It is expected that this work will make a long-standing contribution to the body of knowledge on loss mechanisms in small-scale ORC machines and it will help to build a more sustainable and cleaner world.","ORC; ROT; organic; Rankine; cycle; radial outflow; renewable; energy; mini-turbine; turbine; centrifugal; CFD; RANS; unsteady; transient","en","master thesis","","","","","","","","2017-01-30","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:159e3fc8-c543-429c-a36e-b8c6f4e374f2","http://resolver.tudelft.nl/uuid:159e3fc8-c543-429c-a36e-b8c6f4e374f2","Drag reduction through a streamlined aerodynamic design process: Development and implementation of a methodology to accelerate the aerodynamic design process in the preliminary phase of car design","Peeters, M.","Hoogreef, M.F.M. (mentor); La Rocca, G. (mentor)","2016","Continuous innovation is very important to stay competitive in today’s world. Automotive manufacturers are an excellent example of this evolution when looking to new vehicle concepts. But also behind the scene, they have to be innovative in order to be able to keep up this progression. Aerodynamics has a large influence on the total performance of the car, and therefore fulfils a very important role in this innovation story. Aerodynamics is absolutely not straightforward which makes it on the one hand difficult to deal with and to estimate it influences, but on the other hand, this creates an improvement potential. Today’s passenger cars are already aerodynamically optimised to a fairly large extent, meaning improvements become rather marginal. To be able to keep this tendency of improving in the future, the aerodynamic design process has to be adapted. The focus of this work will be on the reduction of the air resistance of cars, which has a large influence on its top speed and fuel consumption. Especially the latter is very important today and will even gain more importance for future cars. Earlier research has shown that 70% of the reduction of the air resistance and the corresponding Cx value is done during the preliminary aerodynamic design phase. This phase is characterised by a high design freedom and a low level of detail of the corresponding design. Due to this, this early phase invites for shape optimisation of the basic aerodynamic shape having much more potential to achieve a lower Cx value. At the end of this phase, all fundamental parameters, dimensions etc. that define the final car will be fixed in order to begin the further detailed design during which detail optimisation is only possible anymore. This fundamental difference between the early phase and subsequent detailed design is responsible for their difference in influence on the final achieved Cx value and reduction. In order to achieve a successful aerodynamic design in terms of air resistance, the importance of that early design phase cannot be underestimated. To prevent aerodynamic improvements from stagnating, this preliminary design phase has to be fully exploited. Those preliminary phase can be split into three specific sub phases, namely the initial phase, preliminary studies and concept phase. In the first, the high level targets of the car design will be determined, which the final design should comply with. After this, as much as possible information and knowledge about the design has to be gathered during the so called preliminary studies. This knowledge will be used to formulate thoughtful concepts for the subsequent concept phase where they will be assessed and developed further until one final design concept remains which should comply with all the earlier defined high level targets. The quality of the information and knowledge gathered during those preliminary studies is therefore critical for a comprehensive final design. This is valid for the whole aerodynamic design and by extension also the total car design. But as already said, this work focuses on the design of the car exterior in terms of Cx value. It was observed in this work that the current situation has potential for improvement. More specifically, it was noticed that the aerodynamic department is occupied mainly with detail optimisation instead of the more favourable shape optimisation during those preliminary studies. The reason for this is due to a combination of their minor influence on the car exterior design compared to the aesthetics department and the current process flow during those studies. This current process flow is very inefficient and contains too much time-consuming and repetitive manual work. This combined with the short timespan of those preliminary studies lead to a limitation of the gathered knowledge of the car exterior design that is investigated. This is the main reason why the aerodynamicists are currently doing mainly detail instead of shape optimisation. For the latter, more investigations of higher quality (higher order) are required, which the current inefficient process flow does not allow for. Therefore, the aerodynamicists are limited to detail optimisation because of this, which is explained more into detail in this work. Thus, adapting the current process flow to allow the aerodynamic department to do shape instead of detail optimisation was found to be the main solution to improve and further reduce the Cx value and prevent it from stagnating in the future. The current process flow of those preliminary studies was analysed in this work and a suggested methodology that could accomplish those improvements was formulated based on this. The main difference of this methodology compared to the current situation is the implemented closed-loop instead of the open-loop modelling of the aerodynamic behaviour during those preliminary studies. This requires a fully automated process flow, which is missing in the current situation. In order to be able to also work out this suggested methodology to a fully working process flow, an automated generation of the geometric variants have to provided. This was achieved by developing a parametric geometry model capable of instantly delivering the required geometric variant without human interaction. The parametric model is an approximation of the real car exterior geometry, but its accuracy was proved with relevant CFD simulations. The closed-loop surrogate modelling is realised by using a MATLAB-based toolbox, called SuMo-toolbox, which is implemented in the software framework of the developed methodology. A secure shell connection between this software framework in MATLAB and the Linux machine, on which the simulations are done, assures a stable and fully automated process flow. After this working out of the presented methodology, a reality-based use-case was done to estimate its potential for improvements compared to the current situation. Promising results were already obtained which also confirm the promised theoretical improvements in praxis. Also conclusions and recommendations for future work or alternative implementations and extensions of this methodology are formulated in this work. This work was meant as an initial step and incentive to apply this methodology in the current industry. Before this could be possible, further research and work has to be done to make it practically implementable. This new process flow means a drastic change of the current one. It is typical for large companies to be unwilling to take this step. But if this methodology could be further developed so that it could fulfil its supposed role, namely improving and further reducing the Cx value of cars, it will become an important tool in the (near) future for manufacturers to become or stay ahead of their competitors. Certainly in today’s world of increasingly strict economics, its role cannot be underestimated.","aerodynamics; automotive; preliminary design; car; air resistance","en","master thesis","","","","","","","","2016-02-10","Aerospace Engineering","Flight Performance & Propulsion","","","",""
"uuid:d8bde740-3dfe-4737-b209-5130ea4e3744","http://resolver.tudelft.nl/uuid:d8bde740-3dfe-4737-b209-5130ea4e3744","Improved Blockage Corrections for Two-Dimensional Profiles in Deep Stall: Experimental and Computational Analysis of the DU91-W2-250 Profile subject to Tunnel Wall Constraint","Landstra, F.W.","Bijl, H. (mentor); Timmer, W.A. (mentor); van Zuijlen, A.H. (mentor)","2010","Wind engineering is becoming an increasingly important field of research. The pursuit for larger and more efficient wind turbines make the accurate prediction of forces and moments on turbine blades evermore crucial. During wind turbine starts and stops the turbine blades are subjected to large angles of attack. At these large angles the flow over the blades is fully separated, the blades are in deep stall. The prediction of loads on turbine blades is based on the performance of its two-dimensional profiles. Profile performance is measured in the windtunnel and the data is corrected for the constraint the tunnel walls impose on the flow. For bodies subject to fully separated flow, tunnel wall corrections are based on empirically derived methods and for two-dimensional profiles spanning the windtunnel testsection, Boorsma (2003) has shown these methods to be relatively inaccurate.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a1d88ae5-35f2-4687-b132-ce78a749a2ee","http://resolver.tudelft.nl/uuid:a1d88ae5-35f2-4687-b132-ce78a749a2ee","A comparative study of long-term polar motion of terrestrial bodies","Stiefelhagen, M.","Vermeersen, L.L.A. (mentor)","2002","","polar motion; mars","en","master thesis","TU Delft, Aerospace Engineering, Astrodynamics and Satellite Systems","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b9319341-ae54-4b38-a25c-3972f3ac9062","http://resolver.tudelft.nl/uuid:b9319341-ae54-4b38-a25c-3972f3ac9062","Trajectory optimization for a mission to Neptune and Triton","Melman, J.C.P.","Ambrosius, B.A.C. (mentor); Noomen, R. (mentor); Ortega, G. (mentor); Biesbroek, R. (mentor)","2007","","interplanetary; optimization; gravity assist; swing-by; low thrust","en","master thesis","TU Delft, Aerospace Engineering, Astrodynamics and Satellite Systems","","","","","","","","Aerospace Engineering","","","","",""
"uuid:bc2146e6-fdaa-4be3-9e06-8e10a04362bf","http://resolver.tudelft.nl/uuid:bc2146e6-fdaa-4be3-9e06-8e10a04362bf","Solar Concentrator Demonstrator for PocketQubes","Pino, D.M.","Zandbergen, B.T.C. (mentor)","2016","Deployable systems for small satellites appear as an innovative solution to enhance the performance capabilities and enlarge the mission range of this category of spacecraft. Embedded within the research line in Solar Thermal Propulsion and the new mission Delfi-PQ, this project tackles the design, analysis, production and testing of a solar concentrator for PocketQubes. The project includes the optical, thermal and structural design of the device and the proposal of a new receiver for a Solar Thermal Propulsion engine. The research done demonstrates the capabilities of the concept.","space propulsion; micro propulsion; PocketQube; solar thermal propulsion; inflatable; concentrator","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","Space Systems Engineering","",""
"uuid:4e7a12c2-788e-4c1a-a5c2-0b6502ca4cc7","http://resolver.tudelft.nl/uuid:4e7a12c2-788e-4c1a-a5c2-0b6502ca4cc7","Improving the orbit accuracy of the Swarmsatellite constellation using Higher Order Ionospheric Corrections","Saroukh, H.","Visser, P.N.A.M. (mentor); van den IJssel, J.A.A. (mentor); Menicucci, A. (mentor)","2017","","","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:9178f436-a0c3-4365-814a-3b375b2231c9","http://resolver.tudelft.nl/uuid:9178f436-a0c3-4365-814a-3b375b2231c9","Topology Optimisation of Thin Membranes Applied on a Parafoil Rib","Thedens, P.","Abdalla, M.M. (mentor)","2015","Membrane structures have a wide field of application in modern engineering due to their low weight-to-area ratio, which is especially exploited in kite design. The internal pressure of ram-air kites has to be well distributed over all cells in order to maintain the aerodynamic shape. By cutting holes in each rib the stagnated air can provide the required pressure in each cell. The question is, where to cut the holes such that the structural performance does not cause a decrease in aerodynamic performance? For that reason the membrane finite element (FE) solver developed in TU Delft in combination with geometrically non-linear topology optimization was utilized. The membrane FE solver is based on the tension field theory which allows the use of low density meshes and still being able to determine the membrane states: taut, wrinkled, or slack. Topology optimization supplies the user with an optimum material distribution in a design space for a given load. The combination of membrane FE solver and topology optimization resulted in an efficient method, which successfully reduced slack and wrinkled areas in membranes. The rib structure was optimized in a combination of two flight conditions, and the results indicate hole positions similar to the real ram-air rib model.","topology optimisation; membrane; tension field theory; ram-air kite","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Computational Mechanics","","European Wind Energy Master (EWEM)","",""
"uuid:2ae8dc5f-85d9-4092-b8cc-78e77b2378e7","http://resolver.tudelft.nl/uuid:2ae8dc5f-85d9-4092-b8cc-78e77b2378e7","Regional Aircraft Design Space Exploration","Mahieu, T.","Vos, R. (mentor)","2016","Turboprop aircraft achieve higher propulsive efficiencies at lower speeds due to their engine’s ability to accelerate a high mass flow of air at low jet velocities. With the increased importance of environmental considerations in aircraft design, aircraft manufacturers are forced to open up the considered speed domain since a reduction in cruise speed can lead to savings in fuel consumption and carbon dioxide emissions. Therefore, it becomes increasingly relevant to investigate the potential benefits of applying turboprop engines in regional aircraft design. It is the objective of this research study to explore the regional aircraft design space of direct operating cost and Mach number by performing multi-disciplinary optimization on both turboprop and turbofan aircraft configurations while including mission profile parameters as design variables. In total, three regional aircraft configurations are considered in this master thesis, differentiating themselves based on the configuration lay-out and type of engine application: a low-wing turbofan, a high-wing turbofan and a high-wing turboprop configuration. The latter configuration requires the implementation of a methodology to size, locate and scale the nacelle, where no landing gear is stored, while the leading-edge high lift devices for both high-wing configurations are redefined to accommodate the engine presence in front of the wing. All aircraft configurations are equipped with an advanced engine concept, having an entry-into-service year of 2025. Furthermore, a range equal to 1950 nautical miles and a payload of 70 passengers are imposed on all regional aircraft configurations. At the same time, three off-design missions are constructed in order to assess the range sensitivity of the design space. Due to the variety in encountered cruise Mach numbers and altitudes throughout this study, a method is introduced to determine the mission profile parameters of an aircraft design, cruising at any possible combination of Mach number and altitude. Next to the definition of the regional aircraft configurations and the mission requirements, a model is developed within a multi-disciplinary optimization environment, able to evaluate the performance of turboprop engines by means of a Fortran code which predicts the propeller efficiency at every flight condition. After having validated the developed model, empirical relationships to estimate the propeller mass and engine maintenance cost are added, resulting from an assessment of different methodologies. Also, an approximation of a take-off strategy to improve the field performance of the high-wing turboprop configuration is implemented, based on a ‘rolling take-off’ procedure where the power setting is gradually increased during take-off. For a baseline fuel cost of 3 dollars per gallon, the optimal design for each range is found to be a low-wing turbofan configuration, operating at or near Mach 0.80. At a range equal to 1950 nautical miles, a 4.5% advantage in direct operating cost is achieved by this configuration compared to the most optimal high-wing turboprop design. When the fuel price is simulated to increase, the minimum direct operating cost design among all ranges shifts to the high-wing turboprop configuration, exemplified by a 3.8% decrease in direct operating cost over the most optimal low-wing turbofan design, for a fuel price of 6 dollars per gallon and a range equal to 300 nautical miles. It is therefore concluded that a potential for turboprop applications exists in regional aircraft design, considering the expected rise in fuel cost over the next years.","engine comparison; regional aircraft; multi-disciplinary optimization; design space exploration; propeller performance","en","master thesis","","","","","","","","2016-05-19","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:6672aa53-6ecc-4571-85b2-2d4aafbba5bd","http://resolver.tudelft.nl/uuid:6672aa53-6ecc-4571-85b2-2d4aafbba5bd","Trajectory Optimization for a Mission to the Solar Bow Shock and Minor Planets","Oldenhuis, R.P.S.","Noomen, R. (mentor)","2010","In November 2003 the Voyager 1 spacecraft pierced through the Solar system’s termination shock, followed by Voyager 2 in August 2007. These events marked the beginning of interstellar exploration by spacecraft, which caused a wave of renewed interest in the outer heliosphere throughout the scienti?c community. This thesis research investigated the feasibility of a mission to the Solar bow shock (the true interstellar boundary) at ?200 AU from the Sun; twice as far as the Voyager spacecraft. The techniques used in designing its trajectory were standard gravitational-assist manoeuvres and/or a single close-proximity flyby with the Sun, and both low-thrust and high-thrust propulsion systems were investigated. Minimum time of ?ight and maximum spacecraft dry mass were primary objectives, whereas the number and quality of minor planet ?ybys were secondary objectives. A maximum on the time of ?ight of 15 years was upheld, extendible to a maximum of 25 years in case the ?rst constraint could not be met or proved overly bene?cial to the other objectives. This constraint necessitated upholding a maximum of 3 gravitational-assist manoeuvres, which gave rise to a search space of 146 unique ?yby sequences. A novel optimization algorithm developed in this thesis (GODLIKE) identi?ed 3 feasible sequences, which were only feasible in combination with a high-thrust propulsion system. The most promising sequence (Earth/Jupiter/Uranus/bow shock) proved capable of reaching the bow shock with minimal risk and impact on the spacecraft’s dry mass. The best result found requires a ?V of 5.86 km/s and approaches approximately 14 minor planets to within 0.03 AU. The total time of ?ight could unfortunately not be kept below 15 years; technically feasible trajectories could only be generated for times of ?ight between 23 and 25 years. Despite the long time of ?ight, the results developed in this research do show that it is possible to traverse the entire heliosphere using time-proven and conventional means.","Trajectory optimization; Minor Planet; Interstellar","en","master thesis","","","","","","","","2010-05-01","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:d1cbfff6-5cad-4cf4-a0fd-8ef3d53a19c4","http://resolver.tudelft.nl/uuid:d1cbfff6-5cad-4cf4-a0fd-8ef3d53a19c4","Interval Forecasting for Airline Passenger Demand: An Application to Airline Network Development","Schot, C.E.","Lopes dos Santos, B.F. (mentor); Sharpanskykh, O.A. (mentor); Curran, R. (mentor)","2015","In the past forty years, the volume of air travel has increased tenfold. While demand growth for OECD markets has slowed down in recent years, there is still a potential for markets where air services are currently not provided. It is the goal of the airline network development process to locate these potentially profitable markets. One of the main tools to support this process is passenger demand forecasting. However, experience has taught us that forecasting is inherently uncertain. The primary goal of this thesis is to present how interval forecasts of passenger demand can be created by using Monte Carlo simulations. The results show that, by combining a causal econometric prediction model with interval forecasts of time-dependent parameters, it reliable interval forecasts for demand can be produced. The secondary goal is to demonstrate the effects of using these intervals in a simplified airline network development model. By using actual airline data, it was concluded that the robustness of this process increases. This is particularly relevant for airlines, as they require confidence when making decisions about the development of their network.","Passenger Demand Forecasting; Forecasting Uncertainty; Gravity Model; Airline Network Development","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Operations","","Air Transport and Operations","",""
"uuid:3d8058be-f82b-453b-a22d-ebd46280b869","http://resolver.tudelft.nl/uuid:3d8058be-f82b-453b-a22d-ebd46280b869","Stochastic Collocation with CFD robustness concepts for multi-dimensional stochastic space: Application to a transonic airfoil","Wang, H.","Dwight, R. (mentor)","2015","Computational simulations have developed to a phase where the inherent physical variability prevalent in computational models exerts a larger effect on the predictive results than the deterministic numerical errors. To aim for more accurate and realistic simulations of the physical systems, it is imperative to include the input uncertainties into the computational models and investigate their effects on the outputs of interest. In the field of Computational Fluid Dynamics (CFD), which features high non-linearity and complexity, the non-intrusive Stochastic Collocation method (SC) gains great popularity by the virtue of easy implementation and high convergence rate of its spectral basis. The main idea of SC is to constructs a surrogate response surface in the stochastic space by globally interpolating the sampling values obtained from the deterministic simulations. Therefore, like any other spectral method, it shows limitations in capturing local parametric steep gradient or discontinuity in the stochastic space. Besides, the convergence rate is deteriorated due to the Gibbs oscillations. These spurious oscillations, which amount to unphysical realizations, could result in falsely enlarged full confidence interval, e.g., the pressure distribution along the upper surface of a transonic airfoil. To provide more robust stochastic analysis, the Gibbs oscillations in the stochastic space need to be eliminated. To this end, the robustness concepts from the CFD community, Local Extremum Conserving (LEC), Monotonicity Preserving (MP) and Essentially Non-Oscillatory (ENO), are reformulated for the multi-dimensional stochastic space and incorporated into the Stochastic Collocation method. The proposed method is termed Stochastic Collocation with Essentially Non-Oscillatory (SC-ENO) robustness. Different from the traditional Stochastic Collocation method, the SC-ENO method first resolves the locations of the discontinuity in the stochastic space by enforcing the robust limiter to the surrogate response surface. Then the whole stochastic space is partitioned into disjoint smooth sub-domains bounded by the discontinuities. All the deterministic sampling points are classified into each smooth sub-domain. Finally, the model surrogate in each smooth element is constructed by interpolating the sampling points of the same class. The proposed discontinuity detection method is implemented for the $1$-dimensional space and extended to the multi-dimensional space by the so-called dimension-by-dimension approach. Hence, the deterministic multi-dimensional sampling points are structured and formed by the tensor product of $1$-dimensional nodes. As for the surrogate construction, the performance multivariate interpolation methods, \textit{i.e.}, Sauer-Xu Lagrange interpolation and the least interpolation, are compared in terms of the robustness and the accuracy. The least interpolation method is better than Sauer-Xu algorithm but it lacks robustness for certain distribution of the sampling points. To remedy this, a element-wise interpolation method matching the proposed discontinuity detection method is developed. One remarkable feature of the proposed SC-ENO method is being completely non-parametric. It is essentially a post-processing of the input sample realizations. When the deterministic sampling points are structured, it has been proved that SC-ENO is able to choose automatically either a piecewise or a global polynomial approximation based on the smoothness of the target solutions in each dimension of the stochastic space. Therefore, the robustness of the surrogate model is ensured while the efficiency of Stochastic Collocation method is maintained. The accuracy and convergence property of the proposed SC-ENO method is investigated for some numerical test functions with jump discontinuities. Although there is no obvious improvement of the convergence rate, especially for the statistical quantities, the issue of the Gibbs oscillations is solved. To see how SC-ENO performs for real problems with jump discontinuities or steep gradient in the stochastic space, it is applied to the shock tube problem with uncertainties in initial conditions and the transonic viscous flow over the RAE 2822 airfoil with uncertainties in inflow conditions. In both of these test cases, the accuracy, efficiency and robustness of the SC-ENO method are illustrated. It is shown that there are no unphysical overshoots in the full confidence intervals of the interested quantities with sufficient deterministic sampling points. Meanwhile, the performance of another approach dealing with the stochastic discontinuities, Subcell Resolution (SR), is investigated for these two test cases. It is concluded that the SC-ENO method is more suitable for the viscous flow problems whereas the SR approach performs better for the inviscid case. Using the same set of the deterministic sampling values, the results of some interested quantities of smooth nature are presented, where the spectral convergence property is obtained. Since the SC-ENO method works on the tensor product sampling points, it is prone to the curse of dimensionality for high-dimensional stochastic spaces. To reduce the computational resources, the proposed approach is combined with the sparse grid approach of both isotropic type and dimension-adaptive type. However, the numerical experiments shows that the robustness property of the SC-ENO is lost for the sparse grid case. A more efficient and robust scheme suitable for high-dimensional space is a future research topic.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics","","","","52.370216, 4.895168"
"uuid:4a49bb27-caac-4de0-b479-c41bfcf63244","http://resolver.tudelft.nl/uuid:4a49bb27-caac-4de0-b479-c41bfcf63244","Cooperative 4D-Trajectory Management for Future Air Traffic Control","Nagaraj, R.","Borst, C. (mentor)","2016","","","en","master thesis","","","","","","","","2021-12-22","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:6b210945-7004-430e-884e-72b27a7f5acc","http://resolver.tudelft.nl/uuid:6b210945-7004-430e-884e-72b27a7f5acc","Aircraft Performance Parameter Estimation using Global ADS-B and Open Data","Gloudemans, T.W.","Hoekstra, J.M. (mentor); Ellerbroek, J. (mentor); Sun, J. (mentor)","2016","To enable low cost open source ATM simulations the University of Technology Delft is developing an open source ATM simulator Bluesky. A method was developed to identify aircraft performance parameters using ADS-B and other open sources of data. The goal is to determine the operational flight envelope and get estimates for the lift- and drag coefficients. The method streams global ADS-B data from Flightradar24. By making assumptions on wind and flight strategies, estimation can be obtained for aircraft parameters. The nature of these assumptions limit the aircraft types being analyzed to commercial air-craft only. The method measures the operational flight envelope and estimates weight, lift and drag coefficients for multiple phases in flight. Next the operational flight envelope was compared to open data. Here it was found that the estimations showed similar values as the open data and that the operational flight envelope can be estimated using the method. The drag polar was compared to BADA, which showed a consistent underestimation of the drag polar.","ADSB; Big Data","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Simulation","","","",""
"uuid:33705b93-9450-4fd1-a17c-930fc8b38f17","http://resolver.tudelft.nl/uuid:33705b93-9450-4fd1-a17c-930fc8b38f17","Characterization and Testing of a MEMS-Vaporizing Liquid Microthruster for Small Satellite Propulsion","Van Wees, T.X.","Cervone, A. (mentor); Zandbergen, B. (mentor); Naeije, M. (mentor); Van Zeijl, H. (mentor)","2017","Active propulsion is required in order to further develop the capabilities of small satellites like CubeSats. At TU Delft a micropropulsion system is being developed based on a Vaporizing Liquid Microthruster (VLM), using liquid water as propellant. This research presents the manufacturing, characterization and testing of an existing VLM-design. It focuses on the thruster component of the propulsion system, which is called the MEMS-VLM. The breadboard model consists of an inlet module, multiple heating chamber modules and a nozzle, integrally manufactured using MEMS-technology. The heating chamber modules consist of flow channels etched in silicon, of which the walls support silicon carbide heaters. These heaters are suspended in the center of the cross-section. The nozzle is a two-dimensional convergent-divergent duct. Characterization and testing of the MEMS-VLMis done in a bottom-up approach. First, the geometry and electrical properties of the flow channels and heaters are characterized, after which the performance of the heating chamber and the nozzle are independently studied by models and experiments. In order to facilitate manufacturing, minor changes are implemented to the design of the nozzle, electrical interface and fluidic interface. With these changes, successful manufacturing of theMEMS-VLM is achieved. Microscope images show significant but acceptable deviations between design dimensions and manufacturing results. Furthermore, resistance measurements of the heaters indicate partial mechanical failures in 20 out of 154 measured heaters. The thermal behavior of the heating chamber is studied by means of analytical models for conduction and radiation and a one-dimensional steady state model for convection. The conduction study shows that the chamber wall temperature is homogeneous, while the suspended heaters formhot spots. The convection model is used to study whether sufficient heat transfer can be expected to fully vaporize the propellant flow. It is found that at a chamber wall temperature as little as 10 K above the boiling point, full vaporization can be expected. An experimental setup is made to test the heating chamber, ultimately attempting to validate the design and the performance models. The ability to power the heaters with constant current and measure the mass flow, pressure and dissipated power is demonstrated. Furthermore, amethod to determine the local chamber temperature based on the resistance of the heaters is presented. However, current leaks and partial mechanical failures are detected in the heaters during tests with nitrogen gas, which compromise the ability to operate with liquid water. Hence, full validation of the heating chamber models could not be achieved. With respect to future designs it is recommended to change to metallic heaters, which are placed outside the chamber. The silicon chamber wall then serves as a heat exchanger. It is furthermore recommended to change the capping wafer material to glass, so that the boiling process can be studied optically. A second experimental campaign is done to determine the performance of the nozzle, which is described by the discharge factor CD, the Isp-efficiency ´I sp and the thrust coefficient CF . Nozzle performance tests are carried out in vacuum, using gaseous nitrogen as propellant. The pressure is adapted in order to match the Reynolds number in the nozzle throat to the designed operating conditions. At a measurement Reynolds numbers of Rem ¼ 1400 the performance quality factors are found to be CD ¼ 0.68§0.06 (discharge factor), ´I sp ¼ 0.3§0.05 (Isp-efficiency) and CF ¼ 0.33§0.06 (thrust coefficient). The poor performance is primarily explained by excessive friction and rarefaction losses in the divergent section of the nozzle and are expected to improve when increasing the Reynolds number and when decreasing the expansion ratio. Design validation of the MEMS-VLM could not be achieved, as on various aspects the design is rejected. Nonetheless, the experimental approach has been successful in revealing critical design recommendations and demonstrating the ability to test a microthruster, improving the understanding and advancing the development of micropropulsion at TU Delft.","","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:0c5a1796-49d7-4e7d-9431-57448f9ce09a","http://resolver.tudelft.nl/uuid:0c5a1796-49d7-4e7d-9431-57448f9ce09a","Optimizing inventory planning for aircraft component maintenance","Alizadeh, K.","Curran, R. (mentor); Verhagen, W.J.C. (mentor)","2015","This research aims to improve the inventory planning for a logistical provider who offers aircraft component maintenance and availability to its customer. To this purpose, a classification model is introduced which makes use of two existing classification methods i.e. Analytic Hierarchy Process (AHP) and Cost Criterion in order to produce a superior classification strategy. Subsequently, the weights obtained through the classification are utilized in a Non Linear Integer Programming (NLIP) Problem in order to optimize the inventory levels. This integrated approach resulted into significant savings of up to 25%. In order to validate the suitability and robustness of the new model, its practical performance is verified through a series of discrete event simulations.","optimization; inventory; spare parts; classification","en","master thesis","","","","","","","","","Aerospace Engineering","Air Transport & Operations","","","",""
"uuid:7897c8cd-1435-4d39-9693-4eda558a3e6b","http://resolver.tudelft.nl/uuid:7897c8cd-1435-4d39-9693-4eda558a3e6b","Determination of the body force generated by a plasma actuator through numerical optimization","Hofkens, A.","Kotsonis, M. (mentor)","2016","In order to extract the body force field that is generated by a plasma actuator from velocity data, most researchers disregard the influence of the pressure gradient to obtain a spatial and temporal description of the body force field. There is however some discussion whether this assumption is valid or not. The current research tries to compute the body force field by using a numerical optimization procedure, using a \matlab optimization routine combined with an \openfoam solver which was adapted to accommodate for the body force term. Many simplifications had to be made to be able to perform the optimization in a reasonable amount of time, among which were a fairly coarse numerical grid, a first order discretisation scheme and a parametrization of the body force field. Due to this last simplification, no real conclusions can be drawn with regard to the spatial distribution of the body force, but the integral body forces in x- and y-direction display more or less valid behaviour and correspond to previous research. It is also shown that the pressure gradient has the same order of magnitude as the body force density in all 8 cases, which means that this research challenges the assumption that the pressure gradient is of little importance when trying to obtain the body force from velocity data.","plasma actuator; AC-DBD; optimization; body force","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","Aerodynamics","",""
"uuid:7de36b4e-32b5-4da7-836b-c8fa40eb254e","http://resolver.tudelft.nl/uuid:7de36b4e-32b5-4da7-836b-c8fa40eb254e","Aerodynamic Stall Modeling for the Cessna Citation II","van Horssen, L.J.","Pool, D.M. (mentor); de Visser, C.C. (mentor)","2016","In 2019 all air-carrier pilots are obliged to go through flight simulator-based stall recovery training. Therefore simulators will have to be equipped with accurate flight models at high angles of attack. This research shows which stall characteristics can be modeled using flight data from symmetrical induced, quasi-steady stalls. Furthermore a well-known stall model structure is used, based on Kirchoff’s flow separation theory. It is shown that the hysteresis effect can be estimated using quasi-steady stall maneuvers. Aerodynamic terms related to the pitch rate, however, are not identifiable using such maneuvers. Transient effects on the other hand, which are normally only expected with highly dynamic maneuvers, could be estimated using the accelerations caused by the stall buffet. Lastly a stall buffet model is proposed, based on power spectral density analysis of the acceleration measurements.","aerodynamic stall modeling; flight data model; Cessna Citation","en","master thesis","","","","","","","","2021-08-04","Aerospace Engineering","Control & Operations","","","",""
"uuid:99a5bf9b-427c-47fc-ac55-7c197781d951","http://resolver.tudelft.nl/uuid:99a5bf9b-427c-47fc-ac55-7c197781d951","Passive louver mechanism for small satellites","Verdonck, J.A.G.","Guo, J. (mentor)","2016","A miniaturisation trend in the satellite technology is clearly observable. The new generation of small satellites experiences very large thermal fluctuations, due to their high performance payload and low mass. Contemporary thermal control systems, applicable to small satellites, are mostly characterised by having either an insulative or a radiative function. Therefore, these systems can only compensate at one end of the thermal hysteresis. This thesis provides a solution to these large fluctuations, by generating a variable emissivity surface. This is a thermal control system that has a radiative or insulative function, depending on the temperature of the satellite. The thermal management system, developed in conjunction with TU Delft and Airbus Defence and Space Netherlands, is the HiPeR radiator with the following characteristics: lightweight, flexible, passive, simple and cheap. The radiator is based on the behaviour of penguins, and is comparable to bulky Venetian louvers, used on larger satellites. In cold condition a low emissive foil is exposed to space, to act as an insulator. In hot condition, a high emissive foil can radiate heat to space. A transition between these two functions is achieved via a deployment mechanism. The smart passive deployment system, made with shape memory alloy, in combination with the HiPeR (High Performance Radiator) technology, which is a very flexible and low mass radiator, allows to make a passive miniaturised louver mechanism. The developed louver mechanism had an initial technological readiness level of 1, which has been raised up till 3 - 4 with this project. The performance is as high as the current state of the art for passive variable emissivity surfaces applicable to small satellites. The emissivity modulation ∆ϵ, between radiation and insulation mode, is 0.45. With this performance, the louver is able to stabilise heavy thermal fluctuations. The current design can narrow the thermal fluctuations (which sometimes have variations larger than 40 or 50°C) with 10 to 15°C.","small satellites; spacecraft thermal control; shape memory alloy; mechanical two way shape memory effect; louver mechanism; variable emissivity surface","en","master thesis","","","","","","","","2018-05-24","Aerospace Engineering","Space Systems Engineering","","Space Flight","",""
"uuid:d7240211-f56d-4850-b20c-0a6199fe4b52","http://resolver.tudelft.nl/uuid:d7240211-f56d-4850-b20c-0a6199fe4b52","The employment potential of a Dutch offshore wind energy market","Mutze, C.","","","Wind energy is currently one of the fastest growing markets in the world. In the Netherlands the potential for onshore wind energy is not large because of siting problems. Therefore the focus in the Netherlands has shifted from onshore to offshore wind energy because the wind climate offshore is substantially better than onshore. For the Dutch industry, offshore wind is therefore a promising, but still uncertain business. The Dutch central planning agency (CPB) has performed a social cost benefit analysis about offshore wind energy (CPB 2005). The results of this analysis were not very promising. Although it was not the main reason, this negative outcome partly resulted in the cancellation of the government aid on offshore wind energy. In the report, which the CPB wrote, the employment effect of offshore wind energy was not taken into account because it was not considered to be an advantage of an offshore wind energy market. In this thesis this way of reasoning is questioned. According to Greenpeace and the EWEA (2002), wind energy is the most labour intensive energy source which exists. The main goal of this thesis is to show whether the employment effect of a Dutch offshore wind market should be considered as an important argument in favour of wind energy. The central question of this thesis is: What is the potential for the Dutch economy of a growing offshore wind energy market to 6000 MW in 2030, concerning created employment in a Dutch offshore wind industry? To be able to answer this question a case study methodology in combination with a hybrid model of life cycle analysis and input-output analysis is used. The NSW and Q7 offshore wind projects have served as case studies. The results of these case studies were extrapolated to a capacity of 6000 MW in 2030 taking into account learning curves and labour productivity growth. There is not only employment created, but also lost due to a decreasing demand for conventional energy. By taking into account the current and future capacity credit for offshore wind energy, the lost employment has been calculated. The results of this thesis are shown in Figure 1. The results in this table are net employment effects, which mean that they are corrected for the lost employment in the conventional energy sector. For each MW of offshore wind energy capacity 15.6 fulltime additional labour years will be created of which 5 labour years will be created within the Netherlands. The division of generated employment between the Netherlands and other countries does not seem in favour of the Netherlands","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2f341cd4-fb94-4dea-ac7e-ca2596afab71","http://resolver.tudelft.nl/uuid:2f341cd4-fb94-4dea-ac7e-ca2596afab71","Reusable Upper Stage Stability and Control during Reentry and Descent","Bentla, F.","Mooij, E. (mentor)","2017","","","en","master thesis","","","","","","","","2018-02-21","Aerospace Engineering","Space Engineering","","Astrodynamics & Space Missions","",""
"uuid:46ecc10e-2290-416b-bd0f-e3be9603246a","http://resolver.tudelft.nl/uuid:46ecc10e-2290-416b-bd0f-e3be9603246a","Validation of NewGust and a comparison with other wind gust simulation methods with respect to the load response of a wind turbine","de Wit, A.K.","Bierbooms, W.A.A.M. (mentor); van Bussel, G.J.W. (mentor); Mulder, F.M. (mentor)","2010","As wind turbines become larger and larger, optimization of material usage becomes relatively more important. The reason lies in the direct connection of material use with investment costs, which are becoming more important with larger turbines. For this optimization, proper fatigue analysis and assessment of the extreme loads is highly important. For the assessment of extreme loads wind gusts are important. Until now, gusts of a deterministic shape have been used, which is in contrast with the common practise for fatigue analysis. Therefore, Wim Bierbooms developed the NewGust method for simulating wind speed gusts of any desired length and amplitude at DUWIND. The validity of the resulting gust shape has already been proved by several articles, but until now nobody looked into the validity of the load response of a wind turbine resulting from wind gusts simulated according to the NewGust method.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","Sustainable Energy Technology","",""
"uuid:5ffe749f-81aa-42d1-aed5-2f07580e8078","http://resolver.tudelft.nl/uuid:5ffe749f-81aa-42d1-aed5-2f07580e8078","A numerical investigation into the aerodynamic characteristics of AeroCity","Van Sluis, M.","Gangoli Rao, A. (mentor)","2017","","AeroCity; Wing-in-Ground; WIG; ground effect; high-speed transportation; CFD; aerodynamics","en","master thesis","","","","","","","","2018-03-10","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:8254d7b9-9875-4abe-b794-10f25a79d93c","http://resolver.tudelft.nl/uuid:8254d7b9-9875-4abe-b794-10f25a79d93c","Maintenance Interval Adjustment: Designing a general model to determine possible interval adjustment for all RNLAF aircraft","Reuver, N.M.","Curran, R. (mentor)","2016","How does an organization that is mainly used to conduct maintenance to its aircraft according to manufacturers prescriptions adapt a method with which they can change and optimize their maintenance policies? This thesis report describes the state of the art in maintenance- and related reliability engineering that is used to obtain a step-by-step method for ’in house’ Aircraft Maintenance Programme (AMP) alterations. A summary of the proposed method in a single figure can be found in fig. 5-1. The method first contains a business part where organizational alterations and regulations are mirrored against some common Maintenance Steering Group (MSG) and Reliability Centered Maintenance (RCM) approaches to combine into a Maintenance Review Board (MRB)-cycle that can be applied to the Royal Netherlands Airforce (RNLAF). Secondly, a reliability analysis part that uses RNLAF life data from all 8 types of aircraft is designed with use of Weibull and Failure Mode Effect and Criticality Analysis (FMECA) theory. This combines into a 11-step model that closely follows aviation regulations and that should give the associated reliability engineers within the RNLAF the necessary tools to start assessing the AMP of aircraft that fall under their responsibility. Finally, the model is tested with two cases. The 125hrs lead-lag link inspection of the AH-64 Apache and the hydraulic pumps of the CH-47 Chinook proved to be sufficient examples to apply and verify the method. Life data is analyzed and all the steps of the model are performed, which has resulted in advice to change the 125hrs interval to 250hrs and to apply an inspection/replacement interval to the hydraulic pumps in order to proactively monitor the wear and preventively replace the pumps to reduce corrective downtime.","","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:cbdcf43c-d285-4e96-a053-88f2eca39f3c","http://resolver.tudelft.nl/uuid:cbdcf43c-d285-4e96-a053-88f2eca39f3c","Wake Dynamics Study of an H-type Vertical Axis Wind Turbine","He, C.","van Bussel, G.J.W. (mentor); Simao Ferreira, C.J. (mentor)","2013","Recent developments in wind energy have identified vertical axis wind turbines as a favored candidate for megawatt-scale offshore systems. Compared with the direct horizontal axis competitors they poss higher potentials for scalability and mechanical simplicity. The wake dynamics of an H-type vertical axis wind turbine is investigated using Particle Image Velocimetry (PIV). The experiments are conducted in an open jet wind tunnel with a turbine model of 1 m diameter constituted of 2 straight blades generated from a NACA0018. The turbine model is operated at a tip speed ratio of 4.5 and at a maximum chord Reynolds of 210,000. Two-component planar PIV measurements at the mid-span plane focus on vorticity shedding and horizontal wake expansion. Stereoscopic PIV measurements at 7 cross-stream vertical planes are performed to study tip vortex dynamics and evolution of 3D wake structures. Measurement at the turbine mid-span plane shows that the roll-up of shed vortex is triggered by wake interactions. Vorticity decay is asymmetrical with the faster decay rate at the leeward side. The faster windward wake expansion is attributed to the windward deflection of the tower wake. Wake recovery has not been observed in the horizontal measurement plane up to 4R downstream of the rotor. Experimental results on the vertical planes show that the tip vortex is stronger than the shed vortex in the horizontal plane. The strongest tip vortex is produced near the turbine axial plane (y/R = 0), and the in-rotor vorticity decay accounts for 60% - 90% of the overall decay. Near y/R = 0, tip vortices move inboard behind the rotor, whereas the turbine tower and the horizontal struts obstruct the inboard motion within the rotor swept volume. The rate of inboard motion is proportional to the vorticity strength. Due to weak vortex strength and strong blade blockage, tip vortices move outboard at two sides of the rotor primarily towards the windward side. Roll-over of vortex pairs contributes to the breakdown of vortical structure behind the rotor. Vertical wake recovery begins 4R downstream of the rotor, and the fastest recovery is observed near y/R = 0.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:a088d693-f0f9-4348-ba6f-e1be137367e3","http://resolver.tudelft.nl/uuid:a088d693-f0f9-4348-ba6f-e1be137367e3","Magnetic Assisted Take-off for Commercial aircraft","Eeckels, C.B.H.","Vos, R. (mentor)","2012","","magnetic; take-off; aircraft","en","master thesis","","","","","","","","","Aerospace Engineering","Design and Integration of Aircraft and Rotorcraft","","","",""
"uuid:5a7520f7-373d-44a5-9961-931ba9fdca15","http://resolver.tudelft.nl/uuid:5a7520f7-373d-44a5-9961-931ba9fdca15","A methodological approach for optimisation of product development processes by application of design automation","Mulder, A.","La Rocca, G. (mentor); Schut, E.J. (mentor)","2015","In the past decades a clear transition can be seen from fully human-based production techniques towards more automated systems. With the Product Development Process (PDP) being a potential source of competitive advantage the same trend of adopting more automation can be seen in the PDP. The application of automation can lead to large reductions in process lead time. The reduced lead time can be used to enhance product performance by assessing more design options in the same time, or to reduce the cost-of-delay and obtain a larger market share. It is clear that a reduction in lead time is worth an investment for companies and therefore automation can be adopted to improve the PDP performance. Both industry and academia acknowledge the lack of a quantitative method to assess the effect of the application of automation on the performance of a given process. Furthermore no methods are available to assess the effect of incremental automation. Another limitation is that most models investigating automation in the PDP only take into account a binary type of automation: either fully human or fully automated. This research aims at addressing these gaps of knowledge and the goal of this research is to develop a tool that provides more insight in the costs and benefits of automation in the PDP taking into account incremental automation and various levels of automation. To achieve the objectives a novel methodology is developed i) to model any PDP as a combination of a predefined set of specific activities and ii) to define different levels of automation for these activities. Subsequently, metrics are developed to measure the impact of different levels of automation on different activities, both in terms of activity lead time reduction and implementation cost. A simulator using Discrete Event Simulation (DES) is developed which utilises the proposed process model and metrics to analyse, among others, the lead time, automation investment cost and process cost for the overall process (for a given process architecture). Finally, the simulator is connected to an optimiser which tries to find the most convenient level of automation for each of the PDP activities, in order to generate a Pareto front to visualise the trade-off between the lead time reduction and required investment cost. The proposed methodology is extensively verified. Verification is performed for both the simulator and the optimiser. Based on this verification it can be concluded that with appropriate settings the optimiser manages to find Pareto optimal solutions for different levels of automation. Validation however remains limited to positive expert judgement due to scarce validation data. The proposed methodology and the analysis and optimization framework are demonstrated by application to an industrial case study. The case study concerns the conceptual design phase of an aircraft component, performed by a multinational aerospace enterprise. The case study successfully demonstrates the feasibility and applicability of this methodology and accompanying frameworks. Multiple Multi-Objective Optimisations are performed to trade off various objective functions. In this case study, specific activities in the process are identified to be more effective to automate. Results show that compared to the status quo, an investment in the lug sizing tasks of 7,1% of the investment cost of full process automation can lead to a potential lead time reduction of more than 40%. The proposed methodology proves to be successful in objectively quantifying the costs and benefits of automation in the PDP and subsequently selecting the optimal automation level.","optimisation; product development process; aircraft design; methodology","en","master thesis","","","","","","","","2019-08-14","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:2d38dd76-5425-49a3-a5c0-02a35360ef74","http://resolver.tudelft.nl/uuid:2d38dd76-5425-49a3-a5c0-02a35360ef74","Energy Absorption of Additively Manufactured Lattices: On biomimetic abstraction of structural principles toward increased energy absorption in lattice structures","Bots, M.J.","Rans, C.D. (mentor); Benthien, H. (mentor); Hegenbart, M. (mentor)","2017","Cellular solids are characteristically excellent energy absorbers due to their capacity to store large amounts of energy through compression. A bioinspired design approach identified the Pomelo fruit (Citrus Maximus) as a biological role model for energy absorption. Fruit peels’ biologically most important functions lies in the need to provide protection of the seeds from mechanical damage or other negative environmental influences. This qualifies such biological structures as role models for the development of novel structures that protect commodities from damage. The main structural principle extracted from the Pomelo is a density graded strategy. With maturing additive manufacturing (AM) technologies allowing unprecedented control over structural topology, controlled lattice structures can now be investigated . Using a class of AM, selective laser sintering (SLS), lattice structures were fabricated out of polypropylene and subjected to static and dynamic compressive loadings. The lattices were designed to determine the influence of the biomimetic density grading, cell shape and cell size in 3 distinct lattice configurations. Quasi-static simple compression results are compared to analytical micro-mechanical models, finite element method simulations and digital image correlation. Dynamic impact data is assessed using high-speed camera images and evaluated with an analytical momentum analysis. Data analysis is discussed and it is concluded that the density grading strategy beneficially influences the energy absorption. This is attributed to a combination of local plasticity manipulation and higher densification strains in static regime. In dynamic tests, the collapse initiation trigger led to controlled, more gradual collapse with lower corresponding loads.","cellular solids; 3D printing; pomelo; additive manufacturing; lattice; energy; adsorption; biometrics; SLS; compression; impact","en","master thesis","","","","","","","","2017-09-01","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:8644cdbb-ed72-4c02-a028-11597f33c65c","http://resolver.tudelft.nl/uuid:8644cdbb-ed72-4c02-a028-11597f33c65c","Development and Implementation of a Cost Assessment Methodology for Multidisciplinary Design Optimization of Aircraft","Page Risueño, J.","La Rocca, G. (mentor); Raju Kulkarni, A. (mentor)","2017","","KBE; MDO; cost; commonality; manufacturing; aircraft components","en","master thesis","","","","","","","","2022-01-19","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Flight Performance and Propulsion","",""
"uuid:dde8d42e-590a-465d-abaf-760ec304760f","http://resolver.tudelft.nl/uuid:dde8d42e-590a-465d-abaf-760ec304760f","Behaviour Trees for Evolutionary Robotics: Reducing the Reality Gap","Scheper, K.Y.W.","De Croon, G.C.H.E. (mentor); De Visser, C.C. (mentor)","2014","Evolutionary Robotics allows robots with limited sensors and processing to tackle complex tasks by means of sensory-motor coordination. In this paper we show the first application of the Behaviour Tree framework to a real robotic platform using the Evolutionary Robotics methodology. This framework is used to improve the intelligibility of the emergent robotic behaviour as compared to the traditional Neural Network formulation. As a result, the behaviour is easier to comprehend and manually adapt when crossing the reality gap from simulation to reality. This functionality is shown by performing real-world flight tests with the 20-gram DelFly Explorer flapping wing UAV equipped with a 4-gram onboard stereo vision system. The experiments show that the DelFly can fully autonomously search for and fly through a window with only its onboard sensors and processing. The success rate of the learnt behaviour in simulation 88% and the corresponding real-world performance is 54% after user adaptation. Although this leaves room for improvement, it is higher than the 46% success rate from a tuned user-defined controller.","Behaviour Tree; Evolutionary Robotics; Reality Gap; Micro Aerial Vehicle","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Control & Simulation","","51.989723, 4.375473"
"uuid:c42b2cc3-9ea8-4f94-acbb-403d019bbb81","http://resolver.tudelft.nl/uuid:c42b2cc3-9ea8-4f94-acbb-403d019bbb81","Experimental and numerical characterization of impact on composites for automotive applications","De Baerdemaeker, J.C.A.","Kassapoglou, C. (mentor)","2016","Following the EU-28 targets, in 2050 a reduction in total energy consumption of 70% compared to the 2008 consumption is required driven by weight reduction in the road transportation industry. Because of the high specific strength and stiffness of composite materials, introduction of advanced composites in the vehicle design is observed. However the introduction of composites leads to new design challenges. Failure of composites is challenging to predict because of the absence of plasticity, the many possible failure modes and manufacturing imperfections. This leads in industry to the necessity of extensive testing and including safety factors, increasing the development costs and limiting the weight-reducing potential. This research is therefore focussed on predicting the response and failure behaviour of composites subjected to an out-of-plane impact load. An experimental characterization is performed through testing, following the ASTM D7316 standard. Carbon-epoxy and glass-polyamide-6 specimens in quasi-isotropic and cross-ply lay-ups have been impacted using a drop tower with impact energies ranging from 7.6 to 90.9 Joules. In these tests, a modification on the standard is done in which the impactor's displacement, velocity and acceleration are determined during the entire impact using an optical pattern tracking technique with high-speed cameras. This test programme is extended with static tests, in which the same boundary conditions are used and the impactor is pushed in the specimen to the same deflection as encountered during dynamic testing. From this test programme, insights on the failure loads, failure modes and energy absorbed are gathered during the event and post-mortem through ultrasonic scanning and optical microscopy. These observations improve the understanding of the material response and indicate differences between the tested materials and the significance of strain rate effects on the results. The dynamic and non-linear impact on carbon-epoxy is simulated with analytical and numerical models. Numerical simulations are performed in ABAQUS/Explicit, predicting delamination with cohesive behaviour between the plies and ply failure with three different user material subroutines. These material models are based on the Hashin, Puck and Catalanotti failure criteria and are mainly differentiated by the incorporated stiffness reduction after failure, resulting in a significant differences in model complexity. The analytical model, as developed by Fardin Esrail, is based on the energy balance to define stresses and uses an averaging approach, equivalent to Whitney-Nuismer, to predict damage. Comparison of the different models and validation through comparison with the test results is performed, from which the main advantages and limitations of the models are assessed. By combining experimental observations with numerical and analytical solutions, the parameters affecting damage creation and residual strength have been captured and a predictive impact modelling approach is developed. This approach can be very useful in the future when designing and analysing efficient composite structures with increased residual strength in the presence of damage.","aerospace; automotive; carbon-epoxy; glass-polyamide-6; impact; experimental characterization; numerical characterization","en","master thesis","","","","","","","","2028-03-01","Aerospace Engineering","Aerospace structures and computational mechanics","","","",""
"uuid:2587eed1-8363-4665-b2cf-7fdff242e017","http://resolver.tudelft.nl/uuid:2587eed1-8363-4665-b2cf-7fdff242e017","Aerodynamic effect of canard on a blended wing body aircraft in transonic regime: A numerical study using SU2","Aswathanarayana Gowda, B.G.","Gangoli Rao, A. (mentor)","2017","","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Flight Performance and Propulsion","",""
"uuid:d54fa42f-d731-443a-8178-73531f87ec74","http://resolver.tudelft.nl/uuid:d54fa42f-d731-443a-8178-73531f87ec74","Highly Flexible lead-free piezoelectric composites- For vibration damping and noise cancellation application","Mascarenhas, N.T.","Groen, W.A. (mentor)","2015","Vibrations are inherent part in an aircraft system and supressing them has always been a technological challenge. Over the recent years, damping of mechanical vibrations is becoming increasing important to improve the reliability and performance of the aircraft systems and also increase the safety of passengers. As a response to these issues, much effort has been expended in the development and exploitation of damping materials. Among the various damping materials, piezoelectric particulate polymer composite have shown great potential towards damping due to the specialised damping mechanism based on the unique energy transferring effect between the viscoelastic polymer matrix and piezoelectric ceramic filler. As a results, the main objective of the master thesis is to develop a highly flexible and highly voltage sensitive vibration damper with piezoelectric particular composite. Lead free system with sodium potassium niobate (KNN) ceramics doped with lithium is identified has the suitable ceramic filler system applicable for this purpose. Hence, the effect of lithium dopant on dielectric and piezoelectric properties on the structured and random KNN/Epoxy composites is explored in order to identify the optimal ceramic filler composition with the highest dielectric and piezoelectric properties. To increase the passive damping potential of the composite, a flexible PDMS polymer matrix with excellent damping capabilities is selected and mixed with the optimal ceramic filler composition to investigate further on the piezoelectric voltage sensing properties in combination with the passive damping capabilities of the composite to be usable as vibration damper is presented. Finally, moving towards real-time application, feasibility study on processing relatively large area flexible piezoelectric sensor with high voltage sensitivity and capability of dampening vibrations is investigated.","lead free; piezoelectric composite; flexible","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration & Operations","","Novel Aerospace Materials","",""
"uuid:92868b2d-87c4-4e0b-9761-698dd54f02f9","http://resolver.tudelft.nl/uuid:92868b2d-87c4-4e0b-9761-698dd54f02f9","Cruise Performance Optimization of the Airbus A320 through Flap Morphing","Orlita, M.","Vos, R. (mentor)","2016","In the era of increasing aviation traffic the conditions are right to promote design of ambitious concepts. At Fokker Aerostructures attention is drawn to smooth in-flight shape morphing to produce a structurally functional Variable Camber Trailing Edge Flap (VCTEF). The deployment mechanism would fit into the flap, not limiting other functionality such as Fowler motion, while at the same time allowing small camber variations during cruise. This is based on the assumption that such morphing will bring performance improvements which are commercially interesting. The main goal of this research was therefore to predict these performance benefits and thus the applicability for a specific case of the Airbus A320 aircraft in cruise flight. This aircraft is large enough to accommodate the technology, it is operated in great numbers and cruise is the most fuel demanding part of its mission. Since the concept is in the development phase the further task is to determine the morphing design setup which performs best. The amount of morphing is driven by a circular reference function, which is added to the base geometry at any desired streamwise cut of the wing by manipulation of the airfoil coordinates as seen on the cover. The design is specified by the points on the airfoil upper surface where the morphing begins and ends, boundaries of the morphing region where upper surface bending is allowed. As also found in other literature it is shown that morphing can bring drag reduction for a section, wing and the complete aircraft. This varies throughout the cruise, which is translated to more sophisticated performance indicators for comparison and evaluation of the benefits. The first indicator is the increase of range over the design mission for the given aircraft. The second and third are the fuel savings which can either be obtained by increasing the cruise end weight, or by decreasing the cruise beginning weight, both by the amount of the saved fuel while keeping the aircraft range constant. In order to evaluate these indicators, the Breguet range equation is used in a discretized form, utilizing an interpolated lift-to-drag ratio determined by aerodynamic analysis at 7 cruise points. This was done using both the 2D solverMSES and a quasi-3D tool Q3D developed at TU Delft comprising ofMSES and AVL vortex lattice solver. For the analysis a complete A320 model is required, which was not available and was created from the known performance data and partially assumed geometry. The unknown wing geometry was optimized with respect to the mid-cruise drag simulating an already efficient aircraft, as suggested by literature. Other model components were the horizontal stabilizer, fuselage and center of gravity position allowing trim at the reference cruise points and obtaining the lift requirements for the wing and a representative section. Under these lift requirements the 2D and 3D analyses were performed at individual cruise points to obtained improved lift-to-drag ratios which could be then used to evaluate the range improvement. Itwas found thatwith morphing in 2Dthe drag reduction can amount up to 9% at the beginning of cruise but parabolically decreases towards mid cruise after which it remains below 0.5%. This is primarily due to manipulation of the shockwave and the boundary layer at the given lift requirements, which is most dominant at high cruise lift coefficients. Since the induced drag was found not affected by the assumed morphing, such improvements are further scaled down when evaluated for the entire wing and even further from the aircraft point of view, resulting in a range improvement in order of 20km and fuel savings of below 0.5% of trip fuel. A sensitivity analysis on the design variables has shown that these performance benefits have small sensitivity to the size of the morphing region and that a very aft located regions are the most beneficial, suggesting that a small tab at the trailing edge might be a better and easier solution. In view of these results the smooth morphing concept is deemed not applicable for the cruise of short range aircraft such as A320. However, given the parabolic behaviour of the drag improvements, larger potential can be expected for long range aircraft, which is the main resulting recommendation of the conducted research. Furthermore it cannot be excluded that other regimes could benefit more from the morphing concept, such as high-lift, which would probably require wind-tunnel testing, as discussed in the final Appendix of this work.","morphing; camber; transonic; drag; optimization; cruise","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Flight Performance and Propulsion","",""
"uuid:47b989e2-972f-48c7-8ee2-98a269931fa2","http://resolver.tudelft.nl/uuid:47b989e2-972f-48c7-8ee2-98a269931fa2","Detailed design and verification of a structure and mechanisms for Delfi-n3Xt","De Jong, J.P.","Brouwer, G.F. (mentor); Bouwmeester, J. (mentor); Gill, E.K.A. (mentor); Noomen, R. (mentor)","2012","The objective of this thesis is to perform systems engineering, detailed (re-)design and testing of the structural and mechanisms subsystems and facilitate the production of components.","Delfi programme; Delfi-n3Xt; CubeSat; satellite; stucture; mechanisms; structural; mechanical; systems engineering","en","master thesis","","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","Space Systems Engineering","",""
"uuid:5ba6ede0-6000-47ce-a229-2b65212a162f","http://resolver.tudelft.nl/uuid:5ba6ede0-6000-47ce-a229-2b65212a162f","Coupled Flight Dynamic and Unsteady Aeroservoelastic Modeling and Control of a Flexible Wing Aircraft","Tal, E.A.","Chu, Q.P. (mentor); Nguyen, N.T. (mentor)","2015","Recent developments in airframe design include the increasing application of modern lightweight materials. Airframe designs based on composite materials are able to provide sufficient structural strength at lower mass, but often have decreased structural rigidity. Flight vehicles with relatively flexible structures exhibit more prominent coupling of aeroelasticity and flight dynamics, and may suffer from degraded aerodynamic efficiency and decrease of control surface effectiveness. In order to address this issue, a multi-disciplinary approach to control effectiveness and aerodynamic efficiency of flexible aircraft is required. The purpose is not only to neutralize negative aeroelastic effects, but also to employ deliberate reshaping of the elastic wing to improve efficiency and handling of the aircraft. To this end, NASA is researching a novel type of control effector, the Variable Camber Continuous Trailing Edge Flap (VCCTEF). Using the multi-segment flaps of the VCCTEF, it is possible to adapt the camber of the wing in order to achieve an optimum lift distribution. In the context of aircraft with flexible airframes, a representation of flight characteristics based on a rigid-body 6DOF flight dynamic model is inadequate. The prominent coupling of flight dynamics, structural dynamics, and high-bandwidth control surfaces calls for coupled flight dynamic and aeroservoelastic modeling of flexible vehicles. The purpose of this thesis project was to develop such a coupled model for application during the conceptual design phase of adaptive aeroelastic wing technologies. A comprehensive flight dynamic and aeroservoelastic modeling approach for a flexible wing aircraft with VCCTEF in turbulent air was developed. Unsteady aerodynamics of the flexible wing and flap system were found using modified aerodynamic strip theory based on steady-flow vortex-lattice results and 2D unsteady aerodynamics models. Compressibility effects on the unsteady aerodynamics, based on the work by Beddoes and Leishman et al., were taken into account throughout the modeling effort and a comparison was made with unsteady aerodynamics for incompressible flow. In order to demonstrate the model and the effectiveness of the VCCTEF, a multi-objective flight controller for flight dynamic maneuvering, flutter suppression, and drag reduction was designed. Simulation results underline the potential of the VCCTEF as an enabling technology for adaptive aeroelastic wing shaping.","flight dynamics; aeroelasticity; aeroservoelasticity; unsteady aerodynamics; flight control; vcctef","en","master thesis","","","","","","","","2015-07-22","Aerospace Engineering","Control and Operations","","Control and Simulation","",""
"uuid:994a46e0-b56f-4121-aa93-ea17a0457daa","http://resolver.tudelft.nl/uuid:994a46e0-b56f-4121-aa93-ea17a0457daa","Superbus Positioning System: A High Accuracy Networked RTK GPS System","Pauwels, G.J.J.M.","Hanssen, R.F. (mentor); Tiberius, C. (mentor); Terzi, A. (mentor)","2011","In this report a high accuracy positioning system is investigated for use in the Superbus. The Superbus project is an effort to apply a new and complete conceptual approach to public transport. It consists of a vehicle, logistics and infrastructure. The positioning system for the vehicle is to have a horizontal position error, which will not exceed 5 cm in 95% of the obtained solutions. Secondary requirements included large (quasi-national) deployment area. Networked RTK positioning using GPS is shown to be a valid means to adhere to these requirements. Real Time kinematic (RTK) positioning allows for the required accuracy, while a base station network will allow for the required deployment area using Pseudo Reference Stations (PRS). UMTS is shown to be potentially effective for the required wireless data transfer using the NTRIP protocol. Testing con?rmed adherence of the Superbus Positioning System to the requirements in a variety of real world scenarios. Furthermore, the receiver is shown to perform to manufacturer speci?cations. Dif?cult environmental conditions, such as urban areas and multipath are con?rmed to have an effect on the position estimate in certain situations. It is however demonstrated that the receiver is capable of adhering to Superbus requirements in these situations, provided the initial ambiguity resolution is correct. Temporary signal loss of all satellites (for example due to an underpass) is shown to in?ict the need to reinitialise the ambiguity resolution algorithm, causing a temporary unavailability (around 20 seconds) of the precise RTK position estimate. Heading estimates are also established to be within speci?cations in good conditions. In high multipath conditions, or conditions with a low amount of satellites in view, the heading estimates exceed the manufacturing speci?cations with varying margins. This is possibly due to the fact that the ambiguities of the secondary antenna cannot be ?xed in this scenario. Material testing showed that carbon ?bre, the material that initially would cover the antennas in the vehicle, is highly un?t for this purpose. A thermoplastic counterpart shows no degradation of the satellite signal, and can be used for said purpose.","GPS; RTK; Superbus","en","master thesis","","","","","","","","","Aerospace Engineering","Mathematical Geodesy and Positioning","","","",""
"uuid:94394fa1-8722-4bd8-9568-b8167a00bb41","http://resolver.tudelft.nl/uuid:94394fa1-8722-4bd8-9568-b8167a00bb41","Aeroacoustics of Cavity Flow using Time-Resolved Particle Image Velocimetry","Parkhi, D.","Scarano, F. (mentor)","2009","The flow past open cavities is a problem that is encountered in many engineering applications and can result in intense acoustic tones. The flow physics and acoustics of cavity configurations are complex and both computational and experimental techniques are being developed to provide an opportunity to gain further understanding and provide a tool to predict not only cavity tone frequencies but their amplitude","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9bbcf030-af4b-42c8-a7e5-2157bde13706","http://resolver.tudelft.nl/uuid:9bbcf030-af4b-42c8-a7e5-2157bde13706","Development of a Parametric 3D Turbomachinery Blade Modeler","De Koning, R.C.W.","Pini, M. (mentor); Vitale, S. (mentor)","2015","Nowadays Organic Rankine Cycle (ORC) power systems are of paramount importance to exploit waste heat and renewable energy sources. Standard design rules and empirical models are mostly available for steam/gas turbines and can not be directly applied for ORC. Because of this, a redefinition of the design strategy is needed, starting from the turbine concept, passing through dedicated preliminary design optimization and eventually arriving at a complete new redefinition of the optimal blade profiles through advanced optimization methodologies. To fill the gap between (zero-dimensional) mean-line analysis and 3D fluid-dynamic analysis a Turbomachinery Blade Modeler (TBM) is required. The modeler not only gives direct control of the blade geometry but also provides valuable feedback of the design. This allows the user to construct a good initial design before refining it with more computationally expensive methods. The TBM is developed using the python API within the framework of the open source software FreeCAD. Furthermore, it is also tightly coupled to two mesh generators, an in-house one UMG (Unstructured Mesh Generator) and to the open source Salome. This link guarantees the quasi-automatic generation of high quality CFD meshes for any kind of blade design. The approach to construct a variety of turbomachinery blades is based partially on state-of- art parametrization techniques and uses fundamental design variables such as metal blade angles, chord length and the stagger angle. The geometry is purely build up with NURBS curves and surfaces which has the benefit that sharp edges are avoided and high smoothness of the profile shape is guaranteed. NURBS include control point position, weight and curve degree which allow a flexible control of the shape without introducing many variables, which is beneficial in optimization routines. The TBM allows for the design of any kind of blade: these include axial, centrifugal, centripetal, radial rotors/ impellers and mixed blades. Moreover, to aid the designer the flow passage area distribution can be visualized run time. The TBM has been already successfully tested for the design of a high loaded centrifugal rotor. Additionally, a complex twisted and flared axial compressor, the NASA Rotor 67 was reconstructed using the TBM. The small differences between the reference geometry and the reconstructed one were evaluated with 2D CFD simulations. Finally, a design of a radial-inflow turbine was reproduced and meshed for future analysis. The parametric 3D turbomachinery blade modeler has proven to be a very powerful tool for designing turbine and compressor stator/rotors. Moreover, after the consolidation of the algorithms and a direct coupling with the CFD solver SU2, the tool will be ready to be used as a turbomachinery optimization environment.","blade modeler; turbomachinery; axial; centrifugal; centripetal; radial; turbine; compressor; ORC; NASA Rotor 67; rotor; stator","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","Flight Performance and Propulsion","",""
"uuid:409cef9e-6a29-45c4-b54f-27839ecea614","http://resolver.tudelft.nl/uuid:409cef9e-6a29-45c4-b54f-27839ecea614","Ecological Interface Design: Training Air Traffic Control Novices in Conflict Detection and Resolution","Visser, R.M.","Borst, C. (mentor); Mulder, M. (mentor); Van Paassen, M.M. (mentor); de Winter, J.C.F. (mentor)","2016","Ecological Interface Design is an interface design framework developed for process control, and recently also in aviation. An example is the Solution Space Diagram, a visual decision-support tool for air traffic controllers in Conflict Detection and Resolution. Costly Air Traffic Control training with high drop-out rates spurs research to improve training methods. This paper presents research into the possible benefits of ATC training of novice controllers with the SSD interface. Predicted benefits include better performance and better decision-making-behavior, due to the cognition support during the novice training. A human-in-the-loop experiment with sixteen participants was performed, where participants were trained, and later tested, in solving aircraft conflicts of different geometrical orientations. Objective performance data of trainee solutions showed slightly better performance and longer response times for the group training with the SSD. Subjective behavioral analysis recorded more goal-orientated behavior opposed to task-oriented behavior, hinting at a higher situation awareness and a more critical decision-making process, especially in near perpendicular and unequal arrival conflict types. Whether this behavior, with more reflection during decision-making, could be valuable for a deeper understanding and improvement in the learning process is yet to be tested, as the longer response times contradict with the decisiveness expected from operational air traffic controllers. Further research is needed to statistically confirm the initial findings.","Ecological Interface Design; Novice Training; Air Traffic Control; Conflict Detection and Resolution; Decision Ladder","en","master thesis","","","","","","","","2021-02-01","Aerospace Engineering","Control and Operations","","Control and Simulation","",""
"uuid:84ae2335-bda6-4880-af3e-217cd6289f27","http://resolver.tudelft.nl/uuid:84ae2335-bda6-4880-af3e-217cd6289f27","ICESat full waveform signal analysis for the classification of land cover types over the cryosphere","Molijn, R.A.","Lindenbergh, R.C. (mentor); Gunter, B.C. (mentor); Klees, R. (mentor)","2009","The Earth needs attention. That is the bottom line of today’s discussion on the impact of humans on the environment and their contribution to global warming. With the rapid sea level rise and the melting ice caps, it is becoming increasingly important to understand these processes. Mass balance estimates of the cryosphere (e.g. Greenland and Antarctica) are one of the keys to unlocking the secrets of today’s concerns and predicting tomorrow’s problems. The primary objective of this research is to construct an automatic classification algorithm to that will distinguish between the polar land cover types: ice, rock, snow and water. The algorithm is based on full waveform laser altimetry measurements gathered by the Ice, Cloud and Elevation Satellite (ICESat). The results of this research have the potential to play an important role in improving the current methods for computing mass balance estimates and monitoring seasonal changes in land cover type of the cryosphere.","ICESat; full waveform analysis; laser altimetry; classification; land cover types; cryosphere; polar regions","en","master thesis","","","","","","","","","Aerospace Engineering","Geomatics","","","",""
"uuid:be8c1ad4-a630-4b24-b108-6682d84fa8b4","http://resolver.tudelft.nl/uuid:be8c1ad4-a630-4b24-b108-6682d84fa8b4","Europan tidal deformation: Providing a theoretical framework for altimetry data to determine ocean presence","Van Barneveld, P.W.L.","Naeije, M.C. (mentor); Vermeersen, L.L.A. (mentor)","2005","","jupiter moon europa; tidal deformation","en","master thesis","TU Delft, Aerospace Engineering, Astrodynamics and Satellite Systems","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d1c58f2e-40dc-43c6-8383-f2041593d1c4","http://resolver.tudelft.nl/uuid:d1c58f2e-40dc-43c6-8383-f2041593d1c4","Effects of Increasing Aerothermodynamic Fidelity on Hypersonic Trajectory Optimisation for Flight Testing Purposes","Van Oostrom, J.","Schrijer, F.F.J. (mentor); Mooij, E. (mentor); Sudmeijer, K.J. (mentor)","2015","In a previous study, the optimal re-entry trajectory of Hyperion-2 has been derived. The mission of the vehicle is to measure hypersonic boundary-layer transition, a phenomena in which the laminar boundary layer turns into a turbulent boundary layer. This is an important feature in hypersonic flow to investigate, as it introduces peak heating and increases drag. A constant Mach 10 flight has been performed, optimising for flight time, whilst maintaining a large Reynolds number range, in which transition occurs (Retrans = 106). Hyperion-2 is a theoretical experimental vehicle studied at Delft University of Technology. The aerodynamic coefficients of Hyperion-2 in the previous study have been obtained using a modified Newtonian panel method. In present thesis, the aerodynamic coefficients are computed using an open source computational fluid dynamics software called SU2 (Stanford University Unstructured). Simple geometries have been used to verify and validate the solver, focusing on shock position and shape, pressure distribution and heat flux. Using an open source mesh generator called GMSH, a three dimensional unstructured grid of Hyperion-2 has been generated. With this grid, the aerodynamic database consisting of 120 combinations of Mach number and angles of attack has been created. The database has been used to create a new optimal trajectory for the Hyperion-2 mission. During the presentation, the differences in aerodynamic coefficients are evaluated and the effect on the optimal constant Mach 10 flight trajectory is presented.","hypersonic; trajectory; optimisation; CFD; Computational; Fluid; Dynamics; Hyperion; Stanford; University; Unstructured; SU2","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:a8108c37-fe03-4554-84a7-c98b1f6359d0","http://resolver.tudelft.nl/uuid:a8108c37-fe03-4554-84a7-c98b1f6359d0","Aeroacoustic Investigation of Rod-Airfoil Noise based on Time-Resolved PIV","Lorenzoni, V.","Scarano, F. (mentor)","2008","The rod-airfoil configuration is a benchmark test case for aeroacoustic assessments of vortex- structure interaction noise. Several industrial devices are arranged in such a way that down- stream bodies are embedded in the wake of upstream bodies, such as gas turbines, high lift devices, helicopters among others. Aeroacoustic predictions usually rely on time dependent Flow field information obtained from CFD for the determination of the aeroacoustic sources. The present work proposes a novel approach for the aeroacoustic prediction of rod-airfoil noise based on time-resolved PIV experimental data. The aeroacoustic emission of a NACA0012 airfoil in the Karman wake of a rod is investigated by means of 2D TR-PIV in combination with beamforming and microphone measurements. First the time evolving velocity field around the airfoil is measured using high-speed PIV. The corresponding pressure field is then deduced by spatial integration of a Poisson-based algorithm for quasi-2D incompressible flows. Pressure and velocity computed on specific surfaces around the airfoil constitute the source terms of the implemented Curle's and Ffowcs Williams-Hawkings's aeroacoustic analogies. The calculated Sound Pressure Level (SPL) is compared with the measurements obtained by far field microphones. Velocity visualizations in the spanwise direction provide qualitative information about the phase coherence of the vortical impingement along the airfoil span. Parametric studies are performed to evaluate the effect on the acoustic prediction of the position of the integration surface and the numerical discretization methods employed. The vortex release-impinging mechanism revealed to be the main cause of the noise emission. Beamforming visualizations confirmed the major contribution of the airfoil to the total noise radiation. All the calculated acoustic spectra exhibit a main peak corresponding to the rod- shedding frequency. The high frequency components are the most affected by numerical and experimental noise. If the analysis is focused on the tonal peak of the computed spectra the method reveals an accuracy within 10 % of the measured SPL, varying with the spanwise correlation length. This provides good prospects for developments of experimental PIV-based aeroacoustic investigations.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:595417d2-a84f-4e12-8c02-a695de73d4c0","http://resolver.tudelft.nl/uuid:595417d2-a84f-4e12-8c02-a695de73d4c0","Attitude and orbital modeling of an uncontrolled solar-sail experiment in low-Earth orbit","Pirovano, L.","Noomen, R. (mentor); Dachwald, B. (mentor)","2015","Solar sails are big and lightweight structures that exploit the radiation from the Sun to propel the vehicle. They are very different from usual satellites since they yield a large moment of inertia, highly flexible parts and coupled attitude dynamics, orbital dynamics and structural vibrations. To these days studies that confirm the importance of investigating the elasticity of the sail in gossamer structures are available, but a full dynamics modeling that considers the coupling among the structural elasticity, orbital motion and attitude motion is still absent. The thesis is going to cover this subject. The thesis concentrates on Gossamer-1, a technology demonstrator that aims to test the deployment mechanism of a sail in LEO. To keep the satellite as light, simple and cheap as possible, no ADCS is mounted. The main question is then whether a completely arbitrary initial attitude and rotation will ensure that the sail can indeed complete its mission or whether there are some configurations to avoid. Within this work, the structural coupling is tested by means of a 3D model for the sail, to understand whether the modelling of the elasticity is necessary or negligible. To obtain significant results a 6-DoF model has been considered with drag, SRP, J2 and gravity gradient as perturbations. A grid search technique is used to investigate different initial values for the rotational behavior. There are three main results to be underlined from the outputs of the simulation: the non-negligible influence of the elastic behavior of the sail on the rotational motion of the satellite, the rotational rate evolution during de-orbit and the lifetime of the satellite that underlines the presence of a region of initial values that prevents the sail from re-entering in a small amount of time. Finally the problem of the self-shadowing, given the concave shape of the structure, is also addressed. Lastly, non-nominal deployment of the sail, resulting in particular shapes is also analysed to understand the influence of the shape on the satellite motion.","Gossamer; Elastic; Attitude and Orbital motion","en","master thesis","","","","","","","","","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:91f24566-9d4c-4a30-964b-a862487ada20","http://resolver.tudelft.nl/uuid:91f24566-9d4c-4a30-964b-a862487ada20","Reduced Separation during Final Approach: A procedural time based separation solution to optimize landing delivery","Driessen, C.L.V.","Curran, R. (mentor)","2016","","","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Aerospace Transport & Operations","",""
"uuid:ce0cffce-b345-433c-b0b1-359f16f05ad5","http://resolver.tudelft.nl/uuid:ce0cffce-b345-433c-b0b1-359f16f05ad5","Structural Optimization of Multi-Megawatt, Offshore Vertical Axis Wind Turbine Rotors: Identifying Structural Design Drivers and Scaling up of Vertical Axis Wind Turbine Rotors","Schelbergen, M.","van Bussel, G.J.W. (mentor); Simao Ferreira, C.J. (mentor); Bernhammer, L.O. (mentor)","2013","The knowledge about Vertical Axis Wind Turbines (VAWT) lags behind the knowledge about Horizontal AxisWind Turbines (HAWT), since most of the development of VAWT’s ceased after the 80’s. A lack of insight exists about how certain design parameters affect the rotor design of a modern VAWT. The objective of this thesis is to gain knowledge about the influence of the size (power capacity) of the turbine on the structural rotor performance of multi-megawatt VAWT’s by optimizing the rotor design. The influence of the size is expressed by scaling trends. The scope is limited to the structural design of the rotor blade and struts. The major loads on the rotor structure are aerodynamic, gravitational, and centrifugal loads. Fatigue, buckling, and resonance are the failure modes driving the design of the VAWT rotor. Modern manufacturing techniques of composite materials are believed to have a significant effect on the VAWT rotor design, since they offer more flexibility in the blade geometry. The mass increase of the blades is identified as a limiting factor for upscaling wind turbines. Gradient-based optimizations are performed to find the optimum 3-bladed H-rotor and Darrieus rotor designs for different rotor sizes and heights. The structural rotor performance is assessed by the ratio of the rotor mass over projected area. The laminate thicknesses and the shape of the rotor structure are varied in search of the optimum performance. A constant tip speed ratio and blade solidity is imposed on the optimization. Furthermore, constraints are imposed to prevent failure of the rotor structure. Optimizations of the VAWT rotor are performed for rotor sizes ranging from 3 MW to 20 MW. Rotor mass reductions for the carbon-fiber 20 MW H-VAWT and Darrieus VAWT of respectively 35% and 44% are obtained with respect to the fiberglass HAWT rotors. Despite this mass reduction, the material cost of the HAWT rotor will be significantly smaller. The optimized VAWT rotors are rough approximations of the best design solutions because of restrictions on the design space. In general, expanding the design space of the optimization yields better design solutions. In future VAWT rotor design optimization, the design space should allow for a variable diameter-to-height ratio of the rotor, since this parameter is driving the structural rotor performance.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","","",""
"uuid:e60e68fe-d1f6-458b-8a5a-d5036e32fb69","http://resolver.tudelft.nl/uuid:e60e68fe-d1f6-458b-8a5a-d5036e32fb69","Micro - Thruster Development: Propulsion System for the DelFFi Mission","Krusharev, I.","Zandbergen, B.T.C. (mentor)","2015","The format and size specifications of the CubeSat platform require highly miniaturized subsystems, one of the most challenging ones being the propulsion system. Up to date, according to the authors' knowledge, only two CubeSats have successfully operated a propulsion system in space: CanX-2 in 2008 and Defil-n3Xt in 2013. The importance of a miniaturized propulsion system becomes even more apparent when taken into consideration that most, if not all, of the CubeSats launched to date, due to budget constraints, have been piggybacking their launches into space and therefore they may end up in a non-optimal orbit. As a next step, a formation flying technology demonstration mission is planned by the Delft University of Technology (DelFFi), as part of the QB50 project. This thesis gives an outline of the present development status of micro-propulsion systems at Delft University of Technology. The main design driving criteria are provided by the DelFFi satellites requirements. Keeping in mind the educational environment in which the work is performed, safety drives the requirements: thus, propellants have to be non-toxic and easy to handle. Additionally, present requirements aim at a thrust level in the range of 1 to 10 [mN] and a total ?V of 15 [m/s] or more. Wet mass, when installed in triple-unit CubeSats, shall be less than 450 [g], and peak power consumption less than 10 [W]. A number of Commercial-Off-The-Shelf (COTS) systems have been investigated to find suitable candidates that fulfil these minimum requirements. However, it has been concluded that all presently available systems have low Technology-Readiness-Level (TRL) or their performance is out of the required range. It was thus necessary to start working at custom designed system. The design process and decisions made will be presented in this thesis. Furthermore for testing purposes also a test setup and an engineering model propulsion system was made. A general test program using LabVIEW was made that can automate the testing process of the thruster. The system was then tested and from the results, recommendations and conclusions were made for the next iteration of the thruster.","propulsion; CubeSat; DelFFi; satellite","en","master thesis","","","","","","","","2015-08-20","Aerospace Engineering","Space Engineering","","Space Systems Engineering","",""
"uuid:2475856b-edb2-4d28-b901-3dcfc1e993d5","http://resolver.tudelft.nl/uuid:2475856b-edb2-4d28-b901-3dcfc1e993d5","Aerocapture Guidance: Numerical and Artificial Intelligence Solutions","Zucchelli, E M.","Mooij, E. (mentor)","2016","","","en","master thesis","","","","","","","","2017-11-24","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:27e9dcc3-8422-485e-9926-1868f8900749","http://resolver.tudelft.nl/uuid:27e9dcc3-8422-485e-9926-1868f8900749","Fracture Toughness of Aerospace Structures: On the Use of Redundant Lattice Structures","de Boer, T.","Rans, C.D. (mentor)","2017","Both experimental and numerical studies have shown that the crack-bridging is one of the most significant mechanism contributing to the fracture toughness of natural materials like nacre and bone. This study aims to explore if additive manufactured lattice structures can be used to bridge fatigue cracks as well, thereby improving the fracture toughness of aerospace structures. By using enlarged Selective Laster Sintered unit cells, the response under mix-mode loading of five different unit cells was studied. Numerical models were used to give further understanding of the stiffness, fatigue response, and crack bridging capability of a redundant lattice core.","Additive Manufacturing; Fracture Toughness; Damage Tolerance; 3D Printing; Lattice Structures","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:fe4cb9c1-59a9-45a5-853d-1da2dccc74a1","http://resolver.tudelft.nl/uuid:fe4cb9c1-59a9-45a5-853d-1da2dccc74a1","Effect of Pop-Up Flights on Extended Arrival Manager","Vanwelsenaere, A.","Hoekstra, J.M. (mentor); Ellerbroek, J. (mentor)","2016","","","en","master thesis","","","","","","","","2021-09-30","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:d2f3a231-ac3c-4e91-ab74-64e93274b70f","http://resolver.tudelft.nl/uuid:d2f3a231-ac3c-4e91-ab74-64e93274b70f","Multidisciplinary Design Optimisation procedure for cooled turbine blades","Poli, R.","Gangoli Rao, A. (mentor); Pini, M. (mentor)","2016","","","en","master thesis","","","","","","","","2018-12-15","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Flight Performance and Propulsion","",""
"uuid:c5e0bc71-db3a-4619-a658-b0a773f45904","http://resolver.tudelft.nl/uuid:c5e0bc71-db3a-4619-a658-b0a773f45904","Exploration of optimal orbits in the strongly perturbed environment of the 2001 SN263 triple asteroid system","Obrecht, G.","Doornbos, E.N. (mentor); Cowan, K. (mentor)","2016","For the past 20 years, the small bodies of the solar system, such as asteroids and comets, have been increasingly gathering the interest of scientists and space agencies. The latter have been multiplying the number of space missions to study them. Brazil does not want to be left out and has been working on its own mission, ASTER, which has the particularity of having as a target a triple asteroid system. Although adding great scientific interest to the mission, this characteristic considerably complicates the mission design, by making the space probe move in a complex gravitational field and submitting it to very strong perturbations forces. Following the past researches on the ASTER mission, which mostly dealt with the characterisation of the 2001 SN263 asteroid system, this work focuses on the preliminary design of mission orbits suitable for the exploration of the asteroids. Two phases of the mission are considered: the arrival in the system, which requires a parking orbit; and the exploration phase. For the latter, two scenarios are studied: a parallel and a sequential observations of the system. To find the optimal orbits for each of these cases, a computer tool has been designed, which comprises an orbit integrator able to propagate the trajectory of a spacecraft within the asteroid system, and an optimiser which uses evolutionary algorithms to find optima from a 5-dimensional search space in a single- or multi-dimensional objective space, according to objective functions that can be chosen and adapted to match the case considered. The computer tool performs well for all cases, and allows to draw general conclusions on which kind of orbits to consider for the ASTER mission. The results show that the solar radiation pressure is by far the most problematic perturbation and is hence driving the properties of the solutions. Among all cases, many optima are terminator orbits, which are by nature strong against solar radiation perturbations. Moreover, orbits closer to the bodies are more stable, and any trajectory too distant from the bodies will be blown away. This work concludes on the suitability of the optimisation methods selected to the orbit design for this mission, although it is advised to still improve the software to model the dynamics of the system in a more detailed manner, and on recommendations for the ASTER mission. No satisfying parking orbit has been found and the relative strength of the solar radiation pressure implies that there does not exist orbits sufficiently remote from the bodies to serve as parking orbits. It is recommended to investigate other solutions with active orbit maintenance. As for the exploration phase, the sequential observation scheme shows its superiority. Satisfying observation orbits can be found about all three bodies, which is not the case for the parallel observation because of the zones of instability present in-between the bodies.","orbit; optimization; asteroids; triple asteroid; perturbations; four body problem; ASTER","en","master thesis","","","","","","","","","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:a7ee04a5-70e8-4bee-9e5d-bc68dcb9e893","http://resolver.tudelft.nl/uuid:a7ee04a5-70e8-4bee-9e5d-bc68dcb9e893","Design of Heat exchangers for Combined Brayton Cycle engines","Vidyarthi, K.","Rao, A.G. (mentor)","2017","","","en","master thesis","","","","","","","","2019-12-31","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:34dd3918-0d56-4f70-9fe0-f4338a784b2a","http://resolver.tudelft.nl/uuid:34dd3918-0d56-4f70-9fe0-f4338a784b2a","A Finite Element Method with Special Edge-Polynomials for Advection Problems","de Heij, B.","Gerritsma, M.I. (mentor)","2016","The field of Computational Fluid Dynamics (CFD) is constantly finding new ways to improve simulation results. One of the large challenges in CFD, is advection. Advection dominated flows are governed by hyperbolic equations, which pose severe stability issues. Stabilized methods usually add significant numerical diffusion, which alters the solution. Another issue are discontinuities in solutions, such as found in shock waves and acoustics. Besides solving these issues, conservative properties have to be satisfied at all costs. In order to further improve results, new methods are still developed today. The mathematical tools to do such developments are also further expanded. For instance, in the last decades the branch of differential geometry has steadily grown. This branch of mathematics can be extremely useful, since a clear distinction is made between geometric depend and geometric independent operators. These operators become more in use for numerical methods. Of all the available operators, the Lie derivative is important for advection. In junction with newly developed edge polynomials, a scheme for advection is created. The new edge polynomials are special, as these partly scale with a variable integrated over the cell and partly scale with the values on the cell boundaries. In order to do this, one polynomials integrates to 1 over the cell, while the other polynomials do not contribute, hence integrate to 0 over a cell. This gives several benefits. Conservation is clearly defined in the cells and not in points, hence conservation is locally defined. Also an extinction is made between conservative values and fluxes. One can also use the property of not contributing to conservation by correcting point values for stabilization or improvement of the solution. These polynomials are used within a Galerkin Finite Elements (FE) framework. Besides correction methods, upwind methods can be used as well. The approach is tested on several equation sets. On a simple linear advection problem, excellent results are found. Four test cases are tried, from a sine wave, two discontinuous functions and a hat function. With the proposed polynomials, the shapes are conserved extremely well, also in comparison to widely used schemes. On the inviscid Burgers’ equations, the stabilization methods become of importance. In the inviscid Burgers’ equation, initially smooth problems can become discontinuous. When a discontinuity forms, several issues can occur. For one, spurious oscillations can become apparent, or the velocity of the discontinuity can have errors. With several approaches, competitive results can be obtained. The discontinuity velocity is computed well, but spurious oscillation usually do occur. With several methods, the oscillations are suppressed. Not all approaches succeed in doing so. The third and final equation set to be tested, are the Euler equations. Although solutions can be found, all solutions contain errors. Several error sources are indicated, which should be addressed in further research. In comparison to a Monotonic Upstream-Centered Scheme for Conservation Laws (MUSCL) scheme, results need to be further improved to be on par. In conclusion, the suggested polynomials show potential. Several methods to improve solutions showed their usefulness. In linear advection, the new polynomials performed better compared to existing widely used methods. In non-linear advection, the results are on par with reference methods. For the Euler equations, further improvements are necessary. With further research, the benefits of such polynomials for numerical methods would become even more clear.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:38316ed7-e0f4-4695-8094-5eb484022df8","http://resolver.tudelft.nl/uuid:38316ed7-e0f4-4695-8094-5eb484022df8","Radius Bending: User Element Testing and Investigation on Effect of Stacking Sequence on Out-of-plane Failure","van der Meijs, J.J.","Abdalla, M.O. (mentor)","2016","A new doubly-curved shell element (ThickS4 element) is presented and tested for flat and singly curved configurations. The benchmark tests show good correlation for the ThickS4 element with the Abaqus S4 shell element and with 3D FEM for flat and highly curved configurations (R/t ≥ 4). For radius over thickness ratios smaller than 4 the element is not able to predict the correct behaviour. In order to give a good insight in the most critical radius over thickness ratios 1 ≤ R/t ≥ 8 a stacking sequence investigation has been done making use of the Abaqus C3D8 element. An L-shaped structure has been tested for different load combinations of in-plane, out-plane and opening-moment loading. From the investigation a clear overview of best stacking sequences for all the different loading combinations were presented as well as the ratio of ILNS versus ILSS. The results can further be used as guidelines for the initial design of composite C-spars and stringers.","Out-of-plane failure; Radius Bending; Doubly-Curved Shell Element; Interlaminar Stress; Stacking Sequence Investigation","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:90c8d527-7214-47ac-8a0b-0f03c40625cc","http://resolver.tudelft.nl/uuid:90c8d527-7214-47ac-8a0b-0f03c40625cc","Regenerative cooling analysis of oxygen/methane rocket engines","Denies, L.","Zandbergen, B.T.C. (mentor)","2015","Methane is a promising propellant for future liquid rocket engines. In the cooling channels of a regeneratively cooled engine, it would be close to the critical point. This results in drastic changes in the fluid properties, which makes cooling analysis a challenge. This thesis describes a two-pronged approach to tackle this problem. Simple and fast engineering tools allow for the development of insight in the design space using rapid iterations and parametric analyses. However, they are often rather inaccurate. In contrast, detailed multi-dimensional tools for numerical analysis are more accurate, but they require more computation time. Both approaches are developed for the analysis of regenerative cooling channels of oxygen/methane engines. Each approach uses complex but accurate models for the thermodynamic and transport properties of methane. OMECA (short for One-dimensional Methane Engine Cooling Analysis) is a one-dimensional tool that was developed in Python from scratch. This tool divides a nozzle into stations and analyses the one-dimensional thermal equilibrium at each station. It makes extensive use of semi-empirical equations to calculate the heat transfer at both the hot gas side and the coolant side. The tool is compared to a coupled multi-physics analysis tool, showing that the accuracy of the wall temperature is rather poor, with discrepancies of up to 150~K. Both at the hot gas and coolant side, large deviations are present. However, if the input heat flux is correct, OMECA predicts the coolant pressure drop and temperature rise with a 10% accuracy. To obtain a higher accuracy at the coolant side, the open-source CFD package OpenFOAM is adapted for analysis of supercritical methane. Of particular note is the custom library that interpolates the fluid property tables at runtime. The selected solver is applicable to steady-state compressible flows. The software is then systematically validated using three validation cases. With experimental validation data obtained through cooperation with CIRA, an accuracy of 15 K for the wall temperature prediction is demonstrated. The pressure drop is predicted within 10%. Traditionally, the launcher industry uses copper alloys as wall material in regeneratively cooled combustion chambers. They offer a high allowable temperature and high thermal conductivity, but are also heavy and expensive. Recently, several companies have demonstrated aluminium combustion chambers. Aluminium alloys have weight and cost advantages, but have lower allowable temperature and thermal conductivity. The developed tools for cooling analysis are therefore employed to compare aluminium and copper for a generic 10~kN combustion chamber. It is discovered that a thermal barrier coating must be employed to protect the hot gas side of an aluminium combustion chamber, otherwise regenerative cooling is not feasible. Even with such a coating, the pressure drop required to cool the coated aluminium chamber is three times higher than the pressure drop required for a copper chamber. A difference in pressure drop has effects on the vehicle level. A larger pressure drop in the cooling channel of a rocket engine necessitates a higher feed pressure. For a pressure fed engine, this means the tank must be stronger and heavier. It is found that even at modest fuel mass, the increase in tank mass is eight times as large as the decrease in engine mass offered by aluminium. This shows that using aluminium for the chamber wall is not advantageous with respect to copper for a pressure fed, regeneratively cooled, oxygen/methane rocket engine.","rocket engine; regenerative cooling; methane; CFD; OpenFOAM; aluminium; copper","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","Space Systems Engineering","",""
"uuid:580ebc9a-793b-49c5-8282-58987ac03432","http://resolver.tudelft.nl/uuid:580ebc9a-793b-49c5-8282-58987ac03432","Root Blade Load Estimation by Measurement Database for the Implementation in a SCADA System","Ochoa Algarin, C.A.","van Bussel, G.J.W. (mentor); Bierbooms, W.A.A.M. (mentor); Zaaijer, M.B. (mentor); Hofemann, C. (mentor)","2012","","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","Sustainable Energy Technology","",""
"uuid:56d99717-f15a-4ffa-b6a1-40c9ddc4eb93","http://resolver.tudelft.nl/uuid:56d99717-f15a-4ffa-b6a1-40c9ddc4eb93","A Dual-Beam Design Concept for the LOUPE Spectropolarimeter","Arts, M.L.J.","Kuiper, J.M. (mentor); Stam, D.M. (mentor); Snik, F. (mentor)","2015","In this thesis, a dual-beam design concept for the LOUPE (Lunar Observatory for Unresolved Polarimetry of Earth) spectropolarimeter is presented based on the work by Karalidi [2012] and Hoeijmakers [2013]. The mission statement of LOUPE is: LOUPE shall do spectropolarimetry of the Earth from the Moon in order to obtain reference data for exoplanet research. The requirements made by Karalidi [2012] and Hoeijmakers [2013] have been extended to a complete quantifyable requirements list from which the actual instrument can be designed. Trade-offs have been made for the choice of the technique to do spectropolarimetry and the polarizing beamsplitter that need to be implemented in LOUPE. The trade-off for the spectropolarimetric technique resulted in the choice of the spectral modulation technique in the form of the SPEX technique [Snik, 2009], because it allows for a compact design without moving components and is capable of doing instant polarization measurements. However, the SPEX technique does not allow for measuring circular polarization, meaning that LOUPE will only be capable of doing full linear spectropolarimetry. The trade-off for the polarizing beamsplitter resulted in the choice for the Savart plate as the beamsplitter, since a Savart plate allows for uniform splitting over the entire field of view. Using a ZEMAX model of LOUPE, it was shown that the aberrations caused by the Savart plate can be solved using a cylindrical lens. The dual-beam concept for LOUPE was determined in this thesis to be an f/4 system that has a field of view of 20 deg. The quarter-wave plate and multi-order-wave plate required for SPEX are located directly after the objective lens. The Savart plate is located in the image plane of a hexagonal microlens array (MLA). The MLA splits up the field of view in 44x35 pieces. Using clever stacking, the two modulated spectra for each MLA element are imaged on a 1024x1024 pixels detector. This results in 3x3 samples over the Earth, which allows for spatially resolving continents and oceans. A Matlab model for calculating the reflected solar flux levels on the Moon was made to analyse the obtainable polarization sensitivity per sample. This showed that with this concept a polarimetric sensitivity of 10^-4 can be achieved for terrestrial phase angles around 0 deg. A polarimetric sensitivity of 10^-3 can be achieved for terrestrial phase angles around 170 deg.","space; instrumentation; optics; spectropolarimetry; LOUPE; polarimetry; dual-beam; moon; Lunar; exoplanets; earth; optical","en","master thesis","","","","","","","","","Aerospace Engineering","Space Systems Engineering","","","",""
"uuid:a399cbeb-489f-4b8c-8873-63a059920a5e","http://resolver.tudelft.nl/uuid:a399cbeb-489f-4b8c-8873-63a059920a5e","Stress Analysis and Failure Prediction for Orthotropic Plates with Holes","Sevenois, R.D.B.","Koussios, S. (mentor)","2013","To allow structural designs with lower mass, it is necessary to have access to accurate failure prediction theories for composite plates with holes subjected to arbitrary loading conditions. For design purposes, however, the most accurate failure theories require a considerable amount of computational resources which is often not available. Additionally, current theories allowing less computational resources are unfortunately only valid for a specific load, material, hole or specimen size and their reliability is still questioned. The purpose of this work is to examine the existing methods to estimate stress and failure in composite plates with holes and subsequently join or modify them to provide an analytic tool for a quick and fairly accurate estimation of the static failure load. The plate is represented as a two-dimensional structure containing arbitrary loaded/unloaded holes and edge force boundary conditions. From a literature study, it is decided that an analytical model based on the method by Xiong and Poon [2] is used for the determination of the stress field. A new general failure criterion on the basis of Kweon [3] is constructed to determine failure. The stress and failure theories are implemented in a software package, verified by hand calculation and validated with finite element analysis and experimental data. The performance of the new failure theory was also compared to the performance of the in-house Point Stress Criterion at the company where the work was performed. The stress field methodology is able to accurately determine the stress field in two-dimensional plates with holes. The performance of the new failure criterion is better with respect to the in-house criterion and has a maximum discrepancy of +20% which is acceptable for design purposes. Unfortunatley, due to issues with the assumption of the stress boundary conditions for loaded holes, the method is restricted to laminates with a directionality lower than 1.13. Once these issues are resolved, the method will be generally applicable.","composite; stress; analytic; strength; static; lekhnitskii","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","Design and Production of Composite Structures","",""
"uuid:feac55be-3f8a-4cb0-bbec-4e3859fc64ce","http://resolver.tudelft.nl/uuid:feac55be-3f8a-4cb0-bbec-4e3859fc64ce","Training Effectiveness of Flight Simulators with Outside Visual Cues","Mendes, M.F.S.","Pool, D.M. (mentor); Mulder, M. (mentor); van Paassen, M.M. (mentor)","2016","","","en","master thesis","","","","","","","","2021-08-23","Aerospace Engineering","Control and Operations","","Control & Simulation","",""
"uuid:f72c5d11-d959-4778-831d-2abe07945398","http://resolver.tudelft.nl/uuid:f72c5d11-d959-4778-831d-2abe07945398","Visual Homing for Micro Aerial Vehicles using Scene Familiarity","Van Dalen, G.J.J.","De Croon, G.C.H.E. (mentor)","2016","Autonomous navigation is a major challenge in the development of MAVs. When an algorithm has to be efficient, insect intelligence can be a source of inspiration. An elementary navigation task is homing, which means autonomously returning to the initial location. A promising approach makes use of visual familiarity of a route to determine reference headings during homing. In this thesis an existing biological proof of concept based on desert ants is transferred to MAVs. Vision-in-the-loop experiments in different environments are performed, to investigate the viability of scene familiarity for visual navigation. Trained images are used to determine which control actions to take during homing. To determine familiarity, either a database of stored images is kept or an artificial neural network is used. Different image representations are compared in multiple simulated environments. The use of textons for determining familiarity gives the best performance, but HSV color histograms also perform well and are very efficient. It is concluded that to make this method competitive with other visual navigation approaches, route familiarity should be combined with other methods to improve robustness.","visual homing; MAV navigation; insect-inspired navigation; scene familiarity; autonomous flight","en","master thesis","","","","","","","","2018-05-30","Aerospace Engineering","Control and Simulation","","","",""
"uuid:902b96ba-753f-4c60-bed6-0d65bc47d4b3","http://resolver.tudelft.nl/uuid:902b96ba-753f-4c60-bed6-0d65bc47d4b3","Computational and experimental investigation on base drag reduction of a generic transportation system by guiding vanes","van Straaten, M.","Boermans, L.L.M. (mentor)","2007","Nowadays the amount of transport by road is still increasing, while the resources of fossil fuels are decreasing. Nearly 40% of the fuel consumption of a truck is due to aerodynamic drag, this means that aerodynamic improvements are certainly useful. A large aerodynamic drag component of a truck is due to suction at the base. Already in 1933 K. Frey did experiments to reduce the base drag of bluff bodies by the use of so called guiding vanes. He obtained drag reductions of nearly 50% by two dimensional experiments. In this projects it has been investigated by computational fluid dynamics and wind tunnel testing if it is possible to gain base drag reduction by guiding vanes on a three dimensional truck like wind tunnel model. A simplified and integrated tractor-trailer geometry has been used to examine the base drag mechanism and to implement the guiding vanes. Around this geometry a hybrid grid is created and the Reynolds Averaged Navier-Stokes (RANS) equations are used solve the ow pattern. They are most cost effective for this engineering research and practical to use.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a7dd75c9-b8e2-4169-90ee-7757cf39c0d4","http://resolver.tudelft.nl/uuid:a7dd75c9-b8e2-4169-90ee-7757cf39c0d4","Causes, Identification and Repair of loss of Common Ground in coordination in ATM (Air Traffic Management)","Kaur, M.","Sharpanskykh, O.A. (mentor)","2017","Over a century has passed since humans took to commercial flying. Traditional safety practices have worked well but the last decade has seen the need for an updated understanding of ATM safety. The modern safety views are complementary to the traditional ones but are also a new way of understanding and enabling safety practices. This master thesis report presents a comprehensive review of the sources chosen from literature to better understand how a complex sociotechnical system, such as ATM, would operate. Certain selected coordination aspects will be the focus of this master thesis and will be used to model and analyse an ATM case. The ultimate aim of this research project is to add to the growing body of knowledge in the field of ATM safety, to make flying increasingly safer and to enable a complex system to be resilient.","resilience; sociotechnical systems; atm; coordination; common ground; agent-based modelling; masa; abm; complex systems; cognition","en","master thesis","","","","","","","","","Aerospace Engineering","Air Transport Operations","","","",""
"uuid:a28c210a-5bdb-4de9-9259-5e634b1abf4e","http://resolver.tudelft.nl/uuid:a28c210a-5bdb-4de9-9259-5e634b1abf4e","Understanding and Improving Pressure Sensitive Paint based on luminescence decay","Mantel, J.","Scarano, F. (mentor)","2005","Pressure Sensitive Paint is a non-intrusive measurement technique, with which pressure distributions over surfaces can be measured. In wind tunnel application both accuracy and speed are of high importance. The PSP technique can be applied in two different approaches, the intensity based and the decay based method. The intensity based method is generally applied with satisfying performance. The decay based method is used less commonly, both speed and accuracy are considered insufficient for commercial wind tunnel use. Opposite from what today’s numbers indicate, the decay based systems are sometimes believed to be potentially much more effective. At DNW an experimental decay based system was available. The system is already used for over 10 years. Old studies indicated that measured data was not fully understood. The source for the disappointing results could not be identified. The goal of the present research was to gain further understanding of the system and to improve its capabilities where possible. To gain understanding the basic physics underlying the PSP operation were investigated more extensively. The expected decay behaviour is modelled in terms of a probability distribution. Relating observed decay to pressure is commonly done by curve fitting. The derived model for the decay however indicated that a different way of signal processing might give better results. By modelling the decay as a distribution, signal and noise are introduced inherently. Together with the new signal processing approach, the best possible accuracy or signal to noise ratio could be established. Speed of the system could not be increased, accuracy gained approximately a factor 2. From the derived model a prediction of the measurement could be made, in most cases the predicted accuracy was twice as good as what was obtained in practise. Differences between expected and obtained accuracy can be explained by the non ideal set-up and circumstances. The derived model matches measurement very well. Although the used setup can not be improved much, future decay based systems might outperform their intensity based counterparts.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a7a18912-312d-4c7b-bb74-e1dfb5feab7f","http://resolver.tudelft.nl/uuid:a7a18912-312d-4c7b-bb74-e1dfb5feab7f","Power-assisted dynamic soaring for a reconfigurable Unmanned Aerial Vehicle","Appeldoorn, B.","Visser, H.G. (mentor)","2016","","Dynamic Soaring; trajectory optimization; reconfigurable Unmanned Aerial Vehicle; Horizontal shear wind gradients; Energy extraction","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Aerospace Transport & Operations","",""
"uuid:d158a27e-b8a9-4677-9775-ed47f01ebfaf","http://resolver.tudelft.nl/uuid:d158a27e-b8a9-4677-9775-ed47f01ebfaf","Spatially mass-, kinetic energy- and helicity-preserving mimetic discretization of 3D incompressible Euler flows","Zhang, Y.","Gerritsma, M. (mentor)","2016","Based on the recently developed mimetic spectral element method, we propose an effective numerical scheme for solving three-dimensional periodic incompressible Euler flows, which spatially preserves mass, kinetic energy and helicity. Preserving multiple integral invariants numerically will significantly contribute to the stability and accuracy of the numerical scheme. We start from the introduction of differential geometry and algebraic topology with which we then set up the mimetic spectral element method (the mimetic framework). With the mimetic spectral element method, physical variables can be expressed in more physical forms and the discretization error will be eliminated as much as possible. After that, we turn to Euler equations. We first rewrite Euler equations as inner oriented Euler equations and outer oriented Euler equations in terms of differential differential forms. Meanwhile the conservation laws of mass, kinetic energy and helicity based on these new forms of Euler equations at the continuous level are proven. Then, according to expressions of kinetic energy and helicity in the mimetic framework, we convert the inner oriented and outer oriented Euler equations into two weak forms and then spatially discretize them using the mimetic spectral element method in a unit 3-cube ([-1,1]^{3}) domain equipped with a cell complex given by the Gauss-Lobatto-Legendre grid. Afterwards, interactions between the two spatially discretized weak forms and discretizations of time derivative terms are constructed, which eventually gives rise to a solvable, mass, kinetic energy and helicity spatially preserved, fully discretized system. The scheme then is tested with a periodic flow. In summary, the mass conservation is automatically achieved by taking the divergence free flow condition exactly into account. In addition, with proper discretization of the momentum equation and vorticity equation both kinetic energy and helicity are spatially preserved at the discretization level.","mimetic; Euler equations; conservation; discretization; mass; kinetic energy; helicity","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics and Wind Energy","","Aerodynamics","",""
"uuid:e8515fbc-c44d-47a2-b79c-fbd6fb92b924","http://resolver.tudelft.nl/uuid:e8515fbc-c44d-47a2-b79c-fbd6fb92b924","Incremental Nonlinear Flight Control for Fixed-Wing Aircraft","van Ekeren, W.","Chu, Q.P. (mentor); Looye, G. (mentor)","2016","In the context of fault-tolerant flight control (FTFC), various types of incremental nonlinear control methods have been previously proposed that should overcome important challenges that are imposed by the use of nonlinear, model-based flight control systems. This work presents an analysis, design and implementation of promising incremental nonlinear dynamic inversion (INDI) and incremental backstepping (IBS) control laws for a fixed-wing aircraft. Flight tests on an Unmanned Aerial Vehicle (UAV) validate the control design and confirm many of the advantages of these methods. A summary of the contribution is split up into three parts. First, an analysis is done on the performance of incremental nonlinear dynamic inversion for angular rate control. Incremental nonlinear dynamic inversion is shown to see great similarities with ordinary PI(D) control. When not including the actuators of the system, the gains of an incremental PI controller can be derived from the INDI control law, yielding an equivalent control law. In a similar manner, similarities can be derived between INDI and a non-incremental PI control law that does not need a feedback of the state derivative. Simulations on a model of the fixed-wing UAV support the findings. Besides a comparison with PI control, the validity of the assumptions of incremental methods are assessed for the case of angular rate control for fixed-wing aircraft. Steady state tracking errors in the inner control loop are caused by the assumption that the control-independent part of the acceleration does not change significantly. The steady state errors are directly related to the so-called increment delay, the effective time over which an incremental control action is given. Hence, the negative effect of neglecting the system dynamics increments can be mitigated by using faster actuators or by decreasing the acceleration measurement delay. Secondly, integrated controller designs are presented for the attitude control of the aircraft. Control laws are designed for both the Euler attitude angles, as well as for the aerodynamic attitude. This is done using multi-loop nonlinear dynamic inversion and the Lyapunov-based backstepping procedure, yielding a multi-loop INDI and an IBS controller. Supported with model validation using flight data from open-loop experiments, the robustness of the controllers is demonstrated. Furthermore, the IBS aerodynamic attitude controller has been extended with an extra incremental backstepping loop to control the flight path angle and the airspeed. Finally, flight tests are performed that validate the controller designs. Mainly qualitative conclusions can be drawn from the flight results. The INDI controller that controls the Euler attitude angles has been successfully tested in nominal flight. Simulated controller responses match closely with flight measurements. Also, a manually controlled flight with this INDI control law as augmented control has been performed. In the longest experiment, lasting 241 seconds, the longitudinal and lateral mode were excited with pitch angles of ±22 deg and roll angles of ±50 deg. The IBS controller that controls the aerodynamic attitude was tested in both longitudinal and lateral mode, during separate maneuvers. Although results show a stable response to angle of attack commands, the lack of a good estimate of the angle of attack limits the applicability. The lateral mode of the aircraft was only tested with conservative, non-nominal gains. The results correspond to the expected response, but subsequent tests must be performed for a full validation.","","en","master thesis","","","","","","","","2018-12-15","Aerospace Engineering","Control & Operations","","","",""
"uuid:004fae47-161e-47e5-9df6-f030a732a08f","http://resolver.tudelft.nl/uuid:004fae47-161e-47e5-9df6-f030a732a08f","Complexity Metric Comparison Study for Controller Workload Prediction in 4D Trajectory Management Environments","Toy, J.J.N.T.","Borst, C. (mentor); Klomp, R.E. (mentor); Mulder, M. (mentor); Paassen, M.M. (mentor)","2015","The future of air traffic management moving to 4D trajectory-based operations will require the development of new airspace sectors to increase aircraft capacity and advanced 'human-centered' decision support tools for future air traffic controllers. To evaluate and aid in the design of future air traffic management systems, complexity metrics would help to speed up the development of advanced safe air traffic management systems. Although an airspace sector may look 'complex' with many aircraft, this does not equate to it actually being complex with the right tool. The complexity of a sector or traffic scenarios depends on a large number of factors, irrelevant of the tool. Previous studies with well developed state-based complexity metrics focused on air traffic controllers safely controlling traffic of today, with a 'hands-on' approach. One recent metric based on trajectory-based management could prove to help predict controller workload. The goal of this study has been to empirically investigate if a complexity metric can predict human controller workload in future 4D trajectory management environments. For this purpose a previously developed 4D management tool had been used to support a controller in an envisioned future large airspace sector with varying traffic structures and perturbation levels. A well developed state-based complexity metric was compared against a recent trajectory-based complexity metric by the results of the reported workload experienced. Results of a human-in-the-loop experiment indicate that the trajectory-based complexity metric looks promising to workload predictions in 4D trajectory management environments.","workload; inherent complexity; 4D trajectories; air traffic management; human-machine interaction","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Operations","","Control and Simulation","",""
"uuid:e9680a79-e62e-47d6-9637-f45c5ef4ecc3","http://resolver.tudelft.nl/uuid:e9680a79-e62e-47d6-9637-f45c5ef4ecc3","The Degradation of Carbon Fibre-Reinforced Epoxy Composites under Fusion Bonding Conditions","van der Ree, M.","Sinke, J. (mentor)","2016","In the aircraft industry there is an increasing need for cost-effective assembly methods for dissimilar thermoplastic/thermosetting composites. Fusion bonding provides a good alternative to mechanical fastening, and may be applied to thermosetting composites by using a thermoplastic interlayer. The research project ‘HyPoComp’ at Delft University of Technology aims to develop a resistance welding process for joining CF/epoxy and CF/PEEK. A satisfactory joint strength can be achieved, but there are concerns about the high temperature introduced into the thermosetting substrate during the joining process. This thesis investigates the thermal degradation of CF/epoxy composites under short-term, high temperature thermal loads.","thermal degradation; thermoset; composite; resistance welding; fusion bonding","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:f874600f-7cf3-468e-b6e7-fdadc3441077","http://resolver.tudelft.nl/uuid:f874600f-7cf3-468e-b6e7-fdadc3441077","An experimental and computational investigation of a diffuser augmented wind turbine: With an application of vortex generators on the diffuser trailing edge","Ten Hoopen, P.D.C.","Van der Heiden, K. (mentor); Van Bussel, G.J.W. (mentor)","2009","The Diffuser Augmented Wind Turbine (DAWT) has been studied periodically over the last five decades. It has already been established by the scientific community that the DAWT is superior to conventional bare wind turbines. In spite of this, the DAWT has not gained popularity worldwide due to high manufacturing cost of the diffuser. There are two possibilities to make a DAWT more lucrative; lowering the manufacturing cost or increasing the performance. The present thesis is concerned with the second approach and considers the hypothesis that the generating power of a DAWT can be increased by turbulent mixing of the wake and free stream flow. This mechanism should decrease the diffuser’s exit pressure and consequently increase the mass flow and power. In the present investigation this turbulent mixing is established by placing vortex generators on the diffuser trailing edge. The hypothesis was tested through a series of full scale wind tunnel experiments. The experiments were conducted in the open jet facility of Delft University of Technology in collaboration with Donqi Urban Windmills. It was found that the application of vortex generators on the diffuser trailing edge lead to an increase in power of 9%. Furthermore, in the pursuit of a better understanding of the flow behavior, an inviscid singularity model was formulated. The model uses a surface vorticity technique to simulate the behavior of the diffuser, supplemented with a lifting line approach to model the rotor. It was found that the inviscid model did capture the behavior of the DAWT reasonably well, although when compared to the measurement results it was observed tobe overly optimistic.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","AEWE - Windenergy","","","",""
"uuid:24c0bfab-3243-4ffa-9c96-10a4721fb23a","http://resolver.tudelft.nl/uuid:24c0bfab-3243-4ffa-9c96-10a4721fb23a","Advanced Flight Control Design and Evaluation: An application of time delayed Incremental Backstepping","Koschorke, J.F.R.","Falkena, W. (mentor); Chu, Q.P. (mentor); Van Kampen, E. (mentor)","2012","The sensor-based approach of Incremental Backstepping is applied to flight control law design in this research project. It allows the usage of the same control law on different types of aircraft without the need for redesign. Apart from full state availability, the derivation of Incremental Backstepping assumes instantaneous control action. Due to actuator lags and delays, the implementation of control commands cannot necessarily be considered instantaneous. This mitigates the stability guarantee provided by Lyapunov theory. Therefore, a novel technique to estimate the time delay margins of the Incremental Backstepping controlled systems is proposed in the thesis. This provides an important stability measure for possible certification and widens the application range of Incremental Backstepping. This simple, yet effective, Lyapunov-based control technique shows positive robustness properties with respect to model uncertainties, unknown parameters, external disturbances and time delay effects. It is applied to the DA 42 aircraft as a (pilot-in-the-loop) rate controller in the scope of this thesis. The implementation requires measurements of the aircrafts angular accelerations and control surface deflections. If the latter is not available, it is shown that filters can still be used in the control system. However, the usage of filters mitigates the highly favorable robustness properties of the closed-loop system. Moreover, a controller evaluation strategy is proposed. It rates the performance and stability properties of the Incremental Backstepping controlled system in terms of the flight control system requirements. Evaluation of the Incremental Backstepping controller shows allowable input multiplicative uncertainties of up to 40% of the nominal value at the worst-case excitation frequency for a controller update rate of 100Hz. When no reference shaping is applied, the handling qualities of the incremental rate controller show to be less desirable than that of a conventional linear controller designed specifically for the DA 42. However, it is possible to improve handling characteristics by reference shaping. Furthermore, the handling characteristics of the incremental controller remain fairly constant along the flight envelope and in adverse flight conditions.","Incremental Backstepping; Time delay; Lyapunov-based control; Fly-By-Wire; Diamond DA 42; Nonlinear; Sensor-based control; SAFAR; Pilot-in-the-loop; Aircraft rate control; Flight control evaluation; SSV","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Operations (C&O) - Control and Simulation Division (C&S)","","Guidance, Control & Navigation","",""
"uuid:698e7ac8-23ac-4c13-831b-f9125838ff1c","http://resolver.tudelft.nl/uuid:698e7ac8-23ac-4c13-831b-f9125838ff1c","Multiple-Phase Trajectory Optimization for Formation Flight in Civil Aviation","van Hellenberg Hubar, M.E.G.","Visser, H.G. (mentor)","2016","A tool is developed that is able to optimize the trajectories of multiple aircraft that fly in formation in order to obtain the minimum total fuel consumption. Several experiments are conducted to investigate the benefits of formation flight for commercial aircraft. Finally, also the influences of wind and delay on the trajectories of the aircraft that join in the formation are examined","formation flight; civil aviation; GPOPS; multiple-phases; multiple aircraft; optimization; trajectory optimization; minimum fuel burn; minimum Direct Operating costs; multiple-phase trajectory optimization","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Operations","","Aerospace Transport & Operations","",""
"uuid:9953c8bc-d03b-4ada-bc6d-d76282317ded","http://resolver.tudelft.nl/uuid:9953c8bc-d03b-4ada-bc6d-d76282317ded","Supersonic Flight Characteristics of a Winged Re-Entry Vehicle","Annega, G.","Mooij, E. (mentor); Sudmeijer, K.J. (mentor)","2017","Spaceplane designers need to be able to rapidly obtain estimations of aerodynamic and stability parameters throughout the re-entry flight. This aids with design changes and trade-offs regarding the stability characteristics of the design. This software was developed with a focus on stability analysis in the Terminal Area Energy Management phase (TAEM), the penultimate phase of the return to Earth. For the HORUS spaceplane, a design study by MBB in the 1980s, the stability coefficients are known down to a Mach number of 1.2 and the dynamic stability characteristics down to a Mach number of 2.5. In this thesis a method is developed to calculate the aerodynamic forces and moments on a spaceplane. This method consists of two parts, an inviscid Euler code for the flow field away from the spaceplane and a viscous boundary layer code for the flow at the surface. The boundary layer code is based on the axisymmetric analogue, which uses a coordinate to transform a complex body into a series of axisymmetric bodies as long as the cross-flow between the streamlines is negligible. Using the Mangler transformation, these axisymmetric bodies can be transformed to flat plates, upon which momentum thickness and skin friction equations can be used. The inviscid Euler code calculates the pressure forces and moments, while the viscous boundary layer code calculates the forces and moments due to friction drag. The combined pressure (inviscid) and friction (viscous) forces and moments on the HORUS are then used for stability analysis at Mach numbers of 2, 1.2 and 0.8, adding to the existing data set. The stability analysis focuses on the stability coefficients (static stability) and motion characteristics (dynamic stability) around the trim condition at the aforementioned Mach numbers. For the dynamic stability an eigenvalue and eigenvector analysis is performed to investigate which motions are present in the lower Mach regimes, whether these motions are stable and how the vehicle behaves during these motions. It is shown that the forces on the vehicle are simulated very well using this methods, as well as the longitudinal pitch moments. For the moments and derivatives regarding roll and yaw the simulated values differ significantly from the reference values. The simulations also show the large influence on the center of mass position on the stability of the HORUS, slight changes can turn an unstable motion in a stable motion and vice versa. Finally, the simulations show that the HORUS generally becomes more stable at lower Mach numbers, which indicates that the TAEM is not the critical phase regarding design for a stable spaceplane.","","en","master thesis","","","","","","","","","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:2dbcdb3d-0606-4707-b7ba-6e7ceafd549b","http://resolver.tudelft.nl/uuid:2dbcdb3d-0606-4707-b7ba-6e7ceafd549b","Aircraft Fuselage Design Study: Parametric Modeling, Structural Analysis, Material Evaluation and Optimization for Aircraft Fuselage","Şen, I.","Alderliesten, R.C. (mentor); Benedictus, R. (mentor); Rans, C.D. (mentor); Neelis, B.M. (mentor)","2010","The strong search for lightweight materials has become a trend in the aerospace industry. Aircraft manufacturers are responding to this trend and new aerospace materials are introduced to build lighter aircrafts. However material manufacturers, like Tata Steel, are unfamiliar with the determination of running loads and the behavior of materials in fuselage structures. Therefore an evaluation tool is needed for determining the running loads and evaluating the performance of new materials. This will give material manufacturers better insight in what properties and performance are specifically needed for materials in aircraft structures. The goal of this project is to develop an analytic design, analysis and evaluation tool for both metal and composite fuselage configurations in Visual Basic Application in order to gain insight into the structural performance of these material classes and to estimate the weight and required structural dimensions for both aluminum and composite fuselages. The fuselage geometry is setup parametrical and modeled as a simplified tube with variable crosssection without cut-outs and wing box, and it is divided in bays and skin panels. By modeling the aerodynamic-, gravity-, ground reaction forces and internal pressure a free body diagram and force/moment distribution is created for several flight and ground load cases, like 1G flight, lateral gust or landing load cases. The critical load cases are used for analysis. The running loads, like bending stress, longitudinal stress, circumferential stress and shear stress are calculated for the entire aircraft fuselage. A clear load pattern is created in order to evaluate the materials. The materials are evaluated for strength, stability and several other failure modes, like fatigue and crack growth. The skin panels are optimized for these evaluation methodologies and after doing so a minimum fuselage weight is obtained for conventional aircraft configurations. The Airbus A320 is taken as reference aircraft and the running loads and optimization results of the model are validated with this aircraft. The model proved to be valid and is therefore considered suitable to be used as an analysis and evaluation tool. The final stage of the project involved an initial assessment of aluminum and composite as structural material.","aircraft design; fuselage design; parametric modeling; structural analysis; optimization; aluminum; Ilhan Sen","en","master thesis","","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:e4f53a94-348b-4cba-8496-79cf1b454940","http://resolver.tudelft.nl/uuid:e4f53a94-348b-4cba-8496-79cf1b454940","Development of a low-cost Fiber Metal Laminate with a focus on low-velocity impacts","Simoiu, K.M.","Poulis, J.A. (mentor); Gransden, D.I. (mentor)","2016","The development of Fiber Metal Laminates (FMLs) allowed designing lightweight structures that are more impact and fatigue resistant than the individual materials they are made of. However, high production costs restrict the use of FMLs to the aeronautical industry. A reduction in production costs can pave the way for applications in other fields as well. FMLs made of low-cost thermoplastic (TP) prepregs were produced with a heated press in order to reduce production costs. PA6 and PC in combination with an E-glass fabric were chosen for the composite layers and Al-2024-T3 for the aluminum layers. Al-2024-T3 was artificially aged to study the influence of temperature and time on the tensile properties of the alloy. Interlaminar shear strength tests were used to assess qualitatively the influence of process temperature, pressure, time and fabric type on the interface strength. This preliminary study demonstrated that aluminum underwent precipitation hardening. In addition, the combination of composite consolidation and aluminum-composite bonding in one production step (Production 1) resulted in FMLs with large areas of dry fibers. As a consequence, a second production was proposed (Production 2), in which the composite is first produced in the press and then adhesively bonded to the aluminum layers with an adhesive hot melt. Following this experimental study, the aluminum-composite interface strength of the TP FMLs was assessed quantitatively. The assessment was based on single cantilever beam tests, which were used to determine the interfacial fracture energy. Fracture energies in the range of 2500-3200 J/m2 were observed in the experiments. These relatively high values could be explained by plastic deformation of the adhesive at the interface, which failed in a cohesive manner. Low-velocity impact tests were performed with a drop-tower. Samples from Production 1 showed a stiffer response and less energy absorption through plastic deformation of the aluminum layers compared to specimens from Production 2. This behavior was attributed to precipitation hardening of the aluminum layers of Production 2. In addition, a smaller damage area was observed for Production 2 samples, which still had a 60% larger damaged area compared to GLARE. However, a PA6 FML that absorbed the same amount of impact energy for the same damage area as a GLARE reference laminate would cost around 23% less. It shows that TP FMLs have the potential to be a low-cost alternative to impact resistant, commercial FMLs for low-velocity impacts.","","en","master thesis","","","","","","","","","Aerospace Engineering","Structures & Materials","","","",""
"uuid:d47d7ded-ff0c-442e-a356-d31d8013b791","http://resolver.tudelft.nl/uuid:d47d7ded-ff0c-442e-a356-d31d8013b791","Influence of stiffeners on a variable stiffness laminate optimisation","Laan, R.P.J.","Abdalla, M.M. (mentor)","2016","Engineers are still looking for ways to improve the performance of materials used in aircraft. A major step was going from metal parts to laminates in order to save weight significantly. Those laminates existed of fibres with a constant orientation, and became laminates with changing fibre directions. Variable stiffness laminates (VSL) are used for its possibility of exploiting the anisotropic properties of composites. In order to improve the buckling load of a panel, VSL are used. Those laminates steer the loads through the laminate. This is beneficial for maximising the buckling load of a panel. An optimiser is built by the Delft University of Technology to optimise VSL by changing its fibre orientations throughout the entire panel. A manufacturing constraint is added to the optimiser to prevent the fibre paths to have a turn radius of smaller than 0.333[m]. Plate designs with fibres paths having a smaller turn radius than this constraint, are assumed to be unmanufacturable. The software optimises fibre paths of VSL against buckling and keeps the stiffness of the entire plate equal or higher than the quasi isotropic design. Since the aircraft of nowadays are stiffener dominated, an extra functionality is added to the optimiser. The optimiser is further developed to be capable of optimising stiffened plates. Stiffeners are taken into account during the optimisation. Extra functionalities such as integrated stiffeners are introduced. These are stiffeners sharing layers with the plate. The extended optimiser is verified by comparing the internal loads from five cases with the values calculated with ABAQUS. After having the optimiser verified, it is used to calculate results for twelve different cases. Those cases range from square unstiffened plates to rectangular plates with two stiffeners. The results show the influence of stiffeners on the optimised panel with changed fibre paths. Those cases are compared to the plate designs with the stiffeners excluded from optimisation. Performance increases of up to 174% are obtained for balanced symmetric laminates. The results show clearly that when stiffeners are added to a panel, the area in-between the stiffeners can be treated as a simply supported plate. Integrated stiffeners also show a buckling load increase of 113% with respect to the quasi isotropic case. The fibres of the buckling optimised plates show a relating behaviour. Fibre orientations going towards [45,-45] are present in buckling critical areas. Near stiffeners and near edges, [0,0] areas are present in order to introduce the load through the structure. A relation is found between having more [0,0] orientations in the inner plies of the laminate and significantly more [45,-45] orientations at the outer plies of the laminate. The outer plies are more critical for buckling, which requires more fibres being close to a [45,-45] in order to higher the buckling load. The inner areas are less vulnerable for buckling, which creates the opportunity of creating stiffness in the inside of the laminate.","optimisation; stiffener; variable stiffness laminate; fibre steering; composite; laminate","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Computational Mechanics","","","",""
"uuid:ceadc7fb-b86f-4755-a465-a30550b15dcb","http://resolver.tudelft.nl/uuid:ceadc7fb-b86f-4755-a465-a30550b15dcb","Development and Reuse of Engineering Automation","Dewitte, P.J.A.R.","Van den Berg, T. (mentor)","2014","Increasingly engineers in, for example, Aerospace Engineering create software to support their daily engineering activities. This is referred to as Engineering Automation. A prime example of Engineering Automation is Knowledge Based Engineering. It is desirable to reuse and share this software, rather than to discard it soon after its creation. Unfortunately, the overall level of sharing and reuse in daily engineering automation practice is currently low. Producing reusable applications proves to be difficult for engineering automation developers. An initial study comprising a literature review and expert interviews showed that the two main issues are the understandability and validity of the software and documentation. The study also provided insight in the current Engineering Automation culture. The most important aspect identified is the lack of incentives for software activities other than coding itself. Based on the initial study, a software design tool based on incremental code and design documentation generation was selected as the most suitable approach to start tackling the issues identified. To contribute to understandability and validity, and ultimately reuse, the tool aims to encourage the creation of accurate design documentation and to encourage the creation of that documentation before implementing the corresponding code. Creating a design beforehand encourages a well thought and understandable application structure, yet this is rarely done in an Engineering Automation context. The approach was implemented for a specific community of Engineering Automation developers, namely users of the GenDL software framework. The resulting tool, GenDL Designer, features a simplified version of the Unified Modeling Language, continuous consistency checking with the code and support for incremental resolution of inconsistencies, e.g. by generating code skeleton fragments or by proposing design diagram modifications. GenDL Designer was developed with Engineering Automation developers in mind and therefore differs significantly from general software engineering tools with similar objectives. To address the potential and feasibility of incremental code and design documentation generation for engineering automation development, a large-scale academic experiment with GenDL Designer is planned in spring 2014. In anticipation of that, trial runs were held, which only allow for preliminary conclusions. GenDL Designer seems to encourage the creation of accurate design documentation and seems to encourage designing before implementing. The principle of incremental code and design documentation generation appears to have the potential to improve the understandability of applications, the validity of their documentation and even the validity of the code itself, due to the improved transparency that uncovers defects. Finally, introducing incremental code and design documentation generation in an engineering automation context appears to be feasible, but some potential users will not be convinced with a short introduction alone. These promising but preliminary findings will hopefully be confirmed with the large scale academic experiment and later on with experiments in industry.","Engineering Automation; Model-Based System Engineering; Code generation; Professional End-User Development; Software Reuse","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","System Engineering and Aircraft Design","",""
"uuid:6210b7b5-8599-4ed6-bf3b-738f9a8d0f97","http://resolver.tudelft.nl/uuid:6210b7b5-8599-4ed6-bf3b-738f9a8d0f97","Automatic detection of buried channel deposits using high resolution laser altimetry data (FLI-MAP)","Possel, B.M.J.","Simons, D.G. (mentor); Lindenbergh, R.C. (mentor); Storms, J.E.A. (mentor)","2010","The formation of the current Rhine-Meuse delta has mainly taken place during the Holocene (the last 12,000 years). This period is characterised by avulsions that lead to sudden shifts in the location of river channels. The channel deposits left behind by abandoned rivers are often distinct sandy layers in the shallow sub-surface, called buried channel deposits. Knowledge of the location of buried channel deposits is interesting from a historical point of view and is essential for planning, constructing and maintaining structures that intersect these channels. Traditionally, buried channel deposits are traced using labour intensive soil drillings and visual interpretation. However, some buried channel deposits can also be detected by using local elevation differences (1 - 2 m) caused by differential compaction. Automating the detection process and using Digital Elevation Models could result in faster processing and a higher detailed, more objective map. This leads to the following research question: is it possible to automatically derive a detailed map of buried channel deposits from high resolution laser altimetry data? The dataset used for this purpose is a rasterized elevation model measured by the FLI-MAP system with the same specifications as AHN-2. First, two filtering methods are applied to remove infrastructure and other objects using existing topographical data (GBKN) and terrain characteristics (variability and density). If these objects are not removed they cause errors in the final result. In the detection procedure four structural attributes are calculated using the elevation dataset: slope, curvature, relative elevation (TPI) and smoothed TPI. This is done to use as much of the available information in the detection procedure. With these attributes a multi-band image is formed. Classification is then performed using a Maximum Likelihood classifier were each point is assigned to a predefined class. A majority filter is applied on the result and empty areas are interpolated using a conditional dilation to get a full coverage of the area. Processing speed is increased by downsampling datapatches that are used for computational intensive algorithms. Additional automation of the detection process is performed by developing a method to resolve edge effects on tiled datasets. Validation is performed by comparing the detection result to two independent datasets. A palaeogeographic map is used to make a numerical and visual comparison. An analysis using shallow drilling measurements is performed to determine the depth of the detected sand layers. The results indicate that buried channel deposits (between 4,620 and 1,700 years old) can be mapped roughly in a fully automatic way. The probability that these channels are within a certain depth can be calculated. Validation shows that this new method is strongly hampered due to human intervention in the landscape. Further research is recommended to improve the filtering and detection method.","buried channel deposits; FLI-MAP; airborne laser scanning; Rhine-Meuse delta","en","master thesis","","","","","","","","2010-02-19","Aerospace Engineering","Mathematical Geodesy and Positioning","","","",""
"uuid:c911a052-4c39-4d5e-a929-376769146fee","http://resolver.tudelft.nl/uuid:c911a052-4c39-4d5e-a929-376769146fee","Design concepts for offshore wind turbines: a technical and economical study on the trade between stall and pitch controlled systems","Jaimes, O.G.","van Bussel, G.J.W. (mentor); Zaaijer, M.B. (mentor); van Rooij, R.P.J.O.M. (mentor); Kling, W.L. (mentor)","2010","Maintenance of offshore wind turbines is much more expensive than that of onshore machines. Several suggestions have been made in this respect to reduce operation and maintenance costs by employing simpler turbine concepts with higher reliability. Particularly, stall-controlled machines have been suggested as robust and reliable options that could lower operation and maintenance costs, due to the lack of a pitch mechanism and its control system and because of the lower failure rates they seem to have. This turbine concept, however, trades-off turbine performance against operation and maintenance costs. The focus of this thesis is to determine the possible gains regarding operation and maintenance and the losses in power performance resulting from changing turbine concept from pitch to stall control. To do so a design assessment of a baseline, pitchcontrolled turbine and an alternative, stall-controlled one is carried out. The turbines are designed for an IEC class IA and aimed for a specific location in the North Sea. The designs are then compared and evaluated according to their technical and economical performance. Qualitative as well as quantitative comparisons are pursued to get insight in the advantages and disadvantages of each concept when intended for offshore locations. The energy yield, availability, operation and maintenance and levelised production costs associated to each turbine design are estimated to identify which turbine option could lead to the most benefits in the case of an offshore wind farm. From the analysis made it can be observed that the use of a stall-controlled scheme does contribute in reducing the operation and maintenance expenses of an offshore wind farm project. The loss in performance, however, surpasses the gains in maintenance and availability attained.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","Sustainable Energy Technology","",""
"uuid:dec77b3c-d36a-4142-a6fd-f7487c842f42","http://resolver.tudelft.nl/uuid:dec77b3c-d36a-4142-a6fd-f7487c842f42","Influence of Nonlinear Irregular Wave Modeling on the Dynamic Response of an Offshore Wind Turbine","van der Meulen, M.B.","van Bussel, G.J.W. (mentor); Huijsmans, R.H.M. (mentor); Bierbooms, W.A.A.M. (mentor)","2012","In the past decades, offshore wind energy has emerged as one of the most promising renewable alternatives to the traditional fossil sources of energy. Although the ocean has a vast potential, with higher wind speeds and lower turbulence levels than onshore, the required marine foundations make the realization of an offshore wind farm expensive. Partly, the high cost of a foundation is caused by the safety factor that is used to compensate for uncertainties in modeling the forces acting on the offshore wind turbine.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f2dd2a05-f7d7-4b22-92c6-cc04e2499780","http://resolver.tudelft.nl/uuid:f2dd2a05-f7d7-4b22-92c6-cc04e2499780","Development & assessment of equipment and procedure for continuous ultrasonic welding of thermoplastic composites","Van Beurden, M.Q.C.","Fernandez Villegas, I. (mentor); Palardy, G. (mentor)","2015","Ultrasonic welding (USW) is a technique used to bond materials together by heating the bonding surfaces with ultrasound. Its main advantage is the high processing speed, which is in the order of seconds. However, application of this technique with thermoplastic composite (TPC) materials is still limited. One of the areas in which almost no research has been done is continuous ultrasonic welding of TPCs. This MSc thesis therefore explores some possibilities on a continuous variant of the ultrasonic welding process, applicable to TPCs. To do this, a machine was designed and developed which has a single, horizontally moving axis. This machine is able to weld in a straight line, complying to any thickness changes in the material. The design has been tested by comparing welds made with it with welds made on a conventional machine. The machine works correctly, but the frame has to be made stiffer, for which recommendations are made. Research was conducted into multiple-pass welding as well, as it is a potential solution for some of the problems sequential ultrasonic welding is facing. This research consisted of welding lap shear specimens in two separate passes, and comparing the produced weld with a reference (single-pass) weld. It is shown that the welding processes and welds are very similar, which makes current knowledge on ultrasonic welding applicable to multiple-pass welding.","continuous ultrasonic welding; thermoplastic composite; multiple pass welding; machine design; lap shear strength","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","Structural Integrity & Composites","","51.990656, 4.3766204"
"uuid:3ce05448-84b7-4dc7-ad2e-2883b423a337","http://resolver.tudelft.nl/uuid:3ce05448-84b7-4dc7-ad2e-2883b423a337","Development and Verification of a Star Tracker Algorithm Chain","Visser, G.H.","Verhoeven, C.J.M. (mentor)","2017","Many satellites need to know their attitude. A star tracking system is able to provide this information accurately. The objective of this thesis project is to develop a precise, robust and fast algorithm chain for a star tracker that performs better than the currently used algorithms on that star tracker. The performance of this algorithm chain was verified by simulation. A lost-in-space solution can be done in 200 ms, with a precision of 0.6 arc seconds in pitch and yaw and a precision of 4.8 arc seconds in roll. This performance exceeds that of the old algorithm chain.","space image simulator; star tracker; attitude estimation; star identification; centroiding","en","master thesis","","","","","","","","2022-02-15","Aerospace Engineering","Space Systems Engineering","","","",""
"uuid:49d86db1-8909-4464-af1b-fe1655c9c376","http://resolver.tudelft.nl/uuid:49d86db1-8909-4464-af1b-fe1655c9c376","Development of a generic inflatable de-orbit device for CubeSats","Maessen, D.C.","Beukers, A. (mentor); Gill, E.K.A. (mentor); Bergsma, O.K. (mentor); Zandbergen, B.T.C. (mentor); van Breukelen, E.D. (mentor)","2007","New space debris mitigation guidelines require satellites in low Earth orbit to de-orbit within 25 years after end of life. This effectively limits the orbital altitude of conventional CubeSat satellites to 400-700 km. For CubeSats employing the generic inflatable de-orbit device discussed here, this range is extended to 910 km by increasing the frontal surface area of the satellite. The device essentially is of the attached ballute type and consists of a thin membrane covering an inflatable structure, which is chemically rigidized after deployment. Coatings are applied to the structure to provide protection against the hostile low Earth orbit environment and to manipulate the temperature of the inflatable. The inflation gas is stored in solid form inside a so-called Cool Gas Generator. A preliminary design of the pyramid-shaped device is performed for a 1-unit CubeSat of 1 kg mass, with focus on ease of integration. Initial results of the physical development of the structure are shown. A development model of a flexible connector piece is constructed to which five inflatable tubes are attached at right angles in a leak-tight manner. The method used to bond the tubes to the connector piece as well as attachment of the membranes to the inflatable structure is outlined. Lastly, stowage and deployment of the inflatable structure are discussed. The results indicate that the mass and stowed volume of the complete de-orbit system remain within 9.4% and 10.3% of the CubeSats' total mass and volume.","inflatable structure; cubesat; de-orbit; physical development","en","master thesis","TU Delft, Aerospace Engineering, Design and Production of Composite Structures","","","","","","","","Aerospace Engineering","","","","",""
"uuid:83b71de6-c980-4905-b891-c4f04abb9285","http://resolver.tudelft.nl/uuid:83b71de6-c980-4905-b891-c4f04abb9285","Modeling Rotating Cavitation Instabilities in Rocket Engine Turbopumps","Vermes, A.G.","Lettieri, C. (mentor)","2017","With heavy duty propulsion systems under development for upcoming Mars missions, such as the Space Launch System and the Interplanetary Spaceship, the stability of high-performance liquid-propellant rocket engines is of renewed interest. High-power-density rocket turbopumps forward pressurized fuel to the combustor at high rates. Turbopumps operate at extreme design conditions, where propellants may cavitate, and cause instabilities. Of particular interest is Rotating Cavitation, which is characterized by a non-axisymmetric cavity distribution that rotates super-synchronously with the pump impeller. Rotating Cavitation can cause severe structural vibration and fatigue fracture, which have, and may again lead to loss of the mission. Rotating Cavitation is traditionally suppressed through casing treatment. To comply with the high market pressure dictated by the private space sector, it needs to be suppressed through impeller design, before expensive production and testing initiates. Despite significant research, no general impeller design guidelines exist to avoid the onset of Rotating Cavitation. State-of-art predictive methods are either prohibitively time-consuming, or yield limited prognostic capacity. Predicting Rotating Cavitation requires time-accurate 3D numerical assessment, and an explicit understanding of the physics that drive its mechanism. It has recently been hypothesized, that Rotating Cavitation is caused by strong coupling of cavity dynamics between blade passages, which is governed by blockage. This hypothesis facilitates the blockage-based assessment of Rotating Cavitation, which is presented in this thesis. The goal of this project is to devise a new numerical capability to predict Rotating Cavitation during the design phase of turbopumps. This is achieved by reducing the computational cost of calculations. Mesh dimensions and the complexity of governing equations can be reduced by accounting for viscous- and cavity-blockage with models derived from first principles. Reduced-order blockage models are incorporated into inviscid, one-phase numerical simulations. The method is validated through comparison with high-fidelity simulations and experimental data from literature. The total-to-total pressure characteristics of a 2D cascade is captured within 0.26% error, and the flow displacement due to cavity formation on a hydrofoil within 5% error. Rotating Cavitation is captured in a 2D cascade, at an order of magnitude less computational cost than what high fidelity methods require. The thesis proves the hypothesis, that Rotating Cavitation is a purely blockage-driven phenomenon.","turbopump; flow instability; rotating cavitation; blockage model; body force method","en","master thesis","","","","","","","","2018-04-12","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:9e0a6ef6-53ac-422d-9771-16cd8225072c","http://resolver.tudelft.nl/uuid:9e0a6ef6-53ac-422d-9771-16cd8225072c","Wing aerostructural optimization using the Individual Discipline Feasible architecture","Hoogervorst, J.E.K.","Elham, A. (mentor)","2016","At present, on the aviation market a need exists for lighter and more efficient aircraft than the ones dominating the airspace today. Beside the reduction in operating costs and air pollutants of these new generation aircraft, this reduction in fuel use can result in several advantages with respect to the performance of the aircraft like increased range, increased payload capacity, decreased of take-off field length and decreased take-off noise. The present thesis is an effort to contribute to this reduction of fuel use by performing a gradient-based aerostructural wing optimization of a modern high-speed transport aircraft, the Airbus A320, for minimal necessary fuel weight while maintaining its range specification. The novelty of this work is the use of the Individual Discipline Feasible (IDF) architecture instead of the traditional Multidisciplinary Feasible architecture. Using the IDF approach the disciplines within the aerostructural optimization are completely decoupled. The consistency of the system as a whole is maintained by the use of equality constraints to equate the output of one discipline to the input of another. No coupled sensitivity information is required because of this decoupled system. This makes the system not only simpler, but also provides more freedom in software choice for the disciplinary analyses. Furthermore, the time to perform optimization is reduced as the work of making the system consistent is removed from the computationally expensive individual disciplines and put it in the hands of the cheap optimization algorithm. The CFD solver SU2 is used within the aerodynamic discipline to deform the grid, calculate the flow properties and gain sensitivities of lift and drag with respect to surface perturbations of the wing. The Euler model is used and the viscous drag component is calculated using a separate estimation. For the structural discipline the FEMWET software is used, providing the structural data including the static aeroelastic deformation of the wing. The optimization design variables are selected to be the angle of attack, the exterior shape of the wing, being the airfoil and planform shapes, and the thicknesses of the equivalent panels representing the internal wing box. The problem is constraint by compression, tension, shear, buckling and fatigue failure modes. Moreover it is constraint by a minimum aileron effectiveness and a maximum wing loading. The aerodynamic analysis is performed under cruise conditions while the wing structure is analyzed under the critical load cases of the reference aircraft. The optimization algorithm chosen is the Sparse Nonlinear Optimizer, based on the Sequential Quadratic Programming optimization algorithm. The optimization resulted in a reduction of the aircraft fuel weight of 11%. This has been achieved by reducing induced drag through an increase in span and an improved lift distribution, by reducing wave drag by improved airfoil shapes and by reducing wing structural weight by a reduction in wing sweep.","aerostructural; MDO; wing; optimization; SU2; FEMWET","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","Flight Performance and Propulsion","",""
"uuid:b9fa73fa-5cf7-451c-86ae-cc4df0eff3fb","http://resolver.tudelft.nl/uuid:b9fa73fa-5cf7-451c-86ae-cc4df0eff3fb","A Nanosatellite Mission for Ionospheric Disturbance Monitoring: Mission Design and Payload Description","Biersteker, S.","Verhoeven, C.J.M. (mentor)","2016","Military operations have over the last years become more dependent on communication, navigation and intelligence through satellites. In order to expand space activities in the future and to make more informed decisions on space projects, it was decided that the Royal Netherlands Air Force will perform a pathfinder mission. This thesis investigates the options and return for such a pathfinder mission. From a variety of possible mission applications, ionospheric disturbance monitoring was selected. The mission addresses a current issue; signal fades of navigation and communication links in the hours after sunset. Plasma bubbles are causing signal distortion, which is called ionospheric scintillation. Scintillation is noticeable on GNSS signals, but is much more severe at lower frequencies such as UHF. On these lower frequencies, used by the military for satellite communication, scintillation can lead to signal disturbances or fades of up to 50 dB. Widely available GNSS signals can be used for detecting scintillation, but are only a good scintillation indicator for the 1.2 or 1.5 GHz frequency bands. Whether GNSS and UHF signals are distorted, and how severely this disturbance is, depends on the scale lengths inside the ionospheric irregularity. A nanosatellite provides an excellent platform for doing in situ ionospheric measurements and to determine these scale lengths. A combination of a sweeping Langmuir probe, a fixed bias Langmuir probe and an impedance probe was found to be able to provide the required plasma parameters. When the RNLAF chooses to select this mission concept, the variability of the ionosphere and the influence this has on the data return, should be taken into account. The probability of occurrence in a solar minimum year, such as 2018, is expected to be low. An orbit analysis model has shown that a 400 day mission can provide up to 0.68 ionospheric disturbance measurements per day on average. The gathered data will contribute to the characterization of ionospheric scintillation and provide the RNLAF with a means of correlating GNSS and UHF disturbances.","nanosatellite; ionosphere; scintillation; systems engineering","en","master thesis","","","","","","","","","Aerospace Engineering","Space Systems Engineering","","","",""
"uuid:b7077ebe-6404-425b-beff-14d6cf5bb0a0","http://resolver.tudelft.nl/uuid:b7077ebe-6404-425b-beff-14d6cf5bb0a0","Dynamic Crew Pairing Recovery","Hoeben, N.J.M.","Lopes dos Santos, B.F. (mentor)","2017","Introduction An aircraft breakdown, crew coming late, or bad weather conditions are examples of disruptions that airlines have to cope with on a daily basis. Even small disruptions might cause infeasibility of airline schedules. Currently, operation controllers of most airlines solve disruptions manually at the day of operation. They attempt to make the schedules feasible again and strive to return to the original schedule as soon as possible. In addition, it is of great importance to minimize the costs. However, dealing with all the rules, regulations, preferences and costs makes that the recovery process is a complex problem. Therefore, decision support tools need to be developed to assist operation controllers during the recovery process. A decision support tool can provide several solutions to the operation controllers considering all kind of parameters. However, it is of great interest that solutions are generated in short computation times since decisions have to be made in a short amount of time. This research project considers the crew recovery problem, since crew recovery is one of the hardest recovery tasks. Many regulations have to be considered and human factors are involved as well. In addition, after fuel costs, crew costs are one of the largest costs of an airline. Therefore, in this research project a decision support tool is developed for the crew recovery problem. This Master Thesis research project is conducted at the University of Technology Delft (TU Delft). More specifically, at the Air Transport and Operations department from the faculty of Aerospace Engineering. Furthermore, the research is conducted in collaboration with Kenya Airways (KQ).","","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Aerospace Transport & Operations","",""
"uuid:fb5fb1a4-0801-4fdf-aede-577a9202aa38","http://resolver.tudelft.nl/uuid:fb5fb1a4-0801-4fdf-aede-577a9202aa38","Magnetic Nozzles: Experimental Characterization of the plume expansion in the magnetic nozzle of a helicon plasma thruster","Wijnen, M.","Zandbergen, B.T.C. (mentor)","2017","This thesis is concerned with characterising the plume expansion in the magnetic nozzle of a helicon thruster. The investigation took place in the context of the new electric propulsion laboratory of the Space Propulsion & Plasmas Group (EP2) of University Carlos III of Madrid (UC3M) and the testcampaign of the helicon plasma thruster HPT05 prototype that is a joint project of SENER and EP2. The magnetic nozzle is a new plasma acceleration concept that can be used on several different electric thrusters. The helicon plasma thruster is a new type of electric thruster that aims to achieve high thrust density by using a helicon plasma source. The focus of this work is threefold: development, testing and application of electrostatic probe diagnostics for the EP2 lab; characterising the plume expansion and comparison to DiMagNo (magnetic nozzle model) simulations. Some figures of merit about the helicon thruster performance are estimated along the way. The diagnostics used in this thesis are simple and RF-compensated Langmuir probes, Faraday probes and emissive probes. Langmuir probe measurements were found useful for inferring the plasma density and providing the electron temperature which were found to be of the order of 〖10〗^16-〖10〗^18 m^(-3) and 3-5 eV respectively. RF-compensated probes could not be verified correctly as in the low plasma densities of n<〖10〗^19 m^(-3) one of main assumptions, ω_rf≪ω_pi was not valid. The emissive probe was operated in the floating potential in the limit of large emission method providing a fast and precise means to measure the plasma density. A Faraday probe was used to measure the ion current density. All probes are mounted on a three degrees of freedom (3-DOF) positioning system to provide spatially resolved measurements of the corresponding plasma parameters. The plume expansion was found to be independent of the the RF-power in both radial and axial dimension; the shape of the plume is therefore mainly determined by the shape of the magnetic nozzle. Observed radial asymmetries in plasma potential and electron temperature are attributed to the shape of the antenna. The downstream evolution of the electron temperature showed signs of polytropic cooling with γ_e=1.10±0.05 at 500 W operation while at higher power (>650 W) the observed behaviour was isothermal. The plume divergence half angle was found to remain constant downstream (>120 mm) indicating ion detachment from the magnetic fields lines. This was further corroborated by the downstream increase of the ratio of ion to magnetic flux. The presence of the magnetic nozzle significantly improved the plume divergence, decreasing the divergence half-angle with 7°. The axial evolution of measured plasma parameters in the plume were compared to the DiMagNo simulation for the nominal (500 W) case, which showed overall good agreement of ion Mach number, plasma potential, ion current density and plasma density1. Including the polytropic model for electron thermodynamics into DiMagNo was necessary to achieve agreement between simulation and measurement of the ion Mach number. Results were also compared to results from similar thrusters found in literature and good agreement was found particularly with Takahashi [80] and Little [49, 50]. This work helped develop the diagnostic capabilities of the EP2 electric propulsion lab and paved the way for future experiments on magnetic nozzles and validation of the DiMagNo code.","","en","master thesis","","","","","","","","","Aerospace Engineering","Space Systems Engineering","","","",""
"uuid:316904df-d86b-415c-803a-9a94df225b21","http://resolver.tudelft.nl/uuid:316904df-d86b-415c-803a-9a94df225b21","Aeroelastic Modelling of Composite Rotor Blades","Janssen, M.","Voskuijl, M. (mentor); Pavel, M.D. (mentor); Jongbloed, A.A. (mentor); Kassapoglou, C. (mentor)","2015","This thesis was conducted at KVE Composites Group (The Hague, The Netherlands). The aim of this thesis is to create an aeroelastic model that can be used during the design phase of these rotor blade projects. An aeroelastic was created consisting of a Ritz-Hamilton structural model, a lifting line quasi steady aerodynamic model with two inflow models. The aeroelastic model includes effects due to centripetal and gravity forces and conservation of angular momentum. A fourth order Runge-Kutta integration method is used to numerically integrate the aeroelastic model to obtain the response of the system. The aeroelastic model was validated by comparing results calculated using the aeroelastic model with theoretical results and results obtained by measurements. A uniform beam and several rotor blades were modelled for this validation. The calculated steady state deflections and natural frequencies of the uniform beam were compared with values obtained from literature. The calculated steady state deflections and natural frequencies of the rotor blades were compared with values obtained from measurements on the rotor blades. The calculated drag for the rotor blades was compared with values obtained in a series of whirl tower tests. The predicted steady state response and natural frequencies of a uniform beam are very close the values from literature. The error for the steady state response and natural frequencies of a rotor blade is larger than that for the uniform beam. This error reduces if more elements are used. The power required predicted is higher than the power required measured at low angels of incidence and within the bounds of power required measured for high angles of incidence. Using this model KVE is able to predict initial loads, deflections and the consequences of changes in the design of their rotor blade.","rotor; blade; aeroelastic; modelling; aeroelasticity","en","master thesis","","","","","","","","2020-02-15","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:131b6977-bcca-4862-9a63-b80df5070f43","http://resolver.tudelft.nl/uuid:131b6977-bcca-4862-9a63-b80df5070f43","Investigation of Trailing Edge Sub-Components in Wind Turbine Blades","Lachance-Barrett, S.","Teixeira de Freitas, S. (mentor)","2016","","","en","master thesis","","","","","","","","2017-08-26","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:4beac0da-6f4d-492c-96ea-e72a0dbe2493","http://resolver.tudelft.nl/uuid:4beac0da-6f4d-492c-96ea-e72a0dbe2493","Gust tailoring in a wind tunnel for bird and MAV flight experiments","Miñano González, S.","van Oudheusden, B.W. (mentor); Quinn, D.B. (mentor)","2017","","","en","master thesis","","","","","","","","2017-02-23","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion (AWEP)","","","",""
"uuid:59865146-4b7a-4357-9d21-4e8a9469bfda","http://resolver.tudelft.nl/uuid:59865146-4b7a-4357-9d21-4e8a9469bfda","Human demonstrations for fast and safe exploration in reinforcement learning","Schonebaum, G.","Van Kampen, E. (mentor)","2016","","reinforced learning; autonomous control; human demonstrations; online; model-free","en","master thesis","","","","","","","","2021-05-27","Aerospace Engineering","Control and Operations","","","",""
"uuid:a459a8fa-f8cb-4cfa-8b90-b41edbbab67e","http://resolver.tudelft.nl/uuid:a459a8fa-f8cb-4cfa-8b90-b41edbbab67e","Comparison of the Aeroelastic Free Vortex Wake Code AWSM with Conventional BEM Based Codes on 10MW+ Wind Turbines","Hartvelt, M.","De Beuker, R. (mentor); Madsen, H.A. (mentor); Boorsma, K. (mentor)","2016","The current practice in aerodynamic design and load analysis of wind turbines is to use codes based on the Blade Element Momentum theory (BEM). These models are computationally very efficient but are limited in the physical representation of certain flow phenomena, such as yawed flow, dynamic inflow and root/tip flow, for which engineering corrections are applied. In this study the aeroelastic free vortex wake code AWSM is compared to a BEM model for a set of dynamic load cases. The aerodynamics of the global flow are solved fundamentally different: AWSM calculates three-dimensional effects intrinsically by bound vorticity on the blades and shed and trailed vorticity in the wake, whereas the BEM model requires engineering corrections for three-dimensional effects.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","","",""
"uuid:7db354c0-aad4-4ce6-9a8b-5d9775a64156","http://resolver.tudelft.nl/uuid:7db354c0-aad4-4ce6-9a8b-5d9775a64156","Pulsed Fusion Space Propulsion: Computational Ideal Magneto-Hydro Dynamics of a Magnetic Flux Compression Reaction Chamber","Romanelli, G.","Cervone, A. (mentor)","2016","Verifying the working principle of a magnetic flux compression reaction chamber might be crucial for the development of pulsed fusion propulsion: a system that has been projected to possibly revolutionise manned space exploration. For that purpose, an exhaustive computational MHD analysis is a necessary step. This master thesis investigated the possibility of using PLUTO to estimate the ideal-MHD of a multi-coil parabolic reaction chamber. PLUTO is a freely-distributed and modular code for computational astrophysics that, although not originally programmed for engineering applications, has demonstrated great adaptation capabilities: implementing the boundary conditions to effectively emulate a magnetic flux compression reaction chamber has eventually been possible. Besides, the attained results are in accordance with theoretical projections and previous numerical analyses. However, the outcomes pointed out that ideal-MHD could be an over-simplified model: relativistic conditions, that are not properly reproduced by the ideal-MHD equations, have been identified in several locations of the computational domain. In addition, some aspects of the real system physics have yet to be thoroughly investigated as well as mathematically described. Therefore, further investigations are required. According to this research, no other computational analyses of a multi-coil parabolic reaction chamber (i.e. the latest and most promising magnetic flux compression reaction chamber concept) have been found in the literature. Therefore, the results hereby reported contribute to the body of knowledge of plasma physics and nuclear fusion applied to space propulsion.","nuclear fusion; plasma; reaction chamber; magnetic flux compression; computational mhd; mhd; rmhd; numerical analysis; computational analysis; magnetic nozzle","en","master thesis","","","","","","","","","Aerospace Engineering","Space Systems Engineering","","SSE","",""
"uuid:b36760db-c9fe-4ab5-8112-72b2c9b097ce","http://resolver.tudelft.nl/uuid:b36760db-c9fe-4ab5-8112-72b2c9b097ce","Importance of Aerodynamic Load Corrections on the Aeroelastic Tailoring of Composite Aircraft Wings","Ratan Parkhe, K.K.","De Breuker, R. (mentor)","2016","The importance of aeroelastic tailoring is increasing continuously as the aircraft wings become more and more flexible. Incorporating aeroelastic considerations in the early part of the design process has a lot of benefits. But these require significant computational resources if accurate predictions are needed. This is more relevant these days when most of the commercial aircraft operate in the transonic regime. To predict the flow phenomena that occur at such conditions, accurate CFD results are needed. These can be computationally expensive in the early stages of design. To overcome these restrictions, various multi-fidelity approaches are gaining wide acceptance. These methods include a low-fidelity model that does bulk of the work and a high-fidelity model that provides corrections that fill in the deficiencies in the low-fidelity model. The aim is to achieve a high-fidelity result without performing as many high-fidelity computations. These become even more attractive in the context of aeroelastic tailoring as in an optimization routine performing a high-fidelity analysis is infeasible. For this thesis, a defect-correction based multi-fidelity approach has been implemented in an aeroelastic tailoring routine. The Vortex Lattice Method (VLM) was used as the low-fidelity model and SU2 was used as the high-fidelity compressible solver. The designs from the multi-fidelity approach have been compared with the corresponding ones obtained from a purely low-fidelity optimization. To correlate the effects of compressibility with the difference in design, this study was performed at 3 flow speeds; low-subsonic, high-subsonic and transonic. The results for both the subsonic cases are on expected lines, where both the designs closely resemble each other. The designs at transonic speeds show an intersting behavior where the multi-fidelity design is slightly heavier than the low-fidelity design. This was seen to be primarily due to the difference in the aerodynamic torsional moments in the two models due to the presence of a shockwave which was captured by the high-fidelity model. Based on these findings, certain conclusions have been made and recommendations for future work have been provided.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:c796ad94-aa00-4505-bae0-bc4a163ae94a","http://resolver.tudelft.nl/uuid:c796ad94-aa00-4505-bae0-bc4a163ae94a","Source Term Modeling of Vortex Generators","Stam, C.J.","Velte, C.M. (mentor); Timmer, W.A. (mentor)","2016","Vortex generators (VGs) are effectively used to improve the performance of the wind turbine blades by means of flow control. VGs can be represented by local geometrical disturbance on the aerodynamic surfaces. This disturbance generates vortices in the streamwise direction, energizing the boundary layer and hence delaying or suppressing the flow separation. In this way, the entire flow field is reshaped. Use of Computational Fluid Dynamics (CFD) combined with the experiments is desirable to be able to find the most efficient geometrical shape of VG and the installation of it based on the flow characteristics of the problem. However, there is a challenge of using CFD for VG simulation which is the large number of grid points required to obtain an accurate solution. One of the ways to overcome this difficulty is to model the effect of VG. Therefore this thesis will investigate the ways to model a vortex generator and validate the capability of such a model to simulate the optimal VG shape and installation.","Windenergy; vortex generators; computational fluid dynamics; boundary layer control; source term modeling","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","EWEM European Wind Energy Master","",""
"uuid:c97c4389-3d4e-42d4-8d69-14c8fbce9469","http://resolver.tudelft.nl/uuid:c97c4389-3d4e-42d4-8d69-14c8fbce9469","Design and realization of a setup for mechanical tests on a MEMS based micro gravity-gradiometer","De Simone, A.","Visser, P.N.A.M. (mentor)","2008","","mems; gravity gradiometer; accelerometer","en","master thesis","TU Delft, Aerospace Engineering, Astrodynamics and Satellite Systems","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2339ce7d-73a0-4f68-b7ad-db1f23b7ceca","http://resolver.tudelft.nl/uuid:2339ce7d-73a0-4f68-b7ad-db1f23b7ceca","Visually Augmented Simulator-Based Training of the Manual Landing Flare","Ravesteijn, C.","Pool, D.M. (mentor); Borst, C. (mentor); van Paassen, M.M. (mentor); Mulder, M. (mentor)","2016","Landing is one of the most difficult tasks of flying an aircraft and a majority of the incidents and accidents is related to the final approach and landing phase of flight. Comprehensive training programs are required to prepare (novice) pilots for this last phase of flight, and facilitate the development of robust manual flying skills. Various non-aviation studies have shown that using augmented reality in training environments to provide additional insight in the training of specific events or maneuvers, can lead to increased performance during training. However, relatively little is known regarding the effects of visually augmented reality to enhance (novice) pilot training. A quasi-transfer-of-training experiment with 24 novice participants was conducted in the SIMONA Research Simulator to investigate the effect of two augmented reality flare displays on the performance of the manual landing flare. Three groups, of 8 participants each, were asked to perform a final approach and flare maneuver in a Cessna Citation I model. Group 1 trained without visually augmented cues, group 2 trained using an augmented reality display emphasizing naturally present visual cues used throughout the flare maneuver, while group 3 was trained using an augmented reality display providing visual situational-guidance augmentation for the flare maneuver. Training was followed by a two-step evaluation phase where all groups used the non-augmented display. Results of the experiment show that situational-guidance augmentation presented in the context of the landing flare can be beneficial to train novice participants towards a specific standard framework, achieving slightly better performance during approach, on touchdown location, as well as consistency in the throttle closing altitude. No augmentation dependency was found during the two-step evaluation phase for either of the augmented groups, indicating generalizability of the trained skills.","augmented reality; pilot training; transfer-of-training; flare; display design; SIMONA","en","master thesis","","","","","","","","2021-12-22","Aerospace Engineering","Control and Operations","","Control and Simulation","",""
"uuid:257dc92a-d8df-4b2d-8715-6a69b4aa3ddd","http://resolver.tudelft.nl/uuid:257dc92a-d8df-4b2d-8715-6a69b4aa3ddd","Consistent formulation in isogeometric topology optimization for structural applications","Salden, P.H.W.","Turteltaub, S.R. (mentor)","2016","Topology optimization is an automated design approach for structural applications that is gaining popularity in industry, including the aerospace sector. Resulting designs can be made suitable for traditional manufacturing techniques, although it is a technique that is particularly useful for non-conventional approaches such as additive manufacturing. The procedure allows for choosing a design objective, such as minimum compliance or maximum heat conduction. Given one or more constraints, the optimal distribution of material within a domain is computed. A popular topology optimization method is the so-called Solid Isotropic Material with Penalization (SIMP). It is traditionally implemented using piecewise constant density values, specified per element. One technical difficulty with this approach is the formation of “checkerboard-like” patterns where the material is assigned to one element while the adjacent elements contain no material. This issue has been circumvented through the application of filters that explicitly prevent the formation of checkerboards. However, as a result of the filtering process, the designs display structural members with relatively high thicknesses and, at the same time, the structural detail level is relatively low. Several authors in the scientific literature argue that this effect is beneficial from a manufacturing viewpoint. However, recent progress in manufacturing techniques, such as additive manufacturing (also known as 3D-printing), allows to manufacture components with an increased level of detail and complexity. From this point of view, it is relevant to study optimization procedures that preserve the level of detail displayed by unfiltered designs. In this project, SIMP is implemented using Isogeometric Analysis (IGA). In IGA, Non-Uniform Rational B-Splines (NURBS) replace the Lagrange polynomials classically used in Finite Element Analysis (FEA). Through the use of Bézier extraction, implementation changes are confined to the “shape routine”. Rather than working with piecewise constant density values, density is consistently approximated using NURBS. A consistent gradient formulation is derived as well. The effects on checkerboard formation are studied. Instead of filtering, separate meshes are used for density and displacement definition. A displacement mesh is obtained by further refining the density mesh, such that the displacement representation is more accurate. Adequate procedures for Gaussian integration are determined. The treatment is limited to two dimensional minimum compliance problems. It is found that a consistent density representation using NURBS does not prevent checkerboard formation. However, the use of separate meshes for density and displacement diminishes checkerboards. It also generates more detailed designs than those produced by filters. Obtained compliance values are lower as well. Through the use of IGA, arc-like geometries may be studied. At the same time, non-classical checkerboard patterns are observed.","topology optimization; isogeometric analysis; SIMP; Bézier extraction","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:1816a56e-cd0f-4693-8fdc-c91186fe1273","http://resolver.tudelft.nl/uuid:1816a56e-cd0f-4693-8fdc-c91186fe1273","Unsteady Compressible Two-Fluid Flow Model for Interface Capturing: On the Dynamics of a Shock-Bubble Interaction","Kreeft, J.J.","Koren, B. (mentor)","2007","Multi-fluid flows are found in many applications in engineering and physics. Examples of these flows from engineering are water-air flows in ship hydrodynamics, exhaust-air flows behind rockets, gas-petrolea flows in upstream pipes of oilrigs, air-fuel bubble interaction flows in scramjets and many others. To gain better insight in the behavior of multi-fluid flows, especially two-fluid flows, numerical simulations are needed. We assume that the fluids do not mix or chemically react, but remain separated by a sharp interface. With these assumptions a model is developed for unsteady, compressible two-fluid flow, with pressures and velocities that are equal on both sides of the interface. The model describes the behavior of a numerical mixture of the two-fluids (not a physical mixture). This kind of interface modeling is called interface capturing. Numerically, the interface becomes a transition layer between both fluids. The model consists of five equations; mass, momentum and energy equation for the mixture (these are the standard Euler equations), mass equation for one of the two fluids and energy equation for one of the two fluids. This last equation is not conservative, but contains a source term. The source term represents the exchange of energy between the two fluids. The model is discretized by using a finite-volume approximation. The finite-volume method consists of a third-order Runge-Kutta scheme for temporal discretization and a limited second-order spatial discretization. For the flux evaluation Osher’s Riemann solver is constructed, which uses a new set of Riemann invariants that was derived for the two-fluid model. The source term is evaluated using the limited state distribution and the wave pattern in the Osher solver. The two-fluid model is validated on several shock tube problems. The results show that the method is pressure-oscillation-free without special precautions, which is not the case for most other two-fluid flow models. The developed method is applied to two shock-bubble interaction problems. The numerical results really show the competence of the two-fluid model.","shock-bubble interaction; Unsteady compressible two-fluid flow; interface capturing; source term; energy exchange; Osher’s Riemann solver; finite-volume discretization; shock tube problem","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b7269523-affb-43db-9e72-62989fb3329e","http://resolver.tudelft.nl/uuid:b7269523-affb-43db-9e72-62989fb3329e","The assessment of wrinkling and large deformation post-wrinkling of metallic shell structures","Dekker, R.","Kassapoglou, C. (mentor)","2016","Localized buckles can occur in crashes when compressive stresses are dominant. However, due to their local appearance, they might be overlooked by a finite element analysis, meaning that local failure due to buckling will not be predicted. Methods to analytically assess the onset of such buckles are readily available. However, an off-the-shelf solution to predict the behaviour of them after the initial onset is not on hand. Therefore, an analytical method is developed that can predict the behaviour of a buckle after its onset, even in complex multiaxial states of stress that may be expected in crash scenarios. The strain over the buckle is captured as well, meaning that material failure can be predicted using existing material failure models. ","crash; buckling; post-buckling; plastic hinges; wrinkling","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:9138f993-8022-4595-b272-ec711fc77694","http://resolver.tudelft.nl/uuid:9138f993-8022-4595-b272-ec711fc77694","Effect of Geometry on the Downstream Flow Topology of Micro Ramps in Supersonic Turbulent Boundary Layer","Tambe, S.","Schrijer, F.F.J. (mentor); Van Oudheusden, B.W. (mentor)","2017","","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e230606e-611c-49a3-a3d4-51268fd7d12a","http://resolver.tudelft.nl/uuid:e230606e-611c-49a3-a3d4-51268fd7d12a","Inlet Distortion Characterization of the Boundary Layer Ingesting D8 Aircraft","Van Dam, E.M.","Eitelberg, G. (mentor)","2015","This thesis experimentally assesses the inflow towards the propulsors and the pressure distribution at the propulsor fan-face for the boundary layer ingesting D8 aircraft, and examines the dependence of the model, the propulsor and the flight condition on the inlet distortion. Use is made of mini-tuft flow visualization and five hole probe pressure surveys. The results are compared with CFD simulations. The experiments were performed at the most important mission points of the D8: cruise, descent, start of climb, and top of climb. CFD was only performed for cruise and top of climb. From the pressure distributions the distortion coefficient, DC(60), was calculated, the maximum variation in pressure over a specified circumferential segment (60°). At cruise the DC(60) equaled ~0.3, compared to DC(60)~0.1-0.2 for conventional aircraft. The D8 model caused cross-flow to the propulsors, the flow is directed towards the sides of the model. Both fans rotate in the same direction, such that one propulsor has the flow in the direction of rotation, and the other has the flow opposite to the direction of rotation, causing an asymmetry between the left and right propulsor. The flight phase is characterized by ?, the angle of attack, ?, the ratio of tip velocity over tunnel speed, and ?, the yaw angle. It is found that at a high value of ? the pressure differences at the fan-face are reduced by engine suction, lowering the distortion and counter-acting the cross-flow. A low value of ? means a relative lower influence of the propulsor on the flow, such that the propulsor is not able to (fully) counter-act the cross-flow, resulting in a higher difference in DC(60) and power required between the left and right propulsor. Changing ? mainly changes the location of the pressure distributions. The results from experiments agree well with CFD, there is a 1% deviation in DC(60) at top of climb condition, and 6% at cruise. The pressure distributions look similar and the pressure coefficient values scale equally, from -0.8 to 0. Further research should focus on the exact fan response on the distortion. The D8 used conventional engines, optimized for uniform inflow. Developing a BLI optimized engine could further increase the BLI benefit. The D8 model induced cross-flow, resulting in an asymmetry between the left and right engine. Eliminating this cross-flow by a change in model design could also decrease the distortion.","BLI; boundary layer ingestion; distortion; D8; inlet distortion; NASA N+3","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","Aerodynamics","",""
"uuid:e186338b-87eb-4baa-8280-a7940b83db14","http://resolver.tudelft.nl/uuid:e186338b-87eb-4baa-8280-a7940b83db14","Performance analysis and improvement of a small locally produced wind turbine for developing countries","Hosman, N.","van Bussel, G.J.W. (mentor); Sterenborg, J.J.H.M. (mentor); Timmer, W.A. (mentor)","2012","In rural areas of Mali people depend on off-grid gasoline generators for the supply of electricity. Due to the import of expensive gasoline, electricity prices are very high and only few people can afford it. To make electricity cheaper and to stimulate the local economy, local renewable energy sources could be the solution. Due to the use of basic materials and tools for the production, home built wind turbines are one of the most promising alternatives in these regions. The wind turbine designs by Hugh Piggott are famous for this. Although there is a lot of knowledge by many home wind turbine builders about this type of wind turbines, there is a lack of good performance measurements that is required for the further improvement of these machines. This thesis describes the performance identification of a small 1.8 m diameter wind turbine, based on the design of Hugh Piggott. It also presents a new rotor design as an alternative for the current rotor.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","Sustainable Energy Technology","",""
"uuid:e38233ed-91a3-46cc-8376-37fa7c2d8d21","http://resolver.tudelft.nl/uuid:e38233ed-91a3-46cc-8376-37fa7c2d8d21","Conceptual design study of a hydrogen powered ultra large cargo aircraft","Jansen, R.A.J.","La Rocca, G. (mentor)","2017","","Aircraft design; multidisciplinary optimisation; hydrogen","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:6c384e64-9fad-4289-93e8-5a3a863cfed8","http://resolver.tudelft.nl/uuid:6c384e64-9fad-4289-93e8-5a3a863cfed8","Robust Aerodynamic Optimization through Conjugate Gradient Method with Taguchi's Theory","He, D.","Dwight, R.P. (mentor)","2015","The main objective of this thesis project is to establish an optimization framework that can carry out robust aerodynamic design tasks. The work is based on the single-point optimization module of the SU2 code, which contains the partial differential equation solver for flow evaluation and gradient calculation based on the adjoint method. The research work can be divided into two parts: the first one is the establishment of the optimization structure and the corresponding implementation. And the second part is the aerodynamic design examples. During creating the framework of the robust optimization process, the conjugate gradient (CG) algorithm is used to establish the main structure (outer loop). With the conjugate search directions provided by the CG method, line searches are implemented with the application of the strong Wolfe condition (inner loop). In order to carry out robust optimizations within the uncertain operating conditions, the format of the objective function should be defined properly. The Taguchi’s robust design theory is used to create the objective function that takes both the performance expectation and the variance into account simultaneously. As the CG algorithm cannot directly deal with constraints, they should be converted to the penalty terms in the objective function. To check the validity of the established robust optimization process, two examples are tested concerning the wave drag reduction of the NACA0012 airfoil under subsonic condition, with lift and thickness constraints. The first problem is to reduce the drag under the uncertain Mach number and angle of attack which obey certain kind of normal distributions separately. The continuous probabilities of the two uncertainties are firstly discretized into 9 operating conditions and the joint probability is calculated. After that optimizations are carried out under these sampled conditions. The results show that the process can indeed provide robust drag reduction. Compared to the results of the two single-point optimizations under different conditions, the drag value is effectively reduced especially under higher Mach numbers and larger angles of attack. The change of the weight factor distribution for the drag expectation and the variance has noticeable influence on the drag value under the most critical condition. The second problem is to reduce the drag within a certain range of the Mach number while keep a constant lift. The Mach number is the only uncertainty source and it is discretized at 3 sampled points. The results show that the shock wave can be eliminated under all 3 conditions. As a result, both the drag expectation and the variance are significantly reduced. The robust optimizations with different weight factor distribution have similar results except for the one that only focuses on the drag variance reduction. The latter optimization provides a result with nearly no drag variance at the cost of higher drag values throughout the whole tested domain. And the drag increases more quickly than other robust optimization results with the increment of Mach number. Actually, for this problem, a single-point optimization under the highest Mach number could also provide robust drag reduction performance. The test examples preliminarily proved the validity of the established robust optimization process. However, it is recommended that the effectiveness should be further tested with more complicated problems in the future.","robust; conjugate gradient; Taguchi's theory","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:b9969545-069a-4fcb-9b4f-5b8447494cdd","http://resolver.tudelft.nl/uuid:b9969545-069a-4fcb-9b4f-5b8447494cdd","A Knowledge Based System to Support Design for Selective Laser Melting","Van Toor, J.A.","Steenhuizen, D. (mentor); Bosman, M. (mentor); Leary, M. (mentor)","2014","Modern Computer Aided Design/Engineering can assist in the design of highly optimized engineering structures. Such structures allow for a significant reduction on the strain of resources across the product life cycle, where the potential for weight reduction is most beneficial for the aerospace industry. However, their production is currently limited due to the limited design freedom of conventional processes. The design freedom of Selective Laser Melting may provide a solution, as this would allow the production of the optimized structures. Unfortunately, this vastly dimensional process is highly complex due to its highly transient heat transfer. Two main barriers are withholding adoption in the aerospace sector. Firstly, a lack of process control and understanding is limiting the design freedom. Secondly, a lack of process repeatability and standards are prohibiting process certification. A Knowledge Base System was developed for the centralization and standardization of knowledge, on the effect of input parameters on process performance. Novel methods for Design for Manufacturing, and Design for Cost were developed and validated using a Design of Experiments.","Additive Manufacturing; 3D printing; Selective Laser Melting; Heat Transfer; Knowledge Based System; Design for Manufacturing; Design for Cost; Knowledge Based Engineering","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:02f88115-1dbe-468b-b9d6-854657b4ba70","http://resolver.tudelft.nl/uuid:02f88115-1dbe-468b-b9d6-854657b4ba70","Time-Dependent Methods for Stochastic Differential Equations","Oostelbos, J.C.","Gerritsma, M.I. (mentor)","2010","In the last few decades, enormous progress has been made in the field of Computational Fluid Dynamics (CFD). Computers became powerful enough for full-scale simulations and smart algorithms enabled engineers to simulate intricate phenomena like for example turbulence. However, these developments do not stop, and a promising, new area of research is the incorporation of uncertainty quantification in these CFD simulations. Since traditional statistical methods like the Monte Carlo method are useless in these cases due to computational cost, deterministic solutions are sought.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:840bc539-1a52-4ef0-b38c-9f5a50f60947","http://resolver.tudelft.nl/uuid:840bc539-1a52-4ef0-b38c-9f5a50f60947","Design of a Wing with Boundary Layer Suction: Redesigning the Wing of the Eaglet","van de Wal, H.J.B.","Bijl, H. (mentor); Boermans, L.L.M. (mentor)","2010","Over the last century lots of efforts have been put in the reduction of profile drag. By using advanced techniques in airfoil design, the passive ways to reduce profile drag by shaping have come to a standstill due to physical limits. To further reduce the profile drag, an active method has to be used. Boundary layer suction is one of these active methods and its effect is twofold. A laminar boundary layer will be stabilized, preventing transition and yielding larger areas of laminar flow, which generate less drag. On the other hand, turbulent boundary layer separation will be postponed, resulting in a higher maximum lift coefficient. In this thesis it is investigated how much improvement can be achieved by implementing boundary layer suction on the Euro-ENAER EE–10 Eaglet, a research aircraft of the Delft University of Technology. For this aircraft, a new airfoil has been designed in XFOIL which is optimized for boundary layer suction. The new airfoil proved to have good aerodynamic properties with and without suction and showed vast improvements in profile drag. Additionally, the maximum lift coefficient is increased significantly. Also the effects of boundary layer suction on flap and aileron deflection have been investigated. Results showed a significant decrease in drag and increase in maximum lift. With this newly designed airfoil, a new wing was created and its aerodynamic properties were calculated using the lifting line implementation of XFLR. The new wing proved to be more efficient, a drag reduction of 13% was achieved at cruise up to 20% at high flight speeds. However, the drag reduction of the total aircraft was marginally due to the high drag of the rest of the aircraft. At cruise the drag reduction of the total aircraft was about 3.2%.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:fdfd2c25-049c-4c67-a5dc-bad4b8ed1be2","http://resolver.tudelft.nl/uuid:fdfd2c25-049c-4c67-a5dc-bad4b8ed1be2","Multiscale Fracture Simulations for Composite Materials","Van Hoorn, N.","Turteltaub, S.R. (mentor)","2016","For failure in composite materials the fracture mechanisms at the microscopic scale, such as matrix cracking, fiber cracking, fiber-matrix debonding or combinations thereof determine the growth of crack at the macroscopic scale. The goal is to develop a simple failure criterion in terms of a bilinear Traction-Separation Law (TSL) for unidirectional Carbon-Fiber Reinforced Plastic (CFRP) that represents the crack nucleation and evolution at the macroscopic scale. The microscopic fracture mechanisms are incorporated by calibrating this bilinear TSL for arbitrary loading conditions and material properties. The calibration is performed by an extensive parametric study on 2D a Representative Volume Element (RVE) in ABAQUS. For the parametric study five load cases are studied: uni-axial extension (pure mode I), simple shear (pure mode II) and three mixed loading cases. Fracture is simulated inserting cohesive elements along the boundaries of all bulk elements. The effect of five variables was studied: interface cohesive strength, fiber cohesive strength, interface fracture energy, fiber fracture energy and fiber volume fraction. An average of four realizations, i.e. fiber distributions, resulted in an effective TSL that represents the fracture behavior of the RVE. The resulting effective TSL is approximated by a bilinear TSL that has three parameters: initial slope, cohesive strength (peak) and fracture energy (area). Using the results of the parametric study a correlation is performed for these three parameters. First, the mode I and II parameters are correlated using the results of the uni-axial extension and simple shear load case. Secondly, the three bilinear TSL parameters dependence on the mode mixity is correlated using one of the mixed loading cases. As a result of this procedure simple closed-form expressions are established that can determine the macroscopic fracture mechanism, in terms of a bilinear TSL, as a function of the microscopic properties.","fracture; multiscale; failure criterion; representative volume element; ABAQUS; cohesive elements","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Computational Mechanics","","","",""
"uuid:cf1624ce-41b8-4698-9764-206b2763874e","http://resolver.tudelft.nl/uuid:cf1624ce-41b8-4698-9764-206b2763874e","Drag Influence of Tails in a Platoon of Bluff Bodies","Doppenberg, S.P.","Vos, R. (mentor)","2015","Environmental regulations and high fuel prices are of increasing importance for manufacturers of heavy duty vehicles. The main issue is to increase the efficiency of the trucks and to reduce the fuel consumption. When driving on the highway more than 40% of the total energy is lost to aerodynamic drag. This increases the importance of the aerodynamic drag behavior of trucks in developing sustainable transport. This research develops insight in the aerodynamic drag performance of a platoon and the influence of tails on the platoon. To study this problem, a platoon of simplified truck models with rear drag reduction devices is simulated using a CFD program. Different simulations are done where the spacing between trucks is varied, as well as the tail plate angle and the body front rounding. Equipping trucks with tails in a platoon at short spacings leads to an increased drag of trucks directly behind a tail due to the pressure increase by the tail and the inwards deflected streamlines. At short spacings the best way is to only equip the last body with a tail so the streamlines can follow the contours of the platoon and the wake is reduced by the tail. At larger spacings the bodies behave like the isolated bodies but with some minor influence of the wake of the preceding bodies. So at larger spacings the bodies with the lowest drag in isolation are favored. The configuration with tails on all bodies is thus favored. This research shows that equipping trucks with tails in a platoon can definitely be beneficial, but it depends on the spacing between the bodies in a platoon. The best configuration is to drive at the smallest spacing as possible and equip the last body with a tail, so the wake of the platoon is reduced. Since the best configuration of the platoon depends on the spacing, there is another possibility which is to create an automated folding and deploying system to adapt the configuration of the platoon to the spacing between the bodies.","drag; influence; tails; platoon; bluff; bodies","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","Flight Performance and Propulsion","",""
"uuid:1c39f842-6b28-4f72-8fe5-3aec7bc826b1","http://resolver.tudelft.nl/uuid:1c39f842-6b28-4f72-8fe5-3aec7bc826b1","Fuel and Emission Benefits for Continuous Descent Approaches at Schiphol","Inaad, M.","Ellerbroek, J. (mentor)","2016","As the demand for air transportation increases, it becomes more and more challenging for the aviation industry to reduce its CO2 impact. This thesis presents the potential fuel and emission benefits of implementing continuous descent approaches (CDA) at Schiphol International Airport, from cruise altitude to the final approach fix, for a large scope of aircraft types. Using historical data from FMS and ADS-B, fuel-optimal CDAs are simulated using the total-energy model from BADA. By comparing the fuel consumption between the historical flight and the simulated CDA flight, fuel benefits are found. CO2 emissions are then calculated linearly from the fuel benefits. The results show average savings of 92 kg up to 500 kg of fuel per flight. For Schiphol, this results in a total of 39 million kg of fuel savings per year leading to more than 123 thousand tonnes of CO2 savings per year.","BADA; CDA; Continuous Descent Approach; Fuel; Emission; Benefits","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Operations","","","",""
"uuid:3d435cf1-6c2e-476f-91e5-b111c7b55620","http://resolver.tudelft.nl/uuid:3d435cf1-6c2e-476f-91e5-b111c7b55620","Generation of design knowledge from the development of a theoretically idealized wind turbine","Zamora Guevara, Z.H.","van Bussel, G.J.W. (mentor); Zaaijer, M. (mentor); Ashuri, T. (mentor); de Vries, M.J. (mentor)","2010","Wind turbines have significantly evolved in the last three decades, though they still need significant improvements to become more competitive in the energy market. These improvements depend to a great extent on the development of wind turbine technology. In this respect, the design of an idealized wind turbine may provide a potential quantitative insight into further improvement in the design of these systems. Therefore, the objective of this work is to generate design knowledge for wind turbine technology through the development of a theoretically idealized wind turbine. To do so, the concept and the design process of this idealized wind turbine are defined based on the general design theory. Moreover, a design case study is implemented as a demonstration of how the proposed design process is applied. The blade was selected for the case study because it is the most representative component of wind turbines and represents several challenges for the development of the future wind turbine industry. The results of this case study give insight into potential design knowledge generated from the proposed design process. Finally, some recommendations about how the designer can use this knowledge for the improvement of wind turbine design are given.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","Sustainable Energy Technology","",""
"uuid:9344b9b1-a960-4af9-8759-3a989bf133a5","http://resolver.tudelft.nl/uuid:9344b9b1-a960-4af9-8759-3a989bf133a5","Development of the discrete adjoint state method for non-conforming blocks using a finite volume structured multiblock apporach in a CFD software","van Hauwaert, P.D.","Gerritsma, M. (mentor)","2008","","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:49ef7995-12d8-41c3-9fed-5322868aa2bd","http://resolver.tudelft.nl/uuid:49ef7995-12d8-41c3-9fed-5322868aa2bd","Contracting RTA Time Windows for Cost Efficient Aircraft Arrival Scheduling","Te Riet, K.","Mitici, M.A. (mentor)","2017","","","en","master thesis","","","","","","","","2018-04-18","Aerospace Engineering","Control and Operations","","","",""
"uuid:00c02c9f-f940-4aa6-bf40-17757ca6c31a","http://resolver.tudelft.nl/uuid:00c02c9f-f940-4aa6-bf40-17757ca6c31a","Comparison and Application of Unsteady Integral Boundary Layer Methods: Using various numerical schemes","van Es, B.","Ozdemir, H. (mentor); van Oudheusden, B.W. (mentor)","2009","ECN’s project Rotorflow is focused on the development of an aerodynamic module which is able to model the unsteady flow over wind turbine blades. This module is to be coupled to structural dynamics modules for the analysis of wind turbine aeroelasticity . For this aerodynamic module a zonal approach will be used which incorporates an external unsteady potential flow solver and an unsteady integral boundary layer method(IBLM). It was my task to develop an unsteady two-dimensional IBLM from existing methods and then to apply the method using several Finite Differencing Methods (FDM), Finite Volume Methods (FVM) and a particular Finite Element Method(FEM) namely Discontinuous Galerkin (DG). Several systems of IBL equations as well as closure relations have been considered in some detail. All of the considered systems for the IBLM turn out to be hyperbolic and thus warrant the implementation of a Riemann solver. Various test cases were performed and compared with literature, most notably, the impulsively moved and oscillating flat plate and the impulsively moved cylinder. Results show that the unsteady IBLM is able to model the transient behavior correctly, even close to separation, for very high Reynolds number numerical smoothing is required. All finite difference schemes performed well, the same is expected for the finite volume methods. It is advised to apply the closure relations by Matsushita et al for laminar boundary layer flow. Further development is necessary for the DG method as the closure relations give problems in combination with an expansion in basis functions for the flux vector and the source vector.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4ef56c0f-1dbd-4edb-8b89-f672dd3597ec","http://resolver.tudelft.nl/uuid:4ef56c0f-1dbd-4edb-8b89-f672dd3597ec","Design and Analysis of Swirl Recovery Vanes for an Isolated and a Wing Mounted Tractor Propeller","Stokkermans, T.C.A.","Veldhuis, L.L.M. (mentor); Eitelberg, G. (mentor)","2015","In light of the energy crisis of the early 1970's, NASA and industry gained a renewed interest in high-speed propellers for improved propulsive efficiency and explored the idea of swirl recovery vanes (SRV) to generate a net thrust from the residual swirl in the propeller slipstream. After this first effort on the aerial application of SRV, only recently research is resumed. When a wing is introduced in the slipstream of a propeller, for instance for a wing-mounted tractor-propeller, conclusions drawn on SRV in isolated condition may not hold. The objective of this research is to gain an improved understanding of the aerodynamic interaction between the propeller and swirl recovery vanes in an isolated configuration and wing-mounted tractor arrangement in the cruise condition and in a high-thrust condition. This study is realized by performing a series of transient Reynolds-averaged Navier-Stokes CFD simulations of a propeller with and without SRV in an isolated and installed configuration. Throughout this research the 6-bladed propeller of the European APIAN project is used. Available experimental propeller performance, blade pressure and slipstream measurements are used to validate the isolated propeller CFD model. Within the limitations of fully turbulent modelling of the boundary layer by means of automatic wall functions, good agreement is found with the experimental data, including the existence of a conical separation vortex at low advance ratios. Simulated performance and slipstream results are presented of the APIAN propeller with SRV designed for the APIAN-INF test program in the DNW-LLF. PIV measurements in a plane spanned by the radial and rotation axis provide a comparison of the slipstream velocity components and vorticity. This simulation combined with the PIV measurements enables an extensive description of the structure of root and tip vortices induced by the propeller blades and swirl recovery vanes. It is found that the propulsive efficiency increase by the addition of SRV is only 0.57% which is much lower than the design prediction of 1.8%. Therefore this design is not used in the remainder of the research and new SRV designs are proposed. An SRV analysis tool based on lifting-line theory modified for non-uniform inflow is presented. In combination with an optimisation routine, this tool allows for the design of SRV for an isolated propeller. From a simplified analysis of an elliptical vane in a uniform swirl flow, it is concluded that optimisation for maximum SRV thrust is preferred over complete swirl recovery to reach the highest gain in propulsive efficiency. Four designs are presented: Design 1 is optimised for the cruise condition with a constraint on stall for the high-thrust condition. Design 2 is optimised for the high-thrust condition with a constraint on the cruise condition for zero or positive efficiency benefit. These are designs where the SRV have a fixed pitch in flight. Also two variable pitch designs are proposed. The effect of cropping and the number of vanes on the propulsive efficiency is investigated as well for the objective of design 1. Design 1 and 2 are used in CFD simulations behind the isolated propeller to validate the predictions from the SRV analysis tool. In general the simulation results show that SRV lead to an increase in propulsive efficiency by increasing the system thrust over a wide range of advance ratios, with minor effect on the system power. Gains in propulsive efficiency of 0.39% and 0.20% are found in the cruise condition and 2.62% and 3.07% in the high-thrust condition for design 1 and 2 respectively. For high advance ratios the prediction is very accurate, while towards lower advance ratios the tool overpredicts the propulsive efficiency gain. The difference is within the limits that can be explained by the set assumptions. Design 1 proves that it is possible to increase the propulsive efficiency of an operating point close to the point of maximum propeller propulsive efficiency. Design 2 shows that if a larger increase in propulsive efficiency at low advance ratios is desired, the design can be changed at the cost of propulsive efficiency benefit at higher advance ratios, for a fixed SRV pitch design. Downstream of the SRV, somewhat less than half of the swirl is recovered on average. An expansion of the slipstream boundary is present, which is the result of the interaction of propeller blade and vane tip vortices. In the last part the wing of a Fokker 50 is introduced behind the propeller and SRV design 1. The loading on the wing induces an upwash upstream of the wing, resulting in a deviation from the SRV design inflow that is different for each vane by such a degree that flow separation degrades the SRV performance to a large extent. Therefore a change in the SRV design is made by turning each vane over an angle to obtain the time- and radial-average design inflow in the cruise condition. For future research it is recommended to find a different design for each vane. Since the effect of the wing upwash on the SRV inflow field varies with advance ratio and with wing loading and thus varies in flight, a variable pitch SRV design is recommended where the pitch of each vane is adjusted individually. For the cruise condition the increase in propulsive efficiency by the addition of SRV without considering differences in wing drag is found to be 0.93%, which is considerably higher than without wing, mainly due to the increased propeller propulsive efficiency, but partly by increased SRV thrust as well. 2.14% for a medium-thrust condition, which is very similar to the value without wing. For a wing-mounted tractor-propeller conclusions on SRV performance can only be drawn from the complete force balance of thrust and lift of the propeller, SRV, wing and nacelle. Considering the drag of all components, the net increase in propulsive efficiency by the addition of SRV is found to be -0.14% for the cruise and 1.00% for the medium-thrust condition with a net increase in lift of 0.35% and net decrease in lift of 0.55% respectively. Careful optimisation of SRV taking the wing into account as well as the lift as a constraint will most likely result in a performance benefit, since already with this non-optimised design an increase in thrust or lift can be found depending on the advance ratio. The propeller slipstream greatly affects the wing lift and drag distribution by its increased axial velocity and introduced swirl. It is concluded that SRV reduce some of the effects of the propeller on the wing lift and drag distribution by a reduction of the swirl, resulting in a smaller deviation from the wing loading without propeller. A design procedure for SRV should include the wing for instance by an additional lifting line and optimise for combined SRV and wing maximum thrust with a constraint on the net lift. This may lead to SRV designs more focussed on providing the optimal inflow for the wing in order to reduce the wing drag.","Swirl Recovery Vanes; SRV; propeller; APIAN; wing; Fokker 50; CFD; propulsive efficiency; slipstream","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","Flight Performance and Propulsion","",""
"uuid:ff57e3f2-082f-4ac2-86f8-8dbe05d3e213","http://resolver.tudelft.nl/uuid:ff57e3f2-082f-4ac2-86f8-8dbe05d3e213","Mapping and detection of the mesospheric CO2 clouds on Mars using MEx/OMEGA instrument","Leboucher, A.","Stam, D.M. (mentor)","2017","In 1997, the descent of the lander Pathfinder into the Martian atmosphere revealed temperatures in the meso- sphere below CO2 condensation point. As CO2 is the main constituent of the martian atmosphere, the pres- ence of mesospheric CO2 ice clouds has been suggested, and then confirmed by spectro-imaging observa- tions coming from satellite data. These clouds fascinate scientists because none of the current atmospheric models have been able to predict them. They also raise important questions about the martian mesosphere dynamics and properties. Since the early 2000s, a lot of instruments study these clouds in order to detect and map them. These observations are very important in order to be able to model better the atmospheric processes that take place on Mars as the CO2 cycle has a significant impact on its climate. Several studies already developed methods to detect them but now these have to be improved and analysed better to fully characterise the clouds. What I am going to do will be then to analyse the three last years of observation from the OMEGA instrument onboard Mars Express, map the CO2 clouds and study their distribution. The aim of this thesis will be to study the inter-annual variations and the properties of the clouds and try to corre- late them with atmospheric parameters (amount of dust in the atmosphere, temperature, altitude) coming from other observations. The main objective here is to determine how these clouds form and what the source of the condensation nuclei is. With the results of our analysis, the climatology of Mars and its atmosphere dynamics will be refined.","","en","master thesis","","","","","","","","2017-12-31","Aerospace Engineering","Space Engineering","","MSc Space Flight, track Space Exploration","",""
"uuid:fc21b131-b758-44e3-842d-b854a935f5c6","http://resolver.tudelft.nl/uuid:fc21b131-b758-44e3-842d-b854a935f5c6","Hybrid Eulerian-Lagrangian Vortex Particle Method: A fast and accurate numerical method for 2D Vertical-Axis Wind Turbine","Manickathan, L.","Palha, A. (mentor); Simao Ferreira, C.J. (mentor)","2014","The wake geometry of a Vertical Axis Wind Turbine (VAWT) is unlike the standard Horizontal Axis Wind Turbine (HAWT). The blades of the turbine continuously passes through its own wake, creating complex wake-body interactions such as flow separation and dynamic stall, and convectional grid-based numerical method which is capable of describing such near-body phenomena fails at efficiently resolving the wake geometry. However, as these phenomena have a direct impact on the performance of the VAWT, it is paramount that there exists a numerical method that is not only capable of accurately resolving the small-scale near-body phenomena but also excels at efficiently resolving the unsteady large-scale wake geometry. This was the goal of the research and the numerical method that satisfied these requirements was the domain decomposition method known as the Hybrid Eulerian-Lagrangian Vortex Particle Method (HELVPM), based on the doctoral thesis of Daeninck [24] and the additional study performed by Stock [61]. In the present study, we coupled an Eulerian Finite Element Method, which only resolves the near-body domain, with a Lagrangian Vortex Particle Method, which resolves the entire wake. The advantage of such fluid domain segregation was that the Eulerian method could focus on accurately describing the near-body features whereas the Lagrangian method could focus on efficiently evolving the wake using simulation acceleration methods such as Fast Multipole Method (FMM) and parallel computation in Graphical Processing Units (GPU). The present study initially developed, verified and validated the Finite Element method and the Vortex Particle method separately ensuring it performs according to the theory. These methods were then coupled using the algorithm of Daeninck [24] and Lagrangian correction strategy developed by Stock [61]. However, during the study we determined that additional modifications to the coupling strategy is required to ensure conservation of circulation. Furthermore, it was determined that the spatial resolution of numerical method at the overlap region, where coupling takes place, plays a crucial role in the accuracy of the coupling. Even though the hybrid method of the present study sacrificed some efficiency to ensure an accurately coupled scheme, we must not that it is still at its infancy. With the help ofadvanced techniques such as varying particle core size, higher order time marching scheme in the Eulerian method, and boundary element method acceleration techniques such as FMM and/or GPU calculation, the hybrid method has the potential to substantially outperform standard grid based methods. In conclusion, the hybrid method that has been developed here has the potential to accurately describing the near-wake phenomena and efficiently evolving the wake of a VAWT.","Vortex Method; VAWT; Hybrid; Finite Element; Python; Aerodynamics; CFD; Windenergy","en","master thesis","","","","","","","","2014-12-04","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:baa4ce24-84f8-453b-a9d8-95f26b620986","http://resolver.tudelft.nl/uuid:baa4ce24-84f8-453b-a9d8-95f26b620986","Coherent Structures at the Serrated Trailing-Edge of a NACA 0012","Pröbsting, S.","Scarano, F. (mentor); van Oudheusden, B.W. (mentor); Ghaemi, S. (mentor)","2011","In the past, different modifications of trailing-edges have been investigated with the aim to reduce noise emissions. One promising solution, which has been shown to reduce the intensity of trailing-edge noise, is the application of so-called sawtooth serrations with different proportions and sizes. Current research aims at applying new tools of flow field interrogation, first of all tomographic PIV, to the problem of trailing-edge noise and at creating links between the phenomenological description of the flow field in terms of coherent structures and noise spectra in order to improve understanding of the noise generating mechanisms. In the framework of this thesis, sawtooth serrations applied to a NACA 0012 airfoil have been investigated and compared to the straight trailing-edge of the unmodified NACA 0012 baseline model. Acoustic far-field, surface pressure and a series of PIV measurements have been performed for this purpose. In a first step, acoustic far-field measurements on a large selection of serrated models have been performed. On one hand, tonal narrowband noise associated to the shedding of vortices from the blunt parts of the trailing-edge poses a large penalty for the reduction in overall sound pressure level. On the other hand, the acoustic measurements have indicated a small reduction in noise level originating from the serrated trailing-edge for frequencies in the broadband spectrum exceeding the tonal range, which is in agreement with Howe’s theory of trailingedge noise. Overall, a decrease in total sound pressure level could not be observed. In a second step, PIV measurements of the boundary layer close to the trailing-edge have been performed in order to identify a subset of coherent structures, which can be linked to the production of noise and in particular to the production of tonal noise. Large coherent structures appearing close to the trailing-edge or in between the serrations have been visualized, dominate in terms of vorticity level and show the shape of horseshoe vortices. Most of these structures show a large spanwise coherence on the order of the distance between two serrations and reappear at the frequency of the tonal noise. This suggests a link between this category of coherent structures and the tonal noise observed in the acoustic spectra.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d4cf9e7e-5714-4912-9538-fc0420bb7041","http://resolver.tudelft.nl/uuid:d4cf9e7e-5714-4912-9538-fc0420bb7041","Application of Thrust Vectoring to Reduce Vertical Tail Size","Timmerman, L.B.","Voskuijl, M. (mentor)","2017","The vertical tail size of a multi-engine aircraft is typically driven by the directional control requirement during one-engine-inoperative flight. This results in the vertical tail being over-sized for most regularly occurring flight conditions. By adding thrust vectoring technology to an aircraft, the vertical tail can be designed to cope with regularly occurring flight conditions rather than the one-engine-inoperative flight condition. A modern aircraft was redesigned such that it would have thrust vectoring capabilities and an unconventionally small vertical tail. The redesigned vertical tails had areas which were 85\%, 70\%, 60\%, and 50\% of the original vertical tail area, which corresponded to reductions in the vertical tail area of 15\%, 30\%, 40\%, and 50\%, respectively. By reducing the vertical tail area, an aircraft's parasite drag may be reduced, and a reduction in parasite drag would allow for a reduction in the aircraft's fuel consumption. Analyses showed that the redesigned vertical tail and change in aircraft inertia due to the addition of thrust vectoring technology had a negligible impact of the aircraft's roll mode dynamics. It was also shown that the reduction in vertical tail area resulted in a degradation of the aircraft's spiral mode flight qualities. With regards to the Dutch roll motion, a reduction in vertical tail area resulted in a reduction of Dutch roll damping coefficient and Dutch roll frequency. Based on the analysis of the Dutch roll mode, it has been recommended that a compromise between the 85\% and 70\% vertical tail area would likely produce an acceptable compromise between the reduced vertical tail area and Dutch roll flight characteristics; however, the aircraft design would required a yaw damper. It is predicted that trimmed flight with one-engine-inoperative can be achieved by simultaneously using thrust vectoring technology and an unconventionally small vertical tail. Through the use of directional thrust vectoring, an aircraft's rudder deflection angle, aileron deflection angle, and bank angle may reduced during the one-engine-inoperative flight condition. Analysis of the one-engine-inoperative and crosswind flight condition shows that using thrust vectoring for directional control may allow for a reduction in trim drag; however, additional analysis of this flight condition should be completed. A vertical tail mass estimation was completed, and it has been shown that the reduction in vertical tail mass resulting from a reduction in vertical tail area is of the same magnitude when compared to the engine mass increase due to the addition of thrust vectoring technologies. Lastly, it has been shown that an aircraft's mission fuel consumption can be reduced if the aircraft's vertical tail area is reduced and thrust vectoring flight control is implemented into the aircraft design. Reductions in mission fuel consumption greater than 1\% are unlikely; however, there are feasible reductions in mission fuel mass for the proposed thrust vectoring aircraft design.","Thrust vectoring; Lateral directional; Stability and control; Vertical tail; One engine inoperative","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:498466be-1547-4b89-b28c-c006848bfcdc","http://resolver.tudelft.nl/uuid:498466be-1547-4b89-b28c-c006848bfcdc","Evaluation of Intermediate Refueling Stops in Long-Haul Flight Operations","Bos, F.","Hartjes, S. (mentor); Visser, H.G. (mentor)","2014","The aviation sector has suffered a big blow from the series of recent economic depressions. Airlines are struggling to stay in business and are looking for multiple ways to cut on expenses. This has led to the initiation of studies to find strategies which will reduce an airline’s overall fuel consumption. One of these methods is to initiate intermediate refueling stop operations on long-haul flights. This means that instead of flying with a fully fueled aircraft from e.g., Amsterdam to Tokyo, the route is split into two or more segments which are flown with the appropriate amount of fuel and possibly even different aircraft types more suitable for shorter range flight. By developing a novel computer model, this research aims at finding the answers to the following questions: What are the fuel consumption- and emission savings that can be attained by implementing this model on specific routes and with specific aircraft types? What are the route requirements to optimally benefit from operating flights with intermediate refueling stops? Which costs are directly linked to introducing refueling stops, what are the consequences and what can be done to reduce these costs? How does this concept influence the airport groundside operations and what is the impact on the airport infrastructure? The model consists of two independent programs which work in cohesion to find the optimal stopover airport for a specific route operated by a specific aircraft. The first program is the aircraft model, which is capable of calculating the fuel consumption on a specific mission. The calculations are based on the fundamentals of flight and the equations of motion. In total three aircraft types are incorporated and together cover short-, medium- and long range operations. The second program is the route model which is able to identify the costs for a specific segment and determines the optimal route by use of a modified version of the Dijkstra Algorithm and an airport database of ILS Cat. II/III equipped airports. This model computes a buffer zone in which to look for intermediate stop airports and selects the most advantageous option, based on local waiting times, landing- and navigation fees and fuel prices. The results show that on routes suitable for intermediate stop operations, the fuel reduction ranges from 5% - 10%. For the total cost reduction, these values are around 2% - 4% per flight. These figures strongly depend on the mission conditions and stopover position. Besides the fuel price and stopover time, the wind velocity and direction also have a vital role in the feasibility of the concept.","Aviation; Fuel Consumption","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Operations","","Air Transport and Aerospace Operations","",""
"uuid:f85a9c88-7bdb-42cd-a01c-aa85251d365c","http://resolver.tudelft.nl/uuid:f85a9c88-7bdb-42cd-a01c-aa85251d365c","Incremental Nonlinear Dynamic Inversion Flight Control: Stability and Robustness Analysis and Improvements","van 't Veld, R.C.","van Kampen, E. (mentor); Chu, Q.P. (mentor)","2016","Incremental Nonlinear Dynamic Inversion (INDI) is a variation on Nonlinear Dynamic Inversion (NDI) retaining the high-performance advantages of NDI, while increasing controller robustness to model uncertainties and decreasing the dependency on the vehicle model. After a successful flight test with a multirotor Micro Aerial Vehicle (MAV), the question arises whether this technique can be used to successfully design a Flight Control System (FCS) for aircraft in general. This requires additional research on aircraft characteristics that could cause issues related to the stability and performance of the INDI controller. Typical characteristics are additional time delays due to data buses and measurement systems, slower actuator and sensor dynamics, and a lower control frequency. The main contributions of this article are 1) an analytical stability analysis showing that implementing discrete-time INDI with a sampling time smaller than 0.02s results in large stability margins regarding system characteristics and controller gains; 2) a simulation study showing significant performance degradation requiring controller adaptation due to actuator measurement bias, angular rate measurement noise, angular rate measurement delay and actuator measurement delay; 3) the use of a real-time time delay identification algorithm based on latency to successfully synchronize the angular rate and actuator measurement delay together with pseudo control hedging (PCH) to prevent oscillatory behavior; and 4) recommendations regarding control modes, assessment criteria and PH-LAB Cessna Citation specific issues to be used by future contributors to a flight test with INDI on the PH-LAB aircraft.","Incremental Nonlinear Dynamic Inversion; Aircraft Attitude Control; Stability; Robustness","en","master thesis","","","","","","","","2018-10-14","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:b0ab6774-9afa-4ea9-80f2-28d3755fa3fe","http://resolver.tudelft.nl/uuid:b0ab6774-9afa-4ea9-80f2-28d3755fa3fe","Assessment of Fidelity of Candidate Flight Envelopes developed using Computational Fluid Dynamics","Wit, R.B.","Voskuijl, M. (mentor)","2017","At present ship-helicopter qualification testing is an expensive process, both in terms of time consumed (months) and costs (> hundred-thousand euros). The Netherlands Aerospace Centre (NLR) has developed a more effective means for qualification testing - reducing the costs up to 50% and cutting the time required. The key of this process is the so called ’candidate flight envelope’ (CFE), which is a preliminary polar graph that displays the ’candidate’ operational limits of the helicopter for the specific helicopter-ship combination. The candidate operational limits are derived using a combination of the ship’s airwake characteristics and the land-based helicopter margins. The airwake characteristics are described using flow variables cv, χ and φ, which are a derivative of the velocity vector and are determined using the wind tunnel (at present). The CFE is then validated using shortened sea-trials. The NLR has lots of experience with this methodology and is exploring the use of computational fluid dynamics (CFD) to replace the wind tunnel. This research project assesses the fidelity of these simulated CFEs. For that purpose two different numerical solvers have been selected in consultation with the NLR. Deep Purple is a black box flow solver, which has been developed by the NLR, and HyperWorks is a commercial CFD package. Both numerical approaches are based on the RANS equations and use the SST k-ω turbulence model. In Deep Purple two different models of the Royal Netherlands Navy Landing Platform Dock 2 (LPD-2), differing in geometrical complexity have been assessed. Of the most complex geometry two different meshes have been considered. In HyperWorks two different types of (in)flow conditions are applied to the simplified ship model. This means that in total five different simulations have been performed. Optional ’temporal’ and spatial averaging is applied to obtain flow variables cv, χ and φ at various measurement stations located in the flight path of the helicopter. It is shown that the flow characteristics are generally comparable to PIV measurements and show good resemblance to other studies regarding the ship’s airwake. Compared to PIV it is shown that at lower heights above the flight deck, the HyperWorks simulations show better results than the Deep Purple simulations. When validating the flow variables with the wind tunnel, it is concluded that geometrical modeling, spatial averaging and the flow conditions do not show significant differences. Temporal averaging shows better results for Deep Purple but lacks any difference in HyperWorks due to the combination of the averaging scheme and the setup of the governing equations. A thorough uncertainty analysis is required to achieve the goal of safely using a conservative simulated CFE in a real-world environment, without requiring a wind tunnel campaign. For that purpose the ratio of the simulated flow variables to the wind tunnel flow variables, on different locations in the flight path, is defined as the error ratio. Three different definitions of the error ratio distribution, known as ’methods’, are devised. To understand the influence of the error propagation during the envelope generation, the first and third quartile of the error ratio distribution are extrapolated to the CFE using these three methods. Since the generation of the CFE is a non-linear process these quartiles are extrapolated using a minimization and maximization strategy. The envelope’s inner contour is optimized in Matlab by deflecting the flow variables while adhering to an upper and lower bound specified by these quartiles. When validating the simulated CFEs with wind tunnel based CFEs, it is concluded that the most practical and easy to use method is the best method and leads to a conservative envelope in practice. This method may lead to numerical methods being the backbone of CFE generation, increasing cost-effectiveness at a minimum time required.","","en","master thesis","","","","","","","","2027-02-24","Aerospace Engineering","Flight Performance & Propulsion","","","",""
"uuid:053c1ff3-08ee-40b5-b67a-2546f0885b84","http://resolver.tudelft.nl/uuid:053c1ff3-08ee-40b5-b67a-2546f0885b84","Simplified fatigue assessment of offshore wind support structures accounting for variations in a farm","Michalopoulos, V.","Zaaijer, M. (mentor)","2015","The optimal design and preliminary strength assessment of offshore wind support structures gain growing interest given the potential to drive the costs further down. This study develops a framework for Fatigue Limit State (FLS) estimations of monopiles in a simple and quick manner so as to address site variations in an offshore wind farm (OWF). Additionally, it serves the need for optimisation of all structures in the farm in the early design phase. The framework consists of two elements: (a) a stand-alone model that predicts in a simplified way the damage caused by the varying loading and (b) correction factors that increase its reliability. The concept of the model relies on the analytical approximation of the dynamic response, thus by-passing time consuming numerical processes and advanced software. The above step renders it a simplified version of the conventional frequency-domain. Its benchmarking against the time-domain aeroelastic code Bladed yields sufficient accuracy but also certain systematic errors. Effectively, these are tackled by the correction factors that are generated at a reference position where time-domain detailed assessment is necessary. Once calculated, they are transferred to the positions of interest in the farm. A case study examining the variations in a site shows an efficient performance of the proposed scheme: particularly at the parts of the structure close to the seabed with errors lower than 5 % with respect to the outcome of Bladed. Finally, given the fatigue estimations at every location, the foundation piles are re-designed individually in order to fulfil the target of mass reduction. By using the outcome of the case study as input for the tailoring of the geometry, it is shown that a considerable amount of steel, up to 16 %, can be saved.","Windenergy; frequency domain; FLS; tailored design; monopiles","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","MSc S.E.T. (Fac. of Applied Sciences)","",""
"uuid:4ef8ef37-b337-4fbe-a940-858472d2b1a7","http://resolver.tudelft.nl/uuid:4ef8ef37-b337-4fbe-a940-858472d2b1a7","Modeling of a horizontal axis wind turbine with smart actuators","Geurts, B.M.","Simao Ferreira, C.J. (mentor); Sterenborg, J. (mentor); Barlas, A. (mentor); Van Bussel, G.J.W. (mentor)","2009","With the increasing size and complexity of wind turbines, also the risk of failure of a crucial component increases. The expected fatigue life of certain subcomponents is an important design requirement. Fatigue damage is triggered by a periodic loading of the construction. The number of load-cycles (and thus the lifetime) and the amplitude of the periodic loading dominate the fatigue behavior. The lifetime greatly increases if the load amplitude is decreased. One of the possible ways to reduce the periodic behavior of the loading is by applying flaps to the blades of a Horizontal Axis Wind Turbine (HAWT). The flap deflections can be preprogrammed to counteract the periodicity of aerodynamic phenomena like wind shear or yawed operating conditions. In the future, it should even be possible to add a sensing system, calculating in real-time the required flap deflections. With this 'Smart' autonomous system, possibilities open up to even use the control surfaces for non-periodic peak loads occurring due to turbulence or wind gusts. In this master thesis, an aerodynamic model (Vortex Panel Code) is used to investigate the loads on the blades of the HAWT. The simulated wind turbine is an experimental rotor which will be tested in the Open Jet Wind Tunnel Facility (OJF) at the TUDelft. The loads for three different cases are calculated. In a first simulation, the reference condition is analyzed, i.e. the rotor is operating in pure axial inflow. Secondly, the turbine is operating under yaw misalignment. This simulation gives the uncontrolled (and mostly unwanted) periodic behavior of the blade loads. Finally, the effect of a prescribed flap deflection is analyzed. When the output of the flap deflection case is compared to the output of the yaw misalignment case, it is possible to make an estimation of the required flap control in order to reduce or even eliminate the periodic behavior of the loading. The obtained estimations indicate that the smart rotor concept is useful to compensate for periodic structural loadings, but it is not very suitable for applications where the purpose is to level a periodic output of the rotor power.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","AEWE","","","",""
"uuid:f50b743f-f841-4de1-9602-c2e05d5303a6","http://resolver.tudelft.nl/uuid:f50b743f-f841-4de1-9602-c2e05d5303a6","Evaluation of a Lightweight Composite Bottom Plate for Air Cargo Containers","Bode, W.","Bergsma, O.K. (mentor)","2016","Air cargo containers are used to load luggage, freight, and mail on aircraft. They allow a large quantity of cargo to be bundled into a single unit. This study aims to investigate the replacement of the current 14,1kg aluminium floor with a 40% lighter composite in Nordisk containers. The result of these weight savings are yearly cost reductions or an increased turnover for airliners. I have performed analytical and finite element calculations and have conducted small and full scale tests based on the calculation results and requirements. The tests show that the composites do not have sufficient stiffness which caused excessive deflections in the full scale roller tests. Severe wear on the underside of the composite plates made operation impossible after 800 cycles compared to the aluminium 13000 cycles. Analytical calculations show that decreasing the requested weight savings to 30% might be necessary. For a sufficient stiffness, a composite weight of 9,6kg is achievable.","air cargo; aircraft; freight luggage; containers; Nordisk; DSM; ULD; unit load device; lighter; weight savings; composite; panel; roller floor; rollers","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","","52.51346 6.09165"
"uuid:c878e4b8-31c6-4192-84a4-be1576500eab","http://resolver.tudelft.nl/uuid:c878e4b8-31c6-4192-84a4-be1576500eab","Accelerating Wind Energy: A physical approach to monitor tower base fatigue loads using standard signals","Koopman, F.J.","","2013","Keeping track of the experience loads can be of great value for wind energy. If for instance lower loads are found than expected, the lifetime of a wind turbine could be extended beyond its design life. This will lead to a reduction in the cost of energy. Another advantage of so-called load monitoring is that design loads can be evaluated. This could lead to the conclusion that site conditions are different than expected, which means that either the turbine’s operation needs to be altered or the design can be changed for future turbines. Furthermore load monitoring gives insight into turbine behaviour.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:262f37e7-c487-454c-8e0b-69b8c3c61a58","http://resolver.tudelft.nl/uuid:262f37e7-c487-454c-8e0b-69b8c3c61a58","Phase resolved PIV analysis of an undulating fin: Experimental investigation of the Galatea propulsion mechanism","Vercruyssen, T.G.A.","Scarano, F. (mentor); Poelma, C. (mentor); van Oudheusden, B.W. (mentor)","2010","In the world of underwater measurements and inspections there is a large demand for autonomous underwater vehicles(AUV) to decrease the cost and dangers involved in such operations. Small and low cost AUV can operate in many fields including hydrography, marine geology, coastal engineering and marine biology (habitat mapping). A concrete example is the underwater inspection of ships for illigal goods. At the moment this dangerous task is assigned to divers, but the job can also be done by a stand alone or a swarm of AUV’s. Of course it is a specific example, AUV’s can be used in a very wide spectrum of applications.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6aa1d6a0-0601-4595-97b3-047117fc6a97","http://resolver.tudelft.nl/uuid:6aa1d6a0-0601-4595-97b3-047117fc6a97","Multibody Dynamics Modeling of Flexible Aircraft Flight Dynamics","Kalthof, R.L.C.","Voskuijl, M. (mentor)","2014","Because of the focus on weight minimization, aircraft are becoming more and more flexible. Therefore, the frequency separation between flight mechanics motion and structural vibration decreases. This calls for a flight mechanics model that includes aeroelasticity. The development of such a model was the subject of the current research. This model can be used for gust and maneuver load prediction in the preliminary design phase. With accurate load prediction, structural integrity can be ensured and unstable flight conditions can be avoided. Moreover, the model may be used to design active load alleviation systems to increase passenger comfort, reduce fatigue, and decrease loads on the wing structure. A modal structural model and a quasi-steady aerodynamics model are integrated in a partitioned manner to form an aeroelastic wing model. This aeroelastic wing model is implemented in a multibody dynamics environment, in order to model flight dynamics and the effect of aeroelasticity thereon. An A320-like aircraft was analyzed in the current research. The effect of aeroelasticity on flight mechanics was investigated. Inclusion of flexibility substantially affected the trim control variables, but had an almost negligible effect on the flight mechanics modes and stability derivatives. When flexibility increases, these parameters are affected. Aeroelasticity has a non-negligible effect on the (peak) wing loads after maneuvers or disturbances. Especially for maneuvers or disturbances that increase lift, and therefore wing deformation, the peak loads are affected. Moreover, wing loads are particularly affected by disturbances that have a direct effect on the wing, such as aileron deflection. The objective of the current research was to improve on an existing aeroelastic flight mechanics model, based on the lumped-parameter approach. The modal model created in the current research proved to have a computational effort that is several times lower than the lumped-parameter model. In addition, the accuracy of the modal model can be increased beyond that of the lumped-parameter model at only a small additional computational cost. Because of the reduced computational cost, and the potentially increased accuracy, the modal model performs better than the lumped-parameter model. Due to the qualitative nature of these conclusions, it is probable that they can be extended to other conventional, low aspect-ratio aircraft in the subsonic flight regime. Definitive, quantitative conclusions could not be formulated, because of the absence of complete validation data.","multibody dynamics; aeroelasticity; SimMechanics; flight dynamics","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","Flight Performance and Propulsion","",""
"uuid:558ccd7e-b7b0-4e39-81b8-ee4d9b20d6c5","http://resolver.tudelft.nl/uuid:558ccd7e-b7b0-4e39-81b8-ee4d9b20d6c5","Design and experimental analysis of hat-stiffened panels for thermoplastic wind turbine blades","Blanken, A.","van Bussel, G.J.W. (mentor); Zaaijer, M.B. (mentor); Geuskens, F.J.J.M.M. (mentor); Hulskamp, A.W. (mentor)","2010","Developments in large wind turbine blades point towards a redesign of conventional blade structures into a rib-spar-skin design. Additionally research on thermoplastic glass fibre composites shows promising results, concerning material properties as well as manufacturing and assembly processes, for the application of thermoplastic composites in a rib-spar-skin design of a turbine blade. Thermoplastics are not compatible with traditional core materials of sandwich constructions. A monolithic design on the other hand mixes very well with capabilities of thermoplastic technology, such as rubber forming and welding, and has a potential in cost and weight reduction. This thesis is focused on the design of a hat-stiffened panel as an alternative for a conventional sandwich structure, which is used as a skin in modern wind turbine blades. Although thermoset glass fibre composites are used in this thesis the research is aimed at development of thermoplastic wind turbine blades. A sandwich panel was isolated from a turbine blade design in order to be used as a reference for the design of a hat-stiffened panel. The sandwich panel has been analyzed on failure modes due to longitudinal compression and a reference compression load was established. Several methods were used to develop an optimization methodology for the design of a mass-efficient hat-stiffened panel. In order to validate the theory, a scaled version of the designed hat-stiffened panel was constructed in order to be used in experiments. Furthermore a test rig was designed to provide simply supported boundary conditions during the experiments. Several elastic buckling experiments have been carried out as well as a post-buckling failure experiment.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","Sustainable Energy Technology","",""
"uuid:3c8d42b1-fdf1-47f2-91af-cc71882c75ff","http://resolver.tudelft.nl/uuid:3c8d42b1-fdf1-47f2-91af-cc71882c75ff","Evaluation of close range photogrammetric support for Pavescan","Verlaar, S.H.S.","Lindenbergh, R.C. (mentor); Gorte, B.G.H. (mentor)","2011","Pavescan is a low cost mobile system for road modelling survey. Because of the absence of navigation sensors it has several practical drawbacks compared to most of the other mobile mapping systems, but those sensors are very expensive and do not fulfil most of the accuracy requirements. Pavescan will be more attractive if some of the practical drawbacks are reduced. Pavescan measures road profiles across the road by laser scanning at a series of positions. The separate scans are linked via control points, which have to be measured in an additional survey. The accuracy in height of the scans is most important (e.g. for volume calculations) and has to be in the range of millimetres. It is evaluated if integrating close range photogrammetry can achieve millimeter accuracy of the scan and reduce the number of control points. A test survey was conducted with a downward looking camera, which was mounted close to the scanner at a height of around 3.6 metres above the road's surface. The position and orientation of the camera at each exposure is retrieved by bundle adjustment. The accuracy of the bundle adjustment depended strongly on the configuration of the control points. Due to the narrow shape of a strip of images, this configuration will always be weak. For a sequence of 28 images ( 43 metres), around five control points are needed to achieve sub-centimetre accuracy of the object points. If more than 36 images or fewer than four control points were used, the bundle adjustment diverged (i.e. no solution could be obtained). A reduction of control points is therefore not possible. The practical feasibility for integrating close range photogrammetry into Pavescan is low, since too many control points are needed that should spatially be well distributed and measured with tachymetry (or with similar accuracy). Therefore it is not recommended to integrate photogrammetry in Pavescan.","photogrammetry; laser scanning; Pavescan; control points","en","master thesis","","","","","","","","2010-12-18","Aerospace Engineering","Department of Optical and Laser Remote Sensing","","","",""
"uuid:780071cb-c856-4e8a-8783-915c2df1d8ea","http://resolver.tudelft.nl/uuid:780071cb-c856-4e8a-8783-915c2df1d8ea","Optimal Translunar Lagrange Point Orbits for OLFAR","Vermeiden, H.","Noomen, R. (mentor)","2014","Investigation of the feasibility of using translunar Lagrange point orbits for low-frequency radio wave astronomy, in particular for Orbiting Low-Frequency Antennas fro Radio astronomy (OLFAR). Furthermore suggesting swarm and orbit configurations that lead to the best possible results.","OLFAR; Lagrange; radio astronomy; Near-Vertical Orbit","en","master thesis","","","","","","","","","Aerospace Engineering","Astrodynamics & Space Missions (AS)","","","",""
"uuid:13fd72f6-946b-4fc1-bcfd-ee1d737abe85","http://resolver.tudelft.nl/uuid:13fd72f6-946b-4fc1-bcfd-ee1d737abe85","Robust fleet planning under stochastic demand","Sa, C.A.A.","Santos, B.F. (mentor); Clarke, J.P. (mentor)","2016","The research objective of this thesis is to develop an innovative airline fleet planning concept that is capable to consider the long-term stochastic nature of air travel demand while generating meaningful results in reasonable computation times. The proposed methodology aims to identify robust fleets, in terms of profit generating capability across a long-term planning horizon under stochastic demand, through the adoption of a portfolio of fleets (each of different size or composition) and a three-step modeling framework. The three models involve the simulation and sampling of stochastic demand using the mean reverting Ornstein-Uhlenbeck process, iteration over an optimization model that optimally allocates each fleet from the portfolio given the demand sample values, and a scenario generation model that generates scenarios across the planning horizon. A case study is presented and serves as proof of concept.","airline fleet planning; stochastic demand; optimization","en","master thesis","","","","","","","","","Aerospace Engineering","Air Transport and Operations","","","",""
"uuid:61e4393a-4635-4e5f-b233-228152e07a89","http://resolver.tudelft.nl/uuid:61e4393a-4635-4e5f-b233-228152e07a89","Impact of Electric Taxi Systems on Airport Apron Operations and Gate Congestion at AAS","Soepnel, S.M.L.","Roling, P.C. (mentor); Haanstra, J. (mentor); De Wilde, W.J. (mentor); Busink, J. (mentor)","2015","Growth in air traffic demand and increasing attention for environmental impact of the air travel industry and airports has spurred the innovation of the Electric Taxi System (ETS). The ETS incorporates an electric motor in the main or nose landing gear of an aircraft, powered by the auxiliary power unit (APU) of the aircraft. The system allows the aircraft to maneuver and taxi without the use of its main engines or a tow truck. Thereby, the ETS reduces fuel usage and the environmental impact during the taxi phase of flights. Additionally, the system aims to increase the gate pushback efficiency. The ETS eliminates the need for a tow truck during the pushback process as it allows for autonomous pushbacks. The studies performed on existing ETSs (the EGTS and theWheelTug systems) indicate that time can be saved with autonomous pushbacks using the ETS. KLM Royal Dutch Airlines and Amsterdam Airport Schiphol (AAS) have instigated research to investigate the impact and potential benefits of the implementation of the ETS. This Msc. thesis research work continues the exploration of the ETS’s impact at AAS by posing the following research question: What opportunities does the ETS offer for gate capacity and buffer utilization optimization, and what is the value of the impact of the ETS on apron operations at Amsterdam Airport Schiphol? Thus, the research attempts to draw light on the value of the ETS for operations in the apron environment. With increasing air traffic demand, the gate capacity at Schiphol Airport is nearing its maximum during the airport’s peak hours. Therefore, the potential gate capacity enhancement procedures enabled by the ETS are explored in detail in this research. Additionally, the value of the ETS for the overall apron environment is investigated. The reduction in the need for tow trucks due to the ETS implementation also provides benefits for the apron environment. The ETS presents the possibility for of two gate usage optimization concepts to be implemented more widely,namely; the dispatch towing concept and the pit stop concept. The gate planningmodels designed in this research explore the potential of the implementation of the pit stop and dispatch towing concepts at AAS. Initially, a gate planning model is designed to graphically present the narrow body gate and buffer plan in gantt chart format. In doing so the gate and buffer planning schedule for the busiest day at AAS in 2014 is visualized. The pit stop and dispatch towing concepts are then applied to the schedule where possible. From the visualization of the gate plans with and without the ETS enabled concepts, it can be concluded that the pit stop concept increases gate capacity at AAS by approximately six additionally aircraft on the busiest day at the airport in 2014. Furthermore, the dipatch towing concept increases gate planning efficiency and reduces ground arrival delays for six arriving aircraft on the busiest day at the airport in 2014. The gate planning model is subsequently expanded in order to explore the effect of increased traffic and delays on the gate planning at AAS, and the usage of pit stops and dispatch towing to help increase gate capacity and solve delay conflicts, respectively. From the extended model it becomes apparent that should the number of peak hour flights at AAS increase by 10%, and average of 25% of the additional flights can be scheduled at a gate using the pit stop concept. Should the number of peak hour flights double, an average of 8.8% of the additional peak hour flights (corresponding to 12 flights) can be scheduled using the pit stop concept. Furthermore, the model shows that, between 10% and 12% of the ground delays caused by delayed peak hour flights at the gates can be solved through the implementation of dispatch towing. This results in an average of 17.2minutes saved for nearly 50% of the arriving delayed flights. The gate planning models have indicated the potential of the pit stop and dispatch towing concepts enabled by the ETS for gate planning efficiency and capacity at AAS. However, the implementation of the ETS influences many key performance indicators (KPIs) of the apron area. In order to explore the value of the ETS on the apron area, a value model is developed. The value model is based on the value operations methodology (VOM). The value model qualitative assessment indicates that the ETS can enhance the safety, capacity, and efficiency of the airport apron environment, while reducing the costs and environmental impact of the apron area operations. The results of the models and the research performed can be further analyzed and developed by KLM and AAS in order to assist in the development of electric taxi systems and, eventually, enhance their competitive position within the aviation industry.","Electric Taxi Systems; Gate Capacity; Value Model","en","master thesis","","","","","","","","","Aerospace Engineering","Air Transport & Operations (ATO)","","","","52.30907, 4.763385"
"uuid:a3f7808a-554e-4522-972d-a076012426ee","http://resolver.tudelft.nl/uuid:a3f7808a-554e-4522-972d-a076012426ee","Gas path analysis for the MTT micro turbine","Bauwens, P.L.","Visser, W.P.J. (mentor); Dountchev, I.D. (mentor)","2015","Gas turbine diagnostics is as old as the gas turbine itself. Over the years, performance based diagnostics allowed for a shift from time-based maintenance to more economical condition based maintenance playing a fundamental role in enhancing the availability and reliability of gas turbines. By monitoring the condition of the engine over time, maintenance actions can be taken based on information collected from the field. MTT (Micro Turbine Technology) is currently developing a low cost 3kWe micro-turbine CHP (Combined Heat and Power)-system by using off-the-shelf technologies. Once the system will be launched on the market an organized, cost-effective maintenance procedure will be required. The objective of this M. Sc. thesis project was to develop and demonstrate a Gas Path Analysis diagnostic concept for the micro-turbine. Gas Path Analysis (GPA) is a method to assess the condition of the gas turbine by using performance measurements from the gas path. The feasibility of the diagnostic concept was demonstrated by some case studies using data from the first generation field test units. After reviewing a number of gas turbine diagnostic techniques, a non-linear model based gas path analysis approach was chosen. For the development of the diagnostic concept, a non-linear model of a healthy reference engine was used to simulate the off-design behaviour of the engine and derive healthy performance parameter baselines. These baselines are used to compare the performance of field engines against. A component based modelling environment called GSP or the Gas turbine Simulation Program was used to simulate the effect of ambient conditions and deterioration on performance. The diagnostic concept relies on the principle that deterioration causes corrected measurement parameters to shift from the healthy reference baselines. Measurement performance parameters are first corrected to standard ISA conditions before being compared against the healthy baselines. By modelling specific types of deterioration in GSP, signature parameter shifts could be recorded for each of the deterioration modes. These signature parameter shifts are used to compare shifts in performance parameters against and determine the closest pattern-match which can be used to identify the most probable cause of deterioration. The proposed concept is capable of performing engine level diagnostics and partially component level diagnostics. Multiple fault diagnostics and quantifying the level of deterioration are more difficult due to the limited number of sensors and the relatively large impact of second-order effects such as heat-loss, auxiliary power take-off, mechanical losses, etc. The performance parameter baselines together with the derived rulesets can easily be implemented in a maintenance tool making the concept flexible and easy to use.","micro gas turbine; gas turbine simulation; performance modelling; trending; diagnostics","en","master thesis","","","","","","","","","Aerospace Engineering","Flight performance and propulsion","","Masters","",""
"uuid:a9ef5fcc-9f00-4b99-9625-7e3acbc92996","http://resolver.tudelft.nl/uuid:a9ef5fcc-9f00-4b99-9625-7e3acbc92996","Onset Theory (Strain Invariant Failure Theory): Consistent Approach and Automation","Baar, S.","Kassapoglou, C. (mentor); Turteltaub, S.R. (mentor)","2017","Many composite failure criteria suffer from serious flaws related to prediction accuracy and the number of tests required to apply them, as found for example during the World Wide Failure Exercises. In 2001, Jon Gosse of Boeing Phantom Works developed a new criterion for matrix failure. Initially known as Strain Invariant Failure Theory (SIFT), it was soon extended through collaboration with John Hart-Smith to also include fiber failure. During this process, it was also renamed to Onset Theory. Onset Theory predicts failure using micromechanically obtained strain invariants in the constituents of a composite. As a physics-based criterion, it is claimed to be applicable to all types of loading, boundary conditions, geometries, and layups. However, it has yet to see widespread application. In this thesis, a consistent approach to Onset Theory has been developed. This addresses and resolves the contradictions found in literature regarding the exact details of the application of Onset Theory. In addition to that, failure envelopes are generated for comparison with laminate test data. Previously, finite element models were required for each specimen and state of strain. In this thesis, the entire process has been automated for ease and speed of applicability. Using the consistent, automated approach, Onset Theory is shown to quite accurately predict failure in composite laminates under biaxial strains. This includes non-catastrophic matrix cracking preceding ultimate failure, without the necessity of performing a progressive failure analysis. Onset Theory also correctly captures trends in the difference between lamina and laminate failure. Most importantly, it only requires a single set of critical strain invariants (three in total), regardless of loading condition or stacking sequence. This means that extensive and expensive testing can be reduced significantly.","Composite failure; Onset Theory; Strain Invariant Failure Theory (SIFT); Consistent approach; Failure envelope generation","en","master thesis","","","","","","","","2022-02-27","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:5a3585c4-7083-432d-88de-8c8dc9a3d948","http://resolver.tudelft.nl/uuid:5a3585c4-7083-432d-88de-8c8dc9a3d948","Self-starting of a small urban Darrieus rotor: Strategies to boost performance in low-Reynolds-number flows","Bos, R.","van Bussel, G.J.W. (mentor); Timmer, W.A. (mentor); Geurts, B.M. (mentor)","2012","Like many vertical-axis wind turbines (vawts) of the Darrieus type, Turby fails to achieve a fully passive start-up. Experiments indicate that there is a band of negative torque—often referred to as dead band in literature—somewhere in the tip speed range 0.5 B l B 1.6. The reason behind this is that, unfortunately, the power coefficient obtained at the rated wind speed is all but constant. The combination of low wind speeds and the small scale of the device leads to very low Reynolds numbers; well in the order of < 105. The lift production and stall behavior of the airfoils aggravates in these conditions, with low starting torque as a result. The design case revolved around Turby – a small 1.6 kW, 2.20 m diameter vawt with a projected cut-in wind speed of 3 m/s. The purpose of this master thesis is to investigate the cause of the poor start-up performance and to find possible solutions for the problem. This eventually led to a design proposal.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","Sustainable Energy Technology","",""
"uuid:261087ef-3603-4fb1-bf4a-8db861d15753","http://resolver.tudelft.nl/uuid:261087ef-3603-4fb1-bf4a-8db861d15753","Development of a design tool for offshore wind farm layout optimization: Consideration of wake effects and electrical infrastructure costs and losses","Borbón Guillén, F.","Zaaijer, M.B. (mentor); van Bussel, G.J.W. (mentor)","2009","A design tool has been developed with the aim of helping in the wind farm design process. The tool is able to handle rectangular layouts with any number of turbines. Wind farm power, as well as wind and site conditions can be specified by the user. The main tool models are described and the developing steps have been detailed. Results of tool functionality are presented and compared with other tools or real case studies. The two modes of operation are explained: the separation distance sweep mode and the optimization function mode. Besides, the advantage and limitations of the optimization mode are indicated. The main lessons learnt during the developing of this tool are described for each developing stage. The most relevant is that the optimum layout dimensions should be found using the separation distance sweep mode rather than the optimization function. As a main conclusion, the implemented design tool can be helpful for the design process of offshore wind farms. The tool allows the user to define turbine, wind and site conditions and wind farm layout properties. Based on these properties, the tool delivers the optimum layout dimensions considering the effects of wake losses and electrical cable losses and costs. Additional conclusions and recommendations are summarized together with some future work possibilities.","Windenergy; wind farm optimization; levelized production cost optimization; wake models; design tool","en","master thesis","","","","","","","","","Aerospace Engineering","","","Sustainable Energy Technology","",""
"uuid:acd7e4f7-849b-400f-a5bb-29bb485d427a","http://resolver.tudelft.nl/uuid:acd7e4f7-849b-400f-a5bb-29bb485d427a","Change detection and deformation analysis using Terrestrial Laser Scanning: Case study of the metro tunnel at Rotterdam central station","Van Goor, B.","Hanssen, R.F. (mentor); Lindenbergh, R.C. (mentor); Soudarissanane, S.S. (mentor)","2011","A Terrestrial Laser Scanner (TLS) is a powerful tool for surveying. Tens of millions of points are acquired with a high accuracy and within a short time. The resulting point clouds can be used to find changes and deformations. For this project, four point clouds of the metro station and tunnel at Rotterdam central station are available. The processing of the Laser Scanning data can be a time consuming task. Depending on the desired end product, various steps are required. During this graduation project, a method is proposed to find changes and deformation in the repeated TLS point clouds. A key step in this method is to distinguish surfaces in the point clouds that are changed from unchanged surfaces. The unchanged surfaces are investigated in more detail to find deformations in the Signal-to-Noise Ratio. The proposed method consists of three processing steps. The first step is to transform all the scans to the same (absolute) coordinate system. The second step is to divide the point clouds in segments. These segments are planar surfaces in the metro tunnel. During the segmentation matching, corresponding surfaces sampled at two different moments are identified, which is the third step. These matching segments are compared in more details during a deformation analysis. Segments without a match are subject to a change detection. The proposed method is applied to three case studies, using real data from the metro tunnel. The first case demonstrates the use of the method to research the registration accuracy and find occlusions between two scans. The two other cases demonstrate the change detection and deformation analysis. The results are validated using total station and joint meter measurements.","terrestrial laser scanning; change detection; deformation analysis; Rotterdam metro tunnel","en","master thesis","","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","Geomatics","",""
"uuid:1437f2fc-b07b-4a5d-8656-22a64a23fb69","http://resolver.tudelft.nl/uuid:1437f2fc-b07b-4a5d-8656-22a64a23fb69","The development of an optimization procedure for the drivetrain of large-scale offshore wind turbines","Daneels, J.","","2013","","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6a4f1673-88b1-4823-b2ef-9d864c84ab11","http://resolver.tudelft.nl/uuid:6a4f1673-88b1-4823-b2ef-9d864c84ab11","A Hodographic-Shaping Method for Low-Thrust Trajectory Design","Gondelach, D.","Noomen, R. (mentor)","2012","The goal of this research was to develop an analytic low-thrust trajectory design method. The term low thrust stems form the fact that current electric propulsion systems can only produce low amounts of thrust. Nevertheless, these systems can deliver very high amounts of ?V using little propellant, which makes them very suitable for interplanetary flight. The orbital mechanics regarding low-thrust interplanetary flight were considered and it was found that for first-order design it is acceptable to neglect all perturbing forces with respect to the Sun's gravitational attraction and the (low) thrust force. In addition to that, a look was taken at the characteristics of electric propulsion and feasible thrust (acceleration) levels were obtained. Since only low thrust levels can be achieved by electric propulsion, long periods of thrusting are required to obtain sufficient change in velocity. This continuous thrusting feature of electrically-propelled spacecraft highly complicates the dynamics of such spacecraft. As a consequence, the design and optimization of low-thrust trajectories is very difficult, and therefore preliminary design of such trajectories is very important. Such first-order designs can give a fast overview of all feasible trajectories and can, moreover, be used as an initial guess for more refined trajectory optimization. For generating and optimizing first-order low-thrust trajectories, analytical methods are very suited, since they are very fast and exact. Several analytical low-thrust methods have been developed recently and most of them are shape-based; the trajectory is assumed to have a specific shape which satisfies the boundary conditions and subsequently the thrust profile can be obtained from the dynamics. These shape-based methods are popular for preliminary design, because of their simplicity and ability to obtain feasible trajectories. The currently known shape-based methods were investigated to obtain know-how about their functioning and to find their strengths and weaknesses. It was noticed that regarding the solving of boundary conditions improvements could be made and that most shaping methods lack flexibility. Inspired by the use of velocity hodographs for the computation of non-perturbed transfer orbits, a novel low-thrust trajectory design method was developed based on shaping the velocity of spacecraft during the transfer. For the shaping of the velocity components, velocity functions were used which consist of a sum of simple base functions. These base functions can be integrated analytically, such that the change in position can be obtained analytically. Since the velocity is shaped, the conditions on initial and final velocity can be solved very easily and exactly. In addition, the boundary conditions on position can be solved exactly without the need of iterative computations. Next to the parameters required to satisfy the boundary conditions, extra parameters can be added to make the design and optimization of trajectories more flexible. Two different methods have been developed; one which shapes the velocity as a function of time and another one which shapes as a function of the polar angle. For the computation of the required ?V , and for the computation of the polar angle in the time-driven method, numerical integration is required. Four simple integration methods were tested and an RK4 integrator was found to perform best based on accuracy and computation speed. Since the derivative of the ?V and the polar angle (the thrust acceleration and angular velocity, respectively) can be computed as a function of time or polar angle, their values can be computed prior to the integration. As a result, RK4 integration simplifies to Simpson's rule and the integration can be done much faster. Both hodographic-shaping methods have been verified by numerically propagating the initial spacecraft state vector using thrust profiles found by the shaping methods. Both the time-driven and polar-angle-driven method were found to function well, and the obtained trajectories and thrust profiles agreed almost exactly. In order to obtain minimum-?V trajectories, the free parameters in the velocity functions were optimized. Both a Nelder-Mead (NM) and Differential Evolution (DE) optimizer were tested for this purpose. NM was found to be equally robust, but much faster than DE, and therefore NM was used. In addition, initial guesses for the free parameters were used to speed up the optimization. Finally, the search for the optimal departure date and TOF was done by stepping through the flight window using a grid. Both hodographic-shaping methods were tested for missions to Mars, the near-Earth asteroid 1989ML, comet Tempel 1 and Mercury. For missions to Mars and 1989ML the two methods gave comparable results. The time-driven method found better trajectories to Tempel 1 (a far outer target), whereas the polar-angle-driven method found better ones to Mercury (an inner target). In comparison with the spherical and pseudo-equinoctial shaping methods and DITAN (the benchmark), the hodographic-shaping methods performed well, especially for mission to Mars and to asteroid 1989ML. The near-optimal results came at the cost of computational speed. The best results were found using 6 free parameters requiring require a computation time of 2 s per trajectory on average. The lowest-order solutions (0 DoF), on the other hand, required only 1.6 ms per trajectory on average. Finally, the lowest-order solutions were found to be unable to obtain near-optimal trajectories, however, they were able to indicate the correct regions of low ?V in the flight windows and to give a good indication of the required ?V and thrust acceleration.","shape-based method; low-thrust transfer; orbital mechanics","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","Astrodynamics and Space Missions","",""
"uuid:df9e2dc4-b9eb-435d-ab43-3590aad8888e","http://resolver.tudelft.nl/uuid:df9e2dc4-b9eb-435d-ab43-3590aad8888e","Particulate Polymer Foam Composites: For Piezoelectric Sensing Applications","De Boom, K.","Groen, W.A. (mentor); Van der Zwaag, S. (mentor); Khanbareh, H. (mentor)","2016","In recent years the number of applications relying on piezoelectric sensors has increased rapidly. New applications lead to new requirements concerning material properties and functionalities. In many of the (future) applications, such as artificial robotic skin, structural health monitoring and flexible keyboards, the necessity for flexibility and conformability of the sensor material is evident. The sensor material should be able to nicely follow the surface of complex shapes and sensing efficiency should be enhanced further. Therefore, the main goal of this project was to reduce the dielectric constant and improve flexibility and conformability of traditional di-phase flexible piezocomposites consisting of PZT particles in a dense polymeric matrix, by adding a third (gaseous) phase to the system. The presence of the gaseous component in the polymer matrix lowers its dielectric constant and increases the piezoelectric voltage constant, g33, which is the scalar measure for the touch sensitivity of the system. The focus of the optimisation in this project is on the polymer matrix phase and the (micro)structure of the particulate polymer foam composite. Lead Zirconium Titanate (PZT) with composition Pb(Zr0.52 Ti0.4)O3 was selected as the piezoceramic filler phase. Elastomeric Polyurethane (PU) was found to be the most optimal polymer matrix system, showing excellent flexibility, conformability, viscosity behaviour upon curing and processability. Another advantage of the selected PU system is the large operating temperature range, which was found to be between 0 ?C and 160 ?C. Furthermore, component A (diisocyanates) of the PU system is able to react with water, resulting in the release of CO2. Thereby the gaseous volume fraction of the foam could be fine-tuned and increased significantly. For open-mould production processes (0-3 random composites), adding 0.4 vol% demineralised water (microliter-range) to the system resulted in gaseous volume fractions of >55%, whereas closed-mould production processes (1-3 quasi-structured composites) required only 0.2 vol% demineralised water to obtain similar porosity. This indicates that approximately 50% of the total amount of CO2 formed, escapes the system in an open-mould approach. The reduction in dielectric constant was found to be proportional to the increase in gaseous volume fraction. The PZT-PU foam composites showed remarkably high g33 values up to maximum values of 95 mV.m/N for unstructured 40%PZT-PU foam and 170 mV.m/N for quasi-structured 10%PZT-PU foam, primarily resulted from the significant reduction of the dielectric constant. Note that the volume fraction of piezoceramic loading has to be corrected for the increase in total volume due to the addition of the gaseous phase. The best performing composite (1-3 10%PZT-PU) has a corrected volumetric composition of: 4.3%PZT - 39.1%PU - 56.6%air. The great performance of the new concept opens up routes for further improvement of porous piezoelectric composites and we are now one step closer to the realisation of the material that meets the (future) requirements for flexible piezoelectric sensors.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","Novel Aerospace Materials Group - Smart Materials Team","",""
"uuid:f2fcf3f0-dfc5-4a75-aab3-cffc2e1ad348","http://resolver.tudelft.nl/uuid:f2fcf3f0-dfc5-4a75-aab3-cffc2e1ad348","Cost Effective Attitude Control Validation Test Methods for CubeSats Applied to PolarCube","Clarke, M.A.H.","Guo, J. (mentor)","2016","The problem of testing the performance of an attitude control system presents new challenges and opportunities when conducted on a CubeSat scale. This is the result of drastic reduction in physical properties (size, mass, torques) as well as project resources (funds, manpower, time) when compared to traditional satellite programs. This thesis presents an analysis of the problem of validating active attitude control of a CubeSat before launch and a proposed methodology that is demonstrated on the Colorado Space Grant Consortium’s PolarCube satellite. In order for an attitude control system’s performance to be measured, it must be provided with a physical environment that allows the system to act similarly to how it would in orbit and its behavior must be recorded in such a way that metrics of performance can be derived. To date, published tests of this nature on CubeSats have been limited in their precision due to uncertainty in external torques on the attitude control system and have mostly been conducted on commercially available attitude control system modules. A string suspension testbed was chosen to provide a simulation of microgravity that allows the system to rotate free of friction. This thesis builds on the practices for string suspension testing developed for the MicroMAS CubeSat mission in which a ""fit-predict-fit"" method of producing metrics of attitude control system performance was first implemented for CubeSats. The project set out to identify and solve points of failure that were limiting measurement performance of the tests conducted on the MicroMAS system and ultimately produce more accurate measurements and predictions of testbed and attitude control system dynamic response. An engineering model of the satellite bus was designed and built to provide independent power, wireless communication and data handling to the attitude determination and control subsystem. An attitude determination method was developed using MEMS magnetometers, accelerometers and rate gyroscopes to operate within a laboratory environment. A model of the dynamics of the test model’s behavior in the testbed was created to generate predictions of the test model’s response to test conditions, act as a platform to compare measured and expected test results, and verify the attitude determination method. Attitude determination performance was determined through a combination of direct testing and dynamics modeling in software. The methods found a maximum (worst case scenario) heading determination error of 4.6 ? after feed-forward correction based on characterization tests. Oscillation tests were used to determine the external torque properties of the string suspension testbed to within two significant figures, a drastic improvement in performance compared to the MicroMAS test results. Less than $300 were spent on hardware dedicated to testing. The overall system is marked by its simplicity and cost-effectiveness. The results will render attitude control validation testing and consequently the use of active attitude control more accessible to future CubeSat missions. Improvements in performance when compared to the MicroMAS test results were identified as the result of more robust and flexible software modelling of string suspension testbed dynamics, improved methods of characterizing testbed external torque properties as well as improved attitude determination performance.","attitude; control; CubeSat; string; test; hardware in the loop; determination; testbed; method; microgravity; simulation; validation; XBee; Arduino; PolarCube; Space Grant; TU; Delft; Boulder; pointing; magnetometer; imu; system; ALL-STAR; COSGC; nanosatellite; satellite; reaction wheel","en","master thesis","","","","","","","","","Aerospace Engineering","Spaceflight","","Space Engineering","",""
"uuid:4b95f124-7ea5-49ea-af65-dfb436d6bdc7","http://resolver.tudelft.nl/uuid:4b95f124-7ea5-49ea-af65-dfb436d6bdc7","Bats in Gliding Flight: A comparative wind tunnel investigation of the aerodynamics of gliding bats and a bat inspired gliding wing model","Stuiver, M.","Bijl, H. (mentor); van Oudheusden, B.W. (mentor); Muijres, F.T. (mentor); Remes, B.D.W. (mentor)","2011","Due to the high cost of flight, there is a high evolutionary selection pressure for energy efficient flight patterns, such as using external natural forces for soaring or flying intermittently. Some bats at time soar, glide or flap glide. Bounding flight is not possible as their membranous wings will go slack, and soaring is not common amongst bats, as most bats are nocturnal and during night thermals are usually of insufficient strength. From an aerodynamic point of view, gliding flight is less complex than flapping flight, however in bats undulating flight patterns are less observed than in birds. So, why should bats glide? Flight performance studies on live bats have revealed a part of the complexity of hovering and steady flapping flight, but gliding flight in these animals is poorly studied. To get insight in how bats glide and in their gliding flight performance, gliding flight of bats is studied from two points of view; gliding flight of real bats and gliding of a flexible, bat inspired wing model, in a low speed, tiltable wind tunnel. The kinematics of both the bats and the model are filmed by two synchronised high speed cameras, and the flow field in a transverse plane behind the wings is visualized by means of a PIV system. Three medium sized bats Leptonycteris yerbabuenae, are trained to glide at a feeder in the test section of the wind tunnel at a know, fixed glide angle. This known glide angle enables to calculate the aerodynamic forces, which are fixed properties in steady gliding flight. A gliding wing model, based on a bat’s wing, with an adjustable leading edge flap, is designed, build, and tested at different angles of attack. The wing model is tested with both a smooth and a structured top surface to see what the effect of ’turbulators’ can be. Additionally the wing model is mounted onto a balance in order to measure the aerodynamic forces. By means of experiments with the wing model, wake structures of gliding flight can be connected to a single changing morphology parameter to explore the parameter space, and the wake structures can be compared to the wake structures of the gliding bats. The bats are observed to glide for some seconds in the test section, but only the parts of the glides at the feeder where the tip vortex strength and position were stable are analysed. From the PIV data, an average wake is constructed per glide sequence of the bats, and for each leading edge setting and speed combination of the model wing. From the average wake the flight forces and the resulting flight performance properties are derived. The wing model approaches the glide behaviour of the bats. Deploying the leading edge flap increases the span efficiency and the lift coefficient at low angles of attack. Also the structure on top of the wing is beneficial for flight performance at low angles of attack.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b71d978d-7360-49e0-81bd-2af9b751a9e0","http://resolver.tudelft.nl/uuid:b71d978d-7360-49e0-81bd-2af9b751a9e0","Evaluation of the ESReDA Cube Method for the Aviation Sector","Martens, F.J.L.G.","Melkert, J.A. (mentor)","2015","Nowadays accident analysis tools focus on finding the cause of an accident so that lessons can be learned. The ESReDA Cube method is designed to explore a new field in accident analyses. It focuses on the next step, namely analysing the lessons learned out of an accident. It is checked if they are sufficient and if they caused any change(s). With this project the ESReDA Cube method will be evaluated for the first time for the aviation sector. The ESReDA Cube analysis is performed in several steps. First the accident is described. Next a three dimensional overview of the lessons learned is created. This overview, in the shape of a cube, is called the ESReDA Cube. The three dimensions the method explores are: operation level, system level and depth of learning level. To make the overview three questions are asked for every lesson learned. Every question is related to a specific dimension: Operation level: “What needs be learned?” (content, structure, culture, context) System level: “Who should learn?” (micro, meso, macro) Depth of learning level: “How to learn?” (optimize, adapt, innovate) Behind every question, the available answers are presented between parentheses. The three answers represent a lesson learned as a set of three dimensional coordinates. In this way every lesson learned can be located in a specific part of the ESReDA Cube and an overview is created. Using this overview it can be analysed where exactly lessons are learned. By checking the spreading of the items over the cube it is checked if there is still learning potential somewhere. It is also possible to combine the results of several cases into one cube to analyse multiple cases together. The next step is to describe the impact of the lessons learned to check if something changed or if any implementation problems are encountered. With the results obtained conclusions can be drawn and if necessary new learning suggestions can be issued. In this thesis the method is applied on three accident cases. The three analysed cases all have stall as a contributing factor, and due to that they are quite similar. The cases chosen are: Air France flight 447 Colgan Air, Continental Connection flight 3407 Turkish Airlines flight 1951 The cases are analysed both individually as well as together. The results show that the part of innovation on the depth of learning level is quite empty, which can indicate learning potential. Although new concepts to prevent stall accidents exist, they are not recommended. All lessons on the depth of learning level are learned in the part of adaptation and optimization. Stall accidents still occurred after these three accidents, which confirms that maybe other lessons should be learned instead of always optimizing and adapting. It can be concluded that more research should be done for new innovative concepts to prevent stall accidents. By applying the method on three cases it is seen that in the current method’s state and usage, problems are encountered which prevent a complete analysis. Only one level can be completely analysed, namely the depth of learning level. At the operation level no complete analysis is possible due to lack of input with only public sources and due to an insufficient lay-out. At the system level also no complete analysis is possible due to an insufficient lay-out of the meso and macro part. These problems cause the method to almost always obtain the same results, namely an empty aspect of innovation. Due to this the method is in its current state and usage not applicable for the aviation sector. It is recommended to change the lay-out of the operation and system level. Another recommendation is to change the target group of the method to investigators/instances with access to more than only public sources, like companies or safety agencies. To check if the new lay-out and target group make the method applicable for aviation further evaluation is recommended.","ESReDA Cube; ESReDA","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration & Operations","","Systems Engineering and Aircraft Design","",""
"uuid:5148aafa-91ed-485d-ac7a-2883394ec0a4","http://resolver.tudelft.nl/uuid:5148aafa-91ed-485d-ac7a-2883394ec0a4","Hybrid Electric Propulsion Systems: Integrated performance analysis applied on short-range aircraft","Ang, A.W.X.","Gangoli Rao, A. (mentor)","2016","The growing level of environmental implications of aviation and a significant increase in air traffic have been driving technological advancements in the aerospace industry. The rising developments in battery technology allowed the automotive industry to build hybrid and fully electric cars. However, the limited power-to-weight ratio components impede the development of fully electric aircrafts. In this regard, Hybrid Electric Propulsion Systems (HEPS) are more viable. With HEPS, the aero-engine is combined with an electric system. This brings several technological challenges, such as the increased complexity in the performance and sizing methodology of the propulsion system and the necessary offset of the weight increment. Because of these issues, the different state of the art HEPS concepts largely depend on the development of new technologies, as well as maintaining efficient power management during the different phases of the flight envelope. The power management system adjusts the supplied power ratio between the energy sources during operation, as power can come from fuel and/or electrical energy. The objective of this study is to analyse the power management of HEPS, focusing on passenger transport aircraft. The application of HEPS in the mid/long-term is heavily dependent on the technology maturity level of electric components. To examine the performance of HEPS, a simulation model is developed after determining the power requirements of a flight mission. The effects of different power management control strategies are analysed by combining different take-off and climb power splits. The power management control strategy with a take-off and climb power split of approximately 25% and 14% respectively, while scaling down the engine to 90%, is the most optimal and feasible strategy. This will reduce the fuel burn by 7.5% and total energy consumption by 2%.","power management strategy; performance sizing; Hybrid Electric Propulsion System; HEPS","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:7656ca5b-8904-4551-9fde-dcf92573c6d3","http://resolver.tudelft.nl/uuid:7656ca5b-8904-4551-9fde-dcf92573c6d3","Aviate, Navigate: Functional Visualizations of Asymmetric Flight Envelope Limits","Rijndorp, A.D.T.","Borst, C. (mentor)","2016","Current aircraft flight deck interfaces do not provide information on how a performance-altering failure constrains the aircraft's flight envelope. As a result, it is difficult for flight crews to plan an emergency landing trajectory. This study presents the results of the conceptual development of novel constraint-based interface symbology that aims to solve this issue. As no fully functional on-line flight envelope prediction system implementations currently exist, a simplified dynamical model with an asymmetric flight envelope was developed to overcome this limitation. The proposed interface symbology integrates with the existing primary flight display and navigation display. A human-in-the-loop experiment was conducted to validate the effectiveness of the used symbology. The results lend credibility to the belief that presenting flight envelope constraints in terms of reachable navigation states may improve short-term tactical planning and reduce the pilot's mental workload during emergency situations.","navigation; cognitive systems engineering; interface design; avionics; decision making; flight envelope","en","master thesis","","","","","","","","2018-05-13","Aerospace Engineering","Control & Operations","","","",""
"uuid:f5819979-5874-497d-9ec5-8645916b9c9a","http://resolver.tudelft.nl/uuid:f5819979-5874-497d-9ec5-8645916b9c9a","Maximum Likelihood Estimation of Linear Time-Varying Pilot-Vehicle System Parameters","Kers, M.","Mulder, M. (mentor); Pool, D.M. (mentor); Van Paassen, M.M. (mentor); Chu, Q.P. (mentor)","2012","","Maximum Likelihood Estimation; Human-Machine Interaction; HMI; aerospace; system identification; parameter estimation; Gauss-Newton; Boltzmann Sigmoid; control; simulation; modeling; LTV; Linear Time-Varying; MLE","en","master thesis","","","","","","","","2016-06-01","Aerospace Engineering","Control & Operations","","Human-Machine Interaction","",""
"uuid:4d22ccdd-f4e7-458e-b455-7405eaba6245","http://resolver.tudelft.nl/uuid:4d22ccdd-f4e7-458e-b455-7405eaba6245","Topology optimization of 3D linkages with application to morphing winglets","De Jong, T.A.","De Breuker, R. (mentor); Gillebaart, E. (mentor)","2016","Topology optimization is the process of optimizing both the material layout and the connectivity inside a design domain. The first paper on topology optimization dates back to 1904, when the Australian inventor Michell derived optimality criteria for minimum weight truss structures. In 1988 Bendsøe and Kikuchi published the pioneering paper ""Homogenization approach to topology optimization"", laying the foundation of numerical optimization methods for topology optimization. Since then, extensive research has been performed both in academia and industry trying to solve different topology optimization problems. Due to its general applicability, topology optimization has been applied to the design of many morphing aircraft structures including morphing leading edges, trailing edges, or both. It has also been applied to complete morphing wings. Morphing structures have the ability to change their shape throughout the flight. This allows for possible weight savings and/or drag reduction, resulting in a reduced fuel consumption. Despite the great interest in morphing winglets from both Airbus and Boeing, topology optimization has not yet been used to design morphing winglets, except for previous work done by E. Gillebaart and R. De Breuker. This thesis continues with the research by focusing on the following research objective: ""Developing a software tool to design amechanism for morphing winglets, using ground-structure based topology optimization, by improving, extending, and expanding the previous 2D inhouse tool."" The research in this thesis is based on previous work done by the faculty. The previous 2D tool is improved, its capabilities are extended and the tool is expanded to 3D. The current tool effectively demonstrates how topology optimization, based on the ground-structure approach, can be used to obtainmechanisms for morphing winglets. A two step optimization strategy is formulated, where the mechanism is designed in the first step and sized to obtain minimum weight in the second step. Both optimizations are done using the globally convergent method of moving asymptotes (GCMMA) optimizer, combined with the adjoint sensitivity technique. Due to the large rotations of the winglet, geometric non-linearity is taken into account using the Green-Lagrange strain measure. Various mechanisms for morphing winglets were successfully designed and sized both in 2D and in 3D. In 2D mechanisms were found where the cant angle could be regulated, in 3D mechanisms were found where both the cant angle and the toe angle could be regulated. An aerodynamic load case of 5 [kN] was defined. In 2D half of this loading was assumed to act on the mechanism, resulting in a minimum weight of 15.0 [kg]. In 3D the minimum weight was found to be 48.0 [kg].","topology optimization; Green-Lagrange; geometric non-linearity; optimization; GCMMA; morphing; morphing winglet","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","Aerospace Structures and Computational Mechanics","",""
"uuid:d4c70a99-0c87-4862-a542-24dfc778e684","http://resolver.tudelft.nl/uuid:d4c70a99-0c87-4862-a542-24dfc778e684","Online non-destructive evaluation in automated fibre placement","Tonnaer, R.","Shroff, S.C. (mentor)","2016","The strict quality requirements for aerospace composite structures give rise to costly quality control procedures. In automated fibre placement (AFP) these procedures rely heavily on manualwork and inspection. This research aims at performing preventative non-destructive evaluation of composite laminate quality based on an online geometric analysis of the placed fibre. A robot mounted laser pro le sensor, in combination with robot positional data, is used to create a 3D model of the fibre. These are fused using quaternion coordinate transfer operations with the Robot Operating System, an open source robotics platform. The 3D model is converted into an image for fast processing using open source algorithms from OpenCV. Deviations in part-product quality are identified in real-time including geometric, positioning and buckling defects due to high-radius curvatures in the fibre path. Currently the prototype system will give a non-conformance warning to the operator, and in future work it is planned to develop automated feedback and control algorithms to correct common de fects. The implementation of a preventitive system in an industrial fibre placement process can cut back the time spent on inspection and rework.","automated fibre placement; non destructive evaluation; non destructive testing; Robot Operating System; qualtiy control; in process; online; preventative; laminate quality; composites","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","Structural Integrity and Composites","",""
"uuid:ab2c5059-bc27-4dab-afe0-91dec347d967","http://resolver.tudelft.nl/uuid:ab2c5059-bc27-4dab-afe0-91dec347d967","A multi-agent operational planning model for airport stakeholders: using capacity forecasts in winter scenarios","Borst, J.A.P.","Roling, P.C. (mentor); Visser, H.G. (mentor); Hesselink, H.H. (mentor)","2017","","Multi-agent system; Airport operational planning; Collaborative planning; Principled negotiation; Amsterdam Airport Schiphol; Winter","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Air Transport & Operations (ATO)","",""
"uuid:ed8f6b15-00b5-460d-b3eb-575ee537b05d","http://resolver.tudelft.nl/uuid:ed8f6b15-00b5-460d-b3eb-575ee537b05d","Fishing on Europe: Dynamics of the Jovian moon and its subsurface ocean","Huibregtse, J.N.","Vermeersen, L.L.A. (mentor); Van Leeuwen, P.J. (mentor)","2008","The interior of Europa, one of the moons in the Jovian system, is still mainly unknown. There are, however, indications that below an icy outer layer a subsurface ocean is present. Moreover, it has been estimated that in total the ice and ocean are between 80 and 170 kilometers thick. Concerning the thickness of the ice layer, there exist two hypotheses: some believe this layer is relatively thin (up to approximately ten kilometers), whereas others think the ice layer will be much thicker. Since it is expected that the global deformation rate of Europa, caused by the gravity pull of Jupiter, gives insight in the interior of this moon, it is of great interest to investigate this by means of computational models. The main question to be answered in this thesis is: how does the subsurface ocean of Europa deform, due to the tidal pull of Jupiter? To answer this question, the tidal forcing by Jupiter is determined. This tidal potential can be subdivided in a constant tidal potential and a time varying part. Only the latter results in an exchange in tidal energy and time-varying deformation and is, therefore, of interest. The global deformation of Europa due to this time-varying forcing is studied by means of the normal mode analysis. For this analysis, it is assumed that Europa consists of four coupled homogeneous layers; the core, the mantle, the ocean and the sea ice layer. From the normal mode analysis it followed that the radial deformation of Europa in the absence of an ocean, is less than one meter, whereas this deformation is approximately 20 meters if an ocean is present. From these results it can be concluded that by measuring the actual global deformation, for instance by means of future satellite measurements, the presence of an ocean can be determined. The next step is to model the ocean by means of the MIT General Circulation Model (MITgcm), a model that was originally developed for Earth. In this model, the ocean is no longer assumed to be homogeneous. Without sea ice, an ocean of 100 kilometers deep radially deforms approximately 20 meters due to the time-varying tidal potential. In case of an ocean with a depth of 100 kilometers and a sea ice layer with a thickness of ten kilometers, the Europan surface still radially deforms approximately 20 meters, from which it follows that the sea ice layer does not reduce the ocean deformation, i.e. the sea ice acts fluidly. This was also obtained from the normal mode analysis. Furthermore, it follows that the tidal forcing disturbs the geostrophic balance in the ocean and that the ocean dynamics, due to the tidal forcing are driven by the vertical velocities. Since the mantle is also subject to tidal deformation, heat will also be generated in this layer. On Io, for instance, volcanoes are present and it is therefore reasonable to assume that volcanoes are also present on the ocean floor of Europa. These volcanoes release the tidal heat from the mantle in the ocean. Consequently, the sea ice experiences extra heating, which leads to additional melting. This may be a strong argument for the thin sea ice hypothesis. In addition, it is shown that the shallower the ocean, the higher the ocean velocities. Thus, the presence of subsurface volcanoes and, for example, ridges will locally result in higher ocean velocities. It may well be the case that these disturbances in the velocity field and the heat released by volcanoes result in melt troughs and produce the characteristic cracks visible on the Europan surface.","Jovian moon; ocean dynamics; tidal motion","en","master thesis","TU Delft, Aerospace Engineering, Astrodynamics and Satellite Systems","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4c1fee72-e90d-444b-b702-772ebfe41073","http://resolver.tudelft.nl/uuid:4c1fee72-e90d-444b-b702-772ebfe41073","Study on aerodynamic imbalance of wind turbine rotors: An investigation of effects due to blade pitch assymetry.","Xiomara Herrera Feregrino, X.H.F.","Nando Timmer, N.T. (mentor)","2015","","Windenergy; rotor aerodynamic imbalance","en","master thesis","","","","","","","","2015-10-08","Aerospace Engineering","Wind Energy","","EWEM","",""
"uuid:f9006265-0971-47d3-816d-dc58ca03eb84","http://resolver.tudelft.nl/uuid:f9006265-0971-47d3-816d-dc58ca03eb84","Vortex decay behind a generic wing-flap-jet aircraft model: A time dependent vortex model","de Kat, R.","Veldhuis, L.L.M. (mentor)","2007","The safety threat posed by vortex wake encounters acts as a limiting factor in meeting the growing demand for airport capacity. To gain more insight in the governing processes in aircraft wakes fundamental research on the formation, persistence and decay of the wake behind aircraft is performed within the EU-funded FAR-Wake project. As part of this project we experimentally determined the influence of a cold jet on the wake behind a wing-flap model -resembling an aircraft in landing/take-off configuration-. The application of a traversing-FOV stereo-PIV system in the TU Delft towing tank leads to an accurate determination of the complete velocity field in a plane perpendicular to the ’flight’ direction for large distance behind the model (up to 100 wing spans).","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:832aa36d-041b-4896-97a7-837f91cdc5d6","http://resolver.tudelft.nl/uuid:832aa36d-041b-4896-97a7-837f91cdc5d6","Design Optimization of Ground and Air-Launched Hybrid Rockets","Miranda, F.","Zandbergen, B.T.C. (mentor); Dirkx, D. (mentor)","2015","Access to space is now more important than ever. For the last few years, smaller and smaller satellites are acquiring the capacity to do what was previously only possible with large platforms. Currently, most small countries can build a small satellite, but most cannot afford to launch one by themselves. Air launching rocket vehicles has been touted as a possible solution to reduce the cost of both the launch vehicle and its operation, especially for the launch of small payloads. Most research in the field looks into solid rockets, here, however, hybrids are investigated. Hybrid rocket vehicles work by burning solid fuel with liquid oxidizer. Unlike solid rockets, hybrids can be re-ignited, are safer, and have a potentially higher orbital injection accuracy and specific impulse. To study the feasibility and performance of such a solution, a Multidisciplinary Design Optimization tool was used. The tool is an improvement upon a previous software package that only supported solid rocket technology. It addresses trajectory computation, estimation of vehicle dimensions and propulsion performance and launch simulation. The tool was developed in C++, and is now capable of handling multi-stage solid-only rockets, hybrid-only rockets and mixed configurations. It consists of performance and dimension estimators for individual rocket stages, these are integrated into a launch vehicle whose launch is simulated and analysed. The tool has been used to optimize the configuration of a rocket vehicle designed to attain a circular orbit (eccentricity < 0.01) at 780 km altitude. By iterating on the design using an optimization process known as Particle Swarm Optimization, it attempts to reduce the take-off weight of its solutions. The tests allow one to compare hybrid propellant rockets to solid ones in both air and ground launched scenarios. Based on the assumptions made, it was found that air-launch reduces GTOW by about 70 % when compared to an equivalent ground launch. It is also found that, in general, hybrid rockets have a GTOW similar to, or higher than, their solid counterparts. The research also tackles whether mixed configurations (with both solid and hybrid stages) allow one technology to strengthen the other. Results are also shown on the launch performance of existing engines, to both validate the models and offer insight to manufacturers into how their vehicles will perform once launched.","hybrid rockets; air launch; design optimization","en","master thesis","","","","","","","","","Aerospace Engineering","Space Systems Engineering","","","",""
"uuid:bd25768c-48b2-42df-826e-82129d2ad9f6","http://resolver.tudelft.nl/uuid:bd25768c-48b2-42df-826e-82129d2ad9f6","Tidal deformation of Europa and Phobos: Implications on their structure and history","Kleuskens, M.H.P.","Vermeersen, L.L.A. (mentor)","2006","","icy moon europa; tidal deformation; phobos","en","master thesis","TU Delft, Aerospace Engineering, Astrodynamics and Satellite Systems","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d19d75c1-e328-4128-853c-48177a5abaf4","http://resolver.tudelft.nl/uuid:d19d75c1-e328-4128-853c-48177a5abaf4","Development of a wind farm power forecast model","Janssen, J.","van Bussel, G.J.W. (mentor); Bierbooms, W.A.A.M. (mentor); Malda, D. (mentor); van den Brink, H. (mentor)","2012","","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0c0e4624-7c4c-4eb5-8f0a-2334089d56e2","http://resolver.tudelft.nl/uuid:0c0e4624-7c4c-4eb5-8f0a-2334089d56e2","Constrained Lunar Density Inversions","Heijkoop, E.","van der Wal, W. (mentor)","2017","This thesis presents the results of a developed density inversion tool, which estimates lunar crustal density anomalies from Bouguer anomalies. The tool is run through a number of tests for verification, culminating in the forward modeling and subsequent inversion of synthetic density anomalies, showing a > 97% recovery of the original density anomalies. The density inversion is applied to a number of lunar regions. The region containing the landing sites of the Apollo 12 & 14 missions is selected first. The results of this region are consistent with returned samples, providing validation of the inversion. Next, Mare Crisium and Mare Orientale are selected, to give insight into the formation of melt sheets after impacts and subsequent mantle upwelling to achieve isostatic equilibrium. To do this, the tool was expanded to estimate multiple layers of density anomalies, which required constraining with the help of a priori information, which itself was in part derived from lunar seismology. Such constraining is necessary to remove the non-uniqueness inherent in inversion. The results show that Mare Crisium still contains a thin sheet of several (4 to 6) km thickness on the crater floor, showing that mantle upwelling has not reached the surface. For Mare Orientale a melt sheet of higher density than the surrounding crust (2650 kg m−3 vs 2550 kg m−3 ) is found with a thickness consistent with Zuber et al. [2016] (10 km). If this higher density is not present, the melt sheet is thinner than that proposed by Zuber et al. [2016] (6 km vs 8 km), thus showing a slight mismatch in consistency between normal and raised density for the melt sheet.","Gravimetry; Inversion; Moon; Planetary Science","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","Astrodynamics & Space Missions","",""
"uuid:3a061451-78d2-4a22-922f-0116ca6662ea","http://resolver.tudelft.nl/uuid:3a061451-78d2-4a22-922f-0116ca6662ea","Analysis of Skill Development in Manual Ramp Tracking Tasks: Using a Feedforward Pilot Model","Willems, M.E.","Mulder, M. (mentor); Pool, D.M. (mentor); Van Paassen, M.M. (mentor); Damveld, H.J. (mentor)","2012","A study is performed analyzing the behavioral adaptation of pilots in skill based ramp tracking tasks performed with pursuit display. From data analyses of previous ramp tracking experiments an indication is found that pilots who repeatedly perform the same ramp tracking task show a high level of adaptation to characteristics of the control task in their behavior. From the theory of Successive Organization of Perception it is expected that this development progresses towards precognitive behavior. To get to a better understanding of the transition between pursuit behavior and precognitive behavior, a pursuit ramp tracking and disturbance rejection experiment is performed to further study this. For this four conditions with a different ramp steepness are used in blocks of ten runs, with eight similar ramps in each run. Two sessions are performed, one ordered session where the same condition is performed ten times consecutively and a random session, where conditions are presented in random order. After each block of ten ordered runs also a surprise run with a different condition is presented. The behavior is analyzed using performance metrics and by performing a time-domain parametric identification of a combined compensatory and feedforward pilot model. The behavior is analyzed in three ways: first by using the averaged data of the final five runs as steady-state behavior, then by using the data per run to investigate the development over the runs and finally the data per ramp is analyzed to investigate developments within a run. The surprise runs are analyzed over the entire run and per ramp. From performance and behavioral metrics no difference in ramp tracking behavior is shown when conditions are presented consecutively as opposed to randomly. From the model parameters though, it was found that the difference in behavior is predominantly visible in the feedforward pilot gain, and it is shown that the difference in behavior is mostly apparent in the first ramps of each tracking run. After the first two ramps, the pilots are found to already have adjusted their behavior towards their optimal control setting. From the surprise runs strong indications were found that pilots need more time to adjust after being conditioned in the previous ten runs to a different condition. This suggests that pilots use precognitive control strategies when they are more experienced in the task performed and think they know what to expect. Novel research should be performed to extend existing pilot models by modeling precognitive pilot behavior","Control; Simulation; Human Machine Interaction; HMI; Modeling; Skill Development; feedforward; Skill","en","master thesis","","","","","","","","2016-06-01","Aerospace Engineering","Control and Simulation","","Human Machine Interaction","",""
"uuid:1b67b37a-1c7c-4f8e-ab43-1fa441d3244c","http://resolver.tudelft.nl/uuid:1b67b37a-1c7c-4f8e-ab43-1fa441d3244c","Boundary Layer Suction on a Horizontal Axis Wind Turbine: An Aerodynamic Design of a Thick Airfoil for Application","Zwang, L.","van Bussel, G.J.W. (mentor); Barlas, A. (mentor); Terry, E. (mentor); Hulskamp, A.W. (mentor); Timmer, W.A. (mentor)","2009","","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:88b7b720-7402-4e1a-85e6-7dc785a23b16","http://resolver.tudelft.nl/uuid:88b7b720-7402-4e1a-85e6-7dc785a23b16","Internal flow of fluidic oscillators: A numerical and experimental investigation","Sitter, M.","Kotsonis, M. (mentor); Veldhuis, L.L.M. (mentor)","2015","Fluidic oscillators are devices that generate a temporally oscillating jet when supplied with a fluid under pressure. In recent investigations fluidic oscillators have proven to be very efficient in active flow control applications, while only little is known about the internal working mechanism of these devices. This thesis presents the internal flow structures and operating frequencies of multiple small-scale fluidic oscillator types for a range of subsonic inlet velocities. Time-resolved visualization of the flow structures inside the fluidic oscillators has been achieved by tracking the shadow of cornstarch particles suspended in the airflow. The application of this particle shadow velocimetry technique to the complex internal flow of fluidic oscillators has resulted in a detailed overview of the different internal flow fields, aided by two-dimensional numerical simulations. These simulations were performed for a wider range of flow rates, thereby extending the parameter range beyond what could be measured experimentally. Using the numerical results an empirical model is formulated, relating the flow rate and internal surface area of the presented fluidic oscillators to an oscillation frequency of the exit jet.","","en","master thesis","","","","","","","","2017-12-17","Aerospace Engineering","Aerodynamics & Wind Energy","","Aerodynamics","",""
"uuid:bae96d66-0e91-4298-b526-730397833f0e","http://resolver.tudelft.nl/uuid:bae96d66-0e91-4298-b526-730397833f0e","Increasing Acceptance of Tactile Feedback in UAV Teleoperations by Visualizing Force Fields","Ho, V.","Borst, C. (mentor)","2016","Due to the increasing complexity of controlling Unmanned Aerial Vehicles (UAVs), researchers have been trying to let automation take part of the UAV control in order to eliminate human error and reduce the workload of the operator. Such a system has been developed for UAV teleoperators which incorporates haptic feedback on the control stick based on a Collision Avoidance System (CAS). When nearing obstacles, the operator gets redirected by the haptic feedback and so avoiding a possible collision. However from previous and similar studies it was stated that haptic interfaces have a low user acceptance due to the limited knowledge and insight of the pilots on the automation. To improve the acceptance of the haptic feedback system this research adds additional visualizations to an existing interface. In order to evaluate these newly designed visuals, a human-in-the-loop experiment was performed. Results show that there were no significant differences between the different configurations, however, acceptance questionnaires filled in by the participants revealed that they preferred operating an UAV with additional visualizations. This means that raising the acceptance of the haptic interface was accomplished without deterioration of the operators safety, performance and workload.","Unmanned Aerial Vehicles (UAV); haptic interface; haptic feedback; tele-operations; collision avoidance; artificial force field; human-machine interaction; acceptance tactile feedback; haptic shared control","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","ATM, Airports and Safety","",""
"uuid:f3ab3dc4-a49d-4112-8f33-b382b6d4834c","http://resolver.tudelft.nl/uuid:f3ab3dc4-a49d-4112-8f33-b382b6d4834c","Jupiter's radiation belts at 13.8 GHz","Moeckel, C.M.","de Pater, I. (mentor)","2017","The Jupiter flyby of Cassini in 2001 allowed to study the gas giant in detail. Jupiter’s inner magnetosphere is populated by high energy particles, causing an intense radiation observable throughout the microwave regime. The re-calibration of the Cassini RADAR instrument has allowed for constraining the energy distribution of the electron population indicating a lack of high energy particles. Maps of the synchrotron radiation indicate a redistribution of the electrons compared to other epochs, confirming that the magnetosphere was in a highly disturbed stat. The retrieval accounted for the thermal emission from Jupiter and required depleting the polar regions of ammonia.","Jupiter; Synchrotron Radiation; Variability; Cassini","en","master thesis","","","","","","","","2017-11-22","Aerospace Engineering","Space Engineering","","","",""
"uuid:deb8cac6-ec8d-40eb-a154-a1dd3df55d0a","http://resolver.tudelft.nl/uuid:deb8cac6-ec8d-40eb-a154-a1dd3df55d0a","The Anti-Fairing: Reducing Drag in Junction Flows","Koers, A.J.","Belligoli, Z. (mentor); Dwight, R.P. (mentor); Eitelberg, G. (mentor); Veldhuis, L.L.M. (mentor)","2017","","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:66cddbd2-5f50-4fc7-be0b-468853128f37","http://resolver.tudelft.nl/uuid:66cddbd2-5f50-4fc7-be0b-468853128f37","Pumping Kites Wind Farm","Faggiani, P.","Schmehl, R. (mentor)","2015","","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:0cc79008-8a33-46c3-8949-e6124be16e73","http://resolver.tudelft.nl/uuid:0cc79008-8a33-46c3-8949-e6124be16e73","Welding of thermoplastic to thermoset composites through a thermoplastic interlayer","Van Moorleghem, R.","Fernandez-Villegas, I. (mentor)","2016","Research into the fusion bonding of joints containing thermoplastic and/or thermoset composites. A thermoplastic interlayer is co-cured with the thermoset that provides a fusible surface. Depending on the type of materials the interlayer can form an adhesive interface or a gradient interphase with the thermoset. Welding of thermoset composite to thermoplastic composite coupons with both interlayer types were performed. High lap shear strength are obtained, even after prolonged exposure to moisture. The joint that uses the gradient interphase has the potential to be certified for aerospace, in contrast with the adhesive interface type which faces the same challenges as seen in the certification of adhesive bonds. This technique provides an alternative to mechanical joining or adhesive bonding of cured thermoset structures.","welding; fusion bonding; interphase; interface; interlayer; co-cured layer; thermoset; joining; joints; composites","en","master thesis","","","","","","","","","Aerospace Engineering","ASM","","","",""
"uuid:382dec56-7789-40df-af28-f2e61de99fad","http://resolver.tudelft.nl/uuid:382dec56-7789-40df-af28-f2e61de99fad","Attitude control- and stabilisation moment generation of the DelFly using Wing Tension Modulation","Janssen, R.M.J.","Karasek, M. (mentor)","2016","","wing tension modulation; control; stabilisation; MAV; FWMAV; tail-less; DelFly","en","master thesis","","","","","","","","2018-10-26","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:aa5d1e6e-cba4-4906-978c-ca5f60d9a91a","http://resolver.tudelft.nl/uuid:aa5d1e6e-cba4-4906-978c-ca5f60d9a91a","Relative Navigation in Asteroid Missions: Dual Quaternion Approach","Razgus, B.","Mooij, E. (mentor); Choukroun, D. (mentor)","2016","","","en","master thesis","","","","","","","","2017-08-23","Aerospace Engineering","Space Engineering","","Astrodynamics & Space Missions","",""
"uuid:af0f0825-b3bd-41a3-94ca-336de550e337","http://resolver.tudelft.nl/uuid:af0f0825-b3bd-41a3-94ca-336de550e337","Increasing the Strength of an Adhesive Joint: Geometry Optimization of Complex Joint Configurations for Implementation in Composite Micro Truss Structures","van den Berg, L.J.","Bergsma, O.K. (mentor)","2016","A FEM-based tool was developed for optimization of the geometry of an adhesive joint for implementation in a composite micro truss structure. A genetic algorithm was employed to optimize the adhesive fillet and adherend local end geometry towards a uniform state of strain in the adhesive layer. It was found that the peak maximum principal strain in the adhesive has been reduced up to 36.8 %. However, it was concluded that the optimized joint configurations are unfeasible for implementation in composite micro truss structures as the joint efficiency was estimated to be below 1.0 %.","adhesive; joint; bonding; geometry optimization","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","Structural Integrity & Composite","",""
"uuid:b6626c3a-7fb6-4ab5-b150-45720bfdbf9c","http://resolver.tudelft.nl/uuid:b6626c3a-7fb6-4ab5-b150-45720bfdbf9c","Least-Squares Spectral Element Method for 2D Hyperbolic Systems of Equations","van der Bas, R.","Gerritsma, M.I. (mentor)","2007","The least-squares spectral element method (LSSEM) is a relatively new state of the art numerical method which is capable of solving complex problems with high accuracy. Very promising results for hyperbolic equations using a spacetime formulation have recently been obtained. In this report steady state solutions for 2D hyperbolic systems of equations are investigated. Especially, the solutions which contain discontinuities are a point of interest. The shallow water equations (SWE) and Euler equations are used for this purpose. By defining test cases for which the exact solutions are known the accuracy of the LSSEM is determined and more importantly it was observed that the shock position found by the LSSEM matched the analytical shock positions. However, this was only the case when conserved quantities were used. The use of primitive variables does not lead to correct shock positions. The results for the 2D channel flow with a circular bump are in agreement with known results for all (subsonic, transonic and supersonic) cases. However, applying and weighing the slip flow boundary condition is tricky and will influence the solution. Nonetheless, the LSSEM is capable of finding solutions for this type of problems which are in agreement with other numerical methods.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:03fbb394-6d1c-4adb-abe9-1c49301dbfa7","http://resolver.tudelft.nl/uuid:03fbb394-6d1c-4adb-abe9-1c49301dbfa7","Bio jet fuel from macro algae: A feasibility study into the end-to-end chain","Te Raa, H.R.","Ockels, W.J. (mentor); Melkert, J.A. (mentor); Beelaerts van Blokland, W.W.A. (mentor); De Groot, J.E.C. (mentor)","2010","Biofuels are essential for the future of aviation. The airline industry is a worldwide operating business to transport passengers and freight in an economical and fast manner. Jet engines consume kerosene to power the aircraft. However, kerosene is a distillate of crude oil and airlines are entirely dependent on this energy source. As a result, airlines are facing two problems. Firstly, the energy security is at stake when the conventional oil resources are depleted. Secondly, green house gases are produced by burning fossil fuels. Carbon dioxide is one of them and it is regarded by scientists as contributor to climate change (IPCC fourth assessment report group I, 2007). Biofuels solve these two issues, as they are renewable and they emit less carbon dioxide. Several airlines have already conducted test flights with biofuels, such as Virgin Atlantic, Air New Zeeland, Japan Air Lines and KLM. Feedstocks for these biofuels were camelina, jatropha and micro algae. Macro algae are also a feedstock for biofuels. This report is dedicated to the feasibility of bio jet fuel from macro algae from an end-to-end chain perspective. The main research fields were on the technical side, sustainability side and economical side of the bio jet fuel. Technically, it is possible to produce bio jet fuel from macro algae. Several macro algae cultivation methods and conversion methods exists to produce bio jet fuel. It is also better for the environment. The carbon dioxide emissions are reduced at least with 75% compare to fossil fuels. Besides this, the energy balance is also positive. More energy is produced in the form of biofuel than the energy is needed to produce it. An issue so far is the economical side of bio jet fuel. Bio jet fuel is substantially more expensive than fossil fuels. The price will decline when the production of macro algae increase. The transition from fossil fuels to biofuels will take decades and large investments are essential. In this report, several actions are discussed how the transition to bio jet fuels can be accelerated.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:56419c33-1656-491c-8e85-4351300c63e2","http://resolver.tudelft.nl/uuid:56419c33-1656-491c-8e85-4351300c63e2","Vortex velocimetry of air flows using Helium Filled Soap Bubbles (HFSB)","Yuvaraj, R.","Sciacchitano, A. (mentor)","2016","This thesis work illustrates the first of its kind solution to this problem of lack of seeding at vortex core in air flows, by the use of Helium Filled Soap Bubble (HFSB) which is a neutrally buoyant tracer particle in air flows. To analyse the lack of seeding in the vortex core, a 2D numerical simulation of particle motion in vortex flow is studied. This enables to understand the dependence of trajectory of the particle on its density and diameter, in vortex flows. Thus, the numerical simulation helps to explain the reason behind the empty core with the use of micro-size smoke particles and, the completely filled core by the homogeneous distribution of HFSB in the vortex core region. Flow visualisation experiment is performed on Leading Edge Vortex of a delta-wing at a chord based Reynolds number of 2*10^5 and 4*10^5 The flow visualization experiment revealed an empty core at the center of the vortex with the use of micro-sized smoke particle as tracer. On the other hand, the use of neutrally buoyant HFSB resulted in a homogeneous distribution of particles, especially in the core region of the vortex. The vector fields obtained from stereoscopic PIV measurements with the use of micro-sized smoke as tracer particle, displays the loss of information in vortex ow particularly in axial velocity and axial vorticity fields. In contrast, the use of HFSB as tracer particle, resulted in particle filled vortex core and displays vector fields that are consistent with literature. The use of HFSB as tracer particle enabled to perform tomographic Particle Tracking Velocimetry (PTV) (3C-3D) on the Leading Edge Vortex. Tomo PTV performed on the vortex ow field enabled to obtain the velocity and vorticity fields in all three directions.","Particle Image Velocimetry; PIV; Helium Filled Soap Bubbles; HFSB; Vortex velocimetry; Delta wing; Neutrally buoyant particle","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:fef26f7d-eab7-42dc-a7f7-63e21f5e284b","http://resolver.tudelft.nl/uuid:fef26f7d-eab7-42dc-a7f7-63e21f5e284b","Natural gas displacement by wind curtailment utilization in combined-cycle power plants","Van den Oudenalder, F.S.C.","Gangoli Rao, A. (mentor)","2016","","natural gas preheating; combined-cycle; curtailment utilization; curtailment modelling; thermal energy storage; latent heat storage","en","master thesis","","","","","","","","","Aerospace Engineering","Flight performance and Propulsion","","","",""
"uuid:379da7cb-abf9-4f5d-84bd-2957fb7aafd5","http://resolver.tudelft.nl/uuid:379da7cb-abf9-4f5d-84bd-2957fb7aafd5","Energy dissipation response of a rectangular metal tube on axial impact","Wolken, M.","Van Campen, J.M.J.F. (mentor); Gransden, D.I. (mentor)","2017","A surrogate model is used to predict the energy dissipation response for a rectangular beam, initiated by an axial impact. This method is used for one type of steel, after which a generalization is performed to make it available for multiple types of metal.","Impact; surrogate model; energy dissipation","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:6ac10891-98d9-4173-9f34-533149664ec0","http://resolver.tudelft.nl/uuid:6ac10891-98d9-4173-9f34-533149664ec0","Measuring Surface Deformation Caused by Permafrost Thawing Using Radar Interferometry, Case Study: Zackenberg, NE Greenland","Yuan, Y.","Hooper, A.J. (mentor); Hanssen, R.F. (mentor)","2011","Permafrost in high-arctic regions has been very much influenced by global warming. Many thousands of square kilometers of permafrost are under certain degree of thawing. Site measurements have provided useful data for researchers. However, these ground-based measurements are usually site-specific with poor spatial coverage. Here we apply Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) to measure the surface deformation over permafrost north-east Greenland during the past two periods 1995--1999 and 2006--2009 to infer permafrost behaviors. We have found a considerable rate of surface subsidence occurring with respect to a relatively stable area. Over the whole study area, during 1995--1999, we find a surface subsidence rate of 0.3--2.4 mm/yr and a seasonally varying displacement of 0.4--6.1 mm with subsidence occurring during the thawing season of each year. While in period of 2006--2009, we find the overall surface subsidence rate goes up to 0.8--2.7 mm/yr and the seasonally varying displacements increased to 2.3--7.4 mm within the thawing season. Comparing with the two periods, we find a general accelerating trend in subsidence rate of 4.5 x 102 mm/yr2, which indicates a acceleration in permafrost thawing rate. We also find a general increment in surface seasonal varying displacements of 1.9 mm, which indicates a thickening trend in the active layer. In total, by applying MT-InSAR technique over the 5000 km2 study area, we have found a permafrost area 506.1 km2 of that is under thawing and the general magnitude of permafrost thawing rate is 17.0±8.4 cm/yr during 1995--1999. During 2006--2009, we have found 633.9 km2 of permafrost area is thawing with a magnitude of thawing rate about 24.0±12.0cm/yr. We have also estimated the total volume loss of permafrost as (2.1±1.1) x 108 m2 and (3.0±1.5) x 108 m3 in each corresponding period. Further, assuming the linear relationship between the thawed permafrost and the released methane fluxes observed during 19-Jun-1997 to 18-Aug-1997 at Zackenberg valley, we apply this relationship to the whole subsidence area. We estimate the total magnitude of methane fluxes released from the study area within this period, which is about 1081.7±398.5 T.","permafrost; InSAR; Deformation; Thawing; Methane","en","master thesis","","","","","","","","","Aerospace Engineering","Mathematical Geodesy and Positioning","","Geomatics","",""
"uuid:ea1f5af4-508e-4490-b4b7-f0fbaf181983","http://resolver.tudelft.nl/uuid:ea1f5af4-508e-4490-b4b7-f0fbaf181983","What is the ideal powercurve?: Optimizing the powercurve above rated wind speed for large offshore wind turbines","Barten, O.","van Bussel, G.J.W. (mentor); Zaaijer, M.B. (mentor); Diepeveen, N. (mentor)","2012","Current large offshore wind turbine design practice is using a powercurve that is flat above rated wind speed. The most important reason for this is generator and electric system costs, while another reason is that parts such as blades and tower are not designed for higher loads. In this report, it is investigated which other possibilities are present than a flat powercurve. These possibilities include a maximum thrust-designed, maximum torquedesigned, and fatigue damage-designed powercurve. Furthermore, the NREL 5 MW powercurve is optimized using part-wise engineering-based cost functions. For this turbine, 5% of the levelized cost of energy is saved if the powercurve is adjusted. The main proposed changes are peak shaving, a rotor speed increase and a power decrease at high wind speeds.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","Sustainable Energy Technology","",""
"uuid:d4e2e5d7-0a68-45d9-9360-33f1861c7956","http://resolver.tudelft.nl/uuid:d4e2e5d7-0a68-45d9-9360-33f1861c7956","Silicate cloud formation in the atmospheres of close-in super-Earths and gas giants","Mahapatra, G.","Stam, D.M. (mentor)","2016","Context: Clouds form in the atmospheres of brown dwarfs and extrasolar planets. Recent observations of planets orbiting extremely close (<0.1 AU) to their stars indicate possible atmospheres with silicate compositions resulting due to vaporization of silicate magma from their surface. Such atmospheres are heavily dependent on compositions of the planetary crust which in turn might influence the kind of dust particles that form in such atmospheres. Aims: We identify five types of silicate compositions commonly found on Earth and derive atmospheric chemistry with Earth silicates as starting compositions using an equilibrium chemistry atmospheric model. Following the mineral cloud modelling approach for hot atmospheres of brown dwarfs and giant gas planets, we model the dust cloud formations resulting due to varying Earth silicate compositions and apply that to investigate the possibility of clouds on sample atmospheres of a giant gas planet, 55 Cnc e, HD149 026b and CoRoT-7b. Methods: Atmospheric compositions for the planets have been derived using a previously validated Equilibrium chemistry code. We derive our atmospheric chemistry using element abundances from previously studied Earth surface compositions which is provided as an input to the 1D kinetic cloud formation model, DRIFT. We perform cloud modelling on each of the atmospheres with varying silicate compositions and study the resulting cloud properties such as particle growth, particle sizes and their composition at various stages. Results: We present the cloud structures resulting due to varying Earth silicate compositions on four different types of planets. The clouds show variations in the dust properties due to different starting compositions with differing average particle sizes but the formation conditions such as average particle size, cloud thickness and condensation altitude largely remain dependent on the local gas density and temperature. The cloud layers on 55 Cnc e, HD149 026b are found to be greatly varying in terms of their geometrical thickness, particle sizes and number densities and are primarily composed of silicates of elements such as Mg, Si, Fe and Al.","","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:e134587d-da8c-4f47-b4a6-bcec254a1ef5","http://resolver.tudelft.nl/uuid:e134587d-da8c-4f47-b4a6-bcec254a1ef5","Transient modelling and analysis of the OP16 gas turbine in GSP","Singh, V.","Axelsson, L. (mentor); Visser, W.P.J. (mentor)","2015","With the current trend towards flexible engine operation with high efficiency and low emissions, dynamic modelling of gas turbines has become critical to ensure safe and acceptable engine performance. Dynamic models are essential for design and development of control systems and for analysis of transient manoeuvres that are impractical to test. This M.Sc. thesis project is carried out in collaboration with OPRA Turbines B.V. The aim of the project is to develop a dynamic model of the OP16 gas turbine. OP16 is a single-shaft all-radial industrial gas turbine rated at 1.9 MW, manufactured by OPRA Turbines. The resulting model can be used to simulate and analyse transient performance of the OP16 engine during manoeuvres of interest to OPRA Turbines. The model can also be used for designing initial fuel control strategies. The Dutch National Aerospace Laboratory’s Gas turbine Simulation Program (GSP) is used as the modelling platform. GSP is a 0-D, component based modelling environment that allows for steady-state and transient performance simulation of any gas turbine configuration. Since transient simulation in GSP is follows the quasi-steady-state approach, the steady-state model of OP16 is first developed. In order to evaluate the influence of steady-state heat loss on engine performance, thermal network modelling is also included. The steady-state model is verified against measured data across the entire operational envelope of OP16. The model is found to accurately simulate the steady-state performance of OP16 near the full load operating point. The steady-state model is extended to simulate transient performance of OP16 by implementing engine-specific details. The transient model is verified by comparing model simulations to the measured data for a load step near the full-load operating point. The transient effects including rotor inertia, heat soakage and volume dynamics are analysed to determine their influence and importance for the transient behavior. Rotor inertia is found to dominate the transient behaviour of OP16 while heat soakage effects and volume dynamics remain negligible in comparison. The transient model of OP16 is used to simulate engine behaviour when performing load sheds. The influence of fuel heating value, fuel valve closing time and combustor volume is analysed. One important aspect to guarantee safe operation is to be able to shut-off the fuel supply as soon as possible in case of an engine trip. From the simulations it is found that lower LHV fuels tend to result in higher rotor over-speeds in case of a load shed. For a LHV as low as 5.8 MJ/kg, the fuel valve closing time during a load shed should not exceed 0.7 seconds in order to maintain the rotor over-speed within acceptable limits, whereas for natural gas type of fuels the fuel valve closing can be up to 0.9 seconds.","gas turbine; transient performance analysis; GSP","en","master thesis","","","","","","","","2019-12-16","Aerospace Engineering","Flight performance and Propulsion","","","",""
"uuid:f18687c0-adf2-43dc-8485-ee90716c1d5d","http://resolver.tudelft.nl/uuid:f18687c0-adf2-43dc-8485-ee90716c1d5d","A CFD Investigation into Ground Effect Aerodynamics","Genua, E.","Gerritsma, M. (mentor)","2009","A computational study of the ow around an inverted 2D airfoil in ground effect is performed. The effect of mesh parameters and turbulence model on the solution is thoroughly investigated. Results are compared to previous works found in literature and an improvement in CFD predictive capabilities is noticeable. Spalart-Allmaras shows to be the most accurate and robust turbulence model among the ones tested. An optimal range of mesh characteristics is identified. Within this range the main features of the ow, including separation due to adverse pressure gradient and subsequent downforce reduction, are correctly captured.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9c1ec4e8-bcc3-45e9-93d7-26293db08d2f","http://resolver.tudelft.nl/uuid:9c1ec4e8-bcc3-45e9-93d7-26293db08d2f","Integrated Water Vapour mapping using vertical Wind Profiles","Jongkind, E.","Lindenbergh, R.C. (mentor); Van der Marel, H. (mentor)","2011","Water vapour in the atmosphere is a key variable in the prediction of heavy rain and thunderstorms. Water vapour in the atmosphere is still badly modeled although more and more ground based, airborne, as well as spaceborne measurements are retrieved. The main input for current water vapour maps are Integrated Water Vapour (IWV) measurements obtained every 15 minutes from GPS ground stations. My graduation project focuses on the question whether the combination of water vapour measurements and wind measurements can increase the quality of these water vapour maps. The increase in quality is expected as wind is moving the water vapour, also called advecting. Therefore in addition, 3D wind data obtained from HIRLAM is incorporated in the map making. HIRLAM is the abbreviation for High Resolution Limited Area Model for Numerical Weather Prediction, and this model is created by a European consortium of meteorological institutes. A modified Kriging interpolation approach is used to combine both current measurements and measurements from the past advected by the wind. By using a case study it is investigated whether the IWV prediction in between the GPS ground stations could be improved. For this case study, and using this method, we can conclude that on average the IWV maps are not improved by incorporating advected measurements. However, there are also locations for which the IWV predictions are improved.","water vapour; kriging; radiosonde; GPS; meteorology; wind","en","master thesis","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:f04b7f3e-7df6-4132-9037-50b48b431523","http://resolver.tudelft.nl/uuid:f04b7f3e-7df6-4132-9037-50b48b431523","Implementation of a new transition prediction method in xfoil: Predicting transition in suction boundary layers","Bongers, J.","Bakker, P.G. (mentor)","2006","To reduce drag on wings, aerodynamicists have long been trying to keep the boundary layer on the wings laminar and to postpone transition to a turbulent boundary layer. To achieve this laminar _ow control by means of boundary layer suction can be used. At the Delft University of Technology xfoil has been adapted to design airfoils using boundary layer suction. This version is called xfoilsuc. The use of this design program was restricted because the transition point prediction methods in xfoilsuc could not predict the damping of disturbances in the boundary layer when suction was used. The objective of this study was therefore to implement a reliable transition prediction method into xfoilsuc that could predict transition for boundary layers with and without suction. To achieve this a new database eN method was implemented into xfoilsuc. This new method, dubbed the Improved eN-method, was developed by Van Ingen with some assistance from the present author. It uses the solutions of the Orr-Sommerfeld equation as calculated by Arnal, that describe the stability diagrams for _fteen values of Re_crit . These _fteen values of Re_crit represent boundary layers with shapefactors between 2.216 and 35.944. As characteristic parameter, the boundary layer shapefactor is used to correlate arbitrary boundary layers to a Re_crit value. By scaling and shifting some parameters, the data is stored in splines suitable for interpolation and some extrapolations. It was found that when using the Improved eN-method in xfoil due to the interaction between the boundary layer iterations and the transition prediction, most solutions would not converge. A method using forced transition was developed to remedy this problem. Using this method, convergence of the boundary layer solution is achieved without a_ecting the accuracy. The Improved eN-method was found to be able to accurately predict transition in boundary layers with and without suction. After the implementation of the Improved eN method a study into the quality of xfoils laminar boundary layer calculations revealed that the shapefactor can sometimes be a bit o_, compared to a _nite di_erence method using the pressure distribution as calculated in xfoil. This has an impact on the predicted transition point. Another problem is that for high suction velocities the shapefactor can go below the value of 2, which is considered erroneous. Further research into this is recommended. A case study concerning the DU99 airfoil, originally designed for the standard class ASW-28 sailplane, was done using the Improved eN-method. For this airfoil a suction distribution is designed that results in a 50 to 75 % reduction in drag in the low drag bucket, excluding the suction drag. Also the Clmax value is increased from 1.4 to 1.7. This airfoil is therefore well suited for further testing in a windtunnel.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:78593d20-738f-4e3f-a481-707fcc331810","http://resolver.tudelft.nl/uuid:78593d20-738f-4e3f-a481-707fcc331810","A quantitative comparison study of a contextual and cognitive model of Air Traffic Controller workload","Steiner, J.M.","Sharpans'kykh, O.A. (mentor); Borst, C. (mentor)","2015","Up to this point, research into Air Traffic Controller workload has primarily focused on a number of discrete areas. However, it is widely recognized that different components from these respective fields all contribute to the workload an Air Traffic Controller experiences. Hence, this study has tried to bridge this gap by quantitatively comparing two previously developed models of Air Traffic Controller workload. For the comparison, the contextual Dynamic Density (DD) and the cognitive Man-machine Integration Design and Analysis System (MIDAS) have been chosen. This is due to the well-established nature of these models in their respective fields. In the comparison context of three Conflict Detection & Resolution scenarios, two consistent quantitative relations have been found between a number of DD and MIDAS variables respectively. The most consistent relation effectively illustrated the quantitative relation between the inter-aircraft distance based DD complexity and the MIDAS cognitive/average channel load. Given this relation, a much more thorough understanding has been obtained of how the workload quantification types proposed by both models relate to one-another. It was concluded that none of the models could effectively model the expected workload behavior in solitude. Therefore, it was proposed that knowledge from these models should be combined. Three of such model integration proposals have been given. The proposal in which the MIDAS channel loads were convoluted with the locally applicable DD complexity values appeared to illustrate the physically desired workload behavior.","air traffic control; workload; contextual workload modelling; cognitive workload modelling; quantitative model comparison; MIDAS; dynamic density","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Air Traffic Management, Airports and Safety","",""
"uuid:7730dd69-2bb8-4047-8f6d-5681cfd04cee","http://resolver.tudelft.nl/uuid:7730dd69-2bb8-4047-8f6d-5681cfd04cee","Physical Splines for Aerodynamic Modelling of Innovative Control Effectors","van der Peijl, I.V.","de Visser, C.C. (mentor)","2017","Multivariate simplex B-splines as a modelling technique provide more accurate models than standard polynomial models, which makes them an excellent modelling tool. Their coefficients, which are expressed in a barycentric coordinate system, are abstract. In this paper a physical transformation matrix is derived which can be applied to transform B-coefficients into physical coefficients. The result is a set of per-simplex polynomials in Cartesian space. Direct computation of physical coefficients is also possible, but undesired because the physical transformation matrix is ill-conditioned and causes inaccurate regression. A case is made for using Kuhn’s triangulation algorithm which is preferred for perfectly gridded data structures, instead of the more conventional Delaunay method for triangulation of the model domain. The physical spline modelling technique is applied on Lockheed Martin’s Innovative Control Effector concept aircraft. Two models are created: a large set of simplices hosting polynomials of degree one, and a smaller set of simplices with higher order polynomials. These both are analytical formulations which can be used for control allocation. The resulting models are accurate and C0 continuous, but have local areas of error which could have an undesirable effect on control allocation. The high degree model more is affected by this more than the degree one model.","Multivariate Simplex B-Splines; Physical Splines; Innovative Control Effectors; ICE; Kuhn; Triangulation; Modelling","en","master thesis","","","","","","","","2020-04-07","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:ce266e05-cf6a-4661-bde4-e50860ea0db5","http://resolver.tudelft.nl/uuid:ce266e05-cf6a-4661-bde4-e50860ea0db5","Increased Energy Yield using the Smart Rotor: Sizing and Control of Trailing Edge Flaps on a Smart Rotor for Maximum Power Generation in Low Fatigue Wind Regimes","Smit, J.","van Bussel, G.J.W. (mentor); van Kuik, G.A.M. (mentor); van Wingerden, J.W. (mentor); Bernhammer, L. (mentor)","2013","","Windenergy; wind turbine; smart rotor; performance optimization; trailing edge flap; smart rotor control; fatigue","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","","",""
"uuid:d10ee0cc-eef4-4809-8a72-152d313678e0","http://resolver.tudelft.nl/uuid:d10ee0cc-eef4-4809-8a72-152d313678e0","Investigation of Factors that Influence Wind-Tunnel Modeling in Vehicle Thermal Simulation","Kumar, A.","Hickel, S. (mentor)","2016","Detailed investigation of factors that influence Wind-Tunnel modeling in vehicle thermal simulation. Tasks involved observing and investigating the additional equipment attached to the wind tunnel model that could alter the results when compared with the computational simulation results. All the study is based on computational simulation finally comparing with experimental results","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Aerodynamics","",""
"uuid:a77149c9-4fd0-4cdc-ade9-6c5aca719a64","http://resolver.tudelft.nl/uuid:a77149c9-4fd0-4cdc-ade9-6c5aca719a64","Thermal modelling and design of the DelFFi satellites","Van Boxtel, T.","Guo, J. (mentor)","2015","The DelFFi mission’s satellites employ a variety of subsystems, whose temperature ranges need be controlled. Thermal design for DelFFi is challenging because of its body mounted solar cells and high heat dissipation internal components, such as the thruster and inter-satellite link device. The goal of this thesis was summarized in the research question: Is it possible, and if so how, for the DelFFi satellites' temperatures to be controlled by passive means? The answer to this question was found through thermal modelling, testing and thermal control system designs. A detailed thermal model was created in ESATAN-TMS software. To verify critical model parameters, a set of 7 component level tests was performed. PC/104 conduction and mid-plane stand-off conduction in particular proved to be critical model data, with a significant deviation from their calculated theoretical values. With use of the model, three different thermal control system designs were made. All designs employ very low conductivity spacers and stand-off's, to reduce coupling with the cold structure. Also, a combination of aluminium, Kapton and tarnished copper thermal tapes are used. Concluded was that the batteries and the thruster unit were the thermally critical subsystems. The battery temperature range cannot be made small enough by passive means only, so it is advised to employ a heater for safety. The thruster unit propellant should be allowed to freeze, or its freezing point should be reduced by the use of ammonia or alcohol. With these adaptations to the thruster and battery, the thermal requirements of the satellites are met. This confirms that with these measures a working thermal control system can be implemented on the DelFFi satellites.","thermal modelling; thermal design; satellite thermal control; DelFFi; Delfi space","en","master thesis","","","","","","","","2015-02-16","Aerospace Engineering","Space Flight","","Space Systems Engineering","","52.01, 4.22"
"uuid:d65baa7b-e478-4352-a50a-3013e4802739","http://resolver.tudelft.nl/uuid:d65baa7b-e478-4352-a50a-3013e4802739","Validating a Human Controller Model for Preview Tracking Tasks: Identification of the Effects of Spatial Occlusion using Eye-Tracking","Rezunenko, E.M.","Pool, D.M. (mentor); van der El, K. (mentor); Mulder, M. (mentor)","2016","This paper presents an experimental validation of a recently developed two-point human controller (HC) model for preview tracking tasks. During a human-in-the-loop experiment, subjects tracked identical target signals with zero preview, 1.5 seconds of preview, and two occlusion conditions, blocking either the 0-0.5 s, or 0.35-0.85 s region from the HC’s view. Subjects’ gaze positions were recorded with a fixed-base eye-tracker. Measurements of the HC behavior were analyzed in the frequency domain by estimating the parameters of a quasi-linear model and compared to the distributions and means of the gaze data. The model fits accurately to the measurement data, therefore its validity is extended to occlusion scenarios. We suggest that internal processing of the target signal is performed by HCs, allowing them to respond to the signal inside the occlusion region by interpolating the last available position of the target preview. Results show a correlation between foveal gaze position and identified near-viewpoint locations, while the far-viewpoint is perceived peripherally by the HC. We consider the model viewpoints to be physically representative of the visual regions used by HC for gathering preview information.","preview control; manual control; system identification; parameter estimation; occlusion; eye-tracking","en","master thesis","","","","","","","","2021-10-31","Aerospace Engineering","Control and Operations","","Control and Simulation","",""
"uuid:43525b03-f784-4db8-85c8-0d68918f1ac6","http://resolver.tudelft.nl/uuid:43525b03-f784-4db8-85c8-0d68918f1ac6","Going against the flow: An experimental investigation into the flow mechanics of dimpled surfaces in turbulent boundary layers","van Campenhout, O.W.G.","Veldhuis, L.L.M. (mentor); van Oudheusden, B.W. (mentor); Schrijer, F.F.J. (mentor)","2016","Any reduction in vehicle drag or fluid resistance provides a potential of substantial energy savings, with obvious benefits to the economy, environment and overall industrial competitiveness. Although various experimental studies have confirmed the potential drag reduction of dimpled surfaces in a turbulent boundary layer (BL), the working mechanism behind the effect remains largely unresolved. An experimental investigation is performed with the objective to strengthen the understanding of this novel aerodynamic surface and its interaction with the turbulent BL. Direct force measurements are combined with Particle Image Velocimetry (PIV) and Particle Image Surface Flow Visualization (PISFV). The direct force measurements reveal that the drag reduction is highly sensitive on flow conditions, a finding with significant implications for further research as well as for potential applications. Furthermore, the PIV and PISFV measurements reveal a spanwise oscillation at the surface and at 0.2δ due to the interaction of individual dimple flow topologies, which are of the converger-diffuser type. The measurement of this oscillation is the first of its kind and provides strong evidence of a state-of-the-art drag reduction theory: the interaction between dimples causes alternating spanwise excitations of the near-wall flow which interacts with the turbulent coherent structures and therefore leads to a reduction of the turbulent drag. This theory is in contrast to what has often been proposed in literature. Dimples potentially have significant advantages over other means of passive flow control for drag reduction: they are very shallow and therefore do not require complicated cleaning or maintenance procedures, also they are not prone to wear such as riblets. Furthermore, they can easily be (retro)fitted on skin panels. This research provides fundamental data that contributes to the understanding of the flow mechanics of these dimpled surfaces in turbulent BLs.","passive flow control; drag reduction; PIV; turbulent boundary layers","en","master thesis","","","","","","","","2018-08-12","Aerospace Engineering","Aerodynamics","","","",""
"uuid:5bfe26e3-f3cd-4445-afe9-159e6b8beff3","http://resolver.tudelft.nl/uuid:5bfe26e3-f3cd-4445-afe9-159e6b8beff3","Constraints from ice dynamics for ice load histories from GIA data of the last ice age, and evidence from GIA data for glaciation of the North Sea Basin","Van den Broek, M.","Vermeersen, L.L.A. (mentor); Schotman, H.H.A (mentor)","2006","","glacial isostatic adjustment; ice dynamics; north sea basin","en","master thesis","TU Delft, Aerospace Engineering, Astrodynamics and Satellite Systems","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8f73b31c-4306-4b44-9937-3b4d23a4a53f","http://resolver.tudelft.nl/uuid:8f73b31c-4306-4b44-9937-3b4d23a4a53f","A Deployable Telescope for Sub-Meter Resolutions from MicroSatellite Platforms","Dolkens, D.","Kuiper, J.M. (mentor)","2015","Sub-meter resolution satellite imagery serves a more and more important role in applications ranging from environmental protection, disaster response and precision farming to defence and security. Earth Observation at these resolutions has long been the realm of large and heavy telescopes. The costs of building and launching such systems are enormous, which results in high image costs, limited availability and long revisit times. Using synthetic aperture technology, instruments can now be developed that can reach these resolutions using a substantially smaller launch volume and mass. In this thesis, a conceptual design is presented of a deployable synthetic aperture instrument. The instrument can reach a ground resolution of 25 cm from an orbital altitude of 500 km. In terms of resolution, the system is compliant with current state-of-the-art systems, such GeoEye-2 and Worldview-3. With an estimated mass of 75 kg, the system is significantly lighter than conventional solutions. The thesis covers the optical and mechanical design of the instrument as well as the calibration strategy and required image processing techniques. The optical design of the deployable telescope is based on a Korsch Three Mirror Anastigmat. The entrance pupil of the instrument consists of three rectangular mirror segments that, when deployed, span a pupil diameter of 1.5 meters. To ensure that the telescope can deliver a deliver a diffraction limited performance while operating in a harsh and dynamic space environment, the telescope features a robust thermo-mechanical design, aimed at reducing mechanical uncertainties to a minimum. In addition, the system will feature an in-orbit calibration system. Following the launch, actuators beneath the primary mirror segments will correct the position of the mirror segments to meet the required operating accuracies. During operations, a passive phase diversity system will be used. This system can retrieve residual wavefront errors and use that knowledge to restore the image with a Wiener deconvolution filter. Using this approach, an almost diffraction limited image quality can be achieved in all operating conditions.","Synthetic Aperture; Deployable Telescope; High Resolution; Earth Observation; Optics; Opto-mechanical Design; Image Processing","en","master thesis","","","","","","","","","Aerospace Engineering","Space Systems Engineering","","","",""
"uuid:a56090a3-bbce-404b-8e4b-d0e9050b518a","http://resolver.tudelft.nl/uuid:a56090a3-bbce-404b-8e4b-d0e9050b518a","Robust Nonlinear Spacecraft Attitude Control: An Incremental Backstepping Approach","Acquatella, B.P.J.","Chu, Q.P. (mentor); Falkena, W. (mentor); Van Kampen, E. (mentor)","2011","In order to meet requirements in terms of robustness, stability, and performance for future generations of advanced attitude control systems, a sensor-based approach using Incremental Backstepping control is developed and proposed in this thesis. Assuming full state availability and fast control action, the resulting time-scale separation between the state of the system and the state of the controller allows to consider an incremental form of the attitude dynamics, where backstepping controllers can be designed to achieve stability and convergence with incremental inputs. This results in integral-control action where information of angular acceleration and actuator output measurements is required. The robustness and the full potential of Incremental Backstepping are evidenced in face of external disturbances, uncertainties, and unknown parameters. External disturbances are well suppressed in contrast with conventional backstepping and Lyapunov-based (non)linear controllers. Furthermore, the attitude stabilization results to be insensitive to parametric uncertainties and robust against model uncertainties. However, this comes at the expense of higher control effort. Moreover, with the influence of model and parametric uncertainties the resulting closed-loop dynamic performance can be better accounted for by studying the convergence and stability properties in terms of Lyapunov theory. This methodology results in a simple, yet effective, family of robust nonlinear attitude controllers which aims to meet demanding requirements in terms of robustness, stability and performance, which in turn, close the gap towards the development of future advanced attitude control systems.","Spacecraft Attitude Control; Nonlinear Control; Backstepping; Incremental Backstepping; Incremental Nonlinear Dynamic Inversion; Lyapunov-based control; Modified Rodrigues Parameters","en","master thesis","","","","","","","","2016-06-01","Aerospace Engineering","Control and Operations (C&O) - Control and Simulation Division (C&S)","","Dynamics and Control of Aerospace Vehicles","",""
"uuid:4c7eb631-977b-4848-b21d-8e15c39623d6","http://resolver.tudelft.nl/uuid:4c7eb631-977b-4848-b21d-8e15c39623d6","Development and testing of nano-porous micro-carriers for corrosion inhibitor release from protective organic coatings","Denissen, P.J.","Garcia Espallargas, S.J. (mentor); Van der Zwaag, S. (mentor)","2015","","","en","master thesis","","","","","","","","2017-12-09","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","Novel Aerospace Materials","",""
"uuid:9ecec1a5-e3fa-4468-9ac0-e6ffacaa1905","http://resolver.tudelft.nl/uuid:9ecec1a5-e3fa-4468-9ac0-e6ffacaa1905","Estimation and reduction of peak-locking errors in PIV measurements","Kislaya, A.","Sciacchitano, A. (mentor)","2016","In PIV, the systematic tendency of the measured sub-pixel displacement to be biased towards the integral pixel values is called peak-locking. This occurs when the particle image diameter is less than a pixel. The bias error causes inaccuracy in the measured PIV data which does not reduces with increase in the sample size. Recently developed LaVision’s optical diffuser was investigated to determine the reduction in peak-locking. The point-spread-function width of diffuser was examined to calculate the change in the shape and size of the point source under the influence of different parameters. Planar-PIV experiment were carried out in uniform, low-speed and high-speed flow conditions to analyse the effectiveness of the optical diffuser in reducing the bias error and change in the random error. Also, a comparative assessment was done between the use of conventional defocusing and optical diffusers during image acquisition. The use of optical diffusers reduces the bias error and random error by a factor of three. The reduction in the measurement error is similar to the best defocused optical position of the lens which is very difficult to determine. Additionally, an experimental analysis was done with three different camera-lens combination to determine the best relative aperture size for keeping the measurement error minimal for the large scale 2D PIV. With the help of optical diffusers, experimentalists can have more accurate PIV measurements which would lead to more realistic capturing of the flow phenomenon. With the use of optical diffusers, it would also help the CFD and theoretical experts to compare their predictions with better experimental benchmark results.","PIV; particle image Velocimetry; peak-locking errors; bias errors; random errors; LaVision Optical diffusers; Large scale PIV; Planar PIV","en","master thesis","","","","","","","","2017-08-26","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:50ca18c8-15aa-4b73-aa7a-f1d3453dd562","http://resolver.tudelft.nl/uuid:50ca18c8-15aa-4b73-aa7a-f1d3453dd562","The least-squares method with blended hierarchical basis functions: An implementation in Haskell with applications in uid dynamics","Vrijkorte, H.J.","Bijl, H. (mentor); Gerritsma, M.I. (mentor); Ryan, J.K. (mentor); Dwight, R.P. (mentor); Kreeft, J.J. (mentor); Palha da Silva Clerigo, A. (mentor)","2010","This research is aimed at the development of the novel least-squares method with blended hierarchical basis functions (ls-bhbf method), combining blended hierarchical basis functions (bhbf's) with the proven least-squares spectral element method. The ls-bhbf method is not based on standard elements and is therefore ideally suited to model general, curvilinear geometry in any number of dimensions. A global assembly procedure is not needed because bhbf's are inherently continuous across elements. Moreover, bhbf's allow non-uniform p- re_nement without functional incompatibilities. This report describes in detail the theoretical foundations and practical aspects of the ls-bhbf method. As part of the work, an implementation of the ls-bhbf method has been developed in the functional programming language Haskell. The implementation is used to assess the practicality and performance of the method. The program is validated using the benchmark case of laminar ow around a circular cylinder in a narrow channel and the two-dimensional lid-driven cavity ow. The ls-bhbf method was found to be exible and general, and performs satisfactorily for the two incompressible ow problems. However, the method proved relatively cumbersome to implement and the computational performance of the implementation was not impressive. There is still a lot of potential for further research and development. The applicability of the ls-bhbf method is decidedly greater than what could be explored in this work.","least-squares finite element method; spectral elements; blended basis functions; hierarchical topology; Navier-Stokes; lid-driven cavity; circular cylinder; functional programming; Haskell","en","master thesis","","","","","","","","","Aerospace Engineering","","","Aerospace Engineering","",""
"uuid:6762136d-5f8c-46a8-9ee5-18347c43fc0e","http://resolver.tudelft.nl/uuid:6762136d-5f8c-46a8-9ee5-18347c43fc0e","Preliminary multi-mission UAS design","Veerman, H.C.M.","Stoop, J. (mentor); Poppinga, G. (mentor); Hoogendoorn, S. (mentor)","2012","Unmanned vehicles are important when it comes to performing a desired task in a dangerous or inaccessible environment. Unmanned robots, have been successfully used for many years. More recently, a growing interest in Unmanned Aircraft Systems (UASs) has arisen. In the past few years the development of sensors, microprocessors and propulsion systems resulted in UASs that are smaller, lighter and more capable than ever before. This leads to endurance, efficiency and autonomy levels that exceed the capabilities of manned flight. A large number of successful designs have been created by several universities, commercial companies and research agencies. Due to the wide variety of applications, several configurational concepts have been developed. As a result, most UAS designs are optimized for a dedicated task. In order to perform different tasks, users need to have access to multiple UASs. This means that manufacturers and users have to maintain production and support lines for multiple UASs. The goal of this thesis was to create a preliminary design of a multi-mission UAS by using off-the-shelf systems. This UAS must be able to perform both low and high speed missions. To reach the stated goal a clear overview of all requirements had to be created first. This was followed by extensive market research in order to get an overview of the performance of current UAS designs. This market research was captured in a database. Based on the requirements in combination with the obtained database, all UAS classes and configurational options have been evaluated. The evaluation revealed that a new fixed wing electrical powered mini UAS design may be able to comply with the all UAS requirements. Based on the UAS database, weight estimation relationships for preliminary mini UAS design were derived. These relationships were used for the preliminary UAS performance and weight estimation. After investigating the technical and operational feasibility, the compliance with respect to the requirements was checked. This resulted in a new UAS design point. Subsequently, the UAS design was analyzed in more detail. Optimization of the wing was performed by using a quasi-3D optimizer. This was followed by a tail design that was based on UAS reference data and volume coefficients. The resulting wing and tail design were evaluated by investigating the wing-tail effects and the primary static \& dynamic stability derivatives. This was followed by an evaluation of the material options for the structure. During this evaluation a new manufacturing technique, 3D printing, was tested. Subsequently, the propulsion system design was performed by using a UAV Propulsion Development Kit (UPDK). This UPDK is able to estimate the performance of multiple engine-propeller combinations. Based on the evaluation of the top five combinations, a combination was selected. Finally, the additional UAS subsystems were selected. After the preliminary UAS design was completed, the effectiveness of the design was evaluated. Together with off-the-shelf systems it was possible to create a design that is able to comply with most requirements. The WER for the payload weight was found to be inaccurate. This was caused by the fact that current UASs are equipped with heavier or additional payloads. The WER for the empty weight slightly underestimated the structural weight of the UAS. Overall can be concluded that it is possible to create a preliminary mini UAS design capable of performing both low and high speed missions using off-the-shelf systems.","UAS; UAV; preliminary UAS design; preliminary UAV design","en","master thesis","","","","","","","","2012-09-08","Aerospace Engineering","Design, Integration & Operations of Aircraft and Rotorcraft","","","",""
"uuid:60ad4fc1-73eb-4d7d-b598-771660342449","http://resolver.tudelft.nl/uuid:60ad4fc1-73eb-4d7d-b598-771660342449","Minimising Cost by Dynamic Modelling of Aircraft Recovery in Disrupted Operations","Vos, H.W.M.","Lopes dos Santos, B.F. (mentor); Curran, R. (mentor)","2015","","Dynamic Modelling; Aircraft Recovery; Airline Recovery; Recovery Operation; Airline Disruptions; Disruption Management","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Operations","","Air Transport and Operations","",""
"uuid:da69d1cf-3274-466f-bbc2-573f571d154e","http://resolver.tudelft.nl/uuid:da69d1cf-3274-466f-bbc2-573f571d154e","Human-Operator Identification with Time-Varying ARX Models","van Grootheest, H.A.","Mulder, M. (mentor); van Paassen, M.M. (mentor); Pool, D.M. (mentor)","2017","The time-varying adaptation ability of human operators in basic manual-control tasks is barely understood. Most identification methods do not explicitly take into account any time variations. An identification procedure based on both batch and recursive autoregressive exogenous (ARX) models is presented for capturing the operator's controlled-element adaptation in compensatory tracking tasks. The operator's time delay was assumed to be constant and estimated beforehand. Conditions with constant controlled-element dynamics, matching recent experimental work, and gradual and sudden transitions in the controlled-element dynamics were considered. This study introduces a procedure to fine-tune forgetting strategies for these different conditions and for different remnant intensities. Both the use of a constant scalar forgetting factor λ and a constant forgetting matrix Λ, containing separate forgetting factors for each ARX-model parameter, was analyzed. Batch ARX-model identifications applied on conditions with constant dynamics, indicate that a high bias results when the operator's remnant is not coupled to the linear operator dynamics. By means of Monte Carlo simulations, an optimal forgetting factor is found for all conditions. For the human-operator model considered, the use of a forgetting matrix did not result in an improvement over the use of a scalar forgetting factor. An evaluation of real experimental manual-control data shows that the method has potential to capture the operator's adaptive control characteristics.","ARX model; forgetting factor; human operator; manual control; recursive least squares; time-varying system identification","en","master thesis","","","","","","","","2022-04-10","Aerospace Engineering","Control & Operations","","","",""
"uuid:b5b2b94b-3982-4457-a56f-51b5b3574f51","http://resolver.tudelft.nl/uuid:b5b2b94b-3982-4457-a56f-51b5b3574f51","Analysis of the Sun-Earth Lagrangian environment for the New Worlds Observer (NWO)","Deccia, C.M.A.","Noomen, R. (mentor)","2017","Exoplanets have been detected for more than 15 years. In the vast majority of instances, this has been accomplished through indirect observation. Such methods include among others the observation of radial velocity, transit photometry, and timing variations. These techniques allow for the vast majority of exoplanet detections up to date. An example for a very successful detection that has been achieved recently is the TRAPPIST-1 system. Indirect methods like these can provide us with estimates of a planet’s size and orbit for Earth-like planets. Yet, when we would like to detect life outside our Solar System, the fact alone that a planet lies in the habitable zone and that it has the right size is not a guarantee, but an indication of possible habitability. In order to have absolute certainty, a direct analysis of the atmosphere is needed. Direct observations would allow for a first-hand spectroscopy of the atmosphere in order to search for bio-signatures. These bio-signatures are markers created through biological processes and are indicative of life. Such elements include oxygen, ozone, nitrous oxide and methane. In order to allow for direct observations of Earth-like exoplanets, the New Worlds Observer (NWO) has been proposed as part of NASA Innovative Advanced Concepts (NIAC). NWO is a space-based observatory that will search for Earth-like planets that are located in the habitable zone in neighboring stellar systems. NWO consists of two spacecraft: a 4 m aperture-diameter diffraction-limited telescope and an occulter, called Starshade, which is 50 m in diameter. These spacecraft are located thousands of kilometers apart. This thesis discusses an analysis of the behavior of a satellite pair to be used for a preliminary observation campaign design for the NWO mission concept. In this concept, the two NWO spacecraft are positioned in Halo orbits about the Sun-Earth L2 point. This study demonstrates a novel method that may be used to redirect NWO’s observation vector from one star to another using dynamical systems theory, taking advantage of the non-linear dynamics around L2. To analyze the sensitivity of this method variations of the given constraints have been explored and analyzed.","New Worlds Observer; Starshade; Telescope; Exoplanet; Dynamical systems theory; Lagrange; Free drift","en","master thesis","","","","","","","","2017-06-07","Aerospace Engineering","Space Flight","","","",""
"uuid:e704e8aa-2371-437b-8de9-80b3b7067241","http://resolver.tudelft.nl/uuid:e704e8aa-2371-437b-8de9-80b3b7067241","Fault-Tolerant Design of a Pumping Kite Power Flight Control System","Friedl, F.","Messnarz, B. (mentor); Schmehl, R (mentor)","2015","This master thesis results from the project KitePower 2.0, a cooperation of Delft University of Technology and Hochschule Karlsruhe University of Applied Sciences. The aim of this project is to increase the technology readiness level of a system developed in Delft for converting the kinetic energy of wind into electrical energy. To do so, a tethered airfoil is used to drive a generator on the ground by reeling the tether off a drum while flying the foil in crosswind patterns in the downwind area of the ground station. The introductory chapter of the document at hand takes a closer look at this concept and briefly discusses its advantages and disadvantages. The subsequent part deals with the individual system components in detail. A special focus is put on certain software components such as the flight control system, the realtime simulation environment and its mathematical models. After their introduction, the most important components are assessed regarding the effect on the entire system in case of their failure. For this purpose a Failure Mode and Effect Analysis as well as a Fault Tree Analysis are performed. On the basis of these methods the faults and failures of further interest for this thesis are defined. In order to enable the system to recognize certain failures and initiate appropriate countermeasures a health supervisor is implemented and its abilities are discussed. Furthermore its two core classes are presented and their methods for fault detection are described. Another major part of this thesis is the development of the above mentioned automatic countermeasures. Chapter 5 presents these procedures and deals with their behavior in detail. Finally using simulations the health supervisor’s ability to detect failures as well as the countermeasure’s effectiveness is discussed. The very last chapter draws a conclusion and gives an outlook to possible future developments.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:003f8d30-11eb-4823-9143-1644ab74fb29","http://resolver.tudelft.nl/uuid:003f8d30-11eb-4823-9143-1644ab74fb29","Radar-based landing system for uncontrolled flights: Modifying a collision avoidance radar for synthetic aperture imaging","Baardman, L.","Hoekstra, J.M. (mentor)","2016","","","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:f1bc854a-36f9-4401-a892-2313e4022ea8","http://resolver.tudelft.nl/uuid:f1bc854a-36f9-4401-a892-2313e4022ea8","Evolving Systems Approach to the Attitude Control of a Large-Space-Debris Removal Spacecraft","Habets, J.M.G.","Mooij, E. (mentor)","2015","Space debris has become a major issue for the space industry over the last couple of years. The increasing number of uncontrolled objects in space increases the chance of collision with a spacecraft. The unexpected loss of contact with ENVISAT, the European Space Agency’s largest environmental spacecraft, added one more piece of debris to the list. It also sparked ESA’s interest in the active removal of space debris. Numerous removal methods are being investigated, one of which uses a chaser spacecraft that will attach itself to the debris by means of a robot arm and tentacles and will then perform a series of braking manoeuvres to re-enter the Earth’s atmosphere. The proximity operations require an accurate attitude control system. In this thesis, these operations have been divided into three phases: an unconnected phase in which the chaser spacecraft synchronises its motion with that of the (spinning) target debris; a semi-connected phase, where the robot arm and tentacles form a flexible connection between the chaser and target; a connected phase, where the two spacecraft are assumed to be rigidly attached to each other (and form a stack). The objective of this thesis is to investigate the stability and controllability of the system in these three phases. Because the system changes in configuration during its mission, it can be classified as an Evolving System; a system with actively controlled components that ""mate"" to form a single connected system. The connection between components becomes stronger during the evolution and can be represented by connection forces and moments. In this thesis, the connection is modelled as a rotational spring and damper acting between the chaser spacecraft and ENVISAT. By developing a representative simulator environment the stability and controllability of the system is assessed. Two major parts of the simulator comprise the attitude control algorithms and control actuators. The latter consists of a Reaction Control System, reaction wheels, and a control allocation algorithm. The attitude control algorithms that are investigated are a Linear Quadratic Regulator and a model reference adaptive controller. A linear stability analysis of the system showed that the system remains stable during its evolution when the chaser is actively controlled. This is partly because the motion of the chaser has little effect on the motion of ENVISAT due to the large size difference between the two spacecraft. However, for a system with equally sized spacecraft, the linear stability analysis showed that instability can occur. Furthermore, in stack configuration, a gravity-gradient stable attitude was found when the minor axis of the system is parallel to the Earth radial. Moreover, for a suitable deorbit attitude and an unobstructed view to the Earth, the only stable attitude is one which has a roll angle of -90 deg. Next, results of the nonlinear simulations revealed that the combination of reaction wheels and attitude thrusters gives worse performance than when only thrusters are used. This is because the reaction wheels are too small to cope with the constantly changing motion of ENVISAT. Second, for the unconnected phase, both the LQR and adaptive controller are able to synchronise the motion of the chaser with ENVISAT. However, the adaptive controller is not able to do this for all possible initial target rotations, whereas the LQR is. Third, the effect of the connection between ENVISAT and the chaser on the stability of the system is very small and both controllers are able to control the system. Fourth, the adaptive controller shows unacceptable performance during the control of the stack, because of the large difference between the reference model for which the adaptive controller was tuned and the actual system. Using a second reference model for the connected phase could improve the performance of the adaptive controller.","attitude control; space debris; adaptive control; evolving systems; ENVISAT","en","master thesis","","","","","","","","2017-04-06","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:7b305772-db45-431a-a431-3799e2cf0f20","http://resolver.tudelft.nl/uuid:7b305772-db45-431a-a431-3799e2cf0f20","Boundary Layer Ingestion: Theoretical and Experimental Research","Hartuç, T.","Gangoli Rao, A. (mentor)","2015","In this thesis both Wake Ingestion (WI) and Boundary Layer Ingestion (BLI) configurations have been investigated and analyzed with respect to their application to aircraft design. WI and BLI in the context used here means positioning the engine such that it ingests boundary layer fluid for the purpose of saving shaft-power. This research compares propulsors in free-stream, WI and BLI configurations for their shaft-power savings. The power elements present in these configurations are identified theoretically using the Power Balance Method (PBM) and quantified experimentally by using Particle Image Velocimetry (PIV). Also, these different configurations are compared using non-dimensional parameters such as thrust-power coefficient and propeller efficiency. This is accomplished by integrating different instruments able to capture the relevant physical phenomena such as thrust, torque and Rotations Per Minute (RPM). These measurements are conducted in the low-speed wind-tunnel facility of Delft University of Technology. The aim is to experimentally quantify the increase in propeller efficiency for WI and BLI configurations. In order to properly compare the three configurations, these are tested in two different wind-tunnel conditions; ’equilibrium’ and ’constant-speed’. In the equilibrium case, propulsor thrust is set identical to body drag for varying wind-speeds whereas the constant-speed case requires the wind-speed to be fixed and propulsor thrust to vary. The main finding is that a propulsor in WI configuration saves 9% shaft-power w.r.t. an identical propulsor in free-stream configuration under identical net-force conditions. This power saving is more prominently present in BLI configuration where 18% power saving is measured. This measured power saving is due to the fact that the propulsor is immersed in the slower moving wake. The propulsive efficiency, which is different from propeller efficiency, can generate values that exceed 100% in WI and BLI configurations. Therefore, a different definition of efficiency for a wake ingested propulsor is introduced. Using this new definition, the propulsive efficiency does not exceed unity for perfect wake filling configurations. The PIV analysis on the identified power terms shows that a limited amount of wake power is available for performance enhancement. The analysis also showed that pressure plays a significant role in these tightly integrated configurations which cannot be ignored. This insight can be used for the development of WI and BLI applications. These applications are needed as a mean to reduce fuel consumption for future aircraft.","Boundary Layer Ingestion; efficiency; propeller; wake ingestion; Particle Image Velocimetry","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:91020a79-bb59-46ef-aafc-2878eed822e3","http://resolver.tudelft.nl/uuid:91020a79-bb59-46ef-aafc-2878eed822e3","Design of a Deployable Structure for a Lunar Greenhouse Module","Vrakking, V.","Guo, J. (mentor)","2014","A design study was carried out at the German Aerospace Center (DLR) in Bremen, investigating the optimal structural design for a lunar greenhouse module. On account of the volume requirements of a lunar greenhouse and the volume constraints of modern launchers, the study has considered only inflatable and hybrid structures. A literature study was performed on the existing technologies and concepts of fully inflatable and partially inflatable (hybrid) space habitats and structures. Additionally, a review of the lunar environment was carried out and the impact on the lunar greenhouse module structure design was determined. Using system engineering tools, the structural requirements of the greenhouse module were defined. Concepts, such as a cylinder or semi-cylinder, were developed and assessed using an Analytical Hierarchy Process (AHP). A preliminary design of the structure was performed for the selected concept, a semi-cylinder with rigid end-caps and a flexible middle section. For the preliminary design, the gas retention properties as well as the micro-meteoroid and radiation shielding capabilities were designed and thermal and load-bearing properties of the structure were analysed. Additionally, a possible configuration of the greenhouse module interior was presented and interfaces between the rigid and flexible sections of the structure, as well as between the structure and other lunar base structures were discussed. Verification of the preliminary design calculations and the compliance with the requirements was carried out for the thermal and load-bearing structural properties, using the finite element analysis tool MSC Nastran. The final structure design is a semi-cylindrical hybrid structure with rigid end-caps, 20 m in length and with a 3 m radius and with a total mass of 43786 kg. Radiation protection is provided by covering the structure with regolith-filled bags. A total thickness of approximately 2,5 m of regolith needs to be applied to the greenhouse to provide sufficient protection for the astronauts and plants within during the envisioned two year mission lifetime.","","en","master thesis","","","","","","","","","Aerospace Engineering","Space System Engineering","","","",""
"uuid:fde729b0-5a1b-4c68-87fd-3debc95c3179","http://resolver.tudelft.nl/uuid:fde729b0-5a1b-4c68-87fd-3debc95c3179","Photovoltaic Concentrator Cells: Electro-Thermal Modelling And Experimental Analysis","Boven, R.V.T.","Kuiper, J.M. (mentor)","2017","An interesting concept related to photovoltaic energy is Concentrated Photovoltaics (CPV), in which sunlight is focussed on a PV cell through lenses and mirrors, thereby increasing the incident irradiance on the PV cell. Solar concentration is proven to not only increase the output power of PV cells, but also to increase the electrical efficiency of PV cells. This concept is expected to further push PV energy to the scale of MW power plants for large-scale energy production, and increase the power density of standalone PV modules on Earth and in space. Increasing the irradiation on a PV cell inevitably also increases the temperature of the PV cell due to thermal losses. Cell temperature has a negative effect on the output power and electrical efficiency of a PV cell, and given a high enough concentration ratio, may cause the PV cell to lose electrical efficiency and ultimately break down. Adequate cooling is therefore required for CPV systems to keep the PV cell in its optimal operating temperature range. For this purpose a model is proposed that simulates the output characteristics under influence of solar concentration and temperature variations, most notably the output power and electrical efficiency of a PV cell. The electro-thermal model is fundamentally based on the detailed balance model, which dictates that the absorbed and emitted photon flux must be equal in equilibrium conditions. From detailed balance, the absorption, recombination and photo-generation processes in a PV cell are determined, from which the Shockley-Queisser limit is deduced. This fundamental model is extended to the single-diode model, which serves as the ultimate baseline of PV simulation, taking into account cell temperature, concentration ratio and other internal PV cell factors. Sensitivity analyses on the single-diode model show that solar concentration indeed increases the output power and electrical efficiency. Taking into account solar concentration and temperature effects however, shows that the electrical efficiency drops by 4% points at a concentration ratio of 20, thereby confirming that without cooling, increasing the solar concentration on a PV cell will yield lower electrical efficiencies due to thermal effects. Laboratory experiments are conducted on an Emcore 3J gallium-arsenide PV cell (DUT) to verify the electro-thermal model. Baseline tests are conducted using a calibrated light source, and secondary tests involving a secondary light source are performed at controlled ambient and elevated temperatures. These results show that the model has a fit of 98.9% with respect to the verified specifications of the DUT PV cell at an ambient temperature of 25 ◦C. At an elevated cell temperature of 60 ◦C, discrepancies exist between the simulated single-diode model and test results. A new in-plane heat conduction concept developed by Airbus NL called Hiper is added to the test set-up to assess its suitability in conjunction with a heat radiator for PV cells. Hiper is a novel thin-film material particularly suited to spread heat effectively over a surface, from which it can be dissipated using a radiating material. Experimental results show that heat is spread slightly more effectively with Hiper, than in the same test set-up without Hiper, highlighting its heat spreading capabilities.","Photovoltaic concentrator cells","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","Space Systems Egineering","",""
"uuid:27776bdf-fffd-449a-86f8-a1a5f93b16aa","http://resolver.tudelft.nl/uuid:27776bdf-fffd-449a-86f8-a1a5f93b16aa","3D Solution Space-based Prediction of Air Traffic Control Workload","Somers, V.L.J.","Borst, C. (mentor)","2017","Air Traffic Control (ATC) workload is the main limiting factor for air traffic growth. Although predicting workload is important, a proper objective ATC workload metric is still not available. Previous research has shown that using the solution space diagram as a workload prediction metric is promising. This metric is based on the concept that ATC workload is inversely related to the size of the set of all available solutions. The current solution space metric however, does not incorporate altitude. In this thesis a 3D solution space metric is designed and evaluated. An experiment has been conducted to test the relation of the 3D solution space metric with workload and compare it to a conventional workload metric, the aircraft count, and a quasi-3D metric: the 2D layered solution space. Participants were required to separate air traffic on predefined flight routes, while rating their subjective workload at regular time intervals with an Instantaneous Self Assessment-based method. Weak correlations with workload were found for all tested metrics and no significant differences were found between them. Excluding aircraft that had been given a transfer of control did not yield a significant improvement. Although no significant differences were found, the 2D layered metric showed more promising results than the 3D solution space-based metric, indicating that air traffic controllers might think in 2D layers over fixed altitude ranges rather than considering the complete 3D physical solution space.","","en","master thesis","","","","","","","","2022-05-19","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:afca5f7f-d2d5-45ba-beec-bc6fec0a5f4b","http://resolver.tudelft.nl/uuid:afca5f7f-d2d5-45ba-beec-bc6fec0a5f4b","GMRES(m) with de ation applied to nonsymmetric systems arising from fluid mechanics problems","Dinkla, R.M.","Bijl, H. (mentor)","2009","The computational simulation of many engineering problems requires solving linear, sparse, systems of unknowns. Also in the field of aerodynamics, where discretization of equations governing ow problems produces these systems. Improving efficiency of iterative methods used for solving these systems decreases the costs of simulations and is therefore an important research area. The most important iterative methods for solving linear systems today are Krylov subspace methods. One way to accelerate convergence of these methods lies in eliminating the influence of specific problematic subspaces. This called deflation. The two main methods of deflation are preconditioning with a projector and by augmenting the Krylov subspace. Both these deflation types have been investigated in combination with GMRES, a popular Krylov subspace method, in order to better understand convergence behaviour of defeated problems. Some theoretical aspects are introduced and numerical experiments have been done. It was shown theoretically that deflation preconditioning and augmentation give identical convergence results when the deflation subspace is an eigenspace. Furthermore, the importance of not disturbing the Krylov subspace was emphasized. These aspects are both illustrated with an example. The numerical experiments were done using three types of deflation subspaces: eigenspaces, approximate eigenspaces and spaces spanned by algebraic vectors based on coarse grids over the physical domain of the problem. This third type is cheap to construct and has raised interest because it has shown to be very effective for SPD problems. The test cases in this work concern a convection-diffusion problem with varying convective strength and the ow around an airfoil. Eigenvectors associated with small eigenvalues are known to often hamper convergence and this was shown in the test cases as well. Coarse grid subdomain deflation showed to remain effective for the convection-diffusion problem, even when the nonsymmetry was decreased by increasing the strength of the imposed convection. This is because the new deated eigenspectra lie away from the origin. The cases concerning the ow around an airfoil only benefited from subdomain deflation in a limited number of cases. Therefore, subdomain deflation does not seem an effective method for this type of problems.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e3697d02-fe10-4510-b8d8-f8830461df41","http://resolver.tudelft.nl/uuid:e3697d02-fe10-4510-b8d8-f8830461df41","CFD simulations of the Galatea robot's flow field: Towards efficient and accurate simulations of turbulent flow on a dynamic mesh","Bergers, M.M.C.","Bijl, H. (mentor)","2010","Undulating Fin Propulsion (UFP) is used as alternative propulsion for bio-mimetic underwater robots. The Galatea robot uses UFP and is the focus of this study. To optimise the settings for its propulsive wave more knowledge is required about the flow field around Galatea. Computational Fluid Dynamics is used for the investigation of this flow field. The main goal of this thesis was to create an efficient and accurate numerical model to simulate the flow field around Galatea. Efficiency needs to be quantified in terms of speed and resources used. Accuracy has to be demonstrated through verification and validation. The ow around Galatea is incompressible, turbulent and unsteady (due to the propulsive fin motion).","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f6531921-ee06-4a8c-88f9-95a31a262797","http://resolver.tudelft.nl/uuid:f6531921-ee06-4a8c-88f9-95a31a262797","Improving the hydrodynamic performance of a combined Wells-Darrieus rotor","Soons, E.J.","van Bussel, G.J.W. (mentor); van Terwisga, T.J.C. (mentor); de Koning Gans, H.J. (mentor); Scheijgrond, P. (mentor)","2007","","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5684c665-a245-429c-b4d6-a580d09f3800","http://resolver.tudelft.nl/uuid:5684c665-a245-429c-b4d6-a580d09f3800","Optimization of Non-Planar Wing Aircraft Configurations: Accounting for Low Speed Mission Segments","Verhagen, B.M.","Voskuijl, M. (mentor)","2017","Air traffic is expected to grow over the next few decades, which will cause the global fuel consumption to increase. Reducing the drag of an aircraft will result in a reduction of the fuel consumption. Non-planar configurations may offer a solution to reduce the drag while maintaining the performance of today’s aircraft. The aim of this study is to identify the effect of using different climb and descent strategies on the planform optimization of non-planar wing configurations. In order to analyze these effects, a generic aero-structural model is developed, which combines a developed mission analysis model to assess the aircrafts performance over an entire mission profile. In this study, four aircraft configurations are considered: a planar configuration, a wing with winglet configuration, a C-wing configuration, and a box wing configuration. Using a gradient based optimization method, the configurations are optimized for minimum fuel consumption over an entire mission profile. The optimized box wing configuration offer fuel reductions up to 2% with respect to the planar configuration. The lift over drag ratio of the box wing is lower, but this is compensated for by its lighter wing mass. The C-wing has higher lift over drag ratios, but this does not compensate for the heavier wing mass. Therefore the C-wing results in a higher fuel consumption.","","en","master thesis","","","","","","","","2018-01-01","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:544d2eda-75f1-4533-98ca-f72aa38770b1","http://resolver.tudelft.nl/uuid:544d2eda-75f1-4533-98ca-f72aa38770b1","Aviation policy decision-making of I&M: An evaluation","Chindea, J.","Blom, H.A.P. (mentor)","2017","","","en","master thesis","","","","","","","","2027-03-16","Aerospace Engineering","Control & Operations","","Air Transport Operations","",""
"uuid:0dd55171-6768-4e46-b6cd-970eb912e2ac","http://resolver.tudelft.nl/uuid:0dd55171-6768-4e46-b6cd-970eb912e2ac","Aerodynamic Design Optimization of the MTT Radial Micro Turbine","Govindarajan, S.","Colonna, P. (mentor); Pini, M. (mentor); Visser, W.P.J. (mentor)","2015","Micro turbines are touted to become the prime system for the combined heat and power(CHP) applications in light of their significant advantages in terms of performance, size, costs and reduced CO2 emissions [1]. Micro Turbine Technology B.V. (MTT) is currently developing a 3KW recuperated micro turbine for such applications. Commercially available off the shelf turbocharger components are used since they provide high performance with relatively low costs since they are mass produced.The drawback in using these components is that they are manufactured for the automotive sector and inherently operate at different conditions than the MTT operating point. Here in lies an interesting scope for performance improvement by optimizing the turbine and within the current work the focus is on aerodynamic optimization of the radial inflow turbine used in the MTT system. This study is a follow-up from the recommendations provided in [2] and [3]. A goal driven optimization is performed on the rotor geometry using ANSYS DesignXplorer and a total of four design solutions were obtained. The most important findings from the response surfaces, sensitivity analysis from the optimization were: From the parametric sensitivity it was clear that all of the six design variables have a significant impact on efficiency. The exducer angles have the most predominant effect on efficiency with that of shroud larger than hub. All of the optimal candidates exhibited an increase in the total-to-total efficiency ranging from a minimum of 6.38 percentage points to a maximum of 7.90 percentage points as compared to the baseline geometry. This efficiency improvement was accompanied by an increase in mass flow rate with a minimum value of 69.15 g/s and a maximum of 73.51 g/s. These design solutions are then coupled with the diffuser domain to study the performance characteristics and the interaction between the components. The most important outcomes from these simulations were: The efficiency of the rotor drops by 3 percentage points on an average due to the additional pressure losses introduced when coupled with the diffuser. The diffuser performance has improved and the Cp experiences a maximum increase of 17.63 percentage points (Candidate D) and a minimum of 12.70 percentage points (Candidate B). The swirl coefficient for optimum diffuser performance is found at values close to 0.22. If the swirl coefficient is increased or decreased from this optimum, diffuser performance drops. The best design solution in terms of rotor efficiency and overall total-to-static efficiency is Candidate C. However it exhibits a poorer diffuser performance than the other optimal candidates. From this study, it is apparent that there is compromise between rotor and diffuser performance. The improvement in rotor efficiency( 1 Hz) disturbance forces, and their effects on the OPD. The internal disturbance forces are examined for the three subsystems which are believed to cause most mechanical vibrations. The frequency-dependence of the external disturbance forces is determined in LEO for a precursor interferometry demonstration mission, by Fourier-transforming the accelerometer data of the GRACE mission. These results, together with a literature survey on the space environment in L2, lead to an overall view on the order of magnitude of the high-frequency disturbance forces that can be expected on Darwin. In addition the micrometeoroid impacts are studied. The internal disturbance forces are found to be dominating. Their high-frequency component remains small but has still the same order of magnitude as the OPD-requirement of 5 nmRMS, for a 1 Hz control bandwidth. Also the micrometeoroid environment shows a possible threat for Darwin.","interferometry; Darwin; perturbations; space; formation flying","en","master thesis","TU Delft, Aerospace Engineering, Astrodynamics and Satellite Systems","","","","","","","","Aerospace Engineering","","","","",""
"uuid:78bc2287-dcbb-4bde-843b-3fa223bc0e53","http://resolver.tudelft.nl/uuid:78bc2287-dcbb-4bde-843b-3fa223bc0e53","Analysis of propeller slipstream effects on the directional stability using a potential flow model","Van Wonderen, N.J.","Vos, R. (mentor)","2017","","Propeller Slipstream Effects; Potential Flow Model; Parametric Approach; Propeller Aircraft; Directional Stability","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:3941938c-e684-4e31-8c31-7d6f0040f97c","http://resolver.tudelft.nl/uuid:3941938c-e684-4e31-8c31-7d6f0040f97c","The conceptual design of a safety system: For the 5MW Deepwind wind turbine","Chrysochoidis-Antsos, Nikolaos","van Bussel, G.J.W. (mentor)","2014","This research work proposes the initial design considerations of the safety system of the Deepwind offshore floating vertical axis wind turbine. Deepwind is a wind turbine model and prototype development project under the umbrella of the 7th European Framework Programme. The safety system is one of the aspects of this project and it is dealt within this Thesis work. Safety is one of the most important features that modern wind turbines should include. Statistics and industrial experience have indicated to the regulation organizations (e.g. IEC,DNV) to add safety systems in the complex electromechanical system of a wind turbine. The most crucial safety feature is the over-speeding control. Usually the controller functions alleviate this problem but an additional safety level is more than necessary to avoid irreparable incidents. This safety feature has been developed within the scope of this Thesis. Therefore, the major task is the definition and design of the safety system functions. This task was conducted in the context of the Conceptual Design method. Several possibilities were investigated. This search led to systems using the aerodynamic and hydrodynamic principles of operation. Many aspects were taken into account concerning the functionality and compatibility of these safety systems. These aspects were addressed from literature review and generation of engineering models in MATLAB. Finally, through multi-criteria analysis, which is one of the tools of Conceptual Design, all the systems were compared and a solution was formulated with the initial design configurations for further development. The proposal of this Master Thesis is to sink the wind turbine system inside the sea, by adding seawater into the spar buoy in an effective time response. Consequently, the blades of the wind turbine hit the seawater and thus create enough drag forces to reduce effectively the rotational speed. The particular wind turbine characteristics make this solution the most promising, as presented through the whole process. This report proposes the initial design characteristics but also suggests further steps on the design process of the safety system.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","Sustainable Energy Technology","",""
"uuid:2e1177d2-9fd0-416b-b90a-2866600d8014","http://resolver.tudelft.nl/uuid:2e1177d2-9fd0-416b-b90a-2866600d8014","Sensitivity Analysis of Airborne Wind Turbine Design Variables: Using trajectory optimization","Van Alsenoy, Thomas","van Bussel, G.J.W. (mentor); Schmehl, R. (mentor)","2014","","Windenergy","en","master thesis","","","","","","","","2025-01-01","Aerospace Engineering","Wind Energy","","","",""
"uuid:09f5dfed-5185-401c-9bbd-065130fe2bda","http://resolver.tudelft.nl/uuid:09f5dfed-5185-401c-9bbd-065130fe2bda","Dimension-adaptive sparse grid for industrial applications using Sobol variances","Desmedt, S.G.L.","Dwight, R. (mentor); Shoeibi Omrani, P. (mentor)","2015","The area of interest for this study is the field of uncertainty quantification in computational fluid dynamics. The goal is to contribute to a new method to perform uncertainty quantification analyses for industrial, computationally expensive CFD simulations. To this end, an adaptive grid refinement method is developed. The existing sparse grid procedure introduced by Smolyak is combined with Clenshaw-Curtis quadrature rules. Starting with a low level grid, more points are added based on the values of the Sobol variances, which are estimated values. The Sobol variances provide an indication of the importance of each variable and interactions between variables. The method is applied to an industrial atmospheric flow case, where a heavy gas is released upstream of a barrier. The quantity of interest is the effect distance, the distance from the barrier where the molar concentration drops below 1 percent, which is important for safety. The results show that, for this case, the new adaptive grid refinement method reduces the computational cost to one third of a conventional sparse grid, while providing similar results.","Sparse grid","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics and Wind Energy (AWE)","","Aerodynamics","",""
"uuid:1a8bbab8-bc9c-4331-935d-d278508755f7","http://resolver.tudelft.nl/uuid:1a8bbab8-bc9c-4331-935d-d278508755f7","Self-healing of deformation-induced defects in Fe-based alloys using positron annihilation techniques","Gramsma, M.E.","Van Dijk, N.H. (mentor)","2015","This thesis investigates the self-healing mechanisms of deformation-induced defects in ferritic Fe-Au(-B-N) and Fe-Mo alloys, by segregation and precipitation of Au elements and Fe2Mo compounds. For this purpose, cyclic tensile tests on the Fe-Au(-B-N) alloys are conducted interrupted with isothermal ageing steps at 550 °C. Coincidence Doppler Broadening (CDB) measurements are performed to study the defect evolution and precipitation behaviour occurring at these defect sites, to clarify the correlation between precipitation and strain-induced defects. Using this technique, the Fe-Mo samples are studied for various ageing times up to 64 h. These measurements are conducted with 8% deformed and undeformed samples, to study the influence of dislocations on the Fe2Mo precipitation. Furthermore, Vickers hardness tests are conducted on undeformed and 8 % deformed Fe-Mo alloy samples for various ageing times, as well as creep tests for the Fe-Mo and Fe-Au(-B-N) alloys in combination with SEM observations. Next, diffusion-based finite element model calculations are performed on filling of a creep cavity for the Fe-Mo alloy. It is found from the model that the filling of a creep cavity on a grain boundary can be well compared with the growth model of a precipitate on a grain boundary. From the CDB measurements, it is found for the Fe-Au(-B-N) alloys that in a major part of the deformation-ageing cycles healing takes place after introducing defects. Being consistent with previous research [1], it is found that the addition of B and N to the Fe-Au alloy retards the Au precipitation. For the Fe-Mo alloy, it is found from CDB measurements that the segregation and precipitation of Fe2Mo is enhanced by induced dislocations and other defects. The creep lifetime of this alloy is improved compared with that of the Fe-Au alloy, together with a higher ductility. Based on the CDB measurements, supported by the creep measurements and SEM studies, it is shown that Mo solutes have a tendency to segregate selectively to dislocations and open-volume defects. The site-selective precipitation makes Mo a promising alternative for Cu and Au to act as an efficient self-healing agent for deformation-induced defects in Fe-based structural alloys for use at elevated temperatures.","Self-healing materials","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","Novel Aerospace Materials","",""
"uuid:1b88a17d-e821-4ee1-b0fd-9c17fdee2558","http://resolver.tudelft.nl/uuid:1b88a17d-e821-4ee1-b0fd-9c17fdee2558","Design of residual-based unresolved-scale models using time-averaged data","Navarro Hernandez, L.C.","Hulshoff, S.J. (mentor)","2015","The Large Eddy Simulation of high Reynolds number wall-bounded flows, has grid refinement requirements in near-wall regions similar to those of DNS. The feasibility of such computations is restricted by their elevated costs and therefore alternate solutions must be employed. While several methods to couple LES and RANS have been proposed, most of them employ complicated techniques to combat issues that stem from the inconsistencies introduced by the arbitrary nature of the coupling methods. The aim of this research is to propose a consistent hybrid framework based on a Variational Multiscale Method (VMM) formulation of the Navier-Stokes equations for turbulence computation; where a residual-based algebraic expression for an SGS model will be employed as a coupling term. While, the final solution will be obtained under an LES scheme, the SGS model will contain information drawn from reference data in an overlapping domain. Since the VMM results in an SGS model which depends on the large-scale residual, the coupling will effectively vanish within sufficiently resolved regions without the need of additional controlling terms. The expected result is therefore to demonstrate that reference-data-enriched LES is possible with a solid understanding of the behavior of the proposed SGS models as a basis for future work.","Variational Multiscale Method; Turbulence; LES","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:2c98b1e4-4bd5-423e-a756-16b815f8ec9d","http://resolver.tudelft.nl/uuid:2c98b1e4-4bd5-423e-a756-16b815f8ec9d","Stability analysis for two-phase pipe flow","Bakker, M.","Van Zuijlen, A.H. (mentor)","2016","","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:bdaba329-d62e-4257-88a0-62100b28c015","http://resolver.tudelft.nl/uuid:bdaba329-d62e-4257-88a0-62100b28c015","The 3D separation behaviour of a micro-ramp controlled oblique shock-wave reflection: An experimental Investigation","Nayak Kallarbail, S.","Van Oudheusen, B.W. (mentor); Schrijer, F.F.J. (mentor); Giepman, R.H.M. (mentor)","2016","Oblique Shock-Wave Reflections or Shock Wave-Boundary Layer interactions (SWBLI) are complex phenomena which commonly occur in high speed flight. SWBLIs can have catastrophic consequences on the aircraft due to shock induced separation and unsteadiness of the interaction. These adverse effects can be mitigated by manipulating the boundary layer, either before it enters the interaction, or in the interaction region itself. Micro-ramp vortex generators or micro-ramps have been identified as promising boundary layer control methods in supersonic engine intakes. They are small ramp devices with heights less than the boundary layer thickness (typically 50% of boundary layer thickness). It is known that, micro-ramps generate a counter-rotating vortex pair, due to which a fuller and more separation resistant boundary layer is obtained upstream of the SWBLI. They successfully prevent separation at their centrelines and their effectiveness reduces away from their centrelines. Since a micro-ramp generates a highly 3D flow, the main aim of this study is to quantify the 3D velocity fields in the micro-ramp controlled interaction. Further, this study is motivated by the fundamental question whether the total volume of separated flow in the interaction is reduced by employing micro-ramp control. The results from tomographic-PIV experiments confirm that micro-ramp control has a beneficial effect on SWBLI in reducing separation. For the experimental conditions and micro-ramp geometry used in this thesis, the total volume of separated flow is reduced to 31% compared to the interaction without control. Further, the maximum separation probability is also reduced by using micro-ramp control, with the largest reductions occurring along the micro-ramp centreline. Additionally, the findings indicate that a moderately negative correlation coefficient exists between separation bubble sizes at spanwise stations on either side of the micro-ramp centreline. This indicates that the separation bubble size at a particular spanwise location is coupled to its size at another spanwise location in the micro-ramp controlled interaction. Along with the 3D velocity fields in the interaction, these results extend the knowledge on micro-ramp control significantly. It is conjectured that the spanwise correlation between the separation bubble sizes may play an important role while using micro-ramp arrays for applications in supersonic engine intakes. Therefore, an immediate possible investigation would involve studies of 3D effects of micro-ramp array control and the spanwise correlation of the separation bubble sizes.","shock wave-boundary layer interactions; shock waves; vortex generators; micro-ramp vortex generators; shock induced separation; tomographic-PIV","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:762b54d1-fec3-4b83-8c48-1ab1d4d15789","http://resolver.tudelft.nl/uuid:762b54d1-fec3-4b83-8c48-1ab1d4d15789","Structural Design and Optimisation Tool for Large Composite Ships","Ten Veen, M.","Benedictus, R. (mentor); Bergsma, O.K. (mentor); Saunders, G. (mentor); Notenboom, R.P. (mentor); Morel, L. (mentor)","2016","Structural ship design is gradually changing from the use of rule-based design methods to more rational-based design methods. The rational-based design methods are entirely based on structural theory and computer-based methods, while the rule-based design methods are formed by prescriptive rules from classification societies. In rational-based design methods structural analysis and design optimisation are combined to create the optimum structural design, in both weight and costs. This thesis explores a rational-based design method to be used for the design of large composite ships, including the interaction between hull and superstructure. The created design method is a multi-level design method, divided in the simulation of the global structural response and the design and analysis of local substructure panels. The global structural response of the ship is simulated by a two-dimensional finite element model. On the local level, the substructure panels are assessed by separate failure mode analyses. Here the load cases of the panels are based on the global structural response and minimum pressure requirements. The chosen distinction between global and local design gives both an efficient as an accurate design method. Part of the design method is implemented into a rational-based design tool. The verification of the rational-based design tool shows that a minimum amount of elements in both length and height direction in the finite element ship model is needed to get accurate results with respect to analytical calculations. The design tool is consequently used on a specific ship design of a mine countermeasures vessel. The worst case static wave scenario is created for both the sagging and hogging load cases. The global static analysis provides an accurate simulation of the ship in equilibrium condition and the stress distributions can provide valuable insights about formed stress concentrations. The effective and non-effective hullsuperstructure interaction can be implemented, but further improvements in the design tool are needed to analyse the interaction in more detail. A comparison with an existing rule-based design tool is made to check a specific ships structural design. Here the results from the rational-based design tool show that the structural design is insufficient, while the results from the rule-based design tool do not. This is the case even though the load case in the rule-based design tool is more conservative then in the rational-based design. This shows the relevance of rational-based design methods in future ship design. Overall the design tool has shown an accurate simulation of the ships global structural response and the detailed local failure mode analyses provides the stiffness and strength state of the substructure panels on the local level. Implementation of the remainder of the design tool is needed to complete the design and analysis of large composite ships, including the hull-superstructure interaction.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:3e777823-ef53-4ac7-b246-cd7ff7b39487","http://resolver.tudelft.nl/uuid:3e777823-ef53-4ac7-b246-cd7ff7b39487","Kiteplane Flight Dynamics: Stability and control analysis of tethered flight for power generation purposes","Terink, E.J.","Ockels, W.J. (mentor); Breukels, J. (mentor); Voskuijl, M. (mentor); Schmehl, R. (mentor)","2009","Kite power has only recently gained serious interest from industry and scientists, but the technology is advancing fast through various projects around the globe. The prospect of cheap wind energy is appealing to investors in the current political and social climate. One of the promising concepts is the Laddermill, which features a tether that is pulled by aerodynamic lifting bodies to drive a generator for electricity production. The Laddermill operation consists of an upstroke and a downstroke. With the lifting bodies controlled in such a way that they maximize the tether tension in the upstroke and minimize the tether tension in the downstroke, net energy can be produced…","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace for Sustainable Engineering and Technology","","","",""
"uuid:51041c5c-66c2-4d47-bf20-91459a538f7d","http://resolver.tudelft.nl/uuid:51041c5c-66c2-4d47-bf20-91459a538f7d","A New Methodology for the Development of Simulation Workflows: Moving Beyond MOKA","Chan, P.K.M.","Van Dijk, R.E.C. (mentor)","2013","One of the main challenges in Multi-disciplinary Design Optimisation (MDO) is the interoperability of heterogeneous simulation tools. Some researches have reported that, due to these interoperability issues, only around 20% of the product development time is spent on analyses and creative design tasks. Clearly, there is a lot to gain, when it comes to improving this figure. Key to the success of MDO is Knowledge Based Engineering (KBE) and Simulation Workflow Management (SWFM) technologies. However, developing KBE and SWFM applications requires a substantial amount of programming knowledge and expertise. Due to these constraints, the technologies are less accessible to non-programmers. Additionally, there is an increased risk that applications may become black boxes when it is not clear what knowledge went into the application. This complicates sharing and reusing knowledge in future projects. Therefore, a methodology is needed to avoid these complications. MOKA, the most well-known methodology for developing KBE applications, focuses on the KBE side rather than SWFM side of design systems. Therefore, a new methodology is developed that covers SWFM. Meanwhile, the aim is to reduce the amount of required expertise for modelling simulation workflows. The methodology presents new step-by-step instructions to guide engineers in the modelling process. Furthermore, the methodology introduces new forms, the Business Process Model and Notation (BPMN), and an N2 notation to capture and structure process knowledge. This knowledge is then formalised (i.e. translated to a format which is closer to computer language) before the workflow is automatically generated in Optimus, a SWFM system for building executable workflows. For this purpose, a new integration framework has been developed, based on the Integrated Design and Engineering Architecture (IDEA), which evolved from the Design and Engineering Engine (DEE). The new framework couples a Knowledge Base (KB), product (KBE) and process (SWFM) tools. Reducing the required expertise is achieved by introducing High-Level Activities (HLA). Capturing lower-level knowledge in these HLAs allows for inexperienced engineers to model workflows at a higher abstraction level. Meanwhile, a new parametric high-level workflow has been designed, that enables engineers to optimise KBE product models without actually modelling a workflow. Both the HLAs and the parametric workflow are used in several use cases involving a packaging design optimisation and an MDO workflow for thermoplastic injection moulding. In the end, this work has delivered tools, methods, and a framework that increases transparency of SWFM applications, saves development time, and reduces required expertise to model simulation workflows.","Knowledge Based Engineering (KBE); Simulation Workflow Management (SWFM); automation; knowledge engineering; methodology; MOKA; Multi-disciplinary Design Optimization (MDO); engineering design framework; automatic workflow generation","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:59d18aa3-dbcb-4252-b1cb-eaf13f0059bf","http://resolver.tudelft.nl/uuid:59d18aa3-dbcb-4252-b1cb-eaf13f0059bf","Development of a Knowledge-Based Engineering Application to Support Conceptual Fuselage Sizing and Cabin Configuration: Towards a Next Generation Multi-Model Generator","de Jonge, R.L.A.","la Rocca, G. (mentor)","2017","The department of Flight Performance and Propulsion at the Faculty of Aerospace Engineering has developed the Design and Engineering Engine (DEE) concept to supportMultidisciplinary Design Optimization (MDO) of complex products. The goal of the DEE is to accelerate design, analysis and optimization by automating repetitive and non-creative design activities. A central part of the DEE is theMulti-Model Generator (MMG), a Knowledge-Based Engineering (KBE) application that provides a generative modeling capability. Over the years several aircraftMMGs have been developed to support aircraftMDO. The previous aircraft MMG was built using the KBE system GDL. Over the years, several limitations of the fuselage model included in the GDL MMG, called DARfuse, have become apparent. Therefore, this thesis describes research done into the development of a new parametric fuselage model to be included in the next generation Multi-Model Generator, currently under development within the department of Flight Performance and Propulsion. The new fuselage model is called ParaFuse and has been developed using the KBE system ParaPy. The scope of ParaFuse is limited to conventional, low-wing, passenger aircraft certified under CS 25 airworthiness requirements. The first goal of the thesis was to develop a new parametric fuselage model. The implemented modeling approach uses longitudinal guide curves and fuselage cross sections to generate the final fuselage geometry. A separate parameterization approach is taken to provide a smooth nose end cap. Furthermore, a parameterized wing-body fairing has been implemented in ParaFuse. As a second goal, an inside-out fuselage sizing and cabin configuration method has been developed and implemented to automate the fuselage layout and sizing process. The inside-out design method can be used to automatically generate the outer fuselage geometry and interior components based on payload requirements posed by the user, such as passenger capacity and cargo type. The inside-out sizing method has been validated by reconstructing several reference aircraft using ParaFuse. On average, the error of the external dimensions of the resulting fuselages is 2% with respect to the dimensions of the fuselage of the actual aircraft. Thus, it can be concluded that the implemented inside-out sizing method can be used to accurately size the fuselage of conventional, low-wing, passenger aircraft. In addition, an outside-in cabin configuration method has been implemented in ParaFuse. This method can be used to perform cabin (re)configuration studies of fuselages with fixed external dimensions. ParaFuse is able to generate the fuselage models, including cabin interiors, within 20 seconds. This allows the user to rapidly evaluate a large number of different fuselage models. To demonstrate the functionalities of the application, two case studies are presented in this thesis. First of all, ParaFuse has been used to generate several cabin designs for the AAR cruiser, which has been developed by the faculty as part of the RECREATE project. A second case study has been performed to evaluate the fuselage design of a regional turboprop aircraft. The development of ParaFuse, together with the implemented fuselage sizing and cabin configurationmethods, described in this thesis is a step towards a next generation aircraftMulti-Model Generator.","Knowledge-Based Engineering; Multidisciplinary Design Optimization; Aircraft Design; Fuselage","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Flight Performance and Propulsion","",""
"uuid:89a04724-2a02-4f43-8c0d-e42afcb989d1","http://resolver.tudelft.nl/uuid:89a04724-2a02-4f43-8c0d-e42afcb989d1","A Comparative Analysis of the Two-Bladed and the Three-Bladed Wind Turbine for Offshore Wind Farms","Paul, A.J.","van Bussel, G.J.W. (mentor); Zaaijer, M. (mentor); Diepeveen, N. (mentor); Ashuri, T. (mentor)","2010","Background: As the installation of offshore wind farms continues to increase, the need to optimize on costs involved is a constant factor in the industry. In this regard, research into the two-bladed rotor has garnered some interest in the recent past, to see if the optimum cost can be shifted in the favor of the two-bladed wind turbine. Objective: The objective of this thesis was to determine the costs of energy delivered by a two-bladed wind turbine and a three-bladed wind turbine and to determine which turbine’s cost is lower. Energy cost was treated as the main discerning factor between the turbines. Method: Two concepts were defined; the two-bladed wind turbine and the threebladed turbine. For the three-bladed concept two cases were considered; one with a design tip speed ratio equal to that of the two-bladed concept and another with a design tip speed ratio lower than the first case. Only the rotor and the support structure were designed. For the rotor, Delft University airfoils were used. The Blade Element Momentum theory was used to design the rotors and to obtain the rotor power and thrust. Support structures were designed based on the Rayleigh method for stepped piles. Bladed 3.80 was used to determine fatigue damage of the rotors and support structures. Components in the nacelle were not designed but their masses were estimated using scaling relations. These masses along with rotor and support structure masses were translated into Euro’s using cost factors obtained from literature. An offshore site roughly 70km from shore was selected and hundred of these designed turbines were hypothetically installed at this site. Cost of installation and electrical infrastructure was obtained from data available. From this and the rotor and support structure costs the investment cost was obtained. The Annual Energy Yield of the turbines was also calculated. These, along with operation and maintenance costs were used to calculate the energy cost. Main Results: From the design iterations it was seen that the energy cost of the twobladed turbine was slightly lower than that of the three-bladed concept with a lower design tip speed ratio. Another important result of this report was that a three-bladed turbine with a tip speed ratio equal to that of the two-bladed turbine gave the lowest energy costs. It was also seen that the energy yield of the two-bladed concept is lower than that of the three-bladed concept and support structure costs for the two-bladed concept is higher.","Windenergy; wind turbine; two-bladed; three-bladed; rotor; tip speed ratio; blade; support structure; nacelle; LPC","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","Sustainable Energy Technology","",""
"uuid:6478003a-3c77-40ce-862e-24579dcd1eab","http://resolver.tudelft.nl/uuid:6478003a-3c77-40ce-862e-24579dcd1eab","Dynamic modelling of a flexible kite for power generation: Coupling a fluid-structure solver to a dynamic particle system","Geschiere, N.H.","van Bussel, G.J.W. (mentor); Schmehl, R. (mentor); Tiso, P. (mentor)","2014","This thesis investigates the dynamic modelling of a kite power system. The goal was to create a model that is able to capture the complex flight dynamic behaviour of a kite. A proof-of-concept already existed. From that work the steady fluid-structure interaction (FSI) module, using finite elements (FE), was used and coupled to a bridle and tether model. The bridle and tether model is based on an existing tether model that used spring-dampers. The tether model was then extended to include the full bridle system and steering due to line deflection. The focus thus lies in their coupling. An interface was created to couple the two models, such that the dynamic bridle model calls the FSI model at the end of every time step. For stability reasons the ends of the bridles were included in the FE model, so that high forces perpendicular to the bridle lines are avoided. In addition, spring-dampers with a low stiffness but high damping were placed between the bridle boundary points. Yet, due to a lack of aerodynamic damping in the FSI module, the kite proved to be unstable. Therefore artificial damping was implemented, based on the differential between the bridle particles' individual velocity and the wing's overall velocity. This resulted in a model capable of simulating the dynamic flight behaviour of a kite power system. This was compared to the empirical turn rate law, which was tuned to KitePower's technology demonstrator. It was found that the turn rate of the simulation matched qualitatively, but not quantitatively, due to the inevitable need for artificial damping.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","","",""
"uuid:d3d3be57-0136-4258-95b5-a97e70a9d167","http://resolver.tudelft.nl/uuid:d3d3be57-0136-4258-95b5-a97e70a9d167","Deployable Space Telescope: Optimal Boom Design for High Precision Deployment of the Secondary Mirror","Lopes Barreto, J.W.","Kuiper, J.M. (mentor); Dolkens, D. (mentor); Stam, D.M. (mentor); Gill, E.K.A. (mentor); Cruijssen, H. (mentor)","2017","The use of deployable structures for space telescopes has the advantage of enabling options to improve their optical performance and reducing the launch volume. The Deployable Space Telescope (DST), which is currently developed by the Space Systems Engineering (SSE) department, will make use of a high precision deployable structure to extend the secondary mirror 1.3 m from the primary mirror. In the initial design of the telescope, three articulated booms were chosen as the deployable mechanism between the two mirrors. This design, however, had a high mass and a low deployment ratio. In order to reduce the mass and increase the deployment ratio of the mechanism, while maintaining the required deployment accuracy, this research project has focused on investigating and analyzing alternative deployable structures and materials. Furthermore, the interface between the optimal deployable mechanism and the DST system has been designed.","satellite; deployable; telescope; booms; structures; articulated; CTM; space","en","master thesis","","","","","","","","2022-05-19","Aerospace Engineering","Space Engineering","","","",""
"uuid:21a284df-7ada-4e3c-9ff2-2d73cc04f534","http://resolver.tudelft.nl/uuid:21a284df-7ada-4e3c-9ff2-2d73cc04f534","Design, Identification and Implementation of a High-Fidelity Cessna Citation II Flight Simulation Model","van den Hoek, M.A.","Pool, D.M. (mentor); de Visser, C.C. (mentor)","2016","As a result of new aviation legislation, from 2019 on all air-carrier pilots are obliged to go through flight simulator-based stall recovery training. For this reason the Control and Simulation division at Delft University of Technology has set up a task force to develop a new methodology for high-fidelity aircraft stall behavior modeling and simulation. As part of this research endeavor, the development of a new high-fidelity Cessna Citation II simulation model, valid throughout the normal, pre-stall flight envelope, is presented. The new simulation model will replace the current baseline model, which is based on the Cessna Citation I, for an increased fidelity and representation of the dynamics of the current laboratory aircraft, the Cessna Citation II. Aerodynamic model identification was done by employing the Two-Step Method. New in this approach is the use of the Unscented Kalman Filter for an improved accuracy and robustness of the state estimates. For the first time, an explicit model structure is presented for the Citation II. Model structure selection by an orthogonal regression scheme has indicated that most of the six non-dimensional forces and moments can be parametrized sufficiently by a linear model structure. It was shown that only the models for the forces in the X and Y body axis would benefit from the addition of higher order terms relating to the aerodynamic angles. On balance, the models for the non-dimensional forces were improved marginally in comparison to the existing simulation model. More significant improvements were made to the non-dimensional moment models.","aerodynamic model identification; flight data model; Cessna Citation","en","master thesis","","","","","","","","2021-08-18","Aerospace Engineering","Control and Operations","","Control and Simulation","",""
"uuid:1eeaf2e5-8ab3-4c61-9bba-6a853d153661","http://resolver.tudelft.nl/uuid:1eeaf2e5-8ab3-4c61-9bba-6a853d153661","Modeling and Parameter Identification of Carbon Black-Filled Natural Rubber for Crash Simulations","Schubert, C.A.","van Campen, J.M.J.F. (mentor)","2017","","","en","master thesis","","","","","","","","2022-05-18","Aerospace Engineering","Aerospace Structures & Computational Mechanics","","","",""
"uuid:2a64dd6e-2110-4c9e-8404-632054a33db9","http://resolver.tudelft.nl/uuid:2a64dd6e-2110-4c9e-8404-632054a33db9","Simulated Shadowgraphy of Transonic Wing-Bound Shock Waves","Onnink, T.S.","Schrijer, F.F.J. (mentor)","2016","","","en","master thesis","","","","","","","","2018-09-01","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:404fa8b9-9d4e-44cc-bf3d-2920f9c6ea1c","http://resolver.tudelft.nl/uuid:404fa8b9-9d4e-44cc-bf3d-2920f9c6ea1c","Crystal plasticity finite element simulations of statistical effects in fatigue life of a Ni-based superalloy","Santos Güemes, R.","Turteltaub, S.R. (mentor)","2016","","","en","master thesis","","","","","","","","2021-06-30","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:4cb0dc14-0ca0-4296-be74-51d0fd752fc5","http://resolver.tudelft.nl/uuid:4cb0dc14-0ca0-4296-be74-51d0fd752fc5","Comparing and improving steering forces in a race car and race simulator to increase simulator fidelity","Advocaat, R.","Voskuijl, M. (mentor)","2015","As circuit testing days are expensive and limited by regulations, racing teams are more and more dependent on simulation tools. Van Amersfoort Racing built their own racing simulator to train drivers in an fully controlled environment. This environment is based on commercially available simulation software rFactor. However, no research on the accuracy of the physics of this software is available. Since level of fidelity of race simulators is important for the perception of racing drivers, force feedback steering forces are analyzed. Information of the real Formula 3 car is used to upgrade the vehicle model used in rFactor and to develop a Multibody Dynamic vehicle model of the same car. Steering metrics are used to make qualitative comparisons between steering force measurement in the real car, the simulator and the Multibody Dynamic model. It is shown that the baseline simulator vehicle model is less sensitive to steering input compared to the real car. Furthermore the simulator driver theoretically senses higher steering torques for a given lateral acceleration discarding electric power limitations of the force feedback motor. As a desire to improve simulator fidelity, a Pacejka tyre model of the Hankook Formula 3 tyre is converted to an rFactor model together with an improved suspension model using the exact suspension geometry as provided by car manufacturer Dallara. Simultaneously, the Multibody Dynamic vehicle model is constructed from these submodels, which purely focusses on lateral dynamics. In order to use the lateral based Multibody Dynamic model as a tool for simulation and assessment, its response is tested given the same input as the real Formula 3 car experienced during a particular test. Three cases are considered: weaving on a straight, a low speed corner and a high speed corner. Longitudinal load transfer is inherent in low speed corners, which, due to its limitation in the Multibody Dynamic model, leaves the model adjustments inconclusive. Furthermore, tyre relaxation plays an important role in low speed corners following each other up in a short period of time, which affect low speed steering metrics. The Multibody Dynamic model showed close correlation of steering metrics with real car measurements for the high speed corner. The updated rFactor model improved steering torque feedback despite higher required steering angles.","Formula 3; Multibody dynamic model; Pacejka tyre model; Suspension geometry; Simulator","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance & Propulsion","","","",""
"uuid:2b0d6c8e-f277-4250-a050-4b5cfa725485","http://resolver.tudelft.nl/uuid:2b0d6c8e-f277-4250-a050-4b5cfa725485","The effect of humidity and strain on the electrical resistance of an epoxy based nanocomposite: An experimental and numerical investigation","Stottelaar, R.A.","Martinez, M.J. (mentor); Ashrafi, B. (mentor)","2015","Recent advances in nanocomposites based on conductive carbon nanotubes (CNTs) have led to investigations of using CNT networks as strain sensors. When CNTs are incorporated into a polymer matrix to form electrical networks, the developed conductive nanocomposite becomes sensitive to strain, thus a linear correlation can be found between strain change and electrical conductivity change (i.e., piezoresitivity). To produce reliable nanocomposite sensors, environmental effects, such as humidity, have to be considered. Humidity is one of the most significant environmental factors, because it is present in most environments. Furthermore, polymers and especially epoxies are known to absorb moisture, which affects the electrical conductivity of developed nanocomposites. Humidity therefore can have a larger effect compared to strain on the electrical conductivity, reducing the reliability of the strain sensor. The present study focuses on the understanding on the effect of the humidity and strain on electrical conductivity of CNT-modified epoxy. Experiments were performed and a mathematical model in Matlab was developed to predict these effects. When compared, a conclusion can be drawn about the usefulness of CNT-modified epoxy as humidity sensors or as a strain sensor outside a controlled environment. An aerospace-grade epoxy (EPON 828) and Multi-walled CNTs (MWCNTs) were used for the fabrication of nanocomposites. Experiments involved measuring current while nanocomposites specimens containing different amounts of MWCNTs were exposed to humidity. Similarly, nanocomposites with the same weight percentages of CNTs were subjected to strain while electrical conductivity was monitored. Results suggested that a 2nd order polynomial relationship between humidity and resistance existed, and a linear relationship between strain and resistance. A comparison between experiments and modelling suggest a good agreement as the magnitude of change in conductivity was in the same order of magnitude. Also, a comparison between the results of the humidity and strain suggest that the resistance increase of the nanocomposite due to humidity was four times higher than the resistance increase due to strain. If designed properly, the sensitivity of the electrical resistance of the nanocomposites developed in this study can be used for humidity sensing applications. However, the application of such nanocomposites for strain sensors is limited to the cases in which the correction to humidity change is applied to the sensor.","CNT; epoxy; humidity; strain; experimental; numerical; Matlab","en","master thesis","","","","","","","","2015-07-23","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","Structural Integrity","",""
"uuid:5ab4fb9b-dcf4-4b1a-9379-c7edf113d26f","http://resolver.tudelft.nl/uuid:5ab4fb9b-dcf4-4b1a-9379-c7edf113d26f","Systems and Knowledge Engineering Design of an Urban Vertical Axis Wind Turbine","Kotsarinis, C.","van Bussel, G.J.W. (mentor); Simao Ferreira, C.J. (mentor); Bierbooms, W.A.A.M. (mentor); Chiciudean, T. (mentor)","2009","The development of wind energy in the built environment is nowadays a growing industry, with several small companies developing different wind turbine designs. However, most of the designs introduced so far were proven to be unsuitable because of the complex urban wind conditions and because of the fact that the design of urban wind turbines is by its nature a challenging process, with many different issues needed to be taken into consideration. The thesis deals with the conceptual design of an Urban Vertical Axis Wind Turbine, with main purpose to improve the state-of-the-art of the design of these systems using Systems Engineering and Knowledge Engineering. A distinct and integrated design procedure has been established. Based on this procedure, the most relevant issues for the design were investigated, including the operational environment. The requirements of the system were derived and the SE process was used for transforming these requirements into optimum design solutions. The resulting topology was analyzed, the components and the interactions between them and the operational environment were identified, together with the design considerations. The necessary scientific knowledge for the design of these systems was identified and allocated to the different components. The application of the methodology focused on the rotor. Additional SE tools were used and the detailed design procedure for the system and for the rotor was addressed. The procedure was supported by Knowledge Engineering/Knowledge Management techniques, and the software tool PCPACK was used for capturing and structuring all the knowledge required for this project. As a result, an initiation of a knowledgebase for the urban VAWT systems has been established.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","Sustainable Energy Technology","",""
"uuid:034abaf9-6247-4a7a-994d-a5be6222d873","http://resolver.tudelft.nl/uuid:034abaf9-6247-4a7a-994d-a5be6222d873","Development of a knowledge-enabled tool repository to support automated generation of multidisciplinary design optimization workflows","Makus, A.","Van Gent, I. (mentor)","2017","","MDO; Multidisciplinary Design Optimization","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:37ee82df-d533-41fb-b6b8-a803c939cc4f","http://resolver.tudelft.nl/uuid:37ee82df-d533-41fb-b6b8-a803c939cc4f","Remote Sensing for Spatial Electrostatic Characterization using the Multi-Sphere Method","Engwerda, H.J.A.","Sundaramoorthy, P.P. (mentor)","2017","Focusing on the rapidly increasing debris population around Earth as well as the scientific and corporate interest in Asteroids, multiple missions for interaction with non-cooperative bodies have been proposed over the last years. Applications such as the Electrostatic Tractor (ET) aiming to reduce the debris populations and missions introducing close proximity or even berthing with bodies in space all require knowledge about the electrostatic characteristics of the target. In order to infer this information in a real-time manner, the Remote Sensing for Electrostatic Characterization (RSEC) method can be applied. By measuring the ambient potential with probes extended from a dedicated spacecraft, an optimization can be performed as to find a best-fit Multi-Sphere Method (MSM) model. onsisting of a set of spheres with a point charge in their middle, this model approximates both the charge and potential of the rotating target. Comparing the in-situ measured potential with the potential obtained from the MSM model, the accuracy of the MSM model can be found and with it the model can be optimized. This thesis provides an extension of the RSEC method to three-dimensional space allowing for multi-axis tumbling motions of the target. Furthermore, simplifications of the model allowing for greater computational speed and simpler application are discussed. In order to validate the model, a Finite Element Analysis (FEA) is performed allowing the RSEC method to be tested for a representative missions scenario where the ET is applied. Based on the results of the FEA simulation, a Surface-MSM (SMSM) is constructed, allowing for multi-axis rotations of the debris, where this would be too computationally expensive with a FEA. The accuracy of force prediction within the ET method is assessed for a representative debris model. Furthermore, insights are offered in the effect of varying model parameters, and the influence of force mis-prediction on reorbiting time and fuel cost is evaluated.","electrostatic; space debris; sensing","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","Space Flight","",""
"uuid:dcae48f1-26f2-4377-891d-77d3eea9bad0","http://resolver.tudelft.nl/uuid:dcae48f1-26f2-4377-891d-77d3eea9bad0","An innovative approach towards solving the problem of trailing edge buckling of large wind turbine rotor blades","Zoethout, J.","Abdalla, M.M. (mentor)","2015","As a result of the increasing mass of rotor blades for large wind turbines, trailing edge buckling is recognized to become one of the critical design drivers. This research project was initiated to investigate a new trailing edge design concept, which is supposed to have a higher buckling capacity, while maintaining its structural performance, and without increasing the total mass. An investigation of a typical blade section from a reference blade revealed the most important parameters that drive the structural design of a blade section. These parameters were applied in analytical models to determine a range of blade sections according to the new technology with the same structural performance. Then linear eigenvalue buckling analysis is applied on finite element models (FEM) to identify the buckling capacity for a selected range of blade sections. Two prototype designs following the new technology are finally presented, one primarily using carbon fibre laminates in the new trailing edge, the other mostly using glass fibre laminates. These prototype designs both show a significant improvement in buckling capacity, and will no longer show trailing edge buckling under the extreme edgewise moments defined for the reference blade. A significant mass reduction is also obtained for both prototype blade sections: a reduction of 8% for the glass fibre concept and even 13.5% for the carbon fibre concept. Significant research is still required for further development of this trailing edge technology, but the current research already provides valuable information on the phenomenon of trailing edge buckling and presents an effective method to design against this buckling mode.","trailing edge; buckling; wind energy; rotor blades; wind turbine","en","master thesis","","","","","","","","2020-01-31","Aerospace Engineering","Wind Energy / Aerospace Structures & Materials","","","",""
"uuid:d0a1bf35-60f7-4846-bf61-a00642df7ed8","http://resolver.tudelft.nl/uuid:d0a1bf35-60f7-4846-bf61-a00642df7ed8","Validating Airline Performance in the Future: Investigation of a Novel Validation Model for Airline Businesses","Jacobs, N.A.A.","Curran, R. (mentor); Beelaerts van Blokland, W.W.A. (mentor)","2015","Over the last decades, air traffic facilitates the movement of people and goods all over the world, enabling economic growth and development. Despite the impact air traffic has on industries and systems all over the world, the aviation industry is influenced by the same factors as well. Energy prices, the economic situation, population growth and other aspects do impact airline businesses, as the most recent economic downturn illustrates perfectly. The world we live in over a couple of decades may vary in many aspects and it is impos- sible to predict all the factors, decisions and actions that will shape it in the future. The understanding of world as one global system, its dependencies and dynamics can never be perfect, and is limited by our knowledge. Now and in the future. Despite the ability to make perfect forecasts how the world will look like in the future, scenarios can help to define how factors will act so a variety of future pathways can be explored. In order to help airline businesses and organisation, such as the IATA, formulating and validating strategies, this work focuses on the development of a framework that enables the forma- tion and validation of scenarios that are based on dynamics, dependencies and relations of the global system. Based on a system dynamics approach, a Integrated Assessment Model is developed based on proven concepts of socio-economic and climatological modelling. This model will form the basis for the other models that will be added to calculate the demand for passenger kilometers, irrespective of the transport mode. Based on pricing and time expenditures of a journey by a transport mode, a distribution of passenger kilometers per transport mode is calculated. An Air Transport Model is used to mimic airline operations based on three types of aircraft. In this model, the transport demand, expressed in RPKs, is used to drive the demand for flights. Depending on the utilisation capacity ratio, an airline is able to cope with the demand. Above capacity utilisation ratios, the airline has to delay flights or order new assets (aircraft or runways) in order to accommodate the transport demand. Under some situations, this might leed to higher airfares or higher time expenditures per flight, which affect the balance of transport kilometers in respect to the other transport mode. Based on the performed amount of flights and RPKs, the Air Transport Model calculated essential KPIs, which are used to express the performance of the airline businesses. A Value Operations Methodology is used to validate the performance for both economic and non-economic aspects of an airline. By this methodology, several aircraft options and airline strategies can be validated under different socio-economic scenarios. Eventually helping airlines to improve their short-term as well as long-term strategical decisions.","airline; performance; KPI; transport; system dynamics; validation; holistic; operations","en","master thesis","","","","","","","","2015-04-13","Aerospace Engineering","Air Transport Operations","","","",""
"uuid:e2178fc3-87e7-47e6-b42f-3e184f4de6d4","http://resolver.tudelft.nl/uuid:e2178fc3-87e7-47e6-b42f-3e184f4de6d4","Characterisation of High Temperature Stable In-Situ Joints for Grid Cores in C/C-SiC Sandwich Structures","Shirke, R.V.","Zarouchas, D. (mentor)","2017","","","en","master thesis","","","","","","","","2022-02-23","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:193f8b1e-ea0c-4a6c-afa4-f49c14ba80e6","http://resolver.tudelft.nl/uuid:193f8b1e-ea0c-4a6c-afa4-f49c14ba80e6","A Medium-Fidelity Method for Rapid Maximum Lift Estimation","Singh, B.","Vos, R. (mentor)","2017","A medium fidelity tool has been developed for the computation of a wing's maximum lift coefficient in low speed while adhering to conceptual aircraft details. This tool is part of the Initiator which is a conceptual/preliminary aircraft design tool developed by the FPP group. The methodology comprises out of a synergy between empirical relationships and low order aerodynamic analysis in terms of potential flow theory. The tool's empiricism originates from Datcom's semi-empirical Critical Section Method (CSM) and the Pressure Difference Rule (PDR). To complement deficiencies, routines have been implemented regarding induced angle of attack, flap lift effectiveness, chord extension, and multi-element lift curve slope. For rapid convergence, the Newton-Rapson root finding method is coupled with a Kreisselmeier- Steinhauser function to efficiently find the critical stalling conditions which are defined within both the CSM and PDR. The proposed tool is validated against several experimental test cases: A Fokker F27 straight wing model in clean configuration; two 45 degrees swept-back reference wings in clean configuration; and two Royal Aircraft Establishment (RAE)’s 28 degrees swept-back wing having a variable span deployed single-slotted Fowler flap. The validation demonstrated that the maximum lift coefficient could be predicted within a 11% error margin while requiring a computational expense of mere seconds. Erroneous stall angle results were found on swept-back wings due to the negligence of spanwise boundary layer flow effects on wing stall. Configurations with high flap deflection angles showed deficiencies due to the inability to account for the combined viscous effects which prevail in high-lift flow within a conceptual approach.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Flight Performance and Propulsion","",""
"uuid:a70b25ef-f780-41f7-afa0-9fb3f5e8e992","http://resolver.tudelft.nl/uuid:a70b25ef-f780-41f7-afa0-9fb3f5e8e992","The Effects of Pylon Blowing on Pusher Propeller Performance and Noise Emissions","Sinnige, T.","Veldhuis, L.L.M. (mentor)","2013","Growing concerns about the environmental impact of aircraft operations and increasing fuel prices have led to the demand for more fuel-efficient aircraft. One of the technologies with the potential to offer a significant reduction in fuel burn is the open rotor engine. However, the noise emissions of such engines are higher than for turbofans, partially due to the typical installation of the open rotor in a pusher configuration. The wake shed by the upstream pylon results in a velocity deficit at the propeller disk, leading to unsteady blade loads and additional noise emissions. This thesis investigated the potential of pylon trailing edge blowing to reduce the adverse effects of airframe installation on the performance and noise emissions of pusher propellers. Experimental and numerical analyses were performed, focusing on the pylon wake profiles, the propeller performance, and the propeller noise emissions. The experiments were executed in Delft University of Technology's Open Jet Facility using a scale model pylon and a single-rotating powered propeller model. The numerical analysis combined an existing propeller lifting line code with analytic methods suited to predict the effects of installation on the propeller performance and noise emissions. Pylon wake measurements showed that application of the pylon trailing edge blowing system resulted in reductions in the integral wake velocity deficit of up to 60% when compared to the unblown configuration. However, no full mixing of the external flow and the flow blown into the pylon wake was obtained. As a result, the application of blowing did not completely eliminate the pylon wake, but instead led to a velocity overshoot in the wake center and two local minima left and right of the wake centerline. From the studies of the propeller performance it was concluded that the effects of installation on the time-averaged performance are small, with maximum differences between the isolated (without pylon) and installed (with pylon) thrust and torque of less than 2% for advance ratios below 1.4. For the same advance ratio range the peak-to-peak variations in the installed thrust and torque were computed to be smaller than 4% of the mean value. Excellent agreement was obtained between the experimental and numerical time-averaged isolated propeller performance for advance ratios above 0.7, with a maximum difference of 1% between the computed and measured data. The measurements of the propeller noise emissions showed that the sound pressure level (SPL) of the propeller tones is strongly increased due to the installation effects, with noise penalties of up to 10 to 25 dB for the first six tones occurring at integer multiples of the blade passage frequency (BPF). Broadband levels on the other hand were unaffected by the presence of the upstream pylon. The application of blowing resulted in significant noise reductions when compared to the unblown installed case. Depending on the operating conditions, at the highest blowing rate considered SPL reductions were obtained of up to 4 dB for the 1BPF tone, 8 dB for the 2BPF tone, and 12 dB for the 3BPF tone. Furthermore, the higher BPF tones (4BPF and above) were practically eliminated. The evolution of the noise reduction due to blowing as a function of the advance ratio followed the trend in the noise penalty due to installation, thereby confirming that the application of blowing indeed successfully opposes the installation effects.","propeller; propeller noise; pylon blowing; aeroacoustics","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","Aerodynamics","",""
"uuid:7572bbcd-21bf-4655-937e-43bc179f2854","http://resolver.tudelft.nl/uuid:7572bbcd-21bf-4655-937e-43bc179f2854","Physical-based Loss Models for Organic Rankine Cycle Turbines","Raj, P.","Pini, M. (mentor)","2016","","","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:7ab39a28-2902-4811-8efc-c4645d656e74","http://resolver.tudelft.nl/uuid:7ab39a28-2902-4811-8efc-c4645d656e74","Identification and analysis of point scatterers in time series InSAR","Van der Torren, P.T.","Hanssen, R.F. (mentor); Esfahany, S.S. (mentor)","2011","In this study methods are developed for improved analysis and processing of PSI data. PSI, or radar interferometry, makes it possible to use satellite radar images to measure deformation of the Earth’s surface and objects on it with millimetre accuracy. However, interpretation of the measurements and identifying the actually measured objects is still a common problem. There are no dedicated tools available for validation, for finding both falsely detected and falsely rejected points, or for deeper analysis of PSI results. Existing algorithms for automatic coherent scatterer selection need a lot of acquisitions to obtain reliable results, which makes it necessary to collect data for many months or years before processing can be done. In this study a suite of tools is developed that facilitate detailed analysis of results and versatile processing of radar data. This suite consists of a visual inspection tool, and a toolbox that handles metadata and can do versatile processing of radar data. Furthermore a method is developed for reliable point scatterer selection, that works for a small number of acquisitions, among other improvements.","satellite; remote sensing; subsidence; deformation; InSAR; radar interferometry; software; scatterer; signal processing; time series; Delft train tunnel","en","master thesis","","","","","","","","","Aerospace Engineering","Mathematical Geodesy and Positioning","","Geomatics","",""
"uuid:ab02439b-749b-400d-b113-adaf49e00134","http://resolver.tudelft.nl/uuid:ab02439b-749b-400d-b113-adaf49e00134","Floating LiDAR Technology: Oceanographic parameters influencing accuracy of wind vector reconstruction","Cool, G.A.","Bierbooms, W.A.A.M. (mentor)","2016","Wind assessment of new locations prior to the installation of wind turbines is an established process. However, this process is still very costly. The common way to measure offshore wind profiles is the usage of met masts, which get more expensive with increasing water depth and hub height. Recently, wind measurement LiDARs are installed on floating platforms to investigate the wind profile offshore. Floating LiDARs are a promising technology thanks to low cost and high flexibility. However, further understanding is required in order to make floating LiDAR technology fully acceptable. The movement of a floating LiDAR brings some uncertainty in reconstructing the wind vector and turbulence characteristics. These uncertainties hold back the full commercial acceptance of LiDAR technology in the offshore wind energy industry. In order to accept floating LiDARs as a valid technology, acceptance criteria need to be defined in terms of accuracy and confidence of the results. This thesis has developed a simulation tool to define and model the effect of uncertainties in floating Li- DAR technology, which influence the accuracy of the wind field characterisation. The model reconstructs wind vectors as seen by a specified LiDAR and is capable of analyzing the parameters influencing wind vector reconstruction. These parameters can be categorized in wave, wind and LiDAR conditions. Several wind profiles were used as input: a logarithmic wind profile for a first assessment, synthetic turbulent wind fields and Large Eddy simulations (LES) for a more realistic approach. Wave conditions based on the Airy wave and real-motion data are used to see the influence of wave height, wave period and wave number. It has been observed that floating LiDARs can reconstruct 10min velocities in a very accurate way, regardless of the experienced wave conditions which varied from normal to extreme conditions. For all considered wind tools, the error was less than 0.1 m/s for the averaged 10min wind speed, with a very small standard deviation, ¾. Reconstructing turbulence characteristics has been proven to be less accurate. The error is significant and cannot be ignored. With a reference turbulence intensity value of 8% at an altitude of 100m, the average bias can go up to 0.60% with a ¾-value of 0.52%for synthetic wind fields. In more extreme wave conditions, the average bias can go up to 1 % andmore. An error of more than 3%may occur at altitudes of 150m or higher for the turbulence intensity when using LES files in these extreme conditions. The use of motion correction is suggested to reduce this bias. This correction can happen with a mechanical system (motion stabilization platform) or a correction algorithm built into the software. Since the approach that was used in this research has proven to be successful, further research can be performed based on this study. Further investigation should be focused on understanding turbulence behaviour, measured by floating LiDARS. Also the usage of wind data coming from measurement campaigns should be valuable to proceed with in this research.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Wind Energy","",""
"uuid:94039d45-565e-4d6f-aee5-819fc1b3e2a6","http://resolver.tudelft.nl/uuid:94039d45-565e-4d6f-aee5-819fc1b3e2a6","Inclusion of noise-related constraints in departure procedure optimization","Haagen, J.W.M.J.","Hartjes, S. (mentor); Visser, H.G. (mentor)","2015","The ever-increasing use of aircraft, together with the on-going urbanization causes increasing noise nuisance due to aviation. This is attenuated by the positioning of airports close to densely populated areas. For this reason the majority of the large airports in the world indicate that noise is one of the limiting factors in the expansion of the airport. One solution of adjusting operational procedures is the adjustment of near-airport operations of aircraft. Previous research shows the application of multi-event optimizations which optimize the lateral aircraft tracks for multiple aircraft simultaneously. Although the results of these optimizations proved significant improvements in terms of community noise, still two problems remain open-ended, which prohibit (or limit) the practical implementation of the results. - The multiple aircraft departures, which currently often show dispersed flight tracks, are being concentrated onto one track. This concentration of flights onto one track allows a reduction in community noise but causes peak loads in noise at the same time. The increased technical capabilities allow aircraft to accurately follow predetermined tracks which causes problems equal to the described problem in the near future. - By repositioning aircraft tracks (and the resulting noise) the total amount of noise nuisance decreases. At the same time an increase in noise received at some locations due to the creation of new noise (noise that is new for a location). The new noise has proven to cause significant resistance to the implementation of new aircraft tracks. This thesis questions the desirability of solely focussing on the reduction of one specific community noise metric, of which the amount of people highly annoyed and awakenings have been used in the past. Instead this research aims to find to which extent peak noise loads and new noise can be taken into account in the optimization of aircraft tracks. For this purpose, two noise impact criteria have been integrated. To be able to investigate the desirability of either concentrating or dispersing aircraft tracks a multi-event optimization is implemented that allows to optimize two aircraft (Boeing 737-300 and Boeing 747-400) tracks simultaneously, for the lateral tracks as well as. Constraints with respect to noise nuisance are implemented within the optimization tool. This novelty converts the optimization problem from finding the optimum combination of fuel and community noise to finding a minimum cost function value while assuring a pre-defined level of community noise. This in turn allows to include new types of noise metrics in the cost function of the optimization.","optimal control; noise abatement; community noise impact; aircraft; departure","en","master thesis","","","","","","","","","Aerospace Engineering","Air Transport and Operations","","Traffic Management and Airports","","52.30907, 4.76338499"
"uuid:769c6ff8-cc10-4fee-b6a7-b31af48f8434","http://resolver.tudelft.nl/uuid:769c6ff8-cc10-4fee-b6a7-b31af48f8434","CFD based aerodynamic redesign of a Marcos LM600","el Ouazizi, A.","Boermans, L.L.M. (mentor)","2006","The final years of the 1960s mark the introduction of aerodynamics to the field of motorsport and they have grown to be inextricably connected ever since. The competing cars in nearly every motorsport category are fitted with aerodynamic devices while Formula One teams actually have departments that are primarily concerned with the aerodynamic design of their vehicles. The GT-class is another motorsport category that hosts cars that are predominantly shaped with the aim to optimize aerodynamic efficiency. The Marcos LM600 is one of the cars that competes in the GT-class and forms the sculpture of this thesis. The subject of this thesis is to enhance the aerodynamic characteristics of the Marcos LM600 through utilization of Computational Fluid Dynamics (CFD). This implies that on going through this report a number of modifications to the Marcos LM600 will be presented with the aim of obtaining an aerodynamically improved racing car. In a sense the Marcos LM600 thus resembles a sculpture that assumes its final shape after a succession of modifications. The aerodynamic characteristics that are of primary significance to a racing car are the downforce and drag. The obvious target is to maximize the downforce and downforce-to-drag ratio. Apart from this force ratio, the downforce distribution between the wheel axes is another important racing car characteristic. The actual handling stability of the car is determined by the force balance between the front and rear wheels. Too much ”grip” on the front wheels causes oversteer, while too much rear wheel grip causes understeer. Thus when designing racing cars, the aerodynamicist should take into account the front wheel and rear wheel downforce and to obtain either a vehicle with neutral steer or slightly oversteer1. However, vehicle handling is beyond the scope of this thesis, which is why the Marcos LM600 will only be optimized in terms of downforce and drag, leaving out their effect on the vehicle stability.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e5f509a2-755b-4ba9-b8bb-30b1ba2cbea8","http://resolver.tudelft.nl/uuid:e5f509a2-755b-4ba9-b8bb-30b1ba2cbea8","Increasing Task-Sharing Performance by Haptically Assisting a Tunnel-in-the-Sky Approach","Beeftink, D.G.","Borst, C. (mentor); Van Paassen, M.M. (mentor); Mulder, M. (mentor)","2017","To investigate the effects of haptic feedback on the task-sharing performance during approach when using a Tunnel-in- the-Sky display, a within-subject simulated experiment with 12 participants was conducted in the SIMONA Research Simulator at Delft University of Technology. The experiment consisted of a primary Tunnel-in-the-Sky tracking task, where the pilots had to fly with one non-haptic and two haptic settings. Primary task performance was measured by means of position errors and roll and pitch rates. A secondary task was presented to the pilots as bucket shaped figures superimposed on the outside visuals, where the participants had to indicate the direction of the divergent figure. Secondary task performance was measured by success rate, average time to answer correctly and - by means of eye-tracker measurements - head-up time and number of gaze switches. Next to these objective measures pilots provided a subjective measure of their mental effort after each run. Lastly, the haptic and human induced forces were recorded, to be able to measure whether the pilot was fighting or cooperating with the haptic feedback provided. Results of the experiment show that haptic feedback can significantly increase task-sharing performance of the pilot, especially for a challenging primary task, but that too dominant haptic feedback can introduce a risk of over-reliance.","experiment; haptics; haptic; guidance; task-sharing; human-machine","en","master thesis","","","","","","","","2018-03-01","Aerospace Engineering","Control & Operations","","","",""
"uuid:e8e291ce-e6c1-41a1-83dc-826caf779f79","http://resolver.tudelft.nl/uuid:e8e291ce-e6c1-41a1-83dc-826caf779f79","Stability of a Chinook helicopter with multiple underslung loads","Thijs, R.J.","Pavel, M.D. (mentor)","2016","This thesis describes the process of creating numerical derived stability analysis of an Chinook with underslung loads. A helicopter model with underslung loads is build and numerically linearized. After the linearization the eigenvalues are calculated and plotted. It was found that numerical linearization works well with a single solid body, but becomes troublesome when multiple bodies are present.","","en","master thesis","","","","","","","","","Aerospace Engineering","ASDM","","System Engineering and Aircraft Design","",""
"uuid:fcd6522c-9139-48f6-be1b-55b509b588c1","http://resolver.tudelft.nl/uuid:fcd6522c-9139-48f6-be1b-55b509b588c1","Predicting the icing risk of wind turbine rotor blades using aircraft icing tools","Spranger, L.L.C.C.","Timmer, W.A. (mentor); Sørensen, J.N. (mentor); Stoevesandt, B. (mentor); Strickmann, G. (mentor)","2016","As on-shore wind farms are being installed in colder and harsher climatic areas in increasing numbers, it becomes more and more important to have adequate measures for dealing with rotor blade icing. Rotor blade icing can lead to a number of serious consequences for the safety, power production, and operation of a wind turbine or entire wind farm. As part of a research project on wind turbine icing carried out by the German government, a method to estimate the icing risk for a wind turbine rotor at an early stage has been developed and programmed in Python for the wind turbine manufacturer Enercon. This ‘Kalkulativer Icing Risk Analyser’, in short ‘KIRA’, uses discretised wind turbine blade geometry and meteorological icing parameters as input to determine the icing risk of the rotor by using a critical icing rate limit that is characteristic to a certain wind turbine type. The method for determining this icing rate limit has been employed on the Enercon E-82 2MW wind turbine using a power curve comparison strategy.","Windenergy","en","master thesis","","","","","","","","2021-06-27","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","EWEM European Wind Energy Master","",""
"uuid:1ec58044-5e49-447e-b956-223d1807fd75","http://resolver.tudelft.nl/uuid:1ec58044-5e49-447e-b956-223d1807fd75","Update Offshore Wind Atlas: Implementing a variable sea surface roughness","Donkers, J..A.J.","Bijl, H. (mentor); Brand, A.J. (mentor)","","In 2005 the Energy research Centre of the Netherlands (ECN) published its first version of the Offshore Wind Atlas of the Dutch part of the North Sea [3]. This version has been updated and improved using longer time series and another approach for the calculation of the roughness of the sea surface. In contradiction to other Wind Atlases which are based on measurements [28], use is made of data from the Numerical Weather Prediction model Hirlam. Measurements of wind speeds and directions are only used to validate the Wind Atlas. For the Offshore Wind Atlas, the Hirlam data is interpolated where for the vertically interpolation use is made of the Businger-Dyer profiles in combination with the Monin-Obukhov length [3]. One of the required parameters for the interpolation is the surface roughness. For land, it can be assumed constant while for sea it is variable. In the previous version of the Offshore Wind Atlas, the sea surface roughness has been determined using Charnock’s relation [9], where the so-called Charnock parameter is constant. In the new version, the equation of Hsu is introduced which states that the Charnock parameter is variable and dependent on the wave steepness i.e. the wave height divided by the wave length [19]. Assuming that the North Sea is a shallow sea and using the general wave equation, which relates the sea depth and wave length to the phase velocity of the waves, it was found that the wave steepness can be rewritten in a fraction of the wave height over the wave period multiplied by the square root of the sea depth times the gravitational acceleration. These quantities are derived from measured values which are interpolated to the location of interest. Using this approach, it is tried to improve the prediction of the wind speed distributions for a given location and altitude. Using wind measurements at several locations it was found that adding the wave data to the computations show a small improvement in the estimation of the wind speed distribution compared to the previous version of the Offshore Wind Atlas. For each measurement location and method, a two parameter Weibull distribution has been made, after which a comparison was done between the various shape and scale parameters. Generally, the scale parameter was overestimated by both versions of the Offshore Wind Atlas compared to the measurements. The cause of this behavior might be found in the data used to make the Atlas. The shape parameter is well predicted by the new version of the Offshore Wind Atlas due to the use of wave data. The influence of the wave data is found to be larger for lower altitudes than for higher altitudes. Besides Weibull distributions, also maps with average wind speeds are given by the Offshore Wind Atlas which are compared to older maps","Sea Surface Roughness; Wind Atlas; North Sea; Offshore","en","master thesis","","","","","","","","2010-11-17","Aerospace Engineering","","","","",""
"uuid:a33fd86f-c4df-4286-824c-6e92d68a2cba","http://resolver.tudelft.nl/uuid:a33fd86f-c4df-4286-824c-6e92d68a2cba","The assessment of dynamic wake effects on loading: Dynamic wake modeling and comparison of methods for wake loading assessment","Han, T.","Bierbooms, W.A.A.M. (mentor); van Bussel, G.J.W. (mentor)","2011","The wake effect from upstream wind turbines is a hot topic recently and many researches on wake modeling have been carried out in the past few years. The wake models have evolved from the simple semi-empirical approach to the dynamic meandering model using the Computational Fluid Dynamics (CFD) codes. However, some of current wake models cannot simulate the dynamic wake meandering process while the other CFD models are too complicated for engineering applications. So the purpose of this thesis is to develop a simple numerical wake model including the detailed wake velocity deficits and dynamic wake meandering process in the atmospheric boundary layer. The Simplified Eddy Viscosity (SEV) model is developed based on the simplified Navier-Stokes equation in Ainslie's work. It describes the wake mixing process in the atmosphere and gives an estimation of quasi-steady two dimensional velocity deficits. Furthermore, the turbulence generator is implemented in the SEV model and provides a three-dimensional turbulence flow field in the wake. An experimental validation study of stationary wake deficits is carried out by using measurements from ECN‘s wind turbine test station. Moreover, the SEV model is modified according to ECN‘s measurements and it shows a fair agreement with GH Bladed eddy viscosity model. Besides the stationary wake deficits, a simple dynamic wake meandering mechanism is introduced in this thesis. According to this mechanism, the Dynamic Wake Meandering (DWM) model is developed, which is an integration of the wake meandering process, the wake deficits from the SEV model, and the aeroelastic model from GH Bladed. The DWM model is validated with Risoe‘s model and GH Bladed and there is good agreement between these models. The DWM model is used for load analysis and then compared with the traditional estimation method MET prescribed by the IEC 61400-1 standard. The flow fields in the DWM model are closer to the physical processes of wake transportation in the atmospheric boundary layer. The results show a significant difference between the methods chosen for the fatigue damage estimation.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy Research Group","","","",""
"uuid:821d5aaf-99a8-4fc7-a32d-eadb5d104aa9","http://resolver.tudelft.nl/uuid:821d5aaf-99a8-4fc7-a32d-eadb5d104aa9","Welding of thermoplastic to thermoset composites through a thermoplastic interlayer","Van Moorleghem, R.","Fernandez Villegas, I. (mentor)","2016","Currently the joining of cured thermoset composite materials for aerospace applications occurs in a suboptimal manner. The structure is joined by mechanical fastening, optionally in conjunction with an adhesive. The joining is sub-optimal because the fasteners require holes in the thin fibrous structure. These holes are stress concentrations, therefore the number of plies and thus the weight of the structure is increased to accommodate them. Adhesive joints do not require holes but these joints still have challenges in the field of non-destructive testing (NDT), which precludes their use for the joining of structural parts in aerospace. Consolidated thermoplastic materials have an additional joining technique that can be used, namely fusion bonding. This technique uses the property that distinguishes thermoplastics from thermosets, they have the ability to melt or soften under increased temperature. In this molten or softened state themolecular chains of the thermoplastic resin possesses increased mobility. If the thermoplastic is in intimate contact with another miscible thermoplastic while it is in this heated state the molecular chains can diffuse into each other and intermingle, creating a bond. This bond does not possess the stress concentrations associated with mechanical fastening, or the phenomenon of kissing bonds which inhibits certification in adhesive bonds. In industry fusion bonding is solely applied to unreinforced thermoplastic materials, fusion bonding of thermoplastic composites is only applied in research. To enable fusion bonding of cured thermoset composites a thermoplastic interlayer can be co-cured, which is a thin thermoplastic film that provides a fusible surface to the thermoset structure, it can thus be used to fuse the thermoset structure to another fusible part. The interlayer can be surface treated before cure so that they can form an interfacial adhesive bond with the thermoset laminate. This approach makes the joint susceptible to the same challenges faced by adhesive bonding. Therefore this research investigates the use of a material combination that is initially miscible, so that they can form an interphase during cure instead of an adhesive interface, the interphase is a gradual transition from onematerial to the next . The fusion bonding process itself also poses some challenges. Fusion bonding of aerospace grade thermoplastics typically require temperatures far above the maximum temperature allowed by the co-cured thermoset laminate. A solution to this problem is the use of a fast and concentrated method of heat generation that can keep the elevated temperature experienced by the thermoset material limited and short in time, preventing thermal degradation. Ultrasonic welding is a fusion bonding technique that is capable of creating fusion bonds with heating times in the order of 500ms, proven to be short enough to prevent thermal degradation for the materials used in this research. Another important issue foreseen and addressed in this research is the question if the interphase between the interlayer and the thermoset material can withstand the aggresive welding process. Previous experience with surface treated interlayers showed that some interlayer/ surface treatment/thermoset material combinations can detach at the interlayer/thermoset interface after welding. This research shows that the interphase is affected in some locations, but the fusion bond is nonetheless maintained through the entire weld overlap. The apparent lap shear strength of the joints created with an interphase forming interlayer is comparable to the joints created with adhesive interface forming interlayer. Both joint types retain their strength when exposed to prolonged exposure to moisture, simulating a worstcase scenario in amanufacturing setting. Exposure to a cleaning solvent significantly affected the interphase forming joint type, attributed to the amorphous structure of the thermoplastic used. This research shows that when selecting the right material as interlayer for creating a fusion bonding capable thermoset laminate, a joint can be created that could avoid the certification challenge experienced by adhesive bonding, while simultaneously using aerospace grade materials without thermally degrading the joint during fusion.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Engineering, Materials Engineering","","","",""
"uuid:dc8d1f5a-9f72-472f-a044-91cab61189a1","http://resolver.tudelft.nl/uuid:dc8d1f5a-9f72-472f-a044-91cab61189a1","Haptic Interface for UAV Teleoperation: Changing Haptic Control Device Stiffness based on Environmental Constraints","Kolsteeg, J.M.","Smisek, J. (mentor); Van Paassen, M.M. (mentor); Mulder, M. (mentor)","2014","Unmanned Aerial Vehicle (UAV) teleoperators suffer from a reduced situational awareness, contributing to a high UAV accident rate. The implementation of a haptic interface is a way to provide them with more information about obstacles in the environment in order to compensate for this. Research focused on systems that actively help the teleoperator to avoid collision at a last stage. The haptic interface as described in this paper guides the teleoperator in a more passive way, making him aware of unsafe trajectories in an earlier stage instead of actively trying to avoid collision. This new haptic interface changes the stiffness of the control device based on environmental constraints, leading to a changing non-linear force-displacement relationship for the control device. In order to explore the performance of this haptic interface, off-line simulations and a human-in-theloop experiment have been performed. The results of the off-line simulations showed the potential to prevent collisions at an early stage. However, the results of the human-in-the-loop experiment do not show the expected improvements for the haptic interface, no significant differences can be identified. The cause of this is hypothesized to be both due to a low task difficulty level and the boundaries of the feedback not corresponding to the physical dimensions of the UAV. However, significant differences were identified when comparing the design choices of the haptic interface.","UAV; haptic interface; haptic feedback; stiffness; teleoperation","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Simulation","","Profile II","",""
"uuid:e140aeab-891d-437d-b96d-8a5c1ed9d94a","http://resolver.tudelft.nl/uuid:e140aeab-891d-437d-b96d-8a5c1ed9d94a","Quantitative Assessment of Adhesively-bonded Joints Using Ultrasonic Guided Waves","Verze, M.","Kassapoglou, C. (mentor)","2016","Maintenance is a costly but vital part of an aircraft lifespan. Regulations demand scheduled and rigorous inspection to ensure safety and airworthiness in the long term. Studies estimate that up to a third of the total operational cost of an aircraft is spent in maintenance checks. Consequently, design choices are made to take into account these requirements, which mean that conservative but easy to maintain designs are often preferred. Adhesive bonding is a typical example of a design choice that is overlooked due to the lack of efficient and reliable non-destructive maintenance and inspection. The mechanical advantages of adhesive bonding make it a promising substitute to mechanical joining methods but a consistent lack of confidence in the long term behaviour of these joints is limiting its broad application. Available NDI methodologies are limited both in reliability and versatility, and weak bonds can still go undetected. A guided waves based method has been developed and used to inspect a set of different adhesive interfaces in especially manufactured specimens. The method estimates an equivalent bondline length which can be directly correlated to the residual strength of the inspected bond. The tests showed good correlation even in cases where conventional ultrasonic methods (C-scan) were unable to detect any defects. The proposed method promises to further enhance the detection of weak bonds in bonded joints providing a rapid and accurate evaluation and direct correlation with mechanical strength of inspected bonds.","C. thesis; msc; adhesive; Lamb waves; inspection; guided waves","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","Aerospace Structures & Computational Mechanics","",""
"uuid:be09e1d9-8c49-4d2c-ba77-bc929a360c7c","http://resolver.tudelft.nl/uuid:be09e1d9-8c49-4d2c-ba77-bc929a360c7c","Wake evaluation of a generic wing-flap-jet aircraft model: A PIV and 5 hole probe comparative study","van Kalken, J.","Scarano, F. (mentor)","2008","The wake behind a simplified model of a generic aircraft (the SWIM model) is measured in the Low Speed Low turbulence wind tunnel (LSL) at Delft University of Technology. Two measurement techniques have been used in order to qualitatively and quantitatively measure the wake, i.e. stereoscopic particle image velocimetry (Stereo PIV) and a 5 hole probe (5HP). Furthermore balance measurements have been carried out over a range of configurations for later comparison purposes. The goal of the wake measurements is to give a comparison between the two measurement techniques. The 5HP measurements are processed using a windows based program called Pressure Field Visualisation. This program calculates vector fields from the input pressure data and has several exporting options. The Stereo PIV measurements are correlated using DaVis 7.3 using a window size of 16 x 16 pixels with 50% overlap. The results showed that the Stereo PIV measurements contained more noise than the 5HP measurements. Furthermore, the measured vorticity in and near the vortex centers were lower for the Stereo PIV technique. This is caused by the lower resolution of the Stereo PIV arrangement used in the current research. The jet outflow has been measured with the 5HP and is symmetrical. The data is analysed using Matlab routines, where a program is written to analyse and edit the flow field. The analysis is done by calculating and removing the downwash and removing the influence of each vortex on the other vortex by making a tangential velocity fit. Then a second tangential velocity fit of the clean vortex is created. For the cases where the yaw angle is zero the measurement techniques give comparable tangential velocity fits. The 5HP has a larger damping in the pressure acquisition system creating a wider scatter in the tangential velocity data from the Stereo PIV technique. When the angle of attack is increased for both vortices the core radius stays equal but the maxi- mum tangential velocity increases yielding a higher circulation. By activating a jet the vortices get a larger core radius while a decrease in maximum tangential velocity is found. The spacing used in the wake survey analysis (using WAKE) is of importance for obtaining good results. Different spatial resolutions have been analysed which resulted in a maximum of 3 to 4 mm spacing after which the results diverge. The drag results are mostly influenced by the change in induced drag when the spatial resolution decreases. This indicates that the Stereo PIV data grid should give comparable results to the 5HP out of the wake analysis. The 5HP measurements show good agreement with the balance measurements. The lift coefficient is close to the lift coefficient measured with the balance (with a maximum difference of 5%) while the drag coefficient is slightly lower (around 80% from the balance measurements) due to the drag of the support strut out- side the measured wake. However the calculated lift in the Stereo PIV measurements are lower then those from the 5HP measurements. The spatial resolution of the Stereo PIV arrangement is the cause of this. After increasing the vorticity near the vortices and removing the vorticity outside the wake, the local lift distribution was equal to that of the 5HP. Comparisons with previous studies show that there is an agreement with test data from both the DNW as well as the towing tank. The data obtained by the NLR gives a com- parable lift distribution to the distribution found in this thesis. Their measurements are performed further behind the model (x=b = 1:25). The calculated local lift distribution show that the vortices have moved slightly around each other. The tangential velocity data from the towing tank also show similarities to those in the current research. Both the shape and core radius of the vortices are alike.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:bf30d6f8-4ac3-4cbe-9869-4fe923118e6f","http://resolver.tudelft.nl/uuid:bf30d6f8-4ac3-4cbe-9869-4fe923118e6f","Cross-border Arrival Management to reduce Traffic Bunching at Schiphol Airport","Van Horssen, M.","Hoekstra, J.M. (mentor); Ellerbroek, J. (mentor)","2017","","","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:8da25421-9a0c-4205-8804-38d285c9c6c9","http://resolver.tudelft.nl/uuid:8da25421-9a0c-4205-8804-38d285c9c6c9","A Low Emissions Taxi Movement Planning Tool","Evertse, C.","Visser, H.G. (mentor)","2014","The goal of this research project was to develop and test an online, automated taxi movement planning tool, that optimizes the timed taxiing routes of all aircraft on an airport, by minimizing the impact on the environment. Automatic taxi planning tools have been developed before, but the emissions have never been included before as a factor in the optimal taxi planning. Since the tool is to be used in real-time in an operational context, the daily operations of airports have been analyzed and the tool has been tailor-made to meet the operational requirements. In order to cope with perturbations on the taxiway grid, the tool is capable of optimizing a taxi planning within 15 seconds. This way, a new planning can be calculated quickly if there are perturbations on the taxiway grid. The objective function comprises the following criteria: Minimization of the emissions (normalized and weighted in the objective function) For departures: minimization of the absolute deviation from the departure slot time For arrivals: minimization of the taxiing time (normalized in the objective function) The mixed integer linear programming (MILP) methodology has been used to formulate and solve the problem. The formulation in this research project uses binary routing variables and continuous timing variables. This way, the routing and scheduling problem can be solved without the disadvantages of discrete time. The emissions of nitrogen oxides (NOx), carbon monoxide (CO), unburned hydrocarbons (UHC), carbon dioxide (CO2) and particulate matter (PM) are included in the optimization. The developed optimizer minimizes those five emissions, along with fuel burn, delays for departures and taxiing times for arrivals. The environmental variables are modeled using an action-based model, in which the emissions caused by accelerating, idling during a hold, taxiing at constant speed and turning have been modeled. The developed tool has been subjected to a comprehensive test case. The test case simulated a full day of flights on a major European hub: Amsterdam Airport Schiphol. The output of each emission type increased with only 1 to 2 percent, in comparison to the theoretical optimum (which is a scenario where each flight would be able to travel its optimal, unimpeded route, unhindered by separation constraints). When the emission optimization criteria were switched off (while keeping the objective criteria of arrivals taxiing time and departure slot time deviation), the output of each emission type increased with around 20 to 25 percent, in comparison to emission-enabled optimization. The computational times remained within limits, so the requirement was met of having the ability to do a replanning every 15 seconds. The environmental benefit of using this type of optimizer is estimated to be around 10 to 20 percent per emission type. The reduction can be attributed to the elimination of the buffering and waiting queues in front of runways, the elimination of holds at nodes and the intelligent overall routing, timing, sequencing and scheduling on the taxiway grid. Therefore, this research project proves that a surface movement planning tool, which minimizes the emissions or the total taxiing time, can be valuable for airports that have dense taxiing traffic and stringent environmental requirements.","airport; taxiing; ground surface movement; emission; emissions; optimizer; taxi movement planning tool; movement planning; environment; taxiway; milp; aircraft","en","master thesis","","","","","","","","","Aerospace Engineering","Air Transport and Operations (ATO)","","","",""
"uuid:02468c77-5c64-4df8-9a24-1ed7ad9d1408","http://resolver.tudelft.nl/uuid:02468c77-5c64-4df8-9a24-1ed7ad9d1408","Optimization of Space Trajectories Including Multiple Gravity Assists and Deep Space Maneuvers","Musegaas, P.","Noomen, R. (mentor)","2013","The optimization of high-thrust interplanetary trajectories continues to draw attention. Especially when both Multiple Gravity Assists (MGA) as well as Deep Space Maneuvers (DSMs) are included, the optimization is typically very difficult. The search space may be characterized by a large number of minima and is furthermore very sensitive to small deviations in the decision vector. Various options are available to model these high-thrust trajectories. The trajectory may be modeled using a simple MGA trajectory model as well as using models including DSMs. Both a position and a velocity formulation variant may be adopted and also unpowered or powered swing-bys may be used. These trajectory models were implemented to study the effect of both DSM as well as powered swing-bys. Especially the option to perform DSMs proved to be vital for obtaining good trajectories. Also powered swing-bys may improve the efficiency of the trajectory. The velocity formulation variant proved to be much easier to optimize than the position formulation model. By analyzing the sensitivity and dependency of the various parameters in both models, a proposal for an even better trajectory model is suggested. Also regarding the optimization of these trajectories many options are available. Especially metaheuristics have proven to be very successful in optimizing these trajectories. Various studies have shown the importance of proper tuning of the basic versions of these metaheuristics, which is however often overlooked. This study applied a very rigorous tuning scheme to find the optimal settings for DE, GA and PSO. The results clearly reveal the superiority of DE above other methods. The tuned variants of DE outperformed other settings by one or multiple orders of magnitude, revealing the importance of this tuning scheme. The tuned variants of DE helped to improve a large number of instances in the Global Optimization Trajectory Problem (GTOP) database of ESA. Also the efficiency of these DE variants was shown to be competitive with, and sometimes better than, the best algorithms encountered in literature.","Deep Space Maneuver; optimization; GTOP; high-thrust; interplanetary; trajectory","en","master thesis","","","","","","","","2013-02-26","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:6c752803-6325-4ed9-8b8c-ec52e9fae5db","http://resolver.tudelft.nl/uuid:6c752803-6325-4ed9-8b8c-ec52e9fae5db","MUAC En Route Delay Absorption Capabilities for Schiphol Inbounds","Adriaens, L.M.C.","Hoekstra, J.M. (mentor)","2015","Over the duration of the last year research regarding the en route delay absorption capabilities of the MUAC airspace for Schiphol inbound flights has been performed. Delay absorption currently takes place in the lower airspace, where as a result air traffic controllers and pilots experience increased workloads during one of the most critical periods of a flight. This in combination with the expected fuel inefficiency of delay absorption in the lower airspace resulted in this research to investigate the options of moving delay absorption away from the lower airspace, into the en route airspace. The MUAC airspace is all airspace above FL245 over The Netherlands, Belgium, Luxembourg and West-Germany, encompassing Schiphol inbound flights entering the LVNL airspace (all airspace over The Netherlands up to FL245) from the South, East and North. Traffic data from two sample days was selected (one in high season and one in low season) to reflect the different traffic patterns occuring throughout the year, based on which the planning conflicts were determined. From these planning conflicts the amount of required delay absorption has been obtained, and used as an input to determine which way of en route delay absorption should be used. A range of delay absorption measures has been defined and evaluated: linear holding and dropping for all routes, and detouring and turtling for selected Northern routes. Linear holding means only slowing an aircraft down to the Maximum Range Cruise speed at most, and dropping represents both slowing an aircraft down while lowering its altitude by 2000 ft across its trajectory within the MUAC airspace. Detouring and turtling are the equivalent of linear holding and dropping, respectively, however executed on an extended trajectory. Changing the trajectory of an aircraft may result in conflicts with other traffic, hence it was decided only to use these measures for the Northern routes. This part of the MUAC airspace has a lower traffic density in general, and was the only airspace that could reasonably be provided with detours. The changes were implemented in the scenarios, which were run in the BlueSky Open Source ATM Simulator to gather data on fuel consumption (using Eurocontrol’s Base of Aircraft Data), air traffic controller communications workload, and the number of conflicts with other traffic. The data obtained from the delayed scenarios has been compared to the original scenario to see how the variables were affected by the delay absorption. The delay absorption within the MUAC airspace was found to be 0.4 s/NM for linear holding and 0.7 s/NM for dropping. For the three routes through the Jever sector that were found eligible for detouring and turtling, an additional 8 seconds should be counted for each additionally flown nautical mile. Fuel consumption has been compared to the fuel consumption in the original scenario, from which a slightly reduced fuel consumption was found for linear holding (-0.1%), but a significantly lower fuel consumption for dropping and turtling (-45% and -50%, respectively). This strong reduction in fuel consumption is caused by the earlier initiated descent, during which the aircraft can throttle back to idle thrust. Detouring was found unfavourable in terms of fuel (due to the additional path length), but is nevertheless an effective means of delay absorption. The communication workload was generally found to strongly increase during MUAC peak loadings. Adding more work when a controller is already at his/her busiest is not very desirable, which is why it is unlikely that delay absorption during peak loading can be implemented in the way it was simulated. However, off-peak workloads were sometimes found to be even lower than in the original scenario. This can be explained by the reduction of the number of conflicts, due to which some of the workload assigned for resolving conflicts could be eliminated. During these times of day en route delay absorption would be more than just feasible; it would be very desirable. The ability to predict the change in communication workload has been assessed by computing the correlation between expected and actual change in communication workload, as well as between traffic density and actual change in communication workload, but no relation was found to be strong enough to give a representative indication of the actual change in workload. Overall, the total number of conflicts during linear holding and dropping runs for the low season day were found to lower by 1.1% and 0.4% respectively. The high season saw an overall increase of 0.7% of the total number of conflicts. It is thus expected to be favourable for other traffic if en route delay absorption is performed during low season days, but mostly unfavourable during high season. The Jever sector was the only sector to be equipped with detouring and turtling options, and during all scenarios except for the August linear holding and dropping scenarios a reduction of the total number of conflicts was observed. It can be concluded that when care is taken in when and how en route delay absorption is implemented, it most definitely shows potential to (partially) replace delay methods in the lower airspace.","air traffic control","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration & Operations","","Control & Operations - ATM, Airports & Safety","",""
"uuid:38e5d9ac-8c04-48d5-801f-b0c9308f67fa","http://resolver.tudelft.nl/uuid:38e5d9ac-8c04-48d5-801f-b0c9308f67fa","Delamination of Bonded Repairs: A Damage Tolerance Approach","Pascoe, J.A.","Alderliesten, R.C. (mentor); Rans, C.D. (mentor); Benedictus, R. (mentor)","2012","A model was developed for delamination growth in bonded repair patches under constant amplitude fatigue loading. The model used the finite element method, employing the virtual crack closure technique, to determine the strain energy release rate (SERR) as a function of delamination length. Interaction effects between multiple delaminations, and the effect of delamination shape was also investigated. Fatigue cycling of coupon specimens was performed in order to find a relation between the SERR and the delamination growth rate. A power law (Paris-type) relation was established. Using this relation and the relation between SERR and delamination length, delamination growth predictions were produced. This predictions agreed well with the results of the coupon tests. A further validation by tests on more representative patch repair specimens was inconclusive due to the lack of delamination growth in the patch repair specimens.","fatigue; delamination; adhesive bonding; Strain Energy Release Rate","en","master thesis","","","","","","","","","Aerospace Engineering","Structural Integrity & Composites","","","",""
"uuid:0df034c0-1b97-42d8-9125-bb5050620c98","http://resolver.tudelft.nl/uuid:0df034c0-1b97-42d8-9125-bb5050620c98","The stratos rocket: Design, simulation and production of a record breaking rocket","Uitendaal, M.","Zandbergen, B.T.C. (mentor); Ambrosius, B.A.C. (mentor)","2009","On March 17, 2009, a rocket named Stratos was launched, by Delft Aerospace Rocket Engineering, or DARE in short. The purpose of this rocket was to break the European altitude record for amateur rockets which was 10.7 km at that time. A design of a small sounding rocket, such as Stratos, is a good example of an interdisciplinary challenge. An optimal design is a combination of structures, manufacturability, propulsion, aerodynamics, electronics and many other aspects The Stratos rocket achieved an apogee altitude of 12.551 meters at the Esrange Space Centre, thereby setting a new European altitude record for amateur rockets. A detailed flight trajectory reconstruction is done, whereby differences between simulation and reality are explained. The objective of this thesis is to give a detailed insight in the design, the simulation tools, the production process and the results of the mission. The design philosophy of the Stratos rocket, simulation software and the production planning concept are valuable tools in the development of newer and more powerful rockets, which could ultimately result in a successor of the Stratos rocket.","DARE; rocket; Stratos","en","master thesis","","","","","","","","2009-12-20","Aerospace Engineering","Space Engineering","","","",""
"uuid:985ea160-f12c-472f-9670-fd8ad333ee64","http://resolver.tudelft.nl/uuid:985ea160-f12c-472f-9670-fd8ad333ee64","Flap Performance Improvement by Surface Excitation: A numerical research into active flow control","Dolle, T.J.A.","Bijl, H. (mentor)","2009","The maximum lift coefficient that can be obtained with a certain airfoil is limited by the onset of ow separation. At a certain angle of attack the adverse pressure gradient becomes so strong that the ow can no longer follow the surface of the airfoil and separates, resulting in a decrease in lift and an increase in drag. This maximum lift coefficient can be increased by using high-lift devices like trailing edge aps. However, ow separation still remains the limiting factor. Flow separation control is a solution to this problem. By adding momentum to the boundary layer ow separation is postponed and higher lift coefficients can be reached. In this research active ow separation control by means of a vibrating surface element, a so-called fliperon, is investigated. Both the effectiveness and the efficiency of this flow control method are investigated for the NACA-0015 airfoil at 20 angle of attack and for the NLR7301 airfoil-flap configuration with ow separation from the 35 deflected flap. This research is performed completely numerically with the ow solver Fluent 6. For this research the RANS equations are closed with the k-E turbulence model. Because the fliperon is oscillating during the simulation, the dynamic mesh model is used to rotate the fliperon and to keep the grid quality at a sufficient level. The fliperon was located at a distance of about 20% (flap) chord length ahead of the ow separation point. The length is chosen such that the maximum amplitude of the fliperon tip equals the local boundary layer thickness. Further the shape of the fliperon is equal to the curvature of the airfoil at that location. If the fliperon oscillates above a cavity, the shape of the cavity will also influence the generated vortices. The best results were obtained with a round cavity shape that increases the blowing effect in tangential direction and reduces the amount of additional vorticity that is generated. The performances of a fliperon oscillating above a cavity with a sharp trailing edge and a springboard type fliperon were less promising. The most important parameter of the fliperon motion is the frequency. The frequency influences the size and the strength of the generated vortices. It is important that the generated vortices are sufficiently strong, because they have to travel towards the trailing edge and interact with the vortices that existed there due to the ow separation. Only then the total circulation is improved and the lift coefficient increased. In case of the NACA-0015 a dimensionless frequency F+ of 1.2 turned out to be very effective, while the most effective frequency on the NLR7301 airfoil-flap configuration was 6.0. The fliperon motion should be defined such that the maximum amplitude of the fliperon tip is equal to the boundary layer thickness. Larger amplitudes did not lead to an additional improvement of the lift coefficient, while too small amplitudes did not improve the lift coefficient at all. On the NACA-0015 airfoil the maximum increase in lift coefficient obtained by the application of a fliperon was 20% with respect to the uncontrolled situation. The corresponding momentum coefficient was 0.016, which makes the fliperon both an effective and an efficient method of ow control in this case. On the NLR7301 airfoil flap configuration the maximum increase in lift coefficient was 21.2%, with a corresponding momentum coefficient of 0.144. Although the fliperon is still effective in this case, the momentum is now used less efficiently compared to other types of active ow control. Here the advantage of the fliperon is that it is less complex than several other ow control methods. There are many ways in which the current research can be continued. In future numerical research it would be interesting to perform a large eddy simulation to investigate the influence of the cavity shape on the produced vortices in more detail. Further it is recommended to investigate the effect of different fliperon motions. Since the current research has shown the effectiveness of the fliperon as ow control device, the risk of a wind tunnel experiment is reduced. In such an experiment the simulations can be validated, and the optimal frequency and amplitude ratio can be determined more accurately. Also the influence of 3D effects can be investigated. Furthermore the efficiency of the fliperon can be determined more accurately by measuring the required power.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ed09c971-9d05-427f-99c0-466be819f174","http://resolver.tudelft.nl/uuid:ed09c971-9d05-427f-99c0-466be819f174","Safe Hierarchical Reinforcement Learning: Hierarchical Reinforcement Learning with Safe Space Exploration","Verbist, S.","van Kampen, E. (mentor); Mannucci, T. (mentor)","2017","Reinforcement Learning is a much researched topic for autonomous machine behavior and is often applied to navigation problems. In order to deal with growing environments and larger state/action spaces, Hierarchical Reinforcement Learning has been introduced. Unfortunately learning from experience, which is central to Reinforcement Learning, makes guaranteeing safety a complex problem. This paper demonstrates an approach, named the actor-judge approach, to make the exploration safer while imposing as few as possible restrictions on the agent. The approach combines ideas from the fields of Hierarchical Reinforcement Learning and Safe Reinforcement Learning to develop a Safe Hierarchical Reinforcement Learning algorithm. The algorithm is tested in a simulated environment where the agent represents an Unmanned Aerial Vehicle able to move laterally in four directions using quadridirectional range sensors to establish a relative position. Although this approach does not guarantee the agent to never explore unsafe areas of the state domain, results show the actor-judge method increases agent safety and can be used on multiple levels an HRL agent hierarchy.","","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:a6de0cf0-a562-41e0-8b34-b53b839385d6","http://resolver.tudelft.nl/uuid:a6de0cf0-a562-41e0-8b34-b53b839385d6","CubeSatMicro-Propulsion: Design and Validation of a Micro Bi-Propellant Rocket Motor","Powell, S.J.","Cervone, A. (mentor)","2015","In this MSc thesis, a 4N Bi-Propellant rocket motor was designed using numerical analysis tools. Four motors were built and tested. The results are presented and discussed at length. Combustion instabilities hindered early development. The final design iteration achieved a C* efficiency of greater than 90% in a form factor small enough to fit in a 1U CubeSat module.","Micro Bi-Propellant Rocket Motor","en","master thesis","","","","","","","","","Aerospace Engineering","Space Systems Engineering","","Space Engineering","","52.0167, 4.3667"
"uuid:8145032a-9b1c-48c1-bf46-6f9d7405e5ef","http://resolver.tudelft.nl/uuid:8145032a-9b1c-48c1-bf46-6f9d7405e5ef","Relative Localization for Collision Avoidance in Micro Air Vehicle Teams","Coppola, M.","De Croon, G. (mentor)","2016","A current limitation of using Micro Air Vehicles in teams is the high risk of collisions between members. Knowledge of relative location is needed in order to perform evasive maneuvers from such collisions. We propose an on-board Bluetooth-based relative localization scheme. Bluetooth is a light-weight and energy efficient communication technology that is readily available on even the smallest Micro Air Vehicle units. In this work, it is exploited for communication between team members to exchange on-board states (velocity, height, and orientation), and the strength of the communication signal is used to infer relative range. The data is fused on-board by each Micro Air Vehicle to obtain a relative estimate of the location and motion of all other team members. Furthermore, a collision avoidance controller is proposed based on collision cones. It is designed to deal with the expected performance of the localization scheme by adapting the collision cones during flight and enforcing a clock-wise evasion maneuver. The system was tested with a team of AR-Drones 2.0 flying in a 4m×4m arena. The task requested the AR-Drones to repeatedly fly from wall to wall whilst passing through the center of the arena, hence making collisions highly likely. The system showed promising results. When using two AR-Drones and off-board velocity/orientation estimates, the drones are able to fly around the arena and avoid each other for the entire flight time as permitted by the battery. With three AR-Drones under the same conditions, flight time to collision was 3 minutes. With two AR-Drones flying with on-board velocity estimation, the time to collision was approximately 3 minutes due to the disturbances in velocity estimates. Simulation results show that significantly better results can be expected with smaller units.","Micro Air Vehicles; Bluetooth; Relative Localization; Collision Avoidance; swarm; indoor; drones; team","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:d0715121-d6d3-4816-95b1-4254af5a75c1","http://resolver.tudelft.nl/uuid:d0715121-d6d3-4816-95b1-4254af5a75c1","Optimization of stiffened panels using a combination of FEM and a predictor-corrector interior point method","Deklerck, M.","Abdallah, M.M. (mentor)","2016","Structural optimization, first introduced by Schmidt in 1960, is a rapid growing factor in the development of new aerospace structures. This growth is established by the increase in numerical modelling techniques, cheaper computer power, the increasing cost of production and competition between companies. The combination of both structural optimization and finite element software allowed for the rise of new and more efficient optimization methods provided that the software can performsensitivity analysis. Many programs used in industry today such as BOSS Quattro , PASCO and VICONOPT restrict themselves to basic optimization methods. The goal now is to develop an optimizer for stiffened panels, using a combination of FEM and a more advanced optimization method. Interior point methods have been proven to be more efficient than primal-dual methods for solving sub-problems. Therefore Mehrotra’s predictor-corrector interior point method is used in the version of Zillober. To reach convergence convex approximations are required. The conservative approximation from Fleury’s ConLin provides the basis of many other more advance approximation methods. Therefore this method is chosen to form the initial optimizer. A 2D The FEM model is established using shell and bar elements for the panel and stiffeners respectively. This allows for easy adjustment of the geometry without the need to change the model itself. The bar element properties are defined by the PBAR card rather than the PBARL card in NASTRAN. This avoids the input of fixed NASTRAN specified cross sections with limited design freedom. The sensitivities with respect to stiffener properties are extracted from NASTRAN. These are then converted to the required sensitivities using analytical equations. With all the necessary information available, the inner loop of the optimization process is initiated. Approximations of the constraints, objective and sensitivities are produced. Based on the approximations, the predictor step establishes a maximum step size, which is then adjusted by the corrector step to a more feasible one. This is done iteratively until the duality gap is below a specified limit. Finally a new outer iteration can start if no convergence is reached. Three goals were achieved by analysing of 11 test cases. First the optimizer shows that it can handle different property sets for the stiffeners within the same panel. Secondly, the optimization works for different cross sections. Finally, when performed for similar panels with a different amount of stiffeners, an optimal number is found. The optimization is performed for minimum weight while limited by stress, buckling and design constraints. The results indicate that for 8 out of 11 cases convergence is reached within 12 cycles. Due oscillatory behaviour two other cases converged relatively slow and one did not converge at all. This happens due to the incapability of the optimizer to consider new buckling modes establishing with the adjustment of the parameters. In the end however all three statements were proven outside of the three oscillating cases. For the model that was defined, the optimal amount of stiffeners is 7. Additionally I-beam stiffener provided the most consistent performance with respect to convergence. Finally for this case, although optimizing for different stiffener properties per panel lead to a small reduction in weight, it is not worth the computational effort. So it can be concluded that the optimizer works. On top of this the restrictions on the cross-section defined by NASTRAN were eliminated by extracting a different set of sensitivities and adjusting them using analytical equations. This leads to an optimizer, which can perform size and shape optimization by use of NASTRAN analyses, analytical transformations and an interior point optimization method.","structural optimization; stiffened panel; interior point method; conservative approximation; sequential convex programming","en","master thesis","","","","","","","","","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","Aerospace Structures and Computational Mechanics","",""
"uuid:fe5ea73c-a85b-4a4b-b5d5-fc01d29b2113","http://resolver.tudelft.nl/uuid:fe5ea73c-a85b-4a4b-b5d5-fc01d29b2113","Optical Flow Based State Estimation for an Indoor Micro Aerial Vehicle","Verveld, M.J.","Mulder, J.A. (mentor); Chu, Q.P. (mentor); de Wagter, C. (mentor)","2009","This work addresses the problem of indoor state estimation for autonomous flying vehicles with an optic flow approach. The paper discusses a sensor configuration using six optic flow sensors of the computer mouse type augmented by a three-axis accelerometer to estimate velocity, rotation, attitude and viewing distances. It is shown that the problem is locally observable for a moving vehicle. A Kalman filter is used to extract these states from the sensor data. The resulting approach is tested in a simulation environment evaluating the performance of three Kalman filter algorithms under various noise conditions. Finally, a prototype of the sensor hardware has been built and tested in a laboratory setup. Paper published: Verveld, M.J., Chu, Q.P., De Wagter, C. and Mulder, J.A. “Optic Flow Based State Estimation for an Indoor Micro Air Vehicle” AIAA Guidance, Navigation, and Control Conference, August 2010, Toronto, Canada AIAA 2010-8209, DOI: 10.2514/6.2010-8209","optical flow; sensor fusion; Unscented Kalman filter; bio-inspired flight","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Simulation","","","",""
"uuid:71beb7e4-63fa-4cd2-af76-38d851fb366a","http://resolver.tudelft.nl/uuid:71beb7e4-63fa-4cd2-af76-38d851fb366a","Simulation of Wear in Turbocharger Wastegates","Lin, H.","Turteltaub, S.R. (mentor); Wibmer, M. (mentor); Schmidt, T. (mentor)","2016","This thesis report presents a Finite-Element based methodology for simulating wear damage in the wastegate system of automotive turbochargers. The derived simulation routine is able to reproduce the changes in geometry at contact interfaces of dynamic systems that are subject to relative motion and material ablation. The wastegate is a regulatory device that determines the boost pressure output of a turbocharger. It consists of several distinct components that are in constant relative motion due to external dynamic loads, making their contact surfaces very susceptible to material depletion. The most wear-critical location in the system is the interface between the wastegate's lever and bushing, whose cylindrical outer surfaces slide against each other due to the intended action of the wastegate's regulation actuator as well as unintended effects of exhaust gas pulsations. Severe degradation of the contact surfaces leads to significant changes in the parts' geometry, which inhibits the proper functioning of the device: It becomes increasingly difficult to achieve the optimum part configuration for the requested amount of boost pressure, which in extreme cases might result in device failure. The long-term goal at BMW's department for exhaust system development is to achieve the capability to predict the extent of wear damage at different engine operating conditions. Subject of the current thesis project is the development of a fundamental simulation routine that is able to qualitatively generate the expected geometric changes with a Finite-Element model. The most significant product of this study is a Python script that uses the commercial ABAQUS FE-solver to process the effects of an arbitrary dynamic load within a short period of time, calculate the expected geometric changes, extrapolate them to a large number of load cycles, and transfer the modified geometry back into the original analysis. The script includes three fundamental elements that are essential to any wear simulation concerned with realistic dynamic systems: 1. an accurate representation of the geometric transformation of a three-dimensional model with arbitrary spatial orientation, using a universal method for finding node-displacement directions at part boundaries, 2. a global routine to import and transfer the modified geometry between dynamic and static analyses, and 3. a sensible technique to extrapolate the impact of a load case within a short period of time to represent the effect of a large number of load cycles, such that substantial wear damage - which is typically incurred over several days or weeks - can be simulated with acceptable computation times. The implementation of the individual features have been verified numerically, and it has been shown that the overall approach itself is able to produce legitimate results if certain precautions are taken. The derived ""wear simulation tool"" can be applied to any generic FE-model with a defined load case and therefore provides a practical basis for experimental validation, feature extensions and fine-tuning.","wear; FE-Simulation; wastegate; Archard","en","master thesis","","","","","","","","2021-01-11","Aerospace Engineering","Mechanics, Aerospace Structures & Materials","","","",""
"uuid:424ead9b-50be-4e80-94a9-d041a1418dd3","http://resolver.tudelft.nl/uuid:424ead9b-50be-4e80-94a9-d041a1418dd3","The influence of a bottom camera in indoor ground-segmentation based obstacle avoiding performance for MAVs","Kuijpers, M.W.M.","de Wagter, C. (mentor); de Croon, G.C.H.E. (mentor)","2016","","","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:51d146a0-4d51-47ee-a653-0250ebf089ab","http://resolver.tudelft.nl/uuid:51d146a0-4d51-47ee-a653-0250ebf089ab","Environmental Optimization of Helical Approaches","El Kasri, S.","Visser, H.G. (mentor)","2015","Air tra?c has been growing rapidly for the past few decades and will continue to do so. Airports need to be able to coop with this increase, and thus increase their own capacity. However, due to the landing and departure operations, which take place at low altitudes, high noise levels are generated and a?ect the neighboring communities. This in turn limits the growth of airports that are located near inhabited areas, due to the restrictions on noise levels set by governments for airports. In order to reduce the aircraft noise, a number of solutions have been developed. Some of these solutions are on the aircraft level while the others are on the airport level. A number of solution implemented on the aircraft level are for example, noise e?cient engines and noise reducing fairings. The airport level knows the development of noise abatement operational procedures, such as the CDA. However, there are downsides to such a procedure, like the limitations that it only allows vertical optimization or ?ight at night. Therefore, a new noise abatement procedure has been developed called HeNAP, which stands for Helical Noise Abatement Procedure. As the name suggests it is a procedure where the descent approach is performed by means of a spiral. This allows the aircraft to perform a ?yover the inhabited areas at a higher altitude and perform a descent near the airport by means of a spiral. This would reduce the noise levels perceived by the inhabitants. Earlier research showed a decrease in noise levels but an increase in fuel consumption and time; however, it was never optimized with respect to these factors and at closely inhabited airports. Therefore: The aim of this project is to develop noise-optimal HeNAP approach trajectories using methods from optimal control theory. The noise bene?ts of the optimal HeNAP trajectories need to be assessed through comparison with conventional noise abatement procedures. In addition, an analysis needs to be made of the operational consequences of introducing HeNAP procedures. For this purpose, a GPOPS-based environmental optimization framework for HeNAPs was created. By performing the research on the HeNAP and validating it at the same time, a set of research goals are investigated during this thesis: Develop a code for optimizing the HeNAP trajectories within GPOPS . Assess the in?uence of changing multiple variables such as the altitude, the helical radius and number of spirals performed before landing on the environmental optimization of HeNAP’s with respect to noise impact, fuel usage and time. The framework that is created in GPOPS for the HeNAPs combines a number of models in order to generate noise, namely, a noise model and an aircraft model. This combination results in noise generation of the trajectory ?own, and is processed further in a model that calculates the impact of the noise on inhabited areas. By means of sleep disturbance doseresponse relationship, the impact is converted into the number of awakenings. All of the models interconnect such that a gradient-based optimization is performed to optimize the HeNAP procedure. With the usage of Optimal Control Theory, the cost function, consisting of a weighted noise factor and fuel contribution, is minimized by means of a dynamic process in order to ?nd the optimal controls of the problem. With the help of the Radau pseudospectral method, the dynamics of the problem is accurately approximated. This allows the continuous problem to be discretized to change the in?nite-dimensional problem into a ?nite-dimensional nonlinear programming problem. This can be solved with a numerical solver and results in optimal controls and states that form the HeNAP trajectory. To assess the di?erent changes in altitude, radius and number of spirals and impact of the resulting solutions on the environment, for the majority of the time a single-phase optimization is used. However, in order to assess sections of the HeNAP trajectory, multi-phase optimization is sometimes used as well. The help of these optimizations simulates di?erent HeNAP routes until the most favorable one is found. A case study is performed in a highly inhabited area around Amsterdam Airport Schiphol. During this case study, a number of routes are simulated and investigated. Di?erent altitudes, radii and number of spirals are compared while adhering to the di?erent airspace regulations. Over 300 simulations have been performed, as this was an intensive trial and error process, eventually resulting in a number of cases over four di?erent optimization problems. These problems are de?ned as followed, minimum time optimization problem, minimum fuel optimization problem, minimum time and noise abatement optimization problem and ?nally minimum fuel and noise abatement optimization problem. The cases that are solved for these problems are as followed: Case 1: is a CDA procedure that is performed at an altitude of 7000 ft and minimum ILS approach distance of 6.2 NM. Case 2: is the ?rst HeNAP simulation and is run with an altitude of 7,000 ft and one spiral. Case 3 the altitude is changed from 7000 ft to 10,000 ft. Case 4 the altitude of case 3 is still in e?ect and the number spirals is changed from 1 to 2. The results of these cases are all comparable throughout the di?erent optimization problems. All of them reveal that the CDA procedure is the most favorable procedure as it has the least number of awakenings, fuel consumed and time needed to land. However, when relocating the population around the airport to the ?rst part of the trajectory it yields better results. Case 3 is then the most favorable case, with promising results. The changes in altitude for the HeNAP showed that by having a higher initial altitude the number of inhabitant awakened is reduced, however when the number of spirals is increased this e?ect is dismissed. The following recommendations might help improve/show more of the HeNAP possibilities. The ?rst recommendation that can be given, is to use the results that are found within this thesis and use them as a basis for the same research but within another area that might be less inhabited than the area around AAS and where the night-curfew is also in e?ect. Another recommendation that can be made is to add the wind and weather conditions to the GPOPS tool in order to get results that are more realistic and increase the reliability of the results and feasibility of the trajectories performed. A ?nal recommendation is to introduce better methods to avoid local minima within the GPOPS tool, this result in unnecessary delays. Nevertheless, the HeNAP procedure has great future possibilities only not within the Netherlands.","HeNAP","en","master thesis","","","","","","","","","Aerospace Engineering","ATO","","","",""
"uuid:59356102-9032-44b4-84a0-f798effc823c","http://resolver.tudelft.nl/uuid:59356102-9032-44b4-84a0-f798effc823c","Buoyant Aerobot Design and Simulation Study: BADS","Van Dosselaer, I.","Zandbergen, B. (mentor)","2014","Aerobots, and more specifically buoyant aerobots, are not that common in space or planetary exploration. There is however a small community of scientists and engineers who are exploring these technologies. “Aerial vehicles used in planetary exploration bridge the scale and resolution measurement gaps between orbiters, which have global perspective with limited spatial resolution, and landers which have local perspective with high spatial resolution, thus complementing and extending orbital and landed measurements.” This indicates that an aerobot can provide a substantial scientific return far beyond the alternatives like an orbiter, lander or surface rover. Here on Earth buoyant aerobot technology is flown daily by meteorological institutes. A buoyant aerobot is nothing else than a type of balloon filled with a buoyant gas lighter than air. For the simple release of an atmospheric balloon however, a certain expertise is required. Researching atmospheric balloons lead to the exploration of these balloons, airships and alike for planetary missions. Understanding the behavior of a scientific balloon here on Earth definitely increases the insight of balloon behavior on another planet. Organizations across the world have been working on vertical flight simulation programs to estimate the balloon’s time of ascend and floating altitude. Over the years improvements were made and extensive programs were developed which included; planetary atmospheric models, 3D trajectory planning, buoyant gas selection, balloon envelope materials selection, propelled flights, etc. This thesis presents the Buoyant Aerobot Design and Simulation tool BADS. The tool has been modeled as much as possible towards the current professional aerobot flight simulation programs. The program makes use of Matlab coding for the aerobot design and trajectory simulation and includes the following databases and parameters to specify the aerobot’s design and flight; 4 atmospheric models (Earth, Mars, Venus and Titan), 4 balloon shapes (Sphere, Oblate Pumpkin, Prolate, Prolate Airship), 4 balloon pressure types (Zero-Pressure, Super-Pressure, Over-Pressurized Zero-Pressure, Montgolfier), 15 envelope materials, 71 envelope coatings. The validation of the tool has been achieved through thorough testing and comparison against existing flight simulation tools and specific aerobot design data. A sensitivity study proved that the assumptions made in BADS are similar to those in other programs and that any discrepancy effect, if present, can be minimized.","Aerobot; Buoyant; Simulation; BADS; Design","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","Space Systems Engineering","",""
"uuid:db849c70-8d1c-49d0-898d-cbc89d20b693","http://resolver.tudelft.nl/uuid:db849c70-8d1c-49d0-898d-cbc89d20b693","Delamination Growth Predictions of Non-Uniform Sandwich Details","Zhang, D.","Alderliesten, R.C. (mentor); Branner, K. (mentor); Joosse, P. (mentor)","2016","Sandwich composite is commonly used as a material of wind turbine blades. In order to meet the practical needs, the design of sandwich always contains some designed-in imperfections, like ply drop of facing laminates, core with resin grid and so on. These unavoidable designed-in imperfections may induce delamination problems and result in huge economic loss. This Master thesis project aims to predict the delamination growth of sandwich with facing ply drop. Di↵erent failure modes of sandwich are studied; the potential relation between facing ply drop and delamination is clarified. Virtual Crack Closure Technique (VCCT) based delamination growth analysis is applied in numerical study. Pristine sandwich and ply drop sandwich with face/core interface crack are tested. After previous simulation results are compared with experimental results, a new simu- lation method combining VCCT and post-buckling delamination analysis is established. However the numerical simulations do not match with experiments well and need to be improved.","","en","master thesis","","","","","","","","2021-08-23","Aerospace Engineering","Aerospace Structures & Materials","","EWEM European Wind Energy Master","",""
"uuid:455ec2e9-a36b-445c-a9ae-ef6acbbf58f8","http://resolver.tudelft.nl/uuid:455ec2e9-a36b-445c-a9ae-ef6acbbf58f8","Preliminary Navigation Analysis for the Flyby Tour of ESA’s JUICE mission: An investigation on the trajectory correction maneuvers design","Gastaldello, N.","Dirkx, D. (mentor)","2016","The JUICE spacecraft is an ESA mission to the Jovian system that will be launched in 2022. It will collect scientific data about Jupiter and its Galilean moons thanks to a flyby tour of Europa, Ganymede, Callisto and a final Ganymede orbiting phase. A high number of flybys will be performed with minimumaltitudes of 200 km. The tracking of the spacecraft during the flybys allows the estimation of the position of the spacecraft and the moons; in particular the knowledge of the moons positions can improve noticeably. However, due to the uncertainties in the positions of the moons and the spacecraft itself, a robust trajectory control is required for precise flyby targeting, to ensure that the nominal mission plan is achieved with the required margins. A preliminary navigation analysis for the mission JUICE has been developed, with the objective of the studying the influence of the spacecraft and moons positions uncertainties on the trajectory correction maneuvers (TCMs). The navigation analysis is composed of an orbit determination covariance analysis and a guidance simulator. The covariance analysis determines the standard deviations of the parameters of interest, (spacecraft and moons initial states) from the observations computed along the trajectory of the spacecraft. Different parameters can be chosen for the covariance analysis in order to represent different mission conditions and tracking data performances. The guidance has the purpose of computing the necessary actions to bring back the spacecraft to the desired path after the nominal one has been perturbed with the spacecraft and moons positions uncertainties; these action are the TCMs, which are represented by a ¢V due to the high thrust engine of JUICE. Three different targeting algorithms have been implemented for the guidance, with different characteristics of accuracy and speed. Two statistical maneuvers per flybys have been implemented, the pre-flyby (targeting) maneuver and the post-flyby (cleanup) maneuver. The navigation analysis is performed using a Monte Carlo method, sampling with a normal distribution the results of the covariance analysis to obtain perturbed trajectories; statistical results are then computed. This is necessary because the results of the OD are to be interpreted in a statistical way; the real perturbed trajectory is always affected by an uncertainty. A sensitivity analysis with respect to the tracking data types has been performed for the covariance analysis. The results show that for JUICE an uncertainty of the level of a few hundred meters can be reached, if range and VLBI data are used. However these results are just indicative since Doppler data have not been included in the simulations. The uncertainty in the positions of the Galilean moons obtained thanks to the flybys depends highly from the tracking strategy used and the data types. With themost realistic configuration (tracking interrupted before the flyby and inclusion of all the past data), the level of uncertainty can arrive to a few tens of meters, with data accuracies of 0.2 m for the range and 0.1 nrad for the VLBI. These results are for the formal errors and it is known that they are usually overly optimistic; the true error will be higher. Moreover, the importance of optical data for a further uncertainty reduction has been proven. The improvement of the Galilean moons uncertainties along the Tour as data are continuously added is also observed. Sensitivity analysis with respect to the maneuver time and the maneuver execution errors have been performed for the Monte Carlo navigation analysis. The maneuver time has the highest influence on the size of a maneuver; each flyby presents a time for which the ¢V required to correct the trajectory is minimum. Very often this time is of 3 days before the flyby (for the targeting maneuver), as found often in literature; however many flybys have this minimum around 2 days before the flyby. The maneuver execution error has a limited impact on the total mission ¢V , but it can decrease the accuracy of the targeting, causing an higher miss distance at flyby. The total ¢V required to performthe flyby Tour varies considerably upon the different parameters chosen; using current level accuracies (1mfor the range and 1 nrad for VLBI) and a maneuver time of 3 days before (and after) the flyby, the result is ¢V Æ 13.5 m/s (around 0.67 m/s per flyby). This value includes the targeting and cleanup maneuvers; it is easily obtainable by the propulsion system of JUICE, concluding that it is possible to correct the trajectory for the uncertainties of JUICE and the moons with a small effort.","","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","Astrodynamics & Space Missions","",""
"uuid:dd051acf-7adf-46a2-8223-b0bb16824518","http://resolver.tudelft.nl/uuid:dd051acf-7adf-46a2-8223-b0bb16824518","Airport Surface Planning under Uncertainty","Siebers, J.A.","Sharpans'kykh, O.A. (mentor); Spaan, M.T.J. (mentor)","2017","This thesis describes a solution to the Ground Movement Problem, formulated by Atkin et al. in 2010. It is described as a routing and scheduling problem and involves directing aircraft to their destinations in a timely matter, with the aim to either reduce the overall travel time and/or to meet some target time windows. A Markov Decision Process is used as an agent-based approach to capture operational uncertainties of influence on travel time. Optimization of routing and timing is performed in order to minimize travel time and maximize compliance to target times at destination. Propagation uncertainty, found through analysis of historical data, is used in order to provide optimized and robust planning. Results show that part of variation in travel time is captured, but also robustness of the model is shown to differences in start time and execution. Therefore, at any time moment and at every piece of taxiway, an optimized plan is available without the need for recalculation.","Agent-based; Uncertainty; Markov Decision Process; Airport; Routing; Timing; Traffic Planning; ADS-B","en","master thesis","","","","","","","","2017-01-27","Aerospace Engineering","Control and Operations","","","",""
"uuid:fadcbb6a-67f8-419b-9e4f-a546866c738a","http://resolver.tudelft.nl/uuid:fadcbb6a-67f8-419b-9e4f-a546866c738a","Development of a Wave Drag Prediction Tool for the Conceptual Design Phase","Vargas Jimenez, J.A.","Vos, R. (mentor)","2015","The goal of this thesis is to improve the wave drag estimation techniques in the aircraft conceptual design. Based on the most relevant methods, among those developed in the past $60$ years, three methods are proposed as an attempt to include more design variables and improve the accuracy of the wave drag prediction. The proposed methods include the use of supercritical airfoils and the cross sectional area distribution of the aircraft as port of the wave drag estimation. The proposed methods are compared to experimental drag data, available in the literature, of four high-subsonic conventional transport aircraft. An accuracy analysis is performed evaluating how well each method predicts the drag divergence Mach number, the wave drag at Mach number 0.8, and how well the predicted curve fitted with the experimental data. The analysis led to the conclusion that the results of the Delta method shows better agreement with the experimental data than the proposed methods. The state of the art techniques and the proposed methods have been implemented and integrated into a conceptual design tool, as a new module. The module functionality, including its settings, inputs, outputs and functions are also described in this document.","wave drag","en","master thesis","","","","","","","","","Aerospace Engineering","Flight performance and propulsion","","Flight performance and propulsion","",""
"uuid:3c87afd7-5275-4c15-96f0-3d77fde517b1","http://resolver.tudelft.nl/uuid:3c87afd7-5275-4c15-96f0-3d77fde517b1","Design of the Deployment Mechanism for the Primary Mirror Elements of a Deployable Space Telescope","Van Putten, B.T.","Kuiper, J.M. (mentor)","2017","Applications for space telescopes require ever higher resolutions. This is driving space telescopes to keep getting bigger as they need a large primary mirror to achieve these resolutions. Such large instruments are also heavy and cost a lot of money to launch. Current launchers offer a limited amount of space making it impossible to launch a telescope with a monolithic mirror larger than five meters in diameter. Over the last few decades, the interest in utilizing segmented deployable mirrors in order to achieve larger effective apertures has steadily increased. The Space Systems Engineering department of the faculty of Aerospace Engineering at the TU Delft started working on a deployable synthetic aperture telescope in 2014 and is now continuing the research in cooperation with ESA, TNO and ADS. The optical design of the Deployable Telescope System (DTS) is already in an advanced stage. However, much work remains to be done. One of the main challenges is designing a highly accurate and stable deployment mechanism for the primary mirror elements of this instrument. Position and orientation tolerances for the primary mirror elements have been determined in a previously performed top down systems engineering approach. The most critical requirements are on the piston and tilt of the mirrors. The required piston and tilt accuracies of each mirror element are 2[μm] and 2[μrad] respectively. The key to achieving accurate deployment is to separate the deployment motion into a course deployment of the mirror segments, followed by a separate fine calibration stage that allows for accurate tip, tilt and piston control. From the literature study that precedes this thesis proposal, it was concluded that it is a challenging task to design a deployment mechanism for the deployable telescope that can offer sufficient accuracy. The goal is to design the mechanism such that it is reliable, lightweight and suitable to the current optical design. The design should allow for the mirror segments to be folded close to the telescope body so that the stowed instrument fits within a minimal envelope. This thesis covers the design process for the deployment mechanism for the primary mirror elements of the telescope. Successfully designing a deployment mechanism with all these qualities will be a big step forward in realizing the DTS. Due to the deployable design, this telescope can be an order of magnitude less heavy and requires a lot less space inside a launcher when compared to current telescopes. The concept will also allow for the development of telescope mirrors much larger than five meters in diameter.","","en","master thesis","","","","","","","","2022-04-13","Aerospace Engineering","Space Systems Engineering","","","",""
"uuid:20f07d7e-3d2d-498a-898a-e165affa6c12","http://resolver.tudelft.nl/uuid:20f07d7e-3d2d-498a-898a-e165affa6c12","The Ballistic Deployment of Asteroid Landers","Van wal, S.","Mooij, E. (mentor); Scheeres, D. (mentor)","2015","The deployment of passive, spherical lander pods provides a low-cost, low-risk technique for measuring the (sub-)surface of asteroids and comets. In this masters thesis, we numerically investigate the feasibility of such pods through the development of simulation software. This software models the complex gravity field of asteroids, as well as collisions, contact motion, and rocks on the surface. After performing extensive verification and validation, we test deployment to the unitary asteroid 25143 Itokawa and the binary system 1999 KW4.","asteroid; lander; comet; deployment; ballistic; aerospace; space; spacecraft","en","master thesis","","","","","","","","","Aerospace Engineering","Spaceflight","","Space Exploration","",""
"uuid:086568bb-c951-479a-b2bf-0cf43d238119","http://resolver.tudelft.nl/uuid:086568bb-c951-479a-b2bf-0cf43d238119","Thickness-Tailored Flexible Airfoil for Improved Aeroelastic Stability Behaviour","de Vries, R.","De Breuker, R. (mentor); Sodja, J. (mentor)","2016","The general trend in the aerospace industry is to optimise lightweight and highly flexible wing structures made of composite materials. This flexibility gives rise to static and dynamic aeroelastic instability problems. Research by Kim and Lee, Murua et al., and Drazumeric et al. have proven that chord-wise flexibility has a significant effect on the aeroelastic characteristics of an airfoil [1–3]; including the aeroelastic instability boundaries. Drazumeric et al. have numerically and experimentally shown that by adding chord-wise flexibility the stability boundaries could be increased up to 79.2% in the region of bimodal flutter behaviour, meaning that conventional section flutter and plate flutter occur simultaneously. It has been identified that the two-dimensional aeroelastic characteristics of flexible airfoil has been studied for constant stiffness flexible airfoils only. The present project will take the next step by assuming a piecewise constant thickness distributed flexible trailing edge. An elastically supported rigid airfoil shaped leading edge with attached a flexible composite plate was considered. The piecewise constant thickness distribution of the flexible plate was optimized for increasing the critical flow velocity at which the aeroelastic instabilities occur. An aeroelastic model has been developed to determine the aeroelastic characteristics of an elastically supported airfoil with attached a flexible piecewise constant thickness distributed trailing edge. The thin airfoil is assumed to harmonically oscillate with small amplitudes. The aerodynamic forces and moments are calculated by adopting the Küssner and Schwarz model which relates the pressure distribution over the airfoil to the downwash [4]. The transverse motion of the plate is modelled as an Euler-Bernoulli beam under the assumption that no span-wise deformations in the flexible trailing edge occur. The aeroelastic stability boundary is obtained by solving a complex eigenvalue problem in matrix form. The solutions to the system of equations are obtained as couples of the reduced frequency with the corresponding critical flow speed. The aeroelastic model is used to tailor the thickness distribution of the flexible trailing edge to optimise for the critical flow speed. Optimisations are executed for airfoil sections with conventional sectional parameters and with unconventional sectional parameters. In all cases it can be seen that a convergence in critical flow velocities was obtained for a trailing edge divided in two sections with a constant thickness. Depending on the length of the flexible trailing edge an increase up to 76% was achieved for airfoils with unconventional parameters, while for airfoils with conventional parameters a limited increase up to 4.1% was achieved.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:c57819ca-09c5-4cee-9846-29a13c121034","http://resolver.tudelft.nl/uuid:c57819ca-09c5-4cee-9846-29a13c121034","Collision analysis and mitigation for distributed space systems","Florijn, D.W.","Sundaramoorthy, P.P. (mentor); Gill, E.K.A. (mentor)","2015","Collision analysis and mitigation performed for the QB50 mission. The aim of this thesis report is to identify which mitigation strategies are most suitable for a network of uncontrollable satellites. Furthermore, the aim is to set-out a method to determine the collision probability for a network of uncontrollable satellites, and identify the parameters that influence the collision probability. These methods are applied to the QB50 mission; to find a scenario where the collision probability is lowest. An alternative method is developed by the author to calculate the Gaussian probability, which is applicable for small satellites. As the size of the satellites decreases relative to the error ellipsoid, the probability at a certain moment in time becomes more equal to the probability at the center of the combined sphere (assuming spherical satellites). Now, instead of dealing with a cumbersome volume integral through the combined error ellipsoid, the collision probability can be approached by a line-integral times the area of the combined satellites’ bodies. Four ideal deployment angles for the QB50 mission were found located in a plane of zero pitch and at yaw angles of 34?, 146?, 248?, 326? measured from velocity vector of the upperstage.Deploying at zero pitch has the effect that the phase between the cross-track and radial separation is half the orbital period. This has the consequence that, when either the cross-track separation is zero, the radial separation has its maximum and visa versa. This can also be identified as (anti-)parallel alignment of relative eccentricity and inclination vectors. Synchronization of the motion at times where the deployment is half or equal to the orbital period should be avoided. For these satellites the amplitude radial and cross-track separations are small. Furthermore, the relative perturbations between these satellites is large, decreasing the offset of the radial motion. This causes the radial and cross-track separation reach zero at equal time. Synchronized satellite increase the collision probability significantly. Both Patera’s method and the line-integral method are applied to a full-scale simulation for the QB50 mission. Multiple scenario’s are chosen for the full-scale simulation. The two scenario’s with the lowest probability are sequential deployment at one of the ideal angles and alternating deployment between two opposite ideal angles. These fall below the threshold value of 10?4, a value used by the German Space Operations Center (GSOC).","collision; analysis; mitigation; qb50; patera; gaussian; satellites; distributed space systems; space; space engineering","en","master thesis","","","","","","","","","Aerospace Engineering","Space Flight","","Space Systems Engineering","",""
"uuid:faa2c6dc-e5ca-4486-b607-d963f650dad2","http://resolver.tudelft.nl/uuid:faa2c6dc-e5ca-4486-b607-d963f650dad2","Improved Flexible Runway Use Modeling: A Multi-Objective Optimization Concerning Pairwise RECAT-EU Separation Minima, Reduced Noise Annoyance and Fuel Consumption at London Heathrow","van der Meijden, S.A.","Roling, P.C. (mentor); Visser, H.G. (mentor)","2017","A minimization of disturbance caused by aircraft noise events and a reduction of fuel consumption during the initial and final phase of flight. These are the two objectives that play an important role in the Flexible Runway Allocation Model. By taking into account fuel consumption alongside noise annoyance, this model enables to analyze and optimize runway allocation from a broader perspective. This study aims to identify the improvements that can be made with respect to the initial Flexible Runway Use Model. Accordingly, these enhancements should be implemented and quantified in order to establish the Improved Flexible Runway Allocation Model. The improvements that are found in this study relate to both objectives in the mixed integer linear programming optimization as well as particular linear constraints. A major contribution is made to the runway occupancy constraint, which has shown a transition from a single aircraft computational method to a pairwise flight separation approach based on RECAT-EU. The proposed Improved Flexible Runway Allocation Model is applied to a case study that represents daily operations at London Heathrow Airport. This model shows that, by assigning a small delay to inbound and/or outbound flights, significant contributions can be made with respect to noise annoyance in the vicinity of the airport as well as the overall fuel consumption from the airline’s perspective. By allowing opposite direction operations, flexibility is added to the use of the airport’s runway ends, which results in a more efficient utilization of the available capacity. The results of this analysis are visualized by means of a Pareto front, indicating the Pareto optimal solutions to a runway allocation assignment based on a differentiation in objective weights.","runway; allocation; capacity; MILP; Linear Programming; Heathrow; London; optimization; fuel; noise; noise annoyance; Pareto; RECAT-EU; separation minima; opposite direction operations; flexible; flexible runway allocation","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Air Transport & Operations (ATO)","",""
"uuid:82986b0c-2b29-462f-8c6f-746236259ea3","http://resolver.tudelft.nl/uuid:82986b0c-2b29-462f-8c6f-746236259ea3","Synthesis of an Aircraft Featuring a Ducted-Fan Propulsive Empennage","Van den Dungen, N.H.M.","Vos, R. (mentor); Van Arnhem, N (mentor)","2017","A study is done to investigate the feasibility of the conceptual design of the Delft University Unconventional Configuration (DUUC), an aircraft featuring a ducted-fan propulsive empennage. This research is focused on ducted-fan performance analysis and aircraft longitudinal static stability and balance estimation. The aircraft design Initiator program is used to develop models of the DUUC, and a similar-sized conventional turboprop reference aircraft. A performance comparison of the baseline models, combined with a sensitivity analysis to the main ducted-fan design parameters, is performed to study the effect of the DUUC concept on the overall aircraft design.","stability & balance; DUUC; ducted fan; propuslive empennage; aircraft design; initiator","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance & Propulsion","","","",""
"uuid:db9e8daf-dede-4915-9425-df4bc9706c12","http://resolver.tudelft.nl/uuid:db9e8daf-dede-4915-9425-df4bc9706c12","An exploration into the potential of microturbine based propulsion systems for civil Unmanned Aerial Vehicles","Marcellan, A.","Visser, W.P.J. (mentor)","2015","A Master Thesis Research has been undertaken with the goal of investigating the potential of micro gas turbines as propulsion system of choice for small Unmanned Aerial Vehicle (UAV) used in civil applications. The UAV market is likely to develop great economic and technological importance on a near future because of the wide variety of applications and the added value related to the unmanned vehicles. In this regard, research focused on improving UAV capabilities is strictly related to UAV propulsion systems; as a matter of fact, aircraft performance is dependent on the mass of the power-plant and its specific fuel consumption since these can have a very significant effect on the reduction in size or increase in range of the UAV. An Exploration Study is performed both in the fields of UAV technology and of Micro Gas Turbine technology. These two areas are covered in order to understand the possible advantages and limitations of micro gas turbine engines compared to alternative propulsion concepts (e.g. electric and reciprocating engines) when used for a specific application. After the identification of a significant Case Study, a conceptual design of a high-potential UAV micro gas turbine based propulsion system is performed. Prediction of scale effects is important within the framework of turbine conceptual design where the power output is varied in order to optimize the mission performance in which the turbine is integrated. To this end, engine cycle optimization using Gas turbine Simulation Program (GSP) is carried out. Furthermore, an ""Aircraft Study"" is performed in a correlated Master Thesis Project in which the aerodynamic and flight performance model of a baseline UAV is developed. After the model validation, results from the micro gas turbine model are integrated and the performance of the new UAV configuration is investigated. The final engine configuration is a 77 kW dual shaft turboprop which is further implemented into the UAV platform redesigned accordingly to the reduced weight and improved performance. The mission model estimates for this configuration an endurance of 28.7 hours, with a range of 4419 km and a payload weight of 250 kg, with a significant fuel reduction of 12.5% compared to the original UAV configuration. The effect of power setting at cruise and the engine weight reduction allows the turboprop to arguably showcase overall better mission performance. As a result of the work carried out in this Master Thesis Project, a valuable tool for understanding the contribution of micro gas turbine integration into civil UAV has been developed.","microturbine; UAV; civil Applications","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:6c0ba4d7-f713-44b4-865a-484316d4e860","http://resolver.tudelft.nl/uuid:6c0ba4d7-f713-44b4-865a-484316d4e860","Design of a blade section featuring passive load alleviation capabilities resulting from variable stiffness morphing structures","Cavens, W.D.K.","De Breuker, R. (mentor); Garcia, N. (mentor); Arrieta, A. (mentor)","2015","The main objective of this MSc thesis project is to investigate the load alleviation potential of a variable stiffness bi-stable morphing blade section under extreme gust conditions by designing such a blade section. This project builds on the work of Arrieta et al. and Kuder et al. and is based on the DU 93-W-210 airfoil. The bi-stable element design by Kuder et al. was carried over. The aerodynamic codes XFOIL, Q3UIC and RFOIL were compared and validated with wind tunnel data and more advanced Computational Fluid Dynamics results. The aeroelastic Abaqus model by Kuder et al. was modified in order to accommodate for this project. The effects of an extreme operating gust were studied and quantifed. Especially at cutout conditions, the impact of a gust was found to be profound. Furthermore, dynamic stall effects during a gust were found to be significant at high angle of attack. It was demonstrated with a parametric study that trailing edge flaps can alleviate a significant amount of the load increase due to a gust. A morphing trailing edge mechanism was presented. This mechanism consists of a morphing trailing edge flap which is restrained from rotation by a bi-stable plate. Upon reaching a critical flap hinge moment, the bi-stable snaps from the stiff to the flexible state which allows the trailing edge flap to morph passively and hence alleviate load. The flap hinge moment behaviour of small flaps was found desirable for passive morphing and originates from boundary layer separation. A locally compressible profile skin was found to be required in order to achieve load alleviation. Therefore, a corrugated skin was implemented on the suction side of the profile near the trailing edge. Two morphing blade sections were presented, one with a large flap (20.59% chord) and one with a small flap (13.19% chord). The effectiveness of the bi-stable restraining mechanism was demonstrated. The small and large flap exhibit relatively similar amounts of load alleviation which indicates that the small flap is more efficient. The instantaneous lift reduction is around 7% at rated conditions and 17% at cutout conditions. This means that trailing edge flaps are less effective at high angle of attack in separated flow conditions. However, the amount of alleviated load increases after snap-through with increasing wind speed. Finally, the dynamic response of an instantaneously morphing flap was addressed. It can be concluded that passive load alleviation was achieved. One of the critical elements for this load alleviation was the implementation of a corrugated skin. It is deemed that the presented designs can be optimised further to achieve even more load alleviation. However, this study indicates that there is a potential for a morphing passive load alleviation mechanism which reduces the impact of extreme gusts and potentially allows for a reduction in blade mass which in turn can induce a reduction in wind energy cost.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","EWEM","",""
"uuid:3f3a68c7-1254-4c68-bd94-ee232e4db55a","http://resolver.tudelft.nl/uuid:3f3a68c7-1254-4c68-bd94-ee232e4db55a","Development of a Finite Element based Strength Calculation method for Curved Composite Laminates","Heijmer, M.B.M.","Shroff, S. (mentor)","2016","An accurate corner strength modelling method is required at Fokker Aerostructures to design canisters (missile launch tubes) with rounded corners for an internal pressure load case. To this end a combination of experiments and calculation methods has been developed that enable to predict the corner strength more accurately. Internal pressure experiments on canisters are costly; hence four point bending of a curved beam was used to represent the internal pressure experiment. The bending moment in the corner is such that the radius of the curved laminate increases while deforming. This causes Inter Laminar Tensile (ILT) stress in the corner, with its magnitude depending on the ratio of inner radius to thickness (Ri/t). As a result of ILT stress the curved laminates fail in a delamination failure mode. The Inter Laminar Tensile Strength (ILTS) of four different adjoining ply orientations was determined experimentally. These ILTS values were much higher than expected based upon results from previous experiments at Fokker. The reason for this underestimation was that the specimens used in the previous experiments were made by towpreg filament winding instead of prepreg hand layup, and had ratios that might have been too high to determine the ILTS. Based upon simulation and literature study it was decided that modelling of delamination initiation without modelling delamination propagation can be applied to determine the strength of a corner specimen without initial delaminations. Therefore stress based failure criteria were chosen for failure prediction. These criteria were applied to a 3D stress field calculated using FEA with solid elements, such that all stress components, and the effect of finite width was taken into account. Subsequently, the strength calculation method was validated by applying it to validation specimens with higher Ri/t ratios. For both the [90]n and the crossply layup the highest accuracy was obtained using the maximum stress criterion, of 3% and 6% respectively. Based on the simulation results it was concluded that for both of these specimens delamination occurred as a chain reaction after initiation by fiber failure or matrix cracking. Further improvements could be made by validating the current method for different layups, other materials and production processes.","Composite; Curved beam strength; Finite Element Analysis; Validation","en","master thesis","","","","","","","","2021-09-13","Aerospace Engineering","Aerospace Structures and Computational Mechanics","","","",""
"uuid:6f420fc6-6085-462d-9f53-2253eaf6b611","http://resolver.tudelft.nl/uuid:6f420fc6-6085-462d-9f53-2253eaf6b611","Ab Initio-Thermodynamic Modelling of Precipitation Processes in the Aluminium 7XXX Family","De Jong, M.","Sluiter, M.H.F. (mentor); Van der Zwaag, S. (mentor); Rivera, P.E.J. (mentor)","2010","This thesis studies precipitation processes in the Aluminium 7000 series using quantum mechanical total energy calculations. The emphasis is laid on studying the energetics of the various transient phases involved in precipitation of the 5 most important strengthening precipitates. Bulk, strain and interface effects are studies separately, in conjunction with a traditional CALPHAD-approach to phase stability modeling.","First principles; Thermodynamics; Ab initio; Precipitation; Metastable phases; Density Functional Theory; Phase transformations","en","master thesis","","","","","","","","","Aerospace Engineering","Novel Aerospace Materials","","Computational Materials Science","",""
"uuid:cebf97d0-4c72-49fd-ab11-5d0f0fbb8923","http://resolver.tudelft.nl/uuid:cebf97d0-4c72-49fd-ab11-5d0f0fbb8923","Wind Farm Effects on the Atmosphere: A meso-scale and numerical modeling of the offshore boundary layer through parameterized turbine rotors","Striedinger, A.M.","Hartmann, H. (mentor); van Bussel, G.J.W. (mentor); Bierbooms, W.A.A.M. (mentor)","2014","In this study, the offshore wind farm effects of Thanet (300 MW) in the U.K, and of Middelgrunden (40 MW) in Denmark were analyzed in a meso-scale numerical prediction model, whilst working at MeteoGroup. For the final analysis of Middelgrunden, the model is validated with measurement data from Middelgrundens Vindmøllelaug. The model uses parameterizations for the atmospheric flow, surface physics effects, and a turbine scheme based on a Drag disc concept. The scheme uses turbine data in relation to changes in the turbulent kinetic energy of the flow as it passes through the rotors. The free stream is affected by the farm through local reductions of turbulence intensity aligned in front and in-between turbine rows, and the regions affected are as high as the turbine themselves. Wind speed near the surface is found to increase inside the wind farm (a phenomena often times unexpected), transporting turbulence downstream by advection. The simulations indicate that the added turbulence form turbine rotors promotes strong vertical transport of turbulent kinetic energy up in the atmosphere, and directly above the wind farms. Further, horizontal momentum exchanges is proven to be negligible behind turbine rotors in the downstream of the farm due to the lack of proper turbulent advection. Local meteorology is affected as the air suddenly expands above the farm, increasing the height of the planetary boundary layer as a consequence. The expansion creates a vertical temperature gradient, separating cooler air masses above the rotor area, from similarly hotter air masses near the surface. The gradients obtained varied from -0.2OC to +1OC. Surface to air heat fluxes are lessen inside turbine arrays, whilst increased downstream in the farm wake. Additionally, the Local flow patterns are found to be crucial in determining the shape and a sense of direction of the wake downstream. Finally, the meso-scale model with turbine scheme is found to mimic the interaction between the turbines and the atmosphere, to some extent due to uncertainties in the horizontal gradient of turbulence intensity. Further improvement is needed to produce a precise power forecast, which also depends on the model input data, such that a focus of attention is the correct prediction of wind direction. Further, the accurate representation of the turbine layout and number of turbines per grid location are essential to detail the turbulence inside the farm, but not for analyzing meso-scale effects. Winds speed and power ratio profiles were found in agreement with measurements.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","Sustainable Energy Technology","",""
"uuid:f92da57f-55df-4109-9f8a-8c7c2b220c6a","http://resolver.tudelft.nl/uuid:f92da57f-55df-4109-9f8a-8c7c2b220c6a","Finite Element Analysis of Inflatable Structures Using Uniform Pressure: Inflatable beam validation and leading edge inflatable tube kite structural modeling in Madymo","Schwoll, J.F.J.E.M.","Ockels, W.J. (mentor); Schmehl, R. (mentor); Bergsma, O.K. (mentor); Breukels, J. (mentor); Tijssens, M.G.A. (mentor)","2012","Kite wings might be the future in sustainable electricity generation. Delft University of Technology developed a concept with a flexible Leading Edge Inflatable (LEI) kite to generate the energy, which can maneuver at higher altitudes where the power density is much higher and the wind velocity is much more consistent compared to operating altitudes of conventional wind turbines. Using a realistic kite computer simulation the design of the kites can be improved, by better understanding the structural behavior of the kites. The existing kite models are able to reproduce the general behavior of the kite. However, the local effects, such as the actual shape of the structure, wrinkling, stresses and collapse are difficult topics that cannot be examined in the existing models. The models are also not able to use physical inputs and predict the behavior. In this thesis the method that is set to investigate the local effects as well as general structural behavior of the kite is the Finite Element Method (FEM). This is a predictive method, which means that the actual material properties, geometrical and external loads are used as inputs of the model. The FEM solver that is used for this research is called Madymo. This is a general purpose FEM, CFD and multi body solver and used in the automotive industry for crash investigation. The internal pressure of the LEI kite is assumed to be equally distributed inside the struts and the leading edge. In Madymo, the method that is used for this purpose is called the Uniform Pressure (UP) method. A cantilever inflatable cylindrical beam applied with a tip load is the first case study that is discussed. For validation, linear theory and an experiment are compared to a reference case of the FEM model. Also a parameter sensitivity study is performed. The second case study consists of modeling the V2 LEI Mutiny kite, including the bridle system, in FEM. The kite was qualitatively compared to a test with three load cases: gravity, load in the center of the leading edge and a falling mass. The results of the inflatable beam were very promising in the linear and first non linear states, compared to the theory. The model and theory showed a deviant behavior from the experiment, and for collapse, further study is needed. The model of the kite proved to be much stiffer compared to the real kite; however, as a first study it showed to be very promising to model the kite with FEM. Further study is needed for optimizing the model of the bridle system and to model the local effects of the kite, such as the connections between the leading edge and the struts.","","en","master thesis","","","","","","","","","Aerospace Engineering","Institute Applied Sustainable Science Engineering and Technology","","","",""
"uuid:7cea8b9a-25bb-4461-926b-de52afd339c4","http://resolver.tudelft.nl/uuid:7cea8b9a-25bb-4461-926b-de52afd339c4","System Identification with Multivariate Multiplex Splines","Visser, T.","De Visser, C.C. (mentor); Van Kampen, E. (mentor)","2014","A new type of multivariate spline, based on tensor-product splines, is introduced and applied for function approximation purposes. An algorithm for system identification using these multiplex splines is developed and validated on DelFly II flight tests data.","Multivariate Splines; DelFly; System Identification","en","master thesis","","","","","","","","2017-11-26","Aerospace Engineering","Control and Operations","","Control and Simulation","",""
"uuid:ccff9e01-522c-44da-9921-c9b92e6f753d","http://resolver.tudelft.nl/uuid:ccff9e01-522c-44da-9921-c9b92e6f753d","Experimental investigation of artificial boundary layer transition: A comparison of different tripping devices","Slangen, R.A.C.M.","van Oudheusden, B.W. (mentor); Scarano, F. (mentor); Veldhuis, L.L.M. (mentor)","2009","Nowadays there is a wide variety of applications for forced transition. They are all based on introducing disturbances to the flow and increasing its momentum thickness. Forced transition or bypass transition as it is also called is used to manipulate the flow by setting the transition point in such a way that the required/better flow situation is achieved. There is a variety of types of transition devices in use such as a simple wire, sandpaper, surface steps and zigzag tape. All of them have their own characteristics. In this report an investigation of the last two has been given. From practical experience it is known that the zigzag tape produces transition to turbulence with less height of the obstacle. This implies that the zigzag strip produces turbulence more efficiently than a two‐dimensional roughness. The difference in efficiency suggests that there may be differences in the mechanism creating turbulence behind these two kinds of devices. What happens in the transition phase of the flow over these obstacles has been investigated. For this investigation hot wire anemometry has been used to locate and quantify turbulence and particle image velocimetry to visualize structures in the flow. The results confirm the different behaviour (efficiency) of the two tripping device types. A clear difference is revealed in the flow comparing the zigzag strip to the two‐dimensional roughness element composed of a strip of rectangular cross‐section. The zigzag strip causes streamwise vortices which interact with the outer flow to create turbulence through mixing. This explains why it is more efficient. These vortices persist quite far downstream, hence the turbulent flow is only slowly moving to a uniform state. This means the flow is not completely uniform. The surface step creates a spanwise vortex which causes the mixing. This vortex doesn’t trail far behind the strip and thus creates a more homogeneous turbulent flow downstream of it.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","Aerodynamics","",""
"uuid:334727c0-694d-4ab5-926c-41cc45e476b1","http://resolver.tudelft.nl/uuid:334727c0-694d-4ab5-926c-41cc45e476b1","Effect of EGTS on airport taxi movements at AAS","Sillekens, P.J.A.","Roling, P.C. (mentor)","2015","KLM and Schiphol Group have requested an investigation into the impact of EGTS on the entire airport operations. Previous research into this technology has shown that the potential benefits for airlines, airports and society are decreased noise and emissions, fuel savings, and autonomous pushback possibilities that allow for greater versatility on the apron area. Drawbacks of the technology at this point, however, are the fact that the maximum speed of the aircraft is limited while utilizing EGTS, possibly impacting other airport traffic and even leading to taxiway congestion. Taking this problem statement as a starting point, this research is aimed at generating an impact study into the effects of EGTS on the airport operations with all the key stakeholders. In order to achieve this, the traffic situation at Schiphol airport is simulated in scenarios with and without EGTS traffic, results are compared and verified, and stakeholder discussions are subsequently held to validate the results. The main research aim is to provide Schiphol and KLM with a tangible tool that translates the concerns and interests of the main stakeholders into a value model, that can aid them in their further decision making process regarding the implementation of EGTS.","EGTS; Schiphol; KLM; impact study; value model","en","master thesis","","","","","","","","2016-04-17","Aerospace Engineering","Control & Operations","","Air Transport and Aerospace Operations","","52.30907000, 4.76338500"
"uuid:5b859467-9631-49a0-9ad9-ddd593b33e69","http://resolver.tudelft.nl/uuid:5b859467-9631-49a0-9ad9-ddd593b33e69","Changing behavior during teleoperation by tricking the brain?: Exploring a practical application of body illusions","Wajon, L.V.","Mulder, M. (mentor); Abbink, D.A. (mentor); Van Paassen, M.M. (mentor)","2015","Teleoperation is widely used in human-hostile or otherwise inaccessible environments. However, using teleoperation to perform a task is more difficult than performing the task directly. A main factor for this is limited telepresence due to the absence or distortion of natural sensory feedback. An interesting possibility to increase telepresence and enhance teleoperation performance is inducing a Body Illusion which may give human operators the sensation that the remote tool belongs to their own body. This study investigated the possibility of inducing the Projected Hand Illusion during a teleoperated reaching task, and its effects on accuracy. The participants (n=16) reached for targets while avoiding stationary obstacles, by manipulating a master device coupled to a slave device. Three conditions were randomly presented: the Direct Control (DC) condition, showing the master device with the participants' own hand, the Projected Hand Illusion (PHI) condition, showing the slave device consisting of a 3D-printed hand designed to induce a Body Illusion, and the no Projected Hand Illusion (nPHI) condition, showing the slave device consisting of a 3D-printed object of similar shape designed to not induce a Body Illusion. A questionnaire was used to assess the subjective feeling of the Projected Hand Illusion. Based on the questionnaire responses, participants were grouped in the qualifying group (n=5) or the non-qualifying group (n=11). It was found that the Projected Hand Illusion was consistently induced in both conditions, and for both groups. Also, a significant difference in distance to target in the y-direction and x-direction was found between conditions PHI and nPHI; in the nPHI condition, participants kept more distance to the obstacle than in the PHI condition. This may suggest an increased perception of risk due to a difference in visual perception or due to the Body Illusion. However, as the Body Illusion was present in both conditions according to the metric used, and the differences between conditions were found for both groups, these findings cannot be attributed to the presence of the Body Illusion with certainty. Therefore, more in-depth studies investigating the possible causes are recommended. This research shows that a Body Illusion can be evoked during teleoperation, and possibly affect its performance. Therefore, this exploratory study gives rise to further research into the practical application of Body Illusions in teleoperation.","teleoperation; task performance; telepresence; Body Illusion; Projected Hand Illusion; multisensory illusion; body ownership; psychophysics","en","master thesis","","","","","","","","2020-08-18","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:94de858f-c76e-4b95-bf13-2eb18fba0eae","http://resolver.tudelft.nl/uuid:94de858f-c76e-4b95-bf13-2eb18fba0eae","Separating Haptic Feedback and Support Signals: a Solution for Human-Machine Cooperation?","Wyzen, P.L.M.J.","van Paassen, M.M. (mentor); Abbink, D.A. (mentor)","2017","","","en","master thesis","","","","","","","","2020-01-11","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:ee2db063-a1c0-4f0c-b8a6-79f6f3acb749","http://resolver.tudelft.nl/uuid:ee2db063-a1c0-4f0c-b8a6-79f6f3acb749","The influence of laminar-turbulent transition on the perfomance of a propeller","Janssen, R.F.","Veldhuis, L.L.M. (mentor); Eitelberg, G. (mentor)","2015","The influence of laminar-turbulent transition on a propeller blade’s performance has been investigated in this study, both numerically and experimentally. The computational fluid dynamics (CFD) is performed using the TAU code developed by the German Aerospace Center, as well as an existing propeller lifting-line code. The laminar-turbulent transition is simulated using the ?-Re?t correlation based transition model, which is compared to the results of the Spalart-Allmaras one-equation turbulence model. To validate the CFD data, experiments are performed in the Open Jet Facility of Delft University of Technology, where the laminar-turbulent transition is measured using an infrared camera. The results show that at high advance ratios, the difference between the CFD simulations using the laminar-turbulent transition model and the one-equation turbulence model is large. This can be explained due to the trailing edge separation which is present in the case where laminar-turbulent transition is modeled. At lower advance ratios, the difference between the two CFD models becomes smaller. This is due to the fact that a larger portion of the flow over the blade becomes turbulent. Comparing the CFD results to the experimental results it can be seen that the location of transition predicted by the CFD simulations shows some agreement with the experimental results.","propeller; transition; performance; CFD; computational; fluid; dynamics; infrared; numerical; experimental; RANS; BEMT","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics and Wind Energy","","","",""
"uuid:e688a0be-8f75-423f-a2ad-ed68a1346bd9","http://resolver.tudelft.nl/uuid:e688a0be-8f75-423f-a2ad-ed68a1346bd9","Towards flameless combustion in gas turbine engines","van den Broek, S.A.W.","Gangoli Rao, A. (mentor); Levy, Y. (mentor)","2017","","Flameless Combustion; Jet Entrainment; Air and Fuel inlet; Recirculation zone","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Flight performance and Propulsion","",""
"uuid:4f911816-82e9-4dc0-8ed0-42f2fb552fb4","http://resolver.tudelft.nl/uuid:4f911816-82e9-4dc0-8ed0-42f2fb552fb4","Tanker allocation optimization during civil air-to-air refuelling operations","Brugmans, W.F.J.P.","Visser, H.G. (mentor)","2017","","operations research; air-to-air refuelling; set-partitioning; tanker routing; tanker scheduling","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:65ca3c12-21f2-462b-b655-e6a88c537651","http://resolver.tudelft.nl/uuid:65ca3c12-21f2-462b-b655-e6a88c537651","Predicting the rooftop wind climate for urban wind energy in the Rotterdam - Delft - Zoetermeer region: New approaches for implementing urban height data in the wind atlas method","van Wijk, B.M.","van Bussel, G.J.W. (mentor); Bierbooms, W.A.A.M. (mentor)","2011","","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","Sustainable Energy Technology","",""
"uuid:1fc3ce20-29c4-4895-bf7d-fd66a19b25e1","http://resolver.tudelft.nl/uuid:1fc3ce20-29c4-4895-bf7d-fd66a19b25e1","Database driven forecasting of spare parts demand at the Royal Netherlands Airforce","Schraven, M.","Verhagen, W.J.C. (mentor)","2015","The Royal Netherlands air force (RNLAF) has been coping with a low availability of F-16 aircraft. It has been acknowledged that increasing the availability of avionics components is most beneficial to increasing fleet availability. Especially for F-16, rich database information is available including past operations and maintenance dating back to 1996. Improving the methods which are used to forecast the demand of avionics components is an important precondition to decrease multiple lead times in the F-16 supply chain. The readily available database information should be used to this goal. The research objective of this research project is hence as follows: Develop a novel spare parts demand forecasting method in order to increase F-16 avionics component availability by (1) evaluating state-of-the-art spare parts demand forecasting methods with the RNLAF time series demand data and (2) applying RNLAF data of component technical characteristics and component operational exposure in conjunction with the original historical demand data to improve selected method(s) Academic literature clearly stipulates that the methods of Croston, Syntetos, Babai and Teunter should be used to forecast intermittent demand. However, no literature has been found on how to improve these demand history based methods by using other data inputs like maintenance and operational history. Also, only limited literature was found about the extraction of demand drivers from databases. In short: A research opportunity is present. The developed conceptual model consists of five parts: Input (of demand, maintenance and operations data), steering variable (SV) generator, forecast method applier, stock level simulator and error minimizer. It is expected that stock level performance for avionics parts can be improved by (1) selecting the optimal forecast method, (2) selecting the optimal smoothing constants, (3) applying an SV deducted from installed base and/or FHRS per month variables. First, an optimal method and settings are established “in sample”. This ‘best fit’ is subsequently tested “out of sample” and compared to RNLAF stock levels to validate its performance. The installed base and FHRS per month variables are computed by combining two datasets and establishing install-removal intervals for a set of 110 unique components. The variables are translated into normalized and smoothed variables which are used to momentarily damp or gain the next estimate of the selected forecast method. Both installed base and FHRS per month variables are related to the utilization of components. An increase/decrease of the installed base (the total amount of installed components of a specific type at a specific time) or FHRS in a specific month for a component is expected to result in more/less defects of and hence demand for that component. A forecast optimization tool is built to implement the conceptual model. Enabling ease of experimentation by including many adjustable parameters and visualizing outputs to gain insights was of high priority throughout the development. The tool is capable of optimizing forecast methods and settings for all component demand inputs (110) in batch mode. The main output of the tool is exported in spreadsheet format. Analysis of the output of the forecast optimization tool resulted in the general conclusion that forecasting performance of the included forecast methods can be increased by using maintenance and operational data of the components, but the overall performance gain is small. In specific: SV information is used to generate better “in sample” forecast fits for approximately 50% of the components demand forecasts for which installed base information was available. In those cases, the mean performance gain in relation to the conventional forecast mode is 17.7% for installed base SV mode and 12.4% for FHRS SV mode. For aperiod of six months out of sample, a percentage of 50.0% of the optimized installed base SV forecasts and 47.9% of the optimized FHRS SV forecasts still perform best and are therefore robust for the demand pattern of the specific components. The out of sample robust SV powered forecasts lead to performance gain for 20.9% of the components. The mean performance gains are 47.7% and 21.3% for installed base SV and FHRS SV modes respectively. The research project succeeded in the development of a model and method for forecast optimization using multiple sources of information in parallel to demand history. The research project addressed two novel aspects not yet covered in academic literature: (1) Batch optimization of the choice for a forecasting method and parameter settings in relation to the specific demand patterns. (2) Operationalize multiple predictive variables from maintenance and operations databases and integrate them in the forecasting method. The provided platform is not perfect but will confidently serve as a starting point for further innovative research.","forecasting; spare parts; data mining; demand drivers","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Air Transport & Operations","",""
"uuid:245b8941-08f3-4322-a442-d50e174e3c05","http://resolver.tudelft.nl/uuid:245b8941-08f3-4322-a442-d50e174e3c05","Determination of the attitude state of space debris objects based on Satellite Laser Ranging, using Envisat as a test case","Lagaune, B.F.","Doornbos, E.N. (mentor)","2016","The attitude state of the passive Envisat satellite (ESA) has been estimated before using various techniques like Satellite Laser Ranging, radar and using light-curves. This research focusses on the use of Satellite Laser Ranging. Due to the relatively large (meter scale) offset between the center-of-mass of the satellite and the reflector where the laser signal is reflected back to the transmitting and receiving ground station, large oscillations in the range residuals are visible. These oscillations show the rotating behaviour of Envisat, and can be translated to its rotational state by re-producing this signal using a corresponding attitudemodel and the offset between the reflector and the center-of-mass. First a purely theoretical case was considered where a known simulated orbit and attitude where estimated for various cases in order to validate the use of the estimation scheme. Afterwords, the real Satellite Laser Ranging data of Envisat was used for the time period 2013-2015.","SLR; attitude; estimation; determination; Envisat; space debris; simulation; GEODYN; tumbling","en","master thesis","","","","","","","","2016-12-21","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:50160767-a111-439c-9996-d24fe20c14bc","http://resolver.tudelft.nl/uuid:50160767-a111-439c-9996-d24fe20c14bc","Formation Flying in the Sun-Earth/Moon Perturbed Restricted Three-Body Problem","Out, I.A.","Van den Ijssel, J.A.A. (mentor); Visser, P.N.A.M. (mentor); Zandbergen, B.T.C. (mentor)","2017","","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:60735006-580b-4448-a6d2-7bcfa6e283e1","http://resolver.tudelft.nl/uuid:60735006-580b-4448-a6d2-7bcfa6e283e1","Characteristics of flow through orifices in pipes: An experimental investigation","Anantharaman, V.","Van Oudheusden, B.W. (mentor)","2014","Orifice plates are key components used for flow measurement and control in several industries. For instance, they find applications in gas and liquid circuits of lithography machines, nuclear power plants and aerospace propulsion systems. They are used typically either for measuring flow-rate or to introduce a pressure drop for purposes of flow balancing. The present study focuses on the latter application. It is widely acknowledged in literature, that the turbulent, unsteady nature of the flow issuing through an orifice can also be a source of structural vibration. In order to understand the nature of the vibration source, the present experimental investigations analyze the time-varying flow field by means of unsteady wall-pressure measurements and time resolved, planar, particle-image-velocimetry (PIV). In addition to understanding the dynamics of the flow through a single-hole orifice, this study has assessed the possibility of using multiple-hole orifices as an alternative. It is observed that the overall magnitude and extent of the disturbance levels in the flow are reduced with the multiple-hole orifices, while maintaining similar levels of pressure drop. It is hypothesized that these lower disturbances are a result of the small-scale flow structures associated with the multiple-hole orifice flow (multiple jets as opposed to one). The measurements give detailed insights into the flow behavior downstream of orifice plates. Results indicate a low frequency flapping motion of the single-hole orifice jet, which is sustained by the surrounding large recirculation regions. For the geometries of the sharp-edged single-hole orifices investigated, the flapping frequency was observed to increase with flow speed and is found to occur at a Strouhal number = 0.02 based on the orifice jet velocity and the difference in internal diameters of the pipe and orifice.","single hole orifice; multiple hole orifice; particle image velocimetry; flow induced vibrations; proper orthogonal decomposition; pressure drop; pressure fluctuations","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics","","","",""
"uuid:5f8a549a-443b-40aa-b928-3c2e205526b0","http://resolver.tudelft.nl/uuid:5f8a549a-443b-40aa-b928-3c2e205526b0","Design Optimization for Enhanced Fuel Mixing and Reduced Combustion Instability: Enhancing Swirler Performance of a Small Turbojet Engine Combustor","Venter, P.","Visser, W. (mentor)","2015","Aero-engine performance is becoming an increasingly regulated aspect in aerospace indus- tries with tighter restrictions on emissions, greater expectations for efficiency and thrust as well as broader requirements for the range of the operating flight envelope. With an increasing consciousness toward these factors during the design of combustors, research led development and improvement of every single aspect of the combustor design needs to be considered in this modern era of aerospace technology. A major contributor to such performance enhancement is the design of flow swirlers used to induce central re- circulation zones in the primary fuel/air mixing region. In the current study, the effect of modification to a swirler’s vane blade angle on mixing effectiveness and combustion stability is investigated, using flow properties such as turbulent kinetic energy, fuel dis- tribution and pressure losses as a measure of combustor performance. The study takes a sensitivity analysis approach and makes use of an existing combustor design that acts as a benchmark for verification of results. A cold flow computational fluid dynamics anal- ysis is used to test the effect of blade angle modifications based on a ‘cause and effect’ methodology. The computational fluid dynamics model is validated against experimental data from a similar combustor. It was found that optimal fuel/air mixing occured in a 70? blade angle swirler however large pressure losses and excessive vortex shedding directly behind the center body indicated a strong likelihood of combustion instability. Good fuel atomisation through strong shear layers and excellent pressure recovery seen in a 30? blade angle swirler was accompanied by poor fuel/air mixing. A swirler design featuring 50? blade angles was found to be the optimum, with good fuel atomisation, stable recir- culation zones, promising flame anchoring potential, dispersive but orderly homogenous fuel/air mixing and desireable pressure recovery characteristics.","swirler; combustion stability; fuel mixing; CFD; cold flow; Optimisation; K ? ?; turbulence model; vortex; recirculation","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","Flight Performance and Propulsion","",""
"uuid:198390b8-b81f-4a13-9c80-15befd3c0428","http://resolver.tudelft.nl/uuid:198390b8-b81f-4a13-9c80-15befd3c0428","The Unified State Model. Derivation and Applications in Astrodynamics and Navigation.","Vittaldev, V.","Mooij, E. (mentor); Naeije, M.C. (mentor)","2010","","Astrodynamics","en","master thesis","","","","","","","","2010-12-31","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:a1599dd3-8fa0-42fa-acc8-be9deaabaadb","http://resolver.tudelft.nl/uuid:a1599dd3-8fa0-42fa-acc8-be9deaabaadb","Maintenance of a Long Baseline Along-Track Formation for the DelFFI Mission","Deep, A.","Guo, J. (mentor)","2015","","","en","master thesis","","","","","","","","","Aerospace Engineering","Space Systems Engineering","","","",""
"uuid:64ad2b3d-2628-4720-94ec-d07af131ed47","http://resolver.tudelft.nl/uuid:64ad2b3d-2628-4720-94ec-d07af131ed47","Certification for Small Urban Wind Turbines: Verification of tlie lEC 61400-2 design methodology for a small wind turbine operating in the built environment","Chaves dos Santos, N.P.","van Bussel, G.J.W. (mentor); van Sark, W. (mentor); Simao Ferreira, C.J. (mentor)","2009","Microgeneration is a growing type of energy conversion used for generation of electricity in built environments such as urban areas. Among the different microgeneration technologies present in the market, small wind turbines have been showing a significant growth. The significant dissemination of its use and production and safety issues that arise from its deployment in urban areas have led to concerns in the insurance of its correct and safe design. Therefore the certification of the design process of these turbines is seen as an essential aspect to preserve this growing wind market worldwide. Currently, the design certification for Small Wind Turbines is set by the International Electrotechnical Commission in its lEC 61400-2 Ed.2 standard. It was considered that the present standard resulted from an adaptation and simplification of the lEC 61400-1 standard (used for the design large wind turbines), not considering some specific aspects typical of small wind turbines, nor the specific conditions of built environment wind conditions. The lEC 61400-2 standard introduces a methodology for load calculations based on a simplified load model by application of some simple equations. In order to validate this method for a small wind turbine operating in built environment wind conditions, aeroelastic modeling was used. Using real wind data obtained measured at an urban site (top of the Aerospace Engineering building), the loading on a 1.94 m rotor diameter turbine was analyzed by used of NWTC's FAST code. It was proven that the simplified load model underpredicted the loads for the maximum thrust load case. It was also proven that for the load case for Yawing, the simplified load model underpredicted the loading at yaw rates lower than the prescribed maximum. It was also proven that the high turbulence, typical of built environment wind conditions, generated higher loads than the ones predicted by the standard. Still, these results were considered complaint with the standard due to the large safety factor set for this load calculation methodology. However, these safety factors were considered to be not too informative or precise, limiting the validity of the simplified load model as a good load calculation method for the safe design of a small wind turbine.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:63a08d3d-722d-4a66-a7ef-37effdace320","http://resolver.tudelft.nl/uuid:63a08d3d-722d-4a66-a7ef-37effdace320","Aerodynamic Performance Study on Ducted Propeller System for Propulsion and Control & Stability Applications","Harinarain, V.N.","Vos, R. (mentor)","2017","The Delft University Unconventional Concept (DUUC) is an innovative short take-off medium range aircraft design that utilizes a system of two ducted propellers, mounted on the aft part of the fuselage. The first design of this system consists of two axisymmetric ducts, each containing a propeller mounted to a centerbody that is attached to the duct by a strut. Furthermore each ducted propeller contains two horizontal and two vertical control surfaces and the ducted propellers are mounted to the fuselage by two external struts. Besides the function of propulsion, the ducted propeller system also replaces the horizontal and vertical tail for control and stability. The aerodynamic characteristics of this system are investigated by the construction of an aerodynamic performance model, consisting of a combination of low order analytical and numerical methods. This model aims on predicting the aerodynamic coefficients, which are significant for control and stability over a range of operational conditions, incidence angles and thrust settings. These include lift, side force, drag and control surface effectiveness. The numerical part of the model is first validated against existing experimental data from literature, after which the complete model is held against data from a low speed wind tunnel test on a small scale model of the system. Finally, a sensitivity analysis aims on finding the effect of the most important design parameters on the thrust to power ratio of both the propeller and the total system. The numerical model is succesfully validated in its capability of predicting trends in propeller and total system thrust over a range of operational conditions. The analytical model is capable of predicting the lift and side force performance of the system to a reasonable degree in the unstalled regime. Drag is significantly underestimated by the analytical model, possibly due to unknown flow separation and interference effects, which require higher order methods. Stall angle and maximum lift can not be modeled accurately by the low order performance model. Finally, the sensitivity analysis shows that advance ratio is the most critical operational condition whereas duct shape and duct aspect ratio are most affecting the total system thrust to power ratio.","","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance & Propulsion","","","",""
"uuid:3b1c6432-cfbf-4fec-894b-9f6b870015f5","http://resolver.tudelft.nl/uuid:3b1c6432-cfbf-4fec-894b-9f6b870015f5","Wing Shape Multidisciplinary Design Optimization","Mariens, J.","Elham, A. (mentor)","2012","Multidisciplinary design optimizations have shown great benefits for aerospace applications in the past. Especially in the last decades with the advent of high speed computing. Still computational time limits the desire for models with high level of fidelity cannot be always fulfilled. As a conse- quence, fidelity is often sacrificed in order to keep the computing time of the optimization within limits. There is always a compromise required to select proper tools for an optimization problem. In this final thesis work, the differences between existing weight modeling techniques are investi- gated. Secondly, the results of using different weight modeling techniques in multidisciplinary design optimization of aircraft wings is compared. The aircraft maximum take-off weight was selected as the objective function. The wing configuration of a generic turboprop and turbofan passenger aircraft were considered for these optimizations. This should aid future studies of wing shapes in early design stages to select a proper weight prediction technique for a given case. A quasi-three- dimensional aerodynamic solver was developed to calculate the wing aerodynamic characteristics. Various statistical prediction methods (low level of fidelity) and a quasi-analytical method (medium level of fidelity) are used to estimate the structural wing weight. Furthermore, the optimal wing shape was found using a local optimization algorithm and is compared to the results found using a novel optimization algorithm to find the global optimum. The quasi-three-dimensional aerodynamic solver was validated using experimental data and other available aerodynamic tools. Compared to the results generated by other tools, the developed solver has a wider range of validity. Most important of all, it is up to 10 times faster and the results show good agreement with other data. Several test cases were used to prove the robustness and effectiveness of the global optimization algorithm. A comparison of the different weight estimation methods indicated that the lower level fidelity methods are insensitive for some wing parameters. The results of the optimizations showed that the optimum wing shape is affected by the used weight modeling technique. Use of different weight prediction methods strongly affects the computational times and the convergence history. The global optimization algorithm was able to find the global solution for the wing shape optimization. However, the search for the global optimum comes at a cost: the computational time is significantly larger.","wing; shape; optimization; quasi-3D; multidisciplinary; MDO; locsmooth; wing weight prediction; EMWET","en","master thesis","","","","","","","","2012-08-31","Aerospace Engineering","Flight Performance and Propulsion","","Aircraft Design","",""
"uuid:0c143537-0bce-4599-bb3a-9095a044cb1a","http://resolver.tudelft.nl/uuid:0c143537-0bce-4599-bb3a-9095a044cb1a","Experimental study on the energy deposition of an ns-DBD plasma actuator and its effect on a laminar boundary layer","Winkel, R.","Correale, G. (mentor); Kotsonis, M. (mentor); Winkel, R. (mentor)","2015","An experimental study aimed at the influence of different barrier materials on the energy deposition of nanosecond pulsed dielectric barrier discharge (ns-DBD) plasma actuator was carried out. Additionally, the direct effect of the discharge of an ns-DBD plasma actuator on a low velocity laminar boundary layer was investigated. Three barrier materials were selected for this study. These were Kapton polyimide tape, silicone-rubber and fine polyamide PA2200. Schlieren imagery in quiescent conditions were conducted to visualize the effect of the thermal energy deposition. Particle Image Velocimitry (PIV) was used to obtain the induced velocity fields by a flush mounted ns-DBD plasma actuator with a two layer Kapton barrier in a laminar boundary layer. A backward-time backward-space finite difference discretization of the compressible continuity equation was proposed to quantify the density field disturbance by ns-DBD plasma actuator. Results of the barrier characterization study indicated that a thinner barrier of the same material will allow more thermal energy to be deposited to the air per discharge pulse. A comparison between disturbed density field area and electrical energy usage per pulse, showed that an ns-DBD plasma actuator with a Kapton barrier is the most efficient tested barrier for coupling electrical energy as thermal energy to the near wall volume of air. Additionally, both the structure of the density disturbance in the quiescent air and the plasma discharge structure itself (Figure 1) are strongly dependent on the barrier material. Results of the PIV tests on the effect of discharge by ns-DBD plasma actuator in a laminar boundary layer indicated the presence of small body force. This body force was directed from the grounded exposed electrode to the high voltage covered electrode. Moreover, this body force induced a vortex like disturbance in the boundary layer. Additionally, independent of the streamwise orientation of the ns-DBD plasma actuator electrodes, an increase in energy input results in a local decrease in density. A larger area of density field disturbance was observed for the results were the body force was directed opposite to the freestream flow. It can be concluded that a barrier used in an ns-DBD plasma actuator should have a low thickness, high electrical volume resistivity, low thermal capacitance and low heat capacity in order to efficiently deposit heat to the nearby air. Additionally, based on the density field disturbances in laminar boundary layer flow, the orientation of the ns-DBD plasma actuator (thus the direction of the body force) is able to enhance the impact of the thermal energy deposition through better distribution through the boundary layer.","thermal energy deposition; ns-DBD; plasma actuators; PIV; Schlieren","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics and Wind energy","","Aerodynamics","",""
"uuid:e32f84f1-21da-4a5a-a541-2f15b041ede5","http://resolver.tudelft.nl/uuid:e32f84f1-21da-4a5a-a541-2f15b041ede5","Sensitivity of Pusher Propeller Performance and Noise Emissions to the UpstreamWake Characteristics: An Experimental and Numerical Study","Channa, V.V.","Sinnige, T. (mentor); Veldhuis, L.L.M. (mentor)","2015","Open rotors are considered to have the potential to improve the fuel economy of aircraft significantly by improving the propulsive efficiency compared to the current generation turbofan engines. One of the possible configurations for the open rotors is the aft fuselage mounted contra-rotating pusher propeller. The aftfuselage mounted contra-rotating pusher propeller offers significant benefits in terms of interior noise and ground clearance compared to the wing mounted propeller aircraft. However, the pusher configuration is subjected to a non-uniform inflow due to the upstream pylon wake which affects the aerodynamic performance and noise emissions of the propeller. The objective of this research is to analyse the sensitivity of the pusher propeller performance and noise emissions to the upstream pylon wake characteristics by both experiments and numerical computations. The experiments are conducted at Delft University of Technology. To validate the experiments, a numerical model was developed using an existing propeller lifting line code coupled with an analytical model to estimate the effect of pylon wake on pusher propeller performance and noise emissions. The pylon wake velocity measurements in the freestream direction are affected by the presence of the downstream propeller. With a decrease in advance ratio, the negative pressure gradient upstream of the propeller decreases the non-dimensional wake displacement thickness and the non-dimensional wake velocity deficit. The wake profiles measured at zero thrust condition and computed numerically are in good agreement, with differences in velocity deficit of the order of 2%. The propeller performance results indicated that the rotating shaft balance used could not measure the pylon installation effect accurately. The measured offset in propeller performance is attributed to an error in measurement. Within the limitation of the accuracy of RSB, the propeller performance measurements for different pylon-propeller spacings remained constant. Numerical computations are also performed to evaluate the effect of the pylon wake on the propeller performance. The effect of installation increases with increase in advance ratio. The experimental noise measurements indicated an increase in sound pressure levels with the installation of pylon. The effect of installation is seen as tones at blade passage frequency. The Flyover directivity pattern indicated an increase in sound pressure level at all flyover angles measured. The increase in sound pressure level due to the installation of pylon is prominent both upstream and downstream of the propeller due to the low sound pressure level observed for the isolated configuration. Numerical evaluations showed that the computed sound pressure levels are underpredicted for the isolated configuration at low freestream velocities which is due to the decrease in radiation efficiency at low freestream velocity. The sound pressure level for the pylon-installed configuration computed showed an increase across all the flyover angles. From the experimental and numerical investigations performed, the effect of installation on the propeller performance is negligible whereas the effect on the propeller noise emissions is significant. This result is of significance as it can be used as an advantage in the design of the pusher propeller.","propeller; performance; acoustics","en","master thesis","","","","","","","","","Aerospace Engineering","Flight propulsion and performance","","Flight propulsion and performance","",""
"uuid:0ecbcb74-47aa-4a36-8c53-165c4a20433a","http://resolver.tudelft.nl/uuid:0ecbcb74-47aa-4a36-8c53-165c4a20433a","Time dependent flow simulations using the least-squares spectral element method: Application to unsteady incompressible Navier-Stokes flows","Kwakkel, M.","Koren, B. (mentor)","2007","The least-squares spectral element method (LSQSEM) combines the flexibility of the finite element method (FEM) with the accuracy of the spectral element method (SEM) and the efficiency of the least-squares (LSQ) formulation. Recently the method has been applied to steady flows and unsteady flow with a space-time formulation. In a space-time formulation space and time are treated in an uniform way, which leads to a high accuracy in both space and time. The downside of the formulation is however a larger system of equations, which increases the computational time. In this work two space-time methods are compared with four time-stepping methods. To verify the different methods, they are all tested on the one-dimensional and twodimensional linear advection equations for various initial conditions. For these problems the exact solution is known, so the error of the methods can be determined and compared.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4edc7f3d-3aa6-44f7-b6f9-893bc3b84e4b","http://resolver.tudelft.nl/uuid:4edc7f3d-3aa6-44f7-b6f9-893bc3b84e4b","Wake Vortex Encounter Analysis with Different Wake Vortex Models Using Vortex-Lattice Method: A numerical study","Liu, C.","Bijl, H. (mentor)","2007","The steady increase in air traffic creates a need for an increase in airport capacity. To achieve this we need to safely reduce existing separation standards. An important limiting factor in establishing required separation standards is the risk imposed by wake vortices. To determine the risk, the induced rolling moment plays a dominant role in safety analysis. The objective of the present study is to programme a reliable MathCADTM code based on the Vortex Lattice Method (VLM) to calculate the induced rolling moment on an aircraft during wake vortex encounters (WVEs). The code is named Chaos, because of the complexity of WVEs.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:79a6fc75-2851-4732-973b-44e09335e203","http://resolver.tudelft.nl/uuid:79a6fc75-2851-4732-973b-44e09335e203","Active Flow Control Using Plasma Actuators Application on Wind Turbines","Dialoupis, Athanasios","van Bussel, G.J.W. (mentor); Kotsonis, M. (mentor); Pereira, R.B.D.S. (mentor)","2014","","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","Sustainable Energy Technology","",""
"uuid:7faf08f7-d16f-4836-b4ff-61ea060bd166","http://resolver.tudelft.nl/uuid:7faf08f7-d16f-4836-b4ff-61ea060bd166","Modelling the Propeller Slipstream Effect on the Longitudinal Stability and Control","Bouquet, T.","Roelof, V. (mentor); Veldhuis, L.L.M. (mentor)","2016","As the aviation industry continues to strive for improvements in fuel efficiency throughout the entire aircraft design, interest has been renewed in propeller engines. New research into advanced turboprop engines, so-called open rotor engines, seems promising as they combine the inherent high propulsive efficiency of ordinary turboprop engines, with the capability of delivering higher thrust. Unfortunately, the implementation of propeller engines does have significant implications on the stability and controllability of an aircraft. These implications are primarily caused by the propeller slipstream, the complex streamtube behind the propeller with strong gradients in various flow quantities both in streamwise and radial direction. The objective of this thesis was to develop, implement, and validate a prediction method for the propeller slipstream effect on the longitudinal stability and control of conventional aircraft configurations in the Initiator. During the investigation of the propeller slipstream effect, an existing prediction method was found which was based on calculating the four major effects caused by the propeller slipstream on the longitudinal stability and control. These four effects are, an additional normal force at the propeller disk, an increase in lift over the wing due to the slipstream, a change in the tail-off pitching moment, and a change in tail contribution to the pitching moment due to increased downwash and dynamic pressure. This method seemed ideal as it not only gives relatively accurate results, but does so with computationaly inexpensive calculations. During the implementation of this method in the Initiator, additional changes were made to calculate aerodynamic variables which were previously estimated using an extended vortex lattice method program. This implemented prediction method was validated using the only available wind tunnel data for the Fokker 50 and a special Saab 340 with T-tail configuration. Through this validation, the prediction method proved to maintain an acceptable accuracy for all configurations with minimal computation time. Further analysis of the results showed that the propeller slipstream effect reduces the tail effectiveness due to an increase in downwash angle at the tail. This was especially the case for the Fokker 50, which due to its low wing configuration, has a further increase in downwash caused by an inflow effect of the outer flow into the streamtube.","aircraft design; initiator; propeller slipstream; longitudinal stability and control","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","Flight Performance and Propulsion","",""
"uuid:6dcf763e-a5c7-4dc6-a925-515405825eb9","http://resolver.tudelft.nl/uuid:6dcf763e-a5c7-4dc6-a925-515405825eb9","Eddy Current braking applied to the Kosmos-3M second rocket stage","Michielsen, M.","Cowan, K. (mentor); Noomen, R. (mentor)","2016","","","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","Spaceflight / Space Exploration","",""
"uuid:ecacd9e7-7ed7-4fb3-89c8-e3077d02b2d4","http://resolver.tudelft.nl/uuid:ecacd9e7-7ed7-4fb3-89c8-e3077d02b2d4","Coarse grid correction for partitioned fluid-structure interaction problems","Bosscher, S.","Koren, B. (mentor)","2005","The use of more flexible structures in aircraft offers considerable potential for more efficient aircraft, but increased exibility makes aircraft structures more susceptible to destructive interactions with the air ow around them. Numerical simulations are necessary to predict the behavior of these interactions so that aircraft designers can avoid destructive fluid-structure interactions (FSI). One possible way to simulate FSI is by coupling existing Computational Fluid Dynamics (CFD) and Computational Structural Mechanics (CSM) solvers. Two improved algorithms were developed to couple existing CFD and CSM solvers using a coarse grid correction and high-order Additive Runge-Kutta (ARK) time integration schemes. The new algorithms reduce the partitioning error by computing accurate predictions for the coupling terms on coarse grids. Both coarse grid corrections and ARK schemes have previously been used in CFD and CSM, but their combined application to FSI simulation is new. It was demonstrated for an FSI test problem that the new algorithms may reduce the amount of work to obtain levels of accuracy acceptable for engineering by an order of magnitude. Future work will include extending the newly developed algorithms to nonlinear problems and implementing them in new FSI solvers.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:62b081a4-f3c6-42d2-b3be-ab82563778db","http://resolver.tudelft.nl/uuid:62b081a4-f3c6-42d2-b3be-ab82563778db","Assessing noise level variability in fly-over data","Vander Eyken, S.","Snellen, M. (mentor)","2016","As the air travel industry steadily grows, so does the noise pollution that comes with it. This brings with it a myriad of socio-economic consequences, especially in the vicinity of airports. In order to combat this aircraft noise at its origin, it is important to know where it originates from and determine the prevalent sound sources on an aircraft and their contribution to the noise. The goal of this research is to determine the different aircraft noise sources in fly-over data collected by a microphone array during landing. In addition to locating the prevalent noise sources, also the variability is assessed. Subsequently it is investigated to what extent the engine settings and aircraft velocity affect the sound levels of the noise produced by these sources. The data used to accomplish this goal was collected from 115 fly-overs at Schiphol Airport on two separate measurement days, using an acoustic array with 32 microphones that was developed at the faculty of Aerospace Engineering. Of these measurements, 43 Boeing 737 “Next Generation” fly-over measurements were selected for analysis. Using beamforming, the locations of different sound sources and their corresponding sound pressure levels were determined. After defining different sound signals from the fly-over data, using conventional delay-and-sum beamforming on these signals, various noise sources at the engines and a noise source at the wings were located. The correlation of these noise sources sound pressure level with the engine setting and velocity was also investigated. This helped to further determine the origin of the noise.","aircraft noise; beamforming; noise variability","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Aircraft Noise and Climate Effects (ANCE)","",""
"uuid:6f66cd83-673c-4a20-ae5f-c3ea1b7ce3c3","http://resolver.tudelft.nl/uuid:6f66cd83-673c-4a20-ae5f-c3ea1b7ce3c3","Conceptual Design of Blended Wing Body Airliners Within a Semi-automated Design Framework","Brown, M.T.H.","Vos, R. (mentor)","2017","Blended wing body aircraft represent a paradigm shift in jet transport aircraft design. Stepping away from the conventional tube-and-wing philosophy, they promise benefits over existing or future conventional aircraft. The most significant challenge with the concept is the increased coupling between aircraft design disciplines that has necessitated the development and implementation of multidisciplinary design optimisation routines. A novel conceptual aircraft design program named the Initiator has been developed that is able to design conventional and unconventional passenger transport aircraft, enabling comparisons to be made which are based on the same top level requirements and analysis fidelity. It however lacks the ability to design or analyse the blended wing body. The aim of this thesis is to make comparative studies between the blended-wing-body aircraft and its conventional tube-and-wing counterpart based upon the same design requirements. To this end the work investigates the methods that are required to implement the blended wing body aircraft in a semi-automated design framework such as the Initiator. By developing a novel geometric parametrisation of the blended wing body, the design possibilities have been increased while maintaining straightforward shaping manipulation and robustness. All relevant topics of conceptual aircraft layout are considered, making the resulting aircraft feasible in terms of the integration of its components. Furthermore, methods have been implemented or developed which are capable of analysing the mass, aerodynamic performance and longitudinal stability of the aircraft to a fidelity which is suitable for conceptual design. The mass estimation methods that have been implemented are verified and validated to be within 10% of reference blended wing bodies with a smaller error of 5% being common. There is however significant scatter in reference results, making conclusive statements about accuracy difficult. Drag estimations perform less accurately with drag being overpredicted by approximately 20%. The cause of this over prediction was largely due to empirical corrections for miscellaneous and unaccounted drag sources as is done for conventional aircraft. Wave drag is considerably higher than reference cases (7 versus 1 counts). Considering the applicability of the implemented method to blended wing bodies and the limited specific transonic design that is performed, it is chosen to accept this result as a conservative estimate until higher order validations of the wave drag can be performed. Induced drag was also higher for the test cases but results are inconclusive whether this is an error or a true result of the design choices. Zero-lift drag has however been accurately estimated by the novel implementation of empirical methods. Test case blended wing body and tube and wing aircraft were formed in the 150, 250 and 400 passenger classes. The comparisons of the resulting aircraft show that the blended wing body is feasible at the fidelity level achieved. They have reduced mass, improved aerodynamic efficiency and higher fuel economy. Trends show that the improvements over tube and wing aircraft increase with aircraft size. The qualitative results contained herein should still be treated as provisional since the implementation of the concept is not complete and remaining topics could still have significant effects on the results.","Blended Wing Body; BWB; Hybrid Wing Body; HWB; conceptual; design; MDO; KBE; unconventional; passenger; aircraft; oval fuselage","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Flight Performance and Propulsion","",""
"uuid:a554505a-21a9-4cc4-8b5e-34da84e1fed8","http://resolver.tudelft.nl/uuid:a554505a-21a9-4cc4-8b5e-34da84e1fed8","Convex Guidance for Envisat Rendezvous","Bhagat, M.","Mooij, E. (mentor)","2016","This thesis is focused on autonomous trajectory planning for Active Debris Removal (ADR), commencing from far-range rendezvous and up to a point just before docking. Unlike typical rendezvous missions, the target in ADR is not designed for rendezvous and capture; it is usually uncooperative and possibly tumbling. If the satellite is unpassivated, then there is the added risk of explosion, while the presence of large appendages can make the satellite fragile. A case in point is Envisat, European Space Agency's largest satellite (about 8000 kg) that went defunct in 2012 and is currently, their prime concern for ADR. Most past and current technology for guidance is based on the Clohessy-Wiltshire (CW) equations, which are limited in terms of application - they use linearized dynamics, need circular orbits, employ impulsive burns, and require the user to provide some initial guess for the solution. Realistic final approach involves a number of trajectory constraints, like those on docking axis alignment, approach cone angle, keep-out-sphere, station-keeping and hold points, which are hard to include with CW-equations. Further, there is a need to make the system autonomous so that it can handle off-nominal situations as well. Convex optimization problems are a class of problems that are nearly as easy to solve as linear problems, but are more general in their scope of application. They can handle some non-linear constraints, be solved in polynomial time and are guaranteed to give global minimum. Inspired from the recent development of convex-optimization based trajectory-planning technique by Liu (Autonomous trajectory planning by convex optimization, PhD thesis, Iowa State University, 2013), a guidance algorithm is developed for the Envisat mission. In comparision with Liu's algorithm, it shows faster convergence (upto 5 times faster), improved accuracy (by an order of 2), and low computational cost (upto 40% in specific cases). Additionally, a method to automate the problem formulation in conic form is provided, so interfacing software can be skipped and the problem can be solved upto 9 times quicker. The guidance algorithm is able to handle all constraints of the Envisat mission, with the exception of forced motion constraint inside the keep-out-sphere. An alternative formulation is suggested which is moderately successful. The algorithm is also able to generate solutions for various attitude scenarios of Envisat. However, it is found that the method is not reliable, as some times feasible problems are found to be infeasible, or the solution is over/under estimated. Also, despite the improvement in accuracy, it still deviates substantially from the computed path, and needs a path-tracking mechanism. A PID controller is found to be sufficient for this purpose. A novel work-around to include perturbations was successfully demonstrated as well. To summarize, although the convex-optimization based guidance method has very specific advantages over CW-equations, there is a lot left to be improved with respect to robustness and autonomy.","","en","master thesis","","","","","","","","","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:43da6232-92af-4e27-a011-0c43c3677255","http://resolver.tudelft.nl/uuid:43da6232-92af-4e27-a011-0c43c3677255","Effects on support structure design due to wake-generated turbulence","Guzman Tejada, Russell A.","Zaaijer, M.B. (mentor)","2014","As the world demands cleaner, sustainable and economical energy sources, the wind energy academia and industry battles to increase performance and reduce costs. One of the promising fields of study is wind turbine wakes in wind farms. The position of the turbines within the layout affects the intensity of their wake effects, such as reduced wind speed or turbulence, therefore the choice of its position has an impact on wake losses and fatigue damage induced by wake-generated turbulence on the components. In this work, the possibility of wind turbine’s support structure cost reduction is explored by studying the effect on its design (and cost) caused by wake-generated turbulence. Furthermore, layout optimization considering wake losses and the wake-affected support structure cost was studied. To obtain insights about these effects, the turbulence intensity calculation and a simple support structure design were implemented into the wind farm design tool TeamPlay (by M. Zaaijer in the Wind Energy Research Group at TU Delft) and used to perform a series of case studies. The turbulence calculation was implemented following the IEC guidelines for any layout and wind direction distribution. The simple support structure design approach used in this work is based on two key aspects: (1) a base design obtained from Teamplay which does not account for fatigue and (2) the assumption of proportionality between fatigue equivalent load and turbulence. By using these tools, a location-specific support structure design within the wind farm was performed. Further, the weight and cost of the support structures was compared with the case in which all support structures have the same design obtained from the worst turbulence regime. It was found that wake-induced fatigue and its effect on the support structure design is not relevant for layout-spacing optimization because wake losses dominate the cost changes due to layout changes. Moreover, it was found that location-specific support structure design, according to their specific turbulence regime, would result in cost reductions that could account, as an upper limit, between 0.3 % and 0.7 % of the total capital costs in the studied cases. Finally, the cost reduction share of the total capital cost increases with increasing support structure size.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","Sustainable Energy Technology","",""
"uuid:33c216cf-517e-43dd-8bd5-61c7f650b712","http://resolver.tudelft.nl/uuid:33c216cf-517e-43dd-8bd5-61c7f650b712","Parametric Noise source model development of Counter Rotating Open Rotor","Klespe, L.","Sahai, A.K. (mentor)","2017","Counter Rotating Open Rotors are a possible response to the demands of future aviation propulsion. Their benefit of low fuel consumption grants operation particularly for rising kerosene price. Detrimental is the high level of noise emission, especially tonal sound. For prospective development and implementation to modern aviation, noise prediction tools are essential. Delft University of Technology currently develops an automated aircraft design tool, which considers different disciplines. One of which is the noise prediction tool called INSTANT, already capable to predict noise emissions of turbofan engines. This thesis report presents and explains the development of an in-design noise prediction tool for Counter Rotating Open Rotors as a starting point for an advancement in application variability of INSTANT. A two-system approach, based on an analytical and a semi-empirical tool, is implemented to increase the tool’s fidelity and optionally keep its computation time minimum. The analytical tool relies on blade discretisation and aerodynamic properties, while the semi-empirical tool is based on empirical analogies. To a certain extend, the user is able to choose the algorithmof evaluation. Both tools show good predictive performance, however the analytical tool offers potential to further refine its capabilities of prognosis.","","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Aircraft Noise and Climate Effects","",""
"uuid:943944d4-3430-4288-9eef-d04e34bb9f67","http://resolver.tudelft.nl/uuid:943944d4-3430-4288-9eef-d04e34bb9f67","Semi-Analytical Composite Oval Fuselage Mass Estimation","Roelofs, M.N.","Vos, R. (mentor)","2016","A semi-analytical weight estimation method is proposed for composite, oval fuselages, but is also applicable to conventional fuselages and to metallic materials. Loads applied to the fuselage include pressurization, steady-state maneuver loads and inertial loads. The primary structure around the passenger cabin is sized, based on first-ply failure using the Tsai-Wu failure criterion, global and local buckling. Moreover, maximum deflection due to transverse pressure is constrained for skin panels and sandwich panels. Sandwich panels are also sized for crippling and wrinkling. Empirical factors are used to calculate secondary structure and non-structural mass. In order to reduce in-the-loop calculation time, surrogate models of the sizing procedures are used, by means of neural networks. Verification of the sizing optimization was done by comparing the sized members with a genetic algorithm and validation of the failure calculations was done by finite-element analysis. It was found that the proposed method is capable of predicting metal, conventional fuselage mass satisfactorily, with acceptable breakdown of weights and estimated thicknesses. Additionally, the method can be used for unconventional aircraft configurations and composite material. Using composite material, a weight saving of around 15% is observed as compared to aluminum.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:366c5c7f-79d8-4895-ad55-6f3a7a6570f6","http://resolver.tudelft.nl/uuid:366c5c7f-79d8-4895-ad55-6f3a7a6570f6","Imprints in Dual Phase Hot Rolled Steel","Tombrock, A.J.C.","van der Zwaag, S. (mentor)","2016","DP600 HR is one of Tata Steels hot rolled products. It is a dual phase steel unique to Tata Steel for its two step cooling process and low coiling temperature. The finished product has encountered several surface defects, one of which are imprints. In order to find the root cause for the imprints a literature study, a factory inspection and a number of experiments have been conducted. To find the origin of the imprint two coils have been produced with the intention to create imprints on the surface. With these trials and the observations in the factories within Tata Steel it is found that a loose oxide layer of 4-10µm thick is formed at the end of the hot strip mill process. Due to the low coiling temperature a fair amount of water remains on the strip until further processing. At both the recoiler and the pickling line a build-up of loose oxide is seen. From both former trials and the trials done during this project it is seen that a build-up of oxide leaves imprints with a depth of 20 to 150 µm. In order to confirm that the imprints can indeed be produced by loose oxides, two experiments were conducted. Loose oxide particles and bearing balls have been pressed into the steel surface with the result in both cases of imprints that can be compared to the ones obtained in the factory. In this work a new procedure has been developed to test the growth of the oxide layer as well as its adhesion to the steel surface. 1. To grow an oxide layer the Thermo Mechanical Testing Simulator is used. This device is normally used to test hot deformability of metals but its heating chamber can also simulating the run out table two step cooling cycle. Both cooling rates are varied between 30, 60 and 90 K=s keeping initial, intermediate and final temperatures equal to the factory values. 2. To test the adhesion of the oxide to the steel a tensile test is performed with the aid of the ARAMIS optical strain measuring system. Since the ARAMIS system follows optically the changes in the steel surface during straining the oxide layer is usually previously removed, because it will break first and interfere with the measurement. However this fact is used here to our advantage since the strain that is necessary to remove the layer can now be quantified. This loss in measurement data corresponds well to the initial loss of oxide from the sample. From the ARAMIS data it is seen that increasing the cooling rate of the first cooling step decreases the amount of strain required to break the oxide from the steel. The second cooling step does not have a pronounced effect on the adhesiveness. The microscopy analysis showed an unknown oxide layer at the steel/oxide interface. This layer is mainly iron oxide but contains an unusual amount of chromium. It is presently not known how the chromium is distributed in the oxide nor what its effects on the properties of the scale are. It is concluded that the imprints are caused by a build-up of loose oxide on the work rolls. The imprints can be prevented by not using the levelling and scale breaker work rolls. The adhesiveness of the oxide to the steel under deformation can be improved by reducing the cooling rate on the first cooling step. Using the Thermo Mechanical Test Simulator a controlled layer of oxide can be grown on steel samples. The adhesiveness of the oxide layer can then be tested by means of a tensile test while being recorded by ARAMIS. This set-up can be further improved to obtain a standardised oxide adherence testing method.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:c08dfb7a-2d8b-4e5b-846e-ca018cb6386d","http://resolver.tudelft.nl/uuid:c08dfb7a-2d8b-4e5b-846e-ca018cb6386d","The feasibility of in-situ observations of Europa's water vapour plumes.","Huybrighs, H.L.F.","Vermeersen, L.L.A. (mentor)","2015","Europa, the second of Jupiter’s Galilean moons, has attracted strong interest from the scientific community. This is because it could harbour a sub-surface ocean of liquid water beneath its icy surface, which could be habitable. Recent observations indicate the existence of water vapour plumes at Europa’s south pole. The in-situ measurements of the plume particles (both neutral and ionized) may allow the direct sampling of Europa’s (potentially habitable) sub-surface ocean environment, without the need of an expensive landing or surface-ice penetrating mission. The instrument that could be able to perform in-situ sampling of the plumes is PEP (Particle Environment Package). PEP has been selected to fly on-board the European Space Agency's JUICE mission (JUpiter ICy moons Explorer) to be launched in 2022. PEP is under development now at the Swedish Institute of Space Physics (Institutet för rymdfysik or IRF) in Kiruna, Sweden. PEP is an instrument suite with six sensors to characterize the plasma and neutral environment in the Jovian system in-situ and remotely (via fast neutral imaging). The JUICE mission will perform two flybys of Europa. Related to the development of PEP and future observations of Europa’s plumes a Master’s thesis project with the following goal has been proposed: “Determine if PEP can observe Europa's water vapour plume by modelling: (a) the trajectories of neutral and ionized particles from Europa’s water vapour plumes with test-particle simulations and (b) the respective instrument observation.” In the test-particle simulations method the trajectories of particles through background electric and magnetic fields are determined by treating each particle as an isolated test particle. The project focusses on the JDC (Jovian plasma Dynamics and Composition analyser) and NIM (Neutral and Ion Mass Spectrometer) sensors that are part of PEP. We developed a model of the neutral and ionized plume particle environment. We simulated observations of these particles with respectively the NIM and JDC sensor, and demonstrated observations of plume particles is possible even for plumes that have lower mass flux (? 1 kg/s) than what has been observed (7000 kg/s). The developed neutral plume particle model is applicable when the particles in the plume are non-collisional. The ionized plume particle model is applicable to the case where the plume ion density is lower than the typical ion density at Europa. This limits the applicability to plumes with a mass flux ? 1 kg/s. We argue that future Europa plume models should consider the collisions between plume particles. Furthermore the expected high ion density will strongly influence the electric fields at Europa, this effect should be taken into account.","Europa; JUICE; water plumes; PEP","en","master thesis","","","","","","","","","Aerospace Engineering","Space flight","","Astrodynamics and space missions","",""
"uuid:3167fc76-1f65-4e26-bcb4-753ac6ec951e","http://resolver.tudelft.nl/uuid:3167fc76-1f65-4e26-bcb4-753ac6ec951e","Numerical Investigation on the Influence of Support Structure Modeling Strategies on the Loads of a Generic 5-MW Turbine on a Jacket Support Structure","Ying, T.","van Bussel, G.J.W. (mentor); Bierbooms, W.A.A.M. (mentor); Vorpahl, F. (mentor)","2013","Load simulations play an important role in the design, certification and optimization procedures for the development of reliable and cost efficient offshore wind turbines (OWTs). For load simulations of OWTs, aero-hydro-servo-elastic tools are used. However, the joint flexibilities of the support structures are generally not modeled in detail in these tools, which may lead to lower accuracy of the resulting loads. In this study, a generic 5 MW OWT in 50m water depth is investigated. The jacket support structure of the OWT is modeled by using different modeling strategies in which the joints are modeled in different levels of detail, so that the influence of these flexibilities on the loading of the OWT is inspected.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","Sustainable Energy Technology","",""
"uuid:802993a5-b218-4b7f-a7b4-9cf5375f7b38","http://resolver.tudelft.nl/uuid:802993a5-b218-4b7f-a7b4-9cf5375f7b38","Preliminary Structural Design for a Hypersonic UAV","Terhes, C.","Zandbergen, B.T.C. (mentor); Eggers, A. (mentor); Wijker, J. (mentor)","2014","The design and development of a small unmanned aerial vehicle is proposed in order to provide more accurate hypersonic flight data. The outcomes could improve the current shortage of hypersonic flight data and serve to understand and predict how test conditions may be different from actual test flight. Furthermore, the response of the structure and materials due to hypersonic speed will be investigated and stability and control methods during flight will be enriched. To achieve these goals, further investigation of the current configuration of the drone needs to be addressed in order to determine if the proposed structure is feasible. The vehicle and its mission have been called Hypresearch. The Hypresearch vehicle will be launched at the initial flight conditions of Mach 6 and 42 km altitude and it will self-sustain the hypersonic flight by its own rocket engine, descent and land. Thermal-structural challenges can be quite severe on hypersonic vehicles. Aerodynamic loads (mechanical loads) and aerodynamic heating (thermal loads) can be identified for all the flight stages. Besides, since Hypresearch needs to be introduced at the designated initial flight conditions, a launch system needs be designed or selected. The liftoff phase impose extra challenges, since the aircraft will be launched on the side of a rocket booster and undergo launch loads, such as g-forces, vibration, interface loads, not presented during the straight and level flight. After the loads on the vehicle were identified and categorized, the primary and secondary structure was set up using the strength of material and elastic instability approach. The materials selected were MAX phases for the leading edge and nose section, and titanium alloy for the main body. Likewise, titanium alloy was the material preferred for the secondary structure and attachments, as it deals the best with the expected temperature gradients. The following step was the positioning of the internal structure in respect to the constraints set by the project (no-trimming conditions during level flight), and the attachments concepts between the airframe and internal units, were proposed. After the initial structural design, the finite element model for the vehicle was set up to be used for the proposed structure’s analyses. The undertaken finite element analyses consist of: static, modal, pressure distribution, random and shock effect. The results show that the vehicle’s structure is likely to withstand the selected loading environment of the launch vehicle. From this model, the final mass budget of the vehicle’s structure was obtained. It was concluded that the structure is considered feasible with regards to the liftoff loads and within the mass budget requirement of a maximum 35 kg. In a nutshell, the graduation project is focused on finding simple solutions to some structural design problems and providing an accurate analysis of the vehicle, in order to confirm the feasibility of the design under investigation.","structural design; hypersonic vehicle; FEM; FEA","en","master thesis","","","","","","","","","Aerospace Engineering","Space Flight","","Space Engineering","",""
"uuid:b5d75c35-fd97-4fe3-a71d-5dec7f174eb0","http://resolver.tudelft.nl/uuid:b5d75c35-fd97-4fe3-a71d-5dec7f174eb0","Series Hybrid Electric Aircraft: Comparing the Well-to-Propeller Efficiency With a Conventional Propeller Aircraft","Lenssen, R.H.","Melkert, J.A. (mentor)","2016","THE aviation industry is responsible for 12% of the total transportation impact of CO2 while awareness, for decreasing the total carbon footprint, is rising. Both the aerospace and the automotive industry are facing an increasing pressure from society to make the transportation sector more sustainable. Within the automotive industry slowly an increase in electric vehicles can be noticed (<1%). Also in the aerospace industry a rise in electrification can be seen, with small aircraft as the E-Star and E-Fan (two seaters) as commercial examples. Electrification of the transportation sector could further result in a decrease in noise and an increase in lifespan of parts as vibrations are decreased. This master’s thesis is written in conjunction with the chair Flight Performance and Propulsion at the faculty of Aerospace Engineering at the Delft University of Technology. The main purpose is to gain more insight in modelling an (hybrid) electric aircraft and the potential improvements with respect to well-to-propeller efficiency (usefull energy over total energy ratio). This is achieved by first creating a baseline conventional propeller aircraftmodel (ATR72) and then a hybrid electric version of the same aircraft. The variations between the sub-models and validation data are calculated in order to have a feeling for the accuracy of each individual model. Furthermore, both the theoretical and current practical state of technologies are used in the overall model. Finally, a sensitivity analysis is performed to find the driving parameters in the outcome of the model. The analysis of the series hybrid electric aircraft showed first of all that the expected advantages of the concept are ’small to non-existent’. The electric energy used to charge the batteries should first of all come from a renewable source of energy to make the concept feasible. Secondly, the theoretical limits of technology should be approached in order for the well-to-propeller efficiency to exceed that of the conventional ATR72 aircraft (with a maximum of 2%). It is seen that the model converges to an all electric version of the ATR72 if the battery energy density is increased to 2,802 [Wh/kg], this would correspond to the theoretical limit of Lithium Sulphur battery-technology. Furthermore, for an increase in voltage the battery efficiency decreases while all other components will improve in efficiency. The optimum is found in increasing the voltage up to the practical limit of 25 [kV]. Electric propulsion creates new design possibilities as distributed propulsion and variable shaft-speed. Within this thesis it is however shown that the ’benefits’ of distributed propulsion do not outweigh the downsides (increase inweight and decrease in efficiency of all components). Furthermore electric motors allow for temporary torque overloading, by decreasing the rotational speed and increasing the torque, the overall result is an increase in efficiency, which could for example be usefull during the climb or take-off phase. Concluding, the concept of series hybrid electric aircraft is at this moment in time rendered infeasible. The potential within a 35 year time-frame is doubtfull as especially battery technology should improvewith at least 400 [%]. In order to accelerate the transition to hybrid electric or all electric aircraft, the main areas of research should be: battery technology and the integration of alternating current and superconducting materials in rotating machine parts.","Electric Flight; Series Hybrid; Optimisation; Modelling; Aircraft; ATR72","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:9ea7cdf8-ae8b-4131-8647-c07794fe4a20","http://resolver.tudelft.nl/uuid:9ea7cdf8-ae8b-4131-8647-c07794fe4a20","Real-time Position and Attitude Determination of the Stratos II Sounding Rocket","Tong Minh, B.","De Mooij, E. (mentor)","2012","Currently, the student amateur rocket association Delft Aerospace Rocket Engineering (DARE), is designing a small sounding rocket to carry payloads to over 50 km, the Stratos II. Proper operation of this rocket will require an on-board position and attitude determination system. In this thesis, it will be researched how this position and attitude determination can be performed. In essence, the research can be divided into three main topics: simulation, measurement and estimation. Flight estimation is the main goal of the research, while simulation and measurements are prerequisites to estimation. A measurement system with low-cost sensors has been designed and built, and during calibration the performance of these sensors has been established. This measurement system has flown in an actual small sounding rocket, the Stratos II concept launcher, and acceleration, angular velocity and atmospheric pressure data have been acquired. Several estimators have been researched, from which the extended Kalman filter was selected as the most suitable to estimate the position and attitude. The accelerometer and gyroscope measurements are used to propagate the state, and the other measurement data to improve the state estimate, and to estimate various noise factors of the sensors. Measurements are generated from simulations of nominal and non-nominal flights, with nominal and non-nominal sensors, to verify the performance of the estimator. It was found that both the flight trajectory, as well as sensor noise factors such as bias and non-orthogonality strongly affect the estimation result. As only coarse requirements on the position and attitude determination system are available, it cannot be concluded with certainty that the developed measurement system and estimator are suitable for the Stratos II. However, preliminary analysis performed in this thesis, indicates that this is the case. Furthermore, in this thesis clear guidelines are established to improve the estimator performance, should the developed system not satisfy the final requirements.","stratos; navigation","en","master thesis","","","","","","","","","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:65d6c2ba-3421-4c4b-a358-0891e79a7652","http://resolver.tudelft.nl/uuid:65d6c2ba-3421-4c4b-a358-0891e79a7652","Computational modelling of Dielectric Barrier Discharge Plasma Actuators for Aerospace Flow control applications","Syed, Z.A.","Kotsonis, M. (mentor)","2016","","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:11e0f459-82c0-4650-ae4a-8d755abc3d6e","http://resolver.tudelft.nl/uuid:11e0f459-82c0-4650-ae4a-8d755abc3d6e","Supply Chain Quality Management within the Aeronautical Industry: Case Study at the Airbus Single Aisle Fuselage Assembly","Witt, W.","Sinke, J. (mentor)","2016","Within the aeronautical industry product quality is an inevitable key factor to guarantee safety and customer satisfaction. In the last years the increasing complexity of modern aircraft, however, has led to an immense demand for collaboration of different manufacturers in order to stay competitive. Therefore, there is an increasing interest in establishing effective supply chains and ensuring not only internal quality, but also applying existing quality management principles and instruments on the whole supply chain. In order to contribute to the recent developments in the emerging research field of supply chain quality management, this master thesis follows a twofold approach by first, reviewing the current state of the art and pointing out the derived best practices and, second, conducting a case study at the Airbus Single Aisle fuselage production, hereby analyzing the industrial processes and making recommendations on how to improve the existing Airbus processes. The in-depth knowledge acquired during the case study helps to understand how the aeronautical industry strives to fulfill the authority requirements and customer expectations in terms of product quality and how the existing quality management methodology is applied and expanded into the growing supply chains of aircraft manufacturers. In addition, the developed methodology and the identified factors for effective supply chain quality management as well as the weaknesses and strengths of the applied processes provide a foundation for further research within this field.","supply chain; quality; management; aerospace; case study","en","master thesis","","","","","","","","2021-07-08","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:e09388ce-5c6b-4bb5-8465-1fa431a2ce64","http://resolver.tudelft.nl/uuid:e09388ce-5c6b-4bb5-8465-1fa431a2ce64","Implementation and Analysis of a Semi-Empirical Vortex Generator Model in OpenFOAM","Moreira Ribeiro, A.S.","Hulshoff, S.J. (mentor)","2017","Passive vortex generators (VGs) are small plate-devices that are placed on the top of wings, in an array configuration, in order to delay or event prevent stall. Due to their small size, when compared to the wing, a highly refined mesh is required to accurately simulate the flow behaviour downstream the VG location. As a consequence, the computational time required for a high fidelity 3D computational simulations is very large. In recent years, there have been efforts to create models that allow the computation of the VGs effect without grid them. Reducing this way the computational effort. During this thesis a semi-empirical model, the Wendt model, was implemented in OpenFOAM and later analysed and compared with gridded VG simulations. The Wendt model is used to predict the vortex circulation and peak vorticity. These entities are then used to calculate the vortex velocity profile at a certain position downstream the VG location. In this projects besides the predictive capabilities of the model, it was tested the hypothesis that to mimic the flow behaviour of a gridded VG simulation, it is enough to impose a vortex velocity profile at a certain position downstream the VG location. It was seen that the Wendt model is able to predict reasonably well peak vorticity and circulation on the tested parameter range, but for higher values of freestream velocities and lower values of height-to-boundary-layer-thickness-ratio and aspect ratio. Furthermore it was seen that, although the implemented model produce inconsistent flow results, the implementation made can be used for that propose. With the correct vortex circulation, peak vorticity and vortex position inputs, it is possible to mimic the correct vortex development as well as the correct flow behaviour, but only far from the VG location, where the influence of the vanes in the streamwise velocity is no longer relevant.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Aerodynamics","",""
"uuid:de4a4261-0948-45e9-9525-b78e2a664af2","http://resolver.tudelft.nl/uuid:de4a4261-0948-45e9-9525-b78e2a664af2","Effectiveness of Thrust Vectoring Control for Longitudinal Trim of a Blended Wing Body Aircraft","Chen, H.","Voskuijl, M. (mentor); Ciampa, P.D. (mentor)","2015","The application of thrust vectoring on civil transport aircraft has only been studied by a few individuals. Quantified investigations need to be carried out to search for the potential benefits of the application of thrust vectoring control on a civil transport aircraft. Blended Wing Body configuration is a novel aircraft concept. Due to the absence of conventional tails longitudinal controllability become part of the key challenges of this configuration. It is therefore the objective of this thesis project to carry out quantified flight mechanics analyses on the effectiveness of controlling a Blended Wing Body aircraft with vectoring thrust. As a starting point flight mechanics simulations under steady level flight conditions in longitudinal plane are conducted in this project. Through this project a thrust vectoring model, which contains the calculation of nozzle deflection angles based on nozzle deflection controls and the calculation of engine thrust loss due to nozzle deflections, is developed and embedded in a flight mechanics toolbox used for the flight mechanics simulations. The flight mechanics simulations of thrust vectoring control are then carried out with a series of nozzle deflections, flight conditions, aircraft mass and CG locations. From the simulation results it is investigated that for the Blended Wing Body configuration tested in this project, thrust vectoring control under steady level flight conditions is much less effective than the conventional aerodynamic control surfaces. The maximum effectiveness ratio between thrust vectoring control and conventional aerodynamic control surfaces obtained in this project is about 11.2%. With extensive flight mechanics simulations, the way that aircraft flight conditions, mass and CG locations affect the effectiveness of thrust vectoring control is analysed through this project.","Blended Wing Body; thrust vectoring; control effectiveness","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:9a3d4bdb-00a4-4ddf-b643-ebc11b2fa3b2","http://resolver.tudelft.nl/uuid:9a3d4bdb-00a4-4ddf-b643-ebc11b2fa3b2","Towards Automated Classification of Aircraft Maintenance Documentation","Scherp, L.","Verhagen, W.J.C. (mentor)","2016","Airline maintenance technicians (AMTs) often still rely on paper-based documentation when performing a task. In the limited time during unscheduled tasks, obtaining the right information from these documents can take up to 30% of the available time. To speed up this process, in this thesis it is explored how an automated system can be created that can pre-classify digital maintenance documents so an AMT can quickly retrieve task-relevant documents. Using a dataset of 14.000 Airworthiness Directives, the main objective is to compare document classification techniques ranging from Boolean to Machine Learning on various document properties (e.g. language), to determine a recommended approach for such a system.","maintenance documentation; aircraft maintenance; machine learning; automated documentation system","en","master thesis","","","","","","","","2017-06-01","Aerospace Engineering","Control & Operations","","Air Transport & Aerospace Operations","",""
"uuid:5a771843-d354-4f71-a767-6d711a38b832","http://resolver.tudelft.nl/uuid:5a771843-d354-4f71-a767-6d711a38b832","The effect of asymmetric base flaps on the drag of a tractor-trailer for four crosswind angles: A numerical and experimental study","Kruijssen, F.","Dwight, R.P (mentor); Van Raemdonck, G.M.R (mentor)","2017","With the increasing temperature due to global warming CO2 emissions have to be reduced. Tractor-trailers are very fuel inefficient making them a good candidate for drag reducing devices to reduce fuel use. In this thesis the focus lies on the base of the trailer, where flaps will be added. The aim is to find the increase in drag reduction when using the optimum asymmetric flap angle per crosswind angle instead of the wind-averaged axisymmetric flap angles. Using the results of steady-state CFD calculations and force measurements in the open jet facility wind tunnel on a scaled and simplified European tractor-trailer model, the optimum asymmetric flap angles can be found and verified. Furthermore, the behaviour of the streamlines over the flaps in all crosswind angles has been tested using oil in the wind tunnel. Although the differences between the baseline drag coefficients found in the wind tunnel and with CFD were quite high, the difference in predicted drag reduction when using flaps was at most 15 drag counts. Furthermore, the behaviour of the streamlines over the flaps was quite alike in both the experimental and numerical analysis. Comparing the drag reduction produced with asymmetric flaps to the drag reduction produced with axisymmetric flaps leads to a minimal decrease in drag.","","en","master thesis","","","","","","","","2020-03-13","Aerospace Engineering","Aerodynamics","","","",""
"uuid:809ca182-ee8c-4214-b1ea-16441d70559d","http://resolver.tudelft.nl/uuid:809ca182-ee8c-4214-b1ea-16441d70559d","Single Pilot Commercial Operations: A Study of the Technical Hurdles","Faber, A.","Mulder, M. (mentor)","2013","History has shown that a larger flight crew does not per se imply that aircraft operations will be safer. The goal of this thesis is to determine the technical hurdles to Single Pilot Commercial Operations (SPCO). Continued technological developments, the upsurge of commercial Unmanned Aerial Systems, the non-negligible cost of air crews, and yet, stagnation in commercial crew reductions since 1980 are reasons to clarify the current technical hurdles to SPCO. The research was initiated with a broad literature survey. It was found that advances in technology and human factors understanding have made each historical crew reduction possible, through a redistribution of tasks across (fewer) humans, automation, supporting infrastructure and accompanying procedures. An exhaustive list was then formulated of all issues that could potentially affect a reduction to SPCO. Consequently, in-depth research of each issue determined the most predominant challenges to SPCO are; a. providing the single pilot with the correct situational awareness at a manageable workload; b. ensuring adequate monitoring of pilot performance without an on-board human co-pilot; and c. ensuring redundancy in case of incapacitation. Finally, Single Pilot Incapacitation Redundancy (SPIR) solutions were explored by means of a scenario analysis and functional analysis. The greatest challenge to SPIR turns out to be the setting of the incapacitation detection sensitivity threshold; avoiding excessive false warnings (alarm problem) yet retaining immediacy for timely recovery of stable flight; both incapacitation detection and seem-less control take-over are tasks more suited to the adaptability of humans. A concept for a SPCO flight deck has been presented in which these issues become obsolete.","Single Pilot Commercial Operations; Human Factors; SPCO; Crew reduction; Crew size; Flight crew; Single Pilot","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Simulation","","Master Aerospace Engineering. Track 3 Dynamics and Control of Aerospace Vehicles","",""
"uuid:e8689aba-d582-426b-b330-56eea20d4da9","http://resolver.tudelft.nl/uuid:e8689aba-d582-426b-b330-56eea20d4da9","High-fidelity aerodynamic shape optimization of wind turbine blades","Dhert, T.","Ashuri, T. (mentor); Martins, J.R.R.A. (mentor); van Zuijlen, A.H. (mentor)","2015","Recent improvements in accuracy and effciency of numerical simulation techniques in the field of engineering have led to an increasing interest in applying high-fidelity models for wind turbine design. Computational Fluid Dynamics (CFD) based on Reynolds-Averaged Navier-Stokes (RANS) equations in a co-rotating reference frame has shown promising results for performing design analysis. However, using high-fidelity techniques for wind turbine blade design optimization is not yet fully understood. Especially, high-fidelity aerodynamic shape optimization for wind turbine blades has not yet been employed in the industry due to its computational ineffciency when large number of design variables are used with traditional techniques such as finite difference derivatives and gradient-free optimization methods. This dissertation presents an effcient and robust high-fidelity aerodynamic shape optimization methodology for rotating ow problems. The high-fidelity optimization method consists of a multiblock, structured RANS-based CFD simulation tool, a discrete adjoint method, a shape parametrization method, a mesh perturbation technique and a gradient-based optimizer. Steady-state solutions are obtained by the RANS-based CFD analysis method based on a co-rotating reference frame. The turbulence model is a segregated one-equation SA model. Total derivatives of the ow solution and constraint(s) are computed by a discrete adjoint method. For reducing the computational cost of computing partial derivatives that are required in the discrete adjoint method, forward automatic differentiation is used. Once the total derivatives and ow solution are computed, the gradientbased optimizer based on sequential quadratic programming computes a better design by using an augmented Lagrangian formulation with quasi-Newton approximations for the Hessian. The change in design variables obtained by the optimizer is parametrized with a Free Form Deformation (FFD) volume approach. After performing surface perturbations, the mesh is deformed using a hybrid mesh deformation scheme, that combines an algebraic and linear elasticity method. The linear elasticity method based on finite elements is used for large perturbations, while the algebraic method attenuates small perturbations. When the optimality condition is satisfied, the iterative procedure ends with the optimal design. Verification and validation of the developed codes are performed using the NREL VI wind turbine. The RANS-based CFD solver is validated by comparing numerical results with NREL VI sequence S experimental data. The solver resolves attached ow conditions accurately, while separated ow conditions lead to inaccurate ow solutions due to insufficient transition and turbulence modeling. DES can resolve the inaccuracy associated with separated ow conditions. Total derivatives of the adjoint method are verified by comparing derivatives of the complex and finite difference method. The quality of (perturbed) meshes are verified by using mesh quality metrics. Correct shape parametrization is assured after careful examining the direction and magnitude of the deformations. Since the NREL VI wind turbine blade rotates at a constant angular velocity, the power generation is considered to be only dependent on torque. Therefore, the objective of the optimization is maximizing the torque coefficient with shape, twist, and pitch design variables. Thickness constraints between 15% and 50% are added for representing a wing box. The thickness constraints impose thicknesses of the blade to increase only up to 300% of the original thickness. No reduction in thickness with respect to the baseline design at that region of the blade is possible in order to fit the original wing box. For future research, the objective and constraint function(s) can be easily adapted to more realistic and modern rotating ow problems. From the aerodynamic shape optimization of the NREL VI blade, an increase of at least 22.4% in torque is achieved. The airfoil shapes tends to become more cambered and less thick. The nose of the airfoil is more aligned to the in ow. At root section of the wind turbine blade, the trailing edge of the airfoil acts as a ap in order to obtain higher loads at low relative velocity. Three different mesh refinements are employed for optimization. The first mesh is a coarse mesh that is used for verification purposes of the optimization procedure. The second mesh is employed for obtaining accurate aerodynamic shape optimization results. The final design variable values of the medium refined mesh are projected on the most refined mesh, because computational costs would be too high for performing optimization. An increase of 29.1% in torque is achieved, indicating that the increase in optimized torque for more refined meshes will be higher when using coarser meshes. Since wind turbines are operating in a range of wind speeds, multipoint optimization from cut-in to rated wind speed is performed. Similar results as in single-point optimization are achieved. An increase of 22.2% in Annual Energy Production AEP is obtained. The adjoint method and high-fidelity aerodynamic shape optimization methodology allow designers to examine accurately the trade-off between various design variables at the early stage of the design process. For future research purposes, aerostructural and aeroelasticity optimization can be employed with the same framework","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Aerodynamics","",""
"uuid:3eda6d83-9aaa-4632-8037-b44107a084e3","http://resolver.tudelft.nl/uuid:3eda6d83-9aaa-4632-8037-b44107a084e3","Prandtl tip loss factor assessed","Ramdin, S.F.","van Zuijlen, A.H. (mentor)","2017","The Blade Element Momentum (BEM) theory is widely used for the design of wind turbine blades and predicting aerodynamic loads because of its ability to compute fast and reasonable results. However, the Prandtl tip loss factor is needed to improve the accuracy of the results near the tip. In this thesis the limitations and shortcomings of this factor are identified, by using higher fidelity methods. The results show that the Prandtl tip loss factor should be improved on the account of the radial movement of the flow and that there are four tip loss factors that outperform the others.","tip loss factor; Prandtl tip loss factor; BEM","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:bf64c0eb-fc2d-4e3a-90ed-696071625606","http://resolver.tudelft.nl/uuid:bf64c0eb-fc2d-4e3a-90ed-696071625606","'Towards a Proper Understanding of Fatigue Crack Growth and Crack Closure","Hogeveen, J.J.","Alderliesten, R.C. (mentor)","2016","Conventional theories to describe and predict FCG are based on a SIF parameter, ΔK. If ΔK is used as similitude parameter to predict FCG, an R-effect arises. This R-effect can be accounted for by means of plasticity induced crack closure: A plastic wake behind the crack tip causes the crack to close before a zero tensile load is applied. As such ΔK is adapted to an effective ΔK, ΔKeff. If ΔKeff is used for similitude the R-effect disappears.These theories have recently been disputed and an alternative, SER dominated FCG description model has been proposed. This research discusses the confusion about using ΔK for similitude and approaches FCG also from a SER perspective. Experiments are designed and executed in air and vacuum environment to obtain a better understanding of fatigue, the R-effect and crack closure. The experimental results show that ΔK is an improper similitude parameter and that the R-effect is an artefact of choosing ΔK for similitude. Instead of that, fatigue should be approached from a SER perspective. Furthermore the research shows that the R-effect is not caused by (plasticity induced) crack closure.","G; FCG; R-effect; Stress Ratio; Crack Closure; Plasticity Induced Crack Closure; SIF; SER; Strain Energy Release; Fatigue; ΔK; ΔKeff","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:219f6326-95c9-445a-aa87-413cc80ea819","http://resolver.tudelft.nl/uuid:219f6326-95c9-445a-aa87-413cc80ea819","De-noising terrestrial laser scanning data for roughness characterization of rock surfaces","Altunda?, D.","Khoshelham, K. (mentor); Nygan-Tillard, D. (mentor); Menenti, M. (mentor)","2009","To measure roughness a number of traditional measurement methods have been developed such as linear profiling, compass and disc clinometers. Although these measurement methods have been widely used, they are time consuming, and labor intensive. The accuracy of the local measurements depends heavily on expertise and measurements are limited to places that are accessible. Therefore, the demand for ways of acquiring roughness information quickly and with a high spatial resolution and accuracy for surfaces out of human reach is increasing. Terrestrial laser scanning (TLS) is a data acquisition technique promising to fill all these needs. However, data acquired by terrestrial laser scanner devices always contain noise. Therefore, using the raw laser data for roughness characterization can cause inaccurate and unreliable results. In order to confirm that terrestrial laser scanning technique can replace the traditional measurement methods for roughness characterization it is essential to remove noise present in the data as accurate as possible without distorting the detailed features underlying the original data. The research presented in this thesis focuses on analyzing the influence of terrestrial laser scanner (TLS) instrument noise on rock surface roughness characterization. To characterize roughness the roughness length method is used. Linear profiles are generated on the rock surface and from these profiles roughness data are obtained using both terrestrial laser scanner data and manual measurements. The manual measurements are used as reference for the evaluation of the results from the laser scanner data. From the profiles the fractal parameters are obtained to quantify roughness using the roughness length method. Both raw data and denoised laser scanner data are used to obtain fractal parameter values. With respect to the selection of the most appropriate threshold value to distinguish the original data from the laser range noise, an experiment was performed using the wavelet denoising approach. In this experiment, the threshold values were changed incrementally until the fractal dimension values approached the values of the reference data. If the selected threshold value was too small to remove noise then the denoising procedure resulted in the noise being underestimated (e.g. 0.001m for our case). In contrast, if the threshold value is too high then the denoising procedure resulted in the noise being overestimated. The results clearly showed that the selection of threshold values in denoising procedure play a significant role in changing the values of the fractal dimension. However this method was only used to see the effect of the threshold value on the fractal parameters. It was concluded that the best approach is to first estimate the noise level in the laser data and then determine the threshold values. For this reason two methods were applied to determine the noise level (Donoho-Johnstone’s and Menenti-Ritchie’s methods), and then they are used in different threshold estimation methods. In total 10 different thresholding methods, including the hard and soft modes, were performed on the wavelet coefficients obtained separately from discrete wavelet transform and wavelet packets. Donoho-Johnstone’s, Fixed form, hard thresholding method and Birge-Massart’s, Penalized medium soft, thresholding methods when applied to the coefficients of wavelet packets resulted in very close fractal dimension values to the reference values in x directional laser profile. However, for y directional profiles Birge-Massart’s Penalized medium hard thresholding method resulted in the closest value to the reference data. In this research it is showed that noise can be successfully eliminated to such a degree that accurate measurement values can be obtained from laser scanned data for rock surface roughness characterization.","terrestrial laser scanning; de-noising; roughness; wavelet","en","master thesis","","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","Geomatics","",""
"uuid:3512f664-92d0-464f-a692-41cc21e36f19","http://resolver.tudelft.nl/uuid:3512f664-92d0-464f-a692-41cc21e36f19","Tracking Free Surface Flows Using the Least Squares Spectral Element Method","Lantsheer, M.","Bijl, H. (mentor); Gerritsma, M.I. (mentor)","2010","","Discretisation; Least Squares; Spectral Elements; Poisson; Crank-Nicolson","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:72168d96-2956-40ad-b2be-38626d6ec209","http://resolver.tudelft.nl/uuid:72168d96-2956-40ad-b2be-38626d6ec209","Formation Control of Quadrotor Vehicles","Lopes Rocha, J.P.","Cunha, R.M.M.A.C. (mentor); Silvestre, C.J.F. (mentor)","2015","The use of multiple quadrotors to perform cooperative tasks is an active research ?eld of crucial importance. One particular mission of interest involves a formation of quadrotors performing infrastructure inspection autonomously. This thesis describes a scenario where a Target quadrotor is performing a task in a GPS-denied environment, and two Sensor quadrotors with GPS capabilities estimate the Target’s position combining their positions with bearings-only measurements. The selection of the Sensors’ positions can greatly a?ect the estimation performance, motivating the optimization of several objective functions based on the Fisher Information Matrix (FIM). Two novel estimation algorithms are created and tested for both cases where the Target is stationary and moving. The results show geometric con?gurations that increase the estimation accuracy, illustrating the importance of maximizing the FIM for Target localization using quadrotors. Assuming a double integrator model for the target vehicle, an LQR controller is combined with the nonlinear estimator to achieve tracking of a desired trajectory. The results show the in?uence of the Sensors’ positioning not only on the estimation error, but also on the di?erence between the true and desired position of the Target. Finally, a network localization problem with multiple Targets and two Sensors with full knowledge of their position is considered. The Targets estimate their position using not only bearings measurements coming from one of the Sensors, but also coming from another Target. A construction method of network formations that guarantees the convergence of the Targets’ estimates to their actual positions is described and demonstrated.","Multi-quadrotor systems; Optimal localization geometries; Bearings-only measurements; Network localization","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Dynamics & Control and Avionics","","Double Degree Programme IST/TUDelft","",""
"uuid:d2aa12b3-7ed6-4f63-85c0-ac413291feb4","http://resolver.tudelft.nl/uuid:d2aa12b3-7ed6-4f63-85c0-ac413291feb4","Multi-View ICP for 3D reconstruction of unknown space debris","Paun, I.","Kuiper, H. (mentor); Ahrns, I. (mentor)","2014","With a growing threat from space debris, it has become more important for space agencies to have a means of reducing the probability of escalating the dangers posed by it. For this purpose, servicer satellites need to be built. These satellites need to be able to interfere with “dead” satellites and deorbit defunct satellites. In order to be able to navigate around these types of objects, it is necessary for the servicer satellite to be able to determine its position around the object and the relative motion between the debris and the servicer. This thesis describes an algorithm that determines the trajectory of the servicer satellite based on a 3D reconstruction of a model of the target object. It takes 3D point clouds from a sensor and transform these point clouds into a 3D model that can be used by the servicer to navigate and determine its position around the target object. The approach uses a simulation of a LIDAR instrument to obtain the data which is then used as input for the algorithm to reconstruct the path of the servicer satellite. This thesis was done at Airbus Defense and Space as it is currently activley trying to develop the capability to interfere with space objects. The resulting algorithm can perform a 3D reconstruction of a target object in real-time if appropriate parameters are being used and it can also determine the position of the servicer around this model. Moreover, it can also reconstruct the trajectory for the observer around its target.","ICP; global iterative closest P\point; space debris detection; satellite vision; debris removal; Envisat; algorithm; point cloud; LIDAR; iterative closest point","en","master thesis","","","","","","","","","Aerospace Engineering","Space","","Engineering","",""
"uuid:d0450f45-f383-411e-b455-1eda6ace08e8","http://resolver.tudelft.nl/uuid:d0450f45-f383-411e-b455-1eda6ace08e8","Relaxed Static Stability Performance Assessment on Conventional and Unconventional Aircraft Configurations","Jansen, Q.J.M.","Vos, R. (mentor)","2015","This thesis report researches the influence of a reduced stability margin on the aircraft performance of conventional and unconventional aircraft configurations. Unconventional configurations are defined as canard and three-surface aircraft.","Relaxed Static Stability; Tail Sizing; Unconventional; Stability Margin; Ground effect","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","Flight Performance and Propulsion","",""
"uuid:c62fc3a4-6aea-4180-b125-ac54fede0762","http://resolver.tudelft.nl/uuid:c62fc3a4-6aea-4180-b125-ac54fede0762","Fatigue crack growth in Selective Laser Melted Ti-6Al-4V","Michielssen, J.","Alderliesten, R.C. (mentor); Lopes dos Santos, B.F. (mentor); Rans, C.D. (mentor)","2017","This research investigates the effect of a varying build orientation and different heat treatment on the crack propagation properties of SLM Ti-6Al-4V. Both crack propagation rate and direction are investigated. Fatigue tests are performed with a constant cyclic load and single edge notch specimens. Ten unique types of specimens were tested by combining five different build orientation (0°, 30°, 45°, 60° and 90°) with two different heat treatments (Stress relieved and Hot Isostatic Pressing). In the end, similar crack propagation rates were measured for all specimens. Although, small differences were seen in the microstructure and DIC analysis, they did not seem to change the crack propagation rate. This observation led to the conclusion that the crack propagation rate is not influenced by a change in build orientation or a change in heat treatment. On the other hand, the measured crack paths showed some differences. Small crack deflections were found for 30° - SR and 45° & 60° - HIP, while all other specimens had cracks propagating in a direction normal to the applied stress. As only off-axis specimens showed repetitive crack deflections, it can be concluded that the anisotropic microstructure is causing this behaviour. However, no conclusive explanation could be given based on the data gathered in this experiment. It is expected that different mechanisms caused the crack deviations as it happened in both heat treatments but for different orientations. Further research in this specific field in needed to explain the measured behaviour.","Fatigue; Damage Tolerance; Ti-6Al-4V; SLM; Additive Manufacturing","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","Structures","",""
"uuid:4bdc1b59-9ba5-4ac8-9aba-6ae916e1f58e","http://resolver.tudelft.nl/uuid:4bdc1b59-9ba5-4ac8-9aba-6ae916e1f58e","LOFAR on the Moon: Mission Configuration and Orbit Design","Antignac, L.","Noomen, R. (mentor); Cruijssen, H. (mentor)","2015","Unperturbed observation of deep space radio waves is impossible to achieve from Earth but could be managed if the instruments were positioned in a place shielded from Earth, such as the far side of the Moon or the Shackleton crater, situated at its South Pole. In order to keep the costs of such a mission as low as possible, the VEGA launcher needs to be used. This MSc Thesis studies the possible mission designs and trajectories to land a minimum of 150 kg of payload in such a place. For the eight mission scenarios considered, the spacecraft can either use a Chemical Propulsion System (CPS) or an Electric Propulsion System (EPS) for the transfer to Low Lunar Orbit (LLO), the spacecraft can either circularize around the Moon in a polar orbit or in an orbit situated in the lunar orbital plane, and the relay can either be sent to the Lagrangian point L2 or be landed on the Moon. After preselecting the four feasible mission scenarios, a Matlab program was coded to simulate the trajectories flown from Low Earth Orbit (LEO) to LLO using either a CPS or an EPS, the trajectory from LLO to L2 using a CPS which is applicable to certain mission scenarios only, and the trajectory for the descent and landing also using a CPS. The inclination of the lunar orbital plane with respect to the launching site varying during the year, it was chosen to take the worst-case scenario for this study. The subsystem masses were then assessed to determine the payload mass that can be placed on the Moon. It was found that with the most successful CPS mission 34 kg of payload could be placed on the rim of the Shackleton crater, while 107 kg could be placed at that same place when using an EPS. For both cases, no relay module was sent to L2 and the spacecraft circularized around the Moon in a polar orbit. Even though the payload mass does not meet the 150 kg requirement, it should not be forgotten that this study belongs to the preliminary design phase of the mission: looking into the recommendations for further work and altering several parameters could change the final outcome.","LOFAR; Trajectory; Transfer; Design; Mission; Orbit; Moon; Configuration","en","master thesis","","","","","","","","","Aerospace Engineering","Space Flight","","Space Exploration","",""
"uuid:11de9007-cb02-4540-bb42-3b537d86ef7e","http://resolver.tudelft.nl/uuid:11de9007-cb02-4540-bb42-3b537d86ef7e","Flap Side-Edge Noise Reduction","Crepain, T.P.","Veldhuis, L.L.M. (mentor); Eitelberg, G. (mentor)","2015","","Aeroacoustics; CFD; Beamforming; Flap noise","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:c68563ea-554a-4afd-b9d6-378ac80f42c5","http://resolver.tudelft.nl/uuid:c68563ea-554a-4afd-b9d6-378ac80f42c5","Improving Spatial Resolution of Tomo-PIV using Particle Tracks with Vortex-in-Cell","Singh, P.","Scarano, F. (mentor)","2016","Tomographic PIV is one of the most recent and advanced tools used in experimental fluid dynamics. Low spatial resolution is currently a problem in large scale tomo-PIV as concentration. A novel technique is proposed which leverages the temporal information of full Lagrangian particle tracks to improve the spatial resolution of tomo-PIV in low seeded flows. The method produces dense Eulerian velocity field from sparse scattered particle tracks obtained from state of the art particle tracking algorithms. The method is based on a variational principle wherein iterative simulations of Vortex-in-Cell method (Schneiders et al., 2014) are performed to minimise the norm of the difference between simulated and measured velocity of scattered particles. The LBFGS method, which is a gradient based numerical optimisation technique, is utilised to solve this optimisation problem. Gradient of the cost function with respect to the system’s degree of freedom is computed using the adjoint method. Initial and boundary conditions are taken from tomo-PIV measurements. A two dimensional analytical vortex blob is considered for the numerical validation of the proposed method. Both qualitative and quantitative analysis are performed for its detailed assessment. The method demonstrates significantly improved reconstructions as compared to methods which rely on instantaneous information of the particles. It is also revealed that utilising longer particle tracks within the methods framework further improves the reconstruction quality and spatial resolution. The method even shows significant noise reduction capability which enhances when using longer tracks. The proposed method is also validated in an unsteady and evolving flow field by simulating the Von-Karman shedding in the wake of a long cylinder. Even at very low seeding densities the method successfully reconstructs the main structures of the flow. Providing more temporal information again proves to augment the methods ability to produce more accurate reconstructions.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:251efbee-344e-4b7f-9349-4d5d87f13b19","http://resolver.tudelft.nl/uuid:251efbee-344e-4b7f-9349-4d5d87f13b19","Hydrogen-powered Ultra-large Cargo Aeroplane: A study into the Economic & Operational Feasibility","Hordijk, D.R.","Visser, H.G. (mentor)","2017","A study into the operational and economic feasibility of a hydrogen-powered ultra-large cargo aeroplane. This innovative concept aims to revolutionise long-distance freight transportation by offering low air freight rates through economies of scale and unpressurised transport. The aeroplane will have a payload capacity of 1200 tonnes and will require dedicated airport infrastructure. For an integral feasibility assessment, studies were done to determine: potential future demand, airport locations, airport operations & finance, aeroplane production costs, hydrogen production costs and light-weight container supply chain options. Combined these elements were used in a network cost assessment and environmental impact assessment.","Aircraft operations; cargo transportation; demand modelling; project accounting; strategic assessment","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Air Transport and Operations","",""
"uuid:5dd54fa5-b0e4-4d53-9e6d-b91bc4be8b16","http://resolver.tudelft.nl/uuid:5dd54fa5-b0e4-4d53-9e6d-b91bc4be8b16","Performance Analysis and Modelling of Future Integrated Human-Robotic Space Operations","Hosseini, S.","Curran, R. (mentor); Landgraf, M. (mentor)","2016","Pioneering work reinvents the parameters of the possible, and violates the laws of the impossible. Though space exploration is an expanding topic, the future missions to the Moon are the firsts to have humans and automated systems working together to explore new terrains. Preparing the future of human-robotic integrated space operations is a stepping stone for lunar missions, and the current study aims to lead the way towards the next giant leap for mankind. While many studies and experiments focus on the realisation and feasibility of human-robotic activities for space applications, there is a gap in knowledge when it comes to the direct preparation of such operations for near-future lunar missions. In order to prepare such activities the performance of both human and system must be assessed, and this requires either regular highly expensive experiments to obtain performance data, or an innovative and lean assessment approach. The proposed method is the performance analysis and modelling of future integrated human-robotic space operations, using existing data from experiments conducted aboard the International Space Station in which a crew member controls a rover located on Earth. This situation creates the ideal scenario for an analogue experiment above and beyond its original objective. By gathering such experiment data and performing a time analysis of the performance, time estimations are made for a set of tasks and the results can be applied to various scenarios of operations without the skyrocketing cost and crew time. The results of this method demonstrated that it is possible to analyse the time of previous experiments to gain insight on the command time of the human operator and the execution time of the system and that a preliminary tool can be developed to assess the command time and execution time for future operations, based on obtained data from previous experiments. Using the time averages of the data from previous experiments, the gaps are filled of data that was not recorded or incorrectly recorded due to error, under the conditions of the assumption. Expanding on this outcome, it can be implemented to simulate mission specific conditions and results. Using existing parameters, this analysis holds potential to pave the way for the future of experiment preparations such that they in turn prepare the road for future missions to the lunar surface.","Human spaceflight; Human-robotics; Space exploration","en","master thesis","","","","","","","","2021-10-14","Aerospace Engineering","Control and Operations","","","",""
"uuid:19535c16-c7ce-4e1c-8135-9ff6e9f536ce","http://resolver.tudelft.nl/uuid:19535c16-c7ce-4e1c-8135-9ff6e9f536ce","Monin-Obukhov Similarity Theory Applied to Offshore Wind Data: Validation of Models to Estimate the Offshore Wind Speed Profile in the North Sea","Venora, A.","Sathe, A. (mentor)","2009","The wind speed profile in a marine environment is investigated using the data provided from the German offshore research platform FINO-1 and the meteorological mast of the Dutch offshore wind park Egmond aan Zee. The data are compared to the Monin-Obukhov Similarity Theory using the Richardson Bulk Method, the Richardson Gradient Method and the Profile Methods. The results show that the models do not predict the wind speed profile well especially for stable stratifications and large scatter is present. Each model shows different ways to estimate the wind speed profile. The Richardson Bulk Method provides more accurate estimations as compared to other methods and thus it is preferred in further analyses. A sensitivity study is conducted for the model input parameters. The effects of sea surface and air temperatures, coast distance (fetch), reference wind speed and surface boundary layer height are analyzed in terms of mean wind speed estimation and its standard deviation. The model is indeed sensitive to those parameters, especially to air temperature and surface boundary layer height. The use of satellite model database for offshore wind energy purposes is shown in the last part of this work. The weather forecast model COSMO-EU, stored in the database of the Deutscher Wetterdienst DWD, is analyzed consequently and the data are compared with the measurements of FINO-1 for validation. Combinations of real and estimated measurements, respectively from FINO-1 and DWD, are shown for sea surface and air temperatures and relative humidity.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:161f7ec2-29e7-4eca-91ff-d84e40b053a4","http://resolver.tudelft.nl/uuid:161f7ec2-29e7-4eca-91ff-d84e40b053a4","Statistical Impact Prediction of Space Debris: The Uncertainty Propagation Approach","Hoogendoorn, R.","Mooij, E. (mentor); Geul, J. (mentor)","2016","Due to the increasing number of space debris objects in orbit around Earth, the need increases for accurate predictions of impact time and location. These predictions are inherently statistical due to the large number of uncertainties in predicting the atmospheric decay and entry trajectories of these objects. Currently, Monte Carlo methods are used to obtain statistical information about the impact time and location. A direct method is applied to propagate uncertainty in the state of a decaying object to obtain statistical information. This method propagates a PDF of the state in time, instead of single trajectories. Impact time distributions are obtained using this method and Monte Carlo for the Delta-K rocket body.","Atmospheric entry; Uncertainty propagation; Statistical Impact Prediction; Space Debris; PDF propagation; Atmospheric decay","en","master thesis","","","","","","","","2018-01-01","Aerospace Engineering","Astrodynamics & Space Missions","","","",""
"uuid:3f319e5c-437f-4b17-88fc-bdf8bc21e838","http://resolver.tudelft.nl/uuid:3f319e5c-437f-4b17-88fc-bdf8bc21e838","Design of a modular fuselage for commercial aircraft: To cope with seasonal variation in passenger demand","Van Keymeulen, Q.P.D.","Voskuijl, M. (mentor); De Breuker, R. (mentor)","2015","The subject of this research is a new concept of modular aircraft designed to cope with the seasonal variation in passenger demand by opening the fuselage and increasing its length with extra bits of fuselages. The goal is to find out if this new aircraft concept is more profitable than the current alternatives. Previous work have looked at increasing the size of existing aircraft only once in their lifetime. Or offered opening mechanisms for jet fighters or studied modularity for products or Unmanned Aerial Vehicles (UAV). The idea is to design a new aircraft from scratch able to change its size twice a year in order to improve the offer to the passenger demand. The research was performed in four phases by making two tools. The first phase is making the first tool which allows the design of a family of aircraft according to an input network and passenger demand. This is going to serve as basis of comparison for the modular aircraft. The second phase is making the second tool, based on The Initiator, able to design a modular aircraft. The third phase is performing a structural analysis to compute the mass penalty caused by the connection mechanism. The final phase is studying the profitability of the modular aircraft compared to the optimal family form the first phase. This economical study is performed at two levels: the aircraft level and the airline level. The best concept is starting with the long version. Then the short version uses the same wing and tail but smaller engines and landing gear. When using a safety factor of 8 for the connection mechanism, the mass penalty is relatively small ranging from 1 to 6% of the fuselage mass depending on the aircraft configuration. The principal factor driving the performance of the modular aircraft is not the mass penalty but the non-optimal wing used for the short version. To generate the same profitability as the optimal design, the modular aircraft should reach a load factor of 85.6% instead of 80%. Even in a network, the increased fit between the offer and demand cannot outweigh the design penalty. As a result, the potential for a modular aircraft seems low when compared to the alternatives able to increase the aircraft utilization such as real-time-health monitoring of aircraft to improve the maintenance and price-setting algorithms able to improve both the load factor and the profitability.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion (AWEP)","","Flight Performance & Propulsion","",""
"uuid:232e2b1a-95f4-4e2e-910f-4f2f3158cb69","http://resolver.tudelft.nl/uuid:232e2b1a-95f4-4e2e-910f-4f2f3158cb69","The nonlinear effect of combining uncertainties on the energy yield of an offshore wind farm","Engelen, C.M.","Zaaijer, M.B. (mentor); Van Kuik, G.A.M. (mentor)","2015","Offshore wind energy is expected to grow in the coming years: future plans for offshore wind farms total more than 98 GW. Financing is needed to realise these plans. Investment decisions partly depend on the uncertainty in energy yield predictions. It is therefore important that these energy yield predictions and their corresponding uncertainty are determined as accurately as possible. Current methods for determining annual energy production assume that there is a linear relation between input uncertainties and output uncertainty, allowing the use of simple methods for determining annual energy production and its uncertainty. It is however known that this assumption is incorrect: nonlinear relations do exist. This means that it is unclear whether the use of these simple methods can be justified. This thesis has developed a methodology that can be used to determine if, and how, the nonlinear effect of combining two uncertainty sources should be incorporated in the energy yield prediction. This has been done by investigating the case study of the nonlinear effect of combining array efficiency and availability. The investigation was split up in five main steps. First, the physical relations between array efficiency and availability have been explored, revealing that downtime of a turbine affects the array efficiency of a wind farm. Figuring out the state-of-the-art methods pointed out that this interdependency is currently not taken into account. By adjusting the current models, an adapted model was developed that is able to consider this effect. Simulations have been performed on both the current and the adapted model. The results show that for a typical mean availability value of 96.2%, the differences between the current and the adapted model are smaller than 1%. This means that the current methods used by industry can be justified. However, if availability values drop, the difference between both models becomes significant. Due to the high development and computational time of the adapted model, an approximation of the mean annual energy production was developed that uses existing tools. This approximation yields accurate results: the difference between the approximation and the results of the adapted model is lower than 0.5%. Since the approach that was used in this research has proven to be successful, it can be translated to a generic methodology. This methodology can be followed to determine the nonlinear effect of two other uncertainty sources.","Windenergy; array efficiency; availability; nonlinear effect; energy yield; offshore wind; uncertainty","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","","",""
"uuid:89472288-47ae-440c-b1ce-155884617d96","http://resolver.tudelft.nl/uuid:89472288-47ae-440c-b1ce-155884617d96","Reinforcement Learning Guidance for Pinpoint Landing on Mars","Solari, M.","Mooij, E. (mentor); Woicke, S. (mentor)","2017","","","en","master thesis","","","","","","","","2018-07-25","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:8c723c77-3f7c-4ca1-899b-169207c0666a","http://resolver.tudelft.nl/uuid:8c723c77-3f7c-4ca1-899b-169207c0666a","Investigating the Influence of DBD Plasma Actuators on Skin Friction: Application to Integral Boundary Layer Formulation","Bal, S.R.","Balbino Dos Santos Pereira, R. (mentor)","2015","The main driver of developments in the wind energy sector is not the absolute maximization of energy capture, but the reduction of the Cost of Energy (CoE). More and more research is carried out to investigate control of the air flow to reduce fatigue loads, structural requirements, and apply novel control strategies to ultimately reduce this important CoE. Plasma actuators have been the subject of an increasing amount of research in recent years in the field of Active Flow Control (AFC). Of particular interest to the present study is the alternating current Dielectric Barrier Discharge (DBD) plasma actuator, which is widely used due to the low mass, low power consumption, fast response time, absence of moving parts and large actuation bandwidth. Successful applications of the technique include postponement and control of flow separation, transition delay by Tollmien-Schlichting wave cancellation, stream-wise vortex generation and the control of dynamic stall on oscillating airfoils. To fully take advantage of the potential performance increase DBD actuators can offer, its effect should be accounted for as early as possible in the aerodynamic design phase. Previous work at TU Delft incorporated the DBD plasma body force in the integral boundary layer formulations. In the light of discrepancies between the existing model and experimental observations, attention is focused on the skin friction. An experimental campaign was designed and conducted at the open jet facility to acquire high resolution PIV of the turbulent boundary layer during various states of boundary layer development, for both actuated and non-actuated cases. The velocity fields were post-processed to obtain the variation in skin friction induced by the DBD plasma. Major conclusion from the observations is the fact that the increase in skin friction due to actuation occurs downstream of the actual plasma body force region, and extents for approximately 2.6 body force lengths. A semi-elliptical fit is employed to model the variation in skin friction due to DBD plasma actuation dCf . The steps to be taken to implement the dCf in a numerical boundary layer solver are investigated. The work includes a first approach in Matlab, to pave the way for future work to include the skin friction correction in rapid-analysis, viscous-inviscid panel codes based on integral boundary layer formulation such as Rfoil.","Windenergy; skin friction; active flow control; DBD plasma actuation","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","Wind Energy","",""
"uuid:87453335-eeb1-44a0-9f6b-3c840711290a","http://resolver.tudelft.nl/uuid:87453335-eeb1-44a0-9f6b-3c840711290a","Optimising Landing-site Selection for ExoMars","Koenders, R.","Zegers, T.E. (mentor); Vermeersen, B. (mentor)","2009","Only 6 out of 16 missions to the surface of Mars have been successful, all have been NASA missions. The landing sites of all the successful missions have been carefully selected in a process where: 1) scientists propose candidate landing sites, 2) engineers check whether these sites allow for a safe landing, and 3) over a few iterations, the number of sites is brought down to the final site and a back-up. ExoMars will be the first lander to Mars designed by the European Space Agency. It will explore Mars in search of signs of past and present life. An extensive landing-site selection process is required to find a landing site that is safe from both an engineering perspective and that will help to answer the mission’s science objectives. This research has identified four developments that decrease the efficiency of the current landing-site selection process: 1) there is more and more data available on Mars, which makes combining and analysing all this data manually no longer possible; 2) the technical capabilities of the landing system are increasing, which makes a larger part of the surface available; 3) the questions posed in the scientific and exploration objectives become more and more specific, which sets more stringent requirements on where these questions can be answered; and 4) the Martian surface turned out to be more variable in composition than was previously thought. This study recommends a set of improvements in the form of a decision support system (DSS) that assists experts in the landing-site selection process. The DSS developed for this research includes two prototypes 1) a method that emulates the pattern recognition of a trained, terrain-analysis expert (i.e. a geologist) on a computer, called the terrain fingerprinting method (TFM); and 2) a platform that provides the interface through which all stakeholders in the landing site selection process (scientists, engineers, students, managers) can efficiently interact. This study concludes that I) the TFM can be used to find a landing site that optimises both the safety of the mission and the possibility for scientific return at the site. II) A central platform is required in order to empower the landing site selection community by sharing higher level data products, tools (e.g. TFM software tools), a forum, and documentation. III) The United States Geological Survey (USGS) is the central authority in the planetary sciences community in the USA providing standardisation support, the lack of such a central authority in Europe will negatively affect the process of landing-site selection by European scientists for all future planetary landers. And IV) for the various stakeholders to effectively collaborate and interact in the process of landing-site selection, standardisation of elements related to geographically referenced planetary data is essential.","Mars; Decision Support System; Landing-site selection; ExoMars; Solar System Exploration","en","master thesis","","","","","","","","2013-03-07","Aerospace Engineering","Astrodynamics and Satellite Systems","","","",""
"uuid:2ddaef58-3e91-4d52-b5b5-d296dd6a7e79","http://resolver.tudelft.nl/uuid:2ddaef58-3e91-4d52-b5b5-d296dd6a7e79","Improving Global Optimization Methods for Low-Thrust Trajectories","Spaans, C.J.","Mooij, E. (mentor)","2009","Optimization of spacecraft trajectories is an interesting area of research, where a lot of development takes place: in the past years, an optimizer called OPTIDUS was implemented at the chair of Astrodynamics at Delft Univierstiy. This tool is able to do optimization of spacecraft trajectories (and other problems) using an evolutionary algorithm. However, there are other optimization algorithms available which (according to literature) also perform well on trajectory optimizations. These are Particle Swarm Optimization (PSO) and Differential Evolution (DE). For this thesis, a new version of OPTIDUS has been implemented, which not only supports evolutionary algorithms, but also several variants of differential evolution and particle swarm optimization. These algorithms are also implemented in a way that can exploit the availability of multiple processing cores in a computer, which can give a very good improvement in the runtime of optimizations. Also, a local optimizer using Powell's quadratically convergent method has been implemented. This new version of OPTIDUS is benchmarked against several PSO implementations, and it is found that performance on several (mathematical) testing functions is comparable to existing implementations. However, it is not possible to appoint DE or PSO as the best algorithm in general, as that is problem dependent. The software is also applied to improve the optimization of a Solar polar sailing mission. By comparing the number of function evaluations and the best fitness value found for a family of optimizers (several variants of PPO and DE and an EA), it is found that DE gives the best results, giving an reduction in mission cost almost 4% compared to the original result found using an EA. The use of a local optimizer on this best result is able to improve it even further by another 0.15%. Finally, this software is used to find a solution to the GTOC3 problem, where the goal is to find a low-thrust trajectory for a spacecraft to rendezvous with several asteroids. The hard part of this mission are the rendezvous constraints: upon arrival at an asteroid, the location and velocity of the spacecraft relative to the asteroids have very low margins, making a very large part of the solution space infeasible. For that reason, an augmented objective function which takes these violations into account is used. Both an augmentive function in the form of a weighted sum (of violations) and a multi-objective function are considered. The multi-objective variants gives better results, but is not compatible with the local optimizer, Powell's method. Only the first part of the mission, from Earth to the first asteroid, is optimized. Using DE, a solution is found, which almost satisfies the constraints, but not completely. By applying Powell's method to this solution, the constraint violations are further reduced, but still a small violation of the position remains. It is found that doing global optimization using DE can generate solutions with quite large constraint violations, but that subsequent application of a local optimizer can reduce those violations, while not changing the solution considerably. How the solution of this first leg compares to solutions by other teams is not known, as the per-leg results have not been published.","Differential Evolution; Particle Swarm Optimization; Evolutionary Optimization; Spacecraft Trajectories; Orbit Optimization; Global Optimization; GTOC3; Solar Sailing; OpenMP; Optidus","en","master thesis","","","","","","","","2009-08-28","Aerospace Engineering","Astrodynamics and Satellite Systems","","","",""
"uuid:cef6b8a3-b7e0-4a86-932f-e35027091bb8","http://resolver.tudelft.nl/uuid:cef6b8a3-b7e0-4a86-932f-e35027091bb8","Power Modelling and Optimisation of a Communication bus for Small Satellite Missions","Orsel, E.G.A.","Guo, J. (mentor); Carvajal Godinez, J. (mentor)","2016","","","en","master thesis","","","","","","","","2016-12-31","Aerospace Engineering","Space Engineering","","","",""
"uuid:5dc275ca-cdfb-4104-bec8-2d1665cd04a5","http://resolver.tudelft.nl/uuid:5dc275ca-cdfb-4104-bec8-2d1665cd04a5","Design of Convex Guidance for the Final Phase of Satellite Rendezvous: Tested using Hardware-in-the-Loop Simulations","Vromen, S.S.","Mooij, E. (mentor)","2015","Over the past decades the steep increase in the number of space-debris objects have sparked many studies into active space-debris removal. Past collisions have shown that space debris is a very real threat to operational satellites and active debris removal is necessary to stabilize the situation. ESA has, therefore, performed multiple studies on the removal of the no longer operational satellite ENVISAT from orbit. Since ENVISAT lost functionality, it has acquired a tumbling motion, which poses many challenges for a removal mission. A scenario was proposed in which a chaser spacecraft performs a rendezvous with ENVISAT, to actively de-orbit the satellite. To increase the robustness to unexpected events and reduce operational costs it is highly desirable that these operations can be performed autonomously. In this research an autonomous guidance and orbit control system was developed that enables the final phase of the rendezvous with ENVISAT. An approach strategy was adopted that aims to maintain alignment with the spin axis of ENVISAT throughout the approach. The designed algorithms use convex guidance to ensure globally-optimal solutions, while at the same time constraining the trajectory. The guidance algorithm minimizes a weighed combination of the thrust and the state error. Furthermore, the concept of model predictive control is applied to allow for an unconstrained time-to-go. Two guidance and control strategies were examined in this research, one that is solely based on model predictive control and another that employs an additional LQR-controller. The functional simulations were complemented by hardware-in-the-loop simulations using the DLR flat-floor test facility, TEAMS. These real-time tests also include the docking phase. Both the functional and hardware-in-the-loop simulation results show that the baseline model predictive control method can successfully perform the operations with an accuracy well above the requirement. It was found that implementing an extra LQR controller resulted in a similar accuracy, but an increase in mission propellant of 21%. The functional simulation results also revealed that the required mission propellant, compared to the baseline, could be decreased further by 18%, while maintaining the baseline accuracy. This is achieved by optimizing the weight parameters used in the convex optimization. It does, however, lead to an increased mission duration. The designed algorithms were successfully implemented on TEAMS, where it was shown that the addition of an LQR controller again leads to a higher use of propellant and on top of that it results in a longer operation time.","Rendezvous; Hardware-In-The-Loop; Guidance; Convex","en","master thesis","","","","","","","","","Aerospace Engineering","Spaceflight","","Space Exploration","",""
"uuid:437869ae-2a7d-40aa-b809-67b314dc91a7","http://resolver.tudelft.nl/uuid:437869ae-2a7d-40aa-b809-67b314dc91a7","Electrodynamic Tether Experiment onboard the Delfi-1 Satellite","Wijnans, A.S.","Zandbergen, B.T.C. (mentor)","2012","Space debris is becoming an increasing problem requiring a low cost propulsion system capable of disposing non operable satellites and spent rocket stages. To this end electrodynamic tethers have been proposed as a viable alternative to conventional propulsion. Aside from a de-orbit system electrodynamic tethers have a wide range of applications as a power generator or propulsion system being ideally suited to orbital environments having strong magnetic fields for example Jovian orbits. Previous experiments performed in the development of electrodynamic tethers used insulated wire tethers and separate current collection devices, either large passive spheres or active plasma contactors. The subject of this thesis is to design and size an electrodynamic tether experiment for use onboard the Delfi-1 University satellite. The main objectives of the experiment are to provide a proof of concept of bare electrodynamic tether propulsion and deploy and operate a tape tether. A tape tether design has been selected having a favourable geometry for current collection and survivability in the micrometeoroid and orbital debris environment in comparison with ‘traditional’ wire tethers. The tape tether also has favourable drag properties allowing for a rapid deorbit when cut from the main satellite decreasing the risk of collision with operational satellites. A secondary objective for the experiment is to determine if the release of a neutral gas can enhance the current of the tether and the deorbit performance. This experiment is fundamental in the development of a fully passive deboost capability for tether equipped systems. The limited amount of storage and mass, power and data rate available when using a micro-satellite platform for the experiment combined with low complexity and cost requirements inherent to the Delfi-1 project drives the design to a bare minimum required for performing the primary scientific objectives. The baseline design for the experiment is characterised by a passive bare floating electrodynamic tether deployed in nadir direction using a passive deployment mechanism.","electrodynamic; tether; propulsion","en","master thesis","","","","","","","","2012-03-08","Aerospace Engineering","Space Engineering","","Space Systems Engineering","",""
"uuid:f6e08f87-267c-4a79-a6cb-72494a859145","http://resolver.tudelft.nl/uuid:f6e08f87-267c-4a79-a6cb-72494a859145","Effects of Structural Failures on the Safe Flight Envelope of Aircraft: A database approach to ight envelope prediction and protection","Nabi, H.N.","de Visser, C.C. (mentor)","2016","","","en","master thesis","","","","","","","","2021-08-31","Aerospace Engineering","Control and Operations","","Control & Simulation","",""
"uuid:0e795e6d-ddc8-4710-b92a-adf1ee3cbdd7","http://resolver.tudelft.nl/uuid:0e795e6d-ddc8-4710-b92a-adf1ee3cbdd7","Aeroelastic analysis of a 3D wing structure with a flexible trailing edge","Lonsain, J.","De Breuker, R. (mentor); Sodja, J. (mentor)","2017","Aeroelastic analyses traditionally consider the airfoil of a wing to remain rigid, only allowing deformation in the span-wise direction of the wing. Recent investigations have shown the benefits of adding chord-wise flexibility in the trailing edge of a wing, however so far only two-dimensional studies have been carried out. Therefore, the investigation presented here determines whether chord-wise flexibility in the trailing edge improves aeroelastic behaviour for three-dimensional wing structures as well. To determine whether chord-wise flexibility improves the aeroelastic characteristics, a dynamic aeroelastic state-space model is built to compute the flow velocity at which the wing structure becomes instable and a closely coupled static model to compute the steady aerodynamic loads. Linear Timoshenko beam finite elements are used to represent the wing-box structure and are part of the existing aeroelastic framework PROTEUS, which is developed at the TU Delft. Linear flat shell elements are used to model the structure of the flexible trailing edge and rigid links couple these elements to the wing-box structure. The aerodynamic model in PROTEUS is modified in such a way that individual panel forces are extracted and trailing edge deformation can be transferred to these panels. By varying the thickness of a quasi-isotropic carbon fibre laminate in the trailing edge, its flexibility is managed. It was found that increasing the flexibility of the trailing edge increases the flutter speed of the wing in a similar manner as with a 2D typical section. A difference with a 2D typical section is that in the region of plate flutter, mode jumps occur due to span-wise deflection of the wing-box. If only part of the wing in span-wise direction is equipped with a flexible trailing edge, the flutter speed can be increased more effectively by positioning it towards the tip of the wing. The downside of increased trailing edge flexibility is the reduction in steady lift generated by such a wing.","Aeroelasticity; Chord-wise flexibility; Finite element model; Plate elements; Vortex-lattice method; State-space system","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:74f497b8-26f9-4600-804a-9219456a4286","http://resolver.tudelft.nl/uuid:74f497b8-26f9-4600-804a-9219456a4286","Modeling the dynamics of a spar-type floating offshore wind turbine","Savenije, L.B.","Ashuri, T. (mentor); De Beer, E. (mentor); Staerdahl, J.W. (mentor); De Koning Gans, H.J. (mentor); Van Bussel, G.J.W. (mentor)","2009","The installation of floating wind farms in deeper water is encouraged by the stronger and steadier wind, the lower visibility and noise impact, the absence of road restrictions, but also the absence or shortage of shallow water. In the summer of 2009, the first large-scale floating wind turbine ""Hywind"" was installed. Hywind is a spar-buoy concept with three catenary mooring lines. Offshore floating wind turbines are a completely novel concept. The experience with modeling such turbines is still limited. A new basic model has been developed for a spar-type floating wind turbine. The requirement of the model is that it incorporates the most significant physical processes so as to be able to provide insight into the dominant physical behaviour of spar-type floating wind turbines. Various verification methods show that A.T.FLOW simulates load cases as expected and is a useful tool for assessing the physical behaviour of spar-type floating wind turbines. The coming two years the body forces and behaviour of the operating full-scale Hywind demo project is monitored. This data should be used to further test and validate A.T.FLOW and to guide further development of the model.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","","",""
"uuid:a71d1a2f-4a0b-4c48-8fb4-adef8fa519be","http://resolver.tudelft.nl/uuid:a71d1a2f-4a0b-4c48-8fb4-adef8fa519be","Aeroelastic Roll Control for High Aspect Ratio Wings","Van Emden, J.","Vos, R. (mentor)","2013","Modern aircraft tend to be light and slender. The high aspect ratio reduces the induced drag, increase fuel efficiency, and provide enough lift a low speeds. Therefore such wing types are used for long endurance unmanned aerial vehicles (UAV). A drawback of these wings is that they are more vulnerable for aeroelastic phenomena like divergence, aileron reversal, and flutter. To increase the dynamic pressure, at which one of these phenomena occurs, the stiffness of the wing needs to be increased leading to an increase of the wing weight. Instead of increasing the wing weight, the flexibility of the wing can be used to change the shape of the wing to optimize flight performance or to control the rolling motion of the aircraft. This research area of Active Aeroelastic Wings has grown in the recent years. With this concept, very little control surface motion is used to employ the energy of the airstream to achieve the desirable wing twist. In this thesis work, an Active Aeroelastic Wing is designed, built and tested in a low-speed wind tunnel. After testing, the possibility to predict the performance accurately with a state-of-the-art modeling tool is verified. First, a qualitative background overview is given about the three most important aeroelastic phenomena. These phenomena are torsional divergence, control reversal, and classical flutter and are described to understand the effects of the different wing parameters on the deformations. Secondly, an overview is given of the techniques that have been used to change the shape of the wing. From these concepts, the sweepable spar method has been chosen. This method uses the ability to change the position of the elastic axis, so that the twist deformations can be increased or decreased. Based on this method, a test article has been built that has similar planform shape as the Global Hawk. Instead of ailerons for roll control, the test article is equipped with an aeroelastic outer wing segment that can change its elastic axis. With this aeroelastic outer wing part, the wing is able to provide a rolling moment. Afterwards, its performance has been tested in the Open Jet Facility of the TU Delft. The results of the bench tests showed that the moveable spar is able to change the position of the elastic center at the wing tip. With the main spar at different positions, a change in the torsional stiffness of the wing has been observed. During the wind tunnel test the influence of the sweep angle on the rolling moment has been analyzed. The results did not clearly indicate a beneficial effect of the sweep angle on the rolling moment coefficient. Therefore the wing configuration is set to sweep angle of zero degrees to continue the testing. For this configuration, the main spar moved aft on the left and forward on the right wing, the maximum achievable roll helix angle is similar to that of a Boeing 747-200 during cruise. However, the roll performance of the Global Hawk is about five times larger than the test article. Note that aeroelastic effects have been neglected for the Global Hawk, which reduces the aileron control effectiveness. Finally, the results of the wind tunnel experiments are compared with the simulation results of Proteus. Proteus is an analysis and design framework that uses a non-linear beam model combined with lifting line theory to determine the aeroelastic effects. To analyze the test article some structural and aerodynamic modifications have been made in Proteus, to integrate the effects of a sweepable elastic axis and cambered airfoils. With these modifications the predicted rolling moment coefficient was about 40% smaller compared to the wind tunnel results. Therefore it is concluded that Proteus is currently not able to predict the results accurately.","Aeroelasticity; Active Aeroelastic Wing; Roll Control","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:84982b5a-2566-4cc3-a410-2cfd2e3b96f3","http://resolver.tudelft.nl/uuid:84982b5a-2566-4cc3-a410-2cfd2e3b96f3","Use of Anionic Polyamide-6 Composites in Oil and Gas Pipeline Environment","Wang, L.","Bersee, H.E.N. (mentor)","2016","","APA-6; thermoplastic composites; environmental deterioration","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","Structural Integrity and Composites","",""
"uuid:87fc31f2-4a04-4a08-bf5c-7ecedca96195","http://resolver.tudelft.nl/uuid:87fc31f2-4a04-4a08-bf5c-7ecedca96195","Optimising Ultrasonic Welding of Carbon Fibre PEKK Composites","Broek, C.A.","Villegas Fernandez, I. (mentor); Palardy, G. (mentor)","2015","The interest of the aerospace industry in thermoplastic composites has increased over the last years. One of the advantages of using thermoplastics over thermosets is the possibility to use thermoplastic welding as a joining technique. Ultrasonic welding is considered one of the most promising variants: it is very fast, results in high-quality welds, can be applied to any fibre and resin type, is easy to automate and makes use of compact tooling. Therefore, it is a suitable technique for assembly and spot welding. This thesis research aims to improve the current processes for ultrasonic welding at TU Delft, while keeping a close eye on the industrial application. The first part of the research was focussed on the energy directors (EDs): resin protrusions between the substrates that heat up before the bulk material in the laminates. Previous research at TU Delft has mostly used loose EDs, but for industrial purposes it is preferable to integrate the EDs into the laminates. In this research, two production methods were developed that are suitable for moulding slender ED strips onto laminates: the first with aluminium strips with holes, the second with an Invar mould in which slender grooves have been machined. Both were used in combination with neat PEKK foil. An issue that was encountered with both methods is the variability in the thickness of the strips, leading to uneven melting. A comparison was made between the welding process of integrated and loose EDs. Moreover, it was found that the loose energy directors outperformed the integrated energy directors in terms of joint strength. Next, the displacement ceiling was investigated: a maximum in sonotrode travel that occurs before the optimum weld stage has been reached. When this happens, it is more difficult to use displacement as a welding driver to create welds of high strength. It was found that there are two types of displacement ceiling. The first occurs when a single ED strip is used, or the strips are placed far apart and the flow fronts do not merge. The origin possibly lies in changes in impedance and friction of the energy director flow. The second type of ceiling occurs when multiple ED strips flow and merge, which only happens if the spacing between them is small enough. The flow of the EDs pushes into each other, increasing the impedance of the flow and preventing further displacement of the sonotrode. To overcome the displacement ceiling, new displacement-controlled welding strategies have been investigated. First, the vibration phase was stopped before the ceiling had been reached. This resulted in welds of poor quality and strength. By reducing the pressure, the welds could be improved, but not to a satisfactory level. In the second strategy, the welding pressure was increased during the vibration phase. It was found that it is possible to push through the displacement ceiling and use a higher displacement value as the welding driver, which improves the strength of the welds greatly. These results showed significant scatter in the strength, which could be reduced by preventing secondary welding.","ultrasonic welding; thermoplastic composites; carbon fibre pekk; energy directors","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","Structural Integrity and Composites","",""
"uuid:a2b6f58f-db23-45ea-952e-5092c21dded9","http://resolver.tudelft.nl/uuid:a2b6f58f-db23-45ea-952e-5092c21dded9","Compression Strength of Wrinkled Composite Laminates","Manikarnika, K.","Kassapoglou, C. (mentor)","2016","MSc degree in Wind Energy at DTU in Denmark, and MSc degree in Aerospace Engineering at TU Delft in the Netherlands - Wrinkle defects are prevalent in wind turbine blades and are a leading cause of blade failure. Accurate modeling of the compression strength of wrinkled composite laminates is needed by manufacturers. Based on the creation of a parametric nite element model of a through-thickness wrinkle defect, along with a series of geometric and material parameter studies, this research seeks to determine the compressive strength of various kinds of wrinkled composite laminates. A 2D FE model of alternating layers of elastic-plastic matrix and elastic orthotropic ber laminae is used. Plastic microbuckling (kinking) strength is given by the limit load, while delamination strength is determined from a maximum shear stress criterion. The main conclusion is that compression strength of a wrinkled laminate is strongly dependent on the maximum initial fiber misalignment angle. There is also strong sensitivity to the height to length ratio. Furthermore it is found that higher matrix yield strength increases compression strength. Finally, it is found that in hybrid wrinkles, an increasing amount of carbon increases the compression strength.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","European Wind Energy Master (EWEM)","",""
"uuid:d1c2ae57-b44e-4c3e-b408-57315063c306","http://resolver.tudelft.nl/uuid:d1c2ae57-b44e-4c3e-b408-57315063c306","Initial development of an expert system for support and wall interference","Sons, D.","Veldhuis, L.L.M. (mentor)","2010","Over the years a lot of knowledge about support and wall interference in wind tunnel experiments has been gained. Unfortunately this knowledge is only represented by a relatively small number of specialized wind tunnel staff. A computer system that can store interference data in an organized manner can be a valuable addition to human expertise. Such a system can be used to make this knowledge more readily available for not necessarily specialized staff and to further increase the understanding of support interference in particular. In this thesis the initial development of such a system is described: The Expert system for Support and Wall Interference ESWI. ESWI will be developed in cooperation with German Dutch Windtunnels DNW and will focus initially on data obtained from the Large Low speed Facility LLF located at DNW headquarters in Marknesse, Netherlands. ESWI will consist of a number of separate modules. The first version of ESWI will consist of its first module named Advice Sting And Position ASAP. This module consist of a database part and a numerical part.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:dbf7edcf-5d2a-420d-8517-ae36359e1346","http://resolver.tudelft.nl/uuid:dbf7edcf-5d2a-420d-8517-ae36359e1346","Ice-Induced Aircraft Stability Upsets: An experimental investigation to identify linear and non-linear fluid-structure lock-in","Baars, W.J.","Scarano, F. (mentor)","2009","Research related to the impact that war head induced damage had on the aeroelastic integrity of lifting surfaces and in turn the resulting upset of the complete aircraft, prompted a current look at similar aeroelastic events that might be triggered by damage of the aircraft due to icing. This possible aeroelastic impact due to icing damage is not a very commonly explored area of research. Although seldom studied, icing can also significantly impact the aeroelastic stability and hence the overall stability and control of the aircraft. In this latter context, classical flutter events of the lifting surfaces and controls can occur due to ice-induced mass unbalance or control force reversal. Also, a loss of control effectiveness or limit cycle oscillations of the controls and lifting surfaces may appear, due to significant time dependent drag forces introduced by separated flow conditions imposed by the ice accumulation. Two commonly observed ice-induced upset scenarios were selected to investigate. The first scenario involves an elevator limit cycle oscillation and a resulting loss of elevator control effectiveness. The second upset is related to a violent wing rock or Dutch roll instability. In both proposed ice-induced upsets, lock-in mechanisms of two unsteady events occur, (1) the ice-induced unsteady flow field and (2) the unsteady structural acceleration of the aircraft. A wind tunnel study is employed to investigate the lock-in mechanisms of the structural acceleration and the unsteady flow field induced by ice accumulation that is only present on the elevator horn balance leading edges. The purpose is to determine the linear and non-linear coupling mechanisms between these events. An experimental data set has been obtained where the unsteady, ice-induced, flow field and the acceleration of a 1:10 scale, reduced-stiffness, aircraft model is synchronously acquired using pressure transducers and accelerometers, respectively. The experiments are performed at various angles of attack of the aircraft, _p, with and without simulated ice accumulation on the elevator horn balance leading edges and with various settings of the elevator deflection angle, _. Statistical signal processing techniques, that are able to compute linear and quadratic coherence spectra, are presented in this thesis work and are applied in the pressure-acceleration coherence study. The first-order processing technique, based on the well-known linear coherence spectrum, revealed a low-frequency lock-in (f = 6Hz, _p > 7_) for the case where ice accumulation was simulated on the leading edges of the horn balances, while no lock-in was observed without ice simulations. This indicates that violent aircraft motions can indeed be a result from the ice-induced flow field over the horn balances. Although a reduced-stiffness aircraft model was used in the experimental setup, and thus the quantitative results are not translatable to the full-scale case, the identification of this linear lock-in mechanism indicates that their is a significant chance that similar lock-in mechanisms occur in full-scale flight applications. An attempt to identify the quadratic relations between the two unsteady systems was performed by employing higher-order statistical signal processing based on a non-orthogonal, secondorder, single-input/output (I/O) Volterra model. Due to current limitations, related to the implementation of this technique, no physical interpretations could be done based on the higher-order coherences. Recommendations are given to improve the identification capability of this higher-order technique, which might become a powerful identification and estimation tool in (experimental) fluid dynamics.","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:de09f6fc-3bc0-4aa8-8d33-dbe3a89ef4b3","http://resolver.tudelft.nl/uuid:de09f6fc-3bc0-4aa8-8d33-dbe3a89ef4b3","Development of a Life Cycle Cost Model for Conventional and Unconventional Aircraft","Zijp, S.O.L.","Vos, R. (mentor)","2014","","Cost Engineering; unconventional aircraft; conceptual design phase; life cycle costing; parametric analysis; non-communality factor","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance & Propulsion","","","",""
"uuid:faf02585-82a4-4126-a84a-9fccbbbc7eec","http://resolver.tudelft.nl/uuid:faf02585-82a4-4126-a84a-9fccbbbc7eec","Simulator motion cueing error detection using a wavelet-based algorithm","van Leeuwen, T.D.","Pool, D.M. (mentor); Cleij, D. (mentor); Mulder, M. (mentor); Bülthoff, H.H. (mentor)","2017","Understanding the process of human motion perception is essential for optimizing the motion cueing algorithms (MCAs) used by motion simulators. Previous research has shown that different motion cueing error types can be distinguished, at least some of which are rated differently by humans for equal error magnitude. Optimizing a motion simulation for both error magnitude and error type requires a method to objectively identify the presence of different motion cueing error types from simulation input and output traces. This paper presents a wavelet-based motion cueing error detection algorithm that exploits the time and frequency characteristics of these error types. A simulator experiment is presented through which parameters of the algorithm are determined. It is shown that motion cueing errors can be detected by the algorithm without prior knowledge of the MCA used. The need for the algorithm is demonstrated by showing that motion cueing error types can be divided in clusters of severity. Additionally, it is shown that in curve driving, given a reference of unity gain, the lateral specific force can be scaled down to 70% and up to at least 130% before subjects indicate motion to be too weak or too strong. A required input and output coherence of 0.7 is found for simulator input and output to be considered coherent. The motion cueing error detection algorithm can be used to improve motion cueing algorithms in the future.","Motion simulation; motion cueing; motion perception; error detection; algorithm; wavelets","en","master thesis","","","","","","","","2022-01-01","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:cd070b5f-c71d-44d1-bff9-46421b0d00ba","http://resolver.tudelft.nl/uuid:cd070b5f-c71d-44d1-bff9-46421b0d00ba","Field-test of nacelle-based lidar to explore its applications for Vattenfall as wind park operator","Goossens, S.J.","Van Bussel, G.J.W. (mentor); Bierbooms, W.A.A.M. (mentor); Coelingh, J.P. (mentor)","2015","The market share of wind energy is related to many factors, including politics, social acceptance and financial feasibility. In light of reducing the Levelised Energy Cost (LEC) generated from wind energy, power company Vattenfall is continuously looking for new ways of monitoring and improving wind turbine yield. Recent publications have shown nacelle-based lidar to be a valuable tool for research, capturing the interest of Vattenfall's Wind Resource team. To gain more insight in the applications of nacelle-based lidar and their benefits to Vattenfall as operator, a measurement campaign was conducted at wind park Slufterdam West. More specifically, a Wind Iris was installed on the nacelle of the most southern wind turbine (type GE 1.5s) and a sodar of type AQ500 was installed 235m to the southeast of this turbine. The Wind Iris proved to be a useful instrument for measurement of the power curve and mean yaw misalignment. The former was found to be in accordance with the contracted power curve and the latter turned out to be 1.5 degrees. In the wind regime where it is most relevant to the power curve (4-13 m/s), yaw misalignment was found to have no clear relationship with rotor speed and wind speed. Two methods were used to investigate the impact of yaw misalignment on the power curve, but no definitive conclusions could be drawn. Moreover, the Wind Iris was found to be a useful tool for investigating the blockage effect and results were in accordance with theory. Finally, a financial case study was carried out to evaluate implementation of the Wind Iris at Slufterdam. However, since there is no evidence that the turbines have yaw misalignment nor that small yaw misalignment is harming the power curve, implementation is currently not recommended. However, if the impact of yaw misalignment on the power curve can be quantified accurately, implementation can be financially viable.","yaw misalignment; power curve; blockage; nacelle-based lidar; Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","Wind Energy","",""
"uuid:99edc128-9545-4aad-99ad-13836f337d3e","http://resolver.tudelft.nl/uuid:99edc128-9545-4aad-99ad-13836f337d3e","Unsteady Aerodynamics in the Gust and Manoeuvre Response of Flexible Aircraft","Westerveld, D.","Voskuijl, M. (mentor)","2016","Aircraft wings are becoming more flexible, making it important to take this flexibility into account from the start of the design process. With flexible wings, unsteady (time-varying) aerodynamics becomes important. For this reason, an unsteady aerodynamics model was constructed and coupled to an aeroelastic flight mechanics tool. This allows for investigating the response of the aircraft after gusts or control inputs. It was found that for wings of relatively high stiffness, unsteady aerodynamics is not important to take into account during gust response modelling. The difference between unsteady and steady aerodynamics was found to not be more that 5%. The short period motion is influenced significantly by the unsteady aerodynamics, with a change in period of 18%. Results have also indicated that unsteady aerodynamics is more important for more flexible wings. The current work allows for simulating these more flexible wings, in both longitudinal and lateral situations.","aeroelasticity; unsteady vortex lattice method; unsteady aerodynamics; flight dynamics; gusts","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:ff977688-ead7-4c1a-b595-49e7626089bf","http://resolver.tudelft.nl/uuid:ff977688-ead7-4c1a-b595-49e7626089bf","Accuracy Assesment of direct sensor orientation in UAV Photogrammetry","Stam, J.","Koshelham, K. (mentor)","2011","With the advent of Unmanned Aerial Vehicles, it becomes possible to use these vehicles to acquire photogrammetric images in a more cheap and flexible way compared with conventional photogrammetry from a full-sized airplane. A big factor in costs and resources in conventional photogrammetry is signalling and measuring ground control points, which are necessary to determine the location and attitude of the photos. Eliminating the need for ground control points would make the photogrammetric process much less costly and labour intensive. A UAV contains navigational sensors (a GPS receiver and a Inertial Measurement Unit) for it's own navigation. The output of these sensors can also be used for the orientation of the photographs. However, the accuracy of these sensors, especially low cost off-the-shelf sensors, is limited. This thesis concentrates on determining the accuracy of low-cost navigational sensors and the effect of inaccuracies in these sensors on the result of the photogrammetric product: a Digital Terrain Model. Using a UAV developed by the company Heering UAS, founded by Pieter Wijkstra, the effects of inaccuracies in the GPS receiver and the IMU in the UAV on the outcoming Digital Elevation model has been tested. First the theoretical effects of inaccuracies of navigation sensors on the final product is investigated, using the photogrammetric collinearity equations. To validate the theoretical results, a number of tests has been carried out using an available platform with an off-the-shelf camera and dito navigation sensors. A first test, using flight data and photos taken at the unfinished A4 highway site just south of Delft, shows the sensitivity of the final model to errors in the navigational sensors. This test did not give enough data though to give enough insight in the effects of navigational sensor errors. Therefore a second test was carried out using a larger photoblock flown at the dyke of the river Lek at Ammerstol. This test showed that the errors in the terrain model caused by errors in the on-board GPS receiver follow the results of the theoretical simulation. However, because at the time, the UAV did not contain a reliable IMU, the effect of IMU errors could not be tested. So a third test was conducted, using an off-the-shelf IMU combined with a high accuracy GPS receiver to asses the effect of errors in the IMU on the resulting terrain model. The results show that off-the-shelf navigation sensors are not accurate enough to produce a reliable end result. Therefore eliminating ground control points would result in a final product which is not accurate enough. Using the available navigation sensors it is possible to reduce the amount of ground control points.","UAV; photogrammetry; accuracy; GPS; Inertial Measurement Unit","en","master thesis","","","","","","","","","Aerospace Engineering","Optical and Acoustic Remote Sensing","","Msc Geomatics","",""
"uuid:bbda3bdf-b32c-4109-9d48-02d6f494aa6e","http://resolver.tudelft.nl/uuid:bbda3bdf-b32c-4109-9d48-02d6f494aa6e","Determining loads over a 3D HAWT blade making use of PIV data","Marelli, M.","van Bussel, G.J.W. (mentor); Simao Ferreira, C.J. (mentor)","2010","","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","","",""
"uuid:4d1818ec-5842-47b0-b144-173aa77a3803","http://resolver.tudelft.nl/uuid:4d1818ec-5842-47b0-b144-173aa77a3803","Business Jet Design Using Laminar Flow","Boersma, J.Y.","Veldhuis, L.L.M. (mentor)","2016","For conceptual aircraft design to include accurate laminar flow prediction, a link between modern computational tools to determine laminar-to-turbulent boundary layer transition and fast sizing methods is required. For swept wings, it is crucial to include the highly unstable three-dimensional crossflow component of the boundary layer. These topics were connected to judge the impact of laminar flow on business jets, deemed suitable for laminar design considering their relatively low Reynolds number compared to commercial transport.","drag; N-factor; boundary layer; skin friction; laminar; flow; transition; Reynolds; crossflow; aircraft; design; business; swept; wing; initiator; model","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Flight Performance & Propulsion","",""
"uuid:82c6b30c-768c-46d7-bbdd-ccc086e8c28b","http://resolver.tudelft.nl/uuid:82c6b30c-768c-46d7-bbdd-ccc086e8c28b","Aerodynamic optimisation and thermal loss modelling of a radial micro turbine","Subramani, K.","Pini, M. (mentor)","2016","Micro turbines are miniaturised gas turbines and have the potential to be effectively used in combined heat and power (CHP) applications due to their advantages over reciprocating engines. Micro Turbine Technology B.V. is developing a 3kW recuperated micro turbine for a micro-CHP application and is currently looking for ways to improve the efficiency of the system. At present, off-the-shelf turbocharger components are used to reduce costs and there is a scope for improvement by shifting to a bespoke design. With the reduction in the size of the turbine, the volume-to-surface ratio decreases and hence the heat transfer effects become important. The decrease in performance due to thermal losses needs to be evaluated in order to make an accurate prediction of the efficiency of the turbine. In this thesis, a numerical model is developed for estimating the heat lost to the environment and to the bearing housing using a lumped analysis method. This is coupled to a CFD simulation of the volute and the rotor to provide a diabatic boundary condition for the solver. The results from the thermal loss model are compared with existing data from MTT and it was found that the model can predict the thermal losses with good accuracy. To improve the efficiency of the rotor, a 3-D shape optimisation is performed using the tools in ANSYS suite. To ensure that the new design can be directly used in the system, system-level parameters like shaft speed and mass flow rate are constrained. The important geometric parameters are parametrised and a response surface optimisation is set-up. A lower-order model of the design space is built and due to the large number of input parameters, a significant number of refinement points are added to ensure good accuracy of the response surface. In the next stage, a two-step optimisation is executed. Gradient based optimisers are computationally less expensive, but are prone to converging at local optimum values. This drawback can be overcome using evolutionary algorithms, but they require more computational time to converge. Therefore, an evolutionary algorithm with a relatively relaxed constraint is used to identify the location of the global optimum and a gradient-based search is performed in this confined design space to accurately identify the optimum design point. The influence of thermal losses in determining the optimised design is also evaluated. From the results, it was seen that the optimum point does not change significantly when the thermal losses are included and hence it can be inferred that the thermal loss evaluation can be decoupled from the optimisation process. An improvement of 2.17 percentage points in efficiency is achieved through the optimisation while respecting the mass flow rate constraint and also imposing a limit on the leading edge hub radius to ensure the stresses do not exceed permissible levels. However, when the limit on the leading edge radius is removed, the efficiency increased by 5.36 percentage points. Based on a detailed study of the optimised geometries, it was seen that the blade angle distribution and the leading edge hub radius are the most important parameters influencing the efficiency of the rotor. The blade widths at the inlet and exit can be used to control the mass flow rate in the system and compensate for any change in mass flow rate that is caused due to the variation of the other parameters. The influence of the trailing edge sweep on the efficiency is also studied and it was seen that effect of the sweep angle is strongly influenced by the shroud blade angle distribution. The future work based on this thesis can be directed towards including a structural solver inside the optimisation loop to ensure that the optimiser also consider the stress constraints that need to be satisfied for a feasible design. Also, it was clear that the inflow angles are not at the optimum value and hence a re-design of the volute is suggested to reduce the incidence losses.","CFD; micro turbine; thermal losses; optimisation; lumped analysis","en","master thesis","","","","","","","","2021-12-21","Aerospace Engineering","","","","",""
"uuid:deb7f375-e5ae-4711-8b1f-41153444d5b5","http://resolver.tudelft.nl/uuid:deb7f375-e5ae-4711-8b1f-41153444d5b5","Semi-analytical solutions for buckling and post-buckling of composite plates: Application to stiffened Panels","Cabot Talens, E.","Kassapoglou, K. (mentor)","2016","This MSc thesis addresses the study of buckling and post-buckling of composite plates with elastic restraints at the edges and under any combination of in-plane loading, aiming to solve the plate response in stiffened panel structures. The implemented solutions are based on thin plate theory for mid-plane symmetric plates. The governing equations are solved using a semi-analytical formulation (not closed form) to combine advantages from analytical and numerical analysis. This approach allows to solve most of the typical laminates used in aerospace applications while allowing an improved performance when compared to FE models. The developed formulation relies on eigenbeam functions to approximate the plate behaviour for any combination of arbitrary elastic restrains, with a minimum number of degrees of freedom. This approach has proved to be able to reproduce the buckling mode and load for buckling and the out-of-plane displacement for post-buckling. The results obtained have been verified against FE commercial software package Abaqus and good to excellent agreement has been achieved using a fraction of the computational power. The relation between the ideal torsional springs and stiffeners’ restrain is approximated in order to apply the developed formulations to more practical problems involving stiffened panels. Preliminary verifications show the validity of the proposed approaches and encourages the further development of the solution to achieve a more powerful stiffened panel formulation. Moreover, the developed approaches can be extended to solve other relevant stability phenomena such as global buckling or stiffener crippling. This work is part of a Fokker Aerostructures project to develop an analytical framework for analysis and design of composite stiffened panels with post-buckling capabilities. This framework will facilitate the preliminary design of composite stiffened structures and allow further optimization without requiring the prohibitive computational cost and complexity of finite element models.","buckling; post-buckling; plates; semi-analytical; composite laminates; combined loading; rotationally-restrained; stiffened panels","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Computational Mechanics","","","",""
"uuid:9e03a589-ea9c-4508-8fbb-a76e6ba2abd7","http://resolver.tudelft.nl/uuid:9e03a589-ea9c-4508-8fbb-a76e6ba2abd7","A potential flow approach to complex 3D flows with actuation surfaces","Gamme, S.R.","De Oliveira, G.L. (mentor); Garcia, N.R. (mentor)","2016","","Windenergy; fast multipole method; FMM; panel code; potential flow","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","","",""
"uuid:a0bcdbba-3ccc-4622-ab8d-6ac2e4a1e598","http://resolver.tudelft.nl/uuid:a0bcdbba-3ccc-4622-ab8d-6ac2e4a1e598","Improved Design of a High Lift System for General Aviation Aircraft","Florjancic, D.","Veldhuis, L.L.M. (mentor); Steenhuizen, D. (mentor)","2015","Relatively high wing loading leads to increase in fuel efficiency in commercial as well as in small general aviation aircraft, but requires sophisticated high lift devices to keep the take-off and landing distances within acceptable limits. High lift devices can in turn have a detrimental effect on cruise performance, and thus fuel efficiency, in the form of additional parasitic drag of the high lift system mechanism fairings under the wing. In addition, the weight and complexity of the high lift system increases with its performance. The purpose of this research is to increase the payload of a highly efficient propeller driven 4-seater general aviation aircraft by improving its plain flap high lift system while the range stays the same. Therefore a detailed design of the high lift system is required, as well as the evaluation of the overall aircraft performance. A study of existing high lift systems in general aviation aircraft is conducted, based on which a preliminary design decision to implement a single-slotted flap with a dropped hinge mechanism is made. An optimization loop is developed within which the flap geometry is generated based on nine design variables (including the position of the hinge point and the flap deflection angle) and the clean configuration airfoil shape. Two-dimensional aerodynamic analysis of the two-element airfoil section is performed by the MSES code at three different angles of attack. A method of reading the maximum value of displacement thickness on the flap upper surface is implemented to algorithmically detect separated flow and discard the flap designs that suffer from separation at low angles of attack in order to avoid jumps in the lift curve. Three-dimensional aerodynamic characteristics of the aircraft with deployed flaps are estimated using semi-empirical methods. The drag of the mechanism fairings is also estimated by a semi-empirical method. A simple performance model is used to predict the payload, which represents the objective function of the optimization. Landing and take-off distances are also calculated using the performance equations. Matlab's genetic algorithm and pattern search algorithm are used to perform global and local optimization of the flap geometry. The resulting single-slotted flap design increase the maximum take-off weight by 13\% which results in the increase in payload of 42\%. Take-off distance increases by 12.5\% and landing distance increases by 16.5\%. Maximum sectional lift coefficient is improved by 27\% with respect to the original plain flap. The additional cruise drag due to mechanism fairings increases the fuel weight by 3\% for the range of 1000 nm. Limiting phenomena in achieving the highest two-dimensional lift coefficient is the bursting of main element's wake, rather than flow separation off the airfoil surface. The method of monitoring the displacement thickness of the flap wake is successful in ensuring that the optimized flap has no jumps in the lift curve.","high lift system; flap; payload; general aviation aircraft","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:df72fe33-57f0-43ec-aab1-0baafd119513","http://resolver.tudelft.nl/uuid:df72fe33-57f0-43ec-aab1-0baafd119513","Transfer strategies to the L3 libration point of the Sun-Earth system","Tantardini, M.T.","Noomen, R. (mentor); Ambrosius, B.A.C. (mentor)","2009","In this contribution, we investigate several trajectory design methods to transfer a spacecraft to the L3 point of the Sun-Earth Circular Restricted 3-Body Problem (CR3BP). Such a study aims at performing an investigation into an area that is so far little explored: the vicinity of L3 has never been the destination of a space mission, and in literature there is a big gap about transfers to the Sun-Earth L3 libration point. We consider several strategies and design methods: various types of two-burn impulsive trajectories in a Sun-spacecraft two-body model, a low-thrust transfer, an approach based on travelling on invariant manifolds of periodic orbits in the Sun-Earth CR3BP, and finally a patched conics strategy exploiting the gravity assist of the nearby planets. We discuss advantages and drawbacks, and we estimate propellant budget and time of flight requirements of each.","trajectory design","en","master thesis","","","","","","","","2009-12-08","Aerospace Engineering","SpE/ AS","","","",""
"uuid:225cfccd-2fc3-4a4d-a8a8-c24bd24bae44","http://resolver.tudelft.nl/uuid:225cfccd-2fc3-4a4d-a8a8-c24bd24bae44","Design of a Semi-Empirical Tool for the Evaluation of Turbine Cooling Requirements in a Preliminary Design Stage","Tiemstra, F.S.","Gangoli Rao, A. (mentor)","2014","There is an everlasting demand for higher cycle efficiencies in gas turbine engines. One way to obtain a higher efficiency is to increase the overall pressure ratio (OPR) of the engine. In order to benefit from the efficiency increase whilst maintaining the same specific gas power, the turbine inlet temperature (TIT) has to increase with it. However, with the extremely high TIT used in modern day gas turbine engines, the melting point of the materials used in nozzle guide vanes (NGV) and high pressure turbine (HPT) blades is already exceeded. Therefore, the vanes and blades rely on active cooling on the in- and outside to prevent it from melting. However, the application of cooling air in the turbine is detrimental to the engine performance and hence is desired to be kept at a minimum. Next to application of a turbine cooling system with high heat transfer coefficients, a lower cooling air massflow can be obtained by using coolant of a lower temperature. The use of cryogenic fuels in hybrid engines currently investigated in for example the AHEAD project, can prove to be useful in that aspect; a heat exchanger can be applied to exchange heat between the coolant and the fuel to reduce the temperature of the cooling air. In this study, a semi-empirical turbine cooling program is developed which is able to calculate the thermal performance of a cooling system configuration and assess the effects of the cooling air on engine performance. For the determination of the heat transfer coefficient and pressure drop in the turbine cooling program, semi-empirical correlations from various journal articles are used rather than relying on computational intensive CFD calculations. Also, the tool is able to predict the cooling air requirement for any turbine cooling configuration to a reasonable level of accuracy, enough to be useful during the engine preliminary design phase. This turbine cooling program is used to study the effects of the cooling air on engine performance and research the feasibility of using pre-cooled coolant in a hybrid engine configuration. This main conclusions of this study are that, as expected, cooling air is detrimental to the engine performance. However, the magnitude of the turbine cooling requirements and hence the detrimental effect on the engine performance is commonly underestimated. Therefore, the proper prediction of turbine cooling requirements is important in early design stages, especially for engines operating at higher OPR and TIT. Furthermore, the cooling air requirements decrease if cooling air of a lower temperature is used. Re-using spent cooling air to cool the next row of vanes/blades turns out to have a negative effect on the engine performance. The findings in this report can prove to be important for future engine design where OPR and TIT values are expected to keep rising. Also, the assessment of the effect of coolant pre-cooling and re-use of coolant come in handy for the intended application in the AHEAD hybrid engine.","gas turbine; turbine; cooling; hybrid engine; coolant; performance","en","master thesis","","","","","","","","2014-06-27","Aerospace Engineering","Flight Performance & Propulsion","","","",""
"uuid:3ba10d0d-c76b-4f32-80df-d0704bd7c963","http://resolver.tudelft.nl/uuid:3ba10d0d-c76b-4f32-80df-d0704bd7c963","Design, Development and Testing of an Attitude Determination Experiment for the European Student Earth Orbiter","Geers, M.A.","Kuiper, J.M. (mentor)","2016","The European Student Earth Orbiter (ESEO) is the main educational project of the European Space Agency that allows students to design, develop and test scientific payloads. The contribution to be made by the TU Delft is a software-based Attitude Determination Experiment (ADE) that contains four different algorithms for attitude estimation that are to be tested in-situ for comparative analysis through the telemetry sent down by the satellite. The four algorithms are the Optimal REQUEST, the Additive Quaternion Kalman Filter, the Pseudolinear Quaternion Kalman Filter and the Multiplicative Extended Kalman Filter. The Additive Quaternion Kalman Filter has been further adjusted with the incorporation of the Maximum Information Rate Filter, which reduces the measurement matrix into six candidates and selects the one corresponding to the highest information rate for use in the algorithm. Though this filter has the benefit of using reduced matrices, computational efficiency is only really increased if the selection process is as computationally lean as possible as well. Therefore, an analysis was performed of the selection pattern of the Maximum Information Rate filter. This analysis shows that a clear pattern exists for the Earth sensor (based solely on the hemisphere), a more complicated pattern is visible for the Sun sensor, while the magnetometer has no useful pattern to speak of. The ADE has been programmed in the C-language and adjusted for the RTEMS real-time operating system. All operations to be performed by the payload have been verified to operate within the assigned budgets and limitations of the hardware on board the satellite. The payload is capable of running the four algorithms within 100 milliseconds while retaining a code size 24 kB, which is lower than the 35 kB budget and a memory size of 8.8 kB, which is lower than the 10 kB budget. All algorithms have undergone extensive Monte-Carlo simulations to test for stability and sensitivity to the involved parameters. All algorithms manage to retain a steady-state angular estimation error lower than 0.5 degrees under conditions varying by about 30% from the expected parameters. At the time of writing, the ADE has passed the Critical Design Review and is ready to be integrated onto the ESEO satellite.","Microsatellite; Attitude; Estimation; Determination; ESEO; Maximum Information Rate","en","master thesis","","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","Space Engineering","",""
"uuid:345ce8d1-d29b-4552-add7-d3f1302fcfae","http://resolver.tudelft.nl/uuid:345ce8d1-d29b-4552-add7-d3f1302fcfae","A Finite Element Approach for Aeroelastic Instability Prediction of Wind Turbines","Castillo Capponi, P.A.","van Bussel, G.J.W. (mentor); Ashuri, T. (mentor); Holierhoek, J. (mentor)","2010","","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","Aerodynamic","",""
"uuid:409082e0-d3f7-47c4-ae76-1811f640bb0a","http://resolver.tudelft.nl/uuid:409082e0-d3f7-47c4-ae76-1811f640bb0a","Critical Parameters in Mode I Interlaminar Fracture Toughness Testing of Thermoplastic Composite Materials","Peters, K.R.","Rans, C.D. (mentor)","2017","The goal of the thesis (executed for Fokker Aerostructures) was to further the understanding of critical parameters in the DCB test method for thermoplastic composites. The influence of fiber bridging, specimen thickness, insert film thickness, crack length and crack opening rate are investigated by means of experimental DCB tests for thermoplastic C/PEKK specimens. Microscopic research is performed in order to link the mechanical behavior to the fractography in the C/PEKK material. The results show that the mode I fracture toughness is influenced by specimen thickness, insert film thickness and crack length as consequence of fiber bridging effects and plastic resin deformation, which can again be related to the tough resin properties and relatively poor fiber/matrix interfacial strength in thermoplastic composites.","DCB test; mode I fracture toughness; GIc; thermoplastic composite; C/PEKK; fiber bridging; insert film thickness; DCB specimen thickness; crosshead opening displacement rate; data reduction method","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","Structural Integrity and Composites","",""
"uuid:5d268e3f-4520-42e9-bab3-fedd794585a6","http://resolver.tudelft.nl/uuid:5d268e3f-4520-42e9-bab3-fedd794585a6","Design of Small Scale Shockwave Generators for the ORCHID Setup","Chew, T.","Head, A. (mentor); Jahn, I. (mentor); Colonna, P. (mentor); De Servi, C. (mentor)","2015","This report focuses on the design and analysis of various subcomponents of the supersonic nozzle test section of the ORCHID setup. The primary concern is a study dedicated to the model support system which is crucial to the success of a series of gas dynamic experiments for high fidelity software validation. Standard design rules and empirical models are not directly suitable for the nozzle test section design, mainly due to the thermodynamic behaviour of the working fluid, which expand close to the critical point. The configuration of such a support system for the model typically consists of a sting and base support. The aim of the study is to design this model configuration and computationally investigate the influence of these non-ideal flow effects on the conceived model and support system. The model support must remain minimally intrusive to the results of the flow field whilst also being structurally sound. Such results will be useful for the ongoing development of realising the ORCHID setup. A number of sub-goals to complete the objective included analysing non-ideal compressible flow simulations, designing the model and support system and conceiving a coupling tool between the fluid and structural domain. A field known as fluid-structure interaction was investigated to model the coupling tool, and it revealed that using a method known as the radial basis interpolation was recommended. This transferred values between the interfacing boundaries of the fluid and structural domain. Several geometric models were investigated and a diamond model was chosen as it transfers the most stress onto the support system. Pertaining to the fluid setup, a frontal height of 9 mm was selected for the diamond based off results and a review of literature concerning the supersonic blockage phenomenon. The Method of Characteristics was also used to generate the diverging nozzle profile. Concerning the structural setup, a low-carbon AISI 1010 steel was chosen. Two test cases were chosen which involved high-fidelity calculations. This required the coupling tool, where information was transferred to the FEA solver. The first case being an aligned case where the model was aligned to the nozzle and the second being a deflected case. Results indicate that the effect of pressure was insignificant for the aligned case, with a maximum stress of 0.564 MPa and deflections at the tip being 6.074 x 10-4 mm. For the deflected case, it was found that the influence of temperature played a major role in the structural integrity; an increase of 500% in stress from the results of pressure influence and 7% in maximum deflection at the tip. The main conclusions drawn are that the support system would not yield under steady state conditions but the deflections observed was considered significant enough such that it may hinder the results of the flow field. As a result, recommendations for future work include conceiving the automation tool to conduct a full two-way fluid-structure interaction process to analyse plant start-up.","FEA; FSI; vapour tunnel; supersonic nozzle; Model Support System","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","Flight Propulsion and Power","",""
"uuid:2355ab39-550c-4447-8c56-61ffabd53353","http://resolver.tudelft.nl/uuid:2355ab39-550c-4447-8c56-61ffabd53353","Mission Planner for Heating-Optimal Re-Entry Trajectories with Extended Range Capability","Papp, Z.","Mooij, E. (mentor)","2014","Atmospheric entry is a process defined by extremes, from the great velocity at the point of entry to the high deceleration loads and aerodynamic heating in the lower layers of the atmosphere. In addition to the vehicle maintaining structural integrity, an equally important aspect of the re-entry mission is safety. This safety can only be guaranteed if the vehicle is controllable throughout the re-entry process. Mission design plays a role in adhering to operational and safety requirements in the form of trajectory planning: the development of a re-entry trajectory wherein the vehicle remains within its operational constraints and is controllable throughout. The focus of this thesis lies on the design-time trajectory development part of mission design, i.e., the development and analysis of feasible trajectories under certain requirements to be flown for a specific mission. The research goal of this thesis is formulated as follows: to what extent can optimal re-entry trajectories be developed in the design-time phase of mission development for a winged entry vehicle that provide a maximum-range capability under the objective of minimizing heat loads and adhering to operational constraints? To answer this question, a mission design tool is developed in four successive stages: 1) Development of the re-entry simulator, 2) Design of the guidance algorithm, 3) Development of the mission planner, and 4) Mission planner testing. The capacity to quickly and reliably simulate re-entry trajectories is paramount to a mission planner. For this purpose, a simulator was developed with the specific goal of later integration with the mission planner. Steering is achieved by modulating the vehicle’s attitude in terms of its angle of attack and bank angle. The guidance profile is based on the specification of attitude commands at specific points in the trajectory related to the instantaneous energy of the vehicle. The course of an entire trajectory can be specified by its guidance profile. The purpose of the mission planner is to develop guidance profiles for trajectories that keep the vehicle within its operational constraints, minimize the heat load, and provide the largest possible range under these conditions. The objectives of minimum heat load and maximum range are conflicting. Trajectories with minimum heat load requirements are generally short in duration with smooth heat flux profiles where the heat flux is maintained close to its constraint value. The total heat load is minimized by keeping the duration of the re-entry as short as possible. This, however, is in direct opposition to the objective of maximizing range, where keeping the vehicle aloft for as long as possible is beneficial. The mission planner develops trajectories by specifying the individual parameters in this guidance profile by performing multiobjective optimization to determine the combinations of parameters that result in optimal trajectories in terms of the mission objectives. The mission planner consistently provides a set of optimal trajectories over a diverse range of objective values and under the provision that operational constraints are met. Optimal trajectories are determined based on these conflicting objectives over a range of objective values, wherein the relative priorities of the objectives are varied. In all cases is the mission planner able to provide trajectories with an extended- range capability, even when minimizing the heat load is considered the main priority.","Re-entry; Guidance; Optimization; Mission planning; Trajectories","en","master thesis","","","","","","","","","Aerospace Engineering","Astrodynamics and Space Missions","","","",""
"uuid:2ae8b406-6026-4ac0-88f4-33fb052c2dae","http://resolver.tudelft.nl/uuid:2ae8b406-6026-4ac0-88f4-33fb052c2dae","Orbital stability assessments of satellites orbiting Small Solar System Bodies","Ruevekamp, S.","Noomen, R. (mentor); Ambrosius, B.A.C. (mentor)","2009","This thesis presentation will discuss stability assessments of orbits around asteroids, with in particular the asteroid Eros. The gravity field of an asteroid can be estimated using different techniques. For the thesis work presented the Polyhedron, Spherical Harmonic Expansion and Triaxial Ellipsoid methods are implemented on the Eros case. The differences in performance of the different gravity field modelling techniques will be discussed. The irregularity of the gravity field of Eros will have consequences on the orbital stability of satellites orbiting Eros, the influence of this irregularity will be estimated. Furthermore, the influence of the Solar Radiation Pressure and Third-body Perturbing forces on the stability of orbits around Eros will be determined. With the help of the Monte Carlo method and the Particle Swarm Optimization method a search is performed to find stable orbits within the vicinity of Eros.","stability of orbits","en","master thesis","","","","","","","","2009-12-08","Aerospace Engineering","Space Engineering - Astrodynamics and Space Missions","","","",""
"uuid:b980aab7-f346-4030-97a3-a3cde13a51d6","http://resolver.tudelft.nl/uuid:b980aab7-f346-4030-97a3-a3cde13a51d6","Optimization, Scaling and Economics of Pumping Kite Power Systems: Small-scale Systems for Developing Countries or Utility-scale Units for the European Market?","Grete, C.","van Bussel, G.J.W. (mentor); Schmehl, R. (mentor)","2014","","Optimization; Scaling; Economics; Developing Countries; Kite Power System; Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion / Wind Energy","","Sustainable Energy Technology","KitePower",""
"uuid:7e5b83c7-fb42-46f4-a85f-a0dab2a3f178","http://resolver.tudelft.nl/uuid:7e5b83c7-fb42-46f4-a85f-a0dab2a3f178","Simulating flutter for a 100-m wind turbine blade: using a CFD-CSD coupled method in OpenFOAM","","Van Zuijlen, A.H. (mentor)","2016","In this study a full CFD-CSD FSI method is developed, extended with a modal approach, to assess the potential flutter behavior of the SNL 100-m wind turbine blade. The FSI method is based on the existing FOAM-FSI framework and extended with a non-linear beam model. The analysis consists of four steps: non-linear steady state FSI deformation of the blade; extracting force distribution gradients of blade deformations along eigenmode shapes; linearize the flow around the steady state using a modal approach; ans simulate the fully linearized model to assess the stability of the system. The method is applied to the SNL 100-m blade in a parked configuration, with nonturbulent, non-yawed inflow wind speeds of 50m=s and 70m=s. The results show a stabilizing effect of the flow for both cases. A further analysis of the modal model suggests that the coupling between the flapwise bending modes and torsional modes are indeed strong, but do not cause an instability for the test case considered. The results of the modal analysis are lightly verified with full CFD results.","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","","",""
"uuid:f2184fad-7f9b-49ed-8457-fca896ce2ec8","http://resolver.tudelft.nl/uuid:f2184fad-7f9b-49ed-8457-fca896ce2ec8","Turbulence modelling of cavitating flows in cryogenic turbopumps","Mani, K.V.","Hickey, J.P. (mentor); Cervone, A. (mentor)","2015","Robust turbulence modelling of cavitating flows is essential for physically accurate predictions of the performance characteristics of cryogenic rocket turbo-pump inducers. Numerical modelling of such flows complement experiments and are comparatively inexpensive, but they lack accurate predictive capabilities. This work focuses on the characterisation of the choice of turbulence models on cavitation predictions for the modelling of cryogenic turbo-pump inducer. To isolate the influence of the turbulence modelling effects on the concurrent physical phenomena arising in the inducer, four canonical problems are abstracted and studied individually to separately consider rotation, adverse pressure gradients, blade passage and bluff body cavitation. Additionally, cavitation bubble dynamics in a bubbly flow in a 3D inducer are numerically simulated and studied so as to understand the effects of such on flow turbulence. It has been found that the type of cavitation model and the choice of turbulence model play a major role in the prediction of phase-distribution in the flow and concomitantly, on the cavitation induced instabilities predicted from computational fluid dynamics. The influence of the turbulence model is strongly dependent on the type of flow and a universal model which can be used to accurately predict cavitation in all flow domains seems to be unavailable among the existing classical turbulence closure models (both for two-equation and second-order closures). Stark differences in the predictions of cavitation are observed among non-bounded, bounded, and rotating flows based uniquely on the selection of turbulence models. The influence of other parameters such as the thermo-physical fluid characteristics, Reynolds number, or turbulence intensity have a minor effect for non-bounded flows. On the other hand, cavitation arising within the blade passage (bounded flows), the selection of the thermo-physical characteristics has a great effect on the cavitation prediction. Simulations of bubble dynamics using the Rayleigh-Plesset equation in cryogenic bubbly flows, with and without thermal effects, clearly depict the cavitating regions in a 3D inducer and yield corresponding bubble oscillation frequencies and time scales. The thermal effects attenuate bubble oscillations and distinct dominant frequencies of oscillations are observed for changing initial bubble radii. The information obtained from the turbulence model influence on cavitation and bubble oscillation influence on flow turbulence is used in the analysis of turbulence-cavitation interaction. A set of considerations are provided to turbo-pump designers as they need to carefully consider the choice of turbulence model and cavitation physics in order to use CFD tools to predictively model cryogenic inducers. These considerations will in turn help to improve dependability of the CFD tools, which will lead to reduced computational and monetary costs.","Turbopump; Cavitation; Turbulence Modelling","en","master thesis","","","","","","","","","Aerospace Engineering","Earth Observation and Space Systems","","Space Systems Engineering","",""
"uuid:87bc9f46-5f40-4a87-9716-65f7e3ac7c29","http://resolver.tudelft.nl/uuid:87bc9f46-5f40-4a87-9716-65f7e3ac7c29","Design, manufacturing and characterisation of a water fed CubeSat micro-resistojet (Dondersteen)","Poyck, R.M.A.","Cervone, A.C. (mentor)","2014","To further the applicability of nano-satellites in large scale relevant missions, it is necessary that they have their own propulsion system for manoeuvring. Multiple nanosatellites flying in formation or even a constellation, with a distributed network of instruments can obtain simultaneous, distributed and guided measurements, which are not possible with conventional single-spacecraft architectures. A cubesat propulsion system technology demonstration has been shown on the Delffi-N3Xt satellite. Demonstrating cold gas generators, which generate self-pressurising nitrogen propellant from solid material. Now comes the time for an operational demonstration of powerful, innovative and effective propulsion for adequate manoeuvrability potential. This operational demonstration will be undertaken by the DelFFi mission, by having two nano-satellites demonstrating formation flying capabilities, such as inter-satellite distance maintenance. The DelFFi satellites will operate in a network of 50 nano-satellites, called the QB50 mission, with the goal to take multi-point in-situ measurements of the lower thermosphere and research re-entry. The gas generator based cold gas system have however been shown to be unable to produce the necessary total impulse within the stringent mass and volume constraints. The formation flying objective requires a new high performance propulsion system, which is designed during this master thesis. In order to design this propulsion system a number of tests were conducted on the candidate components and assemblies. After a survey of all commonly mentioned reaction engines, a resistojet was found to best meet the needs of this mission. Mainly because resistojets are relatively uncomplicated, do not require combustion and have a relatively low power consumption per amount of impulse generated. The best propellant for resistojets, selected from a large number of possibilities, was found to be water. Water was chosen because it is liquid around room temperature, It has a high potential impulse bit per unit of mass, it is benign, cheap and readily available. Based on the requirements on the propulsion system the following necessary design parameters were found: a water propellant mass of 50 [g], a nitrogen pressurant mass of 0.2 [g], a storage pressure of 4.5 [bar] to 2.5 [bar], a nozzle throat diameter of 25 [?m], a nozzle area ratio of 20 [-] and a final propellant heating temperature of 500 [°C]. The resulting propulsion system performance is: a total velocity increase ?V of 21.01 [m/s] (with a satellite mass of 3 [kg]), a total thrusting time of 17 [h] and 56 [min], a power consumption of 6.8 [W] to 3.7 [W] and a thrust force of 1.4 [mN] to 0.8 [mN]. A resistojet propulsion system requires pressure to transport the propellant from the storage tank to and through the thruster. Because pre-pressurisation is generally not allowed in CubeSats, gas generators were found to be the best option. These gas generators can be electrically initialised in orbit, where they produce gas from a solid. Gas generators used for airbag initiation in the automotive industry were found to be unsuitable for this mission because of the high shock pressure of possibly up to 95 [bar]. Additionally, three out of four gas generators that were tested malfunctioned. The reason for this malfunctioning is still unknown. For the DelFFi mission a waiver was granted, allowing pressurisation before launch. Therefore pre-pressurisation is considered to be the best option for propellant pressurisation. The most innovative part of this thesis is the development of the MEMS micro-thrusters called Dondersteen. These consist of an integrated fluidic inlet channel, heating chamber and rocket nozzle, which are all etched in silicon. The propellant is heated using heating elements made out of the very strong material silicon carbide. These elements are suspended in the middle of the fluid flow in order to maximise the heat transfer to the propellant, and minimise the heat loss to the surroundings. The novelty not only lies in the geometry, but also in the manufacturing process. Hereby the fluidic channels and suspended heating element are both etched out of the silicon carbide covered silicon wafer in the same two etching steps. The developed thruster consists of the following three distinct sections: inlet, heating chamber and nozzle. Multiple designs were made for each of these sections. The production process was chosen such that any combination of these sections can be etched behind one another. This creates the flexibility of being able to produce and test multiple thruster layouts, in order to find the one which best fits the requirements. Different heating chamber geometries were designed and tested. These enable the assessment of the geometrical influence on heat loss, pressure drop and propellant heating capabilities. Both the manufacturing process and the resulting heating chambers show great potential. The heating elements have been shown to be robust during the rough testing process. The propellant channels have very favourable rounded edges which reduce pressure and heat losses, while maximising the heating contact and propellant mixing. Due to the experimental nature of the manufacturing process the fluidic channel dept was found to be too large and the nozzle throat diameters were too large. The performed analysis of these discrepancies will be used to improve the manufacturing process. The tested resistance values of the resistive heater modules were found to be 200 to 600 times larger than designed. This increases the required input voltage from 5 [V] to the range from 70 [V] to 120 [V]. For the current testing phase this is not a problem since these supplies are available. The flight models will however have to be redesigned in order to comply with the 5 [V] requirement of the satellite power supply. The main reason of this discrepancy was found to be a calculation error. Some adjustments have already been listed with which this resistance can be decreased by a factor of 144. Further design efforts will have to increase this factor to obtain the real design value of the resistance. There are some tasks that still have to be performed by a succeeding master student to consolidate the work done in this master thesis to a propulsion system flight model. The developed thrusters have to be performance tested with propellant in multiple operating conditions. The results of these tests lead the final redesign of the developed thrusters. The propellant storage system needs to be built and tested. Finally the complete in flight propulsion systems has to be defined, built and integrated into the satellites.","","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","Space Systems Engineering","",""
"uuid:85bbf142-df34-446a-af4e-b18721f7f8ed","http://resolver.tudelft.nl/uuid:85bbf142-df34-446a-af4e-b18721f7f8ed","Incorporation of Recoverable Robustness and a Commercial Revenue Metric into Tactical Stand Allocation","Dijk, B.","Santos, B.F. (mentor); Pita, J.P. (mentor); Curran, R. (mentor)","2016","This thesis deals with an important resource planning problem at airports: the stand allocation problem. More specifically, it is aimed to obtain a robust tactical stand allocation for the airport, at limited cost. We incorporate the concept of recoverable robustness in a stand allocation model and formulate a recoverable robust stand allocation model. Furthermore, we test a new objective functions for the stand allocation model: maximization of affinity based on air-side commercial revenues, and compare it with three common objectives for the stand allocation problem. The recoverable robust stand allocation model is tested in a case study with Guarulhos International Airport of São Paulo. The recoverable robust solutions are demonstrated to outperform the solutions of a non-recoverable approach. Furthermore, the comparison between the four objectives indicated the practicality of the affinity objective and the trade-off an airport can make for tactical stand allocation.","Airport Stand Allocation; Recoverable Robustness; Commercial Revenue","en","master thesis","","","","","","","","2019-03-04","Aerospace Engineering","Control & Operations","","Air Transport and Aerospace Operations","",""
"uuid:918b7f98-330e-4de9-8ffa-34bc2cd6f805","http://resolver.tudelft.nl/uuid:918b7f98-330e-4de9-8ffa-34bc2cd6f805","Airline Schedule Planning Considering Interactions with Airports Constraints","Muhawe, V.","Zhao, W. (mentor); Curran, R. (mentor)","2016","","","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Air Transport & Operations (ATO)","",""
"uuid:9f238a03-4e0e-4e43-9159-a2c8b2689747","http://resolver.tudelft.nl/uuid:9f238a03-4e0e-4e43-9159-a2c8b2689747","Analysis of driving parameters for green flight trajectories","Grande Pardo, J.","Grewe, V. (mentor)","2016","Climate change is an important problem nowadays. There are several industries causing this problem. One of them is the air transport industry. In order to reduce its induced climate impact there are different approaches: design of new aircrafts or engines, use of alternative fuels, more efficient air traffic management, or re-routing. All of them except re-routing aim on reducing carbon dioxide emissions. Re-routing, on the other hand, aims on reducing the climate impact of non-CO2 emissions (that considerably alter their climate impact depending on the region of the atmosphere where they are released) by increasing slightly the carbon dioxide emissions. This study focuses on this last approach. It establishes an analysis of the results obtained within the REACT4C project (Reducing Emissions from Aviation by Changing Trajectories for the benefit of Climate). The project aims to reduce aircraft induced climate impact in the North Atlantic flight corridor by changes in flight trajectories and considers fleets of around 400 aircraft. Moreover, this project considers eight different weather patterns (three for summer and five for winter), two flight directions (westbound and eastbound), and three climate metrics. Therefore, a total of 48 configurations have to be studied. Moreover it considers six different climate parameters causing the total climate impact. The climate parameters are carbon dioxide, water vapor, contrails, and NOx. The NOx climate impact is obtained as the summation of ozone, methane, and primary mode ozone climate impacts. The results that are analyzed are the climate impact caused by each of the climate parameters and how this climate impact changes when applying gradual changes on the aircraft trajectories. The analysis shows that water vapor has a negligible effect on climate impact. Carbon dioxide climate impact is more relevant when considering long term time horizons. Also, it increases when more trajectories are modified since the fuel consumption increases. Contrails are the main driver of the optimization for seven out of eight weather patterns. Their climate impact goes down during the optimization. Moreover, they are more important when considering short term time horizons and westbound flights. NOx is driving the optimization for only one weather pattern. Its contribution to reduce the total climate impact during the optimization is higher in the long term due to the enhanced net-cooling effect caused by methane depletion. Moreover, it is more important for eastbound flights. However, for winter weather patterns, NOx is controlled mainly by methane and primary mode ozone during most part of the optimization. Ozone is only important in the first and last segments. In addition, ozone presents the highest values of climate impact and has more contribution in the short term; while methane has always a negative climate impact or net-cooling effect due to its depletion, and is more important in the long term. The climate impact reduction is caused in the first part of the optimization by a small number of flights that reduce considerably their climate impact. Their trajectories change to go through regions of the atmosphere where their climate impact is smaller. As the optimization progresses, there are more flights modifying their routes. However, their climate impact reduction is not as noticeable as in the first cases. This happens because the regions of the atmosphere where the emissions have a lower climate impact are busier with the prior flights. Therefore the latter flights changing their trajectories have less potential to reduce their climate impact. This leads to a small part of the fleet causing an important climate impact reduction while the vast majority of flights slightly reduce their climate impact.","Climate impact; eco-friendly re-routing; REACT4C project; North Atlantic flight corridor; Climate Cost Functions; aircraft routing; aircraft emissions","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Operations","","Aircraft Noise and Climate Effects (ANCE)","",""
"uuid:fecce3dd-c613-4a11-860f-7648d8fd42b9","http://resolver.tudelft.nl/uuid:fecce3dd-c613-4a11-860f-7648d8fd42b9","Design of a MEMS micro-resistojet","Mathew, T.V.","Zandbergen, B.T.C. (mentor); Gill, E.K.A. (mentor); Mihailovic, M. (mentor); Creemer, J.F. (mentor); Sarro, P.M. (mentor)","2011","","","en","master thesis","","","","","","","","","Aerospace Engineering","Space Systems Engineering","","","",""
"uuid:1465fa5a-9d68-4d20-97db-1133405b9579","http://resolver.tudelft.nl/uuid:1465fa5a-9d68-4d20-97db-1133405b9579","Optimal Control of Reaction Wheels Disturbance Transients","Cocci, E.","Guo, J. (mentor)","2016","Randomly occurring torque transients have been detected in the reaction wheels of several spacecraft. The causes of the transients are presumably cage instabilities and oil jogs occurring in the ball bearings of the wheels. Within high precision pointing missions these disturbances significantly impair pointing-stability performance. Hence, the goal of this thesis is to investigate how the impact of wheels’ disturbance transients on the pointing performance parameters can be minimized through the implementation of dedicated control strategies. Eventually, the capabilities of the Precision Pointing Control Design tool developed by Airbus Defence and Space can be further extended and improved with respect to friction torque instabilities. The torque profiles generated by friction instabilities have been characterized by the means of a pseudo-power spectral density formalism allowing to analytically perform accurate pointing error analysis and evaluations, following the ECSS standard. Moreover, two different solutions have been investigated and implemented on a reference case study mission. While the first one consists in the optimization of the controller’s integral bandwidth with respect to the disturbance transients, the second solution considers the design of a wheel speed control loop. The implementation of an inner control loop nested in the global attitude control loop turns out to be the most promising strategy for handling disturbance transients. However, the research shows that angular rate sensors are a crucial element for the pointing performance and stability of the whole control loop. Therefore, at the end of the thesis, guidelines to further optimize the in-house control design tool and to characterize the pointing error sources analytically are presented. Additionally, in order to pave the way for a practical implementation of the wheel speed loop strategy, the specific requirements regarding the rate sensor that should be provided to the wheels’ manufacturer are discussed.","","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:e8527460-df6c-4a08-838d-247566fa4c44","http://resolver.tudelft.nl/uuid:e8527460-df6c-4a08-838d-247566fa4c44","The controllability of a winged hypersonic vehicle under aeroelastic effects","Van Dooren, R.M.","Mooij, E. (mentor)","2016","","Aeroelasticity; Controllability; hypersonic","en","master thesis","","","","","","","","2018-01-01","Aerospace Engineering","Space Engineering","","Space Flight","",""
"uuid:1e1941d0-2171-4bc4-95b8-7e01b9c8425d","http://resolver.tudelft.nl/uuid:1e1941d0-2171-4bc4-95b8-7e01b9c8425d","Synthesis of Novel Aircraft Concepts for Future Air Travel","Elmendorp, R.J.M.","Vos, R. (mentor)","2014","In the last 60 years many new technologies have entered the aerospace industry, but the overall aircraft design remained virtually unchanged. If we compare an aircraft built in the 1960's with the latest generation, they look strikingly similar. Only small evolutionary changes entered the commercial aircraft market. A lot of these changes are driven by the ever-lasting quest to reduce the amount of burned fuel. However, the reduction in fuel usage which can be gained with these small evolutionary changes decreases every aircraft generation. A revolutionary change in the aircraft design is needed to make step-change in aircraft fuel efficiency. Changing the configuration of the aircraft could create opportunities for aerodynamic and structural improvements, which will result in higher fuel efficiency. Current tools used in the field of aircraft design use a lot of empirical data obtained from the analysis of existing aircraft. These tools are not capable of correctly analysing unconventional aircraft configurations. A design tool, called the Initiator, is created which is able to synthesise a conceptual aircraft design based on a given set of top level requirements for a wide range of aircraft configurations including conventional aircraft, canard aircraft, Prandtl-planes and Blended-Wing-Body aircraft. The Initiator is verified by comparing the output of the Initiator with existing aircraft. A selection of thirteen reference aircraft varying from small regional jets to wide-body long-range jet-powered aircraft is made to verify the tool. Top level requirements are defined which match the payload, harmonic range and runway performance specifications of the reference aircraft. The aircraft generated from these top level requirements are compared to the existing aircraft. The design process is proven to work, since it converges to a feasible aircraft design which complies with the top level requirements. By comparing the maximum take-off weights and operational empty weights, it can be shown that the generated aircraft are similar to the reference aircraft. Nine out of the thirteen generated aircraft are estimated to within 10% of the reference aircraft weights. Visual inspection and comparison of external aircraft dimensions show that the implemented design rules are capable of generating an aircraft which is similar to the reference aircraft. The design tool was used to compare the different aircraft configurations. The design process works for conventional, canard, three-surface and Prandtl aircraft. Testing the design process for the Blended-Wing-Body was unfortunately not possible with the current state of the sizing methods. The canard aircraft design results in a 12% reduction in fuel mass and a 28% reduction in operational empty mass in comparison with a conventional aircraft designed for the same payload and harmonic range. However, since none of the analysis methods have been validated the confidence in the results gained from the configuration comparison in low. It can be concluded that the design tool can be used to synthesise and compare a wide range of different aircraft configurations.","aircraft design; conceptual design; mdo; kbe; initiator; design and engineering engine; novel aircraft","en","master thesis","","","","","","","","2014-01-29","Aerospace Engineering","Aerospace Design, Integration & Operations","","Aerospace Structures and Design Methodologies","",""
"uuid:291207fc-5ada-435c-be39-8e1436fd96c9","http://resolver.tudelft.nl/uuid:291207fc-5ada-435c-be39-8e1436fd96c9","Fixed-Wing UAV Integrated Navigation with Low-Cost IMU/GPS","Hummelink, B.A.","Chu, Q.P. (mentor); Mulder, J.A. (mentor); De Croon, G.C.H.E. (mentor); De Wagter, C. (mentor)","2011","Today, there is an increase in the use of Unmanned Aerial Vehicles (UAV's), for applications that can be considered dull, dirty or dangerous when compared to those applications of conventional aircraft or helicopters. To further increase the use of UAV's, their navigation filters must be robust and reliable. The trend in current autopilot development is defined by the ever decreasing size of vehicles leading to the creation of miniature Inertial Navigation Systems (INS) with low cost, low grade sensors. Small flying vehicles have fast dynamics requiring higher control rates and higher dynamic ranges with minimal available onboard computational capacities. Sensor and processing limitations have consequences for the achievable navigation performance. This in turn poses limits on the minimal vehicle stability, weather conditions and trajectory smoothness. The most important aspect and thesis goal is to guarantee the navigation filter solution robustness during all flight maneuvers. A navigation filter is an integration algorithm that provides a navigation solution on the vehicle's state vector from sensor data. This thesis focuses on one UAV platform in particular, namely small fixed-wing UAV's. One of the main challenges with designed navigation filters is that they can be theoretically stable but the outcome can sometimes not be used. In practice, the navigation filter outcome can give a diverging solution while theoretically stable. The goal of this thesis is to define the minimal requirements of sensors and other hardware for an INS such that the stabilization requirements posed by the vehicle dynamics and size can be satisfied. With the requirements stated, smaller and more dynamic fixed-wing UAV's can be stabilized based on the integrated navigation solution. The developed observability analysis tool is able to provide a quantitative analysis on the state observability that can be used to analyze different systems or sensor configurations. The observability matrix is composed of the system and observer dynamics. The system dynamics is based on the Inertial Measuring Unit (IMU) prediction of the system states, the observer equations correspond to the observer dynamics. A non-linear local observability analysis has been performed to calculate the observability matrix. The traditional Singular-Values Decomposition (SVD) algorithm provides the singular values of an observability matrix in a decreasing order and indicates the rank of the system. The rank of the observability matrix corresponds to the number of observable system states, the SVD can however not directly link the singular values to the system states. To overcome this problem a different matrix decomposition is used that is able to directly couple the singular values to the system states. This developed matrix decomposition algorithm is based on the QR factorization, called QRsvd. With this algorithm it is possible to quantitatively indicate the observability (degree) of each system state. An analysis into the physical properties of fixed-wing aircraft kinematics resulted in new insight into the movement of flying vehicles. Based on the derived kinematics together with the coupling of an IMU, GPS receiver and fixed-wing aircraft kinematics this resulted in new physical insight. This resulted in three angle correction (AC) equations that can be used as additional attitude/heading angle observers to the conventional IMU/GPS integration. With these three additional observers, the three orientation angles become instantaneously observable. Without the AC equations, a rotational rate constraint is always present to integrate the IMU with GPS. GPS receivers and IMU are separate, self-contained subsystems with different updating frequencies and processing times. Resulting clock differences are called time synchronization errors and result in filter estimation problems. A time synchronization requirement is derived, which is a function of changes in vehicle accelerations and filter innovation. The time synchronization requirement is proportional to the magnitude of the change in vehicle accelerations a and negatively proportional to the magnitude of the identification filter innovation. Vehicles with fast dynamics, like fixed-wing UAV's, can have larger changes in vehicle accelerations magnitude, resulting in a more stringent time synchronization requirement. Based on performed simulations and verification with flight test data, it can be concluded that the improved IMU/GPS filter with AC equations can provide a stable long-term navigation solution with accurate short-term performance, by using (Iterated) Extended Kalman filters. During the performed simulations the position states give the largest source of error, due to the large GPS position uncertainty. For the three orientation angles, the heading angle has a larger identification error compared to the pitch and roll angle. For the orientation angles, the influence of atmospheric wind on the identification performance is minimal except for the heading angle due to the presence of a side-slip angle beta. Coordinate transformations between the Earth, North-East-Down (NED) reference frame F_E and the body-fixed reference frame F_B can be performed using a rotational transformation matrix R_BE. The antisymmetric matrix R_BE holds special properties that can be utilized and fits in the category of Special Orthogonal Lie groups with a dimension of three, called SO(3). Based on SO(3) group properties, a non-linear complementary filter can be constructed that uses this matrix as a single state. The non-linear complementary filter on the SO(3) group, can be used as an alternative to conventional Kalman state identification filters. For (I)EKF the heading angle is the largest source of error of the attitude/heading angles, this is also the case for the SO(3) filter. Differences between the SO(3) filter and (I)EKF are due to two aspects. The SO(3) filter uses constant proportional and integrator gains, where Kalman gain matrices include process and observer uncertainties. The other source of differences can be found in the strong coupling between the individual attitude/heading angles for the non-linear SO(3) filter compared to (I)EKF.","UAV; IMU; GPS; Kalman; filtering; identification; observability; Lie groups","en","master thesis","","","","","","","","2016-06-01","Aerospace Engineering","Control and Simulation","","","",""
"uuid:6dd80e53-ebaa-40ec-832b-71b46eca3684","http://resolver.tudelft.nl/uuid:6dd80e53-ebaa-40ec-832b-71b46eca3684","Aircraft Passenger Comfort Enhancement by Utilization of a Wide-Body Lower Deck Compartment","Moerland, R.G.","Vos, R. (mentor); Vink, P. (mentor)","2015","Growing passenger dimensions and the demand for more comfort in the economy class cabin is a trend that is becoming more important during aircraft conceptual design. Based on recent investigations, it is known that current aircraft seat dimensions are not suitable and safe for a large part of the world population. Therefore, a change in aircraft conceptual design thinking, by taking human anthropometry into account, is required. This thesis investigates the opportunity to change the aircraft during conceptual design as well as the opportunity to change current aircraft in order to provide a higher level of passenger comfort and safety. To measure the latter, a comfort model is created, based on scientific research and human dimensions, allowing for the measurement of comfort related to seating configurations, seat characteristics, and cabin dimensions. By establishing the ideal seat dimensions, it is shown that conceptual aircraft designs for the worldwide 95 percentile passenger require wider, but shorter, fuselages. Using the Initiator as a conceptual design tool, four short-haul and four long-haul aircraft are modeled for a range of seat dimensions. Based on an inside-out aircraft design approach, it is shown that similar aircraft performance characteristics are obtained when designing for the worldwide 95 passenger percentile. Moreover, a similar level of direct operating costs, and hence profitability, is attained. However, designing for the worldwide 99 passenger percentile yields considerably higher fuel burn rates and operating costs. An average increase of 3.9 % among all modeled aircraft is seen for the harmonic fuel burn, leading to an increase of 4.2 % in direct operating costs. Considering existing aircraft, use is made of an outside-in aircraft design approach to assess a set of performance characteristics. Based on an average utilization of 37 % of the cargo space in commercial transport aircraft, a potential is shown for a different utilization of the aircraft lower deck, allowing the airline to provide more passenger comfort while retaining a similar level of profitability. Using the Airbus A340-300 as reference aircraft, it is shown that the placement of passengers in the lower hold is feasible from a regulatory, ergonomical, economical, and structural point of view. Based on a reference three-class layout with 267 passengers, it is shown that a lower deck seating compartment provides an increase of 14.6 % in the number of passengers when similar seat properties are used as on the main passenger deck. The installment of additional furnishing and required structural reinforcements results in a decrease of 12 % in maximum structural payload weight. Nevertheless, it is shown that the placement of passengers in the lower deck yields higher profitability rates for the airline when compared to the carriage of additional freight. Secondly, the placement of lavatories and galleys in the aircraft lower deck is investigated, allowing for a maximum increase of 13 % in passenger seats. To allow for the installment of galley lift systems, staircases, and required safety measures, a decrease of 6.27 % in maximum structural payload is attained. By subsequently increasing seat characteristics on the main deck, an increase of 12 % in passenger comfort is achieved for the worldwide 95 passenger percentile. The airline profitability level associated to this comfort layout in turn relates to an average carriage of 5300 kg of freight during the aircraft service life, being equal to the current average. For both the lower deck seating and service utilization, it is concluded that the flying experience of the passenger is increased, while a similar level of airline and manufacturer profitability is obtained. Aircraft lower deck utilization can therefore be seen as a feasible replacement for conventional aircraft configurations.","lower deck; passenger comfort; comfort model; aircraft; wide-body","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:676ab40a-6636-485f-935c-f3cb6fd743a4","http://resolver.tudelft.nl/uuid:676ab40a-6636-485f-935c-f3cb6fd743a4","Innovative material solutions for economical composite bridges with large spans and constrained slenderness","Wilken, A.P.","Bergsma, O. (mentor); Veltkamp, M. (mentor)","2016","FiberCore Europe is a Dutch company, specialized in the design and manufacturing of composite, load-bearing structures for architecture and infrastructure. The company’s main focus is on bridges and lock gates made from glass fiber reinforced polymer (GFRP). The price for currently produced GFRP bridges longer than approximately 26 meter is often higher than the price for bridges made from conventional steel or reinforced concrete. FiberCore Europe is looking for ways to lower the material costs for longer composite bridges to expand their market. This research focusses on two solutions to lower the material costs. These solutions are based on the implementation of stiffer material in the current GFRP bridge concept. Doing so yields a hybrid composite structure. The two materials addressed in this study are structural steel and standard modulus carbon fibers. Combining glass fibers, polyester and fully embedded steel or carbon fibers in large, load-bearing civil engineering structures is a new topic. This requires research on material behavior and design modelling. Tests are performed to assess the corrosion characteristics of steel embedded in GFRP and the strength of the adhesive bond between GFRP and steel. A comparison of 14 different carbon fiber fabrics was made to determine the most suitable carbon fabric in combination with a polyester matrix. Hybrid carbon-glass-polyester laminates were built and tested. A design model has been created to compare different hybrid design sub-concepts with each other and with the reference GFRP bridge. The model is implemented in a Microsoft Excel design tool. The tool shows that it is possible to lower the material costs, the mass and the design height of a GFRP bridge simultaneously by embedding steel. Carbon fibers can lower the mass and the design height of the bridge even more, but only at increased material costs. Initial concerns with respect to the interfacial bond strength between carbon fibers and polyester were confirmed. Taking the total costs of ownership into account, hybrid composite bridges are cheaper than bridges from conventional materials. This is mainly due to the savings on maintenance costs over a design lifetime of 100 years.","composite bridge; hybrid material; carbon fiber; glass fiber; steel; polyester","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","Design and Production of Composite Structures","",""
"uuid:8e4e436a-de0a-40c8-b41b-e2d6e0bacb67","http://resolver.tudelft.nl/uuid:8e4e436a-de0a-40c8-b41b-e2d6e0bacb67","Moblie Rail Survey System: Een nauwkeurig en betrouwbaar systeem voor spoormetingen?","Hellemons, J.F.L.","Tiberius, C.C.J.M. (mentor); Hanssen, R.F. (mentor)","2009","","GPS; INS; Laserscanner; Kalman filter","nl","master thesis","","","","","","","","2009-08-28","Aerospace Engineering","Geomatics Engineering","","","",""
"uuid:c74550a7-10a4-4fad-997d-ec7e1fb82398","http://resolver.tudelft.nl/uuid:c74550a7-10a4-4fad-997d-ec7e1fb82398","Development of an in-panel attachment method for fiber-placed composite lattice and grid-stiffened structures","Smeets, B.J.R.","Kassapoglou, C. (mentor)","2016","Composite grid-stiffened and lattice structures have been the focus of an increasing amount of research over the past decades, mainly because of their excellent structural performance. Most of the previous and current research focuses on analysis, manufacturing, and optimization of the base structure. Although more and more is becoming known about grid structures, methods for introducing loads mid-panel are scarce. With some applications requiring hundreds of attachment points, the potential impact of the attachment points is significant. Therefore, development of an efficient attachment method can allow grid structures to be used in an increasing number of applications. Recognizing the state of the art, a new concept for in-panel attachments is developed, which adds a laminate patch between the ribs of the structure to allow traditional fastening methods to be used. To analyze this concept, a rapid analysis method is constructed which makes use of several analytical methods and a fully parametrized finite element model to predict the strength of the attachment point. The feasibility of the concept and the used analysis method are validated by destructive testing of multiple test samples, and correlating the obtained data to the model. Resulting from the observations, several improvements are made to the model. Although some issues in the base structure are identified in the process, the feasibility of the novel attachment method is shown.","Fiber-reinforced polymer; composite; lattice; grid-stiffened; attachment","en","master thesis","","","","","","","","2021-07-08","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:0ab333f5-8f48-4bad-8819-c0bf7b980262","http://resolver.tudelft.nl/uuid:0ab333f5-8f48-4bad-8819-c0bf7b980262","Innovation of the runway system maintenance strategy at Amsterdam Airport Schiphol using the Value Operations Methodology","Bennebroek, B.J.J.","Van der Zwan, F. (mentor); Curran, R. (mentor); Stoop, J. (mentor); Kamminga, F. (mentor); Emsbroek, G. (mentor)","2012","The main goal of this research is to create and analyse a series of alternative runway system maintenance strategies for Amsterdam Airport Schiphol. For the analysis, a trade-off framework is built to determine whether these alternatives are an improvement over the current strategy. This framework thus assists the decision making process regarding the runway system maintenance strategy. In the trade-off not only the goals of the airport operator are considered, but the interests of all relevant stakeholders are taken into account. The trade-off framework is founded on the concept of 'value' and the philosophy of 'value-focused thinking'. To make this concept and the framework operational, the Value Operations Methodology (VOM) is chosen as the central methodology in this research. While the general approach of the VOM is well defined in literature, several steps in the methodology lacked a sound theoretical foundation. By thoroughly analysing each step, a number of improvements to the VOM are proposed in this research.","VOM; Value Operations Methodology; value engineering; value-driven design; value; value-focused thinking; decision making; airport; runway; runway maintenance; maintenance strategy; Schiphol; Airside Value Model","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Design, Integration & Operations","","Air Transport and Operations","",""
"uuid:ce39c628-e060-401d-a7e6-dd527c296d4e","http://resolver.tudelft.nl/uuid:ce39c628-e060-401d-a7e6-dd527c296d4e","Drawing behavior of UHMWPE films made from solution casting: Influence of solvent quality","Enganati, S.K.","Bergsma, O.K. (mentor)","2016","Ultra-High Molecular Weight Polyethylene (UHMwPE) fibers are well known for their very high specific mechanical properties such as tensile strength and Young’s modulus. The solution spinning/solid state drawing process invented in the late 70s at DSM enables the production of these UHMwPE fibers with outstanding mechanical properties. The achievable maximum draw ratio of the UHMwPE fibers dictates their mechanical properties. One of the possible ways to improve this maximum draw ratio (λmax) is by decreasing the quality of the solvent used for its production. Modifying the solvent in the production of UHMwPE fibers might be a way to achieve higher properties. The focus of this project is mainly to study the influence of different solvents on the production of high strength UHMwPE films/fibers. Various ways were used to decrease the quality of the solvent to gel cast UHMwPE films and then the effect of this solvent quality on the drawing properties was determined. Subsequently, the molecular between the entanglements (Me) of polyethylene chains in different solvents was investigated using shear rheology. Morphological analysis (SEM, XRD) was performed to understand the topology, crystallinity, crystal thickness of the films made in different solvents. It was found that solvent quality has a significant effect on the maximum attainable draw ratio. SEM analysis was able to distinguish between drawable and undrawable UHMwPE films. However, from XRD analysis it was found that the crystal thickness is not the controlling factor for the improvement in drawability. The required difference Me of polyethylene chains in different solvents was found but it was within the experimental accuracy which made it difficult to conclude. Furthermore, preliminary study of some of the selected solvents on the production of UHMwPE fibers was performed. The drawing results proved that one to one translation from gel casting (films) to solution spinning (fibers) process is not straightforward. And also suggested that optimization of the drawing conditions of fibers can possibly lead to achieve expected maximum draw ratios.","ultra high molecular weight polyethylene; mechanical properties; solvent quality","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:00a47c4a-73d8-4c41-a9dc-f9fdc35e4fce","http://resolver.tudelft.nl/uuid:00a47c4a-73d8-4c41-a9dc-f9fdc35e4fce","Cost-sensitivity Analyses for Gearbox Condition Monitoring Systems Offshore","van den Broek, T.","van Bussel, G.J.W. (mentor)","2014","To compete more successfully with other sources of energy, a decrease in the costs of offshore wind energy needs to be achieved. Operation and maintenance costs represent a large share of these costs. In order to reduce these costs new developments and strategies are considered for operation and maintenance of wind turbine components. Condition monitoring systems (CMSs) could be a vital tool to decrease these costs, especially for expensive components such as a gearbox. This thesis focusses on the gearbox as it is the component, with one of the highest downtime per failure and failure costs. A literature study reveals that the replacement of a gearbox offshore might lead to months of downtime and costs might sum up to one million euro for a 6 MW wind turbine. In order to prevent such high costs, CMSs are assessed in this thesis. CMSs comprise of sensors providing data, which reflects the health status of the component. This data is subsequently analysed by a data-mining technique, capable of detecting trends and anomalies to predict upcoming failures. If the system is sufficiently accurate, a large failure can be prevented, which leads to significant savings in the lifetime gearbox maintenance costs A cost-benefit study is performed to determine the required performance of a CMS in order to be profitably implemented in an offshore wind turbine. The CMS performance is described by two parameters: one reflecting the ability of the system to prevent large gearbox failures, and a second parameter describing its ability to prevent waiting downtime, caused by weather window waiting time, spare part logistics and vessel mobilisation. Based on Monte Carlo simulations, the gearbox maintenance costs are quantified over the wind turbine lifetime. Subsequently a sensitivity analysis is performed. Results show that differences in gearbox failure rate and wind farm distance significantly affect the maintenance costs. Hence to break-even different performance requirements of the CMS are necessary. The model reveals that a system, capable of preventing large failures and/or preventing waiting downtime, can reduce the lifetime maintenance costs to a great extent. The actual performance of a CMS, needed to break-even, can be considered low, as the condition monitoring costs are in no proportion to the total gearbox maintenance costs and thus the potential revenue of the CMS.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","Sustainable Energy Technology","",""
"uuid:4a5cacb7-b4dd-4665-b697-c53427b3bed6","http://resolver.tudelft.nl/uuid:4a5cacb7-b4dd-4665-b697-c53427b3bed6","Design, Implementation and Verification of the Attitude Determination and Control Algorithms for the DelFFi Satellites","Haghayegh, M.","Guo, J. (mentor)","2015","","ADCS Satellite","en","master thesis","","","","","","","","","Aerospace Engineering","Spaceflight","","Space Systems Engineering","",""
"uuid:98c55fe3-cd59-4c61-817e-9caa6ac835b6","http://resolver.tudelft.nl/uuid:98c55fe3-cd59-4c61-817e-9caa6ac835b6","Interplanetary Trajectory Design using Dynamical Systems Theory","Van der Ham, L.","Noomen, R. (mentor)","2012","Instead of the two-body problem commonly used in interplanetary trajectory design, also three bodies can be considered: the satellite, a planet and the Sun. Knowing that planet and Sun orbit one another in almost circular orbits, and the mass of the satellite is negligible compared to the mass of these bodies, the model of the circular restricted three-body problem (CR3BP) can be used. Dynamical Systems Theory (DST) concerns itself with the analysis of differential equations, as the equations of motion in the CR3BP are. After finding the Lagrange libration points, the region about these points can be examined. Periodic orbits and asymptotic orbits are two of the four types of motion in these regions. The asymptotic paths form manifolds and create a natural highway to travel from and to the area around equilibrium points. Extending the manifolds far from the periodic orbits for many Sun-planet systems shows a network of manifold tubes, which is referred to as the Interplanetary Superhighway and may be an energy efficient way of transfer. Zooming in on two consecutive Sun-planet systems the transfer from one to another can be examined. The actual four-body problem is approximated by two coplanar coupled three-body problems. The high-trust maneuver requiring the minimal instantaneous velocity increment, to get from one CR3BP to the next, is to be found. On the intersection of manifolds, different positions for executing the maneuver are available. Furthermore the mutual geometry of the two systems changes with the chosen epoch. So for changing place and time of the maneuver, the minimal velocity increment is computed and analyzed. Finally the optimal maneuver is used in the design of a mission; a transfer from one planet to another.","space; trajectory design; dynamical systems theory; circular restricted three-body problem; interplanetary space flight","en","master thesis","","","","","","","","2012-03-20","Aerospace Engineering","Earth Observation and Space Systems","","Astrodynamics & Satellite Systems","",""
"uuid:595a974c-e1fd-4006-850f-3a1fe2e99c5a","http://resolver.tudelft.nl/uuid:595a974c-e1fd-4006-850f-3a1fe2e99c5a","Dynamic Modeling and Controller Design of a Novel Marine Energy Converter","Malvezzi Campeggi, F.","van Bussel, G.J.W. (mentor); Vellone, R. (mentor); Ashuri, T. (mentor)","2010","","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2dfae5a6-809e-484d-8b3e-ebd146d891f3","http://resolver.tudelft.nl/uuid:2dfae5a6-809e-484d-8b3e-ebd146d891f3","Quantitative risk analysis of unguided rocket trajectories","Engelen, F.M.","Mooij, E. (mentor); Verhoeven, C. (mentor); Ambrosius, B.A.C. (mentor)","2012","These days more and more rockets are developed by companies, students and other amateurs. To assess the safety of these rockets, a method is necessary to estimate the risk of these vehicles quantitatively. Because tools to do so are not freely available, the goal of this thesis is to research methods to quantitatively estimate the risk of nominal flight of unguided rockets. The first step to do so, is to develop a trajectory simulator. To incorporate the effect of wind (weather cocking) and spinning, it is necessary to develop a simulator with three translational degrees of freedom, and three rotational degrees of freedom. The position and velocity of the rocket are described in a Cartesian coordinate system. To prevent singularities in the orientation, quaternions are used to describe the orientation of the rocket. To propagate these through time, classical equations of motion for a rigid body can be used. To do so the impulse thrust force and the jet damping moment are considered as an external force and external moment. The gravity force, the aerodynamic force, and the aerodynamic moment are the other external influences. To calculate these, the Earth is modeled as a flatted sphere (both shape and gravity field) with a US 1976 standard atmosphere, and a tabulated wind profile. The aerodynamic forces and moments are calculated based on this environment and a limited set of aerodynamic coefficients, obtained from the Missile Datcom 97 program. Because the problem’s nature it is not solvable analytically. Furthermore, in some parts of the flight the state rocket’s state changes rapidly, while in others parts the system behaves very smoothly. Therefore a Runge-Kutta-Fehlberg 56 variable time step integrator is used to solve the equations of motion numerically. As a result of this decision it is necessary to implement an event handling algorithm to execute discrete behavior (e.g. stage ignition) at the right time. To validate the in C++ developed program ROSIE, a small amateur rocket’s flight (2m long, apogee at 1 km) is simulated. The results show similar behavior as observed in the real flight data of the simulated rocket, indicating that the simulator is valid for the simulation of small amateur rockets. When comparing a single simulated impact point with a measured impact point, they will most likely not coincide. This can be explained by errors in the flight’s modeling, and can be due to randomness in what is simulated. By stating that these errors are due to uncertainties in the analysis, and modeling these uncertainties as random (input) variables, the result of the analysis will also be a random variable. An advantage of such a variable is that the result is not a single point, but a probability distribution. This distribution can be used to determine the risk to each individual, or the area which needs to be evacuated. To determine the probability distribution different methods are used. These methods can be grouped in parameterized and non-parameterized methods. With parameterized methods, a known type of probability distribution is used to model the dispersion of the impact point. To estimate the parameters of this distribution only a limited number of simulation runs is necessary. The downside of using a parameterized method is that the problem is simplified, in such a way that it can be modeled by a known distribution function. This introduces errors in the estimation of the risk. The alternative is to use a non-parameterized method. The method used is Monte Carlo simulation. To determine the probability of impact in a certain area, the trajectory simulation is run a large number of times. Because part of the input is random, each estimated impact point will have another location. By counting the number of impact points which landed in the sub domain, and dividing this by the total number of simulations, the probability of impact in that specific area can be calculated. Properties of Monte Carlo simulation can be used to specify a confidence interval for the calculated answer. By increasing the number of simulations the accuracy of the answer can be increased. The downside of Monte Carlo simulation is that many trajectory simulations are necessary, making it a very computational time intensive method. For the parameterized methods two different types of probability distributions are used, being the bivariate normal distribution, and the mixture model variant. This variant combines multiple bivariate normal distribution into a new more complex model. To estimate the parameters of these distributions, they are fitted through the data generated with trajectory simulator. This data is generated with different sampling schemes. Four different schemes are used. One-at-a-time sampling and orthogonal array sampling are only valid for the bivariate normal distribution, while the random sampling and Sobol sequence sampling scheme can be used for both. To compare the different methods, they are applied to a preliminary design of the Stratos II rocket. This is a large amateur rocket (5m) which will fly the 50 km in the near future. As a starting position for the comparison, 50000 random trajectories are simulated as benchmark data (Monte Carlo simulation). Comparing the parameters of the bivariate normal distribution obtained with this simulation and with 85 one-at-a-time samples shows a differences of 15 to 30 %. When 81 orthogonal array samples are used, this difference is reduced to less than 10%. With the same number of samples the found accuracy of Sobol sequence sampling is similar to that of the orthogonal arrays, but an advantage of Sobol sampling is that any number of samples can be selected to reach the desired accuracy. Random sampling cannot be used at a low number of samples. Orthogonal array and Sobol sampling have a better performance than one-at-a-time sampling, but are also more complex in their use. Which method to use, depends on the application. The second aspect which is benchmarked, is how accurate the parameterized method estimated the probability of impact at two specific locations. Comparing the probability (and its confidence interval) obtained directly from the Monte Carlo simulation with the one obtained from the bivariate normal distribution (based on 50000 random points) shows that the latter method can be either a factor 2 to 3 too conservative, or too optimistic. Whether or not this is acceptable depends on the applications. Using a mixture model, consisting of only two bivariate normal distributions, already shows significant improvements. Increasing the number of components does increase the accuracy, but also the sensitivity to outliers. Therefore it is not wise to use more than 5 components. To determine the influence of each individual parameter on the probability distribution (the footprint), different sensitivity methods are applied. To study non-linear effects and interactions, the set of parameters is reduced with the Morris elementary effect screening method. Applied regression based sensitivity analysis shows that the dispersion in range direction consists mainly of linear contributions. More specifically, these are the contributions due to uncertainty in thrust of the second stage, the drag coefficient and the atmospheric density. The dispersion in cross range direction depends for a significant part (> 10%) on non-linear contributions and interactions between parameters. This explains the error when modeling the probability distribution with a bivariate normal distribution. For the studied case, the two parameters which have the most influence on the dispersion in cross range direction, are the thrust misalignment of the first stage and the center of mass offset. The Stratos II is simulated to be launched from Esrange Space Center. Comparing the found footprint with the allowed impact area of Esrange shows that it is unlikely that the studied design is allowed to be launched from this site. By improving the design, it might be possible to reduce the size of the footprint in such an extend that it will fit if nominal flight occurs. Unfortunately, due to the experimental nature of the rocket, Esrange will likely demand that for non-nominal flight too, the footprint has to be in the allowed impact area. It is very unlikely that this is possible for a rocket flying to 50 km.","Rocket trajectory Stratos simulation","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:73e8dd75-207b-4bfc-aaa5-bcd4fa3e0242","http://resolver.tudelft.nl/uuid:73e8dd75-207b-4bfc-aaa5-bcd4fa3e0242","Estimating an LPV model of neuromuscular admittance with grip force as scheduling parameter","Pronker, A.J.","Abbink, D.A. (mentor)","2016","Development of adaptive haptic shared control system requires understanding of the adaptive nature of the driver’s neuromuscular system. In this study, linear parameter varying modeling techniques are proposed to identify changes in the admittance of the driver’s arm. The admittance describes the relation between the torque applied to the steering wheel and steering wheel angle output. By conducting two experiments it is investigated whether grip force applied to the steering wheel serves as an appropriate scheduling variable for a LPV model. In our approach, first tracking tasks with torque perturba- tions applied to the steering wheel are performed with varying boundary widths to evoke changes in admittance. The relation between grip force and admittance is investigated by estimating neuromuscular stiffness and damping parameters and measuring the force applied to the steering wheel using pressure gloves. An LPV model is identified by linear interpolation between LTI models identified for each condition. Second, a driving task is performed in a fixed-base driving simulator to analyze the variance in grip force and changes in admittance between wide and narrow roads. The results of the driving task are used to assess the validity of the LPV model during driving tasks. It was found that the stiffness and damping parameters varied proportionally with the grip force. Although small variations in grip force levels are found between subjects, it is concluded that grip force is an appropriate scheduling variable for an LPV model. The relation between grip force and admittance was similar during driving tasks compared to the tracking tasks. The derived LPV model accurately describes the changes in the neuromuscular system over the range of grip force variations observed during the driving task. For further validation of the LPV model in the time-domain it is recommended to use time- varying boundary tasks.","neuromuscular admittance; time-varying; grip force; LPV; driving behavior","en","master thesis","","","","","","","","","Aerospace Engineering","Control & Simulation","","","",""
"uuid:93d3650d-e6d1-49b5-b8c7-6c5b0bebfd9b","http://resolver.tudelft.nl/uuid:93d3650d-e6d1-49b5-b8c7-6c5b0bebfd9b","Earth-Moon Transfer Orbits","Zuccarelli, V.","Noomen, R. (mentor); Ambrosius, B.A.C. (mentor)","2009","This work is part of the ESA-project, that wants a preliminary study about the feasibility of building a permanent base on the south pole of the Moon, before July 1st 2020. Moreover after having completed the building phase, the maintenance has to be guaranteed for at least another ten years during the operational phase. The problem is tackled considering only the orbit design point of view. The Space Trajectory Analysis (STA) software has to be used to perform the entire mission, which is a requirement imposed by ESA. Actually this is a thesis group work, that has been split in three different parts, one per student: ascent (since the launch until the parking orbit is reached), transfer (until a lunar parking orbit is obtained) and landing phase. In this thesis the central part is investigated. Since the best transfer orbit has to be found, all the possible options to go from the Earth to the Moon have been studied and analyzed: two-body problem, three-body problem and low-thrust trajectories. Therefore the Lambert’s problem has been tackled by using impulsive manoeuvres and low-accelerations arcs (modelled by the Exposins theory). In both cases a global optimizer has been used to find the best orbit transfer. For these two kinds of trajectories the STA Interplanetary Module and the STA Interplanetary Low-thrust Module have been used respectively. The third option is represented by heteroclinic manifolds trajectories, able to connect the Sun-Earth and the Earth-Moon 3-body systems. To that purpose the STA 3-Body Module has been developed to compute trajectories exploiting this model. Also in this case a global optimizer has been used to get the best solution. In all cases the total ?V has been the objective function. Actually to build a lunar base the most relevant parameter is the payload mass that cab be delivered into a lunar orbit per each launch. The TOF has been strongly considered only for the trajectory design of manned missions, and, in case of similar performance, for cargo missions too. The computations turned out that the Ares V launcher is the only one able to transfer enough mass per launch in order to build the lunar base, and both high-thrust and 3-body trajectories can be selected. Actually 3-body trajectories allow to transfer circa 4 tons more per launch, for this reason they have been widely used for the building phase. Furthermore the Ares V is the only launcher that can accomplish successfully manned missions. In this case only high-thrust trajectories have been considered, since the TOF becomes an important factor to take into account. Low-acceleration trajectories seemed to be well-promising, but a numerical integration of the trajectory (not included in the STA Interplanetary Low-thrust Module) is required in order to better evaluate this kind of orbit. This was outside the scope of this particular study.","moon","en","master thesis","","","","","","","","2009-12-08","Aerospace Engineering","SpE/ AS","","","",""
"uuid:565327fc-c023-4a04-ba7b-7d9a0671a66e","http://resolver.tudelft.nl/uuid:565327fc-c023-4a04-ba7b-7d9a0671a66e","Sediment classification using Sub-bottom profiler","Saleh, M.","Simons, D.G. (mentor); Snellen, M. (mentor); Wunderlich, J. (mentor)","2011","Sub bottom profilers are commonly used as mapping tool for the seafloor and sub-bottom structure in the upper few meters of the seafloor. Their recent enhanced performance in terms of resolution adds the potential to classify the sediment layers as well. In this research, the seabed surface and sub layers classification are investigated using model based techniques. The remote sediment classification technique of the seabed surface is achieved by matching the back scatter measurements to the predicted backscatter intensity of the model. The model simulates the returned signals of a monostatic sub bottom profiler operating at 100 kHz. The back scattering strength in the angle domain is estimated using the APL-UW backscattering model. The matching procedure was applied on averaged echo envelopes performed by Hilbert transform. The averaging process is essential to reduce the stochastic variability of the acquired data. The sub layers data was obtained by operating frequencies of (5, 10 and 15 kHz). The layer classification was achieved by estimating the geoacoustic parameters such as reflectivity and impedance contrast. Two techniques were investigated based on a reflectivity model. The first technique is an extension work of D.Simons [11] which aims to estimate the reflection coefficients via the received and transmitted energy ratio. The second technique is an implementation of a similar approach but applies the attenuation on the received frequency components in place of the nominal components. Both models accounted for energy propagation and its corresponding geometrical and sediment attenuation losses. The classification techniques were carried out to a dataset that was acquired in the Baltic Sea near Rostock in 2004. The acquired dataset is characterized by various bottom types such as mud, sand and coarse sediments. The general description of the acquired areas was used as a reference for the final results. Due to the lack of core samples, the classification was evaluated by comparing the results of the backscatter to the energy model. The results were consistent with the general description of the dataset. However, the matching process of the backscatter model is a cumbersome and very sensible to the envelope averaging technique. Averaging the reflected signals from the soft sediments has to ensure to preserve the surficial and volume back scatter information. On the other hand, at rough surfaces, the late arrivals are likely to be irregular reflections or noise that has to be averaged to avoid ambiguous results. The initial results of sub layers reflection models were consistent with the data description. However, due to the high resolution of the sub bottom profile, the computation procedure can easily fail by missing sub layers. In order to reduce the probability of missing layers, an overlapping window concept was implemented, where the reflection coefficients are estimated at shorter intervals. The methods investigated here leaves room for further optimization through model adjustment such as signal interference, backscatters and error propagation.","","en","master thesis","","","","","","","","","Aerospace Engineering","Geomatics","","","",""
"uuid:043ce106-19d6-497a-b8d9-4e77a5d02fd2","http://resolver.tudelft.nl/uuid:043ce106-19d6-497a-b8d9-4e77a5d02fd2","Space Missions with SOKS: The First Complete Overview of Space Missions with Sub One Kilogram Spacecraft Launched in the Past (1957-2016)","Djordjevski, D.","Sundaramoorthy, P.P. (mentor)","2017","The success of CubeSat, after 2005, resulted in bright future expectations of Spacecraft with a mass below one kilogram. Although these spacecraft are usually known as Pico and FemtoSat, their ambiguous nature and inconsistent use in literature resulted in the use of an alternative, namely Sub One Kilogram Spacecraft, or simply said SOKS. Slogans like ‘Smaller, Cheaper, Faster’ or ‘Do More with Less’ are easy to encounter in the proposed concepts of Space Missions with SOKS, as well as statements like ‘Think Big, Fly Small’ and ‘The next big thing in Space is something small’. However, the expectations are only based on these concepts and are in contrast with the reality, which show a limited record of launches. What would the expectations be, based on Space Missions with SOKS from the past? Would they foresee the same bright future or would they state the opposite? The search for a scientific motivation of these expectations resulted in the first complete overview of Space Missions with SOKS that were launched in the past. This thesis provides a journey through time from the controversial West Ford Needles, at the start of the Space Age, to beyond the first crowd funded Space Mission known as KickSat 1. It also resulted in a unique dataset of Space Missions with SOKS. The analysis thereof provided new insights with a clear outcome. A selection of these graphical representation is presented and discussed in this report. This thesis provides the latest update regarding, for instance, the applications and success rates, as well as the countries that have their SOKS Missions launched throughout history. The end of this thesis addresses the expectations based on these results.","Sub One Kilogram Spacecraft; SOKS Space Missions; Space Missions with SOKS; Unfeatured SOKS; Featured SOKS; Smart SOKS","en","master thesis","","","","","","","","2022-03-10","Aerospace Engineering","Space Engineering / Space Systems Engineering","","Space Flight","",""
"uuid:447d7c7b-0b2f-4600-b452-1aec8e35fb12","http://resolver.tudelft.nl/uuid:447d7c7b-0b2f-4600-b452-1aec8e35fb12","A Methodological Approach for Enabling the Analysis and Assessment of Multidisciplinary Design Workflows","Schuurman, M.C.","La Rocca, G. (mentor); van Gent, I. (mentor)","2017","","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Flight Performance and Propulsion","",""
"uuid:e7e16208-8b9a-457e-9bdc-87e65e4c9135","http://resolver.tudelft.nl/uuid:e7e16208-8b9a-457e-9bdc-87e65e4c9135","Horizontal Tailplane-Tip Mounted Tractor Propeller Interaction Effects","Candade, A.A.","Sinnige, T. (mentor); Veldhuis, L.L.M. (mentor)","2015","Advanced propeller propulsion systems potentially provide a significant reduction in fuel burn compared to traditional turbofans. An alternative to the conventional aft-fuselage mounted pusher layout is the horizontal tailplane-tip mounted tractor propeller concept. The aim of this thesis is an experimental investigation of the aeroacoustic and aerodynamic interaction effects of the tailplane-tip mounted tractor propeller configuration, including the effects of elevator deflections. The experimental study was conducted at TU Delft’s Low Speed Laboratory in the Vertical Tunnel and the Low Turbulence Tunnel with two different models. From the aeroacoustic study, it was concluded that the installation of the pylon behind the propeller affects both the directivity and the tonal levels of the propeller noise field, with the broadband acoustic levels remaining unchanged. It was determined that the overall sound pressure level (SPL) across the range of directivity angles considered is inversely proportional to the propeller-pylon spacing. For a spacing of 50% propeller diameter, the overall SPL was comparable to the case of the isolated propeller. A unique characteristic of installation of the pylon was the development of a trough in the directivity for an observer position in the pylon plane caused by the cancelling of the steady noise field by unsteady blade loading noise. This arises due to inflow distortion due to potential effects caused by the pylon. This unsteady blade loading is a function of the propeller-pylon spacing, and hence the levels in the trough decrease with decreasing propeller-pylon spacing. For directivity angels in the pylon plane, for spacing below 30% of the propeller diameter, the unsteady loading is further influenced by the elevator deflection and was the main mechanism of the interaction noise. For propeller-pylon spacing’s above 30% of the propeller diameter, the interaction of the slipstream (either the propeller noise field, or the slipstream impingement) with the elevator was determined to be the main interaction mechanism. From the PIV and performance evaluations, it was concluded that for the given propeller-pylon spacing (43% and 85% propeller diameter), there was indeed negligible upstream interaction effect due to the trailing pylon, including the case of the deflected elevator Pylon loads obtained from an external balance showed that for symmetric inflow conditions, operation of the thrusting propeller increased elevator effectiveness by 20% compared to the case with no propeller present. A numerical simulation using XROTOR was used for the validation of the test data and had a relative error of 3% with the experimentally evaluated propeller thrust for the lowest advance ratio. A slipstream propagation model based on the computed propeller induced velocities showed acceptable trends when compared to the experimentally determined induced propeller velocity profiles. However, the numerical model overpredicts the velocity profile in the tip region, owing to the tool’s limitation in predicting stall at the blade tip. A VLM based numerical analysis which included the effects of the propeller slipstream, was able to predict the pylon lift to within 3% of the lift computed from the surface pressure measurements, but failed in the prediction of the drag of the model.","propeller; propulsion integration; vortex interactions; aeroacoustics","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","Flight Performance and Propulsion","",""
"uuid:0f79480b-e447-4828-b239-9ec6931bc01f","http://resolver.tudelft.nl/uuid:0f79480b-e447-4828-b239-9ec6931bc01f","Up! How to Launch and Retrieve a Tethered Aircraft","Bontekoe, E.","Voskuijl, M. (mentor); Van Bussel, G.J.W. (mentor); Pavel, M.D. (mentor); Sieberling, S. (mentor)","2010","The basic model of the principle of crosswind power as described by Miles M. Loyd in 1980 (Loyd, 1980), promises a high energy revenue from airborne wind energy. With a growing awareness of the need of sustainable energy resources and the current technological possibilities, different initiatives are undertaken to harvest the energy of wind at higher altitudes. One of these initiatives is the Powerplane, which makes use of a glider type aircraft with a wing span of 36 meters for producing 1 MW of electric power. The aircraft flies patterns in the sky such that it produces a high tension in the connecting tether. The system generates power as the tether is unwound from a drum located at the ground under this high tension. When the tether is fully unwound, the aircraft performs a dive while the tether is quickly retrieved with a minimum tension. The difference in tension during retrieval and unwinding allows net energy to be generated. Before the 1 MW Powerplane can be put on the market as a working system, several technological hurdles must be taken. A conventional wind turbine is always remotely situated at its operational altitude as soon as it is installed. On the contrary, the Powerplane needs a method to get there. Therefore one of the main design challenges is the step between an idle state on the ground, and generating energy at operational altitude. This challenge is the main objective of the research done in this thesis: to find out how the aircraft can be launched and retrieved such that the Powerplane will be a competitive system for wind energy generation. There are many different ways for doing this, but which way is most feasible? To answer this question, first of all the main requirements a launch and retrieval system has to comply with are outlined. A functional analysis lead to different design options, of which the most interesting options where analysed more extensively by various methods. Combining promising design options gave three concepts. One concept based on buoyancy, a concept making use of propeller thrust and one which uses a rotational platform to launch the aircraft. Analysing these concepts in a trade-off resulted in abandoning the buoyancy concept, but the other two required more research. This resulted in an improvement of the propeller thrust concept by combining it with a circular runway. The operating principle of the rotating platform concept is analysed by means of computer simulations.Even though the results of the simulations where promising, they where not convincing. Before a definite decision on the concepts can be made, more research is required. The effect of the added weight of the propeller thrust concept should be determined by studying the Powerplane concept in general. The concept of the rotational platform needs to be investigated more to make sure that the operational altitude can be reached without additional equipment. Nevertheless, the research outlined in this thesis and the recommendations made, provide a firm basis to find the optimum solution for launching and retrieving the aircraft. I hope the content of this research will help to make the concept of Airborne Wind Energy a step closer to becoming a world wide success.","Airborne Wind Energy; Windenergy","en","master thesis","","","","","","","","2013-07-09","Aerospace Engineering","FPP","","","",""
"uuid:78337358-beee-4585-bb23-9193e7270652","http://resolver.tudelft.nl/uuid:78337358-beee-4585-bb23-9193e7270652","Numerical Simulation of a Lean Premixed Hydrogen Combustor for Aero Engines","Veiga Lopez, F.","Perpignan, A.A.V. (mentor); Gangoli Rao, A. (mentor)","2016","The effect of aviation emissions on human-induced climate change has become a major concern in the last decades. The reduction of emissions, such as CO2 and NOx, is an important matter because of the predicted increase of the aviation market in the future years. The application of alternative fuels, such as hydrogen, and new combustion methods (e.g. lean premixed) are two of the main trends in order to reduce civil aviation emissions. The AHEAD (Advanced Hybrid Engines for Aircraft Development) project presented a novel hybrid engine concept. The proposed innovative design uses two combustion chambers. The first is a cryogenic fuel combustor, conceived to operate with liquid hydrogen or liquid natural gas, followed by an inter-turbine flameless biofuel combustor. In the present thesis, the lean premixed hydrogen combustor designed in the AHEAD project was simulated by applying a Computational Fluid Dynamics (CFD) method. The main objective of the present study is to find a set of CFD models which better characterize the named combustor, using exclusively the RANS (Reynolds Averaged Navier-Stokes) approach. Both a reactive and non-reactive approaches were followed. The results obtained were analysed and compared with experimental data. The RANS k-ε realizable turbulence model provided satisfactory qualitative results for the non-reactive case. The model predicted the characteristic features of the flow field obtained at swirling premixed combustors, such as the central and outer recirculation zones, the vortex breackdown, etc. The reactive flow field was not well characterized by the selected combustion models (e.g. Flamelet-Generated Manifold, Eddy Dissipation Concept). The main problem was found to be the mixing pattern predicted by the set of models used in the study. The RANS turbulence models applied were not accurate enough to obtain a satisfactory hydrogen-air distribution at the mixing area of the combustor. Further analysis is advised, adding a more detailed CFD approach such as the Large Eddy Simulation.","","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","009#16#MT#FPP",""
"uuid:ed61399b-a656-4126-99b6-14461bfb09f4","http://resolver.tudelft.nl/uuid:ed61399b-a656-4126-99b6-14461bfb09f4","Disbond arrest in fibre metal laminates","Hangx, R,","Rans, C.D. (mentor); Kruse, T. (mentor)","2017","In the development of materials used for constructing aircraft, progress has been made in the production, certification and implementation of materials such as Carbon Fibre Reinforced Polymer (CFRP) and Glass Laminate Aluminium Reinforced Epoxy (GLARE). The state-of-the-art in joining techniques however, has not changed much: fastening is still the current used method for high load transfer (HLT) joints. Unfortunately, fastening is associated with high fatigue sensitivity due to the need for holes in the joined materials, causing stress concentrations and a highly concentrated load introduction. Using bonding for HLT joints would alleviate this fatigue sensitivity by continuous load transfer over the bonded area. Currently, certification of these bonded major loadpath joints is only allowed if the design of bond-line secures a limitation of the maximum disbond size originating from manufacturing anomalies or in-service impact events. In order to meet this requirement, disbond arrest features (DAFs) need to be implemented in the bond-line. As a spin-off from the BOPACS (Boltless Assembling of Primary Aerospace Composite Structures) project, where fasteners are used for disbond arrest, the transferability of this design strategy in GLARE is investigated. The fatigue sensitivity of the metallic bonded surface in GLARE in combination with the implemented fasteners inside the bonded area prove to affect the disbond arrest performance to a large extent. A unique combination of fatigue crack growth (FCG), adherend delamination and adhesive disbonding is observed in the tested configurations, detrimental to the DAFs intended use. In the process, a qualitative in-situ disbond monitoring system is developed and verified. Additionally, the root causes of the observed failure mode and the subsequent damage progression are identified. By identification of the one-off damage progression characteristics, new DAF designs are proposed for the certification of bonded HLT joints in GLARE.","ultrasonic testing; fibre metal laminate; GLARE; secondary bonding; high load transfer joint; damage tolerance; disbond; delamination; fatique; fatique crack growth; certification; wide single lap shear; non-destructive inspection; digital image correlation","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:b4b1fe9c-acb6-4e2b-adc6-5324dfbaf51c","http://resolver.tudelft.nl/uuid:b4b1fe9c-acb6-4e2b-adc6-5324dfbaf51c","Feasibility study of a novel load alleviation system on the UH-60A Blackhawk helicopter","Verhagen, M.R.","Voskuijl, M. (mentor)","2015","","helicopter; structural load alleviation system; SLA; tailplane; horizontal stabilizer; Flightlab; UH-60A; Blackhawk; agility; safety; flightpath bandwidth","en","master thesis","","","","","","","","2016-08-06","Aerospace Engineering","Aerospace Design, Integration & Operations","","Flight Performance and Propulsion","",""
"uuid:b646738b-4a6f-4fcb-b8ee-2724afeeb8c7","http://resolver.tudelft.nl/uuid:b646738b-4a6f-4fcb-b8ee-2724afeeb8c7","A study on the temporal evolution of bainitic ferrite in medium Mn steels using in-situ HT-LSCM","Sainis, S.M.","Van der Zwaag, S. (mentor)","2017","Bainite is an interesting solid-state transformation in steels and a detailed understanding of the mechanism and phase transformation kinetics is of fundamental interest as well as technological importance. In this study, the kinetics of austenite to bainitic ferrite is studied through in-situ high temperature laser scanning confocal microscopy (HT-LSCM). Quantitative measurements of the evolution of microstructure is performed by digital image processing techniques. These quantitative results have been compared with predictions of existing phenomenological models developed for bainite to study the temperature and composition dependence. In the temporal evolution of microstructure, nucleation and growth phenomenon have been investigated separately. Due to the complex characteristics of bainite transformation, two approaches exist for modelling the transformation kinetics based on different assumptions of the underlying mechanisms at play. Two classical nucleation theory based models are studied- Offerman et al model for austenite to ferrite transformation and Quidort and Bréchet model for bainite. In the framework of the displacive theory of bainite transformation, Ravi et al model is investigated. Growth of individual bainitic ferrite plates and overall austenite to ferrite growth is investigated through the study of plate growth rates and temporal evolution of bainitic ferrite fraction respectively. Quantitative predictions of three growth models: local equilibrium, paraequilibrium and Gibbs Energy Balance model have been compared with experimental observations. Additionally, global kinetics of bainitic ferrite fraction is measured experimentally using dilatometry.","","en","master thesis","","","","","","","","","Aerospace Engineering","Novel Aerospace Materials","","","",""
"uuid:05dfa54b-a774-4fdc-ad9b-f125f408784c","http://resolver.tudelft.nl/uuid:05dfa54b-a774-4fdc-ad9b-f125f408784c","Design and Evaluation of a Haptic Aid for Training of the Manual Flare Manoeuvre","Deldycke, P.J.","Pool, D.M. (mentor); Van Paassen, M.M. (mentor)","2017","","","en","master thesis","","","","","","","","2022-04-04","Aerospace Engineering","Control & Simulation","","","",""
"uuid:9ad6db51-5d2b-4680-b250-72b03ccc5fbb","http://resolver.tudelft.nl/uuid:9ad6db51-5d2b-4680-b250-72b03ccc5fbb","Performance Evaluation in Obstacle Avoidance","Nous, C.W.M.","De Croon, G.C.H.E. (mentor)","2016","No quantitative procedure currently exists to evaluate the obstacle avoidance capabilities of robotic applications. Such an evaluation method is needed for comparing different methods, but also to determine the operational limits of autonomous systems. This work proposes an evaluation framework which can find such limits. The framework comprises two sets of tests: detection tests and avoidance tests. For each set, environment and performance metrics need to be defined. For detection tests such metrics are well known. For avoidance tests however such metrics are not readily available. Therefore a new set of metrics is proposed. The framework is applied to a UAV that uses stereo vision to detect obstacles and three different algorithms to calculate the avoidance manoeuvre.","Obstacle Avoidance; Evaluation Framework; Complexity Metrics","en","master thesis","","","","","","","","2016-10-01","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:4f31fe3b-156e-4fe1-accb-2305c844cad5","http://resolver.tudelft.nl/uuid:4f31fe3b-156e-4fe1-accb-2305c844cad5","Free Route Airspace for Route Optimization","Braga de Carvalho Vieira Pereira, J.P.","Martins de Matos Ventura, R. (mentor); Melo, A. (mentor)","2015","These thesis is the result of the study of the possibility of expansion of the two existing Free Route Airspaces (FRAs) in the portuguese airspace, creating a joint FRA, where the goal is to optimize the routes passing this airspace, making it more efficient and consequently more competitive. At a later stage, is also analyzed an union between this joint FRA with the Flight Information Regions (FIRs) of Morocco and Asturias. In addition, and working as an intermediate step towards the criation of a joint FRA, the localization of the current Navigation Points of the respective FIRs is analyzed, aiming to evidence and correct possible inefficiencies. The results have shown, that it is possible to make improvements in the current scenario, reducing the distance, time and fuel spent, and consequently reduce the current costs. However, the implementation of this new scenario can only be achieved through a total commitment and cooperation between the parties involved in restructuring is airspace.","Air Traffic Management; Free Route Airspace; Route Optimization; Flight Information Region","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Operations","","Double Degree Programme IST-TU Delft","",""
"uuid:d0662c3e-a884-4ce1-a484-065c962b2b67","http://resolver.tudelft.nl/uuid:d0662c3e-a884-4ce1-a484-065c962b2b67","Testing of an Optimised Data Bus for Pico- and Nanosatellites","van der Linden, S.P.","Bouwmeester, J. (mentor)","2017","The definition of the CubeSat is already nearly two decades old. This results in the trend that a large fraction of CubeSat missions are leaving the domain of (educational) technology demonstration and entering that of commercial applications. Therefore a larger focus is put on the reliability and compatibility of commercial of the shelf systems and the spacecraft containing them. One subsystem that is more or less fixed since the first CubeSat missions is the serial data bus. This internal network is essential for interconnecting subsystems. However, recent investigations have shown that the industry standard I2C must be re-evaluated due to performance and reliability restrictions. The research contained in this thesis sets off to evaluate these characteristics of other data bus standards to propose a possible future-proof data bus architecture. By splitting up the analysis cases into two parts, the choice and design of both parts can be optimised. The Telemetry and Command (TC) bus carries essential commands and housekeeping data between systems, while the Payload (PL) bus is dedicated to high speed bulk data transfers. An initial requirement-based selection of bus standards reduced the selection of standards to several options for both bus cases; for the TC bus, I2C, CAN and RS485 were selected. For the PL bus, CAN, RS485, SPI and USB were selected. The selected standards were all implemented in a data bus testing suite, comprising of up to nine simulated subsystems providing pseudo data to be communicated over the bus. Measurements were conducted of the buses' power consumption and data rates in several realistic test cases. Furthermore, the complexity and ability to withstand noise and voltage transients were evaluated. Ultimately, this resulted in a recommendation of using RS485 in future TC bus configurations and SPI in the PL bus configurations. However, this conclusion must be regarded a recommended direction of future research for several reasons. Firstly, more investigations are needed in the ability of these buses to work when subjected to large amounts of noise and other extreme environments. Secondly, the performed trade-off does not apply weighting to its criteria, as these can and will vary wildly for different missions. Finally, the test setup was limited in terms of processor ability for the PL bus case. These specific tests should therefore be redeveloped with more powerful equipment, allowing an even more realistic simulation of future CubeSat subsystems.","CubeSat; PocketQube; data bus; CDHS; delfi-pq; DWire","en","master thesis","","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:abf4adc9-b198-4cb1-a338-64567fc62521","http://resolver.tudelft.nl/uuid:abf4adc9-b198-4cb1-a338-64567fc62521","Lamb Wave Propagation in Sandwich Composite Structures for the Detection of Impact Damage","Aaij, E.","Martinez, M.J. (mentor)","2016","Lightweight composite sandwich structures are particularly susceptible to impact damage. Barely Visible Impact Damage (BVID) is known to affect the short and long term load bearing capacities of composite structures. Active acoustic Structural Health Monitoring (SHM) systems have the potential to detect such damages before they lead to structural failure, and could thus be applied in a condition based maintenance approach for the DragonFly fuselage. This study was aimed at increasing the level of understanding on the propagation of ultrasonic (Lamb) waves through sandwich composite media and its response to the DragonFly fuselage structural integrity. These two aspects were combined to arrive at a theoretical prediction on the influence of BVID on the through-transmitted signal in an active acoustic SHM system with a pitch-catch setup. The propagation mode and impact response were verified experimentally. A Finite Element (FE) model was created to verify the predictive power of the FE modelling technique for the specific application of active acoustic SHM. Two Lamb wave propagation modes were identified both theoretically and experimentally: the Global Lamb Wave mode and the Leaky Lamb Wave mode. Occurrence of these modes was dependent on the central frequency of the transmitted acoustic signal and the bulk wave velocities in the sandwich structure’s core compared to the Lamb wave mode propagation velocity in the structure’s skins. Other modes (True modes and Rayleigh modes) were identified theoretically, but could not be experimentally confirmed. It was expected and shown experimentally that the presence of impact damage on the propagation path of a signal with 120kHz central frequency reduced the time travelled by this signal between two points, while increasing the amount of energy lost. The latter effect was shown to be reversed at 160kHz, which was explained by the propagation of the signal at this frequency as Leaky Lamb Wave. The FE model could predict the overall trend at 120kHz, but not the exact magnitude of the influence of impact damage on the through-transmitted signal.","Structural Health Monitoring; Lamb Waves; Sandwich Composites; Barely Visible Impact Damage; Leaky Lamb Waves; Global Lamb Waves","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","Structural Integrity & Composites","",""
"uuid:c5edb255-dacc-4985-b2cd-0bedfeec04d2","http://resolver.tudelft.nl/uuid:c5edb255-dacc-4985-b2cd-0bedfeec04d2","Motion Fidelity Assessment for Helicopter Simulations: Extending the Objective Motion Cueing Test to Measure Rotorcraft Simulator Motion Characteristics","Dalmeijer, W.H.","Mulder, M. (mentor); Pavel, M. (mentor); Voskuijl, M. (mentor); Stroosma, O. (mentor); Miletović, I (mentor)","2016","The Objective Motion Cueing Test (OMCT) refers to a way to measure motion characteristics of a simulation objectively, by constructing so-called frequency response functions of the cueing system. Research in recent years has applied the OMCT to a number of fixed-wing research simulators. However, the effect of aircraft dynamics on predicted motion fidelity of the OMCT is poorly understood. The goal of this research therefore is to increase the understanding of the OMCT, by applying it to helicopter simulations. From literature, it was found that abstractions on the input signals of the OMCT may affect the representativity of predicted motion characteristics. As a first step in this thesis, the effect of these assumptions on the predicted motion characteristics of the OMCT was studied. It was seen that the current OMCT has a set of input signals which may be representative for heave motion, but might not be representative for pitch and surge motion characteristics. Therefore it was investigated whether a potentially superior OMCT, better representing helicopter motion, can be defined. An OMCT was tailored to longitudinal helicopter motion. Notable differences in pitch and surge motion characteristics were found. However, for pilot-in-the-loop training, the aircraft motion does not only depend on the dynamics of the aircraft model, but also on pilot input. Therefore, using pilot-in-the-loop simulation data, the effect of manual pilot control behaviour on the proposed methodology was studied. It was seen that, although differences were identified, the main trend of the frequency response functions was determined by the dynamics of the helicopter model, not the pilot input. Further research is recommended to evaluate the current set of input signals of the OMCT for a variety of models, also incorporating lateral motion, and tasks using a similar method presented in this thesis.","","en","master thesis","","","","","","","","2021-12-08","Aerospace Engineering","Control and Simulation","","","",""
"uuid:f759a4e3-cb43-4922-8001-31d70c95268f","http://resolver.tudelft.nl/uuid:f759a4e3-cb43-4922-8001-31d70c95268f","A mission planning tool design for re-entry","Van Doorn, S.","Ambrosius, B.A.C. (mentor)","2010","A transition through the Earth's atmosphere is inevitable if it is desired to bring or return something useful from space. The transition is also known as the atmospheric entry, which is characterised by a highly energetic vehicle. Three types of entry can be distinguished: ballistic, glide and skip entry. In the hypersonic transition of a glide entry, the heating and structural loading can become severe enough to damage the vehicle and/or the crew. The attitude of the vehicle has to be controlled to avoid this. In addition, the vehicle should target an interface with the TAEM phase. During which the vehicle is aligned with the runway. The process of determining the attitude throughout entry is called mission planning. For on-board mission planning, simplifications need to be made on the vehicle, its environment and the flight dynamics to achieve an acceptable computation speed. As a consequence, the real trajectory will deviate from the planned trajectory. The trajectory tracker has the task to steer the vehicle towards the planned trajectory. The combination of a planning and tracking algorithm forms a guidance algorithm. The main question of this thesis work is formulated as: Is it possible to design an on-board executable guidance algorithm, for the hypersonic transition phase, which safely targets the TAEM interface? Four tasks have been derived from this question: simulator development, planning algorithm design, tracking algorithm design and guidance algorithm testing. The simulator serves as a test bed for the guidance algorithm. In the development of this software, a systems-based approach is taken with respect to the vehicle and its environment modelling. The advantage is that the software has a clear modular structure and it becomes easy to extend the simulator with new capabilities. The design of a trajectory planner has been decomposed into an angle of attack and bank angle planner. The angle of attack planner operates on the assumption of an equilibrium-glide trajectory. The bank angle planning algorithm is centered around an iterative search for a drag profile that corresponds to an estimated trajectory length travelled between entry and TAEM interface point. By incorporating the bank angle planning and tracking algorithms in one guidance algorithm, the main question is answered positively. The algorithm executes fast enough for an on-board implementation.","Mission; Re-entry","en","master thesis","","","","","","","","2010-10-20","Aerospace Engineering","Space Engineering","","Astrodynamics & Space Missions","",""
"uuid:f3b96bcb-4df3-466e-8c2e-0bd37bcd8dba","http://resolver.tudelft.nl/uuid:f3b96bcb-4df3-466e-8c2e-0bd37bcd8dba","Predicting Onset of Damage in Special Class of Laminates under Tension","Kosmas, N.","Kassapoglou, C. (mentor)","2015","In design with composite materials, the capability of tailoring the properties of the structure with respect to the specific load requirements in each direction, allowed by their anisotropic nature, is coupled with the development of interlaminar stresses transferred through the thickness. Specifically, at the free edge of the laminate, due to the change in fiber orientation and the unique response of the constituent materials, stresses are developed in the thickness direction. Moving towards the center of the laminate up to a certain threshold, the stress state of the plies is further complicated by that phenomenon. The primary goal of the thesis project was to develop an analytical stress model for both the in-plane and the out-of-plane stresses acting within the laminate. Furthermore, the model was intended to capture a specific sequence of damage occurrences in laminates of the family [02/?2/-?2]s loaded under tension, as observed by O’Brien. Namely, during loading, matrix cracks initiating at the free edge of the off-axis plies and propagating along the respective fiber orientation are anticipated to occur first. While these cracks increase in length and number, at some point a +? crack will intersect with a – ? one, forming an envelope with the free edge. Continuing, a local delamination is expected within this envelope. In order to predict that, the stress expressions would have to be implemented in a failure theory that is capable of accounting for the ongoing phenomena and of distinguishing between different matrix failure modes. These requirements led to the selection of Puck Failure Theory. The process proved to be more complex than estimated. At first, results from literature could not be duplicated. After an extensive period of thoroughly checking and editing the approach, the expressions and the code in which they were implemented, it was realized that a multiplicative factor is distorting the output. After calculating and applying the factor for each one of the out-of-plane stress expressions, agreement with published results was excellent. Unfortunately, the origin of the error could not be found. Once the error has been corrected, the potential integration of the stress expressions in a fatigue life evaluation model specifically designed for composites, could replace the currently employed semi-empirical theories that where originally formulated for isotropic materials and rely mainly on curve-fitting.","composites; interlaminar stresses; free edge effects; stress analysis; damage initiation","en","master thesis","","","","","","","","2015-01-09","Aerospace Engineering","Structural Integrity & Composites","","Design and Production of Composite Structures","",""
"uuid:56c51c8a-a2f8-41ab-9719-1c41052c8bd2","http://resolver.tudelft.nl/uuid:56c51c8a-a2f8-41ab-9719-1c41052c8bd2","Aerodynamics of a two-bladed propeller with passive blade tip-vortex control","Vedamanickam, S.","Veldhuis, L.L.M. (mentor); Ragni, D. (mentor)","2016","","","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ccb56154-0b70-4a41-8223-24b0f8d145c5","http://resolver.tudelft.nl/uuid:ccb56154-0b70-4a41-8223-24b0f8d145c5","An Investigation of the Non-Linear 3D Flow Effects Relevant for Leading Edge Inflatable Kites","Deaves, M.E.","Schmehl, R. (mentor); Gaunaa, M. (mentor); Gillebaart, T. (mentor)","2015","The kite power group at TU Delft is currently researching the use of leading edge inflatable (LEI) kites for use in power generation. A thorough understanding of the aeroelastics of these kites is paramount to the development of system simulation models and optimum kite and system designs. The current lack of understanding is therefore seen as a roadblock to the development of a commercially viable kite power system. The aeroelastics of LEI kites are complicated by three main challenges. There is a high degree of coupling between the flexible kite and the aerodynamic loading. This means that a fluid-structure interaction approach is typically needed to produce accurate simulation results. The low aspect ratio and large anhedral of the kite means that 3D effects are significant. During normal power production it is desirable to fly the kite at high angles of attack where significant non-linear viscous phenomena (e.g. flow seperation) are known to occur. In order to model correctly the 3D viscous aerodynamic phenomena present in LEI kite flight a computational approach utilizing a steady-state Reynolds-Average-Navier-Stokes (RANS) solver has been suggested. This work presents a review of relevant literature, outlines the computational approach taken, and discusses the limitations and computational costs of the approach. It was found that the RANS approach is able to model the kite’s flow environment up to angles of attack of 24?. At angles larger than this significant flow separation from the suction surface of the kite precludes the use of a steady-state solver. At angles as low as 18? significant non-linear effects begin to take effect, decreasing lift and increasing drag. It was also found that at lower angles of attack separation from behind the leading edge tube serves to decrease effective camber and therefore lift. The computational cost of the approach is heavily influenced by the quality of the mesh generated, in particular the presence of non-orthogonal cells. It is concluded that the RANS approach is capable of quantifying well the non-linear flow effects of LEI kites at moderately high angles of attack. The challenge of this method in the future will be to decrease it’s significant computational costs so that it may be used in the context of systems modeling, optimization, or fluid-structure interaction.","Windenergy; kite power; aerodynamics; wind energy; RANS; CFD","en","master thesis","","","","","","","","","Aerospace Engineering","Wind Energy","","European Wind Energy Master","",""
"uuid:e5b82e48-5954-4440-81c9-490f9999fd5b","http://resolver.tudelft.nl/uuid:e5b82e48-5954-4440-81c9-490f9999fd5b","An Investigation into the Effects of Eye Activity on Human Perceptual Remnant and Control","Popovici, A.","Mulder, M. (mentor)","2016","","manual control; perceptual remnant; eye tracker; crossover model; pupillary light reflex","en","master thesis","","","","","","","","2017-07-31","Aerospace Engineering","Control & Operations","","","",""
"uuid:ffdd3163-70da-4c20-a79c-6d955f176fb7","http://resolver.tudelft.nl/uuid:ffdd3163-70da-4c20-a79c-6d955f176fb7","Aircraft Noise Prediction: A comparison between current established methods","Haasdijk, S.M.","Snellen, M. (mentor)","2016","Noise prediction models are critical to assess the noise production of aircraft. They are of growing importance due to the increase in air transport and population. This research focusses on the comparison of the noise predictions of empirical and semi-empirical models. The noise predictions of NIROS, an empirical noise prediction model used by Deutsche Flugsicherung (the German air traffic control), are compared with the noise predictions of the DLR model PANAM. Both models are assessed on their use, applicability and limitations using a simulation case. Three major difference were found during the initial research i.e. the use of Noise-Power-Distance tables in empirical noise modelling and noise source modelling in semi-empirical noise models, the differences in noise propagation methods applied for ground reflection and atmospheric absorption and the differences in the construction of the flight path. A simulation case was constructed to further examine the differences in the noise predictions of both models. In PANAM and NIROS an A319 was used to simulate the noise for observers located on the ground. The results of the simulations showed higher noise levels in PANAM than in NIROS. Furthermore the difference in flight path and the applied ground reflection method had the biggest influence on the simulation results. Better understanding of the differences between the models can be used to make improvements to the fully empirical method.","","en","master thesis","","","","","","","","2016-11-25","Aerospace Engineering","Control & Operations","","Aircraft Noise and Climate Effects (ANCE)","",""
"uuid:b93b0689-5776-4d23-a04b-14e6704a89c8","http://resolver.tudelft.nl/uuid:b93b0689-5776-4d23-a04b-14e6704a89c8","Modelling the manufacturing and installation costs of offshore wind farm substructures for a micro siting model","Verhaegh, Max","van Bussel, G.J.W. (mentor); Zaaijer, M.B. (mentor); Voskuijl, M. (mentor); van der Male, P. (mentor); Blokland, J. (mentor)","2014","Offshore wind energy is expected to generate a large part of Europe’s sustainable electrical energy by the year 2020. In the design of an offshore wind farm a large number of components interact with each other, resulting in a certain cost of electricity. In order to reduce these costs of electricity the design of an offshore wind farm can be optimized by a micro siting model. A micro siting model uses a description of both the expenses and revenues of all offshore wind farm components in order to find the optimal offshore wind farm. It is found that current literature does not describe the estimation of substructure manufacturing- and installation cost for the purpose of a micro siting model. Therefore, the objective of this thesis is to: “ Develop a model that provides data to a micro siting model, concerning the manufacturing and installation costs of offshore wind farm substructures. The model should be able to analyze different combinations of substructure types and installation vessel types.”","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","Sustainable Energy Technology","",""
"uuid:d6a2fcf8-7fce-4eb8-857b-209b9faac755","http://resolver.tudelft.nl/uuid:d6a2fcf8-7fce-4eb8-857b-209b9faac755","Particle System Modelling and Dynamic Simulation of a Tethered Rigid Wing Kite for Power Generation","Karadayi, M.C.","Schmehl, R. (mentor); Fechner, U. (mentor)","2016","Kite Power research group at TU Delft developed the KiteSim framework for dynamic simulation of crosswind kite power systems. Currently, KiteSim has the capability to simulate leading edge inflatable kites. The use of rigid wing kites in crosswind kite power systems is becoming widespread. Accordingly, KiteSim framework is planned to be augmented to simulate the rigid wing kite power systems as well. Therefore, objective of this thesis is set to enhance the KiteSim framework in order to include the capability of the dynamic simulation of a rigid wing pumping crosswind kite power system by developing a particle system model to represent the tethered rigid wing. The particle system model of rigid wing consists of 6 point masses and 13 spring-damper elements. Positions and masses of the discrete particles are calculated in order to represent the rigid wing properties accurately. The spring-damper elements are interconnecting the particles. Lifting line theory and Kirke’s post stall correlation methods are used to create the full angle of attack aerodynamic model for wings and tails. Available atmospheric, tether and winch models of the KiteSim framework are also used for rigid wing dynamic simulations. Equation of the motion of the particle system model is formulated as an implicit problem, which is simulated by implicit Runge-Kutta method of fifth-order. Validation simulations are conducted with the particle system model of NASA SGS 1-36 flight test sailplane. Validation cases show satisfactory results with the flight test data. For the remaining simulations, AP2 PowerPlane of Ampyx Power is modelled as particle system and manually flown in KiteSim. Mass properties of the model is found to be highly accurate throughout the simulations. Power generation capabilities of the model is checked by flying figure-of-eight trajectories. Reel-out phases are investigated, a peak mechanical power of 45 kW and a mean power of 10 kW are obtained. Further comparison of the reel-out dynamic simulations with the quasi-steady theoretical calculations is done. Moreover, gliding and stalling manoeuvres are simulated for a plausibility check study. The developed particle system model for rigid wings shows satisfactory results and a potential for further development.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","Flight Performance and Propulsion","",""
"uuid:2554749a-0a73-4238-884f-89ee948b548a","http://resolver.tudelft.nl/uuid:2554749a-0a73-4238-884f-89ee948b548a","Solution to the Steady Transonic Small Disturbance Integral Equation","Cankaya, E.","Van Zuijlen, A.H. (mentor)","2016","","","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:bb173666-91f8-4e27-bb2e-2221d5f03e18","http://resolver.tudelft.nl/uuid:bb173666-91f8-4e27-bb2e-2221d5f03e18","Acoustic emission monitoring of fatigue damage progression in composite ship structures: A constitutively-informed approach to acoustic emission source classification","Groeneboom, B.","Groves, R.M. (mentor)","2016","AE-based structural integrity monitoring of composite structures potentially offers the means to gain knowledge on in-service damage accumulation, as well as mitigation of some of the risks associated with in-service damage. However, validation of any identified classes of AE events with regard to their underlying source mechanics is generally limited to data-centred metrics in existing literature. The approach in this project applies a mechanics-informed perspective on AE event classification by using the fatigue cycle phase as hit labels and validating this labelling with the stiffness degradation measured using DIC. A promising correlation is found between this labelling and the coupon stiffness degradation.","acoustic emission; structural monitoring; composites; glass-fibre composite","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:de375de9-bdb9-4e96-a6fc-23947c452d2b","http://resolver.tudelft.nl/uuid:de375de9-bdb9-4e96-a6fc-23947c452d2b","Modelling and Simulation of Decision-making Processes in Airline Operations Control","Belhadji, K.","Blom, H.A.P. (mentor)","2016","Airlines are subject to external events that may disrupt their day-to-day operations. These disruptions lead to additional costs for crew, fuel, aircraft, maintenance and a loss of passenger goodwill. Therefore, each airline has an Airline Operations Control (AOC) department that is responsible for disruption management. The problems faced by AOC can be highly complex and decisions have to be made under severe time constraints, economic pressure and various uncertainties. In addition, slacks in the schedule and availability of standby resources affect disruption management. To address this research question, a simulation model is developed which reflects the ontology of an AOC and its environment. Scenarios that have designed by industry experts are selected from the literature that represents a real-world disruption. Subsequently, a vast amount of qualitative data has been gathered that describe the socio-technical system in terms of uncertainties the controllers face, the tasks they perform and their interactions. By structuring the interactions and by conceptualizing the uncertainties into conditions and parameters, a model is designed that expresses both quantitative and qualitative aspects of AOC and it operating environment. The model is implemented into an order-sorted predicate logic software environment that is able to describe temporal properties. Model evaluation is done using a case by case approach in which for each case, condition sequences and parameters are selected. By conducting sensitivity analysis, the impact of the size of slacks, availability of standby resources and uncertainties on direct costs, utilization of reserve resources and passenger goodwill is determined. Subsequently, the implications of these factors on the decision-making process are analysed. For instance, evaluation of the results show that a lack of information to overcome an uncertainty could result in extra (unnecessary) tasks to be performed by other controllers in the decision-making process and it could result in deployment of costly recovery strategies.","airlines; airline operations control; decision-making processes","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Transport & Operations","","","",""
"uuid:e4297489-60e2-403e-a246-1b1ea4c4ea63","http://resolver.tudelft.nl/uuid:e4297489-60e2-403e-a246-1b1ea4c4ea63","High-Order Numerical Schemes for Compressible Flows","Satheesh Kumar Nair, V.","Dwight, R.P. (mentor)","2016","High-order numerical methods for Computational Fluid Dynamics have undergone significant fundamental developments over the last two decades owing to combined efforts from the applied mathematics and engineering communities. Even though low-order numerical methods are still the standard in industry, the increased requirements of engineering applications have led to significant scientific interest in developing efficient and robust numerical methods. Applications that would benefit from high-order numerical methods include Direct Numerical Simulations (DNS), Large Eddy simulations (LES), Computational Aero-Acoustics (CAA) and vortex dominated flows. The objective of this thesis is to successfully implement and validate a fifth order traditional WENO scheme in a finite volume framework, for a solver currently being developed in the Aerodynamics group of TU Delft. A detailed literature study of classical numerical schemes has been performed along with a study of the traditional WENO schemes. The quality of results using the fifth order scheme is studied for a variety of test cases to study the shock capturing ability of the scheme. Implementing the finite volume WENO schemes includes the calculation of numerical flux at cell faces using Gaussian quadrature formulas. The effect of varying the number of Gaussian quadrature points while calculating the numerical flux is investigated. Also, the effect of the approximate Riemann solvers on the quality of results is studied by implementing four different Riemann solvers and studying the results for different test cases using these Riemann solvers. The test cases are governed by the inviscid Euler equations and deals with flow in the compressible regime. They involve shocks, other discontinuities and often also complicated structures in the smooth part of the solution which tests the design of the schemes to be non-oscillatory at the discontinuities and still gives a high order of accuracy in the smooth parts of the flow. Convergence tests of the error for test cases using the linear advection equation is used to study the order of accuracy of the scheme using different number of Gaussian quadrature points. The tests clearly show that the order of accuracy remains the same irrespective of the number of quadrature points used. This result is important as it allows simulation run with just one quadrature point which is less expensive, and saves memory. This result is highly relevant while running test cases for LES where very fine grids have to be used. WENO schemes have been considered to be too dissipative for LES in their traditional form. This is indeed true as seen by Kelvin-Helmholtz type small scale vortices (which are characteristic of high Reynolds number flows), even in the test cases using the inviscid Euler equations, due to the inherent dissipation in the schemes. However, this could be seen as motivation for using the WENO schemes for Implicit LES where no explicit sub-grid scale models are used to represent the unresolved scales. The different Riemann solvers exhibit different levels of dissipation and recommendations are made for the choice of Riemann solvers according to the application.","CFD; numerical schemes; WENO; Riemann solver; Finite Volume","en","master thesis","","","","","","","","","Aerospace Engineering","Flight Performance and Propulsion","","","",""
"uuid:160dbf23-207f-4178-b67b-4f5115d8a26b","http://resolver.tudelft.nl/uuid:160dbf23-207f-4178-b67b-4f5115d8a26b","Air-Wake Flow Dynamics on a Simplified Frigate Shape: An Experimental Study by Large-Scale Tomographic PTV","Rius Vidales, A.F.","Sciacchitano, A. (mentor)","2016",": The Air-Wake produced by a ship superstructure is a complex, highly turbulent and unsteady three-dimensional flow, which contains large flow features that interact with the helicopter rotor during critical take-off and landing procedures. An international research effort (TTCP, AER-TP2) which involves experimental and numerical studies on simplified frigate shapes SFS has been conducted with the aim of understanding and simulating the ship air-wake. An unexpected asymmetry of the time-averaged air-wake flow has been noted when the model is oriented parallel to the free-stream direction. In this condition, it has been suggested that the flow features a bi-stable behavior which requires further investigation. During this research project the air-wake flow dynamics on the landing deck of a simplified frigate shape (SFSN) modified by the Netherlands Aerospace Laboratory has been studied using time-resolved large-scale Tomographic Particle Tracking Velocimetry with helium filled soap bubbles. The results show that the time-average flow-field at head-wind condition (ß=0º) on the SFSN present a slight asymmetrical stream-wise velocity distribution, where higher velocity deficits are located on the starboard-side of the model. The time-averaged air-wake structure suggests that the horse-shoe vortex structure from the funnel super-structure convects downstream and interacts with the flow-field on the landing deck. Moreover, the analysis revealed that, as expected, an arch vortex is present in the proximity of the step wall. A low order reconstruction led to an unambiguous identification of the recirculation region on the instantaneous measurements, where the velocity difference between both sides of the deck is calculated. Based on this difference, three flow-states (PS port-side, SB Starboard side and SY symmetric) have been identified. An alternation factor was calculated to determine the number of occurrences of each flow state and the consecutive time that the flow remained on a specific state. This result suggests that at head-wind condition the flow is stable for either (PS, SB) and unstable for (SY) which is considered to be a transitional state. This shows that the air-wake flow of the SFSN at headwind condition is bi-stable and that the bi-stability is restricted to the range ß=+/- 1º degree of yaw. The results from the probability based on the number of occurrence of each flow state show that at head-wind condition the flow state SB presents a higher probability than the flow state PS, which explains the slight asymmetry observed on the stream-wise time-averaged velocity distribution. Finally, the experimental results obtained during this research project contribute to the area of knowledge by characterizing, in spatial and time domains, this complicated bi-stable flow using a three-dimensional flow measurement technique. Moreover, the experimental campaign performed at the Low Speed Wind Tunnel of the German-Dutch Wind Tunnels show that it is possible to perform large-scale flow measurements using time-resolved Tomographic Particle Tracking Velocimetry with HFSB in an industrial wind tunnel facility. This opens new possibilities to the study of aerodynamic industrial applications and more specifically three-dimensional bi-stable bluff-body air-wakes.","Wind Tunnel Testing; Tomographic PTV; Bluff-body; Bi-stability; Simplified Frigate Shapes; Ship Air-Wakes; Aerodynamics","en","master thesis","","","","","","","","","Aerospace Engineering","Department of Aerodynamics","","","",""
"uuid:4ea07ffc-6749-4ceb-95b8-448f779d87d5","http://resolver.tudelft.nl/uuid:4ea07ffc-6749-4ceb-95b8-448f779d87d5","Fault Detection and Isolation for Linear Dynamical Systems","Monteiro, D.","Oliveira, P. (mentor); Rosa, P. (mentor); Silvestre, C. (mentor)","2015","Safety and reliability of a dynamical system is a concern that have always pursued designers in both academia and industry. Monitoring the health status of a system is even more relevant for safety critical applications, such as chemical and nuclear plants, medicine, transportation, and security systems. The occurrence of abnormal events on these processes may lead to malfunctions and disasters in ultimate fault conditions, as witnessed in the past. The paramount importance of the topic and the increasing interest in multiple-model approaches under the scope of on-line fault detection and isolation motivates this thesis. Initially, focus is given to classical multiple-model adaptive estimation (MMAE) in which an in-depth study is undertaken for the design of a scheme capable of determining the working regime of a system. This is done by identifying the region where the fault parameters lie under the associated uncertainty domain. The design procedure is built on a performance-based strategy, which ensures a well-defined level of state estimation performance despite the fault location. Due to the high computational complexity of the classical MMAE approach, in what follows we propose a novel bank design based on the combination of Kalman and robust H2 filters. This strategy leads to a substantial reduction on the number of estimators in the bank, while preserving the desired state estimation performance. In both approaches a prominent study on convergence properties is performed, so that robustness of the methods is guaranteed. Computational simulations based on a generic helicopter model are also executed to prove the potential of the strategies developed and provide a verification basis for the theoretical results achieved.","multiple-model adaptive estimation; model-based fault diagnosis; robust H2 filters; state estimation in uncertain systems","en","master thesis","","","","","","","","","Aerospace Engineering","Control and Operations","","Control and Simulation","",""
"uuid:9d609886-372d-466d-9cca-7e7b26b26a7f","http://resolver.tudelft.nl/uuid:9d609886-372d-466d-9cca-7e7b26b26a7f","Impact of Satellite Fragmentations in GEO Graveyard Orbits","Roelen, L.","Noomen, R. (mentor)","2016","","","en","master thesis","","","","","","","","2017-08-26","Aerospace Engineering","Space Engineering","","","",""
"uuid:fa96b280-af15-4520-b528-f93b07752e8d","http://resolver.tudelft.nl/uuid:fa96b280-af15-4520-b528-f93b07752e8d","Global Launcher Trajectory Optimization for Lunar Base Settlement","Pagano, A.","Ambrosius, B.A.C. (mentor)","2010","In the past few years, a new spirit for the exploration of the Solar System spread among the space community and reaching the Moon has been set as the first step of this new program. In this frame, going back to the Moon is needed to familiarize with a new way of living in a different environment, adapting to it and testing new technology. It is also true that, at the rate we are consuming the terrestrial resources, we will soon run out of them. This will put us in front of a dramatic change in our life style. Moreover, it is not unlikely that an asteroid could impact the Earth, causing extinction of many species and difficulties for survival. Then, these unpredictable reasons increase the importance of exploring and adapting to new extraterrestrial environments. Therefore, a feasibility study of a mission to the Moon to set up a permanent base has been carried on. The first part is concerning the delivery of the lunar payload into a LEO parking orbit. For this, the analysis of the capabilities of existing launchers is performed. The ascent trajectory problem is tackled by formulating it as an initial value problem (IVP), in which, given the launcher’s initial conditions, the state vector is propagated following a control law optimized to give the largest payload mass. Moreover, the launcher is subject to constraints dictated by the mechanical and thermal properties of the launcher itself. The optimal control law is sought by means of a Particle Swam Optimization method, which simulates the behavior of a flock of birds searching for food. Single and multi-objective optimization is performed. Single-objective optimization aims at maximizing the payload mass satisfying path constraints and the boundary constraints dictated by the orbital elements of the final orbit. Multi-objective optimization aims at maximizing the payload mass and minimizing the error on the final orbit simultaneously. Other experiments include the optimization of the two aforementioned objectives and the minimization of the violations of the path constraints. It has been found that, to fulfill the requirements of the lunar campaign, a very tight schedule and international cooperation is needed. Yet, existing launchers can be used for this mission for cargo expeditions. However, it is strongly suggested to commence development of a manned launcher and a spacecraft capable to land and host astronauts for multiple days on the Moon.","Moon; Solar system; Trajectory","en","master thesis","","","","","","","","2010-06-02","Aerospace Engineering","Space Engineering","","Astrodynamics & Space Missions","",""
"uuid:8d44eef0-1da0-47fa-b44e-cad4ab3e6a46","http://resolver.tudelft.nl/uuid:8d44eef0-1da0-47fa-b44e-cad4ab3e6a46","Optimization of interplanetary trajectories with deep space maneuvers - Model development and application to a Uranus orbiter mission","Molenaar, S.","Noomen, R. (mentor)","2009","","Deep Space Maneuvers; Orbital Mechanics; Genetic Algorithm Optimization","en","master thesis","","","","","","","","","Aerospace Engineering","Astrodynamics and Satellite Systems","","","",""
"uuid:ffa1ec41-3930-4dfe-b454-e11c3517a7f4","http://resolver.tudelft.nl/uuid:ffa1ec41-3930-4dfe-b454-e11c3517a7f4","Vertical Landing for Micro Air Vehicles using Event-Based Optical Flow","Pijnacker Hordijk, B.J.","de Croon, G.C.H.E. (mentor)","2016","Small flying robots can perform landing maneuvers using bio-inspired optical flow by maintaining a constant divergence. However, optical flow is typically estimated from frame sequences recorded by standard miniature cameras. This requires processing full images on-board, limiting the update rate of divergence measurements, thus the speed of the control loop and the robot. Event-based cameras overcome these limitations by only measuring pixel-level brightness changes at microsecond temporal accuracy, hence providing an efficient mechanism for optical flow estimation. This thesis presents, to the best of our knowledge, the first research integrating event-based optical flow estimation into the control loop of a flying robot. We extend an existing 'local plane fitting' algorithm to obtain an improved and more computationally efficient optical flow estimation method, valid for a wide range of optical flow velocities. This method is validated for real event sequences. In addition, a method for estimating the divergence from event-based optical flow is introduced, which accounts for the aperture problem. The developed algorithms are implemented in a constant divergence landing controller on-board of a quadrotor. Flight tests demonstrate that, using event-based optical flow, accurate divergence estimates can be obtained over a wide range of speeds. This enables the quadrotor to perform very fast landing maneuvers.","","en","master thesis","","","","","","","","2017-12-16","Aerospace Engineering","Control & Operations","","Control & Simulation","",""
"uuid:bb871e9d-2596-49a4-9bf2-cbed4c6a9446","http://resolver.tudelft.nl/uuid:bb871e9d-2596-49a4-9bf2-cbed4c6a9446","Investigating the drag sensitivity parameters and lateral dynamic response of a road vehicle in cross-wind flow","Fokker, A.D.","Van Zuijlen, A.H. (mentor); Veldhuis, L.L.M. (mentor)","2015","Recent trends in the automobile industry focus towards enhancing the operating efficiency of the road vehicle. One can achieve this by a combination of increasing the powertrain efficiency, reducing the weight and increasing the aerodynamic performance. The scope of this study is on the latter, i. e. enhancing the aerodynamic performance. Most cars are optimized for minimum drag in idealized conditions, driving engineers to design for the test rather than for to optimize for actual flow encountered in real world conditions. These realistic conditions include (un)steady cross-wind flows encountered by the vehicle, rather than a perfectly aligned flow as is the case in an idealized situation. Different researchers studied the effect of these real world conditions on the performance of a vehicle. Many of these studies focussed upon the vehicle stability rather than the potential to reduce aerodynamic drag. This is because typical drag reducing means (such as radiused edges) tend to have a detrimental effect on the cross-wind stability and comfort of the vehicle. \\ The introduction of the fully electric Tesla Model S created new opportunities within this conception. This 2500 {kg vehicle has an 800 {kg battery underneath the car, which results in a different - relatively flexible - position of the center of gravity, total mass and corresponding mass moments of inertia. As a result it is questioned if this difference in vehicle specifications allow for drag reducing shape modifications on a vehicle which is then still stable during cross-wind flows. After a careful trade-off it was chosen to use the recently launched open-source CFD software suite SU2 in order to find an answer to the following research objective: What design modifications reduce the drag coefficient of a simplified vehicle model which experiences a cross-wind flow, and how does this affect the lateral dynamic performance? An interesting follow-up question on this would be to identify which design variables are (most) sensitive to drag increments in realistic crosswind flows. This document describes the process of solving the research objective within the framework of a Master of Science thesis. A thorough vehicle dynamics study was performed in order to assess the most influential parameters which affect the lateral deviation of a vehicle. Within this study it was found that the cross-wind induced lateral deviation with a longitudinal velocity of 30m/s and a cross-wind flow of 3.15m/s or 6 degrees is roughly similar to the situation where the steering wheel angle is set to 1 degree. This implies that the lateral deviation during cross-wind flows is not much of an issue during steady cross-wind flows of up to 6 degrees. Experiments were designed for three different cross-wind flows; 0 degrees, 3 degrees and 6 degrees cross-wind flow for both conventional and electric vehicles. Here the effects of the following shape modifications have been studied: arrowing the front of the vehicle, tapering the aft of the vehicle, applying a side-window tumblehome angle, varying the front and rear window angle, and varying the A - and C - pillars. The resulting drag coefficients for each configuration has been averaged over the three cross-wind angles. Here it was found that the most important shape modifications for the drag coefficient occur aft of the vehicle. The optimal angles are listed below, where the original angle is shown in parentheses. The resulting cross-wind flow averaged drag coefficient is shown per shape modification. Arrowing angle (0) - 15 degrees: 5% Tapering angle (0) - 15 degrees: 27% Tumblehome angle (0) - 15 degrees: 10% Front window angle (30) - 25 degrees: 2% Rear window angle: (25) - 15 degrees: 16% A-pillar radius: (0.10) - 0.15m: 4% C-pillar radius: (0.15) - 0.15m: 0% When these design modifications are simultaneously applied it was found that the drag coefficient is reduced by 17% for symmetric flow conditions, 30% during 3 degrees cross-wind flow and as much as 43% during 6 degrees during cross-wind flow conditions. This combines into a cross-wind averaged drag reduction of 30%.","vehicle aerodynamics drag reduction vehicle dynamics","en","master thesis","","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy, Flight Performance and Propulsion","","Flight Performance and Propulsion","",""
"uuid:ec380d2d-bdf0-4f1a-9149-b989a324f021","http://resolver.tudelft.nl/uuid:ec380d2d-bdf0-4f1a-9149-b989a324f021","The near wake structure of a vertical axis wind turbine: Including the Development of a 3D Unsteady Free-Wake Panel Method for VAWTs","Dixon, K.R.","Simao Ferreira, C.J. (mentor); van Bussel, G.J.W. (mentor); van Kuik, G.A.M. (mentor); van Zuijlen, A.H. (mentor); Ramaekers, L. (mentor)","2008","A 3D unsteady multi-body panel method is developed that can model arbitrary geometries. The method has been specifically designed so that it can handle the blade-wake interactions and viscous wake effects that are important for modelling a vertical axis wind turbine (VAWT). A systematic validation and verification of the model is presented against theoretical and experimental results. Validation of VAWT wake shapes is given in 2D and 3D by comparison with experimental results using several different techniques (smoke-trail, PIV, and water-tank dye injection). A generalized wake structure for a straight bladed VAWT is explained, and how this structure deforms in time and changes with tip speed ratio and height-diameter ratio. General conclusions of this work are offered in addition to suggested topics for future research.","Windenergy","en","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d8b5b782-b329-464d-9210-89bb30494167","http://resolver.tudelft.nl/uuid:d8b5b782-b329-464d-9210-89bb30494167","Crack propagation analysis using Phase-Field model in the framework of Isogeometric analysis and Finite Cell Method","Pundir, M.","Turteltaub, S.R. (mentor)","2016","Fracture mechanics based computational methods are becoming increasingly important to study the structural integrity and failure of materials and structures used in engineering applications. One challenging aspect for computational methods is the analysis of crack nucleation and propagation in complex geometries or in materials with inhomogeneities at microstructural level as found in composite materials. To address this challenge, the present work combines three key ingredients namely, (i) the Finite Cell Method (FCM), (ii) Isogeometric Analysis (IgA) and (iii) Phase-Field model. The Finite Cell Method (FCM) has emerged as a promising computational method in order to simplify the modelling of complex geometries. FCM combined with a higher-order finite element method such as IgA has been implemented in numerous field of structural analysis. Within this context, the IgA-FCM framework isi extended to fracture mechanics through incorporation of a Phase-Field model. Phase-Field model, based on variational formulation of a brittle fracture, is used to study the nucleation and the propagation of cracks around voids and inclusions under quasi-static conditions. The ability of Phase-Field model to reconstruct fracture mechanics problems as coupled partial differential equations makes it easy to implement in the IgA-FCM framework. Due to the computationally demanding nature of the Phase-Field model, hierarchical sub-division of Non-Uniform Rational B-spline (NURBs) basis functions is implemented to achieve local refinement in IgA framework. A novel algorithm to implement hierarchical refinement in IgA-FCM framework is presented which is capable of simultaneously implementing element-based local refinement for stable crack propagation as well as Gauss Quadrature based local refinement for better integration around voids and material interfaces. For establishing the feasibility of IgA-FCM in Phase-field modelling, numerous numerical simulations such as crack nucleation around voids, inclusions and crack propagation in presence of voids, soft and hard inclusions were performed for two-dimensional cases. For relatively simple numerical cases considered in this project, modelling of voids and inclusions as fictitious domain resulted in expected crack behaviour such as crack nucleation at high stress location, curvilinear crack influenced by varying stress state in presence of inclusions. With these numerical simulations, it is shown that the IgA-FCM-Phase-Field framework can be effectively applied for fracture mechanics problems involving complex features.","fracture mechanics; isogeometric analysis; phase-field model; finite-cell method; finite element analysis; voids; inclusions; crack","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:c1d9482c-dbff-4c86-8c84-ab18e0099089","http://resolver.tudelft.nl/uuid:c1d9482c-dbff-4c86-8c84-ab18e0099089","Numerical Analysis of Horizontal Axis wind turbine with gurney flap using OpenFOAM","Ramanujam Ramdoss, V.D.","Simao Ferreira, C.J. (mentor)","2017","","Windenergy","en","master thesis","","","","","","","","2018-03-29","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:41073378-1b72-488e-9565-7177e263840b","http://resolver.tudelft.nl/uuid:41073378-1b72-488e-9565-7177e263840b","Numerical investigation of the Hypersonic Test Facility Delft (HTFD)","Shukla, R.H.","Scarano, F. (mentor); van Zuijlen, A.H. (mentor)","2010","The high speed flows with mach number above 5 are generally categorised as hypersonic flows. In order to generate hypersonic flows in wind tunnel for aerothermodynamic testing, a shock tube type setting is generally known as one of the most commonly used methods. Similarly Hypersonic test facility at TUDelft (HTFD) is a Ludwieg tube type wind tunnel which is made of a storage tube connected to the test section through a converging diverging nozzle which expands the high pressure and temperature gas in storage tube to achieve high speed flows in test section. The tunnel is started by a fast opening piston-valve which creates a strong shock progressing in to the nozzle while an expansion wave progresses in to the storage tube. The appeal of this kind of facility to the hypersonic flow regime lies in the relatively long run times (0.1 to 0.2 seconds), large test section (30 cm) and high Reynolds numbers (order of 5 – 50e+06 m-1).But there are also some technological limitations to such facilities like supply of high temperatures and pressures for times long enough to perform a measurement, fast instrumentation and power requirements to run the tunnel, just to name a few.","","","master thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:cee4dcf5-e2a8-49d0-b731-92db25b44a17","http://resolver.tudelft.nl/uuid:cee4dcf5-e2a8-49d0-b731-92db25b44a17","Kitesailing: Improving system performance and safety","van den Heuvel, J.","Ockels, W.J. (mentor); Schmehl, R. (mentor); Breukels, J. (mentor); Smit, P.D.C. (mentor)","2010","In the world of high performance sailing people are using state of the art technology to push the limits in speed and performance. The introduction of the sport kitesurfing has shown the power that kites can generate. It has meant a revolution in the world of surfing. Kitesurfing only exists since 15 years and began to expand around the world only since the year 2000. Already in 2008 the 50 knots speed sailing barrier has been broken by a kite surfer being the first sailing system to do so. This is less than ten years after the sport started to become public in the world. This illustrates the potential in performance for the use of kites.Kites also offer the possibility of a revolution in other fields like sailing where systems are currently developed to provide propulsion for commercial vessels to save fossil fuels. Kite systems are also developed for clean energy production where wind energy at high altitude is harvested. These High Altitude Wind Power systems can also be applied to ships offering the possibility of sailing at a course of 0 degrees into the wind on pure wind energy. In this research the kite system is evolved such that the performance and safety is increased for kitesailing and energy production.","maneuvers; kites; sailing; sail area; performance; speed","en","master thesis","","","","","","","","","Aerospace Engineering","Aerospace for Sustainable Engineering and Technology","","","",""
"uuid:4eb36179-9441-4c20-86ca-9cb671047da4","http://resolver.tudelft.nl/uuid:4eb36179-9441-4c20-86ca-9cb671047da4","Aerodynamic Design and Optimization of a Long Range Mini-UAV","Trips, Dennis","van Tooren, M. (mentor); Straathof, M.H. (mentor); Remes, B.D.W. (mentor); Timmer, W.A. (mentor)","2010","This thesis focuses on the development of an aerodynamic optimization algorithm for long range mini-UAV’s. This algorithm is applied to the design of the TU Delft mini- UAV that participated in the EMAV2009 outdoor endurance mission. The analysis of the low Reynolds number (< 2.5 · 105) aerodynamics on the wing is performed using a quasi-3D method which combines a vortex lattice method with viscous airfoil data. The optimization part of the program is accomplished by a sequential quadratic programming algorithm. RANS-CFD calculations and wind tunnel experiments were performed to validate the newly developed quasi-3D method. The final design for the mini-UAV has lift over drag ratio of 11.8 and a high capacity battery (8Ah) which give it a total range of 166 km","","en","master thesis","","","","","","","","","Aerospace Engineering","Department Of System Engineering and Aircraft Design","","Aerospace Engineering","",""
"uuid:1ad96acb-0e49-4edd-b453-6523e7296c50","http://resolver.tudelft.nl/uuid:1ad96acb-0e49-4edd-b453-6523e7296c50","Delfly Freeflight: Autonomous flight of the Delfly in the wind tunnel using low-cost sensors","Koopmans, J.A.","Mulder, J.A. (mentor); Chu, P. (mentor); van Kampen, E. (mentor); van Oudheusden, B.W. (mentor); Remes, B. (mentor)","2012","The Delfly is subject of great interest from the aerodynamics department at the TU Delft. Current wind tunnel measurements are performed with a dual high speed camera setup that detect particles injected in the wind stream. The difference between two subsequent images provides information on the flow field around the wings of the Delfly. These measurements are always performed with the Delfly fixed on a support. Although this method produces a lot of useful data, the restrictions that the support introduces makes it not a true representation of the free flight conditions. This thesis goal therefore, was to design, build and test a system that would enable the Delfly to fly freely in the wind tunnel. This would allow the same measurements to be performed without a support, providing insight in the influence of the support on the aerodynamic properties of the Delfly. A low-cost, high performance tracking system using two Wiimotes was developed, providing 3D position information with an accuracy of 0.8 mm and a tracking rate up to 80 Hz. A custom auto pilot module was designed, containing a 3-axis gyro and an infrared camera. A small Bluetooth module provided two way communication between the Delfly and the ground station, allowing the position information to be sent up to the Delfly and can log the information from the on-board sensors. Using the tracking system and a LED in the middle of the wind tunnel to provide the camera with a heading reference, a PI controller was implemented on-board. The controller could successfully keep the Delfly within ±1.7 cm in forward and vertical direction, and within ±3.5 cm in lateral direction of the reference point. It is the first time in the world that a flapping wing micro aerial vehicle was flown autonomously in the wind tunnel. The achieved precision is sufficient for the aerodynamic measurements to be performed, which could shed more light on the way the wind tunnel support influences the properties of the Delfly. Furthermore, for the first time, good quality data has been gathered on the dynamic behavior of the Delfly. This can serve as a starting point for future projects, such as the design of more advanced controllers that cope with the observed non-linearities or provide a reference for future research on the dynamics of the Delfly","","en","master thesis","","","","","","","","","Aerospace Engineering","Department of Control and Simulation","","Aerospace Engineering","",""
"uuid:03f73d85-3684-499c-affc-637d2a5971bf","http://resolver.tudelft.nl/uuid:03f73d85-3684-499c-affc-637d2a5971bf","Improving flight performance of DelFly II in hover by improving wing design and driving mechanism","Bruggeman, Bart","van Tooren, M.J.L. (mentor); Bijl, H. (mentor); Ruijsink, H.M. (mentor); Remes, B.D.W. (mentor); Goosen, J.F.L. (mentor)","2010","Recent years have seen an increasing interest in micro aerial vehicles (MAV). The same can be said about flapping flight. The Delft University of Technology started to develop a flapping wing MAV in 2005, ”DelFly”, which relies on a flapping biplane wing configura- tion for thrust and lift generation. DelFly has evolved significantly during the last years. At the time of writing there are already three version of DelFly; DelFly I, DelFly II and DelFly Micro. The test subject of this study is DelFly II because of its stable and broad flight envelope. The aim of this study is to improve flight performance of the DelFly II. Hereto, in this thesis report, a wing geometry study is performed in order to improve the aerodynamic performance of the wing and the driving mechanism is improved in order to increase the efficiency of energy transfer from the battery to the movement of the leading edges. The current study resulted in a increase of thrust-to-power ratio of 5% due to the wing design and 20% due to the new crank-shaft mechanism","","en","master thesis","","","","","","","","","Aerospace Engineering","Department of System Engineering and Aircraft Design","","Aerospace Engineering","",""
"uuid:8ff1faa1-ccf4-45d7-969e-e0881c7d8342","http://resolver.tudelft.nl/uuid:8ff1faa1-ccf4-45d7-969e-e0881c7d8342","Helicopter","Van Holten, T.","","2004","The invention relates to a helicopter provided with a rotor with at least one rotor blade (5), wherein drive means are provided for actively moving the or each rotor blade up and down during rotation of the rotor, in particular about a flapping hinge (8) thereof, so that moments, applied by the rotor to the fuselage (1) are prevented.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2ccb99c0-45d9-4a97-ac91-afa921bd21dc","http://resolver.tudelft.nl/uuid:2ccb99c0-45d9-4a97-ac91-afa921bd21dc","Motion simulator with exchangeable unit","Mulder, J.A.; Beukers, A.; Baarspul, M.; Van Tooren, M.J.; De Winter, S.E.E.","","2001","A motion simulator provided with a movable housing, preferably carried by a number of length-adjustable legs, in which housing projection means are arranged for visual information supply, while in the housing a control environment of a motion apparatus to be simulated is situated, the control environment being incorporated in a removable unit, which unit is exchangeable for another, comparable unit having a different control environment to be simulated","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5973a154-4f07-4744-91dd-ebfb063e71d0","http://resolver.tudelft.nl/uuid:5973a154-4f07-4744-91dd-ebfb063e71d0","Side skirt for a pulled vehicle","Van Raemdonck, G.M.R.","","2009","The present invention relates to a device for minimizing the aerodynamic drag that results when tractors, trailers, rigid trucks, lorries, and other vehicles are moving through air. In particular the invention relates to a plate-shaped flow conductor (31) having a front edge, a lower edge, a rear edge and an upper edge. The flow conductor is mountable along the upper edge (34) in a substantially vertical position to a body portion of a pulled vehicle of a vehicle combination of at least two pivotally connected vehicles. When mounted the flow conductor extends at least partially under the body portion in a longitudinal- direction of the1 pulled vehicle. Characteristic for the flow conductor according to the invention is that the flow conductor comprises locally in conjunction with the front edge a thickened portion (78,85), which has a streamlined outer contour (83,84) in a cross section transversally to the front edge.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Aerospace Structures & Design Methodology","","","",""
"uuid:96f4dbb6-670b-4778-ae1d-864c3f9fcec9","http://resolver.tudelft.nl/uuid:96f4dbb6-670b-4778-ae1d-864c3f9fcec9","Method of manufacturing a motion simulator, and a motion simulator","Beukers, A.; Van Baten, T.; Advani, S.K.","","1996","A method of manufacturing a motion simulator, which motion simulator has a deck and a number of deck-supporting legs (2) that are pivotally connected with the deck in first pivot points (4), the legs being actively and continuously length-adjustable, such that the deck is capable of describing a motion envelope comprising all desired deck positions, wherein a leg envelope is determined for each leg within which the possible positions of the relevant leg are located, whereafter the common surrounding space of the legs, and in particular the interspace included between the leg envelopes, is determined, whereafter a shell (1) is then designed that at least carries the deck, which shell defines an inner space extending at least partly within the interspace between the legs (2) defined by the leg envelopes, in such a manner that in each position of the simulator,; the legs are clear of the shell (1).","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:916f0a23-4d49-494a-8d37-73cacb5efb16","http://resolver.tudelft.nl/uuid:916f0a23-4d49-494a-8d37-73cacb5efb16","Kite, method of generating power using such a kite, method of providing driving force to a vehicle using such a kite, vehicle provided with such a kite, power generation assembly comprising such a kite","Ockels, W.J.; Ruiterkamp, R.; Lansdorp, B.","","2008","A kite having a main body provided with at least a first and a second connection cable and at least one main pulling cable, the at least first and second connection cables each having a first and a second end, the first ends of the at least first and second connection cables being connected to the main body of the kite at different positions of the main body, the second ends of the at least first and second connection cables being connected to the main pulling cable, wherein at least one regulator is provided between the first ends of the connection cables and the main body and/or between the second ends of the connection cables and the at least one main pulling cable, a control being provided for controlling the at least one regulator so that the kite is steereable.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:476a365c-6437-449a-a7fd-31c99a513f48","http://resolver.tudelft.nl/uuid:476a365c-6437-449a-a7fd-31c99a513f48","Method of making a foamable film","Kluit, P.W.; Beukers, A.","","1996","The present invention is directed to a method of making a foamable film of at least one thermoplastic resin with at least one liquid blowing agent incorporated therein, said method comprising forming the thermoplastic resin and a liquid swelling agent for the thermoplastic resin into a layer, contacting the said layer with the liquid blowing agent and replacing at least part of the swelling agent in the resin by the liquid blowing agent.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a98863a2-a882-415f-bd31-17c97736cec6","http://resolver.tudelft.nl/uuid:a98863a2-a882-415f-bd31-17c97736cec6","Projection and registration device","Verlinden, J.C.","","2009","A projection and recording device, provided with a processing and control unit, a memory for recording images and other data, an input/output interface, a controllable camera, a touch screen for the input and display of data and images, a position determining system for determining the position of at least one object in relation to the projection and recording device, with images recorded by the camera being storable in the memory and displayable on the touch screen, and a projector for projecting an image stored in the memory onto the at least one object, whereby the cooperation between the position determining system and the projector enables the projector to project images onto the object.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Design Engineering","","","",""
"uuid:460a18a3-764d-4c91-a65a-f63775721b0b","http://resolver.tudelft.nl/uuid:460a18a3-764d-4c91-a65a-f63775721b0b","Method for bonding a thermoplastic polymer to a thermosetting polymer component","Van Tooren, M.J.L.","","2012","The invention relates to a method for bonding a thermoplastic polymer to a thermosetting polymer component, the thermoplastic polymer having a melting temperature that exceeds the curing temperature of the thermosetting polymer. The method comprises the steps of providing a cured thermosetting polymer component comprising an implant of a thermoplastic polymer at least at the part of the thermosetting polymer component to be bonded, locating a thermoplastic polymer in contact with at least the part to be bonded, heating the assembly to the melting temperature of the thermoplastic polymer, whereby the thermoplastic polymer of the implant melts and fuses with the thermoplastic polymer, and cooling the assembly. The thermoplastic polymer has a melting temperature that exceeds the curing temperature of the thermosetting polymer, and the implant is designed such that heating above the maximum operating temperature of the thermosetting polymer at the interface of the implant with the thermosetting polymer component is avoided during the bonding step.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:3da4670d-1d2f-466c-b0d9-f31e86cb81e1","http://resolver.tudelft.nl/uuid:3da4670d-1d2f-466c-b0d9-f31e86cb81e1","Vaartuig voor het overzetten van personen of goederen op een offshoreconstructie","Van der Tempel, J.; Molenaar, D.P.; Mulder, H.; Cerda-Salzmann, D.; Hoonings, S.","","2006","The vessel (3) is for the transfer of persons or goods to an offshore construction (1,2) and has an upper deck (4) with a platform (5) regulatable as to its position. The platform is supported on hydraulically regulated cylinders (6) fitted on the upper deck. Movement sensors (7) are employed to measure the vessel movements and to them is connected a regulating system coupled to the hydraulic regulating systems. This system, dependent upon the vessel movements, adjusts the position of the platform. -","","nl","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4d0cf57a-701d-446e-acb5-c63b56c054e0","http://resolver.tudelft.nl/uuid:4d0cf57a-701d-446e-acb5-c63b56c054e0","Motion simulator with movable base plate","Advani, S.K.","","1999","A motion simulator comprises a deck supported by a number of length-adjustable legs. The legs are connected to a baseplate which is, in turn, supported by a number of swivel arms which support the baseplate relative to a ground plate. The configuration of legs and swivel arms allows the deck five degree of freedom relative to the baseplate.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9c5e4c30-8ceb-4127-a9ac-4648a32b4789","http://resolver.tudelft.nl/uuid:9c5e4c30-8ceb-4127-a9ac-4648a32b4789","Pressurizable structures comprising different surface sections","Koussios, S.; Bergsma, O.K.; Beukers, A.","","2004","The invention relates to composite pressurizable structures which are overwound with fibres or are braided. The pressurizable structures comprise axial sections which in turn comprise both concave and convex surfaces. The shape characteristics are related to geodesic as well as non-geodesic trajectories in regard of the fibres. Axial sections of the pressurizable structures can be rotated, expanded or bended with respect to the longitudinal axis of the pressurizable structure. Examples of uses of the pressurizable structure relate to pressure vessels and flexible pipelines, spring elements, robotic actuators and adaptable buildings. In another aspect, the invention relates to a method of production by means of braiding, which in principle allows for the construction of very large structures.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:13968388-c7c4-45e0-81cc-35126ca4c204","http://resolver.tudelft.nl/uuid:13968388-c7c4-45e0-81cc-35126ca4c204","Thin-film solar cell","Metselaar, J.W.; Kuznetsov, V.I.","","1998","The invention relates to a thin-film solar cell provided with at least one p-i-n junction comprising at least one p-i junction which is at an angle alpha with that surface of the thin-film solar cell which collects light during operation and at least one i-n junction which is at an angle beta with the light-collecting surface. In this context, the relationships 45 < alpha < 135 degrees and 45 < beta < 135 degrees apply. The invention also relates to a panel provided with a plurality of such thin-film solar cells and to methods for fabricating such a thin-film solar cell.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a08e4e99-9095-473f-8a4f-39592b3b03d5","http://resolver.tudelft.nl/uuid:a08e4e99-9095-473f-8a4f-39592b3b03d5","Epoxy-resin adhesive and method for bonding using such an epoxy resin adhesive","Bhowmik, S.; Poulis, J.A.; Benedictus, R.","","2008","The invention relates to an epoxy resin adhesive comprising a dotation of nano-substances, wherein the nano- substances are selected from the group comprising carbon-fibre nanotubes, carbon nano-fibres, silicate nano powders, and wherein the nano-substances are dispersed in the adhesive with a weight ratio of at least 1% and wherein the nano-substances are carbon-fibre nanotubes having a weight ratio of approximately 2%.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e83ee63d-d2b9-456b-a89c-2edc56b5fe0d","http://resolver.tudelft.nl/uuid:e83ee63d-d2b9-456b-a89c-2edc56b5fe0d","Device and method for the preparation of a mixture comprising fibre-reinforced thermoplastic pellets","Beukers, A.; Wiltink, F.J.; Van Breugel, J.H.","","2000","This material must be plasticised and in order to be able to process such a mixture by injection moulding or flow moulding it is necessary for, on the one hand, a rise in pressure and, on the other hand, mixing of the material to take place by means of the device. In order as far as possible to prevent damage to the fibres during a mixing, it is proposed to effect mixing using a piston/cylinder device (3, 4) in which a stirrer construction is fitted, consisting of a number of mixing rods (15, 16, 17) which rotate together with the piston (4). With this arrangement the mixing rods (15, 16, 17) essentially cover the entire surface of the volume to be mixed.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:63ae1ebe-e49c-43cb-8da6-6184dc2f4a20","http://resolver.tudelft.nl/uuid:63ae1ebe-e49c-43cb-8da6-6184dc2f4a20","Transmitter-receiver system","De Weerdt, E.; Van Kampen, E.J.; Chu, Q.P.","","2009","The invention relates to a transmitter-receiver system comprising at least three transmitters and at least a first receiver and a second receiver, wherein the receivers are connected to a computing device that is arranged to analyse signals that said receivers receive from said transmitters and to calculate length and attitude information of an imaginary baseline connecting said receivers depending on at least carrier phase information of said signals using interval analysis","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a32dadc4-af98-4822-9b69-57bf327e15aa","http://resolver.tudelft.nl/uuid:a32dadc4-af98-4822-9b69-57bf327e15aa","A morphing structure and method for morphing a structure","Pagitz, M.E.; Hol, J.M.A.M.","","2012","","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:424612d1-3341-42f5-bb53-5a69c40a38de","http://resolver.tudelft.nl/uuid:424612d1-3341-42f5-bb53-5a69c40a38de","Systeem en werkwijze voor energiewinning","Van der Tempel, J.","","2009","","","nl","patent","European Patent Office","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:ec3d9c91-7477-4e92-938f-50b5be6c308b","http://resolver.tudelft.nl/uuid:ec3d9c91-7477-4e92-938f-50b5be6c308b","Aircraft wing and fiber metal laminate forming part of such an aircraft wing","Alderliesten, R.C.; Rinze, B.","","2012","Fiber metal laminate (4)and an aircraft wing (1) having a longitudinal direction, comprising metal layers (5) and fiber reinforced plastic layers (6, 7, 6', 7'; 6'', 7'') in between said metal layers (5),wherein the metal layers (5) and the fiber reinforced plastic layers (6, 7, 6', 7'; 6'', 7'') are bonded together, and wherein the fibers of at least some of the fiber reinforced plastic layers (6, 7, 6', 7'; 6'', 7'') are arranged in a first group in a first plastic layer (6) and in a second group in a second plastic layer (7) whereby the fibers of the first group are at an angle with respect to the fibers of the second group, whereinsaid laminate (4) exhibits fibers of a first type and fibers of a second type, wherein the fibers of the first type being arranged in the said longitudinal direction of the laminate (4) in one or more of its fiber reinforced plastic layers (6', 7'; 6'', 7''), and that it has adjacent fiber reinforced plastic layers (6, 7) at or near a symmetry-plane of the laminate (4) that are provided with the fibers of the second type.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:cd5033a6-adf1-4130-8752-61aad5a5ffa6","http://resolver.tudelft.nl/uuid:cd5033a6-adf1-4130-8752-61aad5a5ffa6","Method and apparatus for vibration detection, method and apparatus for vibration analysis, lithographic apparatus, device manufacturing method, and computer program","Kok, H.V.; Kivits, K.; Van de Laak, R.; Kuiper, J.M.","","2007","A method is provided for determining information relating to vibration. The method includes projecting an aerial image at an image position in a projection plane; mapping an intensity of the aerial image into an image map that contains values of coordinates of sampling locations and of the intensity sampled at each sampling location; and measuring intensity of the aerial image received through a slot pattern. The method may also include determining from the image map a detection position of a slope portion of the image map; at the detection position of the slope portion, measuring a temporal intensity of the aerial image and relative positions of the slot pattern and the image position; and determining from the temporal intensity of the aerial image information relating to vibration for the aerial image.; The relative positions of the slot can be measured as position-related data of the slot pattern.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:5f314a8f-8794-442d-870a-a830363a7464","http://resolver.tudelft.nl/uuid:5f314a8f-8794-442d-870a-a830363a7464","Semi-finished product and method for obtaining it","Van den Akker, L.; Duurkoop, D.; Beukers, A.","","2010","The invention relates to a method for manufacturing a semi-finished product. The method comprises the steps of positioning a plurality of elongated reinforcing elements, excluding drawn polyethylene reinforcing elements, onto a mandrel, allocating in the thus produced product a first part and, distinct therefrom, a second part, fixating the reinforcing elements in the first part, and removing the semi-finished product from the mandrel. The invention also relates to a device for carrying out the method, and to a semi-finished product, comprising a first part with fixated reinforcing elements, excluding drawn polymeric reinforcing elements, and a distinct second part, and to a method for manufacturing a finished product from the semi-finished product.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:e5aa704d-bd26-4885-9288-d3c5ab09e246","http://resolver.tudelft.nl/uuid:e5aa704d-bd26-4885-9288-d3c5ab09e246","Method for treatment of a surface area of steel","Bhowmik, S.; Aaldert, P.J.","","2009","The invention relates to a method for treatment of a surface area of steel by polishing said surface area and performing a plasma treatment of said surface area wherein the plasma treatment is performed at at least atmospheric conditions and wherein the plasma treatment is carried out at a power of approximately 300 W and for a duration of at least 20 minutes, and preferably 30 minutes","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:24b5fc84-664e-4b1a-b965-70166cc04479","http://resolver.tudelft.nl/uuid:24b5fc84-664e-4b1a-b965-70166cc04479","Hot gas handling device and motorized vehicle comprising the device","Klein Geltink, J.; Beukers, A.; Van Tooren, M.J.L.; Koussios, S.","","2012","The invention relates to a device for handling hot exhaust gasses discharged from an internal combustion engine. The device comprises a housing (2), enclosing a space (3) for transporting the exhaust gasses. The housing (2) is provided with an entrance - opening (4) for the exhaust gasses discharged from the engine and an exit-opening (5) for transporting the exhaust gasses away from the engine, and comprises a flexible thermal insulating layer, arranged for resisting the temperature of the exhaust gasses discharged from the engine, and a supporting structure (8) at a side of the insulating layer opposite from the space, which supporting structure (8) is made of reinforcing fibres embedded in a matrix. The housing (2) further comprises a liner (16) of a porous fibrous structure facing the space (3). The invention relates further to a motorized vehicle provided with an internal combustion engine and an exhaust (1) according to the invention connected to the engine or a manifold of the engine.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:5658e1a8-4ed2-44f5-b9dd-3c68d5c03161","http://resolver.tudelft.nl/uuid:5658e1a8-4ed2-44f5-b9dd-3c68d5c03161","Inspection method and apparatus, and lithographic apparatus","Den Boef, A.; Kuiper, J.M.","","2010","A metrology device for inspecting a substrate is provided. In an embodiment, the metrology device includes a remote radiation source device, an optical system for creating a radiation beam, and an optical fibre for transferring radiation from the optical system to the location where the metrology operations are performed. The optical system includes a control system that includes a deformable mirror, a detector that detects the position of a radiation beam, and a controller that produces a control signal for input into the deformable mirror, the control signal being based on the detected position of the radiation. In this way, the shape of the deformable mirror can be used to control the position of the radiation beam output by the optical system into the optical fibre.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:5f445339-baa5-4765-a5ba-47928fa412bf","http://resolver.tudelft.nl/uuid:5f445339-baa5-4765-a5ba-47928fa412bf","Assembly comprising a loading container and a flexible receptacle","Beukers, A.; De Winter, S.E.E.; De Haan, P.A.J.","","1998","In order, in a loading container (1) for conveying goods, to reserve a larger or smaller part as desired for the transportation of bulk material and/or fluids, it is proposed to convey this bulk material (10) or these fluids in flexible receptacles (11) which, during filling, adopt an essentially parallelepipedal form which corresponds to the shape of the loading container. The opening (8) in these receptacles is attached to a corresponding opening in the loading container, via which the bulk material or the fluids can be introduced and removed.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9cb26c7a-8bf4-4339-8b06-18751ab6f8eb","http://resolver.tudelft.nl/uuid:9cb26c7a-8bf4-4339-8b06-18751ab6f8eb","Vessel, motion platform, method for compensating motions of a vessel and use of a stewart platform","Van der Tempel, J.; Salzmann, D.J.C.; Koch, J.; Gerner, F.; Goebel, A.J.","","2007","A vessel (1) with a motion compensation platform (4), which platform is provided with at least one carrier (6) for bearing, moving and/or transferring a load, actuators (5) for moving the carrier relative to the vessel, preferably in six degrees of freedom, a control system for driving the actuators (5), and motion sensors for measuring motions of the vessel (1) relative to the at least one element in the surrounding area, which measurements are used as input for the control system, wherein at least one at least partly passive pressure element (9) is provided for applying, during use, a pressure to the carrier for at least partly bearing this.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f4e66bd3-3d3b-4131-b720-102833a54775","http://resolver.tudelft.nl/uuid:f4e66bd3-3d3b-4131-b720-102833a54775","Device and method for calculating position of mobile station","Nakamura, M.; Tajima, Y.; Kagawa, K.; Teunissen, P.; Joosten, P.","","2009","A disclosed device for calculating a position of a mobile station using an integer ambiguity comprises a testing unit configured to evaluate reliability of observables on epoch basis, the observables including at least code data and carrier phase obtained at a single epoch. The testing unit includes a first testing unit configured to test residuals as a whole, and a second testing unit configured to test one or more items of the residuals separately.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:e0f42a67-ff47-4052-ab50-451ed7c9c601","http://resolver.tudelft.nl/uuid:e0f42a67-ff47-4052-ab50-451ed7c9c601","Pin/hole joint construction and laminate therefor","Labordus, M.; Van Tooren, M.J.L.; De Graaf, T.J.M.","","2004","A pin/hole joint construction in a laminate (1) comprises layers (9) of fibres and resin bonded to one another. At least one hole (2) extends transversely completely through the layers in the laminate, in which hole a pin (3) is accommodated that bears against the inner surface of the hole for transferring forces between the laminate and the pin. In the laminate a first region (13) is defined in which the layers are directly on top of one another and a second region (14) in which at least one reinforcing layer (5) is provided that is bonded to the adjacent layers of fibres and resin, in which second region the at least one hole is located. All layers of fibres and resin are continued into the second region.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b2d01078-3b5d-46d3-96b9-180637730702","http://resolver.tudelft.nl/uuid:b2d01078-3b5d-46d3-96b9-180637730702","Joint prosthesis and method of bone fixation","Oosterom, R.; Van der Pijl, A.J.; Bersee, H.E.N.; Van der Helm, F.C.; Herder, J.L.","","2006","The invention relates to a joint prosthesis (10), for example, a knee joint or shoulder joint prosthesis comprising a first, socket-holding prosthesis part (11) for attachment to a first bone (12) and a second, ball-holding prosthesis part (13) for attachment to a second bone (14) that intermates with the first prosthesis part, wherein the first bone and the second bone are situated at either side of a joint, and wherein the ball (2) of the second prosthesis part is rotatably received in the socket (5) of the first prosthesis part, wherein the first prosthesis part can be coupled with the first bone by applying tensile strain bearing rods (6), wherein when the mounted prosthesis is in a virtually unloaded condition, there is no significant tensile force in the rods.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b2bf053e-3bf9-4737-984e-0ad7509151ce","http://resolver.tudelft.nl/uuid:b2bf053e-3bf9-4737-984e-0ad7509151ce","Laminate and airplane provided with such a laminate","Alderliesten, R.C.; Rinze, B.; Rans, C.D.; Rodi, R.","","2012","","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:3c6b8fa0-9447-40a2-b52d-6797b5731219","http://resolver.tudelft.nl/uuid:3c6b8fa0-9447-40a2-b52d-6797b5731219","Telescopische loopbrug","Koch, J.; Van der Tempel, J.; Hessels, E.","","2008","","","nl","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4d804472-e4c3-4f8b-bfa6-46c8d49c9824","http://resolver.tudelft.nl/uuid:4d804472-e4c3-4f8b-bfa6-46c8d49c9824","Method and device for manufacturing a moulded part from a sheet-like material","Decoster, D.; Marissen, R.; Antonelli, V.","","2008","The invention relates to a method for manufacturing a moulded part from a sheet-like material (40). The method comprises the steps of providing a first mould half (10) of a form-retaining material; providing a second mould half (20) in the form of a collection of material particles (21) situated in enclosing means (22); deforming the sheet-like material (40) under pressure between the two mould halves (10,20). The invention also relates to a device (1) for performing the method and to a moulded part obtainable with the method.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ecc19e93-6837-4796-8d0b-5cf4caa9e656","http://resolver.tudelft.nl/uuid:ecc19e93-6837-4796-8d0b-5cf4caa9e656","Fiber metal laminate","Alderliesten, R.C.; Conen, M.","","2013","","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:18aa5ad9-4938-480b-96df-d83d0a2089fe","http://resolver.tudelft.nl/uuid:18aa5ad9-4938-480b-96df-d83d0a2089fe","Method for fabrication of a fiber metal laminate","Alderliesten, R.C.; Grashof, B.A.","","2012","","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:58f5ac04-d418-448f-8be4-76b47b3fb58a","http://resolver.tudelft.nl/uuid:58f5ac04-d418-448f-8be4-76b47b3fb58a","Method and apparatus for vibration detection and vibration analysis, and lithographic apparatus equipped with such an apparatus","Kok, H.V.; Kivits, K.; Van de Laak, R.; Kuiper, J.M.; Van der Zouw, G.; Tolsma, H.P.T.","","2010","The invention provides a method for determining vibration-related information by projecting an aerial image at an image position in a projection plane, mapping an intensity of the aerial image into an image map, the image map arranged for comprising values of coordinates of sampling locations and of the intensity sampled at each sampling location, and measuring intensity of the aerial image received through a slot pattern.; The method further includes determining from the image map a detection position of a slope portion of the image map, at the detection position of the slope portion, measuring of a temporal intensity of the aerial image and measuring of relative positions of the slot pattern and the image position, the relative positions of the slot being measured as position-related data of the slot pattern and determining from the temporal intensity of the aerial image vibration-related information for said aerial image.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:ecb94699-911e-42f5-be52-50ec3efdf92e","http://resolver.tudelft.nl/uuid:ecb94699-911e-42f5-be52-50ec3efdf92e","Self-supporting refrigerated truck","Beukers, A.; De Winter, S.E.E.; Brouwer, W.D.","","1997","Self-supporting refrigerated truck comprising a floor, two side walls, a front bulkhead and a roof. The components are all constructed as sandwich panels. The connection between the rear axle construction of the refrigerated truck and the front is not provided with longitudinal beams. The function of the chassis is taken over by the side walls (9), which are capable of absorbing loads because the skin and sandwich panels of the side walls have appreciable strength and a fill of appreciable compressive strength is also fitted. In order to transmit forces into the side walls it is proposed to accommodate the vertically extending trusses in said side walls, which trusses are joined to cross-members of the rear axle construction which extend over the entire width.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3a04a820-a45e-49db-bcb6-9de9c98852cb","http://resolver.tudelft.nl/uuid:3a04a820-a45e-49db-bcb6-9de9c98852cb","Method and device for manufacturing a product of a composite material of reinforcing elements","Beukers, A.; Bergsma, O.K.; Koussios, S.; D'Haeze, P.; Rommens, M.","","2011","","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:bc9b9c96-abcb-4b59-b361-0d678e0aabcd","http://resolver.tudelft.nl/uuid:bc9b9c96-abcb-4b59-b361-0d678e0aabcd","Laminate and airplane provided with such a laminate","Alderliesten, R.C.; Benedictus, R.; Rans, C.D.","","2012","","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:e6befc24-0957-4d29-a2ce-5a92afc30401","http://resolver.tudelft.nl/uuid:e6befc24-0957-4d29-a2ce-5a92afc30401","Helicopter","Voskuijl, M.","","2015","","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:5e05b85d-e24d-4afd-b147-ef1ae81b9445","http://resolver.tudelft.nl/uuid:5e05b85d-e24d-4afd-b147-ef1ae81b9445","Boor, en werkwijze voor het vervaardigen van een dergelijke boor","Snijder, J.","","1998","The drill head consists of a pointed end with cutting edges (5) on the ends of the flutes (3). The endface of the drill head, opposite the pointed end, incorporates a central blind hole (6). A separate drill shaft (2) has a cylindrical protrusion at its end which fits into the hole in the drill head to which it is attached by hard soldering. The drill head is made from a hard metal and is cut-of from a standard drill e.g by spark erosive machining which can also be used for making the hole in the endface of the head. The drill shank is made from a hardened steel.","","nl","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:affd2ab5-5bd1-4463-887d-0e9bbe46467f","http://resolver.tudelft.nl/uuid:affd2ab5-5bd1-4463-887d-0e9bbe46467f","Method for producing a nodal frame of interconnected structural members and flexible elongated material structure for use in the method","Beukers, A.; Bergsma, O.K.; Koussios, S.; D'Haeze, P.; Rommens, M.","","2011","","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:835ef112-b918-41d5-a27d-b0b36b456ab1","http://resolver.tudelft.nl/uuid:835ef112-b918-41d5-a27d-b0b36b456ab1","Load sensor","Van den Ende, D.; Almeida, P.M.R.; Dingemans, T.J.; Van der Zwaag, S.","","2007","The invention relates to a load sensor comprising a polymer matrix and a piezo-ceramic material such as PZT, em not bedded in the polymer matrix, which together form a compos not ite, wherein the polymer matrix is a liquid crystalline resin, and wherein the piezo-ceramic material is a PZT powder forming 30-60% by volume of the composite, and wherein the PZT powder forms 40-50% by volume of the composite.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9ed8b17a-fe85-44b0-8b14-9826ddebe1ad","http://resolver.tudelft.nl/uuid:9ed8b17a-fe85-44b0-8b14-9826ddebe1ad","Method for manufacturing an optimized motion simulator and optimized motion simulator","Advani, S.K.","","1999","The invention relates to a motion simulator comprising a deck supported by a number of length-adjustable legs that are connected to the deck in first pivot points, which legs are connected to a base part in second pivot points, wherein the first and second pivot points respectively form pairs, wherein: the first and/or second pivot points are located on an ellipse, at least in top plan view; and/or the angle included between at least two pairs of first pivot points and/or two pairs of second pivot points is less than 120 DEG ; and/or the adjusting range of at least one of the legs is greater than at least one of the other legs; and/or at least one of the second pivot points is located in a plane at a distance from the plane in which at least two further pivot points are located, and a method for the manufacture thereof.","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1f575ddc-5870-40f1-996a-e2a87fd7d926","http://resolver.tudelft.nl/uuid:1f575ddc-5870-40f1-996a-e2a87fd7d926","Method and device for loading packed goods using an intermediate load unit","Reijnen, R.; Ross, L.H.A.; Houlleberghs, B.R.Y.; Naber, J.; Van der Meulen, R.J.R.","","2009","The invention relates to a device for loading packed goods into a transport unit (8b), the device comprising an orientation unit for orienting each packed good in a predetermined direction, means for transferring the packed goods in the order of a predetermined loading sequence to the orientation unit, a load module, provided with an intermediate load unit for temporarily loading the packed goods in their oriented state, and means (25,26) for transferring the contents (28) of the intermediate load unit into the transport unit (8b) in one stroke. The invention further relates to a method for loading packed goods into a transport unit (8b).","","en","patent","European Patent Office","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3874af49-60eb-4775-a970-d98b764124c6","http://resolver.tudelft.nl/uuid:3874af49-60eb-4775-a970-d98b764124c6","Methodology for designing aircraft having optimal sound signatures","Sahai, A.K. (TU Delft Aircraft Noise and Climate Effects); Van Hemelen, T. (TU Delft Aerospace Engineering); Simons, D.G. (TU Delft Aircraft Noise and Climate Effects)","","2017","This paper presents a methodology with which aircraft designs can be modified such that they produce optimal sound signatures on the ground. With optimal sound it is implied in this case sounds that are perceived as less annoying by residents living near airport vicinities. A novel design and assessment chain has been developed which combines the aircraft design process with an auralization and sound quality assessment capability. It is demonstrated how different commercial aircraft can be designed, their sounds auralized at representative locations in airport vicinities and subsequently assessed for sound quality. As sound quality is closely related to the perceived annoyance, it is expected that designs with improved sound quality would also be perceived as less annoying. By providing a feedback to the design optimizer in terms of one of the sound quality metrics or a suitable combination thereof, the designs of aircraft can be altered to produce potentially less annoying sounds. The paper will focus on three current aircraft and will demonstrate the application of the novel design chain to auralize and alter their sounds toward improved sound quality. The presented methodology can also be extended to unconventional aircraft configurations and propulsion concepts, for optimizing future aircraft sounds.","","en","poster","","","","","","","","","Aerospace Engineering","","Aircraft Noise and Climate Effects","","",""
"uuid:105c1da1-e857-4012-b2e1-bedf14f38524","http://resolver.tudelft.nl/uuid:105c1da1-e857-4012-b2e1-bedf14f38524","Over vliegtuigen en mensen","Taub, J.","","1969","","Uittreerede","nl","public lecture","Uitgevrij Waltman Delft","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ae2bd9ae-6a0d-437e-a23c-ecfc0bbe7087","http://resolver.tudelft.nl/uuid:ae2bd9ae-6a0d-437e-a23c-ecfc0bbe7087","Theorie en experiment in de stromingsleer","Van Ingen, J.L.","","1971","","Intreerede","nl","public lecture","Uitgeverij Waltman Delft","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2a1a7bf3-ab91-4c23-a164-644c7bbd3a03","http://resolver.tudelft.nl/uuid:2a1a7bf3-ab91-4c23-a164-644c7bbd3a03","Goud","Ypma, P.J.","","1988","","Intreerede","nl","public lecture","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e5884c4b-0daa-4a63-8c90-7e0402e60b71","http://resolver.tudelft.nl/uuid:e5884c4b-0daa-4a63-8c90-7e0402e60b71","Over de ontwikkeling van de stromingleer","Steketee, J.A.","","1960","","Intreerede","nl","public lecture","Uitgeverij Waltman Delft","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4f9f2aa0-8d2f-4eb7-ace8-a839b83aff59","http://resolver.tudelft.nl/uuid:4f9f2aa0-8d2f-4eb7-ace8-a839b83aff59","Aerospace human-machine systems: From safety to where?","Mulder, M.","","2009","","Intreerede","en","public lecture","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b5afba83-a9f2-4814-b0a9-99bce119258f","http://resolver.tudelft.nl/uuid:b5afba83-a9f2-4814-b0a9-99bce119258f","Agent-based safety risk analysis of air traffic management","Blom, H.A.P.","","2013","","Intreerede","en","public lecture","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:13b5b1cf-1d3e-44b0-a724-44896cf157db","http://resolver.tudelft.nl/uuid:13b5b1cf-1d3e-44b0-a724-44896cf157db","Together in space: Potentials and challenges of distributed space systems","Gill, E.","","2008","","Intreerede","en","public lecture","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6fc5da1a-a58c-4c20-9339-406a2903f01c","http://resolver.tudelft.nl/uuid:6fc5da1a-a58c-4c20-9339-406a2903f01c","""Solar system exploration""","De Pater, I.","","2011","","Intreerede","en","public lecture","Delft University of Technology","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:e14ec911-bbd2-49ff-93c0-53de3115aef6","http://resolver.tudelft.nl/uuid:e14ec911-bbd2-49ff-93c0-53de3115aef6","Aerospace Polymers are Shaping up: Structural and functional properties can go hand in hand","Dingemans, T.","","","","Intreerede","en","public lecture","","","","","","","","","Aerospace Engineering","Aerospace Materials and Manufacturing","","","",""
"uuid:c80537e3-6b15-4836-a0f9-f427a97b0cd4","http://resolver.tudelft.nl/uuid:c80537e3-6b15-4836-a0f9-f427a97b0cd4","Spel van terugblik en perspectief","Van der Maas, H.J.","","1967","Uittreerede van Prof. dr. ir. Hendricus Jacobus van der Maas. Korte biografie: prof. dr. ir. H.J. van der Maas (1899-1987) studeerde in 1923 af aan de TU Delft (toen de Technische Hoogeschool), Maritieme Techniek. Direct daarna begon hij bij de Rijksstudiedienst voor de Luchtvaart (RSL) in Amsterdam. In 1925 behaalde hij zijn vliegbrevet. Hij promoveerde in 1929 op het proefschrift “Stuurstandslijnen van vliegtuigen; de bepaling ervan door middel van vliegproeven en hare beteekenis voor de beoordeeling der stabiliteit”. Tot 1937 werden alle nieuwe types verkeersvliegtuig door de RSI gekeurd. Mede door zijn onderzoeken kwam er in 1939 een leerstoel in de vliegtuigbouwkunde bij de afdeling Werktuigbouwkunde en Scheepsbouwkunde van de TH Delft. Hij werd de eerste hoogleraar in dit vakgebied. Tijdens de Tweede Wereldoorlog bleef Van der Maas doceren en onderzoek doen. In 1944 moest hij echter onderduiken nadat hij het studentenverzet had gesteund. Meteen na de bevrijding werd Van der Maas benoemd tot rector magnificus van de TH Delft. Zijn afdeling Vliegtuigbouwkunde, waarvan hij voorzitter-beheerder bleef, kreeg een eigen gebouw met laboratoria en windtunnels. In 1952 werd de Advisory Group for Aeronautical Research and Development (AGARD) opgericht als onderdeel van de NAVO. Van der Maas was medeoprichter en bleef Nederlands gedelegeerde tot 1971. In 1957 was hij medeoprichter van het International Council for the Aeronautocal Sciences (ICAS). Zijn verdiensten voor wetenschap en techniek werden beloond door zijn verkiezing, in 1959, tot lid van de Koninklijke Nederlandse Akademie van Wetenschappen, KNAW.","Uittreerede","nl","public lecture","W.D. Meinema N.V.","","","","","","","","Aerospace Engineering","","","","",""
"uuid:26abd415-6481-4056-a35c-7bd97aff1c9e","http://resolver.tudelft.nl/uuid:26abd415-6481-4056-a35c-7bd97aff1c9e","Anatomie van een uitvindersbrein: Hoe ontstaan radicaal innovatieve ideeën?","van Holten, Th.","","2007","","Uittreerede","nl","public lecture","Delft University of Technology, Faculty of Aerospace Engineering","","","","","","","","Aerospace Engineering","","","","",""
"uuid:64da6ca3-7835-466d-820b-02333b6cc618","http://resolver.tudelft.nl/uuid:64da6ca3-7835-466d-820b-02333b6cc618","De Start","van der Maas, H.J.","","1940","Intreerede van Prof. dr. ir. Hendricus Jacobus van der Maas. Korte biografie: prof. dr. ir. H.J. van der Maas (1899-1987) studeerde in 1923 af aan de TU Delft (toen de Technische Hoogeschool), Maritieme Techniek. Direct daarna begon hij bij de Rijksstudiedienst voor de Luchtvaart (RSL) in Amsterdam. In 1925 behaalde hij zijn vliegbrevet. Hij promoveerde in 1929 op het proefschrift “Stuurstandslijnen van vliegtuigen; de bepaling ervan door middel van vliegproeven en hare beteekenis voor de beoordeeling der stabiliteit”. Tot 1937 werden alle nieuwe types verkeersvliegtuig door de RSI gekeurd. Mede door zijn onderzoeken kwam er in 1939 een leerstoel in de vliegtuigbouwkunde bij de afdeling Werktuigbouwkunde en Scheepsbouwkunde van de TH Delft. Hij werd de eerste hoogleraar in dit vakgebied. Tijdens de Tweede Wereldoorlog bleef Van der Maas doceren en onderzoek doen. In 1944 moest hij echter onderduiken nadat hij het studentenverzet had gesteund. Meteen na de bevrijding werd Van der Maas benoemd tot rector magnificus van de TH Delft. Zijn afdeling Vliegtuigbouwkunde, waarvan hij voorzitter-beheerder bleef, kreeg een eigen gebouw met laboratoria en windtunnels. In 1952 werd de Advisory Group for Aeronautical Research and Development (AGARD) opgericht als onderdeel van de NAVO. Van der Maas was medeoprichter en bleef Nederlands gedelegeerde tot 1971. In 1957 was hij medeoprichter van het International Council for the Aeronautocal Sciences (ICAS). Zijn verdiensten voor wetenschap en techniek werden beloond door zijn verkiezing, in 1959, tot lid van de Koninklijke Nederlandse Akademie van Wetenschappen, KNAW.","Intreerede; H.J. van der Maas","nl","public lecture","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9e71e73e-0026-488d-a012-d1328e5c82bb","http://resolver.tudelft.nl/uuid:9e71e73e-0026-488d-a012-d1328e5c82bb","Ruimtevaart in beweging","Visser, P.N.A.M.","","2015","","Intreerede","en","public lecture","Delft University of Technology","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:ea49a9bd-9a33-4af0-824c-b24b12913565","http://resolver.tudelft.nl/uuid:ea49a9bd-9a33-4af0-824c-b24b12913565","Geodesy..., a space odyssey","Hanssen, R.F.","","2008","","Intreerede","nl","public lecture","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a89461a4-6bef-4577-9cb9-5556f3a6ce47","http://resolver.tudelft.nl/uuid:a89461a4-6bef-4577-9cb9-5556f3a6ce47","Let’s start the clear sky revolution: Intreerede prof. dr. H. G. C. Werij","Werij, H.G.C. (TU Delft Aerospace Engineering)","","2018","","","en","public lecture","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7f1915ce-9847-40f3-afbc-d36c4678fb20","http://resolver.tudelft.nl/uuid:7f1915ce-9847-40f3-afbc-d36c4678fb20","Damage and residual strength of ARALL laminates and 2024 T3 impacted by a projectile with a hemispherical nose","Vlot, A.","","1987","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:977c1537-0de5-4fde-9245-29d576fbe017","http://resolver.tudelft.nl/uuid:977c1537-0de5-4fde-9245-29d576fbe017","Developments in mathematical models of human pilot behaviour","Gerlach, O.H.","","1977","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4ee7377c-b60a-40ba-98c1-d0cedb0bc6bc","http://resolver.tudelft.nl/uuid:4ee7377c-b60a-40ba-98c1-d0cedb0bc6bc","De eigenschappen van het vleugelprofiel NACA 2412 met grenslaagafzuiging ten behoeve van draagkrachtsverhoging","Tennekes, H.","","1965","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3f289284-6299-4e85-be80-e17b30816f41","http://resolver.tudelft.nl/uuid:3f289284-6299-4e85-be80-e17b30816f41","On the aerodynamic optimization of supersonic wings","Bos, H.J.","","1983","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:876f1377-b354-4d41-b2db-aa80e3171547","http://resolver.tudelft.nl/uuid:876f1377-b354-4d41-b2db-aa80e3171547","Verslag van een studiereis door de Verenigde Staten van Noord Amerika","Schoyer, H.F.R.","","1978","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b6cba067-90eb-4e70-bb1c-f2d7b6f6e15e","http://resolver.tudelft.nl/uuid:b6cba067-90eb-4e70-bb1c-f2d7b6f6e15e","Some computational tools for the analysis of through cracks in stiffened fuselage shells","Rankin, C.C.; Brogan, F.A.; Riks, E.","","1992","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3e764a58-6bbe-446d-ad55-a488cf9a3f8b","http://resolver.tudelft.nl/uuid:3e764a58-6bbe-446d-ad55-a488cf9a3f8b","The initial buckling behaviour of flat and curved fibre metal laminate panels","Verolme, K.","","1995","","Initial buckling; postbuckling behaviour; flat plates; curved plates; GLARE; ARALL; spliced laminates; initial imperfections; effective width approach","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f0a6fd4f-0c28-4769-af26-64310a4af778","http://resolver.tudelft.nl/uuid:f0a6fd4f-0c28-4769-af26-64310a4af778","Moisture absorption of ARALL","Verbruggen, M.L.C.E.","","1985","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:261d1f49-56a3-42f9-8883-ad70ec6dbcd0","http://resolver.tudelft.nl/uuid:261d1f49-56a3-42f9-8883-ad70ec6dbcd0","Samenvatting van een ontwerpstudie voor een klein straalverkeersvliegtuig met grenslaagafzuiging","Torenbeek, E.","","1961","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1770cfa3-cc4a-4200-b5c5-32b846b06d29","http://resolver.tudelft.nl/uuid:1770cfa3-cc4a-4200-b5c5-32b846b06d29","Over de funktie e^sigma(theta) en de snelheidsverdeling om Eppler-profielen","Blom, J.J.H.","","1984","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ed1d814b-3d3d-41dc-8533-1b224c4cb178","http://resolver.tudelft.nl/uuid:ed1d814b-3d3d-41dc-8533-1b224c4cb178","The tensile-mode/shear-mode transition during fatigue crack growth under flight-simulation loading","Misawa, H.; Schijve, J.","","1986","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2bfc8a5e-0843-4f4e-9ac2-b6608cfef6b9","http://resolver.tudelft.nl/uuid:2bfc8a5e-0843-4f4e-9ac2-b6608cfef6b9","Vermoeing en duurzaamheid van gelijmde constructies","Schijve, J.","","1991","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:195c3146-81e2-4b4a-a61d-9f9cbffbce39","http://resolver.tudelft.nl/uuid:195c3146-81e2-4b4a-a61d-9f9cbffbce39","Optimization of the rubber cushion for the rubber pad forming process","Tel-Or, A.","","1993","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:10ed56bd-abc1-4934-b404-3b1e4a424119","http://resolver.tudelft.nl/uuid:10ed56bd-abc1-4934-b404-3b1e4a424119","Comparison between empirical and calculated stress intensity factors of hole edge cracks","Schijve, J.","","1983","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:adfec915-82d8-4b05-902d-0369af867fb0","http://resolver.tudelft.nl/uuid:adfec915-82d8-4b05-902d-0369af867fb0","Planning and simulation of taxiing aircraft using linear programming","Knijnenbrug, S.G.","","1998","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b4c23205-88db-4692-8b45-459d82f0c9ce","http://resolver.tudelft.nl/uuid:b4c23205-88db-4692-8b45-459d82f0c9ce","Tweejarige postdoctorale ontwerpersopleiding 'Luchtvaart- en Ruimtevaarttechniek': Evaluatie van de opleiding over de periode '91-'93","Pagen, M.J.","","1994","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1fbfdace-68af-4bf6-b83c-a8ce39b715e8","http://resolver.tudelft.nl/uuid:1fbfdace-68af-4bf6-b83c-a8ce39b715e8","Crack stoppers and ARALL laminates","Schijve, J.","","1989","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4b3f8094-2001-4ec2-a310-547471d19428","http://resolver.tudelft.nl/uuid:4b3f8094-2001-4ec2-a310-547471d19428","Linear temporal stability analysis: Of a thin layer of liquid sheared by an air stream","Moeleker, P.J.J.","","1996","","Linear stability analysis - Orr-Sommerfeld equation; anti-icing fluids - non-Newtonian power-law fluids; boundary-layers - free interface - Chebyshev polynomials","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7ce88b9f-04ba-4acf-a8ca-c79ba612c1f1","http://resolver.tudelft.nl/uuid:7ce88b9f-04ba-4acf-a8ca-c79ba612c1f1","High strain rate tests on fibre metal laminates","Vlot, A.","","1995","","Strain rate; residual strength; impact","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8de2bb48-4f7a-42a3-8127-cf360c72a00f","http://resolver.tudelft.nl/uuid:8de2bb48-4f7a-42a3-8127-cf360c72a00f","Imperfections measurement of Shell Liupf02, Liuip01 and Liuip02","Gunawan, L.","","1997","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4e23b22d-72a2-4d14-aacd-7afe3424cf27","http://resolver.tudelft.nl/uuid:4e23b22d-72a2-4d14-aacd-7afe3424cf27","Ground reflection effects on propeller aircraft noise spectra from flyover measurements","Ruijgrok, G.J.J.","","1978","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c2e75b4f-7661-4514-ace1-c392e90acc70","http://resolver.tudelft.nl/uuid:c2e75b4f-7661-4514-ace1-c392e90acc70","Toepassingen van de breukmechanika bij het spanningskorrosie onderzoek","De Jong, H.F.","","1975","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4dcd9721-5862-4721-a901-7e5228dba64b","http://resolver.tudelft.nl/uuid:4dcd9721-5862-4721-a901-7e5228dba64b","Relaxation due to temperature, moisture and external loading. Final results","Verbruggen, M.L.C.E.","","1984","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:079addb1-17b9-4634-be20-93bd1cfc6d7e","http://resolver.tudelft.nl/uuid:079addb1-17b9-4634-be20-93bd1cfc6d7e","Stochastic Flutter Analysis","Verhoosel, C.V.; Gutiérrez, M.A.; Hulshoff, S.J.","","2006","The field of fluid-structure interaction is combined with the field of stochastics to perform a stochastic flutter analysis. Various methods to directly incorporate the effects of uncertainties in the flutter analysis are investigated. The panel problem with a supersonic fluid flowing over it is considered as a testcase. The stochastic moments (mean, standard deviation, etc.) of the flutter point are computed by an uncertainty analysis. Sensitivity-based methods are used to determine the stochastic moments of the flutter point. This is done by implicit differentiation of the flutter requirement. The moments can also be determined using the spectral method, which can be considered as a projection method. An iterative solution to the general random eigenvalue problem is proposed for determining the spectral expansion of the flutter point. It turns out that the asymptotic method, which is a sensitivity-based method, is the most efficient method for approximating the moments of the flutter point. The success of this method can be explained by the fact that the relation between the random Mach number and the random field of elastic properties is close to linear. The probability of the occurrence of flutter below a specified Mach number can be computed using a reliability analysis. Fully sampling-based techniques are not applicable, since the required sample size would be to large. The probability of failure can be approximated without the use of sampling by the use of the first- and second-order reliability method. The results of these methods are inaccurate however. The importance sampling method combines the speed of the reliability methods with the accuracy of the sampling techniques to obtain an efficient approximation of the probability of flutter.","stochastic finite element methods; fluid-structure interaction; uncertainty analysis; reliability analysis; random eigenvalue problem","en","report","Delft Aerospace Computational Science","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:7570c571-9b13-4bb4-a46f-b8141c4a6701","http://resolver.tudelft.nl/uuid:7570c571-9b13-4bb4-a46f-b8141c4a6701","Application of marker load systems for fractography of fatigue cracks","Schijve, J.","","2014","","","en","report","TU Delft, faculty of Aerospace Engineering","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:89e17641-a3f5-4a7f-b34f-c3f48340ca5e","http://resolver.tudelft.nl/uuid:89e17641-a3f5-4a7f-b34f-c3f48340ca5e","Optimizing the rubber backed bending process","Ciantar, C.","","1993","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:990489f5-6f59-423f-9f25-85cc90705955","http://resolver.tudelft.nl/uuid:990489f5-6f59-423f-9f25-85cc90705955","The stress intensity factor of small cracks at notches","Schijve, J.","","1981","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e3738fda-130b-40c2-a24d-d0f03546e424","http://resolver.tudelft.nl/uuid:e3738fda-130b-40c2-a24d-d0f03546e424","Materials research in the sea: An investigation into the influence of environmental exposure on mechanical properties of glassfibre reinforced composites","van Dreumel, W.H.M.","","1980","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f887a980-88b2-4e68-b7e0-8b581260c6ae","http://resolver.tudelft.nl/uuid:f887a980-88b2-4e68-b7e0-8b581260c6ae","Over de stroming door VILEDON-filterdekens voor toepassing in windtunnels","Dobbinga, E.","","1987","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0222767e-64de-4548-9e3f-cee0041129e4","http://resolver.tudelft.nl/uuid:0222767e-64de-4548-9e3f-cee0041129e4","Onderzoek van een nagebootst niet-lineair regelsysteem","Peek, J.B.H.","","1959","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:285b3263-202d-4053-b4bc-d6cfbb5a1230","http://resolver.tudelft.nl/uuid:285b3263-202d-4053-b4bc-d6cfbb5a1230","Solid fuel combustion chamber: Progress report VII: Sixth phase, January-June 1985","Wittenberg, H.; Korting, P.A.O.G.; Vos, J.B.; Versmissen, J.P.M.; Wijchers, T.; van Dijk, J.H.","","1985","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:54c24ada-d607-4035-ba73-d9b94a00f9f9","http://resolver.tudelft.nl/uuid:54c24ada-d607-4035-ba73-d9b94a00f9f9","Multiple-site damage in aircraft fuselage structures","Schijve, J.","","1993","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:85739f97-ff6b-4f2c-bd63-2874ec83497f","http://resolver.tudelft.nl/uuid:85739f97-ff6b-4f2c-bd63-2874ec83497f","About the development of parallel algorithms for the solution of nonlinear boundary value problems","Arbocz, J.","","1989","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:74d72ed4-8042-4054-9914-ee7817e98faa","http://resolver.tudelft.nl/uuid:74d72ed4-8042-4054-9914-ee7817e98faa","Enige resultaten van geluidmetingen aan een licht schroefvliegtuig in statische toestand","Van Paassen, D.M.; Ruijgrok, G.J.J.","","1977","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:221b6949-86af-4989-9746-f8aff62bb05c","http://resolver.tudelft.nl/uuid:221b6949-86af-4989-9746-f8aff62bb05c","Stuurautomaten voor vliegtuigen: Deel I","van den Oever, M.J.","","1957","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a71f3317-4105-4ab4-9e43-47b6a659a322","http://resolver.tudelft.nl/uuid:a71f3317-4105-4ab4-9e43-47b6a659a322","Impact tests on fibre metal laminates under a tensile load","Vlot, A.","","1993","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0144a868-8927-4836-853b-c119b52743f7","http://resolver.tudelft.nl/uuid:0144a868-8927-4836-853b-c119b52743f7","Bepaling van de geometrische grootheden van Z-verstijvers. Een vergelijking tussen benaderingsmethoden en de exacte methode.","Gunnink, J.W.","","1979","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:19db592b-8934-4b12-bca2-674c136dc2af","http://resolver.tudelft.nl/uuid:19db592b-8934-4b12-bca2-674c136dc2af","Het effect van een driedimensionale bron op stroming door een kanaal met vierkante dwarsdoorsnede: Voorstudie voor het ontwerp van ophangstaken en voor de berekening van tunnelwandinvloed","Dobbinga, E.","","1987","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7fd53284-55a5-4d08-af06-270dc7cb2f24","http://resolver.tudelft.nl/uuid:7fd53284-55a5-4d08-af06-270dc7cb2f24","""Frequency and ventilation"": A survey of theoretical and experimental ventilation modelling","de Jongh, F.H.C.","","1990","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:05f6805a-6d79-4219-8c1e-521a6356d463","http://resolver.tudelft.nl/uuid:05f6805a-6d79-4219-8c1e-521a6356d463","Rapid solidification processing of Al-Cu-Li-Mg alloys","van der Brandt, B.; van den Brink, P.J.; de Jong, H.F.; Katgerman, L.; Kleinjan, H.","","1983","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:5d7ed6e9-ad88-49fe-9f6d-d613e5c562de","http://resolver.tudelft.nl/uuid:5d7ed6e9-ad88-49fe-9f6d-d613e5c562de","Metingen in assymetrische vluchten van het vliegtuig Auster ""Autocar"" J-5 B, PH-NEH","Lamers, G.L.","","1961","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2de3f065-6456-4316-be57-c328a5cde3c0","http://resolver.tudelft.nl/uuid:2de3f065-6456-4316-be57-c328a5cde3c0","De meting van het pompdiagram en de bepaling van een maat voor het pomptransport van de afzuiginstallatie in het vliegtuig Fokker S-12, PH-NDC","Lamers, G.L.","","1964","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2a5078cb-1f70-4cc3-bb8e-65b9dab3ac62","http://resolver.tudelft.nl/uuid:2a5078cb-1f70-4cc3-bb8e-65b9dab3ac62","Beschrijving van een computer programma voor de verwerking en analyse van VBVK-metintgen: Deel A","Klein Lebbink, G.C.","","1987","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:211d5e4e-bf11-4c71-8a43-6c43a5ce45a4","http://resolver.tudelft.nl/uuid:211d5e4e-bf11-4c71-8a43-6c43a5ce45a4","Stress analysis of adhesively bonded single lap joints: Survey and evaluation of analyses","van Ingen, J.W.; Vlot, A.","","1993","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:79e3d114-0166-48de-b9ce-b1031cb6f166","http://resolver.tudelft.nl/uuid:79e3d114-0166-48de-b9ce-b1031cb6f166","De bepaling van de weerstandscoefficient van geperforeerde huidplaat ten behoeve van grenslaagafzuiging","De Lange, P.","","1966","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:855f3c48-3c48-41f5-a5d6-ebe639781af1","http://resolver.tudelft.nl/uuid:855f3c48-3c48-41f5-a5d6-ebe639781af1","Boordeling van meetmethoden voor het schokgolf-grenslaagonderzoek in de TST-27 windtunnel","Lenselink, H.; Nebbeling, C.","","1982","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9576f44c-de1f-44e2-bd67-38054aed88c7","http://resolver.tudelft.nl/uuid:9576f44c-de1f-44e2-bd67-38054aed88c7","Interface between MEDUSA and GIFTS for shell structures","Notenboom, R.P.","","1988","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4af92666-7c28-456f-9d64-1a4bd446dfe6","http://resolver.tudelft.nl/uuid:4af92666-7c28-456f-9d64-1a4bd446dfe6","Design in the chair AeroSpace for Sustainable Engineering and Technology (ASSET)","Melkert, J.","","2007","","design; sustainability energy conversion; transport","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f45d38be-2fa8-42f9-96a1-bb87371222b9","http://resolver.tudelft.nl/uuid:f45d38be-2fa8-42f9-96a1-bb87371222b9","An estimate of heat transfer in L* burners","Schoyer, H.F.R.","","1978","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:229d5b27-68ab-4e0d-9aaf-b56de1d6c2d0","http://resolver.tudelft.nl/uuid:229d5b27-68ab-4e0d-9aaf-b56de1d6c2d0","Evaluation of the capabilities of supercomputers for shell collapse load calculations","Arbocz, J.; van Baten, T.J.; Llurba, R.","","1984","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8095d953-56d8-4ccc-93f0-8c764586faaa","http://resolver.tudelft.nl/uuid:8095d953-56d8-4ccc-93f0-8c764586faaa","On the error that can be induced by an ergodicity assumption","Scheurkogel, A.J.; Elishakoff, I.; Kalker, J.J.","","1980","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1dabb051-e28e-485d-986a-52b8315e8dbf","http://resolver.tudelft.nl/uuid:1dabb051-e28e-485d-986a-52b8315e8dbf","The effect of an irregular crack front on fatigue crack growth","Schijve, J.","","1980","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d50ee455-c225-43d2-bd07-e4d442392bc3","http://resolver.tudelft.nl/uuid:d50ee455-c225-43d2-bd07-e4d442392bc3","Navier-stokes solutions for laminar incompressible boundary layers with strong viscous-inviscid interaction","Heidsieck, R.D.","","1982","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7b14ef42-5d9a-4d7c-92f6-8a5b9c0bd9e6","http://resolver.tudelft.nl/uuid:7b14ef42-5d9a-4d7c-92f6-8a5b9c0bd9e6","Metingen in de vlucht van de stuurverplaatsing per ""g"" en de stuurkracht per ""g"" in afvangmanoevres en in zuivere bochten van het vliegtuig Auster ""Autocar"" J.5B. PH-NEH","Binkhorst, H.","","1960","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a6570db5-2b1f-4822-97e5-e43d67387149","http://resolver.tudelft.nl/uuid:a6570db5-2b1f-4822-97e5-e43d67387149","Basisdruk in supersone stromingen","van der Walle, F.","","1956","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b74b4632-c1d1-4277-aac5-29d44ef9f138","http://resolver.tudelft.nl/uuid:b74b4632-c1d1-4277-aac5-29d44ef9f138","A suitable transverse shear stiffness definition for buckling of laminates and sandwich plates","van Bladel, P.G.","","1989","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6a4421b2-35c2-4c9d-b7c3-0c97fe278456","http://resolver.tudelft.nl/uuid:6a4421b2-35c2-4c9d-b7c3-0c97fe278456","Het wikkelen van drukvaten volgens de ""netting"" theorie","de Jong, Th.","","1971","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:57afb9ed-0206-4ce1-bd12-f440aabafdb3","http://resolver.tudelft.nl/uuid:57afb9ed-0206-4ce1-bd12-f440aabafdb3","Solid fuel combustion chamber progress report XII: July-December 1987","Wittenberg, H.; Korting, P.A.O.G.; Zandbergen, B.T.C.; Wijchers, T.; Elands, P.J.M.; de Wilde, J.P.; Dijkstra, F.","","1988","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:51664828-fc0b-4d9f-9f4d-c8ad0865b196","http://resolver.tudelft.nl/uuid:51664828-fc0b-4d9f-9f4d-c8ad0865b196","Stresses around pin-loaded holes in elastically orthotropic plates with arbitrary load direction","de Jong, Th.; Vuil, H.A.","","1981","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:7ce4c8e2-9653-4294-b850-6fca38a09ea6","http://resolver.tudelft.nl/uuid:7ce4c8e2-9653-4294-b850-6fca38a09ea6","Applications of the parallel shooting method on the convex C-240","Deerenberg, E.; Jansen, E.L.","","1990","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:4815173f-a08c-4ad3-9c6f-a8d8586437bf","http://resolver.tudelft.nl/uuid:4815173f-a08c-4ad3-9c6f-a8d8586437bf","Magnetodynamische Couette stroming met variabele geleibaarheid over de kanaalbreedte","Nieuwstadt, F.","","1970","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:c604fc7f-8666-4994-84e3-c92d3c60f4ae","http://resolver.tudelft.nl/uuid:c604fc7f-8666-4994-84e3-c92d3c60f4ae","De berekening van het omspoeld gonderoppervlak van enkel- en dubbelstroom straalmotoren voor civiele vliegtuigen","Torenbeek, E.; Berenschot, G.H.","","1983","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ee6e171b-e41f-4f34-bb8c-22501be69aae","http://resolver.tudelft.nl/uuid:ee6e171b-e41f-4f34-bb8c-22501be69aae","Added Mass Effects of Compressible and Incompressible Flows in Fluid-Structure Interaction","Van Brummelen, E.H.","","2009","The subiteration method which forms the basic iterative procedure for solving fluid structure-interaction problems is based on a partitioning of the fluid-structure system into a fluidic part and a structural part. In fluid-structure interaction, on short time scales the fluid appears as an added mass to the structural operator, and the stability and convergence properties of the subiteration process depend significantly on the ratio of this apparent added mass to the actual structural mass. In the present paper, we establish that the added-mass effects corresponding to compressible and incompressible flows are fundamentally different. For a model problem, we show that on increasingly small time intervals, the added mass of a compressible flow is proportional to the length of the time interval, whereas the added mass of an incompressible flow approaches a constant. We then consider the implications of this difference in proportionality for the stability and convergence properties of the subiteration process, and for the stability and accuracy of loosely-coupled staggered time-integration methods.","fluid-structure interaction; added-mass effect; compressible and incompressible flow; subiteration","en","report","Delft Aerospace Computational Science","","","","","","","","Aerospace Engineering","Aerospace Materials & Manufacturing","","","",""
"uuid:29bb29c8-17d2-4a6c-bc03-933ccddeb7b3","http://resolver.tudelft.nl/uuid:29bb29c8-17d2-4a6c-bc03-933ccddeb7b3","Design and implementation of a new algorithm simulating the deformation of fabric reinforced plastics","Sikkema, J.M.; Bergsma, O.K.","","1993","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6911d49d-28b6-407b-81e2-adb75a7d3156","http://resolver.tudelft.nl/uuid:6911d49d-28b6-407b-81e2-adb75a7d3156","De prestaties van de afzuiginstallatie in het vliegtuig Fokker S-12X, PH-NDC, gemeten aan de grond en in de vlucht","Blom, J.J.H.; de Lange, P.","","1971","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:37d2fb84-fd05-406a-ba3c-452f767af697","http://resolver.tudelft.nl/uuid:37d2fb84-fd05-406a-ba3c-452f767af697","A note on the computation of the imperfection sensitivity of the collapse load of elastic structures","Riks, E.; Rankin, C.C.","","1994","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0773427d-b89d-45cc-95f3-f468ffd71892","http://resolver.tudelft.nl/uuid:0773427d-b89d-45cc-95f3-f468ffd71892","De verdeling van het getal van Mach in een beperkt gedeelte van de meetplaats van de supersone windtunnel no 2 bij een nominaal getal van Mach van 3","Bannink, W.J.","","1963","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2b5e0ecf-83ca-4ba0-8186-0da737290afa","http://resolver.tudelft.nl/uuid:2b5e0ecf-83ca-4ba0-8186-0da737290afa","Een onderzoek van hulpmiddelen ter verbetering van de snelheidsverdeling voor de schroef van modeltunnel","Boeker, J.","","1963","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:451c0a07-74ae-4e8d-b504-9ff7b7d8327f","http://resolver.tudelft.nl/uuid:451c0a07-74ae-4e8d-b504-9ff7b7d8327f","Computergesteund koncept ontwerpen van vliegtuigen","Bil, C.","","1987","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:73700fb3-7e62-4923-ac2f-99a79db129a1","http://resolver.tudelft.nl/uuid:73700fb3-7e62-4923-ac2f-99a79db129a1","Design of Hat-stiffened composite panels under uniaxial compression and shear - minimum mass optimization based on a simplified theory","Romeo, G.","","1981","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6c530c2f-6815-4cd2-b007-61f88595c9af","http://resolver.tudelft.nl/uuid:6c530c2f-6815-4cd2-b007-61f88595c9af","Treatment of boundaries in unsteady inviscid flow computations","de Neef, T.","","1978","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ffe280a1-5b05-40f0-bed8-551d22af15e0","http://resolver.tudelft.nl/uuid:ffe280a1-5b05-40f0-bed8-551d22af15e0","A one-dimensional analysis of acoustic pressure fluctuations in a simple rocket motor","Schoyer, H.F.R.","","1978","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:e0782158-46cf-4d70-9d86-2a1f9782f8b0","http://resolver.tudelft.nl/uuid:e0782158-46cf-4d70-9d86-2a1f9782f8b0","Jaarverslag van de stichting Studenten Vliegtuig- ontwikkeling bouw en beheer over 1991","","","1992","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:19aeca99-bc34-4bd8-9299-a8284841cb00","http://resolver.tudelft.nl/uuid:19aeca99-bc34-4bd8-9299-a8284841cb00","Handleiding voor het ijken van stijgsnelheidsmeters","Groep Handleidingen voor Practika ","","1953","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:05a8a49a-d7e4-4811-8bd6-c030c27cb0c9","http://resolver.tudelft.nl/uuid:05a8a49a-d7e4-4811-8bd6-c030c27cb0c9","Fatigue crack growth in 7475-T7651 material under flight-simulation loading. Information from a Douglas report","Schijve, J.","","1981","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:75a97d5c-2e69-4c04-a63a-e296bcb61fca","http://resolver.tudelft.nl/uuid:75a97d5c-2e69-4c04-a63a-e296bcb61fca","Opleiding tot vliegtuigbouwkundig ingenieur aan de universiteit van kansas: Enige vergelijkingen met de Delftse opleiding","Roskam, J.","","1977","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:76761184-7670-43a3-8768-c0b31302622f","http://resolver.tudelft.nl/uuid:76761184-7670-43a3-8768-c0b31302622f","Prediction methods for fatigue crack growth in aircraft material","Schijve, J.","","1979","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:77011f21-6c80-47de-bc72-fb9546d12fb1","http://resolver.tudelft.nl/uuid:77011f21-6c80-47de-bc72-fb9546d12fb1","Bepaling van de gunstigste plaats voor de ophangpunten van de vleugel van het windtunnelmodel van de F-27","","","1955","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:0fef22ca-0843-4231-99c0-b47269cb6fbf","http://resolver.tudelft.nl/uuid:0fef22ca-0843-4231-99c0-b47269cb6fbf","Numerical solutions of heat transfer problems in cylindrical geometries","Van der Geld, C.W.M.; Mies, J.A.M.A.; Ramaprabhu, R.","","1987","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:31ce5c4a-bb08-401e-8106-bf7da689ae96","http://resolver.tudelft.nl/uuid:31ce5c4a-bb08-401e-8106-bf7da689ae96","Handleiding van het programma Sapano [2.1]","Van Bladel, P.G.","","1988","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a7367c0d-9957-42d7-9796-d9206aec5cba","http://resolver.tudelft.nl/uuid:a7367c0d-9957-42d7-9796-d9206aec5cba","Verslag van bezoek aan Zweedse luchtvaartlaboratoria (KTH, FFA en Flygmotor)","Wittenberg, H.","","1959","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:ac741c52-8bcd-496d-a204-a8533fae66c8","http://resolver.tudelft.nl/uuid:ac741c52-8bcd-496d-a204-a8533fae66c8","Handleiding voor het gebruik van de versnellingsmeterijkinstallatie","van der Gon, J.J.D.","","1950","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3aed7058-e373-44f5-8fcc-2c5d87e3239c","http://resolver.tudelft.nl/uuid:3aed7058-e373-44f5-8fcc-2c5d87e3239c","The effect of low sheet thicknesses on the fracture toughness of an AL-Alloy (7075-T6)","Schijve, J.","","1984","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:02c56bdf-55ce-4517-8af9-9bc133adda40","http://resolver.tudelft.nl/uuid:02c56bdf-55ce-4517-8af9-9bc133adda40","Meting van een stijgvlucht van de De Havilland Tiger Moth PH-UCA","","","1950","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d1c1cb0d-f23a-4c19-8699-f8a2739b523e","http://resolver.tudelft.nl/uuid:d1c1cb0d-f23a-4c19-8699-f8a2739b523e","Theoretical analysis of laminar incompressible flow in slender channels","Klein Lebbink, G.C.","","1987","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:2f7e360c-597a-4ae7-b948-7c33038374cb","http://resolver.tudelft.nl/uuid:2f7e360c-597a-4ae7-b948-7c33038374cb","The influence of the deorbit-burn manoeuvre on the footprint of a re-entry capsule","Mooij, E.","","1993","","Aerospace technology; deorbit burn; re-entry; footprint; START","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:3d64eac4-5512-40a0-9ebc-42911a30629a","http://resolver.tudelft.nl/uuid:3d64eac4-5512-40a0-9ebc-42911a30629a","Hypersonic test facility Delft HTF-Delft","Bannink, W.J.; Bakker, P.G.","","1993","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d4acd26a-eb18-4ddb-be77-1930e24dc30f","http://resolver.tudelft.nl/uuid:d4acd26a-eb18-4ddb-be77-1930e24dc30f","Pre-design study of a general purpose vehicle simulator platform","Winkens, A.","","1992","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:d4a6eb70-fac1-4414-8c6c-05f90f3fcbfa","http://resolver.tudelft.nl/uuid:d4a6eb70-fac1-4414-8c6c-05f90f3fcbfa","Windtunnelonderzoek naar de toepassing van een gedeeld richtingsroer als luchtrem voor de Fokker F27 ""Friendship""","Binkhorst, H.","","1971","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b84c0d30-7078-42fe-b603-8ac6f2c6ce7b","http://resolver.tudelft.nl/uuid:b84c0d30-7078-42fe-b603-8ac6f2c6ce7b","The plane couette- and poiseuille-flow in M H D","Steketee, J.A.","","1971","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:df68d669-0539-44c2-b0c4-de74e8ce3683","http://resolver.tudelft.nl/uuid:df68d669-0539-44c2-b0c4-de74e8ce3683","Modern composites for primary aircraft structures","Spies, G.J.","","1985","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9f7dcf31-1343-4579-8f4b-6c81bad6be11","http://resolver.tudelft.nl/uuid:9f7dcf31-1343-4579-8f4b-6c81bad6be11","Luchtvaartkundig onderzoek, nu en in de toekomst","Wittenberg, H.","","1967","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f4940dc5-4b26-4519-b200-d1c49f25f50e","http://resolver.tudelft.nl/uuid:f4940dc5-4b26-4519-b200-d1c49f25f50e","Het corrosiegedrag van diverse las-, lijm- en klinkvervindingen in zeewater","Draisma, J.; Vogelesang, L.B.","","1974","","","nl","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:a22c6009-65df-4629-a594-6e428b5b38d5","http://resolver.tudelft.nl/uuid:a22c6009-65df-4629-a594-6e428b5b38d5","The calculation of chemical reacting turbulent boundary layers using the cray-1 supercomputer","Vos, J.B.","","1986","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:1f70cfc2-d644-492e-b806-8fe16a644380","http://resolver.tudelft.nl/uuid:1f70cfc2-d644-492e-b806-8fe16a644380","Effecten van corioliskrachten op rotorbladdynamica","van Gool, P.C.A.","","1994","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:6864433b-ee5a-46bd-89dd-32bb7f614159","http://resolver.tudelft.nl/uuid:6864433b-ee5a-46bd-89dd-32bb7f614159","An assesment of the static strength of flush head aluminium alloy rivets in two grades of ""ARALL"" sheet","Gunnink, J.W.; Rothwell, A.","","1983","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:9cd0be6a-7b02-4e4c-8080-c17364bdb3ed","http://resolver.tudelft.nl/uuid:9cd0be6a-7b02-4e4c-8080-c17364bdb3ed","Interface between MEDUSA and GIFTS for beam cross-sections","Notenboom, R.P.","","1987","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""