trajectory. The comfort parameter quantifies comfort in a similar manner based on the metrics lateral quickness, maximum lateral and longitudinal jerk, and standard deviation of lateral and longitudinal jerk. The final quantification scores are comprised of a value between 0 and 1 for both the safety and comfort parameters. A perfect score of 0 would indicate all metrics were identical, or better than the optimized reference trajectory. A value of 1 indicates a crash for the safety parameter, and highly uncomfortable driving for the comfort parameter. The resulting quantification framework is scenario-specific as the quantification is performed relative to an optimized reference trajectory.","Automated driving systems; take-over requests; Quantification; Optimization; trajectory planning","en","master thesis","","","","","","","","2024-06-01","","","","","","" "uuid:fa661ab6-0324-4115-adc8-0c8665e2e1d9","http://resolver.tudelft.nl/uuid:fa661ab6-0324-4115-adc8-0c8665e2e1d9","Techno-economic assessment of grid connected Power to Heat and Power to Hydrogen technologies: An electricity market scenario approach","Chintada, Priyanka (TU Delft Electrical Engineering, Mathematics and Computer Science)","Zaayer, Michiel (mentor); Morales-Espana, G (mentor); Watson, Simon (graduation committee); de Vries, Laurens (graduation committee); Delft University of Technology (degree granting institution)","2019","Wind energy is the most promising renewable energy source for the Netherlands in the energy transition period. However, the investment costs of the offshore wind are huge. Until now, the government was supporting the investments in wind farms with subsidy schemes irrespective of the electricity market dynamics. The latest large-scale offshore wind projects in Germany and the Netherlands (Hollandse Kust Zuid 1 and 2) have been awarded zero-subsidy. However, in the Netherlands, the transmission costs of the offshore wind electricity are socialized. This would force the un-subsidized wind-farms to feed their electricity into the public grid exposing them directly to the whole sale electricity market. With large shares of wind penetration in the market, the value of the electricity is declining. At the same time, the intermittent nature of the renewable energy sources generates large demand for flexibility in the electricity system. These pros and cons of renewable energy sources create new opportunities for electrification of other sectors to support achieving Paris climate agreement goals of the country. Heat and hydrogen sectors are identified as potential flexibility options to facilitate the de-carbonization of the energy system by 2050. European electricity market simulation model COMPETES is identified as potential tool to assess the integrated systems at national level. However, the flexibility provided by heat and hydrogen demands with thermal and hydrogen storage technologies is not part of the model directly. Therefore, an optimization model is developed to determine the size of power to heat and power to hydrogen systems with least cost. The results of this problem determine the outlook for investments in power to heat and power to hydrogen technologies. The problem also determines the operational strategy of these units in response to the hourly power prices. Consequently, the coupled implications of the emerging electricity load from heat, hydrogen markets on the national power system is studied. Industrial heat, domestic district heat networks currently provided by combined heat and power gas plants in the Netherlands and the developments in hydrogen consumption market are taken as study cases for assessment. This work provided insights about the opportunities, threats and solutions for the involved stakeholders.","Power to heat; Power to hydrogen; Electricity market model; Optimization; Renewables","en","master thesis","","","","","","","","","","","","","","" "uuid:2b697477-7d59-4083-b51d-70c0d3137261","http://resolver.tudelft.nl/uuid:2b697477-7d59-4083-b51d-70c0d3137261","Time Optimization for Laser Sailing Races","Pardo Arteaga, Gabriela (TU Delft Mechanical, Maritime and Materials Engineering)","Heemink, Arnold (mentor); Delft University of Technology (degree granting institution)","2019","Sailing against the wind follows a zig-zag trajectory. To find the optimal time and path-trajectory to move from one target to another during a race, this study analyzes how the wind determines the optimal time-path of Lasers, one of the smallest sailboats that compete during the summer Olympic Games.

To answer this question, this study uses four wind models in an algorithm developed in MATLAB to find the optimal time-path. The wind models were forecasts and wind measurements for the area of race R1 from the World Cup Series 2018 at Hyères, France. One of the wind models used were a Weather Research and Forecasting model (WRF) with a grid resolution of 1km, a time step of 10 minutes. On the other hand, the most basic model was a constant and uniform wind field. The race R1 has three lines, limited by two buoys, and one point(buoy), one line and one point define a leg. R1 has five legs and two of them are against the wind. The results, time and path-trajectories, of each of the wind models, were compared with the results of the top 10 winners of the race. They showed that the legs sailed against the wind are also characterized by the location of the sailboats on the start line. The times of these legs using the WRF wind model and the race-time had an error of less than 5%. For the prediction of the start location, it was the same as the winner of the race. However, the direction of the paths was not predicted accurately for these legs. Using the constant and uniform wind scenario, the percentage error of the race-time respect to the winner is about 7%. However, the direction of leg 2 is not even similar to the winner. To review the effects of the heights of the waves this study proposes to model the sailboat in 3-dimensions including the X-coordinate of the sail-man position. In addition, a 3D model allows the analysis of how the center of effort (CE) on the sail is affected by the current and waves.","Sailing; time; Optimization; Laser; Wind","en","master thesis","","","","","","","","","","","","Mechanical Engineering | BioMechanical Design","","" "uuid:4a40e302-bdf1-4319-81de-a6aad9376d65","http://resolver.tudelft.nl/uuid:4a40e302-bdf1-4319-81de-a6aad9376d65","Multi-point aerodynamic shape optimization for airfoils and wings at supersonic and subsonic regimes","Mangano, Marco (TU Delft Aerospace Engineering)","la Rocca, Gianfranco (mentor); Martins, Joaquim (mentor); Veldhuis, Leo (graduation committee); Dwight, Richard (graduation committee); Delft University of Technology (degree granting institution)","2019","The second-generation of supersonic civil transport has to match ambitious targets in terms of noise reduction and efficiency to become economically and environmentally viable. High-fidelity numerical optimization offers a powerful approach to address the complex trade-offs intrinsic to this novel configuration. Past and current research however, despite proving the potential of such design strategy, lacks in deeper insight on final layouts and optimization workflow challenges. Stemming from the necessity to quantify and exploit the potential of modern design tools applied to supersonic aircraft design, this work partially fills the gap in previous research by investigating RANS-based aerodynamic

optimization for both supersonic, transonic and subsonic conditions. The investigation is carried out with the state-of-the-art, gradient-based MDO framework \textit{MACH}, developed at University of Michigan's MDO Lab - which hosted the author for the 14-month research stint. Details of the tool and a brief overview of supersonic aircraft design and modern aerodynamic optimization strategies are reported in the first part of this manuscript.

After circumscribing the research niche, I perform single and multi-point optimization to minimize the drag over an ideal supersonic aircraft flight envelope and assess the influence of physical and numerical parameters on optimization accuracy and reliability. Leading and trailing edge morphing capabilities are introduced to improve the efficiency at transonic and subsonic flight speed by relaxing the trade-offs on clean shape optimization. Benefits in terms of drag reduction are quantified and benchmarked with fixed-edges results. It is observed how the optimized airfoils outperform baseline reference shapes from a minimum of 4\% up to 86\% for different design cases and flight

conditions. The study is then extended to the optimization of a planar, low-aspect-ratio, and low-sweep wing, using the same schematic approach of 2D analysis. I investigate the influence of wing twist alone and twist and shape on cruise performance, obtaining a drag reduction of 6\% and 25\% respectively as the optimizer copes with both viscosity and compressibility effects over the wing. Results for 3D multi-point optimization suggest that the proposed strategy enables a fast and effective design of highly-efficient wings, with drag reduction ranging from a minimum of 24\% up to 74\% for cruise at different speeds and altitudes, including edge deflection. Ultimately, this work provides an extensive and, to the best of author knowledge, unprecedented insight on the optimal design solutions for this specific aircraft configuration and the challenges of the optimization framework. The benefits of RANS-based aerodynamic shape optimization to capture non-intuitive design trade-offs and offer deeper physical insight are ultimately discussed and quantified. Given the promising results in terms of performance improvements and design efficiency, it is hoped that this work will foster the implementation of this method for more comprehensive full-configuration, multidisciplinary supersonic aircraft optimization studies.","Optimization; Aerodynamics; MDO; CFD; Supersonic; wing design; Airfoil; morphing; Gradient-based Optimization","en","master thesis","","","","","","","","","","","","Aerospace Engineering","","" "uuid:6b890080-8a60-4189-89dc-b12f23a8677a","http://resolver.tudelft.nl/uuid:6b890080-8a60-4189-89dc-b12f23a8677a","Orienting phylogenetic networks","Verzijlbergen, Esmay (TU Delft Electrical Engineering, Mathematics and Computer Science)","van Iersel, Leo (mentor); Jones, Mark (graduation committee); Keijzer, Marleen (graduation committee); Delft University of Technology (degree granting institution)","2019","This thesis provides you with basic information on graph theory as well as phylogenetic networks, it studies the relationship between undirected (unrooted) and directed (rooted) phylogenetic networks, based on the manuscript 'Rooting for phylogenetic networks' . Undirected phylogenetic networks can be oriented to become a directed network. In this manuscript the authors come up with multiple algorithms for orienting phylogenetic networks meeting different characteristics. A network is built up of reticulation vertices (where lineages merge) and tree vertices (where lineages separate). A network can be binary, meaning every node in the body of the network has a degree of three or a network can be non-binary, meaning there are no restrictions to the amount of edges a vertex can have.

When a network is binary, an algorithm is described that given the location of the root as well as a set of reticulation points, is used to find an orientation (Algorithm 1). If a network is non-binary, an algorithm is described that given a location of the root as well as the indegree of each vertex, is used to find an orientation (Algorithm 2 ). Once an orientation is found for a certain undirected network this orientation can be checked to see whether it meets the characteristics of a certain network class. Three network classes are considered. First of all an orientation can be tree-child, meaning that every non-leaf vertex has a child that is not a reticulation. Secondly an orientation can be stack-free, meaning that no reticulation has a child which is a reticulation. And last, an orientation can be valid, meaning that it is stack-free and deleting a single reticulation edge and suppressing its endpoints does not give parallel arcs. When we either did not find an orientation in the class we wanted or want to know all the orientations for a certain network in a certain class, we use Algorithm 3 or 4. The location of the root and the set of reticulation points were necessary input for Algorithm 1; whereas Algorithms 3 and 4 do not require this information. Algorithm 3 returns you the first found orientation in the class you wanted and Algorithm 4 returns you a collection of all orientations in the class. All orientations found by the program are returned in an output format that can be read by a network visualisation website.","Optimization; Phylogenetic network; Orientation model","en","bachelor thesis","","","","","","","","","","","","","","" "uuid:7d3bb76b-2957-46e4-9a26-85350f8975ae","http://resolver.tudelft.nl/uuid:7d3bb76b-2957-46e4-9a26-85350f8975ae","Factors affecting container transshipment volumes at ports:: A data driven holistic modelling approach","Veldstra, Tijmen (TU Delft Mechanical, Maritime and Materials Engineering)","Frouws, Koos (mentor); Hekkenberg, Robert (mentor); Beelaerts van Blokland, Wouter (mentor); Helbing, Jolke (mentor); Delft University of Technology (degree granting institution)","2019","In 20 years, from 1996 to 2016, global cumulative container port throughput had an average annual growth rate of 6.3%. Furthermore, the average global transshipment incidence increased from 11% in 1980 to a stable 27% in 2017. This change in transshipment market dynamics has led to opportunities for potential port investments or disinvestments. In this research, a tool is developed for Royal HaskoningDHV that improves transshipment forecasts. The developed tool calculates the optimal ports for transshipment, transshipment throughput volumes, fleet utilization, and optimal cost routes. This is done by means of minimizing the total transport costs, while meeting container demand requirements and port and vessel constraints. The most statistically significant factors affecting transshipment volumes are incorporated in the tool. By modifying input parameters, the tool facilitates calculations of optimal cost future transshipment port throughput volumes. This could provide key insights in lucrative port investment or disinvestment opportunities.","Container shipping; Hub and Spoke; Transshipment; Mixed Integer Linear Programming; Optimization","en","master thesis","","","","","","","","2049-04-24","","","","","","" "uuid:72d06941-c975-4d51-8d4b-a976a7c0b9cf","http://resolver.tudelft.nl/uuid:72d06941-c975-4d51-8d4b-a976a7c0b9cf","A practical maintenance task packaging model applicable to aircraft maintenance","Witteman, Max (TU Delft Aerospace Engineering)","Deng, Qichen (mentor); Lopes Dos Santos, Bruno (mentor); Delft University of Technology (degree granting institution)","2019","This research concerns the problem of scheduling aircraft maintenance tasks, that must be carried in multiple maintenance checks to keep the aircraft airworthy. During this research the allocation of maintenance tasks to their maintenance opportunities is referred to as the task allocation problem. It is a complex combinatorial problem that is solved daily by aircraft operators.We propose a novel two-stage framework capable of solving the task allocation problem, for an entire fleet. A Mixed-Integer Linear Programming (MILP) formulation was developed for both stages of the framework. In the first stage an exact method is used to pre-determine the workforce to allocate per day to each aircraft under maintenance. In the second stage, the task allocation problem is solved in- dependently for each aircraft, allocating task at the work shift level and per workforce skill. Moreover, an approximation algorithm is proposed, using bin packaging problem solution techniques, for both stages of the framework.Both stages were tested and validated using data of 45 aircraft from a European airline. The compu- tational performance of the approximation algorithm is benchmarked using a MILP formulation, solved with a commercial solver. Results indicate that the solution quality of the proposed algorithm remains excellent and runs up to 26 times faster than the exact method.This research is the first to present an optimization model to solve the maintenance task allocation problem, being solved at the work shift level. Furthermore, it presents a bin-packaging approximation algorithm that can be solved within minutes for the 45 aircraft fleet and a planning horizon of 4 years. The framework was validated in practice and the results give insights on the potential benefit of using such framework to solve this daily recurrent problem.","Maintenance; Optimization; Task allocation; Practical; Airline","en","master thesis","","","","","","","","","","","","Aerospace Transport & Operations","","" "uuid:bb7dbde7-31ae-4915-b733-5742e30b50ef","http://resolver.tudelft.nl/uuid:bb7dbde7-31ae-4915-b733-5742e30b50ef","Integral Internal Transport Planning and Coordination of Multiple Assets and Resources for turnaround of Aircraft for KLM at Amsterdam Airport Schiphol","Vos, Peter (TU Delft Mechanical, Maritime and Materials Engineering)","Beelaerts van Blokland, Wouter (graduation committee); Negenborn, Rudy (mentor); Delft University of Technology (degree granting institution)","2019","Currently, KLM's apron processes work in separate silos and there is only minimal integration. The result is that processes tend to work to a local optimum instead of a global optimum. A Transport Logistic Control Tower is a centralized information hub from which integral decisions can be made which could benefit the overall turnaround process at Schiphol airport. There is little knowledge about the effects on the system performance when input parameters are varied. A uniform way of scheduling tasks and making integral decisions is missing. The goal of this research is to determine the integral control scenario that should be used by a Transport Logistic Control Tower in order to optimize the overall performance of KLM's apron processes. The main research question is formulated as: Which integral control scenario should be used by a Transport Logistic Control Tower in order to optimize the overall performance of KLM's apron processes? In the current state analysis the Delft Systems Approach is used in combination with swim lane analyses to analyze the current system. Relations between the different processes, how they interact and the decisions that are made to plan their tasks are analyzed to get a better understanding of the apron processes. To asses the performance of the apron processes, the On Time Start (OTS), On Time Performance (OTP) and the On Time Delivery (OTD) are introduced. The number of flight delays and the corresponding costs are used to combine the process KPIs in order to make a final decision on the best control scenario for KLM. A thorough data analysis is performed by combining the multiple data sources of KLM to get insight in the performance of the system. This showed us that the data quality is not sufficient, and data does not correspond well with the real system. It is therefore recommended to use historical data in combination with the current calculation methods to improve the way the task duration is calculated. This also means that the way data is stored in the HHT should be automated to reduce the amount of measurement errors. A simulation model is designed to assess different control scenarios and the effect they have on the KPIs. The one day run shows significant improvements when dynamic flight priorities are used in combination with a departure oriented control scenario that schedules based on departure time. Compared to the same control scenarios using static priorities, an average improvement of 31,1\% or 1,7 million euros annually could be seen in the delay costs. This control scenario is therefore recommended and shows the necessity to use a uniform way of planning and the potential of the proposed dynamic flight priorities. The recommendations are done based on the analyses and the found results, and used to advice KLM on their future control scenario for their apron processes and improvement levers from which they could benefit in the future.","Optimization; KLM; Apron","en","master thesis","","","","","","","","2022-03-27","","","","","","" "uuid:588a8ded-1f59-42ca-9eb5-94f2e1e996b8","http://resolver.tudelft.nl/uuid:588a8ded-1f59-42ca-9eb5-94f2e1e996b8","Expanding the Abalities of Impact Testing for Rubber Characterization: Using an inverse approach for extracting material properties","de Roos, Wouter (TU Delft Mechanical, Maritime and Materials Engineering)","de Klerk, Dennis (mentor); Pasma, Eric (graduation committee); Delft University of Technology (degree granting institution)","2019","Vibrations are experienced as unwanted dynamic motions and the industry takes a lot of care to reduce these motions to improve comfort and to increase vehicle component durability. The properties of rubber, being generally soft while showing large inherent damping, makes the material a perfect choice to use in vibration isolators. To minimize vibrations the transfer path from vibrational source to the driver almost always includes a highly damped material like rubber. With the current trend of electrification in the automotive industry, higher order vibrations are becoming more pronounced. Although the produced sound is not of a high octave with respect to traditional combustion engines, they are experienced as unpleasant. Considering a large frequency range, the dynamic characterization of a rubber object is proven to be a difficult topic. In the search of improved rubber characterization new methods arise. The goal of this research is to provide a new approach for extracting material properties from the experimental impact method. Literature research is done on the rubber specific behaviour and how this affects the modelling approach. In the research itself both numerical and experimental characterization is used. Through impact testing the receptance of the rubber object is measured and by applying inverse substructuring the dynamic stiffness is obtained. The Finite Element model is used to directly obtain the dynamic stiffness. The numerical and experimental results are made comparable by applying the virtual point transformation method. With the finite element material model being the optimization variable, the numerical dynamic stiffness is optimized to match the experimental results. The rubber properties are obtained from the optimized material model. The presented inverse approach makes it possible to use the impact method for characterizing rubber material properties. It therefore broadens the abilities of impact testing used for rubber characterization. With the new method the drivingpoint properties can be predicted which do not depend on complex decoupling methods. The obtained material properties are material, but not geometry related. The findings can be used for different geometries of the same rubber. The new approach has the ability to significantly reduce experimental effort because the material properties can be extracted from one single loadcase, whereas the experimental should excite all loadcases to fully characterize the dynamic stiffness.","Rubber; Characterization; Impact testing; Optimization","en","master thesis","","","","","","","","","","","","","","" "uuid:24ce69c5-9994-42ef-89ce-26114555e970","http://resolver.tudelft.nl/uuid:24ce69c5-9994-42ef-89ce-26114555e970","The Hybrid Power Plant: Optimal design and operation of battery energy storage as an addition to onshore wind farms in the Netherlands","Sijtsma, Lennard (TU Delft Mechanical, Maritime and Materials Engineering)","de Jong, Wiebren (mentor); Heijnen, Petra (graduation committee); Ramaekers, Lou (graduation committee); Delft University of Technology (degree granting institution)","2019","In the Netherlands, wind power has the highest potential for future development compared to alternatives such as solar PV and biomass. The intermittent nature of the wind power resource calls for novel approaches to supply and demand management, as well as power quality assurance. Energy storage technologies allow for the separation between power generation and power supply to the grid. The energy and power densities, efficiency and response times of secondary batteries make them highly suitable for utility scale application to wind farms. However, a knowledge gap exists on exact configurations of battery energy storage systems for wind farms within the existing power markets. This study proposes a hybrid power plant approach, combining an onshore wind farm with a battery energy storage system. Literature research identifies balance between power obligation and production as a main design criterium, along with the profitability of a configuration and operational strategy. A technical analysis establishes power fluctuation on multiple time scales as relevant wind power characteristics, and maximum depth of discharge, discharge rates and efficiency as important battery parameters. A detailed analysis of the Dutch power market structure identifies three accessible markets for trade: the Day Ahead Market, the primary reserve (FCR) and the secondary reserve (aFRR). For modelling and optimization purposes, FCR is not considered due to excessive uncertainties regarding bid acceptance and bid activation. The design phase of the study is charged with finding the optimal battery capacity for a given wind farm production, while assuring the obligation to the Day Ahead Market is met. A linear optimization model is developed with the objective to maximize the obtained revenue. It is shown that the optimal battery capacity scales with the power capacity of the wind farm. For a 60 MW wind farm, the optimal battery capacity lies within the range of 60 – 80 MWh. An operational model is designed based on the model of the plant established in the design phase, elaborated with a Model Predictive Control approach. Based on wind power generation forecasts, the algorithm is able to adjust the charge/discharge and imbalance settlement strategy continuously based on expected market price series. However, the low level of accuracy of the applied market price approximations lead to unprofitable results in all simulated cases. Market price approximations with increased accuracy, as well as reduction of battery installation costs may lead to profitable operation of a hybrid power plant.","Wind Energy; Batteries; Optimization; Modelling; Wind Farm","en","master thesis","","","","","","","","","","","","Mechanical Engineering | Energy and Process Technology","","" "uuid:00eb0f82-5213-4657-8fa4-2630c3594463","http://resolver.tudelft.nl/uuid:00eb0f82-5213-4657-8fa4-2630c3594463","Decentralized coordination for area surveillance purposes","Demetriou, Kyriakos (TU Delft Mechanical, Maritime and Materials Engineering)","Sijs, Joris (mentor); Fransman, Jeroen (mentor); De Schutter, Bart (graduation committee); Ferrari, Riccardo (graduation committee); Delft University of Technology (degree granting institution)","2019","The area surveillance problem is the problem of surveying a known or an unknown area with the main purpose of detecting objects. This thesis will tackle the problem of how to employ a group of mobile-sensors for surveying an unobstructed area in an optimal manner. The mobile-sensors should make use of their onboard computers and they should iteratively compute their waypoints until they successfully surveyed the area. To solve the area surveillance problem in an optimal manner, the mobile-sensors should be able to coordinate their actions. The Distributed Constraint Optimization Problem (DCOP) framework will be employed to define the area surveillance problem. In the DCOP, the mobile-sensors can define their optimal position for the next discrete time step by communicating with the other mobile-sensors that participate in the problem.

For solving this DCOP, the Distributed Pseudo-tree Optimization Procedure (DPOP) will be utilized. The DPOP is a complete solver that can find the optimal solution of a DCOP in a decentralized manner. However, the main limitation of DPOP is that the size of the largest message that the mobile-sensors will have to exchange is space-exponential in the induced width of the pseudo-tree. Considering that the mobile-sensors have to use their onboard computers for solving the problem, exchanging huge size of messages is not desired. To overcome this limitation of DPOP, a new extension, known as the MST-DPOP will be presented in this Thesis. The MST-DPOP makes use of the Maximum Spanning Tree (MST) algorithm to reduce the size of the largest message that the mobile-sensors have to exchange. Employing MST along with DPOP can bound the size of the largest message and the required computations for constructing the utility messages. However, the new extension cannot guarantee that its solution will be the optimal. The experimental results shows that the MST-DPOP is able to define a solution with an average error less than $2\%$. Moreover, the MST-DPOP requires on average around $1$ discrete time step more than the DPOP to solve the area surveillance problem. Consequently, given that the MST-DPOP overcomes the high memory requirements of DPOP, it is preferred for solving the area surveillance problem.","Optimization; DCOP; DPOP; Decentralized coordination","en","master thesis","","","","","","","","","","","","Mechanical Engineering | Systems and Control","","" "uuid:18a163a2-98a1-438f-afc9-a66c500009ed","http://resolver.tudelft.nl/uuid:18a163a2-98a1-438f-afc9-a66c500009ed","Improvement of road traffic sustainability by implementation of priority weights for trucks in predictive signalized intersection control","Haanstra, Leroy (TU Delft Mechanical, Maritime and Materials Engineering)","Jiang, Xiaoli (mentor); Polinder, Henk (graduation committee); Taale, Henk (graduation committee); Delft University of Technology (degree granting institution)","2019","In the European Union Road freight transport volume is expected to grow 78% between 2000 and 2030, which results in more trucks on the road network. The worldwide estimated trend shows an increase of 150 million freight vehicles and an increase of 240 million passenger vehicles. The growth of both vehicle classes will have a major impact on the road network and the roads will become congested. Especially in dense urban environments with many intersections. Further, trucks have a detrimental impact on traffic flows, especially at intersections, because of their slow dynamics and large size. In addition, a stopping truck results in higher emissions and fuel consumption compared to a car. However, today’s traffic controllers are not capable of optimizing traffic flow at intersections based on classification of different vehicles. Therefore, it would be beneficial to all vehicles involved if the number of stops for trucks would be reduced to a minimum, by servicing each vehicle class in a different way.

Throughout this research the focus is to develop a signalized intersection controller which is able to reduce the number of stops for trucks, while maintaining an equal level of service for the other modes of transport. Extensive literature studies provided important insights into the development of signalized intersection controllers. A selection of the techniques found in the literature is used to develop a new truck signal priority controller design. The basic idea is to use a weighted traffic light schedule in combination with priority weights to enable truck signal priority. The design is evaluated in a case study and simulated for multiple configurations. This leads to an overview of the performance in terms of the number of stops and vehicle delay.

From the results several conclusions can be drawn on the optimal weight configuration, which is compared to a state-of-the-art model predictive intersection controller. The results showed an reduction of the total number of stops by 751 and total vehicle delay by 304 minutes for trucks over a week (26,6% and 20,4% respectively). While, the total number of stops and total vehicle delay for cars increased, by 155 stops and 201 minutes (0,1% and 0,3% respectively). However, the overall total number of stops and total vehicle delay were reduced by 596 stops and 103 minutes (0,42% and 0,16% respectively). It can be concluded that the proposed truck signal priority controller design can reduce the number of stops for trucks at a signalized intersection, while maintaining the overall traffic flow at least as good as a state-of-the-art model predictive intersection controller.","Signalized intersection controller; Truck Signal Priority; Simulation; Optimization","en","master thesis","","","","","","","","2019-05-31","","","","Transport Engineering and Logistics","","" "uuid:78792084-4158-4ba5-91e0-c88e6033a216","http://resolver.tudelft.nl/uuid:78792084-4158-4ba5-91e0-c88e6033a216","Automation of the conceptual design stage for material handling systems: Development of an automated design model for the conceptual design phase of baggage handling systems","Vijlbrief, Mark (TU Delft Mechanical, Maritime and Materials Engineering)","Beelaerts van Blokland, Wouter (mentor); Schott, Dingena (graduation committee); Delft University of Technology (degree granting institution)","2019","Baggage handling systems (BHS), are complex and integrate systems hidden within an airport. In this thesis, a model is developed which can generate BHS concept design automatically. This means that the model defines the type and amount of equipment needed and is able to develop a 3D model that can be used for volume reservation. The model takes into account the stakeholders desires, operational preferences and the terminal shape and size and can therefore define the optimal solution for the stakeholders. By developing this model, a generalized design framework for material handling systems in general can be created,","Baggage Handling System; Automation of design; Generative Design; Optimization; Material handling systems","en","master thesis","","","","","","","","2024-03-07","","","","Transport Engineering and Logistics","","" "uuid:51377918-74be-4ec4-bad2-115276e35cd8","http://resolver.tudelft.nl/uuid:51377918-74be-4ec4-bad2-115276e35cd8","Tensegrity Full Body Control: An Inequality Constrained Optimization Approach","Gudmundsson, Kjartan (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Biomechanical Engineering)","van der Weijde, Joost (mentor); Vallery, Heike (graduation committee); Peternel, Luka (graduation committee); Delft University of Technology (degree granting institution)","2019","Tensegrity is a structural form that is defined as a set of rigid elements suspended in a net of continuous tension. This structure shows potential for compliance, impact tolerance and mechanical robustness. However, its non-linear coupled dynamics and often complex geometry require advanced control strategies. An actuator reference planning strategy to bring tensegrity robots closer to controlled full body movements was proposed by Guido Tournois \cite{GuidoThesis} in 2017. This strategy, called the Full Body Reference Planner (FBRP), finds a sequence of equilibrium configurations for a tensegrity structure, predominantly to follow a trajectory in space. However, the method is incapable of incorporating inequality constraints while obtaining said equilibrium configurations. This is a problem when dealing with certain restrictions, e.g., actuator limitations and stability of the structure.

In this thesis we implemented a robust way to account for inequality constraints while utilizing the FBRP. That was done by means of optimization, i.e., an implementation of a Sequential Quadratic Programming method to ensure inequality constraints were respected for each configuration. The approach was validated in scenarios related to practical applications where inequality constraints were enforced. The results showed advancements towards practical feasibility. Furthermore, the robustness, efficiency and accuracy of the method were validated. The extended implementation depicted robustness to parameter variations and good results in terms of accuracy. However, given the iterative nature of the method, it was more computationally expensive than its precursor.","Tensegrity; Robotics; Optimization","en","master thesis","","","","","","","","","","","","Mechanical Engineering","","" "uuid:66aaf067-8763-4c39-91e3-ef01fb25948d","http://resolver.tudelft.nl/uuid:66aaf067-8763-4c39-91e3-ef01fb25948d","Optimization of Composite Structures for Crashworthiness","Li, Ang (TU Delft Aerospace Engineering)","Bisagni, Chiara (mentor); Delft University of Technology (degree granting institution)","2019","Structural optimization for crashworthiness in composite structures has become an important topic of research in aerospace, attributable to its proven benefits to the occupants' safety in an aircraft during a crash event. This thesis provides a comprehensive investigation on LS-DYNA modeling and design optimization of composite square tubes for crashworthiness. The objective of this thesis is to construct a optimization framework specialized for the preliminary design of composite structures with a balance of performance and efficiency. Three primary components are involved: firstly, coupon-level simulations in LS-DYNA are performed to characterize the material properties for carbon/epoxy composite material IM7/8552; secondly, a square tube is modeled by a single-layer approach in three mainstream material cards (MAT-54, MAT-58 and MAT-262) with calibrated parameters for crush simulation in LS-DYNA. Meanwhile, detailed sensitivity analysis of influential parameters in different material models is also be performed to have a more comprehensive understanding of the complex failure mechanism. The simulation results indicate good correlation to the experiments in terms of energy absorption and maximum peak load, with high computational efficiency and low-cost calibration. Lastly, a two-stage single-objective optimization is performed, which incorporates the fiber orientation for each layer as design variables and design/manufacturing rules as constraints. Two surrogate models are created to formulate the mapping between input design variables and output crashworthiness metrics, including Deep Neural Networks (DNN) and Gradient Boosting Regression Trees (GBRT) ensemble. Followed by Mix-Discrete Particle Swarm Optimization (MDPSO) algorithm, the optimal set of design variables are obtained for each surrogate model. The first-stage optimization results demonstrate significant improvement in the crashworthiness performance compared with the baseline value, while the second-stage optimization results indicate an excellent transferability of the proposed optimization framework. This applicable, transferable, and data-driven optimization framework can be used in the aerospace industry regarding the crashworthy design and optimization of composite structures.","Optimization; Crashworthiness; Surrogate models; LS-DYNA","en","master thesis","","","","","","","","","","","","Aerospace Engineering","","51.9900, 4.3754" "uuid:61a8031c-9278-494d-8892-0fc4c8252b84","http://resolver.tudelft.nl/uuid:61a8031c-9278-494d-8892-0fc4c8252b84","Developing a parametric script for the preliminary design and optimization of concrete balanced cantilever bridges","Scheele, Bram (TU Delft Civil Engineering and Geosciences)","Nijsse, Rob (graduation committee); Jonkers, Henk (graduation committee); van der Linden, Lennert (graduation committee); van der Sanden, Janine (mentor); Delft University of Technology (degree granting institution)","2019","In this thesis, research is performed into parametric design of balanced cantilever bridges within the total road design. The main research question is: What can be achieved by using a parametric model in the preliminary design phase, with the possibility to optimize and compare concrete bridges on material usage, costs and environmental impact? And to answer this question, the cantilever bridge and all other elements in the road design are investigated and a parametric model is developed. In this model the total vertical alignment of the road design is implemented along with approach bridges, substructure and foundations. Furthermore, the results of the designs are visualized in a 3D environment compared with an overview of the material costs and environmental impact. In the ""Discussion"", the following is concluded: Although the parametric model for the preliminary design of concrete cantilever bridges took a long time to develop, this time investment can be regained by using the model several times. Because by using the parametric model for the preliminary design of concrete bridges, the design time per procurement is decreased significantly. Furthermore, the design process of the balanced cantilever bridge has become more flexible since changes are automatically implemented for the whole model. Also the chance for (human) errors is decreased, for instance the risk of data loss is minimized due to the model’s single environment. Since only a limited amount of calculations is performed by the model, the results of the analysis must be used with caution. Another advantage is the instant results as produced by the model. These results consist of a visualization of the design and an overview of the material amounts, with their costs and environmental impact. Furthermore, the model is also able to optimize these results in a fast way due to a smart evolutionary solver. This all together makes the parametric model a useful tool with high potential, but it should be further

developed and improved.","Parametric design; Concrete; Bridge; cantilever; Materials; Costs; Optimization; Grasshopper","en","master thesis","","","","","","","","2020-02-19","","","","Civil Engineering","","" "uuid:621c77c4-6764-4d17-9a0a-b3d3dd3025e0","http://resolver.tudelft.nl/uuid:621c77c4-6764-4d17-9a0a-b3d3dd3025e0","Guidance and Control for Spinning, Gun-Launched Projectiles","van der Geest, Lars (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Delft Center for Systems and Control)","van Wingerden, Jan-Willem (mentor); Bouquet, François (mentor); Hellendoorn, Hans (graduation committee); Keijzer, Twan (graduation committee); Delft University of Technology (degree granting institution)","2019","This thesis report is focused on the design of a guidance and control system that is able to minimize the deviation from the desired impact point for a firing range of 1 kilometer, given a 30mm spinning gun-launched projectile with a novel actuator design. This actuator is fixed on the projectile and offers a single force that can only be switched on or off.

In order to test the effectiveness of the guidance, navigation and control (GNC) system, an accurate model for both the projectile and the proposed actuator are constructed. These models will serve as a substitute for testing with working prototypes. The model for the projectile dynamics is constructed based on existing nonlinear 6-DOF rigid-body models that are widely-used and validated. A new, simplified second order model that approximates the dynamics of the actuator, based on available measurements, is constructed.

The overall structure of the GNC loop is defined, with the guidance method of choice being the pre-calculation of a reference trajectory towards the intended target. This method serves to alleviate under-actuation and computation time problems. One of the most important contributions of the thesis is made with the description of a method for transforming the input from a single binary input signal towards two continuous virtual input forces. This method uses a discretization of the rolling motion of the projectile, such that an optimization can be done which results in a transformation from the binary on/off signal to two virtual force inputs. These two virtual force represent the steering forces in the directions perpendicular to the forwards motion that would have the same effect as the binary on/off signal if directly applied on the projectile.

The restructuring of the input allows for the use of PD-controllers to track the pre-defined trajectory. Using a grid-search method, the controller gains are found that best satisfy the design goal of minimizing the dispersion, which is defined by the sum of the mean error and the standard deviation of the impact points.

Analysis of the integrated solution shows that the proposed solution with the input transformation and the PD-controller is able to significantly reduce the projectile dispersion from standard deviations of about 50 cm to just a few cm. The exact performance depends on the frequency of the actuator and the spin rate of the projectile. The best performance is reached with high spin rates and actuator frequencies high enough to match these spin rates.","Guidance; Control; Projectile; PD control; Optimization","en","master thesis","","","","","","","","2024-02-21","","","","Systems and Control","","" "uuid:068ff836-099b-4abe-8d9e-cf96706169df","http://resolver.tudelft.nl/uuid:068ff836-099b-4abe-8d9e-cf96706169df","Classifying Candida species using Mixed Integer Optimization based optimal classification trees","van Dijk, Mick (TU Delft Electrical Engineering, Mathematics and Computer Science)","van Iersel, Leo (mentor); Stougie, Prof. dr. L. (mentor); Kelk, Steven (mentor); Boekhout, Prof. dr. T. (graduation committee); Aardal, Karen (graduation committee); Delft University of Technology (degree granting institution)","2019","Global medical use of azole antifungals and echinocandins has led to an enormous increase in resistant

Keeping in view the high velocities that are obtained in the channels of the cooling system of the target assembly, an extensive 3D turbulence modeling of the full scale cooling system is required in order to predict the target water cooling system behavior. A comparative conjugate heat transfer (CHT) study using a simplified 2D geometry of the BDF target for different mesh size was performed for identical y+ values to validate the pressure drop in the cooling channels and the temperature profile in the target blocks with the analytical calculations. Subsequently, a 3D model of the cooling channel was simulated for different Reynolds number and an extensive study was performed to check the behaviour of the flow in the log-law layer. In addition to that the friction factor was validated with the analytical results and with the available literature for various Reynolds number. Thereafter a full scale 3D steady and transient model was simulated using the information obtained from the previous studies. All these simulations were carried out in Ansys Fluent. The energy deposition in space on the target blocks was obtained via FLUKA MonteCarlo simulations. The variation of HTC in different channels and the fluid-solid interface temperature is found out to be in accordance with the analytical calculations. The pressure drop and the temperature rise from inlet to outlet of the cooling system is also in confirmation with the design parameters. Transient simulations were performed subsequently in order to study the impact of time and space varying energy deposition in the target blocks on the overall flow. With the given inlet velocity, the boiling at the surface of the target blocks is not expected to happen. As a final part of this study, in order to make the numerical model more robust, a mesh sensitivity analysis was done in order to optimize the mesh size, especially in the boundary layer region.","Beam Dump Facility; Target; SHiP; SPS; Turbulence Modelling; Conjugate Heat Transfer; FLUKA; Fluent; CERN; Cooling system; Optimization","en","master thesis","","","","","","","","2018-12-19","","","","Mechanical Engineering | Energy and Process Technology","Beam Dump Facility | SHiP | Physics Beyond Particles","" "uuid:3378e0cf-7831-4432-a383-c9c5c8dbce2d","http://resolver.tudelft.nl/uuid:3378e0cf-7831-4432-a383-c9c5c8dbce2d","Co-orbital motion and its application to JAXA's MMX mission","Bernal Mencia, Pablo (TU Delft Aerospace Engineering)","Noomen, Ron (mentor); Kawakatsu, Yasuhiro (mentor); Delft University of Technology (degree granting institution)","2018","In the framework of JAXA's MMX mission to explore the Martian moon of Phobos, an analysis of the stability of three-dimensional quasi-satellite orbits in the Mars-Phobos circular restricted three-body problem was conducted. For this analysis, notions of co-orbital motion, interpreted as the slow motion of the guiding center of the trajectory along the disturbing potential of Phobos, were used. After identifying and analyzing different regions of stability for three quasi-satellite orbits at 100, 50 and 30 km from the center of Phobos, several conclusions were drawn regarding the dynamics of the ballistic escape of the spacecraft, interpreted in terms of co-orbital motion. By making use of these insights, a novel methodology to find periodic quasi-satellite orbits able to reach high latitudes over the surface of Phobos was derived. This methodology consists of two steps: a multi-objective minimization using co-orbital parameters as target functions, to isolate regions with potential periodic orbits; followed by a shooting algorithm to arrive at the final periodic orbit. As a result of this new methodology, two periodic orbits were found at 50 and 30 km from the center of Phobos, able to reach latitudes as high as 54 deg and 32 deg respectively. This result represents an important contribution to both the operations and the scientific return of the Phobos proximity phase within MMX.","Astrodynamics; Orbit Design; Optimization; Multi-objective optimization; Periodic Orbits; Mars; Python","en","master thesis","","","","","","","","2020-01-01","","","","Aerospace Engineering","","" "uuid:c5ddec13-e103-49b4-8b84-a8ad013c753c","http://resolver.tudelft.nl/uuid:c5ddec13-e103-49b4-8b84-a8ad013c753c","Multi-fidelity Co-Kriging Optimization using Hybrid Injected RANS and LES","Fatou Gomez, Javier (TU Delft Aerospace Engineering)","Hickel, Stefan (mentor); Dwight, Richard (mentor); Delft University of Technology (degree granting institution)","2018","The computation of complex turbulent flows design optimization processes is currently limited by the lack of accuracy of Reynolds-Averaged Navier-Stokes (RANS) in massively separated flows and the infeasible cost of multiple Large-Eddy Simulation (LES) evaluations. A novel method is presented, injecting data from LES or other high-fidelity source such as DNS into the RANS equations, forming a Hybrid Injected RANS (HIRANS) model. The aim is to construct a multi-fidelity design optimization framework that outperforms single-fidelity RANS and LES variants. Two different formulations, injecting a scaled version of the non-dimensional anisotropic part of the Reynolds stress tensor and both isotropic and anisotropic components, are tested in the periodic hill case. A cost-effective LES configuration is assessed, and the agreement of the RANS and HIRANS results with respect to the LES reference is investigated. The original geometry is parametrized using a hill width multiplier, computing several LES evaluations. The injection of LES information from the same geometry into HIRANS and the prediction capabilities when using interpolated data from different geometries are tested. A global design optimization process is computed, using single-fidelity RANS, HIRANS and LES Kriging and multi-fidelity RANS-LES and HIRANS-LES Co-Kriging surrogates. The objective function is based on a combination of turbulent mixing and total pressure losses.

The correction of the mean velocity components required of the injection of both isotropic and anisotropic components for the test case. The LES setup analysis yielded similar results to the reference data with one tenth of grid points and forty percent of its averaging period. The locally corrected HIRANS model successfully reduced the L2 norms of the Reynolds stresses with respect to LES to a third part of the original RANS values in the fifty-nine LES samples tested, with a modest improvement in the mean velocity components. The non-local corrections yielded irregular results for the mean velocity components, with successful corrections of the Reynolds stresses despite the long distances in the parameter space and different flow features of neighbouring LES cases to interpolate from. In the optimization process, the Co-Kriging LES-HIRANS was not able to outperform the Co-Kriging LES-HIRANS and Kriging LES methods. It improved the initial prediction of the underlying function, but the surrogate yielded artificially low predicted errors far away from the LES samples, leading to an overly exploitative method. An error correction formulation combining two HIRANS fidelity levels was simulated using a modified Kriging believer criterion, outperforming the original formulation and achieving similar results as Kriging LES. The computational efficiency improvements for future research of the Co-Kriging HIRANS are suggested to be linked to an adequate error estimation integration into the surrogate model.","RANS; LES; HIRANS; Turbulence; CFD; Interpolation; Optimization; Kriging; Co-Kriging; Aerodynamics; Periodic hill; Correction; Prediction","en","master thesis","","","","","","","","2018-12-14","","","","Aerospace Engineering","","" "uuid:841a9a8d-c7d4-4bdb-a1a4-7a4e7960070b","http://resolver.tudelft.nl/uuid:841a9a8d-c7d4-4bdb-a1a4-7a4e7960070b","Continuous-time System Identification: A Bilinear Optimization Approach","Krijgsman, Wiegert (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Delft Center for Systems and Control)","Verhaegen, Michel (mentor); Doelman, Reinier (mentor); Delft University of Technology (degree granting institution)","2018","In the noiseless case, the identification of a grey-box model can be posed as a feasibility problem, i.e. determining if existent - and if so - finding a parameter vector such that the parametric model equals the actual model (or its associated input-output data). Being that in this thesis we are interested in continuous-time grey-box identification, we shall be dealing with models that allow for forming a direct relationship with physical meaningful quantities. Such models include the state space representation and the matrix differential equation. In general, identifying such grey-box models turns out to be a non-convex problem. In this thesis, we initially review a framework which allows us to solve feasibility problems which have bilinear constraints. It turns out that most of the aforementioned non-convexities can be captured into a single bilinear matrix equation. However, the resulting feasibility problem, including the bilinear matrix equations, makes the overall search for the actual parameter vector NP-hard. In order to come up with numerical tractable algorithms, we use a heuristic known as Sequential Convex Relaxation to relax the bilinear equality constraints. This iterative scheme is flexible enough to allow for additional (in)equality constraints, possibly resembling any other physical constraints. We explore two different approaches to identify both the state space model and the matrix differential equation; one, by directly identifying the model from the given frequency response function; two, by first identifying a black-box model before performing a small scale optimization problem, transforming the black-box model such that it fits the grey-box parameterization. In addition, we present a novel method which uses the Power Spectral Density to estimate a 2nd order model. All methods are numerically validated.

A modular simulation environment is designed using the TU Delft Astrodynamics Toolbox to simulate the atmospheric trajectory of the aerogravity assist. This simulator allows the selection of different types of acceleration and environment models. The waverider is selected to be the vehicle used during the aerogravity assist, as it is able to obtain high lift-over-drag ratios which reduce the drag losses during the atmospheric section of the maneuver. The specific aerodynamic characteristics and heating models of the selected vehicle are evaluated and incorporated into the simulator. From this simulation environment, the optimal atmospheric trajectories were investigated using an optimization algorithm. It was found that this specific problem is extremely sensitive to the selected optimization algorithm, the tuning parameters of the optimization algorithm, and the objecive and decision variables that are used. The MOEA/D algorithm was selected to find the optimal atmospheric trajectories for Mars, Earth, and Venus, where the objective variables were chosen to be the atmospheric bending angle and the incoming and out-going inclination difference. It was found that using the angle-of-attack and bank angle as control variables, an atmospheric bending angle of 120.5 degrees and an inclination difference of 0.2 degrees could be obtained at Mars. Using the control action instead of the inclination difference as objective variable at Mars showed that the atmospheric bending could be increased to 151.2 degrees while maintaining an inclination difference of below 3 degrees, and smoothed the trajectory in the process. For Earth and Venus the same optimization scheme was employed. They were able to obtain atmospheric bending angles between 70 and 50 degrees, while obtaining inclination differences below 1.5 degrees. For Venus, the heat load was also optimized instead of the inclination difference and it was found that the peak heat flux decreased by around 1000 W/cm$^2$, while decreasing the atmospheric bending angle by around 10 degrees.

A mission planner was designed to be able to investigate the effect of the aerogravity assist on interplanetary trajectories. To increase the accuracy of this mission planner, the numerically found atmospheric trajectories are used to determine the possible interplanetary trajectories. Pareto fronts were created for Mars, Earth, and Venus for a range of incoming velocities that showed the possible velocity bending angles and out-going velocities that can be achieved using an aerogravity assist. These Pareto fronts were then implemented in the mission planner to determine the influence of the AGA on an interplanetary trajectory. Several different interplanetary trajectories were investigated using both gravity and aerogravity assists. It was found that due to the fact that for Earth and Venus higher velocities are needed to travel through the atmosphere, the aerogravity assist would lose too much velocity and thus not improve upon the gravity assist. However, for Mars an increase was found of 4 km/s compared to the gravity assist for a trajectory to Saturn using fly-by's at Mars and Jupiter. Taking into account the extra mass of the thermal protection system, the decrease of mass was found to be around 60 percent, which could be used to lower the cost of the launcher or increase the scientific output of the mission by adding instruments to the payload.

This study proposes optimization strategy for optimal battery sizing and placement with optimal power management system in the EVs charging station using photovoltaics (PV) power in a low voltage distribution network using Mixed Integer Linear Programming (MINLP) algorithm. The lithium-ion battery is considered in this project because of its relatively high power and energy density characteristic along with low self-discharging. The radial low voltage CIGRE benchmark is adopted as a model topology to evaluate the performance of the proposed optimization strategy. Dynamic daily electricity price, residential load, and PV power profile of the Netherlands are taken into account in this project. Furthermore, the research project implements several case studies using DICOPT (Discrete and Continuous OPTimizer) solver in GAMS (General Algebraic Modelling System) software with MATLAB interfacing. As the main result, proper EVs charging strategy with optimal battery sizing and placement with the appropriate power management system is successfully maintaining the system away from the grid violation while at the same time reducing the total cost of the system.

Keywords: EV-PV charging, optimal battery sizing and placement, MINLP

An inventory of different objective functions is prepared, and relevant ones are selected for further study. It is observed that even though some objectives are dissimilar, they still depend on the same wind farm parameters and are therefore expected to give similar design results. From the list of objective functions, net present value (NPV) and risk management objectives are chosen for further research.

The selected objective functions are then formulated in a metric for optimization. The price of electricity plays a significant role in determining the NPV. It is learnt that electricity price varies with the power supply depending on the site conditions. The electricity price is low if the supply of power is high in a region where there are many OWF’s and vice versa. Moreover, OWF investors value constant power output without any fluctuations. Hence, taking all these aspects into consideration, the electricity price in the NPV function is modelled for a constant value, wind variability and wind power predictability.

The risk management function, on the other hand, aims at minimizing the uncertainty associated with an OWF project. The risk here refers to the uncertainty associated with the profit obtained from the OWF. A set of annual average wind speeds is computed using monte carlo simulations and the AEP and NPV are estimated. The mean( NPV_mean) and standard deviation ( NPV_std ) of NPV are then calculated. NPV_std represents the uncertainty in this scenario and is minimized to reduce the risk.

A suitable method is then identified to deal with multiple objectives. The NPV function is maximized for maximum profit and this objective is evaluated using a single objective optimization technique. The risk management objective involves the calculation of NPV_mean and NPV_std. Both objectives are contrasting in nature as a significant reduction in NPV_std corresponds to an undesirable reduction in NPV_mean. A tradeoff between both these objectives is the best possible solution. Therefore, a multi- objective optimization technique is used, and a list of solutions is obtained by generating a pareto front.

The new approach is then evaluated by implementing different case studies. It is observed that optimum rotor diameter and number of turbines for the single objective optimization technique are influenced by economic indicators such as the real interest rate and lifetime. However, they are not influenced by variation in the electricity price. Nevertheless, the NPV function is sensitive to the economic indicators and variation in the electricity price.

For the multi - objective optimization technique, multi criteria analysis was used to determine the weight to the objective functions while moving along the pareto curve. It was observed that the improvement of one objective led to the deterioration of the other objective. Hence, the pareto front provides opportunities to investors to negotiate and decide on the weight they want to specify for their objectives.

The research covers the optimization process of a motion compensated gangway. A motion compensated gangway is a walkway which can be used to provide access from the transport vessel to the offshore structure. Its function is to transport people and cargo safely from the ship to the offshore structure or vice

versa. The goal of this research was to determine to what extent topology optimization can be used in the design of a motion compensated gangway. Finding an optimized result in terms of weight and stiffness by using this mathematical method which satisfies all the requirements. The structural optimization is carried out with several commercial software packages which are compared by using a multi-criteria analysis.

During the optimization process it has been found that there are essentially two stages in the optimization process. In the first stage, the topology or beam orientation of the structure is defined by the topology optimization process. In this part the concept of the design is generated. Variation of the optimization parameters was used in order to develop an efficient structure. The objective for the optimizer was to minimize the compliance of the structure for a certain volume fraction.

In the second stage, the dimensions of all the beams and elements are defined by performing a size optimization. A line model is generated which represents the orientation of the members in the structure. During the size optimization the shape and the dimensions of the members are defined in order to fulfill the

objective. The objective is to minimize the mass of the structure while constraints are defined for the maximum allowable stresses in the members and the maximum vertical deflection of the structure. This post-processing step is required in order to obtain a feasible design. The structural stability of the gangway was improved by performing a linear buckling analysis and by adapting the structure in order to reduce the buckling behaviour.

In the final step of the optimization process, a CAD drawing is generated. This model is analysed by performing a finite element analysis. This showed that the new optimized design satisfies all the requirements which are stated by the DNV for designing a motion compensated gangway. The combination of the topology and size optimization resulted in a new design which yielded a weight reduction of 36,4% compared to the current design. The weight was reduced from 13,08 ton to 8,31 ton, while still satisfying all the constraints. Therefore it can be concluded that this methodology can be used in the optimization of a motion compensated gangway structure","Optimization; Topology optimization; Shape optimization; Motion compensated gangway; Structural Optimization; Optistruct; Hyperworks; Size optimization; Design methodology","en","master thesis","","","","","","","","2020-10-09","","","","Offshore and Dredging Engineering","","" "uuid:71ec065f-cec0-4b67-a8cd-90882c3a86a7","http://resolver.tudelft.nl/uuid:71ec065f-cec0-4b67-a8cd-90882c3a86a7","Evaluating cooperation policies for rail utilization in the port to hinterland freight transport system: A combined method approach","Karampelas, Dimitrios (TU Delft Civil Engineering and Geosciences)","Tavasszy, Lóri (mentor); Maknoon, Yousef (mentor); Duinkerken, Mark (mentor); Kourounioti, Ioanna (mentor); Delft University of Technology (degree granting institution)","2018","As the margins for improvements in the current freight transport system become limited, researchers address more and more the importance of collaboration between the actors which is crucial for the implementation of new, more efficient transport concepts as synchromodality. In addition, rail is concerned as a sustainable mode of transport that can also achieve economies of scale due to its ability to haul large quantities of goods. This study investigates cooperation policies that affect actors’ behavior to better utilize the rail use and lead to a more efficient system. We propose an innovative approach that combines gaming, simulation and optimization as a mixed method to test and evaluate these policies. The port to hinterland freight transportation system in the range of Port of Rotterdam is used as a case study. First, gaming sessions are organized in order to observe actors’ behavior and collect data. The game that is used was initiated by Port of Rotterdam, especially to identify the problems in this system. Subsequently, by assessing the observed data, a simulation model is developed and different policy scenarios are simulated to quantify their performance. In addition, the optimization model is developed, which sets the upper bound for performance and used as a solid base for comparison between the policy alternatives. Finally, the explanation of the difference between the policies’ and the optimized performance can give an insight on what are the root causes of the inefficiency, what is the best allocation of the resources and where the solutions should be focused.","cooperation; Policies; Collaboration; Freight Transport; Port; hinterland; gaming; simulation; Optimization","en","master thesis","","","","","","","","","","","","Transport, Infrastructure and Logistics","","" "uuid:04f50f3b-8572-4c68-b75b-e6990c639be0","http://resolver.tudelft.nl/uuid:04f50f3b-8572-4c68-b75b-e6990c639be0","Design and Implementation of a Development Platform for Indoor Quadrotor Flight Control","Navia Vela, Libardo (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Delft Center for Systems and Control)","Keviczky, Tamas (mentor); Zheng, Zixuan (mentor); Delft University of Technology (degree granting institution)","2018","Research and development of flight control of quadrotor Unmanned Aerial Vehicles (UAVs) have gained popularity during the past few years due to their deployment flexibility and wide range of applications: agriculture, entertainment, cinematography, package delivery, search and rescue, etc. This thesis project follows up this interest aiming to build a real-time development platform for experimentation and test of indoor flight controllers in the Networked Embedded Robotics in Delft laboratory. For this goal, we employ a Matrice 100 quadrotor from DJI alongside its ROS C++ Software Development Kit (SDK), develop a system identification routine to model its autopilot, vertical and horizontal displacement, and based on the attained results, we design and implement a control topology for real-time position control of the UAV inside the laboratory by means of a Model Predictive Controller (MPC) and a Linear-Quadratic Regulator. Finally, we enunciate and discuss potential applications in which this development platform can be used.","UAV; MPC; Optimization; ROS; C++; LQR; Quadrotor","en","master thesis","","","","","","","","","","","","Systems and Control","","" "uuid:dec3c264-d652-4370-864c-1f9ea18cbd2a","http://resolver.tudelft.nl/uuid:dec3c264-d652-4370-864c-1f9ea18cbd2a","Reservoir Characterization using a Geometric Approach","Khandelwal, Anshul (TU Delft Electrical Engineering, Mathematics and Computer Science)","Eisemann, Elmar (mentor); Hildebrandt, Klaus (mentor); van de Giesen, Nick (graduation committee); Liem, Cynthia (graduation committee); Delft University of Technology (degree granting institution)","2018","Quantifying the anthropogenic impacts such as reservoir characterization is a big challenge in the field of water management. In this work, a computer graphics based geometric approach is presented which can predict the underlying topology of large-scale reservoirs. The proposed algorithm uses freely available, satellite based landscape data of the surrounding regions to predict reservoir characteristics. The premise of the presented approach is that the slope of the surrounding landscape is an important determinant to understand the underlying landscape of the reservoirs. This method outperforms the existing state-of-the-art techniques used to estimate the storage capacities drastically, both in terms of estimated maximum volume stored and estimated volume area curves. Evaluation of the geometric model presented is done on 28 reservoirs using the HydroSHEDs data which was developed using the Shuttle RADAR Topography Mission conducted by NASA. This HydroSHEDs data was obtained in 2000 which acts as ground truth data for the reservoirs built after 2000. Further, model parameters are introduced to improve the modeling capabilities of the reconstructed reservoirs. This approach further intensifies the case of using computer graphics techniques for raster based analysis and provides a platform for further research in the field of water management.

We use the Space Time Network (STN), in which the travel time of modalities is fixed and independent of the occupancy of the network.

We define the User Equilibrium solution as the solution wherein each customer can travel via their cheapest paths possible, and no customer is harmed by the route choice of other customers. We define the System Optimal (SO) solution as the solution in which the total costs of the network are minimized.

We expand the goal of finding a UE on the STN to finding a solution where the solution is both SO as well as UE.

The solving method we developed in this thesis, consists of finding SO solutions by solving the Minimum Cost Multi-Commodity Flow (MCMCF) problem on the STN to find an SO solution, and create tolls schemes to create a UE solution, while maintaining the SO solution.

We investigate several types of tolls in order to obtain sufficient both SO and UE solutions.","Optimization; User Equilibrium; Toll Pricing","en","master thesis","","","","","","","","","","","","Applied Mathematics","","" "uuid:f2e84a4a-aef4-45b5-a9d0-e97afd17b04b","http://resolver.tudelft.nl/uuid:f2e84a4a-aef4-45b5-a9d0-e97afd17b04b","A robust optimization approach to synchromodal container transportation","Chiscop, Irina (TU Delft Electrical Engineering, Mathematics and Computer Science)","De Klerk, Etienne (mentor); Phillipson, F. (graduation committee); Sangers, A (graduation committee); Nane, Tina (graduation committee); Delft University of Technology (degree granting institution)","2018","This thesis addresses synchromodal planning at operational level from the perspective of a logistics service provider. The existing infrastructure and the transportation activities are studied and modeled as an optimization problem with simultaneous vehicle routing and container-to-mode assignment. A special characteristic of this problem is the uncertain data. In other words, it is assumed that the release times of the containers belong to an uncertainty interval, and no further statistical information is available. The problem is then classified according to an extensive framework previously developed within the project. An extensive body of literature is reviewed to identify current modeling approaches and their theoretical and practical limitations. This literature study shows that, although discrete time models have been intensively investigated, there are few studies which propose continuous modeling of time. The container routing problem is modeled as a mixed integer program with explicit time variables and lateness penalties. A robust formulation is then proposed to eliminate the uncertain parameters from the objective function and constraints. By solving the new model exactly, with the aid of an optimization solver, robust solutions are obtained corresponding to transportation plans which remain feasible for any realization of the release times within the pre-specified uncertainty interval. In order to introduce some flexibility in the transportation plan, the continuous time variables are modeled as affine functions of the uncertain parameters. The resulting two-stage decision model is tested for a small-sized instance in both situations, with high and low lateness penalties. The computational results show that the adjustable robust model yields on the one hand, route-dependent adjusted solutions for the case of penalized lateness, and on the other hand, a direct improvement of the objective function for the case of tolerated lateness. The results suggest that the adjustable robust optimization framework has sufficient potential to model the synchromodal container routing problem. This thesis concludes with addressing some of the limitations of the proposed model and indicating concrete approaches for countering them.","Synchromodal; Robust; Optimization","en","master thesis","","","","","","","","","","","","","","" "uuid:c6924adf-9f7b-4850-8099-056eb06bc11a","http://resolver.tudelft.nl/uuid:c6924adf-9f7b-4850-8099-056eb06bc11a","Optimization Strategies of CO2 Injection for Sequestration and EOR","Chen, Yuan (TU Delft Civil Engineering and Geosciences)","Voskov, Denis (mentor); Delft University of Technology (degree granting institution)","2018","The current situation with green gas emission requires the development of low carbon energy solutions. However, a significant part of the modern energy industry still relies on fossil fuels. To combine these two contradictory targets, we investigate a strategy based on a combination of CO2 sequestration with Enhanced Oil Recovery (EOR) in the hydrocarbon reservoirs. In such technology, the development of miscibility is the most attractive strategy from both technological and economic aspects.

Modeling of this process involves solving complex nonlinear problem describing compositional flow and transport in highly heterogeneous porous media. An accurate capture of the miscibility development usually requires an extensive number of components to be present in the compositional problem which makes simulation run-time prohibitive for optimization. Here, we apply a multi-scale reconstructing of compositional transport to the optimization of CO2 injection. In this approach, a restriction operator, based on the parametrization of injection and production tie-lines, is constructed following the fractional flow theory. This operator is tabulated as a function of pressure and pseudo-composition which then is used in the Operator-Based Linearization (OBL) framework for simulation. As a result, a pseudo two-component solution of the multidimensional problem will match the position of trailing and leading shocks of the original problem which helps to accurately predict phase distribution. Applying a simple prolongation operator, based on interpolation between injection and production compositions, a compositional solution with the correct reconstruction of two-phase region can be obtained.

The reconstructed multicomponent solution can be used then as an effective proxy-model mimicking the behavior of the original multicomponent system. In this study, we use this proxy-model in the optimization procedure which helps to improve the performance of the simulation with the increasing intricacy of the reservoir model. In this work, the nonlinear constrained optimization function is applied to find optimal pressure values for CO2 injection process to acquire a highest Net Present Values (NPV). Starting with the limited number of the controls, the global extrema of the objective function can be determined from both full physics model and proxy model. The result shows that both models can converge to the similar extrema given various initial guesses. It is noting that for multicomponent system, the proxy model can also have salient accuracy to predict the NPV extrema compared with the original full model.

As a result, the reconstructed proxy model can be significantly cheaper than a full conventional compositional model. An additional benefit of the proposed methodology is based on the fact that important technological features of CO2 injection process can be captured with lower degrees of freedom which accelerates the optimization process.","CO2 injection; Optimization; Compositional modeling; Enhanced Oil Recovery; Carbon capture and storage","en","master thesis","","","","","","","","","","","","Applied Earth Sciences","","" "uuid:ae23df66-46bd-4946-ba9c-1364996fde4b","http://resolver.tudelft.nl/uuid:ae23df66-46bd-4946-ba9c-1364996fde4b","Modeling stochastic behavior of state variables within the optimization of departure procedures","Smits, Tommy (TU Delft Aerospace Engineering)","Hartjes, Sander (mentor); Mitici, Mihaela (mentor); Delft University of Technology (degree granting institution)","2018","","Optimization; Stochastic Analysis; Noise; Trajectory","en","master thesis","","","","","","","","","","","","Aerospace Engineering","","" "uuid:34ce9384-9352-41bc-99ce-2a54bd1f3361","http://resolver.tudelft.nl/uuid:34ce9384-9352-41bc-99ce-2a54bd1f3361","Informative Path Planning for Search and Rescue using a UAV","Anil Meera, Ajith (TU Delft Mechanical, Maritime and Materials Engineering)","Siegwart, Roland (mentor); Wisse, Martijn (mentor); Popović, Marija (mentor); Millane, Alexander (mentor); Pan, Wei (graduation committee); Alonso Mora, Javier (graduation committee); Mohajerin Esfahani, Peyman (graduation committee); Delft University of Technology (degree granting institution); ETH Zürich (degree granting institution)","2018","Target search in an obstacle filled environment is a practically relevant challenge in robotics that has a huge impact in the society. The wide range of applications include searching for victims in a search and rescue operation, detecting weeds in precision agriculture, patrolling borders for military and navy, automated census of endangered species in a forest etc. An efficient target search algorithm provides a data acquisition platform with least human intervention, thus improving the quality of life of humans. This thesis aims at introducing a general path planning algorithm for UAVs flying at different heights in an obstacle filled environment, searching for targets in the ground field. An adaptive informative path planning (IPP) algorithm is introduced that simultaneously trade off between area coverage, field of view, height dependent sensor performance and obstacle avoidance. It plans under uncertainties in the sensor measurements at varying heights, and is robust against wrong target detections. It generates an optimal fixed horizon plan in the form of a 3D minimum-snap trajectory that maximizes the information gain in minimum flight time by providing maximum area coverage, without any collision with the obstacles. The resulting planner is modular in terms of the mapping strategy, environment complexity, different target, changes in the sensor model and optimizer used. The planner is tested against varying environmental complexities, demonstrating its capability in handling a wide range of possible environments. The planner outperforms other planners like non-adaptive IPP planner, coverage planner and random sampling planner, by demonstrating the fastest decrease in map error while flying for a fixed time budget. A proof of concept for the algorithm is provided through real experiments by running the algorithm on a UAV flying inside a lab environment, searching for targets lying on the ground. All the targets were successfully found and mapped by the algorithm, demonstrating its applicability in a real-life target search problem.","Path Planning; Robotics; Unmanned Aerial Vehicle; Computer Vision; Optimization","en","master thesis","","","","","","","","","","","","Mechanical Engineering | Biorobotics","","" "uuid:13e18988-9b50-4cc8-bf8e-392455acfb44","http://resolver.tudelft.nl/uuid:13e18988-9b50-4cc8-bf8e-392455acfb44","Optimal Power Management System of EVs Charging from PV System in a Low Voltage Distribution Network: An integration between EVs, PV system and grid","Shiddiq Sumitro, Muhammad (TU Delft Electrical Engineering, Mathematics and Computer Science; TU Delft Electrical Sustainable Energy)","Bauer, Pavol (mentor); Chandra Mouli, Gautham Ram (mentor); Izadkhast, Seyedmahdi (mentor); Smets, Arno (graduation committee); Ramirez Elizondo, Laura (graduation committee); Delft University of Technology (degree granting institution)","2018","An increase in carbon emission which mostly caused by the transportation sector and electric power generation has been a hot topic nowadays in most countries in the world. To tackle this problem, the share of renewable energy use has been increased by up to 14% in the Netherlands. Moreover, the number of electric vehicles (EVs) on the road also reaches a total of 120,000 EVs in 2018. However, the high penetration of renewable energy sources (RESs) such as solar & wind power and the EVs charging in the distribution network could result in a severe problem. One of the solutions to avoid this problem is that switching the uncontrolled charging of EVs into a controlled charging or called as smart charging. Further, an integration between the EVs, RESs and the distribution grid could potentially lead to technical and economic benefits. The focus of this thesis is to develop an optimal power management system (PMS) between the EVs, PV system, and the distribution network. The goal of the power management system is to obtain the minimum operational cost while also considering the technical grid constraints, which subsequently could avoid the grid violation. The proposed power management system will be modeled in a mixed integer non-linear programming (MINLP) optimization problem and executed in General Algebraic Modelling System (GAMS) software. To evaluate the performance of the proposed power management system, a comparison between the with-grid and the no-grid constraints case will be performed through several case studies. This study shows that by implementing the proposed power management system of EVs charging from PV system considering the grid constraints, it could decrease the total operational cost remarkably by 18.16% - 214.08% when compared to the uncontrolled charging scheme. Besides, the grid problem caused by the uncontrolled charging process such as exceeding the allowable voltage deviation and the transformer rated power could be prevented. However, in comparison to the smart charging without considering the grid constraints, the operational cost is increased by 1.43% - 113.20%.","Smart charging; Electric Vehicles; Optimization; PV systems","en","master thesis","","","","","","","","","","","","Sustainable Energy Technology","","" "uuid:2cc94bdd-857d-48fe-9140-5b7e8cfa001f","http://resolver.tudelft.nl/uuid:2cc94bdd-857d-48fe-9140-5b7e8cfa001f","Optimal Wind Farm Lifetime Power Production","Cheng, Ken (TU Delft Aerospace Engineering)","Odgaard, Peter Fogh (mentor); Bierbooms, Wim (mentor); Kim, Taeseong (mentor); Jørgensen, John Bagterp (mentor); Delft University of Technology (degree granting institution); Denmark Technical University (degree granting institution)","2018","This project is a collaboration between Goldwind, Technical University of Denmark (DTU) and Delft University of Technology (TUDelft), of which focusing in developing an optimization model that could determinate the optimal operation schedule for wind turbine under the uncertainty of the electricity price and limitation in life-time equivalent fatigue loads, for the purpose of improving and maximizing the revenue or cash flow for wind farm project.

The project comprises of two main parts, including the design and validation of up- and de-rated operation modes, and the model development and optimization of the revenue. The design of the different operation modes provide varies rated power without sacrificing the life-time structural integrity, as such offer extra flexibility in wind turbine operation schedule according to the fluctuation in electricity price. Life-time equivalent loads would be calculated for the different operation modes design and a weighting factor, that indicate the rate of fatigue consumption relatively to the normal operation, would be computed and used in the optimization process. An optimization model is developed based on the turbine structural constraints as well as the financial profile. The optimization model processes the electricity price data and other wind turbine data, for example the fatigue consumption, to reproduce the optimal operation schedule and operation price thresholds that would yield utmost financial benefits.

The optimizer has a proven performance improvement in revenue generation of 1.5% and 5% reduction in the project related interest payment under one of the case study under electricity price uncertainty. The model is effective in scheduling the turbine operation upon the varying electricity price. This optimization model is providing game changing insights and operation strategies that could be used throughout the turbine life-time under the ever changing electricity price of the energy market. And further drive down the cost of energy in the highly competitive market. By improvising continuous input to the optimizer including bending moment sensors inputs, the optimization process could reproduce a more accurate revenue improvement.","Wind Energy; Fatigue Analysis; Optimization; Cost of Energy","en","master thesis","","","","","","","","2023-08-16","","","","European Wind Energy Masters (EWEM)","","" "uuid:3d712eb2-5d6f-4526-8f2c-becc2eeaa13f","http://resolver.tudelft.nl/uuid:3d712eb2-5d6f-4526-8f2c-becc2eeaa13f","Optimal Design of Wind Turbine Blades with Bend-Twist Couplings Effects","Roeleven, Niek (TU Delft Aerospace Engineering)","Holierhoek, Jessica (mentor); Langelaar, Matthijs (mentor); Stolpe, Mathias (mentor); Alderliesten, Rene (mentor); Lund, E. (mentor); Delft University of Technology (degree granting institution)","2018","This thesis concerns the optimal design of wind turbine blades for bend twist coupling effects. Bend-twist coupling effects can prove to be an effective way of reducing fatigue damage and root bending moments for a wind turbine blade. However, how can bend-twist coupling be incorporated into a wind turbine blade considering the many structural requirements? This thesis investigates the optimal design for bend-twist coupling in wind turbine blades. Gradient based

numerical optimization algorithms are applied to obtain composite material layups favorable for bend twist coupling. The thesis work builds a framework that allows for the selection of fiber angles at several sections along the blade, while considering structural constraints. This involves the use of a cross section analysis software and a finite element beam formulation for the evaluation of responses, while an aeroelastic software is used for load mitigation validation.

The structural constraints include tip twists and deflection, eigenfrequencies and material failure criteria of which the analytic sensitivities are calculated, implemented in the framework and validated against central finite difference gradient values. A simple cantilever sandwich beam is considered first as a trial for the framework and four problem formulations are defined to test both the framework and the considered optimization algorithms. A full scale wind turbine blade for a 10MW wind turbine is then subject for the optimization. A converged design for the full scale blade is obtained and subject to aeroelastic simulations in a steady state and turbulent inflow. From this, the load mitigation effects are observed and discussed. With the work done in this thesis project, a step closer to an effective framework for aeroelastic tailoring is achieved.","Optimization; Wind Turbine Blade; Bend-twist coupling","en","master thesis","","","","","","","","","","","","","","" "uuid:efd1c23f-4ab7-41dd-88e4-e9a1683c4ccc","http://resolver.tudelft.nl/uuid:efd1c23f-4ab7-41dd-88e4-e9a1683c4ccc","Computational Design Method Based on Multidisciplinary Design Optimization and Optioneering Techniques for Energy Efficiency and Cost Effectiveness","Rodriguez Garcia, Alvaro (TU Delft Architecture and the Built Environment)","Turrin, Michela (mentor); van der Spoel, Willem (mentor); Delft University of Technology (degree granting institution)","2018","One of the cutting-edge interests gaining relevance among design offices, notably in the sphere of architecture firms, is computational design. With its inception embedded in the 60s and later reformed through the CAD revolution that boomed in the 80s, the use of the computer as a design tool has evolved to such lengths that it became indispensable to contemporary practices. Nowadays, under the bright prospect of a challenging future and considering the sustainability hypothesis - sophisticated computational approaches and parametric design can genuinely be considered a most promising alternative for exceeding outcomes in the fields of performance and efficiency.

Thus, under this spectrum, the following research focuses on investigating the evolution of the aforementioned tools, through understanding the current user experience and interface in prevalent architectural offices. Consequently, through the use of existing computational tools - simulations, optimization and design exploration techniques - it will put forward a new method and use pattern that would also project the potential and the future of these technologies, specifically applied to a sustainable, energy-efficient and cost-effective vantage.","Computational Design; Optimization; Performance Based Simulations; Multidisciplinary Design Optimization; Energy Efficiency; Costs effectiveness; Sports Facilities; Workflow; Optioneering","en","master thesis","","","","","","","","","","","","Building Technology | Sustainable Graduation Studio","","" "uuid:0ad5f3cc-a5e9-45c0-a37e-75e139713409","http://resolver.tudelft.nl/uuid:0ad5f3cc-a5e9-45c0-a37e-75e139713409","Thermal Morphology: A Geometrically Optimized Trombe Wall","Farrugia, Eve (TU Delft Architecture and the Built Environment)","Tenpierik, Martin (mentor); Turrin, Michela (mentor); Delft University of Technology (degree granting institution)","2018","Recently, there has been a growing interest in passive climate design aimed at reducing the large energy demand arising from existing buildings. Sustainable consumption of quantities of energy by buildings has necessitated research into innovative designs for comfortable and energy-efficient buildings. This graduation project branches out from this research field and focuses on experimentation with geometry and its effects on thermal mass in the context of architecture.

It is known that geometry has an impact on thermal performance, however information regarding alternatives for material distribution to improve thermal performance is somewhat limited. The main objective of this research is to identify how geometry could influence and enhance the thermal performance to reduce the overall energy consumption in a specific context. This graduation project focuses on thermal mass in the form of a trombe wall in office building typologies. It also targets the use of translucent Phase Change Materials (PCM) as a thermal energy storage material for lightweight building components in the context of two different climates; a hot and dry climate and a temperate climate.

A combination of simulation and modelling software is used to determine the effect of geometry on the thermal performance of the trombe wall with PCM in two different climates. A stepped methodology is used to morph a flat wall following a series of design strategies and two different geometry scales. By analysing the differences in air and PCM temperatures it is determined whether geometrical morphology is beneficial in terms of a comfortable air temperature in an office.

General trends are identified which highlight the potential of material distribution in thermal performance in the context of PCM and trombe walls. These trends are then transformed into design guidelines and two different designs for a trombe wall with translucent PCM in the two climates.","Morphology; Thermal Performance; PCM; Trombe Wall; Optimization; Energy Efficiency; Thermal comfort; Geometry","en","master thesis","","","","","","","","","","","","Building Technology | Sustainable Graduation Studio","","" "uuid:b67eae7d-4d5a-47d2-a320-cf0e14944852","http://resolver.tudelft.nl/uuid:b67eae7d-4d5a-47d2-a320-cf0e14944852","Automatic Selection of an Optimal Power Plant Configuration: Using Client Preferences and time based Operational Profiles","van Dijk, Jitte (TU Delft Mechanical, Maritime and Materials Engineering)","de Vos, Peter (mentor); Boogaart, R (mentor); Visser, Klaas (graduation committee); Atasoy, Bilge (graduation committee); Delft University of Technology (degree granting institution)","2018","Vessels are becoming more and more optimized towards their mission and an increasing amount of systems are considered during this optimization. Most of these considerations occur at an early design stage, where data is scarce and their impact is large.

This research aims to aid designers in considering this growing forest of possible system using concept exploration. During this exploration both the mission of the vessel and the wishes of the owner of said vessel (or client) are considered.

To do so a methodology is developed, which compares a large set of possible power plant configurations based on fuel consumption, emissions, system mass and volume.

To obtain data for these four characteristics the design of each power plant is required. To obtain this the systems inside a power plant have to be designed individually. During the design of these systems several design choices are encountered.

These choices are solved using the preferences of the client, which are defined as multi criteria weight factors related to the aforementioned characteristics. And as such create individual systems and from that a power plant configuration, which is optimal according to the client.

The entire selection process is demonstrated using three separate cases; a bulk cargo carrier, a harbor tug and a Trailing Hopper Suction Dredger.

This thesis investigates the methods used to estimate the model parameters which influence the resulting vehicle simulation. Experimental tests were carried out to acquire vehicle body inertial measurement data. This data was used to minimize lateral acceleration and yaw-rate error produced by the output of a single track vehicle model using a simplified Magic formula developed by H. Pacejka.

Deterministic gradient-based algorithms, such as multi-objective Sequential Quadratic Programming (SQP), are frequently used as a way to optimize an initial approximation of the model parameter set. It is shown that this initial parameter strongly influences results of the algorithm due to local minima.

As an alternative, genetic algorithms were investigated to minimize the influence of the initial parameter set. An adaptive component, Temporal Difference Q Learning (TDQL), was also added to further reduce the input of the user and to increase the performance of the algorithm.

Four algorithms, of various complexity, were implemented in Matlab and executed. The performance of the resulting parameter sets, as well as the performance of the algorithms themselves, were analysed and compared. It is concluded in this thesis that the adaptive genetic algorithm performs slightly better than a simple gradient-based algorithm with respect to the objectives and the duration of the algorithm. However, a genetic algorithm without TDQL is recommended for its good performance and the simulation flexibility of the results for this simple vehicle and tire model.","Vehicle dynamics; Machine Learning; Parameter Estimation; Optimization; Tire Dynamics; Magic Formula; Algorithm","en","master thesis","","","","","","","","","","","","","","" "uuid:6e274095-9920-4d20-9e11-d5b76363e709","http://resolver.tudelft.nl/uuid:6e274095-9920-4d20-9e11-d5b76363e709","Fuel Cell and Battery Hybrid System Optimization: Towards Increased Range and Endurance","Hoogendoorn, Joey (TU Delft Aerospace Engineering)","Voskuijl, Mark (mentor); de Boer, Alte (mentor); van Benthem, Roel (mentor); Veldhuis, Leo (graduation committee); Roling, Paul (graduation committee); Delft University of Technology (degree granting institution)","2018","Aircraft manufacturers are increasingly exploring emission-free flight or emission reduction for larger passenger aircraft. The low energy density of state-of-the-art battery technology limits the application to small, electric, fixed wing aircraft up to a flight time of approximately one hour. To overcome these limits, a combination of fuel cells and batteries to exploit the benefits of battery power density and hydrogen energy density was studied. Current Lithium-Ion battery cells reach approximately 1.6 kW/kg of maximum power density, much higher than fuel cell systems. On the other hand, the energy storage capacity of suitable hydrogen storage methods is much larger than battery cells, the latter have an energy density of 240 Wh/kg.

Because most demonstrated applications are for fixed wing aircraft, the unmanned GeoCopter GC-201 helicopter was used for performance requirements, weight and volume analysis. The study focuses on the preliminary sizing of the powertrain and the optimization of fuel cell and mission profile variables for this vehicle. Helicopter performance modelling, fuel cell static behavior as well as a battery discharge simulation are combined with lower fidelity models for other components.

The study results in a comparison of battery-only and fuel cell-battery configurations through payload-range diagrams, allowing for a quick evaluation of application areas. These mainly show that batteries excel at high payload, low range applications whereas a fuel cell-battery combination shows clear advantages at low payload, longer range applications. Liquid hydrogen will be shown to be comparable to the current micro gas turbine powered rotorcraft, with 400 and 500 km range capabilities respectively. Range capabilities for 300 bar and 700 bar compressed gas tank storage options show 140 and 180 km, with battery-only reaching a maximum range of 80 km.","Fuel Cell; Batteries; PEMFC; Helicopter; UAV; Lithium-Ion; Preliminary Sizing; Optimization; Endurance; Range; Hybrid; Unmanned; Rotorcraft","en","master thesis","","","","","","","","","","","","Aerospace Engineering","","" "uuid:f9a658fe-9d0b-4a1d-808a-908698c8e8c2","http://resolver.tudelft.nl/uuid:f9a658fe-9d0b-4a1d-808a-908698c8e8c2","Analysis of an over the wing based distributed propulsion system","Khajehzadeh, Arash (TU Delft Aerospace Engineering)","Veldhuis, Leo (mentor); Hulshoff, Steven (mentor); Delft University of Technology (degree granting institution)","2018","This project aims to investigate propeller wing interaction of an over the wing (OTW) based distributed propulsion (DP) system with the addition of a secondary wing. This research explored the opportunities that OTW configuration provides to DP concept, such as improving the lifting performance of system by inducing the flow over the upper surface of wing. Secondary wing is oriented in a biplane configuration above propeller and intends to improve propeller’s performance by decreasing propeller’s inflow velocity. This research aimed to investigate the influence of shape and position modification on the system’s aerodynamic performance and overall propulsive efficiency. The influence of spacing between the wings, position of propeller, secondary wing’s angle of attack and secondary wing’s initial lift coefficient on aerodynamic performance and overall propulsive efficiency of DP system was investigated in this project.

The analysis of this particular configuration was performed with the help of Euler calculations. Eliminating viscous effects from the analysis, reduced the demanded computational cost of this study and could help this research to perform a broader investigation. The influence of isothermal flow condition on Euler calculation was examined to reduce the computational cost of optimization study; This study showed that the drag coefficient of system is sensitive to this assumption and that only by simulating the initial and final points of the optimization study with adiabatic flow condition, the use of isothermal flow condition could be justified. The secondary wing’s shape was optimized to study the influence of its shape variation on the system’s aerodynamic performance. The first optimization study aimed to decrease the drag coefficient of system, and as a result, overall propulsive efficiency of was improved. The second optimization study aimed to improve the lifting performance of system. As a result, the drag coefficient of system significantly increased, however, the overall propulsive efficiency was again improved. The flow decelerated between main wing and secondary wing since the lifting performance of secondary wing improved, which increased the propeller’s thrust according to blade element method (BEM) calculation.

Because of these chain effects, synergizing water, food, and energy policy is no easy task. Unconnected institutional entities further complicate this. Farmers are promoted to grow water intensive rice while at a nearby city faces a drinking water crisis.

Sustainability regulations encourage the replacement of food crops by biofuel crops while elsewhere forests are cut to make place for food production.

The ‘Nexus’, that is an acronym for the interrelated WEF system, and the need to obtain integrated policies was globally advocated. Several analytical Nexus models where developed but left a lot to be desired according to critics. The main critique of these models so far has been that many cannot serve as a

decision support tool because they lack the ability to investigate specific governance actions or the implementation of technical interventions. These models generally have intensive data requirements and are not scalable and flexible enough to perform for many Nexus studies within a single model framework.

In this study an optimization model framework is proposed, titled ‘MAXUS’, specifically designed to address the shortfalls of current models. It was built to customize a model for a specific Nexus study. To test the methodology of MAXUS it was applied to a case study for Ghana and Burkina Faso. Allocation of water and land resources for the final supply of WEF was optimized over space and time, for the objective and constraints given.

It demonstrates how sectors could respond in harmony to changes occurring in one of the sectors. The model shows non-trivial, multi-sectoral, spatial and temporal trade-offs for operational management and infrastructural planning of WEF sectors. For example, changing locations of proposed irrigation capacity because of an increase in electricity demand.

Moreover, the case study demonstrated how it can support in decision making on cross-border cooperation by means of separate optimization for Ghana and Burkina Faso. It showed how sharing resources and open trade would lead to a large reduction in infrastructural requirements. In case of non-cooperation, it

would be beneficial for Burkina Faso to expand reservoir storage capacity and irrigation capacity on a much larger basis than in case of cooperation. Mainly because it would not benefit from hydropower production generated in Ghana in case of noncooperation.

It also showed how thermal power production would have to fill up the gap in electricity supply and how food imports would need to compensate for the loss in food production.

MAXUS is built to serve in a wide range of nexus studies. Hence, it is scalable in time and space, has an adaptable data structure and allows customization of objectives, balances, constraints dimensions and decision variables.

Using Maxus to customize a model for a specific cases study requires broad expertise. It requires engineers to set-up the equations for the model, experts in different sectors that understand the interactions, and local experts that now the

conditions that apply in the case study area. Furthermore, it demands policymakers to think through their ambitions, their preferences, their range of possible interventions and governance actions, and the influences of their decisions on each of the WEF sectors. Exploring strategies for responding to developments in the WEF sectors requires cooperation of all sectors.","Nexus; Optimization; Water management; Integration; Policy; Water; Food; Energy","en","master thesis","","","","","","","","","","","","","","7.9527706, -1.0307118" "uuid:78ae5715-d079-4a7e-983c-d999ba761c16","http://resolver.tudelft.nl/uuid:78ae5715-d079-4a7e-983c-d999ba761c16","Towards the Automation of Preliminary Bridge Designs with Parametric Design Software: Assessment and optimization of multiple steel-concrete bridge typologies","Fransen, Edward (TU Delft Civil Engineering and Geosciences)","Nijsse, Rob (graduation committee); Eigenraam, Peter (graduation committee); Smits, Joris (graduation committee); Freriks, W.G.M. (mentor); Delft University of Technology (degree granting institution)","2018","This thesis concerns research into the parametric modelling and optimization of steel-concrete bridge typologies typically found in the Netherlands, in order to further the automation of preliminary bridge designs. The research question posed is: ""How can a parametric bridge design model be composed to fit into the

overall road design process in order to get a comparative overview of structurally sound bridge designs of different typologies?"". Within the literature review some background information is provided about the design of steel-concrete bridges, parametric design, finite element modelling and evolutionary solvers for optimization. With this information seven different bridges are designed according to boundary conditions and requirements posed in a fictitious case. These bridge designs cover the beam-, truss-, arch- and cable stayed

bridge typologies. The designs are then parametrically modelled and converted to a finite element model in a single parametric design environment, after which they are structurally analysed and optimized for minimum costs. The result is that, for the fictitious case considered, the Warren truss without verticals is the

solution with the lowest costs. This bridge design is able to carry the loads, according to load model 1 from the Euro Codes,with a lower amount of structural steel compared to the girder beam bridges, and the absence of expensive cables in the structure makes it less expensive than the arch and cable stayed bridges. Due to the scope defined at the start of the research, there are some limitations. The costs calculated for the bridges are purely based on the bridge structure itself, foundations and approach structures are not considered and this has to be kept in mind when comparing the bridges. Finally, the research into how to implement this design and optimization tool into the overall design process has not been performed, however, the model is composed in such a way that it will be compatible with minor changes to the start and end of the process.","Parametric design; Steel; Bridges; Concrete; Optimization; Automation","en","master thesis","","","","","","","","2019-02-21","","","","Building Engineering","","" "uuid:2a15115f-6d70-4057-abda-eabf1adc72a7","http://resolver.tudelft.nl/uuid:2a15115f-6d70-4057-abda-eabf1adc72a7","The Improvement of Simulation Correlation for Formula 1: With a focus on kerb riding","Koek, Bart (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Systems and Control)","Hellendoorn, Hans (mentor); Alirezaei, Mohsen (mentor); Shyrokau, Barys (graduation committee); Delft University of Technology (degree granting institution)","2018","The highly competitive nature of Formula one makes every team eager to find areas of improvement on their cars. In the case of Scuderia Toro Rosso, it was found that there is a gap to improve performance while driving on kerb stones. Analysis of competitors showed that they can take wider driving lines with more speed. In order to improve this performance, the need for a high fidelity dynamic car model arose. This model can be used to understand the car dynamics, which can be used to choose a better suspension setup.

The baseline model used for this study was developed in MSC.Adams. After a discussion with field experts, two areas of model improvement were identified. In the baseline model, the tire is modeled using a MF-Tire model, where the vertical dynamics was modeled as a single spring and damper. In order to simulate the tire dynamics on kerb stones, a more advanced model is necessary. For this research, FTire was chosen as the best option. The other area of improvement is modeling the compliance of the suspension system. In the baseline model,

all suspension members are modeled as rigid links, without any compliance. To model this compliance, an ’equivalent stiffness’ model was proposed, where all stiffnesses are combined into flexible joints.

To use the FTire model, a set of parameters needs to be found for the Formula one tires. To find these parameters, measurements were done to capture the dynamics of the tire. A method is developed to filter out any rig disturbance, and make the data useful for parameter estimation. The estimation was done using Matlab, with MSC.Adams and FTire in-the-loop, and made use of a Genetic Algorithm (GA). Comparing the simulated behavior with the measurement showed good correlation for various conditions.

Since every part in the car contains some compliance, modeling and measuring every single part would be an extensive task. In order to reduce the complexity, all compliances are combined into a simplified model. In this simplified model, all compliances are modeled in the joints. A Pattern-Search algorithm in Matlab is used in combination with MSC.Adams to find the joint stiffnesses in such way the model matches measurements of the overall car compliance.

To measure the overall improvement, both models are combined into a full car model. The baseline and proposed model are validated against measured track data. From this compare, it can be concluded that the proposed model shows a significant better correlation on kerb simulations. This is mainly due to the fact that the baseline tire model is not capable of simulating the harsh road input. The proposed model provides a more powerful tool for engineers to better understand the car dynamics, and to find the best suspension setup for

kerb riding.","Formula one; Automotive; Motorsport; Compliance; Tire Dynamics; Optimization","en","master thesis","","","","","","","","2023-02-16","","","","","","" "uuid:ba778a47-14c1-45d0-870a-24b698096e3a","http://resolver.tudelft.nl/uuid:ba778a47-14c1-45d0-870a-24b698096e3a","FSI Analysis and Optimization of 3D beam structures","Mozo Gutierrez, Alvaro (TU Delft Aerospace Engineering)","Turteltaub, Sergio (mentor); Maute, K (graduation committee); Delft University of Technology (degree granting institution)","2018","Aiming to enhance the performance of the industrial design process, structural optimization techniques have been proposed as an alternative to traditional design and optimization techniques.

They own the potential of achieving an optimal distribution of the material through the design domain, thus reducing waste loss and weight, and increasing the ability to carry the loads and the overall efficiency of the design.

During this thesis work it has been developed a 3D Fluid-Structure Interaction model for beam-like structures, such as wind turbine blades. The cross-section geometry of the beam can be optimized using structural optimization techniques, such as size, shape or topology optimization.

The proposed 3D beam is partially based on the formulation of the classical beam element for slender beams (Euler-Bernoulli), including Saint-Venant torsional effects for isotropic materials, and with the addition of the terms related with the coupling between axial and torsion, and bending and torsion contributions, which may arise when using non-linear materials.

The stiffness information of the beam is interpolated from its cross-section geometries and materials, which can vary along the beam length.

The cross-section geometries are defined on a XFEM mesh. The fluid and solid domains are specified using a Level Set Function. This provides a smooth geometry and crisp representation of the solid/fluid interface without the necessity of re-meshing, as in the case of classical FEM. A 2D fluid simulation based on Incompressible Navier Stokes flow at low Reynolds number is carried around each cross-section, in order to obtain the aerodynamic loading over its contour. This aerodynamic loading serves as an input for the beam model, to compute deformation of the beam. This deformation is mapped onto the cross-sections, obtaining the updated displacements and rotations of the geometry. With the updated geometry the fluid field is altered and it needs to be updated as well, forming a non-linear iterative process that loops until a converged structure is obtained.

The 3D FSI model is solved on a monolithic Newton-Raphson solver that treats all the equations involved at once. The Jacobian terms derived for the monolithic solving scheme that has been developed for the forward analysis allow a straightforward computation of the sensitivities using adjoint method. This sensitivity analysis makes possible the optimization of the geometry of the cross-sections based on certain criteria and constraints.","3D Beam; FSI; XFEM; Level Set Method; Sensitivity Analysis; Optimization","en","master thesis","","","","","","","","","","","","Aerospace Structures and Materials Engineering","","" "uuid:b7911d19-9b28-445e-bf19-05db3b9f85dd","http://resolver.tudelft.nl/uuid:b7911d19-9b28-445e-bf19-05db3b9f85dd","Structural Design Exploration of High-rise Design Concepts Using Genetic Algorithms","Schagen, Roland (TU Delft Architecture and the Built Environment)","Turrin, Michela (mentor); Oikonomopoulou, Faidra (mentor); Delft University of Technology (degree granting institution)","2018","The adoption of optimization algorithms has been slower in conceptual design compared to the later design phases. The choices made during the conceptual design phase have a large impact on the performance of the result. This research aims to find out why it is so hard to use optimization in conceptual design. Then a method is proposed to solve this issue during the application of optimization on the conceptual design of a case study. As subject of the case study the CCTV building in Beijing is chosen as it is a good example of a building were the concept development is nebulous, the shape is difficult to rationalize, and a small change in the concept can have large impact on the overall performance of the result. The case study was used to develop a method for optimizing design concepts. This method involves the parameterization of the CCTV building envelope, the calculation of its structural performance using an abstracted finite elements analysis, and the use of NSGA II. The result is a deeper insight into why optimization is difficult in the conceptual phase, a method that is considerate of these difficulties, and an analysis tool for this method.","Genetic Algorithm; Ill-defined problems; Optimization; conceptual design; NSGA II; FEM analysis; CCTV tower; structural analysis","en","master thesis","","","","","","","","","","","","Building Technology","","39.91347, 116.45805" "uuid:311d536e-542d-45b5-97d9-f52b2dd4abf3","http://resolver.tudelft.nl/uuid:311d536e-542d-45b5-97d9-f52b2dd4abf3","Application of bio-based FRP on a road traffic bridge","Zarifis, George (TU Delft Civil Engineering and Geosciences; TU Delft Engineering Structures)","Veljkovic, Milan (mentor); Pavlovic, Marko (mentor); Hendriks, Max (mentor); Claassen, W. (mentor); Delft University of Technology (degree granting institution)","2018","The last decades Fiber Reinforced Polymer (FRP) structures start to find their own place in the field of civil engineering applications and quite lately in bridge engineering. Composites are considered highly versatile materials that offer great tailoring on their design. Synthetic fibers and resins are already quite popular especially in applications where low weight, construction speed and high performance are the objectives. However, environmental concerns over the disposability of non-recycle composites is driving the engineering world towards the use of natural composites. Certain natural fibers appear to be advantageous not only in terms of mechanical properties but also in terms of sustainability compared to synthetic ones. However, environmental performance of bio materials is difficult to assess and predict due to their large natural variability. Durability assessment through literature review and optimization of the superstructure of an FRP bridge, accounting for failure modes mostly deriving from high concentrated vertical loading (wheel loading), are the main objectives of this report. In order to deal with the large number of variables and constraints for the design according to existing structural standards, advanced optimization algorithms are employed. In addition, due to lack of analytical formulas for local buckling resistance prediction, Finite Element (FE) analysis is used since it offers a better insight into buckling failure of composite laminates. Finally, an optimization workflow is developed that accounts for all variables and constraints and minimizes the objective, which in this case is the weight of the superstructure. The obtained results form recommendations for the optimum design of a flax and glass FRP bridge, regarding the thicknesses and orthotropy of the cross section’s laminates with L/300 and L/500 maximum deflection requirement, providing a deck slenderness L/16 and a spacing of the web sw = hSP /3. The assessment and the optimization reveals that flax or BioMid FRP could be promising candidates in replacing synthetic fibers for a bridge application as they can compete in performance and weight the synthetic glass FRP for the case of single span bridge and a span range of 10 - 30m.","Bio-based; FRP; Bridge; Optimization","en","master thesis","","","","","","","","","","","","","","" "uuid:58e639f7-ea6a-4e89-baf8-0bfa64c9a7f4","http://resolver.tudelft.nl/uuid:58e639f7-ea6a-4e89-baf8-0bfa64c9a7f4","The feasibility of the energy-only market in a highly renewable European power system","Hollebrandse, Julian (TU Delft Technology, Policy and Management)","Weijnen, Margot (mentor); de Vries, Laurens (mentor); Auping, Willem (mentor); van der Veen, W. (mentor); Delft University of Technology (degree granting institution)","2018","The Netherlands policy on electricity steers towards a carbon neutral power generation in 2050. Among

the studies that focus on long term power system research, none use the starting point of a 100%

renewable power system in 2050. It is unknown if such a system is technically feasible given the

variability of wind and solar. The generation patterns of intermittent renewables differ continuously,

causing the remaining power sources in the system to mitigate the variable IRES generation.

Additionally, it is also unknown to what extent the energy only market can incentivise investment. By

using the PLEXOS electricity market model, the dispatch of CO2 low generation portfolios and the

market prices and net profits of generators can be determined in various scenarios. These scenarios vary

on demand changes, capacity factors for wind and solar and primary fuel prices. The results show a great

sensitivity of an energy only market under the combination of a demand growth and a meteorological

year of low capacity factors, resulting in blackouts and high wholesale market prices. Storage and

intermittent renewables, however, do not benefit enough from a scenario with a high annual market price.","electricity market; energy only; Optimization; renewable energy sources; investment; merit order; intermittency; dispatch","en","master thesis","","","","","","","","","","","","Complex Systems Engineering and Management","","" "uuid:437ca751-3fd6-42c3-933f-72771f025eee","http://resolver.tudelft.nl/uuid:437ca751-3fd6-42c3-933f-72771f025eee","Dig-limit Optimization: Mixed Integer Linear Programming for grade control in open-pit mining","Buist, Jan Willem (TU Delft Civil Engineering and Geosciences)","Wambeke, Tom (mentor); van Duijvenbode, Jeroen (mentor); Delft University of Technology (degree granting institution)","2018","In open-pit mining on a bench level, the dig-limit optimization problem is deciding whether to classify a Selective Mining Unit(SMU) as waste or whether to classify it as ore. SMU’s with high ore grades are proﬁtable for the mining operation, but due to equipment size a whole frame of SMU’s has to be classiﬁed as either ore or waste. In this thesis the dig-limit optimization problem will be solved using Mixed Integer Linear Programming (MILP). The model proposed in this thesis takes the frame constraint and the average grade constraint into account. The main results of the MILP model are in table 1. The results show that MILP can successfully be used to determine the optimal value of a mining operation, however the determination of the dig-limit for larger grids leads to exponential computation time.

This case study was used to investigate the effect of a varying fragmentation on shovel loading time and crusher- and mill performance. The financial impact of a potential blast pattern change was also investigated. After a statistical analysis of the available data on post-blast fragmentation, it was observed that the desired run of mine (ROM) P80 target of 350 mm is rarely met. It was concluded that the ""Kuz-Ram"" model used to predict the fragment size distribution is incorrectly applied, which resulted in a planned blast design that produces a coarse fragmentation with an excessive presence of boulders. This is referred to as ""bad fragmentation"" and proved to contribute significantly to redundant wear-and-tear of mining equipment, delays at the shovel loading operations and the primary crushing station. A correlation between fragmentation and loading time was found after a statistical analysis on the daily average loading time of three Liebherr 9400 shovels. It was concluded that the shovels are only able to produce at the desired rate of 2.4 minutes per truck load when the fragmentation of the ROM meets the P80 target. The Six Sigma principle Define, Measure, Analyze, Improve, Control (DMAIC) was applied to define an accepted interval range of shovel loading time variation (2.4 m. ± 20 s.). This so called target interval was generally not achieved by the shovels. All three shovels show an increase in average loading time during period where the ROM fragmentation was coarser.

Data generated by a VisioRock™ camera showed, in combination with the throughput of the mills, that an appropriate fragmentation is crucial for an efficient milling process. A detailed analysis of the available data, categorized in ""periods of high interest"", demonstrated that the power consumption of the mills significantly increased when the feed consisted of relatively coarse fragments. It was observed that the post-crushed fragmentation was more coarse when a high fraction of the feed originated directly from the pit. This observation proved that the primary crusher is not able to eliminate all boulder related issues prior to the crushing operations as a result of inadequately planned blasts. Due to inaccurate or unreliable data on mill feed, it was concluded that a full mine to mill survey is required to obtain data needed for an accurate optimization of mill performance.

Newmont Ghana Gold Limited (NGGL) stated that at least 2.3M US$ has been saved on a yearly basis since 2015, as a result of the reduction of explosives used through a blast pattern widening. The cost impact analysis showed that it is uneconomical to save costs on explosives by widening the blast pattern, due to the potential downstream effects when the fragment size distribution is affected. The financial data was inconsistent and it is therefore recommended to conduct a detailed analysis to provide insight in the actual overall (financial) benefits of a blast pattern optimization. It is recommended to investigate both ""double-benching"" and the purchase of a continuous surveying camera system. Another recommendation is to narrow the blast pattern down to 3.5 m. by 4 m. so that fragmentation related issues are avoided which are currently to be expected for the continuing production in the Subika- and Awonsu Pit.

x:H and its effect on the performance of thin film solar cells","Rodriguez Luna, Rogelio (TU Delft Electrical Engineering, Mathematics and Computer Science; TU Delft Electrical Sustainable Energy)","van Swaaij, Rene (mentor); Delft University of Technology (degree granting institution)","2017","Solar cells are showing significant promise to become the solution for the growing energy needs of our world. However for this to happen, new disruptive technologies with high efficiency and low cost are needed in the market. One possibility comes from multijunction thin film solar cells based on a-Si alloys and nc-Si. For this purpose a–SiO

Research to increase J

Our aim was to experiment with bandgap grading in the absorber layer of a–SiO

Graded experimental cells results showed that it was beneficial to have a small graded region width in the p-i and i-n region (10-30 nm). Since with this grading length J

The main purpose of this thesis project is to provide a model of the laser-enhanced solar sail dynamics and to establish the advantages of laser-enhanced solar sailing as compared to ""traditional"" solar sailing. The analysis has been pursued focusing on interplanetary missions and considering ideal sails, i.e. sails able to perfectly reflect the impinging radiation.

Normally, for low-thrust interplanetary missions the propellant consumption and time of flight required for the transfers to take place play a crucial role. However, since solar sails do not exploit any propellant, the traditional and laser-enhanced sailcraft performances have been compared by analyzing their flight-time optimal trajectories, focusing on three different mission scenarios: a Mercury orbit rendezvous, Mars orbit rendezvous and Neptune flyby.

These trajectories have been computed by taking advantage of an evolutionary neurocontrol optimizer, in which newly added functionalities have been implemented with the purpose of optimizing laser-enhanced solar sail trajectories.

The trajectory analysis results have shown that, if laser-enhanced sailcraft are used instead of traditional sailcraft, flight time gains in the order of 8-11% can be achieved for the missions to Mercury and Mars orbits, while a smaller 2.5% gain is achieved for the flyby mission to Neptune.","Laser-enhanced; Solar Sail; Ideal; Trajectory; Optimization; Machine Learning; Evolutionary Neurocontrol","en","master thesis","","","","","","","","2018-07-01","","","","","","" "uuid:ccc91e95-a790-4fbc-bcaf-effedc9dbd4d","http://resolver.tudelft.nl/uuid:ccc91e95-a790-4fbc-bcaf-effedc9dbd4d","Towards the Industrialization of MDAO: Evolving 1st Generation MDAO to an Industry Ready Level of Maturity","de Vries, Daniël (TU Delft Aerospace Engineering)","La Rocca, Gianfranco (mentor); Binder, Simon (mentor); van Gent, Imco (mentor); Delft University of Technology (degree granting institution)","2017","Multidisciplinary Design Analysis and Optimization (MDAO) promises major advances in aircraft design. However, judging from todays aircraft, MDAO is clearly not fully embraced by the industry yet. This is due to technical difficulties (coupling incompatible tools) and non-technical barriers (intellectual property).

Recent research, such as the AGILE project, aims at enabling 3rd generation MDO, where collaboration of distributed teams is key. Maturing MDAO is important to eventually make Overall Aircraft Design possible. However, the industry is still in the early days of 1st generation MDO application.

This thesis proposes a new 1st generation MDO 'pipeline' benefiting from the latest tools developed for 3rd generation MDO. This open-source tool-chain makes it easy to connect analyses and include gradient information. It is shown that gradient inclusion yields dramatically reduced computational costs. Rapid (re)configuration and inclusion of gradient information using this pipeline is demonstrated by considering the Sellar problem and a wing optimization.","MDO; MDAO; Optimization; AGILE; OpenMDAO; Framework; Multidisciplinary; Aircraft; Design; Analysis","en","master thesis","","","","","","","","","","","","","","" "uuid:2987341f-d34f-4477-b31f-0cac08cd9c5c","http://resolver.tudelft.nl/uuid:2987341f-d34f-4477-b31f-0cac08cd9c5c","Optimization of the Locations of Virtual Network Functions","Inan, Alp (TU Delft Electrical Engineering, Mathematics and Computer Science)","Kuipers, Fernando (mentor); Klepper, Matthijs (mentor); Delft University of Technology (degree granting institution)","2017","In traditional networks, the network functions are implemented as physical appliances which are called middleboxes and these middleboxes need to be deployed in predetermined locations throughout the network. Therefore one of the most important disadvantages of using middleboxes is that each network function deployment requires a great deal of human work. During their operation, middleboxes need maintenance which also demands for massive human work. Therefore using middleboxes for each network function puts a constraint on the flexibility of the network. Network Function Virtualization (NFV) is a proposed architectural framework which introduces the virtualization of network functions. In NFV, each network function is implemented as software and deployed on data center servers which offers greater network flexibility with the ability of run-time network service deployment throughout the network. With this technology, the places of network functions can be determined for satisfying different requirements such as Quality of Service (QoS) for end-users. Determining optimal locations for Virtual Network Functions (VNFs) is an open research area.

In this research, the optimal placement of VNFs is studied. The objective of this work is determined to minimize the end-to-end Round Trip Time (RTT) between the end users and the deployed network functions while also minimizing the number of data centers used.

First, the problem is formulated using Integer Linear Programming (ILP) and it is shown that it is NP-hard. Therefore an updated problem definition is formulated to propose a heuristic. The proposed heuristic uses the knapsack problem notion to solve the problem in a smaller amount of time with a trade-off in objective value. Lastly, for the proof of concept, the updated problem definition is also formulated using ILP and the proposed heuristic and the ILP formulation are compared under different scenarios.","NFV; Optimization; Heuristic; VNF; ILP","en","master thesis","","","","","","","","","","","","Electrical Engineering","","" "uuid:6b16e0f9-b038-4d53-bc3c-b07d7fbfe957","http://resolver.tudelft.nl/uuid:6b16e0f9-b038-4d53-bc3c-b07d7fbfe957","Design of an Optimized Acoustic Array for Aero-acoustic Research in an Open-jet Anechoic Wind Tunnel","Luesutthiviboon, Salil (TU Delft Aerospace Engineering)","Snellen, Mirjam (mentor); Sijtsma, Pieter (mentor); Malgoezar, Anwar (mentor); Delft University of Technology (degree granting institution)","2017","This work aims to determine the optimal microphone placement on an acoustic array of TU Delft’s ‘V-tunnel’ which is used for beamforming in aero-acoustic studies. The beamforming performance is driven by two parameters; the Maximum Side lobe Level (MSL) and the Main Lobe Width (MLW). The array design should give a good trade-off between these parameters. The proposed optimization method has two optimization loops. First, the main loop consists of design variables used to collectively describe the distribution of microphones. Then the nested loop generates arrays which satisfy the geometry descriptions from the main loop. Finally, the main loop searches for the optimal design variables. The optimized array is able to achieve the MSL below -15 dB up to the distance approximately four times the MLW around the main lobe. Experimental validation was also carried out to compare the optimized array’s performance with a benchmark array and an array from the beginning of the optimization.","Acoustic array; Optimization; Design","en","master thesis","","","","","","","","","","","","","","51.9900102" "uuid:e095b2be-c497-4de4-a55b-25126e960dbe","http://resolver.tudelft.nl/uuid:e095b2be-c497-4de4-a55b-25126e960dbe","Robot Placement for Mobile Manipulation in Domestic Environments","Chawla, Hemang (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Biomechanical Engineering)","Wisse, Martijn (mentor); Kober, Jens (graduation committee); Gaisser, Floris (graduation committee); Delft University of Technology (degree granting institution)","2017","The development of domestic mobile manipulators for unconstrained environments has driven significant research recently. Robot Care Systems has been pioneering in developing a prototype of a mobile manipulator for elderly care. It has a 6 degrees of freedom robotic arm mounted on their flagship robot LEA, a non-holonomic differential drive platform. In order to utilize the navigation and manipulation capabilities of such mobile manipulators, robot placement algorithm that computes a favorable position and orientation of the mobile base is sought, which enables the end effector to reach a desired target. None of the existing approaches perform robot placement while ensuring a high chance of successful planning to target through a short path, while accounting for sensing and actuation errors typical in real world scenarios. This thesis presents a novel robot placement algorithm DeCOWA (Determining Commutation configuration using Optimization and Workspace Analysis) with these characteristics. Since the approach to robot placement is dependent upon the kind of mobile manipulation, a comparative study of sequential and full body methods is performed with respect to criteria important in domestic settings. Sequential mobile manipulation is found to be most suitable, for which a modular mobile manipulation framework encompassing motion planning and robot placement is presented. With sequential mobile manipulation, the ability to successfully reach a target depends upon the kinematic capabilities of the arm. Accordingly, robot placement with DeCOWA determines a favorable location for the arm, and corresponding platform orientation. To find the position of arm’s base, an offline manipulator workspace analysis is performed generating the Inverse Reachability and Planability maps. During online use, these maps are combined into an Inverse Fusion Map that ranks different

locations based on the ability of the arm placed there to find a successful and short motion plan to target. This map is filtered to generate a set of feasible locations at the arm’s height. Through a ranked iterative search, a suitable collision free arm location is determined followed by minimization of the platform distance from robot’s current pose. This approach is evaluated against an unbiased random placement of robot near the target using a sample set of twenty scenes mimicking domestic settings. It is found that DeCOWA is able to generate commutation configurations in fraction of a second, that lead to a high planning success rate, a short path length, and account for goal tolerance of navigation. Also, its modularity allows to use several planability metrics, making it useful for domestic application.","Mobile Manipulation; Robot; Robot Placement; Vision; Domestic Environments; Commutation Configuration; Robotics; Base Placement; Reachability; Workspace Analysis; Optimization; Planability; Algorithm","en","master thesis","","","","","","","","2019-11-10","","","","Biomechanical Design - BioRobotics","","" "uuid:50aaee05-6a0b-4000-b685-572d175d5dd7","http://resolver.tudelft.nl/uuid:50aaee05-6a0b-4000-b685-572d175d5dd7","Optimizing electrodialysis processes for concentrating ammonium rich streams","Deckers, Rob (TU Delft Civil Engineering and Geosciences; TU Delft Water Management)","Spanjers, Henri (mentor); van Linden, Niels (mentor); van Lier, Jules (graduation committee); Witkamp, Geert-Jan (graduation committee); Lindeboom, Ralph (graduation committee); Dewil, Raf (graduation committee); Delft University of Technology (degree granting institution)","2017","Ammonia in aqueous environments leads to eutrophication and toxicity of the receiving water body (Metcalf & Eddy, 2003). In order to prevent environmental pollution, ammonia needs to be removed from residual water streams, before the water can be discharged to the aqueous environment (Song et al., 2012). Waste water treatment plants (WWTPs) reduce the ammonia-nitrogen concentration by applying biological treatment technologies. However, the oxidation of ammonia by bacteria requires high amounts of oxygen and consequently has a high energy consumption. The nitrification and denitrification of wastewater requires 15.83 kWh per kg-N (Magrí et al., 2013). Moreover, the reject water from the digested sludge contains high amounts of nitrogen, which is fed back to the biological treatment, and can contribute 15-20% of the nitrogen load (Fux et al., 2002). Concentrating ammonium fluxes lead to the production of a concentrated ammonium stream, used as potential energy source in the N2kWh project, and a sweet stream.","Electrodialysis; Concentrating; Optimization; ammonia; Brine treatment; Ammonium; Fuel Cell","en","master thesis","","","","","","","","2018-11-07","","","","","From Pollutant to Power","" "uuid:6f3aec1e-9225-431c-b1a8-be635907eb67","http://resolver.tudelft.nl/uuid:6f3aec1e-9225-431c-b1a8-be635907eb67","Modeling and analysis of high frequency high voltage multiplier circuit for high voltage power supply","Qian, Weijun (TU Delft Electrical Engineering, Mathematics and Computer Science; TU Delft Electrical Sustainable Energy)","Mao, Saijun (mentor); Qin, Zian (graduation committee); Bauer, Pavol (graduation committee); Rueda Torres, Jose (graduation committee); Delft University of Technology (degree granting institution)","2017","High frequency high voltage power supply has been widely applied in many industrial applications such as the medical X-ray machine and eletrostatic precipitators. As a part of the high frequency high voltage power supply, the electrical performances of the voltage multiplier circuit will influence the behaviors of applications like the X-ray machine such as the imaging quality. The electrical performances include the output voltage drop and voltage ripple, rise time and decay time of output voltage and power losses. In order to get high imaging quality of the X-ray machine and reduce damage to patients, the multiplier circuit is required to be designed with low output voltage drop and voltage ripple as well as fast respond time.

This thesis concentrates on the investigation of the electrical performances of the Half-wave series Cockcroft-Walton(HWCW) voltage multiplier circuit. The operations in start-up process and steady state are explained in details and methods to evaluate the electrical performances are introduced. Significant parameters of the multiplier circuit that play a role in determining the electrical performances are investigated. Analysis of impact of the parasitic components on the electrical performances are carried out together with simulations. An analytical power loss model is developed in the thesis by deriviations of currents in the HWCW voltage multiplier circuit. At last, optimization of capacitance distributions are discussed and compared to provide methods when selecting the capacitance values in the circuit. The analyses in the thesis are verified by the simulation results in LTspice.","Voltage multiplier; HWCW; Power loss; Optimization","en","master thesis","","","","","","","","","","","","","","" "uuid:581a19ab-1bac-4fbb-a678-bc8e905804d7","http://resolver.tudelft.nl/uuid:581a19ab-1bac-4fbb-a678-bc8e905804d7","Mass optimization of PocketQube structures and deployers: A method demonstrated on the DelfiPQ PocketQube mission","Spronck, Tano (TU Delft Aerospace Engineering)","Bouwmeester, Jasper (mentor); Zandbergen, Barry (graduation committee); Sundaramoorthy, Prem (graduation committee); Fatemi, Javad (graduation committee); Delft University of Technology (degree granting institution)","2017","the aim of this thesis is to regard all aspects concerning mass optimization with respect to small satellite structures and deployers, specifically aimed at the DelfiPQ PocketQube mission.","PocketQube; mass; Optimization","en","master thesis","","","","","","","","","","","","","","" "uuid:044eec5f-c3f9-4021-a7d8-1f3303d3492f","http://resolver.tudelft.nl/uuid:044eec5f-c3f9-4021-a7d8-1f3303d3492f","Thermoeconomic Optimization of Organic Rankine Cycle (ORC) for Low Grade Heat Recovery at Temperatures below 100℃","Arumugam, Senthil Kumar (TU Delft Electrical Engineering, Mathematics and Computer Science; TU Delft Technology, Policy and Management; TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Process and Energy)","Hemmes, Kas (mentor); Woudstra, Theo (graduation committee); Blok, Kornelis (graduation committee); Purushothaman Vellayani, Aravind (graduation committee); Stougie, Lydia (graduation committee); Delft University of Technology (degree granting institution)","2017","Low-grade heat sources are abundant on earth but are majorly untapped due to lower thermodynamic efficiency at low temperatures and cost considerations. A cost-effective technology is needed to convert this energy resource into useful forms of energy. This work aims at optimizing Organic Rankine Cycle (ORC) based heat engine and a cogeneration system developed to produce electricity and refrigeration from a heat source below 100℃, from both thermodynamic and economic point of view. Exergoeconomics, an algebraic thermoeconomic method, was used to analyze and optimize the systems for cost-effectiveness and exergetic efficiency. Also, the prototype of the cogeneration system was experimentally tested. The results exergoeconomic optimization show that the cost-effectiveness of the cogeneration system can be significantly improved by design parameter changes. The experimental results obtained were comparable with the results obtained from theoretical simulations.","exergoeconomics; thermoeconomics; low-grade heat; organic rankine cycle; Optimization","en","master thesis","","","","","","","","2020-10-25","","","","","","" "uuid:538fd43d-5ea8-41ca-8992-7f40f8abc450","http://resolver.tudelft.nl/uuid:538fd43d-5ea8-41ca-8992-7f40f8abc450","Optimum design of freeform-enabled space optical instruments","Menduiña Fernández, Alvaro (TU Delft Aerospace Engineering)","Kuiper, Hans (mentor); Delft University of Technology (degree granting institution)","2017","Nowadays space missions rely heavily on optical payloads to carry out a wide range of tasks including earth observation, weather monitoring, astrophysics research and communications. Until recently, the design of such systems was done according to design principles such as rotational symmetry as it simplifies the theory, reduces technological risks, manufacturing costs and cuts down assembly, integration and testing efforts.

Nevertheless, the ever-growing need to develop more compact and lightweight payloads with enhanced performance often forces designers to adopt tilted off-axis configurations which break the rotational symmetry of the system. In such circumstances, rotationally symmetric optical surfaces cannot compensate the

tilt-induced optical aberrations and thus no longer provide optimum performance over the complete field of view. The solution to this problem is to abandon the conventional approach and adopt a new design paradigmbased on the use of non-rotationally symmetric surfaces, also known as freeform optics.

Most of the state-of-the-art methods used for the design of conventional optical payloads are not entirely suitable for freeform optics because: first of all, they were developed on the basis of rotational symmetry (which is no longer applicable) and secondly, because they do not cope well with the large amount of additional degrees of freedom that freeform optics usually entails. Therefore, this Master Thesis was devoted to the development of a novel methodology for the design and optimization of payloads based on freeform optics.","Freeform; optical instruments; Space Systems; Optimization","en","master thesis","","","","","","","","","","","","Space Exploration","","" "uuid:cc39b153-a799-4cce-aabb-80bf35af44c2","http://resolver.tudelft.nl/uuid:cc39b153-a799-4cce-aabb-80bf35af44c2","Variational Multiple Shooting: Theory and Applications","Greco, Cristian (TU Delft Aerospace Engineering)","Noomen, Ron (mentor); Vasile, Massimiliano (mentor); Schrama, Ernst (graduation committee); Hartjes, Sander (graduation committee); Delft University of Technology (degree granting institution)","2017","Electric low-thrust propulsion has nowadays found wide application in space dynamics as it entails considerable savings in spacecraft propellant mass, thanks to the very high specific impulse that this kind of engine is able to generate. However, continuous thrust opens new extensive sets of feasible trajectories, and optimization algorithms are needed to mine the admissible search space and find optimal transfers. Practical methods to solve complex optimal control problems as low-thrust trajectory optimization typically involve high computational times, the major bottleneck of these techniques. The objective of this work is the development of a novel multiple-shooting optimization tool, employing a variational approach for quick derivative computation, and the assessment of its performance against a variety of test cases. Indeed, after a first analysis of practical optimization methods, the derivative estimation by finite-difference approximations has been found as the major contributor to the computational burden, and the propagation of the variational dynamics has been selected as an accurate approach to speed-up their computation. The theory of variational dynamics for multiple-shooting application has been analyzed in detail, and further developed for what concerns the second-order equations. After practical considerations on the method implementation (scaling procedures, sparsity patterns, et cetera) and its interface with WORHP, the selected non-linear programming solver, the tool has been applied to a broad range of test cases, spanning from elementary problems to practical applications. For what concerns the latter cases, two complex problems were analyzed and optimized: a CubeSat rendezvous departing from Earth-Moon L2 and arriving at asteroid 2000SG334, resulting in a propellant mass convenient trajectory suitable for asteroid reconnaissance well before a proposed NASA manned mission in 2069; The Kessler Run, i.e. the 9th Global Trajectory Optimization Competition (GTOC9), in which the developed tool, employed as last step of the optimization cascade of Strathclyde++ team, managed to make the solution constraint-feasible, valid and further mass-optimal.","Low-thrust trajectories; Optimization; Multiple shooting; Variational equations","en","master thesis","","","","","","","","","","","","","","" "uuid:bfe097c1-6060-4701-b0d6-64c5e9bbb0f3","http://resolver.tudelft.nl/uuid:bfe097c1-6060-4701-b0d6-64c5e9bbb0f3","Vega Launchers' Trajectory Optimization Using a Pseudospectral Transcription","Di Campli Bayard de Volo, Giuseppe (TU Delft Aerospace Engineering)","Naeije, Marc (mentor); Roux, Christophe (mentor); Volpi, Matteo (graduation committee); Gabrielli, Alessandro (graduation committee); Delft University of Technology (degree granting institution)","2017","Given the current technological limitations, launch missions are extremely costly: rockets are huge, being about 100 times more massive than the payload, and most of the times expendable. The specific cost required to place a spacecraft in LEO is between 10 and 25 k€/kg. Consequently, trajectory optimization plays a major role in the design of a launch mission. Universities, companies, agencies and research centers have their own optimization software and continuously try to improve the existing methods. In this context, the main objective of the presented research is to assess advantages and disadvantages of using a pseudospectral approach for launcher trajectory optimization in an industrial context by applying it to the Vega launcher family, namely Vega, Vega C and mini-Vega E.

The software GPOPS is chosen for the transcription of the continuous optimal control problem and SNOPT for the solution of the associated non-linear programming problem. The launcher ascent problem is formulated considering all the main constraints: angle of attack, pitch rate, aerodynamic loads and heat flux. In addition, the dynamic model includes thrust profiles and drag curves of the aforementioned vehicles. The control to be optimized is the direction of thrust and it is formulated in two different ways, allowing to select the most suited for the specific application: Cartesian x-y-z components or pitch-yaw angles.

After numerous tests with all kinds of target orbits (Sun-synchronous, polar, equatorial, escape, etc.), it can be concluded that the PS method and the software composed by GPOPS and SNOPT are suited for practical ascent trajectory optimization: first, all the typical constraints are included and fulfilled; second, the problem formulation is general enough to be easily applied to all kinds of configurations (number of stages, types of motors, etc.) and number of phases (single/multiple boosts, coast, etc.); third, problem formulation allows for both payload mass maximization (preliminary studies) and propellant reserve maximization with fixed payload (industrial application); finally, the obtained performances do match perfectly with the performance maps of ELV. In conclusion, this research provides the hosting company with a validated method and a complete tool, ready for a daily utilization.","Launcher; Optimization; Trajectory","en","master thesis","","","","","","","","2022-09-01","","","","","","" "uuid:446ce1ef-5c16-4ceb-a31b-eab72884b4d4","http://resolver.tudelft.nl/uuid:446ce1ef-5c16-4ceb-a31b-eab72884b4d4","Fast computation of SEP transfers to Mars using analytic curve-fit functions","Galletti, Elena (TU Delft Aerospace Engineering)","Noomen, Ron (mentor); Visser, Pieter (graduation committee); Cowan, Kevin (graduation committee); Delft University of Technology (degree granting institution)","2017","The increasing interest in solar electric propulsion techniques, that enable significant propellant mass savings for a wide class of transfers, has brought about a revolution in the approach to trajectory design and optimization, as a result of the complexity and diversity of the problem. To date, solutions of different nature exist, but numerical methods that require significant computational effort and user experience are typically used already in the early stages of mission design, due to the limited availability of reliable medium-to-low fidelity design tools for SEP transfers. This research project proposes a novel method that computes transfer performance parameters for Earth-Mars mass-optimal SEP transfers, by means of empirically derived analytic relations. The method is intended for applications such as concurrent engineering and early-phase concept development, which require the fast characterization of a broad design space. Besides accommodating a wide range of currently available systems, the method successfully deals with modelling the effect of non-zero infinity velocity at departure and/or arrival.

The methodology that has been applied consists of a first phase of generation and characterization of the transfers, and of the subsequent selection of the model variables, model functions and architecture. Regarding the generation of the transfers, it is assumed that the transfers are coplanar and that the initial and target orbits are circular. Hundreds of transfers are optimized in a semi-automatic way and characterized in terms of thrust profile and transfer performance parameters. In the investigated design space, different regimes are identified, but approximately 90% of the acceleration range of interest falls into the thrust-coast-thrust profile for any combination of departure and arrival infinity velocity. For a proper description of the underlying trends in the transfer parameters, three key variables have been identified, namely the average acceleration, the total infinity velocity and the infinity velocity at arrival (expressed as a function of the total infinity velocity). By means of curve-fitting, analytic relations are derived that successfully describe those trends, limited to the thrust-coast-thrust class of transfers.

The method that is presented computes near-optimal transfers in terms of ΔV cost, transfer time, transfer angle and departure date. While the first three parameters are the outputs of the mentioned curve-fit model above, the departure date is computed by solving analytically the problem of the phasing with Mars, in a subsequent step. The fit functions that are derived model circle-to-circle planar transfers with an accuracy in the order of 0.1% with respect to the ΔV , 1.5% to the transfer time and 1.2% to the transfer angle, successfully dealing with the dependence on the departure and arrival infinity velocities and generating instant estimates for all relevant transfer parameters. When the model performance is considered in relation to transfers derived in the full ephemeris model, the errors are within 1% for the ΔV , within 15% for the transfer time and within 12% for the transfer angle, which, together with the demonstrated efficiency and simplicity of implementation, make it suitable both for early-stage assessments and for generation of suitable first guesses.","Trajectory Design; Solar Electric Propulsion; Optimization; Mars; Curve Fitting","en","master thesis","","","","","","","","2019-09-18","","","","Astrodynamics & Space Missions","","" "uuid:1197caf1-d9ad-4829-bdb8-8c3867e606e9","http://resolver.tudelft.nl/uuid:1197caf1-d9ad-4829-bdb8-8c3867e606e9","Modelling Approach for Special Properties of Magnetic Materials Applied in Actuators","Zhang, Jie (TU Delft Electrical Engineering, Mathematics and Computer Science)","Polinder, Henk (mentor); Bax, Peter (mentor); Dong, Jianning (graduation committee); Lahaye, Domenico (graduation committee); Delft University of Technology (degree granting institution)","2017","Eddy currents are loops of electrical currents induced within conductors by varying magnetic field in the conductor. Eddy currents flow in the closed loops in the conductor, in planes perpendicular to the magnetic field. The eddy current effect plays an important role in the transformer or an actuator system.

If there is a coil wound around a cylindrical iron core, system, the AC coil can induce eddy currents in the solid core. The eddy current can change the flux in the core, and further influence the impedance of the system. If such a system is applied to an electromagnetic actuator, a proper modeling approach for the eddy current effect can help the researchers to determine the impedance change and predict the output power of the actuator. This thesis deals with the eddy current modeling improvement problem. A concept of the transformer ring topology is proposed to simplify the actuator model. A brass ring and an iron material ring are studied, in the purpose of realizing modeling optimization and test functions respectively. By using analytical calculation and modeling analysis, the eddy current modeling method is improved and optimized. The practical impedance of the model becomes closer to the simulation results. This research can help the researcher to compute the actuator model, and better simulates it.","Eddy current; Modelling; Optimization","en","master thesis","","","","","","","","","","","","Electrical Sustainable Energy","","" "uuid:611d466d-3d26-4b32-99e6-e98a805435e8","http://resolver.tudelft.nl/uuid:611d466d-3d26-4b32-99e6-e98a805435e8","Ore Pass Design And Placement","Koivisto, Mikko (TU Delft Civil Engineering and Geosciences)","Buxton, Mike (mentor); Rinne, M. (mentor); Lottermoser, B.G. (mentor); Toodu, Elen (mentor); Delft University of Technology (degree granting institution)","2017","A current trend in mining is towards lower grade deposits when easy to access mineral deposits are depleted in the world. Therefore, to make the current deposits accessible, a cost of mining need to be economic. Costs can be decreased in equipment and mine planning to maximize the availability and utilization of equipment for example by decreasing travelling and hauling distances in daily production. Ore passes are one of the possibilities to decrease hauling costs when mine is evolving the greater depths.

Ore pass design and placement is conducted using modified Bieniawski’s design strategy for rock structures. Thesis studies in detail all parameters affecting to the ore pass design and placement. With the strategy and data available from mine and literature, a case study for Kittilä Mine had been carried out.

Data collection from literature review and data acquired from the mine site was made and applied in the Bieniawski’s design strategy. Production related factors were weighted more in the design process in order of mining to assess the ore pass design and placement. The location and design of the ore pass were optimized using a state-of-the-art technology and best practices in combination with mathematically optimized location.

Via strategy it was possible to identify the project risks, technical viability and feasibility of the ore pass project. Case study shows that via applying the design strategy it is possible to show that mine can benefit from using ore passes in its operations and that ore passes are financially viable solution if ore passes can be operated the way presented in this study.","Ore pass; Mining; Mine Planning; Optimization; Underground Mining; Hauling","en","master thesis","","","","","","","","","","","","","","" "uuid:c49d9752-0052-4db0-af20-15477951f6fd","http://resolver.tudelft.nl/uuid:c49d9752-0052-4db0-af20-15477951f6fd","Optimization of a wind turbine blade-root connection","Rao, Athul (TU Delft Aerospace Engineering; TU Delft Aerospace Structures & Materials)","Shroff, Sonell (mentor); Bellotto, Valter (graduation committee); Delft University of Technology (degree granting institution)","2017","For several years T-bolts have been a popular choice for joints in the field of wind energy, specifically for connecting the blade roots to the hub of the wind turbine. Their use is mandated by the geometry of the joint and they perform very well under pure axial loading. However recent analyses have shown significant bending stresses in the T-bolts preventing their use to their full capacity. These bending stresses are unavoidable due to the presence of a slew bearing between the blade root and the hub. The bending stresses generated while loading the blade root, causes the blade root-bearing joint to gradually open, causing excessive loading of the T-bolt above a certain load.

It is hypothesized that modifying the blade root design to reduce the effects of local bending can open up the possibility of reducing its mass and cost. To test this hypothesis, the blade root is initially studied and the stress ratio is identified as an appropriate joint performance parameter. The performance of the joint is boosted by increasing the pretension of the bolt. After an initial phase of over designing the joint to reduce the constraint stresses, the joint optimization is carried out using the Sequential Quadratic Programming algorithm. The optimization culminates with the mass reducing by roughly 110Kg and the material cost reducing by approximately 13% per blade root. The number of bolts reduces from 88 to 52. Thus, a simpler design is achieved, that promises simpler and cheaper manufacturability, higher reliability and lesser sites for crack nucleation in the laminates. The current design strategy at Suzlon is to employ a greater number of T-bolts with thinner shanks. Curiosity in the field of cost optimization that initiated from within Suzlon has proved that there exists a different design strategy that holds great promise for delivering structurally equivalent if not better designs with improved cost, mass and reliability.","WInd turbine; Blade root; T-bolt; Optimization; Fatigue","en","master thesis","","","","","","","","2022-09-14","","","","","","52.290023, 6.781693" "uuid:ee6dbfd2-f5d2-4366-86f6-d4dcea609d7b","http://resolver.tudelft.nl/uuid:ee6dbfd2-f5d2-4366-86f6-d4dcea609d7b","Optimization of the capacity of a rose sorting system using discrete event simulation","Vreugdenhil, Wouter (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Marine and Transport Technology)","Pang, Yusong (mentor); Bac, Wouter (mentor); Delft University of Technology (degree granting institution)","2017","In Rose cultivation companies in the Netherlands, there is a demand for a higher sorting capacity on the existing sorting systems. The objective for this research is to advice which part of the sorting system needs to be adjusted to gain a higher sorting capacity. For the current sorting systems, five bottlenecks are defined, the bottlenecks limit the sorting capacity. To be able to forecast the effect of machine adjustments, a discrete event simulation model has been constructed, using Simulink and Matlab. This simulation model is verified, matched and validated using data of on an existing rose sorting system. Results of a single day validation showed that the time to process the roses can be simulated with a 97% accuracy. Subsequently, five different simulations are executed. In each simulation, one of the five bottlenecks is removed or reduced. With the results of these simulations the capacity limitation due to each bottleneck is quantified. However entirely removing a bottleneck is not feasible in reality for all bottlenecks. A last situation is simulated where all feasible bottleneck reductions are combined. This showed that the time to sort all roses is reduced by 35%.","Discrete Event Simulation; Rose; Sorting system; Optimization","en","master thesis","","","","","","","","2020-09-05","","","","Transport Engineering and Logistics","","" "uuid:f3c8e60a-65d2-45e1-a838-001a5c21cceb","http://resolver.tudelft.nl/uuid:f3c8e60a-65d2-45e1-a838-001a5c21cceb","Contesting Conservatism with Complexity: Exploring Linear Relaxations of the Positivstellensatz for Robust Stability Analysis of Nonlinear Systems","Fischer-Gundlach, Moritz (TU Delft Mechanical, Maritime and Materials Engineering)","Wolfslag, Wouter (mentor); Wisse, Martijn (mentor); Delft University of Technology (degree granting institution)","2017","Lyapunov's 2nd method can be formulated as a convex optimization problem by means of Sum-of-Squares (SOS) optimization. This gives a powerful tool for robust stability analysis of nonlinear systems. The use of SOS optimization is limited to small dynamical systems, because of the demanding numerical complexity underlying SOS optimization. For systems where scaling of SOS is a concern, diagonally dominant SOS (DSOS) is a possible alternative. DSOS approximates the SOS problem from within and results in a less complex optimization problem. The shortcoming of DSOS, however, is conservatism within the robust stability analysis, entailed by the approximation.

In this thesis, we consider the problem of conservatism in robust stability analysis due to the application of DSOS. We propose new DSOS-based formulations which aim to reduce conservatism in robust stability analysis. Furthermore, we show how to formulate optimization problems which don't require an initial Lyapunov function candidate, and stabilize the numerical solutions of the DSOS problems. The main tool we leverage in this study is the Positivstellensatz in combination with DSOS.

We demonstrate the proposed formulations on three numerical experiments. We estimate the region of attraction of the van der Pol oscillator, investigate stability of an uncertain nonlinear system and proof stability of a nonlinear system, which is documented to suffer from numerical issues when approached with SOS methods. The results show a reduction in conservatism and improvement in numerical robustness when compared to the DSOS formulation found in literature.","SOS; Stability Analysis; Optimization","en","master thesis","","","","","","","","2018-08-25","","","","Biomechanical Design / Biorobotics","","" "uuid:5b0b6016-b8d2-42d3-a9ba-6f18e9c63bca","http://resolver.tudelft.nl/uuid:5b0b6016-b8d2-42d3-a9ba-6f18e9c63bca","The Systematic Search With Assignment Problem Solving (SSWAPS) Algorithm: a New Solution Method for the Nurse ReRostering Problem","van den Dool, Vera (TU Delft Electrical Engineering, Mathematics and Computer Science; TU Delft Delft Institute of Applied Mathematics)","van Essen, Theresia (mentor); Delft University of Technology (degree granting institution)","2017","Hospitals need to be staffed around the clock to ensure satisfactory care for all patients. To this end, a set of shifts is defined which are assigned to nurses in a work schedule. The nurse rerostering problem (NRRP) occurs when due to unforeseen circumstances some shifts become unassigned: one or more nurses are no longer able to work some of the shifts assigned to them. Changes must then be made to the existing schedule to ensure that the shift occupancy demand is once again satisfied. The number of changes should be minimized to disrupt nurses’ personal plans as little as possible. In this paper, a heuristic solution method (SSWAPS) is proposed for the NRRP. The heuristic systematically searches the solution space and estimates the solution quality using the assignment problem.","Optimization","en","master thesis","","","","","","","","2017-09-30","","","","Applied Mathematics","","" "uuid:4e54cfb3-3024-420a-8205-48c7eb767ce9","http://resolver.tudelft.nl/uuid:4e54cfb3-3024-420a-8205-48c7eb767ce9","Parametric Modeling and Optimization of Advanced Propellers for Next-Generation Aircraft","Klein, Peter (TU Delft Aerospace Engineering; TU Delft Aerodynamics, Wind Energy & Propulsion)","Sinnige, Tomas (mentor); Vitale, Salvatore (mentor); Delft University of Technology (degree granting institution)","2017","As traditional fossil fuels become scarcer and more attention is given to environmental impact of the combustion of fossil fuels, for next-generation aircraft, the focus of development will mainly be on reducing fuel consumption. Open rotor engines have the advantage over conventional turbofans that they are expected to perform 25% to 30% better in terms of fuel consumption. The topic of this thesis focuses on one of the current challenges related to open rotor configurations; the unwanted unsteady effects imposed on the aerodynamic characteristics of a propeller, imposed by an upstream pylon. There is a potential for reducing undesired propeller-pylon installation effects by taking these effects into account in aerodynamic design process of the propeller. A propeller design optimization routine is implemented that includes a parametric modeling tool, a low- and high-fidelity performance analysis method and an existing installation effects performance model.","Propeller; CFD; Installed pusher configuration; Optimization; Parametric design tool; Noise; Pylon wake","en","master thesis","","","","","","","","","","","","Flight Performance and Propulsion","","" "uuid:c23bdb6d-72db-42f6-8241-c44b475521f1","http://resolver.tudelft.nl/uuid:c23bdb6d-72db-42f6-8241-c44b475521f1","Estimating the Vulnerability of Ship Distributed System Topologies","van Leeuwen, Simon (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Marine and Transport Technology)","Duchateau, Etienne (mentor); de Vos, Peter (mentor); Visser, Klaas (graduation committee); Negenborn, Rudy (graduation committee); Delft University of Technology (degree granting institution)","2017","All ships rely on many on board systems to reliably complete their missions (e.g. transporting containers, laying pipes or protecting the seas). However, for many of these ships, the detailed design of these systems is put off until the later stages of the design. For most ships, this will create no problems. However, for those complex vessels for which the system design dictates and drives the size and performance of the vessel, changes in a later design stage can be difficult and costly. For these complex ships (e.g. naval ships, pipe-laying vessels, etc), more focus should be spent on system design earlier in the ship design process.

A important aspect of the system design is determining and designing the system topology (e.g. how components within a distributed system are connected). To achieve this, the ongoing PhD research of de Vos [2017] created the ""Ship Distributed Systems Automatic Topology Generator"" (SDS-ATG) tool. This tool combines the fundamentals of network theory and marine engineering to automatically generate a multitude of ship distributed system topology concepts. A genetic algorithm is then used to optimize these topologies with respect to system performance and cost. The performance objective can be related to the vulnerability (or robustness) of the found system topologies.

This MSc thesis focusses on the investigation and development of a vulnerability assessment method, based on network theory, that can be used to assess the generated ship distributed system topologies. The assessment method will be used to better define the performance of a system design, based on the vulnerability of system topologies in early stage design.

To create the method proposed within this thesis, it is necessary to evaluate the created SDS-ATG tool, as well as vulnerability prediction methods and metrics available from literature (and used in other fields). Next, the newly developed vulnerability assessment method is discussed. This discussion is based on the assumptions made to define the method, the steps taken within the method, and the advantages and disadvantages of the method. Finally, the new vulnerability assessment method is verified using hand calculations, and the results of a practical system design test-case are used to show the improvements that can be made with regards to the vulnerability of the system topology design.

To conclude, the developed vulnerability assessment method is seen to greatly increase the capability of the SDS-ATG tool as an eraly stage design tool.

Small-signal analysis is extensively used in power system stability studies. The calculation of the system eigenvalues provides insights regarding the dynamic behavior and the nature of the interactions within the system. However, generating a small-signal representation of power electronic converters is known to be problematic, due to the switched operation of such converters and their complex control structures. Nevertheless, usage of modular multilevel converters (MMC) in HVDC systems is rapidly increasing. This creates the need for extensive studies regarding its dynamic behavior. Due to the MMC unique submodule-based topology, special actions have to be taken if the stability of the converter is to be analyzed.

In this thesis, a small-signal model of a generic MMC was developed by linearizing all the converter plant and control equations, to analyze the converter stability. Averaging was used to eliminate nonlinearities brought forth by the converter switching actions.

The main contributions of this thesis are the application of classic linear-time invariant theory to a time-varying system by linearizing the full converter model at different points in time, and the application of modal analysis methods to the MMC.

The small-signal model was verified against a large-signal one, both developed in Matlab/Simulink. Additionally, the system eigenvalues obtained analytically and numerically —using Matlab/MuPaD and Simulink Control Design Toolbox, respectively — were benchmarked. After obtaining the system state-space matrix, its transfer functions were used to estimate the input impedance of the MMC in the frequency domain. Using the linearized system matrix and an optimization algorithm, namely MVMO, the locations of the converter eigenvalues were optimized by finding a new set of controller gains. Finally, calculating the converter eigenvalues, understanding the effects of these eigenvalues on the system variables and applying advanced tools to tune the controllers of the MMC, and possibly also its main circuit parameters, may aid system designers in controller design and parametrization studies.","Small-signal stability; Modular multilevel converter; Optimization; Small-signal modelling; Voltage-source converter; Eigenvalue analysis; Modal analysis; Participation factors; MMC","en","master thesis","","","","","","","","","","","","Electrical Engineering","","" "uuid:d034d1e2-fd98-4da2-8ddc-c4f6a71acd99","http://resolver.tudelft.nl/uuid:d034d1e2-fd98-4da2-8ddc-c4f6a71acd99","Surrogate Modelling for Airfoil Shape optimization","van Velden, Karel (TU Delft Aerospace Engineering)","Elham, Ali (mentor); Delft University of Technology (degree granting institution)","2017","Airfoil optimizations require costly high-fidelity solvers. By replacing the expensive solver with a cheap to evaluate surrogate model genetic optimization becomes feasible and a global optimum can be obtained. This thesis investigates applicability of surrogate model based optimization for airfoil optimization and provides recommendations regarding parameterization and options for building surrogate models.

Building a surrogate model is done by firstly evaluating an initial sampling with the high-fidelity solver. A surrogate model is fitted through the training data. An iterative process follows that adds sequential sampling points and refits the surrogate model until a stopping criterion is met. The quality of the surrogate model is determined through error analysis.

CST, NURBS and Bezier-Parsec parameterization are investigated for surrogate model building. To build an effective, consistent and efficient surrogate models CST or NURBS without weights is recommended. Sequential sampling plans should be created with LOLA-Voronoi or generalized probability of feasibility. For the surrogate model Kriging is recommended with a minimum sample size of 10 times the amount of parameters.

Final optimization of the structure showed that significant improvement in the objective responses can be achieved by using variable stiffness laminates over a conventional laminate design (UD). The result also implies that reduction in weight can be achieved if a variable thickness optimization is to be done on the model.","Optimization; Variable-Stiffness; Composites; Inertia Relief","en","master thesis","","","","","","","","","","","","","","" "uuid:6818b21f-038d-4700-afcd-e6dac79e7e82","http://resolver.tudelft.nl/uuid:6818b21f-038d-4700-afcd-e6dac79e7e82","On The Cap Set Problem: upper bounds on maximal cardinalities of caps in dimensions seven to ten","Versluis, Nina (Electrical Engineering, Mathematics and Computer Science; Delft Institute of Applied Mathematics)","Gijswijt, Dion (mentor); van Elderen, Emiel (graduation committee); de Groot, Joost (graduation committee); Delft University of Technology (degree granting institution)","2017","This thesis concerns the cap set problem in affine geometry. The problem is illustrated by the card game SET and its geometrical interpretation in ternary affine space. The maximal cardinality of a cap is known for the dimension one to six. For the four lowest dimensions, a maximal cap is constructed and the optimality of its size proven. From there, two recursive methods are described and applied to obtain upper bounds for the maximal size of caps in dimensions seven to ten. The best found upper bounds are 291, 771, 2070 and 5619, respectively.","Affine caps; Affine geometry; Optimization","en","bachelor thesis","","","","","","","","","","","","","","" "uuid:38e13f1e-8424-4a00-bbad-70b9eadf97ac","http://resolver.tudelft.nl/uuid:38e13f1e-8424-4a00-bbad-70b9eadf97ac","Orbit Modeling of Galilean Moons Flybys","Nardi, Alex (Aerospace Engineering)","Noomen, Ron (mentor); Delft University of Technology (degree granting institution)","2017","This research aims at modeling the trajectory followed by the Galileo spacecraft during a variety of flybys about the Galilean moons. The chosen flybys have good Earth’s elevation angles and either low or high closest-approach altitudes, so that the comparison of the two can give relevant insight into the accuracy of the corresponding trajectories. By propagating the state of the spacecraft during these flybys, optimizing the nominal initial state of the spacecraft (obtained through the SPICE program) and the spherical harmonics of the moons, and estimating new harmonics, the minimum root mean square error between the resulting trajectory and the ephemerides by Jet Propulsion Laboratory (JPL) is found. The analysis of its components along the Local Orbital axes gives insight into the existing relation between them and the Earth's elevation and azimuth angles. In particular, a low-altitude flyby implies in general a higher error, but when two flybys have similar altitudes, then the Earth's elevation plays a relevant role and the flyby with the largest one is more likely to have a larger error too. The root mean square error of the fitted trajectories can vary from 15 cm to 7 m, so always less than the 9 m declared by National Aeronautics and Space Administration (NASA) as the maximum error of the moons ephemerides. Furthermore, the flybys about Ganymede and Callisto show a high error in the along-track and cross-track directions, since the radius of their sphere of influence is quite larger than that of the inner moons' ones, hence there is more time for the perturbations to influence the orbit. A by-product of this research is the estimate of the Galilean moons' gravity field, in particular the new values for their J2 and C2,2 coefficients led to the conclusion that Io is less hydrostatic, while Europa and Callisto are more hydrostatic than previously thought.","Galilean moons; Orbit modeling; Flyby; Hydrostaticity; Gravity field; Spherical harmonics; MATLAB; Integration; Propagation; Optimization; Data fitting","en","master thesis","","","","","","","","","","","","","","" "uuid:62636a68-07ba-4244-8036-2f4f9bc133a1","http://resolver.tudelft.nl/uuid:62636a68-07ba-4244-8036-2f4f9bc133a1","Design Optimization of Variable-Stiffness Composite Panels under Thermomechanical Loads","van Loo, Rick (Aerospace Engineering; Aerospace Structures & Materials)","Fatemi, Javad (mentor); Abdalla, Mostafa (mentor); Peeters, Daniël (mentor); Bergsma, Otto (graduation committee); Turteltaub, Sergio (graduation committee); Delft University of Technology (degree granting institution)","2017","Striving to improve structural efficiency the aerospace industry shows increasing interest in variable-stiffness composite laminates. Advanced fiber placement is a hybrid manufacturing technique that offers the flexibility of both filament winding and automated tape laying. With the development of this novel system curved tows can be placed and a spatially variable-stiffness laminate can be designed with continuous changing stiffness from point to point.

The increased design freedom to tailor a structure by in-plane stiffness variation leads to a challenging design optimization problem. A multi-step framework is developed by the aerospace structures and materials department to optimize variable-stiffness laminates. Variable-stiffness laminate design allows for sophisticated designs. Based on this premise it is investigated how such design could improve the structural performance of an engine thrust frame, a structural application that transfers the thrust loads from the rocket engine to the rest of the launch system. The engine thrust frame is subject to cryogenic thermal loads, something not incorporated in the available optimization framework. The goal of this work is to add thermal loads to the laminate analysis routine and to adjust the optimization routine to incorporate thermal influences.

With the thermomechanical optimization framework in place the engine thrust frame is modeled. Conceptual design optimization of the engine thrust frame under thermomechanical loads is performed to increase buckling resistance. A mismatch in the coefficient of thermal expansion is used by the optimal variable-stiffness design. The stiffened areas contract less than the inter-stiffener bay regions. Consequently a stabilizing tensile stress is induced in the prone to buckling bay regions, whereas compressive stresses are distributed to the stiffened areas. Based on the stabilizing thermal stresses and load distribution significant gains in performance are found.