"uuid","repository link","title","author","contributor","publication year","abstract","subject topic","language","publication type","publisher","isbn","issn","patent","patent status","bibliographic note","access restriction","embargo date","faculty","department","research group","programme","project","coordinates"
"uuid:02b64aba-ce12-4be1-bced-567906be8ab1","http://resolver.tudelft.nl/uuid:02b64aba-ce12-4be1-bced-567906be8ab1","Appropriate context-dependent artificial trust in human-machine teamwork","Centeio Jorge, C. (TU Delft Interactive Intelligence); van Zoelen, E.M. (TU Delft Interactive Intelligence; TNO); Verhagen, R.S. (TU Delft Interactive Intelligence); Mehrotra, S. (TU Delft Interactive Intelligence); Jonker, C.M. (TU Delft Interactive Intelligence; Universiteit Leiden); Tielman, M.L. (TU Delft Interactive Intelligence)","Dasgupta, Prithviraj (editor); Llinas, James (editor); Gillespie, Tony (editor); Fouse, Scott (editor); Lawless, William (editor); Mittu, Ranjeev (editor); Sofge, Donald (editor)","2024","As human-machine teams become a more common scenario, we need to ensure mutual trust between humans and machines. More important than having trust, we need all teammates to trust each other appropriately. This means that they should not overtrust or undertrust each other, avoiding risks and inefficiencies, respectively. We usually think of natural trust, that is, humans trusting machines, but we should also consider artificial trust, that is, artificial agents trusting humans. Appropriate artificial trust allows the agents to interpret human behavior and predict their behavior in a certain context. In this chapter, we explore how we can define this context in terms of task and team characteristics. We present a taxonomy that shows how trust is context-dependent. In fact, we propose that no trust model presented in the literature fits all contexts and argue that our taxonomy facilitates the choice of the trust model that better fits a certain context. The taxonomy helps to understand which internal characteristics of the teammate (krypta) are important to consider and how they will show in behavior cues (manifesta). This taxonomy can also be used to help human-machine teams’ researchers in the problem definition and process of experimental design as it allows a detailed characterization of the task and team configuration. Furthermore, we propose a formalization of the belief of trust as context-dependent trustworthiness, and show how beliefs of trust can be used to reach appropriate trust. Our work provides a starting point to implement mutual appropriate trust in human-machine teams.","Human-machine teams; HART; Artificial trust; Appropriate trust; Taxonomy; Context-dependent trust","en","book chapter","Academic Press","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-08-23","","","Interactive Intelligence","","",""
"uuid:c7b3ba18-62ce-43d2-ae95-ae03f72c349e","http://resolver.tudelft.nl/uuid:c7b3ba18-62ce-43d2-ae95-ae03f72c349e","Assessing the Impact of Metrics on the Choice of Prognostic Methodologies","Bieber, M.T. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (Royal Melbourne Institute of Technology University); Santos, Bruno F. (TU Delft Air Transport & Operations)","","2024","Over the past years, advanced prognostic models and approaches have been developed. Most existing approaches are tailored to one specific system and cannot adaptively be used on different systems. This can lead to years of research and expertise being put into implementing prognostic models without the capacity to predict system failures, either because of a lack of data or data quality or because failure behavior cannot be captured by data-driven models. In addition, prognostic models are often evaluated using metrics only related to the correctness of predictions, preventing meaningful evaluation of operational performance. This paper makes use of a framework that can automatically choose prognostic settings based on specific system data. It simultaneously optimizes the choice of methodologies using metrics that capture multiple aspects of prediction quality. We apply this framework to both a simulated data set and a real aircraft data set to characterize the impact of metrics on the choice of prognostic methodologies. The results show that the choice of optimization metric greatly impacts the output of the generic prognostic framework and the overall performance. In addition, a definition for data suitability is provided and assessed on the aircraft system data sets.","","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-07-09","","","Air Transport & Operations","","",""
"uuid:b8aaf6d0-516d-4480-aafc-84e171ed89c7","http://resolver.tudelft.nl/uuid:b8aaf6d0-516d-4480-aafc-84e171ed89c7","Meaningful human control and variable autonomy in human-robot teams for firefighting","Verhagen, R.S. (TU Delft Interactive Intelligence); Neerincx, M.A. (TU Delft Interactive Intelligence; TNO); Tielman, M.L. (TU Delft Interactive Intelligence)","","2024","Introduction: Humans and robots are increasingly collaborating on complex tasks such as firefighting. As robots are becoming more autonomous, collaboration in human-robot teams should be combined with meaningful human control. Variable autonomy approaches can ensure meaningful human control over robots by satisfying accountability, responsibility, and transparency. To verify whether variable autonomy approaches truly ensure meaningful human control, the concept should be operationalized to allow its measurement. So far, designers of variable autonomy approaches lack metrics to systematically address meaningful human control.
Methods: Therefore, this qualitative focus group (n = 5 experts) explored quantitative operationalizations of meaningful human control during dynamic task allocation using variable autonomy in human-robot teams for firefighting. This variable autonomy approach requires dynamic allocation of moral decisions to humans and non-moral decisions to robots, using robot identification of moral sensitivity. We analyzed the data of the focus group using reflexive thematic analysis.
Results: Results highlight the usefulness of quantifying the traceability requirement of meaningful human control, and how situation awareness and performance can be used to objectively measure aspects of the traceability requirement. Moreover, results emphasize that team and robot outcomes can be used to verify meaningful human control but that identifying reasons underlying these outcomes determines the level of meaningful human control.
Discussion: Based on our results, we propose an evaluation method that can verify if dynamic task allocation using variable autonomy in human-robot teams for firefighting ensures meaningful human control over the robot. This method involves subjectively and objectively quantifying traceability using human responses during and after simulations of the collaboration. In addition, the method involves semi-structured interviews after the simulation to identify reasons underlying outcomes and suggestions to improve the variable autonomy approach.","","en","journal article","","","","","","","","","","","Interactive Intelligence","","",""
"uuid:d43f7180-be04-4e5b-a090-993f52433513","http://resolver.tudelft.nl/uuid:d43f7180-be04-4e5b-a090-993f52433513","Cellular balancing under dynamic conditions: A systems biology-based discovery using experimental and modelling approaches","Verhagen, K.J.A. (TU Delft BT/Industriele Microbiologie)","Daran-Lapujade, P.A.S. (promotor); Wahl, S.A. (promotor); Delft University of Technology (degree granting institution)","2023","Saccharomyces cerevisiae, also known as baker’s yeast, is a robust microorganism frequently used in industrial biotechnology. The scale of its applications ranges from several millilitres for research and process development in the lab to hundreds of cubic meters for cultivation in industrial production processes. In large-scale reactors mixing limitations inherently lead to physiochemical gradients in substrate and oxygen concentrations, pH or temperature. Such inhomogeneous environment in production processes can cause a reduced yield or titer compared to the small-scale development processes. Such scale performance differences can lead to significant worse process economics and increase costs and development time.
The scope of this thesis is to study and understand the regulation of Saccharomyces cerevisiae metabolism under dynamic substrate conditions, using both experimental and modelling approaches.","","en","doctoral thesis","","","","","","","","","","","BT/Industriele Microbiologie","","",""
"uuid:0eee41db-eee0-4a49-b9aa-ab96ee09a937","http://resolver.tudelft.nl/uuid:0eee41db-eee0-4a49-b9aa-ab96ee09a937","Introducing CNN-LSTM network adaptations to improve remaining useful life prediction of complex systems","Borst, N.G. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations; Royal Melbourne Institute of Technology University)","","2023","Prognostics and Health Management (PHM) models aim to estimate remaining useful life (RUL) of complex systems, enabling lower maintenance costs and increased availability. A substantial body of work considers the development and testing of new models using the NASA C-MAPSS dataset as a benchmark. In recent work, the use of ensemble methods has been prevalent. This paper proposes two adaptations to one of the best-performing ensemble methods, namely the Convolutional Neural Network - Long Short-Term Memory (CNN-LSTM) network developed by Li et al. (IEEE Access, 2019, 7, pp 75464-75475)). The first adaptation (adaptable time window, or ATW) increases accuracy of RUL estimates, with performance surpassing that of the state of the art, whereas the second (sub-network learning) does not improve performance. The results give greater insight into further development of innovative methods for prognostics, with future work focusing on translating the ATW approach to real-life industrial datasets and leveraging findings towards practical uptake for industrial applications.","Neural networks; Predictive maintenance; Prognostics; Remaining useful life","en","journal article","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:f64abc28-7779-47ad-acf5-1b8973eb971c","http://resolver.tudelft.nl/uuid:f64abc28-7779-47ad-acf5-1b8973eb971c","Personalized Agent Explanations for Human-Agent Teamwork: Adapting Explanations to User Trust, Workload, and Performance","Verhagen, R.S. (TU Delft Interactive Intelligence); Neerincx, M.A. (TU Delft Interactive Intelligence); Parlar, C. (Student TU Delft); Vogel, M. (Student TU Delft); Tielman, M.L. (TU Delft Interactive Intelligence)","","2023","For human-agent teams to be successful, agent explanations are crucial. These explanations should ideally be personalized by adapting them to intended human users. So far, little work has been conducted on personalized agent explanations during human-agent teamwork. Therefore, an online experiment (n = 60) was conducted to compare personalized agent explanations against a baseline of non-personalized explanations. We implemented four agents who adapted their explanations during a search and rescue task randomly, or based on human workload, performance, or trust. Results show that personalized explanations can increase explanation satisfaction and trust in the agent, but also decrease performance. Therefore, we conclude that personalized agent explanations can be beneficial to human-agent teamwork, but that user modelling and personalization techniques should be carefully considered.","","en","conference paper","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-01-01","","","Interactive Intelligence","","",""
"uuid:9a3e1d95-a762-4f99-8647-cb2eed15b4aa","http://resolver.tudelft.nl/uuid:9a3e1d95-a762-4f99-8647-cb2eed15b4aa","Using Kinetic Modelling to Infer Adaptations in Saccharomyces cerevisiae Carbohydrate Storage Metabolism to Dynamic Substrate Conditions","Lao-Martil, David (Eindhoven University of Technology); Verhagen, K.J.A. (TU Delft BT/Industriele Microbiologie); Valdeira Caetano, Ana H. (Student TU Delft); Pardijs, Ilse H. (Student TU Delft); van Riel, Natal A.W. (Eindhoven University of Technology; Universiteit van Amsterdam); Wahl, S.A. (Friedrich-Alexander-Universität Erlangen-Nürnberg)","","2023","Microbial metabolism is strongly dependent on the environmental conditions. While these can be well controlled under laboratory conditions, large-scale bioreactors are characterized by inhomogeneities and consequently dynamic conditions for the organisms. How Saccharomyces cerevisiae response to frequent perturbations in industrial bioreactors is still not understood mechanistically. To study the adjustments to prolonged dynamic conditions, we used published repeated substrate perturbation regime experimental data, extended it with proteomic measurements and used both for modelling approaches. Multiple types of data were combined; including quantitative metabolome, 13C enrichment and flux quantification data. Kinetic metabolic modelling was applied to study the relevant intracellular metabolic response dynamics. An existing model of yeast central carbon metabolism was extended, and different subsets of enzymatic kinetic constants were estimated. A novel parameter estimation pipeline based on combinatorial enzyme selection supplemented by regularization was developed to identify and predict the minimum enzyme and parameter adjustments from steady-state to dynamic substrate conditions. This approach predicted proteomic changes in hexose transport and phosphorylation reactions, which were additionally confirmed by proteome measurements. Nevertheless, the modelling also hints at a yet unknown kinetic or regulation phenomenon. Some intracellular fluxes could not be reproduced by mechanistic rate laws, including hexose transport and intracellular trehalase activity during substrate perturbation cycles.","adaptation; carbon storage metabolism; glucose transport; kinetic modeling; parameter estimation; repeated substrate perturbation regime; Saccharomyces cerevisiae","en","journal article","","","","","","","","","","","BT/Industriele Microbiologie","","",""
"uuid:f132ddf3-1e81-4e81-bfba-cfbee1b48a60","http://resolver.tudelft.nl/uuid:f132ddf3-1e81-4e81-bfba-cfbee1b48a60","Towards neodymium recycling: Analysis of the availability and recyclability of European waste flows","van Nielen, Sander S. (Universiteit Leiden); Sprecher, B. (TU Delft Industrial Design Engineering; TU Delft Energie and Industrie); Verhagen, Teun J. (Universiteit Leiden); Kleijn, René (Universiteit Leiden)","","2023","The world is facing a growing neodymium demand, creating the need for developing a recycling system to handle future waste flows. Recycling technologies are emerging, but the recycling system around them can only be established with knowledge about available end-of-life (EoL) products. Therefore, this study quantified neodymium waste in European countries using material flow analysis, and assessed the recyclability of major EoL products. For 2019, we find a waste flow of 7.7 kt Nd, consisting mostly of NdFeB magnets. HDDs represent a large current waste flow, while the demand for magnets in industrial applications is increasing. In the future, electric vehicle motors and wind turbines likely provide a source of neodymium with good recyclability. Consequently, there will be different product groups that determine the future waste volumes. To manage the changing waste flows, a neodymium recycling system should be developed with the product properties of future waste flows in mind. Meanwhile, the recyclability of products can be improved by addressing bottlenecks in the recycling chain.","NdFeB magnets; Neodymium; Recyclability; Recycling; Substance flow analysis","en","journal article","","","","","","","","","Industrial Design Engineering","","Energie and Industrie","","",""
"uuid:2f3df2e3-b932-4a54-8b84-8a7f1a0e8898","http://resolver.tudelft.nl/uuid:2f3df2e3-b932-4a54-8b84-8a7f1a0e8898","Generic Diagnostic Framework for Anomaly Detection—Application in Satellite and Spacecraft Systems","Bieber, M.T. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Cosson, Fabrice (European Space Agency (ESA)); Santos, Bruno F. (TU Delft Air Transport & Operations)","","2023","Spacecraft systems collect health-related data continuously, which can give an indication of the systems’ health status. While they rarely occur, the repercussions of such system anomalies, faults, or failures can be severe, safety-critical and costly. Therefore, the data are used to anticipate any kind of anomalous behaviour. Typically this is performed by the use of simple thresholds or statistical techniques. Over the past few years, however, data-driven anomaly detection methods have been further developed and improved. They can help to automate the process of anomaly detection. However, it usually is time intensive and requires expertise to identify and implement suitable anomaly detection methods for specific systems, which is often not feasible for application at scale, for instance, when considering a satellite consisting of numerous systems and many more subsystems. To address this limitation, a generic diagnostic framework is proposed that identifies optimal anomaly detection techniques and data pre-processing and thresholding methods. The framework is applied to two publicly available spacecraft datasets and a real-life satellite dataset provided by the European Space Agency. The results show that the framework is robust and adaptive to different system data, providing a quick way to assess anomaly detection for the underlying system. It was found that including thresholding techniques significantly influences the quality of resulting anomaly detection models. With this, the framework can provide both a way forward in developing data-driven anomaly detection methods for spacecraft systems and guidance relative to the direction of anomaly detection method selection and implementation for specific use cases.","anomaly detection; spacecraft systems; metrics; threshold methodologies; time-series data","en","journal article","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:2460fe1c-1d18-4729-a780-0c4c9c7f519f","http://resolver.tudelft.nl/uuid:2460fe1c-1d18-4729-a780-0c4c9c7f519f","Condition-Based Maintenance in Aviation: Challenges and Opportunities","Verhagen, W.J.C. (Royal Melbourne Institute of Technology University); Santos, Bruno F. (TU Delft Air Transport & Operations); Freeman, Floris (KLM Royal Dutch Airlines); van Kessel, Paul (KLM Royal Dutch Airlines); Zarouchas, D. (TU Delft Structural Integrity & Composites); Loutas, Theodoros (University of Patras); Yeun, R.C.K. (Royal Melbourne Institute of Technology University); Heiets, I. (Royal Melbourne Institute of Technology University)","","2023","Condition-Based Maintenance (CBM) is a policy that uses information about the health condition of systems and structures to identify optimal maintenance interventions over time, increasing the efficiency of maintenance operations. Despite CBM being a well-established concept in academic research, the practical uptake in aviation needs to catch up to expectations. This research aims to identify challenges, limitations, solution directions, and policy implications related to adopting CBM in aviation. We use a generalizable and holistic assessment framework to achieve this aim, following a process-oriented view of CBM development as an aircraft lifecycle management policy. Based on various inputs from industry and academia, we identified several major sets of challenges and suggested three primary solution categories. These address data quantity and quality, CBM implementation, and the integration of CBM with future technologies, highlighting future research and practice directions.","condition-based maintenance; integrated vehicle health management; structural health monitoring; prognostics and health management; maintenance planning","en","journal article","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:00c64bf9-b9b7-43b5-a82f-32ded4ad5dc3","http://resolver.tudelft.nl/uuid:00c64bf9-b9b7-43b5-a82f-32ded4ad5dc3","Local characterization of collagen architecture and mechanical failure properties of fibrous plaque tissue of atherosclerotic human carotid arteries","Torun, Su Guvenir (Erasmus MC); Munoz, Pablo de Miguel (Student TU Delft; Erasmus MC); Crielaard, Hanneke (Erasmus MC); Verhagen, Hence J.M. (Erasmus MC); Kremers, Gert Jan (Erasmus MC); van der Steen, A.F.W. (TU Delft ImPhys/Medical Imaging; TU Delft ImPhys/Verweij group; Erasmus MC); Akyildiz, A.C. (TU Delft Medical Instruments & Bio-Inspired Technology; Erasmus MC)","","2023","Atherosclerotic plaque rupture in carotid arteries is a major cause of cerebrovascular events. Plaque rupture is the mechanical failure of the heterogeneous fibrous plaque tissue. Local characterization of the tissue's failure properties and the collagen architecture are of great importance to have insights in plaque rupture for clinical event prevention. Previous studies were limited to average rupture properties and global structural characterization, and did not provide the necessary local information. In this study, we assessed the local collagen architecture and failure properties of fibrous plaque tissue, by analyzing 30 tissue strips from 18 carotid plaques. Our study framework entailed second harmonic generation imaging for local collagen orientation and dispersion, and uniaxial tensile testing and digital image correlation for local tissue mechanics. The results showed that 87% of the imaged locations had collagen orientation close to the circumferential direction (0°) of the artery, and substantial dispersion locally. All regions combined, median [Q1:Q3] of the predominant angle measurements was -2° [-16°:16°]. The stretch ratio measurements clearly demonstrated a nonuniform stretch ratio distribution in the tissue under uniaxial loading. The rupture initiation regions had significantly higher stretch ratios (1.26 [1.15-1.40]) than the tissue average stretch ratio (1.11 [1.10-1.16]). No significant difference in collagen direction and dispersion was identified between the rupture regions and the rest of the tissue. The presented study forms an initial step towards gaining better insights into the characterization of local structural and mechanical fingerprints of fibrous plaque tissue in order to aid improved assessment of plaque rupture risk. Statement of significance: Plaque rupture risk assessment, critical to prevent cardiovascular events, requires knowledge on local failure properties and structure of collagenous plaque tissue. Our current knowledge is unfortunately limited to tissue's overall ultimate failure properties with scarce information on collagen architecture. In this study, local failure properties and collagen architecture of fibrous plaque tissue were obtained. We found predominant circumferential alignment of collagen fibers with substantial local dispersion. The tissue showed nonuniform stretch distribution under uniaxial tensile loading, with high stretches at rupture spots. This study highlights the significance of local mechanical and structural assessment for better insights into plaque rupture and the potential use of local stretches as risk marker for plaque rupture for patient-specific clinical applications.","Atherosclerosis; Digital image correlation; Mechanical testing; Plaque rupture; Second harmonic generation","en","journal article","","","","","","","","","","","ImPhys/Medical Imaging","","",""
"uuid:7b467a6e-3fea-4ac8-9bbd-a99dbc80b17b","http://resolver.tudelft.nl/uuid:7b467a6e-3fea-4ac8-9bbd-a99dbc80b17b","Special issue on ‘new transdisciplinary practices for intelligent manufacturing for industry 4.0’","Peruzzini, Margherita (Università Degli Studi di Modena e Reggio Emilia); Wognum, Nel (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations; Royal Melbourne Institute of Technology University)","","2022","","","en","contribution to periodical","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Air Transport & Operations","","",""
"uuid:a19131d2-0da2-4eb1-811e-0baa6cdb940c","http://resolver.tudelft.nl/uuid:a19131d2-0da2-4eb1-811e-0baa6cdb940c","Perspectieven op circulaire gebiedsontwikkeling: Lessen uit de Binckhorst en andere gebiedsontwikkelingen","van Bueren, Ellen (TU Delft Management in the Built Environment); Buizer, Marleen (Wageningen University & Research); Van den Berghe, K.B.J. (TU Delft Urban Development Management); Heijkers, Bram (Erasmus Universiteit Rotterdam); Meijs, Lucas (Erasmus Universiteit Rotterdam); Verhagen, Teun (Universiteit Leiden); Dittrich, Koen (Erasmus Universiteit Rotterdam); Sprecher, B. (TU Delft Design for Sustainability)","","2022","","Circular Area Development; Circulaire gebiedsontwikkeling; Circular Economy; The Hague; Circular Built Environment","nl","report","Accelerating the Circular Economy Zuid-Holland (ACCEZ)","","","","","","","","","Management in the Built Environment","Urban Development Management","","",""
"uuid:9253925f-325b-4ad4-badb-e6f976ec0c7d","http://resolver.tudelft.nl/uuid:9253925f-325b-4ad4-badb-e6f976ec0c7d","Decision Support Framework for Military Aircraft Fleet Retirement Decisions","Newcamp, Jeffrey M. (USAF Academy); Verhagen, W.J.C. (Royal Melbourne Institute of Technology University); Curran, R. (TU Delft Air Transport & Operations)","","2022","Aircraft fleet managers lack tools to aid decision-making for fleets nearing retirement, which leads to rushed and ill-informed decisions. Accordingly, aging aircraft fleets are underutilized and fleets can be retired before their useful lifetime has been expended. A decision support framework is proposed to solve the aging military aircraft retirement problem. It integrates four steps for fleet managers to simplify the decision-making process: (i) Understanding the structural toll caused by utilization, (ii) Recognizing the indicators that predispose a fleet for retirement, (iii) Determining an optimal fleet size and choosing which aircraft to retire and (iv) Optimizing end-of-life usage prior to retirement. An example using a sample military fleet is used to illustrate the effectiveness of the decision support framework, integrating both computational results and manager judgement. Fleet managers were used to validate the concepts in the framework and their opinions are presented herein. It is shown that fleet managers can utilize a decision support framework to positively impact their decision-making for full-spectrum aging aircraft retirement decisions.","","en","conference paper","American Institute of Aeronautics and Astronautics Inc. (AIAA)","","","","","","","","","","Air Transport & Operations","","",""
"uuid:04872763-171b-435b-9624-55c89f53c3ca","http://resolver.tudelft.nl/uuid:04872763-171b-435b-9624-55c89f53c3ca","The Impact of Prognostic Uncertainty on Condition-Based Maintenance Scheduling: an Integrated Approach","Tseremoglou, I. (TU Delft Air Transport & Operations); Bieber, M.T. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations; Royal Melbourne Institute of Technology University); Santos, Bruno F. (TU Delft Air Transport & Operations); Freeman, F.C. (KLM Royal Dutch Airlines); van Kessel, P.J. (KLM Royal Dutch Airlines)","","2022","One of the challenges of Condition-Based Maintenance (CBM) is to combine health monitoring and predictions with efficient scheduling tools. However, the majority of literature is focusing on the assessment of prognostics algorithms performance. In fact, the added value of these algorithms can only be assessed when considering their impact on maintenance decision process. Furthermore, in practice, when considering the scenario of an aircraft fleet with multiple monitored components, it is hard for a human decision-maker to translate and identify the effect of probabilistic results from all prognostics models from all systems on the maintenance schedule. Therefore, to support the implementation of CBM, the prognostics algorithms have to be integrated within a scheduling framework. Our paper proposes this integration in order to evaluate the impact of different level of prognostics accuracy and uncertainty on the aircraft fleet maintenance scheduling level. First, a Support Vector Regression (SVR) model is used to predict the Remaining Useful Life (RUL) distributions of the monitored components. Second, the maintenance scheduling problem is solved within a Reinforcement Learning (RL) approach incorporating a state-of-the-art Partially Observable Monte Carlo algorithm. Implementing a rolling horizon approach, our proposed framework is applied to a fleet of 10 aircraft, each equipped with multiple monitored systems. A case study with multiple different prediction accuracy and uncertainty scenarios is performed to assess the impact of prognostics uncertainty on optimal maintenance scheduling. The performed analysis aims to guide the development and assessment of prognostic models in terms of accuracy and uncertainty in the context of CBM.","","en","conference paper","American Institute of Aeronautics and Astronautics Inc. (AIAA)","","","","","","","","","","Air Transport & Operations","","",""
"uuid:4b9c9072-d479-4327-bfe2-12457545f8e2","http://resolver.tudelft.nl/uuid:4b9c9072-d479-4327-bfe2-12457545f8e2","The Impact of Metrics on the Choice of Prognostic Methodologies","Bieber, M.T. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations; Royal Melbourne Institute of Technology University); Santos, Bruno F. (TU Delft Air Transport & Operations)","","2022","Metrics play an important part in the development and application of prognostic methodologies as they provide the capability to characterize and assess the quality of remaining useful life predictions. Although there is a wide range of both, prognostic metrics and prognostic methodologies available, the choice of those often is a demanding and time consuming task. Additionally, they are often treated as two separate problems to solve, while the choice of metrics has an impact on the choice of prognostic methodology and vice versa. In this paper, we therefore present a framework with the capability to automatically choose prognostic settings given specific system data to account for five different prognostic metrics. We then apply this framework to an aircraft data set to characterize the impact of metrics on the choice of prognostic methodologies. The results show that the choice of optimization metric has a big impact on the output of the generic prognostic framework and on the overall prognostic performance.","","en","conference paper","American Institute of Aeronautics and Astronautics Inc. (AIAA)","","","","","","","","","","Air Transport & Operations","","",""
"uuid:07b14c2a-4912-4e3d-b2b9-bcaabe42eebb","http://resolver.tudelft.nl/uuid:07b14c2a-4912-4e3d-b2b9-bcaabe42eebb","The influence of interdependence and a transparent or explainable communication style on human-robot teamwork","Verhagen, R.S. (TU Delft Interactive Intelligence); Neerincx, M.A. (TU Delft Interactive Intelligence; TNO); Tielman, M.L. (TU Delft Interactive Intelligence)","","2022","Humans and robots are increasingly working together in human-robot teams. Teamwork requires communication, especially when interdependence between team members is high. In previous work, we identified a conceptual difference between sharing what you are doing (i.e., being transparent) and why you are doing it (i.e., being explainable). Although the second might sound better, it is important to avoid information overload. Therefore, an online experiment (n = 72) was conducted to study the effect of communication style of a robot (silent, transparent, explainable, or adaptive based on time pressure and relevancy) on human-robot teamwork. We examined the effects of these communication styles on trust in the robot, workload during the task, situation awareness, reliance on the robot, human contribution during the task, human communication frequency, and team performance. Moreover, we included two levels of interdependence between human and robot (high vs. low), since mutual dependency might influence which communication style is best. Participants collaborated with a virtual robot during two simulated search and rescue tasks varying in their level of interdependence. Results confirm that in general robot communication results in more trust in and understanding of the robot, while showing no evidence of a higher workload when the robot communicates or adds explanations to being transparent. Providing explanations, however, did result in more reliance on RescueBot. Furthermore, compared to being silent, only being explainable results a higher situation awareness when interdependence is high. Results further show that being highly interdependent decreases trust, reliance, and team performance while increasing workload and situation awareness. High interdependence also increases human communication if the robot is not silent, human rescue contribution if the robot does not provide explanations, and the strength of the positive association between situation awareness and team performance. From these results, we can conclude that robot communication is crucial for human-robot teamwork, and that important differences exist between being transparent, explainable, or adaptive. Our findings also highlight the fundamental importance of interdependence in studies on explainability in robots.","human-robot teamwork; explainable AI; transparency; explainability; interdependence; user study; human-agent teaming; communication","en","journal article","","","","","","","","","","","Interactive Intelligence","","",""
"uuid:de440e38-081d-428d-a54a-ef5d09a092a7","http://resolver.tudelft.nl/uuid:de440e38-081d-428d-a54a-ef5d09a092a7","Reducing committed emissions of heating towards 2050: Analysis of scenarios for the insulation of buildings and the decarbonisation of electricity generation","Kaandorp, C. (TU Delft Water Resources); Miedema, T. (TU Delft Architecture and the Built Environment); Verhagen, J.D. (TU Delft Water Resources); van de Giesen, N.C. (TU Delft Water Resources); Abraham, E. (TU Delft Water Resources)","","2022","Infrastructure for heat provision in the built environment needs to change remarkably to support lowering carbon emissions and achieving climate mitigation targets before 2050. We propose a computational approach for finding a mix of heat options per neighbourhood that minimises cumulative carbon emissions between 2030 and 2050, referred to as committed emissions, while at the same time adhering to technological constraints at both the household and neighbourhood scales. To establish this approach, we integrated bottom-up heat demand modelling at neighbourhood scale with a mixed-integer non-linear optimisation problem. Nine scenarios with different pathways for the insulation of buildings and the decarbonisation in electricity generation were considered and applied to three neighbourhoods in the city of Amsterdam, the Netherlands. The results show that (i) the committed emissions are ten times lower between 2030 and 2050 in scenarios in which ambitious measures are taken for the insulation of buildings and the decarbonisation in electricity generation, (ii) only in these ‘ambitious scenarios’ low temperature heat systems, such as heat pumps and low temperature heat networks, are optimal solutions for minimising committed emissions, (iii) if less ambitious insulation and decarbonisation measures are taken, high temperature heat options can be part of the heat mix with lowest committed emissions, and (iv) the minimum heat density for low temperature heat networks is not always achieved, creating risks for carbon lock-ins when applying these heat networks. Our results clearly indicate that pathways for the retrofitting of buildings and the decarbonisation in electricity generation need to be taken into account jointly when designing renewable and low-carbon heat systems to optimally reduce carbon emissions towards 2050 and reduce future carbon lock-ins.","Urban heat systems; Committed carbon emissions; Retro-fitting of the building stock; Electrification of heating; Carbon lock-in; Mixed-integer non-linear programming","en","journal article","","","","","","","","","Architecture and the Built Environment","","Water Resources","","",""
"uuid:1c5edb8d-bbb3-45fe-9bef-b4abd82ae9c9","http://resolver.tudelft.nl/uuid:1c5edb8d-bbb3-45fe-9bef-b4abd82ae9c9","Multi-GNSS-Weighted Interpolated Tropospheric Delay to Improve Long-Baseline RTK Positioning","Mirmohammadian, Farinaz (TU Delft Mathematical Geodesy and Positioning); Asgari, Jamal (University of Isfahan); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Amiri Simkooei, A. (TU Delft Optical and Laser Remote Sensing)","","2022","Until now, RTK (real-time kinematic) and NRTK (Network-based RTK) have been the most popular cm-level accurate positioning approaches based on Global Navigation Satellite System (GNSS) signals in real-time. The tropospheric delay is a major source of RTK errors, especially for medium and long baselines. This source of error is difficult to quantify due to its reliance on highly variable atmospheric humidity. In this paper, we use the NRTK approach to estimate double-differenced zenith tropospheric delays alongside ambiguities and positions based on a complete set of multi-GNSS data in a sample 6-station network in Europe. The ZTD files published by IGS were used to validate the estimated ZTDs. The results confirmed a good agreement, with an average Root Mean Squares Error (RMSE) of about 12 mm. Although multiplying the unknowns makes the mathematical model less reliable in correctly fixing integer ambiguities, adding a priori interpolated ZTD as quasi-observations can improve positioning accuracy and Integer Ambiguity Resolution (IAR) performance. In this work, weighted least-squares (WLS) were performed using the interpolation of ZTD values of near reference stations of the IGS network. When using a well-known Kriging interpolation, the weights depend on the semivariogram, and a higher network density is required to obtain the correct covariance function. Hence, we used a simple interpolation strategy, which minimized the impact of altitude variability within the network. Compared to standard RTK where ZTD is assumed to be unknown, this technique improves the positioning accuracy by about 50%. It also increased the success rate for IAR by nearly 1.","tropospheric slant delay; tropospheric zenith delay; double-difference; real-time kinematic; weighted least-squares; interpolation","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:9634fc62-d95f-47f3-b32b-5a6ee93041c1","http://resolver.tudelft.nl/uuid:9634fc62-d95f-47f3-b32b-5a6ee93041c1","A Systematic Literature Review of Predictive Maintenance for Defence Fixed-Wing Aircraft Sustainment and Operations","Scott, Michael J. (Royal Melbourne Institute of Technology University); Verhagen, W.J.C. (Royal Melbourne Institute of Technology University); Bieber, M.T. (TU Delft Air Transport & Operations); Marzocca, Pier (Royal Melbourne Institute of Technology University)","","2022","In recent decades, the increased use of sensor technologies, as well as the increase in digitalisation of aircraft sustainment and operations, have enabled capabilities to detect, diagnose, and predict the health of aircraft structures, systems, and components. Predictive maintenance and closely related concepts, such as prognostics and health management (PHM) have attracted increasing attention from a research perspective, encompassing a growing range of original research papers as well as review papers. When considering the latter, several limitations remain, including a lack of research methodology definition, and a lack of review papers on predictive maintenance which focus on military applications within a defence context. This review paper aims to address these gaps by providing a systematic two-stage review of predictive maintenance focused on a defence domain context, with particular focus on the operations and sustainment of fixed-wing defence aircraft. While defence aircraft share similarities with civil aviation platforms, defence aircraft exhibit significant variation in operations and environment and have different performance objectives and constraints. The review utilises a systematic methodology incorporating bibliometric analysis of the considered domain, as well as text processing and clustering of a set of aligned review papers to position the core topics for subsequent discussion. This discussion highlights state-of-the-art applications and associated success factors in predictive maintenance and decision support, followed by an identification of practical and research challenges. The scope is primarily confined to fixed-wing defence aircraft, including legacy and emerging aircraft platforms. It highlights that challenges in predictive maintenance and PHM for researchers and practitioners alike do not necessarily revolve solely on what can be monitored, but also covers how robust decisions can be made with the quality of data available.","aircraft; decision-making; defence; diagnostics; maintenance; predictive; prognostics; uncertainty","en","journal article","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:1e490f6e-9c1a-414c-95dc-510c0b4d1a91","http://resolver.tudelft.nl/uuid:1e490f6e-9c1a-414c-95dc-510c0b4d1a91","A Generic Framework for Prognostics of Complex Systems","Bieber, M.T. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations)","","2022","In recent years, there has been an enormous increase in the amount of research in the field of prognostics and predictive maintenance for mechanical and electrical systems. Most of the existing approaches are tailored to one specific system. They do not provide a high degree of flexibility and often cannot be adaptively used on different systems. This can lead to years of research, knowledge, and expertise being put in the implementation of prognostics models without the capacity to estimate the remaining useful life of systems, either because of lack of data or data quality or simply because failure behaviour cannot be captured by data-driven models. To overcome this, in this paper we present an adaptive prognostic framework which can be applied to different systems while providing a way to assess whether or not it makes sense to put more time into the development of prognostic models for a system. The framework incorporates steps necessary for prognostics, including data pre-processing, feature extraction and machine learning algorithms for remaining useful life estimation. The framework is applied to two systems: a simulated turbofan engine dataset and an aircraft cooling unit dataset. The results show that the obtained accuracy of the remaining useful life estimates are comparable to what has been achieved in literature and highlight considerations for suitability assessment of systems data towards prognostics.","prognostics and health management; adaptive framework; remaining useful life","en","journal article","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:e6bec754-2916-4374-b207-b86b38c7c9bb","http://resolver.tudelft.nl/uuid:e6bec754-2916-4374-b207-b86b38c7c9bb","From Human Walking to Bipedal Robot Locomotion: Reflex Inspired Compensation on Planned and Unplanned Downsteps","Verhagen, J. (Student TU Delft); Xiong, Xiaobin (California Institute of Technology); Ames, A. D. (California Institute of Technology); Seth, A. (TU Delft Biomechatronics & Human-Machine Control)","","2022","Humans are able to negotiate downstep behaviors-both planned and unplanned-with remarkable agility and ease. The goal of this paper is to systematically study the translation of this human behavior to bipedal walking robots, even if the morphology is inherently different. Concretely, we begin with human data wherein planned and unplanned downsteps are taken. We analyze this data from the perspective of reduced-order modelling of the human, encoding the center of mass (CoM) kinematics and contact forces, which allows for the translation of these behaviors into the corresponding reduced-order model of a bipedal robot. We embed the resulting behaviors into the full-order dynamics of a bipedal robot via nonlinear optimization-based controllers. The end result is the demonstration of planned and unplanned downsteps in simulation on an underactuated walking robot.","","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Biomechatronics & Human-Machine Control","","",""
"uuid:11b69ebd-efd2-4f6e-9849-1e85ebd1838b","http://resolver.tudelft.nl/uuid:11b69ebd-efd2-4f6e-9849-1e85ebd1838b","On-chip distribution of quantum information using traveling phonons","Zivari, A. (TU Delft QN/Groeblacher Lab; Kavli institute of nanoscience Delft); Fiaschi, N. (TU Delft QN/Groeblacher Lab; TU Delft QN/Quantum Nanoscience; Kavli institute of nanoscience Delft); Burgwal, Roel (Eindhoven University of Technology; AMOLF); Verhagen, Ewold (Eindhoven University of Technology; AMOLF); Stockill, Robert (Kavli institute of nanoscience Delft); Groeblacher, S. (TU Delft QN/Quantum Nanoscience; TU Delft QN/Groeblacher Lab)","","2022","Distributing quantum entanglement on a chip is a crucial step toward realizing scalable quantum processors. Using traveling phonons-quantized guided mechanical wave packets-as a medium to transmit quantum states is now gaining substantial attention due to their small size and low propagation speed compared to other carriers, such as electrons or photons. Moreover, phonons are highly promising candidates to connect heterogeneous quantum systems on a chip, such as microwave and optical photons for long-distance transmission of quantum states via optical fibers. Here, we experimentally demonstrate the feasibility of distributing quantum information using phonons by realizing quantum entanglement between two traveling phonons and creating a time-bin-encoded traveling phononic qubit. The mechanical quantum state is generated in an optomechanical cavity and then launched into a phononic waveguide in which it propagates for around 200 micrometers. We further show how the phononic, together with a photonic qubit, can be used to violate a Bell-type inequality.","OA-Fund TU Delft","en","journal article","","","","","","","","","","QN/Quantum Nanoscience","QN/Groeblacher Lab","","",""
"uuid:f8a1adca-4576-4c25-b4e1-2bd2bb45fc60","http://resolver.tudelft.nl/uuid:f8a1adca-4576-4c25-b4e1-2bd2bb45fc60","Improvement of multi-gnss precision and success rate using realistic stochastic model of observations","Mirmohammadian, Farinaz (TU Delft Mathematical Geodesy and Positioning; University of Isfahan); Asgari, Jamal (University of Isfahan); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Amiri Simkooei, A. (TU Delft Optical and Laser Remote Sensing; University of Isfahan)","","2022","With the advancement of multi-constellation and multi-frequency global navigation satellite systems (GNSSs), more observations are available for high precision positioning applications. Although there is a lot of progress in the GNSS world, achieving realistic precision of the solution (neither too optimistic nor too pessimistic) is still an open problem. Weighting among different GNSS systems requires a realistic stochastic model for all observations to achieve the best linear unbiased estimation (BLUE) of unknown parameters in multi-GNSS data processing mode. In addition, the correct integer ambiguity resolution (IAR) becomes crucial in shortening the Time-To-Fix (TTF) in RTK, especially in challenging environmental conditions. In general, it is required to estimate various variances for observation types, consider the correlation between different observables, and compensate for the satellite elevation dependence of the observable precision. Quality control of GNSS signals, such as GPS, GLONASS, Galileo, and BeiDou can be performed by processing a zero or short baseline double difference pseudorange and carrier phase observations using the least-squares variance component estimation (LS-VCE). The efficacy of this method is investigated using real multi-GNSS data sets collected by the Trimble NETR9, SEPT POLARX5, and LEICA GR30 receivers. The results show that the standard deviation of observations depends on the system and the observable type in which a particular receiver could have the best performance. We also note that the estimated variances and correlations among different observations are also dependent on the receiver type. It is because the approaches utilized for the recovery techniques differ from one type of receiver to another kind. The reliability of IAR will improve if a realistic stochastic model is applied in single or multi-GNSS data processing. According to the results, for the data sets considered, a realistic stochastic model can increase the computed empirical success rate to 100% in multi-GNSS as well as a single system. As mentioned previously, the realistic precision of the solution can be achieved with a realistic stochastic model. However, using the estimated stochastic model, in fact, leads to better precision and accuracy for the estimated baseline components, up to 39% in multi-GNSS.","Double-difference; Least-squares variance component estimation; Multi-GNSS observable precision; Variance analysis","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:5e5974a7-4b7e-4cbe-be48-67f928bd2094","http://resolver.tudelft.nl/uuid:5e5974a7-4b7e-4cbe-be48-67f928bd2094","The Correlation Between Wall Shear Stress and Plaque Composition in Advanced Human Carotid Atherosclerosis","Moerman, A. M. (Erasmus MC); Korteland, S. (Erasmus MC); Dilba, K. (Erasmus MC); van Gaalen, K. (Erasmus MC); Poot, D. H.J. (Erasmus MC); van Der Lugt, A. (Erasmus MC); Verhagen, H. J.M. (Erasmus MC); Wentzel, J. J. (Erasmus MC); van Der Steen, A. F.W. (Erasmus MC); Gijsen, F.J.H. (TU Delft Medical Instruments & Bio-Inspired Technology; Erasmus MC); Van der Heiden, K. (Erasmus MC)","","2022","The role of wall shear stress (WSS) in atherosclerotic plaque development is evident, but the relation between WSS and plaque composition in advanced atherosclerosis, potentially resulting in plaque destabilization, is a topic of discussion. Using our previously developed image registration pipeline, we investigated the relation between two WSS metrics, time-averaged WSS (TAWSS) and the oscillatory shear index (OSI), and the local histologically determined plaque composition in a set of advanced human carotid plaques. Our dataset of 11 carotid endarterectomy samples yielded 87 histological cross-sections, which yielded 511 radial bins for analysis. Both TAWSS and OSI values were subdivided into patient-specific low, mid, and high tertiles. This cross-sectional study shows that necrotic core (NC) size and macrophage area are significantly larger in areas exposed to high TAWSS or low OSI. Local TAWSS and OSI tertile values were generally inversely related, as described in the literature, but other combinations were also found. Investigating the relation between plaque vulnerability features and different combinations of TAWSS and OSI tertile values revealed a significantly larger cap thickness in areas exposed to both low TAWSS and low OSI. In conclusion, our study confirmed previous findings, correlating high TAWSS to larger macrophage areas and necrotic core sizes. In addition, our study demonstrated new relations, correlating low OSI to larger macrophage areas, and a combination of low TAWSS and low OSI to larger cap thickness.","atherosclerosis; image registration pipeline; MRI; oscillatory shear index; plaque composition; vulnerable plaque; wall shear stress","en","journal article","","","","","","","","","","","Medical Instruments & Bio-Inspired Technology","","",""
"uuid:7ba242db-b650-4402-904e-3704e0ce725b","http://resolver.tudelft.nl/uuid:7ba242db-b650-4402-904e-3704e0ce725b","Transitioning to Low-Carbon Residential Heating: The Impacts of Material-Related Emissions","Verhagen, Teun Johannes (Universiteit Leiden); Cetinay, Hale Iyicil (Universiteit Leiden); Van Der Voet, Ester (Universiteit Leiden); Sprecher, B. (TU Delft Design for Sustainability)","","2022","To achieve climate neutrality, future urban heating systems will need to use a variety of low-carbon heating technologies. The transition toward low-carbon heating technologies necessitates a complete restructuring of the heating system, with significant associated material requirements. However, little research has been done into the quantity and environmental impact of the required materials for this system change. We analyzed the material demand and the environmental impact of the transition toward low-carbon heating in the Netherlands across three scenarios based on the local availability and capacity for sources of low-carbon heat. A wide range of materials are included, covering aggregates, construction materials, metals, plastics, and critical materials. We find that while the Dutch policy goal of reducing GHG emissions by 90% before 2050 can be achieved if only direct emissions from the heating system are considered, this is no longer the case when the cradle-to-gate emissions from the additional materials, especially insulation materials, are taken into account. The implementation of these technologies will require 59-63 megatons of materials in the period of 2021-2050, leading to a maximum reduction of 62%.","cradle-to-gate emissions; heating technologies; low-carbon; material impact","en","journal article","","","","","","","","","","","Design for Sustainability","","",""
"uuid:19159f70-0d0e-4340-ab90-5d9daa402e73","http://resolver.tudelft.nl/uuid:19159f70-0d0e-4340-ab90-5d9daa402e73","Interplay of Leakage Radiation and Protection in Topological Photonic Crystal Cavities","Barczyk, R.T. (AMOLF); Parappurath, Nikhil (AMOLF); Arora, S. (TU Delft QN/Kuipers Lab; Kavli institute of nanoscience Delft); Bauer, T.A. (TU Delft QN/Kuipers Lab; Kavli institute of nanoscience Delft); Kuipers, L. (Kavli institute of nanoscience Delft); Verhagen, Ewold (Eindhoven University of Technology)","","2022","The introduction of topological concepts to the design of photonic crystal cavities holds great promise for applications in integrated photonics due to the prospect of topological protection. This study examines the signatures of topological light confinement in the leakage radiation of 2D topological photonic crystal cavities. The cavities are implemented in an all-dielectric platform that features the photonic quantum spin Hall effect at telecom wavelengths and supports helical edge states that are weakly coupled to the radiation continuum. The modes of resonators scaling down to single point defects in the surrounding bulk lattice are characterized via spectral position and multipolar nature of the eigenstates. The mode profiles in real and momentum space are mapped using far-field imaging and Fourier-spectropolarimetry, revealing how certain properties of the cavity modes reflect on their origin in the topological bandstructure. This includes band-inversion-induced confinement and inverted scaling of mode spectra for trivial and topological defect cavities. Furthermore, hallmarks of topological protection in the loss rates are demonstrated, which are largely unaffected by cavity shape and size. The results constitute an important step toward the use of radiative topological cavities for on-chip confinement of light, control of emitted wave fronts, and enhancement of light–matter interactions.","cavities; Fourier spectroscopy; photonic crystals; quantum spin Hall effect; topology","en","journal article","","","","","","","","","","","QN/Kuipers Lab","","",""
"uuid:5ef5b7a5-d835-4273-a005-8d34e455ed6a","http://resolver.tudelft.nl/uuid:5ef5b7a5-d835-4273-a005-8d34e455ed6a","Breakdown of Spin-to-Helicity Locking at the Nanoscale in Topological Photonic Crystal Edge States","Arora, S. (TU Delft QN/Kuipers Lab; Kavli institute of nanoscience Delft); Bauer, T.A. (TU Delft QN/Kuipers Lab; Kavli institute of nanoscience Delft); Parappurath, N. (AMOLF); Barczyk, R.T. (AMOLF); Verhagen, E. (AMOLF); Kuipers, L. (TU Delft QN/Quantum Nanoscience)","","2022","We measure the local near-field spin in topological edge state waveguides that emulate the quantum spin Hall effect. We reveal a highly structured spin density distribution that is not linked to a unique pseudospin value. From experimental near-field real-space maps and numerical calculations, we confirm that this local structure is essential in understanding the properties of optical edge states and light-matter interactions. The global spin is reduced by a factor of 30 in the near field and, for certain frequencies, flipped compared to the pseudospin measured in the far field. We experimentally reveal the influence of higher-order Bloch harmonics in spin inhomogeneity, leading to a breakdown in the coupling between local helicity and global spin.","","en","journal article","","","","","","","","","","QN/Quantum Nanoscience","QN/Kuipers Lab","","",""
"uuid:41d9fe21-465f-444d-91ff-2508f50d3fe5","http://resolver.tudelft.nl/uuid:41d9fe21-465f-444d-91ff-2508f50d3fe5","Predicting Metabolic Adaptation Under Dynamic Substrate Conditions Using a Resource-Dependent Kinetic Model: A Case Study Using Saccharomyces cerevisiae","Verhagen, K.J.A. (TU Delft BT/Industriele Microbiologie); Eerden, S. A. (Student TU Delft); Sikkema, B. J. (Student TU Delft); Wahl, S.A. (TU Delft BT/Industriele Microbiologie; Friedrich-Alexander-Universität Erlangen-Nürnberg)","","2022","Exposed to changes in their environment, microorganisms will adapt their phenotype, including metabolism, to ensure survival. To understand the adaptation principles, resource allocation-based approaches were successfully applied to predict an optimal proteome allocation under (quasi) steady-state conditions. Nevertheless, for a general, dynamic environment, enzyme kinetics will have to be taken into account which was not included in the linear resource allocation models. To this end, a resource-dependent kinetic model was developed and applied to the model organism Saccharomyces cerevisiae by combining published kinetic models and calibrating the model parameters to published proteomics and fluxomics datasets. Using this approach, we were able to predict specific proteomes at different dilution rates under chemostat conditions. Interestingly, the approach suggests that the occurrence of aerobic fermentation (Crabtree effect) in S. cerevisiae is not caused by space limitation in the total proteome but rather an effect of constraints on the mitochondria. When exposing the approach to repetitive, dynamic substrate conditions, the proteome space was allocated differently. Less space was predicted to be available for non-essential enzymes (reserve space). This could indicate that the perceived “overcapacity” present in experimentally measured proteomes may very likely serve a purpose in increasing the robustness of a cell to dynamic conditions, especially an increase of proteome space for the growth reaction as well as of the trehalose cycle that was shown to be essential in providing robustness upon stronger substrate perturbations. The model predictions of proteome adaptation to dynamic conditions were additionally evaluated against respective experimentally measured proteomes, which highlighted the model’s ability to accurately predict major proteome adaptation trends. This proof of principle for the approach can be extended to production organisms and applied for both understanding metabolic adaptation and improving industrial process design.","Crabtree effect; dynamic conditions; feast/famine; kinetic modeling; proteome adaptation; resource allocation; Saccharomyces cerevisiae","en","journal article","","","","","","","","","","","BT/Industriele Microbiologie","","",""
"uuid:5344f9ed-8666-4b9d-b934-1f0e1ab0bb7e","http://resolver.tudelft.nl/uuid:5344f9ed-8666-4b9d-b934-1f0e1ab0bb7e","Topological Protection in Radiative Photonic Crystal Cavities","Barczyk, R.T. (AMOLF); Parappurath, N. (AMOLF); Arora, S. (TU Delft QN/Kuipers Lab; Kavli institute of nanoscience Delft); Bauer, T.A. (TU Delft QN/Kuipers Lab; Kavli institute of nanoscience Delft); Kuipers, L. (TU Delft QN/Quantum Nanoscience; Kavli institute of nanoscience Delft); Verhagen, E. (AMOLF)","","2022","We study the signatures of topological light confinement in the leakage radiation of two-dimensional topological photonic crystal cavities that feature the quantum spin Hall effect at telecom wavelengths. The mode profiles in real and momentum space are retrieved using far field imaging and Fourier spectropolarimetry. We examine the scaling behavior of mode spectra, observe band-inversion-induced confinement, and demonstrate hallmarks of topological protection in the loss rates, which are largely unaffected by cavity shape and size.","","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","QN/Quantum Nanoscience","QN/Kuipers Lab","","",""
"uuid:65926a98-9332-4631-83ab-9550352f95c4","http://resolver.tudelft.nl/uuid:65926a98-9332-4631-83ab-9550352f95c4","A novel decision support system for optimizing aircraft maintenance check schedule and task allocation","Deng, Q. (TU Delft Air Transport & Operations); Santos, Bruno F. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations; Royal Melbourne Institute of Technology University)","","2021","Modern aircraft have thousands of parts, systems, and components that need to be recurrently inspected or replaced. To keep the fleet airworthy, maintenance planners have to schedule the maintenance checks for each aircraft and the associated tasks. In practice, these two complex problems are solved following the experience of planners, resulting in sub-efficient solutions. This paper presents the first decision support system (DSS) developed for optimizing both aircraft maintenance check schedule and task allocation. The DSS integrates aircraft maintenance check scheduling, task allocation to each maintenance check, and shift planning in the same framework. The practical relevance of the DSS is illustrated through three test cases. The results show that the DSS can be used not only to optimize maintenance plans but also to study future maintenance policies. The results reveal substantial improvements in all key performance indicators compared with the planning approach followed by a partner airline.","Decision Support; Aircraft Maintenance; Task Allocation; Dynamic Programming; Bin Packing; Aircraft maintenance; Task allocation; Bin packing; Dynamic programming; Decision support","en","journal article","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:5fa21221-a5a2-4215-b288-9288d0f03a8c","http://resolver.tudelft.nl/uuid:5fa21221-a5a2-4215-b288-9288d0f03a8c","An Adaptive Framework For Remaining Useful Life Predictions Of Aircraft Systems","Bieber, M.T. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (Royal Melbourne Institute of Technology University); Santos, Bruno F. (TU Delft Air Transport & Operations)","","2021","Prognostics for condition-based maintenance does not only consist of prognostic algorithms but also involves steps such as data pre-processing, feature extraction, and feature selection, all of which contribute to the quality of the remaining useful life estimation. This process requires a lot of expertise and technical knowledge, which for many application systems is neither feasible nor affordable. In this paper, therefore, we present a generic framework with the capability to automatically choose the optimal settings for prognostics, given a specific data set. The framework consists of two phases. In the first one, a genetic algorithm optimizes the choice of methodologies together with hyperparameter settings for the feature extraction, feature selection, and prognostic algorithm selection. In the second phase, the identified settings define the prognostic setup, which in turn is used to train the model for remaining useful life estimation. This framework is then applied to a simulated aircraft engine data set. The first results show that remaining useful life estimates are comparable to the values obtained using established prognostic algorithms on the same data set. In addition, the framework is applied to estimate the remaining useful life of real aircraft systems. Results on underlying data sets suggest that the generic prognostic framework can easily and quickly be adapted to various systems. In further consequence, such a generic framework offers a way to assess the feasibility of prognostics for systems depending on the underlying existing data sets.","","en","conference paper","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:a9484041-7559-4cbd-ac32-eafda01f0bcd","http://resolver.tudelft.nl/uuid:a9484041-7559-4cbd-ac32-eafda01f0bcd","Vectorial integer bootstrapping: flexible integer estimation with application to GNSS","Teunissen, P.J.G. (TU Delft Mathematical Geodesy and Positioning; Curtin University; University of Melbourne); Massarweh, L. (TU Delft Mathematical Geodesy and Positioning); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning)","","2021","In this contribution, we extend the principle of integer bootstrapping (IB) to a vectorial form (VIB). The mathematical definition of the class of VIB-estimators is introduced together with their pull-in regions and other properties such as probability bounds and success rate approximations. The vectorial formulation allows sequential block-by-block processing of the ambiguities based on a user-chosen partitioning. In this way, flexibility is created, where for specific choices of partitioning, tailored VIB-estimators can be designed. This wide range of possibilities is discussed, supported by numerical simulations and analytical examples. Further guidelines are provided, as well as the possible extension to other classes of estimators.","Ambiguity success rate; GNSS; Integer ambiguity resolution; Integer least-squares (ILS); Pull-in region; Vectorial integer bootstrapping (VIB); Z-transformation","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:19077cdf-3246-4f7e-bd69-c0bfb4fd8a82","http://resolver.tudelft.nl/uuid:19077cdf-3246-4f7e-bd69-c0bfb4fd8a82","Making it Concrete: Analysing the Role of Concrete Plants’ Locations for Circular City Policy Goals","Van den Berghe, K.B.J. (TU Delft Urban Development Management); Verhagen, Teun (Universiteit Leiden)","","2021","Increasingly, space for remanufacturing is seen as the most valuable resource to achieve circular economy (CE) policy goals, in particular for cities. However, in many cities, industrial urban areas are increasingly subject of – mostly circular designed - residential redevelopment. The proposition of this paper is that these diminishing industrial areas host, at least potentially, essential functions necessary to “close the material loop.” The reason why policy makers neglect the necessity of remanufacturing capacity, is because it is difficult to pinpoint the “ideal” geography of a circular loop. Most (circular) products can be transported limitless, thus their remanufacturing functions can be located around the world. But what if a critical material cannot be transported limitless and has circular potential? Therefore, this paper focusses on concrete for two reasons. First, concrete is by far the most abundant material in urban areas. Second, newly/circular made fluid concrete can only be transported for a limited time and distance. The hypothesis of this paper is that concrete plants are and will become essential for circular cities. Subsequently, we focus on the Dutch city of The Hague and combine a Material Flow Analysis with the locations of the concrete resupply chain. Our results show that potentially The Hague has a 100% circular concrete chain, but the importance of its concrete plant is (implicitly) neglected. We conclude that The Hague is illustrative for the problem of many circular cities that are without (implicitly) taking into account the whole circular resupply chain, jeopardized today a future urban CE.","(re)supply chain; circular city; circular washing; concrete; urban metabolism","en","journal article","","","","","","","","","","","Urban Development Management","","",""
"uuid:f22df3d9-275c-4fad-a373-fdefb7f192fa","http://resolver.tudelft.nl/uuid:f22df3d9-275c-4fad-a373-fdefb7f192fa","Operational planning of WEF infrastructure: quantifying the value of information sharing and cooperation in the Eastern Nile basin","Verhagen, J.D. (TU Delft Water Resources); van der Zaag, P. (TU Delft Water Resources); Abraham, E. (TU Delft Water Resources)","","2021","Integrating the planning of a multi-reservoir system in nexus with agricultural and electricity infrastructure could alleviate security concerns for these resources in regions where demand is growing while water and land scarcity are exacerbated by climate change and anthropogenic pressures. This study focuses on the benefits of resource integration and cooperation in the Eastern Nile basin. To overcome common limitations of equilibrium and soft-linked partial equilibrium models (e.g. high levels of spatial aggregation, non-insightful cooperation scenarios and a lack of heterogeneity), we propose a regional hard-linked WEF-nexus model that explicitly represents resource connectivity networks for water and electricity, and describes heterogeneity in resource availability, production potentials and physical constraints. Using a non-linear operational process, we optimise reservoir operations, water allocations, cropping patterns, electricity mixes and trade quantities on a monthly time-step over multiple years in a receding horizon fashion to maximize economic benefits for each country and regionally. This iterative implementation allows the modelling of operational changes as feedback against exogenous climate disturbances and enables information exchange between upstream-downstream countries. Thus, we describe four different levels of transboundary cooperation with their corresponding constraints and policy objectives. Compared to the reference scenario of unilateral planning, our results indicate an increase in regional economic returns for scenarios in which river flow information is shared between countries (+9%), river flow and trade information are shared (+10%) and WEF resources are coordinated regionally (+15%). These increased returns successively come from an increase in the effectiveness of agricultural water consumption, especially in Sudan, a change in trade patterns for agricultural products and a shift in cropping patterns. These findings underscore the importance of adequate representations of spatial and temporal heterogeneity of resources and their connectivity, as well as the need for a more diverse set of collaboration scenarios to facilitate planning in transboundary river systems.","Eastern Nile basin; MPC; WEF nexus; hydro-economics; optimisation; self-sufficiency; transboundary cooperation","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:b977743a-d7e7-4402-8ec4-ab490734cd62","http://resolver.tudelft.nl/uuid:b977743a-d7e7-4402-8ec4-ab490734cd62","Morphometric and Mechanical Analyses of Calcifications and Fibrous Plaque Tissue in Carotid Arteries for Plaque Rupture Risk Assessment","Gijsen, F.J.H. (TU Delft ChemE/Transport Phenomena; Erasmus MC); Vis, Bas (Erasmus MC; Student TU Delft); Barrett, Hilary E. (Erasmus MC); Zadpoor, A.A. (TU Delft Biomaterials & Tissue Biomechanics); Verhagen, Hence J. (Erasmus MC); Bos, Daniel (Erasmus MC); van der Steen, A.F.W. (Erasmus MC); Akyildiz, A.C. (TU Delft Medical Instruments & Bio-Inspired Technology; Erasmus MC)","","2021","Objective: Atherosclerotic plaque rupture in carotid arteries is a major source of cerebrovascular events. Calcifications are highly prevalent in carotid plaques, but their role in plaque rupture remains poorly understood. This work studied the morphometric features of calcifications in carotid plaques and their effect on the stress distribution in the fibrous plaque tissue at the calcification interface, as a potential source of plaque rupture and clinical events. Methods: A comprehensive morphometric analysis of 65 histology cross-sections from 16 carotid plaques was performed to identify the morphology (size and shape) and location of plaque calcifications, and the fibrous-tissue fiber organization around them. Calcification-specific finite element models were constructed to examine the fibrous plaque tissue stresses at the calcification interface. Statistical correlation analysis was performed to elucidate the impact of calcification morphology and fibrous tissue organization on interface stresses. Results: Hundred-seventy-one calcifications were identified on the histology cross-sections, which showed great variation in morphology. Four distinct patterns of fiber organization in the plaque tissue were observed around the calcification. They were termed as attached, pushed-aside, encircling and random patterns. The stress analyses showed that calcifications are correlated with high interface stresses, which might be comparable to or even above the plaque strength. The stress levels depended on the calcification morphology and fiber organization. Thicker calcification with a circumferential slender shape, located close to the lumen were correlated most prominently to high interface stresses. Conclusion: Depending on its morphology and the fiber organization around it, a calcification in an atherosclerotic plaque can act as a stress riser and cause high interface stresses. Significance: This study demonstrated the potential of calcifications in atherosclerotic plaques to cause elevated stresses in plaque tissue and provided a biomechanical explanation for the histopathological findings of calcification-associated plaque rupture.","Atherosclerosis; Carotid arteries; Histopathology; Morphology; Optical fiber dispersion; Organizations; Stress","en","journal article","","","","","","Accepted Author Manuscript","","","","","ChemE/Transport Phenomena","","",""
"uuid:0fa5cc24-569e-4727-b568-585607f219d0","http://resolver.tudelft.nl/uuid:0fa5cc24-569e-4727-b568-585607f219d0","Implementing Business Models Into Operations: Impact of Business Model Implementation on Performance","Verhagen, M.P. (Student TU Delft); de Reuver, Mark (TU Delft Information and Communication Technology); Bouwman, W.A.G.A. (TU Delft Information and Communication Technology)","","2021","Business models (BMs) help firms to translate abstract strategic decisions into their daily operations. Because BMs mediate between strategy and operations, BM innovation involves both high-level strategic experiments and low-level implementation into operations and technologies. However, most existing empirical studies regarding BM innovation focus exclusively on strategic management and marketing theory. This article examines whether the performance implications of BM experimentation are mediated by the time and effort spent on implementing BMs into operating models and enterprise architectures. We adopt an empirical approach, by analyzing the results of a large-scale, representative survey among European small and medium-sized enterprises (SMEs). In line with the existing literature, the research confirms that spending time and effort experimenting with new BMs has a positive impact on the firm performance. An important new finding is that impact is in part mediated by BM implementation (i.e., translating new BMs into operating models and enterprise architectures). This article provides empirical support for the argument that BM innovation is not just a matter of strategic thinking and experimenting with BM components and BM architecture, but that is also involve aligning BMs to operations and enterprise architectures. Our findings call for future research into the process of BM innovation from a business modeling, an enterprise architecting and engineering management perspective, with a focus on information exchange, business processes, and supporting IT applications and infrastructure.","Business models (BMs); business model innovation (BMI); enterprise architecture (EA); operating model (OM)","en","journal article","","","","","","","","","","","Information and Communication Technology","","",""
"uuid:995f6665-cd5a-403e-903a-077a402bb435","http://resolver.tudelft.nl/uuid:995f6665-cd5a-403e-903a-077a402bb435","Flight-Test Evaluation of Integer Ambiguity Resolution Enabled PPP","Ma, H. (TU Delft Mathematical Geodesy and Positioning); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Psychas, D.V. (TU Delft Mathematical Geodesy and Positioning; Fugro); Monico, João Francisco Galera (São Paulo State University); Marques, Haroldo Antonio (Instituto Militar de Engenharia)","","2021","The technology of integer ambiguity resolution-enabled precise-point-positioning (also referred to as PPP-AR) has been proven capable of providing comparable accuracy, efficiency, and productivity to long-baseline real-time kinematic positioning (RTK) during the last decade. Commercial PPP-AR services have been provided by different institutions and companies and have been widely used in geodetic missions. However, the usage and research of the PPP-AR mostly concentrated on nonaviation applications, e.g., vehicle navigation, surveying, and mapping, and monitoring crustal motions. Few of them focused on fixing the ambiguities during an aircraft flight. In this contribution, we implemented the PPP-AR technique for the first time in an airplane flight test to investigate how much the fixed ambiguities could contribute to airplane positioning solutions in challenging circumstances, including high velocity and severe maneuvers. We first looked into the influences of the tropospheric delay on the positioning and ambiguity solutions because the height of the airplane may dramatically change within a narrow time span, and thus, a proper constraint of this parameter was crucial for the computation of the tropospheric effects. Then, how to fix the ambiguities successfully and reliably in challenging circumstances was discussed. Finally, the airplane data was processed in 15 and 1s intervals with ambiguity float and fixed solutions under different configurations to illustrate in which condition and to what extent the fixed ambiguities can improve the airplane positioning accuracy.","Airplane navigation; Global navigation satellite system (GNSS); Integer ambiguity resolution; PPP-AR; Precise point positioning (PPP)","en","journal article","","","","","","Accepted author manuscript","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:7a10f769-ec54-416f-bda5-8d7180eb23a0","http://resolver.tudelft.nl/uuid:7a10f769-ec54-416f-bda5-8d7180eb23a0","A multi-frequency galileo ppp-rtk convergence analysis with an emphasis on the role of frequency spacing","Psychas, D.V. (TU Delft Mathematical Geodesy and Positioning); Teunissen, P.J.G. (TU Delft Mathematical Geodesy and Positioning; Curtin University; University of Melbourne); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning)","","2021","The single-receiver integer ambiguity resolution-enabled variant of precise point positioning (PPP), namely PPP-RTK, has proven to be crucial in reducing the long convergence time of PPP solutions through the recovery of the integerness of the user-ambiguities. The proliferation of global navigation satellite systems (GNSS) supports various improvements in this regard through the availability of more satellites and frequencies. The increased availability of the Galileo E6 signal from GNSS receivers paves the way for speeding up integer ambiguity resolution, as more frequencies provide for a stronger model. In this contribution, the Galileo-based PPP-RTK ambiguity resolution and positioning convergence capabilities are studied and numerically demonstrated as a function of the number and spacing of frequencies, aiming to shed light on which frequencies should be used to obtain optimal performance. Through a formal analysis, we provide insight into the pivotal role of frequency separation in ambiguity resolution. Using real Galileo data on up to five frequencies and our estimated PPP-RTK corrections, representative kinematic user convergence results with partial ambiguity resolution are presented and discussed. Compared to the achieved performance of dual-frequency fixed solutions, it is found that the contribution of multi-frequency observations is significant and largely driven by frequency separation. When using all five available frequencies, it is shown that the kinematic user can achieve a sub-decimeter level convergence in 15.0 min (90% percentile). In our analysis, we also show to what extent the provision of the estimable satellite code biases as standard PPP-RTK corrections accelerates convergence. Finally, we numerically demonstrate that, when integrated with GPS, the kinematic user solution achieves convergence in 3.0 and 5.0 min on average and at 90%, respectively, in the presence of ionospheric delays, thereby indicating the single-receiver user’s fast-convergence capabilities.","Frequency spacing; Galileo; Integer ambiguity resolution (IAR); Multi-frequency; Precise point positioning (PPP); Satellite code biases","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:be3431ab-5518-41de-bce4-3ea2be9e6168","http://resolver.tudelft.nl/uuid:be3431ab-5518-41de-bce4-3ea2be9e6168","The effect of function-based and voxel-based tropospheric tomography techniques on the GNSS positioning accuracy","Haji Aghajany, S. (TU Delft Mathematical Geodesy and Positioning; K.N. Toosi University of Technology); Amerian, Yazdan (K.N. Toosi University of Technology); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Rohm, Witold (Wroclaw University of Environmental and Life Sciences); Schuh, Harald (VolcanoTectonics Junior Research Group; Technical University of Berlin)","","2021","Tropospheric wet delay, the main source of which is water vapor, is one of the major factors affecting the accuracy of positioning techniques using microwave. Tropospheric tomography is a powerful method to reconstruct the water vapor content in four-dimensional (4D) space. This paper studies the effect of using function-based and voxel-based tropospheric tomography methods on the positioning accuracy. This examination is performed on the static and kinematic positioning modes using Global Navigation Satellite Systems (GNSS) stations under different weather conditions. After validating the results of tomography methods using radiosonde observations, the tomography-based positioning solutions, including function-based and voxel-based approaches, are compared with the positions obtained using tropospheric models. The results of two GPS stations show that the accuracy increases when applying tomography approaches. The function-based tomography is able to increase the accuracy of the up component of the static and kinematic modes by about 0.42 and 0.79 cm, respectively, compared to the voxel-based method. In addition, the use of the function-based tropospheric tomography can decrease the convergence time of the kinematic Precise Point Positioning (PPP) solution.","Function-based; GNSS; Precise Point Positioning; Tropospheric tomography; Voxel-based","en","journal article","","","","","","","","2022-06-24","","","Mathematical Geodesy and Positioning","","",""
"uuid:bdc0c89f-ca60-41c0-9186-2c5e619e04a3","http://resolver.tudelft.nl/uuid:bdc0c89f-ca60-41c0-9186-2c5e619e04a3","SPECT/CT imaging of inflammation and calcification in human carotid atherosclerosis to identify the plaque at risk of rupture","Van der Heiden, K. (Erasmus MC); Barrett, H. E. (Erasmus MC); van Gaalen, K.C. (Erasmus MC); Krenning, B. J. (Erasmus MC); Beekman, F.J. (TU Delft RST/Biomedical Imaging; University Medical Center Utrecht; MILabs B.V.); Verhagen, H. J.M. (Erasmus MC); Norenberg, J. P. (University of New Mexico); de Jong, M. (Erasmus MC); Gijsen, F.J.H. (Erasmus MC)","","2021","Background: Calcification and inflammation are atherosclerotic plaque compositional biomarkers that have both been linked to stroke risk. The aim of this study was to evaluate their co-existing prevalence in human carotid plaques with respect to plaque phenotype to determine the value of hybrid imaging for the detection of these biomarkers. Methods: Human carotid plaque segments, obtained from endarterectomy, were incubated in [111In]In-DOTA-butylamino-NorBIRT ([111In]In-Danbirt), targeting Leukocyte Function-associated Antigen-1 (LFA-1) on leukocytes. By performing SPECT/CT, both inflammation from DANBIRT uptake and calcification from CT imaging were assessed. Plaque phenotype was classified using histology. Results: On a total plaque level, comparable levels of calcification volume existed with different degrees of inflammation and vice versa. On a segment level, an inverse relationship between calcification volume and inflammation was evident in highly calcified segments, which classify as fibrocalcific, stable plaque segments. In contrast, segments with little or no calcification presented with a moderate to high degree of inflammation, often coinciding with the more dangerous fibrous cap atheroma phenotype. Conclusion: Calcification imaging alone can only accurately identify highly calcified, stable, fibrocalcific plaques. To identify high-risk plaques, with little or no calcification, hybrid imaging of calcification and inflammation could provide diagnostic benefit.","calcification; human carotid plaque; inflammation; SPECT/CT; vulnerable plaque","en","journal article","","","","","","","","","","","RST/Biomedical Imaging","","",""
"uuid:e0a18b3a-b81a-457a-a877-47b0e72a9b33","http://resolver.tudelft.nl/uuid:e0a18b3a-b81a-457a-a877-47b0e72a9b33","A web-based decision support system for aircraft dispatch and maintenance","Koornneef, H. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (Royal Melbourne Institute of Technology University); Curran, R. (TU Delft Air Transport & Operations)","","2021","Aircraft dispatch involves determining the optimal dispatch option when an aircraft experiences an unexpected failure. Currently, maintenance technicians at the apron have limited access to support information and finding the right information in extensive maintenance manuals is a time-consuming task, often leading to technically induced delays. This paper introduces a novel web-based prototype decision support system to aid technicians during aircraft dispatch decision-making and subsequent maintenance execution. A system architecture for real-time dispatch decision support is established and implemented. The developed system is evaluated through a case study in an operational environment by licensed maintenance technicians. The system fully automates information retrieval from multiple data sources, performs alternative identification and evaluation for a given fault message, and provides the technician with on-site access to relevant information, including the related maintenance tasks. The case study indicates a potential time saving of up to 98% per dispatch decision. Moreover, it enables digitalization of the—currently mostly paper-based—dispatch decision process, thereby reducing logistics and paper waste. The prototype is the first to provide operational decision support in the aircraft maintenance domain and addresses the lack of correlation between theory and practice often found in decision support systems research by providing a representative case study. The developed custom parser for SGML-based documents enables efficient identification and extraction of relevant information, vastly contributing to the overall reduction of the decision time.","Aircraft maintenance; Data integration; Decision support; Dispatch assessment; Information retrieval; Mobile tools","en","journal article","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:21d510d6-a9b0-499c-9a58-82dd11dd62b2","http://resolver.tudelft.nl/uuid:21d510d6-a9b0-499c-9a58-82dd11dd62b2","Prediction of changes in seafloor depths based on time series of bathymetry observations: Dutch north sea case","Toodesh, R. (TU Delft Mathematical Geodesy and Positioning); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Dagla, Anastasia (Student TU Delft)","","2021","Guaranteeing safety of navigation within the Netherlands Continental Shelf (NCS), while efficiently using its ocean mapping resources, is a key task of Netherlands Hydrographic Service (NLHS) and Rijkswaterstaat (RWS). Resurvey frequencies depend on seafloor dynamics and the aim of this research is to model the seafloor dynamics to predict changes in seafloor depth that would require resurveying. Characterisation of the seafloor dynamics is based on available time series of bathymetry data obtained from the acoustic remote sensing method of both single-beam echosounding (SBES) and multibeam echosounding (MBES). This time series is used to define a library of mathematical models describing the seafloor dynamics in relation to spatial and temporal changes in depth. An adaptive, functional model selection procedure is developed using a nodal analysis (0D) approach, based on statistical hypothesis testing using a combination of the Overall Model Test (OMT) statistic and Generalised Likelihood Ratio Test (GLRT). This approach ensures that each model has an equal chance of being selected, when more than one hypothesis is plausible for areas that exhibit varying seafloor dynamics. This ensures a more flexible and rigorous decision on the choice of the nominal model assumption. The addition of piecewise linear models to the library offers another characterisation of the trends in the nodal time series. This has led to an optimised model selection procedure and parameterisation of each nodal time series, which is used for the spatial and temporal predictions of the changes in the depths and associated uncertainties. The model selection results show that the models can detect the changes in the seafloor depths with spatial consistency and similarity, particularly in the shoaling areas where tidal sandwaves are present. The predicted changes in depths and uncertainties are translated into a probability risk-alert map by evaluating the probabilities of an indicator variable exceeding a certain decision threshold. This research can further support the decision-making process when optimising resurvey frequencies.","Bathymetry; Decision-making; Prediction; Sandwaves; Statistical hypothesis testing; Time series","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:1c4f8e69-f3d7-46b4-b161-b63dcb102793","http://resolver.tudelft.nl/uuid:1c4f8e69-f3d7-46b4-b161-b63dcb102793","Data-Driven Prognostics Incorporating Environmental Factors for Aircraft Maintenance","Bieber, M.T. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations; Royal Melbourne Institute of Technology University); Santos, Bruno F. (TU Delft Air Transport & Operations)","","2021","During flights aircraft continuously collect data regarding operations, health status and system condition. Data-driven approaches typically applied to system specific sensor data provide a way to predict failures of aircraft systems. However, it is believed that some systems deteriorate faster when subjected to particular environmental conditions, such as humidity or dust. In this study, we consider an aircraft system which is suspected to experience degradation due to humidity during ground operations. We apply a Random Forest approach to sensor data only and a combination of sensor data and environmental data from airports to estimate the system's remaining useful life. To our knowledge this is the first paper addressing the problem of integrating environmental data in prognostics for aircraft systems using raw sensor data. The method is validated on a data set provided by an airline that includes the per-second sensor data of 11 different sensors for roughly 12,300 flights, as well as 15 removals. Meteorological data for airports worldwide is obtained from the Meteorological Aerodrome Reports database. The results show that incorporating environmental data in prognostics has a potential towards more accurate prediction models.","condition-based maintenance; prognostics; aircraft maintenance; RUL; environmental data","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2022-05-31","","","Air Transport & Operations","","",""
"uuid:ca8feff6-e82d-4394-9186-fcb8d3a5bb25","http://resolver.tudelft.nl/uuid:ca8feff6-e82d-4394-9186-fcb8d3a5bb25","Influence of the inhomogeneous troposphere on GNSS positioning and integer ambiguity resolution","Ma, H. (TU Delft Mathematical Geodesy and Positioning; Wuhan University); Psychas, D.V. (TU Delft Mathematical Geodesy and Positioning; Fugro); Xing, Xuhuang (Hainan Meteorological Service Center); Zhao, Qile (Wuhan University); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Liu, Xianglin (Fugro)","","2021","The tropospheric delay is one of many error sources that affect the Global Navigation Satellite System (GNSS) positioning solutions. The widely used troposphere models assume a homogeneous atmosphere so that only the zenith delay needs to be determined and is mapped through an elevation-dependent mapping function. This procedure is to reduce the computational burden and keep the positioning model full-rank. However, this assumption fails for a realistic description of the troposphere, which is always asymmetrical at a certain elevation angle, especially during a weather event when the weather conditions are very complex. These imperfectly modelled tropospheric delays may influence the positioning accuracy and integer ambiguity resolution performance. In this case, this contribution aims to investigate the effects of the model errors due to the asymmetrical troposphere on GNSS estimations. The Numerical Weather Prediction (NWP) model is applied to generate the actual ray-tracing tropospheric delay in Western Europe, and the tropospheric model errors are calculated in a normal weather condition and a weather event condition by comparing the slant delay calculated from the NWP model and the mapping function. Case studies on the same GNSS station are conducted in two weather conditions: a normal troposphere condition and a weather event with heavy rainfall. The results based on the case studies show that the troposphere in the normal weather condition is nearly homogeneous that the azimuthal-dependent discrepancies of the tropospheric delay are less than 1cm at a very low elevation angle; meanwhile, the discrepancies between different azimuthal angles can reach to more than 25cm in the weather event. A single-frequency Single Point Positioning (SPP) model and a Precise Point Positioning (PPP) model that preserves the integer property of ambiguity are chosen for studying the estimation biases caused by the troposphere model errors. It turns out that almost all horizontal positioning biases of SPP and PPP are less than 1cm in the normal weather condition; however, the scales of the horizontal and 3D biases are concentrated in 1 to 10cm in the weather event for these two models. This contribution also contains the study of the actual integer ambiguity resolution success rate in the presence of the tropospheric model errors by applying the Monte Carlo simulation, and the success rates of PPP in the normal weather condition are consistent with the theoretical values calculated with the ideal troposphere which is totally symmetrical. However, the actual success rates in the weather event are extremely low at some epochs due to the tropospheric model errors, which means that wrong fixing may occur since the theoretical values cannot take into account these model errors. Note that the horizontal tropospheric gradients are not involved in the processing, which means that an optimistic performance might be expected if the gradients are considered.","GNSS; Integer ambiguity resolution; Model errors; Monte Carlo simulation; PPP; PPP-AR; Tropospheric delay","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:b0149a07-ca67-4ad1-84a5-7a37b981bc4e","http://resolver.tudelft.nl/uuid:b0149a07-ca67-4ad1-84a5-7a37b981bc4e","Direct quantification of topological protection in symmetry-protected photonic edge states at telecom wavelengths","Arora, S. (TU Delft QN/Kuipers Lab; Kavli institute of nanoscience Delft); Bauer, T.A. (TU Delft QN/Kuipers Lab; Kavli institute of nanoscience Delft); Barczyk, René (AMOLF); Verhagen, Ewold (AMOLF); Kuipers, L. (TU Delft QN/Quantum Nanoscience; Kavli institute of nanoscience Delft)","","2021","Topological on-chip photonics based on tailored photonic crystals (PhCs) that emulate quantum valley-Hall effects has recently gained widespread interest owing to its promise of robust unidirectional transport of classical and quantum information. We present a direct quantitative evaluation of topological photonic edge eigenstates and their transport properties in the telecom wavelength range using phase-resolved near-field optical microscopy. Experimentally visualizing the detailed sub-wavelength structure of these modes propagating along the interface between two topologically non-trivial mirror-symmetric lattices allows us to map their dispersion relation and differentiate between the contributions of several higher-order Bloch harmonics. Selective probing of forward- and backward-propagating modes as defined by their phase velocities enables direct quantification of topological robustness. Studying near-field propagation in controlled defects allows us to extract upper limits of topological protection in on-chip photonic systems in comparison with conventional PhC waveguides. We find that protected edge states are two orders of magnitude more robust than modes of conventional PhC waveguides. This direct experimental quantification of topological robustness comprises a crucial step toward the application of topologically protected guiding in integrated photonics, allowing for unprecedented error-free photonic quantum networks.","","en","journal article","","","","","","","","","","QN/Quantum Nanoscience","QN/Kuipers Lab","","",""
"uuid:56c42d3c-cc7c-4348-8c94-b526c84377e9","http://resolver.tudelft.nl/uuid:56c42d3c-cc7c-4348-8c94-b526c84377e9","Material intensity database for the Dutch building stock: Towards Big Data in material stock analysis","Sprecher, B. (Universiteit Leiden); Verhagen, T. (Universiteit Leiden); Sauer, Marijn Louise (Gemeente Leiden); Baars, Michel (New Horizon Urban Mining Collective, Raamsdonkveer); Heintz, John L. (TU Delft Design & Construction Management); Fishman, Tomer (Interdisciplinary Center, Herzliya)","","2021","Re-use and recycling in the construction sector is essential to keep resource use in check. Data availability about the material contents of buildings is significant challenge for planning future re-use potentials. Compiling material intensity (MI) data is time and resource intensive. Often studies end up with only a handful of datapoints. In order to adequately cover the diversity of buildings and materials found in cities, and accurately assess material stocks at detailed spatial scopes, many more MI datapoints are needed. In this work, we present a database on the material intensity of the Dutch building stock, containing 61 large-scale demolition projects with a total of 781 datapoints, representing more than 306,000 square meters of built floor space. This dataset is representative of the types of buildings being demolished in the Netherlands. Our data were empirically sourced in collaboration with a demolition company that explicitly focuses on re-using and recycling materials and components. The dataset includes both the structural building materials and component materials, and covers a wide range of building types, sizes, and construction years. Compared to the existing literature, this paper adds significantly more datapoints, and more detail to the different types of materials found in demolition streams. This increase in data volume is a necessary step toward enabling big data methods, such as data mining and machine learning. These methods could be used to uncover previously unrecognized patters in material stocks, or more accurately estimate material stocks in locations that have only sparse data available. This article met the requirements for a Gold-Gold JIE data openness badge described at http://jie.click/badges.","circular economy; construction; industrial ecology; material stocks and flows; urban mining","en","journal article","","","","","","","","","","","Design & Construction Management","","",""
"uuid:fecd16c7-7ad5-4a91-9090-a700a8915438","http://resolver.tudelft.nl/uuid:fecd16c7-7ad5-4a91-9090-a700a8915438","A Two-Dimensional Explanation Framework to Classify AI as Incomprehensible, Interpretable, or Understandable","Verhagen, R.S. (TU Delft Interactive Intelligence); Neerincx, M.A. (TU Delft Interactive Intelligence; TNO); Tielman, M.L. (TU Delft Interactive Intelligence)","Calvaresi, Davide (editor); Najjar, Amro (editor); Winikoff, Michael (editor); Främling, Kary (editor)","2021","Because of recent and rapid developments in Artificial Intelligence (AI), humans and AI-systems increasingly work together in human-agent teams. However, in order to effectively leverage the capabilities of both, AI-systems need to be understandable to their human teammates. The branch of eXplainable AI (XAI) aspires to make AI-systems more understandable to humans, potentially improving human-agent teamwork. Unfortunately, XAI literature suffers from a lack of agreement regarding the definitions of and relations between the four key XAI-concepts: transparency, interpretability, explainability, and understandability. Inspired by both XAI and social sciences literature, we present a two-dimensional framework that defines and relates these concepts in a concise and coherent way, yielding a classification of three types of AI-systems: incomprehensible, interpretable, and understandable. We also discuss how the established relationships can be used to guide future research into XAI, and how the framework could be used during the development of AI-systems as part of human-AI teams.","Explainability; Explainable AI; Human-agent teaming; Interpretability; Transparency; Understandability","en","conference paper","Springer","","","","","Accepted author manuscript","","2022-07-17","","","Interactive Intelligence","","",""
"uuid:83e7bb95-18ef-467f-809c-c449e021b4ba","http://resolver.tudelft.nl/uuid:83e7bb95-18ef-467f-809c-c449e021b4ba","Deducing the physical characteristics of an impactor from the resultant damage on aircraft structures","Massart, Philippe F.R. (Student TU Delft); Dhanisetty, V.S.V. (TU Delft Air Transport & Operations); Kassapoglou, C. (TU Delft Aerospace Structures & Computational Mechanics); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","","2020","This paper proposes an analytical model that uses historical damage dimension data to deduce physical impactor characteristics (size and energy) that has caused a certain resulting damage. Maintenance tasks occur in operations due to impact, however the source of the damage caused in the event remains in most cases unknown. Consequently, by inferring what has caused a certain type of damage from the distribution of the damage type and severity relative to impactor types, maintainers can be better prepared in terms of what to expect from a given impactor source. The developed model introduces a novel transition deformation region between the local deformation and the global plate deflection, allowing for fast and accurate predictions of the impact event. Using the known aluminium structural properties and damage dimensions, the damage data is converted into impactor data. The model is applied in a case study using 120 fuselage dent damages dimensions (length, width, and depth) from a Boeing 777 fleet. The results show that the model deduces impactor characteristics for 94% of the considered damages, ranging up to 240 J and 110 mm for impactor energy and radius respectively.","Aircraft maintenance; Aluminium fuselage; Damage impactors; Damage modelling; Dents; Impact damage; Structural impact","en","journal article","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:c7273233-dbd0-4caf-96de-6135b710592d","http://resolver.tudelft.nl/uuid:c7273233-dbd0-4caf-96de-6135b710592d","Real-Time PPP-RTK Performance Analysis Using Ionospheric Corrections from Multi-Scale Network Configurations","Psychas, D.V. (TU Delft Mathematical Geodesy and Positioning; Fugro Innovation & Technology B.V.); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning)","","2020","The long convergence time required to achieve high-precision position solutions with integer ambiguity resolution-enabled precise point positioning (PPP-RTK) is driven by the presence of ionospheric delays. When precise real-time ionospheric information is available and properly applied, it can strengthen the underlying model and substantially reduce the time required to achieve centimeter-level accuracy. In this study, we present and analyze the real-time PPP-RTK user performance using ionospheric corrections from multi-scale regional networks during a day with medium ionospheric disturbance. It is the goal of this contribution to measure the impact the network dimension has on the ambiguity-resolved user position through the predicted ionospheric corrections. The user-specific undifferenced ionospheric corrections are computed at the network side, along with the satellite phase biases needed for single-receiver ambiguity resolution, using the best linear unbiased predictor. Such corrections necessitate the parameterization of an estimable user receiver code bias, on which emphasis is given in this study. To this end, we process GPS dual-frequency data from four four-station evenly distributed CORS networks in the United States with varying station spacings in order to evaluate if and to what extent the ionospheric corrections from multi-scale networks can improve the user convergence times. Based on a large number of samples, our experimental results showed that sub-10 cm horizontal accuracy can be achieved almost instantaneously in the ionosphere-weighted partially-ambiguity-fixed kinematic PPP-RTK solutions based on corrections from a network with 68 km spacing. Most of the solutions (90%) were shown to require less than 6.0 min, compared to the ionosphere-float PPP solutions that needed 68.5 min. In case of sparser networks with 115, 174 and 237 km spacing, 50% of the horizontal positioning errors are shown to become less than one decimeter after 1.5, 4.0 and 7.0 min, respectively, while 90% of them require 10.5, 16.5 and 20.0 min. We also numerically demonstrated that the user’s convergence times bear a linear relationship with the network density and get shorter as the density increases, for both full and partial ambiguity resolution.","Convergence time; GNSS; Integer ambiguity resolution (IAR); Ionospheric corrections; Network density; PPP-RTK network and user","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:73a39c96-5ebc-474d-bc0d-54d2f4e58e71","http://resolver.tudelft.nl/uuid:73a39c96-5ebc-474d-bc0d-54d2f4e58e71","An Optimal Troposphere Tomography Technique Using the WRF Model Outputs and Topography of the Area","Haji Aghajany, S. (TU Delft Mathematical Geodesy and Positioning; K.N. Toosi University of Technology); Amerian, Yazdan (K.N. Toosi University of Technology); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Rohm, Witold (Wroclaw University of Environmental and Life Sciences); Ma, H. (TU Delft Mathematical Geodesy and Positioning)","","2020","The water vapor content in the atmosphere can be reconstructed using the all-weather condition troposphere tomography technique. In common troposphere tomography, the water vapor of each voxel is represented by an unknown parameter. This means that when the desired spatial resolution is high or study area is large, there will be a huge number of unknown parameters in the problem that need to be solved. This defect can reduce the accuracy of troposphere tomography results. In order to overcome this problem, an optimal voxel-based troposphere tomography using the Weather Research and Forecasting (WRF) model is proposed. The new approach reduces the number of unknown parameters, the number of empty voxels and the role of constraints required to enhance the spatial resolution of tomography results in required areas. Furthermore, the effect of considering the topography of the study area in the tomography model is examined. The obtained water vapor is validated by radiosonde observations and Global Positioning System (GPS) positioning results. Comparison of the results with the radiosonde observations shows that using the WRF model outputs and topography of the area can reduce the Root Mean Square Error (RMSE) by 0.803 gr/m3. Validation using positioning shows that in wet weather conditions, the WRF model outputs and topography reduce the RMSE of the east, north and up components by about 17.42, 10.46 and 20.03 mm, which are equivalent to 46.01%, 35.78% and 53.93%, respectively.","GNSS; Topography; Troposphere tomography; Voxel-based; WRF","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:f78555b0-1d9b-478b-bf0d-f0f4e4241b0d","http://resolver.tudelft.nl/uuid:f78555b0-1d9b-478b-bf0d-f0f4e4241b0d","Conformational flexibility and oligomerization of BRCA2 regions induced by RAD51 interaction","Sidhu, Arshdeep (Erasmus MC); Grosbart, Małgorzata (Erasmus MC); Sanchez González, H. (TU Delft BN/Nynke Dekker Lab; Kavli institute of nanoscience Delft); Verhagen, Bram (Erasmus MC); van der Zon, Nick L.L. (Erasmus MC); Ristić, Dejan (Erasmus MC); van Rossum-Fikkert, Sarah E. (Erasmus MC); Wyman, Claire (Erasmus MC)","","2020","BRCA2 is a key breast cancer associated protein that is predicted to have interspersed regions of intrinsic disorder. Intrinsic disorder coupled with large size likely allows BRCA2 to sample a broad range of conformational space. We expect that the resulting dynamic arrangements of BRCA2 domains are a functionally important aspect of its role in homologous recombination DNA repair. To determine the architectural organization and the associated conformational landscape of BRCA2, we used scanning force microscopy based single molecule analyses to map the flexible regions of the protein and characterize which regions influence oligomerization. We show that the N- and the C-terminal regions are the main flexible regions. Both of these regions also influence BRCA2 oligomerization and interaction with RAD51. In the central Brc repeat region, Brc 1-4 and Brc 5-8 contribute synergistically to BRCA2 interaction with RAD51. We also analysed several single amino acid changes that are potentially clinically relevant and found one, the variant of F1524V, which disrupts key interactions and alters the conformational landscape of the protein. We describe the overall conformation spectrum of BRCA2, which suggests that dynamic structural transitions are key features of its biological function, maintaining genomic stability.","","en","journal article","","","","","","","","","","","BN/Nynke Dekker Lab","","",""
"uuid:91e1b243-a96b-4efd-8bf4-8388d669babf","http://resolver.tudelft.nl/uuid:91e1b243-a96b-4efd-8bf4-8388d669babf","Analysing the Combined Health, Social and Economic Impacts of the Corona Virus Pandemic Using Agent‑Based Social Simulation","Dignum, Frank (Umeå University); Dignum, Virginia (Umeå University); Davidsson, Paul (Malmö University); Ghorbani, Amineh (TU Delft Energie and Industrie); van der Hurk, Mijke (Universiteit Utrecht); Jensen, Maarten (Umeå University); Kammler, Christian (Umeå University); Lorig, Fabian (Malmö University); Ludescher, Luis Gustavo (Umeå University); Melchior, Alexander (Universiteit Utrecht); Mellema, René (Umeå University); Pastrav, Cezara (Umeå University); Vanhee, Loïs (University of Caen); Verhagen, Harko (Stockholm University)","","2020","During the COVID-19 crisis there have been many difficult decisions governments and other decision makers had to make. E.g. do we go for a total lock down or keep schools open? How many people and which people should be tested? Although there are many good models from e.g. epidemiologists on the spread of the virus under certain conditions, these models do not directly translate into the interventions that can be taken by government. Neither can these models contribute to understand the economic and/or social consequences of the interventions. However, effective and sustainable solutions need to take into account this combination of factors. In this paper, we propose an agent-based social simulation tool, ASSOCC, that supports decision makers understand possible consequences of policy interventions, but exploring the combined social, health and economic consequences of these interventions.","","en","journal article","","","","","","","","","","","Energie and Industrie","","",""
"uuid:dbd47266-9a97-4b25-b7fa-67338e2b2424","http://resolver.tudelft.nl/uuid:dbd47266-9a97-4b25-b7fa-67338e2b2424","Direct observation of topological edge states in silicon photonic crystals: Spin, dispersion, and chiral routing","Parappurath, Nikhil (AMOLF); Alpeggiani, F. (TU Delft QN/Kuipers Lab); Kuipers, L. (TU Delft QN/Quantum Nanoscience); Verhagen, Ewold (AMOLF)","","2020","Topological protection in photonics offers new prospects for guiding and manipulating classical and quantum information. The mechanism of spin-orbit coupling promises the emergence of edge states that are helical, exhibiting unidirectional propagation that is topologically protected against back scattering. We directly observe the topological states of a photonic analog of electronic materials exhibiting the quantum spin Hall effect, living at the interface between two silicon photonic crystals with different topological order. Through the far-field radiation that is inherent to the states' existence, we characterize their properties, including linear dispersion and low loss. We find that the edge state pseudospin is encoded in unique circular far-field polarization and linked to unidirectional propagation, thus revealing a signature of the underlying photonic spin-orbit coupling. We use this connection to selectively excite different edge states with polarized light and directly visualize their routing along sharp chiral waveguide junctions.","","en","journal article","","","","","","","","","","QN/Quantum Nanoscience","QN/Kuipers Lab","","",""
"uuid:937423c1-acfc-4f01-b7d8-854787549bd1","http://resolver.tudelft.nl/uuid:937423c1-acfc-4f01-b7d8-854787549bd1","Imaging of inflammatory cellular protagonists in human atherosclerosis: a dual-isotope SPECT approach","Barrett, Hilary E. (Erasmus MC); Meester, Eric J. (Erasmus MC); van Gaalen, Kim (Erasmus MC); van der Heiden, Kim (Erasmus MC); Krenning, Boudewijn J. (Erasmus MC); Beekman, F.J. (TU Delft RST/Biomedical Imaging; MILabs B.V.; University Medical Center Utrecht); Verhagen, H. J. (Erasmus MC); de Jong, M. (Erasmus MC); Gijsen, F.J.H. (Erasmus MC)","","2020","Purpose: Atherosclerotic plaque development and progression signifies a complex inflammatory disease mediated by a multitude of proinflammatory leukocyte subsets. Using single photon emission computed tomography (SPECT) coupled with computed tomography (CT), this study tested a new dual-isotope acquisition protocol to assess each radiotracer’s capability to identify plaque phenotype and inflammation levels pertaining to leukocytes expressing leukocyte function-associated antigen-1 (LFA-1) and the leukocyte subset of proinflammatory macrophages expressing somatostatin receptor subtype-2 (SST2). Individual radiotracer uptake was quantified and the presence of corresponding immunohistological cell markers was assessed. Methods: Human symptomatic carotid plaque segments were obtained from endarterectomy. Segments were incubated in dual-isotope radiotracers [111In]In-DOTA-butylamino-NorBIRT ([111In]In-Danbirt) and [99mTc]Tc-[N0–1 4,Asp0,Tyr3]-octreotate ([99mTc]Tc-Demotate 2) before scanning with SPECT/CT. Plaque phenotype was classified as pathological intimal thickening, fibrous cap atheroma or fibrocalcific using histology sections based on distinct morphological characteristics. Plaque segments were subsequently immuno-stained with LFA-1 and SST2 and quantified in terms of positive area fraction and compared against the corresponding SPECT images. Results: Focal uptake of co-localising dual-radiotracers identified the heterogeneous distribution of inflamed regions in the plaques which co-localised with positive immuno-stained regions of LFA-1 and SST2. [111In]In-Danbirt and [99mTc]Tc-Demotate 2 uptake demonstrated a significant positive correlation (r = 0.651; p = 0.001). Fibrous cap atheroma plaque phenotype correlated with the highest [111In]In-Danbirt and [99mTc]Tc-Demotate 2 uptake compared with fibrocalcific plaques and pathological intimal thickening phenotypes, in line with the immunohistological analyses. Conclusion: A dual-isotope acquisition protocol permits the imaging of multiple leukocyte subsets and the pro-inflammatory macrophages simultaneously in atherosclerotic plaque tissue. [111In]In-Danbirt may have added value for assessing the total inflammation levels in atherosclerotic plaques in addition to classifying plaque phenotype.","Atherosclerosis; Carotid artery; Dual-isotope; Inflammation; Leukocyte; Macrophage; SPECT imaging","en","journal article","","","","","","","","","","","RST/Biomedical Imaging","","",""
"uuid:dd30206a-7ed8-4af3-967f-42c83b49586f","http://resolver.tudelft.nl/uuid:dd30206a-7ed8-4af3-967f-42c83b49586f","A decision support framework and prototype for aircraft dispatch assessment","Koornneef, H. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations; Royal Melbourne Institute of Technology University); Curran, R. (TU Delft Air Transport & Operations)","","2020","When an aircraft experiences an unexpected issue during flight operations, a technician determines whether the aircraft can safely perform the next flight. This operational decision process - known as dispatch assessment - has to happen within limited available time between aircraft arrival and departure. Currently, technicians face two main problems during the assessment: lack of access to decision support information and a time-consuming process for finding relevant information in extensive maintenance manuals. These issues often lead to delays and additional costs and are indicative of three larger challenges in the decision support domain: 1) a paucity of decision support models and applications for operational processes in maintenance; 2) relatively few efforts in applying and evaluating artifacts in experimental and real-life operational settings; and 3) a lack of systematic development, application and evaluation of digitization and automation efforts of complex decision processes in maintenance. This paper applies a design science research approach to address these challenges and introduces two novel artifacts: a decision support framework for real-time decision making in aircraft dispatch, and a web-based prototype tool accessible through mobile solutions. The practical relevance of the framework and prototype is validated through two representative application and evaluation studies, one in an experimental setting and one in an operational environment. Results show significant time savings and strong qualitative indications towards a higher incentive to use documentation and reducing human risk factors that lead to maintenance error.","Aircraft maintenance; Data integration; Decision support; Dispatch assessment; E-maintenance; Information retrieval","en","journal article","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:8ec65979-c6cf-4e78-889c-32e08e8fe5bd","http://resolver.tudelft.nl/uuid:8ec65979-c6cf-4e78-889c-32e08e8fe5bd","B-spline function-based approach for GPS tropospheric tomography","Haji Aghajany, S. (TU Delft Mathematical Geodesy and Positioning; K.N. Toosi University of Technology); Amerian, Yazdan (K.N. Toosi University of Technology); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning)","","2020","Tropospheric tomography is one of the most important techniques to reconstruct three-dimensional (3D) images of the tropospheric water vapor fields using a local GNSS network. In the conventional tropospheric tomography method, called voxel-based tropospheric tomography, the 3D space is divided into many voxels and the amount of water vapor is estimated for each voxel. This method suffers from three disadvantages. First, it needs empirical constraints in order to fix the rank deficiency of the coefficient matrix. Second, the amount of water vapor is assumed to be constant in the 3D space of a voxel despite the large spatial variations of this parameter. Third, the number of unknown parameters is high compared to the number of observations. Therefore, an approach based on mathematical functions, called function-based tropospheric tomography, is presented to overcome these problems. The tropospheric tomography using the voxel-based and function-based approaches is performed using 17 GPS stations. Radiosonde observations and precise point positioning results are used to validate the obtained results. A comparison of the results with the radiosonde data indicates that using the function-based method reduces the mean RMSE by about 0.3 gr/m3. Validation using positioning under different wet conditions shows that in wet weather conditions the difference between the RMSE of the two tropospheric tomography approaches is significant. All the validations show the ability and applicability of the function-based tropospheric tomography approach.","B-spline; Function-based; GPS; Tropospheric tomography; Voxel-based","en","journal article","","","","","","Accepted Author Manuscript","","2021-07-04","","","Mathematical Geodesy and Positioning","","",""
"uuid:7d162d6b-2b0b-438d-8ba4-94d26bff0a44","http://resolver.tudelft.nl/uuid:7d162d6b-2b0b-438d-8ba4-94d26bff0a44","Disposal and recycle economic assessment for aircraft and engine end of life solution evaluation","Zhao, X. (TU Delft Air Transport & Operations; Northwestern Polytechnical University); Verhagen, W.J.C. (TU Delft Air Transport & Operations; Royal Melbourne Institute of Technology University); Curran, R. (TU Delft Air Transport & Operations)","","2020","The present study proposes an economic indicator to support the evaluation of aircraft End of Life (EoL) strategies in view of the increasing demand with regards to aircraft decommissioning. This indicator can be used to evaluate the economic performance and to facilitate the trade-off studies among different strategies. First, Disposal and Recycle (D&R) scenarios related to stakeholders are investigated to identify the core concepts for the economic evaluation. Next, we extracted the aircraft D&R process from various real-life practices. In order to obtain the economic measure for the engineering process, a method of estimating the D&R cost and values are developed by integrating product, process and cost properties. This analysis is demonstrated on an averaged data set and two EoL aircraft cases. In addition, sensitivity analysis is performed to evaluate the impact of the D&R cost, residual value, and salvage value. Results show that the disassembly and dismantling of an aircraft engine possesses relatively more economic gains than that for the aircraft. The main factors influencing the proposed D&R economic indicator are the salvage value and D&R cost for economically efficient D&R cases. In addition, delaying the disposal and recycle process for EoL aircraft can lead to economically unfavorable solutions. The economic indicator combined with the evaluation methods is widely applicable for evaluations of engineering products EoL solutions, and implies a significant contribution of this research to decision making for such complex systems in terms sustainable policy.","Aircraft and aircraft engine Life Cycle Analysis (LCA); Aircraft disposal and recycle process; Disposal and recycle economic indicator; End of Life (EoL); Engineering cost and value analysis","en","journal article","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:a93523e7-70b6-4f99-aad8-1ef6488211af","http://resolver.tudelft.nl/uuid:a93523e7-70b6-4f99-aad8-1ef6488211af","Precise point positioning on the reliable detection of tropospheric model errors","Ma, H. (TU Delft Mathematical Geodesy and Positioning); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning)","","2020","Precise point positioning (PPP) is one of the well-known applications of Global Navigation Satellite System (GNSS) and provides precise positioning solutions using accurate satellite orbit and clock products. The tropospheric delay due to the neutral atmosphere for microwave signals is one of the main sources of measurement error in PPP. As one component of this delay, the hydrostatic delay is usually compensated by using an empirical correction model. However, how to eliminate the effects of the wet delay during a weather event is a challenge because current troposphere models are not capable of considering the complex atmosphere around the receiver during situations such as typhoons, storms, heavy rainfall, et cetera. Thus, how positioning results can be improved if the residual wet delays are taken into account needs to be investigated . In this contribution, a real-time procedure of recursive detection, identification and adaptation (DIA) is applied to detect the model errors which have the same effects on both phase and code observables; e.g., the model error caused by the tropospheric delay. Once the model errors are identified, additional parameters are added to the functional model to account for the measurement residuals. This approach is evaluated with Global Positioning System (GPS) data during two rainfall events in Darwin, Australia, proving the usefulness of compensated residual slant wet delay for positioning results. Comparisons with the standard approach show that the precision of the up component is improved significantly during the periods of the weather events; for the two case studies, 72.46% and 64.41% improvements of root mean squared error (RMS) resulted, and the precision of the horizontal component obtained by the proposed approach is also improved more than 30% compared to the standard approach. The results also show that the identified model errors are concentrated at the beginning of both heavy rainfall processes when the front causes significant spatial and temporal gradients of the integrated water vapor above the receiver.","DIA; GNSS; PPP; Tropospheric delay","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:913e88cc-fb84-4b1f-97cd-3f6191f13f94","http://resolver.tudelft.nl/uuid:913e88cc-fb84-4b1f-97cd-3f6191f13f94","Dynamics in redox metabolism, from stoichiometry towards kinetics","Verhagen, K.J.A. (TU Delft OLD BT/Cell Systems Engineering); van Gulik, W.M. (TU Delft OLD BT/Cell Systems Engineering); Wahl, S.A. (TU Delft OLD BT/Cell Systems Engineering)","","2020","Redox metabolism plays an essential role in the central metabolic network of all living cells, connecting, but at the same time separating, catabolic and anabolic pathways. Redox metabolism is inherently linked to the excretion of overflow metabolites. Overflow metabolism allows for higher substrate uptake rates, potentially outcompeting other microorganisms for the same substrate. Within dynamically changing environments, overflow metabolism can act as storage mechanism, as is shown in many recently described processes. However, for complete understanding of these mechanisms, the intracellular state of the metabolism must be elucidated. In recent years, progress has been made in the field of metabolomics to improve the accuracy and precision of measurements of intracellular and intercompartmental metabolites. This article highlights several of these recent advances, with focus on redox cofactor measurements, both fluorescence and mass spectrometry based.","","en","review","","","","","","","","","","","OLD BT/Cell Systems Engineering","","",""
"uuid:6c814ba9-d67c-448b-9349-b9bb25cbca2a","http://resolver.tudelft.nl/uuid:6c814ba9-d67c-448b-9349-b9bb25cbca2a","Precision analysis of partial ambiguity resolution-enabled PPP using multi-GNSS and multi-frequency signals","Psychas, D.V. (TU Delft Mathematical Geodesy and Positioning; Fugro); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Teunissen, P.J.G. (TU Delft Mathematical Geodesy and Positioning)","","2020","A single-receiver integer ambiguity resolution-enabled precise point positioning (PPP-RTK) user experiences a long convergence time when the rather weak single-constellation dual-frequency ionosphere-float model is used. Nowadays, the rapid development of Global Navigation Satellite Systems (GNSS) provides a multitude of available satellites and frequencies that can serve in improving the user's model strength and, therefore, its ambiguity resolution and positioning capabilities. In this study, we provide insight into and analyze the global impact of a multi-GNSS (GPS, Galileo, BeiDou-3) multi-frequency integration on the expected ambiguity resolution and positioning performance of the ionosphere-float uncombined PPP-RTK user model, and demonstrate whether it is the increased number of satellites or frequencies, or a combination thereof, that speeds up ambiguity-resolved positioning. Moreover, we explore the capabilities of both full (FAR) and partial (PAR) ambiguity resolution, considering the full ambiguity information content with the LAMBDA method, and investigate whether PAR is an efficient solution to the multi-dimensional ambiguity case. The performance of our solutions is assessed in terms of the ambiguity success rate (ASR), the number of epochs (TTFA) to achieve both an ASR criterion and a horizontal positioning precision better than 10 cm, as well as the gain in precision improvement. Based on multi-system multi-frequency simulated data from nine globally distributed stations and a large number of kinematic solutions over a day, we found that the increase in number of frequencies enhances the ambiguity resolution performance, with PAR achieving a TTFA reduction of 70% when five instead of two Galileo frequencies are used, while the ambiguity-float solution is only slightly improved. Further, our numerical results demonstrated that the increase in number of satellites leads to an improvement in both the positioning and ambiguity resolution performance, due to the improved geometry strength. It is shown that the GPS+Galileo+BeiDou solutions can achieve a TTFA of 6.5 and 4.5 min (at 90%) on a global scale when two and three frequencies are used, respectively, without any a priori information on the ionospheric delays. Finally, we analyzed the sensitivity of the PPP-RTK user's performance to changes in the precision of the measurements.","Global navigation satellite systems (GNSS); Integer ambiguity resolution (IAR); Multi-frequency; Multi-GNSS; PPP-RTK; Precision gain numbers","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:db322950-dc17-4291-a6fd-445f95f5b33f","http://resolver.tudelft.nl/uuid:db322950-dc17-4291-a6fd-445f95f5b33f","Assessing the performance of multi-GNSS PPP-RTK in the local area","Ma, H. (TU Delft Mathematical Geodesy and Positioning; Wuhan University); Zhao, Qile (Wuhan University); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Psychas, D.V. (TU Delft Mathematical Geodesy and Positioning; Fugro Innovation & Technology B.V.); Liu, Xianglin (Fugro Innovation & Technology B.V.)","","2020","The benefits of an increased number of global navigation satellite systems (GNSS) in space have been confirmed for the robustness and convergence time of standard precise point positioning (PPP) solutions, as well as improved accuracy when (most of) the ambiguities are fixed. Yet, it is still worthwhile to investigate fast and high-precision GNSS parameter estimation to meet user needs. This contribution focuses on integer ambiguity resolution-enabled Precise Point Positioning (PPP-RTK) in the use of the observations from four global navigation systems, i.e., GPS (Global Positioning System), Galileo (European Global Navigation Satellite System), BDS (Chinese BeiDou Navigation Satellite System), and GLONASS (Global’naya Navigatsionnaya Sputnikova Sistema). An undifferenced and uncombined PPP-RTK model is implemented for which the satellite clock and phase bias corrections are computed from the data processing of a group of stations in a network and then provided to users to help them achieve integer ambiguity resolution on a single receiver by calibrating the satellite phase biases. The dataset is recorded in a local area of the GNSS network of the Netherlands, in which 12 stations are regarded as the reference to generate the corresponding corrections and 21 as the users to assess the performance of the multi-GNSS PPP-RTK in both kinematic and static positioning mode. The results show that the root-mean-square (RMS) errors of the ambiguity float solutions can achieve the same accuracy level of the ambiguity fixed solutions after convergence. The combined GNSS cases, on the contrary, reduce the horizontal RMS of GPS alone with 2 cm level to GPS + Galileo/GPS + Galileo + BDS/GPS + Galileo + BDS + GLONASS with 1 cm level. The convergence time benefits from both multi-GNSS and fixing ambiguities, and the performances of the ambiguity fixed solution are comparable to those of the multi-GNSS ambiguity float solutions. For instance, the convergence time of GPS alone ambiguity fixed solutions to achieve 10 cm three-dimensional (3D) positioning accuracy is 39.5 min, while it is 37 min for GPS + Galileo ambiguity float solutions; moreover, with the same criterion, the convergence time of GE ambiguity fixed solutions is 19 min, which is better than GPS + Galileo + BDS + GLONASS ambiguity float solutions with 28.5 min. The experiments indicate that GPS alone occasionally suffers from a wrong fixing problem; however, this problem does not exist in the combined systems. Finally, integer ambiguity resolution is still necessary for multi-GNSS in the case of fast achieving very-high-accuracy positioning, e.g., sub-centimeter level.","GNSS; Integer ambiguity resolution; PPP; PPP-RTK; Satellite positioning","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:2fcea390-deb2-42ad-9039-291526b86cd1","http://resolver.tudelft.nl/uuid:2fcea390-deb2-42ad-9039-291526b86cd1","Kriging interpolation in modelling tropospheric wet delay","Ma, H. (TU Delft Mathematical Geodesy and Positioning; Wuhan University); Zhao, Qile (Wuhan University); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Psychas, D.V. (TU Delft Mathematical Geodesy and Positioning; Fugro Innovation & Technology B.V.); Dun, H. (TU Delft Mathematical Geodesy and Positioning)","","2020","This contribution implements the Kriging interpolation in predicting the tropospheric wet delays using global navigation satellite system networks. The predicted tropospheric delays can be used in strengthening the precise point positioning models and numerical weather prediction models. In order to evaluate the performances of the Kriging interpolation, a sparse network with 8 stations and a dense network with 19 stations from continuously operating reference stations (CORS) of the Netherlands are selected as the reference. In addition, other 15 CORS stations are selected as users, which are divided into three blocks: 5 stations located approximately in the center of the networks, 5 stations on the edge of the networks and 5 stations outside the networks. The zenith tropospheric wet delays are estimated at the network and user stations through the ionosphere-free positioning model; meanwhile, the predicted wet delays at the user stations are generated by the Kriging interpolation in the use of the tropospheric estimations at the network. The root mean square errors (RMSE) are calculated by comparing the predicted wet delays and estimated wet delays at the same user station. The results show that RMSEs of the stations inside the network are at a sub-centimeter level with an average value of 0.74 cm in the sparse network and 0.69 cm in the dense network. The stations on edge and outside the network can also achieve 1-cm level accuracy, which overcomes the limitation that accurate interpolations can only be attained inside the network. This contribution also presents an insignificant improvement of the prediction accuracy from the sparse network to the dense network over 1-year’s data processing and a seasonal effect on the tropospheric wet delay predictions.","GNSS; Kriging interpolation; Precise point positioning; Troposphere; Tropospheric delay","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:4b766f1f-297c-43d8-877d-4ec371b7ceef","http://resolver.tudelft.nl/uuid:4b766f1f-297c-43d8-877d-4ec371b7ceef","Computational Models That Matter During a Global Pandemic Outbreak: A Call to Action","Squazzoni, Flaminio (University of Milan); Polhillb, J. Gareth (The James Hutton Institute); Edmonds, Bruce (Manchester Metropolitan University); Ahrweiler, Petra (Johannes Gutenberg-University Mainz); Antosz, Patrycja (Rijksuniversiteit Groningen); Scholz, G. (University of Osnabrück); Chappin, E.J.L. (TU Delft Energie and Industrie); Borit, Melania (The Arctic University of Norway); Verhagen, Harko (Stockholm University); Giardini, Francesca (Rijksuniversiteit Groningen); Gilbert, Nigel (University of Surrey)","","2020","The COVID-19 pandemic is causing a dramatic loss of lives worldwide, challenging the sustainability of our health care systems, threatening economic meltdown, and putting pressure on the mental health of individuals (due to social distancing and lock-down measures). The pandemic is also posing severe challenges to the scientific community, with scholars under pressure to respond to policymakers’ demands for advice despite the absence of adequate, trusted data. Understanding the pandemic requires fine-grained data representing specific local conditions and the social reactions of individuals. While experts have built simulation models to estimate disease trajectories that may be enough to guide decision-makers to formulate policy measures to limit the epidemic, they do not cover the full behavioural and social complexity of societies under pandemic crisis. Modelling that has such a large potential impact upon people’s lives is a great responsibility. This paper calls on the scientific community to improve the transparency, access, and rigour of their models. It also calls on stakeholders to improve the rapidity with which data from trusted sources are released to the community (in a fully responsible manner). Responding to the pandemic is a stress test of our collaborative capacity and the social/economic value of research.","Agent-Based Models; COVID-19; Data; Modelling; Pandemic Disease; Policy","en","journal article","","","","","","","","","","","Energie and Industrie","","",""
"uuid:8649311a-05ad-4129-bf53-4f7ab730ac7c","http://resolver.tudelft.nl/uuid:8649311a-05ad-4129-bf53-4f7ab730ac7c","Dynamic aircraft recovery problem - An operational decision support framework","Vink, J. (TU Delft Air Transport & Operations; Ortec B.V.); Santos, Bruno F. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations; Royal Melbourne Institute of Technology University); Medeiros, I. (EMBRAER); Filho, R. (EMBRAER)","","2020","This paper presents a new approach for solving the recovery of the airline schedule when disruptions have occurred. The goal is to develop an operational tool that provides the airline with a solution in less than one minute. The proposed recovery model uses a heuristic that iteratively solves selections of the airline's fleet in order to quickly converge to a good solution. An initial solution is always presented in seconds, after which potential reductions of disruption cost are investigated. The schedule is modeled as a set of parallel time-space networks, using an integer linear programming. The model is solved dynamically; a recovery solution is found whenever a disruption occurs and subsequent disruptions are solved based on the previously found solution. Aircraft maintenance schedules and passenger itineraries are modeled, while crew concerns are indirectly taken into consideration to avoid major disruptions caused by the recovery solution. The approach presented in this paper can be applied on heterogeneous fleets and to both point-to-point and (multi) hub-and-spoke airlines. The performance of the selection heuristic is discussed using a case study on the network of an airline operating in the United States. This case study shows that the selection heuristic can find a globally optimal solution in 90% of the disruption instances tested, within 22 s on average. This corresponds to 4% of the time needed to compute the optimal solution using the entire fleet.","Airline disruption management; Dynamic aircraft recovery; Irregular airline operations","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2021-12-08","","","Air Transport & Operations","","",""
"uuid:b319c249-4a55-4775-8fe3-d259a2c94887","http://resolver.tudelft.nl/uuid:b319c249-4a55-4775-8fe3-d259a2c94887","Comparison of Data-driven Prognostics Models: A Process Perspective","Li, R. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","Beer, Michael (editor); Zio, Enrico (editor)","2019","Remaining useful life (RUL) prediction is crucial for the implementation of Prognostics and Health Management (PHM) systems, enabling application of predictive maintenance strategies for critical systems (e.g. in aviation, power, railway). Existing literature addresses aspects of data-driven prognostic approaches, with a predominant focus on introducing and testing various novel prediction techniques which are purposed towards improving prediction accuracy performance. However, a relative lack of research can be identified when considering a comparative evaluation of competing for data-driven approaches. In particular, the contributing process elements and characteristics of data-driven prognostics methods are typically not compared in detail. To overcome these drawbacks, this paper aims to evaluate the underlying technical processes for statistical and artificial neural networks (ANN) methods for prognostics. A case study is conducted to implement both approaches on the PHM08 Challenge Data Set for comparison. This research comprehensively compares the statistical and ANN prognostic methods in a systematic manner, covering and comparing their respective technical processes, and evaluates the results with respect to prediction accuracy","Remaining useful life (RUL); Prognostics and Health Management (PHM); Data-Driven Prognostics; Statistical Prognostic; Artificial Neural Network (ANN)","en","conference paper","Research Publishing","","","","","","","","","","Air Transport & Operations","","",""
"uuid:2f2802ad-6071-414b-bb49-bdc5cc171f53","http://resolver.tudelft.nl/uuid:2f2802ad-6071-414b-bb49-bdc5cc171f53","Preliminary analysis of the ionosphere-corrected PPP-RTK user performance.","Psychas, D.V. (TU Delft Mathematical Geodesy and Positioning; Fugro); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Liu, Xianglin (Fugro Intersite B.V.)","","2019","","","en","abstract","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:ea589e0b-077a-458f-9097-468e5f13d1e9","http://resolver.tudelft.nl/uuid:ea589e0b-077a-458f-9097-468e5f13d1e9","Preliminary analysis of ionosphere-corrected PPP-RTK user performance","Psychas, D.V. (TU Delft Mathematical Geodesy and Positioning; Fugro); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Liu, Xianglin (Fugro Intersite B.V.)","","2019","","","en","poster","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:df861a98-49a6-456f-83d9-21dc970aae03","http://resolver.tudelft.nl/uuid:df861a98-49a6-456f-83d9-21dc970aae03","Assessment of ionospheric corrections for PPP-RTK using regional ionosphere modelling","Psychas, D.V. (TU Delft Mathematical Geodesy and Positioning; Fugro); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Liu, X. (Fugro); Memarzadeh, Y. (Fugro); Visser, H. (Fugro)","","2019","This paper presents an analysis of the ionospheric corrections required to get a significant improvement in PPP-RTK performance. The main aim was to determine the improvement in the position precision and Time-To-First-Fix in the PPP-RTK user side using ionospheric corrections computed from a network. The study consists of two main steps. The first one includes an empirical investigation of the ionosphere model precision necessary to greatly improve the PPP-RTK performance in a simulated environment in terms of precision and convergence time. In the second one, an optimal ionosphere representation was developed to provide precise ionospheric corrections by parameterizing the ionospheric slant delays after the PPP-RTK network processing in terms of ionosphere model coefficients and differential code biases using real GNSS measurements. Experimental results demonstrate that the proposed methodology can be used for reliable regional ionosphere modeling and satellite code bias estimation, due to the consistency of the satellite code bias estimates with those provided from the International GNSS Service Analysis Centres, the high stability of the estimated receiver and satellite code biases and the low least-squares residuals of the network-based ionosphere modeling solution. Finally, it has been shown that the precision of ionospheric corrections at zenith needs to be better than 5 cm to enable faster PPP-RTK solutions.","integer ambiguity resolution; ionospheric corrections; PPP-RTK; regional ionosphere modeling; success rate; time-to-frst-fx","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:df203dde-6cca-4375-85d2-8b2dbce613cb","http://resolver.tudelft.nl/uuid:df203dde-6cca-4375-85d2-8b2dbce613cb","Introduction to bed, bank and shore protection: Revised edition","Schiereck, G.J. (TU Delft Coastal Engineering); Verhagen, H.J. (TU Delft Coastal Engineering)","","2019","","Shore protection","en","book","Delft Academic Press","978-90-6562-4413","","","","","","","","","Coastal Engineering","","",""
"uuid:2ba23185-5a96-408a-914f-a71f7751053f","http://resolver.tudelft.nl/uuid:2ba23185-5a96-408a-914f-a71f7751053f","Identifying strategic maintenance capacity for accidental damage occurrence in aircraft operations","Narayanan, Prasobh (Student TU Delft); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Dhanisetty, V.S.V. (TU Delft Air Transport & Operations)","","2019","Airline operators face accidental damages on their fleet of aircraft as part of operational practice. Individual occurrences are hard to predict; consequently, the approach towards repairing accidental damage is reactive in aircraft maintenance practice. However, by aggregating occurrence data and predicting future occurrence rates, it is possible to predict future long-term (strategic) demand for maintenance capacity. In this paper, a novel approach for integration of reliability modelling and inventory control is presented. Here, the concept of a base stock policy has been translated to the maintenance slot capacity problem to determine long-term cost-optimal capacity. Demand has been modelled using a superposed Non-homogeneous Poisson Process (NHPP). A case study has been performed on damage data from a fleet of Boeing 777 aircraft. The results prove the feasibility of adopting an integrated approach towards strategic capacity identification, using real-life data to predict future damage occurrence and associated maintenance slot requirements.","aircraft maintenance; inventory control; stochastic process; strategic capacity identification","en","journal article","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:ee57953c-9bc5-4d7e-a66c-acae292ba4df","http://resolver.tudelft.nl/uuid:ee57953c-9bc5-4d7e-a66c-acae292ba4df","Financial benefits of mangroves for surge prone high-value areas","Verhagen, H.J. (TU Delft Coastal Engineering)","","2019","In this paper, protection options for a high-value, industrial area along the coast of West Bengal (India) are investigated. The options are designed to protect against cyclone surges with a probability of 1/100 per year. Two alternatives are compared, a classical solution of a dike with a revetment and a solution with a mangrove belt in front of the dike. The results reveal that from a pure infrastructural cash-flow point-of-view, the mangrove solution is at least 25% cheaper than the classical solution with a rock revetment. An important finding is that this conclusion does not need the financial evaluation of the obvious additional ecological advantages that mangroves offer. It is postulated that these results are generally valid for high-value coastal areas under the attack of waves during storm surges.","Cyclone surge; Dike; Levee; Mangrove; Overtopping; Sea defence structure; Storm surge","en","journal article","","","","","","","","","","","Coastal Engineering","","",""
"uuid:33418c1a-66da-47ed-b039-e99102c9885e","http://resolver.tudelft.nl/uuid:33418c1a-66da-47ed-b039-e99102c9885e","Genetic factors associated with a poor outcome in head and neck cancer patients receiving definitive chemoradiotherapy","Vossen, David M. (Netherlands Cancer Institute); Verhagen, Caroline V.M. (Netherlands Cancer Institute); van der Heijden, Martijn (Netherlands Cancer Institute); Essers, Paul B.M. (Netherlands Cancer Institute); Bartelink, Harry (Netherlands Cancer Institute); Verheij, Marcel (Netherlands Cancer Institute); Wessels, L.F.A. (TU Delft Pattern Recognition and Bioinformatics; Netherlands Cancer Institute); van den Brekel, Michiel W.M. (Netherlands Cancer Institute; Universiteit van Amsterdam; Amsterdam UMC); Vens, Conchita (Netherlands Cancer Institute)","","2019","About half of advanced stage head and neck squamous cell carcinoma (HNSCC) patients can be cured by chemoradiotherapy. Patient outcome may be partially determined by the genetic alterations in HNSCC, rendering these alterations promising candidate prognostic factors and/or therapeutic targets. However, their relevance in patient outcome prognosis remains to be assessed in patients that receive standard-of-care chemoradiotherapy. We therefore tested whether frequent genetic alterations were associated with progression free survival (PFS) in advanced stage HNSCC patients who were uniformly treated with definitive platinum-based chemoradiotherapy. To this end, we performed targeted DNA sequencing on frozen pre-treatment tumor biopsy material from 77 patients with advanced stage oro- and hypopharyngeal carcinoma. This provided somatic point mutation and copy number aberration data of 556 genes. The most frequently mutated genes, TP53 (62%), CCND1 (51%), CDKN2A (30%) and PIK3CA (21%), were not associated with PFS. However, co-occurring CCND1 and CDKN2A mutations were associated with short PFS (HR 2.24, p = 0.028) in HPV-negative tumors. Furthermore, tumor mutational burden (sum of somatic point mutations) showed a trend towards decreased PFS (HR 1.9, p = 0.089), and chromosomal instability (CIN) was associated with shorter PFS (HR 2.3, p = 0.023), independent of HPV status. Our results show that tumor mutational burden, CIN markers, and co-occurring CCND1 and CDKN2A mutations are associated with chemoradiotherapy outcomes in advanced stage oro- and hypopharyngeal HNSCC patients, thereby highlighting their prognostic potential. Given their poor prognosis association and link to biological targets, they may also identify patients for novel targeted therapies and immunotherapies","Chemoradiotherapy; DNA sequence analysis; Genomics; Head and neck squamous cell carcinoma; Mutation; Pharyngeal neoplasms; Prognosis","en","journal article","","","","","","","","","","","Pattern Recognition and Bioinformatics","","",""
"uuid:a4f85078-1586-4006-8ea3-b6b84d4df783","http://resolver.tudelft.nl/uuid:a4f85078-1586-4006-8ea3-b6b84d4df783","Retirement optimization through aircraft transfers and employment","Newcamp, Jeffrey (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Santos, Bruno F. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","","2019","Military aircraft retirements are an afterthought for many lifecycle planners. More active management of end-of-life fleets can yield increased confidence in fleet capability and retirement timelines. This work provides fleet managers with a tool to manage remaining aircraft flight hours to yield a desired fleet retirement pattern. It solves an equivalent flight hour minimization problem using a mixed-integer linear programming model for a military aircraft fleet having a network with basing and mission type constraints. The model minimizes differences in remaining equivalent flight hours for individual aircraft in future years, thereby allowing a fleet manager to alter the timeline for retirement of individual aircraft. A relocation cost is applied to discourage excessive, costly aircraft relocations. The United States Air Force A-10 Thunderbolt II aircraft is used as a case study while disruptions such as deployments are modeled to show the methodology's robustness. This work proves that a fleet of aircraft with dissimilar utilization histories and varying amounts of remaining useful lifetime can be actively managed to change the time at which individual aircraft are ready for retirement. The benefit to fleet managers is the ability to extract additional lifetime out of their aircraft prior to retirement.","Aircraft retirement; Aircraft transfers; Military aircraft; Mixed-integer linear programming","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2021-12-08","","","Air Transport & Operations","","",""
"uuid:a945eca8-0c0f-4f7c-8e11-2e525d2f77fd","http://resolver.tudelft.nl/uuid:a945eca8-0c0f-4f7c-8e11-2e525d2f77fd","A Mobile decision support system for aircraft dispatch","Koornneef, H. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","","2019","Delays are costly to airlines in both money and image. A significant number of delays is caused by unexpected technical failures of aircraft systems or components. These failures, if not dealt with efficiently, can cause disruptions in the flight schedule and network. The annual costs of these type of disruptions add up to an estimated cost of € 2.8 billion in Europe alone. Determining the optimal course of action when an unexpected failure occurs is currently troublesome, leading to inefficient dispatch decision making.","Aircraft maintenance; Decision Support System; Dispatch decision","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","","","","","","Air Transport & Operations","","",""
"uuid:f038eaaa-71c2-4816-9c78-fc2c03ba2110","http://resolver.tudelft.nl/uuid:f038eaaa-71c2-4816-9c78-fc2c03ba2110","Transdisciplinary systems engineering: Implications, challenges and research agenda","Wognum, Nel (TU Delft Air Transport & Operations); Bil, Cees (Royal Melbourne Institute of Technology University); Elgh, Fredrik (Jönköping University); Peruzzini, Margherita (Università Degli Studi di Modena e Reggio Emilia); Stjepandić, Josip (PROSTEP AG); Verhagen, W.J.C. (TU Delft Air Transport & Operations)","","2019","Transdisciplinary processes have been the subject of research since several decades already. Transdisciplinary processes are aimed at solving ill-defined and socially relevant problems. Many researchers have studied transdisciplinary processes and have tried to understand the essentials of transdisciplinarity. Many engineering problems can be characterised as ill-defined and socially relevant, too. Although transdisciplinary engineering cannot widely be found in the literature yet, a transdisciplinary approach is deemed relevant for many engineering problems. With this paper we aim to present an overview of the literature on research into transdisciplinary processes and investigate the relevance of a transdisciplinary approach in engineering domains. After a brief description of past research on transdisciplinarity, implications for engineering research, engineering practice, and engineering education are identified. In all three areas, the current situation is described, while challenges are identified that still exist. The paper ends with a research agenda for transdisciplinary engineering.","Engineering education; Industry 4.0; Project-based learning; Social relevance; Transdisciplinary collaboration; Transdisciplinary engineering; Transdisciplinary processes; Transdisciplinary research; Transdisciplinary systems","en","journal article","","","","","","","","2020-04-01","","","Air Transport & Operations","","",""
"uuid:e199eedf-0318-4a8b-9371-da75c9b48ebd","http://resolver.tudelft.nl/uuid:e199eedf-0318-4a8b-9371-da75c9b48ebd","Assessment of ionospheric corrections for PPP-RTK using S-system theory","Psychas, D.V. (TU Delft Mathematical Geodesy and Positioning); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Liu, X. (Fugro)","","2018","","","en","other","","","","","","Power Point Presentatie","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:ed40c858-96a9-4791-b9d1-8dd657ee7ae8","http://resolver.tudelft.nl/uuid:ed40c858-96a9-4791-b9d1-8dd657ee7ae8","Adaptive, variable resolution grids for bathymetric applications using a quadtree approach","Toodesh, R. (TU Delft Mathematical Geodesy and Positioning); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning)","","2018","The spatial sampling often used to process and represent bathymetric data are of fixed grid resolution where the least depth value is stored in each grid cell. This results in Digital Elevation Models (DEMs) that are used to depict the underlying features of the seafloor. With the discretion of the user, the resulting DEMs used may either be of coarse resolution or a very fine resolution surface which provides as many details as possible. However, depending on the resolution of the data collected and the variability of the seafloor, the arbitrary user defined grid resolution is not the best option. Hence we address the problem of finding an optimal grid resolution for representing and processing the bathymetric data for the application of bathymetric risk assessment whilst maintaining computational efficiency. Here we adopt the quadtree decomposition approach. In addition, the research suggests the optimal criteria and standard deviation threshold, σ t h {\sigma -{th}} values for this particular application. These suggestions are still flexible and can be optimized for this application depending on the end user requirements. Previous studies have focused only on the splitting criteria or the constrained criteria to ensure that there is homogeneous accuracy over the entire dataset. However, an investigation into the threshold selection for the standard deviation, σ t h {\sigma -{th}} which describes the variability in the dataset is one of the most important splitting criterion, that is still lacking. Also, a new approach to store the depths in the grid in a time ordered approach for each epoch is shown. By optimizing the criteria for the quadtree decomposition and time series algorithm, the approaches shown in this paper provide the adaptive, accurate DEM which makes optimal use of the available bathymetric data for the Netherlands Continental Shelf (NCS) as the study area. This data preparation step forms the basis for developing a probabilistic approach to assigning hydrographic resurvey frequencies in the NCS.","Bathymetry; Digital Elevation Model; Quadtree; Time Series; Variable Resolution Grid","en","journal article","","","","","","","","2019-06-01","","","Mathematical Geodesy and Positioning","","",""
"uuid:24476b44-b06f-400b-ad30-d10cb0598d16","http://resolver.tudelft.nl/uuid:24476b44-b06f-400b-ad30-d10cb0598d16","Assessment of ionospheric corrections for PPP-RTK using regional ionosphere modeling (PPT)","Psychas, D.V. (TU Delft Mathematical Geodesy and Positioning; Fugro); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Liu, X. (Fugro); Memarzadeh, Y. (Fugro); Visser, H. (Fugro); Teunissen, P.J.G. (TU Delft Mathematical Geodesy and Positioning; Curtin University of Technology)","","2018","","","en","other","","","","","","Power Point Presentatie","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:32c3ddff-fe90-4351-aef6-f0866dc361b6","http://resolver.tudelft.nl/uuid:32c3ddff-fe90-4351-aef6-f0866dc361b6","Assessment of ionospheric corrections for PPP-RTK using regional ionosphere modelling","Psychas, D.V. (TU Delft Mathematical Geodesy and Positioning; Fugro); Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Liu, X. (Fugro); Memarzadeh, Y. (Fugro); Visser, H. (Fugro); Teunissen, P.J.G. (TU Delft Mathematical Geodesy and Positioning; Curtin University of Technology)","","2018","","","en","abstract","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:2d9a3bdd-0640-4538-a6cb-ae449b291891","http://resolver.tudelft.nl/uuid:2d9a3bdd-0640-4538-a6cb-ae449b291891","Predictive maintenance for aircraft components using proportional hazard models","Verhagen, W.J.C. (TU Delft Air Transport & Operations); De Boer, Lennaert W.M. (Student TU Delft)","","2018","Unscheduled maintenance can contribute significantly to an airline's cost outlay. Reliability analysis can help to identify and plan for maintenance events. Reliability analysis in industry is often limited to statistically based approaches that incorporate failure times as the primary stochastic variable, with additional strict assumptions regarding independence of events and underlying distributions of failure phenomena. This foregoes the complex nature of aircraft operations, where a whole range of operational factors may influence the probability of occurrence of a maintenance event. The aim of this research is to identify operational factors affecting component reliability and to assess whether these can be used to reduce the number of unscheduled occurrences (i.e. failures). To do so, a data-driven approach is adopted where historical operational and maintenance data is gathered and analysed to identify operational factors with a measurable influence on maintenance event occurrence. Both time-independent and time-dependent Proportional Hazard Models (PHMs), models which incorporate operational factors as covariates, are employed to generate reliability estimates. Results obtained from analysing historical data of a set of nine components with respect to unscheduled removals indicates that adopting new maintenance schedules, derived from the proposed reliability models, can reduce the number of unscheduled occurrences.","Predictive maintenance; Proportional hazard model; Unscheduled maintenance","en","journal article","","","","","","","","2020-05-31","","","Air Transport & Operations","","",""
"uuid:1f1404e3-09e2-4b6c-9996-46f9bae3c0e5","http://resolver.tudelft.nl/uuid:1f1404e3-09e2-4b6c-9996-46f9bae3c0e5","A decentralized approach to formation flight routing of long-haul commercial flights","Verhagen, Collin M.A. (Student TU Delft); Visser, H.G. (TU Delft Air Transport & Operations); Santos, Bruno F. (TU Delft Air Transport & Operations)","","2018","This paper describes the development of an optimization-based cooperative planning system for the efficient routing and scheduling of extended flight formations. This study considers the use of formation flight as a means to reduce the overall fuel consumption in long-haul airline operations. It elaborates on the operational implementation of formation flight, particularly focusing on the formation flight routing. A completely decentralized approach is presented, in the sense that formation flight is not planned pre-flight and is not subjected to any predefined routing restrictions. A greedy communication scheme is defined through which all participating aircraft are allowed to communicate with neighboring aircraft in order to establish flight formations in flight. A constraint on the formation-flight-induced additional flight time is introduced in order to suppress the occurrence of large detours in the assembly of flight formations. A transatlantic case study is presented that considers 347 eastbound flights. Assuming a 10% fuel flow reduction for any trailing aircraft in a formation, the overall network-wide fuel savings were estimated at 4.3% at the expense of an additional flight time of 10.3 min per flight on average. In this transatlantic long-haul scenario, a formation flight usage rate of 73% was realized.","decentralized planning; Flight formation; flight routing; fuel efficiency","en","journal article","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:629f338e-fef7-41d8-8f10-c367edde6f9d","http://resolver.tudelft.nl/uuid:629f338e-fef7-41d8-8f10-c367edde6f9d","Transdisciplinary Engineering Research Challenges","Wognum, Nel (TU Delft Air Transport & Operations); Bil, Cees (Royal Melbourne Institute of Technology University); Elghc, Fredrik (Università di Modena e Reggio Emilia); Peruzzini, Margherita (Università di Modena e Reggio Emilia); Stjepandic, Josip (PROSTEP AG); Verhagen, W.J.C. (TU Delft Air Transport & Operations)","Peruzzini, Margherita (editor); Pellicciari, Marcello (editor); Bil, Cees (editor); Stjepandić, Josip (editor); Wognum, Nel (editor)","2018","Transdisciplinary research (TDR) has been the subject of discourse in the past few decades, but has bot been studied much in the context of engineering problems. Many engineering problems can be characterized as ill-defined, like open innovation, adoption of new technology, business development, and the adoption of the Industry 4.0 concept. Transdisciplinary engineering research (TDER) is also performed in large projects by multi-disciplinary teams, as in TDR projects, including stakeholders and people from practice. Such projects may last long, often years. In such large projects, the involved disciplines should include both engineering disciplines as well as disciplines from social sciences. In this paper we address the challenges that exist in adopting a TDER approach. Universities need to prepare students to work in TDER projects. We discuss the current situation in transdisciplinary engineering education (TDEE) and identify challenges that need to be addressed for including TDEE in curricula. The paper ends with a summary and ideas for further research.","","en","conference paper","IOS Press","","","","","","","","","","Air Transport & Operations","","",""
"uuid:1ebe4d1a-bc53-47de-bf55-281feeef6bf5","http://resolver.tudelft.nl/uuid:1ebe4d1a-bc53-47de-bf55-281feeef6bf5","Identification of Strategic Maintenance","Narayanan, Prasobh (Student TU Delft); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Dhanisetty, V.S.V. (TU Delft Air Transport & Operations)","Peruzzini, Margherita (editor); Pellicciari, Marcello (editor); Bil, Cees (editor); Stjepandić, Josip (editor); Wognum, Nel (editor)","2018","Airline Maintenance and Engineering (M&E) organizations face accidental damages on their fleet of aircraft as part of daily practice. As this type of damage is stochastic in nature, the approach towards repairing accidental damage is reactive in practice. However, it is possible to predict future long-term (strategic) demand for maintenance resources associated with accidental damages and use this to identify required capacity. To achieve the mutually related goals of prediction of future repairs and determination of capacity, a novel approach for integration of reliability modelling and inventory control is presented in this paper. Here, the concept of inventory control has been specifically applied to determine the maintenance capacity by taking into account the stochastic demand related to unscheduled repairs following from accidental damages. To predict demand, a Non-homogeneous Poisson Process (NHPP) reliability model has been adopted. The reliability model includes superpositioning, through which failure behaviour at aircraft fleet-level can be estimated and subsequently simulated. The resulting demand is fed into a single-system, single location base-stock inventory model. This allows for determination of strategic capacity based on optimum costs as well as service level requirements. A case study has been performed on a fleet of Boeing 777 aircraft of a major European airline. The results prove the feasibility of adopting an integrated approach towards strategic capacity identification, using real-life data to predict future demand occurrence.","Aircraft maintenance; strategic resource scheduling; reliability","en","conference paper","IOS Press","","","","","","","","","","Air Transport & Operations","","",""
"uuid:32115b67-008b-4111-876d-66be3c8324ca","http://resolver.tudelft.nl/uuid:32115b67-008b-4111-876d-66be3c8324ca","A Functional Architecture of Prognostics and Health Management using a Systems Engineering Approach","Li, R. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","","2018","Prognostic and Health Management (PHM) describes a set of capabilities that enable effective and efficient approaches towards data analysis for fault diagnostics and failure prognostics. This can support decision making related to health management, sustainment and operation of critical systems, such as aviation systems. As a result of the rapidly growing interest in PHM, a substantial amount of research proposes and discusses PHM frameworks and system architectures. Previous research efforts conceptual formulation of design methodology to proposes a set of PHM system architectures based on different frameworks, and the derivation of architectures from system requirements. However, further interpretations of PHM system architecture derived from requirements in functional view are lacking. Research on a generic PHM architecture allowing communication and integration with the various contributing systems are lacking. To address these gaps, this research outlines an architecture design methodology incorporating a functional view from a systems engineering perspective. In addition, it proposes a functional architecture for PHM system as the application of the methodology, which has compatibility and interoperability to integrate with the various systems, due to its compliance with the standard of Open System Architecture for Condition-Based Maintenance (OSA-CBM).","","en","conference paper","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:c3b278e2-7255-4d45-84e9-d2702587f348","http://resolver.tudelft.nl/uuid:c3b278e2-7255-4d45-84e9-d2702587f348","Role of variant allele fraction and rare SNP filtering to improve cellular DNA repair endpoint association","Vossen, David M. (Netherlands Cancer Institute); Verhagen, Caroline V.M. (Netherlands Cancer Institute); Grénman, Reidar (University of Turku); Kluin, Roelof J.C. (Netherlands Cancer Institute); Verheij, Marcel (Netherlands Cancer Institute); Van Den Brekel, Michiel W.M. (Universiteit van Amsterdam; Amsterdam UMC); Wessels, L.F.A. (TU Delft Pattern Recognition and Bioinformatics; Netherlands Cancer Institute); Vens, Conchita (Netherlands Cancer Institute)","","2018","Background Large cancer genome studies continue to reveal new players in treatment response and tumorigenesis. The discrimination of functional alterations from the abundance of passenger genetic alterations still poses challenges and determines DNA sequence variant selection procedures. Here we evaluate variant selection strategies that select homozygous variants and rare SNPs and assess its value in detecting tumor cells with DNA repair defects. Methods To this end we employed a panel of 29 patient-derived head and neck squamous cell carcinoma (HNSCC) cell lines, of which a subset harbors DNA repair defects. Mitomycin C (MMC) sensitivity was used as functional endpoint of DNA crosslink repair deficiency. 556 genes including the Fanconi anemia (FA) and homologous recombination (HR) genes, whose products strongly determine MMC response, were capture-sequenced. Results We show a strong association between MMC sensitivity, thus loss of DNA repair function, and the presence of homozygous and rare SNPs in the relevant FA/HR genes. Excluding such selection criteria impedes the discrimination of crosslink repair status by mutation analysis. Applied to all KEGG pathways, we find that the association with MMC sensitivity is strongest in the KEGG FA pathway, therefore also demonstrating the value of such selection strategies for exploratory analyses. Variant analyses in 56 clinical samples demonstrate that homozygous variants occur more frequently in tumor suppressor genes than oncogenes further supporting the role of a homozygosity criterion to improve gene function association or tumor suppressor gene identification studies. Conclusion Together our data show that the detection of relevant genes or of repair pathway defected tumor cells can be improved by the consideration of allele zygosity and SNP allele frequencies.","","en","journal article","","","","","","","","","","","Pattern Recognition and Bioinformatics","","",""
"uuid:4a3b6876-1205-4a7b-ade6-c5474d6868c8","http://resolver.tudelft.nl/uuid:4a3b6876-1205-4a7b-ade6-c5474d6868c8","Integrating Maintenance Work Progress Monitoring into Aircraft Maintenance Planning Decision Support","Callewaert, Pieter; Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","Gherman, B. (editor); Porumbel, L. (editor)","2018","A decision support framework is proposed, allowing for the integration of aircraft maintenance work progress monitoring into the aircraft maintenance planning decision support process. The framework is able to monitor the progression of planned maintenance by analysing real-time data on work progress. This can be used to explore optimal task planning in case of delays or maintenance being ahead of schedule. Using a combination of reliability analysis, cost analysis, decision alternative generation and ranking yields a decision support tool which is able to deal with the stochastic nature of maintenance task execution. Case study results indicate that the framework is able to generate decision alternatives with a lower total cost than the reference alternative, while at the same time optimising the maintenance planning, resulting in a possible reduction of the maintenance costs of 45 to 90% (depending on parameter settings).","Maintenance planning; work progress monitoring; decision framework","en","conference paper","Elsevier","","","","","","","","","","Air Transport & Operations","","",""
"uuid:4e630262-b3cc-49e5-8434-cfe7ffdcf524","http://resolver.tudelft.nl/uuid:4e630262-b3cc-49e5-8434-cfe7ffdcf524","Identification of Optimal Preventive Maintenance Decisions for Composite Components","Laks, P.; Verhagen, W.J.C. (TU Delft Air Transport & Operations)","Gherman, B. (editor); Porumbel, I. (editor)","2018","This research proposes a decision support tool which identifies cost-optimal maintenance decisions for a given planning period. Simultaneously, the reliability state of the component is kept at or below a given reliability threshold: a failure limit policy applies. The tool is developed to support repair-or-replacement decision making for composite components likely to suffer impact damage. As a core part of the tool, a cost minimization problem is defined and solved using a search tree algorithm with heuristic constraints. Application to a case study which utilizes historical damage data and subsequent simulation shows the potential of the tool to identify cost-minimal maintenance decisions. The decision support tool is capable of incorporating a wide range of parameters to study preventive maintenance decision making in depth","","en","conference paper","Elsevier","","","","","","","","","","Air Transport & Operations","","",""
"uuid:5757f8cb-e964-4b40-839e-b812d2b5f246","http://resolver.tudelft.nl/uuid:5757f8cb-e964-4b40-839e-b812d2b5f246","Insulator-to-Metal Transition at Oxide Interfaces Induced by WO3 Overlayers","Mattoni, G. (TU Delft QN/Caviglia Lab; Kavli institute of nanoscience Delft); Baek, David J. (Cornell University); Manca, N. (TU Delft QN/Caviglia Lab; Kavli institute of nanoscience Delft); Verhagen, N.F. (Kavli institute of nanoscience Delft; Student TU Delft); Groenendijk, D.J. (TU Delft QN/Caviglia Lab; Kavli institute of nanoscience Delft); Kourkoutis, Lena F. (Cornell University); Filippetti, Alessio (University of Cagliari; CNR-IOM); Caviglia, A. (TU Delft QN/Caviglia Lab)","","2017","Interfaces between complex oxides constitute a unique playground for two-dimensional electron systems (2DESs), where superconductivity and magnetism can arise from combinations of bulk insulators. The 2DES at the LaAlO3/SrTiO3 interface is one of the most studied in this regard, and its origin is determined by the polar field in LaAlO3 as well as by the presence of point defects, like oxygen vacancies and intermixed cations. These defects usually reside in the conduction channel and are responsible for a decrease of the electronic mobility. In this work, we use an amorphous WO3 overlayer to obtain a high-mobility 2DES in WO3/LaAlO3/SrTiO3 heterostructures. The studied system shows a sharp insulator-to-metal transition as a function of both LaAlO3 and WO3 layer thickness. Low-temperature magnetotransport reveals a strong magnetoresistance reaching 900% at 10 T and 1.5 K, the presence of multiple conduction channels with carrier mobility up to 80 000 cm2 V-1 s-1, and quantum oscillations of conductance.","high mobility; LaAlO/SrTiO interface; metal-insulator; quantum oscillations; strong classical magnetoresistance; two-dimensional electron systems; WO overlayers","en","journal article","","","","","","","","2018-11-07","","","QN/Caviglia Lab","","",""
"uuid:a5190c45-516a-472e-9580-9c088df5dc86","http://resolver.tudelft.nl/uuid:a5190c45-516a-472e-9580-9c088df5dc86","First Tests on the Symmetrical Breakwater Armor Unit Crablock","Salauddin, M (Chittagong University of Engineering and Technology; IHE Delft Institute for Water Education); Broere, A.; van der Meer, J.W. (IHE Delft Institute for Water Education); Verhagen, H.J. (TU Delft Coastal Engineering); Bijl, E (CDR International)","","2017","Single layer concrete armor systems are being widely used nowadays in the design of rubble mound breakwaters. Recently, a new concrete armor unit has been developed and applied as single layer armor system in the repair works of one damaged breakwater at Al Fujeirah, UAE. It has a symmetrical shape, in contrast to most other units. Modern single layer concrete armor units that exist at this moment have design guidelines in terms of placement, stability and overtopping. However, because of lack of laboratory research and the little experience of using Crablock, no design guidance exists yet for this new single layer block compared to other existing one layer units. Being a new armor unit, the placement was investigated first. Then physical model tests were performed in a wave flume to come up with results on stability and wave overtopping. Furthermore, to determine the interlocking properties of armor units, pull tests were also conducted in this research. The placement tests showed that uniform placement was best achieved with a rectangular grid on a relatively small underlayer of rock. Test results on stability showed that longer waves affected the armor layer a little more, with more rocking and earlier start of damage. Packing density as well as placement pattern showed no influence on wave overtopping. The overtopping tests gave larger overtopping than expected, which might be due to the fairly steep 1:30 foreshore that gave a large ratio of significant wave-height from the time domain and the spectral wave-height.","Crablock; placement pattern; single layer armor; stability; wave overtopping","en","journal article","","","","","","","","2019-02-01","","","Coastal Engineering","","",""
"uuid:79de129d-415e-4662-bdc5-3d02ce4a8b5f","http://resolver.tudelft.nl/uuid:79de129d-415e-4662-bdc5-3d02ce4a8b5f","Reconstructing the scattering matrix of photonic systems from quasinormal modes","Alpeggiani, F. (TU Delft QN/Kuipers Lab; Kavli institute of nanoscience Delft); Parappurath, N. (Center for Nanophotonics); Verhagen, Ewold (Center for Nanophotonics); Kuipers, L. (TU Delft QN/Quantum Nanoscience; Kavli institute of nanoscience Delft)","","2017","The scattering matrix is a fundamental tool to quantitatively describe the properties of resonant systems. In particular, it enables the understanding of many photonic devices of current interest, such as photonic metasurfaces and nanostructured optical scatterers. In this contribution, we show that the scattering matrix of a photonic system is completely determined by its quasinormal modes, i.e., the self-sustaining electromagnetic excitations at a complex frequency. On the basis of temporal coupled-mode theory, we derive an expression for the expansion of the scattering matrix on quasinormal modes, which is directly applicable to an arbitrary number of modes and input/output channels. Our theory does not require any ad-hoc assumptions, such as the fitting of an additional nonresonant background. We validate and discuss the theoretical formalism with some illustrative examples. This demonstrates that the theory represents a powerful and predictive tool for calculating the highly structured spectra of resonant nanophotonic systems, and, at the same time, a key for unravelling the physical mechanisms at the heart of such intricate spectral structures.","photonic crystals; quasinormal modes; resonant states; scattering matrix; theoretical photonics","en","conference paper","IEEE","","","","","","","","","QN/Quantum Nanoscience","QN/Kuipers Lab","","",""
"uuid:11d242a9-e0de-465c-b44e-076250a9da53","http://resolver.tudelft.nl/uuid:11d242a9-e0de-465c-b44e-076250a9da53","Grow or store? Exploring metabolic decision making under feast/famine conditions using 13C tracer","Verhagen, K.J.A. (TU Delft OLD BT/Cell Systems Engineering); Gabriel Guedes da Silva, L. (TU Delft OLD BT/Cell Systems Engineering); van de Wijgaart, R. (TU Delft BT/Environmental Biotechnology); Kleerebezem, R. (TU Delft BT/Environmental Biotechnology); van Loosdrecht, Mark C.M. (TU Delft BT/Environmental Biotechnology); Wahl, S.A. (TU Delft OLD BT/Cell Systems Engineering)","","2017","Natural habitats of microorganisms are dynamic environments with non-continuous supply of carbon and energy sources, in which intermediate storage of substrates can increase competitiveness. Plasticicumulans acidivorans are polyhydroxybutyrate (PHB) accumulating bacteria enriched from activated sludge using carbon feast-famine cycles as selective pressure. Despite growing slowly, P. acidivorans outcompetes other bacteria by quickly taking up acetate and storing it intracellularly as PHB to later use it for growth. As soon as acetate is depleted, these bacteria immediately ‘switch’ their metabolism from PHB production to consumption entailing a very interesting regulatory challenge as parallel activity could lead to significant losses (futile cycling). While the stoichiometry for both feast and famine phases has been extensively described in literature, the switch regulation is not yet fully understood. To elucidate the responsible regulatory processes, an enrichment of P. acidivorans was studied using targeted intracellular metabolite analysis over time, with emphasis on the feast to famine switch. In combination with extracellular rates, the measured intracellular metabolite pools are used to design a labelling experiment to obtain actual intracellular fluxes (dynamic 13C flux analysis). Here the challenge is to create an isotopically non-stationary state (usually mediated by changing the substrate’s isotopic composition) to study the metabolic response in the transition from presence-to-absence of substrate.In this way, we aim to unravel the responsible regulatory mechanism governing the metabolic switch from storage-to-consumption and use this knowledge not only to understand its ecological relevance, but to also propose novel metabolic strategies for microbial cell factory design.","","en","poster","","","","","","","","","","","OLD BT/Cell Systems Engineering","","",""
"uuid:0e114b1a-367d-4017-81d7-819f0870b9a3","http://resolver.tudelft.nl/uuid:0e114b1a-367d-4017-81d7-819f0870b9a3","The Origin and Limit of Asymmetric Transmission in Chiral Resonators","Parappurath, N. (Center for Nanophotonics); Alpeggiani, F. (TU Delft QN/Kuipers Lab; Center for Nanophotonics; Kavli institute of nanoscience Delft); Kuipers, L. (TU Delft QN/Quantum Nanoscience; AMOLF; Kavli institute of nanoscience Delft); Verhagen, Ewold (AMOLF)","","2017","We observe that the asymmetric transmission (AT) through photonic systems with a resonant chiral response is strongly related to the far-field properties of eigenmodes of the system. This understanding can be used to predict the AT for any resonant system from its complex eigenmodes. We find that the resonant chiral phenomenon of AT is related to, and is bounded by, the nonresonant scattering properties of the system. Using the principle of reciprocity, we determine a fundamental limit to the maximum AT possible for a single mode in any chiral resonator. We propose and follow a design route for a highly chiral dielectric photonic crystal structure that reaches this fundamental limit for AT.","asymmetric transmission; coupled-mode theory; nanophotonics; optical chirality; photonic crystals","en","journal article","","","","","","","","","","QN/Quantum Nanoscience","QN/Kuipers Lab","","",""
"uuid:312f5a93-5a0a-406e-b697-a2798c75e3b5","http://resolver.tudelft.nl/uuid:312f5a93-5a0a-406e-b697-a2798c75e3b5","Breakwater design","Verhagen, H.J.; van den Bos, J.P.","","2017","For this book we have deliberately chosen that the text should follow a more or less logical design procedure for breakwaters. It follows the required design steps from the system level down to the individual crosssection level, and in time from conceptual design to construction. This systematic approach starts at the functional description of breakwaters, system analysis including side-effects and derivation of boundary conditions and continues to the actual design, first of the main armour layer and then of the rest of the cross section. It finishes with an overview of construction methods, materials and constructability issues. All existing breakwater types are discussed briefly but only the types that are frequently used all over theworld (i.e. rubble mound breakwaters, berm breakwaters and monolithic breakwaters) are treated in detail. It is expected that the reader will possess basic knowledge of hydraulic engineering. Only in some cases, where they are deemed useful for a proper understanding of the actual design process, some aspects of basic hydraulic engineering are presented.","","en","lecture notes","TU Delft, Department Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:9b0ec53c-a1ad-4543-bcbc-e60e8d94bd8d","http://resolver.tudelft.nl/uuid:9b0ec53c-a1ad-4543-bcbc-e60e8d94bd8d","Application of a greedy algorithm to military aircraft fleet retirements","Newcamp, Jeffrey (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Udluft, H. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","","2017","This article presents a retirement analysis model for aircraft fleets. By employing a greedy algorithm, the presented solution is capable of identifying individually weak assets in a fleet of aircraft with inhomogeneous historical utilization. The model forecasts future retirement scenarios employing user-defined decision periods, informed by a cost function, a utility function and demographic inputs to the model. The model satisfies first-order necessary conditions and uses cost minimization, utility maximization or a combination of the 2 as the objective function. This study creates a methodology for applying a greedy algorithm to a military fleet retirement scenario and then uses the United States Air Force A-10 Thunderbolt II fleet for model validation. It is shown that this methodology provides fleet managers with valid retirement options and shows that early retirement decisions substantially impact future fleet cost and utility.","Aircraft cost; Aircraft retirement; Fleet manager; Retirement model","en","journal article","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:5197b537-62bd-46bb-8398-24fb1c7f0f3c","http://resolver.tudelft.nl/uuid:5197b537-62bd-46bb-8398-24fb1c7f0f3c","Application of bamboo in mangrove rehabilitation projects","Harihar, S. (Business Analys, McKinsey & Company); Verhagen, H.J. (TU Delft Coastal Engineering)","","2017","Mangroves have proved to be an asset to coastlines owing to their various advantages in terms of coastal protection and stability. Along tropical coastlines, as mangrove tracts recede and threats of coastal erosion mount, mangrove rehabilitation projects are being seriously contemplated. The design of such projects, however, is in an incipient phase, and several technical and economic challenges are to be faced. The plantation and growth of mangroves requires a protected coastal environment with proper drainage of the soil substratum. Hence, in a sample design undertaken for a mangrove rejuvenation project along the eastern coast of Mumbai (India), various layouts have been studied for a protective coastal structure and drainage system. One such design uses bamboo pile walls in creating shielded compartments (with multiple compartmental layouts) for mangrove growth, along with bamboo drains. The bamboo-based structure was found to be environmentally and economically advantageous over other designs such as sand dykes, which are many times more expensive. Moreover, employing natural material such as bamboo helps the structure integrate with the developing mangrove habitat, allaying concerns about dismantling the structure after mangrove growth. A cost-minimising and eco-friendly bamboo structure such as this therefore promises to pave the way for large ecological projects in the future, spanning over 1000 ha.","","en","journal article","","","","","","","","2018-03-01","","","Coastal Engineering","","",""
"uuid:eba5c927-eaaa-414a-814c-bf67878e847d","http://resolver.tudelft.nl/uuid:eba5c927-eaaa-414a-814c-bf67878e847d","The origin and limit of asymmetric transmission in chiral resonators","Parappurath, N. (AMOLF); Alpeggiani, F. (TU Delft QN/Kuipers Lab; AMOLF); Kuipers, L. (TU Delft QN/Quantum Nanoscience; AMOLF); Verhagen, E. (AMOLF)","","2017","We develop a theoretical formalism which explains asymmetric transmission (AT) in chiral resonators from their eigenmodes. We derive a fundamental limit for AT and propose the design of a chiral photonic crystal offering 84% AT.","","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","","","","","QN/Quantum Nanoscience","QN/Kuipers Lab","","",""
"uuid:f8b77c28-dbb3-4f21-a582-7c48410f007f","http://resolver.tudelft.nl/uuid:f8b77c28-dbb3-4f21-a582-7c48410f007f","Time to retire: Indicators for aircraft fleets","Newcamp, Jeffrey (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","","2017","It is well known that aircraft fleets are aging alongside rising operations and support costs. Logisticians and fleet managers who better understand the milestones and timeline of an aging fleet can recognise potential savings. This paper outlines generalised milestones germane to military aircraft fleets and then discusses the causes that lead to retirement motivations. Then this paper develops a utility per cost metric for aging aircraft fleet comparison as a means for determining when to retire a fleet. It is shown that utility per cost is a pragmatic metric for gauging the desirability of an existing fleet because of naturally occurring zones. Historical data from the US Air Force's fleet are used to validate the existence of these zones. Lastly, this work highlights the need for increased vigilance during the waning years of a fleet's lifecycle and discusses the intricacies of asset divestment planning.","","en","journal article","","","","","","","","2018-12-01","","","Air Transport & Operations","","",""
"uuid:96e675a1-f1ba-46fc-b35b-0c5aff6bafd4","http://resolver.tudelft.nl/uuid:96e675a1-f1ba-46fc-b35b-0c5aff6bafd4","Fleet Management Decision Making With Individual Aircraft Tracking Data","Newcamp, Jeffrey (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","","2017","Individual aircraft tracking data can be used by aircraft fleet managers to detect patterns in historical usage as a means to aid aging aircraft decision-making. This work tackles two aspects of applying these tracking data: investigating retirement patterns and assessing how base assignment can impact usage. The A-10, C-17 and F-35 acquisition schedules were analyzed to set the expectation for retirement forecasting. Then three types of retirement patterns were assessed - the Cliff, Multi-Step and Ramp - and the merits of each are presented. Equivalent flight hours were used as an approximation for fatigue life expended in the analysis of retirement patterns in tracking data. A candidate set of tracking data was investigated to uncover base usage variations across a network. The dissimilar mission type requirements at each base led to unique loading profiles for aircraft at each of the bases in the network. These findings lead to the natural conclusion that base assignment can be used as a way to modify the loading accumulation on individual tail numbers and across a fleet.","","en","conference paper","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:b2134012-902a-48ee-92fb-34f26248ab3b","http://resolver.tudelft.nl/uuid:b2134012-902a-48ee-92fb-34f26248ab3b","An advanced design project on ‘Port Engineering and Maritime Works’ in teaching future engineers","Guillaume Carpentier, G. (ESITC Caen); Piero Silva, P. (Artelia); Allsop, W (University of Southampton); Mouazé, D. (University of Caen); Verhagen, H.J. (TU Delft Coastal Engineering); Gautier-Chevreux, L. (ESITC Caen); Bagieu, M. (ESITC Caen)","","2017","This paper describes a unique design project devised to teach and apply technical skills in port design, but also in the practical cooperation between students in a realistic design project. The 4-week long project now involves students of up to 19 nationalities from 7-10 universities, and has been based each year on real design projects. Student teams of 8-10 per team have to deliver a realistic design to examiners from both academia and industry. The students select from a number of optional modules. No student can take all of them, so appreciation of the skills available within the team are important.","","en","conference paper","ICE Publishing","","","","","","","","","","Coastal Engineering","","",""
"uuid:f7646f3b-9a99-4207-97a6-20ef83c6a571","http://resolver.tudelft.nl/uuid:f7646f3b-9a99-4207-97a6-20ef83c6a571","A Statistical analysis on the system performance of a bluetooth low energy indoor positioning system in a 3D environment","Haagmans, G. G.; Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Voûte, R.L. (TU Delft OLD Department of GIS Technology; TU Delft OLD Urban Design); Verbree, E. (TU Delft OLD Department of GIS Technology)","","2017","Since GPS tends to fail for indoor positioning purposes, alternative methods like indoor positioning systems (IPS) based on Bluetooth low energy (BLE) are developing rapidly. Generally, IPS are deployed in environments covered with obstacles such as furniture, walls, people and electronics influencing the signal propagation. The major factor influencing the system performance and to acquire optimal positioning results is the geometry of the beacons. The geometry of the beacons is limited to the available infrastructure that can be deployed (number of beacons, basestations and tags), which leads to the following challenge: Given a limited number of beacons, where should they be placed in a specified indoor environment, such that the geometry contributes to optimal positioning results? This paper aims to propose a statistical model that is able to select the optimal configuration that satisfies the user requirements in terms of precision. The model requires the definition of a chosen 3D space (in our case 7 × 10 × 6 meter), number of beacons, possible user tag locations and a performance threshold (e.g. required precision). For any given set of beacon and receiver locations, the precision, internal-and external reliability can be determined on forehand. As validation, the modeled precision has been compared with observed precision results. The measurements have been performed with an IPS of BlooLoc at a chosen set of user tag locations for a given geometric configuration. Eventually, the model is able to select the optimal geometric configuration out of millions of possible configurations based on a performance threshold (e.g. required precision).","3D space; Bluetooth low energy; Indoor positioning system; optimal configuration; precision; system performance; theoretical design computations","en","conference paper","ISPRS","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:53b95fc5-7e79-4042-8c0d-b87b6f95a84d","http://resolver.tudelft.nl/uuid:53b95fc5-7e79-4042-8c0d-b87b6f95a84d","Multi-criteria weighted order based maintenance decision making","Dhanisetty, V.S.V. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","","2017","Decision making in daily maintenance requires consideration of multiple factors. The importance of each of the factors fluctuates depending on the repair scenario and the needs of the maintainer. In order to include the prioritisation of multiple criteria, a weighted decision making model is developed. The model evaluates all repair options and rates them individually for three decision making factors: survivability, cost, and downtime. The factor ratings are aggregated using designated weights, resulting in a final score for each of the repair options. This type of decision making evaluation provides flexibility in considering repair options that may otherwise be deemed unfavourable because of one factor. Case study results show one of five considered options as the best, for three of the four weight sets. The resulting best option of the other weight set demonstrates that definition of best repair is dependent on the priority of decision factors.
The system concept is a widely-used concept in research and practice. Already in the 50s of the previous century, a community was created to investigate interrelationships between domains and create a theory surpassing and comparing domains. The General Systems Theory (GST) community has tried to come up with such a theory for several decades. The ambition has grown more realistic in the years after, recognizing that an all-encompassing theory would not be possible. Since then, systems research was aimed at generating useful and usable approaches to compare and interrelate domains, thus creating a trans-disciplinary approach to enable description and analysis of large, and even complex, systems. The concept of systems, however, is often loosely used. Levels of abstraction are neglected, and interrelationships between systems ignored. In this paper, the concept of system is put in historical context, and further elaborated upon in the context of complex and trans-disciplinary systems. Two examples of transdisciplinary systems are presented and discussed to illustrate the use of the system concept.","Aircraft dispatch; Aircraft maintenance; Decision support; Multi-criteria decision making; Root cause analysis","en","conference paper","IOS Press","","","","","","","","","","Air Transport & Operations","","",""
"uuid:bbb4361e-71fa-4a5a-bfd2-435b02e3a7c3","http://resolver.tudelft.nl/uuid:bbb4361e-71fa-4a5a-bfd2-435b02e3a7c3","Component-Based Data-Driven Predictive Maintenance to Reduce Unscheduled Maintenance Events","Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations); de Boer, L.W.M.","Chen, C.H. (editor); Trappey, A.C. (editor); Peruzzini, M. (editor); Stjepandić, J. (editor); Wognum, N. (editor)","2017","style=""margin: 0cm 0cm 10pt;"">Costs associated with unscheduled and preventive maintenance can contribute significantly to an airline's expenditure. Reliability analysis can help to identify and plan for maintenance events. Reliability analysis in industry is often limited to statistically based approaches that incorporate failure times as the primary stochastic variable, with additional strict assumptions regarding independence of events and underlying distributions of failure phenomena. This foregoes the complex nature of aircraft operations, where a whole range of operational factors may influence the probability of occurrence of a maintenance event. The aim of this research is to identify operational factors affecting component reliability and to assess whether these can be used to reduce the number of unscheduled occurrences (i.e. failures). To do so, a data-driven approach is adopted where historical operational and maintenance data is gathered and analysed to identify operational factors with a measurable influence on maintenance event occurrence. Both time-independent and time-dependent Proportional Hazard Models (PHMs), models which incorporate operational factors as covariates, are employed to generate reliability estimates. Results obtained from analysing historical data of a set of ten components with respect to unscheduled removals indicates that adopting new maintenance schedules, derived from the proposed reliability models, could reduce the number of unscheduled occurrences by approximately 37%. The potential benefits of adopting the proposed strategy are extensive. Nonetheless, numerous assumptions have been introduced to overcome challenges imposed by the complex nature of the data. To overcome these challenges, recommendations are made for future development of the proposed approach","Aircraft dispatch; Aircraft maintenance; Decision support; Multi-criteria decision making; Root cause analysis","en","conference paper","IOS Press","","","","","","","","","","Air Transport & Operations","","",""
"uuid:47556c25-e634-4fcc-9fdf-c2e82d5a5c40","http://resolver.tudelft.nl/uuid:47556c25-e634-4fcc-9fdf-c2e82d5a5c40","Quasinormal-Mode Expansion of the Scattering Matrix","Alpeggiani, F. (TU Delft QN/Kuipers Lab; AMOLF; Kavli institute of nanoscience Delft); Parappurath, N. (AMOLF); Verhagen, E. (AMOLF); Kuipers, L. (TU Delft QN/Quantum Nanoscience; AMOLF; Kavli institute of nanoscience Delft)","","2017","It is well known that the quasinormal modes (or resonant states) of photonic structures can be associated with the poles of the scattering matrix of the system in the complex-frequency plane. In this work, the inverse problem, i.e., the reconstruction of the scattering matrix from the knowledge of the quasinormal modes, is addressed. We develop a general and scalable quasinormal-mode expansion of the scattering matrix, requiring only the complex eigenfrequencies and the far-field properties of the eigenmodes. The theory is validated by applying it to illustrative nanophotonic systems with multiple overlapping electromagnetic modes. The examples demonstrate that our theory provides an accurate first-principles prediction of the scattering properties, without the need for postulating ad hoc nonresonant channels.","","en","journal article","","","","","","","","","","QN/Quantum Nanoscience","QN/Kuipers Lab","","",""
"uuid:b1e1cddb-67ab-4141-98b7-ffcf73282bfe","http://resolver.tudelft.nl/uuid:b1e1cddb-67ab-4141-98b7-ffcf73282bfe","Spectral EMG changes in Cervical Dystonia patients and the influence of botulinum toxin treatment","Nijmeijer, S.W.R. (Universiteit van Amsterdam); de Bruijn, E. (TU Delft Biomechatronics & Human-Machine Control); Verhagen, R. (Universiteit van Amsterdam); Forbes, P.A. (TU Delft Biomechatronics & Human-Machine Control); Kamphuis, D.J. (Reinier de Graaf Gasthuis); Happee, R. (TU Delft Intelligent Vehicles); Tijssen, M.A.J. (Rijksuniversiteit Groningen); Koelman, J.H.T.M. (Universiteit van Amsterdam)","","2017","Botulinum toxin (BoNT) injections in the dystonic muscles is the preferred treatment for Cervical Dystonia (CD), but the proper identification of the dystonic muscles remains a challenge. Previous studies showed decreased 8–14 Hz autospectral power in the electromyography (EMG) of splenius muscles in CD patients. Cumulative distribution functions (CDF’s) of dystonic muscles showed increased CDF10 values, representing increased autospectral powers between 3 and 10 Hz, relative to power between 3 and 32 Hz. In this study, we evaluated both methods and investigated the effects of botulinum toxin. Intramuscular EMG recordings were obtained from the splenius, semispinalis, and sternocleidomastoid muscles during standardized isometric tasks in 4 BoNT-naïve CD patients, 12 BoNT-treated patients, and 8 healthy controls. BoNT-treated patients were measured 4–7 weeks after their last BoNT injections and again after 11–15 weeks. We found significantly decreased 8–14 Hz autospectral power in splenius muscles, but not in the semispinalis and sternocleidomastoid muscles of CD patients when compared to healthy controls. CDF10 analysis was superior in demonstrating subtle autospectral changes, and showed increased CDF10 values in all studied muscles of CD patients. These results did not change significantly after BoNT injections. Further studies are needed to investigate the origin of these autospectral changes in dystonia patients, and to assess their potential in muscle selection for BoNT treatment","cervical dystonia; botulinum toxin; EMG; autospectral analysis; muscle selection","en","journal article","","","","","","","","","","","Biomechatronics & Human-Machine Control","","",""
"uuid:f2327953-cc7b-4ec2-bf48-0caeed66503e","http://resolver.tudelft.nl/uuid:f2327953-cc7b-4ec2-bf48-0caeed66503e","Contextualising aircraft maintenance documentation","Koornneef, H. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","","2017","The use of documentation for task support in aircraft line maintenance is still mostly paper-based, which is slow, burdensome and prone to error. This paper provides an overview of the issues associated with the use of paper-based documentation in aircraft line maintenance and describes the development of a novel concept for contextualised documentation to address these issues. Using ontology-based data access, the system is able to retrieve relevant documents approximately twice as fast as existing relational database systems and provides support for a wide variety of file types. Limitations of the developed system are software vendor dependency, compatibility issues between integrated software solutions and lack of support for automatic mappings. Nevertheless, the developed system provides a proof of concept for a mobile tool to overcome the weaknesses of maintenance documentation in line maintenance, working towards increased operational efficiency, reduction of human factor induced maintenance errors and reduced paper consumption.","Aircraft line maintenance; Contextualised documentation; Human factors; Maintenance efficiency; Ontology-based data access; Paperless","en","journal article","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:339741e7-5e53-4f6f-9417-4e6c94f00a51","http://resolver.tudelft.nl/uuid:339741e7-5e53-4f6f-9417-4e6c94f00a51","An efficient implementation of fixed failure-rate ratio test for GNSS ambiguity resolution","Hou, Y.; Verhagen, S. (TU Delft Mathematical Geodesy and Positioning); Wu, J","","2016","Ambiguity Resolution (AR) plays a vital role in precise GNSS positioning. Correctly-fixed integer ambiguities can significantly improve the positioning solution, while incorrectly-fixed integer ambiguities can bring large positioning errors and, therefore, should be avoided. The ratio test is an extensively used test to validate the fixed integer ambiguities. To choose proper critical values of the ratio test, the Fixed Failure-rate Ratio Test (FFRT) has been proposed, which generates critical values according to user-defined tolerable failure rates. This contribution provides easy-to-implement fitting functions to calculate the critical values. With a massive Monte Carlo simulation, the functions for many different tolerable failure rates are provided, which enriches the choices of critical values for users. Moreover, the fitting functions for the fix rate are also provided, which for the first time allows users to evaluate the conditional success rate, i.e., the success rate once the integer candidates are accepted by FFRT. The superiority of FFRT over the traditional ratio test regarding controlling the failure rate and preventing unnecessary false alarms is shown by a simulation and a real data experiment. In the real data experiment with a baseline of 182.7 km, FFRT achieved much higher fix rates (up to 30% higher) and the same level of positioning accuracy from fixed solutions as compared to the traditional critical value.","GNSS; GPS; ambiguity resolution; ratio test; failure rate; fix rate; OA-Fund TU Delft","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:3ea1cf75-35ff-4add-8c9b-3750c3ac5569","http://resolver.tudelft.nl/uuid:3ea1cf75-35ff-4add-8c9b-3750c3ac5569","Accidental use of earth bodies as flood defence: The Vlaardingen case study","Verhagen, H.J. (TU Delft Coastal Engineering)","","2016","An overview of the upgrade of the railroad dike in Vlaardingen to a full sea defence, creating in this way a multifunctional flood defence.","Multifunctional sea defence; dikes; Vlaardingen","en","report","Delft University of Technology","","","","","","","","","","Coastal Engineering","","",""
"uuid:fde08f68-599d-4f53-b96e-f6d92a820fea","http://resolver.tudelft.nl/uuid:fde08f68-599d-4f53-b96e-f6d92a820fea","Closure works: Interactive professional course","Verhagen, H.J.","","2016","For this book we have deliberately chosen that the text should follow a more or less logical design procedure for closure dams. It is emphasized that only the construction aspect of stopping the water movement is considered in this book. This means that only the closing operation itself is treated; the transformation of the closing dam into a permanent structure like an embankment is beyond the scope of this book.","coastal engineering; closure dams; closure works","en","lecture notes","TU Delft, Department Hydraulic Engineering; VSSD","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:31ebc035-b3a6-44e7-880e-32a6443c2cbb","http://resolver.tudelft.nl/uuid:31ebc035-b3a6-44e7-880e-32a6443c2cbb","Measuring compliance during aircraft (Component) redeliveries at KLM engineering & maintenance","Burhani, Shahir; Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","","2016","Aircraft and aircraft components are redelivered to the next operator or owner during the phase-out process. During this process the operator is required by law and contract requirements to show compliance with maintenance procedures. At KLM E&M the phase-out documentation process is under increasing scrutiny as the number of aircraft phase-outs is assumed to rise in the coming years. The compliance process is investigated in order to measure, analyze and improve compliance with regard to maintenance data and record keeping during aircraft (component) redeliveries. For this purpose a benchmarking study is conducted to identify process bottlenecks. This study proved that in the case of KLM E&M phase-out, Landing Gears Life Limited Parts (LG LLPs) form the major bottleneck. Subsequently, an aircraft compliance model is developed to support the compliance cycle. As a case study, the documentation of LG LLPs of KLM's Boeing B737 aircraft fleet is investigated in this research. LG LLPs which are most frequently interchanged and installed on the nose gear miss the highest percentage of documentation necessary to prove back-to-birth traceability (a traceable history of a component over its life), which is a necessary feature from a phase-out perspective. On the basis of the compliance model and the observed data, several improvements to the phase-out process are proposed.","Aircraft maintenance; Phase-out; Traceability","en","conference paper","IOS Press","","","","","","","","","","Air Transport & Operations","","",""
"uuid:a22fac11-d1eb-42cb-8633-7e211b09bf3d","http://resolver.tudelft.nl/uuid:a22fac11-d1eb-42cb-8633-7e211b09bf3d","Damage to grass dikes due to wave overtopping","Le, H.T. (Thuyloi University); Verhagen, H.J. (TU Delft Coastal Engineering); Vrijling, J.K. (TU Delft Hydraulic Structures and Flood Risk)","","2016","Grass covers have been applied as an effective measure for protecting river levees and sea dikes. We conducted experiments to show how roots considerably improve the shear strength of soil on dike slopes. Roots of 1-year-old Bermuda and Carpet grass may increase the total shear strength of up to 20 kPa. Exposed to severe overtopping flow, dike slopes may possibly fail in various manners including ‘head-cut’, ‘roll-up’ and ‘collapse’. The ratio between shear strength of the grass cover and its subsoil layer would get a value of two to distinguish the first two manners and would be zero for the last one. To some extent, the findings contribute to the basis for thoughtfully investigating the strength and failure mechanism of grass-covered slopes.","Grass cover; Root tensile strength; Sea dikes; Soil cohesion; Wave overtopping","en","journal article","","","","","","","","2018-01-01","","","Coastal Engineering","","",""
"uuid:ebeeacb1-5a54-445c-9b8c-b9dcee48f02c","http://resolver.tudelft.nl/uuid:ebeeacb1-5a54-445c-9b8c-b9dcee48f02c","Correlation of Mission Type to Cyclic Loading as a Basis for Agile Military Aircraft Asset Management","Newcamp, Jeffrey (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","","2016","Military attack aircraft are susceptible to the harmful effects of widespread fatigue damage caused by cyclic loading of structural components, which leads to airframe retirement. Modern structural health monitoring techniques use a multitude of sensors and high data collection rates. Some legacy airframes, which are most susceptible to fatigue damage due to their age, possess a counting accelerometer technology with few sensors and low data capture rates. The data provided by these 40-year old devices are crucial to understanding fleet health and can be used to extend structural lifetime for aging aircraft. Existing literature has addressed counting accelerometer usefulness, but a profound three-decade gap in research has led to a chasm between the current wealth of available data and tool development for utilizing those data. This research uses 11 years of A-10 Thunderbolt II counting accelerometer data to prove that mission type, mission duration and aircraft type correlate to aircraft loading patterns. It is shown that a mission type model can therefore influence fleet management strategies and the structural lifetime extension for aging aircraft","Military aircraft; Mission type; Structural lifetime; Accelerometer","en","journal article","","","","","","","","2018-12-31","","","Air Transport & Operations","","",""
"uuid:17ab2c88-9b8b-4ee7-a9b9-875a7d1978c8","http://resolver.tudelft.nl/uuid:17ab2c88-9b8b-4ee7-a9b9-875a7d1978c8","Aging Military Aircraft Landscape: A Case for End-of-Life Fleet Optimization","Newcamp, Jeffrey (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","","2016","Military aircraft fleets are continuing to age despite increased structural integrity concerns and rising maintenance costs. Aircraft are not being replaced or retired in large numbers but are instead having their lives extended beyond their original design service lives. Because aging aircraft cost more to maintain, this additional burden on air forces is a forcing function for smarter approaches to enhanced structural health monitoring. As data recorder technology has improved and recording capacity has increased, structural health monitoring tools have become more important in understanding aircraft life. Accrued historical data present opportunities for end-of-life fleet optimization. This paper provides a thorough review of the aging aircraft problem and suggests a direction for future end-of-life fleet optimization research. The suggestions include the alteration of aircraft utilization, optimization for aircraft basing and the prediction of structural fatigue, all of which can enable the realization of fleet-wide cost savings.","Aircraft Monitoring; Fleet Optimization; End-of-Life; Aging Aircraft","en","conference paper","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:d73c10e9-7027-4894-bbfc-d30ea33ac259","http://resolver.tudelft.nl/uuid:d73c10e9-7027-4894-bbfc-d30ea33ac259","Multi-level repair decision-making process for composite structures","Dhanisetty, V.S.V. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","","2016","This paper details the development of a decision-making model that evaluates the multiple repair levels that a composite structure can undergo, each with its inherent achievable survivability and consequence to operations in terms of availability, costs, and scheduling. The goal of this model is to provide the maintainer an integrated approach to all feasible repair solutions within the operational and structural integrity constraints, applicable to any given damage levels found during monitoring. At its core, the model incorporates various stochastic processes to model different types of repairable behavior: the non-homogeneous Poisson process and the renewal process. A case study on the carbon-fiber reinforced polymer flaps of a Boeing 777 has been performed to verify and validate the proposed decision-making model. With the case study providing the means for application of the model in an operational context, a standardized decision making process was delivered that is adaptable to any given failure scenario and implementable in practice.","Composites, Aircraft structures; Decision making; Maintenance repair; cost benefit analysis; Survivability","en","conference paper","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:180b7106-0dec-4ec8-bebf-9ea34ab156df","http://resolver.tudelft.nl/uuid:180b7106-0dec-4ec8-bebf-9ea34ab156df","Automating Contextualized Maintenance Documentation","Koornneef, H. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","Borsato, M. (editor); Wognum, N. (editor); Peruzzini, M. (editor); Stjepandić, J. (editor); Verhagen, W.J.C. (editor)","2016","Currently, task support information in aircraft maintenance is mostly provided using paper-based solutions, which are burdensome, slow and prone to error. Aircraft maintenance documentation contains vast amounts of information irrelevant for the task at hand and even for the simplest tasks multiple documents need to be consulted. Next to these issues with the documentation itself, Aircraft Maintenance Technicians (AMTs) have very limited on-site access to support information. These factors lead to 15–20% of hands-on-aircraft time being wasted on acquiring the right information or not using maintenance documentation for task support at all, risking maintenance error. This paper describes the development of a system for a first level of contextualization of maintenance documentation to simplify the retrieval of task support information. Combining a tailor-made ontology with a relational database system for Ontology-Based Data Access (OBDA), maintenance documents relevant to a specific aircraft registration mark can be identified. The system contributes to the research field of knowledge management by using OBDA for selecting relevant maintenance documents stored in a regular file folder. Future work will focus on increasing the level of contextualization, development of a mobile tool for on-site access and prototype verification and validation in an operational environment.","Aircraft maintenance; maintenance efficiency; contextualized documentation; ontology-based data access; human factors; mobile tools","en","book chapter","IOS Press","","","","","","","","","","Air Transport & Operations","","",""
"uuid:42aaa1b4-f738-451c-8341-50f3c91c00d3","http://resolver.tudelft.nl/uuid:42aaa1b4-f738-451c-8341-50f3c91c00d3","A Decentralized Approach to Formation Flight Routing","Visser, H.G. (TU Delft Air Transport & Operations); Santos, Bruno F. (TU Delft Air Transport & Operations); Verhagen, C.M.A.","","2016","This paper describes the development of an optimization-based cooperative planning system for the efficient routing and scheduling of flight formations. This study considers the use of formation flight as a means to reduce the overall fuel consumption of civil aviation in long-haul operations. It elaborates on the operational implementation of formation flight, particularly focusing on formation flight routing. A completely decentralized approach is presented, meaning that formation flight is not anticipated pre-flight and is not subjected to any predefined routing restrictions. A greedy communication scheme is defined through which all participating aircraft are allowed to communicate with neighboring aircraft in order to establish flight formations. The communication range of aircraft is used as a system parameter to control the allowed communications. A constraint on formation flight induced additional flight time is introduced in order to suppress the occurrence of large detours in the assembly of flight formations. A transatlantic case study is presented that contains 347 eastbound flights. Assuming a 10% fuel flow reduction for any trailing aircraft in formation, overall obtainable fuel savings were estimated at 4.3% at the expense of an additional flight time of 10.3 minutes per flight on average. In this transatlantic long-haul scenario, a formation flight usage rate of 73% was realized.","flight formations; flight routing; decentralised planning; fuel-efficiency","en","conference paper","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:d07b8cc4-0af1-450e-9f8a-30a480f364dc","http://resolver.tudelft.nl/uuid:d07b8cc4-0af1-450e-9f8a-30a480f364dc","Spatial tools for diagnosing the degree of safety and liveability, and to regenerate urban areas in The Netherlands","van Nes, A. (TU Delft Spatial Planning and Strategy); López, Manuel (Rotterdam University of Applied Sciences); de Bonth, L.F.J.M.; Verhagen, D.J.; Waayer, Simone","Nijhuis, Steffen (editor); Zlatanova, Sisi (editor); Dias, Eduardo (editor); van der Hoeven, Frank (editor); van der Spek, Stefan (editor)","2016","This contribution describes the tool Social Safe Urban Design (SSUD), seen
together with socio-spatial and linguistic challenges when applying space syntax in the regenerating of problem urban areas. The Space Syntax jargon is technical and needs to be translated into a language understandable and acceptable to stakeholders who are responsible for the implementation of improvement strategies acceptable for the users of a neighbourhood. Moreover, the degree of public-private interface between buildings and streets needs to be incorporated in the Space Syntax analyses. As it turns out from spatial analyses and crime registrations, there is a correlation between crime and anti-social behaviour and the spatial layout of built environments in the investigated eight pilot cases. Simultaneously, there is also a challenge to come up with locally and globally functioning spatial solutions for reducing opportunities for crime and anti-social behaviour for the neighbourhoods. Proposed solutions for three of these neighbourhoods are presented in this
contribution.","Space syntax; Urban regeneration; Network configuration; Crime; Communicative planning","en","book chapter","TU Delft OPEN Publishing","","","","","","","","","","Spatial Planning and Strategy","","",""
"uuid:97d034ec-05c2-41c8-a00a-9bef925e8980","http://resolver.tudelft.nl/uuid:97d034ec-05c2-41c8-a00a-9bef925e8980","Aircraft Disposal and Recycle Cost Estimation","Zhao, X. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","Borsato, M. (editor); Wognum, N. (editor); Peruzzini, M. (editor); Stjepandić, J. (editor); Verhagen, W.J.C. (editor)","2016","The present study develops a method for the sake of evaluating Disposal and Recycle (D&R) cost in view of the increasing demand in aircraft retirement. Firstly, a process model is extracted. The subordinated cost elements are also identified. Next, the cost aggregations based on the D&R process steps are discussed. Moreover, it proposes an economic indicator to support the determination of the aircraft D&R strategies. The indicator is used to evaluate the economic performance and to facilitate the trade-off studies among different D&R scenarios. This analysis is demonstrated on two aircraft types with two scenarios. In addition, sensitivity analysis evaluating the impact of the salvage value, residual value, D&R cost, and the learning factor is performed. It is found that the engine D&R possesses more economic gains than that of the aircraft. The salvage value and residual value are the main factors which influence the D&R economic performance.","Cost analysis; aircraft disposal and recycle process; disposal and recycle economic indicator","en","book chapter","IOS Press","","","","","","","","","","Air Transport & Operations","","",""
"uuid:f46c67bb-88a6-463a-ae8b-3dc8a2cf588e","http://resolver.tudelft.nl/uuid:f46c67bb-88a6-463a-ae8b-3dc8a2cf588e","A New Symmetrical Unit for Breakwater Armour: First Tests","Salauddin, M.; Broere, A.; Van der Meer, J.W.; Verhagen, H.J.; Bijl, E.","","2015","A new and symmetrical single layer armour unit, the crablock, has been designed in the UAE. One breakwater was reconstructed with crablock, but very limited testing had been performed. Just to become more acquainted with this new unit, pre-competitive research at a university has been performed, which is the subject of this paper. Being a new armour unit, the placement was investigated first. Then physical model tests were performed in a wave flume to come up with results on stability and wave overtopping. Moreover, to determine the interlocking properties of armour units, pull tests were also conducted in this research. Those results are not part of this paper. Test results on stability showed that the longer waves affected the armour layer a little more, with larger movements and earlier displacements. Packing density as well as placement pattern showed no influence on wave overtopping. The overtopping tests gave larger overtopping than expected, which might be due to the fairly steep 1:30 foreshore.","crablock; interlocking; wave overtopping; armour unit","en","conference paper","ASCE - COPRI","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:c0a57b0f-5ebf-49f7-a104-0359759e9547","http://resolver.tudelft.nl/uuid:c0a57b0f-5ebf-49f7-a104-0359759e9547","Numerical modelling of wave reflection and transmission in vertical porous structures","Van den Bos, J.P.; Verhagen, H.J.; Kuiper, C.","","2015","This paper presents the results of a systematic validation of numerical simulation of reflection and transmission of rubble-mound breakwater structures. The aim of the study is to provide a body of validation measurements for increasingly complex situations, starting simple and building up the comlexity in terms of breawater geometry, wave condtions and numverical simulation models. The predictions from a set of three differen numerical models were compared against measurements from small scale physical model tests. The results of he comparision and the achieved level of accuracy are rported. Finally, a hypothetical application for the desighn of rublle-mound breakwaters is presented.","breakwater; porous structure; permeability","en","conference paper","ASCE - COPRI","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:d9591f49-da1a-4b75-bc55-5cd92dbcf91d","http://resolver.tudelft.nl/uuid:d9591f49-da1a-4b75-bc55-5cd92dbcf91d","Aircraft bi-level life cycle cost estimation","Zhao, X.; Verhagen, W.J.C.; Curan, R.","","2015","n an integrated aircraft design and analysis practice, Life Cycle Cost (LCC) is essential for decision making. The LCC of an aircraft is ordinarily partially estimated by emphasizing a specific cost type. However, an overview of the LCC including design and development cost, production cost, operating cost and disposal cost is not provided. This may produce biased cost estimates. Moreover, aircraft LCC estimation is largely dependent on the availability of input parameters. It is often a problem for the analyst to supply a limited group of data into a detailed cost estimation process. Therefore, it is necessary to provide flexibility in conducting both high level and detail level LCC assessments based on the data accessibility. An input-dependent bi-level LCC estimation method is proposed. It illustrates the comprehensive estimation of the cost elements in the LCC with clearly defined high level and detail level analyses to form the final cost. Knowledge of the product and the life cycle process are structured based on a pre-defined meta model and logic rules. Cost is then evaluated by traversing the meta model linked with computing capabilities. This method is applied on a case study concerning A330-200 aircraft. With the support of weight estimation and bottom-up process-based parametric cost estimation methods, it builds up a practical costing approach in quantifying the influence of LCC to the product life cycle.","Life Cycle Cost; cost estimation; design for cost","en","book chapter","IOS Press","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:412d49a0-2898-4622-bf3f-d7382b18a970","http://resolver.tudelft.nl/uuid:412d49a0-2898-4622-bf3f-d7382b18a970","The effect of a dragging anchor on a horizontal layer of rockfill: A Prototype and a Scale Model Test","Crum, S.; Van der Hoeven, M.L.E.B.; Krouwel, L.P.H.C.; Verhagen, H.J.","","2015","Quantifying the penetration depth of a dragging anchor on a horizontal layer of rockfill provides the possibility to optimize the layer thickness of rockfill layers with a protective function. Current research on this subject is limited and is often aimed at anchor capacities in sand and clay. Penetration behaviour in rockfill is mainly investigated for protections with a limited width. Anchor dragging tests carried out for a canal expansion project show that as the rock size increases, the penetration depth and the holding capacity of the anchor decrease. A semi-empirical prediction formula is derived. An additional series of scaled down tests shows that the process of anchor drag in rockfill is scalable, as long as all aspects of the trial design are taken into account. This provides possibilities for accessible further research, expanding on the prediction of penetration depth and further anchor behaviour in different types of rockfill.","anchor; anchor dragging; bed protection","en","conference paper","ASCE - COPRI","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:330f0d49-99ac-4e8a-b8b4-3088c3d54acf","http://resolver.tudelft.nl/uuid:330f0d49-99ac-4e8a-b8b4-3088c3d54acf","How to teach engineers to interact in a political decision making environment","López Royo, M.; Burgmeijer, M.; Verhagen, H.J.","","2015","Sectoral professionals, like coastal engineers, need to know how to cooperate in a multi-disciplinary environment, as well as how to present substantial information to (political) decision makers. In order to train (coastal engineering) students in this matter, Unesco-IHE and TU Delft have in their curriculum an Integrated Coastal Zone Management Seminar. Because there is also a demand for such a seminar from outside the normal student population, this seminar is also open for external participants, like tourist resort developers, ecologists as well as policy support officials, who are in need to learn how to present to decision makers the various development options in a coastal zone. This paper will give an overview of the nearly 25 years of experience we have collected in giving this seminar in Delft and Overseas. It is written from the learning perspective of a professional who attends the ICZM Seminar, while remarking the challenges and goals expected to be achieved.","coastal zone management; training","en","conference paper","ICE (Institution of Civil Engineers)","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:18619c07-80d1-4362-b398-2425c983eba6","http://resolver.tudelft.nl/uuid:18619c07-80d1-4362-b398-2425c983eba6","Numerical evaluation of stability methods for rubble mound breakwater toes","Verpoorten, S.P.K.; Ockeloen, W.J.; Verhagen, H.J.","","2015","Since 1977 dedicated studies are made to the stability of rubble mound break-water toes under wave attack. A large number of stability methods is available, but prediction accuracy is low and validity ranges are too small for use in prac-tice. In this research the decoupled model approach is used to evaluate predic-tion capacity of existing toe stability methods. The approach uses numerical model IH-2VOF for a prediction of stability. Review of the model showed that it is highly sensitive to stone properties and that turbulence was not modelled. Un-der the assumption that the latter is not of major importance, calibration of mo-tion formulae against physical measurements and evaluation of the stability methods was performed. The decoupled model approach appeared to give good stability predictions. Validity limits of the stability methods seemed to be too strict. A ranking of stability methods was made. Future validation should con-firm the results before incorporation in design manuals.","breakwater; toe structure; toe stability","en","conference paper","ASCE - COPRI","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:a9a1489c-8870-4336-8393-6a59ec4993d8","http://resolver.tudelft.nl/uuid:a9a1489c-8870-4336-8393-6a59ec4993d8","A methodological approach for the optimisation of the product development process by the application of design automation","Mulder, B.; La Rocca, G.; Schut, J.; Verhagen, W.J.C.","","2015","A short lead time of the Product Development Process (PDP) is an important competitive advantage for companies. Design automation solutions provide a means to reduce the lead time and improve quality, but their development requires some investment. Before a company can commit to the development of an automation initiative, it requires an estimation of the expected costs and benefits. The objective of this research is the development of a decision support system, based on multi objective optimization techniques and Discrete Event Simulation, to evaluate the effect of introducing automation solutions in a given PDP. The system is able to generate Pareto fronts showing optimum combinations of lead time reductions versus investment cost for automation. For each of the solutions on the Pareto front, the system provides the suggested list of PDP activities to be automated and their level of automation. The system functionality has been successfully demonstrated by means of a use case concerning the PDP of an aircraft component.","","en","conference paper","CEAS","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:15005cde-99c1-48c3-915c-1c930d86afba","http://resolver.tudelft.nl/uuid:15005cde-99c1-48c3-915c-1c930d86afba","Robust BRCA1-like classification of copy number profiles of samples repeated across different datasets and platforms","Schouten, P.C.; Grigoriadis, A.; Kuilman, T.; Mirza, H.; Watkins, J.A.; Cooke, S.A.; Van Dyk, E.; Severson, T.M.; Rueda, O.M.; Hoogstraat, M.; Verhagen, C.; Natrajan, R.; Chin, S.F.; Lips, E.H.; Kruizinga, J.; Velds, A.; Nieuwland, M.; Kerkhoven, R.M.; Krijgsman, O.; Vens, C.; Peeper, D.; Nederlof, P.M.; Caldas, C.; Tutt, A.N.; Wessels, L.F.A.; Linn, S.C.","","2015","Breast cancers with BRCA1 germline mutation have a characteristic DNA copy number (CN) pattern. We developed a test that assigns CN profiles to be ‘BRCA1-like’ or ‘non-BRCA1-like’, which refers to resembling a BRCA1-mutated tumor or resembling a tumor without a BRCA1 mutation, respectively. Approximately one third of the BRCA1-like breast cancers have a BRCA1 mutation, one third has hypermethylation of the BRCA1 promoter and one third has an unknown reason for being BRCA1-like. This classification is indicative of patients' response to high dose alkylating and platinum containing chemotherapy regimens, which targets the inability of BRCA1 deficient cells to repair DNA double strand breaks. We investigated whether this classification can be reliably obtained with next generation sequencing and copy number platforms other than the bacterial artificial chromosome (BAC) array Comparative Genomic Hybridization (aCGH) on which it was originally developed. We investigated samples from 230 breast cancer patients for which a CN profile had been generated on two to five platforms, comprising low coverage CN sequencing, CN extraction from targeted sequencing panels (CopywriteR), Affymetrix SNP6.0, 135K/720K oligonucleotide aCGH, Affymetrix Oncoscan FFPE (MIP) technology, 3K BAC and 32K BAC aCGH. Pairwise comparison of genomic position-mapped profiles from the original aCGH platform and other platforms revealed concordance. For most cases, biological differences between samples exceeded the differences between platforms within one sample. We observed the same classification across different platforms in over 80% of the patients and kappa values of at least 0.36. Differential classification could be attributed to CN profiles that were not strongly associated to one class. In conclusion, we have shown that the genomic regions that define our BRCA1-like classifier are robustly measured by different CN profiling technologies, providing the possibility to retro- and prospectively investigate BRCA1-like classification across a wide range of CN platforms.","BRCA1; breast cancer; classification; copy number aberration profiles","en","journal article","Elsevier","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Intelligent Systems","","","",""
"uuid:25aa3426-a741-4f2d-81d4-f55aefbe7214","http://resolver.tudelft.nl/uuid:25aa3426-a741-4f2d-81d4-f55aefbe7214","CE Challenges: Work to Do","Stjepandic, J (PROSTEP AG); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Wognum, Nel (TU Delft Air Transport & Operations)","","2015","style=""margin: 0cm 0cm 10pt;"">CE has been used for more than two decades now. Despite many successes and advantages, there are still many challenges to be addressed. These challenges are both technical and organisational. In the paper we will address the current challenges of CE. Many challenges are related to the exchange of data and knowledge and to the systems that make data and knowledge exchange possible. Although much progress has been made in enabling extensive data and knowledge exchange and use, much remains to be wished. For example, there are still barriers to data exchange. Technically, these barriers may consist of different formats, differences in infrastructures and systems, and different semantics. There are also organisational and political barriers. For example, investment in information system may heavily impact upstream suppliers, while revenues of better information exchange may predominantly be gained by downstream actors. Without sharing costs and revenues, chain-wide information exchange will not be easily realised. Another barrier is the possible lack of willingness to share information, because of potential misuse of knowledge and loss of power. The paper is organised as follows. First we will describe the current manifestation of CE as described in a recent book. Second, we will list current trends in CE. Third, we will present some Critical Success Factors (CSFs) that are considered relevant for implementing and adapting CE practices. Last, we indicate some research and practical questions to be addressed, especially for areas that have a high potential and actual impact.","Cross-disciplinary; cross-functional; cross-boundary collaboration; information and knowledge exchange","en","conference paper","IOS Press","","","","","","","","","","Air Transport & Operations","","",""
"uuid:c24e2938-19a1-4cb0-a7a8-6683175b1817","http://resolver.tudelft.nl/uuid:c24e2938-19a1-4cb0-a7a8-6683175b1817","Tony's Chocolonely","Blom, E.M.; Burg, E.; Verhagen, P.; Hillen, M.","","2014","","","en","conference paper","Stichting Social Enterprise NL","","","","","","","","Technology, Policy and Management","Values, Technology and Innovation","","","",""
"uuid:8f08711e-c82d-41c1-95f9-b406704244ae","http://resolver.tudelft.nl/uuid:8f08711e-c82d-41c1-95f9-b406704244ae","Wave overtopping simulator tests on Vietnamese sea dikes","Trung, L.H.; Van der Meer, J.W.; Verhagen, H.J.","","2014","Little is known about the strength of the land-side slopes of the Vietnamese sea dikes under overtopping attack. Some grass-covered slopes were tested by a wave overtopping simulator. The paper describes the simulator and presents the test results. The tested grass covers could withstand overtopping rates varying from 20 l/s to 100 l/s per meter of dike length in some hours. Damage usually started at bare spots, at the transition between the slope and the toe, at the transition between different materials, and around objects (e.g. big trees). These features reduce the strength of a grass cover and therefore should be avoided.","grass cover; wave overtopping; simulator; sea dikes","en","journal article","World Scientific","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:7ba61dc3-5714-40f2-bee7-37b7941497a2","http://resolver.tudelft.nl/uuid:7ba61dc3-5714-40f2-bee7-37b7941497a2","The use of polyurethane in coastal engineering models","Verhagen, H.J.","","2014","In physical model tests there is often a need of preventing stones from moving. This can be achieved by gluing the stones. Applying PBA (Polyurethane Bonded Agregate, e.g. Elastocoast) guarantees no moving stones, a normal permeability and a transportable model.","hydraulic model test; scale model; physical model tests; epoxy resin; polyurethane glue; PBA; Polyurethane bonded material","en","conference paper","Black Sea - Danube Coastal Research Association (BDCA)","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:56fec991-2026-49e7-b0cb-1faeea36d55a","http://resolver.tudelft.nl/uuid:56fec991-2026-49e7-b0cb-1faeea36d55a","Damage to Grass Covered Slopes Due to Overtopping","Hai, T.L.; Verhagen, H.J.","","2014","Many dike failures have been ignited by damage due to erosion on the landward slopes. This paper investigates how grass covered slopes perform when being attacked by overtopping flow during storm surges. Based on observations during a number of simulator tests, damage is classified into three types 'head-cut', 'roll-up' and 'collapse' depending on the combination of grass, material components and corresponding layer thickness. To quantitatively predict the potential types, strength ratio and thickness ratio are proposed. Besides, erosion usually starts at weak spots so their spatial distributions are evaluated along dike stretches with various lengths. Finally, the overtopping resistance of a grass turf is presumably represented by critical velocities depending on soil cohesion and apparent cohesion induced by roots. The computed results are comparable to erosion on Bermuda and Carpet grass slopes tested with the simulator.","slope; grass; overtopping; revetment; damage; ICCE 2014","en","conference paper","Coastal Engineering Research Council","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:97f11a22-56ad-4504-a42a-cfedcb3677ca","http://resolver.tudelft.nl/uuid:97f11a22-56ad-4504-a42a-cfedcb3677ca","Towards a Practical Application of Numerical Models to Predict Wave-Structure Interaction: An Initial Validation","Van den Bos, J.; Verhagen, H.J.; Zijlema, M.; Mellink, B.","","2014","A more detailed understanding of porous flow inside a rubble-mound structure may have potential benefits in breakwater design. Numerical models are expected to be a useful additional research tool in this field, provided that their calculation results can be validated against measurements. This paper presents the results of a systematic effort to validate a set of different numerical models for a strongly simplified model set-up. The results of this effort will be used to select models for a next stage in which the complexity of the model set-up is increased. By means of this step-by-step approach a good insight in the capabilities and limitations of the various models is achieved.","rubble-mound structures; porous flow; numerical modelling; VOF modelling; breakwaters; ICCE 2014","en","conference paper","Coastal Engineering Research Council","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:a7933cdb-8788-4462-9694-32f142062f64","http://resolver.tudelft.nl/uuid:a7933cdb-8788-4462-9694-32f142062f64","The Use of Mangroves in Coastal Protection","Tusinski, A.; Verhagen, H.J.","","2014","The objective of this research is to obtain generic relations between attenuated wave heights and various vegetation and topographical scenarios. Subsequently, it is aimed to find out what is the actual cost profit of a dike construction behind a mangrove zone comparing to the case when mangroves are absent. The graphs and formulas developed in this research may serve as a first approximation during feasibility studies or conceptual designs of a coastal dike incorporating mangrove vegetation. They allow calculating the design wave height attenuated by site specific or planned for restoration mangrove forests, for different design met-ocean conditions. Calculated wave reduction coefficients can be later on translated to the cost savings of a coastal dike raised behind the mangrove forests.","mangroves; coastal dikes; cost; coastal protection; ICCE 2014","en","conference paper","Coastal Engineering Research Council","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:104c70bb-4abb-4134-807d-776466d052ad","http://resolver.tudelft.nl/uuid:104c70bb-4abb-4134-807d-776466d052ad","Atherosclerotic Plaque Component Segmentation in Combined Carotid MRI and CTA Data Incorporating Class Label Uncertainty","Van Engelen, A.; Niessen, W.J.; Klein, S.; Groen, H.C.; Verhagen, H.J.M.; Wentzel, J.J.; Van der Lugt, A.; De Bruijne, M.","","2014","Atherosclerotic plaque composition can indicate plaque vulnerability. We segment atherosclerotic plaque components from the carotid artery on a combination of in vivo MRI and CT-angiography (CTA) data using supervised voxelwise classification. In contrast to previous studies the ground truth for training is directly obtained from 3D registration with histology for fibrous and lipid-rich necrotic tissue, and with CT for calcification. This registration does, however, not provide accurate voxelwise correspondence. We therefore evaluate three approaches that incorporate uncertainty in the ground truth used for training: I) soft labels are created by Gaussian blurring of the original binary histology segmentations to reduce weights at the boundaries between components, and are weighted by the estimated registration accuracy of the histology and in vivo imaging data (measured by overlap), II) samples are weighted by the local contour distance of the lumen and outer wall between histology and in vivo data, and III) 10% of each class is rejected by Gaussian outlier rejection. Classification was evaluated on the relative volumes (% of tissue type in the vessel wall) for calcified, fibrous and lipid-rich necrotic tissue, using linear discriminant (LDC) and support vector machine (SVM) classification. In addition, the combination of MRI and CTA data was compared to using only one imaging modality. Best results were obtained by LDC and outlier rejection: the volume error per vessel was 0.91.0% for calcification, 12.77.6% for fibrous and 12.18.1% for necrotic tissue, with Spearman rank correlation coefficients of 0.91 (calcification), 0.80 (fibrous) and 0.81 (necrotic). While segmentation using only MRI features yielded low accuracy for calcification, and segmentation using only CTA features yielded low accuracy for necrotic tissue, the combination of features from MRI and CTA gave good results for all studied components.","","en","journal article","Public Library of Science","","","","","","","","Applied Sciences","ImPhys/Imaging Physics","","","",""
"uuid:fca21e50-98a7-43b7-b5b0-5a863bb4b833","http://resolver.tudelft.nl/uuid:fca21e50-98a7-43b7-b5b0-5a863bb4b833","Fifteen years of international space station","Verhagen, B.; Celebi, T.","","2014","The International Space Station (ISS) celebrated its 15th birthday in October 2013. The ISS is the largest spaceship ever built by humans and very important for research, to understand life and physics. However, the ISS is very expensive to maintain and therefore some people argue that the ISS program should stop. The US president has decided to support the extension of the operations of the ISS to at least 2020.","","en","journal article","Society for Aerospace Engineering Students VSV Leonardo da Vinci","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f3204674-3a72-4515-92f5-92a8f91d8a15","http://resolver.tudelft.nl/uuid:f3204674-3a72-4515-92f5-92a8f91d8a15","Ratio between stone diameter and nominal diameter","Verhagen, H.J.; Jansen, L.","","2014","For describing the relation between the grainsize and the nominal diameter (d50 vs. dn50) usually a factor 0.84 is used. This factor has been derived by Laan [1981] ""De relatie tussen vorm en gewicht van breuksteen (the relation between shape and weight of pieces of rock), report MAW-R-81079"". However, this original report cannot be retrieved any more. This study has collected new data to re-establish the background of the used factor 0.84.","rock diameter; rock size; nominal diameter","en","report","TU Delft, Department Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:adf3122e-503b-485d-83bf-64d2611c4845","http://resolver.tudelft.nl/uuid:adf3122e-503b-485d-83bf-64d2611c4845","GNSS integer ambiguity estimation and evaluation: LAMBDA and Ps-LAMBDA","Li, B.; Verhagen, A.A.; Teunissen, P.J.G.","","2013","Successful integer carrier-phase ambiguity resolution is crucial for high precision GNSS applications. It includes both integer estimation and evaluation. For integer estimation, the LAMBDA method has been applied in a wide variety of GNSS applications. The method’s popularity stems from its numerical efficien-cy and statistical optimality. However, before conducting ambiguity resolution, one needs to infer how reliable the fixed solution can expected to be, as incorrect fixed ambiguity solutions often lead to unacceptable positioning errors. In this pa-per, two Matlab software tools are introduced for the evaluation and integer esti-mation: Ps-LAMBDA and an updated version of LAMBDA. Evaluation of the in-teger solution is based on the ambiguity success rate. Since this probability of correct integer estimation is generally difficult to compute, easy-to-use approxi-mations and bounds of the ambiguity success rate are provided by the Ps-LAMBDA software. This success rate tool is valuable not only for inferring whether to fix the ambiguities but also for design and research purposes. For the actual integer estimation, the updated version of the LAMBDA software, provides now more options of integer estimation and integer search, including the search-and-shrink strategy. In addition, the Fixed Failure-rate Ratio Test (FF-RT) and the Fixed Critical-value Ratio Test (FC-RT) are incorporated for users to validate the significance of the fixed solution. Using these two software tools together allows for the combined execution of integer estimation and evaluation, thus benefiting multi-frequency, multi-GNSS applications.","LAMBDA; Ps-LAMBDA; integer rounding; integer bootstrapping; integer least-squares; search-and-shrink; ambiguity success rate; ambiguity resolution","en","conference paper","Springer","","","","","","","","Civil Engineering and Geosciences","Geoscience & Remote Sensing","","","",""
"uuid:4467a9c3-edee-4822-b420-1c4286b717d3","http://resolver.tudelft.nl/uuid:4467a9c3-edee-4822-b420-1c4286b717d3","The uses of norms","Singh, M.P.; Arrott, M.; Balke, T.; Chopra, A.; Christiaanse, R.M.J.; Cranefield, S.; Dignum, F.; Eynard, D.; Farcas, E.; Fornare, N.; Gandon, F.; Governatori, G.; Dam, H.K.; Hulstijn, J.; Krueger, I.; Lam, H.P.; Meisinger, M.; Noriega, P.; Tony, B.; Savarimuthu, R.; Tadanki, K.; Verhagen, H.; Villata, S.","","2013","This chapter presents a variety of applications of norms. These applications include governance in sociotechnical systems, data licensing and data collection, understanding software development teams, requirements engineering, assurance, natural resource allocation, wireless grids, autonomous vehicles, serious games, and virtual worlds.","norms; MAS; governance; requirements engineering","en","book chapter","Dagstuhl","","","","","","","","Technology, Policy and Management","Infrastructures, Systems and Services","","","",""
"uuid:6ae1ba54-0e3a-4398-9a08-69ce112d7789","http://resolver.tudelft.nl/uuid:6ae1ba54-0e3a-4398-9a08-69ce112d7789","How space syntax can be applied in regenerating urban areas: Applying macro and micro spatial analyses in strategic improvements of 8 Dutch neighbourhoods","Van Nes, A.; Lopez, M.; De Bonth, L.; Verhagen, D.; Waayer, S.","","2013","","space syntax in urban regeneration; network configuration; crime; communicative planning","en","conference paper","Sejong University Press","","","","","","","","Architecture and The Built Environment","Urbanism","","","",""
"uuid:d748761c-14b9-4c5c-8bd8-0f94d13c0f83","http://resolver.tudelft.nl/uuid:d748761c-14b9-4c5c-8bd8-0f94d13c0f83","Predictive control of thermally induced wavefront aberrations","Haber, A.; Polo, A.; Maj, I.; Pereira, S.F.; Urbach, H.P.; Verhagen, M.H.G.","","2013","In this paper we experimentally demonstrate the proof of concept for predictive control of thermally induced wavefront aberrations in optical systems. On the basis of the model of thermally induced wavefront aberrations and using only past wavefront measurements, the proposed adaptive optics controller is able to predict and to compensate the future aberrations. Furthermore, the proposed controller is able to correct wavefront aberrations even when some parameters of the prediction model are unknown. The proposed control strategy can be used in high power optical systems, such as optical lithography machines, where the predictive correction of thermally induced wavefront aberrations is a crucial issue.","","en","journal article","Optical Society of America","","","","","","","","Mechanical, Maritime and Materials Engineering","Delft Center for Systems and Control","","","",""
"uuid:5ce23847-53ac-4fb4-b3e5-72c04fdc4512","http://resolver.tudelft.nl/uuid:5ce23847-53ac-4fb4-b3e5-72c04fdc4512","Effect of uncertainty in wave growth calculation on overtopping over dikes: A case study","Verhagen, H.J.","","2013","Example calculation of a dike height incorporating the uncertainty in the wave growth formula of Young and Verhagen.","wave growth; overtopping; dike height","en","report","TU Delft, Department of Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:73e1f001-2616-47ba-9e83-83a386009d73","http://resolver.tudelft.nl/uuid:73e1f001-2616-47ba-9e83-83a386009d73","An Ontology-Based Approach for Knowledge Lifecycle Management within Aircraft Lifecycle Phases","Verhagen, W.J.C.","Curran, R. (promotor)","2013","In the aerospace domain, manufacturers and operators constantly seek to improve their products and processes. Increasingly, knowledge-based applications are developed to support or automate knowledge-intensive engineering tasks, saving time and money. However, engineering knowledge changes over time, which has implications for the usability and maintainability of knowledge-based applications. The research presented in this thesis contributes to the development of theory regarding knowledge change in engineering tasks. A conceptual knowledge lifecycle model to characterise and quantify knowledge change is presented. Additionally, this thesis proposes a methodology and an ontology-based approach to support the development of robust knowledge-based applications that can cope with knowledge change. These research contributions are validated in three case studies that consider engineering tasks in the aircraft design, manufacturing and maintenance lifecycle phases. The case studies demonstrate the utility of knowledge lifeycle management as usability and maintainability of knowledge-based applications are improved.","knowledge; knowledge change; knowledge-based applications; KBE; aircraft engineering; knowledge management; knowledge lifecycle; ontology","en","doctoral thesis","BOXPress","","","","","","","2013-07-18","Aerospace Engineering","Air Transport & Operations","","","",""
"uuid:7cf8c9e7-d525-48ed-83cb-ef01368e6279","http://resolver.tudelft.nl/uuid:7cf8c9e7-d525-48ed-83cb-ef01368e6279","EMS wave logger data processing","Verhagen, H.J.","","2013","Waves can be measured in several ways. One way of measuring waves is by measuring the wave pressure at a certain depth using a pressure sensor and calculate the wave information from the pressure record. The EMS wave logger uses a Honeywell MLH 050 PGP 06A pressure sensor. The information is stored by the logger on a SD card. The software in the logger controls the sample durations (from 1 to 30 minutes) and the sample intervals (from 15 min to 3 hours). The sampling rate is fixed to 4 Hz. In this report software is presented to evaluate the data from the wavelogger","pressure sensor; wave measurements; water level measurements; wave sprectrum","en","report","TU Delft, Department Hydraulic Engineering","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:78f95de4-7505-4a68-8cb1-07098856d1f8","http://resolver.tudelft.nl/uuid:78f95de4-7505-4a68-8cb1-07098856d1f8","Analysis of the carbon footprint of coastal protection systems","Labrujere, A.L.; Verhagen, H.J.","","2012","When calculating the Carbon Footprint for a product or service, a direct link is made between the total amount of consumed energy and the produced amount of carbon dioxide during production. For that reason calculating the carbon footprint of various alternatives is a very straightforward method to compare energy consumption and more importantly environmental pollution. Applying this method to large hydraulic engineering projects is not being done frequently. In this study the possibilities to apply the Carbon Footprint method to coastal protection systems have been explored and analyzed. The analyses are based on a case study: A reinforcement work at the Dutch coast","carbon footprint, coastal protection, carbon dioxide, energy","en","conference paper","Coastal Engineering Research Council","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:74b2d97e-1ccf-412f-a545-6183bc58e9a1","http://resolver.tudelft.nl/uuid:74b2d97e-1ccf-412f-a545-6183bc58e9a1","Air Transport and Operations. Proceedings of the Third International Air Transport and Operations Symposium 2012","Curran, R.; Fischer, L.; Pérez, D.; Klein, K.; Hoekstra, J.; Roling, P.; Verhagen, W.J.C.","","2012","Air transport must evolve if it is to optimize its value in the 21st century. The mood in the aerospace industry is positive with regard to economic recovery, but the focus in this transitional time must be on sustaining value, without losing sight of environmental and safety priorities","","en","book","IOS Press","","","","","","","","Aerospace Engineering","","","","",""
"uuid:707054e4-b314-49e1-bfd8-abe7d4a067cb","http://resolver.tudelft.nl/uuid:707054e4-b314-49e1-bfd8-abe7d4a067cb","The application of a tandem dike system in Vietnam","Tri, M.C.; Cong, M.V.; Verhagen, H.J.; Nghia, N.K.","","2012","In the low-lying coastal regions coastal defense structures are usually designed with a main function to protect the hinterland from highly vulnerable of sea flooding. Sea dikes are usually the most common and important elements which form the coastal flood defense system. Sea dikes are designed at a pre-defined circumstance and requirement. For instance, dikes are designed where no overtopping, some overtopping or large overtopping water is allowed. The most interesting issues at the preliminary design stages of a sea dike are its height, layout and associated overtopping discharge criteria. There have been many discussions on whether sea dikes should be designed high enough to not allow any overtopping water or using relatively low but “strong” dikes in order to allow from some to large overtopping water. Recently, the ComCoast1 project develops and demonstrates innovative solutions for flood protection in coastal areas. In which different types of dike cross section and layouts of defensive system were proposed. Concepts of defensive zones are presented beside the already existing concept of defensive lines. However, within the ComCoast project, attentions are paid mainly to developments of the innovated concepts rather than focusing on comparison of the proposed system with the conventional sea defenses. Thus, there is still lack of guidance and comparative tools to determine the best choice amongst the conventional or innovated options in decision making process. This study focuses on development of the comparative framework and generic guidance to support the decision making process in selection of the best suitable layout option of the sea dike system for a given location. Based on overtopping criteria two situations are considered for the analysis: (i) using one defensive line; (ii) using two defensive lines (defense zone). The multi-criteria analysis (which takes social, economic, environment and technical aspects into account) and the cost-benefit analysis are used in the selection of the best option. Finally application is made for several case studies of coastal flood defense in Vietnam.","sea dike; tandem dike; flood defense system","en","conference paper","Water Resources University","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:5a7f56eb-d7e2-49ea-b638-a2ebc47d414f","http://resolver.tudelft.nl/uuid:5a7f56eb-d7e2-49ea-b638-a2ebc47d414f","Static and dynamic loads on the bottom row of armour units: A theoretical and physical model study","Van de Koppel, M.A.; Muilwijk, M.; Verhagen, H.J.","","2012","A physical model study on the row averaged static and dynamic load on the bottom row of single layer armour units in order to investigate the influence of various parameters such as the number of rows on the slope of a breakwater and the initial relative packing density.","rubble-mound breakwater; static load; dynamic load; bottom row","en","conference paper","Coastal Engineering Research Council","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:8fcdd179-3761-45dc-af70-ed2bbf7c3be4","http://resolver.tudelft.nl/uuid:8fcdd179-3761-45dc-af70-ed2bbf7c3be4","Spatial distribution of overtopping","Lioutas, A.; Smith, G.M.; Verhagen, H.J.","","2012","The scope of this research is to find an empirical formula to describe the distribution of wave overtopping in the region behind the crest. A physical model was set up in which irregular waves were generated. In order to find a formula which adequately describes the test observations, the influence of several parameters has been analysed. The proper determination of the crest freeboard, which is a dominant factor, has been investigated. Finally, the test results have been used to assess and compare the existing relevant computational methods.","overtopping; rubble-mound breakwater; physical modelling; spatial distribution; crest freeboard","en","conference paper","Coastal Engineering Research Council","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:9db07aae-8a56-4957-9ceb-d8b58aeddea5","http://resolver.tudelft.nl/uuid:9db07aae-8a56-4957-9ceb-d8b58aeddea5","Notional Permeability","Kik, R.; Van den Bos, J.P.; Maertens, J.; Verhagen, H.J.; Van der Meer, J.W.","","2012","Different layer design of a rock slope and under layers has a large effect on the strengths on the rock slope itself. In the stability formula developed of VAN DER MEER [1988] this effect is represented by the term Notional Permeability with symbol P. A more open, or permeable, structure underneath the armour layer has the ability to dissipate more wave energy and therefore requires less weight of the armour layer. The influence of this parameter is thus very important in economic sense. Up until now only three configurations have been tested. In practice often intermediate structures were designed which do not correspond to the standard situations. P-values then have to be estimated in comparison with the known structures, which gives some uncertainty around the P-value. Therefore there is the demand for more validated values of the notional permeability representing other structures. During this study physical scale modelling is used to produce a value of P for a new structure.","rubble-mound breakwater; notional permeability; van der Meer","en","conference paper","Coastal Engineering Research Council","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:bd5e6a16-d8f1-494a-b765-4fc4e8a984ed","http://resolver.tudelft.nl/uuid:bd5e6a16-d8f1-494a-b765-4fc4e8a984ed","Hydrodynamic load on the building caused by overtopping waves","Chen, X.; Hassan, W.; Uijttewaal, W.; Verwaest, T.; Verhagen, H.J.; Suzuki, T.; Jonkman, S.N.","","2012","Wide crested dike can reduce the kinetic energy of the overtopping wave and make the overtopping wave to flow back to the seaside. If a coastal town were built on or near a dike, the overtopping wave running on the dike crest generates the force which can affect the buildings located in its path. However, quantifying the hydrodynamic load on the building caused by overtopping waves is not straightforward because little empirical formulas are given in literature for this kind of configuration. Therefore, physical scale model research was carried out. The purpose of this research is to come up with a relationship describing the force on a vertical wall exerted by the overtopping wave as a function of wave parameters and geometrical characteristics.","overtopping wave; hydrodynamic load; vertical wall; wide crested dike","en","conference paper","Coastal Engineering Research Council","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:31b0bbc0-6464-4797-84cc-192992fa1487","http://resolver.tudelft.nl/uuid:31b0bbc0-6464-4797-84cc-192992fa1487","Breakwaters under construction exposed to oblique waves","Mulders, P.H.M.; Verhagen, H.J.","","2012","A new series of physical model tests were conducted to analyse the behaviour of a breakwater core when it becomes exposed to wave attack. The emphasis of this research was on the measured influence of a wide stone grading on both the deformation of a breakwater trunk and the occurring longshore transport. This behaviour was investigated for both head-on and oblique waves using two different wave loads. The findings were compared to the currently available formulas and the validity of these formulas for the tested range of parameters was (re)checked. In general a clear distinction was found in the processes between tests with narrow grading and wide grading. It turned out that both the parameters describing the two-dimensional deformation and the longshore transport show an increase for wider grading.","rubble-mound breakwater; core; grading; physical model test; two-dimensional deformation; stone displacement; longshore transport","en","conference paper","Coastal Engineering Research Council","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:34061631-a588-4029-847a-6479f0d8a9e4","http://resolver.tudelft.nl/uuid:34061631-a588-4029-847a-6479f0d8a9e4","Evanescent states and nonequilibrium in driven superconducting nanowires","Vercruyssen, N.; Verhagen, T.G.A.; Flokstra, M.G.; Pekola, J.P.; Klapwijk, T.M.","","2012","We study the nonlinear response of current transport in a superconducting diffusive nanowire between normal reservoirs. We demonstrate theoretically and experimentally the existence of two different superconducting states appearing when the wire is driven out of equilibrium by an applied bias, called the global and bimodal superconducting states. The different states are identified by using two-probe measurements of the wire, and measurements of the local density of states with tunneling probes. The analysis is performed within the framework of the quasiclassical kinetic equations for diffusive superconductors.","","en","journal article","American Physical Society","","","","","","","","Applied Sciences","QN/Quantum Nanoscience","","","",""
"uuid:84541e27-6382-4cb2-ae35-c5365aa7be90","http://resolver.tudelft.nl/uuid:84541e27-6382-4cb2-ae35-c5365aa7be90","Stability of pattern placed revetment elements","Dorst, K.; Provoost, Y.; Verhagen, H.J.","","2012","A revetment of pattern placed elements, or a so called pitching, is used worldwide to protect shorelines and embankments. Also in The Netherlands more than 500 km of river, lake and sea dikes is protected by pitchings. Until the 60’s the design and construction of pitchings was based on experience. After the first damages on pitchings and the negative assessment results, an intensive investigation program on pitchings was carried out. The results are commonly used nowadays in the Dutch dike reinforcement works. When comparing pattern placed block revetments with other revetments, the remarkable difference is that the amount of material to be used is significantly less than when using loose riprap. However placing blocks is more labour intensive. This is a specific advantage for countries with a large inexpensive labour force. In China, Vietnam and Bangladesh these are very common constructions. The leakage length L, describing the relationship between top layer elements and sublayer properties, is the most important design parameter; a small leakage length is favourable for the stability of the pitching. The maritime commission of PIANC has in 2007 decided to start a working group to make a small document on the design of pattern placed revetment elements. This PIANC MARCOM working group 57 report is now available (PIANC report 114, 2011). This paper presents an outline of this new knowledge of pattern placed block revetments, required for assessment and design purposes usable all over the world. It follows more or less the contents of the new PIANC report.","pitching; pattern placed; concrete blocks; revetment","en","conference paper","PIANC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:85a6189f-89e9-4618-abb7-db47cc13e2a7","http://resolver.tudelft.nl/uuid:85a6189f-89e9-4618-abb7-db47cc13e2a7","The use of mangroves in coastal protection","Verhagen, H.J.","Loi, T.T. (contributor)","2012","Apart from many ecological advantages, mangroves in front of a coastal defence may lower the construction and maintenance costs of the defence. Although mangroves have hardly any reducing effect on water levels (and on tsunami impact) mangroves may significantly reduce wave attack on a coastal dike, and in this way reduce the cost of a revetment and lower the design height of a levee because of reduced run]up and overtopping height. This paper describes a design tool for the required width of the mangrove belt, as well as some guidance for planting the mangroves. Design graphs are presented to determine the required mangrove belt as a function of deep water wave action and mangrove density.","mangroves; coastal protection; sea dikes; revetment","en","conference paper","PIANC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:c724be88-cee4-48d7-9323-dd5f77d5af72","http://resolver.tudelft.nl/uuid:c724be88-cee4-48d7-9323-dd5f77d5af72","Wave overtopping reduction by seadike crown-walls in Vietnam","Tuan, T.Q.; Verhagen, H.J.","","2012","Extensive laboratory experiments were carried out to investigate wave overtopping on seadikes with (vertical) crown-walls in Vietnam. It is shown that the wave overtopping reduction by walls is inadequately, although rather complexly, described by TAW-2002. A new approach has been developed, which can straightforwardly be incorporated in the original formulations of TAW-2002 to improve the prediction of wave overtopping on sea-dikes crowned with this type of walls.","wave overtopping; seadike; crown-wall; promenade; overtopping reduction","en","conference paper","PIANC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:d52dd3ea-f4ec-4ab9-9a22-af29aca63d38","http://resolver.tudelft.nl/uuid:d52dd3ea-f4ec-4ab9-9a22-af29aca63d38","Strength of the landward slopes of sea dikes in Vietnam","Trung, L.H.; Verhagen, H.J.; Van der Meer, J.W.; Cat, V.M.","","2012","The landware slopes of sea dikes in the north of Vietnam are steep and solely constructed by soil covered with grass due to the budget constraints and also the out-of-date design guidelines.The resistance against erosion due to wave overtopping of several grass covered slopes were tested with the Wave Overtopping Simulator to show if a slope covered with grass could withstand a certain amount of overtopping. An analysis of all test results obtained in the Netherlands and Viet Nam is made as an attempt to establish a reference for empirically assessing the strength of grass covers. Slope classification should be based on its specifications whether it is a plain slope or a slope with existing damages and obstacles.","grass covered slope; landward slope; overtopping; sea dike; simulator","en","conference paper","PIANC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:62444c4e-650b-41b2-ac23-d9fc8a543a2b","http://resolver.tudelft.nl/uuid:62444c4e-650b-41b2-ac23-d9fc8a543a2b","A tool for GNSS integrity verification based on statistical extreme value theory","Veerman, H.; Van Kleef, A.; Wokke, F.; Ober, O.; Tiberius, C.C.J.M.; Verhagen, A.A.; Bos, A.; Mieremet, A.","","2012","The paper presents a short introduction to the mathematical theory of the EVT, the consecutive steps that are made in the software tool to address MI probability estimation and proof of range error distribution overbounding. Finally some early results obtained by GIMAT are presented.","","en","conference paper","Institute of Navigation","","","","","","","","Civil Engineering and Geosciences","Geoscience & Remote Sensing","","","",""
"uuid:759acf83-3aa9-47f7-8458-546d588dc344","http://resolver.tudelft.nl/uuid:759acf83-3aa9-47f7-8458-546d588dc344","Probabilistic design of breakwaters in shallow hurricane-prone areas","Tsimopoulou, V.; Kanning, W.; Voortman, H.G.; Verhagen, H.J.","","2011","One of the failure mechanisms of a rubble mound breakwater is the failure of its armour layer. In order to determine the stability of an armour layer, the design load has to be defined, which is in fact the wave that attacks the structure. Being a highly stochastic phenomenon, the wave action is not easily defined, while there is always some uncertainty inherent to its definition. In a deterministic calculation this uncertainty is being left to engineering judgment, as the possible variations of the design wave height are not taken into account in a coherent way. In order to explicitly incorporate uncertainties into the design process, and therefore increase its reliability, probabilistic design methods should be applied. A commonly used approach is a semi-probabilistic computation, which introduces the application of partial safety coefficients. Nevertheless the indicated methods to derive and apply them do not clarify the uncertainties incorporated, adding an undefined degree of safety in the process, or end up with incorrect results under certain conditions. Another approach is a fully probabilistic computation. This type of design tackles explicitly a great deal of uncertainties, hence its results can be considered much more accurate. However it is not commonly used, due to the fact that there are not straightforward guidelines to support it, and therefore a number of critical decisions by the designers are required. This paper focuses on the application of probabilistic methods for armour layer design of rubble mound breakwaters. The main objective is to indicate the weaknesses of the previously mentioned methods, and to suggest a probabilistic design approach that is both attractive to designers and sufficiently reliable. This can be achieved through elaboration of a design example with the various methods, followed by a critical evaluation of the results.","","en","conference paper","Institute of Civil Engineers","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:09212a59-23bb-42c6-9a13-9459506959ab","http://resolver.tudelft.nl/uuid:09212a59-23bb-42c6-9a13-9459506959ab","Capacity building and training for ICZM","Marchand, M.; Thu, H.T.Y.; Verhagen, H.J.","","2011","","","","book chapter","Coastal and Marine Union EUCC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:075deb5b-5253-4daf-97be-f7126519612b","http://resolver.tudelft.nl/uuid:075deb5b-5253-4daf-97be-f7126519612b","GNSS ambiguity resolution: Which subset to fix?","Verhagen, A.A.; Teunissen, P.J.G.; Van der Marel, H.; Li, B.","","2011","A key issue with GNSS carrier phase ambiguity resolution is that often the full set of ambiguities cannot be fixed fast and reliably. A possible strategy is then to resolve only a subset of ambiguities, one for which the probability of correct fixing, the so-called success rate, is sufficiently close to 1. However, a proper subset selection criterion is still lacking. This criterion should on the one hand guarantee an acceptably high success rate, and at the same time result in a significant performance improvement with respect to the remaining parameters, like the baseline parameters. The second requirement is important and has not yet been addressed in literature. As an extreme example consider the case where the float ambiguities are not correlated with the other float parameters. Ambiguity resolution would then be useless, since it will then not allow for an improvement of these other parameters. This indicates that resolving a subset of ambiguities (in the extreme example, an empty subset) may lead to the same, or almost same, performance improvement of the other parameters, notably the baseline solution. This contribution presents two approaches to subset selection, where both the requirements on success rate and performance improvement are taken into account. With this approach the user can set a threshold for the success rate to be obtained. It will be shown how much better the baseline solution will be after reliable fixing of the subset of ambiguities.","partial ambiguity resolution; success rate; precision and reliability","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Geoscience & Remote Sensing","","","",""
"uuid:664583ca-9dea-45f6-9abe-ae49e49adb33","http://resolver.tudelft.nl/uuid:664583ca-9dea-45f6-9abe-ae49e49adb33","Training of coastal engineers to work in a non-engineering environment","Burgmeijer, M.A.; Verhagen, H.J.; Van der Wegen, M.","","2011","Integrated Coastal Zone Management (ICZM) is an interdisciplinary process by definition. Individual actors in CZM need to cooperate and communicate to come to an optimum management strategy for the coastal zone. Because engineers focus on finding the “best” solution in engineering terms, they often are quite surprised that in the end of the day their best solution is not considered as the best solution by the other participants in the process. At Delft University and UNESCO-IHE we started in 1990 with a course on ICZM, which evolved into a training course for engineers to make them aware of this point and to train them in communication with other professionals [Verhagen, 1995]. This paper will give an overview of the experience with this course gained over the last 20 years.","coastal zone management; training","en","conference paper","Thomas Telford","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:d4ac96e7-194a-4a3a-aa9c-ce8364ca3073","http://resolver.tudelft.nl/uuid:d4ac96e7-194a-4a3a-aa9c-ce8364ca3073","Wave overtopping resistance of grassed slopes in Viet Nam","Trung, L.H.; Verhagen, H.J.; Van der Meer, J.W.","","2011","The Simulator was applied to test the resistance against wave overtopping of grass covered dike slopes in Viet Nam. Observation and measurement during destructive tests were performed to investigate the development process of damage induced by overtopping flow. Damages were likely to be initiated at transition of either geometry or materials, at eroded holes and around objects existing on the slope. Grass cover could withstand a certain overtopping rate that varies widely and in order of 10 l/s per m.","wave overtopping; grass slope; damage; erosion; transition; grass root","en","conference paper","RWTH-Aachen","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:02fb15b6-5742-4fc7-a5b4-41233cf500ad","http://resolver.tudelft.nl/uuid:02fb15b6-5742-4fc7-a5b4-41233cf500ad","Rationalization of safety factors for breakwater design in hurricane-prone areas","Tsimopoulou, V.; Kanning, W.; Verhagen, H.J.; Vrijling, J.K.","","2011","This paper presents the development of a semi-probabilistic method for armour layer design of rubble mound breakwaters, which is based on the use of safety factors. The objective is to introduce an approach that is both attractive to designers and sufficiently reliable when a high degree of uncertainty is involved in the design process. The main focus of the analysis is the calibration and appropriate use of the safety factors, which is the key element for a reliable result.","","en","conference paper","American Society of Civil Engineers (ASCE)","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:53e267d9-d6e7-47c4-a479-57b48d60c51d","http://resolver.tudelft.nl/uuid:53e267d9-d6e7-47c4-a479-57b48d60c51d","Wave overtopping resistance of grassed dike slopes in Vietnam","Trung, L.H.; Van der Meer, J.W.; Luong, N.Q.; Verhagen, H.J.; Schiereck, G.J.","","2011","The resistance of various grassed slopes against wave overtopping has been appraised by means of the Wave Overtopping Simulator in situ for a couple of years in Viet Nam. Destructive test results show that a dike slope covered with grass could suffer a certain overtopping discharge not smaller than 20 l/s per m. During testing it was difficult to predict when a slope starts to be damaged, however, damages tend to follow a more or less similar process of development. The concept of “erosional indices” and the method of “cumulative overload” (van der Meer et al., 2010) are applied to the simulator tests in Viet Nam. Critical velocities were then estimated for different kind of grassed slopes.","Bermuda grass; dike; grass slope; erosion; vetiver grass; wave overtopping; wave overtopping simulator","en","conference paper","American Society of Civil Engineers (ASCE)","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:d0136d40-192d-4900-8e1e-27f292b7f095","http://resolver.tudelft.nl/uuid:d0136d40-192d-4900-8e1e-27f292b7f095","Method to quantify the notional permeability","Verhagen, H.J.; Jumelet, D.; Vilaplana Domingo, A.; Van Broekhoven, P.","","2011","In de Van der Meer formulas for armour stability the Notional Permeability is used as a parameter. Unfortunately the physical basis of this parameter is weak. It is therefore suggested to use a relation between the Notional Permeability P and the reduction of wave run-up due to infiltration into the breakwater. The advantage is that the latter can be computed with VOF models. This makes is possible to estimate the value of P from mathematical models. Also the run-up reduction can be measured in a physical model, which has the advantage that physical tests for run-up are much faster to execute than models for armour stability.","notionhal permeability; breakwater stability; armour stability","en","conference paper","American Society of Civil Engineers (ASCE)","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:8195c98e-9725-4d86-bc4d-c6979a3f2a75","http://resolver.tudelft.nl/uuid:8195c98e-9725-4d86-bc4d-c6979a3f2a75","Stone Stability in Non-uniform Flow","Hoan, N.T.; Stive, M.J.F.; Booij, R.; Hofland, B.; Verhagen, H.J.","","2011","This paper presents the results of an experimental study on stone stability under nonuniform turbulent flow, in particular expanding flow. Detailed measurements of both flow and turbulence and the bed stability are described. Than various manners of quantifying the hydraulic loads exerted on the stones on a bed are extensively reviewed and extended. On the basis of the data, a new relationship between flow parameters and bed damage—expressed as a stone entrainment formula—has been established for nonuniform flow. As the present data is in line with existing data on other flows, the present relation seems applicable for other types of nonuniform flow as well. Such a relationship could provide more consistent design criteria and allow an estimate of the cumulative damage over time, which is important for making decisions regarding maintenance frequency and lifetime analysis of hydraulic structures.","stone stability; stone transport; stone entrainment; incipient motion; threshold condition; bed protection; decelerating flow","en","journal article","American Society of Civil Engineers","","","","","","","2011-12-01","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:84aab46c-477a-4fe6-aac1-44a638df1275","http://resolver.tudelft.nl/uuid:84aab46c-477a-4fe6-aac1-44a638df1275","Oblique wave transmission through rough impermeable rubble mound submerged breawaters","VanLishout, V.; Verhagen, H.J.; Troch, P.","","2011","There is a growing interest in the application of submerged rubble mound breakwaters as coastal defence structures. As their defensive ability highly depends on the amount of wave energy remaining at their lee side, the accurate prediction of the energy in the lee of such structures is of utmost importance. Past experiments have shown that the behaviour of rough permeable rubble mound structures under oblique wave attack was found to be significantly different from that of smooth impermeable low crested structures. This behavioural difference has led to the research objective of this present study which is to investigate oblique wave transmission by rough impermeable rubble mound submerged breakwaters using 3D physical model tests. This study intentionally uncouples two parameters, being the permeability of the core and the roughness of the breakwater. Analysing the data of this study shows that the permeability of the core has no visible influence on the structure's behaviour with respect to the influence of oblique wave attack. The fully permeable rough rubble mound breakwater behaves analogous to the fully impermeable rough rubble mound breakwater","oblique wave transmission, submerged rubble mound breakwaters, physical 3D model","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:13a2ed14-ae75-436c-883b-11d9b5f015cb","http://resolver.tudelft.nl/uuid:13a2ed14-ae75-436c-883b-11d9b5f015cb","Plaque characterization in ex vivo MRI evaluated by dense 3D correspondence with histology","Van Engelen, A.; De Bruijne, M.; Klein, S.; Verhagen, H.; Groen, H.; Wentzel, J.; Van der Ligt, A.; Niessen, W.","","2011","Automatic quantification of carotid artery plaque composition is important in the development of methods that distinguish vulnerable from stable plaques. MRI has shown to be capable of imaging different components noninvasively. We present a new plaque classification method which uses 3D registration of histology data with ex vivo MRI data, using non-rigid registration, both for training and evaluation. This is more objective than previously presented methods, as it eliminates selection bias that is introduced when 2D MRI slices are manually matched to histological slices before evaluation. Histological slices of human atherosclerotic plaques were manually segmented into necrotic core, fibrous tissue and calcification. Classification of these three components was voxelwise evaluated. As features the intensity, gradient magnitude and Laplacian in four MRI sequences after different degrees of Gaussian smoothing, and the distances to the lumen and the outer vessel wall, were used. Performance of linear and quadratic discriminant classifiers for different combinations of features was evaluated. Best accuracy (72.5 ± 7.7%) was reached with the linear classifier when all features were used. Although this was only a minor improvement to the accuracy of a classifier that only included the intensities and distance features (71.6 ± 7.9%), the difference was statistically significant (paired t-test, p<0.05). Good sensitivity and specificity for calcification was reached (83% and 95% respectively), however, differentiation between fibrous (sensitivity 85%, specificity 60%) and necrotic tissue (sensitivity 49%, specificity 89%) was more difficult.","atherosclerosis; segmentation; quantification; pattern recognition","en","conference paper","SPIE","","","","","","","","Applied Sciences","Imaging Science and Technology","","","",""
"uuid:cd20db3c-2bac-4a53-be88-20c72125abf5","http://resolver.tudelft.nl/uuid:cd20db3c-2bac-4a53-be88-20c72125abf5","Erosion due to high flow velocities: A description of relevant processes","Bisschop, F.; Visser, P.J.; Van Rhee, C.; Verhagen, H.J.","","2010","Convential models for the erosion of non-cohesive sediments overestimate the erosion rate induced by high flow velocities. These high flow velocities occur, for instance, in breaching of embankments or dunes (flow velocities up to 10 m/s) or in jetting sand with a trailing suction hopper dredger (30 to 60 m/s). At these very large flow velocities the erosion process is significantly influenced by the properties of the soil mass (non-cohesive particles). Governing parameters at higher flow velocities are dilatancy, permeability and the (un)drained shear strength of the soil. The sediment concentration in the water also influences the erosion process, especially in case of higher erosion rates. Based on the concept of Van Rhee (2007, 2010) a simple analytical formula is derived that gives a clear insight into the parameters influencing hindered erosion. The concept of hindered erosion is explained by two properties of granular soils: dilatancy and permeability. This implicates that the erosion behaviour of granular soils cannot be described by the behaviour of single particles alone. The properties of the whole soil mass should be considered in predicting erosion at higher flow velocities. Results of a large-scale breach experiment performed in 1994 in the Zwin Channel in the Netherlands (Visser, 1998) are analyzed to evaluate the formula.","(hindered) erosion; granular sediments; breching; jetting","en","conference paper","ASCE - Texas Digital Library","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:3c314e56-c15a-4e2f-93cf-788589f79dab","http://resolver.tudelft.nl/uuid:3c314e56-c15a-4e2f-93cf-788589f79dab","Oblique wave transmission through rough impermeable rubble mound submerged breakwaters","Vanlishout, V.; Verhagen, H.J.; Troch, P.","","2010","There is a growing interest in the application of submerged rubble mound breakwaters as coastal defence structures. As their defensive ability highly depends on the amount of wave energy remaining at their lee side, the accurate prediction of the energy in the lee of such structures is of utmost importance. Past experiments have shown that the behaviour of rough permeable rubble mound structures under oblique wave attack was found to be significantly different from that of smooth impermeable low crested structures. This behavioural difference has led to the research objective of this present study which is to investigate oblique wave transmission by rough impermeable rubble mound submerged breakwaters using 3D physical model tests. This study intentionally uncouples two parameters, being the permeability of the core and the roughness of the breakwater. Analysing the data of this study shows that the permeability of the core has no visible influence on the structure's behaviour with respect to the influence of oblique wave attack. The fully permeable rough rubble mound breakwater behaves analogous to the fully impermeable rough rubble mound breakwater.","oblique wave transmission; submerged rubble mound breakwater; physical 3D model","en","conference paper","ASCE - Texas Digital Library","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:a9047362-eb1f-4db1-83d8-de5a0bbde86f","http://resolver.tudelft.nl/uuid:a9047362-eb1f-4db1-83d8-de5a0bbde86f","Low-mobility transport of coarse-grained bed material under waves and currents","Van den Bos, J.P.; Verhagen, H.J.; Olthof, J.","","2010","The Paintal (1967) formula can be used to estimate transport rates of coarse-grained bed material (such as stones from a bed protection) under low hydraulic loads just above the threshold of motion; the application however is limited to steady currents. This paper presents research aimed at extending the range of application to a combination of regular non-breaking waves and a steady current.","bed protection; transport; wave-current interaction; turbulence modelling","en","conference paper","ASCE - Texas Digital Library","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:1105a978-9f9b-4d0c-ac3e-6451760081ec","http://resolver.tudelft.nl/uuid:1105a978-9f9b-4d0c-ac3e-6451760081ec","On the effectiveness of mangroves in attenuating cyclone induced waves","Narayan, S.; Suzuki, T.; Stive, M.J.F.; Verhagen, H.J.; Ursem, W.N.J.; Ranasinghe, R.","","2010","A study of the effectiveness of mangroves in attenuating cyclone- induced waves was done using the SWAN 40.81 numerical model. Hydraulic parameters during extreme events and local mangrove vegetation parameters were estimated for the Kanika Sands mangrove island near the upcoming Dhamra Port in Orissa, India. Simplified generic analyses were first conducted to obtain insights into the characteristics and behaviour of the model and the system. These were used to select relevant scenarios for simulations of actual conditions at the case-study site. The mangroves were found to be effective in reducing wave heights at the port behind the island though the effectiveness is limited by its geometry and distance from the port. The presence of vegetation has a marked effect though the effect of a variation in vegetation factor is limited. An optimum cross-shore width range for maximum protection was quantified.","Mangroves; Vegetation Factor; Cyclones; Wave Attenuation","en","conference paper","ASCE - Texas Digital Library","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:2532b50a-4fe4-442e-aa96-412c85477119","http://resolver.tudelft.nl/uuid:2532b50a-4fe4-442e-aa96-412c85477119","Toe rock stability for rubble mound breakwaters","Baart, S.; Ebbens, R.; Nammuni-Krohn, J.; Verhagen, H.J.","","2010","Present design tools, as found in the Rock Manual or Coastal Engineering Manual, for the determination of toe rock size for rubble mound breakwaters are based on test data with a large spread: data is relatively dispersed around the centre and descriptive equations have limited applicability ranges. New research has been undertaken to contribute to a more accurate description of toe rock stability. Flume tests have lead to an empirical design criterion for toe bunds in very shallow water based on the Hudson-type stability number. Herein the foreshore slope turns out to have an important influence. An approach with theoretical background has been used for toe bunds in surging wave conditions. The resulting stability description, based on local flow velocities, has been verified with existing data sets. Additional flume tests were performed to measure flow velocities at the toe bund. Results are used to calibrate the velocity-approach, providing an improved design criterion.","rubble mound breakwaters; toe structure; toe bund; rock stability; wave load; foreshore slope","en","conference paper","ASCE - Texas Digital Library","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:13d9203a-eafc-4dd8-a58d-4b2a6e7cd172","http://resolver.tudelft.nl/uuid:13d9203a-eafc-4dd8-a58d-4b2a6e7cd172","Hydraulic performance of elastomeric bonded permeable revetments and subsoil response to wave loads","Oumeraci, H.; Staal, T.; Pfoertner, S.; Kudella, M.; Schimmels, S.; Verhagen, H.J.","","2010","Elastomeric bonded permeable revetments, also called PBA (Polyurethane bonded aggregate) revetments, are highly porous structures made of mineral aggregates (e.g. crushed stones) which are durably and elastically bonded by polyurethane (PU). Despite their numerous advantages as compared to conventional revetments and the large experience available from more than 25 pilot projects, physically-based design formulae to predict their hydraulic performance, wave loading and response are still lacking. Therefore, the present study aims at improving the understanding of the processes involved in the interaction between wave, revetment and foundation, based on large-scale model tests performed in the Coastal Research Centre (FZK), Hannover/Germany, and to provide prediction formulae/diagrams. This paper is focused on the prediction of the hydraulic performance (wave reflection, wave run-up and run-down) and the response of the sand core (pore pressure) beneath the revetment for a wide range of wave conditions, including the analysis of an observed failure due to transient soil liquefaction.","Bonded permeable revetments; wave reflection; wave run-up and run-down; wave-induced pore pressure; failure; transient soil liquefaction","en","conference paper","ASCE - Texas Digital Library","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:71e7460b-61e8-476e-ab1b-c2e61e2e296c","http://resolver.tudelft.nl/uuid:71e7460b-61e8-476e-ab1b-c2e61e2e296c","Optimal inspection planning with time-dependent reliability analysis, application to rubble-mound breakwaters","Nguyen, D.V.; Van Gelder, P.H.A.J.M.; Verhagen, H.J.; Vrijling, J.K.","","2010","In order to avoid failure in its lifetime, a breakwater system has to be inspected and, if necessary, has to be repaired. In this paper, a comprehensive maintenance strategy with optimal inspection planning is formulated. Rational maintenance decision-making approaches are discussed. The proposed maintenance strategy combines time-dependent and condition-dependent maintenance with event-dependent inspection. Optimal inspection planning is obtained by cost optimization with a safety constraint. In practical cases, it is possible to achieve an optimal inspection plan when relevant parameters of strength and load are existing and available.","breakwaters; probabilistic analysis; inspection planning; cost optimisation; maintenance strategy","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:b09dff89-88ad-4c7b-a7b0-15685db27a24","http://resolver.tudelft.nl/uuid:b09dff89-88ad-4c7b-a7b0-15685db27a24","New developments in toe berm design for breakwaters","Verhagen, H.J.","","2010","In the ROCK MANUAL (2007) some guidance is given for the design of toes for breakwaters. However, for very shallow toes, as well as for very wide toes (or berms) this guidance is only marginally. Recently a number of shallow berms and toes have been constructed, partly with the intention to lower the height of the breakwater. These works showed the need for further research on this topic. Errata: In equation 3 a power 3 is missing behind the brackets in the left part and on de bottom of page 7 is referred to figure 596 of the rock manual, this has to be figure 5.69.","breakwater; toe stability","en","conference paper","PIANC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:1cd8f54f-596f-44e8-9fad-42da7c6efbda","http://resolver.tudelft.nl/uuid:1cd8f54f-596f-44e8-9fad-42da7c6efbda","The KNOMAD Methodology for Integration of Multi-Disciplinary Engineering Knowledge within Aerospace Production","Curran, R.; Verhagen, W.J.C.; Van Tooren, M.J.L.","","2010","The paper is associated with the integration of multi-disciplinary knowledge within a Knowledge Based Engineering (KBE)-enabled design framework. To support this integration effort, the KNOMAD methodology has been devised. KNOMAD stands for Knowledge Optimized Manufacture And Design and is a methodology for the analytical utilisation of multi-disciplinary engineering knowledge within design. The KNOMAD acronym can also be used to highlight KNOMAD’s formalized process of: (K)nowledge capture; (N)ormalisation; (O)rganizations; (M)odelling; (A)nalysis; and (D)elivery. The main contribution of the paper is to highlight the development of the KNOMAD methodology and to substantiate its individual steps with sufficient detail to support the application of KNOMAD in practice.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:e30c6f8c-bdb2-44e6-afd5-d4f7c911ece8","http://resolver.tudelft.nl/uuid:e30c6f8c-bdb2-44e6-afd5-d4f7c911ece8","Optimal inspection strategy for rubble-mound breakwaters with time-dependent reliability analysis","Nguyen, D.V.; Van Gelder, P.H.A.J.M.; Verhagen, H.J.; Vrijling, J.K.","","2010","This paper presents a comprehensive maintenance strategy with optimal inspection planning and its application to rubble mound breakwaters. In order to fulfil designated functions, a breakwater has to be inspected during its lifetime and has to be repaired if necessary. Actions of inspecting and repairing form a maintenance strategy. In the paper rational maintenance decision-making approaches are discussed. The proposed maintenance strategy combines time-dependent and condition-dependent maintenance with event-dependent inspection. Optimal inspection planning is obtained by cost optimization with a safety constraint. In practical cases, it is possible to achieve an optimal inspection plan when relevant parameters of strength and load are existing and available.","breakwaters; probabilistic analysis; reliability analysis; cost optimisation; maintenance strategy","en","conference paper","Taylor & Francis, UK","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:8c292108-00b3-4b64-aca3-bb595e5d6618","http://resolver.tudelft.nl/uuid:8c292108-00b3-4b64-aca3-bb595e5d6618","A database of major breakwaters around the world","Allsop, N.W.H.; Cork, R.S.; Verhagen, H.J.","","2009","This paper introduces a co-operative project between HR Wallingford UK (HRW) and Delft University of Technology, Netherlands, (TUD) to develop, populate, and then to apply a database on all major breakwaters around the world. It builds on, and revives, similar initiatives that originate in the late 1970s. The paper describes the objectives in developing the database, the structure and content fields of the initial data-base and presents key examples from the work to date. The paper then discusses a number of potential uses of the database and plans for its future development.","breakwater","en","conference paper","Thomas Telford","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:b6625240-ae8a-4d23-acbe-1a09342409d6","http://resolver.tudelft.nl/uuid:b6625240-ae8a-4d23-acbe-1a09342409d6","Recent laboratory tests with elastomeric revetments","Verhagen, H.J.","","2009","A new construction method of Polyurethane (PUR)-bonded revetments has been tested successfully on various locations in Germany, in the Netherlands, in France, and in the UK. See also the presentation of Bijlsma on this ICE breakwater conference. This year a series of large scale test in the GWK-facility in Hannover have been executed. This presentation will focus on the preliminary results.","elastocoast; polyurethane; revetment","en","conference paper","Thomas Telford","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:1b1df2e6-f266-436f-97e8-1e1c33c9eb06","http://resolver.tudelft.nl/uuid:1b1df2e6-f266-436f-97e8-1e1c33c9eb06","Riprap stability for deep water, shallow water and steep foreshores","Verhagen, H.J.; Mertens, M.","","2009","In the Rock Manual [2007] two sets of equations for the determination of rock stability in breakwaters armour layers are presented. One set is the original formula presented by Van der Meer [1988], valid for deep water conditions. This set uses the parameters Hs and Tm. The other set is an adaptation of these formulae, using the parameters H2% and Tm-1,0, and is recommended for shallow water conditions. Tests by Van Gent et al. [2003] have lead to a calibration coefficient slightly different than the original Van der Meer values. Recently the second author [Mertens, 2007] has reanalysed the datasets of Van der Meer and Van Gent, corrected some of the numbers, and explained a part of the differences. This paper tried to unify both sets of formulae and come to one single equation.","Van der Meer equation; breakwater; shallow water","en","conference paper","Thomas Telford","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:42fa4e56-e453-4883-b7d7-2341fa9e575f","http://resolver.tudelft.nl/uuid:42fa4e56-e453-4883-b7d7-2341fa9e575f","Recent laboratory tests with Elastomeric revetments","Verhagen, H.J.","","2009","A new construction method of Polyurethane (PUR)-bonded revetments (Elastocoast) has been tested successfully on various locations in Germany, in the Netherlands, in France, and in the UK. See also the presentation of Bijlsma on this conference. This year a series of large scale test in the GWK-facility in Hannover have been executed. This presentation will focus on the preliminary results, including a large failure due to liquefaction.","elastocoast; revetment","en","conference paper","ICE","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:4947da9b-cf55-44f8-bd5d-94021815a34a","http://resolver.tudelft.nl/uuid:4947da9b-cf55-44f8-bd5d-94021815a34a","Positioning and applications for planet earth","Verhagen, S.; Retscher, G.; Santos, M.C.; Ding, X.L.; Gao, Y.; Jin, S.G.","","2009","GNSS, InSAR and LIDAR are identified as important techniques when it comes to monitoring and remote sensing of our planet Earth and its atmosphere. In fact, these techniques can be considered as key elements of the Global Geodetic Observing System. Examples of applications are: environmental monitoring; volcano monitoring, land slides, tectonic motion, deforming structures, atmosphere modeling, and ocean remote sensing. Hence, it concerns applications at local and regional scales, as well as at global scales. The main issues can be summarized as: need for a better understanding of processes, leading to better models; need for observational material; and adequate modeling techniques","","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:f2c44a11-f9f9-4caf-9a71-5ee70637b6af","http://resolver.tudelft.nl/uuid:f2c44a11-f9f9-4caf-9a71-5ee70637b6af","Improving the GNSS attitude ambiguity success rate with the multivariate constrained LAMBDA method","Giorgi, G.; Teunissen, P.J.G.; Verhagen, S.; Buist, P.J.","","2009","GNSS Attitude Determination is a valuable technique for the estimation of platform orientation. To achieve high accuracies on the angular estimations, the GNSS carrier phase data has to be used. These data are known to be affected by integer ambiguities, which must be correctly resolved in order to exploit the higher precision of the phase observables with respect to the GNSS code data. For a set of GNSS antennae rigidly mounted on a platform, a number of nonlinear geometrical constraints can be exploited for the purpose of strengthening the underlying observation model and subsequently improving the capacity of fixing the correct set of integer ambiguities. A multivariate constrained version of the LAMBDA method is presented and tested here.","","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:eca0feed-2e1b-487b-ae4d-ade794cacd8b","http://resolver.tudelft.nl/uuid:eca0feed-2e1b-487b-ae4d-ade794cacd8b","Medium-distance GPS ambiguity resolution with controlled failure rate","Odijk, D.; Verhagen, S.; Teunissen, P.J.G.","","2009","The goal of Network RTK is to provide users with precise ionospheric corrections in order to conduct fast GPS ambiguity resolution and to get cm-level positioning results over medium-distance baselines. In this paper it is shown that a Network RTK user should apply the ratio test with fixed failure rate, having a threshold value that depends on the model at hand, as to test whether the estimated integer solution can be accepted with sufficient more likelihood than the second-best integer solution. Application of the traditional ratio test (with a fixed threshold value) may namely result in too many wrong fixes and consequently severe positioning errors. However, in the paper it is also demonstrated that the ratio test with fixed failure rate should be applied with care, since its correct performance depends on the correctness of the underlying model.","","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:cd3ef1db-955d-4c77-8088-7dbf78a8643a","http://resolver.tudelft.nl/uuid:cd3ef1db-955d-4c77-8088-7dbf78a8643a","Multiplatform Instantaneous GNSS Ambiguity Resolution for Triple- and Quadruple-Antenna Configurations with Constraints","Buist, P.J.; Teunissen, P.J.G.; Giorgi, G.; Verhagen, S.","","2009","Traditionally the relative positioning and attitude determination problem are treated as independent. In this contribution we will investigate the possibilities of using multiantenna (i.e., triple and quadruple) data, not only for attitude determination but also for relative positioning. The methods developed are rigorous and have the additional advantage that they improve ambiguity resolution on the unconstrained baseline(s) and the overall success rate of ambiguity resolution between a number of antennas.","","en","journal article","Hindawi Publishing Corporation","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:b1dff969-ec24-443a-b846-b989137a081e","http://resolver.tudelft.nl/uuid:b1dff969-ec24-443a-b846-b989137a081e","The future of single-frequency integer ambiguity resolution","Verhagen, S.; Teunissen, P.J.G.; Odijk, D.","","2009","The coming decade will bring a proliferation of Global Navigation Satellite Systems (GNSSs) that are likely to enable a much wider range of demanding applications compared to the current GPS-only situation. One such important area of application is single-frequency real-time kinematic (RTK) positioning. Presently, however, such systems lack real-time performance. In this contribution we analyze the ambiguity resolution performance of the single-frequency RTK model for different next generation GNSS configurations and positioning scenarios. For this purpose, a closed form expression of the single-frequency Ambiguity Dilution of Precision (ADOP) is derived. This form gives a clear insight into how and to what extent the various factors of the underlying model contribute to the overall performance. Analytical and simulation results will be presented for different measurement sce arios. The results indicate that low-cost, single-frequency GalileoCGPS RTK will become a serious competitor to its more expensive dual-frequency cousin.","ADOP; ambiguity resolution; single-frequency RTK","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:6fb8b968-5682-4b78-9faa-ae5c7b7dcc71","http://resolver.tudelft.nl/uuid:6fb8b968-5682-4b78-9faa-ae5c7b7dcc71","Geodetic sensor systems and sensor networks: Positioning and applications","Verhagen, S.; Grejner-Brzezinska, D.; Retscher, G.; Santos, M.; Ding, X.; Gao, Y.; Jin, S.","","2009","This contribution focuses on geodetic sensor systems and sensor networks for positioning and applications. The key problems in this area will be addressed together with an overview of applications. Global Navigation Satellite Systems (GNSS) and other geodetic techniques play a central role in many applications like engineering, mapping and remote sensing. These techniques include precise positioning, but also research into non-positioning applications like atmospheric sounding using continuously operating GNSS networks. An important research area is multi-sensor system theory and applications to airborne and land-based platforms, indoor and pedestrian navigation, as well as environmentalmonitoring. The primary sensors of interest are GNSS and inertial navigation systems. Furthermore, Interferometric Synthetic Aperture Radar (InSAR) is recognized as one of the most important state-of-the-art geodetic technologies used for generation of Digital Elevation Models and accurately measuring ground deformations","current research issues; GNSS; InSAR","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:965082d0-fbbf-4056-9d08-40348a17965c","http://resolver.tudelft.nl/uuid:965082d0-fbbf-4056-9d08-40348a17965c","Integer ambiguity resolution with nonlinear geometrical constraints","Giorgi, G.; Teunissen, P.J.G.; Verhagen, S.; Buist, P.J.","","2009","Integer ambiguity resolution is the key to obtain very accurate positioning solutions out of the GNSS observations. The Integer Least Squares (ILS) principle, a derivation of the least-squares principle applied to a linear system of equations in which some of the unknowns are subject to an integer constraint,was demonstrated to be optimal among the class of admissible integer estimators. In this contribution it is shown how to embed into the functional model a set of nonlinear geometrical constraints, which arise when considering a set of antennae mounted on a rigid platform. A method to solve for the new model is presented and tested: it is shown that the strengthened underlying model leads to an improved capacity of fixing the correct integer ambiguities.","constrained methods; GNSS; integer ambiguity resolution","en","conference paper","Springer","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:f74137e0-95b5-437b-a23f-6bb966606a8f","http://resolver.tudelft.nl/uuid:f74137e0-95b5-437b-a23f-6bb966606a8f","Bodembeschermingen bij afmeerplaatsen","Verhagen, H.J.","","2009","Rijkswaterstaat, Dienst Utrecht heeft via een opdrachtaanvraag dd. 2 april 2009 de Sectie Waterbouwkunde van de TU Delft gevraagd om “advisering met betrekking tot de ontwerpaspecten van de renovatie van meerplaatsen langs het Amsterdam-Rijnkanaal (UTI-7253), in het bijzonder het geven van een visie op de vertaling van de algemene bestekseisen naar de uitgangspunten voor het ontwerp en aandachtspunten voor de beoordeling van het ontwerp”.","afmeerplaats; bodembescherming; Amsterdam-Rijnkanaal","nl","report","TU Delft","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:7222834a-bdd3-404a-afb7-5551b5419eb0","http://resolver.tudelft.nl/uuid:7222834a-bdd3-404a-afb7-5551b5419eb0","Elastomeric revetments: A new way of coastal protection","Verhagen, H.J.","","2009","A new construction method of Polyurethane (PUR)-bonded revetments has been tested successfully as stable breakwater constructions on various locations in Germany (“Hamburg Hallig”, “Holm Gröde”), as dike revetment in the Netherlands (breakwater revetment in Zuidbout and Petten), as shoreline protection in France (canal embankment near Le Havre), and a maintenance solution in the UK (open stone asphalt revetment repaired in Holland-on-Sea). This paper focuses on the research related to stability and environmental soundness of PUR-bounded revetments.","elastocoast; polyurethane; revetment","en","conference paper","Aquaterra","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:9a668b83-39c4-4dcd-a438-c936b090c526","http://resolver.tudelft.nl/uuid:9a668b83-39c4-4dcd-a438-c936b090c526","Hydrodynamics and morphodynamics of a seasonally forced tidal inlet system","Lam, N.T.; Stive, M.J.F.; Wang, Z.B.; Verhagen, H.J.; Thuy, V.T.T.","","2008","Hydrodynamics and morphodynamics of a seasonally forced tidal inlet system are investigated using numerical models. The ocean forcing including tidal and wave actions and sediment transport is simulated using Delft3D model. Fluvial processes in Delft3D are taken into account as results from SOBEK RURAL model. Analysis of the numerical simulation results allows enhancing insight the mechanisms behind the behaviours of the tidal inlet system in a tropical monsoon area, under the influences of river flow and seasonal wave actions.","tidal inlet; sobek; Vietnam; hydrodynamics; morphodynamics; monsoon","en","journal article","Hanoi Water Resources University","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:3033f2e9-d3b1-4ea8-9aa4-1eb94e517f53","http://resolver.tudelft.nl/uuid:3033f2e9-d3b1-4ea8-9aa4-1eb94e517f53","Individual overtopping events at dikes","Bosman, G.; Van der Meer, J.W.; Hoffmans, G.; Schüttrumpf, H.; Verhagen, H.J.","","2008","Recently, formulae have been derived for maximum flow depths and velocities on the crest and inner slope of dikes or levees at wave overtopping. Two independent physical model test programs in different wave flumes showed, however, a large difference in the results. The present paper clarifies this discrepancy and shows that the empirical coefficients are dependent on the gradient of the outer slope. Subsequently, a formula for the overtopping time was created, based on the difference between fictive wave run-up and crest freeboard. The overtopping time appeared not to be a function of the outer slope. The variation of flow depth and velocity in time can be approached with a linear function.","run-up; overtopping","en","conference paper","World Scientific","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:737bfd8a-2447-45a4-b4e9-98243bb6bf0b","http://resolver.tudelft.nl/uuid:737bfd8a-2447-45a4-b4e9-98243bb6bf0b","Preliminary study of pur-revetment's application","Gu, D.; Verhagen, H.J.; Van de Ven, M.","","2008","PUR-revetment is a newly developed method for hydraulic application. Its structure is similar to that of open stone asphalt revetment, but the crushed stones are glued by polyurethane (PUR) instead of bitumen. To study the feasibility of applying PUR-revetment, a research based on the comparisons between PUR-revetment and open stone asphalt revetment was carried out, for which, a standard four-point bending frequency sweep test, a standard monotonic three-point bending strength test, a porosity test, a stability on slope test, a wave run-up test, an interface permeability test, a relative resistance to abrasive action test and some calculations in GOLFKLAP were done. It suggests PUR-revetment is applicable in practice.","Elastocoast; polyurethane; revetment","en","journal article","Chinese Centrer for Science and Technology Development","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:017326b9-5cdd-43cd-b6ba-a1f844b8250d","http://resolver.tudelft.nl/uuid:017326b9-5cdd-43cd-b6ba-a1f844b8250d","Proces-based modeling of the overflow induced growth of erosional channels","Tuan, T.Q.; Stive, M.J.F.; Verhagen, H.J.; Visser, P.J.","","2008","A new process-based approach is introduced for a more efficient computation of the overflow-induced growth of an erosional channel in a noncohesive homogeneous narrow landmass such as the breach growth in a sand-dike. The approach is easy to incorporate in a 1D/2DV morphodynamic model to compute the channel growth both vertically and laterally. The flow modeling is based on the shallow water equations. For modeling the channel growth, a set of closed equations describing the channel growth in both vertical and lateral direction has been derived in connection with several new morphologic parameters such as the representative channel width and the channel cross-sectional growth index. The approach has been applied to simulate the breach growth in sand-dikes and the morphological development of wave overwash across sand barriers. The computational results bear fairly good resemblance with existing experimental data.","overwash; breach growth modeling; wave overtopping; breach widening; breach deepening","en","journal article","Elsevier","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:616de6e2-b0ff-4cf0-a530-cd559b33b7f2","http://resolver.tudelft.nl/uuid:616de6e2-b0ff-4cf0-a530-cd559b33b7f2","The effects of co-innovation on the value-time curve: A quantitative study on product level","Beelaerts van Blokland, W.W.A.; Verhagen, W.J.C.; Santema, S.C.","","2008","","value chain; co-innovation; 3C model; value-time curve","en","journal article","Springer","","","","","","","","Aerospace Engineering","","","","",""
"uuid:8a288e06-5f38-4bc3-8716-5e823da6ff06","http://resolver.tudelft.nl/uuid:8a288e06-5f38-4bc3-8716-5e823da6ff06","Breakwater stability with damaged single layer armour units","De Rover, R.; Verhagen, H.J.; Van den Berge, A.; Reedijk, B.","","2008","The effect of single layer interlocking armour unit breakage on the hydraulic armour layer stability and potential damage progression is addressed in this paper. A 2-dimensional scale model of a rubble mound breakwater with an armour layer consisting of Xbloc armour units was tested. The residual armour layer stability with broken units was determined. The armour unit displacement and damage progression was assessed. According to the test series breakage of the single layer armour units has a significant negative effect on start of damage of the armour layer. Breakage of units has however no significant effect on failure of the armour layer. This leads to a long and gradual damage progression compared to an armour layer without broken units.","breakwater; xbloc; structural damage; armour units","en","conference paper","World Scientific","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:0303f0df-c763-4584-afa4-ef9470971d3a","http://resolver.tudelft.nl/uuid:0303f0df-c763-4584-afa4-ef9470971d3a","Conceptual design for the breakwater system of the south of Doson naval base: Optimisation versus deterministic design","Viet, N.D.; Verhagen, H.J.; Van Gelder, P.H.A.J.M.; Vrijling, J.K.","","2008","In 2006 a Vietnamese Engineering Consultancy Company carried out a design study of a Naval Base at the location of the South of Doson Peninsula in Vietnam. A deterministic approach applied to the conceptual design of the breakwater system of the Naval Base resulted in a cross-section with a big armour layer and a rather low crest level. This paper applies an economic optimisation approach to derive the optimal geometry for the breakwater system. Results show that when considering total costs over the lifetime of the breakwater system, the block size can be reduced and the crest height can be increased. Some failure to the armour layer can be accepted while the wave transmission and overtopping should be limited in accordance with their related costs.","port infrastructure; rubble mound breakwater; economic opitimisation; reliablility analysis; fault tree","en","conference paper","PIANC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:9d60dd25-aa3f-404d-854f-788f53a44540","http://resolver.tudelft.nl/uuid:9d60dd25-aa3f-404d-854f-788f53a44540","Breach initiation by the response of coastal barriers during storm surges","Tuan, T.Q.; Verhagen, H.J.","","2008","The present paper is concerned with the processes of coastal barrier breaching with focus on the breach initiation induced by high activity of tropical cyclones in the northern and central coast of Vietnam. The breach initiation by the response of coastal barriers during storm surges can also be a common practice encountered in many coasts around the world. A survey of historical breach incidents is first conducted to investigate the major cause and the associated mechanism of coastal breaching. A qualitative description of processes involved is also given. For more quantitative understanding of the breaching potential, a model study on the barrier response of a typical vulnerable spot in the central coast of Vietnam is carried out. The results indicate that wave overwash on barriers in the central coast is inherent and the barrier response during storm surges can increase the barrier breaching potential considerably.","overwash; barrier; breach; storm surge","en","conference paper","Copedec","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:bb32fb23-f7c5-4449-a942-85d5ae87236f","http://resolver.tudelft.nl/uuid:bb32fb23-f7c5-4449-a942-85d5ae87236f","Optimisation of Structural Systems by Appropriately Assigning Probabilities of Failure: Application to Rubble Mound Breakwaters","Viet, N.D.; Verhagen, H.J.; Van Gelder, P.H.A.J.M.; Vrijling, J.K.","","2008","An appropriate assignment of probabilities of failure to subsystems and components in a structural system can bring a minimum of costs and risk. In this paper, a method for economic optimisation of rubble mound breakwaters using pre-assigned probabilities of failure is presented. Application to a design case shows that the proposed method is useful in estimating the optimal design variables in a conceptual design.","breakwaters; probabilities of failure; lifetime cost; economic optimisation; rubble mound breakwater","en","conference paper","PSAM","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:94662043-2b79-484e-aaab-49da31a48e56","http://resolver.tudelft.nl/uuid:94662043-2b79-484e-aaab-49da31a48e56","Seasonal behaviour of tidal inlets in a tropical monsoon area","Lam, N.T.; Stive, M.J.F.; Verhagen, H.J.; Wang, Z.B.","","2008","Morphodynamics of a tidal inlet system on a micro-tidal coast in a tropical monsoon influenced region is modelled and discussed. Influences of river flow and wave climate on the inlet morphology are investigated with the aid of process-based state-of-the-art numerical models. Seasonal and episodic behaviour of the inlet system under the influence of the forcing processes is then described, modelled and explained.","tidal inlet; tidal lagoon; river flow; seasonal effect","en","conference paper","Copedec","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:4a5c608d-daba-4b43-9c5e-292eb594f6be","http://resolver.tudelft.nl/uuid:4a5c608d-daba-4b43-9c5e-292eb594f6be","Estimation of bed protection damage using numerical flow modelling","Hoan, N.T.; Booij, R.; Hofland, B.; Stive, M.J.F.; Verhagen, H.J.","","2008","The current research is aimed at evaluating the applicability of a numerical flow model to predict bed damage. First, an experimental study was carried out to get more inside into the relation between flow forces acting on a bed and the bed response (damage). The experiments were then used as the basis for the evaluation. Second, the flow was modeled using Deft incompressible flow solver developed at Delft University of Technology. Comparison between measurements and calculations of the flow fields shows a good agreement. The velocity distribution is reproduced very well while in most cases the turbulence intensity is underestimated in the bottom region. The measured and calculated stability parameters are in good agreement (error within ±10% ) though. The calculated bed damage (dimensionless entrainment rate, ?E ) has larger error (within ±50% ) due to its high sensitivity to the value of the stability parameters. However, this is reasonably good for bed damage prediction as the measurement of ?E already has an error within ±100% compared to its mean value.","bed stability; decelerated flow; shields; bed roughness","en","conference paper","Copedec","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:9fdac7ea-bd42-49a7-8078-cbc9af9e35e6","http://resolver.tudelft.nl/uuid:9fdac7ea-bd42-49a7-8078-cbc9af9e35e6","Breakwaters and closure dams (2nd edition)","d'Angremond, K.; van Roode, F.; Verhagen, H.J.","","2008","","coastal engineering; breakwaters; closure dams","en","lecture notes","VSSD","978-90-6562-173-3","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:3024123e-66cb-46ba-9f5d-7eedf86eb366","http://resolver.tudelft.nl/uuid:3024123e-66cb-46ba-9f5d-7eedf86eb366","The use of vetivers in coastal engineering","Verhagen, H.J.; Jaspers Focks, D.J.; Algera, A.; Vu, M.A.","","2008","Vetiver grass is a sustainable and innovative solution for the protection of banks. It is shown that Vetiver grass is able to establish a full-stop of bank erosion caused by rapid drawdown. Therefore it provides us with strong indications that it is highly suitable as an anti-erosion measure. A combination of cohesive soil and Vetiver grass provides the best protection against erosion, which implies that it is highly suitable for banks in delta areas, which consist pre-dominantly of cohesive soil. A single hedge of Vetiver grass planted on the outer slope of a dike can reduce the wave run-up volume by 55%, in contrary with sod-forming grasses that give no reduction. Planting multiple hedges along the contour of the outer slope might result in even more reduction. The application of Vetiver grass on existing dikes may provide a substantial reinforcement of these dikes. The advantages of Vetiver grass above conventional methods with the use of stone are numerous: · Vetiver grass is sustainable. Vetiver hedges of over 100 years old have been found. Vetiver grass is not invasive and no significant diseases are known. Vetiver grass will, in contrary with traditional methods, increase in strength in time. · Vetiver grass is an economic attractive solution. In most countries in South-East Asia Vetiver grass can be planted for less than $ 3 per meter, while solutions consisting of stone and concrete are expensive in delta areas. Vetiver grass allows people to protect their own property. Since the costs are low and it is easy to use local initiatives can be easily achieved.","vetiver; bank protection; grass; dikes; revetments","en","conference paper","Copedec","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:7c6f6172-16c6-4be3-a75c-e992259d77fe","http://resolver.tudelft.nl/uuid:7c6f6172-16c6-4be3-a75c-e992259d77fe","A practical method for design of coastal structures in shallow water","Verhagen, H.J.; Van Vledder, G.P.; Eslami Arab, S.","","2008","Modern design formula for coastal structures (like rock stability formula and overtopping formula use wave parameters (H2% and Tm-1,0) which are not readily available from standard boundary condition wave data. For transforming values like Hs and Tp to the parameters used in the new formulas, often-fixed conversion factors are used. However, this may lead to significant errors. Therefore, it is better to calculate these new parameters with an appropriate wave transformation model. The one-dimensional Graphical User Interface for SWAN (SwanOne) is presented as a simple tool to perform the required transformation.","waves; swan; shallow water; wave spectra","en","conference paper","World Scientific","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:9993714a-1128-4954-9044-a8a9d69baff6","http://resolver.tudelft.nl/uuid:9993714a-1128-4954-9044-a8a9d69baff6","Morphodynamics of Hue tidal inlets, Vietnam","Lam, N.T.; Stive, M.J.F.; Verhagen, H.J.; Wang, Z.B.","","2007","Morphodynamics of a tidal inlet system on a micro-tidal coast in a tropical monsoon influenced region is modelled and discussed. Effects of tides, waves, river flows and system configuration on the inlet morphologies are investigated with the aid of process-based state-of-the-art numerical models. Seasonal and episodic behaviour of the inlet system under the influence of the forcing processes is then described, modelled and explained.","tidal inlet; coastal morphology; river runoff; inlet stability","en","conference paper","APAC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:44979315-9fbd-4e00-bd36-9a0f1003e101","http://resolver.tudelft.nl/uuid:44979315-9fbd-4e00-bd36-9a0f1003e101","Decelerating open-channel flow in a gradual expansion","Hoan, N.T.; Booij, R.; Stive, M.J.F.; Verhagen, H.J.","","2007","The velocity and turbulence distributions of decelerating open-channel flow in a gradual expansion were measured using LDV equipment. The results show that the logarithmic law can describe the mean velocity in the bottom region well while the Coles’ law can be applied to the outer region. The shear velocity can be determined both by the logarithmic fit of the mean velocity and by the fit of the Reynolds stress distributions. The turbulence intensities reach their maximum values at z/h = 0.1 to z/h = 0.15. The turbulence intensities do increase along the expansion, especially in the outer region. This is more pronounced for larger Reynolds numbers. Both turbulence intensity and Reynolds stress distributions are found to deviate from the theoretical and empirical curves reported for uniform flow. This can be attributed to the secondary currents generated in the relatively narrow channel.","decelerating flow; bed turbulence; bed shear stress","en","conference paper","APAC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:13d94dab-51b5-47b0-953e-efff4e38a7d8","http://resolver.tudelft.nl/uuid:13d94dab-51b5-47b0-953e-efff4e38a7d8","Morphodynamics of Hue tidal inlets","Lam, N.T.; Stive, M.J.F.; Verhagen, H.J.; Wang, Z.B.","","2007","Morphodynamics of a tidal inlet system on a micro-tidal coast in a tropical monsoon influenced region is modeled and discussed. Effects of tides, waves, river flows and system configuration on the inlet morphologies are investigated with the aid of process-based state-of-the-art numerical models. Seasonal and episodic behavior of the inlet system under the influence of the forcing processes is then described, modelled and explained.","tidal inlet; morhpodynamics; numerical model; Vietnam","en","conference paper","Water Resources University Hanoi","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:1f865e30-eda2-450f-821b-6ceb6e228301","http://resolver.tudelft.nl/uuid:1f865e30-eda2-450f-821b-6ceb6e228301","Scour around an offshore windturbine","Louwersheimer, W.F.; Verhagen, H.J.; Olthof, J.","","2007","During the construction of the first Dutch offshore wind farm prototype measurements were performed. These measurements were aimed to monitor the behaviour of the granular filter layer of the scour protection around the mono-piles upon which the wind turbines are founded. These measurements were compared to scale model test results and theoretical analysis. The measurements show an overall lowering of the filter bed surface during the period that the filter beds were exposed to hydraulic loading of waves and tidal flow.","wind turbine; scour; bed protection; field observations","en","conference paper","World Scientific","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:2b24e555-bfe5-4600-a0da-8147717cd1da","http://resolver.tudelft.nl/uuid:2b24e555-bfe5-4600-a0da-8147717cd1da","On the use of the fictitious wave steepness and related surf-similarity parameters in methods that describe the hydraulic and structural response to waves","Heineke, D.; Verhagen, H.J.","","2007","To assess the hydraulic performance of coastal structures - viz. wave run-up, overtopping and reflection - and to evaluate the stability of the armour layers, use is made of the dimensionless surf similarity parameter, as introduced by Battjes (1974). The front side slope of the structure and the wave steepness are combined in this parameter, also called the Iribarren number. The introduction of the wave steepness was based on the wish to include the effect of the wave period, T, in the surf similarity parameter and hence in the various methods that describe the hydraulic and structural response to waves. The wave steepness to be used in the various methods is the fictitious wave steepness: the ratio of the wave height at the toe of the structure (H) and the fictitious deep-water wavelength (Lo), or rather, the squared value of the local wave period, multiplied by g/2 pi. In deep water the fictitious wave steepness equals the real wave steepness (Ho/Lo), but this is not the case in shallow water, H/Lo is not H/L. The characteristic wave period of a wave field travelling into shallow water is subject to change, due to bathymetry, initial wave breaking, etc. Using the real deep-water wavelength in the expression for the fictitious wave steepness may, therefore, lead to incorrect conclusions when evaluating the key response characteristics in (very) shallow water. To avoid ambiguities and mistakes, it is therefore suggested to refrain from using the wavelength in the expression of the fictitious wave steepness, but to rather only use the local wave period: so = 2 pi Hs/(gT2). A logical next step would be to use ""sf"" as the notation for the fictitious wave steepness.","surf similarity parameter; wave steepness; Van der Meer equation","en","conference paper","World Scientific","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:c241f58e-c948-4d59-9e9b-7134beafbfda","http://resolver.tudelft.nl/uuid:c241f58e-c948-4d59-9e9b-7134beafbfda","Stone stability under decelerating open-channel flow","Hoan, N.T.; Booij, R.; Hofland, B.; Stive, M.J.F.; Verhagen, H.J.","","2007","The current research is aimed at finding a proper relation between flow forces acting on the bed and the bed response. To this end, experiments were carried out in which both the bed response (quantified by a dimensionless entrainment rate) and the flow field (velocity and turbulence intensity distributions) are measured. The three available stability parameters, which are used to quantify for the flow forces, were evaluated using the measured data. The focus of the evaluation is on the correlation of these stability parameters with the measured bed damage expressed in terms of the dimensionless entrainment rate. The experimental results confirm that the Shields stability parameter fails to predict bed damage for non-uniform flow conditions (R2=0.18). In contrast, the stability parameters of Jongeling et al. (2003) and Hofland (2005) give better damage predictions (R2 = 0.77). The results confirm the strong influence of the velocity and turbulence intensity distributions on the stability of bed material.","bed protection; stone stability; decelerating flow; turbulence; Shields","en","conference paper","World Scientific","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:ac9c5019-4a53-4c2d-ab3c-e5f294d717be","http://resolver.tudelft.nl/uuid:ac9c5019-4a53-4c2d-ab3c-e5f294d717be","Coastal defence solutions (approach of ComCoast)","Verhagen, H.J.; Visser, P.J.","","2007","Along the North Sea coast, water levels are rising and waves are intensifying due to climate change. The best scientific evidence suggests that both phenomena are likely to accelerate over the coming decades. In some North Sea coastal areas also land is sinking and tidal heights and rates of erosion are increasing. This means that the risk of flooding is increasing while more people are living, working and spending their leisure time within the coastal flood plain. With the pressure to build more housing, planners are considering options for development in coastal areas. Flood risk, the environment and a dynamic coastline have to be balanced with this pressure for development. ComCoast is looking at how we use the coastal flood plain today and is seeking multifunctional solutions for its sustainable use in the future. The ComCoast concept is to create a more gradual transition from sea to land, instead of a traditional single line of water defence. The project is developing innovative flood risk management strategies to include wider social and environmental functions such as recreation, fishing, tourism and habitat creation. This approach aims at to highlight possibilities for developing the coastal area with respect to spatial planning, to benefit local and wider communities as well as maintaining the environment.","climate change; coastal protection","en","conference paper","IOER, Dresden, Germany","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:22600f82-6b18-423a-87c2-2cc0f802aef5","http://resolver.tudelft.nl/uuid:22600f82-6b18-423a-87c2-2cc0f802aef5","Impacts of climate change on the principles of dike design","Verhagen, H.J.","","2007","Dike design is a very traditional craft. Since many generations dikes have been constructed in our part of Europe. After each disaster the dike was rebuilt, and improved. The improvement was always based on the experiences of the previous flood. For example, for many years the design height of a dike was determined as the height of the highest observed flood, plus a certain margin (usually a value in the order of 1 m). Of course, experience had shown that we also had to add some extra freeboard to take care of the wave run-up.","climate change; dikes; revetments","en","conference paper","Elastogran, Lemförde (BASF)","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:c1b00eb3-66a2-40be-ab8c-7417f9c2476d","http://resolver.tudelft.nl/uuid:c1b00eb3-66a2-40be-ab8c-7417f9c2476d","Stone stability under non-uniform flow","Hoan, N.T.; Booij, R.; Hofland, B.; Stive, M.J.F.; Verhagen, H.J.","","2007","The current research is aimed at finding a dimensionless stability parameter for non-uniform flow in which the effect of turbulence is incorporated. To this end, experiments were carried out in which both the bed response (quantified by a dimensionless entrainment rate) and the flow field (velocity and turbulence intensity distributions) are measured. A new stability parameter is proposed, which together with those of Shields [1], Jongeling et al. [2] and Hofland [3] was evaluated using the measured data. The focus of the evaluation is on the correlation of these stability parameters with the measured bed damage expressed in terms of the dimensionless entrainment rate. The experimental results confirm that the Shields stability parameter fails to predict bed damage for non-uniform flow conditions (R2=0.18). In contrast, Jongeling et al. [2], Hofland [3] and our new proposed stability parameters give better damage predictions (R2 = 0.77÷0.81). The results confirm the strong influence of the velocity and turbulence intensity distributions on the stability of bed material.","stone stability; bed protection; non-uniform flow; turbulence; Shields","en","conference paper","Arizona State University","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:86d52acd-20c1-498a-8552-80bca6129db8","http://resolver.tudelft.nl/uuid:86d52acd-20c1-498a-8552-80bca6129db8","Design of closure works","Verhagen, H.J.","van Duijvendijk, J. (contributor)","2007","This chapter discusses the design aspects of estuary and river closures and those of reservoir dams and certain other hydraulic structures. The focus of this chapter is on closures, not on the situation after the closure has been completed.","closure works; dams; reservoirs","en","book chapter","CIRIA","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:aac4bc7d-02a8-4dc3-be46-b32de4510eb3","http://resolver.tudelft.nl/uuid:aac4bc7d-02a8-4dc3-be46-b32de4510eb3","Uncertainties in the design of bed protections near quay walls","Roubos, A.; Verhagen, H.J.","","2007","Design formulas for bed protections in the port of Rotterdam were investigated. Using depthsoundings, the actual level of stability of a quay wall can be compared with the design formulas. The loads on a bottom protection differ, because of diversity in shipping and tidal motion. Therefore a better comparison can be made by resembling the results of the soundings with a probabilistic approach. The model is calibrated by the sounding results and by registrations of mooring and unmooring vessels. From these approaches insight in the influence of each input variable can be derived. By using a combination of probabilistic results and a fault-tree the probability of a scour hole near a quay wall can be calculated. Also the impact of a scour hole on the environment of a quay wall was investigated. With these results a risk based analysis is made to evaluate the different strategies and their consequences.","quay wall; scour; probabilistic analysis","en","conference paper","Black Sea Coastal Association","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:75e05cdb-cfbe-4a27-899b-866ba6a34a6e","http://resolver.tudelft.nl/uuid:75e05cdb-cfbe-4a27-899b-866ba6a34a6e","Morphodynamics of tidal inlets in a tropical monsoon area","Lam, N.T.; Stive, M.J.F.; Verhagen, H.J.; Wang, Z.B.","","2007","Morphodynamics of a tidal inlet system on a micro-tidal coast in a tropical monsoon influenced region is modelled and discussed. Influences of river flow and wave climate on the inlet morphology are investigated with the aid of process-based state-of-the-art numerical models. Seasonal and episodic behaviour of the inlet system under the influence of the forcing processes is then described, modelled and explained.","tidal inlet; Hue; coastal morphology; inlet stability","en","conference paper","Black Sea Coastal Association","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:bddebe5b-7124-41db-ad4b-3bdba6a846c3","http://resolver.tudelft.nl/uuid:bddebe5b-7124-41db-ad4b-3bdba6a846c3","The influence of river floods on coastal inlet morphology","Lam, N.T.; Stive, M.J.F.; Verhagen, H.J.; Wang, Z.B.","","2007","The influence of river flood on the coastal inlet morphology is investigated with the aid of process based state-of-the-art numerical models. Hydrodynamics of tidal inlets during a severe flood situation and behavior of the inlets are described and explained.","tidal inlet; Vietnam; Hue; river flood","en","conference paper","Arizona State University","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:8f66e0c1-4841-468d-808c-0c64079e56fe","http://resolver.tudelft.nl/uuid:8f66e0c1-4841-468d-808c-0c64079e56fe","Breaching vulnerability of coastal barriers under effects of tropical cyclones: A model study on the Hue lagoon - Vietnam","Tuan, T.Q.; Stive, M.J.F.; Verhagen, H.J.","","2006","Under effects of tropical cyclones, the coast is subjected to attack both by surge and wave from the sea and by flooding from the bay. These forces pose a serious breaching threat to natural sea-defence works such as barrier spits, barrier islands, lagoon barriers, etc. on the coast. Unintended breaching can be catastrophic, causing losses of human life and damages to infrastructures and to natural habitats. Understanding of coastal breaching and breaching potential during tropical cyclone events is therefore of great importance to the management of coastal flooding hazards as well as to the design of sea-defence works. In this paper, a model study on breaching vulnerability of the coastal lagoon barrier of Hue-Vietnam during the historical event of the tropical cyclone in 1999 is presented. In spite of scarceness of available data, attempts were successfully made to simulate the barrier profile response and the barrier breaching process under this extreme condition. It is learnt that seaward erosion and severe wave overwash on coastal barriers during storms can considerably narrow and lower the barrier profile and thus exaggerate significantly the barrier breaching potential. The model predictions for the barrier response to wave overwash and the time-dependent breach growth seem realistic and in agreement with available observation data.","barrier breaching; breacing potential; breach growth; lagoon barriers; wave overwash","en","conference paper","Guangdong Economy Publishing House","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:53768609-192a-4fc4-96fb-9b5d038e09b2","http://resolver.tudelft.nl/uuid:53768609-192a-4fc4-96fb-9b5d038e09b2","Morphodynamic modelling for Thuan An inlet, Vietnam","Lam, T.N.; Stive, M.J.; Verhagen, H.J.; Wang, Z.B.","","2006","Thuan An is a tidal inlet located in Vietnam in a tropical monsoon area. The inlet is very dynamic and variable under the influences of not only tides and waves from the sea but also flows and floods from upstream rivers. Therefore, morphodynamic behaviour of the inlet is very complicated and not well understood. Studies on inlet are also facing with problems of data insufficient. As an effort to gain more understanding on the tidal inlet behaviour, this paper presents a study of the inlet morphodynamics using a numerical modelling approach with the applications several modelling packages including DELFT3D and SOBEK-RURAL developed by WL|Delft Hydraulics. SOBEK has been used to simulate properly the floods in the rivers and on the floodplain. DELFT3D has been used to simulated hydrodynamics of the coastal waters and morphodynamics of the inlet. From the results of the numerical modelling experiments, some behavioural patterns of the inlet, like migration of the inlet channel, can be explained.","tidal inlet; hydrodynamics; morphology; numerical modelling","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:a81e01e9-caf8-4b05-b5f7-39b6ca0fa1b6","http://resolver.tudelft.nl/uuid:a81e01e9-caf8-4b05-b5f7-39b6ca0fa1b6","Actuator tests for a large deformable membrane mirror","Hamelinck, R.; Rosielle, N.; Steinbuch, M.; Ellenbroek, R.; Verhagen, M.; Doelman, N.","","2006","In the design of a large adaptive deformable membrane mirror, variable reluctance actuators are used. These consist of a closed magnetic circuit in which a strong permanent magnet provides a static magnetic force on a ferromagnetic core which is suspended in a membrane. By applying a current through the coil which is situated around the magnet, this force is influenced, providing movement of the ferromagnetic core. This movement is transferred via a rod imposing the out-ofplane displacements in the reflective deformable membrane. In the actuator design a match is made between the negative stiffness of the magnet and the positive stiffness of the membrane suspension. If the locality of the influence functions, mirror modes as well as force and power dissipation are taken into account, a resonance frequency of 1500 Hz and an overall stiffness of 1000 N/m for the actuators is needed. The actuators are fabricated and the dynamic response tested in a dedicated setup. The Bode diagram shows a first eigenfrequency of 950 Hz. This is due to a lower magnetic force than expected. A Helmholtz coil setup was designed to measure the differences in a large set of permanent magnets. With the same setup the 2nd quadrant of the B-H curve is reconstructed by stacking of the magnets and using the demagnetization factor. It is shown that the values for Hc and Br of the magnets are indeed lower than the values used for the initial design. New actuators, with increased magnet thickness, are designed and currently fabricated.","electromagnetic; actuator; deformable; mirror; Helmholtz; coil","en","conference paper","SPIE","","","","","","","","Mechanical, Maritime and Materials Engineering","Center for Systems and Control","","","",""
"uuid:5fe73857-ad75-4b76-abe2-4ca391c894e0","http://resolver.tudelft.nl/uuid:5fe73857-ad75-4b76-abe2-4ca391c894e0","Wave overwash at low-crested beach barriers","Tuan, T.Q.; Verhagen, H.J.; Visser, P.J.; Stive, M.J.F.","","2006","To increase physical insight into wave overwash processes at low-crested beach barriers, wave overtopping discharge events rather than the conventional average overtopping discharge need to be quantified. Also, in order to make intelligent use of the many empirical formulations on wave overtopping discharge at breakwaters from literature, a single-valued appropriate slope for a natural beach needs to be derived. To resolve these issues, laboratory experiments of composite-slope low-crested barriers were carried out. The tests deal with overwash on a smooth non-uniform slope on shallow foreshores. The conventional average overtopping discharge concept does not represent the discontinuous character and associated strength of overtopping ow. Instead, e.g. for purposes of morphological modeling, wave overtopping should be treated as an event-based process. In this study, several new parameters such as the wave-averaged overtopping time, the relative total overtopping time, the overtopping asymmetry, the average maximum discharge and the average instantaneous discharge are defined and formulated. A new approach for defining an equivalent slope is proposed in the parameterization of the overtopping discharge that also takes into account effects of the wave period. It is experimentally shown to be an improvement over the conventional approach by Van der Meer (1998), especially eligible for low-crested sandy slopes such as barriers, dikes, dunes, etc on shallow foreshores.","equivalent slope; low crested; shallow foreshores; overwash; event-based; wave overtopping","en","journal article","World Scientific","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:88869901-39dc-4a9f-abe8-d05125d1d702","http://resolver.tudelft.nl/uuid:88869901-39dc-4a9f-abe8-d05125d1d702","The effect of foreshore slope on breakwater stability","Verhagen, H.J.; Reedijk, B.; Muttray, M.","","2006","Experience has shown that stability parameters for breakwater armour are different for steep and shallow foreshores, as well as for deep and shallow water. A change from a deep water spectral information (Tm0) to shallow water spectral information (Tm-1,0) does not completely explains this difference. Tests have shown that stability also depends on parameters not described by the spectrum at the toe of the breakwater. It is suggested that these parameters include for example the skewness of the waves.","steep foreshore; armour stability; shallow water","en","conference paper","World Scientific","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:a1a61379-89ae-4b95-ae21-fb467ff29b80","http://resolver.tudelft.nl/uuid:a1a61379-89ae-4b95-ae21-fb467ff29b80","Wave transmission at low-crested structures using neural networks","Van Oosten, R.P.; Peixó Marco, J.; Van der Meer, J.W.; Van Gent, M.; Verhagen, H.J.","","2006","The European Union funded project DELOS was focused on wave transmission and an extensive database on low-crested rubble mound structures was generated. During DELOS, new empirical wave transmission formulae were derived. These formulae still showed a considerable scatter due to a limited number of parameters included. Neural networks based on a homogeneous database have resulted in a useful prediction model for wave overtopping within the EU project CLASH. The successful methodology of CLASH is applied within this study. The aim of this study is to improve the prediction of wave transmission in comparison to the empirical DELOS formulae with help of a prediction model based on neural networks. This paper gives a overview of the contents of the composed homogeneous database and gives insight in the capacity and accuracy of the final prediction model. The final prediction model includes 9 input parameters, which is more than at present in the existing hand-derived empirical formulae. The prediction model is accurate in predicting wave transmission for both smooth and mound lowcrested structures.","wave transmission; neural network; Delos","en","conference paper","World Scientific","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:09eab1e8-e270-4c08-92aa-98ae7ef4c145","http://resolver.tudelft.nl/uuid:09eab1e8-e270-4c08-92aa-98ae7ef4c145","Advances in one-dimensional numerical breach modeling of sand barriers","Tuan, T.Q.; Verhagen, H.J.; Visser, P.J.","","2006","A hydrodynamic numerical model is formulated to describe the breach erosion process of sandy barriers. The breach flow is based on the system of unsteady shallow water equations, which is solved using a robust upwind numerical approach in conjunction with the Finite Volume Method (FVM). The hydraulic jump is considered as part of the breach flow, which escalates the scour hole development in the breach channel during the early stages. To reliably capture the jump, additional source terms are added to enhance the momentum balance in the flow equations. A three-layer refined scheme is used to compute the current profile and the associated sediment transport rate under the effects of the jump. A new approach to model the breach morphological development is proposed, which involves several new morphologic factors such as the channel characteristic width and the channel growth index. The model is capable of predicting the breach growth in both lateral and vertical directions, including the development of the scour hole. Some understanding of breach growth in coastal sand barriers in general can be drawn out based on the results of model simulation. The model is calibrated using the laboratory dike breach data of Caan (1996) and is verified against the field experimental data of the Zwin’s 94.","breaching; overwash; sand barrir","en","conference paper","CUR- Gouda","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:d04ae18e-6332-4f7d-aac4-ddfa4d68934a","http://resolver.tudelft.nl/uuid:d04ae18e-6332-4f7d-aac4-ddfa4d68934a","Numerical modeling of wave overwash on low-crested sand barriers","Tuan, T.Q.; Verhagen, H.J.; Visser, P.J.; Stive, M.","","2006","For management of coastal breaching hazards it is critical to be able to assess the potential of coastal barrier breaching as a result of wave actions during storm surges (wave overwash). This phenomenon is known as the breach initiation phase; the mechanisms behind this are not very well understood. In the present study, laboratory experiments of mobile-bed (sand) barrier were carried out to increase the understanding of the processes of the barrier response during storm surges and also to generate data for calibrating a new numerical overwash model. A numerical model of the barrier response, which integrates the processes of beach and dune erosion and of wave overwash, has been developed. The approach of the UNIBEST-TC model (Bosboom et al., 2000) was adopted for modelling the processes of beach and dune erosion. For modeling wave overwash new overtopping parameters are introduced, based on the approach of Tuan et al. (2006). The model is capable of simulating the time-dependent barrier response during storm surges with occurrence of moderate to severe overwash. Overwash-induced effects on the cross-shore transport processes are also effectively incorporated. The model has been calibrated with the laboratory data on the barrier response (the barrier profile response and the overwash channel development). The process of the barrier response together with its major morphological features was fairly well predicted.","overwash; breaching; dunes; sand barriers","en","conference paper","World Scientific","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:c94363aa-4505-485f-bf0e-9fabdd5907ae","http://resolver.tudelft.nl/uuid:c94363aa-4505-485f-bf0e-9fabdd5907ae","Incipient motion of coarse particles under regular shoaling waves","Terrile, E.; Reniers, A.J.H.M.; Stive, M.J.F.; Tromp, M.; Verhagen, H.J.","","2005","Incipient motion of coarse particles under regular shoaling waves is examined. Experiments are performed to investigate the effects of bed fluid acceleration on coarse particle stability. By varying wave height, wave period and water depth, combinations of similar peak orbital velocities and weak to strong intra-wave accelerations were created. The particles used in these experiments have two different sizes both of a centimeter order of- magnitude. The data confirm that acceleration is important for the initiation of motion, since combinations of similar orbital velocity and varying acceleration magnitude resulted in no motion, some motion and motion as acceleration increased. Qualitatively we found that initiation of motion occurs at or is very close to the maximum shear stress due to the combined effects of drag / lift and acceleration as introduced by Nielsen and Callaghan [Nielsen, P. and Callaghan, D.P. (2003), Shear stress and sediment transport calculations for swash zone modelling. Coastal Engineering, 47, pp. 347–354]. However, quantitatively their formulation does not lead to convincing discrimination between motion and nomotion. We expect this to be due to the assumption that the coefficients for drag / lift and acceleration in their formulation are taken equal and constant. From literature and from plotting our data against the Keulegan–Carpenter number we expect that these coefficients strongly vary due to flow separation effects. To arrive at a more convincing discrimination between motion and no-motion we introduce a new fluid acceleration descriptor for nonlinear shoaling waves. The combination of this descriptor with a Reynolds number Reg more clearly delineates the regions with particle motion and without particle motion and has the potential to serve as a descriptor of the incipient motion of coarse particles under nonlinear and skewed, regular waves.","incipient motion; skewed waves; wave acceleration; KC-number","en","journal article","Elsevier","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:f1ff0739-6c1d-4a98-85a1-ff5fd00add02","http://resolver.tudelft.nl/uuid:f1ff0739-6c1d-4a98-85a1-ff5fd00add02","The effect of foreshore slope on breakwater stability","Verhagen, H.J.","","2005","In case of coasts with steep foreshores coastal structures suffer more from damage than normally could be expected from given boundary conditions at deep water. For that reason in many guidelines it is recommended to apply a heavier class of rock in those cases; manufacturers of single layer units (like Accropode, Core-loc or Xbloc) recommend a lower Kd value in case of a steep foreshore. Unfortunately until recently there was no insight in the physical processes leading to this extra load. In the stability formula of VAN DER MEER [1988] shallow water and steep foreshores are not considered.","steep foreshore; armour stability; shallow foreshores","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:07c6f2be-3a70-42aa-97b3-894a5770454d","http://resolver.tudelft.nl/uuid:07c6f2be-3a70-42aa-97b3-894a5770454d","The GNSS integer ambiguities: Estimation and validation","Verhagen, S.","Teunissen, P.J.G. (promotor)","2005","The principle of positioning with the Global Positioning System (GPS) is based on determining the distance of at least four GPS satellites to a receiver. For that purpose the so-called code measurements can be used, so that the position of the receiver can be determined up to several meters. In order to allow for navigation with centimeter accuracy, it is however required to use the very precise carrier phase measurements, since the phase of the carrier wave of the GPS signal can be measured up to several millimeters. Unfortunately, a receiver can only measure the phase of the carrier ââ¬â that is the fraction of the wavelength at the time of arrival. The wavelength is approximately 20 centimeters, and it is not known how many complete waves have preceded the one at the time of arrival. Therefore the phase measurements are called ambiguous. And that brings the problem of 'integer ambiguity resolution'. The goal of this research has been to set up a procedure for ambiguity resolution, such that there is a sound theoretical foundation for the estimation as well as the validation procedure. Until now that was not the case. Different approaches have been considered, and it was shown that an optimal method can be set up, based on the new principle of Integer Aperture estimation. But there are also alternative methods, which are computationally more attractive, and for which it has been shown that their solution is close to optimal. Furthermore, it has been shown that the principle of Integer Aperture estimation gives a theoretical foundation for the traditional validation procedures, as used until now. The result of this research is, that there is now a complete theory available, which gives a solution to the problem of integer ambiguity resolution. This allows for the first time to make inferences on the statistical reliability of the estimated ambiguities. This is an important step, since for many applications not only precision but also reliability is a very important measure in order to decide whether or not one can safely use the navigation system.","global navigation satellite systems; integer ambiguity resolution; estimation and validation","en","doctoral thesis","","","","","","","","","Aerospace Engineering","","","","",""
"uuid:b54e4876-3726-4c87-b578-e48304b334ce","http://resolver.tudelft.nl/uuid:b54e4876-3726-4c87-b578-e48304b334ce","Motion threshold of coarse particles under regular shoaling waves","Stive, M.J.F.; Terrile, E.; Reniers, A.J.H.M.; Verhagen, H.J.","","2005","Threshold of motion of coarse particles under regular shoaling waves is studied. Experiments were performed to investigate the effects of bed fluid acceleration on coarse particle stability. By varying wave height, wave period and water depth combinations of similar peak orbital velocities and weak to strong intra-wave accelerations were created. Qualitatively we found that initiation of motion occurs at or is very close to the maximum shear stress due to the combined effects of drag/lift and acceleration as introduced by Nielsen and Callaghan (2003). However, quantitatively their formulation does not lead to convincing discrimination between motion and no motion. We expect this to be due to the assumption that the coefficients for drag/lift and acceleration in their formulation are taken equal. From literature and from plotting our data against the Keulegan-Carpenter number we expect that the coefficients strongly vary caused by flow separation effects.","incipient particle motion; skewed waves; wave acceleration; KC-number; bed stability","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:5454b130-7ca5-4bbc-baf3-4f332fbd03aa","http://resolver.tudelft.nl/uuid:5454b130-7ca5-4bbc-baf3-4f332fbd03aa","Coarse particles' threshold of motion under shoaling waves","Stive, M.J.F.; Reniers, A.J.H.M.; Terrile, E.; Verhagen, H.J.","","2005","The threshold of motion of coarse particles under regular shoaling waves is studied. Experiments are performed to investigate the effects of bed fluid acceleration on coarse particle stability. By varying wave height, wave period and water depth, combinations of similar peak orbital velocities and weak to strong intra-wave accelerations were created. Qualitatively we found that initiation of motion occurs at or is very close to the maximum shear stress due to the combined effects of drag/lift and acceleration as introduced by Nielsen and Callaghan (2003). However, quantitatively their formulation does not lead to convincing discrimination between motion and no motion. We expect this to be due to the assumption that the coefficients for drag/lift and acceleration in their formulation are taken equal and constant. From literature and from plotting our data against the Keulegan-Carpenter number we expect that these coefficients strongly vary due to flow separation effects.","shields; bed shear stress; shoaling waves","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:c97ddbe6-97c4-4ad9-adc9-d4556389f51a","http://resolver.tudelft.nl/uuid:c97ddbe6-97c4-4ad9-adc9-d4556389f51a","Some new developments in the design rules for coastal structures in relation with the new Rock Manual","Verhagen, H.J.","","2005","In 1991 CUR in the Netherlands and CIRIA in the UK have published the ""manual on the use of rock in coastal engineering"", usually referred to as the ""Rock Manual"". This book of 600 pages gave an overview of the state of the art regarding the design of rock structures along coasts. In 1995 CUR published a adapted version of this book, also containing information on closure works and rock structures along rivers. Although the information in these books is not outdated, there was a general feeling that these reference books were not complete any more given the latest developments in the design of coastal structures. Therefore CUR, CIRIA, and also the French Ministry of Public Works (CetMef) have decided to produce an update of these books. The new Rock Manual will be available in 2006, will contain approx. 1200 pages and will be published in English and in French.","rock manual","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:2e2f45fa-d33c-45d5-befc-b755dfc69d3d","http://resolver.tudelft.nl/uuid:2e2f45fa-d33c-45d5-befc-b755dfc69d3d","Capacity building in coastal engineering with a focus to countries in transition","Verhagen, H.J.","","2005","Coastal engineering is a complex art. At this moment a limited number of phenomena can understood with the help of the laws of physics and fluid mechanics. For the remainder, formulas have been developed with limited accuracy. In addition, input data are also limited available, and form another source of uncertainty. Consequently, a sound engineering approach is required, based on practical experience and supported by physical and mathematical models. Standard solutions do not exist in coastal engineering; solutions depend very much on local circumstances as well as the social and political approach towards the coast. Consequently the transfer of coastal engineering knowledge is a complex art as well. Because of the different circumstances, training of engineers from countries in transition therefore has to be different from training of engineers from a country with a strong coastal engineering tradition.","education; training; coastal engineering; capacity building","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:b83e8de9-6c5f-4b0c-b5b6-b7ebcfed5d60","http://resolver.tudelft.nl/uuid:b83e8de9-6c5f-4b0c-b5b6-b7ebcfed5d60","Classical, Innovative and Unconventional Coastline Protection Methods","Verhagen, H.J.","","2004","This paper gives an overview of some recent developments in structures for coastal protection. Single layer units like Accropode and Xbloc are rather popular at this moment; research indicates that also cubes can be placed in single layers. Also the use of heavy aggregates in concrete can be beneficial for the stability and economics. Structures incorporating geotextiles are also becoming more popular, like geocontainers, big bags and geotubes.","cubes; geotextiles; breakwaters; sand bags","en","conference paper","Springer","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:10bf69c9-d892-4ce7-80fa-cedc1ad77cef","http://resolver.tudelft.nl/uuid:10bf69c9-d892-4ce7-80fa-cedc1ad77cef","Application of Duflow for studying hydrodynamics and stability of tidal inlets in the Tam Giang - Cau Hai Lagoon","Lam, N.T.; Verhagen, H.J.; Van der Wegen, M.","","2004","This paper presents an application of an one-dimensional unsteady numerical model DUFLOW for hydrodynamic simulation of a complex lagoon-inlet system in Vietnam. The difficulties due to the lack of data for model boundary conditions is overcome by using sensitivity analysis approach for the uncertainties of boundary conditions. Model results are used for stability analysis of the tidal inlets according to the “cross sectional stability” and “overall stability” criteria proposed by Bruun (1974). Beside of providing results of hydrodynamics, the numerical model can help to investigate system behaviour under the effects of different boundary conditions and providing design parameters for tidal inlet stabilisation.","lagoon; tidal inlet","","journal article","WRU- Hanoi","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:4ec8557e-9a32-482e-8f36-ec3bfabe6a66","http://resolver.tudelft.nl/uuid:4ec8557e-9a32-482e-8f36-ec3bfabe6a66","Stability analysis for tidal inlets of Thuan An and Tu Hien using Escoffier diagram","Lam, N.T.; Verhagen, H.J.; Van der Wegen, M.","","2004","Stability analysis of tidal inlets is very important in providing knowledge on the behaviour of tidal inlet and lagoon systems. The analysis results can help to plan and manage the system effectively as well as to provide information for stability design of the inlets. This paper presents a method of building and applying the Escoffier diagram for tidal inlet stability analysis with tributary inflow. The method bases on the balance of the equilibrium shear stress and actual shear stress of the inlet.","tidal inlet; Vietnam; Escoffier; lagoon","","journal article","WRU- Hanoi","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:03b9a33a-af16-4013-a53c-6a336987d5bd","http://resolver.tudelft.nl/uuid:03b9a33a-af16-4013-a53c-6a336987d5bd","Experimental research on the stability of armour and secondary layer in a single layered Tetrapod breakwater","De Jong, W.; Verhagen, H.J.; Olthof, J.","","2004","Physical model tests were done on an armour of Tetrapods, placed in a single layer. The objective of the investigations was to study the stability of the secondary layer, and to see if the material of this secondary layer could be washed out through the single layer of Tetrapods. It was concluded that secondary armour is not washed out through an undamaged layer of Tetrapods, and that all damage to the secondary layer is related to damage in the primary layer. To prevent damage to the Tetrapod layer, a high placing density is needed. In case of low placing density, the area around the waterline will slide down, creating gaps in the main armour and exposing the secondary layer. Because of this process the placing density in lower sections of the breakwater increases, and consequently also the strength increases at those places.","armour stability; Tetrapod; Single layer","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:42d551a9-a623-4f4c-a683-fb8408065271","http://resolver.tudelft.nl/uuid:42d551a9-a623-4f4c-a683-fb8408065271","Infiltration of overtopping water in a breakwater crest","Verhagen, H.J.; Steenaard, J.; Tuan, T.Q.","","2004","A number of equations has been developed for calculation overtopping quantities over breakwaters, as well as equations to describe the stability of the inner slope. However, not all the water which overtops the outer boundary of the breakwater will reach the inner slope; part of the water is infiltrated in the crest. In this paper data are presented on the percentage of water infiltrating in the crest of the breakwater. The results are compared with the equation presented in the UK overtopping manual.","overtopping; overwash","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:f8abe851-9d94-465d-9e7b-98a875b30286","http://resolver.tudelft.nl/uuid:f8abe851-9d94-465d-9e7b-98a875b30286","Example of the determination of a design storm","Verhagen, H.J.","","2004","Example for the the dataprocessing of wave data in such a way that design values for coastal structures can be determined","Gumbel; Weibull; Extreme wave height; design wave height","en","book chapter","Spon Press","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:3c9b630e-37ef-4c49-9a3f-a4a471353c85","http://resolver.tudelft.nl/uuid:3c9b630e-37ef-4c49-9a3f-a4a471353c85","Analytic solutions for flow in tidal inlets with tributary inflow","Lam, N.T.; Verhagen, H.J.; Van der Wegen, M.","","2004","Hydraulic characteristics of flow in a tidal inlet act an important role in morphological changes of the inlet. In normal conditions, inlet currents flush sediment out of the inlet to maintain its opening against longshore sediment transports that tend to close the inlet. The currents in the inlet are contributed by the tides and also from upstream river inflows as can be seen in many tidal inlets in tropical areas. Stability analysis for those tidal inlets can be done based on analytic solutions of inlet hydraulics. This paper presents a new analytic solution of tidal inlet hydraulics with inertia term and contribution of tributary inflow. The solution is compared with other studies. Based on the analytic solution, stability analysis for tidal inlets can be carried out.","tidal inlet; tidal lagoon; sediment transport","","journal article","WRU- Hanoi","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:27c2abfd-8042-48b2-b129-f29cfdc41286","http://resolver.tudelft.nl/uuid:27c2abfd-8042-48b2-b129-f29cfdc41286","Hydrodynamic modelling of tidal inlets in Hue, Vietnam","Lam, N.T.; Verhagen, H.J.; Van der Wegen, M.","","2003","Application of an one-dimensional numerical model for hydrodynamic simulation of a complex lagooninlet system in Vietnam is presented. Model results help to get a better understanding on the behaviour of the system. Based on the numerical model results and analytic solutions, stability of tidal inlets is evaluated.","tidal inlet; tidal lagoon; Escoffier","en","conference paper","Copedec","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:a0d58a12-2842-4524-933b-ce1f1ccacaf9","http://resolver.tudelft.nl/uuid:a0d58a12-2842-4524-933b-ce1f1ccacaf9","Bowthruster-induced damage","Schokking, L.A.; Janssen, P.C.; Verhagen, H.J.","","2003","The stability of stones in propeller-induced jet wash is still difficult to predict. Especially the trend of bowthrusters increasing in size and power in sea going ships (especially ferries) over the last years may be a reason for concern when dealing with the protection of slopes and beds. But also ships used in inland navigation are using bowthrusters more intensively. Because of high costs of crew, many inland navigation ships try to sail with a minimum of crew. In order to allow mooring with a limited number of staff, the manoeuvrability of the ship has to be improved, which is often done by making a bowthruster in the ship. At this moment near mooring dolphins in the navigable rivers of the Netherlands managers are confronted with damage to the slope protection because of heavy use of bowthrusters. From these the conclusion can be drawn that it is necessary to improve design formulas for the effect of a bowthruster, as also suggested by Römisch and Hering (2002). The second step is then to make a conceptual model of the effect of (propeller-induced) turbulence on the stability of the slope, followed by a systematic set of tests in the lab in order to verify the conceptual model and in order to determine the calibration constants in the conceptual model.","bowthruster; stone stability; scour; jet wash; quays","en","journal article","PIANC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:c821463f-d8d1-4e19-942a-9bbb26e11e63","http://resolver.tudelft.nl/uuid:c821463f-d8d1-4e19-942a-9bbb26e11e63","Computation of a coastal protection, using classical method, the PIANC-method or a full probabilistic approach ?","Verhagen, H.J.","","2003","In a classical design approach to breakwaters a design wave height is determined, and filled in into a design formula. Some undefined safety is added. In the method using partial safety coefficients (as developed by PIANC [1992] and recently also adopted by the Coastal Engineering Manual of the US Army Corps of Engineers [CEM [2003]) the degree of safety is formalised, and safety factors are given. However, because this method is still rather complicated, a Monte Carlo probabilistic approach allows the designer more flexibility and is also able to use predefined safety values.","breakwater; armour stability; probabilistic analysis; monte carlo","en","conference paper","Black Sea Coastal Association","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:114710dd-81a9-480d-99d6-147ded07d6b2","http://resolver.tudelft.nl/uuid:114710dd-81a9-480d-99d6-147ded07d6b2","Design of timber groynes","Perdok, U.; Crossman, M.; Verhagen, H.J.; Howard, S.; Simm, J.","","2003","The performance and durability of timber groynes (or 'groins') is highly dependent on the design and detailing of the structure. Using knowledge and experience developed over generations an effective functional design can be achieved, which may ultimately result in lower whole life costs and provide environmental advantages over alternative materials","groynes; timber; coastal protection","en","conference paper","American Society of Civil Engineers","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:f1eb49b0-45c0-4e53-ae65-0b70fa3c0b71","http://resolver.tudelft.nl/uuid:f1eb49b0-45c0-4e53-ae65-0b70fa3c0b71","Riprap stability on the inner slopes of medium-height breakwaters","Verhagen, H.J.; Van Dijk, B.; Nederpel, A.","","2003","Medium height breakwaters are subjected to a considerable amount of overtopping. This implies the armour on the inner slope has to stable against overtopping waves. Existing equations do lack some basic understanding of the process of starting up movement of rock on the inner slopes. In case one relates the stability of the blocks on the inner slope directly to the waves approaching the breakwater, the model should include not only the wave parameters (e.g. wave height, period, spectral shape, etc.) but also a number of the parameters of the construction, like the roughness, the breakwater height, the permeability, the outer and the inner slope, and many more. When performing such tests, it is not possible to separate the effect of all individual parameters on the stability, unless a very huge number of tests are carried out. Therefore, the idea is to separate the problem into two parts: the incoming wave gives an amount of overtopping over and infiltration into the breakwater the overtopping and the outflow cause an instability of the blocks on the inner slope.","overtopping; stone stability; inner slope","en","conference paper","KVIV","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:9ac88379-73c2-4e19-9255-6665e2d9a00c","http://resolver.tudelft.nl/uuid:9ac88379-73c2-4e19-9255-6665e2d9a00c","A new view on falling aprons","Verhagen, H.J.; Van der Hoeven, M.; Thiel, B.","","2003","In a flume of BallastHam Dredging a falling apron model has been constructed and loaded by current. The tests have been done with different rock sizes, different layer thickness of the top storage of the apron and two different gradings. In summary it was found that for both the narrow graded rock layers as well as for wide graded riprap the final slope of the apron was always 1:2, while the riprap layer reached a thickness equal to dn50. It was also clear from the tests that the slope did not stop the transport of sand on the slope, but retarded it considerably. The process of settlement of the riprap was that the stones did not roll over each other, but that the whole structure moved down, like on an escalator. For the protection of the abutments of the Januma Bridge in Bangladesh also a falling apron has been applied. This apron has been designed according the standard design rules, applying also a (relatively costly) wide grading of rock. In the framework of the maintenance of the structure, yearly surveys are made of the falling apron. These surveys show that also in prototype the slopes reached a steepness of approximately 1:2. A volumetric analysis indicated that also in reality the thickness of the falling apron was in the order of only one layer of stones","falling apron; slope protection","en","conference paper","Copedec","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:dc5f9b51-18c7-450a-af50-78dbb122b94b","http://resolver.tudelft.nl/uuid:dc5f9b51-18c7-450a-af50-78dbb122b94b","Riprap stability on the inner slopes of medium-height breakwaters","Verhagen, H.J.; Van Dijk, B.; Nederpel, A.","","2003","Medium height breakwaters are subjected to a considerable amount of overtopping. This implies the armour on the inner slope has to stable against overtopping waves. Existing equations do lack some basic understanding of the process of starting up movement of rock on the inner slopes. In order to get more insight into this phenomenon a special device has been constructed in the laboratory. In this device it is possible to generate one single, overtopping wave. So with this piece of equipment overtopping of single waves can be repeated several times and a relation can be looked for between the individual plunge and the stability of the individual blocks. In an other research program the relation between the random waves and the individual plunges is investigated. As a follow up the results of damage by individual waves will be combined with the distribution of overtopping water over a breakwater. This combination will result in a damage distribution due to random overtopping. It has been found from the first test series that stability of the blocks can be described as a function of the maximum water velocity on the crest, combined with some geometrical parameters of the inner slope. From this research followed that the crest height and inner slope also had an effect on stability","riprap; inner slope; wave overtopping; breakwaters","en","conference paper","American Society of Civil Engineers","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:e036214b-a014-4dc2-b1a5-8323e5b4f7b5","http://resolver.tudelft.nl/uuid:e036214b-a014-4dc2-b1a5-8323e5b4f7b5","Kennisbank Waterbouw: Eindrapport","Verhagen, H.J.","","2002","Onderzoek naar kennisdissiminatie in de waterbouw en opzet van een kennisbank met toegang tot deze informatie. Uiteindelijk heeft dit project geresulteerd in www.kennisbank-waterbouw.nl.","knowledge dissimination; kennisbank waterbouw; Delft Cluster; DC 03.04.02","nl","report","Delft Cluster","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:b4ec0b6a-78ba-44aa-b87d-9597f91d4ae6","http://resolver.tudelft.nl/uuid:b4ec0b6a-78ba-44aa-b87d-9597f91d4ae6","Influence of the density of placement on the stability of armour layers on breakwaters","Van den Bosch, A.; D' Angremond, K.; Verhagen, H.J.; Olthof, J.","","2002","Studies on the stability of the amour layer (d’Angremond et. al. [1999] revealed the importance of density of placement. The current research focuses on the influence of the density of placement on the stability of cubes in a double armour layer and tetrapods and rocks in a single armour layer. The experiments were performed in the Laboratory of Fluid Mechanics of the Faculty of Civil Engineering and Geosciences at the Technical University Delft. A model of a breakwater was constructed in a wave flume. An increase in density of placement resulted in all cases in an increase of stability, except in the case of cubes. Cubes have the tendency to start behaving like a placed block revetment including the characteristic failure mechanisms like uplift and sliding. Tetrapods seem to be unsuitable for single layer armour layers due to the fact that the filter layer is easily attacked by the waves even when no tetrapod has been removed. Experiments on rock showed that vertically placed elements lead to a much more stable construction due to their self-repairing ability. Characteristic for rock is the piling up of elements under the waterline caused by the impact of collapsing waves. This lead to very low densities of placement higher on the slope. Existing damage criteria are not suitable for density of placement. In this research an effort has been done to create a damage criteria, which considers area of attack, density of placement and different failure mechanisms.","breakwaters; armour stability; placing density","en","conference paper","American Society of Civil Engineers","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:e3bf780f-ac77-4806-a36e-81728aa97020","http://resolver.tudelft.nl/uuid:e3bf780f-ac77-4806-a36e-81728aa97020","Positioning of cubes on a breakwater slope","Verhagen, H.J.; D' Angremond, K.; Van der Vliet, K.","","2002","Recent research has shown that it is possible to use concrete cubes as a single armour layer on breakwaters. However, this is only possible in case a placing density of at least 70 % is achieved. In lab-tests it is no problem to place cubes with this density, however it is questionable if such a placing density can be achieved in prototype situations. A number of tests have been carried out in order to determine the requirements for dropping concrete blocks from a crane onto a breakwater slope. The conclusion is that at a waterdepth of approximately 10 times the block size this just can be achieved and that at smaller depth this placing density can be reached without too many difficulties. However, in all cases a good quality toe is vital for a high placing density. Blocks have to be placed at an angle of 45° with respect to the breakwater axis; blocks placed parallel to the breakwater axis will lead to large voids.","cubes; breakwaters; armour units","en","conference paper","American Society of Civil Engineers","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:4b1ece63-7fe6-4c5d-8f3a-f69082d3f660","http://resolver.tudelft.nl/uuid:4b1ece63-7fe6-4c5d-8f3a-f69082d3f660","Results of the MarCom questionnaire","Verhagen, H.J.","","2002","On request of MarCom a questionnaire has been prepared to investigate the opinion of PIANC members and others about the quality and the usefulness of the MarCom working group reports. The results of this questionnaire were presented and discussed at the Sydney Conference (September 2002).","PIANC","en","conference paper","PIANC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:c7265dcc-b86d-422f-b73c-43e2cb81ec58","http://resolver.tudelft.nl/uuid:c7265dcc-b86d-422f-b73c-43e2cb81ec58","Void porosity measurements in coastal structures","Bosma, C.; Verhagen, H.J.; D'Angremond, K.; Sint Nicolaas, W.","","2002","The paper describes the use of two fundamental design parameters, the void porosity and layer thickness in rock armour constructions. These design parameters are very sensible for factors such as the boundary definition of a rock layer, rock production properties, intrinsic properties and construction properties. Differences in the value of the design parameter cause a considerable (financial) risk. This risk contains two directions, the first is the affection on the hydraulic performance of the structure and the second is its relation with materials procurement. This paper describes and investigates the second risk for the contractor: the large margin in the calculation of the void porosity, which influences the amount of rock (in weight). Often this risk is on account of the contractor, so it is necessary to have better insight in these values in order to reduce the financial risk. Focus is on the variation of the porosity at the bottom, at the top and at the transition between two layers of graded material. This has resulted in correction coefficients for the layer thickness, as well as for the computation of the void porosity as a basis for payment by the client.","filters; porosity; void ratio; bed protection","en","conference paper","American Society of Civil Engineers","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:f846b82a-2532-4560-a538-5501f574e00f","http://resolver.tudelft.nl/uuid:f846b82a-2532-4560-a538-5501f574e00f","Criteria for the selection of breakwater types","Verhagen, H.J.","","2002","In history PIANC has paid quite some attentions to breakwaters, in ancient years results of practical experience have been published in the country presentations at the Conferences, but later some of these papers started to have a more scientific basis. One of the first papers giving a good background on the processes of stability of breakwaters was published on the conference in Rome by IRIBARREN CAVANILLES AND NOGALES [1953]. As usual in those days, the paper does not have a title, but in fact it deals with the stability calculation of armour units. Later more detailed work was published in separate reports, like the ""Final report of the International Commission on the study of Waves"" in 1976.","breakwaters; probabilistic analysis","en","conference paper","PIANC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:3e878f47-56d2-4e38-b44d-9b7fe99b4113","http://resolver.tudelft.nl/uuid:3e878f47-56d2-4e38-b44d-9b7fe99b4113","OMS Ondersteunende omgeving en componenten: GIS inventory","Verhagen, F.Th.; Vermetten, A.","","2002","","GIS, databases, soil, water","en","report","Delft Cluster","","","","","","","","","","","","",""
"uuid:7ff41c0b-e51a-4709-9566-5c914473689a","http://resolver.tudelft.nl/uuid:7ff41c0b-e51a-4709-9566-5c914473689a","Bowthrusters and the stability of a riprap revetment","Verhagen, H.J.","","2001","Because of problems with the design guidelines produced by PIANC for armoured slopes under attack by bowthrusters, additional work has been done in the Netherlands. On the basis of this work computational rules have been developed. However, because of the increase of bowthruster power, more detailed knowledge is needed on the effect of a bowthruster on the stability of a riprap revetment. Especially large, fast vessels will cause problems to shore protection. Recently P&O put into operation the “Pride of Rotterdam”, a luxury ferry with two bowthrusters with a capacity of 2000 kW each. When the captain uses both thrusters simultaneously, there is a considerable risk of damaging the rock of the underwater slope protection. But also with relatively small vessels for inland navigation problems arise when skippers use their bowthrusters. For the calculation of the effect of a bowthruster at this moment the common methodology is to use the hydraulics of a plain jet. This is not correct because the propeller in the tube causes quite some extra turbulence. This extra turbulence will cause extra damage to the shoreline protection. So in a good design formula for the determination of stability in a bowthrusterflow, he effect of additional turbulence of the propeller has to be included.","bowthruster; revetment; stability","en","conference paper","Bulgarian Ship Hydromechanics Centre","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:b9b3defc-1075-499a-974b-ab7eab4dd666","http://resolver.tudelft.nl/uuid:b9b3defc-1075-499a-974b-ab7eab4dd666","Kennisbank waterbouwkunde: Thema kust en rivieren: subthema aansluiting bij de eindgebruiker","Verhagen, H.J.","","2001","","","nl","report","Delft Cluster","","","","","","","","","","","","",""
"uuid:c3f15cf3-439f-45bc-9798-73174470168a","http://resolver.tudelft.nl/uuid:c3f15cf3-439f-45bc-9798-73174470168a","Water injection dredging","Verhagen, H.J.","","2000","Some twenty years ago WIS-dredging has been developed in the Netherlands. By injecting water into the mud layer, the water content of the mud becomes higher, it becomes fluid mud and will start to flow. The advantages of this system are that there is no need of transporting the mud in a hopper, and no need for a pipeline. Also from an energetic point of view the solution is attractive. The system requires however a different way of payment. Most efficient is a maintenance contract with a dredging company in such a way that the company guarantees a given nautical depth for a fixed sum per year. For the port authority it makes budgeting much easier, because the maintenance dredging will become a fixed amount per year. The limitations are that WIS-dredging is only possible in case the material consists mainly of mud, the mud has to be quite clean, and the disposal should not be too far away from the dredging site.","water injection dredging; WIS dredging; densitiy current","en","conference paper","Black Sea Coastal Association","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:6fd610c4-585c-4f97-8bae-1ed65b06df1c","http://resolver.tudelft.nl/uuid:6fd610c4-585c-4f97-8bae-1ed65b06df1c","Sea breeze generated waves on the coast of Varna","Verhagen, H.J.","","2000","For the determination of the stability of coastlines, coastal erosion and the design of erosion protection studies, the “local” wave climate is the most important input parameter. For morphology, “local” means just outside the breaker line. On relatively calm days the local wave climate is strongly influenced by the effect of sea breeze. On the basis of the sea breeze model of HAURWITZ [1947] and HSU [1988] an operational method has been developed for the determination of sea breeze and the effect on coastal morphology. Examples are presented the Bulgarian Black Sea coastline.","sea breeze","en","conference paper","Black Sea Coastal Association","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:83a7f5aa-ad95-4c4b-8b2f-f716ea269f2a","http://resolver.tudelft.nl/uuid:83a7f5aa-ad95-4c4b-8b2f-f716ea269f2a","Probability and port engineering","Verhagen, H.J.","","2000","One of the major problems in the design of coastal structures is that the design has to be based on very uncertain input data. This implies that the degree of uncertainty is an important value for the designer. In traditional design the uncertainty is not really quantified, but an overall “safety factor” is included. The problem of this approach is that the value of the safety margin is not known at all. Therefore an approach in which the uncertainties are quantified has the advantage that one is able to determine how much money is used for being at the safe side, to determine the level of safety, but also it becomes clear what are the most uncertain elements in the design. A probabilistic design method allows quantifying these values","probabilistic analysis; breakwaters","en","conference paper","Black Sea Coastal Association","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:2b166557-0861-4625-b077-52e1dc643d77","http://resolver.tudelft.nl/uuid:2b166557-0861-4625-b077-52e1dc643d77","Comparison and validation of two Dutch models of breach growth in sandy dikes","Ye, S.Q.; Verhagen, H.J.","","1999","In order to develop a new philosophy of flood safety in terms of probability of a certain level, two mathematical models of breach growth in sandy dikes have become available to determine the flood discharge in case of dike failure. BREACHES 1.0, developed at Alkyon/Delft Hydraulics (Steetzel) and BRES 1.0 at Delft University of Technology (Visser) are different in principle. The comparison of these two models with the previous dam breach models was carried out. The validation of the two models using Dutch field sandy-dyke experimental data was conducted, the non-homogeneous fuse plug dam tests in China were also used as validation data. A suggestion to improve the capability of BRES model has been done.","breaching; dikes; breach growth","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:fddcfce5-50c0-40ab-9547-f987fb9f090c","http://resolver.tudelft.nl/uuid:fddcfce5-50c0-40ab-9547-f987fb9f090c","Sea breeze generated waves and coastal morphology","Verhagen, H.J.; Savov, B.","","1999","For the determination of the stability of coastlines, coastal erosion and the design of erosion protection studies, the “local” wave climate is the most important input parameter. For morphology, “local” means just outside the breaker line. On relatively calm days the local wave climate is strongly influenced by the effect of sea breeze. On the basis of the sea breeze model of HAURWITZ [1947] and HSU [1988] an operational method has been developed for the determination of sea breeze and the effect on coastal morphology. Examples are presented from Cartagena, Colombia, and from the Bulgarian Black Sea coastline.","sea breeze; wind generated waves; daily monsoon","en","conference paper","MedCoast","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:66fd16dd-2761-4ccd-96f0-d660ba11c852","http://resolver.tudelft.nl/uuid:66fd16dd-2761-4ccd-96f0-d660ba11c852","Sustainable transfer of coastal engineering knowledge at post graduate level","Verhagen, H.J.; De Vries, W.S.","","1999","Practical problems in the transfer of knowledge and skills to coastal engineers in training, with focus on the training of coastal engineers from developing countries and other countries in transition. The difference between the training of scientists and engineers.","Coastal Engineering; capacity building; training; education","en","conference paper","Copedec","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:20ebfb47-deb4-46bb-9a5c-894bd9c75091","http://resolver.tudelft.nl/uuid:20ebfb47-deb4-46bb-9a5c-894bd9c75091","Policy analysis methodology","Verhagen, H.J.","","1998","Introductory lecture on policy analysis and decision making, with a focus on decision makers in ports and harbours.","decision making; policy analysis; port planning","en","conference paper","Black Sea Coastal Association","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:8457b22f-2f89-4ca3-867e-121ee6405941","http://resolver.tudelft.nl/uuid:8457b22f-2f89-4ca3-867e-121ee6405941","Porto More Resources Assignment Study","Verhagen, H.J.","","1998","Description of a simulation game to study and simulate decision making in a port and harbour environment with both social as well as environmental problems. The simulation game has been developed for a course for Black Sea port managers.","simulation game; decision making; pollution; port development","en","conference paper","Black Sea Coastal Association","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:c66b1807-4c7e-4706-bed8-9272bf3c590e","http://resolver.tudelft.nl/uuid:c66b1807-4c7e-4706-bed8-9272bf3c590e","Dicea Risk analysis in the design of coastal structures","Verhagen, H.J.","","1998","Basic lecture on risk analysis for the design of coastal structures.","risk analysis; probabilistic analysis","en","conference paper","Black Sea Coastal Association","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:7bd48132-26aa-424b-a6ca-7cea948c9b7b","http://resolver.tudelft.nl/uuid:7bd48132-26aa-424b-a6ca-7cea948c9b7b","Education of coastal engineers for the 50th ICCE","Verhagen, H.J.","","1996","In general the problem in education is that we teach nowadays students the knowledge from five years ago, to be applied in the next 5 to 15 years (I admit, the student of today will have reached his retirement when he will participate in the 50th ICCE, the title is exaggerating reality). When one analyses the developments in the profession, it is clear that teaching present day facts is not very useful. We have to teach approaches, design philosophy, concepts, etc. What the meaning is for education of coastal engineers will be worked out in this paper.","education; coastal engineering","en","conference paper","ASCE","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:6cdaf830-d925-4750-b45b-0be353c07095","http://resolver.tudelft.nl/uuid:6cdaf830-d925-4750-b45b-0be353c07095","The requirements for Coastal Engineers in Integrated Coastal Zone Management","Verhagen, H.J.","","1995","Worldwide there is a need for training of engineers to work within the framework of Coastal Zone Management. This has effects on the education of engineers. Moreover, the requirements for an educational program for coastal engineers from developing countries are quite different from the requirements for the training of engineers from the industrialized world. In a university course for engineers from developing countries more attention has to be paid to the development of capabilities to come to practical solutions given the local constraints and to be able to assess the work done by foreign consultants.","coastal zone management; training; capacity building","en","conference paper","Copedec","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:6a033a29-878d-4431-a8e4-94618d329d17","http://resolver.tudelft.nl/uuid:6a033a29-878d-4431-a8e4-94618d329d17","Dutch approach to coastline management","Verhagen, H.J.; Pilarczyk, K.W.; Loman, G.J.A.","","1994","In the Netherlands we have a strong tradition in making zoning regulations, town and country planning, and so on The Ministry of Environmental Affairs, Town and Country Planning and Housing is one of the most important ministries in this country In matters of planning the basis is the ""memorandum on town and country planning"", which is renewed every 10 years and in which the general policy of the government is described This memorandum is prepared by the ministry, in cooperation with other ministries. Preliminary versions are discussed in detail with advisory boards, non-governmental Organisations, lower authorities, etc In this memorandum only the head·lines are given, But even the headlines alone make a thick book The fourth memorandum was published recently, and consists of many volumes In concordance with this ""master plan"", sectorial plans are made by various ministries For example, the plan on Energy-distribution, on Recreation, on Natural Reserves, on Drinking water production, on Sea-defence, etc.","spatial planning; coastal zone management","en","conference paper","PIANC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:86042e5e-0fae-439d-9632-cb1f3c2114e9","http://resolver.tudelft.nl/uuid:86042e5e-0fae-439d-9632-cb1f3c2114e9","De toekomst van een dijk al bij het ontwerp betrekken","Verhagen, H.J.; Struik, P.","","1993","Tegenwoordig is bijna elk probleem bij de versterking van dijken op te lossen door een kunstwerk te maken in plaats van de traditionele grondconstructie. Soms wordt bij de afweging te weinig rekening gehouden met de lange levensduur en de bijzondere aard van' de waterkering'. Dat kan toekomstige generaties met grote problemen opzadelen.","dijken; levensduur","nl","journal article","Land+Water","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:ee5cf5d5-3695-435f-80bc-21fff71b3480","http://resolver.tudelft.nl/uuid:ee5cf5d5-3695-435f-80bc-21fff71b3480","Coastal zone management around the southern North Sea","Hillen, R.; Van de Wetering, B.G.M.; Verhagen, H.J.","","1993","The Southern North Sea is bordered by Great-Britain, France, Belgium, The Netherlands, Germany and Denmark. The North Sea basin and its adjacent shorelines are intensively used. Management of the basin and the coastal zone is therefore essential. Because of the small scale of the area, the dense population and the big scale of the interactions, international cooperation is vital. In this paper an overview is given of both the morphologic-physical interactions and the administrative interactions between the bordering governments. A complicating factor in Coastal Zone Management around the Southern North Sea is that CZM is highly connected to national spatial planning and to sea defence policy. In several of the bordering countries this is not a subject of the national government, but is handled on a regional level. This makes that we are dealing with more authorities involved. At this moment international agreement exists on most aspects of active use of the North Sea basin itself (navigation, oil and gas mining, fishery, cables, etc) and its major coastal shallow areas (like the Waddensea). However in the field of passive use (pollution by inflowing rivers, air contamination by heavy industry, risk by transport and processing of hazardous goods) still much has to be done. International agreement on the recreation along the coastal strip does not yet exist. Also the standards for coastal protection against flooding by storm surges and against chronic erosion vary in each country.","coastal zone management; North Sea; coastal erosion","en","conference paper","ASCE American Society of Civil Engineers","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:f4ce79a9-ce52-4808-a267-3d628ae2e3a0","http://resolver.tudelft.nl/uuid:f4ce79a9-ce52-4808-a267-3d628ae2e3a0","Coastal Management in the Netherlands","Verhagen, H.J.; Pilarczyk, K.W.","","1992","The coast is a very important aspect of life in the Netherlands. 60 % of the Netherlands is below the sea level, everyone lives less than 200 km from a beach, and for most people the sea is less than 50 km away. But in the Netherlands there is officially no Agency for Coastal Zone Management, neither are there laws on Coastal Zone Management. On a first impression this sounds very strange. Of course it is not so strange, knowing the situation in the Netherlands. Because nearly everything in the Netherlands is related to the sea, an Agency for Coastal Zone Management should be involved in nearly all major decisions in the Netherlands. Of course, we have such an agency. It is the council of ministers. And indeed, in fact all matters regarding Coastal Zone Management are decided on a cabinet level.","coastal zone management; coastal protection","en","conference paper","-","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:00df3f55-c3d1-4f18-bc84-609613fdf922","http://resolver.tudelft.nl/uuid:00df3f55-c3d1-4f18-bc84-609613fdf922","Coastal zone management with relation to low investment solutions","Verhagen, H.J.; Yap, J.T.L.","","1992","Copying solutions from the western, industrial countries for application in developing countries is in general not the best solution for solving the problems of developing countries. The main reason for that is that the available resources in the developing world are different from the resources in western countries. In the industrialised countries there is a strong tendency to solve problems in such a way that the amount of required labour decreases. Thus, a capital-intensive solution is searched for. The reason for this is the very costly social system and the high standard of living. This causes a large deference between the hourly income and the hourly costs of labour, which is much less in developing countries. On the other hand it is difficult and expensive to import industrial products from abroad. Also it is difficult to have sufficient financial resources available. For those countries it is more economic and more attractive to search for solutions which require hardly any investments, but are relatively labour-intensive. These solutions generally require often more maintenance. However, increased maintenance costs may even be advisable, provided initial investment is very low. The total cost of the solution, i.e. investment plus maintenance, can be spread over a longer period without financial indebtedness. The above described philosophy is valid in many sectors of society, but is especially true in the coastal zone. Works in the coastal zone are generally of a large scale, requiring a long planning and very often designed using capital intensive methods.","optimal cost; developing countries; low cost solutions; low investment solutions","en","conference paper","PIANC - ITS Surabaya","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:5d24ef34-1698-4860-9d78-8884269f79b2","http://resolver.tudelft.nl/uuid:5d24ef34-1698-4860-9d78-8884269f79b2","Method for artificial beach nourishment","Verhagen, H.J.","","1992","Simple design rule for artificial beach nourishment, as applied in the Netherlands.","beach nourishment","en","conference paper","ASCE","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:82bff86e-f67c-424e-990b-f56bcee39d36","http://resolver.tudelft.nl/uuid:82bff86e-f67c-424e-990b-f56bcee39d36","Design of beach replenishment","Roelse, P.; Verhagen, H.J.","","1991","In the Netherlands much land was captured from the sea. At the same time however along the coast severe losses of land occurred. The main reasons were sea level rise and effects of decreasing tidal volumes of estuaries. Besides there were the local effects of shifting tidal channels and periodical movements of the coastline. Building of groynes, dune-foot revetments and dikes did not stop the loss of sand. On behalf of the increased interests in the coastal area the Dutch government decided in 1990 to stop the coastal erosion. The main measure to achieve this purpose will be artificial beach nourishment. This coastal defense method is in harmony with nature, flexible and cost-effective. This paper deals with the technical aspects of the new coastal policy.","artificial beach nourishment; beach nourishment","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:2fe9b5c9-5ace-4c04-a12f-6ac9c116eb42","http://resolver.tudelft.nl/uuid:2fe9b5c9-5ace-4c04-a12f-6ac9c116eb42","Coastal maintenance in the Netherlands","Verhagen, H.J.","","1991","The government of The Netherlands has decided in the summer of 1990 to maintai.n the coastline at the position of 1990. This will be done mainly by artificial beach nourishment. The costs will be paid by the national government. The purpose of this coastal maintenance is to maintain a sufficient level of safety and to maintain the various functions of beach and dune areas. As a criterion for coastal erosion the movement of the ""coastline"" is used. In this paper the definition of coastline is worked out more in detail.","coastal zone management; artificial nourishment; coastal erosion","en","conference paper","ASCE","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:7f05dd05-49d9-456c-84fa-1099eb8bb421","http://resolver.tudelft.nl/uuid:7f05dd05-49d9-456c-84fa-1099eb8bb421","Coastal protection policy in the Netherlands","Verhagen, H.J.","","1990","The 350 km long Dutch coast along the North Sea is characterized by alternating coastal stretches of accretion and erosion resp. resulting in seaward and landward displacement retreats of the shoreline. Places of accretion and erosion also vary in time. Behind the dunes are low lying polders (very often with a ground level even below the low water line), in which millions of people live. The coastal erosion endangers the strength of the dunes as a sea-defence. Erosion of narrow dunes (at some places the dunes are less then 200 m wide) can therefore not be permitted in the Netherlands. At 40 km of coastline the dunes have no more than 10 m extra width available to cope with the erosion problem. A yearly erosion of only 1 m/year causes big problems within a few years. Since life in the Netherlands is so highly dependent of the quality of the coastal defence, structural solution for this problem must be developed and carried out. In the past the only way to attack the erosion problem was to build groins. Several sections of the Dutch coastline are defended with these constructions (see figure 1). Evaluation of the efficiency of groins as tools for erosion was not stopped by these constructions. More recently (last decades) nourishment of sand beach and front dune has been practised to compensate for the loss of sand dune to erosion.","coastal zone management; coastal erosion; safety levels","en","conference paper","Black Sea Coastal Association","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:390c6e93-7608-419c-840e-063e609546d2","http://resolver.tudelft.nl/uuid:390c6e93-7608-419c-840e-063e609546d2","General strategy on coastline protection: The Dutch case","Louisse, C.; Verhagen, H.J.","Pilarczyk, K.W. (contributor)","1990","Overview of the Netherlands policy on coastal protection and coastal defence","coastal protection; coastal morphology; sea level rise","en","conference paper","Balkema","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:a882eeed-3c73-48c8-b2fb-d68b9f45df29","http://resolver.tudelft.nl/uuid:a882eeed-3c73-48c8-b2fb-d68b9f45df29","The influence on the environment of coastal structures recently built in the Netherlands","Stigter, C.; Verhagen, H.J.; De Vriend, H.J.; Van der Weijde, R.W.; Van Raalten, C.; Loxham, M.","","1990","In the Netherlands today much attention is paid to the effect of coastal structures on the environment. In the past it was usual to quantify the effect of such a structure on its environment solely with the purpose of deciding whether that effect could imply any hazard to the structure itself (or to structures in the neighbourhood). Nowadays environmental impact studies are mainly carried out to see what possible changes the structure may bring about in the integral coastal system. However, changes in the coastal system can only be studied if information is already available regarding that coastal system. Therefore scientists and engineers from various disciplines, such as hydraulic engineering; sedimentology. geology, physical oceanography and marine biology have joined forces to describe and analyze the long·term and large-scale morphological evolution of the Dutch coastal zone as an integrated system.","environmental impact; deltaworks; beach nourishment; dune erosion","en","conference paper","Pergamon - PIANC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:9f02d12a-c0c4-476e-a430-3f120d8e96e5","http://resolver.tudelft.nl/uuid:9f02d12a-c0c4-476e-a430-3f120d8e96e5","Coastal Protection and Dune Management in the Netherlands","Verhagen, H.J.","","1990","Because dunes protect a large part of The Netherlands against coastal flooding and inundation, it is vital to guarantee the strength of these natural sea defenses. Besides sea defense, dunes have other functions. Sandy shorelines and dunes are frequently eroded. A legal framework has been developed that guarantees the required safety-level of dunes and protects the dune environment as well. Erosion of the coastline is compensated by artificial beach nourishment.","dunes; sea defense; artificial beach nourishment; floodplain; dike; erosion","en","journal article","CERF - Coastal Education and Research Foundation","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:14d73a06-d375-4f97-9f5d-a91f8cd7cd9c","http://resolver.tudelft.nl/uuid:14d73a06-d375-4f97-9f5d-a91f8cd7cd9c","Sea defence and flood protection in the Netherlands anticipating increased sea-level rise","Verhagen, H.J.","","1990","The 1400 km Dutch coastline is affected by sea-level rise. At this moment a legal framework is made to guarantee safety of the dikes also in future. Also a national policy is developed for compensation of all coastal erosion. Both measures should make it possible for the Netherlands to survive an increased sea-level rise.","dunes; sea defence; dikes; sea level rise; coastal policy","en","conference paper","CERF -Coastal education and Research Foundation","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:4e523b85-edd2-411c-888b-7abcdd6434e1","http://resolver.tudelft.nl/uuid:4e523b85-edd2-411c-888b-7abcdd6434e1","Project Hitch Hiker: A feasibility study for a small telecommunication satellite","Nieuwenhuizen, M.P., ir.; Bunt, A.J.; Verhagen, S.P.; de Waart, D.; Belien, M.J.; de Heer, E.P.; Ho, B.P.; van Dijk, M.J.; van de Heuvel, E.P.; Theelen, B.J.; Nierop, G.V.; Shawalli, D.; Smith, A.J.; van Drimmelen, R.; Dubbeldam, M.; Maree, A.G.; Mensink, J.L.","","1990","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""
"uuid:f5ad28a5-5efe-428b-a2cf-b90c533bcc8f","http://resolver.tudelft.nl/uuid:f5ad28a5-5efe-428b-a2cf-b90c533bcc8f","A field experiment on beach growth in sand-dikes","Visser, P.J.; Vrijling, J.K.; Verhagen, H.J.","","1990","The set-up and results of a field experiment on sand-dike breach erosion are described, It is found that the breaching process for the 2.2 m high sand-dike is similar to that in Visser's (1988) laboratory experiments with a 0.6 m high sand-dike. Confrontation of Visser's (1988) breach erosion model with the field data shows reasonable agreement for the first stages of the breaching process. As yet the model is not applicable to the final phase of the sand-dike breach erosion. If applied then it would fairly overestimate the breach growth in this final stage.","breaching; dikes; erosion","en","conference paper","American Society for Civil Engineers ASCE","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:db237aab-7f9f-4da1-8092-3b7cdee9a170","http://resolver.tudelft.nl/uuid:db237aab-7f9f-4da1-8092-3b7cdee9a170","Sand Waves along the Dutch Coast","Verhagen, H.J.","","1989","Sand waves, defined as longshore wave-like movements of the shoreline, measured in a horizontal plane, are described along several stretches of the shoreline of The Netherlands. They have a celerity in the order of 50-200 m/yr, a period of 50- 150 years and an amplitude of 30- 500 m. They are found along the whole Dutch shoreline. Analysis of sand waves shows that the assumed effect of groins might be very small along this shoreline. There are indications that groins did not have any long-term effect on coastal regression.","sand wave; Coastal Morphology; oscillation; dune coast","en","journal article","Elsevier","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:7df06d48-1b6e-4fa9-b693-92f157cb8047","http://resolver.tudelft.nl/uuid:7df06d48-1b6e-4fa9-b693-92f157cb8047","Safety against inundation: The dutch approach","Verhagen, H.J.; Volker, W.F.","","1989","The most urbanized part of the Netherlands is situated below sea level and is protected by dikes. By act of parliament allowable inundation frequencies for each part of the country are fixed. In case of two dangers (river run-off and storm surge) it is a problem to determine design values for dikes. Guidelines are developed to solve these problems. Because economical , social and cultural problems with the dike improvement program, design heights of dikes have to be determined very accurately. To overcome many problems, it has been decided to build a storm surge barrier of 380 m navigation and a threshold depth of 17 m below sea level in the navigation fairway to the port of Rotterdam.","safety; flooding; sea dikes; inundation","en","conference paper","ASCE","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:0d69071b-2c70-4949-99b1-33b4bf34cbbd","http://resolver.tudelft.nl/uuid:0d69071b-2c70-4949-99b1-33b4bf34cbbd","Zandgolven en strandhoofden","Verhagen, H.J.","","1988","De effectiviteit van strandhoofden in het licht van recente resultaten van zandgolfonderzoek","groynes; strandhoofden; zandgolven","nl","journal article","Otar","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:2cc6b239-c353-4481-9df5-296146bd4983","http://resolver.tudelft.nl/uuid:2cc6b239-c353-4481-9df5-296146bd4983","Zandgolven en kustverdediging in Zeeland: Voorspelling van kustgedrag","Verhagen, H.J.; Maranus, J.W.","","1987","Langs de Zeeuwse kust bewegen grote massa's zand van zuid naar noord. Deze zandgolven zorgen voor een cyclisch kustgedrag. Bij de besluitvorming over kustverdedigingswerken en strandsuppleties is inzicht in de kinematica van deze golven essentieel.","beach nourishment; sand waves; zandgolven","nl","journal article","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:e5a4a60a-669a-4801-af2f-e7a2c75fd691","http://resolver.tudelft.nl/uuid:e5a4a60a-669a-4801-af2f-e7a2c75fd691","Rijkswaterstaat, Expertsysteem Nehalennia (Hfst 6.10)","Verhagen, H.J.","","1987","Het gebruik van kennissystemen (expersystemen) bij de beoordeling van taludstabililteit en bestortingen in Zeeland","expertsysteem","nl","book chapter","Samson","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:2eb4977b-2b1f-4afe-aeed-1528a94a99a6","http://resolver.tudelft.nl/uuid:2eb4977b-2b1f-4afe-aeed-1528a94a99a6","Geconcentreerde golfaanval: Veiligheid Oosterscheldedijken","Verhagen, H.J.","","1985","Dit artikel behandelt het deelonderzoek naar de sterkte van de glooiingen van de Oosterscheldediiken onder invloed van geconcentreerde golfaanval. ln dit artikel wordt naast de vastelling van een aantal parameters, met name de vaststelling van het berwijkmodel van een glooiing belicht. De geconcentreerde aanval (lange tijd op een vast niveau) is hierbij een belangrijk aspekt.","revetment; Oosterschelde; dijkbekleding; duurbelasting","nl","journal article","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:6a4dce42-2c08-48d5-98a8-b249eb6bf3c1","http://resolver.tudelft.nl/uuid:6a4dce42-2c08-48d5-98a8-b249eb6bf3c1","Man-made Islands in the Mackenzie river: Numerical modelling of ice jam development and release","Loman, G.J.A.; De Jong, J.J.A.; Moir, J.R.; Burgers, A.; Verhagen, H.J.","","1983","Man-made islands in the Mackenzie river (Canada) for oil exploitation may obstruct the free flow of ice during spring break up. These ice dams may cause considerable rise of the water level in the rivers, resulting in floods. A numerical model is presented to simulate ice dam formation an river floods.","ice dam; river flooding; Canada; artificial island","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:87685573-6590-4472-bbce-ea7ec18146c9","http://resolver.tudelft.nl/uuid:87685573-6590-4472-bbce-ea7ec18146c9","Coastal Changes due to the Construction of Artificial Harbour Entrances and Practical Solutions, including Beach Replenishment","Bijker, E.W.; Van der Leijé, J.P.; Pilon, J.J.; Svasek, J.N.; In 't Veld, J.K.; Verhagen, H.J.","","1981","When longshore sediment transport is interrupted by a construction along a coast, e.g harbour moles or a dredged approach channel, the equilibrium of the coastline may be disturbed. When the disruption is caused by breakwaters, the longshore transport that is held back will cause accretion updrift of the breakwaters and erosion downdrift of them. The updrift accretion may eventually result in the harbour entrance shoaling. The downdrift erosion might cause difficulties when valuable areas are situated close to the coastline or when the coastline forms a coastal protection for land behind it. When the disruption is (caused by a dredged channel, no accretion updrift of the channel will occur since the material is trapped in the channel. This means, however, that here too there is a lack of material downdrift and erosion will again occur there.","artificial island; beach nourishment; coastal morphology","en","conference paper","Pergamon - PIANC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:525da0fd-09ba-40f2-88c6-22faf17ae4b7","http://resolver.tudelft.nl/uuid:525da0fd-09ba-40f2-88c6-22faf17ae4b7","Cross-swell","Luidikhuize, D.; Verhagen, H.J.","","1981","Laboratory measurements and theoretical derivation of the resulting wave field caused by two incoming regular wave wave fields with the same period, but different direction. Test were performed in the wave basin of Delft University of Technology","swell; cross swell; regular waves; wave interaction","en","report","","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:3421a4e8-e2dd-4447-8c4d-4290be8601dc","http://resolver.tudelft.nl/uuid:3421a4e8-e2dd-4447-8c4d-4290be8601dc","Van monodisciplinaire opdracht tot multidisciplinaire werkelijkheid","Verhagen, C.J.D.M.","","1980","","Uittreerede","nl","public lecture","DUP","","","","","","","","","","","","",""
"uuid:4d4f026d-3ac7-4167-83c8-03ff1aef4a0c","http://resolver.tudelft.nl/uuid:4d4f026d-3ac7-4167-83c8-03ff1aef4a0c","Tentamenhandleiding constructieleer","Verhagen, H.J.","","1972","Uitgewerkte (teken) opdrachten voor het vak constructieleer I.","constructieleer; collegediktaat","nl","lecture notes","Jaarcommissie Practische Studie","","","","","","","","Civil Engineering and Geosciences","","","","",""
"uuid:ce6c2605-b1a0-48c5-bfe7-8b3a2275940e","http://resolver.tudelft.nl/uuid:ce6c2605-b1a0-48c5-bfe7-8b3a2275940e","Rectorale rede","Verhagen, C.J.D.M.","","1970","","Opening academisch jaar","nl","public lecture","","","","","","","","","","","","","",""
"uuid:676f1f3a-edcc-4cbf-8307-5292809ae022","http://resolver.tudelft.nl/uuid:676f1f3a-edcc-4cbf-8307-5292809ae022","Rectorale rede","Verhagen, C.J.D.M.","","1969","","Rede opening academisch jaar 1969-1970","nl","public lecture","Technische Hogeschool Delft","","","","","","","","","","","","",""
"uuid:ddcb00d6-1198-450e-9cd9-c56b8e2cea98","http://resolver.tudelft.nl/uuid:ddcb00d6-1198-450e-9cd9-c56b8e2cea98","Rectorale rede","Verhagen, C.J.D.M.","","1968","","Opening academisch jaar","nl","public lecture","","","","","","","","","","","","","",""
"uuid:36b15f75-832a-4719-8f3e-eb48f5747591","http://resolver.tudelft.nl/uuid:36b15f75-832a-4719-8f3e-eb48f5747591","Rekenmachines in Delft","Verhagen, C.J.D.M.","","1960","","","nl","book","Uitgave van de Commissie Rekenmachines van de Techinsche Hogeschool Delft","","","","","","","","","","","","",""
"uuid:3034846a-5631-434f-98a5-df95209b119d","http://resolver.tudelft.nl/uuid:3034846a-5631-434f-98a5-df95209b119d","Meet- en regeltechniek aan de Technische Hogeschool te Delft","Boiten, R.G.; van Nauta Lemke, HR; Verhagen, C.J.D.M.","","1960","","","nl","report","T.H. Mededelingen","","","","","","","","","","","","",""
"uuid:88f29a0b-5699-407e-a82e-ee50914717ed","http://resolver.tudelft.nl/uuid:88f29a0b-5699-407e-a82e-ee50914717ed","Zinkwerken Schouwen-Duiveland watersnood 1953 - Fotoalbum; Fotoalbum","Verhagen, H.J.","","1954","","watersnoodramp 1953; Zeeland","nl","report","Aannemers- en handelsbedrijf van Oord Werkendam","","","","","","","","","","","","",""
"uuid:87f4737d-e696-4c32-bf34-b4376eda2952","http://resolver.tudelft.nl/uuid:87f4737d-e696-4c32-bf34-b4376eda2952","Caissons voor het dichten van dijken in Zeeland 1953; Fotoalbum","Verhagen, H.J.","","1953","Foto's van caissons voor het dichten van dijken in Zeeland in 1953. Geleverd werden 493 caissons en 203 manchetten door een combinatie van: N.V. Amsterdamsche Ballast maatschappij, Amsterdam Christiani en Nielsen N.V., ’s Gravenhage N.V. van Hattum en Blankevoort, Beverwijk Hollandsche Beton Maatschappij, ’s Gravenhage N.V. Internationale Gewapend Beton Bouw, Breda N.V. Nederlandsche Aanneming Maatschappij, ’s Gravenhage N.V. Nederlandsche Beton Maatschappij Bato, ’s Gravenhage 4. Bouwplaats Merwehaven Rotterdam, Noordelijk gedeelte, met traversen Foto Tom Kroeze 5. Bouwplaats Merwehaven Rotterdam, Zuidelijk gedeelte, met torenkraan Foto Tom Kroeze 6. Bouwplaats Merwehaven Rotterdam, stellen van wabpeningsstaal Foto Tom Kroeze 7. Bouwplaats Merwehaven Rotterdam, stellen van bekisting Foto Tom Kroeze 8. Bouwplaats Merwehaven Rotterdam, betonstorten Foto Tom Kroeze 9. Bouwplaats Merwehaven Rotterdam, stellen van bekisting Foto Tom Kroeze 10. Bouwplaats Waalhaven Rotterdam met portaalkraan, torenkraan en Befaro-auto Foto Klaver 11. Bouwplaats Keizersveer, manchetten in aanbouw Foto van Gils 12. Bouwplaats Keizersveer, betonstorten Foto van Gils 13. Bouwplaats Keizersveer, vervoer van een manchet Foto van Gils 14. Bouwplaats Coenhaven Amsterdam, overzicht Foto ir. A.V. Klein 15. Bouwplaats Coenhaven Amsterdam, overzicht Foto ir. A.V. Klein 16. Bouwplaats Coenhaven Amsterdam, tewaterlating en vervoer Foto ir. A.V. Klein 17. Bouwplaats Coenhaven Amsterdam, tewaterlating en vervoer Foto ir. A.V. Klein 18. Bouwplaats Coenhaven Amsterdam, tewaterlating en vervoer Foto ir. A.V. Klein 19. Een der opslagplaatsen Waalhaven Rotterdam Foto Ton Kroeze 20. Assemblage van een sluitgatcaisson, Merwehaven Rotterdam Foto Ton Kroeze 21. Assemblage van een sluitgatcaisson, Merwehaven Rotterdam Foto Ton Kroeze 22. Assemblage van een sluitgatcaisson, Merwehaven Rotterdam Foto Ton Kroeze 23. Een sluitgatcaisson vaart naar Zeeland Foto Ton Kroeze 24. Assemblage. Op de wal een na beschadiging gerepareerde caisson, Waalhaven Rotterdam Foto Klaver 25. Sluiting bij Zierikzee 4-6-1953 Foto KLM 26. Sluiting bij Kruiningen 4-6-1953 Foto KLM 27. Sluiting bij Kruiningen 4-6-1953 Foto KLM 28. Landhoofden bij Kruiningen Foto Stuvel 29. Sluiting bij Stevenssluis. Overzicht 28-7-1953 Foto KLM 30. Sluiting bij Stevenssluis. De deur is nog open Foto Stuvel 31. Sluiting bij Stevenssluis. De caisson is geplaatst en wordt volgespoten Foto Stuvel 32. Sluiting bij Ouwerkerk, Westelijk gat Foto A.N.P. 33. Een stevige betonconstructie is bestand tegen een willekeurige manier van neerleggen Foto Stuvel 34. Overzicht Schelphoek 26-8-1953 Foto KLM 35. Sluiting Gemene Geul Schelphoek 20-8-1953 Foto KLM 36. Maaiveldsluiting Schelphoek 26-8-1953 Foto KLM 37. Maaiveldsluiting Schelphoek met dorp Serooskerke Foto A.N.P. 38. Overzicht sluiting Ouwerkerk 7-11-1953 Foto KLM 39. Ouwerkerk gesloten. De dijken zijn dicht 7-11-1953 Foto KLM","watersnoodramp 1953; Zeeland","nl","report","","","","","","","","","","","","","",""
"uuid:950dc743-18eb-461f-a95b-85e4cb5b9076","http://resolver.tudelft.nl/uuid:950dc743-18eb-461f-a95b-85e4cb5b9076","Theorie en metingen over de impedantie en de stabiliteit van gasontladingen","Verhagen, C.J.D.M.","Dorgelo, H.B. (promotor)","1942","","","nl","doctoral thesis","","","","","","","","","Applied Sciences","","","","",""
"uuid:d9cc5c15-b061-4ff0-a7fd-fcc3ed61a143","http://resolver.tudelft.nl/uuid:d9cc5c15-b061-4ff0-a7fd-fcc3ed61a143","De sluizen bij Lith; Fotoalbum","Verhagen, H.J.","","1936","Foto’s van het sluiscomplex tijdens het inhangen van de stuwen, een foto van de motor voor het heffen van de stuw en een gezelschap in de omgeving van de sluis.","waterwerken; sluizen; Lith","nl","report","","","","","","","","","","","","","",""
"uuid:626e218e-2544-4e7d-bd18-4f122a5a7428","http://resolver.tudelft.nl/uuid:626e218e-2544-4e7d-bd18-4f122a5a7428","Aanleg sluizencomplex te Lith; Fotoalbum","Verhagen, H.J.","","1936","Serie foto’s van de KLM tijdens de aanleg van het sluis- en stuwcomplex en de bijbehorende bochtafsnijdingen in de Maas. Detailopnamen van de de stuw. De stuw is aangelegd in de periode 1932-1936.","waterwerken; sluizen; Lith","nl","report","","","","","","","","","","","","","",""
"uuid:35866d58-571a-4522-ac11-6988ebc26700","http://resolver.tudelft.nl/uuid:35866d58-571a-4522-ac11-6988ebc26700","Aanleg stuw- en sluizencomplex te Lith: Laatste fase van de bouw van het betonwerk, bodembescherming en de bewegingswerken. De stuw is aangelegd in de periode 1932-1936 Gedeeltelijk als werkverschaffingsproject; Fotoalbum","Verhagen, H.J.","","1936","Fotorapportage van de aanleg stuw- en sluizencomplex te Lith. Laatste fase van de bouw van het betonwerk, bodembescherming en de bewegingswerken: De stuw is aangelegd in de periode 1932-1936 Gedeeltelijk als werkverschaffingsproject. 3. Noordelijk landhoofd 4. Aansluiting van zinkstuk aan stortebed 5. Ontgraving bouwput 8-10-‘32 6. Ontgraving bouwput 7. Ontgraving bouwput 4-10-‘32 8. Stortebed 9. Détail aansuiting sponningstuwvloer 10. Vischtrap 11. Drempel 12. Doorgraving nieuwe rivier 13. Overzicht stuwcomplex juni 1937 14. Stuw in bedrijf 15. Stuw in bedrijf 16. Bekistingwerken pijlers 17. Taludbekleding Noordelijk landhoofd 18. Storten van betontalud 19. Uitmonding vishctrap – betontalud - gedeelte stortebed 20. Doorgraving nieuwe rivier 21. Pijler 22. Afwerken pijlers en landhoofden 23. Het stellen van de gelijdingrails 24. Uitmonding vischtrap Zuidelijk landhoofd 25. Ontvangbed 26. Bewegingswerkstuk 27. Inhangen van de stuw 28. Inhangen van de stuw 29. Inhangen van de stuw 30. Inhangen van de stuw 31. Stuw op de werf 32. katrol van de bok","waterwerken; sluizen; Lith","en","report","","","","","","","","","","","","","",""
"uuid:fd9ff97c-0a3c-4183-818d-fcf7999ab8e9","http://resolver.tudelft.nl/uuid:fd9ff97c-0a3c-4183-818d-fcf7999ab8e9","Dijk- en oeverval aan den cal. Willem Annapolder (Gem. Kapelle); Fotoalbum","Verhagen, H.J.","","1936","Foto's van de aanleg van de dijk- en oeverval aan den cal. Willem Annapolder (Gem. Kapelle) 3. Linkerhelft dijkval Willem Annapolder. 30 Dec. 1936 4. Rechtehelft dijkval Willem Annapolder. 30 Dec. 1936 5. Overzicht dijkval Willem Annaolder. 30 Dec. 1936 6. Kleikisting binnendijks aangebacht. 14/15 Dec. 1936 7. Voorbereiding voor het maaken van een zinkstuk groot 2000 M2. 30 Dec. 1936 8. Voltooiing van het zinkstuk groot 2000 M2. met motorschip en rijsklamp. 30 Dec. 1936 9. Overzichtsfoto wiepenstelling en zinkstuk. 30 Dec. 1936 10. Volksverblijf met uitvoerder en dagelijks opzichter. 30 Dec. 1936 11. Zolderbakken met stortsteen in lossing voor den dijkval. 2 Jan. 1937 12. Het zinkstuk is bijna gereed om gezonken te worden. 2 Jan. 1937 13. Het moment van het loslaten der zinklijnen van het zinkstuk groot 2000 M2. 2 Jan. 1937 14. De nabestorting van het zinkstuk wordt aangebracht. 2 Jan. 1937","waterwerken; Zeeland","nl","report","Jan Roskam Czn. Sliedrecht","","","","","","","","","","","","",""
"uuid:994e4158-44e3-4c96-be3c-1457d164b59e","http://resolver.tudelft.nl/uuid:994e4158-44e3-4c96-be3c-1457d164b59e","Stuw te Lith: Fabricage van de stuwschuiven: 1935","Verhagen, H.J.","","1935","Foto's van de fabricage van de stuwschuiven van de stuw bij Lith in 1935","waterwerken; sluizen; Lith","nl","report","","","","","","","","","","","","","",""