"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:d282e08e-6348-434b-b9c8-f3436b727341","http://resolver.tudelft.nl/uuid:d282e08e-6348-434b-b9c8-f3436b727341","Reviews and responses for Compilation of an open-source traffic and CO2 emissions dataset for commercial aviation","Salgas, A. (Université de Toulouse); Sun, Junzi (TU Delft Control & Simulation); Delbecq, Scott (Université de Toulouse); Planès, Thomas (Université de Toulouse); Lafforgue, Gilles (Université de Toulouse)","Catarino Soares Franco, A.M. (editor); Li, Max (editor); Strohmeier, Martin (editor)","2024","","Open-data; Emissions; Air Traffic","en","contribution to periodical","","","","","","","","","","","Control & Simulation","","",""
"uuid:806323be-e2aa-4bc6-86b1-ca2df873d75f","http://resolver.tudelft.nl/uuid:806323be-e2aa-4bc6-86b1-ca2df873d75f","Fast contrail estimation with OpenSky data","Sun, Junzi (TU Delft Control & Simulation); Roosenbrand, E.J. (TU Delft Control & Simulation)","","2024","Contrails, formed under specific atmospheric conditions, have a noteworthy role in heat-trapping within the atmosphere. This study bridges the gap between theoretical contrail formation models and real-world data by employing flight information from OpenSky and meteorological data from the European Centre for Medium-Range Weather Forecasts. We introduce a computationally efficient contrail estimation module, leveraging a client-server architecture that allows on-demand weather data interpolation via an API, significantly reducing computational load and enhancing performance locally. The study also benchmarks the entire pipeline, from data acquisition to contrail prediction, offering a robust tool for future air traffic studies requiring interpolated weather data.","Open-data; Emissions; Air Traffic","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:f6290571-fabb-4857-910a-4fb4300b1c54","http://resolver.tudelft.nl/uuid:f6290571-fabb-4857-910a-4fb4300b1c54","Reviews and responses for Fast contrail estimation with OpenSky data","Sun, Junzi (TU Delft Control & Simulation); Roosenbrand, E.J. (TU Delft Control & Simulation)","Figuet, Benoit (editor); Dubot, Thomas (editor); Waltert, Manuel (editor); Olive, Xavier (editor)","2024","Contrails, formed under specific atmospheric conditions, have a noteworthy role in heat-trapping within the atmosphere. This study bridges the gap between theoretical contrail formation models and real-world data by employing flight information from OpenSky and meteorological data from the European Centre for Medium-Range Weather Forecasts. We introduce a computationally efficient contrail estimation module, leveraging a client-server architecture that allows on-demand weather data interpolation via an API, significantly reducing computational load and enhancing performance locally. The study also benchmarks the entire pipeline, from data acquisition to contrail prediction, offering a robust tool for future air traffic studies requiring interpolated weather data.","Open-data; Emissions; Air Traffic","en","contribution to periodical","","","","","","","","","","","Control & Simulation","","",""
"uuid:a024a3ff-7f37-4eb1-aaae-e71a3955ebc9","http://resolver.tudelft.nl/uuid:a024a3ff-7f37-4eb1-aaae-e71a3955ebc9","Compilation of an open-source traffic and CO2 emissions dataset for commercial aviation","Salgas, A. (Université de Toulouse); Sun, Junzi (TU Delft Control & Simulation); Delbecq, Scott (Université de Toulouse); Planès, Thomas (Université de Toulouse); Lafforgue, Gilles (Université de Toulouse)","","2024","The study of the environmental transition of the aviation sector calls for prospective traffic scenarios. Detailed traffic and emissions inventories are often needed to refine the available analyses and to enable the simulation of regionalised scenarios. In the past studies, these are generally based on commercial, proprietary traffic data, making their dissemination problematic and reducing the reproducibility of the science produced. Open-source alternatives do exist, but with limited geographical coverage. This paper presents a method to aggregate different sources of flight information, in order to obtain an open-source air traffic dataset for 2019. Then, missing flight information is identified and completed using an airline route database built from Wikipedia parsing and related socio-economic data. After that, several reference datasets are used to evaluate the accuracy of the extended open-source dataset. Despite varying accuracy for different routes, major traffic flows are reasonably well estimated at the country and continental levels. Finally, the CO2 emissions are obtained using an existing aircraft performance surrogate model, and the accuracies are examined compared to the results from previous studies.","Open-data; Emissions; Air Traffic","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:fc625a4f-c5bc-4ba2-8a25-1663f031444a","http://resolver.tudelft.nl/uuid:fc625a4f-c5bc-4ba2-8a25-1663f031444a","Identification and Suppression of Multicomponent Noise in Audio Magnetotelluric Data Based on Convolutional Block Attention Module","Zhang, Liang (Guizhou University); Li, Guang (East China University of Technology); Chen, Huang (Chongqing University); Tang, Jingtian (Central South University); Yang, Guanci (Guizhou University); Yu, Mingbiao (Guizhou University); Hu, Yong (China University of Mining and Technology; China University of Petroleum (East China)); Xu, Jun (Guizhou University); Sun, J. (TU Delft Pattern Recognition and Bioinformatics)","","2024","Audio magnetotelluric (AMT) is commonly used in mineral resource exploration. However, the weak energy of AMT signals makes them susceptible to being overwhelmed by noise, leading to erroneous geophysical interpretations. In recent years, deep learning has been applied to AMT denoising and has shown better denoising performance compared to traditional methods. However, current deep learning denoising methods overlook the characteristics of AMT signals, resulting in reduced denoising accuracy. To enhance the denoising performance of deep learning by better matching the features of AMT signals, we propose a convolutional block attention module (CBAM)-based method for AMT denoising. This method focuses on the features of AMT signals and improves the process from three aspects: 1) in the establishment of the sample set, we adopt a multicomponent form based on the correlation of noise to enable the neural network to explore the potential connections among the components of AMT during the training process, thus constructing a stronger network mapping relationship; 2) in the construction of the neural network, we have introduced the CBAM structure into the residual blocks of the ResNet to enhance the network's feature learning capability by focusing on the characteristics of noise; and 3) in the design of the denoising procedure, we adopt a process of identification before denoising to protect the noise-free data segments from being compromised during the denoising process. Finally, through synthetic, field data experiments, and comparative tests, we demonstrate that our proposed method achieves higher denoising accuracy than some traditional methods and conventional deep learning methods.","Convolutional Block Attention Module (CBAM); ResNet; Audio Magnetotelluric (AMT); Denoising","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.","","2024-08-05","","","Pattern Recognition and Bioinformatics","","",""
"uuid:3d0c1cf8-8e92-459a-8f6c-01f204cb1cdf","http://resolver.tudelft.nl/uuid:3d0c1cf8-8e92-459a-8f6c-01f204cb1cdf","Enzyme engineering for biocatalysis","Paul, C.E. (TU Delft BT/Biocatalysis); Hanefeld, U. (TU Delft BT/Biocatalysis); Hollmann, F. (TU Delft BT/Biocatalysis); Qu, Ge (Chinese Academy of Sciences); Yuan, Bo (Chinese Academy of Sciences); Sun, Zhoutong (Chinese Academy of Sciences)","","2024","Contemporary Biocatalysis heavily relies on enzyme engineering as natural enzymes frequently lack the requisite attributes for effective organic synthesis. The inherent limitations in stability, catalytic activity, and selectivity of wild-type enzymes often hinder their suitability for chemical synthesis. Over the past 25 years, there has been an unprecedented advancement in protein engineering tools, empowering enzymologists to customise enzymes to precisely meet the demands of organic synthesis. In this discussion, we delineate some of the most crucial techniques in enzyme engineering and their significance in facilitating chemical synthesis.","Biocatalysis; Directed evolution; Iterative saturation mutagenesis; Semi-rational design","en","journal article","","","","","","","","","","","BT/Biocatalysis","","",""
"uuid:640c0f3e-60c4-4736-ae08-352bef953637","http://resolver.tudelft.nl/uuid:640c0f3e-60c4-4736-ae08-352bef953637","On the post-impact fatigue behavior and theoretical life prediction of CF/PEEK-titanium hybrid laminates using an energy dissipation approach","Ji, C. (TU Delft Structural Integrity & Composites; Harbin Institute of Technology); Hu, Jiqiang (Harbin Institute of Technology); Alderliesten, R.C. (TU Delft Structural Integrity & Composites); Yang, Jinchuan (Harbin Institute of Technology); Zhou, Zhengong (Harbin Institute of Technology); Sun, Yuguo (Harbin Institute of Technology); Wang, Bing (Harbin Institute of Technology)","","2024","This paper aims to illustrate the effect of the impact damage on fatigue behavior of CF/PEEK-titanium hybrid laminates. To achieve this end, a fatigue life model was proposed to predict the S–N curves of the laminates at various initial impact energy levels and stress ratios based on the energy dissipation approach. The energy dissipation behavior of the laminates during fatigue loading under different experimental conditions was analyzed through a large amount of post-impact fatigue tests, and the correlation between the initial impact damage and the total fatigue dissipation energy was determined. The full-field axial strain distribution of the titanium layer on the impacted side of the laminate was characterized in terms of initial impact energy level and maximum stress using digital image correlation, and then the post-impact fatigue failure mechanism of CF/PEEK-Ti hybrid laminates was summarized. Finally, the validity of the proposed model was verified by fatigue tests under other conditions of stress ratio and impact energy level. It is worth mentioning that the proposed model is also applicable to other types of FMLs, and can accurately predict the residual fatigue life of laminates after impact with only one set of S–N curve data.","Energy dissipation approach; Fiber metal laminates; Life prediction; Post-impact fatigue behavior","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.","","2024-06-03","","","Structural Integrity & Composites","","",""
"uuid:740ae19e-044a-4bb1-80c8-0c3da244b184","http://resolver.tudelft.nl/uuid:740ae19e-044a-4bb1-80c8-0c3da244b184","Dynamic risk assessment of chemical process systems using the System-Theoretic accident model and process approach (STAMP) in combination with cascading failure propagation model (CFPM)","Sun, Hao (Anhui University of Technology); Wang, Haiqing (China University of Petroleum (East China)); Yang, M. (TU Delft Safety and Security Science; Universiti Teknologi Malaysia); Reniers, G.L.L.M.E. (TU Delft Safety and Security Science; Universiteit Antwerpen; Katholieke Universiteit Leuven)","","2024","To maintain continuous production, chemical plant operators may ignore faults or handle faults online rather than shutting down process systems. However, interaction and interdependence links between components in a digitalized process system are substantial. Thus, faults will be propagated to downstream nodes, potentially leading to risk accumulation and major accidents. However, limited attention has been paid to this type of risk. To model the risk accumulation process, a dynamic risk assessment method is proposed by integrating the system-theoretic accident model and process approach (STAMP) and the cascading failure propagation model (CFPM). Firstly, STAMP is used to model and analyze the system safety of a process system. Two CFPMs are then proposed to measure risk accumulation under two different engineering situations. The proposed method is applied to the Chevron Richmond refinery crude unit and its associated upstream process. The results show that the proposed approach can effectively quantify the process of risk accumulation. This method can generate a real-time dynamic risk profile to support auxiliary decision-making.","Cascading failure propagation model (CFPM); Fault propagation; Risk accumulation; STAMP","en","journal article","","","","","","","","","","","Safety and Security Science","","",""
"uuid:39016597-6bf1-4636-89c2-96cf9cf1707e","http://resolver.tudelft.nl/uuid:39016597-6bf1-4636-89c2-96cf9cf1707e","An integrated approach to quantitative resilience assessment in process systems","Sun, H. (TU Delft Safety and Security Science; Anhui University of Technology; China University of Petroleum (East China)); Yang, M. (TU Delft Safety and Security Science); Wang, Haiqing (China University of Petroleum (East China))","","2024","Chemical process systems are becoming more automated and complex, which leads to increased interaction and interdependence between the human and technical elements of process systems. This urges the need for updating the safety assessment method by treating “safety” as an emergent property of a system. Uncertainty comes together with complexity. To enhance system ability of dealing with uncertain disruptions, this paper proposes a quantitative resilience assessment method by modeling the failure propagation (initiated by a disruption) across the functional units of a system. The Functional Resonance Analysis Method (FRAM) is utilized to model the system operation to represent the relationship among its function units and to consider the interactions among human-technical factors. Then, a Cascading Failure Propagation Model (CFPM) is developed to quantify the fault propagation process and reflect the system functionality changes over time for resilience assessment. The proposed method is applied to a propane-feeding control system. The results show that it can help practitioners understand the process of fault propagation and risk increase, identify potential ways to design a more resilient system to respond to uncertain disruptions/attacks, and provide a real-time dynamic resilience profile to support decision-making.","Human-technical systems, FRAM, resilience; Process safety","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.","","2024-06-13","","","Safety and Security Science","","",""
"uuid:b2ef9acd-9738-431d-a368-a0069ddf756d","http://resolver.tudelft.nl/uuid:b2ef9acd-9738-431d-a368-a0069ddf756d","Sediment fluxes within salt marsh tidal creek systems in the Yangtze Estuary","Sun, J. (TU Delft Coastal Engineering; East China Normal University); van Prooijen, Bram (TU Delft Coastal Engineering); Wang, Xianye (East China Normal University); Zhao, Zhonghao (East China Normal University); He, Qing (East China Normal University); Wang, Zhengbing (TU Delft Coastal Engineering; Deltares)","","2024","Creeks are essential for salt marshes by conveying water and sediment through this geomorphic system. In this paper, we investigate the mechanisms that determine the residual sediment flux using measurements conducted in tidal creeks in salt marshes of the Yangtze Estuary. A main creek and a secondary creek were studied to explore whether the mechanisms determining residual sediment fluxes through the main creek differ from those in the secondary creek. Measurements in creeks were carried out over 5 years, spanning different months. Sediment import was found during most tides, both in the main creek and the secondary creek, implying that creeks in Chongming generally function as a conveyor belt of sediment into the marsh. However, sediment export can occur during certain overbank tides. When comparing the role of creeks in drainage and sediment delivery, the main creek functions more in delivering sediment while the secondary creek primarily serves as a drainage conduit. To better understand the mechanisms behind sediment fluxes, the residual sediment flux was compared with the residual discharge and the sediment differential (differences in sediment concentration between flood and ebb). Overbank tides generally lead to a net outward discharge as more water from saltmarshes can be concentrated into the marsh creek during ebb tides. This net outward discharge tends to export more sediment during ebb tides. However, due to the sediment abundance during the flood phase in the turbid environment, sediment import can be expected even with the residual export of water. Export of sediment was only found for the few tides with a net outward discharge and a small positive sediment concentration differential. Large negative sediment differentials (larger averaged suspended sediment concentration during ebb tides) have not been observed because the sediment supply during ebb is limited. This paper unravels how the sediment differential and residual discharge contribute to the residual sediment flux, providing a better understanding of sediment dynamics in marsh creek systems.","Marsh creek systems; Sediment availability; Sediment flux","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.","","2024-07-04","","","Coastal Engineering","","",""
"uuid:e7444ac1-5c3b-4901-a940-986f3962debb","http://resolver.tudelft.nl/uuid:e7444ac1-5c3b-4901-a940-986f3962debb","A study on siting of emergency shelters for dam failure floods considering population distribution and weather effects","Jiao, Yutie (Zhengzhou University); Li, Zongkun (Zhengzhou University); Ge, Wei (Zhengzhou University; Yellow River Engineering Consulting Co); Jing, Laihong (Yellow River Engineering Consulting Co); Wu, Meimei (Henan University of Technology, Zhengzhou); Wang, Te (Zhengzhou University); Sun, Heqiang (Zhengzhou University); Wang, Jianyou (Zhengzhou University); Zhang, Xiangyang (Zhengzhou University); van Gelder, P.H.A.J.M. (TU Delft Safety and Security Science)","","2024","In recent years, dam failures have occurred frequently because of extreme weather, posing a significant threat to downstream residents. The establishment of emergency shelters is crucial for reducing casualties. The selection of suitable shelters depends on key information such as the number and distribution of affected people, and the effective capacity and accessibility of the shelters. However, previous studies on siting shelters did not fully consider population distribution differences at a finer scale. This limitation hinders the accuracy of estimating the number of affected people. In addition, most studies ignored the impact of extreme rainfall on the effective capacity and accessibility of shelters, leading to a low applicability of the shelter selection results. Therefore, in this study, land-use and land-cover change (LUCC) and nighttime lighting data were used to simulate population distribution and determine the number and distribution of affected people. Qualified candidate shelters were obtained based on screening criteria, and their effective capacity and accessibility information under different weather conditions were quantified. Considering factors such as population transfer efficiency, construction cost and shelter capacity constraints, a multi-objective siting model was established and solved using the non-dominated sorting genetic algorithm II (NSGA- II) to obtain the final siting scheme. The method was applied to the Dafangying Reservoir, and the results showed the following: (1) The overall mean relative error (MRE) of the population in the 35 downstream streets was 11.16 %, with good fitting accuracy. The simulation results truly reflect the population distribution. (2) Normal weather screening generated 352 qualified candidate shelters, whereas extreme rainfall weather screening generated 266 candidate shelters. (3) Based on the population distribution and weather factors, four scenarios were set up, with 63, 106, 73, and 131 shelters selected. These two factors have a significant impact on the selection of shelters and the allocation of evacuees, and should be considered in the event of a dam-failure floods.","Dam-failure floods; Emergency transfer; Population distribution; Shelters selection; Weather factors","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.","","2024-07-05","","","Safety and Security Science","","",""
"uuid:a29c1fb2-05f7-4560-a053-9e02163a7560","http://resolver.tudelft.nl/uuid:a29c1fb2-05f7-4560-a053-9e02163a7560","Release of phosphorus through pretreatment of waste activated sludge differs essentially from that of carbon and nitrogen resources: Comparative analysis across four wastewater treatment facilities","Deng, Shaoyu (Beijing Forestry University); Liu, J. (Beijing Forestry University); Yang, Xiaofan (Beijing Forestry University); Sun, Dezhi (Beijing Forestry University); Wang, Aijie (Harbin Institute of Technology); van Loosdrecht, Mark C.M. (TU Delft BT/Environmental Biotechnology); Cheng, Xiang (Beijing Forestry University)","","2024","The accumulation of phosphorus in activated sludge in wastewater treatment plants (WWTPs) provides potential for phosphorus recovery from sewage. This study delves into the potential for releasing phosphorus from waste activated sludge through two distinct treatment methods—thermal hydrolysis and pH adjustment. The investigation was conducted with activated sludge sourced from four WWTPs, each employing distinct phosphorus removal strategies. The findings underscore the notably superior efficacy of pH adjustment in solubilizing sludge phosphorus compared to the prevailing practice of thermal hydrolysis, widely adopted to enhance sludge digestion. The reversibility of phosphorus release within pH fluctuations spanning 2 to 12 implies that the release of sludge phosphorus can be attributed to the dissolution of phosphate precipitates. Alkaline sludge treatment induced the concurrent liberation of COD, nitrogen, and phosphorus through alkaline hydrolysis of sludge biomass and the dissolution of iron or aluminium phosphates, offering potential gains in resource recovery and energy efficiency.","Activated sludge; Alkaline treatment; Resource recovery; Thermal hydrolysis","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.","","2024-08-09","","","BT/Environmental Biotechnology","","",""
"uuid:b0950925-9d33-40a6-8d5d-8b2dc1e060a2","http://resolver.tudelft.nl/uuid:b0950925-9d33-40a6-8d5d-8b2dc1e060a2","Comparison of Compact and Decentralized Urban Development Pathways for Flood Mitigation in Urbanizing Deltas: Guangzhou in the Pearl River Delta as a Case Study","Lin, Weibin (Central South University); Sun, Yimin (Central South University); Nijhuis, S. (TU Delft Landscape Architecture)","","2024","Floods are common and inevitable natural disasters. Achieve Sustainable Development Goal (SDG) 11.5 is a critical challenge for coastal cities, especially those in deltaic lowlands such as in the case of Guangzhou, China. Regarding the spatial planning and design of such urban regions, it is crucial to study the impacts of flooding in compact or decentralized spatial development pathways. This reinforces the understanding of the relationship between strategic decisions for spatial planning and flood mitigation. However, the lack of a computer model to assess spatial evolution paths is a significant limitation. The non-dominated Sorting Genetic Algorithm II (NSGA-II) explores the possibility of a compact built-up land layout in 2030. The results showed that, concerning the 2030 decentralized scenario, the 2030 compact scenario presents a large increase in the integrated fitness function value from 0.618 to 0.771 (the increase is equivalent to 0.153 or about 24.75%). In addition, different development scenarios were constructed by setting different target weights. Compared to the decentralized scenario results, the fitness function values of the optimization results of each scenario showed better results at different levels. They could also serve as a reference for other similar coastal areas to achieve SDG 11.5 by 2030.","spatial evolution path; Guangzhou estuary area; multi-objective optimization; flood disaster; SDG 11.5","en","journal article","","","","","","","","","","","Landscape Architecture","","",""
"uuid:c390ab8c-1ff0-44d8-8885-a6b1e7088503","http://resolver.tudelft.nl/uuid:c390ab8c-1ff0-44d8-8885-a6b1e7088503","Characterization and mechanical removal of metallic aluminum (Al) embedded in weathered municipal solid waste incineration (MSWI) bottom ash for application as supplementary cementitious material","Chen, B. (TU Delft Materials and Environment); Chen, J. (TU Delft Materials and Environment); França de Mendonça Filho, F. (TU Delft Materials and Environment); Sun, Yubo (Universiteit Gent); van Zijl, Marc Brito (Mineralz); Copuroglu, Oguzhan (TU Delft Materials and Environment); Ye, G. (TU Delft Materials and Environment; Universiteit Gent)","","2024","Municipal solid waste incineration (MSWI) bottom ash, due to its high mineral content, presents great potential as supplementary cementitious material (SCM). Weathering, also known as aging, is a treatment process commonly employed in waste management to minimize the risk of heavy metal leaching from MSWI bottom ash. Using weathered MSWI bottom ash to produce blended cement pastes is considered as a high-value-added and sustainable waste disposal solution. However, a critical challenge arises from the metallic aluminum (Al) in weathered MSWI bottom ash, which is known to induce detrimental effects such as volume expansion and strength loss of blended cement pastes. While most metallic Al in weathered MSWI bottom ash can be removed with eddy current separators in metal recovery plants, the residual metallic Al, owing to its small particle size, cannot be removed with the same technique. This study is dedicated to addressing this issue. An in-depth analysis was conducted on residual metallic Al embedded in weathered MSWI bottom ash particles, aiming to guide the removal of this metal. This analysis revealed that mechanical removal was the most suitable method for extracting metallic Al. The specific processes and mechanisms underlying this method were elucidated. After reducing metallic Al content in weathered MSWI bottom ash by 77 %, a significant improvement in the quality of blended cement pastes was observed. This work contributes to the broader adoption of mechanical treatments for removing residual metallic Al from weathered MSWI bottom ash and facilitates the application of treated ash as SCM.","Mechanical treatments; Metallic aluminum (Al) distribution; Municipal solid waste incineration (MSWI) bottom ash; Supplementary cementitious material (SCM); Weathering","en","journal article","","","","","","","","","","","Materials and Environment","","",""
"uuid:62166ffb-ad44-4afc-aedd-234b9cd4a399","http://resolver.tudelft.nl/uuid:62166ffb-ad44-4afc-aedd-234b9cd4a399","Carbon solute drag effect on the growth of carbon supersaturated bainitic ferrite: Modeling and experimental validations","Dai, Zongbiao (Xi’an Jiaotong University); Chen, H. (TU Delft Novel Aerospace Materials; Tsinghua University); Sun, Junjie (Xi’an Jiaotong University); van der Zwaag, S. (TU Delft Group Garcia Espallargas); Sun, Jun (Xi’an Jiaotong University)","","2024","The carbon partitioning and lengthening rate of bainitic ferrite (αb) are excellent experimental parameters to estimate our level of understanding of the mechanism of bainitic transformation from a continuum perspective and our ability to capture it in analytical expressions. For Fe-C alloys and relatively simple steels the classical Zener-Hillert theory captures the bainitic transformation rather well but mispredicts the level of carbon in solution in the bainite and overestimates the lengthening rates for transformations at lower temperatures. To address this issue, this paper presents a new thermo-kinetic model based on the Zener-Hillert theory and the Gibbs energy balance concept to simulate the lengthening behavior of αb in the Fe-C and low alloyed steels. The model incorporates the effect of the temperature dependent carbon diffusion within the migrating interface via a temperature dependent ferrite/austenite interfacial energy and a temperature dependent diffusion coefficient but does not impose local equilibrium across the interface. The good agreement between the model predictions and nine sets of published experiments indicates that both the carbon supersaturation in αb and the slower lengthening rate are caused by carbon diffusion within the migrating interface. It is found that the degree of carbon supersaturation in αb increases significantly with decreasing temperature. Consequently, the enhanced carbon solute drag effect, resulting from carbon diffusion within the interface, strongly retards the lengthening rates of αb at lower temperatures. Transformation strain is shown to have a modest effect on the lengthening rates but to lower the degree of carbon supersaturation.","Bainite formation; Carbon diffusion; Carbon supersaturation; Energy dissipation; Lengthening kinetics","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.","","2024-09-02","","","Novel Aerospace Materials","","",""
"uuid:12a11b1c-a3de-4c8b-a05a-fc6790d538a5","http://resolver.tudelft.nl/uuid:12a11b1c-a3de-4c8b-a05a-fc6790d538a5","A conceptual design of two-stream alkali-activated materials","Sun, Yubo (Universiteit Gent); Mohan, Manu K. (Universiteit Gent); Tao, Yaxin (Universiteit Gent); Zhang, Yi (Universiteit Gent; Tongji University); Van Tittelboom, Kim (Universiteit Gent); Ye, G. (TU Delft Materials and Environment; Universiteit Gent); De Schutter, Geert (Universiteit Gent)","","2024","To properly control the reaction kinetics and fresh properties evolution in conventional alkali-activated materials (AAMs), a conceptual design of two-stream AAMs has been proposed in this study. This is achieved by dividing the solid and liquid components in AAMs, including blast furnace slag (BFS) and electric arc furnace slag (EFS) precursors, as well as aqueous sodium hydroxide and silicate activators into two separate streams A and B, where a very limited reactivity is expected in individual streams to ensure sufficient workability retention. Moreover, a final-stage intermixing is required to combine individual stream mixtures and trigger the major activation reaction. Fresh and hardened properties of combined mixtures were checked at different stages. The microstructure and reaction products were investigated to understand the strength development. Low dynamic rheological parameters and good workability retention have been detected in all individual stream mixtures, accompanied by limited exothermic heat flows after the initial dissolution confirmed by calorimetry tests. Further, Portland cement (PC) is partially blended into stream A to alter the early stiffening process in combined mixtures and meet various setting demands after intermixing. However, this might lead to a reduction in mechanical properties, associated with the formation of porous microstructures and an increase in the Ca/Si ratio in reaction products. Eventually, the conceptual design is validated in different scenarios including self-compacting and 3D-printing concrete applications.","3D-printing; Microstructure; Rheology; Self-compacting; Two-stream AAMs","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.","","2024-08-23","","","Materials and Environment","","",""
"uuid:f2f260e5-e00f-4e27-a53c-f9a4125368d2","http://resolver.tudelft.nl/uuid:f2f260e5-e00f-4e27-a53c-f9a4125368d2","Social and economic analysis of integrated building transportation energy system","Liu, Zhengxuan (TU Delft Design & Construction Management); Sun, Ying (Qingdao University of Technology); Huang, Ruopeng (Chongqing University)","Zhou, Yuekuan (editor); Yang, Jinglei (editor); Zhang, Guoqiang (editor); Lund, Peter D. (editor)","2024","The increasing greenhouse gas (CO2) emissions constitute one of the most significant global environmental issues. CO2 emissions from buildings and transportation are responsible for the largest proportion of total global carbon emissions from various sectors. Therefore it is necessary to utilize clean energy sources (e.g., renewable energy, energy storage systems, and electric vehicles) to decarbonize the building and transportation sectors. The integrated building transportation energy system (IBTES) is a system that combines the energy demands of buildings and transportation in an integrated manner. However, this integrated system has many issues in its practical applications, especially considering the social and economic aspects. A social and economic analysis of IBTES will consider the impacts on various stakeholders, including building owners and users, transportation users, energy suppliers, etc. This study will systematically summarize the current application and development status of IBTES from both social and economic perspectives. In terms of the social perspective, IBTES can improve energy efficiency and reduce CO2 emissions, which will have a positive impact on the environment and public health. From an economic perspective, IBTES has the potential to decrease the energy costs of buildings and transportation users. In addition, it has the potential to create new jobs in the energy and transportation sectors, and potentially attract new businesses and investments to a region. This study also summarizes several issues and challenges of IBTES, including the cost of implementing and maintaining the system, social acceptance, and inadequate related regulations. Based on this, the study proposes recommendations to effectively promote the implementation of IBTES. This study can provide some theoretical guidelines and suggestions for policymakers.","building transportation energy system; carbon neutrality; economic analysis; electric vehicles; energy storage system; renewable energy; social impact","en","book chapter","Elsevier","","","","","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.","","2024-05-21","","","Design & Construction Management","","",""
"uuid:77766c62-fd3a-4cdb-845e-269194bf19ec","http://resolver.tudelft.nl/uuid:77766c62-fd3a-4cdb-845e-269194bf19ec","Characterization, pre-treatment, and potential applications of fine MSWI bottom ash as a supplementary cementitious material","Sun, Y. (TU Delft Civil Engineering & Geosciences; Universiteit Gent); Chen, B. (TU Delft Materials and Environment); Zhang, Shizhe (TU Delft Materials and Environment); Blom, C.B.M. (TU Delft Concrete Structures; Gemeente Rotterdam); Lukovic, M. (TU Delft Concrete Structures); Ye, G. (TU Delft Materials and Environment; Universiteit Gent)","","2024","With the development of waste recovery techniques, previous research has revealed that coarse fractions of municipal solid waste incineration (MSWI) bottom ash (BA) after proper treatment could be applied in the construction sector, while the fines are seldom recovered in practice and normally landfilled. This study explores the potential application of fine MSWI BA (0–2 mm) as a supplementary cementitious material (SCM) in Portland cement (PC) mixtures. Mechanical and chemical pre-treatment approaches have been designed with various conditions to optimize the treating process. The chemical and mineralogical compositions, as well as the metallic Al content in BA were characterized before and after the pre-treatment. It was found that both methods are effective in removing the metallic Al content in BA, Moreover, BA derived from mechanical treatment exhibited more contribution to the hydration reaction in PC mixtures, as revealed by the amount of reaction products and mineral phases formed in hardened trial mixtures. BA obtained was further partially blended in PC mortars to evaluate the performance as compared to SCMs and inert fillers. It was found that treated BA resulted in a slight retarding effect on the reaction kinetics. Treated BA behaved better than the coal fly ash to contribute to the strength development, while the inclusion of BA did not lead to significant influences on the workability.","characterization; metallic Al; MSWI BA; pre-treatment; supplementary cementitious material","en","journal article","","","","","","","","","Civil Engineering & Geosciences","","Materials and Environment","","",""
"uuid:83e0a177-5c50-4e1e-9c49-afbf1f0d6073","http://resolver.tudelft.nl/uuid:83e0a177-5c50-4e1e-9c49-afbf1f0d6073","Multi-Level and Learning-Based Model Predictive Control for Traffic Management","Sun, D. (TU Delft Team Bart De Schutter)","De Schutter, B.H.K. (promotor); Jamshidnejad, A. (copromotor); Delft University of Technology (degree granting institution)","2023","This thesis focuses on management and control of traffic networks, including urban networks and freeway networks, in which we aim to reduce traffic congestion by minimizing the total time spent of all the vehicles in the network, and also consider green mobility by minimizing the total emissions produced by the vehicles. In this thesis, we have addressed the challenges of model predictive control (MPC) for traffic management in terms of computational complexity and model mismatches by developing several novel MPC-based control frameworks for urban and freeway traffic networks. More specifically, several multi-level and learning-based MPC control frameworks are proposed. First, a novel bi-level temporally-distributed MPC framework is proposed to deal with the green urban mobility issue that usually involves long-term (e.g., one year) emission constraints, and is thus computationally intractable due to the large window of the problem. Second, we employ a grammatical evolution method to generate parameterized control laws for parameterized MPC (PMPC) with application to urban traffic signal control. Third, we develop a novel combined MPC- deep reinforcement learning (DRL) multi-level control framework, in which the MPC module provides a basic control performance at a lower frequency based on a prediction model, and the DRL module works at a higher frequency to compensate for the model mismatches and external disturbances through learning. Forth, we propose a synthesis framework of reinforcement learning (RL)-based adaptive PMPC. In this framework, all components of the PMPC scheme, such as the cost function, the prediction model, the control law, the constraint set, and the terminal set, can be parameterized and adjusted by a high-level RL agent.","Model Predictive Control (MPC); Reinforcement Leaning (RL); Traffic Management; Multi-Level MPC; Learning-Based MPC","en","doctoral thesis","","978-90-5584-335-0","","","","","","","","","Team Bart De Schutter","","",""
"uuid:1280a3c4-b32b-4019-9903-c82996848040","http://resolver.tudelft.nl/uuid:1280a3c4-b32b-4019-9903-c82996848040","DeepPick: A Deep Learning Approach to Unveil Outstanding Users Ranking with Public Attainable Features","Li, Wanda (Fudan University); Xu, Zhiwei (Fudan University); Sun, Yi (Fudan University); Gong, Qingyuan (Fudan University); Chen, Y. (Fudan University); Ding, Aaron Yi (TU Delft Information and Communication Technology); Wang, Xin (Fudan University); Hui, Pan (The Hong Kong University of Science and Technology; University of Helsinki)","","2023","Outstanding users (OUs) denote the influential, 'core' or 'bridge' users in online social networks. How to accurately detect and rank them is an important problem for third-party online service providers and researchers. Conventional efforts, ranging from early graph-based algorithms to recent machine learning-based approaches, typically rely on an entire social network's information. However, for privacy-conscious users or newly-registered users, such information is not easily accessible. To address this issue, we present DeepPick, a novel framework that considers both the generalization and specialization in the detection task of OUs. For generalization, we introduce deep neural networks to capture dynamic features of the users. For specialization, we leverage the traditional descriptive features to make use of public information about users. Extensive experiments based on real-world datasets demonstrate that our approach achieves a high efficacy of detection performance against the state-of-the-art.","Bridges; Computer science; Deep Neural Networks; Feature extraction; Integrated circuit modeling; Neural networks; Online Social Networks; Outstanding User Detection; Social networking (online); Task analysis","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.","","2023-07-01","","","Information and Communication Technology","","",""
"uuid:6dc71712-0a4c-4ba5-b253-55131d774027","http://resolver.tudelft.nl/uuid:6dc71712-0a4c-4ba5-b253-55131d774027","Silicon carbide-on-insulator thermal-piezoresistive resonator for harsh environment application","Sun, B. (TU Delft Electronic Components, Technology and Materials; China University of Petroleum (East China)); Mo, J. (TU Delft Electronic Components, Technology and Materials); Zhang, Hemin (Katholieke Universiteit Leuven); van Zeijl, H.W. (TU Delft Electronic Components, Technology and Materials); van Driel, W.D. (TU Delft Electronic Components, Technology and Materials); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2023","The thermal-piezoresistive effect in silicon (Si) has attracted great attention toward high-performance resonant devices but still faces major challenges for harsh environment applications. Instead of using Si, this paper, for the first time, reports a thermal-piezoresistive resonator based on a silicon carbide-on-insulator (SiCOI) platform. The resonance frequency simulation, CMOS-compatible fabrication, and thermoresistive properties characterization of the proposed SiCOI resonator are presented. The experimental results show linear current-voltage characteristics and a constant temperature coefficient of resistance (TCR) up to 200 °C.","Silicon carbide-on-insulator; thermal-piezoresistive; resonator; harsh environment","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.","","2023-09-01","","","Electronic Components, Technology and Materials","","",""
"uuid:2de89733-b611-4e11-9403-9b97d9a7fa63","http://resolver.tudelft.nl/uuid:2de89733-b611-4e11-9403-9b97d9a7fa63","A Novel High-temperature Pressure Sensor Based on Graphene Coated by Si3N4","Zeng, Simei (Beijing Jiaotong University); Tang, Chenggang (Beijing Jiaotong University); Hong, H. (TU Delft Electronic Components, Technology and Materials); Yuan, Fang (Beijing Jiaotong University); Li, Yuning (Beijing Jiaotong University); Wang, Yuqiang (Beijing Jiaotong University); Kong, Lingbing (Beijing Jiaotong University); Sun, Jingye (Beijing Jiaotong University); Zhu, Mingqiang (Beijing Jiaotong University); Deng, Tao (Beijing Jiaotong University)","","2023","The high-temperature pressure sensors have wide applications in aerospace, petroleum, geothermal exploration, automotive electronics, and other fields. However, the traditional silicon-based pressure sensors are restricted to pressure measurement under 120~{\circ }\text{C} and cannot be satisfied to measure the pressure of various gases or liquids in high temperature and other harsh environments. This article proposes a novel high-temperature pressure sensor based on graphene, in which a rectangular cavity is applied to improve the piezoresistive characteristics of the sensor. The unique of this sensor is that the graphene is coated by the silicon nitride (Si3N4) membrane, which could avoid the oxidation of graphene in high temperature and increase the temperature tolerance range. The sensor was placed at various temperatures ( 50~{\circ }\text{C} - 420~{\circ }\text{C} ) to explore the temperature characteristics, achieving a maximal temperature coefficient of resistance (TCR) of 0.322% {\circ }\text{C}{-{1}}. Moreover, the sensor with a 64 \times 9\,\,\mu \text{m}{{2}} cavity has a high pressure sensitivity of 5.32\times 10{-{4}} kPa {-{1}} , enabling a wide range from 100 kPa to 10 Pa. Experimental results indicate that the proposed sensor possesses superior pressure sensitivity, a wide pressure detection range, and a high-temperature tolerance of 420~{\circ }\text{C} , which provides new insight into fabricating high-temperature pressure sensors based on graphene and creates more applications in different fields.","Graphene; high-temperature; Si3N4; piezoresistive characteristic","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.","","2023-08-01","","","Electronic Components, Technology and Materials","","",""
"uuid:289721dc-db65-400d-8f29-45b15903a1dd","http://resolver.tudelft.nl/uuid:289721dc-db65-400d-8f29-45b15903a1dd","Effects of nanobubbles on methane hydrate dissociation: A molecular simulation study","Fang, B. (TU Delft Engineering Thermodynamics; China University of Geosciences); Moultos, O. (TU Delft Engineering Thermodynamics); Lü, Tao (China University of Geosciences; Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems,); Sun, Jiaxin (China University of Geosciences); Liu, Z. (China University of Geosciences); Ning, Fulong (Qingdao National Laboratory for Marine Science and Technology; China University of Geosciences); Vlugt, T.J.H. (TU Delft Engineering Thermodynamics)","","2023","Hydrate dissociation is often accompanied by the formation of nanobubbles. Knowledge of the effects of nanobubbles on hydrate dissociation is essential for understanding the dynamic behavior of the hydrate phase change and improving the gas production efficiency. Here, molecular dynamics simulations were performed to study the methane hydrate dissociation kinetics with and without a pre-existing methane nanobubble. The results show that the hydrate cluster in the liquid phase dissociates layer-by-layer. This process is shown to be independent of the temperature and nanobubble presence at the simulation conditions. Hydrate dissociation does not always lead to nanobubble formation because the supersaturated methane solution can be stable for a long time. A steep methane concentration gradient was observed between the hydrate cluster surface and the methane nanobubble, which can enhance the directional migration of methane and effectively minimize the methane concentration in the liquid phase, thereby increasing the driving force for the hydrate dissociation. Our findings indicate that the presence of a nanobubble near the hydrate surface does not decrease the activation energy of hydrate dissociation, but it can increase the intrinsic decomposition rate. The average hydrate dissociation rate is linearly correlated with the mass flow rate towards the nanobubble. The mass flow rate is determined by the nanobubble size and hydrate-nanobubble distance. Our findings contribute to the fundamental understanding of the dissociation mechanism of gas hydrates in the liquid phase, which is crucial for the design and optimization of efficient gas hydrate production techniques.","","en","journal article","","","","","","","","","","","Engineering Thermodynamics","","",""
"uuid:95ea6576-69d7-4ecc-a0d7-35e616562253","http://resolver.tudelft.nl/uuid:95ea6576-69d7-4ecc-a0d7-35e616562253","Unprotected Left-Turn Behavior Model Capturing Path Variations at Intersections","Zhao, Jing (University of Shanghai for Science and Technology); Knoop, V.L. (TU Delft Transport and Planning); Sun, Jian (Tongji University); Ma, Zian (Tongji University); Wang, M. (TU Delft Transport and Planning; Technische Universität Dresden)","","2023","Path dispersion (the spatial distribution of vehicular paths) is an important feature of traffic flow inside intersections and differs from traffic flow running along traffic lanes at road segment, especially under conflicting movements. The path dispersion reflects the operational features of traffic flow and is related to driving behaviour, arrival flow patterns, layout design, and the traffic control and management scheme. This study aims to improve the understanding of the overall path dispersion of unprotected left-turns and the opposing through movement. A behavioural simulation model was established to represent the overall path dispersion. Human behaviours regarding vehicle trajectory planning with and without conflicting vehicles were modelled based on optimal control and integrated into the proposed discrete event simulation framework. The descriptive power and accuracy of the proposed simulation model were validated using empirical data. The effects of the spatial size of the intersection, crossing angle, and traffic volume on the path dispersion of the left-turn and through movement were explored based on numerical experiments. The results show that the proposed simulation model can represent the path dispersion of left-turn and opposing through movement well for both the calibrated intersections and newly added intersections without model parameter recalibration with an average error of 8.92%.","Path dispersion; driving behaviors; conflicting movements; intersections","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.","","2023-11-03","","Transport and Planning","Transport and Planning","","",""
"uuid:284b17af-71ee-4e79-b75e-0cc3b9ce6079","http://resolver.tudelft.nl/uuid:284b17af-71ee-4e79-b75e-0cc3b9ce6079","Optimizing ML Inference Queries Under Constraints","Li, Z. (TU Delft Web Information Systems); Sun, W. (TU Delft Web Information Systems); Hai, R. (TU Delft Web Information Systems); Bozzon, A. (TU Delft Human-Centred Artificial Intelligence); Katsifodimos, A (TU Delft Web Information Systems)","","2023","The proliferation of pre-trained ML models in public Web-based model zoos facilitates the engineering of ML pipelines to address complex inference queries over datasets and streams of unstructured content. Constructing optimal plan for a query is hard, especially when constraints (e.g. accuracy or execution time) must be taken into consideration, and the complexity of the inference query increases. To address this issue, we propose a method for optimizing ML inference queries that selects the most suitable ML models to use, as well as the order in which those models are executed. We formally define the constraint-based ML inference query optimization problem, formulate it as a Mixed Integer Programming (MIP) problem, and develop an optimizer that maximizes accuracy given constraints. This optimizer is capable of navigating a large search space to identify optimal query plans on various model zoos.","","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.","","2023-12-25","","","Web Information Systems","","",""
"uuid:3b942384-88fd-4bfa-8bfa-a05e8eb2068c","http://resolver.tudelft.nl/uuid:3b942384-88fd-4bfa-8bfa-a05e8eb2068c","Distinctive sedimentary processes on two contrasting tidal flats of the Yellow River Delta","Xie, Weiming (East China Normal University); Sun, J. (TU Delft Coastal Engineering); Guo, Leicheng (East China Normal University); Xu, Fan (East China Normal University); Wang, Xianye (East China Normal University); Ji, Hongyu (East China Normal University); Fan, Yaoshen (Yellow River Conservancy Commission); Wang, Zhengbing (TU Delft Coastal Engineering; Deltares); He, Qing (East China Normal Univeristy)","","2023","Coastal tidal flats provide valuable ecosystems, but are highly sensitive to tidal dynamics, sea-level rise, and human activities. Tidal inundation depth and frequency are known to affect tidal flat morphodynamics. However, the causes, processes and extent remain uncertain, particularly given the associated changes in sediment availability. In this study, we monitored the hydrodynamics, sediment transport, and morphological changes on two tidal flats in the northern and southern parts of the Yellow River Delta, with contrasting tidal regimes. The data showed that longer inundation periods under diurnal tides gained additional sediment and deposition than under semi-diurnal tides, because of the associated increase in water depth and sediment availability. The wave impact increased at the site with a semi-diurnal tidal regime owing to the lower water depth, where a larger bed shear stress led to tidal flat erosion. These results indicated that the combination of tidal regime and the occurrence of powerful waves played a joint role in controlling bed erosion, sediment availability, and short-term tidal flat evolution. This has implications for coping with delta erosion by enhancing local sediment availability in diurnal tidal regions and restoring vegetation to attenuate waves in semi-diurnal regions of the Yellow River Delta.","tidal flat; hydrodynamics; sediment dynamics; inundation period; Yellow River Delta","en","journal article","","","","","","","","","","","Coastal Engineering","","",""
"uuid:896db6a9-7132-4204-8e1b-35fac45c6090","http://resolver.tudelft.nl/uuid:896db6a9-7132-4204-8e1b-35fac45c6090","A novel bi-level temporally-distributed MPC approach: An application to green urban mobility","Jamshidnejad, A. (TU Delft Control & Simulation); Sun, D. (TU Delft Transport and Planning; TU Delft Team Bart De Schutter); Ferrara, Antonella (Pavia University); De Schutter, B.H.K. (TU Delft Delft Center for Systems and Control)","","2023","Model predictive control (MPC) has been widely used for traffic management, such as for minimizing the total time spent or the total emissions of vehicles. When long-term green urban mobility is considered including e.g. a constraint on the total yearly emissions, the optimization horizon of the MPC problem is significantly larger than the control sampling time, and thus the number of the variables that should be optimized per control time step becomes very large. For systems with dynamics that involve nonlinear, non-convex, and non-smooth functions, including urban traffic networks, this results in optimization problems that are computationally intractable in real time. In this paper, we propose a novel bi-level temporal distribution of such complex MPC optimization problems, and we develop two mathematically linked short-term and long-term MPC formulations with small and large control sampling times that will be solved together instead of the original complex optimization problem. The resulting bi-level control architecture is used to solve the two MPC formulations online for real-time control of urban traffic networks with the objective of long-term green mobility. In order to assess the performance of the bi-level control architecture, we perform a case study where a rough version of the model of the urban traffic flow, S-model, is used by the long-term MPC level to estimate the states of the urban traffic networks, and a detailed version of the model is used by the short-term MPC level. The results of the simulations prove the effectiveness (with respect to the objective of control, as well as computational efficiency) of the proposed bi-level MPC approach, compared to state-of-the-art control approaches.","Temporally distributed MPC; Multiple-frequency control; Green urban mobility","en","journal article","","","","","","","","","","Delft Center for Systems and Control","Control & Simulation","","",""
"uuid:cf855c03-e5f0-4812-a330-c930922b08f9","http://resolver.tudelft.nl/uuid:cf855c03-e5f0-4812-a330-c930922b08f9","Environmental inefficiencies for arrival flights at European airports","Olive, Xavier (ENSIACET); Sun, Junzi (TU Delft Control & Simulation); Basora, Luis (Université de Toulouse; ENSIACET); Spinielli, Enrico (EUROCONTROL)","","2023","In this paper, we analyze two months of trajectory data for aircraft landing in five major European airports. Based on open ADS-B data from the OpenSky Network and open performance models, we enrich all trajectories with automatically detected procedure information, fuel consumption, and emissions for supported aircraft types. To assess the inefficiencies associated with holding patterns, point merges, and continuous descent operations across different airports, we propose methodologies to quantify and compare these environmental inefficiencies. Holding patterns are found to have a higher negative impact on the environment than point merge and continuous descent operations. Furthermore, the paper provides recommendations for procedure evaluations of future airports, which could help policymakers and relevant stakeholders to evaluate the environmental performances of arrival procedures based on open data and open models","","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:cd2fc346-c911-41cc-875f-419ce63f4519","http://resolver.tudelft.nl/uuid:cd2fc346-c911-41cc-875f-419ce63f4519","Scenario-based performance assessment of green-grey-blue infrastructure for flood-resilient spatial solution: A case study of Pazhou, Guangzhou, greater Bay area","Lu, P. (TU Delft Landscape Architecture; South China University of Technology); Sun, Yimin (South China University of Technology); Nijhuis, S. (TU Delft Landscape Architecture)","","2023","Flood resilience has aroused significant interest in coastal areas dealing with a growing frequency of severe rainstorms caused by climate change and urbanisation. At the core of flood resilience is the development of a resilient green-grey-blue infrastructure system that can resist, absorb, and recover from floods in a timely manner. Current flood resilience research, however, is limited to evaluating single infrastructure systems, failing to examine the dynamic process or find ideal spatial infrastructure designs for decision-makers. This research proposes a scenario-based assessment framework for integrated green-grey-blue infrastructure systems to improve flood resilience during urban design decision-making. Rainfall-runoff, drainage networks, and river system models are interlinked to provide quantitative simulation evaluations of water quantity and urban impact in various spatial organisations of infrastructure design. A dynamic, multi-criteria decision-making process is used to reveal the importance of five temporal indicators and rank design alternatives. In Guangzhou, China, the efficiency of this architecture is demonstrated on Pazhou Island, a typical river network area. Given the limited water and green space available, the results demonstrate that submerged areas exert a greater influence during peak rainfall, and blue infrastructure storage becomes an essential factor following rainfall. Furthermore, from a spatial perspective, the looped network of green-blue infrastructure enhances flood resilience, and downstream waterway connections and green space-aligned waterways boost the water storage capacity of green-grey-blue infrastructure. This paradigm can improve flood resilience in the Greater Bay Area in the future, especially in response to heavy rainstorms and river floods.","Flood resilience; Green-grey-blue infrastructure systems; Performance assessment; Inundation model; TOPSIS","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.","","2023-12-15","","","Landscape Architecture","","",""
"uuid:394b169e-51c7-401a-8646-796ffaf45f14","http://resolver.tudelft.nl/uuid:394b169e-51c7-401a-8646-796ffaf45f14","OpenSky Report 2023: Low Altitude Traffic Awareness for Light Aircraft with FLARM","Olive, Xavier (OpenSky Network, Burgdorf; Université de Toulouse); Strohmeier, Martin (OpenSky Network, Burgdorf; Armasuisse); Sun, Junzi (TU Delft Control & Simulation; OpenSky Network, Burgdorf); Tresoldi, Giorgio (OpenSky Network, Burgdorf; Armasuisse)","","2023","Established in 2013, The OpenSky Network, a crowdsourced network of ADS-B receivers, has consistently collected surveillance data from equipped aircraft and made it available for science. Coverage has steadily improved, boasting more than 6000 registered sensors worldwide today. This platform has aided numerous researchers in publishing studies across fields such as air traffic management, security, environment, and radio frequency interference. Following the 2020 mandate, most aircraft flying at high altitudes in Europe or Northern America are within range of one of the network’s ADS-B receivers. To complement existing research using OpenSky data, this paper focuses on lower altitude coverage, including light aircraft, general aviation, gliders, and ultralights, which are not required to carry ADS-B transponders. Instead, these often use, esp. in Europe, another traffic awareness and collision avoidance technology known as FLARM. The OpenSky Network has been gathering FLARM messages since 2018, and now enough data is available for a detailed analysis. The aim of this report is to present OpenSky’s FLARM data, explain the workings of the technology, and highlight potential uses of this data for future research.","","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.","","2024-05-10","","","Control & Simulation","","",""
"uuid:2520a413-58fb-4028-8ce0-802a30741392","http://resolver.tudelft.nl/uuid:2520a413-58fb-4028-8ce0-802a30741392","The collective realms in the Chinese city: Towards an alternative framework for public space","Sun, W. (TU Delft Urban Design)","","2023","A western discourse of public space, originating in ancient Greece and Rome, has been widely used in architectural and urban research in China and is constantly contested in this geographical and cultural context. The contestation often stems from the cultural differences in understanding and operating the collective realms in Chinese and western cities, which is manifested through the distinctive features of their public spaces. This essay frames an alternative perspective on public space in the Chinese context by exploring the cultural, social, and spatial constructions of collective realms in the Chinese city. Starting from the conceptual origin of the ‘public’ in Chinese philosophy, this paper elaborates on three culturally grounded ideas related to collective patterns of space creation and practice – the relational circle, the realm of strangers, and the marketplace – and examines how these ideas are articulated by architectural and urban archetypes and in urban developments in Chinese cities.","Chinese city; collective realms; realm of strangers; relational circle; marketplace; public space","en","journal article","","","","","","","","","","","Urban Design","","",""
"uuid:5edb97f8-bdb2-4f6e-be53-d8e261d0c4e1","http://resolver.tudelft.nl/uuid:5edb97f8-bdb2-4f6e-be53-d8e261d0c4e1","A Landscape-Based Regional Design Approach for Sustainable Urban Development in the Pearl River Delta, China","Nijhuis, S. (TU Delft Landscape Architecture); Sun, Yimin (South China University of Technology); Cannatella, D. (TU Delft Landscape Architecture); Xie, G. (TU Delft Landscape Architecture)","Nijhuis, Steffen (editor); Sun, Yimin (editor); Lange, Eckart (editor)","2023","Adaptive urban transformations employ landscape-based regional design as an integrative and multiscale design and planning approach for sustainable urban development. In this approach, natural and urban dynamics as derived from systems analysis set the pace and nature of adaptation. This chapter presents an initial strategy for adaptive urban transformation in the Pearl River Delta to illustrate the potential of landscape-based regional design as form of territorial governance that takes the natural and urban landscape as the basis to steer urban–rural transformative processes through a combination of sector activities towards more coordinated sustainable outcomes. The strategic spatial plan and subsequent implementation by means of pilot projects will focus on the potential of interlinked economic and ecological development at multiple scales. Together with the assessment of urban landscape growth over time and the evaluation of current spatial development projects in the region, several significant factors of future development have been identified, leading to an initial strategic vision and transformation perspectives for the PRD. This vision is based on the idea that the PRD will develop into China's Silicon Valley, with strongly developed and well-connected urban qualities, robust green–blue frameworks, cultural-historical assets connected to the region and water-sensitive socio-ecological inclusive urbanism.","adaptive urban transformation; Landscape-based regional design; vision pearl river delta; transformation perspectives; adaptive design principles","en","book chapter","Springer Nature","","","","","","","","","","Landscape Architecture","","",""
"uuid:4f8c0b88-041d-4a95-80cd-f5b4dec34a5c","http://resolver.tudelft.nl/uuid:4f8c0b88-041d-4a95-80cd-f5b4dec34a5c","Introduction: Adaptive Urban Transformation in the Pearl River Delta, China.","Nijhuis, S. (TU Delft Landscape Architecture); Sun, Yimin (South China University of Technology); Lange, Eckart (University of Sheffield)","Nijhuis, Steffen (editor); Sun, Yimin (editor); Lange, Eckart (editor)","2023","Deltaic areas are amidst the most favourable territories around the globe. Their strategic location and superior quality of their soils are core factors supporting both human development and the rise of these regions as global economic hubs. At the same time, deltas are extremely vulnerable to multiple threats from both climate change and the rush to urbanisation. These include an increased flood risk combined with the loss of ecological and social–cultural values. To ensure a more sustainable future for urbanising deltas, spatial strategies are needed to strengthen resilience, i.e. help the systems to cope with their vulnerabilities as well as enhance their capacity to overcome natural and anthropogenic threats. In this chapter, we outline the basic concepts and backgrounds of a joint research project with academic and societal partners called adaptive urban transformation. The objective of this research is to develop and test an integrative and multiscale design and planning approach for the adaptive urban transformation of urbanising deltas, in which the Pearl River Delta serves as a case study. In this approach, landscape-based regional design plays a key role in adaptive urban transformation, as well as innovative participation and visualisation techniques. Applications in urban design, planning, and governance in the PRD are also introduced. This chapter is foundational for the rest of the research presented in the chapters in this volume.","Resilient urban planning and management; Landscape-based regional design; Adaptive urban planning; visualisation; stakeholder participation; chief urban designer system; territorial governance","en","book chapter","Springer Nature","","","","","","","","","","Landscape Architecture","","",""
"uuid:aa1ffcd7-613a-4742-8c1e-3366d4efce1c","http://resolver.tudelft.nl/uuid:aa1ffcd7-613a-4742-8c1e-3366d4efce1c","Special Issue: Advanced Modeling and Design for Composite Materials and Structures","Zhong, Yucheng (Wuhan University of Technology); Wu, Tao (Technische Universität Dresden); Sun, Guangyong (Hunan University); Cherniaev, Aleksandr (University of Windsor); Alderliesten, R.C. (TU Delft Structural Integrity & Composites)","","2023","","","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.","","2024-01-17","","","Structural Integrity & Composites","","",""
"uuid:640cbd21-caab-400f-a80f-09f9aef09181","http://resolver.tudelft.nl/uuid:640cbd21-caab-400f-a80f-09f9aef09181","Contrail Altitude Estimation Based on Shadows Detected in Landsat Imagery","Roosenbrand, E.J. (TU Delft Control & Simulation); Sun, Junzi (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2023","Contrails contribute to global warming by trapping outgoing terrestrial radiation, exerting an immediate warming influence on the climate. The climatic impact of contrails is potentially comparable to that of aviation’s carbon emissions. This underlines the importance of minimizing contrail formation to mitigate the climate effects of aviation, both now and in the future. The evaluation of contrails demands more precise data on the location and altitude where they form. Remote sensing imagery enables the identification of their location. Nevertheless, determining the altitude of the contrail remains problematic, complicating the identification of the source flight. This study introduces a novel method that enables researchers to determine the altitude of a contrail solely using Landsat data by analysing shadows cast by contrails. Through validation against ADS-B data from OpenSky, we demonstrate that such a technique can achieve the accuracy of a few hundreds of meters, which is suitable for incorporation into a climate-optimized routing system. Finally, a ResUNet segmentation model is also presented, which can identify contrails and their shadows in Landsat imagery. These results constitute a step forward for more accurate contrail dataset and models.","Sustainability; Contrails; Remote Sensing; Atmospheric Science; OpenSky; Aircraft Surveillance Data","en","conference paper","","","","","","","","","","","Control & Simulation","","",""
"uuid:3b088eff-8705-423c-b62f-56d44c60df3e","http://resolver.tudelft.nl/uuid:3b088eff-8705-423c-b62f-56d44c60df3e","Evaluating Transatlantic Flight Emissions and Inefficiencies Using Space-Based ADS-B Data","Sun, Junzi (TU Delft Control & Simulation); Tassanbi, A. (TU Delft Control & Simulation); Obojski, Piotrek (Spire Global); Plantholt, Philip (Spire Global)","","2023","The increasing demand for global air travel has intensified the urgency to mitigate aviation’s carbon emissions. Continuous monitoring of aircraft fuel efficiency and emissions has become an important task in aviation. One of the main challenges has been the lack of surveillance data for flights across oceans, specifically in the North Atlantic region, where numerous flights occur. Recently, space-based ADS-B data has been made available by new space companies like Spire Global, enabling flight surveillance for aircraft in remote regions, including transatlantic flights. In this study, we utilize several months of space-based ADS-B data from Spire, combined with groundbased ADS-B data from the OpenSky Network, to demonstrate increased accuracy in flight trajectory and emission estimations. We introduce the use of wind data to improve emission quantification. Utilizing these accurate trajectories, we quantify excess emissions by comparing actual flight paths with their optimal alternatives. Our approach provides a robust methodology that benefits future policy for carbon emissions assessments.","ADS-B; Flight emissions; OpenSky; Spire Global","en","conference paper","","","","","","","","","","","Control & Simulation","","",""
"uuid:5c26fd2f-6333-4297-aaa0-d747f8e3b818","http://resolver.tudelft.nl/uuid:5c26fd2f-6333-4297-aaa0-d747f8e3b818","Water Narratives: Exploring the Convergence of the Canal du Midi and Its Coastal Landscape","Bobbink, I. (TU Delft Landscape Architecture); Chouairi, A. (University IUAV of Venice); Sun, P. (Student TU Delft)","","2023","Considering ‘infrastructures as landscapes’ and ‘landscapes as infrastructures’, this article uses an open framework to reconsider the distinctive water infrastructure of France’s UNESCO-listed heritage Canal du Midi. More specifically, it profiles the Canal’s Mediterranean outlet. Viewed through a landscape architectonic lens, we investigate the canal, drawing on the theory of landscape narrative and using the illustrative method. The article identifies three crucial narratives – infrastructural, natural & environmental and social & cultural – that help to examine the spatial values of the Canal and its relationship with its southern coastal landscape. The study shows how the Canal du Midi has been transformed and has influenced its surroundings, becoming an integral part of the coastal landscape. We identify and analyse how the Canal functions as an infrastructure composition and an environmentally and culturally significant feature. The landscape narrative framework offers the possibility of sharpening the interpretation of water infrastructures beyond conventional problem-solving approaches by providing a holistic view of the Canal and its water landscapes. This, in turn, offers inspiration for the region's future development, which presently prioritises the preservation of the Canal du Midi and the regeneration of the surrounding area as distinct projects.","landscape infrastructure; illustrative method; landscape narrative; Canal du Midi; coastal landscape","en","journal article","","","","","","","","","","","Landscape Architecture","","",""
"uuid:fcb2e304-53af-4c26-9bc5-c97b71856126","http://resolver.tudelft.nl/uuid:fcb2e304-53af-4c26-9bc5-c97b71856126","Accelerating Machine Learning Queries with Linear Algebra Query Processing","Sun, W. (TU Delft Web Information Systems); Katsifodimos, A (TU Delft Web Information Systems); Hai, R. (TU Delft Web Information Systems)","Schuler, Robert (editor); Kesselman, Carl (editor); Chard, Kyle (editor); Bugacov, Alejandro (editor)","2023","The rapid growth of large-scale machine learning (ML) models has led numerous commercial companies to utilize ML models for generating predictive results to help business decision-making. As two primary components in traditional predictive pipelines, data processing, and model predictions often operate in separate execution environments, leading to redundant engineering and computations. Additionally, the diverging mathematical foundations of data processing and machine learning hinder cross-optimizations by combining these two components, thereby overlooking potential opportunities to expedite predictive pipelines. In this paper, we propose an operator fusing method based on GPU-accelerated linear algebraic evaluation of relational queries. Our method leverages linear algebra computation properties to merge operators in machine learning predictions and data processing, significantly accelerating predictive pipelines by up to 317x. We perform a complexity analysis to deliver quantitative insights into the advantages of operator fusion, considering various data and model dimensions. Furthermore, we extensively evaluate matrix multiplication query processing utilizing the widely-used Star Schema Benchmark. Through comprehensive evaluations, we demonstrate the effectiveness and potential of our approach in improving the efficiency of data processing and machine learning workloads on modern hardware.","database; machine learning; operator fusion; query optimization","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Web Information Systems","","",""
"uuid:dfc86a37-1fd8-477d-a08d-ce504220f9d6","http://resolver.tudelft.nl/uuid:dfc86a37-1fd8-477d-a08d-ce504220f9d6","Estimation of Cardiac Fibre Direction Based on Activation Maps","de Vries, J.W. (TU Delft Signal Processing Systems); Sun, M. (TU Delft Signal Processing Systems); de Groot, N.M.S. (Erasmus MC); Hendriks, R.C. (TU Delft Signal Processing Systems)","","2023","Estimating tissue conductivity parameters from electrograms (EGMs) could be an important tool for diagnosing and treating heart rhythm disorders such as atrial fibrillation (AF). One of these parameters is the fibre direction, often assumed to be known in conductivity estimation methods. In this paper, a novel method to estimate the fibre direction from EGMs is presented. This method is based on local conduction slowness vectors of a propagating activation wave. These conduction slowness vectors follow an elliptical pattern that depends on the underlying conductivity parameters. The fibre direction and conductivity anisotropy ratio can therefore be estimated by fitting an ellipse to the conduction slowness vectors. Applying the presented method on simulated data shows that it can estimate the fibre direction more accurately than existing methods, and that its performance depends mostly on the range of wavefront directions present in the measurement area. The main advantage of the presented method is that it still functions relatively well in the presence of conduction blocks, as long as the surrounding tissue is approximately homogeneous.","Anisotropy; atrial fibrillation; conduction velocity; fibre direction; local activation time","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.","","2023-11-05","","","Signal Processing Systems","","",""
"uuid:5d5621c8-d102-4f74-b41e-efe3507dd769","http://resolver.tudelft.nl/uuid:5d5621c8-d102-4f74-b41e-efe3507dd769","Adaptive Parameterized Control for Coordinated traffic Management Using Reinforcement Learning","Sun, D. (TU Delft Transport and Planning); Jamshidnejad, A. (TU Delft Control & Simulation); De Schutter, B.H.K. (TU Delft Delft Center for Systems and Control)","","2023","Traffic control is essential to reduce congestion in both urban and freeway traffic networks. These control measures include ramp metering and variable speed limits for freeways, and traffic signal control for urban traffic. However, current traffic control methods are either too simple to respond to complex traffic environment, or too sophisticated for real-life implementation. In this paper, we propose an adaptive parameterized control method for traffic management by using reinforcement learning algorithms. This method takes advantage of the simple structure of parameterized state-feedback controllers for traffic; meanwhile, a reinforcement learning agent is employed to adjust the parameters of the controllers on-line to react to the varying environment. Therefore, the proposed method requires limited real-time computational efforts, and is adaptive to external disturbances. Furthermore, the reinforcement learning agent can coordinate multiple local traffic controllers when adjusting their parameters. The method is validated by a numerical case study on a freeway network. Results show that the proposed method outperforms conventional controllers when the system is exposed to a changing environment.","Parameterized control; adaptive control; reinforcement learning; coordinated control; traffic network system","en","journal article","","","","","","","","","","Delft Center for Systems and Control","Transport and Planning","","",""
"uuid:4f909abd-c4ea-455c-b91a-590a10cdb1e4","http://resolver.tudelft.nl/uuid:4f909abd-c4ea-455c-b91a-590a10cdb1e4","How to keep it adequate: A protocol for ensuring validity in agent-based simulation","Troost, Christian (University of Hohenheim); Huber, Robert (ETH Zürich); Bell, Andrew R. (Boston University); van Delden, Hedwig (Research Institute for Knowledge Systems); Filatova, T. (TU Delft Multi Actor Systems; TU Delft Policy Analysis); Le, Quang Bao (International Center for Agricultural Research in the Dry Areas); Lippe, Melvin (Thünen Institute of Forestry); Niamir, Leila (International Institute for Applied Systems Analysis, Laxenburg); Polhill, J. Gareth (The James Hutton Institute); Sun, Zhanli (Leibniz Institute of Agricultural Development in Transition Economies); Berger, Thomas (University of Hohenheim)","","2023","There has so far been no shared understanding of validity in agent-based simulation. We here conceptualise validation as systematically substantiating the premises on which conclusions from simulation analysis for a particular modelling context are built. Given such a systematic perspective, validity of agent-based models cannot be ensured if validation is merely understood as an isolated step in the modelling process. Rather, valid conclusions from simulation analysis require context-adequate method choices at all steps of the simulation analysis including model construction, model and parameter inference, uncertainty analysis and simulation. We present a twelve-step protocol to highlight the (often hidden) premises for methodological choices and their link to the modelling context. It is designed to aid modelers in understanding their context and in choosing and documenting context-adequate and mutually consistent methods throughout the modelling process. Its purpose is to assist reviewers and the community as a whole in assessing and discussing context-adequacy.","Calibration; Generalisation; Model inference; Model validation; Regime shift","en","journal article","","","","","","","","","","Multi Actor Systems","Policy Analysis","","",""
"uuid:95d9e5ba-6bac-4dc7-a864-1e2225b4871e","http://resolver.tudelft.nl/uuid:95d9e5ba-6bac-4dc7-a864-1e2225b4871e","Risk consequence assessment of dam breach in cascade reservoirs considering risk transmission and superposition","Wang, Te (Zhengzhou University); Li, Zongkun (Zhengzhou University); Ge, W. (TU Delft Safety and Security Science; Zhengzhou University; Yellow River Engineering Consulting Co); zhang, Z.H. (Zhengzhou University); Zhang, Yadong (Zhengzhou University); Sun, Heqiang (Zhengzhou University); Jiao, Yutie (Zhengzhou University)","","2023","Compared with a single reservoir, the risk in cascade reservoirs has the transmission and superposition effect, which increases the complexity of its risk consequence assessment. In view of this problem, the direct consequence (DC) and potential consequence (PC) were defined as two parts of the dam breach risk consequence of cascade reservoirs. The upstream dam-break flood inundation line and the downstream reservoir land acquisition line were taken as the upper and lower boundaries of the assessment space, which made the risk consequence assessment more intuitive and further improved its scientificity and practicability. Subsequently, the conditional probability of downstream dam breach under the upstream dam-break flood was determined to quantify the risk transmission and superposition. On this basis, the relevant concepts and formulas for calculating the dam breach risk consequence in cascade reservoirs were proposed. Taking five cascade reservoirs as examples, the risk consequences of each cascade dam breach were evaluated. The results show that the proposed method is effective in assessing the risk consequence of dam breach in cascade reservoirs and is more in line with the connotation of dam risk management, which can provide reference for the design and risk control of cascade reservoirs.","Cascade reservoirs; Dam breach; Loss; Risk management; Risk transmission","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.","","2023-07-01","","","Safety and Security Science","","",""
"uuid:c20e13d9-14fb-48ea-94e1-df74d47a73a5","http://resolver.tudelft.nl/uuid:c20e13d9-14fb-48ea-94e1-df74d47a73a5","Grammatical-Evolution-based parameterized Model Predictive Control for urban traffic networks","Jeschke, J.M. (TU Delft Team Bart De Schutter; CGI Nederland B.V); Sun, D. (TU Delft Team Bart De Schutter); Jamshidnejad, A. (TU Delft Control & Operations; TU Delft Control & Simulation); De Schutter, B.H.K. (TU Delft Delft Center for Systems and Control)","","2023","While Model Predictive Control (MPC) is a promising approach for network-wide control of urban traffic, the computational complexity of the, often nonlinear, online optimization procedure is too high for real-time implementations. In order to make MPC computationally efficient, this paper introduces a parameterized MPC (PMPC) approach for urban traffic networks that uses Grammatical Evolution to construct continuous parameterized control laws using an effective simulation-based training framework. Furthermore, a projection-based method is proposed to remove the nonlinear constraints that are imposed on the parameters of the parameterized control laws and to guarantee the feasibility of the solution of the MPC optimization problem. The performance and computational efficiency of the constructed parameterized control laws are compared to those of a conventional MPC controller in an extensive simulation-based case study. The results show that the parameterized control laws, which are automatically constructed using Grammatical Evolution, decrease the computational complexity of the online optimization problem by more than 80% with a decrease in performance by less than 10%.","Grammatical Evolution; Model Predictive Control; Parameterized controller; Urban traffic control","en","journal article","","","","","","","","","","Control & Operations","Team Bart De Schutter","","",""
"uuid:d88294bb-5fe9-41ee-9a1b-ba9b8f5a6881","http://resolver.tudelft.nl/uuid:d88294bb-5fe9-41ee-9a1b-ba9b8f5a6881","Behavior of Engineered Cementitious Composites (ECCs) Subjected to Coupled Sustained Flexural Load and Salt Frost","Li, Yonghao (Shandong University); Zhang, Ning (Shandong Hi-Speed Engineering Test CO); Sun, Renjuan (Shandong University); Guan, Yanhua (Shandong University); Liu, Lemin (Shandong Expressway Infrastructure Construction Co); Tian, Changjin (Shandong University); Ling, Yifeng (Shandong University); Zhang, Hongzhi (Shandong University); Šavija, B. (TU Delft Materials and Environment)","","2023","The performance of engineered cementitious composites (ECCs) under coupled salt freezing and loaded conditions is important for its application on the transportation infrastructure. However, in most of the studies, the specimens were generally loaded prior to the freezing. The influence of sustained load was merely considered. To this end, four sustained deflection levels, i.e., 0%, 10%, 30% and 50% of the deflection at the ultimate flexural strength, and three salt concentrations (1%, 3% and 5%) were applied. Prior to the salt frost resistance test, the fluid absorption of ECC specimens under various conditions were measured. The changes in relative dynamic elastic modulus (RDEM) during the freeze–thaw cycles were captured. The depth and the content profile of free chloride were measured after the coupled sustained load and freezing and thawing cycles. It is shown that 3% NaCl solution leads to the largest deterioration in all cases. There is no visible flaking or damage occurring on the surface. The relationships between locally sustained flexural stress and RDEM loss and also locally sustained flexural stress and free chloride penetration depth were proposed and showed satisfactory results. It is concluded that when ECC is subjected to the FTCs under 1% de-ice salt solution, no depassivation of the steel is expected even under a large deflection level. In terms of 3% and 5% salt solution, the thickness of cover should be no less than 20 mm when a deflection level of 0.5 is applied.","chloride penetration depth; engineered cementitious composites (ECCs); free chloride profile; salt frost; sustained flexural load","en","journal article","","","","","","","","","","","Materials and Environment","","",""
"uuid:83a9312f-ba78-4da9-bbc9-ceca05363b5b","http://resolver.tudelft.nl/uuid:83a9312f-ba78-4da9-bbc9-ceca05363b5b","An operational simulation framework for modelling the multi-interaction of two-wheelers on mixed-traffic road segments","Ni, Ying (Tongji University); Li, Y. (TU Delft Transport and Planning; Tongji University); Yuan, Y. (TU Delft Transport and Planning); Sun, Jian (Tongji University)","","2023","In recent years, the interest in riding in cities using the two-wheeler (e.g., bicycles, electric bicycles, electric mopeds, etc.) increases. Mixed-traffic road segments are one of the most common traffic scenes where the mixed two-wheeler flows exist. Because the movements are often not restricted by lanes, the two-wheeler uses lateral road space more freely and shows obvious multilateral interactions (i.e. multi-interaction) with others, bringing issues that endanger traffic safety. A precise estimation of its impacts on traffic operation and safety is necessary, while the microscopic simulation model can satisfy the need as a helpful tool. However, most existing simulation models of these three types of two-wheelers are essentially focusing on handling the one-on-one interaction. The capability to deal with the two-wheeler multi-interaction in mixed traffic is still rare, and the description of what endogenous tasks are contained by the multi-interaction has also not given by literature. To this end, this paper first defines what the multi-interaction entails on the operational behaviour level, claiming that it contains three intertwined processes, namely a (mental) perception, a (mental) decision, and a physical process. The (mental) perception and decision processes represent the recognition of interactions and the response to traffic conditions, while the physical process refers to the execution of these mental activities. A three-layer simulation framework has then been developed, where each layer sequentially corresponds to one of the operational behaviour tasks. Integrated component models are also proposed in each layer to cover these operational tasks. A Comfort Zone model is hence put forward to dynamically perceive the multiple interactive road users, while a Bayesian network model is developed to deal with the decision-making process under multi-interaction situations. Meanwhile, a behaviour force model is also proposed to capture the non-lane based movements following the selected behaviour and current interaction states. Finally, we face validate the proposed models by the comparison between simulation results and observations obtained from trajectory dataset. Results indicate the model performance matches the observed interaction and motion well.","Bayesian network; Comfort zone; Mixed bicycle flow; Multi-interaction; Operational behaviour; Three-layer framework","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.","","2023-07-01","","","Transport and Planning","","",""
"uuid:a8aa3d0f-5f61-45c1-82c2-6232fc752bb6","http://resolver.tudelft.nl/uuid:a8aa3d0f-5f61-45c1-82c2-6232fc752bb6","Codon-specific KRAS mutations predict survival benefit of trifluridine/tipiracil in metastatic colorectal cancer","van de Haar, Joris (Netherlands Cancer Institute); Ma, Xuhui (Netherlands Cancer Institute); Ooft, Salo N. (Netherlands Cancer Institute); van der Helm, Pim W. (Netherlands Cancer Institute); Hoes, Louisa R. (Netherlands Cancer Institute); Mainardi, Sara (Netherlands Cancer Institute); Pinato, David J. (University of Piemonte Orientale; Imperial College Healthcare NHS Trust; Imperial College London); Sun, Kristi (Imperial College Healthcare NHS Trust); Wessels, L.F.A. (TU Delft Pattern Recognition and Bioinformatics)","","2023","Genomics has greatly improved how patients with cancer are being treated; however, clinical-grade genomic biomarkers for chemotherapies are currently lacking. Using whole-genome analysis of 37 patients with metastatic colorectal cancer (mCRC) treated with the chemotherapy trifluridine/tipiracil (FTD/TPI), we identified KRAS codon G12 (KRASG12) mutations as a potential biomarker of resistance. Next, we collected real-world data of 960 patients with mCRC receiving FTD/TPI and validated that KRASG12 mutations were significantly associated with poor survival, also in analyses restricted to the RAS/RAF mutant subgroup. We next analyzed the data of the global, double-blind, placebo-controlled, phase 3 RECOURSE trial (n = 800 patients) and found that KRASG12 mutations (n = 279) were predictive biomarkers for reduced overall survival (OS) benefit of FTD/TPI versus placebo (unadjusted interaction P = 0.0031, adjusted interaction P = 0.015). For patients with KRASG12 mutations in the RECOURSE trial, OS was not prolonged with FTD/TPI versus placebo (n = 279; hazard ratio (HR) = 0.97; 95% confidence interval (CI) = 0.73–1.20; P = 0.85). In contrast, patients with KRASG13 mutant tumors showed significantly improved OS with FTD/TPI versus placebo (n = 60; HR = 0.29; 95% CI = 0.15–0.55; P < 0.001). In isogenic cell lines and patient-derived organoids, KRASG12 mutations were associated with increased resistance to FTD-based genotoxicity. In conclusion, these data show that KRASG12 mutations are biomarkers for reduced OS benefit of FTD/TPI treatment, with potential implications for approximately 28% of patients with mCRC under consideration for treatment with FTD/TPI. Furthermore, our data suggest that genomics-based precision medicine may be possible for a subset of chemotherapies.","","en","journal article","","","","","","","","","","","Pattern Recognition and Bioinformatics","","",""
"uuid:16c38df9-5825-4c85-a8e2-72f20bcce72f","http://resolver.tudelft.nl/uuid:16c38df9-5825-4c85-a8e2-72f20bcce72f","Combustion Air Humidification for NOx Emissions Reduction in Gas Boiler: An Experimental Study","Zhang, Qunli (Beijing University of Civil Engineering & Architecture; Collaborative Innovation Center of Energy Conservation & Emission Reduction and Sustainable Urban-Rural Development, Beijing); Zhao, Wenqiang (Beijing University of Civil Engineering & Architecture; Collaborative Innovation Center of Energy Conservation & Emission Reduction and Sustainable Urban-Rural Development, Beijing); Sun, Donghan (Beijing University of Civil Engineering & Architecture; Collaborative Innovation Center of Energy Conservation & Emission Reduction and Sustainable Urban-Rural Development, Beijing); Meng, Xiangzhao (Xi’an Jiaotong University); Hooman, K. (TU Delft Process and Energy); Yang, Xiaohu (Xi’an Jiaotong University)","","2023","NOx emission reduction from gas boilers has become a key issue in improving air quality. Combustion air humidification technology is gradually being used to reduce NOx emissions. However, the NOx emission reduction effect of gas boilers at a higher combustion air humidity has been studied less. A flue gas with low NOx emissions and a waste heat recovery system using combustion air humidification technology are proposed in this study. In the ultra-low NOx mode, the effect of high combustion air humidity on NOx emission reduction and efficiency of the gas boiler were studied experimentally. In the waste heat recovery mode, the effects of the heat network backwater temperature on the NOx emission reduction and system efficiency were studied experimentally. Results showed that an increase in air humidity can significantly reduce the NOx concentration formed by combustion. The ultra-low NOx mode reduces NOx emissions from 130 mg/m3 to 23.3 mg/m3 and affects the boiler efficiency slightly. In the waste heat recovery mode, NOx emissions can be reduced to 39.9 mg/m3 when the backwater temperature of the heat network is 55 °C. This condition improves the efficiency to 93.8%. The analysis results provide suggestions for the selection of the operation modes.","","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.","","2023-08-01","","Process and Energy","","","",""
"uuid:8c838630-eda1-44d2-808d-2367650286c9","http://resolver.tudelft.nl/uuid:8c838630-eda1-44d2-808d-2367650286c9","Interpretation of the early stiffening process in alkali-activated slag pastes","Sun, Yubo (Universiteit Gent); Miranda de Lima Junior, L.C. (TU Delft Materials and Environment); Rossi, Laura (Karlsruhe Institut für Technologie); Jiao, Dengwu (Universiteit Gent); Li, Z. (TU Delft Materials and Environment); Ye, G. (TU Delft Materials and Environment; Universiteit Gent); De Schutter, Geert (Universiteit Gent)","","2023","To better understand early stiffening of AAS pastes, distinctive microstructural features by varying the silicate modulus (Ms) have been visualized with in-situ microscopy. In addition, the activation reaction was monitored with multiple approaches, while solid and liquid phases in hydrating AAS were characterized separately. In silicate-activated AAS, it was found fine granules of reaction products are intensively dispersed in the activator solution, leading to a less flocculated system. Compared to hydroxide-activated AAS, the development of interparticle connections was limited at early ages, whereas reaction products were detected with much smaller grain size, less crystalline phase, and higher Al incorporation. Results indicate that the stiffening of hydroxide-activated AAS is attributed to the formation of a well-percolated network through solid reaction products. Instead, massive fine granules of reaction products dispersed in the pore solution continuously develop, which may intensify the interparticle interactions and macroscopically results in the stiffening of a silicate-activated AAS.","Alkali-activated slag; Early stiffening; Microstructure; Reaction products; Rheology","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.","","2023-08-09","","","Materials and Environment","","",""
"uuid:6099cc55-2f01-410a-b52e-24e173e28c0e","http://resolver.tudelft.nl/uuid:6099cc55-2f01-410a-b52e-24e173e28c0e","Tailoring the flow properties of inhaled micronized drug powders by atomic and molecular layer deposition","Zhang, F. (TU Delft ChemE/Product and Process Engineering; Qingyuan Innovation Laboratory, Quanzhou); Wu, K. (TU Delft ChemE/Product and Process Engineering); La Zara, D. (TU Delft ChemE/Product and Process Engineering); Sun, F. (TU Delft ChemE/Product and Process Engineering); Quayle, Michael J. (Operations); Petersson, Gunilla (Operations); Folestad, Staffan (Operations); Chew, Jia Wei (Nanyang Technological University); van Ommen, J.R. (TU Delft ChemE/Product and Process Engineering)","","2023","For dry powder inhaled formulations, good flow behaviour is vital in re-dispersing the powder. However, inhaled drug powders with a particle size below 10 µm are classified as highly cohesive materials with poor flow characteristics. Here we demonstrate how to alter the flow properties of micronized budesonide powders by depositing different materials (organic, inorganic, and hybrid organic–inorganic) in the forms of nanoscale films onto the drug particles using atomic/molecular layer deposition (ALD/MLD) coatings. The angle of repose (static) and pneumatic delivery measurements were performed to access the flow characteristics. The flowability can be effectively improved with the growth of inorganic nanofilm (SiO2, TiO2, or Al2O3) via ALD and hybrid nanofilm (titanicone) via combined ALD-MLD coating. This improvement is reflected by the decrease in the angle of repose and minimum pick-up velocity (Upu), as well as promoting the pneumatic delivery of a much larger amount of drug powders after ALD or hybrid coating. In contrast, the organic PET coated budesonide via MLD exhibits comparable poor flow characteristics as the uncoated budesonide. Rather than being transported in individual particles, the uncoated or PET-coated budesonide powders are pneumatically delivered in form of complex clusters with a size of over 500 μm, whereas the ALD budesonide is dispersed in form of small agglomerates (<100 μm). Despite the difference in agglomerate size, entraining behaviors of all samples agree well with the prediction of Kalman's pick-up Zone I correlation. The inorganic nanofilm deposited via ALD alters the surface chemistry to reduce the inter-particle forces measured by atomic force microscopy, giving rise to an improved drug delivery performance. Nanoscale surface modification of dry powder particles has good potential for inhaled drug delivery enhancement.","atomic layer deposition; drug powders; flowability; molecular layer deposition","en","journal article","","","","","","","","","","","ChemE/Product and Process Engineering","","",""
"uuid:bcd84aae-c688-43b7-a41a-6744cffa8bc1","http://resolver.tudelft.nl/uuid:bcd84aae-c688-43b7-a41a-6744cffa8bc1","Polynomial Chaos Expansion-Based Enhanced Gaussian Process Regression for Wind Velocity Field Estimation from Aircraft-Derived Data","Marinescu, M. (TU Delft Control & Simulation; Universidad Rey Juan Carlos); Olivares, Alberto (Universidad Rey Juan Carlos); Staffetti, Ernesto (Universidad Rey Juan Carlos); Sun, Junzi (TU Delft Control & Simulation)","","2023","This paper addresses the problem of spatiotemporal wind velocity field estimation for air traffic management applications. Using data obtained from aircraft, the eastward and northward components of the wind velocity field inside a specific air space are calculated as functions of time. Both short-term wind velocity field forecasting and wind velocity field reconstruction are performed. Wind velocity data are indirectly obtained from the states of the aircraft flying in the relevant airspace, which are broadcast by the ADS-B and Mode-S aircraft surveillance systems. The wind velocity field is estimated by combining two data-driven techniques: the polynomial chaos expansion and the Gaussian process regression. The former approximates the global behavior of the wind velocity field, whereas the latter approximates the local behavior. The eastward and northward wind components of the wind velocity field must be estimated, which causes the problem to be a multiple-output problem. This method enables the estimation of the wind velocity field at any spatiotemporal location using wind velocity observations from any spatiotemporal location, eliminating the need for spatial and temporal grids. Moreover, since the method proposed in this article allows for the probability distributions of the estimates to be computed, it causes the computation of the confidence intervals to be possible. Furthermore, since the method presented in this paper allows for data assimilation, it can be used online to continuously update the wind velocity field estimation. The method is tested on different wind scenarios and different training-test data configurations, by means of which the consistency between the results of the wind velocity field forecasting and the wind velocity field reconstruction is checked. Finally, the ERA5 meteorological reanalysis data of the European Centre for Medium-Range Weather Forecasts are used to validate the proposed technique. The results show that the method is able to reliably estimate the wind velocity field from aircraft-derived data.","ADS-B; air traffic management; Gaussian process regression; Mode S; polynomial chaos expansion; wind velocity field estimation","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:c2210e62-90e3-4879-a1cc-7cf509199dad","http://resolver.tudelft.nl/uuid:c2210e62-90e3-4879-a1cc-7cf509199dad","A novel supply chain network evolving model under random and targeted disruptions","Wang, Jiepeng (Beihang University; Beijing Key Laboratory of Emergency Support Simulation Technologies for City Operations); Zhou, Hong (Beihang University; Beijing Key Laboratory of Emergency Support Simulation Technologies for City Operations); Sun, Xinlei (Nanjing University of Aeronautics and Astronautics); Yuan, Y. (TU Delft Transport and Planning)","","2023","Due to the fact that there is a lack of comprehensive understanding of how the dynamic nature of supply chain networks (SCNs) interrelates with network structures, particularly network topologies under disruptions. This research employs a novel evolving model of a supply chain network (SCNE model) by modifying the Barabási and Albert (BA) model to capture the phenomenon of regional economy and the factor of firms’ attractiveness, considering the degree, the locality preference, and the heterogeneity of SCN members simultaneously. We then analyze the SCNE model via the mean-field theory and conduct simulation study to identify the scale-free characteristic of the proposed supply chain network model. Additionally, we leverage node and edge removal to emulate random and targeted disruptions. We measure and compare the robustness of four network models, i.e., the SCNE model, the Erdos and Rényi (ER) model, the BA model, and the Watts and Strogatz (WS) model using two essential metrics, i.e., the size of the largest connected component and the network efficiency. We find that the robustness of the SCNE model is better than the BA model and the WS model on the whole in the presence of disruptions. Also, from the node level, the SCNE model maintains resilience, behaving similarly to the ER model against random disruptions while it shows vulnerability under targeted disruptions, responding in line with the BA model and the WS model. From the edge level, the network efficiency of the SCNE model changes slowly, and the topological structure of the SCNE model slightly changes initially but decreases rapidly at some value, as well as the BA model, the WS model, and the ER model. Based on the results, we summarize key points of the implications for research and practice in supply chain management.","Complex network; Robustness; Simulation; Supply chain disruptions; Supply chain management","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.","","2023-09-27","","","Transport and Planning","","",""
"uuid:7a5919f9-3b2d-4d34-87d9-71f656dd0133","http://resolver.tudelft.nl/uuid:7a5919f9-3b2d-4d34-87d9-71f656dd0133","Prediction & optimization of alkali-activated concrete based on the random forest machine learning algorithm","Sun, Yubo (Universiteit Gent); Cheng, H. (TU Delft Concrete Structures); Zhang, Shizhe (TU Delft Materials and Environment); Mohan, Manu K. (Universiteit Gent); Ye, G. (TU Delft Materials and Environment; Universiteit Gent); De Schutter, Geert (Universiteit Gent)","","2023","Alkali-activated concrete (AAC) is regarded as a promising alternative construction material to reduce the CO2 emission induced by Portland cement (PC) concrete. Due to the diversity in raw materials and complexity of reaction mechanisms, a commonly applied design code is still absent to date. This study attempts to directly correlate the AAC mix design parameters to their performances through an artificial intelligence approach. To be specific, 145 fresh property data and 193 mechanical strength data were collected from laboratory tests on 52 AAC mixtures, which were used as inputs for the machine learning algorithm. Five independent random forest (RF) models were established, which are able to predict fresh and hardened properties (in terms of compressive strength, slump values, static/dynamic yield stress, and plastic viscosity) of AAC with equivalent accuracy reported in the literature. Moreover, an inverse optimization was performed on the RF model obtained to reduce the sodium silicate dosages, which may further mitigate the environmental impact of producing AAC. The present RF model gives practical information on AAC mix design cases.","Alkali-activated concrete; Machine learning; Mix design; Optimization; Prediction; Random forest","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.","","2023-10-27","","","Concrete Structures","","",""
"uuid:3a284b23-35dc-4aeb-af4f-023478725ca9","http://resolver.tudelft.nl/uuid:3a284b23-35dc-4aeb-af4f-023478725ca9","A mix design methodology of blast furnace slag and fly ash-based alkali-activated concrete","Sun, Beibei (Universiteit Gent); Sun, Yubo (Universiteit Gent); Ye, G. (TU Delft Materials and Environment; Universiteit Gent); De Schutter, Geert (Universiteit Gent)","","2023","Although the application of blast furnace slag and fly ash-based alkali-activated concrete (BFS/FA-AAC) has both economic and environmental benefits, it is limited by the lack of a straightforward mix design method. In this paper, an experiment was conducted to investigate the effect of control factors, including the Na2O/binder ratio, the SiO2/Na2O ratio, the BFS/binder ratio, the water/binder ratio, and the water content on the workability (slump and rheology) of BFS/FA-AAC, and the effect of control factors include the Na2O/binder ratio, the SiO2/Na2O ratio, the BFS/binder ratio, the water/binder ratio, and the curing time on the compressive strength of BFS/FA-AAC. As a result, the influence degree and mechanism of each control factor on the performance of BFS/FA-AAC were quantitively explored and the accuracy of an empirical compressive strength formula was validated. Based on that, a practical mix design method of BFS/FA-AAC was eventually established. It is found that the mixture composition and content of paste can significantly influence the workability of BFS/FA-AAC. The compressive strength of BFS/FA-AAC is determined by control factors when the water content is within 160–195 kg/m3. The mechanical predictive method of BFS/FA-AAC is proven of high accuracy. The mixture designed by this methodology exhibits satisfied fresh and hardened performance as well as high environmental benefits.","Mix design; Rheology; Slag and fly ash-based alkali-activated concrete; Slump; Strength","en","journal article","","","","","","","","","","","Materials and Environment","","",""
"uuid:fac3153f-e987-4ae2-88ed-8460b3d54735","http://resolver.tudelft.nl/uuid:fac3153f-e987-4ae2-88ed-8460b3d54735","Deep reinforcement learning control approach to mitigating actuator attacks","Wu, C. (Harbin Institute of Technology); Pan, W. (TU Delft Robot Dynamics; The University of Manchester); Staa, Rick (Student TU Delft); Liu, Jianxing (Harbin Institute of Technology); Sun, Guanghui (Harbin Institute of Technology); Wu, Ligang (Harbin Institute of Technology)","","2023","This paper investigates the deep reinforcement learning based secure control problem for cyber–physical systems (CPS) under false data injection attacks. We describe the CPS under attacks as a Markov decision process (MDP), based on which the secure controller design for CPS under attacks is formulated as an action policy learning using data. Rendering the soft actor–critic learning algorithm, a Lyapunov-based soft actor–critic learning algorithm is proposed to offline train a secure policy for CPS under attacks. Different from the existing results, not only the convergence of the learning algorithm but the stability of the system using the learned policy is proved, which is quite important for security and stability-critical applications. Finally, both a satellite attitude control system and a robot arm system are used to show the effectiveness of the proposed scheme, and comparisons between the proposed learning algorithm and the classical PD controller are also provided to demonstrate the advantages of the control algorithm designed in this paper.","Cyber–physical systems; Deep reinforcement learning; False data injection attacks; Lyapunov stability","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.","","2023-09-17","","","Robot Dynamics","","",""
"uuid:9e2e7839-1a5b-44f4-a0b4-459503af7b65","http://resolver.tudelft.nl/uuid:9e2e7839-1a5b-44f4-a0b4-459503af7b65","CO2 utilization in chemical looping gasification and co-gasification of lignocellulosic biomass components over iron-based oxygen carriers: Thermogravimetric behavior, synergistic effect, and reduction characteristics","Kuo, Po Chih (University of Tokyo); Sun, Zhuang (University of Tokyo); Özdemir, F. (TU Delft Energy Technology); Aziz, Muhammad (University of Tokyo); Wu, Wei (National Cheng Kung University)","","2023","Efficient CO2 utilization in the thermochemical conversion of biomass plays an important role in creating a future low-carbon economy. This study attempts to explore the CO2-assisted chemical looping gasification and co-gasification process of lignocellulosic biomass components (hemicellulose, cellulose, and lignin) with iron oxide oxygen carriers using thermogravimetry and differential thermal analysis. Three different iron oxide oxygen carrier-to-biomass (O/B) ratios were taken into account to deeply understand the thermal degradation characteristics of individual components (O/B ratio: 0) and their blending with iron oxide oxygen carriers (O/B ratio: 0.5 and 1). Meanwhile, the reduction characteristics of three major biomass components were also investigated in terms of X-ray diffraction (XRD), synergistic interaction, and reduction degree. Experimental results suggest that the existence of iron oxide oxygen carriers could accelerate the reaction kinetics under the reactive CO2 environment, arising from the competitive relationship between the direct reduction reaction by char in biomass and the Boudouard reaction at high temperatures (600–950 °C). Interestingly, the reoxidation behavior of the reduced iron oxide is observed at high temperatures, especially for lignin. Among all the tested biomass materials, their ability to reduce iron oxide oxygen carriers under the CO2 atmosphere follows the order of biomass mixture (1:1:1 wt%)>lignin>xylan>cellulose. Moreover, the findings indicate that significant synergistic interaction exists during the CO2-assisted chemical looping co-gasification process.","Chemical looping gasification; CO utilization; Lignocellulosic biomass; Reduction characteristics; Synergistic effect; TGA","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.","","2023-10-20","","","Energy Technology","","",""
"uuid:1ce5eb47-7501-49fe-8709-81fc0258b23c","http://resolver.tudelft.nl/uuid:1ce5eb47-7501-49fe-8709-81fc0258b23c","On the quantitative resilience assessment of complex engineered systems","Yang, M. (TU Delft Safety and Security Science; Universiti Teknologi Malaysia; University of Tasmania); Sun, H. (TU Delft Safety and Security Science; China University of Petroleum (East China)); Geng, S. (TU Delft Safety and Security Science; Nanjing University of Aeronautics and Astronautics)","","2023","Recent years have seen the increasing complexity of engineered systems. Complexity and uncertainty also exist in engineered systems’ interactions with human operators, managers, and the organization. Resilience, focusing on a system's ability to anticipate, absorb, adapt to, and recover from disruptive situations, can provide an umbrella concept that covers reliability and risk-based thinking to ensure these complex systems' safety. This paper discusses the quantitative aspects of the notion of resilience. Like the quantitative risk assessment framework, a generic framework should be developed for quantitative resilience assessment. This paper proposes a framework based on a triplet resilience definition consisting of disruption, functionality, and performance. Uncertainty treatment is also considered. The proposed framework aims to answer the question of “resilience of what to what” and how it can be quantitively assessed.","Complex system; Quantitative assessment; Resilience; Safety; Uncertainty","en","journal article","","","","","","","","","","","Safety and Security Science","","",""
"uuid:b16f042c-06ef-4b71-84ea-f266c42e4ee2","http://resolver.tudelft.nl/uuid:b16f042c-06ef-4b71-84ea-f266c42e4ee2","Erratum: Electrical characteristics and photodetection mechanism of TiO2/AlGaN/GaN heterostructure-based ultraviolet detectors with a Schottky junction (J. Mater. Chem. C (2023) 11 (1704–1713) DOI: 10.1039/D2TC04491A)","Zhan, Teng (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Sun, Jianwen (Tsinghua University); Feng, Tao (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Zhang, Yulong (Tsinghua University); Zhou, Binru (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Zhang, Banghong (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Wang, Junxi (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Sarro, Pasqualina M (TU Delft Electronic Components, Technology and Materials); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2023","The authors regret an error in the abstract of the published article: the text ‘‘(i) the Schottky emission mechanism at a low reverse voltage (0–1 V) before the current is fully turned on.’’ should be changed to ‘‘(i) the Schottky emission mechanism at a low reverse voltage (0 to 1 V) before the current is fully turned on.’’ This change does not affect the main conclusions of the manuscript. The authors would like to apologize for any inconvenience caused. The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.","","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:9a59a549-339f-4469-86d7-3b7ed60e8b48","http://resolver.tudelft.nl/uuid:9a59a549-339f-4469-86d7-3b7ed60e8b48","A Secure Robot Learning Framework for Cyber Attack Scheduling and Countermeasure","Wu, Chengwei (Harbin Institute of Technology); Yao, Weiran (Harbin Institute of Technology); Luo, Wensheng (Harbin Institute of Technology); Pan, W. (TU Delft Robot Dynamics; The University of Manchester); Sun, Guanghui (Harbin Institute of Technology); Xie, Hui (Harbin Institute of Technology); Wu, Ligang (Harbin Institute of Technology)","","2023","The problem of learning-based control for robots has been extensively studied, whereas the security issue under malicious adversaries has not been paid much attention to. Malicious adversaries can invade intelligent devices and communication networks used in robots, causing incidents, achieving illegal objectives, and even injuring people. This article first investigates the problems of optimal false data injection attack scheduling and countermeasure design for car-like robots in the framework of deep reinforcement learning. Using a state-of-the-art deep reinforcement learning approach, an optimal false data injection attack scheme is proposed to deteriorate the tracking performance of a robot, guaranteeing the tradeoff between the attack efficiency and the limited attack energy. Then, an optimal tracking control strategy is learned to mitigate attacks and recover the tracking performance. More importantly, a theoretical stability guarantee of a robot using the learning-based secure control scheme is achieved. Both simulated and real-world experiments are conducted to show the effectiveness of the proposed schemes.","Deep reinforcement learning; optimal attack scheduling; robot; secure control","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.","","2023-12-05","","","Robot Dynamics","","",""
"uuid:a54db7b5-b20e-4b98-8fb0-290739839170","http://resolver.tudelft.nl/uuid:a54db7b5-b20e-4b98-8fb0-290739839170","Rational design and additive manufacturing of grain boundary-inspired, multi-architecture lattice structures","Yang, J. (TU Delft Biomaterials & Tissue Biomechanics; Chongqing University); Chen, Xiaohong (Chongqing University; Northwestern Polytechnical University); Sun, Yuanxi (Chongqing University); Feng, Chen (Chongqing University); Yang, Zheng (Chongqing University); Zadpoor, A.A. (TU Delft Biomaterials & Tissue Biomechanics); Mirzaali, Mohammad J. (TU Delft Biomaterials & Tissue Biomechanics); Bai, Long (Chongqing University)","","2023","The advent of additive manufacturing has facilitated the design and fabrication of hybrid lattice structures with multiple morphologies. These structures combine multiple distinct architectures into a single structure with an exceptional performance that far exceeds that of each constituting architecture. However, combining strut-based lattices poses serious challenges in establishing effective connections, primarily due to complications in formulating mathematical expressions. Here, we introduce a novel approach, inspired by the connections observed in the grain boundaries of polycrystalline materials, to design the interconnections of hybrid structures. This strategy involves shrinking the unit cell linkage, thereby addressing the difficulty of forming efficient connections at arbitrary spatial interfaces within strut-based lattice structures. We then use the relevant design theories to tune the performance of these connections and simplify the design process for hybrid structures – even for inexperienced designers. Our experimental observations confirm the efficacy of the proposed strategy, bridging the knowledge gap in the design of connected strut-based multi-lattice structures. Furthermore, this approach enhances the design of tailored hybrid structures and fosters the development of metamaterials with advanced, unique functionalities. The proposed approach has important implications for the development of designer materials, with applications in medical devices, (soft) robotics, and implants.","Additive manufacturing; Hybrid structures; Mechanical metamaterials; Multi-architecture lattices","en","journal article","","","","","","","","","","","Biomaterials & Tissue Biomechanics","","",""
"uuid:9ea72dd0-f5bd-454e-8d40-3db386a148bd","http://resolver.tudelft.nl/uuid:9ea72dd0-f5bd-454e-8d40-3db386a148bd","Contrail minimization through altitude diversions: A feasibility study leveraging global data","Roosenbrand, E.J. (TU Delft Control & Simulation); Sun, Junzi (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2023","As global flight volume rises, the aviation industry is facing increasing climate challenges. One major factor is the impact of contrails, which trap outgoing terrestrial radiation and counteract emission reduction benefits from emission-optimized flight routes. Our study quantifies contrail-forming flights globally and assesses altitude adjustments necessary to avoid these regions. Using the Integrated Global Radiosonde Archive and global flight data from 2021-2022, we highlight several contrail-prone regions with high air traffic volumes and high potential for contrail-formation. We propose an operational strategy in altitude diversion, which can halve the amount of persistent contrails. Further, we analyse the additional carbon emissions caused by the altitude diversions and safety risks in terms of potential new conflicts. Our findings provide actionable strategies for policymakers to balance climate mitigation and operational challenges in aviation.","Aircraft surveillance data; Atmospheric science; Contrails; OpenSky; Remote sensing; Sustainability","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:44b6e88c-d049-4b5f-9d0d-7a42775f77a4","http://resolver.tudelft.nl/uuid:44b6e88c-d049-4b5f-9d0d-7a42775f77a4","A state-of-the-art review on rolling resistance of asphalt pavements and its environmental impact","Sun, Z. (TU Delft Pavement Engineering); Wagasing Arachchige, W.A.A.S. (TU Delft Pavement Engineering); Anupam, K. (TU Delft Pavement Engineering); Kasbergen, C. (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering)","","2023","In the context of climate change and global warming, the attention on the environmental cost of pavements is increasing. To scientifically quantify the environmental cost of pavements, accurate prediction of rolling resistance and fuel consumption is important. In this paper, a comprehensive review on rolling resistance of asphalt pavements and its environmental impact was presented. At first, the commonly used definitions of rolling resistance and texture characterisation methods of pavement surface were introduced. Then, the influence of different factors on rolling resistance was discussed. Next, the measuring and modelling approaches of rolling resistance were reviewed. At last, methods which can be used to predict fuel consumption and environmental impact were presented. It was found that an ideal approach for texture characterisation of pavement surface is to make use of the entire wavelength spectrum of road profiles and consider the enveloping curve of tire treads. Furthermore, the fact that rolling resistance can be influenced by different factors introduces difficulties in accurate measurement and modelling of rolling resistance. Moreover, testing methods and conditions have a significant effect on the empirical modelling of rolling resistance, while it is difficult and time-consuming to consider all the energy loss in the computational modelling of rolling resistance. In addition, the prediction of fuel consumption and environmental impact highly depends on the formulating methods and measuring conditions. The work presented in this paper will help to gain more insight into rolling resistance and its environmental impact, which ultimately promotes the construction of environmentally friendly pavements.","Asphalt pavement; Environmental impact; Fuel consumption; Rolling resistance; Surface texture","en","review","","","","","","","","","","","Pavement Engineering","","",""
"uuid:22a430ac-c946-42ee-8446-4098b4f0c337","http://resolver.tudelft.nl/uuid:22a430ac-c946-42ee-8446-4098b4f0c337","Modelling the time-dependent mechanical behaviour of clay rocks based on meso- and micro-structural viscous properties","Sun, Yufeng (Université de Lyon); Pardoen, Benoît (Université de Lyon); van den Eijnden, A.P. (TU Delft Geo-engineering); Wong, Henry (Université de Lyon)","","2023","Clay rocks are multiphase porous media having a complex structure and behaviour characterised by heterogeneity, damage and viscosity, existing on a wide range of scales. The mesoscopic scale of mineral inclusions embedded in a clay matrix has an important role in the mechanisms of deformation under mechanical loading by cracking and creeping. This study introduces a micromechanical approach to model the time-dependent mechanical behaviour of clay rocks. A heterogeneous clay rock is represented at the mesoscopic scale as a composite material consisting of rigid elastic mineral inclusions (quartz, calcite and pyrite) embedded in a clay matrix. To describe the damageable rock behaviour and its failure modes at the small scale, interfaces between different mineral phases and within the clay matrix are considered. Viscous effects are incorporated inside the clay aggregates, with intergranular microfractures propagating in the clay matrix, in order to investigate their contribution to the creep behaviour of clay rock at the macroscale. The mesostructure of the clay rock is represented in digital 2D Representative Elementary Areas (REAs). The overall mesoscale behaviour of the clay rock under mechanical solicitation is numerically obtained from the REA by computational homogenisation within a two-scale finite element squared framework. Then, the model is validated at mesoscale against experimental data. The variability of the material response and the time evolution of the mineral interfacial damage state are investigated in relation to the small-scale properties and failure, while considering mesostructure variability. The results can give some valuable insights into creep behaviour of the clay rock from a small-scale perspective.","clay rock; creep; microstructural variability; multiscale numerical model; viscosity","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.","","2024-03-07","","","Geo-engineering","","",""
"uuid:87905f6e-2d35-460c-8f95-1f585f3ff97c","http://resolver.tudelft.nl/uuid:87905f6e-2d35-460c-8f95-1f585f3ff97c","Fast Loss of Effectiveness Detection on a Quadrotor using Onboard Sensors and a Kalman Estimation Approach","Van Schijndel, B. A.Strack (Student TU Delft); Sun, S. (TU Delft Control & Simulation); de Visser, C.C. (TU Delft Control & Simulation)","","2023","This paper presents a novel method for fast and robust detection of actuator failures on quadrotors. The proposed algorithm has very little model dependency. A Kalman estimator estimates a stochastic effectiveness factor for every actuator, using only onboard RPM, gyro and accelerometer measurements. Then, a hypothesis test identifies the failed actuator. This algorithm is validated online in real-time, also as part of an active fault tolerant control system. Loss of actuator effectiveness is induced by ejecting the propellers from the motors. The robustness of this algorithm is further investigated offline over a range of parameter settings by replaying real flight data containing 26 propeller ejections. The detection delays are found to be in the 30∼130 ms range, without missed detections or false alarms occurring.","","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.","","2024-02-05","","","Control & Simulation","","",""
"uuid:2c87ac8b-2e7e-4889-9747-dc3181a34a16","http://resolver.tudelft.nl/uuid:2c87ac8b-2e7e-4889-9747-dc3181a34a16","Optimal Sub-References for Setpoint Tracking: A Multi-level MPC Approach","Sun, D. (TU Delft Transport and Planning); Jamshidnejad, A. (TU Delft Control & Simulation); De Schutter, B.H.K. (TU Delft Delft Center for Systems and Control)","","2023","We propose a novel method to improve the convergence performance of model predictive control (MPC) for setpoint tracking, by introducing sub-references within a multilevel MPC structure. In some cases, MPC is implemented with a short prediction horizon due to limited on-line computation capacity, which could lead to deteriorated dynamic performance. The introduced multi-level optimization method can generate proper sub-references for the MPC setpoint tracking problem, and efficiently improve the dynamic performance. In the higher level a specific performance criterion is taken as the objective, while explicit MPC is utilized in the lower level to represent the control input. The generated sub-references are then used in MPC for the real system with prediction horizon restrictions. Setpoint-tracking MPC for linear systems is used to illustrate the approach throughout the paper. Numerical simulations show that MPC with sub-references significantly improves the convergence performance compared with regular MPC with the same prediction horizon. Thus, it can be concluded that MPC with sub-references has a high potential to tackle more complicated control problems with limited computation capacity.","Model predictive control; setpoint tracking; sub-reference; multi-level MPC","en","journal article","","","","","","","","","","Delft Center for Systems and Control","Transport and Planning","","",""
"uuid:a8f660e0-15de-4a2a-96ed-edd77c54ec01","http://resolver.tudelft.nl/uuid:a8f660e0-15de-4a2a-96ed-edd77c54ec01","Immobilization capacity assessment of a binder from arsenic-containing biohydrometallurgy waste: Effects of halloysite nanotubes and biochar addition","Zhao, Yingliang (The Hong Kong Polytechnic University; Northeastern University); Sun, Yong (Northeastern University); Guo, Z. (TU Delft Rivers, Ports, Waterways and Dredging Engineering; Northeastern University); Sun, Xiaogang (Northeastern University); Qiu, Jingping (Northeastern University)","","2023","The aim of this study was to improve the immobilization capacity of a binder prepared from As-containing biohydrometallurgy waste (BAW) on arsenic (As) by modifying it with halloysite nanotubes (HNTs) and biochar (BC). The study investigated the influence of HNTs and BC on the chemical fractions and leaching characteristics of As, as well as the influence on the compressive strength of BAW. The results indicated that the addition of HNTs and BC effectively decreased As leaching. The presence of 1.0 wt% HNTs decreased the As leaching concentration from 1.08 mg/L to 0.15 mg/L, with the corresponding immobilization rate reaching about 90.9 %. A high amount of BC seemed to show better performance in improving the As immobilization capacity of BAW. However, a strongly reduced early compressive strength of BAW was observed, making it unsuitable to be used as an additive in this situation. The effects of HNTs on the increase of As immobilization capacity of BAW were attributed to two aspects. Firstly, As species were adsorbed onto the surface of HNTs via H-bonds, which was verified via density functional theory calculation. Secondly, the addition of HNTs decreased the pore volume of BAW, leading to a more compact structure, and hence increasing the physical encapsulation capacity for As. Environmental implication: The rational disposal of arsenic-containing biohydrometallurgy waste has always been a top priority for the green and low-carbon development of the metallurgical industry. In this article, we have taken the perspective of large-scale resource utilization of solid waste and pollution control, and developed arsenic-containing biohydrometallurgy waste into a cementitious material, and enhancing arsenic immobilization capacity with the addition of HNTs and BC. This study provides an effective method for the rational disposal of arsenic-containing biohydrometallurgy waste.","As immobilization; Biohydrometallurgy waste; Density function theory; Leaching characteristics","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.","","2023-12-07","","","Rivers, Ports, Waterways and Dredging Engineering","","",""
"uuid:cd05702e-a4ec-437b-981c-cd69042679a3","http://resolver.tudelft.nl/uuid:cd05702e-a4ec-437b-981c-cd69042679a3","Investigation on the effect of interface properties on compressive failure behavior of 3D woven composites through micromechanics-based multiscale damage model","Zheng, T. (TU Delft Structural Integrity & Composites; Harbin Institute of Technology); Guo, Licheng (Harbin Institute of Technology); Sun, Ruijian (Beijing Institute of Astronautical Systems Engineering, Beijing); Wang, Tongtong (Harbin Institute of Technology); Hong, Changqing (Harbin Institute of Technology); Benedictus, R. (TU Delft Structural Integrity & Composites); Pascoe, J.A. (TU Delft Structural Integrity & Composites)","","2023","In this paper, the effect of interface properties on the compressive failure behavior of 3D woven composites (3DWC) is investigated by incorporating a micromechanics-based multiscale damage model (MMDM). The correlation between the mesoscopic stress of yarns and microscopic stress of constituents is established by defining a stress amplification factor. With the microscopic stresses, the fiber breakage and matrix failure can be separately evaluated at the microscale, without assuming the yarns as transversely isotropic homogeneous materials. Especially, the interfacial debonding between yarns and matrix is also a dominant damage mode within 3DWC. Given that there is still a lack of studies on the influence of interfacial properties on the compressive failure behavior of 3DWC, it is meaningful to perform numerical parametric studies to reveal how the interface properties contribute to the damage mechanisms of 3DWC under compressions. The predicted results indicate that with the increase of interface strengths and fracture toughness, the compressive resistance of 3DWC can be significantly improved, resulting in higher strength and failure strain. Additionally, the studied 3DWCs with weak, medium and strong interfaces exhibit different damage development processes.","3D woven composites; Compressive failure behavior; Interface; Micromechanics-based multiscale damage model; Numerical parametric study","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.","","2023-11-29","","","Structural Integrity & Composites","","",""
"uuid:1014a9d2-3604-46ac-a92e-cb6e485e7d72","http://resolver.tudelft.nl/uuid:1014a9d2-3604-46ac-a92e-cb6e485e7d72","DaisyRec 2.0: Benchmarking Recommendation for Rigorous Evaluation","Sun, Zhu (Institute of High Performance Computing); Fang, Hui; Yang, J. (TU Delft Web Information Systems); Qu, Xinghua (Bytedance AI Lab); Liu, Hongyang (Yanshan University); Yu, Di (Singapore Management University); Ong, Yew Soon (Nanyang Technological University); Zhang, Jie (Nanyang Technological University)","","2023","Recently, one critical issue looms large in the field of recommender systems - there are no effective benchmarks for rigorous evaluation - which consequently leads to unreproducible evaluation and unfair comparison. We, therefore, conduct studies from the perspectives of practical theory and experiments, aiming at benchmarking recommendation for rigorous evaluation. Regarding the theoretical study, a series of hyper-factors affecting recommendation performance throughout the whole evaluation chain are systematically summarized and analyzed via an exhaustive review on 141 papers published at eight top-tier conferences within 2017-2020. We then classify them into model-independent and model-dependent hyper-factors, and different modes of rigorous evaluation are defined and discussed in-depth accordingly. For the experimental study, we release DaisyRec 2.0 library by integrating these hyper-factors to perform rigorous evaluation, whereby a holistic empirical study is conducted to unveil the impacts of different hyper-factors on recommendation performance. Supported by the theoretical and experimental studies, we finally create benchmarks for rigorous evaluation by proposing standardized procedures and providing performance of ten state-of-the-arts across six evaluation metrics on six datasets as a reference for later study. Overall, our work sheds light on the issues in recommendation evaluation, provides potential solutions for rigorous evaluation, and lays foundation for further investigation.","Benchmarks; fair comparison; recommender systems; reproducible evaluation; standardized procedures","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.","","2023-06-26","","","Web Information Systems","","",""
"uuid:a6b2f9f5-2a85-46d3-92fd-a097f8a4367c","http://resolver.tudelft.nl/uuid:a6b2f9f5-2a85-46d3-92fd-a097f8a4367c","Mechanical and shape memory properties of NiTi triply periodic minimal surface structures fabricated by laser powder bed fusion","Sun, Lingqi (Huazhong University of Science and Technology); Chen, K. (TU Delft Biomechanical Engineering); Geng, Peng (Huazhong University of Science and Technology); Zhou, Yan (Huazhong University of Science and Technology); Wen, Shifeng (Huazhong University of Science and Technology); Shi, Yusheng (Huazhong University of Science and Technology)","","2023","Porous NiTi lattice structures are widely used in the manufacture of crucial components owing to their excellent shape memory effect, superelasticity, and high damping capacities. However, the specific strength and lightweight characteristics of porous NiTi lattice structures fabricated by conventional technologies are limited by unpredictability. In this work, three types of porous NiTi structures based on triply periodic minimal surface (TPMS) – Diamond, Gyroid, and Primitive – were designed and manufactured by the laser powder bed fusion (LPBF) additive manufacturing process. This work demonstrates LPBF is a feasible and efficient approach to fabricate highly accurate porous NiTi TPMS structures. Moreover, the influence of each of these structures on the mechanical and shape memory properties was investigated. Among the three structures, Gyroid had the smallest volume fraction deviation. Furthermore, the Diamond structure had the largest compressive modulus (782.82 MPa) and ultimate yield strength (163.14 MPa). The Gyroid and Primitive structures exhibit excellent elastic recovery deriving from high values of compressive modulus (662.44 MPa, and 703.29 MPa), and can maintain reliable structural robustness. The Primitive structure exhibited the lowest mechanical properties (37.80 MPa). During the cyclic compression test, Gyroid and Primitive show a smaller unrecovered strain than Diamond. Primitive shows the largest recovered strain during the heating process (6.98%). The higher mechanical flexibility of Primitive structure endows this structure with higher recovery ratio. During the direct compression test, the residual strain exhibits a positive correlation with the loading strain. All three structures exhibit good deformation recovery capability with a strain of 4%. At a strain of 12%, recovered strain during heating became the dominant factor in the recovery of the TPMS structure. Overall, porous NiTi TPMS structures are capable of reversible compressibility composed of rapid elastic recovery and controllable shape memory recovery. The unique performance of porous NiTi TPMS structure fabricated by LPBF renders it a highly efficiency energy-absorbing structure.","Laser powder bed fusion; NiTi alloy; Shape memory effect; Three-period minimum surface","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.","","2024-01-05","","Biomechanical Engineering","","","",""
"uuid:748d1ee6-5b9b-41a8-adfc-588b0306995b","http://resolver.tudelft.nl/uuid:748d1ee6-5b9b-41a8-adfc-588b0306995b","A micro graphene high temperature sensor with a single Si3N4 protective layer","Tang, Chenggang (Beijing Jiaotong University); Zeng, Simei (Beijing Jiaotong University); Hong, H. (TU Delft Electronic Components, Technology and Materials); Fang, Yuan (Beijing Jiaotong University); Li, Yuning (Beijing Jiaotong University); Wang, Yuqiang (Beijing Jiaotong University); Zhu, Mingqiang (Beijing Jiaotong University); Sun, Jingye (Beijing Jiaotong University); Deng, Tao (Beijing Jiaotong University)","","2023","Temperature sensors are widely used in industrial production, national defense and military fields. The traditional temperature sensors normally operate in a limited temperature range no more than 200 °C, which cannot be used for extreme high temperature detections. In this paper, a thermal protection method for the sensing graphene membrane is proposed and a graphene high temperature sensor has been fabricated and investigated. By growing a single silicon nitride (Si3N4) protective layer on top of graphene, our design not only solves the problem that graphene is easily oxidized at high temperature, but also prevents graphene from being polluted by impurities, which would lead to the degradation of graphene performance. We further explore the protective effect of Si3N4 layer with different thicknesses on the performance of the sensor. It has been found that the 400 nm Si3N4 protective layer gives the best protective capability. The sensor exhibits a positive temperature coefficient (PTC) from 50 to 600 °C and a maximal temperature coefficient of resistance (TCR) value of 0.29% °C−1 at 150 °C is achieved. It has been demonstrated that our graphene high temperature sensor with protective layer structure maintains good stability not only at high temperature up to 600 °C, but also over a long-period of time under room temperature. In short, the high temperature sensor possesses a wide temperature measurement range with micro dimensions, a relatively high TCR and a smaller thermal hysteresis. The thermal protection approach proposed in this paper provides a new idea for the fabrication of high temperature pressure sensor, which is expected to be applied in aerospace engines and oil wells, etc.","Graphene high temperature sensor; Long-period stability; Temperature measurement; Thermal protection","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.","","2023-12-18","","","Electronic Components, Technology and Materials","","",""
"uuid:4cf927d9-47c8-4f12-a118-2b7e51b24a2b","http://resolver.tudelft.nl/uuid:4cf927d9-47c8-4f12-a118-2b7e51b24a2b","Designed Multifunctional Spider Silk Enabled by Genetically Encoded Click Chemistry","Jiang, Bojing (The Hong Kong University of Science and Technology; Washington University in St. Louis); Tan, Sin Yen (The Hong Kong University of Science and Technology); Fang, Shiyu (The Hong Kong University of Science and Technology); Feng, Xiaohan (The Hong Kong University of Science and Technology); Park, B.P. (TU Delft ImPhys/Maresca group; The Hong Kong University of Science and Technology); Fok, Hong Kiu Francis (The Hong Kong University of Science and Technology); Yang, Zhongguang (The Hong Kong University of Science and Technology; SPES Tech Limited); Wang, Ri (The Hong Kong University of Science and Technology); Kou, Songzi (Greater Bay Biomedical InnoCenter); Wu, Angela Ruohao (The Hong Kong University of Science and Technology); Sun, Fei (The Hong Kong University of Science and Technology; Greater Bay Biomedical InnoCenter)","","2023","Spider silk is recognized for its exceptional mechanical properties and biocompatibility, making it a versatile platform for developing functional materials. In this study, a modular functionalization strategy for recombinant spider silk is presented using SpyTag/SpyCatcher chemistry, a prototype of genetically encoded click chemistry. The approach involves AlphaFold2-aided design of SpyTagged spider silk coupled with bacterial expression and biomimetic spinning, enabling the decoration of silk with various SpyCatcher-fusion motifs, such as fluorescent proteins, enzymes, and cell-binding ligands. The silk threads can be coated with a silica layer using silicatein, an enzyme for silicification, resulting in a hybrid inorganic–organic 1D material. The threads installed with RGD or laminin cell-binding ligands lead to enhanced endothelial cell attachment and proliferation. These findings demonstrate a straightforward yet powerful approach to 1D protein materials.","biomaterials; cell adhesion; click chemistry; silicification; spider silk","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.","","2023-12-15","","","ImPhys/Maresca group","","",""
"uuid:c1600edf-9d58-4302-9864-5702e568a44e","http://resolver.tudelft.nl/uuid:c1600edf-9d58-4302-9864-5702e568a44e","Chloride penetration resistance of engineered cementitious composite (ECC) subjected to sustained flexural loading","Wang, Chuan (Shandong Hi-Speed Group); Sun, Renjuan (Shandong University); Hu, Xinlei (Chongqing Luneng Development Group Co, Ltd.); Guan, Yanhua (Shandong University); Yang, Yingzi (Harbin Institute of Technology); Lu, Wei (Shandong University); Tian, Jun (Shandong Hi-Speed Group); Zhang, Hongzhi (Shandong University); Ge, Zhi (Shandong University); Šavija, B. (TU Delft Materials and Environment)","","2023","This paper presents a research on the chloride penetration behavior of engineered cementitious composites (ECC) under sustained flexural loads. Three load levels, i.e. 30 %, 60 % and 75 % of the ultimate flexural load were used. Chloride diffusion depth and concentration profile were measured 30, 60 and 150 days after the specimen was exposed to NaCl solution and compared with pre-loaded specimens. Influence of the sustained local bending stress and microcracks were investigated. It shows that under sustained loads, the relationship between the surface chloride content and maximum normal tensile stress can be described using an exponential equation. A binary model was developed to explain the correlation among the chloride ion diffusion coefficient, maximum normal tensile stress and exposure time. Changes of capillary pore structure and phase compositions were measured using mercury intrusion porosimeter and X-ray diffraction, respectively. Unlike mortar, the fiber bridging of ECC helps with limiting crack width and thus the diffusion process, and the measured results were used to explain the observed penetration behavior of ECC. It is believed that the current study provides theoretical foundation for the durable design of the ECC/concrete composite structure.","Chloride penetration behavior; Engineered cementitious composites; Maximum normal tensile stress; Microcracks; Sustained flexural load","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.","","2023-10-26","","","Materials and Environment","","",""
"uuid:36e24067-2b75-496a-93a2-532dc45d5115","http://resolver.tudelft.nl/uuid:36e24067-2b75-496a-93a2-532dc45d5115","Cobalt immobilization performance and mechanism analysis of low carbon belite calcium sulfoaluminate cement","Chi, Lin (University of Shanghai for Science and Technology); Li, Mengxuan (University of Shanghai for Science and Technology); Zhang, Qianrui (University of Shanghai for Science and Technology); Liang, X. (TU Delft Materials and Environment); Huang, Chendong (University of Shanghai for Science and Technology); Peng, Bin (University of Shanghai for Science and Technology); Sun, Haisheng (University of Shanghai for Science and Technology)","","2023","Cementitious materials are well acknowledged as one of the most adaptable materials for immobilizing heavy metals. Belite calcium sulfoaluminate cement (BCSA), one of the low-carbon alternative binders to cement with superior properties regarding chemical resistance and mechanical properties, is found with a desirable capability for waste immobilization. In this study, BCSA was used for Co(II) immobilization with a dosage of up to 2.5% by weight of BCSA. The results showed that Co(II) could promote the hydration of BCSA pastes, specifically accelerated the hydration of ye'elimite. More hydration products could be generated in the Co(II)-doped BCSA pastes, leading to the construction of a denser microstructure. The compressive strength of BCSA pastes would be slightly improved when BCSA was used for Co(II) immobilization, and the electrical resistivity would decrease. In terms of Co(II) immobilization, BCSA cement exhibited a desirable capacity for Co(II) immobilization. The majority of the Co(II) could be immobilized within the first 100 min of mixing BCSA with Co(II) solutions. The immobilization degrees of Co(II) in hardened BCSA pastes could approach about 99.99% after 7d. The acquired results indicated that BCSA cement is effective for Co(II) immobilization. Therefore, BCSA has a low-carbon advantage with superior strength development over time and prospective capacity of heavy metals immobilization.","Belite calcium sulfoaluminate cement; Cement hydration; Cobalt immobilization; Hazardous waste","en","journal article","","","","","","","","","","","Materials and Environment","","",""
"uuid:df59064f-0753-4886-8976-595c06e2469b","http://resolver.tudelft.nl/uuid:df59064f-0753-4886-8976-595c06e2469b","Managing connected and automated vehicles with flexible routing at “lane-allocation-free” intersections","Hao, R. (TU Delft Transport and Planning; Tongji University); Zhang, Yuxiao (Tongji University); Ma, Wanjing (Tongji University); Yu, Chunhui (Tongji University); Sun, Tuo (Tongji University); van Arem, B. (TU Delft Transport and Planning)","","2023","With the development of internet of vehicles and automated driving, individual-based trajectory control at intersections becomes possible. Trajectory planning and coordination for connected and automated vehicles (CAVs) have been studied at isolated “signal-free” intersections and in “signal-free” corridors under the fully CAV environment in the literature. Most existing studies are based on the definition of approaching and exit lanes. The route a vehicle takes to pass through an intersection is determined by its movement. That is, only the origin and destination arms are included. This study proposes a mixed-integer linear programming (MILP) model to optimize vehicle trajectories at an isolated “signal-free” intersection without lane allocation, denoted as “lane-allocation-free” (LAF) control. Each lane can be used as both approaching and exit lanes for all vehicle movements including left-turn, through, and right-turn. A vehicle can take a flexible route by way of multiple arms to pass through the intersection. In this way, the spatial–temporal resources are expected to be fully utilized. The interactions between vehicle trajectories are modeled explicitly at the microscopic level. Vehicle routes and trajectories (i.e., car-following and lane-changing behaviors) at the intersection are optimized in one unified framework for system optimality in terms of total vehicle delay. Considering varying traffic conditions, the planning horizon is adaptively adjusted in the implementation of the proposed model to make a balance between solution feasibility and computational burden. Numerical studies validate the advantages of the LAF control in terms of both vehicle delay and throughput with different demand structures and temporal safety gaps.","Connected and automated vehicle; Flexible routing; Isolated intersection; Lane-allocation-free; Signal-free","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.","","2023-11-10","","","Transport and Planning","","",""
"uuid:72aa4611-086b-4fa6-83e6-317a03ddfa10","http://resolver.tudelft.nl/uuid:72aa4611-086b-4fa6-83e6-317a03ddfa10","Effect of white mud on properties of alkali activated slag","Sun, Renjuan (Shandong University); Bu, Linglai (Shandong University); Zhang, Hongzhi (Shandong University); Guan, Yanhua (Shandong University); Ma, Chuanyi (Shandong Hi-Speed Group); Ge, Zhi (Shandong University); Šavija, B. (TU Delft Materials and Environment)","","2023","White mud is a solid waste from the papermaking industry, composed mainly of CaCO3 and residual alkali metal ions (such as Na+, Mg2+). In the current study, the feasibility of using white mud as partial replacement of slag in alkali activated materials is explored. The fluidity, setting time, autogenous shrinkage, mechanical properties, hydration products and microstructure of alkali activated slag containing different amount of white mud are studied. The results show that adding white mud reduces the fluidity of freshly mixed paste, setting time and autogenous shrinkage. The ions released from the white mud participate in the polymerization reaction, accelerate the hydration reaction in the early stage, and promotes the precipitation of Mg-Al and the formation of hydrotalcite. However, excessive quantities of white mud (above 15% of the binder) leads to the reduction of compressive strength. As the content of white mud is enhanced, the Ca/(Si + Al) ratio of the gel increases and the degree of polymerization is reduced. It has been shown that white mud has potential reactivity and can partially replace slag to prepare new alkali activated materials.","Alkali activated slag; Hydration products; Microstructure; White mud","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.","","2023-11-30","","","Materials and Environment","","",""
"uuid:5f56732e-4580-4381-be46-42b7f31d8ab0","http://resolver.tudelft.nl/uuid:5f56732e-4580-4381-be46-42b7f31d8ab0","Ten simple rules for starting FAIR discussions in your community","Belliard, F. (TU Delft Scholarly Communications and Publishing); Maineri, Angelica Maria (Erasmus Universiteit Rotterdam); Plomp, E. (TU Delft Management Support); Padilla, Andrés Felipe Ramos (Rijksinstituut voor Volksgezondheid en Milieu (RIVM)); Sun, Junzi (TU Delft Control & Simulation); Jeddi, Maryam Zare (Rijksinstituut voor Volksgezondheid en Milieu (RIVM))","","2023","This work presents 10 rules that provide guidance and recommendations on how to start up discussions around the implementation of the FAIR (Findable, Accessible, Interoperable, Reusable) principles and creation of standardised ways of working. These recommendations will be particularly relevant if you are unsure where to start, who to involve, what the benefits and barriers of standardisation are, and if little work has been done in your discipline to standardise research workflows. When applied, these rules will support a more effective way of engaging the community with discussions on standardisation and practical implementation of the FAIR principles.","","en","journal article","","","","","","Publisher Copyright: © 2023 Belliard et al.","","","","","Scholarly Communications and Publishing","","",""
"uuid:1e960def-f997-488e-886f-4f4bc2d29ab3","http://resolver.tudelft.nl/uuid:1e960def-f997-488e-886f-4f4bc2d29ab3","An Empirical Performance Comparison between Matrix Multiplication Join and Hash Join on GPUs","Sun, W. (TU Delft Web Information Systems); Katsifodimos, A (TU Delft Web Information Systems); Hai, R. (TU Delft Web Information Systems)","","2023","Recent advances in Graphic Processing Units (GPUs) have facilitated a significant performance boost for database operators, in particular, joins. It has been intensively studied how conventional join implementations, such as hash joins, benefit from the massive parallelism of GPUs. With the proliferation of machine learning, more databases have started to provide native support for the basic building blocks of ML algorithms, i.e., linear algebra operators such as matrix multiplication (MM). Despite the recent increasing interest in processing relational joins using matrix multiplication (MM-join), two crucial questions still remain open: i) how efficient are current MM-join implementations compared to the GPU-based join algorithms; ii) how should practitioners choose among MM-join and conventional GPU-based joins given different data characteristics.In this paper, we compare the execution time, and memory I/O of MM-join against multiple GPU hash joins. An empirical analysis of our experimental results reveals that the state-of-the-art hash join implementation shows substantial scalability for various data characteristics. In contrast, MM-join outperforms the SOTA hash join in low join selectivity and low table cardinality but shows unsatisfactory scalability due to synchronous data movement and computation.","GPU; Hash Join; Matrix Multiplication Join","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.","","2023-12-14","","","Web Information Systems","","",""
"uuid:c584f05e-539c-4769-9b0a-8bc640296505","http://resolver.tudelft.nl/uuid:c584f05e-539c-4769-9b0a-8bc640296505","Slight Multielement Doping-Induced Structural Order-Disorder Transition for High-Performance Layered Na-Ion Oxide Cathodes","Guo, Hao (China Institute of Atomic Energy); Zhao, C. (TU Delft RST/Storage of Electrochemical Energy); Gao, Jianxiang (China Institute of Atomic Energy); Yang, Wenyun (Peking University); Hu, Xufeng (China Institute of Atomic Energy); Ma, Xiaobai (China Institute of Atomic Energy); Jiao, Xuesheng (China Institute of Atomic Energy); Yang, Jinbo (Peking University); Sun, Kai (China Institute of Atomic Energy); Chen, Dongfeng (China Institute of Atomic Energy)","","2023","To realize concurrently the high-energy density and excellent cycling stability, maximum utilization of redox couple, minimization of detrimental phase transition, and structural degradation of O3-type layered oxide cathodes are critical for developing Na-ion batteries. Ni2+/Ni4+ redox couple showing multielectron reaction and higher redox potential is favorable to increase the energy density. However, the Jahn-Teller distortion of Ni3+ generated upon (dis)charging results in a strong anisotropy in the local crystal structure that causes irreversible interlayer bending and chemo-mechanical cracks of the cathode particles, compromising the electrochemical properties eventually. In this work, we show a slight multielement doping strategy that enlarges the amount of active redox components while minimizing the inactive contents. The results show that the uniform distribution of multiple components can help increase the disorder degree of atom arrangement and alleviate the structural changes and detrimental anisotropy cracks. As a proof of concept, a multielement-doped O3-type Na0.9Ni0.25Cu0.05Mg0.05Zn0.05Fe0.05Al0.05Mn0.40Ti0.05Sn0.05O2 oxide is rationally prepared that presents better chemo-mechanical stability and delayed O3-P3 phase transition behavior. Compared to the high Ni-content Na0.9Ni0.35Fe0.2Mn0.45O2 cathode, this as-prepared multielement material delivers a reversible capacity of about 120 mAh/g in the voltage range of 2-4.0 V, superior cycling stability with 90% of capacity retention after 500 cycles, and excellent rate capability (more than 70% of initial capacity at 5.0 C). This work indicates that the multielement doping method is highly suitable for the development of advanced Na-ion layered oxide cathodes.","anisotropy lattice strain; multielement doping; NaNiCuMgZnFeAlMnTiSnO; O3-type; order−disorder transition","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.","","2024-01-13","","","RST/Storage of Electrochemical Energy","","",""
"uuid:698559a3-faaf-467d-a8e1-9d010b5c6cba","http://resolver.tudelft.nl/uuid:698559a3-faaf-467d-a8e1-9d010b5c6cba","High temperature viscoplastic deformation behavior of sintered nanocopper paste used in power electronics packaging: Insights from constitutive and multi-scale modelling","Hu, D. (TU Delft Electronic Components, Technology and Materials); Qian, Cheng (Fudan University); Liu, X. (TU Delft Electronic Components, Technology and Materials); Du, L. (TU Delft Electronic Components, Technology and Materials); Sun, Zhongchao (Aalborg University); Fan, X. (Lamar University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials; Fudan University); Fan, J. (TU Delft Electronic Components, Technology and Materials; Fudan University)","","2023","As a promising technology for high-power and high-temperature power electronics packaging, nanocopper (nanoCu) paste sintering has recently received increasing attention as a die-attachment. The high-temperature deformation of sintered nanoCu paste and its underlying mechanisms challenge the reliability of high-power electronics packaging. In this study, the tensile deformation behaviors of sintered nanoCu paste were firstly characterized by high-temperature tensile tests performed at various temperatures and strain rates ranging from 180 °C to 360 °C, 1 × 10−4 s−1 to 1 × 10−3 s−1 respectively. It was found that the elastic modulus and tensile strength decreased at the higher tensile temperature while the ductility increased accordingly. The highest elastic modulus and tensile strength results were 12.15 GPa and 46.97 MPa, respectively. Second, failure analysis was conducted based on the fracture surface after tensile testing. Recrystallization was revealed as the main factor for ductility improvement. Subsequently, an Anand model was fitted by stress-strain curves to describe the tensile constitutive behavior of the sintered nanoCu paste. Multi-scale modelling techniques also investigated the impact of tensile temperature and strain rate on the tensile response. Molecular dynamics simulation was implemented using a hemispherical Cu nanoparticle model to reveal the properties from an atomistic perspective. In addition, a two-dimensional equivalent model was further established by using a stochastically distributed void morphology. The multi-scale modelling techniques successfully describe the evolution of tensile response to the different tensile temperatures and strain rates. Besides, the equivalent model with random void morphology was demonstrated as the finite element simulation results were highly consistent with the high-temperature tensile experiments.","Constitutive modelling; Copper nanoparticles sintering; High-temperature tensile test; Molecular dynamics simulation stochastically equivalent finite element; Random void morphology","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:288d1928-4fba-4db7-b292-c5feacdc08a9","http://resolver.tudelft.nl/uuid:288d1928-4fba-4db7-b292-c5feacdc08a9","Advanced controls on energy reliability, flexibility and occupant-centric control for smart and energy-efficient buildings","Liu, Zhengxuan (TU Delft Design & Construction Management); Zhang, Xiang (University of Pennsylvania); Sun, Ying (Qingdao University of Technology); Zhou, Yuekuan (The Hong Kong University of Science and Technology)","","2023","Advanced controls have attracted increasing interests due to the high requirement on smart and energy-efficient (SEE) buildings and decarbonization in the building industry with optimal tradeoff strategies between energy consumption and thermal comfort of built environment. However, a state-of-the-art review is lacking on advanced controls for SEE buildings, especially considering advanced building energy systems, machine learning based advanced controls, and advanced occupant-centric controls (OCC). This study presents a comprehensive review on the latest advancement of advanced controls for SEE buildings, which covers recent research on data collection through smart metering and sensors, big data and building automation, energy digitization, and building energy simulation. Machine learning based advanced controls are comprehensively reviewed, including supervised, unsupervised and reinforcement learning, together with their roles and underlying mechanisms. In addition, advanced controls for energy security, reliability, robustness, flexibility, and resilience are further reviewed for energy-efficient and low-carbon buildings, with respect to fault detection and diagnosis, fire alarming and building energy safety, and climate change adaptation. Moreover, this study explores the advanced OCC systems and their applications in SEE buildings. Last but not the least, this study emphasizes the challenges and future prospects of the trade-off between complexity and predictive/control performance, AI-based controllers and climate change adaptation, OCC in thermal comfort and energy saving for the SEE buildings. This study offers valuable insights into the latest research progress concerning the underlying mechanisms, algorithms and applications of advanced controls for SEE buildings, paving the path for sustainable and low-carbon transition in building sectors.","Energy-efficient building; Intelligent control; Machine learning; Occupant-centric control; Smart building","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.","","2024-02-09","","","Design & Construction Management","","",""
"uuid:43118895-c9f7-4f0f-a70b-52641e79c843","http://resolver.tudelft.nl/uuid:43118895-c9f7-4f0f-a70b-52641e79c843","First-principles investigations of arsenate doping into the ettringite lattice","Zhao, Yingliang (The Hong Kong Polytechnic University; Northeastern University); Sun, Yong (Northeastern University); Guo, Z. (TU Delft Rivers, Ports, Waterways and Dredging Engineering; Northeastern University); Qiu, Jingping (Northeastern University); Sun, Xiaogang (Northeastern University)","","2023","Hazardous wastes are commonly immobilized using cementitious materials. Ettringite (Ca6Al2(OH)12(SO4)3∙26H2O) is one of the main components of hydrated cement and is known to stabilize anionic species. Thus, it is a promising material for the stabilization of arsenate (As(V)) in cementitious waste streams. However, the effects of As(V) incorporation into the ettringite structure on the structural properties of As and ettringite remain unclear. Herein, As(V) doping into the structure of ettringite was investigated based on the first-principles calculations using density functional theory (DFT), and the results suggested that the mechanism involving the substitution of AsO4 3− by SO4 2− was energetically favorable and that As doping increased the total bond order of ettringite, leading to a more stable structure. The elastic properties and anisotropy of ettringite and As-doped ettringite were also investigated using DFT calculations. The results showed that the mechanical properties of the As-doped ettringite structure were stable according to Born's criterion. Moreover, As doping increased the elastic constants and elastic modulus of ettringite but reduced its elastic anisotropy. These results provide valuable insights into the long-term stabilization of As species and their migration in cementitious wastes.","Arsenate; Elastic properties; Ettringite; First-principles calculations; Isomorphic substitution","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.","","2024-01-26","","","Rivers, Ports, Waterways and Dredging Engineering","","",""
"uuid:ac1370fe-772b-4424-bd7d-3c645887b0f9","http://resolver.tudelft.nl/uuid:ac1370fe-772b-4424-bd7d-3c645887b0f9","Increasing arsenic immobilization capacity of a binder prepared by arsenic-containing biohydrometallurgy waste: Effects of ferric/ferrous salts addition","Zhao, Yingliang (The Hong Kong Polytechnic University; Northeastern University); Sun, Yong (Northeastern University); Guo, Z. (TU Delft Rivers, Ports, Waterways and Dredging Engineering; Northeastern University); Sun, Xiaogang (Northeastern University); Qiu, Jingping (Northeastern University)","","2023","The aim of this study was to improve the immobilization capacity of a binder prepared from As-containing biohydrometallurgy waste (BAW) on arsenic (As) by modifying it with ferric/ferrous salts. The study investigated the chemical fractions of As and its leaching characteristics. Results indicated that the addition of ferric/ferrous salts significantly reduced the mid acido-soluble fraction of As, resulting in decreased As leaching. Among the four ferric/ferrous salts studied, ferrous sulfate (FeS2) performed the best, with only 0.5 wt% of FeS2 achieving satisfactory results. The influence of ferric/ferrous salts on the strength development and reaction products were also investigated. Although the incorporation of ferric/ferrous salts reduced As leaching, it also decreased the early age compressive strength of BAW. Ferric salts had a more significant impact on the strength evolution. In addition, the mechanism of Fe species on As stability using density function theory calculation was explored. Results suggested that As species could be adsorbed on the surface of Fe species through strong covalent bonds. Overall, the study demonstrated that modifying BAW using ferric/ferrous salts could effectively reduce As leaching. However, the decrease in strength especially at the early ages must be taken into consideration when using this method.","As immobilization; Biohydrometallurgy waste; Chemical additives; Density function theory","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.","","2023-11-26","","","Rivers, Ports, Waterways and Dredging Engineering","","",""
"uuid:1bf43af1-cdc8-4d26-8449-1aaf77db8a4f","http://resolver.tudelft.nl/uuid:1bf43af1-cdc8-4d26-8449-1aaf77db8a4f","Amalur: Data Integration Meets Machine Learning","Hai, R. (TU Delft Web Information Systems); Koutras, C. (TU Delft Web Information Systems); Ionescu, A. (TU Delft Web Information Systems); Li, Z. (TU Delft Web Information Systems); Sun, W. (TU Delft Web Information Systems); van Schijndel, Jessie (Student TU Delft); Kang, Yan (WeBank); Katsifodimos, A (TU Delft Web Information Systems)","","2023","Machine learning (ML) training data is often scattered across disparate collections of datasets, called data silos. This fragmentation poses a major challenge for data-intensive ML applications: integrating and transforming data residing in different sources demand a lot of manual work and computational resources. With data privacy and security constraints, data often cannot leave the premises of data silos, hence model training should proceed in a decentralized manner. In this work, we present a vision of how to bridge the traditional data integration (DI) techniques with the requirements of modern machine learning. We explore the possibilities of utilizing metadata obtained from data integration processes for improving the effectiveness and efficiency of ML models. Towards this direction, we analyze two common use cases over data silos, feature augmentation and federated learning. Bringing data integration and machine learning together, we highlight new research opportunities from the aspects of systems, representations, factorized learning and federated learning.","","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.","","2024-01-26","","","Web Information Systems","","",""
"uuid:b15178cf-2b10-4439-b4ae-03bc3c640618","http://resolver.tudelft.nl/uuid:b15178cf-2b10-4439-b4ae-03bc3c640618","Understanding fracture mode-mixity and its effects on bond performance","Blackman, Bamber (Imperial College London); Sun, Fengzhen (Tongji University); Teixeira De Freitas, S. (TU Delft Structural Integrity & Composites); De Barros, S.R. (TU Delft Structural Integrity & Composites; LINEACT CESI Engineering School); Moreira Arouche, M. (TU Delft Steel & Composite Structures); Ivankovic, Alojz (University College Dublin)","","2023","This chapter discusses the mixed-mode loading of adhesive joints. The importance of mixed-mode loading is first introduced and then test methods commonly used to measure the mixed-mode fracture resistance of adhesive joints are presented and briefly discussed. The approaches to determine the fracture resistance are briefly reviewed and then the partitioning of mixed-mode fracture energies is discussed. The limitations of the local singular field and global approaches to mixed-mode partitioning are discussed and the use and application of a semianalytical cohesive zone analysis partitioning scheme is evaluated. The limitations of the global partitioning approach are further discussed in the context of developing a scheme to design and analyze adhesive joints with dissimilar adherends (a bi-material interface). A longitudinal strain criterion is proposed in addition to the matching of flexural rigidities and the approach is validated numerically. Finally, the practical issues of crack stability, failure path selection, and the use of mixed-mode failure envelopes is considered.","Adhesive joint; Bi-material interface; Cohesive zone model; Global approach; Local approach; Mode-mixity; Partitioning","en","book chapter","Elsevier","","","","","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","","","Structural Integrity & Composites","","",""
"uuid:41c910d3-8be5-4933-abda-66ef27ba5018","http://resolver.tudelft.nl/uuid:41c910d3-8be5-4933-abda-66ef27ba5018","Online Iterative Adaptive Dynamic Programming Approach for Solving the Zero-Sum Game for Nonlinear Continuous-Time Systems with Partially Unknown Dynamics","Fu, Bin (Northwestern Polytechnical University); Sun, B. (TU Delft Control & Simulation); Guo, Hang (Northwestern Polytechnical University); Yang, Tao (Northwestern Polytechnical University); Fu, Wenxing (Northwestern Polytechnical University)","Fu, Wenxing (editor); Gu, Mancang (editor); Niu, Yifeng (editor)","2023","The current study presents an online iterative adaptive dynamic programming approach to resolve the zero-sum game (ZSG) for nonlinear continuous-time (CT) systems containing a partially unknown dynamic. The Hamilton-Jacobian-Issacs (HJI) equation is solved along the state trajectory according to the value function approximation and the policy improvement online. Relaxed dynamic programming is utilized to ensure the algorithm’s convergence. Model and costate networks were established to conduct the method. Computational simulations are performed to present the efficiency of the algorithm.","Approximation dynamic programming; Integral reinforcement learning; Online learning; Value iteration; Zero-sum game","en","conference paper","Springer","","","","","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.","","2023-09-10","","","Control & Simulation","","",""
"uuid:4cd69d72-840f-4e7b-8f4a-91f09ab6fc9b","http://resolver.tudelft.nl/uuid:4cd69d72-840f-4e7b-8f4a-91f09ab6fc9b","ricME: Long-Read Based Mobile Element Variant Detection Using Sequence Realignment and Identity Calculation","Ma, Huidong (Guangxi University; Key Laboratory of Parallel, Distributed and Intelligent Computing in Guangxi Universities and Colleges); Zhong, Cheng (Guangxi University; Key Laboratory of Parallel, Distributed and Intelligent Computing in Guangxi Universities and Colleges); Sun, Hui (Nankai University); Chen, Danyang (Guangxi University; Key Laboratory of Parallel, Distributed and Intelligent Computing in Guangxi Universities and Colleges); Lin, H.X. (TU Delft Mathematical Physics)","Guo, Xuan (editor); Mangul, Serghei (editor); Patterson, Murray (editor); Zelikovsky, Alexander (editor)","2023","The mobile element variant is a very important structural variant, accounting for a quarter of structural variants, and it is closely related to many issues such as genetic diseases and species diversity. However, few detection algorithms of mobile element variants have been developed on third-generation sequencing data. We propose an algorithm ricME that combines sequence realignment and identity calculation for detecting mobile element variants. The ricME first performs an initial detection to obtain the positions of insertions and deletions, and extracts the variant sequences; then applies sequence realignment and identity calculation to obtain the transposon classes related to the variant sequences; finally, adopts a multi-level judgment rule to achieve accurate detection of mobile element variants based on the transposon classes and identities. Compared with a representative long-read based mobile element variant detection algorithm rMETL, the ricME improves the F1-score by 11.5 and 21.7% on simulated datasets and real datasets, respectively.","identity calculation; mobile element variants; sequence realignment; third-generation sequencing data","en","conference paper","Springer","","","","","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.","","2024-04-08","","","Mathematical Physics","","",""
"uuid:8520b119-d469-4cdb-b020-d805775b2225","http://resolver.tudelft.nl/uuid:8520b119-d469-4cdb-b020-d805775b2225","Adaptive Dynamic Programming for Flight Control","van Kampen, E. (TU Delft Control & Simulation); Sun, B. (TU Delft Electronic Components, Technology and Materials)","L'Afflitto, Andrea (editor); Inalhan, Gokhan (editor); Shin, Hyo-Sang (editor)","2023","Adaptive dynamic programming (ADP) is a sub-field of approximate dynamic programming that deals with the adaptive control of continuous nonlinear dynamic systems. Its origins stem from dynamic programming in optimal control, but it is extended into a form where approximations are used to reduce the curse of dimensionality and reduce the need for model knowledge. ADP is also considered to be one of the main reinforcement learning (RL) approaches since it uses information obtained from interaction with the environment to improve its policy. RL in general and ADP in particular are well suited for application to autonomous aerospace systems, since they allow adaptive control in case of uncertainties or faults in the system, even if the fault is of a type that is not anticipated during the control design. This chapter first gives a brief historical overview of ADP applications to flight control tasks. After that, four recent advances of ADP for flight control are presented.","","en","book chapter","Springer","","","","","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.","","2024-06-03","","","Control & Simulation","","",""
"uuid:bc6ad0d8-409d-48f8-a2b9-15eab543ff8e","http://resolver.tudelft.nl/uuid:bc6ad0d8-409d-48f8-a2b9-15eab543ff8e","Effect of Activator Solutions on the Thixotropic Behavior of Alkali-Activated Slag Concrete","Sun, Yubo (Universiteit Gent); Ghorbani, Saeid (Universiteit Gent); Ye, G. (TU Delft Materials and Environment; Universiteit Gent); De Schutter, Geert (Universiteit Gent)","","2023","Alkali-activated material (AAM) is developed as a green alternative binder to replace Portland cement (PC) in the construction field. However, the large-scale application with AAM concrete is limited so far, with the insufficient knowledge of rheological behavior being a major obstruct. Thixotropy of concrete is of great interest, which can be helpful to predict various early-age performances. The current study dedicates to evaluating the thixotropy of alkali-activated slag (AAS) concrete mixtures with different silicate and water content in activator solutions. In specific, the silicate modulus (Ms) and water to binder (w/b) ratio have been varied. The thixotropic index calculated by the initial and equilibrium shear stress from the stress growth test, as well as the breakdown area obtained by applying different shear speeds were used to evaluate the thixotropy of AAM concrete. Results indicate a good correlation between different approaches. It was found that an increase in Ms led to more pronounced thixotropic behaviors in AAS concrete due to the rapid nucleation and accumulation of early hydration products, resulting in significant increases in peak torque values and slight reductions of torque at equilibrium. Besides, the concrete thixotropy gradually declined by applying a higher w/b ratio.","Activators; Alkali-activated slag; Concrete; Rheology; Thixotropy","en","book chapter","Springer","","","","","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.","","2023-12-09","","","Materials and Environment","","",""
"uuid:057e8af3-2867-4691-a6a8-cc77b1697306","http://resolver.tudelft.nl/uuid:057e8af3-2867-4691-a6a8-cc77b1697306","Chinese Notions of Public Space: Transculturation in Urban Design and Architecture after the ‘Reform and Opening-up’ in 1978","Sun, Wenwen (TU Delft Theory, Territories & Transitions)","Cavallo, R. (promotor); Harteveld, Maurice (promotor); Delft University of Technology (degree granting institution)","2022","This doctoral research investigates the understanding and implementation of public space in the reformed Chinese context, particularly from the perspectives of urban design and architecture, by referring to the complex process and result of transculturation (transculturación). It delineates how public space as a Greco-Roman originated concept traversed the urban and architectural cultures of post-reform China, merging and negotiating with the local conditions, and evolved into a new phenomenon in Chinese urban design and architecture. This research first critically reviews contemporary narratives from Chinese philosophy and sociology, then materials written in post-reform China on the topic of public space. It then analyses various cases in their design and spatial conditions, ranging from ‘shared spaces’ in the areas characterised by urban dwelling and communities to ‘open spaces’ in the central city where strangers mingle and globalisation manifests. By analysing public space as a cultural phenomenon, carrying specific meaning, through specific concepts and designs, this research develops an interpretative framework within which the meanings and transculturation of public space in Chinese urban design and architecture can be understood and elucidates potential for future urban design and architectural practices. Theoretically, it moves beyond the conventional research on public space that is primarily based on Western thoughts, an Indo-European notion, and a Greco-Roman tradition. Practically, it paves the way for future development of the design of public space, highlighting the cultural, social, and spatial dynamics in Chinese cities vis-à-vis the related political, economic, and governmental conditions within the context of ongoing globalisation.","public space; the public realm; post-reform China; transculturation; urban design","en","doctoral thesis","TU Delft OPEN Publishing","978-94-6366-599-5","","","","A+BE | Architecture and the Built Environment No 19 (2022)","","","","","Theory, Territories & Transitions","","",""
"uuid:e6e7ddf2-96cf-4d43-aa94-243c52acc4e1","http://resolver.tudelft.nl/uuid:e6e7ddf2-96cf-4d43-aa94-243c52acc4e1","Quasi-vertical Gallium Nitride Diodes for Microwave Power Applications","Sun, Y. (TU Delft Electronic Components, Technology and Materials)","Zhang, Kouchi (promotor); van Driel, W.D. (promotor); Delft University of Technology (degree granting institution)","2022","The deployment of fifth-generation (5G) networks requires more closely spaced wireless infrastructures with a high output power to deal with high-frequency signal attenuation issues. Microwave power limiters have been widely used in the RF front-end in various wireless communication systems. A diode limiter circuit prevents the damage of sensitive receiver components by allowing RF signals below a certain threshold to pass through, while larger signals exceeding the threshold are attenuated. Many studies have been carried out on Si-based diode limiters in recent years; however, they have shown scant room for further improvement as silicon reaches its theoretical limitations. From this perspective, there is a need for new semiconductor materials to satisfy the requirements of devices. Wide-bandgap materials (e.g., gallium nitride) have recently attracted a great deal of interest due to their superior material properties such as wide band-gap, high electron saturation velocity, and high critical electric field.
Although lateral-structure GaN devices are staying ahead of the pace of industrialization, they still face several constraints and do not reach the GaN material limit due to requiring a high epitaxial layer quality and precise processing. A vertical structure is a convenient solution in Si- or SiC-based devices, which are also attractive alternatives to GaN devices. Quasi-vertical GaN devices have the freedom to select substrates (such as silicon, sapphire, and SiC) by using hetero-epitaxial growth technology. A planar structure design is easy to integrate with other RF components. This dissertation aimed to develop a quasi-vertical GaN diode for high-power RF and microwave applications which could operate in a wide frequency band and at high input power levels, with easy integration and low cost. The scope of this dissertation involved three aspects: design and fabrication of a quasi-vertical GaN device with mesa etching optimization; suppression of reverse leakage with an enhanced breakdown voltage; demonstration of microwave power applications (limiters and detectors) based on developed GaN diodes.
First, a literature summary of the state-of-the-art vertical GaN SBDs is presented in Chapter 2. A trade-off between the 𝑅𝑜𝑛,𝑠𝑝 and BV of a diode is analyzed to characterize the performance of diodes. We discuss the benchmark of 𝑅𝑜𝑛,𝑠𝑝 and BV for vertical GaN SBDs with different substrates (Si, sapphire, and GaN) and various edge terminal techniques. The equivalent circuit model of a diode for studying the high-frequency properties is introduced.Second, the optimization of mesa etching for a quasi-vertical GaN SBD by inductively coupled plasma (ICP) etching is comprehensively investigated in this chapter. In particular, the microtrench at the bottom corner of the mesa is eliminated by optimizing etch recipes. For the photoresist (PR) masked GaN samples, high source power is the cause of deteriorated mesa sidewall morphology. Although high-temperature (>140 ℃) hard baking prior to etching can produce a smooth sidewall, the drawbacks are significant and include oblique sidewall profile formation and hard striping. For the 𝑆𝑖𝑂2-masked GaN samples, the micro-trench problem at the bottom corner of the mesa can be reduced or eliminated by reducing the source power or by adding 𝐵𝐶𝑙3 into the 𝐶𝑙2 plasma. After ICP etching, the use of a TMAH wet treatment for samples can obtain a near-90° steep mesa sidewall that is microtrench-free and has a smooth surface. The proposed etching technique can be extended to other GaN nanostructures, such as hexagonal pyramids and nanowire arrays, which is promising for sensors, vertical transistors, optoelectronics, and photovoltaics.Third, a quasi-vertical GaN SBD is developed from the perspective of epilayer design, device layout, device modeling, fabrication, and leakage suppression. The design flow and fabrication process of quasi-vertical GaN diodes for microwave power applications are presented. Three solutions are developed to suppress the leakage current, namely, mesa optimization, argon ion terminations, and post-mesa nitridation. The experiment results show that our diode has the lowest leakage current density at 80% of the BV among the reported vertical GaN SBDs for a BV between 120 and 250 V. Combining mesa optimization and post-mesa nitridation technology effectively enhances the breakdown voltage and achieves excellent conduction characteristics.Fourth, a high-performance quasi-vertical GaN Schottky diode on a sapphire substrate and its application for high-power microwave circuits are investigated. We experimentally demonstrate the use of a vertical GaN SBD for L-band microwave power limiters for the first time ever. The GaN SBD limiter can handle at least 40 dBm of CW input power at 2 GHz without failure, which is comparable to a commercial Si-based diode limiter. Then, we experimentally demonstrate a quasi-vertical GaN SBD with post-mesa nitridation for high-power and broadband microwave detection. The fabricated quasi-vertical GaN diode reaches a high forward current density of 9.19 𝑘𝐴/𝑐𝑚2 at 3 V, and BV of 106 V. An extremely high output current of 400 mA is obtained when the detected power reaches 38.4 dBm at 3 GHz in pulsed-wave mode.Finally, all of the research content mentioned in this thesis is summarized, and the problems needing to be further investigated with lucubrate direction are indicated.","Gallium Nitride (GaN); Schottky Barrier Diodes (SBD); microwave power limiter; microwave power detector; quasi-vetical","en","doctoral thesis","","978-94-6421-787-2","","","","","","2023-06-27","","","Electronic Components, Technology and Materials","","",""
"uuid:34dee93a-fcb3-4e37-81f4-ab0ec652209c","http://resolver.tudelft.nl/uuid:34dee93a-fcb3-4e37-81f4-ab0ec652209c","Parameter identification of layered systems using moving loads","Sun, Z. (TU Delft Pavement Engineering)","Scarpas, Athanasios (promotor); Erkens, S. (promotor); van Dalen, K.N. (promotor); Delft University of Technology (degree granting institution)","2022","An elegant approach to evaluate the quality of engineering structures is the Non- Destructive Testing (NDT). In the field of pavement engineering, a promising NDT method for pavement structural evaluation at network level is the Traffic Speed Deflectometer (TSD) test, which can continuously measure the surface response of pavements caused by moving loads at normal driving speeds. However, the wide application of the TSD test has been hindered by the lack of a commonly accepted parameter identification technique to process TSD measurements. To tackle this problem, this dissertation aims to formulate a mechanically correct, numerically accurate, and computationally efficient parameter identification technique specifically for the TSD test of pavements. The developed parameter identification technique is the combination of a theoretical model of the TSD test and a minimisation algorithm. The unknown parameters can be identified by minimising the differences between modelled and measured response of pavements...","","en","doctoral thesis","","978-94-6366-553-7","","","","","","2023-06-19","","","Pavement Engineering","","",""
"uuid:be761a38-a87a-4e87-9343-7f838ccf6c89","http://resolver.tudelft.nl/uuid:be761a38-a87a-4e87-9343-7f838ccf6c89","Modelling and Analysis of Atrial Epicardial Electrograms: An approach based on graph signal processing and confirmatory factor analysis","Sun, M. (TU Delft Signal Processing Systems)","van der Veen, A.J. (promotor); Hendriks, R.C. (promotor); de Groot, N.M.S. (promotor); Delft University of Technology (degree granting institution)","2022","Atrial fibrillation (AF) is a frequently encountered cardiac arrhythmia characterized by rapid and irregular atrial activity, which increases the risk of strokes, heart failure and other heart-related complications. The mechanisms of AF are complicated. Although various mechanisms were proposed in previous research, the precise mechanisms of AF are not clear yet and the optimal therapy for AF patients are still under debated. A higher success rate of AF treatments requires a deeper understanding of the problem of AF and potentially a better screening of the patients.
In order to study AF, instead of using human body surface ECGs, we use the epicardial electrograms (EGMs) obtained directly from the epicardial sites of the human atria during open heart surgery. This data is measured using a high-resolution mapping array and exhibits irregular properties during AF. Although different studies have analyzed electrograms in time and frequency domain, there remain many open questions that require alternative and novel tools to investigate AF.
Experience in signal processing suggests that incorporating the spatial dimension into the time-frequency analysis on the multi-electrode electrograms may provide improved insights on the atrial activity. However, the electrophysiologcial models for describing spatial propagation are relatively complex and non-linear such that conventional signal processing methods are less suitable for a joint space, time, and frequency domain analysis. It is also difficult to use very detailed electrophysiologcial models to extract tissue parameters related to AF from the high-dimensional data.
In this dissertation, we wish to propose a radically different approach to study and analyze the EGMs from a higher abstraction level and from different perspectives to get more understanding of the characteristics of AF. We also aim to develop a simplified electrophysiological model that can capture the spatial structure of the data and propose an efficient method to estimate the tissue parameters, which are helpful to analyze the electropathology of the tissue, e.g., cell activation time or conductivity.
In the first part of this study, we put forward a graph-time spectral analysis framework to analyze EGMs during normal heart rhythm and AF with a higher-level model. To capture the frequency content along both time domain and graph domain, we propose the joint graph and short-time Fourier transform, which allows us to evaluate the temporal and spatial variation of EGMs and capture the interaction between space and time. The spectral analysis of the EGMs helps us to recognize atrial fibrillation impact on the atrial activity and identify the differences between the atrial activity and the ventricular activity. We find that the difference in graph smoothness between the atrial and ventricular activities enables us to better extract the atrial activity from the noisy measurements.
The second part of this study is to find a simplified but accurate enough electrophysiological model for the high dimensional EGMs and to make more efficient use of the data to detect the arrythmogenic substrate that causes abnormalities in atrial tissue. In this dissertation, we develop the cross power spectral density matrix (CPSDM) model of the multi-electrode EGMs and make use of an effective method called confirmatory factor analysis (CFA) to jointly estimate the model parameters. The conductivity, the activation time, and the anisotropy ratio are useful parameters to determine abnormalities in cardiac tissue and are therefore the target parameters to be estimated. With the reasonable assumptions that the conductivity parameters and the anisotropy parameters are constant across different frequencies and heart beats, and the activation time of cells are constant across different frequencies, we propose simultaneous CFA (SCFA) to jointly estimate these parameters using multiple frequencies and multiple heart beats. The identifiability conditions which need to be satisfied in the CFA problem are used to find the relationship between the desired resolution and the required amount of data. Evaluations on the simulated data and the clinical data demonstrate that the proposed method can localize the conduction blocks in the tissue and reconstruct the clinical EGMs well using the estimated parameters.","Atrial fibrillation; epicardial electrograms; spectral analysis; graphtime signal processing; electrophysiological model; cross-power spectral density matrix model; conductivity estimation; activation time estimation; anisotropy ratio estimation; confirmatory factor analysis","en","doctoral thesis","","978-94-6366-545-2","","","","","","","","","Signal Processing Systems","","",""
"uuid:aa6b67ad-6801-43eb-9772-2e96a75211f1","http://resolver.tudelft.nl/uuid:aa6b67ad-6801-43eb-9772-2e96a75211f1","Calculation of dam risk probability of cascade reservoirs considering risk transmission and superposition","Wang, Te (Zhengzhou University); Li, Zongkun (Zhengzhou University); Ge, W. (TU Delft Safety and Security Science; Zhengzhou University); Zhang, Yadong (Zhengzhou University); Jiao, Yutie (Zhengzhou University); Sun, Heqiang (Zhengzhou University); Zhang, Hua (Zhengzhou University)","","2022","Because of the risk transmission and superposition among dams in cascade reservoirs, the analysis and probability calculation of dam risk become more complex compared with a single reservoir. By analyzing the main risk sources and actionmechanisms, the disaster-causing factors, disaster-transmitting body and disaster-bearing body in the cascade reservoirs system were determined. By defining the influence coefficient (IC) to express the transmission and superposition degree of dam risk among cascade reservoirs, dam risk was divided into two parts: own risk (OR) and additional risk (AR). On this basis, the relevant concepts and equations for the calculation of the dam risk probability of cascade reservoirs were proposed. The numerical simulation was carried out to quantify the IC, and a Bayesian network analysis model was constructed to calculate the OR. Finally, taking five cascade reservoir dams in the Dadu River basin as examples, the value of their ORs, ARs and risk probabilities were calculated, and thereafter the weakest cascade, controlling cascade and general cascade in the system were divided. The proposed methodology realizes an effective connection with the dam risk calculation method of a single reservoir, which can provide a reference for the risk assessment and management of cascade reservoirs in the basin.","Cascade reservoirs; Dam break; Probability; Risk superposition; Risk transmission","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.","","2023-07-01","","","Safety and Security Science","","",""
"uuid:724acbc5-64b6-41d9-8142-dea2b137b8af","http://resolver.tudelft.nl/uuid:724acbc5-64b6-41d9-8142-dea2b137b8af","Aerosol Absorption from Global Satellite Measurements in the Ultra-Violet: From Qualitative Aerosol Index to Quantitative Aerosol Absorptive Properties","Sun, J. (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI))","Levelt, Pieternel Felicitas (promotor); Veefkind, j. Pepijn (copromotor); Delft University of Technology (degree granting institution)","2022","Atmospheric aerosols are solid or liquid particles suspended in the air. The majority of them are produced by natural processes, including sea salt from oceans, mineral dust from (semi-)arid regions, carbon containing particles from wildfires, and sulfates and ash from volcanic activities. Anthropogenic aerosols are produced by industrial activities, power generation, transportation, agriculture, and human-induced biomass burning events. Depending on the meteorological conditions, aerosol particles can stay in the atmosphere for several hours to several months and can be transported over long distances, causing adverse effects on human health, visibility and climate.
This thesis focuses on the aerosol optical properties, particularly the light absorption of the aerosol particles that has significant effects on the Earth’s climate system.
This thesis starts with a general introduction of atmospheric aerosols, including its sources, categories, physical properties and measurement techniques (Chapter 1). Next, the Ultra-Violet Aerosol Index (UVAI) is introduced, which is calculated from satellite measurements of the radiance at two wavelengths in the UV. UVAI contains information of aerosol absorption, and it has a very long and
almost continuous data record starting in 1978. Direct use of UVAI is challenging because it is not a geophysical quantity, but a numerical index. The objective of this thesis is to derive quantitative properties on aerosol absorption from the UVAI (e.g. single scattering albedo, absorption aerosol optical depth) that can be directly used in aerosol radiative transfer assessments. Two types of methods have been developed, i.e. physically-based methods and statistically-based methods. The first compares the observed UVAI to the one simulated by radiative transfer models. The second uses Machine Learning algorithms trained by existing data sets.
The physically-based methods have been applied to quantify aerosol absorption of several large scale wildfires (Chapter 2 and 3). An important challenge of these method is that assumptions have to be made on the aerosol micro-physical properties, leading to significant uncertainties in the results, whereas theMachine Learning-based methods can avoid this kind of assumptions. Chapter 3 investigates the feasibility to quantify aerosol absorption from UVAI using a Machine Learning algorithm. Despite the higher computational efficiency and better results, the application of such data-driven methods is still restricted by the limited data on the aerosol vertical distribution. Therefore, in Chapter
4, a database of aerosol height is created from a chemistry transport model. This database is applied in Chapter 5, where a Deep Neural Network method is used to derive the quantitative aerosol absorptive properties from the OMI/Aura UVAI for the period from 2006 to 2019. In comparison to ground-based observations, the results of the Deep Neural Network agree better than satellite retrievals and also better than chemistry transport model simulations.
This thesis demonstrates the feasibility of deriving quantitative aerosol absorptive properties from the satellite retrieved UVAI.We use traditional radiative transfer simulations meanwhile investigating the new possibilities of data-driven methods in aerosol remote sensing. Although the retrieval results are encouraging, there remain limitations and challenges which need to be addressed. These are discussed in Chapter 6 with corresponding suggestions and prospects. Despite the challenges, it is expected that a synthetic database of global aerosol absorption can be derived fromUVAI observations provided by multiple satellite products. Such a data set will make great contributions to quantify the effect of absorbing aerosols on the climate system.","Atmospheric Remote Sensing; aerosol climatology; Absorbing aerosol; Aerosol; Aerosol optical property","en","doctoral thesis","","9789463843065","","","","","","","","","Atmospheric Remote Sensing","","",""
"uuid:29dc55b9-f992-4246-a340-51e40d823451","http://resolver.tudelft.nl/uuid:29dc55b9-f992-4246-a340-51e40d823451","Robustness of controllability and recoverability of complex networks","Sun, P. (TU Delft Network Architectures and Services)","Van Mieghem, P.F.A. (promotor); Kooij, Robert (promotor); Delft University of Technology (degree granting institution)","2022","Network robustness describes a network's ability to provide and maintain an acceptable level of service in the face of failures and challenges to normal operation. Unfortunately, failures of networks, such as power outages in power systems, congestions in transportation networks, failures of routers on the Internet, happen frequently in our daily life and introduce a tremendous cascading effect on our society. We naturally expect that these networks have high robustness to maintain their performance in face of failures or attacks. As the first step, it is vital to investigate and analyze the robustness of networks so as to propose effective methods to improve network robustness.
The first part of the thesis mainly focuses on the robustness of network controllability in face of topological perturbations. In Chapter 2, we propose closed-form analytic approximations for the minimum number of driver nodes which denotes the controllability of the network. Inspired by the concept of critical links, we deduce and validate our approximations on both real-world and synthetic networks. We show that when the fraction of removed links is small, our approximations perform well. Besides, we also find that the critical link attack is the most effective among 4 considered attacks, as long as the fraction of removed links is smaller than the fraction of critical links. In Chapter 3, we focus on the controllability of swarm signalling networks with regular out-degree and bi-modal out-degree distribution. We deduce the generating functions in random failure process and then estimate the fraction of driver nodes with simulations. Results show that our estimations have high accuracy in predicting the fraction of driver nodes in case of random link failures. In order to further improve the accuracy of our proposed approximations in Chapter 4, we use a machine learning method to decrease the gap between our analytical approximations and the simulation results. We compare our approximations obtained by machine learning with existing analytical approximations and show that our approximations significantly outperform the existing closed-form analytical approximations in both synthetic and real-world networks. Apart from targeted attacks based upon the removal of critical links, we also propose analytical approximations for out-in degree-based attacks. In Chapter 5, we investigate the reachability-based robustness of controllability considering link-based random attack, targeted attack, as well as random attack under the protection of critical links. We validate our approximations using 200 real-world communication networks and some synthetic networks and find that our approximations perform well in most cases.
In the second part of the thesis, we work on the recoverability of networks. The recoverability of networks refers to the ability of a network to return to a desired performance level after suffering topological perturbations such as link failures. In Chapter 6, we propose a general topological approach and two recoverability indicators to measure the network recoverability for optical networks for two recovery scenarios. Furthermore, we employ the proposed approach to assess 20 real-world optical networks. Numerical results show that the network recoverability is coupled to the network topology, the robustness metric and the recovery strategy. We also find that assortativity, which denotes the tendency of network nodes to connect preferentially to other nodes with similar degree, has the strongest correlation with both recoverability indicators. In Chapter 7, we adopted the framework of network recoverability and investigate the recoverability of network controllability for two recovery scenarios. We employ the proposed approach to assess swarm signalling networks with regular out-degree, and networks with bi-modal out-degree distributions. Besides, we also deduced the analytical results of the recoverability indicators by generating functions, which are close to the results based on simulations. In Chapter 8, we conclude this thesis and come up with some future work.","Controllability; Recoverability; Robustness; Complex Networks","en","doctoral thesis","","978-94-6423-609-5","","","","","","","","","Network Architectures and Services","","",""
"uuid:8a1ea4b1-d144-4981-8b20-c292987d10b4","http://resolver.tudelft.nl/uuid:8a1ea4b1-d144-4981-8b20-c292987d10b4","Temporal Network Prediction and Interpretation","Zou, L. (TU Delft Multimedia Computing); Zhan, Xiu xiu (Hangzhou Normal University); Sun, Jie (Huawei Technologies); Hanjalic, A. (TU Delft Intelligent Systems); Wang, H. (TU Delft Multimedia Computing)","","2022","Temporal networks refer to networks like physical contact networks whose topology changes over time. Predicting future temporal network is crucial e.g., to forecast the epidemics. Existing prediction methods are either relatively accurate but black-box, or white-box but less accurate. The lack of interpretable and accurate prediction methods motivates us to explore what intrinsic properties/mechanisms facilitate the prediction of temporal networks. We use interpretable learning algorithms, Lasso Regression and Random Forest, to predict, based on the current activities (i.e., connected or not) of all links, the activity of each link at the next time step. From the coefficients learned from each algorithm, we construct the prediction backbone network that presents the influence of all links in determining each links future activity. Analysis of the backbone, its relation to the link activity time series and to the time aggregated network reflects which properties of temporal networks are captured by the learning algorithms. Via six real-world contact networks, we find that the next step activity of a particular link is mainly influenced by (a) its current activity and (b) links strongly correlated in the time series to that particular link and close in distance (in hops) in the aggregated network.","Epidemics; link prediction; Machine learning algorithms; Network topology; Prediction algorithms; prediction backbone network; Random forests; temporal network; Time series analysis; Training","en","journal article","","","","","","","","","","Intelligent Systems","Multimedia Computing","","",""
"uuid:9c71a11e-4f1e-4ec8-869b-15a7d3bcc50b","http://resolver.tudelft.nl/uuid:9c71a11e-4f1e-4ec8-869b-15a7d3bcc50b","Distributed Adaptive Fixed-Time Fault-Tolerant Control for Multiple 6-DOF UAVs With Full-State Constraints Guarantee","Zhang, Boyang (Air Force Engineering University China); Sun, Xiuxia (Air Force Engineering University China); Lv, Maolong (TU Delft Team Bart De Schutter; Air Force Engineering University China); Liu, Shuguang (Air Force Engineering University China); Li, Le (Northwestern Polytechnical University)","","2022","In contrast with most existing results concerning unmanned aerial vehicles (UAVs) wherein material points or only attitude/longitudinal dynamics are considered, this article proposes a distributed fixed-time fault-tolerant control methodology for networked fixed-wing UAVs whose dynamics are six-degree-of-freedom with twelf-state-variables subject to actuator faults and full-state constraints. More precisely, state transformations with the scaling function are devised to keep the involved velocity and attitude within their corresponding constraints. The fixed-time property is obtained in the sense of guaranteeing that the settling time is lower bounded by a positive constant, which is independent of initial states. The actuator faults as well as the network induced errors are handled via the bound estimation approach and well-defined smooth functions. By strict Lyapunov arguments, all closed-loop signals are proved to be semiglobally uniformly ultimately bounded, and the tracking errors of velocity and attitude converge to the residual sets around origin within a fixed time.","Actuators; Aerodynamics; Convergence; Fault tolerance; Fault tolerant systems; Fault-tolerant control (FTC); fixed-time convergence; full-state constraints; six-degree-of-freedom (DOF) fixed-wing unmanned aerial vehicles (UAVs); Uncertainty; Vehicle dynamics","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.","","2023-07-01","","","Team Bart De Schutter","","",""
"uuid:8ad9b284-759e-4e70-acd1-727e7cf49872","http://resolver.tudelft.nl/uuid:8ad9b284-759e-4e70-acd1-727e7cf49872","Direct Trajectory Optimization of Free-Floating Space Manipulator for Reducing Spacecraft Variation","Shao, X. (TU Delft Learning & Autonomous Control; Harbin Institute of Technology); Yao, Weiran (Harbin Institute of Technology); Li, Xiaolei (Harbin Institute of Technology); Sun, Guanghui (Harbin Institute of Technology); Wu, Ligang (Harbin Institute of Technology)","","2022","This letter investigates the direct trajectory optimization of the free-floating space manipulator (FFSM). The main purpose is to plan the joint space trajectories to reduce the spacecraft motion due to the joint rotation during the FFSM performing tasks. To improve the calculation efficiency, the adaptive Radau pseudospectral method (A-RPM) is applied to discretize the system dynamics and transform the formulated optimal problem into a nonlinear programming problem (NLP). By adaptively subdividing the current segment and assigning collocation points according to the solution error, high-degree interpolation polynomials are avoided. To verify the effectiveness of the proposed method, a ground micro-gravity platform of the FFSM system is designed by using the air-bearing technique, on which experiments are carried out. The results show that the variation of the base spacecraft is dramatically reduced if the joints rotate along the optimized trajectories.","Direct trajectory optimization; free-floating space manipulator; radau pseudospectral method; spacecraft variation reduction","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.","","2023-07-01","","","Learning & Autonomous Control","","",""
"uuid:1658a135-40cd-4d2f-9f24-9866ce1022ed","http://resolver.tudelft.nl/uuid:1658a135-40cd-4d2f-9f24-9866ce1022ed","Distributed Coordinated Control for Fixed-Wing UAVs with Dynamic Event-Triggered Communication","Zhang, Boyang (Air Force Engineering University China); Sun, Xiuxia (Air Force Engineering University China); Lv, Maolong (TU Delft Team Bart De Schutter); Liu, Shuguang (Air Force Engineering University China)","","2022","Compared with most existing results concerning unmanned aerial vehicles (UAVs) wherein two-degree or only attitude/longitudinal dynamics are considered, this paper proposes an event-based fault-tolerant coordinated control (FTC) for multiple fixed-wing UAVs such that the consensus tracking of velocity and attitude is achieved in the presence of actuator faults, external disturbances and modeling uncertainties. More precisely, as opposed to static event-triggered communication mechanisms, a dynamic event-triggered communication mechanism (DECM) is devised to schedule the connected communications while avoiding the unnecessary information exchanges among UAVs, which reduces the communication burden and saves on the network resources. Meanwhile, the Zeno phenomenon is excluded in terms of guaranteeing that the period between two consecutive triggering communication is lower bounded by a positive constant. Moreover, the actuator fault, external disturbance as well as model uncertainty are treated as the lumped disturbances and estimated via the disturbance observer technique. By strict Lyapunov arguments, all closed-loop signals are proved to be uniformly ultimately bounded (UUB) and the tracking errors of velocity and attitude converge to a residual set around origin. Finally, simulation results are presented to illustrate the validity and superiority of proposed event-based control scheme.","Actuators; Aerodynamics; Attitude control; Dynamic event-triggered communication mechanism; Fault tolerance; Fault tolerant systems; fault-tolerant control; fixed-wing unmanned aerial vehicles; Nonlinear dynamical systems; Vehicle dynamics","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.","","2023-07-01","","","Team Bart De Schutter","","",""
"uuid:25cdac7d-3055-48c1-9870-8e9e2fd18c6f","http://resolver.tudelft.nl/uuid:25cdac7d-3055-48c1-9870-8e9e2fd18c6f","Evaluating the strength of grade 10.9 bolts subject to multiaxial loading using the micromechanical failure index: MCEPS","Xin, Haohui (Xi’an Jiaotong University); Li, Jie (Xi’an Jiaotong University); Veljkovic, M. (TU Delft Steel & Composite Structures); Liu, Yuqing (Tongji University); Sun, Qing (Xi’an Jiaotong University)","","2022","Bolted joints in steel structures are generally subject to combined actions. The research on ultimate capacity of bolted joints under combined tension and shear actions, twin shear actions, and combined tension-twin shear actions is relatively limited. The aim of this paper is to calibrate the fracture locus of grade 10.9 bolts using the mesoscale critical equivalent plastic strain (MCEPS). We use ductile fracture simulation to numerically evaluate the ultimate resistance of bolts subject to multiaxial loading and compare the results with the current design standards. The results show that predictions for grade 10.9 bolts subject to multiaxial loading in Chinese code GB 50017 and American code AISC-360 are not on the safe side, while predictions in European code EN1993-1-8:2005 are slightly on the conservative side. We propose two modification factors to improve prediction of bolt strength subject to multiaxial loading; namely the multiaxial loading factor for shear resistance ξv and the multiaxial loading factor for tensile resistance ξt.","Analysis and design; ductile fracture; General; high-strength bolts; Materials; multiaxial loading; ultimate capacity","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.","","2022-08-26","","","Steel & Composite Structures","","",""
"uuid:b4357fc6-7d06-4394-bf2f-796958d891d4","http://resolver.tudelft.nl/uuid:b4357fc6-7d06-4394-bf2f-796958d891d4","Joint cardiac tissue conductivity and activation time estimation using confirmatory factor analysis","Sun, M. (TU Delft Signal Processing Systems); de Groot, N.M.S. (Erasmus MC); Hendriks, R.C. (TU Delft Signal Processing Systems)","","2022","Mathematical models of the electrophysiology of cardiac tissue play an important role when studying heart rhythm disorders like atrial fibrillation. Model parameters such as conductivity, activation time, and anisotropy ratio are useful parameters to determine the arrhythmogenic substrate that causes abnormalities in the atrial tissue. Existing methods often estimate the model parameters separately and assume some of the parameters to be known as a priori knowledge. In this work, we propose an efficient method to jointly estimate the parameters of interest from the cross power spectral density matrix (CPSDM) model of the electrograms. By applying confirmatory factor analysis (CFA) to the CPSDMs of multi-electrode electrograms, we can make use of the spatial information of the data and analyze the relationship between the desired resolution and the required amount of data. With the reasonable assumptions that the conductivity parameters and the anisotropy parameters are constant across different frequencies and heart beats, we estimate these parameters using multiple frequencies and multiple heart beats simultaneously to easier satisfy the identifiability conditions in the CFA problem. Results on the simulated data show that using multiple heart beats decreases the estimation errors of the conductivity and the estimated activation time parameters. The experimental results on clinical data show that using multiple heart beats for parameter estimation can reduce the reconstruction errors of the clinical electrograms, which further demonstrates the robustness of the proposed method.","Activation time estimation; Conductivity estimation; Confirmatory factor analysis; Cross power spectral density","en","journal article","","","","","","","","","","","Signal Processing Systems","","",""
"uuid:9b567959-9541-45a6-bd92-94e7b1a0fcad","http://resolver.tudelft.nl/uuid:9b567959-9541-45a6-bd92-94e7b1a0fcad","Chl1 helicase controls replication fork progression by regulating dNTP pools","Batté, Amandine (Leiden University Medical Center); van der Horst, Sophie C. (Leiden University Medical Center); Elmer, Mireille (TU Delft Quantum & Computer Engineering; Leiden University Medical Center); Sun, Su Ming (Leiden University Medical Center); Sharma, Sushma (Umeå University); van Leeuwen, Jolanda (University of Lausanne); Chabes, Andrei (Umeå University); van Attikum, Haico (Leiden University Medical Center)","","2022","Eukaryotic cells have evolved a replication stress response that helps to overcome stalled/collapsed replication forks and ensure proper DNA replication. The replication checkpoint protein Mrc1 plays important roles in these processes, although its functional interactions are not fully understood. Here, we show that MRC1 negatively interacts with CHL1, which encodes the helicase protein Chl1, suggesting distinct roles for these factors during the replication stress response. Indeed, whereas Mrc1 is known to facilitate the restart of stalled replication forks, we uncovered that Chl1 controls replication fork rate under replication stress conditions. Chl1 loss leads to increased RNR1 gene expression and dNTP levels at the onset of S phase likely without activating the DNA damage response. This in turn impairs the formation of RPA-coated ssDNA and subsequent checkpoint activation. Thus, the Chl1 helicase affects RPA-dependent checkpoint activation in response to replication fork arrest by ensuring proper intracellular dNTP levels, thereby controlling replication fork progression under replication stress conditions.","","en","journal article","","","","","","","","","","Quantum & Computer Engineering","","","",""
"uuid:3fe18d2d-1718-4f94-9202-5cf81f71224e","http://resolver.tudelft.nl/uuid:3fe18d2d-1718-4f94-9202-5cf81f71224e","Fatigue life and cracking characterization of engineered cementitious composites (ECC) under flexural cyclic load","Sun, Renjuan (Shandong University); Han, Lebing (Shandong Hi-Speed Engineering Test CO); Zhang, Hongzhi (Shandong University); Ge, Zhi (Shandong University); Guan, Yanhua (Shandong University); Ling, Yifeng (Shandong University); Schlangen, E. (TU Delft Materials and Environment); Šavija, B. (TU Delft Materials and Environment)","","2022","This paper presents a study on cracking characterization of engineered cementitious composites (ECC) under flexural cyclic load using digital image correlation (DIC) technique. Five stress levels, namely 0.65, 0.75, 0.8, 0.85 and 0.9 of the flexural strength, were applied. Strain map at the side surface was obtained by DIC and used to drive evolution of the midspan deflection, damage pattern, maximum crack width, number of cracks, and crack width distribution with respect to the normalized number of cycles. The stress level was found to have a significant influence on the cracking behavior of ECC under flexural cyclic load. Regardless of the applied stress level, most of the crack widths are in the range between 20 and 80 μm. In the end, a two-dimension Gauss function was used to correlate the crack width distribution with normalized number of cycle and shows satisfactory results.","Fatigue life; Engineered cementitious composites; Digital image correlation; Cracking behavior","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.","","2022-10-19","","","Materials and Environment","","",""
"uuid:a89ba010-1640-4eb0-96bc-7be543d056f9","http://resolver.tudelft.nl/uuid:a89ba010-1640-4eb0-96bc-7be543d056f9","Vision-Based Nonlinear Incremental Control for A Morphing Wing with Mechanical Imperfections","Sun, B. (TU Delft Control & Simulation); Mkhoyan, T. (TU Delft Arts & Crafts; TU Delft Aerospace Structures & Computational Mechanics); van Kampen, E. (TU Delft Control & Operations; TU Delft Control & Simulation); De Breuker, R. (TU Delft Aerospace Structures & Computational Mechanics); Wang, Xuerui (TU Delft Aerospace Structures & Computational Mechanics)","","2022","Morphing structures have acquired much attention in the aerospace community because they enable an aircraft to actively adapt its shape during flight, leading to fewer emissions and fuel consumption. Researchers have designed, manufactured, and tested a morphing wing named SmartX-Alpha, which can actively alleviate loads while achieving the optimal lift distribution. However, the widely existing mechanical imperfections can degrade the performance of the morphing wing and even lead to instabilities. To tackle these issues, this article proposes a vision-based adaptive control approach to actively compensate for mechanical imperfections. In this approach, an incremental model is constructed online to identify the system dynamics using servo commands and vision measurements, and then, nonlinear dynamic inversion control is applied based on the identified model. This data-driven control approach with visual feedback has been validated by real-world experiments on the SmartX-Alpha. The results demonstrate that the vision-based system combined with the proposed control methodology can actively compensate for mechanical imperfections with minimal adjustments to the actual system design. Compared to a controller that only uses a feedforward input-output mapping, this proposed approach improves the system performance and decreases the tracking errors by more than 62% despite disturbances. The results collectively demonstrate the effectiveness of the proposed control system, which sets a foundation for realizing morphing in next-generation aircraft.","Adaptation models; Aerodynamics; Aerospace control; datadriven control; Hysteresis; incremental model; mechanical imperfections; Morphing wing; Nonlinear dynamical systems; Shape; System dynamics; vision-based control","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.","","2023-01-09","","Control & Operations","Control & Simulation","","",""
"uuid:a64e2e12-03eb-4384-824e-276938158ad4","http://resolver.tudelft.nl/uuid:a64e2e12-03eb-4384-824e-276938158ad4","Event-triggered constrained control using explainable global dual heuristic programming for nonlinear discrete-time systems","Sun, B. (TU Delft Control & Simulation); van Kampen, E. (TU Delft Control & Simulation)","","2022","This paper develops an event-triggered optimal control method that can deal with asymmetric input constraints for nonlinear discrete-time systems. The implementation is based on an explainable global dual heuristic programming (XGDHP) technique. Different from traditional GDHP, the required derivatives of cost function in the proposed method are computed by explicit analytical calculations, which makes XGDHP more explainable. Besides, the challenge caused by the input constraints is overcome by the combination of a piece-wise utility function and a bounding layer of the actor network. Furthermore, an event-triggered mechanism is introduced to decrease the amount of computation, and the stability analysis is provided with fewer assumptions compared to most existing studies that investigate event-triggered discrete-time control using adaptive dynamic programming. Two simulation studies are carried out to demonstrate the applicability of the constructed approach. The results present that the developed event-triggered XGDHP algorithm can substantially save the computational load, while maintain comparable performance with the time-based approach.","Adaptive dynamic programming; Asymmetric input constraints; Event-triggered control; Explainable artificial intelligence; Global dual heuristic programming","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:b34ab1cd-5302-46e0-ab30-b3ec4fee9a24","http://resolver.tudelft.nl/uuid:b34ab1cd-5302-46e0-ab30-b3ec4fee9a24","Event-Triggered Adaptive Fault-Tolerant Synchronization Tracking Control for Multiple 6-DOF Fixed-Wing UAVs","Zhang, Boyang (Air Force Engineering University China); Sun, Xiuxia (Air Force Engineering University China); Liu, Shuguang (Air Force Engineering University China); Lv, Maolong (TU Delft Team Bart De Schutter); Deng, Xiongfeng (Anhui Polytechnic University)","","2022","In contrast with most existing results concerning unmanned aerial vehicles (UAVs) wherein two-degree or only attitude/longitudinal dynamics are considered, this article proposes an event-triggered cooperative synchronization fault-tolerant control (FTC) methodology for multiple fixed-wing UAVs whose dynamics are six-degree-of-freedom (DOF) with twelf-state-variables subject to actuator faults, modeling uncertainties, and external disturbances. More precisely, an event-triggering mechanism is devised to determine the time instants of updating control signals, which reduces the signal transmission burden, while saving on system resources. The Zeno phenomenon is excluded in the sense of guaranteeing that the time between two consecutive switchings is lower bounded by a positive constant. The actuator faults as well as the network induced errors are handled via the bound estimation approach and some well-defined smooth functions. By strict Lyapunov arguments, all closed-loop signals are proved to be semi-globally uniformly ultimately bounded (SGUUB) and the synchronization tracking errors of speed and attitude converge to a residual set around origin whose size can be made arbitrarily small through selecting appropriate design parameters.","Actuators; Aerodynamics; Angular velocity; Attitude control; Nonlinear dynamical systems; Synchronization; Vehicle dynamics","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.","","2023-07-01","","","Team Bart De Schutter","","",""
"uuid:85b1255b-b644-4f3b-b88c-43eb7729bc0e","http://resolver.tudelft.nl/uuid:85b1255b-b644-4f3b-b88c-43eb7729bc0e","Event-triggered intelligent critic control with input constraints applied to a nonlinear aeroelastic system","Sun, B. (TU Delft Control & Simulation); Wang, Xuerui (TU Delft Aerospace Structures & Computational Mechanics); van Kampen, E. (TU Delft Control & Simulation)","","2022","In this paper, we establish an event-triggered intelligent control scheme with a single critic network, to cope with the optimal stabilization problem of nonlinear aeroelastic systems. The main contribution lies in the design of a novel triggering condition with input constraints, avoiding the Lipschitz assumption on the inverse hyperbolic tangent function. Based on an improved weight updating criterion that eliminates the requirement of initial admissible control, the control law is obtained approximately by online training of a single critic network. The Lyapunov stability and the Zeno phenomenon of the closed-loop system are analysed. The feasibility of the established algorithm is verified by applying it to an optimal stabilization task of a nonlinear aeroelastic system. The results reveal that the developed approach can handle input-constrained optimal control problems, with performance comparable to the time-based method that updates control inputs at each instant, while reducing the computational and communication's load.","Adaptive dynamic programming; Artificial neural network; Event-triggered control; Input constraints; Nonlinear aeroelastic system","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:00547734-93e1-4eca-af9d-3d126fa5bb22","http://resolver.tudelft.nl/uuid:00547734-93e1-4eca-af9d-3d126fa5bb22","Aircraft Trajectory Prediction using ADS-B Data","YANG, X. (Student TU Delft); Sun, Junzi (TU Delft Control & Simulation); Rajan, R.T. (TU Delft Signal Processing Systems)","Louveaux, Jérôme (editor); Quitin, François (editor)","2022","Automatic Dependent Surveillance - Broadcast (ADS-B) is a surveillance technology that is used extensively in Air Traffic Control (ATC) applications. Aircraft equipped with ADS-B transponders actively broadcast navigation information such as position, altitude, and velocity, and thus ATC is able to track aircraft continuously, even in regions not covered by traditional radars. However, raw ADS-B messages are typically contaminated with noise, which is typically mitigated using model-based tracking methods to predict the trajectories. In this work, we propose and evaluate the performance of several filtering strategies for trajectory prediction on an existing open source TrajAir aircraft data set and our own data set i.e., collected by Delft university of technology (TUD). In our evaluation, we observe the standard Kalman filter cannot accurately track the aircraft trajectory, especially for sharply maneuvering targets. A fading-memory filter tracks maneuvering targets but introduces delay in estimates, and requires a trade-off between responsiveness and smoothness by target-specific parameter tuning. The Kalman filter with augmented process noise also involves similar trade-off and parameter tuning. Finally, the particle filter performs the best during target maneuvers but admits more noise during steady-state and increases computational cost. In this paper, we present various filtering techniques, and study the performance of these algorithms on the TrajAir and TUD aircraft data sets.","Filtering; ADS-B; Trajectory prediction; sensor fusion","en","conference paper","","","","","","","","","","","Signal Processing Systems","","",""
"uuid:4c8ed3e3-4238-4830-a0b0-e012229e8319","http://resolver.tudelft.nl/uuid:4c8ed3e3-4238-4830-a0b0-e012229e8319","Environmental Impact Optimisation of Flight Plans in a Fixed and Free Route network","Vergnes, Florent (ONERA Centre de Toulouse; Ecole Nationale de l’Aviation Civile (ENAC)); Bedouet, Judicaël (ONERA Centre de Toulouse); Olive, Xavier (ONERA Centre de Toulouse); Sun, Junzi (TU Delft Control & Simulation)","Lovell, Dave (editor)","2022","Efforts to minimise the environmental impact of aviation can be implemented at several levels including electric green taxiing systems, novel propulsion systems, jet fuels, improvements in aircraft efficiency and optimisation of climb profiles. In this paper, we address the optimisation of flight plans in a route network considering operational parameters and weather forecast. We implement an A* based approach to explore all possible sequences of nodes, altitudes with given wind, temperature and pressure forecasts in order to minimise total flown distance, total burnt fuel, CO2 and non-CO2 emissions, the latter being responsible for two-thirds of aviation radiative forcing. We evaluated our approach on both a network of standard routes and through free route areas, and observed that our optimised flight plans are consistent with those that have actually been filed to be flown in similar weather conditions during December 2021.","flight plan optimisation; environmental impact; green aviation; graph optimisation","en","conference paper","FAA & Eurocontrol","","","","","","","","","","Control & Simulation","","",""
"uuid:0dd836b3-87d6-4e3d-b706-296d1e1062a1","http://resolver.tudelft.nl/uuid:0dd836b3-87d6-4e3d-b706-296d1e1062a1","Assessing and Modelling Climate Optimal Flights Using Open Surveillance and Remote Sensing Data","Roosenbrand, E.J. (TU Delft Control & Simulation); Sun, Junzi (TU Delft Control & Simulation); Dedoussi, I.C. (TU Delft Aircraft Noise and Climate Effects); Stam, D.M. (TU Delft Astrodynamics & Space Missions); Hoekstra, J.M. (TU Delft Control & Simulation)","Lovell, Dave (editor)","2022","Sustainability is the biggest challenge facing the aerospace industry today. With the global number of flights expected to rise, the climate impact of aviation will continue to increase. Current research states that the rerouting of aircraft through wind-optimisation for the purpose of fuel usage minimisation and emission reduction is an effective sustainability contribution. However, these routing models only optimize for minimum fuel burn, not necessarily minimum climate impact. Flying efficiently through wind fields could mean flying through regions with higher climate impact, for example, where warming contrails are formed. This potentially forfeits the advantage of the reduced emissions from the wind-optimized route. By bringing together fields such as satellite remote sensing, atmospheric science and aircraft surveillance data, a climate optimized free routing model can be made. This paper creates a climate optimized free routing airspace model by incorporating knowledge from the aforementioned fields and existing wind-optimization models with AI and open-source tools.","Sustainability; Remote Sensing; Atmospheric Science; OpenSky; Aircraft Surveillance Data; AI; Contrails","en","conference paper","FAA & Eurocontrol","","","","","","","","","","Control & Simulation","","",""
"uuid:31a8a4d3-652f-464d-bda5-d9b5de2e9be2","http://resolver.tudelft.nl/uuid:31a8a4d3-652f-464d-bda5-d9b5de2e9be2","Platform Development of BIM-Based Fire Safety Management System Considering the Construction Site","Yang, Yapin (Hunan University); Sun, Ying (Concordia University); Chen, Mingsi (Hunan University); Zhou, Yuekuan (The Hong Kong Polytechnic University; The Hong Kong University of Science and Technology); Wang, Ran (Hunan University); Liu, Zhengxuan (TU Delft Design & Construction Management; Hunan University)","","2022","Fire at a construction site usually results in serious accidents. Therefore, fire management at the construction site is critical to decreasing possible accidents. However, conventional fire safety management can be problematic in many aspects, such as visualization, multi-stage alarm systems, and dynamic escape route optimization. To solve these issues, this paper develops a platform for a BIM-based fire safety management system that considers the construction site. The developed platform contains four subsystems: a remote monitoring subsystem, a fire visualization subsystem, a multi-stage fire alarm subsystem, and an escape route optimization subsystem. It detects the fire hazard in the early stage of the fire by the remote monitoring subsystem and transmits this information to the fire visualization subsystem for displaying. Furthermore, the multi-stage fire alarm subsystem sends warnings or alarms based on the fire’s severity. Moreover, the escape route optimization subsystem dynamically optimizes the evacuation routes by considering the actual number of people at the construction site and the potential crowding as people pass through the escapeway. Results show that this system can provide informative and on-time fire protection measures to different participants at the construction site. This study can also serve as a solution to improve fire safety management at the construction site.","construction site; fire safety management; BIM technology; escape route optimization; visualization","en","journal article","","","","","","","","","","","Design & Construction Management","","",""
"uuid:58bf9f15-1a90-43d0-90ae-3e8330290d56","http://resolver.tudelft.nl/uuid:58bf9f15-1a90-43d0-90ae-3e8330290d56","Degradation study of a reversible solid oxide cell (rSOC) short stack using distribution of relaxation times (DRT) analysis","Sampathkumar, Suhas Niggehalli (EPFL Switzerland); Aubin, Philippe (EPFL Switzerland); Couturier, Karine (CEA Grenoble); Sun, Xiufu (Technical University of Denmark); Sudireddy, Bhaskar Reddy (Technical University of Denmark); Diethelm, Stefan (EPFL Switzerland); Pérez-Fortes, Mar (EPFL Switzerland); van Herle, Jan (EPFL Switzerland)","","2022","Reversible solid oxide cells (rSOC) can convert excess electricity to valuable fuels in electrolysis cell mode (SOEC) and reverse the reaction in fuel cell mode (SOFC). In this work, a five – cell rSOC short stack, integrating fuel electrode (Ni-YSZ) supported solid oxide cells (Ni-YSZ || YSZ | CGO || LSC-CGO) with an active area of 100 cm2, is tested for cyclic durability. The fuel electrode gases of H2/N2:50/50 and H2/H2O:20/80 in SOFC and SOEC mode, respectively, are used during the 35 reversible operations. The voltage degradation of the rSOC is 1.64% kh−1 and 0.65% kh−1 in SOFC and SOEC mode, respectively, with fuel and steam utilisation of 52%. The post-cycle steady-state SOEC degradation of 0.74% kh−1 suggests improved lifetime during rSOC conditions. The distribution of relaxation times (DRT) analysis suggests charge transfer through the fuel electrode is responsible for the observed degradation.","Reversible solid oxide cell; rSOC; Distribution of relaxation times; DRT; rSOC degradation","en","journal article","","","","","","","","","","","","","",""
"uuid:45ae67e9-888d-4fef-9bfc-552c782539c5","http://resolver.tudelft.nl/uuid:45ae67e9-888d-4fef-9bfc-552c782539c5","OpenAP.top: Open Flight Trajectory Optimization for Air Transport and Sustainability Research","Sun, Junzi (TU Delft Control & Simulation)","","2022","Trajectory optimization has been an active area of research for air transport studies for several decades. But almost all flight optimizers proposed in the literature remain close-sourced, which presents a major disadvantage for the advancement of scientific research. This optimization depends on aircraft performance models, emission models, and operational constraints. In this paper, I present a fully open trajectory optimizer, OpenAP.top, which offers researchers easy access to the complex but efficient non-linear optimal control approach. Full flights can be generated without specifying flight phases, and specific flight segments can also be independently created. The optimizer adapts to meteorological conditions and includes conventional fuel and cost index objectives. Based on global warming and temperature potentials, its climate objectives form the basis for climate optimal air transport studies. The optimizer’s performance and uncertainties under different factors like varying mass, cost index, and wind conditions are analyzed. Overall, this new optimizer brings a high performance for optimal trajectory generations by providing four-dimensional and wind-enabled full-phase optimal trajectories in a few seconds. View Full-Text","trajectory optimization; optimal control; direct collocation; climate objective functions; sustainable aviation","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:1c701e47-ed30-41c1-9300-aa6e586d2f6b","http://resolver.tudelft.nl/uuid:1c701e47-ed30-41c1-9300-aa6e586d2f6b","Designing Recurrent and Graph Neural Networks to Predict Airport and Air Traffic Network Delays","Sun, Junzi (TU Delft Control & Simulation); Dijkstra, T.L.E. (Student TU Delft); Aristodemou, K. (Student TU Delft); Buzeţelu, V.S. (Student TU Delft); Falat, T. (Student TU Delft); Hogenelst, T.G. (Student TU Delft); Prins, N. (Student TU Delft); Slijper, B.C. (Student TU Delft)","Lovell, Dave (editor)","2022","In this paper, we propose open machine learning models that can provide airport delay predictions in a network with an error of around or less than five minutes. Due to the complexity of different components of air traffic networks, traditional flight performance model-based predictions fall short when dealing with numerous flights and often are not able to deal with delays that propagate among airports in a network. In this study, we employ three different machine learning models to predict delays at three different scopes: individual flights, airports, and the network of airports. Consequently, we tested three approaches with different levels of complexity, including statistical regression models, recurrent neural networks, and spatial-temporal graph attention neural networks. We conduct experiments for all three types of models using the Eurocontrol research data archive. After training and testing with two years of data covering the top 50 European airports, our models produce prediction errors of around or less than 5 minutes with look-ahead time up to 3 hours. These metrics have shown a significant advancement compared to existing prediction models. We also openly share this model to support open science in aviation.","flight delay; airport delay propagation; random forest; recurrent neural network; graph attention neural network","en","conference paper","FAA & Eurocontrol","","","","","","","","","","Control & Simulation","","",""
"uuid:bf5c4745-4270-4304-a686-095058f5a4e6","http://resolver.tudelft.nl/uuid:bf5c4745-4270-4304-a686-095058f5a4e6","A human-centric machine learning based personalized route choice prediction in navigation systems","Sun, Bingrong (University of Virginia); Gong, Lin (University of Virginia); Shim, J. (TU Delft Transport and Planning); Jang, Kitae (Korea Advanced Institute of Science and Technology); Park, B. Brian (University of Virginia); Wang, Hongning (University of Virginia); Hu, Jia (Tongji University)","","2022","Real-world route navigation data indicate that nontrivial portion of drivers do not prefer the system-recommended best routes. Current navigation systems have simplified assumptions about drivers’ route choice preferences and do not adequately accommodate drivers’ heterogeneous route choice preferences, mainly because of: (i) difficulty in acquiring exogenous criteria (e.g., sociodemographic information) that are typically used to differentiate drivers’ preferences in behavioral modeling; and (ii) difficulty in capturing preference of individuals due to limited preference data at the individual level. To address these, this paper introduced a human-centric machine learning technique named Multi-Task Linear Classification Model Adaption (MT-LinAdapt). It can capture drivers’ common aspects of route choice preferences and yet adapts to each driver’s own preference. In addition, any evolvement of individual drivers’ preferences can be simultaneously integrated to update the common preference for further individual drivers’ preference adaptation. This paper evaluated MT-LinAdapt against two state-of-the-art route recommendation strategies including an aggregate-level and an individual-level data-based strategies, which are categorized based on the data used for modeling. With a real-world dataset containing 30,837 drivers’ navigation usage data in Daegu City, South Korea, MT-LinAdapt was compared to existing strategies for its performance at different levels of data availability, and showed at least the same performance with existing strategies when minimum preference data is available and achieves up to 7% higher prediction accuracy as more data becomes available. Higher prediction accuracies are expected to bring better user satisfaction and compliance rates which can further help with transportation system control and management strategies.","Intelligent transportation system; machine learning; personalized choice prediction; route choice; traveler information system","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.","","2023-07-01","","","Transport and Planning","","",""
"uuid:13d00ad1-4c3a-4b13-a4c3-cf77e8ec4a87","http://resolver.tudelft.nl/uuid:13d00ad1-4c3a-4b13-a4c3-cf77e8ec4a87","Application of YOLOv4 Algorithm for Foreign Object Detection on a Belt Conveyor in a Low-Illumination Environment","Chen, Yiming (Shandong Zhongheng Optoelectronic Technology Co.); Sun, Xu (China University of Mining and Technology); Xu, Liang (China University of Mining and Technology); Ma, Sencai (China University of Mining and Technology); Li, Jun (China University of Mining and Technology); Pang, Y. (TU Delft Transport Engineering and Logistics); Cheng, Gang (China University of Mining and Technology)","","2022","The most common failures of belt conveyors are runout, coal piles and longitudinal tears. The detection methods for longitudinal tearing are currently not particularly effective. A key study area for minimizing longitudinal belt tears with the advancement of machine learning is how to use machine vision technology to detect foreign items on the belt. In this study, the real-time detection of foreign items on belt conveyors is accomplished using a machine vision method. Firstly, the KinD++ low-light image enhancement algorithm is used to improve the quality of the captured low-quality images through feature processing. Then, the GridMask method partially masks the foreign objects in the training images, thus extending the data set. Finally, the YOLOv4 algorithm with optimized anchor boxes is combined to achieve efficient detection of foreign objects in belt conveyors, and the method is verified as effective.","belt conveyor; KinD++ algorithm; low-light enhancement; machine vision; YOLOv4 algorithm","en","journal article","","","","","","","","","","","Transport Engineering and Logistics","","",""
"uuid:c9d55bd9-c248-42e4-af84-8bfb93bd91ac","http://resolver.tudelft.nl/uuid:c9d55bd9-c248-42e4-af84-8bfb93bd91ac","Effect of crack width and wet-dry cycles on the chloride penetration resistance of engineered cementitious composite (ECC)","Sun, Renjuan (Shandong University); Lu, Wei (Shandong University); Tawfek, Abdullah M. (Shandong University; Sana'a University); Guan, Yanhua (Shandong University); Hu, Xinlei (Shandong University); Zhang, Hongzhi (Shandong University); Ling, Yifeng (Shandong University); Šavija, B. (TU Delft Materials and Environment)","","2022","The resistance of cracked ECC against chloride ingress is mainly governed by the accumulated crack width of all the cracks rather than the maximum width of multiple cracks. However, most studies focus on the influence of a single fine crack","Engineered Cementitious Composites; Chloride penetration resistance; Crack width; Wet-dry cycles; Chloride binding isotherm; Microstructure","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.","","2023-09-01","","","Materials and Environment","","",""
"uuid:85119dc9-abb6-4cf7-af5c-f122d7cc2f8e","http://resolver.tudelft.nl/uuid:85119dc9-abb6-4cf7-af5c-f122d7cc2f8e","Global Civil Aviation Emissions Estimates for 2017–2020 Using ADS-B Data","Domingos de Azevedo Quadros, F. (TU Delft Aircraft Noise and Climate Effects); Snellen, M. (TU Delft Control & Operations); Sun, Junzi (TU Delft Control & Simulation); Dedoussi, I.C. (TU Delft Aircraft Noise and Climate Effects)","","2022","Aviation is a growing source of atmospheric emissions impacting the Earth’s climate and air quality. Comprehensive assessments of the environmental impact of this industry require up-to-date, spatially resolved, and speciated emissions inventories. We develop and evaluate the first such estimate of global emissions from aircraft operations for the years 2017–2020. Aircraft activity data, based on flights registered by networks of aircraft Automatic Dependent Surveillance–Broadcast (ADS-B) telemetry receivers, are used together with the Base of Aircraft Data (BADA) 3.15 aircraft performance model and the International Civil Aviation Organization Engine Emissions Databank to estimate spatially resolved fuel burn and emissions of CO2, H2O, NOx (NO+NO2), SOx (SO2+SO2−4), CO, unburnt hydrocarbons (HC), and nonvolatile particulate matter (nvPM). We calculate that 937 Tg of CO2 and 4.62 Tg of NOx were emitted by aircraft in 2019, and quantify the evolution of the fleet average emission indices over time. Owing to impacts from COVID-19, we estimate a 48% lower fuel burn, resulting in 463 Tg less CO2 and 2.29 Tg less NOx emitted in 2020 than what would be otherwise expected. We conclude that ADS-B is a viable source of data to generate global emissions estimates in a timely and transparent manner for monitoring and assessing aviation’s atmospheric impacts.","","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.","","2023-06-05","","Control & Operations","Aircraft Noise and Climate Effects","","",""
"uuid:f4979f22-0319-4394-9a08-b18c341822d0","http://resolver.tudelft.nl/uuid:f4979f22-0319-4394-9a08-b18c341822d0","Carriage interior noise-based inspection for rail corrugation on high-speed railway track","Wei, Zilong (China Academy of Railway Sciences); Sun, Xianfu (China Academy of Railway Sciences); Yang, Fei (China Academy of Railway Sciences); Ke, Zaitian (China Academy of Railway Sciences); Lu, Tao (Southwest Jiaotong University); Zhang, P. (TU Delft Railway Engineering); Shen, C. (TU Delft Railway Engineering)","","2022","The presence of rail corrugation enlarges the wheel-rail impact and exacerbates the failure of track components, and the situation becomes even worse under high train speed, which promotes the urgent need for an efficient and easily accessible inspection method. Conventional diagnosis approaches such as axle box acceleration (ABA) and image recognition measurements, however, require complex instrumentations on the running gear, restricting their applications on a wide range of operational trains. In this study, we investigate the capability of carriage interior noise in diagnosing rail corrugation on the high-speed railway (HSR). For this purpose, train-borne vibration & noise measurements were integrated with in-situ rail surface irregularity tests, to extract the characteristic carriage interior responses induced by rail corrugation. The measurements were conducted on two HSR tracks with different corrugation geometries, and the time–frequency distributions of interior noise were identified under different train speeds and with different track radii. Afterward, an interior noise-based inspection algorithm was proposed by proper correlation of the gained data, and was then demonstrated on a third HSR track with an unknown rail surface condition. The comparison between the proposed inspection algorithm and the widely-recognized ABA measurements indicates that the interior noise succeeded in identifying the position, typical wavelength and severity of rail corrugation under varying train speeds. The work advances a cost-effective and easily accessible way for the condition monitoring of railway tracks.","Carriage interior noise; Rail corrugation; High-speed railway; Acoustic inspection","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.","","2022-12-29","","","Railway Engineering","","",""
"uuid:93042519-f148-4fbe-b8af-8d893c64c8f2","http://resolver.tudelft.nl/uuid:93042519-f148-4fbe-b8af-8d893c64c8f2","Wind velocity field estimation from aircraft derived data using Gaussian process regression","Marinescu, Marius (King Juan Carlos University); Olivares, Alberto (King Juan Carlos University; Universidad Rey Juan Carlos); Staffetti, Ernesto (King Juan Carlos University; Universidad Rey Juan Carlos); Sun, Junzi (TU Delft Control & Simulation)","","2022","Wind velocity field knowledge is crucial for the future air traffic management paradigm and is key in many applications, such as aircraft performance studies. This paper addresses the problem of spatio-temporal windc velocity field estimation. The north and east wind components within a given air space are estimated as a function of time. Both wind velocity field reconstruction in space for a past or present time instant and short-term prediction are performed. Wind data are obtained indirectly from the states of the aircraft broadcast by the Mode-S and ADS-B aircraft surveillance systems. The Gaussian process regression method, which is a flexible and universal estimator, is employed to solve both problems. Under general conditions, the method is statistically consistent, meaning that the method converges to the ground truth when increasingly more data are available, which is especially interesting, since aircraft data availability is expected to grow in the future through the deployment of the European System-Wide Information Management. Besides estimation, the Gaussian process regression method provides the probability distribution of any particular estimate, allowing confidence intervals to be computed. Moreover, the spatial modelling is performed using raw data without relying on grids and estimation can be performed at any spatio-temporal location. Furthermore, since the training phase of the method described in this paper is fast, requiring less than 5 minutes on a standard desktop computer, it can be used online to continuously track the state of the wind velocity field, thus allowing for data assimilation. In the case study presented in this paper, the Gaussian process regression method is tested on different days with different wind intensities. The available data set is split into several training and testing data sets, which are used to check the consistency of the results of wind velocity field reconstruction and prediction. Finally, the Gaussian process regression method is validated using the European Centre for Medium-Range Weather Forecasts ERA5 meteorological reanalysis data. The obtained results show that Gaussian process regression can be used to reliably estimate the wind velocity field from aircraft derived data.","","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:83270c60-8335-4bf4-ab17-73295c7b6690","http://resolver.tudelft.nl/uuid:83270c60-8335-4bf4-ab17-73295c7b6690","ArduPilot-Based Adaptive Autopilot: Architecture and Software-in-The-Loop Experiments","Baldi, S. (TU Delft Team Bart De Schutter; Southeast University); Sun, Danping (Wuhan Textile University; Hubei Electrical Machinery and Control System Engineering Technology Research Center); Xia, Xin (Southeast University); Zhou, Guopeng (Hubei Electrical Machinery and Control System Engineering Technology Research Center); Liu, Di (Southeast University; Rijksuniversiteit Groningen)","","2022","This article presents an adaptive method for ArduPilot-based autopilots of fixed-wing unmanned aerial vehicles (UAVs). ArduPilot is a popular open-source unmanned vehicle software suite. We explore how to augment the PID loops embedded inside ArduPilot with a model-free adaptive control method. The adaptive augmentation, adopted for both attitude and total energy control, uses input/output data without requiring an explicit model of the UAV. The augmented architecture is tested in a software-in-The-loop UAV platform in the presence of several uncertainties (unmodeled low-level dynamics, different payloads, time-varying wind, and changing mass). The performance is measured in terms of tracking errors and control efforts of the attitude and total energy control loops. Extensive experiments with the original ArduPilot, the proposed augmentation, and alternative autopilot strategies show that the augmentation can significantly improve the performance for all payloads and wind conditions: The UAV is less affected by wind and exhibits more than 70% improved tracking, with more than 7% reduced control effort.","ArduPilot; attitude control; autopilot; model-free adaptive control; total energy control; unmanned aerial vehicle (UAV)","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.","","2023-07-01","","","Team Bart De Schutter","","",""
"uuid:fd2252b4-7110-445c-967b-cbdaaf497b94","http://resolver.tudelft.nl/uuid:fd2252b4-7110-445c-967b-cbdaaf497b94","Research Progress on Convective Heat Transfer Characteristics of Supercritical Fluids in Curved Tube","Liu, Xinxin (Henan Agricultural University); Li, Shuoshuo (Henan Agricultural University); Liu, Liang (Henan Agricultural University); He, Chao (Henan Agricultural University); Sun, Zhuang (University of Tokyo); Özdemir, F. (TU Delft Energy Technology); Aziz, Muhammad (University of Tokyo); Kuo, Po-Chih (University of Tokyo)","","2022","Because of their compact structure, ease of processing and higher heat transfer coefficient, curved-tube heat exchangers are widely applied in various industry applications, such as nuclear power systems, solar-powered engineering, aircraft engine cooling systems and refrigeration and cryogenic systems. Accurate knowledge about the heat transfer characteristics of the supercritical fluids in the tube is critical to the design and optimization of a curved-tube heat exchanger. The available literature indicates that the flow of supercritical fluids flowing in curved tubes affected by the dual effects of the buoyancy force and centrifugal force is more complex compared to straight tubes. Therefore, to obtain insight into their unique characteristics and further research progress, this paper presents a comprehensive review of available experimental and numerical research works on fluids at supercritical pressure flowing in curved tubes. Overall, the secondary flow caused by the curvature enhances the heat transfer and delays the heat transfer deterioration, but it also causes a non-uniform heat transfer distribution along the circumferential direction, and the strengthening performance of the curved tube is damaged. Compared with the more mature theories regarding straight tubes, the flow structure, the coupling mechanism of buoyancy and centrifugal force, and the general heat transfer correlation of supercritical fluids in a curved tube still urgently need to be further studied. Most importantly, studies on the suppression of heat transfer oscillations and heat transfer inhomogeneities specific to curved tubes are scarce. Considering the current status and shortcomings of existing studies, some study topics for supercritical fluids in a curved tube are proposed","heat transfer characteristics; supercritical fluids; curved tube; heat transfer enhancement; buoyancy force; centrifugal force","en","journal article","","","","","","","","","","","Energy Technology","","",""
"uuid:d5560d38-7c94-4b92-9263-37da4d931367","http://resolver.tudelft.nl/uuid:d5560d38-7c94-4b92-9263-37da4d931367","Experimental and theoretical study on residual ultimate strength after impact of CF/PEEK-titanium hybrid laminates with nano-interfacial enhancement","Ji, C. (TU Delft Structural Integrity & Composites; Harbin Institute of Technology (Shenzen)); Hu, Jiqiang (Harbin Institute of Technology); Sadighi, M. (TU Delft Structural Integrity & Composites); Alderliesten, R.C. (TU Delft Structural Integrity & Composites); Wang, Bing (Harbin Institute of Technology); Sun, Yuguo (Harbin Institute of Technology)","","2022","Fiber metal laminates (FMLs) provide a reliable approach for achieving lightweight in high-speed aerospace vehicles. However, the weak interfacial properties between metals and composites could significantly affect the deformation and failure modes of FMLs. In this paper, the low-velocity impact responses and damage mechanisms of CF/PEEK-Ti hybrid laminates with nano-interfacial enhancement by multi-walled carbon nanotubes (CNTs) were characterized and analyzed. The post-impact residual tensile strengths (RTS) were investigated experimentally using quasi-static uniaxial tests combined with digital image correlation, and were evaluated theoretically by developing an analytical prediction model that considers the internal thermal stress and dent geometry. Results show that the initial delamination thresholds of force and displacement during impact can be effectively increased via interfacial enhancement of CNT network. By using a 5% decrease in RTS retention rate as a criterion for damage tolerance, a significant strength decrease starts to appear at 3 J for the sandblasted-only laminates, which is improved to 10 J for the laminates with nano-interfacial enhancement. The proposed unified constitutive model can yield an acceptable prediction for RTS and failure strain of the hybrid laminate after impact, providing a guidance for the structural design and engineering applications of FMLs.","","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.","","2023-06-01","","","Structural Integrity & Composites","","",""
"uuid:fe41d6ad-421b-4678-9b7a-d841b79415e7","http://resolver.tudelft.nl/uuid:fe41d6ad-421b-4678-9b7a-d841b79415e7","An integrated scenario-based measuring for transportation resilience: A case study of Pazhou, Guangzhou, Greater Bay Area","Lu, P. (TU Delft Landscape Architecture; South China University of Technology); Sun, Yimin (South China University of Technology); Nijhuis, S. (TU Delft Landscape Architecture)","","2022","","","en","poster","","","","","","","","","","","Landscape Architecture","","",""
"uuid:83abe451-ae20-4e53-8704-fd4a40f2b486","http://resolver.tudelft.nl/uuid:83abe451-ae20-4e53-8704-fd4a40f2b486","Toward a resilient coastal city: performance assessment for adaptive solutions of green-gray-blue infrastructure","Lu, P. (TU Delft Landscape Architecture; South China University of Technology); Sun, Yimin (South China University of Technology); Nijhuis, S. (TU Delft Landscape Architecture)","","2022","","","en","poster","","","","","","","","","","","Landscape Architecture","","",""
"uuid:73a8616f-06ef-4b10-861d-ffba93bb0d17","http://resolver.tudelft.nl/uuid:73a8616f-06ef-4b10-861d-ffba93bb0d17","Scenario-based coastal resilience assessment of Green-Blue-Gray infrastructure: A case study of Marine City, Shenzhen, Greater Bay Area","Lu, P. (TU Delft Landscape Architecture; South China University of Technology); Sun, Yimin (South China University of Technology); Nijhuis, S. (TU Delft Landscape Architecture)","","2022","","","en","poster","","","","","","","","","","","Landscape Architecture","","",""
"uuid:2c45fb56-f2ef-416c-ba59-5fa2217077e7","http://resolver.tudelft.nl/uuid:2c45fb56-f2ef-416c-ba59-5fa2217077e7","Evading the Public Eye: On Astroturfing in Open Aviation Data †","Strohmeier, Martin (OpenSky Network, Burgdorf; Cyber-Defence Campus, Zurich); Olive, Xavier (OpenSky Network, Burgdorf; Université de Toulouse); Sun, Junzi (TU Delft Control & Simulation)","","2022","The usage of large private and business jets, from those owned by Elon Musk to Kylie Jenner and Bernard Arnault, has recently attracted considerable attention in many countries. Enabled by open and crowdsourced aircraft tracking systems based on the automatic dependent surveillance–broadcast protocol, the aircraft and their owners have been scrutinized. While the underlying technology is not novel and its privacy issues have been discussed for years, the increased attention has led to the backlash against open tracking data and, consequently, a scramble to find possible solutions to hide private jets from the public eye. In this paper, we analyze two such methods, which have not yet been discussed previously in the literature: blocking requests to web tracking platforms and malicious editing of crowdsourced databases. We draw on data from the OpenSky Network and illustrate the futility of such approaches. Finally, we outline the type of stakeholders and aircraft deploying such methods, as well as demonstrate the level of environmental impact that might have otherwise been missed by the public.","ADS-B; astroturfing; business jets; flight environmental cost; OpenSky Network; privacy; tracking aircraft emissions","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:d3a315f2-9216-4014-96c3-a32bedf02f69","http://resolver.tudelft.nl/uuid:d3a315f2-9216-4014-96c3-a32bedf02f69","Environmental Footprint of Private and Business Jets †","Sun, Junzi (TU Delft Control & Simulation; OpenSky Network, Burgdorf); Olive, Xavier (OpenSky Network, Burgdorf); Strohmeier, Martin (OpenSky Network, Burgdorf)","","2022","Civil aviation contributes to rising global greenhouse gas emissions. Flights carried out by private and business jets are only a very small fraction of commercial passenger flights. However, these private flights are extremely environmentally inefficient and account for the most emissions per passenger in the aviation sector. While the commercial aviation sector has been under increased scrutiny by environmentalists for years, the footprint of private and business jets has entered the public eye only very recently. Social media provides new ways for sharing individual private flights, but the large-scale analysis of private jet flights and their emissions has been lacking until now. To better inform this discussion, we use open and large-scale flight data collected by the OpenSky Network over fours years and apply the OpenAP model in order to estimate the emissions of around 250 private jets. The total carbon emissions is found to be between 0.45 and 0.5 megatonnes. The yearly emissions from these selected jets is equivalent to 40,000 global inhabitant emissions. In our analysis, we provide further insight into private jet emissions and raise awareness about the emission inequalities in the current aviation system.","ADS-B; business jets; emissions; OpenSky network; private jets","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:d9fd33e5-b517-4abf-b03a-610b4274cf0b","http://resolver.tudelft.nl/uuid:d9fd33e5-b517-4abf-b03a-610b4274cf0b","Evaluating Aviation Emission Inefficiencies and Reduction Challenges with Electric Flights","Sun, Junzi (TU Delft Control & Simulation); Olive, Xavier (ONERA Centre de Toulouse); Delahaye, Daniel (Ecole Nationale de l’Aviation Civile (ENAC))","","2022","Inefficiencies in flight operations, like deviations and non-optimal flight speed or altitude, are directly linked to flight emission inefficiencies. Quantifying these emission inefficiencies and studying potential mitigation strategies is certainly beneficial for the sustainability of the aviation industry. In this paper, we analyze emission inefficiencies in Dutch and French airspaces using flight data from 2019. The emission inefficiency analysis quantifies the excess carbon emissions for each flight by comparing its emissions with a set of optimal alternative trajectories. We find that around 19% of excess emissions existed in 2019 within the airspace of interest. We also study the potential reduction of emissions by replacing short-range flights with electric aircraft. We propose a simple electric aircraft energy model and relate that to emissions in electric generations in different countries. We find that besides the significant increase in air traffic demand caused by the limited capacities of electric flights, the emissions caused by electricity generation cannot be neglected. Significant reductions can only be achieved when emissions caused by electricity generation are low, as is the case currently in France. However, more emissions can be indirectly generated if the electricity used to power the future electric aircraft is itself produced from high emission sources, as is the case currently in the Netherlands. The paper also provides further insights and recommendations on the data sources, research approach, and future research for aviation sustainability.","flight emission; data analysis; emission inefficiencies; trajectory optimization; electric flight","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.","","2023-05-10","","","Control & Simulation","","",""
"uuid:edae6ce7-e633-44d3-99f4-f2f2f0ce0193","http://resolver.tudelft.nl/uuid:edae6ce7-e633-44d3-99f4-f2f2f0ce0193","Examining Contrail Formation Models with Open Flight and Remote Sensing Data","Roosenbrand, E.J. (TU Delft Control & Simulation); Sun, Junzi (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2022","One of the biggest challenges facing the aerospace industry today is its sustainability. As the number of flights is expected to rise globally, aviation’s climate impact will continue to increase. Current research has extensively addressed the rerouting of aircraft through wind-optimization in order to minimize fuel burn and emissions. Such optimization is currently implemented for flight planning. Although this strategy is optimized for fuel burn and emissions, it does not necessarily minimize the overall climate impact. Navigating optimally through wind fields could mean flying through regions with a higher climate impact, where warming contrails are formed. This can occur when contrails trap outgoing terrestrial radiation and so contribute to global warming. This warming contrail creation could potentially forfeit the climate gain of the reduced emissions from the wind-optimized route. In order to implement such a climate-optimized routing model, knowledge about the atmospheric conditions under which contrails form is required. One existing theorem is the Schmidt-Appleman Criterion, which uses the air temperature, relative humidity and ambient air pressure to determine whether contrail formation is possible. In addition, the ice-supersaturation criterion model indicates contrail persistence. In this paper, multiple open data sources are used to examine the use of this established criterion, to evaluate the appropriateness of these data sources for future use in a climate-optimized routing model. Based on the obtained results, we show that, with these data sources, the combination of Schmidt-Appleman and the ice-supersaturation criterion can produce a more reliable determination of contrail formation. The results can be used for an improved unified and data-driven model for the purposes of climate-optimized routing.","Sustainability; Contrails; Remote Sensing; Atmospheric Science; OpenSky; Aircraft Surveillance Data","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.","","2023-05-10","","","Control & Simulation","","",""
"uuid:8c778d76-deab-41e2-b0da-806fcb692083","http://resolver.tudelft.nl/uuid:8c778d76-deab-41e2-b0da-806fcb692083","ZVS Turn-on integrated Triangular Current Mode Three-phase PFC for EV On-board Chargers","Sun, Jian (Student TU Delft); Wu, Y. (TU Delft DC systems, Energy conversion & Storage); Soeiro, Thiago B. (European Space Agency (ESA)); Qin, Z. (TU Delft DC systems, Energy conversion & Storage); Bauer, P. (TU Delft DC systems, Energy conversion & Storage)","","2022","An efficient, compact and lightweight three-phase AC-DC power factor correction (PFC) converter becomes a necessity for electric vehicles (EVs) On-board chargers (OBCs) in conventional grid-to-vehicle (G2V) and vehicle-to-grid (V2G) charging methods. The commercially available OBCs have very limited power density despite the moderate efficiency under specific power levels. In this paper, the integrated triangular current mode (iTCM) control is implemented to improve the power density (kW/L) and specific power (kW/kg) of the three-phase PFC converter stage while maintaining high efficiency. Zero voltage switching (ZVS) turn-on is realized in the iTCM control with a higher switching frequency to reduce the LCL filter size without sacrificing efficiency. By adding an LC branch between the bridge leg and mid-point of the DC link, the high-frequency and low-frequency currents are split to minimize the inductor loss and to derive a better inductor design. Analytical modeling and simulation in PLECS are conducted to verify the idea of iTCM. The capacitor-current feedback active damping method is implemented to prevent instability from the LC and LCL filters. The design of an 11kW three-phase AC-DC PFC converter, including the input LCL filter, achieves an efficiency of 98.81%, a power density of 12.46 kW/L and a specific power per weight of 1.87 kW/kg. The proposed three-phase iTCM control is benchmarked in a 3 kW SiC MOSFET-based AC-DC converter.","On-board chargers; power factor correction; integrated triangular current mode; zero voltage switching","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","","","DC systems, Energy conversion & Storage","","",""
"uuid:3df04653-b8fd-4684-aa6d-bb2ec614e621","http://resolver.tudelft.nl/uuid:3df04653-b8fd-4684-aa6d-bb2ec614e621","OpenSky Report 2022: Evaluating Aviation Emissions Using Crowdsourced Open Flight Data","Sun, Junzi (TU Delft Control & Simulation); Basora, Luis (Université de Toulouse); Olive, Xavier (Université de Toulouse); Strohmeier, Martin (University of Oxford; Armasuisse); Schafer, Matthias (Technische Universität Kaiserslautern); Martinovic, Ivan (University of Oxford); Lenders, Vincent (Armasuisse)","","2022","The environmental impact of aviation has become the focus of increased concerns for policymakers around the world. The recent pandemic provided many interesting case studies on the impact of aviation on the environment. Following the initial COVID-19 containment measures and hard lockdowns, the sharp decrease in aircraft movements caused a measurably improved air quality worthy of further study.The OpenSky Network has acted as an important open data source for aviation research since 2013. In this paper, we analyze one year of fine-grained pre-COVID air traffic trajectories (comprising the entire year 2018) to estimate fuel consumption and pollutant emissions in the aviation industry. We compare this large-scale big data processing approach to a reduced model approach based solely on global commercial aircraft movement schedules collected from airlines and airports, aggregated by a commercial provider.Our study quantifies the impact of commercial aviation on global emissions. The numbers reveal that aviation's CO2 emissions contribute to 2% of global emissions and that commercial aviation contribution remains a proxy for countries' wealth.","","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.","","2023-06-01","","","Control & Simulation","","",""
"uuid:c691656a-7a30-4c1a-b53f-a11ec824afbd","http://resolver.tudelft.nl/uuid:c691656a-7a30-4c1a-b53f-a11ec824afbd","Combined MPC and reinforcement learning for traffic signal control in urban traffic networks","Remmerswaal, Willemijn (Student TU Delft); Sun, D. (TU Delft Team Bart De Schutter); Jamshidnejad, A. (TU Delft Control & Simulation); De Schutter, B.H.K. (TU Delft Delft Center for Systems and Control)","Barbu, Marian (editor); Solea, Razvan (editor)","2022","In general, the performance of model-based controllers cannot be guaranteed under model uncertainties or disturbances, while learning-based controllers require an extensively sufficient training process to perform well. These issues especially hold for large-scale nonlinear systems such as urban traffic networks. In this paper, a new framework is proposed by combining model predictive control (MPC) and reinforcement learning (RL) to provide desired performance for urban traffic networks even during the learning process, despite model uncertainties and disturbances. MPC and RL complement each other very well, since MPC provides a sub-optimal and constraint-satisfying control input while RL provides adaptive control laws and can handle uncertainties and disturbances. The resulting combined framework is applied for traffic signal control (TSC) of an urban traffic network. A case study is carried out to compare the performance of the proposed framework and other baseline controllers. Results show that the proposed combined framework outperforms conventional control methods under system uncertainties, in terms of reducing traffic congestion.","","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.","","2023-05-08","","Delft Center for Systems and Control","Team Bart De Schutter","","",""
"uuid:5223e1d2-e876-4584-a220-21e348603c1c","http://resolver.tudelft.nl/uuid:5223e1d2-e876-4584-a220-21e348603c1c","Preliminary Design and Capacity Study of Automatic Dependent Surveillance for Drones","Vlaskin, A. (TU Delft Control & Simulation); Sun, Junzi (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2022","The consumer drone sector is expected to grow rapidly in the coming decades. In Europe alone, some predictions show as many as seven million drones will be flying by 2050. This poses a challenge for surveillance. In this paper, we study an Automatic Dependent Surveillance system concept similar to the one for current aircraft surveillance, which allows the drone to broadcast information about itself without external input. The study’s main contents are threefold. The first consists of recommendations made based on literature. Then, we perform a simulation approach to examine system capacity and related constraints through a sensitivity study is done. Finally, a hardware proof-of-concept, consisting of inexpensive and simple off-theshelf components, is built and tested. We have demonstrated that such a system is indeed feasible. However, the carrier frequency and code allocation must be changed to prevent interference with the current aircraft’s automatic surveillance system. The simulation and capacity study tests the limitation of such a system in high-density scenarios, and provide recommendation for additional work on hardware, format, and modulation techniques to enable such a system. Finally, the hardware test shows that an inexpensive commercial-of-the-shelf implementation with a range of approximately 200 meters is possible, on hardware drawing less than five Watts of power.","Automatic Dependent Surveillance; UAV; U-Space; ADS-B","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.","","2023-05-10","","","Control & Simulation","","",""
"uuid:588d5ca6-5782-4030-979d-a38cb8c567f8","http://resolver.tudelft.nl/uuid:588d5ca6-5782-4030-979d-a38cb8c567f8","Resilience Assessment of Chemical Process Systems under uncertain Disruptions based on Catastrophe Theory (CT) and Dynamic Bayesian Network (DBN)","Sun, H. (TU Delft Safety and Security Science; China University of Petroleum (East China)); Wang, Haiqing (China University of Petroleum (East China)); Yang, M. (TU Delft Safety and Security Science); Reniers, G.L.L.M.E. (TU Delft Safety and Security Science; Universiteit Antwerpen; Katholieke Universiteit Leuven)","","2022","Due to the rapid development of technology, process systems become dynamic, automated, and complex, resulting in the strong interdependence and interaction among components and ensuring system safety by conventional methods a challenge. Compared with traditional risk assessment methods, resilience assessment is a more appropriate method for ensuring the safety of process systems under uncertain disruptions. Resilience refers to absorbing and adapting to changing conditions and recovering from disruptions. This paper presents a comprehensive assessment model that combines the catastrophe theory (CT) with the dynamic Bayesian network (DBN) to measure dynamic resilience. Firstly, the CT is employed to quantify the intensity of disruptions. Subsequently, the performance response function (PRF) of the system is determined by DBN. A resilience metric is then introduced to measure system resilience under uncertain disruptions. The method is demonstrated through a release prevention barrier system.","","en","journal article","","","","","","","","","","","Safety and Security Science","","",""
"uuid:a03ab1c9-bc1f-4a62-b1d2-20783b4d60d4","http://resolver.tudelft.nl/uuid:a03ab1c9-bc1f-4a62-b1d2-20783b4d60d4","An online data driven fault diagnosis and thermal runaway early warning for electric vehicle batteries","Sun, S.Z. (TU Delft DC systems, Energy conversion & Storage; Beijing Institute of Technology); Wang, Zhenpo (Beijing Institute of Technology); Liu, Peng (Beijing Institute of Technology); Qin, Z. (TU Delft DC systems, Energy conversion & Storage); Chen, Yong; Han, Yang (The University of Manchester); Wang, Peng (Zhejiang Geely Automobile Research Institute Co); Bauer, P. (TU Delft DC systems, Energy conversion & Storage)","","2022","Battery fault diagnosis is crucial for stable, reliable, and safe operation of electric vehicles, especially the thermal runaway early warning. Developing methods for early failure detection and reducing safety risks from failing high energy lithium-ion batteries has become a major challenge for industry. In this article, a real-time early fault diagnosis scheme for lithium-ion batteries is proposed. By applying both the discrete Fréchet distance and local outlier factor to the voltage and temperature data of the battery cell/module that measured in real time, the battery cell that will have thermal runaway is detected before thermal runaway happens. Compared with the widely used single parameter based diagnosis approach, the proposed one considerably improve the reliability of the fault diagnosis and reduce the false diagnosis rate. The effectiveness of the proposed method is validated with the operational data from electric vehicles with/without thermal runaway in daily use.","Discrete Fréchet distance (DFD); fault diagnosis; lithium-ion battery (LIB); local outlier factor (LOF)","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.","","2023-07-01","","","DC systems, Energy conversion & Storage","","",""
"uuid:aaac9208-ae4d-4d82-8bfb-c04be7b20505","http://resolver.tudelft.nl/uuid:aaac9208-ae4d-4d82-8bfb-c04be7b20505","A virtual experiment for measuring system resilience: a case of chemical process systems","Sun, H. (TU Delft Safety and Security Science; China University of Petroleum (East China)); Yang, M. (TU Delft Safety and Security Science; Universiti Teknologi Malaysia); Wang, Haiqing (China University of Petroleum (East China))","","2022","Resilience is an emergent property of a system, which changes with various internal and external factors. Resilience is also a hidden property of a system that cannot be observed. Thus, experiments should be performed for a given system to measure its resilience. However, physical experiments are practically impossible. Inspired by the tensile test for the stress-strain curve in Material Science, this paper proposes a virtual experiment for measuring system resilience and applies it to a chemical process system. The physical parameters of system resilience of a process system are mapped to those of material resilience. A process system is viewed as a 'specimen' in this experiment. The system performance variation caused by disruptions is seen as the displacement of the specimen caused by the applied load. In absorption phase, the decrease speed of system performance is determined by the failure rate of components under disruptive condition. Response time, including fault diagnosis time and resource allocation time, is used to represent adaptation ability. Restoration ability depends on repair rate of components. For simplicity purpose, the proposed method is applied to resilience assessment of a release prevention barrier system used in the Chevron Richmond refinery crude unit and its associated upstream process.","resilience; process safety; chemical process system; hazardous operation","en","journal article","","","","","","","","","","","Safety and Security Science","","",""
"uuid:36a3fc08-0d3d-4429-bee4-831699c71f7b","http://resolver.tudelft.nl/uuid:36a3fc08-0d3d-4429-bee4-831699c71f7b","Evaluation of the fatigue properties for the long-term service asphalt pavement using the semi-circular bending tests and stereo digital image correlation technique","Cheng, Long (Southeast University); Zhang, Lei (Southeast University); Liu, X. (TU Delft Pavement Engineering); Yuan, Fang (Southeast University); Ma, Yang (Southeast University); Sun, Yinqing (Southeast University)","","2022","Reliable assessment of the fatigue resistance of asphalt pavement with a long-term service is critically crucial for the rational formulation of original pavement utilization strategies in reconstruction and expansion projects. Currently, the pavement performance evaluation indicators are mainly used to guide pavement preventive maintenance, and its applicability in reconstruction and expansion projects of the freeway is limited. This paper aims to propose an evaluation method of fatigue resistance of asphalt concrete utilizing semi-circular bending (SCB) tests and stereo digital image correlation (stereo-DIC) techniques. A total of 27 asphalt concrete cores were drilled from the three freeways (K84, K124, and K165) with a service life of more than 20 years, and the SCB specimens were produced to conduct the SCB fracture and fatigue tests. During the SCB test, the stereo-DIC technique was employed to monitor the evolution process of the strain distribution and crack length for the specimens. K-dimension tree neighbor-searching algorithm (K-d tree algorithm) was used to effectively measure the change of crack length corresponding to each fatigue load cycle. Meanwhile, the strain threshold of asphalt concrete crack initiation was determined by the bilinear softening cohesive zone model (CZM) to ensure the accuracy of the crack length calculated by the K-d tree algorithm. Furthermore, the relationship between crack growth rate and stress intensity, which was used to fit the Paris law parameters, was determined. The CZM and DIC results indicated that the strain threshold of asphalt concrete crack should be set as 2000 με when using the K-d tree algorithm to determine the crack length. With the stress ratio increase, the Paris law parameter A increased wavily, and the parameter n decreased steadily, while the threshold of the stress intensity factor increased steadily. The Paris law master curves could characterize the fatigue performance of various road sections at a wide load range. The residual fatigue life of K84, K124, K165 the road sections were 2.13E + 08, 3.57E + 08, and 1.02E + 07, respectively.","CZM; Fatigue performance; K-d tree algorithm; Paris law; SCB test","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.","","2023-07-01","","","Pavement Engineering","","",""
"uuid:2726cb04-37d4-4f7e-ae4c-4c94990a36b0","http://resolver.tudelft.nl/uuid:2726cb04-37d4-4f7e-ae4c-4c94990a36b0","Neural network model for predicting variation in walking dynamics of pedestrians in social groups","Sun, Shi (Harbin Institute of Technology); Sun, Cheng (Harbin Institute of Technology); Duives, D.C. (TU Delft Transport and Planning); Hoogendoorn, S.P. (TU Delft Transport and Planning)","","2022","Pedestrian spaces are increasingly becoming popular locations for shopping, recreation, festivities, and other social activities. Therefore, an improved understanding of the factors that make walking environments enjoyable and safe is essential. Most existing studies focus on modelling walking behaviours of individual pedestrians. However, most people participate in these activities as parts of social groups. Although the movement and choice behaviours of pedestrians in social groups differ from those of individuals, a model featuring group movements has not been developed. This study uses neural networks to analyse the effects of variables influencing pedestrian movements of social groups and predict the variation in walking dynamics. A top-view video was used to extract the trajectories of pedestrian groups. After identifying the social groups in a crowd, the movement characteristics, pedestrian–environment interaction, inter-pedestrian interaction, intra-group relationship, and inter-group relationship of all group members were calculated and considered in the model. After a variable selection process using neural networks, a neural network model was developed featuring variables that are strongly related to the lateral or longitudinal changes in the individual’s walking speed. The current movement condition, presence of obstacles nearby, impending collisions, current position and velocity of other group members, and following behaviour were found to impact a pedestrian’s walking dynamics. The proposed model can predict the pedestrian density and distribution according to a space function, contributing to better crowd management and efficient design and renovation of pedestrian spaces. Furthermore, the variable selection method can optimise and simplify other pedestrian behaviour prediction models.","Group dynamics; Neural network; Pedestrian; Social group; Unmanned aerial vehicle (UAV)","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.","","2023-07-01","","Transport and Planning","Transport and Planning","","",""
"uuid:67dcf697-9326-4cad-b39a-c3d28ff7e03c","http://resolver.tudelft.nl/uuid:67dcf697-9326-4cad-b39a-c3d28ff7e03c","A STAMP-based approach to quantitative resilience assessment of chemical process systems","Sun, H. (TU Delft Safety and Security Science; China University of Petroleum (East China)); Wang, Haiqing (China University of Petroleum (East China)); Yang, M. (TU Delft Safety and Security Science); Reniers, G.L.L.M.E. (TU Delft Safety and Security Science; Universiteit Antwerpen; Katholieke Universiteit Leuven)","","2022","Chemical process systems (CPSs) involve complex dynamic processes. Besides, the emergent and uncertain hazards and disruptions cannot be identified entirely and prevented by conventional methods. In those situations, resilience for CPSs plays an essential role in absorbing, adapting to disruptions, and restoring from damages. Systemic modeling plays a vital role in assessing resilience. A system-based analysis model, system-theoretic accident model, and process (STAMP) can provide a robust framework. This paper develops a comprehensive methodology to systematically model and assess system resilience. The STAMP is employed to model and analyze the system safety of a process system. A new method of dynamic resilience assessment is then proposed to quantify the resilience of the system. The proposed method is applied to the diesel oil hydrogenation system. The results show that it quantifies the resilience of complex process systems considering human and organizational factors in a dynamic manner.","Chemical process systems; Resilience assessment; STAMP; Systemic","en","journal article","","","","","","","","","","","Safety and Security Science","","",""
"uuid:87463de3-09cb-4c42-8261-a1e500279d38","http://resolver.tudelft.nl/uuid:87463de3-09cb-4c42-8261-a1e500279d38","A mix design methodology of slag and fly ash-based alkali-activated paste","Sun, Beibei (Universiteit Gent); Sun, Yubo (Universiteit Gent); Ye, G. (TU Delft Materials and Environment; Universiteit Gent); De Schutter, Geert (Universiteit Gent)","","2022","In this paper, a series of experiments were conducted to systematically and quantitively explore the effects of control factors on the early age properties, i.e., workability and strength of slag and fly ash-based alkali-activated paste (BFS/FA-AAP). The control factors on the workability (flowability and setting time) of BFS/FA-AAP include the Na2O/b ratio, the SiO2/Na2O ratio, the w/b ratio, and the BFS/b ratio. The control factors on strength (compressive strength and flexural strength) of BFS/FA-AAP further also include the curing condition and the curing age. The results show that a higher BFS/b ratio and Na2O/b ratio could increase the strength while decreasing the workability. A higher w/b ratio could increase the workability while slightly decreasing the strength. Higher SiO2/Na2O ratio increases both strength and workability. Despite that, higher Na2O/b ratio and SiO2/Na2O ratio could hinder the strength development. Sealed curing condition is proved to be a simple but efficient way to assure the steady strength development of BFS/FA-AAP. Although the strength of BFS/FA-AAP could generally stabilize after 90 days, the strength development rate varies with different mix proportions. In addition, a general methodology have been proposed to predict the compressive strength of BFS/FA-AAP and verified with experiments. Finally, a mix design table is proposed for the preliminary design of BFS/FA-AAP according to the principle of satisfying early age requirements.","Control factors; Flowability; Mix design; Setting time; Slag and fly ash-based alkali-activated materials; Strength","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.","","2023-07-01","","","Materials and Environment","","",""
"uuid:0a227967-acee-4725-865c-07cffcb0e821","http://resolver.tudelft.nl/uuid:0a227967-acee-4725-865c-07cffcb0e821","Evaluation of rheology and strength development of alkali-activated slag with different silicates sources","Sun, Yubo (Universiteit Gent); Ghorbani, Saeid (Universiteit Gent); Dai, Xiaodi (Universiteit Gent); Ye, G. (TU Delft Materials and Environment; Universiteit Gent); De Schutter, Geert (Universiteit Gent)","","2022","This study provides a detailed investigation on the reproducibility of two groups of alkali-activated slag (AAS) mixtures, from both fresh properties and strength development perspectives. Three different commercial sodium silicate solutions and one lab-produced silicate activator (made of silica fume and sodium hydroxide) were used to prepare AAS pastes with the same nominal composition in each group. The reaction process of each AAS mixture was monitored by calorimetry and ultrasonic pulse velocity (UPV) measurements. Meanwhile, mini-slump and flow curve tests measured by rheometer were conducted in the first hour to characterize the evolution of fresh properties. The compressive and flexural strength of hardened AAS mortars were measured at different curing ages. The results revealed that AAS pastes prepared with three different sodium silicate solutions exhibited almost identical reaction kinetics, as well as the evolution of fresh properties and strength development. However, the reaction took place rather fast in AAS pastes made of silica fume. These mixtures showed worse rheology and less strength than the corresponding mixtures prepared with sodium silicate solutions. Furthermore, the present study also showed the feasibility of making the same AAS paste through different class commercial sodium silicate solutions.","Alkali-activated slag; Reproducibility; Rheology; Sodium silicate; Strength","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.","","2023-07-01","","","Materials and Environment","","",""
"uuid:f6d09e83-b104-480d-81c9-bae95821d498","http://resolver.tudelft.nl/uuid:f6d09e83-b104-480d-81c9-bae95821d498","Joint energy consumption optimization method for wing-diesel engine-powered hybrid ships towards a more energy-efficient shipping","Wang, Kai (Dalian Maritime University); Xue, Yu (Dalian Maritime University); Xu, Hao (Dalian Maritime University); Huang, Lianzhong (Dalian Maritime University); Ma, Ranqi (Dalian Maritime University); Zhang, Peng (Dalian Maritime University); Jiang, X. (TU Delft Transport Engineering and Logistics); Yuan, Yupeng (University of Cambridge; MOST); Negenborn, R.R. (TU Delft Transport Engineering and Logistics); Sun, Peiting (Dalian Maritime University)","","2022","Wing-diesel engine-powered hybrid ships can effectively reduce fuel consumption and CO2 emissions by using wind energy as the auxiliary driving power. The energy optimization management of the hybrid system can further improve the ship's energy efficiency. To achieve this purpose, it is significant to establish an effective energy consumption model for the energy optimization management of the hybrid system. Therefore, an energy consumption model is established based on the energy conversion analysis of the hybrid power system in this paper. This model can effectively describe the energy consumption of the hybrid ship under different navigational environmental conditions. Then, a joint optimization method of the wing attack angle and of the sailing speed for the hybrid ship is proposed by adopting a swarm intelligence optimization algorithm, in order to reduce energy consumption and CO2 emissions of the hybrid ship under different navigational environmental conditions. Finally, the energy consumption optimization potentials by adopting the hybrid power system and the proposed joint optimization method are analyzed. The results show that the energy consumption and CO2 emissions along a typical route can be reduced by about 4.5%. This study provides an important basis for future practical operations of wing-diesel engine-powered hybrid ships.","Carbon neutrality; Energy consumption optimization; Hybrid ship; Low carbon shipping; Wind energy","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.","","2022-07-29","","","Transport Engineering and Logistics","","",""
"uuid:5ca759b5-7fb8-45f6-8232-dccc0842459f","http://resolver.tudelft.nl/uuid:5ca759b5-7fb8-45f6-8232-dccc0842459f","A review: Reaction mechanism and strength of slag and fly ash-based alkali-activated materials","Sun, Beibei (Universiteit Gent); Ye, G. (TU Delft Materials and Environment); de Schutter, Geert (Universiteit Gent)","","2022","Alkali-activated materials (AAM) are known to be environmentally friendly alternatives to cement-based materials because they can potentially reduce greenhouse gas emissions and reutilize industrial by-products/wastes. To study the factors influencing the strength of slag based alkali-activated materials (BFS-AAM), fly ash based alkali-activated materials (FA-AAM), slag, and fly ash-based alkali-activated materials (BFS/FA-AAM), and clarifying their reaction mechanisms, this paper reviews current knowledge about the mechanical properties and the reaction mechanisms of BFS-AAM, FA-AAM, and BFS/FA-AAM. The precursor requirements and the strength control factors are summarized. The control factors for the strength of BFS/FA-AAM are the BFS/binder ratio, the Na2O/binder ratio, the SiO2/Na2O ratio, and the w/binder ratio. Ion concentrations, determined by these control factors, play a decisive role in the development of strength. Generally, the strength is proportional to the BFS/FA ratio. The optimal values of the Na2O/binder ratio of BFS-AAM and FA-AAM are between 5.5% and 8% and between 7 and 10%, respectively. The optimal values of the SiO2/Na2O ratio of BFS-AAM and FA-AAM are between 0.85 and 1.4 and between 0.6 and 1, respectively. Increasing the w/binder ratio will only benefit workability but will affect the strength negatively. A w/binder ratio of around 0.4 may strike a balance between strength and workability.","Reaction mechanism; Slag and fly ash-based alkali-activated materials; Strength control factors","en","review","","","","","","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","","","Materials and Environment","","",""
"uuid:1b01c624-e944-41a5-9269-82e56a680158","http://resolver.tudelft.nl/uuid:1b01c624-e944-41a5-9269-82e56a680158","Sintering mechanism of Ag nanoparticle-nanoflake: a molecular dynamics simulation","Li, Shizhen (Harbin University of Science and Technology; Southern University of Science and Technology); Liu, Yang (Harbin University of Science and Technology); Ye, H. (Southern University of Science and Technology); Liu, X. (TU Delft Electronic Components, Technology and Materials); Sun, Fenglian (Harbin University of Science and Technology); Fan, Xuejun (Lamar University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2022","This paper studied the behaviors of sintering between Ag nanoparticle (NP) and nanoflake (NF) in the same size by molecular dynamics simulation. Before the sintering simulation, the melting simulation of NF was carried out to calculate the melting points of NFs and investigate the thermostability of NF. The Lindemann index and potential energy showed that the melting points of NF were significantly size-dependent. During the heating process, the sharp corner of NF transformed to the round corner and could bend spontaneously lower than melting points. In sintering simulation, the sintering process of NF-NP showed a metastable stage before equilibrium. Under low sintering temperature (500 K), the degree of plasticity sintering mechanism of NF-NP was more prominent, which generated more defects, such as amorphous atoms, dislocations, and stacking faults, than NP-NP. The sintered products of NF-NP also presented a better neck size and shrinkage than NP-NP in the same size. A new sintering behavior was observed: NF was bent toward the NP during the sintering. The bending curvature of NF increased as the thickness or the length/width decreased. For the NF with the ratio of length/width to thickness of 5:1, bending could further significantly facilitate neck growth. At 700 K, the plasticity mechanism dominated both the sintering processes of NF-NP and NP-NP. And NF-NP showed a larger diffusivity than NP-NP. At last, we investigated the effects of crystal misorientation, and found that a tilted grain boundary generated in the neck. The NF had the trend of rotation to decrease the crystal misorientation.","Melting; Molecular dynamics; Nanoflake; Nanoparticle; Sintering","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:de13d354-9ca5-49c4-a30c-35d50ec19671","http://resolver.tudelft.nl/uuid:de13d354-9ca5-49c4-a30c-35d50ec19671","Rheology of alkali-activated slag pastes: New insight from microstructural investigations by cryo-SEM","Sun, Yubo (Universiteit Gent); Zhang, Shizhe (TU Delft Materials and Environment); Rahul, A. V. (Universiteit Gent); Tao, Yaxin (Universiteit Gent); Van Bockstaele, Filip (Universiteit Gent); Dewettinck, Koen (Universiteit Gent); Ye, G. (TU Delft Materials and Environment; Universiteit Gent); De Schutter, Geert (Universiteit Gent)","","2022","This study aims to interpret the early-stage rheology of alkali-activated slag (AAS) paste from microstructure perspectives. The microstructures visualized by cryogenic scanning electron microscopy (cryo-SEM) revealed the essential distinction between hydroxide and silicate-activated slag pastes. The hydroxide-based mixture showed typical suspension features, where slag particles were dispersed in the hydroxide activators. In the hydroxide media, even at very early ages (5 min), the solid grains were attached to each other through rigid connections of reaction products, which resulted in high yield stress. As for the silicate-based mixtures, an emulsion phase has been observed between slag particles, which consists of discontinuous water droplets and continuous silicate gels. Fine emulsions with smaller water droplets were observed as the silicate modulus of activators increased, which dispersed the slag particles but on the other hand improved the viscosity of the paste. With increasing water to binder ratio, both yield stress and viscosity of AAS pastes significantly reduced.","Alkali-activated materials; Blast furnace slag; Cryo-SEM; Microstructure; Rheology","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.","","2023-07-01","","","Materials and Environment","","",""
"uuid:bde655ee-4d45-45e4-a976-4fc948f67c9a","http://resolver.tudelft.nl/uuid:bde655ee-4d45-45e4-a976-4fc948f67c9a","Resilience-based approach to maintenance asset and operational cost planning","Sun, Hao (China University of Petroleum (East China)); Yang, M. (TU Delft Safety and Security Science); Wang, Haiqing (China University of Petroleum (East China))","","2022","Reliability-based and risk-based methods for directing maintenance activities play a critical role in ensuring system safety and reducing unnecessary downtime. Those methods focus on preventive maintenance to avoid component failures and are applicable before unexpected disruptions occur. However, when disruptions are unavoidable, more attention should be paid to systems’ recovery from unwanted changes. As a remedy of preventive maintenance, improving system restoration capacity of resilience through optimizing the system's maintenance asset and operational cost is an efficient way to help system restore from disruption conditions within an optimal cost. In this paper, a resilience-based approach is proposed to optimize maintenance asset and operational cost. A novel resilience metric is developed and utilized to quantify system resilience under various restoration capacities. The minimal acceptable resilience level (MARL) and maximal acceptable restoration time (MART) are proposed to determine the optimal maintenance cost. The proposed approach is applied to the Chevron Richmond refinery crude unit and its upstream process. The results show that it can help practitioners identify the optimal cost to ensure a system is resilient to respond to uncertain disruptions and provide a dynamic resilience profile to support decision-making.","Cost optimization; Maintenance; Process systems; Resilience; Restoration","en","journal article","","","","","","","","","","","Safety and Security Science","","",""
"uuid:54848940-207b-4fec-a6b6-8fd08c32deeb","http://resolver.tudelft.nl/uuid:54848940-207b-4fec-a6b6-8fd08c32deeb","A parameter identification technique for traffic speed deflectometer tests of pavements","Sun, Z. (TU Delft Pavement Engineering); Kasbergen, C. (TU Delft Pavement Engineering); van Dalen, K.N. (TU Delft Dynamics of Structures); Anupam, K. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology); Erkens, S. (TU Delft Pavement Engineering)","","2022","The structural evaluation of existing pavements forms the basis for formulating cost-effective maintenance and rehabilitation strategies. A promising tool for pavement structural evaluation at network level is the Traffic Speed Deflectometer (TSD) test. However, the application of the TSD test is hindered by the lack of a robust and efficient parameter identification technique. To solve this problem, a theoretical model for the TSD test is first formulated. Then, a minimisation algorithm which works best with the theoretical TSD model for parameter identification is selected. Finally, the performance of this combination in processing field TSD measurements is studied. The results show that the modified Levenberg-Marquardt algorithm using all the 9 detection points is most suitable to be combined with the theoretical TSD model for parameter identification, which gives a promising parameter identification technique for TSD tests of pavements. The presented work contributes to the development of technologies for pavement structural evaluation.","Minimisation algorithm; Moving load; Parameter identification technique; Pavement; Traffic Speed Deflectometer","en","journal article","","","","","","","","","","","Pavement Engineering","","",""
"uuid:5dee7b68-8973-4ab7-a15e-88a78dd01ee6","http://resolver.tudelft.nl/uuid:5dee7b68-8973-4ab7-a15e-88a78dd01ee6","A cooperative strategy for optimizing vehicle relocations and staff movements in cities where several carsharing companies operate simultaneously","Chang, X. (Beijing Jiaotong University); Wu, Jianjun (Beijing Jiaotong University); Correia, Gonçalo (TU Delft Transport and Planning); Sun, Huijun (Beijing Jiaotong University); Feng, Ziyan (Beijing Jiaotong University)","","2022","Carsharing has become a popular travel mode owing to its convenience of use, easy parking, and low cost of using a car by those who only need it occasionally. However, because of the inadequate location of carsharing stations (station-based systems) or vehicles (free-floating systems), effectively requiring expensive and complex relocation strategies, a number of customers are lost, and some carsharing companies are facing bankruptcy. This study proposes a data-driven, dynamic, multi-company relocation method, which aims to reduce relocation costs and increase profit in one-way carsharing station-based systems through cooperative strategies. The method starts from the prediction of carsharing inflows and outflows at each station throughout the day using a new deep learning algorithm designated as “the attention-enhanced temporal graph convolutional network”. It adopts an encoder-decoder structure to simultaneously capture the temporal and spatial carsharing usage patterns. A two-phase integer programming model is proposed to optimize the process of vehicle relocation and staff rebalancing with cooperative relocation strategies: the sharing of relocation staff, the sharing of vehicles and stations among the different companies. An adaptive large neighborhood search based heuristic approach is implemented to solve the two-phase model. Based on the 6-month travel records from four carsharing companies operating simultaneously in Fuzhou, China, the proposed model and cooperative strategies are assessed. The results show that the total profit of the four carsharing companies can be increased by 25.49% with the cooperation of staff and vehicles. In addition, we prospect the future relocation with automated vehicles, whereby the profit can be increased by 46.69% without the need to employ the relocation staff.","Cooperative relocation; Graph convolutional network; Multi-step demand forecasting; One-way carsharing; Staff rebalancing","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.","","2023-07-01","","","Transport and Planning","","",""
"uuid:35c0dcac-5a5d-40ad-8216-231f265353ac","http://resolver.tudelft.nl/uuid:35c0dcac-5a5d-40ad-8216-231f265353ac","A comparison between alkali-activated slag/fly ash binders prepared with natural seawater and deionized water","Ren, Jie (Shenzhen University; University of Colorado); Sun, Hongfang (Shenzhen University); Li, Qun (Shenzhen University); Li, Z. (TU Delft Materials and Environment); Zhang, Xiaogang (Shenzhen University); Wang, Yanshuai (Shenzhen University); Li, Linfei (University of Colorado); Xing, Feng (Shenzhen University)","","2022","In this research, the effects of natural seawater (SW) on the properties of alkali-activated slag/fly ash (AASF) are studied. AASF prepared with deionized water is set as the reference mixture. The results showed that the use of natural SW resulted in a prolonged setting time and lower heat release, but no obvious impact on the flowability of AASF specimens. The long-term compressive strength became higher when SW was used, whereas the corresponding flexural strength and fractural toughness turned lower. The use of SW induced the formation of new products that were not identified in the reference mixture, such as Cl–hydrocalumite and gypsum. In addition, it is evidenced that the dissolution of fly ash (FA) particles was significantly delayed with the incorporation of SW. All these results were related to the various ions introduced by the natural SW and their interactions with the alkaline activator as well as the precipitation of salts on slag and FA surfaces or in the matrix.","alkali-activated slag/fly ash; hydration kinetics; mechanical properties; microstructure; seawater; setting time","en","journal article","","","","","","","","","","","Materials and Environment","","",""
"uuid:eba3927a-a0bd-41e5-aa5f-ecfdd52f5109","http://resolver.tudelft.nl/uuid:eba3927a-a0bd-41e5-aa5f-ecfdd52f5109","A new installation technology of large diameter deeply-buried caissons: Practical application and observed performance","Lai, F. (TU Delft Geo-engineering; Southeast University); Liu, Songyu (Southeast University); Li, Yaoliang (Shanghai Foundation Engineering Group Co.); Sun, Yanxiao (Southeast University)","","2022","The development of installation technologies of open caissons has been lagging behind increasingly complex construction conditions. For such purpose, a new installation technology of large diameter deeply-buried (LDDB) open caissons has been developed and then used for construction of twin LDDB caissons into undrained ground with stiff soils in Zhenjiang, China. To assess the installation effects and filed performance, a monitoring program was presented to document the variations in total jacking forces provided by new shaft driven method, ground water level (GWL) around the caisson shaft, inclination angles of caisson shafts and radial displacements of surrounding soils as well as surface settlements of existing nearby facilities. It is observed that the monitoring data during the installation falls almost entirely within the design criteria, the reported new technology has limited impacts on the induced ground movements, depending on the variation in GWL, interaction between twin caissons and excavation-induced unloading effect. Moreover, the total jacking forces increase approximately in stepwise shape as the installation depth increases; the change law of surface settlements is highly similar to those of GWL, showing their close correlation; the larger inclination angles of caisson shafts are mainly encountered in the earlier installation phase, but well controllable. Further discussion on ground movements caused by various technologies confirms the feasibility of new installation technology. Both the observed and compared results give greater confidence on the use of such the technology in practice.","Construction technology; Field observation; Installation effect; Interaction; Large diameter deeply-buried caisson","en","journal article","","","","","","","","","","","Geo-engineering","","",""
"uuid:25778bc8-37e1-4d3c-89db-ee30f1f414da","http://resolver.tudelft.nl/uuid:25778bc8-37e1-4d3c-89db-ee30f1f414da","Risk assessment methods of cascade reservoir dams: a review and reflection","Wang, Te (Zhengzhou University); Li, Zongkun (Zhengzhou University); Ge, W. (TU Delft Safety and Security Science; Zhengzhou University); Zhang, Yadong (Zhengzhou University); Jiao, Yutie (Zhengzhou University); Zhang, Hua (Zhengzhou University); Sun, Heqiang (Zhengzhou University); van Gelder, P.H.A.J.M. (TU Delft Safety and Security Science)","","2022","Risk assessment of cascade reservoir dams is not only the key to ensure the safety of the basin, but also the objective requirement of dam risk management. Based on the development status of cascade reservoirs in China, the complexity of dam risk management of cascade reservoirs compared with a single reservoir was analyzed. By reviewing the advances on the studies of dam risk in cascade reservoirs, this paper summarized their limitations in terms of scientificity and practicability. Moreover, some concepts and methods were proposed on the risk assessment of cascade reservoirs: (1) The dam risk of a cascade reservoir was decomposed into own risk and additional risk, the consequence of its dam breach was decomposed into direct loss and potential loss, and an influence coefficient was defined to reflect the risk transmission and superposition degree among cascade reservoirs; (2) The related concepts and formulas for the calculation of dam risk probability and consequence of cascade reservoirs were proposed, which realized the transition of dam risk assessment method from a single reservoir to cascade reservoirs; (3) A project rank classification method for cascade reservoirs was proposed, which took into account not only the project scale and benefits in socioeconomic development, but also the successive dam breaches possibility and consequences. This study is of great significance to clarify the focus of future research and promote the practical application of dam risk management in cascade reservoirs.","Cascade reservoirs; Dam breach; Probability; Risk assessment; Risk transmission","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.","","2023-07-01","","","Safety and Security Science","","",""
"uuid:679aca4d-8276-4480-ace5-4a1736cbd8fd","http://resolver.tudelft.nl/uuid:679aca4d-8276-4480-ace5-4a1736cbd8fd","Artificial intelligence powered large-scale renewable integrations in multi-energy systems for carbon neutrality transition: Challenges and future perspectives","Liu, Zhengxuan (TU Delft Design & Construction Management; Hunan University); Sun, Ying (Concordia University); Xing, Chaojie (Hunan University); Liu, Jia (Guangzhou University; The Hong Kong Polytechnic University); He, Yingdong (Hunan University); Zhou, Yuekuan (The Hong Kong University of Science and Technology; HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute); Zhang, Guoqiang (Hunan University)","","2022","The vigorous expansion of renewable energy as a substitute for fossil energy is the predominant route of action to achieve worldwide carbon neutrality. However, clean energy supplies in multi-energy building districts are still at the preliminary stages for energy paradigm transitions. In particular, technologies and methodologies for large-scale renewable energy integrations are still not sufficiently sophisticated, in terms of intelligent control management. Artificial intelligent (AI) techniques powered renewable energy systems can learn from bio-inspired lessons and provide power systems with intelligence. However, there are few in-depth dissections and deliberations on the roles of AI techniques for large-scale integrations of renewable energy and decarbonisation in multi-energy systems. This study summarizes the commonly used AI-related approaches and discusses their functional advantages when being applied in various renewable energy sectors, as well as their functional contribution to optimizing the operational control modalities of renewable energy and improving the overall operational effectiveness. This study also presents practical applications of various AI techniques in large-scale renewable energy integration systems, and analyzes their effectiveness through theoretical explanations and diverse case studies. In addition, this study introduces limitations and challenges associated with the large-scale renewable energy integrations for carbon neutrality transition using relevant AI techniques, and proposes further promising research perspectives and recommendations. This comprehensive review ignites advanced AI techniques for large-scale renewable integrations and provides valuable informational instructions and guidelines to different stakeholders (e.g., engineers, designers and scientists) for carbon neutrality transition.","Artificial intelligent techniques; Carbon neutrality; Energy transition; Large-scale integration; Renewable energy","en","review","","","","","","","","","","","Design & Construction Management","","",""
"uuid:6e7f9017-3fb6-4779-adea-0d0c62fb3019","http://resolver.tudelft.nl/uuid:6e7f9017-3fb6-4779-adea-0d0c62fb3019","Revisiting Bundle Recommendation: Datasets, Tasks, Challenges and Opportunities for Intent-aware Product Bundling","Sun, Zhu (Institute of High Performance Computing); Yang, J. (TU Delft Web Information Systems); Feng, Kaidong (Yanshan University); Fang, Hui (Shanghai University of Finance and Economics); Qu, Xinghua (Bytedance AI Lab); Ong, Yew Soon (Nanyang Technological University)","","2022","Product bundling is a commonly-used marketing strategy in both offline retailers and online e-commerce systems. Current research on bundle recommendation is limited by: (1) noisy datasets, where bundles are defined by heuristics, e.g., products co-purchased in the same session; and (2) specific tasks, holding unrealistic assumptions, e.g., the availability of bundles for recommendation directly. In this paper, we propose to take a step back and consider the process of bundle recommendation from a holistic user experience perspective. We first construct high-quality bundle datasets with rich meta information, particularly bundle intents, through a carefully designed crowd-sourcing task. We then define a series of tasks that together, support all key steps in a typical bundle recommendation process, from bundle detection, completion, ranking, to explanation and auto-naming. Finally, we conduct extensive experiments and in-depth analysis that demonstrate the challenges of bundle recommendation, arising from the need for capturing complex relations among users, products, and bundles, as well as the research opportunities, especially in graph-based neural methods. To sum up, our study delivers new data sources, opens up new research directions, and provides useful guidance for product bundling in real e-commerce platforms. Our datasets are available at GitHub (\urlhttps: //github.com/BundleRec/bundle_recommendation ).","bundle completion; bundle detection; bundle ranking; crowd-sourcing; product bundling; user intents","en","conference paper","Association for Computing Machinery (ACM)","","","","","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","","","Web Information Systems","","",""
"uuid:dfbc01d2-7279-4b9e-a3e9-54d840ee1511","http://resolver.tudelft.nl/uuid:dfbc01d2-7279-4b9e-a3e9-54d840ee1511","Fresh and hardened properties of alkali-activated slag concrete: The effect of fly ash as a supplementary precursor","Sun, Yubo (Universiteit Gent); Liu, Zhiyuan (Universiteit Gent); Ghorbani, Saeid (Universiteit Gent); Ye, G. (TU Delft Materials and Environment; Universiteit Gent); De Schutter, Geert (Universiteit Gent)","","2022","The present study explores the possibility of replacing blast furnace slag (BFS) with coal fly ash (FA) to produce alkali-activated material (AAM) concrete with hybrid precursors. With an increased FA replacement ratio, the reaction kinetics, fresh and hardened properties of AAM mixtures have been investigated. The retardation effect on the reaction kinetics with an increased FA content has been observed, which not only extended the induction period along with the heat flow evolution but also reduced the cumulative heat release up to 24 h. Spherical FA particles can provide a ball-bearing effect to improve the workability of the hybrid AAM mixtures, while FA also slows down the deterioration of fresh properties since they are less reactive compared to BFS particles. Regarding the strength development, FA results in the reduction at all curing ages in the mixtures with a low silicate modulus (Ms0.25). Similarly, reduction in 1-day compressive strength has been detected in high silicate modulus mixtures (Ms0.5) with FA replacement, while the mixture with 10% FA exhibits the highest compressive strength among Ms0.5 concretes at later curing ages. Bigger capillary pores have been detected in AAM mixtures with an increase in FA content. However, AAM with 10% FA shows the lowest porosity in Ms0.5 mixtures, which is in agreement with the compressive strength results.","Alkali-activated material concrete; Blast furnace slag; Coal fly ash; Rheology; Strength development","en","journal article","","","","","","","","","","","Materials and Environment","","",""
"uuid:a6fec65d-b5ff-4a56-adca-431b4af37adb","http://resolver.tudelft.nl/uuid:a6fec65d-b5ff-4a56-adca-431b4af37adb","DEM-based stress transmission in asphalt mixture skeleton filling system","Xing, Chao (Harbin Institute of Technology); Liu, Bo (Harbin Institute of Technology); Sun, Zhiqi (Shijiazhuang Tiedao University); Tan, Yiqiu (Harbin Institute of Technology); Liu, X. (TU Delft Pavement Engineering); Zhou, Changhong (Guilin University of Electronic Technology)","","2022","Asphalt mixture is a skeleton filling system consisting of aggregate, asphalt, and mineral powder. High performance asphalt mixture design is directly affected by internal stress transmission of skeleton filling system. In this paper, the discrete element method based on digital image was employed to study the stress transmission. By analyzing the effect of skeleton structure on the contact force between aggregate and mortar, it is concluded that the skeleton aggregate in the asphalt mixture is the main stress transmission medium. The lower the degree of disruption, the higher the contact force of skeleton aggregate. At the same time, the variation coefficient of contact force of asphalt mortar with low filling coefficient is larger and the localization phenomenon is more serious. By analyzing the effect of mortar properties on the contact force between aggregate and mortar, it is concluded that the lower the modulus of asphalt mortar, the higher the degree of localization of contact force and the more likely to have local damage.","Asphalt mixtures; Contact force transmission; DEM; Mesostructure; Skeleton filling system","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.","","2023-07-01","","","Pavement Engineering","","",""
"uuid:150085fa-18cd-4e2b-ad0a-202312530a83","http://resolver.tudelft.nl/uuid:150085fa-18cd-4e2b-ad0a-202312530a83","Conductive Co-based metal organic framework nanostructures for excellent potassium- and lithium-ion storage: Kinetics and mechanism studies","Mao, Pengcheng (Northeastern University); Fan, Huilin (Northeastern University); Liu, Chang (Northeastern University); Lan, Gongxu (Northeastern University); Huang, Wei (Hunan Agricultural University); Li, Zhipeng (University of Science and Technology Beijing); Amin Hassan, H.M. (TU Delft EKL Equipment; Zagazig University); Zheng, Runguo (Northeastern University); Wang, Zhiyuan (Northeastern University); Sun, Hongyu (Northeastern University); Liu, Yanguo (Northeastern University)","","2022","Thanks to the low cost and earth's abundant potassium resources, potassium ion batteries (PIBs) have attracted much interest as alternative energy storage devices. However, there is still a great challenge to develop suitable anode materials for PIBs with high specific capacity, fast charge/discharge and stable ion storage. Nowadays, conductive metal-organic frameworks (c-MOFs) with excellent physicochemical properties are employed for different electrochemical applications, but the study of their potassium storage performance remains unknown, and the detailed potassium storage mechanism needs to be explored. Herein, nanostructured Co3(HHTP)2 c-MOF (Co-CAT MOF, HHTP: 2,3,6,7,10,11-hexahydroxytriphenylene) is synthesized by a liquid-phase method and evaluated as the anode for PIBs. The active sites and open pathways in the conductive Co-CAT MOF promote ion diffusion and electron transfer, exhibiting high reversible specific capacity (332 mA h g−1 at 0.1 A g−1), excellent long-cycle stability (230 mA h g−1 at the current density of 1.0 A g−1 after 700 cycles) and outstanding rate performance (165 mA h g−1 at 4.0 A g−1), which is superior to the typical PIB anodes. Combined with different ex situ characterization techniques, the potassium storage mechanism based on 8-electron transfer is revealed. Furthermore, Co-CAT MOF exhibits excellent Li-ion storage performance. In the half-cell, the Co-CAT MOF electrode displays a high reversible capacity of 800 mA h g−1 at 200 mA g−1. In addition, the Co-CAT//LiCoO2 full cell cycles for 100 cycles at 200 mA h g−1. It is believed that Co-CAT MOF is a promising electrode material for potassium/lithium storage, and the proposed ion storage mechanism can be used to discover other MOF-based electrodes for energy storage.","","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.","","2023-07-01","","","EKL Equipment","","",""
"uuid:3cf28e84-0f7e-463b-b421-980987d210d4","http://resolver.tudelft.nl/uuid:3cf28e84-0f7e-463b-b421-980987d210d4","On the Estimation of Vector Wind Profiles Using Aircraft-Derived Data and Gaussian Process Regression","Marinescu, Marius (Universidad Rey Juan Carlos); Olivares, Alberto (Universidad Rey Juan Carlos); Staffetti, Ernesto (Universidad Rey Juan Carlos); Sun, Junzi (TU Delft Control & Simulation)","","2022","This work addresses the problem of vertical wind profile online estimation at a given location. Specifically, the north and east components of the wind are continuously estimated as functions of time and altitude at two waypoints used for landing on the Adolfo Suarez Madrid-Barajas airport. A continuous nowcast of the wind profile is performed in which wind observations are derived from the aircraft states and assimilated into the model. It is well known that wind is one of the utmost contributors to uncertainties in the current and future paradigm of Air Traffic Management. Accurate wind information is key in continuous climb and descent operations, spacing, four dimensional trajectory-based operations, and aircraft performance studies, among others. In this work, wind data are obtained indirectly from the aircraft’s states broadcast by the Mode S and ADS-B aircraft surveillance systems. The Gaussian process regression is adapted to this framework and used to solve the problem. The presented method allows to construct a complete vector wind profile at any specific position that is continuous in time and altitude; namely, there is no need for grid points and time discretisation. The Gaussian process regression is a very flexible estimator which is statistically consistent under general conditions, meaning that it converges to the underground truth when more and more data are dispensed. In addition, the Gaussian process regression approach provides the whole probability distribution of any particular estimation, allowing confidence intervals to be computed naturally. In the case study presented in this paper, in which the wind is constantly estimated, the Gaussian process regression model is iteratively updated every 15 min to capture possible changes in the wind behaviour and give an estimation of the wind profile every half a minute. The method has been validated using a test dataset, achieving a reduction of 50% of the prediction uncertainty in comparison to a baseline model. Moreover, two popular wind profile estimators based on the Kalman filter are also implemented for the sake of comparison. The Kalman filter outperforms the baseline model, but it does not outperform the Gaussian process regression with errors higher by around 35%, in comparison. The obtained results show that the Gaussian process regression of aircraft-derived data reliably nowcast the wind state, which is key in Air Traffic Management.","ADS-B; Air Traffic Management; Gaussian process regression; Kalman filter; Mode S; wind estimation","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:4f3e3b25-ce23-47b3-86a9-5523be3daa1a","http://resolver.tudelft.nl/uuid:4f3e3b25-ce23-47b3-86a9-5523be3daa1a","Carbonation Behavior of Engineered Cementitious Composites under Coupled Sustained Flexural Load and Accelerated Carbonation","Zhang, Hongzhi (Shandong University); Shao, Yingxuan (Shandong University); Zhang, Ning (Shandong Hi-Speed Engineering Test CO); Tawfek, Abdullah M. (Shandong University; Sana'a University); Guan, Yanhua (Shandong University); Sun, Renjuan (Shandong University); Tian, Changjin (Shandong University); Šavija, B. (TU Delft Materials and Environment)","","2022","Engineered cementitious composites (ECCs) belong to a broad class of fibre-reinforced concrete. They incorporate synthetic polyvinyl alcohol (PVA) fibres, cement, fly ash and fine aggregates, and are designed to have a tensile strain capacity typically beyond 3%. This paper presents an investigation on the carbonation behaviour of engineered cementitious composites (ECCs) under coupled sustained flexural load and accelerated carbonation. The carbonation depth under a sustained stress level of 0, 0.075, 0.15, 0.3 and 0.6 relative to flexural strength was measured after 7, 14 and 28 days of accelerated carbonation. Thermogravimetric analysis, mercury intrusion porosimetry and microhardness measurements were carried out to show the coupled influence of sustained flexural load and accelerated carbonation on the changes of the mineral phases, porosity, pore size distribution and microhardness along the carbonation profile. A modified carbonation depth model that can be used to consider the coupled effect of flexural tensile stress and carbonation time was proposed. The results show that an exponential relationship can be observed between stress influence coefficient and flexural tensile stress level in the carbonation depth model of ECC, which is different when using plain concrete. Areas with a higher carbonation degree have greater microhardness, even under a large sustained load level, as the carbonation process refines the pore structure and the fibre bridges the crack effectively.","accelerated carbonation; engineered cementitious composites; microhardness; microstructure; sustained flexural load","en","journal article","","","","","","","","","","","Materials and Environment","","",""
"uuid:80ad5e99-66c6-4b1d-9dda-6df3d050750a","http://resolver.tudelft.nl/uuid:80ad5e99-66c6-4b1d-9dda-6df3d050750a","Dynamic Risk Assessment of Chemical Process Systems using System-Theoretic Accident Model and Process (STAMP) and Failure Propagation Model","Sun, H. (TU Delft Safety and Security Science; China University of Petroleum (East China)); Wang, Haiqing (China University of Petroleum (East China)); Yang, M. (TU Delft Safety and Security Science); Reniers, G.L.L.M.E. (TU Delft Safety and Security Science; Universiteit Antwerpen; Katholieke Universiteit Leuven)","","2022","Chemical process systems involve complex dynamic processes, and the state of the system often fluctuates during the production process. To ensure the continuation of production, these fluctuations are often ignored or processed online instead of shutting down the unit. However, the interdependence between components in the system is strong, and small fluctuations or faults will be propagated to downstream nodes in turn if the fluctuation is omitted or processed online. A large number of accident investigations prove that the system risk increments as the failure propagates. This may eventually cause the entire system to collapse, causing severe casualties, property losses, and environmental damage. However, little attention has been paid to this type of risk. To measure the dynamic risk profile considering the fluctuation of the production process, this paper proposes a new risk assessment model that integrates the system-theoretic accident model and process (STAMP) and the failure propagation model. Firstly, the STAMP is used to model and analyze the system safety of a process system. An approach is then developed to quantify the risk accumulation of the model based on the failure propagation model. The process of the Chevron Richmond refinery crude unit and its associated upstream process is used to demonstrate the application of the proposed approach.","","en","journal article","","","","","","","","","","","Safety and Security Science","","",""
"uuid:8d5c7f02-c24f-4283-bded-c986d61cf061","http://resolver.tudelft.nl/uuid:8d5c7f02-c24f-4283-bded-c986d61cf061","Compound flood impact of water level and rainfall during tropical cyclone periods in a coastal city: the case of Shanghai","Xu, H. (TU Delft Hydraulic Structures and Flood Risk; Southern University of Science and Technology; East China Normal University); Tian, Zhan (Southern University of Science and Technology; Pengcheng Laboratory, Shenzhen); Sun, Laixiang (SOAS University of London; University of Maryland); Ye, Qinghua (TU Delft Coastal Engineering; Deltares); Ragno, E. (TU Delft Hydraulic Structures and Flood Risk); Bricker, J.D. (TU Delft Hydraulic Structures and Flood Risk; University of Michigan); Tan, Jinkai (Sun Yat-sen University); Ke, Q. (TU Delft Hydraulic Structures and Flood Risk); Wang, Shuai (Imperial College London)","","2022","Compound flooding is generated when two or more flood drivers occur simultaneously or in close succession. Multiple drivers can amplify each other and lead to greater impacts than when they occur in isolation. A better understanding of the interdependence between flood drivers would facilitate a more accurate assessment of compound flood risk in coastal regions. This study employed the D-Flow Flexible Mesh model to simulate the historical peak coastal water level, consisting of the storm surge, astronomical tide, and relative sea level rise (RSLR), in Shanghai over the period 1961-2018. It then applies a copula-based methodology to calculate the joint probability of peak water level and rainfall during historical tropical cyclones (TCs) and to calculate the marginal contribution of each driver. The results indicate that the astronomical tide is the leading driver of peak water level, followed by the contribution of the storm surge. In the longer term, the RSLR has significantly amplified the peak water level. This study investigates the dependency of compound flood events in Shanghai on multiple drivers, which helps us to better understand compound floods and provides scientific references for flood risk management and for further studies. The framework developed in this study could be applied to other coastal cities that face the same constraint of unavailable water level records.","","en","journal article","","","","","","","","","","","Hydraulic Structures and Flood Risk","","",""
"uuid:7598bc23-968c-4184-bcac-9d84288e9f51","http://resolver.tudelft.nl/uuid:7598bc23-968c-4184-bcac-9d84288e9f51","Statistical mixture design for carbide residue activated blast furnace slag foamed lightweight concrete","Zhang, Hongzhi (Shandong University); He, Yanchen (Shandong University); Wang, Chuan (Shandong Hi-speed Group); Guan, Yanhua (Shandong University); Ge, Zhi (Shandong University); Sun, Renjuan (Shandong University); Ling, Yifeng (Shandong University); Šavija, B. (TU Delft Materials and Environment)","","2022","Carbide residue activated blast furnace slag is a relatively new kind of eco-friendly construction materials. This work addresses the design of foamed lightweight concrete as road embankment material using such material. A statistical mixture design approach was adopted to assess the influence of each ingredient as well as the interaction between these on the spreadability and compressive strength and thus allowing mixture design. The fitted models were validated using analysis of variance, residual analysis and confirmed by the experiments. Afterwards, the proposed models were used to optimize the mixture. The mixture with the highest compressive strength and the maximum content of carbide residue that allows the mixture to meet the required properties were obtained, respectively.","Blast furnace slag; Carbide residue; Foamed lightweight concrete; Statistical mixture design","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.","","2023-07-01","","","Materials and Environment","","",""
"uuid:e939b815-6f5b-4f18-ba29-f8f5d7d7592d","http://resolver.tudelft.nl/uuid:e939b815-6f5b-4f18-ba29-f8f5d7d7592d","A Biocatalytic Platform for the Synthesis of Enantiopure Propargylic Alcohols and Amines","Sang, Xianke (Chinese Academy of Sciences); Tong, Feifei (Chinese Academy of Sciences); Zeng, Zhigang (Hubei University of Science and Technology, Hubei); Wu, Minghu (Hubei University of Science and Technology, Hubei); Yuan, Bo (Chinese Academy of Sciences); Sun, Zhoutong (Chinese Academy of Sciences); Sheng, Xiang (Chinese Academy of Sciences); Hollmann, F. (TU Delft BT/Biocatalysis); Zhang, W. (TU Delft BT/Biocatalysis; Chinese Academy of Sciences)","","2022","Propargylic alcohols and amines are versatile building blocks in organic synthesis. We demonstrate a straightforward enzymatic cascade to synthesize enantiomerically pure propargylic alcohols and amines from readily available racemic starting materials. In the first step, the peroxygenase from Agrocybe aegerita converted the racemic propargylic alcohols into the corresponding ketones, which then were converted into the enantiomerically pure alcohols using the (R)-selective alcohol dehydrogenase from Lactobacillus kefir or the (S)-selective alcohol dehydrogenase from Thermoanaerobacter brokii. Moreover, an enzymatic Mitsunobu-type conversion of the racemic alcohols into enantiomerically enriched propargylic amines using (R)-selective amine transaminase from Aspergillus terreus or (S)-selective amine transaminase from Chromobacterium violaceum was established. The one-pot two-step cascade reaction yielded a broad range of enantioenriched alcohol and amine products in 70-99% yield.","","en","journal article","","","","","","","","","","","BT/Biocatalysis","","",""
"uuid:ded518a4-3538-4f0a-9a59-8e598bbc578e","http://resolver.tudelft.nl/uuid:ded518a4-3538-4f0a-9a59-8e598bbc578e","Automatic depression recognition by intelligent speech signal processing: A systematic survey","Wu, Pingping (Nanjing Audit University); Wang, Ruihao (Nanjing Audit University); Lin, Han (Nanjing Audit University); Zhang, Fanlong (Nanjing Audit University); Tu, Juan (Nanjing University); Sun, M. (TU Delft Signal Processing Systems)","","2022","Depression has become one of the most common mental illnesses in the world. For better prediction and diagnosis, methods of automatic depression recognition based on speech signal are constantly proposed and updated, with a transition from the early traditional methods based on hand-crafted features to the application of architectures of deep learning. This paper systematically and precisely outlines the most prominent and up-to-date research of automatic depression recognition by intelligent speech signal processing so far. Furthermore, methods for acoustic feature extraction, algorithms for classification and regression, as well as end to end deep models are investigated and analysed. Finally, general trends are summarised and key unresolved issues are identified to be considered in future studies of automatic speech depression recognition.","","en","review","","","","","","","","","","","Signal Processing Systems","","",""
"uuid:1dd5ea51-a12d-4672-a172-c727f94c80e1","http://resolver.tudelft.nl/uuid:1dd5ea51-a12d-4672-a172-c727f94c80e1","Template-free preparation of porous Co microfibers from spent lithium-ion batteries as a promising microwave absorber","Wu, Xiao Min (Anhui University of Technology); Xie, Fei (Anhui University of Technology); Yao, Yong Lin (Anhui University of Technology); Sun, Yue (Anhui University of Technology); Hua, Zhong Sheng (Anhui University of Technology); Zhao, Zhuo (Anhui University of Technology); Yang, Y. (TU Delft Team Yongxiang Yang)","","2022","In order to take full advantage of the secondary resources, in this paper, we reported a template-free process to prepare porous Co microfibers from spent lithium-ion batteries (LIBs). First, the waste LiCoO2 powders were leached by oxalic acid at a suitable temperature, and rod-like cobalt oxalate powders were obtained. Second, the porous Co microfibers were prepared by using the cobalt oxalate as precursors through a thermal decomposition at 420 °C under nitrogen atmosphere. The prepared Co microfibers possess diameters of 1–2 μm, and each microfiber consists of small particles with size of 100–200 nm. The Co microfibers (25 wt%)/paraffin composite exhibited excellent microwave absorption performance. When the sample thickness is 4.5 mm, the reflection losses reach − 36.14 and − 38.20 dB at 4.16 and 17.60 GHz, respectively, and the effective bandwidth reaches up to 5.52 GHz. This indicates that the Co microfibers can be used as a promising microwave absorber. Therefore, this paper demonstrates a novel process to make a high value-added product through recycling from the spent lithium-ion batteries. In addition, it is advantageous to eliminate the hazard of spent lithium-ion batteries and electromagnetic radiation to environment and human health. Graphical abstract: [Figure not available: see fulltext.].","Co microfibers; Microwave absorption; Oxalic acid leaching; Recycling; Spent lithium-ion batteries (LIBs)","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.","","2023-07-01","","","Team Yongxiang Yang","","",""
"uuid:dcb59004-36a2-48ee-8b87-0e64822773c4","http://resolver.tudelft.nl/uuid:dcb59004-36a2-48ee-8b87-0e64822773c4","Random forest incorporating ab-initio calculations for corrosion rate prediction with small sample Al alloys data","Ji, Y. (TU Delft Materials Science and Engineering; University of Science and Technology Beijing); Li, Ni (University of Science and Technology Beijing); Cheng, Zhanming (University of Science and Technology Beijing); Fu, Xiaoqian (University of Science and Technology Beijing); Sun, Xiaoguang (CRRC Qingdao Sifang Co. Ltd); Chowwanonthapunya, Thee (Kasetsart University); Zhang, Dawei (University of Science and Technology Beijing); Ren, Jingli (Zhengzhou University); Dey, P. (TU Delft Team Poulumi Dey); Dong, Chaofang (University of Science and Technology Beijing)","","2022","Corrosion jeopardizes the materials longevity and engineering safety, hence the corrosion rate needs to be forecasted so as to better guide materials selection. Although field exposure experiments are dependable, the prohibitive cost and their time-consuming nature make it difficult to obtain large dataset for machine learning. Here, we propose a strategy Integrating Ab-initio Calculations with Random Forest (IACRF) to optimize the model, thereby estimating the corrosion rate of Al alloys in diverse environments. Based on the thermodynamic assessment of the secondary phases, the ab-initio calculation quantities, especially the work function, significantly improved the prediction accuracy with respect to small-sample Al alloys corrosion dataset. To build a better generic prediction model, the most accessible and effective features are identified to train IACRF. Finally, the independent field exposure experiments in Southeast Asia have proven the generalization ability of IACRF in which the average prediction accuracy is improved up to 91%.","","en","journal article","","","","","","","","","","Materials Science and Engineering","Team Poulumi Dey","","",""
"uuid:667d438c-de8e-411b-84b6-7d9102118bb6","http://resolver.tudelft.nl/uuid:667d438c-de8e-411b-84b6-7d9102118bb6","Electrical characteristics and photodetection mechanism of TiO2/AlGaN/GaN heterostructure-based ultraviolet detectors with a Schottky junction","Zhan, Teng (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Sun, J. (TU Delft Electronic Components, Technology and Materials; Tsinghua University); Feng, Tao (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Zhang, Yulong (Tsinghua University); Zhou, Binru (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Zhang, Banghong (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Wang, Junxi (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Sarro, Pasqualina M (TU Delft Electronic Components, Technology and Materials); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2022","Recent research focusing on wide-bandgap and two-dimensional materials with a Schottky junction has provided a new concept for ultraviolet photodetectors. However, the working mechanism of the Schottky junction-based detector varies depending on the photosensitive materials used and the device structure. We demonstrated a TiO2/AlGaN/GaN heterostructure-based photodetector with a Schottky junction, integrating an ultraviolet photosensitive TiO2 nanolayer, a two-dimensional electron gas (2DEG) field effect transistor, and a metal-semiconductor Schottky diode. The spectral response wavelength region of the detector is 200-365 nm and the peak responsivity is 37.396 A W−1 at −5 V bias under 240 nm UV illumination, respectively. Meanwhile, a peak photo-to-dark current ratio (PDCR) of 5.1 × 102 at −2 V bias voltage was observed under 274 nm UV irradiation. This Schottky-based 2DEG heterostructure detector can realize three dominant working principles: (i) the Schottky emission mechanism at a low reverse voltage (0-1 V) before the current is fully turned on, (ii) the Poole-Frenkel emission mechanism at a medium reverse voltage (−1 to −2 V) with peak PDCR, and (iii) the Fowler-Nordheim tunneling mechanism at a high reverse voltage (>−2 V) with a high responsivity. Continuous cycle response measurement results indicate that the detectors have good response repeatability and reliability. The characteristics of response wavelength, responsivity, and stability show that the detector can be used for several commercial applications, including sunscreen UV monitoring and LED sterilization light source detection.","","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. Correction: https://doi.org/10.1039/D2TC04491A","","2023-06-19","","","Electronic Components, Technology and Materials","","",""
"uuid:806ab43b-61bf-4838-bb06-596e5ef71468","http://resolver.tudelft.nl/uuid:806ab43b-61bf-4838-bb06-596e5ef71468","Thickness-Independent Capacitive Performance of Holey Ti3C2Tx Film Prepared through a Mild Oxidation Strategy","Guo, R. (TU Delft RST/Storage of Electrochemical Energy; Shaanxi Normal University); Yuan, Peng (Shaanxi Normal University); Han, Xiying (Shaanxi Normal University); He, Xuexia (Shaanxi Normal University); Lu, Jiangbo (Shaanxi Normal University); Li, Qi (Shaanxi Normal University); Dang, Liqin (Shaanxi Normal University); Sun, Jie (Shaanxi Normal University); Liu, Zonghuai (Shaanxi Normal University); Lei, Zhibin (Shaanxi Normal University)","","2022","The Ti3C2Tx film with metallic conductivity and high pseudo-capacitance holds profound promise in flexible high-rate supercapacitors. However, the restacking of Ti3C2Tx sheets hinders ion access to thick film electrodes. Herein, a mild yet green route has been developed to partially oxidize Ti3C2Tx to TiO2/Ti3C2Tx by introducing O2 molecules during refluxing the Ti3C2Tx suspension. The subsequent etching away of these TiO2 nanoparticles by HF leaves behind numerous in-plane nanopores on the Ti3C2Tx sheets. Electrochemical impedance spectroscopy shows that longer oxidation time of 40 min yields holey Ti3C2Tx (H-Ti3C2Tx) with a much shorter relax time constant of 0.85 s at electrode thickness of 25 µm, which is 89 times smaller than that of the pristineTi3C2Tx film (75.58 s). Meanwhile, H-Ti3C2Tx film with 25 min oxidation exhibits less-dependent capacitive performance in film thickness range of 10–84 µm (1.63–6.41 mg cm−2) and maintains around 60% capacitance as the current density increases from 1 to 50 A g−1. The findings clearly demonstrate that in-plane nanopores not only provide more electrochemically active sites, but also offer numerous pathways for rapid ion impregnation across the thick Ti3C2Tx film. The method reported herein would pave way for fabricating porous MXene materials toward high-rate flexible supercapacitor applications.","capacitive performances; controllable oxidation; holey Ti C T; supercapacitors; thick film electrodes","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.","","2023-07-01","","","RST/Storage of Electrochemical Energy","","",""
"uuid:b85c76b7-8e14-45b2-82ca-beb41c51a708","http://resolver.tudelft.nl/uuid:b85c76b7-8e14-45b2-82ca-beb41c51a708","Effect of High-Range Water-Reducing Admixtures on Alkali-Activated Slag Concrete","Sun, Yubo (Universiteit Gent); Tao, Yaxin (Universiteit Gent); Rahul, A. V. (Universiteit Gent); Ye, G. (TU Delft Materials and Environment; Universiteit Gent); De Schutter, Geert (Universiteit Gent)","","2022","The rapid workability loss of alkali-activated materials (AAM) has been a major obstacle limiting its onsite application. In this study, two conventional SPs (made of polynaphthalene sulfonate (PNS) and lignosulfonate (LS) salts), which have been reported to be effective in some specific AAM mixtures were separately applied in alkali-activated slag (AAS) concretes. A comprehensive testing program was performed to study their effect on reaction kinetics, rheology evolution, and strength development. Results showed sodium silicate-activated AAS mixtures exhibited lower yield stress than those activated by sodium hydroxide. In hydroxide media, PNS and LS remained effective to reduce yield stress and increase slump value, while they both failed to improve the rheological behavior of AAS activated by silicate. Moreover, the inclusion of 2% admixtures did not result in much strength reduction in both activators although LS showed a retardation effect and subsequent increase in the setting time in the fresh state.","Alkali-activated slag concrete; Reaction kinetics; Rheology; Strength development; Superplasticizer","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.","","2022-06-11","","","Materials and Environment","","",""
"uuid:026884d9-0461-4a0e-92cb-bcf40155d09f","http://resolver.tudelft.nl/uuid:026884d9-0461-4a0e-92cb-bcf40155d09f","Future perspectives for alkali‐activated materials: from existing standards to structural applications","Rossi, Laura (Karlsruhe Institut für Technologie); Miranda de Lima Junior, L.C. (TU Delft Materials and Environment); Sun, Yubo (Universiteit Gent); Dehn, Frank (Karlsruhe Institut für Technologie); Provis, John L. (University of Sheffield); Ye, G. (TU Delft Materials and Environment; Universiteit Gent); De Schutter, Geert (Universiteit Gent)","","2022","The production of cement and concrete contributes significantly to global greenhouse gas emissions. Alkali‐activated concretes (AACs) are a family of existing alternative construction materials that could reduce the current environmental impact of Portland cement (PC) production and utilisation. Successful applications of AACs can be found in Europe and the former USSR since the 1950s and more recently in Australia, China and North America, proving their potential as construction materials. However, their utilisation is limited presently by the lack of normative and construction guidelines. Raw materials’ non‐uniform global availability and variable intrinsic properties, coupled with the lack of specific testing methods, raise questions regarding reproducibility and reliability. The mechanical and chemical behaviour of AACs has been investigated extensively over the past decades, strengthening its potential as a sustainable substitute for traditional PC‐based concrete. Although a wide amount of studies demonstrated that AACs could meet and even exceed the performance requirements provided by European design standards, a classification of these broad spectra of materials, as well as new analytical models linking the chemistry of the system components to the mechanical behaviour of the material, still need further development. This report gives an overview of the potential of alkali‐activated systems technology, focusing on the limitations and challenges still hindering their standardisation and wider application in the construction field.","Alkali‐activated concrete; Mechanical performance; Performance‐based standards; Real‐scale applications; Sustainable construction","en","journal article","","","","","","","","","","","Materials and Environment","","",""
"uuid:a17e1e76-90a2-4db2-9e30-230155679c2a","http://resolver.tudelft.nl/uuid:a17e1e76-90a2-4db2-9e30-230155679c2a","Data-Driven Fault Diagnosis of Lithium-Ion Battery Overdischarge in Electric Vehicles","Gan, Naifeng (Beijing Institute of Technology); Sun, S.Z. (Beijing Institute of Technology); Zhang, Zhaosheng (Beijing Institute of Technology); Xu, Shiqi (Beijing Institute of Technology); Liu, Peng (Beijing Institute of Technology); Qin, Z. (TU Delft DC systems, Energy conversion & Storage)","","2022","The overdischarge can significantly degrade a lithium-ion (Li-ion) battery's lifetime. Therefore, it is important to detect the overdischarge and prevent severe damage of the Li-ion battery. Depending on the battery technology, there is a minimum voltage (cutoff voltage) that the battery is allowed to be discharged in common practice. Once the battery voltage is below the cutoff voltage, it is considered as overdischarge. However, overdischarge will not lead to immediate failure of the battery, and if it is not detected, the battery voltage can increase above the cutoff voltage during charging process. How to detect an overdischarge has happened, while the current voltage is larger than the cutoff voltage, thus becomes very challenging. In this article, a machine learning based two-layer overdischarge fault diagnosis strategy for Li-ion batteries in electric vehicles is proposed. The first layer is to detect the overdischarge by comparing the battery voltage with cutoff voltage, like what is utilized in common practice. If the battery voltage is larger than the cutoff voltage, the second layer, which is a detection approach based on eXtreme Gradient Boosting algorithm, is triggered. The second layer is employed to detect the previous overdischarge. The proposed method is validated by real electric vehicle data.","Electric vehicle (EVS); extreme gradient boosting (XGboost); fault diagnosis; lithium-ion battery (LIB); overdischarge","en","journal article","","","","","","","","","","","DC systems, Energy conversion & Storage","","",""
"uuid:893b05eb-e658-4182-b920-7c421b32d807","http://resolver.tudelft.nl/uuid:893b05eb-e658-4182-b920-7c421b32d807","Opportunities and threats to process safety in digitalized process system-an overview","Pasman, Hans (Texas A and M University); Sun, H. (TU Delft Safety and Security Science); Yang, M. (TU Delft Safety and Security Science); Khan, Faisal (Memorial University of Newfoundland; University of Tasmania; Texas A and M University)","","2022","Digital technologies have been reshaping how the process industries operate. The extensive use of physical and information digitalization called by ambitious revolution to redesign process plants significantly transforms the process safety landscape in the process industries. Digitalization depends on the reliable use of data. This becomes a new focus of process safety in digitalized process systems. Digitalization brings the opportunity to generate and collect digital operational data and reduce human operation for effective process monitoring and control for safety assurance. The system's capability of processing massive data becomes essential for process safety. Meanwhile, digitalization increases the complexity of human-computer interaction and consequently leads to new research and practical problems. With standalone processes connected to the Internet of Things, process plants become more attractive to terrorists. This inevitably invites cybersecurity concerns to process safety solutions. This chapter provides a brief overview of these benefits and issues.","","en","book chapter","Elsevier","","","","","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","","","Safety and Security Science","","",""
"uuid:2543476e-6c87-4257-a5a8-f4e5fe4f014a","http://resolver.tudelft.nl/uuid:2543476e-6c87-4257-a5a8-f4e5fe4f014a","OpenSky Report 2021: Insights on ADS-B Mandate and Fleet Deployment in Times of Crisis","Sun, Junzi (TU Delft Control & Simulation); Olive, Xavier (Office National d'Etudes et de Recherches Aerospatiales); Strohmeier, Martin (University of Oxford); Schafer, Matthias (Technische Universität Kaiserslautern); Martinovic, Ivan (University of Oxford); Lenders, Vincent (Armasuisse)","","2021","The year 2020 had been selected by EU and US regulators as the deadline for ADS-B compliant Mode S transponders, following various iterations of ADS-B and Mode S services. It will also be remembered as marking a profound change in civil aviation, when the global virus outbreak triggered an unprecedented slowdown in traffic and brought immense impact on the world economy. Fleets have been grounded and a great number of airplanes went into long-term storage due to travel restrictions. The OpenSky Network has been collecting valuable information regarding ADS-B compliance since 2017. It also acted as an important open data source for studying the aviation industry during these crisis times. In this paper, we analyze years of data collected by the OpenSky Network to provide an overview of the past and current situations in global air traffic with equipage updates, ADS-B implementation, Mode S interrogation practices, and fleet management by airlines.","","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.","","2022-05-16","","","Control & Simulation","","",""
"uuid:6fbc7611-51a6-4508-add7-b3aeec390813","http://resolver.tudelft.nl/uuid:6fbc7611-51a6-4508-add7-b3aeec390813","Fuel Inefficiency Characterisation and Assessment due to Early Execution of Top of Descents: A Case Study for Amsterdam-Schiphol Terminal Airspace using ADS-B data","Dalmau, Ramon (EUROCONTROL); Sun, Junzi (TU Delft Control & Simulation); Prats, Xavier (Technical University of Catalonia - BarcelonaTech (UPC))","","2021","The vertical trajectory plan (altitude and speed) corresponding to the descent phase of a modern airliner is computed by the on-board flight management system while the aircraft is still in cruise. As long as the constraints on the arrival procedure allow, this system plans for an idle descent and the exact location of the (optimal) top of descent (TOD) is determined in this process. In busy terminal airspace, however, air traffic control officers – motivated by the needs to maintain a safe and expeditious flow of aircraft – might require to start the descents before the TOD computed by each particular arriving aircraft. In such situations, most flight guidance systems aim to intercept the original altitude plan from below, by using a shallower descent angle while keeping the speed plan, requiring in this way, additional thrust. This leads, consequently, to higher fuel consumption figures. The objective of this paper is threefold. Firstly, it characterises and quantifies these fuel inefficiencies for an Airbus A320, using accurate aircraft performance data and a trajectory computation software from the manufacturer. Secondly, it proposes a methodology to automatically identify early descents and to extract the key parameters required to compute the fuel inefficiencies by only observing ADS-B (automatic dependent surveillance-broadcast) data. Finally, the method is applied to a case study with 4,139 real ADS-B trajectories in Amsterdam-Schiphol (The Netherlands) terminal airspace; showing that early descents are very frequent and that they increase the fuel consumption by a 5%, in average.","Continuous descent operations; air traffic control; environmental impact; ADS-B","en","conference paper","","","","","","","","","","","Control & Simulation","","",""
"uuid:4f15d68f-1d24-4e31-927e-be9c810d2b40","http://resolver.tudelft.nl/uuid:4f15d68f-1d24-4e31-927e-be9c810d2b40","A Framework to Evaluate Aircraft Trajectory Generation Methods","Olive, Xavier (Office National d'Etudes et de Recherches Aerospatiales); Sun, Junzi (TU Delft Control & Simulation); Murça, Mayara Condé Rocha (Aeronautics Institute of Technology); Krauth, Timothe (Zurich University of Applied Science (ZHAW))","","2021","Aircraft trajectory generation is a widely addressed problem with applications including emergency trajectory generation, collision risk models, air traffic flow and capacity management or airspace design. State of the art methods to generate individual trajectories and optimise some performance or emergency criterion may lack of realism with respect to common situations implemented by air traffic controllers. On the other hand, statistical data-driven methods to generate aircraft trajectories excel at imitating operational practice but may be difficult to implement even in simulations due to aircraft performance limitations. This contribution proposes a common baseline to compare literature and bleeding-edge methods to generate air traffic trajectories. Keeping in mind that the most appropriate criterion should always depend on the targeted application, we present here an extensive set of metrics to evaluate the quality of generated trajectories, before assessing two generation methods in light of these indicators.","air traffic management; trajectory generation; simulation; evaluation; statistical methods","en","conference paper","","","","","","","","","","","Control & Simulation","","",""
"uuid:9e558f2a-1b2e-447f-a703-1550e6d87e1c","http://resolver.tudelft.nl/uuid:9e558f2a-1b2e-447f-a703-1550e6d87e1c","Wind Profile Estimation from Aircraft Derived Data Using Kalman Filters and Gaussian Process Regression","Sun, Junzi (TU Delft Control & Simulation); Marinescu, M. (King Juan Carlos University); Olivares, Alberto (King Juan Carlos University); Staffetti, Ernesto (King Juan Carlos University)","","2021","Accurate wind information is crucial in air traffic management, for instance, to improve trajectory predictability and precision in controlled time of arrival. Nowadays, air traffic management relies on Numerical Weather Prediction, which usually has a low resolution and low update rate. A potential approach for improving the resolution and accuracy of the weather predictions consist in using airborne aircraft as meteorological sensors. Aircraft surveillance systems such as ADS-B and Mode S, transmit data related to weather conditions, automatically or in response to interrogation by air traffic control surveillance radars. In this paper, three different methods for constructing wind profiles from surveillance data have been applied and a comparison between them carried out. The first two methods being modifications of the Kalman filter have been referred to as the Adapted Kalman Filter and Smooth Adapted Kalman Filter. The third one is based on Gaussian process regression. The Kalman filter based methods are able to assimilate nearby data in a straightforward way and update the wind speed estimation in real time. Gaussian process regression is a very flexible and general regression model that can smoothly interpolate in space and extrapolate in time. These three methods have been validated using a test data set, achieving a 50% reduction of the prediction uncertainty in comparison with a baseline model. In addition, the Gaussian process methodology has been applied to reconstruct and forecast the wind field.","Wind Estimation; Kalman Filter; Gaussian Process Regression; Air Traffic Management; ADS-B; Mode S","en","conference paper","","","","","","","","","","","Control & Simulation","","",""
"uuid:8f9c6178-4c17-4966-bd45-e6b59c08c1af","http://resolver.tudelft.nl/uuid:8f9c6178-4c17-4966-bd45-e6b59c08c1af","The Recoverability of Network Controllability","Chen, Anqi (Student TU Delft); Sun, P. (TU Delft Network Architectures and Services); Kooij, Robert (TU Delft Network Architectures and Services; TNO)","","2021","Network recoverability refers to the ability of a network to recover to a desired performance level after suffering topological perturbations such as link failures. The minimum number of driver nodes is a typical metric to denote the network controllability. In this paper, we propose closed-form analytic approximations for the minimum number of driver nodes to investigate the recoverability of network controllability under link-based perturbations in two scenarios: 1) only the links which are damaged in the failure process can be recovered and 2) links can be established between any pair of nodes that have no link between them after the failure process. Results show that our approximations fit well with simulation results both in synthetic networks and real-world networks, such as swarm signaling networks and some communication networks.","recoverability; controllability; complex networks; failures","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.","","2022-07-03","","","Network Architectures and Services","","",""
"uuid:e33d7314-7352-4bbc-8c03-ce4eeae21101","http://resolver.tudelft.nl/uuid:e33d7314-7352-4bbc-8c03-ce4eeae21101","The 1090 Megahertz riddle: A guide to decoding mode S and ADS-B signals: Second edition","Sun, Junzi (TU Delft Control & Simulation)","","2021","Interactive Textbook. In the last twenty years, aircraft surveillance has moved from controller-based interrogation to automatic broadcast. The Automatic Dependent Surveillance-Broadcast (ADS-B) is one of the most common methods for aircraft to report their state information like identity, position, and speed. Like other Mode S communications, ADS-B makes use of the 1090 megahertz transponder to transmit data. The protocol for ADS-B is open, and low-cost receivers can easily be used to intercept its signals. Many recent air transportation studies have benefited from this open data source. However, the current literature does not offer a systematic exploration of Mode S and ADS-B data, nor does it explain the decoding process.
This book tackles this missing area in the literature. It offers researchers, engineers, and enthusiasts a clear guide to understanding and making use of open ADS-B and Mode S data. The first part of this book presents the knowledge required to get started with decoding these signals. It includes background information on primary radar, secondary radar, Mode A/C, Mode S, and ADS-B, as well as the hardware and software setups necessary to gather radio signals. After that, the 17 core chapters of the book investigate the details of all types of ADS-B signals and commonly used Mode S signals. Throughout these chapters, examples and sample Python code are used extensively to explain and demonstrate the decoding process. Finally, the last chapter of the book offers a summary and a brief overview of research topics that go beyond the decoding of these signals.
2O3 and SiO2 play dominant roles in improving the load-bearing capacities and rutting resistance of the PA pavements, and the fillers with high percentages of CaO can improve the ravelling resistance of the PA pavements.","chemical components; correlation analysis; mineral filler; multiscale finite element model; Porous asphalt pavement","en","journal article","","","","","","Accepted Author Manuscript","","2021-08-16","","","Pavement Engineering","","",""
"uuid:b6758b03-fe91-4da0-a0ad-fd311a0ac90d","http://resolver.tudelft.nl/uuid:b6758b03-fe91-4da0-a0ad-fd311a0ac90d","Reducing anionic surfactant adsorption using polyacrylate as sacrificial agent investigated by QCM-D","Liu, Z. (TU Delft ChemE/Advanced Soft Matter; TU Delft OLD ChemE/Organic Materials and Interfaces; China University of Petroleum - Beijing); Hedayati, Pegah (Student TU Delft); Ghatkesar, M.K. (TU Delft Micro and Nano Engineering); Sun, Weichao (University of Copenhagen); Onay, Hayati (Student TU Delft); Groenendijk, Dirk (Shell Global Solutions International B.V.); van Wunnik, Johannes (Shell Global Solutions International B.V.); Sudhölter, Ernst J. R. (TU Delft ChemE/Advanced Soft Matter; TU Delft OLD ChemE/Organic Materials and Interfaces)","","2021","Surfactant losses by adsorption to rock surfaces make surfactant-based enhanced oil recovery economically less feasible. We investigated polyacrylate (PA) as a sacrificial agent in the reduction of anionic surfactant adsorption with focus on calcite surfaces by using quartz crystal microbalance with dissipation monitoring. It was found that the adsorption of the anionic surfactant alcohol alkoxy sulfate (AAS) followed a Langmuir adsorption isotherm, and the adsorbed amount reached saturation above its critical micellar concentration. Adsorption of PA was a much slower process compared to AAS adsorption. Increasing the calcium ion concentration also increased the amount of AAS adsorbed as well as the mass increase rate of PA adsorption. Experimental results combined with density functional theory calculations indicated that calcium cation bridging was important for anionic surfactant AAS and PA adsorption to calcite surfaces. To effectively reduce the amount of surfactant adsorption, it was needed to preflush with PA, rather than by a simultaneous injection. Preflushing with 30 ppm of PA gave a reduction of AAS adsorption of 30% under high salinity (HS, 31,800 ppm) conditions, compared to 8% reduction under low salinity (LS, 3180 ppm) conditions. In the absence of PA, the amount of adsorbed AAS was reduced by already 50% upon changing from HS to LS conditions. Lower calcium ion concentrations, as under LS conditions, contributed to this observation. On different mineral surfaces, PA reduced the AAS adsorption in the order of alumina > calcite > silica. These results offer important insights into mitigating surfactant adsorption using PA polyelectrolyte as sacrificial agent and contribute to improved flooding strategies with reduced surfactant loss.","Divalent cation; Enhanced oil recovery; Polyelectrolyte; QCM-D; Surfactant flooding","en","journal article","","","","","","","","","","","ChemE/Advanced Soft Matter","","",""
"uuid:3abbaf7e-a248-45a7-8c91-0f66647fefb4","http://resolver.tudelft.nl/uuid:3abbaf7e-a248-45a7-8c91-0f66647fefb4","Magnetic seeding coagulation: Effect of Al species and magnetic particles on coagulation efficiency, residual Al, and floc properties","Lv, Miao (Harbin Institute of Technology); Li, Dongyi (Tianjin University); Zhang, Zhaohan (Harbin Institute of Technology); Logan, Bruce E. (The Pennsylvania State University); van der Hoek, J.P. (TU Delft Sanitary Engineering); Sun, Muchen (Harbin Institute of Technology); Chen, Fan (Northwestern Polytechnical University); Feng, Yujie (Harbin Institute of Technology)","","2021","Magnetic seeding coagulation (MSC) process has been used to accelerate flocs sedimentation with an applied magnetic field, offering large handling capacity and low energy consumption. The interactions of three typical Al species, aluminum chloride (AlCl3), Al13O4(OH)247+ polymer (Al13), and (AlO4)2Al28(OH)5618+ polymer (Al30), with magnetic particles (MPs) were examined to clarify the MSC process. In traditional coagulation (TC) process, the aggregation of primary Ala-dissolved organic matter (DOM) complexes with in-situ-formed polynuclear species generated a large average floc size (226 μm), which was proved to be efficient for DOC removal (52.6%). The weak connections between dissolved Ala-DOM complexes and MPs led to the negligible changes of dissolved Al after seeding with MPs in AlCl3. A significant interaction between MPs and Al13 was observed, in which the MPs-Al13-DOM complexes were proposed to be responsible for the significant improvement of DOC removal (from 47% to 52%) and residual total Al reduction (from 1.05 to 0.27 mg Al L−1) with MPs addition. Al30 produced a lower floc fractal dimension (Df = 1.88) than AlCl3 (2.08) and Al13 (1.99) in the TC process, whereas its floc strength (70.9%) and floc recovery (38.5%) were higher than the others. Although more detached fragments were produced with MPs addition, the effective sedimentation of these fragments with the applied magnetic field led to the decrease of residual turbidity and colloidal Al in Al30. The dependence of coagulation behavior to MPs and different Al species can be applied to guide the application of an effective MSC process.","Al species; Coagulation; Floc properties; Magnetic particles; Response surface methodology","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.","","2021-06-17","","","Sanitary Engineering","","",""
"uuid:6d74267e-bd6f-4301-846e-d42e12c62fa4","http://resolver.tudelft.nl/uuid:6d74267e-bd6f-4301-846e-d42e12c62fa4","A multiscale modelling approach to elucidate the mechanism of the oxygen evolution reaction at the hematite-water interface","Sinha, V. (TU Delft Engineering Thermodynamics; DIFFER institute Eindhoven); Sun, D. (Universiteit van Amsterdam); Meijer, E. J. (Universiteit van Amsterdam); Vlugt, T.J.H. (TU Delft Engineering Thermodynamics); Bieberle-Hutter, A. (DIFFER institute Eindhoven)","","2021","Photoelectrochemical (PEC) splitting of water to make hydrogen is a promising clean-energy technology. The oxygen evolution reaction (OER) largely determines the energy efficiency in PEC water-splitting. Hematite, which is a cheap and sustainable semiconductor material with excellent chemical properties, a favourable band gap (2.1 eV) and composed of earth abundant elements is a suitable model photoanode material for studying OER. To understand the design of energy efficient anodes, it is highly desirable to have mechanistic insight into OER at an atomistic level which can be directly connected to experimentally measured quantities. We present a multiscale computational model of OER which connects the thermodynamics and kinetics of elementary charge transfer reactions in OER to kinetics of OER at laboratory length and time scales. We couple density functional theory (DFT) and DFT based molecular dynamics (DFT-MD) simulations with solvent effects at an atomistic level with kinetic Monte Carlo (kMC) simulations at a coarse-grained level in our multiscale model. The time and applied bias potential dependent surface coverage, which are experimentally not known, and the O2 evolution rate during OER at the hematite-water interface are calculated by the multiscale model. Furthermore, the multiscale model demonstrates the effect of explicitly modelling the interaction of water with the electrode surface via direct adsorption. This journal is","","en","journal article","","","","","","Accepted Author Manuscript","","2020-12-23","","","Engineering Thermodynamics","","",""
"uuid:0a0fe7d2-74c1-4ef1-b769-65fe78a5e79d","http://resolver.tudelft.nl/uuid:0a0fe7d2-74c1-4ef1-b769-65fe78a5e79d","Fluidization of fine lactose for dry powder inhalation: A comparison of assisting methods","Zhang, F. (TU Delft ChemE/Product and Process Engineering); La Zara, D. (TU Delft ChemE/Product and Process Engineering); Sun, F. (TU Delft ChemE/Product and Process Engineering); Quayle, Michael J. (Operations); Petersson, Gunilla (Operations); Folestad, Staffan (Operations); van Ommen, J.R. (TU Delft ChemE/Product and Process Engineering)","","2021","Fluidization of cohesive pharmaceutical powders is difficult to achieve and typically requires the introduction of external forces. This study investigates the fluidization of the fine inhalation grade of lactose powders (size range from 0.1-20 μm) that are specifically developed for dry powder inhalation (DPI) applications. The fluidization behaviour of fine lactose powders was evaluated under six conditions: without fluidization aids, with only vertical vibration (VFA), with only a downward-pointing micro-jet (MFA), with both vibration and pre-mixing with coarse particles (VCFA), with both vibration and micro-jet (VMFA), and with the combined assistance of vibration, micro-jet, and addition of coarse particles (VMCFA). The enhancement of fluidization due to the use of different assistance methods is reflected by the increase of bed expansion and the decrease in both the minimum fluidization velocity and agglomerate formation. However, applying micro-jet results in considerable powder losses due to the high fraction of fine particles stuck to the wall. Combining any two assisting methods leads to better fluidization than using a single approach. In particular, the combination of vibration and micro-jet shows the best performance in improving fluidization. Further addition of coarse particles does not play a significant influence on promoting fluidization. Finally, the analysis of the forces acting on the lactose agglomerates shows the enhancement of separation forces by introducing the fluidization assistance, which leads to a decrease in agglomerate size.","fine lactose powder; fluidization; micro-jet; premixing; vibration","en","journal article","","","","","","","","","","","ChemE/Product and Process Engineering","","",""
"uuid:2c178b45-c7f0-4c7b-840f-1753e1f28983","http://resolver.tudelft.nl/uuid:2c178b45-c7f0-4c7b-840f-1753e1f28983","Resilience-based approach to safety barrier performance assessment in process facilities","Sun, Hao (China University of Petroleum (East China)); Wang, Haiqing (China University of Petroleum (East China)); Yang, M. (TU Delft Safety and Security Science); Reniers, G.L.L.M.E. (TU Delft Safety and Security Science; Universiteit Antwerpen; Katholieke Universiteit Leuven)","","2021","The performance assessment of safety barriers is essential to find vulnerable elements in a safety barrier system. Traditional performance assessment approaches mainly focus on using several static indicators for quantifying the performance of safety barriers. However, with the increasing complexity of the system, emerging hazards are highly uncertain, making it challenging for the static indicators to assess the performance of safety barriers. This paper proposes a resilience−based performance assessment method for safety barriers to overcome this problem. Safety barriers are classified according to their functions first. The dynamic Bayesian network (DBN) is then introduced to calculate the availability function under normal and disruption conditions. The ratio of the system's availability, when affected by the disruption, to the initial availability, is used to determine the absorption capacity of the system. The ratio of the quantity of availability recovery to the total quantity of system represents the adaptation and restoration capacity of the system. The system's resilience is represented by the sum of absorption, adaptation, and restoration capacities. The wax oil hydrogenation process is used to demonstrate the applicability of the proposed methodology.","Availability; Bayesian network; Resilience; Safety barrier management","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.","","2022-01-17","","","Safety and Security Science","","",""
"uuid:ff9fe2e3-b83a-4408-b0cd-5c8707c1c517","http://resolver.tudelft.nl/uuid:ff9fe2e3-b83a-4408-b0cd-5c8707c1c517","Element-resolved local lattice distortion in complex concentrated alloys: An observable signature of electronic effects","Oh, Hyun Seok (Seoul National University; Massachusetts Institute of Technology); Odbadrakh, Khorgolkhuu (University of Tennessee; Oak Ridge National Laboratory); Ikeda, Yuji (Max-Planck-Institut für Eisenforschung; University of Stuttgart); Mu, Sai (Oak Ridge National Laboratory); Körmann, F.H.W. (TU Delft Team Marcel Sluiter; Max-Planck-Institut für Eisenforschung); Sun, Cheng Jun (Argonne National Laboratory); Ahn, Heh Sang (Seoul National University); Yoon, Kook Noh (Seoul National University); Ma, Duancheng (Friedrich-Alexander-Universität Erlangen-Nürnberg); Tasan, Cemal Cem (Massachusetts Institute of Technology); Egami, Takeshi (The University of Tennessee Knoxville; Argonne National Laboratory); Park, Eun Soo (Seoul National University)","","2021","Complex concentrated alloys (CCAs) are of growing interest due to their outstanding mechanical properties that exceed the property limits of conventional alloys. Whereas the superior properties are often attributed to severe lattice distortion, to date it is not clear what controls the lattice distortion and how it affects the mechanical properties of CCAs. In this work, we study the element-resolved local lattice distortion (ELLD) in CCAs of 3d transition-metal elements (3d CCAs) by the extended X-ray absorption fine structure experiment and the density-functional theory calculations. We show that ELLD is primarily dependent upon charge transfer among elements and affects the properties through atomic-level pressure and orbital transition. The ELLD provides a qualitative measure of the effective atomic size for explaining element-specific properties and macroscopic properties.","Charge transfer; Complex concentrated alloy; Element-resolved local lattice distortion; Magnetism; Short-range order","en","journal article","","","","","","","","","","","Team Marcel Sluiter","","",""
"uuid:4fd26c10-5e25-42a5-afee-4eeca0a9168d","http://resolver.tudelft.nl/uuid:4fd26c10-5e25-42a5-afee-4eeca0a9168d","Wheel-rail rolling contact behavior induced by both rail surface irregularity and sleeper hanging defects on a high-speed railway line","Yang, Fei (China Academy of Railway Sciences); Wei, Zilong (China Academy of Railway Sciences); Sun, Xianfu (China Academy of Railway Sciences); Shen, C. (TU Delft Railway Engineering); Nunez, Alfredo (TU Delft Railway Engineering)","","2021","In this study, a wheel-rail transient rolling contact model capable of accounting for the nonlinear displacement-force properties of hanging sleepers is proposed. The sleeper hanging status affected by rail irregularities is an input for an analysis of the wheel-rail contact behavior and related rail degradation in terms of plastic deformation and rolling contact fatigue. The results indicate that the severity of sleeper hanging is significantly affected by the geometric characteristics and the relative position with respect to the sleepers of the rail surface irregularity. The sleeper hanging defects aggravate the wheel-rail impact and increase the wheel-rail contact force amplitude, contact patch size, pressure, and von Mises stress, thus exacerbating the plastic deformation of the rail material. It was also found that the sleeper hanging defects rarely affect the distribution of the adhesion-slip states and rolling contact fatigue. The knowledge gained can serve as guidance for evaluating the condition and conducting the maintenance of ballasted railway tracks.","Rail degradation; Sleeper hanging; Uneven settlement; Wheel-rail rolling contact","en","journal article","","","","","","","","","","","Railway Engineering","","",""
"uuid:b2734d80-3504-4553-9be8-673b339a0389","http://resolver.tudelft.nl/uuid:b2734d80-3504-4553-9be8-673b339a0389","Effect of Nb on Microstructural Evolution and Mechanical Properties of Hot-Rolled Quenching and Partitioning Steels Containing Bainite","Chai, Zhisong (Northeastern University); Hu, Jun (Northeastern University); Wang, Chenchong (Northeastern University); Wang, Lingyu (Northeastern University); Sun, Weihua (Shandong Iron & Steel Group Rizhao, Shandong); van der Zwaag, S. (TU Delft Novel Aerospace Materials); Xu, W. (Northeastern University)","","2021","Herein, the effect of Nb content on the phase transformation kinetics, microstructure, and mechanical properties of hot-rolled quenching and partitioning (Q&P) steel is investigated. The characteristics of three C–Mn–Si–Ti steels (0.18C, 2.0Si, 2.6Mn, and 0.015Ti) containing 0, 0.027, or 0.061 wt% Nb are compared. Results reveal that grain boundary pinning by precipitates and Nb solute drag effects refine the austenite grain size during the hot-rolling process; the microstructural refinement is carried over to the final microstructure subjected to the Q&P treatment. The remaining supersaturated Nb suppresses the bainite formation and decreases the final bainite fraction formed in the Q&P process. The microstructural evolution leads to an increase in the ultimate tensile strength (UTS) of the steel containing 0.027 wt% Nb from 1169 to 1228 MPa, while keeping the total elongation at 18%. When the Nb content is increased to 0.061 wt%, the UTS of the steel increases to 1313 MPa, but the elongation at break drops to 16%. The effect is due to the carbon consumption by the Nb precipitates, which causes a decrease in the stability of the retained austenite and reduces the strain hardening at high strain levels.","bainitic transformation; Nb microalloying; quenching and partitioning steel; retained austenite; strength and total elongation","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.","","2022-02-17","","","Novel Aerospace Materials","","",""
"uuid:ce979e6f-0559-437e-b330-46bcd0d7a357","http://resolver.tudelft.nl/uuid:ce979e6f-0559-437e-b330-46bcd0d7a357","Selecting decision trees for power system security assessment","Bugaje, Al-Amin B. (Imperial College London); Cremer, Jochen (TU Delft Intelligent Electrical Power Grids); Sun, Mingyang (Zhejiang University); Strbac, Goran (Imperial College London)","","2021","Power systems transport an increasing amount of electricity, and in the future, involve more distributed renewables and dynamic interactions of the equipment. The system response to disturbances must be secure and predictable to avoid power blackouts. The system response can be simulated in the time domain. However, this dynamic security assessment (DSA) is not computationally tractable in real-time. Particularly promising is to train decision trees (DTs) from machine learning as interpretable classifiers to predict whether the system-wide responses to disturbances are secure. In most research, selecting the best DT model focuses on predictive accuracy. However, it is insufficient to focus solely on predictive accuracy. Missed alarms and false alarms have drastically different costs, and as security assessment is a critical task, interpretability is crucial for operators. In this work, the multiple objectives of interpretability, varying costs, and accuracies are considered for DT model selection. We propose a rigorous workflow to select the best classifier. In addition, we present two graphical approaches for visual inspection to illustrate the selection sensitivity to probability and impacts of disturbances. We propose cost curves to inspect selection combining all three objectives for the first time. Case studies on the IEEE 68 bus system and the French system show that the proposed approach allows for better DT-selections, with an 80% increase in interpretability, 5% reduction in expected operating cost, while making almost zero accuracy compromises. The proposed approach scales well with larger systems and can be used for models beyond DTs. Hence, this work provides insights into criteria for model selection in a promising application for methods from artificial intelligence (AI).","Cost curves; Cost sensitivity; Decision trees; Dynamic security assessment; Machine learning; ROC curve","en","journal article","","","","","","","","","","","Intelligent Electrical Power Grids","","",""
"uuid:cabd41d2-550f-407a-b2d9-ccf54e368293","http://resolver.tudelft.nl/uuid:cabd41d2-550f-407a-b2d9-ccf54e368293","Optimization of intrinsic self-healing silicone coatings by benzotriazole loaded mesoporous silica","Chen, Guangmeng (Northwestern Polytechnical University); Wen, Shifeng (Northwestern Polytechnical University); Ma, Jiacheng (Northwestern Polytechnical University); Sun, Zhiyong (Luoyang Ship Material Research Institute); Lin, Cunguo (Luoyang Ship Material Research Institute); Yue, Zhufeng (Northwestern Polytechnical University); Mol, J.M.C. (TU Delft Team Arjan Mol); Liu, M. (TU Delft Energy Technology; Xi’an Jiaotong University)","","2021","Multifunctional intrinsic self-healing polymers (ISP) are gaining increasing attention these days, and many studies have been devoted to solving the conflict between achieving high mechanical polymer strength and active polymer chain diffusion. In this research, we developed an optimized self-healing composite coating by adding Benzotriazole (BTA) loaded nano silica (SiO2@BTA) to a dynamic cross-linked Polydimethylsiloxane (PDMS) network,which allows substantial and fast healing of the material integrity upon damage due to the hydrogen interaction between urea and BTA. BTA leaching tests demonstrated a longer release profile during the coating service life and corrosion tests in a 3.5 wt% NaCl aqueous solution indicated that the SiO2@BTA modified PDMS coating shows enhanced corrosion protection of carbon steel upon coating damage. Moreover, after addition of SiO2@BTA, the material failure strength increased from ~1.5 MPa to ~5.5 MPa, and the healing efficiency increased from ~59% to ~90% for 24 h healing at room temperature. Above all, this research provides an intrinsic self-healing coating design method to improve the mechanical strength and the self-healing ability of the ISP as well as enhancing the coating's corrosion protection ability.","BTA leaching; Corrosion protection; Mechanical strength; Self-healing coating; Urea hydrogen","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.","","2021-12-07","","","Team Arjan Mol","","",""
"uuid:c4a5b4b7-da40-4437-b89e-f677571ba2ba","http://resolver.tudelft.nl/uuid:c4a5b4b7-da40-4437-b89e-f677571ba2ba","A novel dynamical collaborative optimization method of ship energy consumption based on a spatial and temporal distribution analysis of voyage data","Wang, Kai (Dalian Maritime University); Xu, Hao (Dalian Maritime University); Li, Jiayuan (Dalian Maritime University); Huang, Lianzhong (Dalian Maritime University); Ma, Ranqi (Dalian Maritime University); Jiang, X. (TU Delft Transport Engineering and Logistics); Yuan, Yupeng (MOST; University of Cambridge); Mwero, Ngome A. (Dalian Maritime University; Jomo Kenyatta University of Agriculture and Technology); Sun, Peiting (Dalian Maritime University); Negenborn, R.R. (TU Delft Transport Engineering and Logistics; MOST); Yan, Xinping (MOST)","","2021","It is of significant importance to optimize the energy consumption of ships in order to improve economy and reduce CO2 emissions. However, the energy use of ships is affected by a series of navigational environmental parameters, which have certain spatial and temporal differences and variability. Therefore, the dynamic collaborative optimization method of sailing route and speed, which fully considers the spatial and temporal distribution characteristics of those factors, is of great importance. In this paper, the spatial and temporal distribution characteristics of the environmental factors and their related ship energy consumption profiles are first analyzed. Subsequently, a ship energy consumption model considering various environmental factors is established to realize the prediction of energy use of ships within the navigation region. Then, a novel dynamic collaborative optimization algorithm, which adopts the Model Predictive Control (MPC) strategy and swarm intelligence algorithm, is proposed, to further improve the ship's energy consumption optimization. Finally, a case study is conducted to demonstrate the effectiveness of the proposed method. The results show that the newly developed dynamic collaborative optimization method, which fully considers the continuously time-varying characteristics of environmental and operational parameters, could effectively reduce the energy consumption in comparison to the original operational mode. In addition, the adoption of the MPC strategy produces better performance results compared to the optimization method without the MPC strategy.","energy consumption prediction; intelligent ship; low carbon shipping; Speed optimization; weather routing","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.","","2021-12-01","","","Transport Engineering and Logistics","","",""
"uuid:4a341807-3bad-45b0-adb1-aed96bdee4b2","http://resolver.tudelft.nl/uuid:4a341807-3bad-45b0-adb1-aed96bdee4b2","Effect of ethanol concentration on methane hydrate decomposition: MD simulation insights","Sun, Xiaoliang (China University of Petroleum - Beijing); Zhou, Guanggang (China University of Petroleum - Beijing); Liu, Z. (TU Delft ChemE/Advanced Soft Matter; China University of Petroleum - Beijing); Zhu, Jianwei (China University of Petroleum - Beijing); Guo, Fengzhi (China University of Petroleum - Beijing); Chen, Junqing (China University of Petroleum - Beijing); He, Wenhao (China University of Petroleum - Beijing); Wang, Ning (China University of Petroleum - Beijing); Zhao, Ge (China University of Petroleum - Beijing); Lu, Guiwu (China University of Petroleum - Beijing)","","2021","The controllability of mining is a key factor affecting the commercial application of methane hydrates, and the addition of chemical additives can significantly accelerate the mining process. However, the effect of additive concentration on hydrate decomposition is not yet well understood. In this study, we systematically investigate the effect of ethanol concentration on the decomposition of methane hydrate under varying thermodynamic conditions using molecular dynamics (MD) simulations. To quantitatively characterize the decomposition process and mechanism of methane hydrates, the combination of angular order parameter (AOP), radial distribution function (RDF), mean square displacement (MSD), diffusion coefficients and system energy was for the first time used. The results showed that the addition of ethanol contributed to the formation of methane bubbles and accelerated the decomposition of hydrates. The mass transfer effect of ethanol molecules and the reconstruction of the hydrogen bond network of water molecules determined the stability of hydrates. From 0 to 40 mol% ethanol concentration, the hydrate decomposition increased with increasing the concentration of ethanol. Both increasing the temperature and decreasing the pressure are beneficial to the decomposition of the hydrate system. These results provide the selection of optimal ethanol concentration for the decomposition of methane hydrate and reveal its decomposition mechanism, and shed important light for the controllable production of gas hydrates.","Decomposition; Ethanol concentration; Methane hydrate; Molecular dynamics; Thermodynamics","en","journal article","","","","","","","","","","","ChemE/Advanced Soft Matter","","",""
"uuid:bb534906-a383-47a5-b100-31d9f01c8b3a","http://resolver.tudelft.nl/uuid:bb534906-a383-47a5-b100-31d9f01c8b3a","Cardiac tissue conductivity estimation using confirmatory factor analysis","Sun, M. (TU Delft Signal Processing Systems); de Groot, N.M.S. (Erasmus MC); Hendriks, R.C. (TU Delft Signal Processing Systems)","","2021","Impaired electrical conduction has been shown to play an important role in the development of heart rhythm disorders. Being able to determine the conductivity is important to localize the arrhythmogenic substrate that causes abnormalities in atrial tissue. In this work, we present an algorithm to estimate the conductivity from epicardial electrograms (EGMs) using a high-resolution electrode array. With these arrays, it is possible to measure the propagation of the extracellular potential of the cardiac tissue at multiple positions simultaneously. Given this data, it is in principle possible to estimate the tissue conductivity. However, this is an ill-posed problem due to the large number of unknown parameters in the electrophysiological data model. In this paper, we make use of an effective method called confirmatory factor analysis (CFA), which we apply to the cross correlation matrix of the data to estimate the tissue conductivity. CFA comes with identifiability conditions that need to be satisfied to solve the problem, which is, in this case, estimation of the tissue conductivity. These identifiability conditions can be used to find the relationship between the desired resolution and the required amount of data. Numerical experiments on the simulated data demonstrate that the proposed method can localize the conduction blocks in the tissue and can also estimate the smoother variation in the conductivities. The conductivity values estimated from the clinical data are in line with the values reported in literature and the EGMs reconstructed based on the estimated parameters match well with the clinical EGMs.","Conduction block; Conductivity estimation; Confirmatory factor analysis; Cross power spectral density; Epicardial electrograms","en","journal article","","","","","","","","","","","Signal Processing Systems","","",""
"uuid:416936bf-9906-4cdd-b29d-732e9cf5bc9a","http://resolver.tudelft.nl/uuid:416936bf-9906-4cdd-b29d-732e9cf5bc9a","Towards limiting potential domino effects from single flammable substance release in chemical complexes by risk-based shut down of critical nearby process units","Sun, Hao (China University of Petroleum (East China)); Wang, Haiqing (China University of Petroleum (East China)); Yang, M. (TU Delft Safety and Security Science); Reniers, G.L.L.M.E. (TU Delft Safety and Security Science; Universiteit Antwerpen; Katholieke Universiteit Leuven)","","2021","The explosion load is a significant escalation factor possibly influencing the potential occurrence of domino accidents in chemical plants. It is not economical to install explosion isolation systems (e.g., extinguishing barrier) for all equipment or process units across a chemical plant. Although shutting down all equipment or process unit can prevent an explosion, it may also cause further economic losses. To prevent domino accidents, the process unit that needs to be shut down accurately should be selected, and the normal operation of other units needs to be ensured. A method to select the process unit to be isolated based on the Dimensioning Accidental Load (DAL) is proposed. By calculating the occurrence probability and consequences of the accident scenarios, the DAL of the surrounding units is determined. DAL is used as the impact intensity of the accident unit on the surrounding units. The probit model is used to calculate the damage probability of surrounding units. The case analysis results show that the method of selecting the process unit to be isolated based on DAL quantifies the impact intensity of the exploded unit on surrounding units from probability and consequence. Under the premise of meeting the acceptable risk criteria, the method can determine which units should be shut down and which units can operate normally when a release accident occurs. While preventing domino accidents, economic losses caused by the shutdown of all process units are reduced and a theoretical basis for accident prevention and safe operation of the plant is provided.","Dimensioning accident load; Domino accident; Safety; Vapor cloud explosion","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.","","2021-08-23","","","Safety and Security Science","","",""
"uuid:199eb04b-f8a9-460c-99ff-a906f5c13c98","http://resolver.tudelft.nl/uuid:199eb04b-f8a9-460c-99ff-a906f5c13c98","Relocating operational and damaged bikes in free-floating systems: A data-driven modeling framework for level of service enhancement","Chang, Ximing (Beijing Jiaotong University); Wu, Jianjun (Beijing Jiaotong University); Sun, Huijun (Beijing Jiaotong University); Correia, Gonçalo (TU Delft Transport and Planning); Chen, JianHua (Shenzhen Polytechnic)","","2021","Free-floating bike sharing is an innovative and sustainable travel mode, where shared bikes can be picked up and returned at any proper place on the streets and not just at docking stations. Nevertheless, in these systems, two major problems arise. One is the imbalance of free-floating shared bikes (FFSB) between zones due to one-way trips, the other is the damaged bikes that must be brought for repair. In this study, a modeling framework for dynamic relocating operational and damaged bikes is proposed that starts with predicting the number and location of shared bikes using deep learning algorithms. The demand forecasting model adopts the Encoder-Decoder architecture embedded with the attention mechanism to further enhance the model's prediction ability and flexibility. Then, a data-driven optimization model for FFSB relocations is presented, where the multi-period optimization is applied to dynamically plan the relocation activities throughout the day. A new hybrid metaheuristic algorithm that incorporates variable neighborhood search (VNS) and enhanced simulated annealing (ESA) algorithm is developed for solving the relocating problem, in which satisfactory performance is observed from the numerical example. We test the proposed framework with the real-world FFSB data from Beijing, China. The results show that relocating both operational and damaged bikes timely decreases the probability of users finding damaged bikes in the system, but leads to higher relocation costs. For peak-hours, considering only the operational bikes for relocation is the most effective strategy given the limited relocation resources. It is urgent at those times of the day to focus on providing bikes to clients where they are undersupplied.","Bike relocation; Damaged bikes’ collection; Demand forecasting; Free-floating bike-sharing; Multi-period optimization","en","journal article","","","","","","Accepted author manuscript","","2023-09-30","","","Transport and Planning","","",""
"uuid:a80e59b6-fd3a-4516-8984-439f31145678","http://resolver.tudelft.nl/uuid:a80e59b6-fd3a-4516-8984-439f31145678","Is the tropical cyclone surge in Shanghai more sensitive to landfall location or intensity change?","Wang, Shuai (Imperial College London); Toumi, Ralf (Imperial College London); Ye, Qinghua (TU Delft Coastal Engineering; Deltares); Ke, Q. (TU Delft Hydraulic Structures and Flood Risk); Bricker, J.D. (TU Delft Hydraulic Structures and Flood Risk; University of Michigan); Tian, Zhan (Southern University of Science and Technology); Sun, Laixiang (University of Maryland; SOAS University of London)","","2021","It has been shown that the proportion of intense tropical cyclones (TCs) has been increasing together with a poleward migration of TC track. However, their relative importance to TC surge at landfall remains unknown. Here we examine the sensitivity of TC surge in Shanghai to landfall location and intensity with a new dynamical modelling framework. We find a surge sensitivity of 0.8 m (°N)−1 to landfall location, and 0.1 m (m s−1)−1 to wind speed in Shanghai during landfall. The landfall location and intensity are comparably important to surge variation. However, based on a plausible range of reported trends of TC poleward migration and intensity, the potential surge hazard due to poleward migration is estimated to be about three times larger than that by intensity change. The long-term surge risk in Shanghai is therefore substantially more sensitive to changes of TC track and landfall location than intensity. This may also be true elsewhere and in the future.","climate change; landfall; storm surge; tropical cyclone","en","journal article","","","","","","","","","","","Coastal Engineering","","",""
"uuid:6f2082bf-51d7-4e1b-831f-8429973ce3af","http://resolver.tudelft.nl/uuid:6f2082bf-51d7-4e1b-831f-8429973ce3af","Reinforcement-learning-based adaptive optimal flight control with output feedback and input constraints","Sun, B. (TU Delft Control & Simulation); van Kampen, E. (TU Delft Control & Simulation; TU Delft Control & Operations)","","2021","","","en","journal article","","","","","","","","","","Control & Operations","Control & Simulation","","",""
"uuid:ce32dca4-4301-4804-ba57-2acd93aafbc7","http://resolver.tudelft.nl/uuid:ce32dca4-4301-4804-ba57-2acd93aafbc7","Velocity and turbulence affected by various vegetations in open channel","Sun, Zhilin (Zhejiang University); Meng, Xin (Zhejiang University); Zhou, Y. (TU Delft Applied Mechanics)","","2021","Water energy is a conventional source of source that is widely available in nature. It can be easily converted into high quality secondary energy-electric energy through hydroelectric power stations. Hydropower is not only a widely used conventional energy source, but also a renewable energy source. Moreover, hydroelectric power has no pollution to the environment. Therefore, water energy is an inexhaustible and high-quality energy source among many energy sources in the world. However, vegetation can change flow structure and turbulence characteristics, impacting the use of water energy. In previous researches, few studies have focused on the comparison of velocity and turbulence influenced by various vegetations. Therefore, laboratory experiments were carried out to investigate hydrodynamics affected by submerged rigid vegetation (reed and wooden stick) and merged flexible vegetation (grass and chlorella) under different conditions. The time-averaged velocity distributions of planted floodplain are not logarithmic. Instead, reed and wooden stick followed an ""S-shape""profile, but for grass and chlorella, they presented reverse S-shape profile. For all cases, turbulence is not isotropic and the change law of turbulence intensity is different in different sections.","","en","journal article","","","","","","","","","","","Applied Mechanics","","",""
"uuid:faf5c6e1-3b93-4c35-b5b4-b0c78b59bb86","http://resolver.tudelft.nl/uuid:faf5c6e1-3b93-4c35-b5b4-b0c78b59bb86","First demonstration of l-band high-power limiter with gan schottky barrier diodes (Sbds) based on steep-mesa technology","Sun, Y. (TU Delft Electronic Components, Technology and Materials; Shenzhen Institute of Wide-bandgap Semiconductors; Chinese Academy of Sciences); Kang, Xuanwu (Chinese Academy of Sciences); Deng, Shixiong (National University of Defense Technology; Hebei Semiconductor Research Institute); Zheng, Yingkui (Chinese Academy of Sciences); Wei, Ke (Chinese Academy of Sciences); Xu, Linwang (Hebei Semiconductor Research Institute); Wu, Hao (Chinese Academy of Sciences); Liu, Xinyu (Chinese Academy of Sciences)","","2021","Gallium nitride (GaN) has attracted increased attention because of superior material properties, such as high electron saturation velocity and high electrical field strength, which are promising for high-power microwave applications. We report on a high-performance vertical GaN-based Schottky barrier diode (SBD) and its demonstration in a microwave power limiter for the first time. The fabricated SBD achieved a very low differential specific on-resistance (RON,sp) of 0.21 mΩ·cm2, attributed to the steep-mesa technology, which assists in reducing the spacing between the edge of the anode and cathode to 2 µm. Meanwhile, a low leakage current of ~10−9 A/cm2@−10 V, a high forward current density of 9.4 kA/cm2 at 3 V in DC, and an ideality factor of 1.04 were achieved. Scattering parameter measurements showed that the insertion loss (S21 ) was lower than −3 dB until 3 GHz. In addition, a microwave power limiter circuit with two anti-parallel diodes was built and measured on an alumina substrate. The input power level reached 40 dBm (10 watts) in continuous-wave mode at 2 GHz, with a corresponding leakage power of 27.2 dBm (0.5 watts) at the output port of the limiter, exhibiting the great potential of GaN SBD in microwave power limiters.","GaN SBD; High power; L band; Schottky diode limiter; Vertical","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:fa187565-2f24-4b6b-9360-ae177687e9ab","http://resolver.tudelft.nl/uuid:fa187565-2f24-4b6b-9360-ae177687e9ab","Low Leakage and High Forward Current Density Quasi-Vertical GaN Schottky Barrier Diode With Post-Mesa Nitridation","Kang, Xuanwu (Fudan University; Chinese Academy of Sciences); Sun, Y. (TU Delft Electronic Components, Technology and Materials; Shenzhen Institute of Wide-bandgap Semiconductors; Chinese Academy of Sciences); Zheng, Yingkui (Chinese Academy of Sciences); Wei, Ke (Chinese Academy of Sciences); Wu, Hao (Fudan University; Chinese Academy of Sciences); Zhao, Yuanyuan (Chinese Academy of Sciences); Liu, Xinyu (Chinese Academy of Sciences); Zhang, Kouchi (Fudan University)","","2021","In this brief, a high-performance quasi-vertical GaN Schottky barrier diode (SBD) on sapphire substrate with post-mesa nitridation process is reported, featuring a low damaged sidewall with extremely low leakage current. The fabricated SBD with a drift layer of 1 μm has achieved a very high ON/OFF current ratio (Iscriptscriptstyle ON/Iscriptscriptstyle OFF of 1012 with a low leakage current of ∼ 10-9 A/cm2@-10 V, high forward current density of 5.2 kA/cm2 at 3 V in dc, a low differential specific ON-resistance (Rscriptscriptstyle ONsp) of 0.3 m Ω cm2, and ideality factor of 1.04. In addition, a transmission-line-pulse (TLP) I-V test was carried out and 53 kA/cm2 at 30 V in pulsed measurement was obtained without device failure, exhibiting a great potential for high power applications.","GaN; high forward current density; leakage; mesa; quasi; Schottky barrier diode (SBD); transmission-line-pulse (TLP); vertical.","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:59b258a3-d0ac-416c-9fe1-94e837e38483","http://resolver.tudelft.nl/uuid:59b258a3-d0ac-416c-9fe1-94e837e38483","Drug powders with tunable wettability by atomic and molecular layer deposition: From highly hydrophilic to superhydrophobic","La Zara, D. (TU Delft ChemE/Product and Process Engineering); Zhang, F. (TU Delft ChemE/Product and Process Engineering); Sun, F. (TU Delft ChemE/Product and Process Engineering); Bailey, Maximilian R. (ETH Zürich; Student TU Delft); Quayle, Michael J. (Operations); Petersson, Gunilla (Operations); Folestad, Staffan (Operations); van Ommen, J.R. (TU Delft ChemE/Product and Process Engineering)","","2021","The wettability of pharmaceuticals is a key physical property which influences their dissolution rate, dispersibility, flowability and solid-state stability. Here, we provide a platform of surface nanoengineering methods capable of tuning the wettability of drug powders from high hydrophilicity to superhydrophobicity with drug loadings up to 95–99%. Specifically, we functionalize gram-scale micronized budesonide, a commercial active pharmaceutical ingredient for respiratory diseases, in a vibrated fluidized bed reactor with inorganic Al2O3, TiO2 and SiO2 by atomic layer deposition (ALD), organic poly(ethylene terephthalate) (PET) by molecular layer deposition (MLD) and inorganic/organic titanicone by hybrid ALD/MLD. Transmission electron microscopy shows the formation of smooth and uniform films for each deposition process without significantly affecting the surface morphology of the budesonide particles. Crucially, the deposition processes do not alter the solid-state structure and cytocompatibility of budesonide. The ceramic ALD films are able to convert the originally hydrophobic budesonide into highly hydrophilic powders with water contact angles (WCAs) of ~10° within a few seconds. The purely organic PET films grown via MLD deliver superhydrophobic powders with a WCA of 145–150°. In contrast, the titanicone hybrid ALD/MLD films lead to mild hydrophilicity with WCAs ranging from ~80° to ~60°. Modifying the wetting properties of inhaled drug powders such as budesonide is relevant to improve bioavailability, enhance the dispersion of formulations in suspension-based inhalers or prevent moisture interactions in dry powder inhalers. Moreover, by tuning the surface chemical composition at the atomic or molecular level, particle ALD, MLD and hybrid ALD/MLD enable control over powder wettability for several pharmaceutical dosage forms with applications in oral, orally inhaled and parenteral delivery.","Atomic layer deposition; Budesonide; Hydrophilic/hydrophobic; Molecular layer deposition; Pharmaceutical powder; Wetting","en","journal article","","","","","","","","","","","ChemE/Product and Process Engineering","","",""
"uuid:d4d48a96-d622-4f59-b505-9c9ea5a9c7a7","http://resolver.tudelft.nl/uuid:d4d48a96-d622-4f59-b505-9c9ea5a9c7a7","High-power and broadband microwave detection with a quasi-vertical GaN Schottky barrier diode by novel post-mesa nitridation","Sun, Y. (TU Delft Electronic Components, Technology and Materials; Shenzhen Institute of Wide-bandgap Semiconductors; Chinese Academy of Sciences); Kang, Xuanwu (Chinese Academy of Sciences); Deng, Shixiong (National University of Defense Technology; Hebei Semiconductor Research Institute); Zheng, Yingkui (Chinese Academy of Sciences); Wei, Ke (Chinese Academy of Sciences); Xu, Linwang (Hebei Semiconductor Research Institute); Wu, Hao (Chinese Academy of Sciences); Liu, Xinyu (Chinese Academy of Sciences)","","2021","We report a high-performance GaN Schottky barrier diode (SBD) on a sapphire substrate with a novel post-mesa nitridation technique and its application in a high-power microwave detection circuit. The fabricated SBD achieved a very high forward current density of 9.19 kA cm-2 at 3 V, a low specific on-resistance (RON,sp) of 0.22 mO cm2 and breakdown voltage of 106 V. An extremely high output current of 400 mA was obtained when the detected power reached 38.4 dBm@3 GHz in pulsed-wave mode with a small anode diameter of 70 μm. Meanwhile, broadband detection at frequencies ranging from 1 to 6 GHz was achieved at 33 dBm in continuous-wave mode.","GaN; Microwave power detector; Quasi; Schottky barrier diode (SBD); Vertical","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:29f976a5-e242-4756-8553-fa0ec478029c","http://resolver.tudelft.nl/uuid:29f976a5-e242-4756-8553-fa0ec478029c","Intelligent adaptive optimal control using incremental model-based global dual heuristic programming subject to partial observability","Sun, B. (TU Delft Control & Simulation); van Kampen, E. (TU Delft Control & Simulation)","","2021","The scarcity of information regarding dynamics and full-state feedback increases the demand for a model-free control technique that can cope with partial observability. To deal with the absence of prior knowledge of system dynamics and perfect measurements, this paper develops a novel intelligent control scheme by combining global dual heuristic programming with an incremental model-based identifier. An augmented system consisting of the unknown nonlinear plant and unknown varying references is identified online using a locally linear regression technique. The actor–critic is implemented using artificial neural networks, and the actuator saturation constraint is addressed by exploiting a symmetrical sigmoid activation function in the output layer of the actor network. Numerical experiments are conducted by applying the proposed method to online adaptive optimal control tasks of an aerospace system. The results reveal that the developed method can deal with partial observability with performance comparable to the full-state feedback control, while outperforming the global model-based method in stability and adaptability.","Adaptive optimal control; Artificial neural network; Global dual heuristic programming; Intelligent control; Partial observability","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:d8a627eb-2817-42cc-bdda-e902f5f6af38","http://resolver.tudelft.nl/uuid:d8a627eb-2817-42cc-bdda-e902f5f6af38","Controlled Pulmonary Delivery of Carrier-Free Budesonide Dry Powder by Atomic Layer Deposition","La Zara, D. (TU Delft ChemE/Product and Process Engineering); Sun, F. (TU Delft ChemE/Product and Process Engineering); Zhang, F. (TU Delft ChemE/Product and Process Engineering); Franek, Frans (Operations); Balogh Sivars, Kinga (Operations); Horndahl, Jenny (Operations); Bates, Stephanie (Operations); Brännström, Marie (Operations); van Ommen, J.R. (TU Delft ChemE/Product and Process Engineering)","","2021","Ideal controlled pulmonary drug delivery systems provide sustained release by retarding lung clearance mechanisms and efficient lung deposition to maintain therapeutic concentrations over prolonged time. Here, we use atomic layer deposition (ALD) to simultaneously tailor the release and aerosolization properties of inhaled drug particles without the need for lactose carrier. In particular, we deposit uniform nanoscale oxide ceramic films, such as Al2O3, TiO2, and SiO2, on micronized budesonide particles, a common active pharmaceutical ingredient for the treatment of respiratory diseases. In vitro dissolution and ex vivo isolated perfused rat lung tests demonstrate dramatically slowed release with increasing nanofilm thickness, regardless of the nature of the material. Ex situ transmission electron microscopy at various stages during dissolution unravels mostly intact nanofilms, suggesting that the release mechanism mainly involves the transport of dissolution media through the ALD films. Furthermore, in vitro aerosolization testing by fast screening impactor shows a μ2-fold increase in fine particle fraction (FPF) for each ALD-coated budesonide formulation after 10 ALD process cycles, also applying very low patient inspiratory pressures. The higher FPFs after the ALD process are attributed to the reduction in the interparticle force arising from the ceramic surfaces, as evidenced by atomic force microscopy measurements. Finally, cell viability, cytokine release, and tissue morphology analyses verify a safe and efficacious use of ALD-coated budesonide particles at the cellular level. Therefore, surface nanoengineering by ALD is highly promising in providing the next generation of inhaled formulations with tailored characteristics of drug release and lung deposition, thereby enhancing controlled pulmonary delivery opportunities.","atomic layer deposition; budesonide; controlled release; dry powder inhaler; inhalation; isolated perfused rat lung; particle-to-cell deposition","en","journal article","","","","","","","","","","","ChemE/Product and Process Engineering","","",""
"uuid:03602775-903c-45fa-b7b7-578f6bd8e678","http://resolver.tudelft.nl/uuid:03602775-903c-45fa-b7b7-578f6bd8e678","Impacts of the Silk Road pattern on the interdecadal variations of the atmospheric heat source over the Tibetan Plateau","Han, Yizhe (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Ma, Weiqiang (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Yang, Yaoxian (Chinese Academy of Science); Ma, Yaoming (Chinese Academy of Sciences; University of Chinese Academy of Sciences; CAS Center for Excellence in Tibetan Plateau Earth Sciences); Xie, Zhipeng (Chinese Academy of Sciences); Sun, Genhou (Sun Yat-sen University; Southern Marine Science and Engineering Guangdong Laboratory); Menenti, M. (TU Delft Optical and Laser Remote Sensing; Chinese Academy of Sciences); Su, Bob (University of Twente; Chang'an University)","","2021","This study aimed to investigate the relationship between the boreal summer Silk Road Pattern (SRP) and the atmospheric heat (<Q1>) over the Tibetan Plateau (TP) region, using 5 reanalysis datasets over the period 1979–2019. Our results indicate an interdecadal change of boreal summer SRP over the Eurasian region, with a regime shift in the spatial structure at around 1997. Meanwhile, the summer <Q1> anomaly also shows a clear interdecadal increasing trend over the TP region, which is highly correlated with the interdecadal variation of the SRP. The impact of the SRP on the summer <Q1> was also investigated. The regime shift of the SRP would have generated circulation anomalies over the Lake Baikal region in 500 hPa, which would have inhibited moisture transport across the eastern boundary of the TP. Meanwhile, Indian Summer Monsoon (ISM) would also transport water vapor through the southern boundary of the TP and increased the contents of water vapor in the TP. Associated with this increase in moisture, the change of vertical motion would result in large plenty of precipitation, which released latent heat and enhanced <Q1> in summer. Thus, the regime shift in summer SRP was an important factor contributing to changes in summer <Q1> over the TP in recent decades.","Atmospheric heat source; Interdecadal variability; Reanalysis datasets; Silk Road Pattern (SRP); Tibetan Plateau","en","journal article","","","","","","","","","","","Optical and Laser Remote Sensing","","",""
"uuid:456d53df-8a2c-41c8-86c9-4ba4a50732c7","http://resolver.tudelft.nl/uuid:456d53df-8a2c-41c8-86c9-4ba4a50732c7","Using Machine Learning to Quantify the Robustness of Network Controllability","Dhiman, Ashish (Student TU Delft); Sun, P. (TU Delft Network Architectures and Services); Kooij, Robert (TU Delft Network Architectures and Services)","Renault, Éric (editor); Boumerdassi, Selma (editor); Mühlethaler, Paul (editor)","2021","This paper presents machine learning based approximations for the minimum number of driver nodes needed for structural controllability of networks under link-based random and targeted attacks. We compare our approximations with existing analytical approximations and show that our machine learning based approximations significantly outperform the existing closed-form analytical approximations in case of both synthetic and real-world networks. Apart from targeted attacks based upon the removal of so-called critical links, we also propose analytical approximations for out-in degree-based attacks.","Driver nodes; Machine learning; Network controllability; Network robustness","en","conference paper","Springer","","","","","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.","","2021-11-29","","","Network Architectures and Services","","",""
"uuid:f0bdac3d-376d-4b24-9241-3a1e35731373","http://resolver.tudelft.nl/uuid:f0bdac3d-376d-4b24-9241-3a1e35731373","Quadrotor Fault Tolerant Flight Control and Aerodynamic Model Identification","Sun, S. (TU Delft Control & Simulation)","de Croon, G.C.H.E. (promotor); de Visser, C.C. (copromotor); Delft University of Technology (degree granting institution)","2020","As Multi-rotor Unmanned Aerial Vehicles, or drones, are gradually becoming more popular in civilian applications, the safety of these flying machines becomes a significant concern. Such drones are powered by multiple rotors to generate lift and control torques. Hence, the failure of rotors can severely threaten their flying safety. Direct consequences of rotor failures are loss-of-control and a subsequent crash if no ad-hoc flight control method can take over. Such a method, built on the principles of Fault Tolerant Control (FTC), is thus essential to improving the safety of multi-rotor drones. Fixed-pitch quadrotors are the simplest type of multi-rotor drones and have been extensively used in various applications thanks to their simplicity and higher energy efficiency. However, they suffer most from rotor failures since it requires a minimum of four fixed-pitch rotors to achieve full attitude control. Therefore, devising FTC algorithms for quadrotors presents a significant challenge. As there have been many efforts to develop FTC for quadrotors flying in nearhover conditions, a primary objective of this thesis is further expanding the capability of FTC methods to high-speed conditions where significant aerodynamic effects arise that brings large model uncertainties to the control algorithm. The high-speed flight conditions can be, for instance, the cruising phase of a quadrotor (e.g., delivery drone). Once rotor failure occurs, these aerodynamic effects can adversely impact the performance of FTC methods, and even drive the damaged quadrotor into upset conditions with abnormal attitude and angular rates. On the one hand, it is essential to improve state-of-art FTC methods withstanding significant aerodynamic effects as well as possible large initial disturbances. On the other hand, these aerodynamic effects need to be further investigated and modeled to facilitate the development of FTC in high-speed conditions. These two aspects constitute the two major parts of this thesis...","Quadrotor; Safety; Control; Modeling","en","doctoral thesis","","978-94-6384-181-8","","","","","","","","","Control & Simulation","","",""
"uuid:e8068b85-f8f6-4ebd-951f-e9216eb2cc2c","http://resolver.tudelft.nl/uuid:e8068b85-f8f6-4ebd-951f-e9216eb2cc2c","Design, fabrication and characterizations of AlGaN/GaN heterostructure sensors","Sun, J. (TU Delft Electronic Components, Technology and Materials)","Sarro, Pasqualina M (promotor); Zhang, Kouchi (promotor); Delft University of Technology (degree granting institution)","2020","The microelectronics industry, next to the powerful, continuously scaling of integrated circuits, is currently evolving in the diversification of integrated functions, generally referred to as more than Moore (MtM). MtM concerns all technologies enabling microsystems to be elevated to a higher integration level, and with small package size, lower power consumption and lower cost. Microelectromechanical (MEMS) are crucial within this development. While Si has proven to be the primary contestant in the MEMS sensor market, there is a growing need for sensors operating at conditions beyond the limits of Si. Si-based micro-sensors cannot operate in harsh environments such as high temperature, high radiation, high pressure, and chemically corrosive conditions. Wide bandgap semiconductors such as Gallium Nitride (GaN) are potential candidates to replace silicon due to their specific characteristics and proven performance in the power or LED applications. The research objective of this thesis is to develop a MEMS sensor platform utilizing GaN-based materials. The design, fabrication, packaging, and measurement of pressure, deep UV photodetector, and gas sensors are presented and discussed.","AlGaN/GaN; HEMT; MEMS; Micro-heater; Pressure sensor; UV sensor; Gas sensor","en","doctoral thesis","","978-94-6402-350-3","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:d5b4a20d-bd1d-4eba-a41f-50fdd21cac7c","http://resolver.tudelft.nl/uuid:d5b4a20d-bd1d-4eba-a41f-50fdd21cac7c","Graph-time spectral analysis for atrial fibrillation","Sun, M. (TU Delft Signal Processing Systems); Isufi, E. (TU Delft Multimedia Computing); de Groot, N.M.S. (TU Delft Biomechanical Engineering; Erasmus MC); Hendriks, R.C. (TU Delft Signal Processing Systems)","","2020","Atrial fibrillation is a clinical arrhythmia with multifactorial mechanisms still unresolved. Time-frequency analysis of epicardial electrograms has been investigated to study atrial fibrillation. However, deeper understanding can be achieved by incorporating the spatial dimension. Unfortunately, the physical models describing the spatial relations of atrial fibrillation signals are complex and non-linear; hence, conventional signal processing techniques to study electrograms in the joint space, time, and frequency domain are less suitable. In this study, we wish to put forward a radically different approach to analyze atrial fibrillation with a higher-level model. This approach relies on graph signal processing to represent the spatial relations between epicardial electrograms. To capture the frequency content along both the time and graph domain, we propose the joint graph and short-time Fourier transform. The latter allows us to analyze the spatial variability of the electrogram temporal frequencies. With this technique, we found the spatial variation of the atrial electrograms decreases during atrial fibrillation since the high temporal frequencies of the atrial waves reduce. The proposed analysis further confirms that the ventricular activity is smoother over the atrial area compared with the atrial activity. Besides using the proposed graph-time analysis to conduct a first study on atrial fibrillation, we demonstrate its potential by applying it to the cancellation of ventricular activity from the atrial electrograms. Experimental results on simulated and real data further corroborate our findings in this atrial fibrillation study.","Atrial activity extraction; Atrial fibrillation; Graph signal processing; Graph-time signal processing; Spectral analysis","en","journal article","","","","","","","","2022-03-06","","Biomechanical Engineering","Signal Processing Systems","","",""
"uuid:e53b59af-1d2f-409b-9ba8-7091682b8a0d","http://resolver.tudelft.nl/uuid:e53b59af-1d2f-409b-9ba8-7091682b8a0d","Incremental model-based global dual heuristic programming with explicit analytical calculations applied to flight control","Sun, B. (TU Delft Control & Simulation); van Kampen, E. (TU Delft Control & Simulation)","","2020","A novel adaptive dynamic programming method, called incremental model-based global dual heuristic programming, is proposed to generate a self-learning adaptive flight controller, in the absence of sufficient prior knowledge of system dynamics. An incremental technique is employed for online local dynamics identification, instead of the artificial neural networks commonly used in global dual heuristic programming, to enable a fast and precise learning. On the basis of the identified model, two neural networks are adopted to facilitate the implementation of the self-learning controller, by approximating the cost-to-go and the control policy, respectively. The required derivatives of cost-to-go are computed by explicit analytical calculations based on differential operations. Both methods are applied to an online attitude tracking control problem of a nonlinear aerospace system and the results show that the proposed method outperforms conventional global dual heuristic programming in tracking precision, online learning speed, robustness to different initial states and adaptability for fault-tolerant control problems.","Analytical calculation; Artificial neural network; Flight control; Global dual heuristic programming; Incremental technique","en","journal article","","","","","","","","2022-01-05","","","Control & Simulation","","",""
"uuid:9f03fa61-1501-4d81-9c11-a1a191797752","http://resolver.tudelft.nl/uuid:9f03fa61-1501-4d81-9c11-a1a191797752","Public Space in Chinese Urban Design Theory after 1978: a compressed transculturation","Sun, Wenwen (TU Delft Theory, Territories & Transitions)","","2020","The 1978 economic reform not only propelled a rapid urban development in China but also unlocked vast possibilities for global exchanges of knowledge and techniques in the fields of architecture and urban design. To establish a theoretical and empirical understanding of the notion of public space, Chinese scholars and design practitioners have related to design theories and exemplary cases through direct and indirect contact with the Western context in the four decades since 1978. This paper analyses how the Western notion of public space encountered Chinese urban design and was rapidly negotiated on the level of concept through theoretical developments. The process began with a loose transmission of design knowledge and technique while uprooting the embedded cultural background; it then developed into a situated and structured framework of knowledge in the specific context of modern China. This paper argues that the notion of public space in Chinese urban design culture has articulated the substance of compressed transculturation, not only through its compact four-decade-long development trajectory, but also as a result of both acculturation and deculturation.","","en","journal article","","","","","","","","","","","Theory, Territories & Transitions","","",""
"uuid:0416a411-584f-47a4-968c-d82af798dc51","http://resolver.tudelft.nl/uuid:0416a411-584f-47a4-968c-d82af798dc51","Joint migration inversion: Features and challenges","Sun, Yimin (Aramco Overseas Company B.V.); Kim, Young Seo (Saudi Aramco); Qu, S. (TU Delft ImPhys/Computational Imaging; TU Delft ImPhys/Medical Imaging); Verschuur, D.J. (TU Delft ImPhys/Computational Imaging)","","2020","Joint migration inversion is a recently proposed technology, accommodating velocity model building and seismic migration in one integrated process. Different from the widely accepted full waveform inversion technology, it uses imaging parameters, i.e. velocities and reflectivities of the subsurface, to parameterize its solution space. The unique feature of this new technology is its explicit capability to exploit multiples in its inversion scheme, which are treated as noise by most current technologies. In this paper, we comprehensively evaluate the state-of-the-art joint migration inversion technology from various angles: we first benchmark its performance, on both velocity model building and seismic imaging, against that of the well-accepted workflow comprising full waveform inversion and reverse-time migration using a fully controlled 2D realistic synthetic dataset. Next, we demonstrate its application on a 2D field dataset. Last, we use another 2D synthetic dataset to clearly illustrate the challenges the current joint migration inversion technology is facing. With this paper, we transparently reveal the pros of cons of the current joint migration inversion, and we will also point out the imminent research directions joint migration inversion technology should focus on in the next phase for it to be more widely accepted by the geophysics community.","Imaging; Joint migration inversion; Velocity model building","en","journal article","","","","","","","","","","","ImPhys/Computational Imaging","","",""
"uuid:b0bb4a45-958a-4a46-811f-a50e8e9e65ab","http://resolver.tudelft.nl/uuid:b0bb4a45-958a-4a46-811f-a50e8e9e65ab","A first comparison of TROPOMI aerosol layer height (ALH) to CALIOP data","Nanda, S. (TU Delft Atmospheric Remote Sensing); de Graaf, M. (Royal Netherlands Meteorological Institute (KNMI)); Veefkind, j. Pepijn (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI)); Sneep, Maarten (Royal Netherlands Meteorological Institute (KNMI); S&T Corporation); Sun, J. (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI)); Levelt, Pieternel Felicitas (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI))","","2020","The TROPOspheric Monitoring Instrument (TROPOMI) level-2 aerosol layer height (ALH) product has now been released to the general public. This product is retrieved using TROPOMI's measurements of the oxygen A-band, radiative transfer model (RTM) calculations augmented by neural networks and an iterative optimal estimation technique. The TROPOMI ALH product will deliver ALH estimates over cloud-free scenes over the ocean and land that contain aerosols above a certain threshold of the measured UV aerosol index (UVAI) in the ultraviolet region. This paper provides background for the ALH product and explores its quality by comparing ALH estimates to similar quantities derived from spaceborne lidars observing the same scene. The spaceborne lidar chosen for this study is the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission, which flies in formation with NASA's A-train constellation since 2006 and is a proven source of data for studying ALHs. The influence of the surface and clouds is discussed, and the aspects of the TROPOMI ALH algorithm that will require future development efforts are highlighted. A case-by-case analysis of the data from the four selected cases (mostly around the Saharan region with approximately 800 co-located TROPOMI pixels and CALIOP profiles in June and December 2018) shows that ALHs retrieved from TROPOMI using the operational Sentinel-5 Precursor Level-2 ALH algorithm is lower than CALIOP aerosol extinction heights by approximately 0.5km. Looking at data beyond these cases, it is clear that there is a significant difference when it comes to retrievals over land, where these differences can easily go over 1km on average.","","en","journal article","","","","","","","","","","","Atmospheric Remote Sensing","","",""
"uuid:be9aebdf-f535-4b12-b3d4-acaf01cd9c81","http://resolver.tudelft.nl/uuid:be9aebdf-f535-4b12-b3d4-acaf01cd9c81","On the application of the window of opportunity and complex network to risk analysis of process plants operations during a pandemic","Sun, Hao (China University of Petroleum (East China)); Wang, Haiqing (China University of Petroleum (East China)); Yang, M. (TU Delft Safety and Security Science); Reniers, G.L.L.M.E. (TU Delft Safety and Security Science; Universiteit Antwerpen; Katholieke Universiteit Leuven)","","2020","To quantify the pandemic specific impact with respect to the risk related to the chemical industry, a novel risk analysis method is proposed. The method includes three parts. Firstly, the two types of “window of opportunity” (WO) theory is proposed to divide an accident life cycle into two parts. Then, a qualitative risk analysis is conducted based on WO theory to determine possible risk factors, evolution paths and consequences. The third part is a quantitative risk analysis based on a complex network model, integrating two types of WO. The Fuzzy set theory is introduced to calculate the failure probabilities of risk factors and the concept of risk entropy is used to represent the uncertainty. Then the Dijkstra algorithm is used to calculate the shortest path and the corresponding probability of the accident. The proposed method is applied to the SCR denitrition liquid ammonia storage and transportation system. The results show that it is a comprehensive method of quantitative risk analysis and it is applicable to risk analysis during the pandemic.","Accident evolution; Complex network; Pandemic; Risk analysis; Risk entropy; Window of opportunity","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.","","2021-04-13","","","Safety and Security Science","","",""
"uuid:6110e71e-9f4a-4441-897a-30048a776c8a","http://resolver.tudelft.nl/uuid:6110e71e-9f4a-4441-897a-30048a776c8a","A global semi-empirical glacial isostatic adjustment (GIA) model based on Gravity Recovery and Climate Experiment (GRACE) data","Sun, Yu (Fuzhou University); Riva, R.E.M. (TU Delft Physical and Space Geodesy)","","2020","The effect of glacial isostatic adjustment (GIA) on the shape and gravity of the Earth is usually described by numerical models that solve for both glacial evolution and Earth's rheology, being mainly constrained by the geological evidence of local ice extent and globally distributed sea level data, as well as by geodetic observations of Earth's rotation. In recent years, GPS and GRACE observations have often been used to improve those models, especially in the context of regional studies. However, consistency issues between different regional models limit their ability to answer questions from global-scale geodesy. Examples are the closure of the sea level budget, the explanation of observed changes in Earth's rotation, and the determination of the origin of the Earth's reference frame. Here, we present a global empirical model of present-day GIA, solely based on GRACE data and on geoid fingerprints of mass redistribution.We will show how the use of observations from a single space-borne platform, together with GIA fingerprints based on different viscosity profiles, allows us to tackle the questions from globalscale geodesy mentioned above. We find that, in the GRACE era (2003-2016), freshwater exchange between land and oceans has caused global mean sea level to rise by 1:2±0:2mmyr-11, the geocentre to move by 0:4± 0:1mmyr-11, and the Earth's dynamic oblateness (J2) to increase by 6:0±0:4×10-11 yr-11,.","","en","journal article","","","","","","","","","","","Physical and Space Geodesy","","",""
"uuid:882b3d68-ab41-4a14-9043-639c11d3e546","http://resolver.tudelft.nl/uuid:882b3d68-ab41-4a14-9043-639c11d3e546","The Longitudinal Profile of a Prograding River and Its Response to Sea Level Rise","Gao, Weilun (Beijing Normal University; Ministry of Education, Shandong); Li, Dongxue (Beijing Normal University; Ministry of Education, Shandong); Wang, Zhengbing (TU Delft Coastal Engineering; Beijing Normal University; Deltares); Nardin, William (University of Maryland Center for Environmental Science); Shao, Dongdong (Beijing Normal University; Ministry of Education, Shandong); Sun, Tao (Beijing Normal University; Ministry of Education, Shandong); University, Beijing (Beijing Normal University); Cui, Baoshan (Beijing Normal University; Ministry of Education, Shandong)","","2020","River longitudinal profile, a key morphological characteristic of the river channel, is subject to river mouth progradation. Given the increasing influence of human activities and climate change on this critical downstream control, understanding its effects on the evolution of the longitudinal profile is imperative. A general theoretical framework is proposed to quantify the relevant effects, which is tested by numerical experiment and compared with field, numerical and laboratory data from the literature. The results suggest the existence of a critical ratio of accommodation space to sediment supply of approximately 0.5, above which the typical concave upward profile tends to form. Further analyses show that sea level rise tends to increase the concavity of the longitudinal profile of a river with a relatively low equilibrium bed slope and progradation rate.","","en","journal article","","","","","","","","2021-04-21","","","Coastal Engineering","","",""
"uuid:c3ff6240-e5d7-46fa-a47c-77304f5c1c49","http://resolver.tudelft.nl/uuid:c3ff6240-e5d7-46fa-a47c-77304f5c1c49","Estimating aircraft drag polar using open flight surveillance data and a stochastic total energy model","Sun, Junzi (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Operations); Ellerbroek, Joost (TU Delft Control & Simulation)","","2020","In air traffic management research, aircraft performance models are often used to generate and analyze aircraft trajectories. Although a crucial part of the aircraft performance model, the aerodynamic property of aircraft is rarely available for public research purposes, as it is protected by aircraft manufacturers for commercial reasons. In many studies, a simplified quadratic drag polar model is assumed to compute the drag of an aircraft based on the required lift. In this paper, using surveillance data, we take on the challenge of estimating the drag polar coefficients based on a novel stochastic total energy model that employs Bayesian computing. The method is based on a stochastic hierarchical modeling approach, which is made possible given accurate open aircraft surveillance data and additional analytical models from the literature. Using this proposed method, the drag polar models for 20 of the most common aircraft types are estimated and summarized. By combining additional data from the literature, we propose additional methods allowing aircraft total drag to be calculated under other configurations, such as when flaps and landing gears are deployed. We also include additional models allowing the calculation of wave drag caused by compressibility at high Mach number. Though uncertainties exist, it has been found that the estimated drag polars agree with existing models, as well as CFD simulation results. The trajectory data, performance models, and results related to this study are shared publicly.","Aircraft performance; Drag polar; Aerodynamic coefficient; Bayesian computing; MCMC; Stochastic total energy model","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.","","","","Control & Operations","Control & Simulation","","",""
"uuid:13bb3665-f4b3-4608-8663-671aa764d629","http://resolver.tudelft.nl/uuid:13bb3665-f4b3-4608-8663-671aa764d629","Damage accelerates ice shelf instability and mass loss in Amundsen Sea Embayment","Lhermitte, S.L.M. (TU Delft Mathematical Geodesy and Positioning); Sun, Sainan (Vrije Universiteit Brussel); Shuman, Christopher (NASA Goddard Space Flight Center); Wouters, B. (TU Delft Physical and Space Geodesy; Universiteit Utrecht); Pattyn, Frank (Vrije Universiteit Brussel); Wuite, Jan (ENVEO IT GmbH); Berthier, Etienne (CNES Centre National d'Etudes Spatiales; Université Paul Sabatier; IRD Institut de Recherche pour le Developpement; CNRS); Nagler, Thomas (ENVEO IT GmbH)","","2020","Pine Island Glacier and Thwaites Glacier in the Amundsen Sea Embayment are among the fastest changing outlet glaciers in West Antarctica with large consequences for global sea level. Yet, assessing how much and how fast both glaciers will weaken if these changes continue remains a major uncertainty as many of the processes that control their ice shelf weakening and grounding line retreat are not well understood. Here, we combine multisource satellite imagery with modeling to uncover the rapid development of damage areas in the shear zones of Pine Island and Thwaites ice shelves. These damage areas consist of highly crevassed areas and open fractures and are first signs that the shear zones of both ice shelves have structurally weakened over the past decade. Idealized model results reveal moreover that the damage initiates a feedback process where initial ice shelf weakening triggers the development of damage in their shear zones, which results in further speedup, shearing, and weakening, hence promoting additional damage development. This damage feedback potentially preconditions these ice shelves for disintegration and enhances grounding line retreat. The results of this study suggest that damage feedback processes are key to future ice shelf stability, grounding line retreat, and sea level contributions from Antarctica. Moreover, they underline the need for incorporating these feedback processes, which are currently not accounted for in most ice sheet models, to improve sea level rise projections.","Antarctica; glaciology; ice sheet modeling; remote sensing; sea level rise","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:494e8519-2e5e-4951-bff7-12d8c4888441","http://resolver.tudelft.nl/uuid:494e8519-2e5e-4951-bff7-12d8c4888441","Low power AlGaN/GaN MEMS pressure sensor for high vacuum application","Sun, J. (TU Delft Electronic Components, Technology and Materials; Shenzhen Institute of Wide-bandgap Semiconductors); Hu, D. (TU Delft Electronic Components, Technology and Materials); Liu, Zewen (Tsinghua University); Middelburg, L.M. (TU Delft Electronic Components, Technology and Materials); Vollebregt, S. (TU Delft Electronic Components, Technology and Materials); Sarro, Pasqualina M (TU Delft Electronic Components, Technology and Materials); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2020","A micro-scale pressure sensor based on suspended AlGaN/GaN heterostructure is reported with non-linear sensitivity. By sealing the cavity, vacuum sensing at various temperatures was demonstrated. To validate the proposed concept of the AlGaN/GaN vacuum sensor, a 700 µm diameter circular membrane was electrically characterized under applied static and dynamic pressures at various temperatures ranging from 25 °C to 100 °C. The current change of the AlGaN/GaN heterostructure increased as the vacuum and temperature increases due to the increase of 2DEG density by tensile strain. The dynamic current change from 96 kPa down to 10 Pa of AlGaN/GaN heterostructure pressure sensor was 18.75 % at 100 °C. The maximum sensitivity reached 22.8 %/kPa with a power consumption of 1.8 µW. These results suggest that suspended AlGaN/GaN heterostructures are promising for high vacuum and high-temperature sensing applications.","AlGaN/GaN; MEMS; Pressure sensor; Vacuum","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.","","2021-01-26","","","Electronic Components, Technology and Materials","","",""
"uuid:b7c82d1f-59a8-4bff-bd83-a8c90e7e04b5","http://resolver.tudelft.nl/uuid:b7c82d1f-59a8-4bff-bd83-a8c90e7e04b5","Wave Controls on Deltaic Shoreline‐Channel Morphodynamics: Insights From a Coupled Model","Gao, Weilun (Beijing Normal University; Ministry of Education); Nienhuis, Jaap (Universiteit Utrecht); Nardin, William (University of Maryland Center for Environmental Science); Wang, Zhengbing (TU Delft Coastal Engineering; Beijing Normal University; Deltares); Shao, Dongdong (Beijing Normal University; Ministry of Education); Sun, Tao (Beijing Normal University; Ministry of Education); Cui, Baoshan (Beijing Normal University; Ministry of Education)","","2020","It is widely recognized that waves inhibit river mouth progradation and reduce the avulsion
timescale of deltaic channels. Nevertheless, those effects may not apply to downdrift‐deflected channels. In this study, we developed a coupled model to explore the effects of wave climate asymmetry and alongshore sediment bypassing on shoreline‐channel morphodynamics. The shoreline position and channel trajectory are simulated using a “shoreline” module which drives the evolution of the river profile in a “channel” module by updating the position of river mouth boundary, whereas the channel module provides the sediment load to river mouth for the “shoreline” module. The numerical results show that regional alongshore sediment transport driven by an asymmetric wave climate can enhance the progradation of deltaic channels if sediment bypassing of the river mouth is limited, which is different from the common assumption that waves inhibit delta progradation. As such, waves can have a trade‐off effect on river mouth progradation that can further influence riverbed aggradation and channel avulsion. This trade‐off effect of waves is dictated by the net alongshore sediment transport, sediment bypassing at the river mouth, and wave diffusivity. Based on the numerical results, we further propose a dimensionless parameter that includes fluvial and alongshore sediment supply relative to wave diffusivity to predict the progradation and aggradation rates and avulsion timescale of deltaic channels. The improved understanding of progradation, aggradation, and avulsion timescale of deltaic channels has important implications for
engineering and predicting deltaic wetland creation, particularly under changing water and sediment input to deltaic systems.","","en","journal article","","","","","","","","2021-02-03","","","Coastal Engineering","","",""
"uuid:fd9913cb-7041-4606-a150-1eb073021de2","http://resolver.tudelft.nl/uuid:fd9913cb-7041-4606-a150-1eb073021de2","Analyzing Aircraft Surveillance Signal Quality at the 1090 Megahertz Radio Frequency","Sun, Junzi (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Operations)","","2020","Due to the increasing demands for real-time air traffic monitoring, the 1090 megahertz radio frequency has become the most utilized communication channel for aircraft surveillance purposes. Several services are using the radio frequency at the same time, which are Mode A/C communications and Mode S communications. These different types of communications are not coordinated, meaning that the quality of a communication channel can deteriorate with the increasing number of aircraft in the airspace. This deterioration may further worsen with the increasing number of aircraft that comply with the Automatic Dependent Surveillance-Broadcast requirement, which is implemented based on Mode S Extended Squitter. In this paper, we conduct experiments to determine the quality of 1090 megahertz radio frequency by analyzing the low-level signals using an open-source software-defined radio. First, we implement the demodulation of Mode A/C and Mode S signals from the raw in-phase and quadrature signals with a high sampling rate. Then, several methods are employed to study the occupancy of the communication channel and the garbling severity of the signals, as well as the error rate in ADS-B signals. All results show that the radio frequency is experiencing high communication load during day time air traffic operations. The results also suggest a need for a major redesign of the aircraft surveillance system in the future due to the current inefficient utilization of this radio frequency.","Aircraft surveillance; Communication; ADS-B; Signal analysis; Signal quality; Mode S; 1090 megahertz","en","conference paper","","","","","","Virtual/online event due to COVID-19","","","","Control & Operations","Control & Simulation","","",""
"uuid:ee710182-31bf-495c-ab75-03d37e2742fc","http://resolver.tudelft.nl/uuid:ee710182-31bf-495c-ab75-03d37e2742fc","Mode S Transponder Comm-B Capabilities in Current Operational Aircraft","Sun, Junzi (TU Delft Control & Simulation); Vû, Huy (Air Traffic Control The Netherlands); Olive, Xavier (Université de Toulouse); Hoekstra, J.M. (TU Delft Control & Operations)","","2020","Mode S surveillance allows air traffic controllers to interrogate certain information from aircraft, such as airspeeds, turn parameters, target altitudes, and meteorological conditions. However, not all aircraft have enabled the same capabilities. Before performing any specific interrogation, the surveillance radar must acquire the transponder capabilities of an aircraft. This is obtained via the common usage Ground-initiated Comm-B (GICB) capabilities report (BDS 1,7). With this report, third-party researchers can further improve the identification accuracy of different Mode S Comm-B message types, as well as study the compliance of surveillance standards. Thanks to the OpenSky network’s large-scale global coverage, a full picture of current Mode S capabilities over the world can be constructed. In this paper, using the OpenSky Impala data interface, we first sample over one month of raw BDS 1,7 messages from around the world. Around 40 million messages are obtained. We then decode and analyze the GICB capability messages. The resulting data contain Comm-B capabilities for all aircraft available to OpenSky during this month. The analyses in this paper focus on exploring statistics of GICB capabilities among all aircraft and within each aircraft type. The resulting GICB capability database is shared as an open dataset.","OpenSky; Mode S; GICB; transponder capability; Comm-B","en","journal article","","","","","","","","","","Control & Operations","Control & Simulation","","",""
"uuid:3452a1f9-4cc4-4279-b97c-8cfc6e9e9d42","http://resolver.tudelft.nl/uuid:3452a1f9-4cc4-4279-b97c-8cfc6e9e9d42","Detecting and Measuring Turbulence from Mode S Surveillance Downlink Data","Olive, Xavier (Université de Toulouse); Sun, Junzi (TU Delft Control & Simulation)","","2020","Instability in the movement of air masses in the atmosphere can result in turbulence. Most often, turbulence causes discomfort to passengers but it can occasionally affect their safety as well. Turbulence experienced by aircraft can be difficult to predict, especially for clear air turbulence (CAT) which occurs in the absence of any visual clues. Pilots may report turbulence when they fly through turbulent areas; their input contributes to the issuance of weather advisories (SIGMETs) that contain meteorological information concerning the safety of all aircraft. This paper presents a novel method to detect turbulence experienced by aircraft based on Mode S data, emitted by transponders in reply to BDS 6,0 requests (heading and speed reports) sent by Secondary Surveillance Radars. The method is first validated on a few flights labelled manually by the authors flying around Europe. Then, a large-scale reconstitution of turbulent areas over Europe on ten days across different seasons in 2018 is compared with SIGMETs emitted during the same time interval. This method may be an encouraging entry point for Air Navigation Service Providers so as to gain a better awareness of the turbulence situation, by simply requesting this type of information from aircraft flying in their airspace.","aircraft trajectory; turbulence; ADS-B; Mode S; data analysis","en","conference paper","","","","","","Virtual/online event due to COVID-19","","","","","Control & Simulation","","",""
"uuid:3e2517db-4706-4869-9ae9-05e0f7cb6081","http://resolver.tudelft.nl/uuid:3e2517db-4706-4869-9ae9-05e0f7cb6081","Detecting Events in Aircraft Trajectories: Rule-Based and Data-Driven Approaches","Olive, Xavier (Université de Toulouse); Sun, Junzi (TU Delft Control & Simulation); Lafage, Adrien (Université de Toulouse); Basora, Luis (Université de Toulouse)","","2020","The large amount of aircraft trajectory data publicly available through open data sources like the OpenSky Network presents a wide range of possibilities for monitoring and post-operational analysis of air traffic performance. This contribution addresses the automatic identification of operational events associated with trajectories. This is a challenging task that can be tackled with both empirical, rule-based methods and statistical, data-driven approaches. In this paper, we first propose a taxonomy of significant events, including usual operations such as take-off, Instrument Landing System (ILS) landing and holding, as well as less usual operations like firefighting, in-flight refuelling and navigational calibration. Then, we introduce different rule-based and statistical methods for detecting a selection of these events. The goal is to compare candidate methods and to determine which of the approaches performs better in each situation.","aircraft trajectories; anomaly detection; ADS-B; pattern detection","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:a3271ee7-df7b-46af-a09c-5a2288fd563f","http://resolver.tudelft.nl/uuid:a3271ee7-df7b-46af-a09c-5a2288fd563f","Incremental Nonlinear Fault-Tolerant Control of a Quadrotor With Complete Loss of Two Opposing Rotors","Sun, Sihao (Student TU Delft); Wang, Xuerui (TU Delft Aerospace Structures & Computational Mechanics); Chu, Q. P. (TU Delft Control & Simulation); de Visser, C.C. (TU Delft Control & Simulation)","","2020","In order to further expand the flight envelope of quadrotors under actuator failures, we design a nonlinear sensor-based fault-tolerant controller to stabilize a quadrotor with failure of two opposing rotors in the high-speed flight condition (>8 m/s). The incremental nonlinear dynamic inversion approach which excels in handling model uncertainties is adopted to compensate for the significant unknown aerodynamic effects. The internal dynamics of such an underactuated system have been analyzed, and subsequently stabilized by redefining the control output. The proposed method can be generalized to control a quadrotor under single-rotor-failure and nominal conditions. For validation, flight tests have been carried out in a large-scale open jet wind tunnel. The position of a damaged quadrotor can be controlled in the presence of significant wind disturbances. A linear quadratic regulator approach from the literature has been compared to demonstrate the advantages of the proposed nonlinear method in the windy and high-speed flight condition.","Air safety; fault tolerant control; nonlinear control systems; unmanned aerial vehicles; Uncertainty; Attitude control; Atmospheric modeling; Rotors; Aerodynamics; Robustness; Nonlinear dynamical systems","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.","","2022-01-05","","","Aerospace Structures & Computational Mechanics","","",""
"uuid:d4ebecde-5ecd-4239-ad9f-f43d1f80d452","http://resolver.tudelft.nl/uuid:d4ebecde-5ecd-4239-ad9f-f43d1f80d452","A parameter back-calculation technique for pavements under moving loads","Sun, Z. (TU Delft Pavement Engineering); Kasbergen, C. (TU Delft Pavement Engineering); van Dalen, K.N. (TU Delft Dynamics of Structures); Anupam, K. (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology)","Anupam, Kumar (editor); Papagiannakis, Tom (editor); Bhasin, Amit (editor); Little, Dallas (editor)","2020","Maintenance and rehabilitation strategies of pavements are usually made based on the results of performance evaluation. An efficient tool for pavement structural evaluation at network level is the traffic speed deflectometer (TSD) test. In order to deal with TSD measurements, this paper proposes a parameter back-calculation technique. Firstly, the sensitivity of the surface response for an elastic pavement structure with hysteretic damping to different structural parameters is investigated. Then, the ability of the parameter backcalculation technique is verified by conducting a case study. The results show that the proposed technique is able to back-calculate the structural parameters of pavements by analysing TSD measurements. The presented work contributes to the development of parameter back-calculation techniques for the TSD test.","Parameter back-calculation; Pavement; Moving load; Spectral element method; Traffic speed deflectometer","en","conference paper","CRC Press / Balkema - Taylor & Francis Group","","","","","Accepted author manuscript","","2021-12-08","","","Pavement Engineering","","",""
"uuid:4ef2a27b-5668-4242-8757-e1416de4aaf0","http://resolver.tudelft.nl/uuid:4ef2a27b-5668-4242-8757-e1416de4aaf0","Design exploration of quantitative performance and geometry typology for indoor arena based on self-organizing map and multi-layered perceptron neural network","Pan, W. (TU Delft Design Informatics; South China University of Technology); Sun, Y. (TU Delft Spatial Planning and Strategy; South China University of Technology); Turrin, M. (TU Delft Design Informatics); Louter, P.C. (Technische Universität Dresden); Sariyildiz, I.S. (TU Delft Design Informatics)","","2020","During the early design process, simulations allow numeric assessment and 3D models allow visual inspection for qualitative criteria. However, exploring different design alternatives based on both is challenging. To support the design exploration of quantitative performance and geometry typology of various design alternatives during the early design stages of indoor arenas, this paper proposed a novel design method of SOM-MLPNN by combing self-organizing map (SOM) and multi-layer perceptron neural network (MLPNN), based on the inspiration of local linear mapping based on self-organizing map (SOM-LLM). In SOM-LLM or SOM-MLPNN, the SOM can support designers to explore the whole design space according to geometry typologies and provides reference/labelled inputs for LLM/MLPNN to approximate multiple quantitative performance data for various design alternatives. Both SOM-LLM and SOM-MLPNN are applied and compared in a design of indoor arena. Besides the development of the method, original contributions include 1) proposing two operations (using a large size of SOM network and using a small amount of input data to train the SOM network) to save the computational time and increase the accuracy in data approximation and 2) proposing a series of data visualizations to interpret the results and support design explorations in different ways.","Complex indoor arena; Comprehensive design exploration; SOM-LLM (local linear mapping based on self-organizing map); SOM-MLPNN (multi-layer perceptron neural network based on self-organizing map)","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.","","2020-10-02","","","Design Informatics","","",""
"uuid:955bbe54-a870-4f45-8a19-ae330c446224","http://resolver.tudelft.nl/uuid:955bbe54-a870-4f45-8a19-ae330c446224","Dynamic and interactive re-formulation of multi-objective optimization problems for conceptual architectural design exploration","Yang, D. (TU Delft Design Informatics; South China University of Technology); Di Stefano, Danilo (ESTECO SpA); Turrin, M. (TU Delft Design Informatics); Sariyildiz, I.S. (TU Delft Design Informatics); Sun, Yimin (South China University of Technology)","","2020","Simulation-Based Multi-Objective Optimization (SBMOO) methods are being increasingly used in conceptual architectural design. They mostly focus on the solving, rather than the re-formulation, of a Multi-Objective Optimization (MOO) problem. However, Optimization Problem Re-Formulation (Re-OPF) is necessary for treating ill-defined conceptual architectural design as an iterative exploration process. The paper proposes an innovative SBMOO method which builds in a dynamic and interactive Re-OPF phase. This Re-OPF phase, as the main novelty of the proposed method, aims at achieving a realistic MOO model (i.e., a parametric geometry-simulation model which includes important objectives, constraints, and design variables). The proposed method is applied to the conceptual design of a top-daylighting system, focusing on divergent concept generation. The integration of software tools Grasshopper and modeFRONTIER is adopted to support this application. The main finding from this application is that the proposed method can help to achieve quantitatively better and qualitatively more diverse Pareto solutions.","Conceptual architectural design; Divergent concept generation; GH-MF integration; Hierarchical clustering; Hierarchical variable structure; Information and knowledge extraction; Optimization problem re-formulation; Self-organizing map; Simulation-based multi-objective optimization; Top-daylighting system","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.","","2021-01-01","","","Design Informatics","","",""
"uuid:95a793f0-97a2-4c3f-973b-bf03a2333d8f","http://resolver.tudelft.nl/uuid:95a793f0-97a2-4c3f-973b-bf03a2333d8f","A high responsivity and controllable recovery ultraviolet detector based on a WO3gate AlGaN/GaN heterostructure with an integrated micro-heater","Sun, J. (TU Delft Electronic Components, Technology and Materials); Zhang, Shuo (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Zhan, Teng (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Liu, Zewen (Tsinghua University); Wang, Junxi (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Yi, Xiaoyan (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Li, Jinmin (Chinese Academy of Sciences; University of Chinese Academy of Sciences); Sarro, Pasqualina M (TU Delft Electronic Components, Technology and Materials); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials; Shenzhen Institute of Wide-bandgap Semiconductors)","","2020","A high responsivity and controllable recovery ultraviolet (UV) photodetector based on a tungsten oxide (WO3) gate AlGaN/GaN heterostructure with an integrated micro-heater is reported for the first time. The WO3nanolayer was deposited by physical vapor deposition (PVD) for deep UV absorption and the micro-heater was integrated for chip level heating and cooling. Our device when exposed to UV wavelength exhibits a high responsivity of 1.67 × 104A W−1at 240 nm and a sharp cut-off wavelength of 275 nm. More importantly, the persistent photoconductivity (PPC) effect can be eliminated by a novel method, mono-pulse heating reset (MHR), which consists in applying an appropriate pulse voltage to the micro-heater right after the removal of the UV illumination. The recovery time was reduced from hours to just seconds without reducing the high responsivity and stability of the photodetector. The UV detection, high responsivity, high stability, controllable recovery process and low production cost of GaN-based photodetectors make these devices extremely attractive for several applications, such as fire detection and missile and rocket warning.","","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.","","2021-07-28","","","Electronic Components, Technology and Materials","","",""
"uuid:e0a4f1dd-2798-442c-b5c1-e139b49321ac","http://resolver.tudelft.nl/uuid:e0a4f1dd-2798-442c-b5c1-e139b49321ac","Optimization of mesa etch for a quasi-vertical gan schottky barrier diode (Sbd) by inductively coupled plasma (icp) and device characteristics","Sun, Y. (TU Delft Electronic Components, Technology and Materials; Shenzhen Institute of Wide-bandgap Semiconductors; Chinese Academy of Sciences); Kang, Xuanwu (Chinese Academy of Sciences); Zheng, Yingkui (Chinese Academy of Sciences); Wei, Ke (Chinese Academy of Sciences); Li, Pengfei (Chinese Academy of Sciences); Wang, Wenbo (Shenzhen Institute of Wide-bandgap Semiconductors); Liu, Xinyu (Chinese Academy of Sciences); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2020","The optimization of mesa etch for a quasi-vertical gallium nitride (GaN) Schottky barrier diode (SBD) by inductively coupled plasma (ICP) etching was comprehensively investigated in this work, including selection of the etching mask, ICP power, radio frequency (RF) power, ratio of mixed gas, flow rate, and chamber pressure, etc. In particular, the microtrench at the bottom corner of the mesa sidewall was eliminated by a combination of ICP dry etching and tetramethylammonium hydroxide (TMAH) wet treatment. Finally, a highly anisotropic profile of the mesa sidewall was realized by using the optimized etch recipe, and a quasi-vertical GaN SBD was demonstrated, achieving a low reverse current density of 10−8 A/cm2 at −10 V.","Dry etch; GaN; Inductively coupled plasma (ICP); Mesa; Quasi-vertical; Schottky barrier diode (SBD); Sidewall profile","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:6e97a477-3a0c-43bb-8c75-9e628c071962","http://resolver.tudelft.nl/uuid:6e97a477-3a0c-43bb-8c75-9e628c071962","Markov-based solution for information diffusion on adaptive social networks","Liu, Chuang (Hangzhou Normal University); Zhou, Nan (Hangzhou Normal University); Zhan, X. (TU Delft Multimedia Computing); Sun, Gui-Quan (Shanxi University; North University of China); Zhang, Zi-Ke (Shanxi University; Hangzhou Normal University)","","2020","There is currently growing interest in modeling the information diffusion on social networks across multi-disciplines, including the prediction of the news popularity, the detection of the rumors and the influence of the epidemiological studies. Following the framework of the epidemic spreading, the information spreading models assume that information can be transmitted from the known individuals (infected) to the un-known individuals (susceptible) through the network interactions. During this process, individuals also always change their interactions which in turn will greatly influence the information spreading. In this work, we propose a mechanism considering the co-evolution between information states and network topology simultaneously, in which the information diffusion was executed as an SIS process and network topology evolved based on the adaptive assumption. The theoretical analyses based on the Markov approach were very consistent with simulation. Both simulation results and theoretical analyses indicated that the adaptive process, in which informed individuals would rewire the links between the informed neighbors to a random non-neighbor node, can enhance information diffusion (leading to much broader spreading). In addition, we obtained that two threshold values exist for the information diffusion on adaptive networks, i.e., if the information propagation probability is less than the first threshold, information cannot diffuse and dies out immediately; if the propagation probability is between the first and second threshold, information will spread to a finite range and die out gradually; and if the propagation probability is larger than the second threshold, information will diffuse to a certain size of population in the network. These results may shed some light on understanding the co-evolution between information diffusion and network topology.","Adaptive social networks; Co-evolution; Information spreading","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.","","2020-11-01","","","Multimedia Computing","","",""
"uuid:437dbafd-1869-442d-85d7-04f1124f5e14","http://resolver.tudelft.nl/uuid:437dbafd-1869-442d-85d7-04f1124f5e14","A genetic interaction map centered on cohesin reveals auxiliary factors involved in sister chromatid cohesion in S. Cerevisiae","Sun, Su Ming (Leiden University Medical Center); Batté, Amandine (Leiden University Medical Center); Elmer, Mireille (TU Delft Quantum & Computer Engineering; Leiden University Medical Center); van der Horst, Sophie C. (Leiden University Medical Center); van Welsem, Tibor (Netherlands Cancer Institute); Bean, Gordon (University of California); Ideker, Trey (University of California; Moores UCSD Cancer Center); van Leeuwen, Fred (Netherlands Cancer Institute); van Attikum, Haico (Leiden University Medical Center)","","2020","Eukaryotic chromosomes are replicated in interphase and the two newly duplicated sister chromatids are held together by the cohesin complex and several cohesin auxiliary factors. Sister chromatid cohesion is essential for accurate chromosome segregation during mitosis, yet has also been implicated in other processes, including DNA damage repair, transcription and DNA replication. To assess how cohesin and associated factors functionally interconnect and coordinate with other cellular processes, we systematically mapped the genetic interactions of 17 cohesin genes centered on quantitative growth measurements of >52,000 gene pairs in the budding yeast Saccharomyces cerevisiae. Integration of synthetic genetic interactions unveiled a cohesin functional map that constitutes 373 genetic interactions, revealing novel functional connections with post-replication repair, microtubule organization and protein folding. Accordingly, we show that the microtubule-associated protein Irc15 and the prefoldin complex members Gim3, Gim4 and Yke2 are new factors involved in sister chromatid cohesion. Our genetic interaction map thus provides a unique resource for further identification and functional interrogation of cohesin proteins. Since mutations in cohesin proteins have been associated with cohesinopathies and cancer, it may also help in identifying cohesin interactions relevant in disease etiology.","Cohesin; Cohesinopathy; Genetic interaction mapping; Irc15; Prefoldin; Sister chromatid cohesion","en","journal article","","","","","","","","","","Quantum & Computer Engineering","","","",""
"uuid:d904b912-d8d3-4730-923e-08807b410255","http://resolver.tudelft.nl/uuid:d904b912-d8d3-4730-923e-08807b410255","OpenAP: An open-source aircraft performance model for air transportation studies and simulations","Sun, Junzi (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Operations); Ellerbroek, Joost (TU Delft Control & Simulation)","","2020","Air traffic simulations serve as common practice to evaluate different concepts and methods for air transportation studies. The aircraft performance model is a key element that supports these simulation-based studies. It is also an important component for simulation-independent studies, such as air traffic optimization and prediction studies. Commonly, contemporary studies have to rely on proprietary aircraft performance models that restrict the redistribution of the data and code. To promote openness and research comparability, an alternative open performance model would be beneficial for the air transportation research community. In this paper, we introduce an open aircraft performance model (OpenAP). It is an open-source model that is based on a number of our previous studies, which were focused on different components of the aircraft performance. The unique characteristic of OpenAP is that it was built upon open aircraft surveillance data and open literature models. The model is composed of four main components, including aircraft and engine properties, kinematic performances, dynamic performances, and utility libraries. Alongside the performance model, we are publishing an open-source toolkit to facilitate the use of this model. The main objective of this paper is to describe each main component, their connections, and how they can be used for simulation and research in practice. Finally, we analyzed the performance of OpenAP by comparing it with an existing performance model and sample flight data.","Aircraft performance; Drag polar model; Fuel flow model; Kinematic model; OpenAP; Thrust model","en","journal article","","","","","","","","","","Control & Operations","Control & Simulation","","",""
"uuid:ea5a95ef-e48e-4d9a-8fb6-c3edb14d6dbe","http://resolver.tudelft.nl/uuid:ea5a95ef-e48e-4d9a-8fb6-c3edb14d6dbe","A nonlinear spectral element model for the simulation of traffic speed deflectometer tests of asphalt pavements","Sun, Z. (TU Delft Pavement Engineering); Kasbergen, C. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology); van Dalen, K.N. (TU Delft Dynamics of Structures); Anupam, K. (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering)","","2020","A non-destructive testing method suitable for network-level pavement structural evaluation is the traffic speed deflectometer (TSD) test. However, the analysis of TSD measurements still needs a proper parameter back-calculation procedure, which requires an accurate and efficient forward calculation model. As a first step to solving this issue, a nonlinear spectral element model which can simulate TSD tests of asphalt pavements is developed. The model is used to investigate the characteristics and parameter sensitivity of the response of asphalt pavements caused by the TSD loading. The results indicate that the vertical deflection curve along the direction of movement observed on the asphalt pavement surface is slightly asymmetric, and the maximum deflection appears behind the centre of the loading area. In addition, the slope curve of vertical deflection is highly sensitive to the magnitude of the applied force, the moduli of the base layer and subgrade, and the thicknesses of the asphalt layer and base layer. Furthermore, the slope curve is relatively sensitive to the glassy modulus of the asphalt layer. Because of its good predictive capability and high computational efficiency, the proposed model has the desired characteristics to be used as the computational kernel for parameter back-calculation procedures of TSD measurements.","Asphalt pavement; dynamic model; moving load; spectral element method; traffic speed deflectometer","en","journal article","","","","","","","","","","","Pavement Engineering","","",""
"uuid:dbfe6d5a-b16b-4d34-ad78-6b0082e3e1a4","http://resolver.tudelft.nl/uuid:dbfe6d5a-b16b-4d34-ad78-6b0082e3e1a4","A review on the pumping behavior of modern concrete","Li, Huajian (Railway Engineering Research Institute); Sun, Deyi (Railway Engineering Research Institute); Wang, Zhen (Railway Engineering Research Institute); Huang, Fali (Railway Engineering Research Institute); Yi, Zhonglai (Railway Engineering Research Institute); Yang, Zhengxian (Fuzhou University); Zhang, Y. (TU Delft Materials and Environment; Fuzhou University)","","2020","Pumping is the most common technique used to transport fresh concrete in construction sites. The large-scale use of concrete all over the world makes the pumping increasingly important. A wide variety of additives and admixtures are incorporated into modern concrete in order for sustainable development. The performance of modern concrete is rather complex and its pumping behavior differs significantly from that of conventional concrete, especially in the fresh stage. This paper presents a comprehensive overview on the state of the art of concrete pumping. The models and methods used for characterizing the concrete pumpability and lubrication layer are described. The factors influencing the pumping behavior are discussed. A couple of ultra-high pumping engineering of concrete conducted in China are introduced.","","en","journal article","","","","","","Accepted Author Manuscript","","","","","Materials and Environment","","",""
"uuid:0cf3c655-8ece-46bf-a281-ff1a90ca5c1e","http://resolver.tudelft.nl/uuid:0cf3c655-8ece-46bf-a281-ff1a90ca5c1e","Multiple linear regression and thermodynamic fluctuations are equivalent for computing thermodynamic derivatives from molecular simulation","Rahbari, A. (TU Delft Engineering Thermodynamics); Josephson, Tyler R. (University of Minnesota Twin Cities; University of Minnesota); Sun, Yangzesheng (University of Minnesota); Moultos, O. (TU Delft Engineering Thermodynamics); Dubbeldam, D. (Universiteit van Amsterdam); Siepmann, J. Ilja (University of Minnesota); Vlugt, T.J.H. (TU Delft Engineering Thermodynamics)","","2020","Partial molar properties are of fundamental importance for understanding properties of non-ideal mixtures. Josephson and co-workers (Mol. Phys. 2019, 117, 3589–3602) used least squares multiple linear regression to obtain partial molar properties in open constant-pressure ensembles. Assuming composition-independent partial molar properties for the narrow composition range encountered throughout simulation trajectories, we rigorously prove the equivalence of two approaches for computing thermodynamic derivatives in open ensembles of an n-component system: (1) multiple linear regression, and (2) thermodynamic fluctuations. Multiple linear regression provides a conceptually simple and computationally efficient way of computing thermodynamic derivatives for multicomponent systems. We show that in the reaction ensemble, the reaction enthalpy can be computed directly by simple multiple linear regression of the enthalpy as a function of the number of reactant molecules. Non-linear regression and a Gaussian process model taking into account the compositional dependence of partial molar properties further support that multiple linear regression captures the correct physics.","Linear regression; Molecular simulation; Open ensembles thermodynamic fluctuations; Partial molar properties","en","journal article","","","","","","","","","","","Engineering Thermodynamics","","",""
"uuid:f66b2cbb-10e2-4023-84b4-86986e3a0259","http://resolver.tudelft.nl/uuid:f66b2cbb-10e2-4023-84b4-86986e3a0259","The Practice and Enlightenment of Architectural Renovation and Urban Renewal in the Netherlands","Jing, Liping (Soochow University); Sun, L. (TU Delft History, Form & Aesthetics; Soochow University); Zhu, Fengji (Soochow University)","","2020","With the development of local urban renewal in the Netherlands, Dutch architects as Rem Koolhass, Francine Houben and Kees Kaan, etc. have showed rich practical experiences. As a result, the architectural renovation and urban renewal have presented a thriving scene. In this article, the types of urban renewal in the Netherlands are classified as three main categories: regional renewal, architectural heritage refurbishment, and adaptive reuse [1]. From the perspective of types to strategies, this study analyzes typical cases including the Westerpark West, Speelhuis theater, Timmerhuis and Villa Industria and so on, exploring the role of Dutch architects, the method of transformation and sustainable meaning of urban renewal. The research tries to summarize the Dutch mode and experiences, providing a new perspective and methodology for relevant transformation practices of urban renewal in China.","","en","journal article","","","","","","","","","","","History, Form & Aesthetics","","",""
"uuid:0dc7b3c0-e463-4789-bd7b-4f4ebb453716","http://resolver.tudelft.nl/uuid:0dc7b3c0-e463-4789-bd7b-4f4ebb453716","Material-structure integrated design optimization of GFRP bridge deck on steel girder","Xin, H. (TU Delft Steel & Composite Structures; Xi’an Jiaotong University; Tongji University); Mosallam, Ayman (University of California); Correia, José A.F.O. (INEGI); Liu, Yuqing (Tongji University); He, Jun (Changsha University of Science and Technology; Heriot-Watt University); Sun, Yun (Tongji University)","","2020","Design optimization of fiber-reinforced polymeric (FRP) composite products is essential to facilitate their applications in engineering structures. For bridge structures, the main design optimization goals are the reduction of FRP material consumption and the structure weight, which aim to reduce the initial construction cost and achieve a longer bridge span. Compared with conventional steel–concrete composite bridges, FRP-steel composite bridges possess more design variables and more complex design process, which necessitate the simplified optimization models. This paper aims to propose a two-scale design optimation method for FRP bridge deck on the steel girder. The macro behavior of the pultruded FRP composite bridge deck is analyzed. Regarding the micro level, the equivalent properties of pultruded GFRP lamination are calculated by combining micromechanics and classical lamination theory (CLT). The above-mentioned macro pultruded GFRP bridge level and the micro fiber/resin level were bridged based on the assumption that the micro-component effective homogenized strain equals to the corresponding macro strain. The two-scale lamination optimization of pultruded GFRP bridge deck is finally achieved by finding optimized two-scale design variables that can achieve the minimum bridge weight or the lowest initial construction cost with all listed constraint requirements satisfied. A pultruded FRP deck supported on equally-spaced steel girders was selected as a case study to show how to obtain the optimized two-scale parameters by using this proposed optimization method. The optimized results of the top flange thickness, tu, the bottom flange thickness, tl, the web height, hw, and the web thickness per meter, tw, are 46.02 mm, 45.86 mm, 300.0 mm and 37.42 mm, respectively. Results also showed that the optimized ratio of the 0°-lamina, 45°-lamina, and the 90°-lamina are77.9%, 17.1%, 5.0%. The optimized fiber volume fraction is 65.2%.","Composite bridge girder; Laminations; Multiscale optimization; Pultruded GFRP bridge deck","en","journal article","","","","","","Accepted Author Manuscript","","2021-07-24","","","Steel & Composite Structures","","",""
"uuid:3bbbe733-0ebf-4164-9710-51cf85720e78","http://resolver.tudelft.nl/uuid:3bbbe733-0ebf-4164-9710-51cf85720e78","Current challenges and opportunities in microstructure-related properties of advanced high-strength steels","Raabe, Dierk (Max-Planck-Institut für Eisenforschung); Sun, Binhan (Max-Planck-Institut für Eisenforschung); Kwiatkowski Da Silva, Alisson (Max-Planck-Institut für Eisenforschung); Gault, Baptiste (Max-Planck-Institut für Eisenforschung; Imperial College London); Yen, Hung Wei (National Taiwan University); Sedighiani, K. (TU Delft (OLD) MSE-3; Max-Planck-Institut für Eisenforschung); Thoudden Sukumar, Prithiv (Max-Planck-Institut für Eisenforschung); Souza Filho, Isnaldi R. (Max-Planck-Institut für Eisenforschung); Katnagallu, Shyam (Max-Planck-Institut für Eisenforschung; Karlsruhe Institut für Technologie); Jägle, Eric (Max-Planck-Institut für Eisenforschung; University of the Federal Armed Forces Munich); Kürnsteiner, Philipp (Max-Planck-Institut für Eisenforschung); Kusampudi, Navyanth (Max-Planck-Institut für Eisenforschung); Stephenson, Leigh (Max-Planck-Institut für Eisenforschung); Herbig, Michael (Max-Planck-Institut für Eisenforschung); Liebscher, Christian H. (Max-Planck-Institut für Eisenforschung); Springer, Hauke (Max-Planck-Institut für Eisenforschung; Rheinisch-Westfälische Technische Hochschule); Zaefferer, Stefan (Max-Planck-Institut für Eisenforschung); Shah, Vitesh (Max-Planck-Institut für Eisenforschung); Wong, Su Leen (Max-Planck-Institut für Eisenforschung); Baron, Christian (Max-Planck-Institut für Eisenforschung); Diehl, Martin (Max-Planck-Institut für Eisenforschung); Roters, Franz (Max-Planck-Institut für Eisenforschung); Ponge, Dirk (Max-Planck-Institut für Eisenforschung)","","2020","This is a viewpoint paper on recent progress in the understanding of the microstructure–property relations of advanced high-strength steels (AHSS). These alloys constitute a class of high-strength, formable steels that are designed mainly as sheet products for the transportation sector. AHSS have often very complex and hierarchical microstructures consisting of ferrite, austenite, bainite, or martensite matrix or of duplex or even multiphase mixtures of these constituents, sometimes enriched with precipitates. This complexity makes it challenging to establish reliable and mechanism-based microstructure–property relationships. A number of excellent studies already exist about the different types of AHSS (such as dual-phase steels, complex phase steels, transformation-induced plasticity steels, twinning-induced plasticity steels, bainitic steels, quenching and partitioning steels, press hardening steels, etc.) and several overviews appeared in which their engineering features related to mechanical properties and forming were discussed. This article reviews recent progress in the understanding of microstructures and alloy design in this field, placing particular attention on the deformation and strain hardening mechanisms of Mn-containing steels that utilize complex dislocation substructures, nanoscale precipitation patterns, deformation-driven transformation, and twinning effects. Recent developments on microalloyed nanoprecipitation hardened and press hardening steels are also reviewed. Besides providing a critical discussion of their microstructures and properties, vital features such as their resistance to hydrogen embrittlement and damage formation are also evaluated. We also present latest progress in advanced characterization and modeling techniques applied to AHSS. Finally, emerging topics such as machine learning, through-process simulation, and additive manufacturing of AHSS are discussed. The aim of this viewpoint is to identify similarities in the deformation and damage mechanisms among these various types of advanced steels and to use these observations for their further development and maturation.","","en","journal article","","","","","","","","","","","(OLD) MSE-3","","",""
"uuid:881588cf-b872-4c6d-8735-8083fa1478ff","http://resolver.tudelft.nl/uuid:881588cf-b872-4c6d-8735-8083fa1478ff","An opportunistic maintenance strategy for offshore wind turbine system considering optimal maintenance intervals of subsystems","Li, M. (TU Delft Transport Engineering and Logistics; Harbin Engineering University); Wang, Mian (CSSC Cruise Technology Development); Kang, Jichuan (Harbin Engineering University; Naval Architecture and Offshore Technology); Sun, Liping (Harbin Engineering University); Jin, Peng (Harbin Engineering University)","","2020","Operation and maintenance (O&M) costs account for a large proportion of the total costs for offshore wind energy. Performing a reasonable maintenance strategy is an effective approach to reduce O&M costs and gain more profits. In this paper, an opportunistic maintenance strategy for offshore wind turbine systems considering maintenance intervals of each subsystem is proposed to minimize the total maintenance cost. First, a Non-homogeneous Continuous-Time Markov Process based state transition model is established to study degradation process of subsystems. The influence of maintenance time schedule on the maintenance cost is studied to obtain the optimal maintenance intervals of each subsystems. Then, an opportunistic maintenance model considering economic dependencies between multiple subsystems is proposed to optimize the maintenance strategy by combining maintenance activities of individual subsystems to a grouping maintenance activity. A numerical example is used to indicate the significant effectiveness of the maintenance model. The result shows that the total maintenance cost of an offshore wind turbine system will be reduced by adopting the opportunistic maintenance strategy when compared with conventional preventive maintenance strategy.","Cost-effective maintenance; Maintenance optimization; Offshore wind energy; Operation and maintenance","en","journal article","","","","","","Accepted Author Manuscript","","2022-09-21","","","Transport Engineering and Logistics","","",""
"uuid:e24abfab-0625-48e0-9be4-35d163b30bb3","http://resolver.tudelft.nl/uuid:e24abfab-0625-48e0-9be4-35d163b30bb3","A novel method for joint optimization of the sailing route and speed considering multiple environmental factors for more energy efficient shipping","Wang, K. (TU Delft Transport Engineering and Logistics; Dalian Maritime University); Li, Jiayuan (Dalian Maritime University); Huang, Lianzhong (Dalian Maritime University); Ma, Ranqi (Dalian Maritime University); Jiang, X. (TU Delft Transport Engineering and Logistics); Yuan, Yupeng (MOST; University of Cambridge); Mwero, Ngome A. (Dalian Maritime University); Negenborn, R.R. (TU Delft Transport Engineering and Logistics; MOST); Sun, Peiting (Dalian Maritime University); Yan, Xinping (MOST)","","2020","Energy saving and emission reduction have attracted a great deal of attention in the maritime industry. The optimization of a ship's energy efficiency can reduce energy consumption and CO2 emissions effectively. However, most of the available studies only focus on either the sailing speed or route optimization, and the interaction between speed and route under the influence of multiple environmental factors was not accounted properly. In this paper, a novel joint optimization method of the sailing route and speed, which considers the interaction between route and speed as well as multiple environmental factors, is proposed to fully exploit the energy efficiency's potential. Moreover, a joint optimization model of the sailing route and speed, which is based on an energy consumption model that considers multiple environmental factors, is established. Next, a solution algorithm for the joint optimization model is investigated in order to achieve joint decision-making with regard to the sailing route and speed. Finally, a case study is conducted that demonstrates the effectiveness of the proposed method. The results show that the proposed method can achieve the optimal sailing route and speed under complex environmental conditions, as well as a reduction in fuel consumption and CO2 emissions of about 4%.","CO emission; Energy consumption; Energy system; Route optimization; Speed optimization","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.","","2021-03-02","","","Transport Engineering and Logistics","","",""
"uuid:6ab318cd-fbd3-4748-8555-9ac6c9e295b9","http://resolver.tudelft.nl/uuid:6ab318cd-fbd3-4748-8555-9ac6c9e295b9","Impact of coastal East Antarctic ice rises on surface mass balance: Insights from observations and modeling","Kausch, T. (TU Delft Mathematical Geodesy and Positioning); Lhermitte, S.L.M. (TU Delft Mathematical Geodesy and Positioning); T. M. Lenaerts, Jan (University of Colorado); Wever, Nander (University of Colorado); Inoue, Mana (Vrije Universiteit Brussel); Pattyn, Frank (Vrije Universiteit Brussel); Sun, Sainan (Vrije Universiteit Brussel); Wauthy, Sarah (Vrije Universiteit Brussel); Tison, Jean-Louis (Vrije Universiteit Brussel); Jan Van De Berg, Willem (Universiteit Utrecht)","","2020","About 20 % of all snow accumulation in Antarctica occurs on the ice shelves. There, ice rises control the spatial surface mass balance (SMB) distribution by inducing snowfall variability and wind erosion due to their topography. Moreover these ice rises buttress the ice flow and represent ideal drilling locations for ice cores. In this study we assess the connection between snowfall variability and wind erosion to provide a better understanding of how ice rises impact SMB variability, how well this is captured in the regional atmospheric climate model RACMO2 and the implications of this SMB variability for ice rises as an ice core drilling site. By combining ground-penetrating radar (GPR) profiles from two ice rises in Dronning Maud Land with ice core dating, we reconstruct spatial and temporal SMB variations from 1983 to 2018 and compare the observed SMB with output from RACMO2 and SnowModel. Our results show snowfall-driven differences of up to 1.5 times higher SMB on the windward side of both ice rises than on the leeward side as well as a local erosion-driven minimum at the ice divide of the ice rises. RACMO2 captures the snowfall-driven differences but overestimates their magnitude, whereas the erosion on the peak can be reproduced by SnowModel with RACMO2 forcing. Observed temporal variability of the average SMBs, retrieved from the GPR data for four time intervals in the 1983-2018 range, are low at the peak of the easternmost ice rise (∼ 0.06 m w.e. yr−1), while they are higher (∼ 0.09 m w.e. yr−1) on the windward side of the ice rise. This implies that at the peak of the ice rise, higher snowfall, driven by orographic uplift, is balanced out by local erosion. As a consequence of this, the SMB recovered from the ice core matches the SMB from the GPR at the peak of the ice rise but not at the windward side of the ice rise, suggesting that the SMB signal is damped in the ice core.","","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:2431da73-909f-46a7-b62a-6476ac97577c","http://resolver.tudelft.nl/uuid:2431da73-909f-46a7-b62a-6476ac97577c","Controlled Quantum Dot Formation in Atomically Engineered Graphene Nanoribbon Field-Effect Transistors","El Abbassi, M. (TU Delft QN/van der Zant Lab; University of Basel; Kavli institute of nanoscience Delft; Swiss Federal Laboratories for Materials Science and Technology (Empa)); Perrin, M.L. (Swiss Federal Laboratories for Materials Science and Technology (Empa)); Barin, Gabriela Borin (Swiss Federal Laboratories for Materials Science and Technology (Empa)); Sangtarash, Sara (Lancaster University; University of Warwick); Overbeck, Jan (Swiss Federal Laboratories for Materials Science and Technology (Empa); University of Basel); Braun, Oliver (Swiss Federal Laboratories for Materials Science and Technology (Empa); University of Basel); Lambert, Colin J. (Lancaster University); Sun, Qiang (Swiss Federal Laboratories for Materials Science and Technology (Empa)); Prechtl, Thorsten (Max Planck Institute for Polymer Research)","","2020","Graphene nanoribbons (GNRs) have attracted strong interest from researchers worldwide, as they constitute an emerging class of quantum-designed materials. The major challenges toward their exploitation in electronic applications include reliable contacting, complicated by their small size (<50 nm), and the preservation of their physical properties upon device integration. In this combined experimental and theoretical study, we report on the quantum dot behavior of atomically precise GNRs integrated in a device geometry. The devices consist of a film of aligned five-atom-wide GNRs (5-AGNRs) transferred onto graphene electrodes with a sub 5 nm nanogap. We demonstrate that these narrow-bandgap 5-AGNRs exhibit metal-like behavior at room temperature and single-electron transistor behavior for temperatures below 150 K. By performing spectroscopy of the molecular levels at 13 K, we obtain addition energies in the range of 200-300 meV. DFT calculations predict comparable addition energies and reveal the presence of two electronic states within the bandgap of infinite ribbons when the finite length of the 5-AGNR is accounted for. By demonstrating the preservation of the 5-AGNRs' molecular levels upon device integration, as demonstrated by transport spectroscopy, our study provides a critical step forward in the realization of more exotic GNR-based nanoelectronic devices.","Coulomb blockade; device integration; graphene nanoribbons; molecular spectroscopy; Raman spectroscopy","en","journal article","","","","","","","","","","","QN/van der Zant Lab","","",""
"uuid:3d223258-6a9e-43b4-9db5-615669e7c9e9","http://resolver.tudelft.nl/uuid:3d223258-6a9e-43b4-9db5-615669e7c9e9","动态的遗产策略:文化、经济、历史维度下的荷兰建筑遗产改造实践","Zhu, K. (TU Delft History, Form & Aesthetics); Hein, C.M. (TU Delft History, Form & Aesthetics); Sun, L. (TU Delft History, Form & Aesthetics)","","2020","The dynamic heritage strategy is an era choice to respond to the “modern monument paradox”. As a highly malleable concept, heritage, whether it is the concept itself or its related practices, has to be discussed, and criticized before recognition in a constant movement. The typical Dutch tolerant society has been facing the impact of multiculturalism and the resulting dynamic identity. The national government therefore proposed a sustainable development concept of “conservation through development” for both heritage protection and regional spatial planning. From the perspective of architects, this paper discusses the dynamic strategies in heritage restoration and transformation from three dimensions of culture, economy and history. Focusing on strategies and specific methods, this paper analyses the dynamic Dutch mode and its positive influence on integrated heritage conservation, evoking sustainable strategies for modern heritage transformation of times.","Heritage strategies; Dutch modes; Modern heritage; Integrality; Adaptive reuse; Modern monument paradox","zh","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.","","2021-06-01","","","History, Form & Aesthetics","","",""
"uuid:18fad1de-1320-4a26-b412-f5c17d5ebe18","http://resolver.tudelft.nl/uuid:18fad1de-1320-4a26-b412-f5c17d5ebe18","Robust and automatic data cleansing method for short-term load forecasting of distribution feeders","Huyghues-Beaufond, Nathalie (Imperial College London); Tindemans, Simon H. (TU Delft Intelligent Electrical Power Grids); Falugi, Paola (Imperial College London); Sun, Mingyang (Imperial College London); Strbac, Goran (Imperial College London)","","2020","Distribution networks are undergoing fundamental changes at medium voltage level. To support growing planning and control decision-making, the need for large numbers of short-term load forecasts has emerged. Data-driven modelling of medium voltage feeders can be affected by (1) data quality issues, namely, large gross errors and missing observations (2) the presence of structural breaks in the data due to occasional network reconfiguration and load transfers. The present work investigates and reports on the effects of advanced data cleansing techniques on forecast accuracy. A hybrid framework to detect and remove outliers in large datasets is proposed; this automatic procedure combines the Tukey labelling rule and the binary segmentation algorithm to cleanse data more efficiently, it is fast and easy to implement. Various approaches for missing value imputation are investigated, including unconditional mean, Hot Deck via k-nearest neighbour and Kalman smoothing. A combination of the automatic detection/removal of outliers and the imputation methods mentioned above are implemented to cleanse time series of 342 medium-voltage feeders. A nested rolling-origin-validation technique is used to evaluate the feed-forward deep neural network models. The proposed data cleansing framework efficiently removes outliers from the data, and the accuracy of forecasts is improved. It is found that Hot Deck (k-NN) imputation performs best in balancing the bias-variance trade-off for short-term forecasting.","Binary segmentation; Distribution systems; Kalman smoothing; Multi-step forecasts; Outlier detection","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.","","2020-09-01","","","Intelligent Electrical Power Grids","","",""
"uuid:2b6ba1a5-095b-4f63-86b5-e17644013863","http://resolver.tudelft.nl/uuid:2b6ba1a5-095b-4f63-86b5-e17644013863","Incremental model-based heuristic dynamic programming with output feedback applied to aerospace system identification and control","Sun, B. (TU Delft Control & Simulation); van Kampen, E. (TU Delft Control & Simulation)","","2020","Sufficient information about system dynamics and inner states is often unavailable to aerospace system controllers, which requires model-free and output feedback control techniques, respectively. This paper presents a novel self-learning control algorithm to deal with these two problems by combining the advantages of heuristic dynamic programming and incremental modeling. The system dynamics is completely unknown and only input/output data can be acquired. The controller identifies the local system models and learns control polices online both by tuning the weights of neural networks. The novel method has been applied to a multi-input multi-output nonlinear satellite attitude tracking control problem. The simulation results demonstrate that, compared with the conventional actor-critic-identifier-based heuristic dynamic programming algorithm with three networks, the proposed adaptive control algorithm improves online identification of the nonlinear system with respect to precision and speed of convergence, while maintaining similar performance compared to the full state feedback situation.","","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","","","","","","Control & Simulation","","",""
"uuid:77752baf-b7b5-4836-bfdf-5aeba8d6919e","http://resolver.tudelft.nl/uuid:77752baf-b7b5-4836-bfdf-5aeba8d6919e","Launch vehicle discrete-time optimal tracking control using global dual heuristic programming","Sun, B. (TU Delft Control & Simulation); van Kampen, E. (TU Delft Control & Simulation)","","2020","Optimal tracking is a widely researched control problem, but the unavailability of sufficient information referring to system dynamics brings challenges. In this paper, an optimal tracking control method is proposed for an unknown launch vehicle based on the global dual heuristic programming technique. The nonlinear system dynamics is identified by an offline trained neural network and a feedforward neuro-controller is developed to obtain the desired system input and to facilitate the execution of the feedback controller. By transforming the tracking control problem into a regulation problem, an iterative adaptive dynamic programming algorithm, subject to global dual heuristic programming with explicit analytical calculations, is utilized to deal with the newly built regulation problem. The simulation results demonstrate that the developed method can learn an effective control law for the given optimal tracking control tasks.","","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","","","","","","Control & Simulation","","",""
"uuid:93b461c6-4ce1-4f05-9394-59741bb11b0c","http://resolver.tudelft.nl/uuid:93b461c6-4ce1-4f05-9394-59741bb11b0c","A Pioneering Career in Catalysis: Manfred T. Reetz","Acevedo-Rocha, Carlos G. (Biosyntia ApS, Copenhagen); Hollmann, F. (TU Delft BT/Biocatalysis); Sanchis, Joaquin (Monash University); Sun, Zhoutong (Chinese Academy of Sciences)","","2020","In this invited Account, we highlight the enormous scientific breadth of our mentor Professor Manfred T. Reetz. It stretches from the development of organometallic reagents and transition metal catalysts to the adventurous idea of directed evolution of chemo-, stereo-, and regioselective enzymes, which he considered to be most important. We hope to show that Reetz did not consider these research areas to be totally unrelated realms, and attempt to reveal his transdisciplinary way of thinking about methodology development. Since biocatalysis has become crucial for chemical synthesis, we mainly focus on Reetz's contributions in this area. Some personal reflections from some of his former co-workers are also included, which reveal the stimulating atmosphere in the Reetz group in terms of science, career advice, and the importance of ethical considerations.","biocatalysis; directed evolution; protein engineering; regioselectivity; saturation mutagenesis; stereoselectivity","en","journal article","","","","","","","","","","","BT/Biocatalysis","","",""
"uuid:72ac2f3f-7bc7-4f3c-a582-d0654b1643b6","http://resolver.tudelft.nl/uuid:72ac2f3f-7bc7-4f3c-a582-d0654b1643b6","Composition- and Condition-Dependent Kinetics of Homogeneous Ester Hydrogenation by a Mn-Based Catalyst","Krieger, A.M. (TU Delft ChemE/Inorganic Systems Engineering); Kuliaev, Pavel (ITMO University); Armstrong Hall, Felix Q. (Student TU Delft); Sun, D. (TU Delft ChemE/Inorganic Systems Engineering); Pidko, E.A. (TU Delft ChemE/Algemeen; TU Delft ChemE/Inorganic Systems Engineering; ITMO University)","","2020","The reaction medium and conditions are the key parameters defining the efficiency and performance of a homogeneous catalyst. In the state-of-the-art molecular descriptions of catalytic systems by density functional theory (DFT) calculations, the reaction medium is commonly reduced to an infinitely diluted ideal solution model. In this work, we carry out a detailed operando computational modeling analysis of the condition dependencies and nonideal solution effects on the mechanism and kinetics of a model ester hydrogenation reaction by a homogeneous Mn(I)-P,N catalyst. By combining DFT calculations, COSMO-RS solvent model, and the microkinetic modeling approach, the kinetic behavior of the multicomponent homogeneous catalyst system under realistic reaction conditions was investigated in detail. The effects of the reaction medium and its dynamic evolution in the course of the reaction were analyzed by comparing the results obtained for the model methyl acetate hydrogenation reaction in a THF solution and under solvent-free neat reaction conditions. The dynamic representations of the reaction medium give rise to strongly nonlinear effects in the kinetic models. The nonideal representation of the reaction medium results in pronounced condition dependencies of the computed energetics of the elementary reaction steps and the computed kinetic profiles but affects only slightly such experimentally accessible kinetic descriptors as the apparent activation energy and the degree of rate control.","","en","journal article","","","","","","","","","","","ChemE/Inorganic Systems Engineering","","",""
"uuid:55a16db0-4bda-4d74-8406-cce205c051de","http://resolver.tudelft.nl/uuid:55a16db0-4bda-4d74-8406-cce205c051de","Parameter Identification of Asphalt Pavements Subjected to Moving Loads","Sun, Z. (TU Delft Pavement Engineering); Kasbergen, C. (TU Delft Pavement Engineering); van Dalen, K.N. (TU Delft Dynamics of Structures); Anupam, K. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology); Erkens, S. (TU Delft Pavement Engineering)","Raab, Christiane (editor)","2020","Pavements generally demand necessary maintenance and rehabilitation to maintain their service performance in the whole lifespan. The maintenance and rehabilitation strategies are usually formulated based on the results of non-destructive testing, in which the traffic speed deflectometer (TSD) test is an efficient tool for pavement structural evaluation at network level. In this paper, the TSD test on asphalt pavements is simulated by a spectral element method-based theoretical model, which is further combined with a nonlinear minimisation algorithm to achieve parameter identification. After conducting parameter sensitivity analysis, a case study is used to demonstrate the ability of the proposed parameter identification technique. The results show that this technique is able to deal with TSD measurements to effectively identify the structural parameters of asphalt pavements. The presented TSD test-based parameter identification technique is a promising tool for asphalt pavement structural evaluation at network level, which is beneficial to formulate cost-effective maintenance and rehabilitation strategies.","Parameter identification; Asphalt pavement; Moving load; Spectral element method; Traffic speed deflectometer","en","conference paper","Springer","","","","","Accepted author manuscript","","2021-06-20","","","Pavement Engineering","","",""
"uuid:74cd2af4-a815-467d-b9af-3e221c393047","http://resolver.tudelft.nl/uuid:74cd2af4-a815-467d-b9af-3e221c393047","A novel method to evaluate cleaning quality of oil in shale using pyrolysis pyrogram","Dong, Xu (Qingdao University of Science and Technology); Shen, Luyi (University of Alberta); Zhao, Jianpeng (Xi'an Shiyou University); Liu, Xuefeng (China University of Science and Technology); Sun, Yuli (Qingdao University of Science and Technology); Golsanami, Naser (Shandong University of Science and Technology); Wang, Fei (Qingdao University of Science and Technology); Bi, Haisheng (Qingdao University of Science and Technology); Zitha, P.L.J. (TU Delft Reservoir Engineering; Qingdao University of Science and Technology)","","2020","Complete and thorough core cleaning is a critical prerequisite for the precise measurements of most rock's petrophysical parameters. In shale, the oil cleaning process, aimed to remove the volatile hydrocarbons, is often complicated by the requirement for intact solid organic. Evaluation of shale's cleaning methods needs to take structural integrity of organic matrix into account but neglected in the existing researches. Here, we develop a novel evaluation method using a modified ESH (extended slow heating) pyrolysis cycle, which starts at a lower initial temperature of 150°C for 10 minutes and then slowly increases to 650°C by 10°C/min. Hydrocarbons on the ESH pyrogram were divided into light free hydrocarbon (SA), FHR (fluid-like hydrocarbon, SB), and solid organic matter (SC). We propose a set of quantitative evaluation criterions comparing the results of pyrograms, for different types of the hydrocarbons, at different cleaning conditions. We showed that a modified pyrogram achieves complete cleaning with SA and SB removed while SC remains almost intact. The modified pyrogram achieves complete removal of FHR in the second stage of pyrogram, while earlier researches often report residual FHR. The introduced method improves the accuracy in the identification of production potential in kerogen-rich shale reservoirs up to about 3% of the total pore volume. Further, the new approach allows a quantitative assessment for the cleaning quality without altering the sample's organic matrix. Future studies on the petrophysical properties of the hydrocarbon-bearing reservoir rocks may benefit from the thorough hydrocarbon removal achieved through the modified pyrogram methods proposed in this study.","core cleaning; kerogen richness; modified pyrolysis method; quantitative evaluation; shale","en","journal article","","","","","","","","","","","Reservoir Engineering","","",""
"uuid:a6d85734-05ae-4808-ab45-51a4dbd424f0","http://resolver.tudelft.nl/uuid:a6d85734-05ae-4808-ab45-51a4dbd424f0","Suspended AlGaN/GaN HEMT NO2 Gas Sensor Integrated with Micro-heater","Sun, J. (TU Delft Electronic Components, Technology and Materials; China Research Institute); Sokolovskij, R. (TU Delft Electronic Components, Technology and Materials; Southern University of Science and Technology; State Key Laboratory of Solid State Lighting); Iervolino, E. (TU Delft Electronic Components, Technology and Materials); Liu, Zewen (Tsinghua University); Sarro, Pasqualina M (TU Delft Electronic Components, Technology and Materials); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2019","We developed an AlGaN/GaN high electron mobility transistor (HEMT) sensor with a tungsten trioxide (WO3) nano-film modified gate for nitrogen dioxide (NO2) detection. The device has a suspended circular membrane structure and an integrated micro-heater. The thermal characteristic of the Platinum (Pt) micro-heater and the HEMT self-heating are studied and modeled. A significant detection is observed for exposure to a low concentration of 100 ppb NO2 /N2 at ∼300 °C. For a 1 ppm NO2 gas, a high sensitivity of 1.1% with a response (recovery) time of 88 second (132 second) is obtained. The effects of relative humidity and temperature on the gas sensor response properties in air are also studied. Based on the excellent sensing performance and inherent advantages of low power consumption, the investigated sensor provides a viable alternative high performance NO2 sensing applications. It is suitable for continuous environmental monitoring system or high temperature applications.","GaN; HEMT; micro-heater; NO sensor; WO","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.","","2021-08-02","","","Electronic Components, Technology and Materials","","",""
"uuid:52fa55cd-90c1-4518-abf4-94d63a333aae","http://resolver.tudelft.nl/uuid:52fa55cd-90c1-4518-abf4-94d63a333aae","Learning from Agri-Aquaculture for Multiscale Water-Sensitive Design in the Pearl River Delta","Sun, Chuanzhi (Student TU Delft); Nijhuis, S. (TU Delft Landscape Architecture); Bracken, G. (TU Delft Spatial Planning and Strategy)","","2019","The Pearl River Delta (PRD) is a river dominated floodplain in southeast China. Decreasing space for water, through dike-ring construction, channelization, and urbanization, has led to increased flood risk from river, rain, and sea. To protect from flood risk, a more adaptive urbanization strategy is required; one takes into account a multiscale approach while investigating agri-aquaculture, i.e. ecological agriculture, for example, the dike-pond system which makes use of traditional water management methods. The objective of this article is to identify landscape architecture principles for multiscale water-sensitive design based on traditional agri-aquacultural practices in the region. In the Shunde district (a flood prone lowland located between the West and North rivers of the PRD) there is a centuries’ old tradition of working with water via integrated agri-aquaculture systems. By learning from traditional agri-aquacultural practices, new design principles can be developed to mitigate flood risk while allowing for increased but sustainable urbanization, not just for the Shunde district, but also for the PRD, so that these areas can be more resilient to floods in the future.","landscape architecture; adaptive urban transformation; water-sensitive design; multiscale strategy; dike-pond system; landscape design principles","mul","journal article","","","","","","","","","","","Spatial Planning and Strategy","","",""
"uuid:8812a115-ba64-4970-b6ba-e124f2dc2a7e","http://resolver.tudelft.nl/uuid:8812a115-ba64-4970-b6ba-e124f2dc2a7e","Particle filter for aircraft mass estimation and uncertainty modeling","Sun, Junzi (TU Delft Control & Simulation); Blom, H.A.P. (TU Delft Air Transport & Operations; National Aerospace Laboratory - Netherlands); Ellerbroek, Joost (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Operations)","","2019","This article investigates the estimation of aircraft mass and thrust settings of departing aircraft using a recursive Bayesian method called particle filtering. The method is based on a nonlinear state-space system derived from aircraft point-mass performance models. Using only aircraft surveillance data, flight states such as position, velocity, wind speed, and air temperature are collected and used for the estimations. With the regularized Sample Importance Re-sampling particle filter, we are able to estimate the aircraft mass within 30 seconds once an aircraft is airborne. Using this short flight segment allows the assumption of constant mass and thrust setting. The segment at the start of the climb also represents the time when maximum thrust setting is most likely to occur. This study emphasizes an important aspect of the estimation problem, the observation noise modeling. Four observation noise models are proposed, which are all based on the native navigation accuracy parameters that have been obtained automatically from the surveillance data. Simulations and experiments are conducted to test the theoretical model. The results show that the particle filter is able to quantify uncertainties, as well as determine the noise limit for an accurate estimation. The method of this study is tested with a data-set consisting of 50 Cessna Citation II flights where true masses were recorded.","Aircraft; Bayesian estimation; Observation noise; Particle filter; Point-mass model; State estimation","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-12-01","","Control & Operations","Control & Simulation","","",""
"uuid:af94d535-1853-4a6c-8b3f-77c98a52346a","http://resolver.tudelft.nl/uuid:af94d535-1853-4a6c-8b3f-77c98a52346a","Open Aircraft Performance Modeling: Based on an Analysis of Aircraft Surveillance Data","Sun, Junzi (TU Delft Control & Simulation)","Hoekstra, J.M. (promotor); Ellerbroek, Joost (copromotor); Delft University of Technology (degree granting institution)","2019","A large number of stakeholders exist in the modern air traffic management ecosystem. Air transportation studies benefit from collaboration and the sharing of knowledge and findings between these different players. However, not all parties have equal access to information. Due to the lack of open-source tools and models, it is not always possible to undertake comparative studies and to repeat experiments. The barriers to accessing proprietary tools and models create major limitations in the field of air traffic management research. This dissertation investigates the methods necessary to construct an aircraft performance model based on open data, which can be used freely and redistributed without restrictions. The primary data source presented in this dissertation is aircraft surveillance data that can be intercepted openly with little to no restriction in most regions of the world. The eleven chapters in this dissertation follow the sequence of open data, open models, and performance estimations. This order corresponds to the three main parts of the dissertation. In the first part of the dissertation, open surveillance data is explored. Methods are developed to decode and process this data. Extraction of information is also made possible thanks to machine learning algorithms. The second part of the dissertation examines the main components of the open aircraft performance model. Models related to kinematics, thrust, drag polar, fuel flow, and weather are investigated. The third part of the dissertation looks into the possibility of using surveillance data to estimate aircraft performance parameters, for example, aircraft turn performance, aircraft mass, and thrust settings, for individual flights. With the goal of making future air traffic management studies more transparent, comparable, and reproducible, the models and tools proposed in this dissertation are fully open. The final aircraft performance model, OpenAP, proposed in this dissertation has proven to be an efficient open alternative to current closed-source models.","Aircraft Performance; Air Traffic Management; ADS-B; Drag Polar; Dynamic Model; Engine Fuel Flow; Kinematic Model; Meteo-Particle; Mode-S; Open Data; State Estimation; Thrust","en","doctoral thesis","","978-94-6384-030-9","","","","","","2019-12-09","","","Control & Simulation","","",""
"uuid:7d912f69-47d5-4f2e-9f8c-b6a6721adb55","http://resolver.tudelft.nl/uuid:7d912f69-47d5-4f2e-9f8c-b6a6721adb55","Indentation hardness, plasticity and initial creep properties of nanosilver sintered joint","Zhang, H. (TU Delft Electronic Components, Technology and Materials; Harbin University of Science and Technology); Liu, Y. (TU Delft Electronic Components, Technology and Materials; Harbin University of Science and Technology); Wang, Lingen (Boschman Technologies); Sun, Fenglian (Harbin University of Science and Technology); Fan, Xuejun (Lamar University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2019","The nanoindentation test was conducted in this paper to investigate the indentation hardness, plasticity and initial creep properties of pressure sintered nanosilver joint at various test temperatures. The effects of strain rate on the indentation hardness were first investigated. Then yield stress of nanosilver sintered joint was studied in various pressures sintered joints and the corresponding plastic stress-strain constitutive equations were gained. The maximum indentation depth of nanosilver sintered joint was obviously affected by the test temperature and sintering pressure. The indentation hardness of nanosilver sintered joint decreased with increasing test temperature from 140 to 200°C, which can be attributed to the increased amount of thermal vacancies at high temperatures. However, the indentation modulus exhibited decrease trend as the temperature increased. It is suggested that the distance between adjacent atoms was enlarged at elevated temperatures and furtherly resulted in the decrease of indentation modulus. In addition, the increased sintering pressure from 5 to 30 MPa improved the indentation hardness and modulus of sintered joint. The initial creep was observed in nanosilver sintered joint at temperatures ranged from 140 to 200°C. The increase of sintering pressure improved the resistance to creep of nanosilver sintered joint.","Indentation hardness; Initial creep; Nanosilver; Plastic deformation; Sintering pressure; OA-Fund TU Delft","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:7b5c24a1-991e-411e-a3f7-aa48a9046e38","http://resolver.tudelft.nl/uuid:7b5c24a1-991e-411e-a3f7-aa48a9046e38","Incremental Model-Based Global Dual Heuristic Programming for Flight Control","Sun, B. (TU Delft Control & Simulation); van Kampen, E. (TU Delft Control & Simulation)","","2019","This paper proposes a novel adaptive dynamic programming method, called Incremental model-based Global Dual Heuristic Programming, to generate a self-learning adaptive controller, in the absence of sufficient prior knowledge of system dynamics. An incremental technique is employed for online model identification, instead of the artificial neural networks commonly used in conventional Global Dual Heuristic Programming. The incremental model has the capability of tackling nonlinearity and uncertainty of the plant, but can also guarantee high precision of online identification without the requirement of offline training. On the basis of the identified model, two neural networks are adopted to facilitate the implementation of the self-learning controller, by approximating the cost-to-go and its derivatives and the control policy, respectively. Both methods are applied to a tracking control problem of a nonlinear aerospace system and the results show that the proposed method outperforms conventional Global Dual Heuristic Programming in online learning speed, tracking precision and robustness to variation of initial system states and network weights.","adaptive control; Adaptive dynamic programming; artificial neural network; global dual heuristic programming; incremental technique","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:25d84a4a-b4b0-4070-9503-f05f1593dccc","http://resolver.tudelft.nl/uuid:25d84a4a-b4b0-4070-9503-f05f1593dccc","Pre-Treatments Of Mswi Bottom Ash For The Application As Supplementary Cementitious Material In Blended Cement Paste","Chen, B. (TU Delft Materials and Environment); Sun, Yubo (Student TU Delft); Jacquemin, Loic (Student TU Delft); Zhang, Shizhe (TU Delft Materials and Environment); Blom, Kees (Gemeente Rotterdam); Lukovic, M. (TU Delft Concrete Structures); Ye, G. (TU Delft Materials and Environment)","Serdar, Marijana (editor); Štirmer, Nina (editor); Provis, John (editor)","2019","At present, most municipal solid waste incineration (MSWI) bottom ash, as being disposed of as waste, is directly landfilled, raising concern about the environmental issue and potential loss of resources. Given that the natural raw materials used for cement production are being depleted, the recycling of MSWI bottom ash for the application as building materials is meaningful and promising. The feasibility of using MSWI bottom ash as mineral additives in concrete has been demonstrated in the literature. In this research, as-received MSWI bottom ash has high mineral content and shows stable leaching behaviour. But, when used as cement substitute, the residual metallic Al in bottom ash always causes matrix swelling and strength loss by reacting with Ca(OH)2 and releasing H2 gas. In this research, dry and wet pretreatment methods were performed to remove the metallic Al in as-received bottom ash (0- 2mm). The results show that both of these two methods are effective. When comparing these two methods, wet method is time-consuming but can remove the metallic Al completely; dry method is fast but always has limitation that it can only reduce the metallic Al content by 80%. Regarding compressive strength, the decrease introduced by 10% dry-treated bottom replacement in cement paste is less than that of wet-treated bottom ash. The lower strength development observed in wet-treated bottom ash blended cement may be due to the removal of soluble reactive phases during the treatment.","MSWI bottom ash; cement substitute; metallic Al; pre-treatment; compressive strength","en","conference paper","RILEM publications","","","","","","","","","","Materials and Environment","","",""
"uuid:ee03c81e-33cc-4939-a66a-83d51a3911e0","http://resolver.tudelft.nl/uuid:ee03c81e-33cc-4939-a66a-83d51a3911e0","Design exploration of architectural geometries and structural performance for sports arenas based on SOM-clustering and structural performance simulation","Pan, W. (TU Delft Design Informatics; South China University of Technology); Sun, Yimin (South China University of Technology); Turrin, M. (TU Delft Design Informatics); Louter, P.C. (TU Delft OLD Structural Design); Sariyildiz, I.S. (TU Delft Design Informatics)","Cruz, Paulo (editor)","2019","Indoor sports arenas are a kind of important public buildings, which require iconic architectural forms and well performing structures for the long-span roofs. Hence, during the early stage of an arena design, it is crucial for designers to define a proper building form based on integrated design exploration of both geometric typology and structural performance. To support such design exploration, this paper proposes a method based on SOM (self-organizing map)-clustering and structural performance simulation as well as SAG (Sports Arena Generator: a specific parametric model for arenas proposed by the authors). This method can support designers to explore designs according to both geometries and performance and also illustrate the relationships between geometric typology and specific performance values, which is crucial for both architectural design
and the research about building performance. A hypothetic arena is used as an example to demonstrate and validate the method.","","en","conference paper","Taylor and Francis","","","","","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.","","2020-01-08","","","Design Informatics","","",""
"uuid:3cc1ddd6-5f89-433f-bb4f-ddf546316639","http://resolver.tudelft.nl/uuid:3cc1ddd6-5f89-433f-bb4f-ddf546316639","Dynamic analysis of layered systems under a moving harmonic rectangular load based on the spectral element method","Sun, Z. (TU Delft Pavement Engineering); Kasbergen, C. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology); Anupam, K. (TU Delft Pavement Engineering); van Dalen, K.N. (TU Delft Dynamics of Structures); Erkens, S. (TU Delft Pavement Engineering)","","2019","In order to design high-performance roadways, a robust tool which can compute the structural response caused by moving vehicles is necessary. Therefore, this paper proposes a spectral element method-based model to accurately and effectively predict the 3D dynamic response of layered systems under a moving load. A layer spectral element and a semi-infinite spectral element are developed to respectively model a layer and a half-space, and the combinations of these two elements can simulate layered systems. The detailed mathematical derivation and numerical validation of the proposed model are included. Additionally, this model is used to investigate the dynamic characteristics of a pavement structure under a moving harmonic rectangular load. The results show that the proposed model can accurately predict the dynamic response of layered systems caused by a moving load. It is also found that the vertical displacement amplitude curves of surface points caused by a moving harmonic load are asymmetric along the moving direction, and this property is more dominant at higher velocities. In addition, the amplitudes of these vertical displacements are smaller if the loading frequency is higher or the loss factor is bigger. Finally, the loading area and Poisson's ratio only have effect on the displacement amplitudes of points in the close vicinity of the loading area. The proposed model is beneficial to the development of engineering methods for pavement design and is a promising parameter back-calculation engine for pavement quality evaluation.","Dynamic response; Layered systems; Moving load; Spectral element method; Doppler effect","en","journal article","","","","","","Accepted Author Manuscript","","2021-08-13","","","Pavement Engineering","","",""
"uuid:90fbc5c8-00c1-43c4-9045-19ee1ce607b0","http://resolver.tudelft.nl/uuid:90fbc5c8-00c1-43c4-9045-19ee1ce607b0","Why Factory: The spatial significance of Architectural Education Buildings","Zhu, Fengji (Soochow University); Sun, L. (TU Delft History, Form & Aesthetics; Soochow University); Zhu, K. (TU Delft History, Form & Aesthetics); Jing, Liping (Soochow University)","","2019","The educational space of Architecture faculty is used to cultivate architects. At the same time, it becomes the carrier of architectural ideas and teaching methods. The type of architecture and its spatial organization reflect the architectural education philosophy and attitude. Back in history, as early as the Renaissance, there had emerged study places for architects. After the industrial revolution and the modernist process, the types of architectural education sites are more diverse, and their main features are the spatial form of hybrid and box-in-box. This article preliminarily analyzes the evolutionary outline of architectural education buildings and interprets the spatial ideas in each period. The study focuses on the famous Dutch architectural school--BKCity of the Delft University of Technology, analyzing the teaching space logic of its distinctive Why Factory and exploring how the related space could stimulate the vitality of architectural education. By the analogy of some architectural schools, it also tries to compare the differences and characteristics of Chinese and Western architectural academies, finding out the spatial significance in architecture discipline, education method as well as sustainable application.","School of Architecture; BKCity; Educational Space; Cognitive Experience; Sustainable Application","en","conference paper","KnE Social Sciences","","","","","","","","","","History, Form & Aesthetics","","",""
"uuid:7f82afb6-d4dd-441c-83a6-8babfaffefd5","http://resolver.tudelft.nl/uuid:7f82afb6-d4dd-441c-83a6-8babfaffefd5","乡村体验视角下特色田园乡村景观空间分析与优化研究——以苏州市树山村为例","Zha, Jingrong; Xie, Guoqi; Sun, L. (TU Delft History, Form & Aesthetics)","","2019","Under the background of coordinated development between urban and rural areas, rural revival is a hot topic. The research focuses on the landscape spatial form under the Characteristic and Idyllic Village. From the perspective of rural experience, it uses settlement space and landscape space analysis method to construct the renewal strategy of experiential characteristic rural style, and then explores the blending and overlapping mode of rural form, function, personality and landscape space. Taking the HuChaoli in shushan village of suzhou city as the sample, the landscape spatial organization system was analyzed. The landscape pattern, spatial sequence and experience depth under the guidance of experience are discussed from the three dimensions of ""participation, relevance and complexity"". In view of the rural landscape space, the renewal method is proposed to promote the interaction and integration of ""rural experience"" and ""landscape form"", so as to obtain the systematic and adaptive optimization strategy in line with the internal mechanism of Characteristic and Idyllic Village.","Rural Experience; Characteristic and Idyllic Village; Landscape Space; Analysis and Optimizing Strategy","zh","journal article","","","","","","","","","","","History, Form & Aesthetics","","",""
"uuid:927e6a25-0d32-4400-86dd-724bb1828a95","http://resolver.tudelft.nl/uuid:927e6a25-0d32-4400-86dd-724bb1828a95","“轻”之观念:新芽体系的人本内涵与衍生启示","Sun, L. (TU Delft History, Form & Aesthetics); Zhao, Pingping; Xu, Qingqing","","2019","This paper reviews the development of New-Bud System, analyzes the humanistic connotation of“light-weight”comparing with Japanese architect Shigeru’s similar practices, and interprets New-Bud’s construction concept based on humanism and its “autonomic, evolving, derivative”systematic vitality. The concept and pursuit of“light-weight for construction”will also indicate more pluralistic possibilities and follow-ups for the marginal expansion and transformation of architecture.","New-Bud System; construction concept; Humanism; autonomous derivatization; Zhu Jingxiang; Shigeru Ban","zh","journal article","","","","","","","","","","","History, Form & Aesthetics","","",""
"uuid:eb58cc94-9f45-4ff6-b786-c47274b62f6b","http://resolver.tudelft.nl/uuid:eb58cc94-9f45-4ff6-b786-c47274b62f6b","The Practice and Enlightenment of Architectural Renovation and Urban Renewal in the Netherlands","Liping, Jing (Soochow University); Sun, L. (TU Delft History, Form & Aesthetics; Soochow University); Zhu, K. (TU Delft History, Form & Aesthetics); Zhu, Fengji (Soochow University)","","2019","Since the development of architectural disciplines, Dutch architectural style and architects have played important role in the world. In the wave of local urban renewal in the Netherlands, Dutch architects represented by Rem Koolhass, Francine Houben, Winy Maas and Kees Kaan and etc. have shown rich practices and experiences, therefore, the architectural renovation and urban renewal have show prosperous scenarios. This paper focuses on the four types of architectural and urban transformation practices in the Netherlands, named as Regional renewal, architectural heritage refurbishment, adaptive reuse and industrial building renovation [1], and analyzes typical cases such as Westerpark West, Speelhuis theater, Timmerhuis and Villa Industria project. Exploring the role and spatial stance of Dutch architects, the research tries to sum up the Dutch modes and experiences, and provides a new perspective and method for similar transformation practices in urban renewal of contemporary China.","","en","poster","","","","","","","","","","","History, Form & Aesthetics","","",""
"uuid:5fc8c392-a891-4840-8b3e-9af4a1525259","http://resolver.tudelft.nl/uuid:5fc8c392-a891-4840-8b3e-9af4a1525259","Challenges and the Road Ahead for Intermodal Freight Terminals","Huynh, Nathan (University of South Carolina); Smith, Daniel (Tioga Group); van Duin, Ron (TU Delft Transport and Logistics; Rotterdam University of Applied Sciences); Dulebenets, Maxim (Florida State University); Sun, Yansuhuo (Florida State University); Schonfeld, Paul (University of Maryland); Hutson, Nathan (University of Southern California); Sauri, Sergi (CENIT-Polytechnic University of Catalonia); Dau-Ngo, Theresa (Port of Long Beach); Harder, Frank (Tioga Group); Khankarli, Ghassan (City of Dallas)","","2019","","intermodal freight transport; terminals","en","report","Transportation Research Board (TRB)","","","","","","","","","","Transport and Logistics","","",""
"uuid:44e54716-6f76-45d9-97ce-01478f4d4cf5","http://resolver.tudelft.nl/uuid:44e54716-6f76-45d9-97ce-01478f4d4cf5","Communal Space and Degree of Sharing: The Legacy and Inspiration of Juer Hutong Neighborhood Project","Sun, Wenwen (TU Delft Theory, Territories & Transitions)","","2019","","Chinese dwelling design; communal space; courtyard housing; new quadrangle; public-private gradient; urban regeneration design","en","abstract","","","","","","","","","","","Theory, Territories & Transitions","","",""
"uuid:fdfcf76b-421a-44a2-b01f-f229dc3ed57e","http://resolver.tudelft.nl/uuid:fdfcf76b-421a-44a2-b01f-f229dc3ed57e","Negotiated Public: An Investigation on the Streetscape of Beijing’s Old City","Sun, Wenwen (TU Delft Theory, Territories & Transitions)","","2019","In Beijing’s old city, the emergence of conflictual practices in the street life have challenged the conventional concepts of ‘public’ and ‘private’, as well as the design principles based on this normative expression. This paper proposes a novel way of reading and understanding the street spaces by exploring a traditional type of street in Beijing— namely the hutong — through its controversial and conflicting spatial practices and ambiguous social expressions. Substantiated by the practice of lived experience, it argues that instead of a given urban condition or an idealised category of urban design, public space is best understood as a dynamic realm negotiated and renegotiated by simultaneous solid and soft interventions from multiple social groups. This argument hopes to open discussions towards a more localised and inclusive understanding of public space in the Chinese city.","appropriation; negotiation; public space; the streetscape","en","abstract","","","","","","","","","","","Theory, Territories & Transitions","","",""
"uuid:d75c9dad-a536-453d-81a6-4888a325f851","http://resolver.tudelft.nl/uuid:d75c9dad-a536-453d-81a6-4888a325f851","Characterization of an Acetone Detector based on a Suspended WO3-Gate AlGaN/GaN HEMT Integrated with Micro-heater","Sun, J. (TU Delft Electronic Components, Technology and Materials; Chinese Research Institute); Sokolovskij, R. (TU Delft Electronic Components, Technology and Materials; Southern University of Science and Technology); Iervolino, E. (USound Shenzhen Office); Santagata, F. (Shenzhen 3NOD Acousticlink Company,); Liu, Zewen (Tsinghua University); Sarro, Pasqualina M (TU Delft Electronic Components, Technology and Materials); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2019","A suspended AlGaN/GaN high electron mobility transistor (HEMT) sensor with a tungsten trioxide (WO 3 ) nanofilm modified gate was microfabricated and characterized for ppm-level acetone gas detection. The sensor featured a suspended circular membrane structure and an integrated microheater to select the optimum working temperature. High working temperature (300°C) increased the sensitivity to up to 25.7% and drain current change I DS to 0.31 mA for 1000-ppm acetone in dry air. The transient characteristics of the sensor exhibited stable operation and good repeatability at different temperatures. For 1000-ppm acetone concentration, the measured response and recovery times reduced from 148 and 656 to 48 and 320 s as the temperature increased from 210 °C to 300 °C. The sensitivity to 1000-ppm acetone gas was significantly greater than the sensitivity to ethanol, ammonia, and CO gases, showing low cross-sensitivity. These results demonstrate a promising step toward the realization of an acetone sensor based on the suspended AlGaN/GaN HEMTs.","Acetone sensor; AlGaN/GaN; WO₃; gas sensor; high electron mobility transistor (HEMT)","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.","","2021-08-02","","","Electronic Components, Technology and Materials","","",""
"uuid:61c21b75-bda0-460a-b185-dac7459020f4","http://resolver.tudelft.nl/uuid:61c21b75-bda0-460a-b185-dac7459020f4","Quadrotor Fault Tolerant Incremental Sliding Mode Control driven by Sliding Mode Disturbance Observers","Wang, Xuerui (TU Delft Control & Simulation); Sun, S. (TU Delft Control & Simulation); van Kampen, E. (TU Delft Control & Simulation); Chu, Q. P. (TU Delft Control & Simulation)","","2019","This paper proposes an Incremental Sliding Mode Control driven by Sliding Mode Disturbance Observers (INDI-SMC/SMDO), with application to a quadrotor fault tolerant control problem. By designing the SMC/SMDO based on the control structure of the sensor-based Incremental Nonlinear Dynamic Inversion (INDI), instead of the model-based Nonlinear Dynamic Inversion (NDI) in the literature, the model dependency of the controller and the uncertainties in the closed-loop system are simultaneously reduced. This allows INDI-SMC/SMDO to passively resist a wider variety of faults and external disturbances using continuous control inputs with lower control and observer gains. When applied to a quadrotor, both numerical simulations and real-world flight tests demonstrate that INDI based SMC/SMDO has better performance and robustness over NDI based SMC/SMDO, in the presence of model uncertainties, wind disturbances, and sudden actuator faults. Moreover, the implementation process is simplified because of the reduced model dependency and smaller uncertainty variations of INDI-SMC/SMDO. Therefore, the proposed control method can be easily implemented to improve the performance and survivability of quadrotors in real life.","Fault-Tolerant Control; Incremental Nonlinear Dynamic Inversion; Quadrotor flight tests; Sliding Mode Control; Sliding Mode Disturbance Observer","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.","","2022-01-05","","","Control & Simulation","","",""
"uuid:272107b8-3cbc-42ff-956a-1aa89d6b8643","http://resolver.tudelft.nl/uuid:272107b8-3cbc-42ff-956a-1aa89d6b8643","Driving risk classification methodology for intelligent drive in real traffic event","Sun, C. (Wuhan University); Li, Bijun (Wuhan University); Li, Yicheng (Jiangsu University); Lu, Z. (TU Delft Intelligent Vehicles)","","2019","To solve the problem that existing driving data cannot correlate to the large number of vehicles in terms of driving risks, is the functionality of intelligent driving algorithm should be improved. This paper deeply explores driving data to build a link between massive driving data and a large number of sample vehicles for driving risk analysis. It sorted out certain driving behavior parameters in the driving data, and extracted some parameters closely related to the driving risk; it further utilized the principal component analysis and factor analysis in spatio-temporal data to integrate certain extracted parameters into factors that are clearly related to the specific driving risks; then, it selected factor scores of driving behaviors as indexes for hierarchical clustering, and obtained multi-level clustering results of the driving risks of corresponding vehicles; in the end, it interpreted the clustering results of the vehicle driving risks. According to the results, it is found that cluster for different risks proposed in this paper for driving behaviors is effective in the hierarchical cluster for typical driving behaviors and it also offers a solution for risk analyses between driving data and large sample vehicles. The results provide the basis for training on safe driving for the key vehicles, and the improvement of advanced driver assistance system, which shows a wide application prospect in the field of intelligent drive.","classification methodology; driving data; intelligent drive; Vehicle driving risk","en","journal article","","","","","","","","","","","Intelligent Vehicles","","",""
"uuid:536530fd-6516-4b19-afd1-c02ee6202a8a","http://resolver.tudelft.nl/uuid:536530fd-6516-4b19-afd1-c02ee6202a8a","Negotiated Public: Investigating the Streetscape of Beijing’s Old City","Sun, Wenwen (TU Delft Theory, Territories & Transitions)","","2019","","appropriation; negotiation; public space; the streetscape","en","conference paper","AESOP","","","","","","","","","","Theory, Territories & Transitions","","",""
"uuid:2f4f8ee4-d296-423d-b866-f9266d3af949","http://resolver.tudelft.nl/uuid:2f4f8ee4-d296-423d-b866-f9266d3af949","The role of aerosol layer height in quantifying aerosol absorption from ultraviolet satellite observations","Sun, J. (TU Delft Atmospheric Remote Sensing); Veefkind, j. Pepijn (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI)); Nanda, S. (TU Delft Atmospheric Remote Sensing); Van Velthoven, Peter (Royal Netherlands Meteorological Institute (KNMI)); Levelt, Pieternel Felicitas (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI))","","2019","The purpose of this study is to demonstrate the role of aerosol layer height (ALH) in quantifying the single scattering albedo (SSA) from ultraviolet satellite observations for biomass burning aerosols. In the first experiment, we retrieve SSA by minimizing the near-ultraviolet (near-UV) absorbing aerosol index (UVAI) difference between observed values and those simulated by a radiative transfer model. With the recently released S-5P TROPOMI ALH product constraining forward simulations, a significant gap in the retrieved SSA (0.25) is found between radiative transfer simulations with spectral flat aerosols and those with strong spectrally dependent aerosols, implying that inappropriate assumptions regarding aerosol absorption spectral dependence may cause severe misinterpretations of the aerosol absorption. In the second part of this paper, we propose an alternative method to retrieve SSA based on a long-term record of co-located satellite and ground-based measurements using the support vector regression (SVR) approach. This empirical method is free from the uncertainties due to the imperfection of a priori assumptions on aerosol microphysics seen in the first experiment. We present the potential capabilities of SVR using several fire events that have occurred in recent years. For all cases, the difference between SVR-retrieved SSA and AERONET are generally within ±0:05, and over half of the samples are within ±0:03. The results are encouraging, although in the current phase the model tends to overestimate the SSA for relatively absorbing cases and fails to predict SSA for some extreme situations. The spatial contrast in SSA retrieved by radiative transfer simulations is significantly higher than that retrieved by SVR, and the latter better agrees with SSA from MERRA-2 reanalysis. In the future, more sophisticated feature selection procedures and kernel functions should be taken into consideration to improve the SVR model accuracy. Moreover, the high-resolution TROPOMI UVAI and co-located ALH products will guide us to more reliable training data sets and more powerful algorithms to quantify aerosol absorption from UVAI records.","","en","journal article","","","","","","","","","","","Atmospheric Remote Sensing","","",""
"uuid:0d5fb22c-ae3e-4bab-aed0-23653ac1c26d","http://resolver.tudelft.nl/uuid:0d5fb22c-ae3e-4bab-aed0-23653ac1c26d","pyModeS: Decoding Mode-S Surveillance Data for Open Air Transportation Research","Sun, Junzi (TU Delft Control & Simulation); Vû, Huy (Student TU Delft); Ellerbroek, Joost (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Operations)","","2019","The availability of low-cost automatic dependent surveillance-broadcast (ADS-B) receivers has given researchers the ability to make use of large amounts of aircraft state data. This data is being used to support air transportation research in performance study, trajectory prediction, procedure analysis, and airspace design. However, aircraft states contained in ADS-B messages are limited. More performance parameters are downlinked as Mode-S Comm-B replies, upon the automatic and periodic interrogation of air traffic control secondary surveillance radar. These replies reveal aircraft airspeed, turn rate, target altitude, and so on. They can be intercepted using the same 1090-MHz receiver that receives the ADS-B messages. However, a third-party observer does not know the interrogations, which originated the Comm-B replies. Thus, it is difficult to decode these messages without knowing the type and source aircraft. Furthermore, the parity check also cannot be performed without knowing the interrogations. In this paper, we propose a new heuristic-probabilistic method to decode the Comm-B replies and to check the correctness of the messages. Based on a reference dataset provided by air traffic control of the Netherlands, the method yields a success rate of 97.68% with an error below 0.01%. The performance of the proposed method is further examined with data from eight different regions of the world. The implementation of the inference and decoding process, pyModeS, is shared as an open-source library.","aircraft surveillance; air traffic control; Mode-S; Comm-B; Enhanced Mode-S; ADS-B","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","","Control & Operations","Control & Simulation","","",""
"uuid:fc16244c-6a91-4ff4-8a10-91ecf89d83a4","http://resolver.tudelft.nl/uuid:fc16244c-6a91-4ff4-8a10-91ecf89d83a4","Reconstructing Aircraft Turn Manoeuvres for Trajectory Analyses Using ADS-B Data","Sun, Junzi (TU Delft Control & Simulation); Ellerbroek, Joost (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Operations)","","2019","The Automatic Dependent Surveillance-Broadcast (ADS-B) data has become one of the most popular sources of data for trajectory-based ATM studies. It is can be received in most of the world without restrictions. Extended coverage can be achieved with a network of low-cost receivers and satellites. However, the fact that ADS-B is designed to contain only a low number of aircraft states such as position and velocity poses a challenge for some trajectory-based studies, for example, using ADS-B data to study aircraft turns. To this extent, air traffic controllers commonly rely on Mode-S track and turn reports to gather additional information like bank angle and turn rates during turns. Unlike ADS-B, this data has a low update rate and is not always openly available for all researchers. In this paper, we propose methods that allow researchers to extract and analyze aircraft turn parameters from ADS-B data during offline flight analysis. The paper first discusses the dynamics of aircraft turns. Then, based on ADS-B trajectory data, several steps are designed to derive turn radius, bank angle, and turn rate of an aircraft. The estimation results are validated with aircraft track and turn reports from Mode S Enhanced Surveillance. The median errors for bank angle and turn rate are found to be less than 2 degrees and 0.1 degrees/s respectively, which reflects the accuracy of the estimation approach.","aircraft performance; turn performance; bank angle; load factor; ADS-B; data analysis","en","conference paper","","","","","","","","","","Control & Operations","Control & Simulation","","",""
"uuid:69b335f8-9dcc-4c2e-ba35-17c4a667dd16","http://resolver.tudelft.nl/uuid:69b335f8-9dcc-4c2e-ba35-17c4a667dd16","Topological Approach to Measure Network Recoverability","He, Z. (TU Delft Network Architectures and Services); Sun, P. (TU Delft Network Architectures and Services); Van Mieghem, P.F.A. (TU Delft Network Architectures and Services)","Ellinas, Georgios (editor); Rak, Jacek (editor); Goscien, Roza (editor)","2019","Network recoverability refers to the ability of a network to return to a desired performance level after suffering malicious attacks or random failures. This paper proposes a general topological approach and recoverability indicators to measure the network recoverability in two scenarios: 1) recovery of damaged connections and 2) any disconnected pair of nodes can be connected to each other. Our approach presents the effect of the random attack and recovery processes on the network performance by the robustness envelopes of realizations and the histograms of two recoverability indicators. By applying the effective graph resistance and the network efficiency as robustness metrics, we employ the proposed approach to assess 10 realworld communication networks. Numerical results verify that the network recoverability is coupled to the network topology, the robustness metric and the recovery strategy. We also show that a greedy recovery strategy could provide a near-optimal recovery performance for the investigated robustness metrics.","multiple failure; Recoverability; Robusteness","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","","","","","","Network Architectures and Services","","",""
"uuid:5b05ca99-f58a-426e-bd66-ca62231f275a","http://resolver.tudelft.nl/uuid:5b05ca99-f58a-426e-bd66-ca62231f275a","Quantifying the Robustness of Network Controllability","Sun, P. (TU Delft Network Architectures and Services); Van Mieghem, P.F.A. (TU Delft Network Architectures and Services); Kooij, Robert (TU Delft Quantum & Computer Engineering; Singapore University of Technology and Design); He, Z. (TU Delft Network Architectures and Services); Van Mieghem, Piet (TU Delft Network Architectures and Services)","","2019","In this paper, we propose closed-form analytic approximations for the minimum number of driver nodes needed to fully control networks, where links are removed according to both random and targeted attacks. Our approximations rely on the concept of critical links. A link is called critical if its removal increases the required number of driver nodes. We validate our approximation on both real-world and synthetic networks. For random attacks, the approximation is always very good, as long as the fraction of removed links is smaller than the fraction of critical links. For some cases, the approximation is still accurate for larger fractions of removed links. The approximation for an attack, where first the critical links are removed, is also accurate, as long as the fraction of removed links is sufficiently small. Finally, we show that the critical link attack is the most effective among 4 considered attacks, as long as the fraction of removed links is smaller than the fraction of critical links.","Complex networks; Controllability; Robustness","en","conference paper","","","","","","","","","","Quantum & Computer Engineering","Network Architectures and Services","","",""
"uuid:84afd774-3c4f-49a5-a52e-6eb0532f322e","http://resolver.tudelft.nl/uuid:84afd774-3c4f-49a5-a52e-6eb0532f322e","WRAP: An open-source kinematic aircraft performance model","Sun, Junzi (TU Delft Control & Simulation); Ellerbroek, Joost (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2019","Open access to flight data from Automatic Dependent Surveillance-Broadcast (ADS-B) has provided researchers with more insights for air traffic management than aircraft tracking alone. With large quantities of trajectory data collected from a wide range of different aircraft types, it is possible to extract accurate aircraft performance parameters. In this paper, a set of more than thirty parameters from seven distinct flight phases are extracted for common commercial aircraft types. It uses various data mining methods, as well as a maximum likelihood estimation approach to generate parametric models for these performance parameters. All parametric models combined can be used to describe a complete flight that includes takeoff, initial climb, climb, cruise, descent, final approach, and landing. Both analytical results and summaries are shown. When available, optimal parameters from these models are also compared with the Base of Aircraft Data and the Eurocontrol aircraft performance database. This research presents a comprehensive set of methods for extracting different aircraft performance parameters. It also provides the first set of open parametric performance data for common aircraft types. All model data are published as open data under a flexible open-source license.","ADS-B; Aircraft performance; Data analytics; Data mining; Kinematic model","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-06-01","","","Control & Simulation","","",""
"uuid:05c9fc08-c81f-4356-857e-48a27e7ec7f6","http://resolver.tudelft.nl/uuid:05c9fc08-c81f-4356-857e-48a27e7ec7f6","Effects of sintering pressure on the densification and mechanical properties of nanosilver double side sintered power module","Zhang, H. (TU Delft Electronic Components, Technology and Materials; Harbin University of Science and Technology); Liu, Y. (Harbin University of Science and Technology); Wang, Lingen (Boschman Technologies); Sun, Fenglian (Harbin University of Science and Technology); Fan, Jiajie (Hohai University); Placette, Mark D. (Iowa State University); Fan, Xuejun (Lamar University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2019","Modern power electronics has the increased demands in current density and high-temperature reliability. However, these performance factors are limited due to the die attach materials used to affix power dies microchips to electric circuitry. Although several die attach materials and methods exist, nanosilver sintering technology has received much attention in attaching power dies due to its superior high-temperature reliability. This paper investigated the sintering properties of nanosilver film in double-side sintered power packages. X-ray diffraction results revealed that the size of nanosilver particles increased after pressure-free sintering. Compared with the pressure-free sintered nanosilver particles, the 5-MPa sintered particles showed a higher density. When increasing sintering pressure from 5 to 30 MPa, the shear strength of the sintered package increased from 8.71 to 86.26 MPa. When sintering at pressures below 20 MPa, the fracture areas are mainly located between the sintered Ag layer and the surface metallization layer on the fast recovery diode (FRD) die. The fracture occurs through the FRD die and the metallization layer on the bottom molybdenum substrate when sintering at 30 MPa.","Fracture; nanosilver sintering; power electronics; shear strength","en","journal article","","","","","","Accepted author manuscript","","","","","Electronic Components, Technology and Materials","","",""
"uuid:a726da1b-f68d-46db-9e3a-b365b9f34614","http://resolver.tudelft.nl/uuid:a726da1b-f68d-46db-9e3a-b365b9f34614","Tailoring Li6PS5BR ionic conductivity and understanding of its role in cathode mixtures for high performance all-solid-state Li-S batteries","Yu, C. (TU Delft RST/Storage of Electrochemical Energy); Hageman, J.G. (Student TU Delft); Ganapathy, S. (TU Delft RST/Storage of Electrochemical Energy); van Eijck, L. (TU Delft RST/Neutron and Positron Methods in Materials); Zhang, Long (Yanshan University); Adair, Keegan R. (University of Western Ontario); Sun, Xueliang (University of Western Ontario); Wagemaker, M. (TU Delft RST/Storage of Electrochemical Energy)","","2019","The ultrafast ionic conductivity of Li 6 PS 5 Br, which is higher than 1 mS cm -1 at room temperature, makes it an attractive candidate electrolyte for the all-solid-state Li-S battery. A simple synthesis route with an easy scale up process is critical for practical applications. In this work, the highest room temperature ionic conductivity (2.58 × 10 -3 S cm -1 ) of Li 6 PS 5 Br is obtained by an optimal annealing temperature in a simple solid-state reaction method. Neutron diffraction and XRD show that the origin of the highest ionic conductivity is due to the higher purity, smaller mean lithium ion jumps and the optimal Br ordering over 4a and 4c sites. All-solid-state Li-S batteries using a S-C composite cathode in combination with the optimized Li 6 PS 5 Br electrolyte and Li-In anode show high (dis)charge capacities. Different cycling modes (charge-discharge and discharge-charge) reveal that the capacity of the S-C-Li 6 PS 5 Br/Li 6 PS 5 Br/Li-In battery arises from both the active S-C composite and the Li 6 PS 5 Br in the cathode mixture. The contribution of the latter is verified from all-solid-state batteries using Li 6 PS 5 Br and its analogues as active materials. Ex situ XRD and electrochemical performance results show that the contribution of capacity from Li 6 PS 5 Br in the cathode mixture may be associated with the decomposition product Li 2 S, while the Li 6 PS 5 Br in the bulk solid electrolyte layer is stable during cycling.","","en","journal article","","","","","","Accepted Author Manuscript","","2020-04-05","","","RST/Storage of Electrochemical Energy","","",""
"uuid:a1f250de-903e-4b8b-87bb-c80bfecd6063","http://resolver.tudelft.nl/uuid:a1f250de-903e-4b8b-87bb-c80bfecd6063","3-D Linear Reconstruction of the Experimental Fresnel Data by the GMMV Inversion Method","Sun, S. (National University of Defense Technology); Kooij, B.J. (TU Delft Microwave Sensing, Signals & Systems); Yarovoy, Alexander (TU Delft Microwave Sensing, Signals & Systems)","","2019","In this paper, the generalized multiple measurement vectors (GMMV) linear inversion method is applied to the reconstruction of the 3-D Fresnel data, provided by the Institue Fresnel (Marseille, France). The results show that the GMMV-based method can obtain good resolution along the x- and y- axes, while poor resolution along the z-axis, because there were only receiving antennas distributed on the x-o-y plane, indicating that the diversity of the measurement angle is critical for the GMMV method.","Image reconstruction; Imaging; Inverse problems; Receivers; Scattering; Shape; Integrated circuits","en","conference paper","IEEE","","","","","green","","","","","Microwave Sensing, Signals & Systems","","",""
"uuid:ea44a0be-9eeb-4912-903f-f99f3f47cf42","http://resolver.tudelft.nl/uuid:ea44a0be-9eeb-4912-903f-f99f3f47cf42","Long-Term Cumulative Effects of Intra-Annual Variability of Unsteady River Discharge on the Progradation of Delta Lobes: A Modeling Perspective","Gao, Weilun (Beijing Normal University); Shao, Dongdong (Beijing Normal University); Wang, Zhengbing (TU Delft Coastal Engineering; Beijing Normal University); Nardin, William (University of Maryland Center for Environmental Science); Rajput, Prateek (Indian Institute of Technology Kanpur); Yang, Wei (Beijing Normal University); Sun, Tao (Beijing Normal University); Cui, Baoshan (Beijing Normal University)","","2019","Rivers, regardless of their scales and geographic locations, are characterized with natural and human-induced variability in their discharges. While previous studies have established the effects of both interannual and intra-annual variabilities of unsteady river discharge on delta morphological evolution, the long-term cumulative effects of intra-annual unsteadiness on the progradation of delta lobes has remained hitherto elusive. To address this issue, numerical experiments using simplified unsteady discharges were performed in Delft3D and compared with those assuming constant bank-full discharges. A modified box model was further used to explore the effects of varying intra-annual unsteadiness on the progradation of delta lobes at reduced computational cost. While the overall trends of the progradation and the ultimate area created were found to be similar between the unsteady discharge scenarios and their corresponding constant bank-full discharge scenarios, the nuances of intermittent zig-zag variation in natural delta lobe area were well reproduced by model simulations assuming unsteady river discharges. In addition, long-term predictions suggested the potential existence of a tipping point in the area growth trajectory beyond which the delta lobe area declines during periods of low discharge. When confounding factors such as waves and variable sediment capture ratio were further taken into consideration, simulation results for unsteady river discharge scenarios exhibit significant deviations from constant bank-full discharge scenarios. The implications of the modeling results for delta protection and restoration measures, such as the water-sediment regulation scheme in the Yellow River and artificial channel diversions in the Mississippi River Delta, are also discussed.","delta progradation; delta restoration; numerical modeling; unsteady river discharge","en","journal article","","","","","","Accepted Author Manuscript","","","","","Coastal Engineering","","",""
"uuid:57a83268-ffd4-4f3b-b00a-1317a9e39ac0","http://resolver.tudelft.nl/uuid:57a83268-ffd4-4f3b-b00a-1317a9e39ac0","High-Speed Distance Relaying of the Entire Length of Transmission Lines without Signaling","Azizi, Sadegh (University of Leeds); Sun, Mingyu (The University of Manchester); Liu, Gaoyuan (The University of Manchester); Popov, M. (TU Delft Intelligent Electrical Power Grids); Terzija, Vladimir (The University of Manchester)","","2019","Short-circuit faults close to either end of a transmission line, are normally cleared instantaneously by the distance relay at that end and after hundreds of milliseconds, i.e., in Zone 2 operating time, by the relay at the opposite end of the line. This sequential tripping can be accelerated on condition that a reliable communication link is available for signaling between the two line ends. This paper proposes a novel non-communication method providing high-speed distance relaying over the entire length of the protected transmission line. The inputs to the method are the protected line parameters and local voltage and current signals measured by the relay, similar to those to conventional distance relays. The proposed method accomplishes Accelerated Sequential Tripping (AST) within a couple of cycles after the opening of the remote-end circuit breaker (ORCB) of the line. To achieve this, an accurate closed-form solution is derived for the fault distance in terms of post-ORCB voltage and current phasors. For the detection of the ORCB instant, a set of proper indices are proposed. This is to verify the fault distance calculated by the relay, before issuing a trip command. The proposed method is successfully validated by conducting more than 20000 hardware-in-the-loop (HIL) tests, and also using real-life data.","Accelerated sequential tripping (AST); Distance relays; Opening of the remote-end circuit breaker (ORCB); Real-time digital simulator (RTDS)","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.","","2021-05-03","","","Intelligent Electrical Power Grids","","",""
"uuid:24eeddeb-dff3-4c8e-9492-4715b8473b9a","http://resolver.tudelft.nl/uuid:24eeddeb-dff3-4c8e-9492-4715b8473b9a","Noncomunication accelerated sequential tripping for remote-end faults on transmission lines","Azizi, Sadegh (The University of Manchester); Sun, Mingyu (The University of Manchester); Terzija, Vladimir (The University of Manchester); Popov, M. (TU Delft Intelligent Electrical Power Grids)","","2019","Short-circuit faults occurring close to either end of a transmission line are normally cleared with some time delay by the distance relay at the opposite end of that line. The pilot relaying schemes require communication media in order to reduce this time delay. This paper presents a noncommunication method that provides high-speed distance relaying over the entire length of transmission lines. Similar to conventional distance relays, the proposed method requires voltage and current signals at the relay location as well as the impedance parameters of the protected line as input. Accelerated sequential tripping (AST) for faults on the end-sections of the line is achieved by using the signals measured from the fault inception to several cycles after the opening of the remote-end circuit breaker (ORCB). A formula is put forward for determining the exact fault distance by using post-ORCB signals. Two indices are also proposed for detecting three-and single-pole ORCB in order to fulfill the prerequisite for accurate fault location and generating a trip command, if needed. The proposed method is validated by conducting more than 10000 simulations on the 39-bus test system using DIgSILENT PowerFactory.","Accelerated sequential tripping; Discrete fourier transform (DFT); Distance relay; Opening of the remote-end circuit breaker (ORCB)","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.","","2021-05-03","","","Intelligent Electrical Power Grids","","",""
"uuid:d08cc8a9-4c3c-4b55-9abc-4442647ea044","http://resolver.tudelft.nl/uuid:d08cc8a9-4c3c-4b55-9abc-4442647ea044","Integrating pyModeS and OpenSky Historical Database","Sun, Junzi (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Operations)","Pöpper, Christina (editor); Strohmeier, Martin (editor)","2019","A large quantity of Mode S data is being gathered by the OpenSky receiver network every day. Information regarding common flight states, such as position, ground speed, and the vertical rate is broadcast by ADS-B and has already been decoded and made available for researchers via the OpenSky historical database. However, there is still a large amount of Mode S communication data that has not yet been fully explored. Specifically, the information contained in Enhanced Mode S Surveillance downlink messages can be utilized to better support ATM research. The challenge of decoding such information lies in the implicit inference process for Mode S Comm-B messages. This paper presents a new open library, pymodes-opensky, which connects the existing open-source pyModeS decoder to the raw Mode S messages from the OpenSky historical database through the Impala shell. It also presents a convenient workflow that can be used to obtain additional information regarding airspeeds, flight intentions, and meteorological conditions of a given flight from the OpenSky database. An analysis based on a global dataset from OpenSky is conducted, and the associated Mode S interrogation statistics in different regions are shown.","","en","conference paper","","","","","","","","","","Control & Operations","Control & Simulation","","",""
"uuid:e077325a-2a09-41f4-b2f1-4cd43bc66dc6","http://resolver.tudelft.nl/uuid:e077325a-2a09-41f4-b2f1-4cd43bc66dc6","Suppression of persistent photoconductivity AlGaN/GaN heterostructure photodetectors using pulsed heating","Sun, J. (TU Delft Electronic Components, Technology and Materials); Zhan, Teng (Chinese Academy of Sciences; State Key Laboratory of Solid State Lighting); Liu, Zewen (Tsinghua University); Wang, Junxi (Chinese Academy of Sciences; State Key Laboratory of Solid State Lighting); Yi, Xiaoyan (Chinese Academy of Sciences; State Key Laboratory of Solid State Lighting); Sarro, Pasqualina M (TU Delft Electronic Components, Technology and Materials); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials; State Key Laboratory of Solid State Lighting)","","2019","This paper demonstrates a method to reduce the decay time in AlGaN/GaN photodetectors by a pulsed heating mode. A suspended AlGaN/GaN heterostructure photodetector integrated with a micro-heater is fabricated and characterized under ultraviolet illumination. We have observed that the course of persistent photoconductivity was effectively accelerated by applying pulsed heating. The decay time is significantly reduced from 175 s by DC heating to 116 s by 50 Hz pulsed heating at the same power (280 mW). With the same pulse duty cycle and a 50 Hz pulsed heating frequency, a reduction of 30%-45% in decay time is measured compared to DC heating.","pulsed heating; AlGaN; GaN; UV detector","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.","","2021-08-02","","","Electronic Components, Technology and Materials","","",""
"uuid:cf3e4c2a-db2f-4230-b262-1235be8a92c7","http://resolver.tudelft.nl/uuid:cf3e4c2a-db2f-4230-b262-1235be8a92c7","Lumen Degradation Lifetime Prediction for High-Power White LEDs Based on the Gamma Process Model","Ibrahim, M.S. (The Hong Kong Polytechnic University); Fan, J. (TU Delft Electronic Components, Technology and Materials; Hohai University; Changzhou Institute of Technology Research for Solid State Lighting); Yung, Winco K.C. (The Hong Kong Polytechnic University); Wu, Zeyu (Beihang University); Sun, B. (Beihang University)","","2019","Nowadays, due to the advancement of design and manufacturing technology, there are many consumer products with high reliability. Similarly, the competition in the business sector influences the product development time to become shorter and that makes it difficult for manufacturers to evaluate the reliability of current products before new products are released to the market. This phenomenon is manifested in the lighting industry, especially for the high power white light-emitting diodes (LEDs) as these products have a long lifetime and high reliability. Currently, the standard to predict the lifetime of LEDs is based on a deterministic nonlinear least squares method which has low prediction accuracy. To overcome this, degradation models are being used to study the reliability of such products, considering the uncertainties and the quality characteristics whose degradation over a period of time can be related to the product lifetime. A stochastic approach based on gamma distributed degradation (GDD) is proposed in this study to estimate the long-term lumen degradation lifetime of phosphor-converted white LEDs. An accelerated thermal degradation test was designed to gather luminous flux degradation data which was analyzed based on maximum likelihood estimation (MLE) and the method of moments (MM) to estimate the parameters for the GDD model. The MLE method has shown superiority over MM in terms of the estimation of the model parameters due to its iterative algorithm being likely to find the optimal estimation. The lifetime prediction results show that the accuracy of the proposed method is much better than the TM-21 nonlinear least squares (NLS) approach which makes it promising for future industrial applications.","gamma distributed degradation (GDD); Light-emitting diodes (LEDs); luminous flux degradation; maximum likelihood estimation; method of moments.","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:1268b5aa-2f7e-4a91-9760-840ae5629209","http://resolver.tudelft.nl/uuid:1268b5aa-2f7e-4a91-9760-840ae5629209","Suspended tungsten trioxide (WO3) gate AlGaN/GaN heterostructure deep ultraviolet detectors with integrated micro-heater","Sun, J. (TU Delft Electronic Components, Technology and Materials); Zhan, Teng (Chinese Academy of Sciences; State Key Laboratory of Solid State Lighting); Liu, Zewen (Tsinghua University); Wang, Junxi (Chinese Academy of Sciences; State Key Laboratory of Solid State Lighting); Yi, Xiaoyan (Chinese Academy of Sciences; State Key Laboratory of Solid State Lighting); Sarro, Pasqualina M (TU Delft Electronic Components, Technology and Materials); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials; State Key Laboratory of Solid State Lighting)","","2019","A suspended WO3-gate AlGaN/GaN heterostructure photodetector integrated with a micro-heater is micro-fabricated and characterized for ultraviolet photo detection. The transient optical characteristics of the photodetector at different temperatures are studied. The 2DEG-based photodetector shows a recovery (170 s) time under 240 nm illumination at 150 ℃. The measured spectral response of WO3-gate AlGaN/GaN heterostructure shows a high response in deep ultraviolet range. Responsivity at 240 nm wavelength is 4600 A/W at 0.5 V bias. These characteristics support the feasibility of a high accuracy deep UV detector based on the suspended AlGaN/GaN heterostructure integrated with a micro-heater.","","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:f69dcab2-9a72-4ed7-aeb2-f3d4f8609e96","http://resolver.tudelft.nl/uuid:f69dcab2-9a72-4ed7-aeb2-f3d4f8609e96","A method for fast evaluation of potential consequences of dam breach","Ge, W. (TU Delft Safety and Security Science; Zhengzhou University); Jiao, Yutie (Zhengzhou University); Sun, Heqiang (Zhengzhou University); Li, Zongkun (Zhengzhou University); Zhang, Hexiang (Zhengzhou University); Zheng, Yan (Zhengzhou University); Guo, Xinyan (Zhengzhou University); Zhang, Zhaosheng (Henan Qianping Reservoir Construction Administration); van Gelder, P.H.A.J.M. (TU Delft Safety and Security Science)","","2019","Dam breach has catastrophic consequences for human lives and economy. In previous studies, empirical models are often, to a limited extent, due to the inadequacy of historical dam breach events. Physical models, which focus on simulating human behavior during floods, are not suitable for fast analysis of a large number of dams due to the complexities of many key parameters. Therefore, this paper proposes a method for fast evaluation of potential consequences of dam breach. Eight main indices, i.e., capacity of reservoir (CR), dam height (HD), population at risk (PR), economy at risk (ER), understanding of dam breach (UB), industry type (TI), warning time (TW), and building vulnerability (VB), are selected to establish an evaluation index system. A catastrophe evaluation method is introduced to establish an evaluation model for potential consequences of dam breach based on the indices which are divided into five grades according to the relevant standards and guidelines. Validation of the method by twelve historical dam breach events shows a good accuracy. The method is applied to evaluate potential consequences of dam breach of Jiangang Reservoir in Henan Province, China. It is estimated that loss of life in the worst scenario is between that of Hengjiang Reservoir and that of Shimantan Reservoir dam breach, of which fatalities are 941 and 2717, respectively, showing that risk management measures should be taken to reduce the risk of potential loss of life.","Catastrophe evaluation; Consequences; Dam breach; Economy; Life","en","journal article","","","","","","","","","","","Safety and Security Science","","",""
"uuid:f1d1b060-f7a9-44c7-84b4-739cb132fb9e","http://resolver.tudelft.nl/uuid:f1d1b060-f7a9-44c7-84b4-739cb132fb9e","High performance mixed potential type No2 gas sensor based on porous YSZ layer formed with graphite doping","Hong, Hao (Guizhou University); Sun, J. (TU Delft Electronic Components, Technology and Materials; China Research Institute); Wu, Cinan (Guizhou University); Liu, Zewen (Tsinghua University)","","2019","High performance mixed potential type NO2 sensors using porous yttria-stabilized zirconia (YSZ) layers doped with different concentration graphite as solid electrolyte and LaFeO3 as sensing electrode were fabricated and characterized. LaFeO3 was prepared by a typical citrate sol–gel method and characterized using XRD. The surface morphology and porosity of porous YSZ layers were characterized by field emission scanning electron microscope (FESEM). The sensor doped with 3 wt% graphite shows the highest response (−76.4 mV to 80 ppm NO2) and the response is linearly dependent on the logarithm of NO2 concentration in the range of 10–200 ppm. The sensor measurement results also present good repeatability and cross-sensitivity.","Graphite; Mixed potential; NO; Porous YSZ layers","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:76847a92-d407-4a8e-b26d-4660282134a5","http://resolver.tudelft.nl/uuid:76847a92-d407-4a8e-b26d-4660282134a5","A Reliability Prediction Methodology for LED Arrays","Sun, B. (Guangdong University of Technology); Fan, J. (Hohai University); Fan, Xuejun (Lamar University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Zhang, Guohao (Guangdong University of Technology)","","2019","In this paper, a physics of failure-based prediction method is combined with statistical models to consider the impact of current crowding and current droop effects on the reliability of LED arrays. Electronic-thermal models of LEDs are utilized to obtain the operation conditions under the influences of current crowding and current droop. A Markov chain-based model is used to calculate the probability distribution of each failure mode, including the lumen decay and catastrophic failure. Two types of LEDs were selected for a numerical study. The proposed prediction method provides the realistic reliability prediction results. It is found that the properties of LEDs have a great impact on their hazard rates of LED arrays. The equivalent resistance, third-order non-radiative coefficient, and radiative coefficient of LEDs are critical to the reliability of an LED array.","Catastrophic failure; electronic-thermal model; LED array; Markov chain; reliability prediction","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:a45d74a8-99b0-48c0-9343-4b6a755a1c72","http://resolver.tudelft.nl/uuid:a45d74a8-99b0-48c0-9343-4b6a755a1c72","Ultrafast Melting of Metal–Organic Frameworks for Advanced Nanophotonics","Kulachenkov, Nikita K. (ITMO University); Bruyere, Stéphanie (Lorraine University); Sapchenko, Sergey A. (The University of Manchester; Nikolaev Institute of Inorganic Chemistry SB RAS; Novosibirsk State University); Mezenov, Yuri A. (ITMO University); Sun, D. (TU Delft ChemE/Inorganic Systems Engineering); Krasilin, Andrei A. (ITMO University; Ioffe Institute); Nominé, Alexandre (ITMO University; Lorraine University); Pidko, E.A. (TU Delft ChemE/Inorganic Systems Engineering; TU Delft ChemE/Algemeen; ITMO University); Milichko, Valentin A. (ITMO University; Lorraine University)","","2019","The conversion of metal–organic frameworks (MOFs) into derivatives with a well-defined shape and composition is considered a reliable way to produce efficient catalysts and energy capacitors at the nanometer scale. Yet, approaches based on conventional melting of MOFs provide the derivatives such as amorphous carbon, metal oxides, or metallic nanoclusters with an appropriate morphology. Here ultrafast melting of MOFs is utilized by femtosecond laser pulses to produce a new generation of derivatives with complex morphology and enhanced nonlinear optical response. It is revealed that such a nonequilibrium process allows conversion of interpenetrated 3D MOFs comprising flexible ligands into well-organized spheres with a metal oxide dendrite core and amorphous organic shell. The ability to produce such derivatives with a complex morphology is directly dependent on the electronic structure, crystal density, ligand flexibility, and morphology of initial MOFs. An enhanced second harmonic generation and three-photon luminescence are also demonstrated due to the resonant interaction of 100–1000 nm spherical derivatives with light. The results obtained are in the favor of new approaches for melting special types of MOFs for nonlinear nanophotonics.","derivatives; femtosecond laser; metal–organic framework; nanophotonics; ultrafast melting","en","journal article","","","","","","","","2020-12-20","","","ChemE/Inorganic Systems Engineering","","",""
"uuid:633ecf01-8d29-4756-9ef7-6f6f465daa9d","http://resolver.tudelft.nl/uuid:633ecf01-8d29-4756-9ef7-6f6f465daa9d","Unveiling the Structure Sensitivity for Direct Conversion of Syngas to C2-Oxygenates with a Multicomponent-Promoted Rh Catalyst","Sun, X. (TU Delft ChemE/Catalysis Engineering); Jansma, H. (TU Delft ChemE/O&O groep; TU Delft ChemE/Catalysis Engineering); Miyama, Toshihito (Sekisui Chemical Co., LTD., Tsukubashi); Sanjeewa Aluthge, Rasika Dasanayake (Sekisui Chemical Co., LTD., Tsukubashi); Shinmei, Kenichi (Sekisui Chemical Co., LTD., Tsukubashi); Yagihashi, Noritoshi (Sekisui Chemical Co., LTD., Tsukubashi); Nishiyama, Haruka (Sekisui Chemical Co., LTD., Tsukubashi); Osadchii, D. (TU Delft ChemE/Catalysis Engineering); van der Linden, B. (TU Delft ChemE/O&O groep; TU Delft ChemE/Catalysis Engineering); Makkee, M. (TU Delft ChemE/Catalysis Engineering)","","2019","Abstract: Mn and Li promoted Rh catalysts supported on SiO2 with a thin TiO2 layer were synthesized by stepwise incipient wetness impregnation approach. The thin TiO2 layer on the surface of SiO2 was proved to stabilize those small Rh nanoparticles and hinder their agglomeration. The reducibility of Rh on these catalysts depends on Rh particle size as well as the position of manganese oxide, and large Rh nanoparticles with MnO on Rh nanoparticles can be only reduced at an elevated temperature. Catalyst with large Rh particles exhibits a higher CO conversion and higher products selectivity towards long chain hydrocarbons and C2-oxygenates at the expense of decreasing methane formation than a similar catalyst with smaller Rh particles. This was attributed to the synergistic effect of Mn and Li promotion and molar ratio between Rh0 and Rhδ+ sites on the surface of Rh nanoparticles. Moreover, Rh nanoparticles on MnO are proved to be more efficient in promoting hydrogenation of acetaldehyde to ethanol than its counterpart with MnO on Rh nanoparticles. Finally, in order to target high C2-oxygenates selectivity, low reaction temperature together with a low H2/CO ratio in the feed is recommended. Graphic Abstract: [Figure not available: see fulltext.].","Acetaldehyde; Ethanol; Mn; Particle size; Rh","en","journal article","","","","","","","","","","","ChemE/Catalysis Engineering","","",""
"uuid:ea241a32-56c8-4623-8ea9-762c7022f76a","http://resolver.tudelft.nl/uuid:ea241a32-56c8-4623-8ea9-762c7022f76a","Stress analysis of pressure-assisted sintering for the double-side assembly of power module","Liu, Y. (TU Delft Electronic Components, Technology and Materials; Harbin University of Science and Technology); Zhang, H. (TU Delft Electronic Components, Technology and Materials; Harbin University of Science and Technology); Wang, Lingen (Boschman Technologies); Fan, Xuejun (Lamar University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Sun, Fenglian (Harbin University of Science and Technology)","","2019","Purpose: Crack and stress distribution on dies are key issues for the pressure-assisted sintering bonding of power modules. The purpose of this research is to build a relationship among stress distributions, sintering sequences and sintering pressures during the sintering processes. Design/methodology/approach: Three sintering sequences, S(a), S(b) and S(c), have been designed for the double-side assembly of power module in this paper. Experiments and finite element method (FEM) analysis are conducted to investigate the crack and stress distribution. Findings: The sintering sequence had significant effects on the crack generation in the chips during the sintering process under 30-MPa pressure. The simulation results revealed that the module sintered by S(a) showed lower chip stress than those by the other two sintering sequences under 30 MPa. In contrast, the chip stress is the highest when the sintering sequence follows S(b). The simulation results explained the crack generation and prolongation in the experiments. S(a) was recommended as the best sintering sequence because of the lowest chip stress and highest yield rate. Originality/value: This study investigated the stress distributions of the double-side sintered power modules under different sintering pressures. Based on the results of experiments and FEM analysis, the best sintering sequence design is provided under various sintering pressures.","Double-side assembly; Power chip; Reliability; Sintering","en","journal article","","","","","","Accepted author manuscript","","","","","Electronic Components, Technology and Materials","","",""
"uuid:895b3a1d-2431-48a1-99ae-1d564e8978c3","http://resolver.tudelft.nl/uuid:895b3a1d-2431-48a1-99ae-1d564e8978c3","Assessment of Flexural Behavior of Pultruded GFRP Laminates for Bridge Deck Applications","Zhang, Youyou (University of California); Mosallam, Ayman (University of California); Liu, Yuqing (Tongji University); Sun, Yun (Tongji University); Xin, H. (TU Delft Steel & Composite Structures); He, Jun (Changsha University of Science and Technology)","","2019","In this study, flexural behaviors of the pultruded composite laminate were evaluated through experiments and theoretical analysis. Three-point flexural tests were performed for pultruded specimens. The typical failure mode for the longitudinal flexural specimens was local crush on the top surface accompanied with local cracks on the bottom surface at midspan. For the transverse tests, the specimens presented a failure pattern with local cracks initiated and propagated at both the top and bottom sides at the midspan. Theoretical analysis, based on micromechanics and macromechanics, was performed to predict flexural deformation and stress distribution of the pultruded laminate beam. Based on the continuum damage model proposed by the authors, this paper mainly investigates the flexural behavior and failure pattern of pultruded lamination. The theoretical and finite element results agreed well with the test results. The results can provide a reference for the design of the structural pultruded modular systems.","","en","journal article","","","","","","","","","","","Steel & Composite Structures","","",""
"uuid:13629b38-b93f-42a4-8d4e-e2e158270115","http://resolver.tudelft.nl/uuid:13629b38-b93f-42a4-8d4e-e2e158270115","Integrating multi-functional space and long-span structure in the early design stage of indoor sports arenas by using parametric modelling and multi-objective optimization","Pan, W. (TU Delft Design Informatics; South China University of Technology); Turrin, M. (TU Delft Design Informatics); Louter, P.C. (TU Delft OLD Structural Design); Sariyildiz, I.S. (TU Delft Design Informatics); Sun, Yimin (South China University of Technology)","","2019","Indoor multi-functional sports arenas are a complex building type. Integration of the (multi-) functional space and of the large-span structure of the roof mainly determines the overall geometry of the building, and is one of the most challenging phases of the design. Several interdisciplinary numeric assessments and numerous solutions with diverse geometries (rather than just several specific types) should be considered to make informed design decisions. To support the design exploration in the early design stage for multi-functional arenas, this paper proposes a design process that is composed of a flexible parametric model, a framework of interdisciplinary assessment criteria, and multi-objective optimization (MOO) with post-process tools. The parametric model is defined based on the basic spatial composition of arenas and is flexible to provide a broader design space, including diverse solutions with three frequently-used structural types. The framework of assessment criteria includes indicators of viewing quality for spectators, acoustics, and structures, which can evaluate the design in different aspects. Based on certain assessment criteria, the MOO can be used to search for good designs in the broader space, and the post-process tools facilitate the designer to analyse the results. Two typical arenas (the Barclay Centre and the O2 Arena) are selected as real case studies to demonstrate the proposed process and assess the capacity. Results of the case studies validate the efficacy of the process and the necessity of the broader design space to include diverse solutions with multiple structural types.","Indoor sports arena; Long-span structure; Multi-functional space; Multi-objective optimization; Parametric modelling","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-07-11","","","Design Informatics","","",""
"uuid:303371c0-6e5d-460b-8ead-4a4b37b88d80","http://resolver.tudelft.nl/uuid:303371c0-6e5d-460b-8ead-4a4b37b88d80","Using GRACE to Explain Variations in the Earth's Oblateness","Sun, Y. (TU Delft Physical and Space Geodesy; Fuzhou University); Riva, R.E.M. (TU Delft Physical and Space Geodesy); Ditmar, P.G. (TU Delft Physical and Space Geodesy); Rietbroek, Roelof (Universität Bonn)","","2019","We present a new approach to estimate time variations in J2. Those variations are represented as the sum of contributions from individual sources. This approach uses solely Gravity Recovery And Climate Experiment (GRACE) data and the geoid fingerprints of mass redistributions that take place both at the surface and in the interior of the solid Earth. The results agree remarkably well with those based on satellite laser ranging, while estimates of the sources explain the observed variations in J2. Seasonal variations are dominated by terrestrial water storage and by mass redistribution in the atmosphere and ocean. Trends, however, are primarily controlled by the Greenland and Antarctic ice sheets and by glacial isostatic adjustment. The positive trend from surface mass variations is larger than the negative trend due to glacial isostatic adjustment and leads to an overall rising trend during the GRACE period (2002–2017).","C; Earth's dynamic oblateness; geoid fingerprints; GRACE; J; mass redistribution; J(2); C-20","en","journal article","","","","","","","","","","","Physical and Space Geodesy","","",""
"uuid:b50798d7-2f8a-4aeb-8911-72d5219990bc","http://resolver.tudelft.nl/uuid:b50798d7-2f8a-4aeb-8911-72d5219990bc","Carbon deposition in porous nickel/yttria-stabilized zirconia anode under methane atmosphere","Chen, Z. (TU Delft (OLD) MSE-3; University of Science and Technology Beijing); Wang, Li jun (University of Science and Technology Beijing); Du, Xiao jia (Suzhou Huatsing Jingkun New Energy Technology Co.); Sun, Zai hong (Suzhou Huatsing Jingkun New Energy Technology Co.); Li, Fu shen (University of Science and Technology Beijing); Chou, Kuo Chih (University of Science and Technology Beijing)","","2019","A commercial solid oxide fuel cell with a Ni/YSZ anode was characterized under a pure methane atmosphere. The amount of deposited carbon increased with an increase in temperature but decreased when the temperature exceeded 700°C. The reactivity of carbon decreased with increasing deposition temperature. Filamentous carbon was deposited from 400 to 600°C, whereas flake carbon was deposited at 700 and 800°C. With increasing temperature, the intensity ratio of the D band over the sum of the G and D bands was constant at the beginning and then decreased with the transformation of the carbon morphology. The crystallite size increased from 2.9 to 13 nm with increasing temperature. The results also indicated that the structure of the deposited carbon was better ordered with increasing deposition temperature. In comparison with pure Ni powders, the interaction between the YSZ substrate and Ni particles could not only modify the carbon deposition kinetics but also reduce the temperature effect on the structure and reactivity variation of carbon.","anode; coking; hydrocarbon fuel; Raman spectrum; solid oxide fuel cell","en","journal article","","","","","","Accepted Author Manuscript","","2020-03-08","","","(OLD) MSE-3","","",""
"uuid:46eca6fd-93dd-450e-a52d-6bc220a42741","http://resolver.tudelft.nl/uuid:46eca6fd-93dd-450e-a52d-6bc220a42741","Analytical solution of a mass-spring system containing shape memory alloys: Effects of nonlinearity and hysteresis","Zhuo, M. (TU Delft Applied Mechanics; The Hong Kong University of Science and Technology); Xia, Minglu (The Hong Kong University of Science and Technology); Sun, Qingping (The Hong Kong University of Science and Technology)","","2019","Nonlinear dynamics of vibration systems containing NiTi shape memory alloy (SMA) bars has long been obscured by the lack of an analytical solution, like the analytical solution for duffing equation. The problem results from the nonlinear and hysteretic restoring force of the SMA bar. Here we use a piecewise linear hysteretic model to describe the force-displacement relation of the SMA bar and use the averaging method to solve the equation of motion. We thus obtain an approximate analytical solution of the steady-state response of an SMA mass-spring system. The analytical solution can describe both stable and unstable behaviors of the vibration system and therefore offer a comprehensive understanding of the nonlinear responses. It is shown that the phase transition induced softening nonlinearity bends the frequency response curve (FRC) to the left, while the subsequent rehardening of martensite further bends the FRC to the right, leading to multi-valued regions and jump phenomena. The hysteresis is found to have little influence on the bending but it can significantly suppress the response amplitude. Comparison of the analytical results with experimental data validates the piecewise linear hysteretic model and the analytical solutions. This work provides a theoretical tool for design and vibration control of SMA mass-spring systems.","Hysteresis; Mass-spring system; NiTi shape memory alloy; Nonlinear vibration; Phase transition; Piecewise linear hysteretic model","en","journal article","","","","","","Accepted Author Manuscript","","2021-05-28","","","Applied Mechanics","","",""
"uuid:1b2f5e3a-ea21-4c5e-9d3f-de4a867c2b97","http://resolver.tudelft.nl/uuid:1b2f5e3a-ea21-4c5e-9d3f-de4a867c2b97","Multicolor Organometallic Mechanophores for Polymer Imaging Driven by Exciplex Level Interactions","Filonenko, G.A. (TU Delft ChemE/Inorganic Systems Engineering); Sun, D. (TU Delft ChemE/Inorganic Systems Engineering); Weber, Manuela (Freie Universität Berlin); Müller, Christian (Freie Universität Berlin); Pidko, E.A. (TU Delft ChemE/Inorganic Systems Engineering; TU Delft ChemE/Algemeen; ITMO University)","","2019","Photoluminescent compounds can undergo various structural changes upon interaction with light. When these changes manifest themselves in the excited state, the resulting emitters can obtain a sensory function. In this work, we designed coordination compounds that can vary their emission color in response to thermal and mechanical stimuli. When embedded in a polymer matrix, Cu-NHC sensors act as mechanophores, and their color-based response can readily describe mechanical stress and phase transition phenomena. A strong practical advantage of new mechanophores over previous generations of organometallic stress sensors stems from their reliance on emission color variations that are easy to detect. In a broad context, our work implies that emission color variations that we often view as thermally governed can also be triggered mechanically and used to generate sensory information.","","en","journal article","","","","","","","","","","","ChemE/Inorganic Systems Engineering","","",""
"uuid:9e5de706-0275-46b3-b074-aa291b9247d7","http://resolver.tudelft.nl/uuid:9e5de706-0275-46b3-b074-aa291b9247d7","Structure-activity relationships in metal organic framework derived mesoporous nitrogen-doped carbon containing atomically dispersed iron sites for CO2 electrochemical reduction","Sun, X. (TU Delft ChemE/Catalysis Engineering); Wang, R. (TU Delft ChemE/Catalysis Engineering); Ould-Chikh, Samy (King Abdullah University of Science and Technology); Osadchii, D. (TU Delft ChemE/Catalysis Engineering); Li, G. (TU Delft ChemE/Inorganic Systems Engineering; TU Delft ChemE/Catalysis Engineering); Aguilar, Antonio (Université Grenoble Alpes); Hazemann, Jean louis (Université Grenoble Alpes); Kapteijn, F. (TU Delft ChemE/Catalysis Engineering); Gascon, Jorge (TU Delft ChemE/Catalysis Engineering; King Abdullah University of Science and Technology)","","2019","Mesoporous nitrogen-doped carbon nanoparticles with atomically dispersed iron sites (named mesoNC-Fe) are synthesized via high-temperature pyrolysis of an Fe containing ZIF-8 MOF. Hydrolysis of tetramethyl orthosilicate (TMOS) in the MOF framework prior to pyrolysis plays an essential role in maintaining a high surface area during the formation of the carbon structure, impeding the formation of iron (oxide) nanoparticles. To gain inside on the nature of the resulting atomically dispersed Fe moieties, HERFD-XANES, EXAFS and valence-to-core X-ray emission spectroscopies have been used. The experimental spectra (both XAS and XES) combined with theoretical calculations suggest that iron has a coordination sphere including a porphyrinic environment and OH/H2O moieties responsible for the high activity in CO2 electroreduction. DFT calculations demonstrate that CO formation is favored in these structures because the free energy barriers of *COOH formation are decreased and the adsorption of *H is impeded. The combination of such a unique coordination environment with a high surface area in the carbon structure of mesoNC-Fe makes more active sites accessible during catalysis and promotes CO2 electroreduction.","Atomically dispersed sites; CO; Electroreduction; Iron","en","journal article","","","","","","Accepted Author Manuscript","","2021-09-25","","","ChemE/Catalysis Engineering","","",""
"uuid:fa631c59-c4f0-4a16-99ab-46b1a66e68f9","http://resolver.tudelft.nl/uuid:fa631c59-c4f0-4a16-99ab-46b1a66e68f9","Chemical and rheological properties of polymer modified bitumen incorporating bio-oil derived from waste cooking oil","Sun, Z. (TU Delft Pavement Engineering; Harbin Institute of Technology); Yi, Junyan (Harbin Institute of Technology); Chen, Zining (Harbin Institute of Technology); Xie, Sainan (Harbin Institute of Technology); Xu, Meng (Harbin Institute of Technology); Feng, Decheng (Harbin Institute of Technology)","","2019","The chemical and rheological properties of polymer modified bitumen incorporating bio-oil derived from waste cooking oil (WCO) were investigated in this paper. At first, the chemical composition and mixing mechanism of the experimental materials were analysed from the perspective of functional group, and the influence of bio-oil on the activation energy was also researched. Then, the effect of bio-oil on the rotational viscosities of polymer modified bitumen and construction temperatures of corresponding mixtures was studied. Finally, the shear and bending rheological properties of polymer modified bitumen containing bio-oil were investigated. The results show that the bio-oil and styrene–butadiene–styrene (SBS) modified bitumen is mainly physically mixed, the addition of bio-oil decreases the activation energy of SBS modified bitumen. Additionally, the SBS modified bitumen containing bio-oil has lower viscosity values, and corresponding mixtures also have lower construction temperatures. Furthermore, the addition of bio-oil in SBS modified bitumen reduces the shear modulus and increases the bending creep compliance, which means bio-oil has positive effect on the low-temperature thermal cracking resistance performance while sacrificing the high-temperature rutting resistance performance to some extent. Therefore, the incorporation of WCO-based bio-oil in polymer modified bitumen is a promising technique to be used in cold regions where the low-temperature problems are more crucial.","Bio-oil; Chemo-rheological property; Huet–such model; Polymer modified bitumen; Waste cooking oil","en","journal article","","","","","","Accepted Author Manuscript","","2020-10-08","","","Pavement Engineering","","",""
"uuid:b25b3734-fa33-4370-bab9-3b2cb1348728","http://resolver.tudelft.nl/uuid:b25b3734-fa33-4370-bab9-3b2cb1348728","Modeling and Analyzing Impacts of Drifting Anisotropic Ionospheric Irregularities on Inclined Geosynchronous SAR","Dong, Xichao (Beijing Institute of Technology); Hu, Jiaqi (Beijing Institute of Technology); Hu, Cheng (Beijing Institute of Technology); Li, Y. (TU Delft Mathematical Geodesy and Positioning); Sun, Shiyu (Beijing Institute of Technology)","","2019","The sub-satellite track of geosynchronous synthetic aperture radar (GEO SAR) presents the figure ""8"" or ""O"", which causes the great changes of platform motion direction and the different projection of anisotropic irregularities along the line-of-sight (LOS) direction. Due to the almost equal angle velocity to that of Earth, the GEO SAR has smaller ionospheric penetration point (IPP) scanning velocity which is much smaller to the counterpart of the low earth orbit SAR (LEO SAR) while is comparable to the drifting velocity of irregularities, which will affect the effective azimuthal velocity. These facts lead to the consequence that the satellite signals from the GEO SAR would become more vulnerable when they are transmitted in the environment where the ionospheric scintillation occurs. However, few works are focused on these mentioned issues towards the GEO SAR system. In this paper, the impacts of ionospheric scintillation on GEO SAR imaging will be analyzed considering the anisotropy and drifting velocity of irregularities. The anisotropy and drifting velocity effects can both originate from the effect on power spectral density (PSD) of phase screen which is used to model the ionospheric scintillation effects. Based on the data from international geomagnetic reference field (IGRF) and satellite tool kit (STK), the GEO SAR imaging simulations for different GEO SAR orbital configurations and positions are carried out. The simulation results demonstrate that the anisotropy and the drifting velocity of irregularities will cause the changes of stripe direction and affect the quality of GEO SAR images.","Anisotropy; drifting velocity; geosynchronous synthetic aperture radar (GEO SAR); ionospheric scintillation","en","journal article","","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:6db72bfd-c8a5-4cc3-a639-20768c8a0863","http://resolver.tudelft.nl/uuid:6db72bfd-c8a5-4cc3-a639-20768c8a0863","Review of the recent progress on GaN-based vertical power Schottky barrier diodes (SBDs)","Sun, Y. (TU Delft Electronic Components, Technology and Materials); Kang, Xuanwu (Chinese Academy of Sciences); Zheng, Yingkui (Chinese Academy of Sciences); Lu, Jiang (Chinese Academy of Sciences); Tian, Xiaoli (Chinese Academy of Sciences); Wei, Ke (Chinese Academy of Sciences); Wu, Hao (Chinese Academy of Sciences); Wang, Wenbo; Liu, Xinyu (Chinese Academy of Sciences); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2019","Gallium nitride (GaN)-based vertical power Schottky barrier diode (SBD) has demonstrated outstanding features in high-frequency and high-power applications. This paper reviews recent progress on GaN-based vertical power SBDs, including the following sections. First, the benchmark for GaN vertical SBDs with different substrates (Si, sapphire, and GaN) are presented. Then, the latest progress in the edge terminal techniques are discussed. Finally, a typical fabrication flow of vertical GaN SBDs is also illustrated briefly.","Edge termination techniques; GaN; Schottky barrier diode (SBD); Vertical power devices","en","review","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:a51238d7-bc34-43f8-b6a1-a76869c59e95","http://resolver.tudelft.nl/uuid:a51238d7-bc34-43f8-b6a1-a76869c59e95","The spatial distribution and frequency of street, plot and building types across five European cities","Berghauser Pont, Meta (Chalmers University of Technology); Stavroulaki, Gianna (Chalmers University of Technology); Gil, Jorge (Chalmers University of Technology); Marcus, Lars (Chalmers University of Technology); Olsson, Jesper (University of Gothenburg); Sun, Kailun (Chalmers University of Technology); Serra, Miguel (Universidade do Porto); Hausleitner, B. (TU Delft OLD Urban Compositions); Dhanani, Ashley (UCL Bartlett School of Planning); Legeby, Ann (KTH Royal Institute of Technology)","","2019","Typologies have always played an important role in urban planning and design practice and formal studies have been central to the field of urban morphology. These studies have predominantly been of a historical-qualitative nature and do not support quantitative comparisons between urban areas and between different cities, nor offer the precise and comprehensive descriptions needed by those engaged in urban planning and design practice. To describe contemporary urban forms, which are more diffuse and often elude previous historic typologies, systematic quantitative methods can be useful but, until recently, these have played a limited role in typo-morphological studies. This paper contributes to recent developments in this field by integrating multi-variable geometric descriptions with inter-scalar relational descriptions of urban form. It presents typologies for three key elements of urban form (streets, plots and buildings) in five European cities, produced using statistical clustering methods. In a first instance, the resulting typologies contribute to a better understanding of the characteristics of streets, plots and buildings. In particular, the results offer insight into patterns between the types (i.e. which types are found in combination and which not) and provide a new large scale comparative analysis across five European cities. To conclude, a link between quantitative analysis and theory is established, by testing two well-known theoretical propositions in urban morphology: the concept of the burgage cycle and the theory of natural movement.","built density; cluster analysis; land division; network centrality; Typo-morphology","en","journal article","","","","","","Accepted Author Manuscript","","","","","OLD Urban Compositions","","",""
"uuid:958ca590-cc08-498b-9c73-a5e20e589355","http://resolver.tudelft.nl/uuid:958ca590-cc08-498b-9c73-a5e20e589355","Using Vine Copulas to Generate Representative System States for Machine Learning","Konstantelos, Ioannis (Imperial College London); Sun, Mingyang (Imperial College London); Tindemans, Simon H. (TU Delft Intelligent Electrical Power Grids); Issad, Samir (Reseau de Transport d'Electricite); Panciatici, Patrick (Reseau de Transport d'Electricite); Strbac, Goran (Imperial College London)","","2019","The increasing uncertainty that surrounds electricity system operation renders security assessment a highly challenging task; the range of possible operating states expands, rendering traditional approaches based on heuristic practices and ad hoc analysis obsolete. In turn, machine learning can be used to construct surrogate models approximating the system's security boundary in the region of operation. To this end, past system history can be useful for generating anticipated system states suitable for training. However, inferring the underlying data model, to allow high-density sampling, is problematic due to the large number of variables, their complex marginal probability distributions and the nonlinear dependence structure they exhibit. In this paper, we adopt the C-Vine pair-copula decomposition scheme; clustering and principal component transformation stages are introduced, followed by a truncation to the pairwise dependency modeling, enabling efficient fitting and sampling of large datasets. Using measurements from the French grid, we show that a machine learning training database sampled from the proposed method can produce binary security classifiers with superior predictive capability compared to other approaches.","Copulas; data clustering; machine learning; Monte Carlo simulation; parametric statistics; principal component analysis; risk assessment; stochastic dependence; uncertainty analysis","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-07-01","","","Intelligent Electrical Power Grids","","",""
"uuid:c79ea245-ea8f-4fad-a242-0e0db3b17a35","http://resolver.tudelft.nl/uuid:c79ea245-ea8f-4fad-a242-0e0db3b17a35","Fibre-bridged fatigue delamination in multidirectional composite laminates","Yao, Liaojun (Harbin Institute of Technology); Cui, Hao (Cranfield University); Sun, Yi (Harbin Institute of Technology); Guo, Licheng (Harbin Institute of Technology); Chen, Xiangming (Aircraft Strength Research Institute); Zhao, Meiying (Northwestern Polytechnical University); Alderliesten, R.C. (TU Delft Structural Integrity & Composites)","","2018","The influence of fibre bridging on delamination failure in multidirectional composite laminates with different thickness scales is characterized, and the dependence of fibre bridging significance on laminate thickness as well as loading regime is investigated in this paper. Both quasi-static and fatigue resistance curves (R-curve) are experimentally determined to quantify the significance of fibre bridging in delamination growth. The results clearly demonstrate that thickness has effect on the amount of fibre bridging in quasi-static delamination. And the significance of fibre bridging decreases with the increase in laminate thickness. However, the situation for fatigue delamination growth (FDG) is much more complicated. The difference in fibre bridging generation seems to be insignificant in short fatigue cracks and at the plateau state, whereas more bridging fibres can be present in a thinner laminate in-between state. Loading regimes also have significant effect on the amount of fibre bridging. The results clearly demonstrate that more bridging fibres can be generated in quasi-static delamination compared to fatigue. A modified Paris relation proposed by the authors in previous studies is employed in present study to determine fibre-bridged FDG behaviors in multidirectional composite laminates with various thickness scales. All fatigue data locate in a relatively narrow band region of the resistance graph, resulting in a master resistance curve in determining fatigue delamination behaviors. This clearly demonstrates that neither thickness nor fibre bridging has significant effect on fatigue delamination behaviors, if the similarity is well represented.","A. Polymer-matrix composites (PMCs); B. Delamination; B. Fatigue; Multidirectional","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-04-01","","","Structural Integrity & Composites","","",""
"uuid:2269344a-cdfd-4325-9f36-d70a50883f57","http://resolver.tudelft.nl/uuid:2269344a-cdfd-4325-9f36-d70a50883f57","Quantifying the single-scattering albedo for the January 2017 Chile wildfires from simulations of the OMI absorbing aerosol index","Sun, J. (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI)); Veefkind, j. Pepijn (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI)); Van Velthoven, Peter (Royal Netherlands Meteorological Institute (KNMI)); Levelt, Pieternel Felicitas (TU Delft Atmospheric Remote Sensing; Royal Netherlands Meteorological Institute (KNMI))","","2018","The absorbing aerosol index (AAI) is a qualitative parameter directly calculated from satellite-measured reflectance. Its sensitivity to absorbing aerosols in combination with a long-term data record since 1978 makes it an important parameter for climate research. In this study, we attempt to quantify aerosol absorption by retrieving the single-scattering albedo (ω0) at 550 nm from the satellite-measured AAI. In the first part of this study, AAI sensitivity studies are presented exclusively for biomass-burning aerosols. Later on, we employ a radiative transfer model (DISAMAR) to simulate the AAI measured by the Ozone Monitoring Instrument (OMI) in order to derive ω0 at 550 nm. Inputs for the radiative transfer calculations include satellite measurement geometry and surface conditions from OMI, aerosol optical thickness (τ) from the Moderate Resolution Imaging Spectroradiometer (MODIS) and aerosol microphysical parameters from the AErosol RObotic NETwork (AERONET), respectively. This approach is applied to the Chile wildfires for the period from 26 to 30 January 2017, when the OMI-observed AAI of this event reached its peak. The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) overpasses missed the evolution of the smoke plume over the research region; therefore the aerosol profile is parameterized. The simulated plume is at an altitude of 4.5-4.9 km, which is in good agreement with available CALIOP backscatter coefficient measurements. The data may contain pixels outside the plume, so an outlier detection criterion is applied. The results show that the AAI simulated by DISAMAR is consistent with satellite observations. The correlation coefficients fall into the range between 0.85 and 0.95. The retrieved mean ω0 at 550 nm for the entire plume over the research period from 26 to 30 January 2017 varies from 0.81 to 0.87, whereas the nearest AERONET station reported ω0 between 0.89 and 0.92. The difference in geolocation between the AERONET site and the plume, the assumption of homogeneous plume properties, the lack of the aerosol profile information and the uncertainties in the inputs for radiative transfer calculation are primarily responsible for this discrepancy in ω0.","","en","journal article","","","","","","","","","","","Atmospheric Remote Sensing","","",""
"uuid:989ce975-a30f-4e8d-8c19-a5938d957ced","http://resolver.tudelft.nl/uuid:989ce975-a30f-4e8d-8c19-a5938d957ced","Preparation of bio-bitumen by bio-oil based on free radical polymerization and production process optimization","Sun, Z. (TU Delft Pavement Engineering; Harbin Institute of Technology); Yi, Junyan (Harbin Institute of Technology); Feng, Decheng (Harbin Institute of Technology); Kasbergen, C. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering); Zhu, Yiming (Harbin Institute of Technology)","","2018","Bio-oil produced during the production of biodiesel is a burden to the environment. Recycling and utilization of bio-oil as a substitute for pavement bitumen can help to build an environmentally-friendly and clean infrastructure. In this study, the bio-bitumen was prepared by bio-oil based on free radical polymerization. Different kinds of bio-bitumen products were produced by reacting bio-oil with an initiator and an accelerator solution at different reaction conditions. The orthogonal experimental method was employed to determine the optimal bio-bitumen production process by evaluating the indices of viscosity, rutting factors and fatigue factors. The test results show that the optimal mass proportions of bio-oil:initiator:accelerator solution is 100:1:2. Materials with these mass proportions should react at 100 °C for 2 h to yield the best bio-bitumen product. This kind of bio-bitumen product can be considered as a promising substitute for traditional petroleum bitumen.","Bio-bitumen; Bio-oil; Free radical polymerization; Production process optimization; Waste cooking oil","en","journal article","","","","","","","","2020-04-12","","","Pavement Engineering","","",""
"uuid:9250a4c4-194e-4da4-8d4c-7d42d99ffb0c","http://resolver.tudelft.nl/uuid:9250a4c4-194e-4da4-8d4c-7d42d99ffb0c","Thickness effects on fibre-bridged fatigue delamination growth in composites","Yao, L. (TU Delft Structural Integrity & Composites; Harbin Institute of Technology); Cui, Hao (Cranfield University); Alderliesten, R.C. (TU Delft Structural Integrity & Composites); Sun, Yi (Harbin Institute of Technology); Guo, Licheng (Harbin Institute of Technology)","","2018","This paper provides an investigation on thickness effects on fibre-bridged fatigue delamination growth (FDG) in composite laminates. A modified Paris relation was employed to interpret experimental fatigue data. The results clearly demonstrated that both thickness and fibre bridging had negligible effects on FDG behaviors. Both energy principles and fractography analysis were subsequently performed to explore the physical reasons of this independence. It was found that the amount of energy release of a given crack growth was not only independent of fibre bridging, but also thickness. Fibre print was the dominant microscopic feature located on fracture surfaces, physically making the same energy dissipation during FDG. Furthermore, the present study provides extra evidence on the importance of using an appropriate similitude parameter in FDG studies. Particularly, the strain energy release rate (SERR) range applied around crack front was demonstrated as an appropriate similitude parameter for fibre-bridged FDG study.","A. Polymer-matrix composites (PMCs); B. Delamination; B. Fatigue; Fibre bridging","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.","","2018-11-01","","","Structural Integrity & Composites","","",""
"uuid:ac299084-f546-480b-ac9b-16a0edf07b13","http://resolver.tudelft.nl/uuid:ac299084-f546-480b-ac9b-16a0edf07b13","Three-dimensional receiver deghosting of seismic streamer data using L1 inversion and redundant extended radon dictionary","Sun, Yimin (Aramco Overseas Company B.V.); Verschuur, D.J. (TU Delft ImPhys/Acoustical Wavefield Imaging)","","2018","In this paper, we propose a novel three-dimensional receiver deghosting algorithm that is capable of deghosting both horizontal and slanted streamer data in a theoretically consistent manner. Our algorithm honours wave propagation phenomena in a true three-dimensional sense and frames the three-dimensional receiver deghosting problem as a Lasso problem. The ultimate goal is to minimise the mismatch between the actual measurements and the simulated wavefield with an L1 constraint applied in
the extended Radon space to handle the underdetermined nature of this problem. We successfully demonstrate our algorithm on a modified three-dimensional EAGE/SEG
Overthrust model and a Red Sea marine dataset.","Data processing; Deghosting; Inversion","en","journal article","","","","","","","","","","","ImPhys/Acoustical Wavefield Imaging","","",""
"uuid:edbcde5f-0ec6-4683-9fcd-891500d198a8","http://resolver.tudelft.nl/uuid:edbcde5f-0ec6-4683-9fcd-891500d198a8","Metal-Organic-Framework-Mediated Nitrogen-Doped Carbon for CO2 Electrochemical Reduction","Wang, R. (TU Delft ChemE/Catalysis Engineering); Sun, X. (TU Delft ChemE/Catalysis Engineering); Ould-Chikh, Samy (King Abdullah University of Science and Technology); Osadchii, D. (TU Delft ChemE/Catalysis Engineering); Bai, F. (TU Delft ChemE/Catalysis Engineering; TU Delft Applied Sciences); Kapteijn, F. (TU Delft ChemE/Catalysis Engineering); Gascon, Jorge (TU Delft ChemE/Catalysis Engineering; King Abdullah University of Science and Technology)","","2018","A nitrogen-doped carbon was synthesized through the pyrolysis of the well-known metal-organic framework ZIF-8, followed by a subsequent acid treatment, and has been applied as a catalyst in the electrochemical reduction of carbon dioxide. The resulting electrode shows Faradaic efficiencies to carbon monoxide as high as ∼78%, with hydrogen being the only byproduct. The pyrolysis temperature determines the amount and the accessibility of N species in the carbon electrode, in which pyridinic-N and quaternary-N species play key roles in the selective formation of carbon monoxide.","CO electrochemical reduction; electrocatalyst; MOF-mediated synthesis; nitrogen-doped carbon; ZIF-8","en","journal article","","","","","","Accepted Author Manuscript","","2019-05-18","Applied Sciences","","ChemE/Catalysis Engineering","","",""
"uuid:7af4bfb6-ed83-4ff0-bcb0-b0820c479347","http://resolver.tudelft.nl/uuid:7af4bfb6-ed83-4ff0-bcb0-b0820c479347","Visualized study of thermochemistry assisted steam flooding to improve oil recovery in heavy oil reservoir with glass micromodels","Lyu, X. (TU Delft Reservoir Engineering; China University of Petroleum - Beijing); Liu, Huiqing (China University of Petroleum - Beijing); Pang, Zhanxi (China University of Petroleum - Beijing); Sun, Zhixue (China University of Petroleum (East China))","","2018","Steam channeling, one serious problem in the process of steam flooding in heavy oil reservoir, decreases the sweep efficiency of steam to cause a lower oil recovery. Viscosity reducer and nitrogen foam, two effective methods to improve oil recovery with different mechanism, present a satisfactory result after steam flooding. In this article, a 2D visualized device was introduced to investigate the synergistic development effect of two different chemical additives and intuitively study their flowing characteristic in porous media, as well as macroscopic and microscopic mechanism of improving heavy oil recovery by chemical additives after steam flooding. The results showed that the fingering phenomenon was generated obviously in the process of steam flooding, which restricted the swept area of steam. Due to decreasing oil-water interface tension, O/W emulsion with lower viscosity was formed to enhance the oil flow capacity and polish up the displacement efficiency of steam after injecting viscosity reducer. And the synergistic effect of viscosity reducer & foaming agent was more conductive to improve displacement efficiency of steam, with 4.3% of oil recovery higher than purely viscosity reducer assisting steam flooding in this process. Microscopic results indicated that thermal foams can be trapped in the porous media to improve injection profile effectively and displace the residual oil caused by steam flooding. The ultimate oil recovery of synergistic development is 65.6%, 11.0% higher than one additive (viscosity reducer). This article can provide reference for the study of thermochemistry assisted steam flooding in heavy oil reservoir.","2D visualized physical model; Microscopic mechanism analysis; Physical simulation; Steam flooding; Synergistic development; Thermochemistry","en","journal article","","","","","","","","2020-01-30","","","Reservoir Engineering","","",""
"uuid:97296e7b-a88d-41f6-92fa-b9c28928a0c1","http://resolver.tudelft.nl/uuid:97296e7b-a88d-41f6-92fa-b9c28928a0c1","Climate-driven seasonal geocenter motion during the GRACE period","Zhang, Hongyue (Chinese Academy of Sciences); Sun, Y. (TU Delft Physical and Space Geodesy; Fuzhou University)","","2018","Annual cycles in the geocenter motion time series are primarily driven by mass changes in the Earth’s hydrologic system, which includes land hydrology, atmosphere, and oceans. Seasonal variations of the geocenter motion have been reliably determined according to Sun et al. (J Geophys Res Solid Earth 121(11):8352–8370, 2016) by combining the Gravity Recovery And Climate Experiment (GRACE) data with an ocean model output. In this study, we reconstructed the observed seasonal geocenter motion with geophysical model predictions of mass variations in the polar ice sheets, continental glaciers, terrestrial water storage (TWS), and atmosphere and dynamic ocean (AO). The reconstructed geocenter motion time series is shown to be in close agreement with the solution based on GRACE data supporting with an ocean bottom pressure model. Over 85% of the observed geocenter motion time series, variance can be explained by the reconstructed solution, which allows a further investigation of the driving mechanisms. We then demonstrated that AO component accounts for 54, 62, and 25% of the observed geocenter motion variances in the X, Y, and Z directions, respectively. The TWS component alone explains 42, 32, and 39% of the observed variances. The net mass changes over oceans together with self-attraction and loading effects also contribute significantly (about 30%) to the seasonal geocenter motion in the X and Z directions. Other contributing sources, on the other hand, have marginal (less than 10%) impact on the seasonal variations but introduce a linear trend in the time series.","Degree 1 coefficients; Geocenter motion; GRACE; Mass transportation","en","journal article","","","","","","","","","","","Physical and Space Geodesy","","",""
"uuid:edf396c5-5c3a-4b5c-9fc4-b8bb5ff6eeee","http://resolver.tudelft.nl/uuid:edf396c5-5c3a-4b5c-9fc4-b8bb5ff6eeee","Qualitative and Quantitative Imaging in Electromagnetic Inverse Scattering Theory","Sun, S. (TU Delft Microwave Sensing, Signals & Systems)","Yarovoy, Alexander (promotor); Kooij, B.J. (promotor); Delft University of Technology (degree granting institution)","2018","The inverse scattering problem is inherently nonlinear and improperly posed. Relevant study, such as the existence and uniqueness of the solution, the completeness of the far field pattern, etc., involves an abstruse mathematical theory. In our daily life, the inversion techniques play a significant role in areas such as radar, sonar, geophysical exploration, medical imaging and nondestructive testing. This thesis is focused on the qualitative and quantitative reconstruction of shape and medium parameters of scattering objects in electromagnetic inverse scattering theory. The major contributions of this thesis are 1) the proposal of a novel cross-correlated error termand 2) the proposal of the sum-of-normregularized reconstruction algorithm. The significance of the former lies in the fact that the proposed error term fills up a gap hidden in the classical “state error Å data error” cost functional. In the optimization approaches, the data error term tends to recover the unknown properties of the objects directly from the measurement data, while the state error term attempts to ensure that the recovered results satisfy Maxwell’s equations in the field domain. In other words, the solution must behave well in both the measurement domain and the field domain. However, there is still a gap in between because the minor mismatch in the field domain is not monitored in the measurement domain. The proposed crosscorrelated error is a constraint which tends to get the mismatch in the field domain under control in the measurement domain. Therefore, one can say that this novel error term revolutionizes the formulation of the minimization functional of inversion techniques based on optimization theory. The significance of the latter is that the proposed reconstruction scheme enables us to excavate the joint information hidden in the formulation of multiple inverse source problems, without any significant additional computational effort. Although the sum-of-norm regularization is not necessarily the best regularization constraint for some complicated scatterers, it demonstrates at least two points: 1) for an inverse source problem, benefits can be obtained from use of different incident fields; 2) the sum-of-norm regularization brings better resolving ability due to the joint processing of the multiple contrast source vectors. The research results in this thesis are also applicable to the acoustic inverse scattering problems. Application of the qualitative and quantitative reconstruction approaches developed in this thesis to the experimental data in different areas of wave-field inversion would be very interesting as future work.","","en","doctoral thesis","","978-94-028-0912-1","","","","Shilong Sun was born in Zhangqiu, Shandong, China, in 1988. He received the B.S. and M.S. degrees in information and communication engineering from the National University of Defense Technology, Changsha, China, in 2011 and 2013, respectively. He joined the Microwave Sensing, Signals and Systems group, Delft University of Technology (The Netherlands) in 2013, where he started working towards his Ph.D. degree in the field of electromagnetic inverse scattering problems.","","","","","Microwave Sensing, Signals & Systems","","",""
"uuid:a36435d7-35a0-4587-b142-a7e2f44ba606","http://resolver.tudelft.nl/uuid:a36435d7-35a0-4587-b142-a7e2f44ba606","High-Speed Flight of Quadrotor Despite Loss of Single Rotor","Sun, Sihao (Student TU Delft); Sijbers, Leon (Student TU Delft); Wang, Xuerui (TU Delft Control & Simulation); de Visser, C.C. (TU Delft Control & Simulation)","","2018","In order to achieve high-speed flight of a damaged quadrotor with complete loss of a single rotor, a multiloop hybrid nonlinear controller is designed. By fully making use of sensor measurements, the model dependence of this control method is reduced, which is conducive to handling disturbance from the unknown aerodynamic effects. This controller is tested on a quadrotor vehicle with one rotor completely removed in the high-speed condition. Free flights are performed in the Open Jet Facility, a large-scale wind tunnel. Over 9 m/s flight speed is reached for the damaged quadrotor in these tests. In addition, several high-speed spin-induced aerodynamic effects are discovered and analyzed.","","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.","","2022-01-05","","","Control & Simulation","","",""
"uuid:2b1865bc-dc6e-4c05-a971-051ad746922c","http://resolver.tudelft.nl/uuid:2b1865bc-dc6e-4c05-a971-051ad746922c","复杂关系网络下,城市发展如何满足利益相关者诉求?: 《城市中国》海外观察员第五期工作坊纪实","Yan, J. (TU Delft Housing Institutions & Governance); Sun, Wenwen (TU Delft Theory, Territories & Transitions); Cannatella, D. (TU Delft Landscape Architecture)","","2018","With the wave of globalization, many countries have witnessed the same trend within which the traditional government-cantered urban management mode is changing. The participation of various non-governmental organizations, private institutions and citizens has made the network of urban governance more complicated than before. In the meanwhile, various departments, organizations and groups show their different demands and interests. How to meet the needs of various participants and deal with this complexity has become an important challenge in urban development. This workshop hopes to understand this trend through the discussion of important aspects of urban development(i.e. the transformation of old cities, social welfare distribution and planning and design projects).Future directions for urban management and development are also discussed.","","zh","journal article","","","","","","","","","","","Housing Institutions & Governance","","",""
"uuid:7a535af4-4b83-4646-9b58-31ece8da76e7","http://resolver.tudelft.nl/uuid:7a535af4-4b83-4646-9b58-31ece8da76e7","A Linear Method for Shape Reconstruction based on the Generalized Multiple Measurement Vectors Model","Sun, S. (TU Delft Microwave Sensing, Signals & Systems); Kooij, B.J. (TU Delft Microwave Sensing, Signals & Systems); Yarovoy, Alexander (TU Delft Microwave Sensing, Signals & Systems); Jin, T. (National University of Defense Technology)","","2018","In this paper, a novel linear method for shape reconstruction is proposed based on the generalized multiple measurement vectors (GMMV) model. Finite difference frequency domain (FDFD) is applied to discretized Maxwell’s equations, and the contrast sources are solved iteratively by exploiting the joint sparsity as a regularized constraint. Cross validation (CV) technique is used to terminate the iterations, such that the required estimation of the noise level is circumvented. The validity is demonstrated with an excitation of transverse magnetic (TM) experimental data, and it is observed that, in the aspect of focusing performance, the GMMV-based linear method outperforms the extensively used linear sampling method (LSM).","?nite difference frequency domain (FDFD); Cross validation (CV); generalized multiple measurement vectors (GMMV); joint sparsity; linear sampling method (LSM); transverse magnetic (TM)","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.","","2021-06-16","","","Microwave Sensing, Signals & Systems","","",""
"uuid:7005d49f-4c41-442c-bf93-4541cec18dcb","http://resolver.tudelft.nl/uuid:7005d49f-4c41-442c-bf93-4541cec18dcb","A recognition model of driving risk based on Belief Rule-Base methodology","Sun, Chuan (Huanggang Normal University); Wu, Chaozhong (Wuhan University of Technology); Chu, Duanfeng (Wuhan University of Technology); Lu, Z. (TU Delft Intelligent Vehicles); Tan, Jian (Huanggang Normal University); Wang, Jianyu (Huanggang Normal University)","","2018","This paper aims to recognize driving risks in individual vehicles online based on a data-driven methodology. Existing advanced driver assistance systems (ADAS) have difficulties in effectively processing multi-source heterogeneous driving data. Furthermore, parameters adopted for evaluating the driving risk are limited in these systems. The approach of data-driven modeling is investigated in this study for utilizing the accumulation of on-road driving data. A recognition model of driving risk based on belief rule-base (BRB) methodology is built, predicting driving safety as a function of driver characteristics, vehicle state and road environment conditions. The BRB model was calibrated and validated using on-road data from 30 drivers. The test results show that the recognition accuracy of our proposed model can reach about 90% in all situations with three levels (none, medium, large) of driving risks. Furthermore, the proposed simplified model, which provides real-time operation, is implemented in a vehicle driving simulator as a reference for future ADAS and belongs to research on artificial intelligence (AI) in the automotive field.","ADAS; belief rule-base; data-driven; Driving data; vehicle driving risk","en","journal article","","","","","","","","","","","Intelligent Vehicles","","",""
"uuid:fbae5c23-b48c-4b00-8e71-b21807c87dbf","http://resolver.tudelft.nl/uuid:fbae5c23-b48c-4b00-8e71-b21807c87dbf","A new hermetic sealing method for ceramic package using nanosilver sintering technology","Zhang, H. (TU Delft Electronic Components, Technology and Materials; Changzhou Institute of Technology Research for Solid State Lighting); Liu, Yang (Harbin University of Science and Technology); Wang, Lingen (Boschman Technologies); Fan, Jiajie (Hohai University; Beijing Research Center; Changzhou Institute of Technology Research for Solid State Lighting); Fan, Xuejun (Lamar University; Changzhou Institute of Technology Research for Solid State Lighting); Sun, Fenglian (Harbin University of Science and Technology); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials; Changzhou Institute of Technology Research for Solid State Lighting)","","2018","High reliable packaging materials are needed for electronics when they work at harsh environments. Among which, the nanosilver material has been widely studied and applied in power electronics due to its low processing temperature and high reliability. This paper investigates the bonding properties of nanosilver sintered hermetic cavity. There are two kinds of lids used in this study, including copper lid and silicon lid. The X-ray and C-Mode Scanning Acoustic Microscopy (C-SAM) results revealed that delamination tended to happen in Cu lid sintered cavity as the recovery of deformed Cu lid was hindered by sintered dense Ag layer. However, no delamination or cracks were found in Si lid sintered cavity. Finite element analysis (FEA) method was used to investigate the effects of lid materials on the stress distribution of lid. The results indicated that the Cu lid sintered cavity showed a much higher stress than the Si lid sintered cavity under the sintering parameters of 250 °C and 10 MPa. There is no obvious change in the stress distribution areas on Cu lid with the increasing of pressures from 5 to 30 MPa. However, the distribution area of stress on Si lid expanded obviously only when the sintering pressure increased to 30 MPa. With the increase of sintering pressures from 5 to 30 MPa, the maximum stresses on Cu lid are almost the same, while increasing trend was found on Si lid.","Harsh environments; Nanosilver; Sintered; Lid; Stress","en","journal article","","","","","","Accepted author manuscript","","2020-01-04","","","Electronic Components, Technology and Materials","","",""
"uuid:9b8a77b0-ed9a-4254-9347-33f123fd66c4","http://resolver.tudelft.nl/uuid:9b8a77b0-ed9a-4254-9347-33f123fd66c4","Effect of Sintering Pressure on the Porosity and the Shear Strength of the Pressure-Assisted Silver Sintering Bonding","Liu, Yang (Harbin University of Science and Technology); Zhang, H. (Harbin University of Science and Technology); Wang, Lingen (Boschman Technologies); Fan, Xuejun (Lamar University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Sun, Fenglian (Harbin University of Science and Technology)","","2018","The microstructure, thickness, porosity, and shear performance of the silver (Ag) sintering layers under different sintering pressures were investigated. Experimental results demonstrated that the thickness and the porosity of the sintering layer decreased when the sintering pressure varied from 5 MPa to 30 MPa. This densification phenomenon facilitated the enhancement of the Ag sintering layers. The shear strength was improved significantly from 44.19 MPa to 69.41 MPa when the sintering pressure increased from 5 MPa to 10 MPa. When the sintering pressure ranged from 10 MPa to 30 MPa, the shear strength presented a slow increase from 69.41 MPa to 73.38 MPa. According to the results of the failure analysis, fracture mode transformation was considered as the basic reason for this phenomenon. The increasing sintering pressure promoted the bonding of the nano-Ag particles during the sintering process. Consequently, the fracture of the sintered-Ag layer transformed from brittle fracture to ductile fracture because of the increasing sintering pressure. The delamination area between Cu and Ni layers coated on the bottom Mo plate was clearly enlarged with the increasing sintering pressure. The delamination between Cu and Ni layers coated on the bottom Mo plate turned to be the main failure mode when the sintering pressure was higher than 10 MPa.","Reliability; sintering; porosity; strength; bonding","en","journal article","","","","","","Accepted author manuscript","","","","","Electronic Components, Technology and Materials","","",""
"uuid:9848d77d-a98a-45c5-8077-aa3735d53f04","http://resolver.tudelft.nl/uuid:9848d77d-a98a-45c5-8077-aa3735d53f04","Production and immobilization of lipase PCL and its application in synthesis of α‐linolenic acid‐rich diacylglycerol","Liu, Nan (South China University of Technology); Liu, D. (South China University of Technology); Wang, Weifei (Guangdong Academy of Agricultural Sciences); Hollmann, F. (TU Delft BT/Biocatalysis); Xu, Long (South China University of Technology); Ma, Yunjian (South China University of Technology); Yang, Bo (South China University of Technology); Bai, Weidong (Zhongkai University of Agriculture and Engineering); Sun, Xiaotao (Beijing Technology and Business University); Wang, Yonghua (South China University of Technology)","","2018","α‐Linolenic acid‐rich diacylglycerol has been demonstrated with promising health promotion functions. This study examined the production, immobilization of lipase PCL, and its application in the synthesis of diacylglycerol by esterification of α‐linolenic acid with glycerol. The resin ECR8806 was selected as an effective support for the immobilization of lipase PCL. Fourier transform infrared and Laser scanning confocal microscope analysis proved that the lipase was successfully immobilized on the resin. Compared with the free PCL, the immobilized one exhibited higher temperature tolerance. Under optimized reaction conditions, a DAG content of 54.49% were obtained. After further purified by molecular distillation, the purity of DAG was up to 99.28%. During esterification, the immobilized PCL was quite stable and retained more than 91.60% of its initial activity after 10 cycles. These new findings on the immobilized PCL will make it to be a prospective enzyme in oils and fats industry.","diacylglycerol; esterification; immobilization; reusability; a-Linolenic acid","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-01-23","","","BT/Biocatalysis","","",""
"uuid:e303d23c-9a89-4d58-8dc3-1115e7efc030","http://resolver.tudelft.nl/uuid:e303d23c-9a89-4d58-8dc3-1115e7efc030","Thermal Management on IGBT Power Electronic Devices and Modules","Qian, C. (Beihang University); Mirza Gheytaghi, Amir (TU Delft Electronic Components, Technology and Materials); Fan, J. (Hohai University; Changzhou Institute of Technology Research for Solid State Lighting); Tang, H. (TU Delft Electronic Components, Technology and Materials; Changzhou Institute of Technology Research for Solid State Lighting); Sun, B. (TU Delft Electronic Components, Technology and Materials; Changzhou Institute of Technology Research for Solid State Lighting); Ye, H. (TU Delft Electronic Components, Technology and Materials; Chongqing University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials; Chinese Academy of Sciences)","","2018","As an increasing attention towards sustainable development of energy and environment, the power electronics (PEs) are gaining more and more attraction on various energy systems. The insulated gate bipolar transistor (IGBT), as one of the PEs with numerous advantages and potentials for development of higher voltage and current ratings, has been used in a board range of applications. However, the continuing miniaturization and rapid increasing power ratings of IGBTs have remarkable high heat flux, which requires complex thermal management. In this paper, studies of the thermal management on IGBTs are generally reviewed including analyzing, comparing, and classifying the results originating from these researches. The thermal models to accurately calculate the dynamic heat dissipation are divided into analytical models, numerical models, and thermal network models, respectively. The thermal resistances of current IGBT modules are also studied. According to the current products on a number of IGBTs, we observe that the junction-to-case thermal resistance generally decreases inversely in terms of the total thermal power. In addition, the cooling solutions of IGBTs are reviewed and the performance of the various solutions are studied and compared. At last, we have proposed a quick and efficient evaluation judgment for the thermal management of the IGBTs depended on the requirements on the junction-to-case thermal resistance and equivalent heat transfer coefficient of the test samples.","Power electronics; IGBT; thermal management; cooling; qualifications; OA-Fund TU Delft","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:1ba59274-d7d0-4ed1-9287-b99888639532","http://resolver.tudelft.nl/uuid:1ba59274-d7d0-4ed1-9287-b99888639532","Improvements in the Monthly Gravity Field Solutions Through Modeling the Colored Noise in the GRACE Data","Guo, Xiang (Wuhan University); Zhao, Qile (Wuhan University); Ditmar, P.G. (TU Delft Physical and Space Geodesy); Sun, Yu (Fuzhou University); Liu, Jingnan (Wuhan University)","","2018","The Gravity Recovery And Climate Experiment (GRACE) mission has achieved a quantum leap in knowledge of the Earth's gravity field. However, current gravity field solutions still cannot reach the prelaunch baseline accuracy. One of the reasons for that is the presence of colored noise in GRACE data, which is typically ignored in the classical dynamic approach to gravity field modeling. In this research, we propose to account for colored noise in the classical dynamic approach by applying the frequency-dependent data weighting (FDDW) scheme, so that enhanced estimates of gravity field solutions are produced. The monthly solutions are compared with those produced using the standard least squares adjustment without a data weighting scheme. The comparison is performed in both spectral and spatial domains, showing the positive effect of the FDDW scheme in all considered cases. For instance, the cumulative geoid height errors up to degree 96 are reduced by 18%. In the spatial domain, the FDDW scheme lowers noise level in mass changes over the oceans, Mississippi river basin, and Greenland by 20, 38, and 23%, respectively, when compared to the without a data weighting scheme. In addition, the consistency of mass changes over the Mississippi and Congo river basins with those inferred from the state-of-the-art hydrology model WaterGAP is substantially improved when the FDDW scheme is applied. These results indicate that modeling colored noise in the GRACE data allows to significantly improve the recovered monthly solutions. This finding is likely applicable also to the GRACE Follow-On mission.","","en","journal article","","","","","","","","","","","Physical and Space Geodesy","","",""
"uuid:3498cc8d-b6f4-48e4-8643-b588aca477fa","http://resolver.tudelft.nl/uuid:3498cc8d-b6f4-48e4-8643-b588aca477fa","Weather field reconstruction using aircraft surveillance data and a novel meteo-particle model","Sun, Junzi (TU Delft Control & Simulation); Vû, Huy (Student TU Delft); Ellerbroek, Joost (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2018","Wind and temperature data are important parameters in aircraft performance studies. The lack of accurate measurements of these parameters forces researchers to rely on numerical weather prediction models, which are often filtered for a larger area with decreased local accuracy. Aircraft, however, also transmit information related to weather conditions, in response to interrogation by air traffic controller surveillance radars. Although not intended for this purpose, aircraft surveillance data contains information that can be used for weather models. This paper presents a method that can be used to reconstruct a weather field from surveillance data that can be received with a simple 1090 MHz receiver. Throughout the paper, we answer two main research questions: how to accurately infer wind and temperature from aircraft surveillance data, and how to reconstruct a real-time weather grid efficiently. We consider aircraft as moving sensors that measure wind and temperature conditions indirectly at different locations and flight levels. To address the first question, aircraft barometric altitude, ground velocity, and airspeed are decoded from down-linked surveillance data. Then, temperature and wind observations are computed based on aeronautical speed conversion equations. To address the second question, we propose a novel Meteo-Particle (MP) model for constructing the wind and temperature fields. Short-term local prediction is also possible by employing a predictor layer. Using an unseen observation test dataset, we are able to validate that the mean absolute errors of inferred wind and temperature
using MP model are 67% and 26% less than using the interpolated model based
on GFS reanalysis data.","","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:6c3c1656-b2f2-419b-984a-339975784f0c","http://resolver.tudelft.nl/uuid:6c3c1656-b2f2-419b-984a-339975784f0c","A Linear Model for Microwave Imaging of Highly Conductive Scatterers","Sun, S. (TU Delft Microwave Sensing, Signals & Systems); Kooij, B.J. (TU Delft Microwave Sensing, Signals & Systems); Yarovoy, Alexander (TU Delft Microwave Sensing, Signals & Systems)","","2018","In this paper, a linear model based on multiple measurement vectors' model is proposed to formulate the inverse scattering problem of highly conductive objects at one single frequency. Considering the induced currents that are mostly distributed on the boundaries of the scatterers, joint sparse structure is enforced by a sum-of-norm regularization. Since no a priori information is required and no approximation of the scattering model has been made, the proposed method is versatile. Imaging results with transverse magnetic and transverse electric polarized synthetic data and Fresnel data demonstrate its higher resolving ability than both linear sampling method and its improved version with higher, but acceptable, computational complexity.","Inverse scattering problem; joint sparse structure; multiple measurement vectors (MMVs); sum-of-norm regularization constraint; transverse electric (TE); transverse magnetic (TM)","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.","","","","","Microwave Sensing, Signals & Systems","","",""
"uuid:04f66db9-3d93-401c-b779-f4b8163185fd","http://resolver.tudelft.nl/uuid:04f66db9-3d93-401c-b779-f4b8163185fd","Extension of the GMMV-based Linear Method to Quantitative Inverse Scattering","Sun, S. (TU Delft Microwave Sensing, Signals & Systems); Kooij, B.J. (TU Delft Microwave Sensing, Signals & Systems); Yarovoy, Alexander (TU Delft Microwave Sensing, Signals & Systems)","","2018","The linear shape reconstruction method based on the generalized multiple measurement vectors model is a newly proposed approach which is able to effectively retrieve the morphological information of dielectric/metallic scatterers with competitive imaging resolution. In this letter, we have extended this approach to quantitative inversion, and the proposed approach turns out to be effective even for complicated scatterers and highly efficient in comparison to nonlinear iterative methods. The inverted results obtained by processing the transverse magnetic polarized Fresnel data-sets of the year 2005 demonstrate the validity of the proposed method in real applications.","Generalized multiple measurement vectors (GMMV); linear shape reconstruction method; quantitative inverse scattering; transverse magnetic (TM)","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.","","","","","Microwave Sensing, Signals & Systems","","",""
"uuid:7950fa2e-2144-4287-9f43-7146e1675c60","http://resolver.tudelft.nl/uuid:7950fa2e-2144-4287-9f43-7146e1675c60","An environmentally friendly electro-oxidative approach to recover valuable elements from NdFeB magnet waste","Venkatesan, P. (TU Delft (OLD) MSE-3); Sun, Z.H.I. (Chinese Academy of Sciences); Sietsma, J. (TU Delft (OLD) MSE-3); Yang, Y. (TU Delft (OLD) MSE-3)","","2018","In this manuscript, we demonstrate a room temperature electrochemical process for efficiently recycling NdFeB magnet waste. First, the magnet waste was completely leached with HCl and then, in-situ electrochemical oxidation was performed to selectively oxidize Fe(II) in the leachate to Fe(III). Finally, oxalic acid was added directly to the electro-oxidized leachate which selectively precipitated more than 98% of rare earth elements as rare-earth oxalates. The calcination of rare-earth oxalates produced mixed rare-earth oxides of 99.2% purity and a marketable Fe(III) solution as by-product. The electro-oxidized leachate was also subjected to an alternative neutralization route in which ammonium hydroxide was added to remove iron as ferric hydroxide. The iron free leachate with rare earth elements and cobalt was then subjected to oxalic acid precipitation treatment, which finally produced rare-earth oxides of 99.7% purity. Furthermore, a cobalt-rich solution was obtained in the end and electrowinning studies performed on the solution showed the feasibility of recovering pure metallic cobalt.","","en","journal article","","","","","","Accepted Author Manuscript","","2019-10-05","","","(OLD) MSE-3","","",""
"uuid:611693b2-046a-4cbc-a61b-d1793e52f523","http://resolver.tudelft.nl/uuid:611693b2-046a-4cbc-a61b-d1793e52f523","Aircraft initial mass estimation using Bayesian inference method","Sun, Junzi (TU Delft Control & Simulation); Ellerbroek, Joost (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2018","Aircraft mass is a crucial piece of information for studies on aircraft performance, trajectory prediction, and many other topics of aircraft traffic management. However, It is a common challenge for researchers, as well as air traffic control, to access this proprietary information. Previously, several studies have proposed methods to estimate aircraft weight based on specific parts of the flight. Due to inaccurate input data or biased assumptions, this often leads to less confident or inaccurate estimations. In this paper, combined with a fuel-flow model, different aircraft initial masses are computed independently using the total energy model and reference model at first. It then adopts a Bayesian approach that uses a prior probability of aircraft mass based on empirical knowledge and computed aircraft initial masses to produce the maximum a posteriori estimation. Variation in results caused by dependent factors such as prior, thrust and wind are also studied. The method is validated using 50 test flights of a Cessna Citation II aircraft, for which measurements of the true mass were available. The validation results show a mean absolute error of 4.3% of the actual aircraft mass.","Aircraft mass; Weight estimation; Bayesian inference","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.","","2018-09-10","","","Control & Simulation","","",""
"uuid:9977a616-4506-4acb-9d27-b9e27f9ddb8d","http://resolver.tudelft.nl/uuid:9977a616-4506-4acb-9d27-b9e27f9ddb8d","Aircraft Drag Polar Estimation Based on a Stochastic Hierarchical Model","Sun, Junzi (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation); Ellerbroek, Joost (TU Delft Control & Simulation)","","2018","The aerodynamic properties of an aircraft determine a crucial part of the aircraft performance model. Deriving accurate aerodynamic coefficients requires detailed knowledge of the aircraft’s design. These designs and parameters are well protected by aircraft manufacturers. They rarely can be used in public research. Very detailed aerodynamic models are often not necessary in air traffic management related research, as they often use a simplified point-mass aircraft performance model. In these studies, a simple quadratic relation often assumed to compute the drag of an aircraft based on the required lift. This so-called drag polar describes an approximation of the drag coefficient based on the total lift coefficient. The two key parameters in the drag polar are the zero-lift drag coefficient and the factor to calculate the lift-induced part of the drag coefficient. Thanks to this simplification of the flight model together with accurate flight data, we are able to estimate these aerodynamic parameters based on flight data. In this paper, we estimate the drag polar based on a novel stochastic total energy model using Bayesian computing and Markov chain Monte Carlo sampling. The method is based on the stochastic hierarchical modeling approach. With sufficiently accurate flight data and some basic knowledge of aircraft and their engines, the drag polar can be estimated. We also analyze the results and compare them to the commonly used Base of Aircraft Data model. The mean absolute difference among 20 common aircraft for zero-lift drag coefficient and lift-induced drag factor are 0.005 and 0.003 respectively. At the end of this paper, the drag polar models in different flight phases for these common commercial aircraft types are shared.","aircraft performance; drag polar; aerodynamic coefficient; Bayesian computing; MCMC","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.","","2019-07-01","","","Control & Simulation","","",""
"uuid:2b02d90b-9c33-49af-82bb-d32fd4061919","http://resolver.tudelft.nl/uuid:2b02d90b-9c33-49af-82bb-d32fd4061919","Aircraft Mass and Thrust Estimation Using Recursive Bayesian Method","Sun, Junzi (TU Delft Control & Simulation); Blom, H.A.P. (TU Delft Air Transport & Operations; Royal Netherlands Aerospace Centre NLR); Ellerbroek, Joost (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2018","This paper focuses on estimating aircraft mass and thrust setting using a recursive Bayesian method called particle filtering. The method is based on a nonlinear state-space system derived from aircraft point-mass performance models. Using solely ADS-B and Mode-S data, flight states such as position, velocity, and wind speed are collected and used for the estimation. An important aspect of particle filtering is noise modeling. Four noise models are proposed in this paper based on the native ADS-B Navigation Accuracy Category (NAC) parameters. Simulations, experiments, and validation, based on a number of flights are carried out to test the theory. As a result, convergence of the estimation can usually be obtained within 30 seconds for any climbing flight. The method proposed in this paper not only provides final estimates, but also defines the limits of noise above which estimation of mass and thrust becomes impossible. When validated with a dataset consisting of the measured true mass and thrust of 50 Cessna Citation II flights, the stochastic recursive Bayesian approach proposed in this paper yields a mean absolute error of 4.6%.","aircraft; state estimation; point-mass model; measurement noise; particle filter; Bayesian estimation","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.","","2021-12-08","","","Control & Simulation","","",""
"uuid:85499897-c951-471c-bd74-c1d82b4036e1","http://resolver.tudelft.nl/uuid:85499897-c951-471c-bd74-c1d82b4036e1","A benchmark study of numerical implementations of the sea level equation in GIA modelling","Martinec, Z. (Charles University; Dublin Institute for Advanced Studies); Klemann, V. (Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences); van der Wal, W. (TU Delft Astrodynamics & Space Missions); Riva, R.E.M. (TU Delft Physical and Space Geodesy); Spada, G. (Università di Urbino Carlo Bo, Urbino); Sun, Y. (TU Delft Physical and Space Geodesy); Melini, D. (National Institute of Geophysics and Volcanology); Kachuck, S. B. (Cornell University); Barletta, V. (Technical University of Denmark); Simon, K.M. (TU Delft Physical and Space Geodesy)","","2018","The ocean load in glacial isostatic adjustment (GIA) modelling is represented by the so-called sea level equation (SLE). The SLE describes the mass redistribution of water between ice sheets and oceans on a deforming Earth. Despite various teams independently investigating GIA, there has been no systematic intercomparison among the numerical solvers of the SLE through which the methods may be validated. The goal of this paper is to present a series of synthetic examples designed for testing and comparing the numerical implementations of the SLE in GIA modelling. The 10 numerical codes tested combine various temporal and spatial parametrizations. The time-domain or Laplace-domain discretizations are used to solve the SLE through time, while spherical harmonics, finite differences or finite elements parametrize the GIA-related field variables spatially. The surface ice-water load and solid Earth's topography are represented spatially either on an equiangular grid, a Gauss-Legendre or an equiarea grid with icosahedron-shaped spherical pixels. Comparisons aremade in a series of five benchmark examples with an increasing degree of complexity. Due to the complexity of the SLE, there is no analytical solution to it. The accuracy of the numerical implementations is therefore assessed by the differences of the individual solutions with respect to a reference solution. While the benchmark study does not result in GIA predictions for a realistic loading scenario, we establish a set of agreed-upon results that can be extended in the future by including more complex case studies, such as solutions with realistic loading scenarios, the rotational feedback in the linear-momentum equation, and by considering a 3-D viscosity structure of the Earth's mantle. The test computations performed so far show very good agreement between the individual results and their ability to capture the main features of sea-surface variation and the surface vertical displacement. The differences found can often be attributed to the different approximations inherent in the various algorithms. This shows the accuracy that can be expected from different implementations of the SLE, which helps to assess differences noted in the literature between predictions for realistic loading cases.","And modelling; Dynamics of lithosphere and mantle; Dynamics: gravity and tectonics; Mechanics; Numerical solutions; Rheology: mantle; Sea level change; Theory","en","journal article","","","","","","","","","","","Astrodynamics & Space Missions","","",""
"uuid:9a3559e9-27b6-47cd-820d-d7ecc76cbc06","http://resolver.tudelft.nl/uuid:9a3559e9-27b6-47cd-820d-d7ecc76cbc06","Recurrent knowledge graph embedding for effective recommendation","Sun, Zhu (Nanyang Technological University); Yang, J. (University of Fribourg); Zhang, J. (Nanyang Technological University); Bozzon, A. (TU Delft Web Information Systems); Huang, Long Kai (Nanyang Technological University); Xu, Chi (Singapore Institute of Manufacturing Technology)","","2018","Knowledge graphs (KGs) have proven to be effective to improve recommendation. Existing methods mainly rely on hand-engineered features from KGs (e.g., meta paths), which requires domain knowledge. This paper presents RKGE, a KG embedding approach that automatically learns semantic representations of both entities and paths between entities for characterizing user preferences towards items. Specifically, RKGE employs a novel recurrent network architecture that contains a batch of recurrent networks to model the semantics of paths linking a same entity pair, which are seamlessly fused into recommendation. It further employs a pooling operator to discriminate the saliency of different paths in characterizing user preferences towards items. Extensive validation on real-world datasets shows the superiority of RKGE against state-of-the-art methods. Furthermore, we show that RKGE provides meaningful explanations for recommendation results.","Attention Mechanism; Knowledge Graph; Recurrent Neural Network; Semantic Representation","en","conference paper","Association for Computer Machinery","","","","","Accepted author manuscript","","","","","Web Information Systems","","",""
"uuid:46ef3f74-0cf8-4637-a215-f09084439cef","http://resolver.tudelft.nl/uuid:46ef3f74-0cf8-4637-a215-f09084439cef","Combined Effects of Unsteady River Discharges and Wave Conditions on River Mouth Bar Morphodynamics","Gao, Weilun (Beijing Normal University); Shao, Dongdong (Beijing Normal University); Wang, Zhengbing (TU Delft Coastal Engineering; Beijing Normal University; Deltares); Nardin, William (University of Maryland); Yang, Wei (Beijing Normal University); Sun, Tao (Beijing Normal University); Cui, Baoshan (Beijing Normal University)","","2018","River mouth bar formation, a key process in fluvial-deltaic morphodynamics, is subject to both river discharge and waves. Given the increasing variability of both forcings under continuous climate change and human interventions, assessing their combined effects on mouth bar formatio n is an imperative issue. In this study, an extensive set of combined high and low river flows coupled with varying wave conditions and sediment grain sizes was assumed for numerical experiments conducted in Delft3D-SWAN. The results suggested that three regimes existed for mouth bar formation, namely, stable, ephemeral, and absent. These regimes corresponded to consistently weak, initially-weak-then-strong, and initially strong relative wave strengths, respectively, during the onset and reworking stages. Suppression of mouth bar formation further led to the inhibition of deltaic distributary networks. These findings have important implications for water and sediment management strategies, such as water diversion and dam regulation, in estuaries and deltas to prevent coastal erosion.","","en","journal article","","","","","","","","2019-07-01","","","Coastal Engineering","","",""
"uuid:0280356b-dba3-4912-8bda-46c8f98197fa","http://resolver.tudelft.nl/uuid:0280356b-dba3-4912-8bda-46c8f98197fa","Geocentre motion and Earth's dynamic oblateness time-series derived from GRACE CSR RL06 solutions and geophysical models","Sun, Y. (TU Delft Physical and Space Geodesy; Fuzhou University); Riva, R.E.M. (TU Delft Physical and Space Geodesy); Ditmar, P.G. (TU Delft Physical and Space Geodesy); Klees, R. (TU Delft Physical and Space Geodesy)","","2018","With the launch of the Gravity Recovery and Climate Experiment (GRACE) satellite mission in 2002 (http://www.csr.utexas.edu/grace), Satellite Gravimetry has become a unique tool to estimate hydrological water balance and mass balance of ice sheets, as well as to monitor mass re-distribution in the oceans and the solid Earth. However, satellite gravimetry still suffers from a poor estimation of temporal variations in the spherical harmonic coefficient C20 (which is associated with the Earth's dynamic oblateness). Therefore, these variations are typically extracted from Satellite Laser Ranging (SLR) data. Furthermore, satellite gravimetry is not sensitive to variations of degree-1 spherical harmonic coefficients (i.e., C10, C11, and S11), which are associated with the geocentre motion. Swenson et al (2008) proposed to restore those coefficients using as a reference an area where the mass anomalies are known. Such an area was chosen as the entire world ocean; mass anomalies there were defined as variations of the Ocean Bottom Pressure based on an ocean circulation model. The Glacial Isostatic Adjustment signal was corrected for by applying a remove-restore approach.
Sun et al (2016) further developed the technique by Swenson et al (2008). First, the Self-Attraction and Loading (SAL) effects were additionally modelled in order to estimate water re-distribution in the ocean more accurately. Second, a buffer zone around the continents was excluded from the reference area in order to suppress the effect of “signal leakage” caused by a limited spatial resolution of satellite gravimetry. It was shown that the modified technique allows for an accurate estimation of both degree-1 and C20 variations.","","en","poster","","","","","","","","","","","Physical and Space Geodesy","","",""
"uuid:a25085ae-f3dc-495f-bfa8-04d81b9140a3","http://resolver.tudelft.nl/uuid:a25085ae-f3dc-495f-bfa8-04d81b9140a3","Assessment of GRACE monthly solutions by quantifying the noise level in mass anomaly time-series with the variance component estimation (PPT)","Ditmar, P.G. (TU Delft Physical and Space Geodesy); Brussee, M. (Student TU Delft); Sun, Y. (TU Delft Physical and Space Geodesy; Fuzhou University); Riva, R.E.M. (TU Delft Physical and Space Geodesy)","","2018","","","en","other","","","","","","","","","","","Physical and Space Geodesy","","",""
"uuid:e941d5e3-f213-42f6-b997-18a824518e57","http://resolver.tudelft.nl/uuid:e941d5e3-f213-42f6-b997-18a824518e57","A probabilistic physics-of-failure reliability assessment approach for integrated LED lamps","Sun, B. (Guangdong University of Technology); Fan, J. (Hohai University); Fan, Xuejun (Lamar University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2018","This work studies the effect of randomness of LED's lumen depreciation on reliability of the entire LED lamp. An integrated LED light bulb is selected as carrier of the proposed method. A PoF based lumen depreciation model and electronic-thermal simulations are introduced for reliability prediction. The normal distribution is used to describe the statistical distribution of LEDs. The probabilities of the driver's catastrophic failures and lumen can then be obtained by Monte Carlo simulations by considering the increase of lamp's temperature. The effect of the lumen depreciation to the entire lamp is studied with two scenarios: constant light mode and constant current mode.","Reliability; Junctions; LED lamps; Light sources; Temperature distribution; Integrated circuit modeling","en","conference paper","IEEE","","","","","Accepted author manuscript","","","","","Electronic Components, Technology and Materials","","",""
"uuid:1deee01a-f377-443a-aa7a-d1eea632fe8a","http://resolver.tudelft.nl/uuid:1deee01a-f377-443a-aa7a-d1eea632fe8a","Integrating the Multi-Functional Space and Long-Span Structure for Sports Arena Design: A design exploration process based on design optimization and self-organizing map","Pan, W. (TU Delft Design Informatics; South China University of Technology); Sun, Yimin (South China University of Technology); Turrin, M. (TU Delft Design Informatics); Louter, P.C. (TU Delft OLD Structural Design); Sariyildiz, I.S. (TU Delft Design Informatics)","Mueller, Caitlin (editor); Adriaenssens, Sigrid (editor)","2018","The multi-functional space of sports arena is highly related to the long-span structure. To support the integration of these two aspects, design optimization combining parametric modeling, performance simulations, and searching algorithm can be used. However, optimization is powerful in dealing with quantitative performance, but for some soft requirements on buildings, design exploration of geometries based on the judgments of architects is still necessary. Self-organizing map (SOM), as a model-based clustering algorithm, can be used to support this kind of explorations on geometric typology. Nevertheless, it is difficult to ensure the accuracy of clustering, especially for complex parametric models. To support the design exploration on geometry (besides the exploration on quantitative performance supported by optimization) during the conceptual design of sports arenas, this paper proposed a process based on a versatile and flexible parametric model for sports arenas and self-organizing map (SOM). Within this process, to increase the accuracy of SOM clustering, a pre-processing step for the parameters of design alternatives is also proposed. A design of a hypothetic sports arena is used as a case to demonstrate and verify the process.","design exploration; self-organizing map (SOM); clustering; parametric modeling; multi-objective optimization (MOO); multi-functional space of sports arenas; long-span structure","en","conference paper","IASS","","","","","","","","","","Design Informatics","","",""
"uuid:7f5469ca-91d2-4c3a-b41a-ea86987dbf58","http://resolver.tudelft.nl/uuid:7f5469ca-91d2-4c3a-b41a-ea86987dbf58","Report from the 18th International Planning History Society conference: 15–19 July 2018, Yokohama, Japan","Sun, Y. (Tianjin University); Schwake, G. (TU Delft History, Form & Aesthetics); Zhu, K. (TU Delft History, Form & Aesthetics); Zhu, P. (TU Delft History, Form & Aesthetics)","","2018","","","en","journal article","","","","","","","","","","","History, Form & Aesthetics","","",""
"uuid:49044731-c1e5-4f17-ba32-f13dbfa57b25","http://resolver.tudelft.nl/uuid:49044731-c1e5-4f17-ba32-f13dbfa57b25","Multi-disciplinary and multi-objective optimization problem re-formulation in computational design exploration: A case of conceptual sports building design","Yang, D. (TU Delft Design Informatics; South China University of Technology); Ren, Shibo (Arup Limited, Netherlands); Turrin, M. (TU Delft Design Informatics); Sariyildiz, I.S. (TU Delft Design Informatics); Sun, Y. (South China University of Technology)","","2018","The benefits of applying multi-objective optimization (MOO) in building design have been increasingly recognized in recent decades. The existing or traditional computational design optimization (CDO) approaches mostly focus on optimization problem solving (OPS), as they often conduct optimizations directly by assuming the optimization problems in question are good enough. In contrast, the computational design exploration (CDE) approaches defined in this research mainly focus on optimization problem formulation (OPF), which are considered more essential and aim to achieve or ensure appropriate optimization problems before conducting optimizations. However, the application of the CDE is very limited especially in conceptual architectural design. The necessity of re-formulating original optimization problems and its potential impacts on optimization results are often overlooked or not emphasized enough. This paper proposes a new CDE approach that highlights the knowledge-supported re-formulation of a changeable initial optimization problem. It improves upon the traditional CDO approach by introducing a changeable initial OPF and inserting a CDE module. The changeable initial OPF allows expanding the dimensionality of an objective space and design space being investigated, and the CDE module can re-formulate the changeable optimization problem using the information and knowledge extracted from statistical analyses. To facilitate designers in achieving the proposed approach, an improved computational platform is used which combines parametric modeling software (including simulation plug-ins) and design optimization software. Assisted by the platform, the proposed approach is applied to the conceptual design of an indoor sports building that considers multi-disciplinary performance criteria (including architecture-, climate- and structure-related criteria) and a wide range of geometric variations. Through the case study, this paper demonstrates the use of the proposed approach, verifies its benefits over the traditional method, and unveils the factors that may affect the behaviour of the proposed approach. Besides, it also shows the suitability of the computational platform used.","Architectural performance; Climate performance; Computational design exploration; Knowledge extraction; Multi-disciplinary optimization; Multi-objective optimization; Optimization problem re-formulation; Sports buildings; Statistical analysis techniques; Structural performance","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.","","2018-10-25","","","Design Informatics","","",""
"uuid:30c6cf5a-99d9-4991-a948-769d58ecb040","http://resolver.tudelft.nl/uuid:30c6cf5a-99d9-4991-a948-769d58ecb040","Charge carrier-selective contacts for nanowire solar cells","Oener, Sebastian Z. (University of Oregon; AMOLF); Cavalli, A. (Eindhoven University of Technology); Sun, Hongyu (AMOLF); Haverkort, Jos E.M. (Eindhoven University of Technology); Bakkers, E.P.A.M. (TU Delft QN/Bakkers Lab; Eindhoven University of Technology; Kavli institute of nanoscience Delft); Garnett, Erik C. (AMOLF)","","2018","Charge carrier-selective contacts transform a light-absorbing semiconductor into a photovoltaic device. Current record efficiency solar cells nearly all use advanced heterojunction contacts that simultaneously provide carrier selectivity and contact passivation. One remaining challenge with heterojunction contacts is the tradeoff between better carrier selectivity/contact passivation (thicker layers) and better carrier extraction (thinner layers). Here we demonstrate that the nanowire geometry can remove this tradeoff by utilizing a permanent local gate (molybdenum oxide surface layer) to control the carrier selectivity of an adjacent ohmic metal contact. We show an open-circuit voltage increase for single indium phosphide nanowire solar cells by up to 335 mV, ultimately reaching 835 mV, and a reduction in open-circuit voltage spread from 303 to 105 mV after application of the surface gate. Importantly, reference experiments show that the carriers are not extracted via the molybdenum oxide but the ohmic metal contacts at the wire ends.","","en","journal article","","","","","","","","","","","QN/Bakkers Lab","","",""
"uuid:047c6550-ce95-40aa-863e-c1f58bef1e54","http://resolver.tudelft.nl/uuid:047c6550-ce95-40aa-863e-c1f58bef1e54","Inversion of Multifrequency Data With the Cross-Correlated Contrast Source Inversion Method","Sun, S. (TU Delft Microwave Sensing, Signals & Systems); Kooij, B.J. (TU Delft Microwave Sensing, Signals & Systems); Yarovoy, Alexander (TU Delft Microwave Sensing, Signals & Systems)","","2018","Cross-correlated contrast source inversion (CC-CSI) is a nonlinear iterative inversion method that is proposed recently for solving the inverse scattering problems. In CC-CSI, a cross-correlated error is constructed and introduced to the cost functional, which improves the inversion ability when compared to the classical design of the cost functional by exploiting the mismatch between the data error and state error. In this paper, the multifrequency inversion for electromagnetic waves is considered and a multifrequency version of CC-CSI is proposed. Numerical and experimental inversion results of both transverse magnetic and transverse electric polarization demonstrate that when multifrequency data are available, CC-CSI still outperforms the multiplicative-regularized CSI method in the inversion of more complicated scatterers.","cross-correlated contrast source inversion (CC-CSI); multifrequency inversion; multiplicative-regularized CSI (MR-CSI); nonlinear iterative inversion; Transverse electric (TE); transverse magnetic (TM)","en","journal article","","","","","","green","","","","","Microwave Sensing, Signals & Systems","","",""
"uuid:ab7a5c5a-2d1b-423c-8860-a9b9f08cf270","http://resolver.tudelft.nl/uuid:ab7a5c5a-2d1b-423c-8860-a9b9f08cf270","Mode I fatigue delamination growth with fibre bridging in multidirectional composite laminates","Yao, Liaojun (Harbin Institute of Technology; Northwestern Polytechnical University); Sun, Yi (Harbin Institute of Technology); Guo, Licheng (Harbin Institute of Technology); Lyu, Xiuqi (Purdue University); Zhao, Meiying (Northwestern Polytechnical University); Jia, Liyong (AVIC the First Aircraft Institute); Alderliesten, R.C. (TU Delft Structural Integrity & Composites); Benedictus, R. (TU Delft Structural Integrity & Composites)","","2018","Fatigue delamination in multidirectional composite laminates was experimentally investigated in present study. Both the Paris relation and a modified Paris relation (with a new similitude parameter) were employed to interpret fatigue delamination with significant fibre bridging. The results clearly demonstrated that fatigue delamination was independent of fibre bridging, if a reasonable similitude parameter was used in data reduction. As a result, a master resistance curve can be fitted to determine fatigue crack growth with different amounts of fibre bridging. The energy principles were subsequently used to provide physical interpretation on fatigue delamination. The results indicated the energy release for the same fatigue crack growth remained constant with fibre bridging. Bridging fibres in most cases just periodically stored and released strain energy under fatigue loading, but had little contribution to real energy release. The master resistance curve was finally applied to predict fatigue delamination with fibre bridging. Acceptable agreement between predictions and experiments was achieved, demonstrating the validation of the modified Paris relation in fibre-bridged fatigue delamination study.","Delamination; Fatigue; Fibre bridging; Multidirectional composite laminates","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.","","2021-01-01","","","Structural Integrity & Composites","","",""
"uuid:5a8fa606-444f-4cd8-b364-5db930111a32","http://resolver.tudelft.nl/uuid:5a8fa606-444f-4cd8-b364-5db930111a32","Coupling dynamics of epidemic spreading and information diffusion on complex networks","Zhan, X. (TU Delft Multimedia Computing; Hangzhou Normal University); Liu, Chuang (Hangzhou Normal University); Zhou, Ge (Hangzhou Normal University; Shanghai Jiao Tong University); Zhang, Zi-Ke (Hangzhou Normal University; Shanghai Jiao Tong University); Sun, Gui-Quan (Shanxi University); Zhu, Jonathan J. H. (City University of Hong Kong); Jin, Zhen (Shanxi University)","","2018","The interaction between disease and disease information on complex networks has facilitated an interdisciplinary research area. When a disease begins to spread in the population, the corresponding information would also be transmitted among individuals, which in turn influence the spreading pattern of the disease. In this paper, firstly, we analyze the propagation of two representative diseases (H7N9 and Dengue fever) in the real-world population and their corresponding information on Internet, suggesting the high correlation of the two-type dynamical processes. Secondly, inspired by empirical analyses, we propose a nonlinear model to further interpret the coupling effect based on the SIS (Susceptible-Infected-Susceptible) model. Both simulation results and theoretical analysis show that a high prevalence of epidemic will lead to a slow information decay, consequently resulting in a high infected level, which shall in turn prevent the epidemic spreading. Finally, further theoretical analysis demonstrates that a multi-outbreak phenomenon emerges via the effect of coupling dynamics, which finds good agreement with empirical results. This work may shed light on the in-depth understanding of the interplay between the dynamics of epidemic spreading and information diffusion.","Coupling dynamics; Epidemic spreading; Information diffusion","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.","","","","","Multimedia Computing","","",""
"uuid:467a0784-3d30-4f4c-939e-4e324c29f918","http://resolver.tudelft.nl/uuid:467a0784-3d30-4f4c-939e-4e324c29f918","Epidemic dynamics on information-driven adaptive networks","Zhan, X. (TU Delft Multimedia Computing; Hangzhou Normal University); Liu, Chuang (Hangzhou Normal University); Sun, Gui-Quan (Shanxi University); Zhang, Zi-Ke (Hangzhou Normal University; Shanghai Jiao Tong University; Alibaba Research Institute)","","2018","Research on the interplay between the dynamics on the network and the dynamics of the network has attracted much attention in recent years. In this work, we propose an information-driven adaptive model, where disease and disease information can evolve simultaneously. For the information-driven adaptive process, susceptible (infected) individuals who have abilities to recognize the disease would break the links of their infected (susceptible) neighbors to prevent the epidemic from further spreading. Simulation results and numerical analyses based on the pairwise approach indicate that the information-driven adaptive process can not only slow down the speed of epidemic spreading, but can also diminish the epidemic prevalence at the final state significantly. In addition, the disease spreading and information diffusion pattern on the lattice as well as on a real-world network give visual representations about how the disease is trapped into an isolated field with the information-driven adaptive process. Furthermore, we perform the local bifurcation analysis on four types of dynamical regions, including healthy, a continuous dynamic behavior, bistable and endemic, to understand the evolution of the observed dynamical behaviors. This work may shed some lights on understanding how information affects human activities on responding to epidemic spreading.","Adaptive model; Bifurcation analysis; Epidemic spreading; Information diffusion","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-12-31","","","Multimedia Computing","","",""
"uuid:9304e5c5-0d01-4b43-8704-fef57bb9700f","http://resolver.tudelft.nl/uuid:9304e5c5-0d01-4b43-8704-fef57bb9700f","City branding in China's Northeastern region: How do cities reposition themselves when facing industrial decline and ecological modernization?","Han, Meiling (Harbin Institute of Technology; Erasmus Universiteit Rotterdam); de Jong, W.M. (TU Delft Organisation & Governance; Fudan University; Erasmus Universiteit Rotterdam); Cui, Zhuqing (Harbin Institute of Technology); Xu, L. (Harbin Institute of Technology); Lu, H. (TU Delft Organisation & Governance); Sun, Baiqing (Harbin Institute of Technology)","","2018","The past decade has seen a surge in the use of city branding, which is used to attract specific target groups of investors, high-tech green firms and talented workforce and reflects a desired shift from old, polluting manufacturing industries to new, clean service industries. Previous studies in the Chinese mega-city regions Pearl River Delta, Yangtze River Delta and Jing-Jin-Ji (region around Beijing and Tianjin) have shown that branding practices of primarily service and innovation oriented cities are largely in line with existing industrial profiles while those which are predominantly manufacturing oriented wish to present themselves as more service and innovation driven. In this contribution, city branding practices are studied in China's three Northeastern provinces Heilongjiang, Jilin and Liaoning which face structural decline because of the presence of many outdated resource-based and heavy industries. The gap between existing profile and branding choices appears not systematic as in China's leading economic regions. Northeastern cities focus more on combining primary, secondary and tertiary industrial patterns than on displacing manufacturing with services. The tertiary sector in these provinces is more administrative and public sector oriented and generates lower value added; it is therefore not significantly more attractive than the primary and secondary ones.","City brand identity; City branding; City label; Developmental pathways; Ecologicalmodernization; North East China","en","journal article","","","","","","","","","","","Organisation & Governance","","",""
"uuid:422284b9-4646-4549-be75-9552564de16e","http://resolver.tudelft.nl/uuid:422284b9-4646-4549-be75-9552564de16e","Simulation of the Flexural Response of Ultrahigh Performance Fiber-Reinforced Concrete with Lattice Fracture Model","Gu, C. (TU Delft Microlab; TU Delft Materials and Environment; Zhejiang University); Wang, Qiannan (Southeast University); Sun, Wei (Southeast University)","","2018","The flexural response of ultrahigh performance fiber-reinforced concrete (UHPFRC) was simulated based on the lattice fracture model. Fiber was modelled as separated beam that was connected to the matrix with interface beams. The simulated results were compared with the experimental results. Deviations occurred at the late stage of the strain-softening period. But both the strain-hardening behavior and multicracking phenomenon were observed in the simulation. The effects of fiber orientation and fiber content were studied with the lattice fracture model. The flexural strength and toughness of UHPFRC improved as the fibers were aligned distributed or the fiber content increased. The proposed model has the potential to help with the materials design of UHPFRC, and the limitations of the model were also discussed in the paper.","","en","journal article","","","","","","","","","","","Microlab","","",""
"uuid:cf8e91f5-3df1-4fb9-8601-e63702a00de3","http://resolver.tudelft.nl/uuid:cf8e91f5-3df1-4fb9-8601-e63702a00de3","Microstructure and hardness of SAC305 and SAC305-0.3Ni solder on Cu, high temperature treated Cu, and graphene-coated Cu substrates","Li, Shengli (Harbin University of Science and Technology); Liu, Y. (TU Delft Electronic Components, Technology and Materials; Harbin University of Science and Technology); Zhang, H. (TU Delft Electronic Components, Technology and Materials; Harbin University of Science and Technology); Cai, Hongming (Harbin University of Science and Technology); Sun, Fenglian (Harbin University of Science and Technology); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2018","In this study, SAC305 and SAC305-0.3Ni solder balls were soldered onto Cu, high temperature treated Cu (H-Cu) and graphene coated Cu (G-Cu) substrates, respectively. The microstructure, the interfacial reaction, and the hardness of the solder joints were investigated. The interfacial intermetallic compound (IMC) is Cu6Sn5 in the solder joints of SAC305/Cu, SAC305/H-Cu, and SAC305/G-Cu. With the addition of 0.3 wt% Ni in the SAC305 solder, the interfacial IMC on Cu, H-Cu, and G-Cu transforms from Cu6Sn5 into (Cu, Ni)6Sn5. The thickness of Cu6Sn5 and (Cu, Ni)6Sn5 is the lowest on G-Cu substrate. Meanwhile, smooth (Cu, Ni)6Sn5 interfacial IMC layers are obtained in SAC305-0.3Ni/H-Cu and SAC305-0.3Ni/G-Cu solder joints. Both the SAC305 and the SAC305-0.3Ni solder bulks have the highest β-Sn content and the lowest concentration of eutectic phases on G-Cu substrate. Consequently, the hardness of the solder bulks on G-Cu is lower than that on the other two kinds of substrates.","Graphene; Hardness; Microstructure; Sn-Ag-Cu; Soldering","en","journal article","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:5b47f226-b284-4198-badb-b0de8f6e4079","http://resolver.tudelft.nl/uuid:5b47f226-b284-4198-badb-b0de8f6e4079","A stochastic process based reliability prediction method for LED driver","Sun, Bo (Guangdong University of Technology); Fan, Xuejun (Lamar University); van Driel, W.D. (TU Delft Electronic Components, Technology and Materials; Philips Lighting Research); Cui, Chengqiang (Guangdong University of Technology); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2018","In this study, we present a general methodology that combines the reliability theory with physics of failure for reliability prediction of an LED driver. More specifically, an integrated LED lamp, which includes an LED light source with statistical distribution of luminous flux, and a driver with a few critical components, is considered. The Wiener process is introduced to describe the randomness of lumen depreciation. The driver's survival probability is described using a general Markov Chain method. The system compact thermal model (physics of failure model) is developed to couple with the reliability methods used. Two scenarios are studied: Scenario S1 considers constant driver's operation temperature, while Scenario S2 considers driver's temperature rise due to lumen depreciation. It has been found that the wide life distribution of LEDs will lead to a large range of the driver's survival probability. The proposed analysis provides a general approach for an electronic system to integrate the reliability method with physics models.","LED driver; LED lamp; Lumen depreciation; Reliability prediction; Stochastic process","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.","","2021-05-28","","","Electronic Components, Technology and Materials","","",""
"uuid:9e26fdb2-c0f3-41e1-856c-7add14d38878","http://resolver.tudelft.nl/uuid:9e26fdb2-c0f3-41e1-856c-7add14d38878","Integrating spatial-anatomical regularization and structure sparsity into SVM: Improving interpretation of Alzheimer's disease classification","Sun, Zhuo (Leiden University Medical Center); Qiao, Yuchuan (Leiden University Medical Center); Lelieveldt, B.P.F. (TU Delft Pattern Recognition and Bioinformatics; Leiden University Medical Center); Staring, M. (TU Delft Pattern Recognition and Bioinformatics; Leiden University Medical Center)","","2018","In recent years, machine learning approaches have been successfully applied to the field of neuroimaging for classification and regression tasks. However, many approaches do not give an intuitive relation between the raw features and the diagnosis. Therefore, they are difficult for clinicians to interpret. Moreover, most approaches treat the features extracted from the brain (for example, voxelwise gray matter concentration maps from brain MRI) as independent variables and ignore their spatial and anatomical relations. In this paper, we present a new Support Vector Machine (SVM)-based learning method for the classification of Alzheimer's disease (AD), which integrates spatial-anatomical information. In this way, spatial-neighbor features in the same anatomical region are encouraged to have similar weights in the SVM model. Secondly, we introduce a group lasso penalty to induce structure sparsity, which may help clinicians to assess the key regions involved in the disease. For solving this learning problem, we use an accelerated proximal gradient descent approach. We tested our method on the subset of ADNI data selected by Cuingnet et al. (2011) for Alzheimer's disease classification, as well as on an independent larger dataset from ADNI. Good classification performance is obtained for distinguishing cognitive normals (CN) vs. AD, as well as on distinguishing between various sub-types (e.g. CN vs. Mild Cognitive Impairment). The model trained on Cuignet's dataset for AD vs. CN classification was directly used without re-training to the independent larger dataset. Good performance was achieved, demonstrating the generalizability of the proposed methods. For all experiments, the classification results are comparable or better than the state-of-the-art, while the weight map more clearly indicates the key regions related to Alzheimer's disease.","Alzheimer's disease; Proximal algorithm; Spatial-anatomical regularization; Structure sparsity; Support vector machine (SVM)","en","journal article","","","","","","","","","","","Pattern Recognition and Bioinformatics","","",""
"uuid:065e62f5-8841-438e-9060-037352e04085","http://resolver.tudelft.nl/uuid:065e62f5-8841-438e-9060-037352e04085","System in package (SiP) technology: Fundamentals, design and applications","Santagata, F. (Guangdong Dongguan Quality Supervision Testing Center); Sun, J. (TU Delft Electronic Components, Technology and Materials); Iervolino, E. (Southern University of Science and Technology); Yu, H. (Southern University of Science and Technology); Wang, F. (Southern University of Science and Technology); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Sarro, Pasqualina M (TU Delft Electronic Components, Technology and Materials); Zhang, Guoyi","","2018","Purpose: The purpose of this paper is to demonstrate a novel 3D system-in-package (SiP) approach. This new packaging approach is based on stacked silicon submount technology. As demonstrators, a smart lighting module and a sensor systems were successfully developed by using the fabrication and assembly process described in this paper. Design/methodology/approach: The stacked module consists of multiple layers of silicon submounts which can be designed and fabricated in parallel. The 3D stacking design offers higher silicon efficiency and miniaturized package form factor. This platform consists of silicon submount design and fabrication, module packaging, system assembling and testing and analyzing. Findings: In this paper, a smart light emitting diode system and sensor system will be described based on stacked silicon submount and 3D SiP technology. The integrated smart lighting module meets the optical requirements of general lighting applications. The developed SiP design is also implemented into the miniaturization of particular matter sensors and gas sensor detection system. Originality/value: SiP has great potential of integrating multiple components into a single compact package, which has potential implementation in intelligent applications.","Gas sensor system; LED module; PM sensor; System-in-package (SiP)","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.","","2021-11-29","","","Electronic Components, Technology and Materials","","",""
"uuid:30d021c4-60ce-41bd-9b1d-c1e0ca64a871","http://resolver.tudelft.nl/uuid:30d021c4-60ce-41bd-9b1d-c1e0ca64a871","Planning Modern Cities in China: Urban Construction Regulations of Concessions in Tianjin (1860-1945)","Sun, Y. (TU Delft OLD History of Architecture & Urban Planning; Tianjin University); Hein, C.M. (TU Delft History, Form & Aesthetics); Song, Kun (Tianjin University); Feng, Lin (Tianjin University)","","2018","Tianjin, one of the so-called Treaty Ports that opened to foreign trade under the unequal treaties was home to nine foreign concessions. In each concession, the foreign powers created urban forms and functions that mirrored practices in their respective home countries. This article explores the consecutive establishment and implementation of regulations in eight out of nine foreign concessions in Tianjin between 1860 and 1945. It firstly provides an overview of regulation types and legislative systems of the concessions. Secondly, it compares these regulations and bylaws with the ones in their home countries. Thirdly, it compares the specific cases of Tianjin concessions with each other. Finally, it places the Tianjin case in the context of other Chinese port city concessions. In conclusion, it argues that the regulations of concessions in Tianjin not only showed a strong influence from their home countries in a top-down setting, but also interacted with each other in a peer-to-peer setting. The circulation of these regulations, within Tianjin and among treaty ports in China, was promoted by governments’ central control, municipal councils’ intervention and individuals’ movements from one place to another.","Treaty Port; Concessions; Modern Tianjin; Regulations","en","conference paper","Delft University of Technology","","","","","","","","","","History, Form & Aesthetics","","",""
"uuid:50a78356-0bd7-49f1-8867-d8cbe96c45e4","http://resolver.tudelft.nl/uuid:50a78356-0bd7-49f1-8867-d8cbe96c45e4","Reliability Prediction of Integrated LED Lamps with Electrolytic Capacitor-Less LED Drivers","Sun, B (Beijing Research Center); Fan, Xuejun (State Key Laboratory of Solid State Lighting; Lamar University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials; Chinese Academy of Sciences; State Key Laboratory of Solid State Lighting)","van Driel, W.D. (editor); van Driel, Willem Dirk (editor); Fan, Xuejun (editor); Zhang, Guo Qi (editor)","2018","This chapter investigates the reliability of the integrated LED lamps with electrolytic capacitor-less LED drivers. Firstly, the impact of the interaction between the degradations of the LED light source and the driver on the lumen depreciation is studied. The electronic-thermal simulation was carried out to obtain the history of temperatures of LED and driver, the driver’s output current, and the luminous flux considering the variations of temperature and current throughout the operation life. It is found that the ultimate lamp’s lifetime is significantly less than the individual lifetimes of the preselected LED and driver. It is concluded that it is necessary to apply the electronic-thermal simulations to predict the lifetime of LED lamps when driver’s lifetime is comparable to the LED’s lifetime. Secondly, this chapter focuses on predicting the catastrophic failure of an electrolytic capacitor-free LED driver during the lumen depreciation process. Electronic-thermal simulations are utilized to obtain the lamp’s dynamic history of temperature and electrical current for two distinct modes: constant current mode (CCM) and the constant optical output (CLO) mode, respectively. A fault tree method is applied to calculate the system’s MTTF, and the LED’s lifetime also is calculated. The CLO mode increases the LED’s current exponentially to maintain the constant light output. As a result, junction temperatures of LEDs, MOSFET, and diode rise significantly, leading a shorter lifetime and MTTF. Compare with the current of the MOSFET, the increased junction temperature has larger effects on the failure rate. The MOSFET contributes more to the driver’s failure rate than the diode. For the CCM mode, junction temperatures increase slightly and have a little shorter lifetime and MTTF.","Lifetime prediction; Mean Time To Failure (MTTF); Maximum likelihood estimation; LED driver; Reliability; Electronic-thermal simulation","en","book chapter","Springer","","","","","","","2021-05-28","","","Electronic Components, Technology and Materials","","",""
"uuid:b52cdb35-e35d-4a99-b93f-313e3e6048af","http://resolver.tudelft.nl/uuid:b52cdb35-e35d-4a99-b93f-313e3e6048af","Manufacture of highly loaded silica-supported cobalt Fischer-Tropsch catalysts from a metal organic framework","Sun, X. (TU Delft ChemE/Catalysis Engineering); Olivos Suarez, A.I. (TU Delft ChemE/Catalysis Engineering); Meijerink, Mark (Universiteit Utrecht); Van Deelen, Tom (Universiteit Utrecht); Ould-Chikh, Samy (King Abdullah University of Science and Technology); Zečević, Jovana (Universiteit Utrecht); de Jong, K.M. (TU Delft Information Management); Kapteijn, F. (TU Delft ChemE/Catalysis Engineering); Gascon, Jorge (TU Delft ChemE/Catalysis Engineering; King Abdullah University of Science and Technology)","","2017","The development of synthetic protocols for the preparation of highly loaded metal nanoparticle-supported catalysts has received a great deal of attention over the last few decades. Independently controlling metal loading, nanoparticle size, distribution, and accessibility has proven challenging because of the clear interdependence between these crucial performance parameters. Here we present a stepwise methodology that, making use of a cobalt-containing metal organic framework as hard template (ZIF-67), allows addressing this long-standing challenge. Condensation of silica in the Co-metal organic framework pore space followed by pyrolysis and subsequent calcination of these composites renders highly loaded cobalt nanocomposites (~ 50 wt.% Co), with cobalt oxide reducibility in the order of 80% and a good particle dispersion, that exhibit high activity, C5 + selectivity and stability in Fischer-Tropsch synthesis.","","en","journal article","","","","","","","","","","","ChemE/Catalysis Engineering","","",""
"uuid:37d758b5-bf35-4a34-83c9-235008eaf116","http://resolver.tudelft.nl/uuid:37d758b5-bf35-4a34-83c9-235008eaf116","Metal-Organic-Framework mediated supported-cobalt catalysts in multiphase hydrogenation reactions","Sun, X. (TU Delft ChemE/Catalysis Engineering)","Kapteijn, F. (promotor); Gascon, Jorge (promotor); Delft University of Technology (degree granting institution)","2017","The production of most industrially important chemicals involves catalysis. Depending on the difference in phases between the catalysts and reactants, one distinguishes homogenous catalysis and heterogeneous catalysis, with the latter being more attractive in real applications, due to the easy separation of products from catalysts and reusing the latter. In spite of the research and development of heterogeneous catalysts for decades, the exploration for catalysts system with outstanding activity, stability and selectivity remains a challenging task. In general, most of the chemical reactions occur on the surface atoms of supported metal (oxide) nanoparticles. Therefore, to address this challenge, current studies generally focus on understanding the relation between the catalytic performance and catalyst properties by controlling the particle size and distribution, and even
the shape of supported nanoparticles, and the interaction between nanoparticles and support. In order to further contribute to this objective, in this thesis we applied metal-organic-frameworks (MOFs) as a sacrificial precursor to produce catalysts for catalytic hydrogenation reactions, important routes for the production of a variety of fine and bulk chemicals in industry.","","en","doctoral thesis","","978-94-028-0808-7","","","","","","","","","ChemE/Catalysis Engineering","","",""
"uuid:7fe64dde-7fb5-4392-8160-da6f7916dc6b","http://resolver.tudelft.nl/uuid:7fe64dde-7fb5-4392-8160-da6f7916dc6b","Estimating geocenter motion and changes in the Earth’s dynamic oblateness from GRACE and geophysical models","Sun, Y. (TU Delft Physical and Space Geodesy)","Klees, R. (promotor); Riva, R.E.M. (copromotor); Delft University of Technology (degree granting institution)","2017","Geocenter motion and changes in the Earth’s dynamic oblateness (J2) are of great importance in many applications. Among others, they are critical indicators of largescale mass redistributions, which is invaluable to understand ongoing global climate change. The revolutionary Gravity Recovery and Climate Experiment (GRACE) satellite mission enables a constant monitoring of redistributing masses within the Earth’s system. However, it still cannot provide reliable time variations in degree-1 coefficients and degree-2 zonal coefficients, which are directly related to geocenter motion and J2 variations.","Geocenter motion; J2; Temporal gravity field variations; Mass transport; Glacial isostatic adjustment; GRACE; Satellite Laser Ranging","en","doctoral thesis","","978-94-6361-016-2","","","","","","","","","Physical and Space Geodesy","","",""
"uuid:1c6002bf-539b-468f-872b-fb5f890711f5","http://resolver.tudelft.nl/uuid:1c6002bf-539b-468f-872b-fb5f890711f5","Research on the mechanical, thermal, induction heating and healing properties of steel slag/steel fibers composite asphalt mixture","Liu, Quantao (Wuhan University of Technology; Chang'an University); Li, Bin (Wuhan University of Technology); Schlangen, E. (TU Delft Materials and Environment); Sun, Yihan (Zhejiang Provincial Institute of Communications Planning, Design and Research); Wu, Shaopeng (Wuhan University of Technology)","","2017","In this paper, steel slag/steel fiber composite asphalt mixture were prepared. The effects of the addition of steel slag and/or steel fibers on the mechanical, thermal, induction heating and healing properties of asphalt mixture were investigated. The results showed that adding steel slag and/or steel fibers improves the water stability, particle loss resistance and fracture energy of asphalt mixtures. The addition of steel fibers increased the thermal conductivity and thermal diffusion of the asphalt mixture, and steel slag showed a reverse effect. Steel slag asphalt mixture cooled more slowly than steel fiber asphalt mixture, which is beneficial to crack healing of asphalt mixture. The composite of steel fibers and steel slag can enhance the induction heating speed, heating homogeneity and thus enhance the induction healing ratio of asphalt mixture. It is concluded that steel slag/steel fibers composite asphalt mixture achieves good mechanical and induction healing properties.","Asphalt mixture; Healing; Induction heating; Steel fiber; Steel slag","en","journal article","","","","","","","","","","","Materials and Environment","","",""
"uuid:e83b184c-c972-402a-a0c6-418222cf11ad","http://resolver.tudelft.nl/uuid:e83b184c-c972-402a-a0c6-418222cf11ad","The Lifetime Prediction of LED Drivers and Lamps","Sun, B. (TU Delft Electronic Components, Technology and Materials)","Zhang, Kouchi (promotor); Delft University of Technology (degree granting institution)","2017","Light-Emitting Diodes (LEDs) have become a very promising alternative lighting source with the main advantages of a longer lifetime and a higher efficiency than traditional ones. However, the LED lamp’s lifetime is compromised by its driver’s reliability. Although extensive studies have been made on the reliability of LEDs, the research on the lifetime prediction for LED drivers, and the interaction of the reliability between LEDs and driver in an LED system is still lacking. This dissertation investigates the lifetime predictions for LED drivers and LED lamps using physics of failure (PoF) based reliability simulations. Various reliability and statistical methods, such as theMonte Carlo method, the fault-tree method, the Markov Chain method, and the Wiener process, are applied and integrated with the electronic-thermal simulation in order to investigate various problems.","LED Driver; LED Lamp; Reliability; Solid state lighting; Lifetime prediction; Electronic-thermal simulation","en","doctoral thesis","","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:b2c3a9a2-0bbf-4e03-bc83-8fb0179dd5f6","http://resolver.tudelft.nl/uuid:b2c3a9a2-0bbf-4e03-bc83-8fb0179dd5f6","Statistically optimal estimation of degree-1 and C20 coefficients based on GRACE data and an ocean bottom pressure model","Sun, Y. (TU Delft Laboratory Geoscience and Remote Sensing); Ditmar, P.G. (TU Delft Physical and Space Geodesy); Riva, R.E.M. (TU Delft Physical and Space Geodesy)","","2017","In this study, we develop a methodology to estimate monthly variations in degree-1 andC20 coefficients by combing Gravity Recovery and Climate Experiment (GRACE) data withoceanic mass anomalies (combination approach).With respect to the method by Swenson et al.,the proposed approach exploits noise covariance information of both input data sets and thusproduces stochastically optimal solutions supplied with realistic error information. Numericalsimulations show that the quality of degree-1 and -2 coefficients may be increased in this wayby about 30 per cent in terms of RMS error.We also proved that the proposed approach can bereduced to the approach of Sun et al. provided that the GRACE data are noise-free and noise inoceanic data is white. Subsequently, we evaluate the quality of the resulting degree-1 and C20coefficients by estimating mass anomaly time-series within carefully selected validation areas,where mass transport is small. Our validation shows that, compared to selected Satellite LaserRanging (SLR) and joint inversion degree-1 solutions, the proposed combination approachbetter complementsGRACE solutions. The annual amplitude of the SLR-based C10 is probablyoverestimated by about 1 mm. The performance of the C20 coefficients, on the other hand, issimilar to that of traditionally used solution from the SLR technique.","Geopotential theory; Global change from geodesy; Reference systems; Satellite geodesy; Satellite gravity; Time variable gravity","en","journal article","","","","","","","","","","","Laboratory Geoscience and Remote Sensing","","",""
"uuid:6cd9173e-7c76-472b-9824-5d3656b0a9b5","http://resolver.tudelft.nl/uuid:6cd9173e-7c76-472b-9824-5d3656b0a9b5","CitRec 2017: International Workshop on Recommender Systems for Citizens","Yang, J. (TU Delft Web Information Systems); Sun, Zhu (Nanyang Technological University); Bozzon, A. (TU Delft Web Information Systems); Zhang, J. (Nanyang Technological University); Larson, M.A. (TU Delft Multimedia Computing; Radboud Universiteit Nijmegen)","","2017","The ""International Workshop on Recommender Systems for Citizens"" (CitRec) is focused on a novel type of recommender systems both in terms of ownership and purpose: recommender systems run by citizens and serving society as a whole.","Citizens; Recommender systems; Smart Cities; Spatio-temporal context-aware recommendation","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Web Information Systems","","",""
"uuid:550b2ad8-8db6-4986-8271-853620a624f8","http://resolver.tudelft.nl/uuid:550b2ad8-8db6-4986-8271-853620a624f8","A novel lifetime prediction for integrated LED lamps by electronic-thermal simulation","Sun, B. (TU Delft Electronic Components, Technology and Materials; State Key Laboratory of Solid State Lighting); Fan, Xuejun (Lamar University; State Key Laboratory of Solid State Lighting); Ye, H. (Chongqing University); Fan, Jiajie (Hohai University; State Key Laboratory of Solid State Lighting); Qian, Cheng (Chinese Academy of Sciences); van Driel, W.D. (Philips Lighting); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2017","In this paper, an integrated LED lamp with an electrolytic capacitor-free driver is considered to study the coupling effects of both LED and driver's degradations on lamp's lifetime. An electrolytic capacitor-less buck-boost driver is used. The physics of failure (PoF) based electronic thermal simulation is carried out to simulate the lamp's lifetime in three different scenarios: Scenario 1 considers LED degradation only, Scenario 2 considers the driver degradation only, and Scenario 3 considers both degradations from LED and driver simultaneously. When these two degradations are both considered, the lamp's lifetime is reduced by about 22% compared to the initial target of 25,000 h. The results of Scenario 1 and 3 are close to each other. Scenario 2 gives erroneous results in terms of luminous flux as the LED's degradation over time is not taken into consideration. This implies that LED's degradation must be taken into considerations when LED and driver's lifetimes are comparable.","Degradation; Electronic-thermal simulation; LED; LED driver; Lifetime prediction","en","journal article","","","","","","Accepted author manuscript","","2019-02-27","","","Electronic Components, Technology and Materials","","",""
"uuid:2199548a-7978-4ebb-98fe-d978435416d7","http://resolver.tudelft.nl/uuid:2199548a-7978-4ebb-98fe-d978435416d7","Metal–Organic Framework Mediated Cobalt/Nitrogen-Doped Carbon Hybrids as Efficient and Chemoselective Catalysts for the Hydrogenation of Nitroarenes","Sun, X. (TU Delft ChemE/Catalysis Engineering); Olivos Suarez, A.I. (TU Delft ChemE/Catalysis Engineering); Oar-Arteta Gonzalez, L. (TU Delft ChemE/Catalysis Engineering); Rozhko, E. (TU Delft ChemE/Catalysis Engineering); Osadchii, D. (TU Delft ChemE/Catalysis Engineering); Bavykina, A.V. (TU Delft ChemE/Catalysis Engineering); Kapteijn, F. (TU Delft ChemE/Catalysis Engineering); Gascon, Jorge (TU Delft ChemE/Catalysis Engineering)","","2017","A Co@N-doped carbon (Co@ NC) hybrid was synthesized by thermal decomposition of the metal–organic framework (MOF) ZIF-67 under N2 atmosphere. These hybrid materials exhibit outstanding catalytic activity and chemoselectivity for the conversion of a wide range of substituted nitroarenes to their corresponding anilines under relatively mild reaction conditions. The high catalytic performance is attributed to the formation of cobalt nanoparticles and to the presence of atomically dispersed Co species in close interaction with nitrogen-doped graphene. Both active species are formed in situ during the pyrolytic transformation of ZIF-67. The catalysts could be reused in consecutive runs, exhibiting a slightly lower activity ascribed to blockage of the active sites by strongly adsorbed reaction species. These results open up a pathway for the design of noble-metal-free solid catalysts for industrial applications.","chemoselectivity; cobalt; deactivation; hydrogenation; N-doped carbon","en","journal article","","","","","","","","2018-04-24","","","ChemE/Catalysis Engineering","","",""
"uuid:a3b18eca-b7d9-4118-8e02-01866d53587a","http://resolver.tudelft.nl/uuid:a3b18eca-b7d9-4118-8e02-01866d53587a","Uncertainty in geocenter estimates in the context of ITRF2014","Riddell, Anna R. (University of Tasmania; Geoscience Australia); King, A. Matt (University of Tasmania); Watson, Christopher S. (University of Tasmania); Sun, Y. (TU Delft Laboratory Geoscience and Remote Sensing); Riva, R.E.M. (TU Delft Physical and Space Geodesy); Rietbroek, Roelof (Universität Bonn)","","2017","Uncertainty in the geocenter position and its subsequent motion affects positioning estimates on the surface of the Earth and downstream products such as site velocities, particularly the vertical component. The current version of the International Terrestrial Reference Frame, ITRF2014, derives its origin as the long-term averaged center of mass as sensed by satellite laser ranging (SLR), and by definition, it adopts only linear motion of the origin with uncertainty determined using a white noise process. We compare weekly SLR translations relative to the ITRF2014 origin, with network translations estimated from station displacements from surface mass transport models. We find that the proportion of variance explained in SLR translations by the model-derived translations is on average less than 10%. Time-correlated noise and nonlinear rates, particularly evident in the Y and Z components of the SLR translations with respect to the ITRF2014 origin, are not fully replicated by the model-derived translations. This suggests that translation-related uncertainties are underestimated when a white noise model is adopted and that substantial systematic errors remain in the data defining the ITRF origin. When using a white noise model, we find uncertainties in the rate of SLR X, Y, and Z translations of ±0.03, ±0.03, and ±0.06, respectively, increasing to ±0.13, ±0.17, and ±0.33 (mm/yr, 1 sigma) when a power law and white noise model is adopted.","geocenter; ITRF origin; noise analysis; reference frame; temporal variability","en","journal article","","","","","","","","2018-01-01","","","Laboratory Geoscience and Remote Sensing","","",""
"uuid:a5262f80-249f-4a66-9dbf-280c5c60a678","http://resolver.tudelft.nl/uuid:a5262f80-249f-4a66-9dbf-280c5c60a678","Improving estimates of water resources in a semi-arid region by assimilating GRACE data into the PCR-GLOBWB hydrological model","Tangdamrongsub, N. (TU Delft Physical and Space Geodesy; The University of Newcastle, Australia); Steele-Dunne, S.C. (TU Delft Water Resources); Gunter, B.C. (TU Delft Physical and Space Geodesy; Georgia Institute of Technology); Ditmar, P.G. (TU Delft Physical and Space Geodesy); Sutanudjaja, Edwin H. (Universiteit Utrecht); Sun, Y. (TU Delft Laboratory Geoscience and Remote Sensing); Xia, Ting (Tsinghua University); Wang, Zhongjing (Tsinghua University)","","2017","An accurate estimation of water resources dynamics is crucial for proper management of both agriculture and the local ecology, particularly in semi-arid regions. Imperfections in model physics, uncertainties in model land parameters and meteorological data, as well as the human impact on land changes often limit the accuracy of hydrological models in estimating water storages. To mitigate this problem, this study investigated the assimilation of terrestrial water storage variation (TWSV) estimates derived from the Gravity Recovery And Climate Experiment (GRACE) data using an ensemble Kalman filter (EnKF) approach. The region considered was the Hexi Corridor in northern China. The hydrological model used for the analysis was PCR-GLOBWB, driven by satellite-based forcing data from April 2002 to December 2010. The impact of the GRACE data assimilation (DA) scheme was evaluated in terms of the TWSV, as well as the variation of individual hydrological storage estimates. The capability of GRACE DA to adjust the storage level was apparent not only for the entire TWSV but also for the groundwater component. In this study, spatially correlated errors in GRACE data were taken into account, utilizing the full error variance-covariance matrices provided as a part of the GRACE data product. The benefits of this approach were demonstrated by comparing the EnKF results obtained with and without taking into account error correlations. The results were validated against in situ groundwater data from five well sites. On average, the experiments showed that GRACE DA improved the accuracy of groundwater storage estimates by as much as 25 %. The inclusion of error correlations provided an equal or greater improvement in the estimates. In contrast, a validation against in situ streamflow data from two river gauges showed no significant benefits of GRACE DA. This is likely due to the limited spatial and temporal resolution of GRACE observations. Finally, results of the GRACE DA study were used to assess the status of water resources over the Hexi Corridor over the considered 9-year time interval. Areally averaged values revealed that TWS, soil moisture, and groundwater storages over the region decreased with an average rate of approximately 0.2, 0.1, and 0.1 cm yr-1 in terms of equivalent water heights, respectively. A particularly rapid decline in TWS (approximately -0.4 cm yr-1) was seen over the Shiyang River basin located in the southeastern part of Hexi Corridor. The reduction mostly occurred in the groundwater layer. An investigation of the relationship between water resources and agricultural activities suggested that groundwater consumption required to maintain crop yield in the growing season for this specific basin was likely the cause of the groundwater depletion.","","en","journal article","","","","","","","","","","","Physical and Space Geodesy","","",""
"uuid:71c944e9-6f27-4dbc-b7d7-328365b1578d","http://resolver.tudelft.nl/uuid:71c944e9-6f27-4dbc-b7d7-328365b1578d","Bound-constrained polynomial optimization using only elementary calculations","de Klerk, E. (TU Delft Discrete Mathematics and Optimization; Tilburg University); Lasserre, Jean B. (Université de Toulouse); Laurent, Monique (Centrum Wiskunde & Informatica (CWI); Tilburg University); Sun, Zhao (Symetrix B.V.)","","2017","We provide a monotone nonincreasing sequence of upper bounds f H k (k≥1) fkH(k≥1) converging to the global minimum of a polynomial f on simple sets like the unit hypercube in ℝn. The novelty with respect to the converging sequence of upper bounds in Lasserre [Lasserre JB (2010) A new look at nonnegativity on closed sets and polynomial optimization, SIAM J. Optim. 21:864–885] is that only elementary computations are required. For optimization over the hypercube [0, 1]n, we show that the new bounds f H k fkH have a rate of convergence in O(1/k − − √ ) O(1/k). Moreover, we show a stronger convergence rate in O(1/k) for quadratic polynomials and more generally for polynomials having a rational minimizer in the hypercube. In comparison, evaluation of all rational grid points with denominator k produces bounds with a rate of convergence in O(1/k2), but at the cost of O(kn) function evaluations, while the new bound f H k fkH needs only O(nk) elementary calculations.
2/CO = 2 and 15 bar. Supported Ru catalysts with particle sizes ranging from 1.7 to 12 nm were prepared by using different Ru loadings and two different high surface area graphite (HSAG) supports to minimize the metal-support interaction. In addition, the effect of promotion with Cs is also evaluated. Microcalorimetric characterization during CO adsorption and XPS reveal a clear interaction between Ru and Cs. The FTS with Ru-based catalysts is, independent of the presence of promoter, highly structure-sensitive when the Ru particle size is under 7 nm. In this range the turnover frequency (TOF) for CO conversion increases with particle size, reaching a near constant value for Ru particles larger than 7 nm. Cs promoted catalysts display lower TOF values than the corresponding unpromoted samples. This somewhat reduced activity is attributed to the stronger CO adsorption on Cs promoted catalysts, as demonstrated by CO adsorption microcalorimetry. Product selectivity depends also on Ru particle size. Selectivity to C5+ hydrocarbons increases with increasing Ru particle size. For Cs-promoted catalysts, the olefin to paraffin ratio in the C2-C4 hydrocarbons range is independent of the Ru particle size, whereas it decreases for the unpromoted catalysts, showing the prevailing influence of the promoter.","","en","journal article","","","","","","","","2018-02-17","","","ChemE/Catalysis Engineering","","",""
"uuid:e26a6583-3fc8-4b7e-8c3e-3655abad4934","http://resolver.tudelft.nl/uuid:e26a6583-3fc8-4b7e-8c3e-3655abad4934","Research Note: Near-surface layer replacement for sparse data: Is interpolation needed?","Sun, Yimin (Aramco Overseas Company B.V.); Verschuur, D.J. (TU Delft ImPhys/Acoustical Wavefield Imaging); Luo, Yi (Saudi Arabian Oil Company)","","2017","Near-surface problem is a common challenge faced by land seismic data processing, where often, due to near-surface anomalies, events of interest are obscured. One method to handle this challenge is near-surface layer replacement, which is a wavefield reconstruction process based on downward wavefield extrapolation with the near-surface velocity model and upward wavefield extrapolation with a replacement velocity model. This requires, in theory, that the original wavefield should be densely sampled. In reality, data acquisition is always sparse due to economic reasons, and as a result in the near-surface layer replacement data interpolation should be resorted to. For datasets with near-surface challenges, because of the complex event behaviour, a suitable interpolation scheme by itself is a challenging problem, and this, in turn, makes it difficult to carry out the near-surface layer replacement. In this research note, we first point out that the final objective of the near-surface layer replacement is not to obtain a newly reconstructed wavefield but to obtain a better final image. Next, based upon this finding, we propose a new thinking, interpolation-free near-surface layer replacement, which can handle complex datasets without any interpolation. Data volume expansion is the key idea, and with its help, the interpolation-free near-surface layer replacement is capable of preserving the valuable information of areas of interest in the original dataset. Two datasets, i.e., a two-dimensional synthetic dataset and a three-dimensional field dataset, are used to demonstrate this idea. One conclusion that can be drawn is that an attempt to interpolate data before layer replacement may deteriorate the final image after layer replacement, whereas interpolation-free near-surface layer replacement preserves all image details in the subsurface.","CFP; Imaging; Layer replacement; Near-surface; Redatuming","en","journal article","","","","","","","","2018-03-19","","","ImPhys/Acoustical Wavefield Imaging","","",""
"uuid:9c9a2153-0f21-4aaf-bcb4-e2a137723486","http://resolver.tudelft.nl/uuid:9c9a2153-0f21-4aaf-bcb4-e2a137723486","Seeing the People’s Republic of China through the Eyes of Montesquieu: Why Sino-European Collaboration on Eco City Development Suffers from European Misinterpretations of “Good Governance”","de Jong, W.M. (TU Delft Organisation & Governance; Fudan University; Erasmus Universiteit Rotterdam); Stout, H. (Erasmus Universiteit Rotterdam); Sun, L. (University of Leeds)","","2017","China faces a number of impressive challenges in dealing with climate change: rising energy use, growing emission levels of greenhouse gases, dangerous levels of air pollution over cities and low resilience against flood and drought. Sustainable urbanization has been adopted as a keyword in handling these challenges. The Chinese central government has undertaken a variety of measures, including the launch of large Sino-European programs to learn from ‘developed nations’. In the wake of these partnerships, a great variety of cross-national and cross-city agreements were signed. Sino-European cooperation does not often run as smoothly as initially hoped because of diverging interests, cultural misunderstandings and practical limitations. In the background, a mismatch in normative conceptions Chinese and European participants have of ‘good governance’ plays a role. In this contribution, insights taken from Montesquieu’s ‘The Spirit of Laws’ regarding checks and balances and trias politica (updated to ‘sextas politica’ for the 21st century) are used to comprehend how the exertion of power is distributed and expected to be distributed differently in Chinese than in European administrative traditions. The article will end with conclusions on how European misconceptions of Chinese governance complicate Sino-European collaboration in sustainable urbanization policies.","sustainable urbanization; Sino-European collaboration; Montesquieu; checks and balances; sextas politica; OA-Fund TU Delft","en","journal article","","","","","","","","","","","Organisation & Governance","","",""
"uuid:a34654cb-a9eb-4d0a-bb75-93971a1750a1","http://resolver.tudelft.nl/uuid:a34654cb-a9eb-4d0a-bb75-93971a1750a1","Flight Extraction and Phase Identification for Large Automatic Dependent Surveillance–Broadcast Datasets","Sun, Junzi (TU Delft Control & Simulation); Ellerbroek, Joost (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2017","AUTOMATIC dependent surveillance–broadcast (ADS-B) [1,2] is widely implemented in modern commercial aircraft and will become mandatory equipment in 2020. Flight state information such as position, velocity, and vertical rate are broadcast by tens of thousands of aircraft around the world constantly using onboard ADS-B transponders. These data are identified by a 24-bit International Civil Aviation Organization (ICAO) address, are unencrypted, and can be received and decoded with simple ground station set-ups. This large amount of open data brings a huge potential for ATM research. Most studies that rely on aircraft flight data (historical or real-time) require knowledge on the flight phase of each aircraft at a given time [3–7]. However, when dealing with large datasets such as from ADS-B, which can contain many tens of thousands of flights, exceptions to deterministic definitions of flight phases are inevitable, due to large variances in climb rate, altitude, velocity, or a combination of these. In this case, instead of using deterministic logic to process and extract flight data based on flight conventions, robust and versatile identification algorithms are required. In this paper, a twofold method is proposed and tested: 1) a machine learning clustering step that can handle large amounts of scattered ADS-B data to extract continuous flights, and 2) a flight phase identification step that can segment flight data of any type of aircraft and trajectory by different flight phases.","","en","journal article","","","","","","","","","","","Control & Simulation","","",""
"uuid:e545569e-9516-4243-a8df-df1c06abe017","http://resolver.tudelft.nl/uuid:e545569e-9516-4243-a8df-df1c06abe017","A Reliability Prediction for Integrated LED Lamp with Electrolytic Capacitor-Free Driver","Sun, B. (TU Delft Electronic Components, Technology and Materials; State Key Laboratory of Solid State Lighting); Fan, Xuejun (Lamar University; State Key Laboratory of Solid State Lighting); Li, Lei (State Key Laboratory of Solid State Lighting); Ye, H. (Chongqing University); van Driel, W.D. (TU Delft Electronic Components, Technology and Materials; Philips Lighting Research); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials; Chinese Academy of Sciences; State Key Laboratory of Solid State Lighting)","","2017","This paper studies the interaction of catastrophic failure of the driver and LED luminous flux decay for an integrated LED lamp with an electrolytic capacitor-free LED driver. Electronic thermal simulations are utilized to obtain the lamp's dynamic history of temperature and current for two distinct operation modes: constant current mode (CCM) and constant light output (CLO) mode, respectively. Driver's mean time to failure (MTTF) and the LED's lifetime in terms of luminous flux are calculated. Under CLO mode, the LED's current increases exponentially to maintain the constant light output. As a result, the junction temperatures of LEDs, MOSFETs, and power diodes in driver rise significantly, leading to a much shorter MTTF and faster luminous flux depreciation. However, under the CCM, the junction temperatures of LEDs, MOSFETs, and diodes change modestly; therefore, the driver's MTTF and LED's luminous flux decay are not affected much by the variation of temperatures during LED's degradation process.","Catastrophic failure; electrolytic capacitor-free driver; electronic simulation; fault tree; LED lamp; lifetime; reliability; thermal simulation","en","journal article","","","","","","Accepted author manuscript","","","","","Electronic Components, Technology and Materials","","",""
"uuid:7db2d2d5-0ab5-4e63-8943-6431818a7fda","http://resolver.tudelft.nl/uuid:7db2d2d5-0ab5-4e63-8943-6431818a7fda","MRLR: Multi-level representation learning for personalized ranking in recommendation","Sun, Zhu (Nanyang Technological University); Yang, J. (TU Delft Web Information Systems); Zhang, Jie (Nanyang Technological University); Bozzon, A. (TU Delft Web Information Systems); Chen, Yu (Nanyang Technological University); Xu, Chi (Singapore Institute of Manufacturing Technology)","Sierra, C. (editor)","2017","Representation learning (RL) has recently proven to be effective in capturing local item relationships by modeling item co-occurrence in individual user's interaction record. However, the value of RL for recommendation has not reached the full potential due to two major drawbacks: 1) recommendation is modeled as a rating prediction problem but should essentially be a personalized ranking one; 2) multi-level organizations of items are neglected for fine-grained item relationships. We design a unified Bayesian framework MRLR to learn user and item embeddings from a multi-level item organization, thus benefiting from RL as well as achieving the goal of personalized ranking. Extensive validation on real-world datasets shows that MRLR consistently outperforms state-of-the-art algorithms.","","en","conference paper","International Joint Conferences on Artificial Intelligence (IJCAI)","","","","","","","","","","Web Information Systems","","",""
"uuid:566304e6-99df-4164-96b3-6f73e6b958d7","http://resolver.tudelft.nl/uuid:566304e6-99df-4164-96b3-6f73e6b958d7","Large-Scale ADS-B Data and Signal Quality Analysis","Verbraak, T.L.; Ellerbroek, Joost (TU Delft Control & Simulation); Sun, Junzi (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2017","To investigate the contradicting findings of previous studies that investigated ADS-B quality, a study was per-formed to analyze the data and signal quality of ADS-B. For this study, a large dataset of raw ADS-B messages was analyzed, regarding the quality of the data and the signal, differentiating between internal and external sources of errors. The conclusions from this analysis show that ADS-B indeed is a promising technology, where aircraft are able to accurately report their navigational parameters, but that external factors (e.g., reception probability and malfunctioning on-board equipment) can cause issues with the usability of ADS-B as a primary means of surveillance.","ADS-B; surveillance; latency; accuracy; update interval; integrity; availability","en","conference paper","","","","","","","","","","","Control & Simulation","","",""
"uuid:aa0f7ba7-5fe7-46b6-880b-fa9004eeaae4","http://resolver.tudelft.nl/uuid:aa0f7ba7-5fe7-46b6-880b-fa9004eeaae4","Modeling aircraft performance parameters with open ADS-B data","Sun, Junzi (TU Delft Control & Simulation); Ellerbroek, Joost (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2017","Open access to flight data from ADS-B (Automatic Dependent Surveillance Broadcast) has provided researchers more insights for air traffic management than aircraft tracking alone. With large quantities of trajectory data collected from a wide range of different aircraft types, it is possible to extract accurate aircraft performance parameters. In this paper, a set of more than thirty parameters from seven distinct flight phases are extracted for common commercial aircraft types. It uses various data mining methods, as well as a maximum likelihood estimation approach to generate parametric models for these performance parameters. All parametric models combined can be used to describe a complete flight that includes takeoff, initial climb, climb, cruise, descent, final approach, and landing. Both analytical results and summaries are shown. When available, optimal parameters from these models are also compared with the Base of Aircraft Data and Eurocontrol aircraft performance database. This research not only presents a comprehensive set of methods for extracting different aircraft performance parameters but also provides a first part of open-source parametric performance models that is ready to be used by the ATM community.","ADS-B; Aircraft performance; Data mining; Maximum likelihood estimation","en","other","","","","","","","","","","","Control & Simulation","","",""
"uuid:7dc6ecdc-28f4-4d07-a08b-494be45d6fb6","http://resolver.tudelft.nl/uuid:7dc6ecdc-28f4-4d07-a08b-494be45d6fb6","Modeling aircraft performance parameters with open ADS-B data","Sun, Junzi (TU Delft Control & Simulation); Ellerbroek, Joost (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2017","Open access to flight data from ADS-B (Automatic Dependent Surveillance Broadcast) has provided researchers more insights for air traffic management than aircraft tracking alone. With large quantities of trajectory data collected from a wide range of different aircraft types, it is possible to extract accurate aircraft performance parameters. In this paper, a set of more than thirty parameters from seven distinct flight phases are extracted for common commercial aircraft types. It uses various data mining methods, as well as a maximum likelihood estimation approach to generate parametric models for these performance parameters. All parametric models combined can be used to describe a complete flight that includes takeoff, initial climb, climb, cruise, descent, final approach, and landing. Both analytical results and summaries are shown. When available, optimal parameters from these models are also compared with the Base of Aircraft Data and Eurocontrol aircraft performance database. This research not only presents a comprehensive set of methods for extracting different aircraft performance parameters but also provides a first part of open-source parametric performance models that is ready to be used by the ATM community.","ADS-B; Aircraft performance; Data mining; Maximum likelihood estimation","en","conference paper","","","","","","","","","","","Control & Simulation","","",""
"uuid:07a919b4-6320-4cdf-a979-b55fa4b6864e","http://resolver.tudelft.nl/uuid:07a919b4-6320-4cdf-a979-b55fa4b6864e","Bayesian Inference of Aircraft Initial Mass","Sun, Junzi (TU Delft Control & Simulation); Ellerbroek, Joost (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2017","Aircraft mass is a crucial piece of information for studies on aircraft performance, trajectory prediction, and many other ATM topics. However, it is a common challenge for researchers who have no access to this proprietary information. Previously, several studies have proposed methods to estimates aircraft weight, most of which are focused on specific parts of the flight. Often due to inaccurate input data or biased assumptions, a significant number of estimates can result outside of the weight limitation boundaries. This paper proposes an approach that makes use of multiple observations to get a better estimate for a complete flight. By looking at flight data from a complete trajectory and calculating aircraft mass at different flight phases based on different methods, together with fuel flow models, multiple observations of aircraft initial mass can then be derived. Using the Bayesian inference method, final estimates can be made with a higher level of confidence.","aircraft mass; weight estimation; Bayesian inference","en","conference paper","","","","","","","","","","","Control & Simulation","","",""
"uuid:cf180450-cf66-4532-9c0d-ff64159b0901","http://resolver.tudelft.nl/uuid:cf180450-cf66-4532-9c0d-ff64159b0901","Ground-based Wind Field Construction from Mode-S and ADS-B Data with a Novel Gas Particle Model","Sun, Junzi (TU Delft Control & Simulation); Vû, Huy; Ellerbroek, Joost (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","","2017","Wind is an important parameter in many air traffic management researches, as it often introduces significant uncertainties in aircraft performance studies and trajectory predictions. Obtaining accurate wind field information has always been a challenge due to the availability of weather sensors. Traditionally, there is no direct method to measure wind data at different altitudes with the exception of weather balloon systems that cannot be easily scaled. On the other hand, aircraft, which rely heavily on atmospheric data, can be part of atmospheric model itself. Aircraft can provide wind and temperature measurements to ground observers. In this paper, aircraft are considered as a moving sensor network established to re-construct the wind field on a larger scale. Based on the powerful open-source tool pyModeS, aircraft ground velocity and airspeed are decoded from ADS-B and Mode-S data respectively. Wind observations are then derived based on the difference of these two vectors. An innovative gas particle model is also developed so that the complete wind field can be constructed continuously based on these observations. The model can generate wind field in real-time and at all flight levels. Furthermore, the confidence of wind at any 4D position can be computed according to the proposed model method. Multiple selfand cross-validations are conducted to ensure the correctness and stability of the model, as well as the resulting wind field. This paper provides a series of novel methods, as well as open-source tools, that enable the research community using simple ADS-B/Mode-S receivers to construct accurate wind fields.","ADS-B; Mode-S; aviation weather; wind modeling; aircraft sensor network; gas particle model","en","conference paper","","","","","","","","","","","Control & Simulation","","",""
"uuid:e3447c1d-4aee-491b-92da-a53dfdb18f19","http://resolver.tudelft.nl/uuid:e3447c1d-4aee-491b-92da-a53dfdb18f19","The Effect of Geometry Parameters on Energy and Thermal Performance of School Buildings in Cold Climates of China","Zhang, A. (Tianjin University); Bokel, R.M.J. (TU Delft Building Physics); van den Dobbelsteen, A.A.J.F. (TU Delft Architectural Engineering +Technology; TU Delft Climate Design and Sustainability); Sun, Y. (Tianjin University); Huang, Qiong (Tianjin University); Zhang, Qi (Tianjin University)","","2017","This paper discusses the role of geometry parameters including building shape, window to wall ratio, room depth, and orientation on the energy use and thermal comfort of school buildings in cold climates of China. The annual total energy demand and summer thermal discomfort time were compared through computer simulations with DesignBuilder. Furthermore, a questionnaire was conducted that related to the students’ subjective preference for various building geometry parameters. Results showed that a maximum of 13.6% of energy savings and 3.8% of thermal comfort improvement when compared to the reference case could be achieved through variations in geometry parameters. The H shape performed the best when the building thermal performance and students’ preferences were considered, as well as the various design options for rchitects. Window to wall ratio, room depth, and orientation should also be carefully addressed in terms of different building types. The results of this study can serve as a reference for architects and school managers in the early design stages of schools in cold climates of China.","school building; geometry parameter; Energy consumption; thermal comfort; geometric preference","en","journal article","","","","","","","","","","Architectural Engineering +Technology","Building Physics","","",""
"uuid:863d7ab7-4a9f-4f99-91da-f286ce669274","http://resolver.tudelft.nl/uuid:863d7ab7-4a9f-4f99-91da-f286ce669274","A computational design exploration platform supporting the formulation of design concepts","Yang, D. (TU Delft Design Informatics; South China University of Technology); Sun, Yimin (South China University of Technology); Di Stefano, D. (ESTECO SpA); Turrin, M. (TU Delft Design Informatics; South China University of Technology)","Turrin, Michela (editor); Peters, Brady (editor); O'Brien, William (editor); Stouffs, Rudi (editor); Dogan, Timur (editor)","2017","The comparison of various competing design concepts during conceptual architectural design is commonly needed for achieving a good final concept. For this, computational design exploration is a key approach. Unfortunately, most
of existing research tends to skip this crucial process, and purely focuses on the late-stage design optimization based on a single concept that, they assume, has been good enough or accepted already. This paper focuses on information or knowledge extracted from a multi-objective design exploration for the formulation of a good geometrical building design concept. To better support the exploration process, a new integration plug-in is developed to integrate parametric modelling software and process integration and optimization software. Through a case study that investigates the daylight and energy performances of a large indoor space, this paper 1) tackles the importance of design exploration on the formulation of a good design concept; 2) presents and shows the usability of the new integration plug-in for supporting the exploration process.","Multi-objective design exploration; Design concepts; Trade-off; Comparison; Top daylighting; Energy; Daylight","en","conference paper","Simulation Councils","","","","","","","","","","Design Informatics","","",""
"uuid:e7a17b41-0a32-43ae-ac6e-c4afb2a3d4b4","http://resolver.tudelft.nl/uuid:e7a17b41-0a32-43ae-ac6e-c4afb2a3d4b4","Effect of Corridor Design on Energy Consumption for School Buildings in the Cold Climate.","Zhang, A. (TU Delft Climate Design and Sustainability; Tianjin University); Sun, Y. (TU Delft OLD History of Architecture & Urban Planning; Tianjin University); Huang, Qiong (Tianjin University); Bokel, R.M.J. (TU Delft Building Physics); van den Dobbelsteen, A.A.J.F. (TU Delft Architectural Engineering +Technology)","","2017","This paper discusses the energy impact of corridor design for school buildings in the cold climate of China. Local school buildings were classified into three types in terms of the corridor design patterns. Architectural related parameters of corridors which could have a potential impact on the energy consumption were summarized and discussed, including form and orientation, temperature control, opaque envelope components, glazing, ventilation and infiltration. The annual heating, cooling, lighting and total energy consumption were compared. Results showed that form and orientation have the most significant influence on building energy consumption while opaque envelope insulation of corridors shows the least effect on energy demand. By combining the most beneficial strategies at each step, this study resulted in a better performing corridor design that increases the energy-saving by around 6% for the double-sided corridor building type and 17% for the one-sided enclosed corridor type of school building respectively.","School building; corridor design; Energy saving; China","en","conference paper","Construction Industry Council","","","","","","","","","Architectural Engineering +Technology","Climate Design and Sustainability","","",""
"uuid:6d2e8e01-3b48-478c-8199-590cd8f323a8","http://resolver.tudelft.nl/uuid:6d2e8e01-3b48-478c-8199-590cd8f323a8","Fibre bridging effect on the Paris relation for mode I fatigue delamination growth in composites with consideration of interface configuration","Yao, L. (Harbin Institute of Technology); Sun, Y. (Harbin Institute of Technology); Alderliesten, R.C. (TU Delft Structural Integrity & Composites); Benedictus, R. (TU Delft Aerospace Structures & Materials); Zhao, M (Northwestern Polytechnical University)","","2017","Fibre bridging can significantly enhance delamination resistance making the use of a single Paris resistance curve to determine fatigue crack growth insufficient. An empirical Paris-type relation has been developed in a previous study to take fibre bridging into account in fatigue delamination growth. This relation was developed by correlating the Paris constants C and n to the amount of fibre bridging. This paper provides a further investigation on the interface configuration effect on fatigue delamination growth, illustrating the significance of fibre bridging. The results demonstrated that more bridging fibres can be generated in a multidirectional interface, making both log(C) and n significantly depend on fibre bridging. Thus, the method proposed in the previous study is further extended to take into account of the interface configuration effect.","","en","journal article","","","","","","","","2019-01-01","","Aerospace Structures & Materials","Structural Integrity & Composites","","",""
"uuid:337ca47c-be33-46d5-a689-f10e37999926","http://resolver.tudelft.nl/uuid:337ca47c-be33-46d5-a689-f10e37999926","Stress ratio dependence of fiber bridging significance in mode I fatigue delamination growth of composite laminates","Yao, L. (Harbin Institute of Technology); Sun, Y. (Harbin Institute of Technology); Zhao, M (Northwestern Polytechnical University); Alderliesten, R.C. (TU Delft Structural Integrity & Composites); Benedictus, R. (TU Delft Aerospace Structures & Materials)","","2017","This paper aims to investigate stress ratio effect on fibre bridging significance in mode I fatigue delamination growth of composite materials. Fatigue resistance curves (R-curves) of different stress ratios are determined and compared with the quasi-static R-curve. The fatigue R-curve of a high stress ratio is similar to the quasi-static results. However, fatigue resistance of a low stress ratio is smaller than quasi-static resistance. These indicate that fibre bridging significance is stress ratio dependent. More bridging fibres can be generated in delamination of a high stress ratio, as compared to that of a low stress ratio. This can lead to fatigue bridging laws are stress ratio dependent and fatigue delamination is block load sequence dependent.","B. Fatigue; B. Delamination; Fibre bridging; A. Polymer-matrix composites (PMCs)","en","journal article","","","","","","","","2019-01-01","","Aerospace Structures & Materials","Structural Integrity & Composites","","",""
"uuid:b3af9467-eaf4-484e-a0b1-8b390ec2f8f9","http://resolver.tudelft.nl/uuid:b3af9467-eaf4-484e-a0b1-8b390ec2f8f9","Coordination of industrial symbiosis through anchoring","Sun, Li (University of Leeds); Spekkink, Wouter (The University of Manchester); Cuppen, E.H.W.J. (TU Delft Organisation & Governance); Korevaar, G. (TU Delft Energie and Industrie)","","2017","This paper aims to contribute to understanding the dynamics of industrial symbiosis. More specifically, we focus on the dynamics of anchoring as they can be observed in the Chinese context of eco-industrial development. We define anchoring as those activities that (typically local) actors perform to create local physical and institutional conditions conducive to the emergence and further development of industrial symbiosis in a specific regional industrial system. We argue that, in the study of industrial symbiosis dynamics, it is conceptually more useful to focus on anchoring as an activity, rather than anchor tenants as actors. Based on a systematic literature review, we distinguish two types of anchoring activities: institutional and physical. We analyze anchoring dynamics in the case of Qijiang Industrial Symbiosis (Chongqing Municipality) in China. We have identified the physical and institutional anchoring activities, the actors responsible for these activities, and how different anchoring activities build on each other over time. Our case study shows that the attempt to bring about industrial symbiosis in the Qijiang industrial park can be described in a richer way than just 'governmental planning'.","Anchoring; China; Dynamics; Industrial symbiosis","en","journal article","","","","","","","","","","","Organisation & Governance","","",""
"uuid:34658b9c-2a0f-410a-a9a7-6c373852164a","http://resolver.tudelft.nl/uuid:34658b9c-2a0f-410a-a9a7-6c373852164a","On the origin of critical temperature enhancement in atomically thin superconductors","Talantsev, E. F. (Victoria University of Wellington); Crump, W. P. (Victoria University of Wellington); Island, J.O. (TU Delft QN/van der Zant Lab; Kavli institute of nanoscience Delft; University of California); Xing, Ying (Peking University; Collaborative Innovation Center of Quantum Matter; China University of Petroleum - Beijing); Sun, Yi (Peking University; Collaborative Innovation Center of Quantum Matter); Wang, Jian (Peking University; Collaborative Innovation Center of Quantum Matter); Tallon, J. L. (Victoria University of Wellington; MacDiarmid Institute for Advanced Materials and Nanotechnology)","","2017","Recent experiments showed that thinning gallium, iron selenide and 2H tantalum disulfide to single/several monoatomic layer(s) enhances their superconducting critical temperatures. Here, we characterize these superconductors by extracting the absolute values of the London penetration depth, the superconducting energy gap, and the relative jump in specific heat at the transition temperature from their self-field critical currents. Our central finding is that the enhancement in transition temperature for these materials arises from the opening of an additional superconducting gap, while retaining a largely unchanged 'bulk' superconducting gap. Literature data reveals that ultrathin niobium films similarly develop a second superconducting gap. Based on the available data, it seems that, for type-II superconductors, a new superconducting band appears when the film thickness becomes smaller than the out-of-plane coherence length. The same mechanism may also be the cause of enhanced interface superconductivity.","Atomically-thin superconductors; Coherence length; Critical currents; FeSe; London penetration depth; Superconducting energy gap; Transition metal dichalcogenides","en","journal article","","","","","","","","","","","QN/van der Zant Lab","","",""
"uuid:ab9f68e7-4a52-44e3-b343-0c917de50d85","http://resolver.tudelft.nl/uuid:ab9f68e7-4a52-44e3-b343-0c917de50d85","Detection of Conversion from Mild Cognitive Impairment to Alzheimer’s Disease Using Longitudinal Brain MRI","Sun, Zhuo (Leiden University Medical Center); van de Giessen, M. (Leiden University Medical Center); Lelieveldt, B.P.F. (TU Delft Pattern Recognition and Bioinformatics; Leiden University Medical Center); Staring, M. (TU Delft Pattern Recognition and Bioinformatics; Leiden University Medical Center)","","2017","Mild Cognitive Impairment (MCI) is an intermediate stage between healthy and Alzheimer’s disease (AD). To enable early intervention it is important to identify the MCI subjects that will convert to AD in an early stage. In this paper, we provide a new method to distinguish between MCI patients that either convert to Alzheimer’s Disease (MCIc) or remain stable (MCIs), using only longitudinal T1-weighted MRI. Currently, most longitudinal studies focus on volumetric comparison of a few anatomical structures, thereby ignoring more detailed development inside and outside those structures. In this study we propose to exploit the anatomical development within the entire brain, as found by a non-rigid registration approach. Specifically, this anatomical development is represented by the Stationary Velocity Field (SVF) from registration between the baseline and follow-up images. To make the SVFs comparable among subjects, we use the parallel transportmethod to align themin a common space. The normalized SVF together with derived features are then used to distinguish between MCIc and MCIs subjects. This novel feature space is reduced using a Kernel Principal Component Analysis method, and a linear support vector machine is used as a classifier. Extensive comparative experiments are performed to inspect the influence of several aspects of our method on classification performance, specifically the feature choice, the smoothing parameter in the registration and the use of dimensionality reduction. The optimal result from a 10-fold cross-validation using 36 month follow-up data shows competitive results: accuracy 92%, sensitivity 95%, specificity 90%, and AUC 94%. Based on the same dataset, the proposed approach outperforms two alternative ones that either depends on the baseline image only, or uses longitudinal information from larger brain areas. Good results were also obtained when scans at 6, 12, or 24 months were used for training the classifier. Besides the classification power, the proposed method can quantitatively compare brain regions that have a significant difference in development between the MCIc and MCIs groups.","Alzheimer’s disease; Conversion; Mild cognitive impairment (MCI); MRI; Non-rigid registration; Parallel transport; Stationary velocity field (SVF); SVM classification","en","journal article","","","","","","","","","","","Pattern Recognition and Bioinformatics","","",""
"uuid:76d1e01c-0690-4a1f-adae-f9844db6fcfc","http://resolver.tudelft.nl/uuid:76d1e01c-0690-4a1f-adae-f9844db6fcfc","Planning of public housing in modern Tianjin (1928–1945)","Sun, Y. (TU Delft OLD History of Architecture & Urban Planning; Tianjin University); Hein, C.M. (TU Delft OLD History of Architecture & Urban Planning); Song, Kun (Tianjin University)","","2017","European, American, and Japanese debates on public housing served as models for those in modern China, and Chinese scholars and professionals, with the support of the KMT (Kuomintang), developed public housing as a sign of innovation in both societal reform and building typology. Using the under-researched case of Tianjin's public housing during the so-called Nanjing Decade (1928–1937) and then again during the Japanese Occupation (1937–1945) as case studies, the paper first explores how journals, books, and foreign-trained Chinese scholars introduced the concept of public housing to China. It then examines five public housing projects that municipal authorities developed for Tianjin, two in the Nanjing Decade and three during the Japanese Occupation. Analysing the sites, architectural designs, and management rules of these projects, the paper argues that the projects in the Nanjing Decade (both planned and realized) mostly targeted poor families, serving to simultaneously solve housing problems, reform society, and police the poor; while the projects during the Japanese Occupation benefited high-income people or the Japanese, and did not play a role in the relief of the local poor, who suffered most from the housing shortage.","Japanese occupation; modern Tianjin; Nanjing decade; Public housing; societal reform","en","journal article","","","","","","","","","","","OLD History of Architecture & Urban Planning","","",""
"uuid:ebf48049-a45c-4d01-b6ea-70359d4a24c3","http://resolver.tudelft.nl/uuid:ebf48049-a45c-4d01-b6ea-70359d4a24c3","A high resolution model of linear trend in mass variations from DMT-2: Added value of accounting for coloured noise in GRACE data","Hashemi Farahani, H. (TU Delft Physical and Space Geodesy); Ditmar, P.G. (TU Delft Physical and Space Geodesy); Miragaia Gomes Inacio, P. (TU Delft Physical and Space Geodesy); Engels, Olga (TU Delft Physical and Space Geodesy); Gunter, B.C. (TU Delft Physical and Space Geodesy; Georgia Institute of Technology); Klees, R. (TU Delft Physical and Space Geodesy); Guo, X. (TU Delft Physical and Space Geodesy; Wuhan University); Guo, Jing (Wuhan University); Sun, Y. (TU Delft Physical and Space Geodesy); Liu, Xianglin (Fugro Intersite B.V.); Zhao, Qile (Wuhan University); Riva, R.E.M. (TU Delft Physical and Space Geodesy)","","2017","We present a high resolution model of the linear trend in the Earth’s mass variations based on DMT-2 (Delft Mass Transport model, release 2). DMT-2 was produced primarily from K-Band Ranging (KBR) data of the Gravity Recovery And Climate Experiment (GRACE). It comprises a time series of monthly solutions complete to spherical harmonic degree 120. A novel feature in its production was the accurate computation and incorporation of stochastic properties of coloured noise when processing KBR data. The unconstrained DMT-2 monthly solutions are used to estimate the linear trend together with a bias, as well as annual and semi-annual sinusoidal terms. The linear term is further processed with an anisotropic Wiener filter, which uses full noise and signal covariance matrices. Given the fact that noise in an unconstrained model of the trend is reduced substantially as compared to monthly solutions, the Wiener filter associated with the trend is much less aggressive compared to a Wiener filter applied to monthly solutions. Consequently, the trend estimate shows an enhanced spatial resolution. It allows signals in relatively small water bodies, such as Aral sea and Ladoga lake, to be detected. Over the ice sheets, it allows for a clear identification of signals associated with some outlet glaciers or their groups. We compare the obtained trend estimate with the ones from the CSR-RL05 model using (i) the same approach based on monthly noise covariance matrices and (ii) a commonly-used approach based on the DDK-filtered monthly solutions. We use satellite altimetry data as independent control data. The comparison demonstrates a high spatial resolution of the DMT-2 linear trend. We link this to the usage of high-accuracy monthly noise covariance matrices, which is due to an accurate computation and incorporation of coloured noise when processing KBR data. A preliminary comparison of the linear trend based on DMT-2 with that computed from GSFC global mascons v01 reveals, among other, a high concentration of the signal along the coast for both models in areas like the ice sheets, Gulf of Alaska, and Iceland.","Coloured noise; DMT-2; GRACE; KBR; Time varying gravity field","en","journal article","","","","","","Accepted Author Manuscript","","2019-02-01","","","Physical and Space Geodesy","","",""
"uuid:d7c06083-3b1c-4d3f-a209-8984569c4a46","http://resolver.tudelft.nl/uuid:d7c06083-3b1c-4d3f-a209-8984569c4a46","Impacts of problem scale and sampling strategy on surrogate model accuracy: An application of surrogate-based optimization in building design","Yang, D. (TU Delft Design Informatics; South China University of Technology); Sun, Y (South China University of Technology); Di Stefano, D. (ESTECO SpA); Turrin, M. (TU Delft Design Informatics; South China University of Technology); Sariyildiz, I.S. (TU Delft Design Informatics; Yasar University)","","2016","Surrogate-based Optimization is a useful approach when the objective function is computationally expensive to evaluate, compared to Simulation-based Optimization. In the surrogate-based method, analytically tractable “surrogate models” (also known as “Response Surface Models — RSMs” or “metamodels”), are constructed and validated for each optimization objective and constraint at relatively low computational cost. They are useful for replacing the time-consuming simulations during the optimization; quickly locating the area where the optimum is expected to be for further search; and gaining insight into the global behavior of the system. Nevertheless, there are still concerns about the surrogate model accuracy and the number of simulations necessary to get a reasonably accurate surrogate model. This paper aims to unveil: 1) the possible impacts of problem scale and sampling strategy on the surrogate model accuracy; and 2) the potential of Surrogatebased Optimization in finding high quality solutions for building envelope design optimization problems. For this purpose, a series of multi-objective optimization test cases that mainly consider daylight and energy performance were conducted within the same time frame. Then, the results were compared, in pair, based on which discussions were made. Finally, the corresponding conclusions were obtained after the comparative study.","multi-objective optimization; surrogate-based optimization; problem scale; sampling strategy; response surface model; design of experiments","en","conference paper","IEEE","","","","","Accepted Author Manuscript","","","","","Design Informatics","","",""
"uuid:90639bc5-8737-4470-9306-c8eb7766be5e","http://resolver.tudelft.nl/uuid:90639bc5-8737-4470-9306-c8eb7766be5e","Optimizing estimates of annual variations and trends in geocentermotion and J2 from a combination of GRACE data and geophysical models","Sun, Y. (TU Delft Laboratory Geoscience and Remote Sensing); Riva, R.E.M. (TU Delft Physical and Space Geodesy); Ditmar, P.G. (TU Delft Physical and Space Geodesy)","","2016","The focus of the study is optimizing the technique for estimating geocenter motion and variations in J2 by combining data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission with output from an Ocean Bottom Pressure model and a Glacial Isostatic Adjustment (GIA) model. First, we conduct an end-to-end numerical simulation study. We generate input time-variable gravity field observations by perturbing a synthetic Earth model with realistically simulated errors. We show that it is important to avoid large errors at short wavelengths and signal leakage from land to ocean, as well as to account for self-attraction and loading effects. Second, the optimal implementation strategy is applied to real GRACE data. We show that the estimates of annual amplitude in geocenter motion are in line with estimates from other techniques, such as satellite laser ranging (SLR) and global GPS inversion. At the same time, annual amplitudes of C10 and C11 are increased by about 50% and 20%, respectively, compared to estimates based on Swenson et al. (2008). Estimates of J2 variations are by about 15% larger than SLR results in terms of annual amplitude. Linear trend estimates are dependent on the adopted GIA model but still comparable to some SLR results.","","en","journal article","","","","","","","","2017-05-09","","","Physical and Space Geodesy","","",""
"uuid:11717f7d-51c9-471b-8f9e-ee1a70e7f032","http://resolver.tudelft.nl/uuid:11717f7d-51c9-471b-8f9e-ee1a70e7f032","Flexible CMOS Single-Photon Avalanche Diode Image Sensor Technology","Sun, P. (TU Delft QID/Ishihara Lab)","Charbon-Iwasaki-Charbon, E. (promotor); Ishihara, R. (promotor); Sarro, Pasqualina M (promotor); Delft University of Technology (degree granting institution)","2016","","single-photon avalanche diode; SOI; flexible substrate; CMOS integration; photon counting and image sensor; 866801","en","doctoral thesis","","978-94-028-0314-3","","","","","","2018-01-01","","","QID/Ishihara Lab","","",""
"uuid:e3003c8a-2b61-4bd8-be6a-38cb739a0970","http://resolver.tudelft.nl/uuid:e3003c8a-2b61-4bd8-be6a-38cb739a0970","Design and performance evaluation of a simplified dynamic model for combined sewer overflows in pumped sewer systems","van Daal-Rombouts, P.M.M. (TU Delft Sanitary Engineering); Sun, Siao; Langeveld, J.G. (TU Delft Sanitary Engineering); Bertrand-Krajewski, J.-L.; Clemens, F.H.L.R. (TU Delft Sanitary Engineering)","","2016","Optimisation or real time control (RTC) studies in wastewater systems increasingly require rapid simulations of sewer systems in extensive catchments. To reduce the simulation time calibrated simplified models are applied, with the performance generally based on the goodness of fit of the calibration. In this research the performance of three simplified and a full hydrodynamic (FH) model for two catchments are compared based on the correct determination of CSO event occurrences and of the total discharged volumes to the surface water. Simplified model M1 consists of a rainfall runoff outflow (RRO) model only. M2 combines the RRO model with a static reservoir model for the sewer behaviour. M3 comprises the RRO model and a dynamic reservoir model. The dynamic reservoir characteristics were derived from FH model simulations. It was found that M2 and M3 are able to describe the sewer behaviour of the catchments, contrary to M1. The preferred model structure depends on the quality of the information (geometrical database and monitoring data) available for the design and calibration of the model. Finally, calibrated simplified models are shown to be preferable to uncalibrated FH models when performing optimisation or RTC studies.","Calibration; Conceptual models; Full hydrodynamic models; Integrated modelling; Monitoring; Urban drainage systems","en","journal article","","","","","","","","2018-06-01","","","Sanitary Engineering","","",""
"uuid:aed4c51f-12a8-45a8-a5ae-3561bf020907","http://resolver.tudelft.nl/uuid:aed4c51f-12a8-45a8-a5ae-3561bf020907","Carbon/H-ZSM-5 composites as supports for bi-functional Fischer-Tropsch synthesis catalysts","Valero Romero, M.J. (Universidad de Málaga); Sartipi, S. (TU Delft ChemE/Catalysis Engineering); Sun, X (TU Delft ChemE/Catalysis Engineering); Rodríguez-Mirasol, J. (Universidad de Málaga); Cordero, T. (Universidad de Málaga); Kapteijn, F. (TU Delft ChemE/Catalysis Engineering); Gascon, Jorge (TU Delft ChemE/Catalysis Engineering)","","2016","Mesoporous H-ZSM-5-carbon composites, prepared via tetrapropylammonium hydroxide (TPAOH) post treatment of H-ZSM-5 followed by deposition of pyrolytic carbon, have been used as the support for the preparation of Co-based Fischer-Tropsch catalysts. The resulting catalysts display an improved performance during Fischer-Tropsch synthesis (FTS), with higher activity, higher selectivity towards C5-C9 (gasoline range) hydrocarbons and lower selectivity towards C1 (and C2) than Co/mesoH-ZSM5 (without pyrolytic carbon). This is due to the weaker metal-support interaction caused by the deposited carbon (as revealed by XPS) leading to a higher reducibility of the Co species. Further, the partial deactivation of the Brønsted acid sites by pyrolytic carbon deposition, as was observed by NH3-TPD, allows the modification of the zeolite acidity. Both the olefin to paraffin (O/P) and the isoparaffin to normal paraffin (I/N) ratios decrease with the increase in the carbon content, opening the door to further tune the catalytic performance in multifunctional FTS operations.","","en","journal article","","","","","","","","","","","ChemE/Catalysis Engineering","","",""
"uuid:e12581e9-2f1d-422e-8464-eb7ee5c22070","http://resolver.tudelft.nl/uuid:e12581e9-2f1d-422e-8464-eb7ee5c22070","Flexible ultrathin-body single-photon avalanche diode sensors and CMOS integration","Sun, P.; Ishihara, R.; Charbon, E.","","2016","We proposed the world’s first flexible ultrathin-body single-photon avalanche diode (SPAD) as photon counting device providing a suitable solution to advanced implantable bio-compatible chronic medical monitoring, diagnostics and other applications. In this paper, we investigate the Geiger-mode performance of this flexible ultrathin-body SPAD comprehensively and we extend this work to the first flexible SPAD image sensor with in-pixel and off-pixel electronics integrated in CMOS. Experimental results show that dark count rate (DCR) by band-to-band tunneling can be reduced by optimizing multiplication doping. DCR by trap-assisted avalanche, which is believed to be originated from the trench etching process, could be further reduced, resulting in a DCR density of tens to hundreds of Hertz per micrometer square at cryogenic temperature. The influence of the trench etching process onto DCR is also proved by comparison with planar ultrathin-body SPAD structures without trench. Photon detection probability (PDP) can be achieved by wider depletion and drift regions and by carefully optimizing body thickness. PDP in frontside- (FSI) and backside-illumination (BSI) are comparable, thus making this technology suitable for both modes of illumination. Afterpulsing and crosstalk are negligible at 2µs dead time, while it has been proved, for the first time, that a CMOS SPAD pixel of this kind could work in a cryogenic environment. By appropriate choice of substrate, this technology is amenable to implantation for biocompatible photon-counting applications and wherever bended imaging sensors are essential.","OA-Fund TU Delft","en","journal article","Optical Society of America","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Microelectronics","","","",""
"uuid:d5a91375-c995-4dcf-b499-c593b80ceac1","http://resolver.tudelft.nl/uuid:d5a91375-c995-4dcf-b499-c593b80ceac1","Plasticity under rough surface contact and friction","Sun, F.","Thijsse, B.J. (promotor); Nicola, L. (promotor)","2016","The ultimate objective of this work is to gain a better understanding of the plastic behavior of rough metal surfaces under contact loading. Attention in this thesis focuses on the study of single and multiple asperities with micrometer scale dimensions, a scale at which plasticity is known to be size dependent. The asperities have very simple geometries, either rectangular or sinusoidal and they are pressed into contact with a rigid platen. The analysis is performed using the discrete dislocation (DD) plasticity method, given its accuracy to describe microscale plasticity and its capability of predicting size effects. In DD, plasticity is modeled as the collective motions of discrete dislocations dislocations, which are modeled as line singularities in an otherwise isotropic linear elastic medium. The dislocation Burgers vector is the material length scale that allows to capture plasticity size effects. In Chapter 2, simulations are performed to investigate the flattening of a sinusoidal surface, for different dimensions and shape of the sinusoid. A size dependent response is found for asperities with the same amplitude-to-period (A/w) ratio. The smaller asperities are more difficult to deform plastically due to the limited dislocation density at the same strain. It is observed that the mean contact pressure can reach values up to about 40 times the yield pressure, thus significantly higher than what is predicted by the classical plasticity theory. This is mainly caused by the fact that the area of intimate contact is discontinuous and therefore the distribution of contact pressure is highly non homogeneous. Smaller contact regions are characterized by a very high stress concentration. The simulation results are rather insensitive to the contact conditions used, i.e. frictionless or sticking. When flattening periodic sinusoidal waves, it is not possible to assess a possible size dependence related to the spacing between asperities, since decreasing asperity spacing also reduces asperity size. Therefore in Chapter 3, simulations are performed for the flattening of an array of equally spaced sinusoidal asperities. This allows to investigate the effect of plastic interaction between neighboring asperities on the contact pressure. It is found that the mean contact pressure necessary to flatten closely spaced asperities is larger than that required to flatten widely separated asperities. The so-called asperity density effect is already present in purely elastic materials, and becomes more pronounced when plasticity is described by discrete dislocations. The origin of the asperity density effect is found to be a combination of plastic strain gradients, dislocation limited plasticity and interaction between plastic zones. In Chapter 4, simulations are performed to investigate the effect of flattening on the subsequent shearing behavior of a rectangular asperity protruding from a large single crystal. The shearing is applied after the pillar is flattened to different depths. In large asperities, i.e. a couple of square micrometers, the dislocations generated during flattening promote early plasticity upon shearing, i.e the contact shear stress is reduced, when plastic deformation takes place upon flattening. However, flattening smaller asperities to the same displacement, instead, does not affect subsequent plastic shearing. Despite there are many dislocations in the asperities, they are closely packed on a few active slip planes and therefore have smaller mobility. The simulations are also performed for on multiple asperities to investigate the effect of spacing on their shearing behavior. It is found that closely spaced asperities are easier to plastically shear than isolated asperities. This effect is mainly triggered by the fact that shearing closely spaced asperities in the elastic regime gives rise to a wide region in the subasperity where the shear stress is large and therefore facilitates dislocation nucleation. This effect fades when asperities are very protruding, and plasticity mainly occurs inside of the asperities. In Chapter 5, simulations are performed to investigate the static frictional behavior of a metal asperity on a large single crystal, in contact with a rigid platen. The focus of this chapter is on understanding the relative importance of plasticity and contact sliding in a single asperity at a scale where plasticity is size dependent. Sliding of a contact point is taken to occur when the shear traction exceeds the normal traction at that point times a friction coefficient. Plasticity initiates through the nucleation of dislocations from Frank-Read sources in the metal and is modeled as the collective motion of edge dislocation. Results show that at large contact pressures and friction coefficients, plasticity controls the frictional behavior of a single asperity. When self-similar asperities of different size are flattened to the same depth while loaded tangentially, there is no trace of a size effect in their frictional behavior. However, when they are submitted to the same contact pressure smaller asperities slide while larger asperities deform plastically.","contact mechanics; rough surface; dislocation dynamics; surface topography; size effect; friction","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","Materials Science and Engineering","","","",""
"uuid:185999ce-41f2-4cac-9c4d-27782df18fbf","http://resolver.tudelft.nl/uuid:185999ce-41f2-4cac-9c4d-27782df18fbf","Carbon/H-ZSM-5 composites as supports for bi-functional Fischer-Tropsch synthesis catalysts","Valero-Romero, M.J.; Sartipi, S.; Sun, X.; Rodríguez-Mirasol, J.; Cordero, T.; Kapteijn, F.; Gascon, J.","","2016","Mesoporous H-ZSM-5–carbon composites, prepared via tetrapropylammonium hydroxide (TPAOH) post treatment of H-ZSM-5 followed by deposition of pyrolytic carbon, have been used as the support for the preparation of Co-based Fischer–Tropsch catalysts. The resulting catalysts display an improved performance during Fischer–Tropsch synthesis (FTS), with higher activity, higher selectivity towards C5–C9 (gasoline range) hydrocarbons and lower selectivity towards C1 (and C2) than Co/mesoH-ZSM5 (without pyrolytic carbon). This is due to the weaker metal–support interaction caused by the deposited carbon (as revealed by XPS) leading to a higher reducibility of the Co species. Further, the partial deactivation of the Brønsted acid sites by pyrolytic carbon deposition, as was observed by NH3-TPD, allows the modification of the zeolite acidity. Both the olefin to paraffin (O/P) and the isoparaffin to normal paraffin (I/N) ratios decrease with the increase in the carbon content, opening the door to further tune the catalytic performance in multifunctional FTS operations.","Gold for Gold; Open Access","en","journal article","RSC Publishing","","","","","","","","Applied Sciences","Chemical Engineering","","","",""
"uuid:94425969-8949-4c68-8dde-0b50607ddcb9","http://resolver.tudelft.nl/uuid:94425969-8949-4c68-8dde-0b50607ddcb9","Pension Reform in China","Liu, T (External organisation); Sun, L. (TU Delft Organisation & Governance)","","2016","","Peer-lijst tijdschrift","en","journal article","","","","","","","","2015-11-07","","","Organisation & Governance","","",""
"uuid:12ba0a88-1916-4a7b-a9f5-d7978984d195","http://resolver.tudelft.nl/uuid:12ba0a88-1916-4a7b-a9f5-d7978984d195","Multivariate spline-based adaptive control of high-performance aircraft with aerodynamic uncertainties","Tol, H.J. (TU Delft Control & Simulation); de Visser, C.C. (TU Delft Control & Simulation); Sun, LG (External organisation); van Kampen, E. (TU Delft Control & Simulation); Chu, Q. P. (TU Delft Control & Simulation)","","2016","In this paper, a new modular adaptive control system is presented to compensate for aerodynamic uncertainties in high-performance flight control systems. This approach combines nonlinear dynamic inversion with multivariate spline-based adaptive control allocation. A new real-time identification routine for multivariate splines is presented to compensate for aerodynamic uncertainties in the control allocation system. This method, indicated as spline-based adaptive nonlinear dynamic inversion, is applied to control an F-16 aircraft subject to significant aerodynamics uncertainties. Simulation results indicate that the new controller can tune itself each time a model error is detected and has superior adaptability compared to an ordinary polynomial-based adaptive controller. Multivariate splines have sufficient flexibility and approximation power to accurately model nonlinear aerodynamics over the entire flight envelope. As a result, the global model remains intact. Although a part of the model is being reconfigured using incoming observations, the remainder of the model remains unchanged and can be used as an a priori source of information. This prevents the occurrence of sudden fundamental changes in the global model structure, which are experienced when using ordinary polynomials.","","en","journal article","","","","","","harvest","","","","","Control & Simulation","","",""
"uuid:2258a93f-997a-48ec-ac20-2d97f0a10965","http://resolver.tudelft.nl/uuid:2258a93f-997a-48ec-ac20-2d97f0a10965","Urban social assistance in China: Transnational diffusion and national interpretation","Liu, Tao (Universität Duisburg-Essen); Sun, L. (TU Delft Organisation & Governance)","","2016","In 1999 the State Council of the People’s Republic of China (PRC) introduced the Regulation on the Minimum Living Standard Scheme (MLSS, or dibao) for urban residents in China. Policy learning from different parts of the world significantly shaped the formation and expansion of the MLSS, and Chinese social policy researchers have drawn conclusions about the experiences of these multiple regions. Through expert interviews, we discovered that the Chinese social assistance scheme has been influenced by the US ideas of “social investment” and “workfare.” Furthermore, the European values of “universal entitlement” and “social citizenship” have also been internalised by the Chinese actors behind the scheme. In addition, Hong Kong’s social assistance scheme has inspired Chinese policymakers to explore a model consisting of various categories that target the country’s enormous special welfare needs. Thus, scholars and policymakers from China have used values and ideas outside China to create a hybrid model of social assistance that is characterised by broad coverage, a low benefit level, and a highly provincial administrative structure.","China; Globalisation; Policy transfer; Social assistance","en","journal article","","","","","","","","","","","Organisation & Governance","","",""
"uuid:faa33dcd-6437-4d93-9e58-83e42f987b84","http://resolver.tudelft.nl/uuid:faa33dcd-6437-4d93-9e58-83e42f987b84","Sub-basin-scale sea level budgets from satellite altimetry, Argo floats and satellite gravimetry: a case study in the North Atlantic Ocean","Kleinherenbrink, M. (TU Delft Physical and Space Geodesy); Riva, R.E.M. (TU Delft Physical and Space Geodesy); Sun, Y. (TU Delft Geoscience and Remote Sensing)","","2016",". In this study, for the first time, an attempt is made to close the sea level budget on a sub-basin scale in terms of trend and amplitude of the annual cycle. We also compare the residual time series after removing the trend, the semiannual and the annual signals. To obtain errors for altimetry and Argo, full variance–covariance matrices are computed using correlation functions and their errors are fully propagated. For altimetry, we apply a geographically dependent intermission bias (Ablain et al., 2015), which leads to differences in trends up to 0.8 mm yr−1 . Since Argo float measurements are non-homogeneously spaced, steric sea levels are first objectively interpolated onto a grid before averaging. For the Gravity Recovery And Climate Experiment (GRACE), gravity fields full variance–covariance matrices are used to propagate errors and statistically filter the gravity fields. We use four different filtered gravity field solutions and determine which post-processing strategy is best for budget closure. As a reference, the standard 96 degree Dense Decorrelation Kernel-5 (DDK5)-filtered Center for Space Research (CSR) solution is used to compute the mass component (MC). A comparison is made with two anisotropic Wiener- filtered CSR solutions up to degree and order 60 and 96 and a Wiener-filtered 90 degree ITSG solution. Budgets are computed for 10 polygons in the North Atlantic Ocean, defined in a way that the error on the trend of the MC plus steric sea level remains within 1 mm yr−1 . Using the anisotropic Wiener filter on CSR gravity fields expanded up to spherical harmonic degree 96, it is possible to close the sea level budget in 9 of 10 sub-basins in terms of trend. Wiener-filtered Institute of Theoretical geodesy and Satellite Geodesy (ITSG) and the standard DDK5-filtered CSR solutions also close the trend budget if a glacial isostatic adjustment (GIA) correction error of 10–20 % is applied; however, the performance of the DDK5-filtered solution strongly depends on the orientation of the polygon due to residual striping. In 7 of 10 sub-basins, the budget of the annual cycle is closed, using the DDK5-filtered CSR or the Wiener-filtered ITSG solutions. The Wiener-filtered 60 and 96 degree CSR solutions, in combination with Argo, lack amplitude and suffer from what appears to be hydrological leakage in the Amazon and Sahel regions. After reducing the trend, the semiannual and the annual signals, 24–53 % of the residual variance in altimetryderived sea level time series is explained by the combination of Argo steric sea levels and the Wiener-filtered ITSG MC. Based on this, we believe that the best overall solution for the MC of the sub-basin-scale budgets is the Wiener-filtered ITSG gravity fields. The interannual variability is primarily a steric signal in the North Atlantic Ocean, so for this the choice of filter and gravity field solution is not really signifi- cant.","","en","journal article","","","","","","","","","","Geoscience and Remote Sensing","Physical and Space Geodesy","","",""
"uuid:1a2062d5-f14c-4ba2-a409-f6160e1d53a4","http://resolver.tudelft.nl/uuid:1a2062d5-f14c-4ba2-a409-f6160e1d53a4","Computational Design for Sport Building","Turrin, M. (TU Delft Design Informatics; South China University of Technology); Yang, D. (TU Delft Design Informatics; South China University of Technology); D'Aquilio, A. (TU Delft Design Informatics); Sileryte, R. (TU Delft Design Informatics; TU Delft Environmental Technology and Design); Sun, Y (South China University of Technology)","","2016","The design of sport buildings has great impact on top-sport as well as on recreational sport-activities. It implies challenging tasks in meeting the performance-requirements. This includes the control of factors like daylight/lighting, air flow, thermal conditions, just to name a few. Such factors impact the performance of athletes and are hard to control in large sport halls; their control is even harder when the public/audience is located within the halls and require different climate conditions. While mechanical installations are often needed during competitions in order to guarantee constant conditions, relaying on mechanical installations during the daily and recreational use of the venues challenges their medium/long term sustainability. Computational form finding approaches can favour the achievement of high-performing and sustainable sport buildings. In this light, the paper tackles the use of Multi-objective and Multidisciplinary design optimization. The paper presents the concept of Multi-objective Multidisciplinary design optimization techniques to support trade-off decisions between multiple conflicting design objectives and interdisciplinary design methodology, during the conceptual design of sport buildings. The proposed method is based on parametric modelling, performance simulation tools and algorithms for computational optimization, for which the paper tackles three specific aspects. First of all, due to the complexity of large sport buildings, the formulation of the optimization and the screening of the related design variables is crucial in order to obtain a meaningful design space, which helps reducing unnecessary computational burden. Secondly, assessing performance based on measurements and analyses is crucial and can be supported by performance simulations tools; however effectively integrating performance simulations tools in the early phase of the design requires new tools. In this light, a customized computational process for the rapid assessment of temperature and airflow patterns is presented. Thirdly, the process requires the combination of design optimization and design exploration, while searching for well-performing solutions. The importance of design exploration is emphasized also for sub-optimal solutions. In order to facilitate the design exploration, the combination of optimization algorithms, multi-variate analysis algorithms and options for exploring design solutions via an interactive dashboard connected to a database are presented. To exemplify the method, specific case studies are developed as collaboration between Delft university of Technology and South China university of Technology.","sport buildings; design optimization; parametric design; multidisciplinary design","en","journal article","","","","","","","","","","","Design Informatics","","",""
"uuid:0de8da1d-8b9f-44a7-a5c2-2f9b52b4a488","http://resolver.tudelft.nl/uuid:0de8da1d-8b9f-44a7-a5c2-2f9b52b4a488","A Parametric Modelling Process for the Integration of Architecture and Structure in Large Multi-functional Sports Hall Design: a Case Study","Pan, W. (TU Delft OLD Structural Design; South China University of Technology); Sun, Yimin (South China University of Technology); Turrin, M. (TU Delft Design Informatics); Paul, J.C.","Kawaguchi, K. (editor); Ohsaki, M. (editor); Takeuchi, T. (editor)","2016","The integration of architectural (functional spaces) and structural design is especially crucial for the conceptual design of large multi-functional sports halls, due to the strict regulations for functional spaces, the requirement of large-span structure, and the complex interrelationships between these two aspects. This on-going research aims at developing a computational method to support this integration during the conceptual design of large sports hall. This paper proposes a parametric modelling process to support a design exploration which is an important part of the computational method. A typical and simplified large multi-functional sports hall is used as an example case to demonstrate this process.","parametric modelling process; Large multi-functional sports hall; functional space; large-span structure; design exploration","en","conference paper","IASS","","","","","","","","","","Design Informatics","","",""
"uuid:af67a6bd-d812-474d-a304-7a594991390b","http://resolver.tudelft.nl/uuid:af67a6bd-d812-474d-a304-7a594991390b","Large-Scale Flight Phase Identification from ADS-B Data Using Machine Learning Methods","Sun, Junzi (TU Delft Control & Simulation); Ellerbroek, Joost (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","Lovell, D. (editor); Fricke, H. (editor)","2016","With the increasing availability of ADS-B transponders on commercial aircraft, as well as the rapidly growing deployment of ground stations that provide public access to their data, accessing open aircraft flight data is becoming easier for researchers. Given the large number of operational aircraft, significant amounts of flight data can be decoded from ADSB messages daily. These large amounts of traffic data can be of benefit in a broad range of ATM investigations that rely on operational data and statistics. This paper approaches the challenge of identifying and categorizing these large amounts of data, by proposing various machine learning and fuzzy logic methods. The objective of this paper is to derive a set of methods and reusable open source libraries for handling the large quantity of aircraft flight data.","machine learning; ATM data; big data; fuzzy logic; BlueSky","en","conference paper","","","","","","","","","","","Control & Simulation","","",""
"uuid:234f1650-d9bd-4985-a70e-2115ac9e5c95","http://resolver.tudelft.nl/uuid:234f1650-d9bd-4985-a70e-2115ac9e5c95","Modeling and Inferring Aircraft Takeoff Mass from Runway ADS-B Data","Sun, Junzi (TU Delft Control & Simulation); Ellerbroek, Joost (TU Delft Control & Simulation); Hoekstra, J.M. (TU Delft Control & Simulation)","Lovell, D. (editor); Fricke, H. (editor)","2016","Aircraft mass is an important parameter in many ways, either to build aircraft performance models, to predict flight trajectories, or to simulate air traffic. Mass data is usually considered as sensitive information for airlines and is, therefore, not disclosed to researchers publicly. In this paper, we use two methods to infer the mass of an aircraft at its takeoff phase. The first is by studying the kinetic model at lift-off moment. The second is to look at the motion of aircraft on the runway at each sample moment to estimate the mass recursively.","aircraft mass; performance modeling; weight estimation; BlueSky","en","conference paper","","","","","","","","","","","Control & Simulation","","",""
"uuid:df467c54-bab6-4f4a-867e-24f1212cb5c6","http://resolver.tudelft.nl/uuid:df467c54-bab6-4f4a-867e-24f1212cb5c6","How can the Gradual Development of More Sustainable Energy Systems Be Integrated in Urban Planning in China?","Wennersten, Ronald; Sun, Q; de Jong, W.M. (TU Delft Organisation & Governance)","","2016","Great efforts have been made in China to reduce coal consumption over the last decade. However, the energy transition to more sustainable energy systems will be gradual and take a longer time than expected. This paper discusses how sustainable development of energy systems on the local level can be gradually achieved. A challenge will be to develop smaller scale projects on the local level where participatory planning processes with cross sectoral planning can be implemented. Another challenge is to bring transdisciplinary academic research closer to the practice","Sustainable Development; Sustainable Development; Sustainable Energy Systems; Urban Planning","en","journal article","","","","","","","","","","","Organisation & Governance","","",""
"uuid:2a30fbba-fd5d-40de-9630-1f72ee874711","http://resolver.tudelft.nl/uuid:2a30fbba-fd5d-40de-9630-1f72ee874711","Precision Recess of AlGaN/GaN with Controllable Etching Rate Using ICP-RIE Oxidation and Wet Etching","Sokolovskij, R. (TU Delft Beijing Delft Institute of Intelligent Science and Technology; TU Delft Electronic Components, Technology and Materials); Sun, J. (Beijing Research Center); Santagata, F. (Peking University; Guangdong Dongguan Quality Supervision Testing Center); Iervolino, E. (Peking University; Guangdong Dongguan Quality Supervision Testing Center); Li, S. (Peking University); Zhang, G.Y. (Peking University); Sarro, Pasqualina M (TU Delft Electronic Components, Technology and Materials); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2016","A method for highly controllable etching of AlGaN/GaN for the fabrication of high sensitivity HEMT based sensors is developed. The process consists of cyclic oxidation of nitride with O2 plasma using ICP-RIE etcher followed by wet etching of the oxidized layer. Previously reported cyclic oxidation-based GaN etching obtained very slow etching rate (∼0.38nm/cycle), limited by oxidation depth. The proposed approach allows fine control of the oxidation enabling the formation of accurately controlled recess of very thin (20∼30nm) barrier layers. With optimized power settings, etch rates from ∼0.6 to ∼11nm/cycle were obtained. AFM results did not show any increase in surface roughness after etching, indicating that surface quality of the etched layer was not affected by the etching process.","AlGaN/GaN; cyclic etch; gate recess; HEMT; HEMT-sensor; ICP-RIE; plasma oxidation; semiconductor sensor","en","journal article","","","","","","","","","","","Beijing Delft Institute of Intelligent Science and Technology","","",""
"uuid:abb54b11-f017-49ca-9305-aad8b951044d","http://resolver.tudelft.nl/uuid:abb54b11-f017-49ca-9305-aad8b951044d","A Flexible 32x32 SPAD Image Sensor with Integrated Microlenses","Sun, P.; Charbon, E.; Ishihara, R.","","2015","The first single-photon avalanche diode (SPAD) image sensor fully integrated on flexible substrate is reported. The design consists of an array of 1024 quenched pixels with CMOS readout and addressing circuitries. The flexible substrate was made compatible with sol-gel polymer, which will be used to imprint microlenses by quartz mold to improve fill factor. The SPAD pixel can operate both in frontside- (FSI) and backside-illumination (BSI) with similar peak photon detection probability (PDP) of 13%. The dark count rate (DCR) could be drastically reduced at a cryogenic temperature. Afterpulsing and cross-talk are negligible at the dead time.","","en","conference paper","International Image Sensor Society","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Quantum Engineering","","","",""
"uuid:d6534414-b0fe-4b6b-af49-3d329f3326af","http://resolver.tudelft.nl/uuid:d6534414-b0fe-4b6b-af49-3d329f3326af","Institute of Poldering: Meadow Under Construction","Van Loon, F.D.; Pouderoijen, M.T.; Alberini, E.; Dijkstra, C.M.; Hagen, S.R.; De Jong, M.; Kiliço?lu, I.D.; Koukouvelou, A.; Mekel, M.L.; Schotting, K.; Shao, S.; Sun, X.; Terzi, O.; De Waal, W.; Van der Wal, I.A.; Zhang, B.","","2015","Booklet of the elective course AR0048 2014/2015 ‘Landscape Architecture ON site - being part of Oerol’, an elective course of the MSc2 - Chair of Landscape Architecture at the TU Delft.","landscape architecture; education; polder; climate change; meadow birds; Oerol; Terschelling","en","book","Chair of Landscape Architecture","","","","","","","","Architecture and The Built Environment","Urbanism","","","","53.385000, 5.320000"
"uuid:62ec8d35-1ca4-40fc-bde2-67e7fc6ba3f9","http://resolver.tudelft.nl/uuid:62ec8d35-1ca4-40fc-bde2-67e7fc6ba3f9","Through-wall imaging by TE and TM hybrid polarization inversion based on FDFD and frequency hopping scheme","Sun, S. (TU Delft Microwave Sensing, Signals & Systems)","","2015","","","en","conference paper","","","","","","","","","","","Microwave Sensing, Signals & Systems","","",""
"uuid:65ba77b0-f060-4d58-a4e1-25366e90c99a","http://resolver.tudelft.nl/uuid:65ba77b0-f060-4d58-a4e1-25366e90c99a","Observed changes in the Earth’s dynamic oblateness from GRACE data and geophysical models","Sun, Y.; Ditmar, P.; Riva, R.","","2015","A new methodology is proposed to estimate changes in the Earth’s dynamic oblateness (?J2 or equivalently, ?5??C20) on a monthly basis. The algorithm uses monthly Gravity Recovery and Climate Experiment (GRACE) gravity solutions, an ocean bottom pressure model and a glacial isostatic adjustment (GIA) model. The resulting time series agree remarkably well with a solution based on satellite laser ranging (SLR) data. Seasonal variations of the obtained time series show little sensitivity to the choice of GRACE solutions. Reducing signal leakage in coastal areas when dealing with GRACE data and accounting for self-attraction and loading effects when dealing with water redistribution in the ocean is crucial in achieving close agreement with the SLR-based solution in terms of de-trended solutions. The obtained trend estimates, on the other hand, may be less accurate due to their dependence on the GIA models, which still carry large uncertainties.","J2; C20; satellite laser ranging; glacial isostatic adjustment; temporal gravity field variations; mass transport","en","journal article","Springer","","","","","","","","Civil Engineering and Geosciences","Geoscience & Remote Sensing","","","",""
"uuid:86cfb715-8f7a-46a0-8e29-1a216a0441b1","http://resolver.tudelft.nl/uuid:86cfb715-8f7a-46a0-8e29-1a216a0441b1","Multi-objective and multidisciplinary design optimization of large sports building envelopes: A case study","Yang, D.; Sun, Y.; Turrin, M.; von Buelow, P.; Paul, J.C.","","2015","Currently, in the conceptual envelope design of sports facilities, multiple engineering performance feedbacks (e.g. daylight, energy and structural performance) are expected to assist architectural design decision-making. In general, it is known as Building Performance Optimization in the conceptual architectural design phase. Essentially, it tends to be a Multi-objective and Multidisciplinary Design Optimization problem. Although the potential of Multi-objective Optimization and Multidisciplinary Design Optimization in handling this problem has been demonstrated in different industrial fields, there are still some significant gaps in their current application to the field of building design. The ultimate goal of our research is to find out an effective and efficient Computational Design Optimization approach, for architects, which is suitable for the conceptual design of sports building envelopes. As parts of the final goal, this paper aims to: (1) set up a meaningful benchmark case and method for the comparison of different Multidisciplinary Design Optimization approaches in future research; (2) propose an integrated Computational Design Optimization process to deal with the benchmark case using the benchmark method; and (3) test the overall process through a hypothetical and simplified case study (i.e. a sports hall with a spherical roof). Important aspects of each objective above are highlighted respectively, and thereby bridging the current gaps. Finally, discussion and future research are given.","computational design optimization; multi-objective optimization; multidisciplinary design optimization; sports building envelopes; building performance optimization; conceptual architectural design; daylight performance; energy performance; structural performance","en","conference paper","","","","","","","","","Architecture and The Built Environment","Architectural Engineering +Technology","","","",""
"uuid:e9ed40ce-d223-48e2-89da-2daa38c6af16","http://resolver.tudelft.nl/uuid:e9ed40ce-d223-48e2-89da-2daa38c6af16","Characterization of Single-Photon Avalanche Diodes in Standard 140-nm SOI CMOS Technology","Lee, M.J.; Sun, P.; Charbon, E.","","2015","We report on the characterization of single-photon avalanche diodes (SPADs) fabricated in standard 140-nm silicon on insulator (SOI) complementary metal-oxide-semiconductor (CMOS) technology. As a methodology for SPAD optimization, a test structure array, called SPAD farm, was realized with several junctions, guard-ring structures, dimensions, etc. In this paper, characterization results of the most promising SOI CMOS SPAD are compared with state-of-the-art results reported in the literature.","avalanche photodiode (APD); backside illumination (BSI); CMOS; silicon; silicon on insulator (SOI); single-photon avalanche diode (SPAD); standard SOI CMOS technology","en","conference paper","","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Quantum Engineering","","","",""
"uuid:aa1eb6b1-3bac-416c-a392-192098921ea1","http://resolver.tudelft.nl/uuid:aa1eb6b1-3bac-416c-a392-192098921ea1","A first single-photon avalanche diode fabricated in standard SOI CMOS technology with a full characterization of the device","Lee, M.J.; Sun, P.; Charbon, E.","","2015","This paper reports on the first implementation of a single-photon avalanche diode (SPAD) in standard silicon on insulator (SOI) complementary metal-oxide-semiconductor (CMOS) technology. The SPAD is realized in a circular shape, and it is based on a P+/N-well junction along with a P-well guard-ring structure formed by lateral diffusion of two closely spaced N-well regions. The SPAD electric-field profile is analyzed by means of simulation to predict the breakdown voltage and the effectiveness of premature edge breakdown. Measurements confirm these predictions and also provide a complete characterization of the device, including current-voltage characteristics, dark count rate (DCR), photon detection probability (PDP), afterpulsing probability, and photon timing jitter. The SOI CMOS SPAD has a PDP above 25% at 490-nm wavelength and, thanks to built-in optical sensitivity enhancement mechanisms, it is as high as 7.7% at 850-nm wavelength. The DCR is 244 Hz/?m2, and the afterpulsing probability is less than 0.1% for a dead time longer than 200 ns. The SPAD exhibits a timing response without exponential tail and provides a remarkable timing jitter of 65 ps (FWHM). The new device is well suited to operate in backside illumination within complex three-dimensional (3D) integrated circuits, thus contributing to a great improvement of fill factor and jitter uniformity in large arrays.","avalanche photodiodes (APDs); detectors; integrated optics devices; low light level; optical sensing and sensors; photodetectors; photodiodes; photomultipliers; photon counting; semiconductors; sensors; silicon; three-dimensional fabrication; OA-Fund TU Delft","en","journal article","Optical Society of America","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Microelectronics","","","",""
"uuid:5779af2f-a1db-4fe0-a00e-e18f5d6d1db2","http://resolver.tudelft.nl/uuid:5779af2f-a1db-4fe0-a00e-e18f5d6d1db2","A new robust design for imperfection sensitive stiffened cylinders used in aerospace engineering","Liang, K.; Zhang, Y.; Sun, Q.; Ruess, M.","","2015","A knock-down factor is commonly used to take into account the obvious decline of the buckling load in a cylindrical shell caused by the inevitable imperfections. In 1968, NASA guideline SP-8007 gave knock-down factors which rely on a lower-bound curve taken from experimental data. Recent research has indicated that the NASA knock-down factors are inclined to produce very conservative estimations for the buckling load of imperfect shells, due to the limitations of the computational power and the experimental skills available five decades ago. A novel knock-down factor is proposed composed of two parts for the metallic stiffened cylinders. A deterministic study is applied to achieve the first part of the knock-down factor considering the measured geometric imperfection, the other types of imperfections are considered in the second part using a stochastic analysis. A smeared model is used to achieve the implementation of the measured geometric imperfection for the stiffened cylinder. This new robust and less conservative design for the stiffened cylinders is validated by using test results","knock-down factor; NASA guideline SP-8007; stiffened cylinder; stochastic analysis; smeared model","en","journal article","Springer","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:67b34b4a-4116-4369-a4c4-bc956213a9c3","http://resolver.tudelft.nl/uuid:67b34b4a-4116-4369-a4c4-bc956213a9c3","Distinct mechanisms regulating mechanical force-induced Ca2+ signals at the plasma membrane and the ER in human MSCs","Kim, T.J.; Joo, C.; Seong, J.; Vafabakhsh, R.; Botvinick, E.L.; Berns, M.W.; Palmer, A.E.; Wang, N.; Ha, T.; Jakobsson, E.; Sun, J.; Wang, Y.","","2015","It is unclear that how subcellular organelles respond to external mechanical stimuli. Here, we investigated the molecular mechanisms by which mechanical force regulates Ca2+ signaling at endoplasmic reticulum (ER) in human mesenchymal stem cells. Without extracellular Ca2+, ER Ca2+ release is the source of intracellular Ca2+ oscillations induced by laser-tweezer-traction at the plasma membrane, providing a model to study how mechanical stimuli can be transmitted deep inside the cell body. This ER Ca2+ release upon mechanical stimulation is mediated not only by the mechanical support of cytoskeleton and actomyosin contractility, but also by mechanosensitive Ca2+ permeable channels on the plasma membrane, specifically TRPM7. However, Ca2+ influx at the plasma membrane via mechanosensitive Ca2+ permeable channels is only mediated by the passive cytoskeletal structure but not active actomyosin contractility. Thus, active actomyosin contractility is essential for the response of ER to the external mechanical stimuli, distinct from the mechanical regulation at the plasma membrane.","","en","journal article","eLife Sciences Publications","","","","","","","","Applied Sciences","BN/Bionanoscience","","","",""
"uuid:b5298f37-eeb3-47f2-b43c-e03c016eae79","http://resolver.tudelft.nl/uuid:b5298f37-eeb3-47f2-b43c-e03c016eae79","Distinct mechanisms regulating mechanical force-induced Ca2+ signals at the plasma membrane and the endoplasmic reticulum in human mesenchymal stem cells","Kim, SH (University of Illinois); Joo, C. (TU Delft BN/Chirlmin Joo Lab); Seong, A (External organisation); Vafabakshsh, A (External organisation); Botvinick, A (External organisation); Berns, A (External organisation); Palmer, TA (External organisation); Wang, Z. (External organisation); Ha, Seungkyu; Jakobsson, ME; Sun, M (External organisation)","","2015","It is unclear that how subcellular organelles respond to external mechanical stimuli. Here, we investigated the molecular mechanisms by which mechanical force regulates Ca2+ signaling at endoplasmic reticulum (ER) in human mesenchymal stem cells. Without extracellular Ca2+, ER Ca2+ release is the source of intracellular Ca2+ oscillations induced by laser-tweezer-traction at the plasma membrane, providing a model to study how mechanical stimuli can be transmitted deep inside the cell body. This ER Ca2+ release upon mechanical stimulation is mediated not only by the mechanical support of cytoskeleton and actomyosin contractility, but also by mechanosensitive Ca2+ permeable channels on the plasma membrane, specifically TRPM7. However, Ca2+ influx at the plasma membrane via mechanosensitive Ca2+ permeable channels is only mediated by the passive cytoskeletal structure but not active actomyosin contractility. Thus, active actomyosin contractility is essential for the response of ER to the external mechanical stimuli, distinct from the mechanical regulation at the plasma membrane.","","en","journal article","","","","","","","","","","","BN/Chirlmin Joo Lab","","",""
"uuid:bf0babd8-2e6d-40f5-b805-a629a4160ae3","http://resolver.tudelft.nl/uuid:bf0babd8-2e6d-40f5-b805-a629a4160ae3","Chaotic Dynamics in Smart Grid and Suppression Scheme via Generalized Fuzzy Hyperbolic Model","Sun, Q.; Wang, Y.; Yang, J.; Qiu, Y.; Zhang, H.","","2014","This paper presents a method to control chaotic behavior of a typical Smart Grid based on generalized fuzzy hyperbolic model (GFHM). As more and more distributed generations (DG) are incorporated into the Smart Grid, the chaotic behavior occurs increasingly. To verify the behavior, a dynamic model which describes a power system with DG is presented firstly. Then, the simulation result shows that the power system can lead to chaos under certain initial conditions. Based on the universal approximation of GFHM, we confirm that the chaotic behavior could be suppressed by a new controller, which is designed by means of solving a linear matrix inequality (LMI). This approach could make a good application to suppress the chaos in Smart Grid. Finally, a numerical example is given to demonstrate the effectiveness of the proposed chaotic suppression strategy.","","en","journal article","Hindawi","","","","","","","","Mechanical, Maritime and Materials Engineering","Delft Center for Systems and Control","","","",""
"uuid:89455d9a-fb38-42bf-b1db-03a8a5104bcf","http://resolver.tudelft.nl/uuid:89455d9a-fb38-42bf-b1db-03a8a5104bcf","Model and Sensor Based Nonlinear Adaptive Flight Control with Online System Identification","Sun, L.G.","Mulder, M. (promotor); Chu, Q.P. (promotor)","2014","Consensus exists that many loss-of-control (LOC) in flight accidents caused by severe aircraft damage or system failure could be prevented if flight performance could be recovered using the valid and remaining control authorities. However, the safe maneuverability of a post-failure aircraft will inevitably be reduced due to the malfunction. Non-conventional control strategies which rely on modern control techniques and computational power are essential to control systems in post-failure flight conditions to extract the most from the reduced, remaining aircraft control authorities and restore the flight performance of an aircraft or achieve a safe landing. One such non-conventional control strategy is called active fault tolerant flight control (FTFC), which is designed to detect changes in an aircraft's dynamics caused by structural, actuator, or sensor failure and accommodate the damage or failure using an adaptive reconfiguration mechanism. The active FTFC technique is able to deal with unanticipated and multiple simultaneous failures. The overall architecture of an active FTFC system ideally should consist of a fault detection and diagnosis (FDD) module, a state reconstruction unit, a reconfigurable control component, a control allocation unit and a flight envelope protection (FEP) unit. Generally speaking, FTFC systems can be classified into two types: model-based FTFC systems and model-free FTFC systems, according to whether any of the system's components require an aerodynamic model at their core or not. A model-based FTFC system contains an aerodynamic model identification (AMI) module, which supplies an accurate aircraft model to an indirect adaptive nonlinear controller in the reconfigurable control block, to a dynamic flight envelope determination algorithm in an FEP unit, or to an FDD unit. An aerodynamic model identification approach using a physical, interpretable modeling structure can detect and even quantify structural failures occurring in the aircraft structure or one of the control surfaces by monitoring changes in stability derivatives and control derivatives. There are many candidate control approaches which can achieve reconfiguration when designing a reconfigurable flight controller. These reconfigurable control methods may rely on many different reconfiguration mechanisms ranging from switching, model following, matching to adaptive compensation. These methods include nonlinear adaptive control which achieves reconfiguration through compensation, and this method is receiving increasing attention in the flight control aerospace research community. Nonlinear adaptive control is divided into direct adaptive control and indirect adaptive control, the difference is that the latter requires an online system model. Indirect adaptive control is also called model-based or modular adaptive control, which has some advantages over the direct adaptive control and other model-free control methods. One advantage is that a modular control approach has the potential to yield a more efficient controller which requires less control effort. Such an efficient controller can be achieved by maintaining useful damping terms of an identified system model in the closed-loop system. This is attributed to the good properties of many control design techniques such as backstepping such that the dynamics of an original system can be chosen to be canceled or maintained during a controller design process. Modular adaptive control also has an inherited shortcoming, it can only guarantee input-to-state stability, i.e. modular adaptive control cannot guarantee the stability of the overall closed-loop system because its stability proof relies on the certainty equivalence principle. The weakness of the certainty equivalence principle, i.e., convergence problem of the model parameters, can be improved by enhancing model accuracy or reliability, to do this, it becomes critical to develop advanced, powerful aerodynamic model identification approaches capable of capturing changes in flight dynamics either during a high maneuvering flight mission or a post-failure condition. Flight envelope protection is a necessary technique that should be applied by controller designers to prevent LOC incidents, taking into account highly maneuvering flight tasks and/or highly perturbed flight conditions due to the ongoing failure. An FEP component should provide a pilot with a safe flight envelope and pose constraints on the reference commands fed to an internal controller to make the commands achievable. An aerodynamic model that is valid over an entire flight envelope plays a crucial role in full-envelope modular adaptive control and flight envelope protection. A globally valid model is required for modular adaptive control to enable the designed controller to work properly in a large operating range. Once estimated, the global model in a model-based adaptive control method can be stored for later re-use when the same flight condition is revisited. Except being needed by a model-based controller, an accurate aerodynamic model is also required for flight envelope protection. Naturally, the estimated aerodynamic model has to be valid for the current aircraft configuration over the entire flight envelope to enable an evolution algorithm to estimate the boundary of the safe flight envelope for the current flight condition. However, only a limited number of model identification approaches are suited for estimating a globally valid aerodynamic model, and each existing possible candidate has variant shortcomings or limitations which make it hard to apply directly to identify an aircraft model. For example, neural networks usually yield a nontransparent model structure which is hard to interpret using physical knowledge of the system, and they commonly encounter a convergence problem. Most kernel methods fall into the nonparametric type of methods, which by nature need as many kernels as the data points under evaluation. It should be kept in mind that only equation-error type model identification methods were investigated in the work reported here. The assumption was made that a sufficiently accurate estimation of aircraft states was available. An alternate method to the modular adaptive reconfigurable control approach is the acceleration measurements-based incremental nonlinear control (AMINC) method. An accurate estimation of an aircraft is hard to achieve during a high maneuvering moment or at a transient period when the flight performance is highly perturbed due to aircraft failure. Incremental nonlinear controllers such as incremental nonlinear dynamic inversion (INDI), incremental backstepping (IBKS) and sensor-based backstepping (SBB) are suited for reconfigurable flight control designs in the sense that they do not require complete aircraft model knowledge. The main research question for the research presented here was: How can an advanced fault-tolerant flight control system be designed to increase the survivability of an aircraft? This led to two subsidiary questions: (1). How can the candidate function approximation methods, i.e. multivariate simplex B-splines and kernel methods, be improved in terms of approximation accuracy and computational efficiency, to meet the need of model-based adaptive control and online flight envelope protection? (2). What are the benefits of using an acceleration measurements-based control approach, i.e., the sensor based backstepping, as an alternative to a model-based adaptive control approach, when designing a reconfigurable flight controller to deal with aircraft failures in a generic fault-tolerant flight control (FTFC) system? With regard to reconfigurable control, the identified model should enable the controller to achieve active reconfiguration and restore the control performance. To answer these questions, four different global model identification methods and two nonlinear incremental adaptive controllers were developed. Two model identification methods use a parametric model structure namely standard multivariate simplex B-splines. The focus was placed on how to achieve fast parameter estimation during the research process for these two methods. In the third identification method, a new model structure called tensor-product simplex B-splines was extended from a single dimension case to a multidimensional case, with a focus on demonstrating the advantage of this new compound model structure in terms of the flexibility in model structure selection, computational efficiency and approximation power. The fourth method uses a kernel type model structure which is also parametric. The new recursive kernel approach was developed by combining a classical recursive kernel method with a novel support vector regression approach. A model identification method using standard multivariate simplex B-splines has many advantages, it can avoid the over-fitting problem which occurs with an ordinary polynomial method using a triangulation technique. The approximation power of a simplex B-spline based method is determined by the per-simplex polynomial order and smoothness order, and can be increased by increasing the density of the subdomains in a triangulation. This simplex B-spline based function approximation method guarantees that its output is bounded by the maximum and minimum B-coefficients, this facilitates its certification for future real life applications. The linear regression formulation of the simplex B-spline based method allows for applying most of the constrained recursive parameter estimation methods. Furthermore, the simplex B-spline based method has a sparse property, which can lead to high computational efficiency by adopting distributed computation or other modern computing techniques. However, a simplex B-spline method can easily yield a large amount of unknown parameters if the function dimension exceeds 4, which results in a high computational load considering the smoothness maintaining and covariance matrix updating. To enhance the computational efficiency of the model identification methods using simplex B-splines, two recursive linear-regression model identification methods were developed in this thesis: a substitution-based multivariate simplex B-spline (SB-MVSB) method and a recursive sequential multivariate simplex B-spline (RS-MVSB) method. In the SB-MVSB method, an efficient recursive solver is developed for a constrained linear regression problem when using simplex B-splines. The constrained linear regression problem is converted into a constraint-free linear regression problem using a general solution for the equality constraints. This transformation was shown to reduce the scale of the identification problem in terms of the number of unknown parameters, and thus the computational load required for the model identification method can be reduced. The RS-MVSB method consists of two consecutive procedures at one model evolution step. The first procedure achieves updating of a local model covering the current data point instead of a global model. The requirement of updating a complete covariance matrix is avoided by only updating one local model, and therefore the computational efficiency of this method is greatly enhanced. The second procedure guarantees a smooth transition between this local model and its neighboring local models. The computational complexity of SB-MVSB and RS-MVSB was given from a mathematician point of view, then, they were validated using simulated flight test data generated using a high-fidelity nonlinear model of an F-16 aircraft. Simulation results showed that both methods can achieve higher approximation accuracy than ordinary polynomial based methods, and both can be many, e.g. 10, times faster than an equality constraint recursive least squares based MVSB (ECRLS-MVSB) method. The second feature of these two methods facilitates their future onboard applications. Tensor-product simplex (TPS) B-splines provide a compound structure, which provide more flexibility than a standard simplex B-spline model during model structure selection. Using TPS B-splines, different dimension of inputs can be treated differently depending on their characteristics determined from a priori knowledge. In the work presented in this thesis, the TPS B-spline concept was extended from a single dimension case into a more general multidimensional case. Compared to standard simplex B-splines, TPS B-splines can make better use of a priori model knowledge. By reducing many unnecessary basis polynomials from the regression vector, TPS B-splines have the potential to lead to a lower computational load than standard simplex B-splines. The TPS B-spline method was validated using a data set generated from a high-fidelity nonlinear F-16 model. Simulation results showed that TPS B-splines can yield higher approximation power than standard simplex B-splines with less B-coefficients. Two similar recursive parametric kernel methods namely weight varying least squares support vector regression (WV-LSSVR) and Gaussian process kernel based LSSVR (GPK-LSSVR) were developed for aerodynamic model identification in this thesis. The focus of this work was enhancing the approximation power of a recursive parametric kernel method by choosing an optimal set of kernels for the kernel scheme. An offline method called improved recursive reduced LSSVR (IRR-LSSVR) was used to determine optimal kernels for a classical recursive kernel method. The new kernel method was validated using a series of public available benchmark data sets well known to researchers from the field of pattern recognition. GPK-LSSVR showed a higher approximation power than WV-LSSVR, and both of them showed a higher approximation power than a classical recursive kernel method based on k-means clustering. A novel type of acceleration measurements-based incremental flight control laws was investigated with the aim of providing a reconfigurable control unit with a powerful non-conventional flight control approach which could accommodate sudden structural or actuator failures occurring in an aircraft. The preferred model-free, incremental control approach used in this thesis was the SBB approach, which was initially developed for control designs of nonlinear nonaffine-in-control systems. The SBB approach achieves an accurate reference command tracking performance by approximate dynamic inversion. The SBB approach was extended to deal with sudden model changes in an aircraft caused by structural or actuator failures. A hybrid two-loop angular controller and a joint two-loop angular controller were designed for the RECOVER model. In the hybrid two-loop angular controller, the angular control loop was designed using a nonlinear dynamic inversion (NDI) control law, and the angular rate loop controller using the SBB approach. In the joint two-loop angular controller, the overall controller was designed using a backstepping technique with each loop stabilized recursively. Both angular controllers were validated using the RECOVER model with a focus on dealing with perturbed aircraft flight performance caused by failures. Two benchmark fault scenarios were selected: a rudder runaway case and a flight 1862 engine separation scenario. Simulation results showed that both control setups can guarantee the safety of the post-failure aircraft and achieve a proper reference tracking performance. In comparison with the hybrid NDI/SBB angular controller, the joint SBB angular controller resulted in a better reference tracking performance for the sideslip angle, especially in the engine separation case. An SBB controller contains a time scale parameter, other incremental control laws such as incremental NDI (INDI) and incremental backstepping (IBKS) involve a control effectiveness matrix. Before we can investigate how the time scale parameter or a control effectiveness matrix affect the control performance of an incremental flight controller, the parameter variations of a control effectiveness matrix need to be estimated and analyzed. The TPS B-spline method and an immersion and invariance (I&I) method were chosen to estimate a control effectiveness matrix for an F-16 aircraft. Although the I&I approach initially was not aimed at high modeling accuracy, it was assumed in this thesis that it is able to estimate the changing trend of the control derivatives. Simulation results showed that TPS B-splines capture the changes in the control derivatives better than the I&I approach in terms of consistency. For F-16, the control effectiveness matrix does not evidently affect the control performance of an incremental flight controller when a flight maneuver is moderate in terms of the variation of angle of attack and airspeed. Further research on modular adaptive reconfigurable control is required, for example incorporating the SB-MVSB method or the WV-LSSVR method into control designs to further check how well they are suited for modular adaptive control in terms of approximation power and onboard computational efficiency. Further research on acceleration measurements based reconfigurable control should include tests on the SIMONA simulator, realistic test-flight with UAV and research aircraft.","Fly-by-wire; Aerodynamic model; Adaptive control; Fault tolerant; Reconfiguration; Flight envelope protection; Simplex spline theory","en","doctoral thesis","Ipskamp Drukkers, Enschede, The Netherlands","","","","","","","","Aerospace Engineering","Control and Simulation","","","","51.987, 4.377"
"uuid:5d83f529-e074-4a30-b00b-b11a3d23dabd","http://resolver.tudelft.nl/uuid:5d83f529-e074-4a30-b00b-b11a3d23dabd","Relative Navigation for Satellite Formation Flying based on Radio Frequency Metrology","Sun, R.","Gill, E. (promotor)","2014","To increase mission return, utilizing two or more spacecraft instead of one may sometimes be superior. This is especially true when a large spaceborne instrument needs to be created through larger and configurable baselines, such as telescopes and interferometers. However, coordinating the alignment of the individual components of such a spaceborne instrument on separate spacecraft (involving the estimation and control of baselines) will require a high level of accuracy for relative navigation and control. The increasing demand of such science missions or challenges on complex functions such as rendezvous and docking calls for high accuracy levels of ranging at centimeter or even millimeter levels. The objective of this research is to investigate key technologies of developing a relative navigation system based on radio-frequency (RF) metrology. This RF-based system inherits Global Navigation Satellite System (GNSS) technologies through transmission and reception of locally generated GNSS-like pseudo random noise (PRN) ranging codes and carrier phases via inter-satellite links. This enables operation, e.g., in high Earth orbits where GNSS constellations are poorly visible. The RF-based navigation system is designed to comprise one transmitter, one receiver and several antennas in order to enable coarse-mode inter-satellite distance estimation (meter level) based on pseudorange measurements and fine-mode distance (centimeter level) and line-of-sight (LOS) estimation (sub-degree level) based on carrier phases in addition to pseudorange. A benchmarking system, called the Formation Flying Radio Frequency (FFRF) sensor, has been successfully shown and demonstrated on PRISMA mission. This research improves the performance of FFRF with respect to the technologies 1) to deal with errors and uncertainties, especially multipath; 2) to perform an unaided, fast and reliable carrier phase integer ambiguity resolution (IAR); and 3) to share channels among multiple spacecraft. Multipath In space applications, receivers on space vehicles may suffer from very short- delay multipath (< 4 m), reflected from the vehicle itself or from other vehicles during the operations of rendezvous and docking. The thesis proposes a novel method, termed ""Multipath Envelope Curve Fitting"", to mitigate very-short-delay-multipath on pseudorange measurements by approximately 50%. It also exhibits a promising performance for medium or large delayed multipath as compared to state-of-the-art methods. The method is based on the fact that the signal strength information, reported by early or late correlators inside the receiver, has an in-phase correlation with the pseudorange multipath error. By linearly combining multiple signal strength estimators from multiple correlators, the pseudorange multipath error has been accurately estimated. The weights for the linear combination were obtained by curve fitting based on the least-squares adjustment. A simple implementation strategy was also proposed that enables a receiver-internal multipath estimation process operated in conjunction with the tracking loop with a minimal additional computational overhead. Compared to the pseudorange multipath, the carrier phase multipath has more significant impacts on high precision navigation, especially when it is coupled with the carrier phase IAR. By making use of the signal to noise ratio (SNR) data of multiple antennas, this thesis proposes a novel cascaded extended Kalman Filter (EKF) to mitigate carrier phase multipath. This method accelerates the IAR process significantly and guarantees an achievement of sub-degree LOS accuracy. Both real-valued and complex-valued EKF are proposed and evaluated. The complex-valued EKF has been found to be insensitive to poorly defined initial conditions, when the real-valued EKF has difficulties converging. Moreover, the complex-valued EKF has shown better convergence properties for SNR observations with a large amount of noise. Integer Ambiguity Resolution The second challenge of this research is to perform an unaided, fast and reliable carrier phase IAR. Single-epoch IAR algorithms are proposed in this thesis, by making use of a nonlinear quadratic LOS length constraint and taking advantages of antenna arrays. Two methods, namely, the validation method and the subset ambiguity bounding method, are proposed. They replace the equality quadratic constraint by inequality boundaries such that the well known Least-squares AMBiguity Decorrelation Adjustment (LAMBDA) integer ambiguity resolution process is implemented within a pre-defined threshold to increase the integer search fidelity. Numerical simulations and field tests demonstrated that both the validation method and the subset ambiguity bounding method provided remarkable improvements with up to 80% higher success rates than the original LAMBDA method based on single-epoch measurements. The validation method showed a slightly better performance than the subset ambiguity bounding method as they differ in utilizing all-ambiguity-set and subset-ambiguity, respectively. Better IAR robustness against multipath can also be observed as compared to the original LAMBDA method. An Ambiguity Dilution of Precision (ADOP) measure under the LOS constraint is derived, which is an easy-to-use and insightful indicator of the ambiguity resolution capability. A rule-of-thumb for the pre-defined threshold has also been derived in the closed-form expression, providing guidance on how to choose boundaries according to the noise level and antenna geometry. Multiple Access Technology Enabling multiple access capability is of critical importance for future missions with four or more spacecraft. The Code Division Multiple Access (CDMA) technology is recommended to be used in combination with a flexible role rotating topology in this research. This allows coping with time-critical relative navigation requirements and enables flexible operations during various mission phases. Through realistic formation case studies, the limitation of CDMA was extensively investigated in terms of the multiple access interference (MAI) which could result in a ranging error of several meters and is highly dependent on the Doppler offset. Recommendations are given in this thesis to reduce corresponding MAI errors.","relative navigation; GNSS; formation flying; multipath; integer ambiguity resolution","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Space System Engineering","","","",""
"uuid:262db522-1a14-454f-a933-47f3e96376fb","http://resolver.tudelft.nl/uuid:262db522-1a14-454f-a933-47f3e96376fb","Plasma nitriding induced growth of Pt-nanowire arrays as high performance electrocatalysts for fuel cells","Du, S.; Lin, K.; Malladi, S.R.K.; Lu, Y.; Sun, S.; Xu, Q.; Steinberger-Wilckens, R.; Dong, H.","","2014","In this work, we demonstrate an innovative approach, combing a novel active screen plasma (ASP) technique with green chemical synthesis, for a direct fabrication of uniform Pt nanowire arrays on large-area supports. The ASP treatment enables in-situ N-doping and surface modification to the support surface, significantly promoting the uniform growth of tiny Pt nuclei which directs the growth of ultrathin single-crystal Pt nanowire (2.5-3 nm in diameter) arrays, forming a three-dimensional (3D) nano-architecture. Pt nanowire arrays in-situ grown on the large-area gas diffusion layer (GDL) (5 cm(2)) can be directly used as the catalyst electrode in fuel cells. The unique design brings in an extremely thin electrocatalyst layer, facilitating the charge transfer and mass transfer properties, leading to over two times higher power density than the conventional Pt nanoparticle catalyst electrode in real fuel cell environment. Due to the similar challenges faced with other nanostructures and the high availability of ASP for other material surfaces, this work will provide valuable insights and guidance towards the development of other new nano-architectures for various practical applications.","","en","journal article","Nature Publishing Group","","","","","","","","Applied Sciences","QN/Quantum Nanoscience","","","",""
"uuid:04a1ddb6-f1b3-4342-b297-5edf8aa0ddd1","http://resolver.tudelft.nl/uuid:04a1ddb6-f1b3-4342-b297-5edf8aa0ddd1","Updated Delft mass transport model DMT-2: Computation and validation","Hashemifarahani, H.; Ditmar, P.G.; Inacio, P.M.G.; Klees, R.; Guo, J.; Guo, X.; Liu, X.; Zhao, Q.; Didova, O.; Ran, J.; Sun, Y.; Tangdamrongsub, N.; Gunter, B.C.; Riva, R.E.M.; Steele-Dunne, S.C.","","2014","","","en","conference paper","EGU","","","","","","","","Civil Engineering and Geosciences","Geoscience & Remote Sensing","","","",""
"uuid:6e1a39dd-1581-4d87-b623-97d1dc39fb78","http://resolver.tudelft.nl/uuid:6e1a39dd-1581-4d87-b623-97d1dc39fb78","Micro Ramps in Supersonic Turbulent Boundary Layers: An experimental and numerical study","Sun, Z.","Scarano, F. (promotor)","2014","The micro vortex generator (MVG) is used extensively in low speed aerodynamic problems and is now extended into the supersonic flow regime to solve undesired flow features that are associated with shock wave boundary layer interactions (SWBLI) such as flow separation and associated unsteadiness of the interaction system. Numerous experimental and numerical studies have shown that despite their small size, such devices can alter the boundary layer properties very efficiently, when compared to the conventional vortex generators. In order to assist a more efficient design of MVGs, fundamental studies have been carried out to understand the associated wake properties such as the increased boundary layer mixing and the structure and stability of the induced vortex system. The present work is conducted in the framework of such fundamental studies. The micro ramp is among the most commonly used MVG devices and has been selected for the present investigations. The research is based both on wind tunnel experiments and numerical simulations in order to build a more comprehensive and detailed understanding of the flow behind a micro ramp immersed in a supersonic turbulent boundary layer. The choice of the experimental approach is justified by the fact that the incoming turbulent boundary layer exhibits a high Reynolds number (Re?=13,600), which makes it too challenging for extensive CFD investigation by using LES or DNS approaches. Variants of the micro ramp configuration as well as the attendant SWBLI can be studied efficiently by wind tunnel experiments adopting PIV as velocity field diagnostics. The use of numerical simulations by the implicit large eddy simulation (ILES) technique for one specific case enables the detailed inspection of the flow field that adds to the understanding of the flow development in regions or aspects where the experimental method provides limited access. Finally, there is general interest to know that till what extent numerical simulations can correctly identify the governing mechanisms of the boundary layer flow manipulation by micro ramps. Tomographic PIV is used as three-dimensional flow diagnostic technique in the investigation of flow organization in the micro ramp near wake (x/h?9~15). From the experimental data it is observed that the mean flow features a conical wake containing a pair of steady vortices aligned in streamwise direction. This is considered to be the basic mechanism of the boundary layer flow manipulation, whereas the wall-normal velocity component features a central focussed upwash with downwash motions at the sides. Simultaneously, a deficit region of streamwise velocity is produced in the center of the wake. The shear layer surrounding the wake is subject to Kelvin-Helmholtz (K-H) type instability and the instantaneous flow organization exhibits the formation of coherent K-H vortices that are arc shaped and dominate the velocity field fluctuations across the shear layer. Conditional averaging of the 3D velocity field yields the salient features of the interaction between the streamwise vortices and the K-H vortices whereas the former are found to be weakened at the generated of K-H vortices. The downstream decay of the flow features that are introduced by the micro ramp is relevant to its positioning with respect to the point of interaction between shock wave and boundary layer, indicating the relevance of investigating the further downstream development. Therefore experiments are conducted with large format PIV camera to study the decay in the center plane of the micro ramp far wake (x/h?12~32). In order to find a proper scaling parameter of the micro ramp wake, two geometrically similar micro ramps with different sizes are employed. Both streamwise and wall-normal velocity components exhibit a power-law decay in agreement with theories for the fully developed turbulent flow regime. The wall-normal velocity decays faster, approximately at a rate 2.5 times of the momentum deficit. The self-similarity of the velocity profiles is also examined. The streamwise velocity exhibits a good degree of self-similarity in the upper and lower shear layer, while the wall-normal component has overlapped upwash profiles. Concerning the turbulent properties, a strong anisotropy of velocity fluctuations is observed at upstream locations (x/h<20), nonetheless both fluctuation components decay to a similar magnitude when approaching the downstream end of the measurement domain (x/h>20). The organization of instantaneous vortical field is also investigated in the attempt to better understand their effect on the wake decay. Spatial auto-correlation of the instantaneous velocity fields yields the streamwise evolution of the average distance between vortices. Vortex pairing is identified in the range x/h=18~22 through an increase of such distance. The detection of counter-rotating vortices in the lower part of the wake suggests that the K-H vortices produced in the upper region of the shear layer propagate into the region close to the wall after vortex pairing, which eventually gives rise to ring-vortex formation in the later stage of the wake. A numerical study using ILES with high order scheme is carried out in collaboration with the University of Texas at Arlington. In order to establish a fair comparison with the experimental data, the flow conditions are made as similar as possible, matching the free stream Mach number and the ratio between micro ramp height and boundary layer thickness. The attendant limitations on computational resources limit the Reynolds number based on boundary layer momentum thickness to about one-third of that in the experiments. The comparison covers the most relevant quantities, such as the streamwise and wall-normal velocity and the peak vorticity. An overall good agreement is observed. A noticeable discrepancy involves underestimation of upwash motion: the wall-normal velocity amounts to 70% of the measured data. In the observation of instantaneous flow, vortex pairing is also identified and the spatial-temporal evolution of the K-H vortex is studied by tracking, which confirms the flow model conjectured from the planar PIV study in the center plane.","turbulence; flow control; Particle Image Velocimetry; Large Eddy Simulation; supersonic flow","en","doctoral thesis","","","","","","","","","Aerospace Engineering","Aerodynamics Wind Energy and Propulsion","","","",""
"uuid:43e4bd40-b647-4e90-b88e-1db0d9c64c8e","http://resolver.tudelft.nl/uuid:43e4bd40-b647-4e90-b88e-1db0d9c64c8e","Tunable bandpass filter with two adjustable transmission poles and compensable coupling","Luo, X. (TU Delft Electronics); Sun, S (External organisation); Staszewski, R.B. (TU Delft Electronics)","","2014","","","en","journal article","","","","","","Harvest","","","","","Electronics","","",""
"uuid:f7c83a60-8922-4e6d-860d-0bdcb10e3a6b","http://resolver.tudelft.nl/uuid:f7c83a60-8922-4e6d-860d-0bdcb10e3a6b","Macroscopic travel time reliability diagrams for freeway networks","Tu, H.; Li, H.; Van Lint, J.W.C.; Knoop, V.L.; Sun, L.","","2013","Travel time reliability is considered to be one of the key indicators of transport system performance. Knowledge of the mechanisms of travel time unreliability enables the derivation of explanatory models with which travel time reliability can be predicted and utilized in traffic management. Inspired by the macroscopic fundamental diagram (MFD), describing the relationship between production (average flow completing the trips) and vehicle accumulation (average density) in a traffic network, this paper investigates a macroscopic travel time reliability diagram (MRD) relating the travel time reliability to the network accumulation. The MFD relationship has potential because it characterizes the state of an entire traffic network with just two (production and accumulation) or three (adding spatial variability of accumulation) state variables. Likewise, the MRD describes the network travel time reliability as a function of just one independent state variable (network accumulation). Empirical analyses were performed to investigate the variability in MFD as seen in scatters and to show the travel time reliability in relation to the network accumulations. Traffic data from Dutch freeway networks were employed to facilitate the analyses. With the MRD for different freeway networks, it was found that a critical travel time reliability accumulation existed, below which network accumulation had little or no impact on travel time reliability and above which it had a significant impact. Also, the critical travel time reliability accumulation was, in general, lower than the critical MFD accumulation. These findings provide insights for road authorities in how to make trade-offs in traffic management between maximum production and travel time reliability.","","en","conference paper","Transportation Research Board","","","","","","","","Civil Engineering and Geosciences","Transport and Planning","","","",""
"uuid:5e25dcd3-0e23-448b-a606-cc5f7373a023","http://resolver.tudelft.nl/uuid:5e25dcd3-0e23-448b-a606-cc5f7373a023","Decay of the turbulent wake from the supersonic micro-ramp","Sun, Z.; Van Oudheusden, B.W.; Schrijer, F.F.J.; Scarano, F.","","2013","The wake resulting from two micro ramps operating in a supersonic boundary layer at Ma = 2:0 is investigated by means of PIV. Two micro ramps are investigated with height of 60% and 80% of the undisturbed boundary layer with thickness of 5.2 mm. The measurement domain encompasses the range from 10 to 32 ramp heights downstream of the device. The decay properties are evaluated in terms of time-averaged and root-mean-square (RMS) statistics. In the time-averaged flow field, the recovery of the imparted momentum deficit and the decay of upwash motion are revealed. The RMS fluctuations of the velocity components exhibit strong anisotropy at upstream locations but develop into a more isotropic regime downstream. The Kelvin-Helmholtz (K-H) instability at the upper shear layer further develops with the onset of vortex pairing. The wavelength evolution is estimated using statistic-based spatial auto-correlation. A marked transition with the wavelength nearly doubled is observed across the pairing regime.","","en","conference paper","PPrime","","","","","","","","Aerospace Engineering","Aerodynamics, Wind Energy & Propulsion","","","",""
"uuid:eb4a5871-728b-4da8-9fa9-706af7585cc2","http://resolver.tudelft.nl/uuid:eb4a5871-728b-4da8-9fa9-706af7585cc2","A Hybrid Sensor Based Backstepping Control Approach with its Application to Fault-Tolerant Flight Control","Sun, L.G.; De Visser, C.C.; Chu, Q.P.; Falkena, W.","","2013","Recently, an incremental type sensor based backstepping (SBB) control approach, based on singular perturbation theory and Tikhonov’s theorem, has been proposed. This Lyapunov function based method uses measurements of control variables and less model knowledge, and it is not susceptible to the model uncertainty caused by fault scenarios. In this paper, the SBB method has been implemented on a fixed wing aircraft with its focus on handling structural changes caused by damages. A new hybrid autopilot flight controller has been developed for a Boeing 747-200 aircraft after combining nonlinear dynamic inversion (NDI) with SBB control approach. Two benchmarks for fault tolerant flight control (FTFC), named rudder runaway and engine separation, are employed to evaluate the proposed method. The simulation results show that the proposed control approach leads to a zero tracking-error performance in nominal condition and guarantees the stability of the closed-loop system under failures as long as the reference commands are located in the safe flight envelope.","fault tolerant control; backstepping control; aircraft safety; flight control","en","journal article","AIAA","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:3531544a-6750-4575-b8b8-6138a662472f","http://resolver.tudelft.nl/uuid:3531544a-6750-4575-b8b8-6138a662472f","Differences in abdominal force between conventional and single port laparoscopy","Sun, S.; Dankelman, J.; Horeman, T.","","2013","In laparoendoscopic single-site surgery (LESS), only one single incision is used to introduce all instruments into the abdominal cavity. The introduction of multi-channel single-port devices enabled insertion of laparoscopic instruments and laparoscope through one single entry point instead of multiple entry points in conventional laparoscopic surgery (CLS). From recent studies is known that the distance between instruments influences the force exerted on tissue during manipulation. To investigate whether this force difference can also be found on the abdominal wall, a two-dimensional force measurement mechanism was designed and incorporated in a standard trainer box. The sensors were used to measure the abdominal force exerted by either the standard trocar or the single-port device on the artificial skin that mimics the abdominal wall. A randomized crossover study consisted of 16 students and three experienced surgeons was conducted. The subjects were asked to perform a task with two different instrument configurations (CLS and LESS) in randomized order. The results showed that when performing a force-related task with LESS configuration, the maximum abdominal force was significantly higher compared with the conventional twoport CLS configuration.","","en","conference paper","","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:2f81cd45-0de3-4586-acac-02e7ca015692","http://resolver.tudelft.nl/uuid:2f81cd45-0de3-4586-acac-02e7ca015692","Precise and faster GNSS signal direction of arrival estimation","Sun, R.; O'Keefe, K.; Guo, J.; Gill, E.","","2013","This paper proposes a precise and fast direction of arrival estimation method using Global Navigation Satellite System (GNSS) carrier phase measurements. Single-epoch, single-satellite integer cycle ambiguities are reliably resolved by making use of constraints and taking advantages of antenna arrays. The algorithm shows good robustness in cases where signal interruption or corruption occurs on some antenna elements as long as four antenna elements in a non-planar array have uncorrupted observables. The algorithm is demonstrated by field tests where antenna elements are connected to multiple receivers with an external common clock. The results indicate a high success rate of single-epoch ambiguity resolution and high direction of arrival accuracy.","signal direction of arrival; ambiguity resolution; constraint; antenna array","en","journal article","Cambridge University Press","","","","","","","2014-08-01","Aerospace Engineering","Space Engineering","","","",""
"uuid:fa68d1b6-6236-49b8-819f-c76452ddab3b","http://resolver.tudelft.nl/uuid:fa68d1b6-6236-49b8-819f-c76452ddab3b","Online Aerodynamic Model Identification using a Recursive Sequential Method for Multivariate Splines","Sun, L.G.; De Visser, C.C.; Chu, Q.P.; Mulder, J.A.","","2013","Avoiding high computational loads is essential to online aerodynamic model identi- fication algorithms, which are at the heart of any model-based adaptive flight control system. Multivariate simplex B-spline (MVSB) methods are excellent function approximation tools for modeling the nonlinear aerodynamics of high performance aircraft. However, the computational efficiency of the MVSB method must be improved in order to enable real-time onboard applications, for example in adaptive nonlinear flight control systems. In this paper, a new recursive sequential identification strategy is proposed for the MVSB method aimed at increasing its computational efficiency, thereby allowing its use in onboard system identification applications. The main contribution of this new method is a significant reduction of computational load for large scale online identification problems as compared to the existing MVSB methods. The proposed method consists of two sequential steps for each time interval, and makes use of a decomposition of the global problem domain into a number of subdomains, called modules. In the first step the B-coefficients for each module are estimated using a least squares estimator. In the second step the local B-coefficients for each module are then smoothened into a single global B-coefficient vector using a linear minimum mean square errors (LMMSE) estimation. The new method is compared to existing batch and recursive MVSB methods in a numerical experiment in which an aerodynamic model is recursively identified based on data from an NASA F-16 wind-tunnel model.","recursive identification; aerodynamic model identification; multivariate splines","en","journal article","AIAA","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:e070de9d-e805-4aa5-9bcc-7f8719bb56e1","http://resolver.tudelft.nl/uuid:e070de9d-e805-4aa5-9bcc-7f8719bb56e1","A novel adaptive kernel method with kernel centers determined by a support vector regression approach","Sun, L.G.; De Visser, C.C.; Chu, Q.P.; Mulder, J.A.","","2012","The optimality of the kernel number and kernel centers plays a significant role in determining the approximation power of nearly all kernel methods. However, the process of choosing optimal kernels is always formulated as a global optimization task, which is hard to accomplish. Recently, an algorithm, namely improved recursive reduced least squares support vector regression (IRR-LSSVR), was proposed for establishing a global nonparametric offline model, which demonstrates significant advantage in choosing representing and fewer support vectors compared with others. Inspired by the IRR- LSSVR, a new adaptive parametric kernel method called WV-LSSVR is proposed in this paper using the same type of kernels and the same centers as those used in the IRR-LSSVR. Furthermore, inspired by the multikernel semiparametric support vector regression, the effect of the kernel extension is investigated in a recursive regression framework, and a recursive kernel method called GPK-LSSVR is proposed using a compound type of kernels which are recommended for Gaussian process regression. Numerical experiments on benchmark data sets confirm the validity and effectiveness of the presented algorithms. The WV-LSSVR algorithm shows higher approximation accuracy than the recursive parametric kernel method using the centers calculated by the k-means clustering approach. The extended recursive kernel method (i.e. GPK-LSSVR) has not shown advantage in terms of global approximation accuracy when validating the test data set without real-time updation, but it can increase modeling accuracy if the real-time identification is involved.","support vector machine; recursive identification; adaptive model; kernel basis function","en","journal article","Elsevier","","","","","","","","Aerospace Engineering","Control & Operations","","","",""
"uuid:6bd4b059-b6fb-4b3c-8972-f39bfbedd791","http://resolver.tudelft.nl/uuid:6bd4b059-b6fb-4b3c-8972-f39bfbedd791","The minimum wind speed for sustainable turbulence in the nocturnal boundary layer","Van de Wiel, B.J.H.; Moene, A.F.; Jonker, H.J.J.; Baas, P.; Basu, S.; Donda, J.M.M.; Sun, J.; Holtslag, A.A.M.","","2012","The collapse of turbulence in the nocturnal boundary layer is studied by means of a simple bulk model that describes the basic physical interactions in the surface energy balance. It is shown that for a given mechanical forcing, the amount of turbulent heat that can be transported downward is limited to a certain maximum. In the case of weak winds and clear skies, this maximum can be significantly smaller than the net radiative loss minus soil heat transport. In the case when the surface has low heat capacity, this imbalance generates rapid surface cooling that further suppresses the turbulent heat transport, so that eventually turbulence largely ceases (positive feedback mechanism). The model predicts the minimum wind speed for sustainable turbulence for the so-called crossing level. At this level, some decameters above the surface, the wind is relatively stationary compared to lower and higher levels. The critical speed is predicted in the range of about 5–7 m s21, depending on radiative forcing and surface properties, and is in agreement with observations at Cabauw. The critical value appears not very sensitive to model details or to the exact values of the input parameters. Finally, results are interpreted in terms of external forcings, such as geostrophic wind. As it is generally larger than the speed at crossing height, a 5 m s21 geostrophic wind may be considered as the typical limit below which sustainable, continuous turbulence under clear-sky conditions is unlikely to exist. Below this threshold emergence of the very stable nocturnal boundary layer is anticipated.","surface layer; wind; surface observations; land surface model; nonlinear models; single column models","en","journal article","American Meteorological Society","","","","","","","2013-05-01","Applied Sciences","Multi-Scale Physics","","","",""
"uuid:0f15a445-9e2d-4468-afcc-08a1d8a09c55","http://resolver.tudelft.nl/uuid:0f15a445-9e2d-4468-afcc-08a1d8a09c55","Potentials and Limitations of CDMA Networks for Combined Inter-Satellite Communication and Relative Navigation","Sun, R.; Guo, J.; Gill, E.K.A.; Maessen, D.C.","","2012","Precision formation flying missions require formation acquisition and maintenance through the interactions among spacecraft by the inter-satellite communication and relative navigation. This paper analyses the dedicated system constraints of the network architecture for precision formation flying missions. The critical time issue and the operational flexibility are found to be two main constraints. Potentially applicable architectures are discussed and evaluated, which combine different multiple access technologies, half-duplex/full-duplex configurations and network topologies. It is proven that the most suitable and efficient architecture for PFF mission is the use of the halfduplex CDMA with the topology that allows the role of being reference rotating from one spacecraft to another in different time slots. The capability of CDMA is also investigated in terms of the multiple access interference. The paper verifies that this interference can limit the maximum number of spacecraft and bounds the inter-satellite range diversity. The interference exhibits a Doppler dependency and suffers as well from the near-far problem. Inter-satellite navigation accuracy will easily drop down below meter level at the moments of zero- or n-kHz Doppler crossovers, and also in case of the signals being corrupted by the near-by interferences. Two realistic mission scenarios are provided to verify the severe effects of the interference. Operational considerations and interference mitigation methods are also recommended.","precision formation flying; communication; relative navigation; CDMA; multiple access interference","en","journal article","IARIA","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:3d86ae9e-5822-4721-94ed-8ba02ca1e27b","http://resolver.tudelft.nl/uuid:3d86ae9e-5822-4721-94ed-8ba02ca1e27b","Measurements of Quasiparticle Tunneling Dynamics in a Band-Gap-Engineered Transmon Qubit","Sun, L.; Di Carlo, L.; Reed, M.D.; Catelani, G.; Bishop, L.S.; Schuster, D.I.; Johnson, B.R.; Yang, G.A.; Frunzio, L.; Glazman, L.; Devoret, M.H.; Schoelkopf, R.J.","","2012","We have engineered the band gap profile of transmon qubits by combining oxygen-doped Al for tunnel junction electrodes and clean Al as quasiparticle traps to investigate energy relaxation due to quasiparticle tunneling. The relaxation time T1 of the qubits is shown to be insensitive to this band gap engineering. Operating at relatively low-EJ/EC makes the transmon transition frequency distinctly dependent on the charge parity, allowing us to detect the quasiparticles tunneling across the qubit junction. Quasiparticle kinetics have been studied by monitoring the frequency switching due to even-odd parity change in real time. It shows the switching time is faster than 10???s, indicating quasiparticle-induced relaxation has to be reduced to achieve T1 much longer than 100???s.","","en","journal article","American Physical Society","","","","","","","","Applied Sciences","QN/Quantum Nanoscience","","","",""
"uuid:97743381-042e-4495-ad7c-bee12068ff3d","http://resolver.tudelft.nl/uuid:97743381-042e-4495-ad7c-bee12068ff3d","Recycling of Aluminum from Fibre Metal Laminates","Zhu, G.; Xiao, Y.; Yang, Y.; Wang, J.; Sun, B.; Boom, R.","","2012","Recycling of aluminum alloy scrap obtained from delaminated fibre metal laminates (FMLs) was studied through high temperature refining in the presence of a salt flux. The aluminum alloy scrap contains approximately mass fraction w(Cu) = 4.4%, w(Mg) = 1.1% and w(Mn) = 0.6% (2024 aluminum alloy). The main objective of this research is to obtain a high metal yield, while maintaining its original alloy compositions. The work focuses on the metal yield and quality of recycled Al alloy under different refining conditions. The NaCl-KCl salt system was selected as the major components of flux in the Al alloy recycling. Two different flux compositions were employed at NaCl to KCl mass ratios of 44:56 and 70:30 respectively, based on either the eutectic composition, or the European preference. Different additives were introduced into the NaCl-KCl system to study the effect of flux component on recycling result. Although burning and oxidation loss of the alloying elements during re-melting and refining take place as the drawbacks of conventional refining process, the problems can be solved to a large extent by using an appropriate salt flux. Experimental results indicate that Mg in the alloy gets lost when adding cryolite in the NaCl-KCl salt system, though the metal yield can reach as high as 98%. However, by adding w(MgF2) = 5% into the NaCl-KCl salt system (instead of using cryolite) all alloying elements were well controlled to its original composition with a metal yield of almost 98%.","Al-Cu-Mg alloy, 2024 Al, recycling, cryolite, salt flux","en","journal article","Springer-Verlag","","","","","","","","Mechanical, Maritime and Materials Engineering","Materials Science and Engineering","","","",""
"uuid:670a4d48-1736-409a-9847-8c077fa29bf8","http://resolver.tudelft.nl/uuid:670a4d48-1736-409a-9847-8c077fa29bf8","Degradation Behavior of Epoxy Resins in Fibre Metal Laminates Under Thermal Conditions","Zhu, G.; Xiao, Y.; Yang, Y.; Wang, J.; Sun, B.; Boom, R.","","2012","GLARE (glass fibre/epoxy reinforced aluminum laminate) is a member of the fiber metal laminate (FML) family, and is built up of alternating metal and fiber layers. About 500m2 GLARE is employed in each Airbus A380 because of the superior mechanical properties over the monolithic aluminum alloys, such as weight reduction, improved damage tolerance and higher ultimate tensile strength. Many tons of new GLARE scraps have been accumulated during the Airbus A380 manufacturing. Moreover, with the increasing plane orders of Airbus A380, more and more end-of-life (EOL) GLARE scrap will be generated after retire of planes within forty years. Thermal processing is a potential method for the material recycling and re-use from GLARE with the aim of environmental protection and economic benefits. The current study indicatdes that thermal delamination is a crucial pre-treatment step for the GLARE recycling. The decomposition behavior of the epoxy resins at elevated temperatures was investigated by using the simultaneous thermal analysis, thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). Based on the thermal analysis results, GLARE thermal delamination experiments at refined temperatures were carried out to optimize the treatment temperature and holding time.","fibre metal laminates, GLARE (glass fibre/epoxy reinforced aluminum laminate), recycling, decomposition kinetics, thermal degradation","en","journal article","Springer-Verlag","","","","","","","","Mechanical, Maritime and Materials Engineering","Materials Science and Engineering","","","",""
"uuid:bbd816bb-3f8c-4e5e-b956-7ab9eee328f3","http://resolver.tudelft.nl/uuid:bbd816bb-3f8c-4e5e-b956-7ab9eee328f3","The three-dimensional flow organization past a micro-ramp in a supersonic boundary layer","Sun, Z.; Schrijer, F.F.J.; Scarano, F.; Van Oudheusden, B.W.","","2012","The three-dimensional instantaneous flow organization in the near wake of a micro-ramp interacting with a Mach 2.0 supersonic turbulent boundary layer is studied using tomographic particle image velocimetry. The mean flow reveals a wake with approximately circular cross section dominated by a pair of counter-rotating streamwise vortices generating a focused upwash motion at the symmetry plane. In the instantaneous flow organization a flow instability of Kelvin-Helmholtz (K-H) type is observed in the shear layer between the wake and outer flow. Intermittent arc-shaped vortices are visualized that locally accelerate the outer fluid and further decelerate the inner region. The streamwise vortex pair displays an undulating behavior. Their interaction with the K-H vortices considerably increases the overall complexity of the wake. It appears that the streamwise vortex filaments under the K-H vortex train approach each other due to the focused ejection activity resulting from the K-H vortex. The statistical properties of turbulent fluctuations yield maximum activity at the core of the streamwise vortex and within the upwash region, and the Reynolds stresses peak within the shear layer. The topological organization of the wake vortices is formulated through a conditional average over the vorticity field.","boundary layer turbulence; external flows; flow visualisation; fluctuations; Kelvin-Helmholtz instability; shear turbulence; statistical analysis; supersonic flow; vortices; wakes","en","journal article","American Institute of Physics","","","","","","","","Aerospace Engineering","Aerodynamics & Wind Energy","","","",""
"uuid:b60258cb-4a60-4611-a496-60476bfc76ef","http://resolver.tudelft.nl/uuid:b60258cb-4a60-4611-a496-60476bfc76ef","Travel time reliability during evacuation: The impact of heterogeneous driving behavior","Tu, H.; Pel, A.J.; Li, H.; Sun, L.","","2012","Earlier studies have shown that driving behavior differs strongly in emergency conditions compared with behavior in normal traffic conditions. In this paper, these findings are followed up with an investigation of how these differences in driving behavior affect travel time reliability. In particular, the focus is on the effect of relatively strong heterogeneity in driving behavior. The microscopic simulation framework S-PARAMICS is adapted accordingly and applied to the emergency evacuation network of the Dutch city of Almere. This experimental setup allows a structured and in-depth analysis of the relationship between a number of driving behavior parameters and the emergent travel time reliability. The main findings from this study are thus insightful and directly applicable to evacuation planning and management studies. For instance, it is found that although a reduction in drivers’ mean time headway and minimum gap acceptance typically improves the overall evacuation time, travel times are simultaneously less reliable. Also, the reliability of travel times decreases over time and results in much less reliable travel times for those travelers who depart later. And finally, in general, heterogeneity in driving behavior strongly reduces travel time reliability.","transportation","en","journal article","Transportation Research Board of the National Academies","","","","","","","","Civil Engineering and Geosciences","Transport & Planning","","","",""
"uuid:1a7741c0-5bd0-4e77-a679-cb77c9307c11","http://resolver.tudelft.nl/uuid:1a7741c0-5bd0-4e77-a679-cb77c9307c11","Ultraviolet-vacuum ultraviolet photoluminescence and x ray radioluminescence of Ce3+-doped Ba3MgSi2O8","Ding, X.; Liang, H.; Hou, D.; Su, Q.; Dorenbos, P.; Sun, S.; Tao, Y.","","2011","Ce3+-doped Ba3MgSi2O8 phosphors were prepared by a solid-state reaction route. The photoluminescence properties in the vacuum ultraviolet-vis spectral range and the x ray excited radioluminescence were investigated. Ce3+ ions were found to enter three different sites in the host lattice. Five excitation bands and two emission bands of Ce(1)3+ centers were observed in the spectra. For Ce(2)3+ and Ce(3)3+ centers, the lowest 5d excitation bands and the emission bands were determined. The light yields of samples under x ray excitation were estimated by comparing the integrated emission intensities of our samples with that of BaF2.","barium compounds; cerium; colour centres; magnesium compounds; phosphors; photoluminescence","en","journal article","American Institute of Physics","","","","","","","","Applied Sciences","RRR/Radiation, Radionuclides and Reactors","","","",""
"uuid:97b8c96c-a9c9-4687-afd0-16c601b08ccc","http://resolver.tudelft.nl/uuid:97b8c96c-a9c9-4687-afd0-16c601b08ccc","Computational identification of insertional mutagenesis targets for cancer gene discovery","De Jong, J.; De Ridder, J.; Van der Weyden, L.; Sun, N.; Van Uitert, M.; Berns, A.; Van Lohuizen, M.; Jonkers, J.; Adams, D.J.; Wessels, L.F.A.","","2011","Insertional mutagenesis is a potent forward genetic screening technique used to identify candidate cancer genes in mouse model systems. An important, yet unresolved issue in the analysis of these screens, is the identification of the genes affected by the insertions. To address this, we developed Kernel Convolved Rule Based Mapping (KC-RBM). KC-RBM exploits distance, orientation and insertion density across tumors to automatically map integration sites to target genes. We perform the first genome-wide evaluation of the association of insertion occurrences with aberrant gene expression of the predicted targets in both retroviral and transposon data sets. We demonstrate the efficiency of KC-RBM by showing its superior performance over existing approaches in recovering true positives from a list of independently, manually curated cancer genes. The results of this work will significantly enhance the accuracy and speed of cancer gene discovery in forward genetic screens. KC-RBM is available as R-package.","","en","journal article","Oxford University Press","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Mediamatics","","","",""
"uuid:d061e0c8-99cd-419e-be44-225fe063f84c","http://resolver.tudelft.nl/uuid:d061e0c8-99cd-419e-be44-225fe063f84c","Characterizing Network Architecture for Inter-satellite Communication and Relative Navigation in Precise Formation Flying","Sun, R.; Guo, J.; Gill, E.K.A.; Maessen, D.","","2011","Precise formation flying (PFF) missions require formation acquisition and maintenance through interactions among spacecraft by inter-satellite communication and relative navigation. That requires the network architecture to satisfy dedicated system constraints of time-criticality for updating navigation measurements and flexibility for implementation across various phases of mission operations. Potentially applicable architectures that combine different multiple access technologies, half-duplex/full duplex configurations, and network topologies are discussed and evaluated. Half-duplex CDMA with roles rotating among all spacecraft is shown more suitable and efficient for PFF missions. Its limitation in terms of multiple access interference is analyzed as well.","precise formation flying; communication; relative navigation; time-critical; various mission phases; CDMA","en","conference paper","IARIA","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:9594254e-547a-439e-a609-f6d0e6c1e2a8","http://resolver.tudelft.nl/uuid:9594254e-547a-439e-a609-f6d0e6c1e2a8","Opportunities and challenges of wireless sensor networks in space","Sun, R.; Guo, J.; Gill, E.K.A.","","2010","Challenges and opportunities of wireless sensor networks (WSNs) in space applications are presented. The investigation of internet protocols, ad hoc routing and commercial-off-the-shelf (COTS) wireless communication protocols for efficient and reliable network design is addressed. In order to facilitate the analysis, several application scenarios of space-based WSNs are given, including autonomous formation flying, very-small-satellite cluster/swarm, fractionated spacecraft, onboard sensor network and surface vehicles for planetary exploration. Criteria that contain network scale, link range, degree of dynamics, data rate, power consumption, time intensive requirement, and degree of cooperation are proposed in order to classify applications and choose the most potentially applicable technologies. Different levels of challenges to implement each application are also compared.","","en","conference paper","International Astronautical Federation","","","","","","","","Aerospace Engineering","Space Engineering","","","",""
"uuid:3de5fc36-dd99-4d59-972a-9b172a8c8b2e","http://resolver.tudelft.nl/uuid:3de5fc36-dd99-4d59-972a-9b172a8c8b2e","Monolithically Inegrated Silicon Bipolar RF Oscillators","Sun, Y.","Beats, R.G.F. (promotor)","1999","","Silicon bipolar RFIC; Microwave oscillators","en","doctoral thesis","","","","","","","","","Electrical Engineering, Mathematics and Computer Science","","","","",""
"uuid:b206042e-ab94-48fd-97ab-b87e1c924878","http://resolver.tudelft.nl/uuid:b206042e-ab94-48fd-97ab-b87e1c924878","Buckling problems of sandwich shells","Sun, B.H.","","1992","","","en","report","Delft University of Technology","","","","","","","","Aerospace Engineering","","","","",""