"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:dadafd2e-823d-453b-8542-a50af6923346","http://resolver.tudelft.nl/uuid:dadafd2e-823d-453b-8542-a50af6923346","Mimosa: Modular Self-folding Hinges Kit for Creating Shape-changing Objects","Liu, Q. (TU Delft Emerging Materials); Ghodrat, S. (TU Delft Emerging Materials); Jansen, K.M.B. (TU Delft Emerging Materials)","","2024","We developed a shape-changing constructive kit, named Mimosa1. A key component of the toolkit is the modular hinges, each of which is equipped with two antagonistic shape memory alloy (SMA) wires. One wire deforms the hinge to approach its predetermined angle at high temperature, and another wire drives the hinge back when it cools down. Hinge leaves are available in different materials including acrylic, cardboard and textile, which increases the versatility of the toolkit. Every hinge weighs 2.1-5.4 g, and generates up to 5.7 N actuation force. A Bluetooth control module was developed, enabling remote control of the shape-changing objects. Mimosa aims to inspire designers to explore and create interactive shape-morphing objects with SMAs. A few examples are given such as a gripper, a rolling robot, a butterfly, an airplane and a self-closing pocket. A workshop study with 6 participants showed that Mimosa indeed motivated and inspired the participants to create new ideas.","Crafting; Shape Memory Alloy; Shape-Changing Interfaces; Smart Hinge; Tangible User Interfaces; Toolkit","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Emerging Materials","","",""
"uuid:2b4273b0-0729-4473-af1e-5c2e87679ee3","http://resolver.tudelft.nl/uuid:2b4273b0-0729-4473-af1e-5c2e87679ee3","RAP pre-treatment for fast cold in-place recycling","Lin, P. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Ren, S. (TU Delft Pavement Engineering); Li, Yi (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering); Welvaarts, B. (De Jong Zuurmond); Brouns, K. (De Jong Zuurmond)","Zhang, Yuqing (editor); Airey, Gordon (editor); Rahman, Mujib (editor); Wang, Haopeng (editor)","2024","Developed by Delft University of Technology, the tri-component polyurethane modified cold binder (PMCB) displays impressive durability and strength in asphalt mixtures, showing promise as a reliable binder for cold in-place recycling. However, when applying PMCB for rapid, in-situ recycling, the presence of moisture in reclaimed asphalt pavement (RAP) poses a significant challenge. To address this, an innovative approach involving treatment of the wet RAP with Calcium dioxide (CaO) prior to the integration of PMCB was tested. Evaluation methods used included the Indirect Tensile Test (ITT), followed by the calculation of the Indirect Tensile Strength Ratio (ITSR) to assess moisture susceptibility. Furthermore, Cantabro tests were performed to determine the material loss under abrasion and weathering conditions. These assessments underscored the feasibility of this approach. The treatment of wet RAP with CaO has proven a viable strategy for rapid in-situ recycling with PMCB, contributing to sustainable pavement construction. In addition, the research identified that a 5.5% concentration of the PMCB binder maximizes structural integrity and performance in the considered RAP.","","en","conference paper","CRC Press / Balkema - Taylor & Francis Group","","","","","","","2024-06-01","","","Pavement Engineering","","",""
"uuid:7b386549-93d1-499f-97cc-a0f55f41405a","http://resolver.tudelft.nl/uuid:7b386549-93d1-499f-97cc-a0f55f41405a","Machine learning assisted early anomaly detection of LEDs with spectral power distribution modeling","Liu, Minne (Fudan University); Ibrahim, Mesfin S. (New Territories); Wen, Minzhen (Fudan University); Li, Sheng (Shanhai Yaming Lighting Co.Ltd); Wang, An (Shanhai Yaming Lighting Co.Ltd); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Fan, J. (TU Delft Electronic Components, Technology and Materials; Fudan University; Chinese Academy of Sciences; Fudan Zhangjiang Institute,)","","2023","Spectral power distribution (SPD) is the radiation power intensity at different wavelengths, containing the most basic photometric and colorimetric performance of the illuminant, which is able to predict the lifetime of LEDs. This paper proposes an SPD model assisted by machine learning algorithms to detect the early failure of white LEDs. The SPD features of 3W high-power white LEDs were firstly extracted by the statistical models of Gaussian, Lorentz, and Asym2sig functions. An unsupervised learning method, principal component analysis (PCA), was then used to reduce the extracted features parameters’ dimensions. Next a K-nearest neighbor (KNN)-based method was used to detect LEDs’ anomalies by dividing the main cluster into groups, and estimating the distance from the center of mass of each cluster to the test point. The results showed the following: (1) for selected white LEDs, the Asym2sig function has a better fitting result than Gaussian and Lorentz functions; (2) machine learning methods can significantly assist in LED anomaly detection and can decrease the amount of anomaly detection time to 789.6 h, compared to the 1311 h when lumen maintenance degradation reaches 70% as required by IES TM21.","White LEDs; Spectral power distribution; Anomaly detection; Principal component analysis; K-nearest neighbor","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.","","2023-09-24","","","Electronic Components, Technology and Materials","","",""
"uuid:8f19f4d5-90f1-4fe7-847a-745bc35dfb28","http://resolver.tudelft.nl/uuid:8f19f4d5-90f1-4fe7-847a-745bc35dfb28","Study on Sintering Mechanism and Mechanical Properties of Nano-Cu based on Molecular Dynamics Simulation","Qian, Cheng (Fudan University); Hu, D. (TU Delft Electronic Components, Technology and Materials); Liu, Xu (Fudan University); Fan, Xuejun (Lamar University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials; Fudan University); Fan, J. (TU Delft Electronic Components, Technology and Materials; Fudan University; Research Institute of Fudan University, Ningbo)","","2023","Nano-metal materials sintering has received increasing attention in recent years for its promising performance in the wide bandgap semiconductor packaging. In this paper, molecular dynamics (MD) simulation method were applied to simulate the nano-Cu sintering mechanism and the subsequent mechanical behavior. Hybrid sintering, comprising nanosphere (NS) and nanoflake (NF), was carried out at temperatures ranging from 500K to 650K. Furthermore, shearing simulations were conducted with constant strain rates on the sintered structure at multiple temperatures, and subsequently correlated the extracted mechanical properties with the sintering behavior. The results indicated that the mechanical properties of nano-Cu sintered structure were improved by tuning material composition and increasing the sintering temperature. We established a relationship between the sintered microstructure and mechanical response, the shear modulus and shear strength of the sintered structure with NF particles increased to 41.2GPa and 3.51GPa respectively. It offers valuable insights into the preparation phase of nano Cu paste for sintering technology.","Nano Cu sintering; molecular dynamics simulation; Nanoflake; Shearing simulation","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.","","2023-10-17","","","Electronic Components, Technology and Materials","","",""
"uuid:422b1ea4-f64e-421b-aacb-e85c819b2061","http://resolver.tudelft.nl/uuid:422b1ea4-f64e-421b-aacb-e85c819b2061","Plug and Power: Fingerprinting USB Powered Peripherals via Power Side-channel","Spolaor, Riccardo (Shandong University); Liu, Hao (Shandong University); Turrin, Federico (University of Padua); Conti, M. (TU Delft Cyber Security; University of Padua); Cheng, Xiuzhen (Shandong University)","","2023","The literature and the news regularly report cases of exploiting Universal Serial Bus (USB) devices as attack tools for malware injections and private data exfiltration. To protect against such attacks, security researchers proposed different solutions to verify the identity of a USB device via side-channel information (e.g., timing or electromagnetic emission). However, such solutions often make strong assumptions on the measurement (e.g., electromagnetic interference-free area around the device), on a device’s state (e.g., only at the boot or during specific actions), or are limited to one particular type of USB device (e.g., flash drive or input devices).In this paper, we present PowerID, a novel method to fingerprint USB peripherals based on their power consumption. PowerID analyzes the power traces from a peripheral to infer its identity and properties. We evaluate the effectiveness of our method on an extensive power trace dataset collected from 82 USB peripherals, including 35 models and 8 types. Our experimental results show that PowerID accurately recognizes a peripheral type, model, activity, and identity.","USB Security; Power Side-Channel; USB peripherals; Hardware fingerprinting","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.","","2024-02-29","","","Cyber Security","","",""
"uuid:69e5da91-40a1-46d4-91a8-4ccf70779b26","http://resolver.tudelft.nl/uuid:69e5da91-40a1-46d4-91a8-4ccf70779b26","Navigating project management talent in the data-rich era","Papadonikolaki, E. (University College London (UCL)); Liu, Y. (TU Delft Integral Design & Management; Nanjing University); Maritshane, Kirk; Chan, P.W.C. (TU Delft Design & Construction Management)","","2023","The digital transformation in project management is causing disruption on how the organizations recognize and value the skills and expertise of the new data-savvy talents in organization’s decision-making processes for improved project delivery. Existing research on digital transformation in projects has mainly focused on what technologies can help organizations and people achieve, without connecting to the disruptions that technologies bring to projects human and social capital. To address this deficiency and harness the data-rich era, there is a need to go beyond the prevailing technical line of thought and think about people’s issues in project settings. Therefore, this research aims to examine talent management initiatives for project management professionals on how they can exploit the inherent advantages of the data-rich era and digital transformation to build an inclusive workplace. The study poses two research objectives, first to understand how project management professionals experience the trends of the data-rich era in the project environment and data-savvy talent (also in light of the changing demographics in the sector) and second to identify the opportunities and obstacles for managing project management talent to deliver projects in the data-rich era. To answer these questions, this paper uses semi-structured interviews from a purposive sample of 24 interviewees with diverse project management experience. The interviewees were recruited from three main categories of stakeholders from industry, academia, and professional institutions. The research through qualitative data analysis and abductive thinking first identifies an overemphasis on developing data-savvy talent in the expense of attracting or retaining it. Second, the study documents the existence of six clusters of opportunities and obstacles in delivering of projects through data savvy project management talent. Accordingly, the identified themes/clusters of connectivity, communication, information management, project delivery, disruption, and project work and wellbeing provide new directions for talent management practices such as attracting, developing and retaining data-savvy talent in the data-rich era.","Digitalization; digital technologies; talent management; project management; project professionals","en","conference paper","","","","","","","","","","","Integral Design & Management","","",""
"uuid:37ef1cde-31b3-49f8-8848-51a4da2a332b","http://resolver.tudelft.nl/uuid:37ef1cde-31b3-49f8-8848-51a4da2a332b","Enhancing Indoor-to-Outdoor mmWave Communication with Transparent Amplifying Intelligent Surface","Liu, Bin (Katholieke Universiteit Leuven); Wang, Q. (TU Delft Embedded Systems); Pollin, Sofie (Katholieke Universiteit Leuven)","","2023","This paper presents a novel transparent amplifying intelligent surface (TAIS) architecture for uplink enhancement in indoor-to-outdoor mmWave communications. The TAIS is an amplifier-based transmissive intelligent surface that can refract and amplify the incident signal, instead of only refracting it with adjustable phase shift by most passive reconfigurable intelligent surfaces (RIS). With advanced indium tin oxide film and printing technology, TAIS can be fabricated on the windows without any visual effects. This paper primarily focuses on exploiting the TAIS-based architecture to boost the uplink spectral efficiency (SE) in indoor-to-outdoor mmWave communications. By jointly optimizing the TAIS's phase shift matrix and transmit power of the user equipment, the uplink SE can be maximized by exploiting the nonlinearity in the TAIS's amplification process. The key point is that we drive the optimal phase shift matrix that maximizes the SE and deduces its closed-form representation. The SE maximization is then proved to be transferred to the transmit power optimization problem. Another important aspect is that we design a low-complexity algorithm to solve the problem using the difference of convex programming. Simulations show that our proposed TAIS can increase the SE by up to 32.6% as compared to its alternative methods.","Reconfigurable intelligent surface; transparent amplifying intelligent surface (TAIS); spectral efficiency; indoorto-outdoor communication; nonlinear amplification","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.","","2024-04-23","","","Embedded Systems","","",""
"uuid:fcd4097c-f797-42f4-84c8-da1472ccb75d","http://resolver.tudelft.nl/uuid:fcd4097c-f797-42f4-84c8-da1472ccb75d","Sensing Care Through Design: A Speculative Role-play Approach to ""Living with"" Sensor-supported Care Networks","Rattay, Sonja (University of Copenhagen); Collins, Robert (Umeå University); Surana, Aditi (University of Edinburgh); Lee, Youngsil (University of Edinburgh); Liu, Y. (TU Delft Human Information Communication Design); Mauri, Andrea (Université Claude Bernard Lyon 1); Urquhart, Lachlan D (University of Edinburgh); Vines, John (University of Edinburgh); Wilson, Cara (University of Edinburgh); Pschetz, Larissa (University of Edinburgh); Rozendaal, M.C. (TU Delft Human Information Communication Design); Shklovski, Irina (University of Copenhagen)","Byrne, D. (editor); Martelaro, N. (editor)","2023","Sensor networks are increasingly commonplace in visions of smart cities and future healthcare systems, promising greater efficiency and increased wellbeing. However, the design of these technologies remains focused on specific users and fragmented by context, overlooking the diversity of needs, wants and values present when technologies, people, and lived realities interact within instrumented spaces. In this paper we present a workshop method – Sensing Care – that can help researchers, interdisciplinary design and development teams, and potentially affected users, to explore what it takes to design for living with sensor technologies that intersect and interact across private and public spaces, through speculative scenarios and role play. Drawing from three deployments of the workshop, we discuss how this approach supports the design of future care-oriented sensor networks, and helps designers understand what it means to live with complex technologies as people traverse diverse contexts.","Design methods; location-aware computing; contextual computing","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.","","2024-01-10","","","Human Information Communication Design","","",""
"uuid:6117a259-668a-4a38-aa1b-110b8d1057a7","http://resolver.tudelft.nl/uuid:6117a259-668a-4a38-aa1b-110b8d1057a7","A learning algorithm for the calibration of internal model uncertainties in advanced wind turbine controllers: A wind speed measurement-free approach","Mulders, S.P. (TU Delft Team Mulders); Brandetti, L. (TU Delft Wind Energy); Spagnolo, F. (Vestas Wind Systems); Liu, Y. (TU Delft Team Riccardo Ferrari); Christensen, P.B. (Vestas Wind Systems); van Wingerden, J.W. (TU Delft Team Jan-Willem van Wingerden)","","2023","Wind turbine partial-load controllers have evolved from simple static nonlinear function implementations to more advanced dynamic controller structures. Such dynamic control schemes have the potential to improve power production performance in realistic environmental conditions and allow for a more granular trade-off between loads and energy capture. The control structure generally consists of a wind speed estimator (WSE) combined with a controller aiming to track the commanded tip-speed ratio (TSR) reference. The performance and resulting closed-loop system stability are however highly dependent on the accuracy of the internal model in the WSE-TSR tracking scheme. Therefore, developing learning algorithms to calibrate the internal model is of particular interest. Previous works have proposed such algorithms; however, they all rely on the availability of (rotor-effective) wind speed measurements. For the first time, this paper proposes an excitation-based learning algorithm that exploits the closed-loop dynamic structure of the WSE-TSR tracking scheme. This algorithm calibrates the internal model without the need for wind speed measurements. Analysis and simulations show that the proposed algorithm corrects for model uncertainties in the form of magnitude scaling errors under ideal constant and realistic turbulent wind conditions.","","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.","","2024-01-03","","","Team Mulders","","",""
"uuid:e530e4e5-8720-4d39-be12-c40466d374e0","http://resolver.tudelft.nl/uuid:e530e4e5-8720-4d39-be12-c40466d374e0","Workshop on Understanding and Mitigating Cognitive Biases in Human-AI Collaboration","Boonprakong, Nattapat (University of Melbourne); He, G. (TU Delft Web Information Systems); Gadiraju, Ujwal (TU Delft Web Information Systems); Van Berkel, Niels (Aalborg University); Wang, Danding (Chinese Academy of Sciences); Chen, Si (University of Illinois at Urbana-Champaign); Liu, Jiqun (University of Oklahoma); Tag, Benjamin (Monash University); Goncalves, Jorge (University of Melbourne); Dingler, Tilman (University of Melbourne)","Ames, Morgan (editor); Fussell, Susan (editor); Gilbert, Eric (editor); Liao, Vera (editor); Ma, Xiaojuan (editor); Page, Xinru (editor); Rouncefield, Mark (editor); Singh, Vivek (editor); Wisniewski, Pamela (editor)","2023","AI systems are increasingly incorporated into human decision-making. Yet, human decision-makers are often affected by their cognitive biases. In critical settings, such as medical diagnosis, criminal judgment, or information consumption, these cognitive biases hinder optimal decision outcomes, thereby resulting in dangerous decisions and negative societal impact. The use of AI systems can amplify and exacerbate cognitive biases in their users. In this workshop, we seek to foster discussions on ongoing research around cognitive biases in human-AI collaboration and identify future research directions to understand, quantify, and mitigate the effects of cognitive biases. We will explore cognitive biases appearing in various contexts of human-AI collaboration: what can cause them?; how can we measure, model, mitigate, and manage cognitive biases?; and how can we utilise cognitive biases for the greater good? We will reflect on workshop discussions to form a research community around cognitive biases and bias-aware systems.","Cognitive Bias; Debiasing; Human-AI Collaboration","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Web Information Systems","","",""
"uuid:7b63cfed-7fb7-4305-be31-80feeda78a47","http://resolver.tudelft.nl/uuid:7b63cfed-7fb7-4305-be31-80feeda78a47","A control-oriented wind turbine dynamic simulation framework which resolves local atmospheric conditions","Feng, Z. (TU Delft Team Riccardo Ferrari); Ferrari, Riccardo M.G. (TU Delft Team Riccardo Ferrari); van Wingerden, J.W. (TU Delft Team Jan-Willem van Wingerden); Liu, Y. (Electeic Power Research Institute)","Soares, C. Guedes (editor)","2023","Wind turbines may experience local weather perturbation, which is not taken into account by the commonly-used wind turbine simulation packages. Without this information, it is extremely challenging to evaluate the controller performance with regard to the effect of the variation of local atmospheric conditions. On the other side, it is too late and costly to wait until field test time. To fill this gap, in this paper, we develop a control-oriented turbine dynamic simulation framework to evaluate the controller performance considering the perturbation of local atmospheric conditions. This goal is achieved by integrating an internal wind turbine (IWT) model in the Weather Research and Forecasting (WRF) simulation tool. The proposed framework is implemented on a 5MW reference wind turbine, where the effects of the local atmospheric conditions are illustrated. The proposed WRF-IWT model are validated by comparing the results with those derived from the Fatigue, Aerodynamics, Structures, and Turbulence (FAST).","","en","conference paper","CRC Press / Balkema - Taylor & Francis Group","","","","","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.","","2023-05-02","","","Team Riccardo Ferrari","","",""
"uuid:ee398f73-31f5-4d0c-9c91-842486d6b6b2","http://resolver.tudelft.nl/uuid:ee398f73-31f5-4d0c-9c91-842486d6b6b2","Single-ended DC Fault Location Method For MMC-Based HVDC Power System Using Adaptive Multi-step Levenberg-Marquardt Algorithm","Liu, L. (TU Delft Intelligent Electrical Power Grids); Xie, F. (TU Delft Intelligent Electrical Power Grids; Xi’an Jiaotong University); Popov, M. (TU Delft Intelligent Electrical Power Grids); Hao, Zhiguo (Xi’an Jiaotong University); Lekić, A. (TU Delft Intelligent Electrical Power Grids)","","2023","This article presents an accurate DC fault location method that applies parameter fitting. This technique first discusses the traveling wave (TW) propagation process in the decoupled line-mode network. We obtain the exact fault distance equation based on the analytical expressions for the wavefront of backward line-mode voltage TW. The adaptive multi-step Levenberg- Marquardt's (AMLM) algorithm is used for parameter fitting due to its fast processing speed and accuracy. The exact fault location can then be estimated using the parameter fitting results. The proposed fault location method is validated using a three-terminal HVDC system modeled on a real-time digital simulator (RTDS) platform. Based on the experimental results, the proposed method accurately detects the fault location, with all estimated errors smaller than 1%, and can withstand 40 dB noise interference. Moreover, the proposed method does not need a high sampling frequency and communication device. Its accuracy is independent of fault resistance and type compared to existing methods.","HVDC; VSC; backward traveling wave; DC fault location; parameter fitting; Levenberg-Marquardt; RTDS","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.","","2024-02-09","","","Intelligent Electrical Power Grids","","",""
"uuid:1517fcd8-6559-4de9-8c86-244f32e687c6","http://resolver.tudelft.nl/uuid:1517fcd8-6559-4de9-8c86-244f32e687c6","Recyclability of epoxy-modified open-graded porous asphalt","Jing, R. (TU Delft Pavement Engineering); Apostolidis, P. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Naus, R. (Dura Vermeer); Erkens, S. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University)","","2023","Epoxy asphalt attracted the attention of road authorities in many countries as a solution for du-rable open-graded porous asphalt (OGPA) surface layers with enhanced longevity. Nevertheless, the recycla-bility of aged epoxy asphalt materials has not been thoroughly studied yet. This research presents an experi-mental program conducted in the laboratory to assess the potential recyclability of epoxy-modified open-graded porous asphalt (EMOGPA) mixes. Results indicate that the aging increased the tensile strength of studied mixes, with the strength and strength development rate of aging EMOGPA mixes to be almost identi-cal to standard OGPA mixes. The EMOGPA mixes have shown higher resistance against water damage than the OGPA mixes supporting the claim that the stone-mastic adhesion is improved with the use of epoxy bind-er. It was also proven that the aged material containing the epoxy binder could be re-melted to produce new pavement materials. The new EMOGPA mixes with the recycled epoxy material exhibited similar durability characteristics with the recycled standard OGPA mixes.","","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.","","2023-11-24","","","Pavement Engineering","","",""
"uuid:8b66a4c1-eabe-49a2-8af1-24ddd275ebbb","http://resolver.tudelft.nl/uuid:8b66a4c1-eabe-49a2-8af1-24ddd275ebbb","Objects do not disappear: Video object detection by single-frame object location anticipation","Liu, X. (TU Delft Pattern Recognition and Bioinformatics); van Gemert, J.C. (TU Delft Pattern Recognition and Bioinformatics); Nejadasl, Fatemeh Karimi (Universiteit van Amsterdam); Booij, O. (TU Delft Pattern Recognition and Bioinformatics); Pintea, S. (TU Delft Pattern Recognition and Bioinformatics)","Ceballos, Cristina (editor)","2023","Objects in videos are typically characterized by continuous smooth motion. We exploit continuous smooth motion in three ways. 1) Improved accuracy by using object motion as an additional source of supervision, which we obtain by anticipating object locations from a static keyframe. 2) Improved efficiency by only doing the expensive feature computations on a small subset of all frames. Because neighboring video frames are often redundant, we only compute features for a single static keyframe and predict object locations in subsequent frames. 3) Reduced annotation cost, where we only annotate the keyframe and use smooth pseudo-motion between keyframes. We demonstrate computational efficiency, annotation efficiency, and improved mean average precision compared to the state-of-the-art on four datasets: ImageNet VID, EPIC KITCHENS-55, YouTube-BoundingBoxes and Waymo Open dataset. Our source code is available at https://github.com/L-KID/Video-object-detection-by-location-anticipation.","","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.","","2024-07-15","","","Pattern Recognition and Bioinformatics","","",""
"uuid:38545a77-f02a-41df-bbfc-ec3c6bd9f16f","http://resolver.tudelft.nl/uuid:38545a77-f02a-41df-bbfc-ec3c6bd9f16f","A review of vision-based road detection technology for unmanned vehicles","Liu, Chaoyang (Beijing Institute of Technology); Li, Xueyuan (Beijing Institute of Technology); Liu, Qi (Beijing Institute of Technology); Yang, Fan (Beijing Institute of Technology); Li, Z. (TU Delft Transport and Planning); Li, Mengkai (Beijing Institute of Technology)","","2023","With the development of unmanned vehicle technology, unmanned vehicles have played a huge role in logistics transportation, emergency rescue and disaster relief, etc., so the research on unmanned vehicles is becoming more and more important. Road detection is an important part of environmental perception and an important factor in the realization of assisted driving and unmanned driving technology. High-precision road detection technology can provide important environmental information for efficient planning and reasonable decision-making of unmanned vehicles. Firstly, the technical framework of road detection is given, and the road detection process is introduced in detail. Then, the vision-based road detection algorithm is introduced. Finally, some related data sets in the field of road detection are collected, which provides new ideas and methods for road detection researchers.","data sets; road detection; unmanned vehicle; vision","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.","","2023-12-07","","","Transport and Planning","","",""
"uuid:3ae2da81-d8ac-47cc-9ad0-e6b03724c81c","http://resolver.tudelft.nl/uuid:3ae2da81-d8ac-47cc-9ad0-e6b03724c81c","Video BagNet: Short temporal receptive fields increase robustness in long-term action recognition","Strafforello, O. (TU Delft Pattern Recognition and Bioinformatics; TNO); Liu, X. (TU Delft Pattern Recognition and Bioinformatics); Schutte, Klamer (TNO); van Gemert, J.C. (TU Delft Pattern Recognition and Bioinformatics)","Ceballos, Cristina (editor)","2023","Previous work on long-term video action recognition relies on deep 3D-convolutional models that have a large temporal receptive field (RF). We argue that these models are not always the best choice for temporal modeling in videos. A large temporal receptive field allows the model to encode the exact sub-action order of a video, which causes a performance decrease when testing videos have a different sub-action order. In this work, we investigate whether we can improve the model robustness to the sub-action order by shrinking the temporal receptive field of action recognition models. For this, we design Video BagNet, a variant of the 3D ResNet-50 model with the temporal receptive field size limited to 1, 9, 17 or 33 frames. We analyze Video Bag-Net on synthetic and real-world video datasets and experimentally compare models with varying temporal receptive fields. We find that short receptive fields are robust to sub-action order changes, while larger temporal receptive fields are sensitive to the sub-action order.","","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.","","2024-06-25","","","Pattern Recognition and Bioinformatics","","",""
"uuid:e413dd39-cceb-4e60-b689-11820ad27f04","http://resolver.tudelft.nl/uuid:e413dd39-cceb-4e60-b689-11820ad27f04","Polymer Reinforced Solder Paste for Improving Impact Energy Absorption Capability in Micro LED Laser-Assisted Mass Transfer","Ji, Liangzheng (Fudan University; Heraeus Materials Technology Shanghai Ltd.); Li, Zaihuan (Heraeus Materials Technology Shanghai Ltd.); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Zhang, Jing (Heraeus Materials Technology Shanghai Ltd.); Liu, Pan (Fudan University)","","2023","Micro LED displays offer superior performance compared to traditional LCD and OLED displays. However, challenges in transfer technology, such as high throughput and scalability, must be addressed. Among various mass transfer techniques, stamp transfer and laser-assisted transfer are widely used for Micro LED assembly. The laser-assisted transfer technique enables high-speed and accurate transfer. Anisotropic conductive film (ACF) is commonly used for its energy absorption properties during chip transfer. However, during the subsequent thermocompression bonding process, the ACF film needs to be ruptured, which adds no value to the bonding process. To address limitations, we have developed a polymer-reinforced solder paste that demonstrates high effectiveness in absorbing impact energy during chip dropping, providing performance comparable to ACF-like materials for die receiving. It also possesses typical solder paste characteristics, enabling the formation of reliable solder joints between the chip and substrate. This material facilitates streamlined manufacturing process and providing opportunities for chip rework in subsequent stages.","","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.","","2024-07-17","","","Electronic Components, Technology and Materials","","",""
"uuid:3631b057-6e20-470a-acec-ceb3476a1137","http://resolver.tudelft.nl/uuid:3631b057-6e20-470a-acec-ceb3476a1137","3ET: Efficient Event-based Eye Tracking using a Change-Based ConvLSTM Network","Chen, Qinyu (University of Zürich; ETH Zürich); Wang, Zuowen (University of Zürich; ETH Zürich); Liu, Shih Chii (University of Zürich; ETH Zürich); Gao, C. (TU Delft Electronics)","","2023","This paper presents a sparse Change-Based Convolutional Long Short-Term Memory (CB-ConvLSTM) model for event-based eye tracking, key for next-generation wearable healthcare technology such as AR/VR headsets. We leverage the benefits of retina-inspired event cameras, namely their low-latency response and sparse output event stream, over traditional frame-based cameras. Our CB-ConvLSTM architecture efficiently extracts spatio-temporal features for pupil tracking from the event stream, outperforming conventional CNN structures. Utilizing a delta-encoded recurrent path enhancing activation sparsity, CB-ConvLSTM reduces arithmetic operations by approximately 4.7× without losing accuracy when tested on a v2e-generated event dataset of labeled pupils. This increase in efficiency makes it ideal for real-time eye tracking in resource-constrained devices. The project code and dataset are openly available at https://github.com/qinche106/cb-convlstm-eyetracking.","Pupil tracking; event cameras; sparsity; ConvLSTM; healthcare; AR/VR","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.","","2024-07-18","","","Electronics","","",""
"uuid:fbe87cba-3290-4c31-a66e-6cd5174ae249","http://resolver.tudelft.nl/uuid:fbe87cba-3290-4c31-a66e-6cd5174ae249","Practice of Planning Coordination for Crossborder Spatial Governance in the Yangtze River Delta Region: A Transformative Analysis in Meta-Governance","Su, D. (TU Delft Urban Development Management; Tsinghua University); Liu, Jian (Tsinghua University)","","2023","Nowadays, city clusters have become an important spatial form in the process of global urbanization, characterized by contiguous development across provincial, municipal, and county administrative boundaries, given all-around cross-border circulation of socio-economic factors at the regional scale has become the trend. In order to pursue their own interests, neighboring administrative regions are driven by localism and often deliberately ignore regional level neighborhood issues, especially ecological and environmental issues regarding “public goods”, coupled with weak cross-border spatial governance at the regional level, this has led to prominent negative externalities and constant conflicts in the development of cross-border areas, seriously affecting the developing quality of the region as a whole. This paper attempts to challenge the traditional technical concept of spatial planning, and introduce the meta-governance theory of public administration discipline. The study empirically demonstrates the Yangtze River Delta(YRD), the representative of China’s regional development and pioneer in cross-border ecological governance as an example, and identifies the evolution of the three-stage regional coordination model in the YDR region since the reform and opening up in China, and the successes and failures of planning meta-governance in the cross-border area under different goal-oriented approaches. This paper summarizes a regional planning meta-governance model with Chinese characteristics, to explore the mechanism of spatial planning, as a policy and technical tool for spatial governance, in responding to the ecological governance of crossborder space, and measures how it can effectively play a synergistic role in the regional scale.","Yangtze River Delta; cross-border; spatial governance; meta-governance; regional planning; spatial planning; coordination","en","conference paper","ENSAP Bordeaux","","","","","","","","","","Urban Development Management","","",""
"uuid:f53b6aea-4799-4404-9cbf-dcf6d5a85242","http://resolver.tudelft.nl/uuid:f53b6aea-4799-4404-9cbf-dcf6d5a85242","Adaptive Risk-Tendency: Nano Drone Navigation in Cluttered Environments with Distributional Reinforcement Learning","Liu, C. (TU Delft Control & Simulation); van Kampen, E. (TU Delft Control & Simulation); de Croon, G.C.H.E. (TU Delft Control & Simulation)","","2023","Enabling the capability of assessing risk and making risk-aware decisions is essential to applying reinforcement learning to safety-critical robots like drones. In this paper, we investigate a specific case where a nano quadcopter robot learns to navigate an apriori-unknown cluttered environment under partial observability. We present a distributional reinforcement learning framework to generate adaptive risk-tendency policies. Specifically, we propose to use lower tail conditional variance of the learnt return distribution as intrinsic uncertainty estimation, and use exponentially weighted average forecasting (EWAF) to adapt the risk-tendency in accordance with the estimated uncertainty. In simulation and real-world empirical results, we show that (1) the most effective risk-tendency varies across states, (2) the agent with adaptive risk-tendency achieves superior performance compared to risk-neutral policy or risk-averse policy baselines. Code and video can be found in this repository: https://github.com/tudelft/risk-sensitive-rl.git","","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:580e5a49-5028-45fa-bcf6-0747836ecf40","http://resolver.tudelft.nl/uuid:580e5a49-5028-45fa-bcf6-0747836ecf40","An Area-Efficient Ultra-Low-Power Time-Domain Feature Extractor for Edge Keyword Spotting","Chen, Qinyu (University of Zürich); Chang, Yaoxing (University of Zürich); Kim, Kwantae (University of Zürich); Gao, C. (TU Delft Electronics); Liu, Shih Chii (University of Zürich)","","2023","Keyword spotting (KWS) is an important task on edge low-power audio devices. A typical edge KWS system consists of a front-end feature extractor which outputs mel-scale frequency cepstral coefficients (MFCC) features followed by a back-end neural network classifier. KWS edge designs aim for the best power-performance-area metrics. This work proposes an area-efficient ultra-low-power time-domain infinite impulse response (IIR) filter-based feature extractor for a KWS system. It uses a serial architecture, and the architecture is further optimized for a low-cost computing structure and mixed-precision bit selection of the IIR coefficients while maintaining good KWS accuracy. Using a 65 nm process technology and a back-end neural network classifier, this simulated feature extractor has an area of 0.02 mm2 and achieves 3.3 μW @ 1.2 V, and achieves 92.5% accuracy on a 10-keyword, 12-class KWS task using the GSCD dataset.","hardware acceleration; infinite impulse response (IIR); Keyword spotting (KWS); long short-term memory","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.","","2024-01-22","","","Electronics","","",""
"uuid:20817bd2-c257-48d8-8efe-0a55993f3fe0","http://resolver.tudelft.nl/uuid:20817bd2-c257-48d8-8efe-0a55993f3fe0","FedKNOW: Federated Continual Learning with Signature Task Knowledge Integration at Edge","Luopan, Yaxin (Beijing Institute of Technology); Han, Rui (Beijing Institute of Technology); Zhang, Qinglong (Beijing Institute of Technology); Liu, Chi Harold (Beijing Institute of Technology); Wang, Guoren (Beijing Institute of Technology); Chen, Lydia Y. (TU Delft Data-Intensive Systems)","","2023","Deep Neural Networks (DNNs) have been ubiquitously adopted in internet of things and are becoming an integral of our daily life. When tackling the evolving learning tasks in real world, such as classifying different types of objects, DNNs face the challenge to continually retrain themselves according to the tasks on different edge devices. Federated continual learning is a promising technique that offers partial solutions but yet to overcome the following difficulties: the significant accuracy loss due to the limited on-device processing, the negative knowledge transfer caused by the limited communication of non-IID data, and the limited scalability on the tasks and edge devices. In this paper, we propose FedKNOW, an accurate and scalable federated continual learning framework, via a novel concept of signature task knowledge. FedKNOW is a client side solution that continuously extracts and integrates the knowledge of signature tasks which are highly influenced by the current task. Each client of FedKNOW is composed of a knowledge extractor, a gradient restorer and, most importantly, a gradient integrator. Upon training for a new task, the gradient integrator ensures the prevention of catastrophic forgetting and mitigation of negative knowledge transfer by effectively combining signature tasks identified from the past local tasks and other clients' current tasks through the global model. We implement FedKNOW in PyTorch and extensively evaluate it against state-of-the-art techniques using popular federated continual learning benchmarks. Extensive evaluation results on heterogeneous edge devices show that FedKNOW improves model accuracy by 63.24% without increasing model training time, reduces communication cost by 34.28%, and achieves more improvements under difficult scenarios such as large numbers of tasks or clients, and training different complex networks.","communication; continual learning; deep neural networks; 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","","","Data-Intensive Systems","","",""
"uuid:49124128-422f-4f6e-8ef2-45142046fe5d","http://resolver.tudelft.nl/uuid:49124128-422f-4f6e-8ef2-45142046fe5d","EdgeVisionBench: A Benchmark of Evolving Input Domains for Vision Applications at Edge","Zhang, Qinglong (Beijing Institute of Technology); Han, Rui (Beijing Institute of Technology); Liu, Chi Harold (Beijing Institute of Technology); Wang, Guoren (Beijing Institute of Technology); Chen, Lydia Y. (TU Delft Data-Intensive Systems)","","2023","Vision applications powered by deep neural networks (DNNs) are widely deployed on edge devices and solve the learning tasks of incoming data streams whose class label and input feature continuously evolve, known as domain shift. Despite its prominent presence in real-world edge scenarios, existing benchmarks used by domain adaptation methods overlook evolving domains and under represent their shifts in label and feature distributions. To address this gap, we present EdgeVisionBench, a benchmark seeking to generate evolving domains of various types and reflect their realistic label and feature shifts encountered by edge-based vision applications. To facilitate evaluating domain adaptation methods on edge devices, we provide an open-source package that automates workload generation, contains popular DNN models and compression techniques, and standardizes evaluations with interactive interfaces. Code and datasets are available at https://github.com/LINC-BIT/EdgeVisionBench.","benchmark; Edge computing; evolving domains; vision applications","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","","","Data-Intensive Systems","","",""
"uuid:3dd9647a-22d7-4589-87a5-fd7c9cbfce4f","http://resolver.tudelft.nl/uuid:3dd9647a-22d7-4589-87a5-fd7c9cbfce4f","Simulation, Prediction, and Verification of the Corrosion Behavior of Cu-Ag Composite Sintered Paste for Power Semiconductor Die-attach Applications","Wang, Xinyue (Fudan University); Yang, Zhoudong (Fudan University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Zhang, Jing (Heraeus Materials Technology Shanghai Ltd.); Liu, Pan (Fudan University)","","2023","With the popularization of wide band-gap power modules in offshore wind power systems and water surface photovoltaic power stations, packaging materials face challenges of corrosion by salt, blended with high humidity. Copper-silver (Cu-Ag) composite sintered paste was proposed by researchers as a novel die-attach material for a lower cost and anti-electro migration ability. However, the potential difference between copper and silver forms galvanic corrosion in a high-humidity environment, resulting in accelerated failure combined with salt mist. To further promote the application of composite sintered materials, a copper-silver double-sphere galvanic corrosion model based on finite element simulation was proposed in this paper. The relationship between corrosion rate and time of different Cu-Ag particle size combinations under different sintering degrees was predicted by initial exchange current density. Through the electrochemical characterization of the sintered samples, the optimal combination of materials was further discussed. The accuracy of the model was also verified. The conclusions obtained from both the experiments and simulation work provide guidance for future anti-corrosion analysis, as well as the reliability improvement of novel composite sintered materials.","die-attach material; FEM simulation; galvanic corrosion; power electronic packaging","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.","","2023-11-30","","","Electronic Components, Technology and Materials","","",""
"uuid:3e54aaa0-46f8-4411-a5ca-351a314d73ce","http://resolver.tudelft.nl/uuid:3e54aaa0-46f8-4411-a5ca-351a314d73ce","The Multimodal Information Based Speech Processing (Misp) 2022 Challenge: Audio-Visual Diarization And Recognition","Wang, Zhe (University of Science and Technology of China); Wu, Shilong (University of Science and Technology of China); Chen, Hang (University of Science and Technology of China); He, Mao-Kui (University of Science and Technology of China); Du, Jun (University of Science and Technology of China); Lee, Chin-Hui (Georgia Institute of Technology); Chen, Jingdong (Northwestern Polytechnical University); Watanabe, Shinji (Carnegie Mellon University); Siniscalchi, Sabato Marco (Georgia Institute of Technology; University of Enna Kore); Scharenborg, O.E. (TU Delft Multimedia Computing); Liu, Diyuan (iFlytek)","","2023","The Multi-modal Information based Speech Processing (MISP) challenge aims to extend the application of signal processing technology in specific scenarios by promoting the research into wake-up words, speaker diarization, speech recognition, and other technologies. The MISP2022 challenge has two tracks: 1) audio-visual speaker diarization (AVSD), aiming to solve ""who spoken when"" using both audio and visual data; 2) a novel audio-visual diarization and recognition (AVDR) task that focuses on addressing ""who spoken what when"" with audio-visual speaker diarization results. Both tracks focus on the Chinese language, and use far-field audio and video in real home-tv scenarios: 2-6 people communicating each other with TV noise in the background. This paper introduces the dataset, track settings, and baselines of the MISP2022 challenge. Our analyses of experiments and examples indicate the good performance of AVDR baseline system, and the potential difficulties in this challenge due to, e.g., the far-field video quality, the presence of TV noise in the background, and the indistinguishable speakers.","MISP challenge; speaker diarization; speech recognition; multimodality","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","","","Multimedia Computing","","",""
"uuid:47defb3b-2b9f-4b0a-9628-6e49ad733b2c","http://resolver.tudelft.nl/uuid:47defb3b-2b9f-4b0a-9628-6e49ad733b2c","Real-time Routing and Scheduling of On-demand Autonomous Customized Bus Systems","Guo, Rongge (University of Huddersfield); Liu, X. (TU Delft Team Bart De Schutter); Bhatnagar, Saumya (University of Huddersfield); Vallati, Mauro (University of Huddersfield)","","2023","The integration of autonomous vehicles and on-demand customized bus systems is expected to be beneficial for responding to real-time demands. This paper investigates the autonomous customized bus (ACB) system that leverages passenger demand prediction to enhance service quality and vehicle utilization. A novel ACB service design optimization model that determines vehicle movements and passenger-to-vehicle assignments is developed for the real-time routing and scheduling problem. Then, a rolling horizon approach, incorporating travel demand prediction, proactive dispatching and reactive adjustment, is proposed to address the studied problem. The performance of the introduced ACB system is evaluated using smartcard data from Beijing and the state-of-the-art machine learning algorithm. Results show that the proposed ACB system can effectively improve system performance and service level in terms of operating cost and passenger waiting time compared to reactive operations.","","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.","","2024-08-13","","","Team Bart De Schutter","","",""
"uuid:3d399b07-466c-4181-8b9d-abee0280415d","http://resolver.tudelft.nl/uuid:3d399b07-466c-4181-8b9d-abee0280415d","Benders Decomposition-Based Optimization of Train Departure Frequencies in Metro Networks","Daman, A. (Student TU Delft); Liu, X. (TU Delft Team Bart De Schutter); Dabiri, A. (TU Delft Team Azita Dabiri); De Schutter, B.H.K. (TU Delft Delft Center for Systems and Control)","","2023","Timetables determine the service quality for passengers and the energy consumption of trains in metro systems. In metro networks, a timetable can be made by designing train departure frequencies for different periods of the day, which is typically formulated as a mixed-integer linear programming (MILP) problem. In this paper, we first apply Benders decomposition to optimize the departure frequencies considering time-varying passenger origin-destination demands in metro networks. An ϵ -optimal Benders decomposition approach is subsequently used to reduce the solution time further. The performance of both methods is illustrated in a simulation-based case study using a grid metro network. The results show that both the classical Benders decomposition approach and the ϵ -optimal Benders decomposition approach can significantly reduce the computation time for the optimization of train departure frequencies in metro networks. In addition, the ϵ -optimal Benders decomposition approach can further reduce the solution time compared to the classical Benders decomposition approach when the problem scale increases while maintaining an acceptable level of performance.","","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.","","2024-08-13","","Delft Center for Systems and Control","Team Bart De Schutter","","",""
"uuid:691514b3-285d-4a75-af82-12d53b3e16ce","http://resolver.tudelft.nl/uuid:691514b3-285d-4a75-af82-12d53b3e16ce","Maverick Matters: Client Contribution and Selection in Federated Learning","Huang, J. (TU Delft Data-Intensive Systems); Hong, C. (TU Delft Data-Intensive Systems); Liu, Yang (Tsinghua University); Chen, Lydia Y. (TU Delft Data-Intensive Systems); Roos, S. (TU Delft Data-Intensive Systems)","Kashima, Hisashi (editor); Ide, Tsuyoshi (editor); Peng, Wen-Chih (editor)","2023","Federated learning (FL) enables collaborative learning between parties, called clients, without sharing the original and potentially sensitive data. To ensure fast convergence in the presence of such heterogeneous clients, it is imperative to timely select clients who can effectively contribute to learning. A realistic but overlooked case of heterogeneous clients are Mavericks, who monopolize the possession of certain data types, e.g., children hospitals possess most of the data on pediatric cardiology. In this paper, we address the importance and tackle the challenges of Mavericks by exploring two types of client selection strategies. First, we show theoretically and through simulations that the common contribution-based approach, Shapley Value, underestimates the contribution of Mavericks and is hence not effective as a measure to select clients. Then, we propose FedEMD, an adaptive strategy with competitive overhead based on the Wasserstein distance, supported by a proven convergence bound. As FedEMD adapts the selection probability such that Mavericks are preferably selected when the model benefits from improvement on rare classes, it consistently ensures the fast convergence in the presence of different types of Mavericks. Compared to existing strategies, including Shapley Value-based ones, FedEMD improves the convergence speed of neural network classifiers with FedAvg aggregation by 26.9% and its performance is consistent across various levels of heterogeneity.","client selection; data heterogeneity; Federated learning; shapley value; wasserstein distance","en","conference paper","Springer","","","","","","","","","","Data-Intensive Systems","","",""
"uuid:e6245999-4884-497d-a53d-5b7294b64cc6","http://resolver.tudelft.nl/uuid:e6245999-4884-497d-a53d-5b7294b64cc6","Formation Control of Skid-Steered Vehicles Based on Distributed Model Predictive Control","Wang, Yiping (Beijing Institute of Technology); Li, Xueyuan (Beijing Institute of Technology); Liu, Qi (Beijing Institute of Technology); Li, Songhao (Beijing Institute of Technology); Luan, Tian (Beijing Institute of Technology); Li, Z. (TU Delft Transport and Planning; Beijing Institute of Technology)","Fu, Wenxing (editor); Gu, Mancang (editor); Niu, Yifeng (editor)","2023","The skid-steered vehicle has the advantages of simple structure and strong maneuverability. Its formation driving can effectively improve safety, reduce energy consumption and exert its benefits, and has wide application prospects in military and civilian fields. Differential skid steering has strong horizontal and vertical coupling characteristics, so the tracking performance of the vehicle is poor. Therefore, it is of great significance to study horizontal and vertical joint control. Firstly, the mathematical model of the vehicle platoon is established to realize the formation control of skid-steered vehicles. Then, a combined horizontal and vertical control strategy for skid-steered vehicle formation is proposed, and a distributed model predictive controller is designed. Finally, simulation experiments verified that the designed method has good feasibility and stability.","Distributed model predictive control; Formation driving; Lateral and longitudinal control; Skid-steered vehicle","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","","","Transport and Planning","","",""
"uuid:4ef8308f-ca44-4701-8253-87790026ce90","http://resolver.tudelft.nl/uuid:4ef8308f-ca44-4701-8253-87790026ce90","Photogrammetric Reconstruction of a Stolen Statue","Liu, Z. (TU Delft Emerging Materials; Centre for Perceptual and Interactive Intelligence Limited, Hong Kong); Doubrovski, E.L. (TU Delft Mechatronic Design); Geraedts, Jo M.P. (TU Delft Emerging Materials); Yam, Y (Centre for Perceptual and Interactive Intelligence Limited, Hong Kong); Wang, W. (The Chinese University of Hong Kong; Centre for Perceptual and Interactive Intelligence Limited, Hong Kong); Wang, C.C.L. (The University of Manchester)","Babaei, V. (editor); Skouras, M. (editor)","2023","In this paper, we propose a method to reconstruct a digital 3D model of a stolen/damaged statue using photogrammetric methods. This task is challenging because the number of available photos for a stolen statue is in general very limited – especially the side/back view photos. Besides using standard structure-from-motion and multi-view stereo methods, we match image pairs with low overlap using sliding windows and maximize the normalized cross-correlation (NCC) based patch-consistency so that the image pairs can be well aligned into a complete model to build the 3D mesh surface. Our method is based on the prior of the planar side on the statue’s pedestal, which can cover a large range of statues. We hope this work will motivate more research efforts for the reconstruction of those stolen/damaged statues and heritage preservation.","Computing methodologies; Reconstruction; Mesh models","en","conference paper","","","","","","","","","","","Mechatronic Design","","",""
"uuid:995dd9ea-d934-41f7-954c-7219f86bffbd","http://resolver.tudelft.nl/uuid:995dd9ea-d934-41f7-954c-7219f86bffbd","Non-Unit DC Line Protection Method for Multi-Terminal MMC-HVDC System Based on Normalized Backward Traveling Waves","Xie, F. (TU Delft Intelligent Electrical Power Grids; Xi’an Jiaotong University); Liu, L. (TU Delft Intelligent Electrical Power Grids); Hao, Zhiguo (Xi’an Jiaotong University); Lekić, A. (TU Delft Intelligent Electrical Power Grids); Popov, M. (TU Delft Intelligent Electrical Power Grids)","","2023","Existing line protection methods for multi-terminal direct current (MTDC) systems are constrained by the placement and values of boundary elements. To overcome this limitation, this paper proposes a non-unit DC line protection method based on the normalized backward traveling waves (BTWs) of the 1-mode voltage. Firstly, this article studies the traveling wave characteristics and derives the expressions for the normalized BTWs. Then, the Levenberg-Marquardt algorithm is used for amplitude fitting and normalization calculation. Based on the normalized BTWs, a non-unit protection method is proposed. Finally, the proposed method is evaluated with a simulation model on the PSCAD/EMTDC platform. The results demonstrate that the proposed method can accurately identify faults of different resistances and distances without requiring boundary devices, and is robust against noise disturbances (35 dB).","Levenberg-Marquardt algorithm; Modular multilevel converter; Multi-terminal DC grid; Non-unit protection; Traveling wave","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.","","2024-07-29","","","Intelligent Electrical Power Grids","","",""
"uuid:495ad310-4284-486f-bf67-c03a6effff90","http://resolver.tudelft.nl/uuid:495ad310-4284-486f-bf67-c03a6effff90","HER-PDQN: A Reinforcement Learning Approach for UAV Navigation with Hybrid Action Spaces and Sparse Rewards","Liu, C. (TU Delft Control & Simulation); van Kampen, E. (TU Delft Control & Simulation)","","2022","Reinforcement learning (RL) equipped with neural networks has recently led to a wide range of successes in learning policies for unmanned aerial vehicle (UAV) navigation and control problems. The success of RL relies on two human-designed heuristics: appropriate action space definition and reward function engineering. The commonly used fully continuous or fully discrete action spaces in optimal control and decision making problems may lack control authority and remove the inherent problem structure, which can negatively affect learning performance. Besides, reward engineering requires a lot of human effort and may lead to unwanted behavior. In this paper, we address these challenges by proposing a new off-policy RL algorithm called HER-PDQN which incorporates Hindsight Experience Replay (HER) with Parameterized Deep Q-Networks (P-DQN). In simulation experiments, HER-PDQN is used to train an agent to fulfill a UAV navigation task in a 2-dimensional environment. The results indicate the effectiveness of P-DQN algorithm in dealing both with the hybrid action space and sparse rewards. This paper can be considered as the first attempt at applying RL in sparse reward setting for UAV navigation with hybrid action spaces.","","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.","","2023-07-01","","","Control & Simulation","","",""
"uuid:f5f9693b-025e-49b7-b3ae-1d36b87f6f36","http://resolver.tudelft.nl/uuid:f5f9693b-025e-49b7-b3ae-1d36b87f6f36","High-Voltage and High-Current IGBT Press-pack Module for Power Grid","Tan, C. (TU Delft Electronic Components, Technology and Materials; Southern University of Science and Technology); Wang, S. (TU Delft Bio-Electronics; Southern University of Science and Technology); Liu, X. (TU Delft Electronic Components, Technology and Materials; Southern University of Science and Technology); Jiang, Jing (Fudan University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Ye, H. (TU Delft Electronic Components, Technology and Materials; Chongqing University)","","2022","On the basis of the development and application requirements of flexible DC transmission techniques, a 1 kA/10 kV half-bridge IGBT press-pack module is studied. The module is composed of three subunits in series, and each subunit consists of IGBT chips in parallel. In order to solve the problem of chips failure caused by non-uniform rigid-contacting pressure in the press-pack modules, the elastic-contacting structure is designed to ensure excellent electrical connection between chips and contact terminal. During the operating conditions, the heat generated by IGBT chips can induce the increasing of internal temperature of the module, affecting the reliability of the module. A cooling structure is introduced between the subunits to solve the heat dissipation problem of the module. In addition, the thermal analysis of subunit and the cooling structure is performed by using the finite element simulation, and the chip layout and water-cooling scheme are optimized. The testing of electrical parameters of the IGBT module is also conducted.","","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","","","Electronic Components, Technology and Materials","","",""
"uuid:30b3f7a8-2d97-4b96-acca-d84074d2bd15","http://resolver.tudelft.nl/uuid:30b3f7a8-2d97-4b96-acca-d84074d2bd15","Effects of shell thickness on the thermal stability of Cu-Ag core-shell nanoparticles: A molecular dynamics study","Li, Shizhen (Southern University of Science and Technology); Liu, X. (TU Delft Electronic Components, Technology and Materials; Southern University of Science and Technology); Jiang, Jing (Fudan University); Tan, C. (TU Delft Electronic Components, Technology and Materials; Southern University of Science and Technology); Gao, Chenshan (Chongqing University; Southern University of Science and Technology); Liu, Yang (Harbin University of Science and Technology); Ye, H. (Southern University of Science and Technology; Chongqing University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2022","Cu-Ag core-shell (CS) nanoparticle (NP) is considered as a cost-effective alternative material to nano silver sintering material in die attachment application. To further reduce the cost, the thickness of the Ag shell can be adjusted. Whereas the shell thickness will also affect the thermal stability of the Cu-Ag CSNPs. In this study, molecular dynamics simulation was applied to study the thickness effect on the thermal behavior of Cu-Ag CSNPs. The melting points of CSNPs and Pure NPs can be determined by the evolutions of Potential Energy (PE), and the Lindemann index (LI) of the system. The results indicated that the melting points of CS NPs were lower than monometallic NP and the melting point of CS NP is influenced by the size of the Cu core and the number of lattice mismatches. Moreover, the distribution of atoms’ LI showed that the premelting point is independent of shell thickness. However, the fraction of atoms that occurred premelting is increased with the decrease of the shell thickness. Otherwise, we also simulated the sintering process of double CS NPs with equal size.","","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","","","Electronic Components, Technology and Materials","","",""
"uuid:bc2a6067-69c5-433c-8251-77ffea0355e2","http://resolver.tudelft.nl/uuid:bc2a6067-69c5-433c-8251-77ffea0355e2","Visualisation of the airflow pattern of exhaled droplets in a classroom","Liu, Y.L. (Student TU Delft); Ortiz, Marco A. (TU Delft Indoor Environment); Zhang, D. (TU Delft Indoor Environment); Bluyssen, P.M. (TU Delft Indoor Environment)","","2022","The airborne transmission of SARS-CoV-2 in educational buildings has raised concerns during the current COVID-19 pandemic. In this study, a portable fog generator system was designed and assembled to visualise the airflow pattern of exhaled droplets in a classroom. The system consists of five components: medium, fog generator, buffer, pump, and manikin head. The medium was made of glycol and demineralised water, which produced a fog composed of droplets. The fog was produced with the fog generator and passed through a pipe into the buffer for build-up. After accumulation, the fog is pumped through another pipe and is exhaled out of the mouth of the manikin. Experiments were conducted with the portable fog generator system in a simulated classroom under four different ventilation regimes: no ventilation, natural ventilation (open windows and door), mixing ventilation (600 m3/h), and a combination of natural + mixing ventilation. The experiments were recorded with a camera and analysed to determine the horizontal distance of the path taken by the fog and to measure the time it remained visible after exhalation from the mouth. During the experiments, it could be observed with the naked eye that the glycol droplets linger in the air longer than what was captured in the recordings. Not all the droplets were visible with the camera. The recordings showed that with open windows and door (natural ventilation), the droplets travelled the furthest distance (1.8 m) and stayed the longest in the air, while with mixing and natural ventilation, the droplets travelled the shortest (0.5 m) and stayed the least time in the air. These findings confirm that mechanical mixing ventilation increases the removal of aerosols in the air. It is concluded that the portable fog generator system provides a quick method in understanding the duration and distance droplets can travel after being exhaled.","Covid-19; SARS-CoV-2; aerosol; respiratory droplets; visualisation; laser; breathing","en","conference paper","TU Delft OPEN Publishing","","","","","","","","","","Indoor Environment","","",""
"uuid:b3e9d6d1-a146-4783-a4ef-8fe08532f138","http://resolver.tudelft.nl/uuid:b3e9d6d1-a146-4783-a4ef-8fe08532f138","Three dimensional internal and near-wall flow features of a structured porous coated cylinder","Arcondoulis, Elias J. G. (Southern University of Science and Technology); Liu, Yu (Southern University of Science and Technology); Yang, Yannian (Southern University of Science and Technology); Ragni, D. (TU Delft Wind Energy); Rubio Carpio, A. (TU Delft Wind Energy); Avallone, F. (TU Delft Wind Energy)","","2022","The application of a porous coating to a cylinder can significantly reduce the vortex shedding tone when placed in a uniform flow. The mechanism of how this porous media attenuates vortex shedding has been studied more in recent years yet it is still not fully understood. Typical porous materials within a certain range of porosity and airflow resistivity, such as metal foam and porous polyurethane, have been studied extensively; however, the fundamental flow mechanisms responsible for vortex shedding attenuation are very difficult to determine. For example, it is nearly impossible to visualize the internal flow field of porous media with a randomized open-cell internal structure. A Structured Porous Coated Cylinder (SPCC) was designed in recent years to alleviate this internal flow field problem, as the SPCC has clear line of sight along the span and radial direction. SPCC variations have been previously studied and shown to reduce the vortex shedding tone of a bare cylinder in a very similar manner as a randomized porous coated cylinder. In this paper, we present a Tomographic Particle Image Velocimetry study of an SPCC tested in a water tunnel, revealing the previously unseen internal and near-wall flow fields of an SPCC. The flow is visualized in the porous layers, revealing complex interaction between the freestream flow field and the porous structure. Using cross-correlation methods within the flow field, we reveal the entrainment of the flow within the porous layers. Furthermore, implementation of Proper Orthogonal Decomposition shows that vortex shedding occurs within the porous layers.","","en","conference paper","","","","","","","","","","","Wind Energy","","",""
"uuid:3f28f42e-96fa-4d82-bdef-883ad5e0ab89","http://resolver.tudelft.nl/uuid:3f28f42e-96fa-4d82-bdef-883ad5e0ab89","Simulation and Verification or Cu@Ag Core-shell Sintered Paste for Power Semiconductor Die-attach Applications","Wang, Xinyue (Fudan University); Zeng, Zejun (Fudan University); Zhang, Jing (Heraeus Materials Technology); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Liu, Pan (Fudan University)","O'Conner, L. (editor)","2022","With the increasing application of wide bandgap materials such as silicon carbide and gallium nitride in power devices, the working temperature of power devices has been pushed further. Therefore, it brings higher requirements for packaging materials. Sintered silver is a widely accepted chip connection material. However, silver suffers from high prices and electromigration. Therefore, a novel sintered material based on silver-copper core-shell structured particles raises the attention of researchers to solve this deficiency. To accelerate the development of new materials and their related processes, a four-sphere model of the silver-coated copper structure is established in this paper. The mathematical relationship between the porosity and thermal conductivity of sintered body and the actual sintering process was preliminarily established through the calculation based on a series of FEM simulations. The model was further validated through experiments. The modeling method and conclusion are utilized for future process adjustment, which is of great significance to accelerate the development, application, and reliability of new packaging materials.","die-attach material; power electronic packaging; simulation; Cu@Ag particles","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","","","Electronic Components, Technology and Materials","","",""
"uuid:55081ccc-c0ff-408b-b3a2-d1854bce1b9b","http://resolver.tudelft.nl/uuid:55081ccc-c0ff-408b-b3a2-d1854bce1b9b","Emotion deep dive for designers: Seven propositions that operationalize emotions in design innovation","Desmet, P.M.A. (TU Delft Human-Centered Design; TU Delft Design Aesthetics); Xue, H. (TU Delft Design Aesthetics); Xin, X (Beijing Normal University); Liu, W.L. (Beijing Normal University)","Markopoulos, Evagelos (editor); Goonetilleke, Ravindra S. (editor); Luximon, Yan (editor)","2022","This paper presents a five-day intense course that teaches “emotion-driven design”
(EDD) to graduate students with a broad variety of disciplinary backgrounds at the
Faculty of Psychology, Beijing Normal University. We introduce seven principles
drawn from design-relevant emotion knowledge that informed the design of the
course’s overall structure, and explain how they guided the development of learning
activities and materials. We envision that this paper will interest design educators
who aspire teaching how to operationalize emotions in creative design processes to
students with little preexisting expertise in (or scientific knowledge about) emotion
psychology.","Design education; Emotion-driven design; Design innovation; Emotion psychology; Psychology design; User experience; Human-design interactions","en","conference paper","","","","","","","","","","Human-Centered Design","Design Aesthetics","","",""
"uuid:5195a292-4d0f-4167-b0a5-cbc6df8d63a5","http://resolver.tudelft.nl/uuid:5195a292-4d0f-4167-b0a5-cbc6df8d63a5","Evolvability degeneration in multi-objective genetic programming for symbolic regression","Liu, D. (Centrum Wiskunde & Informatica (CWI)); Virgolin, Marco (Centrum Wiskunde & Informatica (CWI)); Alderliesten, T. (Leiden University Medical Center); Bosman, P.A.N. (TU Delft Algorithmics; Centrum Wiskunde & Informatica (CWI))","","2022","Genetic programming (GP) is one of the best approaches today to discover symbolic regression models. To find models that trade off accuracy and complexity, the non-dominated sorting genetic algorithm II (NSGA-II) is widely used. Unfortunately, it has been shown that NSGA-II can be inefficient: in early generations, low-complexity models over-replicate and take over most of the population. Consequently, studies have proposed different approaches to promote diversity. Here, we study the root of this problem, in order to design a superior approach. We find that the over-replication of low complexity-models is due to a lack of evolvability, i.e., the inability to produce offspring with improved accuracy. We therefore extend NSGA-II to track, over time, the evolvability of models of different levels of complexity. With this information, we limit how many models of each complexity level are allowed to survive the generation. We compare this new version of NSGA-II, evoNSGA-II, with the use of seven existing multi-objective GP approaches on ten widely-used data sets, and find that evoNSGA-II is equal or superior to using these approaches in almost all comparisons. Furthermore, our results confirm that evoNSGA-II behaves as intended: models that are more evolvable form the majority of the population. Code: https://github.com/dzhliu/evoNSGA-II","evolvability; genetic programming; multi-objective optimization; Symbolic regression","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Algorithmics","","",""
"uuid:0d12bcd8-cae2-4836-95b9-f50bc8abd404","http://resolver.tudelft.nl/uuid:0d12bcd8-cae2-4836-95b9-f50bc8abd404","A Comparative Study of Deep Reinforcement Learning-based Transferable Energy Management Strategies for Hybrid Electric Vehicles","Xu, Jingyi (Beijing Institute of Technology); Li, Z. (TU Delft Transport and Planning; Beijing Institute of Technology); Gao, Li (Beijing Institute of Technology); Ma, Junyi (Beijing Institute of Technology); Liu, Qi (Beijing Institute of Technology); Zhao, Yanan (Beijing Institute of Technology)","","2022","The deep reinforcement learning-based energy management strategies (EMS) have become a promising solution for hybrid electric vehicles (HEVs). When driving cycles are changed, the neural network will be retrained, which is a time-consuming and laborious task. A more efficient way of choosing EMS is to combine deep reinforcement learning (DRL) with transfer learning, which can transfer knowledge of one domain to the other new domain, making the network of the new domain reach convergence values quickly. Different exploration methods of DRL, including adding action space noise and parameter space noise, are compared against each other in the transfer learning process in this work. Results indicate that the network added parameter space noise is more stable and faster convergent than the others. In conclusion, the best exploration method for transferable EMS is to add noise in the parameter space, while the combination of action space noise and parameter space noise generally performs poorly. Our code is available at https://github.com/BIT-XJY/RL-based-Transferable-EMS.git.","","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","","","Transport and Planning","","",""
"uuid:e438cca0-245c-4bb0-8f5b-4055b186752b","http://resolver.tudelft.nl/uuid:e438cca0-245c-4bb0-8f5b-4055b186752b","A 200Gb/s PAM-4 Transmitter with Hybrid Sub-Sampling PLL in 28nm CMOS Technology","Wang, Zhongkai (University of California); Choi, Minsoo (Samsung Semiconductor); Kwon, Paul (University of California); Lee, Kyoungtae (University of California); Yin, Bozhi (University of California); Liu, Zhaokai (University of California); Park, Kwanseo (University of California); Biswas, Ayan (University of California); Du, S. (TU Delft Electronic Instrumentation)","","2022","This paper presents a complete 200Gb/s PAM-4 transmitter (TX) in 28nm CMOS technology. The transmitter features a hybrid sub-sampling PLL (SSPLL) with a delta-sigma (?S) modulator, clock distribution network with flexible timing control, and data path with a hybrid 5-tap Feed-Forward Equalizer (FFE) and T-coil for bandwidth extension. The prototype chip achieves 4.69 pJ/bit efficiency, 54mV eye height, 0.27UI eye width, and 97% RLM under -6dB channel loss at 50GHz.","28nm; CMOS; SerDes; Sub-sampling PLL; Transmitter","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Electronic Instrumentation","","",""
"uuid:d1436cb5-1496-4f0f-adab-c84b2862162e","http://resolver.tudelft.nl/uuid:d1436cb5-1496-4f0f-adab-c84b2862162e","An Alternative Micro LED Mass Transfer Technology: Self-Assembly","Ji, Liangzheng (Fudan University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Zhang, Jing (Heraeus Materials Technology); Liu, Pan (Fudan University)","","2022","Micro LED display technology has been spotlighted as the most promising technology compared to LCD and OLED. Its excellent advantages include higher brightness, self-illumination, higher resolution, lower power consumption, faster response, higher integration, higher stability, thinner thickness, longer life, etc. In terms of the unique benefits, it is attracting increasing attention from industries. With the commercialization of Micro LED technology, the following hurdles are identified: wafer manufacturing, full color, bonding, and mass transfer. Among them, mass transfer is so far considered as the most severe bottleneck. Several mass transfer technologies have emerged, including fine picking and placing, roll printing, laser transferring, and fluid self-assembly, which aim to solve the mass transfer problems. However, the aforementioned first 3 types of technologies still rely on the pick-and-place process, which is limited when the Micro LED die dimension shrinks to smaller scales due to processability and equipment precision. Fluidity self-assembly, on the other hand, will not be constrained by the Micro LED size and machine accuracy in the mass transfer process, which received increasing attention from researchers. In the self-assembly of component level, gravitational attraction, magnetic /electromagnetic fields, and capillary force are considered the mainstream force to facilitate the assembly process. Therefore, the component self-assembly becomes a prospective substitute for the Micro LED mass transfer solution, which overcomes the problems of the trade-off between throughput and the placement accuracy of the pick-and-place technology.","Micro LED; Mass transfer; Pick-and-place; Selfassembly","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","","","Electronic Components, Technology and Materials","","",""
"uuid:f53ead41-a958-458f-8cbc-3e0097001d5b","http://resolver.tudelft.nl/uuid:f53ead41-a958-458f-8cbc-3e0097001d5b","Finite Element Modeling for Thermal Conductivity of Cement-based Encapsulation Materials","Gao, Hanyan (Fudan University); Zhang, Jing (Heraeus Materials Technology); Zhu, Yingcan (University of Southern Queensland); Guo, Ruiqian (Fudan University); Zhang, Wanlu (Fudan University); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Liu, Pan (Fudan University; Research Institute of Fudan University, Ningbo; Yiwu Research Instiute of Fudan)","","2022","With the trend of miniaturization and the increasing power density, the operating temperature of electronic devices keeps climbing, especially for wide band-gap semiconductors such as silicon carbide and gallium nitride. The high operating temperature up to 250℃ brings challenges to encapsulation materials since traditional encapsulation materials such as epoxy resins and silicone gels hardly bear temperatures above 200℃. Calcium aluminate cement (CAC) was proved to be a promising encapsulation material, which owns high thermal stability with its operating temperature of up to 300℃. Based on its satisfied thermal stability and low cost, the thermal conductivity of CAC was researched in this work with different ratios of 10-μm-sphere-Alumina (Al 2 O 3 ) fillers at different temperatures, which formed μm-scale CAC-Al 2 O 3 composites. In this work, we focused on the thermal conductivity of CAC-Al 2 O 3 composites aiming for encapsulation applications in power electronics packaging. The thermal conductivities of μm-scale CAC-Al 2 O 3 composites by the laser-flash method from room temperature to 350℃ were firstly measured. Results showed with an increasing content of fillers, the TC of CACAl 2 O 3 will increase accordinglyIt also illustrated that calcium aluminate cement was a high thermal stable encapsulation material with thermal conductivity over epoxy resins. Then, the Finite Element Model (FEM) was established and calibrated by experimental data for thermal conductivity simulation. The FEM model accuracy reached 90%. Such models for new filler materials are effective to minimize material development by actual experiments and characterizations, for CAC composite with different fillers. It also provides an alternative method in predicting other physical properties of composites such as coefficient of thermal expansion, porosity, etc.","Encapsulation; Finite element modeling; Cement; Thermal conductivity; Electronic packaging","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","","","Electronic Components, Technology and Materials","","",""
"uuid:00c0c0b4-78e2-4c89-a351-79cba207f056","http://resolver.tudelft.nl/uuid:00c0c0b4-78e2-4c89-a351-79cba207f056","Review of Laser Sintering of Nanosilver Pastes for Die Attachment: Technologies and Trends","Chen, Haixue (Fudan University); Zhang, Jing (Heraeus Materials Technology); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Liu, Pan (Fudan University; Research Institute of Fudan University, Ningbo)","","2022","Nanosilver pastes have been regarded as the most promising die-attach materials for high-temperature and high-power applications due to their advantages such as excellent thermal conductivity, electrical conductivity, high temperature resistance, and good shear strength. However, the common hot pressing sintering process for nanosilver pastes has the limitations of long sintering time and complicated sintering processes. Thus, laser sintering has been proposed as a rapid sintering method that attracts increasing interest due to its advantages of high energy density, fast temperature rise, easy densification, etc. In this review, the recent advances in laser sintering processes were summarized, including pressure laser sintering, backside sintering, and hybrid bimodal laser sintering. The effects of various laser sintering process parameters on joint performance, such as laser power, sintering pressure, irradiation time, and defocusing amount, were further discussed. The rapid sintering mechanism of laser sintering silver nanoparticles(AgNPs) was revealed, while microscopic explanations need to be further explored. This review provided ideas and methods for subsequent researchers to develop rapid sintering methods for power electronic packaging.","Nanosilver; Laser sintering; Die Attachment","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","","","Electronic Components, Technology and Materials","","",""
"uuid:005b3281-eb9d-44ce-9e66-ad37e4931dd6","http://resolver.tudelft.nl/uuid:005b3281-eb9d-44ce-9e66-ad37e4931dd6","A TCAD Simulation Study on the Short-circuit Performance of 650V P-pillar Offset Super-junction MOSFET","Yuan, Wucheng (Southern University of Science and Technology); Liu, Ke (Southern University of Science and Technology); Wang, S. (TU Delft Bio-Electronics); Tan, C. (TU Delft Electronic Components, Technology and Materials); Ye, H. (Southern University of Science and Technology)","","2022","The limitation of Silicon based power MOSFET was broken by the super-junction (SJ) structure, which can provide lower specific on-resistance and higher breakdown voltage compared with the conventional power MOSFET structure. Multi-epitaxial and multi-ion-implant technology, as a mature manufacturing process of the SJ structure, has been widely used in the field of SJ-MOSFET. Therefore, this process is applied to construct the cell structure of 650V SJ-MOSFET in our study. Based on practical application, high current caused by unexpected short circuit will induce an increasing of the internal temperature of SJ-MOSFET, which leads to an irreversible damage in the SJ-MOSFET devices. However, the short-circuit robustness of SJ-MOSFET is still unstable, and the structure needs to be further improved. In our study, the electrical performance of a 650V SJ-MOSFET with offset P-pillar is theoretically investigated by means of technology computer aided design (TCAD) when the SJ-MOSFET is short circuited. The results clearly show that the optimized SJ-MOSFET can withstand the source-drain voltage of 400V for at least 10 μs in the case of the short-circuit. The thermal distribution and peak temperature of the cell structure of SJ-MOSFET are also simulated to assist in the analysis of the short circuit capable of the device. In addition, the hole current density distribution of two SJ-MOSFETs is considered to gain insight into the effect of P-pillar parameters on the short-circuit robustness. The result represents that the structure with offset P-pillar can effectively improve the short-circuit capability.","Super-junction structure; Short circuit; P-pillar offset; TCAD simulation","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","","","Bio-Electronics","","",""
"uuid:5b98065c-8069-4933-8f9e-147edb367f80","http://resolver.tudelft.nl/uuid:5b98065c-8069-4933-8f9e-147edb367f80","Study on Reverse Recovery of a P-pillar Tunable Super-Junction MOSFET*","Liu, Ke (Southern University of Science and Technology); Yuan, Wucheng (Southern University of Science and Technology); Wang, S. (TU Delft Bio-Electronics); Tan, C. (TU Delft Electronic Components, Technology and Materials); Ye, H. (TU Delft Electronic Components, Technology and Materials; Southern University of Science and Technology)","","2022","In this paper, a novel bubble-shift super junction (SJ) MOSFET structure is proposed, and its main static electrical parameters and reverse recovery characteristics are simulated by TCAD software tool. By designing the P-pillar ion implantation windows with a certain offset, the bubble-shift SJ-MOSFET contains a curved pillar region in the upper half of the P-pillar. In the reverse recovery test of the proposed bubble-shift SJ-MOSFET, the peak reverse recovery current (I rrm ) is reduced from 16.04 A to 15.21 A, and the current drop rate (di/dt) is reduced from 1587 A/μs to 815 A/μs. Correspondingly, the proposed device achieves a better reverse recovery characteristic while sacrificing a small fraction of the drain-source breakdown voltage (BV) and drain-source special on-resistance (R on,sp ). Compared with the BV of 700 V and the R on,sp of 9 mΩ·cm 2 of the benchmark SJ-MOSFET. The proposed device has a BV of 650 V and a R on,sp of 12.4 mΩ·cm 2 . Mechanistically, the non-uniform depletion of the curved P-pillar reduces the carrier extraction rate, thereby prolonging the reverse current drop time (t f ) and increasing the softness factor (S) of the bubble-shift SJ-MOSFET.","super junction; reverse recovery; P-pillar; bubbleshift; TCAD","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","","","Bio-Electronics","","",""
"uuid:408ac6ca-f0dc-4d79-abbf-618cdea1c78f","http://resolver.tudelft.nl/uuid:408ac6ca-f0dc-4d79-abbf-618cdea1c78f","Bonding Process of Copper Foam-Silver Composite and Performance Characterization of the Joint","Lv, Guoping (Guilin University of Electronic Technology); Yan, Haidong (Zhejiang University); Yan, Haidong (Guilin University of Electronic Technology); Yang, Daoguo (Guilin University of Electronic Technology); Wu, Xinke (Zhejiang University); Sheng, Kuang (Zhejiang University); Liu, Chaohui (National New Energy Vehicle Technology Innovation); Zhang, Yakun (National New Energy Vehicle Technology Innovation); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2022","As a key heat-dissipating and electrical interconnecting component in high-temperature power modules, die-attach and substrate-attach layers play an important role in effectively reducing the thermal resistance and improving the long-term reliability. Traditional substrate-attach materials limit the high-temperature applications of packaging modules due to their high thermal resistance and high-temperature reliability. To solve the above deficiency, a copper foam-silver composite was proposed in this paper, which was prepared by mixing copper foam solid skeleton with micron silver paste. According to the results of thermogravimetric analysis (TGA) of silver paste, the preheating process was determined and sintered at 270°C and 10MPa. The influence of different preparation technology on the quality of sintered joint was investigated. The morphology characteristics and distribution of sintered silver in the copper foam were observed by scanning electron microscope (SEM). The results show that the sintered silver of group C samples can be uniformly filled into the solid skeleton of copper foam, and the densification degree is high, without cracks, delamination, and holes. The shear strength can reach 55MPa.","large-area bonding; copper foam-Ag composite film; preparation process","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","","","Electronic Components, Technology and Materials","","",""
"uuid:d870e2f8-78ae-43d5-bef2-351fb755d8d6","http://resolver.tudelft.nl/uuid:d870e2f8-78ae-43d5-bef2-351fb755d8d6","Research on Thermal-Mechanical Properties of GaN Power Module Based on QFN Package by Using Nano Copper/Silver Sinter Paste","Li, Shizhen (Southern University of Science and Technology); Liu, X. (TU Delft Electronic Components, Technology and Materials); Fan, Jiajie (Fudan University); Tan, C. (TU Delft Electronic Components, Technology and Materials); Wang, S. (TU Delft Bio-Electronics); Xie, Bin (Hong Kong Applied Science and Technology Research Institute); Ye, H. (Southern University of Science and Technology)","","2022","The wide-bandgap semiconductors represented by GaN have a broad application prospect because of their high service temperature and high switch frequency. Quad-Flat-No-Lead (QFN) Package is currently one of the mainstream packaging methods due to its low cost and high efficiency. However, the low reliability of QFN used in GaN devices is still a crucial problem caused by elevated temperatures and the thermal stress induced by the mismatch of coefficient of thermal expansion (CTE). Therefore, it is necessary to control the temperature inner the package and increase the mechanical property of the bonding layer. In this paper, the finite element method (FEM) with thermal-mechanical coupling is performed to optimize the reliability of the bonding layer by adopting sinter nano Cu and silver. Based on the conventional QFN package module, we tried to add different metallization on the bonding surface to decrease the influence of CTE mismatch. We should note that the Anand viscoplastic model was used in the materials of Sintered Ag and lead-free solder paste presented by SAC305, which were the most commonly used in die-attachment. The results showed that the utilization of nano copper/silver paste could hardly facilitate thermal performance although sintered Ag had excellent thermal conductivity. Since the Anand modules of Ag and SAC305 were different, there were some impacts on the stress distribution and deformation. During the bonding process, a large thermal stress generated between die-attachment layer and Package or the PCB. The die-attachment layer formed by nano Ag paste suffered the smaller thermal stress because its CTE is comparable to that of thermal pad. In terms of sintered Ag, the bonding layer generated more elastic strain. As the deformation recovered to initial stage, the stress decreased because of the elastic strain. And we also found that the Ag metallization could decreased the maximum stress of model at heating stage. But Ag metallization suffered larger thermal stress as the temperature decreased. The selection of connection materials and metallization are a crucial part of design the structure of electronic package. And this paper could provide a reference for optimize the package structure to further improve their reliability in future works.","GaN; QFN; simulation; sintered Ag; thermal stress","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","","","Electronic Components, Technology and Materials","","",""
"uuid:ddbcfa30-6322-4b50-aad3-d61e386e5eec","http://resolver.tudelft.nl/uuid:ddbcfa30-6322-4b50-aad3-d61e386e5eec","Finite Element Analysis of Power Module Packages with One-step Molding for Power Inductors","Li, Xiao (Fudan University); Tang, Jiuyang (Fudan University); Zhao, Jiayan (Mazo Technology Company Limited); Li, Jinbing (Mazo Technology Company Limited); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Liu, Pan (Fudan University)","","2022","With the development of 5G communication technology and the rise of power semiconductors, the switching frequency of the circuit keeps increasing, which pushes for miniaturization of power modules and related components. Therefore, in this paper, a one-step molding technology was proposed for a DC/DC buck converter power module. We proposed a method of using Soft Magnetic Powder filled Epoxy (SMPE) adhesive as a molding material to encapsulate a power module, which is a DC/DC buck converter power module contains several passive components, 1 power inductor, and a high-efficiency switching regulator with two integrated N-channel MOSFETs. On the basis of Finite Element Method (FEM), models were firstly established with component level moldings and checked with actual module samples for calibration. Based on the calibrated model, inductors without component level molding were then simulated. SMPE with 4~7μm insulated carbonyl ferrous powder were prepared and measured the magnetic relative permeability. Such material was investigated to pot the whole power module as a one-step molding, instead of separate molding for the power inductor and the power module. After that, thermal analysis and inductance were calculated and compared.","Finite element simulation; Power module packaging; Relative Permeability; Thermal management","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","","","Electronic Components, Technology and Materials","","",""
"uuid:03567474-815f-4139-8e92-7de9f3018704","http://resolver.tudelft.nl/uuid:03567474-815f-4139-8e92-7de9f3018704","Graph Convolution-Based Deep Reinforcement Learning for Multi-Agent Decision-Making in Interactive Traffic Scenarios","Liu, Qi (Beijing Institute of Technology); Li, Z. (TU Delft Transport and Planning); Li, Xueyuan (Beijing Institute of Technology); Wu, Jingda (Nanyang Technological University); Yuan, Shihua (Beijing Institute of Technology)","","2022","A reliable multi-agent decision-making system is highly demanded for safe and efficient operations of connected and autonomous vehicles (CAVs). In order to represent the mutual effects between vehicles and model the dynamic traffic environments, this research proposes an integrated and open-source framework to realize different Graph Reinforcement Learning (GRL) methods for better decision-making in interactive driving scenarios. Firstly, an interactive driving scenario on the highway with two ramps is constructed. The vehicles in this scenario are modeled by graph representation, and features are extracted via Graph Neural Network (GNN). Secondly, several GRL approaches are implemented and compared in detail. Finally, The simulation in the SUMO platform is carried out to evaluate the performance of different G RL approaches. Results are analyzed from multiple perspectives to compare the performance of different G RL methods in intelligent transportation scenarios. Experiments show that the implementation of GNN can well model the interactions between vehicles, and the proposed framework can improve the overall performance of multi-agent decision-making. The source code of our work can be found at https://github.com/Jacklinkk/TorchGRL.","","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","","","Transport and Planning","","",""
"uuid:1dec8ae3-f12e-4cfe-b3b0-5932eb39f2ed","http://resolver.tudelft.nl/uuid:1dec8ae3-f12e-4cfe-b3b0-5932eb39f2ed","LQR Optimal Control of Four-steering Vehicle Based on Particle Swarm Optimization Algorithm","Zhu, Songfeng (Beijing Institute of Technology); Li, Xueyuan (Beijing Institute of Technology); Qu, Xinyi (Inner Mongolia First Machinery Group); Liu, Qi (Beijing Institute of Technology); Li, Z. (TU Delft Transport and Planning; Beijing Institute of Technology)","","2022","This paper proposes a linear quadratic controller based on particle swarm algorithm for the rear wheel control of four-wheel steering vehicle. Particle swarm optimization with fitness functions is used to optimize the coefficients of the weight matrix offline. The fuzzy rules following the controller is used if the road condition is terrible. The simulation results show that the LQR control model based on particle swarm optimization makes the trajectory tracking of the vehicle better and the side slip angle of the vehicle lower. It can be proved that the controller has positive effect on handling stability of the vehicle and safety of drivers.","fuzzy controller; LQR; particle swarm optimization; side slip angle","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","","","Transport and Planning","","",""
"uuid:248b2da3-cea9-4fb1-8266-4e987c6a5140","http://resolver.tudelft.nl/uuid:248b2da3-cea9-4fb1-8266-4e987c6a5140","Doplor Sleep: Monitoring Hospital Soundscapes for Better Sleep Hygiene","Ozcan Vieira, E. (TU Delft Design Aesthetics); Liu, Y. (Student TU Delft); Vroon, Jered (TU Delft Internet of Things); Kamphuis, Daan (Reinier de Graaf Gasthuis); Spagnol, S. (TU Delft Design Aesthetics)","","2022","Good sleep is conducive to the recovery process of hospital patients - and yet, in many wards, sleep duration and quality can often be suboptimal, in part due to modifiable hospital-related sounds and noises. At the neurological ward of the Reinier de Graaf hospital in Delft, the Netherlands, we developed and evaluated a prototype information exchange system to raise awareness of specific sounds as disturbing patients' sleep. The system both classifies different relevant sound events and tracks sleep quality (using a Fitbit device). This information is then visualized for patients and staff to present the influence of the soundscape on patients' sleep hygiene in a friendly and comprehensive way. We discuss the design process, including a context study and various evaluations of the technology, interface, and created affordances. Our initial findings indicate that visualizing hospital soundscapes may, indeed, support both patients and staff in their efforts towards better sleep hygiene.","data visualization; design for healthcare; Sound-driven design","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Design Aesthetics","","",""
"uuid:4fba194c-76b3-4c8b-bd3d-ba0279e9726d","http://resolver.tudelft.nl/uuid:4fba194c-76b3-4c8b-bd3d-ba0279e9726d","Comparative Analysis of a Detailed and an Average VARC DCCB model in MTDC Systems","Shetgaonkar, A.D. (TU Delft Intelligent Electrical Power Grids); Liu, Siyuan (Xian Jiaotong University); Popov, M. (TU Delft Intelligent Electrical Power Grids)","","2022","Direct current circuit breaker (DC CB) is the key component to provide reliable operation of Multi-terminal Direct Current (MTDC) system. Fast, effective and accurate DC CB models are needed for system-level studies. Due to large number of components in the DC CB, its detailed modeling is needed in order to simulate current interruption process correctly. However, the simulation time may be longer depending on the network complexity. This paper proposes an average model which is compared to a detailed model of a Voltage-source-converter resonant current (VARC) DC CB in an MTDC system in terms of its performance and computation time for two typical simulation cases. The average and the detailed model are modelled and simulated in PSCAD/EMTDC environment. An accurate response of the average model during fast transient event is presented, showing additional computational advantage.","Average model; VARC DC circuit breaker; HVDC; MTDC","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.","","2023-04-27","","","Intelligent Electrical Power Grids","","",""
"uuid:3d95605c-de1c-4ed6-88ff-0ca0fc68c6f4","http://resolver.tudelft.nl/uuid:3d95605c-de1c-4ed6-88ff-0ca0fc68c6f4","Experimental and numerical validation of an inter-ply friction model for thermoset based fibre metal laminate under hot-pressing conditions","Liu, S. (TU Delft Aerospace Manufacturing Technologies); Sinke, J. (TU Delft Aerospace Manufacturing Technologies); Dransfeld, C.A. (TU Delft Aerospace Manufacturing Technologies)","Vassilopoulos, Anastasios P. (editor); Michaud, Véronique (editor)","2022","Hot-pressing can be an attractive fabrication method that enables the forming of hybrid materials like thermoset based fibre metal laminates. However, the process simulation on press forming requires accurate material characterization and boundary conditions to facilitate part design for a defect-free component. In order to improve the overall predictive simulation quality, the inter-ply sliding at metal-prepreg interfaces which is one of the critical deformation mechanisms is considered. An inter-ply friction model has been established using an experimental friction test apparatus and the effect of slip rate, normal force and temperature is taken into consideration. To validate the proposed friction model, a comparative study between results obtained from the numerical model and the experimental ones is carried out. The research demonstrates that the inter-ply friction model can be a valuable building block for the finite element simulation of the hot-pressing process for thermoset based fibre metal laminates.","Fibre metal laminates (FMLs); Inter-ply friction; Hot-pressing; Numerical simulation","en","conference paper","EPFL Lausanne, Composite Construction Laboratory","","","","","","","","","","Aerospace Manufacturing Technologies","","",""
"uuid:1a458777-00fe-4ae0-b09a-f2b2ac9a80c0","http://resolver.tudelft.nl/uuid:1a458777-00fe-4ae0-b09a-f2b2ac9a80c0","Embedding Adaptive Features in the ArduPilot Control Architecture for Unmanned Aerial Vehicles","Li, Peng (Southeast University); Liu, Di (Technische Universität München; Southeast University); Xia, Xin (Southeast University); Baldi, S. (TU Delft Team Bart De Schutter; Southeast University)","","2022","The operation of Unmanned Aerial Vehicles (UAVs) is often subject to state-dependent alterations and unstructured uncertainty factors, such as unmodelled dynamics, environmental weather disturbances, aerodynamics gradients, or changes in inertia and mass due to payloads. While a large number of autopilot solutions have been proposed to operate UAVs, none of these solutions is able to counteract the effects of state-dependent and unstructured uncertainties online by parameter estimation and adaptive control techniques. This work presents a systematic integration of adaptive control into ArduPilot, a popular open-source autopilot suite maintained by a large community of UAV developers. Adaptation features are embedded in the ArduPilot control structure without altering the original architecture, to allow users to use the autopilot suite as usual. Tests show that the proposed adaptive ArduPilot provides consistent improved performance in several uncertain flight conditions. The source code of the proposed adaptive ArduPilot is released at https://github.com/Friend-Peng/Adaptive-ArduPilot-Autopilot.","Uncertainty; Systematics; Parameter estimation; Source coding; Autonomous aerial vehicles; Aerodynamics; Autopilot","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.","","2023-07-10","","","Team Bart De Schutter","","",""
"uuid:955e1492-4f5a-4782-8042-cf0961ae9289","http://resolver.tudelft.nl/uuid:955e1492-4f5a-4782-8042-cf0961ae9289","An Economic Model Predictive Control Approach for Load Mitigation on Multiple Tower Locations of Wind Turbines","Feng, Z. (TU Delft Team Riccardo Ferrari); Gallo, A.J. (TU Delft Team Riccardo Ferrari); Liu, Y. (TU Delft Team Riccardo Ferrari); Pamososuryo, A.K. (TU Delft Team Jan-Willem van Wingerden); Ferrari, Riccardo M.G. (TU Delft Team Riccardo Ferrari); van Wingerden, J.W. (TU Delft Team Jan-Willem van Wingerden)","","2022","The current trend in the evolution of wind turbines is to increase their rotor size in order to capture more power. This leads to taller, slender and more flexible towers, which thus experience higher dynamical loads due to the turbine rotation and environmental factors. It is hence compelling to deploy advanced control methods that can dynamically counteract such loads, especially at tower positions that are more prone to develop cracks or corrosion damages. Still, to the best of the authors’ knowledge, little to no attention has been paid in the literature to load mitigation at multiple tower locations. Furthermore, there is a need for control schemes that can balance load reduction with optimization of power production. In this paper, we develop an Economic Model Predictive Control (eMPC) framework to address such needs. First, we develop a linear modal model to account for the tower flexural dynamics. Then we incorporate it into an eMPC framework, where the dynamics of the turbine rotation are expressed in energy terms. This allows us to obtain a convex formulation, that is computationally attractive. Our control law is designed to avoid the ""turn-pike"" behavior and guarantee recursive feasibility. We demonstrate the performance of the proposed controller on a 5MW reference WT model: the results illustrate that the proposed controller is able to reduce the tower loads at multiple locations, without significant effects to the generated power.","Economics; Vibrations; Damping; Computational modeling; Poles and towers; Fatique; Wind turbines","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.","","2023-07-10","","","Team Riccardo Ferrari","","",""
"uuid:e667a7b9-5468-4d83-a805-b0a8a9dbb890","http://resolver.tudelft.nl/uuid:e667a7b9-5468-4d83-a805-b0a8a9dbb890","Low Temperature Sapphire to Silicon Flip Chip Interconnects by Copper Nanoparticle Sintering","Ji, X. (TU Delft Electronic Components, Technology and Materials); van Zeijl, H.W. (TU Delft Electronic Components, Technology and Materials); Romijn, J. (TU Delft Microelectronics); van Ginkel, H.J. (TU Delft Electronic Components, Technology and Materials); Liu, X. (TU Delft Electronic Components, Technology and Materials); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2022","The continuous trend to integrate more multi-functions in a package often involves, Heterogeneous Integration of multi-functional blocks in some kind of 3D stacking. The conventional flip chip for die-on-substrate technology applies solder for integration. However, solder joint integration has the disadvantages of restricting height, reflow issues and re-melting at high operating temperatures. Nanometallic particle sintering offers a potential solution for these solder related issues. Nanometallic particle sintering occurs at low temperature and does not reflow and melt at higher temperatures. Hence, it can be applied for quite precise alignment and integration technologies, such as photonic components on silicon for harsh environment applications. In order to test this concept, we use sapphire and Si wafers with different mechanical properties, which can lead to the coefficient of thermal expansion mismatch. The sapphire chip can operate at a higher temperature applied for ultraviolet photonics application. This report describes a novel approach using copper nanoparticles paste patterned through photolithographic stencil printing. The photoresist acts as the stencil mask, and a photoresist lift-off process is applied to strip the photoresist stencil. This process has the advantages of lithographic form factor and precision and provides a chip to chip interconnect with a standard height of 20 µm.","flip chip; heterogeneous integration; copper nanoparticle; nano Cu bump; low temperature sintering","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","","Microelectronics","Electronic Components, Technology and Materials","","",""
"uuid:a61918b0-4e20-4aca-95bb-f20229f965f7","http://resolver.tudelft.nl/uuid:a61918b0-4e20-4aca-95bb-f20229f965f7","Point clouds and Hydroinformatics","Diaz, Vitali (TU Delft Digital Technologies); Liu, H. (TU Delft GIS Technologie); van Oosterom, P.J.M. (TU Delft Digital Technologies); Meijers, B.M. (TU Delft Digital Technologies); Verbree, E. (TU Delft Digital Technologies); Baart, F. (Deltares); Pronk, M.J. (Deltares); Van Lankveld, T. (Netherlands eScience Center)","","2022","Point cloud is made up of a multitude of three-dimensional (3D) points with one or more attributes attached. Point cloud is the third data paradigm in addition to the well-established object (vector) and gridded (raster) representations, since point cloud data can be directly collected, computed, stored, and analyzed without converting to other types. Modern ways of data acquisition, including laser scanning from airborne, mobile, or static platforms, multi-beam echo-sounding, and dense image matching from photos, generate millions to trillions of 3D points with attached attributes. If the collection is carried out in different periods, one of the essential attributes is precisely time, allowing spatiotemporal analysis to be performed. Its use is widespread in some fields such as metrology and quality inspection, virtual reality, indoor/outdoor navigation, object detection, vegetation monitoring, building modeling, cultural heritage, and diverse visualization applications. There are some examples in fields related to hydroinformatics, mainly related to terrain modeling. Due to its nature of big data, over the past decades, a series of developments have been carried out in the different processing chains for the optimal use of point cloud. This research seeks to introduce the various point cloud developments from which the hydroinformatics community and research could benefit. A review of recent advances is made, mainly including the analysis and visualization of point cloud for dealing with water-related problems. Potential areas of application and development in hydroinformatics are identified. These include, for example, the topics of coastal monitoring, coastal erosion, shallow water assessment, ice sheet change analysis, sea-level rise assessment, monitoring of levels in water bodies, crop and vegetation monitoring, analysis of the effects of groundwater depletion, detail tracing of basins and channels, analysis of floods with detailed terrain models, and drought monitoring in crops and forests. The challenges to overcome and ongoing developments regarding point cloud application in hydroinformatics are also discussed.","","en","conference paper","","","","","","Abstract from EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022","","","","","Digital Technologies","","",""
"uuid:623e0fe9-d07c-471d-8093-7e1d38bf2daa","http://resolver.tudelft.nl/uuid:623e0fe9-d07c-471d-8093-7e1d38bf2daa","A 590 μw, 106.6 dB SNDR, 24 kHz BW Continuous-Time Zoom ADC with a Noise-Shaping 4-bit SAR ADC","Mehrotra, Shubham (NXP Semiconductors; Student TU Delft); Eland, Efraim (Student TU Delft); Karmakar, S. (TU Delft Electronic Instrumentation); Liu, Angqi (Student TU Delft); Gonen, B. (TU Delft Electronic Instrumentation; Ethernovia); Bolatkale, M. (TU Delft Electronic Instrumentation; NXP Semiconductors); Van Veldhoven, Robert (NXP Semiconductors); Makinwa, K.A.A. (TU Delft Microelectronics)","","2022","This paper presents a continuous-Time zoom ADC for audio applications. It combines a 4-bit noise-shaping coarse SAR ADC and a fine delta-sigma modulator with a tail-resistor linearized OTA for improved linearity, energy efficiency, and handling of out-of-band interferers compared to previous designs. In 160 nm CMOS, the prototype chip occupies 0.36 mm2, achieves 107.2 dB SNR, 106.6 dB SNDR, and 107.3 dB dynamic range in a 24 kHz bandwidth while consuming 590 μW from a 1.8 V supply. This translates into a Schreier figure-of-merit (FoMs) of 183.4 dB and a FoMSNDR of 182.7 dB.","A/D conversion; audio analog to digital converter (ADC); continuous-Time delta-sigma ADC; dynamic zoom ADC; high linearity operational transconductance amplifier (OTA); low-power circuits; noise-shaping SAR ADC","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.","","2023-04-24","","Microelectronics","Electronic Instrumentation","","",""
"uuid:96ac8fbe-9fd9-4407-aeac-ea442229702c","http://resolver.tudelft.nl/uuid:96ac8fbe-9fd9-4407-aeac-ea442229702c","Non-Consensus Opinion Model with Byzantine Nodes","Liu, X. (TU Delft Network Architectures and Services); Achterberg, M.A. (TU Delft Network Architectures and Services); Kooij, Robert (TU Delft BUS/TNO STAFF; TU Delft Network Architectures and Services)","Nace, Dritan (editor); Rak, Jacek (editor); Tomaszewski, Artur (editor)","2022","inion dynamics models study how the interaction among people influences the opinion formation process. In most opinion dynamics models, only one opinion can exist in the steady state, which is different from the real-life opinion formation process. In 2009, Shao et at. introduced a Non-Consensus Opinion (NCO) model, which allows different opinions to coexist in the steady state. This paper extends the NCO model by introducing a special type of nodes, namely Byzantine nodes, to play the role of dishonest people. We perform simulations on three different network models: small-scale graphs, Erdős-Rényi random graphs and scale-free networks. We find a new steady state for the NCO model: the cyclic steady state. The cyclic behavior of the NCO and Byzantine NCO model is discussed, including a method to generate networks with extremely long cycle lengths. Other properties of the Byzantine NCO model, such as the probability of cyclic behavior and the final opinion distribution, are also studied. We find that the introduction of Byzantine nodes generally steers towards a more balanced steady state and increases the probability of cyclic behavior. The latter is particularly problematic in communication systems, where the large cycle lengths may cause a very slow consensus process and thus stalling future communications.","Byzantine nodes.; Complex Networks; Opinion models; Social Dynamics model","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.","","2023-05-01","","","Network Architectures and Services","","",""
"uuid:06f907ea-7cbb-46bb-863f-87229532e41c","http://resolver.tudelft.nl/uuid:06f907ea-7cbb-46bb-863f-87229532e41c","A Ring-Oscillator Sub-Sampling PLL With Hybrid Loop Using Generator-Based Design Flow","Wang, Zhongkai (University of California); Choi, Minsoo (Samsung Semiconductor); Wright, John (University of California); Lee, Kyoungtae (University of California); Liu, Zhaokai (University of California); Yin, Bozhi (University of California); Han, Jaeduk (Hanyang University); Du, S. (TU Delft Electronic Instrumentation); Alon, Elad (University of California)","","2022","We present a ring-oscillator-based sub-sampling phase-locked loop (PLL) using a generator-based design flow. A hybrid loop with a delta-sigma ($\Delta \Sigma$) modulator is applied to reduce the loop filter (LF) area and the control ripple. The generator automatically produces the ring oscillator and PLL to meet the provided specifications. The 10-GHz PLL instance implemented in 28-nm planar process achieves RMS jitter of}299.5 fs and power of 9.9 mW from a 1-V supply.","PLL; sub-sampling; ring oscillator; hybrid; PLL generator","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","","","Electronic Instrumentation","","",""
"uuid:52e4a923-eb7e-421e-9544-70457e362d04","http://resolver.tudelft.nl/uuid:52e4a923-eb7e-421e-9544-70457e362d04","A 5GS/s 360MHz-BW 68dB-DR Continuous-Time 1-1-1 Filtering MASH ΔΣ ADC in 40nm CMOS","Liu, Qilong (Eindhoven University of Technology; NXP Semiconductors); Breems, Lucien (Eindhoven University of Technology; NXP Semiconductors); Zhang, Chenming (Eindhoven University of Technology; NXP Semiconductors); Bajoria, Shagun (Eindhoven University of Technology; NXP Semiconductors); Bolatkale, M. (TU Delft Electronic Instrumentation; NXP Semiconductors); Rutten, Robert (NXP Semiconductors); Radulov, Georgi (Eindhoven University of Technology)","","2022","In the pursuit of ever larger bandwidths, in recent years GHz-rate continuous-time (CT) oversampled ADCs have been reported in literature that achieve bandwidths of hundreds of MHz and have even exceeded the GHz barrier [1]-[3]. As impressive as these bandwidths are for CT ADCs, the required ADC architectures are complex, are sensitive to layout parasitics due to the high sampling rates, and most important of all, are power hungry, consuming several hundreds of mW. In this paper, we propose a filtering rnulti-stage noise-shaping (MASH) ΔΣ ADC architecture that overcomes the abovementioned drawbacks. Passive delay compensating filters [4] are used to realize broadband and deep suppression of the input signal component at the internal filter nodes of the ADC. As a result, no interstage DACs are needed, which are commonly required to generate the quantization error replicas in a MASH ΔΣ ADC, saving substantial power and greatly reducing the parasitic load of the high-speed critical nodes. Moreover, because of the absence of signal content at the internal filter nodes, the backend stages of the MASH architecture have relaxed linearity requirements and can be implemented with simple low-power Gm-C filters. Precise excess loop delay and excess phase compensation are accomplished with a partly resistive and capacitive stabilization DAC, enabling very-high-speed operation of the ΔΣ loops. The realized MASH ADC is sampled at 5GHz and achieves 68dB/65dB DR/peak SNDR over a 360MHz bandwidth, -78dBc THD at -1dBFS for a 115MHz input signal, and consumes 158mW. Implemented in a mature 40nm CMOS technology, the ADC occupies only 0.21 mm2 core area, achieves 2× lower power, 5dB higher Schreier FOM and 2× lower Walden FOM compared to state-of-the-art broadband CT ADCs in advanced 16nm-28nm nodes [1]-[3].","","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Electronic Instrumentation","","",""
"uuid:710d628c-8363-41e6-b1f7-fe32341d271d","http://resolver.tudelft.nl/uuid:710d628c-8363-41e6-b1f7-fe32341d271d","An Ensemble Learning Framework for Vehicle Trajectory Prediction in Interactive Scenarios","Li, Z. (TU Delft Transport and Planning; Beijing Institute of Technology); Lin, Yunlong (Beijing Institute of Technology); Cheng, Gong (Beijing Institute of Technology); Wang, X. (TU Delft Transport and Planning); Liu, Qi (Beijing Institute of Technology); Gong, Jianwei (Beijing Institute of Technology); Lu, Chao (Beijing Institute of Technology)","","2022","Precisely modeling interactions and accurately predicting trajectories of surrounding vehicles are essential to the decision-making and path-planning of intelligent vehicles. This paper proposes a novel framework based on ensemble learning to improve the performance of trajectory predictions in interactive scenarios. The framework is termed Interactive Ensemble Trajectory Predictor (IETP). IETP assembles interaction-aware trajectory predictors as base learners to build an ensemble learner. Firstly, each base learner in IETP observes historical trajectories of vehicles in the scene. Then each base learner handles interactions between vehicles to predict trajectories. Finally, an ensemble learner is built to predict trajectories by applying two ensemble strategies on the predictions from all base learners. Predictions generated by the ensemble learner are final outputs of IETP. In this study, three experiments using different data are conducted based on the NGSIM dataset. Experimental results show that IETP improves the predicting accuracy and decreases the variance of errors compared to base learners. In addition, IETP exceeds baseline models with 50% of the training data, indicating that IETP is data-efficient. Moreover, the implementation of IETP is publicly available at https://github.com/BIT-Jack/IETP.","","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","","","Transport and Planning","","",""
"uuid:9864c313-2e8a-4521-a624-dc956ef615fd","http://resolver.tudelft.nl/uuid:9864c313-2e8a-4521-a624-dc956ef615fd","EdgeTuner: Fast Scheduling Algorithm Tuning for Dynamic Edge-Cloud Workloads and Resources","Han, Rui (Beijing Institute of Technology); Wen, Shilin (Beijing Institute of Technology); Liu, Chi Harold; Yuan, Ye (Beijing Institute of Technology); Wang, Guoren (Beijing Institute of Technology); Chen, Lydia Y. (TU Delft Data-Intensive Systems)","","2022","Edge-cloud jobs are rapidly prevailing in many application domains, posing the challenge of using both resource-strenuous edge devices and elastic cloud resources. Efficient resource allocation on such jobs via scheduling algorithms is essential to guarantee their performance, e.g. latency. Deep reinforcement learning (DRL) is increasingly adopted to make scheduling decisions but faces the conundrum of achieving high rewards at a low training overhead. It is unknown if such a DRL can be applied to timely tune the scheduling algorithms that are adopted in response to fast changing workloads and resources. In this paper, we propose EdgeTuner to effectively leverage DRL to select scheduling algorithms online for edge-cloud jobs. The enabling features of EdgeTuner are sophisticated DRL model that captures complex dynamics of Edge-Cloud jobs/tasks and an effective simulator to emulate the response times of short-running jobs in accordance to dynamically changing scheduling algorithms. EdgeTuner trains DRL agents offline by directly interacting with the simulator. We implement EdgeTuner on Kubernetes scheduler and extensively evaluate it on Kubernetes cluster testbed driven by the production traces. Our results show that EdgeTuner outperforms prevailing scheduling algorithms by achieving significant lower job response time while accelerating DRL training speed by more than 180x.","DRL; Edge-cloud workloads; Kubernetes; run-time tuning; scheduling algorithm","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Data-Intensive Systems","","",""
"uuid:c75f864b-814f-4f8d-b749-0b503906af15","http://resolver.tudelft.nl/uuid:c75f864b-814f-4f8d-b749-0b503906af15","Quantifying the Uncertainty of Short-Term Vegetation Anomalies Detection Using Eo-Based Coarse-Resolution Vegetation Products","Zhou, J. (TU Delft Optical and Laser Remote Sensing; Central China Normal University; Key Laboratory for Geographical Process Analysis & Simulation of Hubei Province, Wuhan); Liu, Xuan (Central China Normal University; Key Laboratory for Geographical Process Analysis & Simulation of Hubei Province, Wuhan); Xiong, Xuqian (Central China Normal University; Key Laboratory for Geographical Process Analysis & Simulation of Hubei Province, Wuhan); Jia, Li (Chinese Academy of Sciences); Lu, Jing (Chinese Academy of Sciences); Cui, Yilin (Central China Normal University; Key Laboratory for Geographical Process Analysis & Simulation of Hubei Province, Wuhan)","","2022","Satellite-based Earth Observation systems archived a variety of vegetation products during the last 50 years, which can reveal regional to global ecosystem dynamics across diverse spatiotemporal scales. The anomaly metrics such as Vegetation Condition Index (VCI) defined by comparing the current vegetation growth condition to historical average status based on long-term EO-based vegetation products were widely used to delineate abnormal vegetation variation exerted by either climatic or anthropogenic factors (e.g., droughts, wildfires). However, currently available long-term vegetation products may differ from each other in terms of sensors (observational platform or spectral bands), bio-physical definitions (e.g., NDVI, EVI, LAI, and VOD), spatiotemporal resolution, as well as the time-spans, which results in inconsistency across these vegetation products. Taking the VCI as an example, this study evaluated the uncertainty of vegetation anomalies detected based on different vegetation products over the middle reach of the Yangtze River by explicitly considering the effect of sensors, biophysical definitions, and time-spans. The preliminary results showed that VCI derived from NDVI products from different sensors (AVHRR vs. MODIS) induced significant inconsistent anomalies over most landscapes. The differences resulting from products with different biophysical definitions (NDVI vs. EVI, LAI, and VOD) are much lower than those from different sensors but still significant over specific areas. As for the time-spans, the 20-year NDVI based VCI presented a considerable reduction in variance over the study area on average compared to VCI calculated based on 5-year NDVI. In summary, caution should be taken when applying EO-based vegetation products for vegetation anomalies mapping, especially for quantitative assessment.","EO-based vegetation products; uncertainty; vegetation anomalies; Vegetation Condition Index","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","","Optical and Laser Remote Sensing","","",""
"uuid:79c09da5-f071-45cc-87c6-e2bb54854578","http://resolver.tudelft.nl/uuid:79c09da5-f071-45cc-87c6-e2bb54854578","Timetable Scheduling for Passenger-Centric Urban Rail Networks: Model Predictive Control based on a Novel Absorption Model","Liu, X. (TU Delft Team Bart De Schutter); Dabiri, A. (TU Delft Team Azita Dabiri); De Schutter, B.H.K. (TU Delft Delft Center for Systems and Control)","","2022","Timetable scheduling plays a key role in daily operations of urban rail transit systems, as it determines the quality of service provided to passengers. In order to develop efficient timetable scheduling methods, it is necessary to develop a proper model to integrate timetable-related and passenger-related factors in urban rail network efficiently. In this paper, a novel passenger absorption model for passenger- centric urban rail networks is established. The model explicitly integrates time-varying passenger origin-destination demands and the departure frequency of each line for real-time timetable scheduling. Then, a model predictive control (MPC) method for the timetable scheduling problem is proposed based on the developed model. The resulting MPC optimization problem can be formulated as a mixed-integer programming (MILP) problem, which can be solved efficiently by using the existing MILP solvers. The effectiveness of the absorption model and the corresponding MILP-based MPC approach is illustrated through the case study based on two Beijing subway lines.","","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","","Delft Center for Systems and Control","Team Bart De Schutter","","",""
"uuid:687f8ab6-a392-47ba-98bf-df6064b18cfd","http://resolver.tudelft.nl/uuid:687f8ab6-a392-47ba-98bf-df6064b18cfd","Deklagen met epoxymodificatie voor langere levensduur","Naus, Robbert (Dura Vermeer Infra Participaties); Dekkers, Rudi (Dura Vermeer Infra Participaties); Waarts, Paul (Provincie Noord-Holland); Apostolidis, P. (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering)","","2022","In de wegenbouw is duurzaamheid een belangrijk speerpunt. Daarom wordt er gezocht naar nieuwe bindmiddelen en modificaties om duurzame oplossingen te vinden voor de alsmaar groeiende verkeersstromen. Met de introductie van asfalt met epoxygemodificeerde bitumen wordt een grote stap gezet in het realiseren van robuuste wegen met een langere levensduur.
Door de jaren heen is asfalt met epoxybitumen wereldwijd toegepast als een hoogwaardig verhardingsmateriaal met een lange levensduur, vooral als wegdek op stalen brugdekken. In Nieuw-Zeeland wordt sinds 2007 asfalt met epoxybitumen als deklaag gebruikt. Om tot een balans te komen tussen kosten en prestaties wordt daar sinds 2012 gekozen voor een mengvorm van epoxybitumen met gewone bitumen. Inmiddels ligt er al een miljoen vierkante meter ZOAB met epoxygemodificeerde bitumen. In 2017 is door de TU Delft, provincie Noord-Holland en Dura Vermeer het initiatief genomen om epoxygemodificeerde bitumen in Nederland te introduceren.
Aan de TU Delft zijn vanaf 2018 twee PhD’s gestart om epoxygemodificeerde bitumen voor de Nederlandse situatie te onderzoeken. De laboratoriumonderzoeken bij de TU Delft en Dura Vermeer wijzen uit dat de epoxygemodificeerde mengsels in het algemeen betere eigenschappen hebben dan mengsels met standaard bitumen. Asfalt met epoxygemodificeerde bitumen gaat naar verwachting veel langer mee dan de huidige asfaltmengsels. De langere levensduur leidt tot een lagere milieubelasting. De meerkosten ervan zijn aanzienlijk maar vanwege de langere levensduur zijn de life cycle costs lager. Er is minder hinder voor het verkeer omdat de weg minder vaak hoeft te worden voorzien van een nieuwe asfaltlaag. En tenslotte, als het dan uiteindelijk toch versleten is, kan het goed worden hergebruikt.
Het is echter moeilijk om de langere levensduur te kwantificeren, hier is geen algemeen geaccepteerde meetmethode voor. Om de praktijkeigenschappen te monitoren, zijn direct al diverse proefvakken aangelegd. De betere hechting, de betere prestatie na veroudering (zoals vorst-dooi cycli) en de verbeterde weerstand tegen rafeling kunnen duiden op een langere levensduur. Tot nu toe presteren alle proefvakken naar verwachting. De paper beschrijft de proefvakken en enkele proefresultaten.","SMA; ZOAB; epoxygemodificeerde bitumen; langere levensduur; proefvakken","nl","conference paper","","","","","","","","","","","Pavement Engineering","","",""
"uuid:488cad9d-badf-4818-8cb2-1b28d5d44c01","http://resolver.tudelft.nl/uuid:488cad9d-badf-4818-8cb2-1b28d5d44c01","The First Multimodal Information Based Speech Processing (Misp) Challenge: Data, Tasks, Baselines And Results","Chen, Hang (University of Science and Technology of China); Zhou, Hengshun (University of Science and Technology of China); Du, Jun (University of Science and Technology of China); Lee, Chin-Hui (Georgia Institute of Technology); Chen, Jingdong (Northwestern Polytechnical University); Watanabe, Shinji (Carnegie Mellon University); Siniscalchi, Sabato Marco (Georgia Institute of Technology; University of Enna Kore); Scharenborg, O.E. (TU Delft Multimedia Computing); Liu, Di-Yuan (iFlytek)","","2022","In this paper we discuss the rational of the Multi-model Information based Speech Processing (MISP) Challenge, and provide a detailed description of the data recorded, the two evaluation tasks and the corresponding baselines, followed by a summary of submitted systems and evaluation results. The MISP Challenge aims at tack-ling speech processing tasks in different scenarios by introducing information about an additional modality (e.g., video, or text), which will hopefully lead to better environmental and speaker robustness in realistic applications. In the first MISP challenge, two bench-mark datasets recorded in a real-home TV room with two reproducible open-source baseline systems have been released to promote research in audio-visual wake word spotting (AVWWS) and audio-visual speech recognition (AVSR). To our knowledge, MISP is the first open evaluation challenge to tackle real-world issues of AVWWS and AVSR in the home TV scenario.","MISP challenge; microphone array; audio-visual; automatic speech recognition; wake word spotting","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","","","Multimedia Computing","","",""
"uuid:3e0be03a-0c0c-4b0c-9976-b7249e7a3f5f","http://resolver.tudelft.nl/uuid:3e0be03a-0c0c-4b0c-9976-b7249e7a3f5f","Robust Adaptive Back-Stepping Control Approach Using Quadratic Lyapunov Functions for MMC-Based HVDC Digital Twins","Liu, L. (TU Delft Intelligent Electrical Power Grids); Lekić, A. (TU Delft Intelligent Electrical Power Grids); Popov, M. (TU Delft Intelligent Electrical Power Grids)","Margaria, Tiziana (editor); Steffen, Bernhard (editor)","2022","Due to its excellent performance, VSC-based high voltage direct current (HVDC) power systems draw significant attention. They are being heavily used in modern industrial applications, such as onshore and offshore wind farms, and for interconnection between asynchronous networks. However, the traditional proportional-integral (PI) control method is not robust enough to track the reference signal quickly and accurately during significant system disturbances. This paper proposes a robust adaptive back-stepping control (BSC) method that secures vulnerable power-electronic equipment. The adaptive BSC controller regulates the sum of capacitor energy, and the AC grid current through decoupled and closed control-loop design. The major advantage of the proposed control approach is the smooth transient response and accurate tracking ability, which is superior to classical control methods. In addition, the proposed methods have the merits of systematic and recursive design methodology and demand a low processing burden for Lyapunov functions and control laws. Moreover, the implementation particularities of the proposed approach are illustrated and verified for a power system digital twin using real-time digital simulator (RTDS).","Adaptive back-stepping control; Digital twins; Energy controller; HVDC grids; Lyapunov stability; MMC; Nonlinear robust control; RTDS","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.","","2023-04-17","","","Intelligent Electrical Power Grids","","",""
"uuid:01ecc5f8-655b-4224-bada-e05a552efa33","http://resolver.tudelft.nl/uuid:01ecc5f8-655b-4224-bada-e05a552efa33","A Cooperative Protocol for Vehicle Merging Using Bi-dimensional Artificial Potential Fields","Liu, Zhengqiang (Southeast University); Liu, Di (Southeast University; Rijksuniversiteit Groningen); Yu, Wenwu (Southeast University); Baldi, S. (TU Delft Team Bart De Schutter; Southeast University)","Kim, Jinwhan (editor); Englot, Brendan (editor); Park, Hae-Won (editor); Choi, Han-Lim (editor); Myung, Hyun (editor); Kim, Junmo (editor); Kim, Jong-Hwan (editor)","2022","In recent years, platooning solutions like cooperative adaptive cruise control (CACC) have been deeply studied. It is common in such platooning literature to assume that the vehicles drive on the same lane (longitudinal platooning). At the same time, lateral control during merging maneuvers is commonly addressed as a path planning problem, in which the ego vehicle changes the lane during merging without necessarily cooperating with its neighboring vehicles (i.e. without considering gap closing). The primary objective of this article is to develop a control strategy which involves both longitudinal and lateral vehicle dynamics, where the vehicles merge and form a platoon in a cooperative way without a priori path planning. Appropriately designed bi-dimensional artificial potential fields are used to achieve this goal and the proposed protocol is verified through simulations with CarSim.","Artificial potential fields; Lateral control; Longitudinal control; Merging maneuver; Platooning","en","conference paper","Springer","","","","","Accepted Author Manuscript","","2023-04-01","","","Team Bart De Schutter","","",""
"uuid:6292c751-ff40-436e-9ff6-33e60fffc27d","http://resolver.tudelft.nl/uuid:6292c751-ff40-436e-9ff6-33e60fffc27d","Blade Effective Wind Speed Estimation: A Subspace Predictive Repetitive Estimator Approach","Liu, Y. (TU Delft Team Riccardo Ferrari); Pamososuryo, A.K. (TU Delft Team Jan-Willem van Wingerden); Ferrari, Riccardo M.G. (TU Delft Team Riccardo Ferrari); Hovgaard, Tobias Gybel (Vestas Technology R&D); van Wingerden, J.W. (TU Delft Team Jan-Willem van Wingerden)","","2021","Modern wind turbine control algorithms typically utilize rotor effective wind speed measured from an anemometer on the turbine’s nacelle. Unfortunately, the measured wind speed from such a single measurement point does not give a good representation of the effective wind speed over the blades, as it does not take the varying wind condition within the entire rotor area into account. As such, Blade Effective Wind Speed (BEWS) estimation can be seen as a more accurate alternative. This paper introduces a novel Subspace Predictive Repetitive Estimator (SPRE) approach to estimate the BEWS using blade load measurements. In detail, the azimuth-dependent cone coefficient is firstly formulated to describe the mapping between the out-of-plane blade root bending moment and the wind speed over blades. Then, the SPRE scheme, which is inspired by Subspace Predictive Repetitive Control (SPRC), is proposed to estimate the BEWS. Case studies exhibit the proposed method’s effectiveness at predicting BEWS and identifying wind shear in varying wind speed conditions. Moreover, this novel technique enables complicated wind inflow conditions, where a rotor is impinged and overlapped by wake shed from an upstream turbine, to be estimated.","","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","","","Team Riccardo Ferrari","","",""
"uuid:123b5651-3440-41c8-9e3e-b4f5928f19aa","http://resolver.tudelft.nl/uuid:123b5651-3440-41c8-9e3e-b4f5928f19aa","Analysis of Thrust-Scaled Acoustic Emissions of Aircraft Propellers and Their Dependence on Propulsive Efficiency","Geng, Xin (Beihang University); Hu, Tianxiang (Beihang University); Liu, Peiqing (Beihang University); Sinnige, T. (TU Delft Flight Performance and Propulsion); Eitelberg, G. (TU Delft Flight Performance and Propulsion)","","2021","The increasing demand for short-range passenger air transport and the strong push for aircraft with electric propulsion has renewed research interest in propellers. Despite the unmatched aerodynamic efficiency of propellers, their relatively high noise emissions limit widespread application on aircraft. Previous research has not systematically addressed the tradeoff between aerodynamic and aeroacoustic performance. This paper presents the results of an optimization study aimed at minimizing propeller noise without compromising aerodynamic efficiency. In the optimization, a blade-element-momentum-theory (BEMT) model is utilized which accounts for the effects of blade sweep on the blade loading. This BEMT model is coupled to a frequency-domain code for tonal noise prediction. A novel scaling approach is presented to directly relate the propeller noise emissions to the propeller thrust. Dedicated wind-tunnel experiments were performed to validate the analysis models. Good agreement between numerical and experimental results is obtained at low to moderate blade loading conditions. The optimization study shows that the blade sweep is an important design parameter to simultaneously maximize aerodynamic and acoustic performance. Compared to a modern baseline design, a noise reduction of 2.9 dB is achieved without reduction in propeller efficiency.","","en","conference paper","International Council of the Aeronautical Sciences","","","","","","","2021-09-11","","","Flight Performance and Propulsion","","",""
"uuid:d0d41806-94ec-4df7-8c84-902e1908af45","http://resolver.tudelft.nl/uuid:d0d41806-94ec-4df7-8c84-902e1908af45","Effect of bio-oil on low-intermediate temperature properties of organosolv lignin-bitumen","Zhang, Y. (TU Delft Pavement Engineering; Chang'an University); Liu, X. (TU Delft Pavement Engineering); Ren, S. (TU Delft Pavement Engineering); Jing, R. (TU Delft Pavement Engineering); Gard, W.F. (TU Delft Bio-based Structures & Materials); Apostolidis, P. (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Petroleum Institute)","Chen, Xianhua (editor); Yang, Jun (editor); Oeser, Markus (editor); Wang, Haopeng (editor)","2021","Lignin, one of the most abundant natural polymers, has been extensively studied as liquid or solid additive in bituminous binders. Despite the fact the organosolv lignin in bitumen improves the overall resistance against oxidative aging, lignin could lead to binders of high thermal cracking sensitivity. In this study, a bio-based oil is implemented in a lignin modified bitumen to ameliorate characteristics, such as fatigue and thermal cracking resistance. Pressure aging vessel conditioning was applied to new binders formulated by different proportions of bio-oil to simulate the long-term aging. A series of rheological tests were performed. Based on the linear amplitude sweep test results, fatigue damage of lignin-bitumen could be reduced by increasing the oil content. According to relaxation test results, the addition of oil significantly decreased the ratio of residual stress and relaxation time. This study has shown preliminary conclusions on the use of bio-oil to improve the low-intermediate temperature performance of lignin-bitumen binders.","","en","conference paper","CRC Press / Balkema - Taylor & Francis Group","","","","","","","2021-06-29","","","Pavement Engineering","","",""
"uuid:7bd400eb-4858-4dfa-823d-2a8c3301a7f2","http://resolver.tudelft.nl/uuid:7bd400eb-4858-4dfa-823d-2a8c3301a7f2","Use of waste oil/styrene-butadiene-rubber blends as rejuvenators for aged bitumen","Ren, S. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Lin, P. (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering)","Chen, Xianhua (editor); Yang, Jun (editor); Oeser, Markus (editor); Wang, Haopeng (editor)","2021","This study elaborates the influence of blends formulated by waste oil (WO) and styrene-butadiene rubber (SBR) on thermo-mechanical and chemical compositional characteristics of rejuvenated bitumen. The results show that both WEO (waste engine oil) and WCO (waste cooking oil) can compensate viscous component for reclaimed bitumen, and the effect of WCO is more significant. However, WO-rejuvenated bitumen has considerable drawbacks in terms of temperature susceptibility and flow resistance, but dramatic improvement after being added with SBR has been noticed. Furthermore, the rejuvenation mechanism of WO/SBR blends is revealed by using FTIR tests, which shows that the physical blending mainly determines the rejuvenation mechanism when the WO/SBR blends are used in bitumen. The combination of WO and SBR is beneficial for improving the temperature susceptibility and rutting resistance of rejuvenated bitumen.","","en","conference paper","CRC Press / Balkema - Taylor & Francis Group","","","","","Accepted Author Manuscript","","2021-12-29","","","Pavement Engineering","","",""
"uuid:0a2d8fbe-0db3-4f82-a878-a30bbbb66dcc","http://resolver.tudelft.nl/uuid:0a2d8fbe-0db3-4f82-a878-a30bbbb66dcc","Critical Components Identification for Cyber-Physical Power Systems Considering Time-Varying Operational States","Liu, Y. (TU Delft Intelligent Electrical Power Grids; TU Delft Electrical Sustainable Energy); Semertzis, I. (TU Delft Intelligent Electrical Power Grids; TU Delft Electrical Sustainable Energy); Stefanov, Alexandru (TU Delft Intelligent Electrical Power Grids; TU Delft Electrical Sustainable Energy); Palensky, P. (TU Delft Intelligent Electrical Power Grids; TU Delft Electrical Sustainable Energy)","Palensky, Peter (editor); Srivastava, Anurag (editor)","2021","The security issues of Cyber-Physical power Systems (CPS) have attracted widespread attention from scholars. Vulnerability assessment emerges as an effective method to identify the critical components and thus increase the system resilience. While efforts have been made to study the vulnerability features of power systems under the occurrence of a single, discrete disturbance or failure at a specific time instant, this paper focuses on identifying the critical components of the cyber-physical system considering time-varying operational states. To investigate the potentially ever-changing CPS vulnerability features, in this paper we construct a database of cascading failure chains using quasi-dynamic simulations to capture the vulnerability relationships among components under time-varying operational states. Then, by adopting sequential mining algorithms, we mine the most frequent cascading failure patterns and identify the critical components based on the data mining results. Simulation studies are conducted on IEEE 39-bus and IEEE RTS-96 systems to evaluate the effectiveness of the proposed method for the identification of critical components at both cyber and physical layers.","Cyber-Physical Systems; Data Mining Algorithms; Vulnerability Assessment; Power Systems","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","Electrical Sustainable Energy","Intelligent Electrical Power Grids","","",""
"uuid:3b2e81a8-fb83-4275-b438-78c1171fc778","http://resolver.tudelft.nl/uuid:3b2e81a8-fb83-4275-b438-78c1171fc778","Internal and near-wall flow fields around a structured porous coated cylinder and their role in passive flow and noise control","Arcondoulis, Elias J. G. (Southern University of Science and Technology); Liu, Yu (Southern University of Science and Technology); Yang, Yannian (Southern University of Science and Technology); Ragni, D. (TU Delft Wind Energy); Rubio Carpio, A. (TU Delft Wind Energy); Avallone, F. (TU Delft Wind Energy)","","2021","View Video Presentation: https://doi-org.tudelft.idm.oclc.org/10.2514/6.2021-2226.vid
The mechanisms responsible for vortex shedding reduction, due to the application of a porous coating to a smooth cylinder placed in uniform flow, are still uncertain despite several numerical and experimental studies. To help understand these mechanisms, a transparent Structured Porous Coated Cylinder (SPCC) was manufactured to investigate the internal and near-wall flow fields. The SPCC mimics the more commonly used porous materials such as metal foam and polyurethane, that possess randomized structures preventing a clear line-of-sight along the span and circumference of the porous layers. Tomographic Particle Image Velocimetry was used in a water-tunnel facility to investigate three small regions of an SPCC, on the windward, mid-region and leeward sides. In this paper, previously unseen experimentally obtained internal flow fields of a porous coated cylinder are presented. The following summarize the key observations (1) stagnation from freestream flow to the inner cylinder diameter in the windward region, (2) boundary layer profiles within the porous layer in the circumferential mid-region and (3) bleeding from the porous layer into the wake in the leeward region. These results provide key experimental findings for comparison and validation of numerical simulations of bulk porous media, such as the Darcy-Forscheimer method used in conjunction with the Ffowcs Williams-Hawkings acoustic analogy.","","en","conference paper","","","","","","","","","","","Wind Energy","","",""
"uuid:1d347d76-e56f-4106-8fa5-445d43da50db","http://resolver.tudelft.nl/uuid:1d347d76-e56f-4106-8fa5-445d43da50db","Global Optimization of Low-Thrust Interplanetary Trajectories Using a Machine Learning Surrogate","Gómez Pérez, P. (Student TU Delft); Liu, Y. (TU Delft Astrodynamics & Space Missions); Cowan, K.J. (TU Delft Astrodynamics & Space Missions)","Wilson, Roby (editor); Shan, Jinjun (editor); Howell, Kathleen (editor); Hoots, Felix (editor)","2021","In this work, we propose a new method to approximate the cost function of Low-Thrust, Multiple-Gravity-Assist interplanetary trajectories using a Machine Learning surrogate. We identified the computation time required to obtain training data as the main limitation when using Machine Learning methods for this purpose so we present a strategy to build the surrogate with limited training data. We built an Online-Sequential Extreme Learning Machine Multi-Agent System (OS-ELM-MAS) surrogate due to its theoretical good performance when the training data is limited. In addition, we define a method to include the surrogate during the optimization process that can be used with any gradient-free algorithm, and study the effect of several surrogate parameters on the optimization results. Finally, several interplanetary trajectories are optimized with and without the surrogate. Employing the surrogate results in up to 12% lower fuel cost values after a fixed optimization time. The parameters that control the interaction have to be carefully selected to achieve this improvement, and we show that the optimal value of these parameters can be narrowed down based on the characteristics of the transfers.","","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.","","2021-12-20","","","Astrodynamics & Space Missions","","",""
"uuid:b3521dd9-ec1b-41a0-8770-719d7e82373c","http://resolver.tudelft.nl/uuid:b3521dd9-ec1b-41a0-8770-719d7e82373c","Fabrication of Nanoslits with <111> Etching TSWE Method","Hong, H. (TU Delft Electronic Components, Technology and Materials; Tsinghua University); Ye, Li (Tsinghua University); Li, Ke (Beijing Jiaotong University); Sarro, Pasqualina M (TU Delft Electronic Components, Technology and Materials); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials); Liu, Zewen (Tsinghua University)","","2021","In this paper, we report a modified three step anisotropic wet etching (TSWE) method to fabricate solid-state silicon nanoslits. The slit-opening process is performed by <111> crystal plane etching. The etching rate of the <111> crystal plane is reasonably slow as it is only 1/45 of the <100> etching rate, thus allowing and therefore good slits-opening controllability. By slowly etching the <111> crystal plane, the over-etching was effectively reduced. Perfectly rectangular nanoslits with different dimensions were successfully obtained. The smallest achieved feature size of the nanoslit is 8.3 nm.","","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.","","2021-11-07","","","Electronic Components, Technology and Materials","","",""
"uuid:f5ffc3f8-bdc6-4f97-89fc-29298b60dbd7","http://resolver.tudelft.nl/uuid:f5ffc3f8-bdc6-4f97-89fc-29298b60dbd7","An end-to-end geometric deficiencies elimination algorithm for 3D meshes","Ma, Bingtao (University of Chinese Academy of Sciences); Liu, Hongsen (University of Chinese Academy of Sciences); Nan, L. (TU Delft Urban Data Science); Tang, Xu (Chinese Academy of Sciences); Fan, Huijie (Chinese Academy of Sciences); Cong, Yang (Chinese Academy of Sciences)","","2021","The 3D mesh is an important representation of geometric data. It is widely used in computer graphics and has attracted more attention in computer vision community recently. However, in the generation of mesh data, geometric deficiencies (e.g., duplicate elements, degenerate faces, isolated vertices, self-intersection, and inner faces) are unavoidable. Geometric deficiencies may violate the topology structure of an object and affect the use of 3D meshes. In this paper, we propose an end-to-end algorithm to eliminate geometric deficiencies effectively and efficiently for 3D meshes in a specific and reasonable order. Specifically, duplicate elements can be first eliminated by assessing appear times of vertices or faces. Then, degenerate faces can be removed according to the outer product of two edges. Next, since isolated vertices do not appear in any face vertices, they can be deleted directly. Afterward, self-intersecting faces are detected and remeshed by using an AABB tree. Finally, we detect and remove an inner face according to whether multiple random rays shooted from a face can reach infinity. Experiments on ModelNet40 dataset illustrate that our method can eliminate the deficiencies of 3D meshes thoroughly.","3D Mesh; Geometric deficiencies; Mesh repair","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.","","2021-08-05","","","Urban Data Science","","",""
"uuid:426eee20-2d7d-43b2-b405-7623a1c26343","http://resolver.tudelft.nl/uuid:426eee20-2d7d-43b2-b405-7623a1c26343","Helping users discover perspectives: Enhancing opinion mining with joint topic models","Draws, T.A. (TU Delft Web Information Systems); Liu, Jody (Student TU Delft); Tintarev, N. (TU Delft Web Information Systems)","O'Conner, L. (editor)","2021","Support or opposition concerning a debated claim such as abortion should be legal can have different underlying reasons, which we call perspectives. This paper explores how opinion mining can be enhanced with joint topic modeling, to identify distinct perspectives within the topic, providing an informative overview from unstructured text. We evaluate four joint topic models (TAM, JST, VODUM, and LAM) in a user study assessing human understandability of the extracted perspectives. Based on the results, we conclude that joint topic models such as TAM can discover perspectives that align with human judgments. Moreover, our results suggest that users are not influenced by their pre-existing stance on the topic of abortion when interpreting the output of topic models.","debated topics; joint topic models; perspective discovery; sentiment analysis; topic modeling","en","conference paper","IEEE","","","","","Virtual/online event due to COVID-19","","","","","Web Information Systems","","",""
"uuid:0bc0b71f-3b1c-442b-bc35-fc92397c3aee","http://resolver.tudelft.nl/uuid:0bc0b71f-3b1c-442b-bc35-fc92397c3aee","Game Engine-based Point Cloud Visualization and Perception for Situation Awareness of Crisis Indoor Environments","Liu, Zhenyu (Student TU Delft); Fu, Runnan (Student TU Delft); Wang, Linjun (Student TU Delft); Jin, Yuzhen (Student TU Delft); Papakostas, Theodoros (Student TU Delft); Mainelli, Xenia Una (Student TU Delft); Voûte, R.L. (TU Delft GIS Technologie; CGI Nederland B.V); Verbree, E. (TU Delft GIS Technologie)","Basiri, Anahid (editor); Gartner, Georg Gartner (editor); Huang, Haosheng (editor)","2021","Because unknown interior layouts can have serious consequences in time-sensitive situations, crisis response teams request many potential solutions for visualizing indoor environments in crisis scenarios. This research uses a game engine to directly visualize point cloud data input of indoor environments for generating clear interaction between the environment and viewers, to aid decision-making in high-stress moments. The prospective final product is an integration of game-oriented visualization and cartography, hosted within Unreal Engine 4 (UE4), allowing users to navigate throughout an indoor environment, and customizing certain interaction features. The UE4 project consists of 4 modules: data preprocessing, render style, functional module, and user interface. Finally, this research uses a single-floor indoor point cloud dataset collected from a building in Rotterdam, the Netherlands for the implementation.","Game Engine; Unreal Engine 4; 3D Visualization; Situation Awareness; Point Cloud; Indoor Environment; Crisis Scenario","en","conference paper","TU Wien","","","","","","","","","","GIS Technologie","","",""
"uuid:0216efea-5910-417d-834a-fd3d10a2ffe6","http://resolver.tudelft.nl/uuid:0216efea-5910-417d-834a-fd3d10a2ffe6","Periodic Load Rejection for Floating Offshore Wind Turbines via Constrained Subspace Predictive Repetitive Control *","Liu, Y. (TU Delft Team Riccardo Ferrari); Ferrari, Riccardo M.G. (TU Delft Team Riccardo Ferrari); van Wingerden, J.W. (TU Delft Team Jan-Willem van Wingerden)","","2021","Individual Pitch Control (IPC) is an effective control strategy to mitigate the blade loads on large-scale wind turbines. Since IPC usually requires high pitch actuation, the safety constraints of the pitch actuator should be taken into account when designing the controller. This paper introduces a constrained Subspace Predictive Repetitive Control (SPRC) approach, which considers the limitation of blade pitch angle and pitch rate. To fulfill this goal, a model predictive control scheme is implemented in the fully data-driven SPRC approach to incorporate the physical limitations of the pitch actuator in the control problem formulation. An optimal control law subjected to constraints is then formulated so that future constraint violations are anticipated and prevented. Case studies show that the developed constrained SPRC reduces the pitch activities necessary to mitigate the blade loads when experiencing wind turbulence and abrupt wind gusts. More importantly, the approach allows the wind farm operator to design conservative bounds for the pitch actuator constraints that satisfies safety limitations, design specifications and physical restrictions. This will help to alleviate the cyclic fatigue loads on the actuators, increase the structural reliability and extend the lifespan of the pitch control system.","","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.","","2022-01-28","","","Team Riccardo Ferrari","","",""
"uuid:e80e9a22-0008-4684-8676-c67d0518b2d6","http://resolver.tudelft.nl/uuid:e80e9a22-0008-4684-8676-c67d0518b2d6","End-to-end language diarization for bilingual code-switching speech","Liu, Hexin (Nanyang Technological University); Perera, Leibny Paola Garcia (Johns Hopkins University); Zhang, Xinyi (Nanyang Technological University); Dauwels, J.H.G. (TU Delft Signal Processing Systems); Khong, Andy W.H. (Nanyang Technological University); Khudanpur, Sanjeev (Johns Hopkins University); Styles, Suzy J. (Nanyang Technological University)","","2021","We propose two end-to-end neural configurations for language diarization on bilingual code-switching speech. The first, a BLSTM-E2E architecture, includes a set of stacked bidirectional LSTMs to compute embeddings and incorporates the deep clustering loss to enforce grouping of languages belonging to the same class. The second, an XSA-E2E architecture, is based on an x-vector model followed by a self-attention encoder. The former encodes frame-level features into segmentlevel embeddings while the latter considers all those embeddings to generate a sequence of segment-level language labels. We evaluated the proposed methods on the dataset obtained from the shared task B in WSTCSMC 2020 and our handcrafted simulated data from the SEAME dataset. Experimental results show that our proposed XSA-E2E architecture achieved a relative improvement of 12.1% in equal error rate and a 7.4% relative improvement on accuracy compared with the baseline algorithm in the WSTCSMC 2020 dataset. Our proposed XSA-E2E architecture achieved an accuracy of 89.84% with a baseline of 85.60% on the simulated data derived from the SEAME dataset.","Code-switching; End-to-end neural diarization; Language diarization; Language identification; Self-attention","en","conference paper","International Speech Communication Association","","","","","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.","","2022-05-01","","","Signal Processing Systems","","",""
"uuid:7544cd5e-5474-4b64-87ac-c73c504e4d41","http://resolver.tudelft.nl/uuid:7544cd5e-5474-4b64-87ac-c73c504e4d41","Through-Screen Visible Light Sensing Empowered by Embedded Deep Learning","Liu, Hao (Student TU Delft); Ye, Hanting (TU Delft Embedded Systems); Yang, J. (TU Delft Web Information Systems); Wang, Q. (TU Delft Embedded Systems)","","2021","Motivated by the trend of realizing full screens on devices such as smartphones, in this work we propose through-screen sensing with visible light for the application of fingertip air-writing. The system can recognize handwritten digits with under-screen photodiodes as the receiver. The key idea is to recognize the weak light reflected by the finger when the finger writes the digits on top of a screen. The proposed air-writing system has immunity to scene changes because it has a fixed screen light source. However, the screen is a double-edged sword as both a signal source and a noise source. We propose a data preprocessing method to reduce the interference of the screen as a noise source. We design an embedded deep learning model, a customized model ConvRNN, to model the spatial and temporal patterns in the dynamic and weak reflected signal for air-writing digits recognition. The evaluation results show that our through-screen fingertip air-writing system with visible light can achieve accuracy up to 91%. Results further show that the size of the customized ConvRNN model can be reduced by 94% with less than a 10% drop in performance.","embedded AI; embedded deep learning; Through-screen sensing","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Embedded Systems","","",""
"uuid:9ea5db52-f242-4030-8095-e3c28ed8d50d","http://resolver.tudelft.nl/uuid:9ea5db52-f242-4030-8095-e3c28ed8d50d","Assessing the Susceptibility of Existing Pipelines to Hydrogen Embrittlement","Boot, T. (TU Delft Team Vera Popovich); Riemslag, A.C. (TU Delft Team Vera Popovich); Reinton, T.E. (TU Delft Team Vera Popovich); Liu, Ping (IntecSea BV); Walters, C.L. (TU Delft Ship Hydromechanics and Structures); Popovich, V. (TU Delft Team Vera Popovich)","","2021","With fossil fuels being phased out and growing global interest in a hydrogen economy, there is demand for re-purposing existing pipelines for transportation of hydrogen gas. However, hydrogen embrittlement (HE) can limit pipeline steel’s performance. In this study, the effect of hydrogen on the mechanical properties of an X60 base metal (polygonal ferrite/pearlite) and its girth weld (acicular ferrite/pearlite) was measured with a novel slow strain rate tensile (SSRT) test in which hollow pipe-like specimens were internally pressurised with nitrogen and hydrogen gas from 0 to 100 bars. Results showed that exposure to H2 gas at 100 bars reduced the ductility of the base metal by up to 40% and the weld metal by 14%. Reduction in cross-sectional area (%RA) reduced by up to 28% in the base metal and 11% in the weld metal. Fracture surface analysis showed micro-void coalescence as well as quasi-cleavage fracture characteristic of HE. Susceptibility to HE was also observed in the form of secondary longitudinal and internal transverse cracks.","Fractography; Hydrogen embrittlement; In situ testing; Pipeline steel","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.","","2021-08-24","","","Team Vera Popovich","","",""
"uuid:845c4a3a-49de-40b8-a942-a109993d3858","http://resolver.tudelft.nl/uuid:845c4a3a-49de-40b8-a942-a109993d3858","Analysis of Bore Characteristics Using KdV-Based Nonlinear Fourier Transform","Brühl, M. (TU Delft Team Sander Wahls); Wahls, S. (TU Delft Team Sander Wahls); Barranco Granged, Ignacio (National University of Singapore); Liu, Philipp L.-F. (National University of Singapore)","","2020","Bores propagating in shallow water transform into undular bores and, finally, into trains of solitons. The observed number and height of these undulations, and later discrete solitons, is strongly dependent on the propagation length of the bore. Empirical results show that the final height of the leading soliton in the far-field is twice the initial mean bore height. The complete disintegration of the initial bore into a train of solitons requires very long propagation lengths, but unfortunately these required distances are usually not available in experimental tests or nature. Therefore, the analysis of the bore decomposition for experimental data into solitons is difficult and requires further approaches. Previous studies have shown that by application of the nonlinear Fourier transform based on the Korteweg–de Vries equation (KdV-NFT) to bores and long-period waves propagating in constant depth, the number and height of all solitons can be reliably predicted already based on the initial bore-shaped free surface.
Against this background, this study presents the systematic analysis of the leading-soliton amplitudes for non-breaking and breaking bores with different strengths in different water depths in order to validate the KdV-NFT results for non-breaking bores, and to show the limitations of wave breaking on the spectral results. The analytical results are compared with data from experimental tests, numerical simulations and other approaches from literature.","bore; nonlinear Fourier transform; soliton fission","en","conference paper","ASME","","","","","Accepted Author Manuscript","","","","","Team Sander Wahls","","",""
"uuid:3eb663a2-be22-4142-bac8-94aff261c1be","http://resolver.tudelft.nl/uuid:3eb663a2-be22-4142-bac8-94aff261c1be","Microwave heating simulation of asphalt pavements","Wang, H. (TU Delft Pavement Engineering); Apostolidis, P. (TU Delft Pavement Engineering); Zhang, H. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology)","Kumar, A. (editor); Papagiannakis, A.T. (editor); Bhasin, A. (editor); Little, D. (editor)","2020","Microwave heating is a promising heating technology for the maintenance, recycling and deicing of pavement structures. Many experimental studies have been conducted to investigate the microwave heating properties of asphalt mixtures in the laboratory. However, very few studies investigated the application of microwave heating on asphalt pavements. This study aims to simulate microwave heating of paving materials using the finite element method. Results show that the developed three-dimensional model, which couples the physics of electromagnetic waves and heat transfer, shows a great potential for optimizing the design of microwave heating prototypes for pavement applications.","","en","conference paper","Taylor and Francis","","","","","Accepted Author Manuscript","","2021-08-07","","","Pavement Engineering","","",""
"uuid:4866e2e2-5417-4fc4-b63c-ed6c37fcba03","http://resolver.tudelft.nl/uuid:4866e2e2-5417-4fc4-b63c-ed6c37fcba03","Oxidation simulation of thin bitumen film","Apostolidis, P. (TU Delft Pavement Engineering); Wang, H. (TU Delft Pavement Engineering); Zhang, H. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology)","Kumar, A. (editor); Papagiannakis, A.T. (editor); Bhasin, A. (editor); Little, D. (editor)","2020","Oxidative aging is a complex phenomenon in bitumen and its fundamental understanding is needed to optimize paving materials with long-lasting characteristics. This research reports on a diffuse-reaction model for predicting the oxidation of bituminous binders over time and under different conditions. As known, the oxidation of bitumen is affected by the material chemistry, film thickness and temperature. Thus, these factors were considered in this research to simulate the oxidation of a thin bitumen film. Carbon compounds were assumed as the oxidation index of a model bitumen and analyses were performed enabling prediction of chemical compositional changes. In the future, the current model can be used to simulate the actual oxidative aging in (un)modified binders, such as epoxy modified asphalt, presented in a companion paper (Apostolidis et al., Kinetics of Epoxy-Asphalt Oxidation. AM3P).","","en","conference paper","Taylor and Francis","","","","","Accepted Author Manuscript","","2021-08-07","","","Pavement Engineering","","",""
"uuid:ccaca092-bc53-455a-8b89-7b1bf4e0dd41","http://resolver.tudelft.nl/uuid:ccaca092-bc53-455a-8b89-7b1bf4e0dd41","Kinetics of epoxy-asphalt oxidation","Apostolidis, P. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology)","Kumar, A. (editor); Papagiannakis, A.T. (editor); Bhasin, A. (editor); Little, D. (editor)","2020","In-depth understanding of the temperature effect on oxidative aging in epoxy-asphalt blends is needed to enable accurate predictions on material response through their service life. Details of the significance of developing prediction models and tools on oxidative aging of pavement materials are presented in a companion paper (Apostolidis et al., Oxidation Simulation of Thin Bitumen Film. AM3P). In this research, the chemical compositional changes of epoxy modified asphalt binders, with and without filler, were analysed after oven-conditioning by means of Fourier transform infrared (FTIR) spectroscopy. With the carbonyl and sulfoxide compounds as aging indices, the sensitivity of chemical compositional changes of bituminous and epoxy-based systems due to the applied temperatures was observed.","","en","conference paper","Taylor and Francis","","","","","Accepted Author Manuscript","","2021-08-07","","","Pavement Engineering","","",""
"uuid:a6006b83-0cb6-440b-8a38-6c6ff8920ea9","http://resolver.tudelft.nl/uuid:a6006b83-0cb6-440b-8a38-6c6ff8920ea9","Preliminary study on using lignin as aging inhibitor in bitumen","Zhang, Y. (TU Delft Pavement Engineering; Chang'an University); Liu, X. (TU Delft Pavement Engineering); Jing, R. (TU Delft Pavement Engineering); Apostolidis, P. (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology)","Kumar, A. (editor); Papagiannakis, A.T. (editor); Bhasin, A. (editor); Little, D. (editor)","2020","During oxidative aging, oxygen reacts with active molecules present in bitumen producing polar compounds, principally ketones and sulfoxides, and increasing in the portion of asphaltenes. In general, oxidation reactions in bitumen yields to change its generic chemical composition and finally its colloidal structure deteriorating the physico-mechanical properties. Lignin is a natural polymer, which has been used in this study as an aging inhibitor to bitumen. Particularly, the effect of aging on the microstructure morphology, surface properties, chemical composition and rheological changes of lignin and the impact of latter as anti-oxidant in bitumen were evaluated. For the purposes of this study, Environmental Scanning Electron Microscope, Helium Pycnometer, Dynamic Vapor Sorption devices and were used to analyze the microstructure, density and specific surface area, respectively. Moreover, Fourier Transform Infrared spectroscopy was used to track the compositional changes in lignin-modified bitumen after PAV aging. Dynamic Shear Rheometer was used to analyze the rheological properties. Overall, decreasing in the carbonyl and sulfoxide compounds were tracked in lignin-modified binders confirm that lignin act as an aging inhibitor in bitumen.","","en","conference paper","Taylor and Francis","","","","","Accepted Author Manuscript","","2021-08-07","","","Pavement Engineering","","",""
"uuid:e81050bd-7813-4df6-afe2-0a3fe83ef871","http://resolver.tudelft.nl/uuid:e81050bd-7813-4df6-afe2-0a3fe83ef871","Dissolution simulation of polymers in bitumen","Wang, H. (TU Delft Pavement Engineering); Apostolidis, P. (TU Delft Pavement Engineering); Zhang, H. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology)","Kumar, A. (editor); Papagiannakis, A.T. (editor); Bhasin, A. (editor); Little, D. (editor)","2020","Fundamental models should be developed and utilized in order to facilitate the chemo-mechanical design of modified binder systems for paving applications but not only. Especially, the fact that the incorporation of new chemical substances used as bio-based modifiers or alternative binders is attracting great interest to replace traditional technologies, the development of tools able to provide insight into the various physio-chemical phenomena is crucial. Among other polymer-bitumen interaction phenomena, the dissolution mechanism of polymers in bitumen is a significant aspect that should be considering in order to enhance binder properties through polymer modification. The current research gives emphasis on modelling the mechanism of dissolution for rubbery polymers in bitumen.","","en","conference paper","Taylor and Francis","","","","","Accepted Author Manuscript","","2021-08-07","","","Pavement Engineering","","",""
"uuid:650dd53e-764c-41f5-9490-a99381daa012","http://resolver.tudelft.nl/uuid:650dd53e-764c-41f5-9490-a99381daa012","Integrated monitoring of subsidence due to hydrocarbon production: Consolidating the foundation","Ketelaar, Gini (Nederlandse Aardolie Maatschappij B.V.); Bähr, Hermann (Nederlandse Aardolie Maatschappij B.V.); Liu, Shizhuo (Nederlandse Aardolie Maatschappij B.V.); Piening, Harry (Nederlandse Aardolie Maatschappij B.V.); van der Veen, Wim (Nederlandse Aardolie Maatschappij B.V.); Hanssen, R.F. (TU Delft Mathematical Geodesy and Positioning); van Leijen, F.J. (TU Delft Mathematical Geodesy and Positioning); van der Marel, H. (TU Delft Mathematical Geodesy and Positioning); Samiei Esfahany, S. (TU Delft Mathematical Geodesy and Positioning)","Fokker, P.A. (editor); Erkens, G. (editor)","2020","This paper describes several geodetic studies that consolidate the reliability and precision of monitoring subsidence due to hydrocarbon production: the deployment of Integrated Geodetic Reference Stations (IGRS); the application of high resolution InSAR; the comparison of different GNSS processing methodologies; the implementation of an efficient InSAR stochastic model, and the framework of integrated geodetic processing (levelling, GNSS, InSAR). The advances that have been made are applicable for any other subsidence monitoring project.","","en","conference paper","IAHS","","","","","Pre-conference publication of a 2020 congress, postponed due to COVID-19","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:08cc6fa4-0278-49af-9741-ea880ffc801b","http://resolver.tudelft.nl/uuid:08cc6fa4-0278-49af-9741-ea880ffc801b","Gaussian process models for preliminary low-thrust trajectory optimization","Bouwman, Lieve (Student TU Delft); Liu, Y. (TU Delft Astrodynamics & Space Missions); Cowan, K.J. (TU Delft Astrodynamics & Space Missions)","Horneman, Kenneth R. (editor); Scott, Christopher (editor); Hansen, Brian W. (editor); Hussein, Islam I. (editor)","2020","Low-thrust trajectories can benefit the search for propellant-optimal trajectories, but increases in modeling complexity and computational load remain a challenge for efficient mission design and optimization. In this paper, an approach for developing models utilizing Gaussian Process (GP) regression and classification is proposed to perform computationally efficient optimization while obtaining acceptable accuracies for trajectories based on exponential sinusoid shaping. The goal of this work is to predict a combination of values of input variables which corresponds to a shape-based trajectory with the smallest total velocity increment (ΔV) or propellant mass fraction (J m). A GP classification model is constructed to assess whether a given combination of values of input variables corresponds to a feasible trajectory. GP regression models are developed to predict the total ΔV and J m corresponding to a combination of shape parameters, which can replace the required integration along the shape. In addition, advanced regression models are developed to predict the target values while requiring only three input parameters, thereby replacing the entire shape computation. In order to develop a GP model that fits the problem at hand, the underlying functions and parameters should be selected rationally. In this work, a novel model development approach is proposed to ensure that the mean function, covariance function, likelihood function, inference method, and hyperparameters, which dominate the performance of the models, are chosen rationally in terms of mean absolute percentage error (MAPE) and prediction time. Using this approach, GP models are developed and tested on transfer trajectories from Earth to Mars and Ceres, and from Mars to Earth, and their performance, in terms of MAPE and prediction time, is compared to that of more common optimization techniques in combination with the exponential sinusoid and other shape-based methods. The results demonstrate that the computation time can significantly be reduced while achieving promising MAPE’s, especially when the goal is to locate regions of feasible or near-optimal trajectories. The proposed model development procedure is tested for robustness, which provides confidence in the proposed approach. Furthermore, it is found that the models which map three input variables directly to a ΔV or J m value perform better than the ones trained with shape information, which demonstrates the strength of GP models as applied to low-thrust trajectory optimization.","","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.","","","","","Astrodynamics & Space Missions","","",""
"uuid:0afee5a5-cfa8-47bc-88db-180dfdfead1e","http://resolver.tudelft.nl/uuid:0afee5a5-cfa8-47bc-88db-180dfdfead1e","Wafer Scale Flexible Interconnect Transfer for Hetrogeneous Integration","Liu, Pan (Fudan University); Li, J. (TU Delft Electronic Components, Technology and Materials); van Zeijl, H.W. (TU Delft Electronic Components, Technology and Materials); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","O'Conner, L. (editor)","2020","A polymer-based wafer level integration technology suitable for miniaturized and multi-functional systems integration was developed and demonstrated in this work. Wafer scale flexible interconnects were firstly fabricated on one wafer, and then transferred to another wafer. Such transfer process involved wafer bonding and application of sacrificial materials. A sacrificial layer was firstly placed on the surface of the transfer wafer, and the sandwich interconnect structures were then manufactured on top of the sacrificial layer. With the help of the sacrificial layer, the flexible interconnects were transferred to another wafer through wafer bonding process. Contact resistance structures were fabricated with the help of wafer bonding process, connecting and aligning metal contact layer on device wafer and metal layer embedded in transferred flexible interconnects. Such transferred contact resistance was measured through designed testing structures as a demo for wafer level heterogeneous integration.","flexible interconnect; heterogeneous integration; transferred interconnect","en","conference paper","IEEE","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:d40089d8-a1bb-46f4-a704-1c90a96cefff","http://resolver.tudelft.nl/uuid:d40089d8-a1bb-46f4-a704-1c90a96cefff","TypeWriter: Neural Type Prediction with Search-Based Validation","Pradel, Michael; Gousios, G. (TU Delft Software Engineering); Liu, Jason; Chandra, Satish","Devanbu, Prem (editor); Cohen, Myra (editor); Zimmermann, Thomas (editor)","2020","Maintaining large code bases written in dynamically typed languages, such as JavaScript or Python, can be challenging due to the absence of type annotations: simple data compatibility errors proliferate, IDE support is limited, and APIs are hard to comprehend. Recent work attempts to address those issues through either static type inference or probabilistic type prediction. Unfortunately, static type inference for dynamic languages is inherently limited, while probabilistic approaches suffer from imprecision. This paper presents TypeWriter, the first combination of probabilistic type prediction with search-based refinement of predicted types. TypeWriter’s predictor learns to infer the return and argument types for functions from partially annotated code bases by combining the natural language properties of code with programming language-level information. To validate predicted types, TypeWriter invokes a gradual type checker with different combinations of the predicted types, while navigating the space of possible type combinations in a feedback-directed manner. We implement the TypeWriter approach for Python and evaluate it on two code corpora: a multi-million line code base at Facebook and a collection of 1,137 popular open-source projects. We show that TypeWriter’s type predictor achieves an F1 score of 0.64 (0.79) in the top-1 (top-5) predictions for return types, and 0.57 (0.80) for argument types, which clearly outperforms prior type prediction models. By combining predictions with search-based validation, TypeWriter can fully annotate between 14% to 44% of the files in a randomly selected corpus, while ensuring type correctness. A comparison with a static type inference tool shows that TypeWriter adds many more non-trivial types. TypeWriter currently suggests types to developers at Facebook and several thousands of types have already been accepted with minimal changes.","Machine learning models of code; Type annotations","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Software Engineering","","",""
"uuid:c58914b2-04a2-4d63-a846-72f46df95cd7","http://resolver.tudelft.nl/uuid:c58914b2-04a2-4d63-a846-72f46df95cd7","Design Considerations and Short-Circuit Characteristics of Fully Superconducting Wind Turbine Generators","Liu, Dong (Hohai University); Hasanov, Urfan (Hohai University); Ye, Changqing (Hohai University); Gou, Xiaofan (Hohai University); Wang, X. (TU Delft Transport Engineering and Logistics)","","2020","Compared with partially superconducting generators, fully superconducting generators (F-SCGs) can further increase the torque density in large direct-drive wind turbine applications. Design trends of F-SCGs intend to increase the electrical loading by applying superconducting wires and boost the current density in the armature winding to meet the critical current density with a safety margin. High currents may cause a low power factor and require the power electronic converter to have a much larger capacity. In an F-SCG, furthermore, torques could be too high, and field and armature currents may exceed the critical currents during a generator short circuit. This paper studies the design of a 20 MW F-SCG with consideration of the control strategy and the power factor, and then evaluates the short circuit characteristic of the F-SCG. The results analysis shows that a capacitive load control should be adopted to avoid a significant drop in the power factor and to make full use of the current-carrying capability of superconductors. An I_{d} = 0 control can also be used with a medium current level. During the short circuit, the negative side is that the phase currents exceed the critical currents and cause quenches. The positive side is that the field currents stay below the critical currents and the torques do not exceed the mechanical limitation of three times the rated torque.","Fully superconducting generator; power factor; short circuit; superconducting armature; wind turbine","en","conference paper","IEEE","","","","","Accepted Author Manuscript","","","","","Transport Engineering and Logistics","","",""
"uuid:8cbba7af-7c18-4576-a18b-c58dbfebeb61","http://resolver.tudelft.nl/uuid:8cbba7af-7c18-4576-a18b-c58dbfebeb61","Action-driven Reinforcement Learning for Improving Localization of Brace Sleeve in Railway Catenary","Zhong, J. (Southwest Jiaotong University); Liu, Zhigang (Southwest Jiaotong University); Wang, H. (TU Delft Railway Engineering); Liu, W. (Southwest Jiaotong University); Yang, Cheng (Southwest Jiaotong University); Nunez, Alfredo (TU Delft Railway Engineering)","","2020","Brace Sleeve (BS) plays an essential role in connecting and fixing cantilevers of railway catenary systems. It needs to be monitored to ensure the safety of railway operations. In the literature, image processing techniques that can localize BSs from inspection images are proposed. However, the boxes produced by existing methods can contain incomplete and/or irrelevant information of the localized BS. This reduces the accuracy of BS condition diagnosis in further analyses. To address this issue, this paper proposes the use of an action-driven reinforcement learning method that adopts the coarse-localized box provided by existing methods, and finds the movements needed for the box to approach to the true BS position automatically and accurately. In contrast to the existing methods that predict one position of the box containing a BS, the proposed action-driven method sees the localization problem as a dynamic position searching process. The localization of BS is achieved by following a sequence of actions, which in this paper are position-moving (up, down, left or right), scale-changing (scale up or scale down) and shape-changing (fatter or taller). The policy of selecting dynamic actions is obtained by reinforcement learning. In the experiment, the proposed method is tested with real-life images taken from a high-speed line in China. The results show that our method can effectively improve the localization accuracy for 81.8% of the analyzed images. We also analyze cases where the method did not improve the localization and suggest further research lines.","action-driven learning; brace sleeve; localization; railway catenary; reinforcement 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.","","2021-05-24","","","Railway Engineering","","",""
"uuid:50def34b-d3a8-4473-9ec1-454e056aa8eb","http://resolver.tudelft.nl/uuid:50def34b-d3a8-4473-9ec1-454e056aa8eb","Coordinative performance of HVDC circuit breakers in MTDC grids","Liu, S. (TU Delft Intelligent Electrical Power Grids; Xi’an Jiaotong University); Shetgaonkar, Ajay (Student TU Delft); Popov, M. (TU Delft Intelligent Electrical Power Grids)","","2020","The objective of this paper is to investigate the coordinative performance of different types of high voltage DC (HVDC) circuit breakers (CBs) in multi-terminal DC (MTDC) grids. Several different HVDC CB technologies are emerging as a solution for the protection of offshore MTDC grids. There is a need for coordinative operation between different types of DC CBs in the same network. In this paper, two typical types of DC CBs are modelled in detail and implemented in a 4terminal MTDC grid in PSCAD environment, by considering operation time, interruption capability and interruption characteristics. Since the requirement of the DC CBs depends on the magnitude of the interrupted current where they are implemented, the fault scenarios in all terminals are studied and the worst scenarios are selected to demonstrate the coordinative performance of different DC CBs. Four cases are defined and demonstrated by two different types of CBs at each terminal of the cable. DC CBs perform differently with the change of the operating time and the locations where they are implemented. The performances and energy absorption are compared and analyzed. The obtained results can be used as DC CB’s selection optimization methodology for future MTDC grids.","Circuit breaker performance; DC grid protection; HVDC circuit breaker; Offshore windfarm","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.","","2021-08-17","","","Intelligent Electrical Power Grids","","",""
"uuid:555ec010-bd73-4879-b3fd-c81e52a3697a","http://resolver.tudelft.nl/uuid:555ec010-bd73-4879-b3fd-c81e52a3697a","A New 'Unified' CPT-Based Axial Pile Capacity Design Method for Driven Piles in Sand","Lehane, Barry M. (University of Western Australia); Liu, Zhongqiang (Norwegian Geotechnical Institute); Bittar, Eduardo (University of Western Australia); Nadim, Farrokh (Norwegian Geotechnical Institute); Lacasse, Suzanne (Norwegian Geotechnical Institute); Jardine, Richard (Imperial College London); Carotenuto, Pasquale (Norwegian Geotechnical Institute); Rattley, Mike (Fugro N.V.); Gavin, Kenneth (TU Delft Geo-engineering)","Westgate, Zack (editor)","2020","This paper outlines the development of a new ‘Unified’ CPT-based method for estimating the axial capacity of driven piles in sand. The method adapts key features of the four CPT-based methods currently in the API and ISO guidelines. The new method was calibrated with the Unified database of pile load tests developed as part of an earlier joint industry research project (Lehane et al. 2017). Key factors known to influence pile capacity are incorporated in the new Unified method formulation, including (i) the degree of soil displacement (plugging) during installation, (ii) the influence of relative pile tip depth, (iii) sand-pile interface friction angle, (iv) changes in radial stress during loading and (v) the influence of loading direction. It is shown that the new method provides more reliable predictions of the capacities of the pile load tests in the Unified database than any of the existing axial pile capacity design methods in the API and ISO guidelines.","","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.","","2021-02-16","","","Geo-engineering","","",""
"uuid:a09db1a3-eb54-408d-ab31-dc27c7b2af6a","http://resolver.tudelft.nl/uuid:a09db1a3-eb54-408d-ab31-dc27c7b2af6a","Adaptive fault accommodation of pitch actuator stuck type of fault in floating offshore wind turbines: A subspace predictive repetitive control approach","Liu, Y. (TU Delft Team Jan-Willem van Wingerden); Frederik, J.A. (TU Delft Team Jan-Willem van Wingerden); Fontanella, A. (Politecnico di Milano); Ferrari, Riccardo M.G. (TU Delft Team Jan-Willem van Wingerden); van Wingerden, J.W. (TU Delft Team Jan-Willem van Wingerden)","","2020","Individual Pitch Control (IPC) is a well-known and, in normal operating conditions, effective approach to alleviate blade loads in wind turbines. However, in the case of a Pitch Actuator Stuck (PAS) type of fault, conventional IPC is not beneficial since its action is disturbed by the failed pitch actuator. In this paper, a Subspace Predictive Repetitive Control (SPRC)-based IPC is proposed to implement a Fault Tolerant Control (FTC) strategy for Floating Offshore Wind Turbines (FOWTs) affected by PAS faults. In particular, an online subspace identification step is first carried out to obtain a linearized model of the FOWT system in faulty condition. The identified FOWT system is then used to develop a repetitive control law. Consequently, the adaptive repetitive control solution is implemented on the remaining healthy pitch actuators, in order to accommodate the PAS fault. Results show the developed SPRC approach allows to accommodate the PAS faults, achieving a considerable reduction of the blade loads in combination with lower pitch activities for the healthy actuators. This allows to continue power production and postpone maintenance operations, thus reducing the OM costs.","","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.","","2021-01-27","","","Team Jan-Willem van Wingerden","","",""
"uuid:2300cb8a-d86f-4f90-bb1a-7cda5eb225c4","http://resolver.tudelft.nl/uuid:2300cb8a-d86f-4f90-bb1a-7cda5eb225c4","Shape feature aided target detection method for micro-drone surveillance radar","Yang, Fawei (Beijing Institute of Technology); Le Kernec, Julien (University of Glasgow); Fioranelli, F. (TU Delft Microwave Sensing, Signals & Systems); Liu, Quanhua (Beijing Institute of Technology)","","2020","This paper presents a shape feature aided target detection method for micro-drone surveillance radar in order to mitigate the false alarms caused by the ground clutter. The method consists of a segmentation threshold selection method based on target measurements and a shape-feature extraction method based on Hu moments. Then the performance of the proposed method is verified experimentally using a real radar system. Field experiment using DJI phantom 3 is conducted, and the measured data is analysed. The results show that although there exist some limitations, the proposed method has good performance on eliminating the false alarms caused by the strong ground clutter in micro-drone detection and improving the target tracking accuracy.","Feature aided; Micro-drone detection; Shape feature extraction","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.","","2022-02-01","","","Microwave Sensing, Signals & Systems","","",""
"uuid:1c68dd28-63da-4aea-9aca-aeeb6d7ea577","http://resolver.tudelft.nl/uuid:1c68dd28-63da-4aea-9aca-aeeb6d7ea577","Design challenges of direct-drive permanent magnet superconducting wind turbine generators","Liu, Dong (Hohai University); Song, Xiaowei (Vestas Wind System A/S); Wang, X. (TU Delft Transport Engineering and Logistics)","","2020","In recent years, permanent magnet superconducting (PMSC) generators have become a candidate for applying superconducting (SC) generators in large direct-drive wind turbines. This configuration keeps the SC armature winding and its cooling system stationary and eliminates rotational cooling couplings. However, the low excitation by permanent magnets may lead to poor power factors if the armature current is high. Furthermore, the permanent magnets are prone to demagnetization when the armature reaction is strong. This paper investigates the design challenges regarding the power factor, demagnetization and short circuit characteristics by analyzing two PMSC generator designs. The results show that the power factor cannot be as high as 0.9 and a low power factor such as 0.6 can take advantage of the high current carrying capability of the SC armature winding. However, this low power factor will cause demagnetization. The armature current may cause quenching of the SC wires during a three-phase short circuit. Demagnetization of the permanent magnets during the short circuit is strong and could be an intrinsic weakness of a PMSC generator.","Demagnetization; MgB2; Permanent magnet; Short circuit; Superconducting generator; Wind turbine","en","conference paper","IEEE","","","","","Accepted Author Manuscript","","","","","Transport Engineering and Logistics","","",""
"uuid:6dedea20-9c00-4539-b201-78e6d798d3a5","http://resolver.tudelft.nl/uuid:6dedea20-9c00-4539-b201-78e6d798d3a5","Comparison of new memory surface hardening models for prediction of high cyclic loading (Comparaison de nouveaux modèles de surface de mémoire à durcissement pour la prévision de fortes charges cycliques)","Diambra, A. (University of Bristol); Corti, R. (University of Bristol); Liu, H. (TU Delft Geo-engineering); Pisano, F. (TU Delft Geo-engineering); Abell, J. A. (Universidad de los Andes)","Sigursteinsson, Haraldur (editor); Erlingsson, Sigurður (editor); Bessason, Bjarni (editor)","2019","This paper presents an objective comparison between two recent constitutive models employing the concept of the hardening memory surface to predict the high cyclic loading behaviour of granular soils. The hardening memory surface is applied to the well-known Severn-Trent sand and the SANINSAND04 constitutive models. While the addition of the new model surface (the memory surface) leads to enhanced model capabilities, slight differences in the implementation can lead to different model performances and simulations. This paper describes the differences between the two implementations and highlights the most relevant modelling ingredi-ents to predict particular features of the cyclic soil behaviour. This paper will help the reader in selecting the most suitable model and related ingredients for a particular geotechnical application.","Constitutive modelling; Cyclic loading; Ratcheting; Sand; Strain accumulation","en","conference paper","Icelandic Geotechnical Society (IGS)","","","","","Accepted Author Manuscript","","","","","Geo-engineering","","",""
"uuid:875f584d-4963-412d-9430-e004dc86ab85","http://resolver.tudelft.nl/uuid:875f584d-4963-412d-9430-e004dc86ab85","Insights into Polymerization-induced Phase Separation of Epoxy-Bitumen Systems and Strategies to Tailor High-Performance Bituminous Materials","Apostolidis, P. (TU Delft Pavement Engineering); Nahar, Sayeda (Latexfalt B.V.); Liu, X. (TU Delft Pavement Engineering); Lommerts, Bert-Jan (Latexfalt B.V.); Erkens, S. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology)","","2019","The utilization of epoxy-based polymers as bituminous modifiers in developing durable and long-lasting pavement structures have gained increasing interest over the last years showing evidence of high performing materials (1-8). It has been noticed that the addition of epoxy-based modifier into bitumen lead to materials with superior characteristics against oxidative aging (1, 3, 8). Next to aging resistance, the incorporation of epoxy modifiers in bituminous materials has added functional benefits, such as improved resistance to moisture damage and fatigue cracking (5, 6). Despite the evidence of aging resistance in epoxy-asphalt concrete mixes, the influence of the epoxy-based polymers on the bitumen aging and the microstructure morphology of newly formed systems have not been fundamentally evaluated yet. Within the scope of this research, the aging susceptibility of epoxy modified bitumen has been investigated. The extent of aging has been probed by using a Fourier Transform Infrared spectrometer and also rheologically evaluated using a dynamic shear rheometer. Furthermore, an improved compatibility between epoxy and bitumen at the microstructural level defines the long-term chemo-mechanical performance of EB systems in a controlled manner. Thus, another aspect of this study was to investigate the morphological and interfacial characteristics of EB microstructure.","","en","conference paper","","","","","","","","","","","Pavement Engineering","","",""
"uuid:b9bb8bce-eb4a-487c-93da-e2363968a409","http://resolver.tudelft.nl/uuid:b9bb8bce-eb4a-487c-93da-e2363968a409","Exploitation of Power-to-Gas for Ancillary Services Provision in the Netherlands","Tuinema, B.W. (TU Delft Intelligent Electrical Power Grids); Ayivor, P.K.S. (TU Delft Intelligent Electrical Power Grids); Garcia Suarez, V. (TU Delft Intelligent Electrical Power Grids); Ebrahim Adabi, M. (TU Delft Intelligent Electrical Power Grids); Liu, L. (TU Delft Intelligent Electrical Power Grids); Rueda, José L. (TU Delft Intelligent Electrical Power Grids); Palensky, P. (TU Delft Intelligent Electrical Power Grids); van der Meijden, M.A.M.M. (TU Delft Intelligent Electrical Power Grids; TenneT TSO B.V.)","","2019","In the future energy system, hydrogen as an energy carrier will play a role of increasing importance. Electrical energy can be converted into hydrogen locally by electrolysers and stored for a relatively long period. Then, the hydrogen can be used by final consumers like the transportation system or industries, as conceptually illustrated in Fig. 1. The flexibility of electrolysers offers promising possibilities for electrical grid support by the provision of ancillary services. Currently, a pilot power-to-gas facility with a 1-MW electrolyser is installed in the northern part of the Netherlands. A larger electrolysis plant of 300 MW may be installed in this area later. The feasibility of this large-scale plant, its impact on the stability of the electrical transmission network and the possibilities for ancillary services provision are currently being investigated in the project TSO2020 [1].","Ancillary Services; Electrolyser; Power System Stability; Real-Time Simulation","en","conference paper","Cigré","","","","","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.","","2021-12-14","","","Intelligent Electrical Power Grids","","",""
"uuid:bd9afb96-7c16-4be6-a5d0-fe5c022935d2","http://resolver.tudelft.nl/uuid:bd9afb96-7c16-4be6-a5d0-fe5c022935d2","Cross Domain Image Matching in Presence of Outliers","Liu, X. (TU Delft Pattern Recognition and Bioinformatics); Khademi, S. (TU Delft Pattern Recognition and Bioinformatics); van Gemert, J.C. (TU Delft Pattern Recognition and Bioinformatics)","","2019","Cross domain image matching between image collections from different source and target domains is challenging in times of deep learning due to i) limited variation of image conditions in a training set, ii) lack of paired-image labels during training, iii) the existing of outliers that makes image matching domains not fully overlap. To this end, we propose an end-to-end architecture that can match cross domain images without labels in the target domain and handle non-overlapping domains by outlier detection. We leverage domain adaptation and triplet constraints for training a network capable of learning domain invariant and identity distinguishable representations, and iteratively detecting the outliers with an entropy loss and our proposed weighted MK-MMD. Extensive experimental evidence on Office [17] dataset and our proposed datasets Shape, Pitts-CycleGAN shows that the proposed approach yields state-of-the-art cross domain image matching and outlier detection performance on different benchmarks. The code will be made publicly available.","Domain adaptation; Image matching; Outlier detection","en","conference paper","","","","","","","","","","","Pattern Recognition and Bioinformatics","","",""
"uuid:7f07410e-93d2-4cd0-8033-cf0067395bab","http://resolver.tudelft.nl/uuid:7f07410e-93d2-4cd0-8033-cf0067395bab","Digital methods for mapping landscape space","Liu, M. (TU Delft Landscape Architecture); Nijhuis, S. (TU Delft Landscape Architecture)","Gao, Lei (editor); Egoz, Shelley (editor)","2019","","Landscape architecture education; mapping; spatio-visual landscape characteristic","en","conference paper","Norwegian University of Life Sciences","","","","","","","","","","Landscape Architecture","","",""
"uuid:22c32ee9-4edf-4986-b6f5-f0cacf422791","http://resolver.tudelft.nl/uuid:22c32ee9-4edf-4986-b6f5-f0cacf422791","Virtual Reality and Convolutional Neural Networks for Railway Catenary Support Components Monitoring","Liu, Wenqiang (Southwest Jiaotong University); Liu, Zhigang (Southwest Jiaotong University); Nunez, Alfredo (TU Delft Railway Engineering)","","2019","The development of algorithms for detecting failures in railway catenary support components has, among others, one major challenge: data about healthy components are much more abundant than data about defective components. In this paper, virtual reality technology is employed to control the learning environment of convolutional neural networks (CNNs) for the automatic multicamera-based monitoring of catenary support components. First, 3D image data based on drawings and real-life video images are developed. Then, a virtual reality environment for monitoring the catenary support system is created, emulating real-life conditions such as measurement noise and a multicamera train simulation to resemble state-of-the-art monitoring systems. Then, CNNs are used to extract and fuse the features of multicamera images. Experiments are conducted for monitoring the cantilever support connection, both down (CSC-D) and up (CSC-U), and registration arm support connection, both down (RASC-D) and up (RASC-U). Experimental results show that the CNNs trained in the virtual reality environment can capture the most relevant spatial information of the catenary support components. Multicamera image detection based on CNNs detects screw loss for all four components. For CSC-D and RASC-U, normal and pin-loss images are also fully detected. A challenge remains in increasing the pin-loss detection for both CSC-U and RASC-D.","","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.","","2020-04-30","","","Railway Engineering","","",""
"uuid:0293bb02-dc64-4711-8354-dd7f3eca13f4","http://resolver.tudelft.nl/uuid:0293bb02-dc64-4711-8354-dd7f3eca13f4","Field Trials with Epoxy Asphalt for Surfacing Layers: Province of North Holland Case Study","Zegard, A. (Dura Vermeer Infra Participaties); Smal, L. (Dura Vermeer Infra Participaties); Naus, R. (Dura Vermeer Infra Participaties); Apostolidis, P. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); van de Ven, Martin (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology)","","2019","The addition of epoxy modifier in bitumen is a relatively new modification technology (1-4) and the most critical epoxy polymerization-induced changes of the epoxy-bituminous materials are not fully understood. Different phenomena take place when epoxy modifiers are incorporated into bitumen and they are dependent on the material hardening conditions. Temperature is one of the most crucial parameters that influences to the development of physical, chemical and mechanical characteristics at the early life (curing or chemical hardening - CH) (5-7) and long-term service (oxidative hardening - OH) (4) of epoxy-modified binders. For this reason, in-depth exploration of epoxy chemistry in bitumen is needed to understand the evolution of the properties of these binders in time.
Within this framework, the chemical compounds and their reaction products generated under various conditions were studied to reveal the time dependency of molecular microstructures of modified binders. Special attention was given to the evaluation of physiochemical characteristics and the mechanical properties of epoxy-bituminous binders, concluding that the degree of CH and OH was dependent on the level of epoxy modification in bitumen. It was observed that the sulfoxide compounds are the most representative index for assessing the age hardening of epoxy-modified bitumens. Finally, the enhanced resistance against environmental aging in combination with the superior mechanical characteristics (i.e., higher tensile strength, flexibility and enhanced longevity) when the epoxy modification is implemented in bitumen promises a very effective technology for developing long-lasting pavement materials.
Within this framework, the chemical compounds and their reaction products generated under various conditions were studied to reveal the time dependency of molecular microstructures of modified binders. Special attention was given to the evaluation of physiochemical characteristics and the mechanical properties of epoxy-bituminous binders, concluding that the degree of CH and OH was dependent on the level of epoxy modification in bitumen. It was observed that the sulfoxide compounds are the most representative index for assessing the age hardening of epoxy-modified bitumens. Finally, the enhanced resistance against environmental aging in combination with the superior mechanical characteristics (i.e., higher tensile strength, flexibility and enhanced longevity) when the epoxy modification is implemented in bitumen promises a very effective technology for developing long-lasting pavement materials.
reduced soil capacity, while the accumulation of shear strains may lead to a violation of serviceability limits. Predicting accurately the soil cyclic behaviour in relation to seismic numerical simulations is still a challenging topic in many respects. Efforts are required to improve several technical aspects, including the development of a reliable and complete constitutive model. This paper reports recent developments after the work of Liu et al. (2018a), and particularly about the performance of a new SANISAND formulation incorporating the memory surface concept (Corti et al., 2016). The performance of the model in terms of strain accumulation and pore pressure build-up is validated against high-quality laboratory test results. A modified dilatancy relationship is given to reproduce within the proposed framework proper cyclic mobility response. The effects of preliminary drained cyclic preloading on soil liquefaction resistance are also studied.","","en","conference paper","Associazione Geotecnica Italiana","","","","","Accepted Author Manuscript","","","","","Geo-engineering","","",""
"uuid:3a5790db-eac9-4c48-86c6-e15651ddbef9","http://resolver.tudelft.nl/uuid:3a5790db-eac9-4c48-86c6-e15651ddbef9","Knowledge Management and Organizational Capabilities in Project settings: Unpacking Project-based Learning","Liu, Y. (TU Delft Integral Design & Management); Papadonikolaki, E. (University College London (UCL)); Houwing, E.J. (TU Delft Integral Design & Management); Hertogh, M.J.C.M. (TU Delft Integral Design & Management)","","2019","Over the last 20 years, there has been an increase in the study of project-based learning to deploy knowledge management strategies and the concept of organizational capability. We address this topic in the context of infrastructure development projects. Through a review of existing literature complemented by pilot empirical research carried out in MultiWaterWork program, and Gaasperdammer tunnel project in the Netherlands, Hong Kong–Zhuhai–Macau Bridge in China and Crossrail in the UK, research propositions are presented on the relationship among knowledge management, project-based learning, and organizational capabilities. The findings reject the position of knowledge management as a best practice toolkit for immediate use and emphasize that there is no pure copy-paste knowledge learned from one project to another. Learning is proposed as the missing link between project capabilities and knowledge management. The study then focuses on the contribution of sets of project capabilities to achieve project performance. It is suggested that the critical role of learning in the development of project capabilities should be on the future research agenda of infrastructure development projects.","knowledge management; learning; capabilities; case study; infrastructure development","en","conference paper","","","","","","","","","","","Integral Design & Management","","",""
"uuid:a900cc34-dd2e-45c5-9dbe-a757d01748c8","http://resolver.tudelft.nl/uuid:a900cc34-dd2e-45c5-9dbe-a757d01748c8","Exploring demand patterns of a ride-sourcing service using spatial and temporal clustering","Liu, T.L.K. (TU Delft Transport and Planning); Krishnakumari, P.K. (TU Delft Transport and Planning); Cats, O. (TU Delft Transport and Planning)","","2019","On-demand transport has become a common mode of transport with ride-sourcing companies like Uber, Lyft and Didi transforming the mobility market. Recurrent patterns in prevailing demand patterns can be used by service providers to better anticipate future demand distribution and thus support demand-Anticipatory fleet management strategies. To this end, we propose three steps for extracting such demand patterns from travel requests: (1) constructing the origin-destination zones by spatial clustering, (2) composing the hourly and daily origin-destination matrix, and; (3) temporal clustering to extract the dynamic demand patterns. We demonstrate the three step approach on the open-source Didi ride-sourcing data. The data consists of travel requests data for November 2016 from Chengdu, China amounting to approximately 6 million rides. The analysis reveals pronounced and recurrent and thus predictable daily and weekly patterns with distinct spatial properties pertaining to ride-sourcing production and attraction characteristics.","demand patterns; ride-sourcing; spatial clustering; taxi data; temporal clustering","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.","","2020-04-28","","","Transport and Planning","","",""
"uuid:1099a43c-9d55-416e-b231-ef1aa7652d8f","http://resolver.tudelft.nl/uuid:1099a43c-9d55-416e-b231-ef1aa7652d8f","Impact of synthetic fibres on asphalt concrete mix","Daniel, C.G. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Apostolidis, P. (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology)","Nikolaides, A.F. (editor); Manthos, E. (editor)","2019","The use of synthetic fibres has been reported to enhance the performance of asphalt pavement materials in terms of permanent deformation, fatigue and thermal cracking. However, limited results about the benefits of synthetic fibres in the reinforced warm-mix asphaltic materials, and the exact mechanism of reinforcing the binding part in pavement structures is still unclear. In this contribution, a semi-circular bending test was per-formed by using various fibre amounts as well as fibre length inside the bituminous mix. The results indicate that the inclusion of fibre can improves the warm-mix performance. Tensile strength as the first criterion is en-hanced proportionally by increasing fibre dosage. The reinforcing effect brought by 38-mm fibre is higher than the one with 19-mm.","","en","conference paper","","","","","","","","","","","Pavement Engineering","","",""
"uuid:45a37317-20e7-4916-a8c2-cb12b1dc3dce","http://resolver.tudelft.nl/uuid:45a37317-20e7-4916-a8c2-cb12b1dc3dce","CluFlow: Cluster-based Flow Management in Software-Defined Wireless Sensor Networks","Liu, Qingzhi (Eindhoven University of Technology); Ozcelebi, Tanir (Eindhoven University of Technology); Cheng, Long (University College Dublin); Kuipers, F.A. (TU Delft Embedded Systems); Lukkien, Johan (Eindhoven University of Technology)","","2019","Software-defined networking (SDN) is a cornerstone of next-generation networks and has already led to numerous advantages for data-center networks and wide-area networks, for instance in terms of reduced management complexity and more fine-grained traffic engineering. However, the design and implementation of SDN within wireless sensor networks (WSN) have received far less attention. Unfortunately, because of the multi-hop type of communication in WSN, a direct reuse of the wired SDN architecture could lead to excessive commu- nication overhead. In this paper, we propose a cluster-based flow management approach that makes a trade-off between the granularity of monitoring by an SDN controller and the communication overhead of flow management. A network is partitioned into clusters with a minimum number of border nodes. Instead of having to handle the individual flows of all nodes, the SDN controller only manages incoming and outgoing traffic flows of clusters through border nodes. Our proof-of- concept implementations in software and hardware show that, when compared with benchmark solutions, our approach is significantly more efficient with respect to the number of nodes that must be managed and the number of control messages exchanged.","Software-defined networking; Wireless sensor networks","en","conference paper","IEEE","","","","","","","","","","Embedded Systems","","",""
"uuid:d1ef55f7-0190-4082-9603-08bec81d6850","http://resolver.tudelft.nl/uuid:d1ef55f7-0190-4082-9603-08bec81d6850","Relaxing the control-gain assumptions of DSC design for nonlinear MIMO systems","Chen, Yong (Air Force Engineering University); Lv, Maolong (TU Delft Team Bart De Schutter); Baldi, S. (TU Delft Team Bart De Schutter; Southeast University); Liu, Zongcheng (Air Force Engineering University); Zhang, Wenqian (Air Force Engineering University); Zhou, Yang (Air Force Engineering University)","","2019","This work focuses on adaptive neural dynamic surface control (DSC) for an extended class of nonlinear MIMO strict-feedback systems whose control gain functions are continuous and possibly unbounded. The method is based on introducing a compact set which is eventually proved to be an invariant set: thanks to this set, the restrictive assumption that the upper and lower bounds of control gain functions must be bounded is removed. This method substantially enlarges the class of systems for which DSC can be applied. By utilizing Lyapunov theorem and invariant set theory, it is rigorously proved that all signals in the closed-loop systems are semi-globally uniformly ultimately bounded (SGUUB) and the output tracking errors converge to an arbitrarily small residual set. A simulation example is provided to demonstrate the effectiveness of the proposed approach.","Adaptive systems; MIMO communication; Stability analysis; Nonlinear systems; Backstepping; Control design","en","conference paper","IEEE","","","","","Accepted Author Manuscript","","","","","Team Bart De Schutter","","",""
"uuid:cb365e80-edac-4575-b0c6-418ac0145b45","http://resolver.tudelft.nl/uuid:cb365e80-edac-4575-b0c6-418ac0145b45","The internal and external flow fields of a structured porous coated cylinder and implications on flow-induced noise","Arcondoulis, Elias J. G. (Southern University of Science and Technology); Ragni, D. (TU Delft Wind Energy); Rubio Carpio, A. (TU Delft Aircraft Noise and Climate Effects); Avallone, F. (TU Delft Wind Energy); Liu, Yu (Southern University of Science and Technology); Yang, Yannian (Southern University of Science and Technology); Li, Zhiyong (Southern University of Science and Technology)","","2019","Porous coated cylinders have been shown to reduce the vortex shedding tone and broadband noise of a bare cylinder placed in uniform flow within specific Reynolds number regimes. The processes by which the vortex shedding and thus tone suppression take place are still uncertain despite numerous numerical and experimental studies. It is understood that adding a porous medium to a bare cylinder will have an influence on the Reynolds number of cylinder, yet the increase of outer diameter alone and the influences of surface roughness are insufficient to explain the changes in the shedding tone magnitude and frequency that are observed by many. Investigating the internal flow field of a porous coated cylinder could lead to a deeper understanding of the flow processes that result in the tonal noise reduction. This has not been achieved to date, as commonly used materials such as metal foam and polyurethane possess randomized porous structures, which make investigating the internal flow field nearly impossible without affecting the structure itself. This paper presents a preliminary analysis of the internal and external flow fields of two structured porous coated cylinders. The cylinders were manufactured using solid transparent materials that possess direct lines of sight through the pores in the axial and spanwise directions. Such structured porous coated cylinders have been previously successful in reducing the typical vortex shedding tone. Tomographic and 2-D planar Particle Image Velocimetry (PIV) were used in a water-tunnel facility to visualize the internal and external flow fields. To date only the 2-D planar PIV results have been post-processed that reveal differences in the wake for the two different cylinder types such as recirculation of flow around the pores. Vorticity flow structures are observed to vary along the cylinder span in the same pattern as the porous structure and streamlines at the windward cylinder side reveal the entry of flow into the porous medium.","","en","conference paper","American Institute of Aeronautics and Astronautics Inc. (AIAA)","","","","","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.","","","","","Aircraft Noise and Climate Effects","","",""
"uuid:5eba261b-39ef-415d-a799-0a09b04480a5","http://resolver.tudelft.nl/uuid:5eba261b-39ef-415d-a799-0a09b04480a5","Enhanced plasticity modelling of high-cyclic ratcheting and pore pressure accumulation in sands","Liu, H. (TU Delft Geo-engineering); Zygounas, Fotis (Student TU Delft); Diambra, A. (University of Bristol); Pisano, F. (TU Delft Geo-engineering)","","2018","Predicting accurately the response of sands to cyclic loads is as relevant as still challenging when many loading cycles are involved, for instance, in relation to offshore or railway geo-engineering applications. Despite the remarkable achievements in the field of soil constitutive modelling, most existing models do not yet capture satisfactorily strain accumulation under high-cyclic drained loading, nor the the build-up of pore pressures under high-cyclic undrained conditions. Recently, bounding surface plasticity enhanced with the concept of memory surface has proven promising to improve sand ratcheting simulations under drained loading conditions (Corti et al. 2016). This paper presents a new model built by combining the memory surface conceptby Corti et al. (2016) with the well-known SANISAND04 bounding surface formulation proposed by Dafalias and Manzari (2004). The outcome is a new sand model that can reproduce phenomenologically the fabric evolution mechanisms governing strain accumulation under long-lasting loading histories (here up to 104 loading cycles). In undrained test simulations, the model proves capable of correctly capturing the rate of pore pressure accumulation, preventing precocious occurrence of cyclic liquefaction.","","en","conference paper","","","","","","","","","","","Geo-engineering","","",""
"uuid:f4494fb8-8f15-457a-a89c-01bd4a02c988","http://resolver.tudelft.nl/uuid:f4494fb8-8f15-457a-a89c-01bd4a02c988","A 0.6V 3.8μW ECG/bio-impedance monitoring IC for disposable health patch in 40nm CMOS","Xu, Jiawei (IMEC); Lin, Qiuyang (Student TU Delft; IMEC); DIng, Ming (Stichting IMEC Nederland); Liu, Y. (TU Delft Bio-Electronics); Van Hoof, Chris (IMEC); Serdijn, W.A. (TU Delft Bio-Electronics); Van Helleputte, Nick (IMEC)","Piovaccari, Alessandro (editor); Wang, Hua (editor)","2018","Simultaneous measurement of Electrocardiogram (ECG) and bio-impedance (BioZ) via disposable health patches is desired for patients suffering from chronic cardiovascular and respiratory diseases. However, a sensing IC must consume ultra-low power under a sub-volt supply to comply with miniaturized and disposable batteries. This work presents a 0.6 V analog frontend (AFE) IC consisting of an instrumentation amplifier (IA), a current source (CS) and a SAR ADC. The AFE can measure ECG and BioZ simultaneously with a single IA by employing an orthogonal chopping scheme. To ensure the IA can tolerate up to 300mVpp DC electrode offset and 400mV pp common-mode (CM) interference, a DC-servo loop (DSL) combined with a common-mode feedforward (CMFF) loop is employed. A buffer-assisted scheme boosts the IA's input impedance by 7x to 140MΩ at 10Hz. To improve the BioZ sensitivity, the CG utilizes dynamic element matching to reduce the 1/f noise of the output current, leading to 35mΩ/√Hz BioZ sensitivity down to 1Hz. The ADC shows a 9.7b ENOB when sampled at 20ksps. The total power consumption of the AFE is 3.8μW.","bio-impedance; ECG; instrumentation amplifier; low noise current source; low supply","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","","","","","","Bio-Electronics","","",""
"uuid:d6a81a6c-ce0d-4f37-a7d6-c61f9b22a0f4","http://resolver.tudelft.nl/uuid:d6a81a6c-ce0d-4f37-a7d6-c61f9b22a0f4","Multi-Objective Performance Evaluation of the Detection of Catenary Support Components Using DCNNs","Liu, W. (Southwest Jiaotong University); Liu, Zhigang (Southwest Jiaotong University); Nunez, Alfredo (TU Delft Railway Engineering); Wang, Liyou (Southwest Jiaotong University); Liu, Kai (Southwest Jiaotong University); Lyu, Yang (Southwest Jiaotong University); Wang, H. (Southwest Jiaotong University)","De Schutter, Bart (editor); Ferrara, Antonella (editor)","2018","The goal of this paper is to evaluate from a multi-objective perspective the performance on the detection of catenary support components when using state-of-the-art deep convolutional neural networks (DCNNs). The detection of components is the first step towards a complete automatized monitoring system that will provide actual information about defects in the catenary support devices. A series of experiments in an unified test environment for detection of components are performed using Faster-CNN, R-FCN, SSD, and YOLOv2. Through the comparison of different assessment indicators, such as precision, recall, average precision and mean average precision, the detection performance of the different DCNNs methods for the components of the catenary support devices is analyzed, discussed and evaluated. The experiment results show that among all considered methods, R-FCN is the more suitable for the detection of catenary support components.","Catenary; Railway Systems; Multi-Objective Performance Evaluation; Deep convolutional neural networks (DCNNs","en","conference paper","","","","","","","","","","","Railway Engineering","","",""
"uuid:98a60e0a-58de-4af5-b23f-5f603d699839","http://resolver.tudelft.nl/uuid:98a60e0a-58de-4af5-b23f-5f603d699839","Autoregressive moving average graph filter design","Liu, J. (TU Delft Signal Processing Systems); Isufi, E. (TU Delft Signal Processing Systems); Leus, G.J.T. (TU Delft Signal Processing Systems)","","2018","In graph signal processing, signals are processed by explicitly taking into account their underlying structure, which is generally characterized by a graph. In this field, graph filters play a major role to process such signals in the so-called graph frequency domain. In this paper, we focus on the design of autoregressive moving average (ARMA) graph filters and basically present two design approaches. The first approach is inspired by Prony's method, which considers a modified error between the modeled and the desired frequency response. The second approach is based on an iterative method, which finds the filter coefficients by iteratively minimizing the true error (instead of the modified error) between the modeled and the desired frequency response. The performance of the proposed design algorithms is evaluated and compared with finite impulse response (FIR) graph filters. The obtained results show that ARMA filters outperform FIR filters in terms of approximation accuracy even for the same computational cost.","Finite impulse response filters; Frequency response; Frequency-domain analysis; Autoregressive processes; Laplace equations; Matrix decomposition","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.","","2021-11-25","","","Signal Processing Systems","","",""
"uuid:9d484b08-96bc-499f-988e-d41af6273a6f","http://resolver.tudelft.nl/uuid:9d484b08-96bc-499f-988e-d41af6273a6f","Inductive bituminous mortar with steel and aluminum fibers","Pavlatos, N. (TU Delft Pavement Engineering); Apostolidis, P. (TU Delft Pavement Engineering); Scarpas, Athanasios (Khalifa University of Science and Technology); Liu, X. (TU Delft Pavement Engineering); van de Ven, Martin (TU Delft Pavement Engineering)","Masad, Eyad (editor); Bhasin, Amit (editor); Scarpas, Tom (editor); Menapace, Ilaria (editor); Kumar, Anupam (editor)","2018","This research presents the implementation of a finite element model analysis for assessing the potential of utilizing alternative fibers for the development of inductive bituminous mixes with lower total weight, higher resistance against corrosion, and sufficient induction heating efficiency. Aluminum fibers are
selected as the metallic modifier in bituminous mixes against the commonly applied steel fibers in order to develop inductive materials. The main reasons for applying aluminum fibers in bituminous mixes are presented in (Pavlatos et al., Framework for replacing steel with aluminum fibers in bituminous mixes, Advances in Materials and Pavement Performance Prediction, Submitted, 2018). A real fiber modified bituminous specimen is reconstructed by means of CT scans and its effective electrical conductivity is calculated assuming steel and aluminum fibers. Since steel fiber modified bituminous mixes have already been used successfully for induction heating, the aim of this work is to demonstrate that aluminum fiber modified bituminous mixes exhibit equally good properties as the steel fiber modified bituminous mixes for induction heating.","","en","conference paper","CRC Press","","","","","","","","","","Pavement Engineering","","",""
"uuid:51aa7fdc-59c5-4b60-89ed-020486231e81","http://resolver.tudelft.nl/uuid:51aa7fdc-59c5-4b60-89ed-020486231e81","Induction hardening of thermoset modified bituminous materials","Apostolidis, P. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Kasbergen, C. (TU Delft Pavement Engineering); van de Ven, Martin (TU Delft Pavement Engineering); Scarpas, Athanasios (Khalifa University of Science and Technology)","Masad, Eyad (editor); Bhasin, Amit (editor); Scarpas, Tom (editor); Menapace, Ilari (editor); Kumar, Anupam (editor)","2018","Induction assisted chemical hardening (curing) or induction hardening is a novel in situ hardening technique for thermoset modified bituminous materials that maintains most of the advantages of natural chemical hardening while eliminating the possible restrictions of longer curing times at lower temperatures. In particular, induction heating can be utilized to accelerate the polymerization of thermoset modified bituminous paving mixes in which inductive particles are added. In this study, steel fibres are dispersed in a thermoset bituminous system and during exposure to an alternating magnetic field, they are induction heated leading to a more rapid initiation of the polymerization. The non-isothermal hardening performance of fast reacting thermoset-bitumen is modelled during the thermoset crosslinking. The model can also be utilized to predict reaction kinetics and viscosity evolution in this material, thereby indicating that induction hardening represents a reliable polymerization method and can be utilized to cure thermoset bituminous materials.","","en","conference paper","CRC Press","","","","","","","","","","Pavement Engineering","","",""
"uuid:aea9802c-2d47-43e1-916a-9be0364e2af4","http://resolver.tudelft.nl/uuid:aea9802c-2d47-43e1-916a-9be0364e2af4","Epoxy modified bitumen: Chemical hardening and its interpretation","Apostolidis, P. (TU Delft Pavement Engineering); Pipintakos, G. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); van de Ven, Martin (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology)","Masad, Eyad (editor); Bhasin, Amit (editor); Scarpas, Tom (editor); Menapace, Ilaria (editor); Kumar, Anupam (editor)","2018","Epoxy modified bitumen (EMB) is a promising technology for long lasting paving materials ensuring higher resistance to rutting, oxygen- and moisture-induced damage. In this paper, an analysis of the chemical reactions that take place during the chemical hardening process (curing) of epoxy modified bitumen
was conducted by means of Fourier Transform Infrared (FT-IR) spectrometer. For various amount of epoxy resin modification in bitumen, the hardening process was evaluated under various conditions. The fluctuation of the most crucial chemical groups occurring during the hardening process was identified and discussed. After the interpretation of chemical hardening, the critical hardening conditions were determined and fatigue tests were performed by Dynamic Shear Rheometer (DSR). Comparison with the unmodified bitumen shows that the fatigue resistance of epoxy modified binders improved significantly with increasing the amount of the epoxy resin in bitumen.","","en","conference paper","CRC Press","","","","","","","","","","Pavement Engineering","","",""
"uuid:12c289e3-060c-4d6e-ae65-e868783389fb","http://resolver.tudelft.nl/uuid:12c289e3-060c-4d6e-ae65-e868783389fb","Induction healing of asphalt mixes with steel slag","Apostolidis, P. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Wang, H. (TU Delft Pavement Engineering); van de Ven, Martin (TU Delft Pavement Engineering); Scarpas, Athanasios (Khalifa University of Science and Technology)","Masad, Eyad (editor); Bhasin, Amit (editor); Scarpas, Tom (editor); Menapace, Ilaria (editor); Kumar, Anupam (editor)","2018","Asphaltic mixes are self-healing materials since they have the capacity to close internal microcracks at higher temperatures or under external force. To trigger their self-healing, asphalt mixes modified with inductive agents can be heated and in that way healed through applying alternating magnetic fields with the aid of an induction coil and this technique is named induction healing. This paper assesses the potential of implementing induction healing in an existing asphalt pavement with steel slag. Cores have been drilled from a field section of a mix with steel slag and were fatigue damaged in an indirect tensile test and healed via induction. The material induction healing potential has been visualized through different X-ray CT scans over the thickness of samples. The induction heating speed of asphalt mixes with steel slag was evaluated as well. The main conclusion in this study was that the total fatigue life of asphalt with steel slag can be enhanced with induction heating. The efficiency of micro-cracks closure was the same over the thickness of asphalt mixes and in combination with the high heating speed (~1.8 °C /sec), induction becomes a very promising alternative for various pavement operations.","","en","conference paper","CRC Press","","","","","","","","","","Pavement Engineering","","",""
"uuid:a10f8dbd-2cb4-4d16-8fac-f9a95a8b3be3","http://resolver.tudelft.nl/uuid:a10f8dbd-2cb4-4d16-8fac-f9a95a8b3be3","Chemo-rheological Study of Hardening of Epoxy Modified Bituminous Binders with the Finite Element Method","Apostolidis, P. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Kasbergen, C. (TU Delft Pavement Engineering); van de Ven, Martin (TU Delft Pavement Engineering); Pipintakos, G. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering; Khalifa University of Science and Technology)","","2018","","","en","conference paper","","","","","","","","2019-09-01","","","Pavement Engineering","","",""
"uuid:c556d207-96cb-4190-a516-aae0c9f34b46","http://resolver.tudelft.nl/uuid:c556d207-96cb-4190-a516-aae0c9f34b46","Numerical investigation of configuration with optimum swirl recovery for propeller propulsion systems","Li, Q. (TU Delft Flight Performance and Propulsion); Liu, Xinyuan (Student TU Delft); Eitelberg, G. (TU Delft Flight Performance and Propulsion); Veldhuis, L.L.M. (TU Delft Flight Performance and Propulsion)","","2018","This paper addresses the design of swirl recovery vanes for propeller propulsion in tractor configuration at cruise conditions using numerical tools. A multi-fidelity optimization framework is formulated for the design purpose, which exploits low-fidelity potential flow-based analysis results as input for high-fidelity Euler equation-based simulations. Furthermore, a model alignment procedure between low-and high-fidelity models is established based on the shape-preserving response prediction algorithm. Two cases of swirl recovery are examined, i.e. swirl recovery by the trailing wing which leads to a reduction of the lift-induced drag, and swirl recovery by a set of stationary vanes (SRVs) located inside the propeller slipstream which leads to production of additional thrust. In the first case, the optimization of the wing circulation distribution is achieved by twist optimization. The resulting reduction in induced drag is 5.9% out of 66.1 counts at the design cruise condition of CL= 0.5. In the case of the SRV design, four configurations are evaluated by locating the vanes at different azimuthal and axial positions relative to the wing. The interactions between SRVs and wing are discussed and an optimum configuration is identified, where the vanes are positioned on the blade-downgoing side downstream of the wing. In this configuration, the wake and tip vortices of the vanes have negligible effect on the wing circulation distribution and consequently introduce no extra drag. With a blade count of 4, the total system drag has decreased by 6.1 counts, which is equivalent to 2.4% of propeller thrust.","","en","conference paper","American Institute of Aeronautics and Astronautics Inc. (AIAA)","","","","","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.","","2022-08-11","","","Flight Performance and Propulsion","","",""
"uuid:f29a6244-510f-446c-9b55-07143f45158b","http://resolver.tudelft.nl/uuid:f29a6244-510f-446c-9b55-07143f45158b","Chemo-mechanics of ageing on bituminous materials","Jing, R. (TU Delft Pavement Engineering); Varveri, Aikaterini (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering)","","2018","Ageing of bitumen is a complex process. It is accompanied by major chemical and mechanical changes. In this study, Fourier Transform Infrared (FTIR) spectrometer and Dynamic Shear Rheometer (DSR) tests were utilized to investigate the effect of ageing on the chemical and mechanical properties of bituminous materials. Bitumen films with thickness of 2 mm were exposed to laboratory ageing at various conditions. Specifically, different combinations of ageing time, temperature and pressure were applied on the materials. The FTIR tests results were used to quantify the changes in the chemical functional groups and to calculate ageing indices (carbonyl index and sulfoxide index) of bitumen. In addition, the DSR tests results were analysed to determine the evolution of the rheological properties of bitumen. A linear relationship was made between the ageing indices and complex shear modulus, providing thus a chemo-mechanics framework to describe bitumen ageing. The results were validated by using data of field aged samples. Finally, the influence of ageing on the parameters of two viscoelastic models was determined.","bitumen; chemomechanics; ageing; viscoelastic model","en","conference paper","","","","","","","","2019-02-01","","","Pavement Engineering","","",""
"uuid:6ece7008-d513-48e0-9145-869754b81fe7","http://resolver.tudelft.nl/uuid:6ece7008-d513-48e0-9145-869754b81fe7","Investigation of the potential use of calcium alginate capsules for self-healing in porous asphalt","Xu, S. (TU Delft Materials and Environment); Liu, X. (TU Delft Pavement Engineering); Tabakovic, A. (TU Delft Materials and Environment; Dublin Institute of Technology; University College Dublin); Schlangen, E. (TU Delft Materials and Environment)","Ye, Guang (editor); Yuan, Yong (editor); Rodriguez, Claudia Romero (editor); Zhang, Hongzhi (editor); Šavija, Branko (editor)","2018","Incorporating self-healing technology in asphalt pavement has been demonstrated to have great potential to prolong its service life. To this aim, the calcium alginate capsules encapsulating rejuvenator were manufactured and proved to have sufficient thermal stability and mechanical resistance to survive the asphalt production and compaction process. In this research, the healing effect of calcium alginate capsules were investigated in porous asphalt concrete. X-ray computed tomography (XCT) was used to visualize the distribution of capsules in porous asphalt concrete. A damaging and healing programme was carried out to evaluate the healing efficiency of these capsules. Semi-circular bending (SCB) tests was employed as a damaging process to investigate the fracture resistance of the porous asphalt concrete samples. The results showed that calcium alginate capsules were able to improve the healing capacity of porous asphalt concrete.","Efflorescence; cement-based exterior wall; mitigation; metakaolin","en","conference paper","Rilem","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-03-01","","","Materials and Environment","","",""
"uuid:53dd8191-e51c-46d0-92bc-0f1ff6caa6e8","http://resolver.tudelft.nl/uuid:53dd8191-e51c-46d0-92bc-0f1ff6caa6e8","Ageing effect on the relaxation properties of bitumen","Jing, R. (TU Delft Pavement Engineering); Varveri, Aikaterini (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering)","Masad, Eyad (editor); Bhasin, Amit (editor); Scarpas, Tom (editor); Menapace, Ilaria (editor); Kumar, Anupam (editor)","2018","The ageing of bitumen has a significant impact on the mechanical behavior of asphalt concrete. In this study, Dynamic Shear Rheometer (DSR) tests were utilized to investigate the effect of ageing on the relaxation properties of bituminous materials. PEN 70/100 bitumen films with thickness of 2 mm were exposed to laboratory ageing at various conditions. Specifically, different combinations of ageing time, temperature and pressure were applied on the bitumen films. Three evaluation indices, explicitly the shear stress at 0 s and 100 s, the ratio of shear stress at 0 s and 100 s and the time that shear stress reduces to 50% and 25% of the initial value, were used to determine the evolution of the relaxation properties of bitumen. The results show that, in comparison to fresh bitumen, aged samples show higher residual shear stresses after relaxation and are more susceptible to stress accumulation thus cracking. In addition, temperature, followed by pressure and ageing time, was found to have the stronger impact on bitumen ageing.","","en","conference paper","CRC Press","","","","","","","","","","Pavement Engineering","","",""
"uuid:62c775d8-f211-4faa-810b-9a397bf21e0d","http://resolver.tudelft.nl/uuid:62c775d8-f211-4faa-810b-9a397bf21e0d","On-site wind powered hydrogen refuelling stations: From national level to a case study in Germany","Chrysochoidis-Antsos, N. (TU Delft Energy Technology); Liu, Changzhi (Student TU Delft); van Wijk, A.J.M. (TU Delft Energy Technology)","Rosa, Felipe (editor); Gabbar, Hossam A. (editor); Lotfi, Mohamed (editor)","2018","Hydrogen refueling stations are an important part of the infrastructural development that should be developed in order to realize a 100% sustainable economy for the future. Most of the refueling stations are located within urban areas but there are many located outside urban areas or in remote areas. Hydrogen could either be transported to these sites or being locally produced with integrated sustainable energy systems. In this study the potential number for wind powered hydrogen refueling stations using GIS is determined. Furthermore the amount of hydrogen that could be produced and used is determined via energy system simulation. Finally the hydrogen production and dispensing costs are calculated.","Case study; GIS data; Hydrogen refueling stations; On-site hydrogen production; System Integration; Wind Turbines","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.","","2019-03-18","","","Energy Technology","","",""
"uuid:f6e444ab-fccd-4a13-8e96-109d4027497f","http://resolver.tudelft.nl/uuid:f6e444ab-fccd-4a13-8e96-109d4027497f","Recurrent Knowledge Distillation","Pintea, S. (TU Delft Pattern Recognition and Bioinformatics); Liu, Yue (KTH Royal Institute of Technology); van Gemert, J.C. (TU Delft Pattern Recognition and Bioinformatics)","","2018","Knowledge distillation compacts deep networks by letting a small student network learn from a large teacher network. The accuracy of knowledge distillation recently benefited from adding residual layers. We propose to reduce the size of the student network even further by recasting multiple residual layers in the teacher network into a single recurrent student layer. We propose three variants of adding recurrent connections into the student network, and show experimentally on CIFAR-10, Scenes and MiniPlaces, that we can reduce the number of parameters at little loss in accuracy.","Knowledge distillation; compacting deep representations for image classification; recurrent layers","en","conference paper","IEEE","","","","","","","","","","Pattern Recognition and Bioinformatics","","",""
"uuid:f0752519-4df4-455a-a9c2-e37ea3249e4e","http://resolver.tudelft.nl/uuid:f0752519-4df4-455a-a9c2-e37ea3249e4e","Towards 10^15-level point clouds management - a nD PointCloud structure","Liu, H. (TU Delft OLD Department of GIS Technology); van Oosterom, P.J.M. (TU Delft OLD Department of GIS Technology); Meijers, B.M. (TU Delft OLD Department of GIS Technology); Verbree, E. (TU Delft OLD Department of GIS Technology)","Mansourian, A. (editor); Pilesjö, P. (editor); Harrie, L. (editor); van Lammeren, R. (editor)","2018","Drastically increasing production of point clouds as well as modern application fields like robotics and virtual reality raises essential demand for smart and highly efficient data management. Effective tools for the managing and direct use of large point clouds are missing. Current state-of-the-art database management systems (DBMS) present critical problems such as inefficient loading/indexing, lack of support of continuous Level of Detail (cLoD) and limited functionalities. Previous research has suggested and demonstrated the importance of converting property dimensions such as time and classification to organizing dimensions for efficient data management at the storage level. However, a thorough validation and theory are still missing. Besides, how new computational platforms such as the cloud technology may support data management also needs further exploration. These problems motivate the PhD research with the focus on a new data structure (nD PointCloud) which is dedicated for smartly and flexibly organizing information of large point clouds for different use cases.","point cloud; data management; data structure; database; dimension","en","conference paper","Association of Geographic Information Laboratories for Europe (AGILE)","","","","","","","","","","OLD Department of GIS Technology","","",""
"uuid:28c63d14-06fa-431c-9d91-b43fd435831d","http://resolver.tudelft.nl/uuid:28c63d14-06fa-431c-9d91-b43fd435831d","Tabu-Based Large Neighbourhood Search for Time-Dependent Multi-Orbit Agile Satellite Scheduling","He, L. (TU Delft Algorithmics; National University of Defense Technology); de Weerdt, M.M. (TU Delft Algorithmics); Yorke-Smith, N. (TU Delft Algorithmics); Liu, Xiaolu (National University of Defense Technology); Chen, Yingwu (National University of Defense Technology)","Bernardini, S. (editor); Parkinson, S, (editor); Talamadupula, K. (editor)","2018","Agile Earth observation satellite (AEOS) scheduling is complex, due to long visible time windows and time-dependent transitions between observations. We introduce a generic approach suited for scheduling problems characterised by time-dependency and/or sequence-dependency. Our approach is a novel hybridization of adaptive large neighbourhood search (ALNS) and tabu search. We further introduce partial sequence dominance and insertion position ordering operators to the ALNS. Extensive computational results on a real-world multi-orbit AEOS observation scheduling benchmark show that the hybrid ALNS robustly outperforms an improved mixed integer programming model and two recent state-of-the-art metaheuristic methods. The proposed method increases solution quality by more than 10% and reduces calculation time by more than 70% on average","","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","","","Algorithmics","","",""
"uuid:f54e922a-bc7e-4af0-8ccd-ad985b5595c7","http://resolver.tudelft.nl/uuid:f54e922a-bc7e-4af0-8ccd-ad985b5595c7","Controlling P and B diffusion during polysilicon formation","Lamers, M.W.P.E. (ECN Solar Energy); Bronsveld, Paula (ECN Solar Energy); Liu, Ji (ECN Solar Energy); Weeber, A.W. (TU Delft Photovoltaic Materials and Devices; ECN Solar Energy)","Brendel, Rolf (editor); Poortmans, Jef (editor); Weeber, Arthur (editor); Hahn, Giso (editor); Ballif, Christophe (editor); Glunz, Stefan (editor); Ribeyron, Pierre-Jean (editor)","2018","High quality passivating contacts can be realized by using the combination of a thin interfacial oxide (SiOx) and doped polysilicon (polySi). Recombination losses are minimized by providing very good passivation between the thin hydrogenated oxide and the cSi, a high field effect by the highly doped polySi [1-2], combined with the low level penetration of dopants in the wafer [2-3]. To realize this low level in-diffusion of dopants, several interacting options are evaluated in this work: the quality of the thin oxide layer (growth method), combined with a diffusion blocking method (nitridation), doping concentration levels in the polySi and temperature of diffusion. It is shown that for Phosphorus (P)-doped polySi, in-diffusion can be reduced by adding an i-layer in between the oxide and the highly doped polySi, lowering the overall doping level in the system slightly. For Boron (B)-doped polySi, in-diffusion can be blocked by nitridation of the SiO2 layer.","","en","conference paper","American Institute of Physics","","","","","","","","","","Photovoltaic Materials and Devices","","",""
"uuid:500f9f3f-310d-4a7b-b236-5e1d935204de","http://resolver.tudelft.nl/uuid:500f9f3f-310d-4a7b-b236-5e1d935204de","Investigation on the DC CB Performance during a Current Interruption Failure at First Current Zero","Liu, S. (Xi’an Jiaotong University); Geng, Yingsan (Xi’an Jiaotong University); Popov, M. (TU Delft Intelligent Electrical Power Grids); Wang, Jianhua (Xi’an Jiaotong University); Liu, Zhiyuan (Xi’an Jiaotong University); Zhang, Bojian (Xi’an Jiaotong University)","Falkingham, Lesli T. (editor); Kaneko, Eiji (editor)","2018","The vacuum interrupter is used as the key component of an active DCCB due to its excellent interruption and dielectric recovery characteristics after current zero. The vacuum interrupter can only interrupt the fault currents below the limitation of a critical di/dt and TIV, otherwise it causes a reignition and the interruption failure. In this paper, a detailed active injection DC CB model is developed, considering operation delay of switches, parasitic parameters of switches and thorough control logic. The limitation dielectric strength between the vacuum gap is defined by the cold break down voltage. Based on the numerical modelling, investigation will be performed to see the performance of DC CB with a failure interruption on the first current zero. The simulation results can help to optimize the injection circuit parameters when DC CB has a failure on the first current zero and has to interrupt in the next current zeros. This algorithm will consider predefined threshold of di/dt, chopping current and variable operation time in different scenarios.","active injection; di/dt; fault interruption; HVDC circuit breaker; PSCAD simulation","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.","","2021-05-03","","","Intelligent Electrical Power Grids","","",""
"uuid:dce70188-46ab-44af-bb79-f755a41167c7","http://resolver.tudelft.nl/uuid:dce70188-46ab-44af-bb79-f755a41167c7","Reliability Modeling Considerations for Emerging Cyber–Physical Power Systems: Prepared by Task Force on Reliability Consideration for Emerging Cyber-Physical Energy Systems under IEEE PES Reliability, Risk and Probability Applications Subcommittee","Aravinthan, Visvakumar (Wichita State University); Balachandran, Thanatheepan (Wichita State University); Ben-Idris, Mohammed (University of Nevada); Fei, Wanghao (University of Oklahoma); Heidari-Kapourchali, Mohammad (Wichita State University); Hettiarachchige-Don, Anton (Wichita State University); Liu, Chen-Ching (Virginia Polytechnic Institute and State University); Stefanov, Alexandru (ESB Networks); Tindemans, Simon H. (TU Delft Intelligent Electrical Power Grids)","","2018","Power system operation considering an increasingly complex cyber infrastructure may be one of the key factors of the next generation power systems. The effective operation of a power system in a massively deployed cyber network environment will be affected by cyber network reliability. Therefore, it is vital not only to understand the operation of a cyber network and its reliability, but also it is critical to integrate the interdependency of cyber and power systems into power system planning and operations. This requires a three-layer approach to reliability modeling and evaluation. The cyber and power layers are interconnected by the information layer. The objective of this paper is to define the three-layer model and report a generalized framework for combined reliability modeling.","cyber-physical power system; dependent system reliability modeling; cyber reliability; cyber-intrusion","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.","","2019-02-20","","","Intelligent Electrical Power Grids","","",""
"uuid:3a8595f0-66b1-45a7-92a4-72da989baf69","http://resolver.tudelft.nl/uuid:3a8595f0-66b1-45a7-92a4-72da989baf69","An Artificial Stream Network and Its Application on Exploring the Effect of DEM Resolution on Hydrological Parameters","Liu, H. (TU Delft OLD Department of GIS Technology)","Mansourian, Ali (editor); Pilesjö, Petter (editor); Harrie, Lars (editor); van Lammeren, Ron (editor)","2018","Digital elevation models (DEM) are widely used in various distributed hydrological models. The stream network can be extracted from it so that runoff routing can be calculated. With the advent of remote sensing and computing technologies, the computation based on DEM with high resolution becomes possible. However, there still exist regions with poor resolution, particularly in developing countries. Previous work only conducted comparisons between results by implementing hydrological models for specific basins in the real world and resolutions were only assigned to several fixed values, such as 30 and 90 m. So, the results derived were thus not in a general sense. To roughly understand how DEM resolution influences the hydrologic response, in this paper, first an artificial stream network of which the principle is originated from fractal theory is constructed. Then by implementing calculation on such artificial networks in an iterative way and performing aggregation, the influence of DEM resolution on several hydrological parameters, namely, the number of basins, drainage density of all basins, total stream length, average stream slope and average topographic index used to assess the spatial distribution of soil saturation of the largest basin can thus be acquired. It is found that DEMs of low resolution would reduce drainage density, total stream length and average stream slope, but would increase topographic index. But the effect is insignificant regarding the number of basins. In the end, the results of the simulation as well as the quality of the fractal terrain are validated by referencing field data.","Fractal terrain; DEM; Stream network; Hydrological parameter","en","conference paper","Springer","","","","","Accepted Author Manuscript","","","","","OLD Department of GIS Technology","","",""
"uuid:8aa9e8b8-6039-4f4c-87df-05609f0c8f3a","http://resolver.tudelft.nl/uuid:8aa9e8b8-6039-4f4c-87df-05609f0c8f3a","Analysis and improvement of railway crossing performance using numerical and experimental approach: application to 1:9 double crossovers","Markine, V.L. (TU Delft Railway Engineering); Liu, X. (TU Delft Railway Engineering); Mashal, Abdul Ahad; Ma, Y. (TU Delft Railway Engineering)","","2017","The paper presents an integrated approach for analysis and improvement of performance of railway crossings. The approach consists of a detailed finite element (FE) model of a wheel rolling over a crossing (validated against the measured crossing accelerations) and experimental tools installed on the crossings in situ. The studied crossings are the cast manganese steel 1:9 crossings. This type of crossings suffers from severe plastic deformations and cracks. The presented approach has been applied to improve the performance of these crossings and to assess the effectiveness of the maintenance actions.
The obtained numerical and experimental results have helped to explain the poor performance of the crossings. Moreover, a number of the design improvements have not only been proposed, but also effectiveness of these improvements have been confirmed by the numerical simulations and/or measurement results.
The results are presented and discussed. More details are in the extended version of this paper.","","en","conference paper","","","","","","","Campus only","","","","Railway Engineering","","",""
"uuid:3420c6e4-5e1a-4ae8-b1a1-54481cffee6e","http://resolver.tudelft.nl/uuid:3420c6e4-5e1a-4ae8-b1a1-54481cffee6e","Form-finding and construction of ice composite shell structures","Wu, Yue (Harbin Institute of Technology); Liu, Xiuming (Harbin Institute of Technology); Li, Q. (TU Delft Structural Design & Mechanics); Chen, Boxuan (Harbin Institute of Technology); Luo, Peng (Harbin Institute of Technology); Pronk, Arno (Eindhoven University of Technology); Mergny, Elke (Université de Liège)","Bögle, Annette (editor); Grohmann, Manfred (editor)","2017","By using inflatable moulds and then spraying cellulose-water mixture, one ice dome and two ice towers were built in Harbin in December 2016. During the whole process, form-finding of the inflatable moulds as well as the construction of these ice composite shell structures are very important for the final results.
The mould for the ice dome structure was a result of the manipulation of a synclastic membrane with a rope net. The mould for the ice tower structure consisted of some anticlastic surfaces. Form-finding of the inflatable moulds was conducted by the parametric tool “EasyForm” which is a self-programed plug-in in Grasshopper based on Vector Form Intrinsic Finite Element method.
In a low-temperature work environment (-10 ℃ and below), the ice shell structures were constructed on the inflatable moulds. The cellulose-water mixture was sprayed in thin layers continuously and uniformly in order to make the surface of a shell of cellulose-reinforced ice. The construction process is introduced detailedly in this paper.","Ice composite shell; form-finding; Vector Form Intrinsic Finite Element; construction; inflatable mould; cellulose-reinforced ice","en","conference paper","","","","","","","","","","","Structural Design & Mechanics","","",""
"uuid:4710d27e-a19a-42fb-8c6b-ef0d6c0bceaf","http://resolver.tudelft.nl/uuid:4710d27e-a19a-42fb-8c6b-ef0d6c0bceaf","Identification of the catenary structure wavelength using pantograph head acceleration measurements","Wang, H. (TU Delft Railway Engineering); Liu, Zhigang (Southwest Jiaotong University); Nunez, Alfredo (TU Delft Railway Engineering); Dollevoet, R.P.B.J. (TU Delft Railway Engineering)","","2017","For the condition monitoring of railway catenaries, the potential utilization of pantograph head (pan-head) vertical acceleration instead of pantograph-catenary contact force is discussed in this paper. In order to establish a baseline of the pan-head acceleration before it can be used for health condition monitoring, one of the essential frequency components, namely the catenary structure wavelength (CSW) is studied. Based on insitu measurements and feature analysis of the pan-head acceleration signal, an adaptive signal filtering approach is proposed to realize the identification of the CSWs. Preliminary results suggest that the CSWs contained in the pan-head acceleration can be reliably identified by the proposed filtering approach.","Adaptive signal filtering; Catenary health condition monitoring; Catenary structure wavelength; Identification; In-situ measurements; Pantograph head acceleration","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","Accepted Author Manuscript","","","","","Railway Engineering","","",""
"uuid:40e6a41f-757e-4960-be47-7d4bdb179804","http://resolver.tudelft.nl/uuid:40e6a41f-757e-4960-be47-7d4bdb179804","Comparison of Nested-Loop Rotors in Brushless Doubly-Fed Induction Machines","Wang, X. (TU Delft DC systems, Energy conversion & Storage); Liu, D. (TU Delft DC systems, Energy conversion & Storage); Lahaye, D.J.P. (TU Delft Numerical Analysis); Polinder, H. (TU Delft DC systems, Energy conversion & Storage); Ferreira, Jan Abraham (TU Delft Electrical Power Processing)","","2017","The brushless doubly-fed induction machine (DFIM) has great potential as a variable-speed generator for wind turbine applications. This special machine has a richer space-harmonic spectrum due to its special nested-loop rotor construction compared with conventional induction machines. It may result in higher iron losses, higher torque ripple and more time-harmonics adding to the grid total harmonic distortion (THD). This paper applies the 2D finite element (FE) model to investigate several different nested loop rotor constructions. It shows the outer loop makes more contribution to the torque while the inner loop plays a small role in the torque production. The most outer loop determines the overall THD level while the inner one has little influence on it. The THD could be reduced by increasing the number of the outer loops. More machine performances could be studied to derive more guidelines for designing the
middle loops.","permanent magnet machine; Concentrated winding; eddy current losses; experimental validation","en","conference paper","IEEE","","","","","","","","","","DC systems, Energy conversion & Storage","","",""
"uuid:4fa03e3d-11df-4323-b547-c96a62e4c6ee","http://resolver.tudelft.nl/uuid:4fa03e3d-11df-4323-b547-c96a62e4c6ee","Thermal Energy Recovery from Drinking Water","van der Hoek, J.P. (TU Delft Sanitary Engineering); Mol, S (Waternet); Ahmad, J.I. (TU Delft Sanitary Engineering); Liu, G. (TU Delft Sanitary Engineering); Medema, G.J. (TU Delft Sanitary Engineering)","Krope, J. (editor); Ghani Olabi, A. (editor); Goricanec, D. (editor); Bozicnik, S. (editor)","2017","","cold recovery; Greenhouse Gas emissions; drinking water; microbiological water quality; thermal energy","en","conference paper","University of Maribor Press","","","","","","","","","","Sanitary Engineering","","",""
"uuid:61610d9a-db9e-44ef-aa18-a4b178fb620c","http://resolver.tudelft.nl/uuid:61610d9a-db9e-44ef-aa18-a4b178fb620c","Up-Down Wavefields Reconstruction in Boreholes Using Single-Component Data","Liu, Y. (Norwegian University of Science and Technology (NTNU)); Arntsen, B (Norwegian University of Science and Technology (NTNU)); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2017","A standard procedure in processing vertical seismic profile (VSP) data is the separation of up-and downgoing wavefields. We show that the up-down wavefields in boreholes can be reconstructed using only singlecomponent borehole data, given that a full set of surface reflection data is also available. No medium parameters are required. The method is wave-equation based for a general inhomogeneous lossless medium with moderately curved interfaces. It relies on a focusing wavefield from the Marchenko method, which gives the recipe for finding this wavefield that satisfies certain focusing conditions in a reference medium. The up-down wavefields are then reconstructed at borehole positions using this focusing wavefields and the surface reflection response. We show that the method is applicable to boreholes with any general orientation. The requirement is that the source positions in the surface data are regularized to be the same as those in the borehole data, and that source deconvolution and surface multiple removal are applied for the surface data. Numerical results from a field in the North Sea are shown, and three different borehole geometries (horizontal, deviated and vertical) are tested. The result shows that the reconstructed up-down wavefields agree well with those by conventional separation methods.","","en","conference paper","EAGE","","","","","","","2018-06-01","","","Applied Geophysics and Petrophysics","","",""
"uuid:95a439c7-16a5-4308-9808-ced78d3febd3","http://resolver.tudelft.nl/uuid:95a439c7-16a5-4308-9808-ced78d3febd3","Experimental and computational investigation of gas diffusion in bitumen","Jing, R. (TU Delft Pavement Engineering); van Lent, Diederik (TNO); Kasbergen, C. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Erkens, S. (TU Delft Pavement Engineering)","","2017","When oxygen diffuses in a bituminous film, it also reacts, simultaneously, with the constituents of the bitumen and as such it is gradually depleted. This depletion process masks the characteristics of the actual diffusion process and complicates the determination of the diffusion coefficient needed for computation of oxygen concentration and its effects on bitumen degradation due to aging. In the present study, experiments were carried out to measure objectively oxygen absorption in bitumen at various temperatures independently of oxygen depletion phenomena. To achieve this, an improved version of van Oort’s test set up was utilized and oxygen was replaced by nitrogen. A Laplace transform based numerical technique was developed for processing the test results to determine the diffusion coefficients under various conditions. Once validated, they were used in finite element simulations to demonstrate the influence of time and temperature on gas diffusion and concentration in porous asphalt mixtures.","Gas diffusion; Laplace transform; theorem of Residues; finite element method; porous asphalt","en","conference paper","","","","","","","","","","","Pavement Engineering","","",""
"uuid:9437c6cd-f33f-4317-9020-82f05da5f1b6","http://resolver.tudelft.nl/uuid:9437c6cd-f33f-4317-9020-82f05da5f1b6","Intelligent condition monitoring of railway catenary systems: A Bayesian Network approach","Wang, H. (TU Delft Railway Engineering); Nunez, Alfredo (TU Delft Railway Engineering); Dollevoet, R.P.B.J. (TU Delft Railway Engineering); Liu, Zhigang (Southwest Jiaotong University); Chen, Junwen (Southwest Jiaotong University)","Spiryagin, Maksym (editor); Gordon, Timothy (editor); Cole, Colin (editor); McSweeney, Tim (editor)","2017","This study proposes a Bayesian network (BN) dedicated for the intelligent condition monitoring of railway catenary systems. It combines five types of measurements related to catenary condition, namely the contact wire stagger, contact wire height, pantograph head displacement, pantograph head vertical acceleration and pantograph-catenary contact force, as inputs
based on their physical meanings and correlations. It outputs an integrated indicator of catenary condition level. The BN parameters are learned from historical measurement data. Preliminary results shows the applicable ability of the BN to integrate multiple types of parameter while make sense of the output to facilitate maintenance decision making.","","en","conference paper","","","","","","","","","","","Railway Engineering","","",""
"uuid:720f2c1d-8556-4182-b679-7e00fe30e68a","http://resolver.tudelft.nl/uuid:720f2c1d-8556-4182-b679-7e00fe30e68a","Real Time Selective Detection of Experimentally Generated DC Series Arcs","Liu, Zhihao (Student TU Delft); Shekhar, A. (TU Delft DC systems, Energy conversion & Storage); Ramirez Elizondo, L.M. (TU Delft DC systems, Energy conversion & Storage); Bauer, P. (TU Delft DC systems, Energy conversion & Storage)","","2017","Localization of series arc faults in dc microgrids is an important requirement to guarantee operational safety and uninterrupted power to end users. In the previous EPE-ECCE proceeding, a theoretical proof was provided for the selective series arc detection using a novel algorithm. In the current paper, the concept is validated by showcasing real time localized detection when series arc is initiated between point of common coupling and one of the parallel loads. Experiments are repeated several times to gain statistical significance to account for the stochastic nature of the arcing phenomenon.","Resistance; Voltage measurement; Inductance; Real-time systems; Threshold voltage; Capacitance; Europe","en","conference paper","IEEE","","","","","","","","","","DC systems, Energy conversion & Storage","","",""
"uuid:5acc370a-435f-482a-9117-cb4bf6652d66","http://resolver.tudelft.nl/uuid:5acc370a-435f-482a-9117-cb4bf6652d66","Optimization of a geopolymer mixture for a reinforced cantilever concrete bench","Aldin, Zainab (Student TU Delft); Nedeljković, Marija (TU Delft Materials and Environment); Lukovic, M. (TU Delft Concrete Structures); Liu, Jiahua (Student TU Delft); Blom, Kees (Gemeente Rotterdam); Ye, G. (TU Delft Materials and Environment)","","2017","","","en","conference paper","","","","","","","","","","","Materials and Environment","","",""
"uuid:e50f6817-8e95-49db-b6e9-590fa571e547","http://resolver.tudelft.nl/uuid:e50f6817-8e95-49db-b6e9-590fa571e547","EasySRRobot: An Easy-to-Build Self-Reconfigurable Robot with Optimized Design","Yu, Minjing (Tsinghua University); Liu, Yong-Jin (Tsinghua University); Wang, C.C. (TU Delft Materials and Manufacturing)","","2017","Self-reconfigurable modular robots (SRRobot) that can change their shape and function in different environments according to different tasks have caught a lot of attention recently. Most existing prototypes use professional electronic components with relatively expensive cost and high barrier of fabrication. In this paper, we present a low-cost SRRobot with double-cube modules. Our system is easy-to-build even for novices as all electric components are off-the-shelf and the structural components in plastics are made by 3D printing. To have a better design of interior structures, we first construct a design space for all feasible solutions that satisfy the constraints of fabrication. Then, an optimized solution is found by an objective function incorporating the factors of space utilization, structural sound-ness and assembly complexity. Thirty EasySRRobot modules are manufactured and assembled. The functionality of our algorithm is demonstrated by comparing an optimized interior design with other two feasible designs and realizing different motions on an EasySRRobot with four modules.","self-reconfiguration; modular robot; optimal design","en","conference paper","IEEE","","","","","Accepted author manuscript","","","","","Materials and Manufacturing","","",""
"uuid:bc640f26-f059-4813-b08c-7df402387910","http://resolver.tudelft.nl/uuid:bc640f26-f059-4813-b08c-7df402387910","[POSTER] ChiroChroma: An Augmented Reality Game for the Assessment of Hand Motor Functionality","Goderie, C.J.M. (TU Delft Electrical Engineering, Mathematics and Computer Science); Alashrafov, R. (TU Delft Electrical Engineering, Mathematics and Computer Science); Jockin, Pieter; Liu, Lu; Liu, Xin; Cidota, M.A. (TU Delft System Engineering); Lukosch, S.G. (TU Delft System Engineering)","","2017","For a better understanding of how different diseases (e.g. neurovascular diseases, neurodegenerative diseases, and musculoskeletal pain conditions) affect human motor function, a uniform, standardized and objective evaluation is a desirable goal expressed within the clinical community. We explore the capabilities of an augmented reality (AR) game that uses free hand interaction to facilitate an objective assessment of the upper extremity motor dysfunction. First, the design process of the game and the system architecture are described. Second, a study about usability of the AR framework and game engagement is presented based on an experiment we conducted with five patients and ten healthy people. Lastly, a short analysis of the accuracy of the hand data when participants performed “fingers tapping” gesture is done. The results of the study show that even though users experienced the system as physically and mentally demanding, it was engaging enough to make them complete the game. The study also shows that hand data captured is accurate enough to allow a high degree (95%) of pinching gesture recognition.","Augmented Reality Games; Usability; Engagement; Upper Extremity Motor Dysfunction; Assessment; Parkinson's Disease; Stroke patients","en","conference paper","IEEE","","","","","","","","Electrical Engineering, Mathematics and Computer Science","","System Engineering","","",""
"uuid:7194f2b4-ca32-439b-9572-1076a4b42993","http://resolver.tudelft.nl/uuid:7194f2b4-ca32-439b-9572-1076a4b42993","Characterization of Series Arcs in LVdc Microgrids","Liu, Zhihao (Student TU Delft); Shekhar, A. (TU Delft DC systems, Energy conversion & Storage); Ramirez Elizondo, L.M. (TU Delft DC systems, Energy conversion & Storage); Bauer, P. (TU Delft DC systems, Energy conversion & Storage)","","2017","This paper provides an empirical study on series arc behavior in low voltage dc microgrids. The response of an R-L-C dc microgrid abstraction towards series arcs is studied experimentally for varying grid inductance, dc voltages, load capacitances and load currents. In order to account for the stochastic nature of arcs, experiments are repeated multiple times under similar conditions to gain statistical significance. Thereby, insight on percentage occurrence and burn time of initiated series arcs is provided. Load side voltage response is studied to gain insight on the expected peak drop and fall time. This empirical evidence was judged to be a necessary requirement in developing a novel series arc extinguishing method from load side power electronic devices.","arc characteristics; arcing; dc arc; dc microgrid; protection; series arc","en","conference paper","IEEE","","","","","","","","","","DC systems, Energy conversion & Storage","","",""
"uuid:95b0a12a-7cdb-41d5-8480-48bdb6904ab1","http://resolver.tudelft.nl/uuid:95b0a12a-7cdb-41d5-8480-48bdb6904ab1","Thick-level-set modeling of the dynamic double cantilever beam test","Liu, Y. (TU Delft Applied Mechanics); van der Meer, F.P. (TU Delft Applied Mechanics); Sluys, Lambertus J. (TU Delft Materials- Mechanics- Management & Design)","","2017","In this paper, the thick-level-set method is used to model stable and unstable (stick/slip) crack propagation in the dynamic double cantilever beam (DCB) test for unidirectional composite laminates. The thick-level-set method uses a predefined damage profile to describe the fracture process zone and allows
for accurate evaluation of the global energy release rate. A phenomenological model is introduced to calculate the crack speed as a function of the energy release rate. The potential capability of the proposed approach is demonstrated by simulating a series of dynamic DCB tests under variable test rates.","Thick level set; Dynamic fracture; Double cantilever beam; Crack arrest","en","conference paper","","","","","","","","","","Materials- Mechanics- Management & Design","Applied Mechanics","","",""
"uuid:5bb743ea-2396-4bef-8975-7b191d82b8fd","http://resolver.tudelft.nl/uuid:5bb743ea-2396-4bef-8975-7b191d82b8fd","Numerical evaluation of induction heating assisted compaction technology for low temperature asphalt pavement construction","Zhou, C. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Apostolidis, P. (TU Delft Pavement Engineering)","","2017","Low Temperature Asphalt (LTA) technologies are utilized in asphalt pavement industry to lower energy demands and greenhouse gas emission during mixing and construction processes. Although these technologies are currently available and hope to demonstrate similar performance with Hot Mix Asphalt (HMA) mixes, LTA shows more sensitive than HMA to temperature reduction during compaction and that will lead to inadequate compaction. Especially for Low Temperature Porous Asphalt (LTPA) mixes, the quick reduction of mix temperature is the main cause to poor pavements performance. The induction heating assisted compaction process appears to be an effective way to ameliorate compaction issues and to improve the compactability at lower temperatures. To design this process for LTA mixes, a numerical approach of combining the finite and the discrete element methods is presented in this paper. Porous asphalt concrete was the selected study material. The simulation process was divided into three steps: (i) temperature field prediction during induction heating, (ii) adjustment of asphalt mortar parameters and (iii) asphalt pavement compaction analysis. The effect of induction heating to asphalt compaction effectiveness, the tendency of mix density changing along with the increase of compactor passes and the influence of temperature on compaction at different locations in pavement were studied and discussed as well","Low temperature asphalt; Induction heating; Compaction; Porous asphalt; DEM; FEM","en","conference paper","Transportation Research Board (TRB)","","","","","","","","","","Pavement Engineering","","",""
"uuid:001395a8-3d12-4210-9922-c1d10111feee","http://resolver.tudelft.nl/uuid:001395a8-3d12-4210-9922-c1d10111feee","Towards the integration of indoorGML and indoorlocationGML for indoor applications","Liu, L. (TU Delft Urban Data Science); Zlatanova, S. (TU Delft Urban Data Science); Zhu, Q. (Southwest Jiaotong University); Li, K. (Pusan National University)","","2017","This paper introduces and compares two types of GML-based data standards for indoor location-based services, i.e., iIndoorGML and iIndoorLocationGML. By elaborating the advantages of the both standards and their data models, we conclude that the two data standards are complementary to each other. A jointed data model is presented to show the integration of the two standards. iIndoorGML can supply subdivision of building for data of iIndoorLocationGML, and the semantics of locations defined in iIndoorLocationGML can be added to iIndoorGML. By proposing two use cases, we take the initiative in attempting to combine the use of the two standards. The first case is to collect details from files of the two standards for an indoor path; the second one is to generate verbal directions for indoor guidance from files of the two standards. Some future work is given for further development, such as automatic integration of separate data from both standards.","Indoor Navigation; IndoorGML; IndoorLocationGML; Location-Based Services","en","conference paper","ISPRS","","","","","","","","","","Urban Data Science","","",""
"uuid:624e0a6f-854f-463b-be4c-62af81f363ad","http://resolver.tudelft.nl/uuid:624e0a6f-854f-463b-be4c-62af81f363ad","Finite Element Analysis and Experimental Validation of Eddy Current Losses in Permanent Magnet Machines with Fractional-Slot Concentrated Windings","Wang, X. (TU Delft DC systems, Energy conversion & Storage); Liu, D. (TU Delft DC systems, Energy conversion & Storage); Lahaye, D.J.P. (TU Delft Numerical Analysis); Polinder, H. (TU Delft DC systems, Energy conversion & Storage); Ferreira, Jan Abraham (TU Delft Electrical Power Processing)","","2016","Permanent-magnet machines with fractional slot concentrated windings are easy to manufacture. Their popularity therefore is steadily increasing. Without a proper design, however, the induced eddy-current losses in the solid rotor get rather high. The modeling and the prediction of eddy-current losses for these machines are thus very important during the design process. This paper focuses on the finite-element analysis and the experimental validation of eddy-current losses for this kind of machine with a small axial length. Two-dimensional and three-dimensional transient finite-element models are developed for computing the eddy-current losses. The rotor motion is taken into account using an Arbitrary Lagrangian-Eulerian formulation. The total iron losses are measured experimentally and a method to separate the rotor iron losses from the total iron losses is presented. The validation results show that the twodimensional finite-element model overestimates the losses due to the end-effects being neglected. The three-dimensional model agrees much better with the measurements in both no-load and on-load operations.","Concentrated winding; eddy current losses; experimental validation; permanent magnet machine","en","conference paper","IEEE","","","","","","","","","","DC systems, Energy conversion & Storage","","",""
"uuid:b70c44f1-afb3-4f5b-8390-92be89bf637b","http://resolver.tudelft.nl/uuid:b70c44f1-afb3-4f5b-8390-92be89bf637b","Topology Comparison of Superconducting Generators for 10-MW Direct-Drive Wind Turbines: Cost of Energy Based","Liu, D. (TU Delft DC systems, Energy conversion & Storage); Polinder, H. (TU Delft DC systems, Energy conversion & Storage); Abrahamsen, Asger Bech (Technical University of Denmark); Ferreira, Jan Abraham (TU Delft Electrical Power Processing)","","2016","Superconducting synchronous generators (SCSGs) are being proposed for 10-MW direct-drive wind turbines, because of their advantages of low weight and compactness. So far, however, there has not been a commonly accepted design philosophy of SCSGs and various possibilities with many tradeoffs remain for study. Partially SCSGs are considered a starting point since excessive AC losses in armature windings can be avoided. Many topologies can be applied to partially SCSGs and may significantly affect the performance indicators (PIs) of a wind turbine. Since cost of energy (CoE) is usually used as a key PI to evaluate the feasibility of an SCSG in wind turbine applications, this paper compares twelve topologies using MgB2 wires regarding the capital CoE as well as other resulting PIs. These topologies cover most possibilities for a radial-flux SCSG and four scenarios are investigated regarding the used MgB2 wire. The comparison results shows clear trends of these PIs over the twelve topologies and can be used as a reference for designing an SCSG for large direct-drive wind turbines.","","en","conference paper","","","","","","Activities/Press-Media?","","","","","DC systems, Energy conversion & Storage","","",""
"uuid:98088329-676a-4ba0-b76e-4dfb48e4eb4e","http://resolver.tudelft.nl/uuid:98088329-676a-4ba0-b76e-4dfb48e4eb4e","Short Circuits of a 10 MW High Temperature Superconducting Wind Turbine Generator","Song, X. (Technical University of Denmark); Polinder, H. (TU Delft DC systems, Energy conversion & Storage); Liu, D. (TU Delft DC systems, Energy conversion & Storage); Mijatovic, Nenad (Technical University of Denmark); Holbøll, Joachim (Technical University of Denmark); Jensen, Bogi Bech (University of the Faroe Islands)","","2016","Direct drive high temperature superconducting (HTS) wind turbine generators have been proposed to tackle challenges for ever increasing wind turbine ratings. Due to smaller reactances in HTS generators, higher fault currents and larger transient torques could occur if sudden short circuits happen at generator terminals. In this paper, a finite element model that couples magnetic fields and the generator’s equivalent circuits is developed to simulate short circuit faults. Afterwards, the model is used to study the transient performance of a 10 MW HTS wind turbine generator under four different short circuits, i.e., three-phase, phase-phase clear of earth, phase-phase-earth, and phase-earth. The stator current, fault torque, and field current under each short circuit scenario are examined. Also included are the forces experienced by the field winding under short circuits. The results show that the short circuits pose great challenges to the generator, and careful consideration should be given to protect the generator. The results presented in this paper would be beneficial to the design, operation and protection of an HTS wind turbine generator.","Finite element analysis; Force; High temperature superconducting generator; Short circuit; Transient","en","conference paper","IEEE","","","","","","","","","","DC systems, Energy conversion & Storage","","",""
"uuid:6dfb7570-0bf9-4bde-abd1-7aa1a021b551","http://resolver.tudelft.nl/uuid:6dfb7570-0bf9-4bde-abd1-7aa1a021b551","Quantification the filling of microcracks due to Autogenous self-healing in cement paste","Chen, J. (TU Delft Materials and Environment); Liu, Xian (Tongji University); Ye, G. (TU Delft Materials and Environment)","Azenha, M. (editor); Gabrijel, I. (editor); Schlicke, D. (editor); Kanstad, T. (editor); Mejlhede Jensen, O. (editor)","2016","Microcracks play vital roles in the prediction of the service life of concrete structure. Because microcracks in concrete structure are the preferential ingression channels for aggressive ions, e.g., chloride, sulphate, etc. However, microcracks have potentials to self-heal autogenously due to the continuous hydration of unhydrated cement, especially when ultra-/ high strength concrete is used. To quantify the autogenous self-healing effects of microcracks in cement paste, our experiment is designed to monitor the self-healing process of microcracks in cement paste continuously by using optical microscope. The healing products are quantified by image analysis with newly implemented software in MATLAB. The results indicate that the microcracks are not filled evenly along the crack length and most healing products are Ca(OH)2, which dissolve partly from the paste matrix and re-nucleate in the microcrack, in addition to its counterpart from the continuous hydration of unhydrated cement. Furthermore, the sample cracked at earlier age shows higher potential to heal, while the sample with smaller crack width experiences greater filling efficiency. The obtained autogenous selfhealing mechanism will be used in the future simulation.","Autogenous self-healing; Microcracks; Service life prediction; Image analysis","en","conference paper","RILEM Publications S.A.R.L.","","","","","","","","","","Materials and Environment","","",""
"uuid:d44c83be-6ea3-4650-9a09-a36302d7a77c","http://resolver.tudelft.nl/uuid:d44c83be-6ea3-4650-9a09-a36302d7a77c","Towards an Experimental Protocol for the Study of Induction Heating in Asphalt Mastics","Apostolidis, P. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering); van Bochove, G (Heijmans infra); van de Ven, Martin (TU Delft Pavement Engineering)","","2016","The development of asphalt mixtures with improved electrical and thermal properties is crucial in terms of producing suitable mixtures for the induction heating without losing their durability. The main scope of this research is to evaluate experimentally the impact of filler-sized electrically conductive additives on the induction heating efficiency and the rheological performance of asphalt mixtures. Within this framework, an experimental assessment protocol of structural and non-structural important parameters of induction heated asphalt mastics – asphalt mixtures without stone aggregates and sand – was developed. It was observed that by adding iron powder as filler-sized conductive additive to asphalt mastics the electrical and thermal properties improve. Moreover, the rheological investigations of different conductive asphalt mastics show the importance of adding iron powder after replacing the amount of mineral filler in order to maintain the workability of mastics. The micro-morphological observation of asphalt mastics using scanning electron microscopy illustrates the impact of filler-size particles – minerals and conductive additives – on the skeleton of asphalt mastics.","","en","conference paper","","","","","","","","","","","Pavement Engineering","","",""
"uuid:13d61a0b-b787-423e-9ca5-070a5807b2eb","http://resolver.tudelft.nl/uuid:13d61a0b-b787-423e-9ca5-070a5807b2eb","Investigation of Induction Heating in Asphalt Mortar: Numerical Approach","Apostolidis, P. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering); van de Ven, Martin (TU Delft Pavement Engineering); van Bochove, G (Heijmans infra)","","2016","The research reported in this paper focuses on utilization of advanced finite-element analyses (COMSOL) for the design and assessment of the induction heating capacity of asphalt mortar by adding electrically conductive additives (e.g., steel fibers), and to understand the factors that influence the mechanisms of induction heating in asphalt mixtures. In order to determine numerically the effective electrical and thermal properties of the conductive asphalt mortar with different volumes of steel fibers, 3D finite element meshes were generated by using X-ray images and utilized for calibration of the model parameters to perform a more realistic simulation of the asphalt mixture induction healing. The findings of this research are part of a study to provide an optimization method for the development of the necessary tools and equipment that will enable the implementation of induction technology for healing of asphalt concrete mixtures.","","en","conference paper","","","","","","","","","","","Pavement Engineering","","",""
"uuid:b02e528e-8aa4-4b39-9787-8b9900a858f8","http://resolver.tudelft.nl/uuid:b02e528e-8aa4-4b39-9787-8b9900a858f8","Advanced Experimental Evaluation of Asphalt Mortar for Induction Healing Purposes","Apostolidis, P. (TU Delft Pavement Engineering); Liu, X. (TU Delft Pavement Engineering); Scarpas, Athanasios (TU Delft Pavement Engineering); van Bochove, G (Heijmans infra); van de Ven, Martin (TU Delft Pavement Engineering)","","2016","This paper studied the induction heating and healing capacity of asphalt mortar by adding electrically conductive additives (e.g. iron powder and steel fibers), and examined the influence of different combinations of them on the mechanical response of asphalt mortars. Induction heating technique is this innovative asphalt pavement maintenance method that is applied to the conductive asphalt concrete mixtures in order to prevent the formation of macro-cracks by increasing locally the temperature of asphalt mixtures. It was found that increasing steel fiber content within the asphalt mortar the tensile strength and the fatigue life increased respectively. It was also proved that the conductive asphalt mortars with iron powder appeared improved mechanical response when steel fibers were added. Furthermore, it was observed that asphalt mortars containing a combination of additives – steel fibers and iron powder - demonstrate a better induction heating efficiency than mortars including only steel fibers. Finally, the induction healing capacity of conductive asphalt mortars is determined.","","en","conference paper","","","","","","","","","","","Pavement Engineering","","",""
"uuid:942520af-7469-4fff-8893-40e007f52496","http://resolver.tudelft.nl/uuid:942520af-7469-4fff-8893-40e007f52496","An experimental and modelling evaluation of the deformation and fracture of quasi-brittle reticulated vitreous carbon foam","Heard, P; Šavija, B. (TU Delft Materials and Environment); Liu, D; Smith, GE; Hallam, KR; Schlangen, E. (TU Delft Materials and Environment); Flewitt, P.E.J.","Gdoutos, Emmanuel E. (editor)","2016","In quasibrittle materials the addition of specific microstructural features such as porosity can lead to departure from linear elastic behaviour prior to maximum force, followed by graceful failure. A simple but extreme example is reticulated vitreous carbon foam, with its opencell structure of brittle ligaments connected in a threedimensional array. Tensile testing has been made on foams with various pore and ligament dimensions to provide a measure of forcedisplacement, combined with acoustic monitoring, and evaluation of the associated elastic moduli and fracture strengths. These tests provide insights into the mechanisms of quasibrittle failure. The results are explored by comparing with predictions from a microstructurebased finite beam element model. Inputs to the model are the elastic modulus and fracture strength of the individual ligaments of the foam measured at the micro lengthscale. Results are discussed with respect to the energy of fracture, the distribution and progression of fracture for individual ligaments.","","en","conference paper","","","","","","","","","","","Materials and Environment","","",""
"uuid:e80e4e04-70b1-4e5c-b36b-ce2238136d86","http://resolver.tudelft.nl/uuid:e80e4e04-70b1-4e5c-b36b-ce2238136d86","3D RANS simulations of shallow water effects on rudder hydrodynamic characteristics","Liu, J. (TU Delft Ship Design, Production and Operations); Hekkenberg, R.G. (TU Delft Ship Design, Production and Operations)","","2016","An accurate estimation of the rudder forces and moments is essential for manoeuvrability prediction. Previous research has shown that ships have different manoeuvring performance in deep and shallow water. Before considering the rudder’s contribution to shallow water manoeuvring, it is meaningful to analyse the shallow water effects on the rudder itself. In shallow water, the rudder gets close to the channel bottom. Therefore, mirror effects are expected, which may greatly affect the rudder effective aspect ratio and the generated rudder forces. Instead of high-cost model tests and time consuming full ship CFD simulations, this paper applies 3D RANS methods to analyse the shallow water effects on rudder hydrodynamic characteristics. 3D RANS simulations are carried out with a pressure-based coupled algorithm through ANSYS Fluent 16.2. The turbulence is simulated by a realisable k-e turbulence model. Based on a NACA 0020 profile, the method is validated through a comparison of the CFD results with the wind tunnel tests. Then, NACA 0020 spade rudders with geometric aspect ratios of 1.2 and 1.5 are tested with different tip clearance. Rudder lift and drag coefficients are generated to calculate the normal force coefficient for manoeuvring simulations. Finally, shallow water effects on rudder hydrodynamics are summarised.","rudder hydrodynamics; shallow water effect; 3D RANS simulations","en","conference paper","Harbin Engineering University","","","","","","","","","","Ship Design, Production and Operations","","",""
"uuid:41ce18cd-ebe9-410e-a979-6a56d7e05de2","http://resolver.tudelft.nl/uuid:41ce18cd-ebe9-410e-a979-6a56d7e05de2","Interaction effects on hydrodynamic characteristics of twin rudders","Liu, J. (TU Delft Ship Design, Production and Operations); Hekkenberg, R.G. (TU Delft Ship Design, Production and Operations)","","2016","In order to reach the required manoeuvrability, inland vessels often use twin rudders, but the interaction effects are poorly understood. To achieve a proper configuration, this paper applies 2D RANS simulations to analyse the interaction effects on the twin-rudder hydrodynamics. Various twin-rudder configurations with different profiles and spacing of the rudders are studied. RANS simulations are carried out with a k-w SST turbulence model and a pressure-based coupled algorithm. Commercial CFD package ANSYS Meshing and ANYSYS Fluent are applied as the mesh generator and the numerical solver. Series of NACA, IFS, and Wedge-tail profiles are tested and compared in various configurations. Finally, the interaction effects on twin-rudder hydrodynamic characteristics are summarised.","rudder hydrodynamic characteristics; rudder interactions; twin-rudder ships; Computational Fluid Dynamics","en","conference paper","Harbin Engineering University","","","","","","","","","","Ship Design, Production and Operations","","",""
"uuid:170cc1de-39a6-4906-ad7a-935382da4232","http://resolver.tudelft.nl/uuid:170cc1de-39a6-4906-ad7a-935382da4232","New method for discriminating 4D time shifts in the overburden and reservoirr","Liu, Yi (Norwegian University of Science and Technology (NTNU)); Arntsen, B (Norwegian University of Science and Technology (NTNU)); Landrö, M (Norwegian University of Science and Technology (NTNU)); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","Sicking, Charles (editor); Ferguson, John (editor)","2016","Understanding seismic changes in the subsurface is important for reservoir management and health, safety and environmental (HSE) issues. Typically the changes are interpreted based on the time shifts in seismic time-lapse (4D) data, where sources are at the surface and receivers are either at the surface or in a borehole. With these types of acquisition geometry, it is more straightforward to detect and interpret changes in the overburden, close to the source and receivers, than changes in the deeper part close to the reservoir, because the time shift is accumulative along its ray path from source to receiver. We propose a new method for reconstructing the reflection responses of the overburden and the reservoir, separately, for 4D time shift analysis. This method virtually moves sources and receivers to a horizontal borehole level, which enables a more direct interpretation of the time shifts to the changes close to the borehole, instead of to the surface. A realistic field model is used to demonstrate the method, and we observe a clear discrimination of the different time shifts in the overburden and reservoir, which is not obvious in the original datasets.","reconstruction; time-lapse; traveltime; downhole receivers; internal multiples","en","conference paper","SEG","","","","","","","","","","Applied Geophysics and Petrophysics","","",""
"uuid:d62f94d1-34bb-4dfb-9a6c-1b16e6899018","http://resolver.tudelft.nl/uuid:d62f94d1-34bb-4dfb-9a6c-1b16e6899018","Autoregressive Moving Average Graph Filter Design","Liu, J. (TU Delft Signal Processing Systems); Isufi, E. (TU Delft Signal Processing Systems); Leus, G.J.T. (TU Delft Signal Processing Systems)","Glineur, F. (editor); Louveaux, J. (editor)","2016","To accurately match a finite-impulse response (FIR) graph filter to a desired response, high filter orders are generally required leading to a high implementation cost. Autoregressive moving average (ARMA) graph filters can alleviate this problem but their design is more challenging. In this paper, we focus on ARMA graph filter design for a known graph. The fundamental aim of our ARMA design is to create a good match to the desired response but with less coefficients than a FIR filter. Our design methods are inspired by Prony’s method but using proper modifications to fit the design to the graph context. Compared with FIR graph filters, our ARMA graph filters show better results for the same number of coefficients.","","en","conference paper","Université Catholique de Louvain, Belgium","","","","","","","","","","Signal Processing Systems","","",""
"uuid:e8a97eba-97da-42ff-9488-136ca84a883a","http://resolver.tudelft.nl/uuid:e8a97eba-97da-42ff-9488-136ca84a883a","Influence of distance and incident angle on light intensities in intravascular optical coherence tomography pullback runs","Liu, Shengnan (Leiden University Medical Center); Eggermont, Jeroen (Leiden University Medical Center); Wolterbeek, Ron (Leiden University Medical Center); Lelieveldt, B.P.F. (TU Delft Pattern Recognition and Bioinformatics; Leiden University Medical Center); Dijkstra, J (Leiden University Medical Center)","Wook Kang, Hyun (editor); Tearney, Guillermo J. (editor); Gregory, Kenton W. (editor); Marcu, Laura (editor); Skala, Melissa C. (editor); Campagnola, Paul J. (editor); Choi, Bernard (editor); Kollias, Nikiforos (editor); Zeng, Haishan (editor); Mandelis, Andreas (editor); Wong, Brian J.F. (editor); Ilgner, Justus F. (editor)","2016","Intravascular optical coherence tomography (IVOCT) is an intravascular imaging modality which enables the visualization arterial structures at the micro-structural level. The interpretations of these structures is mainly on the basis of relative image intensities. However, even for homogeneous tissue light intensities can differ. In this study the incident light intensity is modeled to be related to the catheter position. Two factors, the distance between catheter and inner lumen wall as well as the incident angle of the light upon the lumen wall, are considered. A three-level hierarchical model is constructed to statistically validate this model to include the potential effect of different pullbacks and/or frame numbers. The model is solved using 169 images out of 9 pull-backs recorded with a St.Jude Medical IVOCT system. F-tests results indicate that both the distance and the incident angle contribute to the model statistically significantly with p < 0.001. Based on the results from the statistical analysis, a potential compensation method is introduced to normalize the IVOCT intensities for the catheter position effects and small shadows","angle of incidence; catheter position; compensation; distance; hierarchical linear regression; intravascular optical coherence tomography; IVOCT; statistical analysis","en","conference paper","SPIE","","","","","","","","","","Pattern Recognition and Bioinformatics","","",""
"uuid:ba10b1b8-8956-4a85-82fd-a1b8d59138dd","http://resolver.tudelft.nl/uuid:ba10b1b8-8956-4a85-82fd-a1b8d59138dd","A 2 × 2 array receiver at 1.4 THz based on HEB mixers and a Fourier phase grating local oscillator","Liu, X.X.; Hayton, D.J.; Luo, Y.C.; Wei, L.; Vercruyssen, N.; Gao, J.R.; Groppi, C.","","2015","We report on realization of a 2 × 2 NbN hot electron bolometer (HEB) array receiver using multiple local oscillator (LO) beams that are obtained from a Fourier phase grating mirror. The grating splits a 1.4 THz single beam into four uniform sub-beams. Two 50mm lenses are applied to collimate each beam in order to achieve a spacing of 12mm between them. The LO power in each beam is shown to be enough to fully pump the HEB mixer elements. The IV curves, noise temperature and IF bandwidth for each pixel is then characterized.","","en","conference paper","International Symposium on Space Terahertz Technology (ISSTT)","","","","","","","","Applied Sciences","QN/Quantum Nanoscience","","","",""
"uuid:37e6eb09-e9ef-4a5f-9d79-d1299bbd7af2","http://resolver.tudelft.nl/uuid:37e6eb09-e9ef-4a5f-9d79-d1299bbd7af2","Performance study of a double crossover for facing and trailing directions","Liu, X.; Markine, V.L.; Shevtsov, I.","","2015","This paper presented the performance study of two frogs in a double crossover in the railway network in the Netherlands. These frogs are located on the same track line. Each train passes through Frog 1 in the facing direction and Frog 2 in the trailing direction. Both frogs are monitored with ESAH-M crossing dynamic behaviour measurement tool and remote displacement measurement system Video Gauge. Results indicate that Frog 1 experiences high wheel/rail contact force (acceleration) and wear in Frog 2 develops fast. Frog 2 suffers from lack support of ballast, while the potential damage in Frog 1 is mainly related to the rail part.","","en","conference paper","CRC Press","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:6faf146e-fc15-4d00-a287-bba31442d9ca","http://resolver.tudelft.nl/uuid:6faf146e-fc15-4d00-a287-bba31442d9ca","Experimental study of key parameters investigation in turnout crossing degradation process","Liu, X.; Markine, V.L.; Shevtsov, I.; Dollevoet, R.P.B.J.","","2015","The continuous increasing demand of public transportation capacity requires the railway network operating in tight schedule. The high transporting volumes not only aggravate the degradation of railway infrastructure but also shorten the time for maintenance. Well-arranged infrastructure maintenance contributes to the budget reduction and reliability improvement. With the purpose of key parameters investigation in the turnout crossing degradation process, a series of subsequent measurements using instrumented crossing system (ESAH-M) on a 1:15 railway turnout at various stages were performed. The results indicate that wheel/rail impact area narrowed with deepened rail wear. This narrowing is a signal of rail damage. Frequency band pass filtered results describe the condition development of different structures in the turnout crossing section in the test period. Series of more systematic crossing measurements are in progress in a test section in the Netherlands. The ultimate purpose of this study is to form the crossing degradation function to be implemented in the structural health monitoring system (SHMS) for railway turnouts developed at the TU Delft.","railway turnout crossing; degradation process; field measurements; dynamic frequency response function; condition assessment","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:43151407-c489-4c91-83bb-20a64cba0e53","http://resolver.tudelft.nl/uuid:43151407-c489-4c91-83bb-20a64cba0e53","Near-infrared optical coherence tomography for the inspection of fiber composites","Liu, P.; Yao, L.; Groves, R.M.","","2015","Optical coherence tomography (OCT) is a non-invasive imaging method, which allows the econstruction of three dimensional depth-resolved images with microscale resolution. Originally developed for biomedical diagnostics, nowadays it also shows a high potential for applications in the field of non-destructive testing (NDT). This work demonstrates how OCT could help to investigate the delamination growth in fiber composites. A customized OCT system was built with a near-infrared light source with center wavelength at 1550 nm. It was used as an inline NDT tool to monitor the crack tips and image the crack surfaces within a glass fiber composite under static loading. For carbon fiber composites, although it is difficult to acquire the internal structures due to their opaque property, OCT can still work as a surface profilometer to reconstruct 3D crack surface profiles, providing substantial information for the study of crack growth in the composites.","","en","conference paper","DGZfP","","","","","","","","Aerospace Engineering","Aerospace Structures and Materials","","","",""
"uuid:64f2fc04-f957-410d-bc10-a7b285ef4f06","http://resolver.tudelft.nl/uuid:64f2fc04-f957-410d-bc10-a7b285ef4f06","Creating virtual receivers from drill-bit noise","Liu, Y.; Draganov, D.S.; Wapenaar, C.P.A.; Arntsen, B.","","2015","In the field of seismic interferometry using noise, surface waves and body waves between receivers have been retrieved by crosscorrelating recordings of uncorrelated noise sources to extract useful subsurface information. When the positions of the noise sources are known, inter-source interferometry can be applied to retrieve the wavefileds between sources, thus turning sources into virtual receivers. Previous applications of this form of interferometry assume impulsive point sources or transient sources with similar signatures. We investigate the requirements of applying inter-source seismic interferometry using drill-bit noise to retrieve the reflection responses at those positions. We show that an accurate estimate of the source function is essential for such application. The preprocessing involves using standard seismicwhile-drilling procedures, such as pilot crosscorrelation and pilot deconvolution to remove the drill-bit signatures in the data, and then applying crosscorrelation interferometry. Provided that pilot signals are reliable, drill-bit data can be redatumed from surface to the depth of boreholes using this inter-source interferometry approach without any velocity information of the medium. We show that a well-positioned image below the borehole can be obtained with just a simple velocity model using these reflection responses. We also discuss some of the practical hurdles that restrict its application offshore.","","en","conference paper","EAGE","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:1f58457d-799f-4d76-9269-416ae2556385","http://resolver.tudelft.nl/uuid:1f58457d-799f-4d76-9269-416ae2556385","Effect of hysteresis on the stability of an embankment under transient seepage","Liu, K.; Vardon, P.J.; Arnold, P.; Hicks, M.A.","","2015","Hysteresis is a well-known phenomenon that exists in the soil water retention behaviour of unsaturated soils. However, there is little research on the effects of hysteresis on slope stability. If included in slope stability analyses, commonly the suction in the unsaturated zone is taken as non-hysteretic. In this paper, the authors investigate the effect of hysteresis on the stability of an embankment under transient seepage. A scenario of water level fluctuation has been assessed, in which a cyclic external water level fluctuates between a low and high level. It was found that the factor of safety (FOS), the volumetric water content and the suction in the unsaturated zone are significantly affected by hysteresis. It was also found that, when the period of water level fluctuation in one cycle is relatively small, there is little difference in the FOS between the hysteretic case and non-hysteretic case. However, when the period exceeds a certain threshold value, significant differences between these two cases can be observed. Compared to the case in which hysteresis is considered, the FOS is higher in the case which does not consider hysteresis. This suggests that the non-hysteretic case may overestimate slope stability, leading to a potentially dangerous situation. Moreover, the period under which there emerge large differences between the hysteretic and non-hysteretic case is strongly related to the magnitude of hydraulic conductivity and the period of the cyclic water level fluctuation.","","en","conference paper","IOP Publishing","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:742d34f8-f9a1-4296-bd96-93b81e2ffc9c","http://resolver.tudelft.nl/uuid:742d34f8-f9a1-4296-bd96-93b81e2ffc9c","Impacts of rudder profiles on ship manoeuvrability","Liu, J.; Quadvlieg, F.; Hekkenberg, R.G.","","2015","The performance of a ship’s rudder largely determines its manoeuvrability, which includes turning ability, initial turning ability, yaw-checking ability and course-keeping ability. However, existing empirical formulas for rudder forces do not concern the rudder profile. This paper discusses the impacts of various rudder profiles on ship manoeuvrability. Instead of empirical formulas for rudder characteristics, Computational Fluid Dynamic methods (CFD) are applied to obtain lift and drag coefficients of five profiles. Then, the normal force coefficient of each profile is calculated and corrected for the aspect ratio. Commercial packages Pointwise and ANSYS ICEM generate the unstructured and structured mesh, respectively. ANSYS Fluent solves the Navier-Stokes equations. 2D steady-state viscous simulations of rudders in incompressible water are carried out with the k-w SST turbulence model. To test the impacts on manoeuvrability, a manoeuvring model is built in Python for the KVLCC2 tanker in deep water. Turning circle manoeuvres and zigzag manoeuvres are performed to compare the manoeuvring parameters. This paper concludes with insights into the impacts of rudder profiles on ship manoeuvrability.","ship rudders; RANS simulations; rudder profiles; ship manoeuvrability","en","conference paper","","","","","","","","","Mechanical, Maritime and Materials Engineering","Marine & Transport Technology","","","",""
"uuid:4095d737-9316-49d0-a949-e28d597fe9f1","http://resolver.tudelft.nl/uuid:4095d737-9316-49d0-a949-e28d597fe9f1","Optical coherence tomography complemented by hyperspectral imaging for the study of protective wood coatings","Dingemans, L.M.; Papadakis, V.; Liu, P.; Adam, A.J.L.; Groves, R.M.","","2015","Optical coherence tomography (OCT) is a contactless and non-destructive testing (NDT) technique based on lowcoherence interferometry. It has recently become a popular NDT-tool for evaluating cultural heritage. In this study, protective coatings on wood and their penetration into the wood structure were measured with a customized infrared fiber optic OCT instrument. In order to enhance the understanding of the OCT measurements of coatings on real wooden samples, an optimization of the measuring and analyzing methodology was performed by developing an averaging approach and by post-processing the data. The collected information was complemented by data obtained with hyperspectral imaging to allow data from local OCT A-scans to be used in mapping the coating thicknesses over larger areas.","optical coherence tomography; on-destructive testing; hyperspectral imaging; wood coatings; averaging; optimization; thickness mapping","en","conference paper","SPIE","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:15757723-3ac7-4188-a489-4218436e2aa0","http://resolver.tudelft.nl/uuid:15757723-3ac7-4188-a489-4218436e2aa0","Multi-scale characterization and modelling of damage evolution in nuclear Gilsocarbon graphite","Liu, D.; Heard, P.; Savija, B.; Smith, G.; Schlangen, E.; Flewitt, P.","","2015","In the present work, the microstructure and mechanical properties of Gilsocarbon graphite have been characterized over a range of length-scales. Optical imaging, combined with 3D X-ray computed tomography and 3D high-resolution tomography based on focus ion beam milling has been adopted for microstructural characterization. A range of small-scale mechanical testing approaches are applied including an in situ micro-cantilever technique based in a Dualbeam workstation. It was found that pores ranging in size from nanometers to tens of micrometers in diameter are present which modify the deformation and fracture characteristics of the material. This multi-scale mechanical testing approach revealed the significant change of mechanical properties, for example flexural strength, of this graphite over the length-scale from a micrometer to tens of centimeters. Such differences emphasize why input parameters to numerical models have to be undertaken at the appropriate length-scale to allow predictions of the deformation, fracture and the stochastic features of the strength of the graphite with the required confidence. Finally, the results from a multi-scale model demonstrated that these data derived from the micro-scale tests can be extrapolated, with high confidence, to large components with realistic dimensions.","x-ray tomography; fracture; nuclear materials","en","conference paper","Materials Research Society","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:5761199c-d383-4252-b06b-9248fadebccf","http://resolver.tudelft.nl/uuid:5761199c-d383-4252-b06b-9248fadebccf","Leveraging spatial model to improve indoor tracking","Liu, L.; Xu, W.; Penard, W.; Zlatanova, S.","","2015","In this paper, we leverage spatial model to process indoor localization results and then improve the track consisting of measured locations. We elaborate different parts of spatial model such as geometry, topology and semantics, and then present how they contribute to the processing of indoor tracks. The initial results of our experiment reveal that spatial model can support us to overcome problems such as tracks intersecting with obstacles and unstable shifts between two location measurements. In the future, we will investigate more exceptions of indoor tracking results and then develop additional spatial methods to reduce errors of indoor tracks.","spatial model; indoor tracking; semantics; topology","en","conference paper","International Society for Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Architecture and The Built Environment","Urbanism","","","",""
"uuid:5ceba8c6-2222-4081-8758-76bbd0740f70","http://resolver.tudelft.nl/uuid:5ceba8c6-2222-4081-8758-76bbd0740f70","Hydrologic and cryospheric processes observed from space","Menenti, M.; Li, X.; Wang, J.; Vereecken, H.; Li, J.; Mancini, M.; Liu, Q.; Jia, L.; Li, J.; Kuenzer, C.; Huang, S.; Yesou, H.; Wen, J.; Kerr, Y.; Cheng, X.; Gourmelen, N.; Ke, C.; Ludwig, R.; Lin, H.; Eineder, M.; Ma, Y.; Su, Z.B.","","2015","Ten Dragon 3 projects deal with hydrologic and cryosphere processes, with a focus on the Himalayas and Qinghai – Tibet Plateau, but not limited to that. At the 1st Dragon 3 Progress Symposium in 2013 a significant potential for a better and deeper integration appeared very clearly and we worked out an overview of the ten projects identifying specific issues and objectives shared by at least two projects. At the Mid Term Symposium in 2014 a joint session was held over two days. As regards cryospheric processes science highlights covered: Glacier flow velocity by optical and SAR features tracking and InSAR; Patterns in space and time of glacier flow velocity; Mass change estimated with DTM-s and altimetry; Reflectance and LST used to classify glacier surface and understand surface processes, Inventory and changes in the number and area of lakes in the Qinghai – Tibet Plateau 1970, 1990, 2000 and 2010; Deformation of permafrost along the Qinghai – Tibet railway. Highlights on hydrologic processes included: Global comparison of SMOS, ASCAT and ERA soil moisture data products; Relative deviations evaluated by climate zone; Soil moisture data products improved with ancillary data; Assimilation of FY - , TRMM and GPM precipitation data products in WRF; Improved algorithm and data products on fractional snow cover; Improvement of MODIS ET with assimilation of LST; TRMM data products evaluated in the Yangtze; Calibration of river basin models using LST; System to calibrate, correct and normalize (spatial, spectral) data collected by imaging spectral radiometers; Integration of data acquired by different sensors, e.g. ET Monitor with optical and microwave (SMOS, FY – 3) data; Hydrological data products used both for forcing and evaluation of Qinghai – Tibet Plateau hydrological model; Wetlands vulnerability assessed through changes in land cover 1987 – 2013; Multi incidence angle and multi – temporal SAR to monitor water extent. In the general session a proposal for a Dragon Water Cycle Initiative was presented.","terrestrial water cycle; multi sensor data products; glaciers; water resources; high elevation climate","en","conference paper","ISPRS","","","","","","","","Civil Engineering and Geosciences","Geoscience & Remote Sensing","","","",""
"uuid:cbf857e9-d94b-4803-83c0-99e5a1d7cb3e","http://resolver.tudelft.nl/uuid:cbf857e9-d94b-4803-83c0-99e5a1d7cb3e","Hydrodynamic Characteristics of Twin-Rudders at Small Attack Angles","Liu, J.; Hekkenberg, R.G.","","2015","RANS simulations are implemented to analyse the hydrodynamic characteristics of twin-rudders, i.e. Flat plate rudders, NACA rudders, and Wedge-tail rudders. The study mainly focuses on small attack angles. Results show that the NACA series is the most efficient profile while the Wedge-tail rudder has the highest rudder effectiveness.","2D rudder simulations; flat plate rudders; NACA rudders; wedge-tail rudders","en","conference paper","","","","","","","","","Mechanical, Maritime and Materials Engineering","Marine and Transport Technology","","","",""
"uuid:7a57993d-a5c1-422a-a7ae-cf23a8e10856","http://resolver.tudelft.nl/uuid:7a57993d-a5c1-422a-a7ae-cf23a8e10856","Fourier phase grating for THz multi-beam local oscillators","Luo, Y.C.; Liu, X.X.; Hayton, D.J.; Wei, L.; Gao, J.R.; Groppi, C.","","2015","A Fourier phase grating mirror will be applied to split a single, coherent terahertz source beam into multi-beams, which are spatially distributed as required for the local oscillator in an array receiver. We report on the simulation, design and fabrication of a Fourier phase grating at 1.25 THz for generating 2×2 beams, and the measurements at 1.39 THz as a proof of concept study. We find that the characteristics of the measured diffraction beams are in good agreement with the model. In addition, we present the simulation and design of a grating for 4×4 beams as required for the GUSSTO’s 4.7 THz local oscillator.","","en","conference paper","International Symposium on Space Terahertz Technology (ISSTT)","","","","","","","","Applied Sciences","QN/Quantum Nanoscience","","","",""
"uuid:c276d17d-34d1-4362-9052-99217bf08599","http://resolver.tudelft.nl/uuid:c276d17d-34d1-4362-9052-99217bf08599","Test method to assess membrane layers fatigue response on orthotropic steel bridge decks","Liu, X.; Tzimiris, G.; Li, J.; Scarpas, T.; Hofman, R.; Voskuilen, J.","","2015","In order to adequately characterize the fatigue response of the various membranes with surrounding multilayer surfacing layers on orthotropic steel decks and collect the necessary parameters for FE modeling, the details of the cyclic Membrane Adhesion Tester (MAT) are introduced. The fatigue damage in membrane interface is related to the amount of dissipated work computed by using the measurement of actuator load and piston deformation during the loading cycle. The dissipated work, which is equivalent to the lost part of the total potential energy of the membrane, has been utilized to explain the incremental damage during the testing. Furthermore, using the experimental data obtained from MAT, ranking of the bonding characteristics of various membrane products is demonstrated as well as the role of other influencing factors, such as the types of substrate and test temperatures.","membrane; orthotropic steel deck bridge; fatigue; dissipated energy; adhesive bonding 54 strength","en","conference paper","TRB","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:e054ee01-ac1a-45f6-ad08-ed49be009ef1","http://resolver.tudelft.nl/uuid:e054ee01-ac1a-45f6-ad08-ed49be009ef1","Identifying priority areas based on a thirteen years evolution of satisfaction with public transport and its determinants","Cats, O.; Abenoza, R.F.; Liu, C.; Susilo, Y.O.","","2015","","","en","conference paper","TRB","","","","","","","","Civil Engineering and Geosciences","Transport & Planning","","","",""
"uuid:a26e5c46-b6a2-4692-96bc-43656b9a2ad4","http://resolver.tudelft.nl/uuid:a26e5c46-b6a2-4692-96bc-43656b9a2ad4","Combining inter-source seismic interferometry and source-receiver interferometry for deep local imaging","Liu, Y.; Arntsen, B.; Wapenaar, C.P.A.; Van der Neut, J.R.","","2014","The virtual source method has been applied successfully to retrieve the impulse response between pairs of receivers in the subsurface. This method is further improved by an updown separation prior to the crosscorrelation to suppress the reflections from the overburden and the free surface. In a reversed situation where the sources are in the subsurface and receivers are on the surface, in principle, one can apply the same logic to retrieve the virtual response between pairs of sources by source-receiver reciprocity, turning the physical borehole sources into virtual receivers. However, since the up-down separation is not applicable on the source side, the simple crosscorrelation of the total fields results in spurious events due to the incomplete receiver coverage around the sources. We show with a numerical example that for this configuration of borehole sources and surface receivers, one can replace such an updown separation at the source side by that of the direct and reflected waves as a first order approximation. This procedure produces the virtual receiver data that is adequate for local imaging below the source depth and is completely independent of the accuracy of the overburden velocity model. We implement this inter-source type of interferometry by multidimensional deconvolution (MDD). Further, if the conventional surface survey data is available, we test the methodology from source-receiver interferometry (SRI) for this reverse configuration with borehole sources to retrieve the virtual receiver data with reflections coming from above, using also only the separation of the direct and reflected waves. By migrating the two sets of virtual receiver data, one can create a local image around the borehole sources in a deep area with better focusing and localization without a sophisticated velocity model.","","en","conference paper","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","","","","",""
"uuid:06abf5c2-f5f4-4d32-a941-0e015bf03d8b","http://resolver.tudelft.nl/uuid:06abf5c2-f5f4-4d32-a941-0e015bf03d8b","Metagenomic insights into the bio-functionality of 21 anaerobic biogas reactors (abstract)","Tao, Y.; Gao, D.W.; Wang, H.Y.; Zhang, X.; Ghasimi, S.M.D.; Ozgun, H.; Ersahin, M.E.; Zhou, Z.B.; Liu, G.; Temudo, M.F.; Kloek, J.; Spanjers, H.; De Kreuk, M.K.; Van Lier, J.B.","","2014","","","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Water Management","","","",""
"uuid:64e7724c-a053-4ba1-b926-aab9e0ea6ba2","http://resolver.tudelft.nl/uuid:64e7724c-a053-4ba1-b926-aab9e0ea6ba2","Design guidelines and empirical evaluation tools for inland ships","Rotteveel, E.; Hekkenberg, R.G.; Liu, J.","","2014","For inland ships, state-of-the-art hull form design is to a large extent based on experience, common sense, or adjusting previous designs. The idea therefore arises that further optimization is possible if the right knowledge is available. This knowledge is insufficiently available due to two main reasons. First, research into inland ship optimization is usually omitted from the design process due to the high cost compared to the design budget. This has led to a lack of fundamental knowledge about the complex hydrodynamics around the hull of an inland ship. Second, as a consequence of omitting optimization research, adequate empirical power prediction methods have not been developed for inland ships due to the lack of data. In the Top Ships project, effort is put in the development of an empirical method for inland ship power estimation as well as the derivation of design guidelines. Both should aid designers in the process of a new ship's design. The present paper gives an overview of available information from literature that aids to design of inland ships. Design guidelines and power prediction methods that relate to the design of a new inland ship are presented and discussed. The conclusions emerging from this review lead to the choice of focus in the Top Ships project. Therefore an introduction, the approach and intended results of this project are briefly presented as well.","inland ships; literature review; shallow water; ship resistance; inland ship improvements","en","conference paper","Budapest University of Technology and Economics","","","","","","","","Mechanical, Maritime and Materials Engineering","Marine and Transport Technology","","","",""
"uuid:41d55ad7-b6d1-45db-a6af-64f12efa045d","http://resolver.tudelft.nl/uuid:41d55ad7-b6d1-45db-a6af-64f12efa045d","A proposal for standard manoeuvres and parameters for the evaluation of inland ship manoeuvrability","Liu, J.; Hekkenberg, R.G.; Rotteveel, E.","","2014","Inland ship manoeuvrability has more complex features than that of sea-going ships due to constrains of inland waterways and complicated ship configurations. In order to clarify the complexity of manoeuvring, impact factors of navigation environment and ship particulars are first analysed to point out the determinants for evaluation. After reviewing existing standards of testing manoeuvres and criteria, it is concluded that there is a lack of knowledge to develop design guidance for manoeuvring in shallow/restricted water, which is the common sailing condition for inland vessels, making a proper evaluation more difficult. For the purpose of achieving more realistic judgement on manoeuvrability, benchmark manoeuvres are proposed for discussion. Conclusions are drawn on the need of validation for the effectiveness of testing manoeuvres and elaborate manoeuvring criteria for inland vessels.","inland vessel manoeuvrability criteria; standard ship manoeuvres; manoeuvring capacity evaluation","en","conference paper","Budapest University of Technology and Economics","","","","","","","","Mechanical, Maritime and Materials Engineering","Marine and Transport Technology","","","",""
"uuid:f9b8ba0d-c83d-4b1c-9450-ca1cc2ae8bcb","http://resolver.tudelft.nl/uuid:f9b8ba0d-c83d-4b1c-9450-ca1cc2ae8bcb","Turning subsurface noise sources into virtual receivers by multi-dimensional deconvolution","Liu, Y.; Wapenaar, C.P.A.; Arntsen, B.","","2014","The retrieval of the Green's functions between receiver pairs by multi-dimensional deconvolution can be extended to extract the impulse response between source pairs through source-receiver reciprocity. However in general, the procedure requires the separation of the outgoing and incoming wavefields at the sources, which reduces to the separation of the direct waves and the reflected waves in the absence of free-surface and inter-layer multiples. We show that in theory, for non-transient noise sources where the separation may not be obvious in the data domain, the separation can be achieved by time-windowing in an intermediate crosscorrelation step, which can be readily included in the MDD scheme. We illustrate the method with a synthetic model.","","en","conference paper","EAGE","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:6f2fe376-15f1-423b-b8a1-9699e41814a4","http://resolver.tudelft.nl/uuid:6f2fe376-15f1-423b-b8a1-9699e41814a4","Viscoelastic stress modeling in cementitious materials using constant viscoelastic hydration modulus","Hansen, W.; Liu, Z.; Koenders, E.A.B.","","2014","Viscoelastic stress modeling in ageing cementitious materials is of major importance in high performance concrete of low water cement ratio (e.g. w/c ~0.35) where crack resistance due to deformation restraint needs to be determined. Total stress analysis is complicated by the occurrence of internal stresses due to shrinkage, which requires estimating the stress relaxation effect from tensile creep. This study presents a new and direct methodology for viscoelastic stress analysis based on measurement of the viscoelastic hydration modulus. Autogenous shrinkage, if restrained, creates an internal tensile stress condition which is uniform within a cross section. Autogenous shrinkage stresses develop within the porous hydration products. They are compressive stresses and if restrained by reinforcement a net tensile stress develops. Results show that the viscoelastic hydration modulus is approximately 8000-9000 MPa and is a constant material property. Total stress analysis can now be separated into two components, an elastic stress based on the Young’s modulus (typically in the range of 28000-34000 MPa) and a viscoelastic (time-dependent) stress based on measurement of timedependent strains (creep and shrinkage). The importance of reducing paste content for shrinkage stress control is demonstrated using the Pickett’s model.","autogenous shrinkage; High Performance Concrete (HPC); shrinkage stresses; modeling viscoelastic effects","en","conference paper","DCMat Ageing Centre, Delft University of Technology","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:24edf1b1-8da7-4a96-b2b2-1d7f41756798","http://resolver.tudelft.nl/uuid:24edf1b1-8da7-4a96-b2b2-1d7f41756798","""Improved geometric network model"" (IGNM): A novel approach for deriving connectivity graphs for indoor navigation","Mortari, F.; Zlatanova, S.; Liu, L.; Clementini, E.","","2014","Over the past few years Personal Navigation Systems have become an established tool for route planning, but they are mainly designed for outdoor environments. Indoor navigation is still a challenging research area for several reasons: positioning is not very accurate, users can freely move between the interior boundaries of buildings, path network construction process may not be easy and straightforward due to complexity of indoor space configurations. Therefore the creation of a good network is essential for deriving overall connectivity of a building and for representing position of objects within the environment. This paper reviews current approaches to automatic derivation of route graphs for indoor navigation and discusses some of their limitations. Then, it introduces a novel algorithmic strategy for extracting a 3D connectivity graph for indoor navigation based on 2D floor plans.","indoor navigation; route graphs; Geometric Network Model; semantic building; path finding; 2D floor plan","en","conference paper","International Society for Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","Architecture and The Built Environment","OTB","","","",""
"uuid:3a7b769d-912a-4776-b29f-c03cec003e84","http://resolver.tudelft.nl/uuid:3a7b769d-912a-4776-b29f-c03cec003e84","Accelerated ageing protocols for (polymer modified) PA to obtain representative (rheological) properties, mimicking field aged materials","Mookhoek, S.D. (TNO); Liu, G. (TU Delft OLD Road and Railway Engineering); Erkens, S. (TU Delft Pavement Engineering); Giezen, C; Voskuilen, Jan (Ministry of Infrastructure and the Environment)","","2014","In this work ageing protocols for asphalt and mastics were developed and investigated; i.e representation of the field ageing and their acceleration degree. Here it was aimed to age laboratory prepared specimen analogous to naturally aged materials in the field and compare their material properties. Such simulation of ageing is of importance in order to potentially specify and objectively assess the properties of (novel) binders and asphaltic materials for Porous Aaphalt (PA). Hence, two ageing protocols were developed and investigated; one ageing protocol for asphalt mixtures and one for asphalt mastics. The rheological (DSR) properties of binders from the laboratory aged materials have been evaluated in comparison to binders from field aged specimen.","","en","conference paper","Delft University of Technology","","","","","","Campus only","","","","Pavement Engineering","","",""
"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:493d1089-c862-4cea-96b2-e4345cb41fe5","http://resolver.tudelft.nl/uuid:493d1089-c862-4cea-96b2-e4345cb41fe5","Inter-source seismic interferometry by multidimensional deconvolution (MDD) for borehole sources","Liu, Y.; Wapenaar, C.P.A.; Romdhane, A.","","2014","Seismic interferometry (SI) is usually implemented by crosscorrelation (CC) to retrieve the impulse response between pairs of receiver positions. An alternative approach by multidimensional deconvolution (MDD) has been developed and shown in various studies the potential to suppress artifacts due to irregular source distribution and intrinsic loss. Following previous theories on SI by MDD, we extend it to retrieve the impulse response between pairs of source positions by invoking source and receiver reciprocity. We verify the theory using a simple two-layered model and show that the retrieved response by MDD is more accurate than that by CC, and furthermore, it is free of free-surface multiples. We discuss the necessary pre-processing required for this method. This inter-source SI approach creates a virtual acquisition geometry with both borehole sources and receivers without the need to deploy receivers in the borehole, which might be of interest to applications such as seismic while drilling (SWD).","","en","conference paper","Chinese Petroleum Society / Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:b8dd2611-72f8-49c4-af00-a785c9dbab71","http://resolver.tudelft.nl/uuid:b8dd2611-72f8-49c4-af00-a785c9dbab71","BQC: A new multi-GNSS data quality checking toolkit","Liu, H.; Tang, G.; Imparato, D.; Cui, H.; Song, B.; Rizos, C.","","2014","Multi-GNSS networks, for example M-GEX and iGMAS, are set up and grow quickly with the development of new navigation systems and multi-GNSS receivers. It is unavoidable that GNSS signals are deteriorated by several error sources. Thus GNSS network operators, data users and receiver designers all require data quality checking (QC). However, few GNSS data QC software can process data of new navigation systems even modernized GPS signals. This paper introduces BQC, a multi-GNSS data QC toolkit which can process data of GPS/GLONASS/Galileo/Beidou recorded in RINEX version 2 or 3. Various QC outputs are written in QC report files as well as graphically displayed. Also in this paper, the cycle slip detection processing of BQC is emphasized as a key algorithm and compared with that of TEQC, the most widely-used GNSS data QC toolkit. The numerical results show that BQC reduces miss probability in cycle slip detection and repairs cycle slip effects on multipath sequences more reliable compared to TEQC.","","en","conference paper","Nederlands Instituut voor Navigatie","","","","","","","","Civil Engineering and Geosciences","Geoscience & Remote Sensing","","","",""
"uuid:01387120-a39a-477f-acea-e5b902b018fa","http://resolver.tudelft.nl/uuid:01387120-a39a-477f-acea-e5b902b018fa","Design study of a 10 MW MgB2 superconductor direct drive wind turbine generator","Abrahamsen, A.B.; Magnusson, N.; Liu, D.; Stehouwer, E.; Hendriks, B.; Polinder, H.","","2014","A superconducting direct drive generator based on field windings of MgB2 superconducting tape is proposed as a solution by mounting the generator in front of the blades using a king-pin nacelle design for offshore turbines with power ratings larger than 10 MW as investigated in the INNWIND.EU project.","superconducting generator; direct drive generator; offshore wind turbine; nacelle integration","en","conference paper","EWEA","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Electrical Sustainable Energy","","","",""
"uuid:1e09f575-f92d-4472-96b9-6cd8b5c523fa","http://resolver.tudelft.nl/uuid:1e09f575-f92d-4472-96b9-6cd8b5c523fa","Experimental study of membrane fatigue response for asphalt multisurfacing systems on orthotropic steel deck bridges","Liu, X.; Tzimiris, G.; Scarpas, T.; Hofman, R.; Voskuilen, J.","","2014","In order to adequately characterize the fatigue response of the various membranes with surrounding multilayer surfacing layers on orthotropic steel decks and collect the necessary parameters for FE modeling, the details of the cyclic Membrane Adhesion Tester (MAT) are introduced. The fatigue damage in membrane interface is related to the amount of dissipated work computed by using the measurement of actuator load and piston deformation during the loading cycle. The dissipated work, which is equivalent to the lost part of the total potential energy of the membrane, has been utilized to explain the incremental damage during the testing. Furthermore, using the experimental data obtained from MAT, ranking of the bonding characteristics of various membrane products is demonstrated as well as the role of other influencing factors, such as the types of substrate and test temperatures.","membrane; orthotropic steel deck bridge; fatigue; dissipated energy; adhesive bonding strength","en","conference paper","TRB","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:fabc0cb6-e868-4bf4-84c2-f45cfc7d6642","http://resolver.tudelft.nl/uuid:fabc0cb6-e868-4bf4-84c2-f45cfc7d6642","Design of an MgB2 race track coil for a wind generator pole demonstration","Abrahamsen, A.B.; Magnusson, N.; Jensen, B.B.; Liu, D.; Polinder, H.","","2014","An MgB2 race track coil intended for demonstrating a down scaled pole of a 10 MW direct drive wind turbine generator has been designed. The coil consists of 10 double pancake coils stacked into a race track coil with a cross section of 84 mm x 80 mm. The length of the straight section is 0.5 m and the diameter of the end sections is 0.3 m. Expanded to a straight section of 3.1 m it will produce about 1.5 T magnetic flux density in the air gap of the 10 MW 32 pole generator and about 3.0 T at the edge of the superconducting coil with an operation current density of the coil of 70 A/mm2.","","en","conference paper","IOP","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Electrical Sustainable Energy","","","",""
"uuid:d4f799db-2cb1-4643-8b82-2a490a8c1a90","http://resolver.tudelft.nl/uuid:d4f799db-2cb1-4643-8b82-2a490a8c1a90","Generating navigation models from existing building data","Liu, L.; Zlatanova, S.","","2013","Research on indoor navigation models mainly focuses on geometric and logical models .The models are enriched with specific semantic information which supports localisation, navigation and guidance. Geometric models provide information about the structural (physical) distribution of spaces in a building, while logical models indicate relationships (connectivity and adjacency) between the spaces. In many cases geometric models contain virtual subdivisions to identify smaller spaces which are of interest for navigation (e.g. reception area) or make use of different semantics. The geometric models are used as basis to automatically derive logical models. However, there is seldom reported research on how to automatically realize such geometric models from existing building data (as floor plans) or indoor standards (CityGML LOD4 or IFC). In this paper, we present our experiments on automatic creation of logical models from floor plans and CityGML LOD4. For the creation we adopt the Indoor Spatial Navigation Model (INSM) which is specifically designed to support indoor navigation. The semantic concepts in INSM differ from daily used notations of indoor spaces such as rooms and corridors but they facilitate automatic creation of logical models.","indoor navigation; Navigation Model Generation; building data; indoor modelling","en","conference paper","ISPRS","","","","","","","","OTB Research Institute for the Built Environment","OTB Research","","","",""
"uuid:42184015-8cac-4be2-8084-a221744d0452","http://resolver.tudelft.nl/uuid:42184015-8cac-4be2-8084-a221744d0452","Feasibility Study of a 10 MW MgB2 Fully Superconducting Generator for Offshore Wind Turbines","Kostopoulos, D.; Liu, D.; Genani, G.; Polinder, H.","","2013","Offshore wind is considered a vital component of the future large scale renewable generation portfolio. Intense R&D effort is occurring in both the technology and the supply chain aiming at cost reduction. The drivetrain of wind turbines is an area of continuous evolution with currently no one standard configuration in the industry. It is anticipated that in order to upscale offshore wind turbines in the 10+ MW power range innovation is necessary in this subsystem. A possible solution could be the adoption of superconductivity technology. The potential benefits are multiple comprising weight, dimension and cost reduction in both capital and operating costs. In this paper a rough analytical design is presented of an MgB2 fully superconducting wind turbine generator (WTG). An analytical current sheet distribution is adopted to calculate the magnetic field of the generator and a finite element method (FEM) analysis is used to verify the field calculation. The objective of this work is to assess the technical feasibility of this generator topology and attempt to extract more general conclusions regarding the potential application of superconducting drivetrains in offshore wind turbines.","","en","conference paper","European Wind Energy Association","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Electrical Sustainable Energy","","","",""
"uuid:dec73624-fb7f-4795-8d1d-a136d599356e","http://resolver.tudelft.nl/uuid:dec73624-fb7f-4795-8d1d-a136d599356e","The first engineered self-healing asphalt road: How is it performing?","Liu, Q.; Schlangen, H.E.J.G.; Van Bochove, G.","","2013","Porous asphalt shows excellent performance in both noise reduction and water drainage. Although porous asphalt has these great qualities, its service life is much shorter (sometimes only half) compared to dense graded asphalt roads. Ravelling, which is the loss of aggregate particles from the surface layer, is the main damage mechanism of porous asphalt surface wearing courses. In this research, an induction healing approach (namely, activating the healing process of asphalt concrete through induction heating) was developed to enhance the durability of the porous asphalt roads. Steel fibres are added to a porous asphalt mixture to make it electrically conductive and suitable for induction heating. When micro cracks are expected to occur in the asphalt mastic of the pavement, the temperature of the mastic can be increased locally by induction heating of the steel fibres so that porous asphalt concrete can repair itself and close the cracks through the high temperature healing of the bitumen (diffusion and flow). The closure of micro cracks will prevent the formation of macro cracks. In such a way, ravelling can be avoided or delayed in the end. The healing potential of porous asphalt concrete with steel wool fibre was also evaluated in this research with both cylinder and beam samples. Damaged porous asphalt concrete with steel wool fibre can greatly restore its stiffness, strength and fatigue life with induction heating, which proves that the healing capacity of porous asphalt concrete with steel wool fibre is enhanced by induction heating. The optimal induction heating temperature is 85 ºC for porous asphalt concrete to obtain the best healing rate. Reheating does not decrease the healing rate of porous asphalt concrete, which means that heating can be repeated when cracks appear again. To apply the induction healing technology in real porous asphalt road, a trial section was constructed on Dutch motorway A58 in December 2010. This trial section survived the past three winters perfectly. Experiments were done on the cores drilled from the trial section and the results coincided with those on the laboratory made samples. The field cores showed good particle loss resistance, high strength, good fatigue resistance and high induction healing capacity. Based on the laboratory experiments and field experiences, induction healing can be a very good approach to enhance the durability of porous asphalt pavement.","asphalt concrete; application; induction heating; steel-wool fibres","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:eae2517c-277f-4f63-b161-9e847f02b88b","http://resolver.tudelft.nl/uuid:eae2517c-277f-4f63-b161-9e847f02b88b","Self-healing supramolecular polymer nanocomposites","Liu, Z.; Besseling, N.A.M.; Mendes, E.; Picken, S.J.","","2013","Polyborosiloxanes (PBSs) are viscoelastic, transparent, colourless, self-healable polymer matrices, synthesized by reacting linear polydimethylsiloxanes (PDMSs) with boric acid (BA) above 150°C. BA takes part not only in cleaving the PDMS chains, but also contributes boronic-acid like moieties to the cleaved chain ends, which provide supramolecular self-healing capabilities. PBSs can be regarded as supramolecular elastomers, owing to the reversible cross links formed by the abundant hydroxyl groups. Therefore they are able to recover both the microscopic and macroscopic fractures intrinsically via hydrogen-bonds. Additionally, a glass transition temperature (Tg) as low as -90°C ensures chain mobility to PBSs molecules to heal cracks autonomously without extra heat supply. Compared to traditional carbon-based polymeric materials, PBSs provide a higher resistance to heat and light owing to the siloxane backbone. Upon increasing the degree of modification, PBSs get stronger on the one hand. However, PBSs also become less adhesive and start suffering from brittle fracture. Interestingly, the addition of nano-clay (Cloisite 30B) solves this problem. It does not make PBSs more brittle as it does in traditional thermal plastics. Instead, it renders PBSs ductile but strong. Comparing to PBSs, the PBSs/Cloisite 30B nanocomposites even exhibit an additional filler-induced mechanical relaxation at high frequency. This phenomenon implies that PBSs/Cloisite 30B nanocomposites can be applicable as self-healing shock absorber. Further investigations will be focusing on characterization of the selfhealing capacity, on strengthening the composites and on tuning the position of the filler-induced rheological response. Upon applying other (nano-sized) reinforcements, PBSs can be endowed with wide variety of targeted functionalities, for instance, stiffness by nano-clay; thermal conductivity by graphite or boron nitride; piezoelectric properties by lead zirconate titanate (PZT), etc. The presence of particles is also advantageous for the adhesive properties of the composites, because particles lower the number of hydrogen-bonds by, either isolating molecules or forming particle-molecule interaction.","polyborosiloxane (PBS); hydrogen-bonding; self-healing","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:5d9468d2-a745-426c-9db9-58cee8ae4f2e","http://resolver.tudelft.nl/uuid:5d9468d2-a745-426c-9db9-58cee8ae4f2e","Finite element of multilayer surfacing systems on orthotropic steel bridges","Li, J.; Liu, X.; Scarpas, A.; Tzimiris, G.","","2013","Light weight orthotropic steel bridge decks have been widely utilized for bridges in seismic zones, movable bridges and long span bridges. In the last three decades, severe problems were reported in relation to asphaltic surfacing materials on orthotropic steel deck bridges. Earlier investigations have shown that the bonding strength of membrane layers to the surrounding materials has a strong influence on the structural response of orthotropic steel bridge decks. The most important requirement for the application of membrane materials on orthotropic steel bridge decks is that the membrane adhesive layer shall be able to provide sufficient bond to the surrounding materials. The research aims on developing a FE tool to simulate and understand the performance of asphaltic surfacing structures, so as to improve the design of surfacings and increase their service life. In this paper, Finite Element (FE) simulations of Merwedebrug bridge with two membrane layers system are presented. The finite element system CAPA-3D developed at the Section of Structural Mechanics of TU Delft has been utilized as the numerical platform for this study. Due to the multilayer of the surfacing materials and geometrical complexity of the steel bridge, the FE model shows the in time development of strains and stresses inside the surfacing materials depends highly on the wheel loading frequency, wheel position, membrane bonding strength as well as thicknesses and characteristics of the surfacing layers. Emphasis is placed on the distribution of strains and the evolution of damage in surfacing layers of different cases. Recommendations of surfacing structures design on orthotropic steel bridges are given.","orthotropic steel deck bridges; FE simulation; multilayer sufacing systems; membranes","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:a4da6b47-e27d-4584-86d9-0ca329de0785","http://resolver.tudelft.nl/uuid:a4da6b47-e27d-4584-86d9-0ca329de0785","Experimental investigation of multilayer surfacing system on orthotropic steel bridge with the five-point bending test","Tzimiris, G.; Liu, X.; Scarpas, A.; Li, J.; Hofman, R.; Voskuilen, J.","","2013","Due to lightweight and flexibility, orthotropic steel deck bridges become popular the last decades but several problems were reported in relation to asphalt surfacing materials such as rutting, cracking, loss of bond between the surfacing system and steel deck. In the Netherlands a surfacing structure for orthotropic steel bridge decks mostly consists of five structural layers: top porous asphalt layer, guss asphalt layer, steel deck and two membrane layers. The five-point bending fatigue test is the standard device in France for asphalt concrete used on steel orthotropic deck bridges to perform the best asphalt mixture having a strong resistance to cracking. For the needs of this paper the 5 PBT was employed in order to evaluate the performance of the whole multilayer structure on steel deck and also to evaluate the mechanical properties of both top and bottom membrane and the influence they have on the structure. For the completion of the experimental investigation two types of specimen have been tested using the 5PBT set up. Displacement sensors have been used in order to detect the initiation of cracks where they are most likely to appear. Strain gauges have been used in order to monitor significant changes in strain on the Guss asphalt layer during the fatigue tests. Shear displacements between the asphalt layers are monitored and presented. It shows that the stiffness and the bonding characteristics of the intermediate membrane sheet as well as the wearing course behaviour seem to have great influence on the mechanical response of multilayer bridge surfacing system.","five-point bending test; orthotropic steel deck bridge; multilayer surfacing system","en","conference paper","Transportation Research Board","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:7e0d3746-42c3-4a32-aacd-003251609acb","http://resolver.tudelft.nl/uuid:7e0d3746-42c3-4a32-aacd-003251609acb","Development of test method for assessing the bonding characteristics of membrane layers in wearing course laid on orthotropic steel bridge decks","Liu, X.; Scarpas, A.; Li, J.; Tzimiris, G.; Hofman, R.; Voskuilen, J.","","2013","In order to adequately characterize the adhesive bonding strength of the various membranes with surrounding materials on orthotropic steel decks and collect the necessary parameters for FE modeling, details of the Membrane Adhesion Test (MAT) are introduced. Analytical constitutive relations of the MAT device have been derived using the same methodology as Williams (1997). Furthermore, using the experimental data obtained from MAT, ranking of the bonding characteristics of various membrane products is demonstrated as well as the role of other influencing factors, such as the types of substrate and test temperatures.","membrane; orthotropic steel deck bridge; adhesive bonding strength; finite element; strain energy release rate","en","conference paper","Transportation Research Board","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:1eb5e8b0-2460-4235-adf4-8d6a24cbe735","http://resolver.tudelft.nl/uuid:1eb5e8b0-2460-4235-adf4-8d6a24cbe735","Interactive Pong: Exploring Ways of User Inputs through Prototyping with Sensors","Liu, W.; Stappers, P.J.; Pasman, G.J.; Van der Helm, A.J.C.; Aprile, W.A.; Keller, I.","","2012","This study aimed to explore ways of user inputs through designing interactive game controllers with different type of sensor. From building four experiential prototypes on Pong, we learned to drive design by focusing on interaction qualities, which determine the use of sensors. We found that the interaction qualities together as a set offer a way to design aesthetics of behavior in interaction.","interactive pong; interaction qualities","en","conference paper","ACM","","","","","","","","Industrial Design Engineering","Industrial Design","","","",""
"uuid:bb12200e-b7c1-42f5-b4a4-7a7f13b2a159","http://resolver.tudelft.nl/uuid:bb12200e-b7c1-42f5-b4a4-7a7f13b2a159","Researching interaction guidelines - Mapping playful quality to design interactive products","Chen, Y.C.; Liu, W.","","2012","The interactions in IT supported activities in a Generation Y work context were studied and discussed, which general design guidelines have een revealed. However, further research about practical design guidelines hasn’t been performed. This study aims to serve as supplement of this part based on previous research. By applying contextual interviews of mapping interaction quality and Aesthetic Experience, some phenomena of interaction in work context has been revealed. By using sensitizing toolkits, we extract participants’ latent needs and expectation of future working types. In the end, practical design guidelines for designing playful interactions in work context are drawn. Designers could benefit from the result and utilize the guidelines, prototyping new interactive products. Meanwhile, researchers could apply or modify the sensitizing toolkits or sessions in order to come up with new insights for designing different interaction qualities","aesthetics of interaction, generation Y, interaction; quality, design guidelines","en","conference paper","Chalmers University of Technology","","","","","","","","Industrial Design Engineering","Industrial Design","","","",""
"uuid:d1b62cb8-5ffe-4459-9b18-1efc1f781ab8","http://resolver.tudelft.nl/uuid:d1b62cb8-5ffe-4459-9b18-1efc1f781ab8","Analytical study on the vibration response of curved track subjected to moving load","Li, K.; Liu, W.; Markine, V.L.; Ma, L.","","2012","","analytical solution, vibration response, curved track, moving load, transfer function","en","conference paper","China Railway Publishing House","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:1dd1bd48-6c4f-4389-9a4b-36730c4d2610","http://resolver.tudelft.nl/uuid:1dd1bd48-6c4f-4389-9a4b-36730c4d2610","State-of-art of asphalt surfacings on long-spanned orthotropic steel deck in China","Chen, X.; Liu, X.; Qian, Z.; Lei, Z.","","2012","Reliable and durable asphalt surfacing systems still remain to be desired for the long-spanned orthotropic steel bridges as the nationally and internationally reports on distresses in deck pavement. Based on ten-year research works, this paper has presented a brief review and discussion of the Chinese practices and experiences of deck pavement on long-spanned steel bridges, including issues of typical surfacing materials and their properties, main distresses in asphalt surfacing, and the basic characteristics of asphalt surfacing on orthotropic steel bridge decks. It is concluded that the behaviours of deck pavement on oithotropic steel bridge deck under truck load are complex contributed by geometric and material-dependent nonlinearity, coupling the global dynamic effects of the whole bridge systems. More efficient computational techniques are still desirable to couple global effects into local responses, to count the interfacial effects and interaction, and to evaluate the effect of predominant distress of fatigue cracking and de-bonding on the service life of this type of structure.","long-spanned steel bridge; orthotropic steel decks; asphalt surfacing system; local deflection behaviour; composite action; fatigue cracking","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:102b76a8-c9bf-40ff-bf3b-31191d107ae9","http://resolver.tudelft.nl/uuid:102b76a8-c9bf-40ff-bf3b-31191d107ae9","Application of MAT device to characterize the adhesive bonding strength of membrane in orthotropic steel deck bridges","Liu, X.; Scarpas, A.; Li, J.; Tzimiris, G.","","2012","In order to characterize adequately the adhesive bonding strength of the various membranes with surrounding materials on orthotropic steel decks and collect the necessary parameters for FE modeling, details of the Membrane Adhesion Test (MAT) have been introduced. Analytical constitutive relations of MAT device have been derived on the basis of Williams (1997). Furthermore, on the basis of experimental data obtained from MAT, ranking of the bonding characteristics of various membrane products is demonstrated as well as the role of other influencing factors, such as the types of substrate and test temperatures.","membrane; orthotropic steel deck bridge; adhesive bonding strength; finite element; strain energy release rate","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:04a9ffb5-8e05-447f-94de-5e589ebfbb26","http://resolver.tudelft.nl/uuid:04a9ffb5-8e05-447f-94de-5e589ebfbb26","Advanced numerical study of the response of orthotropic steel deck bridge with two membrane layers system","Li, J.; Liu, X.; Scarpas, A.; Tzimiris, G.","","2012","In the Netherlands an asphaltic surfacing structure for orthotropic steel bridge decks mostly consists of two structural layers. The upper layer consists of Porous Asphalt (PA) because of reasons related to noise hindrance. For the lower layer a choice between Mastic Asphalt (MA) or Guss Asphalt (GA), can be made. In this paper, a typical Dutch steel bridge deck surfacing system is simulated by means of the three-dimensional fmite element system CAPA 3D. Special attention is given to the structural distress phenomena and the parameters that influenced them. The FE model shows the distribution of strains and stresses inside the surfacing materials depends highly on the wheel load level, wheel load frequency, wheel position, membrane bonding strength as well as the thicknesses and the characteristics of the surfacing layers.","orthotropic steel bridge; membrane; surfacing; finite element","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:ebc6e80e-3c9e-46a5-80be-c729524dd4f4","http://resolver.tudelft.nl/uuid:ebc6e80e-3c9e-46a5-80be-c729524dd4f4","Cryogenic suction pump mechanism for combined salt-and frost exposure","Borgnakke, C.; Hansen, W.; Kang, Y.; Liu, Z.; Koenders, E.A.B.","","2012","Freezing of water can be explained by the thermodynamic properties of the water due to the influence of temperature, pressure and special effects such as surface tension and salt solution. Gibbs free energy curves for ice and pore liquid containing different concentrations of NaCl (0-6%) are presented. These curves explain the onset of freezing in pores when the energy level for solid ice and pore liquid containing salt are equal. Upon further cooling a nonequilibrium condition develops since the Gibbs function for pure ice is less than the Gibbs function for the liquid. The theory also explains why ice nucleation is developing in the largest pores containing liquid, including air-voids. Below the nucleation temperature, a vacuum with low partial pressure of the water develops around the ice which starts a cryogenic suction pump. For a closed system (i.e. no external liquid) partial pore-drying develops leading to specimen shrinkage. In air-entrained concrete the ice growth may be accommodated within the pore system without structural damage. In the case external liquid is present, such as when the surface contains a salt solution, pore suction attracts surface liquid, and additional ice growth may not be accommodated within the pore system. Thus, a net expansion occurs. Frost expansion due to crystal growth is time-dependent and progresses as long as liquid is available and until thermodynamic equilibrium is re-established at a given temperature.","cryogenic suction; frost expansion; Gibbs-free energy; salt frost attack","","conference paper","RILEM Publications","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:0012bc0e-0edc-406d-9bcd-01a57c77e0d1","http://resolver.tudelft.nl/uuid:0012bc0e-0edc-406d-9bcd-01a57c77e0d1","Studying the relative impact of ghosting and noise on the perceived quality of MR images","Liu, H.; Koonen, J.; Fuderer, M.; Heynderickx, I.","","2012","In current magnetic resonance (MR) imaging systems, design choices are confronted with a trade-off between structured (i.e. artifacts) and unstructured noise. The impact of both types of noise on perceived image quality, however, is so far unknown, while this knowledge would be highly beneficial for further improvement of MR imaging systems. In this paper, we investigate how ghosting artifacts (i.e. structured noise) and random noise, applied at the same energy level in the distortion, affect the perceived quality of MR images. To this end, a perception experiment is conducted with human observers rating the quality of a set of images, distorted with various levels of ghosting and noise. To also understand the influence of professional expertise on the image quality assessment task, two groups of observers with different levels of medical imaging experience participated in the experiment: one group contained fifteen clinical scientists or application specialists, and the other group contained eighteen naïve observers. Experimental results indicate that experts and naïve observers differently assess the quality of MR images degraded with ghosting/noise. Naïve observers consistently rate images degraded with ghosting higher than images degraded with noise, independent of the energy level of the distortion, and of the image content. For experts, the relative impact of ghosting and noise on perceived quality tends to depend on the energy level of the distortion and on the image content, but overall the energy of the distortion is a promising metric to predict perceived image quality","MRI, perceived image quality, ghosting, noise, human visual system","en","conference paper","SPIE (International Society for Optical Engineering)","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Intelligent Systems","","","",""
"uuid:26d5e16d-b45e-4a0d-b61c-55bf23750ea1","http://resolver.tudelft.nl/uuid:26d5e16d-b45e-4a0d-b61c-55bf23750ea1","The integration of transportation with the energy system in China","Lund, H.; Liu, W.; Beella, S.K.; Brezet, J.C.","","2011","","","en","conference paper","","","","","","","","","Industrial Design Engineering","Design Engineering","","","",""
"uuid:28f7ef2e-d919-4e06-8c50-5f1fe133a44c","http://resolver.tudelft.nl/uuid:28f7ef2e-d919-4e06-8c50-5f1fe133a44c","Highway A58: The first engineered self healing asphalt road (abstract)","Schlangen, H.E.J.G.; Garica, A.; Van de Ven, M.F.C.; Van Bochove, G.; Van Montfort, J.; Liu, Q.","","2011","","self-healing; asphalt; road; application; induction; steelwool","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:95854074-fe4a-4c32-85af-82068a92a0f8","http://resolver.tudelft.nl/uuid:95854074-fe4a-4c32-85af-82068a92a0f8","Self-healing supramolecular polymer and polymer nanocomposites (poster abstract)","Liu, Z.; Besseling, N.A.M.; Mendes, E.; Picken, S.J.","","2011","","self-healing; supramolecular polymers; nanocomposite; mechanical testing","en","conference paper","","","","","","","","","Applied Sciences","ChemE/Chemical Engineering","","","",""
"uuid:de84a1c2-6596-4888-a0dd-898886e1f48f","http://resolver.tudelft.nl/uuid:de84a1c2-6596-4888-a0dd-898886e1f48f","A ""door-to-door"" path-finding approach for indoor navigation","Liu, L.; Zlatanova, S.","","2011","Indoor navigation is gaining an increasing interest among researchers in many domains. In many cases users need to orient quickly in complex environments, which is not always the target of current routing algorithms. The paper reviews current indoor path-finding approaches and discusses some of the limitations. In order to support a natural movement in buildings, typically for emergencies, we purpose a new indoor path-finding approach, that is, the “door-to-door” approach. We present an algorithm, which is applied to 2D floor plan of buildings with complex indoor structure. The algorithm consists of two-level routing: one is to get coarse route between rooms, and the other one is applied to single rooms to acquire the detailed route. Ultimately, several instances are given to illustrate advantages and feasibility of the door-to-door approach. From the test results it is evident this algorithm runs well even on quite complex floor plans. The paper concludes with a discussion of future work, which is to extend the routing approach into 3D, i.e. considering the vertical direction, indoor obstacles and path-finding in 3D scenarios.","indoor navigation; door-to-door navigation; path-finding; 2D floor plan; semantic building model","en","conference paper","International Society for Photogrammetry and Remote Sensing (ISPRS)","","","","","","","","OTB Research Institute for the Built Environment","OTB Research","","","",""
"uuid:e827dc6e-1020-4205-9b58-754a36454f66","http://resolver.tudelft.nl/uuid:e827dc6e-1020-4205-9b58-754a36454f66","Design research on business models in home healthcare","Simonse, LWL (TU Delft OLD Management and Organisation); Zonneland, J (External organisation); Liu, KQ (External organisation); Govers, F (External organisation); Vincent, R (External organisation); Laban, V (External organisation); Jensen, MG (External organisation); van Roest, I (External organisation); Hulsebosch, M (External organisation); Hibolling, S (External organisation); Voorend, M (External organisation)","Jun, C (editor); Lockwood, T (editor); Liu, JK (editor); Wang, S (editor); Song, Q (editor); Siu, N (editor); Lee, A (editor)","2011","In Home Healthcare, a huge number of telemonitoring pilots have been executed. Positive indications suggest reduction of health problems and support in helping patients to gain control. For healthcare providers, significantreductions in healthcare costs have been estimated. However,” despite this large amount of pilot studies and the positive indications of benefits, there is only minor use of these telemonitoring systems outside research projects”.Gruber ea.(2009) identified a major innovation barrier for the diffusion of telemonitoring solutions to health care providers: “Unclear business models and high costs of change for the health providers”. Traditional businessmodels of the healthcare providers seem not to fit with the telemonitoring solutions. We started a design research study to investigate the business model designs of home healthcare services. We used an inductive researchapproach by in-depth qualitative analysis grounded in telemonitoring pilot studies. We first build our research on the four box framework of business model designs (ea. Johnson ea. 2008, Amit & Zott, 2009). Then we exploredhome healthcare services in the Netherlands and China. In the Netherlands we collected data from different actor perspectives (#32). In Eastern China we collected data from end users (#8) and compared this to an end user groupsin the Netherlands. These findings results in an overview of insights for business models in home health care.","","en","conference paper","Tsinghua-DMI","","","","","","Campus only","","","","OLD Management and Organisation","","",""
"uuid:d1579a9e-85e2-455c-8587-c531500922e9","http://resolver.tudelft.nl/uuid:d1579a9e-85e2-455c-8587-c531500922e9","Issues in the design of a no-reference metric for perceived blur","Liu, H.; Heynderickx, I.","","2010","Developing an objective metric, which automatically quantifies perceived image quality degradation induced by blur, is highly beneficial for current digital imaging systems. In many applications, these objective metrics need to be of the noreference (NR) type, which implies that quality prediction is based on the distorted image only. Recent progress in the development of a NR blur metric is evident from many promising methods reported in the literature. However, there is still room for improvement in the design of a NR metric that reliably predicts the extent to which humans perceive blur. In this paper, we address some important issues relevant to the design as well as the application of a NR blur metric. Its purpose is not to describe a particular metric, but rather to explain current concerns and difficulties in this field, and to outline how these issues may be accounted for in the design of future metrics.","image quality assessment, objective metric, perceived blur, edge, visual attention","en","conference paper","SPIE","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Mediamatics","","","",""
"uuid:924f8c26-5f52-44cd-84eb-ca0b339d0e87","http://resolver.tudelft.nl/uuid:924f8c26-5f52-44cd-84eb-ca0b339d0e87","A Research on the Transformation of Urban Form And Dynamics of Xiguan Area, Guangzhou","Tai, Y.; Liu, Y.","","2010","This paper mainly uses the method of Urban Morphology to study the transformation process of urban form of Xiguan historical district in Guangzhou, P.R.China. The paper tries to analyze the transformation process through studying the background of politics, economy, society, culture and natural condition of Xiguan area. It further discusses the structural feature and transformation rule, as well as analyzes the hidden dynamics. Considering time as the main factor, the paper mainly focuses on two aspects—form elements and dynamics, trying to study the relation between each other. The paper aims at concluding the overall transformation feature and rule of Xiguan area and bringing up some perspectives on the protection and continuity of traditional urban fabric and culture in the process of urban renewal. The body of this paper is organized through tracing the transformation of urban form in different periods of time. First, to study the foundation of form transformation through demonstrating the construction background of Xiguan area before Qing Dynasty; Second, to discuss separately the form feature of Qing Dynasty, the period of the Republic of China and the period after the foundation of New China. The form feature is mainly analyzed in several aspects as the street feature, property plot, building type, land use and street space; Finally, to summarize the transformation rule on the basis of overall analysis of transformation feature of Xiguan area, and then to conclude the main dynamics of form transformation, as well as to discuss the practical significance for the protection of Xiguan historical district and urban renewal.","Guangzhou Xiguan; urban form; transformation; dynamics","en","conference paper","ISUF","","","","","","","","Architecture and The Built Environment","Urbanism","","","",""
"uuid:ef511dec-c68d-4104-9861-b3ddc25b14d3","http://resolver.tudelft.nl/uuid:ef511dec-c68d-4104-9861-b3ddc25b14d3","A CMOS 128-APS linear array integrated with a LVOF for highsensitivity and high-resolution micro-spectrophotometry","Liu, C.; Emadi, A.; Wu, H.; De Graaf, G.; Wolffenbuttel, R.F.","","2010","A linear array of 128 Active Pixel Sensors has been developed in standard CMOS technology and a Linear Variable Optical Filter (LVOF) is added using CMOS-compatible post-process, resulting in a single chip highly-integrated highresolution microspectrometer. The optical requirements imposed by the LVOF result in photodetectors with small pitch and large length in the direction normal to the dispersed spectrum (7.2?m×300?m). The specific characteristics of the readout are the small pitch, low optical signals (typically a photocurrent of 100fA~1pA) and a much longer integration time as compared to regular video (typically 100?s~63s). These characteristics enable a very different trade-off between SNR and integration time and IC-compatibility. The system discussed in this paper operates in the visible part of the spectrum. The prototype is fabricated in the AMIS 0.35?m A/D CMOS technology.","Capacitive transimpedance amplifier; correlated double sampling; active pixel sensor; IC-compatible microspectrometers; LVOF; variable integration time","en","conference paper","SPIE","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Department of ME/EI","","","",""
"uuid:b79a916d-2019-4d96-b18a-21e93d7fe323","http://resolver.tudelft.nl/uuid:b79a916d-2019-4d96-b18a-21e93d7fe323","No-Reference image quality assessment based on localized gradient statistics: Application to JPEG and JPEG2000","Liu, H.; Redi, J.; Alers, H.; Zunino, R.; Heyndrinckx, I.","","2010","","image quality assessment; objective metric; JPEG; JPEG 2000; neural network","en","conference paper","SPIE","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Man-Machine Interaction","","","",""
"uuid:9b4e0a42-a6a5-45e8-a67b-12cd31040d33","http://resolver.tudelft.nl/uuid:9b4e0a42-a6a5-45e8-a67b-12cd31040d33","Quantum optics with single nanowire quantum dots","Akopian, N.; Van Weert, M.; Van Kouwen, M.; Algra, R.; Liu, L.; Patriarche, G.; Harmand, J.C.; Bakkers, E.; Kouwenhoven, L.; Zwiller, V.","","2010","In this paper we present our recent developments in control and manipulation of individual spins and photons in a single nanowire quantum dot. Specific examples include demonstration of optical excitation of single spin states, charge tunable quantum devices and single photon sources. We will also discuss our recent discovery of a new type of charge confinement – crystal phase quantum dots. They are formed from the same material with different crystal structure, and today can only be realized in nanowires","nanowires; quantum dots; crystal phase","en","conference paper","SPIE","","","","","","","","Applied Sciences","Kavli Institute of Nanoscience","","","",""
"uuid:4125c809-f46f-4f2f-9b27-934dca20f353","http://resolver.tudelft.nl/uuid:4125c809-f46f-4f2f-9b27-934dca20f353","Studying the effect of optimizing the image quality in saliency regions at the expense of background content","Alers, H.; Liu, H.; Redi, J.; Heynderickx, I.","","2010","Manufacturers of commercial display devices continuously try to improve the perceived image quality of their products. By applying some post processing techniques on the incoming image signal, they aim to enhance the quality level perceived by the viewer. Applying such techniques may cause side effects on different portions of the processed image. In order to apply these techniques effectively to improve the overall quality, it is vital to understand how important quality is for different parts of the image. To study this effect, a three-phase experiment was conducted where observers were asked to score images which had different levels of quality in their saliency regions than in the background areas. The results show that the saliency area has a greater effect on the overall quality of the image than the background. This effect increases with the increasing quality difference between the two regions. It is, therefore, important to take this effect into consideration when trying to enhance the appearance of specific image regions.","image quality; saliency; region of interest; eye tracking","en","conference paper","SPIE","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Man-Machine Interaction","","","",""
"uuid:bd1cbe43-3abe-4865-bccf-e249340c5547","http://resolver.tudelft.nl/uuid:bd1cbe43-3abe-4865-bccf-e249340c5547","Comparing subjective image quality measurement methods for the creation of public databases","Redi, J.; Liu, H.; Alers, H.; Zunino, R.; Heynderickx, I.","","2010","","image quality; subjective quality assessment; psychometrics; single stimulus; quality ruler","en","conference paper","SPIE","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Man-Machine Interaction","","","",""
"uuid:03ed744e-d656-4f7c-b2bc-7bc8567f35de","http://resolver.tudelft.nl/uuid:03ed744e-d656-4f7c-b2bc-7bc8567f35de","InSAR based validation of MERIS IWV cloud gap filling using GPS IWV","Lindenbergh, R.C.; Liu, S.; Hanssen, R.; De Haan, S.; Van der Marel, H.","","2009","High spatial resolution integrated water vapor (IWV) estimates are available from the MERIS spectrometer on board of Envisat. Unfortunately cloud cover results in loss of a large amount of MERIS IWV pixels. Here methods are presented for filling cloud gaps in MERIS IWV scenes, first, by directly interpolating remaining pixels not affected by clouds, and second, by fusion with cloud insensitive IWV observations from ground stations of the GPS network. Results are validated by independent IWV estimates obtained from suited SAR interferograms. The results indicate that the procedure works mathematically in a correct way, but that the physical application of the results is strongly hampered by MERIS pixels affected by not automatically detected clouds.","","en","conference paper","","","","","","","","","Aerospace Engineering","Remote Sensing","","","",""
"uuid:40b0381f-684a-4a3a-ac3e-02de9aa99990","http://resolver.tudelft.nl/uuid:40b0381f-684a-4a3a-ac3e-02de9aa99990","Potential of semiconductor nanowires for single photon sources","Harmand, J.C.; Liu, L.; Patriarche, G.; Tchernycheva, M.; Akopian, N.; Perinetti, U.; Zwiller, V.","","2009","The catalyst-assisted growth of semiconductor nanowires heterostructures offers a very flexible way to design and fabricate single photon emitters. The nanowires can be positioned by organizing the catalyst prior to growth. Single quantum dots can be formed in the core of single nanowires which can then be easily isolated and addressed to generate single photons. Diameter and height of the dots can be controlled and their emission wavelength can be tuned at the optical telecommunication wavelengths by the material composition. The final morphology of a wire can be shaped by the radial/axial growth ratio, offering the possibility to form single mode optical waveguides with a tapered end for efficient photon collection.","semiconductor nanowires; quantum dots; single photon source; photonic wire","en","conference paper","SPIE","","","","","","","","Applied Sciences","Kavli Institute of Nanoscience","","","",""
"uuid:405660d7-4c8d-4ee5-ab4c-a8d5f864d384","http://resolver.tudelft.nl/uuid:405660d7-4c8d-4ee5-ab4c-a8d5f864d384","Gravity field modeling on the basis of GRACE range-rate combinations: Current results and challenge","Ditmar, P.G.; Liu, X.L.","","2007","","","en","conference paper","Harita Dergisi","","","","","","","","Civil Engineering and Geosciences","Geoscience and Remote Sensing","","","",""
"uuid:c6ab174b-f60e-4323-a255-537f1920c115","http://resolver.tudelft.nl/uuid:c6ab174b-f60e-4323-a255-537f1920c115","An effective strategy for porting C++ applications on cell","Varbanescu, A.L.; Sips, H.; Ross, K.A.; Liu, Q.; Liu, L.K.; Natsev, A.; Smith, J.R.","","2007","In this paper we present a solution for efficient porting of sequential C++ applications on the Cell B.E. processor. We present our step-by-step approach, focusing on its generality, we provide a set of code templates and optimization guidelines to support the porting, and we include a set of equations to estimate the performance gain of the new application. As a case-study, we show the use of our solution on a multimedia content analysis application, named MARVEL. The results of our experiments with MARVEL prove the significant performance increase in favor of the application running on Cell when compared with the reference implementation.","cell BE processor; multi-core; MPSoC; parallelization; porting technique; C++ applications","en","conference paper","IEEE","","","","","","","","Electrical Engineering, Mathematics and Computer Science","","","","",""