"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:e8f28f08-e648-4a08-814e-f511359020a4","http://resolver.tudelft.nl/uuid:e8f28f08-e648-4a08-814e-f511359020a4","Prediction of Non-Routine Tasks Workload for Aircraft Maintenance with Supervised Learning","Li, H. (Student TU Delft); Ribeiro, M.J. (TU Delft Air Transport & Operations); Santos, Bruno F. (TU Delft Air Transport & Operations); Tseremoglou, I. (TU Delft Air Transport & Operations)","","2024","Aircraft maintenance scheduling is a focus point for airlines. Maintenance is essential to ensure the airworthiness of aircraft, but it comes at the cost of rendering them unavailable for operations. In current operations, aircraft maintenance scheduling must often be updated to include time for non-routine and non-schedule tasks. These non-routine tasks can increase costs, maintenance workload, and uncertainty of the airlines’ operations. This research introduces a supervised learning framework designed to forecast future non-routine task workloads accurately, improving the accuracy of the planned maintenance schedule. This framework consists of two random forest predictors which estimate the amount of non-routine tasks and the number of future work hours that should be allocated in advance for potential non-routine tasks. Our approach produces highly reliable predictions by leveraging a robust dataset obtained from an international airline. The results show an average of 20% improvement versus an existing on-site sampling method. Furthermore, our in-depth analysis of prediction distributions enables the identification of the underlying causes of significant prediction errors, shedding light on the unpredictabilities inherent to non-routine tasks.","","en","conference paper","American Institute of Aeronautics and Astronautics Inc. (AIAA)","","","","","","","","","","Air Transport & Operations","","",""
"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:7df8dacb-3cff-474c-b1bc-cfed9f6ef3bb","http://resolver.tudelft.nl/uuid:7df8dacb-3cff-474c-b1bc-cfed9f6ef3bb","Contrast-Agnostic Groupwise Registration by Robust PCA for Quantitative Cardiac MRI","Li, Xinqi (Student TU Delft); Zhang, Y. (TU Delft ImPhys/Tao group); Zhao, Y. (TU Delft ImPhys/Tao group); van Gemert, J.C. (TU Delft Pattern Recognition and Bioinformatics); Tao, Q. (TU Delft ImPhys/Tao group)","Camara, Oscar (editor); Puyol-Antón, Esther (editor); Suinesiaputra, Avan (editor); Young, Alistair (editor); Sermesant, Maxime (editor); Tao, Qian (editor); Wang, Chengyan (editor)","2024","Quantitative cardiac magnetic resonance imaging (MRI) is an increasingly important diagnostic tool for cardiovascular diseases. Yet, co-registration of all baseline images within the quantitative MRI sequence is essential for the accuracy and precision of quantitative maps. However, co-registering all baseline images from a quantitative cardiac MRI sequence remains a nontrivial task because of the simultaneous changes in intensity and contrast, in combination with cardiac and respiratory motion. To address the challenge, we propose a novel motion correction framework based on robust principle component analysis (rPCA) that decomposes quantitative cardiac MRI into low-rank and sparse components, and we integrate the groupwise CNN-based registration backbone within the rPCA framework. The low-rank component of rPCA corresponds to the quantitative mapping (i.e. limited degree of freedom in variation), while the sparse component corresponds to the residual motion, making it easier to formulate and solve the groupwise registration problem. We evaluated our proposed method on cardiac T1 mapping by the modified Look-Locker inversion recovery (MOLLI) sequence, both before and after the Gadolinium contrast agent administration. Our experiments showed that our method effectively improved registration performance over baseline methods without introducing rPCA, and reduced quantitative mapping error in both in-domain (pre-contrast MOLLI) and out-of-domain (post-contrast MOLLI) inference. The proposed rPCA framework is generic and can be integrated with other registration backbones.","Groupwise registration; motion correction; Quantitative MRI; Robust PCA","en","conference paper","Springer","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-08-02","","","ImPhys/Tao group","","",""
"uuid:3c4e3e23-f4bc-44fe-b737-ce1e0fcdfed0","http://resolver.tudelft.nl/uuid:3c4e3e23-f4bc-44fe-b737-ce1e0fcdfed0","Towards Cross-Modal Point Cloud Retrieval for Indoor Scenes","Yu, Fuyang (Beihang University); Wang, Zhen (Tokyo Institute of Technology); Li, Dongyuan (Tokyo Institute of Technology); Zhu, P. (TU Delft Web Information Systems); Liang, Xiaohui (Beihang University); Wang, Xiaochuan (Beijing Technology and Business University); Okumura, Manabu (Tokyo Institute of Technology)","Rudinac, Stevan (editor); Worring, Marcel (editor); Liem, Cynthia (editor); Hanjalic, Alan (editor); Jónsson, Björn Pór (editor); Yamakata, Yoko (editor); Liu, Bei (editor)","2024","Cross-modal retrieval, as an important emerging foundational information retrieval task, benefits from recent advances in multimodal technologies. However, current cross-modal retrieval methods mainly focus on the interaction between textual information and 2D images, lacking research on 3D data, especially point clouds at scene level, despite the increasing role point clouds play in daily life. Therefore, in this paper, we proposed a cross-modal point cloud retrieval benchmark that focuses on using text or images to retrieve point clouds of indoor scenes. Given the high cost of obtaining point cloud compared to text and images, we first designed a pipeline to automatically generate a large number of indoor scenes and their corresponding scene graphs. Based on this pipeline, we collected a balanced dataset called CRISP, which contains 10K point cloud scenes along with their corresponding scene images and descriptions. We then used state-of-the-art models to design baseline methods on CRISP. Our experiments demonstrated that point cloud retrieval accuracy is much lower than cross-modal retrieval of 2D images, especially for textual queries. Furthermore, we proposed ModalBlender, a tri-modal framework which can greatly improve the Text-PointCloud retrieval performance. Through extensive experiments, CRISP proved to be a valuable dataset and worth researching. (Dataset can be downloaded at https://github.com/CRISPdataset/CRISP.)","Cross-modal Retrieval; Indoor Scene; Point Cloud","en","conference paper","Springer","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-07-29","","","Web Information Systems","","",""
"uuid:dfe34bf0-575f-403b-b949-5ce569c8b57e","http://resolver.tudelft.nl/uuid:dfe34bf0-575f-403b-b949-5ce569c8b57e","Trajectory Hiding and Sharing for Supply Chains with Differential Privacy","Li, T. (TU Delft Cyber Security); Xu, L. (TU Delft Cyber Security; TU Delft Ship Hydromechanics and Structures); Erkin, Z. (TU Delft Cyber Security); Lagendijk, R.L. (TU Delft Cyber Security)","Tsudik, Gene (editor); Conti, Mauro (editor); Liang, Kaitai (editor); Smaragdakis, Georgios (editor)","2024","With the fast development of e-commerce, there is a higher demand for timely delivery. Logistic companies want to send receivers a more accurate arrival prediction to improve customer satisfaction and lower customer retention costs. One approach is to share (near) real-time location data with recipients, but this also introduces privacy and security issues such as malicious tracking and theft. In this paper, we propose a privacy-preserving real-time location sharing system including (1) a differential privacy based location publishing method and (2) location sharing protocols for both centralized and decentralized platforms. Different from existing location perturbation solutions which only consider privacy in theory, our location publishing method is based on a real map and different privacy levels for recipients. Our analyses and proofs show that the proposed location publishing method provides better privacy protection than existing works under real maps against possible attacks. We also provide a detailed analysis of the choice of the privacy parameter and their impact on the suggested noisy location outputs. The experimental results demonstrate that our proposed method is feasible for both centralized and decentralized systems and can provide more precise arrival prediction than using time slots in current delivery systems.","Applied cryptography; Blockchain; Differential privacy; Location privacy; Privacy-preserving","en","conference paper","Springer","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-08-05","","","Cyber Security","","",""
"uuid:9986a064-4548-49c9-84e3-794c73888ea5","http://resolver.tudelft.nl/uuid:9986a064-4548-49c9-84e3-794c73888ea5","Twin-Delayed Deep Deterministic Policy Gradient for altitude control of a flying-wing aircraft with an uncertain aerodynamic model","Völker, W.J.E. (Student TU Delft); Li, Y. (TU Delft Control & Simulation); van Kampen, E. (TU Delft Control & Simulation)","","2023","Recent research on the Flying V - a flying-wing long-range passenger aircraft - shows that its airframe design is 25% more aerodynamically efficient than a conventional tube-and-wing airframe. The Flying V is therefore a promising contribution towards reduction in climate impact of long-haul flights. However, some design aspects of the Flying V still remain to be investigated, one of which is automatic flight control. Due to the unconventional airframe shape of the Flying V, aerodynamic modelling cannot rely on validated aerodynamic-modelling tools and the accuracy of the aerodynamic model is uncertain. Therefore, this contribution investigates how an automatic flight controller that is robust to aerodynamic-model uncertainty can be developed, by utilising Twin-Delayed Deep Deterministic Policy Gradient (TD3) - a recent deep-reinforcement-learning algorithm. The results show that an offline-trained single-loop altitude controller that is fully based on TD3 can track a given altitude-reference signal and is robust to aerodynamic-model uncertainty of more than 25%.","","en","conference paper","","","","","","","","","","","Control & Simulation","","",""
"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:b10a86f6-14f1-4117-9a3e-4828cc06d855","http://resolver.tudelft.nl/uuid:b10a86f6-14f1-4117-9a3e-4828cc06d855","Human- or Machine-like Music Assistive Robots Effects on Fluency and Memory Recall","Li, Y. (TU Delft Interactive Intelligence); Broz, F. (TU Delft Interactive Intelligence); Neerincx, M.A. (TU Delft Interactive Intelligence)","","2023","Assistive robots are expected to contribute to the solution of major societal problems in healthcare, such as the increasing number of elderly who need informal and professional care over a long period of time. Most of the research focuses on the development of humanlike robots to facilitate human-robot interaction and strengthen the social, cognitive and affective processes. However, there are some possible downsides of this type of ""robot humanizing"", like raising high expectations and causing incorrect mental models of the robots. Machine-like robots, on the other hand, may help to build more realistic mental models and expectations but might bring about less fluent interactions and less pronounced experiences (i.e., less to remember). To test if a human-like robot indeed brings about better interaction fluency and memory recall, we designed two types of robots for a joint human-robot music listening activity: A human-like and a machine-like robot (Pepper). Thirty students participated in the experiment managed by a Wizard-of-Oz set-up. As expected, the human-like robot proved to perform better in terms of fluency and memory recall. Currently, we are preparing a follow-up experiment, consisting of longer sessions with the elderly to see whether this effect persists for this age group and how far the human- or machine-likeness influences the elderly's understanding and expectations of the robot's capabilities.","Fluency; Human-like robot; Machine-like robot; Memory recall; Music; Robot","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Interactive Intelligence","","",""
"uuid:ebf03802-4508-4d52-97f5-9cd586dab35d","http://resolver.tudelft.nl/uuid:ebf03802-4508-4d52-97f5-9cd586dab35d","Adaptive Optimal Flight Control for a Fixed-wing Unmanned Aerial Vehicle using Incremental Value Iteration","Li, Y. (TU Delft Control & Simulation); van Kampen, E. (TU Delft Control & Simulation)","","2023","This paper deals with the design of an adaptive optimal controller for a fixed-wing Unmanned Aerial Vehicle(UAV) using an incremental value iteration algorithm. The incremental model is firstly introduced to linearize a nonlinear system. The recursive least squares(RLS) identification algorithm is then used to identify the incremental model. Based on incremental control, the incremental value iteration algorithm is developed for a nonlinear optimal control problem. Moreover, this algorithm is applied to longitudinal attitude tracking of a fixed-wing unmanned aerial vehicle. Simulation results show that the designed adaptive flight controller is robust to variations in initial value of the angle of attack.","","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.","","2023-10-23","","","Control & Simulation","","",""
"uuid:021b6617-c9bd-4b61-9a93-18f43294fe2e","http://resolver.tudelft.nl/uuid:021b6617-c9bd-4b61-9a93-18f43294fe2e","Federated Learning for Online Resource Allocation in Mobile Edge Computing: A Deep Reinforcement Learning Approach","Zheng, Jingjing (CISTER Research Centre); Li, Kai (CISTER Research Centre); Mhaisen, N. (TU Delft Networked Systems); Ni, Wei (CSIRO: Commonwealth Scientific and Industrial Research); Tovar, Eduardo (CISTER Research Centre); Guizani, Mohsen (Mohamed Bin Zayed University of Artificial Intelligence)","","2023","Federated learning (FL) is increasingly considered to circumvent the disclosure of private data in mobile edge computing (MEC) systems. Training with large data can enhance FL learning accuracy, which is associated with non-negligible energy use. Scheduled edge devices with small data save energy but decrease FL learning accuracy due to a reduction in energy consumption. A trade-off between the energy consumption of edge devices and the learning accuracy of FL is formulated in this proposed work. The FL-enabled twin-delayed deep deterministic policy gradient (FL-TD3) framework is proposed as a solution to the formulated problem because its state and action spaces are large in a continuous domain. This framework provides the maximum accuracy ratio of FL divided by the device’s energy consumption. A comparison of the numerical results with the state-of-the-art demonstrates that the ratio has been improved significantly.","Federated learning; mobile edge computing; online resource allocation; deep 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.","","2023-11-12","","","Networked Systems","","",""
"uuid:e83889c7-ffc0-4d1a-966f-89e87e0cfa0d","http://resolver.tudelft.nl/uuid:e83889c7-ffc0-4d1a-966f-89e87e0cfa0d","EMGSense: A Low-Effort Self-Supervised Domain Adaptation Framework for EMG Sensing","Duan, Di (Shenzhen Research Institute; City University of Hong Kong); Yang, Huanqi (Shenzhen Research Institute; City University of Hong Kong); Lan, G. (TU Delft Embedded Systems); Li, Tianxing (Michigan State University); Jia, Xiaohua (Shenzhen Research Institute; City University of Hong Kong); Xu, Weitao (City University of Hong Kong; Shenzhen Research Institute)","","2023","This paper presents EMGSense, a low-effort self-supervised domain adaptation framework for sensing applications based on Electromyography (EMG). EMGSense addresses one of the fundamental challenges in EMG cross-user sensing—the significant performance degradation caused by time-varying biological heterogeneity—in a low-effort (data-efficient and label-free) manner. To alleviate the burden of data collection and avoid labor-intensive data annotation, we propose two EMG-specific data augmentation methods to simulate the EMG signals generated in various conditions and scope the exploration in label-free scenarios. We model combating biological heterogeneity-caused performance degradation as a multi-source domain adaptation problem that can learn from the diversity among source users to eliminate EMG heterogeneous biological features. To relearn the target-user-specific biological features from the unlabeled data, we integrate advanced self-supervised techniques into a carefully designed deep neural network (DNN) structure. The DNN structure can seamlessly perform two training stages that complement each other to adapt to a new user with satisfactory performance. Comprehensive evaluations on two sizable datasets collected from 13 participants indicate that EMGSense achieves an average accuracy of 91.9% and 81.2% in gesture recognition and activity recognition, respectively. EMGSense outperforms the state-of-the-art EMG-oriented domain adaptation approaches by 12.5%-17.4% and achieves a comparable performance with the one trained in a supervised learning manner.","EMG sensing; biological heterogeneity; domain adaptation; self-supervised 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.","","2023-10-18","","","Embedded Systems","","",""
"uuid:284b17af-71ee-4e79-b75e-0cc3b9ce6079","http://resolver.tudelft.nl/uuid:284b17af-71ee-4e79-b75e-0cc3b9ce6079","Optimizing ML Inference Queries Under Constraints","Li, Z. (TU Delft Web Information Systems); Sun, W. (TU Delft Web Information Systems); Hai, R. (TU Delft Web Information Systems); Bozzon, A. (TU Delft Human-Centred Artificial Intelligence); Katsifodimos, A (TU Delft Web Information Systems)","","2023","The proliferation of pre-trained ML models in public Web-based model zoos facilitates the engineering of ML pipelines to address complex inference queries over datasets and streams of unstructured content. Constructing optimal plan for a query is hard, especially when constraints (e.g. accuracy or execution time) must be taken into consideration, and the complexity of the inference query increases. To address this issue, we propose a method for optimizing ML inference queries that selects the most suitable ML models to use, as well as the order in which those models are executed. We formally define the constraint-based ML inference query optimization problem, formulate it as a Mixed Integer Programming (MIP) problem, and develop an optimizer that maximizes accuracy given constraints. This optimizer is capable of navigating a large search space to identify optimal query plans on various model zoos.","","en","conference paper","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-12-25","","","Web Information Systems","","",""
"uuid:0449bade-c218-438f-85bd-e68fc9c088c1","http://resolver.tudelft.nl/uuid:0449bade-c218-438f-85bd-e68fc9c088c1","Mitigating Mainstream Bias in Recommendation via Cost-sensitive Learning","Li, Roger Zhe (TU Delft Multimedia Computing); Urbano, Julián (TU Delft Multimedia Computing); Hanjalic, A. (TU Delft Intelligent Systems)","","2023","Mainstream bias, where some users receive poor recommendations because their preferences are uncommon or simply because they are less active, is an important aspect to consider regarding fairness in recommender systems. Existing methods to mitigate mainstream bias do not explicitly model the importance of these non-mainstream users or, when they do, it is in a way that is not necessarily compatible with the data and recommendation model at hand. In contrast, we use the recommendation utility as a more generic and implicit proxy to quantify mainstreamness, and propose a simple user-weighting approach to incorporate it into the training process while taking the cost of potential recommendation errors into account. We provide extensive experimental results showing that quantifying mainstreamness via utility is better able at identifying non-mainstream users, and that they are indeed better served when training the model in a cost-sensitive way. This is achieved with negligible or no loss in overall recommendation accuracy, meaning that the models learn a better balance across users. In addition, we show that research of this kind, which evaluates recommendation quality at the individual user level, may not be reliable if not using enough interactions when assessing model performance.","bias mitigation; mainstream bias; recommender systems","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","Intelligent Systems","Multimedia Computing","","",""
"uuid:69264137-4587-47a9-a557-942dd88effe3","http://resolver.tudelft.nl/uuid:69264137-4587-47a9-a557-942dd88effe3","Macaroni: Crawling and Enriching Metadata from Public Model Zoos","Li, Z. (TU Delft Web Information Systems); Hai, R. (TU Delft Web Information Systems); Katsifodimos, A (TU Delft Web Information Systems); Bozzon, A. (TU Delft Human-Centred Artificial Intelligence)","","2023","Machine learning (ML) researchers and practitioners are building repositories of pre-trained models, called model zoos. These model zoos contain metadata that detail various properties of the ML models and datasets, which are useful for reporting, auditing, reproducibility, and interpretability. Unfortunately, the existing metadata representations come with limited expressivity and lack of standardization. Meanwhile, an interoperable method to store and query model zoo metadata is missing. These two gaps hinder model search, reuse, comparison, and composition. In this demo paper, we advocate for standardized ML model metadata representation, proposing Macaroni, a metadata search engine with toolkits that support practitioners to obtain and enrich that metadata.","","en","conference paper","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-12-25","","","Web Information Systems","","",""
"uuid:d6df535b-90e2-48c4-babc-3700bfd9a66b","http://resolver.tudelft.nl/uuid:d6df535b-90e2-48c4-babc-3700bfd9a66b","Maximizing the Potential of Custom RISC-V Vector Extensions for Speeding up SHA-3 Hash Functions","Li, H. (TU Delft Cyber Security); Mentens, Nele (Katholieke Universiteit Leuven; Universiteit Leiden); Picek, S. (TU Delft Cyber Security; Radboud Universiteit Nijmegen)","","2023","SHA-3 is considered to be one of the most secure standardized hash functions. It relies on the Keccak-f[1 600] permutation, which operates on an internal state of 1 600 bits, mostly represented as a 5 x 5 x 64-bit matrix. While existing implementations process the state sequentially in chunks of typically 32 or 64 bits, the Keccak-f[1 600] permutation can benefit a lot from speedup through parallelization. This paper is the first to explore the full potential of parallelization of Keccak-f[1 600] in RISC-V based processors through custom vector extensions on 32-bit and 64-bit architectures. We analyze the Keccak $\mathbf{f}[1 \ 600]$ permutation, composed of five different step mappings, and propose ten custom vector instructions to speed up the computation. We realize these extensions in a SIMD processor described in System Verilog. We compare the performance of our designs to existing architectures based on vectorized application-specific instruction set processors (ASIP). We show that our designs outperform all related work in throughput due to our carefully selected custom vector instructions.","Keccak; SHA-3; Vector Extensions; SIMD Processor; RISC-V","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.","","2023-12-02","","","Cyber Security","","",""
"uuid:232c81d5-78fb-48bb-b7db-82cdc3473d2a","http://resolver.tudelft.nl/uuid:232c81d5-78fb-48bb-b7db-82cdc3473d2a","Mechanistic Investigation of Vertical Sweep Efficiency in Miscible CO2-Water- Coinjection for EOR and CCUS","Yu, G. (United Arab Emirates University); Tang, J. (United Arab Emirates University); Li, L. (University of Chinese Academy of Sciences); Rossen, W.R. (TU Delft Atmospheric Remote Sensing)","","2023","The main objective of this study is to understand the vertical sweep efficiency with miscible CO2-water-coinjection as a secondary recovery method, from multiple perspectives: phase behavior, total relative mobility, fluid densities/viscosities, the driving forces and consequent phase distributions etc. We also seek to provide insights into modeling approaches for representing the injection process by comparing compositional simulation results to those of the fractional-flow method and the model of Stone and Jenkins ( Stone, 1982 ; Jenkins, 1984 ).
We combine compositional simulation and analytical models to interpret the dynamics that affect vertical sweep efficiency in miscible CO2-water-coinjection. Stone’s model for gravity segregation at steady state predicts three phase-distribution zones: mixed zone, override zone and underride zone. In addition to these three zones, we identify from simulations an extended mixed zone and extended override zone in miscible CO2-water-coinjection, contributing to additional oil recovery and CO2 trapping. The extended zones are a result of dispersion that reflects physical and numerical dispersion in the gas-oil displacement front. To the extent that it reflects numerical dispersion, the extended zones can be considered as a numerical artifact.","","en","conference paper","","","","","","","","","","","Atmospheric Remote Sensing","","",""
"uuid:f51feacb-7cd3-4ec1-95f0-cf73faa982c7","http://resolver.tudelft.nl/uuid:f51feacb-7cd3-4ec1-95f0-cf73faa982c7","Full wavefield migration based on eigen-decomposition propagation operators","Li, A.L. (TU Delft ImPhys/Verschuur group; China University of Geosciences); Verschuur, D.J. (TU Delft Applied Geophysics and Petrophysics; TU Delft ImPhys/Verschuur group); Abolhassani, S. (TU Delft ImPhys/Verschuur group)","","2023","Seismic imaging is crucial for subsurface exploration and monitoring, with a focus on deep and complex structures. Seismic wave migration solves the wave equation, and an accurate propagator is essential. Full Wavefield Modeling (FWMod) was developed based on recursive and iterative up/down wavefield propagation, modeling both primaries and multiples. Embedded within Full Wavefield Migration (FWM) it can be used to image data including multiples, resulting in better illumination in case primary illumination is not sufficient. FWM can be efficient and effective, but conventional one-way wave operators, such as Phase Shift Plus Interpolation Migration, have limitations in strongly inhomogeneous media. Local velocity-based one-way operator based on eigen decomposition was proposed and integrated within FWMod and FWM in this study, improving image amplitudes and fidelity and improving converage speed in the least-squares inversion process.","","en","conference paper","","","","","","","","","","","ImPhys/Verschuur group","","",""
"uuid:b569977a-5a4a-4892-9634-63b834ac8e0d","http://resolver.tudelft.nl/uuid:b569977a-5a4a-4892-9634-63b834ac8e0d","Cultivating Researcher-Sensibility in Novice Designers: Exploring Genre-Specific Heuristics for Game Evaluation in a Design Studio","Li, Xueliang (Southern University of Science and Technology); Xue, H. (TU Delft Design Aesthetics)","Marcus, A. (editor); Rosenzweig, E. (editor); Soares, M.M. (editor)","2023","This paper presents an eight-day design studio that teaches heuristic evaluation of games to third-year bachelor students at the School of Design, Southern University of Science and Technology. Through this course, students gain the first-hand experiences of developing heuristics for games through online survey and using them in idea generation and game evaluation. 13 students (working in groups of two or individually) developed 88 heuristics for 8 game genres by analyzing 349 quotes of game reviews collected from online. The heuristics were further developed into questionnaires and tested with invited 51 game players, followed up by post-interviews. The heuristics were also used as inspirational tools to help the students generate design ideas in an ideation exercise. Results of the students’ work indicate usefulness of the heuristics as evaluative and inspirational tools. In the discussion, we reflected on the challenges encountered by the students over the course and how dealing with these challenges could reveal further directions of teaching research methods in HCI studios.","Design Education; Studio; Design Research Methodology; Design Evaluation","en","conference paper","Springer Nature","","","","","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.","","2024-01-09","","","Design Aesthetics","","",""
"uuid:f010bcb0-a98d-485c-b891-4137c4fa0b63","http://resolver.tudelft.nl/uuid:f010bcb0-a98d-485c-b891-4137c4fa0b63","Optimizing Machine Learning Inference Queries for Multiple Objectives","Li, Z. (TU Delft Web Information Systems); Schonfeld, Mariette (Student TU Delft); Hai, R. (TU Delft Web Information Systems); Bozzon, A. (TU Delft Human-Centred Artificial Intelligence); Katsifodimos, A (TU Delft Web Information Systems)","","2023","Given a set of pre-trained Machine Learning (ML) models, can we solve complex analytic tasks that make use of those models by formulating ML inference queries? Can we mitigate different tradeoffs, e.g., high accuracy, low execution costs and memory footprint, when optimizing the queries? In this work we present different multi-objective ML inference query optimization strategies, and compare them on their usability, applicability, and complexity. We formulate Mixed-Integer-Programming-based (MIP) optimizers for ML inference queries that makes use of different objectives to find Pareto-optimal inference query plans.","","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-12-14","","","Web Information Systems","","",""
"uuid:489c66f3-dc1e-4140-89c3-cbe28a5fa04c","http://resolver.tudelft.nl/uuid:489c66f3-dc1e-4140-89c3-cbe28a5fa04c","A Multivariate Poisson Model with Exible Dependence Structure","Li, S. (TU Delft Statistics)","Brito, Mario P. (editor); Aven, Terje (editor); Baraldi, Piero (editor); Cepin, Marko (editor); Zio, Enrico (editor)","2023","Multivariate distributions are indispensable tools for modeling complex data structures with multiple dependent variables. Despite extensive research on discrete multivariate distributions, the multivariate Poisson distribution remains inadequately defined. However, multivariate Poisson counts are not rare and have gained considerable attention in scientific fields such as reliability engineering. Accurately specifying the dependence structure presents a significant challenge in analyzing such data. Although several methods have been proposed in the literature to address this issue, they have limitations in satisfying all feasible correlations. Currently, there is an outstanding question regarding the development of a multivariate Poisson model that is easily interpretable and effectively handles dependent Poisson counts.
In this study, we present a novel multivariate Poisson model that leverages multivariate reduction techniques (MRT) to enable greater flexibility in the dependence structure, particularly for negative correlations, than classical constructions. Our proposed model generalizes existing MRT-based methods by having the same parameters when some of our model's parameters are preset. We demonstrate the feasible regions of correlations and show that our model overcomes the limitations of previous methods, making it ideal for analyzing multivariate Poisson counts. Furthermore, we establish several probabilistic properties, including the probability mass function, the probability-generating function, and the Pearson correlation coefficient. We also provide a detailed discussion of maximum likelihood estimation and an algorithm for generating multivariate Poisson random variables. Our model's superiority is demonstrated through simulations and a real-world example.","","en","conference paper","Research Publishing","","","","","","","","","","Statistics","","",""
"uuid:b3b543ba-9d37-47f3-ba74-f4010ddbf481","http://resolver.tudelft.nl/uuid:b3b543ba-9d37-47f3-ba74-f4010ddbf481","FLAIRS: FPGA-Accelerated Inference-Resistant & Secure Federated Learning","Li, H. (TU Delft Cyber Security); Rieger, Phillip (Technische Universität Darmstadt); Zeitouni, Shaza (Technische Universität Darmstadt); Picek, S. (TU Delft Cyber Security; Radboud Universiteit Nijmegen); Sadeghi, Ahmad Reza (Technische Universität Darmstadt)","O’Conner, L. (editor)","2023","Federated Learning (FL) has become very popular since it enables clients to train a joint model collaboratively without sharing their private data. However, FL has been shown to be susceptible to backdoor and inference attacks. While in the former, the adversary injects manipulated updates into the aggregation process; the latter leverages clients' local models to deduce their private data. Contemporary solutions to address the security concerns of FL are either impractical for real-world deployment due to high-performance overheads or are tailored towards addressing specific threats, for instance, privacy-preserving aggregation or backdoor defenses. Given these limitations, our research delves into the advantages of harnessing the FPGA-based computing paradigm to overcome performance bottlenecks of software-only solutions while mitigating backdoor and inference attacks. We utilize FPGA-based enclaves to address inference attacks during the aggregation process of FL. We adopt an advanced backdoor-aware aggregation algorithm on the FPGA to counter backdoor attacks. We implemented and evaluated our method on Xilinx VMK-180, yielding a significant speed-up of around 300 times on the IoT-Traffic dataset and more than 506 times on the CIFAR-10 dataset.","FPGA Acceleration; Federated Learning (FL); FPGA-based FL; Backdoor-aware FL; Privacy-preserving FL","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-05-02","","","Cyber Security","","",""
"uuid:e2cf8937-a16f-465e-8cdf-4387cb2989ad","http://resolver.tudelft.nl/uuid:e2cf8937-a16f-465e-8cdf-4387cb2989ad","Three-Phase Medium-Voltage Medium-Frequency Transformer for SST in Green Hydrogen Production","Mirzadarani, R. (TU Delft High Voltage Technology Group); Ghaffarian Niasar, M. (TU Delft High Voltage Technology Group); Li, Z. (TU Delft DC systems, Energy conversion & Storage); Qin, Z. (TU Delft DC systems, Energy conversion & Storage); Vaessen, P.T.M. (TU Delft High Voltage Technology Group); Bauer, P. (TU Delft DC systems, Energy conversion & Storage); Van Lieshout, Lou (VONK)","","2023","Green hydrogen production uses renewable energies to energise the electrolysers for hydrogen production. The present paper compares possible solutions and configurations of a medium-frequency transformer (MFT) as part of a solid-state transformer (SST) in green hydrogen production applications. The single-phase and three-phase MFTs are compared and it is shown that a Yd three-phase MFT is the optimum choice for applications that require high power delivery and step-down of the voltage. A summary of previous works about MFT is also provided. Three-phase SST based on modular multilevel converters (MMC) is then described and various cases are investigated to obtain the optimum operational frequency. A 25 MVA, 400 Hz, 25.4 kV / 560V oil-immersed MFT design is presented and is shown that the proposed 400 Hz transformer saves 69% of the active parts' weight compared to a conventional line-frequency transformer (LFT).","electrolyzer; solid-state transformer; mediumfrequency transformer","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-05-16","","","High Voltage Technology Group","","",""
"uuid:b8ee7373-a840-4bfa-b59e-b2274c3bd20f","http://resolver.tudelft.nl/uuid:b8ee7373-a840-4bfa-b59e-b2274c3bd20f","Fuzzy Logic-Based Online Energy Management System for Residential Microgrids","Wu, Jingxuan (Aalborg University); Li, Shuting (Aalborg University); Gui, Yonghao (Oak Ridge National Laboratory); Cvetkovic, M. (TU Delft Intelligent Electrical Power Grids); Vasquez, Juan C. (Aalborg University); Guerrero, Josep M. (Aalborg University)","","2023","A fuzzy logic based online energy management system (FLEMS) is designed in this paper to achieve the optimal electricity cost in a residential Microgrid (MG). The proposed FLEMS is combined by a local energy price model (LEPM) and a fuzzy-logic strategy. The LEPM will preprocess the sampling data to estimate the electricity market and local MG status. The fuzzy-logic mimics the artificial intelligent assessment to economic issues and make decision for the charging and discharging operation for energy storage system (ESS). In the FLEMS, not only electricity price and supply-demand balance, but also ESS state of charge are considered for the efficient and stable operations. The proposed method does not relay on the accurate prediction of renewable energy source and local loads. Historical experience of the system is involved by the LEPM and guides the ESS operation in the fuzzy-logic. A real-world data based household-level residential MG model is established to validate the performance of the FLEMS. A hourly-resolution-Particle swarm optimization (PSO) with perfect day-ahead prediction is implemented as the baseline to verify the superiority of the proposed method.","EMS; energy storage; electricity cost; fuzzy logic; microgrid","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-05-16","","","Intelligent Electrical Power Grids","","",""
"uuid:03dd1891-0d72-4e6b-9d6b-6f0dc87491ca","http://resolver.tudelft.nl/uuid:03dd1891-0d72-4e6b-9d6b-6f0dc87491ca","Improved Wordpcfg for Passwords with Maximum Probability Segmentation","Li, Wenting (Peking University); Yang, Jiahong (Peking University); Cheng, Haibo (Peking University); Wang, Ping (Peking University); Liang, K. (TU Delft Cyber Security)","","2023","Modeling password distributions is a fundamental problem in password security, benefiting the research and applications on password guessing, password strength meters, honey password vaults, etc. As one of the best segment-based password models, WordPCFG has been proposed to capture individual semantic segments (called words) in passwords. However, we find WordPCFG does not address well the ambiguity of password segmentation by maximum matching, leading to the unreasonable segmentation of many password and further the inaccuracy of modeling password distributions. To address the ambiguity, we improve WordPCFG by maximum probability segmentation with A*-like pruning algorithm. The experimental results show that the improved WordPCFG cracks 99.26%–99.95% passwords, with nearly 5.67%–18.01% improvement.","Password; Probabilistic context-free grammar; maximum probability segmentation","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","","","Cyber Security","","",""
"uuid:3fc9087b-c18a-4628-8e5d-723bb6442040","http://resolver.tudelft.nl/uuid:3fc9087b-c18a-4628-8e5d-723bb6442040","GazeNeRF: 3D-Aware Gaze Redirection with Neural Radiance Fields","Ruzzi, Alessandro (ETH Zürich); Shi, X. (TU Delft Pattern Recognition and Bioinformatics); Wang, Xi (ETH Zürich); Li, Gengyan (ETH Zürich); De Mello, Shalini (Nvidia); Chang, Hyung Jin (University of Birmingham); Zhang, X. (TU Delft Pattern Recognition and Bioinformatics); Hilliges, Otmar (ETH Zürich)","O'Conner, Lisa (editor)","2023","We propose GazeNeRF, a 3D-aware method for the task of gaze redirection. Existing gaze redirection methods operate on 2D images and struggle to generate 3D consistent results. Instead, we build on the intuition that the face region and eyeballs are separate 3D structures that move in a coordinated yet independent fashion. Our method leverages recent advancements in conditional image-based neural radiance fields and proposes a two-stream architecture that predicts volumetric features for the face and eye regions separately. Rigidly transforming the eye features via a 3D rotation matrix provides fine-grained control over the desired gaze angle. The final, redirected image is then attained via differentiable volume compositing. Our experiments show that this architecture outperforms naively conditioned NeRF baselines as well as previous state-of-the-art 2D gaze redirection methods in terms of redirection accuracy and identity preservation. Code and models will be released for research purposes.","","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.","","2024-02-22","","","Pattern Recognition and Bioinformatics","","",""
"uuid:30dcc85e-34d0-4fac-8d31-b2ebf2abb332","http://resolver.tudelft.nl/uuid:30dcc85e-34d0-4fac-8d31-b2ebf2abb332","Incremental Generalized Policy Iteration for Adaptive Attitude Tracking Control of a Spacecraft","Li, Y. (TU Delft Control & Simulation); van Kampen, E. (TU Delft Control & Simulation)","","2023","This paper proposes a novel dynamic programming algorithm for nonlinear system optimal control problem, namely Incremental Generalized Policy Iteration (IGPI). The proposed IGPI algorithm combines the advantages of Incremental Control(IC) and Generalized Policy Iteration(GPI). Incremental control can handle the nonlinearity and uncertainty in nonlinear systems without knowing the nonlinear system information, GPI can learn an optimal control law for dynamical systems. Based on the proposed IGPI algorithm, a data-driven adaptive attitude controller is designed for a spacecraft with sloshing liquid fuel. Simulation results demonstrate the effectiveness of the spacecraft attitude controller.","","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.","","2024-01-01","","","Control & Simulation","","",""
"uuid:5ec319af-7e99-41e4-89e8-ea411c51da75","http://resolver.tudelft.nl/uuid:5ec319af-7e99-41e4-89e8-ea411c51da75","Noise PSD Insensitive RTF Estimation in a Reverberant and Noisy Environment","Li, C. (TU Delft Signal Processing Systems); Hendriks, R.C. (TU Delft Signal Processing Systems)","","2023","Spatial filtering techniques typically rely on estimates of the target relative transfer function (RTF). However, the target speech signal is typically corrupted by late reverberation and ambient noise, which complicates RTF estimation. Existing methods subtract the noise covariance matrix to obtain the target plus late reverberation covariance matrix, from where the RTF is estimated. However, the noise covariance matrix is typically unknown. More specifically, the noise power spectral density (PSD) is typically unknown, while the spatial coherence matrix can be assumed known as it might remain time-invariant for a longer time. Using the spatial coherence matrices we simplify the signal model such that the off-diagonal elements are not affected by the PSDs of the late reverberation and the ambient noise. Then we use these elements to estimate the target covariance matrix, from where the RTF can be obtained. Hence, the resulting estimate of the RTF is insensitive to the noise PSD. Experiments demonstrate the estimation performance of our proposed method.","RTF estimation; spatial filter; Eigenvalue 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.","","2023-11-05","","","Signal Processing Systems","","",""
"uuid:f7416a08-2d68-4c67-bc04-a9cec92a3e71","http://resolver.tudelft.nl/uuid:f7416a08-2d68-4c67-bc04-a9cec92a3e71","A Self Bias-flip Piezoelectric Energy Harvester Array without External Energy Reservoirs achieving 488% Improvement with 4-Ratio Switched-PEH DC-DC Converter","Li, Zhen (Fudan University); Chen, Zhiyuan (Fudan University); Law, Man-Kay (University of Macau); Du, S. (TU Delft Electronic Instrumentation); Cheng, Xu (Fudan University); Zeng, Xiaoyang (Fudan University); Han, Jun (Fudan University)","","2023","With the advent of the lnternet-of-Things (1oT) era, sensor nodes are required in almost all fields to achieve a better interaction between humans and the environment. Piezoelectric energy harvester (PEH), which exhibits an equivalent electrical model of an AC current source /P in parallel with the inherent capacitor CP, is a promising technology to resolve the energy problem of such sensor nodes. Recently, inductor-based rectifiers, capacitor-based rectifiers and hybrid rectifiers have been proposed to improve the energy extraction efficiency of PEH devices [1]–[5]. However, these structures all require the aid of additional capacitors or inductors to achieve bias-flip operation, as illustrated in Fig. 1. These extra passive devices are typically large, which can be a major bottleneck in system-volumeconstrained applications such as MEMS [4]. In response to the above problem, this work proposes a novel 8-phase self bias-flip PEH interface with charge recycling and reusing (SBFRR). By using the C P of 4 PEHs as flipping capacitors, this scheme achieves a high voltage flipping efficiency without using extra energy reservoirs. The 4 C P can also serve as flying capacitors to achieve switched-PEH DC-DC (SPDC) conversion for MPPT, while maintaining a MOPIR of >3.5× with a PEH input voltage (Vp) from 0. 78Vto4.9V.","Micromechanical devices; Capacitors; Rectifiers; Voltage; Switches; High-voltage techniques; Reservoirs","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.","","2023-11-11","","","Electronic Instrumentation","","",""
"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: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:e1548744-24b0-4943-aca9-4fc0b930eeb5","http://resolver.tudelft.nl/uuid:e1548744-24b0-4943-aca9-4fc0b930eeb5","Verifiable Credentials with Privacy-Preserving Tamper-Evident Revocation Mechanism","Xu, Li (Student TU Delft); Li, T. (TU Delft Cyber Security); Erkin, Z. (TU Delft Cyber Security)","","2023","Verifiable Credential (VC) is a new standard proposed by the W3C association to facilitate the expression and verification of third-party-verified credentials on the Internet, such as passports or diplomas. However, the current VC data model lacks an explicit revocation design that guarantees the secure operations of the system, which limits its application. In this paper, we specify the requirements for a tamper-evident and privacy-preserving revocation mechanism, based on which we compare existing solutions and propose our revocation mechanism that satisfies all the requirements. Our design combines a cryptographic accumulator and a role-based blockchain. With zero-knowledge proof, the verifier can operate off-chain computation of the revocation status while ensuring the correctness of revocation information published on the blockchain. Our analysis shows that the proposed revocation mechanism can prevent fraud using forged and revoked credentials and relieve privacy concerns caused by the correlation of digital data. Our proof-of-concept implementation demonstrates that our revocation mechanism adds only 42.86 ms overhead in the presentation and 31.36 ms overhead in the verification of verifiable credentials. We also provide scalability analysis, which illustrates that the throughput of our blockchain can meet real-world needs.","verifiable credential; revocation; blockchain; zero-knowledge proof; privacy","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.","","2024-06-11","","","Cyber Security","","",""
"uuid:31083173-787e-4bfd-bcb4-31a3ee69858e","http://resolver.tudelft.nl/uuid:31083173-787e-4bfd-bcb4-31a3ee69858e","2nd Workshop on Multimodal Motion Sickness Detection and Mitigation Methods for Car Journeys - Finding Consensus in the Field","Pöhlmann, Katharina Margareta Theresa (University of Glasgow; KITE-Toronto Rehabilitation Institute); Al Taie, Ammar Jamal Said (University of Glasgow); Li, Gang (University of Glasgow); Dam, Abhraneil (Virginia Tech); Wang, Yu Kai (University of Technology Sydney); Wei, Chun Shu (National Yang Ming Chiao Tung University); Papaioannou, G. (TU Delft Intelligent Vehicles)","","2023","The adoption of automated vehicles will be a positive step towards road safety and environmental benefits. However, one major challenge that still exist is motion sickness. The move from drivers to passengers who will engage in non-driving related tasks as well as the potential change in the layout of the car interior that will come with automated vehicles are expected to result in a worsened experience of motion sickness. The previous workshop [18] highlighted the need for consensus on guidelines regarding study design for motion sickness research. Hence, this workshop will develop a guide for motion sickness research through reflection and discussions on the current methodologies used by experts in the field. Further it will build on the knowledge collected from the previous workshop and will thereby facilitate not only new research ideas and fruitful collaborations but also find a consensus in the field in regard to study design and methodologies.","Automated Vehicles; Comfort; Detection; Mitigation; Motion Sickness","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Intelligent Vehicles","","",""
"uuid:223db2c3-485e-4eff-8a38-d97ab41fc3ff","http://resolver.tudelft.nl/uuid:223db2c3-485e-4eff-8a38-d97ab41fc3ff","Differentiable Transportation Pruning","Li, Yunqiang (Axelera AI); van Gemert, J.C. (TU Delft Pattern Recognition and Bioinformatics); Hoefler, Torsten (ETH Zürich); Moons, Bert (Axelera AI); Eleftheriou, Evangelos (Axelera AI); Verhoef, Bram-Ernst (Axelera AI)","Ceballos, Cristina (editor)","2023","Deep learning algorithms are increasingly employed at the edge. However, edge devices are resource constrained and thus require efficient deployment of deep neural networks. Pruning methods are a key tool for edge deployment as they can improve storage, compute, memory bandwidth, and energy usage. In this paper we propose a novel accurate pruning technique that allows precise control over the output network size. Our method uses an efficient optimal transportation scheme which we make end-to-end differentiable and which automatically tunes the exploration-exploitation behavior of the algorithm to find accurate sparse sub-networks. We show that our method achieves state-of-the-art performance compared to previous pruning methods on 3 different datasets, using 5 different models, across a wide range of pruning ratios, and with two types of sparsity budgets and pruning granularities.","","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:442b79ff-b77a-44d9-bd92-482dab783d8b","http://resolver.tudelft.nl/uuid:442b79ff-b77a-44d9-bd92-482dab783d8b","Enhancing Explainability of Automated Vehicles with Culturally-Aware HMIs","Goodge, Thomas (University of Glasgow); Li, Jingyi (Ludwig Maximilians University); Patel, Shiv G. (University of British Columbia); Gravis, Victor (ENAC); Kim, S. (TU Delft Human Information Communication Design)","","2023","In the future, automated vehicles can allow much longer journeys to be undertaken without a driver. This could involve travel across countries with different road systems, traffic rules, and regulations. Disparate cultures also have different expectations of how vehicles should behave. These need to be taken into account when designing HMIs to convey vehicle behaviour and intent. In this work, we presented four scenarios where culturally-sensitive HMIs could benefit both drivers and other road users in a cross-cultural setting. This video will hopefully provoke further discussion and research interest in cross-culture human-vehicle interaction.","autonomous vehicles; cross-cultural;; eHMIs","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.","","2024-03-18","","","Human Information Communication Design","","",""
"uuid:ec7f49c9-0955-46f4-96d8-f740e502d884","http://resolver.tudelft.nl/uuid:ec7f49c9-0955-46f4-96d8-f740e502d884","Residential Demand-Side Flexibility Provision Under a Multi-Level Segmented Tariff","Li, L. (TU Delft Intelligent Electrical Power Grids); Bruninx, K. (TU Delft Energie and Industrie); Tindemans, Simon H. (TU Delft Intelligent Electrical Power Grids)","","2023","This paper proposes a multi-level segmented tariff to encourage consumers to provide demand response using a battery. The aim of the tariff is to (i) properly reflect consumers’ contribution to the distribution grid cost while ensuring cost recovery for the distribution network operator and (ii) to provide consumers with a financial incentive to flatten their load profile and avoid peak demand. An optimization problem is formulated to describe how consumers can provide demand response by managing their batteries. To evaluate the effectiveness of the proposed multi-level segmented tariff, four case studies were conducted. The results indicate that the multi-level segmented tariff is the most effective in reducing coincident peak demand, with a reduction of 22%. Policymakers and regulators are recommended to consider multi-level segmented distribution tariffs, as it provides an incentive to consumers to manage their assets to provide demand response.","Cost recovery; Cost reflectivity; Demand-side flexibility; Distribution network; Multi-level segmented tariff","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.","","2024-07-30","","","Intelligent Electrical Power Grids","","",""
"uuid:e60b7c5e-ce2e-4b52-a3b7-1178b54afe5e","http://resolver.tudelft.nl/uuid:e60b7c5e-ce2e-4b52-a3b7-1178b54afe5e","Analytical and numerical bounds on entanglement delivery waiting times","Brand, Sebastiaan (Universiteit Leiden); Coopmans, T.J. (Universiteit Leiden); Elkouss Coronas, D. (TU Delft Quantum Computer Science; TU Delft QuTech Advanced Research Centre; Okinawa Institute of Science and Technology Graduate University); Li, Boxi (Forschungszentrum Jülich GmbH)","Hemmer, Philip R. (editor); Migdall, Alan L. (editor)","2023","The vision of a global network that enables quantum communications between any point on Earth is known as the quantum internet. One crucial element of this network is the use of quantum repeater chains, which have the potential to overcome transmission losses and implement entanglement or quantum key distribution protocols over extended distances. There are various proposals for quantum repeaters, but they can generally be evaluated based on two main figures of merit: the average time for end-to-end entanglement delivery and the associated average fidelity. However, characterizing these quantities can be difficult due to factors such as feedback loops, decoherence, entanglement generation being a probabilistic process, and the potential failure of subprotocols. In this talk, I will discuss algorithmic and analytical methods for computing these quantities for relevant families of protocols.","Entanglement; Quantum Communication; Quantum Internet; Quantum Networks; Quantum Repeaters; Waiting Time","en","conference paper","SPIE","","","","","","","2023-09-08","","","Quantum Computer Science","","",""
"uuid:59197d24-8211-43da-b74b-37db18ad43d1","http://resolver.tudelft.nl/uuid:59197d24-8211-43da-b74b-37db18ad43d1","ConceptEVA: Concept-Based Interactive Exploration and Customization of Document Summaries","Zhang, Xiaoyu (University of California); Li, Jianping (University of California); Chi, Po Wei (None); Chandrasegaran, R.S.K. (TU Delft Methodologie en Organisatie van Design); Ma, Kwan Liu (University of California)","","2023","With the most advanced natural language processing and artificial intelligence approaches, effective summarization of long and multi-topic documents - such as academic papers - for readers from different domains still remains a challenge. To address this, we introduce ConceptEVA, a mixed-initiative approach to generate, evaluate, and customize summaries for long and multi-topic documents. ConceptEVA incorporates a custom multi-task longformer encoder decoder to summarize longer documents. Interactive visualizations of document concepts as a network reflecting both semantic relatedness and co-occurrence help users focus on concepts of interest. The user can select these concepts and automatically update the summary to emphasize them. We present two iterations of ConceptEVA evaluated through an expert review and a within-subjects study. We find that participants' satisfaction with customized summaries through ConceptEVA is higher than their own manually-generated summary, while incorporating critique into the summaries proved challenging. Based on our findings, we make recommendations for designing summarization systems incorporating mixed-initiative interactions.","Document Summarization; Interactive Visual Analytics; Knowledge Graph; Mixed-Initiative Interfaces","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Methodologie en Organisatie van Design","","",""
"uuid:405d1d52-f7d3-4462-bdff-d157da5f5609","http://resolver.tudelft.nl/uuid:405d1d52-f7d3-4462-bdff-d157da5f5609","Unlocking Energy Flexibility From Thermal Inertia of Buildings: A Robust Optimization Approach","Li, Y. (TU Delft Team Tamas Keviczky); Yorke-Smith, N. (TU Delft Algorithmics); Keviczky, T. (TU Delft Team Tamas Keviczky)","","2023","Towards integrating renewable electricity generation sources into the grid, an important facilitator is the energy flexibility provided by buildings' thermal inertia. Most of the existing research follows a single-step price- or incentive-based scheme for unlocking the flexibility potential of buildings. In contrast, this paper proposes a novel two-step design approach for better harnessing buildings' energy flexibility. In a first step, a robust optimization model is formulated for assessing the energy flexibility of buildings in the presence of uncertain predictions of external conditions, such as ambient temperature, solar irradiation, etc. In a second step, energy flexibility is activated in response to a feasible demand response (DR) request from grid operators without violating indoor temperature constraints, even in the presence of uncertain external conditions. The proposed approach is tested on a high-fidelity Modelica simulator to evaluate its effectiveness. Simulation results show that, compared with price-based demand-side management, the proposed approach achieves greater energy reduction during peak hours.","","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.","","2024-07-19","","","Team Tamas Keviczky","","",""
"uuid:eed57f32-5772-4fe5-bf0a-f2185c70e000","http://resolver.tudelft.nl/uuid:eed57f32-5772-4fe5-bf0a-f2185c70e000","Standardisation landscape for 6G robotic services","Ghassemian, Mona (Huawei Technologies Duesseldorf); Vukobratovic, Dejan (University of Novi Sad); Papadopoulos, Christos (International Hellenic University); An, Xueli (Huawei Technologies Duesseldorf); Chatzimisios, Periklis (International Hellenic University; University of New Mexico); Aijaz, Adnan (Bristol Research & Innovation Laboratory); Li, Peizheng (Bristol Research & Innovation Laboratory); Valenzuela, Andres Meseguer (Instituto Tecnológico de Informática (ITI)); Venkatesha Prasad, Ranga Rao (TU Delft Networked Systems)","","2023","With the increasing usage of robots in numerous vertical industries, the need for standardised solutions has intensified. A number of research and industrial communities and other Standards Developing Organisations (SDOs) have been actively working to identify areas in the robotics and automation sector that are suitable for standardisation. On top of that, each generation of mobile communications brings in new features and a wealth of new standardisation possibilities. While the deployment of 5G New Radio (5G NR) networks is expanding, the race for 6G is already starting to take shape with a number of proposed enabling technologies such as the integrated communication and sensing (ISAC) which can revolutionize the robotic technology. Since the two sectors of robotic and communication technologies advancements have overlapping areas for research and development, the SDOs’ activities need to address the commonalities, to allow a harmonized and unified platform that formally adopts and confirms best practices in 6G and robotics as standards. In this work, we present relevant industry standardisation, associations, and fora for both mobile communication and robotic industries based on the ETSI Classification of SDOs. We present the standardisation landscape for 6G and robotics and highlight the gap in this multidisciplinary standardisation, sharing key recommendations.","6G architecture; 6G standardisation; robotic application requirements; standardisation landscape; tele-robotics","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.","","2024-09-04","","","Networked Systems","","",""
"uuid:fb6b9ce4-9b73-417b-a05c-ac9c91736c5d","http://resolver.tudelft.nl/uuid:fb6b9ce4-9b73-417b-a05c-ac9c91736c5d","Scenario-Game ADMM: A Parallelized Scenario-Based Solver for Stochastic Noncooperative Games","Li, Jingqi (University of California); Chiu, Chih Yuan (University of California); Peters, L. (TU Delft Learning & Autonomous Control); Palafox, Fernando (University of California); Karabag, Mustafa (The University of Texas at Austin); Alonso-Mora, J. (TU Delft Learning & Autonomous Control); Sojoudi, Somayeh (University of California); Tomlin, Claire (University of California); Fridovich-Keil, David (The University of Texas at Austin)","","2023","Decision-making in multi-player games can be extremely challenging, particularly under uncertainty. In this work, we propose a new sample-based approximation to a class of stochastic, general-sum, pure Nash games, where each player has an expected-value objective and a set of chance constraints. This new approximation scheme inherits the accuracy of objective approximation from the established sample average approximation (SAA) method and enjoys a feasibility guarantee derived from the scenario optimization literature. We characterize the sample complexity of this new game-theoretic approximation scheme, and observe that high accuracy usually requires a large number of samples, which results in a large number of sampled constraints. To accommodate this, we decompose the approximated game into a set of smaller games with few constraints for each sampled scenario, and propose a decentralized, consensus-based ADMM algorithm to efficiently compute a generalized Nash equilibrium (GNE) of the approximated game. We prove the convergence of our algorithm to a GNE and empirically demonstrate superior performance relative to a recent baseline algorithm based on ADMM and interior point method.","","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.","","2024-07-19","","","Learning & Autonomous Control","","",""
"uuid:42b3bab2-58e5-47a4-83fe-1a752008ec31","http://resolver.tudelft.nl/uuid:42b3bab2-58e5-47a4-83fe-1a752008ec31","Geometry-Aware Distributed Kalman Filtering for Affine Formation Control under Observation Losses","Li, Z. (TU Delft Signal Processing Systems); Rajan, R.T. (TU Delft Signal Processing Systems)","","2023","Affine formation control of multiagent systems has recently received increasing attention in various applications. The distributed control of these agents, under single integrator dynamics, relies on the observations of relative positions of the neighboring agents, which when unavailable is detrimental to the mission. In this paper, we propose an adaptive fusion estimator of the relative positions under intermittent and consecutive observation loss settings. A relative affine localization (RAL) solution is developed by exploiting the geometry of affine formation, which is then embedded into a distributed relative Kalman filtering (RKF) framework, leading to the geometry-aware relative Kalman filter (GA-RKF). We show through simulations that the GA-RKF exhibits enhanced robustness to both intermittent and consecutive observation losses, as compared to RAL and existing state-of-art methods.","distributed Kalman filter; formation control; multiagent systems; sensor fusion","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.","","2024-02-26","","","Signal Processing Systems","","",""
"uuid:1bf43af1-cdc8-4d26-8449-1aaf77db8a4f","http://resolver.tudelft.nl/uuid:1bf43af1-cdc8-4d26-8449-1aaf77db8a4f","Amalur: Data Integration Meets Machine Learning","Hai, R. (TU Delft Web Information Systems); Koutras, C. (TU Delft Web Information Systems); Ionescu, A. (TU Delft Web Information Systems); Li, Z. (TU Delft Web Information Systems); Sun, W. (TU Delft Web Information Systems); van Schijndel, Jessie (Student TU Delft); Kang, Yan (WeBank); Katsifodimos, A (TU Delft Web Information Systems)","","2023","Machine learning (ML) training data is often scattered across disparate collections of datasets, called data silos. This fragmentation poses a major challenge for data-intensive ML applications: integrating and transforming data residing in different sources demand a lot of manual work and computational resources. With data privacy and security constraints, data often cannot leave the premises of data silos, hence model training should proceed in a decentralized manner. In this work, we present a vision of how to bridge the traditional data integration (DI) techniques with the requirements of modern machine learning. We explore the possibilities of utilizing metadata obtained from data integration processes for improving the effectiveness and efficiency of ML models. Towards this direction, we analyze two common use cases over data silos, feature augmentation and federated learning. Bringing data integration and machine learning together, we highlight new research opportunities from the aspects of systems, representations, factorized learning and federated learning.","","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-01-26","","","Web Information Systems","","",""
"uuid:d076ce95-c521-4007-b4a1-6b40b6019a2d","http://resolver.tudelft.nl/uuid:d076ce95-c521-4007-b4a1-6b40b6019a2d","Nanoindentation characterization of sintered porous Cu nanoparticles used in power electronics packaging – A molecular dynamic simulation study","Hu, D. (TU Delft Electronic Components, Technology and Materials); Li, Z. (TU Delft Electronic Components, Technology and Materials); Fan, J. (TU Delft Electronic Components, Technology and Materials; Shanghai Engineering Technology Research Center; Research Institute of Fudan University, Ningbo); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)","","2023","As a critical part of speeding up industrial electrification, power electronics, and its packaging technology are undergoing rapid development. Cu nanoparticle sintering technology has therefore received extensive attention for its excellent performance in the die-attachment layer, where the mechanical properties are essential to be known for design for reliability. Both sintering and subsequent nanoindentation were studied by simulation. The effect of porosity on the nanoindentation response was investigated by setting different initial packing densities. In addition, the impact of indenter size and indentation positions on the nanoindentation response were discussed. The nanoindentation behaviors were studied by extracting loading-displacement (P-h) curves and calculating elastic modulus and hardness. In addition, the microstructure evolution was adopted using atomic configuration to study the nanoindentation mechanism. This work offers valuable insights into the Cu sinter paste preparation phase for sintering technology.","Nanoindentation; Sintering technology; Cu nanoparticles; molecular dynamics","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.","","2024-09-18","","","Electronic Components, Technology and Materials","","",""
"uuid:266ac5de-2ed6-46ff-b751-267f1fae97d1","http://resolver.tudelft.nl/uuid:266ac5de-2ed6-46ff-b751-267f1fae97d1","Drug Trafficking in Relation to Global Shipping Network","Leibbrandt, Louise (Student TU Delft); Zhang, S. (TU Delft Multimedia Computing); Roelvink, M.A.T. (TU Delft Support Delft Institute of Applied Mathematics); Bergkamp, Stan (Student TU Delft); Li, Xinqi (Student TU Delft); Bisschop, Lieselot (Erasmus Universiteit Rotterdam); Wingerde, Karin van (Erasmus Universiteit Rotterdam); Wang, H. (TU Delft Multimedia Computing)","Cherifi, Hocine (editor); Mantegna, Rosario Nunzio (editor); Rocha, Luis M. (editor); Cherifi, Chantal (editor); Micciche, Salvatore (editor)","2023","This paper aims to understand to what extent the amount of drug (e.g., cocaine) trafficking per country can be explained and predicted using the global shipping network. We propose three distinct network approaches, based on topological centrality metrics, Susceptible-Infected-Susceptible spreading process and a flow optimization model of drug trafficking on the shipping network, respectively. These approaches derive centrality metrics, infection probability, and inflow of drug traffic per country respectively, to estimate the amount of drug trafficking. We use the amount of drug seizure as an approximation of the amount of drug trafficking per country to evaluate our methods. Specifically, we investigate to what extent different methods could predict the ranking of countries in drug seizure (amount). Furthermore, these three approaches are integrated by a linear regression method in which we combine the nodal properties derived by each method to build a comprehensive model for the cocaine seizure data. Our analysis finds that the unweighted eigenvector centrality metric combined with the inflow derived by the flow optimization method best identifies the countries with a large amount of drug seizure (e.g., rank correlation 0.45 with the drug seizure). Extending this regression model with two extra features, the distance of a country from the source of cocaine production and a country’s income group, increases further the prediction quality (e.g., rank correlation 0.79). This final model provides insights into network derived properties and complementary country features that are explanatory for the amount of cocaine seized. The model can also be used to identify countries that have no drug seizure data but are possibly susceptible to cocaine trafficking.","Drug seizure; Drug trafficking; Network method; Shipping network","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.","","2023-07-26","","","Multimedia Computing","","",""
"uuid:1f4e6917-fa22-41c1-b7fb-39ce908312bb","http://resolver.tudelft.nl/uuid:1f4e6917-fa22-41c1-b7fb-39ce908312bb","Mapping XR Platforms: Analyzing Immersion from the Designer’s Perspective","Li, M. (TU Delft Applied Ergonomics and Design; Xi’an Jiaotong University); Houwing, L.D. (TU Delft Teaching & Learning Services); Albayrak, A. (TU Delft Applied Ergonomics and Design); Shidujaman, Mohammad (Independent University); van Eijk, D.J. (TU Delft Applied Ergonomics and Design)","Kurosu, Masaaki (editor); Hashizume, Ayako (editor)","2023","Understanding humans are the key to developing optimal design solutions for product-service systems. In this sense, the experiential approach is in line but might go beyond typical Human Centered Design (HCD) methods in that it focuses on generating positive experiences that contribute directly to human well-being. Extended Reality (XR) showed the potential to replicate or simulate experience as a whole and gained attention from design communities. XR platforms confused design practitioners due to their fast-advancing amounts and relevant experiences. Hence, this study introduced two surveys on XR platforms to clarify which experiences they could provide and when to implement them into HCD processes. Survey 1 categorized XR platforms according to their key attributes and mapped them into the Experience Matrix. Survey 2 invented two designer personas and a fictional project to analyze barriers and strategies to implement XR platforms into design processes. Eighty-eight XR platforms were categorized into nineteen clusters, where creation and simulation had the highest numbers. Regarding implementing XR in design practices, the cost is still the key concern and there's a trade-off between software cost and assets purchased for different types of designers.","Design Tools; Experience Design; Immersion; XR platforms","en","conference paper","Springer","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-01-09","","","Applied Ergonomics and Design","","",""
"uuid:0e6a3cec-c162-4cc6-befe-10cb9c487416","http://resolver.tudelft.nl/uuid:0e6a3cec-c162-4cc6-befe-10cb9c487416","A Simulation Study on Characterizing Transfer Functions of Railway Tracks Using Train-Borne Laser Doppler Vibrometer","Zeng, Y. (TU Delft Railway Engineering); Nunez, Alfredo (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering)","Limongelli, Maria Pina (editor); Giordano, Pier Francesco (editor); Gentile, Carmelo (editor); Quqa, Said (editor); Cigada, Alfredo (editor)","2023","Due to train load and aging, the dynamic properties of railway tracks degrade over time and deviate over space, which should be monitored to facilitate track maintenance decisions. A train-borne laser Doppler vibrometer (LDV) can directly measure track vibrations in response to the moving train load, which can be potentially applied to large-scale rail infrastructure monitoring. This paper characterizes track structures as a distributed system by estimating transfer functions between the wheel-rail force and the response of each sleeper measured by a train-borne LDV. A challenge with this technique is that a train-borne LDV measures only a fragment of the response for each sleeper while the train load is moving. To investigate the feasibility of this technique and the influence of key factors, we perform numerical simulations using a vehicle-track model and analyze the estimation performance through comparison with simulated impact hammer tests. We find that the transfer function estimated under a moving excitation is close to but noisier than that estimated under an impact load. Partial measurement affects the estimation performance significantly, and a wider sleeper provides a better estimate and a higher frequency resolution. Train speed is a crucial factor for a train-borne LDV system. As the vehicle speed increases, the estimation performance gets better at high frequencies but worse at low frequencies.","Laser Doppler Vibrometer; Moving Load; Railway Tracks; Transfer Function Estimation; Vibration Measurement","en","conference paper","Springer","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-02-02","","","Railway Engineering","","",""
"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:1ba883cb-6fe7-456b-bbea-89d57e327be4","http://resolver.tudelft.nl/uuid:1ba883cb-6fe7-456b-bbea-89d57e327be4","Child’s Personality and Self-Disclosures to a Robot Persona “In-The-Wild”","Neerincx, Anouk (Universiteit Utrecht); Li, Y. (TU Delft Interactive Intelligence); van de Sande, Kelvin (Universiteit Utrecht); Broz, F. (TU Delft Interactive Intelligence); Neerincx, M.A. (TU Delft Interactive Intelligence); de Graaf, Maartje (Universiteit Utrecht)","","2023","Social robots can support children in their socio-emotional development [38]. To improve the cooperation between a child and a social robot, a good relationship is vital. Self-disclosure is an essential element for building personal relationships. Yet, knowledge about the effects of self-disclosure in child-robot interactions is still lacking. To investigate effects of robot persona, child personality, and self-disclosure category on self-disclosure in child-robot interaction, we have conducted a field study at a science festival in which children had a conversation with a robot that either behaved human-like or robot-like. The results show a significant difference in the amount of self-disclosure (in conversation duration) between the two robot personas. Additionally, significant relationships were found between conscientiousness and extraversion and amount of self-disclosure (in word count). The participant disclosed significantly more about the category `Attitudes and Opinions’ than about ‘School’. Finally, a thematic analysis shows that the content of the conversations can be categorised in five plus one themes. Between robot personas, the content of the conversations did not differ in terms of conversation themes. However, in both conditions, we found that children generally feel comfortable sharing unpleasant experiences about present themes (such as COVID) in a first encounter with a robot.","","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-05-13","","","Interactive Intelligence","","",""
"uuid:239edf2e-8e04-4e9a-8fb9-c749e9dde5f9","http://resolver.tudelft.nl/uuid:239edf2e-8e04-4e9a-8fb9-c749e9dde5f9","Large Car-following Data Based on Lyft level-5 Open Dataset: Following Autonomous Vehicles vs. Human-driven Vehicles","Li, G. (TU Delft Transport and Planning); Jiao, Y. (TU Delft Transport and Planning); Knoop, V.L. (TU Delft Transport and Planning); Calvert, S.C. (TU Delft Transport and Planning); van Lint, J.W.C. (TU Delft Transport and Planning)","","2023","Car-Following (CF), as a fundamental driving behaviour, has significant influences on the safety and efficiency of traffic flow. Investigating how human drivers react differently when following autonomous vs. human-driven vehicles (HV) is thus critical for mixed traffic flow. Research in this field can be expedited with trajectory datasets collected by Autonomous Vehicles (AVs). However, trajectories collected by AVs are noisy and not readily applicable for studying CF behaviour. This paper extracts and enhances two categories of CF data, HV-following-AV (H-A) and HV-following-HV (H-H), from the open Lyft level-5 dataset. First, CF pairs are selected based on specific rules. Next, the quality of raw data is assessed by anomaly analysis. Then, the raw CF data is corrected and enhanced via motion planning, Kalman filtering, and wavelet denoising. As a result, 29k+ H-A and 42k+ H-H car-following segments are obtained, with a total driving distance of 150k+ km. A diversity assessment shows that the processed data cover complete CF regimes for calibrating CF models. This open and ready-to-use dataset provides the opportunity to investigate the CF behaviours of following AVs vs. HVs from real-world data. It can further facilitate studies on exploring the impact of AVs on mixed urban traffic.","Car-following; trajectory dataset; autonomous vehicle; driving behaviour","en","conference paper","","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-03-28","","","Transport and Planning","","",""
"uuid:df4e36ee-2da6-40da-9ac0-49b476451ff4","http://resolver.tudelft.nl/uuid:df4e36ee-2da6-40da-9ac0-49b476451ff4","Bulk Acoustic Wave Based Mocrfluidic Particle Sorting with Capacitive Micromachined Ultrasonic Transducers","Kawasaki, S. (TU Delft Electronic Components, Technology and Materials); Yeh, Jia-Jun (Student TU Delft); Saccher, M. (TU Delft Electronic Components, Technology and Materials); Li, Jian (Student TU Delft); Dekker, R. (Philips Research)","","2022","The main limitation of acoustic particle separation for microfluidic application is its low sorting efficiency. This is due to the weak coupling of surface acoustic waves (SAWs) into the microchannel. In this work, we demonstrate bulk acoustic wave (BAW) particle sorting using capacitive micromachined ultrasonic transducers (CMUTs) for the first time. A collapsed mode CMUT was driven in air to generate acoustic pressure within the silicon substrate in the in-plane direction of the silicon die. This acoustic pressure was coupled into a water droplet, positioned at the side of the CMUT die, and measured with an optical hydrophone. By using a beam steering approach, the ultrasound generated from 32 CMUT elements were added in-phase to generate a maximum peak-to-peak pressure of 0.9 MPa. Using this pressure, 10 µm latex beads were sorted almost instantaneously.","CMUT; Microfluidic particle sorting; Acoustic particle sorting; bulk acoustic 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.","","2022-08-11","","","Electronic Components, Technology and Materials","","",""
"uuid:f5f92b4f-b141-4f6e-befa-e25ee6c0800d","http://resolver.tudelft.nl/uuid:f5f92b4f-b141-4f6e-befa-e25ee6c0800d","Decentralized Private Freight Declaration & Tracking with Data Validation","Li, T. (TU Delft Cyber Security); Vos, J.V. (TU Delft Cyber Security); Erkin, Z. (TU Delft Cyber Security)","","2022","In January 2017, a truck crossed the border between Spain and France for the first time using an e-CMR: An electronic version of the primary transport document required for inter-European logistics. Since that crossing, researchers and logistic organizations have proposed a large number of ideas to further digitize Europe’s supply chain. Many of these ideas involve blockchains, but not all of them validate the data that is posted to them. As a result, participants can make illegitimate claims: Even though the blockchain enables transparency and immutability of the data stores, it does not ensure veracity. We provide several examples of works about information sharing in the supply chain that do not perform such validation. One work that does use the blockchain’s validation functionality is DEFEND. DEFEND addresses customs agencies’ lack of information for international freight inspection by tracking shipping containers throughout their journey. As containers pass from one operator to another, the blockchain participants ensure that containers are not doubly spent. In this work, we propose an extension of DEFEND, in which we further extend the capabilities for validation. Moreover, we provide actual cryptographic protocols to preserve participants’ privacy while DEFEND only described privacy on a high level. Finally, by making a more fine-grained distinction between different actors in the chain, we model the entire supply chain from buyer to seller. As a result, the buyer and seller can now track the respective package’s whereabouts through each leg of its journey.","supply chain management; blockchain technology; freight declaration","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.","","2022-11-06","","","Cyber Security","","",""
"uuid:b423776c-458c-4c16-8abe-43ef2dbd3241","http://resolver.tudelft.nl/uuid:b423776c-458c-4c16-8abe-43ef2dbd3241","Low Complex Accurate Multi-Source RTF Estimation","Li, C. (TU Delft Signal Processing Systems); Martinez, Jorge (TU Delft Electrical Engineering Education); Hendriks, R.C. (TU Delft Signal Processing Systems)","","2022","Many multi-microphone algorithms depend on knowing the relative acoustic transfer functions (RTFs) of the individual sound sources in the acoustic scene. However, accurate joint RTF estimation for multiple sources is a challenging problem. Existing methods to jointly estimate the RTF for multiple sources have either no satisfying performance, or, suffer from a very large computational complexity. In this paper, we propose a method for robust estimation of the individual RTFs in a multi-source acoustic scenario. The presented algorithm is based on linear algebraic concepts and therefore of lower computational complexity compared to a recently presented state-of-the-art algorithm, while having a similar performance. Experimental results are presented to demonstrate the RTF estimation performance as well as the noise reduction performance when combining the estimated RTFs with a beamformer.","Joint diagonalization; microphone array signal processing; source separation; RTF estimation; speech enhancement","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","","","Signal Processing Systems","","",""
"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:0ad4907a-08dd-47f9-88b6-9da11b458ca3","http://resolver.tudelft.nl/uuid:0ad4907a-08dd-47f9-88b6-9da11b458ca3","Relative Affine Localization for Robust Distributed Formation Control","Li, Z. (Student TU Delft); Rajan, R.T. (TU Delft Signal Processing Systems)","Louveaux, Jérôme (editor); Quitin, François (editor)","2022","Multiagent systems have been widely researched and deployed in the industry for their potential to collectively achieve goals by distributing tasks to individual agents [1]–[4]. Formation control, one of the many applications of multiagent systems, aims at steering agents into a stable geometric pattern in space [3], [4]. There has been a variety of crafted distributed controllers in literature based on different dynamics that agents follow, and different variables that agents sense and control [5]. Affine formation control is brought to the spotlight where N agents in RD converge to the target formation up to an affine transformation [6]. A more general scenario of affine formation control is the dynamic formation maneuvering problem where the target configuration is time-varying and the agents need to not only converge to the desired formation but also track the maneuvering pattern. This problem is addressed in [7] where a series of controller designs are introduced depending on the dynamics of the agents...","tensors; tensor-train; Kalman filter; SVM; seizure; epilepsy; detection","en","conference paper","","","","","","","","","","","Signal Processing Systems","","",""
"uuid:fe24f256-8c0e-4422-b820-9ee42cc708e3","http://resolver.tudelft.nl/uuid:fe24f256-8c0e-4422-b820-9ee42cc708e3","Self-supervised Monocular Multi-robot Relative Localization with Efficient Deep Neural Networks","Li, S. (TU Delft Control & Simulation); de Wagter, C. (TU Delft Control & Simulation); de Croon, G.C.H.E. (TU Delft Control & Simulation)","Pappas, George J. (editor); Kumar, Vijay (editor)","2022","Relative localization is an important ability for multiple robots to perform cooperative tasks in GPS-denied environments. This paper presents a novel autonomous positioning framework for monocular relative localization of multiple tiny flying robots. This approach does not require any groundtruth data from external systems or manual labeling. Instead, the proposed framework is able to label real-world images with 3D relative positions between robots based on another onboard relative estimation technology, using ultra-wideband (UWB). After training in this self-supervised manner, the proposed deep neural network (DNN) can predict relative positions of peer robots by purely using a monocular camera. This deep learning-based visual relative localization is scalable, distributed, and autonomous. We also built an open-source and lightweight simulation pipeline by using Blender for 3D rendering, which allows synthetic image generation of other robots, and generalized training of the neural network. The proposed localization framework is tested on two real-world Crazyflie2 quadrotors by running the DNN on the onboard AIdeck (a tiny AI chip and monocular camera). All results demonstrate the effectiveness of the self-supervised multi-robot localization method. Video: https://youtu.be/7arkaIblPps","","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:2d80cc65-d7ea-4a5f-a2e0-191acd31c708","http://resolver.tudelft.nl/uuid:2d80cc65-d7ea-4a5f-a2e0-191acd31c708","A multiple spiking neural network architecture based on fuzzy intervals for anomaly detection: a case study of rail defects","Phusakulkajorn, W. (TU Delft Railway Engineering); Hendriks, J.M. (TU Delft Railway Engineering); Moraal, J. (TU Delft Railway Engineering); Dollevoet, R.P.B.J. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering); Nunez, Alfredo (TU Delft Railway Engineering)","","2022","In this paper, a fuzzy interval-based method is proposed for solving the problem of rail defect detection relying on an on-board measurement system and a multiple spiking neural network architecture. Instead of outputting binary values (defect or not defect), all data will belong to both classes with different spreads that are given by two fuzzy intervals. The multiple spiking neural networks are used to capture different sources of uncertainties. In this paper, we consider uncertainties in the parameters of spiking neural networks during the training phase. The proposed method comprises two steps. In the first step,
multiple sets of the firing times for both classes are obtained from multiple spiking neural networks. In the second step, the obtained multiple sets of firing times are fuzzy numbers and they are used to construct fuzzy intervals. The proposed method is showcased with the problem of rail defect detection. The
numerical analysis indicates that the fuzzy intervals are suitable to make use of the information provided by the multiple spike neural networks. Finally, with the proposed method, we improve the interpretability of the decision making regarding the detection of anomalies.","spiking neural network; parameter uncertainty; prediction interval; interpretability; anomaly detection","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","","","Railway Engineering","","",""
"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:7f38438e-4c18-45c8-9273-05af89396c61","http://resolver.tudelft.nl/uuid:7f38438e-4c18-45c8-9273-05af89396c61","Fast Assessment of the Impact of Multi-Scale Geological Heterogeneities on Flow Behaviour in Complex Carbonate Reservoirs","Li, Jiahong (Heriot-Watt University); Geiger, S. (TU Delft Applied Geology); Gomes, Jorge Costa (Heriot-Watt University); Petrovskyy, Dmytro (Heriot-Watt University); Jacquemyn, Carl (Imperial College London); Hampson, Gary (Imperial College London); Jackson, Matthew (Imperial College London); Silva, Julio Daniel Machado (University of Calgary); Judice, Sicilia (University of Calgary)","","2022","We discuss the application of the new open-source Rapid Reservoir Modelling software (RRM) to create a suite of 3D reservoir models of a complex carbonate formation where each model is increasingly more refined such that progressively more small-scale geological structures are preserved.
Using flow diagnostics we then calculate key metrics for the dynamic reservoir behaviour to quantify the similarities and dissimilarities of the flow behaviour across the different models. This analysis allows us to identify at which scale geological heterogeneities need to be resolved in the reservoir model to capture the essential flow behaviours.
The workflow presented in this study hence allows us to efficiently and effectively test different geological concepts and analyse how multi-scale geological heterogeneities that may need to be represented in a reservoir model impact the predicted dynamic response, so as to design more reliable and robust reservoir models for a broad range of geoenergy applications.","","en","conference paper","European Association of Geoscientists & Engineers","","","","","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","","","Applied Geology","","",""
"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:41ad58da-b6d8-42bc-bc85-9ba1d86253d9","http://resolver.tudelft.nl/uuid:41ad58da-b6d8-42bc-bc85-9ba1d86253d9","Inactivation of Escherichia coli and Staphylococcus aureus by using a UVC-LED module with a multi-wavelength setting","Lu, Zhiwei (Guilin University of Electronic Technology); Li, Xiaoling (Guilin University of Electronic Technology); Wei, Jinxiu (Guilin University of Electronic Technology); Cai, Miao (Guilin University of Electronic Technology); Yang, Daoguo (Guilin University of Electronic Technology); Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials; Shenzhen Institute of Wide-bandgap Semiconductors)","","2022","UVC-LED is known as a deep ultraviolet LED. The application development and disinfection efficiency of UVC-LED modules are important problems encountered when UVC-LED products are rushed into commercialization. In this article, a specific disinfection experiment with a UVC-LED module was combined to analyze the disinfection efficiency. UVC-LEDs with wavelengths of 260 and 280 nm were used and supplemented with UVA-LEDs with wavelengths of 360 and 390 nm. The module was packaged to investigate the inactivation of Escherichia coli and Staphylococcus aureus. Two new findings were obtained through the analysis and comparison of the experiments. First, the short wavelength from UVA might have an enhanced destructive effect on microorganisms when the radiation intensity of UVA-LED was sufficient with coupling UVA and UVC. Second, 260 nm UVC-LED lamp beads might have a shorter response time to inactivate microorganisms than 280 nm UVC-LED lamp beads. Bactericidal experiments near the surface and different radiation distances showed that the inactivation rate reached 99.9% after 1 min of exposure when the UVC-LED module was set at 260 or 280 nm wavelength lamp beads for disinfection. The disinfection efficiency of 280 nm UVC-LED lamp beads was higher than that of 260 nm UVC-LED lamp beads because of the increased UV intensity. The radiation distance was within 7.5 cm range, the exposure time was 60 s, the inactivation rate was over 99.9%, and the disinfection effect was remarkable. For current UVC-LED applications, such as near-surface UVC-LED, disinfection and air purification products have a high value.","UVC-LED; disinfection experiment; inactivation","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:fce3c05c-fd1d-436c-8404-09291c52b840","http://resolver.tudelft.nl/uuid:fce3c05c-fd1d-436c-8404-09291c52b840","A scalable SIMD RISC-V based processor with customized vector extensions for CRYSTALS-kyber","Li, H. (TU Delft Cyber Security); Mentens, Nele (Universiteit Leiden; Katholieke Universiteit Leuven); Picek, S. (TU Delft Cyber Security; Radboud Universiteit Nijmegen)","","2022","This paper uses RISC-V vector extensions to speed up lattice-based operations in architectures based on HW/SW co-design. We analyze the structure of the number-theoretic transform (NTT), inverse NTT (INTT), and coefficient-wise multiplication (CWM) in CRYSTALS-Kyber, a lattice-based key encapsulation mechanism. We propose 12 vector extensions for CRYSTALS-Kyber multiplication and four for finite field operations in combination with two optimizations of the HW/SW interface. This results in a speed-up of 141.7, 168.7, and 245.5 times for NTT, INTT, and CWM, respectively, compared with the baseline implementation, and a speed-up of over four times compared with the state-of-the-art HW/SW co-design using RV32IMC.","ISA extension; lattice-based cryptography; polynomial operation; RISC-V; SIMD processor; vector instruction","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","","","","","","Cyber Security","","",""
"uuid:1a7478c1-59ea-476d-bbbf-23b5a9a39f98","http://resolver.tudelft.nl/uuid:1a7478c1-59ea-476d-bbbf-23b5a9a39f98","Benni’s Forest: A serious game on the challenges of reforestation","Bolijn, Hidde (Student TU Delft); Li, Martin (Student TU Delft); Reurink, Andries (Student TU Delft); van Rijn, Cas (Student TU Delft); Bidarra, Rafael (TU Delft Computer Graphics and Visualisation)","","2022","Many people think of reforestation projects as one-dimensional, simply consisting of planting trees. In reality, a reforestation project takes into account a wide variety of factors, of which the three most important are improving soil quality, reducing fire hazard, and ensuring the prosperity of the community. We posit that a simplistic view on such projects is detrimental for a more committed and serious societal awareness and support of sustainable reforestation. Therefore, it is desirable that more people have a better understanding of the interplay of these factors, as they will likely become more involved in reforestation projects. We present Benni’s Forest, a serious game aimed at increasing awareness of the challenges of reforestation projects. Benni’s Forest is a simulation game, in which the player is responsible for a reforestation project, balancing its various factors over the years, deciding on what to do when and where on the terrain, e.g. fertilizing, planting trees, or digging fire ditches. Meanwhile, adverse events, like wildfires or illegal logging, threaten your progress, creating a tension that gives the player a vivid experience of the complexity of the project. As you progress, several scores indicate the quality of your performance, most notably a biodiversity score, representing the amount and variety of trees in the forest. In this way, players receive clear hints to strategize and face each situation with the appropriate measures to grow a biodiverse forest. We evaluated Benni’s Forest conducting a survey amongst players. The results confirm both an increased understanding of the challenges involved in reforestation efforts, and an increased sense of engagement of players with such projects.","Serious games; Games for change; Sustainable development; Reforestation; Rainforest","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.","","2023-03-20","","","Computer Graphics and Visualisation","","",""
"uuid:86b6baee-c5af-4e70-a3c8-8f2bf5fab46f","http://resolver.tudelft.nl/uuid:86b6baee-c5af-4e70-a3c8-8f2bf5fab46f","Train scheduling with flexible coupling and decoupling at stations for an urban rail transit line","Zhao, Kangqi (Beijing Jiaotong University); Wang, Yihui (Beijing Jiaotong University); Ding, Miaomiao (Beijing Jiaotong University); Li, Shukai (Beijing Jiaotong University); Quaglietta, E. (TU Delft Transport and Planning); Meng, Lingyun (Beijing Jiaotong University)","","2022","More and more people in big cities choose urban rail transit as the main means of public transportation. With the increasing unbalanced passenger flow in time and space, the traditional operation mode with fixed train formation (or composition) is difficult to satisfy the varying passenger demands. This paper distinguishes different train formations in urban rail transit, and specifies the definition and the operation process for flexible composition of trains. An integrated train scheduling problem with flexible train composition is proposed, where the key constraints for practical train operation and the utilization of rolling stocks are considered. These constraints involve turnaround constraints, flexible train formation constraints, headway constraints and passenger flow constraints. The resulting problem is a mixed integer nonlinear programming problem, which can be transformed into a mixed integer linear programming problem and then be solved using existing optimization solvers, e.g., CPLEX. Based on the practical infrastructure and passenger demand data of the Beijing Daxing International Airport Express, a set of case studies is carried out to demonstrate the effectiveness of the presented model and solution approach. The computational results show that the train schedule with flexible train compositions can largely reduce the number of waiting passenger when compared with the train schedules with fixed train compositions and with multiple train compositions.","","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: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:3b56e736-efbd-4dd1-8788-533d33217389","http://resolver.tudelft.nl/uuid:3b56e736-efbd-4dd1-8788-533d33217389","Adaptive Decision Making at the Intersection for Autonomous Vehicles Based on Skill Discovery","He, Xianqi (Beijing Institute of Technology); Yang, Lin (Beijing Institute of Technology); Lu, Chao (Beijing Institute of Technology); Gong, Jianwei (Beijing Institute of Technology); Li, Z. (TU Delft Transport and Planning; Beijing Institute of Technology)","","2022","In urban environments, the complex and uncertain intersection scenarios are challenging for autonomous driving. To ensure safety, it is crucial to develop an adaptive decision making system that can handle the interaction with other vehicles. Manually designed model-based methods are reliable in common scenarios. But in uncertain environments, they are not reliable, so learning-based methods are proposed, especially reinforcement learning (RL) methods. However, current RL methods need retraining when the scenarios change. In other words, current RL methods cannot reuse accumulated knowledge. They forget learned knowledge when new scenarios are given. To solve this problem, we propose a hierarchical framework that can autonomously accumulate and reuse knowledge. The proposed method combines the idea of motion primitives (MPs) with hierarchical reinforcement learning (HRL). It decomposes complex problems into multiple basic subtasks to reduce the difficulty. The proposed method and other baseline methods are tested in a challenging intersection scenario based on the CARLA simulator. The intersection scenario contains three different subtasks that can reflect the complexity and uncertainty of real traffic flow. After offline learning and testing, the proposed method is proved to have the best performance among all methods.","","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:7e7bdccd-aa12-4b6a-a997-a19c4d1ad453","http://resolver.tudelft.nl/uuid:7e7bdccd-aa12-4b6a-a997-a19c4d1ad453","Self-Disclosure to a Robot ""In-the-Wild"": Category, Human Personality and Robot Identity","Neerincx, Anouk (Universiteit Utrecht); Edens, Chantal (Universiteit Utrecht); Broz, F. (TU Delft Interactive Intelligence); Li, Yanzhe (Student TU Delft); Neerincx, M.A. (TU Delft Interactive Intelligence)","","2022","Self-disclosures can be valuable and sensitive parts of the human-robot interaction. This paper investigates how far human's tendency to self-disclose depends on the topic of interaction, individual's personality and perceived robot identity (i.e., human-, robot- or animal-like). Robot's (Pepper) identity was shown in its self-disclosure, interaction behaviors (gestures, sound and voice), and ’’clothing"". In an""in-the- wild"" study at a science festival, 80 visitors interacted with one of these robot identities. When questioned by the robot, they disclosed more about their attitudes and opinions than about other categories. Significant correlations appeared between personality characteristics and the degree of self-disclosure, as well as differences in self-disclosure categories. The different robot identities showed no effects on disclosures.","","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.","","2023-03-30","","","Interactive Intelligence","","",""
"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:47a3bca4-3f36-4a4c-b531-164b0a7607fc","http://resolver.tudelft.nl/uuid:47a3bca4-3f36-4a4c-b531-164b0a7607fc","Label-Only Membership Inference Attack against \\Node-Level Graph Neural Networks","Conti, M. (TU Delft Cyber Security; University of Padua); Li, Jiaxin (University of Padua); Picek, S. (TU Delft Cyber Security); Xu, J. (TU Delft Cyber Security)","","2022","Graph Neural Networks (GNNs), inspired by Convolutional Neural Networks (CNNs), aggregate the message of nodes' neighbors and structure information to acquire expressive representations of nodes for node classification, graph classification, and link prediction. Previous studies have indicated that node-level GNNs are vulnerable to Membership Inference Attacks (MIAs), which infer whether a node is in the training data of GNNs and leak the node's private information, like the patient's disease history. The implementation of previous MIAs takes advantage of the models' probability output, which is infeasible if GNNs only provide the prediction label (label-only) for the input.
In this paper, we propose a label-only MIA against GNNs for node classification with the help of GNNs' flexible prediction mechanism, e.g., obtaining the prediction label of one node even when neighbors' information is unavailable. Our attacking method achieves around 60\% accuracy, precision, and Area Under the Curve (AUC) for most datasets and GNN models, some of which are competitive or even better than state-of-the-art probability-based MIAs implemented under our environment and settings. Additionally, we analyze the influence of the sampling method, model selection approach, and overfitting level on the attack performance of our label-only MIA. All of those three factors have an impact on the attack performance. Then, we consider scenarios where assumptions about the adversary's additional dataset (shadow dataset) and extra information about the target model are relaxed. Even in those scenarios, our label-only MIA achieves a better attack performance in most cases. Finally, we explore the effectiveness of possible defenses, including Dropout, Regularization, Normalization, and Jumping knowledge. None of those four defenses prevent our attack completely.","Machine learning; Membership inference attack; Graph neural networks","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Cyber Security","","",""
"uuid:8d49d09f-fcc4-41aa-8bd0-e438bfdb9dbc","http://resolver.tudelft.nl/uuid:8d49d09f-fcc4-41aa-8bd0-e438bfdb9dbc","Asymmetrical Modular Multilevel Converter with Sensorless Voltage Control for High-Quality Output","Li, Zhongxi (Duke University); Li, Z. (TU Delft Signal Processing Systems); Tashakor, Nima (Duke University); Peterchev, Angel (Duke University); Goetz, Stefan M. (Duke University; University of Cambridge)","","2022","The paper proposes an Asymmetrical Modular Multilevel Converter (AMMC) suitable for low/medium-voltage dc-ac conversions with very high output quality. The modules' dc-links of the AMMC are charged to a binary exponential sequence to produce a large number of output levels using only a few modules.The concept of using asymmetrical dc-links for high-quality output is not entirely new. However, the practicality of existing approaches is relatively low and challenged by the difficulties in maintaining the required dc-link voltages as well as suppressing their interaction with the output, which often requires multiple isolated dc/dc converters. We solve this problem by aligning the modules in the Marquardt MMC inverter module configuration that offers more control freedom, hence the term AMMC. Furthermore, we introduce a highly effective switched-inductor charge transfer and balancing mode between modules and even across arms. We accordingly modify the underlying conventional chopper modules so that the dc-link voltage control can be completely sensorless. The proposed AMMC is tested in a lab setup with four modules per arm reaching 32 output levels. In contrast to the low benefit of an additional module in MMC due to only linear improvement of the output granularity, each further module halves the finest voltage step. The components to maintain the graded voltage sequence and the underlying inductive charge transfer only a fraction (< 10%) of the load current so that relatively low-power devices can be used.","binary asymmetrical CHBs; DC/AC applications; high-definition; modular multilevel converters","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","","","Signal Processing Systems","","",""
"uuid:76884511-1a24-467b-8ff7-9a8d0e2c78c8","http://resolver.tudelft.nl/uuid:76884511-1a24-467b-8ff7-9a8d0e2c78c8","A 2m-Range 711uW Body Channel Communication Transceiver Featuring Dynamically-Sampling Bias-Free Interface Front End","Gu, Guanjie (Zhejiang University); Yang, Changgui (Zhejiang University); Li, Zhuhao (Zhejiang University); Feng, Xiangdong (Zhejiang University); Chang, Ziyi (Zhejiang University); Wang, Ting-Hsun (Zhejiang University); Zhang, Yunshan (Zhejiang University); Luo, Yuxuan (Zhejiang University); Zhang, Hong (Zhejiang University); Wang, Ping (Zhejiang University); Du, S. (TU Delft Electronic Instrumentation); Chen, Yong (University of Macau); Zhao, Bo (Zhejiang University)","","2022","Body Channel Communication (BCC) offers a low-loss signal transmission medium for ultra-low-power wearable devices on human body [1]. However, the effective communication range on human body is limited to less than 1m in the state-of-the-art BCC transceivers [2], where the signal loss at the interface of body surface and BCC receiver remains to be one of the main bottlenecks. The limited communication range has blocked the popularization in many WBAN applications, such as signal transmission from to an intelligent insole to smart watch [3]. Relative to the high impedance of human body [4], the lower input impedance of BCC receiver induces significant signal loss. To reduce the interface loss, conventional interface front end (IFE) of BCC receivers was designed to be with a high input impedance [5], but the DC voltage bias decreased both the input impedance and signal gain of IFE.","","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:552e8f69-26a0-4a2f-a82c-0896127ea735","http://resolver.tudelft.nl/uuid:552e8f69-26a0-4a2f-a82c-0896127ea735","PRIDE: A Privacy-Preserving Decentralised Key Management System","Kester, David (Student TU Delft); Li, T. (TU Delft Cyber Security); Erkin, Z. (TU Delft Cyber Security)","","2022","There is an increase in interest and necessity for an interoperable and efficient railway network across Europe, creating a key distribution problem between train and trackside entities’ key management centres (KMC). Train and trackside entities establish a secure session using symmetric keys (KMAC) loaded beforehand by their respective KMC using procedures that are not scalable and prone to operational mistakes. A single system would simplify the KMAC distribution between KMCs; nevertheless, it is difficult to place the responsibility for such a system for the whole European area within one central organization. A single system could also expose relationships between KMCs, revealing information, such as plans to use an alternative route or serve a new region, jeopardizing competitive advantage. This paper proposes a scalable and decentralised key management system that allows KMC to share cryptographic keys using transactions while keeping relationships anonymous. Using non-interactive proofs of knowledge and assigning each entity a private and public key, private key owners can issue valid transactions while all system actors can validate them. Our performance analysis shows that the proposed system is scalable when a proof of concept is implemented with settings close to the expected railway landscape in 2030.","blockchain; key management; privacy-preserving; proofs of knowledge; ertms","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","","","Cyber Security","","",""
"uuid:a5bf48ea-6c08-46f6-abc8-4c8a02805431","http://resolver.tudelft.nl/uuid:a5bf48ea-6c08-46f6-abc8-4c8a02805431","Progressive Damage Accumulation Process of CFRP Cross-Ply Laminates during the Early Fatigue Life","Li, X. (TU Delft Structural Integrity & Composites); Benedictus, R. (TU Delft Structural Integrity & Composites); Zarouchas, D. (TU Delft Structural Integrity & Composites)","Vassilopoulos, Anastasios P. (editor); Michaud, Véronique (editor)","2022","The present work aims at investigating the progressive damage accumulation process of CFRP laminates in an interactive scheme, with a special focus on the early fatigue life where mainly matrix-dominant damage accumulates and stiffness degrades significantly. An in-situ damage monitoring system, containing edge observation, digital image correlation and acoustic emission techniques, was established to characterize and quantify the accumulation of transverse cracks and delamination. Two cross-ply configurations ([0/902]s and [02/904]s) and different stress levels were involved in the experimental campaign. Dependent crack ratio was proposed to reflect the interaction among transverse cracks, and saturated crack density was used to represent the interactive level between transverse cracks and delamination. Results showed that generation of transverse cracks and their interaction govern the early fatigue damage accumulation of the [0/902]s laminates, while not only the interaction among cracks but also the interaction between both damage mechanisms were observed for the [02/904]s laminates.","Delamination; Fatigue damage; Stiffness degradation; Transverse crack","en","conference paper","EPFL Lausanne, Composite Construction Laboratory","","","","","","","","","","Structural Integrity & Composites","","",""
"uuid:2ab49dee-db85-4506-850b-f44e67aa808c","http://resolver.tudelft.nl/uuid:2ab49dee-db85-4506-850b-f44e67aa808c","Metadata Representations for Queryable ML Model Zoos","Li, Z. (TU Delft Web Information Systems); Hai, R. (TU Delft Web Information Systems); Bozzon, A. (TU Delft Human-Centred Artificial Intelligence); Katsifodimos, A (TU Delft Web Information Systems)","","2022","Machine learning (ML) practitioners and organizations are building model zoos of pre-trained models, containing metadata describing properties of the ML models and datasets that are useful for reporting, auditing, reproducibility, and interpretability purposes. The metatada is currently not standardised; its expressivity is limited; and there is no interoperable way to store and query it. Consequently, model search, reuse, comparison, and composition are hindered. In this paper, we advocate for standardized ML model metadata representation and management, proposing a toolkit supported to help practitioners manage and query that metadata.","","en","conference paper","","","","","","","","","","","Web Information Systems","","",""
"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:856a5681-2d68-4f42-9cc6-71c26a06b10e","http://resolver.tudelft.nl/uuid:856a5681-2d68-4f42-9cc6-71c26a06b10e","Prediction-Based Reachability Analysis for Collision Risk Assessment on Highways","Wang, X. (TU Delft Learning & Autonomous Control); Li, Z. (TU Delft Transport and Planning; Beijing Institute of Technology); Alonso-Mora, J. (TU Delft Learning & Autonomous Control); Wang, M. (TU Delft Transport and Planning; Technische Universität Dresden)","","2022","Real-time safety systems are crucial components of intelligent vehicles. This paper introduces a prediction-based collision risk assessment approach on highways. Given a point mass vehicle dynamics system, a stochastic forward reachable set considering two-dimensional motion with vehicle state probability distributions is firstly established. We then develop an acceleration prediction model, which provides multi-modal probabilistic acceleration distributions to propagate vehicle states. The collision probability is calculated by summing up the probabilities of the states where two vehicles spatially overlap. Simulation results show that the prediction model has superior performance in terms of vehicle motion position errors, and the proposed collision detection approach is agile and effective to identify the collision in cut-in crash events.","Road transportation; Intelligent vehicles; Simulation; Stochastic processes; Predictive models; Probability distribution; Risk 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.","","2023-01-19","","Transport and Planning","Learning & Autonomous Control","","",""
"uuid:c0215473-7802-448f-88fa-9138fc8759dc","http://resolver.tudelft.nl/uuid:c0215473-7802-448f-88fa-9138fc8759dc","The artificial-social-agent questionnaire: Establishing the long and short questionnaire versions","Fitrianie, S. (TU Delft Interactive Intelligence); Bruijnes, M. (TU Delft Interactive Intelligence; Universiteit Utrecht; School of Business Administration, Northeastern University); Li, Fengxiang; Abdulrahman, A. (TU Delft Interactive Intelligence); Brinkman, W.P. (TU Delft Interactive Intelligence)","","2022","We present the ASA Questionnaire, an instrument for evaluating human interaction with an artificial social agent (ASA), resulting from multi-year efforts involving more than 100 Intelligent Virtual Agent (IVA) researchers worldwide. It has 19 measurement constructs constituted by 90 items, which capture more than 80% of the constructs identified in empirical studies published in the IVA conference 2013 - 2018. This paper reports on construct validity analysis, specifically convergent and discriminant validity of initial 131 instrument items that involved 532 crowd-workers who were asked to rate human interaction with 14 different ASAs. The analysis included several factor analysis models and resulted in the selection of 90 items for inclusion in the long version of the ASA questionnaire. In addition, a representative item of each construct or dimension was selected to create a 24-item short version of the ASA questionnaire. Whereas the long version is suitable for a comprehensive evaluation of human-ASA interaction, the short version allows quick analysis and description of the interaction with the ASA. To support reporting ASA questionnaire results, we also put forward an ASA chart. The chart provides a quick overview of the agent profile.","artificial social agent; construct validity; evaluation instrument; questionnaire; user study","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Interactive Intelligence","","",""
"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:00558f86-62db-4d5f-98a7-8811200ac67b","http://resolver.tudelft.nl/uuid:00558f86-62db-4d5f-98a7-8811200ac67b","Deep confocal fluorescence microscopy with single-photon superconducting nanowire detector","Xia, Fei (Cornell University College of Engineering; Sorbonne Université); Gevers, Monique (Single Quantum); Fognini, Andreas (Single Quantum); Mok, Aaron T. (Cornell University College of Engineering); Li, Bo (Cornell University College of Engineering); Akabri, Najva (Cornell University College of Engineering); Esmaeil Zadeh, I.Z. (TU Delft ImPhys/Optics; Single Quantum); Qin-Dregely, Y. (Single Quantum); Xu, Chris (Cornell University College of Engineering)","Itzler, Mark A. (editor); Bienfang, Joshua C. (editor); McIntosh, K. Alex (editor)","2022","Using short-wave infrared wavelength advantages, we demonstrate one-photon fluorescence confocal microscopy of adult mouse brains with penetration depths up to 1.7mm. This is achieved by labeling quantum dots with 1300 nm excitation and 1700 nm emission and detecting them with a single-photon superconducting nanowire detector.","","en","conference paper","SPIE","","","","","","","","","","ImPhys/Optics","","",""
"uuid:cf2152af-a575-4c0d-aa5f-89bc0b1cee7f","http://resolver.tudelft.nl/uuid:cf2152af-a575-4c0d-aa5f-89bc0b1cee7f","Workshop on Multimodal Motion Sickness Detection and Mitigation Methods for Car Journeys","Pöhlmann, Katharina Margareta Theresa (University of Glasgow); Li, Gang (University of Glasgow); Dam, Abhraneil (Virginia Polytechnic Institute and State University); Wang, Yu Kai (University of Technology Sydney); Wei, Chun Shu (National Yang Ming Chiao Tung University, Hsinchu); Brietzke, Adrian (Volkswagen AG); Papaioannou, G. (TU Delft Intelligent Vehicles)","","2022","The mass adoption of automated vehicles in the near future will benefit safety (of occupants and pedestrians), the environment (low emissions), and society (accessibility, on-demand travel). There are, however, still challenges that need to be addressed, with one of the most crucial being motion sickness. In automated vehicles, the interior could be transformed into a living room or a working space, allowing occupants to spend their time with non-driving activities. These changes are likely to provoke, and increase, motion sickness incidence. To that end, this workshop will explore the current state of motion sickness detection and mitigation methods from different angles (e.g., closed-loop detection, multimodal motion cues,etc.) through expert talks and reflections, followed by discussions. The workshop will develop an agenda for motion sickness research in automated vehicles, facilitate new research ideas and fruitful collaborations.","Automated Vehicles; Comfort; Detection; Mitigation; Motion Sickness","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","","","Intelligent Vehicles","","",""
"uuid:5b4de004-7a15-4b61-947d-2873b57ff406","http://resolver.tudelft.nl/uuid:5b4de004-7a15-4b61-947d-2873b57ff406","Two for the price of one: communication efficient and privacy-preserving distributed average consensus using quantization","Li, Qiongxiu (Aalborg University); Lopuhaä-Zwakenberg, Milan (University of Twente); Heusdens, R. (TU Delft Signal Processing Systems); Christensen, Mads Græsbøll (Aalborg University)","","2022","Both communication overhead and privacy are main concerns in designing distributed computing algorithms. It is very challenging to address them simultaneously as encryption methods required for privacy-preservation often incur high communication costs. In this paper, we argue that there is a fundamental link between communication efficiency and privacy-preservation through quantization. Based on the observation that quantization, which can save communication bandwidth, will introduce error into the system, we propose a novel privacy-preserving distributed average consensus algorithm which uses the error introduced by quantization as noise to obfuscate the private data for protecting it from being revealed to others. Similar to existing differential privacy based approaches, the proposed approach is robust and has low computational complexity in dealing with two widely considered adversary models: the passive and eavesdropping adversaries. In addition, the method is generally applicable to many distributed optimizers, like PDMM and (generalized) ADMM. We conduct numerical simulations to validate that the proposed approach has superior performance compared to existing algorithms in terms of accuracy, communication bandwidth and privacy.","ADMM; communication; Distributed average consensus; PDMM; privacy; wireless sensor networks","en","conference paper","European Signal Processing Conference, EUSIPCO","","","","","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.","","2022-07-01","","","Signal Processing Systems","","",""
"uuid:312dbef7-d7ed-429a-aeb7-42a9f5ec561b","http://resolver.tudelft.nl/uuid:312dbef7-d7ed-429a-aeb7-42a9f5ec561b","The Co-Creation Space: Supporting Asynchronous Artistic Co-creation Dynamics","Striner, Alina (Centrum Wiskunde & Informatica (CWI)); Röggla, Thomas (Centrum Wiskunde & Informatica (CWI)); Zorrilla, Mikel (Vicomtech, Donostia-San Sebastian); Cabrero Barros, Sergio (Vicomtech, Donostia-San Sebastian); Masneri, Stefano (Vicomtech, Donostia-San Sebastian); Rivas Pagador, Héctor (Vicomtech, Donostia-San Sebastian); Calvis, Irene (Liceu Barcelona); Li, Jie (Centrum Wiskunde & Informatica (CWI)); Cesar, Pablo (TU Delft Multimedia Computing; Centrum Wiskunde & Informatica (CWI))","","2022","Artistic co-creation empowers communities to shape their narratives, however HCI research does not support this multifaceted discussion and reflection process. In the context of community opera, we consider how to support co-creation through the design, implementation, and initial evaluation of the Co-Creation Space (CCS) to help community artists 1) generate raw artistic ideas, and 2) discuss and reflect on the shared meaning of those ideas. This work describes our user-centered process to gather requirements and design the tool, and validates its' usability with 6 community opera participants. Our findings support the value of our tool for group discussion and personal reflection during the creative process.","Art; Asynchronous; Co-creation","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","","","Multimedia Computing","","",""
"uuid:35bef57d-22e9-4202-b8ca-d0ccca6d5edd","http://resolver.tudelft.nl/uuid:35bef57d-22e9-4202-b8ca-d0ccca6d5edd","The feasibility of csem monitoring in gas hydrate production of the range of porosity and saturation","Li, Y. (Beijing University of Technology; Student TU Delft); Lu, H. (Peking University; Beijing University of Technology); Wang, L. (Beihang University); Eltayieb, M.F.M.I. (TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics)","Flowers, Simon (editor)","2022","Natural gas hydrates production tests over the last two decades has sown that production is not without risks. Indirect effects in the sedimentary rocks of phase changes are changes in porosity, permeability, and saturation. From a field production test site, porosity changes in the range of 15% to 19% and saturation from 5% to 60% were reported. Monitoring is in principle possible using an electromagnetic survey with a downhole vertical electric source and a horizontal electric field receiver on the seafloor. Computed model responses over a wide frequency range and for many depth locations of an electric current source show that both changes can be detected. Best detectability occurs when the current source is below the reservoir layer in case of changes differences can be detected above, inside and below the reservoir layer at frequencyies below 10 Hz. At a source operating frequency of 0.1 Hz maximum response difference between the two values in saturation occur when the source is 20 m above the top of the reservoir layer unil 100 m below the bottom. Only below the top of the reservoir there is almost no difference in the electric field amplitude between the two saturation levels below 10 Hz.","","en","conference paper","EAGE","","","","","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","","","Applied Geophysics and Petrophysics","","",""
"uuid:259442d8-cfc6-48e7-b548-8675e9695042","http://resolver.tudelft.nl/uuid:259442d8-cfc6-48e7-b548-8675e9695042","Graph Encryption for Shortest Path Queries with k Unsorted Nodes","Li, Meng (Hefei University of Technology); Gao, Jianbo (Hefei University of Technology); Zhang, Zijian (Beijing Institute of Technology); Fu, Chaoping (Huaqiao University); Lal, C. (TU Delft Cyber Security); Conti, M. (Università degli Studi di Padova)","","2022","Shortest distance queries over large-scale graphs bring great benefits to various applications, i.e., save planning time and travelling expenses. To protect the sensitive nodes and edges in the graph, a user outsources an encrypted graph to an untrusted server without losing the query ability. However, no prior work has considered the user requirement of the shortest path with k unsorted nodes. In particular, we are concerned with how to securely find the shortest path by passing k nodes that do not have a fixed traverse order. To solve the problems, we propose Gespun (stands for Graph encryption for shortest path queries with k unordered nodes). It includes an oracle encryption scheme that is provably secure against the semi-honest server. Specifically, we compute the shortest paths and distances for all nodes locally to obtain path-distance oracles. We transform the shortest paths to a sequence of secure codes by using a pseudo-random permutation to protect the structure privacy. We encrypt the shortest distance by using additively homomorphic encryption. Second, we pack the oracles in link-list nodes and store them in an array-based dictionary after another permutation. Next, we construct a search graph to compute the shortest path while guaranteeing that the path passes the required k nodes. We formally prove that Gespun is adaptively semantically-secure in the random oracle. We implement a prototype of Gespun and evaluate its performance. Experiments results demonstrate that Gespun is efficient, e.g., a query over 6301 nodes, 20777 edges, and 5 unsorted nodes only needs 483 ms to get queried results. We believe that our research problem span new research that soon promotes a new line of graph encryption schemes.","Graph encryption; Security; Shortest distance query; Unsorted nodes","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","","","Cyber Security","","",""
"uuid:d9cc6841-58ff-464c-a31d-8955e977ec0d","http://resolver.tudelft.nl/uuid:d9cc6841-58ff-464c-a31d-8955e977ec0d","Between Tradition and Modernity: Western urban planning and street improvement projects in Hankou (1889-1937)","Ren, X. (Southeast University); Li, Baihao (Southeast University); Hein, C.M. (TU Delft History, Form & Aesthetics)","","2022","This article examines street improvement projects in Hankou's case for unearthing the contribution of Chinese political elites and planers in exchanging planning concepts and technologies from the West to China. Aiming to realize the Modern Metropolis, which Sun Yat-sen proposed in the fundamentals of national reconstruction, Chinese political elites and planers selected, borrowed, and imported western planning ideas to transform traditional Hankou city by implementing street improvement projects. Using the case of street improvement of Hankou during the Late Qing period(1889-1911), Early Republic China period(1911-1926), and Municipal Government period(1926-1937) as case studies, this article examines street improvement projects which authorities developed for Hankou in three different periods. By analyzing planning concepts, street plans(both realized and planned), and management regulations of these projects, the paper argues that improvement projects aimed to develop economic and industrial and improve public hygiene. Furthermore, the Chinese political and planning elites imported European and American design principles and practiced them in the Hankou local context for their own needs. In conclusion, the built environment showed hybridization features after implementing continuous planning schemes.","Hankou; urban transformation; planning history; street improvement; modernity","en","conference paper","Delft University of Technology","","","","","","","","","","History, Form & Aesthetics","","",""
"uuid:50c5b6b7-cb44-4a7a-b365-1f1dbe8c917f","http://resolver.tudelft.nl/uuid:50c5b6b7-cb44-4a7a-b365-1f1dbe8c917f","A Human-Centered Design Procedure for Conceptualization Using Virtual Reality Prototyping Applied in an Inflight Lavatory","Li, M. (TU Delft Applied Ergonomics and Design; Xi’an Jiaotong University); Aschenbrenner, D. (TU Delft Mechatronic Design); van Tol, D.H. (Student TU Delft); van Eijk, D.J. (TU Delft Applied Ergonomics and Design); Vink, P. (TU Delft Materials and Manufacturing)","Black, Nancy L. (editor); Neumann, W. Patrick (editor); Noy, Ian (editor)","2022","For designing large-scale products like an airplane, engaging end-users in the concept phase is difficult. However, early user evaluation is important to choose the path which fits the user’s needs best. In particular, comfort-related assessments are difficult to conduct with digital models that are shown on a desktop PC application. Digital Human Modelling (DHM) plays a role in postural comfort analysis, while the subjective comfort feedback still largely relied on consulting with end-users. This paper applies a human-centered design process and analyses the advantages and disadvantages of using VR prototypes for involving users during concept design. This study focused on using VR prototypes for concept selection and verification based on comfort assessment with potential end-users. The design process started with an online questionnaire for identifying the quality of the design elements (Step 1 online study). Then, alternative concepts were implemented in VR, and users evaluated these concepts via a VR headset (Step 2 Selection study). Finally, the research team redesigned the final concept and assessed it with potential users via a VR headset (Step 3 Experience study). Every design element contributed positively to the long-haul flight comfort, especially tap-basin height, storage, and facilities. The male and female participants had different preferences on posture, lighting, storage, and facilities. The final prototype showed a significantly higher comfort rate than the original prototypes. The first-person immersion in VR headsets helps to identify the nuances between concepts, thus supports better decision-making via collecting richer and more reliable user feedback to make faster and more satisfying improvements.","Concept design; First-person immersion; Human-centered Design; Virtual prototyping; Virtual reality","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.","","2023-07-01","","","Applied Ergonomics and Design","","",""
"uuid:1866962d-4162-405f-a161-122bb9bd8900","http://resolver.tudelft.nl/uuid:1866962d-4162-405f-a161-122bb9bd8900","A Finite Element Thermomechanical Analysis of Polygonal Wear","He, C. (TU Delft Railway Engineering); Yang, Z. (TU Delft Railway Engineering); Zhang, P. (TU Delft Railway Engineering); Li, S. (TU Delft Railway Engineering); Naeimi, M. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering)","Orlova, Anna (editor); Cole, David (editor)","2022","Polygonal wear is a common type of damage on the railway wheel tread, which could induce wheel-rail impacts and further components failure. This study presents a finite element (FE) thermomechanical model to investigate the causes of wheel polygonal wear. The FE model is able to cope with three possible causes of polygonal wear: thermal effect, initial defects, and structural dynamics. To analyse the influences of the three causes on wheel-rail contact stress and wear depth, different material properties (i.e., elastic, elasto-plastic, thermo-elasto-plastic with thermal softening), and wheel profiles (i.e., round and polygonal) were used in the FE model. The simulation indicates that a high temperature up to 264.20 ℃ could be induced by full-slip wheel-rail rolling contact when the polygonal profile is used. The thermal effect, similar to that induced by tread brake, may then have a significant influence on wheel-rail contact stress and wear depth. In addition, the involvement of initial defects, i.e., polygonal profile, causes wheel-rail impact contact and remarkably increases the contact stress and wear. By reliably considering all the three possible causes, the proposed FE model is believed promising for further explaining the generation mechanisms of wheel polygonal wear.","Finite element model; Initial defects; Polygonal wear; Thermal effect","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.","","2023-07-01","","","Railway Engineering","","",""
"uuid:c1df60a5-07da-4513-a5d4-f57cc7dd05ce","http://resolver.tudelft.nl/uuid:c1df60a5-07da-4513-a5d4-f57cc7dd05ce","Repetitive, Oblivious, and Unlinkable SkNN Over Encrypted-and-Updated Data on Cloud","Li, Meng (Hefei University of Technology); Zhang, Mingwei (Hefei University of Technology); Gao, Jianbo (Hefei University of Technology); Lal, C. (TU Delft Cyber Security); Conti, M. (TU Delft Cyber Security; Università degli Studi di Padova); Alazab, Mamoun (Charles Darwin University)","Alcaraz, Cristina (editor); Chen, Liqun (editor); Li, Shujun (editor); Samarati, Pierangela (editor)","2022","Location-Based Services (LBSs) depend on a Service Provider (SP) to store data owners’ geospatial data and to process data users’ queries. For example, a Yelp user queries the SP to retrieve the k nearest Starbucks by submitting her/his current location. It is well-acknowledged that location privacy is vital to users and several prominent Secure k Nearest Neighbor (SkNN) query processing schemes are proposed. We observe that no prior work addresses the requirement of repetitive query after index update and its privacy issue, i.e., how to match a data item from the cloud repetitively in an oblivious and unlinkable manner. Meanwhile, a malicious SP may skip some data items and recommend others due to unfair competition. In this work, we formally define the repetitive query and its privacy objectives and present an Repetitive, Oblivious, and Unlinkable SkNN scheme ROU. Specifically, we design a multi-level structure to organize locations to further improve search efficiency. Second, we integrate data item identity into the framework of existing SkNN query processing. Data owners encrypt their data item identity and location information into a secure index, and data users encrypt a customized identity range of a previously retrieved data item and location information into a token. Next, the SP uses the token to query the secure index to find the specific data item via privacy-preserving range querying. We formally prove the privacy of ROU in the random oracle model. We build a prototype based on a server to evaluate the performance with a real-world dataset. Experimental results show that ROU is efficient and practical in terms of computational cost, communication overhead, and result verification.","Cloud computing; Privacy; Repetitive query; SkNN","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.","","","","","Cyber Security","","",""
"uuid:a207a943-0e56-4dbb-bfde-2d668a43b81a","http://resolver.tudelft.nl/uuid:a207a943-0e56-4dbb-bfde-2d668a43b81a","Model-to-Image Registration via Deep Learning towards Image-Guided Endovascular Interventions","Li, Z. (TU Delft Medical Instruments & Bio-Inspired Technology; Politecnico di Milano); Mancini, Maria Elisabetta (IRCCS); Monizzi, Giovanni (IRCCS); Andreini, Daniele (IRCCS; University of Milan); Ferrigno, Giancarlo (Politecnico di Milano); Dankelman, J. (TU Delft Medical Instruments & Bio-Inspired Technology); De Momi, Elena (Politecnico di Milano)","","2021","Cardiologists highlight the need for an intra-operative 3D visualization to assist interventions. The intra-operative 2D X-ray/Digital Subtraction Angiography (DSA) images in the standard clinical workflow limit cardiologists’ views significantly. Compared with image-to-image registration, model-to-image registration is an essential approach taking advantage of the reuse of pre-operative 3D models reconstructed from Computed Tomography Angiography (CTA) images. Traditional optimized-based registration methods suffer severely from high computational complexity. Moreover, the consequence of lacking ground truth for learning-based registration approaches should not be neglected. To overcome these challenges, we introduce a model-to-image registration framework via deep learning for image-guided endovascular catheterization. This work performs autonomous vessel segmentation from intra-operative fluoroscopy images via a deep residual U-net and a model-to-image matching via a convolutional neural network. For this study, image data were collected from 10 patients who performed Transcatheter Aortic Valve Implantation (TAVI) procedures. It was found that vessel segmentation of test data results in median values of Dice Similarity Coefficient, Precision, and Recall of (0.75, 0.58, 0.67) for femoral artery, and (0.71, 0.56, 0.74) for aortic root. The segmentation network behaves better than manual annotation, and it recognizes part of vessels that were not labeled manually. Image matching between the transformed moving image and the fixed image results in a median value of Recall of 0.90. The proposed approach achieves a good accuracy of vessel segmentation and a good recall value of model-to-image matching.","Endovascular Catheterization; Image-guided Interventions; Image Registration; Deep Learning; Convolutional Neural Network","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","","","Medical Instruments & Bio-Inspired Technology","","",""
"uuid:9f0918e0-cc1f-408f-b011-be5d05858683","http://resolver.tudelft.nl/uuid:9f0918e0-cc1f-408f-b011-be5d05858683","Influence of uncertainty on performance of opportunistic maintenance strategy for offshore wind farms","Li, M. (TU Delft Transport Engineering and Logistics); Jiang, X. (TU Delft Transport Engineering and Logistics); Carroll, James (University of Strathclyde); Negenborn, R.R. (TU Delft Transport Engineering and Logistics)","","2021","The increasing capacity of offshore wind energy around the world brings challenges in Operation and Maintenance (O&M) management. Over the past years, many studies have focused on developing sound maintenance strategies in order to minimize maintenance cost or maximize availability. One of the promising maintenance strategies is opportunistic maintenance due to its potential to combine maintenance activities and save maintenance efforts. In these models, a common assumption is made that input parameters are deterministic and maintenance decisions are made based on these assumed deterministic input parameters. However, offshore wind farm maintenance in the practical world is a complicated task where multiple types of uncertainty exist. These uncertainties may affect evaluation or output of the maintenance model, making maintenance decisions sub-optimal or even inappropriate. In this paper, a probabilistic simulation-based approach integrating an uncertainty module and a simulation module is proposed to study the influence of the uncertainties on maintenance performance. We identify the primary input parameters which should be considered as uncertainty but are simplified to be deterministic values in offshore wind energy maintenance models. These deterministic parameters are modelled as stochastic values in the uncertainty module to generate uncertainty scenarios. The simulation module for opportunistic maintenance is developed to quantity the expected maintenance cost and lost production. The most influential uncertainties are identified. Valuable information and suggestions are provided to offshore wind farm owners for future decision-making and project management.","maintenance strategy; uncertainty; offshore wind energy; operation and maintenance","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.","","2022-08-15","","","Transport Engineering and Logistics","","",""
"uuid:b592bef4-2a74-410d-9118-080d75f09dc1","http://resolver.tudelft.nl/uuid:b592bef4-2a74-410d-9118-080d75f09dc1","Nonlinear model predictive control for improving range-based relative localization by maximizing observability","Li, S. (TU Delft Control & Simulation); de Wagter, C. (TU Delft Control & Simulation); de Croon, G.C.H.E. (TU Delft Control & Simulation)","Martinez-Carranza, Jose (editor)","2021","Wireless ranging measurements have been proposed for enabling multiple Micro Air Vehicles (MAVs) to localize with respect to each other. However, the high-dimensional relative states are weakly observable due to the scalar distance measurement. Hence, the MAVs have degraded relative localization and control performance under unobservable conditions as can be deduced by the Lie derivatives. This paper presents a nonlinear model predictive control (NMPC) by maximizing the determinant of the observability matrix in order to generate optimal control inputs, which also satisfy constraints including multirobot tasks, input limitation, and state bounds. Simulation results validate the localization and control efficacy of the proposed MPC method for range-based multi-MAV systems with weak observability, which has faster convergence time and more accurate localization compared to previously proposed random motions.","","en","conference paper","","","","","","","","","","","Control & Simulation","","",""
"uuid:b7d58766-6208-4d3d-bc04-ad7e72a6b25a","http://resolver.tudelft.nl/uuid:b7d58766-6208-4d3d-bc04-ad7e72a6b25a","Questionnaire Items for Evaluating Artificial Social Agents - Expert Generated, Content Validated and Reliability Analysed","Fitrianie, S. (TU Delft Interactive Intelligence); Bruijnes, M. (TU Delft Interactive Intelligence); Li, Fengxiang (Northestern University, Shenyang); Brinkman, W.P. (TU Delft Interactive Intelligence)","","2021","In this paper, we report on the multi-year Intelligent Virtual Agents (IVA) community effort, involving more than 90 researchers worldwide, researching the IVA community interests and practice in evaluating human interaction with an artificial social agent (ASA). The joint efforts have previously generated a unified set of 19 constructs that capture more than 80% of constructs used in empirical studies published in the IVA conference between 2013 to 2018. In this paper, we present expert-content-validated 131 questionnaire items for the constructs and their dimensions, and investigate the level of reliability. We establish this in three phases. Firstly, eight experts generated 431 potential construct items. Secondly, 20 experts rated whether items measure (only) their intended construct, resulting in 207 content-validated items. Next, a reliability analysis was conducted, involving 192 crowd-workers who were asked to rate a human interaction with an ASA, which resulted in 131 items (about 5 items per measurement, with Cronbach's alpha ranged [.60 - .87]). These are the starting points for the questionnaire instrument of human-ASA interaction.","Artificial social agent; evaluation instrument; questionnaire; reliability analysis; user study","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Interactive Intelligence","","",""
"uuid:b8cdb87b-4dd2-4b6b-8fad-0b70aca8ce02","http://resolver.tudelft.nl/uuid:b8cdb87b-4dd2-4b6b-8fad-0b70aca8ce02","Facial Feedback for Reinforcement Learning: A Case Study and Offline Analysis Using the TAMER Framework","Li, Guangliang (Ocean University of China); Whiteson, Shimon (University of Oxford); Dibeklioğlu, Hamdi (Bilkent University); Hung, H.S. (TU Delft Pattern Recognition and Bioinformatics)","","2021","Interactive reinforcement learning provides a way for agents to learn to solve tasks from evaluative feedback provided by a human user. Previous research showed that humans give copious feedback early in training but very sparsely thereafter. In this paper, we investigate the potential of agent learning from trainers’ facial expressions via interpreting them as evaluative feedback. To do so, we implemented TAMER which is a popular interactive reinforcement learning method in a reinforcement-learning benchmark problem — Infinite Mario, and conducted the first large-scale study of TAMER involving 561 participants. With designed CNN-RNN model, our analysis shows that telling trainers to use facial expressions and competition can improve the accuracies for estimating positive and negative feedback using facial expressions. In addition, our results with a simulation experiment show that learning solely from predicted feedback based on facial expressions is possible and using strong/effective prediction models or a regression method, facial responses would significantly improve the performance of agents. Furthermore, our experiment supports previous studies demonstrating the importance of bi-directional feedback and competitive elements in the training interface.","Facial Feedback; Implicit Feedback; Interactive; Reinforcement Learning","en","conference paper","International Foundation for Autonomous Agents and Multiagent Systems (IFAAMAS)","","","","","","","","","","Pattern Recognition and Bioinformatics","","",""
"uuid:7a9fdc32-876d-4ee9-ba68-9447130d0bc7","http://resolver.tudelft.nl/uuid:7a9fdc32-876d-4ee9-ba68-9447130d0bc7","Two-way Augmented Reality Co-location Under Telemedicine Context","Li, M. (TU Delft Applied Ergonomics and Design; Xi’an Jiaotong University); Slijkhuis, Tom (Royal Philips); Huigen, Remko (Maritime Medical Applications BV); Albayrak, A. (TU Delft Applied Ergonomics and Design); van Eijk, D.J. (TU Delft Applied Ergonomics and Design)","O'Conner, L. (editor)","2021","The medical care responsibilities are often on the shoulders of nonprofessionals such as captains who are equipped with forty hours of designated training every five years. However, this training is neither enough for the captains to handle medical incidents nor releases their stress during the treatment. Currently, captains have very limited support from a medical expert, only via phone call or email from the Radio Medical Services. Thus, the authors explored that how the two-way augmented reality (AR) can support the collaboration between captains and doctors for a better quality of care. A Human-Centred Design approach is applied in this study, including field study and user testing. The lean user experience method was applied with fast prototyping-testing loops. The main findings are AR played an essential role to boost confidence on the captain's side, and the real value of AR is in supporting medical skills like suturing and abdominal searching. This study serves as a pilot research, thus it was limited by small sample size and qualitative method. Improving the communication between the captains and doctors is key for future studies.","Collaborative augmented reality; co-location; telemedicine; remote expert; Human-centered computing","en","conference paper","IEEE","","","","","Accepted Author Manuscript","","","","","Applied Ergonomics and Design","","",""
"uuid:cdc8cfa6-765a-4ced-a5d8-57b70d9b8d02","http://resolver.tudelft.nl/uuid:cdc8cfa6-765a-4ced-a5d8-57b70d9b8d02","A molecular dynamics study of N-A-S-H gel with various Si/Al ratios","Chen, Y. (TU Delft Materials and Environment; South China University of Technology); Dolado, Jorge S. (Centro Mixto CSIC-UPV/EHU; Donostia International Physics Center); Yin, Suhong (South China University of Technology); Yu, Qijun (South China University of Technology); Kostiuchenko, A. (TU Delft Materials and Environment); Li, Z. (TU Delft Materials and Environment); Ye, G. (TU Delft Materials and Environment; Universiteit Gent)","Ye, Guang (editor); Dong, Hua (editor); Liu, Jiaping (editor); Schlangen, Erik (editor); Miao, Changwen (editor)","2021","The understanding of sodium aluminosilicate hydrate (N-A-S-H) gel is still limited due to its complex and amorphous structure. Recently, molecular dynamics simulation has provided a unique opportunity to better understand the structure of N-A-S-H gel from nanoscale. In this work, the N-A-S-H gel structure was obtained by simulating the polymerization of Si and Al monomers by molecular dynamics. The simulated polymerization process is in good agreement with the experimental results especially in terms of the reaction rate of Si and Al species. The atomic structural features of the N-A-S-H gel were analyzed in terms of bond length and bond angle information, simulated X-ray diffraction (XRD) and Qn distribution. A significant finding is the existence of pentacoordinate Al in all simulated N-A-S-H structures, indicating that pentacoordinate Al in geopolymer does not only come from raw material. Besides, the results show that a smaller Si/Al ratio led to a more crosslinked and compacted structure of N-A-S-H gel.","molecular dynamics; N-A-S-H gel; atomic structures; Si/Al ratio","en","conference paper","Delft University of Technology","","","","","","","","","","Materials and Environment","","",""
"uuid:401c92a1-bf10-46e7-b709-fc17294e9a21","http://resolver.tudelft.nl/uuid:401c92a1-bf10-46e7-b709-fc17294e9a21","Mitigating the autogenous shrinkage of alkali-activated slag by internal curing","Li, Z. (TU Delft Materials and Environment); Wyrzykowski, Mateusz (Swiss Federal Laboratories for Materials Science and Technology (Empa)); Dong, H. (TU Delft Materials and Environment); Zhang, Shizhe (TU Delft Materials and Environment); Lura, Pietro (ETH Zürich; Swiss Federal Laboratories for Materials Science and Technology (Empa)); Ye, G. (TU Delft Materials and Environment; Universiteit Gent)","Ye, Guang (editor); Dong, Hua (editor); Liu, Jiaping (editor); Schlangen, Erik (editor); Miao, Changwen (editor)","2021","Alkali activated slag (AAS) has shown promising potential to replace ordinary Portland cement as a binder material. Synthesized from industrial by-products, AAS can show high strength, thermal resistance and good durability. However, AAS has been reported to exhibit high autogenous shrinkage. Autogenous shrinkage is a critical issue for building materials since it can induce micro- or macro-cracking when the materials are under restrained conditions. Hence, this work aims at mitigating the autogenous shrinkage of AAS by means of internal curing. The influences of internal curing on microstructure formation and autogenous shrinkage are investigated. The results show that internal curing provided by superabsorbent polymers is a promising way to reduce the autogenous shrinkage of AAS.","Internal curing; autogenous shrinkage; alkali-activated materials; slag; superabsorbent polymers (SAP)","en","conference paper","Delft University of Technology","","","","","","","","","","Materials and Environment","","",""
"uuid:10f51376-66a9-4e33-b491-d2fb31adf0c7","http://resolver.tudelft.nl/uuid:10f51376-66a9-4e33-b491-d2fb31adf0c7","Leave No User Behind: Towards Improving the Utility of Recommender Systems for Non-mainstream Users","Li, Roger Zhe (TU Delft Multimedia Computing); Urbano, Julián (TU Delft Multimedia Computing); Hanjalic, A. (TU Delft Intelligent Systems)","","2021","In a collaborative-filtering recommendation scenario, biases in the data will likely propagate in the learned recommendations. In this paper we focus on the so-called mainstream bias: the tendency of a recommender system to provide better recommendations to users who have a mainstream taste, as opposed to non-mainstream users. We propose NAECF, a conceptually simple but effective idea to address this bias. The idea consists of adding an autoencoder (AE) layer when learning user and item representations with text-based Convolutional Neural Networks. The AEs, one for the users and one for the items, serve as adversaries to the process of minimizing the rating prediction error when learning how to recommend. They enforce that the specific unique properties of all users and items are sufficiently well incorporated and preserved in the learned representations. These representations, extracted as the bottlenecks of the corresponding AEs, are expected to be less biased towards mainstream users, and to provide more balanced recommendation utility across all users. Our experimental results confirm these expectations, significantly improving the recommendations for nonmainstream users while maintaining the recommendation quality for mainstream users. Our results emphasize the importance of deploying extensive content-based features, such as online reviews, in order to better represent users and items to maximize the debiasing effect.","mainstream bias; recommender systems; user fairness","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","Intelligent Systems","Multimedia Computing","","",""
"uuid:e30ef7e1-1029-474d-93f0-33b42c675e9a","http://resolver.tudelft.nl/uuid:e30ef7e1-1029-474d-93f0-33b42c675e9a","A-DDPG: Attention Mechanism-based Deep Reinforcement Learning for NFV","He, Nan (Beijing Institute of Technology); Yang, S. (Beijing Institute of Technology); Li, Fan (Beijing Institute of Technology); Trajanovski, S. (Microsoft Corporation); Kuipers, F.A. (TU Delft Embedded Systems); Fu, Xiaoming (University of Göttingen)","","2021","The efficacy of Network Function Virtualization (NFV) depends critically on (1) where the virtual network functions (VNFs) are placed and (2) how the traffic is routed. Unfortunately, these aspects are not easily optimized, especially under time-varying network states with different quality of service (QoS) requirements. Given the importance of NFV, many approaches have been proposed to solve the VNF placement and traffic routing problem. However, those prior approaches mainly assume that the state of the network is static and known, disregarding real-time network variations. To bridge that gap, in this paper, we formulate the VNF placement and traffic routing problem as a Markov Decision Process model to capture the dynamic network state transitions. In order to jointly minimize the delay and cost of NFV providers and maximize the revenue, we devise a customized Deep Reinforcement Learning (DRL) algorithm, called A-DDPG, for VNF placement and traffic routing in a real-time network. A-DDPG uses the attention mechanism to ascertain smooth network behavior within the general framework of network utility maximization (NUM). The simulation results show that A-DDPG outperforms the state-of- the-art in terms of network utility, delay, and cost.","Network function virtualization; deep reinforcement learning; placement; routing","en","conference paper","IEEE","","","","","Accepted Author Manuscript","","","","","Embedded Systems","","",""
"uuid:a6370a52-bad4-43ac-9ff6-daa830cde6cd","http://resolver.tudelft.nl/uuid:a6370a52-bad4-43ac-9ff6-daa830cde6cd","Eliminating Speckle Noises for Laser Doppler Vibrometer Based on Empirical Wavelet Transform","Jin, J. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering)","Dvurecenskij, Andrej (editor); Manka, Jan (editor); Svehlikova, Jana (editor); Witkovsky, Viktor (editor)","2021","This paper presents a novel approach for eliminating speckle noises in Laser Doppler Vibrometer signals based on empirical wavelet transform (EWT). The moving root-mean-square thresholds are utilized to cut off signal drop-outs and produce noise discontinuity that EWT can identify. The extremum ratio behaves as the criterion to reject or accept the EWT decomposed components. While processing simulated signals, the EWT-based approach outperforms others and presents de-speckle robustness. In experiments, EWT reveals the actual vibration despite low signal-to-noise ratios, which indicates de-speckle efficiency.","Laser Doppler Vibrometer; Speckle Noise; Empirical Wavelet Transform","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.","","2021-12-07","","","Railway Engineering","","",""
"uuid:57d1e77f-17b1-435a-ab42-6b61ec581f60","http://resolver.tudelft.nl/uuid:57d1e77f-17b1-435a-ab42-6b61ec581f60","An LSTM Approach to Short-range personnel recognition using Radar Signals","Li, Zhenghui (University of Glasgow); Le Kernec, Julien (University of Glasgow); Fioranelli, F. (TU Delft Microwave Sensing, Signals & Systems); Romain, Olivier (CY Cergy Paris University); Zhang, Lei (University of Glasgow); Yang, Shufan (University of Glasgow)","","2021","In personnel recognition based on radar, significant research exists on statistical features extracted from the micro-Doppler signatures, whereas research considering other domains and information such as phase is less developed. This paper presents the use of deep learning methods to integrate both phase and magnitude features from range profiles and spectrogram. The temporal features of both domains are separately extracted using a stack of Long Short Term Memory (LSTM) layers. Then, the extracted features are aggregated in the corresponding domains and pass through a series of dense layers with SoftMax classifier. Finally, the information from the two domains is fused with a soft fusion approach to improve the performance further. Preliminary results show that the proposed network with soft fusion can achieve 85.5% accuracy in personnel recognition with six subjects","Radar sensing; Personnel Recognition; LSTM network; Phase information; Micro-Doppler signatures; Range-time information","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.","","2021-12-18","","","Microwave Sensing, Signals & Systems","","",""
"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:16e5a670-3fd0-4ce3-a35f-54ca6fc8cc1e","http://resolver.tudelft.nl/uuid:16e5a670-3fd0-4ce3-a35f-54ca6fc8cc1e","New Insights into Metric Optimization for Ranking-based Recommendation","Li, Roger Zhe (TU Delft Multimedia Computing); Urbano, Julián (TU Delft Multimedia Computing); Hanjalic, A. (TU Delft Intelligent Systems)","","2021","Direct optimization of IR metrics has often been adopted as an approach to devise and develop ranking-based recommender systems. Most methods following this approach (e.g. TFMAP, CLiMF, Top-N-Rank) aim at optimizing the same metric being used for evaluation, under the assumption that this will lead to the best performance. A number of studies of this practice bring this assumption, however, into question. In this paper, we dig deeper into this issue in order to learn more about the effects of the choice of the metric to optimize on the performance of a ranking-based recommender system. We present an extensive experimental study conducted on different datasets in both pairwise and listwise learning-to-rank (LTR) scenarios, to compare the relative merit of four popular IR metrics, namely RR, AP, nDCG and RBP, when used for optimization and assessment of recommender systems in various combinations. For the first three, we follow the practice of loss function formulation available in literature. For the fourth one, we propose novel loss functions inspired by RBP for both the pairwise and listwise scenario. Our results confirm that the best performance is indeed not necessarily achieved when optimizing the same metric being used for evaluation. In fact, we find that RBP-inspired losses perform at least as well as other metrics in a consistent way, and offer clear benefits in several cases. Interesting to see is that RBP-inspired losses, while improving the recommendation performance for all uses, may lead to an individual performance gain that is correlated with the activity level of a user in interacting with items. The more active the users, the more they benefit. Overall, our results challenge the assumption behind the current research practice of optimizing and evaluating the same metric, and point to RBP-based optimization instead as a promising alternative when learning to rank in the recommendation context.","evaluation metrics; learning to rank; recommender systems","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","Intelligent Systems","Multimedia Computing","","",""
"uuid:b4b2be9c-3e6b-4c77-ab4a-0fb0fa44531f","http://resolver.tudelft.nl/uuid:b4b2be9c-3e6b-4c77-ab4a-0fb0fa44531f","Critical Success Factors for Effective Resident Participation in Community Retrofit: A Systematic Review","Li, Y. (TU Delft Design & Construction Management); Qian, QK (TU Delft Design & Construction Management); Mlecnik, E. (TU Delft Real Estate Management); Visscher, H.J. (TU Delft Design & Construction Management)","","2021","Community residents possess first-hand knowledge of the community and effective execution of retrofit methods. Their understanding, acceptance and ultimately participation determine the smoothness of working process and the success of the project. Although the introduction of regulations and policies has increased resident participation in retrofit projects in China, the effectiveness of participation is far from guaranteed. This may be partly due to a failure to identify critical factors underlying. Thus, this paper aims to develop a set of critical success factors (CSFs) for effective resident participation in community retrofit projects. Based on the findings of the systematic review and data analysis, 29 CSFs are identified, which will influence resident participation from four dimensions: context, project, process and stakeholder. The review is presented for the reference of governments and practitioners, especially when it comes to policy making and promotion of community retrofit by improving resident participation.","community retrofit; resident participation; critical success factors","en","conference paper","ENHR","","","","","","","","","","Design & Construction Management","","",""
"uuid:f08ff56c-b43e-499d-b94b-e1c12be036e0","http://resolver.tudelft.nl/uuid:f08ff56c-b43e-499d-b94b-e1c12be036e0","An Experimental Study of Foam Trapping and Foam Mobility in a Model Fracture","Li, K. (TU Delft Reservoir Engineering); Wolf, K.H.A.A. (TU Delft Applied Geophysics and Petrophysics); Rossen, W.R. (TU Delft Reservoir Engineering)","","2021","By trapping gas, foam can improve the sweep efficiency in enhanced oil recovery. In this study, to understand gas trapping in fractures, we have conducted experiments in a model fracture with a hydraulic aperture of 80 μm. One wall of the fracture is rough, and the other wall is smooth. The fracture is made of two glass plates and the direct visualization of foam flow inside the fracture is facilitated using a high-speed camera. ImageJ has been used to perform image analysis and quantify the properties of the foam. We find that pre-generated foam has been further refined inside the model. Foam flow reaches local equilibrium, where the rate of bubble generation equals that of bubble destruction, within the model. Foam texture becomes finer and less gas is trapped as the interstitial velocity and pressure gradient increase. Shear-thinning rheology of foam has also been observed. The behavior of gas trapping in our model fracture is different from that in other geological porous media. The fraction of trapped gas is much lower (less than 7%). At the extreme, when velocity increases to 6.8 mm/s (pressure gradient to 1.8 bar/m), all the foam bubbles are flowing and there is no gas trapped inside the fracture.","Gas trapping; Foam EOR; Foam mobility; Fractures","en","conference paper","EAGE","","","","","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.","","2021-10-22","","","Reservoir Engineering","","",""
"uuid:f59b5b31-f890-4d1f-9a2f-aa77bca15333","http://resolver.tudelft.nl/uuid:f59b5b31-f890-4d1f-9a2f-aa77bca15333","An attribute-based model to retrieve storm surge disaster cases","Wang, Ke (Tsinghua University); Reniers, G.L.L.M.E. (TU Delft Safety and Security Science; Katholieke Universiteit Leuven; Universiteit Antwerpen); Yang, Yongsheng (Tsinghua University); Li, Jian (Tsinghua University); Huang, Quanyi (Tsinghua University)","Adrot, Anouck (editor); Grace, Rob (editor); Moore, Kathleen (editor); Zobel, Christopher W. (editor)","2021","In China, storm surge disasters cause severe damages in coastal regions. One of the most critical tasks is to predict affected regions and their relative damage levels to support decision-making. This study develops a two-stage retrieval model to search the most similar past disaster case to complete prediction. Based on spatial attributes of cases, the top-ranking past cases with a similar location to the target case are selected. Among these past cases, the most similar past case is selected by disaster attribute similarities. Three typical storm surge case studies have been used and implemented into this proposed model, and the results show that all the most affected regions can be predicted. The proposed model simplifies the prediction process and updates results quickly. This study provides valuable information for the government to make real-time response plans.","Affected region prediction; Multiple attributes; Retrieval model; Storm surge disaster","en","conference paper","Information Systems for Crisis Response and Management, ISCRAM","","","","","","","","","","Safety and Security Science","","",""
"uuid:3ae2d4ae-a802-40e0-bb52-0c53f81f642f","http://resolver.tudelft.nl/uuid:3ae2d4ae-a802-40e0-bb52-0c53f81f642f","Cakevr: A social virtual reality (vr) tool for co-designing cakes","Mei, Yanni (Student TU Delft); Li, Jie (Centrum Wiskunde and Informatica); de Ridder, H. (TU Delft Human Information Communication Design); Cesar, Pablo (TU Delft Multimedia Computing)","","2021","Cake customization services allow clients to collaboratively personalize cakes with pastry chefs. However, remote (e.g., email) and in-person co-design sessions are prone to miscommunication, due to natural restrictions in visualizing cake size, decoration, and celebration context. This paper presents the design, implementation, and expert evaluation of a social VR application (CakeVR) that allows a client to remotely co-design cakes with a pastry chef, through real-time realistic 3D visualizations. Drawing on expert semi-structured interviews (4 clients, 5 pastry chefs), we distill and incorporate 8 design requirements into our CakeVR prototype. We evaluate CakeVR with 10 experts (6 clients, 4 pastry chefs) using cognitive walkthroughs, and fnd that it supports ideation and decision making through intuitive size manipulation, color/favor selection, decoration design, and custom celebration theme ftting. Our fndings provide recommendations for enabling co-design in social VR and highlight CakeVR's potential to transform product design communication through remote interactive and immersive co-design.","Cake design; Co-design; Remote collaboration; Social virtual reality","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Human Information Communication Design","","",""
"uuid:b5bedf1f-eb93-46d5-a6c0-19ac382bd8df","http://resolver.tudelft.nl/uuid:b5bedf1f-eb93-46d5-a6c0-19ac382bd8df","Utilization of biomass fly ash in alkali-activated materials","Liang, X. (TU Delft Materials and Environment); Dong, H. (TU Delft Materials and Environment); Li, Z. (TU Delft Materials and Environment); van Zijl, Marc Brito (Mineralz); Ye, G. (TU Delft Materials and Environment)","Ye, Guang (editor); Dong, Hua (editor); Liu, Jiaping (editor); Schlangen, Erik (editor); Miao, Changwen (editor)","2021","This paper investigated the feasibility of using biomass fly ash (BFA) to prepare alkaliactivated slag and fly ash paste. The reference mixture was alkali-activated slag and coal fly ash (CFA) paste with a slag-to-coal fly ash ratio of 50/50. In other mixtures, coal fly ash was replaced at 40% and 100% with BFA, respectively. The results showed that the incorporation of BFA accelerated the setting of the paste, while its impact on the compressive strength was minor. XRD and FTIR results indicated that the BFA participated in the reaction process. BFA showed potential use as CFA replacement in synthesizing alkali-activated materials, which would pave a way for the valorisation of BFA.","biomass fly ash; alkali-activated materials; waste","en","conference paper","Delft University of Technology","","","","","","","","","","Materials and Environment","","",""
"uuid:3f26c2bd-cf19-499b-bda3-bc3dfa69e2e5","http://resolver.tudelft.nl/uuid:3f26c2bd-cf19-499b-bda3-bc3dfa69e2e5","Social VR: A New Medium for Remote Communication and Collaboration","Li, Jie (Centrum Wiskunde & Informatica (CWI)); Vinayagamoorthy, Vinoba (BBC Research and Development); Williamson, Julie (University of Glasgow); Shamma, David A. (Rochester Institute of Technology); Cesar, Pablo (TU Delft Multimedia Computing; Centrum Wiskunde & Informatica (CWI))","","2021","We are facing increasingly pressure on reducing travel and working remotely. Tools that support effective remote communication and collaboration are much needed. Social Virtual Reality (VR) is an emerging medium, which invites multiple users to join a collaborative virtual environment (VE) and has the potential to support remote communication in a natural and immersive way. We successfully organized a CHI 2020 Social VR workshop virtually on Mozilla Hubs, which invited researchers and practitioners to have a fruitful discussion over user representations and ethics, evaluation methods, and interaction techniques for social VR as an emerging immersive remote communication tool. In this CHI 2021 virtual workshop, we would like to organize it again on Mozilla Hubs, continuing the discussion about proxemics, social cues and VE designs, which were identified as important aspects for social VR communication in our CHI 2020 workshop.","proxemics; remote communication; social cues; Social virtual reality; virtual environment design","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Multimedia Computing","","",""
"uuid:27fb86b1-db06-449f-af0e-f9df9e34f290","http://resolver.tudelft.nl/uuid:27fb86b1-db06-449f-af0e-f9df9e34f290","The influence of the angle of attack on passenger comfort","Ping, Y. (Student TU Delft); Yao, X. (TU Delft Mechatronic Design); Xu, J. (TU Delft Mechatronic Design); Li, Juntian (External organisation); Song, Y. (TU Delft Mechatronic Design); Vink, P. (TU Delft Materials and Manufacturing)","Mansfield, Neil (editor)","2021","The angle of attack (AOA) of an airplane changes the direction of the gravitational force on passengers and thereby might influence passengers’ flying experience. However, the contribution of the AOA regarding comfort/discomfort is not fully explored. In this paper, we aim to fill this knowledge gap by identifying the relationships between the perceived comfort/ discomfort of passengers and the AOA of the plane during the take-off and climbing phases of a flight. An
experiment is conducted in a Boeing 737 fuselage where 10 participants were recruited. Each participant experiences 3 setups of seats with different AOAs (3, 14 and 18 degrees) for 20 minutes, respectively. Participants were asked to complete several sets of questionnaires during each session, and their heart rate and the pressure on the seat and the backrest were recorded as well. Experiment results indicated that participants experienced 14-degree as the most comfortable angle with the lowest discomfort, which might be useful for airlines in setting up the take-off and climbingprocedure.","Seat inclination; Comfort; Take-off/climbing","en","conference paper","","","","","","","","","","","Mechatronic Design","","",""
"uuid:3df95000-18e0-4bcd-8f35-e0acf6a7e6c5","http://resolver.tudelft.nl/uuid:3df95000-18e0-4bcd-8f35-e0acf6a7e6c5","Where to Meet a Driver Privately: Recommending Pick-Up Locations for Ride-Hailing Services","Chen, Yifei (Hefei University of Technology); Li, Meng (Hefei University of Technology); Zheng, Shuli (Hefei University of Technology); Lal, C. (TU Delft Cyber Security); Conti, M. (TU Delft Cyber Security)","Roman, Rodrigo (editor); Zhou, Jianying (editor)","2021","Ride-Hailing Service (RHS) has motivated the rise of innovative transportation services. It enables riders to hail a cab or private vehicle at the roadside by sending a ride request to the Ride-Hailing Service Provider (RHSP). Such a request collects rider’s real-time locations, which incur serious privacy concerns for riders. While there are many location privacy-preserving mechanisms in the literature, few of them consider mobility patterns or location semantics in RHS. In this work, we propose a pick-up location recommendation scheme with location indistinguishability and semantic indistinguishability for RHS. Specifically, we give formal definitions of location indistinguishability and semantic indistinguishability. We model the rider mobility as a time-dependent first-order Markov chain and generates a rider’s mobility profile. Next, it calculates the geographic similarity between riders by using the Mallows distance and classifies them into different geographic groups. To comprehend the semantics of a location, it extracts such information through user-generated content from two popular social networks and obtains the semantic representations of locations. Cosine similarity and unified hypergraph are used to compute the semantic similarities between locations. Finally, it outputs a set of recommended pick-up locations. To evaluate the performance, we build our mobility model over the real-world dataset GeoLife, analyze the computational costs of a rider, show the utility, and implement it on an Android smartphone. The experimental results show that it costs less than 0.12 ms to recommend 10 pick-up locations within 500 m of walking distance.","Android; Location privacy; Location semantics; Mobility pattern; Ride-hailing service","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.","","2022-06-30","","","Cyber Security","","",""
"uuid:42a63d75-b3c8-4c14-b9b0-e676586a86ae","http://resolver.tudelft.nl/uuid:42a63d75-b3c8-4c14-b9b0-e676586a86ae","Convex optimization-based Privacy-Preserving Distributed Least Squares via Subspace Perturbation","Li, Qiongxiu (Aalborg University); Heusdens, R. (TU Delft Signal Processing Systems; Netherlands Defence Academy); Christensen, M. Graesboll (Aalborg University)","","2020","Over the past decades, privacy-preservation has received considerable attention, not only as a consequence of regulations such as the General Data Protection Regulation in the EU, but also from the fact that people are more concerned about data abuse as the world is becoming increasingly digitized. In this paper we propose a convex optimization-based subspace perturbation approach to solve privacy-preserving distributed least squares problems. Based on the primal-dual method of multipliers, the introduced dual variables will only converge in a subspace determined by the graph topology and do not converge in its orthogonal complement. We, therefore, propose to exploit this property for privacy-preservation by using the nonconverging part of the dual variables to perturb the private data, thereby protecting it from being revealed. Moreover, we prove that the proposed approach is secure under both eavesdropping and passive adversaries. Computer simulations are conducted to demonstrate the benefits of the proposed approach through its convergence properties and accuracy.","Distributed least squares; subspace; privacy; noise perturbation; convex optimization","en","conference paper","Eurasip","","","","","","","","","","Signal Processing Systems","","",""
"uuid:ac3d9a76-59bb-4c77-ae81-f75a2813ab5d","http://resolver.tudelft.nl/uuid:ac3d9a76-59bb-4c77-ae81-f75a2813ab5d","Privacy-Preserving Distributed Graph Filtering","Li, Qiongxiu (Aalborg University); Coutino, Mario (TU Delft Signal Processing Systems); Leus, G.J.T. (TU Delft Signal Processing Systems); Christensen, M. Graesboll (Aalborg University)","","2020","With an increasingly interconnected and digitized world, distributed signal processing and graph signal processing have been proposed to process its big amount of data. However, privacy has become one of the biggest challenges holding back the widespread adoption of these tools for processing sensitive data. As a step towards a solution, we demonstrate the privacypreserving capabilities of variants of the so-called distributed graph filters. Such implementations allow each node to compute a desired linear transformation of the networked data while protecting its own private data. In particular, the proposed approach eliminates the risk of possible privacy abuse by ensuring that the private data is only available to its owner. Moreover, it preserves the distributed implementation and keeps the same communication and computational cost as its non-secure counterparts. Furthermore, we show that this computational model is secure under both passive and eavesdropping adversary models. Finally, its performance is demonstrated by numerical tests and it is shown to be a valid and competitive privacypreserving alternative to traditional distributed optimization techniques.","Distributed computation; Distributed graph filters; Encryption; Graph signal processing; Privacy-preserving","en","conference paper","Eurasip","","","","","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.","","2021-08-29","","","Signal Processing Systems","","",""
"uuid:9bf47e37-0ec8-4d77-8f7a-2e804a8e8b53","http://resolver.tudelft.nl/uuid:9bf47e37-0ec8-4d77-8f7a-2e804a8e8b53","Highly sensitive silicon Mach-Zehnder interferometer-based ultrasound sensor","Ouyang, B. (TU Delft ImPhys/Computational Imaging); Li, Yanlu (Universiteit Gent); Kruidhof, Marten (Student TU Delft); Horsten, R.C. (TU Delft ImPhys/Optics); Baets, Roel (Universiteit Gent); van Dongen, K.W.A. (TU Delft ImPhys/Medical Imaging); Caro-Schuurman, J. (TU Delft ImPhys/Computational Imaging)","Garcia-Blanco, Sonia M. (editor); Cheben, Pavel (editor)","2020","We report a highly sensitive ultrasound sensor based on an integrated photonics silicon Mach-Zehnder interferometer (MZI). One arm of the MZI is located on a thin membrane, acting as the sensing part of the device. Ultrasound waves excite the membrane's vibrational mode, thus inducing modulation of the MZI transmission. The measured sensor transfer function is centered at 0.47 MHz and has a -6 dB bandwidth of 21.2%. For 1.0 mW optical input power, we obtain a high sensitivity of 0.62 mV/Pa, a low detection limit of 0.38 mPa/Hz1/2 at the resonance frequency and a large dynamic range of 59 dB. In preliminary ultrasound imaging experiments using this sensor, an image of a wire phantom is obtained. The properties of this sensor and the generated image show that this sensor is very promising for ultrasound imaging applications.","Imaging; Integrated photonics sensors; MEMS; MZI; Ultrasound","en","conference paper","SPIE","","","","","","","","","","ImPhys/Computational Imaging","","",""
"uuid:f80f5f93-fbe0-4ddc-95c9-94583f4d1526","http://resolver.tudelft.nl/uuid:f80f5f93-fbe0-4ddc-95c9-94583f4d1526","Centrifuge benchmark testing of laterally loaded monopiles in sand","Bienen, Britta (University of Western Australia); Klinkvort, R.T. (Norwegian Geotechnical Institute); Fan, S. (University of Western Australia); Black, J. (University of Sheffield); Bayton, S. (Norwegian Geotechnical Institute); Thorel, L. (Institut Francais des Sciences et Technologies des Transports (IFSTTAR)); Madabhushi, G.S.P. (University of Cambridge); Askarinejad, A. (TU Delft Geo-engineering); Li, Q. (TU Delft Geo-engineering)","","2020","The large diameter monopile is a commonly used foundation concept for offshore wind turbines. The advantages of geometrical simplicity and reliable performance make it often the most attractive solution. Despite the concept’s high popularity, optimisation of the current design models can still be made. To address fundamental understanding of modelling effects in centrifuge testing of laterally loaded monopiles in sand, a large coordinated centrifuge-testing program across 11 different centrifuge centres worldwide is ongoing. This extended abstract presents the initial results of global benchmark testing.","Centrifuge; Monopiles; Offshore Wind turbines; Sand","en","conference paper","","","","","","","","","","","Geo-engineering","","",""
"uuid:10fca5eb-6c56-423c-a4e9-a63de59684ff","http://resolver.tudelft.nl/uuid:10fca5eb-6c56-423c-a4e9-a63de59684ff","Push for quantization: Deep fisher hashing","Li, Y. (TU Delft Pattern Recognition and Bioinformatics); Pei, W. (TU Delft Pattern Recognition and Bioinformatics; Tencent); Zha, Yufei (Northwestern Polytechnical University); van Gemert, J.C. (TU Delft Pattern Recognition and Bioinformatics)","","2020","Current massive datasets demand light-weight access for analysis. Discrete hashing methods are thus beneficial because they map high-dimensional data to compact binary codes that are efficient to store and process, while preserving semantic similarity. To optimize powerful deep learning methods for image hashing, gradient-based methods are required. Binary codes, however, are discrete and thus have no continuous derivatives. Relaxing the problem by solving it in a continuous space and then quantizing the solution is not guaranteed to yield separable binary codes. The quantization needs to be included in the optimization. In this paper we push for quantization: We optimize maximum class separability in the binary space. We introduce a margin on distances between dissimilar image pairs as measured in the binary space. In addition to pair-wise distances, we draw inspiration from Fisher's Linear Discriminant Analysis (Fisher LDA) to maximize the binary distances between classes and at the same time minimize the binary distance of images within the same class. Experiments on CIFAR-10, NUS-WIDE and ImageNet100 demonstrate compact codes comparing favorably to the current state of the art.","","en","conference paper","","","","","","","","","","","Pattern Recognition and Bioinformatics","","",""
"uuid:4c2757e0-f73e-49ff-93c0-b4d955f6eafc","http://resolver.tudelft.nl/uuid:4c2757e0-f73e-49ff-93c0-b4d955f6eafc","Convex Optimisation-Based Privacy-Preserving Distributed Average Consensus in Wireless Sensor Networks","Li, Qiongxiu (Aalborg University); Heusdens, R. (TU Delft Signal Processing Systems); Christensen, Mads Græsbøll (Aalborg University)","","2020","In many applications of wireless sensor networks, it is important that the privacy of the nodes of the network be protected. Therefore, privacy-preserving algorithms have received quite some attention recently. In this paper, we propose a novel convex optimization-based solution to the problem of privacy-preserving distributed average consensus. The proposed method is based on the primal-dual method of multipliers (PDMM), and we show that the introduced dual variables of the PDMM will only converge in a certain subspace determined by the graph topology and will not converge in the orthogonal complement. These properties are exploited to protect the private data from being revealed to others. More specifically, the proposed algorithm is proven to be secure for both passive and eavesdropping adversary models. Finally, the convergence properties and accuracy of the proposed approach are demonstrated by simulations which show that the method is superior to the state-of-the-art.","Distributed average consensus; convex optimisation; primal-dual method of multipliers; privacy; wireless sensor networks","en","conference paper","IEEE","","","","","Accepted author manuscript","","","","","Signal Processing Systems","","",""
"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:f3929bc3-7dd2-4d5e-b28a-bb49155545c4","http://resolver.tudelft.nl/uuid:f3929bc3-7dd2-4d5e-b28a-bb49155545c4","Human activity classification with radar signal processing and machine learning","Jia, Mu (University of Glasgow); Li, Shaoxuan (University of Glasgow); Le Kernec, Julien (University of Glasgow); Yang, Shufan (University of Glasgow); Fioranelli, F. (TU Delft Microwave Sensing, Signals & Systems); Romain, Olivier (University of Cergy-Pontoise)","","2020","As the number of older adults increases worldwide, new paradigms for indoor activity monitoring are required to keep people living at home independently longer. Radar-based human activity recognition has been identified as a sensing modality of choice because it is privacy-preserving and does not require end-users compliance or manipulation. In this paper, we explore the robustness of machine learning algorithms for human activity recognition using six different activities from the University of Glasgow dataset recorded with an FMCW radar. The raw radar data is pre-processed and represented using four different domains, namely, range-time, range-Doppler amplitude and phase diagrams, and Cadence Velocity Diagram. From those, salient features can be extracted and classified using Support Vector Machine, Stacked AutoEncoder, and Convolutional Neural Networks. The fusion of handcrafted features and features from CNN is applied to get the best scheme of classification with over 96% accuracy.","Radar; signal processing; Machine Learning; deep learning; classification; healthcare; assisted living","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.","","2021-03-29","","","Microwave Sensing, Signals & Systems","","",""
"uuid:56520932-a44d-4192-8728-ca74237c8bf6","http://resolver.tudelft.nl/uuid:56520932-a44d-4192-8728-ca74237c8bf6","Elderly Care: Using Deep Learning for Multi-Domain Activity Classification","Li, Shaoxuan (University of Glasgow); Jia, Mu (University of Glasgow); Le Kernec, Julien (University of Glasgow); Yang, Shufan (University of Glasgow); Fioranelli, F. (TU Delft Microwave Sensing, Signals & Systems); Romain, Olivier (University of Cergy-Pontoise)","","2020","Nowadays, health monitoring issues are increasing as the worldwide population is aging. In this paper, the radar modality is used to classify with radar signature automatically. The classic approach is to extract features from micro-Doppler signatures for classification. This data representation domain has its limitations for activities presenting similar accelerations like a frontal fall and picking up an object from the floor that lead to wrongly labeled activities. In this work, we propose to combine multiple radar data domains with deep learning. Features are extracted from four domains, namely, Range-Time, Range-Doppler, Doppler-Time, and Cadence Velocity Diagram. The extracted features are set as the input of a Convolutional Neural Network, yielding 91% accuracy with 10-fold cross-validation based on the University of Glasgow “Radar signatures of human activities” open dataset.","Machine Learning; Radar; Assisted Living; Human Activity Recognition; Multi-domain","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.","","2021-03-29","","","Microwave Sensing, Signals & Systems","","",""
"uuid:454aff8c-1367-4008-a336-929425fa9917","http://resolver.tudelft.nl/uuid:454aff8c-1367-4008-a336-929425fa9917","Parallel Framework for Complex Reservoir Simulation with AdvancedDiscretization and Linearization Schemes","Li, Longlong (Hamad Bin Khalifa University (HBKU)); Khait, M. (TU Delft Reservoir Engineering); Voskov, D.V. (TU Delft Reservoir Engineering); Abushaikha, Ahmad (Qatar Foundation; Hamad Bin Khalifa University (HBKU))","","2020","The continuous progress of reservoir monitoring technology provides encouraging capacities to reduceuncertainties in the subsurface characterization and to mitigate risks in field development applying thereservoir simulation approach. However, it is always challenging to take full advantage of the observationdata, since an accurate representation of strong heterogeneities requires a high-resolution grid. Most ofthe discretization methods cannot handle full tensor permeability, and high nonlinearity introduced bycomplex physical process drastically reduces simulation efficiency. In this work, we develop an advancedparallel framework for reservoir simulation with the implementation of state of the art discretizationand linearization methods. We apply the multipoint flux approximation (MPFA) method to handle thefull tensor permeability in unstructured grids. To keep the fidelity of the geological model and improvecomputational efficiency, we use massively parallel computations via Message Passing Interface (MPI).Complex subsurface physics is described by mass-based formulations making the framework flexible forgeneral-purpose reservoir simulation. However, the representation of phase behavior introduces additionalworkload when compared with the phase-based formulations in the traditional approach. Here, we apply theOperator-Based Linearization (OBL) approach which not only overcomes this drawback but also turns it toan advantage. In this method, the conservation equations are described in an operator form. By constructinga library of tabulated operators, the repeated work spent on complex phase behavior and property evaluationcan be significantly reduced. We benchmark the parallel framework with analytical solutions under single-phase flow and multiphase flow. The results demonstrate that the parallel framework provides accuratesimulation results for structured and unstructured grids. We validate that MPFA implemented in our parallelframework converges to real solutions when the permeability is a full tensor. Besides, several realisticcases have been rigorously tested confirming high computational capacity, efficiency, and accuracy of theadvanced massively parallel framework for general-purpose reservoir simulation. With the implementationof MPFA and OBL approaches, the parallel framework is fully equipped for the simulation of problemswith full tensor permeability, high-heterogeneities, and complex physical processes.","","en","conference paper","Society of Petroleum Engineers","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2021-06-01","","","Reservoir Engineering","","",""
"uuid:65582f95-a5b4-425e-8271-aaddfac550fb","http://resolver.tudelft.nl/uuid:65582f95-a5b4-425e-8271-aaddfac550fb","A laboratory and numerical study of transverse momentum exchange in vegetated channels","Truong, S.H. (Korea Institute of Civil Engineering and Building Technology; Thuyloi University); Li, Un (Korea Institute of Civil Engineering and Building Technology); Uijttewaal, W.S.J. (TU Delft Environmental Fluid Mechanics)","Uijttewaal, W. (editor); Franca, M.J. (editor); Valero, D. (editor); Chavarrias, V. (editor); Arbos, C.Y. (editor); Schielen, R. (editor); Crosato, A. (editor)","2020","Transverse exchange processes of mass and momentum in floodplain regions of channels are of primary importance regarding the sediment transport and riverbank stability. The presence of large horizontal coherent structures (LHCSs) at the interface of the floodplain and main channel regions may contribute up to 90% the amount of transverse momentum exchange between these areas. Although many momentum exchange models have been proposed and developed, their applicability in different circumstances is still unclear as their validity is usually restricted to a narrowly ranging experiment data set. In order to obtain more insight, two unique laboratory experiments of a shallow flow field in a floodplain channel with and without vegetation have been conducted. One small scale experiment was conducted at the TU Delft Water Lab. Another large-scale experiment of floodplain vegetated channel has been conducted at the Korea Institute of Civil Engineering and Building Technology -River Experiment Center (KICT-REC). The experimental data has been used to verify state-of-the-art momentum exchange models. As the limitations of these models were analyzed, a new eddy viscosity model based on the occurrence of LHCSs was proposed and validated using a variety of experimental data sets. A numerical model mimicking physical models was constructed. The experimental results were compared with the numerical results, showing the capacity of the new eddy viscosity model. Furthermore, the experimental results confirm the presence of LHCSs in a large-scale experiment. The LHCSs have the length of about 15m, which is one order of magnitude larger than that observed in the small-scale experiment.","Vegetated channel; experiment; large coherent structures; numerical model","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.","","2021-02-27","","","Environmental Fluid Mechanics","","",""
"uuid:aab030f5-3a1c-458f-b5da-3cf00512f75f","http://resolver.tudelft.nl/uuid:aab030f5-3a1c-458f-b5da-3cf00512f75f","A Low SWaP-C Radar Altimeter Transceiver Design for Small Satellites","Dogan, O. (TU Delft Microwave Sensing, Signals & Systems); Uysal, Faruk (TU Delft Microwave Sensing, Signals & Systems); Hoogeboom, P. (TU Delft Atmospheric Remote Sensing); Lopez Dekker, F.J. (TU Delft Mathematical Geodesy and Positioning); Li, Y. (TU Delft Mathematical Geodesy and Positioning)","Chakrabarti, Satyajit (editor); Paul, Rajashree (editor); Gill, Bob (editor); Gangopadhyay, Malay (editor); Poddar, Sanghamitra (editor)","2020","This paper discusses the design details of a high resolution, low ""Size, Weight, Power and Cost"" (SWaP-C) radar altimeter (RA) system. Operating frequency of the radar is chosen within the Ka-band to achieve the desired size and weight requirements, that are highly demanded for the small satellite missions in a cost-efficient way. We propose a system design such that, an intended radar altimeter can be built by using the Commercial off the Shelf (COTS) components. The simulation results show that the proposed RA has high potentiality for realization.","Radar design; mission concept; radar altimeter; Mission concept; Radar altimeter","en","conference paper","IEEE","","","","","Accepted author manuscript","","","","","Microwave Sensing, Signals & Systems","","",""
"uuid:ce65b1e1-de3c-484d-8bc5-4fc01a3115e7","http://resolver.tudelft.nl/uuid:ce65b1e1-de3c-484d-8bc5-4fc01a3115e7","Co-simulation of energy transition in residential sectors of Chinese lower-tier cities","van Bilsen, Daniël (Student TU Delft); Huang, Yilin (TU Delft System Engineering); Li, Fen (Shenzhen Institute of Building Research)","Bruzzone, Agostino G. (editor); Janosy, Janos Sebestyen (editor); Nicoletti, Letizia (editor); Zacharewicz, Gregory (editor)","2020","China is undergoing large changes to tackle carbon dioxide emissions and air pollution. While the top-down governance allows for clear setting of emission reduction targets for industrial sectors and major cities, reducing emissions in residential sectors in smaller (the so-called low-tier) cities remain challenging and often unaddressed. This paper studies policy options to reduce emissions in residential sectors in low-tier Chinese cities. We conducted interviews and surveys in the city of Jingmen in the Hubei province and developed simulation models with feasible policy options and realistic consumption choice preferences. The simulation provided insights to the policies on reducing household coal consumption and ensuing emissions. Our research found that top-down restrictive policies such as coal ban and coal tax are effective in reducing emissions. They, however, restrict access to affordable energy for heating and cooking, especially within rural areas. They hence need to be combined with supportive policies such as electricity subsidy to yield long-term positive impact.","Household emissions; Modelling; Residential energy consumption; Simulation","en","conference paper","","","","","","","","","","","System Engineering","","",""
"uuid:3845db1d-20c7-4a74-a547-4c2bde528b18","http://resolver.tudelft.nl/uuid:3845db1d-20c7-4a74-a547-4c2bde528b18","Embedded High-Density Trench Capacitors for Smart Catheters","Li, J. (TU Delft Electronic Components, Technology and Materials); Naaborg, Jeroen (Student TU Delft); Louwerse, Marcus (Philips Innovation Services); Henneken, Vincent (Philips Research); Eugeni, Carlo (Philips Innovation Services); Dekker, R. (TU Delft Electronic Components, Technology and Materials)","","2020","Our work presents embedded high-density oxide-nitride-oxide (ONO) trench capacitors for power supply decoupling in the next generation of smart catheters. These millimeter-scale smart catheters are using a novel integration platform, Flex-to-Rigid (F2R). In the F2R platform, various functional modules are fabricated or assembled on thin silicon islands. They are connected by flexible interconnects and can be folded into arbitrary shapes to facilitate small form-factor integration. Trench decoupling capacitors have the advantage of being integrated into the thin silicon islands of F2R to reduce the parasitic inductances and space consumption. Additionally, their small surface openings can be closed by layer deposition to enable follow-up processes on the closed-up surface. For demonstration, high aspect ratio (1.1:25 and 1.2:30) ONO trench capacitors with total areas of 300x300 µm 2 and 1000x1000 µm 2 are fabricated on planar wafers, and a 700 nm and a 1 µm thick plasma-enhanced chemical vapor deposition (PECVD) SiO2 layers are deposited to test the trench closing process. The F2R compatible ONO trench capacitors have capacitance densities of 6.17 nF/mm 2 and 10.12 nF/mm 2 , combined with breakdown voltages ranging from 28 to 30 V.","Flex-to-Rigid (F2R); HAR (High Aspect Ratio); Intravascular ultrasound (IVUS) catheter; Micro-assembly; Smart catheters; Trench Capacitors","en","conference paper","IEEE","","","","","","","","","","Electronic Components, Technology and Materials","","",""
"uuid:0ebeeb6c-e734-489b-ac32-5f8631efd251","http://resolver.tudelft.nl/uuid:0ebeeb6c-e734-489b-ac32-5f8631efd251","Designing an Integrated Wearable System for Biosensing and Self-reporting of Stress","Li, X. (TU Delft Support Human-Centered Design); Jansen, K.M.B. (TU Delft Emerging Materials); Zhang, X. (Student TU Delft); Rozendaal, M.C. (TU Delft Human Information Communication Design); Jonker, C.M. (TU Delft Interactive Intelligence)","Christer, K. (editor); Craig, C. (editor); Chamberlain, P. (editor)","2020","Stress is an important aspect of mental health which impacts on wellbeing. Wearable devices are increasingly used to help people deal with stress in daily life. However, most of the current applications focus on detecting and representing physiological data. In this paper we report on the design of an integrated wearable system composed of physiological sensors and a self-reporting interface. Through an iterative design process, we developed two prototypes and evaluated their technical performance in a laboratory condition. We elaborate on the issues we have encountered and addressed in the design iterations. We discuss how these lessons might contribute to the design of integrated sensing systems in real life. We end this paper by reviewing limitations of the study and directions for future work.Keywords: smart wearables, stress management, design for mental health","Smart wearables; Stress management; design for mental healh","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.","","2021-02-01","","","Support Human-Centered Design","","",""
"uuid:48b377b7-f88f-450e-8c96-ae0d67b49ca7","http://resolver.tudelft.nl/uuid:48b377b7-f88f-450e-8c96-ae0d67b49ca7","Distributed Radar Information Fusion for Gait Recognition and Fall Detection","Li, Haobo (University of Glasgow); Le Kernec, Julien (University of Glasgow); Mehul, Ajay (University of Alabama); Fioranelli, F. (TU Delft Microwave Sensing, Signals & Systems)","","2020","This paper discusses a fusion framework with data from multiple, distributed radar sensors based on conventional classifiers, and transfer learning with pre-trained deep networks. The application considered is the classification of gait styles and the detection of critical accidents such as falls. The data were collected from a network comprised of one Ancortek frequency modulated continuous wave radar and three ultra wide-band Xethru radars. The radar systems within the network were placed in three different locations, notably, in front of participants, on the ceiling, and on the right-hand side of the monitored area. The proposed information fusion framework compares feature level fusion, soft fusion with the classifier confidence level, and hard fusion with Naïve Bayes combiner (NBC). Regarding the classifier, linear SVM, Random-Forest Bagging Trees, and five pre-trained neural networks are introduced to the fusion algorithm, where the VGG-16 network yields the best performance (about 84%) with the help of NBC. Compared to the best cases with conventional classifiers, it is reported that 20% and 16% subsequent improvement are achieved for individual usage of single radar and fusion","information fusion; machine learning; multiple radar sensing; radar network; transfer 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.","","2021-06-04","","","Microwave Sensing, Signals & Systems","","",""
"uuid:2db10787-ffa9-4744-9163-219ffb12e569","http://resolver.tudelft.nl/uuid:2db10787-ffa9-4744-9163-219ffb12e569","Dynamic Graph Filters Networks: A Gray-box Model for Multistep Traffic Forecasting","Li, G. (TU Delft Transport and Planning); Knoop, V.L. (TU Delft Transport and Planning); van Lint, J.W.C. (TU Delft Transport and Planning)","","2020","Short-term traffic forecasting is one of the key functions in Intelligent Transportation System (ITS). Recently, deep learning is drawing more attention in this field. However, how to develop a deep learning based traffic forecasting model that can dynamically extract explainable spatial correlations from traffic data is still a challenging issue. The difficulty mainly comes from the inconsistency between static model structures and the dynamic evolution of traffic conditions. To overcome this difficulty, we proposed a novel multistep speed forecasting model, Dynamic Graph Filters Networks (DGFN). The major contribution is that the regular pixel-wise dynamic convolution is extended to graph topology. DGFN has a simple recurrent cell structure where local area-wide graph convolutional kernels are dynamically computed from varying inputs. Experiments on ring freeways show that DGFN is able to precisely predict short-term evolution of traffic speed. Furthermore, we theoretically explain why DGFN is not a pure “black-box”, but a “gray-box” model that actually reduces entangled spatial and temporal features into one component representing dynamic spatial correlations. It permits tracking real-time interactions among adjacent links. DGFN has the potential to relate trained parameters in deep learning models with physical traffic variables.","","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.","","2021-06-24","","","Transport and Planning","","",""
"uuid:e6be2bc2-7e9f-4c31-b73f-5eabed41b5c7","http://resolver.tudelft.nl/uuid:e6be2bc2-7e9f-4c31-b73f-5eabed41b5c7","An Experimental Study of the Effect of Gravity on Foam in Fractures","Li, K. (TU Delft Reservoir Engineering); Wolf, K.H.A.A. (TU Delft Applied Geophysics and Petrophysics); Rossen, W.R. (TU Delft Reservoir Engineering)","","2020","In this study, to investigate how gravity affects foam in fractures, we carry out seven sets of foam-scan experiments on three glass model fractures (model A, model B and model C) with a hydraulic aperture of 78, 98 and 128 microns respectively. We compare the behaviour of foam in the models placed horizontally and vertically. We find that stable foam is created and reaches local equilibrium in all horizontal-flow experiments in 3 models. Foam gets weaker as the hydraulic aperture of fracture becomes larger. In sideways flow experiments, the effect of gravity on foam stability is less in model A. As the hydraulic aperture increases, the effect of gravity is more pronounced. Due to gravity, drier and coarser foam propagates at the top of the fractures, wetter and finer foam along the bottom. Foam is stable during the sideways flow experiments in model A and B, at all foam qualities. In model C, foam breakage alternates with re-generation near the top at foam qualities larger than 0.94. It is concluded that the application of foam in vertical natural fractures (meters tall and tens of meter long) with an aperture up to hundreds of microns is problematic.","","en","conference paper","EAGE","","","","","Accepted Author Manuscript","","2021-02-01","","","Reservoir Engineering","","",""
"uuid:a149a2e6-a7db-49e5-943b-f9660ff94018","http://resolver.tudelft.nl/uuid:a149a2e6-a7db-49e5-943b-f9660ff94018","Analysing usability and presence of a virtual reality operating room (VOR) simulator during laparoscopic surgery training","Li, M. (TU Delft Applied Ergonomics and Design; Xi’an Jiaotong University); Ganni, S. (TU Delft Applied Ergonomics and Design; GSL Medical College); Ponten, Jeroen (Catharina Hospital); Albayrak, A. (TU Delft Applied Ergonomics and Design); Rutkowski, Anne-F (Tilburg University); Jakimowicz, J.J. (TU Delft Applied Ergonomics and Design; Catharina Hospital)","","2020","Immersive Virtual Reality (VR) laparoscopy simulation is emerging to enhance the attractiveness and realism of surgical procedural training. This study analyses the usability and presence of a Virtual Operating Room (VOR) setup via user evaluation and sets out the key elements for an immersive environment during a laparoscopic procedural training.In the VOR setup, a VR headset displayed a 360-degree computer-generated Operating Room (OR) around a VR laparoscopic simulator during laparoscopy procedures. Thirty-seven surgeons and surgical trainees performed the complete cholecystectomy task in the VOR. Questionnaires (i.e., Localized Postural Discomfort scale, Questionnaire for Intuitive Use, NASA-Task Load Index, and Presence Questionnaire) followed by a semi-structured interview were used to collect the data.The participants could intuitively adapt to the VOR and were satisfied when performing their tasks (M=3.90, IQR=0.70). The participants, particularly surgical trainees, were highly engaged to accomplish the task. Despite the higher mental workload on four subscales (p < 0.05), the surgical trainees had a lower effort of learning (4 vs 3.33, p < 0.05) compared to surgeons. The participants experienced very slight discomfort in seven body segments (0.59-1.16). In addition, they expected improvements for team interaction and personalized experience within the setup.The VOR showed potential to become a useful tool in providing immersive training during laparoscopy procedure simulation based on the usability and presence noted in the study. Future developments of user interfaces, VOR environment, team interaction and personalization should result in improvements of the system.","Human computer interaction; Human-centered computing; Human-centered computing [Virtual Reality]; Laparoscopy simulation; Life and medical science; Presence; Surgical training; Usability; User evaluation; Virtual reality operating room; [Applied Computing]","en","conference paper","IEEE","","","","","","","","","","Applied Ergonomics and Design","","",""
"uuid:0ca4fb20-6561-4372-8410-5752772320d2","http://resolver.tudelft.nl/uuid:0ca4fb20-6561-4372-8410-5752772320d2","Thin-Film Lithium Niobate Acoustic Delay Line Oscillators","Li, Ming Huang (University of Illinois at Urbana-Champaign; National Tsing Hua University); Lu, Ruochen (University of Illinois at Urbana-Champaign); Manzaneque Garcia, T. (TU Delft Dynamics of Micro and Nano Systems); Gong, Songbin (University of Illinois at Urbana-Champaign)","Cheung, Karen (editor); Horsley, David (editor)","2020","In this work, thin-film lithium niobate (LiNbO3) acoustic delay line (ADL) based oscillators are experimentally investigated for the first time for the application of single-mode oscillators and frequency comb generation. The design space for the ADL-based oscillator is first analyzed, illustrating that the key to low phase noise lies in high center frequency (fo), large delay (τ G), and low insertion loss (IL) of the delay. Therefore, two self-sustained oscillators employing low noise amplifiers (LNA) and a low IL, long delay (fo=157MHz, IL =2.9dB, τG= 200-440ns) SH0 mode ADLs are designed for a case study. The two SH0 ADL oscillators show measured phase noise of -109 dBc/Hz and -127 dBc/Hz at 10-kHz offset while consuming 16 mA and 48 mA supply currents, respectively. Although the carrier power of the proposed oscillator is lower than published state-of-the-art ADL oscillators, competitive phase noise performance is still attained thanks to the low IL. Finally, frequency comb generation is also demonstrated with the same delay line and a commercial RF feedback amplifier, showing a comb spacing of 3.4 MHz that matches the open-loop characterization.","acoustic delay lines; lithium niobate; MEMS; oscillator; phase noise; piezoelectric transducers","en","conference paper","IEEE","","","","","Accepted Author Manuscript","","","","","Dynamics of Micro and Nano Systems","","",""
"uuid:a596b4ac-a770-4f84-a018-173d83b84155","http://resolver.tudelft.nl/uuid:a596b4ac-a770-4f84-a018-173d83b84155","Segmented energy tariff design for flattening load demand profile","Li, N.L. (TU Delft Energie and Industrie); Hakvoort, R.A. (TU Delft Energie and Industrie); Lukszo, Z. (TU Delft Energie and Industrie)","","2020","In this paper, a segmented energy tariff design is proposed to incentivize consumers to flatten load demand. This energy tariff focuses on consumption levels instead of consumption periods. Energy storage is an effective strategy to help to maintain the imported energy from grid below the threshold without affecting the comfort of energy consuming. From economic perspective, both battery size and segmented energy prices should be considered to minimize the total energy cost. For the considered home battery system, when the threshold value and battery size is larger than 0.45 kWh and 3 kWh respectively, the imported energy from grid is zero. When the price ratio is larger than 9, it is beneficial for consumers to response to load flattening with battery to reduce energy cost. It is recommended that policy makers or electricity regulators take the tariff incentive into account to make it attractive for consumers to respond to load flattening.","Energy cost; Load flattening; Price ratio; Segmented energy tariff","en","conference paper","IEEE","","","","","","","","","","Energie and Industrie","","",""
"uuid:8b603af9-6e22-4be7-9919-fccbb9cfcc00","http://resolver.tudelft.nl/uuid:8b603af9-6e22-4be7-9919-fccbb9cfcc00","A Science Mapping Review of Human and Organizational Factors in Structural Reliability","Ren, X. (TU Delft Safety and Security Science); Terwel, K.C. (TU Delft Applied Mechanics); Li, Jie (Shanghai Maritime University); van Gelder, P.H.A.J.M. (TU Delft Safety and Security Science)","Baraldi, Piero (editor); Di Maio, Francesco (editor); Zio, Enrico (editor)","2020","In the structural safety field, it is widely acknowledged that human error is the major contributor to structural failure. Since Human and Organizational Factors (HOFs) are critical latent conditions that can lead to human errors and further structural failures, it is essential to study into HOFs in the building industry to prevent the occurrence of failures. In this research, a bibliometric review of the existing literature on HOFs influencing structural reliability was conducted and results have been visualized in science maps. Insights into the publication output and trend, the key topics and its evolvement over time, the publication sources, as well as the contributing academics and their collaborations have been gained from the science mapping review. Apart from this, HOFs were collected from literature, after which a meta-analysis has been performed to identify the critical factors for structural reliability. In conclusion, this review provides a holistic picture of the current status for studies concerning HOFs influencing structural reliability and outlines the possible critical HOFs identified by existing research.","Human and organizational factors; Structural reliability; Literature review; Science mapping; Human error; Meta-analysis","en","conference paper","RSP Research Publishing","","","","","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.","","2022-02-02","","","Safety and Security Science","","",""
"uuid:e93d8f89-df2d-41f7-a7ce-d41cd67b54ef","http://resolver.tudelft.nl/uuid:e93d8f89-df2d-41f7-a7ce-d41cd67b54ef","A Novel Method for Railway Crossing Monitoring Based on Ambient Vibration Caused by Train-Track Interaction","Shen, C. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering); Dollevoet, R.P.B.J. (TU Delft Railway Engineering)","Klomp, Matthijs (editor); Bruzelius, Fredrik (editor); Nielsen, Jens (editor); Hillemyr, Angela (editor)","2020","Railway crossings are critical components in the rail network. They usually degrade faster than the other components. It is therefore vital to monitor their conditions using appropriate methods. This paper proposes to use the ambient vibration caused by the train-track interaction from a distance to monitor the condition of railway crossings. Both impact tests and pass-by measurements were performed on an instrumented crossing. The eigenfrequencies and mode shapes in the frequency range of 10–2000 Hz are first identified by impact tests using three different devices, i.e. a falling weight device, a big hammer and a small hammer. For the pass-by measurement, the dynamic features of both the wheel-crossing impact and ambient vibration are analyzed using time-frequency representations. It is shown that the ambient vibration signals are stationary and contain several characteristic frequencies. Then a method based on the frequency domain decomposition is applied to the ambient vibration signals to further identify the frequency components. It is found that the frequencies identified from the pass-by measurement agree well with the eigenfrequencies identified from the impact test. The proposed method can be further developed to continuously monitor the condition of railway crossings without interrupting train operations.","Ambient vibrations; Condition monitoring; Pass-by measurement; Railway crossing","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.","","2020-08-13","","","Railway Engineering","","",""
"uuid:b319c249-4a55-4775-8fe3-d259a2c94887","http://resolver.tudelft.nl/uuid:b319c249-4a55-4775-8fe3-d259a2c94887","Comparison of Data-driven Prognostics Models: A Process Perspective","Li, R. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","Beer, Michael (editor); Zio, Enrico (editor)","2019","Remaining useful life (RUL) prediction is crucial for the implementation of Prognostics and Health Management (PHM) systems, enabling application of predictive maintenance strategies for critical systems (e.g. in aviation, power, railway). Existing literature addresses aspects of data-driven prognostic approaches, with a predominant focus on introducing and testing various novel prediction techniques which are purposed towards improving prediction accuracy performance. However, a relative lack of research can be identified when considering a comparative evaluation of competing for data-driven approaches. In particular, the contributing process elements and characteristics of data-driven prognostics methods are typically not compared in detail. To overcome these drawbacks, this paper aims to evaluate the underlying technical processes for statistical and artificial neural networks (ANN) methods for prognostics. A case study is conducted to implement both approaches on the PHM08 Challenge Data Set for comparison. This research comprehensively compares the statistical and ANN prognostic methods in a systematic manner, covering and comparing their respective technical processes, and evaluates the results with respect to prediction accuracy","Remaining useful life (RUL); Prognostics and Health Management (PHM); Data-Driven Prognostics; Statistical Prognostic; Artificial Neural Network (ANN)","en","conference paper","Research Publishing","","","","","","","","","","Air Transport & Operations","","",""
"uuid:deb31335-a351-4a90-8a44-5205c7121147","http://resolver.tudelft.nl/uuid:deb31335-a351-4a90-8a44-5205c7121147","From the lab to the OB truck: Object-based broadcasting at the FA Cup in Wembley Stadium","RÖggla, Thomas (Centrum Wiskunde & Informatica (CWI)); Li, Jie (Centrum Wiskunde & Informatica (CWI)); Fjellsten, Stefan (ChyronHego AB, Stockholm); Jansen, Jack (Centrum Wiskunde & Informatica (CWI)); Kegel, Ian (BT Applied Research, Ipswich); Pilgrim, Luke (BT Applied Research, Ipswich); Trimby, Martin (BT Applied Research, Ipswich); Williams, Doug (BT Applied Research, Ipswich); Cesar, Pablo (TU Delft Multimedia Computing; Centrum Wiskunde & Informatica (CWI))","Brewster, Stephen (editor); Fitzpatrick, Geraldine (editor)","2019","While traditional live-broadcasting is typically comprised of a handful of well-defined workflows, these become insufficient when targeting multiple screens and interactive companion devices on the viewer side. In this case study, we describe the development of an end-to-end system enabling immersive and interactive experiences using an object-based broadcasting approach. We detail the deployment of this system during the live broadcast of the FA Cup Final at Wembley Stadium in London in May 2018. We also describe the trials and interviews we ran in the run-up to this event, the infrastructure we used, the final software developed for controlling and rendering on-screen graphics and the system for generating and configuring the live broadcast-objects. In this process, we learned about the workflows inside an OB truck during live productions through an ethnographic study and the challenges involved in running an object-based broadcast over the Internet, which we discuss alongside other gained insights.","Field study; Immersive experiences; Networking; Object-based broadcasting; Second screens; User interface design","en","conference paper","Association for Computing Machinery (ACM)","","","","","","","","","","Multimedia Computing","","",""
"uuid:9384de41-6dbd-4836-8815-a73b8d595dcf","http://resolver.tudelft.nl/uuid:9384de41-6dbd-4836-8815-a73b8d595dcf","Finding Membrane Shells Subjected to Horizontal Body Forces with Radial Basis Functions","Chiang, Y.-C. (TU Delft Structural Design & Mechanics); Borgart, A. (TU Delft Structural Design & Mechanics); Li, Q. (Nanjing University)","Lázaro, Carlos (editor); Bletzinger, Kai-Uwe (editor); Oñate, Eugenio (editor)","2019","Membrane shells, which have minimized bending moments under certain load conditions, are regarded as ideal structural forms in terms of material efficiency. Most of the existing numerical form-finding methods are based on discretizing membranes into finite panels or funicular networks and focusing on gravitational loading only. In order to obtain smooth shells and to consider horizontal loads, this paper presents a method to find the equilibrium forms of the membrane shells by solving Pucher’s equation. Radial base functions (RBFs) is utilized to represent stresses and shapes of the membranes, and a least square method is applied to find the controlling coefficients which allow the functions to fit the boundary conditions (e.g. zero stresses at the free edges) and the governing equation. When all the parameters are carefully chosen, the stress and shape functions can achieve sufficient accuracy. The presented method has been preliminarily implemented to find shells on a triangle ground plan incorporating horizontal loads. The form-found geometries are then analyzed by finite element models. The result confirms that the form-found shells have the stress distributions similar to the prescribed stresses.","concrete viaducts; conceptual design; parametric design; associative design; knowledge model; BIM","en","conference paper","CIMNE","","","","","","","","","","Structural Design & Mechanics","","",""
"uuid:6f93ffa9-489a-4052-9fee-09c34a2f2d95","http://resolver.tudelft.nl/uuid:6f93ffa9-489a-4052-9fee-09c34a2f2d95","An analytical approach for predicting the collapse pressure of the flexible risers withinitial ovalization and gap","Li, X. (TU Delft Marine and Transport Technology); Jiang, X. (TU Delft Transport Engineering and Logistics); Hopman, J.J. (TU Delft Marine and Transport Technology; TU Delft Ship Design, Production and Operations)","","2019","A flexible riser is a flexible pipe that transports materials between seafloor and topside structures. As oil and gas production heads to water depths greater than 3000 meters, huge hydrostatic pressure may cause the collapse failure of flexible risers. Generally, the collapse strength of a flexible riser is designed by considering the effects of initial imperfections, e.g., ovality of the carcass, and radial gap between the carcass/liner and pressure armor. These two imperfections may cause a significant reduction in the collapse strength of flexible risers under the flooded annulus condition. However, there are few analytical models available in the public literature that could take those factors into account. In this paper, an analytical approach is presented to predict the critical collapse pressure of the flexible risers with initial imperfections. The analytical results were compared with the numerical simulation, which showed reasonably good agreement.","collapse strength; flexible risers; initial ovality; radial gap","en","conference paper","ASME","","","","","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.","","2020-05-11","","Marine and Transport Technology","Transport Engineering and Logistics","","",""
"uuid:d7056512-7fa9-407b-8294-f410760f6725","http://resolver.tudelft.nl/uuid:d7056512-7fa9-407b-8294-f410760f6725","Isothermal calorimetric study on the heat evolution and the apparent activation energy of alkali-activated slag/fly ash pastes","Zhang, Shizhe (TU Delft Materials and Environment); Zuo, Y. (TU Delft Materials and Environment); Li, Z. (TU Delft Materials and Environment); Ye, G. (TU Delft Materials and Environment)","","2019","Alkali-activated slag/fly ash (AASF) as an environmental-friendly binder system for construction materials has recently attracted great attention from both academic and industrial communities. Towards its wider engineering application, it is crucial to have a better understanding of the temperature induced effects by different curing regimes and the temperature sensitivity on the thermal properties of this system, for instance the apparent activation energy (Ea). However, the available information on Ea of AASF system is still quite limited.
The present study is aimed at investigating the role of alkaline activator chemistry on the reaction kinetics of AASF at early age. The binder is made of 50 wt.% blast furnace slag and 50 wt.% fly ash. Four alkaline activator silicate moduli (SiO2/Na2O ratio = 0.8, 1.0, 1.2 and 1.5) were used for the mixture preparation. The effect of activator modulus on the heat evolution was studied by performing isothermal calorimetry test up to 160 h at both 20°C and 40 °C. The cumulative heat release and ultimate total heat were studied through curve fitting using exponential model. Furthermore, the Ea of AASF pastes was determined using incremental methods and its variation over wide range of early age reaction was studied. It was found that the activator modulus evidently influences the heat evolution of AASF. The cumulative heat release reached the maximum value at activator modulus of 1.0, followed by at 0.8, 1.2 and 1.5. This trend is inversely related to the changes of Ea of AASF mixtures. In addition, it was confirmed that the Ea of AASF was not only related to the chemistry of reactants but also reaction-stage dependent. Particularly it varied significantly at the very early age of reaction.
28 Si epitaxial module ecosystem for growing isotopically pure substrates with among the best Hall mobility at these oxide thicknesses, (ii) a custom 300mm qubit testchip and integration/device line, and (iii) a novel dual nested gate integration process for creating quantum dots.","","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.","","2019-07-16","","TU Delft Services","QCD/Vandersypen Lab","","",""
"uuid:e4775897-8cb2-4253-8532-2dc36079f31b","http://resolver.tudelft.nl/uuid:e4775897-8cb2-4253-8532-2dc36079f31b","PRF Sampling Strategies for SwarmSAR Systems","Iannini, L. (TU Delft Optical and Laser Remote Sensing); Mancinelli, A. (TU Delft Microwave Sensing, Signals & Systems); Lopez Dekker, F.J. (TU Delft Mathematical Geodesy and Positioning); Hoogeboom, P. (TU Delft Atmospheric Remote Sensing); Li, Y. (TU Delft Mathematical Geodesy and Positioning); Uysal, Faruk (TU Delft Microwave Sensing, Signals & Systems); Yarovoy, Alexander (TU Delft Microwave Sensing, Signals & Systems)","","2019","The work investigates staggered and random PRF (Pulse Repetition Frequency) strategies for a close formation of small Synthetic Aperture Radar (SAR) satellites operating in a multistatic configuration. The satellites are positioned within a fraction of the along-track critical baseline, hence allowing for the application of Displaced Phase Center image formation approaches. The performance of regular and random pulse sampling schemes is in particular assessed for a single-input multiple-output (SIMO) S-Band constellation, whose feasibility is further analyzed in relation to the number of satellites and their antenna size.","Multi-static geometry; S-Band; SAR system design; pulse repetition frequency; staggered PRF","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.","","2021-12-03","","","Optical and Laser Remote Sensing","","",""
"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:e980b01f-0f92-4d72-ac68-e55302407f77","http://resolver.tudelft.nl/uuid:e980b01f-0f92-4d72-ac68-e55302407f77","Studying a new embarking and disembarking process for future hyperloop passengers","Li, Danxue (Student TU Delft); van der Vegte, Wilhelm Frederik (TU Delft Cyber-Physical Systems); Geuze, Mars (Hardt Hyperloop); van der Meijs, Marinus (Hardt Hyperloop); Hiemstra-van Mastrigt, S. (TU Delft Mechatronic Design)","Bagnara, S. (editor); Tartaglia, R. (editor); Albolino, S. (editor); Alexander, T. (editor); Fujita, Y. (editor)","2019","This paper presents an embarking and disembarking process for the hyperloop, a future high-speed transportation of passengers and goods in tubes. A concept of the (dis)embarking process has been designed and tested with two experiments. The first experiment was performed to compare the new concept to one that is more similar to the current embarking setup of trains on the aspects of efficiency and experience. Participants were asked to (dis)embark in the test settings that simulate the new concept and the conventional situation with luggage. As a result, new passenger flow saves 40% of the time for vehicles to stay on the platform. Follow-up questionnaires and interviews with the participants show that the proposed passenger flow gives a better experience in terms of efficiency, seamlessness and friendliness. The new solution increases the number of doors, which increases the manufacturing complexity and the chance of failure. Narrowing the door size minimizes this effect. Subsequently, a second experiment has been carried out to study the influence of door width on (dis)embarking efficiency and passenger experience following a similar method. It turns out that narrowing the door width does not noticeably influence the embarking time, but the disembarking time does increase. Interviews show that half of the participants sense a negative experience with narrower doors, while the other half do not notice a difference.","Boarding; Luggage solution; Passenger flow","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","","2019-02-05","","","Cyber-Physical Systems","","",""
"uuid:70fcb01e-7e6a-4748-8f24-d5760e60d29f","http://resolver.tudelft.nl/uuid:70fcb01e-7e6a-4748-8f24-d5760e60d29f","Cumulative learning","Thórisson, Kristinn R. (Reykjavik University); Bieger, J.E. (TU Delft Information and Communication Technology; Reykjavik University); Li, X. (Temple University); Wang, Pei (Temple University)","Hammer, Patrick (editor); Agrawal, Pulin (editor); Goertzel, Ben (editor); Iklé, Matthew (editor)","2019","An important feature of human learning is the ability to continuously accept new information and unify it with existing knowledge, a process that proceeds largely automatically and without catastrophic side-effects. A generally intelligent machine (AGI) should be able to learn a wide range of tasks in a variety of environments. Knowledge acquisition in partially-known and dynamic task-environments cannot happen all-at-once, and AGI-aspiring systems must thus be capable of cumulative learning: efficiently making use of existing knowledge while learning new things, increasing the scope of ability and knowledge incrementally—without catastrophic forgetting or damaging existing skills. Many aspects of such learning have been addressed in artificial intelligence (AI) research, but relatively few examples of cumulative learning have been demonstrated to date and no generally accepted explicit definition exists of this category of learning. Here we provide a general definition of cumulative learning and describe how it relates to other concepts frequently used in the AI literature.","Artificial general intelligence; Autonomous knowledge acquisition; Cumulative learning; Knowledge representation","en","conference paper","Springer","","","","","","","","","","Information and Communication Technology","","",""
"uuid:01057dec-59bb-4a8f-9adb-8e594674afca","http://resolver.tudelft.nl/uuid:01057dec-59bb-4a8f-9adb-8e594674afca","Comparison of Questionnaire Based and User Model Based Usability Evaluation Methods","Li, M. (TU Delft Applied Ergonomics and Design; Xi’an Jiaotong University); Albayrak, A. (TU Delft Applied Ergonomics and Design); Zhang, Yu (Xi’an Jiaotong University); van Eijk, D.J. (TU Delft Applied Ergonomics and Design); Yang, Zengyao (Xi’an Jiaotong University)","Bagnara, Sebastiano (editor); Tartaglia, Riccardo (editor); Albolino, Sara (editor); Alexander, Thomas (editor); Fujita, Yushi (editor)","2019","The usability now serves as a fundamental quality of a computational device, e.g. smartphone. Moreover, the smartphone has firmly embedded into our daily life as an indispensable part, so the context and style that user may interact with them are largely different from a decade ago. Nowadays, testing usability with end user has become a common sense. Thus, how valid a usability evaluation method could assess the ‘extent to which a product can be used by specified users’ (ISO 9241-11) to facilitate software design becomes an interesting question to explore. In this research, three usability evaluation methods are compared. Among these methods, IsoMetrics is a standard questionnaire aiming at offer usability data for summative and formative evaluation; SUMI aims to assess quality of software product from end users perspective; User Model Checklist is a method based on user’s cognition-motor chain in specific tasks. The coverage and amount of usability issues, user’s effort of evaluation and software developer’s feedback on evaluation result are compared under a simulated usability test on SMS function with a smartphone. The result indicate that User Model Checklist could cover 90.4% of the usability issues found by IsoMetrics and SUMI, while 26.3% usability issues found by User Model Checklist could not be covered by IsoMetrics and SUMI. Users put highest effort on accomplish IsoMetrics and lowest effort on User Model Checklist. Moreover, the feedbacks from the developers show that the User Model Checklist requires lower usability knowledge, offers clearer improvement points and supports detailed design better.","IsoMetrics; SUMI; Usability evaluation comparison; User Model Checklist","en","conference paper","Springer","","","","","Accepted author manuscript","","2020-08-12","","","Applied Ergonomics and Design","","",""
"uuid:e790615d-3a7f-4f16-8864-c811e1100eaf","http://resolver.tudelft.nl/uuid:e790615d-3a7f-4f16-8864-c811e1100eaf","Hand-tremor frequency estimation in videos","Pintea, S. (TU Delft Pattern Recognition and Bioinformatics); Zheng, Jian (Student TU Delft); Li, Xilin (Student TU Delft); Bank, Paulina J.M. (Leiden University Medical Center); van Hilten, Jacobus J. (Leiden University Medical Center); van Gemert, J.C. (TU Delft Pattern Recognition and Bioinformatics)","Leal-Taixé, Laura (editor); Roth, Stefan (editor)","2019","We focus on the problem of estimating human hand-tremor frequency from input RGB video data. Estimating tremors from video is important for non-invasive monitoring, analyzing and diagnosing patients suffering from motor-disorders such as Parkinson’s disease. We consider two approaches for hand-tremor frequency estimation: (a) a Lagrangian approach where we detect the hand at every frame in the video, and estimate the tremor frequency along the trajectory; and (b) an Eulerian approach where we first localize the hand, we subsequently remove the large motion along the movement trajectory of the hand, and we use the video information over time encoded as intensity values or phase information to estimate the tremor frequency. We estimate hand tremors on a new human tremor dataset, TIM-Tremor, containing static tasks as well as a multitude of more dynamic tasks, involving larger motion of the hands. The dataset has 55 tremor patient recordings together with: associated ground truth accelerometer data from the most affected hand, RGB video data, and aligned depth data.","Eulerian hand tremors; Human tremor dataset; Phase-based tremor frequency detection; Video hand-tremor analysis","en","conference paper","Springer","","","","","","","","","","Pattern Recognition and Bioinformatics","","",""
"uuid:513df99b-b812-4d7b-a646-4d3fa4d29eed","http://resolver.tudelft.nl/uuid:513df99b-b812-4d7b-a646-4d3fa4d29eed","Effect of scour on the behavior of a combined loaded monopile in sand","Li, Q. (TU Delft Geo-engineering); Prendergast, L.J. (TU Delft Geo-engineering); Askarinejad, A. (TU Delft Geo-engineering); Gavin, Kenneth (TU Delft Geo-engineering)","","2018","Pile foundations used for offshore wind structures are subjected to large lateral loading from wind and waves while in service as well as significant vertical loading from the top structure. Erosion of soil from around these structures, termed scour, poses a significant problem for the structural stability. In order to better understand the performance of piles facing scour problems, the effect of local scour on the behavior of mono-piles installed in sand under combined lateral and vertical loading has been investigated using the Finite Element Method (FEM) using PLAXIS in this paper. The simulation results showed that vertical loading can decrease pile lateral displacement and improve the lateral capacity of piles in the absence of scour and under scour. The increase of scour depth will largely reduce lateral capacity of piles.","","en","conference paper","","","","","","","","","","","Geo-engineering","","",""
"uuid:501de6b4-38a4-43fd-9e92-dd82ee464748","http://resolver.tudelft.nl/uuid:501de6b4-38a4-43fd-9e92-dd82ee464748","Smart technology solutions for the NeTIRail-INFRA case study lines: Axle box acceleration and ultra-low cost smartphones","Nunez, Alfredo (TU Delft Railway Engineering); Popa, Tudor (ADS Electronics); Anghel, Lucian Emmanuel (ADS Electronics); Hendriks, J.M. (TU Delft Railway Engineering); Moraal, J. (TU Delft Railway Engineering); Buretea, Laurentiu Dorin (ADS Electronics); Paragreen, Jon (University of Sheffield); Miron, Berbece (RC‐CF); Gheorghe, Draghici (RC‐CF); Campean, Mihail (RC‐CF); Dollevoet, R.P.B.J. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering)","","2018","In this paper, we present preliminary results on the development of smart technology solutions for lower density railway lines. The goal is to reach a cost effective inspection and asset management to minimize maintenance
interventions time/cost without dedicated inspection vehicles. The proposed methods include axle box acceleration measurements and ultra-low cost smartphones. The collected data will be further used to increase knowledge of the condition of the railway track and to estimate the comfort of passengers. In order to make use of the data, the data is interpreted and converted from monitoring information into management information. Feasibility and preliminary studies were conducted in the railway lines of Romania. The results presented in this paper were obtained in the framework of the H2020 project NeTIRail-INFRA, Work Package 4: Monitoring and Smart Technology.","Railway technology; axle box acceleration measurements; ultra-low cost smartphones; railway track quality; train ride comfort; H2020 project","en","conference paper","","","","","","","","","","","Railway Engineering","","",""
"uuid:d345c4b5-9925-4e67-ac1a-effec28763a6","http://resolver.tudelft.nl/uuid:d345c4b5-9925-4e67-ac1a-effec28763a6","Experimental Study of the Chemical Deformation of Metakaolin Based Geopolymer","Li, Z. (TU Delft Materials and Environment); Ye, G. (TU Delft Materials and Environment)","","2018","Chemical deformation is an important material property which influences the autogenous deformation of the materials. While geopolymer is emerging as an eco-friendly alternative to ordinary Portland cement (OPC), few studies have been conducted on the chemical deformation of this material. In this paper, the chemical deformation of a metakaolin (MK) based geopolymer is studied. Unlike OPC paste which exhibits monotonous chemical shrinkage, metakaolin-based geopolymers can show chemical shrinkage and chemical expansion at different stages of curing. X-ray diffraction (XRD) and Fourier transform Infrared Spectrophotometer (FTIR) tests were conducted to characterize the geopolymer paste cured at different ages in order to explain the mechanisms of different chemical deformation behaviors. It was confirmed that the early age chemical shrinkage was mainly due to the dissolving of MK, where the density of MK plays an important role. The chemical expansion taking place in the second stage was mainly associated with the formation of Al-rich products. The chemical shrinkage in the late age was related to the formation of Si-rich products in literature, but this finding was not confirmed in this study. The understanding of chemical deformation of geopolymers is helpful to explain the autogenous deformation of geopolymers.","","en","conference paper","RILEM Publications S.A.R.L.","","","","","","","","","","Materials and Environment","","",""
"uuid:d8a38fa3-ec4a-45b5-8269-e467fd8fd162","http://resolver.tudelft.nl/uuid:d8a38fa3-ec4a-45b5-8269-e467fd8fd162","Numerical investigation of the SIFs of the external surface crack in rigid pipe reinforced with FRP","Li, Z. (TU Delft Support Marine and Transport Techology); Jiang, X. (TU Delft Transport Engineering and Logistics); Hopman, J.J. (TU Delft Marine and Transport Technology; TU Delft Ship Design, Production and Operations)","","2018","Fatigue is one of the major challenges of offshore rigid pipes. The surface crack is the main manifestation. Fatigue cracks are evolved from surface cracks which are frequently appear in the external surface of rigid pipes. Under fatigue loads, the surface cracks may continue to propagate and finally develop into penetrated cracks, which may cause leakage and serious accidents.
Fiber-reinforced polymer (FRP) strengthening technology is already a reliable technique for structure maintenance in onshore pipelines and penetrated cracks in load-bearing circular hollow sections (CHS). Nevertheless, the research gap of surface crack in rigid pipes reinforced with FRP is seriously restricting the development of FRP reinforcement application.
This paper aims to investigate the surface crack growth in the external surface of rigid pipes reinforced with FRP under bending. Stress intensity factors along the crack front are computed through finite-element (FE) models. The numerical results show that under FRP reinforcement, surface crack growth rate decreases significantly which ensures the safety use of rigid pipes in offshore industry.","offshore rigid pipe; external surface crack; stress intensity factor; finite element method","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.","","2019-06-01","","Marine and Transport Technology","Transport Engineering and Logistics","","",""
"uuid:a8d2e477-bfd4-46ae-9889-1770e8d05144","http://resolver.tudelft.nl/uuid:a8d2e477-bfd4-46ae-9889-1770e8d05144","A spring-supported arch model for predicting the hydrostatic collapse strength of flexible risers with layer gap","Li, X. (TU Delft Marine and Transport Technology); Jiang, X. (TU Delft Transport Engineering and Logistics); Hopman, J.J. (TU Delft Marine and Transport Technology; TU Delft Ship Design, Production and Operations)","","2018","","flexible riser; critical pressure; layer gap; wet collapse; ultra-deep water","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.","","2019-10-01","","Marine and Transport Technology","Transport Engineering and Logistics","","",""
"uuid:39f4142b-23d4-49fb-a6ee-2f80c02b1958","http://resolver.tudelft.nl/uuid:39f4142b-23d4-49fb-a6ee-2f80c02b1958","Comparison of vehicle-track interaction models to simulate vertical wheel/rail impact contact","Shen, C. (TU Delft Railway Engineering); Sabbatini, L. (TU Delft Railway Engineering); Wei, Z. (TU Delft Railway Engineering); Dollevoet, R.P.B.J. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering)","Spiryagin, Maksym (editor); Gordon, Timothy (editor); Cole, Colin (editor); McSweeney, Tim (editor)","2018","This study compares various assumptions in different models to assess their capabilities to model vehicle-track interactions up to 2 kHz at a single rail-top defect. Field measurement data are used to evaluate discrepancies. The characteristics of contact force and axle-box acceleration (ABA) are first identified and qualitatively correlated with track, wheelset and contact models. Subsequently, the results from different models are quantitatively compared in terms of their capabilities to reproduce those characteristics. It is found that the differences in sleeper and wheel-rail contact models lead to the most significant discrepancies. The causes and physical implications of the quantified discrepancies are also discussed.","","en","conference paper","CRC Press","","","","","","","","","","Railway Engineering","","",""
"uuid:55ec6376-f1d7-4c77-97f2-6c669e915007","http://resolver.tudelft.nl/uuid:55ec6376-f1d7-4c77-97f2-6c669e915007","Rail Condition Monitoring using Axle Box Acceleration Measurements: Defect detection in the Netherlands and Romania","Nunez, Alfredo (TU Delft Railway Engineering); Hendriks, J.M. (TU Delft Railway Engineering); Moraal, J. (TU Delft Railway Engineering); Ramirez Fonseca, I. (TU Delft Railway Engineering); Dollevoet, R.P.B.J. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering)","Fu, Z. (editor); Zhou, Z. (editor); Walton, M. (editor)","2018","In this paper we discuss rail condition monitoring based on axle box acceleration (ABA) measurements. We present three case studies. The first one in The Netherlands, the detection of local defects with different severity levels (squat A, squat B and squat C) is analysed. The second case from the Faurei testing ring in Romania, the detection of rail defects over the whole testing ring is presented and examples of responses at a local defect (wheel-burn) is discussed with measurements at 80km/h (conventional speed measurement) and 200km/h (high speed measurement). In the third case, ABA measurements were obtained during operation in a train with passengers in the railway line near Brasov, Bartolomeu-Zărneşti. Examples of the defects and validations are discussed.","","en","conference paper","","","","","","","","","","","Railway 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:5000e635-e70a-42f0-bc8a-b5aefc1ef856","http://resolver.tudelft.nl/uuid:5000e635-e70a-42f0-bc8a-b5aefc1ef856","A condition-based maintenance methodology for rails in regional railway networks using evolutionary multiobjective optimization: Case study line Braşov to Zărneşti in Romania","Nunez, Alfredo (TU Delft Railway Engineering); Jamshidi, A. (TU Delft Railway Engineering); Wang, H. (TU Delft Railway Engineering); Hendriks, J.M. (TU Delft Railway Engineering); Ramirez Fonseca, I. (TU Delft Railway Engineering); Moraal, J. (TU Delft Railway Engineering); Dollevoet, R.P.B.J. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering)","Vellasco, M. (editor); Estevez, P. (editor); Yen, Gary G. (editor)","2018","In this paper, we propose a methodology based on signal processing and evolutionary multiobjective optimization to facilitate the maintenance decision making of infra-managers in regional railways. Using a train in operation (with passengers onboard), we capture the condition of the rails using Axle Box Acceleration measurements. Then, using Hilbert-Huang Transform, the locations where the major risks are detected and ssessed with a degradation model. Finally,
evolutionary multiobjective optimization is employed to solve the maintenance decision problem, and to facilitate the visualization of the trade-offs between number of interventions and performance. Real-life measurements from the track from Braşov to Zărneşti in Romania are included to show the methodology.","Multiobjective optimization; acceleration measurements; Railway Engineering; ARMOEA; KPIs","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.","","2019-01-13","","","Railway Engineering","","",""
"uuid:7020096c-f221-48d4-ad08-bad13ca3599e","http://resolver.tudelft.nl/uuid:7020096c-f221-48d4-ad08-bad13ca3599e","Improved and more complete conceptual model for the revision of IndoorGML","Alattas, A.F.M. (TU Delft OLD Department of GIS Technology; King Abdulaziz University); Zlatanova, S. (University of New South Wales); van Oosterom, P.J.M. (TU Delft OLD Department of GIS Technology); Li, Ki-Joune (Pusan National University)","","2018","With the increasing number of indoor navigation applications, it is essential to have clear and complete conceptual model (in the form of UML class diagram) for IndoorGML. The current version of IndoorGML standard has an incomplete class diagram (incomplete w.r.t. attributes, of which some are appearing in the XML/GML schema), and that provides confusion for the users of the standard. Furthermore, there are some issues related to unclear association names, unclear class names, classes that related to the Primal space and the Dual space, code lists not specific per type (which should have their own code list values), untyped relationships to external object classes, and semantically overlapping classes. In this paper, we propose an enhancement for IndoorGML conceptual model (UML class diagram) to avoid the misunderstanding. We propose a conceptual model that maps the classes of the standard in a better way. This conceptual model is the basis for 1) a database schema when storing IndoorGML data, 2) the XML schema when exchanging IndoorGML data, and 3) when developing IndoorGML applications with an intuitive and clear GUI. Furthermore, the proposed conceptual model provides constraints for more meaningful model and to define more sharply what is considered valid data. This paper briefly reports these preliminary results on the UML conceptual model.","Boundary; CellSpace; Navigation; Space","en","conference paper","Dagstuhl","","","","","","","","","","OLD Department of GIS Technology","","",""
"uuid:32115b67-008b-4111-876d-66be3c8324ca","http://resolver.tudelft.nl/uuid:32115b67-008b-4111-876d-66be3c8324ca","A Functional Architecture of Prognostics and Health Management using a Systems Engineering Approach","Li, R. (TU Delft Air Transport & Operations); Verhagen, W.J.C. (TU Delft Air Transport & Operations); Curran, R. (TU Delft Air Transport & Operations)","","2018","Prognostic and Health Management (PHM) describes a set of capabilities that enable effective and efficient approaches towards data analysis for fault diagnostics and failure prognostics. This can support decision making related to health management, sustainment and operation of critical systems, such as aviation systems. As a result of the rapidly growing interest in PHM, a substantial amount of research proposes and discusses PHM frameworks and system architectures. Previous research efforts conceptual formulation of design methodology to proposes a set of PHM system architectures based on different frameworks, and the derivation of architectures from system requirements. However, further interpretations of PHM system architecture derived from requirements in functional view are lacking. Research on a generic PHM architecture allowing communication and integration with the various contributing systems are lacking. To address these gaps, this research outlines an architecture design methodology incorporating a functional view from a systems engineering perspective. In addition, it proposes a functional architecture for PHM system as the application of the methodology, which has compatibility and interoperability to integrate with the various systems, due to its compliance with the standard of Open System Architecture for Condition-Based Maintenance (OSA-CBM).","","en","conference paper","","","","","","","","","","","Air Transport & Operations","","",""
"uuid:3c1aa42b-1b11-45bf-a18c-3d0d08b2f71a","http://resolver.tudelft.nl/uuid:3c1aa42b-1b11-45bf-a18c-3d0d08b2f71a","Multi-level discrete fracture model for carbonate reservoirs","Li, L. (China University of Petroleum (East China)); Voskov, D.V. (TU Delft Reservoir Engineering)","Gunasekera, D. (editor)","2018","The main challenge for predictive simulation of carbonate reservoirs is associated with large uncertainties in the geological characterization with multiple features including fractures and cavities. This type of reservoirs requires robust and efficient forward-simulation capabilities to apply data assimilation or optimization technique under uncertainties. The interaction between reservoir matrix and various features introduces a complex multi-scale flow response driven by global boundary conditions. The Discrete Fracture Models (DFM), which represent fractures explicitly, is capable to accurately depict all important features of flow behavior. However, these models are constrained by many degrees of freedom when the fracture network becomes complicated. The Embedded DFM, which represents the interaction between matrix and fractures analytically, is an efficient approximation. However, it cannot accurately reproduce the effect of local flow conditions, especially when the secondary fractures are present. In this study, we applied a numerical upscaling of DFM a triple continuum model where large features are represented explicitly using the numerical EDFM and small features are upscaled as a third continuum. In this approach, we discretize the original geo-model with unstructured grid based on DFM and associate the mesh geometry with large features in the model. Using the global solution, we generate local boundary conditions for the model capturing the response of primary features to the flow. Applying local boundary conditions, we resolve all secondary features using a fine scale solution and update the local boundary conditions. This procedure is applied iteratively using the local-global-upscaling formalism. To demonstrate the accuracy of the Multi-Level Discrete Fracture Model, several realistic cases have been tested. By comparing with fine scale DFM solution and the traditional EDFM technique, we demonstrate that the proposed model is accurate enough to capture the flow behavior in complex fractured systems with advanced computational efficiency.","","en","conference paper","EAGE","","","","","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.","","2019-03-06","","","Reservoir Engineering","","",""
"uuid:72b53a35-5428-4c18-93b7-3cd6221b7d76","http://resolver.tudelft.nl/uuid:72b53a35-5428-4c18-93b7-3cd6221b7d76","Decision support tool based on multi-source data analysis for the tram wheel-rail interface","Xie, Wei (Student TU Delft); Nunez, Alfredo (TU Delft Railway Engineering); Maas, Ron (Sensornet); Li, Z. (TU Delft Railway Engineering)","De Schutter, Bart (editor); Ferrara, Antonella (editor)","2018","This paper presents a methodology to support decision making based on the tram wheel-rail interface condition. The methodology relies on the following measurements: tram failure log-files regarding wheel-sliding events, monitored acoustics data and open source weather information. The proposed methodology consists of three stages: 1) data collection and pre-processing, 2) spatial analysis based on clustering, and 3) decision support based on the extracted information. For clustering, the Density-Based Algorithm (DBSCAN) is used for the analysis of wheel-sliding events. Self-organizing maps (SOMs) are employed for the analysis of acoustics data. A real-life case study is used to show how use of the methodology can find interesting hotspots that are candidates for further monitoring and maintenance actions. The measurements were obtained from the tram system in the city of Rotterdam, The Netherlands.","Decision support systems; wheel-rail interface; tram infra maintenance; self-organizing maps; density-based clustering","en","conference paper","Elsevier","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2019-01-19","","","Railway Engineering","","",""
"uuid:275cab72-3be2-4772-9a08-a806b275ad82","http://resolver.tudelft.nl/uuid:275cab72-3be2-4772-9a08-a806b275ad82","Optimization of the Revenue of the New York City Taxi Service using Markov Decision Processes","Bhulai, Sandjai (Vrije Universiteit Amsterdam); Li, P (Vrije Universiteit Amsterdam); van Essen, J.T. (TU Delft Discrete Mathematics and Optimization)","Bhulai, Sandjai (editor); Kardaras, Dimitris (editor)","2017","Taxis are an essential component of the transportation system in most urban centers. The ability to optimize the efficiency of routing represents an opportunity to increase revenues for taxi drivers. The vacant taxis cruising on the roads are not only wasting fuel consumption, the time of a taxi driver, and create unnecessary carbon emissions but also generate additional traffic in the city. In this paper, we use Markov Decision Processes to optimize the revenues of taxi drivers by better routing. We present a case study with New York City Taxi data with several experimental evaluations of our model. We achieve approximately 10\% improvement in efficiency using data from the month of January. The results also provide a better understanding of the several different time shifts. These data may have important implications in the field of self-driving vehicles.","","en","conference paper","IARIA","","","","","","","","","","Discrete Mathematics and Optimization","","",""
"uuid:0a70c37e-0305-4485-b78f-f358f52b4629","http://resolver.tudelft.nl/uuid:0a70c37e-0305-4485-b78f-f358f52b4629","Success factors in the realization of large ice projects in education","Pronk, Arno (Katholieke Universiteit Leuven); Luo, Peng (Harbin Institute of Technology); Li, Q. (TU Delft Structural Design & Mechanics); Sanders, F.C. (TU Delft Environmental Technology and Design); Overtoom, M.E. (TU Delft Indoor Environment); Coar, Lancelot (University of Manitoba)","Bögle, Annette (editor); Grohmann, Manfred (editor)","2017","There has been a long tradition in making ice structures, but the development of technical improvements for making ice buildings is a new field with just a handful of researchers. Most of the projects were realized by professors in cooperation with their students as part of their education in architecture and civil engineering. The following professors have realized ice projects in this setting: Heinz Isler realized some experiments since the 1950s; Tsutomu Kokawa created in the past three decades several ice domes in the north of Japan with a span up to 25 meters; Lancelot Coar realized a number of fabric formed ice shell structures including fiberglass bars and hanging fabric as a mould for an ice shell in 2011 and in 2015 he produced an fabric-formed ice origami structure in cooperation with MIT (Caitlin Mueller) and VUB (Lars de Laet)[4]. Arno Pronk realized several ice projects such as the 2004 artificially cooled igloo, in 2014[1] and 2015[2] dome structures with an inflatable mould in Finland and in 2016 one ice dome and two ice towers in Harbin (China) as a cooperation between the Universities of Eindhoven & Leuven (Pronk) and Harbin (Wu and Luo). In this paper we will present the motivation and learning experiences of students involved in learning-by-doing by realizing one large project in ice. The 2014-2016 projects were evaluated by Sanders and Overtoom[3] using questionnaires among the participants by mixed cultural teams under extreme conditions. By comparing the results in different situations and cultures we have found common rules for the success of those kinds of educational projects. In this paper we suggest that the synergy among students participating in one main project without a clear individual goal can be very large. The paper will present the success factors for projects to be perceived as a good learning experience.","Ice composite structures; learning by doing; group dynamics; synergy in education","en","conference paper","","","","","","","","","","","Structural Design & Mechanics","","",""
"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:d20a4907-a6fb-475f-bc85-0e58409d7aed","http://resolver.tudelft.nl/uuid:d20a4907-a6fb-475f-bc85-0e58409d7aed","Cost-effective design of long spatially variable soil slopes using conditional simulation","Li, Y. (TU Delft Geo-engineering); Hicks, M.A. (TU Delft Geo-engineering); Vardon, P.J. (TU Delft Geo-engineering)","","2017","The three dimensional nature of soil spatial variability implies the need for 3D analysis of geotechnical structures. This paper presents the probabilistic analysis of long slopes such as levees and highway embankments, which are usually analysed unrealistically in plane strain, thereby ignoring the discrete failure mechanisms often encountered in practice. Conditional random fields of soil heterogeneity have been generated based on 3D Kriging, so that they match measurement data at borehole locations and honour the spatial correlations of the soil properties. A simple example involving the cost-effective design of an excavation in a 3D clay deposit has been investigated. It has been demonstrated that, by using conditional random fields within the random finite element method, more cost-effective geotechnical designs can be achieved while maintaining the same calculated reliability.","","en","conference paper","","","","","","","","2018-07-01","","","Geo-engineering","","",""
"uuid:b4b02e39-1323-458e-bb01-be6a1d236bea","http://resolver.tudelft.nl/uuid:b4b02e39-1323-458e-bb01-be6a1d236bea","Educación e investigación en ingeniería ferroviaria: tren de mediciones CTO, una sala de clases sobre rieles","Nunez, Alfredo (TU Delft Railway Engineering); Hendriks, J.M. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering); Dollevoet, R.P.B.J. (TU Delft Railway Engineering)","Rivera-Vargas, P. (editor); Morales-Olivares, R. (editor); Sánchez-Sánchez, E. (editor); Sáez-Rosenkranz, I. (editor)","2017","La industria ferroviaria a nivel mundial necesita de una gran cantidad de nuevos
profesionales, capaces de resolver los crecientes desafíos que este modo presenta. Siendo una industria por lo general conservadora, atraer a las y los mejores no es tarea fácil. En este resumen, se discuten algunos desafíos del mundo ferroviario y se presenta el tren CTO como una manera novedosa de atraer estudiantes. Hasta la fecha, el tren CTO hasido ocupado principalmente para labores de investigación de la universidad tecnológica de Delft y por algunas empresas. Se pretende adaptar el tren para ocuparlo como sala de clases durante el año académico 2017-2018. Siendo un proyecto en desarrollo, el objetivo principal de este resumen es discutir desafíos futuros, adelantar la discusión de la necesidad de formación de nuevos profesionales ferroviarios que se tendrá en Chile y, sobre todo, fomentar la cultura y amor por el modo ferroviario.","","es","conference paper","","","","","","","","","","","Railway Engineering","","",""
"uuid:b3f21d10-cf4c-4dfb-ba23-034071314e38","http://resolver.tudelft.nl/uuid:b3f21d10-cf4c-4dfb-ba23-034071314e38","Design and Experimental Validation of Swirl Recovery Vanes for Propeller Propulsion Systems","Li, Q. (TU Delft Flight Performance and Propulsion); Öztürk, K. (TU Delft Aerospace Engineering); Ragni, D. (TU Delft Wind Energy); Sinnige, T. (TU Delft Flight Performance and Propulsion); Eitelberg, G. (TU Delft Flight Performance and Propulsion); Veldhuis, L.L.M. (TU Delft Flight Performance and Propulsion); Yangang, Wang (Northwestern Polytechnical University)","","2017","","","en","conference paper","American Institute of Aeronautics and Astronautics Inc. (AIAA)","","","","","","","2018-06-09","Aerospace Engineering","","Flight Performance and Propulsion","","",""
"uuid:754027da-0ca8-4064-b312-1cd3ce99da19","http://resolver.tudelft.nl/uuid:754027da-0ca8-4064-b312-1cd3ce99da19","Influencing factors for condition-based maintenance in railway tracks using knowledge-based approach","Jamshidi, A. (TU Delft Railway Engineering); Hajizadeh, S. (TU Delft Railway Engineering); Naeimi, M. (TU Delft Railway Engineering); Nunez, Alfredo (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering)","","2017","In this paper, we present a condition-based maintenance decision method using
knowledge-based approach for rail surface defects. A railway track may contain a considerable number of surface defects which influence track maintenance decisions. The proposed method is based on two sets of maintenance decision factors i.e. (1) defect detection data and (2) prior knowledge of the track. A defect detection model is proposed to monitor surface defects of the track
including squats. The detection model relies on track images and Axle Box Acceleration (ABA) signals to give both positions of severity and defects. To acquire the prior knowledge, a set of track monitoring data is selected. A fuzzy inference model is proposed relying on the maintenance factors
to give the track health condition in a case study of the Dutch railway network. The proposed condition-based maintenance model enables infrastructure manager to prioritize critical pieces of the track based on the health condition.","Condition-based maintenance decision; Rail surface defects; Bayesian model","en","conference paper","","","","","","","","","","","Railway Engineering","","",""
"uuid:3e96ac94-bd80-4ba5-8e7f-75edd350dd42","http://resolver.tudelft.nl/uuid:3e96ac94-bd80-4ba5-8e7f-75edd350dd42","Computation of stress intensity factors in an initiating RCF crack using a 3D modelling approach","Naeimi, M. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering); Dollevoet, R.P.B.J. (TU Delft Railway Engineering)","","2017","","Rolling contact fatigue; Crack; Stress intensity factors; Finite element model","en","conference paper","","","","","","","","","","","Railway Engineering","","",""
"uuid:0b91ec0f-dc99-4c8d-98da-f3c3cd6f16d1","http://resolver.tudelft.nl/uuid:0b91ec0f-dc99-4c8d-98da-f3c3cd6f16d1","String Stability of Heterogeneous Platoons with Non-connected Automated Vehicles","Wang, M. (TU Delft Transport and Planning); Li, Honghai; GAO, Jian; Huang, Zichao; li, Bin; van Arem, B. (TU Delft Transport and Planning)","","2017","It is expected that automated vehicles will gradually penetrate on public roads, resulting in mixed traffic in the next decades. This can impact traffic flow operations, especially the roadway capacity and flow stability. It is of paramount
importance to understand and predict the implications of automated driving systems on traffic flow at the early design phase to avoid disruptive impacts on traffic. String stability properties of automated vehicle platoons are a fundamental
block to understand their traffic flow stability impact. Previous reports on string stability analysis focussed on homogeneous vehicle strings and simplify the time delays in vehicle systems. This work propose an analytical approach to determine string stability conditions for non-connected vehicle platoons with heterogeneous parameters. To this end, a third-order linear vehicle dynamics model is used in the control design and Laplace transform of the spacing and speed error dynamics in time domain to frequency domain enables the determination of sufficient string stability criteria of heterogeneous vehicle strings. The analytical string stability conditions give new insights into the relationship between the string stability properties of vehicle strings in relation to the system properties of time delays and controller design parameters of feedback gains and desired time gap. Analytical results are verified via
systematic simulation of both homogeneous and heterogeneous strings. Simulations demonstrate the predictive power of the analytical string stability conditions.","","en","conference paper","IEEE","","","","","","","","","Transport and Planning","Transport and Planning","","",""
"uuid:f9869d7c-d5bd-49a5-9bd0-6af728857322","http://resolver.tudelft.nl/uuid:f9869d7c-d5bd-49a5-9bd0-6af728857322","About the subdivision of indoor spaces in indoorGML","Diakite, A.A. (TU Delft Urban Data Science); Zlatanova, S. (TU Delft Urban Data Science); Li, Ki-Joune (Pusan National University)","Kalantari, M. (editor); Rajabifard, A. (editor)","2017","Boosted by the dynamic urbanization of cities, indoor environments are getting more and more complex in order to be able to host people properly. While most of our time is spent inside buildings, the need of GIS tools to assist our daily activities that can become tedious, such as indoor navigation or facility management, became more and more urgent. In that perspective, the IndoorGML standard is aiming to address the gaps left by other standards regarding the spatial modelling for indoor navigation. It includes several concepts such as the organization of the spaces into cells along with their network representation and the possibility to represent multiple connected layers. However, being at its first stage, several concepts of the standard could be improved. One of these is the cell subspacing that is not enough discussed in the current version of the standard. In this paper, we explore all the aspects involved in the subdivision process, from the identification of the navigable and non-navigable space cells to the generation of a navigation graph. We propose several criteria on which the indoor sub-spacing can rely to be automatically performed and and illustrate them on a 3D indoor model.","3D indoor; CityGML; IFC; Indoor space; IndoorGML; Navigation graph; subdivision","en","conference paper","ISPRS","","","","","","","","","","Urban Data Science","","",""
"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:3fb51998-287e-4879-a99f-f3d1f7b79ceb","http://resolver.tudelft.nl/uuid:3fb51998-287e-4879-a99f-f3d1f7b79ceb","Results of the ontology alignment evaluation initiative 2017","Achichi, Manel (Université de Montpellier); Cheatham, Michelle (Wright State University); Dragisic, Zlatan (Linköping University); Euzenat, Jérǒme (Université Grenoble Alpes); Faria, Daniel (Instituto Gulbenkian de Ciencia); Ferrara, Alfio (University of Milan); Flouris, Giorgos (Institute of Computer Science-FORTH); Fundulaki, Irini (Institute of Computer Science-FORTH); Harrow, Ian (Pistoia Alliance Inc.); Ivanova, Valentina (Linköping University); Jiménez-Ruiz, Ernesto (Universitetet i Oslo); Kolthoff, Kristian (University of Mannheim); Kuss, Elena (University of Mannheim); Lambrix, Patrick (Linköping University); Leopold, Henrik (Vrije Universiteit Amsterdam); Li, Huanyu (Linköping University); Meilicke, Christian (University of Mannheim); Mohammadi, Majid (TU Delft Information and Communication Technology); Montanelli, Stefano (University of Milan); Pesquita, Catia (University of Lissabon); Saveta, Tzanina (Institute of Computer Science-FORTH); Shvaiko, Pavel (Informatica Trentina); Splendiani, Andrea (Pistoia Alliance Inc.); Stuckenschmidt, Heiner (University of Mannheim); Thiéblin, Elodie (Université de Toulouse); Todorov, Konstantin (Université de Montpellier); Trojahn, Cássia (Université de Toulouse); Zamazal, Ondřej (University of Economics Prague)","","2017","Ontology matching consists of finding correspondences between semantically related entities of different ontologies. The Ontology Alignment Evaluation Initiative (OAEI) aims at comparing ontology matching systems on precisely defined test cases. These test cases can be based on ontologies of different levels of complexity (from simple thesauri to expressive OWL ontologies) and use different evaluation modalities (e.g., blind evaluation, open evaluation, or consensus). The OAEI 2017 campaign offered 9 tracks with 23 test cases, and was attended by 21 participants. This paper is an overall presentation of that campaign.","","en","conference paper","","","","","","","","","","","Information and Communication Technology","","",""
"uuid:c96a17bf-5b7f-4d19-9da6-3d5ec725685c","http://resolver.tudelft.nl/uuid:c96a17bf-5b7f-4d19-9da6-3d5ec725685c","Real-time performance and safety validation of an integrated vehicle dynamic control strategy","Abdul Rachman, Arya Senna (Student TU Delft); Idriz, Adem Ferad (Student TU Delft); Li, Shiqian (General Motors); Baldi, S. (TU Delft Team Bart De Schutter)","Dochain, Denis (editor); Henrion, Didier (editor); Peaucelle, Dimitri (editor)","2017","The state of the art in automotive control has proposed several analytical, simulation and experimental studies of longitudinal adaptive cruise control strategies, and of lateral control strategies. However, methodical integration of these two strategies is to a large extent missing, as well as validation in real-time computing environment of the safety and performance of longitudinal and lateral integrated solutions. This work proposes a real-time validation of an integrated vehicle dynamic control strategy, designed to create safe interaction between longitudinal and lateral controllers: the integrated system is designed, implemented and tested through Dynacar, a real-time simulation environment for the development and validation of vehicle embedded functionalities. The results show that the proposed integrated controller satisfies the performance in terms of real-time computation, path tracking and collision avoidance for various driving situations.","advanced driver assistance systems; lateral vehicle control; longitudinal; real-time validation; vehicle system integration","en","conference paper","Elsevier","","","","","","","","","","Team Bart De Schutter","","",""
"uuid:75e63ca2-de49-453a-9548-d23a68cbd5d1","http://resolver.tudelft.nl/uuid:75e63ca2-de49-453a-9548-d23a68cbd5d1","Indoor Abstract Spaces: Linking IndoorGML and LADM","Zlatanova, S. (TU Delft Urban Data Science); Li, Ki-Joune (Pusan National University); Lemmen, Christiaan (Netherlands Cadastre); van Oosterom, P.J.M. (TU Delft OLD Department of GIS Technology)","van Oosterom, Peter (editor); Dimopoulou, Efi (editor); Fendel, Elfriede M. (editor)","2016","In this paper we investigate the possible synergy between two different but related standards: OGC’s IndoorGML and ISO TC211’s LADM. Both (can) deal with 3D spaces with properties, constraints and associations attached and both can operate with abstract notations of space. But there are also differences, e.g. LADM is a conceptual model, while IndoorGML is also an actual XML schema (technical model), which can be used directly for data exchange and storage. Also, the scope is different; e.g. IndoorGML focuses on indoor spaces,
while LADM addresses all spaces (in principle a complete subdivision of the countries territory, including outdoor, water and surface spaces). LADM models legal and administrative concepts such as use and ownership rights of spaces related to certain parties.
IndoorGML puts emphasis on connectivity of spaces related to the navigability as one of the main use cases. These characteristics make the two standards quite complementary and this motivates our exploration in the combination of both. The spaces defined by LADM are the results of legal/administrative rights, restrictions, responsibilities (largest possible homogeneous spaces with respect to these RRRs). The space subdivision of IndoorGML is based on navigable areas and their connectivity. IndoorGML also recognizes other spaces, called abstract spaces. The paper will compare the space characteristics of the two models and
will explore options to combine the models.","3D Indoor, Space Subdivision Registration, Restrictions, IndoorGML, LADM; Space Subdivision Registration; Restrictions; IndoorGML; LADM","en","conference paper","International Federation of Surveyors (FIG)","","","","","","","","","","Urban Data Science","","",""
"uuid:15060c16-aa0d-458a-9088-54b277fd4c67","http://resolver.tudelft.nl/uuid:15060c16-aa0d-458a-9088-54b277fd4c67","New opportunities with nanowires","Bakkers, E.P.A.M. (TU Delft QN/Bakkers Lab; Eindhoven University of Technology); Hauge, H. I.T. (Eindhoven University of Technology); Li, A. (Eindhoven University of Technology); Assali, S. (Eindhoven University of Technology); Dijkstra, A. (Eindhoven University of Technology); Tucker, R. (Eindhoven University of Technology; University of Alberta); Ren, Y. (Eindhoven University of Technology); Conesa Boj, S. (TU Delft QRD/Kouwenhoven Lab); Verheijen, M. A. (Eindhoven University of Technology; Philips Innovation Services)","","2016","Light emission from Si, would allow integration of electronic and optical functionality in the main electronics platform technology, but this has been impossible due to the indirect band gap of Si. In this talk I will discuss 2 different approaches, using unique properties of nanowires, to realize light emission from Si-based compounds.","","en","conference paper","Institute of Electrical and Electronics Engineers (IEEE)","","","","","","","","","","QN/Bakkers Lab","","",""
"uuid:4ce52b61-e602-4eff-a997-fc2b5ef0026f","http://resolver.tudelft.nl/uuid:4ce52b61-e602-4eff-a997-fc2b5ef0026f","Probabilistic performance assessment of a deep tunnel for a radioactive waste repository in French COx claystone","Li, Y. (TU Delft Geo-engineering); Vardon, P.J. (TU Delft Geo-engineering); Hicks, M.A. (TU Delft Geo-engineering)","Vardon, P.J. (editor); Bykov, D. (editor)","2016","A preliminary probabilistic study of the stability of a circular drift excavated for a radioactive waste repository in the French Callovo-Oxfordian claystone is presented and discussed. An analytical mechanical model assuming isotropic elastic behaviour and linear plastic softening was used. Particular emphasis here is placed on the uncertainty of mechanical property values. The test results from several laboratories showed considerably variable property values and they have been interpreted statistically in this investigation. The obtained statistical results were used in a Monte Carlo framework. The performance of the drift was evaluated in terms of the probability of threshold exceedance in the extent of the plastic zone.","","en","conference paper","Delft University of Technology","","","","","","","","","","Geo-engineering","","",""
"uuid:3460968e-08f0-458d-a67b-3f3e366768b1","http://resolver.tudelft.nl/uuid:3460968e-08f0-458d-a67b-3f3e366768b1","Improved registration of DCE-MR images of the liver using a prior segmentation of the region of interest","Zhang, T. (TU Delft ImPhys/Quantitative Imaging); Li, Z. (National University of Defense Technology); Runge, Jurgen H. (Universiteit van Amsterdam); Lavini, Cristina (Universiteit van Amsterdam); Stoker, Jaap (Universiteit van Amsterdam); Van Gulik, Thomas (Universiteit van Amsterdam); van Vliet, L.J. (TU Delft ImPhys/Quantitative Imaging); Vos, F.M. (TU Delft ImPhys/Quantitative Imaging; Universiteit van Amsterdam)","Styner, Martin A. (editor); Angelini, Elsa D. (editor)","2016","In Dynamic Contrast-Enhanced MRI (DCE-MRI) of the liver, a series of images is acquired over a period of 20 minutes. Due to the patient's breathing, the liver is subject to a substantial displacement between acquisitions. Furthermore, due to its location in the abdomen, the liver also undergoes marked deformation. The large deformations combined with variation in image contrast make accurate liver registration challenging. We present a registration framework that incorporates a liver segmentation to improve the registration accuracy. The segmented liver serves as region-of-interest to our in-house developed registration method called ALOST (autocorrelation of local image structure). ALOST is a continuous optimization method that uses local phase features to overcome space-variant intensity distortions. The proposed framework can confine the solution field to the liver and allow for ALOST to obtain a more accurate solution. For the segmentation part, we use a level-set method to delineate the liver in a so-called contrast enhancement map. This map is obtained by computing the difference between the last and registered first volume from the DCE series. Subsequently, we slightly dilate the segmentation, and apply it as the mask to the other DCE-MRI volumes during registration. It is shown that the registration result becomes more accurate compared with the original ALOST approach.","ALOST; DCE-MRI; Level-set; Liver Segmentation; Registration","en","conference paper","SPIE","","","","","","","","","","ImPhys/Quantitative Imaging","","",""
"uuid:c15161f0-dc0b-4f80-bd21-5c26b34fb753","http://resolver.tudelft.nl/uuid:c15161f0-dc0b-4f80-bd21-5c26b34fb753","Effects of wheelset flexibility on the simulation of vehicle-track interaction at crossings","Shen, C. (TU Delft Railway Engineering); Wei, Z. (TU Delft Railway Engineering); Burgelman, N.D.M. (TU Delft Railway Engineering); Dollevoet, R.P.B.J. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering)","Plochl, M (editor); Rosenberger, M (editor); Six, K (editor); Edelmann, J (editor)","2016","Though numerical models based on multi-body dynamics (MBD) are often used to simulate the vehicle-track interaction at crossing impact, their relative capabilities and accuracy were not discussed. This paper aims to investigate the influence of wheelset flexibility on the result of crossing impact simulation in the frequency range 0–500 Hz. Two models are used: a MBD model with rigid wheelset and a reference finite element model that could fully account for the structural flexibility. Results of the two models as well as in-situ measurement show three characteristic frequencies of the vehicle-track interaction system induced by crossing impact. Based on the characteristic frequencies, the MBD model is tuned to resemble the reference FE model in terms of track and contact representation through a parametric analysis so that the influence of these differences can be isolated. It is found that the major influence of the wheelset flexibility is on the second characteristic frequency of the system, reflecting the second order bending of the wheelset.
3 pag","en","conference paper","CRC Press","","","","","","","","","","Railway Engineering","","",""
"uuid:5cba7406-1f2e-4b8d-8b61-fa2b495b2004","http://resolver.tudelft.nl/uuid:5cba7406-1f2e-4b8d-8b61-fa2b495b2004","Key performance indicators using robust prediction modelling to consider squats in railway infrastructure","Jamshidi, A. (TU Delft Railway Engineering); Nunez, Alfredo (TU Delft Railway Engineering); Molodova, M. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering); Dollevoet, R.P.B.J. (TU Delft Railway Engineering)","Pombo, J (editor)","2016","","Axle box acceleration; Key performance indicators; Measurement;; Squat","en","conference paper","Civil-Comp Press","","","","","Accepted Author Manuscript, Paper 159","","","","","Railway Engineering","","",""
"uuid:89dbc441-5095-4b15-abe9-34bbba4165c2","http://resolver.tudelft.nl/uuid:89dbc441-5095-4b15-abe9-34bbba4165c2","An approach on form-diversity of free-form shells generated from numerical hanging models","Li, Q. (TU Delft Structural Design & Mechanics); Borgart, A. (TU Delft Structural Design & Mechanics); Wu, Y (Harbin Institute of Technology)","Kawaguchi, K. (editor); Ohsaki, M. (editor); Takeuchi, T. (editor)","2016","","form-finding; free-form shells; form-diversity; numerical hanging models","en","conference paper","IASS","","","","","","","","","","Structural Design & Mechanics","","",""
"uuid:d5becc4b-80d0-46af-a64e-6288c6e7b1f7","http://resolver.tudelft.nl/uuid:d5becc4b-80d0-46af-a64e-6288c6e7b1f7","LANDM and IndoorGML for support of Indoor Space identification","Zlatanova, S. (TU Delft Urban Data Science); van Oosterom, P.J.M. (TU Delft OLD Department of GIS Technology); Lee, J (University of Seoul); Li, Ki-Joune (Pusan National University); Lemmen, C. H. J. (Netherlands Cadastre)","Dimopoulou, E. (editor); van Oosterom, P. (editor)","2016","Guidance and security in large public buildings such as airports, museums and shopping malls requires much more information that traditional 2D methods offer. Therefore 3D semantically-reach models have been actively investigated with the aim to gather knowledge about availability and accessibility of spaces. Spaces can be unavailable to specific users because of plenty of reasons: the 3D geometry of spaces (too low, too narrow), the properties of the objects to be guided to a specific part of the building (walking, driving, flying), the status of the indoor environment (e.g. crowded, limited light, under reconstruction), property regulations (private areas), security considerations and so on.
However, such information is not explicitly avaible in the existing 3D semantically-reach models. IFC and CityGML are restricted to architectural building components and provide little to no means to describe such properties. IndoorGML has been designed to establish a generic approach for space identification allowing a space subdivision and automatic creation of a network for route computation. But currently it also represents only spaces as they are defined by the architectural layout of the building. The Land Administration Domain Model is currently the only available model to specify spaces on the basis of ownership and rights for use.
In this paper we compare the principles of IndoorGML and LADM, investigate the approaches to define spaces and suggest options to the linking of the two types of spaces. We argue that LADM space subdivision on basis of properties and rights of use can be used to define to semantically and geometrically available and accessible spaces and therefore can enrich the IndoorGML concept.","Space subdivision; spatial units; rights; indoor; navigation; land administration; building model","en","conference paper","ISPRS","","","","","","","","","","Urban Data Science","","",""
"uuid:4d601160-6fda-48eb-ac4e-994ba69301f8","http://resolver.tudelft.nl/uuid:4d601160-6fda-48eb-ac4e-994ba69301f8","Conceptualization of a real-time information processing platform for context-aware informing cyber-physical systems","Li, Y. (TU Delft Cyber-Physical Systems; Harbin Institute of Technology); Horvath, I. (TU Delft Cyber-Physical Systems); Rusak, Z. (TU Delft Cyber-Physical Systems); van der Vegte, Wilhelm Frederik (TU Delft Cyber-Physical Systems); Zhang, Guangjun (Harbin Institute of Technology)","Horvath, I. (editor); Pernot, J.-P. (editor); Rusák, Z. (editor)","2016","Informing cyber-physical systems (I-CPSs) are designed to accomplish sensing, reasoning and informing activities in dynamic context. In order to
simplify and accelerate the design and implementation process of multiple context-aware ICPSs, we are developing an information sensing,
computing and actuating (SCA) platform that can be used as a central module of these systems. This paper presents the concept of a SCA platform. The
functionality of the platform includes development of context-dependent strategies to adapt the sensing, reasoning and informing behaviors of the platform to various dynamic contexts. There are four constituents of the platform: (1) a generic kernel, (2) built-in elements, (3) add-on components, and (4) system interfaces. The paper also discusses both the internal and external integration mechanism of the SCA platform, which can be customized according to the needs of specific I-CPS applications by extending the generic kernel with various functional built-in elements and add-on components. The feasibility and
applicability of the platform have been tested through a case study: an indoor fire evacuation guiding system. The proposed platform provides a useful package of functionalities, alleviates the burden of developers, and speeds up the development of applications specific context-aware I-CPS.","Informing cyber-physical systems; SCA platform; context aware computing; applications development","en","conference paper","Organizing Committee of TMCE 2016","","","","","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","","2017-12-31","","","Cyber-Physical Systems","","",""
"uuid:e03b8bd2-cfa7-4c27-9cde-816600e4eac8","http://resolver.tudelft.nl/uuid:e03b8bd2-cfa7-4c27-9cde-816600e4eac8","Yaw-misalignment and its impact on wind turbine loads and wind farm power output","van Dijk, M.T. (Student TU Delft); van Wingerden, J.W. (TU Delft Team Raf Van de Plas); Ashuri, T. (Arkansas Tech University); Li, Y. (University of Texas at Dallas); Rotea, M.A. (University of Texas at Dallas)","Bossanyi, E. (editor); Chaviaropoulos, T. (editor); Cheng, P.W. (editor)","2016","To make wind energy cost competitive with traditional resources, wind turbines are commonly placed in groups. Aerodynamic interaction between the turbines causes sub-optimal energy production. A control strategy to mitigate these losses is by redirecting the wake by yaw misalignment. This paper aims to assess the influence of load variations of the rotor due to partial wake overlap and presents a combined optimization of the power and loads using wake redirection. For this purpose, we design a computational framework which computes the wind farm power production and the wind turbine rotor loads based on the yaw settings. The simulation results show that partial wake overlap can significantly increase asymmetric loading of the rotor disk and that yaw misalignment is beneficial in situations where the wake can be sufficiently directed away from the downstream turbine.","","en","conference paper","IOP Publishing","","","","","","","","","","Team Raf Van de Plas","","",""
"uuid:af5ee6f4-718b-4f41-820c-65e752408e3d","http://resolver.tudelft.nl/uuid:af5ee6f4-718b-4f41-820c-65e752408e3d","Probabilistic defect-based risk assessment approach for rail failures in railway infrastructure","Jamshidi, A. (TU Delft Railway Engineering); Faghih Roohi, S. (TU Delft Team Bart De Schutter); Nunez, Alfredo (TU Delft Railway Engineering); Babuska, R. (TU Delft OLD Intelligent Control & Robotics); De Schutter, B.H.K. (TU Delft Team Bart De Schutter); Dollevoet, R.P.B.J. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering)","Acarman, Tankut (editor)","2016","This paper develops a defect-based risk analysis methodology for estimating rail failure risk. The methodology relies on an evolution model addressing the severity level of rail surface defect, called squat. The risk of rail failure is assessed by analyzing squat failure probability using a probabilistic analysis of the squat cracks. For this purpose, a Bayesian inference method is employed to capture a robust model of squat failure probability when the squat becomes severe. Moreover, an experimental correlation between squat visual length and squat crack depth is obtained in order to define four severity categories. Relying on the failure probability and the severity categories of the squats, risk of future failure is categorized in three different scenarios (optimistic, average and pessimistic). To show the practicality and efficiency of the proposed methodology, a real example is illustrated.","imbalance data; semi-supervised learning; rail image data; rail defect detection","en","conference paper","Elsevier","","","","","","","","","","Railway Engineering","","",""
"uuid:773cdcc9-f82e-47ff-a4d1-e7efb111047e","http://resolver.tudelft.nl/uuid:773cdcc9-f82e-47ff-a4d1-e7efb111047e","Environmental degradation of adhesively-bonded composite joints","Li, C.; Rans, C.D.; LaPlante, G.; Marsden, C.","","2015","","adhesive bonding; fracture; composites","en","conference paper","University of Alberta","","","","","","","","Aerospace Engineering","Aerospace Structures & Materials","","","",""
"uuid:8e0ed5f8-fded-493d-9453-66833582f83b","http://resolver.tudelft.nl/uuid:8e0ed5f8-fded-493d-9453-66833582f83b","Image registration based on the structure tensor of the local phase","Li, Z.; Van Vliet, L.J.; Stoker, J.; Vos, F.M.","","2015","Image registration of medical images in the presence of large intra-image signal fluctuations is a challenging task. Our paper addresses this problem by introducing a new concept based on the structure tensor of the local phase. The local phase is calculated from the monogenic signal representation of the images. The local phase image is hardly affected by unwanted signal fluctuations due to a space-variant background and a space-variant contrast. The boundary structure tensor combines the responses of edges and corners/junctions in one tensor, which has several advantages, compared to other structure tensors. We reorient the structure tensor during the registration by means of the finite-strain technique. The structure tensor is only calculated once during a preprocessing step. The results demonstrate that the proposed method effectively deals with large signal fluctuations. It performs significantly better than competing techniques.","monogenic signal; tensor reorientation; structure-based registration","en","conference paper","SPIE","","","","","","","","Applied Sciences","ImPhys/Imaging Physics","","","",""
"uuid:8c58f186-5559-408b-af01-42dd783cb690","http://resolver.tudelft.nl/uuid:8c58f186-5559-408b-af01-42dd783cb690","Liquid water permeability of partially saturated cement paste assessed by dem-based methodology","Li, K.; Stroeven, P.; Stroeven, M.; Sluys, L.J.","","2015","Permeability of virtual cement seems to exceed experimental data by several orders of magnitude. The differences may actually not be that dramatic, since experimental samples are in practice not always fully saturated as generally assumed. This paper demonstrates that this has enormous effects on permeability. A numerical study is conducted on water permeability of partially saturated cement paste based on simulated microstructures. During drying, larger pores empty first according to the Kelvin-Laplace law, leading to a significant decline in water permeability. The results in terms of relative water permeability have been validated against lattice Boltzmann simulations and experimental data, respectively. A satisfactory agreement is found. Both the pore size distribution and pore connectivity are shown to have an important influence on the overall permeability. The effects of technological parameters, such as hydration age and water-to-cement ratio, have also been discussed.","cement paste; water permeability; water saturation degree; pore network; DEM; particle simulation","en","conference paper","Institute of Fundamental Technological Research PAS","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:b9ba2851-9eb6-47cf-912e-be768fc662aa","http://resolver.tudelft.nl/uuid:b9ba2851-9eb6-47cf-912e-be768fc662aa","Conceptual design of a high discharge barrier in the closed-open-super dike ring ""Rijnmond"" (abstract)","Siverd, C.; Arecco, P.; Li, Y.; Van der Toorn, A.","","2015","","","en","conference paper","PIANC","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:b8fe63ad-cbd9-4f42-a286-dd42a5e3d32a","http://resolver.tudelft.nl/uuid:b8fe63ad-cbd9-4f42-a286-dd42a5e3d32a","Computation of the flash-temperature at the wheel-rail contact using a 3D finite element model and its comparison with analytical methods","Naeimi, M.; Li, Z.; Dollevoet, R.P.B.J.; Wu, J.; Petrov, R.H.; Sietsma, J.","","2015","The coupled mechanical–thermal behaviour of wheel and rail materials under rolling contact is studied to determine the temperature rise due to the frictional heat. The wheel–rail frictional rolling contact problem is solved using the three–dimensional finite element (FE) method. The FE model considers the wheel tread–rail top contact with partial-slip and converts the frictional energy into the heat as an attempt to estimate the temperature rise. Instead of assuming a global sliding velocity (a conventional premise in the field), the relative velocities of wheel-rail nodes in the contact patch are automatically taken into account in the coupled analysis (instantaneous micro-slip in contact points). Different levels of traction forces are studied which determine the amounts of frictional energy. The thermal properties are specified for the materials. Defining the contact regions of the wheel and rail as the thermal conduction boundary conditions, the frictional energy is converted into heat within the contact interface. After generating the energy flux, the heat conduction occurs in three dimensions both in the wheel and rail. A steady state implicit analysis is considered for the thermal solver, whereas the mechanical solver benefits from an explicit solution scheme. Distributions of stresses and temperatures in the contact patch are made available by analysing various loading conditions. Considering the formulations offered by three analytical methods in the literature, the results of rail temperature i.e. longitudinal distributions and peak values are calculated. Though they are much more simplified problems, these analytical methods are considered as the reference models (benchmark) for comparison. The same input data are used for all the reference models to enable the comparison. The outputs of numerical simulations are compared with the reference data, with discussion on similarities and discrepancies. The proposed model is able to calculate the flash-temperature in wheel and rail materials by dropping some of the conventional assumptions used in the analytical approaches.","flash-temperature; frictional heat; wheelrail contact; finite element method","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:f78ebff2-89e3-4e40-8963-3cdccca2af90","http://resolver.tudelft.nl/uuid:f78ebff2-89e3-4e40-8963-3cdccca2af90","The influence of friction coefficient and wheel/rail profiles on energy dissipation in the wheel/rail contact","Idarraga Alarcon, G.A.; Burgelman, N.D.M.; Meza Meza, J.; Toro, A.; Li, Z.","","2015","This work investigates the energy dissipation in a wheel/rail system through friction work modeling. In order to identify the effect of the friction coefficient on the energy dissipation in the wheel/rail contact, several simulations were performed using a 3D multibody model of a railway vehicle implemented in the software package VI-Rail Adams, with a friction coefficient varying from 0.2 to 0.7.The energy dissipation and wear rates of the inner and outer wheels of the first bogie of the vehicle running over a curve of a metro line were calculated for different friction coefficients. The total frictional work was obtained from the resultant force and slip in a reference point. The wear was also analyzed according to the T? method including the spin, in combination with Kalker’s simplified theory Fastsim, assuming that the wear is proportional to the frictional work. Two sets of rail and wheel profiles were studied in order to determine the effect of the profile’s quality on the energy dissipation and wear rates. To such an end simulations and energy calculations were performed with a friction coefficient of 0.4","multi-body simulation; energy dissipation; frictional work; wear; Wheel and Rail Profiles Quality","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:34dd249e-600c-40cb-9850-0037f8485dfc","http://resolver.tudelft.nl/uuid:34dd249e-600c-40cb-9850-0037f8485dfc","The Vector Form Intrinsic Finite Element method and several other form-finding methods for general networks","Li, Q. (TU Delft Structural Design & Mechanics; Harbin Institute of Technology); Borgart, A. (TU Delft Structural Design & Mechanics); Wu, Yue (Harbin Institute of Technology)","","2015","Discrete networks is a kind of form-active structural system which actively change its shape under varying load conditions. And for this kind of structural system, form-finding is the initial and essential part in their design process. Before the computer age, people complete the form-finding process using physical models, while with the advances in computational techniques, the research has focused on the numerical form-finding methods since the 1960s. A brief discussion on several numerical formfinding methods is presented in this paper. Firstly, two relatively mature numerical method, Dynamic Relaxation method and Force Density method, are introduced conceptually. And then, a newly developed numerical method, the Vector Form Intrinsic Finite Element method, is presented in more detail. At last, with a replacement of the calculation of the internal force of the element which obeys the Hooke's Law by the product of the force density and the length of the element, two derived methods based on the above three methods are proposed in this paper. Moreover, several numerical examples of hanging networks are shown to illustrate the validity and characteristic of the VFIFE method and the two newly proposed derived methods.","form-finding; general networks; Dynamic Relaxation method; Force Density method; Vector Form Intrinsic Finite Element method; derived methods","en","conference paper","","","","","","","","","","","Structural Design & Mechanics","","",""
"uuid:2cca6b39-e76f-4445-8c62-5cf46786aca6","http://resolver.tudelft.nl/uuid:2cca6b39-e76f-4445-8c62-5cf46786aca6","Form-finding of gridshells generated from hanging-chain models by using the Dynamic Relaxation method and the NURBS technique","Li, Q. (TU Delft Structural Design & Mechanics; Harbin Institute of Technology); Wu, Yue (Harbin Institute of Technology); Borgart, A. (TU Delft Structural Design & Mechanics)","","2015","Hanging models play an important role in shaping a structure since a very early age, and were favored by A. Gaudi, H. Isler, F. Otto and other architects or engineers. Nowadays, with the development of numerical analysis theory and computer technique, it is more accurate and convenient to simulate these physical models via numerical means. Based on the background, this paper presents a numerical form-finding method of gridshell structures generated from hanging-chain models by using Dynamic Relaxation method and the NURBS technique, which aims to obtain more complex structural forms with multiple control points.
This method uses global NURBS surface interpolation to describe the initial cable-net model passing through the given target points, which serve as the fitting points of the NURBS surface. The cable elements of the cable-net are not allowed to elongate after form-finding, and clearly, this kind of cable-nets belongs to geometrically unstable system, whose form-finding process of it has a very strong nonlinearity. To solve this problem, it uses the Dynamic Relaxation method, which can complete the form-finding of geometrically unstable systems but with some special sets, to get the equilibrium form of the hanging cable-net under the gravity. However, this structural form may no longer pass through the given target points, and then it introduces the inverse iteration method to adjust the coordinates of the fitting points of the NURBS, which actually means to find the initial structural form which after form-finding can just right meet the target requirements. At last, some numerical examples are presented to demonstrate the validity of the proposed method in this paper.","form-finding; gridshells; hanging-chain models; Dynamic Relaxation method; NURBS; inverse iteration method","en","conference paper","","","","","","","","","","","Structural Design & Mechanics","","",""
"uuid:56802331-af28-49f3-b29d-8f2630c48976","http://resolver.tudelft.nl/uuid:56802331-af28-49f3-b29d-8f2630c48976","Nucleation of squat cracks in rail, calculation of crack initiation angles in three dimensions","Naeimi, M.; Li, Z.; Dollevoet, R.P.B.J.","","2015","A numerical model of wheel-track system is developed for nucleation of squat-type fatigue cracks in rail material. The model is used for estimating the angles of squat cracks in three dimensions. Contact mechanics and multi-axial fatigue analysis are combined to study the crack initiation mechanism in rails. Nonlinear material properties, actual wheel-rail geometries and realistic loading conditions are considered in the modelling process. Using a 3D explicit finite element analysis the transient rolling contact behaviour of wheel on rail is simulated. Employing the critical plane concept, the material points with the largest possibility of crack initiation are determined; based on which, the 3D orientations/angles of the possible squat cracks are estimated. Numerical estimations are compared with sample results of experimental observations on a rail specimen with squat from the site. The findings suggest a proper agreement between results of modelling and experiment. It is observed that squat cracks initiate at an in-plane angle around 13°-22° relative to the rail surface. The initiation angle seen on surface plane is calculated around 29°-48°, while the crack tend to initiate in angles around 25°-31° in the rail cross-section.","","en","conference paper","IOP Publishing","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"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:2f876937-22d3-42fc-8bd4-450a2f8c67ee","http://resolver.tudelft.nl/uuid:2f876937-22d3-42fc-8bd4-450a2f8c67ee","A large-scale study of agents learning from human reward (Extended abstract)","Li, G.; Hung, H.S.; Whiteson, S.","","2015","The TAMER framework, which provides a way for agents to learn to solve tasks using human-generated rewards, has been examined in several small-scale studies, each with a few dozen subjects. In this paper, we present the results of the first large-scale study of TAMER, which was performed at the NEMO science museum in Amsterdam and involved 561 subjects. Our results show for the first time that an agent using TAMER can successfully learn to play Infinite Mario, a challenging reinforcement-learning benchmark problem based on the popular video game, given feedback from both adult (N = 209) and child (N = 352) trainers. In addition, our study supports prior studies demonstrating the importance of bidirectional feedback and competitive elements in the training interface. Finally, our results also shed light on the potential for using trainers’ facial expressions as a reward signal, as well as the role of age and gender in trainer behavior and agent performance.","","en","conference paper","AAMAS","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Intelligent Systems","","","",""
"uuid:8f5c33a5-b6fe-4ec2-a222-629ad729a9a7","http://resolver.tudelft.nl/uuid:8f5c33a5-b6fe-4ec2-a222-629ad729a9a7","Estimation of train dwell time at short stops based on track occupation event data","Li, D.; Daamen, W.; Goverde, R.M.P.","","2015","Train dwell time is one of the most unpredictable components of railway operations mainly due to the varying volumes of alighting and boarding passengers. For reliable estimations of train running times and route conflicts on main lines it is however necessary to obtain accurate estimations of dwell times at the intermediate stops on the main line, the so-called short stops. This is a big challenge for a more reliable, efficient and robust train operation. Previous research has shown that dwell time is highly dependent on the number of boarding and alighting passengers. However, the latter numbers are usually not available in real time. This paper discusses the possibility of a dwell time estimation model at short stops without passenger demand information, by means of a statistical analysis of track occupation data from the Netherlands. The analysis showed that the dwell times are best estimated for peak and off-peak hour separately. The peak hour dwell times are estimated using a linear regression model of train length, dwell times at previous stops and dwell times of the previous trains. The off-peak hour dwell times are estimated using a non-parametric regression model. There are two major advantages of the proposed estimation model. The model does not need passenger flow data which is usually impossible to know in real time in practice. Also, detailed parameters of rolling stock configuration and platform layout are not required, which eases implementation.","prediction; dwell time; short stops; track occupation; data mining","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Transport & Planning","","","",""
"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:aae02b54-c71a-4b77-9bf6-ef762615958c","http://resolver.tudelft.nl/uuid:aae02b54-c71a-4b77-9bf6-ef762615958c","Maintenance decision indicators for treating squats in railway infrastructures","Jamshidi, A.; Nunez, A.A.; Li, Z.","","2015","","","en","conference paper","TRB","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:4e2b5423-1073-43c8-8e1a-7a3477802c33","http://resolver.tudelft.nl/uuid:4e2b5423-1073-43c8-8e1a-7a3477802c33","Numerical study on two-point contact by an explicit integration finite element method: A contribution to the modeling of flange squeal","Yang, Z. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering); Dollevoet, R.P.B.J. (TU Delft Railway Engineering)","Tournay, H (editor); Grassie, S (editor)","2015","The precise mechanism which activates squeal, especially flange squeal has not been fully explained. The complex non-Hertzian contact and the broad-band high frequency feature bring great challenges to the modelling work of flange squeal. In this paper, an explicit integration finite element method is presented to simulate the dynamic curving behavior of the outer wheel, which is believed directly related to flange squeal generation. By fully considering the normal, tangential force and spin moment, the non-steady-state wheel-rail interaction from one-point to two-point contact is reproduced. The critical time step of the explicit integration scheme is determined by the Courant stability condition, which, together with the detailed modelling of the structural and continuum of the wheel/track system, effectively guarantees that the reproduced vibration frequency can reach up to 10 kHz with desired accuracy. The aim of the work is to contribute to the modelling and understanding of the generation mechanism of the flange squeal from the viewpoint of the wheel-rail interaction.","","en","conference paper","Transportation Technology Center - AAR","","","","","","","","","","Railway Engineering","","",""
"uuid:52942d9d-e4ac-4ea9-b9a3-15c9b7901ba9","http://resolver.tudelft.nl/uuid:52942d9d-e4ac-4ea9-b9a3-15c9b7901ba9","Single-Frequency L5 PPP-RTK with GPS, IRNSS, QZSS and Galileo","Li, W. (Curtin University); Nadarajah, N (Curtin University); Teunissen, P.J.G. (TU Delft Mathematical Geodesy and Positioning); Khodabandeh, A. (Curtin University)","","2015","The concept of PPP-RTK is to achieve integer ambiguity resolution (IAR) at a single GNSS user by providing network-derived satellite phase biases (SPBs) in addition to the standard precise point positioning (PPP) corrections. These corrections enable recovering integerness of user ambiguities, thereby recovering the full capability of the precise carrier-phase observations. This contribution analyzes the capability of single-receiver positioning with IAR using new L5/E5a-frequency observations from GPS, the European Galileo, the Japanese quasi-zenith satellite system (QZSS) and the Indian regional navigation satellite system (IRNSS). In the absence of network products for new systems, especially for IRNSS, we use a small array of multi-GNSS stations to provide a batch of network-derived corrections. These array-aided corrections, comprising estimable combinations of the satellite clocks, first-order slant ionospheric delays as well as the satellite phase biases, are applied to the multi-system single-frequency L5/E5a-observations of the user station. Results from real-data experiments demonstrate that even though standalone PPP-RTK using current L5/E5a-enabled satellite sets of each single system is not possible yet, they effectively contribute to the tightly integrated multi-system PPR-RTK.","","en","conference paper","Institute of Navigation","","","","","","","","","","Mathematical Geodesy and Positioning","","",""
"uuid:6500a592-c3a8-4f30-93e5-43474f0ed815","http://resolver.tudelft.nl/uuid:6500a592-c3a8-4f30-93e5-43474f0ed815","A numerical study of unsteady cavitation on a hydrofoil by les and URANS method","Li, Zi Ru (Wuhan University of Technology); Zhang, Guang Ming (Wuhan University of Technology); He, Wei Dong (Wuhan University of Technology); van Terwisga, T.J.C. (TU Delft Ship Hydromechanics and Structures; Maritime Research Institute Netherlands (MARIN))","Farhat, M. (editor); Müller, A. (editor)","2015","In this paper, the unsteady cavitation phenomena on a NACA0015 hydrofoil is numerically simulated by unsteady Reynolds-Averaged Navier-Stokes (URANS) method and Large Eddy Simulation (LES) in single-fluid approaches to multiphase modelling, respectively. It is observed that the large-scale structures and characteristic periodic shedding predicted by the URANS with the modified SST k-ω turbulence model show a good qualitative match with the experimental observations but with quantitative discrepancies, such as a different cavity length and volume, and a different location of shedding. Compared to the URANS results, the LES results reproduce more details of unsteady dynamics with an improved quantitative agreement.","","en","conference paper","IOP Publishing","","","","","","","","","","Ship Hydromechanics and Structures","","",""
"uuid:e29d969d-425f-4673-ae7e-9703ccfb2982","http://resolver.tudelft.nl/uuid:e29d969d-425f-4673-ae7e-9703ccfb2982","Substantial Fatigue Similarity of a New Small-Scale Test Rig to Actual Wheel-Rail System","Naeimi, M.; Li, Z.; Petrov, R.H.; Dollevoet, R.P.B.J.; Sietsma, J.; Wu, J.","","2014","The substantial similarity of fatigue mechanism in a new test rig for rolling contact fatigue (RCF) has been investigated. A new reduced-scale test rig is designed to perform controlled RCF tests in wheel-rail materials. The fatigue mechanism of the rig is evaluated in this study using a combined finite element-fatigue prediction approach. The influences of loading conditions on fatigue crack initiation have been studied. Furthermore, the effects of some artificial defects (squat-shape) on fatigue lives are examined. To simulate the vehicle-track interaction by means of the test rig, a threedimensional finite element (FE) model is built up. The nonlinear material behaviour of the rail steel is modelled in the contact interface. The results of FE simulations are combined with the critical plane concept to determine the material points with the greatest possibility of fatigue failure. Based on the stress-strain responses, by employing of previously postulated criteria for fatigue crack initiation (plastic shakedown and ratchetting), fatigue life analysis is carried out. The results are reported for various loading conditions and different defect sizes. Afterward, the cyclic mechanism of the test rig is evaluated from the operational viewpoint. The results of fatigue life predictions are compared with the expected number of cycles of the test rig by its cyclic nature. Finally, the estimative duration of the experiments until fatigue crack initiation is roughly determined.","fatigue; test rig; crack initiation; life; rail; squats","en","conference paper","World Academy of Science, Engineering and Technology (WASET)","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:6bb36d62-07ed-49f5-9176-c9c5d8e2dfa1","http://resolver.tudelft.nl/uuid:6bb36d62-07ed-49f5-9176-c9c5d8e2dfa1","Scaling strategy of a new experimental rig for wheel-rail contact","Naeimi, M.; Li, Z.; Dollevoet, R.P.B.J.","","2014","A new small–scale test rig developed for rolling contact fatigue (RCF) investigations in wheel–rail material. This paper presents the scaling strategy of the rig based on dimensional analysis and mechanical modelling. The new experimental rig is indeed a spinning frame structure with multiple wheel components over a fixed rail-track ring, capable of simulating continuous wheelrail contact in a laboratory scale. This paper describes the dimensional design of the rig, to derive its overall scaling strategy and to determine the key elements’ specifications. Finite element (FE) modelling is used to simulate the mechanical behavior of the rig with two sample scale factors of 1/5 and 1/7. The results of FE models are compared with the actual railway system to observe the effectiveness of the chosen scales. The mechanical properties of the components and variables of the system are finally determined through the design process.","new test rig; rolling contact fatigue; rail; small scale","en","conference paper","World Academy of Science, Engineering and Technology (WASET)","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:10b5803e-bb9c-4f9b-8d52-a8e26ea7b06b","http://resolver.tudelft.nl/uuid:10b5803e-bb9c-4f9b-8d52-a8e26ea7b06b","Strategy for predicting transport-based durability properties of concrete based on DEM approach","Li, K.; Stroeven, P.; Stroeven, M.","","2014","","","en","conference paper","RILEM","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:29f474a4-b081-4a2a-82b9-cb1ad3605433","http://resolver.tudelft.nl/uuid:29f474a4-b081-4a2a-82b9-cb1ad3605433","Residual fatigue life evaluation of rail at squats seeds using 3D explicit finite element analysis","Deng, X.; Naeimi, M.; Li, Z.; Qian, Z.","","2014","A modeling procedure to predict the residual fatigue life of rail at squats seeds is developed in this article. Two models are involved: a 3D explicit Finite Element (FE) model to compute the stress and strain at squats in rail, and the J-S fatigue damage model to determine the residual fatigue life on the basis of the computed stress and strain. In the FE model dynamic effects of wheel-rail system under rolling contact is taken into account. Bilinear isotropic elastic-plastic material properties are adopted to represent the hardening of wheel and rail. Squats are subject to multiple loading cycles. The geometry of the squat is varied in the simulation corresponding to a growing squat at different ages. It is found that small squats lead to fatigue failure while severe ones lead to ratcheting failure.","fatique life; finite element method; rolling contact fatigue; cracks initiation; rail squats","en","conference paper","DCMat Ageing Centre, Delft University of Technology","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:fa858dbc-9a1c-4ae6-8bed-8ae9b6ecc7eb","http://resolver.tudelft.nl/uuid:fa858dbc-9a1c-4ae6-8bed-8ae9b6ecc7eb","Current status of robotic stroke rehabilitation and opportunities for a cyber-physically assisted upper limb stroke rehabilitation","Li, C.; Rusak, Z.; Horvath, I.; Ji, L.; Hou, Y.","","2014","In the last two decades, robotics-assisted stroke reha-bilitation has been wide-spread, in particular for movement rehabilitation of upper limbs. Several studies have reported on the clinical effectiveness of this kind of therapy. The results of these studies show that robot assisted therapy can be more effective in recovering motor control abilities than conventional therapy. On the other hand, studies found no signifi-cant improvement on motor function abilities of pa-tients. These contradictory results stimulated our re-search to survey current status of robotics-assisted rehabilitation and to look for advancement opportuni-ties. We developed a reasoning model that help us conduct the study systematically and to consider the four most important aspects, namely (i) the post-stroke pathophysiological status of patients, (ii) the nature of the rehabilitation therapies, (iii) the versatil-ity of the robotic rehabilitation instruments, and (iv) the kind of stimulation provided for patients. Our major finding is that there are strong evidences that the efficacy of robotics-assisted rehabilitation can be increased by motivation and engagement. We con-cluded that by exploiting the opportunities offered by cyber-physical systems and gamification, a signifi-cant improvement of context sensitive engagement can be realized. Our follow-up research will study various implementation opportunities, the affordabilities of various cyber-physical solutions, and in-fluence on patients.","Stroke rehabilitation; robotic rehabilitation; rehabili-tation program; motivation and engagement; cyber physical system","en","conference paper","TMCE","","","","","","","","Industrial Design Engineering","Design Engineering","","","",""
"uuid:910fbe01-d6f6-4a58-87a9-b2420b76fe2b","http://resolver.tudelft.nl/uuid:910fbe01-d6f6-4a58-87a9-b2420b76fe2b","Development of a framework for information acquisition and processing in cyber-physical systems","Li, Y.; Song, Y.; Horvath, I.; Opiyo, E.Z.; Zhang, G.","","2014","In the designing and modeling of CPSs, the information acquisition and processing processes are often application dependent and process oriented. Those information management frameworks are simple and effective for small scale systems. However, many functions developed are not reusable or cannot be directly re-used, when a large number of details and relations need to be added. Aiming at designing a flexible and scalable system with “plug-and-play” components, a preliminary information acquisition and processing framework for CPSs is proposed in this paper based on the object oriented design (OOD) method. The concept of informational hierarchy within CPSs is identified first. Then it is further elaborated as instantaneous information, dynamic information and context information. Using these three types of information, together with the physical properties of a component in CPSs, the concept of hybrid object is proposed as the basic component of the proposed framework. By defining the inherent and update operation of hybrid objects, the proposed information acquisition and processing framework is formed with hierarchical hybrid objects. To verify the effectiveness and the efficiency of the proposed framework, a case study on designing and modeling a gas metal arc welding (GMAW) based rapid manufacturing system is presented. Limitations of the proposed framework and future research directions are discussed as well.","Information acquisition and processing framework; object oriented design; hybrid object; plug-and-play; cyber-physical systems","en","conference paper","TMCE","","","","","","","","Industrial Design Engineering","Design Engineering","","","",""
"uuid:ad66900b-93ea-439b-8a32-d8b19f2b0377","http://resolver.tudelft.nl/uuid:ad66900b-93ea-439b-8a32-d8b19f2b0377","Influences of characteristic size of contact bodies on rolling contact","Qian, Z.; Deng, X.; Li, Z.; Dollevoet, R.P.B.J.","","2014","The rolling contact of elastic bodies (upper body and lower body) can be analyzed with the Hertz theory and the Kalker’s model. It is generally believed that the width of the contact area should be much smaller than the characteristic size of each elastic body, to ensure that the half-space assumption is valid. However the definition of “much smaller” is not that clear. In practice the 3x rule is usually employed, which requires the characteristic size of each elastic body must be at least three times larger than the width of the contact area. This empirical rule is examined in this paper, by looking at the results of the Kalker’s model and of a three-dimensional finite element model to study the influences of lower body width on the rolling contact. It is found that the contact behavior predicted by the Kalker’s model are still acceptable even when the characteristic size of contact bodies is close to the width of the contact area. This finding extends the applicability of classical quasi-static methods to a wider scope, and thus may simplify the calculation procedures for rolling contact problems.","rolling contact; size effects; elastic contact bodies; 3D exolicit FEA; wheel-rail interaction","en","conference paper","University of Zagreb","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:39ee2f7a-7a41-413c-938c-af5a14d3d43f","http://resolver.tudelft.nl/uuid:39ee2f7a-7a41-413c-938c-af5a14d3d43f","Modeling possibilities of concrete structure for durability purposes","Stroeven, P.; He, H.; Le, L.B.N.; Li, K.","","2014","","","en","conference paper","Astroprint","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:02bc7359-7136-4844-8691-f95436e7340c","http://resolver.tudelft.nl/uuid:02bc7359-7136-4844-8691-f95436e7340c","Loop detector data error diagnosing and interpolating with probe vehicle data","Li, J.; Van Zuylen, H.J.; Wei, G.","","2014","Traffic volume and queue length are two important variables to identify traffic states in urban areas. Loop detectors are often used for monitoring traffic. A prominent weakness of loop detector data is the limited reliability due to equipment malfunctions and communication faults. This paper presents a method to identify the validity of loop detector measurements by analyzing the ratio of counts on adjacent lanes. GPS data from probe vehicles are an alternative for monitoring traffic states. They include instantaneous speed, acceleration and position; individual vehicle trajectories can be grossly estimated in real time. Consequently, the queue length can be measured approximately. This can be used to estimate traffic volumes and the percentage of probe vehicles. By combining loop detector and GPS data, more information regarding traffic status can be extracted from both data sources. This paper discusses two methods to check the volume counts and to fill in missing or invalid data: one method uses the ratio of loop detector counts on adjacent links, the other one uses data from probe vehicles to estimate the traffic volumes from the dynamics of the queue length at signalized intersections. Real data from the city Changsha in China are used to validate these two methods. The developed methods provide a way for the online monitoring of detectors’ performance and level of service at signalized intersections","signalized intersection; loop detector; data correction; GPS data; queues","en","conference paper","TRB","","","","","","","","Civil Engineering and Geosciences","Transport and Planning","","","",""
"uuid:43257ed0-54d8-466f-919b-27316003ef9f","http://resolver.tudelft.nl/uuid:43257ed0-54d8-466f-919b-27316003ef9f","Driver behavior at urban roads in China","Li, J.; van Zuylen, H.J.; van der Horst, E.","","2014","Driver behavior in China shows remarkable differences from that in western countries. In this study, six focus groups were organized to investigate Chinese drivers’ attitudes, expectations, intended actions, their preferences, and habits in different situations in urban areas. The outcomes show that there are important opportunities to improve driver behavior, leading to safer and more efficient traffic. Driver behavior–related simulation models have been developed for traffic plan, evaluation and design purpose. Most of these models consider relatively ideal driver behavior in western countries in the – for them common - traffic conditions. This study shows what modifications and calibration are needed to make such models valid for Chinese traffic.","Focus group; Driver behavior; Traffic Offences; Traffic Priority Rules; China","en","conference paper","TRB","","","","","","","","Civil Engineering and Geosciences","Transport & planning","","","",""
"uuid:fd440ca3-06f8-4d40-85ab-92c024ea6fe7","http://resolver.tudelft.nl/uuid:fd440ca3-06f8-4d40-85ab-92c024ea6fe7","The development of area wide traffic management scenarios","Van Zuylen, H.J.; Lu, S.; Li, J.; Yusen, C.","","2014","Traffic management in cities with congestion is a big challenge with still unused opportunities. Intersection control is a corner stone but this should be done in an area-wide context. The dominant traffic process on urban roads is the traffic flow on the intersections. Spill back is a most important cause of malfunctioning networks. The methodology described in this paper gives a structured approach to develop scenarios for dynamic traffic management. The detection of spillback can be done by the analysis of probe vehicle data. Using the conflicts at the intersections as the basic elements of the network capacity analysis and the basis of traffic control, this paper develops a method to define control scenarios by evaluation and adaptation of local traffic control, buffering and metering strategies and rerouting. To support the task of traffic managers, the monitoring, traffic management scenarios and evaluation by simulation are integrated in a decision support system, iTides. This methodology is applied in a network in the CBD of Changsha, the capital of Hunan Province in P.R. China.","spill back; probe vehicles; buffers; rerouting; conflict group; decision support system","en","conference paper","TRB","","","","","","","","Civil Engineering and Geosciences","Transport and Planning","","","",""
"uuid:9afb526b-cd59-4e95-9e0b-7fb8d75da53b","http://resolver.tudelft.nl/uuid:9afb526b-cd59-4e95-9e0b-7fb8d75da53b","Numerical simulation of impact noise generated at the railway insulated joint","Yang, Z. (TU Delft Railway Engineering); Rahimi, S. (TU Delft Railway Engineering); Li, Z. (TU Delft Railway Engineering); Dollevoet, R.P.B.J. (TU Delft Railway Engineering)","Sas, P (editor); Denayer, H (editor); Moens, D (editor)","2014","This paper presents a full finite element (FE) model of wheel-track interaction to study the wheel-rail impact noise excited by an insulated joint (IJ). The integration is performed in the time domain with an explicit central difference scheme. The vibratory behaviour of the track and wheel model are respectively validated with hammer test and Axle Box Acceleration (ABA) measurement. By making use of the calculated velocities and pressures on the vibrating surfaces, the boundary element method (BEM) based on Helmholtz equation is adopted to transform the vibrations of the wheel-track into acoustic signals. The decay rate of impact noise at different frequency bands during propagation are analysed. The predictions of total impact noise radiation and the noise contributions of different track components are in good agreement with results reported in the literature, while the effective frequency range is successfully extended from 5 kHz to 10 kHz.","Conf.proc. > 3 pag","en","conference paper","Katholieke Universiteit Leuven Department of Mechanical Engineering","","","","","Accepted Author Manuscript","","","","","Railway Engineering","","",""
"uuid:f7c83a60-8922-4e6d-860d-0bdcb10e3a6b","http://resolver.tudelft.nl/uuid:f7c83a60-8922-4e6d-860d-0bdcb10e3a6b","Macroscopic travel time reliability diagrams for freeway networks","Tu, H.; Li, H.; Van Lint, J.W.C.; Knoop, V.L.; Sun, L.","","2013","Travel time reliability is considered to be one of the key indicators of transport system performance. Knowledge of the mechanisms of travel time unreliability enables the derivation of explanatory models with which travel time reliability can be predicted and utilized in traffic management. Inspired by the macroscopic fundamental diagram (MFD), describing the relationship between production (average flow completing the trips) and vehicle accumulation (average density) in a traffic network, this paper investigates a macroscopic travel time reliability diagram (MRD) relating the travel time reliability to the network accumulation. The MFD relationship has potential because it characterizes the state of an entire traffic network with just two (production and accumulation) or three (adding spatial variability of accumulation) state variables. Likewise, the MRD describes the network travel time reliability as a function of just one independent state variable (network accumulation). Empirical analyses were performed to investigate the variability in MFD as seen in scatters and to show the travel time reliability in relation to the network accumulations. Traffic data from Dutch freeway networks were employed to facilitate the analyses. With the MRD for different freeway networks, it was found that a critical travel time reliability accumulation existed, below which network accumulation had little or no impact on travel time reliability and above which it had a significant impact. Also, the critical travel time reliability accumulation was, in general, lower than the critical MFD accumulation. These findings provide insights for road authorities in how to make trade-offs in traffic management between maximum production and travel time reliability.","","en","conference paper","Transportation Research Board","","","","","","","","Civil Engineering and Geosciences","Transport and Planning","","","",""
"uuid:ada7aea0-701e-40fc-a585-5640a30d2749","http://resolver.tudelft.nl/uuid:ada7aea0-701e-40fc-a585-5640a30d2749","Designing for crowd well-being: Current designs, strategies and future design suggestions","Li, J.; de Ridder, H.; Vermeeren, A.P.O.S.; Conrado, C.; Martella, C.","","2013","This paper introduces the concept of crowd well-being and the needs for sustaining it. Crowd well-being can be interpreted as crowd members’ evaluations on their emotional reactions, moods and judgments they form about their satisfactions, goals or needs fulfillment in a crowded situation according to the definition of subjective well-being by Diener and his colleagues. Higher level needs, i.e. relatedness and autonomy in Sheldon’s two-level hierarchy are essential to the enhancement of crowd well-being when safety is guaranteed. Needs for safety become prominent in case of emergencies. Furthermore, it investigates three representative crowd management designs and strategies and how they fulfill the needs of crowd members through ten crowd expert interviews. We conclude that the current strategies and designs mostly focus on the effortful planning and preparation for the potentially unsafe situations, which tend to be coercive instead of fully respect crowd members’ autonomy. A number of technologies are applied to monitor the crowd behaviors externally due to the security concerns rather than approach and assess them locally, understand their needs and provide real-time feedbacks to support their well-being. We suggest that future designs should allow the measuring to go into the crowds and place an emphasis on improving crowd members’ higher level needs on the premise of security.","crowd well-being; crowd management strategies; design for crowd","en","conference paper","International Association of Societies of Design Research","","","","","","","","Industrial Design Engineering","Industrial Design","","","",""
"uuid:adf3122e-503b-485d-83bf-64d2611c4845","http://resolver.tudelft.nl/uuid:adf3122e-503b-485d-83bf-64d2611c4845","GNSS integer ambiguity estimation and evaluation: LAMBDA and Ps-LAMBDA","Li, B.; Verhagen, A.A.; Teunissen, P.J.G.","","2013","Successful integer carrier-phase ambiguity resolution is crucial for high precision GNSS applications. It includes both integer estimation and evaluation. For integer estimation, the LAMBDA method has been applied in a wide variety of GNSS applications. The method’s popularity stems from its numerical efficien-cy and statistical optimality. However, before conducting ambiguity resolution, one needs to infer how reliable the fixed solution can expected to be, as incorrect fixed ambiguity solutions often lead to unacceptable positioning errors. In this pa-per, two Matlab software tools are introduced for the evaluation and integer esti-mation: Ps-LAMBDA and an updated version of LAMBDA. Evaluation of the in-teger solution is based on the ambiguity success rate. Since this probability of correct integer estimation is generally difficult to compute, easy-to-use approxi-mations and bounds of the ambiguity success rate are provided by the Ps-LAMBDA software. This success rate tool is valuable not only for inferring whether to fix the ambiguities but also for design and research purposes. For the actual integer estimation, the updated version of the LAMBDA software, provides now more options of integer estimation and integer search, including the search-and-shrink strategy. In addition, the Fixed Failure-rate Ratio Test (FF-RT) and the Fixed Critical-value Ratio Test (FC-RT) are incorporated for users to validate the significance of the fixed solution. Using these two software tools together allows for the combined execution of integer estimation and evaluation, thus benefiting multi-frequency, multi-GNSS applications.","LAMBDA; Ps-LAMBDA; integer rounding; integer bootstrapping; integer least-squares; search-and-shrink; ambiguity success rate; ambiguity resolution","en","conference paper","Springer","","","","","","","","Civil Engineering and Geosciences","Geoscience & Remote Sensing","","","",""
"uuid:089a2ea0-e77e-4da8-bffc-b2e404cee139","http://resolver.tudelft.nl/uuid:089a2ea0-e77e-4da8-bffc-b2e404cee139","A field study on real-time self-reported emotions in crowds","Li, J.; Erkin, Z.; De Ridder, H.; Vermeeren, A.P.O.S.","","2013","Crowd experience is inevitable in daily life. Crowd managers need tools to accurately estimate the psychological aspects of crowds, an important one being crowd emotion. In this study, we explore the feasibility of obtaining a real-time, dynamic map of crowd emotions through self-reporting by crowd members. To this end, a smart phone application “EmoApp” was developed. EmoApp allows users to report their emotions without interfering with their on-going activities. We conducted a field study to test EmoApp in a music festival. The collected data revealed that the users’ movements and emotional changes were consistent with the activities at the festival. This suggests that a majority of the users reported their real emotions. The paper also discussed several aspects of emotion detection, namely, privacy protection, reliability of self-report method, accuracy of positioning users and user-friendliness of the application design. This study is part of the on-going research in understanding the psychological aspects of crowds.","Crowd emotion; crowd management; real-time emotion; self-reported emotion","en","conference paper","STW - IPN","","","","","","","","Industrial Design Engineering","Industrial Design","","","",""
"uuid:d9bf525d-7984-49fb-a848-10151be8a474","http://resolver.tudelft.nl/uuid:d9bf525d-7984-49fb-a848-10151be8a474","C-S-H globule clustering on nano-scale simulated by the discrete element method for pore structure exploration","Li, K.; Stroeven, M.; Stroeven, P.; Sluys, L.J.","","2013","","","en","conference paper","Rilem","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:4855569b-e4aa-400f-9f7b-c617daeeedf7","http://resolver.tudelft.nl/uuid:4855569b-e4aa-400f-9f7b-c617daeeedf7","Strategy for exploring the pore structure of cementitious materials based on a DEM approach (poster)","Li, K.; Stroeven, M.; Stroeven, P.; Sluys, L.J.","","2013","","","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:17530165-6501-4dbd-82a0-64a12f1f5f64","http://resolver.tudelft.nl/uuid:17530165-6501-4dbd-82a0-64a12f1f5f64","An explicit integration finite element method for impact noise generation at squat","Yang, Z.; Li, Z.; Dollevoet, R.P.B.J.","","2013","This paper presents a full finite element (FE) interaction model of wheel-track to study the wheel-rail impact noise caused by squat. The wheel, the rail and some other track components are modeled with finite elements in three dimensions, where necessary and appropriate. Realistic contact geometry, including geometric irregularity (squat) in the contact surfaces is considered. The integration is performed in the time domain with an explicit central difference scheme. For convergence, the Courant time step condition is enforced, which, together with the detailed modeling of the structural and continuum of the wheel-track system, effectively guarantees that vibration frequency of 10 kHz or higher is reproduced. By making use of the calculated velocities and pressures on the vibrating surfaces, the boundary element method (BEM) based on Helmholtz equation is adopted to transform the vibration of the track into acoustic signal.","","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:b22ce8c6-7955-49b7-9d64-f0f09bac1c13","http://resolver.tudelft.nl/uuid:b22ce8c6-7955-49b7-9d64-f0f09bac1c13","Oxidation induced crack healing of Cr2(Al,Si)C max phase ceramic","Shen, L.; Li, S.B.; Van der Zwaag, S.; Sloof, W.G.","","2013","The oxidation crack healing of Cr2AlC and Cr2(Al,Si)C was studied and compared with known healing of Ti2AlC. The oxidation induced crack healing of Ti2AlC is relatively fast and leads to full strength recovery, but the oxidation product contains besides ?-Al2O3 also undesired TiO2. However, when oxidizing Cr2AlC only ?-Al2O3 is formed, but full crack healing is relatively slow. The efficiency of the oxidation induced crack healing of Cr2AlC is enhanced if Al is partially replaced by Si atoms.","Cr2AlC; Cr2(AlSi)C; crack healing; oxidation kinetics; microstructure analysis","en","conference paper","Magnel Laboratory for Concrete Research","","","","","","","","Mechanical, Maritime and Materials Engineering","Materials Science and Engineering","","","",""
"uuid:bc6adf64-b2c4-4801-8897-427de21681d8","http://resolver.tudelft.nl/uuid:bc6adf64-b2c4-4801-8897-427de21681d8","Relative role of bed roughness, bed erosion and channel storage on peak discharge increase in hyperconcentrated floods (abstract)","Li, W.; Wang, Z.B.; Van Maren, D.S.; De Vriend, H.J.; Wu, B.S.","","2013","","","en","conference paper","IAHR","","","","","","","","Civil Engineering and Geosciences","Hydraulic Engineering","","","",""
"uuid:8fae0d69-aa2a-4dc9-ac87-8aec81be5d69","http://resolver.tudelft.nl/uuid:8fae0d69-aa2a-4dc9-ac87-8aec81be5d69","Designing for crowd well-being: Needs and design suggestions","Li, J.; De Ridder, H.; Vermeeren, A.P.O.S.; Conrado, C.; Martella, C.","","2013","This paper investigates the needs or criteria for sustaining well-being in crowded situations through two focus group discussions with a total of ten participants. We conclude that pursuing crowd well-being could be divided into two different cases: one is obtaining the enhancement of the current state in normal situations, and the other is avoiding the deficiencies in case of emergencies. The psychological needs are different in these two cases. Crowd members pay attention to higher level of psychological needs, i.e. staying autonomic, connected, competent and respected in the former situation, while their focus will immediately change to low level needs, i.e. safety and security issues, when unexpected things happen. These findings are consistent with Sheldon et al.’s new hierarchy of needs. We also find that all the crowd types mentioned in the focus group discussions could be classified into two categories, namely event crowds and non-event crowds. A crowd can also consist of both event moments (e.g. watching performances or dancing with the crowds) and non-event moments (e.g. waiting in queues). The event crowds are looking for enhancement of their experiences in the crowds, whose needs are usually higher level, whereas the non-event crowds usually cannot help joining the crowds in order to achieve their goals. The event moments when the higher level needs is fulfilled are usually associated with positive moments. The non-event moments when only security is promised and have no support on higher level needs are usually associated with negative moments. To get insights into how crowd well-being is currently fulfilled by crowd management strategies and designs, we investigated a number of influential crowd management literatures. The results reveal that emphasis is placed on supporting the safety. Most strategies focus on preparation and prediction instead sustaining real-time crowd well-being. Most of the designs tend to be coercive instead of respecting the autonomy. In conclusion, designing for crowd well-being could change towards the real-time and aim at fulfilling the higher needs, i.e. autonomy, competence, self-esteem and relatedness on the premise of security.","human-centered design; crowd well-being; hierarchy of needs; crowd types","en","conference paper","National Cheng Kung University","","","","","","","","Industrial Design Engineering","Industrial Design","","","",""
"uuid:113ca57b-fdb0-4e4e-b25d-535699b3ecad","http://resolver.tudelft.nl/uuid:113ca57b-fdb0-4e4e-b25d-535699b3ecad","Contextualized institutions in virtual organizations","Li, T.; Jiang, J.; Aldewereld, H.M.; de Vos, M.; Dignum, V.; Padget, J.A.","","2013","Within a virtual organization, more than one institution might be involved in the regulation of actors’ behavior. Each institution specifies a set of norms covering a specific aspect of the problem domain with a governance scope defining its remit. Together, they govern the participants and reflect the objectives of the organization. With actors’ behavior being simultaneously regulated by more than one institution, normative conflicts can appear. In this paper, we formalize the notion of governance scope and propose a computational approach to identify weak and strong norm conflicts in virtual organizations. This is achieved by explicitly modeling the governance scopes of institutions through context models. We illustrate our approach by means of a case study concerning food security in international trade.","","en","conference paper","","","","","","","","","Technology, Policy and Management","Engineering Systems and Services","","","",""
"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:b50d1472-7829-4099-89d9-3d06d82d1133","http://resolver.tudelft.nl/uuid:b50d1472-7829-4099-89d9-3d06d82d1133","Analysis of five-point bending test for multilayer surfacing system on orthotropic steel bridge","Li, J.; Scarpas, A.; Tzimiris, G.; Kasbergen, C.; Hofman, R.; Voskuilen, J.","","2013","The French five-point bending test (5PBT) provides a laboratory scale test that allows studying the fatigue resistance of surfacing systems on orthotropic steel deck bridges (OSDB). The surfacing structure for OSDB in the Netherlands consists mostly of multilayer system: top porous asphalt layer, guss asphalt layer, steel deck and two membrane layers. In this paper, an analytical solution for 5PBT setup is presented first. In order to better understand the influence of geometrical, mechanical and structural parameters on the performance of the typical multilayer surfacing system of OSDB in the Netherlands, the 5PBT specimens with five structural layers have been investigated. The parametric study is performed at the numerical platform CAPA-3D that was developed at the Section of Structural Mechanics of TU Delft. The thicknesses of the top porous asphalt layer, middle guss asphalt layer and the steel plate are varied. The influences of the mechanical properties of both top and bottom membrane layers are studied. The sensitivities of those influence factors are evaluated by the examination of the maximum tensile stress at the top surface of the porous asphalt layers and the strain distributions through the entire thickness of the specimen at two cross sections.","five-point bending test, orthotropic steel deck bridge, surfacings, membrane, finite element analysis","en","conference paper","Transportation Research Board","","","","","","","","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: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:34171d01-4bf1-4c11-bbf6-630bd2adb491","http://resolver.tudelft.nl/uuid:34171d01-4bf1-4c11-bbf6-630bd2adb491","An investigation into the relation between wheel/rail contact and bolt tightness of rail joints using a dynamic finite element model","Oregui, M.; Li, Z.; Dollevoet, R.P.B.J.","","2012","Rail joints have a shorter service life than most other railway track components. The discontinuity between rail ends turns the rail joint into a weak spot, and consequently, into a track component demanding more frequent maintenance measures, which result in high maintenance costs. Moreover, difficulties are often found when assessing the damage condition of rail joints since damage conditions like cracks in the rail web or loose bolts cannot be detected by visual inspection. A better understanding of the damage mechanisms and degradation process of rail joints may help to develop adapted maintenance measures and to improve rail joint design. In this paper, a 3D Finite Element model is presented as base for rail joint study. The model represents accurately the main components (rail, sleeper, joint bars and wheel) and the interaction between them (contact). The model is validated between 150 and 800 Hz with measured axle box accelerations of resilient wheels. Higher frequencies may be reached with an improved model of the rubber. In the paper, the influence of the bolt tightness is studied. The results showed that contact force, specially its variation, is strongly affected by the bolt tightness; loose bolts cause higher contact forces. The effect of vehicle speed on wheel/rail contact is also significant mainly due to the interaction between rail and sleepers in the vicinity of the rail joint. Apart from bolt tightness conditions and vehicle speed, the validated model has the potential to study the influence of other track parameters and damage conditions","","en","conference paper","Southwest Jiaotong University","","","","","","","","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:b09b2ec3-62ee-479c-8c3d-6d24c2b77da0","http://resolver.tudelft.nl/uuid:b09b2ec3-62ee-479c-8c3d-6d24c2b77da0","3D cadastre in China: A case study in Shenzhen City","Guo, R.; Li, L.; He, B.; Luo, P.; Ying, S.; Zhao, Z.; Jiang, R.","","2011","","land administration; land use; cadastre; three dimensions","en","conference paper","International Federation of Surveyors (FIG)","","","","","","","","OTB Research Institute for the Built Environment","","","","",""
"uuid:3320544f-f6d8-4c07-8750-86d106419e5e","http://resolver.tudelft.nl/uuid:3320544f-f6d8-4c07-8750-86d106419e5e","Design and development of a 3D cadastral prototype based on the LADM and 3D topology","Ying, S.; Guo, R.; Li, L.; Van Oosterom, P.J.M.; Ledoux, H.; Stoter, J.E.","","2011","In this paper the design and development of a prototype 3D Cadastral system will be presented. The key aspects of this system are that the model is based on Land Administration Domain Model (LADM) and that the spatial profile is based on a full 3D topological structure. The prototype development starts with profiling the LADM (selecting relevant model classes and extending the model with attributes and classes where needed). The LADM supports various options for representing spatial units (parcels); e.g. a 2D parcel or a 3D volume. 2D parcel is well-known, however, how to create and maintain 3D valid parcels is still a challenge in practice. The 3D topology structure uses the well-known primitives node (0D), edge (1D), face (2D) to construct body (3D), which represent a spatial occupation of 3D parcel. Geometry is only explicitly stored at the nodes. A 3D Cadastre topology is realized using the API of Google SkecthUp. Details of geometric and topological aspects of the model are specified in the paper. 3D data (collection of faces) initially created by other tools or software can be loaded in prototype and then valid 3D solids /bodies of cadastral parcel volumes can be constructed and stored into the database. Of course, each 3D cadastral object and its intermediate neighbourhood can be retrieved from the database to be edited. During the editing, certain geometric changes need topological reconstruction before the updated data is loaded back into the database. Also other applications, non 3D-topology-aware, can connect to this database populated with 3D topologically structured parcel data; e.g. a 3D web-viewer, or a 3D analysis application like Skyline and Google Earth. The developed system is currently limited to represent closed solid/bodies. The purpose of this paper is to illustrate the feasibility a 3D topology based implementation of LADM by developing a prototype (tools), loading real world data and to implement construction of the 3D parcels.","3D parcel; topology; solid","en","conference paper","International Federation of Surveyors (FIG), EuroSDR, TUDelft","","","","","","","","OTB Research Institute for the Built Environment","OTB Research","","","",""
"uuid:da280062-b4b0-490c-9f4a-281f6e40225d","http://resolver.tudelft.nl/uuid:da280062-b4b0-490c-9f4a-281f6e40225d","A multi-jurisdiction case study of 3D cadastre in Shenzhen, China as experiment using the LADM","Guo, R.; Ying, S.; Li, L.; Luo, P.; Van Oosterom, P.J.M.","","2011","","3D cadastre; land administration model; jurisdiction","en","conference paper","International Federation of Surveyors (FIG)","","","","","","","","OTB Research Institute for the Built Environment","OTB Research","","","",""
"uuid:075deb5b-5253-4daf-97be-f7126519612b","http://resolver.tudelft.nl/uuid:075deb5b-5253-4daf-97be-f7126519612b","GNSS ambiguity resolution: Which subset to fix?","Verhagen, A.A.; Teunissen, P.J.G.; Van der Marel, H.; Li, B.","","2011","A key issue with GNSS carrier phase ambiguity resolution is that often the full set of ambiguities cannot be fixed fast and reliably. A possible strategy is then to resolve only a subset of ambiguities, one for which the probability of correct fixing, the so-called success rate, is sufficiently close to 1. However, a proper subset selection criterion is still lacking. This criterion should on the one hand guarantee an acceptably high success rate, and at the same time result in a significant performance improvement with respect to the remaining parameters, like the baseline parameters. The second requirement is important and has not yet been addressed in literature. As an extreme example consider the case where the float ambiguities are not correlated with the other float parameters. Ambiguity resolution would then be useless, since it will then not allow for an improvement of these other parameters. This indicates that resolving a subset of ambiguities (in the extreme example, an empty subset) may lead to the same, or almost same, performance improvement of the other parameters, notably the baseline solution. This contribution presents two approaches to subset selection, where both the requirements on success rate and performance improvement are taken into account. With this approach the user can set a threshold for the success rate to be obtained. It will be shown how much better the baseline solution will be after reliable fixing of the subset of ambiguities.","partial ambiguity resolution; success rate; precision and reliability","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Geoscience & Remote Sensing","","","",""
"uuid:35f134ec-de40-4922-a376-a6aeae4f3203","http://resolver.tudelft.nl/uuid:35f134ec-de40-4922-a376-a6aeae4f3203","Contextualized Institutions in Virtual Organizations (abstract)","Li, T.; Jiang, J.; Aldewereld, H.M.; De Vos, M.; Dignum, M.V.; Padget, J.","","2011","","","en","conference paper","","","","","","","","","Technology, Policy and Management","Infrastructures, Systems and Services","","","",""
"uuid:fa4cce21-1e8e-450b-a3c7-f82d4ffa4fa4","http://resolver.tudelft.nl/uuid:fa4cce21-1e8e-450b-a3c7-f82d4ffa4fa4","Compact collimators for high brightness blue LEDs using dielectric multilayers","Cornelissen, H.J.; Ma, H.; Ho, C.; Li, M.; Mu, C.","","2011","A novel method is presented to inject the light of millimeter-sized high-brightness blue LEDs into light guides of submillimeter thickness. Use is made of an interference filter that is designed to pass only those modes that will propagate in the light guide by total internal reflection. Other modes are reflected back to the LED cavity and recycled, leading to an increased brightness. With this method a collimator has been designed and made that is only 1mm thick, with a diameter of 6.5mm. It creates a beam of 26deg Full Width at Half Maximum. Presently, collimators with these characteristics have a thickness of 10-20mm and a diameter of 20-30mm and require careful mounting and alignment. The new collimator contains a 4.5micron thick interference filter made of 54 layers of Nb2O5 and SiO2 layers. The filter is optically coupled to the LED with Silicone adhesive which makes the configuration very robust. A cylindrical lightguide, tapered from 6.5mm to 2.5mm diameter and 1mm thick captures the light that passes the filter, folds the light path and redirects the beam. Measurements on collimator prototypes show good agreement with the designed characteristics. This promising approach enables much more compact collimators optics that offer material cost savings and design freedom.","thin-film interference filter; dielectric multilayer; LED; collimator; Total Internal Reflection; light guide","en","conference paper","SPIE","","","","","","","","Applied Sciences","Optics Research Group","","","",""
"uuid:36d320eb-e9ee-4a29-bb2a-d4be70418460","http://resolver.tudelft.nl/uuid:36d320eb-e9ee-4a29-bb2a-d4be70418460","Crack healing behaviour of a Cr2AlC ceramic (abstract)","Li, S.B.; Xiao, L.O.; Song, G.M.; Wu, X.M.; Sloof, W.G.; Van der Zwaag, S.","","2011","","crack-healing; Cr2AlC; mechanical property; healing mechanism; microstructure","en","conference paper","","","","","","","","","Delft University of Technology","","","","",""
"uuid:bd28fb21-9f24-4141-a418-d688ff7315b3","http://resolver.tudelft.nl/uuid:bd28fb21-9f24-4141-a418-d688ff7315b3","Multiple crack-healing and strenght recovery in MAX phase ceramics (abstract)","Sloof, W.G.; Li, S.; Song, G.; Kwakernaak, C.; Wu, X.; Van der Zwaag, S.","","2011","","self-healing; MAX phase ceramics; mechanical testing; multiple crack healing","en","conference paper","","","","","","","","","Delft University of Technology","","","","",""
"uuid:bd8eb934-510f-49da-8ad9-c44705696767","http://resolver.tudelft.nl/uuid:bd8eb934-510f-49da-8ad9-c44705696767","Modeling oxidation induced crack healing in non-oxide ceramics and metallo-ceramics (abstract)","Song, G.M.; Li, S.B.; Sloof, W.G.; Van der Zwaag, S.","","2011","","self-healing; ceramics; oxidation; modeling; strength recovery","en","conference paper","","","","","","","","","Delft University of Technology","","","","",""
"uuid:97ea4579-edb9-41e9-96eb-153eec7d6691","http://resolver.tudelft.nl/uuid:97ea4579-edb9-41e9-96eb-153eec7d6691","A 3D finite element modeling of hammer test for track parameter identification","Oregui, M.; Li, Z.; Dollevoet, R.P.B.J.; Moraal, J.","","2011","In railway tracks, short wave rail surface defects give rise to high wheel-rail dynamic forces and noise. Having a better insight into short wave defect occurrence could lead to development of adapted maintenance methods or track design to delay or avoid defect, so that the high short wave defect related maintenance costs may be reduced. As part of a health monitoring method under development, obtaining track dynamic characteristics is the first step in assessing track deterioration. In-situ hammer test measurements are widely used for track parameter derivation. In this paper, in order to reproduce hammer test measurements so that track parameters can be identified, a Finite Element model was developed where the rail and the sleeper were modeled with their real geometry. Although some discrepancy still exists between the first and second order pin-pin anti-resonances and the measured frequencies, the model showed the same main track characteristics in the receptance function as the measurements. The reacceptance function in the frequency range 1500-3000 Hz was also qualitatively determined. The model could not yet simulate the frequency response between 450-1000 Hz for tracks with monoblock and timber sleepers as modal analysis of the sleeper corroborated. Future work is focused on improving the model so that it is valid for the complete frequency range of 450-3000 Hz and tracks of all the sleepers type.","hammer test; track vertical dynamics; FE model; parameter identification","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:982672e7-ddec-4e98-b22f-21cbbf6d5444","http://resolver.tudelft.nl/uuid:982672e7-ddec-4e98-b22f-21cbbf6d5444","Relating tensile properties with flexural properties in SHCC","Qian, S.; Li, V.C.; Zhou, J.","","2010","Strain hardening cementitious composites (SHCCs) have seen increasing field applications in past decade, yet existing quality control test methods for tensile properties are sometime difficult to implement. This paper presents a new simple inverse method for quality control of tensile strain capacity by conducting beam flexural test. It is shown through a theoretical model that the beam deflection from a flexural test can be linearly related to tensile strain capacity. A master curve relating this easily measured structural element property to material tensile strain capacity is constructed from parametric studies of a wide range of material tensile and compressive properties. This proposed method (UM method) has been validated with uniaxial tensile test results with reasonable agreement. Good agreement between prediction and tensile test suggest that this method is very robust for different mixtures with variable geometry and test setup.","","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Structural Engineering","","","",""
"uuid:73c3c8c8-b479-4754-932a-da76ccdc374b","http://resolver.tudelft.nl/uuid:73c3c8c8-b479-4754-932a-da76ccdc374b","Modeling Departure Time Choice with Stochastic Networks","Li, H.; Bliemer, M.C.J.; Bovy, P.H.L.","","2010","Stochastic supply and fluctuating travel demand lead to stochasticity in travel times and travel costs experienced by travelers from time to time within a day and at the same time from day to day. Many studies show that travel time un-reliability has significant impacts on traveler’s choice behavior under uncertainty. Different theories are applicable to describe and model traveler’s choice behavior under uncertainty. This paper presents several behavioral models based on differ-ent behavioral hypotheses under uncertainty in the framework of utility theory. An analytical approach is employed to investigate the generality and the relationships among the different behavioral models for modeling traveler’s route/departure time choice behaviors under uncertainty. This paper shows the principal equiva-lence of different behavioral models and the condition at which the equivalence is maintained. The parameters of the utility components are explored with a theoreti-cal approach and a simulation-based approach. This paper explores which utility components should be incorporated in the behavioral model, which has substantial meaning for the researchers and practitioners to gain insights into the relationships of different behavioral models for modeling traveler’s choice behavior under un-certainty. It is concluded that the mean variance approach is a special case of the scheduling approach and of the generalized utility approach. The generalized utili-ty approach is equivalent to the scheduling approach under a certain condition.","","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Transport and Planning","","","",""
"uuid:97a330d0-fd8e-4a53-b316-47a5685f73e7","http://resolver.tudelft.nl/uuid:97a330d0-fd8e-4a53-b316-47a5685f73e7","An investigation on the desired properties of friction modifiers for slippery rails","Li, Z.; Arias Cuevas, O.","","2009","The adhesion level between wheel and rail has been since the beginning of railway a crucial parameter in the design and operation of rail vehicles. In the last decades, many railway organizations have suffered from low adhesion problems as consequence of the increased exploitation of the rail infrastructure. Leaves and water have been widely reported as major causes of low adhesion. Among the practical measures adopted, friction modification is one of the most popular used to enhance adhesion levels to the required minimum during traction and braking. In this paper, some results of investigations carried out with two friction modifiers are presented. Further, some of the desired properties of the friction modifiers to optimally overcome the slippery rails problem are discussed.","","en","conference paper","Japan Society of Mechanical Engineers, JSME, Transportation and Logistics Division","","","","","","","","Civil Engineering and Geosciences","Road and Railway Engineering","","","",""
"uuid:840580aa-0203-4248-bd0f-76fb2e3292f9","http://resolver.tudelft.nl/uuid:840580aa-0203-4248-bd0f-76fb2e3292f9","Experimental study on human experience of complexity in supervision control","Li, K.; Wieringa, P.A.","","1997","","","en","conference paper","University of Kassel - GhK","","","","","","","","Mechanical Maritime and Materials Engineering","","","","",""
"uuid:055f7afd-22bf-4bc5-b841-dddf31b66217","http://resolver.tudelft.nl/uuid:055f7afd-22bf-4bc5-b841-dddf31b66217","Degree and Principal Eigenvectors in Complex Networks","Li, C.; Wang, H.; Van Mieghem, P.","","","The largest eigenvalue ? 1 of the adjacency matrix powerfully characterizes dynamic processes on networks, such as virus spread and synchronization. The minimization of the spectral radius by removing a set of links (or nodes) has been shown to be an NP-complete problem. So far, the best heuristic strategy is to remove links/nodes based on the principal eigenvector corresponding to the largest eigenvalue ? 1. This motivates us to investigate properties of the principal eigenvector x 1 and its relation with the degree vector. (a) We illustrate and explain why the average E[x 1] decreases with the linear degree correlation coefficient ? D in a network with a given degree vector; (b) The difference between the principal eigenvector and the scaled degree vector is proved to be the smallest, when ?1=N2N1 , where N k is the total number walks in the network with k hops; (c) The correlation between the principal eigenvector and the degree vector decreases when the degree correlation ? D is decreased.","networks; spectral radius; principal eigenvector; degree; as-sortativity","en","conference paper","Springer","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Network Architectures and Services Group (NAS)","","","",""