"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:09a0ef1d-9c35-4817-b515-e025a9ab837f","http://resolver.tudelft.nl/uuid:09a0ef1d-9c35-4817-b515-e025a9ab837f","Design for Togetherness at Home: Integrating Technology to Bond Children and Grandparents Through Shared Experiences","Xu, Hongxin (TU Delft Industrial Design Engineering)","van der Vegte, Wilhelm Frederik (mentor); Gielen, M.A. (mentor); Delft University of Technology (degree granting institution)","2024","Strong intergenerational relationships can provide emotional support and stability for both grandparents and grandchildren. Technology tools have been proven to be beneficial in connecting grandchildren and grandparents. Prior work mainly examined how to use technology to connect children and their grandparents over a distance. Those collocated grandparents and grandchildren who keep regular physical contact are often neglected in the research.It is essential to understand technology’s potential in bonding them in physical meet ups considering the trending of multigenerational families.
This graduation project aims to foster connectedness between children aged 8 to 12 and their collocated grandparents in the Netherlands through physical interactions. Adopting a holistic approach, we explored moments of togetherness, identifying desired qualities of these interactions and defining promising shared experiences for the future.
The research involves three phases of empirical investigations. This research begins by examining how technology could positively impact their bond. Using participatory cards during interviews, this phase captures participants' perspectives, employing mixed methods including sentiment analysis, group clustering, and thematic coding to identify key elements in shared activities that promote or impede intergenerational connectivity. This analysis informs a framework to guide the development of technology aimed at supporting connectivity. Next, the second phase, insights from two design workshops are synthesized into a series of design concepts, which are then visualized through storyboards. The final phase involves evaluating these concepts by presenting the storyboards to both experts and child-grandparent pairs. This step is intended to refine our understanding of how these technological solutions can be leveraged to strengthen family bonds.","Intergenerational Relationships; Child-Grandparent Connection; Technology in Family Bonding; Design and Family Dynamics","en","master thesis","","","","","","","","","","","","Design for Interaction","",""
"uuid:7defbd1e-dcbd-421e-aba5-2a58009a1329","http://resolver.tudelft.nl/uuid:7defbd1e-dcbd-421e-aba5-2a58009a1329","Towards a transition territory: Planning and design strategies to improve social and ecological conditions in the peri-urban area of Shanghai","Xu, Shiming (TU Delft Architecture and the Built Environment)","Furlan, C. (mentor); Qu, L. (graduation committee); Nottrot, R.J. (graduation committee); Delft University of Technology (degree granting institution)","2024","Shanghai has experienced rapid urbanization over the past 30 years, with a large number of rural areas being transformed into semi-urbanized areas with mixed functions. The main drivers were top-down state-led development, market forces, and bottom-up rural industrialization. The scale and speed of this process have far exceeded expectations, leading to a series of socio-ecological problems such as population loss, industrial decline, and environmental pollution. Based on the analysis, this dissertation identifies two development directions: industrial restructuring and ecological protection, to cope with the uncertainty of population growth, a scenario-building approach is used to explore the optimal strategies under different circumstances. Design strategies are extracted through scenario evaluation and applied to strategic planning.","peri-urban areas; scenario building; urban design; Shanghai","en","master thesis","","","","","","","","","","","","Architecture, Urbanism and Building Sciences | Urbanism","",""
"uuid:537f10c1-45bc-4303-a777-ecbad5b070cd","http://resolver.tudelft.nl/uuid:537f10c1-45bc-4303-a777-ecbad5b070cd","Exploring Sustainability Considerations in Construction Project Manager Decision-Making In China: An Investigation Using The Q Methodology","Xu, Xiaoyang (TU Delft Civil Engineering & Geosciences)","Straub, A. (graduation committee); Ninan, Dr Johan (mentor); de Bruijne, M.L.C. (mentor); Delft University of Technology (degree granting institution)","2023","This research examines how construction project managers in China integrate sustainability into their decision-making processes despite other constraints, such as cost, time, and quality. Using a Q-methodology, the study reveals a variety of managers' perspectives and strategies on sustainability, highlighting the complexity of integrating sustainability into construction project management.
The study identified three main perspectives of construction project managers: Cost and Sustainability, People and Sustainability, Cost and Quality. The study found that in current practice there is a general preference for safety over sustainability, while there are different perspectives on the sustainability compatibility with project objectives. The study highlights the need for continuous innovation and adaptation in incorporating sustainability while recognizing the diversity of management approaches and the multifaceted nature of construction projects.
While providing practical insights for industry practitioners, the study also recognizes limitations due to data subjectivity, regional differences, and changing external conditions. It is recommended that future research be conducted to compare sustainability integration in different countries and to explore the impact of cultural, economic, regulatory, and environmental factors on sustainable construction practices.","Sustainability; Construction project; Q method; Project management","en","master thesis","","","","","","","","","","","","Civil Engineering | Construction Management and Engineering","",""
"uuid:20fc9968-890b-4d36-a59e-c05bd474d4aa","http://resolver.tudelft.nl/uuid:20fc9968-890b-4d36-a59e-c05bd474d4aa","Integrate and store 3D roads and terrain for navigation purposes","MOUZAKIDIS, DIMITRIOS (TU Delft Architecture and the Built Environment); Puti Nabila Riyadi, Puti (TU Delft Architecture and the Built Environment); Nestoras, Konstantinos (TU Delft Architecture and the Built Environment); Xu, Leon (TU Delft Architecture and the Built Environment); Liu, Na (TU Delft Architecture and the Built Environment); Köbben, Stein (TU Delft Architecture and the Built Environment)","Arroyo Ohori, G.A.K. (mentor); Vitalis, S. (mentor); Stoter, J.E. (mentor); Delft University of Technology (degree granting institution)","2023","Modern navigation heavily relies on Global Navigation Satellite Systems (GNSS) and digitized road network databases, but faces limitations in GNSS-denied areas and complex 2D road netowrks. This project addresses these challenges by developing a methodology to create and store a comprehensive 3D road and terrain dataset for enhanced navigation. In collaboration with TomTom, a company that aims to fulfill software requirements, making significant advancements in geolocation technology and societal contributions. The main research question of the project is: ”How can we create a 3D map of roads using information about the center of the road and elevation data?”. The approach to answer this question involves extracting 2D road polygons from centerline data based on width of the roads, the direction and the amount of lanes of them. These 2D polygons undergo enrichment with elevation data, with techniques like filtering, segmentation, and primitive extraction ensuring alignment with the digital terrain model. The methodology encompasses data acquistion, creation of polygons using the centerlines dataset, 2D-to-3D polygon conversion, elevation integration and data storage in CityJSON format.","3D roads; Navigation; Elevation integration; Centerlines; Polygons","en","student report","","","","","","","","","","","","Geomatics","Synthesis Project 2023",""
"uuid:67115455-a15f-44df-aa7c-96b70c3bfdef","http://resolver.tudelft.nl/uuid:67115455-a15f-44df-aa7c-96b70c3bfdef","A Comprehensive Study of Dynamic SLAM: From Realistic Dynamic Environment Simulation Towards Robust Visual Localization","Xu, Chenghao (TU Delft Mechanical, Maritime and Materials Engineering)","Alonso-Mora, J. (mentor); Bonetto, E. (mentor); Ahmad, A. (mentor); Wisse, M. (graduation committee); Kok, M. (graduation committee); Delft University of Technology (degree granting institution)","2023","In recent years, visual Simultaneous Localization and Mapping (SLAM) have gained significant attention and found wide-ranging applications in diverse scenarios. Recent advances in computer vision and deep learning also enrich visual SLAM capabilities in scene understanding and large-scale operation. However, despite remarkable performance in these fields, most visual SLAM frameworks are designed with the static world assumption. Thus, they often confront challenges in dynamic environments, manifesting reduced localization accuracy, tracking failures, and restricted generalization.
To investigate the impact of moving objects in dynamic indoor environments, we first benchmark representative visual (dynamic) SLAM approaches, complemented by robustness assessments for preliminary insights. During this process, we adopt challenging sequences from GRADE, an ideal platform for simulating dynamic indoor scenes. Notably, the mainstream of dynamic SLAM methods employs detection or segmentation techniques as solutions. To explore the correlation between detector accuracy and overall SLAM performance, we integrate a series of trained YOLOv5 and Mask R-CNN models, each with varying accuracy levels, into dynamic SLAM systems. Subsequently, we evaluate these configurations on the TUM RGB-D sequences. Contrary to common intuition, the experiments indicate that more accurate object detectors do not necessarily lead to improved visual SLAM performance. This benchmarking process also illuminates several inherent limitations of current dynamic SLAM techniques, underscoring the imperative for further advancements.
Building upon these insights, we introduce DynaPix SLAM, an innovative visual SLAM system for dynamic indoor environments, where participation of visual cues (e.g., features) is weighted based on per-pixel motion probability values. Our approach consists of a semantic-free pixel-wise motion estimation module and an improved pose optimization process. In the first stage, our motion probability estimator employs a novel static background differencing method on both images and optical flows to identify moving regions. These probabilities are then incorporated into the map point selection and weighted bundle adjustment for backend optimization. We evaluate our DynaPix SLAM and its variant, DynaPix-D, in comparison with ORB-SLAM2 and DynaSLAM. These assessments are performed on both TUM RGB-D and GRADE sequences, with additional tests on the static versions of the GRADE ones. The results demonstrate that DynaPix SLAM consistently outperforms the other methods, showcasing reduced localization errors and longer tracking durations across various scenarios.
The academic works on malware remediation focus on system replay and recovery-oriented computing, which relies on heavy monitoring and is not suitable for a normal user’s personal computer. The work from Paleari et al. [31] proposed a remediation methodology that can be used entirely after the infection. They run the malware sample in the sandbox to observe the behavior and generate a revert operation for each action that modifies the system state. However, the limitation of such an approach is unable to deal with the potentially different behaviors in the sandbox and on the real hosts.
In this work, we propose a system that can generate user-specific recovery procedures, without the need of any monitoring in advance. We extend the work from Paleari et al. [31] by combining information from the infected machine. We first extract the environment configuration from the infected computer and configure the same context to the sandbox virtual machine, in order to eliminate the environmental influence on the malware’s behavior. After getting the behavior from the sandbox, we combine forensic evidence to understand the exact actions that happened on the system and generate the user-specific recovery procedures.
We implement a prototype based on Windows 10 and CAPE sandbox and perform an evaluation on 894 malware samples. We are able to recover 51.3% of the changes made by malware, which doubles the recovery rate compared to directly matching the sandbox result. Additionally, our experiment result also demonstrates significantly different actual behavior from the user’s machine and sandbox result. Our system design maximizes the use of information displayed in the sandbox, but the unshown behavior still leads to the biggest limitation of behavior-based recovery.","Malware Remediation; Forensic Analysis; Environment-sensitive Malware; Automatic Recovery","en","master thesis","","","","","","","","","","","","Computer Science","",""
"uuid:cadbcbd1-04b3-463c-a96a-98e963a4bb94","http://resolver.tudelft.nl/uuid:cadbcbd1-04b3-463c-a96a-98e963a4bb94","End-to-End Federated Diffusion Generative Models for Tabular Data","Xu, Jiaming (TU Delft Electrical Engineering, Mathematics and Computer Science)","Brower, Hans (mentor); Chen, Lydia Y. (graduation committee); Migut, M.A. (graduation committee); Delft University of Technology (degree granting institution)","2023","Tabular data is widely used in various fields and applications, making the synthesis of such data an active area of research. One important aspect of this research is the development of methods for privacy-preserving data synthesis, which aims to generate synthetic data that retains statistical properties while protecting the privacy of individuals in the dataset. Recently, Diffusion Generative Models, such as Gaussian Diffusion Model, have significantly improved image synthesis, but their effectiveness in synthesizing tables is limited, because of using One-Hot encoding for representing categorical attributes with many categories. Furthermore, it needs the private data to be centrally collected for training, thus violating the privacy-preserving criteria. In this paper, we propose a new decentralized tabular synthesizing framework, which has three key features: (i) a decentralized Autoencoder comprised of an encoder and a decoder to map discrete features into the continuous space and back, (ii) a tabular diffusion model trained in a decentralized manner and (iii) incorporating differential privacy on central stochastic gradient training. We conduct extensive experimental studies that focus on sampling quality and diversity, using 9 tabular datasets and 4 state-of-the-art synthesizers. The results show that our method outperforms existing central methods by 10.7% and 31.4% in data quality and diversity on average, and 6.8% and 21.1% in data quality and diversity in scenarios facing non-IID data.","Tabular Data Synthesizer; Federated Learning; Diffusion Generative Model","en","master thesis","","","","","","","","","","","","Computer Science","",""
"uuid:5c1065b7-9dcd-4079-bd87-30b041266deb","http://resolver.tudelft.nl/uuid:5c1065b7-9dcd-4079-bd87-30b041266deb","Iris - A knowledge Graph-based chatbot for Explaining Robotic Scenario Information to Human Operators in a Retail Setting","Xu, Ke (TU Delft Mechanical, Maritime and Materials Engineering)","Hernández, Carlos (mentor); Mercuriali, P.R. (graduation committee); Eisma, Y.B. (graduation committee); Pezzato, C. (graduation committee); Delft University of Technology (degree granting institution)","2023","The problem of assisting users in comprehending the robotic scenario information in a retail setting has been studied. To design the system, an integrated ontology composed of several IEEE standard ontologies and a labelled property graph (LPG)-based ontology modified from the Web Ontology Language (OWL)-based ontology was proposed to symbolize information in the robotic environment. Then, a knowledge graph (KG)-based chatbot was developed to provide natural language interaction with users. A case study in a retail setting was designed, and the results were analyzed. The effectiveness of our designed system has been experimentally validated in both static and dynamic scenarios, with at least 1.5 times improvements.","Knowledge Representation; Ontology; Knowledg Graph; Chatbot; Human-Robot Interaction","en","master thesis","","","","","","","","2024-08-31","","","","Mechanical Engineering | Vehicle Engineering | Cognitive Robotics","",""
"uuid:f9755750-36b6-451f-a733-7c7ad9448330","http://resolver.tudelft.nl/uuid:f9755750-36b6-451f-a733-7c7ad9448330","Rail Corridor Object Detection and Positioning Improvement from a Railway Mobile Mapping System","Xu, Zelin (TU Delft Civil Engineering & Geosciences)","Lindenbergh, R.C. (mentor); Amoureus, Luc (graduation committee); Amiri Simkooei, A. (graduation committee); Yang, Michael (graduation committee); Delft University of Technology (degree granting institution)","2023","There are multiple types of objects distributed along the rail trackside to support the operation of railroads. Damage to those objects will result in delay and cancellation of trains. Therefore, the maintenance of the objects is important to ensure the safety of railway operations, and the key to maintenance is to know the accurate position of the objects. RILA - a railway mobile mapping system developed by Fugro - provides continuous monitoring of the rail environment without interrupting the daily operation of rail tracks. The RILA dataset contains different types of data including video frames, point clouds, and measurement trajectories from the Global Navigation Satellite System and Inertial Measurement Unit (GNSS-IMU). This enables a remote and automatic object positioning process based on object recognition in video frames and positioning using photogrammetric techniques.
Most of the rail trackside objects are parts of the railway electrification system and the railway signaling system. The available ground truth data contains more information about signaling objects, so this thesis mainly focuses on the positioning of signaling objects. Three typical components: signal lights, railway cabinets, and railway side markers are selected to make case studies and develop the object detection and localization pipeline for them.
There are two main issues that existed in former research: One is object recognition only gives a 2D pixel position for an object, but we want to know its 3D position in the world; the other is the contextual information between frames is ignored in object positioning. Based on that, this thesis developed a new workflow: firstly, this thesis proposes the use of an existing 3D object detection model, Single-Stage Monocular 3D Object Detection via Keypoint Estimation (SMOKE), to recognize objects of interest from the RILA video frames. This model can not only predict an object's 2D pixel position on the image, but also its 3D position with respect to the camera. This enables the localization of an object in each of the frames it is detected in, which provides redundancy to define its final position. Secondly, this thesis developed a pipeline to clean the detection output of SMOKE so that most false detections can be removed. In addition, this thesis developed a method to use the contextual information in image sequences to position objects: first, extract the sequences by classifying all the predictions in the detection output through the Euclidean distances, then for each sequence, analyze the varying trend of predicted positions to select reliable positions. The mean of the selected positions is the final improved position of that object. By making tests on a part of the railway near Ely, UK, with 2983 frames, the workflow detected and positioned all of the 4 signal lights, all of the 10 markers, and 13 of the 14 cabinets in the testing dataset. Most signal lights and cabinets can be positioned within 1 meter to the ground truth, and the mean positioning offset for the railway side markers can be controlled around 2 meters. Complex scenarios could be solved, when up to three cabinets were located close together.","","en","master thesis","","","","","","","","2025-02-28","","","","Geoscience and Remote Sensing","","52.41469393, 0.29598187"
"uuid:073667c0-2b33-403b-9668-e93308136cab","http://resolver.tudelft.nl/uuid:073667c0-2b33-403b-9668-e93308136cab","Fouling control in ceramic nanofiltration membrane by pre-coating with calcium carbonate","Xu, Yidan (TU Delft Civil Engineering & Geosciences)","Heijman, Sebastiaan (mentor); Rietveld, L.C. (graduation committee); Chassagne, C. (graduation committee); Li, L. (graduation committee); Delft University of Technology (degree granting institution)","2022","Water scarcity and uneven distribution of water resources pose a significant challenge globally. Searching for alternative water resources could alleviate this issue. Municipal sewage reclamation with ceramic NF membrane has gained momentum nowadays. However, the inevitable fouling, especially organic fouling during membrane filtration, is the major limitation of the application. To mitigate the fouling issues and protect the membrane from frequent sodium hypochlorite cleaning, a reaction-based CaCO3 pre-coating method, which could prevent the direct contact of foulant and ceramic NF surface was developed. Acid cleaning was applied to initiate the reaction between CaCO3, which was attached with foulants (sodium alginate) and acid. Lastly, forward flush was implemented to remove the loosened CaCO3 and sodium alginate layers.
The effectiveness of hydrochloric acid cleaning, formic acid cleaning and citric acid cleaning was studied in this paper. Citric acid was found to be the most effective way of cleaning because of the highest permeability recovery rate obtained and the lowest consumption rate of the pre-coating layer. This could be ascribed to the carboxyl groups chelation with calcium ions and the ‘peeled’ chelates adsorbed with more foulants were flushed away. Formic acid was less efficient showing moderate efficiency. Besides, HCl cleaning restored the lowest extent of membrane permeability. Additionally, experiments of increasing the pre-coated CaCO3 amount (7655 mg/m2) to apply for more filtration/acid cleaning cycles were executed. The effectiveness increases in the order of HCl, formic acid and citric acid. The pre-coated membrane cleaned with citric acid could last for the whole six cycles, while the membrane cleaned with HCl only worked in the first three cycles. Lastly, the effect of bubbles generated during the reaction was explored using CaHPO4 as a pre-coating layer. However, the hypothesized positive impact of bubbles was not verified.
However, there are barriers impeding distributed energy development regarding financial, technological, regulatory, resources and awareness aspects. To overcome obstacles to DSPV development, several scholars emphasized the importance of promoting business model innovation (BMI) in DSPV projects. Before any further design and implementation, a comprehensive understanding of BMI is essential. The fundamental step is to identify the origins of BMI and investigate how DSPV projects enterprises can capture and subsequently respond to changes within and external to their businesses.
This work aims to investigate business model innovation for distributed solar photovoltaic project companies through dynamic sustainable business model frameworks. The main research question is “How can we develop a dynamic sustainable business model framework to understand business model innovation in distributed solar PV (DSPV) projects in China?” The objective is to develop dynamic sustainable business model framework and then apply it to DSPV project companies in China in order to understand business model innovation.
Through the study, business model innovation at the firm level (DSPV project enterprise) is a dynamic process. Due to environmental and business variables, a company’s business model constantly changes in response to external and internal opportunities and threats. These variables are essential for understanding business model innovation. Changes in external factors (e.g., policy and regulation, industrial technology innovation, customer demand, market competition, etc.) and internal factors (e.g., company technology improvement, project O&M management, personnel capability, etc.) could trigger business model innovation. Starting with recognizing opportunities or threats, DSPV enterprises respond to these variables differently depending on company capability and external business environment. Meanwhile, changes within business model elements tend to be coherent and interlinked over time. For an efficient business model innovation, associated business model elements are supposed to be in line with a changed business model element. On the way, these changes can either create or capture value for stakeholders, including customers, society and the environment. The constantly changing process as to BMI is based on a company’s flexible operation and management for adapting to the complex and varying environment.","Dynamic Sustainable Business Model Framework; Business Model Innovation; Distributed Solar Photovoltaics; Business Model Dynamics","en","master thesis","","","","","","","","","","","","Electrical Engineering | Sustainable Energy Technology","",""
"uuid:79f0de7f-ea94-4c53-bbe7-f38d2bae3f71","http://resolver.tudelft.nl/uuid:79f0de7f-ea94-4c53-bbe7-f38d2bae3f71","Study of the transport properties of hydrogen in aqueous solutions at conditions relevant to underground hydrogen storage","Xu, Ke (TU Delft Mechanical, Maritime and Materials Engineering)","Dey, P. (mentor); Moultos, O. (mentor); Habibi, P. (graduation committee); Ramdin, M. (graduation committee); Delft University of Technology (degree granting institution)","2022","","","en","master thesis","","","","","","","","2024-07-19","","","","","",""
"uuid:46e9c11e-03e9-4c7b-8d10-0040847d6d3e","http://resolver.tudelft.nl/uuid:46e9c11e-03e9-4c7b-8d10-0040847d6d3e","A privacy-preserving tamper-evident revocation mechanism for verifiable credentials","Xu, Li (TU Delft Electrical Engineering, Mathematics and Computer Science)","Erkin, Z. (mentor); Li, T. (graduation committee); Pouwelse, J.A. (graduation committee); Al-Ars, Z. (graduation committee); van Deventer, Oskar (graduation committee); Delft University of Technology (degree granting institution)","2022","Third-party verified credentials (e.g. passports, diplomas) are essential in our daily life. The usage of third-party verified credentials bring us convenience in authentication. The Verifiable Credential (VC) data model is a new standard proposed by the W3C association to ease the expression and verification of third-party verified credentials on the Internet. The issuance and presentation of verifiable credentials are tamper-evident and privacy-preserving by design. However, the current verifiable credential data model lacks an explicit revocation design that guarantees the secure operations of the system. The lack of a revocation mechanism significantly limits the application of verifiable credentials. This thesis studies the revocation mechanisms of existing verifiable credential implementations. The existing revocation mechanisms are either tamper-evident or privacy-preserving. None of them can achieve the two properties together. To evolve the revocation mechanism to be both tamper-evident and privacy-preserving by design, we propose a new method which combines the BBS+ signature, a cryptographic accumulator and the blockchain. Our design enables the verifier to verify the presented credential’s revocation status without compromising the credentials holders’ privacy. We implement a proof-of-concept of our revocation mechanism to show it is practical in the real world. The experimental results show that after adding our revocation mechanism, the presentation time of a five-attribute credential changes from 22.22ms to 62.11ms (+39.89ms), and the verification time changes from 13.36ms to 44.56ms (+31.86ms). Moreover, the scalability analysis shows that our revocation mechanism can satisfy the need for revocation in the real world.","Revocation; Verifiable Credential; Zero-knowledge Proof","en","master thesis","","","","","","","","","","","","Computer Science | Cyber Security","",""
"uuid:cb6408f5-22b6-46c9-b191-bcc6c5b1de4b","http://resolver.tudelft.nl/uuid:cb6408f5-22b6-46c9-b191-bcc6c5b1de4b","Approximate Gradient Inversion Attack on Federated Learning","Xu, Jin (TU Delft Electrical Engineering, Mathematics and Computer Science)","Chen, Lydia Y. (mentor); Decouchant, Jérémie (mentor); Liang, K. (graduation committee); Delft University of Technology (degree granting institution)","2022","Federated learning is a private-by-design distributed learning paradigm where clients train local models on their own data before a central server aggregates their local updates to compute a global model. Depending on the aggregation method used, the local updates are either the gradients or the weights of local learning models. Unfortunately, recent reconstruction attacks apply a gradient inversion optimization on the gradient update of a single mini-batch to reconstruct the private data used by clients during training. As the state-of-the-art reconstruction attacks solely focus on single update, realistic adversarial scenarios are overlooked, such as observation across multiple updates and updates trained from multiple mini-batches. A few studies consider a more challenging adversarial scenario where only model updates are observable, and resort to computationally expensive simulation to untangle the underlying samples for each local step. In this paper, we propose AGIC, Approximate Gradient Inversion Attack, that efficiently and effectively reconstructs images from both model or gradient updates, and across multiple epochs. In a nutshell, AGIC (i) approximates gradient updates of used training samples from model updates, (ii) leverages gradient/model updates collected from multiple epochs, and (iii) assigns increasing weights to layers with respect to the neural network structure for reconstruction quality. Our experiment results show that AGIC increases the peak signal-to-noise ratio (PSNR) by up to 50% compared to two representative state-of-the-art gradient inversion attacks. Furthermore, AGIC is faster than the simulation-based attack, e.g., it is 5x faster when attacking FedAvg with 8 local steps in between model updates.","Reconstruction Attack; Federated Learning; Federated Averaging","en","master thesis","","","","","","","","","","","","Computer Science","",""
"uuid:3f7699a6-82cd-48cd-87c7-cf9f1d56f872","http://resolver.tudelft.nl/uuid:3f7699a6-82cd-48cd-87c7-cf9f1d56f872","Error model for beam-forming system: Antenna Dome 2.0","Xu, Bo Wen (TU Delft Electrical Engineering, Mathematics and Computer Science); Kamminga, Arjan (TU Delft Electrical Engineering, Mathematics and Computer Science)","Spirito, M. (mentor); Coesoij, R.A. (mentor); Ishihara, R. (graduation committee); Delft University of Technology (degree granting institution)","2022","A new antenna measurement setup, the Antenna Dome, is being developed, which can provide real time antenna and beamformer measurements. In order to be able to validate this setup, an existing beamforming system will be will be extensively studied and characterized. Multiple measurement setups will be used, providing multiple measured characteristics. The result is an accurate statistical model for the steering system, and a comprehensive error model for the complete beamforming system, including the provided antenna array. This model will help in validating the functionality of the Antenna Dome, and ultimately will help in its further development.","Dome; Antenna dome; Error model; calibration","en","bachelor thesis","","","","","","","","","","","","Electrical Engineering","",""
"uuid:6da7a26e-9e91-4a05-9382-d24da6912f7e","http://resolver.tudelft.nl/uuid:6da7a26e-9e91-4a05-9382-d24da6912f7e","The Protein Factory: An inclusive spatial strategy for the transition towards a sustain- able system of protein-based food within the province of South Holland","Kalentzi, Arda (TU Delft Architecture and the Built Environment); Schoemakers, Miriam (TU Delft Architecture and the Built Environment); Vitkutė, Ruta (TU Delft Architecture and the Built Environment); Xu, Shiming (TU Delft Architecture and the Built Environment)","Qu, L. (mentor); Calabrese, L.M. (mentor); Van den Berghe, K.B.J. (mentor); Delft University of Technology (degree granting institution)","2022","","","en","student report","","","","","","","","","","","","Architecture, Urbanism and Building Sciences | Urbanism","AR2U086 R&D Studio – Spatial Strategies for the Global Metropolis",""
"uuid:0345dc7a-fc90-4c25-a393-d5b4285bd16d","http://resolver.tudelft.nl/uuid:0345dc7a-fc90-4c25-a393-d5b4285bd16d","Multifunctional UV-C LED Virus Inactivation Experimental Platform","Xu, Xinyun (TU Delft Electrical Engineering, Mathematics and Computer Science; TU Delft Microelectronics)","Zhang, Kouchi (mentor); van Driel, W.D. (graduation committee); Jin, T. (graduation committee); Bossche, A. (graduation committee); Delft University of Technology (degree granting institution)","2021","Since the outbreak of SARS-COV-2, various virus inactivation techniques have been applied to suppress the spread of virus. Ultraviolet exposure inactivation is an efficient approach to inactivate virus, within UV band, UV-C with comparatively higher energy. UV-C has been proved to inactivate viruses efficiently, while to figure out efficient inactivation approach, virus reduction rate as a function of UV-C wavelength with different viral sensitivity and quantitative exposure dose should be measured through experiments.
On the one hand, miniatured, energy-efficient and fully-customized UV-C light-emitting diodes (LED) offer possibility of switching wavelengths and adjusting quantitative optical properties, on the other hand, UV-C LEDs have been produced with the latest technology based on Aluminium gallium nitride (AlGaN).
~\\Multifunctional UV-C LED Virus Inactivation Experimental Platform is a system designed with replaceable UV-C wavelengths, controllable light intensity and exposure time for quantitative virology experiments. The system has an initial design for standard virology experimental equipment which offers a new and consistent tool for virus researchers. The Inactivation Platform has been assembled and utilized to perform several Influenza A (ssRNA virus) inactivation experiments in order to obtain reduction rate as a function of UV-C wavelength and exposure dose with Germicidal Curve and Inactivation Curve respectively.
~\\After inactivation experiments implementation and result analysis, the inactivation mechanism on the basis of molecular dynamic research theory and simulation is supposed to be figured out. Due to the complexity of proteins in virus, the research focuses on Nucleic Acid Bases (NABs) as target genetic viral material. The absorbed ultraviolet energy results in ultrafast decay, including molecular electronic transition, virus structure variation (Dimerization) theoretically. The absorbed energy along the band is revealed with Absorption Spectrum, and the potential electronic transition depends on the initial structure NABs, together with inside chemical bonds. When absorbed energy populates the molecules to transition state, ultrafast decay takes place because of the existence of Gibbs energy of activation. In the light of molecular dynamic simulation, it proves that compared to ground state, excited state leads to lower standard Gibbs energy of activation, causing higher reaction rate (faster inactivation speed).","virus inactivation; UV-C LED; wavelength; light intensity; inactivation mechanism","en","master thesis","","","","","","","","2023-09-30","","","","Electrical Engineering | Embedded Systems","",""
"uuid:db96d13d-50be-41c8-80b8-555f36870ba6","http://resolver.tudelft.nl/uuid:db96d13d-50be-41c8-80b8-555f36870ba6","Play-cycle: The migration of play and play spaces","Xu, Yi (TU Delft Architecture and the Built Environment)","van Bennekom, H.A. (mentor); van der Meel, H.L. (mentor); Mateljan, M. (mentor); Delft University of Technology (degree granting institution)","2021","Play, as a practise which has a huge impact on individual human growth and social relationships, has been researched in contexts of multiple disciplinary fields. Theories of play have been developed in different realms and instructed the design of diverse play spaces. Specific architectural typologies as well as general principles of urban planning have been taking inspirations from the migrated idea of ‘play’. However, few studies or practices have explored how ‘play’ can be applied on a neighbourhood level as a solution to the poor development of both its residents and the community itself. This paper takes Feijenpoort area as a research subject to address the missing intermediate dimensions in the migration of ‘play’. Through historical research this paper argues a correlation of the emergence of new behavioural and spatial play to the social condition. A new design program of ‘play-cycle’ is proposed after comparative studies of existing play space typologies to revitalise the neighbourhoods through positive participation of its young population.","Play; Playscape; Playfulness; Rotterdam Zuid; Community education","en","master thesis","","","","","","","","","","","","Architecture, Urbanism and Building Sciences","","51.893370943990185, 4.501338619137428"
"uuid:7ad9cd56-ad79-4053-a94a-521132d24cd5","http://resolver.tudelft.nl/uuid:7ad9cd56-ad79-4053-a94a-521132d24cd5","Bricolage in city renovation: Student apartment design in Nijmegen","Xu, Jingyu (TU Delft Architecture and the Built Environment)","Vermeulen, P.E.L.J.C. (mentor); Fokkinga, J.D. (mentor); Reinders, L.G.A.J. (mentor); Delft University of Technology (degree granting institution)","2021","Bricolage is a interesting word.It was used with reference to some extraneous movement and means an unexpected result,It was later derived as a
means of solving problems only using the tools at hand. And this essay is a journey to compare bricolage in daily life and bricolage in architecture field to discover what bricolage means in city renovation in both urban and architecture scale.","bricolage; reuse; Renovation","en","master thesis","","","","","","Rossi, Aldo, and Peter Eisenman. The architecture of the city. MIT Press. 1982. Kevin Lynch. The image of the city. MIT Press.1960 Claude Lévi-Strauss. the savage mind. MIT Press. 1962. Colin Rowe. Collage City.MIT Press.1978 Robert Venturi. Complexity and Contradiction in Architecture.1966 Roger Trancik. Finding Lost Space: Theories of Urban Design. 1986 Charles Jenks. Adhocism: The Case for Improvisation.1972 Heidegger, Martin. ""The Thing"". 1971 Brown, B. A Sense of Things. University of Chicago Press. 2004.","","","","","","Architecture, Urbanism and Building Sciences | Building Technology","",""
"uuid:7bfcf41b-68fe-4aa8-90f2-7894b3fcaf82","http://resolver.tudelft.nl/uuid:7bfcf41b-68fe-4aa8-90f2-7894b3fcaf82","Let's walk! Design the gait test station for children","Xu, Chenye (TU Delft Industrial Design Engineering)","Gielen, M.A. (mentor); Weerdesteijn, J.M.W. (mentor); Roebroeck, M.E. (mentor); Delft University of Technology (degree granting institution)","2020","This project aims at designing a gait test station for children. The gait test station tests children’s walking in Child Brain Lab at Sophia Children’s hospital. The children in this project are at the age of 4-10 with different capacities.
There are two scopes in this project, the service scope of the gait test and the experience scope of children. The service scope is to define the current procedure of the gait test. The procedure includes the gait test device, the gait test process, and the test conductor’s working experience. A service blueprint specifies the entire procedure. Another research with physical therapists, child experts, and parents by questionnaire is conducted in the service scope. With those experts’ experiences, I understand children’s related capacities to follow and finish a gait test; some design opportunities also are found. Regarding the scope of children’s experience, as the gait test station has not been set up at the hospital, the research with children is conducted at home, based on the defined service blueprint. In the Covid-19 situation, the children are researched remotely or at the family home with permission. With the research results, children’s current situations are defined and depicted in the experience maps. The current situations are four different typical situations at the gait test station. After the series of research activities, children’s current problems at the gait test station are defined. I formulate my design goal as Design an experience journey for children’s (aged 4-10) gait test to induce their natural walking, make them motivated and fun, or learn about the walking. A shortlist of design requirements is also concluded in the service scope. Before the design phase, there is a project phase of design sprints. I test and iterate different interventions in this phase for several rounds. With the intervention iterations, I can emphasize more on children to better design for them. With the iteration results, the design patterns are concluded on children’s experience maps. A list of design elements is also concluded from the iteration interventions. In the design phase, concepts have been generated with the combination of all the design patterns. As these are the combined concepts, I first evaluate if the concept includes all the design elements in different design patterns. The concepts are also evaluated with the hospital in the service scope. With these two evaluations, one concept has been selected. This concept contains three different tasks for different types of children. The three tasks are exploring walking knowledge, imitating animal walking, and sending animals to the jungle. Children can have one task during the gait test to achieve the envisioned experience. In the final concept, the technology tool is changed from the previous concept to enhance the walking experience. With the final concept, a new service blueprint and a technology roadmap are made as final deliverables. Considering a long-term implementation, I also implemented the concept into the interactive videos for short term use. The interactive videos can directly work at the gait test station, also as a final deliverable.","Value-based healthcare; Experience design; Design for children","en","master thesis","","","","","","","","","","","","","",""
"uuid:74aabb03-145f-4edf-817c-1731bab086d2","http://resolver.tudelft.nl/uuid:74aabb03-145f-4edf-817c-1731bab086d2","Procedural Content Generation for Math Education","Xu, Y. (TU Delft Electrical Engineering, Mathematics and Computer Science)","Bidarra, Rafael (mentor); Eisemann, Elmar (graduation committee); Lofi, C. (graduation committee); Delft University of Technology (degree granting institution)","2020","Mathematics education plays an essential role in children’s development. In the past few years, online mathematics learning has gained increasing popularity. The online learning platform needs a large variety of textual and visual content to offer children a convenient learning experience and help them practice various mathematical skills. However, manually creating content is hugely time-consuming, expensive, and tedious for the content editors.
This project proposes a generic approach for procedural generation of mathematical problems and corresponding textual and visual content. We analyzed and clustered hundreds of primary school curriculum-based math knowledge components, and built flexible templates for generating abstract math problems, including arithmetic, comparison, ordering, mathematical relationships, measurements, and geometry. Then our system realizes the abstract math problems in natural language through the lexicalization of language-independent semantic configurations and syntactically structured templates. Our system generates visual content through text-based image retrieval and visualization of abstract math content, varying in the forms of table, chart, geometry, or picture for counting objects. Human expert evaluations found that our generated contents are understandable, sensible, and achieve well usefulness for primary school students.","Procedural Content Generation; Math Education; Online learning","en","master thesis","","","","","","","","","","","","Computer Science","",""
"uuid:bb66d107-f6eb-4aef-9f34-ad365bad0667","http://resolver.tudelft.nl/uuid:bb66d107-f6eb-4aef-9f34-ad365bad0667","A Surface EMG System: Local Muscle Fatigue Detection","Xu, Wencong (TU Delft Electrical Engineering, Mathematics and Computer Science)","Bossche, Andre (mentor); French, Paddy (graduation committee); Steijlen, Annemarijn (graduation committee); Bastemeijer, Jeroen (graduation committee); Delft University of Technology (degree granting institution)","2020","In the last 4 decades, surface electromyography (sEMG) signal processing has been applied to detect local muscle fatigue, this non-invasive approach is suitable for detecting EMG signals generated by athletes in motion. Also, EMG could directly reveal the muscle’s performance like endurance and recruitment of motor units, which is hard to be obtained by other methods. With the sEMG system, we can research whether EMG signals can be used to measure muscle fatigue and how this relates to injury risk. This thesis aims to build a sensor node for sEMG to detect local muscle fatigue. An sEMG system is built for this purpose, and a physiological experiment is designed to collect sEMG signals from human muscle (Vastus Medialis) using the sEMG system. Both isometric and isotonic exercises are studied. The data analyzing method is calculating mean power spectrum frequency (MNF), median power spectrum frequency (MDF), and muscle fiber propagation velocity (MFPV) of the collected sEMG signals, because local muscle fatigue is related to MNF/MDF decrease and MFPV decrease. 5 groups of isometric exercise, wall-sit and 2 groups of isotonic exercise, cycling, are recorded. All the athletes are healthy males, around 25. The data analyzing result shows that MNF/MDF decrease is related to muscle fatigue, and MFPV changes similarly with MNF/MDF.","surface EMG; muscle fatigue; mean power spectrum frequency; median power spectrum frequency; muscle fiber propagation velocity","en","master thesis","","","","","","","","","","","","","",""
"uuid:abe18eff-03a2-4837-a73a-a366735102db","http://resolver.tudelft.nl/uuid:abe18eff-03a2-4837-a73a-a366735102db","An Investigation into Solution Strategies for Nonlinear Finite Element Analysis of a Concrete Column under Blast Loading","Xu, Jie (TU Delft Civil Engineering and Geosciences)","Hendriks, Max (mentor); Rots, Jan (graduation committee); Tsouvalas, Apostolos (graduation committee); Delft University of Technology (degree granting institution)","2019","An explosion event, having a low probability of occurrence but severe consequences, due to a possible structural collapse, is a so-called ""Low Probability and High Consequences (LP-HC)"" event[13]. Due to the severe consequences, blast puts a great threat to public security. Thus, civil engineers should take these extreme cases into consideration during the design process to ensure the integrity of the basic frameworks of the structures to provide the possibility to the following rescue works. Nonlinear finite element analysis is a useful method for civil engineers to check the integrity of the structures under blast loading. However, there could be lots of different solution strategies for the same physical situation that may lead to differences in the corresponding numerical results. A solution strategy is a certain combination of different options in all the steps during the setting-up of the finite element model, including the definition of loads, boundary conditions, material models, element types and element sizes. Therefore, to which extent can civil engineers simulate the dynamic behavior of experiments of concrete columns with blast loading by nonlinear finite element analysis is of great interest. In this thesis, 36 different solution strategies for the same physical situation are discussed. DIANA 10.2 Educational Version is applied to generate numerical results of finite element models with different solution strategies. The modelling of boundary conditions, bond effect between steel reinforcements and concrete, blast pressure profiles and the choice of element types and the order of element on the numerical results are investigated and discussed in this thesis by dividing the 36 models into 51 groups. And the question about to which extent can we reduce the computation time while the accuracy is still satisfying is addressed.
Firstly, an investigation of literature is performed. Column CONV-7 from Test 1 of Siba’s report is selected. The blast pressure profiles at the bottom, and top of the front face of the column, and the bottom, the mid-height, and the top of the rear face of the column were recorded with pressure gauges. The displacement-time diagrams of the 1.0 m, 1.5 m and 2.0 m from the column footing of the rear face of the column were recorded while only the diagram at 1.0 m from the column footing was reliable. Then the finite element analyses with different solution strategies are performed and compared in groups. In this treatise, 36 finite element analyses with different solution strategies are performed. The numerical displacement results at 1.0 m from the column footing of the rear face of the column are compared to the experimental results.The errors of these finite element analyses with different solution strategies vary from 3.476% to 50.116%. Thus, the choice of solution strategies has a significant influence on the accuracy of the numerical results for nonlinear finite element analyses for this situation. However, there is only a limited number of solution strategies are discussed and only the displacement results at 1.0 m from the column footing are compared, therefore, the solution strategy with the lowest error may not be the most recommended one. The inclusion of the negative phases of the blast pressure profiles has an increasingly significant influence on the evaluation of the safety of those structures and structural components that are not destroyed before reaching the largest deformation in the direction of wave propagation, which differs from Karlos’ statement[17]. The modelling of damping effect with Rayleigh damping coefficients for the structures may not be very suitable, which disagrees with the example listed in the manuals of DIANA 10.2[1]. interpretation and modelling of the boundary conditions have an important influence on the numerical results, for the models with simplified geometries, modification of boundary conditions is required. The first-order elements, due to the uniform mass distributions and fewer degrees of freedom, are more recommended for both accuracy and efficiency reasons. The choice of mesh sizes in the support structure has a limited influence on the numerical results
as the support structure is less sensitive to the blast loading. The modelling of bond-slip effect between the rebars and concrete would lead to limited differences in the numerical results, this may due to the overestimation of the shear stiffness of the interface elements between the reinforcements and concrete. The finite element models with plane stress elements generally yield to a conservative result in the displacement due to the neglect of the out-of-plane deformation and the confinement of the ties is not included due to the neglect of the transverse rebars in the direction that perpendicular to the wave propagation.","Explosions; Nonlinear Analyses; NLFEM; Transient Analyses; Solution Strategies","en","master thesis","","","","","","","","2019-12-31","","","","Civil Engineering","",""
"uuid:b9cd47d6-c54f-40f4-95f9-4e9624f1c859","http://resolver.tudelft.nl/uuid:b9cd47d6-c54f-40f4-95f9-4e9624f1c859","Improving location accuracy of a crowdsourced weather station by using a point cloud: Use case based Netatmo on the Hague","Xu, Yixin (TU Delft Architecture and the Built Environment)","Ohori, Ken Arroyo (mentor); Wandl, A. (mentor); Delft University of Technology (degree granting institution)","2019","The world’s continuously increasing population leads to environmental challenges, among which, the urban heat island effect has been recognized as one of the leading environmental issues recently. Using traditional weather station (usually one or two within one city and placed in rural area) to monitor and model the canopy layer urban heat phenomenon does not provide enough spatial resolution. Alternatively, the Netatmo weather station, a low cost and citizen science weather sensor, is able to collect crowdsourced temperature records and has significant strength in spatial and temporal resolution in temperature measurement. Thanks to the variety of uses of the Netatmo weather station and its open API, more temperature data could be used for UHI research. However, for scientific use, the main challenge is the data quality. For one thing, the stations’ locations are set by users and are thus not accurate enough for temperature modeling in a complex city environment. For another, sensors some time generate unreliable records when exposed to solar radiance directly. These two things are actually highly interactional. Knowing the accurate location of stations could be helpful to calculate when the stations are exposed sun then filter outliers, and vice versa. However, the location information could be used to improve its accuracy is quite limited. Thus, the current work is focusing on develop an approach to determine the likely correct location of the stations. For the development of the relocation method, different spatial and sensor datasets have been used. The temperature data in the Hague in May, 2018 have been collected from Netatmo weather stations. Additionally, the AHN3 points cloud for solar simulation and BGT shapefile for creating new location have been investigated. The methodology of relocation process is divided into 6 steps: Sensor data pre-processing, Detecting higher temperature time, Generating potential location of stations, Computing sky view (dome) and solar parameter, Finding the most likely horizontal location of the station, and Assigning height value to points. These steps also have been used with another period time in the Hague for validation and one sample Netatmo sensor experiment in Delft will be conducted. The results proved the feasibility and rationality of the adopted methodology. Around 67% stations (new location) is shown more than 0.5 similarity when comparing with their solar simulation. Validation result detained by two period comparison indicates that over 70% Netatmo stations’ new location show high quality on both the horizontal and vertical dimensions after applying the process. Validation experiment is shown a real example of fluctuated air temperature and how it will be influenced by solar radiance. In the experiment, the location error is reduced from 16 meters to 4 meters, which proves that the methodology adopted by the project is helpful to improve the station’s location accuracy.","Crowdsourced data; Netatmo weather station; Location accuracy","en","master thesis","","","","","","","","","","","","Geomatics","",""
"uuid:a1070a5f-7dd4-4be2-b12a-78fd034346ac","http://resolver.tudelft.nl/uuid:a1070a5f-7dd4-4be2-b12a-78fd034346ac","The Space of Dynamic Informality","Xu, Jiayun (TU Delft Architecture and the Built Environment)","Schoonderbeek, Marc (mentor); Rommens, Oscar (graduation committee); Jennen, Pierre (graduation committee); Delft University of Technology (degree granting institution)","2019","Today's standard spatial experience of the contemporary city is like one of a continuous sequence of small homogeneous functional enclaves via thresholds and leftover spaces, which can be summarized as the 'margins', where plenty of temporary or long-lasting informal practices take place. Those marginal spaces, as well as informal practices they host, are being mostly ignored, but still, have great potentials. They are under constant change, always reflecting the needs of their occupants and inhabitants. Interested in this hidden layer of urban ecology, my concern is how can we as an architect react to the existing informal practices, not in way of negation and demolishment, but respect and continuation. My proposal does not pretend to be able to govern the current processes within the site I studied, nor does it pretend to offer solutions to straightforward problems, for example, ‘problems’ within those informal communities along Baku's railway I investigated - actually it is controversial to decide if the ‘problems’ need to be solved or if there are really 'problems' exist. Instead, I applied the theories and image study methods from my research to the new practice. In a complex block with potential in Tbilisi, I introduce a set of infrastructure, which offers marginal spaces available for occupation and use. The characteristics I've concluded in research should also reflect in the materialization.","informal architecture; market; public building","en","master thesis","","","","","","","","","","","","Architecture, Urbanism and Building Sciences","",""
"uuid:224123e8-7101-4e51-b6db-fb712089341a","http://resolver.tudelft.nl/uuid:224123e8-7101-4e51-b6db-fb712089341a","Verification and optimization of nonlinear shell buckling formula of thin-shell structures","Xu, Jie (TU Delft Civil Engineering and Geosciences)","Hoogenboom, Pierre (mentor); van der Veen, Cor (graduation committee); Delft University of Technology (degree granting institution)","2018","Shell is a popular form of structures as it can withstand relative large load with small thickness, which satisfies the aesthetic preference. Due to the curvatures of shell structures, shell can carry the distributed load as membrane forces instead of bending moments. Due to the small thickness, shell structures are highly sensitive to imperfections. As the loads are carried by membrane forces, buckling failure often govern the design of shell structures. The buckling load could be predicted accurately by performing a nonlinear finite element analysis. However, performing a nonlinear finite element analysis is very time-consuming and expensive as a lot of computational efforts required. The currently used design formula of shell structures can lower down the requirement of computation in a great degree while the accuracy is not very satisfying. Different from other types of structures, shell buckling often starts locally, therefore, an assumption is made that shell buckling is a combination of membrane forces and curvatures. Thus, an improved buckling formula is proposed. In this report, the proposed formula is verified and optimized. In addition, the shell behaviour before buckling has been illustrated by a series of figures that show the deformation and stresses at several load steps.","","en","student report","","","","","","","","","","","","Civil Engineering","",""
"uuid:dcc97b15-0b76-4b90-8a22-a86f23cffe3c","http://resolver.tudelft.nl/uuid:dcc97b15-0b76-4b90-8a22-a86f23cffe3c","Modeling the seismic response of a two-storey calcium silicate brick masonry structure with nonlinear pushover and time-history analyses","Xu, Tianqi (TU Delft Civil Engineering and Geosciences)","Rots, Jan (mentor); Messali, Francesco (mentor); Ravenshorst, Geert (graduation committee); Delft University of Technology (degree granting institution)","2018","In the recent years, increasing induced seismic activities have been observed in the northern part of the Netherlands due to gas extraction. These seismic events may cause severe damages to the building stock in this area, which is mainly composed of unreinforced masonry (URM) buildings not designed to withstand seismic loads. An extensive experimental campaign has been carried out at the Stevin II laboratory of Delft University of Technology to characterize the seismic responses of these URM structures. In this framework, a quasi-static cyclic pushover test on a full-scale masonry assemblage has been performed. In this treatise, the seismic behavior of the tested masonry assemblage is modeled and analyzed via finite element analyses. The validation against the experimental results is achieved through nonlinear pushover analyses on a well-built model of the assemblage. Moreover, as the pushover method used in the aforementioned studies is based on static loading, its accuracy and applicability on studying the seismic behavior for this type of masonry structure need to be evaluated. The evaluation is achieved by performing a series of nonlinear time-history analyses on the model to obtain accurate seismic response of the structure. The applied horizontal ground motion is representative of the earthquakes in the Groningen province and the incremental dynamic analysis method (IDA) is employed.
The nonlinear pushover analyses reproduce the test results properly, showing similar maximum base shear forces and asymmetric capacity curves. In both experimental and numerical analyses, cracks start to form at the top and bottom of the masonry piers due to rocking mechanism and the failure of the structure is governed by damages of the wide piers. Moreover, a sensitivity study based on the monotonic pushover analysis shows that the post-peak behavior of the model is directly related to the masonry compressive strength. The incremental dynamic analysis provides similar base shear capacity and failure mechanisms as the nonlinear pushover analysis. However, the maximum displacement is smaller in both loading directions and a more distributed crack pattern is observed. Overall, for the studied masonry house, the pushover method is capable of properly estimating the base shear capacity but the deformation capacity might be overestimated.","unreinforced masonry; seismic response; nonlinear pushover analysis; nonlinear time-history analysis","en","master thesis","","","","","","","","","","","","","",""
"uuid:a7012221-c21a-4462-b4fc-44f6099bcfeb","http://resolver.tudelft.nl/uuid:a7012221-c21a-4462-b4fc-44f6099bcfeb","Modelling and Evaluation of Contact Resistance in High-Efficiency c-Si Solar Cells Featuring Carrier-Selective Passivating Contacts","Xu, Haiyuan (TU Delft Applied Sciences)","Isabella, O. (mentor); Procel Moya, P.A. (graduation committee); Delft University of Technology (degree granting institution)","2018","In this thesis, contact resistivity for carrier-selective contacts (CSCs) is evaluated by using finite element simulations TCAD Sentaurus. First, the process of transmission line measurement (TLM) is modelled and validated based on current-voltage (I-V) data comparison between reference experiment and simulation results on polycrystalline silicon (poly-Si) based CSCs. Simulation and experimental data are in a good agreement, thus confirming that the modeling method accurately describes the main physical mechanism. Therefore, the simulation approach is used to evaluate the resistivity of complete contact stack for poly-Si and silicon heterojunction (SHJ) based CSCs. Simulation results reveals that the contact resistivity exhibits a clear dependence on tunneling mechanisms in terms of potential barrier size and band alignment. For poly-Si based CSCs, SiO2 thickness (potential barrier size) is the prevalent parameter impacting on the contact resistivity. Additionally, proper doping in poly-Si and buried region in c-Si can improve the band alignment, thus the contact resistivity becomes more resilient to the effect of the tunneling barrier. For SHJ based CSCs, low contact resistivity values are achieved with high carrier concentration in TCO and low activation energy in doped thin film silicon layer. In general, low activation energy reduces the potential barrier for carrier transport while high TCO carrier concentration allows a better band alignment. In particular, for p-type contact, high carrier concentration in TCO is crucial to ensure an efficient band alignment for band-to-band tunneling at TCO/doped-layer interface. Additionally, the contact resistance depends also on the bandgap and the thickness of the passivating intrinsic amorphous silicon (i-a-Si:H) as they impact on band alignment and also energy barrier size. Indeed, lower values of contact resistance are calculated for thinner i-a-Si:H and narrow bandgap because the reduction of the potential barrier opposing to hole collection. Finally, the presented simulation platform has the potential and flexibility of predicting the contact resistance for any type of CSC stack in terms of materials and number of layers.","Simulation; TLM; Carrier selective passivating contacts; poly-Si carrier selective contacts; Silicon Herero-junction","en","master thesis","","","","","","","","2021-11-22","","","","Electrical Engineering | Sustainable Energy Technology","NextBase European project",""
"uuid:a6903b37-68c0-4bc9-a8f4-26e2ec7142a1","http://resolver.tudelft.nl/uuid:a6903b37-68c0-4bc9-a8f4-26e2ec7142a1","Analysis of Contrail Formation Regions and Changes due to Climate Impact","Xu, Jinghua (TU Delft Aerospace Engineering; TU Delft Control & Operations; TU Delft Aircraft Noise and Climate Effects)","Grewe, V. (mentor); Snellen, M. (graduation committee); Roling, P.C. (graduation committee); Delft University of Technology (degree granting institution)","2018","As global warming has become a prominent issue for mankind, scientists are working on every possible aspects to slow down its pace. Aviation emission contributes more and more to the anthropogenic climate impact. Contrails contribute to about 30% of the aviation induced RF. Among the options that are proposed to mitigate the formation of contrails, one of it is to reroute the aircraft in a way to avoid flying through the contrail formation regions (CFRs). To carry out this option, it is necessary to have a better understanding of the distribution of the CFRs as well as their seasonal variation and future trend. The CFRs analyzed in this thesis are simulated by EMAC model, the CFRs' characterisations studied include their zonal and meridional coverage length, stretch factor, direction in the vertical and horizontal planes as well as their seasonal variations and future trend.","contrail formation regions; EMAC; seasonal variation","en","master thesis","","","","","","","","","","","","Aerospace Engineering","",""
"uuid:8329ec9e-6f7c-4be4-aef9-e3069da5281a","http://resolver.tudelft.nl/uuid:8329ec9e-6f7c-4be4-aef9-e3069da5281a","Economic revitalization and city branding practices in the old industrial base in northeast China","Xu, Limin (TU Delft Technology, Policy and Management)","de Bruijne, Mark (mentor); Sun, Baiqing (mentor); Delft University of Technology (degree granting institution)","2018","The old northeastern industrial base, including Liaoning province, Jilin province and Heilongjiang province, used to be the most developed areas in China back in 1980s. Now they are going through a tough time in recent years. GDP growth rate of the northeast kept declining and below national average in the past ten years. Liaoning, the biggest economy entity in the northeast, even negative growth in 2015. Two facts should be blamed for, including single industrial structure and rigid governmental and economic system. Main industries in the northeast are resource-based heavy industry and manufacturing, which almost account for half of its GDP. This single economic structure can hardly maintain economic growth when its secondary industry is stagnating and even recession. And that is the situation in the northeast. Another problem is the lack of innovation caused by rigid governmental and economic system. Governmental institution still dominates the allocation of market resources. Specifically, state-owned enterprises are the main force in the market, and private economy is weak. While, state-owned enterprises cannot count on to initiate innovation...","city branding; China; Economic revitalization","en","master thesis","","","","","","","","","","","","","",""
"uuid:18e96784-057c-4894-8e56-47f54f853d9d","http://resolver.tudelft.nl/uuid:18e96784-057c-4894-8e56-47f54f853d9d","A Local Time-Stepping Method for Multiphase Flow in Porous Media","Xu, Fanxiang (TU Delft Civil Engineering and Geosciences)","Hajibeygi, Hadi (mentor); Cusini, Matteo (mentor); Rossen, Bill (graduation committee); Dieudonné, Anne-Catherine (graduation committee); Delft University of Technology (degree granting institution)","2018","Simulation of multiphase flow in natural subsurface formations include selection of time-step size, i.e., the discrete snapshots (steps) over which the time-dependent nonlinear process is investigated. The simulation results would naturally depend on the size of the discrete time step, according to the order of accuracy of the implemented numerical scheme. For accurate analyses the required time steps might be needed to be very small, which then leads to very costly simulations, which are often times impractical in real-world simulation applications. Taking coarse-scale time-step sizes can reduce the computational costs, however, it results in lower simulation accuracy. Note that a common simulation practice is to take constant time-step everywhere in the computational domain. To resolve this challenge, this MSc thesis report presents a novel local time-stepping (LTS) method for multiphase flow in porous media. In this method, different time-steps can be applied in one computational domain; allowing for employing small time steps in sub-domains with higher sensitivity to the time step size and bigger time steps elsewhere. The LTS method is developed for all types of sequentially-coupled and fully-coupled simulation strategies. For all of these developments, the interfacial flux continuity is the key requirement to connect the sub-domains of different time zones. The fluxes chosen for the inner stages of the coarse time-step are consistent with the chosen simulation strategy. More precisely, in the case of the implicit-pressure-explicit-saturation (IMPES) method these fluxes are lagged in time (explicit), while for the sequential implicit and fully implicit (FIM) methods they are calculated at the current (implicit) time-step. For implicit transport method, the refined zone partition matrices are developed to algebraically form the refined zone Jacobian matrix and refined zone residual vector. The numerical results show that only a fraction of the domain can be simulated with small time steps; while the rest can be simulated at a bigger one. Local time-stepping method provides accurate simulation results compared with the fine-scale time-step simulation results for all three simulation strategies. Specially, the local time-stepping for FIM simulations, which is the mostly common commercial-grade simulation approach, can preserve the accuracy of the results and also the computational efficiency. For the studied cases, the computational efficiency gain of LTS for sequential implicit method is not as significant as that of the FIM. To exploit full adaptivity in simulation, as presented in Appendix B, one can directly apply the developed method of this thesis to adaptive implicit method (AIM); where sequential and fully implicit coupling approaches are applied in different sub-domains of the reservoir. Overall, LTS casts a promising approach to optimize accuracy-efficiency tradeoff when it comes to time step selection.","Local Time-Stepping; Flux Continuity; Fully Implicit Method; IMPES; Sequential Implicit","en","master thesis","","","","","","","","","","","","Applied Earth Sciences","",""
"uuid:885f741c-b474-4df6-bf8d-2fff08f66935","http://resolver.tudelft.nl/uuid:885f741c-b474-4df6-bf8d-2fff08f66935","Extending Structuralism: A campus in Centraal Beheer","Xu, Xiaoyu (TU Delft Architecture and the Built Environment)","Meijers, Lidy (mentor); Spoormans, Lidwine (mentor); Koopman, Frank (mentor); Nevzgodin, Ivan (mentor); Delft University of Technology (degree granting institution)","2018","","","en","master thesis","","","","","","","","","","","","Architecture, Urbanism and Building Sciences","",""
"uuid:fb494040-862b-4040-a36f-a10594a42feb","http://resolver.tudelft.nl/uuid:fb494040-862b-4040-a36f-a10594a42feb","Data analysis, processing and interpretation from different sources: satellites, ground sensor, citizens measurements and municipalities, to fight against building subsidence","Dimopoulos, Giorgos (TU Delft Architecture and the Built Environment); Garcia Gonzalez, Gabo (TU Delft Architecture and the Built Environment); Marx, Danny (TU Delft Architecture and the Built Environment); Micha, Ioanna (TU Delft Architecture and the Built Environment); Xu, Yixin (TU Delft Architecture and the Built Environment)","Lemmens, M.J.P.M. (mentor); Voûte, R.L. (mentor); Boelhouwer, P.J. (mentor); Delft University of Technology (degree granting institution)","2018","Every day, terabytes of information is generated, filling storage devices around the world. However,the human brain have limited capacities to read and understand raw data from a computer screen.That is why data specialists need to ingeniously create better ways to display, process and analyzemassive amounts of data.Our research project is not about avoiding subsidence, not even about cracks on buildings; it ispurely data analysis and interpretation. This study will help professionals understand and fightagainst building subsidence. Our task was to create, manipulate and make sense of charts like theone below (a real line graph from InSAR data), then translate them into useful information forstakeholders in the local, national and global community.The aim of the project was to understand if ground sensor technologies are comparable to othersources of information. In our analysis different strategies to analyze building subsidence wereimplemented, e.g. homogeneous subsidence, heterogeneous subsidence and for water levels,interpolation and cross correlation methods. In addition, other techniques like sensor fusing wereimplemented to compare data from different sources.As a result from all these strategies, we can say that the water level sensors placed in our researchbuilding, have a high similarity with citizens and municipality data. In contrast, InSAR data is notcomparable with the subsidence sensors placed in the building because they have differentreferences and the period of study was too short to get accurate results from satellite data. Finally,an idea for future implementation strategies was proposed. On this idea, measurements of levelscan be carried out taking as a reference the NAP level and comparing the subsidence between ahealthy-foundations building and another one with wooden-piles foundation.","","en","student report","","","","","","","","","","","","Geomatics","Synthesis Project 2018",""
"uuid:8ad7f7f7-0aca-4b19-bfc6-f7e41495d86a","http://resolver.tudelft.nl/uuid:8ad7f7f7-0aca-4b19-bfc6-f7e41495d86a","Experience the History: An exhibition for Océ small format printing","Xu, Meng (TU Delft Industrial Design Engineering)","Boru, Asli (mentor); Keller, Ianus (mentor); Brouwers, Jolijn (mentor); Delft University of Technology (degree granting institution)","2017","An exhibition in a company museum, Océ museum, is designed in this graduation project.
Océ is a global leader in digital imaging, industrial printing, and collaborative business services. The Océ museum was founded since 1983 to show the company history to its customers, fellow workers, and the interested public. In 2015, Océ opened the Customer Experience Center where visitors can experience the latest products and services of Océ.
The assignment for this project is to design the presentation for Océ small format printing to connect the Customer Experience Center and to achieve a marketing effect. The research was done on the aspects of company, the market of small format printing, and museum in order to gather content about what can be presented for marketing and get inspired on how to present the content for a better museum experience. Through iterating from content to experience, a concept was proposed to let visitors experience the company’s growth in the changing world.
The concept connects Océ museum with the Customer Experience Center by showing the evolvement of Océ’s positioning in the small format market, from office copying to production printing. The marketing effect is achieved by showing the evolvement of copying and printing facilitated by Océ’s remarkable products and unique technologies from diazo copying in the museum to inkjet printing in the Customer Experience Center. Visitors will experience the evolvement personally and have a time travelling from 1960, 1981, 1997 to the current. This experience enables visitors to have a comprehensive view on the company’s development and to witness its perseverance in technology developing and its tradition of innovation.
To validate the concept, the experience of copying by Océ 155 and with diazo copying technology in 1960 is detailed. Tests are done to evaluate this experience and recommendations for further develop are put forward based on the test results.
Nowadays, the rising penetration of smartphones andthe important roles of them in people’sdaily life make the smartphones an ideal medium to conduct paymenttransactions. The smartphones are capable tostore everything that would normally be carried in a physical wallet andalso allows the users to make payments anytime and anywhere. The potentialadded-values of mobile payments, such as generating new revenues, obtaining newusers, increasing user stickiness attracted different players to expand theirbusinesses to the mobile payment services, including financial institutions,mobile network operators, mobile device manufacturers, trusted third partyproviders. To compete in the market, they explored differenttechnologies and business models which resulted in the complexity and dynamicsof the mobile payment market. Consequently, mobile payments have only become astandard practice in a few countries. In termsof proximity payments, NFC is widelyviewed as one of the most promising technologiesdue to its security features, compatibility with the existing financialinfrastructures, and ease of use. In the Chinese market, compared with QR code,NFC was first introduced and supported by various players. However, the Chinesemobile proximity payment market has become the largest and fastest-growingmobile proximity payment market in the world in few years by utilising QR code.The market is highly concentrated withAlipay and Tenpay which are QR code-based mobile payment platforms. In otherwords, QR code overtook NFC and became the most popular mobile proximitypayment technology in China.
Considering this phenomenon, the main researchquestion in this study is set as""why did QR code-based mobile payments overtake NFC and achieve a dominantposition in the Chinese market?"". In orderto answer this question, the research work is conducted in three steps.Firstly, a historical review of the Chinese mobile proximity payments isperformed to identify the mainstream mobile proximity payment solutions basedon QR code and NFC technologies and corresponding business models adopted inthe Chinese market. Secondly, a desk research is conducted to determine thebarriers that mobile payment providers and users face towards to QR code andNFC-based mobile payment solutions using a multi-perspectiveframework. To obtain the situation in the Chinese market and also triangulatethe results of the desk research, in-depth interviews are conducted with technical experts and manager from the Chinesemobile payment industry. Lastly, a proposed research model is used to analysethe strategic actions of the mobile payment providers who support differenttechnological solutions, how they develop the mobile payment platforms andfacilitate users’ adoption of their mobile proximity payment services in theChinese market.
In this study, the research model is developed basedon relevant business model, platform andbusiness ecosystem theories. The final research model consists of three connectedperspectives which are platform technology, platform ecosystems and platformservices. It is applied to three Chinesemobile payment platforms, namely, He Wallet, Alipay and QuickPass which have implemented one or several technologicalsolutions based on NFC and QR code technologies. The data for the casestudies is collected from thesemi-structured interviews and the desk research. The results showed that althoughNFC technology was adopted first in the Chinese market, the enablingdevices of both consumers and merchants were not widely ready at that time forNFC technology, but good enough for QR code technology. However, the early NFCadopters (both MNOs and financial institutions) were reluctant to make a huge investment inthe enabling devices to realise the large-scale deployment in the early stagedue to the uncertainties on the technology level and the unclear roles andbenefits on the business aspect. Thereby, they missed the best time to captureuser and develop users' habit. In contrast, Alipay strategically adopted the independent service provider mode to leverage its obtained platformresources and capabilities whichsignificantly contributed the mass adoption of QR code in the Chinese market. DespiteQR code currently dominated the Chinese mobile payment market, it is believedthat NFC has its place in the Chinese mobile payment market as China UnionPayadopted an open platform strategy to incorporateall relevant players into its ecosystemto facilitate the development of NFC-based mobile payments.
The research results in this study are not onlybeneficial to the theoretical research in mobile payments but also useful forthe practical development of mobile payments. From the theoretical perspective,this research provides a comprehensive overview of the characteristics andpotential barriers of four technologicalsolutions based on NFC and QR code technologies. Besides, it developed aresearch model which can be used to interpret the status of a mobile paymentplatform. From practical perspective, itprovides some insights to the mobile payment providers in terms of the technology selection, the design of the businessmodel, the service development and the marketing strategies.","","en","master thesis","","","","","","","","","","","","Management of Technology (MoT)","",""
"uuid:9ae7f8e9-f528-4f93-90f6-30641d0a3ddd","http://resolver.tudelft.nl/uuid:9ae7f8e9-f528-4f93-90f6-30641d0a3ddd","Numerical Simulation of the Interaction of A Membrane with Water with A Free Surface: Simulation of An Experiment by L. Rizos","Xu, Pengpeng (TU Delft Mechanical, Maritime and Materials Engineering)","Wellens, P.R. (mentor); Delft University of Technology (degree granting institution)","2017","In order to collect validation data for the study of the mechanism of fluid-structure interaction (FSI), an lab experiment was conducted by L. Rizos in the towing tank, 3ME,TUDelft in 2016. The concept of the experiment is shown in the figure 1. A cylindrical container is partially filled with water. A small cylindrical oscillator with flexible bottom is placed in the container. The oscillator is driven harmonically by a motor. During the experiment, the deflection of the flexible bottom, the motion of the free surface and the driven force were monitored and recorded. The figure 2 is the photo of the experiment. In order to better understand Rizos’ experiment, a series of researches are conducted in the Section Ship Hydromechanics, which includes analytical simulation and several numerical simulations with different methods. A linear algorithm is developed in this thesis, which applies implicit, monolithic (solving the fluid domain and structure domain simultaneously) and one-step (without iteration) methods. The model of the numerical simulation is shown in the figure 3, a small cylinder with flexible bottom is placed in the big cylindrical container. The two cylinders are partially filled with water and the still water levels are the same. The inner cylinder does not moves up and down as a whole. The oscillation of the whole system is the result of the initial wave elevation in the fluid domain and/or the initial deflection in the structure domain. The result of the numerical simulation is shown in the figure 4. The effect of added mass for a structure submerged in water results in that smaller eigen frequency of the structural vibration. The structure interacts with the ambient fluid, especially the free surface. For a pre-defined initial condition, the influence of the free surface results in the mode dispersion. The numerical periods of this FSI system agrees with the analytical periods. Significant numerical dissipation exists in the 1st order time integration techniques. Thus, the second order implicit Adam Moulton method, i.e., the trapezoidal rule, is implemented to improve the algorithm. in this way, the numerical dissipation is decreased drastically (5% less dissipation after 10 periods) without increasing the computational costs.","fluid-structure interaction; Numerical modelling; Linear model; Monolithic algorithm; one-step process","en","master thesis","","","","","","","","","","","","Offshore and Dredging Engineering","",""
"uuid:743e121a-9934-4d73-9b86-92d6eda6aa21","http://resolver.tudelft.nl/uuid:743e121a-9934-4d73-9b86-92d6eda6aa21","A Potential New Structural Design for Flexible Pavement","Xu, Quanxin (TU Delft Civil Engineering and Geosciences; TU Delft Engineering Structures)","Erkens, S. (mentor); Kasbergen, Cor (mentor); Houben, Lambert (mentor); Farah, Haneen (mentor); van de Wall, A.R.G. (mentor); Delft University of Technology (degree granting institution)","2017","Throughout the history of pavement structure, the parallel layer structure has dominated the structural design of pavements. In other words, the entire road pavement share a uniform thickness design regardless how many lanes there are. However, due to traffic regulations and driving habits, the traffic flow most probably does not distribute evenly on a multi-lane road. Modern pavement design methods usually choose the lane that bears the heaviest traffic load as the design lane to determine the thickness design of the entire pavement. Hence there could be a certain over-design in the less trafficked lanes. This study aims to propose and evaluate a new structural design for flexible pavement by reducing the thickness of asphalt layers of the lightly trafficked lanes.
The traffic data of a real motorway in the Netherlands was analysed, based on which a new pavement structural design of a 3-lane road was established. Two finite element models, for both original and new designs, were established in CAPA-3D to calculate the stress and strain responses under different traffic load combinations. Following the Dutch design method the fatigue and deformation performance predictions of the two pavement designs were executed and compared. The results showed that the new design indeed improve the material cost-efficiency without compromising the performance of the pavement structure.
Taking advantage of the finite element models, a real-life simulation was also applied. The strain output of the simulation was used to calculate the rutting depth following the American design method. Both calculated rutting depth and the deformation output of the real-time simulation supported the earlier conclusions. An extra simulation of truck platooning was briefly executed and discussed as well.
Furthermore, the construction and maintenance feasibilities of the new design were explored. It was proved that the new design can be constructed by the existing equipment and machines. The current maintenance methods and procedures can also be applied to the new design.","Pavement; Structural design; Finite Element Analysis; road construction","en","master thesis","","","","","","","","","","","","","",""
"uuid:efe6c4e1-20c1-40df-898f-aae60df5dc8a","http://resolver.tudelft.nl/uuid:efe6c4e1-20c1-40df-898f-aae60df5dc8a","Packet loss concealment for speech transmissions in real-time wireless applications","Xu, Boliang (TU Delft Electrical Engineering, Mathematics and Computer Science; TU Delft Microelectronics)","Heusdens, R. (mentor); Hendriks, R.C. (mentor); van der Lubbe, J.C.A. (graduation committee); van der Schaar, Hans (graduation committee); Delft University of Technology (degree granting institution)","2017","Packet communication applications cannot guarantee correct delivery of every packet. Congestions and interferences in the network lead to lost packets. However, real-time applications require timely delivery of data or information and always tolerate packet loss to achieve this aim. When some speech packets are lost, packet loss concealment (PLC) is used to replace the missing speech.
In this thesis, after investigating packet loss characteristics in realistic wireless networks and problems in existing PLC algorithms, we propose a new PLC scheme named adaptive PLC, which is composed of three algorithms: odd-even interpolation, waveform similarity matching and silence substitution. Adaptive PLC adjusts the algorithm to use depending on loss situations. Odd-even interpolation recovers the loss by interpolating odd or even samples in a packet. Waveform similarity matching estimates waveform segments from correctly received or already recovered packets. Silence substitution just fills in the missing part by zeros.
The adaptive PLC achieves improvements in speech quality relative to each single PLC algorithm and other existing PLC algorithms.
After preprocessing, large sized data will be subdivided based on octree algorithm to minimize transmission time from server to the client; moreover, accessible to WebGL. A prototype has been developed which enables smooth and timely vario-scale map rendering against heavy user actions such as fast zooming and panning in a short period. Modified prototype program allows query of only relevant data chunks by current viewport position; it prevents repeated loading of same chunks; what is more, repeated transmission of data from outside to GPU is eliminated. A tree structure is embedded at the client side that facilitates retrieve time. Rendering happens every frame; hence the prototype responses to heavy user actions timely. Also, it can obtain coordinates in RD coordinate system by double clicking. After testing the modified program with a 9km by 9km dataset online, exceptional performance is indicated by a high average frame rate (57 fps) and low main memory occupation (with a network speed at 9MB/s). The prototype performance is significant affected by the client network condition; low network speed can decrease the frame rate. For instance, the web service achieved a frame rate of 47 fps at a network speed at 6MB/s.","SSC; WebGL; Web Service; 3D; tGAP; vario-scale","en","master thesis","","","","","","","","","","","","Geomatics","",""
"uuid:d08f7c89-1b3c-4c7a-9c5d-1ed5a8d980bc","http://resolver.tudelft.nl/uuid:d08f7c89-1b3c-4c7a-9c5d-1ed5a8d980bc","Low-Power Readout IC for a PMUT-based bladder scanner","Xu, W.","Pertijs, M.A.P. (mentor)","2017","","","en","master thesis","","","","","","","","2018-01-31","Electrical Engineering, Mathematics and Computer Science","Microelectronics","","","",""
"uuid:b94abc72-3636-4d6e-8ccf-49f21e162496","http://resolver.tudelft.nl/uuid:b94abc72-3636-4d6e-8ccf-49f21e162496","Fabrication of an ultraviolet absorption spectroscopy probe for protein quantification in bioreactors","Xu, D.B.","de Graaf, G. (mentor)","2017","Bioreactors are used nowadays to produce proteins with therapeutical effect that can treat a new range of diseases in humans. Unfortunately, measuring protein concentrations directly inside bioreactors in real time is still an unsolved challenge. This is due the large amount of compounds that can be found inside the bioreactors that interfere with traditional protein quantification techniques. With this, quantifying protein is still highly desired because it would allow more efficient control of the cell cultures and better awareness on the development of the bioprocesses inside bioreactors. A probe system that combines ultraviolet absorption spectroscopy technology with a passive mechanical sieve system is designed and built in this project in order to measure protein concentrations directly inside bioreactors in real time. To fabricate the designed probe, Silicon MEMS fabrication techniques were used in order to reproduce the designed micron-sized structures with precision and reproducibility. Also, using silicon technologies would allow easier design upgrading, different technologies integration and production cost efficiency. The designed and built system showed in preliminary experiments the capability to quantify different protein concentration levels by creating a calibration curve although the obtained signal was low. Consequently, more signal fluctuations caused by noise was present and less accurate signal readings were obtained. Further improvements are required in order to increase the signal levels which would provide more accurate and reliable quantifications. On the filtration aspect, the system showed to successfully block all particles, such as cells, from entering the optical chamber avoiding signal interference in the short term. Further experimentations are required to assess the long-term performance of the filtration system. With this, the development of this project allowed to proof the concept of using a combined system of ultraviolet absorption spectroscopy and mechanical sieves that could enable measuring protein concentration directly inside bioreactors in real time. Consequently, further design and development iterations are required in order to improve technically the system that allow higher signal levels with more accurate quantifications. Also, further experimental tests are required to assess the long term performance of the filtration system.","","en","master thesis","","","","","","","","2022-01-31","Electrical Engineering, Mathematics and Computer Science","Microelectronics","","Electronic Instrumentation","",""
"uuid:6a84f9ae-f6f5-4e86-9dc6-22238eaae9f3","http://resolver.tudelft.nl/uuid:6a84f9ae-f6f5-4e86-9dc6-22238eaae9f3","My move: A service design of moving experience for Ford commercial vehicle","Xu, X.","Stappers, P.J. (mentor); Hao, C. (mentor)","2016","This graduation project was initiated by ID StudioLab, in collaboration with Ford. The goals are to understand deeply about commercial vehicle users' needs especially by using contextmapping method and to design innovative service concept in the area of mobility. This project adopted double diamond service design process, including Discover, Define, Develop and Deliver phases. The target group was decided as movers who are self-employed or work in a small company use van to deliver moving service. Deep insight gained from users, including both clients and movers, is that the tension of distrust relatively prevents positive user experience and emotions of stress and unconfidence occurs during moving. The overall goal of My Move is to build trust between movers and clients, respectively to let movers be confident and let clients be relaxed. My Move, as the final design, is a service provided by Ford which makes the connection between clients and professional movers. Ford, as a mediator between these two parties, provides service with features of integrated moving information, real-time tracking, instant notifications, (un)loading checker and editor, online platform and off line Pit stop station for leasing van and delivering box with RFID tags.","service design; movers; user experience; commercial vehicle","en","master thesis","","","","","","","Campus only","","Industrial Design Engineering","Industrial Design","","Design Conceptualization and Communication","",""
"uuid:94b13408-0918-4140-8c7b-2dba6b2420c5","http://resolver.tudelft.nl/uuid:94b13408-0918-4140-8c7b-2dba6b2420c5","Determine activity based on the classified identity of users by using Wi-Fi monitoring","Groeneveld, IJ.D.G.; Sulzer, R.; Theocharous, E.; Tryfona, M.S.; Willems, O.T.; Xu, Y.","Quak, W. (mentor); van der Spek, S.C. (mentor); Valks, B. (mentor)","2016","The Wi-Fi technologies are used in everyday life on numerous applications that detect the crowd information for commercial, security and other reasons. The Wi-Fi monitoring can be used for tracking people when they are moving along different access points. The results from the Wi-Fi monitoring can provide the location of the users in an area and therefore, useful information can be extracted. The goal of this project is to recognize the activity of different users for different sessions of a Wi-Fi network. The Wi- Fi dataset that is used, is acquired from the Wi-Fi network of the Delft University of Technology (TU Delft). Initially, the estimation of the users’ occupation is determined with the use of a Markov model with the information that is derived from the Wi-Fi dataset. Their possible identity is used, in order to estimate the activity that a user is probably doing at a specific location of the research area. The results on the use of the research area, are calculated and visualised in different spatial levels, campus, building and floor level. The use of the building complex of the TU Delft Campus, is examined during irregular hours, to allow efficient real estate management and provide security solutions.","Localisation; Markov model; Activity; Real Estate Management; TU Delft campus; Wi-Fi monitoring","en","student report","","","","","","","","","Architecture and The Built Environment","Geo-information Technology","","Geomatics for the Built Environment","TRACK-id",""
"uuid:f59b08e4-c3e9-400c-9403-f8129cd5b578","http://resolver.tudelft.nl/uuid:f59b08e4-c3e9-400c-9403-f8129cd5b578","Topology optimization of lithium ion batteries: How to maximize the discharge capacity by changing the geometry","Xu, T.","Langelaar, M. (mentor); Van Kempen, F. (mentor); Van Keulen, F. (mentor)","2015","Discharge capacity is an important factor that determines the performance of lithium ion battery. The internal resistance of the electrodes influence the discharge capacity. As the electrode geometry influences its resistance, topology optimization can be applied to determine the electrode shape such that it has a minimal internal resistance and thus obtain the maximum discharge performance. The influences of different design parameters have been analysed by means of numerical case studies. Several penalty techniques have been used to make the final topology more realistic and easy to manufacture. The discharge capacity and capacity fade under different discharge current, different design structures and different optimization constraints are imposed and analysed. A three dimensional electrode model based on the topology optimization is built and simulated. The comparison between different optimization methods has been studied.","topology optimization; batteries","en","master thesis","","","","","","","","2018-10-15","Mechanical, Maritime and Materials Engineering","Precision and Microsystems Engineering","","Structural Optimization and Mechanics","",""
"uuid:dfe642e3-2bb4-4126-89b3-1a07b1fe7014","http://resolver.tudelft.nl/uuid:dfe642e3-2bb4-4126-89b3-1a07b1fe7014","Metastable Beta Titanium Alloys: Tuning the Beta Phase Stability and Low-Temperature Martensitic Transformation of Metastable Beta Titanium Alloys","Xu, L.","Van der Zwaag, S. (mentor); Xu, W. (mentor); Lu, Q. (mentor)","2015","This research focuses on the stability of three metastable ? titanium alloys – Ti-10V-1Fe-3Al (Ti-1013), Ti-10V-2Cr-3Al (Ti-102Cr3) and Ti-10V-2Fe-3Al-B (Ti-1023B). In the first stage of the work, new ?+(?+?) heat treatment schemes were designed on the basis of Thermo-Calc® simulations and previous research work and carried out to such an extent that the ? phase stability is tuned to the right level and a sufficient amount of retained ? phase is obtained at room temperature available for further transformation. At the second stage, the effectiveness of the thermal driving force in triggering a martensitic transformation in the retained ? phase was investigated. Both in-situ and ex-situ transformations were studied via DSC and further quenching in self-made cooling baths, respectively. The starting temperatures of low-temperature martensitic transformations were determined for each alloy. It was found that the low-temperature martensitic transformation for the three alloys was of an isothermal character. Through XRD testing, the phases of Ti-1013 before and after low-temperature martensitic transformation were determined; as in the commercial Ti-10V-2Fe-3Al (Ti-1023) alloy, the type of martensite formed in response to quenching from the two-phase region is ?’’ instead of ?’ martensite, due to oversaturation of the martensite. EPMA testing proved the formation of Martensite-Free Zone (MFZ) observed in the case of Ti-102Cr3 when quenched to a temperature just below the starting temperature of the low-temperature martensitic transformation does not relate to the diffusion behavior of alloying elements. Electrical Discharge Machining (EDM) was found to be detrimental in this research as the machining process changed the designed microstructure of the three metastable ? titanium alloys. Finally, a proposal is made to produce tailored ?+? titanium metallic composite via SPS.","Metastable Beta Titanium Alloys; Beta Phase Stability; Martensite-Free Zone; Low-Temperature Martensitic Transformation","en","master thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","Materials Science and Engineering","","Materials Science and Engineering","",""
"uuid:721209c1-b10b-413b-ac08-91201c89ee23","http://resolver.tudelft.nl/uuid:721209c1-b10b-413b-ac08-91201c89ee23","Implementation of in-situ monitoring techniques for power reduction in smart sensors","Xu, G.","Van der Meijs, N.P. (mentor); Gemmeke, T. (mentor)","2015","Nowadays, smart sensors are widely used in a variety of application domains, such as telecommunication, health care, cars, mobile phones, smart cities. Because of limited battery capacity, low-power design is required for smart sensors. Low-voltage operation is a key leverage to reduce power consumption in smart sensors. However, uncertainties due to process, voltage and temperature variations or random fluctuations gain in relevance when operating in the near-threshold range. Hence, monitoring of the actual silicon behavior is crucial to lowering supply voltage while preserving reliable operation. An interrupt-based in-situ monitoring approach is proposed in this thesis. This approach uses an interrupt service routine to stimulate the critical paths on the chip. By monitoring the timing of the exercised paths, a warning signal is generated to steer the control of reliable supply voltage levels. This approach is developed, validated and applied on an ARM-based processor. Finally, a 10 mV supply voltage margin is achieved based on measurements in the near-threshold range. In addition, reliable operation is verified by running different self-checking codes over multiple dies while varying the environmental conditions.","","en","master thesis","","","","","","","","2019-10-01","Electrical Engineering, Mathematics and Computer Science","Microelectronics & Computer Engineering","","Electrical Engineering","",""
"uuid:8fd6a9ef-3dfb-4bd1-b54e-44d5b2cca973","http://resolver.tudelft.nl/uuid:8fd6a9ef-3dfb-4bd1-b54e-44d5b2cca973","Spatial model-aided indoor tracking","Xu, W.","Liu, L. (mentor)","2014","In order to address the problem of indoor pedestrian tracking, this thesis reports a research on spatial models' ability to reduce tracking error of a WiFi positioning system. There are three main objectives in this research. First, it is to build a suitable spatial model for tracking. Second, it is to develop a tracking algorithm that can make full use of the spatial model. Last, the tracking algorithm should be tested in a live environment. Based on literature study, a grid-based spatial model is chosen to be built because it is easy to design and maintain, has high flexibility, has accurate location data and is powerful for computation. The thesis explores various geometric, topological and semantic features of the grid model and select out the most useful features upon tracking purposes. Among geometric features, coordinate, buffer, orientation vector and Euclidean distance are used. Among semantic features, space, obstacle, and door are employed. Among topological features, the difference between straight-line distance and shortest path distance is chosen. We develop the tracking algorithm combining multiple tracking techniques. In addition to the spatial model and WiFi positioning system, the algorithm also includes magnetometers and grid filters. The former one measures the orientation of a pedestrian. The latter one allows integrating all selected features of the grid model with the measurements from both the WiFi positioning system and the magnetometer to compute the location recursively. To test the algorithm's performance, we built a tracking system with database, web service and mobile client. Several experiments are carried out using the system in a real environment. The experiment results show that the algorithm is able to determine locations at reasonable places (in the correct space, outside obstacles and connected to the previous location) and derive the accurate moving direction of a pedestrian.","spatial model; indoor tracking; grid filter; WiFi positioning system","en","master thesis","","","","","","","","","Architecture and The Built Environment","Geomatics","","Geomatics for the built environment","",""
"uuid:da5e8895-b950-46b0-b33f-0293d7cfa57c","http://resolver.tudelft.nl/uuid:da5e8895-b950-46b0-b33f-0293d7cfa57c","DaRen: A multi-purpose 3D indoor navigation application","Van Winden, K.B.A.; Onrust, B.; Van der Laan, E.; Kruminaite, M.; Makri, A.; Xu, W.; Liu, H.","","2013","This is the final report of the 2013 Synthesis Project of MSc Geomatics. The research is about the possibilities of creating the DaRen application: ""A multi-purpose 3D indoor navigation application"".","3D; indoor; navigation; application; geomatics; final; report","en","student report","","","","","","","","","Architecture and The Built Environment","Geomatics","","","",""
"uuid:47957f9e-8ee2-4c00-9cb8-9bbd49b7c7f9","http://resolver.tudelft.nl/uuid:47957f9e-8ee2-4c00-9cb8-9bbd49b7c7f9","Kinetics of Wüstite Formation and Reduction of Manganese alloyed Steel","Xu, J.","Sloof, W.G. (mentor)","2013","The oxidation and reduction kinetics of a 1.7 wt.% Mn steel alloy with 0.1 wt.% C was studied in different ?CO?_2/CO mixtures and at different temperatures. The external iron oxide growth, the internal alloying element oxide formation and the reduction of iron oxides were observed with thermogravimetry (TG). The oxidation at 750 ? follows a logarithmic growth rate law, which suggests that transport of electrons from the metal through the oxide determines the kinetics. However, the oxidation rate of a linear growth at 950 ? obeys a linear growth rate law, which suggests that the dissociation of ?CO?_2 into CO and adsorbed oxygen atoms or ions determines the kinetics. The kinetics of the reduction of external iron oxide by hydrogen follows a First-Order model. A Wüstite scale with internal Manganese oxide was formed during the thermal oxidation in different ?CO?_2/CO mixtures. After reduction with H_2at 950 ?, an iron layer with internal Manganese oxide was obtained at the surface of the steel. The depth of the internal Manganese oxide zone increased during the reduction.","manganese alloyed steel; oxidation; reduction; kinetics","en","master thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","Materials Science & Engineering","","","",""
"uuid:6579ee97-6315-48ed-a7f1-1fca8870f130","http://resolver.tudelft.nl/uuid:6579ee97-6315-48ed-a7f1-1fca8870f130","Low Temperature Fabrication of SiO2 Films Using Liquid Silicon","Xu, Y.","Ishihara, R. (mentor)","2013","In this study, a new fabrication method was implemented to convert liquid silicon into silicon dioxide films through non-vacuum and roll-to-roll compatible processes at low temperatures. The electrical characterization of SiO2 films made from liquid silicon was reported for the first time.","print process; liquid silicon","en","master thesis","","","","","","","","2014-12-31","Electrical Engineering, Mathematics and Computer Science","Microelectronics & Computer Engineering","","","",""
"uuid:83fa4700-fe20-4501-8394-7bb870fe83a5","http://resolver.tudelft.nl/uuid:83fa4700-fe20-4501-8394-7bb870fe83a5","The Culture of Care - Rijndam Rehabilitation Centre, Rotterdam","Xu, K.","Zeinstra, J. (mentor); Alvarez, L. (mentor); Parravicini, M. (mentor)","2013","","interior; rehabilitation Center","en","master thesis","","","","","","","","2013-06-27","Architecture","Interiors,Buildings & Cities","","Culture, Identity and Sociability","",""
"uuid:1a42ee08-6bb0-4e95-b23f-e75cd42d2f7c","http://resolver.tudelft.nl/uuid:1a42ee08-6bb0-4e95-b23f-e75cd42d2f7c","Are we on the same page? Comparing professional practices between industrial designers and mechanical engineers in perceptions and procedures during product development","Xu, C.","Badke-Schaub, P. (mentor); Coimbra Cardoso, C.M. (mentor)","2012","The objective of this research is to find differences between industrial designers and mechanical engineers in perception and procedures during product development. This research has focused on cooperation between multidisciplinary teams’ participants - both industrial designers and mechanical engineers, because current innovation processes require more and more cooperation between many different disciplines. Multidisciplinary cooperation is a valuable research topic to bring more productivity and better understanding to team members. And one of the most frequently seen cooperation in product development projects is the cooperation between the industrial design and mechanical engineering disciplines. Differences between these two disciplines in professional practice are in need of research. Doing this research can provide analyzed results which may reveal the fundamental causes and phenomena. It can provide insights which can help improve performance in projects involving these two disciplines for later cooperation. During this research, eight face-to-face interviews have been performed. Four professional industrial designers and four mechanical engineers have participated in this research. One industrial designer and one mechanical engineer are from the same design agency or organization which has been involved in multidisciplinary projects. Some interesting findings and results have come out. Trainings have been fundamental in forming these professionals’ way of thinking, their way of problem solving and their way of carrying out their skills. Trainings contain two parts - academic training and career training. Academic training influences their knowledge foundation, while career training influences their current approaches on projects with the other discipline. Self-perception and perception of the other discipline have the consistency that designers focus more on shaping and forming the outside of products while engineers focus on functions inside of the products. Industrial designers are more familiar with iterative approaches to diverge and converge in ideas with the aim of getting closer to an optimal solution; Mechanical engineers are often taking a straight-line approach where one solution is worked out in great detail, with the aim of meeting clients/customers’ requirements. Industrial designers see the value of a multidisciplinary team in helping them realize their concept or idea, allowing them to see real progress into prototyping, or even into production. Also they emphasized on how it can improve the quality of products’ credibility. Mechanical engineers see the value of a multidisciplinary team at the social level, helping them learn to communicate with industrial designers. With some success and failure projects which interviewees had experienced, expectations from both sides have been mentioned. The ideal scenario for a working environment, how the working procedures may be improved, and how to solve time and budget limitations are all elaborated. Interviewees also have put some recommendations forward. Their recommendations cover communication issues and issues caused by mutual perception bias. Differences and commonalities of these two disciplines, issues that occur during multidisciplinary cooperation, and new insights have all been written with a general conclusion. This report notes several limitations of its research, and some recommendations for further study will be presented at the end.","industrial design and mechanical engineering; multidisciplinary cooperation; differences; perception; product development; issues; empirical research; professional practice","en","master thesis","","","","","","","Campus only","","Industrial Design Engineering","Industrial Design","","Master of Science Strategic Product Design","",""
"uuid:702b94e8-903d-4794-8e53-bb5b8da0917a","http://resolver.tudelft.nl/uuid:702b94e8-903d-4794-8e53-bb5b8da0917a","Design and Implementation of Constraints for 3D Spatial Database: Using Climate City Campus Database as an Example","Xu, D.","Van Oosterom, P.J.M. (mentor); Zlatanova, S.Z. (mentor)","2011","Nowadays the field of geo-information is undergoing major changes, and the transition from 2D to 3D is having a major influence. A significant amount of 3D datasets are stored in the database. Experts are aware that new quality control mechanisms need to be built into the database systems in order to secure and guarantee high-performing data. Constraints are effective in providing solutions needed to avoid errors and enable maintenance of data quality. Whereas constraints for 2D geographic datasets have already been the subject of several research projects, studies into 3D geo-data constraints are largely unexplored. This thesis research discovers a new approach to model, conceptualise and implement 3D geo-constraints which can function in the database. At the outset, constraints can be formulated using natural language. As natural language is subjective and varies between individuals, expressions can be ambiguous and can easily cause confusion. So spatial constraints are abstracted using geometry that depicts the exact shape, and also topology that reveals the spatial relationship between geometries. This step makes the meaning of a constraint clearer to others. Furthermore, using standardised UML diagrams and OCL expressions, geo-constraints can be formalised to an extent that not only humans, but also machines can understand them. With model-driven architecture supported by various softwares, OCL expressions can be automatically converted to other models/executable codes (e.g. PL/SQL) just by a few clicks. And with small modifications, database triggers can be formulated to carry out constraints check. A database including various topographic objects (e.g. buildings, trees, roads, grass, water-bodies and terrains) is used as a study case to apply the discovered approach. During this research, a first attempt to formulate 3D geo-constraints in OCL has been made. These expressions can be tested and translated to other models/implementations when the OCL standard is extended with spatial types and operations. In the implementation stage, the current 3D functions in Oracle Spatial database are found to be insufficient. A new 3D function using existing 2D functions - plus additional code relating to computational geometry - has been developed by the author to bridge the gap. Based upon this function, a large group of spatial constraints which apply to objects in 3D space can be checked. Bentley Map and Python IDLE are used to test the performance of constraints as well as the visualisation of warning messages to clients. Database error messages are immediately displayed on the front-ends when a modification that does not satisfy a constraint is attempted to commit to the database. During the case study, new classes of constraints are also discovered. They are higher-level constraints, parameterised constraints, constraints allowing exceptional instances, extra-check rules to detect conflicting constraints and constraints relating to multi-scale representations.","3D spatial; constraints; database","en","master thesis","","","","","","","","2011-09-15","OTB Research Institute for the Built Environment","GIS-technology","","MSc Geomatics","",""
"uuid:bad96e05-4c19-4560-ab7e-dc5595be6164","http://resolver.tudelft.nl/uuid:bad96e05-4c19-4560-ab7e-dc5595be6164","Master of Science","Xu, M.","Bier, H. (mentor); Rommens, O. (mentor)","2010","","Metaball","en","master thesis","","","","","","","","2012-01-01","Architecture","Architecture","","Border Conditions","",""
"uuid:80ea30e9-11c3-4e7e-b250-7de6015f4744","http://resolver.tudelft.nl/uuid:80ea30e9-11c3-4e7e-b250-7de6015f4744","Charge Domain Interlacing CMOS Image Sensor Design","Xu, Y.","Theuwissen, A. (mentor)","2009","This thesis presents a CMOS image sensor which can implement the charge domain interlacing principle. Inspired by the shared amplifier pixel structure and based on a pinned photodiode four transistor (4T) structure, two innovative pixel designs combined with two different readout directions are presented. These novel pixels are designed to fit the charge domain interlacing principle, which used the charge binning technology in the field integration mode of interlaced scan to improve the signal-to-noise ratio of the sensor. To realize this working principle and compared it with other working modes, a programmable universal image sensor peripheral circuit is designed for controlling and driving the pixel array in the most flexible and most efficient way. As a result, the designed sensor can be used not only in the progressive scan mode, frame integration interlaced scan, and voltage domain interlacing mode but also in the charge domain interlacing mode. This is a very unique feature for CMOS image sensors, and without the shared pixel concept, charge domain interlacing was only possible with CCDs. The proposed image sensor is implemented in TSMC 0.18um 1P6M CMOS technology. Some preliminary measurement results of the chip are shown to prove the functional correctness of the image sensor.","CMOS image sensor; charge binnning; interlaced scan","en","master thesis","","","","","","","","2009-09-02","Electrical Engineering, Mathematics and Computer Science","Microelectronics & Computer Engineering","","","",""
"uuid:9e21bbb7-d034-4f10-8a28-3674187a0e59","http://resolver.tudelft.nl/uuid:9e21bbb7-d034-4f10-8a28-3674187a0e59","C-V profiling of ultra-shallow junctions using a buried layer with stepped doping","Xu, C.","Nanver, L.K. (mentor); Popadic, M. (mentor)","2009","The paper investigates two-sided capacitance-voltage (C-V) technique for application in doping profile characterization of Si ultra shallow p+-n junctions. Stepped doping profile in the n region is designed for the accurate determination of xn0, a crucial parameter for the extraction of the doping profile in the p region. Medici simulations are carried out for the C-VR relationships of the p+-n and n-Schottky junctions with the same step-like n profile. The xn0 can be determined with an accuracy of 1.7 nm by a criteria developed in this work. And the doping profile in the p+ doped region can finally be extracted and shown to be in good agreement with the Medici simulation results.","two-sided junction; c-v; ultra-shallow junctions","en","master thesis","TU Delft, Electrical Engineering, Mathematics, Computer Sci, Microelectronics","","","","","","","","Electrical Engineering, Mathematics and Computer Science","","","","",""
"uuid:156862db-0e26-4c1b-9432-3ed1a413742d","http://resolver.tudelft.nl/uuid:156862db-0e26-4c1b-9432-3ed1a413742d","Applying Public-Private-Partnership to Chinese Subway Infrastructure","Xu, S.","Ten Heuvelhof, E.F. (mentor); De Jong, W.M. (mentor); Stead, D. (mentor)","2008","","","","master thesis","","","","","","","","","Technology, Policy and Management","","","","",""