"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:d4c7dc15-dfda-4790-a627-5a701ff0b5f1","http://resolver.tudelft.nl/uuid:d4c7dc15-dfda-4790-a627-5a701ff0b5f1","Develop an interface for model-informed prototyping of HAI interactions","Zhou, Jiayi (TU Delft Industrial Design Engineering)","Murray-Rust, D.S. (mentor); Mehrvarz, M.M. (mentor); Tsiakas, K. (graduation committee); Delft University of Technology (degree granting institution)","2024","As AI technology continues to advance, there's a growing need to integrate it into UX design. However, AI's unique characteristics do not seamlessly align with current design tools and mastering the technical aspects for designers is a significant challenge. The project goal is to develop a tool based on a developed semi-formal representation for Human-AI (HAI) interactions, which uses a set of communicative acts1 to specify the communicated information between users and AI models as exchanges of messages.
The project followed an iterative prototyping method across 4 phases. The Pre-Phase aimed at testing communicative acts with design students using a use case (""CV-Screening"") and paper materials. At the same time, it also expected to get insights on the data structure and develop the specific design considerations based on those for the Model-Informed Prototyping (MIP),
Phase 1 explored effective workflows of the digital prototype to present communicative acts by following the design considerations from the Pre-Phase and using the low-fidelity digital prototype in Figma. The use case in this phase was the same as that in the Pre-Phase.
In Phase 2, based on insights from the last two phases, there was a high-fidelity prototype in Figma which was inspired by the user journey map. It was used to assess if the design output achieved the design goals and considerations, and it helped the final test materials work better.
The Final Phase utilizes the refined digital prototype for the final test which had the same goals as that in Phase 2, providing important insights for future development.
The final output of the project is a partial prototype of a digital tool designed to facilitate the early stages of human-AI interaction design. Grounded in the principles of communicative acts and human-centered design, this tool assists designers during the Ideation stage of Design process. It achieves this by visualizing the roles, data, and information involved in the process of information exchange during Human-AI Interactions. The goal is to enhance efficiency and ease in designing these interactions.","Human-AI interaction Design; Model-Informed Prototyping; Iterative prototyping method; Communicative acts; UX Design Tool","en","master thesis","","","","","","","","","","","","Design for Interaction","",""
"uuid:6ef24cf8-2dc5-4665-b581-a7c01a71f5dd","http://resolver.tudelft.nl/uuid:6ef24cf8-2dc5-4665-b581-a7c01a71f5dd","The effects of ionic strength and surface charge on O/W emulsion fouling of ceramic membranes quantified via DLVO and XDLVO models","Zhou, Hanxiao (TU Delft Civil Engineering & Geosciences)","Heijman, Sebastiaan (mentor); Chassagne, C. (graduation committee); Tanis, M.B. (graduation committee); Qin, G. (graduation committee); Delft University of Technology (degree granting institution)","2023","Large amounts of oily wastewater which included oil-in-water (O/W) emulsions, also known as produced water (PW), were produced in tandem with the enhanced oil recovery (EOR). Ultrafiltration (UF) was an effective and economic method to separate micron-sized O/W emulsions, while the membrane fouling limited its development. Understanding the fouling phenomena was essential to enhance the efficiency of membrane filtration for oil-water separation, hence this paper investigated the influence of different salinity (1 mM, 20 mM and 100 mM) and types of surfactants on the fouling of the alumina (Al2O3) membrane and the silicon carbide (SiC) deposited membrane filtrating 500 mg/L O/W emulsions with mean droplet sizes of approximately 4 ~ 7 μm, and the UF with the constant flux of 80 LMH and the crossflow velocity of 0.59 m/s was conducted. Sodium dodecyl sulfate (SDS, anionic), alkyl polyglycoside (APG, nonionic), and cetyltrimethylammonium bromide (CTAB, cationic) were chosen in this study due to the frequent use in EOR, and the N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (DDAPS, zwitterionic) was selected because of its low tendency to foul at high salt concentrations.
Derjaguin-Landau-Verwey-Overbeek (DLVO) and the extended DLVO (XDLVO) models were used to quantify the membrane-oil droplet and deposited oil layer-oil droplet surface interaction. The results showed that the SiC-deposited membrane had less membrane fouling and irreversible fouling resistance compared with the Al2O3 membrane when filtrating O/W emulsions stabilized with SDS, APG or DDAPS. The DLVO model estimated emulsion fouling propensity to rise with increasing salinity when dealing with SDS, APG or DDAPS-stabilized O/W emulsions, while CTAB-stabilized emulsion fouling propensity for the SiC-deposited membrane would decrease with the higher salinity.
ERA5. However, no obvious pattern differences are shown between the different CMIP6 GCMs. Persistent challenges stem from data availability and numerical inconsistencies, necessitating enhancements in both the CMIP6 models and the WAM2layers code.
This research is on an accelerating wing with ground effect. The airfoil representing the front wing is from a real F1 car, the Tyrrell 026. Prediction of downforce and flow field in steady phase was done by conformal mapping (potential flow theory), SST k−ω and 2D-DES CFD simulation.
A force and PIV measurement was done to investigate the dynamic flow behaviour.
The connection between force and flow field was discussed, considering the measured residual force and the added mass force. A conclusion is drawn with suggestion on setting the optimal clearance of an F1 car’s front wing on track, to improve the racing performance of the car.","PIV (particle image velocimetry); Ground Effect; Accelerating Flow","en","master thesis","","","","","","","","","","","","Mechanical Engineering | Energy, Flow and Process Technology","",""
"uuid:dd3c4287-ac18-4e9e-852d-24c3bf584dc7","http://resolver.tudelft.nl/uuid:dd3c4287-ac18-4e9e-852d-24c3bf584dc7","Liveness checking of Streamlined Blockchain Consensus","Zhou, Yanzhuo (TU Delft Electrical Engineering, Mathematics and Computer Science; TU Delft Distributed Systems)","Decouchant, Jérémie (mentor); Kulahcioglu Ozkan, Burcu (graduation committee); Pouwelse, J.A. (graduation committee); Delft University of Technology (degree granting institution)","2023","Byzantine consensus protocols are designed to build resilient systems to achieve consensus under Byzantine settings, maintaining safety guarantees under any network synchrony model and providing liveness in partially or fully synchronous networks.
However, several Byzantine consensus protocols have been shown to violate liveness properties under certain scenarios. Existing testing methods for checking the liveness of consensus protocols check for time-bounded liveness violations, which generate a large number of false positives.
In this thesis, for the first time, we check the liveness of Byzantine consensus protocols by the temperature and lasso detection methods and precisely detail ad-hoc system state abstractions that should be used to test these algorithms.
We provide a theoretical analysis of the recently-published safety and liveness attacks and whether the existing test method is able to detect them.
To investigate the issues, we focus on the streamlined blockchain consensus, particularly the HotStuff protocol family, which has been recently developed for blockchain consensus. Among these protocols, the HotStuff protocol itself is both safe and live under the partial synchrony assumption, whereas 2-Phase Hotstuff and Sync HotStuff protocols can violate liveness in subtle fault scenarios.
We implemented our liveness checking methods on top of the Twins automated unit test generator to test the HotStuff protocol family and explored the scenarios with message delay.
Our results indicate that our methods successfully detect all known liveness violations and produce fewer false positives than the bounded liveness checks.","Liveness checking; Byzantine Consensus; HotStuff protocols; Twins","en","master thesis","","","","","","","","","","","","Computer Engineering | Distributed Systems","",""
"uuid:1534f971-06aa-45ac-8c95-1504aa6878cb","http://resolver.tudelft.nl/uuid:1534f971-06aa-45ac-8c95-1504aa6878cb","Control for Bipolar DC Microgrid and DC/DC Bidirectional Converter in Energy Access Context","Zhou, Xiaochuan (TU Delft Electrical Engineering, Mathematics and Computer Science)","Qin, Z. (mentor); Mackay, Laurens (graduation committee); Delft University of Technology (degree granting institution)","2023","Rural electrification remains a significant challenge for engineers, given its intricate relationship with multiple issues, including geographical constraints and underdeveloped infrastructural provisions. As a result, with the development of Solar Home Systems (SHS) and direct current (DC) microgrids, DC systems for energy access have emerged as a promising solution.
In this context, a bidirectional DC/DC converter serves as a bridge connecting the SHS and the grid. Thus, it is important to design a converter's control mechanism to ensure a smooth and efficient exchange of power in both directions. Beyond this aspect, the system perspective involves the coordination of photovoltaic (PV), battery storage, and grid power supply priorities within the SHS. Consequently, this thesis centers its attention on two objectives: the control of the bidirectional DC/DC converter and the system-level control of the DC microgrid.
To ensure high efficiency under variable loads and smooth transitions between two directional operations, this thesis proposes and evaluates a novel control methodology. Transfer functions are derived through mathematical modeling and PI parameters are determined by analyzing Bode-Plots. This work also shows the simulation and testing results. Both results demonstrate that the proposed control method achieves a high efficiency under light load conditions, maintaining a stable output voltage despite load power dramatic fluctuations.
Analysis of energy exchange between the DC microgrid and SHS involves a bipolar DC microgrid model based on an established grid in Matlab/Simulink. Employing droop control, which is a widely used decentralized strategy, for each converter within the grid. To ensure priority order of power supply in the system, a system-level decentralized control methodology is developed, assuming internal communication within the SHS. Through simulation, the priority order of PV, battery, and grid is verified, along with the impact of dynamic shifts between scenarios on the load. However, given the absence of communication devices in the existing SHS, an alternate decentralized coordinated control strategy is developed and simulated, without direct communication interfaces. Simulation results demonstrate that the SHS bus voltage remains stable even with power supply changes.","Rural Electrification; Bipolar DC Microgrid; Dual Active Half bridge (DAHB); ZVS; Decentralized Control; Burst Mode Operation; Droop Control; PI Control","en","master thesis","","","","","","","","2023-08-23","","","","Electrical Engineering | Electrical Power Engineering","","52.000999996,4.370165186"
"uuid:4c9d2b92-712e-45c3-b410-b7571c9b5852","http://resolver.tudelft.nl/uuid:4c9d2b92-712e-45c3-b410-b7571c9b5852","H-schools as the centre of the neighbourhood in the post-war Netherlands","Zhou, Longyi (TU Delft Architecture and the Built Environment)","Broekhuizen, A. (mentor); Delft University of Technology (degree granting institution)","2023","Through both the lens of sustainability and current events, particularly the pandemic, there is an increasing awareness of the importance of adaptability and intensive use of buildings. In the Netherlands, one form of adaptability and intensive use emerged in the second half of the 20th century in school buildings. One of the main ideas is that schools should have not only supported various educational functions, but also social functions within their neighbourhoods. These new ideas manifested themselves in the H-schools in Amsterdam-West. Existing literature provides theoretical contexts regarding the H-schools. Through further evidence-based study, this thesis examines in what ways the H-schools in Amsterdam achieve their role as community centres. The findings of this research can be valuable for current day designs and plannings.","AR2A011; Post-war school building; Standardisation; Post-war Neighborhood; Community Centre; Reconstruction; Education architecture; H-schools","en","student report","","","","","","","","","","","","Architecture, Urbanism and Building Sciences","AR2A011",""
"uuid:7a0a095b-00e5-4609-abc9-3d412cdc6c52","http://resolver.tudelft.nl/uuid:7a0a095b-00e5-4609-abc9-3d412cdc6c52","Possibilities for treating produced water with ceramic membranes","Zhou, Hanxiao (TU Delft Civil Engineering & Geosciences)","Heijman, Sebastiaan (mentor); Qin, G. (graduation committee); Delft University of Technology (degree granting institution)","2023","Constant flux MF/UF filtration is preferred in real-world applications because it
provides more consistent permeate flow rates than fixed transmembrane pressure studies. Particularly, little is understood about the fouling of ceramic membranes in constant flux filtration modes by nano-sized O/W emulsions. In this study, the effects of emulsion chemistry containing pH, different surfactants, as well as salinity on the alumina and SiC deposited ceramic UF membranes with various physicochemical surface properties in the constant flux mode were compared.
During the research phase, literature research and many interviews have been conducted to discover the food manufacturing context in detail: the drivers and barriers for food manufacturers in developing sustainable products, a review of the current ideation activities of food manufacturers, an analysis of the possible sustainability measures that they can take to create more sustainable products, and an exploration of the trends and developments within the industry (see chapter 2 for elaboration). With the found insights, four opportunity areas are discovered (see chapter 3), and one is chosen to form a design brief (see chapter 4).
Following the guidelines from the design brief, several brainstorming sessions were conducted during the design phase, and the sustainable food product ideation guide was prototyped (see chapter 5). The guide encourages users to think creatively and frequently about sustainability throughout the entire food product development ideation phase. The guide provides value by stimulating creativity, serving as a sustainability exercise, and enabling product development teams to take concrete steps towards the creation of sustainable food products. See chapter 6 for elaboration on the ideation guide.
Then, the ideation guide was evaluated in one pilot session and three review sessions with designers, Accenture consultants and Accenture experts (see chapter 7). Whereafter, the potential use cases of the ideation guide was discussed with various experts from Accenture in chapter 8.
Finally, this report concludes with an implementation plan for the ideation guide, which is designed to encourage food manufacturers to develop more sustainable product ideas, instilling a sustainable mindset that impacts everything they do. The guide offers significant value for Accenture and its food manufacturing clients. For Accenture, the guide offers the opportunity to attract new clients and initiate early-stage conversations about sustainability projects, as well as provide a standardised workshop format with a modular toolkit that saves time and is scalable. Eventually, the digital version of the guide could be developed into Accenture’s own ideation platform for security and IP purposes. The guide provides a low threshold for food manufacturers to experience sustainable food product ideation sessions. It offers tailored workshops, new food product ideas, and concrete next research steps for the development team. Additionally, the digital version of the guide caters to remote employees and assists in integrating sustainability into their practices, helping to initiate company culture change.
The commercialization of electric cars was one of the first steps. Next the transportation industry will look to expand into electric aircraft too. The electric distribution propulsion system is one of the most important areas regarding the feasibility of electric aircraft. This thesis presents a design for an allelectric distribution propulsion system for the year 2038. More specifically, the power converters and safety considerations of the electric architecture will be compared and discussed in this thesis. Existing research was compared to derive optimal solutions for the aircraft requirements. Finally, the conclusion summarises the most important results obtained during the research process for this aircraft application.","Electric aircraft; Power converters; Safety","en","bachelor thesis","","","","","","","","","","","","Electrical Engineering","",""
"uuid:4885cd26-755d-4693-8543-58c70c70bd40","http://resolver.tudelft.nl/uuid:4885cd26-755d-4693-8543-58c70c70bd40","Modeling of router structure for SNN-applicable NoC definitions","Zhou, Yongkang (TU Delft Electrical Engineering, Mathematics and Computer Science)","van Leuken, T.G.R.M. (mentor); Zjajo, Amir (graduation committee); Delft University of Technology (degree granting institution)","2022","Spiking neural networks (SNN), as the third-generation artificial neural network, has a similar potential pulse triggering mechanism to the biological neuron. This mechanism enables the spiking neural network to increase computing power compared to the traditional artificial neural network to process complex information. However, a large number of interconnection resources is required. This requirement is highly consistent with the characteristics of the network on chip (NoC). This thesis is aimed at developing a scalable cycle-accurate simulator based on Noxim, which provides a configurable NoC that can simulate neuron-to-neuron communication for delivering spiking traffic. This simulator achieves several configurable metrics including topology and routing schemes, network size, the number of channels, and neuron mapping methods. This thesis then evaluates the effects of these metrics on performance for two kinds of traffic patterns. To take power consumption and area into account, this thesis also provides an approximate estimate of area and power consumption for trade-offs in the early-design stage.","Spiking Neural Networks(SNNs)); Network-on-chip(NoC); Router design","en","master thesis","","","","","","","","2024-04-20","","","","Electrical Engineering | Circuits and Systems","",""
"uuid:ed3ce146-fb7b-4ab1-83de-48164e38a853","http://resolver.tudelft.nl/uuid:ed3ce146-fb7b-4ab1-83de-48164e38a853","Evaluation of an Ammonia Fueled Combine-cycle Gas Turbine Power System on Maritime Usage","Zhou, Zheng (TU Delft Mechanical, Maritime and Materials Engineering)","van Biert, L. (mentor); Visser, K. (graduation committee); Klein, S.A. (graduation committee); Delft University of Technology (degree granting institution)","2021","Ammonia fuel has been widely considered as an attractive solution for reducing the green house gas emissions over recent years. Adapting ammonia as fuel on ships would highly reduce the carbon footprint of international shipping and off-shore transportation. Among the different systems currently under development for carbon-free power production in the near future, the combined-cycle gas turbine system stands out for its relatively high system efficiency and a potential for running on pure ammonia fuel while maintaining a low level of NOx emission. This thesis project puts a sight on a special design of this type of COGAS power system and tries to adapt it for maritime usage onboard future ships. Previous researches have pointed out the key design features of the ammonia COGAS power system being running under a high fuel-air ratio with a cooling method based on EGR technology and cracking the additional ammonia fuel into hydrogen in the gas turbine system, then this created hydrogen concentration could be used for re-heating the exhaust before it is used by the combined steam cycle. However, current understanding of this type of COGAS system is still limited under static analysis and designed working points. This thesis project tries to provide a basic view on the off-design performance and dynamic behaviors of this COGAS system, and examines if this system is still able to maintain a low level NOx emission under such working conditions. This thesis project combines a dynamic model of an ammonia gas turbine and a chemical thermodynamic model for simulating the chemical behavior of the work fluid inside the gas turbine system. It is found that the fuel-air equivalence ratio of the gas turbine needs to be designed at a high value to ensure the flammability of the hydrogen consisting exhaust in the re-heating process. A very low NOx emission is observed in the gas turbine exhaust under an assumption of complete chemical reactions. The final NOx emission of the COGAS system is found to be within the EEDI Tier III limitation under both rated and part-load working conditions. The thermal efficiency of the gas turbine is relatively low due to the high equivalence ratio, while a system efficiency comparable with current oil-fueled COGAS power system is able to be expected for the full system of ammonia COGAS. On the phase of dynamic analysis, this project has concluded that traditional fuel control method for controlling gas turbine power generation is not adaptable to gas turbine systems working at fuel-rich conditions. A non-linear behavior is observed due to this high equivalence ratio. This thesis provides a new controlling method with controlling both the fuel injection ratio and the EGR ratio with an additional feedback controlling system attached to the original feed-forward system of the fuel control. Basic tests shows that such method is able to generate a dynamic output with the correct tendency. This thesis project also observes a high sensitivity of NOx emission with the presence of additional oxygen in the exhaust under a complete chemical reaction. In this thesis project it is found that the considered ammonia COGAS system maintains the advantage of traditional COGAS power systems and a is able to take an advantage in comparing with medium-speed diesel systems under an ammonia economy. Power output of the ammonia gas turbine is able to be controlled with a combination of fuel control and EGR control. A low NOx emission within the limit of EEDI Tier III is observed under both rated and part-loading conditions of the power system, but this is achieved with the assumption of a complete chemical reaction. Whether this assumption is adaptable to maritime scaled ammonia gas turbine system requires further kinetic analysis on the combustion process and further research efforts in the designing of the combustor system.","Thesis; Ammonia; Gas turbine; Simulation","en","master thesis","","","","","","","","","","","","Marine Technology","",""
"uuid:9d1fbac7-aac7-467d-b91a-05df9592f0ba","http://resolver.tudelft.nl/uuid:9d1fbac7-aac7-467d-b91a-05df9592f0ba","An Improved Design of IPL Hair Removal Device for Generation Z","Zhou, Zhou (TU Delft Industrial Design Engineering)","Jellema, A.H. (mentor); Hao, C. (graduation committee); Buse, Janneke (graduation committee); Delft University of Technology (degree granting institution)","2021","This master thesis reports the research and design activities about designing a new Philips intense pulsed light (IPL) Lumea Prestige hair removal device for generation Z users. Philips invented an Intense pulsed light hair removal device for a painless hair removal experience. However, the new consumers generation Z are coming to the market who are born between 1997 to 2012. Philips would like to see how the IPL device can fit into generation Z consumers. Firstly, research was conducted about the current usability issues of the IPL hair removal device. Secondly, generation Z was selected as the target group because of the current market trend. Thus, user research was conducted about understanding the generation Z personal care characteristics. Contextmapping method was used here for deeper understanding of the users. Next, research was done about finding out how to match the current IPL device insights with the characteristics of the generation Z, and how the Philips IPL device can fit into the generation Z personal care routine. In the end, a design goal was discovered based on the research. Afterwards, co-creation and ideation were conducted for discovering ideas for the design. Moreover, an exploration on shapes was conducted as well. In the end, a new shape and a new design were created for the generation Z users. In the end, usability tests have been conducted with real generation Z participants in order to validate the design goal.","contextmapping; Ergonomics; Interaction; Design; Product design","en","master thesis","","","","","","","","2023-01-26","","","","Design for Interaction","",""
"uuid:60ff93a9-7d8f-4871-a320-98ad661d6945","http://resolver.tudelft.nl/uuid:60ff93a9-7d8f-4871-a320-98ad661d6945","Reliability analysis of sea-dikes in Shanghai city, China","Zhou, Ruoxi (TU Delft Civil Engineering and Geosciences)","Lanzafame, R.C. (mentor); Aguilar Lopez, J.P. (graduation committee); Kuiper, C. (graduation committee); Ke, Q. (graduation committee); Delft University of Technology (degree granting institution)","2020","This research focuses on the estimation the failure probability of Shanghai sea-dikes system, taking into account several failure mechanisms. This method follows fully probabilistic approach, in which all relevant parameters for the resistances and the hydraulic loads vary according to specific distributions.","sea dike; failure probability; Shanghai","en","master thesis","","","","","","","","","","","","Civil Engineering | Hydraulic Engineering","",""
"uuid:cbedd436-39e7-40c1-a1c9-e3c56b503d87","http://resolver.tudelft.nl/uuid:cbedd436-39e7-40c1-a1c9-e3c56b503d87","Library and Sports Center along the wall","Zhou, R. (TU Delft Architecture and the Built Environment; TU Delft Architecture)","Schreurs, E.P.N. (mentor); van Meerbeek, E. (mentor); Lafeber, J.W. (mentor); Bier, H.H. (graduation committee); Delft University of Technology (degree granting institution)","2020","The project focus on a continuous old wall, which separates the site into two, as the “Spolia”. According to the research on both previous and present urban pattern of the neighborhood, the value of the wall is reflected: it is one of the few remnants of the buried river and a defining character in the sites social manifestation. As a result of interactions with the differing segments of wall, it was renovated again and again and the qualities are variant. The wall acts as connection and separation, nature and built environment, protection and orientation, closure and openness. The intention of the master plan is to create a community oriented block, with the wall connect the newly added public facilities and form a linear landscape run through the whole block, thereby inverting the space along the wall from “back” to accessible “front” to serve the residents living in the neighborhood. The architectural program in the master plan is a public building that consists of a library and a sports center. The meaning of a street corner is also taken into consideration due to the site location. The corner building, works as an entrance of the linear “wall” space. Following the alley along the wall from a street corner, a vivid “front”, represents both a spiritual core of history and cohesion of the neighborhood.","wall; urban pattern; reverse; industrial remnants; street corner","en","master thesis","","","","","","","","","","","","Architecture, Urbanism and Building Sciences","",""
"uuid:a040d23f-9eb2-4766-9cb4-4683e65f4bf2","http://resolver.tudelft.nl/uuid:a040d23f-9eb2-4766-9cb4-4683e65f4bf2","A Festive AMC: A Transformation Program for the Academic Medical Center in Amsterdam","Zhou, Kedi (TU Delft Architecture and the Built Environment)","Snijders, Anne (mentor); Bilow, Marcel (mentor); van Bennekom, Henri (graduation committee); Delft University of Technology (degree granting institution)","2020","The project is based on the proposed transformation program for the AMC. The redesign happens in the public squares of the monolith, including a multi-skylight environment design and the reorganization of the public space by a simple intervention of a wooden surface structure.","AMC; skylight; wooden structure","en","master thesis","","","","","","","","","","","","Architecture, Urbanism and Building Sciences","",""
"uuid:a86f06e9-7010-4fcb-b9d0-3e841da66d1b","http://resolver.tudelft.nl/uuid:a86f06e9-7010-4fcb-b9d0-3e841da66d1b","SIS Epidemics on Network with Non-Markovian Curing Process","Zhou, Xiaoyu (TU Delft Electrical Engineering, Mathematics and Computer Science)","Van Mieghem, P.F.A. (mentor); Ma, L. (mentor); Liu, Q. (mentor); Delft University of Technology (degree granting institution)","2019","Susceptible-Infected-Susceptible (SIS) model is commonly used to describe the spreading of virus on networks. However, a real-life epidemic process is not necessarily Markovian. The spreading of diseases, behaviors and information in real systems are sometimes dependent on the characteristics and current status of individuals. Thus it is far from enough to just consider Markovian processes. We need to consider a more general model with non-Markovian processes. Although some recent works focus on the SIS model with a non-Markovian infection process, systematic research on the non-Markovian curing process is still lacking. Therefore, this thesis project is to study the influence of the non-Markovian curing process on the performance of SIS viral spreading on networks. Through continuous-time SIS epidemics simulator, we find some dramatic effects of a non-exponential curing time (while still assuming an exponential infection time) on the prevalence and critical point of effective infection rate by considering Weibullean curing times with same mean, but different shape parameter α. For α ∈ [0.2, 10], the epidemic threshold satisfies τc = 1/λ1, which is the same as the NIMFA conclusions of Markovian SIS process. Relatively, when α is too small, a large number of curing events synchronously happened at the beginning of the simulation, which will lead to collective deaths on finite network. The effect on initial condition of nodes further cause a decline on prevalence and an slow phase transition between healthy state and the meta-stable state. Furthermore, the heavy-tailed distribution of curing time leads to a small percent of nodes still surviving at the meta-stable state, even under a very low effective infection rate. The heavy-tailed distribution gives some nodes an extreme long curing time and thus can infect other nodes with a pretty small probability, thereby maintaining the virus' long-term spread in a small group of nodes. This spreading mode seems can explain some virus spreading phenomenon, like the spreading mode of hepatitis B virus (HBV). Additionally, when the shape parameter α of Weibull distribution is pretty large, the distribution of curing time is like a pulse or a Dirac delta function ( δ function), thus a huge amount of nodes can get synchronously recovered. We find when we control the successful curing probability p =1-1/e ≈0.632, the prevalence of pulse curing at the meta-stable state is equivalent to a Poisson curing process. Therefore, the pulse curing strategy can suppress the spreading of viruses and further save medical resources.","SIS Epidemics; Non-Markovian Curing Process; Epidemic Threshold; Pulse Curing Strategy","en","master thesis","","","","","","","","","","","","Electrical Engineering | Telecommunications and Sensing Systems","",""
"uuid:ecb3796f-ff68-400f-bf2d-a1ad3b340154","http://resolver.tudelft.nl/uuid:ecb3796f-ff68-400f-bf2d-a1ad3b340154","Analysis of current Dutch traffic management effectiveness with automated vehicles: a ramp-metering case study: Simulation Study","Zhou, Moyu (TU Delft Civil Engineering and Geosciences)","van Lint, Hans (graduation committee); Calvert, Simeon (mentor); Taale, Henk (mentor); Schakel, Wouter (mentor); Pan, Wei (graduation committee); Delft University of Technology (degree granting institution)","2019","Automated vehicles are conventional vehicles equipped with advanced sensors, controller and actuators. They achieve intelligent information exchange with the environment through the onboard sensing and cooperative system. vehicles are possible to have situation awareness and automatically analyze the safety and dangerous state of journeys. Finally vehicles can reach destinations following drivers' willing. The ongoing research on intelligent vehicles is mainly about improving the safety, comfort, efficiency and provide an excellent human-car interface. As a self-organizing system, the traffic system is quite complicated. There are many disturbance factors to lead to various traffic problems. One of the daily occurring problems is congestion on the motorway. In order to reduce congestion, Rijkswaterstaat applies various dynamic traffic management (DTM) measures to guide the traffic. It works well nowadays in conventional traffic. However, automated vehicles entered the market recently and will start to play an essential role in future traffic. The automated vehicles' reaction to DTM measures may be different from conventional vehicles while the traffic problems still exist. Therefore, it is necessary to research the effectiveness of current Dutch traffic management in automated vehicles. This thesis aims to investigate the effectiveness of current Dutch DTM measures with driver assistant and partially automated vehicles. Due to the time limitation, only the ramp metering measure will be researched through a simulation study. Therefore the main research question is 'How partial automated driving influences the performance of current Dutch dynamic traffic management system and how can this be evaluated via simulation?'. Three methods are applied, including literature review, simulation and statistical analysis. The literature part reviews levels of automation, various longitudinal and lateral vehicle motion models, which are chosen and modified in the simulation. Many ramp metering algorithms are also introduced in the literature review. The ramp metering controller in the simulation follows RWS algorithm. Besides, the motorway demand and the penetration rate of level 1 and 2 vehicles are two input of the simulation.
From the simulation results, it is concluded that the level 2 automation consisting of Adaptive Cruise Control (ACC) and Lane Change Assistance (LCA) system brings a negative impact on the motorway capacity. The ramp metering measure remains efficient if the penetration rate of level 2 vehicles is low. However, when the capacity reduces to the critical flow set up in the ramp metering controller, Ramp metering loses its efficiency. The parameters in the ramp metering controller therefore, require an update. For further research, it is recommended to simulate the same scenarios with different ramp metering algorithms. Since the functions of the algorithms are different, there might be other robust control algorithms for automated vehicles. Besides, another limitation of this thesis is that the automation system in level 2 vehicles is defined as Adaptive Cruise Control (ACC) plus Lane Change Assistance (LCA) system. Other partial automation systems may have a different effect on the performance of ramp metering. This thesis can be expanded by research the ramp metering performance under various types of partial automation systems.","Dynamic Traffic Management; Ramp Metering","en","master thesis","","","","","","","","","","","","Civil Engineering | Transport and Planning","",""
"uuid:6f1bd2ca-93cf-47dd-862c-0300682df7e9","http://resolver.tudelft.nl/uuid:6f1bd2ca-93cf-47dd-862c-0300682df7e9","Cascade anaerobic digestion system treating waste activated sludge under short sludge retention time: process performance and role of recirculation","Zhou, Tingting (TU Delft Civil Engineering and Geosciences)","de Kreuk, M.K. (mentor); van Lier, J.B. (graduation committee); Hagedoorn, P.L. (graduation committee); Guo, H. (graduation committee); Delft University of Technology (degree granting institution)","2019","Hydrolysis, where the complex insoluble organic matter is hydrolyzed by hydrolytic enzymes, is regarded as rate-limiting step for anaerobic digestion of waste activated sludge (WAS). The cascade system, which consisted of small-reactors in series, was developed in this study to enhance the hydrolysis rate. Degradation efficiency of sludge was strongly related to the sludge retention time (SRT) and recirculation ratio (RR). Therefore, this study investigated the effect of SRT and RR on process performance and hydrolysis enzymatic activity of WAS treatment in the cascade system and conventional single continuous stirred tank reactor (CSTR) system. The cascade system’s chemical oxygen demand (COD), volatile solid (VS), protein and carbohydrates reduction, and methane production could be maintained despite the decrease of SRT, which was associated with an increase in organic loading rate (OLR) (15 d = 3.33 gCOD/L/d, 12 d = 4.16 gCOD/L/d). The performance of reference CSTR system deteriorated at shorter SRT. Hydrolysis, acidogenesis and methanogenesis analysis indicated that shorter SRT accelerated the hydrolysis rate of cascade system from 1.29±0.23 gCOD/L/d (SRT=15 d) to 1.59±0.19 gCOD/L/d (SRT=12 d), leading to the increase of overall degradation of WAS. The enhancement of hydrolysis rate was supported by the increased protease and cellulase activity detected at shorter SRT. Recirculating the effluent from reactor3 (R3) to reactor 1 (R1) was also essential to maintain the performance. The results not only showed deteriorating performance of cascade system regarding lower COD, VS, protein, carbohydrates reduction and methane production, but also presented lower hydrolysis enzymatic activity at 2% RR compared to 10% RR. 10% recirculation of solid phase, which contained biomass and sludge-attached enzymes, was beneficial to recover the performance of cascade system but the performance was not as good as that with 10% recirculation of both solid and liquid phase of R3 effluent. The cations analysis revealed that the required quantities of Cobalt (Co), Nickel (Ni) and Zinc (Zn) was highest in R1 while the concentration of soluble Co, Ni and Zn was lowest in R1. The concentration of Co, Zn and Ni was increased along AD of cascade system, providing the opportunities of offering increment of trace elements to the growth of microbial community and enzymes formation in R1. In conclusion, cascade system had better performance at shorter SRT compared to single CSTR. The recirculation played an important role to maintain the superior performance of cascade system under high OLR.","cascade system; waste activated sludge; hydrolysis; sludge retention time; recirculation ratio; hydrolysis enzymatic activity; trace elements","en","master thesis","","","","","","The confidential period of this master thesis is 2 years.","","2021-10-31","","","","","",""
"uuid:c7c9c170-eb70-4cf2-adfb-1d08bc1b74d7","http://resolver.tudelft.nl/uuid:c7c9c170-eb70-4cf2-adfb-1d08bc1b74d7","Automated classification of satellite data of informal urban settlements","Zhou, Zequn (TU Delft Electrical Engineering, Mathematics and Computer Science)","Yorke-Smith, Neil (mentor); Rózsás, Árpád (mentor); Delft University of Technology (degree granting institution)","2019","Urban areas are rapidly expanding in developing countries. One of goals of the United Nations Human Settlement Programme (UN-Habitat) is to understand and guide urban development for some developing regions.
Currently, the approaches that UN-Habitat is using cost plenty of workforce, material, and time. Therefore, UN-Habitat is interested in exploring new approaches on how to drive down costs and time, which would not only allow for faster responses but expanding their analysis. Since UN-Habit is already using satellite imagery for urban mapping, our research question is formulated as: Can we develop an automated system that provides valuable information about urban development for the UN-Habitat from satellite image data (e.g. building detection)?
After examining the satellite imagery provided by UN-Habitat and those available publicly (crowd AI and Inria Areial datasets), we define the main task as a building segmentation task. In this research, we study deep learning techniques for building segmentation on satellite image data.
Duo to the fact that the number of images and the quality available for the region of interest (Middle East) for UN-Habitat are insufficient to solely rely on for training. Therefore, we use some public datasets (crowd AI and Inria Areial datasets) for training and evaluation, whose regions and construction practice are different.
Starting with testing several classic segmentation algorithms (FCN8S, SegNet, Deep\_Lab and U-Net), from the experiment results, we find that the performance can still be improved. Then, we propose two novel data reweighing methods, named border weight and inter-building distance weight, to improve the detection performance. By increasing the weights of the pixels outside but close to the border of the buildings, the model is encouraged to learn those information and thus performs better. Inspired by the idea of reweighing the non-building pixels, we investigate whether modifying building pixels can achieve further improvement. We propose a new label representation -- multi-level boundary label that does help to improve the segmentation results. Based on the distance to the building boundary, we can divide building pixels into multiple classes, as their pixel values can be affected by some factors such as trees and shadows. From the experiment result, we can see that the performance is improved since the model captures more information about the buildings. Next, we propose a new neural network architecture that utilizes the two pixel weights, and the multi-level boundary label explained above. Our proposed model achieves state-of-the-art building segmentation performance compared with several classic segmentation methods.
For example, the proposed model's mean intersection of union on the test dataset is 3\% higher than that of FCN8S.
Our model also uses fewer number of parameters (~16 million in total) because we only use the first 13 layers of the VGG16 as the encoder and we do not use any convolutional layers in the decoder part.
The results using the publicly available datasets show that with enough good quality input the building segmentation is possible, hence should be possible in other regions as well.
To see the performance of our proposed model on the UN-Habitat dataset, we train our model with public datasets (crowd AI and Inria Areial datasets) and then use transfer learning to fit the UN-Habitat dataset.
The building detection performance is reduced still good results are obtained. For achieving comparable performance in the region of interest for UN-Habitat more labelled data is needed. Based on the results using the publicly available datasets, we are confident that a comparable performance is attainable.
Regarding the research question, our answer is definitely yes. We not only show that it is possible to obtain information about urban development from satellite image but also propose a new model with great performance in our work.","deep learning; Semantic segmentation; Satellite Imagery; buildng detection","en","master thesis","","","","","","","","","","","","Computer Science | Data Science and Technology","",""
"uuid:ffdcf947-06df-4941-a587-bdf008f87783","http://resolver.tudelft.nl/uuid:ffdcf947-06df-4941-a587-bdf008f87783","Interwoven: Designing Biodigital Objects with Plant Roots: Exploring Material Structure and Experience","Zhou, Jiwei (TU Delft Industrial Design Engineering)","Karana, Elvin (mentor); Wu, Jun (mentor); Delft University of Technology (degree granting institution)","2019","Interwoven is a textile grown from plant roots, showing the intelligence of plants. It is originally from the attempt of training plant roots to form a manmade pattern since 2015 by visual artist Diana Scherer based in Amsterdam. Due to fragility, it still remains an artistic work. However, Interwoven has a great potential for sustainable product design if further development is made through altering the material structure.
Collaborating with Materials Experience Lab of Industrial Design Engineering in TU Delft, Diana Scherer wants to bring an artistic material closer to people’s daily life. The author, by following the Material Driven Design method (Karana et al., 2015)*, develop the material by altering material structure through hacking the growing process, incorporating generative design techniques and the results from the user studies, with a particular emphasis on people’s experience on interpretive level. Digital Fabrication techniques are used to design the structural pattern for achieving functionally graded material properties (e.g. spatially graded stiffness), and shape optimisation.
Based on Diana Scherer’s experience and early experiments, a few techniques are synthesized and developed in the tinkering with Interwoven. Some potential structures for digital biofabrication are: [1] root growth can be manipulated to mirror digitally generated patterns, which would provide intended technical and experiential characteristics in Interwoven; [2] roots grown in agar gel change properties to stiffer and stronger by hand feeling (further mechanical tests are needed); [3] roots can sew through descrete obstacles in their growing direction and these obstacles can be designed with digital fabrication techniques.
Combining the insights and experiential studies, a material concept has been created: showing roots glue-ability to porous materials and growing traces to blend nature and man-made world. The material experience vision is to exhibit the glue-ability of Interwoven through a daily object co-created by roots and digital manufactured structures and bring forward the collision and collaboration between natural growth and man-made world. The final product concept is to imitate one of the most mass-produced daily products - IKEA ALSEDA, questioning the current way of manufacturing and material use. The co-creation structure increased durability of Interwoven.","Material Driven Design; Biomaterials; Digital Biofabrication; Growing Material","en","master thesis","","","","","","","","","","","","Design for Interaction","Interwoven",""
"uuid:da06f359-3720-4c4a-b10d-d510a49450e7","http://resolver.tudelft.nl/uuid:da06f359-3720-4c4a-b10d-d510a49450e7","Investigation into the DC-DC Converter for the PV Integrated Bidirectional EV Charging System","Zhou, Mengxi (TU Delft Electrical Engineering, Mathematics and Computer Science)","Bauer, P. (mentor); Qin, Z. (mentor); Rueda, José L. (graduation committee); Delft University of Technology (degree granting institution)","2019","With the rapid development of the economy and the continuous innovation of technology, the automobile industry is developing at a high speed. While providing convenient transportation and improving the efficiency of production and living, it has also caused a series of problems such as the energy shortage and environmental pollution. Electric vehicles (EVs) are getting more and more attention and support because of their unique advantages such as the energy saving and zero emission. Once the electric vehicle can charge from the clean and sustainable energy source such as the solar and wind energy, it can be an environment-friendly mode of transportation. Therefore, the photovoltaic (PV)
integrated EV charging system appears in recent years. In the meanwhile, ABB is also interested in finding a way to combine their PV products and the EV chargers to make a more compact and efficient PV integrated EV charging system.
A possible solution of making a more compact PV integrated EV charging system is to use the multiport converter which can integrate the separated DC-DC converters. However, the traditional multiport converter needs a large number of active switches and the control of the whole converter is complex. Moreover, the zero voltage switching (ZVS) operation cannot be achieved easily in the traditional multiport converter. Therefore, a dual boost integrated dual active bridge (DAB) converter used for the PV integrated bidirectional EV charging system is investigated in this master thesis project.
This master thesis is the first step to investigate the dual boost integrated DAB converter working with a large output voltage range, which can be compatible with the new CHAdeMO standard (CHAdeMO 2.0) regarding the charging voltage range and make the whole PV integrated EV charging system more compact and efficient. The investigation is divided into three parts which are: the working principle and control analysis, the power loss modeling and analysis and the experimental verification tests.
First of all, the specifications of the converter are clarified, the circuit structure, the working principle of the two interleaved boost converters in the primary side and the working principle of the whole converter are analyzed. Secondly, the parameters of the converter are calculated according to the specifications and all the equations in terms of the voltage, the current and the output power are
deduced. The power modes and the control structure of the converter are also introduced. Afterwards, the soft switching characteristics of the switches and the circulating power in the dual boost integrated DAB converter are investigated by considering the DC bus voltage, PV voltage, and the EV battery voltage, and then the ZVS region is enlarged by applying the DC blocking capacitor voltage control. Besides, the transistor candidates are chosen and the power loss model and the thermal model of the candidates are built. The loss breakdown, the loss ratio and the thermal performance of the switches are analyzed and evaluated.
An analysis tool which can analyze the voltage and current at different points, the output power, the soft switching region and the circulating power of the dual boost integrated DAB converter is developed in Mathcad. This analysis tool is not only suitable for this project but also can be used to do other customized designs, which helps to decrease the time and cost for the development. The simulation model including the control loop and the thermal model of this converter is built in PLECS to check the feasibility of the design. Finally, a test bench is built and the experimental tests are implemented to verify the analysis and the simulation results.","Multiport DC-DC converter; EV charging system; SSPS plus PWM modulation","en","master thesis","","","","","","","","2021-08-31","","","","Electrical Engineering","",""
"uuid:575ef61e-0d65-48cd-9b2b-285505c26148","http://resolver.tudelft.nl/uuid:575ef61e-0d65-48cd-9b2b-285505c26148","Virtual Fitting of Personalized Knitwear","Zhou, Wenjun (TU Delft Industrial Design Engineering)","Jellema, A.H. (mentor); Ruiter, I.A. (graduation committee); Delft University of Technology (degree granting institution)","2019","The aim of this project was to build a pleasant customer experience of personalizing, virtual fitting and ordering made-to-measure knitwear, so as to improve their satisfaction on fit as well as reduce waste in the fashion industry.
The project started with a deep dive into the design context. Relevant knowledge from academic and industry was learned, together with the technology learning on 3D virtual fitting.The research findings revealed several problems on customers’ side: the lack of sensory inputs (visual and tactile) for evaluating apparel fit in online environment; the perceived complexity and uncertainty of making choices on personalized garments; the gap between one's fit requirements (depending on body sizes and personal fit preference) and actual garment sizes. The research findings also confirmed the perceived usefulness of 3D virtual fitting as a promising solution for online shopping. By using the software CLO3D, the visualization of knitwear is achievable, as well as the simulation of how the knitwear fits to different human body models. After the analysis stage, the focus of the project was transferred to how to connect the research findings to the design. An explicit and specific design statement was established, “To design a website that enables customers to customize and order knitwear made to their measurements, in all possible looks, sizes and fits. Include the use of 3D virtual fitting in the website to boost customer confidence in evaluating clothing fit online and shopping enjoyment. In the end deliver the real garment that achieves customer satisfaction”. The design goal, along with a website framework and a list of design requirements, gave a clear guide where the design should go. During the design stage, several iteration cycles were conducted to evaluate the design effectiveness of each part of the website, so as to quickly make design decisions and refine the concept in an early design phase. The final concept was built based on both the design requirements and new inputs from design process. In the last stage an evaluation study was carried out. A user test was done with thirteen participants using the website prototype to finish an order, and a comparison between physical try-on and virtual fitting was done with two of them. From the study results it could be evidenced that the website is able to support people to finish the online process of customizing made-to-measure knitwear, and for the majority the function of virtual fitting achieves its intended effects of enhancing customer confidence and shopping enjoyment. In the end, a review of the concept showed the validity and limitations of this project, some recommendations were discussed as well.","virtual fitting; fashion industry; interaction design; personalization","en","master thesis","","","","","","","","","","","","Design for Interaction","",""
"uuid:8ac49de5-b436-4209-b699-5b0f542ef755","http://resolver.tudelft.nl/uuid:8ac49de5-b436-4209-b699-5b0f542ef755","Novel Doping Free Metal-oxide Carrier Selective Passivating Contacts for Solar Cells","Zhou, YiLong (TU Delft Electrical Engineering, Mathematics and Computer Science)","Isabella, Olindo (mentor); Yang, Guangtao (graduation committee); Delft University of Technology (degree granting institution)","2019","Carrier selective passivating contact (CSC) is considered to be a promising direction for surface passivation research because it performs passivation for both non-contacted and contacted areas. Conventional heavy doping CSCs are subject to a few drawbacks such as significant Auger recombination, parasitic absorption, complicated processing and relatively high fabrication cost. An alternative approach is by using transition metal oxides (TMO) where nm-thick metal oxides are introduced with easy and cost effective processes to realize the asymmetric conductivity for charge carriers. In this project, we investigated the passivation property and carrier selectivity of two types of TMOs, namely MoOx as hole transport layer (HTL) and TiOx as electron transport layer (ETL).
The performance of MoOx based HTL is characterized at device level. By optimizing the metallization process, interfacial (i)a-Si:H layer thickness, textured surface pre-treatment and annealing conditions, an ultimate PCE of 17.60% is achieved, with Voc being 655 mV, Jsc being 38.36 mA/cm2 and FF being 70.40%.
The passivation quality of TiOx based ETL is characterized both by symmetric test for the passivation properties and at device level. First, the passivation property of single TiOx layer and NAOS-SiO2/TiOx stacks are investigated. With the optimization of layer thickness and FGA conditions, a Voc of ~680 mV is obtained in both cases. After which, we investigated the passivation degradation caused by changing a new TiO2 source material. We conclude that the passivation degradation is mainly attributed to the non-uniform TiOx coating resulted from the reduced free mean path of evaporated TiOx due to TiO2 outgassing during deposition. Meanwhile, we also studied the influence of different interfacial layer between c-Si and TiOx such as (i)a-Si:H thin layer where a Voc of ~660mV is achieved by using new TiO2 source. Eventually, all optimized ETL structures are tested in FBC solar cells with p+ poly-SiOx at the front side as HTL. The results demonstrate that all cells are showing similar passivation quality (Voc=~575 mV) and the champion cell of 14.21% efficiency is achieved in c- Si/TiOx stack, with Jsc being 30.53 mA/cm2 and FF being 74.97%.
When it comes to the existing design codes, the shear design methods of reinforced concrete slabs loaded in uniaxial in-plane force are developed from the tests of beams rather than slabs, which may lead to the underestimation of the design resistance. Through experiments of seven slabs, a related study of the validity of existing shear design methods has been performed by Bui et al. (2017). However, there is no existing literature about the application of nonlinear finite element analysis towards the reinforcement concrete slabs mentioned above so far. In this thesis, one single nonlinear finite element analysis is applied to seven slabs of experiment to study the validation of nonlinear finite element analysis on the RC slabs without shear reinforcement loaded in concentrated out-of-plane load and uniaxial in-plane loads. The validation is studied by comparing results from finite element analysis, experiment and finite element analysis from Nana et al. (2017), which mainly includes shear load – displacement curve, development of crack pattern, failure modes and the influence of uniaxial load on the structural behaviour. In addition, the shear capacity under uniaxial in-plane load is studied by comparing results from analytical assessment based on existing codes, experiment and nonlinear finite element analysis.
When compared with experiment, nonlinear finite element analysis shows a close shear capacity of all seven slabs but stiffer structural behaviour. The development of cracks is similar to the observation of experiment. The failure modes indicated by nonlinear finite element analysis is more likely punching shear rather than one-way shear that is demonstrated in the experiment. The influence of increasing uniaxial compression on shear capacity is larger than what is observed in experiment while increasing tension has smaller influence. By comparing the prediction of shear capacity from experiment, existing codes and nonlinear finite element analysis, it can be concluded that NLFEA is unconservative in prediction of shear capacity of the RC slabs without shear reinforcement loaded in concentrated out-of-plane loads and uniaxial in-plane loads. Some suggestions are given for further study. Improvement of modelling is suggested. For instance, finer mesh could lead to more accurate results, and insights of bond-slip reinforcement could generate more precise results. Furthermore, the study of safety formats is suggested in further study to consider the uncertainty due to random variation of material properties. In addition, more experiments and nonlinear finite element analysis are suggested to get insights of the influence of uniaxial loads on structural behaviour of RC slabs without shear reinforcement.
Currently, diverse approaches and techniques are being used and refined to reach the ultimate goal; the cost estimation is to accurately forecast the final cost of a project with no design details available. Generally, estimators’ experience plays a critical role here, and the availability of historical cost data is also crucial. The process is significantly dependent on an export-driven approach. However, decisions made by experts can be subjective and error-prone especially when the relationships between cost drivers and the target cost are not fully understood or even identified. Consequently, cost estimation to a fair level of accuracy is hardly possible to achieve manually within a restricted time. In recent years, civil engineering domain has begun to consider machine learning technique as an optimal approach in tackling the predictive problem through a data-driven approach. Adaptive Network-based Fuzzy Inference System (ANFIS) (a hybrid model of Artificial Neural Network and Fuzzy Inference System) is advantageous in managing uncertainties and representing knowledge. This research aims at investigating the applicability of using the ANFIS for cost estimation during the conceptual phase.","Machine Learning; Neural Networks; Fuzzy Inference System; Cost Estimation; Brick Pavement; ANFIS","en","master thesis","","","","","","","","","","","","Civil Engineering | Construction Management and Engineering","",""
"uuid:2c11834e-f6f4-41aa-93e0-0298dc07cf25","http://resolver.tudelft.nl/uuid:2c11834e-f6f4-41aa-93e0-0298dc07cf25","Numerical Simulation for the Pressure Distribution of the Compaction Roller in in-situ consolidation processes","Zhou, Peixuan (TU Delft Aerospace Engineering)","Shroff, S. (mentor); Teuwen, Julie J.E. (graduation committee); Çelik, O. (graduation committee); Delft University of Technology (degree granting institution)","2018","Automated tape or fiber placement (ATP/AFP) with in-situ consolidation has been identified as a promising manufacturing technique for thermoplastic (TP) composites, which are highly in-demand in the aerospace industry for future aircraft structural applications. This manufacturing technique is attractive since it has the potential to eliminate the energy and time consuming autoclave consolidation. However, low quality is one of the biggest challenges in the application of in-situ consolidation. It seems that pressure contribution to the bond quality has received less attention than thermal one. Therefore, this work is initiated to simulate the pressure distribution between the compaction roller and the mandrel.
The objective in this work is to predict the pressure distribution in the contact area between the rubber-covered roller and the mandrel in room temperature by finite element methods (FEM). Rubber material is characterized by mechanical testing and then modeled as hyperelastic material. 3rdd-order Ogden material model is found to well describe the strain- stress behavior of rubber material. The material constants are then implemented in FE models as an input. The pressure distribution is predicted by FE modes and the influence of compaction force, rubber thickness, pre-stretching force on the pressure distribution are discussed, followed by an optimization between compaction force and rubber thickness. Experiments are conducted to validate the FE models regarding the three influencing factors, that are: (a). compaction force, (b). with/without pre-stretching and (c). various rubber thickness. Rubber deformation can be captured by the digital image correlation (DIC) Pressure distribution is obtained from the Prescale pressure measurement film produced by Fujifilm®, which are the films that show different color densities under different pressures. Experimental results of strain and pressure distribution are compared with FEM results, followed by discussions and conclusions.
It can be concluded that pre-stretching force should be used to avoid rubber-roller separation and prevent rubber from moving out to the sides. Both of the compaction force and rubber thickness affects the maximum pressure and contact length linearly. A trade- off between compaction force and rubber thickness can be made based on the force limit of the equipment and pressure requirements.","Thermoplastic Composite; in-situ consolidation; compaction roller; Finite Element Analysis; Experimental validation; Silicone rubber","en","master thesis","","","","","","","","","","","","Aerospace Engineering","",""
"uuid:60253231-f6e8-47c3-a1c6-1e6dde4e06aa","http://resolver.tudelft.nl/uuid:60253231-f6e8-47c3-a1c6-1e6dde4e06aa","Effects of Redox-mediator Electrolyte on the Electrochemical Performance of a Nonaqueous Li-O2 battery","Zhou, Zhimin (TU Delft Electrical Engineering, Mathematics and Computer Science)","Wagemaker, Marnix (mentor); Li, Zhaolong (mentor); Kelder, Erik (graduation committee); van Eijck, Lambert (graduation committee); Delft University of Technology (degree granting institution)","2018","","","en","master thesis","","","","","","","","2019-05-25","","","","","",""
"uuid:96966266-d7ce-41bf-9521-c7a7a5046e35","http://resolver.tudelft.nl/uuid:96966266-d7ce-41bf-9521-c7a7a5046e35","Food Island: Creating a Resilient Food System for the AMA","Leung, Ranee (TU Delft Architecture and the Built Environment; TU Delft Urbanism); Zhou, Yixiao (TU Delft Architecture and the Built Environment; TU Delft Urbanism); Rodríguez Salcedo, Cristian (TU Delft Architecture and the Built Environment; TU Delft Urbanism); von Meijenfeldt, Charlotte (TU Delft Architecture and the Built Environment; TU Delft Urbanism); van Marrewijk, Franka (TU Delft Architecture and the Built Environment; TU Delft Urbanism)","Balz, Verena Elisabeth (mentor); Dabrowski, M.M. (mentor); Delft University of Technology (degree granting institution)","2018","Governments and private and non-profit organisations from international to local levels have acknowledged the idea that more sustainable systems are required to reduce our ecological footprint (WWF, 2016, Jonkhoff, 2012). The food system is a very important aspect within our lives, socially as well as economically but it is also one of the most important causes of unsustainability. The Amsterdam Metropolitan Area (AMA), a key player within the global food sector, is also working to a more sustainable system with their focus on a circular economy. This research outlines the fact that in order to reach a more sustainable economy, there should also be an emphasis on resilience. In analyzing the region, there were several dependencies highlighted within the food system. Within the aspects of production, retail and end of life, each are dependent on a handful of controlling and dominating stakeholders as well as unsustainable and uncircular practices. Thus, there is a heavy emphasis on the food system needing to adapt and change to growing demands and trends.
This led to our research question of, How can the food system become more resilient in the AMA to promote a sustainable circular economy? In our research, scenario planning and weather mapping were used to showcase and locate feasible opportunities for our goals and strategies within the AMA. The primary strategies to create resiliency within the food system were to decentralize, diversify and connect aspects related to various urban and agri-food trends. This project envisions a decentralized system that contains a dense network of diverse and independent stakeholders with localized sustainable projects. There is also an emphasis on creating smaller and shorter connections within the chain.This includes incorporating and empowering various smaller stakeholders and actors with positive incentives but also restricting dominating stakeholders with policies and regulations. In addition, through the creation of more transparency through integrated and multiscaled design solutions, this will increase awareness and promote healthy and sustainable practices within the system. Food island encourages a thriving circular economy that is resilient and thus more sustainable.