Multi-objective Optimization of Micro-catchment Rainwater management to Improve the Sponge City Project in China

학위논문(석사)--서울대학교 대학원 :공과대학 건설환경공학부,2019. 8. 한무영 .도시 홍수는 자유로운 도시화의 결과로 많은 중국의 도시에서 심각한 문제입니다. 중국 정부는 2014 년에 문제를 해결하고 지속 가능한 물 관리를 장려하기 위해 Sponge City 프로젝트 (SPC)를 제안했습니다. 그러나 제한된 녹지 및 자금 부족과 같은 SPC의 장벽으로 인해 예비 결과가 불만족 스럽습니다. 빗물 수확 시스템 (RWHS)은 도시 하수관을 줄일 수있는 잠재력을 지니고있어 하수도 시스템에 대한 압력을 덜어줍니다. 또한, 빗물은 물 부족의 해결책으로 대체 수원이 될 수 있습니다. 그러나 RWHS는 중국에서별로 주목을받지 못했으며 제한된 문헌 만 있습니다. 본 연구에서는 수자원 균형 시뮬레이션을 기반으로 한 홍수 완화 성능을 조사하기 위해 강수량 순서 (설계 강우량, 일일 평균 강우량 및 실제 일별 강우량)를 사용했으며, 현재 연구에서 데이터 선택 부족이 정량적으로 논의되고 적절한 입력 데이터 세트는 추가 평가를 위해 선택됩니다. SPC의 홍수 완화 효과는 유효 강수량뿐만 아니라 짧고 강화 된 설계 폭풍을 사용하여 추정되며, 선정 된 31 개 도시에서 적절한 탱크 크기가 정의되고 적용되어 건설 후 효율성이 향상 될 수 있는지 평가됩니다 RHWS. 홍수 완화 및 절수 성능은 모두 전국에 빗물 탱크를 추가함으로써 긍정적으로 영향을받는 것으로 나타났습니다. 그런 다음 SPC와 RWHS의 설계를위한 최적의 솔루션을 찾기위한 최적화 분석에 경제적 요소가 포함되며, 기존 방법은 향후 빗물 설비 건설에 대한 제안을하기위한 좋은 도구가 될 것입니다.Urban flood is a serious problem in many of Chinas cities as a result of unfettered urbanization. The Chinese government proposed Sponge City project (SPC) in 2014 to address the problem as well as promote sustainable water management. However, some barriers of SPC, such as limited green space and fund shortage, make the preliminary results unsatisfactory. Rainwater harvesting system (RWHS) has the potential ability to reduce the urban runoff, relieving the pressure on the municipal sewer system. In addition, rainwater could be an alternative water source as a solution for water scarcity. Yet RWHS has not got much attention in China and there is only limited literature. In this study the different rainfall sequences (design rainfall, average daily rainfall, and real daily rainfall) are used to investigate the performance of flood mitigation based on water balance simulation, besides the shortage of data selection in current research is discussed quantitatively and the appropriate input data sets are chosen for further evaluation. The flooding mitigation and water saving effectiveness of SPC are estimated by using short and intensified design storm, as well as the real daily rainfall respectively, while the proper tank size is defined and applied in selected 31 cities, for evaluating the possibly enhanced efficiency after the construction of RHWS. It is seen that both of flood mitigation and water saving performances are positively affected by adding rainwater tanks all over the country. Then economic factor is included in the optimization analysis to search the optimal solutions for the design of SPC and RWHS, and the established method would be a good tool to give some suggestions for future construction of rainwater facilities.Chapter 1. Introduction 1 1.1. Background ……………………………………………………. 1 1.1.1. Water challenges in China …………………………..… 1 1.1.2. Sponge city project …………………………..………… 2 1.1.3. Motivation ……………………………...………………... 5 1.2. Objectives………………………………………...……………….. 6 References…………………………...…………………………………... 8 Chapter 2. Hydrologic factor 20 2.1. Introduction 12 2.2. Study sites and data compilation ............................................ 13 2.3. Methodology ……………………………………………………. 16 2.3.1. Water balance simulation ……………………………….. 16 2.3.2. Indicators for estimation ………………………………… 18 2.4. Results …………………………………………………………… 19 2.5. Discussion ……………………………………………………….. 23 References ……………………………………………………………… 25 Chapter 3. Improved Method 20 3.1. Introduction ……………………………………………………… 27 3.1.1. Chicago model …………………………………………… 27 3.1.2. SCS CN method …………………………………………. 29 3.2. Study sites and data …………………………………………… 30 3.2.1. Study sites and rainfall data …………………………….. 30 3.2.2. Establishment of calculation ……………………………… 32 3.3. Methodology ………………………………………………...……. 33 3.3.1. Runoff calculation …………………………………………. 33 3.3.2. Indicators of flood mitigation and water saving ……….. 37 3.4. Results …………………………………………………………….. 38 3.4.1. Performance of flood mitigation …………………………. 38 3.4.2. Performance of water saving ………………………..…… 42 References ……………………………………………………………… 46 Chapter 4. Optimization 49 4.1. Introduction ……………………………………………………… 49 4.2. Methodology ……………………………………………………... 50 4.2.1. Economic analysis ………………………………………… 50 4.2.2. Objectives ………………………………………………….. 51 4.2.3. Method …………………………………………………….. 51 4.2.4. Variations …………………………………………………... 54 4.3. Results …………………………………………………………….. 55 4.3.1. Scenario A ……………………..………………………….. 55 4.4.2. Scenario B ………………………………………………… 58 References ……………………………………………………………… 62 Chapter 5. Conclusions 64 Appendix 67 Abstract in Korean 72Maste

Characterization of ionic, dipolar and molecular mobility in polymer systems

Changes in the ionic and dipolar molecular mobility in a polymer system are the basis for the changes in the dielectric mechanical properties of polymer materials. Frequency Dependent Dielectric Measurements (FDEMS) and Ion Time-of-Flight (ITOF) are two important techniques to investigate ionic and dipolar molecular mobility in polymer systems. The results can be related to the macro- and molecular dielectric, electrical and dynamic properties of polymeric materials. The combination of these two methods provides a full view of electric, dielectric and dynamic behavior for the systems as they undergo chemical and/or physical changes during polymerization crystallization, vitrification, and/or phase separation.;The research on microscopic mass mobility in polymer systems was done on three aspects: (1) ion mobility in an epoxy-amine reaction system; (2) dipolar mobility and relaxation during dimethacrylate resin cure and (3) dye molecule migration and diffusion in polymer films.;In the ion mobility study, we separately monitor the changes in the ion mobility and the number of charge carriers during the epoxy-amine polymerization with FDEMS and ITOF measurements. The isolation of the number of carriers and their mobility allows significant improvement in monitoring changes in the state and structure of a material as it cures.;For the dipolar mobility and relaxation study, FDEMS measurements were used to detect structural evolution and spatial heterogeneity formation during the polymerization process of dimethacrylate resins. The dielectric spectra, glass transition (Tg) profiles and dynamic mechanical measurements were used to investigate the existence of two cooperative regions of sufficient size to create two alpha-relaxation processes representing oligomer rich and polymer microgel regions during the polymerization.;For the dye migration research, we tried to develop a visually color changing paper (VCP) due to dye molecule migration in polymer films. The mobility of dye molecules in polyvinyl films was controlled by the acidity of the environment. Ionamine derivatives of dyes were stable when mixed with acid. their diffusion in polymer films can be quickly triggered as the result of an acid/base neutralization reaction. The effect of the type of base, acid and the compatibility of polymer films on the diffusion rate is discussed

An Adaptive Compression and Communication Framework for Wireless Federated Learning

Federated learning (FL) is a distributed privacy-preserving paradigm of machine learning that enables efficient and secure model training through the collaboration of multiple clients. However, imperfect channel estimation and resource constraints of edge devices severely hinder the convergence of typical wireless FL, while the trade-off between communications and computation still lacks in-depth exploration. These factors lead to inefficient communications and hinder the full potential of FL from being unleashed. In this regard, we formulate a joint optimization problem of communications and learning in wireless networks subject to dynamic channel variations. For addressing the formulated problem, we propose an integrated adaptive $n$ -ary compression and resource management framework (ANC) that is capable of adjusting the selection of edge devices and compression schemes, and allocates the optimal resource blocks and transmit power to each participating device, which effectively improves the energy efficiency and scalability of FL in resource-constrained environments. Furthermore, an upper bound on the expected global convergence rate is derived in this paper to quantify the impacts of transmitted data volume and wireless propagation on the convergence of FL. Simulation results demonstrate that the proposed adaptive framework achieves much faster convergence while maintaining considerably low communication overhead

Dipolar-glass-like relaxor ferroelectric behaviour in the 0.5BaTiO3-0.5Bi(Mg1/2Ti1/2)O3 electroceramic

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On building a dynamic security vulnerability detection system using program monitoring technique

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Mode-pairing quantum key distribution with advantage distillation

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Recent reports have shown that global population is rising and more fossil fuels, such as coal and natural gas, are required to meet the global energy demands. The adverse effect of burning fossil fuels has become a concern due to its contribution to global warming and increasing emissions of greenhouse gases, particularly CO2, have been regarded as a main cause for the rising temperature of the earth’s surface. To partially address this pressing social problem, CO2 capture technology, which has been considered as an efficient and feasible technology to reduce global CO2 emissions, has been deeply explored and tested over the last decades. Among several available CO2 capture technologies, the MEA-based post-combustion CO2 capture process is considered a mature technology for mitigating CO2 emissions due to its inherent benefits, e.g. high CO2 capture capacity, low price of MEA solvent and fast kinetics. However, a large amount of energy is required to regenerate MEA solvent. Thus, the efficiency of fossil fuel-fired power plants decreases. In addition, the dynamic operation of the CO2 capture process needs to be explored in more detail to analyze the transient operation of this plant and its interaction with the operation of the fossil fuel-fired power plants. Thus, the development of MEA-based CO2 capture technology has gained attention. Based on above, in the present study, a dynamic model of a pilot-scale MEA-based CO2 capture plant was first developed and a flexibility analysis under critical operating conditions was performed followed by an implementation of simultaneous scheduling and control using the proposed dynamic model. Based on the pilot-scale CO2 capture plant, a natural gas power plant integrated with a commercial-scale MEA-based post-combustion CO2 capture process was developed. The proposed model was used to perform a flexibility analysis on the integrated systems. This study first presents a dynamic flexibility analysis of a pilot-scale post-combustion CO2 capture plant using MPC. The critical operating conditions in the plant’s main load (flue gas flowrate) were initially identified in open-loop and closed-loop. Insights from this analysis have shown that oscillatory changes with high frequencies content in the load are particularly harmful to the system in closed-loop. Taking these insights into account, a simultaneous scheduling and control framework was developed to identify optimal operating policies under the critical operating conditions in the flue gas flowrate. The results obtained from this framework were compared against a sequential scheduling and control approach. The results show that the proposed integrated framework specifies more economically attractive operating policies than those obtained from the sequential approach. Furthermore, a model describing the dynamic operation of a 453 MWe NGCC power plant integrated with a commercial-scale post-combustion CO2 capture plant has been developed. The proposed model has been used to evaluate the dynamic performance of the integrated process under various scenarios, e.g. changes in the reboiler heat duty and power plant inputs. In addition, the transient operation of the integrated plant using a pre-defined (scheduled) trajectory profile in the consumption of steam in the reboiler unit has been compared to the case of constant withdrawal of steam from the power plant. The results show that a coordinated effort between the two plants is needed to run the integrated plant efficiently and at near optimal economic points under changes in power demands. In the present work, flexibility analysis and scheduling and control have been performed based on the proposed pilot-scale CO2 capture process. Furthermore, the dynamic behaviour of the natural gas power plant integrated with the commercial-scale CO2 capture plant was assessed under several scenarios that are likely to occur during operation. The insights gained through these analyses will be instrumental to design basic and advanced control and scheduling strategies for integrated NGCC-CO2 capture plants

Discussion on course design of “Programming and Problem Solving” based on OBE-CDIO

Based on the OBE-CDIO model, this paper discusses how to design the course to achieve the goal of students’ ability training by taking the course “Programming and problem Solving” as an example. On the basis of analyzing the curriculum objectives and students’ needs, the student-centered teaching mode is realized through the research of course content design, teaching method selection and engineering case development. Through the questionnaire survey of the students in the course, some experience about this course is gained, and further research directions are proposed