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Geographical flows: a fresh perspective on quantifying urban function

Urban Informatics 2024年第1期3卷 1-9页

作者： Pei, Tao Yan, Xiaorui Shu, Hua Wang, Xi Chen, Xiao Guo, Sihui Jiang, Jingyu Song, Ci Chen, Jie State Key Laboratory of Resources and Environmental Information System Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China University of Chinese Academy of Sciences Beijing China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing China School of Computer Science and Information Engineering Hubei University Wuhan China Beijing Institute of Surveying and Mapping Beijing China Nanjing Institute of Surveying Mapping & Geotechnical Investigation Co. Ltd Nanjing China

Urban function refers to various roles and activities that take place in an urban region or a public facility. Previous research only focused on the types of urban function and its quantitative characterization did not attract enough attention. In this paper, we highlight the issue of quantifying the urban function and divide it into two aspects: one is the intensity of the urban function, which can be seen as the capacity to accommodate people engaging in activities related to the function, and the other is its influence on the surrounding area. Due to the cause-and-effect dynamics between urban functions and geographical flows, which refer to the human or objects moving between locations, geographical flows have been used to estimate the intensity and influence of urban function. Based on the review of recent updates, this paper provides a research framework for utilizing flow data to quantify urban function in terms of intensity and influence. Regarding the intensity, the indices are mainly based on the volume of inflow/outflow and their ratio. Regarding the influence, there are two types of indices for evaluating it: one for planar facilities and the other for linear facilities. To describe the intensity and influence of the urban function simultaneously, the volume along with the length of flows are considered into the indices, which can quantify the importance or irreplaceability of a place or facility. The analysis shows that the geographical flows provide a new perspective for quantifying urban function in terms of intensity and influence.

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Phyllotaxis-inspired nanosieves with multiplexed orbital angular momentum

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eLight 2021年第1期1卷 46-56页

作者： Zhongwei Jin David Janoschka Junhong Deng Lin Ge Pascal Dreher Bettina Frank Guangwei Hu Jincheng Ni Yuanjie Yang Jing Li Changyuan Yu Dangyuan Lei Guixin Li Shumin Xiao Shengtao Mei Harald Giessen Frank Meyer zu Heringdorf Cheng-Wei Qiu Department of Electrical and Computer Engineering National University of Singapore4 Engineering Drive 3Singapore 117583Singapore College of Optical and Electronic Technology China Jiliang UniversityHangzhou 310018China Faculty of Physics and Center for Nanointegration Duisburg-Essen(CENIDE) University of Duisburg-EssenLotharstrasse 1-2147057 DuisburgGermany Department of Materials Science and Engineering Shenzhen Institute for Quantum Science and EngineeringSouthern University of Science and TechnologyShenzhen 518055China Beijing Qianjunyide Technology Co.Ltd Beijing 100031China. Physics Institute and Stuttgart Center of Photonics Engineering(SCoPE) University of Stuttgart70569 Stutt-gartGermany. School of Physics University of ElectronicScience and Technology of ChinaChengdu 611731China. Key Laboratory of Optoelectronic Materials Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China. Department of Electronic and Information Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SARChina. Department of Materials Science and Engineering City University of Hong Kong83 Tat Chee AvenueKowloonHong Kong SARChina. State Key Laboratory On Tunable Laser Technology Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information SystemShenzhen Graduate SchoolHarbin Institute of TechnologyShenzhen 518055China.

Nanophotonic platforms such as metasurfaces,achieving arbitrary phase profiles within ultrathin thickness,emerge as miniaturized,ultracompact and kaleidoscopic optical vortex ***,it is often required to segment or interleave independent sub-array metasurfaces to multiplex optical vortices in a single nano-device,which in turn affects the device’s compactness and channel ***,inspired by phyllotaxis patterns in pine cones and sunflowers,we theoretically prove and experimentally report that multiple optical vortices can be produced in a single compact phyllotaxis nanosieve,both in free space and on a chip,where one meta-atom may contribute to many vortices *** time-resolved dynamics of on-chip interference wavefronts between multiple plasmonic vortices was revealed by ultrafast time-resolved photoemission electron *** nature-inspired optical vortex generator would facilitate various vortex-related optical applications,including structured wavefront shaping,free-space and plasmonic vortices,and high-capacity information metaphotonics.

关键词： Phyllotaxis vortex nanosieve Free-space Plasmonic vortices Ultrafast time-resolved

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Curing Stress Effect on Stability, Microstructure, Matric Suction and Electrical Conductivity of Cementitious Tailings Backfills

SSRN

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SSRN 2022年

作者： Chen, Shunman Yilmaz, Erol Wang, Wei Wang, Yi-Ming School of Civil Engineering and Architecture East China Jiaotong University Jiangxi Nanchang330013 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Hebei Province Shijiazhuang050043 China Jiangxi Key Laboratory of Disaster Prevention-mitigation and Emergency Management East China Jiaotong University Jiangxi Nanchang330013 China Department of Civil Engineering Geotechnical Division Recep Tayyip Erdogan University Fener RizeTR53100 Turkey School of Civil and Resources Engineering University of Science and Technology Beijing Beijing100083 China

Cementitious tailings backfill (CTB) is a regularly used technique for most mines at home and aboard since it has a significant meaning for the recycling of total tailings and enhances the safety of underground mines. Thus, studying the behavior of the CTB materials exposed to diverse curing stresses is fairly vital to guarantee the whole stability and long-term ageing of underground mining structures. This paper inspects the effect of diverse curing stresses (0 kPa – witness, 180 kPa, 360 kPa and 540 kPa) on physico-mechanical characteristics of CTB materials subjected to a curing age of up to 28 days. Based on lab tests, uniaxial compression and microstructure analyses are performed for all the specimens. To well characterize the self-desiccation behavior of CTB specimens, suction and electrical conductivity are also scrutinized during their curing processes. Results indicate that curing of CTBs under stress ranging from 0 to 540 kPa can improve their strength gains to some extent. Irrespective of curing stress, CTB’s suction is enlarged while its porosity is dropped once increased with curing age and stress, respectively. There exists a robust power function between suction and strength while there is a linear link between electrical conductivity and strength. One can state from this study that curing stress must be significantly taken into account during the backfill mixture proportions’ design. © 2022, The Authors. All rights reserved.

关键词： Pore structure

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Large-Scale Spatiotemporal Deep Learning Predicting Residential Indoor Pm2.5 Concentration Using a Bayesian Neural Network Model

SSRN

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SSRN 2023年

作者： Dai, Hui Liu, Yumeng Wang, Jianghao Ren, Jun Gao, Yao Dong, Zhaomin Zhao, Bin Department of Building Science School of Architecture Tsinghua University Beijing100084 China Beijing Key Laboratory of Indoor Air Quality Evaluation and Control Tsinghua University Beijing100084 China School of Space and Environment Beihang University Beijing100191 China State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China Sustainable Urbanization Lab Department of Urban Studies and Planning Massachusetts Institute of Technology CambridgeMA02139 United States Shenzhen Institute of Building Research Co. Ltd China

Indoor PM2.5 pollution is one of the leading causes of death and disease worldwide. As monitoring indoor PM2.5 concentrations on a large scale is challenging, it is urgent to assess population-level exposure and related health risks to develop an easy-to-use and generalized model to predict indoor PM2.5 concentrations and spatiotemporal variations at the global level. Existing machine learning models of indoor PM2.5 are prone to deliver single-point predictions, and their input strategies are not widely applicable. Here, we developed a Bayesian neural network (BNN) model for predicting the distribution of indoor daily average PM2.5 concentration based on multiple data sources available from nationwide comprehensive sensor-monitoring records in China. The BNN model showed good performance with a 10-fold cross-validation R2 of 0.70, mean-absolute-error of 9.45 μg/m3, root-mean-square error of 13.3 μg/m3, and 95% prediction interval coverage of 85%. Our modeled population-weighted annual indoor PM2.5 concentration for China in 2019 was 22.8 μg/m3, far exceeding the WHO standard. This model can be applied to predict indoor PM2.5 concentrations on a large spatiotemporal scale, making it valuable for assessing and managing indoor air pollution-related health risks. © 2023, The Authors. All rights reserved.

关键词： Health risks

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QoS-aware User Association and Transmission Scheduling for Millimeter-Wave Train-ground Communications

arXiv

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arXiv 2023年

作者： Zhang, Xiangfei Niu, Yong Yang, Tao Xiao, Xian Ding, Jianwen Chen, Sheng Zhong, Zhangdui Wang, Ning Ai, Bo State Key Laboratory of Rail Traffic Control and Safety China Frontiers Science Center for Smart High-speed Railway System Beijing Jiaotong University Beijing100044 China State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing100044 China National Mobile Communications Research Laboratory Southeast University Nanjing211189 China School of Electronics and Computer Science University of Southampton SouthamptonSO17 1BJ United Kingdom Beijing Engineering Research Center of High-speed Railway Broadband Mobile Communications Beijing Jiaotong University Beijing100044 China School of Information Engineering Zhengzhou University Zhengzhou450001 China

With the development of wireless communication, people have put forward higher requirements for train-ground communications in the high-speed railway (HSR) scenarios. With the help of mobile relays (MRs) installed on the roof of the train, the application of Millimeter-Wave (mm-wave) communication which has rich spectrum resources to the train-ground communication system can realize high data rate, so as to meet users’ increasing demand for broad-band multimedia access. Also, full-duplex (FD) technology can theoretically double the spectral efficiency. In this paper, we formulate the user association and transmission scheduling problem in the mm-wave train-ground communication system with MR operating in the FD mode as a nonlinear programming problem. In order to maximize the system throughput and the number of users meeting quality of service (QoS) requirements, we propose an algorithm based on coalition game to solve the challenging NP-hard problem, and also prove the convergence and Nash-stable structure of the proposed algorithm. Extensive simulation results demonstrate that the proposed coalition game based algorithm can effectively improve the system throughput and meet the QoS requirements of as many users as possible, so that the communication system has a certain QoS awareness. Copyright © 2023, The Authors. All rights reserved.

关键词： Game theory

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Analysis of the Influence of Green Building Fresh Air system on Indoor Environment Based on Improved Analytic Hierarchy Process

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IOP Conference Series: Earth and Environmental Science 2020年第3期546卷

作者： Liu Hua Chen Xiaoyi Niu Runping Su Yuhai State Key Laboratory of Air-conditioning Equipment and System Energy Conservation Guangdong Key Laboratory of Refrigeration Equipment and Energy Conservation Technology Zhuhai Guangdong 519070 China. Beijing University of Civil Engineering and Architecture Beijing 100044 China

With the increasing pollution of outdoor environment, it is urgent for people to improve indoor air quality and create a good living and working environment. Using fresh air system to regulate indoor air quality is one of the commonly used technologies in green building design. The fresh air system energy consumption accounts for about 30% of the total energy consumption of air conditioning system, which has an important impact on the overall evaluation of green buildings. Based on the improved Analytic hierarchy process (AHP), an objective and accurate evaluation of the indoor environment of the fresh air system is carried out by questionnaire. The main purpose of this article is to find out the main factors that the fresh air system affects the indoor environment in the green building, while reducing the energy consumption of the fresh air system and creating a good indoor environment.

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Low-noise 750-MHz spaced Yb:fiber frequency combs

arXiv

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arXiv 2018年

作者： MA, YUXUAN XU, BO ISHII, HIROTAKA MENG, FEI NAKAJIMA, YOSHIAKI MATSUSHIMA, ISAO SCHIBLI, THOMAS R. ZHANG, ZHIGANG MINOSHIMA, KAORU 1-5-1 Chofugaoka Chofu Tokyo182-8585 Japan State Key Laboratory of Advanced Optical Communication System and Networks School of Electronics Engineering and Computer Science Peking University Beijing100871 China Project 1-5-1 Chofugaoka Chofu Tokyo182-8585 Japan Department of Physics University of Colorado at Boulder 2000 Colorado Avenue BoulderCO80309-0390 United States

Growing interest of frequency combs is stimulating the development of high repetition rate combs. However, increasing the repetition rate to ∼GHz levels while maintaining tight phase locking to an optical reference w... 详细信息

关键词： Fibers

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A Modular Framework for Task-Agnostic, Energy Shaping Control of Lower-Limb Exoskeletons

TechRxiv

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TechRxiv 2024年

作者： Lin, Jianping Thomas, Gray Cortright Divekar, Nikhil V. Peddinti, Vamsi Gregg, Robert D. State Key Laboratory of Mechanical System and Vibration School of Mechanical Engineering Shanghai Jiao Tong University Shanghai200240 China Department of Mechanical Engineering Texas A&M University College StationTX77843 United States Department of Robotics University of Michigan Ann ArborMI48109 United States Department of Electrical and Computer Engineering University of Michigan Ann ArborMI48109 United States

Various backdrivable lower-limb exoskeletons have demonstrated the electromechanical capability to assist volitional motions of able-bodied users and people with mild to moderate gait disorders, but there does not exist a control framework that can be deployed on any joint(s) to assist any activity of daily life in a provably stable manner. This paper presents the modular, multi-task optimal energy shaping (M-TOES) framework, which uses a convex, data-driven optimization to train an analytical control model to instantaneously estimate assistive joint torques across activities for any lower-limb exoskeleton joint configuration. The presented modular energy basis is sufficiently descriptive to fit normative human joint torques (given normative feedback from signals available to a given joint configuration) across sit-stand transitions, stair ascent/descent, ramp ascent/descent, and level walking at different speeds. We evaluated controllers for four joint configurations (unilateral/bilateral, hip/knee) of the modular M-BLUE exoskeleton on eight able-bodied users navigating a multi-activity course comprising the primary activities of daily life. The two unilateral conditions significantly lowered overall muscle activation across all tasks and subjects (p © 2024, CC BY-NC-SA.

关键词： Exoskeleton (Robotics)

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Study on Deep Reinforcement Learning for Multi-Task Scheduling in Cloud Manufacturing

SSRN

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SSRN 2022年

作者： Xiao, Jiuhong Cai, Yishuai Wang, Wanru Chen, Yong College of Economic and Social Development Nankai University Tianjin300072 China Institute for Quantum Information State Key Laboratory of High Performance Computing College of Computer Science and Technology National University of Defense Technology Changsha410073 China School of Information Management and Artificial Intelligence Zhejiang University of Finance and Economics Hangzhou310018 China College of Civil Engineering and Architecture Zhejiang University Hangzhou310058 China

Cloud manufacturing is an emerging manufacturing paradigm, which enables the simultaneous processing of multiple manufacturing tasks submitted by customers through centralized management and planning of manufacturing services offered by distributed enterprises. To date, various meta-heuristics algorithms such as ant colony optimization algorithm, and genetic algorithm have been widely employed to solve the cloud manufacturing multi-task scheduling (CMMS) problem to improve the efficiency of multi-task scheduling. However, these algorithms need sophisticated design procedures and laborious parameter tuning, making their adaptation to dynamic, large-scale manufacturing environments difficult. Deep reinforcement learning (DRL), because of its efficiency and flexibility, has recently attracted increasing attention from researchers and has shown promising performance in solving combinatorial optimization problems. Nevertheless, little is known about the performance of DRL technologies in solving the CMMS problem. Therefore, in this study, three state-of-the-art DRL technologies, including proximal policy optimization (PPO), deep deterministic policy gradient, and normalized advantage function, are selected to systematically investigate the potential of DRL in solving the CMMS problem. A comprehensive comparison of these DRL technologies is conducted in terms of effectiveness and efficiency, robustness and adaptability, and scalability. Experimental results indicate that PPO is superior to other technologies in solving the CMMS problem. © 2022, The Authors. All rights reserved.

关键词： Reinforcement learning

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Conducted EMI simulation for a high power Ultra-precision PMSM driven by PWM converter

Conducted EMI simulation for a high power Ultra-precision PM...

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IEEE International Symposium on Electromagnetic Compatibility (EMC)

作者： Youpeng Huangfu Shuhong Wang Juanning Yang Hongxu Wang Luca Di Rienzo Djilali Hamza State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong University Xi'an China Dipartimento di Elettronica Informazione e Bioingegneria Politecnico di Milano Milan Italy Qinchuan Technology Research Institute Software & System Institute Qinchuan Machine Tool & Tool Group Corp. Baoji China Electrical and Computer Engineering Dept. Queen's University Kingston Ontario Canada

ISBN: (纸本)9781509014439

The conducted electromagnetic interference (EMI) and overvoltage characteristics for a spindle permanent magnet synchronous motor (PMSM) driven by pulse width modulation (PWM) converter are comprehensively presented. The high power, ultra-precision PMSM is applied to a computer numerical control (CNC) grinding machine. The conducted EMI prediction model mainly includes multi-core shielded cable, high frequency (HF) converter and PMSM models. The multi-transmission line (MTL) theory is employed to establish the multi-core shielded cable considering their coupling effect caused by the control pairs. The parasitic capacitance for the PWM converter is calculated by using the analytical formula. The HF equivalent circuit model of the PMSM is obtained combining the methods of impedance measurement and vector fitting method. The influence of the rotor position on the PMSM impedance measurement is considered. The common mode (CM) and differential mode (DM) interference voltage and current both for the output of inverter and the input of PMSM terminals are conducted by using the prediction model. The parametric influence of the long multi-core shielded cables on the overvoltage for the PMSM terminal is discussed.

关键词： Decision support systems

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