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Journal of Systems Science & Complexity 2024年第1期37卷 136-151页

作者： PAN Zini CHEN Ben M Department of Mechanical and Automation Engineering The Chinese University of Hong KongHong KongChina

In this paper,the authors study the cooperative target-fencing problem for n-dimensional systems and a target with a general trajectory.Without using the velocity of the vehicles,a position feedback control law is proposed to fence the general target into the convex hull formed by the vehicles.Specifically,the dynamics of each vehicle is described by a double-integrator system.Two potential functions are designed to guarantee connectivity preservation of the communication network and collision avoidance among the vehicles.The proposed approach can deal with a target whose trajectory is any twice continuously differentiable function of time.The effectiveness of the result is verified by a numerical example.

关键词： Multi-agent systems networked systems target fencing

Efficient and Stable Inverted Perovskite Solar Modules Enabled by Solid-Liquid Two-Step Film Formation

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Nano-Micro Letters 2024年第9期16卷 571-582页

作者： Juan Zhang Xiaofei Ji Xiaoting Wang Liujiang Zhang Leyu Bi Zhenhuang Su Xingyu Gao Wenjun Zhang Lei Shi Guoqing Guan Abuliti Abudula Xiaogang Hao Liyou Yang Qiang Fu Alex K.‑Y.Jen Linfeng Lu Graduate School of Science and Technology Hirosaki University3‑BunkyochoHirosaki 036‑8561Japan Department of Materials Science and Engineering Department of ChemistryHong Kong Institute for Clean EnergyCity University of Hong Kong KowloonHong Kong 999077People’s Republic of China The Interdisciplinary research Center Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201210People’s Republic of China Shanghai Synchrotron Radiation Facility(SSRF) Zhangjiang LabShanghai Advanced Research InstituteChinese Academy of SciencesShanghai201204People’s Republic of China JINNENG Clean Energy Technology Ltd. Jinzhong 030300ShanxiPeople’s Republic of China Hangzhou Zhongneng Photoelectricity Technology Co. Ltd.Hangzhou 310018People’s Republic of China College of Chemical Engineering and Technology Taiyuan University of TechnologyTaiyuan 030024People’s Republic of China Institute of Regional Innovation Hirosaki University3‑BunkyochoHirosaki 036‑8561Japan

A considerable efficiency gap exists between large-area perovskite solar modules and small-area perovskite solar cells.The control of forming uniform and large-area film and perovskite crystallization is still the main obstacle restricting the efficiency of PSMs.In this work,we adopted a solid-liquid two-step film formation technique,which involved the evaporation of a lead iodide film and blade coating of an organic ammonium halide solution to prepare perovskite films.This method possesses the advantages of integrating vapor deposition and solution methods,which could apply to substrates with different roughness and avoid using toxic solvents to achieve a more uniform,large-area perovskite film.Furthermore,modification of the NiO_(x)/perovskite buried interface and introduction of Urea additives were utilized to reduce interface recombination and regulate perovskite crystallization.As a result,a large-area perovskite film possessing larger grains,fewer pinholes,and reduced defects could be achieved.The inverted PSM with an active area of 61.56 cm^(2)(10×10 cm^(2)substrate)achieved a champion power conversion efficiency of 20.56%and significantly improved stability.This method suggests an innovative approach to resolving the uniformity issue associated with large-area film fabrication.

关键词： Inverted perovskite solar cells Perovskite solar modules Two-step film formation Crystallization Defect passivation

Relationship Between Individuals’Epidemic Risk Perception Within Living Space and Subjective Well-Being:Empirical Evidence from China after the First Wave of COVID-19

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Chinese Geographical Science 2024年第2期34卷 369-382页

作者： SONG Jiangyu ZHOU Suhong KWAN Mei-Po ZHENG Zhong School of Geography and Planning Sun Yat-sen UniversityGuangzhou 510006China Guangdong Provincial Engineering research Center for Public Security and Disaster Guangzhou 510275China Institute of Space and Earth Information Science the Chinese University of Hong KongHong Kong 999077China Department of Geography and Resource Management the Chinese University of Hong KongHong Kong 999077China Institute of Future Cities the Chinese University of Hong KongHong Kong 999077China Center for Territorial Spatial Planning and Real Estate Studies Beijing Normal UniversityZhuhai 519000China

It is common to observe the epidemic risk perception(ERP)and a decline in subjective well-being(SWB)in the context of public health events,such as Corona Virus Disease 2019(COVID-19).However,there have been few studies exploring the impact of individuals’ERP within living space on their SWB,especially from a geographical and daily activity perspective after the resumption of work and other activities following a wave of the pandemic.In this paper,we conducted a study with 789 participants in urban China,measuring their ERP within living space and examining its influence on their SWB using path analysis.The results indicated that individuals’ERP within their living space had a significant negative effect on their SWB.The density of certain types of facilities within their living space,such as bus stops,subway stations,restaurants,fast food shops,convenience shops,hospitals,and public toilets,had a significantly negative impact on their SWB,mediated by their ERP within living space.Additionally,participation in out-of-home work and other activities not only increased individuals’ERP within living space,but also strengthened its negative effect on their SWB.

关键词： subjective well-being epidemic risk perception living space the density of facilities out-of-home activities

Double stabilizations and convergence analysis of a second-order linear numerical scheme for the nonlocal Cahn-Hilliard equation

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Science China Mathematics 2024年第1期67卷 187-210页

作者： Xiao Li Zhonghua Qiao Cheng Wang Department of Applied Mathematics The Hong Kong Polytechnic UniversityHong KongChina Department of Mathematics The University of MassachusettsNorth DartmouthMA 02747USA

In this paper,we study a second-order accurate and linear numerical scheme for the nonlocal CahnHilliard equation.The scheme is established by combining a modified Crank-Nicolson approximation and the Adams-Bashforth extrapolation for the temporal discretization,and by applying the Fourier spectral collocation to the spatial discretization.In addition,two stabilization terms in different forms are added for the sake of the numerical stability.We conduct a complete convergence analysis by using the higher-order consistency estimate for the numerical scheme,combined with the rough error estimate and the refined estimate.By regarding the numerical solution as a small perturbation of the exact solution,we are able to justify the discrete?^(∞)bound of the numerical solution,as a result of the rough error estimate.Subsequently,the refined error estimate is derived to obtain the optimal rate of convergence,following the established?∞bound of the numerical solution.Moreover,the energy stability is also rigorously proved with respect to a modified energy.The proposed scheme can be viewed as the generalization of the second-order scheme presented in an earlier work,and the energy stability estimate has greatly improved the corresponding result therein.

关键词： nonlocal Cahn-Hilliard equation second-order stabilized scheme higher-order consistency analysis rough and refined error estimate

Interplay of laser power and pore characteristics in selective laser melting of ZK60 magnesium alloys:A study based on in-situ monitoring and image analysis

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Journal of Magnesium and Alloys 2024年第4期12卷 1346-1366页

作者： Weijie Xie Hau-Chung Man Chi-Wai Chan Department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHong KongChina School of Mechanical and Aerospace Engineering Queen’s UniversityBelfast BT95AHUK research Institute for Advanced Manufacturing The Hong Kong Polytechnic UniversityHong KongChina

This study offers significant insights into the multi-physics phenomena of the SLM process and the subsequent porosity characteristics of ZK60 Magnesium(Mg)alloys.High-speed in-situ monitoring was employed to visualise process signals in real-time,elucidating the dynamics of melt pools and vapour plumes under varying laser power conditions specifically between 40 W and 60 W.Detailed morphological analysis was performed using Scanning-Electron Microscopy(SEM),demonstrating a critical correlation between laser power and pore formation.Lower laser power led to increased pore coverage,whereas a denser structure was observed at higher laser power.This laser power influence on porosity was further confirmed via Optical Microscopy(OM)conducted on both top and cross-sectional surfaces of the samples.An increase in laser power resulted in a decrease in pore coverage and pore size,potentially leading to a denser printed part of Mg alloy.X-ray Computed Tomography(XCT)augmented these findings by providing a 3D volumetric representation of the sample internal structure,revealing an inverse relationship between laser power and overall pore volume.Lower laser power appeared to favour the formation of interconnected pores,while a reduction in interconnected pores and an increase in isolated pores were observed at higher power.The interplay between melt pool size,vapour plume effects,and laser power was found to significantly influence the resulting porosity,indicating a need for effective management of these factors to optimise the SLM process of Mg alloys.

关键词： Selective laser melting(SLM) Magnesium(Mg)alloys Biodegradable implants Porosity In-situ monitoring

Distributed Nash Equilibrium Seeking on Compact Action Sets over Jointly Strongly Connected Switching Networks

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Journal of Systems Science & Complexity 2024年第1期37卷 63-81页

作者： HE Xiongnan HUANG Jie Department of Mechanical and Automation Engineering The Chinese University of Hong KongHong Kong 999077China.

This paper studies the distributed Nash equilibrium seeking(DNES)problem for games whose action sets are compact and whose network graph is switching satisfying the jointly strongly connected condition.To keep the actions of all players in their action sets all the time,one has to resort to the projected gradient-based method.Under the assumption that the unique Nash equilibrium is the unique equilibrium of the pseudogradient system,an algorithm is proposed that is able to exponentially find the Nash equilibrium.Further,the authors also consider the distributed Nash equilibrium seeking problem for games whose actions are governed by high-order integrator dynamics and belong to some compact sets.Two examples are used to illustrate the proposed approach.

关键词： Compact action sets jointly strongly connected switching graphs Nash equilibrium seeking projected gradient-based algorithm.

A fully distributed robust optimal control approach for air-conditioning systems considering uncertainties of communication link in IoT-enabled building automation systems

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Energy and Built Environment

Energy and Built Environment 2024年第3期5卷 446-454页

作者： Wenzhuo Li Rui Tang Shengwei Wang Institute for Environmental Design and Engineering The BartlettUniversity College LondonUK Department of Building Environment and Energy Engineering The Hong Kong Polytechnic UniversityKowloonHong Kong research Institute for Smart Energy The Hong Kong Polytechnic UniversityKowloonHong Kong

Internet of Things(IoT)technologies are increasingly implemented in buildings as the cost-effective smart sens-ing infrastructure of building automation systems(BASs).They are also dispersed computing resources for novel distributed optimal control approaches.However,wireless communication networks are critical to fulfill these tasks with the performance influenced by inherent uncertainties in networks,e.g.,unpredictable occurrence of link failures.Centralized and hierarchical distributed approaches are vulnerable against link failure,while the robustness of fully distributed approaches depends on the algorithms adopted.This study therefore proposes a fully distributed robust optimal control approach for air-conditioning systems considering uncertainties of com-munication link in IoT-enabled BASs.The distributed algorithm is adopted that agents know their out-neighbors only.Agents directly coordinate with the connected neighbors for global optimization.Tests are conducted to test and validate the proposed approach by comparing with existing approaches,i.e.,the centralized,the hierarchical distributed and the fully distributed approaches.Results show that different approaches are vulnerable against to uncertainties of communication link to different extents.The proposed approach always guarantees the optimal control performance under normal conditions and conditions with link failures,verifying its high robustness.It also has low computation complexity and high optimization efficiency,thus applicable on IoT-enabled BASs.

关键词： Multi-agent system Edge computing Air-conditioning system Internet of Things(IoT) Communication link failure

A computation design method for architectural artifacts adapted from traditional Kagome bamboo basketry techniques

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Frontiers of Architectural research 2024年第2期13卷 249-264页

作者： Hiroyuki Shinohara Tung Hoi Peter Chan School of Architecture The Chinese University of Hong KongHong KongChina

This study is a digital form-finding and manual fabrication experiment in woven architectural design,with one traditional weaving style,Kagome,used to scale the craft up into an architectural-scale bamboo woven artifact.Kagome is a trihexagonal pattern employed in traditional bamboo basketry as a triaxial weaving system,resulting in an object with a self-bracing capacity without the use of fasteners owing to its interlacing lattices.Although existing studies and tools have addressed triaxial weaving design and representation,the current consideration of the advantages of weaving with bamboo is insufficient.To address this research gap,this study develops a computational design method based on studies on bamboo basketry.This allows for the representation and exploration of design geometries using combinations of regular triangular meshes for the fabrication of Kagome woven bamboo artifacts.A full-scale mock-up was fabricated to evaluate the effectiveness of the method.The mock-up demonstrated the self-bracing properties of Kagome,but there were discrepancies between the mock-up and the design.Factors affecting bamboo weaving on an architectural scale have been identified within this study to inform future research on woven bamboo structures.

关键词： Traditionalbamboo craft Triaxialmaterial interlacing Bamboo Computational design methods Mesh block combinationsystem Architecturalwoven artifact

Does astrocytic L-lactate enhance cognition through myelination?

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Neural Regeneration research 2024年第6期19卷 1167-1168页

作者： Mastura Akter Ying Li Department of Neuroscience City University of Hong Kong Department of Biomedical Sciences City Universit of Hong Kong Centre for Regenerative Medicine and Health Hong Kong Institute of Science & Innovation Chinese Academy of Sciences Centre for Biosystems Neuroscience and Nanotechnology City University of Hong Kong

Introduction: Astrocytes, the predominant glial cell in the brain, play a vital role in a plethora of central ner vous system functions. They are the major storage site of glycogen in the central nervous system. They produce L-lactate by glycogenolysis and glycolysis which is then transported to neurons(Magistreti and Allaman,

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A Privacy-preserving Energy Management System Based on Homomorphic Cryptosystem for IoT-enabled Active Distribution Network

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Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 167-178页

作者： Qian Hu Siqi Bu Wencong Su Vladimir Terzija the Department of Physics Hong Kong Baptist UniversityHong KongChina the Department of Electrical and Electronic Engineering Shenzhen Research InstituteThe Hong Kong Polytechnic UniversityHong KongChina the Department of Electrical and Computer Engineering University of Michigan-DearbornDearbornMI 48128USA the School of Engineering Newcastle UniversityNewcastleUK

Active distribution network(ADN),as a typically cyber-physical system,develops with the evolution of Internet of Things(IoTs),which makes the network vulnerable to cybersecurity threats.In this paper,the eavesdropping attacks that lead to privacy breaches are addressed for the IoT-enabled ADN.A privacy-preserving energy management system(EMS)is proposed and empowered by secure data exchange protocols based on the homomorphic cryptosystem.During the information transmission among distributed generators and load customers in the EMS,private information including power usage and electricity bidding price can be effectively protected against eavesdropping attacks.The correctness of the final solutions,e.g.,optimal market clearing price and unified power utilization ratio,can be deterministically guaranteed.The simulation results demonstrate the effectiveness and the computational efficiency of the proposed homomorphically encrypted EMS.

关键词： Eavesdropping attack energy management system homomorphic cryptosystem Internet of Things(IOTs) active distribution network(ADN) privacy-preserving