检索结果-南通市图书馆

Quantization and Event-Triggered Policy design for Encrypted Networked Control

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第4期11卷 946-955页

作者： Yongxia Shi Ehsan Nekouei the department of Electrical engineering City University of Hong KongHong KongChina

This paper proposes a novel event-driven encrypted control framework for linear networked control systems(NCSs),which relies on two modified uniform quantization policies,the Paillier cryptosystem,and an event-triggered strategy.Due to the fact that only integers can work in the Pailler cryptosystem,both the real-valued control gain and system state need to be first quantized before encryption.This is dramatically different from the existing quantized control methods,where only the quantization of a single value,e.g.,the control input or the system state,is considered.To handle this issue,static and dynamic quantization policies are presented,which achieve the desired integer conversions and guarantee asymptotic convergence of the quantized system state to the equilibrium.Then,the quantized system state is encrypted and sent to the controller when the triggering condition,specified by a state-based event-triggered strategy,is satisfied.By doing so,not only the security and confidentiality of data transmitted over the communication network are protected,but also the ciphertext expansion phenomenon can be relieved.Additionally,by tactfully designing the quantization sensitivities and triggering error,the proposed event-driven encrypted control framework ensures the asymptotic stability of the overall closedloop system.Finally,a simulation example of the secure motion control for an inverted pendulum cart system is presented to evaluate the effectiveness of the theoretical results.

关键词： Cyber-security encrypted control event-triggered control(ETC) networked control systems(NCSs) semi-homomorphic encryption

Hierarchical crystalline-amorphous nanocomposites with high strength and large deformability enabled by elemental diffusion

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2024年第4期171卷 150-161页

作者： Liqiang Wang Heyi Wang Xin Zhou Huangliu Fu James Utama Surjadi Shuo Qu Xu Song Rong Fan Yang Lu department of Mechanical engineering City University of Hong KongHong KongChina Nano-Manufacturing Laboratory(NML) Shenzhen Research Institute of City University of Hong KongShenzhen 518057China Chengdu Research Institute City University of Hong KongChengdu 610200China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China department of Mechanical and Automation engineering The Chinese University of Hong KongHong KongChina department of Mechanical engineering The University of Hong KongHong KongChina

Amorphous/nanocrystalline dual-phase structures have recently emerged as an effective way for over-coming the strength-ductility trade-offand breaking the limitation of the reverse Hall-Petch effect.Here,we proposed a new strategy to develop a hierarchical and interconnected amorphous-crystalline nanocomposite arising from the nanoscale elemental interdiffusion and oxygen adsorption behavior dur-ing thermal treatment processes.The nanocomposite consisted of a three-dimensional(3D)hierarchical network structure where the crystalline phase(Cr-Co-Ni-Al)was embedded into the Al-O-based amor-phous phase network with critical feature sizes encompassing three orders of magnitude(from microm-eter to nanometer scale).It can achieve ultrahigh compression yield strength of-3.6 GPa with large homogeneous deformation of over 50%strain.The massive interstitial atoms induced lattice distortion and hierarchical amorphous phase boundary contributed to the strength improvement.in situ Uniaxial compression inside a transmission electron microscope(TEM)revealed that the exceptional deformability of the nanocomposites resulted from the homogenous plastic flow of nano-sized amorphous phase and the plastic co-deformation behavior restricted by the nano-architected dual-phase interface.The proposed dual-phase synthesis approach can outperform conventional nanolaminates design strategies in terms of the mechanical properties achievable while providing a pathway to easily tune the microstructure of these nanolaminates.

关键词： Nanolaminates Dual-phase nanocomposites In situ transmission electron microscopy Multi-component alloy

Emerging two-dimensional Mo-based materials for rechargeable metal-ion batteries:Advances and perspectives

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第2期89卷 487-518,I0012页

作者： Qingqing Ruan Yuehua Qian Mengda Xue Lingyun Chen Qichun Zhang department of Applied Chemistry School of Chemistry and Chemical EngineeringChongqing UniversityChongqing 401331China department of Materials Science and engineering City University of Hong Kong999077Hong KongChina

With the rapid development of rechargeable metal-ion batteries(MIBs)with safety,stability and high energy density,significant efforts have been devoted to exploring high-performance electrode materials.In recent years,two-dimensional(2D)molybdenum-based(Mo-based)materials have drawn considerable attention due to their exceptional characteristics,including low cost,unique crystal structure,high theoretical capacity and controllable chemical compositions.However,like other transition metal compounds,Mo-based materials are facing thorny challenges to overcome,such as slow electron/ion transfer kinetics and substantial volume changes during the charge and discharge processes.In this review,we summarize the recent progress in developing emerging 2D Mo-based electrode materials for MIBs,encompassing oxides,sulfides,selenides,carbides.After introducing the crystal structure and common synthesis methods,this review sheds light on the charge storage mechanism of several 2D Mo-based materials by various advanced characterization techniques.The latest achievements in utilizing 2D Mo-based materials as electrode materials for various MIBs(including lithium-ion batteries(LIBs),sodium-ion batteries(SIBs)and zinc-ion batteries(ZIBs))are discussed in detail.Afterwards,the modulation strategies for enhancing the electrochemical performance of 2D Mo-based materials are highlighted,focusing on heteroatom doping,vacancies creation,composite coupling engineering and nanostructure design.Finally,we present the existing challenges and future research directions for 2D Mo-based materials to realize high-performance energy storage systems.

关键词： Molybdenum-based materials Two-dimensional materials Lithium-ion batteries Sodium-ion batteries Zinc-ion batteries

Miniature tunable Airy beam optical meta-device

在线全文

学校读者我要写书评

暂无评论

Opto-Electronic Advances 2024年第2期7卷 5-12页

作者： Jing Cheng Zhang Mu Ku Chen Yubin Fan Qinmiao Chen Shufan Chen Jin Yao Xiaoyuan Liu Shumin Xiao Din Ping Tsai department of Electrical engineering City University of Hong KongKowloonHong Kong SAR 999077China State Key Laboratory of Terahertz and Millimeter Waves City University of Hong KongKowloonHong Kong SAR 999077China Centre for Biosystems Neuroscienceand NanotechnologyCity University of Hong KongKowloonHong Kong SAR 999077China Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information system Guangdong Provincial Key Laboratory of Semiconductor Optoelectronic Materials and Intelligent Photonic SystemsHarbin Institute of TechnologyShenzhen 518055China

Tunable Airy beams with controllable propagation trajectories have sparked interest in various fields,such as optical manipulation and laser fabrication.Existing research approaches encounter challenges related to insufficient compactness and integration feasibility,or they require enhanced tunability to enable real-time dynamic manipulation of the propagation trajectory.In this work,we present a novel method that utilizes a dual metasurface system to surpass these limitations,significantly enhancing the practical potential of the Airy beam.Our approach involves encoding a cubic phase profile and two off-axis Fresnel lens phase profiles across the two metasurfaces.The validity of the proposed strategy has been confirmed through simulation and experimental results.The proposed meta-device addresses the existing limitations and lays the foundation for broadening the applicability of Airy beams across diverse domains,encompassing light-sheet microscopy,laser fabrication,optical tweezers,etc.

关键词： metasurface miniature device tunable Airy beam tunable meta-device

A study of the effect of local scour on the flow field near the spur dike

在线全文

学校读者我要写书评

暂无评论

Theoretical & Applied Mechanics Letters 2024年第2期14卷 98-105页

作者： Yu-Tian Li Jie-Min Zhan Wing-hong Onyx Wai department of Industrial design School of Industrial Design and Ceramic ArtFoshan UniversityFoshan 528000China department of Applied Mechanics and engineering Shenzhen Campus of Sun Yat-sen UniversityShenzhen 518107China department of Civil and Environmental engineering The Hong Kong Polytechnic UniversityHong Kong 999077China

The flow field near a spur dike such as down flow and horseshoe vortex system(HVS)are susceptible to the topographic changes in the local scouring process,resulting in variation of the sediment transport with time.In this study,large eddy simulations with fixed-bed at different scouring stages were conducted to investigate the changes in flow field.The results imply that the bed deformation leads to an increase in flow rate per unit area,which represent the capability of sediment transportation by water,in the scour hole.Moreover,the intensity of turbulent kinetic energy and bimodal motion near the sand bed induced by the HVS were also varied.However,the peak moments between the two sediment transport mechanisms were different.Hence,understanding the complex feedback mechanism between topography and flow field is essential for the local scour problem.

关键词： Spur dike Local scour Large eddy simulation Down flow Horseshoe vortex system

Recent Advances in Electrochemical-Based Silicon Production Technologies with Reduced Carbon Emission

在线全文

学校读者我要写书评

暂无评论

Research 2024年第1期2023卷 209-236页

作者： Feng Tian Zhongya Pang Shen Hu Xueqiang Zhang Fei Wang Wei Nie Xuewen Xia Guangshi Li Hsien-Yi Hsu Qian Xu Xingli Zou Li Ji Xionggang Lu State Key Laboratory of advanced Special Steel&Shanghai Key Laboratory of advanced Ferrometallurgy&School of Materials Science and engineering Shanghai University99#Shangda RoadShanghai 200444China Center for Hydrogen Metallurgy Technology Shanghai UniversityShanghai 200444China State Key Laboratory of ASIC and system School of MicroelectronicsFudan University220#Handan RoadShanghai 200433China School of Energy and Environment Department of Materials Science and EngineeringCity University of Hong KongKowloon TongHong KongChina

Sustainable and low-carbon-emission silicon production is currently one of the main focuses for the metallurgical and materials science communities.Electrochemistry,considered a promising strategy,has been explored to produce silicon due to prominent advantages:(a)high electricity utilization efficiency;(b)low-cost silica as a raw material;and(c)tunable morphologies and structures,including films,nanowires,and nanotubes.This review begins with a summary of early research on the extraction of silicon by electrochemistry.Emphasis has been placed on the electro-deoxidation and dissolution–electrodeposition of silica in chloride molten salts since the 21st century,including the basic reaction mechanisms,the fabrication of photoactive Si films for solar cells,the design and production of nanoSi and various silicon components for energy conversion,as well as storage applications.Besides,the feasibility of silicon electrodeposition in room-temperature ionic liquids and its unique opportunities are evaluated.On this basis,the challenges and future research directions for silicon electrochemical production strategies are proposed and discussed,which are essential to achieve large-scale sustainable production of silicon by electrochemistry.

关键词： directions electrodeposition electricity

Efficient C-N coupling in electrocatalytic urea generation on copper carbonate hydroxide electrocatalysts

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第6期93卷 289-298,I0008页

作者： Yinuo Wang Yian Wang Qinglan Zhao hongming Xu Shangqian Zhu Fei Yang Ernest P.Delmo Xiaoyi Qiu Chi Song Juhee Jang Tiehuai Li Ping Gao MDanny Gu Minhua Shao advanced Materials Thrust The Hong Kong University of Science and Technology(Guangzhou)Guangzhou 511400GuangdongChina department of Chemical and Biological engineering The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina department of Materials Science and engineering Southern University of Science and Technology of Chin11088 Xueyuan BoulevardShenzhen 518055GuangdongChina Energy Institute and Chinese National Engineering Research Center for Control&Treatment of Heavy Metal PollutionThe Hong Kong University of Science and TechnologyKowloonHong KongChina department of Chemistry City University of Hong KongTat Chee AvenueKowloonHong KongChina

Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)_2CO_(3))as an efficient CO_(2)NO_(3)RR electrocatalyst with an impressive urea Faradaic efficiency of45.2%±2.1%and a high yield rate of 1564.5±145.2μg h~(-1)mg_(cat)~(-1).More importantly,H_(2) evolution is fully inhibited on this electrocatalyst over a wide potential range between-0.3 and-0.8 V versus reversible hydrogen electrode.Our thermodynamic simulation reveals that the first C-N coupling follows a unique pathway on Cu_2(OH)_2CO_(3) by combining the two intermediates,~*COOH and~*NHO.This work demonstrates that high selectivity and yield rate of urea can be simultaneously achieved on simple Cu-based electrocatalysts in CO_(2)NO_(3)RR,and provide guidance for rational design of more advanced catalysts.

关键词： Copper carbonate hydroxide Co-reduction Urea generation C-N coupling DFT calculation

Step‑by‑Step Modulation of Crystalline Features and Exciton Kinetics for 19.2%Efficiency Ortho‑Xylene Processed Organic Solar Cells

在线全文

学校读者我要写书评

暂无评论

Nano-Micro Letters 2024年第2期16卷 258-272页

作者： Bosen Zou Weiwei Wu Top Archie Dela Pena Ruijie Ma Yongmin Luo Yulong Hai Xiyun Xie Mingjie Li Zhenghui Luo Jiaying Wu Chuluo Yang Gang Li He Yan department of Chemistry department of Chemistry and hong kong Branch of Chinese National engineering Research Center for Tissue Restoration and Reconstruction The Hong Kong University of Science and TechnologyClear Water BayHong KongPeople’s Republic of China department of Electronic and Information engineering Research Institute for Smart Energy(RISE)Guangdong‑Hong Kong‑Macao(GHM)Joint Laboratory for Photonic‑Thermal‑Electrical Energy Materials and DevicesThe Hong Kong Polytechnic UniversityHung HomKowloonHong Kong 999077People’s Republic of China The hong kong university of Science and Technology Function HubAdvanced Materials ThrustNanshaGuangzhou 511400People’s Republic of China department of Applied Physics The Hong Kong Polytechnic UniversityHong KongPeople’s Republic of China Shenzhen Key Laboratory of New Information Display and Storage Materials College of Materials Science and EngineeringShenzhen UniversityShenzhen 518060People’s Republic of China

With plenty of popular and effective ternary organic solar cells(OSCs)construction strategies proposed and applied,its power conversion efficiencies(PCEs)have come to a new level of over 19%in single-junction devices.However,previous studies are heavily based in chloroform(CF)leaving behind substantial knowledge deficiencies in understanding the influence of solvent choice when introducing a third component.Herein,we present a case where a newly designed asymmetric small molecular acceptor using fluoro-methoxylated end-group modification strategy,named BTP-BO-3FO with enlarged bandgap,brings different morphological evolution and performance improvement effect on host system PM6:BTP-eC9,processed by CF and ortho-xylene(o-XY).With detailed analyses supported by a series of experiments,the best PCE of 19.24%for green solvent-processed OSCs is found to be a fruit of finely tuned crystalline ordering and general aggregation motif,which furthermore nourishes a favorable charge generation and recombination behavior.Likewise,over 19%PCE can be achieved by replacing spin-coating with blade coating for active layer deposition.This work focuses on understanding the commonly met yet frequently ignored issues when building ternary blends to demonstrate cutting-edge device performance,hence,will be instructive to other ternary OSC works in the future.

关键词： Organic solar cells Ternary design Solvent selection Flouro-methoxylated end group Morphological ordering

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

在线全文

学校读者我要写书评

暂无评论

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