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Low-frequency bandgap and vibration suppression mechanism of a novel square hierarchical honeycomb metamaterial

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Applied Mathematics and Mechanics(English Edition) 2024年第10期45卷 1841-1856页

作者： Xingjian DONG Shuo WANG Anshuai WANG Liang WANG Zhaozhan ZHANG Yuanhao TIE Qingyu LIN Yongtao SUN State Key Laboratory of Mechanical systems and Vibration Shanghai Jiao Tong UniversityShanghai 200240China department of Mechanics Tianjin UniversityTianjin 300350China Tianjin Key Laboratory of Nonlinear Dynamics and control Tianjin UniversityTianjin 300350China School of Mechanical and Automotive Engineering Guangxi University of Science and TechnologyLiuzhou 545006Guangxi Zhuang Autonomous RegionChina

The suppression of low-frequency vibration and noise has always been an important issue in a wide range of engineering *** address this concern,a novel square hierarchical honeycomb metamaterial capable of reducing low-frequency noise has been *** combining Bloch’s theorem with the finite element method,the band structure is *** results indicate that this metamaterial can produce multiple low-frequency bandgaps within 500 Hz,with a bandgap ratio exceeding 50%.The first bandgap spans from 169.57 Hz to 216.42 *** reveal the formation mechanism of the bandgap,a vibrational mode analysis is *** analysis demonstrates that the bandgap is attributed to the suppression of elastic wave propagation by the vibrations of the structure’s two protruding corners and overall expansion ***,detailed parametric analyses are conducted to investigate the effect ofθ,i.e.,the angle between the protruding corner of the structure and the horizontal direction,on the band structures and the total effective bandgap *** is found that reducingθis conducive to obtaining lower frequency *** propagation characteristics of elastic waves in the structure are explored by the group velocity,phase velocity,and wave propagation ***,the transmission characteristics of a finite periodic structure are investigated *** results indicate significant acceleration amplitude attenuation within the bandgap range,confirming the structure’s excellent low-frequency vibration suppression capability.

关键词： wave propagation vibration suppression metamaterial low-frequency bandgap

Prescribed-time leader-following consensus of linear multi-agent systems by bounded linear time-varying protocols

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Science China(Information Sciences) 2024年第1期67卷 140-153页

作者： Kai ZHANG Bin ZHOU Xuefei YANG Guangren DUAN Center for control Theory and Guidance Technology Harbin Institute of Technology

This paper considers the prescribed-time leader-following consensus problem of input-constrained linear multi-agent systems under generally directed communication topology in two cases:the Laplacian matrix related to the entire communication topology between agents is either known or *** particular,the consensus problem for the former case is solved by a novel bounded linear time-varying(LTV) protocol,where the feedback gain is formulated by the parametric Lyapunov equation and the knowledge of the Laplacian ***,by utilizing a distributed observer,a fully bounded LTV protocol is proposed for the latter *** should be noted that,compared with the existing results,the system under consideration is more general,the designed protocols are linear,and the consensus problem is accomplished even in a fully distributed ***,the effectiveness of the proposed approach is verified by a numerical example.

关键词： leader-following consensus time-vary feedback prescribed-time control fully distributed consensus

A Temporary Frequency Response Strategy Using a Voltage Source-Based PermanentMagnet Synchronous Generator and Energy Storage systems

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Energy Engineering 2024年第2期121卷 541-555页

作者： Baogang Chen Fenglin Miao Jing Yang Chen Qi Wenyan Ji CSIC HaiZhuangWindpower Co. Ltd.Chongqing400000China State Key Laboratory of Operation and control of Renewable Energy&Storage systems China Electric Power Research InstituteBeijing100000China

Energy storage systems(ESS)and permanent magnet synchronous generators(PMSG)are speculated to be able to exhibit frequency regulation capabilities by adding differential and proportional control loops with different control *** available PMSG kinetic energy and charging/discharging capacities of the ESS were *** improve the inertia response and frequency control capability,we propose a short-term frequency support strategy for the ESS and *** this end,the weights were embedded in the control loops to adjust the participation of the differential and proportional controls based on the system frequency *** effectiveness of the proposed control strategy was verified using PSCAD/*** simulations revealed that the proposed strategy could improve the maximum rate of change of the frequency nadir and maximum frequency ***,it provides a promising solution of ancillary services for frequency regulation of PMSG and ESS.

关键词： Inertial control PMSG ESS wind power generation frequency support

Relaxed Stability Criteria for Time-Delay systems:A Novel Quadratic Function Convex Approximation Approach

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IEEE/CAA Journal of Automatica Sinica 2024年第4期11卷 996-1006页

作者： Shenquan Wang Wenchengyu Ji Yulian Jiang Yanzheng Zhu Jian Sun College of Electrical and Electronic Engineering Changchun University of TechnologyChangchun 130012China the College of Electrical Engineering and Automation Shandong University of Science and TechnologyQingdao 266590China Key Laboratory of Complex systems Intelligent control and Decision Beijing Institute of TechnologyBeijing 100081China

This paper develops a quadratic function convex approximation approach to deal with the negative definite problem of the quadratic function induced by stability analysis of linear systems with time-varying *** introducing two adjustable parameters and two free variables,a novel convex function greater than or equal to the quadratic function is constructed,regardless of the sign of the coefficient in the quadratic *** developed lemma can also be degenerated into the existing quadratic function negative-determination(QFND)lemma and relaxed QFND lemma respectively,by setting two adjustable parameters and two free variables as some particular ***,for a linear system with time-varying delays,a relaxed stability criterion is established via our developed lemma,together with the quivalent reciprocal combination technique and the Bessel-Legendre *** a result,the conservatism can be reduced via the proposed approach in the context of constructing Lyapunov-Krasovskii functionals for the stability analysis of linear time-varying delay ***,the superiority of our results is illustrated through three numerical examples.

关键词： Equivalent reciprocal combination technique quadratic function convex approximation approach stability timevarying delay

Molecular Investigation of Theileria in Ixodid Ticks from Changzhi,Shanxi Province,China

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Biomedical and Environmental Sciences 2024年第8期37卷 922-925页

作者： Jia Cui Hua Xiang Rao Yiping Liu Dongmei Li Juan Yu department of Microbiology of Basic Medical Sciences Changzhi Medical CollegeChangzhi 046000ShanxiChina department of Epidemiology and Health Statistics of Public Health and Preventive Medicine Changzhi Medical CollegeChangzhi 046000ShanxiChina department of Medical parasitology of Basic Medical Sciences Changzhi Medical CollegeChangzhi 046000ShanxiChina department of Vector Biology and control National Institute for Communicable Disease Control and PreventionChinese Center for Disease Control and PreventionBeijing 102206China

Theileria is a tick-borne intracellular protozoan that typically parasitizes erythrocytes,lymphocytes,and macrophages and causes acute clinical symptoms in host animals,including high fever,anemia,jaundice,and swelling of superficial lymph nodes[1].Theileriosis can lead to high mortality rates,and its rising global prevalence has resulted in significant economic losses to livestock husbandry and the national economy[2].

关键词： husbandry swelling typically

Distributed algorithm for solving variational inequalities over time-varying unbalanced digraphs

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control Theory and Technology 2024年第3期22卷 431-441页

作者： Yichen Zhang Yutao Tang Zhipeng Tu Yiguang Hong School of Artificial Intelligence Beijing University of Posts and TelecommunicationsBeijing 100876China Network Technology Laboratory Huawei Technologies Co.Ltd.Beijing 100095China department of control Science and Engineering Tongji UniversityShanghai 200092China Shanghai Research Institute for Intelligent Autonomous systems Tongji UniversityShanghai 200092China

In this paper,we study a distributed model to cooperatively compute variational inequalities over time-varying directed ***,each agent has access to a part of the full mapping and holds a local view of the global set *** virtue of an auxiliary vector to compensate the graph imbalance,we propose a consensus-based distributed projection algorithm relying on local computation and communication at each *** show the convergence of this algorithm over uniformly jointly strongly connected unbalanced digraphs with nonidentical local *** also provide a numerical example to illustrate the effectiveness of our algorithm.

关键词： Variational inequality Distributed computation Multi-agent system Weight-unbalanced graph

An Improved Method for Approximating the Infinite-Horizon Value Function of the Discrete-Time Switched LQR Problem

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Journal of systems Science & Complexity 2024年第1期37卷 22-39页

作者： HOU Tan LI Yuanlong LIN Zongli department of Automation Shanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of System control and Information Processing Ministry of Education of ChinaShanghai 200240China Shanghai Engineering Research Center of Intelligent control and Management Shanghai 200240China Charles L.Brown department of Electrical and Computer Engineering University of VirginiaCharlottesvilleVA 22904-4743USA

This paper considers the problem of approximating the infinite-horizon value function of the discrete-time switched LQR *** particular,the authors propose a new value iteration method to generate a sequence of monotonically decreasing functions that converges exponentially to the value *** method facilitates us to use coarse approximations resulting from faster but less accurate algorithms for further value iteration,and thus,the proposed approach is capable of achieving a better approximation for a given computation time compared with the existing *** numerical examples are presented in this paper to illustrate the effectiveness of the proposed method.

关键词： Optimal control switched linear systems switched LQR problem.

Study of Flow and Heat Transfer in an Ejector-Driven Swirl Anti-Icing Chamber

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Fluid Dynamics & Materials Processing 2024年第5期20卷 989-1014页

作者： Yi Tu Yuan Wu Yu Zeng Hunan University of Arts and Sciences Hunan Key Laboratory of Distributed Electric Propulsion Vehicle Control TechnologyChangde415000China Liaoning Provincial Key Laboratory of aircraft Ice Protection AVIC Aerodynamics Research InstituteShenyang110034China School of Aeronautic Science and Engineering Beihang UniversityBeijing100191China

The formation of ice on the leading edge of aircraft engines is a serious issue,as it can have catastrophic *** Swirl Anti-Icing(SAI)system,driven by ejection,circulates hot fluid within a 360°annular chamber to heat the engine inlet lip surface and prevent *** study employs a validated Computational Fluid Dynamics(CFD)approach to study the impact of key geometric parameters of this system on flow and heat transfer characteristics within the anti-icing ***,the entropy generation rate and exergy efficiency are analyzed to assess the energy utilization in the *** research findings indicate that,within the considered flow range,reducing the nozzle specific areaφfrom 0.03061 to 0.01083 can enhance the ejection coefficient by over 60.7%.This enhancement increases the air circulating rate,thereby intensifying convective heat transfer within the SAI ***,the reduction inφalso leads to a significant increase in the required bleed air pressure and a higher entropy generation rate,indicating lower exergy *** nozzle angleθnotably affects the distribution of hot and cold spots on the lip surface of the SAI ***θfrom 0°to 20°reduces the maximum temperature difference on the anti-icing chamber surface by 60 K.

关键词： Swirl anti-icing heat transfer exergy efficiency hot and cold spot aircraft engine

Editorial:special issue on analysis and control of complex systems in honor of the 90th birthday of Professor Huashu Qin

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control Theory and Technology 2024年第3期22卷 343-344页

作者： Yiguang Hong Shengwei Mei Ping Yang department of control Science and Engineering Tongji UniversityShanghai200092China Shanghai Research Institute for Intelligent Autonomous systems Tongji UniversityShanghai200092China department of Electrical Engineering and Applied Electronics Technology Tsinghua UniversityBeijing100084China School of Electric Power South China University of TechnologyGuangzhou510640GuangdongChina

It is our great pleasure to organize this special issue in control Theory and Technology in honor of the 90th birthday of Professor Huashu *** is one of the pioneers in control theory and applications in China,and has made many truly outstanding contributions to the field including nonlinear dynamics and control,intelligent control,robotics and complex *** is no surprise that she was selected as a representative introduced significantly in“Women in control”of IEEE control systems Magazine.

关键词： control honor analysis