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Dirac method for nonlinear and non-homogenous boundary value problems of plates

Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 15-38页

作者： Xiaoye MAO Jiabin WU Junning ZHANG Hu DING Liqun CHEN Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Frontier Science Center of MechanoinformaticsShanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200444China Shanghai Institute of Aircraft Mechanics and control Shanghai 200092China

The boundary value problem plays a crucial role in the analytical investigation of continuum dynamics. In this paper, an analytical method based on the Dirac operator to solve the nonlinear and non-homogeneous boundary value problem of rectangular plates is proposed. The key concept behind this method is to transform the nonlinear or non-homogeneous part on the boundary into a lateral force within the governing function by the Dirac operator, which linearizes and homogenizes the original boundary, allowing one to employ the modal superposition method for obtaining solutions to reconstructive governing equations. Once projected into the modal space, the harmonic balance method(HBM) is utilized to solve coupled ordinary differential equations(ODEs)of truncated systems with nonlinearity. To validate the convergence and accuracy of the proposed Dirac method, the results of typical examples, involving nonlinearly restricted boundaries, moment excitation, and displacement excitation, are compared with those of the differential quadrature element method(DQEM). The results demonstrate that when dealing with nonlinear boundaries, the Dirac method exhibits more excellent accuracy and convergence compared with the DQEM. However, when facing displacement excitation, there exist some discrepancies between the proposed approach and simulations;nevertheless, the proposed method still accurately predicts resonant frequencies while being uniquely capable of handling nonuniform displacement excitations. Overall, this methodology offers a convenient way for addressing nonlinear and non-homogenous plate boundaries.

关键词： rectangular plate Dirac operator nonlinear boundary time-dependent boundary boundary value problem

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An Underwater Biomimetic Robot that can Swim,Bipedal Walk and Grasp

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Journal of Bionic Engineering 2024年第3期21卷 1223-1237页

作者： Qiuxuan Wu Liwei Pan FuLin Du ZhaoSheng Wu XiaoNi Chi FaRong Gao Jian Wang Anton A.Zhilenkov School of Automation Hangzhou Dianzi UniversityHangzhou310018China International Joint Research Laboratory for Autonomous Robotic systems Hangzhou310018China GEELY Automotive Institute Hangzhou Vocational and Technical CollegeHangzhou310018China Institute of Hydrodynamics and control Processes Sankt-Petersburg Saint Petersburg State Marine Technical UniversitySankt-PetersburgRussia

In developing and exploring extreme and harsh underwater environments,underwater robots can effectively replace humans to complete *** meet the requirements of underwater flexible motion and comprehensive subsea operation,a novel octopus-inspired robot with eight soft limbs was designed and *** robot possesses the capabilities of underwater bipedal walking,multi-arm swimming,and grasping *** closely interact with the underwater seabed environment and minimize disturbance,the robot employs a cable-driven flexible arm for its walking in underwater floor through a bipedal walking *** multi-arm swimming offers a means of three-dimensional spatial movement,allowing the robot to swiftly explore and navigate over large areas,thereby enhancing its ***,the robot’s walking arm enables it to grasp and transport objects underwater,thereby enhancing its practicality in underwater environments.A simplified motion models and gait generation strategies were proposed for two modes of robot locomotion:swimming and walking,inspired by the movement characteristics of octopus-inspired multi-arm swimming and bipedal *** experimental verification,the robot’s average speed of underwater bipedal walking reaches 7.26 cm/s,while the horizontal movement speed for multi-arm swimming is 8.6 cm/s.

关键词： Underwater soft robots Underwater bipedal walking Multi-arm swimming Cable drive

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Quantum phase transition of the Jaynes-Cummings model

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 1-9页

作者： Cheng Liu Jin-Feng Huang Key Laboratory of Low-Dimensional Quantum Structures and Quantum control of Ministry of Education Key Laboratory for Matter Microstructure and Function of Hunan ProvinceDepartment of Physics and Synergetic Innovation Center for Quantum Effects and ApplicationsInstitute of Interdisciplinary StudiesHunan Normal UniversityChangsha 410081China

Herein,we propose an experimentally feasible scheme to show the quantum phase transition of the Jaynes-Cummings(JC)model by modulating the transition frequency of a two-level system in a quantum Rabi model with strong *** tuning the modulation frequency and amplitude,the ratio of the effective coupling strength of the rotating terms to the effective cavity(atomic transition)frequency can enter the deep-strong coupling regime,while the counter-rotating terms can be ***,a deep-strong JC model is *** ratio of the coupling strength to resonance frequencies in the deep-strong JC model is two orders of magnitude larger than the corresponding ratio in the original quantum Rabi *** scheme can be employed in atom-cavity resonance and off-resonance cases,and it is valid over a broad *** nonzero average cavity photons of the ground state indicate the emergence of a quantum phase ***,we demonstrate the dependence of the phase diagram on the atom-cavity detuning and modulation *** the parameters used in our scheme are within the reach of current experimental *** scheme provides a new mechanism for investigating the critical phenomena of finite-sized systems without requiring classical field limits,thereby opening a door for studying fundamental quantum phenomena occurring in the ultrastrong and even deep-strong coupling regimes.

关键词： Jaynes-Cummings model quantum phase transition frequency modulation

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Valuation and comparison of the actual and optimal control strategy in an emerging infectious disease:Implication from a COVID-19 transmission model

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Infectious Disease Modelling 2024年第2期9卷 354-372页

作者： Lili Liu Xi Wang Ou Liu Yazhi Li Zhen Jin Sanyi Tang Xia Wang Shanxi Key Laboratory of Mathematical Techniques and Big Data Analysis on Disease control and Prevention Complex Systems Research CenterShanxi UniversityTaiyuan030006China School of Mathematical Sciences Shanxi UniversityTaiyuan030006China School of Mathematics and Statistics Qiannan Normal University for NationalitiesGuizhouDuyun558000China School of Mathematics and Statistics Shaanxi Normal UniversityXi'an710119China

To effectively combat emerging infectious diseases like COVID-19,it is crucial to adopt strict prevention and control measures promptly to effectively contain the spread of the *** this paper,we propose a transmission model to investigate the influence of two control strategies:reducing contact numbers and improving medical *** examine these strategies in terms of constant control and time-varying *** sensitivity analysis on two reproduction numbers of the model with constant control,we demonstrate that reducing contact numbers is more effective than improving medical ***,these two constant controls significantly influence the peak values and timing of ***,intensifying control measures can reduce peak values,albeit at the expense of delaying the peak *** the model with time-varying control,we initially explore the corresponding optimal control problem and derive the characteristic expression of optimal ***,we utilize real data from January 10th to April 12th,2020,in Wuhan city as a case study to perform parameter estimation by using our proposed improved *** findings illustrate that implementing optimal control measures can effectively reduce infections and deaths,and shorten the duration of the ***,we numerically explore that implementing control measures promptly and increasing intensity to reduce contact numbers can make actual control be more closer to optimized ***,we utilize the real data from October 31st to November 18th,2021,in Hebei province as a second case study to validate the feasibility of our proposed suggestions.

关键词： Emerging epidemic Transmission model Sensitivity analysis Actual control Optimal control

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Leader-Following Consensus of Multi-Agent systems via Fully Distributed Event-Based control

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Journal of Shanghai Jiaotong university(Science) 2024年第4期29卷 640-645页

作者： GENG Zongsheng ZHAO Dongdong ZHOU Xingwen YAN Lei YAN Shi School of Information Science and Engineering Lanzhou UniversityLanzhou730000China Engineering Research center of Open-Source Software and Real-Time systems of Ministry of Education Lanzhou UniversityLanzhou730000China

This paper aims to study the leader-following consensus of linear multi-agent systems on undirected ***,we construct an adaptive event-based protocol that can be implemented in a fully distributed way by using only local relative *** protocol is also resource-friendly as it will be updated only when the agent violates the designed event-triggering function.A sufficient condition is proposed for the leader-following consensus of linear multi-agent systems based on the Lyapunov approach,and the Zeno-behavior is ***,two numerical examples are provided to illustrate the effectiveness of the theoretical results.

关键词： consensus multi-agent systems event-based control adaptive control fully distributed protocol

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Geometrical transition properties of vortex cavitation and associated flow-choking characteristics in poppet valves

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第6期25卷 455-469页

作者： Liang LU Zhongdong LIANG Yuming LIU Zhipeng WANG Shohei RYU School of Mechanical Engineering Tongji UniversityShanghai 201804China Frontiers Science center for Intelligent Autonomous systems Tongji UniversityShanghai 201210China Technical Research Laboratory Hitachi Construction Machinery Co.Ltd.Tsuchiura 300-0013Japan

Poppet valves have become increasingly significant in ensuring precise digital flow rate and pressure control in hydraulic systems,necessitating a more profound understanding of the geometrical properties of cavitation in them,as well as associated flow-choking *** a comparative analysis with experimentally observed cavity images,we found that large eddy simulation(LES)turbulence modeling effectively replicates the geometrical properties of cavitation in these *** analysis demonstrated that cavitation is generated from vortices that result from the interaction between the notch contracta flow and the surrounding fluid *** in the internal or external vena contracta conditions result in fixed or discrete cavities,and the length-to-diameter ratio serves as a measure of the transition between internal and external vena contracta flow *** study establishes a threshold length-to-diameter ratio of approximately 2 for the tested poppet *** specifically,in notch structures with a smaller valve opening,longer sealing length,and smaller throttling angle(corresponding to a larger length-to-diameter ratio),the liquid-to-vapor transfer process is more evident than that in the reverse direction.A long-standing vapor cavity becomes fixed inside the notch,leading to a more pronounced flow-choking *** contrast,for structures with a smaller length-to-diameter ratio,the cavitation process for discrete vapor cavities is more complete,ensuring fluid flow continuity and significantly reducing the occurrence of the flow-choking phenomenon.

关键词： Poppet valves Vena contracta Vortex flow Vapor cavity Flow-choking

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Force Compensation control for Electro-Hydraulic Servo System with Pump-Valve Compound Drive via QFT-DTOC

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 228-246页

作者： Kaixian Ba Yuan Wang Xiaolong He Chunyu Wang Bin Yu Yaliang Liu Xiangdong Kong Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and control Qinhuangdao 066004China School of Mechanical Engineering Yanshan UniversityQinhuangdao 066004China National Engineering Research center for Local Joint of Advanced Manufacturing Technology and Equipment Yanshan UniversityQinhuangdao 066004China

Each joint of a hydraulic-driven legged robot adopts a highly integrated hydraulic drive unit(HDU),which features a high power-weight ***,most HDUs are throttling-valve-controlled cylinder systems,which exhibit high energy *** contrast,pump control systems offer a high ***,their response ability is *** fully utilize the advantages of pump and valve control systems,in this study,a new type of pump-valve compound drive system(PCDS)is designed,which can not only effectively reduce the energy loss,but can also ensure the response speed and response accuracy of the HDUs in robot joints to satisfy the performance requirements of ***,considering the force control requirements of energy conservation,high precision,and fast response of the robot joint HDU,a nonlinear mathematical model of the PCDS force control system is first *** addition,pressure-flow nonlinearity,friction nonlinearity,load complexity and variability,and other factors affecting the system are considered,and a novel force control method based on quantitative feedback theory(QFT)and a disturbance torque observer(DTO)is designed,which is denoted as QFT-DTOC *** method improves the control accuracy and robustness of the force control system,reduces the effect of the disturbance torque on the control performance of the servo motor,and improves the overall force control performance of the ***,experimental verification is performed using the PCDS performance test *** experimental results and quantitative data show that the QFT-DTOC proposed herein can significantly improve the force control performance of the *** relevant force control method can be used as a bottom-control method for the hydraulic servo system to provide a foundation for implementing the top-level trajectory planning of the robot.

关键词： Legged robot Pump-valve compound drive system(PCDS) Force compensation control Quantitative feedback theory(QFT) Disturbance torque observer(DTO)

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Characterization and quantification of multi-field coupling in lithium-ion batteries under mechanical constraints

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Journal of Energy Chemistry 2024年第8期95卷 364-379,I0009页

作者： Xue Cai Caiping Zhang Zeping Chen Linjing Zhang Dirk Uwe Sauer Weihan Li National Active Distribution Network Technology Research center Beijing Jiaotong UniversityBeijing 100044China Chair for Electrochemical Energy Conversion and Storage systems Institute for Power Electronics and Electrical Drives(ISEA)RWTH Aachen UniversityCampus Boulevard 8952074 AachenGermany center for Ageing Reliability and Lifetime Prediction of Electrochemical and Power Electronic Systems(CARL)Campus-Boulevard 8952074 AachenGermany Juelich Aachen Research Alliance JARA-EnergyAachenGermany Helmholtz Institute Münster(HI MS) IEK-12Forschungszentrum JülichGermany

The safety and durability of lithium-ion batteries under mechanical constraints depend significantly on electrochemical,thermal,and mechanical fields in *** and quantifying the multi-field coupling behaviors requires interdisciplinary ***,we design experiments under mechanical constraints and introduce an in-situ analytical framework to clarify the complex interaction mechanisms and coupling degrees among multi-physics *** proposed analytical framework integrates the parameterization of equivalent models,in-situ mechanical analysis,and quantitative assessment of coupling *** results indicate that the significant impact of pressure on impedance at low temperatures results from the diffusion-controlled step,enhancing kinetics when external pressure,like 180 to 240 k Pa at 10℃,is *** diversity in control steps for the electrochemical reaction accounts for the varying impact of pressure on battery performance across different *** thermal expansion rate suggests that the swelling force varies by less than 1.60%per unit of elevated temperature during the lithiation *** introducing a composite metric,we quantify the coupling correlation and intensity between characteristic parameters and physical fields,uncovering the highest coupling degree in electrochemical-thermal *** results underscore the potential of analytical approaches in revealing the mechanisms of interaction among multi-fields,with the goal of enhancing battery performance and advancing battery management.

关键词： Lithium-ion battery Muti-field coupling Mechanical constraints Interaction mechanisms Quantitative analysis

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Prevalence of nicotine dependence among smokers aged 40 years and older in China

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Chinese Medical Journal Pulmonary and Critical Care Medicine 2024年第2期2卷 119-131页

作者： Ying Ji Shu Cong Jing Fan Ning Wang Wenjing Wang Xuping Song Liwen Fang Chinese Field Epidemiology Training Program Chinese Center for Disease Control and Prevention27 Nanwei RoadXicheng DistrictBeijing 100050China National center for Chronic and Non-communicable Disease control and Prevention Chinese Center for Disease Control and Prevention27 Nanwei RoadXicheng DistrictBeijing 100050China Zunyi center for Disease control and Prevention ZunyiGuizhou 563000China

Background:Nicotine dependence,also known as tobacco dependence,is a common chronic disease and a major risk factor for chronic respiratory *** present study was designed to determine the prevalence of nicotine dependence and its changes among smokers aged 40 years and older in China,to analyze the characteristics of nicotine dependence among smokers,and to provide a reference for smoking cessation ***:The data were sourced from nationally representative large-sample surveys conducted during 2014-2015 and 2019-2020 in the Chinese population,covering 125 counties(districts)in 31 provinces,autonomous regions and *** related to smoking and nicotine dependence among residents≥40 years old were collected in face-to-face interviews.A total of 20,062 and 18,975 daily smokers were included in the 2014-2015 and 2019-2020 surveys,*** severity of nicotine dependence was evaluated according to the Fagerström Test for Nicotine Dependence and Heaviness of Smoking *** level and change in nicotine dependence among daily smokers aged≥40 years were estimated using a complex weighted sampling design,and their influencing factors were ***:Levels of nicotine dependence among daily smokers aged≥40 years in China could be divided into very low,low,medium,high,and very high,accounting for 31.1%,27.9%,13.4%,20.5%,and 7.1%of the total,*** average Fagerström Test for Nicotine Dependence score was 3.9(95%confidence interval[CI]:3.8-4.0),with the prevalence of medium-high nicotine dependence being 41.0%(95%CI:39.0-42.9%)and that of high and very high nicotine dependence being 27.6%(95%CI:26.0-29.3%),both of which were significantly higher in men than in women(both P<0.001).Among daily smokers,those with a low education level,age at smoking initiation<18 years,and with smoking duration of≥20 years had a higher degree of nicotine *** terms of geographic region,the level of medium-high nicotine d

关键词： Nicotine dependence Chronic obstructive pulmonary disease Surveillance Smoking cessation Tobacco control Distribution

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Process in laser drilling of deep microholes without taper on metal materials

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Science China(Technological Sciences) 2024年第1期67卷 37-59页

作者： FAN RunZe MEI XueSong CUI JianLei State Key Laboratory for Manufacturing systems Engineering Xi’an Jiaotong UniversityXi’an 710054China

Deep microhole machining is currently a prominent research area within the aerospace field,encompassing blade film cooling and fuel injection control ***,taper defects in metal materials may lead to performance degradation or even structural damage over a component’s *** and helical drilling,facilitated by ultrashort pulse lasers,have proven more suitable for achieving high-precision,deep holes in metal ***,excessive repetition rates can also result in severe thermal *** methods are commonly employed for controlling taper,including parameter optimization,assistance,and secondary *** laser beam drilling is widely utilized and has been integrated into relevant machining systems for commercial *** deep microholes include film cooling holes and injection *** drilling is a potential machining method for new materials in the aerospace *** laser drilling processing has been studied,numerous related scientific challenges and technical difficulties must be addressed before practical implementation.

关键词： aerospace laser drilling deep microhole taper control

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