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Dynamics of cantilever plates and its hybrid vibration control

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Acta Mechanica Sinica 2013年第5期29卷 738-748页

作者： bo Ni Chao hu School of Aerospace Engineering and Applied Mechanics Tongji University Shanghai Institute of Spaceflight Fundamental Technology College of Civil Science and Engineering Yangzhou University

Applying Lagrange-Germain＇s theory of elas- tic thin plates and Hamiltonian formulation, the dynamics of cantilever plates and the problem of its vibration control are studied, and a general solution is finally given. Based on Hamiltonian and Lagrangian density function, we can obtain the flexural wave equation of the plate and the relationship between the transverse and the longitudinal eigenvalues. Based on eigenfunction expansion, dispersion equations of propagation mode of cantilever plates are deduced. By satisfying the boundary conditions of cantilever plates, the natural frequencies of the cantilever plate structure can be given. Then, analytic solution of the problem in plate structure is obtained. An hybrid wave/mode control approach, which is based on both independent modal space control and wave control methods, is described and adopted to analyze the active vibration control of cantilever plates. The low-order （controlled by modal control） and the high-order （controlled by wave control） frequency response of plates are both improved. The control spillover is avoided and the robustness of the system is also improved. Finally, simulation results are analyzed and discussed.

关键词： Cantilever plate Hamiltonian formulism - Dis- persion equations Modal control Elastic wave control - Hybrid control

Variable Stiffness Identification and Configuration Optimization of Industrial Robots for Machining Tasks

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Chinese Journal of Mechanical Engineering 2022年第5期35卷 275-290页

作者： Jiachen Jiao Wei Tian lin Zhang bo li Junshan hu Yufei li Dawei li Jianlong Zhang Nanjing University of Aeronautics and Astronautics Nanjing 210016China Beijing Institute of Space Launch Technology Beijing 100076China Beijing Institute of Mechanical Equipment Beijing 100854China

Industrial robots are increasingly being used in machining tasks because of their high flexibility and ***,the low structural stiffness of a robot significantly affects its positional accuracy and the machining quality of its operation *** robot stiffness characteristics and optimization methods is an effective method of improving the stiffness performance of a ***,aiming at the poor accuracy of stiffness modeling caused by approximating the stiffness of each joint as a constant,a variable stiffness identification method is proposed based on space ***,a task-oriented axial stiffness evaluation index is proposed to quantitatively assess the stiffness performance in the machining *** addition,by analyzing the redundant kinematic characteristics of the robot machining system,a configuration optimization method is further developed to maximize the *** numerous points or trajectory-processing tasks,a configuration smoothing strategy is proposed to rapidly acquire optimized ***,experiments on a KR500 robot were conducted to verify the feasibility and validity of the proposed stiffness identification and configuration optimization methods.

关键词： Industrial robot Space gridding Variable stiffness identification Configuration optimization Smooth processing

A New Methodology for Early Detection of Thermoacoustic Combustion Oscillations Based on Permutation Entropy

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Journal of Thermal Science 2023年第6期32卷 2310-2320页

作者： li Yao hu Chunyan SHEN Youhao HAN bo YANG Jinhu XU Gang Key Laboratory of light Duty Gas Turbine Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China Innovation Academy for light-Duty Gas Turbine Chinese Academy of SciencesBeijing100190China

We carry out a series of experimental investigations in a model combustor to detect a precursor of thermoacoustic combustion oscillations based on permutation entropy,which can amplify the subtle changes effected in the time sequence to identify the *** changing the flame’s location or the fuel flow to a value,an abrupt switch from aperiodic small-amplitude oscillations to periodic large-amplitude oscillations would occur in pressure *** characteristic frequency of combustion oscillation is obtained by spectral analysis,with which a modified algorithm of the permutation entropy is *** impact evaluation on key parameters such as moving step sizes and window sizes reveals that the moving data permutation entropy has strong robustness,and can accurately detect the onset of thermoacoustic *** nonlinear analysis exhibits peculiar dynamics of the combustion system,which result in specific patterns in the time series and provide a theoretical basis for anomaly *** results suggest that the permutation entropy has a certain potential in early warning and detection of combustion oscillations.

关键词： thermoacoustic combustion oscillation permutation entropy moving data anomaly detection precursors

Fixed-Time Antidisturbance Consensus Tracking for Nonlinear Multiagent Systems With Matching and Mismatching Disturbances

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IEEE/CAA Journal of Automatica Sinica 2024年第6期11卷 1410-1423页

作者： Xiangmin Tan Chunyan hu Guanzhen Cao Qinglai Wei Wei li bo Han Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190 School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing 100049China Institute of Automation Chinese Academy of SciencesBeijing 100190 School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100049China IEEE

In this paper,fixed-time consensus tracking for mul-tiagent systems(MASs)with dynamics in the form of strict feed-back affine nonlinearity is addressed.A fixed-time antidistur-bance consensus tracking protocol is proposed,which consists of a distributed fixed-time observer,a fixed-time disturbance observer,a nonsmooth antidisturbance backstepping controller,and the fixed-time stability analysis is conducted by using the Lyapunov theory *** paper includes three main ***,a distributed fixed-time observer is developed for each follower to obtain an estimate of the leader’s output by utilizing the topology of the communication ***,a fixed-time disturbance observer is given to estimate the lumped disturbances for feedforward ***,a nonsmooth antidisturbance backstepping tracking controller with feedforward compensation for lumped disturbances is *** order to mitigate the“explosion of complexity”in the tradi-tional backstepping approach,we have implemented a modified nonsmooth command filter to enhance the performance of the closed-loop *** simulation results show that the pro-posed method is effective.

关键词： Antidisturbance backstepping consensus tracking fixed-time stability multiagent system(MASs) strict feedback affine nonlinear systems.

Few-layered ReS_2 nanosheets grown on graphene as electrocatalyst for hydrogen evolution reaction

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Rare Metals 2018年第12期37卷 1014-1020页

作者： Han Gao hu-hu Yue Fei Qi bo Yu Wan-li Zhang Yuan-Fu Chen State Key Laboratory of Electronic Thin Films and Integrate Devices Univrsity of Electronic Science and Technology of China School of Optoelectronic Engineering Chongqing University of Posts and Telecommunications

Few-layered ReStwo-dimensional(2 D) semiconductor nanosheets directly nucleated and grown on reduced graphene oxide(RGO) were synthesized through a facile hydrothermal method. Compared with bare ReS, the ReS2/RGO hybrid delivers much better electrocatalytic activity for hydrogen evolution reaction(HER) in acidic media. It exhibits a lower Tafel slope of 107.4 mV decand a larger current density of-5.2 mA·cmat-250 mV(vs. RHE),compared with ReS(152.7 mV·dec,-3.1 mA·cm). The ReS/RGO hybrid has a unique architecture constructed by highly conductive and porous RGO internetworks, which guarantees easy electrolyte infiltration and efficient charge transfer and provides sufficient active edge sites, resulting in enhanced HER performance. The present synthesis approach can be extended to synthesize other 2 D-semiconductor-based composites for energy storage and catalytic devices.

关键词： ReS_2/RGO Hydrothermal method Electrocatalyst Hydrogen evolution reaction

Discrete element simulation of effects of multicontact loading on single particle crushing

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Particuology 2022年第10期20卷 49-60页

作者： Chuanfeng Fang Zhihong Nie Jian Gong bo li Wei hu Ashiru Mohammed School of Civil Engineering Central South UniversityChangsha 410075China College of Civil of Engineering and Architecture Guangxi UniversityNanning530004China College of Architecture and Civil Engineering Wenzhou UniversityWenzhou 325035China hunan Province Key Laboratory of Geotechnical Engineering Stability Control and Health Monitoring Hunan University of Science and TechnologyXiangtan411201China

Particle crushing commonly occurs in granular materials and affects their structures and mechanical *** idealized particles in experimental single particle crushing tests with two loading points,natural particles are crushed under multicontact *** date,the criteria and patterns of par-ticle crushing under multicontact conditions are not fully *** using the three-dimensional discrete element method,this report explores the effect of multicontact loading on the crushing criterion of a single particle,the crushing pattern,and the relationship between the particle crushing strength and loading *** particles are modelled as aggregates of glued Voronoi *** numer-ical results indicate that the logarithm of the mean principal stress has a good linear correlation with the coordination *** a specific coordination number,the number of child particles presents a significant normal *** a specific number of child particles,the volumes of child particles can be statistically described as normal or gamma *** typical models are proposed to qual-itatively analyse the relationship between the loading distribution and crushing *** relevant conclusions can be helpful in engineering practice and in further studies on crushable granular materials via the discrete element method.

关键词： DEM Multiple contacts Particle crushing Crushing criterion Crushing pattern Loading distribution

Numerical investigation of the effect of wedge-type cavitating-bubble generator on attached unsteady cavitating flows using proper orthogonal decomposition method

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Journal of Hydrodynamics 2023年第2期35卷 314-329页

作者： bo-jie Hong Chang-li hu Zhi-ying Wang Hao-jie Xing School of Energy and Power Engineering Nanjing University of Science and TechnologyNanjing210094China Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing100190China

The objective of this work is to reveal the effect of a passive control method called wedge-type cavitating-bubble generator(WCG)on the cloud cavitation dynamics of National Advisory Committee for Aeronautics(NACA)66 *** simulations are performed using the Partially-averaged Navier-Stokes(PANS)method coupled with the Zwart cavitation *** proper orthogonal decomposition(POD)method is applied to extract the dominant flow *** results show that the WCG can induce the attached cavity to occur just behind the WCG instead of the hydrofoil leading *** the periodical time-evolution process of the unsteady cavity,it is found that the attached cavity with a larger scale around the hydrofoil with WCG has a rougher surface,accompanied with more shedding behaviors of small *** is further illustrated by the POD modes,that is,the mode 1 and modes 2–4 present the large and small cavity vortex structures ***,the dominant frequencies of 50 Hz,47.5 Hz are given by the POD method respectively for the hydrofoils without and with WCG,which is in good agreement with that of FFT *** addition,the correlation distribution of POD modal coefficients shows that the WCG can strengthen the vortex energy as well as the turbulence intensity.

关键词： Cavitating-bubble generator proper orthogonal decomposition(POD) attached cavity vortex structures

Effect of microstructure on corrosion behavior of high strength martensite steel-A literature review

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International Journal of Minerals,Metallurgy and Materials 2021年第5期28卷 754-773页

作者： li Wang Chao-fang Dong Cheng Man Ya-bo hu Qiang Yu Xiao-gang li Beijing Advanced Innovation Center for Materials Genome Engineering Key Laboratory for Corrosion and Protection(MOE)Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing 100083China School of Materials Science and Engineering Ocean University of ChinaQingdao 266100China hunan Valin lianyuan Iron and Steel Co.Ltd Loudi 417009China

The high strength martensite steels are widely used in aerospace,ocean engineering,etc.,due to their high strength,good ductility and acceptable corrosion *** paper provides a review for the influence of microstructure on corrosion behavior of high strength martensite *** is the most common corrosion type of high strength stainless steels,which always occurs at weak area of passive film such as inclusions,carbide/intermetallic ***,the chromium carbide precipitations in the martensitic lath/prior austenite boundaries always result in intergranular *** precipitation,dislocation and grain/lath boundary are also used as crack nucleation and hydrogen traps,leading to hydrogen embrittlement and stress corrosion cracking for high strength martensite ***,the retained/reversed austenite has beneficial effects on the corrosion resistance and could reduce the sensitivity of stress corrosion cracking for high strength martensite ***,the corrosion mechanisms of additive manufacturing high strength steels and the ideas for designing new high strength martensite steel are explored.

关键词： corrosion behavior high strength martensite steel microstructure additive manufacturing

致羔羊腹泻奇异变形杆菌的分离鉴定及迁徙行为分析

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中国兽医学报 2017年第7期37卷 1274-1282页

作者：周建波胡丽萍马宁宁董雯雯邵明旭朱丽君魏凯朱瑞良山东农业大学动物科技学院/山东省动物生物技术与疫病防治重点实验室山东泰安271018 山东省动物疫病预防与控制中心山东济南250022

2015年春,山东滕州某规模化羊场新生羔羊出现严重的腹泻,并且部分羔羊死亡。对该羊场病死羔羊进行剖检后,共分离到4株细菌(分别命名为PM1、PM2、PM3、PM4)。对所分离的细菌进行形态特征、生化试验以及16S rDNA遗传分析,判定该4株菌均为... 详细信息

2015年春,山东滕州某规模化羊场新生羔羊出现严重的腹泻,并且部分羔羊死亡。对该羊场病死羔羊进行剖检后,共分离到4株细菌(分别命名为PM1、PM2、PM3、PM4)。对所分离的细菌进行形态特征、生化试验以及16S rDNA遗传分析,判定该4株菌均为奇异变形杆菌。16SrDNA系统发育及同源性分析显示:4株分离菌与其他11株奇异变形杆菌的同源性为99%以上,其中与中国hu株、马来西亚PPB3株以及印度BAB-199株位于同一个分支上,且与中国的hu株的进化关系最近;4株分离菌之间的同源性为100%,判断为同1株菌。细菌生长曲线、药敏试验、毒力试验、毒素测定试验以及游散行为分析结果表明,该分离菌于14h左右达到生长稳定期,且对环丙沙星、左氟沙星最为敏感;对小鼠有强致病性,分离菌培养液的无菌滤液对小鼠无毒性作用;在含0.5%琼脂的LB平板上迁徙速度最快,且在含琼脂1.5%和2.0%的LB平板上呈圆环样周期运动。该研究结果为羊奇异变形杆菌病的防控提供了基础。

关键词：羔羊奇异变形杆菌分离鉴定 16SrDNA 系统发育分析迁徙行为