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Finite-time consensus of heterogeneous multi-agent systems

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Chinese Physics B 2013年第3期22卷 550-555页

作者：朱亚锟关新平罗小元 Institute of Electrical Engineering Yanshan University

We investigate the finite-time consensus problem for heterogeneous multi-agent systems composed of first-order and second-order agents.A novel continuous nonlinear distributed consensus protocol is constructed,and finite-time consensus criteria are obtained for the heterogeneous multi-agent *** with the existing results,the stationary and kinetic consensuses of the heterogeneous multi-agent systems can be achieved in a finite time ***,the leader can be a first-order or a second-order integrator ***,some simulation examples are employed to verify the efficiency of the theoretical results.

关键词： heterogeneous multi-agent system finite-time consensus nonlinear consensus protocol

Influences of molybdenum substitution for cobalt on the phase structure and electrochemical kinetic properties of AB_5-type hydrogen storage alloys

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Journal of Rare Earths 2011年第7期29卷 692-697页

作者：杨淑琴韩树民宋建争李媛 State Key Laboratory of Metastable Materials Science and Technology Yanshan University College of Environmental and Chemical Engineering Yanshan University

The effects of the partial replacement of Co with Mo on the phase structure and electrochemical kinetic properties of La0.35Ce0.65Ni3.54Co0.80-xMn0.35Al0.32Mox （x=0.00, 0.10, 0.15, 0.20, 0.25） hydrogen storage alloys prepared by arc-melting method were sys-tematically studied in this paper. The X-ray diffraction （XRD） showed that after partial substitution of Mo for Co, the alloys remained a single LaNi5 phase with a hexagonal CaCu5-type structure. The P-C isotherms indicated that the equilibrium pressure gradually decreased with in-creasing of Mo content. Electrochemical studies showed that the substitution of Mo for Co could greatly increase discharge capacity, improve activation ability and reduce self-discharge of alloy electrodes. The alloy with x=0.25 exhibited a higher rate dischargeability （HRD1200= 50.9%）. Moreover, Mo is a vital element in favor of kinetic properties of AB5-type hydrogen storage alloys. As Mo content increased, the ex-change current density I0, the hydrogen diffusion rate gradually increased.

关键词： hydrogen storage alloys Mo substitution phase structure electrochemical kinetic characteristics rare earths

Type Synthesis of Two-Degrees-of-Freedom Rotational Parallel Mechanism with Two Continuous Rotational Axes

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Chinese Journal of Mechanical Engineering 2016年第4期29卷 694-702页

作者： XU Yundou ZHANG Dongsheng WANG Min YAO Jiantao ZHAO Yongsheng Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Key Laboratory of Advanced Forging and Stamping Technology and Science of Ministry of National Education Yanshan University Library Yanshan University

The two-rotational-degrees-of-freedom（2R） parallel mechanism（PM） with two continuous rotational axes（CRAs） has a simple kinematic *** is therefore easy to implement trajectory planning,parameter calibration,and motion control,which allows for a variety of application ***,no systematic analysis on structural constraints of the 2R-PM with two CRAs has been performed,and there are only a few types of 2R-PM with two ***,a theory regarding the type synthesis of the 2R-PM with two CRAs is systematically ***,combining the theories of reciprocal screw and space geometry,the spatial arrangement relationships of the constraint forces applied to the moving platform by the branches are explored,which give the 2R-PM two *** different distributions of the constraint forces in each branch are also *** the basis of the obtained structural constraints of branches,and considering the geometric relationships of constraint forces in each branch,the appropriate kinematic chains are *** the reasonable configuration of branch kinematic chains corresponding to every structural constraint,a series of new 2R-PMs with two CRAs are finally obtained.

关键词： type synthesis continuous rotational axes two rotational degrees of freedom parallel mechanism constraint force

Over-constraint and a Unified Mobility Method for General Spatial Mechanisms Part 1: Essential Principle

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Chinese Journal of Mechanical Engineering 2015年第5期28卷 869-877页

作者： ZENG Daxing LU Wenjuan HUANG Zhen School of Mechanical Engineering Yanshan University

Compared with the parallel mechanisms, the mobility analysis of the general multi-loop spatial mechanisms（GMSMs） is more difficult to obtain correct results. The reason is that its multi-loop is formed through several times of closings and there also exists motion coupling even strong coupling, where the over-constraints are concealed. However, the mobility analysis for this kind of mechanisms has been paid few attentions. A new systemic methodology for analyzing mobility is proposed for GMSMs also based on the screw theory. The key issue for mobility analysis is to recognize the over-constraint. Firstly, three theorems are given and point out： the reason and site of over-constraint occurrence, calculating the number of over-constraints by the screw theory, and how to analyze the over-constraints for a single-loop mechanism as well. Then, three closing forms for GMSMs are proposed including rigid closure, movable closure and dynamic closure, and for the three different forms the different analysis methods are also given. Especially, for the most difficult issue of GMSMs with the multi-loop Closure in many times and the inevitable motion coupling, two important methods are proposed：＂recognizing over-constraints by analyzing relative movement＂ and ＂recognizing over-constraints by virtual loop＂. The two methods are well used to solve the issue. Above-mentioned principles are not only systematic and effective but also unified. They provide a theoretical basis for the general multi-loop spatial mechanisms.

关键词： mobility analysis multi-loop over-constraint closing forms virtual loop

Improved electrochemical kinetic performances of La-Mg-Ni-based hydrogen storage alloys with lanthanum partially substituted by yttrium

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Journal of Rare Earths 2015年第4期33卷 397-402页

作者：刘治平杨淑琴李媛马明臻韩树民 State Key Laboratory of Metastable Materials Science and Technology Yanshan University College of Environmental and Chemical Engineering Yanshan University

Yttrium （Y） has been used as the partial substitution element for lanthanum （La） to improve the electrochemical kinetic performances of La-Mg-Ni-based hydrogen storage alloys. Lao.80-xYxMg0.20Ni2.85Mn0.10Coo.55Al0.10 （x=0.00, 0.05 and 0.10） alloys were prepared by the inductive melting technique. The alloys were composed of LaNi5 and （La,Mg）2Ni7 phases, the introduction of Y promoted the formation of （La,Mg）2Ni7 phase, and thus the Y-substituted alloy electrodes exhibited higher discharge capacities. Y substitution was also found to be effective to improve the discharge kinetics of the alloy electrodes. When the Y content x increased from 0.00 to 0.10, the high-rate dischargeability of the alloy electrodes at a discharge current density of 1800 mA/g （HRDl800） in- creased from 23.6% to 39.7% at room temperature. In addition, the measured HRD1800 showed a linear dependence on both the ex- change current density and the hydrogen diffusion coefficient at different temperatures, respectively.

关键词： La-Mg-Ni-based alloys Y substitution phase composition electrochemical kinetics rare earths

Preparation of nanometer oxides La_(1-x)Sr_xMnO_3 by absolute alcohol as solvent

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中国有色金属学会会刊：英文版 2008年第2期18卷 351-355页

作者：胡婕邵光杰郭鹏秦秀娟邢广忠 Department of Environment and Chemistry Yanshan University State Key Laboratory of Metastable Materials Science and Technology Yanshan University

Nanometer oxides La1-xSrxMnO3 were synthesized by absolute alcohol as *** desired metal cations were chelated in a solution using citric acid as the chelating *** order to get the optimum preparation condition for La1-xSrxMnO3,the pH of primal commix solution,the molar fraction of citric acid and baking temperature of predecessor block were researched by orthogonal test design method with different *** thermal decomposition of the metal carboxylate precursor gels was studied by TG/DTA and the products derived from calcinations of the gels were characterized by XRD and *** polarization curves were acquired on an electrochemical work station(LK98)and the discharge curves were acquired on a testing instrument of batteries(DC-5)with a constant current discharge under 120 mA/*** results reveal that the nanometer oxides can be achieved by absolute alcohol as solvent and it has better catalytic activity.

关键词：氧化物镧无水酒精溶剂阳离子

Automatic generation of min-weighted persistent formations

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Chinese Physics B 2009年第8期18卷 3104-3114页

作者：罗小元李绍宝关新平 Department of Electrical Engineering Yanshan University

This paper researched into some methods for generating min-weighted rigid graphs and min-weighted persistent graphs. Rigidity and persistence are currently used in various studies on coordination and control of autonomous multi-agent formations. To minimize the communication complexity of formations and reduce energy consumption, this paper introduces the rigidity matrix and presents three algorithms for generating rain-weighted rigid and min- weighted persistent graphs. First, the existence of a min-weighted rigid graph is proved by using the rigidity matrix, and algorithm 1 is presented to generate the min-weighted rigid graphs. Second, the algorithm 2 based on the rigidity matrix is presented to direct the edges of min-weighted rigid graphs to generate min-weighted persistent graphs. Third, the formations with range constraints are considered, and algorithm 3 is presented to find whether a framework can form a min-weighted persistent formation. Finally, some simulations are given to show the efficiency of our research.

关键词： min-weighted persistent graph rigidity matrix minimally rigid graph formation multi-agent

Corrosion resistance,composition and structure of RE chemical conversion coating on magnesium alloy

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中国有色金属学会会刊：英文版 2008年第A1期18卷 349-353页

作者：于升学曹靖瑜陈玲韩婧张瑞军 State Key Laboratory of Metastable Materials Science and Technology Yanshan University Department of Applied Chemistry Yanshan University

Golden yellow rare earths chemical conversion coating was obtained on the surface of magnesium alloy by immersing in cerium sulfate *** corrosion resistance of RE conversion coating was evaluated using inmersion test and potentiodynamic polarization measurements in 3.5%NaCl *** morphologies of samples before corrosion and after corrosion were observed by *** structures and compositions of the RE conversion coating were studied by means of XPS,XRD and *** results show that,the conversion coating consists of mainly two kinds of element Ce and O,the valences of cerium are +3 and +4,and OH exists in the *** anti-corrosion property of magnesium alloy is increased obviously by rare earths conversion coating,Its self-corrosion current density decreases and the coating has self-repairing capability in the corrosion process in 3.5%NaCl solution.

关键词：镁合金化学转化处理金属处理热处理

Roles of pre-formed martensite in below-Ms bainite formation,microstructure,strain partitioning and impact absorption energies of low-carbon bainitic steel

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Journal of Materials Science & Technology 2022年第1期96卷 69-84页

作者： Lihe Qian Zhi Li Tongliang Wang Dongdong Li Fucheng Zhang Jiangying Meng State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan UniversityQinhuangdao 066004China Library of yanshan university Yanshan UniversityQinhuangdao 066004China

The roles of pre-formed martensite(PM)in below-Ms bainite formation,microstructure,crystallography,strain partitioning and mechanical properties of a low-carbon bainitic steel were investigated using electron-backscattered diffraction,transmission electron microscopy,micro digital image correlation technique and mechanical *** is demonstrated that the pre-formation of martensite eliminates the incubation time for bainite transformation at various austempering temperatures below Ms,indicative of its acceleration effect at the early stage of *** effect is mainly attributed to the surfaces or tips of the PM acting as the nuclei of subsequently-formed bainite,with initial bainite tending to form around the ***,the finishing time for below-Ms bainite transformation,especially at even lower temperatures,is retarded,owing to the dividing effect of PM on parent austenite grains,the decreasing effect of lowered isothermal temperature on the diffusion rate of carbon atoms and the strengthening effect of lowered isothermal temperature on supercooled *** and its adjacent bainitic laths have nearly the same crystallographic orientation and belong to the same *** pre-formation of martensite largely refines the bainitic blocks/laths and retained *** specimens with PM show relatively uniform strain partitioning among various phases,contrasting with the specimens without PM,for which strains are highly concentrated in the bainite region nearby fresh martensite/austenite(M/A)blocks or between adjacent M/A *** impact absorption energies of the specimens with PM,when austempered at 30-60℃ below Ms,are more than twice higher than those of the specimens without PM,at no expense of tensile properties.

关键词： Bainite Martensite Impact toughness Transformation kinetics Strain partitioning