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Ab initio molecular dynamics simulation of the atom packing and density of Al-Ni amorphous alloys

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Science china(Technological Sciences) 2010年第12期53卷 3175-3182页

作者： YU ChunYan1, HUI XiDong1, CHEN XiaoHua1, LIU XingJun1, LIN DeYe1, LIU ZiKui2.& CHEN GuoLiang1 1 state Key Laboratory for Advanced Metals and Materials, University of Science and Technology beijing, beijing 100083, china 2.Department of Materials Science and Engineering, Pennsylvania state University, University Park, PA 16802. USA 1. state Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China2. Department of Materials Science and Engineering Pennsylvania State University University Park PA 16802 USA

Al-Ni alloys have better glass forming ability (GFA) than other Al-based alloys. However, the relationship among the atomic arrangement, glass transition, packing density and composition hasn’t been systematically studied. In this paper the ab initio molecular dynamics simulation (AIMD) was performed on the atom packing and density of AlxNi100-x (x=80, 83, 85, 86, 87 and 90) alloys. The pair correlation function and Voronoi tessellation indicated that there are obvious topological and chemical short-range orders in these alloys. The topological structure consists of Al-centered icosahedra like and Ni-centered tri-capped trigonal prism (TTP) like polyhedra. There is strong chemical short-range ordering between Al and Ni atoms indicated by the bond-length of Al-Ni pair shorter than the sum of the radii of Al and Ni atoms, which increases with the increasing of Ni content. It is shown that the densities of amorphous alloys don’t agree with the linear law with a peak at x=85. Based on the features of the structure and density, it is concluded that Al-Ni alloys at x=84–86 have high GFA, which can be extended to multi-component Al-based alloys.

关键词： AIMD Al-Ni alloys density short-range order chemical short-range order

Quantum statistical entropy corresponding to cosmic horizon in five-dimensional spacetime

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Science china(Physics,Mechanics & Astronomy) 2008年第2期51卷 140-146页

作者： ZHAO Ren1,2.& ZHANG ShengLi1 1 Department of Applied Physics, Xi’an Jiaotong University, Xi’an 710049, china 2.Department of Physics, Shanxi Datong University, Datong 037009, china Department of Applied Physics Xi’an Jiaotong University Xi’an 710049 China Department of Physics Shanxi Datong University Datong 037009 China

The generalized uncertainty relation is introduced to calculate the quantum statis-tical entropy corresponding to cosmic horizon. By using the new equation of state density motivated by the generalized uncertainty relation, we discuss entropies of Bose field and Fermi field on the background of five-dimensional spacetime. In our calculation, we need not introduce cutoff. There is no divergent logarithmic term in the original brick-wall method. And it is obtained that the quantum statistical en-tropy corresponding to cosmic horizon is proportional to the area of the horizon. Further it is shown that the entropy corresponding to cosmic horizon is the entropy of quantum state on the surface of horizon. The black hole's entropy is the intrinsic property of the black hole. The entropy is a quantum effect. In our calculation, by using the quantum statistical method, we obtain the partition {2. of Bose field and Fermi field on the background of five-dimensional spacetime. We provide a way to study the quantum statistical entropy corresponding to cosmic horizon in the higher-dimensional spacetime.

关键词： quantum statistical entropy generalized uncertainty relation high-dimensional spacetime

A new grid-associated algorithm in the distributed hydrological model simulations

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Science china(Technological Sciences) 2010年第1期53卷 235-241页

作者： XU Rui1,2.HUANG XiaoXue1,LUO Lin1 & LI ShaoCai3 1 state Key Laboratory of Hydraulics and Mountain River Engineering College of Architecture and environment,Sichuan University,Chengdu 610065,{2. 2.College of Electronic Engineering,Guilin University of Electronic Technology,Guilin 541004,{2. 3 College of Life Sciences,Sichuan University,Chengdu 610065,{2. 1. state Key Laboratory of Hydraulics and Mountain River Engineering College of Architecture and environment Sichuan University Chengdu 610065 China2. College of Electronic Engineering Guilin University of Electronic Technology Guilin 541004 China3. College of Life Sciences Sichuan University Chengdu 610065 China

This paper presents a new grid-associated algorithm to improve the performance of a D8 algorithm based distributed hydrological model *** algorithm is based on the well known single-flow D8 algorithm of grid *** algorithm allocates calculation priorities according to the distance between the units and the outlet,then carries out the ergodic computations of the hydrological units according to the priority *** the parallelized algorithm,a standard thread-level shared memory system for parallel programming(OpenMP-Open specifications for Multi processing) was introduced,and the parallel coding was implemented in C lan-guage.A case study showed that the absolute speed-up ratio of the grid-associated algorithm is 1.64 over the original D8 algorithm,and the linear speed-up ratio of the parallel associated algorithm is 2.42.under 4 *** parallel grid-associated algorithm can be applied to a variety of research fields that use the grid method.

关键词： distributed hydrological model grid-association algorithm OpenMP parallel computing

Electronic Structures and Bonding Properties of Ti_2.lC and Ti_3AlC_2

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Journal of Wuhan University of Technology(Materials Science) 2007年第1期22卷 27-30页

作者：闵新民 Department of Applied Chemistry School of Science Wuhan University of Technology state Key Laboratory of Advanced Technology for Materials Synthesis and processing Wuhan University of Technology Wuhan 430070 China

The relation among electronic structure, chemical bond and property of Ti2.lC, Ti3AlC2.and doping Si into Ti2.lC was studied by density function and the discrete variation （DFT-DVM） method. After adding Si into Ti2.lC, the interaction between Si and Ti is weaker than that between Al and Ti, and the strengths of ionic and covalent bonds decrease both. The ionic and covalent bonds in Ti3AlC2. especially in Ti-Al, are stronger than those in Ti2.lC. Therefore, in synthesis of Ti2.lC, the addition of Si enhances the Ti3AlC2.content instead of Ti2.lC. The density of state （DOS） shows that there is mixed conductor characteristic in Ti2.lC and Ti3AlC2. The DOS of Ti3AlC2.is much like that of Ti2.lC. Ti2.iAl1-xC has more obvious tendency to form a semiconductor than Ti2.lC, which is seen from the obvious difference of partial DOS between Si and Al 3/7.

关键词： Ti2.lC Ti3SiC2 doping electronic structure chemical bond

Neural integrated control for a free-floating space robot with suddenly changing parameters

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Science china(Information Sciences) 2011年第10期54卷 2091-2099页

作者： ZHANG WenHui 1,2.,QI NaiMing 2.MA Jing 1,3 & XIAO AYang 2.1 School of Electromechanical Engineering,Xuzhou Normal University,Xuzhou 2.1116,china 2.School of Aerospace,Harbin Institute of Technology,Harbin 150001,china 3 Department of Engineering,Northeast Agricultural University,Harbin 150001,china 1. School of Electromechanical Engineering Xuzhou Normal University Xuzhou 221116 China2. School of Aerospace Harbin Institute of Technology Harbin 150001 China3. Department of Engineering Northeast Agricultural University Harbin 150001 China

Because the state of a free-floating space robot model is uncertain and sudden changes in the model parameters might undermine the stability of the system,this paper proposes a control strategy based on a variable structure neural integrated *** scheme does not need a precise space robot model,making use of the radial basis function neural network ability approach to learn about an uncertain *** network weights are adjusted online in *** the early period of the control phase and parameter changes,the variable structure controller compensates for the uncertain model which the neural network could not learn *** also creates global asymptotic stability for the whole closed-loop *** results show that the controller can handle bad changeable conditions and has important application value for defense,aerospace and other major security fields.

关键词： neural network variable structure adaptive control global asymptotical stability

Modified methods of designing sliding surface in variable structure systems

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Journal of Harbin Institute of Technology(New Series) 1999年第4期6卷 1-6页

作者： FENG Yong 1, AN Cheng quan 1, LI Tao 2.(1. Dept. of Electrical Engineering, Harbin Institute of Technology, Harbin 150001, china 2. Dept. of Automation, Tsinghua University, beijing 100084, china)

This paper presents two modified methods of designing sliding surface in variable structure systems based on the mathematical equation established for the relationship between the steady state error of the system and the slope of the sliding surface. Replacing the switching function with the saturation function in the control signal, the methods can not only reduce the system steady state error, but also smooth chatterring in the variable structure systems.

关键词： variable structure systems (VSS) nonlinear systems sliding mode

About the convergence rates of a class of gene expression programming

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Science china(Information Sciences) 2010年第4期53卷 715-728页

作者： DU Xin1,2. & DING LiXin1 1state Key Laboratory of Software Engineering, Wuhan University, Wuhan 430072. china 2.epartment of Information Engineering, Shijiazhuang University of {2.nomics, Shijiazhuang 050031, china 1. state Key Laboratory of Software Engineering Wuhan University Wuhan 430072 China2. Department of Information Engineering Shijiazhuang University of Economics Shijiazhuang 050031 China

This paper studies the convergence rates of gene expression programming based on maintaining elitist (ME-GEP) by means of Markov chain and spectrum analysis. We obtain the following results: (1) ME-GEP algorithm converges to the global optimum in probability. (2. The convergence rates of ME-GEP algorithm depend on the revised spectral radius of transition matrix of Markov chain corresponding to the algorithm. (3) The upper bounds of revised spectral radius are estimated, which are determined by the parameters of ME-GEP algorithm. (4) As an application of the theoretical results acquired in the paper, the convergence rates of ME-GEP for the polynomial function modeling problem are also analyzed, which verifies the relations between the convergence rates and the algorithm parameters.

关键词： GEP ME-GEP convergence rates Markov chain revised spectral radius

Study on blister of the coating on solid cantilevers of hydraulic supports for coal mining

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Science china(Technological Sciences) 2010年第12期53卷 3183-3188页

作者： MENG GuoZhe1, FU JinLiang2. SUN FeiLong1, SHAO YaWei1, ZHANG Tao1 & WANG FuHui1, 3 1 Corrosion and protection Laboratory, Key Laboratory of Superlight Materials and Surface Technology (Harbin Engineering University), Ministry of Education, Harbin 150001, china 2.Technology Center of Zhengzhou Coal Mining Machinery Group Co. Ltd., Zhengzhou 100049, china 3 state Key Laboratory for Corrosion and protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, china 1. Corrosion and protection Laboratory Key Laboratory of Superlight Materials and Surface Technology (Harbin Engineering University) Ministry of Education Harbin 150001 China2. Technology Center of Zhengzhou Coal Mining Machinery Group Co. Ltd. Zhengzhou 100049 China3. State Key Laboratory for Corrosion and Protection Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

In this work, blister of the Cu-Sn plus Cr coating on solid cantilevers of hydraulic supports for coal mining was investigated by hydrogen-charging, Devanathan-Stachurski method and electrochemical impedance spectroscopy (EIS) measurement. It was found that the permeation hydrogen during the pickling process and the electroplating process was responsible for the blisters. The residual tensile stress due to the machining process would increase the permeation hydrogen amount during pickling and electroplating processes.

关键词： hydrogen blister hydrogen permeation EIS sub-surface hydrogen concentration

Research on Water Resources Conservation of Mountain River Based on the Concept of Region Partition

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Journal of Mountain Science 2011年第4期8卷 582-591页

作者： LIU Yubang TAO Qingyu LIANG Chuan WU Yong state Key Laboratory of Geohazard Prevention and Geoenvironment {2. Chengdu University of Technology Chengdu 61o059 China state Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resource & Hydropower Sichuan University Chengdu 61oo65 China Academic Journal Center of Chengdu University of Technology Chengdu 61oo59 China

Presently concepts and methods related to water resources conservation of mountain rivers are seriously insufficient,and its level is far from being adaptable to the development of a harmonious *** mountain ecosystems play a key role in water resources conservation of mountain rivers,and the characteristics of mountain ecosystems and hydrologic features of mountain river follow strong temporal and spatial distribution,partition theory can be applied to the water resources conservation of mountain *** theory observes the following partition principles:{2. relativity,spatial continuity,integralcounty,meeting management needs,hierarchical principle,and comparability *** it lays equal emphasis on both water resources conservation and environmental protection,on both water quality conservation and water quantity protection,on the combination of water features,water cycle and water *** the partition methods,index method and map superposition method will be applied in region *** example of region partition of water resources conservation in the upper reaches of the Yangtze River shows that the partition theory is practicable in water resources conservation of mountain rivers,and it provides a platform for future study in water resources conservation.

关键词： Water resources conservation Mountain river Region partition Mountain ecosystems