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Effects of Ca substitution and surface treatment on electrochemical performances of Ml_(1.0-x) Ca_xNi_(4.0) Co_(0.6) Al_(0.4) hydrogen storage alloy electrodes

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中国有色金属学会会刊：英文版 1999年第3期9卷 487-492页

作者： Chen Weixiang(陈卫祥) 1, Qi Jianqin(祁建琴) 1, Chen Changpin(陈长聘) 2.1. department of physics 2. department of Materials Science and Engineering, Zhejiang university, Hangzhou 31002., P. R. China 浙江大学物理系浙江杭州浙江大学材料科学与工程系浙江杭州

The influences of Ca substitution for Ml and surface treatment on electrochemical performances of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 hydrogen storage alloy electrode were investigated. Ca substitution with x 2.for Ml could improve its discharge capacity, but Ca substitution with x >0.2.could decrease the capacity. It was also found that Ca substitution deteriorates the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode. In order to improve these properties of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 alloy electrode, the alloy was treated in 6 mol/L KOH+0.02.mol/L KBH 4 solution. The results showed that the surface treatment improves the electrochemical performances such as the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode. :The influences of Ca substitution for Ml and surface treatment on electrochemical performances of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 hydrogen storage alloy electrode were investigated. Ca substitution with x 2.for Ml could improve its discharge capacity, but Ca substitution with x >0.2.could decrease the capacity. It was also found that Ca substitution deteriorates the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode. In order to improve these properties of Ml 1.0- x Ca x Ni 4.0 Co 0.6 Al 0.4 alloy electrode, the alloy was treated in 6 mol/L KOH+0.02.mol/L KBH 4 solution. The results showed that the surface treatment improves the electrochemical performances such as the electrocatalytic activity, high rate dischargeability and cycling durability of the alloy electrode.

关键词： hydrogen storage alloy electrode Ca substitution surface modification

Study on the two and three-parameter working stability regions of 3Y-TZP suspension

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Science China(Technological Sciences) 2006年第5期49卷 547-568页

作者： CHEN Youqiang1, 2. ZHANG Xinni3, CHEN Sha’ou3 & QI Ping3 1. department of Chemistry, Qingdao university, Qingdao 2.6071, China 2. department of Chemistry, Tsinghua university, Beijing 100084, China 3. department of physics, Qingdao university, Qingdao 2.6071, China department of Chemistry Qingdao University Qingdao China department of Chemistry Tsinghua University Beijing China department of physics Qingdao University Qingdao China

We determined the variation tendency of viscosity (η) at various solids load- ing (α) for 3Y-TZP suspension as a function of dispersant concentration (Cw) using vis- cosity measurement, measured the diameter of particles as a function of Cw in very dilute suspension using light scattering method, and obtained the surface features of the sedi- ment of suspension with different Cw using SEM. We also discussed the influence of the microstructure of adsorbed polymer layers on particles and their interactions in the dis- persing medium on the stability of suspension. Then two different stable states and two different unstable states for 3Y-TZP suspension were given. Accordingly, the (Cw, η), (Cw, α), and (α, η) two-parameter, and (Cw, α, η) three-parameter stability maps were con- structed. Based on the DLVO theory calculations, the dispersant concentration, particle distance (r), and interparticle potential energy (VT) maps with various solids loading for 3Y-TZP aqueous suspension were also constructed. In (Cw, r) two-parameter coordinate system, the stable motion region map for particles was established. The Cw, α, and VT,max (the highest potential energy) surface of the potential barrier map was obtained through calculation and simulation on the basis of the surfaces of Cw, r, VT maps introduced above. The (Cw, α) two-parameter stability map was then obtained from the Cw, α, VT,max map. The results showed that this theoretical map can qualitatively prove the experimentally obtained results—the existence of different dispersed states of particles in suspension system and the variation tendency of suspension stability with changing each parame- ter—were reasonable.

关键词： 3Y-TZP, suspension, stability, DLVO theory, interparticle potential energy.

The kink-soliton and antikink-soliton in quasi-one-dimensional nonlinear monoatomic lattice

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Science China(physics,Mechanics & Astronomy) 2005年第2期48卷 150-157页

作者： XU Quan1 & TIAN Qiang2.1. Scientific and Technological Office, Daqing Teacher College, Daqing 163712. China 2. department of physics , Beijing Normal university, Beijing 100875, China Scientific and Technological Office Daqing Teacher College Daqing China department of physics Beijing Normal University Beijing China

The quasi-one-dimensional nonlinear monoatomic lattice is analyzed. The kink-soliton and antikink-soliton are presented. When the interaction of the lattice is strong in the x-direction and weak in the y-direction, the two-dimensional (2.) lattice changes to a quasi-one-dimensional lattice. Taking nearest-neighbor interaction into account, the vibration equation can be transformed into the KPI, KPII and MKP equation. Considering the cubic nonlinear potential of the vibration in the lattice, the kink-soliton solution is presented. Considering the quartic nonlinear potential and the cubic interaction potential, the kink-soliton and antikink-soliton solutions are presented.

关键词： two-dimensional nonlinear lattice, quasi-one-dimensional nonlinear lattice, kink-soliton, antikink-soliton.

Existence of the solutions and the attractors for the large-scale atmospheric equations

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Science China Earth Sciences 2006年第6期49卷 650-660页

作者： HUANG Haiyang1 & GUO Boling2.1. department of Mathematics, Beijing Normal university, Beijing 100875, China 2. Institute of Applied{2. and Computational Mathematics, Beijing 100080, China department of Mathematics Beijing Normal University Beijing China Institute of Applied physics and Computational Mathematics Beijing China

In this paper, firstly, the proper function space is chosen, and the proper expression of the operators is introduced such that the complex large-scale atmospheric motion equations can be described by a simple and abstract equation, by which the definition of the weak solution of the atmospheric equations is made. Secondly, the existence of the weak solution for the atmospheric equations and the steady state equations is proved by using the Galerkin method. The existence of the non-empty global attractors for the atmospheric equations in the sense of the Chepyzhov-Vishik’s definition is obtained by constructing a trajectory attractor set of the atmospheric motion equations. The result obtained here is the foundation for studying the topological structure and the dynamical behavior of the atmosphere attractors. Moreover, the methods used here are also valid for studying the other atmospheric motion models.

关键词： atmosphere equations, weak solution, trajectory attractor, global attractor, equilibrium.

Mathematical stencil and its application in finite difference approximation to the Poisson equation

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Science China Mathematics 2005年第10期48卷 1421-1429页

作者： FENG Hui~1 ZHANG Baolin~(1,2. & LIU Yang~1 1. department of Mathematics,Wuhan university,Wuhan 430072.China 2. Laboratory of Computational{2.,Institute of Applied{2. and Computational Mathematics,Beijing 100088. China department of Mathematics Wuhan University Wuhan China Laboratory of Computational physics Institute of Applied Physics and Computational Mathematics Beijing China

The concept of mathematical stencil and the strategy of stencil elimination for solving the finite difference equation is presented, and then a new type of the iteration algorithm is established for the Poisson equation. The new algorithm has not only the obvious property of parallelism, but also faster convergence rate than that of the classical Jacobi iteration. Numerical experiments show that the time for the new algorithm is less than that of Jacobi and Gauss-Seidel methods to obtain the same precision, and the computational velocity increases obviously when the new iterative method, instead of Jacobi method, is applied to polish operation in multi-grid method, furthermore, the polynomial acceleration method is still applicable to the new iterative method.

关键词： mathematical stencil, stencil elimination, Poisson equation, finite difference, iterative algorithm,parallelism.

Two-dimensional simulation of Poiseuille-Rayleigh-Bénard flows in binary fluids with Soret effect

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Progress in Natural Science:Materials International 2007年第12期17卷 1389-1396页

作者： Hu Jun1 and Yin Xieyuan2.1. Institute of Applied physics and Computational Mathematics, Beijing 100088, China 2. department of Modern Mechanics,{2. of Science and Technology of China, Hefei 2.002., China) Institute of Applied physics and Computational Mathematics Beijing 100088 China department of Modern Mechanics University of Science and Technology of China Hefei 230027 China

Poiseuille-Rayleigh-Bénard flows in binary fluids with Soret effect are directly simulated by a mixed finite element method. A temperature perturbation is used as an initial disturbed source for the basic parallel flows. The whole spatio-temporal evolution of the binary fluid flows is exhibited: initially only the disturbed mode with the wavenumber k=π is amplified while others are damped, and continuously the amplified mode grows further and the nonlinear effect becomes important; after a nonlinear evolution transition the flow system evolves finally into a periodic right traveling wave.

关键词： Poiseuille-Rayleigh-Bénard flow Soret effect through-flow.

Topological chirality and achirality of the closed circular DNAs

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Chinese Science Bulletin 1997年第20期42卷 1705-1708页

作者： QIU Wenyuan and XIN Houwen1. department of Chemical physics,{2. of Science and Technology of China, Hefei 2.002., China 2. department of Chemistry, Lanzhou{2., Lanzhou 730000, China department of Chemical physics University of Science and Technology of China Hefei China department of Chemistry Lanzhou University I anzhou China

THE study of the relations between the topological structure and its function is one of the focus-es in modern chemistry and life science. In this note we set up a topological model to de-scribe the ccDNAs on the basis of Seifert construction in knot theory. Our model for theccDNAs helps to determine whether a structure is topologically chiral or achiral. This is one ofthe fundamental biological problems.

关键词： DNA topology knot theory topologiesl chirality topological achirality.

I-V and C-V properties of TiO_2.thin film by pulsed-laser reactive deposition

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Chinese Science Bulletin 1998年第16期43卷 1344-1349页

作者： FU Zhengwen 1, ZHOU Mingfei 1, ZHANG Shengkun 2.CHEN Lianyao 2.and QIN Qizong 1 1. Laser Chemistry Institute, Fudan university, Shanghai 2.0433, China 2. department of physics, Fudan university, Shanghai 2.0433, China Laser Chemistry Institute Fudan University Shanghai China department of Pnysics Fudan University Shanghai China

TiO-2.thin films have bee deposited on p-Si(111) substrates by pulsed-laser ablation of metallic Ti target in the O-3 ambient. The current-voltage and capacitance-voltage of the Al/TiO-2.Si capacitors are measured. The results show that the dielectric constant of thin film after being annealed at 700℃ is found to be 46, and the border trap density and the interface state density at the TiO-2.p-Si interface are 1.8×10 12.cm -2.and 2.10 12.eV -1·cm -2. respectively. The conduction mechanisms of as-deposited films are also discussed.

关键词： TiO-2 dielectric properties electrical properties pulsed-laser deposition.

Molecular dynamics simulation of thermal stability of nanocrystalline vanadium

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Science China(Technological Sciences) 2006年第4期49卷 400-407页

作者： WEI Mingzhi1, XIAO Shifang1, YUAN Xiaojian2.& HU Wangyu1,2.1. Material Science and Engineering College, Hunan university, Changsha 410082. China 2. department of Applied{2., Hunan university, Changsha 410082. China Material Science and Engineering College Hunan University Changsha China department of Applied physics Hunan University Changsha China

The microstructure and thermal stability of nanocrystalline vanadium with an average grain size ranging from 2.86 to 7.50 nm are calculated by means of the analytic embedded-atom method and molecular dynamics. The grain boundary and nanocrystal- line grain atoms are differentiated by the common neighbor analysis method. The results indicate that the fraction of grain boundary increases with the grain size decreasing, and the mean energy of atoms is higher than that of coarse crystals. The thermal-stable tem- peratures of nanocrystalline vanadium are determined from the evolution of atomic energy, fraction of grain boundary and radial distribution function. It is shown that the stable tem- perature decreases obviously with the grain size decreasing. In addition the reasons which cause the grain growth of nanocrystalline vanadium are discussed.

关键词： nanocrystalline, embedded-atom method, molecular dynamics, thermal stability.