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A computer simulation of nucleation and growth of thin films

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Science china(Physics,Mechanics & Astronomy) 2004年第4期47卷 442-451页

作者： ZHENG Xiaoping1,ZHANG Peifeng2.HE Deyan2.LIU Jun2. MA Jiantai3 1. Key Laboratory of Opto-Electronic Technology and Intelligent Control, Ministry of Education, lanzhou Jiaotong University, lanzhou 73.070,{2. 2. School of Physical Science and Technology, lanzhou University, lanzhou 730000,{2. 3. School of Chemistry and Chemistry Engineering, lanzhou University, lanzhou 730000,{2. 1. Key Laboratory of Opto-Electronic Technology and Intelligent Control Ministry of Education Lanzhou Jiaotong University 730070 Lanzhou China 2. School of Physical Science and Technology Lanzhou University 730000 Lanzhou China 3. School of Chemistry and Chemistry Engineering Lanzhou University 730000 Lanzhou China

A three-dimensional kinetic Monte Carlo technique has been developed for simulating the nucleation and growth of thin films. This model involves incident atom attachment, surface diffusion of the atoms on the growing surface and atom detachment from the growing surface. It takes some new effects into account, such as a significant improvement in calculation of activation energy for the atom diffusion, which renders the model more reasonable. In addition three optimum temperatures and the consistency of their dependence on deposition rate have been found out; the dependence of the surface roughness and relative density on the deposition rate has been discussed; and the approximation of freezing neighbour atoms and periodic boundary conditions has been applied.

关键词： Monte Carlo, thin film, nucleation, surface roughness, relative density.

Rhodium catalyzed asymmetric Pauson-Khand reaction using SDP ligands

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Science china Chemistry 2006年第1期49卷 81-87页

作者： FAN Baomin1, LI Shen2. XIE Jianhua2. WANG, Lixin2. TU Yongqiang1 & ZHOU Qilin2.1. State Key Laboratory of applied Organic Chemistry,lanzhou University,lanzhou 730000,china 2. State Key Laboratory of Elemento-organic Chemistry,Nankai University,Tianjin 300071, china 1. State Key Laboratory of applied Organic Chemistry Lanzhou University Lanzhou 730000 China 2. State Key Laboratory of Elemento-organic Chemistry Nankai University Tianjin 300071 China

The activity and enantiocontrol ability of the chiral catalysts prepared from spiro di-phosphine ligands, SDP, and rhodium precursor were investigated in the asymmetric catalytic Pau-son-Khand reaction. The results showed that SDP ligands were very effective in Rh-catalyzed Pau-son-Khand reaction, and their complexes with rhodium could convert a variety of 1,6-enyne compounds into bicyclopentone derivatives under CO atmosphere in high yields with good enantioselec-tivities. The SbF6- was found to be a suitable counter anion of the catalyst, and 1,2.dichloroethane was the best choice of the solvent for Pauson-Khand reaction.

关键词： Pauson-Khand reaction, asymmetric catalysis, diphosphine ligand, rhodium.

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 {2. Physics and Computational mathematics, Beijing 100080, china 1. Department of mathematics Beijing Normal University Beijing 100875 China 2. Institute of applied Physics and Computational mathematics Beijing 100080 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.

On some tests-based projection pursuit for elliptical symmetry of a high-dimensional distribution

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Chinese Science Bulletin 1998年第6期43卷 450-458页

作者： JING Ping 1 and ZHU Lixing 2.1. mathematics Lab, china University of Mining & Technology, Beijing 100083, china 2. Probability Lab, Institute of applied mathematics, Chinese Academy of Sciences, Beijing 100080, china mathematics Lab China University of Mining & Technology Beijing China Probability Lab Institute of Applied Mathematics Chinese Academy of Sciences Beijing China

Some test statistics of Kolmogorov type and Cramér-von Mises type based on projection pursuit technique are proposed for the testing problem of sphericity of a high-dimensional distribution. The limiting distributions of the test statistics are derived under the null hypothesis and under any fixed alternative. The asymptotic properties of bootstrap approximation are investigated. Furthermore, for computational reasons, an approximation for the statistics, based on the number theoretic method, is suggested.

关键词： bootstrap approximation projection pursuit type statistic elliptical symmetry.

Static mechanics analysis of no bumping or vibration welding structure applied in high-speed & heavy-load CWR with single inclined surface

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Science china(Technological Sciences) 2010年第12期53卷 3153-3160页

作者： SONG YuQuan1, LUO WuWei2.& TAO Yi2.1 Jilin University, Changchun 13002., china 2.Shenyang railway Bureau, Shenyang 110013, china 1. Jilin University Changchun 130022 China2. Shenyang Railway Bureau Shenyang 110013 China

Nowadays, the sleeper, railroad bed, welding technology and materials of the high-speed & heavy-load Continuous Welded Rail (CWR) have been improved greatly. However, the orientation relationship between welding surface and rail is still orientation structure, which appeared 185 years ago in UK, namely, the welding surface is normal to the longitudinal direction of the rail. Thus rail welds are subject to vertical pure shear stress, lateral pure shear stress and axial pure tensile stress. Pure shear stress and pure tensile stress are both dangerous stresses, which result in failure of welds under high-speed & heavy-load condition for a long time. When the wheels pass rail welds, it is difficult to avoid vertical bumping and lateral vibration. In order to solve these problems, in this paper we put forward the single inclined welding surface having dip angle α with the lateral rail or dip angle β with the vertical rail and analyze the position geometry and stress state. Thus the vertical bumping and lateral vibration are basically eliminated, then the bearing capacity of the welding surface is significantly improved, and the stress of axial pure tensile and lateral pure shear of the welding surface is reduced.

关键词： continuous welded rail single inclined welding surface bearing capacity stress state regularity

Two-dimensional Riemann problems of simplified Euler equation

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Chinese Science Bulletin 1998年第6期43卷 441-444页

作者： YANG Xiaozhou 1,2.and HUANG Feimin+1 1. Institute of applied mathematics, Chinese Academy of Sciences, Beijing 100080,{2. 2. Department of mathematics, Shantou University, Guangdong 515063,{2. Institute of applied mathematics Chinese Academy of Sciences Beijing China Department of mathematics Shantou University Guangdong China

The two-dimensional Riemann problem of simplifed Euler equation is discussed, in which initial value contains two different constant states that are separated by a smooth curve. This problem is a natural description of realistic phenomena, but it is hard to study by conventional idea. So a new approach is proposed. Some new properties about two-dimensional rarefaction wave, shock wave and intermediate state of solutions are disclosed.

关键词： D Riemann problem implicit functions cylindrical surface pencil of cylindrical surface.

Transitional function of DG to CA3 in the hippocampus

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Progress in Natural Science:Materials International 2007年第12期17卷 1436-1444页

作者： Yan Chuankui1 and Liu Shenquan2.1. Department of mathematics, Hangzhou Normal University, Hangzhou 310036, china 2. Department of {2. mathematics, School of Mathematical Sciences, South china University of Technology, Guangzhou 510640, china) Department of mathematics Hangzhou Normal University Hangzhou 310036 China Department of applied mathematics School of Mathematical Sciences South China University of Technology Guangzhou 510640 China

Using single cell channel model, the transmission features of CA3-DG network in the hippocampus are investigated. The influence of the stimulation on discharge pattern of pyramidal neurons is analyzed, which shows that it starts with period spiking discharges, followed by period-doubling bifurcation to chaos, and period 3 discharge evolving into chaos, and ultimately a period of bursting discharges. By the synaptic model, the CA3-DG network model is constructed, which analyzes the summation of postsynaptic currents in the network, the influence of postsynaptic current on discharge rhythm as well as the mechanism of bursting discharges. The strong capacity of spatiotemporal encoding in the network indicates the features of CA3 network during the information transmission process in the hippocampus. The modeling result with time delay of the synaptic transmission is in accordance with the experimental phenomena of action potential in the hippocampus.

关键词： hippocampus CA3-DG period-doubling bifurcation chaos.

Empirical likelihood confidence regions of the parameters in a partially linear single-index model

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Science china mathematics 2005年第10期48卷 1333-1348页

作者： XUE Liugen~1 & ZHU Lixing~2.1. College of applied Sciences,Beijing University of Technology,Beijing 10002.,china 2. Department of {2.,Hong Kong Baptist University,Hong Kong,china 1. College of applied Sciences Beijing University of Technology 100022 Beijing China 2. Department of mathematics Hong Kong Baptist University Hong Kong China

In this paper, a partially linear single-index model is investigated, and three empirical log-likelihood ratio statistics for the unknown parameters in the model are suggested. It is proved that the proposed statistics are asymptotically standard chi-square under some suitable conditions, and hence can be used to construct the confidence regions of the parameters. Our methods can also deal with the confidence region construction for the index in the pure single-index model. A simulation study indicates that, in terms of coverage probabilities and average areas of the confidence regions, the proposed methods perform better than the least-squares method.

关键词： partially linear single-index model, empirical likelihood, confidence region, chi-square distribution, coverage probability.

On the periodic solutions of a type of differential-iterative equations

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Chinese Science Bulletin 1998年第3期43卷 204-206页

作者： GE Weigao 1, LIU Zhengrong 2.and YU Yuanhong 3 1. Department of applied mathematics, Beijing Institute of Technology, Beijing 100081,{2. 2. Department of mathematics, Yunnan University, Kunming 650091,{2. 3. Institute of applied mathematics, C Department of applied mathematics Beijing Institute of Technology Beijing China Department of mathematics Yunnan University Kunming China Institute of applied mathematics Chinese Academy of Sciences Beijing China

Sufficient conditions for the existence of periodic solutions to a type of nonautonomous differential_iterative equations are given.

关键词： differential_iterative equation periodic solution fixed point.