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25 March 1989, Volume 6 Issue 1 Previous Issue    Next Issue

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MOMENT-METHOD SOLUTION OF STATIC-ELECTRIC BOUNDARY-VALUE PROBLEMS DESEN FAN 1989, 6(1): 1-8.  Abstract ( )   PDF (481KB) ( )   A new approach to numerical solution of the boundary-value problems of static-electric fields, the Modified Green Function kernel integral equation and its moment-method solution, is presented. Due to the significient compression of integration region of the integral equations, the present approach is numerically effective and is especially suitable to the problems with infinite conductor boundary. The emphasize is paied on the analysis of transmission lines, which are the typical boundary-value problems of two-dimension and are very useful to the high-frequency and microwave techniques as well.The analysis method to the 3-dimensional counterparts of the problems is similar, and.the extended applications to the problems of variable electromagnetic fields are proved successful.

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METHODS FOR COMPUTATION OF PLASMA DISPERSION FUNCTION Xu Ying 1989, 6(1): 9-18.  Abstract ( )   PDF (559KB) ( )   Based on the derivation of series expressions for error function of complex argument ξ=x+iy, the methods for computation, to high accuracy, of plasma dispersion function Z and jts derivative Z' in the region |y|≤1, |x|≤10 have been given in this paper. Furthermore, the plasma dispersion function and the suitable methods for its computation are studied systematically in varisus regionsl of complex ξ Plane; the satisfactory results are obtained on VAX-11/750 computer; these results, the used methods and its accuracy have been disccused; the fundamental behavior of Z and Z' for y≥0 and y<0 have been discribed respectively in the paper.

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THEORIES AND CALCULATION METHODS OF ELECTRON (KEV AND BELOW KEV)SCATTERING IN SOLIDS AND RELATED APPLICATIONS He Yancai, Chen Jiaguang 1989, 6(1): 19-26.  Abstract ( )   PDF (582KB) ( )   The theories and the calculation methods methods of electron scattering with keV and below keV energy by Monte Carlo simulation are discussed in this paper and the applications in the important fields i.e. electron microscopy and electron beam lithography are introduced.

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STATISTICAL THEORY OF FASHIONABLE COLORS Feng Chingzhen 1989, 6(1): 27-37.  Abstract ( )   PDF (705KB) ( )   Fashionable color of dresses can be regarded as a certain social phase transition. In this paper a Fokker-Planck equation, is derived to describe these phenomena. The bifurcation processes of deterministic equations which describe dynamical behaviors of subsystems, and the corresponding different probability distribution configurations of Fokker-Planck equation which can be regarded as the random description of bifurcation processes of a social system are studied in.detail. Computational results and its interpretations are presented in the end.

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A NONLINEAR STABILITY ANALYSIS FOR NUMERICAL SIMULATION OF TWO PHASE FLOW Zhang Zixing, Qu Debin, Fan Jiang 1989, 6(1): 38-48.  Abstract ( )   PDF (607KB) ( )   In This paper, nonlinear stability has been analysed for numerical simulation of two phase flow using explicit, completely implicit, semi-implicit with old derivative and semi-implicit with chord slope derivative. Several stability conditions are given by Van Naumann method, Through out Theoretical analysis and practical calculation, The above four appreaches of nonlinear problem are analysed and compared from several aspects. This recearch is important in mathematics and mcmerical reservoir simulation itself.

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THE NUMERICAL STUDY OF ELECTRIC FIELD NEAR THE PIC'S SIDE FRAME BY USING FINITE ELEMENT METHOD Zhang Ziping, Zhang Zili, Ma Wengan, Lin Zhirong, Chen Hongfang 1989, 6(1): 49-52.  Abstract ( )   PDF (274KB) ( )   This paper presents a numerical study of the electric field distortion near the side frame of Proportional Inclined Ghanber (PIC) ,which is made of G10 epoxy resin plate, by using the finite element method. The calculation results are quite consistent with experimental tests. An optimized design scheme for improving the gain efficiency uniformity of the anode signal wires near the side frame is proposed.

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THE MOLECULAR DYNAMICAL SIMULATION OF SHOCK WAVE PROPAGATION AND REFLECTION FROM FREE SURFACE IN TWO-DIMENSIONAL LATTICE Wang Jihai, Zhang Jinglin 1989, 6(1): 53-59.  Abstract ( )   PDF (461KB) ( )   The propagation of shock wave and it's reflection at free surface in two-dimensional lattice are considered and calculated by method of molecular dynamics. This lattice simulates the (1,0,0) plane for face centered cubic (f.c.c) or the (1,1,0)plane for body centered cubic(b.c.c).In the range of our calculation (up=10-75×104cm/sec), the oscillation of particle velocity is'nt decrescent. The shock wave velocity is a linear function of average particle velocity. After reflection, the average particle velocity near free surface is equal to twice the piston velocity approximately, which agrees with macroscopic phenomena. The particles at outer-most layer of free surface, get the large value of velocity and go away from this surface. It is also similar to the macroscopic phenomena of ejection. At the later stage of expansion, the particles in the interial region may lose connection between them, that corresponds to the microscopic fracture.

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A PARALLEL CALCULATION OF FAST FOURIER TRANSFORM AND ITS IMPLEMENTATION IN YH-1 COMPUTER Jiang Bocheng, Cheng Kemao 1989, 6(1): 60-66.  Abstract ( )   PDF (440KB) ( )   In this paper, We studied the parallel Computational algorithm of Fast Fourier Transform and its implementation in YH-1 Computer. The result of Computation indicated that developed parallel algorithm is very effective and the efficiency of yecter operation has been enhangced by dozen times as Compared with Conventional scalar operation of FFT.

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Si(100)2×1 SURFACE RECONSTRUCTION BY SIMPLEX METHOD Zi Jian, Zhang kaiming 1989, 6(1): 67-70.  Abstract ( )   PDF (262KB) ( )   The positions of atoms untill fifth layers of the reconstructed Si(100)2×1 surface are studied by simplex method. In addition, the reconstractions of diamond and Ge(100)2×1 are also investigated.

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SIMULATION OF SPIN GLASS SYSTEM WITH TWO DIMENSIONAL RANDOM LATTICE MODEL Yang Qianjing, Lou Yuandan 1989, 6(1): 71-76.  Abstract ( )   PDF (393KB) ( )   Two dimensional random lattice model has been applied to spin glass system CuMn using Monte Carlo method. A new, method was developed for quick producing the 2D random lattice. Physical quantities susceptibility and specific heat were calculated under various conditions. The finite size problem was also tackled.

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THE GRAPHICAL OUTPUT METHOD IN COMPUTATIONAL PHYSICS——AN INTRODUCTION OF COMPUTER ANIMATION FOR SCIENCE AND ENGINEERING Wang Baoxing, Chen Shili, Yang Suxia 1989, 6(1): 77-83.  Abstract ( )   PDF (1256KB) ( )   The paper consists of four parts as follows: the graphical output problem in computational physics,graphical output by computer and computer graphics,computer animation for science and engineering, and institute of computer animation for science and engineering.

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THE NUMERICAL CALCULATION OF NATURAL CONVECTION IN POROUS MEDIUM WITHIN A CLOSED TRAPEZOIDAL CAVITY USING FINITE ELEMENT METHOD Chen Shannian, Liang Xifeng 1989, 6(1): 84-93.  Abstract ( )   PDF (665KB) ( )   The numerical analysis and calculation or natural convection in porous medium within a closed trapezoidal cavity using Galerkin finite element method are investigated in this paper. The range of the calculation is from conduction state to steady convection state(Ra:5~350). The distributions of flow field and temperature field and the curve of Nusselt number versus Rayleigh number are found for the different trapezoid decline angles of 0°, 5°, 10°, 30°and 45°. The effects of initial valus of iteration, relaxation factors and numble of element on numerical results are studied in detail. It is show when trapezoid decline angle increases the heat transfer intensifies and for the very small Rayleigh numble (c1=40) the steady flow will be formed. Finally, the results of the numerical calculation are discussed and compared with the vesults using other methods.

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SIP ALGORITHMS AND THE CHOICE OF THEIR PARAMETERS Liu Xingping 1989, 6(1): 94-103.  Abstract ( )   PDF (551KB) ( )   In this paper several SIP algorithms are proposed and the choice of their optimal parametens are analyzed in the case where the coefficient matrix of the linear system is an L-matrix with nonvanishing diagonal elements. Numerical results are given to illustrate that the convergence of our algorithms with the optimal parameters is better than that of other algorithms and parameters.

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A DIMENSIONAL REDUCTION METHOD FOR INCOMPRESSIBLE FLUID DYNAMICS Ⅳ.THREE DIMENSIONAL NAVIER-STOKES EQUATIONS Yu Xin 1989, 6(1): 104-116.  Abstract ( )   PDF (760KB) ( )   This paper is the 4th in a series of papers in which we propose a new finite element method for incompressible fluid dynamics-a dimensional reduction method. The divergence free space Vh is used as both the velocity solution space and the test function space in the momentum equation. Thus the pressure term disappear, the velocity vector can be solved(before the pressure).This paper presents a simple basis of Vh for a kind of first order finite element schemes solving three dimensional Navier-Stokes equations. It differs from the two dimensional problem on that the directly given "basis" Bh is linearly dependent. Therefore we must remove some functions from Bh so that it becomes linearly independent.All the removed functions form a "tree" in a sense.

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A METHOD FOR DETERMINING THE CONVERGENCE OF ITERATIVE METHOD AND THE CONVERGENCE OF SIP METHOD Hu Jia-gan, Liu Shing-ping 1989, 6(1): 117-125.  Abstract ( )   PDF (548KB) ( )   In this paper, a new method to determine the rate of Convergence of some terative methods for solving the systems of linear algebraic equations is proposed. The method is simpler and more effective than previons methods.It can show how the rate of convergence depends on some elements of the coefficient matrix of the system.Several iterative methods are considers and numerical results are given to illustrate our method and conclusions.