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25 September 1990, Volume 7 Issue 3 Previous Issue    Next Issue

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GREEN FUNCTIONS USED FOR STUDYING UNSTEADY STOKES FLOW Cao Nianzheng, You Renran, Chen Yaosong 1990, 7(3): 257-267.  Abstract ( )   PDF (542KB) ( )   Using BEM to solve vibrating or unsteady Stokes flow is very attractive. At first we derive the Green functions for 2D and 3D. Then we deduce the relative formula, the explicit expression for pressure and the boundary integral equation. The integral equation is discretized into a set of linear algebric equations. In the case of 2D, the influence coefficients of the segment to itself are integrated analytically. In order to check such BEM, an example with analytical solution already exists is solved numerically. The result shows that the method based upon our Green functions is perfect.

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A RADIANT TEMPERATURE NUMERICAL METHOD FORLASER-PLASMA DIAGNOSTIC USING SXRSCWITH ABSORPTION METHOD Tang Yongjian, Ding Yiaonan, Zheng Zhijian, Chen Xiaofeng 1990, 7(3): 268-274.  Abstract ( )   PDF (403KB) ( )   An numerical method was developed for measuring radiant temperature using a set of absorption-foils coupled to soft x ray streak camera, SXRSC, in laser plasma experiments. An numerical code, SCC, was given. An x-ray intensity ratio vs temperature was calculated for Parylene, C3H6, Formvar, Mylar and Aluminum. A suitable range of the measuring temperature was discussed to some absorber.

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AN IMPLICIT FINITE DIFFERENCE SCHEME FORSIMULATION OF COMPRESSIBLE TURBULENCEFLOWS IN A S-SHAPED CHANNEL Jiang Zonglin 1990, 7(3): 275-282.  Abstract ( )   PDF (510KB) ( )   In this paper, an implicit and upwind incremental Block-Line-Gauss-Seidel Method is developed for solving compressible Navier Stokes equations in the Body-Fitted coordinate system. The computational solutions of the internal compressible turbulence flow have been obtained by the method with a two-layer eddy viscosity model employing a Baldwin-Lomax algebraic turbulece model. Numerical experiments show that the computational procedure is of good stability and convergence. Numerical results of the Poissuil flow and Couette flow are good agreement with its analytic solution and computational results of flows in S-Shaped channel with different wall curvature are satisfactorily.

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THE STEADY AND PERIODIC SOLUTIONS OFTHE 5-DIMENSIONAL CONVETION MODEL OBTAINED BY THE CONTINUATION ALGORITHM Liu Shida, Xin Guojun 1990, 7(3): 283-293.  Abstract ( )   PDF (683KB) ( )   The continuation algorithm is applied to calculate the steady and periodic solutions of the 5-dimensional convection nonlinear dynamical system. The real bifurcation points curve, limit points curve and Hopf bifurcation points curve of the model are drawn in the parameter plane Ri-Re. The bifurcation diagram.is obtained. The different type of stable solutions such as stationary attractor, periodic attractor and chaotic attractor and so on exist in the different blocks or regions in the bifurcation diagram. Through analysing the bifurcation course of the steady and periodic solutions curve, the physical transitions both from steady state to periodic state and from periodic state to chaotic state which happened in the atomspheric stratified layer are discussed.The numerical computation results show that the continuation algorithm is a very effective computational method for researching into the bifurcation and dissipative structure of a nonlinear-dynamical system.

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THE MIXED FINITE ELEMENT METHOD FOR AXISYMMETRIC STOKES FLOW ON UNBOUNDED DOMAINS Wu Wangyi, Liang lei, Guo Xiangdong 1990, 7(3): 294-302.  Abstract ( )   PDF (447KB) ( )   This paper deals with the finite element approximation of the axisymmetric Stokes flow on unbounded domains. In order to overcome the difficulties caused by the unbounded domains, the finite element method is combined with the classical analytical method and the equivalent boundary value problem on bounded domains is obtained, which is solved numerically by the finite element techneque. As an example, the Stokes flow around the sphere is calculated and the error estimate of the approximate solutions is given.

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3-DIMENSIONAL NUMERICAL METHOD FOR THECONVECTION-DIFFUSION PROBLEM OF HEATEDDISCHARGE ACTED ON BY TIDE AND STREAM Zhang Diming, Zhan Jiemin 1990, 7(3): 303-312.  Abstract ( )   PDF (457KB) ( )   This paper gives a numerical method for the convection-diffusion problem of heated discharge acted on by tide and stream. Numerical results have shown that it is a very effective method.

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BOUNDARY ELEMENT ANALYSIS OF NONLINEAR PROBLEMS IN TRANSIENT HEAT CONDUCTION Yao Shouguang, Zhu Deshu, Kong Xiangqian 1990, 7(3): 313-320.  Abstract ( )   PDF (417KB) ( )   In this paper, Kirchhof's transform is employed to convert time dependent heat conduction problems involving varing material properties and mixed and nonlinear radiation boundary condictions into a linear one. Appling weighted residual method to transform the problem in boundary integral equation. Discretization of this equation gives a system of algebraic equations with linear matrix and nonlinear right band sides. Such set of equations can be solved itera-tively. The two dimension linear-nonlinear transient temperature field analysis program is developed, and several numerical examples are computed in the paper.

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THE EQUATION OF STATE AND SN EXPLOSION Wang Yiren, Li Hong, Yao Jin, Wang Weizhong 1990, 7(3): 321-331.  Abstract ( )   PDF (688KB) ( )   There is a restriction to the solution of the epuation of θ (the ratio between the density of the nuclear matter and the density of the nuclear matter at saturation) in the J. Cooperstein's equ ation of state. Starting from the expression of nucleons pressure near the saturation density at zero temperature, a expression of nucleon internal energy is obtained by us. the re striction mentioned above in J. Cooperstein's equation of state has been removed by substituting the expression of nucleon internal energy obtained by us for the expression used by J.Cooperstein. Me present results of hydrodynamic cal culation of core collapse and subsequent shock wave formation and propagation using the equation of state of us and using the 15M⊙ initial model of WZW.The relesse of gravitational binding energy of core can be increased by proper softening the equation of state above the sqturation density of nucl ear matter.

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THE MULTI-CONFIGURATION DIRAC-FOCK CALCULATION OF F-LIKE Ce、Gd、Lu、Th、U IONS FOR LEVEL AND COHERENT RADIATION WAVELENGTHS Zhang Tongfa, Bai Yunxin, Pan Shoufu 1990, 7(3): 332-340.  Abstract ( )   PDF (568KB) ( )   In this paper, by using the relativistic multi-configuration Dirac-fock extended average level model, we calculate 113 levels of all the 2s22p5、2s22p43l、2s2p53l and 2p63l configuration of lasing matter with the F-like type plasma,Ce,Gd, Lu, Th, U ions, which can produce coherent radiation feasibility of soft Xray, and results are prented for all allowed tranitory strong coherent radiation wavelength value from the singly excited M-subshell states to the tow-lying 2s22p(2P3/2,2P1/2) configuration and 2s2p6(2S1/2) configuration.

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NUMERICAL SOLUSIONS OF THE INITIAL-BOUNDARYVALUE PROBLEMS OF THE ROTATION MODIFIEDKADOMTSEV-PETVIASHVILI EQUATION Tang Shimin, Roger Grimshaw 1990, 7(3): 341-354.  Abstract ( )   PDF (965KB) ( )   Grimshaw derived the rotation modified Kadomtsev-Petviashivili Equation (RKP Eq.) to discribe long surface or internal waves in the presence of rotation. The initial-boundary value problems of RKP equation are studied numerically in this paper. It is shown that solitary-like waves prapogating to the right can be found, whose amplitudes decay in the direction perpendicular to the direction of prapogation and the wave fronts are curvedback. The solitary waves remain unsteady and are always accompanied by Poincare waves travelling to the left.These effects are more noticeable as the effects of rotation are increased.

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NUMERICAL SIMULATION OF VISCOUS FLOW AROUND FORWARD FACED STEP wang Li, Fu Dexun 1990, 7(3): 355-362.  Abstract ( )   PDF (442KB) ( )   Laminar compressible flow near a farward faced step is sumulated numerically using the Navier-Stokes equations. Influence of Mach number and Reynolds number on flow character is studied. The computed results are compared with experiments, and agreement is satisfactory.

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THE NUMERICAL SIMULATION OF THE ELOW PASTA FINITE FLAT PLATE Zhu Jinghui 1990, 7(3): 363-370.  Abstract ( )   PDF (556KB) ( )   The flow past a finite flat plate is simulated numerically by vortex method in this paper. The velocity field is calculated around the flat plate with length 1 which started impulsively with a constant velocity.A Laplace eguation appeared in vortex method is solved by conformal transformation.The singular points in the transformation are treated specially,finally, we obtain a periodic numerical solution which agree quite well with the experimental results.

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AN ESTIMATE OF OPTIMAL MULTIPLICATOR Li Zuoxin, Lu Qingtang 1990, 7(3): 371-374.  Abstract ( )   PDF (221KB) ( )   Take a modulo of large primitive number, then choose different primitive roots as multiplicators of the modulo, get a generator of sequence sets of good PRN, it is called LiG, This paper presents an estimate of optimal multiplicate with the modulo 231-1 by whole sample deviation formula of PRN in the case of mentioned above.

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MORSE-CGT* MONTE CARLO RADIATIONTRANSPORT CODE WITH THE CAPABILITY OF THETORUS GEOMETRIC TREATMENT Deng Li 1990, 7(3): 375-384.  Abstract ( )   PDF (548KB) ( )   This paper introduces the combinatorial geometry package CGT with the capability of the torus geometric treatment. It is get by developing the combinatorial geometry package CG. The CGT package can be transplanted to those codes which the CG package is being used and makes them also with the capability. The MORSE-CGT code can be used to solve the neutron, gamma-ray or coupled neutron-gamma-ray transport problems and time dependence for both shielding and criticality problems in torus system or system which is produced by arbitrary finite combining torus with torus or other bodies in CG package and it can also be used to design the blanket and compute shielding for TOKAMAK Fusion-Fission Hybrid Reactor.