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25 June 1988, Volume 5 Issue 2 Previous Issue    Next Issue

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NUMERICAL MODELLING OF FLOW FIELD IN A TIDAL RIVER AND THE NEAR FIELD OF INTAKE FOR A NUCLEAR POWER PLANT Cai Ti-qing, Qin Su-di, Fan Jia-hua, Wu Jiang-hang 1988, 5(2): 129-138.  Abstract ( )   PDF (602KB) ( )   This paper concerns with numerical modelling of flow field in a tidal river and in the vicinity of intake of a nuclear power plant. The hybrid method of fractional steps presented in[1] was adopted in this modelling. In order to simulate the local flow field nearby the water intake meticulously, the technique of the match of the coarse and fine grids was used. The numerical results are in good agreement with the measurements of the main current. The local flow field nearby the intake provides the assessment of the sediment transport characteristics in the vicinity of intake of the nuclear power plant with the flow data in detail.

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CALCULATION FOR LASER-PRODUCED PLASMAS CONDITIONS OF THIN MIDDLE-Z TARGETS——COMPUTIONAL SIMULATIONS OF THE INTERACTIONS FOR LASER WITH PLASMA (Ⅰ) Peng Hui-min, Zhang Gui-ping, Sheng Jia-tian, Shao Yun-feng, Zhang Yin-chun 1988, 5(2): 139-147.  Abstract ( )   PDF (499KB) ( )   In this paper we used one-dimentional non-LTE laser irradiated code to simulate the laser-produced plasmas conditions of thin middle Z targets with high intensities (about 1013W/cm2)irradiation.Following physical processes are considered; bremsstrahlung,radiative ionization,collisional ionization by electrons and their inverse processes, Compton scatterion. Fokker-Planck approximtaion is used in Compton scattering; The thermal flux limits are taken for electrons and ions in the calculating and the multigroup flux-limited diffusion approximation is taken for the radiative transport equations.Using average-atom model to calculate the population probabilities of atoms. Laser absorption via inverse bresstr-ahlung is considered to be the most important in our simulation.Using, laser beams with intensities 5×1013W/cm2 and 1×1014 W/cm2, λL=0.53μm, τ=450ps to irradiate thin Se target from single-side and double-sides separately, the computational results for laser-produced plasmas conditions are good agree with experimental results.

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THE NUMERICAL METHOD FOR SOLVING THE RATE EQUATIONS OF ELECTRON'S AVERAGE OCCUPATION PROBABILITIES BY USING MULTIPLE-TIME-SCALE PERTURBATION THEORY Chen Guang-na, Chang Tie-qiang 1988, 5(2): 148-162.  Abstract ( )   PDF (788KB) ( )   This paper presents the numerical method for solving the rate equations of electron's average occupation probabilities by using multiple-time-scale perturbation theory.It is especially suitable for lower levels of elements, Since in that case the transition between neighbouring bound energy levels could be considered as fast, the others as slow. Under some reasonable physical assumptions the method leads to the analytic expressions for Pn as functions of the number of free electron, ns.As a result, in stead of solvingstrong stitff ordinary ditferential equations of (dpn)/(dt), we just need solving thedifferential equation for ne and the algebraical equations for Pn. Therefore the problem is much simplified with avoiding the computation of Jacobi iaverse matrix which generally appears is the implicit schemes.

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AN ERROR ESTIMATE FOR CALCULATING DAWSON'S INTEGRAL Gong Ye 1988, 5(2): 163-168.  Abstract ( )   PDF (291KB) ( )   The approximate expression is oktained for calculating Dawson's integral in this paper and given eJoquent proof of theory to estimate maximum error effeetively.

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THE SOLUTION OF MICRO LATEROLOG PROBLEM USING BIEM Li Nai-hua, Tang Yong-Fu 1988, 5(2): 169-179.  Abstract ( )   PDF (556KB) ( )   In this paper the Linear model for micro laterolog problem is discussed by using BIEM (Boundary Integral Equation Method). The computting results show that the contour of voltage distribution is satisfactory, and provide an evidence for designing optimum micro laterolog apparatus.

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NUMERICAL ANALYSIS OF THREE DIMENSIONAL LUBRICATION PROBLEMS Han Qing-shu, Lu Shou-zhi 1988, 5(2): 180-188.  Abstract ( )   PDF (540KB) ( )   In this paper, solutions of three-dimensional lubrication problem of bearing are presented, The basic equations are converted into boundray integral equations using Green's function me thod. Spatial triangular boundary elements and the isopara metric elements with six nodes are used to discretize the boundary of the solution domain. The integral equations are solved numerically. The velocity and pressure fields and the surface stress are determined. When we are compared with analytic solutions, this method has higher accuracy. Some satisfactory computation results for other typical problems are indicate the affectiveness of the method for numerical analysis of these kinds of problems.

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A SIMULATION FOR ?-SPECTROMETER WITH COMPTON SUPPRESSION SHIELDS Feng Zheng-yong, Wang Shao-shun, Xiao Chen-guo 1988, 5(2): 189-196.  Abstract ( )   PDF (537KB) ( )   The physics process of γ-detection of γ-spcctrometer with Compton suppression shields has been simulated using Monte-Carlo method. The results calculated for the γ-source 137Cs with energy of 662 keV and for the cascade γ-source 60Co with energies of 1173 keV and 1332 keV were in agreement with measurements. This work should be useful in the physics design, for γ-spectrometers with Compton suppression shields.

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THE PIECE-WISE BOUNDARY-LAYER DISTRIBUTION METHOD FOR HYPERBOLIC CONSERVATIVE LAW SYSTEM Wen Yu-lian 1988, 5(2): 197-210.  Abstract ( )   PDF (743KB) ( )   A new kind of high-order Godunovian scheme is suggested here, inwhich the hyperthesis of piece-wise linear or parabolic interpolation polynomial[9],[10]to construct the distribution with the discontinuity on net boundary is improved in this paper by introducing a piece-wise boundarylayer distribution. This kind of distribution is piece-wise montone and differentiable,so it is unneseccery to check the monotonuity like in PPM and MUSCL schemes.The new scheme called PBLM has hihg-order accuracy the same as PPM scheme, even on the points on which the accuracy only has 1-order in PPM scheme. The results of l-dimmensional shock tube show that the spread of shock in PBLM is thiner than that in PPM and the computational time is equivalent. Just as PPM,for PBLM scheme about 2%-4% oscillations occur behind the shock. The additional dissipation should be added.

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A DIMENSIONAL REDUCTION METHOD FOR INCOMPRESSIBLE FLUID DYNAMICS Ⅲ、SECOND ORDER ACCURATE FINITE ELEMENT SCHEMES Yu Xin 1988, 5(2): 211-220.  Abstract ( )   PDF (504KB) ( )   This paper is the 3rd in a series of papers in-which we present a new finite element method for incompressible fluid dynamics-a dimensional reduction method.Here we discuss a class of finite element schemes which contain some second order accurate schemes and the schemes discussed in[4].

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OPTIMUM HERMITEAN LNTERPOLATION OPERATOR IN THE W22 SPACE Wu Bo-ying, Cui Ming-gen, Deng Zhong-xing 1988, 5(2): 221-231.  Abstract ( )   PDF (507KB) ( )   In this paper we investigated the function space W22 which has a regenerate nucleus. We obtained a finite expression of the regenerate nucleus and used it to construct a concrete expression of the optimum Hermitean interpolation operator. It was also proved that, as the density of the node system increases infinitely, (H2nu)(x) and (H2nu)'(x) uniformly converge to u(x) and u'(x), respectively, and the error decreases to zero monotonically, under the Sobolev norm.

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MONTE CARLO STUDY FOR SPIN SYSTEM USING RANDOM LATTICE MODEL Yang Qing-jian, Lou Yuan-dan 1988, 5(2): 232-234.  Abstract ( )   PDF (189KB) ( )   Using a new spin glass model-random Lattice model, MC Simulation has been calculated for spin glass system Cu0.995Mn0.00 5, It is found that there exists a sharp cusplike peak in the low-field susceptibility and a broad round peak in the magnetic specific heats.

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MONTE CARLO STMULATION OF PHYSICAL SPUTTERING Cui Fu-zhai, Li Wen-zhi, Li Heng-de, Zheng Li-ping 1988, 5(2): 235-240.  Abstract ( )   PDF (409KB) ( )   The Monte Carlo program TCIS simulating the transport of energetic ions and atomic collision cascades in solids has been used to investigate some problems on physical sputtering. Atomic collisions at the region of low energies contribute to the most of the sputtering yield. At low energies, the time integral τ of the atomic collision calculation will not be a negligible quantity. In this paper, the influence of τ on sputtering yield is studied. The main features of the Monte Carlo code are introduced. Some results of computation concerning sputtering are given. The information about physical sputtering at atomistic level can be obtained by this code,which are useful in the research of sputtering mechanism.

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THE IMAGINARY ELASTIC WALL METHOD IN SIMULATION OF PARTICLE TRANSFERENCE Feng Zheng-yong 1988, 5(2): 241-245.  Abstract ( )   PDF (350KB) ( )   Use of imaginary elastic wall method to simulate the action of moving particle's on the wall of vessel at balance state was suggested. The physical bases, the efficiency of saving CPU time of the method were discussed. The extra error caused by using imaginary elastic walls in quasi-balance states was estimated also. In the last part of this article an example by using the method was placed out.

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ICCP was hold in Beijing 1988, 5(2): 247-248.  Abstract ( )   PDF (129KB) ( )   International Conference on Computational Physics (ICCP)was hold in Beijing during 1-5 June, 1988. Two hundred scientists from the USA, Japan,USSR, West Germany, Britan, and China attended the conference.