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25 March 1993, Volume 10 Issue 1 Previous Issue    Next Issue

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THE ASYMPTOTIC EXPANSION AND EXTRAPOLATION OFTHE SOLUTION OF DU FORT-FRANKEL SCHEMEFOR DIFFUSION PROBLEMS Yang Qingmin, Gong An, Xie Jian 1993, 10(1): 1-8.  Abstract ( )   PDF (425KB) ( )   In this paper, we build the asymptotic expansion of solution of Du Fort-Frankel scheme for diffusion problem and then use extrapolation. The accruacy of the extrapolation solution may achieve O(τ2+h4) and the limitation of consistency is improved greatly.

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A MATHEMATICAL MODEL OF AN URBAN FIRE-SPREAD AND COMPUTER SIMULATION Huang Weizhang, Zhang Suochun, Lei Guangyao, Wang Yiren 1993, 10(1): 9-19.  Abstract ( )   PDF (744KB) ( )   The objective of this study is to develop a mathematical model for calculating the initiation and spresd of fire resulting from an attack on an urban area, and to apply the model for predicting the fire-depentdent fire damage to an assumed city. The numerical test is obtained valuable information by using the parameters of fire spread from Japanese Hiroshima.The model to be developed is included——to determine description for a simplified urban,to take account of fire spread by radiation and firebrands in terms of statistical data, and to develop a computer program to perform the numerical simulation.

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A COMPARISON BETWEEN THE FAST-FISSION BLANKETAND THE SUPPRESSED-FISSION BLANKETOF FUSION-FISSION HYBRID REACTOR Liu Chengan 1993, 10(1): 20-24.  Abstract ( )   PDF (315KB) ( )   For the fusion-fission hybrid Reactor producing nuclear fuel as its main purpose, the two distinct design could be adopted: fast-fission blanket and suppressed-fission blanket. They possess both individual advantage and deficiencies.Taking the two typical blanket configuration as examples, the neutronics calculation and the contrast analysis have been performed.The results in this paper could be taken for reference when doing conceptual design and study of a technological feasibility, a safety and economics.

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A THREE-DIMENSIONAL CIRCULATION MODEL AND ITS APPLICATION Dou Zhenxing, Yang Lianwu 1993, 10(1): 25-36.  Abstract ( )   PDF (726KB) ( )   Present paper intents to provide a three dimensional circulation model which is universally applicable for continental shelf. The governing equations which are the three-dimensional, time-dependent and free surface, nonlinear Navier-Stokes equations are transformed into α,β,σ, t* coordinate system for increasing the resolution in vertical direction in shallow region and are solved together with their boundary conditions by finite difference technique. A space staggered grid system is employed for computation. For computational effeciency the model makes use of the concept on process-splitting which partition the fluid flow into two parts, and whereby the volume transport and vertical velocity shear are solved separately, The fast moving external gravity waves are treated by semi-implicit scheme (ADI )for advantage of great time-step and computational stability. An implicit scheme in vertical direction with leapfrog difference in time stepping is used to calculate the slow moving internal gravity waves. The finite difference equations can be demonstrated to by of second order accuracy in space and in time. The model has a good computational stability.To illustrate the application of present model to continental shelf sea, the tidal current in the Bohai Sea is computed. A good agreement of the computed results to the observed is achieved.

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VARIATIONAL PERTURBATION CALCULATIONS FORHYDROGEN-LIKE ATOMS IN THE SMALL ANDTIME HARMONIC ELECTRIC FIELD I:THE GROUND STATE Li Guiqin, Ding Peizhu 1993, 10(1): 37-45.  Abstract ( )   PDF (587KB) ( )   In this paper the variational perturbation scheme based on hydrodynamic analogy to Schrödinger equation is adopted and the perturbed wavefunctions for the hydrogen-like atoms H, He+, Li+2, Be+3,B+4 in their ground state (100)in a small and time harmonic electric field and the polarizabities and the 1st resonant frequences are calculated. And the variation of the electronic probability with time is also discussed. It is shown that the calculated results of the polarizability and the 1st resonant frequence are in good agreement with the exact data and that ∈ and S play the same important role in the calculation of the polarizability by using this scheme.

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VARIATIONAL PERTURBATION CALCULATION FOR HYDROGEN-LIKE ATOMS IN THE SMALL AND TIME HARMONIC ELECTRIC FIELD Ⅱ:THE EXCITED STATES (21±1)AND (32±2) Li Guiqin, Ding Peizhu 1993, 10(1): 46-54.  Abstract ( )   PDF (560KB) ( )   In this paper as continuation of our first paper [4], the variational perturbation scheme based on hydrodynamic analogy to Schrödinger equation is adopted and the perturbed wavefunctions for the hydrogen-like atoms H, He+, Li+2, Be+3,B+4 in their excited states (21±1)and (32±2)in a small and time harmonic electric field and the polarizabilities and the 1st resonant frequences are calculated. And the variation of the electronic probability is also discussed. It is shown that the calculated results of the polarizability and the 1st resonant frequence are in good agreement with the exact data. And it is further shown that ∈ and S play the same important role in the calculation of the polarizability using this scheme.

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Calculation of Atomic Structurefor Arbitrary Temperature and Matter Density Sun Yongsheng, Meng Xujun, Li Shichang 1993, 10(1): 55-61.  Abstract ( )   PDF (364KB) ( )   Schrödinger wave equation is solved for arbitrary matter density and temperature in the Hartree-Fock-Slater (HFS) self-consistent field method. In order to describe relativistic effects, the mass-velocity, the Darwin and spin-orbit coupling terms are included in the wave equation. Some of our results are compared with experimental data and with other theoretical model, the present results are consistent with experiment better and are close to that of Reference.

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A FOURTH-ORDER DISSIPATION EXPONENT-TYPE SCHEME OF ONE-SIDED APPROXIMATION FOR SOLVING CONVECTIVE DIFFUSION EQUATIONS Lu Junan, Yang Yisong 1993, 10(1): 62-68.  Abstract ( )   PDF (387KB) ( )   In this paper a fourth-oder dissipation exponent-type scheme of one-sided approximation for solving convective diffusion equations is derived. The theoretical results on the stability and the properties of one-sided approximation and fourth-oder dissipation of this scheme have been presented. The relations of this scheme and finite analytic method is also obtained. Some numerical examples are qiven.

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RECONSTRUCTION OF PLASMA EQUILIBRIUMIN TOKAMAK Zhu Sizheng 1993, 10(1): 69-75.  Abstract ( )   PDF (467KB) ( )   A method is described for reconstructing tokatnak equilibria from measurements of external magnetic signals and also of the total plasma current and average poloidal beta. Calculations are performed to determine circular, non-circular and diverted configurations and to reconstruct different types of current profiles. Also carried out is a numerical study of the effect of measurement errors and arrangement of detectors on the quality of reconstruction.

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RECURRENT CALCULATION OF SOLITONS SOLUTION OF THE NONLINEAR Schrödinger EQUATION Wang Binquan, Liu Zhongzhu 1993, 10(1): 76-80.  Abstract ( )   PDF (318KB) ( )   We present a new method to obtain soliton's numeric solution from the NLS equation, it is a recurrent method. The practice prove it not only gives good soliton's figure simply and fastly but also saves time.

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MORSE-CG CODE THREE-DIMENSION CALCULATIONOF THE BENCHMARK NEUTRON POROSITYWELL-LOGGING Deng Lii 1993, 10(1): 81-86.  Abstract ( )   PDF (420KB) ( )   It is a valid method by using the Monte Carlo method to calculate three-dimensional porosity well-logging problems. This paper gives out the calculated results of the benchmark neutron well-logging problems with porosity 1% and 20% from the MORSE-CG code which the restart capability have been added into it, and thd comparison of it with MCNP and McDNL results and computing time. Results indicate that the three cokes give the same results within calculated standard deviations.

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MONTE CARLO SIMULATION OF AN ELECTRON SWARM WITHIN THE CATHODE REGION OF A GLOW DISCHARGE IN ARGON Sun Jizhong, Gong Ye, Wang Dezhen 1993, 10(1): 87-94.  Abstract ( )   PDF (494KB) ( )   In this paper, electron movement in the cathode fall region of a glow discharge in Argon has been simulated using the three dimensional Monte Carlo method, which has taken advantage of a null-collision technique. The electron distribution functions and the macroscopic electron parameters including the mean electron energy, the mutiplication coefficient and the Townsend inoizion coefficient are given and compared with those obtained with the one dimensional computer model. The results have shown that the angular scattering has significantly affected the electron behavour.

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NUMERICAL SIMULATION OF VISCOUS FLOWS OVER RE-ENTRY VEHICLES WITH A HIGH RESOLUTION SCHEME Zhou Weijiang 1993, 10(1): 95-102.  Abstract ( )   PDF (440KB) ( )   TVD scheme is one of the most advanced schemes for investigating supersonic and hypersonic complex flows in which shock wave is one of important properties up to date. In present paper, axisymmetric viscous flows about three indented nosetips and hypersonic flow about a blunt-cone body (θ=10°) at angles of attack were simulated with a two-order windward TVD scheme. High quatitive shocks and surface pressure distributions agreed with experiments and results from space-marching method were obtained. It is also demonstrated the unique advantages of present method for computing complex flows over re-entry vehicles.

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CROSS SECTIONS OF ELECTRON IMPACT EXCITATIONFOR He-LIKE IONS Qiu Yubo, Jia Baolin 1993, 10(1): 103-111.  Abstract ( )   PDF (504KB) ( )   The electron impact excitation of He-like ions is studied by distorted wave method. The HFS wave functions of the target are used. We have calculated the transitions between the 11S and 21,3S, 21,3P states for some He-like ions. Results are presented in terms of collision strengths. The incident electron energies are from threshold to x=10. The results are compared with the data avaible. It is shown that the results are satisfied in most cases.

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COMPLETE PARTITION AND ITS ALGORISM Liu Hongmin, Sa Benhao 1993, 10(1): 112-116.  Abstract ( )   PDF (270KB) ( )   The method of complete partition commonly used in the study of physics and other sciences is discussed and a FORTRAN-77 programme of computating the complete partition is given.

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STUDIES ON THE SHORT-RANGE INTERACTION POTENTIAL BETWEEN H2 MOLECULES Tang Haixing, Zhou Maotang, Xin Bing, Zhu Yongxiang 1993, 10(1): 117-119.  Abstract ( )   PDF (205KB) ( )   The programmed quantum mechanical CI method in Gaussian 82 program, which is publicly recognized, is used in this paper. An ab initio calculation is made, on the basis of using a relatively large basis set 6-31G**, on the four kinds of configuration formed by the two H2 molecules. In so doing, the existence of the abnormal structure within the short-range area of the interaction potential curve is confirmed. In this paper, the rules of H2 molecule bond length changing with the distance between center of mass of two molecules and the corresponding charge redistribution are also reported.

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A MATHEMATICA PROGRAM FOR CALCULATING γ MATRIX TRACE IN QUANTUM FIELD THEORY Ji Yonghua, Ma Wengan 1993, 10(1): 120-122.  Abstract ( )   PDF (194KB) ( )   A computer program Gamma, which is based on the computer symbolic algebra manipulation system mathematica, is introduced. This program has defined γ matrix expressions and their calculations. It is very convenient to calculate Feynman diagrams using this program.