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25 March 1987, Volume 4 Issue 1 Previous Issue    Next Issue

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AN APPROXIMATE METHOD TO CALCULACE LONIZATION OF LTE AND NON-LTE PLASMAS Zhang Jun, Gu Pei-jun 1987, 4(1): 1-16.  Abstract ( )   PDF (881KB) ( )   When matter,especially high Z-element, is heated to high tempersture, it will be ionized many times. The degree of ionization has a strong effect on many plasma properties.So we need an approximate method to calculate mean ionization degree in many practical problems.In this paper, an analytical expression which is convenient for the approximate numerical calculation, is given by fitting it to the scaling law and numerical results of the ionization potential of Thomas-Fermi statistical model(1). In LTE case, the degree of ionization of Au calculated by the approximate method of Ref.(2) is in agreement with that of the averageion model. By extending the approximate method to Non-LTE case, the degree of ionization of Au is similarly calculated according to Corona model and Collision-Radiation model(C-R). The results of Corona model agree with the published data(1) quite well, while the results of C-R approach those of Corona model as the density is reduced and approach those of LTE as the density is increased. Finally, all approximately calculated results of ionization degree of Au and the comparision of them are given in figures and tables.

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SOLUTION OF PHASE CHANGE HEAT CONDUCTION PROBLEMS BY BEM WITH SPECIAL FUNCTION AS THE FUNDAMENTAL SOLUTION Wang De-ming, Chang Yan-ming 1987, 4(1): 17-22.  Abstract ( )   PDF (337KB) ( )   A BEM with special function as the fundamental solution was proposed to solve phase change heat conduction problems encontered in the process of semiconductor technology. By applying the Gauss integration formulas and asymptotic expansion of Bessel function, the integrations of special function, were carried out effectively.Results show that, compared with the conventional FEM, the developed method Possesses the merits of less computation time and higher accuracy. The method can be extended to three dimensional case with no difficulty.

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THE PARTIAL SEPARATION OF VARIABLES-FINITE DIFFERENCE METHOD FOR SOLVING DYNAMIC PROBLEMS OF ELASTIC WAVE He Bo-rong, Feng De-yi, Wang Zhan-biao, Wu Guo-you, Nie Yong-an 1987, 4(1): 23-34.  Abstract ( )   PDF (587KB) ( )   In this paper a new method is developed for solving the dynamic problems of elastic wave propagation. It is suitable for tayered media and buried point source model. The method is based on a combination of partial separation of variables and finite difference techniques. It has wide zene of computational freqtcency, high accuracy and good stability. For examining the efficiencg of this method,numerical results of a multilayered media model are given.

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A NUMERICAL SIMULATION FOR HYDRO-THERMAL BEHAVIOR OF THE COOLING WATER SYSTEM FOR THE THERMAL POWER PLANT IN TIDAL RIVER Wu Jiang-hang, Han Qing-shu, Zhang Ji-chun, Li Ping-heng 1987, 4(1): 35-45.  Abstract ( )   PDF (572KB) ( )   In this paper a numerical simulation for intake water temperature and aquatic environment temperature field of cooling water system for the thermal power plant under the action of tide motion by using the hybrid method of fractional steps with L∞-stability[5] is given, and its hydro-thermal behavior and environment pollution are predicted. The computed elevation of water and velocity field are in good agreement with the prototype observations, and the average intake water temperature and aquatic environment temperature distribution are also in consistent very well with the laboratory experiments.

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PRTMARY CURRENT OF TWO DIMEMSIONAL SYSTEM-GENERATED ELECTROMAGNETIC PULSE COMPUTED BY METHOD OF PARTICLE SOURCE Wang Yu-zhi, Wang Tai-chun 1987, 4(1): 46-52.  Abstract ( )   PDF (356KB) ( )   In this paper,primary current of two-dimensional SGEMP are soluted by method of particle Source.Under the same conditions that Maxwell equations, enerrgy and velocity equation of second electrons,and other computational conditions are the same as those of referenced[1].Results of qrimary current and SGEMP coincide with those of referenced[1].

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EFFECTS OF WALL TEMPERATURE ON HEAT FLUX, DRAG AND FORESTAGNATION-POINT PRESSURE OF A CYLINDER IN A THERMAL PLASMA CROSS-FLOW Chen Xi 1987, 4(1): 53-61.  Abstract ( )   PDF (588KB) ( )   This paper is concerned with the effect of wall-temperature on heat transfer,drag and fore-stagnation-point pressure of a cylinder as it is immersed.into-a thermal plasma cross-flow. Within the wall temperature region from 1000 to 3000K, the 2-D governing equations including actual argon plasma properties are solved numerically by using the SIMPLER, algorithm. Computational results show that the wall temperature has only little effect on the heat flux, the drag and the fore-stagnation-point pressure, although gas properties as well as temperature and velocity gradients at the yclinder sur-face vary significantly.

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CALCULATION OF THE THERMAL NEUTRON SCATTRING LAW FOR THE ANISOTROPIC MICROCRYSTAL Hu Yong-Ming 1987, 4(1): 62-70.  Abstract ( )   PDF (484KB) ( )   A formula for calculation of the thermal neutron scattering law for the anisotropic microcrystal which is based on Fourier transform is derived in the paper. A formula for calculation of Debye-Waller factor is derived,too.The analyses for calcuated results of anisotropic graphite are presented. It is shown that the method is effective and it is necessary to take the co-rrect value of Debye-waller. factor.

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MULTIGRID-SIP TECHNIQUE APPLIED TO TRANSONIC CASCADE FLOW USING STREAM FUNCTION EQUATION Wang Bao-Guo 1987, 4(1): 71-78.  Abstract ( )   PDF (501KB) ( )   The transonic stream function equation in strong conservation form is solved on a body-fitted coordinate system using Stone's strongly implicite-relaxation procedure enhanced by the FAS(Full Approximation Storage) alg-orithm of the multi-grid technique. As an application of such a Multigrid Strongly Implicit procedure, numerical solutions for transonic flow past sveral cascades have been computed, with satisfactory results.

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A SIMPLE CONSERVATIVE DIFFERENCE SCHEME FOR SOLVING FULL EULER EQUATIONS Wang Hong-Yun 1987, 4(1): 79-84.  Abstract ( )   PDF (286KB) ( )   We Propose here both first and second order explicit conservative difference schemes to solve1-D unsteady full Euler equations.As comPared with early schemes like MacCormack[1] etc., these proposed schemes can prevent the occurence of nonphysical expansion shock and oscillation while the computing time is increased only a little bit.A series of numerical tests shows satisfactory qualities of these schemes.

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NUMERICAL SOLUTION TO POINT SOURCE BLAST IN AIR-GRID REFINEMENT AND CORRECTION Wu Song-ping 1987, 4(1): 85-92.  Abstract ( )   PDF (386KB) ( )   An adaptive grid algorithm for the computation of the problem of point source blast in air is proposed. In the algorithm, the refined subgrids are created adaptively in response to the estimated local.truncation error of the solution. The solution on the refined grids is used to correct the original solution on the coarse grids. Numerical computation demonstrates that the propsed algorithm is efficient.

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NUMERICAL SOLUTION TO POINT SOURCE BLAST IN AIR WITH LOCAL GRID REFINEMENT Wu Song-ping 1987, 4(1): 93-101.  Abstract ( )   PDF (381KB) ( )   In this paper, the problem of point source blast in air is computed numerically with a. TVD scheme proposed by A, Harten[1]. During the computation, a grid hierarchy is introduced. The grids at different levels in the hierarchy are adjusted adaptively according to the distribution of pressure. Then,the computation marches to the next time step on the adjusted. grids. Numerical computation demonstrates the accuracy and efficiency of the proposed algorithm.

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THE CALCULATION OF MULTI-SCATTERING & FLUX-DECAY CORRECTIVE FACTOR OF FAST NEUTRON IN THE SAMPLE BY MONTE CARLO He Jin-sheng 1987, 4(1): 102-112.  Abstract ( )   PDF (628KB) ( )   When the neutron radioactive capture cross section and the. inelastic scattering cross section ((n,γ), (n,n')) are measured, the neutron flux in the sample isn't equal everywhere due to neutron multiscattering and sel-fabsorption in the finite sample.In the early work, it's supposed that neutron f lux in the sample is equal everywhere in the data processing which brings some uncertainties to the experimental values of (n,γ) and (n,n') cross section.Although it has been tested and verified by experiments that these two kind of effects can be roughly compensated each other in the special geometric sample,in order to get more accurate results, it is necessary to calculate these effects,Present work is to calculate the correction factor for the fast neutron multiscattering and self-absorption in the sample with Monte Carlo simulation method. In the real mathematical processing with Monte Carlo, because geometric size of the sample is more small in general, the forcecollision method is used in the transport procedure.To treat the collision procedure, the weighting process for scattering is adopted.Both expectation estimation method and path-length estimation method are used to record the flux distribution. We calculated the correction factor for 14 MeV neutron multiscattering and self-absorption by 56Fe.The results are in accord with experiment an-alyses.

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NUMERICAL SOLUTION OF THE SHRODINGER EQUATION FOR STATIONARY BOND STATES USING NODEL THEOREM Chen Zhi-jiang, Din-Yi-bin, Kong Fan-mei 1987, 4(1): 113-120.  Abstract ( )   PDF (468KB) ( )   An iterative procedure for getting the numerical solution of Schrod-inger equation on stationary bond states is introduced. The theoretical foundation, the practical steps and the details of the method are presented. An example calculated is added at end. Comparing with other methods, this one requires less storage, less running time but posesses higher, accuracy. It can be run on personal computer or microcomputer with 256K internal memory and 16 bit word lenght such as IBM/PC, MC68000/83/20, PDP11/23 etc.