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25 March 1985, Volume 2 Issue 1 Previous Issue    Next Issue

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MONOTONE QUADRATIC SPLINE INTERPOLTIONAND ITS APPLICATIONS TO THE CONMPU-TATION OF STATE EQUATIONS Zhang Bao-Lin 1985, 2(1): 1-7.  Abstract ( )   PDF (416KB) ( )   This note proues the following result. Let a, b, ya, yb, ya', yb'be real numbers satisfying aab;ya'≥0,yb'≥0;ya'+yb'≤4((yb-ya/(b-a))) then the mo-notone increasing quadratic spline S(x)∈C1[a,b]with knots at a,(a+b)/(2), b existsand is unique, and if ya'+yb'4((yb-ya)/(b-a)), such quadratic interpolating spline do-es not exist.According to this result the paper studies the existence of monotone cuadratic interpolating splines with more knots, and gives a computational method of smoothly Linking up the energy and pressure surfaces between different regions of state equations.

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A NUMERICAL METHOD FOR INVERSE PROBLEM OF PLASMA EQUILIBRIUM Feng Gui-Yun 1985, 2(1): 8-16.  Abstract ( )   PDF (650KB) ( )   The present paper aims at setting up a stable numerical method for the inverse problem with noncircular cross-section plasma equilibrium. BY means of a discretization operator, the filtering is applied to determine the external solution for the inverse problem. In the paper, an effective explicit step by step filtering algorithm for numerical calculation is also presented and some of results obtained by this technique for noncircular cross-saction plasma is given.The numerical solution is compared with the analytic one in the case of circular cross-section plasma.

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A MONTE CARLO SIMULATION METHOD OF ELECTRON INTERACTIONS WITH SOLIDS He Yen-cai 1985, 2(1): 17-23.  Abstract ( )   PDF (481KB) ( )   A physics model for describing electron interactions with solids and its Monte Carlo simulation method are proposed. Its calculation process is simpler. The e-valuated results for the backscatter coefficient, the transmission coefficient and the distribution function in depth of X-rays based on the model are in agreemet with the published expeimental facts.The model has been successfully applied to the X-ray quantitative analysis of thin films and microparticles.

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NUMERICAL SIMULATION METHOD FOR TRANSPORT CHARACTERISTICS OF INTENSE ION BEAMS IN ACCELERATION-DECELERATION SYSTEM Hua Da-ping, Fang Jin-qing 1985, 2(1): 24-37.  Abstract ( )   PDF (926KB) ( )   In this paper, a convergent two-dimensional numerical simulation method for transport characteristics of intense ion beams in acceleration-deceleration system is presented.Our problem requires the simultaneous solution of:(1) the nonlinear Poisson's equation, (2)tne non-relativistic equation of ion motion; (3)the con-tintity of ion current. Because of the complexity of the boundary geometries, finite element method is used to solve Eq.(1)And the computer program was developed. The self-consistent results of space potential distribution, ion trajectories and distribution of ion space charg density are given. The method is suitable to study transport problem of intense ion beams in acceleration -deceleration system, in particular, for high intensity ion implantation facility, intense ion beamsexten-sion, intense plasma ion source and so on.

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POSITIVE CONFRIBUTON MONTE CARLO METHOD FOR SOURCE CONVEX REGION Pei Lu-cheng 1985, 2(1): 38-46.  Abstract ( )   PDF (611KB) ( )   The contribution of more secondaries particles in the contributon Monte Carlo method by Dubi and Gerstl is negative[3,10]. The negatively contributing particle often makes the statistical fluctuation, of the Monte Carlo estimate become large and the computation is more time-consuming. Therefore, if is Very necessary to solve the negatively contributing problem of the secondery particleIn this paper, a new contributon Monte Carlo method called the SCR qositi-ve contributon method is proposed. In any case, the SCR positive contributon method is surely betfer than the contribufon method by Dubi and Gerstl hence the former can replace the latter thorughly, too. The negativily contributing prob-lem of the secondary particle for tho source convex region is solved, The results of the practical calculation by examples indicates that the efficiency of the present method can be raised by 1.5 of 3.4 times in comparison with the method by Dubi and Gerstl.

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NUMERICAL CALCULATION OF ATTRACTOR DIMENSIONS Wang Guang-rui, Chen Shi-gang, Hao Bai-lin 1985, 2(1): 47-54.  Abstract ( )   PDF (554KB) ( )   We calculated the attractor dimensions of the forced Brusselator in autonomous form using the Poincare section method in order to reduce the dimension of the phase space concerned by one.This enables the computation of Kolmogoroff capacity dc with limited storage and facilitates the calculation of the Lyapunov dimension dL · In calculating do we used a cell-merging scheme to get a set of N (ε) correspoonding to different ε, s, while the differential equations were being solved only once for a given set of parameter values Both computer time and stora-gewere saved in this way. In theis paper we makeemphasis on the thechnical subtleties encountered in numerical calculation.

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NUMERICAL MODELING OF DIVERGENT DETONATION WAVE Li Zhi-wei, Liu Bang-di 1985, 2(1): 55-66.  Abstract ( )   PDF (783KB) ( )   In this artical a unsteady nature of divergent detonation wave has been briefly describees with the assumption of instantaneous steady detonation. In the method for numerical modeling of divergent detonation we have improved artificial stickiness and described ignition process of explosive with cochran's reaction rate and JWL equation of state. A few of typal divergent detonation problems have been Calculated with our 2DL program and Some satisfactory results have been been gotten.

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A DATA ANALYSIS METHOD FOR EXAFS Wang Xi-chuan 1985, 2(1): 67-75.  Abstract ( )   PDF (690KB) ( )   In the present paper the data analysis for EXAFS (extended x-ray absorption fine structure),starting from the treatment of the raw data to the extraction of the structural information has been described. The background subtraction, Fourier filtering, and the choice of the threshold energy were discussed. Furthermore, the curve-fitting method was given for the improvement of accuracy, Using the method various samples (Cu, CuNi and CuNiMn) were studied,and the results obtained were quite satisfactory.

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THE NUMARICAL SOLUTON OF NEUTRON MODERATING LNTEGRAL EQUATION Hu Li-qing, Chen Wen-tao 1985, 2(1): 76-82.  Abstract ( )   PDF (430KB) ( )   For multi-region co-centre cylinder cell the numaricll solution of neutron moderating integral equation is a approximate solution using Lobatto quatrature formula. It can get more accurate epithermal energy spectrum, therefore resonance integral, group cross-section and self-shielding factor of resonance as well.Using the method of step by step recurrece to calculate moderating souece and the premade table of Pij to interpolate collision probability, a great deal of computing time could be saved. In this paper resonance cross-section for 235U, 239Pu were calculated using multi-level formula so as to consider interference and overlap ping effect between resonances.A check calculation has been made based on the model provided by Ref.[7]and the both results agree well eath other.

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EIGENVALUES OF MATRIX PENCIL AND A PROGRAM FOR ANALYSING THE STABILITY OF LINEAR REGULATORY SYSTEMS Dong Hao-zhe 1985, 2(1): 83-90.  Abstract ( )   PDF (541KB) ( )   Since the Problem of analysing the stability of a linear regulatory system c-anbe transformeal into the problem of solving the eigenvalues of a matrix. pencil of the type λB-A, it is suggested in this paper to solve the eigenvalue problem by the QZ method A computer program is proposed, which gives not only the eige-nvalues but also the matries that transform the matrix pencil into upper triangular form.

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THE GENERALIZED LINDEMANN MELTING LAW Zhang Shi-ze, Zhang Wan-xiang 1985, 2(1): 91-98.  Abstract ( )   PDF (496KB) ( )   In this paper we have extend Lindemann melting theory to the anharmonic oscillator solids and derived a generalized Lindemann melting law.The melting curve for Fe, Cu, Al are calculated and satisfactory agreement with experiments is obtained.

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THE NUMERICAL SIMULATION OF EARIY STAGEOF VISCOUS INCOMPRESSIBLE FLUID FLOWAROUND A CIRCULAR CYLINDER Lu Jian-Qun 1985, 2(1): 99-108.  Abstract ( )   PDF (607KB) ( )   The simulation of incompressible fluid past a circular cylinder of diameter D at moderate Reynolds number on the basis of full unsteady Nnvier-Stokes equation is accomplished by a new method described in this paper. The cylinder is started impulsively with a constant velocity. Reynolds number(Re=U∞D/v)was chosen as 200,550 and 3000 respectively. We obtained numerically the non-steady flow near cylinder and the formation of isolated secondary eddy and secondary eddy pair. Furthermore, the numerical results are agreement with recent experimental results. The method presented here is a sequel to elliptic-vortex method prese nted-by Zhen-huan Teng in [1]. In the paper we allow the change of shape of vortices from ellipic as it locates near cylinder and then circular far from cylinder. We intend to simulate flow separation based on Navier-Stoke equation instead of P-rantl's equation. The fulfillment of boundary condition on the surface of the cyli-nder is crucial. We compare various reasonable numerical treatment of this kind of boundary condition, and present in detail the best one.

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ON THE APPLICATION OF ALTERNATING DIRECTION METHODS TO COMPUTATIONS OF WATER TABLE FLOW Lei Guang-yao, Zhang Suo-chun, Gao Ji 1985, 2(1): 109-115.  Abstract ( )   PDF (532KB) ( )   For saturated-unsaturated water table flow, computations of ADEP, ADIP and implicitly alternating direction iterative procedure are made and compared.The i-terations are not convergent and computational results are strongly distortional Based on supplementing a particular term, a kind of completely implicit and altern-ting direction iterative procedure is given The relative results for computational model of different scales are satisfactory. Problems of how to give the particular supplemental term and how to select better parameters are discussed, the computational results are given.

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THE SIMPLIFICATION AND CALCULATION OF A 15-FOLD INTEGRAL IN NUCLEAR MATTER THEORY Shen Qing-biao, Zhang Jing-shang 1985, 2(1): 116-123.  Abstract ( )   PDF (442KB) ( )   A 15-fold integral over 5 momentum vectors which appears in nuclear matter theory and is subjected to the Pauli principle is discussed. The 15-fold integral is reduced to a 5-fold one due to the energy and momentum conservation and by choosing proper integration variables and the coordinate system. The number theory mesh method is used in the numerical calculations. The calculated results are given in tabular form for very wide range.

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COLLISION BETWEEN SOLITONS——collision between solitons of nonliner Shrödinger equation with extenal field Wang Hung-ying 1985, 2(1): 124-127.  Abstract ( )   PDF (209KB) ( )   In this paper, we investigate collisions between two solitons of nonliner Shro-dinger equation with extenal field. We find that the two solitons with variable velocity can emerge again after collision.