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25 September 1995, Volume 12 Issue 3 Previous Issue    Next Issue

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THE FINITE ELEMENT METHOD FOR SOLVING THE PROBLEM OF NATURALLY FRACTURED RESERVOIR WITH TWO INTERSECTION BOUNDARIES AND ITS CONVERGENCE Liu Xiaoqing, Wu Shengchang, Hu Chengxian, Zhang Ning 1995, 12(3): 289-294.  Abstract ( )   PDF (333KB) ( )   In this paper, the well-testing analysis is made, based on the finite element method, for a naturally fractured reservoir with two intersection boundaries. Covergence of the numerical solution is proved and some typical theoretical curves of the pressure are presented in the cases of different location of the well position, different types of boundary conditions, and different intersection angles of the boundaries.

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AN APPROACH TO SOLVE A KIND OF INVERSE PROBLEM IN R3 Ma Yichen, Wei Shujun, Song Xinjuan, Liu Qisheng 1995, 12(3): 295-300.  Abstract ( )   PDF (358KB) ( )   In this paper an inverse problem is intrnduced, which determined the shape of the unknown region D in R3 nonhomogenous geoelectrical domain Ω with point sources. The existence of such problem is proved by sobolev theory. A new approach is given, which is based on a variational princible combined with an application of graphic theory. According this method, the numerical results are given. They show that this approach is feasible and effective. It can be also applied to solve other kind of inverse problem.

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NUMERICAL SIMULATION OF THE THERMAL-MECHANICAL EFFECT ON MATERIAL BOMBARDED BY ELECTRO-BEAM Zhou Nan, Ding Sheng 1995, 12(3): 301-308.  Abstract ( )   PDF (474KB) ( )   Electron transpart characteristics and energy deposition in the medium are calculated by using Monte-Carlo method. Based on the calculations thermal-mechanical effect on material bombarded by electro-beam can be investigated by solving the coupled fluid-plastic equations. Several numerical simulations of the effect in Al have been carried out as illustration of the present method. Calculated results coincide satisfactorily with the experimental data.

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EXAFS STUDIES OF THE Pr DOPED YBCO SYSTEM Han Jihong, Gu Changxin 1995, 12(3): 309-314.  Abstract ( )   PDF (419KB) ( )   EXAFS analyses of YBCO doped with Pr approve that the O position in this system changes with the Pr concentration x. With increasing x, the deformation of CuO2 plane greater, the O in the Cu-O chain nearer CuO2 plane, the distance between Ba and O3 longer. All these tructure changes in the Y1-xPrxBa2Cu3O7-δ system make the carrier density decreas and make the carrier strongly localize, which causes the change of superconductivity.

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STOPPING POWER FOR INELASTIC SCATTERING OF LOW-ENERGY ELECTRON Tan Zhenyu, He Yancai 1995, 12(3): 315-319.  Abstract ( )   PDF (318KB) ( )   Elastic scattering of Low-energy electron in solids is discribed with Mott cross-section, and a simplified calculation method on shell electron excitation is proposed.Monte Catlo simulation of low-energy electron scattering in Al, Cu, An have been proposed, the calculated backscattered coefficients, transmission coefficients are in good agreement with experiment results. Therefore, the stopping Power for low-energy electron are determined and comPared with results by Love, Rao-Sahib Wittry and Joy's modified Bethe equation.

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STABILITY STUDY OF THE METAL A1 BY THE MODIFIED-EMBEDDED-ATOM METHOD Nie Xi Liang, Wang Renhui, Ye Yiying, Yin Jian 1995, 12(3): 320-324.  Abstract ( )   PDF (298KB) ( )   The cohesive energy, stack fault energy and examined it's stability have been calculated by the means of the EAM and the ME AM in the present paper. The calculated results are in good agreement with the existing experimental results and calculated results. According to the works, the authors consider that the atomic electron density is a superposition of outer electron density of all free atoms, instead of the analytical fit in the MEAM.

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THE APPLICATION OF SIMULATION OF PEBBLE FLOW IN REACTOR PHYSICS FOR HTR Zhong Wenfa, Jing Xingqing, Luo Jingyu, Li Shilin 1995, 12(3): 325-329.  Abstract ( )   PDF (351KB) ( )   A calculational method is presented about the simulation of flow pattern of fuel elements in the physics calculation for Pebble Bed HTR. Then detailed calculation on 10MW HTR is described along with comparison of its results with that of a simplified computation without close simulation of the flow pattern of fuel elements in the reactor core.

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STUDY ON OUTPUT CHARACTER OF NONLINEAR OPTICAL FILM Jin Mingde 1995, 12(3): 330-334.  Abstract ( )   PDF (306KB) ( )   Optical output character of one-layer and two-layer nonlinear optical film andayased by numeric method is given to indicate that:the material nonlinearity has a great influence upon optical ouput character; the lower bistability threshold value light intensity and character of amplifing light intensity are chained by chosen suitable two-layer strcuture; otherwise, adjusting the distance between two nonlinear optical films and collimation of input light can improve the optical bistability output character.

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OPTCIAL FIELD CHAOS IN FREE-ELECTRON LASERS WITH A PULSED GAIN MODULATION Wang Wenjie, Wang Guarui, Chen Shigang 1995, 12(3): 335-340.  Abstract ( )   PDF (360KB) ( )   The problem of optical field chaos in a storage ring free-electron laser oscillator has been discussed by using a phenomenal model. From the theoritical analysis and numerical simulation, it can be found that the chaotic transition of the system via perioddoubling bifurcation still exists when there is a pulsed gain modulation, instead of an oscillated one, in the optical cavity. The existence of optical field chaos has been confirmed by calculating the corresponding value of the leading Lyapunov characteristic exponent. A further research shows that the real form of gain modulation in the optical cavity is most likely a pulsed one, not an oscillated one.

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NUMERICAL SOLUTIONS OF RIEMANN PROBLEMS IN THREE-PIECES FOR 2-D GAS DYNAMICS SYSTEMS (Ⅰ) ONLY CONTAIN CONTACT DISCONTINUITIES Yang Shuli 1995, 12(3): 341-348.  Abstract ( )   PDF (1610KB) ( )   Riemann problems in three-pieces, which only contains contact discontinuities on initial data, are dassified for 2-D gas dynamics systems, and numerical solutions of the Riemann problems are presented by using Taylor-FVM MInB difference schemes derived in [1].From the numerical results, it is shown that Riemann problem in three-pleas is the simplest cases in Riernann problems for 2-D gas dynamics systems, and the solution structure is basic one.

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A NEW VERSION OF THE GENERALIZED PULSE-SPECTRUM TECHNIQUE AND ITS APPLICATION Han bo, Zhang Melling, Liu Jiagi, Tang Yongfu 1995, 12(3): 349-354.  Abstract ( )   PDF (326KB) ( )   This paper presents a new version of the generalized pulse-spectrum technique,which is popularly used for solving the inverse problem of differential equations. This version has the property of immunizing noises. The skill of aving computing time is also given in the process of choosing regularign parameters. In the end, the application on the inverse problem is seismic prospection is discussed, the numerical result of simulation is given.

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GE METHODS FOR THE CONVECTION EQUATIONS Lu Jinfu, Xiao Shijiang 1995, 12(3): 355-362.  Abstract ( )   PDF (400KB) ( )   A class GE (group explicit) methods for the convection equation based on explicit or implicit upwind schemes are presented. Consistency and (weakly) stability of numerical solutions are proved. Some numerical results illustrating the methods are given.

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A STUDY OF MOVING OBLIQUE SHOCK DIFFRACTION OVER A WAVY WALL Cat Hanlong, Li Suxun 1995, 12(3): 363-368.  Abstract ( )   PDF (403KB) ( )   A new shock wave reflection phenomenon-moving oblique shock diffrection obstacle is investigated. The computation results of normal shock reflection on a wedge is compared with experimental results. Simulation results are given as well for unsteady flow field of moning oblique shock wave diffraction over a wavy wall. A flow field pattern, that's induced by multi shock interaction of oblique shock reflection, is displayed.

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IMPROVEMENTS OF TWO-DIMENSIONAL VORTEX METHOD Tong Binggang, Ma Huiyang, Yin Xueynan 1995, 12(3): 369-374.  Abstract ( )   PDF (391KB) ( )   The present paper investigates the problems of improving the numerical accuracy and the long-time computation for two-dimensional vortex methods, which are used to simulate the time-developing process of a unsteady separated flow.

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COUPLING TRANSPORT-DIFFUSION METHOD OF CALCULATING RADIATION TRANSFER IN A CAVITY Feng Tinggui 1995, 12(3): 375-382.  Abstract ( )   PDF (448KB) ( )   On the basis of characteristics of radiation transfer in the cavity, the author discussed the necessity and feasibility of calculating strategy which is to solve transport equation in the cavity and solve diffusion equation in the cavity wall. A method which links interface calculation of the two regions is presented.some numerical test results are also also given with corresponding conclusions.

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NUMERICAL CALCULATION OF NONLINEAR PROBLEM OF HIGH ENERGY LASER PROPAGATION IN THE ATMOSPHERE Let Guangyu 1995, 12(3): 383-389.  Abstract ( )   PDF (384KB) ( )   Algorithm research on numerical simulation of nonlinear problem for high energy laser propagation in the atmosphere has been curried out. The fast Fourier transform algorithm and splitting method are used to carry out theoretical analysis and numerical contrasting calculation. Both methods have second order accuracy. The calculational stability of splitting method is better and the operation is faster.

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AB INITIO-MORSE FUNCTION STUDY ON INNER-SPHERE REORGANIZATION ENERGY OF MOLECULE AB IN GASEOUS ELECTRON TRANSFER PROCESS Bu Yuxiang, Song Xinyu, Wang Yi 1995, 12(3): 390-396.  Abstract ( )   PDF (441KB) ( )   The inner-sphere reorganization energies (REs) of diatondc molecules in gaseous phase electron transfer (ET)process have been calculated in terms of Morse function scale model presented in this paper, the struCtural reorganization index (activated radius of the reduCed molecule) is given, the parameters involved can be determined via ah initio calculations at HFSCF levels (6-31G, 6-31G*, DZ and DZP (d)), The inner-sphere RE values are calibrated by comparing molecular structural parameters (bond dissociation energies, force constants) with experimental data. Results indicate that ah initio calculation values are better agreement with experimental ones, and are found to be accurate to within + l.5kcal/mol or better. This method not only improves classical model but also gets around the difficulties in obtaining available experimental data and constitutes an accurate ah initio method in calculating inner-sphere REs of diatondc molecules in gaseous ET process.

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THE SIMULATION OF STM SPECTRA OF Au (110)2×1, 3×1 RECONSTRUCTED SURFACES Huang Xintang, Qi Xiangrong, Qi Shouren, Gan Zhongwei 1995, 12(3): 397-400.  Abstract ( )   PDF (246KB) ( )   Appling the new programme on treating STM images with the method of exciton dynamics, we simulated the STM spectra of An (110)2×1, 3×1 reconstructed surfaces under the condition of single adsorbated group state, and the results are in excellent agreement with the experiments.

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APPROXIMATE EXPRESSION FOR ESCAPE PROBABILITY IN A CYLINDRICALLY EXPANDING MEDIUM Lan Ke, Zhang Yuquan 1995, 12(3): 401-406.  Abstract ( )   PDF (362KB) ( )   An approximate expression for escape probability for Doppler Profile lines in a cylindrically expanding medium is obtained in this paper. The complicated quintuple integral griving escape probability is approximated by a simple integral which has a Gauss-shaped integrand. The largest error is no more than 7%.

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A NUMERICAL SOLUTION OF CONSTANT WELLBORE PRESSURE WITH VERTICAL FRACTURE Cai Yuehong, Cai Zongxi, Zhang Qinghe 1995, 12(3): 407-414.  Abstract ( )   PDF (476KB) ( )   The hydraulic fracturing are widely used in oil field as a good means of the exploit of low permeability oilgas reservoir and the output increase of oil field. To make the hydraulic fracturing scheme economic, reasonable, and improved, a numerical solution is given to the mathematic model of predicting the hydraulic fracturing oil's output on condition of constant wellbored Pressure production of oil-gas reservoir. The various conditions and elements needed to be considered for the model are described. It provides an overview on the numerical solution of nonlinear parabolic oil-gas reservoir equations with the fracture in the area and the coefficient depending on the unknown function.

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THE REGULARIZATION METHODS FOR SOLVING INVERSE PROBLEM OF ONE-DIMENSIONAL WAVE EQUATION Wu Jiancheng, ZhangDali, Liu Jiaqi 1995, 12(3): 415-420.  Abstract ( )   PDF (316KB) ( )   Under the general initial-boundary-value condition and additional condition, the methods for solving problem of one-dimensional wave equation is discussed. The inverse problem is reduced to an ill-posed non-linear integral system. Tikhonov's regularization method overcomes the difficulty of inverse problem and has a good numerical stability. The Numerical results show that the method is feasible and effective.

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A FINITE DIFFERENCE SCHEMES FOR A CLASS OF SYSTEMOF GENERALIZED NONLINEAR SCHRODINGEREQUATION OF HIGH ORDER Zeng Wenping 1995, 12(3): 421-425.  Abstract ( )   PDF (284KB) ( )   The paper discusses a class of system of generalized nonlinear schr.dinger equation of high order. A leap-frog finite difference scheme and mixing crank-Nicolson and leap frog finite difference scheme are givent and convergence and stability are also proved. As an example, a given numerical result confoums to the analytically exact one.

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RESEARCH THE NUMERICAL METHODS OF CALCULATING THE TRIODE SYSTEM OF ELECTRON GUN Let Wei, Tong Linsu, Yang Hut 1995, 12(3): 426-432.  Abstract ( )   PDF (406KB) ( )   There are two methods to calculate the triode system of electron gun:First method is Continuous Emitting method, it regards the cathode emitting as a continuous action, so it can only calculate a few of electron trajectories, and takes short time. Because it calculates a continuous cathode emitting, the error of calculation is big. The second method is Monte Carlo method, it calculates the cathode emitting with random method, and then calculates many random electron trajectories. The error of this method is smaller than Continuous Emitting method, but it will take a lot of time. This paper discusses a new method, it regards the cathode emitting as a continuous action when the value of electric field is not very precise, then it uses Monte Carlo method to calculate triode system when the value of electric field is precise. This new method decreases the error of calculation and saves time of computation.