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25 March 1990, Volume 7 Issue 1 Previous Issue    Next Issue

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THE LUMPED MASS FINITE ELEMENT METHOD FOR TWO-DIMENSIONAL SHALLOW WATER WAVE PROBLEM Wu Ketian 1990, 7(1): 1-6.  Abstract ( )   PDF (326KB) ( )   The lumped mass finite element method for two-dimensional unsteady flow is introduced. This method and the method in[1] are used in calculating the flow velocities and tide for the north branch of Yangtze River.The numerical result shows that the lumped mass finite element melhod need much less time and memory than the method[1] and retain previous accuracy.

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MONTE CARLO SIMULATION OF SU (2) GLUEBALL MASSES ON AN ASYMMETRIC LATTICE FOR COUPLING LESS THAN ONE Dong Shaojing, Ying Heping 1990, 7(1): 7-10.  Abstract ( )   PDF (248KB) ( )   A Monce Carlo Calculation of SU (2) glueball masses on an 53×30 asymmetric lattice for β=4.3 is performed. The fine-grained data told us, within error 20%, M(2+)≈M(0+). The Higher excited states are also estimated. The results are M(0+)/M(0+)=2.6±0.3 and M(2+)/M(2+)=2.9±0.4.

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SOLITARY WAVE SOLUTION OF INITIAL-BOUNDARY VALUE PROBLEM OF BOUSSINESQ EQUATION Lu Qiouqiang 1990, 7(1): 11-16.  Abstract ( )   PDF (354KB) ( )   A finite-difference Scheme for the Boussinesq equation and the calculation of the initial-boundary value problem of Boussinesq equation are carried out. Those results show the enistance of solitary wave solution.

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A SOLUTION OF TEMPERATURE DISTRIBUTIONS FOR THE PULSE-MAGNETRON USING THE INTEGRAL METHOD Zhang Yaoxian 1990, 7(1): 17-23.  Abstract ( )   PDF (397KB) ( )   The numerical methods are suggested in solving the temperature distribution of the pulse-magnetron. The governing equation of the temperature field of pulse-magnetron is a nonlinear second order partial differential equation.Its solution is found by using the integral method.

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PARTICLE SIMULAION FOR ELECTROSTATIC OSCILLATION OF VIRYUAL CATHODE IN RELATIVISTIC ELECTRON BEAMS Chen Deming, Wang Min 1990, 7(1): 24-30.  Abstract ( )   PDF (409KB) ( )   The virtual cathode oscillation in relativistic electron beams is studied by a 1-D electrostatic particle simulation code with the finite-size-particle model. The calculation results show following conclusions; When injection current is less than the space charge limiting current, cicctron beam propagates stably and transsmits completely. When injection current exceeds the space charge limit, ils propagation is unstable, a part of electrons reflect and the other electrons transsmit. The position and potential of the virtual cathode caused by space charge effects oscillate periodically. When the beam current increases, the virtual cathode position is closer to the injection plane and its oscillating region gets narrower, the virtual cathode potential decreases and its amplitude increases, the oscillation frequency increases above the beam plasma frequency.

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A NEW METHOD TO GENERATE THE BODY-FITTED COORDINATE SYSTEM FOR THE CHANNELS OF A CENTRIFUGAL IMPELLER WITH TWISTED BLADES Xi Guang, Wang Shangjin, Maio Youngmaio 1990, 7(1): 31-38.  Abstract ( )   PDF (482KB) ( )   A new method to generate 3-D body-fitted coordinate system for the channels of centrifugal impellers was described. The coordinate system is generated by solving a number of 2-D elliptical partial differential equations. Comparing with the method directly solving three 3-D elliptical partial differential equations for body-fitted coordinate systems, this method can save much computer time and storage. An example of coordinate generation for a centrifugal compressor impeller was given.

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LU IMPLICIT SCHEMES WITH FAS-MULTIPLE GRIDS FOR THE EULER EQUATIONS Gao Shuchun, Wang Baoguo 1990, 7(1): 39-44.  Abstract ( )   PDF (350KB) ( )   A lower-upper implicit scheme is developed for the unsteady Euler equations. The scheme requires only two sweeps through the grid and it is unconditionally stable. Each factor represents an algebraic system which is either lower block diagonal or upperblock diagonal and hence the name LU. Inversion of such systems is relatively simple and efficient. A nonlinear multigrid algorithm,full approximation storage (FAS),is combined with LU implicit scheme to produce a rapidlyconvergent algorithm for calculating steady-state solutions of the Euler equations.

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A METHOD OF IMPROVING THE COVERGENCE RATE OF DV-α-SCC CLUSTER CALCULATION Pan Wei, Zheng Qingqi 1990, 7(1): 45-49.  Abstract ( )   PDF (307KB) ( )   A method of improving the convergence in the DV-α-SCC calculation are studied in the scheme suggested by Broyden. The obtained result reveals that the convegence of SCC calculations is greatly accelerated by our new calculation procedure. This method may improve the problem of relative slow convergence or even non convegent which are usually happened in the DV-α-SCC calculations for large cluster with low symmetry.

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COMPARISON AND ANALYSIS OF FREE ELECTRON LASER AMPLIFIER NUMERICAL RESULTS COMPUTED BY WAGFEL AND FBC CODE Wang Taichun, Yang Zhenhua, Tian Shihong, Dong Zhiwei 1990, 7(1): 50-60.  Abstract ( )   PDF (679KB) ( )   In this paper, the equations of FEL amplifier with aplanar wiggler are derived. FBC code based on equations is designed by H.P.Freund. WAGFEL code based on KMR theory are designed by us. Although there are obvious differences between WAGFEL and FBC code, in dealing with practical problems such as magnetic field and length of the entry wiggler, initial distribution of electron beam, fashon of the downstream tapered wiggler etc, a set of c-oupled nonlinear differential equations used in two codes is based on single-particle theory. Meanwhile, under the certain conditions, the computational results of both WAGFEL and FBC code coincide with those of the experiment well. Then the computional results used by WAGFEL and FBC code are compared.The results of TE01 mode calculated with WAGFEL and FBC code are compared and analyzed under the condition of the constant and varyable amplitude of wiggler magnetic field Bw, respectively. The analyzed results show that regard the conditions and results of experiment as criterion, WAGFEL code is more useful in comparing similation results with experiment than FBC code. As a result, not only data of 4MeV amplifier which are computed by WAGFEL code are valuable, but WAGFEL code is feasible to design amplifier and study problems of FEL.

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ON THE ENERGY LEVELS OF THE COMPRESSED ATOM Qiu Yanghuei, Li Shichang 1990, 7(1): 61-68.  Abstract ( )   PDF (435KB) ( )   In this paper a model of compressed atom for condensed matter is described. The atom is supposed to be enclosed in a sphere of radius R0, which is determined by the matter density. The orbital energies and the wave functions are obtained from the solutions of the Dirac equation in a self-consistent field with different boundary conditions. We find when the matter densities are small, the energy levels are just like the situation of free atom, when the matter densities are large, The energy levels are changed greatly. As an example the calculated results of compressed Iron are presented.

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THE APPLICATIONS OF REGIONAL ANALYTICAL THEORY TO THE CALCULATION FOR CRITICAL VALUE OF DAMPING RESISTOR Lai Dingwen, Wang Jian, Wang Zhengxian 1990, 7(1): 69-78.  Abstract ( )   PDF (580KB) ( )   The approximate analysis of differential systems by applying the theory of regional analysis, is described. It supplies a formularization and calculating programme for algebraic limit cycle of second degree in a type of differential systems of third degree, and also for critical value of damping resistance in power systems. This new method simplifies the traditional method, hence it is acceptable and applicable for engineers. Finally, a few of examples are given based on this method.

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STRESS CALCULATION OF TOROIDAL FIELD D-SHAPED COILS FOR THE FUSION REACTOR Jian Guangde, Shi Hanwen 1990, 7(1): 79-84.  Abstract ( )   PDF (335KB) ( )   The stress distribution of toroidal field D-shaped coils for the TOKMAK fusion reactor is solved by the finite element method. It has been shown that the results of mechanical stress are in agreement with that of the JET toroidal field coils, the shearing stress is small along conductor, approximate to pure tension coil.

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EFFECT OF EMPTY ATOMIC SPHERES AND ATOMIC EMPTY d STATES ON THE BAND STRUCTURE IN sp3-SEMICONDUCTORS Wang Renzhi, Huang Meichun 1990, 7(1): 85-90.  Abstract ( )   PDF (400KB) ( )   The features and functions of both the empty atom-spheres and atomic empty d-states in linearized muffin tin orbital (LMTO) band structure calculations for sp3-semiconductors are investigated. A new approach, in which the states associated with atomic empty d states and empty-sphere p and d states are only incorprated in the evaluation of matrix elements is suggested. The method is spplied to study the band struture of gaAs as a test case. It is shown that the convantional secular determinant with a size of 36×36 can be reduced to a much smaller one with a aize of 10×10 and the results are still quite reasonable.

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THE INTERACTIONS OF LASER BEAM WITH HIGH Z SOLID TARGET——COMPUTATIONAL SIMULATION OF THE INTERACTIONSFOR LASER WITH PLASMA(Ⅱ) Peng Huimin, Zhang Guoping, Sheng Jiatian 1990, 7(1): 91-100.  Abstract ( )   PDF (565KB) ( )   The 1-D non-LTE radiative hydrodynamic laser irradiated code JB-19 is used to calculate the laser-produced plasma conditions of high z gold disk. Following physical processes are considered:bremsstrahlung effect, radiative ionization and recombination, collisional ionization by electrons and three-boby recombination, collisional excitation and de-excitation by electrons, radiative line emission and absorption and Compton scattering. A gaussian laser pulse with wavelength 1. 06μm, FWHM 600ps and peak intensity 3×1014W/cm2 is used to irradiate thickness 20μm gold disk. The computational results for laser-produced plasma conditions and the absorption efficiency and laser-x-rays conversion efficiency for gold disk are shown.

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USING PREPULSING-A USEFUL WAY FOR INCREASING ABSORPTION EFFICIENCY OF HIGH INTENSITY LASER BEAM Peng Huimin, Zhang Guoping, Sheng Jiatian 1990, 7(1): 101-107.  Abstract ( )   PDF (453KB) ( )   The efficiency of laser light energy absorbed by the coronal plasma of target is crucial to laser fusion. Using prepulse to irradiate target for increasing absorption efficiency of high intensity incident laser beam is considered and some theoretical simulations have been done. 1-D non-LTE radiative hydrodynamic code is used to simulate the interactions of laser beam with matter. The basic equations of this code are consisted of:the 1-D equations of radiative hydrodynamics, the average-atom population rate equations, the multigroup flux-limited diffusion equations for radiation transport, and the equations for deposition of laser light energy in plasma. The following physical processes are considered:the bremsstrahlung effect, radiative ionizations and recombinations, collisional ionizations by electrons and three-boby recombinations, collisional excitations and de-excitations by electrons, radiative line transitions and Compton scattering.A gaussian laser prepulse of wavelength 1.06μm, FWHM 600ps and peak intensity 1.5×1012W/cm2 was used to irradiate thickness 20μm Au plate target, after 3ns a main gaussian pulsewith wavelength 1.06μm, FWHM 600ps and peak intensity 3.0×1014W/cm2 irradiated the expanding Au plasma. The responces of laser-produced plasma conditions are shown. By comparison with without prepulsing, under the condition of same main incident laser pulse, the absorption efficiency is increased from 0.36 to 0.60 and the laser-x-ray conversion efficiency is increased from 0.16 to 0.25. The electron temperature of hot plasma is also higher than without prepulsing, and the x-ray spectrum which is emitted from laser-produced hot plasma is harder and more intense than without prepulsing. The responces of laser-produced plasma for Fe target with prepulsing are shown as well. The conclusion is that using prepulsing is useful way for getting high absorption laser beam.

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SOLITARY WAVES INDUCED BY BOUNDARY PULSE Chang Qianshun, Wang Guobin, Guo Boling 1990, 7(1): 108-114.  Abstract ( )   PDF (354KB) ( )   In this paper, We consider solitary waves induced by boundary pulses for regularized Long-wave equation. A conservative difference scheme is presented for the equation. Using the scheme, solitary waves induced by several boundary pulses are computed numerically. We explore the relationship between the amplitudes and numbers of the solitons produced and the boundary pulses, and compare solitons induced by the boundary pulse with ones produced ny initial pulses.

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THE CALCULATION OF SPIN ENERGY LEVEL AND WAVE FUNCTION OF ELECTEON FOR Cr3+IN K3[Cr(CN)6] Lin Qiaoyuan, Lu Li 1990, 7(1): 115-121.  Abstract ( )   PDF (354KB) ( )   At first under the external magnetic field H acting around the axes (x,y,z) of lattice field was the calculation of the splitting of energy level of the Cr3+in K3[Cr(CN)6] shown. Secondly, the simultaneous calculating method for the energy level and the wave function was shown under the external magnetic field H acting around the axes (a,b,c) of cryatal. It is called the simultaneous calculating method by us, that the values of energy level and wave function calculated out at the same time by the computer. The calculating process is reduced and the amount of work is decreased. And this method ensures that the perpendicular and unitary conditions of the obtained wave-function can be satisfied. This method may° be extended to the calculation of other similar-question. Finally,the values of wave function and the energy level diagrams are obtained by this method.

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A SOFTWARE FOP CALCULATING RENORMALIZATION CONSTANTS BY USING REDUCE PROGRAMMING LANGAUGE Dai Qinghai, Ma Wengan, Liu Yiaoyang 1990, 7(1): 122-126.  Abstract ( )   PDF (285KB) ( )   By defining vaccum self-energy diagrams and using REDUCE programming langauge, the calculation of renormalization constans in the weinberg-salam standard model can be performed by computer.