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25 November 1997, Volume 14 Issue 6 Previous Issue    Next Issue

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HAMILTON SYSTEM AND SYMPLECTIC ALGORITHMS FOR THE ANALYSIS OF PIEZOELECTRIC MATERIALS Zou Guiping 1997, 14(6): 735-739.  Abstract ( )   PDF (183KB) ( )   In onder to deal with coupling of elasticity and electricity,the Hamilton canonical equation for the piezoelectric materials is presented.By the separation of the whole state variables,the conesponding analytical symplectic solution is also given.

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TURBULENT CONVECTIVE MASS TRANSFER OF WATER WITH INTERNAL MASS SOURCES IN HEATED TUBES Jiang Peixue, Protopopov V S, Ren Zepei, Wang Buxuan 1997, 14(6): 740-748.  Abstract ( )   PDF (356KB) ( )   A turbulent model of convective mass transfer and a model of internal mass sources resulted by crystallization are presented. The theoretical analysis and numerical calculation are carried out for turbulent convection mass transfer in heated tubes with consi deration of internal mass sources under constant properties. The influence of internal mass sources on the concentration distribution, average concentration of colloidal particals and mass flux on the wall has been analyzed. It has been found that if the mass transfer coefficent in the case with consideration of internal mass sources is defined as Eq.(20), the Sherwood number and mass transfer coefficient in the case with consi deration of internal mass sources are equal to those in the case without consideration of internal mass sources; Under the conditions studied here, Is<<Cm, the effect of Is on mass transfer can be neglected; In the case when considering internal mass sources the mass flux may increase gradually along x due to increase of Cm.

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NUMERICAL SIMULATION FOR THERMAL EMISSION OF CATHODE Lei Wei 1997, 14(6): 749-754.  Abstract ( )   PDF (237KB) ( )   In the electron beam and ion beam device, the emission system affects the quality of the whole device. Therefore it is very important to analyse the emission system in electron beam device. This paper studies the method of numerical simulation of the electron emission. The planar diode model which is often used to calculate the emission of cathode is discussed and the error caused in the numerical simulation is analysed. On the basis of these discussions, this paper uses another method to simulate the thermal emission of cathode more precisely.

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STUDIES ON TRANSIENT RESPONSES OF MICROWAVE RESONATOR Wang Jianguo, Yu Hanqing, Chen Yusheng, Fan Ruyu, Ge Debiao 1997, 14(6): 755-759.  Abstract ( )   PDF (199KB) ( )   A nonorthogonal finite difference time domain algorithm is used to model the excitation and resonance processes of a circular resonator with an excitation aperture,where a Gaussian pulse and a sine modulated Gaussian pulse are used as excitation pulses.Resonant frequencies are analysed by the method of fast Fourier transform.The calculated results agree well with theoretical analyses.Simulation results show that several resonant frequencies nearest to the main ferquency of the excitation pulse are excited.

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NUMERICAL ALGORITHMS OF FRACTIONAL FOURIER TRANSFORMATION Liu Shutian, Sun Kaixia, Ren Hongwu 1997, 14(6): 760-764.  Abstract ( )   PDF (191KB) ( )   Two numerical algorithms of fractional Fourier transform,de chirping and Gaussian Hermite decomposition,are theroetically described.Computer simulation results and applicable situations for these two algorithms are given.

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Radiative Opacity For High Z Elements Sun Yongsheng, Yuan Jiankui, Zheng Shaotang 1997, 14(6): 765-769.  Abstract ( )   PDF (209KB) ( )   A method based on the Hartree Fock slater self consistent average atom model is employed to calculate opacities of medium and high Z materials. Comparisons with other theoretical results and experiments show that this model is reasonable.

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MODELLING THE IONIZATION POTENTIAL OF HALO ALKANES BY NEURAL NETWORK APPROACH He Liming, Bao Yushi, Lu Hui, Jin Qianyuan 1997, 14(6): 770-776.  Abstract ( )   PDF (236KB) ( )   The Back propagation(BP) model of neural network is used to calculate the first ionization potention(IP) of haloalkanes.By optimizing the neural network,the standard deviation of errors of prediction(SDEP) using leave one out method within the known samples is 0.34eV,which is better than the reported predicting and calculating results by PLS.

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NUMERICAL ANALYSES OF THE BURNING PLASMA TEMPERATURE PROFILES IN FUSION REACTORS Yu Tingyan, Shi Bingren 1997, 14(6): 777-781.  Abstract ( )   PDF (196KB) ( )   Combined with the overall energy balance equation of the background plasma,the multi energy group equations which evolve the distribution function of α particles during slowing down are employed to perform self consistent numerical investigation of the burining plasma temperature profiles of importance to fusion reactors.By simulating both the dynamic and steady state plasma operating regime,it is showed that the burning plasma temperature profiles tend to be more peaked than that of the experimentally derived profiles.Such a feature is persisted whether or not there is significant diffusion of α particles during their slowing down and should be taken into account in future rigorous analyses of the behaviors and effects of α particles in fusion reactors.

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NON-LINEAR ANALYSIS OF TV PROPERTIES OF MUSCL TYPE SCHEMES Ding Jianzhong 1997, 14(6): 782-786.  Abstract ( )   PDF (191KB) ( )   The TV properties of MUSCL type schemes for hyperbolic conservation laws are discussed.From the general form of MUSCL type schemes,the requirements to keep the schemes TVD are proposed and verified.They can be presented directly as the limitation to the sign and magnitude of the variable variations,and fully reflect the principle of region dependence of solution to hyperbolic equations,so as to provide a theoretical tool to analyze the MUSCL type schemes.The paper also presents the basic ideas on reconstruction of numerical solution distribution,based on the proposed TVD requirements,to reduce numerical dissipation and improve resolution of the contact discontinuities and head/tail of rarefaction waves.

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SIMULATION OF DISCRETE SPACE CHARGE EFFECT WITH MONTE CARLO METHOD IN THE TRANSPORTATION OF ELECTRON AND ION BEAM Lei Wei, Yin Hanchun 1997, 14(6): 787-795.  Abstract ( )   PDF (369KB) ( )   In electron beam lithography system,focus ion beam system and cathode ray tubes,the space charge effect caused by the interaction of every particle affects the quality of the device.A lot of scholars have already studied the space charge effect.As so far,Monte Carlo method is often used to calculate the space charge effect in the transportation of particles.This paper tries to use Monte Carlo method to calculate the space charge effect in the beam form region.The 'edge effect' is analysed and some new ways are proposed to decrease the'edge effect' in the simulation.

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CYCLE COUPLING ITERATION METHOD FOR EVALUATION OF SUPER LARGE ZONAL MATRIX IN THERMODYNAMIC EMULATION MOLD Ye Hong, Chou Qiaoli, Ge Xinshi, Weiwei 1997, 14(6): 796-802.  Abstract ( )   PDF (290KB) ( )   A method of mutual coupling and circulating iteration is presented to evaluate the thermal resistance and thermal capacity network of unit (differential) sections and separate joint points for the solar energy collecter system based on the model proposed by the second writer of this paper.

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BOUNDARY ELEMENT METHOD FOR SOME POTENTIAL PROBLEMS Li Weinan, Han Qingshu, Zhou Xueqiu 1997, 14(6): 803-807.  Abstract ( )   PDF (209KB) ( )   Some potential problems are studied by applying boundary element method.The starting equation in the form of discretization is obtained by weighting residual.The computer software for numerical simulation has been provided.Numerical results conform to physics law and are satisfactory.

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THE DYNAMIC RESPONSE OF ALUMINIUM ALLOY AND CARBON PHENOLIC COMPOSITE PLATE UNDER HIGHVELOCITY IMPACT Wang Yi, Xu Nanxian, Xie Yuannan, Lin Shaoming, Zhang Shize 1997, 14(6): 808-814.  Abstract ( )   PDF (450KB) ( )   The dynamic response of aluminium alloy and carbon phenolic composite plate impacted by an iron bullet has been studied by finite element method. Both the results of theoretical calculation and graphical analysis are given.

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APPLICATION OF THE COORDINATE TRANSFORMATION FOR COMPUTING WAVEGUIDE TUBE EDDY CURRENTS Wang Yuzhi, Huang Yixin, Wu Zhongfa 1997, 14(6): 815-822.  Abstract ( )   PDF (312KB) ( )   The mesh dividing in an irregular domain is very difficult for computing the pulsed guide magnetic field eddy currents. A method of coordinate transformation is proposed which mappes the irregular domain to a regular domain. In the new domain it is convenient for the dividing of meshes. By using this method some satisfied computational results are obtained.

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A STUDY ON THE CLOSURE SCHEMES COMPARISON OF ATMOSPHERIC BOUNDARY LAYER EQUATIONS Miao Manqian, Cao Hong, Tang Youhua 1997, 14(6): 823-828.  Abstract ( )   PDF (234KB) ( )   The TKE (Turbulent Kinetic Energy) closure scheme with 1(1)/(2) order precision and the method of reducing vertical layers are used to decrease computing amount. Modelling results agree well with observations. Compared with results of 3 order closure schemes, there is no obvious reduction of precision. This scheme provides the possibility of inducting and improving the precision of PBL parameterization in three dimensional atmospheric models.

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A FULLY CONSERVATIVE IMPLICIT DIFFERENCE SCHEME FOR FLUID DYNAMIC EQUATIONS Jin Hui, Chen Guangnan 1997, 14(6): 829-834.  Abstract ( )   PDF (231KB) ( )   A fully conservative implicit difference scheme for Lagrangean form of the fluid dynamic equations is presented. This new scheme not only guarantees the laws of conservation of mass, momentum and total energy, but also satisfies the balance properties of inner energy and kinetic energy. Two numerical tests are calculated by this scheme as comparied with other difference schemes.

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A NUMERICAL METHOD OF SPACE TIME CONSERVATION Zhang Zengchan, Shen Mengyu 1997, 14(6): 835-840.  Abstract ( )   PDF (228KB) ( )   The nontraditional method of space time conservation element and solution element (CE/SE), developed by chang S C in 1995, is modified. A new constructing method is used to obtain the calculating schemes. These new schemes not only have all the features which the CE/SE method has, but also are simpler, more accurate and have very high resolution of discontinuities.

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QUASI STEADY EULER CALCULATION FOR ROTORS Wang Liqun, Qiao Zhide, Zhang Ru 1997, 14(6): 841-845.  Abstract ( )   PDF (201KB) ( )   A new method is presented for calculating the quasi steady transonic flow over a lifting rotor blade in hover by using Euler equations. The approach is to solve the Euler equations in a rotor fixed frame of reference using a finite volume method. The results are verified by comparison with wind tunnel data. In cases considered, good agreement is found with available experimental data.

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NUMERICAL STUDIES OF IGNITION AND REACTIVE FLOW WITH AN ADAPTIVE MESH METHOD Zhu Guangsheng, Wu Chuijie 1997, 14(6): 846-850.  Abstract ( )   PDF (205KB) ( )   An efficient adaptive mesh method is prestmted for constituting automatically the numercal grids to adapt the severe change of space scales of ignition and reactive flow problems. By combining this technique with ALE numerical method, a set of partial differential equations that control droplet ignition and combustion process is solved. The results obtained turn out clearly the space time distributions of physical parameters of gas phase around the droplet and show the calculation efficiency is greatly improved while without a loss of accuracy.

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STUDY OF THE RECONSTRUCTION OF THE EAS EVENTS AT ULTRA HIGH ENERGIES Luo Guangxuan, Tan Youheng, Zhang Chunsheng, Zhang Huimin 1997, 14(6): 851-856.  Abstract ( )   PDF (225KB) ( )   Taking into account of various factors which effect the reconstruction precision of EAS events and selecting some suitable optimum algorithn (such as simplex method algorithm, DFS algorithm). A new software EAS-FIT is made, which is of wider use and described briefly with some applications. This new software was been used to analyse the EAS raw data of Beijing Huairou array. The results show that it can improve overall precision of the array and greatly increse the speed of off line reconstruction (20-120 times faster than the old one). In addition, some important physics results can be obtained such as energy spectrum at the ‘keen’ region and so on.