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25 July 1999, Volume 16 Issue 4 Previous Issue    Next Issue

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Numerical methods of calculating periodic solutions Zhang Suochun 1999, 16(4): 337-345.  Abstract ( )   PDF (321KB) ( )   A synthetic description on numerical methods is given for calculating periodic solutions of autonomous ordinary differentical equaitons.It focuses on the introductions of original structural ideas and processes of the methods or algorithms.

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Calculations of overtones and com binations of ch 4 molecule using nonlinear quantum theory Chen Xiangrong, Cheng Yan, Gou Qingquan, Pang Xiaofeng 1999, 16(4): 346-350.  Abstract ( )   PDF (205KB) ( )   A simple three-parameter dynamical model in nonlinear quantum theory-the quant ized discrete self trapping equation is used to calculate the highly excited vi brational spectrum of CH stretches of CH4 molecule with up to total quantum number n=7. The results show the model calculations appear to describe the expe rimental data well.

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Study on ion dipole mixtures by use of cluster expansion method Lu Guiwu, Zhou Kaixue, Chu Jun, Ren Lanting 1999, 16(4): 351-357.  Abstract ( )   PDF (252KB) ( )   Based on the interaction of all particles in solution,a mixture of ions and point dipoles as an electrolyte solution is proposed.The partition functions,Virial coefficient and internal energy are calculated by using cluster expansion method. It is found that the partition function can be expanded in cluster integrals whi ch are easily calculated without three body interaction.Related numerical resul ts have been given and discussed.

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Computing classical trajectories of H2 and O2 in murrell-sorbie diatomic potential Li Guiqin, Zhou Qian, Liu Shuqin 1999, 16(4): 358-361.  Abstract ( )   PDF (166KB) ( )   Classical trajectories of diatomic system H2 and O2 are calculated by means of symplectic algorithms in Murrell Sorbie diatomic potential. The results have been compared with the experiment and theory, and show that the classical trajectories are quite glossy.

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Simulation and numerical reconstruction of photoelectron holography Gu Changxin, Han Jihong, Lu Wei, Liu Jian, Hua Zhongyi 1999, 16(4): 362-371.  Abstract ( )   PDF (472KB) ( )   Photoelectron outgoing wave emitted from core state of excited atom will be scattered by near neighbor atoms.Scattered waves (object waves) which contain structural information of the environment around the excited atom interfere with the original one(reference wave)which propagates directly to the detector,and then a diffraction pattern,i.e.a photoelectron hologram,will be created.A complete 3 D image of the structure surrounding the emitter with at omic resolution can be reconstructed.This paper gives computer simulation for ca lculat ing photoelectron holograms of small atomic clusters on c(2×2) S/Ni(100) surface,in metal copper,and on puckered Cu2O plane of superconductor YBCO.

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Cohesive energy of elemental crystals:extended application of the linearized augmented planewave band method Geng Wentong, Zhou Yumei, Wang Dingsheng 1999, 16(4): 372-394.  Abstract ( )   PDF (788KB) ( )   All-electron self-consistent linearized augmented planewave band method in the local spin density functional and warped muffin tin approximation is used to calculate the cohesive energy of as many as 58 elemental crystals including not only simple, noble and transition metals, but also the covalent and inert gas so lids. Calculation scheme for achieving good results for this wide range of cryst a ls is thoroughly discussed. The numerical results are in general agreement with those of other band-structure methods and the experimental data.

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Simulation of the rlw equation using a lattice boltzmann model Yan Guangwu 1999, 16(4): 395-400.  Abstract ( )   PDF (224KB) ( )   A 5-Bit lattice lattice Boltzmann model is pr oposed for RLW equation.Using Chapman Enskog expansion and multiscale technique,it obt a ins the higher order moments of equilibrium distribution function,the 3rd dispers ion coefficients and 4th order viscosity.The parameters in this scheme can be de termined by analysis of the stability.

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The study and modification of upwind tvd scheme for computing viscous flows Zhou Weijiang, Jiang Guiqing 1999, 16(4): 401-408.  Abstract ( )   PDF (405KB) ( )   Firstly, from the calculations of the heating rate on a blunt body in hypersonic flow and separation of shock/boundary layer interac tion flow, the capability of upwind TVD scheme for computing viscous flows is st udied. It is found that the computed heating rate and separated region are lower than the experimental data. The problem is the entropy correction formula. Then a new entropy correction formula is proposed, and the agreeable results compared with experiment are obtained. Secondly, using modified scheme, the study of control of separated flow over a smooth surface by body wall temperature is completed. The results show that the change of wall temperature can control the locati on of separation point and separation region effectively.

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The application of generalized fluid concept in flow and heat transfer analysis model of continuous casting Jin Zhumei, He Jicheng, Di Hongshuang 1999, 16(4): 409-413.  Abstract ( )   PDF (200KB) ( )   Twin-roll continuous strip casting process has been simulated by using generalized fluid concept based on considerations of fluid fl ow, heat transfer and solidification. The simulation result shows that there is a relatively large range of circumfluent area in the pool, which acts as the mec hanical agitator. This conclusion provides a theoretical foundation for twin ro ll casting to produce high quality strip. The method proposed can be used in var ious fields where the conjugate of solidification heat transfer and fluid flowis dominant, such as metallurgy and petroleum engineering.

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High resolution euler methods for multi component flow Dong Haitao, Fu Hongyuan 1999, 16(4): 414-421.  Abstract ( )   PDF (326KB) ( )   In multicomponent flow, different component has diffe rent equation of states. This makes the flux discontinuous and no Jacobian matrix exists. In schemes of high resolution for Euler equations, the Jacobian matrix and its eigenvalues as while as its eigenvectors are needed, that is, the flux should be continuously differentiable. So the whole systems of conservation laws should be rearranged. For γ gas, γ is regarded as a new unknown and a new con servation equation is added, thus the flux of the new system become continuously differentiable, the obstacles in the way to high resolution schemes are removed . Since true flows only obey three conservation laws, though the additional cons ervation law does not influence the exact solutions of original differential equ ations, it does influence the numerical solutions of difference equations. This is obvious in numerical experiments. The presented method eliminates this influe nce as much as possible. All schemes of single component flow can be directly us ed. Numerical experiments for one dimensional shock tube problem of multicompone nt flow demonstrate that so designed schemes have the same effect as those of on e component flow.

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Parallel computation for molecular dynamics problem on the now (network of workstation) Zhu Yuxiang, Zhang Jinglin 1999, 16(4): 422-427.  Abstract ( )   PDF (224KB) ( )   The shock compression of condensed matter can be effe ctively dealt with by molecular dynamics,and has been applied to many fields of science.However,there is large scale computation in molecular dynamics,so it is very important to develop the parallel and optimizing algorithm.An approach to the parallelization and optimization is proposed on the NOW (Network of Workstation),and has got the satisfactory result.

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Circuit model for phase_shifted distributed feedback semiconductor lasers Chen Weiyou, Liu Shiyong 1999, 16(4): 428-435.  Abstract ( )   PDF (285KB) ( )   A simple circuit model is presented for phase-shifted and single-longitudinal-mode distributed feedback semiconductor lasers. Th is model can be used for DC, AC and transient simulation. The simulated results with this model agree with the reports.

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Uniform shear flow of fluidized gas solid granular flow at low concentration Lu Huilin, Zhao Guangbo, Liu Wentie, Bie Rushan 1999, 16(4): 436-441.  Abstract ( )   PDF (223KB) ( )   The steady uniform shear flow in a low concentration fluidized gas solid granular flow is studied on the basis of the kinetic theory of granular flow and a modified BGK model equation. Explicit expressions of the pressure tensor are obtained as a function of the restitution coefficient. The computation shows the different normal stresses distribution. The results agree well with the Jenkins Richman theories, although significant discrepancy appears for granular temperature distributions.

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Pulse characteristics study for uzrh pulsed reactor Jing Chunyuan, Chen Da, Zhu Jizhou 1999, 16(4): 442-448.  Abstract ( )   PDF (318KB) ( )   It gives the pulsing parameter formulae based on Fuchs-Hansen's adiabatic model, calculates the kinetic parameters of Xi'an Pulsed Reactor when various reactivities are inserted, and analyses the influences of wat er channel and Mo-Tc target on the core safety parameters.