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25 November 2006, Volume 23 Issue 6 Previous Issue    Next Issue

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A Sort of Birth-Death Process and Application in Nuclear Astrophysics WU Kai-su, ZHANG Yan, LIU Xiao-jing, XUE Ya-ping 2006, 23(6): 631-636.  Abstract ( )   PDF (223KB) ( )   A sort of birth-death process is investigated.We calculate eigenvalue,eigenvectors of the main matrix for the birth-death process differential equation and get a similar decomposition of the main matrix.Using the technique of matrix decomposition,we obtain the solution of the birth-death process differential equation and study the heavy element abundance of the slow neutron capture process(s-process) in the solar system.A full calculation of heavy element abundance of s-process in solar system is carried out.The result agrees well with astrophysical measurement.

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A Parallel Algorithm for the Particle Transport SN Method with Interface Corrections YUAN Guang-wei, HANG Xu-deng 2006, 23(6): 637-641.  Abstract ( )   PDF (313KB) ( )   In order to make conventional implicit algorithm to be applicable in large scale parallel computers,an interface correction method is introduced to solve the particle transport SN equations.Domain decomposition is adopted in the computational domain.On the interface,an upwind explicit scheme is applied to give an incident boundary condition,which enables the subdomain problem iterated independently.The interface values are updated by an implicit scheme concurrently in iteration.The scheme shows good precision,parallelism and simplicity in numerical experiments.

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A Model of Disc Pile with Silo Effect ZHANG Xing-gang, HU Lin, LONG Zheng-wen 2006, 23(6): 642-646.  Abstract ( )   PDF (265KB) ( )   A model of planar disc pile is applied to complicated granular matters.We analyze force transfer in the disc pile.Numerical simulation shows that the pressure on the cylinder bottom saturates with increasing height of granules.The rule of the planar disc pile is extended to three-dimensional granules and the relation between the height Z of granules and the average pressure p on cylinder bottom is obtained.

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Virtual Boundary Method and Electron Trace in a Power Electron Gun YIN Hai-rong, GONG Yu-bin, WEI Yan-yu, HUANG Min-zhi, LU Zhi-gang, WANG Wen-xiang 2006, 23(6): 647-654.  Abstract ( )   PDF (419KB) ( )   We derive a foundational equation in the virtual boundary method,and essential conditions that the virtual boundary must satisfy.It shows that the virtual boundary element method is rigorous.For complex real boundaries,such as a concave boundary,it is approximate because the requirements for virtual boundary can not be satisfied.Code for electron trace in a power electron gun is explored.It shows that the accuracy of the virtual boundary element method is better than that of the boundary element method as the distance between virtual boundary and real boundary is optimum.

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Analysis of 2-D Dielectric Photonic Crystals Using the Method of Lines LIN Bao-qin, YUAN Nai-chang 2006, 23(6): 655-660.  Abstract ( )   PDF (344KB) ( )   The bandgap structure of 2-D dielectric photonic crystals is analyzed using the method of lines(MoL).The eigenvalue equation for 2-D dielectric photonic crystals is derivated.The photonic crystals with different parameters are computed and the results are validated by FDTD and published results.The TE and TM band gaps are considered, which gives a reference to the design of dielectric photonic crystals.

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Nonlinear Attenuation of Electromagnetic Wave in Plasma WANG Xiao-yan, LI Guo-feng, ZHAO Hong-kang 2006, 23(6): 661-664.  Abstract ( )   PDF (187KB) ( )   Nonlinear absorption and attenuation of electromagnetic plane wave in plasma are investigated.We employ a polarization theory of plane electromagnetic wave in plasma to obtain a nonlinear dynamic dielectric function.The wave vector is obtained considering linear and nonlinear effects.In a model with vertical incidence of plane electromagnetic wave into plasma slabs with metal underlay,the attenuation of electromagnetic wave and reflected power are deduced.It shows that the nonlinear effects should be considered.

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Simulation of Coupled Electric-Magnetic-Flow Fields in an Aluminum Reduction Cell JIANG Chang-wei, MEI Chi, ZHOU Nai-jun, LIU He-yun, FU Jun-ping 2006, 23(6): 665-672.  Abstract ( )   PDF (511KB) ( )   Based on the basic theory of magnetohydrodynamics,the current field in an aluminum reduction cell is calculated using an equivalent resistance method(ERM) and a finite element method(FEM).The magnetic field in alumium reduction cells is calculated using a scalar voltage potential method and a two scalar magnetic potential method.The flow field in aluminum reduction cells is calculated using a two equation k-ε model.A comparison of measured and calculated results in a 200 kA aluminum reduction cell shows good agreement.It is found that the horizontal magnetic field forms a clockwise whirlpool and the vertical magnetic field presents an antisymmetry distribution.The flow field in aluminum reduction cells presents four whirlpools along the X axis.The errors of the magnetic field and the flow field are less than 10.0% and 5.0%,respectively.

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Enhanced Heat Transfer of Pulsating Flows in a Wavy Channel XIE Gong-nan, WANG Qiu-wang, ZENG Min, LUO Lai-qin 2006, 23(6): 673-678.  Abstract ( )   PDF (370KB) ( )   A fully developed convective heat transfer inside a two-dimensional periodically wavy channel is investigated numerically with pulsating flows under a constant wall temperature. It is based on the SIMPLER(Semi-Implicit Method for Pressure Linked Equations Revised) algorithm in curvilinear body-fitted coordinates.Calculations are performed with Pr=0.7,Re=5~500 on a non-orthogonal non-staggered grid generated by elliptic equations. The effects of pulsatile parameters,such as pulsatile amplitude and frequency on heat transfer and flow friction,are studied.It shows that the vortice sweeping,diminishing and growing up due to pulsating flows enhance fluid pulsating and mixing,and lead to the enhancement of heat transfer.The intensity of heat transfer increases with the increase of Reynolds numbers and amplitudes and is independent of pulsating frequencies.The instantaneous flow resistance and Nusselts numbers present periodical cosine and sine variations, respectively.

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Numerical Investigation of Premixed Combustion Within a Two-layer Porous Burner ZHAO Ping-hui, ZHU Min-ming, ZHANG Gen-xuan, CHEN Yi-liang, JIANG Hai 2006, 23(6): 679-684.  Abstract ( )   PDF (342KB) ( )   CH4/Air premixed combustion within a two-layer porous medium burner is numerically simulated in a laminar combustion model.Heat exchanges with radiation in the solid and with convection between the gas and the solid are considered.A detailed reaction mechanism GRI 3.0 is used and a dispersion formula is added to the equations.The stabilization of the flame and the emission output are investigated.The results are compared with those of a one-layer burner.It is concluded that a two-layer burner has wider flux range in stabilizing the flame nearby the two-layer porous medium interface.

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Two-dimensional Theoretical and Numerical Investigation of Gaseous Slip Flows in a Micro-channel ZHANG Gen-xuan, LIU Ming-hou, CHEN Yi-liang, WANG Lu 2006, 23(6): 685-691.  Abstract ( )   PDF (402KB) ( )   In a perturbation analysis,a two-dimensional theoretical solution based on Navier-Stokes equations is constructed for gaseous slip flows in a micro-channel with different slip conditions.The micro-channel flow is investigated theoretically and numerically at various inlet pressure ratios,aspect ratios and fluid cases with several slip models.The influence of the rarefaction effect,thermal creep effect and slip conditions is emphasized.Simulations show that Kn is a key parameter in determining the magnitude of rarefaction effects while Re is a key parameter indicating the thermal creep.Excellent agreements with experimental results are observed in both theoretical and numerical results of low-velocity micro-channel flows at very large aspect ratios.

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Energy Transfer in Scalar Turbulence FANG Le, CUI Gui-xiang, XU Chun-xiao, ZHANG Zhao-shun 2006, 23(6): 692-698.  Abstract ( )   PDF (548KB) ( )   With DNS database,we study the triad interaction of scalar energy transfer,and make a multi-scale analysis in different scales.It shows that the energy transfer in scalar turbulence is different from that in velocity fluctuations.The major contribution of scalar transfer is given by large scale turbulence.Simulation of scalar turbulence requires a higher resolution.The interation between large scale velocity fluctuations and small scale scalar turbulence is an important part of the energy transfer.Non_energy transfer is as important as the local energy transfer in the scalar turbulence.We define an energy transfer coefficient,and find that the inertia_convective range in scalar turbulence is longer than the inertial subrange in turbulent kinetic transfer with same Re and Pe numbers.

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An RKDG Finite Element Method for Two-dimensional Compressible Multimedia Fluids CHEN Rong-san, YU Xi-jun 2006, 23(6): 699-705.  Abstract ( )   PDF (313KB) ( )   The RKDG(Runge-Kutta Discontinuous Galerkin) finite element method,the Level Set method and the Ghost Fluid method are applied to compressible multimedia fluids.We discretizes Euler equations,the Level Set equation and the reinitialization equation by a DG(Discontinuous Galerkin) method in space and by a Runge-Kutta method in time.Two dimensional compressible two-fluid flows such as air-air,air-liquid are computed.High resolution ratio computational results are obtained.

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A Quadrature Method and Splitting Extrapolation for Second-kind Boundary Integral Equations in Elasticity Problems HUANG Jin, ZHU Rui, Lü Tao 2006, 23(6): 706-712.  Abstract ( )   PDF (309KB) ( )   With singular quadrature rules,a quadrature method for the second-kind boundary integral equations in linear elasticity problems on polygonal domains is proposed.The discrete matrix can be obtained with no Cauchy singular integral.With the collectively compact convergent theory,we establish a convergence theorem of approximation and get multivariate asymptotic expansions of error.Solving the discrete equations with coarse meshed partitions in paralle,high accurary approximations are obtained by the splitting extrapolation.A posterior error is derived.

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A Modified SPH Method Based on Riemann Solution XU Zhi-hong, TANG Wen-hui, ZHANG Ruo-qi 2006, 23(6): 713-716.  Abstract ( )   PDF (201KB) ( )   An interparticle contact algorithm based on Riemann solvers and an interpolation method in which the Taylor series incorporates with a kernel estimation are combined to construct a modified smoothed particle hydrodynamic algorithm.Numerical simulations show that the modified algorithm ensures numerical solution accuracy on the boundary and eliminates tensile instability occurred at contact interfaces in impact problemes.It removes numerical compression instability which appears in corrective smoothed particle method (CSPM) as the domain of influence of a kernel function includes many particles or the gradient of the flow is sharp.

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Numerical Boundary Condition of Euler Equations in Cylindrical Coordinate Tian Bao-lin 2006, 23(6): 717-720.  Abstract ( )   PDF (268KB) ( )   A method for the treatment of polar singularities of Euler equations is given. The first radial mesh point locates at a half-space away from the centerline. Based on the characteristics of the physical variables,the boundary near centerline is extended so that a high order finite difference scheme can be utilized as at inner mesh points.Similarly,in azimuthal direction the boundary is extended according to the periodicity.An uniform high-order precision is preserved during discretization of equations.

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A Finite Difference Scheme for Two-dimensional Semiconductor Devices on Composite Grids LIU Wei, YUAN Yi-rang 2006, 23(6): 721-730.  Abstract ( )   PDF (484KB) ( )   The momentary state of a semiconductor device is described with three nonlinear partial differential equations. A finite difference scheme for transient behaviors of two-dimensional semiconductor devices on grids with local refinement in time and space is constructed and studied.The electrostatic potential equation is approximated by a five-point difference scheme.The electron and the hole density equations are discretized by a modified upwind scheme.The construction uses a linear interpolation at slave nodes.An error analysis is presented and illustrated with a numerical example.

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Numerical Study on the Bottom Friction Coefficient of the Bohai,Yellow and East China Seas ZHANG Ji-cai, ZHU Jian-guo, Lü Xian-qing 2006, 23(6): 731-737.  Abstract ( )   PDF (553KB) ( )   Based on the simulation of the M2 tide in the Bohai,Yellow and East China Seas,numerical experiments are made to study 4 strategies on the bottom friction coefficient(BFC) in a numerical adjoint model.In order to make a better simulation,the strategy must be consistent with the given BFC distribution.The real bottom friction decided by ocean topography is very complicated and an independent BFC is required.The fourth method which takes the BFC in each grid point as an independent BFC simulates practical experiments best and demonstrates the reasonability and efficiency of this method.

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Numerical Simulation of a Flat Planetary Fixture for Physical Vapor Deposition FANG Ming, FAN Zheng-xiu, HUANG Jian-bing 2006, 23(6): 738-742.  Abstract ( )   PDF (336KB) ( )   A thin film deposition dimensionless model for flat planetary fixture is developed.Optimal geometric configurations with theoretical representative radial uniformity are acquired by analyzing the evaporating source location L/H,the distance between the main axis and the secondary axis P/H,the slope angle of fixture A and the emissive characteristics of vapor source N.An optimum design zone is shown by evaluating optimal geometric configurations with coating materials efficiency,angular uniformity and emissive characteristics sensitivity.The results indicate that the thickness via angular distribution is more uniform as L/H+P/H is small and the coating material efficiency is higher when both L/H+P/H and A are small;As L<P and A=-15deg,the optimal geometric configurations are more insensitive to N;As L>P,the change of the representative radial distribution due to the change of the emissive characteristics is less than 0.5%.

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A Monte Carlo Simulation of Penetration Depth and Concentration Distribution for 200keV Vanadium Ions Implanted into Peanuts WANG Lin-xiang, ZHU Heng-jiang, ZHANG Shi-feng, WANG Shi-heng 2006, 23(6): 743-747.  Abstract ( )   PDF (258KB) ( )   In one- and two- dimensional approximations,the penetration depth-concentration distribution for 200 keV vanadium ions implanted into peanuts is simulated using a Monte Carlo method.The calculation is in good agreement with experimental results.The depth-concentration distribution for nitrogen ions with low energy implanted into peanuts is calculated which can not be obtained with experiment.It provides a computational method for the depth-concentration distribution of ions with low energy implanted into seeds.

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LU-SGS Scheme and Improvement for Euler Computation on Three-Dimensional Unstructured Grids LI Jin-jie, YANG Qing, YANG Yong-nian 2006, 23(6): 748-752.  Abstract ( )   PDF (266KB) ( )   An LU-SGS(Lower-Upper Symmetric Gauss-Seidel) scheme and improvement for three-dimensional unstructured grid Euler computation are presented.Grid reordering for efficient implementation of the improved LU-SGS and the original LU-SGS is proposed.In order to test the feasibility and efficiency of the improved LU-SGS algorithm,two numerical examples of transonic inviscid flow around an ONERA M6 wing and an LANN supercritical wing are presented.It shows that the numerical results agree well with the experimental data.Moreover,the efficiency of the improved LU-SGS scheme is two times higher than that of the original LU-SGS scheme and seven times higher than that of the explicit Four-Stage-Runge-Kutta scheme.

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MCM Interconnect Power Consumption in an S-domain RLC Transmission Line Model DONG Gang, YANG Yin-tang, LI Yue-jin 2006, 23(6): 753-756.  Abstract ( )   PDF (208KB) ( )   A power consumption equation of MCM (Multi-Chip Module) interconnect is presented in an S-domain RLC transmission line model. Simulation results are shown to verify the theoretical analysis.