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25 December 1994, Volume 11 Issue 4 Previous Issue    Next Issue

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NUMERICAL SIMULATION OF THE FLOW FIELD HEAT AND MASS TRANSFER IN A NATURAL DRAFT COOLING TOWER OF COUNTERFLOW Mao Xianzhong, Chen Yunwen, Huang Dongtao 1994, 11(4): 385-392.  Abstract ( )   PDF (466KB) ( )   With a hyperbolic natural draft cooling tower of counterflow to be a typical pattern,mathematical and physical models are proposed for fluid flow,heat and mass transfer between air and water inside the tower,in which a "thermal state model" is adopted. The governing equations are discretized in a body-fitted curvilinear near-no nonorthogonal coordinate system and finite-volume method is employed. The SIMPLE algorithm is applied to calculate the flow and temperature field inside the cooling tower. Numerical results are satisfied.

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APPLICATION OF EBE STRATEGY IN STRUCTURAL ANALYSIS (Ⅲ)-BE-PCG METHOD Deng Shaozhong, Zhou Shuquan 1994, 11(4): 393-401.  Abstract ( )   PDF (476KB) ( )   Important concepts such as element vector, pseudo-element valor are discussed and an EBE cpmputational method of preconditioned conjugate gradient method (PCG) is presented, namely EBE-PCG method, which does not require the formation of global stiffness matrix and is highly parallizable. Numerical example shows it is very efficient.

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APPLICATION OF EBE STRATEGY IN STRUCTURAL ANALYSIS (Ⅳ)-PARALLEL IMPLEMENTATION OF EBE-PCG METHOD Deng Shaozhong, Zhou Shuquan 1994, 11(4): 402-408.  Abstract ( )   PDF (465KB) ( )   By using multiprocessor systems equiped with local memory and shared memory as the hardware enviroment of the application, the implementation of EBE-PCG method is discussed. with especal attention on the problems relating to configuration of tasks,storation and visiting of datas,communication and synchronization. Finally,a structural analysis problem is solved by use of EBE-PCG method.The results show that the algorithm is effective numerical method for the super-large scale structural analysis problems.

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AN APPROACH TO EXPANDING NONCONSERVATION VECTOR EQUATIONS OF VISCOUS FLUID WITH NUMERICAL CALCULATIONS Zhang Chiping, Zhang Pingping, Feng Guotai 1994, 11(4): 409-412.  Abstract ( )   PDF (221KB) ( )   This paper gives an approach to expanding the nonconservation viscous vector equations in non-orthogonal curvilinear coordinates. In the expansion expression the number of terms included is greatly decreased, so the method can be easily used in engineering calculation. Numerical results of 2-dimension calculations in plane blade grid and in pressure-amplied pipe indicate the new approach of expansion very useful in practice.

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A COMPACT h4 SCHEME OF CENTRAL TYPE FOR ADVECTION-DIFFUSION EQUATION Chen Guoqian, Chen Maozhang 1994, 11(4): 413-424.  Abstract ( )   PDF (651KB) ( )   A compact h4 scheme of central type for the advection-diffusion equation is developed, based on the central difference scheme and via the perturbation technique, and applied to flow model equations with promising results.

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SUBSTRATE MODEL AND INTERACTING POTENTIAL OF METHYL WITH DIAMOND (Ⅲ) SURFACE Liu Bo, Li Yanxin, Qian Xingzhong, Pan Shoufu 1994, 11(4): 425-428.  Abstract ( )   PDF (284KB) ( )   The potential energy curves between methyl and diamond (Ⅲ) surface are calculated by Ami semi-empirical molecular orbital method, which are found to be in close agreement with the substrate models. It provides much information for studying the dynamic processes of the nucleation and growth of diamond films, and more general adsorption as well.

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THE STUDY OF TWO-PARTICLE IMAGING LIGHT INTENSITY Ye Zifen, Wang Guangming 1994, 11(4): 429-433.  Abstract ( )   PDF (284KB) ( )   Disc-particle model is used to calculate the imaging light intensity of two on-axis particles, and results show that the region near N=0.1 has effective interaction of two particles.Because of scattered light of particles, the image and diffracted figure of particles have been distorted which relates to averaged number of far-field particles; small particle signals can be missed with easy.

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“CONSERVATION-MAP”ALGORITHM OF CHARGE DEPOSITION Wang Shijun, Liu Jun, Xicao Xuezheng, Shi Jiangiun, Zhang Guanren 1994, 11(4): 434-438.  Abstract ( )   PDF (300KB) ( )   From the map function of orbit radius, an algorithm is presented for determinating the bounds of the integration in the "Conservation-Map" formulae of charge deposition and the precision of charge deposition, and hence makes the "Conservation-Map" method of charge deposition feasible.

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DYNAMICAL PHASE TRANSITION IN THE MIXED SPIN MODEL Liu Cejun, Hu Jiazhen 1994, 11(4): 439-443.  Abstract ( )   PDF (330KB) ( )   We studied the time evolution of two configurations of the mixed spin model according too metropolis dynamics, and analysed the damage spreading on a square lattice.We found a high temperature phase and a low temperature phase,consistent with equilibrium results.

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THE COMPUTATION OF BESSEL FUNCTIONS OF IMAGINARY ORDERS Fan Guoxin, Yang Qjii 1994, 11(4): 444-450.  Abstract ( )   PDF (443KB) ( )   An integrated algorithm is presented for the computation of Bessel functions of imaginary orders and their derivatives. The numerical results show that the accuracy of the algorithm is more than 10 significant digits. In addition, the backward recurrence algorithm given can be extended to the one of complex orders.

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INVERSE EIGENVALUE PROBLEM FOR JACOBI MATRICES Dai Hua 1994, 11(4): 451-456.  Abstract ( )   PDF (320KB) ( )   The following inverse eigenvalue problem for Jacobi matrices is considered: Problem IEP.Given λ,μ∈R(λ<μ and x,y∈Rn,x≠0,y≠0, find n×n Jacobi matrix J such that (λ,x) and (μ,y) are exactly the i-th and j-th (i≠j) eigenpairs of the Jacobi matrix J, respectively. The eigenanalysis of Jacobi matrices is given. The necessary and sufficient condition is obtained for one eigenpair to be exactly the i-th eigenpair of a Jacobi matrix. Some necessary and sufficient conditions for existence of solution of the Problem IEP are given.

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ON THE SIMULATION OF THE ELECTROSTATIC FIELD OF PENNING TRAP BY STRUCTURAL ANALYSIS PROGRAM on Shengnian, Cui Zhenwei, Jiao Ke 1994, 11(4): 457-461.  Abstract ( )   PDF (303KB) ( )   Penning trap is an advanced equipment of microplasmas. To find its electrostatic field,a general "degenerated analogy method" is presented. As an application of this method, the electrostatic field is simply solved by structural analysis programs. The numerical result is consistent with the experimental result. The structural analysis programs are widely implemented by engineers and researchers. The users can simply extend their function to solve the engineering field problems not belonging to structural mechanics.

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ON THE DOUBLE DIMENSION PROBLEM FOR JACOBI MATRICES Lu Tongxing, Wang Xiaohong 1994, 11(4): 462-466.  Abstract ( )   PDF (270KB) ( )   The following inverse problem is discussed: Problem DD. Given a n×n Jacobi matrix Jn and a set of distinct real numbers λ1,λ2,…,λn, Construct a 2n×2n Jacobi matrix J2n whose eigenvalues are {λi}i-12n and whose leading n×n principal submatrix is Jn. The necessary and sufficient condition for the problem DD to have a solution is derived, and the algebraic expression of the solution is given if the solution exists. An algorithm of solving the problem DD is established on the basis of these results.

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2-D COMPRESSIBLE FLOW COMPUTATIONS IN COMPLEX DOMAINS WITH EULER EQUATIONS ON UNSTRUCTURED GRID Huang Mingke 1994, 11(4): 467-471.  Abstract ( )   PDF (345KB) ( )   A procedure of generating 2-D unstructured grids with Delaunay triangulation is proposed. The grid generated can be used to computation of compressible flow in complex multiply-connected domains. A computer code for flow computations with the use of Euler equations on unstructured grid by finite volume method of cell-centred formulation is then developed. Some of the computation results are given.

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NUMERICAL COMPUTATION OF MATHIEU FUNCTION AND ITS ADDITION THEOREM Ge Junxiang, Lin Weigan 1994, 11(4): 472-476.  Abstract ( )   PDF (297KB) ( )   Using the series expansion and the iterative multinomial expansion of the characteristic values of the Mathieu functions,Mathieu functions and its addition theorem are evaluated numerically.Calculated results are in largely conformity with the reference [1],and the precision appears an accuracy of better than 10-5 in the range r≤30 and 0≤ q≤ 50.

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INFLUENCE OF FIBER LOSS ON OPTICAL SOLITON PROPAGATION Zhong Weiping, Huang Nianning, Cheng Guoding 1994, 11(4): 477-480.  Abstract ( )   PDF (250KB) ( )   Propagation characters of optical soliton in single-mode fiber is studied by using Bäcklund transformation. The results show that optical soliton pulse width broaden as excp(2Γξ) and the faster soliton speed is, the smaller soliton intensity decays because of fiber loss.

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PARALLEL COMPUTATION FOR THE TWO-DIMENSIONAL FLUID DYNAMICS Yuan Guoxion, Zhang Baolin 1994, 11(4): 481-488.  Abstract ( )   PDF (529KB) ( )   This paper describes the experiences on vectorization and parallelization of te code YGX for te two-dimensional fluid dynamics at super computer YH-1 and YH-2, and gives some results of numerical experiments concerning the speed up on the computers.

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PENALTY UPWIND FINITE ELEMENT MODELING OF THERMOHALINE DOUBLE-DIFFUSIVE SYSTEM Zhang Diming, Li Lin, Chen Hong 1994, 11(4): 489-497.  Abstract ( )   PDF (514KB) ( )   A penalty upwind finite element method is adopted to deal with the thermohaline double-diffusive system.The method has good stability and second-order accuracy. Natural convection with lateral heating in a square rectangular enclosure can be examined by this way, and it's solutions approximate to the results obtained with velocity-pressure Method. Afterwards, the method is employed for a two-dimensional, laminar, with lateral heating, steady double-diffusive convection partitioned by an adiabatic baffle. Main computation is for Ra=106 and thermal buoyancy ratio N= 1,3,5,7. Distinct flow results depend on the magnitude of the thermal buoyancy ratio N and the baffle.

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THE PULSE COMPRESSION CRITERION IN DECONVOLUTION Wang Chengshu, Li Fenglin 1994, 11(4): 498-514.  Abstract ( )   PDF (914KB) ( )   Deconvolution methods based on the pulse compression principle are analyzed,and a more generalized lp-norm criterion for wide use is proposed,which in cludes as special cases pulse deconvolution,minimum-entropy deconvolution lt-norm deconvolution and D-norm deconvolution.According to the p-norm properties of the finite-dimensional space and the geometric properties of the higher-dimensional space,an analysis is made on the effect of the parameters in the generalized lp-norm method,and a criterion function is designed to compare pulse compression of different methods.It is also theoretically proved why for nonminimum-phase signals the l1-norm approach yields better pulse compression than pulse deconvolution,and why the D-norm approach has more "simplicity" than general minimum-entropy methods.New deconvolution methods can be readily constructed,and analyzed,by use of this generalized lp-norm criterion.The results provide a better understanding of the role these deconvolution methods play in enhancing the resolution and the theoretical basis for further study of the optimal pulse compression criterion and the algorithms to find its optimal solution in deconvolution.

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THE FINITE DIMENSIONAL NUMERICAL FORMULAR FOR INTERFACE ESTIMATION PROBLEM Pan kiaosu 1994, 11(4): 515-521.  Abstract ( )   PDF (357KB) ( )   Numerical discretization expressions for the interface estimation Problem used in [1] are described in detail.

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Mo-ALGORITHM IN ELECTRIC NETWORK DESIGN Wang Daqi, Li Qiaoxiang 1994, 11(4): 522-525.  Abstract ( )   PDF (264KB) ( )   Mo-algorithm is applied for electric network design, and faster convergent rate and higher precision results are obtained.

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THE METHOD OF TARGET-SHOOTING FOR SOLUTIONS OF THE TEMPERATURE-DENSITY DEPENDENT THOMAS-FERMI EQUATION Han Guoxing, Li Shichang 1994, 11(4): 526-528.  Abstract ( )   PDF (201KB) ( )   e propose a method of target-shooting which can be applied to solve th temperature-density dependent Thomas-Fermi equation. The convergence of this method is also discussed. The procedure of adjusting test parameters for calculations is given in detail. As examples, results of the calculations for Fe and Rb elements are presented.