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25 September 1992, Volume 9 Issue 3 Previous Issue    Next Issue

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LMTO-ASA-VCA METHOD AND ELECTRONIC STRUCTURE OF (Ba1-xKx)BiO3 SYSTEM Shen Yaowen, Wang Renzhi, Huang Meichun 1992, 9(3): 223-231.  Abstract ( )   PDF (599KB) ( )   On the basis of LMTO-ASA band calculation method, the electronic structure of (Ba1-xKx)BiO3 system was obtained by using a virtual crystal approximation (VCA) in which the atomic sphere radii and potential parameters in different compositions are determined by linear interpolation. We contrast the composition dependence of the VCA electronic structure with those of the expended unit cell method. It is shown that the VCA method was valid for such a complex system. The accuracy of our LMTO-ASA-VCA results is also discussed.

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APPROXIMATE CALCULATIONS OF SCATTERING ANGLE FOR BINARY COLLISION Shao Qiyun 1992, 9(3): 232-240.  Abstract ( )   PDF (488KB) ( )   In this paper, some interatomic potentials in studies of the interaction of energetic particles with solid targets are presented, the methods and results of approximate calculations of scattering angle for binary collision in crystalline and amorphous solids are given. The obtained conclusions is significative for computing axial blocking dips, surface peak intensity as well as sputtering by using Monte Carlo simulation.

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AN ACCURATE CALCULATION FOR IMPACT IONIZATION CROSS SECTIONS OF ATOMS BY ELECTRON Chen Xuejun 1992, 9(3): 241-249.  Abstract ( )   PDF (449KB) ( )   A theoretical method called multiple-scattering expansion was proposed and developed by author in the previous works[1].This method has a few advantages, such as,high accuracy, simplicity for calculations and wide valid region. This method has been applied to calculations for the impact ionization cross sections of H-atoms, and the results are in agreement with the experimental data very well[2]. A detailed description for practical calculations based on this method is given in the present paper.

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PARALLEL ALGORITHMS FOR SOLVING THE IMPLICIT DIFFERENCE EQUATIONS Zhang Baolin, Su Xiumin 1992, 9(3): 250-256.  Abstract ( )   PDF (340KB) ( )   The parallel algorithms for solving the implicit difference equations have been studied in the paper. The basic idea is to divide the system of difference equations into a set of subsystems which can be solved in parallel. The direct method and iterative method are given and the convergence theorem on the iteration is proved. To show the efficiency of the segment implicit iteration, the papper gives the numerical experiment for an example of the diffusion equation.

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STUDY OF NON-MARKOVIAN THERMAL ACTIVATION PROCESS USING THE SAMPLING TRAJECTORIES METHOD Bao Jingdong 1992, 9(3): 257-262.  Abstract ( )   PDF (329KB) ( )   A sampling trajectories-Monte Carlo method for solving non-Markovian Langevin equation driven by harmonic colored noise and with memory-damped is presented based on increased of four-dimensional phase space. The activation rates for the case of impurity diffusion in the host crystalline solid are calculated. An initial distribution of colored noise overlooked in the past for getting stationary correlation of random force is derived. The stochastic resonance phenomenon by expressed theoretically is better shown.

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RESEARCH ON CHEMICAL KINETICS AND CALCULATION OF ENERGY DEPOSION IN KrF* EXCIMER SYSTEM PUMPED BY PROTON-BEAM Wang Xiaosha, Chen Dongquan, Wang Zhengyan 1992, 9(3): 263-266.  Abstract ( )   PDF (240KB) ( )   The computational program of chemical kinetics of KrF* excimer laser pumped by e-beam is modified. The kinetics and energy deposition for the mixture system of Ar, Kr and F2 pumped by proton-beam is calculated. The results show that deposited energy is about 50 times as much as by e-beam-pumping for the same pressure, the same mixture of the gases and the same current density.

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IN ONE-DIMENSIONAL DISORDERED Xu Hui 1992, 9(3): 267-273.  Abstract ( )   PDF (438KB) ( )   A new method for solving directly a hermitian five diagonal matrix is applied in this paper. The electronic eigenvectors are obtained in one-dimensional Anderson disordered model with second-neighbour interaction and 500 to 10000 site points. The result shows the change of eigenvectors in this model from the extended state to the localized state with the increasing of site point and the change speed is affected by the degree of the system disorder.

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STUDY OF MULTI-DIMENSIONAL NEUTRONICS CALCULATION OF THE FUSION-FISSION HYBRID EXPERIMENTAL REACTOR Liu Cheng an, Liu Chaofen, Huang Zhengfeng, Liu Zhongxing 1992, 9(3): 274-278.  Abstract ( )   PDF (303KB) ( )   In this parper, the neutronics performance of a solid breeder blanket of a elementary designed fusion-fission hybrid experimental reactor has been studied in one-, two-, three-dimensional analysis and comparison. For being easy to describe the complicated geometry of the Tokamak torus, the neutron and gamma ray coupled transport calculation has been performed with the help of the Monte Carlo code MCNP. For avoiding uncertainties and errors involved in the generation and application of group constants and self-shielding effects, a continuous energy representation of the nuclear data base has been used.The main concern of the study has been the assessment of the spacial distribution of the tritium breeding ratio, the plutonium breeding ratio, and the power density in multi-dimensional configuration and the comparison between One-, two-, three-dimensional global calculation. The role and the limitation of one dimensional calculation has been pointed out.

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APPLICATION OF THE BOLTZMANN TRANSPORT EQUATION TO ION RANGE IN TARGETS Zhang Qingyu, Gong Ye, Ma Tengcai 1992, 9(3): 279-284.  Abstract ( )   PDF (364KB) ( )   The Boltzmann transport equation and the new results obtained in the interaction between the particle and solid materials research are applied to calculate the ion range in targets. The results calculated are compared favorably with experimental results and the results calculated by the famous Monte carlo code TRIM.

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APPLICATION OF THE BOUNDARY ELEMENT METHOD IN INTEGRATED CIRCUIT CAD Wu Qiming, Wang Zeyi 1992, 9(3): 285-292.  Abstract ( )   PDF (465KB) ( )   A new algorithm based on the Boundary Element Method (BeM) is employed to calculate two-dimensional multi-terminal resistance of irregular polygons and two-dimensional capacitance with complex structures. The same calculation program can be used for computation of both resistance and capacitance, only the post-process programs are different. For BEM only the integral equation on the boundary of the solved domain needs to be calculated. The grid number on the boundary for BEM is much smaller than the mesh number on the domain for both the finite difference Method and the finite element method. It causes remarkable reduction of execution CPU time and simplification of the grid generation. The computational results indicate that the advantage of BEM is high precision and very powerful for treatment of complex boundaries.

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NATURAL CONVECTION HEAT AND MASS TRANSFER ON A VERTICAL PLATE FOR WATER IN SUPERCRITICAL PRESSURE STATES Jiang Peixue, Ren Zepei, Wang Buxuan, Protopopov V. S., Kuraeva I. V. 1992, 9(3): 293-302.  Abstract ( )   PDF (657KB) ( )   The deposit of the ferric corrosion products on surface of the tubes in boiler equipment or nuclear power station under the high pressure states will influence on operating economy of the equipment and even result in accident. The corrosion products of structure materials may be soluble or suspended in water after water treatment. The particles diameter is about 10-3-10-1μm. Here the conjugate problem of natural convection heat and mess transfer on a heated vertical plate subject to the boundary conditions of the first kind or mixed for water containing of the ferric corrosion products in superoritical pressure states with consideration of the states dependence of the thermal properties was reported. The mechanism of the natural convection heat and mass transfer was revealed and the influence of the states dependence of the thermal properties was analyzed quantitatively in supercritical pressure states. A correlation for natural convection heat and mass transfer in this case was recommended in this paper.

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THE FINITE DIFFERENCE METHOD OF THE BENDING PROBLEM OF SMALL DEFLECTION OF THIN ELASTIC PLATES OF NON-HOMOGENITY AND VARIABLE THICKNESS ON NON-HOMOGENEOUS ELASTIC FOUNDATIONS Qu Xiaogang, Pan Dingkun, Feng Shoudai 1992, 9(3): 303-312.  Abstract ( )   PDF (507KB) ( )   Starting from the principle of the minimum potential energy, the governing differential equation and the boundary constraint conditions for the bending problem are differenced unitedly and the difference schemes which depend only on the mesh points in plate area are obtained. A method to solve the difference equations by means of combining the direct manner with Gauss-Seidel iteration method is proposed. And a numerical example is given in the paper.

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INVERSE EIGENVALUE PROBLEMS FOR JACOBIAN MATRICES Lü Tongxing, Geng Changhong 1992, 9(3): 313-322.  Abstract ( )   PDF (507KB) ( )   This paper considers the following two inverse eigenvalue problems:Problem Ⅰ. Given λ,μ∈R, λ > μ, and x, y∈Rn:x≠0,y≠0, xTy=0. Find n×n Jacobian matrix J such that Jx=λx, Jy=μy; λ > μ > λ3(J) > … > λn(J)(or λ1(J) > … > λn-2(J) > λ > μ).problem Ⅱ. Given x∈Rn, x≠0, and n distinct real numbers λ1,λ2,…,λn which satisfy λ1 > λ2 > … > λn. Find n×n Jacobian matrix J such thatλi(J)=λi, i=1,…,n; Jx=λ1x (or Jx=λnx)Some necessary and sufficient conditions for existance of solution of these problems are given. For the problem Ⅰ, the expression of the solution is given. For the problem Ⅱ, a numerical algorithm is provided.

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ESTI MATES OF ‖A-1‖∞ AND EQUIDIAGONAL-DOMINANCE (2) Hu JiaGuan 1992, 9(3): 323-329.  Abstract ( )   PDF (368KB) ( )   In this paper, some estimates of ‖A-1‖∞ based on our previous paper are given, The relation between these estimates and Varga's estimate in [2] is illustrated. For several interesting matrices the norm ‖A-1‖∞ are found by use of our method, These examples show that our method is preferable.

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STUDY OF THE INFLUENCE OF AXIAL DISPERSION ON THE ELUTION PROFILE IN NONLINEAR CHROMATOGRAPHY USING THE GALERKIN METHOD Wang Kaiming, Lin Bingchang 1992, 9(3): 330-334.  Abstract ( )   PDF (264KB) ( )   In this paper, Using the Galerkin method, the study is made, which is about the Inflence of axial dispersion on the elution profile and retention time tR in nonlinear chromatography, The results show that when the diffusion coefficient D increases, the elution curve changes from "shock type" to "Gauss type", and the rate of chang of tR due to D from positive to negative.