UPWIND FINITE VOLUME SCHEMES FOR SEMICONDUCTOR DEVICE

The mathematical model of semiconductor devices is described by the initial boundary value problem of a system of three nonlinear partial differential equations. One equation in elliptic form is for the electrostatic potential; two equations of convection-dominated diffusion type are for the electron and hole concentrations. Finite volume element procedure are put forward for the electrostatic potential, while upwind     

Synthesis and crystal structure of the octahedral cluster complex [Th(DMSO)8Cl][Re6Se7Cl7]

A cluster complex of the composition [Th(DMSO)₈Cl][Re₆Se₇Cl₇] has been obtained by interaction of ThCl₄ solution in DMSO with a water solution of K₃[Re₆Se₇Cl₇] and KCl. The compound crystallizes in the rhombic space group Pbcm with unit cell parameters a = 12.262(2) Å, b = 19.653(6) Å, c = 23.603(6) Å, V = 5688(2) ų, Z = 4, d _calc = 3.282 g/cm³. The structure is built from centrosymmetric cluster anions [Re₆Se₇Cl₇]^3? and complex cations [Th(DMSO)₈Cl]³⁺ possessing mirror-plane symmetry, half of the DMSO ligands being doubly disordered.     

基于线性元的电阻抗成像的数学模型和算法

本文讨论了电阻抗成像的数学模型，先利用有限元方法将其离散化，再把它转化为非线性优化问题，并给出了利用牛顿法求解这一问题的具体算法．最后进行了一系列数值仿真对比实验，证实了这一算法的有效性，指出了其中存在的问题．     

地基基础-坝体体系动力特性及地震反应分析的有限元与无限元耦合法

编制了有限元及有限元—无限元耦合计算程序，利用其分析了广西源口拱坝在有限域及无限域地基下的动力特性与动力响应，并与常规刚性地基下坝体的动力特性、动力响应进行比较，得出结论：1．弹性地基下拱坝自振频率减小、动位移最大值增大；2．耦合分析法具有较高的精度和显著的经济性，是工程应用中值得推广的一种分析方法。     

Structural optimization design for large mirror

The system design must be started from the concept with low cost and high performance. In this point, the topological shape of the structure is very important in the view of the structural rigidities and light-weight design.In this paper, the optimization methodology is presented in the design stage of the large optical mirror. We obtain the optimal layout through the topology optimization and then design the details through the size or shape optimization for structural rigidity.     

Finite element computations of two-dimensional arterial flow in the presence of a transverse magnetic field

A finite element solution of the Navier-Stokes equations for steady flow under the magnetic effect through a double-branched two-dimensional section of a three-dimensional model of the canine aorta is discussed. The numerical scheme involves transforming the physical co-ordinates to a curvilinear boundary-fitted co-ordinate system. The shear stress at the wall is calculated for a Reynolds number of 1000 with the branch-to-main aortic flow rate ratio as a parameter. The results are compared with earlier works involving experimental data and found to be in reasonable qualitative agreement. The steady flow, shear stress and branch flow under the effect of a magnetic field have been discussed in detail.     

开关型磁阻电动机的振动分析

针对SR电动机存在的振动和噪声问题,分别应用实验模态分析法和计算模态分析法研究了SR电动机的动力特性,得到了SR电动机定子的固有频率和主振型,计算值与实验测量值吻合较好,所得数据可为制定抑制SR电动机的振动和噪声方案提供参考.     

热传导型半导体瞬态问题特征变网格有限元法及其分析

热传导型半导体器件的瞬时状态由四个方程的非线性偏微分方程组的初边值问题所决定，其中电子位势方程是椭圆型的，电子和空穴浓度方程是对流扩散型的，温度方程为热传导型的。本文提出解这类问题的特征变网格有限元法，并进行了理论分析，在一定条件下，得到了某种意义下的最佳L^2误差估计结果。     

热动力学问题的数值计算

 对含热传导的流体动力学方程组，用有限元方法进行数值求解。采用傅里叶热传导计算热流、用热流连续条件计算单元间接触面的温度、用三角形传热法计算体单元表面的热流，考虑各向同性弹塑性流体材料模型、三项式物态方程和导热系数与状态的相关性，给出了傅里叶热传导、接触传热、热应力应变效应、以及混合物冲击压缩特性等算例。对混合物冲击温度的数值模拟表明，小颗粒混合物在冲击压缩过程中，颗粒间的温度有差别、稍有波动，并随时间趋向于一致，以至热平衡。     

A Nonconforming Arbitrary Quadrilateral Finite Element Method for Approximating Maxwell's Equations

The main aim of this paper is to provide convergence analysis of Quasi-Wilson nonconforming finite element to Maxwell's equations under arbitrary quadrilateral meshes.The error estimates are derived,which are the same as those for conforming elements under conventional regular meshes.