Free and forced convection boundary layer flow through a porous medium with large suction

An analytical study is made of the free and forced convection boundary layer flow past a porous medium bounded by a semi-infinite vertical porous plate. Locally similar solutions are then obtained by a perturbation method for large suction. Solutions for the velocity and temperature distributions are shown graphically for various suction velocities and values of the driving parameter G_r/R, where G_r is the Grashof number and R_e is the Reynolds number. The corresponding values of the skin friction coefficient and the Nusselt number are finally shown in tabular form.     

New gauss–seidel like block iterative methods to solve discrete boundary value problems

The concept of new Gauss–Seidel like iterative methods, which was introduced in [3], will be extended so as to obtain a class of convergent Gauss–Seidel like block iterative methods to solve linear matrix equations Ax=b with an M-Matrix A. New block iterative methods will be applied to finite difference approximations of the Laplace's equation on a square (“model problem” [8]) which surpass even the block successive overrelaxation iterative method with optimum relaxation factor in this example.     

Initial value methods for the primary two point boundary value problems in modeling viscoelastic flows

Initial value solvers through shooting methods will be used to compute solutions to the primary two-point boundary value problem arising in modeling viscoelastic flow. We will show that the classical Runge-Kutta methods will have at least h ²-order of convergence due to the presence of the singularity. Comparison with the work of others will also be presented through some numerical results and examples.     

顺序输送粘度差对混油量影响分析

针对两种不同粘度的后行柴油分别与同一种前行汽油顺序输送时存在的混油问题,借助CFD模拟仿真软件,建立了三维流动传质耦合模型。模拟计算结果表明,前行油品与后行油品的粘度差对顺序输送时的沿程混油量有显著影响。由横向混油截面的变化情况来看,混油初期后行柴油以弓形前锋曲面嵌入到前行油品中,运行30s其前锋曲面逐渐变尖且以锥形曲面向前行油品逐渐延伸;从纵向混油截面的变化情况来看,截面柴油以楔形前锋曲面从管道下部嵌入前行油品中;管道侧面、顶面和底面边界层区域的混油量均随粘度差的增大而减小,且底面边界层区域的混油量最大。     

基于解析法的裁剪PDE曲面的生成技术

为解决基于偏微分方程的曲面裁剪问题,研究一种广泛应用于偏微分方程曲面的裁剪方法.首先介绍基于偏微分方程的曲面生成方法,其次由参数域内的曲线在曲面上的投影,得到所求裁剪曲面的边界,然后利用解析法求得裁剪后的PDE曲面,最后列举一系列的实例来说明该裁剪方法的应用并且专门研究多个裁剪区域的问题.     

径向基函数网络与GIS/RS融合的UGB预测

针对城市空间增长特点,探究城市扩展的规律,研究城市增长边界的计算和预测模型,这对于城市的发展规划具有重要的意义。然而,在国内外,关于城市增长边界方面的研究较少,首次提出利用人工神经网络、地理信息系统和遥感相结合的技术建立具有复杂几何形状的城市增长边界模型。通过数值实验结果表明,模型对城市未来增长边界的计算和预测准确度达80%～84%,结果表示直观、真实,能够为当前精明增长模式下的城市用地规划工作提供决策参考。     

Degenerate scale for the analysis of circular thin plate using the boundary integral equation method and boundary element methods

In this paper, the degenerate scale for plate problem is studied. For the continuous model, we use the null-field integral equation, Fourier series and the series expansion in terms of degenerate kernel for fundamental solutions to examine the solvability of BIEM for circular thin plates. Any two of the four boundary integral equations in the plate formulation may be chosen. For the discrete model, the circulant is employed to determine the rank deficiency of the influence matrix. Both approaches, continuous and discrete models, lead to the same result of degenerate scale. We study the nonunique solution analytically for the circular plate and find degenerate scales. The similar properties of solvability condition between the membrane (Laplace) and plate (biharmonic) problems are also examined. The number of degenerate scales for the six boundary integral formulations is also determined. Tel.: 886-2-2462-2192-ext. 6140 or 6177     

A study of the optimal measurement placement for parameter identification of orthotropic composites by the boundary element method

This paper concentrates on the design of the optimal measurement placement for the parameter identification of two-dimensional orthotropic composites, which is modeled by the boundary element. From the analysis of the well-posedness of the parameter identification processes using the Levenberg–Marquardt method, a performance indicator and an estimation of the maximum bias of identified parameters are deduced. Based on these results, a method for selecting the optimal measurement placement is proposed. The validity of this method is illustrated by some numerical examples. These examples reveal that the measurement placement has significant influence on identification results. Furthermore, an iterative process of selecting measurement placement is suggested for practical implementation.     

基于不可分双正交小波的二维数据压缩方法

构造了一种新的不可分双正交的对称小波滤波器，该滤波器具有有理系数，其对应的小波函数具有四阶消失矩，尺度函数具有非常好的Hölder光滑性。同时提出了基于该滤波器进行数据重构时的边界延拓方法。使用SPIHT和SPECK两种算法的实验表明，该文构造的小波滤波器在二维数据压缩方面具有较好的效果。