查询词典 difference boundary value problem

Both the Dirichlet boundary conditions and the Neumann boundary condition are considered.

分Dirichlet和Neumann两种边值条件进行了讨论。

By using the spatial finite sine and cosine transform, and the temporal Laplace transform, the existence of the analytic solutions of its initial-boundary problems in a boundedspace domain with Dirichlet and Neumann boundary conditions is derived.

利用空间有限的sine或cosine变换及时间Laplace变换，给出了该方程有限区间上带Dirichlet和Neumann边界条件的两类初边值问题的解析解。

Compared with the same wave problems with conventional Dirichlet boundary conditions, the absorbing boundary conditions can reduce the numerical reflection on boundaries and avoid solution distortion. In addition, the central differences method is economic in memory requirement and computing time compared with implicit integral method.

结果表明：该解法在空间上具有谱精度，在时间上达到二阶精度；与第一类边界条件相比，吸收边界有效地削弱了边界上的数值反射，避免了解的失真；使用中心差分的时间积分方法同隐式积分方法相比，适合波的传播特性，避免了矩阵求逆运算，并且占用的计算机内存小。

The method involves an iterative procedure, which incrementally flattens a 3D triangular mesh by region growing and obtains a parameterization with free boundary. The result is then converted to a parameterization with regular boundary by conformal mapping. Our method accounts for both the angle and area distortion during parameterization, it yields a parameterization with less global distortion and no triangular flipping.

采用区域增长算法逐层展平空间三角网格，得到空间三角网格曲面的自由边界的参数化结果，并利用保形变换将自由边界的参数化结果变换为规则边界的参数化结果；同时兼顾了参数化的角度变形和面积变形，使得参数化结果具有整体变形较小的特点，并能够避免三角形折叠的现象。

It is concluded that the inversion of unknown boundary data is more effective when the Cauchy data are given more precisely and are distributed on the whole boundary more diversely.

由数值的结论，我们认为只要柯西资料给定的越准确，并且在全边界上给定的越分散，则会有越好的结果。

In this thesis, the virtual boundary integral equation is based on double layer potential with the virtual density to be determined on virtual boundary. Since this integral equation related to double layer potential only involves the computation of the normal derivative and second normal derivative of fundamental solution, the exponential integral function is not involved in it, so numerical computation for the exponential integral function is avoid.

本文则基于双层位势，引入虚拟矩密度函数来建立虚边界积分方程，并首先对时间变量进行解析积分，在虚、实边界上采用常单元和等额配点离散，该方程只涉及含基本解的法向导数及其二阶法向导数项的计算，对时间变量进行解析积分后，不会出现对指数积分函数的空间变量的积分计算。

According to the boundary relations of the electromagnetic field, and based on the phenomena of double refraction and double reflection in crystals, the reflectivity and transmissivity are deduced at boundary when an extraordinary beam is incident from an isotropic medium upon a crystal or from a crystal to an isotropic medium with optical ax.

为分析非常偏振光在晶体表面的能量损耗，给出一种求解反射率和透射率的方法，即根据电磁场的边值关系以及晶体的双折射和双反射现象，求解晶体光轴在入射面内时，非常偏振光从各向同性介质入射到晶体和从晶体出射到各向同性介质两种情况的反射率和透射率的方法，并给出反射率和透射率的解析解，同时得到对于晶体光轴在入射面内的情况，光轴的取向对非常偏振光反射率的大小几乎没有影响，但对产生全反射的临界角θc影响较大的结论。

In this paper, the boundary integration equations of contact problems are given according to the elastic-plastic and boundary elem...

本文根据弹塑性理论和边界元法理论推导出弹塑性接触问题的边界积分方程，给出多种接触问题研究方法、求解规则及相应的计算程序。

Chapter 2 and Chapter 3 of this dissertation,we discussoptimal boundary control problems for a semilinear elliptic type equation with linearboundary condition and nonlinear boundary condition,respectively.

全文共分为三部分内容：在第一部分即本文的第二章和第三章中，我们分别讨论了带有线性边界条件以及非线性边界条件的半线性椭圆型方程的最优边界控制问题。

It reduces a boundary valueproblem of elliptic equation to a singular integral equation on the boundary containing the finitepart of divergent integrals in the sense of distrib...

本文是在导师冯康教授指导下完成的，作者谨在此对他表示衷心的感谢。

For the head-teacher of the class said that I had seriously broken the school rules,which led me to a three-day suspend class.

为什么呢？因为我的班主任说我严重的违反了校规，于是让我停课三天。

Many of them believe that the conversion of thousands of working-class folk in England spared that nation from the mass carnage and the tyranny that came with the revolution in France.

他们之中有许多人相信，在英国数以千计的劳工阶级之悔改信主使英国免於遭受如法国大革命所造成的大屠杀和专制暴政。