查询词典 dirichlet conditions

In this paper,we consider the existence and uniquness of solution for Dirichlet problem of the Helmholtz equation on the domain with corners, i.e problemFor smooth boundary,we use potential theory to transform the problem into second kind boundary integral equation ,and use Fredholm alternative theorem,we obtain the existence and uniqueness of Dirichlet problem.

在本文中，我们考虑边界含尖点的有界区域上Helmholtz方程△u+k~2u=0的Dirichlet问题即问题与问题解的存在及唯一性。

This paper first Studies the relation between coefficients and the growth of Dirichlit se-ries of zero order in the whole plane,and further proves that the growth of random entire functions defined by random Dirichlet series of zero order in every horizotal straight lines is almost surely equal tothe growth of entire functions defined by its corresponding Dirichlet series.

首先研究了全平面上零级狄里克莱级数的系数和增长性之间的关系，然后证明了对于本级随机狄里克莱级数所确定的随机整函数，在每条水平直线上的增长性几乎必然

To all project practicality, the introduction is given to the operational characteristics, the methods for calculation and the researching actuality of the tail tunnels with sloping ceiling underground hydropower stations the Three Gorges. This paper has discussed in detail the characteristic method being the same with the compressive flow and the Priessmann solution being the same with the free-surface-pressure flow. And how to deal with boundary conditions has been expatiated. Also hydraulic transient process of tremendous load fluctuation in the tail tunnels with sloping ceiling has been numerical simulated and the Fortran program for numerical simulation has been given. The paper gain the maximal press for tail end of the shell, the maximal rising rate of rotational speed of generating set, the maximal vacuum degree for inlet of the tail tunnels and so on under 11 kinds conditions of tremendous load fluctuation. These conditions include the design conditions, the check conditions and the superposition conditions. Finally, the computing results have been analyzed and summarized. The end chapter is the general comment of the whole-length content and the describing of the intending view of researching.

本文以三峡右岸地下电站尾水洞设计为背景，从工程实际出发，阐述了变顶高尾水洞的工作特性、使用范围及其研究现状；详细论述了适用有压流的特征线法、适用明满交替流的普里斯曼解法等数学模型；边界条件的给定和明满交替流的计算方法；用Fonran语言编制了数值计算程序，对三峡右岸地下电站变顶高尾水洞的大波动工况进行了数值模拟，分别得出了在设计工况、校核工况和叠加工况下蜗壳末端最大压力上升值、机组最大转速上升值和尾水管进口最大真空度等重要参数；对数值计算结果进行了详细分析并得出了有价值的结论；最后展望了今后水电站变顶高尾水洞的研究方向。

When there are diffusion effects and Dirichlet boundary conditions, we firstly obtain the conditions such that the system exists positive equilibrium solutions and give the asymptotic expression of these positive equilibrium solutions.

在具有扩散影响和Dirichlet边界条件时，首先利用隐含数定理获得了系统存在正平衡解的条件和正平衡解的渐近表达式。

The boundary conditions are assumed to be either the Dirichlet condition or linear Robin conditions.

在第一章，我们应用上、下解方法，bootstrap技巧和Schauder不动点定理考察如下三类周期反应扩散方程组的周期稳态解的存在性和一般的时变解的渐近性态：（1）拟单增系统；（2）混拟单调系统；（3）一个非拟单调2-系统，其边界条件是Dirichlet条件或线性Robin条件。

In chapter 4 and chapter 5, the Dirichlet transmission conditions for overlapping Schwarz methods will be replaced by Robin transmission conditions when applied to general linear elliptic partial differential equations.

为了能够直接应用于某些实际问题，本文第六章把最优Robin参数的确定方法推广到由椭圆型问题离散化得到的稀疏矩阵问题。

In Chapter 1, we use the upper and lower solutions method, the bootstrap technique and the Schauder fixed point theorem to investigate the existence of periodic solutions and the asymptotic behavior of general time-dependent solutions for periodic reaction-diffusion systems of the following three types:(1) Quasimonotone nondecreasing system;(2) Mixed quasimonotone system;(3) A nonquasimonotone 2-system. The boundary conditions are assumed to be either the Dirichlet condition or linear Robin conditions.

在第一章，我们应用上、下解方法，bootstrap技巧和Schauder不动点定理考察如下三类周期反应扩散方程组的周期稳态解的存在性和一般的时变解的渐近性态：（1）拟单增系统；（2）混拟单调系统；（3）一个非拟单调2-系统，其边界条件是Dirichlet条件或线性Robin条件。

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。

Apparently, the approximate controllability doesn"t hold for generally linear parabolic equations with bounded control. It doesn"t hold for the semilinear heat equations presented there,either. Then, it is proved by analyzing its" solutions that no matter how long the time T is , there are targets that can"t be approximated by the solution of heat equation with Dirichlet boundary conditions;If a given target satisying certain conditions can be reached by the solution of heat equation .

本文先针对两个具体的半线性热方程系统证明了控制加约束后系统是不能控的；然后通过分析方程的解，对带位势及Dirichlet边界条件的热方程系统，无论时间多大，都存在不能控的目标；文中还证明了满足一定条件的目标可达。

The classical overlapping Schwarz methods try to transport boundary information by exchanging message on the artificial boundaries. However because of taking Dirichlet conditions as the transmission conditions, which makes the solution reflect when across the artificial boundaries, classical overlapping Schwarz methods converge very slowly—suppose the overlapping domains take a little percentage.

人们很早就认识到，在Schwarz方法中可以采用其它的内边界条件—如Robin条件来代替Dirichlet内边界条件，而且也注意到如果参数选取合适，那么这些内边界条件可以大大加快Schwarz方法的收敛速度。

In the days of sailing vessels the crew were afraid they would be becalmed on the ocean.

在使用帆船的时代，船员们担心他们会因为无风而无法在海洋上航行。

As long as foreign donors pay the PA's salary bill, few expect a new intifada.

只要外国继续为巴权力机构的薪水买单，希望发动新暴动的人便寥寥无几。