变分问题

In Chapter 2,a steady permeability identification problem in elliptic equa-tions for two-dimensional orthotropic medium is considered.We construct afunctional,obtain its first and second Gateaux differential,and prove that thefunctional is strictly convex on a convex admissible function set.We seek to iden-tify the permeability by minimization of the above functional.

第二章研究了二维稳态正交异性介质的渗透率反演问题，我们构造了一个泛函，求得该泛函的一、二阶Gateaux微分，证明了它在一个凸的容许集上的严格凸性，并使用极小化泛函即变分方法来求解此问题。

Based on the laminate theory, a laminate weakened by damage is treated as an anisotropic thin plate. Using the complex potential method in the plane theory of elasticity of an anisotropic body, the series solution of finite anisotropic thin plate containing an elliptical inclusion is proposed with the help of Faber series. A hybrid element with an elliptical inclusion for anisotropic materials is obtained by using the hybrid variable principle, and the element efficiency is verified by numerical examples. The state of the damage is modeled by an elliptical soft inclusion, and using the point stress criterion based on characteristic curve and Yamada-Sun etc. criteria, the prediction of the strength of a composite laminate with damage is set up. The effects of various parameters on the stress distribution and the residual strength of a composite laminate weakened by damage are detailedly studied.

首先基于经典层板理论，将复合材料层板的弹性问题化归为均匀各向异性板来求解；采用各向异性体平面弹性理论中的复势方法，以Faber级数为工具，给出了有限大含椭圆核各向异性板弹性问题的级数解形式；利用杂交变分原理，成功导出含椭圆核各向异性板杂交应力有限元，并用算例验证了该单元的可行性和有效性；采用含刚度折减椭圆形弹性核的冲击损伤模型，引入基于特征曲线和Yamada-Sun破坏准则的点应力判据，建立了含损伤复合材料层板剩余强度的分析方法；通过数值计算详细讨论了各种几何参数对损伤层板应力分布、剩余强度的影响，得到了一系列对工程应用具有实用价值的结论。

Spectral element methods for partial differencial equation is introduced in this study from viewpoint of the collocation approximation of Chebyshev polynomial. Wave Equation and its space discretization are deduced. Two time integral methods, central difference method and implicit Newmark method, are introduced, and their stability and applicability are also discussed in some details. The significance of absorbing boundary conditions in spectral element methods for Aeroacoustics is explained, and Clayton-Engquist-Majda absorbing boundary conditions is emphasized and introduced, then the discrete scheme of this boundary conditions is deduced and applied to spectral element methods for wave equation.

本文从Chebyshev多项式逼近理论出发，详细介绍了谱元方法求解偏微分方程的过程；推导了流体中的声波动方程并在空间上对其进行了谱元离散；详细讨论了两种时间积分方法──中心差分法和Newmark方法，分析了它们的稳定性条件，并从理论上对比了两种方法的优缺点和适用范围；将吸收边界条件推广应用于谱元方法求解气动声学问题中，重点介绍了Clayton-Engquist-Majda吸收边界条件的原理和公式，推导了该吸收边界条件的变分形式，并将其引入波动方程的离散形式中。

The aim of this paper is to study the existence of solution and multiply results for quasilinear elliptic system in bounded domain and the whole space, semilinear elliptic equation in two dimension space, second order nonlinear difference equation by variational methods. The main results are listed in the following:1. An abstract compactness theorem is proved, and then, under weak Boccardo and De.

本文主要利用变分法，分别研究了有界区域和全空间上拟线性椭圆型方程组、二维空间上半线性椭圆型方程和二阶非线性差分方程问题的解与多重解的存在性，具体内容如下： 1。

The Neumann boundary value prob-lem is firstly reduced into the equivalent natural boundary integral equation withthe kernel possessing 2nd-order singularity,and then the corresponding variationalproblem on the boundary is obtained.By applying Quak trigonometric wavelet basisBjsee(1.2.3as boundary elements and the method of expanding kernel functionto its Galerkin discretization,we obtain simple computational formulae of the en-tries in the stiffness matrix.

首先，我们将Neumann边值问题归化为等价的带有2阶强奇性核的自然边界积分方程，然后化为边界上相应的变分形式，以Hermite插值Quak三角小波基Bj见(1.2.3作为边界元并利用积分核函数展开法将其离散，得到了十分简单的刚度矩阵系数的计算公式，而且刚度矩阵具有十分简单的形式，它是分块循环对角阵。

The way to use PMP to solve problem is a kind of sifting method:"If the control isreally an optimum one,then under the conditions stated beforehand,the needle variationmust not cause the index to have negative variation."

Pontryagin的最大值原理解决实际问题是筛选的方法："即如果是最优控制，那么其在满足约束条件的前提下，必须有进行针状变分不会造成指标泛函的变分为正。"

We estab-lish,under some mild assumptions,a locally quadratic convergence theoremfor Method I and prove a semi-local convergence theorem for Method II.Applications of the two methods to complementarity,variational inequalityand optimization problems are investigated as well.

在某些适当的假设下，我们证明了方法I的局部二次收敛性和方法II的半局部收敛性；还研究了两个方法在求解互补问题，变分不等式问题及约束优化问题中的应用。

In the chapter 2, based on elastic mechanics and variation principle, the fundamental and process of static and dynamic FEM is presented, placing special emphasis on the modal superposition method.

第二章根据弹性力学和变分原理，系统总结了有限元法求解静力学、动力学问题(包括特征值、动力响应问题等)的基本原理和步骤，并重点对模态叠加法求解动力，响应问题作了阐述。

In order to solve the traveler route and departure time choice problem under multiple transportation modes,the variational inequality formulation is proposed in modeling the traveler stochastic dynamic simultaneous route and departure time choice behaviors with elastic demand .

为了解决在多种交通模式条件下出行者的路径与出发时间选择问题，提出了一个变分不等式模型用于模拟具有变需求的多模式随机动态出行选择行为。

In this dissertation, two problems in the variational inequality theory are mainly considered: the existence of solutions and the approximation schemes.

本文主要讨论了变分不等式理论中的两个方面的问题：解的存在性问题以及解的逼近问题。

But we don't care about Battlegrounds.

但我们并不在乎沙场中的显露。

Ah! don't mention it, the butcher's shop is a horror.

啊！不用提了。提到肉，真是糟透了。