Equivalent Theorem of Hellinger-Reissner and Hu-Washizu Variational Principles

lintroductionIn1954,byso-calledtry-and-el.l.ormethodHull]deducedtheHu-Washizupl'inciple,whichplaysan.importantroleinthehistoryofvariation.In1964,ChienlZIsystematicallydiscussedtheLagrangemultipliermethod.Withthemethod,hesuccessfullydeducedHu-Washizuprinci…     

Equivalent theorem of Hellinger-Reissner and Hu-Washizu variational principles

The paper has proved that Hellinger-Reissner and Hu-Washizu variational principles are but equivalent principles in elasticity by following three ways: 1) Lagrange multiplier method. The paper points out that only a new independent variable can be introduced when one constraint equation has been eliminated by one Lagrange multiplier, which must be expressed as a function of the original variable(s) and/or the new introduced variable after identification. In using Lagrange multiplier method to deduce Hu-Washizu principle from the minimum potential energy principle, which has only one kind of independent variable namely displacement, by eliminating the constraint equations of stress-displacement relations, one can only obtain a principle with two kinds of variables namely displacement and stress; 2) involutory transformation, with such method Hu-Washizu variational principle can be deduce directly from the Hellinger-Reissner variational principle under the same variational constraints of stress-strain relation, and vice verse; 3)semi-inverse method, by which both of the above variational principles can be deduced from the minimum potential energy principle with the same variational constraints. So the three kinds of variational functions in Hu-Washizu variational principle are not independent to each other, the stress-strain relationships are still its constraint conditions.     

具有表面电极的二维压电力学的广义变分原理

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变分迭代法求解一个抛物型方程的反问题

变分迭代法已被应用于求解一类含有未知参数线性抛物型方程的反问题中,它通过Lagrange乘子求得未知参量的精确值.变分迭代法可以快速得到收敛于反问题精确解的收敛序列,从而得到精确解.为了说明该方法的有效性,给出了两个实例.     

损伤粘弹性梁-柱的广义变分原理

从损伤的粘弹性材料的卷积型本构关系出发,建立了在小变形下损伤粘弹性梁-柱的控制方程,提出了以卷积形式表示的损伤粘弹性梁-柱弯曲问题的泛函,并给出了损伤粘弹性梁-柱的广义变分原理.应用这个广义变分原理,可分别给出梁-柱位移和损伤满足的基本方程,以及相应的初始条件和边界条件.     

一类二次型条件极值的求解

从拉格朗日乘数法入手，讨论一类二次型的条件极值问题，给出了主要结果，并应用它求解多元函数条件极值问题．     

多元函数条件极值的计算举例

多元函数的条件极值有多种算法。该文以举例的方式,总结介绍多元函数条件极值的几种初等计算方法及拉格朗日乘数法。     

弹性力学中混合变量的能量原理

建立了弹性力学中混合变量的虚功原理和虚余功原理,混合变量的最小势能原理和最小余能原理,混合变量最小势能的广义原理和最小余能的广义原理。同时,应用混合变量的最小势能原理于计算一复杂边界条件矩形板的弯曲。     

解析条件极值

条件极值在国民生产中有广泛的应用,例如,布局问题,分派问题等等。一些特殊的条件极值问题,可以转化为极值问题;目标函数和约束条件均为线性,可用单纯形法求解;二次以上的条件极值,可用Lagrange乘子法;Lagrange乘子法在求解条件极值问题上有重要的应用。     

基于变域变分有限元的翼型气动设计

Designing airfoils according to given pressure (or velocity) distribution is one kind of free boundary problems. Free boundary condition can be coupled with the flow governing equations by variable-domain variational calculus, which makes it possible to calculate simultaneously the flow field and the free boundary. An accurate deduction of the variable-domain variational principles is taken herein to design airfoils in compressible and incompressible flows. Furthermore, two grid types (H and O) are used in the calculation with better results for the O-type grid. It is shown that convergence is accelerated and good results can be obtained even if the initial guessed airfoil shape is a triangle, demonstrating the strong adaptability of this method.     

Local curve fitting based Lagrange multiplier selection for Id-slice in multi-view video coding

The rate and distortion of Id-slice do not fit the globally linear relationship on a logarithmic scale. Lagrange multiplier selection methods based on the globally linear approximate relationship are neither efficient nor optimal for multi-view video coding (MVC). To improve the coding efficiency of MVC, a local curve fitting based Lagrange multiplier selection method is proposed in this paper, where Lagrange multipliers are selected according to the local slopes of the approximate curves. Experimental results showed that the proposed method improves the coding efficiency. Up to 2.5 dB gain was achieved at low bitrates.     

多元函数条件极值的充分条件及其应用

拉格朗日乘数法给出了多元函数条件极值的必要条件，本利用正定二次型理论证明多元函数条件极值的一个充分条件．并应用它求解多元函数条件极值问题．     

Walther Janous-Shandun不等式的又一个证明

将Walther Janous—Shandun不等式转化为了条件不等式，利用Lagrange乘数法得到了一个较简捷的证明．     

Local curve fitting based Lagrange multiplier selection for Id-slice in multi-view video coding

The rate and distortion of Id-slice do not fit the globally linear relationship on a logarithmic scale. Lagrange multiplier selection methods based on the globally linear approximate relationship are neither efficient nor optimal for multi-view video coding （MVC）. To improve the coding efficiency of MVC, a local curve fitting based Lagrange multiplier selection method is proposed in this paper, where Lagrange multipliers are selected according to the local slopes of the approximate curves. Experimental results showed that the proposed method improves the coding efficiency. Up to 2.5 dB gain was achieved at low bitrates.     

Jonson加权不等式的新证法

构造多元函数并利用Lagrange乘数法，求其最大或最小值．用这种特殊的方法与构思，使此问题的证明过程简洁、明快、易于接受．     

拟单调变分不等式组的强制性条件

引进了拟单调变分不等式组问题,把变分不等式问题推广到了变分不等式组问题,讨论了该拟单调变分不等式组具有非空无界解的强制性条件,建立强制性条件与变分不等式组问题解集的关系．     

一类广义多值向量变分不等式

研究了Hausdorff拓扑向量空间中一类广义多值向量变分不等式问题（GMVVIP）,把定义在凸集上的GMVVIP部分地推广到了非凸集并运用KKM定理得到了这类GMVVIP解的存在性定理．     

Hilbert空间中一类广义混合变分不等式组的广义f-投影算法

研究了Hilbert空间中一类广义混合变分不等式解的存在性.利用广义f-投影算子的性质以及不动点定理,构造了新的迭代公式,研究了这类迭代公式的收敛性,给出了所得的收敛结果是广义逆混合变分不等式的解.     

Banach空间中的广义集值变分包含和预解算子

研究了Banach空间的广义集值变分包含.首先指出了J U Jeong所著文章中的定理3.1是不成立的,然后借助预解算子技巧,建立了与广义变分包含相关的迭代算法,并给出了广义变分包含的迭代收敛定理,从而更正了该定理.     

非对称变分不等式的另一类非精确交替方向法

对一类非对称变分不等式问题提出了另一类非精确交替方向法，对其中一个子问题(线性变分不等式)的计算仅需要达到一个相对的精度，我们研究了迭代序列的若干性质，并证明了算法的收敛性。