一类具有变号位势Kirchhoff型方程解的存在性

该文研究了一类带有变号位势非线性项的Kirchhoff型方程的Neumann边值问题.利用变分方法,首先对空间进行分解,证明了该问题的能量泛函满足山路结构;然后证明了能量泛函的(PS)序列有强收敛的子列;最后通过Ekeland变分原理和山路引理,获得了该问题两个非平凡解的存在性.     

嫦娥三号软着陆轨道设计与控制策略的优化模型

针对嫦娥三号软着陆轨道设计与控制策略问题,在合理假设的前提下,建立动力学模型,求解得到了嫦娥三号着陆准备轨道近月点和远月点的速度。针对软着陆过程的6个阶段,通过受力分析,建立了嫦娥三号运动的微分方程模型,以燃料消耗最小为优化目标,以每个阶段的起止状态为约束条件,将软着陆轨道的优化设计问题转化为主发动机推力的泛函极值问题,并将其控制函数转化为近似的多项式函数优化问题。运用四阶Runge-Kutta差分迭代方法进行求解计算,从而得到各个阶段的最优控制函数和控制策略。结果表明,嫦娥三号软着陆过程耗时695s,消耗燃料1 269.1kg。     

求二次比式和问题全局解的一个新的确定性算法

本文研究一类二次比式和规划问题.首先,利用等价转换的方法把原问题转化为一个非线性规划问题,并且这个非线性规划问题的目标函数通项的分子和分母都分别是两项线性函数乘积和再加上一个线性函数的形式,再根据两项线性函数乘积和的特性,对目标函数进行线性松弛,以确定原问题最优值的下界,从而提出一个求解线性规划问题的分支定界算法,并证明该算法的收敛性.最后,数值结果表明所提出的算法是可行有效的.     

一类模糊线性规划模型的模糊最优区间值

讨论一类既有模糊不等式约束又有模糊等式约束的全模糊系数线性规划问题。在给定的模糊隶属度水平下 ,将模型转化为区间数线性规划模型 ,通过确定区间模型的最佳目标函数和最大可行域以及最劣目标函数和最小可行域 ,求出目标函数的模糊最优区间值 ,从而为决策者提供更多的决策信息。最后给出一个数值例子。     

一类时滞方程的谱与解展开

该文研究一类时滞方程解的展开问题. 研究的模型来自于实际高精密切割过程中具有时间延迟的机床振动问题. 对此模型,借助于泛函分析方法,将其写成抽象发展方程. 对系统确定的算子给出了较细致的谱分析,得到本征值的渐近表达式.同时证明相应的本征向量不能构成状态空间基, 但给出方程解的展开式.     

向量值优化问题的适定性

将向量值优化问题的适定性理论推广到具有W-距离的拟度量空间中,给出B-适定性及DH-适定性的概念,并得到相应的判别准则．定义一类非线性标量化函数,利用这类标量化函数的性质将向量值优化问题转化为标量值优化问题,得到原问题与标量化问题的适定性之间的等价关系．     

用最小范数法解三峡梯级水电站短期经济调度问题

本文主要研究三峡梯级水电站与华中、华东和川东电网联网的短期经济调度问题,利用泛函分析和运筹学相结合的方法建立了三峡梯级水电站日负荷最优分配的数学模型。本文扩充和推广了Hawary和Christensen的最小范数法用来求解这个具有等式和不等式约束的高维非线性含时滞的动态最优化问题,最优策略由一组动态的非线性代数、微分方程确定。引入适当的变量并进行适当化简,最终可将三峡梯级水电系统的经济调度问题转化为一个最小范数问题,并给出了最优解的具体表达式.用Lagrange乘子和Kuhn-Tucker乘子将约束条件并入目标函数中形成一个增广价格函数。通过变换可将该无约束优化问题转化为求解非线性代数方程组的问题。本文选用Fletcher-Reeves共轭梯度法求解无约束极值问题.在IBM-PC型微机上进行了试算。试算结果表明用最小范数法求解三峡梯级水电站日负荷最优分配问题是完全可行的,梯级水耗率有明显下降,能获得一定的经济效益。     

最优绩效分配的多目标优化方法

如何体现某种程度的激励并兼顾公平性是绩效分配问题研究的关键之一. 基于考核对象的个体差异性, 对考核对象进行分类处理, 通过引入以体现激励程度的控制参数和所有考核对象的基础工作量为变量的分值转化函数与满意度函数, 建立以所有考核对象的总体满意度的最大化和考核对象的满意度尽可能均衡为目标的多目标优化模型. 进而利用多目标优化模型的epsilon-约束标量化方法证明了弱有效解的存在性. 作为其应用, 研究了某高校教师的最优绩效分配问题.     

复矩阵截断奇异值分解的一类混合算法

截断奇异值分解是一类非常重要的矩阵分解,其在病态模型问题分析等领域有广泛的应用.该文主要研究复矩阵截断奇异值分解的有效算法,将问题转化为复Stiefel乘积流形上的黎曼优化问题,进而设计基于乘积流形的黎曼混合牛顿法求解.为有效求解黎曼牛顿方程,从降低系统维数和简化计算入手,通过克罗内克积和复矩阵拉直算子将其转化为易于求解的标准实对称线性方程组.数值实验和数值比较验证该文所提算法针对复矩阵截断奇异值分解问题是高效可行的.     

一类非线性三层规划问题的罚函数方法

文章研究了一类结构为非线性-线性-线性三:层规划问题的求解方法.首先,基于下层问题的Karush-Kuhn-Tucker (K-K-T)最优性条件,将该类非线性三层规划问题转化为具有互补约束的非线性二层规划,同时将下层问题的互补约束作为罚项添加到上层目标;然后,再次利用下层问题的K-K-T最优性条件将非线性二层规划转化为非线性单层规划,并再次将得到的互补约束作为上层目标的罚项,构造了该类非线性三层规划问题的罚问题.通过对罚问题性质的分析,得到了该类非线性三层规划问题最优解的必要条件,并设计了罚函数算法.数值结果表明所设计的罚函数算法是可行、有效的.     

Linearly constrained global optimization via piecewise-linear approximation

This paper considers the problem of optimizing a continuous nonlinear objective function subject to linear constraints via a piecewise-linear approximation. A systematic approach is proposed, which uses a lattice piecewise-linear model to approximate the nonlinear objective function on a simplicial partition and determines an approximately globally optimal solution by solving a set of standard linear programs. The new approach is applicable to any continuous objective function rather than to separable ones only and could be useful to treat more complex nonlinear problems. A numerical example is given to illustrate the practicability.     

面向客户定制模式的供应链管理系统优化模型

建立供应链管理系统优化模型是构建高效率供应链以及发挥供应链优势的前提和基础 .本文建立了面向客户定制模式的集成的供应链管理系统优化模型 ,即一个多目标、具有约束的非线性混合规划模型 ,并提出了针对这种模型的求解思路 .通过对模型的仿真求解既可以优化选择供应链系统中涉及的相关协作企业 ,同时优化系统的订货、生产、库存策略 ,对构建高效率供应链管理系统具有重要意义 .     

Syst��mes hamiltoniens compl��tement int��grables

This article is dedicated to one of the greatest mathematicians of our time: V.I. Arnold, who died suddenly Thursday, June 3, 2010 in France. Integrable hamiltonian systems are nonlinear ordinary differential equations described by a hamiltonian function and possessing sufficiently many independent constants of motion in involution. The regular compact level manifolds defined by the intersection of the constants of motion are diffeomorphic to a real torus on which the motion is quasi-periodic as a consequence of the following purely differential geometric fact: a compact and connected n-dimensional manifold on which there exist n vector fields which commute and are independent at every point is diffeomorphic to an n-dimensional real torus and each vector field will define a linear flow there. We make a careful study of the connection with the concept of completely integrable systems and we apply the methods to several problems.     

Uniform stability of damped nonlinear vibrations of an elastic string

Here we are concerned about uniform stability of damped nonlinear transverse vibrations of an elastic string fixed at its two ends. The vibrations governed by nonlinear integro-differential equation of Kirchoff type, is shown to possess energy uniformly bounded by exponentially decaying function of time. The result is achieved by considering an energy-like Lyapunov functional for the system.     

EXISTENCE OF MINIMIZING SOLUTIONS AROUND ＂EXTENDED STATES＂ FOR A NONLINEARLY ELASTIC CLAMPED PLANE MEMBRANE

The formal asymptotic analysis of D. Fox, A. Raoult & J.C. Simo has justified the two-dimensional nonlinear “membrane“ equations for a plate made of a Saint Venant-Kirchhoffmaterial,     

EXISTENCE OF MINIMIZING SOLUTIONS AROUND ``EXTENDED STATES' FOR A NONLINEARLY ELASTIC CLAMPED PLANE MEMBRANE

The formal asymptotic analysis of D. Fox, A. Raoult $\&$ J.C. Simo$^{[10]}$ has justified the two-dimensional nonlinear ``membrane' equations for a plate made of a Saint Venant-Kirchhoff material. This model, which retains the material-frame indifference of the original three dimensional problem in the sense that its energy density is invariant under the rotations of $\R^3$, is equivalent to finding the critical points of a functional whose nonlinear part depends on the first fundamental form of the unknown deformed surface. The author establishes here, by the inverse function theorem, the existence of an injective solution to the clamped membrane problem around particular forces corresponding physically to an ``extension' of the membrane. Furthermore, it is proved that the solution found in this fashion is also the unique minimizer to the nonlinear membrane functional, which is not sequentially weakly lower semi-continuous.     

基于曲率插值的大变形梁单元

线性梁单元的形函数在单元大转动时会引起虚假应变,不适用于几何非线性分析．传统的几何非线性梁单元由于位移插值和转角插值的相干性,常常引起剪切闭锁等问题．该文 提出了一种平面大变形梁单元,通过单元域内的曲率插值以及曲率与节点位移之间的函数关系,将单元节点力和节点位移表示为节点曲率的函数．由于曲率插值本质上是对梁的应变进行插值,保证了单元任意刚体运动不会产生虚假的节点力;且将梁的截面形心位移表示为曲率的函数,避免了传统单元中的剪切闭锁问题．因而所提方法特别适用于梁的几何非线性分析．数值算例说明了所提方法的正确性和有效性.     

刚-柔耦合系统离心力效应模型及姿态机动稳定性

研究非线性离心力对刚-柔耦合系统的大范围姿态运动的影响．首先从离心力势场的概念出发,推导了刚-柔耦合系统的非线性模型;然后通过近似计算分析了非线性离心力对系统姿态运动的动态效应;最后,在只有系统姿态与姿态速率测量值的条件下,基于能量范数选择Liapunov函数,证明了采用PD反馈控制律能够确保大角度姿态机动过程的稳定性．     

Nonlinear Questions in Clamped Plate Models

The linear clamped plate boundary value problem is a classical model in mechanics. The underlying differential equation is elliptic and of fourth order. The latter is a peculiar feature with respect to which this equation differs from numerous equations in physics and engineering which are of second order. Concerning the clamped plate boundary value problem, “linear questions” may be considered as well understood. This changes completely as soon as one poses the simplest “nonlinear question”: What can be said about positivity preserving? Does a plate bend upwards when being pushed upwards? It is known that the answer is “no” in general. However, there are many positivity issues as e.g. “almost positivity” to be discussed. Boundary value problems for the “Willmore equation” are nonlinear counterparts for the linear clamped plate equation. The corresponding energy functional involves curvature integrals over the unknown surface. The Willmore equation is of interest in mechanics, membrane physics and, in particular, in differential geometry. Quite far reaching results were achieved concerning closed surfaces. As for boundary value problems, by far less is known. These will be discussed in symmetric situations. This survey article reports upon joint works with A. Dall’Acqua, K. Deckelnick (Magdeburg), S. Fröhlich (Free University of Berlin), F. Gazzola (Milan), F. Robert (Nice), Friedhelm Schieweck (Magdeburg) and G. Sweers (Cologne).