Energy Decay for the Cauchy Problem of the Linear Wave Equation of Variable Coefficients with Dissipation

Decay of the energy for the Cauchy problem of the wave equation of variable coefficients with a dissipation is considered. It is shown that whether a dissipation can be localized near infinity depends on the curvature properties of a Riemannian metric given by the variable coefficients. In particular, some criteria on curvature of the Riemannian manifold for a dissipation to be localized are given.     

Energy Decay for the Cauchy Problem of the Linear Wave Equation of Variable Coeffcients with Dissipation

Decay of the energy for the Cauchy problem of the wave equation of variable coeffcients with a dissipation is considered.It is shown that whether a dissipation can be localized near infinity depends on the curvature properties of a Riemannian metric given by the variable coeffcients.In particular,some criteria on curvature of the Riemannian manifold for a dissipation to be localized are given.     

The Convergence Analysis of the Decomposition Method for the (1+1)-Parabolic Problem in Nonuniform Media

A modified Adomian decomposition method is used to find approximate solutions for the reaction diffusion convection equation in nonuniform medium, i.e., with space-dependent coefficients. In this approach, the solutions are found in the form of a convergent power series with easily computed components. Convergence analysis of modified Adomian series solution for a class of these type of PDEs is discussed.     

Three-Dimensional Variational Analysis of Composite Structures Using Bernstein Polynomial Approximations. Report 1

The paper overviews the previous 3D variational analysis approaches and the numerical results obtained with the use of piecewise polynomial splines. A recently developed 3D displacement-assumed variational analysis approach is also described, where the Bernstein approximation polynomials of arbitrary degree are used as the shape functions for a 3D hexahedral discrete element of a composite body.     

COBRA: A New Formulation of the Classic p-Median Location Problem

The p-median problem was first formulated as an integer-linear programming problem by ReVelle and Swain (1970) and further revised by Rosing, ReVelle and Rosing-Vogelaar (1979). These two forms have withstood the test of time, as they have been used by virtually everyone since then. We prove that a property associated with geographical proximity makes it possible to eliminate many of the model variables through a substitution process. This new substitution technique has resulted in the elimination of up to 60% of the variables needed in either of these classic model formulations.     

Dynamic Programming Formulation of the Redundancy Allocation Problem

Dynamic programming formulation for obtaining the optimum number of redundancies at each stage in a system is explained in detail. It is also emphasized and illustrated by examples, that the ‘summation’ form of functional equations, as suggested in the paper, provide a faster solution to an otherwise computationally voluminous method.     

Probabilistic Formulation of the Emergency Service Location Problem

The problem of locating emergency service facilities is studied under the assumption that the locations of incidents (accidents, fires, or customers) are random variables. The probability distribution for rectilinear travel time between a new facility location and the random location of the incident P _i is developed for the case of P _i being uniformly distributed over a rectangular region. The location problem is considered in a discrete space. A deterministic formulation is obtained and recognized to be a set cover problem. Probabilistic variation of the central facility location problem is also presented.An example and some computational experience are provided to emphasize the impact of the probabilistic formulation on the location decision.     

Postbuckling of Composite Airframe Structures: Closed-Form Approximate Solutions

In this contribution, the postbuckling behaviour of imperfect rectangular composite plates under compression is treated in a closed-form analytical manner. Based on rather simple shape functions for the postbuckling deflections and the plate imperfections, the requirement for compatibility of the membrane strains leads to an explicit solution for Airy's stress function. The equilibrium condition in the out-of-plane direction is not fulfilled explicitly, but rather in an integral sense using a Galerkin-type formulation, leading to an approximate closed-form solution for the postbuckling deflections. Eventually, rather simple closed-form approximate solutions for all postbuckling state-variables can be derived that can be used conveniently in engineering practice. The quality of the closed-form solution is established by comparison with the results of other authors. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A Mixed-Integer Goal-Programming Formulation of the Standard Flow-Shop Scheduling Problem

Until recently, the majority of models used to find an optimal sequence for the standard flow-shop problem were based on a single objective, typically makespan. In many applications, the practitioner may also want to consider other criteria simultaneously, such as mean flow-time or throughput time. As makespan and flow-time are equivalent criteria for optimizing machine idle-time and job idle-time, respectively, these additional criteria could be inherently considered as well. The effect of job idle-time, measuring in-process inventory, could be of particular importance.This paper presents an extension of an earlier model developed by the authors, formulating the generalized N job, M machine standard flow-shop problem as a mixed-integer goal-programming model. The formulation was empirically tested through a comparison of the generated optimal solutions to their mathematically derived counterparts. For this, a special flow-shop problem with certain permutation properties was selected. In addition, a randomly chosen problem was solved to show the general applicability of the derived formulation.The model allows the incorporation of the makespan as well as the mean flow-time criteria, instead of optimization being based on a single objective.     

A Complex Mode Method for Wind-Induced Responses of 6-Parameter Practical Viscoelastic Damping Energy Dissipation Structures Based on the Davenport Wind Speed Spectrum北大核心CSCD

针对六参数实用黏弹性阻尼耗能结构,基于Davenport风速谱系列响应问题进行了系统的研究.首先,利用六参数黏弹性阻尼器的微分型本构关系,建立了耗能结构基于Davenport风速谱激励下的运动方程;然后,运用复模态法将耗能结构的运动方程由二阶微分方程转化为一阶方程,获得了耗能结构系统对风振激励响应的频域解和功率谱密度函数表达式;最后,利用数学恒等式,基于随机振动理论获得了耗能结构系统在Davenport风速谱激励下的响应和阻尼器受力的解析解.该文方法不仅考虑了结构系统在风振激励作用下全振型展开的结果,表达式较现有结果更为简便,效率及精度更高,且适用于非经典阻尼结构.     

变厚度圆板大挠度理论的摄动法

本文用对两个小参数的摄动法,对于轴对称圆薄板大挠度问题,在板厚按指数规律变化、载荷为均布的情况下,求出了三级摄动解。所得摄动解在特殊情况下与精确解的比较表明结果是较为理想的。     

Inverse Problems of the Mechanics of Thin-Walled Composite Structures

New formulations and methods for the solution of the inverse problems of thin-walled layered and reinforced shells and plates are discussed. Rational projects with regard for the requirements of nonflexural deformations in layered structural members, the given deformability of particular surfaces, the realization of a strictly momentless state, an equally stressed reinforcement, and the breaking strength of the binder at the interfaces are investigated. A brief review of the known solutions to these problems is given, and solutions to some new problems are described.     

复合材料结构失效的模糊数学模型

本文讨论了复合材料结构失效的模糊性,提出了结构失效度的概念并建立了相应的结构失效度分析理论.     

Global Smooth Solutions to the Cauchy Problem of Nonlinear Thermoelastio Equations with Dissipation

This paper considers the Cauchy problem for the nonlinear thermoelastic equations with dissipation. By means of energy methods, under the reasonable assumptions in mechanics the global existence, uniqueness and the decay rates of smooth solutions are proved.