不确定区间隶属度语言变量及其应用

基于不确定语言变量和区间模糊数,提出了不确定区间隶属度语言变量的概念,定义了不确定区间隶属度语言变量的运算规则、大小比较方法,给出了不确定区间隶属度语言变量的加权算术平均算子、加权几何平均算子及其相应性质,并将这些算子应用于属性权重确知且属性值以不确定区间隶属度语言变量形式给出的不确定多属性群决策问题中,通过示例验证了基于不确定区间隶属度语言变量信息的多属性群决策方法的有效性和可行性。     

模糊运算和模糊有限元静力控制方程的求解

根据模糊数的区间形式表达和区间运算的性质,给出了模糊数和模糊变量的运算规则.据此并依据区间有限元理论,提出了结构模糊有限元静力控制方程的几种求解方法.方法可根据输入模糊数的隶属函数,给出结构响应量的可能性分布.且计算量小,易于实施.算例分析说明了方法是实用和可行的.     

一种基于三参数区间灰色语言变量的多属性群决策方法

针对属性值为三参数区间灰色语言变量的不确定型多属性决策问题进行了研究,本文将语言变量和三参数区间数融合, 提出了三参数区间灰色语言变量的概念, 定义了三参数区间灰色语言变量的运算规则和可能度公式,在此基础上建立了基于投影模型的三参数区间灰色语言变量的多属性群决策方法。最后,通过对移动银行服务质量评估案例验证本模型的有效性。     

基于区间直觉模糊不确定语言变量的VIKOR方法及其在房地产开发风险评价中的应用

采用区间值直觉模糊不确定语言变量建模决策中存在的不确定信息,给出了一个新的不确定环境下的VIKOR方法.首先采用区间直觉模糊不确定语言变量对方案进行评价,然后将VIKOR方法进行推广到新的不确定环境下,给出新的方案排序方法.最后为了说明方法的有效性和合理性,将所给的方法应用于房地产开发方案的风险评价中.     

区间直觉不确定语言几何Heronian平均算子及其在多属性群决策中的应用

针对决策信息为区间直觉不确定语言变量且属性间存在相互关联的多属性群决策问题,提出了一种基于区间直觉不确定语言几何加权Heronian平均算子的决策方法.首先对区间直觉不确定语言变量的概念、运算法则以及相关性质等做出界定,然后基于区间直觉不确定语言变量和Heronian平均算子,定义了新的区间直觉不确定语言几何Heronian平均算子和区间直觉不确定语言几何加权Heronian平均算子,并给出了基于IVIULN的MAGDM方法,最后通过实例验证了该算子的科学性与适用性.     

四边简支正交异性板双向压屈模态的确定及其临界载荷的显式表达式

Libove曾经证明[1],四边简支的正交异性板在双向压力下的屈曲模态沿x方向和y方向的半波数m和n这两者中必有一者为1.本文将给出m=1或n=1的条件,并确定n=1时m的取值,及m=1时n的取值.从而完全确定了四边简支正交异性板在双向压力下的屈曲模态,并给出了临界载荷的显式表达式.     

区间有限元方法及其在抗滑稳定性分析中的应用

通过区间值函数和实值函数的关系探讨了区间相关性导致的区间扩张的问题,给出了保证区间计算获得足够精度的计算方法;提出了基于单元的子区间摄动有限元计算方法,并给出了提高计算效率的一些方法和获得较好计算精度时的子区间数目的近似计算公式．结合工程实例,基于单元的子区间有限元方法和抗滑稳定性分析方法给出了稳定性的区间范围,为更合理地估计和评价结构的抗滑稳定性提供一定的依据．     

区间数的绝对值与区间值函数的极限

研究了区间数的绝对值和区间值函数的极限问题.首先,讨论了区间数的H-差的性质,得到了H-差的两个运算法则;然后,给出了区间数的绝对值概念,并讨论了区间数绝对值的性质;最后,借助区间数的H-差和绝对值的概念,建立了区间值函数极限概念的一种新的表达方式,给出了极限存在的充分必要条件,证明了极限值的唯一性及对加法运算和数乘运算的封闭性.     

基于区间分析的投资组合VaR计算新方法

基于区间分析估计变量的累计概率分布是进行风险价值分析的一种新方法。本文将区间分析运用到股票投资组合的VaR计算中,研究区间分析在VaR计算方法中的应用。首先给出了基于区间分析估计分布函数的计算步骤,然后将区间分析运用到VaR的计算中,以两只股票的投资组合为例得出收益率的累计概率分布,从中得到某一置信度下的VaR值,最后与蒙特卡洛模拟方法做了比较研究,结果表明,基于区间分析的VaR计算方法的运算精度和计算速度明显优于蒙特卡洛模拟方法。     

区间值模糊推理

针对区间值模糊关系,讨论区间值模糊关系的合成运算及其运算性质,在此基础上研究简单区间值模糊推理和多重区间值模糊推理的两种模糊推理形式,给出4种区间值模糊推理的数学模型,并辅以实例来说明我们提出的区间值模糊推理方法的可行性。     

Time dependent uncertain free vibration analysis of composite CFST structure with spatially dependent creep effects

In this study, the time dependent free vibration analysis of composite concrete-filled steel tubular (CFST) arches with various uncertainties is thoroughly investigated within a non-stochastic framework. From the practical inspiration, both uncertain material properties and mercurial creep effect associated with such composite materials are simultaneously incorporated. Unlike traditional non-probabilistic schemes, both spatially independent (i.e., conventional interval models) and dependent (i.e., interval fields) interval system parameters can be comprised within a unified uncertain free vibration analysis framework for CFST arches. For the purpose of achieving a robust framework of the time-dependent uncertain free vibration analysis, a new computational approach, which has been developed within the scheme of the finite element method (FEM), has been proposed for determining the extreme bounds of the natural frequencies of practically motivated CFST arches. Consequently, by successfully solving two eigenvalue problems, the upper and lower bounds of the natural frequencies of such composite structures with various uncertainties can be rigorously secured. The unique advantage of the proposed approach is that it can be effectively integrated within commercial FEM software with preserved sharp bounds on natural frequencies for any interval field discretisation. The competence of the proposed computational analysis framework has been thoroughly demonstrated through investigations on both 2D and3D engineering structures.     

Time response of structure with interval and random parameters using a new hybrid uncertain analysis method

Practical structures often operate with some degree of uncertainties, and the uncertainties are often modelled as random parameters or interval parameters. For realistic predictions of the structures behaviour and performance, structure models should account for these uncertainties. This paper deals with time responses of engineering structures in the presence of random and/or interval uncertainties. Three uncertain structure models are introduced. The first one is random uncertain structure model with only random variables. The generalized polynomial chaos (PC) theory is applied to solve the random uncertain structure model. The second one is interval uncertain structure model with only interval variables. The Legendre metamodel (LM) method is presented to solve the interval uncertain structure model. The LM is based on Legendre polynomial expansion. The third one is hybrid uncertain structure model with both random and interval variables. The polynomial-chaos-Legendre-metamodel (PCLM) method is presented to solve the hybrid uncertain structure model. The PCLM is a combination of PC and LM. Three engineering examples are employed to demonstrate the effectiveness of the proposed methods. The uncertainties resulting from geometrical size, material properties or external loads are studied.     

基于区间数期望和不确定性分析的多属性决策方法与应用

针对区间数多属性决策中的不确定性问题,提出基于区间数的不确定性分析方法,用集对分析联系数中的A表示区间数的数学期望,Bi表示区间数的不确定性,借助联系数A+Bi的加、乘运算建立区间数多属性决策模型,再利用i的不同取值进行不确定性分析.实例应用表明,方法算理清晰,算法简明,分析方便,结论可靠.     

静力分析的一般随机摄动法

本文对向量值和矩阵值函数的不确定结构的静力响应和可靠性进行了研究。基于Ｋｒｏｎｅｃｋｅｒ代数和摄动理论导出了随机结构的有限元分析方法，随机变量和系统导数很方便地排列到２Ｄ矩阵中，给出了一般的数学表达式．     

Finite element method for two‐dimensional time‐fractional tricomi‐type equations

In this article, we consider the finite element method (FEM) for two‐dimensional linear time‐fractional Tricomi‐type equations, which is obtained from the standard two‐dimensional linear Tricomi‐type equation by replacing the first‐order time derivative with a fractional derivative (of order α, with 1 <α< 2 ). The method is based on finite element method for space and finite difference method for time. We prove that the method is unconditionally stable, and the error estimate is presented. The comparison of the FEM results with the exact solutions is made, and numerical experiments reveal that the FEM is very effective. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2013     

区间参数结构振动问题的矩阵摄动法

当结构的参数具有不确定性时，结构的固有频率也将具有某种程度的不确定性．本文讨论了区间参数结构的振动问题，将区间参数结构的特征值问题归结为两个不同的特征值问题来求解．提出了求解区间参数结构振动问题的矩阵摄动方法．数值运算结果表明，本文所提出方法具有运算量小，结果精度高等优点．     

基于区间的土体参数敏感性分析方法研究

将一种新的工程结构不确定性分析方法——区间分析方法溶入工程参数的敏感性分析之中,获得了一种新的工程参数敏感性分析方法,进一步拓宽了区间分析方法理论的应用领域．给出了土体参数敏感性因子矩阵求解的区间分析过程,依据区间分析给出了参数区间和决策目标区间的确定方法．基于MARC软件进行了二次开发,实现了Duncan-Chang非线性弹性模型以及与Fortran程序的相互调用功能．通过工程算例验证了该方法的合理可行性,并与文献的结果进行了对比．     

An adaptive algorithm in time domain for dynamic analysis of a simply supported beam subjected to a moving vehicle

This paper presents an adaptive algorithm in the time domain for the dynamic analysis of a simply supported beam subjected to the moving load and moving vehicle with/without varying surface roughness. By expanding variables at a discretized time interval, a coupled spatial‐temporal problem can be converted into a series of recursive space problems that are solved by finite element method (FEM), and a piecewised adaptive computing procedure can be carried out for different sizes of time steps. The proposed approach is numerically verified via the comparison with analytical and the Runge–Kutta method‐based solutions, and satisfactory results have been achieved. Copyright © 2011 John Wiley & Sons, Ltd.