应力为MOBVE分布强度为指数分布下串联结构可靠度的估计

考虑了应力服从MOBVE分布,强度服从指数分布的应力——强度模型,分别在应力参数未知和强度参数未知情形下给出了该模型在串联系统下可靠度的估计并讨论了其性质.     

应力为GBVE分布强度为指数分布下结构可靠度的估计

本文考虑应力服从GBVE分布，强度服从指数分布的应力一强度模型，分别在应力参数未知和强度参数未知情形下给出了该模型可靠度的估计并讨论了其性质．     

应力为SGBVE分布强度为指数分布下结构可靠度的估计

考虑了应力服从SGBVE分布,强度服从指数分布的应力—强度模型,分别在应力参数未知和部分强度参数未知的情形下给出了该模型可靠度的估计,并讨论了其性质.     

应力服从一类嵌套多元指数分布的结构可靠度估计

本文研究应力服从一类嵌套多元指数分布, 强度服从指数分布的应力---强度结构可靠度模型.分别在强度参数未知、应力参数已知和强度参数已知、应力参数未知的情况下给出了结构可靠度$P_{A}$的估计$\wh{P}_{A1}$和$\wh{P}_{A2}$,并讨论了它们的渐近性质,而且获得了$P_{A}$的近似置信区间.最后对这两种情况下模型结构可靠度的估计$\wh{P}_{A1}$和$\wh{P}_{A2}$进行了随机模拟,随机模拟结果令人满意.     

关于半参数函数关系模型的渐近正态性

本文研究固定设计的半参数函数关系模型.利用权函数和广义最小二乘法得出未知参数和未知函数的估计,在一定的条件下证明了估计是强相合的,并且渐近地服从正态分布.     

关于半参数函数关系模型的渐近正态性

本文研究固定设计的半参数函数关系模型.利用权函数和广义最小二乘法得出未知参数和未知函数的估计,在一定的条件下证明了估计是强相合的,并且渐近地服从正态分布.     

Г─Г结构串联系统可靠度的Bayes估计

本文把含于结构系统中应力和强度含有的未知参数视为随机变量，利用Ｂａｙｅｓ方法讨论了当应力和强度均服从Г分布时结构串联系统可靠度θ＝Ｐ（Ｘ＞Ｙ）的估计问题，给出了θ的Ｂａｙｅｓ置信限。     

应力、强度均服从瑞利（Rayleigh）分布的可靠性分析

在应力—强度干涉模型中,当应力、强度均服从瑞利(Rayleigh)分布:R(x│β)={2βxexp[(-xβ2)],x00x<0,参数未知的情况下,讨论了在给定验前分布情况下的可靠性R=P(Y相似文献   

NBUE分布类应力-强度模型的概率上界

研究应力-强度模型的结构的可靠性分析,当元件应力变量分布属于NBUE类,强度变量服从指数分布,给出了应力-强度模型中概率的上界,由此讨论了n个元件组成系统的应力-强度模型概率上界.     

误差为NSD序列的广义线性模型的M估计的强相合性

研究了以NSD序列(negatively superadditive dependent)为误差的广义线性模型,得到了未知参数的M估计.在较弱的条件下,利用指数不等式、NSD序列加权和的强收敛性和Borel-Cantelli引理等证明了未知参数M估计的强相合性.此结果推广了独立误差和NSD误差的线性模型的相应结果.     

Prediction of fracture toughness of embrittled steels by means of the Small Punch Test

To characterise the randomly distributed strength and fracture toughness of brittle steels, many specimens have to be destroyed. Since the Small Punch Test (SPT) needs only little material, it is a well suited experiment, when only a small volume of material is available. In this study the cleavage fracture of a ferritic steel at low temperature was investigated using the Beremin model. The failure probability is described with a 2-parameter Weibull distribution in terms of the so-called Weibull stress, which is calculated using an elastic-plastic finite element stress analysis. While the transfer of Weibull parameters works well between similar geometries and loading conditions, it works bad in more general cases. Modifications of the Beremin model are necessary to overcome this problem. Recent publications consider a lower threshold value of the Weibull stress, which leads to a lower Weibull modulus and therefore to a stronger volume size effect of strength. The suitability of this approach to transfer cleavage fracture results from SPT to fracture mechanics specimens was investigated. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Testing some covariance structures under a growth curve model

This paper considers three types of problems: (i) the problem of independence of two sets, (ii) the problem of sphericity of the covariance matrix Σ, and (iii) the problem of intraclass model for the covariance matrix Σ, when the column vectors of X are independently distributed as multivariate normal with covariance matrix Σ and E(X) = BξA,A and B being given matrices and ξ and Σ being unknown. These problems are solved by the likelihood ratio test procedures under some restrictions on the models, and the null distributions of the test statistics are established.     

独立非同分布二元高斯三角阵最大值的渐近性及相关统计推断

考虑二元独立非同分布高斯随机向量三角阵列最大值分布的渐近性及相关统计推断.此高斯三角阵的第n列的第i个向量服从二元高斯分布,其相关系数为i/n的函数并单调连续.首先建立了此高斯三角阵最大值分布的一阶和二阶渐近展开式.其次,分析相关系数参数估计及估计量的渐近性质.最后,通过随机模拟说明了相关系数之参数估计的有效性,并将该二元非同分布三角阵列模型应用于实际数据,得到了满意的结果.     

A stress recovery procedure for solving geometrically non-linear problems in the mechanics of a deformable solid by the finite element method

A stress recovery procedure is presented for non-linear and linearized problems, based on the determination of the forces at the mesh points using a stiffness matrix obtained by the finite element method for the Lagrange variational equation written in the initial configuration using an asymmetric Piola–Kirchhoff stress tensor. Vectors of the forces reduced to the mesh points are constructed using the displacements at the mesh points found by solving this equation and for the known stiffness matrices of the elements. On the other hand, these forces at the mesh points are defined in terms of unknown forces distributed over the surface of an element and given shape functions. As a result, a system of Fredholm integral equations of the first kind is obtained, the solution of which gives these distributed forces. The values of the Piola–Kirchhoff stress tensor of the first kind at the mesh points are determined using the values found for the distributed forces on the surfaces of the finite element mesh (including at the mesh points) using the Cauchy relations for the initial configuration. The linearized representation of this tensor enables all the derivatives of the increment in the strain vector with respect to the coordinates to be found without invoking the operation of differentiation. The particular features of the use of the stress recovery procedure are demonstrated for a plane problem in the non-linear theory of elasticity.     

Unbiased Estimation for a Multivariate Exponential whose Components have a Common Shift

It is shown that for independent and identically distributed random vectors, for which the components are independent and exponentially distributed with a common shift, we can construct unbiased estimators of their density, derived from the Uniform Minimum Variance Unbiased Estimator (UMVUE) of their distribution function. As direct applications of the UMVUEs of the density functions we present a Chi-square goodness of fit test of the model, and give two tables of the UMVUEs of some commonly used functions of the unknown parameters of the multivariate exponential model considered in this paper.     

Bayesian estimation of system reliability in Brownian stress-strength models

A stress-strength system fails as soon as the applied stress,X, is at least as much as the strength,Y, of the system. Stress and strength are time-varying in many real-life systems but typical statistical models for stress-strength systems are static. In this article, the stress and strength processes are dynamically modeled as Brownian motions. The resulting stress-strength system is then governed by a time-homogeneous Markov process with an absorption barrier at O. Conjugate as well as non-informative priors are developed for the model parameters and Markov chain sampling methods are used for posterior inference of the reliability of the stress-strength system. A generalization of this model is described next where the different stress-strength systems are assumed to be exchangeable. The proposed Bayesian analyses are illustrated in two examples where we obtain posterior estimates as well as perform model checking by cross-validation.     

The linear theory of dislocations and disclinations in elastic shells

A stress state of a thin linearly elastic shell containing both isolated as well as continuously distributed dislocations and disclinations is considered using the classical Kirchhoff–Love model. A variational formulation of the problem of the equilibrium of both a multiply connected shell with Volterra dislocations as well as shells containing dislocations and disclinations distributed with a known density is given. The mathematical equivalence between the boundary-value problem of the stress state of a shell caused by distributed dislocations and disclinations and the boundary-value problem of the equilibrium of a shell under the action of specified distributed loads is established. A number of problems on dislocations and disclinations in a closed spherical shell is solved. The problem of infinitesimally deformations of a surface when there are distributed dislocations is formulated.