Stress-Strength Structural Reliability Model with a Stochastic Strength Aging Deterioration Process

A stress-strength structural reliability model was proposed with a stochastic strength aging deterioration process. In structural engineering,the deterioration of structure's strength should be the total of the deterioration owing to continual wear, fatigue,corrosion,etc.,and the abrupt deterioration as a result of randomly variable loads. The deterioration of structure's strength should be influenced by both the internal deterioration owing to direct wear and the external deterioration due to randomly variable loads.Meanwhile,the load process was given as Poisson square wave process. The reliability was derived using stress-strength interference theory. In particular,the reliability was also given when random variables followed the normal distribution.

Estimation of the Stress-Strength Reliability for Exponentiated Pareto Distribution Using Median and Ranked Set Sampling Methods

In reliability analysis,the stress-strength model is often used to describe the life of a component which has a random strength(X)and is subjected to a random stress(Y).In this paper,we considered the problem of estimating the reliability𝑅𝑅=P[Y<X]when the distributions of both stress and strength are independent and follow exponentiated Pareto distribution.The maximum likelihood estimator of the stress strength reliability is calculated under simple random sample,ranked set sampling and median ranked set sampling methods.Four different reliability estimators under median ranked set sampling are derived.Two estimators are obtained when both strength and stress have an odd or an even set size.The two other estimators are obtained when the strength has an odd size and the stress has an even set size and vice versa.The performances of the suggested estimators are compared with their competitors under simple random sample via a simulation study.The simulation study revealed that the stress strength reliability estimates based on ranked set sampling and median ranked set sampling are more efficient than their competitors via simple random sample.In general,the stress strength reliability estimates based on median ranked set sampling are smaller than the corresponding estimates under ranked set sampling and simple random sample methods.Keywords:Stress-Strength model,ranked set sampling,median ranked set sampling,maximum likelihood estimation,mean square error.corresponding estimates under ranked set sampling and simple random sample methods.

Statistical Inference of Stress-Strength Model for Exponentiated Pareto Model with Censored Data

The reliability of a system is discussed when the strength of the system and the stress imposed on it are independent and non-identical exponentiated Pareto distributed random variables with progressively censored scheme.Different interval estimations are proposed.The interval estimations obtained are exact,approximate and bootstrap confidence intervals.Different methods and the corresponding confidence intervals are compared using Monte-Carlo simulations.Simulation results show that the confidence intervals(CIs)of exact and approximate methods are really better than those of the bootstrap method.

Improved Discrete Interval-Valued Stress-Strength Interference Model Based on Extended Universal Generating Function

In practical engineering,sometimes the probability density functions( PDFs) of stress and strength can not be exactly determined,or only limited experiment data are available. In these cases,the traditional stress-strength interference( SSI) model based on classical probabilistic approach can not be used to evaluate reliabilities of components. To solve this issue, the traditional universal generating function( UGF) is introduced and then it is extended to represent the discrete interval-valued random variable.Based on the extended UGF,an improved discrete interval-valued SSI model is proposed, which has higher calculation precision compared with the existing methods. Finally,an illustrative case is given to demonstrate the validity of the proposed model.

Reliability Assessment Method Based on Interference Variable for Stress-Strength Model

Stress-strength model is a basic and important tool for reliability analysis.There are few methods to assess the confidence limit of interference reliability when the distribution parameters of stress and strength are all unknown.A new assessment method of interference reliability is proposed and the estimates of the distribution parameters are accordingly given.The lower confidence limit of interference reliability with given confidence can be obtained with the method even though the parameters are all unknown.Simulation studies and an engineering application are conducted to validate the method,which suggest that the method provides precise estimates even for sample size of approximately.

Reliability Bounds based on Universal Generating Function and Discrete Stress-strength Interference Model

A method for estimating the component reliability is proposed when the probability density functions of stress and strength can not be exactly determined. For two groups of finite experimental data about the stress and strength, an interval statistics method is introduced. The processed results are formulated as two interval-valued random variables and are graphically represented component reliability are proposed based on the by using two histograms. The lower and upper bounds of universal generating function method and are calculated by solving two discrete stress-strength interference models. The graphical calculations of the proposed reliability bounds are presented through a numerical example and the confidence of the proposed reliability bounds is discussed to demonstrate the validity of the proposed method. It is showed that the proposed reliability bounds can undoubtedly bracket the real reliability value. The proposed method extends the exciting universal generating function method and can give an interval estimation of component reliability in the case of lake of sufficient experimental data. An application example is given to illustrate the proposed method

大学生创新活力问卷的编制

目的:编制适合我国大学生的创新活力问卷并检验其信效度。方法:以文献分析和对42个大学生创新创业团队的开放式调查为基础,构建大学生创新活力的理论结构模型,并参考国内外相关的创新活力模型与测评指标,编制大学生创新活力初始问卷。通过方便取样,对1526名大学生的测量结果进行项目分析和探索性因素分析,对1640名大学生的测量结果进行验证性因素分析及信效度检验。结果:问卷共39个条目,包括创新动力与行为活力、创新精神与情感活力、创新意识活力、创新个性活力、创新知识与能力活力5个因子,五因素模型拟合良好(RMSEA=0.067,SRMR=0.042,CFI=0.913,NFI=0.902,IFI=0.913)。总问卷及5个因子的内部一致性系数为0.91~0.98,分半信度为0.83~0.96,重测信度为0.74~0.81;总问卷及5个因子得分与主观活力量表(r=0.40~0.49)、创造性人格自陈量表(r=0.31~0.52)显著相关,5个因子的平均方差萃取(AVE)在0.60~0.70,组合信度(CR)在0.88~0.97。结论:大学生创新活力问卷具有较好的信度和效度,可用于大学生创新活力的测评。

二项指数2分布的应力强度模型的可靠性估计

本文讨论了当系统的强度和系统所受的应力服从独立的、不同的二项式指数2分布时系统的可靠性问题.采用了不同的方法来估计可靠性.在估计过程中使用了极大似然(ML)方法、基于Wilson-Hilferty(WH)的正态近似方法和贝叶斯方法.同时,基于正态近似方法、贝叶斯法和Bootstrap法(Boot-p和Boot-t)提出了应力–强度可靠度的置信区间.通过蒙特卡罗模拟比较了不同的方法和相应的置信区间.最后,给出了一个真实数据集的分析进行说明.

Maintenance Strategy of Multi-Component System Due to Degradation and Shock

The proposed maintenance strategy uses component grades and survival signature to describe and update system structure. A system dynamic stress-strength reliability(SSR) model was established to describe component failure processes because of internal degradation and external shock. Besides, a corrective maintenance rule and two-level preventive maintenance rule made up the proposed maintenance strategy. The former combined sequentially minimal repair and corrective replacement(SMRCR) based on system structure updating. The latter considered group importance measure based on the system dynamic SSR and preventive maintenance cost. Further, a cost model was developed by the proposed strategy, and the optimal decision variables were found by genetic algorithm. Finally, using a case system to illustrate the above strategy improved system and reduced maintenance costs.

Reliability of a Multicomponent Stress-strength Model Based on a Bivariate Kumaraswamy Distribution with Censored Data

In this paper,we consider a system which has k statistically independent and identically distributed strength components and each component is constructed by a pair of statistically dependent elements with doubly type-II censored scheme.These elements(X1,Y1),(X2,Y2),…,(Xk,Yk)follow a bivariate Kumaraswamy distribution and each element is exposed to a common random stress T which follows a Kumaraswamy distribution.The system is regarded as operating only if at least s out of k(1≤s≤k)strength variables exceed the random stress.The multicomponent reliability of the system is given by Rs,k=P(at least s of the(Z1,…,Zk)exceed T)where Zi=min(Xi,Yi),i=1,…,k.The Bayes estimates of Rs,k have been developed by using the Markov Chain Monte Carlo methods due to the lack of explicit forms.The uniformly minimum variance unbiased and exact Bayes estimates of Rs,k are obtained analytically when the common second shape parameter is known.The asymptotic confidence interval and the highest probability density credible interval are constructed for Rs,k.The reliability estimators are compared by using the estimated risks through Monte Carlo simulations.

薄栅介质TDDB效应

在恒压和恒流应力条件下测试了超薄栅氧化层的击穿特性 ,研究了 TDDB(Tim e Dependent DielectricBreakdown)的可靠性表征方法 .对相关击穿电荷量 QBD进行了实验测试和分析 .结果表明 :相关击穿电荷量 QBD除了与氧化层质量有关外 ,还与应力电压和应力电流密度以及栅氧化层面积有关 .对相关系数进行了拟合 ,给出了 QBD的解析表达式 .按照上述表达式外推的结果和实验值取得了很好的一致 .提出了薄栅介质

大数据在管道安全评估中的应用

根据大数据的基本理论,提出管道数据化以及管道数据挖掘的概念,并给出了基于大数据管道安全评估的模式,为初步判断管道的安全性能提供了理论基础,同时介绍了基于大数据的管道可靠性评估方法,最后通过算例分析某管道的可靠性得到该管道的最大输送压力。

81枪族击发机可靠性分析及结构改进

可靠性是评价武器系统性能优劣的重要指标之一,通过对81枪族击发机的可靠性进行综合分析,提出了机构工作安全保险的概念,并认为81枪族击发机在结构设计上缺少机构工作安全保险中的零件位置不正确保险,存在事故隐患。针对这一情况,提出了对击发机结构的改进方案,并应用AUOTCAD软件进行计算机模拟,得出改进后的扳机限制突笋高度值,通过试验验证,改进后的击发机工作可靠性提高,且不影响枪械其它各动作的顺利进行。

有优先权两部件冷贮备可修系统的模糊可靠性

在开关不完全可靠的情况下,利用普通可靠性和模糊可靠性的基础理论,建立了有优先权两部件冷贮备Markov可修系统的模糊可靠性数学模型。利用模糊数学的原理和方法以及Laplace变换推导出该模型的一些模糊可靠性指标,并给出算例分析。比较其结果与传统可靠性理论的不同之处可知,模糊可靠性理论全面阐释了系统的可靠性行为。

线性化极限状态方程及归一型算法

对β通常的几何涵义进行了补充说明;讨论分析了几种可靠度计算中常用的线性化极限状态方程的迭代法,导出了几种方法基本方程间的关系。在迭代算法中,收敛性不仅决定着计算量的大小,而且决定着算法的可行性。在分析各种算法的收敛性之后,针对这些算法存在的问题提出了计算可靠指标β的归一型迭代法,并给出了两点迭代格式的迭代步骤。这个算法可以同时计算设计验算点。通过计算实例比较了几种算法的计算量和计算效果。结果表明,归一型算法计算速度快、计算量小,是一种实用的算法。

一类可靠性双环网络的容错分析

本文简述了双环网络的最新发展,分析了跳跃距离为[N^(1/2)]的前向环后向跳双环网络在多条弧中断的情况下网络出现故障的概率,建立了网络可靠性、平均故障时间以及在1～3个节点故障后网络通信率的数学模型.

直升机可靠性关键件和重要件的确定方法及工程应用

本文论述了可靠性关键件和重要件的确定目的,指出了当前型号设计中存在的问题,之后较详细地阐述了可靠性关键件和重要件的判别准则及决断程序,并以工程实例说明具体应用。

机械系统可靠性评定方法

本文根据数理统计原理和系统信息熵原理，针对复杂机械系统，提出一种适用于其可靠性评定的信息熵法。该方法是将部件的试验数据折合成系统的试验数据，作为系统试验的验前信息，而由二项式分布求任意置信度下的系统可靠度下限。计算方法简单实用，是复杂机械系统可靠性评定的较优方法。

测量平差可靠性研究

讨论了粗差与残差间的关系,在此基础上研究了测量平差系统内可靠性和外可靠性理论。并应用两个具体的算例说明了可靠性数值的解算过程。

服从对数正态分布的构结疲劳寿命可靠度计算方法

基于已有的实验结果，应用Ｍｉｎｅｒ线性累积损伤法则推导了在多级载荷作用下，疲劳寿命统计参数的精确计算公式，考虑了材料热处理、结构尺寸以及外载荷的分散性对结构疲劳寿命统计参数的影响，所推导公式计算结果与实验吻合较好。给出了结构连接件在复合应力作用下多模式疲劳寿命的线性安全边界方程，因方程中所包含的变量被转化成了正态分布的变量，故所算得的每个模式的可靠度是精确的。对结构体系的破坏概率随寿命相关系数变化的规律亦进行了研究。