Monte Carlo方法在可靠性分析中的应用

用MonteCarlo方法对事后可维修串联系统的可靠性进行了计算机模拟,讨论了元件的抽样方法,给出了事后维修的串联系统故障率与时间参数间的变化规律曲线。     

网絡协議TCP/IP

网络协议TCP/IP,分别相当于ISO/OSI参考模式中的第四层和第三层,源于美国国防部ARPANET的协议标准.目前,在高档微机工程工作站中得到广泛的应用,并成为工业界的一个“公认”标准. 本文介绍TCP/IP协议,并结合对B-NET(运行于16位微机DUAL系统83和UNIX系统V)中的TCP/IP的提取和分析,着重说明它们的接口及其执行过程机理.     

Dependent masking and system life data analysis: Bayesian inference for two-component systems

Data from field operations of a system is often used to estimate the reliability of components. Under ideal circumstances, this system field data contains the time to failure along with information on the exact component responsible for the system failure. However, in many cases, the exact component causing the failure of the system cannot be identified, and is considered to be masked. Previously developed models for estimation of component reliability from masked system life data have been based upon the assumption that masking occurs independently of the true cause of system failure. In this paper we develop a Bayesian methodology for estimating component reliabilities from masked system life data when the probability of masking is dependent upon the true cause of system failure. The Bayesian approach is illustrated for the case of a two-component system of exponentially distributed components.     

Some Bayesian lower bounds on reliability in the lognormal distribution

The two-parameter lognormal distribution with density function f(y: γ, σ²) = [(2πσ²)^1/2y] ¹exp[?(ln y ? γ)²/2σ²], y > 0, is important as a failure-time model in life testing. In this paper, Bayesian lower bounds for the reliability function R(t: γ, σ²) = ?[(γ ? ln t)/σ] are obtained for two cases. First, it is assumed that γ is known and σ² has either an inverted gamma or “general uniform” prior distribution. Then, for the case that both γ and σ² are unknown, the normal-gamma prior and Jeffreys' vague prior are considered. Some Monte Carlo simulations are given to indicate some of the properties of the Bayesian lower bounds.     

Gambling Screens: Does Shortening the Time Frame Affect their Psychometric Properties?

Gambling screening tools such as the South Oaks Gambling Screen (SOGS) and a DSM-IV Screen for Gambling Problems (NODS) developed by the National Opinion Research Council have psychometrically validated lifetime and past-year versions. As research questions often dictate shorter time intervals, researchers have adapted the time frames of these instruments to their specific purposes without examining whether changing the time frame affects the psychometric properties. In this study, 3-month versions of SOGS and NODS were administered to a sample of 80 pathological gamblers (59 men, 21 women, mean age 44) seeking treatment at a state-funded facility. The 3-months versions had good internal consistency, good convergent validity with each other, with gambling behaviors assessed via the timeline followback method, and with measures of impulsivity. The 3-month versions also showed good discriminant validity with demographic variables and a measure of verbal IQ. Together the data indicate that shortening the time frame to 3 months does not seem to have adverse effects on the psychometric properties of SOGS and NODS. Thus these adapted versions could profitably be used for shorter time intervals, including as pre/post-treatment and follow-up measures in treatment outcome studies.     

FMECA在遥控终端可靠性设计中的应用

概要论述了某型号遥控终端的故障模式、影响及危害性分析（ＦＭＥＣＡ），并指出如何根据ＦＭＥＣＡ的结果指导遥控终端可靠性设计     

社区教育视角下社区共同体意识的生成理路——基于四川省J县的社区教育实践

社区教育与社区治理具有高度耦合性,社区教育的资源性输入会形成社区治理的意识性输出。通过对四川省J县社区教育实践的分析,发现社区共同体意识的具体生成理路是：社区教育以知识生产、价值生产、情感生产、制度生产为依托,以利益生成为动力,以共识生成为旨归,通过社区教育的资源性输入建构了社区共同体的意识性输出链路。针对社区共同体意识生成中动态转化性较弱、横向传导性较差、纵向转化率较低的问题,需要从调适社区教育项目、建构关联点和提升关联密度、强化教育—实践和个体利益—社区利益微链路层面入手,实现输入—输出链路的优化。探究社区教育视角下社区共同体意识的生成理路,对于形塑社区教育与社区治理融合共生机制、促成社区教育与社区治理目标耦合、实现社区治理共建共商共享目标具有重要的理论价值和实践意义。     

A cold standby repairable system with the repairman having multiple vacations and operational,repair, and vacation times following phase-type distributions

ABSTRACT

This paper studies a cold standby repairable system with two identical components and one repairman having multiple vacations applying matrix-analytic methods. The lifetime of the component follows a phase-type distribution. The repair times and the vacation times of the repairman are governed by different phase-type distributions, respectively. For this system, the Markov process governing the system is constructed. The system is studied in a transient and stationary regime, the availability, the reliability, the rates of occurrence of the different types of failures, and the working probability of the repairman are calculated, respectively. A numerical application is performed to illustrate the calculations.     

Identifiability of distributions under competing risks and complementary risks model

Let X₁,X₂,…,X_p be p random variables with cdf's F₁(x),F₂(x),…,F_p(x)respectively. Let U = min(X₁,X₂,…,X_p) and V = max(X₁,X₂,…,X_p).In this paper we study the problem of uniquely determining and estimating the marginal distributions F₁,F₂,…,F_p given the distribution of U or of V.

First the problem of competing and complementary risks are introduced with examples and the corresponding identification problems are considered when the X₁'s are independently distributed and U(V) is identified, as well as the case when U(V) is not identified. The case when the X₁'s are dependent is considered next. Finally the problem of estimation is considered.