A nonparametric approach to accelerated life testing under multiple stresses

Accelerated life testing (ALT) is concerned with subjecting items to a series of stresses at several levels higher than those experienced under normal conditions so as to obtain the lifetime distribution of items under normal levels. A parametric approach to this problem requires two assumptions. First, the lifetime of an item is assumed to have the same distribution under all stress levels, that is, a change of stress level does not change the shape of the life distribution but changes only its scale. Second, a functional relationship is assumed between the parameters of the life distribution and the accelerating stresses. A nonparametric approach, on the other hand, assumes a functional relationship between the life distribution functions at the accelerated and nonaccelerated stress levels without making any assumptions on the forms of the distribution functions. In this paper, we treat the problem nonparametrically. In particular, we extend the methods of Shaked, Zimmer, and Ball [7] and Strelec and Viertl [8] and develop a nonparametric estimation procedure for a version of the generalized Arrhenius model with two stress variables assuming a linear acceleration function. We obtain consistent estimates as well as confidence intervals of the parameters of the life distribution under normal stress level and compare our nonparametric method with parametric methods assuming exponential, Weibull and lognormal life distributions using both real life and simulated data. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 629–644, 1998     

Web站点负载测试方法研究

目前,随着网站数目的增多,网络用户也在急剧增加,因而对网站性能也提出了新的要求。针对Web站点提出相应的负载测试方法。通过该方法的使用,可以极大提高系统的性能、服务质量及可靠性,避免由于网站访问人数剧增而引起网站系统崩溃等情况的发生,从而减少不必要的损失。     

基于自适应遗传算法的LS—SVM漏磁缺陷重构

提出基于自适应遗传算法的最小二乘支持向量机算法（AGA-LS-SVM）的新方法，用于二维缺陷重构，建立由缺陷的漏磁信号到缺陷二维轮廓的映射关系。该方法实现人工裂纹缺陷的二维轮廓的重构，试验结果表明，该方法具有速度快、精度高和很好的泛化能力，为漏磁检测定量化提供了一种可行的方法。     

软件分域测试可靠性评估的注记

软件可靠性评估是软件可靠性研究的重要问题.文中通过反例证明了分域测试的Thayer Lipow Nel son评估方法是不正确的,将样本点排序法用于分域产生可靠性评估,获得了软件可靠性置信下限.最后给出一个实例说明该方法的可行性.     

定时截尾与序贯截尾可靠性试验方案分析比较

在生产方、使用方风险及MTBF值同等条件下,对定时截尾与序贯截尾2种试验方案的优缺点、基本原理和方法等进行了对比分析。定时截尾试验能够在事先确定最大累计工作时间及所消耗资源,但所需时间较长,试验成本较高,可应用于武器装备可靠性鉴定和验收试验;序贯截尾试验事先对试验总时间及试验所需用资源无法确定,只能根据事先拟定的接收、拒收条件结束试验,无法估计MTBF的真值,但是所需试验时间较短,费用相对较低,可用于武器装备可靠性验收试验,也可广泛运用于医学及其它科学试验领域。提出了选择可靠性试验方案的基本原则,为科学选择试验方案提供了依据。     

利用状态机检测JAVA空指针引用故障

介绍了一种在控制流的基础上利用故障状态机对JAVA空指针故障进行检测的方法。该方法利用变量区间来表示状态的前提条件,对程序中不可达路径进行处理,从而达到减少误报的目的。     

Stage life testing

In progressive censoring, items are removed at certain times during the life test. Commonly, it is assumed that the removed items are used for further testing. In order to take into account information about these additional testing in inferential procedures, we propose a two‐step model of stage life testing with one fixed stage‐change time which incorporates information about both the removed items (further tested under different conditions) and those remaining in the current life test. We show that some marginal distributions in our model correspond either to progressive censoring with a fixed censoring time or to a simple‐step stress model. Furthermore, assuming a cumulative exposure model, we establish exact inferential results for the distribution parameters when the lifetimes are exponentially distributed. An extension to Weibull distributed lifetimes is also discussed.     

基于硬体拖靶的拖曳式干扰系统构建

战场复杂电磁环境对防空导弹提出了抗拖曳式干扰的新要求，在组织进行实际对抗效果飞行检验时，存在导弹威胁拖曳式诱饵载机安全的风险，影响试验的组织和决策。介绍了拖曳式干扰的系统组成、工作原理和实际使用问题，提出了基于现有硬体拖靶系统构建拖曳式干扰系统的方法，分析了拖曳式诱饵对拖靶系统飞行性能的影响。该构建方法可以有效解决困扰试验的安全问题，为后续系统的建设和试验提供参考。     

薄壳变速箱壳体动态响应仿真分析与试验验证

在ADAMS（Automatic Dynamic Analysis of Mechanical Systems）中搭建薄壳箱体的刚柔耦合虚拟仿真模型，进行动态响应仿真分析。在相同试验条件下，搭建薄壳箱体动态响应试验台架，并进行动态振动试验。利用Q-400非接触式测试系统测量台架试验结果。对比仿真分析和试验测量结果，验证了仿真分析模型的准确性和计算结果的可靠性。     

某型车载导弹发射制导装置现场快速检测方法

某型装甲车载反坦克导弹系统的发射制导装置，集光、机、电多种技术于一体，技术状态易受装载、运输等因素的影响。在导弹射击前，一般应在现场对发射制导装置进行快速检测以确定其技术状态。为了解决现场快速检测问题，分析了该型导弹系统发射制导装置的结构和技术特点，确定了现场快速检测的内容：用点光源的电视图像检测两个光轴不平度；用电压比较法检测点火电压和点火程序正确性；用指令频率变化检测控制指令正确性。开发了适于现场快速检测的装置，为部队射击保障提供了一种决策支持方法。