Bayesian Analysis of Pareto Reliability With Dependent Masked Data

In this paper, we consider a series system with two $s$-independent components, each of which has a Pareto distributed lifetime. We assume the lifetime data from the system are masked, and the masking probability is dependent. Noninformative prior, and conjugate prior are considered; and Gibbs sampling method is used to obtain the estimators of the unknown parameters, the reliability function, and the hazard function. A numeric example demonstrates how to apply the theoretical results.      

采用复高斯分布模型的两步噪声幅度谱估计算法

噪声幅度谱估计是有效抑制外界噪声干扰、提高语音增强算法整体输出性能的重要环节。但目前针对该问题的研究相对较少,常用的语音激活检测算法只能在语音不存在阶段对噪声信号的幅度谱进行更新或估计,无法适用于更为复杂的非平稳噪声环境。为克服这一问题,本文基于噪声频谱的复高斯分布模型假设,提出了新型的两步噪声幅度谱估计算法。算法首先采用软判决技术计算噪声信号的功率谱,然后再结合复高斯分布条件下信号幅度谱和功率谱之间的数学关系间接地获取噪声幅度谱的估计。文中基于这一结论给出了两种估计算法,并在多种噪声环境下对它们的性能进行了仿真评估,其测试结果有效表明了提出算法优良的估计性能。      

Performance and Measures of Performance for Estimators of Brain Potentials Using Real Data

A number of filtering and smoothing procedures have been proposed for estimating evoked brain potentials. Their common goal is to reduce noise further than averaging. A statistical method is proposed for comparing these estimators for real data, thereby avoiding the use of simulated data, which usually are not representative of the shapes encountered for signal and noise and might also rely on some artificial assumptions. This approach is applied to visual evoked potential (both flash and pattern reversal). Filtering methods offer substantial gains in mean square error, but most of the gain is obtained trivially by attenuating the average. This points out the need for also using other loss functions. In terms of these, adaptive filtering brings at best gains equivalent to smoothing.     

Estimators for Parameters of a Series System Under an Attribute Life Test Situation

Estimators for failure-law parameters are derived for the components of a series system under an attribute life test situation where the parameters of the failure laws are unequal. Exponential, Rayleigh, mixed exponential and Rayleigh, and a special case of the Weibull failure models are treated. An example uses simulated data for a 10-component system.     

Empirical Bayes Estimators of Reliability for Lognormal Failure Model

Empirical Bayes (EB) procedures are considered for estimating the reliability R(t;?,?) = gaufc[(ln t -?)/?] for the lognormal failure model. EB estimators are obtained for the 2 cases: i)? is unknown and ? is known, and both ? and ? are unknown. The empirical Cdf of the maximum likelihood estimators of the parameters is used to obtain the EB estimators. ii) A smooth EB estimator of R(t;?,?) is developed when ? is unknown and ? is known. A modification of this estimator is proposed for both ? and ? unknown. In both cases, EB estimators are obtained for complete samples at each testing stage. Monte Carlo simulations are presented to compare the EB estimators and the maximum likelihood (ML) estimators of R(t;?,?). The simulations indicate that the smooth EB estimators have smaller mean squared errors than the other EB estimators or the ML estimators.     

Estimators Using Noisy Channel Samples for Fading Distribution Parameters

The problem of estimating parameters of two main fading distributions, Ricean and Nakagami-$m$, is considered. Unlike most previous estimators which are designed to use samples from a noiseless channel, new estimators which use noise-corrupted samples are proposed. Both maximum-likelihood designs and moment-based designs are considered. The performances of the new estimators are examined and compared with those of previous estimators derived in the literature. Numerical results show the superiority of the new estimators for operation in noisy channels.     

A Reliability Model for Dependent Failures in Parallel Redundant Systems

The concept of Equivalent time is introduced to find the hazard rates of elements in a parallel redundant systems which is subject to dependent failures. True acceleration is defined as an adjunct to this concept.     

Likelihood Inference for Life Test Data

This paper reviews the basic ideas of likelihood inference and applies them to some reliability and life testing problems connected with the exponential distribution. Various censoring schemes are considered and the likelihood approach is shown to provide a unified framework for treating exact solutions to estimation, prediction, and population-comparison problems. These solutions are provided in a well defined but non-probabilistic form. The classical s-confidence procedures depend strongly on imaginary exact repetitions of the form of the experiment being analyzed. This is often unrealistic and impractical. The data on hand can be directly analyzed by examining the likelihood function.     

Probability Limits for Life Test Data

In this paper a general theory for constructing probability limits for life test data is briefly discussed. It is then applied to a set of life test data to determine which of three specified Weibull distributions give the best fit.     

威布尔分布无故障数据的可靠性评估

对于威布尔分布无故障数据可靠性评估方法中形状参数已知和未知的两种方法,通过一个例子进行对比分析,指出当形状参数毫无所知时,所得到的基本可靠度置信下限估计最为保守。通过相似产品的信息和工程经验对形状参数作出一个较为精确的估计是可行的。     

数据中心供配电系统可靠性的研究

数据中心供配电系统可靠性非常重要,文章研究了数据中心供配电系统可靠性的评价方式,提出优化整改的建议措施,旨在为增强系统运行可靠性、维护数据中心的稳定性提供帮助。     

A Monte Carlo Technique for Obtaining System Reliability Confidence Limits from Component Test Data

A digital computer technique is developed, using a Monte Carlo simulation based on common probability models, with which component test data may be translated into approximate system reliability limits at any confidence level. The probability distributions from which the component failures are assumed to come are the exponential, Weibull (shape parameter K known), gamma (shape parameter ? known), normal, and lognormal. The components can be arranged in any system configuration, series, parallel, or both. Since reliability prediction is meaningful only when expressed with an associated confidence leve, this method provides a valuable and economical tool for the reliability analyst.     

LED可靠性评估的加速寿命试验设计方法

介绍了一种关于发光二极管（LED）可靠性评估的加速寿命试验设计方法。通过这个方法,在针对LED的性能退化现象和运行不稳定问题进行加速试验设计时,可以在已知目标可靠度和置信度的前提下,定量地确定满足可靠性要求的试验用样本量、加速应力水平以及试验时间。同时,用于发光二极管加速寿命试验的基本设计思想,可以广泛地应用于常见电子元器件的器件产品质量认证或可靠性评估等试验设计中。     

基于区域约束的机场场面目标跟踪

现有的可靠性鉴定试验方案在一定的风险约束下需要较大的试验工作量,而大型复杂装备受经费、试验条件等因素的限制难以进行大量的试验。针对这一问题,以整机故障率为验证指标,提出利用分系统试验数据制定整机可靠性鉴定试验方案的新方法。该方法首先利用分系统试验数据计算整机故障率置信上限,然后利用两点分位数方法确定整机故障率的先验分布参数,最后依据贝叶斯最大后验风险准则制定了新的可靠性鉴定试验方案。实例对比分析表明,与传统试验方案相比,新方案将明显节约试验时间,减少试验工作量。     

从一起触电事故谈配电系统的安全措施

针对一起10 kV配电变压器高压侧避雷器爆炸引起的低压侧用户电击死亡事件,分析了触电事故的原因,提出了保证配电系统和人身安全的有效措施。     

通信产品系统可靠性预计和分配

本文主要介绍系统可靠性建模、可靠性分配和预计的一种思路，便于在今后的产品设计过程中加强可靠性系统设计。     

IC长贮存寿命评价方法

高可靠长寿命产品在军事、航空航天、电子工业、通信等领域应用越来越广泛,如何保障其可靠性与预测其寿命是值得深入研究的重要问题。越来越多的单位,特别是航空航天系统的单位,对其选用的产品提出了具有32年贮存寿命要求的高可靠性指标。长寿命及超长寿命的电子元器件的贮存寿命评价是以加速试验为评价方法的。建立准确的失效机理及模型是评价正确与否的关键。文章通过收集大量高温贮存及常温贮存的实测数据,建立失效模型,推算出应力条件及相应的加速因子。文中实践证明,通过模型仿真出的贮存寿命具有高的可信度。     

高温贮存寿命评估试验

元器件分别进行常温储存试验和高温贮存试验,通过常温储存试验累积试验数据并以此研究总结元器件长期储存性能参数变化规律和失效模式。通过高温贮存试验加速元器件常温储存过程累积试验数据,根据关键参数随加速试验的变化情况,得到高温贮存条件相对常温储存条件的加速因子,根据加速因子得到加速贮存试验的时间,在该高温点下进行相应时间的加速贮存试验。试验结果即为常温特定年限储存寿命的预计结果,从而在较短的时间内对元器件长期储存寿命做出评定。     

A Monte-Carlo Technique for Estimating Lower Confidence Limits on System Reliability Using Pass-Fail Data

Several methods for estimating lower s-confidence limits (LCLs) for system reliability were examined using pass-fail data on the components. A new technique was used to obtain limits for selected systems. These limits were compared to those obtained by other methods. The new method was tested to verify its accuracy. Results indicate that the proposed technique is simple to understand, easy to implement, and accurate. One need only supply the component reliabilities, the number of component tests, and the desired level of s-confidence, to obtain, not only an estimated LCL of the system reliability, but also an idea of the accuracy of the estimate. Most of the other techniques are not valid in the case of zero-failures, whereas this method easily accommodates such a situation. This method is not restricted to series systems; it can easily handle parallel configurations.     

应用高速数据采集卡实现WLAN测试系统

近年来已有不少公司推出高速数据采集卡（High Speed Data Acqui-sition Card）,并声称可以应用在军用雷达信号分析、超声信号分析、数字广播信号分析,或是喷墨式墨盒系统测试等各个方面.