可靠度置信限曲线等同性原理及其参数估计

本文对可靠性连续分布的置信限曲线变化进行了研究，证明了可靠度分布函数置信度为γ的单侧置信上（下）限曲线，同时也是具有该分布函数的母体百分位值的置信度为γ的单侧置信下（上）限曲线，并且提出了一种利用秩分布确定可靠度置信限曲线数学表达式中参数的方法，由此可求出可靠度的置信限。     

基于最优置信限法机械密封的可靠性研究

为了对机械密封的寿命进行可靠性评定,文中在其寿命服从两参数威布尔分布时,基于无失效数据的最优置信限法给出了可靠性参数—可靠度、可靠寿命的置信限,并分析了影响其估计值的主要因素。     

混凝土疲劳损伤强度可靠度置信限分析

以三参数Weibull概型为基础,结合大量C15混凝土试件的试验和某混凝土重力坝的原型观测反演结果,建立了描述高应力水平区域的混凝土在较低损伤量下低周疲劳强度的置信限分析模型,得到了具有给定置信度的疲劳强度、疲劳寿命和疲劳损伤三者间的关系曲线,NSP---g和DSP---g曲线。利用本文方法可方便地在给定置信限内计算混凝土在给定应力水平条件下的疲劳寿命、损伤量和剩余强度, 对混凝土做考虑损伤的可靠度设计,以及对已建结构进行可靠度评价。     

基于无失效数据的指数型元件及系统的可靠性置信限

设指数寿命型元件有成败型试验数据,在ti时刻随机抽取Ni个元件试验,结果无失效元件,基于试验数据（ti,Ni,Ni)(i=(1,k)^-,讨论了元件及系统的可靠性置信限。     

软件测试数据的统计分析

软件可靠性评估是软件可靠性研究的重要问题,本文研究了软件测试数据的样本点序法,获得了软件可靠度的置信下限,证明了该置信限的最优性。最后给出一个实例说明该方法的可行性。     

指数型元件的贮存可靠性的置信限

基于元件的定期检测数据,不确定数据,通过把各检测时刻的元件的试验数据,折合成ｔ时刻下元件的伪试验数据来确定元件的贮存可靠性的置信限。给出的数字例并进行了模拟计算,证实新方法效果偏好,操作方便。     

指数型元件贮备系统可靠性的近似置信限

基于元件的定数截尾寿命试验数据,切换开关的成败型试验数据,给出了指数型元件贮备系统可靠性的近似置信下限的计算公式。     

测量不确定度分析方法在计量管理技术中的应用

测量不确定度是用来表征测量过程中各项误差的综合作用所引起的测量结果对其真值可能偏离的一个区间。相应于具有给定置信概率区间的置信限即为测量不确定度的表征值。对测量不确定度的处理,按传统的分析方法有实验统计法和分析计算法。近年来为了方便一般工程的应用,国际计量局提出按其数值的评定方法估     

毛细管气相色谱测定室内空气中苯系物分析误差预评价

目的:评价毛细管气相色谱测定室内空气中苯系物的分析误差。方法:对空白溶液、0.1c标准溶液、空气样品、加标空气样品,采用精密度和偏性质量控制程序进行质控试验。结果:4种试样的批内批间变异分析(F相似文献   

工业废水中挥发酚在不同保存条件对样品稳定性的影响

探索工业废水中挥发酚在不同保条件下对样品稳定性的影响。方法:采集炼焦厂废水4份,每份试样按每升水加入2m L硫酸,在另2份中加入0.04μg/m L的酚标准溶液,加标样和试样各1份分别在25℃常温和4℃冷藏条件下保存,酚的测定按水和废水监测分析方法(GB7485-87)中4-氨基氨替比林光度法。结果:酚浓度在0.002~0.06μg/m L范围内线性良好,相关系数r=0.9992,25℃常温保存酚的测定值为0.031±0.0072μg/m L,对试样的稳定性影响显著(t值为4.44t0.05(9)=2.26));4℃冷藏保存苯酚的测定值为0.036±0.0018μg/m L对试样的稳定性影响不显著(t值为1.89t0.05(9)=2.26)),准确度的置信限(R/d)为0.96。结论:工业废水中引起挥发酚试样不稳定因素主要来源于酚类性质的不稳定,试样保存温度、放置时间和光照射是影响结果准确性的主要因素。     

Generalized confidence intervals for process capability indices

The concept of generalized confidence intervals is used to derive lower confidence limits for some of the commonly used process capability indices. For the cases where approximate lower confidence limits are already available, numerical comparisons are made among the available approximations and the generalized lower confidence limit. The numerical results indicate that the generalized confidence interval does provide coverage probabilities very close to the nominal confidence level. Two examples are given to illustrate the results. Copyright © 2006 John Wiley & Sons, Ltd.     

Confidence limits for compliance testing using mixed acceptance criteria

For manufactured items sold by weight or volume, this article considers mixed acceptance criteria that put limits on the sample mean or on an upper confidence limit based on the sample mean and on the number of individual sample units that are nonconforming. For a normally distributed quality characteristic of interest, this article develops lower confidence limits for the mixed acceptance criteria applying the concept of a generalized pivotal quantity and applying a bias-corrected and accelerated parametric bootstrap. The accuracy of the confidence limits is assessed using estimated coverage probabilities, and the results are illustrated with an example.     

液体火箭发动机试验流量测量系统可靠性评定

针对液体发动机可靠性评定的研究现状,从性能可靠性和结构可靠性两个维度对流量测量系统的可靠性进行评定。给出了测量系统性能可靠性的定义,将测量数据视为正态分布,通过区间估计的方法计算单侧可靠性置信下限。给出了测量系统结构可靠性的定义。根据流量测量系统串联可靠性框图,对将指数寿命失效型试验信息转换为二项成败型试验信息。采用L-M法(Lindstrom-Maddens),结合查表和线性插值法求解结构可靠性置信下限。该测量系统可靠性评估方法对行业内测量技术人员具有重要的参考意义。     

Confidence Intervals for Process Capability Indices for the Unbalanced One‐Way Random Effect ANOVA Model

Confidence intervals for process capability index C_pk are developed for the unbalanced one‐way random effect model using Bissell's approximation method. The proposed limit is compared with the generalized lower confidence limit obtained using the generalized pivotal quantity method. To assess the accuracy of the method, a simulation study is presented. The results are illustrated with an industrial example. Copyright © 2011 John Wiley & Sons, Ltd.     

Construction of upper confidence limit of coefficient of variation for content uniformity

Relative standard deviation (coefficient of variation) plays an important role in meeting the current compendial requirements for content uniformity. Since the sample RSD value would vary from sample to sample in a population (batch), the scientist would need not only the sample estimate of the RSD but also its 95% two-sided upper confidence limit, for making the proper statistical inference as well as for arriving at the appropriate pharmaceutics decisions. The primary purpose of this paper is to depict the five available methods for determining the confidence limit and to discuss their relative merits and similarities in the context of a content uniformity study associated with Product-C. Suitable tables are furnished to facilitate rapid access to the desired RSD confidence limit.     

Measuring the Process Yield for Simple Linear Profiles with one‐Sided Specification

Profile monitoring is mainly for checking the stability of the relationship between response and explanatory variables over time based on observed data. Linear profiles are common in calibration applications. In this study, we develop two new indices for measuring the process yield for simple linear profiles with one‐sided specification. The asymptotic distribution of the estimated index is provided. The approximate lower confidence bound for the true process yield is also obtained and used to determine whether the process yield meets the quality requirement. A simulation study is conducted to assess the performance of the proposed method. The results show that the coverage rates of the confidence intervals for all simulated cases are greater than the 95% lower limit of the stated nominal value. One real example is used to illustrate the applicability of the proposed approach. Copyright © 2013 John Wiley & Sons, Ltd.     

Limit of detection determination for censored samples

The problem of setting the limit of detection is considered for censored samples and heterogeneous errors. After formal definitions of the critical level and of the method detection limit, we obtain simplified maximum likelihood-type estimators. The estimation problem of the truncation parameter and its uncertainty are reviewed. Upper confidence bounds for the limit of detection are derived and some simulation results are given.     

A New Method for Constructing Confidence Intervals for the Index Cpm

In the statistical literature on the study of the capability of processes through the use of indices, C_pm appears to have been one of the most widely used capability indices and its estimation has attracted much interest. In this article, a new method for constructing approximate confidence intervals or lower confidence limits for this index is suggested. The method is based on an approximation of the non‐central chi‐square distribution, which was proposed by Pearson. Its coverage appears to be more satisfactory compared with that achieved by any of the two most widely used methods that were proposed by Boyles, in situations where one is interested in assessing a lower confidence limit for C_pm. This is supported by the results of an extensive simulation study. Copyright © 2004 John Wiley & Sons, Ltd.     

Measuring the Process Yield for Circular Profiles

Two indices C_p(circular) and C_pk(circular) based on the functional method have been proposed to measure the process capability of circular profiles. However, these two indices only provide potential capability and a lower bound on the process yield, respectively. In this paper, we develop a new yield index S_pk(circular) for circular profiles. This index provides an exact measure of process yield. The asymptotic normal distribution of the estimated index is derived. The statistical inferences such as hypothesis testing, confidence interval, and lower confidence interval can be easily constructed. A simulation study is conducted to assess the performance of the proposed method. The simulation results confirm that the estimates are close to the true value and the coverage rates of the confidence intervals are greater than the 95% lower limit of the stated nominal in most cases. One real data set is used to illustrate the applicability of the proposed method. Copyright © 2013 John Wiley & Sons, Ltd.     

复合材料B基准值计算方法研究进展

在复合材料的结构设计中,复合材料的许用值是关键参数之一.通常采用B基准值这一统计量作为复合材料的许用值,B基准值是具有95％置信度的90％置信下限.准确计算复合材料的B基准值是复合材料安全、可靠应用的保障.本文归纳总结了复合材料B基准值计算方法的研究进展,详细分析了单点法、多环境样本合并法的计算原理、计算过程、适用条件...