产品可靠性的Bootstrap区间估计方法

将Bootstrap估计方法引入到可靠性统计分析,提出了可靠性参数和特征量的Bootstrap区间估计方法;同时,通过对Bootstrap估计值进行纠偏处理,解决了小样本条件下Bootstrap区间估计的精度问题,并由此求得了某型航天电连接器可靠性模型参数的置信区间估计值。统计模拟的结果表明,经中位值纠偏求得的可靠性的置信区间,其估计精度能基本满足置信度的要求。     

Pareto产品可靠性试验最少试件数的确定

利用数理统计方法对Pareto产品最少试件数的确定进行综合分析。建立试验数据服从Pareto分布的可靠试验模型。基于极大似然估计,采用Bootstrap法构造分布参数的置信区间,给出以可靠性评估为中心的Pareto产品最少试件数的确定方法。最后,应用计算机模拟方法验证所提理论的正确性和可行性。     

基于Bootstrap方法的可靠性评估

针对机械系统可靠性试验数据分析中小子样疲劳性能数据难以满足经典统计方法容量要求的问题,将Bootstrap方法引入到小子样下母体百分位置信下限的计算。提出一种半参数Bootstrap方法用于计算正态分布变量的可靠度置信下限,并以某数控装备伺服驱动系统的可靠性分析实例验证该方法的可行性。     

二元Wiener过程下的小样本电主轴可靠性分析

针对高速电主轴产品的退化过程具有多个退化特征量,以及退化过程平稳、缓慢的特点,采用二元Wiener过程对其进行可靠性建模,并将二元Wiener过程的漂移参数看作随机变量来体现电主轴的个体差异性。利用极大似然法结合虚拟增广样本法和Bootstrap法来估计模型中的未知参数,以解决被试电主轴的小样本问题,得到电主轴产品寿命的可靠度函数。最后,通过对2根磨削电主轴产品的退化数据进行比较分析,验证了所提方法的合理性与精确性。     

基于回归与Bootstrap方法的仿真模型确认

为了实现有限数据段动态实验数据的系统仿真模型的确认,本文给出了基于回归分析与Bootstrap方法的仿真模型确认方法,该方法首先根据真实系统实验输出数据建立系统回归模型,然后用Bootstrap方法对回归模型参数的分布特征进行分析并确定置信区间,最后考察仿真模型输出数据二次建模回归参数与置信区间的一致性,从而实现了有限数据段动态系统实验统计确认.文中通过实例说明了该方法的应用,从而证明了该方法的有效性.该方法可应用于一些武器系统性能仿真模型的确认.     

基于计算机视觉的电测仪表自动识别方法的研究

研究图像处理技术在仪表自动化校验中的应用方案,详细介绍了基于最大似然估计的最小二乘拟合方法来确定指针和刻度线的参数.利用计算机视觉识别技术、信息处理技术和智能仪器设计原理,可从根本上解决电测仪表快速、准确的自动校验问题.     

确定截尾试验数据统计分布模型的方法

研究有替换定时与定数、无替换定时与定数共4种截尾可靠性试验数据统计分布模型的确定方法.首先把试验数据区分为失效与非失效数据两部分, 然后建立包含这两部分数据可能的假设分布的似然函数; 根据极大似然原理与微分极值原理,发展比较似然函数值、预测与生产实际情况的一致性和尾部预测的安全性确定较好统计模型的方法.实例说明方法的可用性.     

整体推断的极大似然方法

提出整体分布参数的概念，给出分布参数与整体分布参数、状态变量之间的一般关系式，建立任意分布整体推断的极大似然方法，推导出整体推断的点估计和置信限、置信区间的估计公式。该方法可以将不同状态下的试验数据作为一个整体进行统计推断，全面开发利用不同状态下试验数据之间相互提供的横向信息，从而使可使用的信息量远远大于只能分别在各自状态下对试验数据进行统计分析的传统极大似然方法。本文方法仅要求所有状态下的试样总和是大样本，呼个状态下的试样数量则可以是小样本，而传统的极大似然方法要求每种状态下的试样数量都必须是大样本。因此，整体推断的极大似然与传统的极大似然方法相比，在精度相同的情况下可以节省大量试样；而在试样数一定的条件下，又能提高预测精度。     

基于LabVIEW回归分析函数库的构建

使用图形化开发环境LabVIEW能够高效快捷地开发虚拟仪器软件系统,但用其进行多元数据的相关性分析时却存在一定不足,本文提出了一种在LabVIEW环境下,根据回归分析中的最小二乘原理.建立任意函数回归分析模型的方法.     

随机数组统计偏差对Weibull分布参数估计的影响

通过计算28组在(0,1)准均匀分布的随机数组的统计量偏差,并重新计算其随机寿命的Weibull参数,发现形状参数κ或尺寸参数λ的分布是随机数组统计量偏离期望值造成的,并且可以近似表达为4个统计量偏离值的一次线性方程。与此类似,从4组实测疲劳寿命数据也可以得知它们的随机数组统计量,从而估计拟合Weibull参数的偏差。     

An integration method for reliability analyses and product configuration

Reliability has been regarded as an evaluation criterion in production configuration, the key step in mass customization. In this article, the authors focus on the integration of reliability analysis and configuration at the component level. Possible failure causes obtained with a fault tree analysis (FTA) are mapped to the product configuration network model via a functional model and a limitation matrix. Next, when a configuration scheme is generated through intersection of a connection matrix and a generation matrix, its reliability can be achieved with the integrated FTA so to compare with those of other schemes in optimization. Such an integration method is also adaptable for situations where the original fault tree is changed, and several fault trees are involved together. Finally, an example of configuring a laptop computer is used to illustrate the whole integration process.     

机械可靠性设计中设计变量的统计分析方法

针对机械可靠性设计中设计变量的特点,研究了设计变量的统计分析方法,给出了不同情况下设计变量的统计特征值求法,供进一步设计使用。     

Bootstrap methods for statistical inference from stereological estimates of volume fraction

We suggest the use of bootstrap methods for inference from stereological estimates of volume fraction. An informal introduction to stereological estimation of volume fraction and to principles of bootstrap techniques is given. The bootstrap method is a robust computer-intensive resampling technique, based on independent random sampling from a data set with replacement. Bootstrap methods were used to estimate confidence intervals for volume fractions, and to test for a significant difference between estimated volume fractions from two samples. Two sampling designs are considered: independent replicated samples (visual fields) from a single object, and estimates of volume fraction from multiple independent objects. The methods are presented as worked examples on real data sets obtained from tumour pathology (mammary cancer, pancreatic cancer). The volume fraction of glandular lumina per total volume of the epithelial phase was chosen as target parameter. It indicates the degree of glandular differentiation in adenocarcinomas and is estimated as a ratio-of-means statistic with variable denominator within cases. The confidence intervals of the volume fraction estimated by the bootstrap method were slightly narrower than the parametrically calculated confidence intervals for all data sets. The outcomes of significance tests based on the bootstrap technique were unchanged as compared with classical tests based on the assumptions of normality and homoscedasticity of the data. Special attention was paid to the reproducibility of the bootstrap technique in replicated trials on the same data.     

Modeling of plasma spray coating process using statistical regression analysis

This study aimed to correlate outputs of a plasma spray coating process with its input parameters. Central composite design of experiments had been followed to conduct the experiments on plasma spray coating process, in order to collect its input–output data. The effects of four input parameters, namely primary gas flow rate, stand-off distance, powder flow rate, and arc current on three outputs (responses), such as thickness, porosity, and microhardness of the coatings, had been studied using non-linear statistical regression analysis. Such an analysis yielded the response equations, and viability of these equations had been tested on a set of experimentally obtained cases. The above four process parameters were found to have varying influences on different responses. However, all the above three responses were found to be significantly dependent on primary gas flow rate.     

统计公差分析的卷积算法

统计公差方法在保证产品质量的同时降低生产成本.卷积算法是计算统计公差分布的精确算法.采用卷积算法对均匀分布的随机变量进行求和,与Monte-Carlo法和矩法相比,该方法具有较快的速度和较高的精度.     

箱形梁焊接结构安全可靠性分析方法

根据概率损伤容限分析及可靠性理论，提出了一种基于箱形梁的焊接结构安全可靠性分析方法，给出了该类结构疲劳裂纹随机扩展过程中较普适的α—αc干涉模型和结构疲劳可靠性表达式。在给定与疲劳寿命有关的各参数条件下求得动态可靠性曲线，从而在箱形梁类的焊接结构设计中，可以很方便地根据可靠性要求，确定或选择设计参数，并在设备使用过程中按周期进行检查和维修。     

A statistical method for evaluating structural reliability and minimum structural creep life at elevated temperature

A study of the observed scatter of time for creep rupture of a given structural material, operating under identical conditions of stress and temperature, is given, using probabilistic concepts. Reliability functions for creep rupture time and also for the corresponding minimum creep rupture time for structural materials, under known conditions of temperatures and stresses are given, in terms of the empirical physical and chemical parameters of the materials. The reliability function is the probability of successful operation of the material, under the given operating conditions. Tables and graphs are prepared which enable easy applications of the results to be made on simple practical problems.     

空间机构位置分析的矢量回归法

本语文给出了一适中矢量回归公式,用来解决空间机构位置分析问题。该方法不需要引入坐标系,计算量小,具有通用性,易于写电算程序,是一种易于掌握的简便方法。     

A double weighted stochastic response surface method for reliability analysis

The weighted stochastic response surface method (WSRSM) has been demonstrated to be effective in improving the accuracy of the estimation of statistical moments and probability of failure (PoF) upon the stochastic response surface method (SRSM). However, it has been noticed that the weighting method in WSRSM may have little and sometimes negative impact on PoF estimation especially in the cases of low PoF. To mitigate this issue, a new double weighted SRSM (DWSRSM) is proposed that the weights of sample points are determined based on their importance not only to regression but also to PoF estimation. Specifically, relatively larger weights are assigned to points closer to the failure surface, which significantly accounts for the accuracy of PoF estimation. Comparative studies show that DWSRSM outperforms WSRSM producing more accurate PoF estimation without incurring additional function evaluations. An application of DWSRSM to the rocket design further demonstrates its effectiveness for PoF estimation.     

机械可靠性分析与设计的一种显式迭代算法

基于改进的一一次二阶知釜对机械可靠性分析和单一设计变量的机械可靠性设计问题,本文提出了计算结构可靠度和确定结构可靠性参数的一种显式迭代算法。与有关文献相比较,这种方法优点是无需解域变换、无需人工计算功能函数的偏导数和无需解结构失效的极限状态方程具有较为简便的计算形式和较高的计算效率,可方便地算出结构的可靠度和结构可靠性参数。本文方法具有一阶计算精度。