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为克服不合格品数控制图(以下简称为np图)样本容量大、分辨率低的缺点,本文提出了一种新的控制图——三区分类控制图.文中介绍了其原理和使用方法,并就其样本容量与x控制图和np图进行了对比.最后还给出了一个应用示例. 相似文献
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本文研究了完全检验的质量控制问题,将广泛用于X-控制图的AT&T准则应用于完全检验,并根据完全检验的特点,提出一种新的最优模型,数值实验结果表明AT&T准则下的完全检验优于传统的完全检验. 相似文献
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本文研究了完全检验的质量控制问题,将广泛用于X-控制图的AT&T准则应用于完全检验,并根据完全检验的特点,提出一种新的最优模型,数值实验结果表明AT&T准则下的完全检验优于传统的完全检验。 相似文献
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刘桂真 《数学物理学报(A辑)》1994,(3)
设G是一个图,g和f是定义在图G的顶点集上的两个整数值函数且g<f.本文给出了过图的每条边有一个(g,f)-因子的新的简单的判断准则,并研究了它的应用。从而得到了一些关于图有(g,f)-因子的新的充分条件,推广了若干已有的结果. 相似文献
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控制过程方差的CUSUMQ图及其性质 总被引:1,自引:0,他引:1
崔恒建.控制过程方差的CUSUMQ图及其性质.数理统计与管理,1998,17(4),33~38.Qusenberry(1995)基于样本方差的标准化变换Φ-1[Hn-1((n-1)S2/σ20)]提出了控制过程方差的累积和(CUSUM)Q控制图。本文我们描述了在控制过程方差变化中这种CUSUMQ控制图的性质,并将控制图的设计方法用到单边及双边的CUSUMQ图,说明它几乎是最优的。而且我们发现在控制过程方差的微小变化时,设计的CUSUMQ图的性能要优于基于log(S2)的CUSUM和EWMA图 相似文献
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常规控制图应用的基本假设是从过程得到的测量值彼此独立,但许多连续型的制造业生产过程(例如化学和制药)往往存在自相关,此时常规控制图容易虚发警报。基于数据的样本自相关函数,本文改进了常规控制图的控制界限,使之适用于自相关过程,并运用常规X-s控制图和本文修正的X控制图对一个实际案例进行了比较分析,结果表明本文修正的X控制图可正确地判断过程是否处于受控状态。 相似文献
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关于动态质量控制图的设计理论 总被引:18,自引:0,他引:18
质量控制图是首先由Shewhart于1924年提出的,之后得到了广泛的研究与应用,取得了相当不错的经济效益与社会效益,尤其是对 后世界经济的发展做出了巨大的贡献。由于经典的质量控制图均假设抽样区间与样本容量是固定的,且控制限也是固定的(常用的即为3σ准则),这一点很不适合当今经济社会的发展。于是Reynolds et al(1988)提出了变化抽样区间的均值控制图,并由此形成了动态质量控制图这一新的研究领域。后来,又有人提出变化样本容量及变化控制限的控制图,并得到了一系列的关于这类动态控制图的研究成果。本文将对十几年来关于动态控制图的研究成果进行一些概述,并提出一些还有待研究的问题或方向。 相似文献
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「1」中研究了样本数较少时中位值和极差控制图。本文研究样本数较少时极值控制图的制定方法,给出与极值有关的统计量的分布,建立极值图的控制限,极值图不需计算,有关集中和分散的信息在一个图上给出,且可画上规格限,在实践中应用方便,本文制定的极值控制可应用于小批量生产的生产过程。 相似文献
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为了降低生产过程周期成本,本文对单位缺陷数服从几何分布时,可变抽样区间的指数加权移动平均(EWMA)控制图进行经济设计。首先建立可变抽样区间几何EWMA控制图的经济模型,使单位时间期望费用最小来确定参数的最优值;其次用遗传算法来寻找经济模型的最优解;最后对可变抽样区间几何EWMA控制图的经济模型进行灵敏度分析和最优性分析。研究结果表明单位时间期望费用分别随着异常原因发生的频率、过程失控时单位时间的质量费用、发现异常原因的时间期望值和纠正过程的时间期望值的增大而增大。 相似文献
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在制造过程中,对产品的不合格品数进行监控时,通常选用计数性控制图-np图,它是基于过程服从二项分布建立的,一般对于过程中出现的较大波动效果明显。为了提高控制图对不合格品数较小波动的监控效果,本文设计了产品不合格品数服从二项分布的EWMA控制图。提出可变抽样区间的二项EWMA控制图,并采用马可夫链法计算其平均报警时间。对固定抽样区间以及可变抽样区间二项EWMA控制图对比研究,表明当过程失控时,可变抽样区间二项EWMA控制图具有较小的失控平均报警时间,能够迅速监测出过程中的异常波动,明显优于固定抽样区间的二项EWMA控制图。 相似文献
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This paper considers the problem of finding limits for a statistical process control (SPC) chart for the process mean, when the process distribution is unknown. The bootstrap method estimates these limits relying on Monte Carlo methods, which are subject to simulation errors. Therefore this paper develops a computationally efficient enumeration method for exact calculations of the control limits. 相似文献
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This paper presents the formulations of the expected long-run cost per time unit for a system monitored by a static control chart and by an adaptive control chart respectively. The static chart has a fixed sampling interval and a fixed sample size. The adaptive chart has a fixed sample size but variable sampling intervals. The system is supposed to have three states, normal working state, failure delay time state, and failed state. Two levels of repair are used to maintain the system. A minor repair is used to restore the system if a detectable defect is confirmed by an inspection. A major repair will be performed if the system fails. The expected cost per time unit for maintaining such a system is obtained. The objective of such analysis is to find an optimal sampling policy for the inspection process. An artificially generated data example and a real data example are used to compare the expected cost per time unit for both the static and adaptive control charts. 相似文献
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In this paper, we design an attribute np control chart using multiple deferred state (MDS) sampling under Weibull distribution based on time truncated life test. This chart is constructed for monitoring the variation of mean life of the product in a manufacturing process. The optimal parameters of MDS sampling and the control limit coefficients are determined so that the in‐control average run length (ARL) is as close as to the target ARL. The optimal parameters of MDS sampling are sample size and number of successive subgroups required for declaring the current state of process. Out‐of‐control ARL is considered as a measure of the performance of proposed chart and reported with determined optimal parameters for various shift constants. The out‐of‐control ARL of the proposed chart obtained under various distributions is compared with each other. The performance of proposed control chart is compared with the performance of the existing control chart designed under single sampling. In addition, the economic design of proposed chart using variable sampling interval scheme is discussed, and sensitivity analysis on expected costs is also investigated. 相似文献
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Most industrial products and processes are characterized by several, typically correlated measurable variables, which jointly describe the product or process quality. Various control charts such as Hotelling’s T2, EWMA and CUSUM charts have been developed for multivariate quality control, where the values of the chart parameters, namely the sample size, sampling interval and the control limits are determined to satisfy given economic and/or statistical requirements. It is well known that this traditional non-Bayesian approach to a control chart design is not optimal, but very few results regarding the form of the optimal Bayesian control policy have appeared in the literature, all limited to a univariate chart design. In this paper, we consider a multivariate Bayesian process mean control problem for a finite production run under the assumption that the observations are values of independent, normally distributed vectors of random variables. The problem is formulated in the POMDP (partially observable Markov decision process) framework and the objective is to determine a control policy minimizing the total expected cost. It is proved that under standard operating and cost assumptions the control limit policy is optimal. Cost comparisons with the benchmark chi-squared chart and the MEWMA chart show that the Bayesian chart is highly cost effective, the savings are larger for smaller values of the critical Mahalanobis distance between the in-control and out-of-control process mean. 相似文献
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为了提高过程监控效率的同时降低过程控制成本,研究可变抽样区间(VSI)指数加权移动平均(EWMA)控制图的经济设计问题。首先建立基于预防维修和质量损失函数的VSI EWMA控制图联合经济模型;使单位时间的损失成本函数最小来确定参数的最优值;其次用遗传算法来寻找联合经济模型的最优解,并给出一个算例。最后对VSI EWMA控制图联合经济模型进行灵敏度分析,得出控制图模型参数对设计参数的影响关系。 相似文献