共查询到19条相似文献,搜索用时 109 毫秒
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杜敏 《现代测量与实验室管理》2012,(1):46-48
介绍了统计技术在计量标准期间核查中的应用,详细阐述了如何应用统计技术的控制图对计量标准的测量过程进行持续及长期的统计控制,使计量标准处于统计控制状态,从而确保量值传递的准确可靠。 相似文献
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期间核查中"休哈特Shewhart控制图"的应用 总被引:1,自引:0,他引:1
期间核查是根据JJF1069-2003第7.5.3.3款以及GB/T15481-2000第5.6.3.3款的要求,对计量标准(包括标准物质)按规定的程序和日程进行的一种检查.我所在期间核查过程中,应用了“休哈特Shewhart控制图”的方法.实践证明,这一方法具有易操作、结果直观、便于对数据进行分析等特点. 相似文献
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期间核查对于检验检测机构保证工作质量具有现实意义,文章依据JJF 1033—2008《计量标准考核规范》,以对电子天平进行期间核查为实例,详细讲述如何进行期间核查、如何绘制控制图以及控制图的作用等。 相似文献
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This paper proposes a heuristic method of constructing multivariate T2 control charts for skewed populations based on ‘weighted standard deviations’, obtained by decomposing the standard deviation into upper and lower deviations according to the direction and degree of skewness. The proposed method adjusts the variance–covariance matrix of quality characteristics and modifies the ellipsoidal probability density function contour of the multivariate normal distribution to a shape similar to that of the skewed distribution. False alarm rates and out‐of‐control average run lengths of the proposed control chart are compared with those of the standard control chart for multivariate lognormal, Weibull and gamma distributions, and the results show that considerable improvement over the standard method can be achieved when the distribution is skewed. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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An R chart is often used to monitor shifts in the process variability. However, the range, , statistics from a sampling distribution are highly skewed. Hence, the classical R chart based on the control limits will not give an in‐control average run length of approximately 370, or equivalently a type I error, . In this paper, an approach is shown to obtain the control limits of an improved R chart based on a desired type I error from the density function of the Ri statistics. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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采用传递比较法对二厘米微波衰减标准装置不确定度进行了验证。测量标准装置的重复性以组内实验标准偏差sn(A)定量表征,测量标准装置的稳定性用组间实验标准偏差sm定量表征。 相似文献
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Kim Phuc Tran Philippe Castagliola Narayanaswamy Balakrishnan 《Quality and Reliability Engineering International》2017,33(5):1019-1029
In the literature, median control charts have been introduced under the assumption of no measurement error. However, measurement errors always exist in practice and may considerably affect the ability of control charts to detect out‐of‐control situations. In this paper, we investigate the performance of Shewhart median chart by using a linear covariate error model. Several figures and tables are presented and commented to show the statistical performance of Shewhart median control chart in the presence of measurement errors. We also investigate the positive effect of taking multiple measurements for each item in a subgroup on the performance of Shewhart median chart. An example illustrates the use of Shewhart median chart in the presence of measurement errors. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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A Reevaluation of the Adaptive Exponentially Weighted Moving Average Control Chart When Parameters are Estimated
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Aya A. Aly Nesma A. Saleh Mahmoud A. Mahmoud William H. Woodall 《Quality and Reliability Engineering International》2015,31(8):1611-1622
The performance of control charts can be adversely affected when based on parameter estimates instead of known in‐control parameters. Several studies have shown that a large number of phase I observations may be needed to achieve the desired in‐control statistical performance. However, practitioners use different phase I samples and thus different parameter estimates to construct their control limits. As a consequence, there would be in‐control average run length (ARL) variation between different practitioners. This kind of variation is important to consider when studying the performance of control charts with estimated parameters. Most of the previous literature has relied primarily on the expected value of the ARL (AARL) metric in studying the performance of control charts with estimated parameters. Some recent studies, however, considered the standard deviation of the ARL metric to study the performance of control charts. In this paper, the standard deviation of the ARL metric is used to study the in‐control and out‐of‐control performance of the adaptive exponentially weighted moving average (AEWMA) control chart. The performance of the AEWMA chart is then compared with that of the Shewhart and EWMA control charts. The simulation results show that the AEWMA chart might represent a good solution for practitioners to achieve a reasonable amount of ARL variation from the desired in‐control ARL performance. In addition, we apply a bootstrap‐based design approach that provides protection against frequent false alarms without deteriorating too much the out‐of‐control performance. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献