测量标准因素判定■控制图异常导致标准核查不通过的分析

依据GB/T 27025-2008《检测和校准实验室能力的通用要求》,计量技术机构应开展测量标准核查,休哈特控制图是标准核查工作的主要方法。本文简要介绍了基于休哈特控制图理论的标准核查方法,对测量标准因素引起的三种控制图异常进行了深入讨论,对异常原因进行了追溯,分析了测量标准可能存在的问题,并给出了排除失控因素的建议。     

平均值-极差控制图在地面放射性测量模型标准装置核查中的应用

地面放射性测量模型标准装置在国内属于最高计量标准,无法直接溯源。为确认其系列标准量值处于受控状态,本文采用了定期核查的方法,对核查测量结果通过制作平均值-极差控制图来反映标准量值复现的重复性和稳定性,进而确认标准量值的受控状态。     

浅析测量标准与核查标准

计量确认过程和测量控制过程是企业在按照GB/T19022-2003（idtISO10012：2003）《测量管理体系测量过程和测量设备的要求》标准建立和运作测量管理体系时无法绕过的两大主过程。在这两大主过程中最常见的莫过于测量标准和核查标准。要有效运作测量管理体系,我们必须弄清楚测量标准和核查标准如何使用和如何管理等问题。     

控制图在期间核查中的应用

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。     

控制图法对测量设备进行期间核查的应用

测量设备在两次检定／校准期间,一般通过期间核查来控制其计量性能的准确可靠,常规控制图法是最科学、可信度更高的期间核查方法。本文通过对万能工具显微镜期间核查实例,来论述用常规控制图的方法。     

利用控制图技术实现测量标准的质量控制

针对测量标准性能在两次送检之间的核查问题,通过控制图原理的分析,以实例的形式详细介绍了控制图技术在实现测量标准质量控制方面的应用,利用经常性的核查测试获取的数据进行统计分析,使用控制图技术实现对测量标准状态的监控,从而实现测量标准的连续质量控制。并从核查标准的选择、初始过程参数的建立、过程参数的调整、失控后的处置等4个方面分析了实际操作中需要注意的问题,为计量人员开展测量标准的核查提供参考。     

期间核查中"休哈特Shewhart控制图"的应用

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.     

基于EXCEL的标准核查控制图法的实现

标准核查是计量技术机构确保标准设备稳定、测量结果可靠的重要手段。控制图法是标准核查的主要方法,但人工绘制控制图计算繁琐,易出现差错。文章介绍了利用EXCEL软件对标准核查控制图进行数据分析处理及图表绘制的方法,利用该软件能有效提升数据处理的准确度,提高标准核查工作效率,实现了标准核查控制图自动数据处理与图线绘制。     

利用控制图做好测量仪器的期间核查

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。     

A Multivariate T2 Control Chart for Skewed Populations Using Weighted Standard Deviations

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.     

An Improved R (Range) Control Chart for Monitoring the Process Variance

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 R_i statistics. Copyright © 2004 John Wiley & Sons, Ltd.     

二厘米微波衰减标准装置不确定度的验证

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。     

基于声速核查方法的天然气能量计量标准装置

为解决天然气能量测量中组分数据测量频率低带来的测量周期内发热量变化无法核查的问题,利用声速核查天然气组分变化导致发热量、压缩因子的变化,研究了声速核查能量模型,搭建了具备10 MPa、2 000 m³/h测量能力的天然气能量计量标准装置,该装置测量能量的时间由原有的分钟级提升到秒级。通过天然气实流测量,对天然气能量计量标准装置的不确定度进行系统评定,其相对扩展不确定度为0.33%(k=2)。     

On the Performance of Shewhart median Chart in the Presence of Measurement Errors

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.     

无线电领域测量标准的过程控制

现行文件规定的过程控制方法对于部分无线电领域的测量标准过于严格,导致无法利用核查数据建立测量标准的过程控制图,本文提出一种适用于无线电领域的控制图设计方法,为标准使用维护人员提供一种参考。     

A Reevaluation of the Adaptive Exponentially Weighted Moving Average Control Chart When Parameters are Estimated

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.     

紫外-可见分光光度计国家标准和检定规程的比较和分析

通过对紫外-可见分光光度计国家标准和检定规程中,对各项技术指标的比较,指出两者在波长重复性、杂散光、基线平直度、噪声和漂移等性能要求存在的差异,直接影响该仪器在生产、使用和监管环节的有序进行,对该仪器各项技术指标性能的一致性评价提出要求。