On Conformity Testing and the Use of two Stage Procedures

Conformity testing is a systematic examination of the extent to which an entity conforms to specified requirements. Such testing is performed in industry as well as in regulatory agencies in a variety of fields. In this paper we discuss conformity testing under measurement or sampling uncertainty. Although the situation has many analogies to statistical testing of a hypothesis concerning the unknown value of the measurand there are no generally accepted rules for handling measurement uncertainty when testing for conformity. Usually the objective of a test for conformity is to provide assurance of conformity. We therefore suggest that an appropriate statistical test for conformity should be devised such that there is only a small probability of declaring conformity when in fact the entity does not conform. An operational way of formulating this principle is to require that whenever an entity has been declared to be conforming, it should not be possible to alter that declaration, even if the entity was investigated with better (more precise) measuring instruments, or measurement procedures. Some industries and agencies designate specification limits under consideration of the measurement uncertainty. This practice is not invariant under changes of measurement procedure. We therefore suggest that conformity testing should be based upon a comparison of a confidence interval for the value of the measurand with some limiting values that have been designated without regard to the measurement uncertainty. Such a procedure is in line with the recently established practice of reporting measurement uncertainty as “an interval of values that could reasonably be attributed to the measurand”. The price to be paid for a reliable assurance of conformity is a relatively large risk that the procedure will fail to establish conformity for entities that only marginally conform. We suggest a two‐stage procedure that may improve this situation and provide a better discriminatory ability. In an example we illustrate the determination of the power function of such a two‐stage procedure.     

关于我国汽车检测业现状及发展的思考

汽车检测业是伴随着汽车技术的发展而发展的,在汽车制造业日新月异发展的背景下,检测业也应时而生,逐步发展起来,可以说检测站经历了从无到有、从小到大的发展,并已成为道路运输业不可忽视的组成部分。现阶段,汽车检测业的经营存在一些弊端,本文从检测业实际出发,提出有利于车辆检测业发展的几点思考。     

陶瓷砖产品质量分析与对策探讨

针对当前市场上销售的陶瓷砖存在的主要质量问题,对江苏地区陶瓷砖进行了针对性的抽样检测,并对检测结果进行了分析,提出了解决问题的方法和建议,期望能给普通消费者对于陶瓷砖的购买与选用起到一定的帮助作用。     

材料试验检测技术在公路工程中的应用分析

试验检测技术作为当前对公路路面施工中工程质量保证当中的重要环节,对路面工程施工的质量有着重要的作用。本文以公路路面养护中的主要材料试验检测方法和指标作为基础,从材料试验检测的作用和实际应用对其进行阐述,并指出在养护中运用这些指标和方法的重要性。     

我国辐照食品检测技术与标准的发展

文章介绍了我国几种常用的辐照食品检测技术及应用情况,阐述了近年来我国辐照食品检测标准的现状,并对我国未来辐照食品检测技术和标准的研究及发展进行了探讨。     

Memoryless Reigns of the “Sons of Heaven”

Human lifetimes have increasing failure rates; as people age (beyond early childhood) they are more likely to die. Viewing the succession of Chinese Emperors as a statistical ensemble we show that, unlike lifetimes, their reigns ceased at a constant rate for over two millennia, unaffected by elapsed time. In fact reign lengths of the “Sons of Heaven”, as the Chinese Emperors were known, followed a memoryless exponential distribution with a 10-year half-life. Becoming emperor not only influenced the duration of remaining life, but length of rule was independent of age at ascent. We propose an explanation for the observed exponentiality using asymptotic results from the theory of stationary stochastic processes.     

合约变异在测试数据优化中的研究及应用

软件测试是保证Web服务质量的重要技术手段,测试数据生成是Web服务测试的重要内容,而生成的初始测试数据量大,数据冗余,为了减少初始测试数据数量,提高测试数据的有效性,本文在变异测试方法的基础上,使用合约变异方法对初始测试数据进行优化,据此可以生成一批达到一定变异充分度的有效测试数据,并通过实验验证了方法的有效性。     

声波透射法在混凝土灌注桩桩身完整性检测中的应用

对于大直径混凝土灌注桩的检测来说声波透射法是当前最可靠的方法之一,能够相当准确的判别桩的各类缺陷。本文介绍了声波透射法的基本原理,在检测过程中需要注意的各类问题。通过现场检测实例提出了桩身存在缺陷时声学参数的几种特征。     

浅析线性规划方法在半导体制造计划中的应用

半导体制造业中产品种类繁多,工序复杂,对设备的利用率要求较高,因而相对于其它制造也来说,生产计划的优化也较为复杂。本文讨论了目前半导体行业中常用的启发算法和基于线性规划的优化方法。     

高炮随动系统自动测试中正弦机发送频率的确定

在某型高炮随动系统测试中,正弦机的发送频率直接影响着输出信号的平滑度,从而会影响测试的精度。为了避免在正弦机运行过程中,计算耗用过多机时,在正弦机发送之前,先计算出每个位置信号、前馈信号的数值,存放于内存中。本文根据该正弦机信号的特点,分析了几种正弦机角位置信号发送频率方式的优缺点,确定了正弦机发送频率的方式。