On the Sampling Distribution of Swap-Rate

When we are to select students using the result of an entrance examination, it is common to select N⁰ students out of N applicants on the basis of a composite score of m subtests, where N⁰, the number of students to be selected, is determined prior to the administration of the entrance examination. The swap-rate is an intuitively easy-tounderstand measure of the contribution of each subtest to the selection. The swap rate of the j-th test is defined as the proportion, to No, of the number of students who failed to pass the examination if the j-th test is not used for the selection.

In this paper we first discuss the sampling distribution of the swap-rate under the normality assumption and then show the result of a bootstrapping using real selection data.

     

Tables for Normal Sampling with Unknown Variance-the Student Distribution and Economically Optimal Sampling Plans

Industrial scientists and engineers often use experimental designs in which all degrees of freedom are used to estimate effects and consequently no classical estimate of the error is possible. Robust scale estimates provide an alternative measure of the error. In this study, several such scale estimators are evaluated based on the power or related significance tests. The pseudo standard error method of Lenth provides the best overall performance. Lenth's t approximation for critical values was found to be inaccurate, however, so new tables are provided. Additional recommendations are made according to the experimenter's prior belief in the number of likely important factors.     

火灾标准火烟雾颗粒测量及粒径尺度分布函数研究

烟雾是火灾探测的重要参量，烟雾颗粒粒径及其尺度分布直接影响到感烟探测器的灵敏度，而目前有关烟雾颗粒粒径的研究相当匮乏。采用扫描迁移率粒子测量仪对火灾标准火烟雾颗粒的粒径大小及其分布进行实验测量，并采用数学拟合方法系统研究了烟雾颗粒粒径分布函数，研究结果表明对数正态分布函数较好地描述了烟雾颗粒尺度分布特征，其结论有益于火灾探测基础研究的发展。     

Selection of Work Sampling Observation Times: Part I—Stratified Sampling

Various methods of selecting observation times in work sampling studies are presented, including simple random, systematic, and stratified sampling, and a new method called restricted random sampling. The attributes of these sampling methods are evaluated, particularly statistical efficiency, and the important advantages of stratification are demonstrated. Finally, the analysis of variance is recommended for statistical analysis of work sampling data to account for the presence of several sources of variation, in addition to sampling error.     

Estimation of the Standard Deviation of the Logistic Distribution by the Use of Selectkd Order Statistics

A technique is applied to ohtain unbiased eslimators with minimttm variance among the class of linear estimators for the standard deviation of of logistic. population with known mean. Coefficients for multiplying ordered observations are developed for complete and completc samples for n = 2(1)26. Each sample of size n is censored from above where m ≤ n. Then the smallest subset of l order slatistics from the set of m available order statistics is found which yields at list a 98.5% efficiency relative to the m-order-statistic estimator. The coefficients for the l-order-statistic estimator, the variance and efficiency relative to the estimatot, using all m order statistics are persented.     

Calculation of the Sampling Distribution of the Range

Two dynamic programming models are developed for a class of production-inspection problems. The two models correspond to two different levels of information and result in fixed-point and adaptive inspection policies respectively. Choice of the “optimal” model can then be made via comparison of expected benefits obtained versus the costs of deriving and implementing the solutions.     

On the Cumulative Distribution of Outgoing Quality: A New Criterion for Sampling Plans

A procedure is developed for designing rectifying sampling plans by attributes with a predetermined upper bound on the outgoing quality of the lots. These plans are derived so that the upper bound is satisfied with specified minimum probability regardless of the value of the process average. In addition, the average outgoing quality limit (AOQL) criterion is evaluated with respect to the probability bound concept. Computational procedures are presented that allow the design of sampling plans with user specified upper bounds with designated minimum probability 1 – α. A table is presented for determining sampling plans for the use of 1 – α = .95.     

Adaptive ―X Control Charts with Sampling at Fixed Times

The idea of a variable sampling interval with sampling at fixed times (VSIFT) has been presented by Reynolds. This paper extends this idea to the other two adaptive ―X charts: the variable sampling rate with sampling at fixed times (VSRFT) ―X chart and the variable parameters with sampling at fixed times (VPFT) ―X chart. The VSIFT, VSRFT and VPFT ―X charts are inclusively called the adaptive with sampling at fixed times (AFT) ―X charts in this paper. The control scheme and the design issue are described and discussed for each of the AFT ―X charts. A comparative study shows that the AFT ―X charts have almost the same detection ability as the traditional adaptive ―X charts. However, from the practical viewpoint, the AFT ―X charts are considered to be more convenient to administer than the traditional adaptive ―X charts. Overall, this paper advances the application of ‘sampling at fixed times’ to the adaptive ―X control charts. Copyright © 2004 John Wiley & Sons, Ltd.     

美军兵器装备包装标准体系分析及启示

简要介绍了美军兵器装备防护包装标准体系构成,并对其基本特点和存在的问题进行了分析。特别指出了美军包装工作的特点:20世纪70年代以来,美军理顺了装备研制与装备包装研制的关系,重视通用化、系列化、组合化建设,紧跟战争模式变化,改进装备的防护包装,确保新形势下的后勤保障,信息技术在防护包装上的应用发展迅速。建议我国兵器包装领域应提振信心,更新观念,在新军事变革中加速标准化进程,首先实现常规弹药的包装标准化建设。     

整体包装解决方案及其供应商的运行模式探讨

讨论了整体包装解决方案(CPS)的设计理念及其定义,在分析国内外数家有代表性的整体包装解决方案供应商(CPSS)的CPS内涵及其运行情况的基础上,总结并提出了较为实际可行的CPSS运行模式,包括其组织机构、工作内容和发展模式.     

Random Sampling Oscilloscope for the Observation of Mercury Switch Closure Transition Times

With the advent of new miniaturized mercury (Hg) switches with reputed transition times of the order of 10 ps, interest has been rekindled in their use in high-peed pulse measurements. Since there is no pretrigger signal available from a Hg switch, normal sequential sampling techniques are not useable to measure the fast Hg switch transition time. For this reason, a new random sampling time base unit was designed to perform these measurements at the low repetition rate of Hg switches. The time base may be used with commercial sampling oscilloscope systems through suitable interconnection terminals or possible interface equipment. It features three selectable time windows of 1 jus, 100 ns, and 10 ns. Using its time magnifier, the fastest sweep rate is 10 ps/cm. A variable trigger lead time control is provided. The trigger sensitivity is 5 mV.     

基于B/S模式的企业标准信息管理系统

本文介绍了标准信息化工作对提高企业核心竞争力的重要作用,提出了基于B/S模式的企业标准信息管理系统的架构方法,并结合所开发的系统实例着重讨论了MVC技术在B/S架构中的应用,介绍了实例系统各模块的主要功能和标准有效性确认模块的创新点,分析了各模块之间的内在联系,证明是一种较为先进和有效的设计模式。     

Multi-Censored Sampling in the Three Parameter Weibull Distribution

In life and fatique testing, multi-censored samples arise when at various stages of a test, some of the survivors are withdrawn from further observation. Sample specimens which remain after each stage of censoring continue to be observed until failure or until a subsequent stage of censoring. In this paper, maximum likelihood estimators and estimators which utilize the first order statistic are derived for the three parameter Weibull distribution. Estimators are also derived for the special case in which the shape parameter is known, a special case which includes the two parameter exponential distribution. An illustrative example is included.     

Variables Sampling Plans Based on the Normal Distribution

Sampling Plans are considered which call for the acceptance of a lot of material if both – ks ≥ L and + ks ≤ U, where L and U are the lower and upper specification limits and where and s are the sample mean and standard deviation and k is an appropriate constant. Some errors that need to be corrected in previous work are pointed out in interpretation of the mathematical formulas before plans of the type described can be properly applied. Tables are given for the constant k under two different circumstances. Table II applies when the sum of the proportions defective in the two tails of a normal distribution is to be controlled. Table III applies when each tail is to be controlled below preassigned values, i.e., so that one can say with probability y that the proportion in the lower tail (below L) of accepted lots does not exceed a preassigned value and simultaneously the proportion in the upper tail (above U) does not exceed its preassigned value. The same constants, in Table III, apply when all the defectiveness to be controlled is in one tail.     

关于超声体模的正确使用及维护

本文叙述了超声体模在日常使用中的维护与保养事项若干。     

On the Determination of Single Sampling Attribute Plans Based upon a Linear Cost Model and a Prior Distribution

The linear cost model previously formalized by Hald [4], [5], [9] is reviewed. Techniques are described which permit easy determination of sampling plans based on that model. The degenerate, the beta, and the two point distributions are considered as prior distributions of p, the process fraction defective. For calculations only standard tables and a desk calculator are required.     

Acceptance Sampling Plans with Truncated Life Tests for the Length-Biased Weighted Lomax Distribution

In this paper, we considered the Length-biased weighted Lomax distribution and constructed new acceptance sampling plans (ASPs) where the life test is assumed to be truncated at a pre-assigned time. For the new suggested ASPs, the tables of the minimum samples sizes needed to assert a specific mean life of the test units are obtained. In addition, the values of the corresponding operating characteristic function and the associated producer’s risks are calculated. Analyses of two real data sets are presented to investigate the applicability of the proposed acceptance sampling plans; one data set contains the first failure of 20 small electric carts, and the other data set contains the failure times of the air conditioning system of an airplane. Comparisons are made between the proposed acceptance sampling plans and some existing acceptance sampling plans considered in this study based on the minimum sample sizes. It is observed that the samples sizes based on the proposed acceptance sampling plans are less than their competitors considered in this study. The suggested acceptance sampling plans are recommended for practitioners in the field.     

Progressively Censored Reliability Sampling Plans for the Weibull Distribution

This article presents progressively censored variable sampling plans for the Weibull distribution. Approximate maximum likelihood estimators are developed for estimating the parameters of interest. In the construction of sampling plans, asymptotic distribution theory is used to determine the sample size and the acceptance constant. Sampling plans are tabulated for selected progressive censoring patterns and specifications, for demonstration and comparison. A Monte Carlo experiment, conducted to investigate the accuracy of the asymptotic normal approximation, has shown that the procedure is sufficiently accurate for practical purposes. An example, based on data reported by Montanari and Cacciari from progressively censored aging tests on XLPE-insulated cable models, is given for illustration.     

浅谈检测机构的人员要求

为了保证所有开展检测工作的方法科学、行为公正、数据准确和客户满意,以及为保证质量管理体系持续有效运行,并得到不断完善,必须对人员知识面、能力技术水平和实验室等素质要求做出规定,并且还必须对人员进行持续的有计划的培训。     

论计数抽样检验及应用

本文阐述了计数抽样检验的原理，给出了抽样检验方案，合格质量水平，检验水平，讨论了抽样检验的基本事实及应用。