Monitoring process mean using generally weighted moving average chart for exponentially distributed characteristics

In this article, we will present a control chart using normal transformation and generally weighted moving average (GWMA) statistic when the quality characteristic follows the exponential distribution. We will develop the necessary measures to monitor the mean of the process using GWMA statistic and analyze the performance using simulation. The average run lengths for monitoring process average are given for various process shifts. The performance of the proposed chart is examined and compared with the existing control chart. The proposed control chart is effective for the monitoring of small shifts in the mean process. The application of the proposed chart is illustrated with the help of simulated data.     

Control charts for generalized exponential distribution percentiles

The generalized exponential (GE) distribution, which was introduced by Mudholkar and Srivastava in 1993 Mudholkar, G. S., Srivastava, D. K. (1993). Exponentiated Weibull family for analyzing bathtub failure data. IEEE Transactions on Reliability 42:299–302. [Google Scholar], has been studied for various applications of lifetime modelings. In this article, five control charts, that comprise the Shewhart-type chart and four parametric bootstrap charts based on maximum likelihood estimation method, the moment estimation method, probability plot method, and least-square error method for the GE percentiles, are investigated. An extensive Monte Carlo simulation study is conducted to compare the performance among all five control charts in terms of average run length. Finally, an example is given for illustration.     

Fast computing for dynamic screening systems when analyzing correlated data

In practice, we often need to identify individuals whose longitudinal behaviour is different from the behaviour of those well-functioning individuals, so that some unpleasant consequences (e.g. stroke) can be avoided or early detected. To handle such applications, a new statistical method, called dynamic screening system, has been developed in the literature. A recent version of this method can analyze correlated data. However, the computation involved is intensive. In this paper, we suggest a fast computing algorithm for the dynamic screening system. The algorithm can improve the effectiveness of the conventional dynamic screening system in certain cases. Numerical results show that the new algorithm works well in different cases.     

An alternative to confidence intervals constructed after a Hausman pretest in panel data

Consider panel data modelled by a linear random intercept model that includes a time‐varying covariate. Suppose that our aim is to construct a confidence interval for the slope parameter. Commonly, a Hausman pretest is used to decide whether this confidence interval is constructed using the random effects model or the fixed effects model. This post‐model‐selection confidence interval has the attractive features that it (a) is relatively short when the random effects model is correct and (b) reduces to the confidence interval based on the fixed effects model when the data and the random effects model are highly discordant. However, this confidence interval has the drawbacks that (i) its endpoints are discontinuous functions of the data and (ii) its minimum coverage can be far below its nominal coverage probability. We construct a new confidence interval that possesses these attractive features, but does not suffer from these drawbacks. This new confidence interval provides an intermediate between the post‐model‐selection confidence interval and the confidence interval obtained by always using the fixed effects model. The endpoints of the new confidence interval are smooth functions of the Hausman test statistic, whereas the endpoints of the post‐model‐selection confidence interval are discontinuous functions of this statistic.     

有限尺寸介质基片上的共面带线

讨论了厚度和宽度都为有限尺寸的介质基片上共面带线的基本参数;有限尺寸介质基片上的共面带线是一种非常接近于工程应用状态的物理模型。用共形映射技术分析这种共面带线,得到了单位长度电容、有效介电常数和特性阻抗等基本参数;与介质基片宽度为无限大的理想化模型作了比较;给出了以无限宽介质基片共面带线作近似模型,介质基片宽度变化所产生的误差;讨论了多层有限尺寸介质基片上的共面带线     

带有维修和等待制的M／G／1可修排队系统

讨论了带有维修和等待制的Ｍ／Ｇ／１可修排队系统。在假定服务台的寿命有负指数分布，修理时间和维修时间均有一般分布的情况下，使用嵌入马尔柯夫链和文献［１］提出的分解法，获得队长和等待时间的随机分解结果，以及服务台的可靠性指标。     

衡量突发交换系统的新指标

长期以来一直沿用平均比特剪切率(BCR)来描述突发交换(Burst Switching 或 BS)系统的话音性能,本文在指出了单用 BCR 描述 BS 系统话音性能的不足之处后,提出了一个协同 BCR 评价 BS 系统话音性能的新指标—平均话段剪切长度(mean Burst Clipping Lcngth 或 BCL)。接着,详细分析了 BS系统中话段受剪切的过程,推导出了话段剪切长度的概率分布及平均值的计算公式,并用计算机模拟对这些公式进行了验证。     

Lattice paths combinatorics applied to transient queue length distribution of C2/M/1 queues and busy period analysis of bulk queues C2/M/1

This paper aims at deriving explicit transient queue length distribution for GI/M/1 system and busy period analysis of bulk queue GI^b/M/1 through lattice paths (LPs) combinatorics. The general interarrival time distribution is approximated by two-phase Cox distribution, C₂, that has Markovian property, enabling us to represent the processes by two-dimensional LPs. As distributions C₂ cover a wide class of distributions that have rational Laplace–Stieltjes transforms (LSTs) with square coefficient of variation lying in , the results obtained are applicable to a large class of real life situations. Some numerical results for the C₂^b/M/1 model are also given.