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This study investigates the statistical process control application for monitoring queue length data in M/G/1 systems. Specifically, we studied the average run length (ARL) characteristics of two different control charts for detecting changes in system utilization. First, the nL chart monitors the sums of successive queue length samples by subgrouping individual observations with sample size n. Next is the individual chart with a warning zone whose control scheme is specified by two pairs of parameters, (upper control limit, du) and (lower control limit, dl), as proposed by Bhat and Rao (Oper Res 20 (1972) 955–966). We will present approaches to calculate ARL for the two types of control charts using the Markov chain formulation and also investigate the effects of parameters of the control charts to provide useful design guidelines for better performance. Extensive numerical results are included for illustration. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011 相似文献
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We consider the infinite horizon serial inventory system with both average cost and discounted cost criteria. The optimal echelon base‐stock levels are obtained in terms of only probability distributions of leadtime demands. This analysis yields a novel approach for developing bounds and heuristics for optimal inventory control polices. In addition to deriving the known bounds in literature, we develop several new upper bounds for both average cost and discounted cost models. Numerical studies show that the bounds and heuristic are very close to optimal.© 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007 相似文献
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Joseph O. Chapa 《Journal of Military Ethics》2017,16(3-4):256-271
In this paper I argue that a remotely piloted aircraft (RPA) pilot’s act of killing remotely, when it is done in the defense of another person, can be viewed as an act of sacrifice. This argument concludes from two premises. First, the RPA pilot faces psychological risk to self by carrying out such an action; second, the RPA pilot is motivated to some significant degree by something other than self-interest. Moreover, I challenge both the view that RPA represent merely an incremental development in technology yielding an incremental expansion of the distance between the war-fighter and the target and the view that RPA is revolutionary in some fundamental sense. I instead argue that, based upon the natural geometric boundary imposed by the earth’s shape, RPA have maximized the physical distance between the war-fighter and the target and, over time, this fact will change, not only the psychological effects on the RPA pilot, but also the way we view killing and distance in general. When taken together, these two broad claims, that other-defense can justify killing in war and that there is a psychological cost paid by remote killers, yield a conception of remote killing as an act of sacrifice that will inform the broader conversation about ethics, risk, killing, and RPA. 相似文献
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In this article, we study aging properties of parallel and series systems with a random number of components. We show that the decreasing likelihood ratio property is closed under the formation of random minima. We also show, by counterexamples, that other aging properties are not closed under the formation of random minima or maxima. Some mistakes in the literature are corrected. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 238–243, 2014 相似文献
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We consider a general linear filtering operation on an autoregressive moving average (ARMA) time series. The variance of the filter output, which is an important quantity in many applications, is not known with certainty because it depends on the true ARMA parameters. We derive an expression for the sensitivity (i.e., the partial derivative) of the output variance with respect to deviations in the model parameters. The results provide insight into the robustness of many common statistical methods that are based on linear filtering and also yield approximate confidence intervals for the output variance. We discuss applications to time series forecasting, statistical process control, and automatic feedback control of industrial processes. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010 相似文献
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提出了信号时域平均处理的新算法,解决了周期截断误差对平均结果的影响,并对测取的齿轮箱齿轮故障振动信号进行了处理。实验结果表明:该方法在齿轮故障信号的处理中能够消除背景噪声的影响,取得比较理想的效果。 相似文献
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信息熵是描述信息系统的一种比较成功的方法.采用信息论的方法对决策系统进行描述,在考虑了决策者的有界合理性限制和达到满意性能指标的要求下,分析了单人指挥决策系统的系统性能,并在此基础上分析了多人指挥决策系统的系统性能,最后得出采用决策系统的误差概率P和相互一致性度量Q作为评价C3I系统决策性能标准的结论. 相似文献
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