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491.
研究了任务期间允许换件维修和备件供应时k/N系统的任务完成能力.首先,利用马尔可夫过程分析了k/N系统的状态转移过程,研究了k/N系统在特定维修保障策略下的运行过程.然后,以k/N系统固定任务时间内在正常状态停留时间的分布函数作为其任务完成概率模型,并通过全概率分解和更新过程的分析方法对任务完成概率进行求解.最后,利用任务完成概率模型在Matlab中绘制了任务完成概率随任务时间、任务量、备件携行数量以及备件平均供应时间的变化曲线,讨论并分析了对任务完成概率的影响. 相似文献
492.
针对现阶段自行火炮定期维修中存在问题,为了预防自行火炮的故障以及缩短维修时间,提高自行火炮维修的针对性和有效性,在自行火炮维修中引入了基于状态的维修(Condition Based Maintenance,CBM),从工程应用的角度出发,设计并开发了自行火炮状态维修决策支持系统(CBMDSS),明确了系统设计的目标,构建了系统的总体结构,详细阐述了系统实现的具体功能,应用Visual Studio.Net及Matlab相结合的程序开发语言开发了自行火炮状态维修决策支持系统,对自行火炮开展状态维修具有十分重要的使用价值。 相似文献
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当前多数在线草图符号识别方法是在用户绘制完图形后,通过点击按钮或等待一定时间来反馈识别结果。为提供连续反馈,提出了一种基于图元的部分草图识别算法:对输入笔画进行笔画分割得到图元表示,提取表示两个图元空间关系的新特征,依据指派问题模型,通过该特征的相似度识别符号。算法简单,无须训练,而且与笔顺、笔画数和图形大小无关。实验证明了方法的有效性。 相似文献
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This article studies the problem of designing Bayesian sampling plans (BSP) with interval censored samples. First, an algorithm for deriving the conventional BSP is proposed. The BSP is shown to possess some monotonicity. Based on the BSP and using the property of monotonicity, a new sampling plan modified by the curtailment procedure is proposed. The resulting curtailed Bayesian sampling plan (CBSP) can reduce the duration time of life test experiment, and it is optimal in the sense that its associated Bayes risk is smaller than the Bayes risk of the BSP if the cost of the duration time of life test experiment is considered. A numerical example to compute the Bayes risks of BSP and CBSP and related quantities is given. Also, a Monte Carlo simulation study is performed to illustrate the performance of the CBSP compared with the BSP. The simulation results demonstrate that our proposed CBSP has better performance because it has smaller risk. The CBSP is recommended. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 604–616, 2015 相似文献
497.
Using a birth‐and‐death process to estimate the steady‐state distribution of a periodic queue 下载免费PDF全文
If the number of customers in a queueing system as a function of time has a proper limiting steady‐state distribution, then that steady‐state distribution can be estimated from system data by fitting a general stationary birth‐and‐death (BD) process model to the data and solving for its steady‐state distribution using the familiar local‐balance steady‐state equation for BD processes, even if the actual process is not a BD process. We show that this indirect way to estimate the steady‐state distribution can be effective for periodic queues, because the fitted birth and death rates often have special structure allowing them to be estimated efficiently by fitting parametric functions with only a few parameters, for example, 2. We focus on the multiserver Mt/GI/s queue with a nonhomogeneous Poisson arrival process having a periodic time‐varying rate function. We establish properties of its steady‐state distribution and fitted BD rates. We also show that the fitted BD rates can be a useful diagnostic tool to see if an Mt/GI/s model is appropriate for a complex queueing system. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 664–685, 2015 相似文献
498.
For a component or a system subject to stochastic degradation with sporadic jumps that occur at random times and have random sizes, we propose to model the cumulative degradation with random jumps using a single stochastic process based on the characteristics of Lévy subordinators, the class of nondecreasing Lévy processes. Based on the inverse Fourier transform, we derive a new closed‐form reliability function and probability density function for lifetime, represented by Lévy measures. The reliability function derived using the traditional convolution approach for common stochastic models such as gamma degradation process with random jumps, is revealed to be a special case of our general model. Numerical experiments are used to demonstrate that our model performs well for different applications, when compared with the traditional convolution method. More importantly, it is a general and useful tool for life distribution analysis of stochastic degradation with random jumps in multidimensional cases. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 483–492, 2015 相似文献
499.
The dynamic and stochastic knapsack Problem with homogeneous‐sized items and postponement options 下载免费PDF全文
This article generalizes the dynamic and stochastic knapsack problem by allowing the decision‐maker to postpone the accept/reject decision for an item and maintain a queue of waiting items to be considered later. Postponed decisions are penalized with delay costs, while idle capacity incurs a holding cost. This generalization addresses applications where requests of scarce resources can be delayed, for example, dispatching in logistics and allocation of funding to investments. We model the problem as a Markov decision process and analyze it through dynamic programming. We show that the optimal policy with homogeneous‐sized items possesses a bithreshold structure, despite the high dimensionality of the decision space. Finally, the value (or price) of postponement is illustrated through numerical examples. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 267–292, 2015 相似文献
500.