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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
344.
As a complex system with multiple components usually deteriorates with age, preventive maintenance (PM) is often performed to keep the system functioning in a good state to prolong its effective age. In this study, a nonhomogeneous Poisson process with a power law failure intensity is used to describe the deterioration of a repairable system, and the optimal nonperiodic PM schedule can be determined to minimize the expected total cost per unit time. However, since the determination of such optimal PM policies may involve numerous uncertainties, which typically make the analyses difficult to perform because of the scarcity of data, a Bayesian decision model, which utilizes all available information effectively, is also proposed for determining the optimal PM strategies. A numerical example with a real failure data set is used to illustrate the effectiveness of the proposed approach. The results show that the optimal schedules derived by Bayesian approach are relatively more conservative than that for non‐Bayesian approach because of the uncertainty of the intensity function, and if the intensity function are updated using the collected data set, which indicates more severe deterioration than the prior belief, replacing the entire system instead of frequent PM activities before serious deterioration is suggested. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010 相似文献
345.
We consider a finite horizon periodic review, single product inventory system with a fixed setup cost and two stochastic demand classes that differ in their backordering costs. In each period, one must decide whether and how much to order, and how much demand of the lower class should be satisfied. We show that the optimal ordering policy can be characterized as a state dependent (s,S) policy, and the rationing structure is partially obtained based on the subconvexity of the cost function. We then propose a simple heuristic rationing policy, which is easy to implement and close to optimal for intensive numerical examples. We further study the case when the first demand class is deterministic and must be satisfied immediately. We show the optimality of the state dependent (s,S) ordering policy, and obtain additional rationing structural properties. Based on these properties, the optimal ordering and rationing policy for any state can be generated by finding the optimal policy of only a finite set of states, and for each state in this set, the optimal policy is obtained simply by choosing a policy from at most two alternatives. An efficient algorithm is then proposed. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010 相似文献
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在相容关系下定义了三种不完备条件熵——H′条件熵、E′条件熵和I′条件熵,并对它们的性质进行了分析比较,研究发现,H′条件熵和I′条件熵不适用于相容关系下信息观点的约简。利用E′条件熵刻画信息系统中属性的相对重要性,设计了一种新的基于信息论观点的启发式约简算法,它统一了完备信息系统与非完备信息系统中的约简方法。通过实例说明,该算法能得到决策表的相对约简。 相似文献
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地理信息系统专业实践教学体系研究 总被引:2,自引:0,他引:2
实践教学是GIS专业教学至关重要的环节。结合GIS知识体系结构、专业特点和社会需求,讨论了GIS专业实践教学体系的基本框架及其依托。 相似文献
348.
柯健 《兵团教育学院学报》2010,20(1):31-36
社会主义核心价值体系是社会主义意识形态的本质体现。马克思主义指导思想是社会主义核心价值体系的旗帜与灵魂。社会主义核心价值体系是中国共产党领导人民建设中国特色社会主义的共同价值追求;以爱国主义为核心的民族精神和以改革创新为核心的时代精神是社会主义核心价值体系的精髓;弘扬以改革创新为核心的时代精神是建设社会主义核心价值体系的根本途径;大力弘扬以改革创新为核心的时代精神是实现中华民族伟大复兴的强大动力。 相似文献
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针对多故障样本一次性映射之后分类不理想,研究了多级层次式支持向量机,应用UCI数据仿真,结果表明该方法缩短了训练时间、提升了测试准确率、改善了样本的可分类性。由于误差积累,在此基础上,提出了层间嵌入式多级支持向量机,采用Abalone数据仿真,结果表明分类精度有所提高并减少了分类步骤。结合ReliefF算法,对制导设备的故障特征参数进行了选择。 相似文献
350.
针对作战单元维修保障能力评估的需求,提出建立基于HLA的维修保障仿真分析平台。在分析维修保障系统构成和运行过程的基础上,阐述了仿真联邦的设计思想和构建方法,并进行了系统设计。根据实际系统的运行逻辑开发了联邦剧情,基于HLA的开发和执行过程模型构建了联邦系统框架,设计了联邦对象模型,并指出了仿真实现的关键技术所在。 相似文献