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提出一种基于支持向量机的功率变换器开关管开路故障诊断方法。利用支持向量机建立分类模型,模型以相电流功率谱为输入量,7种故障状态为输出量,选用高斯核,使用基于二叉树分类器的分类算法。将诊断结果与基于BP神经网络的诊断结果进行比较,结果表明基于支持向量机的分类器在功率变换器开关管开路故障诊断中具有更高的准确率和更好的泛化能力。 相似文献
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This article studies a min‐max path cover problem, which is to determine a set of paths for k capacitated vehicles to service all the customers in a given weighted graph so that the largest path cost is minimized. The problem has wide applications in vehicle routing, especially when the minimization of the latest service completion time is a critical performance measure. We have analyzed four typical variants of this problem, where the vehicles have either unlimited or limited capacities, and they start from either a given depot or any depot of a given depot set. We have developed approximation algorithms for these four variants, which achieve approximation ratios of max{3 ‐ 2/k,2}, 5, max{5 ‐ 2/k,4}, and 7, respectively. We have also analyzed the approximation hardness of these variants by showing that, unless P = NP , it is impossible for them to achieve approximation ratios less than 4/3, 3/2, 3/2, and 2, respectively. We have further extended the techniques and results developed for this problem to other min‐max vehicle routing problems.© 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010 相似文献
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With the help of the Internet and express delivery at relatively low costs, trading markets have become increasingly popular as a venue to sell excess inventory and a source to obtain products at lower prices. In this article, we study the operational decisions in the presence of a trading market in a periodic‐review, finite‐horizon setting. Prices in the trading market change periodically and are determined endogenously by the demand and supply in the market. We characterize the retailers'optimal ordering and trading policies when the original manufacturer and the trading market co‐exist and retailers face fees to participate in the trading market. Comparing with the case with no trading fees, we obtain insights into the impact of trading fees and the fee structure on the retailers and the manufacturer. Further, we find that by continually staying in the market, the manufacturer may use her pricing strategies to counter‐balance the negative impact of the trading market on her profit. Finally, we extend the model to the case when retailers dynamically update their demand distribution based on demand observations in previous periods. A numerical study provides additional insights into the impact of demand updating in a trading market with the manufacturer's competition. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2010 相似文献
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中国特色网络文化建设与大学生思想政治教育 总被引:1,自引:1,他引:0
随着网络技术的发展,网络文化也运用而生。网络文化的双面效应给高校的思想政治教育工作带来了新的挑战。本文在分析网络文化对大学生影响的基础上,提出构建中国特色的网络文化,推进大学生思想政治教育的思路和措施。 相似文献
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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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新中国成立初期,人民解放军展开了学苏军活动。这次学苏军活动,经历了全面学习、有分析有批判地学习以及确立“以我为主”方针等三个历史阶段。通过学习、借鉴苏军经验,人民解放军技战术水平和协同作战能力有了很大提高,正规化现代化革命化建设取得显著成绩,同时也积累了许多值得借鉴的经验教训。 相似文献
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