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51.
We study new decision and optimization problems of finding a simple path between two given vertices in an arc weighted directed multigraph such that the path length is equal to a given number or it does not fall into the given forbidden intervals (gaps). A fairly complete computational complexity classification is provided and exact and approximation algorithms are suggested. 相似文献
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Capacity planning decisions affect a significant portion of future revenue. In the semiconductor industry, they need to be made in the presence of both highly volatile demand and long capacity installation lead‐times. In contrast to traditional discrete‐time models, we present a continuous‐time stochastic programming model for multiple resource types and product families. We show how this approach can solve capacity planning problems of reasonable size and complexity with provable efficiency. This is achieved by an application of the divide‐and‐conquer algorithm, convexity, submodularity, and the open‐pit mining problem. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005. 相似文献
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Zsolt Lazar 《Defense & Security Analysis》2019,35(3):283-307
The Soviet-led Council for Mutual Economic Assistance member, Central European countries found themselves in a difficult political and economic situation after the collapse of the Soviet Union. Three post-Eastern Bloc countries formed the Visegrad Group to strengthen their ties to the West, but the need for foreign investment, job creation and technology transfer was urgent.
This is when military modernisation also came into the picture and the counter-trade—as known as offset—as a tool to help these economies. A trade practice which was meant to energise these economies via defence acquisitions linked economic programmes.
Two Visegrad Group member countries, Hungary and the Czech Republic decided to sign offset agreement with the defence firm SAAB to license Gripen fighter aircrafts. This study intends to analyse if these deals were able to help governments to reach their objectives or the two countries were unable to take advantage of the offset programmes. 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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计算机控制抛光中基于等面积增长螺旋线的加工路径 总被引:1,自引:1,他引:1
目前计算机控制抛光工艺中使用的阿基米德螺旋线路径,存在加工工件中心区域时工件转速过快的缺点.为了克服该缺点,分析了螺旋线路径加工的特点,分析表明工件的瞬时转速取决于加工点的驻留时间密度和螺旋线的面积增长速率.据此,提出了一种新的螺旋线作为抛光路径,该螺旋线的面积增长速率恒定,因此也称为等面积增长螺旋线.利用该螺旋线路径,加工转速趋于恒定,可降低加工中心区域的转速,从而降低对机床运动性能的要求,降低设备成本和加工成本.实验结果证实,阿基米德螺旋线路径加工中心区域容易产生过加工问题,加工精度较低;等面积增长螺旋线路径加工可避免中心区域过加工问题,获得较高的加工精度. 相似文献
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面向对象的反舰导弹航路规划 总被引:1,自引:0,他引:1
针对反舰导弹航路规划的任务特点,提出了一种面向对象的反舰导弹航路规划方法。在全面分析了反舰导弹航路规划中可能用到的类的基础上,建立了对各种类的描述,使得不同算法和不同任务要求的航路规划可以通过对类的继承和对成员函数的重载实现。最后,在VC++平台下,对这种面向对象的反舰导弹航路规划方法进行了编程实验。 相似文献
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基于Multi-Agent敏捷卫星动态任务规划问题 总被引:1,自引:0,他引:1
在分析敏捷卫星的特点和卫星多用户需求的基础上,针对敏捷卫星任务规划问题,基于Multi-Agent理论构建了任务分配模型;针对敏捷卫星任务规划初始方案调度中卫星资源失效的情况给出了敏捷卫星动态任务重调度模型;在此基础上,提出了基于诚信机制的可解约合同网任务分配方法,设计了招投标机制、可解约合同网协议以及招投标、评标策略;以敏捷卫星任务规划调度问题为例通过实验获得了满意的结果,表明了模型的合理性以及算法的有效性。 相似文献