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During the last decade telecommunication operators have been deploying WDM (Wavelength Division Multiplexing) technology to satisfy the exponential growth in global communication. While facilitating the advanced information society of today, this has also led to a higher dependency on the networks, and furthermore the high capacity utilization of optical fibers means that a single link failure will influence many users and enterprises. For these reasons, protection of network connections has become a major competitive parameter for the operators. Currently, the most popular protection method is ring protection, due to its simplicity, requiring only basic management functionality and operating with local restoration control. While many optical rings have been deployed, little work has been published on exactly what the cost of ring networks are, compared to general mesh networks. In this article we perform a quantitative comparison between ring protection and mesh protection, using real world network data and realistic prices for network components. Extending classic LP flow models to take rings and node costs into account, and using a link‐path based mesh network LP model, we are able to perform a total cost comparison of the two architectures, and of manual ring network design. The results suggest that the price of mesh network components must be reduced significantly to be competitive with ring based networks, and also that manual network design does not necessarily lead to the most cost‐efficient designs. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2005 相似文献
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Robert R. Tomes 《Defense & Security Analysis》2012,28(4):303-315
Facing nearly half a billion dollars in spending cuts over the next five years, US defense planners and strategists must simultaneously rebuild a war-weary Army weakened from over a decade of war, build new sea and air capabilities for the Pacific theater, and reduce manpower, procurement, and contractor budgets while promoting innovation. The US defense department is embarking on what may be the most sweeping period of defense transformation in recent memory. This article reviews the history of American defense transformation, focusing on an important but largely overlooked period of military innovation that began in the shadow of Vietnam and ended with troops fighting through blinding sandstorms at night on the road to Baghdad. The multifaceted transformation strategy conceived in the 1970s paved the way for a military revolution in the 1990s and enabled unprecedented battlefield adaptation in the 2000s. After reviewing the revolutionary changes that led to American dominance in conventional warfare in the 1990s, the article examines US transformation policies in the 2000s to inform defense strategy and planning efforts in the 2010s. 相似文献
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Thomas Stow Wilkins 《战略研究杂志》2013,36(6):1121-1150
This article sets forth a framework for analysis designed to enhance our understanding of the political management of coalition warfare. The framework, based upon literature appertaining to ‘intra-alliance politics’ and International Relations (IR) theories, is applied to the case study of the Normandy Campaign of 1944. Utilising this framework we are able to consider many of the thorny issues of coalition politics and determine how these can be managed successfully to maintain Allied cohesion. Throughout the analysis the merits of the ‘realist’ and ‘pluralist’ views on maintaining Allied cohesion are appraised. The article concludes that, while both afford convincing explanations for overcoming tensions within the coalition, the pluralist approach proves superior in accounting for Allied unity. Overall, the article demonstrates that the intra-alliance politics framework is a useful device for understanding the political dynamics of the Normandy Campaign in 1944 and that it is also potentially applicable to other instances of coalition warfare; past, present, and future. 相似文献
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R.T. Stearn Editor John T. Fishel Paul Y. Hammond Thomas R. Mockaitis 《Small Wars & Insurgencies》2013,24(3):426-434
Ian Castle and Ian Knight, Fearful Hard Times: The Siege and Relief of Eshowe, 1879. Greenhill Books, London 1994, Pp.256, 85 illus, 6 maps, index. £17.95. ISBN 1–85367–180–0. Michael E. Brown (ed.), Ethnic Conflict and International Security. Princeton: Princeton University Press, 1993, Pp.263, selected biblio, index. $45/£30 (cloth); $14.95/£12.95 (paper). ISBN 0–691–03368 and 00068–9. Deborah Poole and Gerardo Renique, Peru: Time of Fear. London: Latin American Bureau (Research and Action) Ltd., 1992. Pp.212, 7 maps, photographs, glossary, sources/further reading, index. £17.99 ISBN 0–906156–70‐X and ‐71–8. David A. Charters (ed.), Peacekeeping and the Challenge of Civil Conflict Resolution. Center for Conflict Studies, University of New Brunswick, 1994. Pp.viii+220. NP. Joachim Remak, A Very Civil War: The Swiss Sonderbund War of 1847. Boulder, Colorado: Westview Press, 1993. Pp.xvi+221, 6 map's, 68 illus, biblio, index. $24.95/£16.95. 相似文献
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Accelerated life testing (ALT) is commonly used to obtain reliability information about a product in a timely manner. Several stress loading designs have been proposed and recent research interests have emerged concerning the development of equivalent ALT plans. Step‐stress ALT (SSALT) is one of the most commonly used stress loadings because it usually shortens the test duration and reduces the number of required test units. This article considers two fundamental questions when designing a SSALT and provides formal proofs in answer to each. Namely: (1) can a simple SSALT be designed so that it is equivalent to other stress loading designs? (2) when optimizing a multilevel SSALT, does it degenerate to a simple SSALT plan? The answers to both queries, under certain reasonable model assumptions, are shown to be a qualified YES. In addition, we provide an argument to support the rationale of a common practice in designing a SSALT, that is, setting the higher stress level as high as possible in a SSALT plan. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2013 相似文献
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Many authors contend that ethnic extremism coupled with political manipulation were the primary factors behind the Rwandan genocide. Yet, to oversimplify the cause of this tragedy makes one blind to the complicated nexus that generated the outcome. Even though this genocide was quick in its execution, the events that lead to this massacre took years to unfold. We argue that the evolution of human capital and the competition for scarce resources contributed to the genocide. 相似文献