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Suzanne E. Spaulding 《The Nonproliferation Review》2013,20(4):168-178
The threat posed by the proliferation of weapons of mass destruction is real and urgent. Combating this threat requires a new and comprehensive approach by the federal government. It requires sustained leadership at the top and an organizational structure that can set policies and objectives for combating proliferation; develop integrated, government‐wide plans to implement those policies and objectives, including plans for acquiring necessary technology; make appropriate decisions regarding how resources should be allocated to carry out those plans; and regularly evaluate the effectiveness of our policies, programs, and operations. There is no such comprehensive approach today. 相似文献
414.
Timothy D. Sisk 《Civil Wars》2013,15(4):7-20
Syria's slide into sectarian civil war in 2011 raises a new fundamental knowledge question about the conditions under which power-sharing pacts can be clinched as an approach to war termination. When intrastate conflicts escalate into violent sectarian struggles, power-sharing is a likely basis of an eventual political settlement in situations where partition is off the table. This article contends that there remain two puzzling knowledge gaps about power-sharing as the basis for peace agreements to end civil wars: first, the specific conditions under which elites find it in their own interest to share power with bitter adversaries rather than fight on the battlefield, and second, how war-ending elite-negotiated pacts may evolve into more enduring social contracts. These puzzles, critical for policymakers and still unresolved in the scholarly literature, suggest the need to develop more contingent- and context-specific knowledge if research findings are to more capably contribute to peacemaking efforts. 相似文献
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This article proposes two dual‐ascent algorithms and uses each in combination with a primal drop heuristic embedded within a branch and bound framework to solve the uncapacitated production assembly distribution system (i.e., supply chain) design problem, which is formulated as a mixed integer program. Computational results indicate that one approach, which combines primal drop and dual‐ascent heuristics, can solve instances within reasonable time and prescribes solutions with gaps between the primal and dual solution values that are less than 0.15%, an efficacy suiting it for actual large‐scale applications. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2013 相似文献
417.
Demand forecasting performance is subject to the uncertainty underlying the time series an organization is dealing with. There are many approaches that may be used to reduce uncertainty and thus to improve forecasting performance. One intuitively appealing such approach is to aggregate demand in lower‐frequency “time buckets.” The approach under concern is termed to as temporal aggregation, and in this article, we investigate its impact on forecasting performance. We assume that the nonaggregated demand follows either a moving average process of order one or a first‐order autoregressive process and a single exponential smoothing (SES) procedure is used to forecast demand. These demand processes are often encountered in practice and SES is one of the standard estimators used in industry. Theoretical mean‐squared error expressions are derived for the aggregated and nonaggregated demand to contrast the relevant forecasting performances. The theoretical analysis is supported by an extensive numerical investigation and experimentation with an empirical dataset. The results indicate that performance improvements achieved through the aggregation approach are a function of the aggregation level, the smoothing constant, and the process parameters. Valuable insights are offered to practitioners and the article closes with an agenda for further research in this area. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 60: 479–498, 2013 相似文献
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By running life tests at higher stress levels than normal operating conditions, accelerated life testing (ALT) quickly yields information on the lifetime distribution of a test unit. The lifetime at the design stress is then estimated through extrapolation using a regression model. In constant‐stress testing, a unit is tested at a fixed stress level until failure or the termination time point of test, whereas step‐stress testing allows the experimenter to gradually increase the stress levels at some prefixed time points during the test. In this work, the optimal k‐level constant‐stress and step‐stress ALTs are compared for the exponential failure data under complete sampling and Type‐I censoring. The objective is to quantify the advantage of using the step‐stress testing relative to the constant‐stress one. Assuming a log‐linear life–stress relationship with the cumulative exposure model for the effect of changing stress in step‐stress testing, the optimal design points are determined under C/D/A‐optimality criteria. The efficiency of step‐stress testing to constant‐stress one is then discussed in terms of the ratio of optimal objective functions based on the information matrix. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 00: 000–000, 2013 相似文献
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F. G. Hoffman John Bew David French Nicolas Lewkowicz Thomas Rid Paul Staniland 《战略研究杂志》2013,36(5):777-795
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Ranan D. Kuperman 《战略研究杂志》2013,36(1):1-2
Israel's policy of military reprisals has never seemed to follow any consistent pattern of tit‐for‐tat. On the one hand, not every violent incident was answered with a counterattack. On the other hand, when Israel responded, frequently it employed an excessive amount of force, which was disproportional to the Arab provocation. This behavior has not been the consequence of a premeditated and rational strategy. Instead, it appears to have been the result of a political dispute between alternative approaches regarding the use of military force. The following research analyzes the development of this controversy and how these differences of opinion were resolved. 相似文献