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States confronting cross-border intrusions of terrorism, illegal immigration, and/or drug trafficking weigh the costs of such intrusions against the costs of imposing barriers to prevent or curb the intrusions. In such situations, the degree of national security afforded a state depends, in large measure, upon the degree of border openness the state chooses. Depending upon the intensity and frequency of the intrusions – expressed in terms of opportunity-cost functions – a state might have little choice but to pursue a border policy of zero openness. It is this relationship of border openness to national security that explains why many states choose to construct security fences. In the 49 cases of security fences examined, many – among them Israel vis-à-vis the West Bank, India vis-à-vis Pakistan, Turkey vis-à-vis Greece in Cyprus – the construction of security fences becomes more complicated by their placement on lands whose sovereignties are disputed. 相似文献
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This study examines the failures of the William J. Clinton and Barack Obama administrations to secure ratification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). It applies an integrated analytical framework for assessing treaty ratification that builds upon previous research in order to understand why the Clinton administration failed to achieve CTBT ratification in 1999 and why the Obama administration has so far failed to advance the treaty in the Senate. The study concludes that CTBT ratification, despite Obama administration pledges of support, remains highly unlikely. Finally, the study analyzes the common domestic political factors present in both cases and suggests areas for further research. 相似文献
305.
We study a stochastic interdiction model of Morton et al. IIE Transactions, 39 (2007):3–14 that locates radiation sensors at border crossings to detect and prevent the smuggling of nuclear material. In this model, an interdictor places sensors at customs checkpoints to minimize a potential smuggler's maximum probability of crossing a border undetected. We focus on a model variant in which the interdictor has different, and likely more accurate, perceptions of the system's parameters than the smuggler does. We introduce a model that is tighter and uses fewer constraints than that of Morton et al. We also develop a class of valid inequalities along with a corresponding separation procedure that can be used within a cutting‐plane approach to reduce computational effort. Computational results demonstrate the effectiveness of our approach.Copyright © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 91–100, 2014 相似文献
306.
A mathematical formulation and efficient heuristics for the dynamic container relocation problem 下载免费PDF全文
The container relocation problem (CRP) is concerned with emptying a single yard‐bay which contains J containers each following a given pickup order so as to minimize the total number of relocations made during their retrieval process. The CRP can be modeled as a binary integer programming (IP) problem and is known to be NP‐hard. In this work, we focus on an extension of the CRP to the case where containers are both received and retrieved from a single yard‐bay, and call it the dynamic container relocation problem. The arrival (departure) sequences of containers to (from) the yard‐bay is assumed to be known a priori. A binary IP formulation is presented for the problem. Then, we propose three types of heuristic methods: index based heuristics, heuristics using the binary IP formulation, and a beam search heuristic. Computational experiments are performed on an extensive set of randomly generated test instances. Our results show that beam search heuristic is very efficient and performs better than the other heuristic methods.Copyright © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 101–118, 2014 相似文献
307.
What explains the pace at which militaries adopt new technology? We argue that the hierarchical structure and unique expertise requirements of military organizations combine to empower select individuals as ‘gatekeepers’ of innovation. These individuals acquire beliefs throughout their military careers regarding the nature and means of warfare that act to shape their attitudes towards new military innovations. By filtering, sidelining, and ignoring competing sources of advice and information, these officers actively inhibit the adoption of new, often advantageous, innovations. We develop this argument through the analysis of two cases: the delayed acquisition of breech-loading and repeating rifles by the Union Army during the American Civil War, and the failure of the US Army to adopt an adequate heavy-type tank in World War II. 相似文献
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The anthrax attacks of 2001 energized research directed toward reducing health consequences from airborne contaminants by augmenting current heating ventilation and air-conditioning (HVAC) systems. Even during peacetime, interest will continue in improving HVAC components to reduce biocontaminants associated with sick building syndrome. Current HVAC design uses numerical simulation methods of ordinary differential equations to predict approximate performance. The authors show that state-space Laplace Transform calculations actually solve the underlying differential equations and yield algebraic expressions that provide new insight. To sharpen the arguments in favor of this methodology, attention is restricted to improving existing HVAC systems to increase protection from an external release of hazardous particulates. By nearly eliminating the need for dynamical simulation, the resulting methods can be applied to far more complex HVAC designs with little additional computational effort. The new methods reduce the time required for computation by three orders of magnitude. These algebraic methods also can be extended to disparate technical problems including internal particulate release, gas masks, and designing new protective buildings. 相似文献
309.
Thomas W. Lucas W. David Kelton Paul J. Sánchez Susan M. Sanchez Ben L. Anderson 《海军后勤学研究》2015,62(4):293-303
Decades ago, simulation was famously characterized as a “method of last resort,” to which analysts should turn only “when all else fails.” In those intervening decades, the technologies supporting simulation—computing hardware, simulation‐modeling paradigms, simulation software, design‐and‐analysis methods—have all advanced dramatically. We offer an updated view that simulation is now a very appealing option for modeling and analysis. When applied properly, simulation can provide fully as much insight, with as much precision as desired, as can exact analytical methods that are based on more restrictive assumptions. The fundamental advantage of simulation is that it can tolerate far less restrictive modeling assumptions, leading to an underlying model that is more reflective of reality and thus more valid, leading to better decisions. Published 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 293–303, 2015 相似文献
310.
Revenue management is the process of actively managing inventory or capacity to maximize revenues. The active management typically occurs through managerial levers such as price, promotion, or availability. We present a novel real options approach to revenue management that is specifically suited to the car rental business. We illustrate the concept with actual car rental data. The model produces minimally acceptable prices and inventory release quantities (number of cars available for rent at a given price) as a function of remaining time and available inventory. The pricing and inventory release recommendations of the developed model confirm earlier empirical analysis that suggested current practises discount too deeply early in the booking cycle. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004 相似文献