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111.
This article examines challenges in international nuclear safeguards pertaining to the timely detection of highly enriched uranium production at large-scale gas centrifuge enrichment plants. To establish where present gas centrifuge enrichment plant safeguards measures and approaches could be strengthened, we have created a discrete time model for simulating hypothetical misuse scenarios, both through transient phases and at steady-state. We find that timely detection of misuse at modern large-scale facilities presents a challenge for international safeguards. A toolbox of unattended measurement systems, along with remote monitoring, however, could be used to improve detection timeliness, enabling the initiation of follow-up activities, potentially on a rapid time scale. These measures, which would need very low false alarm rates, should be implemented in a graded approach, depending on the characteristics of each enrichment plant and an analysis of plausible acquisition paths for the State in which it is situated. Some of these technologies could provide significant benefit to plant operators. 相似文献
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In this article, we address a stochastic generalized assignment machine scheduling problem in which the processing times of jobs are assumed to be random variables. We develop a branch‐and‐price (B&P) approach for solving this problem wherein the pricing problem is separable with respect to each machine, and has the structure of a multidimensional knapsack problem. In addition, we explore two other extensions of this method—one that utilizes a dual‐stabilization technique and another that incorporates an advanced‐start procedure to obtain an initial feasible solution. We compare the performance of these methods with that of the branch‐and‐cut (B&C) method within CPLEX. Our results show that all B&P‐based approaches perform better than the B&C method, with the best performance obtained for the B&P procedure that includes both the extensions aforementioned. We also utilize a Monte Carlo method within the B&P scheme, which affords the use of a small subset of scenarios at a time to estimate the “true” optimal objective function value. Our experimental investigation reveals that this approach readily yields solutions lying within 5% of optimality, while providing more than a 10‐fold savings in CPU times in comparison with the best of the other proposed B&P procedures. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 131–143, 2014 相似文献
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1 This paper presents an empirical analysis of what drives congressional legislation on terrorism during the period 1995 to 2010. We utilize and augment current methodology to compile and analyze data on sponsorship and cosponsorship of terrorism related data. Our results on the sources of legislation on terrorism are largely in line with past examinations of the importance of committee membership and leadership, party majority-ship, and other political factors. Further, we find that the most significant and robust drive for legislation on terrorism is the September 11th attacks. And while the impact of 9/11 affected legislative productivity everywhere, we find that it most significantly affected states surrounding New York and Washington D.C. Our results indicate that the economy may be one factor motivating politicians to legislate on terrorism; however, these results are not robust. 相似文献
114.
Kenneth D. Ward 《The Nonproliferation Review》2013,20(2):183-199
The stage may be set for what could be a historic turning point in America's reliance on nuclear weapons to meet its fundamental national security interests. Proponents of a refurbished nuclear stockpile and infrastructure are convinced that nuclear weapons will remain central to U.S. security interests, yet they admit that there is no national consensus on the need for and role of nuclear weapons. Nuclear opponents are gravely concerned that to the extent nuclear refurbishment creates a global perception that nuclear weapons remain essential instruments, it will eviscerate nuclear nonproliferation measures precisely at a time when nuclear ambitions are growing. Moreover, opponents see deterrence through advanced conventional weapons as decisively more credible than any nuclear alternative. With hopes of elevating discourse to the national level, this article examines the key current arguments pro and con within the specialist community and forecasts changes in the U.S. nuclear arsenal over the next decade. It concludes with a brief prognosis on prospects for complete nuclear disarmament. 相似文献
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Paul F. Walker 《The Nonproliferation Review》2013,20(3-4):517-525
ABSTRACTThe recent use of chemicals in warfare in Syria and Iraq illustrates that, despite the important work of the 1997 Chemical Weapons Convention (CWC), the world has not yet been totally successful in stopping the use of indiscriminate toxic agents in conflicts, either by states or non-state actors. Michael Crowley's excellent and timely new book, Chemical Control, analyzes the use of “riot control agents” (RCAs) and “incapacitating chemical agents” (ICAs), including launch and dispersal systems, by police, paramilitary, and military forces over the last decades and raises the challenging question about where the red line might be drawn between banned and permitted uses of chemicals. He discusses this problem not only in the context of the CWC, which allows use of RCAs for civilian riot control, but also in the context of international law, human rights, and criminal justice, including the Biological and Toxin Weapons Convention and other disarmament and abolition regimes. He proposes a “holistic, three-stage approach” to addressing this issue “for effective regulation or prohibition of the weapon or weapon-related technology of concern.” As we approach the global abolition of a whole class of weapons of mass destruction in the next decade or even sooner, Chemical Control is helpful in better understanding and solving the dilemma of what's actually banned or permitted under international law, and precluding states undermining the chemical weapons ban. 相似文献
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Full‐system testing for large‐scale systems is often infeasible or very costly. Thus, when estimating system reliability, it is desirable to use a method that uses subsystem tests, which are often less expensive and more feasible. This article presents a method for bounding full‐system reliabilities based on subsystem tests and, if available, full‐system tests. The method does not require that subsystems be independent. It accounts for dependencies through the use of certain probability inequalities. The inequalities provide the basis for valid reliability calculations while not requiring independent subsystems or full‐system tests. The inequalities allow for test information on pairwise subsystem failure modes to be incorporated, thereby improving the bound on system reliability. We illustrate some of the properties of the estimates via an example application. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013 相似文献
120.
John D. Waghelstein 《Small Wars & Insurgencies》2013,24(3):360-378
The Lord's Resistance Army (LRA) has created a pervasive climate of fear in northern Uganda. This study addresses the purpose of this conduct. Diverging from the traditional ‘greed-grievance’ approach to the study of new wars, the LRA's behaviour is analyzed from a strategic perspective. Specifically, the article focuses on the LRA's use of mutilation, abduction, surprise, and unpredictable attacks. The conclusion is that the LRA is strategically using fear as a force multiplier, to further its organizational survival, and as a way to fight a political ‘dirty war’. 相似文献