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401.
In this article, we study reliability properties of m‐consecutive‐k‐out‐of‐n: F systems with exchangeable components. We deduce exact formulae and recurrence relations for the signature of the system. Closed form expressions for the survival function and the lifetime distribution as a mixture of the distribution of order statistics are established as well. These representations facilitate the computation of several reliability characteristics of the system for a given exchangeable joint distribution or survival function. Finally, we provide signature‐based stochastic ordering results for the system's lifetime and investigate the IFR preservation property under the formulation of m‐consecutive‐k‐out‐of‐n: F systems. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011 相似文献
402.
本文分析了插值型代理模型的特性,提出了影响插值代理模型的推广能力的重要因素是代理模型的振荡特性,分析表明:振荡剧烈的代理模型,其推广能力就弱。为了评价代理模型的推广能力,本文提出基于能量函数方法的评价方法。能量函数方法是通过计算代理模型的一阶和二阶导数,得出代理模型的振荡情况来进行评价。能量函数越高,代理模型的振荡越剧烈,因而其推广能力越差。测试函数表明,能量函数方法在评价代理模型推广能力上是有效的。 相似文献
403.
This article considers the problem of monitoring Poisson count data when sample sizes are time varying without assuming a priori knowledge of sample sizes. Traditional control charts, whose control limits are often determined before the control charts are activated, are constructed based on perfect knowledge of sample sizes. In practice, however, future sample sizes are often unknown. Making an inappropriate assumption of the distribution function could lead to unexpected performance of the control charts, for example, excessive false alarms in the early runs of the control charts, which would in turn hurt an operator's confidence in valid alarms. To overcome this problem, we propose the use of probability control limits, which are determined based on the realization of sample sizes online. The conditional probability that the charting statistic exceeds the control limit at present given that there has not been a single alarm before can be guaranteed to meet a specified false alarm rate. Simulation studies show that our proposed control chart is able to deliver satisfactory run length performance for any time‐varying sample sizes. The idea presented in this article can be applied to any effective control charts such as the exponentially weighted moving average or cumulative sum chart. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 60: 625–636, 2013 相似文献
404.
HLA仿真中,数据分发管理实现基于值的过滤,可以有效减少盟员接收冗余数据的可能性和网络中的数据流量。大规模HLA仿真系统在仿真推进中需要大量的区域匹配计算以维护数据分发管理的正确性。现有的区域匹配算法大多需要对所有区域进行匹配计算,造成了大量计算资源的浪费;同时,主要基于串行匹配思想,难以充分发挥多核平台的并行计算优势。针对现有区域匹配算法的局限性,提出了一种面向大规模HLA仿真的并行区域匹配算法,该算法能够实现对一次仿真推进中多个改变区域的并行匹配计算,同时在匹配计算中采用基于移动相交的基本思想,利用区域范围移动前后的历史信息,将匹配限定在移动区间之内,减少了大量的无关计算。理论分析与实验结果表明该算法尤其适合基于多核计算平台构建大规模分布式仿真的应用需求。 相似文献
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Yun Zhou 《The Nonproliferation Review》2013,20(2):347-363
Nuclear energy is an integral part of China's energy strategy and will increasingly contribute to China's total energy supply. China has more than twenty civilian facilities, including power reactors, mines, and enrichment plants, to support its nuclear power program. As China operates more nuclear plants, more nuclear materials will be produced and stockpiled, and more nuclear facilities will be spread around the country. To ensure that this expanded network of nuclear facilities does not increase the risk that nuclear materials will be diverted or become the target of attack, China will need to develop more reliable domestic nuclear security strategies. China is also poised to become a major exporter of nuclear energy technology. China has committed to keeping nuclear technologies out of the hands of dangerous states and/or sub-state organizations, but in order to fulfill its nonproliferation obligations as well as its treaty-based commitment to share nuclear technologies, China will need to strengthen nuclear export controls and practices. This report examines and evaluates security measures at Chinese civilian nuclear power plants and suggests ways to improve them. It also reviews current export control policies and systems, identifies likely challenges to the expanding nuclear sector, and proposes possible solutions. 相似文献
408.
Adam Cobb 《African Security Review》2013,22(1):134-140
Abstract The United States Africa Command (AFRICOM) has been a military success but a strategic messaging failure. The United States’ relationships across Africa cannot be boiled down to military affairs. This paper argues that Africa has many more opportunities than challenges and thus requires a more balanced foreign policy solution from Washington DC than a new military command. For the military engagement that does need to take place, a more low-profile approach would benefit the United States in Africa. 相似文献
409.
Current International Atomic Energy Agency safeguards do not provide adequate protection against the diversion to military use of materials or technology from certain types of sensitive nuclear fuel cycle facilities. In view of highly enriched uranium's relatively greater ease of use as a nuclear explosive material than plutonium and the significant diseconomies of commercial spent fuel reprocessing, this article focuses on the need for improved international controls over uranium enrichment facilities as the proximate justification for creation of an International Nuclear Fuel Cycle Association (INFCA). In principle, the proposal is equally applicable to alleviating the proliferation concerns provoked by nuclear fuel reprocessing plants and other sensitive nuclear fuel cycle facilities. The INFCA would provide significantly increased nonproliferation assurance to its member states and the wider international community by holding long-term leasehold contracts to operate secure restricted zones containing such sensitive nuclear facilities. 相似文献
410.
ABSTRACTWhile nuclear suppliers compete in markets, they simultaneously partner in other fields. This produces a delicate relationship between civilian nuclear programs and nuclear weapon proliferation. This study explores how export competition affects suppliers’ conditions of supply related to nuclear nonproliferation. We investigated three export cases (India, North Korea, and South Korea) and identified four effects that competition has on the conditions of supply related to nonproliferation. First, under highly competitive conditions, suppliers might hesitate to enforce the conditions of supply to avoid negotiation conflicts with recipients. Second, suppliers focus on politically and economically attractive recipients while mostly ignoring unattractive ones, perhaps allowing proliferation problems to fester out of view in marginal states. Third, suppliers can build consensus on the conditions of supply to avoid being the only party experiencing negotiation conflicts. Fourth, suppliers can constrain others from relaxing the conditions of supply to maintain economic benefits and nonproliferation norms. The first two effects accelerate proliferation while the last two promote nonproliferation. Although the extent of these effects can vary with changes in nonproliferation norms, they can contribute to our understanding of the relationship between nonproliferation and civilian nuclear programs. 相似文献