NUCLEAR ISLANDS

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.     

指控软件可用性工程生命周期模型

针对当前装甲指控软件的应用现状和存在的问题,运用可用性工程理论和方法,提出了指控软件的可用性工程生命周期模型,该模型包括可用性需求分析、模型构建、可用性设计、可用性测试与评估、安装部署与使用体验、用户反馈等过程。通过与一般软件测试的比较,强调可用性测试实验环境的作用。该模型突出用户的作用,重视用户反馈,可为指控软件的设计和开发提供理论指导。     

舰船空调系统不同保障模式的效费分析

分析了舰船全寿命期和使用期的结构,在此基础上,借助于WSEIAC模型,分别对舰船空调系统在两种保障方式的全寿命使用期效能和费用的各个指标进行了建模,提出了指标计算的思路与计算方法.结合海军舰船特点,在对WSEIAC效能模型进行修改和完善的基础上,给出了计算示例,结果显示了海军舰船空调系统采用岸基保障方式的合理性和优越性.     

一类具Holling-Ⅲ类功能性反应的食物有限捕食-被捕食模型的极限环

研究一类具Holling-Ⅲ类功能性反应的食物有限捕食-被捕食模型的动力学性态。应用微分方程定性理论，证明当正平衡点不稳定时该模型存在唯一稳定的极限环。     

Level workforce planning for multistage transfer lines

In this article, we define two different workforce leveling objectives for serial transfer lines. Each job is to be processed on each transfer station for c time periods (e.g., hours). We assume that the number of workers needed to complete each operation of a job in precisely c periods is given. Jobs transfer forward synchronously after every production cycle (i.e., c periods). We study two leveling objectives: maximin workforce size () and min range (R). Leveling objectives produce schedules where the cumulative number of workers needed in all stations of a transfer line does not experience dramatic changes from one production cycle to the next. For and a two‐station system, we develop a fast polynomial algorithm. The range problem is known to be NP‐complete. For the two‐station system, we develop a very fast optimal algorithm that uses a tight lower bound and an efficient procedure for finding complementary Hamiltonian cycles in bipartite graphs. Via a computational experiment, we demonstrate that range schedules are superior because not only do they limit the workforce fluctuations from one production cycle to the next, but they also do so with a minor increase in the total workforce size. We extend our results to the m‐station system and develop heuristic algorithms. We find that these heuristics work poorly for min range (R), which indicates that special structural properties of the m‐station problem need to be identified before we can develop efficient algorithms. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 577–590, 2016     

装备寿命周期备件供应网络优化方法

针对现有备件供应优化方法未从寿命周期角度考虑备件供应优化问题,将寿命周期不同阶段的备件需求特征融入备件供应网络设计中,实施动态需求特征下的寿命周期整体优化。深入分析寿命周期不同阶段的备件需求特征;建立备件供应响应时间转移方程,在此基础上,构建使寿命周期备件保障效益最大的多目标混合整数规划模型。通过仿真案例证明了多种备件保障模式的组合能够显著提高寿命周期保障效益,寿命周期整体优化可以实施更高效的备件供应。     

Mitigation of EDFA transient effects in variable duty cycle pulsed signals

We report the transient effects in Erbium Doped Fiber Amplifier (EDFA) systems for pulsed signals with different duty-cycles. The work includes the analysis using three different duty-cycles, 10%, 20% and 50%. A curve fitting technique is also proposed to predict the transients of any lesser duty-cycled pulse, once the transients of a larger duty-cycled pulse is known. Mathematical evaluation confirms the double exponential shape of transient distorted signal. Further, EDFA transient effect is experimentally verified on a Wavelength Division Multiplexed (WDM) link by multiplexing high and low bitrate modulated optical signals. We conclude the paper by proposing a transient suppression technique for variable duty-cycle signals and analyzing its effectiveness with different wavelength spacing.     

Maintenance scheduling for modular systems: Modeling and algorithms

We study new models of scheduled maintenance management for modular systems, consisting of multiple components with respective cycle limits. The cycle limit of each component specifies the time interval in which this component must be repaired or replaced. The goal is to compute a feasible maintenance schedule that minimizes the cost associated with component maintenance. Applications of these models arise in Air Force aircraft maintenance as well as in other arenas with required preventive maintenance. The typical cost structures that arise in practical settings are submodular, which make the resulting models computationally challenging. We develop two efficient and operationally tenable approximation algorithms. We prove constant factor worst‐case guarantees for both algorithms, and present computational experiments showing that these algorithms perform within a few percent of optimality on operationally relevant instances. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 472–488, 2014     

化学键合胶凝材料抗硫酸盐侵蚀性能

采用浸-烘循环的方法模拟干湿循环交替环境进行新型化学键合胶凝材料抗硫酸盐加速侵蚀试验.侵蚀溶液为质量浓度为5％的硫酸钠溶液,一组试验采用全浸-烘循环,另一组试验采用半浸-烘循环.在经受30×N(N=1,2,3,4,5)次循环后,测定试件的强度耐蚀系数和质量损失率,以此评价化学键合胶凝材料抗硫酸盐侵蚀性能.试验结果表明:半浸-烘循环的侵蚀比全浸-烘循环的侵蚀严重;在经受150次侵蚀循环后,试件外观无严重破损,质量不减反增,强度也不降低,说明化学键合胶凝材料具有优良的抗硫酸盐侵蚀性能.     

THE NUCLEAR THRESHOLD STATES

“Nuclear threshold states”—those that have chosen nuclear restraint despite having significant nuclear capabilities—seem like the perfect partners for the reinvigorated drive toward global nuclear disarmament. Having chosen nuclear restraint, threshold states may embrace disarmament as a way to guarantee the viability of their choice (which may be impossible in a proliferating world). Supporting disarmament efforts affirms their restraint, both self-congratulating and self-fulfilling. Additionally, the commitment to their non-nuclear status springs at least in part from a moral stance against nuclear weapons that lends itself to energetic support of global disarmament. However, threshold states also offer significant challenges to the movement for nuclear weapons elimination, in particular in relation to acquisition of enrichment and reprocessing facilities. This article analyzes both the challenges and opportunities posed by threshold states by examining the cases of Brazil and Japan.