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121.
CHRIS MAROLENG 《African Security Review》2013,22(3):45-48
The election of Sheik Sharif Sheik Ahmed as the transitional president of Somalia was the climax of the United Nations (UN)-led Djibouti peace process. The election, it was hoped, would herald the beginning of the reconstitution of the Somalian state. Unfortunately, nearly three years after the event, that has still not happened. The government of Sheik Sharif has faced a number of challenges which are yet to be resolved. In the end, the Djibouti peace process has not guaranteed a stable and functional national government in Somalia. 相似文献
122.
We consider an integrated usage and maintenance optimization problem for a k‐out‐of‐n system pertaining to a moving asset. The k‐out‐of‐n systems are commonly utilized in practice to increase availability, where n denotes the total number of parallel and identical units and k the number of units required to be active for a functional system. Moving assets such as aircraft, ships, and submarines are subject to different operating modes. Operating modes can dictate not only the number of system units that are needed to be active, but also where the moving asset physically is, and under which environmental conditions it operates. We use the intrinsic age concept to model the degradation process. The intrinsic age is analogous to an intrinsic clock which ticks on a different pace in different operating modes. In our problem setting, the number of active units, degradation rates of active and standby units, maintenance costs, and type of economic dependencies are functions of operating modes. In each operating mode, the decision maker should decide on the set of units to activate (usage decision) and the set of units to maintain (maintenance decision). Since the degradation rate differs for active and standby units, the units to be maintained depend on the units that have been activated, and vice versa. In order to minimize maintenance costs, usage and maintenance decisions should be jointly optimized. We formulate this problem as a Markov decision process and provide some structural properties of the optimal policy. Moreover, we assess the performance of usage policies that are commonly implemented for maritime systems. We show that the cost increase resulting from these policies is up to 27% for realistic settings. Our numerical experiments demonstrate the cases in which joint usage and maintenance optimization is more valuable. © 2017 Wiley Periodicals, Inc. Naval Research Logistics 64: 418–434, 2017 相似文献
123.
Christo Odeyemi 《Defense & Security Analysis》2015,31(4):293-302
This Critical Comment seeks to situate the United Nations Convention on the Law of the Sea (UNCLOS) within the context of South China Sea (SCS) dispute. Bearing in mind that maritime actions of the main disputants – China, Vietnam, and the Philippines – increasingly “securitise” these long-standing disputes and vice versa, the study examines the concept of a maritime “regime complex.” Whereas efforts have being made to examine UNCLOS and indeed the dispute within the framework of a maritime “regime complex,” the key finding shows that the increased “securitisation” of the disputes makes it difficult to envisage effective engagement of UNCLOS as a resolution mechanism. It will also reveal that China's firmly established expansionist agenda in the SCS region is indicative of Beijing's susceptibility to compromise a diplomatic solution to these long-standing disputes. These discoveries are structured around the knowledge that the spatial relation of the SCS critically espouses not only its geo-strategic significance in terms of natural resources endowment, but also the enduring maritime disputes within the region. 相似文献
124.
The quay crane scheduling problem consists of determining a sequence of unloading and loading movements for cranes assigned to a vessel in order to minimize the vessel completion time as well as the crane idle times. Idle times originate from interferences between cranes since these roll on the same rails and a minimum safety distance must be maintained between them. The productivity of container terminals is often measured in terms of the time necessary to load and unload vessels by quay cranes, which are the most important and expensive equipment used in ports. We formulate the quay crane scheduling problem as a vehicle routing problem with side constraints, including precedence relationships between vertices. For small size instances our formulation can be solved by CPLEX. For larger ones we have developed a branch‐and‐cut algorithm incorporating several families of valid inequalities, which exploit the precedence constraints between vertices. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2006 相似文献
125.
在载人航天器低空救生中,回收系统开伞点的初始状态参数如速度、离地面高度、弹道倾角对返回舱能否安全着陆有很大影响.与正常返回类似,低空救生中的回收系统同样经过多级伞的拉直、充气、全充满等运动过程.通过建立回收系统着陆过程的动力学模型,经过大量仿真对比分析,得到开伞点离地面高度为低空救生中返回舱安全着陆的首要因素,同时对低空救生中回收系统多级伞开伞减速过程有了详细的分析. 相似文献
126.
抢险救灾任务是国家赋予武警部队的重要使命,也是武警部队自身发展的现实需要。以加强抢险救灾装备体系能力建设的必要性、紧迫性、现实性为出发点,分析提出了需要重点发展的系列装备,并阐述了增强装备体系能力建设需把握的几个问题。 相似文献
127.
未来信息化条件下的海上战斗,信息对抗的地位越来越重要。为科学评估海上联合机动编队信息对抗能力,采取定性与定量分析相结合的方法,对编队信息对抗能力的构成及影响因素进行了分析,建立了评估指标体系,并利用指数法建立了各种能力以及综合对抗能力的评估模型。结合具体的算例给出了评估结果,并就单个评估指标对评估结果的影响进行了灵敏度分析。对海上联合机动编队信息对抗能力分析和评估,对于科学组合和正确运用信息对抗兵力,具有重要参考价值。 相似文献
128.
汤卫华 《中国人民武装警察部队学院学报》2006,22(5):26-28
在灭火救援中,尤其是在突发情况下,安全与灭火救援之间的关系值得研究。在对突发情况这一概念界定的基础上,分析了突发情况下安全与灭火救援的关系,从消防战术的角度提出了处理两者之间的关系问题,从消防技术的角度展望了两者的发展方向。 相似文献
129.
大型石油化工企业在生产、储运过程中具有较大的火灾危险性 ,而且一旦发生火灾 ,火情复杂 ,燃烧与爆炸共存 ,易出现立体、大面积、多火点燃烧和复燃、复爆现象 ,灭火难度相当大。在灭火救援中 ,必须快速集中优势兵力和装备 ,实行“两级指挥”下的统一指挥 ,坚持计划指挥与临场指挥相结合 ,发挥固定灭火装置和工程技术人员的作用 ,打好攻防组合战。 相似文献
130.
李管良 《中国人民武装警察部队学院学报》2010,(12):20-23
随着高铁技术的日益成熟和广泛运用,高铁将成为城际之间交通运输的主要途径。随着大规模的高速铁路建成运营,铁路机车车辆发生冲突、脱轨、火灾、爆炸等交通事故随时可能发生。如何科学、快速处置高速铁路交通事故,已成为消防部队面临的重要课题。结合嘉兴高速铁路建设的情况,分析了高速铁路交通事故发生的原因、特点,及高速铁路交通事故应急救援的不利因素,提出了相应处置对策。 相似文献