基于输出饱和条件下磁浮列车悬浮控制参数优化

低速磁浮列车利用电磁吸力支撑车体,相比轮轨列车具有噪音小、转弯半径小、爬坡能力强等优点。研究控制器输出饱和条件下悬浮系统的稳定性问题,可以避免由于电网电压约束而可能出现的失稳现象,提高了系统运行的可靠性。基于磁浮列车单点悬浮模型,使用电流-位置双环设计方法设计得到可稳定悬浮的控制算法。由于磁浮列车悬浮控制器的输出饱和环节,进一步提出了一种基于搜索极大椭球的控制参数优化方法,在不改变控制算法设计的前提下实现了参数优化。通过仿真和试验均验证了优化后的控制效果,有效指导了实际系统的工程调试。     

Enhancing Political Cohesion in NATO during the 1950s or: How it Learned to Stop Worrying and Love the (Tactical) Bomb

This article argues that the perceived need by NATO to nurture political cohesion within the Alliance during the 1950s resulted in the adoption of strategic concepts that were out-of-step with the military environment in which it was operating. It maintains that the Alliance acquiesced to American leadership on nuclear issues which led to the development of tactical nuclear capabilities at the expense of conventional war-fighting capabilities for the defence of the European Central Front. This resulted in a strategic concept that enhanced political cohesion but was militarily unviable.     

Flexible capacity strategy in an asymmetric oligopoly market with competition and demand uncertainty

This article studies flexible capacity strategy (FCS) under oligopoly competition with uncertain demand. Each firm utilizes either the FCS or inflexible capacity strategy (IFCS). Flexible firms can postpone their productions until observing the actual demand, whereas inflexible firms cannot. We formulate a new asymmetrical oligopoly model for the problem, and obtain capacity and production decisions of the firms at Nash equilibrium. It is interesting to verify that cross‐group competition determines the capacity allocation between the two groups of firms, while intergroup competition determines the market share within each group. Moreover, we show that the two strategies coexist among firms only when cost differentiation is medium. Counterintuitively, flexible firms benefit from increasing production cost when the inflexible competition intensity is sufficiently high. This is because of retreat of inflexible firms, flexibility effect, and the corresponding high price. We identify conditions under which FCS is superior than IFCS. We also demonstrate that flexible firms benefit from increasing demand uncertainty. However, when demand variance is not very large, flexible firms may be disadvantaged. We further investigate the effects of cross‐group and intergroup competition on individual performance of the firms. We show that as flexible competition intensity increases, inflexible firms are mainly affected by the cross‐group competition first and then by the intergroup competition, whereas flexible firms are mainly affected by the intergroup competition. Finally, we examine endogenous flexibility and identify its three drivers: cost parameters, cross‐group competition, and intergroup competition. © 2017 Wiley Periodicals, Inc. Naval Research Logistics 64: 117–138, 2017     

Global strategic studies: a manifesto

This contribution reflects on the state of strategic studies today and the criticism it has received in recent years, as being outdated and irrelevant. The authors formulate some premises for reinvigorating this field of inquiry by widening its scope and research agenda to do more justice to the wide variety of actors, perspectives and practices observable in the enterprise of strategy in our contemporary globalised world.     

分布式计算环境下的栅格数据存储策略

针对传统的栅格数据存储策略不能满足分布式计算环境下粗粒度数据访问需求,应对海量栅格数据计算时效率低下的问题,结合分布式文件系统的存储特点,同时考虑地图代数算子在Map/Reduce阶段以栅格瓦片为单位的计算特点,提出一种基于Hadoop分布式文件系统的栅格瓦片存储策略。围绕栅格数据瓦片分割、压缩瓦片数据组织与存储、分布式文件输入输出接口改进等方面对该存储策略加以实现,并使用基于该存储策略的地图代数局部算子的分布式计算流程加以验证。理论分析与实验结果表明,该策略能够显著提高分布式计算环境下空间分析算子的运算速度。     

基于Pareto排序法的战时装备维修任务多目标调度方法

针对战时武器装备维修保障问题,建立了包括最大完工时间、延迟时间和维修单元负荷在内的多目标优化调度模型。为提高解的多样性和收敛性,构建了一种基于Pareto排序法和小生境技术相结合的遗传算法用于模型求解,引入Pareto排序和拥挤距离进行适应度计算,通过混沌系统随机生成权重系数,并使用小生境技术改进选择方式。通过实例验证表明,该方法能够有效地解决装备维修多目标调度问题。     

美军无人机集群项目发展

近几年来,无人机集群技术在美军多个方面的推动下,引起了全世界的热切关注。文章简要总结了美军无人机集群发展现状,梳理了美军开展无人机集群技术的初衷,并分析认为美军数量型无人机集群发展战略不完全适用于现阶段我军军情。文中给出了我国现阶段发展无人机集群的思路,这对全面认识无人机集群的优势、明晰我军无人机集群技术发展方向具有一定的参考价值。     

增强军校本科学员指挥谋略能力研究——基于计算机兵棋系统

对指挥谋略进行概念分析,确定基于计算机兵棋系统的指挥谋略训练内容;明确计算机兵棋推演的一般步骤和注意事项;以联军2004年11月"破晓"行动为例运用计算机兵棋系统进行指挥谋略训练。研究表明,基于计算机兵棋系统运用战例研究可以成为增强军校本科学员指挥谋略的训练模式。     

美军采办项目的采办策略分析

采办策略是美军针对具体采办项目强制规定的覆盖整个项目寿命周期的纲领性文件,对于保障在资源限制条件下达成项目采办目标具有重要的意义。本文首先分析了采办策略的概念,随后研究了采办策略的主要内容、与采办管理周期的匹配要求,最后提出了对我军装备采办改革的启示。     

“Made in China”: an emerging brand in the global arms market

Possession of a brand is a sine qua non for economic success, not least because it connotes trust in delivering the value promised. Although Western arms exporters offer branded systems whose sales are influenced by price, there is a plethora of other economic variables, such as offset requirements and life-cycle support. Entrants to the international arms market will struggle without such arms “packages.” China’s entry, however, goes beyond the traditional economic paradigm. A four-stage historical model offers the backdrop for identifying the drivers that have forged its market entry into 55 countries worldwide. The strategy initially focused on sales of rudimentary military equipment for political purposes, but recently it has begun to commercialize exports, repositioning them from a low- to a high-tech sales trajectory. A Sino “brand” is thus emerging, reflecting both competitiveness and diplomatic considerations, especially non-interference in client state domestic affairs.