On allocating one active redundancy to coherent systems with dependent and heterogeneous components' lifetimes

This article studies coherent systems of heterogenous and statistically dependent components' lifetimes. We present a sufficient and necessary condition for a stochastically longer system lifetime resulted by allocating a single active redundancy. For exchangeable components' lifetimes, allocating the redundancy to the component with more minimal path sets is proved to produce a more reliable system, and for systems with stochastic arrangement increasing components' lifetimes and symmetric structure with respect to two components, allocating the redundancy to the weaker one brings forth a larger reliability. Several numerical examples are presented to illustrate the theoretical results as well. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 335–345, 2016     

China’s Search for a ‘Strategic Air Force’

Once dismissed by many outside observers, the Chinese People’s Liberation Army Air Force (PLAAF) has undergone an impressive transformation over the past two decades, emerging as one of the world’s premier air forces. As it continues to modernize, it is focused on becoming a ‘strategic air force.’ PLAAF strategists suggest this means it should play a decisive role in protecting Chinese national interests, field modern capabilities commensurate with China’s standing as a major power, and enjoy the institutional status befitting its role as a ‘strategic service,’ an important consideration given the historical dominance of the ground force in China’s military.     

Stochastic regret minimization for revenue management problems with nonstationary demands

We study an admission control model in revenue management with nonstationary and correlated demands over a finite discrete time horizon. The arrival probabilities are updated by current available information, that is, past customer arrivals and some other exogenous information. We develop a regret‐based framework, which measures the difference in revenue between a clairvoyant optimal policy that has access to all realizations of randomness a priori and a given feasible policy which does not have access to this future information. This regret minimization framework better spells out the trade‐offs of each accept/reject decision. We proceed using the lens of approximation algorithms to devise a conceptually simple regret‐parity policy. We show the proposed policy achieves 2‐approximation of the optimal policy in terms of total regret for a two‐class problem, and then extend our results to a multiclass problem with a fairness constraint. Our goal in this article is to make progress toward understanding the marriage between stochastic regret minimization and approximation algorithms in the realm of revenue management and dynamic resource allocation. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 433–448, 2016     

Moving Beyond Population-Centric vs. Enemy-Centric Counterinsurgency

Historically, insurgency is one of the most prevalent forms of armed conflict and it is likely to remain common in the foreseeable future. Recent experiences with counterinsurgency in Iraq and Afghanistan offer many lessons for future counterinsurgents, but the discourse on the subject continues to be mired in a traditional dichotomy pitting population-centric approaches to counterinsurgency against enemy-centric approaches. Historical analysis suggests that this traditional dichotomy is not a sufficiently nuanced way to understand or plan for such operations. Instead, discussions of counterinsurgency should focus on two dimensions: actions (use of physical force vs. political or moral actions) and targets (active insurgents vs. insurgent support). This perspective divides the space of possible counterinsurgency efforts into four quadrants, suggesting that effective counterinsurgency campaigns find a balance of effort across the four quadrants that is well matched to the specific context.     

面向多平台多目标协同跟踪的指派问题

针对多平台多目标协同跟踪中要求多个无人地面平台尽可能均匀地协同跟踪多个目标的特点,提出了改进的离散粒子群优化算法。首先采用连续型粒子群优化算法中的速度和位置迭代公式,然后对粒子位置进行离散编码,使粒子编码对应于可行的指派方案;其次,在优化算法中引入局部搜索,提高算法寻优性能。最后将所提算法应用于多平台多目标协同跟踪中的指派问题,并与未加入局部搜索的粒子群优化算法比较,仿真结果表明,加入局部搜索后的离散粒子群优化算法具有较好的寻优性能。     

相控阵雷达LPI搜索方法研究

相控阵雷达可通过合理配置工作参数优化其性能。针对相控阵雷达在搜索目标时易受敌方电子侦察设备威胁的现实,研究了在保持搜索能力的同时,通过合理配置参数降低截获概率的问题。分析了影响相控阵雷达搜索状态LPI(Low Probability of Intercept)性能的主要因素,建立了截获概率模型与搜索能力模型,给出了3种参数调整策略。仿真试验验证了模型的有效性,并比较了3种策略的优劣。     

Implementing the Global Strategy where it matters most: the EU’s credibility deficit and the European neighbourhood

The EU Global Strategy (EUGS) is a broad and ambitious document in terms of its geographic scope and thematic priorities. However, the EU cannot devote equal attention to all aspects of the EUGS; so there is still scope for more clarity regarding the EU’s core strategic aims. This article argues that in addition to fostering internal cohesion, the EU’s strategic priority must involve stabilizing its own neighbourhood. This task has challenged the EU for decades because of an inherent credibility deficit regarding the EU’s own capabilities, yet the EUGS does not diagnose and remedy this problem as effectively as it could have. Therefore much more work will need to be done in terms of reforming EU institutions and developing common capabilities if the EU hopes to achieve its central internal and external security goals as outlined in the EUGS and related policy statements.     

Introduction: one-and-a-half cheers for the EU Global Strategy

EU High Representative Federica Mogherini presented her EU Global Strategy (EUGS) in June 2016. Encircled by security crises, it is difficult to think of something more important for Europe than collective action with the aim of weathering the storm. The EUGS, in this respect, seeks to define common ends and identify means. So what do we make of the EUGS? What does the EUGS tell us about the current role of the EU in global affairs? And how will the withdrawal of the UK from the EU affect foreign and security policy? As a way of introduction to the forum, this article notes that the EUGS focuses on the neighbourhood, puts the interests of European citizens first, identifies civilian means, and has created momentum on security policy. The key question, however, remains whether there is any interest in the EUGS beyond the foreign policy elites.     

采用可达域覆盖的多航天器协同护卫策略

针对高轨高价值目标护卫问题,提出了一种基于可达域覆盖的多航天器协同护卫策略。从相对运动视角对协同护卫任务进行了描述,并将威胁源多脉冲机动可达域问题建模为凸优化问题求解。在滚动优化框架下,根据动态更新的威胁源终端可达域,设计协同护卫平面及护卫点,以此为终端位置约束构建多航天器协同轨迹规划模型,生成相应护卫轨迹。仿真结果表明,所提出的可达域分析方法能够快速计算威胁源终端可达域,协同护卫策略在多个场景下均能有效阻止威胁源,且护卫成功率随护卫航天器机动能力增强而增大。     

Damage functions and estimates of fratricide and collateral damage

There are multiple damage functions in the literature to estimate the probability that a single weapon detonation destroys a point target. This paper addresses differences in the tails of four of the more popular damage functions. These four cover the asymptotic tail behaviors of all monotonically decreasing damage functions with well‐behaved hazard functions. The differences in estimates of probability of kill are quite dramatic for large aim‐point offsets. This is particularly important when balancing the number of threats that can be engaged with the chances of fratricide and collateral damage. In general, analysts substituting one damage function for another may badly estimate kill probabilities in offset‐aiming, which could result in poor doctrine. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 306–321, 2003.