高超声速滑翔导弹气动参数自适应跟踪建模

针对高超声速滑翔导弹跟踪中状态模型构建问题,研究基于制导变量变化规律的气动参数建模方法。对气动参数进行分析,指出传统建模方法的缺点。在假设制导变量服从一阶时滞过程的前提下,利用线性化的气动系数推导气动参数模型,通过分析不同飞行状态下的模型变式,证明模型对目标机动具有自适应性。对模型中未知参数的取值问题进行讨论,实现模型与飞行状态的自适应匹配。仿真结果表明：当目标发生机动时,所提模型性能明显优于传统模型。同时,在不同滤波器参数条件下的仿真结果进一步证实了模型的有效性。     

基于改进能量检测的航空集群网络干扰感知

为了增强复杂电磁环境中航空集群战术网络的抗干扰能力,提出把同时收发认知抗干扰电台应用于航空集群网络节点,且每个节点采用改进能量检测方法进行干扰感知。在此基础上,分别研究了存在单/多个干扰源时的网络节点干扰感知性能,推导出干扰感知的虚警概率和检测概率的闭式表达。仿真结果表明,通过调节改进能量检测器的参数p,可以提高航空集群机载战术网络的干扰感知能力。     

The Organization of the Defense Support System: An Economic Geography Perspective

In the context of restricted budgetary resources and the growing cost of maintenance, repair, and overhaul (MRO) activities, a major issue for modern armed forces is to sustain defense platforms. A possible method consists of realizing economies of scale through the concentration of maintenance activities, which involves the spatial reorganization of existing industrial sites dedicated to MRO. This article provides a formalized framework to discuss the optimal organization for the MRO of defense platforms in space. The public planner organizes the maintenance of defense platforms with only two possible spatial configurations. In the dispersed configuration, two industrial production units in charge of the maintenance optimally cover space, whereas in the concentrated configuration, a unique industrial unit covers space. Focusing on the tipping point between the two configurations, the balance of forces between agglomeration and dispersion in defense support activities is described and discussed. On the one hand, economies of scale provide an opportunity to optimize defense support costs, favoring concentration in a unique industrial unit. On the other hand, space causes dispersion to reduce both transport costs and operational social costs. This trade-off illustrates a general principle in spatial economics with an application to MRO production in the French case.     

Geopolitical Risks and Movements in Islamic Bond and Equity Markets: A Note

This study applies a non-parametric causality-in-quantiles test to examine the causal effect of geopolitical risks on return and volatility dynamics of Islamic equity and bond markets. Geopolitical risks are generally found to impact Islamic equity market volatility measures, rather than returns. However, geopolitical risks tend to predict both returns and volatility measures of Islamic bonds. Interestingly, causality, when it exists for returns and/or volatility of Islamic equities and bonds, is found to hold over entire conditional distributions of returns and volatilities, barring the extreme ends of the same.     

Humanitarians at sea: Selective emulation across migrant rescue NGOs in the Mediterranean sea

Between 2014 and 2017, no less than 10 different non-governmental organizations (NGOs) conducted maritime Search and Rescue (SAR) operations off the coast of Libya. By rescuing over 100,000 migrants in three years, these NGOs became the largest provider of SAR in the Mediterranean. The theory of institutionalism suggests that organizations conducting similar activities are likely to converge in a process of mimetic isomorphism, deliberately imitating one another to increase their effectiveness and cope with uncertainty. These 10 SAR NGOs, however, developed two different rescue models: While some rescued migrants and disembarked them in Italian ports, others only simply assisted those in distress until the arrival of another ship transporting them to land. They also cooperated with Italian and European authorities to different degrees. Why did SAR NGOs imitated many elements of existing non-governmental rescue models, but discarded some others? This article argues that differences in material capabilities and organizational role conceptions are crucial to explain why newer SAR NGOs have imitated most but not all of their predecessors’ policies, engaging in a process of “selective emulation.”     

Robust shortest path planning and semicontractive dynamic programming

In this article, we consider shortest path problems in a directed graph where the transitions between nodes are subject to uncertainty. We use a minimax formulation, where the objective is to guarantee that a special destination state is reached with a minimum cost path under the worst possible instance of the uncertainty. Problems of this type arise, among others, in planning and pursuit‐evasion contexts, and in model predictive control. Our analysis makes use of the recently developed theory of abstract semicontractive dynamic programming models. We investigate questions of existence and uniqueness of solution of the optimality equation, existence of optimal paths, and the validity of various algorithms patterned after the classical methods of value and policy iteration, as well as a Dijkstra‐like algorithm for problems with nonnegative arc lengths.© 2016 Wiley Periodicals, Inc. Naval Research Logistics 66:15–37, 2019     

电磁轨道发射中内弹道动力响应特性分析

将轨道简化为移动载荷作用下固定在弹性支撑上的Bernoulli-Euler梁,通过静态电磁-结构耦合有限元模型求得外围封装的等效刚度,计算得到发射器的临界速度。另外,利用混合有限元/边界元法建立电磁-结构-运动多物理场耦合的动力学模型,求得枢轨动态接触压力和轨道的应力应变分布特性。通过在轨道背面布置光纤光栅应变传感器,利用测量数据验证了动力响应特性,并分析了弹丸在内弹道的稳定性。针对典型30 mm × 30 mm矩形口径发射器,分析及试验结果表明：C型电枢对轨道的电磁挤压力在平顶沿起始时刻达到最大值,之后随着时间推移逐渐减小;电枢通过引起的应力波在高速段容易与轨道中反射应力波发生共振,并且轨道在电枢运动的中间高速段区域受力最为集中,应力集中水平约是起始低速段区域的2.44倍;电枢运动高速段会出现晃动现象,进而引起上下轨道受力的不对称性。分析及试验结果对研究电磁轨道发射器内弹道动力响应特性和发射器结构设计具有重要指导意义。     

新体制导航信号下I/Q幅相不一致对接收机测距零值的影响分析

随着现代化导航信号带宽的增大,由于可以大幅降低采样率,复信号采样的优势日趋明显。由于存在I/Q幅相误差,复信号采样对导航接收机伪距测量造成了一定影响。改进了信道非理想与I/Q幅相误差共同影响BPSK/QPSK信号零值测量的分析模型;在该模型基础上,推导得到了任意I/Q误差和信道非理想特性影响BOC信号伪距零值的模型;探讨了二者在频域抗干扰应用场景下引起的零值变化;理论分析与软件接收机仿真结果高度吻合,误差在1.5×10^-4码片内,证明了分析模型的精确性。该分析方法可用于对高性能导航接收机信道特性进行事先约束及筛选,以确保干扰场景下的零值变化满足要求。     

驱护舰编队对海攻击火力运用

针对驱护舰武器装备的发展,结合现代海上进攻战斗的新特点,对驱护舰编队对海攻击时的阶段划分、火力运用等问题进行了分析,提出了驱护舰编队对海攻击火力分配的原则和火力运用方式,并就确保编队的火力运用提出了引导保障、电磁保障应遵循的战术原则,对部队作战与训练具有一定的参考应用价值。     

地地导弹突击目标火力分配模型

火力分配及分配的优化是地地导弹作战行动中需要解决的重要问题。通过具体分析,建立了地地导弹突击目标火力分配的数学模型,并主动运用动态规划的思想分析了地地导弹突击目标火力分配的选优过程,提出了对模型的优化解法。进而,对解法进行了计算机语言的实现。经过程序计算,快速、准确地得出了所给实例的优化分配方案。