履带式车辆半主动悬架的模糊神经网络控制

在1/2车体振动模型的基础上,引入了模糊神经网络控制器,模糊控制用来对付系统的非线性,神经网络用来辨识路面的变化情况,实时调节模糊控制器的量化因子,使模糊控制器对路面的变化具有自适应能力。仿真和台架实验结果表明,模糊控制器能有效地控制半主动悬架系统,半主动悬架在减少振动,提高乘坐舒适性方面优于传统的被动悬架。     

吸气式高超声速飞行器助推分离过程数值仿真

针对吸气式高超声速冲压发动机验证性试验特殊的飞行环境和助推分离条件,以某轴对称吸气式高超声速飞行器级间分离问题为具体研究对象,采用非结构网格局部网格重构技术和非定常问题非定常六自由度问题仿真方法,对该复杂构型飞行器助推分离过程进行数值计算。研究得到弱干扰冷态分离状态下飞行器及助推器的运动参数和气动力参数在分离过程中的发展规律。对0.3 s内助推器的位移轨迹进行分析,判断分离方案的可行性,并给出最佳的分离工况条件。     

履带车辆转向功率与直驶功率对比分析

履带车辆转向与轮式车辆转向有着本质的区别.履带车辆转向时的功率消耗较直线行驶功率消耗要大的多.提出了转向功率比的概念,建立了考虑高速履带滑转、低速履带滑移条件下履带车辆转向功率比的计算模型.通过对模型简化与推导,得到考虑履带滑转、滑移实际条件的模型与不考虑履带滑转、滑移理论模型的等价关系.对安装不同转向机构履带车辆的转向功率比进行了分析.通过在3种典型地面条件下对现有的具有有限个规定转向半径车型的示例计算,得到履带车辆转向功率消耗为直线行驶功率消耗的1.63～3.24倍的结论.     

飞行器多学科设计优化理论的工程应用

目前,飞行器的多学科设计优化(MDO)方法研究已经成为国际上航天领域的一个研究热点,但在我国,与MDO基础理论研究的迅速发展相比,MDO的工程应用研究相对滞后,甚至导致部分飞行器设计人员对于MDO理论的实用性产生质疑.本文结合我们近十多年来的研究工作,在分析MDO工程应用所面临困难的基础上,总结了MDO工程应用研究的关...     

Drone Strikes and Grand Strategy: Toward a Political Understanding of the Uses of Unmanned Aerial Vehicle Attacks in US Security Policy

This article analyzes the political utility of US drone strikes theoretically and deductively. Placing strikes within the context of the theorized political functions of force and considering how they fit into two grand strategies, restraint and selective engagement, I argue that these strikes buy the United States relatively little in the way of political effects assuring its own security because the terrorism threat they are intended to combat is a limited one within the skein of US global interests. Furthermore, their contribution to counter-terrorism efforts is likely to diminish with the adoption of armed drones by non-state actors. Drone strikes can, however, provide leverage over recalcitrant US client states while reassuring liberal partners and giving them some leverage over US choices. In addition, within the counter-terrorism sphere, drone strikes are less likely to inflame popular opinion than are alternative uses of force. This analysis contributes to an increasingly rigorous examination of the strikes’ role in US foreign and security policy.     

无约束自由体有限元分析中的准静态法

在对某水下无约束航行体进行有限元静力分析的时候,由于无法限定结构的自由度而使刚度矩阵奇异,从而导致求解失败。为了解决这一问题,采用强迫约束法和准静态法(惯性释放)对此航行体进行了有限元静力对比计算,结果表明:用强迫约束法对水下航行体进行静力分析时,在施加强迫约束的部位出现了严重的应力集中现象,应力最大值为1.25×106Pa,应力集中使得整个结构的应力分布与实验数据相差较大,可认为计算结果错误;采用惯性释放法对其进行静力分析时,应力最大值为3.27×105Pa,整个结构的应力分布合理,与实验数据一致,计算结果正确。     

履带车辆悬挂系统振动仿真与减振器能耗分析

为研究履带车辆传统减振器的能耗与路况、车速的关系,应用动力学仿真软件RecurDyn建立了突出悬挂系统的履带车辆模型。依据国际标准,用不同等级的随机路面表示不同路况,并改变模型中的主动轮驱动转速,得到不同车速。仿真与分析结果表明:同一路况下,车速对减振器能耗的影响不大;同一车速下,路况越恶劣,减振器能耗显著增大。研究结果对履带车辆馈能悬挂的研究具有一定的指导意义。     

低慢小无人机对军事区域的安全威胁及其应对方法

低慢小无人机具有小型化、红外与雷达暴露征候小、飞行高度低、飞行轨迹不定以及购买使用几乎无门槛等特征,给当前全球军事区域和军事行动安全带来了新的挑战。本文首先分析了世界主要国家对低慢小无人机的界定、国内外管控情况和相关威胁事件;然后,从低慢小无人机的侦察袭击能力、军事区域现有安防措施和低慢小无人机对军事区域进行侦察的相关案例入手,讨论了低慢小无人机对军事区域的侦察袭击的威胁;最后从政策制度、营区部署与隐蔽伪装以及反制措施配置三方面对军事区域防低慢小无人机侦察袭击的手段与措施进行了分析和研究,重点就机动性、经济性、技术难度、可操作性、反应速度、打击效果、能否对抗集群目标以及适用场合等方面对当前各种反无人机的干扰、驱离、毁坏措施进行了对比。     

俄军装甲车辆动力装置的综合效能评估

为了对装甲车辆的动力装置进行有效地评价,采用反映其战术技术效能水平的评价指标,应用加权平均的评价方法对俄军典型装甲车辆的动力装置进行了综合评估,其评价指标及评价方法对未来我军装甲车辆的论证具有指导意义.     

Western drones and African security

While unmanned aerial vehicles (UAVs) have become a standard element of modern armed forces, African countries have been reluctant to acquire remotely piloted aircraft for military purposes until recently. This is mainly due to a lack of industrial capabilities and, for military purposes so far, procurement policies that have concentrated on small arms and light weapons, more prestigious armoured vehicles and combat aircraft. Moreover, counter-insurgency strategies in Africa tend to focus on manoeuvre warfare, co-opting rebels or fighting them using armed proxies. As a consequence, international counterterrorism operations against fanatical and reckless groups like al-Qaeda in the Islamic Maghreb and Boko Haram in sub-Saharan Africa are characterised by a strong dependence on Western forces providing UAV-based reconnaissance and, in some cases for the United States, military strikes by drones. This essay reviews some of the incentives and problems of the use of UAVs in the African context. Given the geographical and military conditions of asymmetric warfare in Africa, and potential problems concerning international law, ethical aspects of the use of arms, and civil–military relations notwithstanding, it is argued that African security forces should develop their own UAV capabilities by intensifying their cooperation with Western armed forces.