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     

指挥控制结构的抗毁性分析研究

指挥控制结构的抗毁性决定了战时指挥控制体系在遭受敌打击时,其减缓受到的损害和恢复其相关能力的能力,在未来信息化作战条件下具有重要的现实意义。为了明确指挥控制结构的抗毁性与攻击方式等因素的关系,在指控复杂网络模型的基础上,对抗毁性的描述参数进行了定义,以仿真实验的方式对比了随机攻击与重点攻击、考虑时间因素的攻击、按照不同标准(度和介数)排序进行的攻击等。从而揭示了信息化作战环境下指挥控制结构抗毁性的表现与维护重点。     

气态煤油超声速燃烧简化化学反应模型

为探究超燃冲压发动机燃烧室中煤油燃料燃烧的化学动力学过程,综合采用敏感性分析方法与路径分析方法,针对RP-3航空煤油三组分替代燃料的详细反应模型进行简化,建立一种适用于超声速燃烧流场数值模拟的新型26组分89反应简化燃烧反应模型。采用该简化燃烧模型对RP-3航空煤油替代燃料的点火、燃烧特性进行数值模拟,并与详细反应模型结果和试验数据进行对比校验。此外,将该简化燃烧模型与超声速燃烧流场计算方法相结合,数值分析了典型超燃冲压发动机燃烧室流场内化学动力学特性。研究结果表明：新型简化燃烧反应模型在不影响数值模拟精度的前提下,有效减少了反应组分与反应方程个数,提高了超声速复杂燃烧流场的数值模拟效率,并且能够准确获得烯烃、炔烃等重要中间燃烧产物以及小分子活性基团的空间分布规律,给出更全面的流场信息。     

A three-stage model for the perforation of finite metallic plates by long rods at high velocities

A three-stage theoretical model is presented herein to predict the perforation of a thick metallic plate struck normally by a long rod at high velocities. The model is suggested on the basis of the assumption that the perforation of a thick metallic plate by a long rod can be divided into three stages: (1) initial penetration; (2) plug formation and (3) plug slipping and separation. Various analytical equations are derived which can be employed to predict the ballistic limit, residual velocity and residual length of the long rod. It is demonstrated that the present model predictions are in good agreement with available experimental results for the perforation of finite steel targets struck normally by steel as well as tungsten alloy long rods at high velocities. It is also demonstrated that the dynamic maximum shear stress of a plate material has strong effect on plug formation and plug thickness which, in turn, exerts considerable influence on the residual velocities and lengths of a long rod at impact velocities just above the ballistic limit.     

The Trump effect downunder: U.S. allies,Australian strategic culture,and the politics of path dependence

Donald Trump’s election precipitated a debate in Australia about the value of retaining close alliance ties with the United States. Similar dynamics are discernible in other U.S. allies as the negative impact of Trump administration policies becomes clearer. Yet despite this “Trump effect,” we argue Australia is unlikely to distance itself from the United States because at the core of Australia’s strategic culture is a very positive “cultural orientation” toward the United States that is highly institutionalized in treaties, formal bilateral ties, Track 2 diplomacy, and public opinion. Such institutionalized ties have powerful path dependent effects. Accordingly, we conclude that the Trump effect does not constitute a powerful enough “exogenous shock” to move Australia off its well-worn grand-strategic path. But this alliance relationship is marked by both high cultural affinity and high institutionalization: American policy-makers should seriously consider whether other U.S. allies can tolerate similar levels of “stress.”     

一种地对空攻击武器的追及与跟踪方法

针对一种地对空武器在接到雷达跟踪指令时,由战斗准备状态追及目标、跟踪目标,直至跟踪射程区域外,或由雷达重新下达指令进入战斗准备状态的轨迹规划方法.轨迹规划中不仅考虑了系统最大速度的限制,同时还考虑了武器系统抗最大加速度的指标要求,在约束条件下规划追及过程,实现最优规划的计算方法.主要介绍了模糊追及和跟踪的计算规划方法,具有一定的实际意义.     

无人机电子干扰条件下的路径规划

针对机载预警雷达结合地面雷达对低空突防无人机构成的严重威胁,提出一种基于A*算法的路径规划算法.该算法分析了电子干扰和无人机RCS对雷达探测空间的影响,建立了新的雷达探测空间模型和威胁模型进行路径规划,将A*算法应用于无人机的路径规划过程.在此基础上给出了应用该方法的具体步骤,并进行了MATLAB仿真.仿真结果表明:考虑电子干扰对雷达威胁区域影响的情况下规划的飞行路径飞行器能有效回避威胁,有效提高无人机的低空突防能力.     

均匀设计法在建立PELE爆裂效应关系模型中的应用

为了研究钢壳体PELE爆裂效应与影响因素之间的数学关系,对钢壳体PELE侵彻钢板进行了数值仿真和试验。采用均匀设计法设计仿真工况,将仿真结果进行回归分析,得出爆裂效应与影响因素之间的数学关系式,实弹侵彻实验结果与仿真结果基本吻合。研究表明,影响因素均与壳体爆裂长度成非线性关系,增大靶板厚度、弹芯长度和着速或减小壳体厚度均有利于提高钢壳体的爆裂效应。相关结论为PELE的工程设计和应用提供了理论基础。     

基于湍流冲击振动的输油管道稳定性研究

要水流冲刷管底形成悬空管道,悬空管道假设为一端固定一端铰支的均质等截面简支梁。在分析管道垂直载荷对悬空管道临界长度影响的基础上,考虑到输油管道振动引起的动应力以及管道振动时的外部阻尼、管道轴向力和内压对管道的作用,对悬空管道进行受力分析,导出管道振动微分方程。以保证管道强度的安全可靠为判据,计算求出悬空管道的临界长度,以便预测管道失稳条件,并对其及时采取稳固及抢修措施。     

巡航导弹攻击路径组的优化与评估

为保证对敌方目标实施多次有效攻击,巡航导弹攻击路径选择的关键在于寻找一组优化路径而不是一条优化路径(如果存在),既满足性能指标要求,又满足作战应用要求.在作战区域内任意两个匹配区之间飞行航迹已知(专题讨论)的情况下,就巡航导弹攻击路径组的优化与评估问题进行了探讨,分析了导弹作战运用要求和性能指标要求,建立了攻击路径组的优化与评估模型,计算结果表明:所给出优化与评估模型是可行的,能够满足巡航导弹实际作战要求.