Dynamic analysis of a guided projectile during engraving process

The reliability of the electronic components inside a guided projectile is highly affected by the launch dynamics of guided projectile. The engraving process plays a crucial role on determining the ballistic performance and projectile stability. This paper analyzes the dynamic response of a guided projectile during the engraving process. By considering the projectile center of gravity moving during the engraving process, a dynamics model is established with the coupling of interior ballistic equations. The results detail the stress situation of a guided projectile band during its engraving process. Meanwhile, the axial dynamic response of projectile in the several milliseconds following the engraving process is also researched. To further explore how the different performance of the engraving band can affect the dynamics of guided projectile, this paper focuses on these two aspects: (a) the effects caused by the different band geometry; and (b) the effects caused by different band materials. The time domain and frequency domain responses show that the dynamics of the projectile are quite sensitive to the engraving band width. A material with a small modulus of elasticity is more stable than one with a high modulus of elasticity.     

Effect of welding processes and consumables on fatigue crack growth behaviour of armour grade quenched and tempered steel joints

Quenched and Tempered (Q&T) steels are widely used in the construction of military vehicles due to its high strength to weight ratio and high hardness. These steels are prone to hydrogen induced cracking (HIC) in the heat affected zone (HAZ) after welding. The use of austenitic stainless steel (ASS) consumables to weld the above steel was the only available remedy because of higher solubility for hydrogen in austenitic phase. The use of stainless steel consumables for a non-stainless steel base metal is not economical. Hence, alternate consumables for welding Q&T steels and their vulnerability to HIC need to be explored. Recent studies proved that low hydrogen ferritic steel (LHF) consumables can be used to weld Q&T steels, which can give very low hydrogen levels in the weld deposits. The use of ASS and LHF consumables will lead to distinct microstructures in their respective welds. This microstructural heterogeneity will have a drastic influence in the fatigue crack growth resistance of armour grade Q&T steel welds. Hence, in this investigation an attempt has been made to study the influence of welding consumables and welding processes on fatigue crack growth behaviour of armour grade Q&T Steel joints. Shielded metal arc welding (SMAW) and Flux cored arc welding (FCAW) were used for fabrication of joints using ASS and LHF consumables. The joints fabricated by SMAW process using LHF consumable exhibited superior fatigue crack growth resistance than all other joints.     

基于MDFT框架的海上能源通道航线动态决策建模与仿真

针对常规海上航线决策没有考虑决策选择过程的问题,引入多选择决策场理论（ MDFT）,构建了海上能源通道航线动态决策模型。基于信息完备、信息不确定和特殊情况等三种情景想定,进行了海上能源通道航线规划决策及其实验仿真。结果表明,决策过程受时间压力和信息质量的制约,时间压力会制约决策质量,同时还可能引起“偏好逆转”现象,信息不确定也会导致确定性决策。该模型不仅综合考虑了海上能源通道航线选择时需关注的各类要素,且模型参数可动态调整,进而能合理模拟真实的海上状况和决策过程。     

信息化条件下空战威胁评估指标体系

目标威胁评估是空战决策研究的重要组成部分,评价指标是进行威胁评估的前提和基础。根据现代空战的特点,借鉴网络中心战思想,从空间态势、物理域、信息域、认知域4个角度,构建了信息化条件下空战目标威胁评估指标体系,并对指标体系进行了完备性、合理性、有效性检验。通过实例分析表明威胁评估指标能较好地反映信息化条件下空中目标的实际威胁,为空战决策研究提供参考。     

基于向量相似度的组合赋权方法

针对多属性决策中属性权重的确定问题,提出了一种基于向量相似度的主、客观权重的集成方法。用权向量的相似度作为不同赋权方法重要性的度量,意义明确,计算简单,可操作性强。最后结合算例验证了此方法的有效性和实用性。     

行政复议机关在行政诉讼中的被告地位研究

行政复议制度具有其独立的功能价值,而我国现行法律关于经复议后如何确定行政诉讼被告的规定,却存在着许多弊端,使得这种功能价值很难体现。实践中,行政权的依法行使需要司法权强有力的监督,因此,有必要将行政复议的结果尤其是行政复议维持决定纳入司法审查范围。从行政诉讼法关于被告问题的规定和行政复议法中复议机关的职责责任方面对现行法律规定的完善进行了探讨。     

我国警卫工作改进历程考察与思考

在考察我国警卫工作改进历程的基础上,对警卫工作改进进行了深入思考。提出我国警卫工作改进始终坚持“既要保证安全,又不脱离群众”这一主题;始终坚持党委和政府的领导,坚持制度化、规范化建设;体现在路线警卫工作、住地警卫工作和现场警卫工作三个方面。     

A novel gradient approach for optimal design and sensitivity analysis of EWMA control charts

Conventional control charts are often designed to optimize out‐of‐control average run length (ARL), while constraining in‐control ARL to a desired value. The widely employed grid search approach in statistical process control (SPC) is time‐consuming with unsatisfactory accuracy. Although the simulation‐based ARL gradient estimators proposed by Fu and Hu [Manag Sci 45 (1999), 395–413] can alleviate this issue, it still requires a large number of simulation runs to significantly reduce the variance of gradient estimators. This article proposes a novel ARL gradient estimation approach based on integral equation for efficient analysis and design of control charts. Although this article compares with the results of Fu and Hu [Manag Sci 45 (1999), 395–413] based on the exponentially weighted moving average (EWMA) control chart, the proposed approach has wide applicability as it can generally fit into any control chart with Markovian property under any distributions. It is shown that the proposed method is able to provide a fast, accurate, and easy‐to‐implement algorithm for the design and analysis of EWMA charts, as compared to the simulation‐based gradient estimation method. Moreover, the proposed gradient estimation method facilitates the computation of high‐order derivatives that are valuable in sensitivity analysis. The code is written in Matlab, which is available on request. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 223–237, 2014     

基于马尔科夫决策的目标选择策略

目标选择是军事计划的关键要素之一。基于马尔科夫决策方法,解决具有复杂目标间关联的多阶段目标选择问题。使用与或树描述目标体系各层状态间的影响关联,并以目标体系整体失效为求解目的,建立了基于离散时间MDP的多阶段打击目标选择模型。在LRTDP算法基础上提出一种启发式方法,通过判断从当前目标体系状态到达体系失效状态的演化过程中的可能资源消耗和失败概率,来提供对当前状态的评估值,该方法能有效排除问题搜索空间中不能到达体系失效目的的中间状态,压缩了由于目标间复杂关联而增长的巨大状态空间。用实验验证了该方法有效性,实验结果表明,该方法直观实用,对目标间具有复杂关联关系的目标打击决策有一定参考价值。     

舰艇编队防空过程建模及分析

防空作战是大型水面舰艇编队的主要作战样式之一。运用PEPA(性能评价过程代数)方法对舰艇编队防空作战全过程进行有效建模,形式化描述了预警探测、情报传递、命令下达、防空拦截等作战主要过程。建立的PEPA模型具有层次化结构,考虑了要素间相互协作,体现了编队防空作战分布、并发的特点。通过对建立的PEPA模型进行性能指标选择和稳定状态分析,得到了不同因素对编队能力发挥的影响情况,获得了防空作战的基本要素组成,从而提供了一种解决舰艇编队问题的新方法。