Monitoring censored lifetime data with a weighted‐likelihood scheme

Lifetime experiments are common in many research areas and industrial applications. Recently, process monitoring for lifetime observations has received increasing attention. However, some existing methods are inadequate as neither their in control (IC) nor out of control (OC) performance is satisfactory. In addition, the challenges associated with designing robust and flexible control schemes have yet to be fully addressed. To overcome these limitations, this article utilizes a newly developed weighted likelihood ratio test, and proposes a novel monitoring strategy that automatically combines the likelihood of past samples with the exponential weighted sum average scheme. The proposed Censored Observation‐based Weighted‐Likelihood (COWL) control chart gives desirable IC and OC performances and is robust under various scenarios. In addition, a self‐starting control chart is introduced to cope with the problem of insufficient reference samples. Our simulation shows a stronger power in detecting changes in the censored lifetime data using our scheme than using other alternatives. A real industrial example based on the breaking strength of carbon fiber also demonstrates the effectiveness of the proposed method. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 631–646, 2017     

Nicholas John Spykman,the Balance of Power,and International Order

Nicholas John Spykman was probably America’s finest geopolitical theorist of the twentieth century, even though he was an active participant over the course only of five years (1938–43). He is rightly viewed as a worthy intellectual successor to Sir Halford Mackinder in Britain. Spykman originated the (Eurasian) Rimland concept, which is of continuing political and strategic utility today. He was controversial and notably outspoken while his writings make it quite clear that his concern with the acquisition of power was contextualised by serious concerns for world order.     

Evaluating state willingness to pursue space weapons

Many studies exist which evaluate the domain of space from a political perspective in order to advocate for a certain position regarding what states ought to do or not do in space. Few studies exist which address how states actually behave with regard to outer space. In an attempt to fill this gap in the literature, the present study evaluates the determinants of state space behavior. The results identify a blend of the realist pursuit of power and liberal normative restrains acting on state space behavior.     

The United States and Humanitarian Assistance and Disaster Relief (HADR) in East Asia: Connecting Coercive and Non-Coercive Uses of Military Power

Abstract

Humanitarian Assistance and Disaster Relief (HADR) is increasingly important for East Asian militaries, but there is little scholarship on how HADR relates to broader national strategies. This article considers US involvement in HADR in East Asia in relation to changing conceptions of national power. HADR is frequently described as use of ‘hard’ military assets to further soft power goals. Looking at recent US experiences, this article shows that HADR also serves instrumental ends linked to traditional military objectives. Rather than considering power as ‘soft’ or ‘hard’, it argues that HADR illustrates connections between non-coercive and coercive uses of military power.     

基于反馈线性化的深海潜标姿态滑模控制

针对潜标空间运动的强非线性及数学模型中存在的干扰不确定性为控制带来的挑战,提出了一种基于反馈线性化的深海潜标姿态滑模控制律,并编程进行了仿真及与输入输出线性化控制方法进行比较,结果表明,两种方法均能将潜标控制到参考姿态,滑模控制对系统的不确定性干扰和执行器滞后具有更好的鲁棒性。另外,通过程序可以数值模拟的方式观察潜标在控制过程中的水动力、力矩,潜标姿态、空间运动轨迹、缆索动力学特征等信息,为客观分析潜标的控制与水动力机理提供了支撑。     

炮瞄雷达试验数据处理中有关问题的探讨

结合炮瞄雷达国家军用标准和靶场炮瞄雷达试验,对炮瞄雷达精度试验数据处理中的误差分组统计方法、样本大小选取和异常数据点处理等问题进行了探讨,并且提出了相应的处理方法     

BTT导弹状态反馈H_∞控制自动驾驶仪设计

针对倾斜转弯(BTT)导弹自动驾驶仪的抗干扰性和鲁棒性问题,以考虑耦合的情况下建立的更接近于实际的导弹数学模型为基础,将通道间的耦合作为干扰,在弹道特征点上对导弹模型进行解耦和线性化,得到各个通道的数学模型;设计基于线性矩阵不等式(LMI)的状态反馈H_∞控制自动驾驶仪,搭建全耦合状态下的三通道仿真模型,并进行联合仿真研究。结果表明所设计的状态反馈H_∞控制自动驾驶仪能够实现对导弹制导指令的有效跟踪,满足BTT导弹控制的要求。     

基于HHT军用电源逆变器电力谐波检测分析

电能逆变器是军用电源系统的核心,为提高军用电源输出电压电力谐波分析效果,提出改进型希尔伯特-黄变换(HHT)方法的检测分析方法,并设计基于LabVIEW平台的电压谐波检测和分析装置。在研究双闭环控制策略的基础上,针对模态混叠问题,先使用数字滤波器对输出电压信号进行预处理,再进行改进HHT分析,得到输出电压谐波分量的幅频分布,并利用MATLAB对军用电源逆变器模型进行仿真。结果表明该方法可以对军用电源变换器输出谐波分量实时检测和分析,计算精度高,分析效果好,为下一步的谐波抑制方法研究提供有力支持。     

符号执行火控系统诸元解算程序测试用例生成技术

火控系统作为各种武器装备的中枢和大脑,控制着武器系统的运转,其有效性直接关系着射击的成败甚至武器系统的综合效能。诸元解算程序是将各种输入条件依据弹道模型经过多次迭代转换为射击诸元,由于其复杂性,当前软件测试用例只是在几个关键点上进行校验,很难覆盖程序所有分支和路径,存在着测试不充分。针对这个问题,提出了一种基于符号执行的用例自动生成技术,结合解弹道方程组约束条件和程序分支控制变量使用符号执行框架内能够得到覆盖所有可能的执行路径,从而保证测试的充分性。