Smalltalk-80 的形式语义研究

Smalltalk-80是原型的面向对象程序设计语言和环境。本文简要地介绍了Smalltalk-80的基本概念和抽象文法,给出了其形式模型,并基于该模型描述了Smalltalk-80的静态指称语义和动态指称语义。     

隐蔽锥扫雷达波束的交叉点电平

本文根据隐蔽锥扫雷达天线的工作原理,从方向性函数出发,分析了接收状态下高频馈电网络中,和差信号的幅相特性与隐蔽锥扫波束交叉点电平的关系,从而对不能自动跟踪的隐蔽锥扫雷达,从天馈系统方面分析了原因,并为设计和部队维修提供了理论根据和有效方法。     

舰舰导弹武器系统作战效能评估

在规定舰舰导弹典型作战任务剖面的情况下,运用美国工业武器系统效能咨询委员会评估武器系统效能的方法,建立舰舰导弹武器系统作战效能评估数学模型,并进行了算例验证和分析。结果表明:该模型可有效评估舰舰导弹武器系统作战效能,为舰舰导弹武器系统作战效能的评估提供了有效且便于操作的方法。     

When are observed failures more informative than observed survivals?

A framework involving independent competing risks permits observing failures due to a specific cause and failures due to a competing cause, which constitute survival times from the cause of primary interest. Is observing more failures more informative than observing survivals? Intuitively, due to the definitiveness of failures, the answer seems to be the former. However, it has been shown before that this intuition holds when estimating the mean but not the failure rate of the exponential model with a gamma prior distribution for the failure rate. In this article, we address this question at a more general level. We show that for a certain class of distributions failures can be more informative than survivals for prediction of life length and vice versa for some others. We also show that for a large class of lifetime models, failure is less informative than survival for estimating the proportional hazards parameter with gamma, Jeffreys, and uniform priors. We further show that, for this class of lifetime models, on average, failure is more informative than survival for parameter estimation and for prediction. These results imply that the inferential purpose and properties of the lifetime distribution are germane for conducting life tests. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

On the nature and scope of defence economics

Defence economics uses the tools of economics to study the defence sector and its domestic and international implications. Simple models require careful application in defence economics, since indirect effects may have counterintuitive impacts. For example, while certain arms races can lead to the outbreak of war, others may have the counterintuitive effect of discouraging the outbreak of war owing to mutual deterrence.

The world is now multipolar rather than bipolar, analogous to an oligopoly situation. This multipolar world can be analyzed by a qualitative characteristic function, where the formation of a potential coalition allows study of the shift from conflict to cooperation in international relations. Some new issues to be considered in this framework include accidental nuclear war, potential arms races and conflicts in the third world, and the proliferation of chemical weapons and missiles.     

内腐蚀缺陷尺寸对DN150承插管线承压能力的影响

为了科学地指导DN150承插管线的使用与管理,采用非线性有限元法对带内腐蚀缺陷的DN150承插管线进行了剩余强度的评估。通过分析和计算,研究了腐蚀缺陷宽度、长度和深度对管线极限承载能力的影响。结果表明：腐蚀缺陷宽度对DN150承插管线的承载能力影响很小,可忽略不计;随着腐蚀缺陷长度的增加,管线的承载能力略微减小,当缺陷长度达到150mm,管道失效压力基本不变;随着腐蚀缺陷深度的增加,管道失效压力呈线性递减,其对管道失效压力的影响程度远远大于腐蚀缺陷长度。     

吊放声纳主动工作模式探测域建模与仿真

水声环境对于吊放声纳搜潜效果影响很大,以往的水声环境对吊声探测影响建模尚未涉及吊声立体探测域,不能为吊声搜潜战术研究提供有效支撑。在对声传播损失、海洋环境噪声和混响进行深入分析和建模的基础上,根据吊声探测机理建立了主动探测概率模型,仿真分析了吊声主动探测概率的三维空间分布,并提出了吊声搜潜战术应以三维非连续探测域为基础,结合战法实验等新手段进行不确定性研究的建议。     

基于功能的网格服务匹配算法

网格环境下,服务功能匹配效果决定着网格服务质量,在分析了网格服务匹配方法中基于推理的匹配算法和相似度匹配方法中基于距离的匹配算法后,对这两种算法的精确度、复杂度和匹配效率进行了分析和比较.结合这两种算法,提出了服务功能匹配改进算法,该算法通过采用细化匹配粒度,引入深度因素等方法,增加了匹配精确度.通过实验模拟,查准率和查全率上表明该改进算法具有一定优越性.     

潜艇在水面目标位置散布概率密度的计算方法

潜艇声纳在较远距离上发现水面目标时,探测和解算的目标运动要素具有较大的误差.利用泰勒公式,将目标位置计算公式进行简化处理,结合概率论的相关理论,求解目标位置散布概率密度.针对典型战术态势,计算不同时刻目标位置散布概率密度,绘制概率密度图,与目标位置散布仿真图进行对比.     

火控雷达协同防空目标跟踪技术

针对火控雷达抗反辐射导弹的对抗要求,将雷达组网理论应用于火控雷达,提出了火控雷达协同防空目标跟踪方法.首先分析了火控雷达目标跟踪原理,同时给出了跟踪性能的评价指标;其次,为了克服单部雷达的局限性研究了组网火控雷达目标跟踪方法;而后,研究了不同的交替周期对系统的影响;最后对不同工作模式的跟踪效果进行了仿真.结果证明采用组网雷达目标跟踪方法可以同时实现对反辐射导弹载机的准确跟踪和对反辐射导弹的有效对抗.