A novel formulation of material nonlinear analysis in structural mechanics

This article demonstrates a novel approach for material nonlinear analysis. This analysis procedure eliminates tedious and lengthy step by step incremental and then iterative procedure adopted classically and gives direct results in the linear as well as in nonlinear range of the material behavior. Use of elastic moduli is eliminated. Instead, stress and strain functions are used as the material input in the analysis procedure. These stress and strain functions are directly derived from the stress-strain behavior of the material by the method of curve fitting. This way, the whole stress-strain diagram is utilized in the analysis which naturally exposes the response of structure when loading is in nonlinear range of the material behavior. It is found that it is an excellent computational procedure adopted so far for material nonlinear analysis which gives very accurate results, easy to adopt and simple in calculations. The method eliminates all types of linearity assumptions in basic derivations of equations and hence, eliminates all types of possibility of errors in the analysis procedure as well. As it is required to know stress distribution in the structural body by proper modelling and structural idealization, the proposed analysis approach can be regarded as stress-based analysis procedure. Basic problems such as uniaxial problem, beam bending, and torsion problems are solved. It is found that approach is very suitable for solving the problems of fracture mechanics. Energy release rate for plate with center crack and double cantilever beam specimen is also evaluated. The approach solves the fracture problem with relative ease in strength of material style calculations. For all problems, results are compared with the classical displacement-based liner theory.     

国内装备采购研究现状与趋势研究——基于CiteSpace知识图谱软件的可视化分析

本文利用CiteSpace知识图谱分析和可视化工具,从时间分布、期刊来源和作者机构等方面对CNKI中文期刊全文数据库2001年1月1日至2020年6月30日间收录的以"装备采购"为关键词的642篇学术论文及文献进行数据可视化分析,并通过关键词词频共现分析对该领域的高频关键词进行了词频统计。在利用CiteSpace软件对"装备采购"相关文献进行统计分析后,详细论述了装备采购研究的发展趋势,并总结出目前军队装备采购研究的现状与不足,如军队内部科研力量作为装备采购领域研究的核心组成部分,相互间缺乏交流研究;装备采购领域研究方向多元,但基础理论、概念研究不够深入等。在此基础上梳理出优化后期装备采购领域研究发展的建议,以期为完善军队装备采购领域的研究工作提供一定参考。     

Field test and probabilistic analysis of irregular steel debris casualty risks from a person-borne improvised explosive device

Person-borne improvised explosive devices (PBIEDs) are often used in terrorist attacks in Western countries. This study aims to predict the trajectories of PBIED fragments and the subsequent safety risks for people exposed to this hazard. An explosive field test with a typical PBIED composed of a plastic explosive charge and steel nut enhancements was performed to record initial fragment behaviour, including positions, velocity, and trajectory angles. These data were used to predict the full trajectory of PBIED fragments using a probabilistic analysis. In the probabilistic analyses a probability of fatality or serious injury was computed. Based on the results presented, many practical conclusions can be drawn, for instance, regarding safe evacuation distances if a person were exposed to a suspected PBIED.     

现代军事情报处理方法中的语言、语音技术

军事情报的收集、处理和分析是情报部门的重要工作,当今时代,依靠人工搜集处理方法在效率上已经不能满足需要,采用先进的信息处理技术对情报进行自动处理技术正是解决这一问题的有效途径。大部分的情报载体是文字和语音．因此自然语言和语音处理技术在情报处理方面发挥着重要作用。针对军事情报处理方法中的语言、语音处理技术进行简单的介绍,包括机器翻译、信息检索,语音分析、语音识别等方面。     

可拓工程方法在效能-费用权衡中的应用

介绍可拓学及物元理论,提出用可拓工程方法对武器装备效能-费用进行权衡分析。建立了装备效费权衡分析的高阶复合物元模型,对初始效费方案进行了延拓,提出可拓特征集的概念。在此基础上,对效能-费用方案进行可拓聚类分析。     

深基坑预应力锚索支护对临近既有建筑影响的数值分析

通过利用Ansys有限元软件对某基坑的开挖过程进行数值模拟,对预应力锚索桩支护体系对既有建筑物基础的影响进行了分析,并且与锚索不施加预应力的情况进行了对比,得出了锚索施加预应力可以减小既有建筑物的地基两侧的变形差。但是锚索倾角太小或锚固段完全位于建筑下方,会降低锚索的预期效果,有可能导致建筑物开裂。所以应考虑锚索的倾角和锚固段的位置对建筑的影响。     

基于模糊综合评判的舰艇电子战系统效能评估

舰艇电子战能力是现代舰艇综合作战能力的重要组成部分,为了准确评估舰艇电子战系统的效能,探讨现代战争条件下舰艇电子战系统的定量评估方法非常重要。应用模糊数学理论和层次分析法对舰艇电子战系统的效能进行评估,建立舰艇电子战系统的评价指标体系和三级评估模型,对定量指标和定性指标的隶属度计算进行了区分,并通过实例演示了该模型的具体应用过程。实例结果显示此方法是非常有效的,为这方面的进一步研究具有一定的借鉴意义。     

基于SEA的舰载C3I系统防空作战效能评估模型

现代海战中,空中目标对舰艇的威胁越来越大,舰艇的防空作战能力已成为衡量其综合作战能力的主要指标。而C3I系统作为舰艇的指挥中枢,其性能直接决定着舰艇防空作战的成败。根据现代海战中空中目标的武器作战使用方式,并针对SEA方法的要求,提出了评估C3I系统在防空作战时系统效能的三个主要性能量度(MOP),通过分析C3I系统在防空作战时的特点,建立了评估C3I系统防空作战效能的SEA方法模型。并利用该模型比较了不同的C3I系统的作战效能,对结果进行了简要分析,证明了SEA方法模型对舰载防空C3I系统进行效能评估的可行性。     

要地防空群对敌主攻方向确定度分析

针对目前防空作战中对敌主攻方向判断的困难和复杂性,运用系统工程理论、模糊数学等理论探索要地防空群对敌主攻方向定量判断问题。全面分析了影响敌主攻方向选取的诸多因素,建立了分析指标体系和模糊综合分析模型,为判断敌主攻方向提供了一种新的思路和定量分析的方法。在影响敌空袭目标选取的因素中,不确定和灰色的因素多,模糊综合分析方法采取定量与定性分析相结合的办法,把定性的因素定量化,较科学地解决了要地防空群对敌主攻方向判断的问题,进一步丰富了防空兵作战指挥精确决策理论。     

装备战场损伤的解析分析方法研究

为了提高装备战损模拟的效率,以蒙特卡洛方法为基础,构建了关于装备战损的解析模型。首先采用序贯法优化了仿真次数,以便以较少的仿真次数获得较高的仿真精度;分析了单因素对于装备损伤的影响,并建立了一元回归模型;采用正交试验分析了多因素之间的交互作用,并综合一元回归模型得出了装备战损的多元回归模型;最后结合弹着点分布模型与多元回归模型,建立了装备战损的解析模型,并通过实例验证了解析模型的正确性。