多芯片焊球阵列封装体受热载荷作用数值模拟

针对典型高密度多芯片BGA(焊球阵列)封装体建立三维有限元分析模型,研究不同尺寸封装体在稳态热载荷作用下的结构变形和应力情况,在此基础上引入包含等效梁和危险焊球真实几何形状和间距等在内的简化模型以进行序列分析,研究各设计参数对力学参量的影响。数值结果反映了封装体应力分布及其变化特点,表明影响封装体变形和应力的主要参数;提出的建模方法简便有效,可以方便地用来分析不同类型的BGA封装,并扩展应用至不同的分析目的,为此种结构的设计和优化提供一定参考。     

大口径顶置火炮输弹机动力学研究

为解决大口径顶置火炮弹药自动装填系统的关键技术问题,提出了大口径顶置火炮输弹机各工作阶段的力学模型和动力学方程,并通过输弹速度与时间的计算分析,得到了3种输弹方式的输弹速度与时间关系曲线,其结果对大口径顶置火炮供输弹系统的研究具有较大参考价值。     

嵌入式设备驱动程序独立加载技术

针对嵌入式软件开发的特点,运用独立加载技术实现对嵌入式系统驱动程序代码的独立加载和升级。设备驱动程序独立加载技术打破了多个嵌入式软件模块合编成单个目标文件的传统模式,将各个软件模块进行独立和分离,通过硬件自动扫描引擎自动检测硬件设备,程序加载器构建设备链表和驱动程序链表,并根据配置信息分别加载相应的驱动程序和应用程序,实现多个嵌入式设备驱动程序的独立加载。嵌入式设备驱动程序独立加载技术的研究和应用为各系统组件和应用模块的独立开发以及软件模块动态扩展和独立升级提供了捷径,降低了嵌入式软件协作的人力和时间成本。     

水中兵器延寿样本的装载可靠度鉴定试验方案

针对延寿样本子样少,按经典GJB899法对装载可靠度鉴定需要较长的试验时间这一实际情况,提出了一种减少试验时间的Bayes方法.该方法通过挖掘延寿前装载失效率信息,确定先验分布,再开展陆上加速装载试验以增加装载信息,并结合实际装载信息制定了装载可靠度鉴定试验新方案.实例计算表明:在确保鉴定效果的前提下,新方法可在较小的延寿样本条件下快速完成装载可靠度鉴定工作,满足水中兵器延寿工程的实际需要.     

MACROECONOMIC ASPECTS OF INTERNAL CONFLICTS: A CONCEPTUALISATION

This exploratory paper outlines the special macroeconomic features of countries populated by two groups of people engaged in internal conflict yet forming a central government for generating benefits that cannot be privately attained. Each group exerts an influence on the central government in accordance with its relative military strength. The central government collects taxes, exports the country’s natural resources and tourist attractions, attracts external grants and loans, and distributes the net revenues between the rival groups. The paper highlights the implications of the groups’ investment in military strength for the state’s net revenues and their distribution, for the state’s external debt, and for the groups’ ability to maintain and increase their ranks, production capital and per capita income.     

爆炸载荷作用下的船用吸能防护结构

重要舰船或舰船的重要部位采用吸能防护结构的必要性已逐渐被人们所认识和接受。防护结构性能好坏的主要指标是培构总能量吸收量和比耗能,本文分析了3种船用吸能防护结构在爆炸最荷作用下的破坏形式,给出了相应的能量吸收估算公式及计算蛄果,比较了等重量下不同防护结构的吸能量和比耗能,从而为船用吸能防护结构用于抗爆炸设计提供了依据和方法。     

混合遗传算法在大型运输机装载问题中的运用

为解决大型运输机装载方案的制定问题,构建了考虑飞机重心、飞机载重量、货舱容积、货物摆放方向、承压能力、装载优先级、货物底置位置和系留等现实约束的装载方案数学模型,提出了一种新的融合整体退火选择方式和对交叉、变异概率进行自适应处理的混合遗传算法,并将此方法运用到两个货物装载算例中。仿真实例表明:该混合遗传算法方法为大型运输机装载方案制定选择提供了一种科学有效的决策方法。     

Effect of change of sand properties on travel distance of ricocheted debris

The debris from exploded buildings can ricochet after colliding with the ground, thus increasing the debris travel distance and danger from any associated impacts or collisions. To reduce this danger, the travel distance of ricocheted debris must be accurately predicted. This study analyzed the change in the travel distance of ricocheted concrete debris relative to changes in the properties of a sand medium. Direct shear tests were conducted to measure the change in internal friction angle as a function of temperature and water content of the sand. Finite element analysis (FEA) was then applied to these variables to predict the speed and angle of the debris after ricochet. The FEA results were compared with results of low-speed ricochet experiments, which employed variable temperature and water content. The travel distance of the debris was calculated using MATLAB, via trajectory equations considering the drag coefficient. As the internal friction angle decreased, the shear stress decreased, leading to deeper penetration of the debris into the sand. As the loss of kinetic energy increased, the velocity and travel distance of the ricocheted debris decreased. Changes in the ricochet velocity and travel distance of the debris, according to changes in the internal friction angle, indicated that the debris was affected by the environment.     

航空轮胎用橡胶弹性体Mullins效应动态加载方法

航空轮胎用橡胶弹性体在服役过程中遭受严苛的动态循环工况。为了研究弹性体在此工况下的力学响应特征和损伤机理,提出基于应力波作用的Mullins效应动态加载实验方法。根据应力波传导与作用特征,采用Hopkinson压杆加载思路,设计和配置了各单元尺寸参数,进而搭建可用于橡胶弹性体材料动态循环加载的实验系统,并开展了航空轮胎用丁苯橡胶的动态循环加载试验。基于试验信号分析发现：加载系统实现了弹性体材料Mullins效应动态应变递增的试验加载。最后开展加载测试参数的影响因素分析,结果表明通过优化系统各单元可实现Mullins效应的动态加、卸载参数的控制。     

红外脉冲强光辐射产生技术研究

定向红外脉冲强光辐射技术是定向红外对抗中的关键技术,主要用来破坏敌方精确制导武器或C4I系统的红外传感器。本文进行了三种产生技术的研究,即爆炸激励惰性气体,多丝电爆激励惰性气体和多点同步爆燃药物。在同步爆燃产生技术的研究中,当有效载荷弹药为0.2kg时,在距离源50m处得到三个波段(1～3、3～5、8～12μm)的辐射强度为(2.00～3.55)×l05W／Sr,脉冲半高宽为约20ms的强红外辐射脉冲。