电子产品振动应力筛选试验方法应用探讨

正确的振动应力筛选试验方法在电子产品研制工程中扮演着重要的角色。文章从GJB 1032给出的筛选的目的和对象着手分析,讨论振动应力筛选的条件和方法;就工程中常见的几种"欠筛选"和"过筛选"情况进行深入探讨,分析研究了几种正确的振动应力筛选方法。根据产品实际情况选择正确的筛选条件,并采用相应的带谷控制方法,能够避免欠筛选和过筛选,完成规定的筛选任务。     

An Electro-Hydraulic Actuator for the TVC of a Throttlable Kerolox Rocket Engine

An electro-hydraulic actuator for the thrust vector control(TVC)of a throttlable kerolox rocket engine is introduced in this paper.The creative feature is an in...     

二维非线性离散声子晶体色散摄动分析

弹性波在声子晶体中的传播方式可由其色散关系决定,从二维无限周期结构的波动方程出发,通过引入Bloch理论与小参数摄动展开法,提出了一种分析非线性离散型声子晶体色散关系的一阶近似摄动法。得到了一阶近似的色散关系与频散曲线,以分析不同方向上的阻抗配置与非线性系数对频散及群速度的影响。分别以二维单原子网格、二维双原子二自由度网格和二维双原子四自由度网格为例,得到了它们的一阶频散曲线,色散结果显示带隙及传播方向与波幅相关。同时结合数值积分解验证了其在有限波幅谐波激励下解的精度。     

高超声速飞行器的抗饱和切换控制

针对高超声速飞行器动力学模型强非线性及飞行过程中系统参数变化剧烈的问题,提出一种根据飞行包线分区并分别建立独立的子系统的切换系统建模方式和抗饱和切换控制方法。通过缩小子系统模型对应的飞行空域,降低系统线性化以及参数变化带来的影响,使得线性控制理论能够应用于高超声速飞行器的控制器设计当中。考虑到飞行过程中可能会遇到的执行器饱和问题,本文在切换系统模型的基础上,为高超声速飞行器设计了抗饱和切换控制器。仿真算例验证了提出的切换系统模型的优越性及抗饱和控制器的有效性。     

浅谈廊坊电子信息产业的现状与发展

电子信息产业发展对当今世界经济发展起着十分重要的作用.如何加快电子信息产业发展,对保持经济持续快速增长,加快推进工业化进程具有十分重要的意义.本文立足于廊坊电子信息产业发展的现状,对未来如何加快发展廊坊电子信息产业提出自己的想法和建议.     

月球探测器动力下降段最优轨迹参数化方法

为保证月球探测器进入姿态调整段时具有充分的高度与速度余量,本文提出一种基于控制变量参数化的月球探测器动力下降段最优轨迹求解方法.在三维探测器软着陆动力学模型基础上,将月球探测器软着陆制导律设计等效为燃料最优约束下的探测器俯仰角控制问题,利用控制变量参数化(Control Variables Parameterizati...     

基于压电叠层作动器的柔性自旋导弹振动控制

针对柔性自旋导弹弹性振动问题,提出将压电叠层作动器应用于导弹弹性振动控制方法.将导弹简化为非均匀自由-自由Timoshenko梁模型,考虑陀螺效应和推力作用,将压电叠层作动器应用于导弹弹性振动,基于有限元方法建立含有压电叠层作动器的柔性自旋导弹动力学模型,同时设计模糊滑模控制器,对质量偏心引起的不平衡响应进行数值仿真,...     

基于TOPSIS的导弹威胁评估方法研究

在研究战术弹道导弹威胁评估诸因素的基础上,分析了多属性决策方法的机理,提出了利用逼近理想解的排序法理论对战术弹道导弹威胁程度进行评估。文中给出了数学建模的方法、步骤,并针对具体事例进行了计算和分析,所得的结果合理、符合实际,证明了这种评估算法对战术弹道导弹威胁评估的可行性。     

Design of Drilling and Riveting Multi-functional End Effector for CFRP and Aluminum Components in Robotic Aircraft Assembly

To fulfill the demands for higher quality,efficiency and flexibility in aviation industry,a multi-functional end effector is designed to automate the drilling and riveting processes in assembling carbon fiber reinforced polymer(CFRP)and aluminum components for a robotic aircraft assembly system.To meet the specific functional requirements for blind rivet installation on CFRP and aluminum materials,additional modules are incorporated on the end effector aside of the basic processing modules for drilling.And all of these processing modules allow for a onestep-drilling-countersinking process,hole inspection,automatic rivet feed,rivet geometry check,sealant application,rivet insertion and installation.Besides,to guarantee the better quality of the hole drilled and joints riveted,several online detection and adjustment measures are applied to this end effector,including the reference detection and perpendicular calibration,which could effectively ensure the positioning precision and perpendicular accuracy as demanded.Finally,the test result shows that this end effector is capable of producing each hole to a positioning precision within ±0.5 mm,aperpendicular accuracy within 0.3°,a diameter tolerance of H8,and a countersink depth tolerance of±0.01 mm.Moreover,it could drill and rivet up to three joints per minute,with acceptable shearing and tensile strength.     

Development and Prospectives of Ultra-High-Speed Grinding Technology

Ultra-high-speed grinding(UHSG)is a significant and powerful machining method in view of the enhanced productivity and precision demands.Previous researches regarding formation mechanisms and crucial technologies are comprehensively and thoroughly summarized to highlight state-of-art technology of UHSG.On the basis of the interdependence between process and machine innovations,theoretically,grinding mechanisms in strain hardening,strain rate strengthening,thermal softening,size effect and process characteristics need more in-depth studies to clarify the dominance of UHSG.Technically,CFRP wheel integrating with the brazed bonding has a prominent advantage in bonding strength and grit′s configuration over vitrified bonding,which would be superior in UHSG.Furthermore,external high pressure cooling combining with inner jet cooling methods,accompanied by scraper plates to alleviate the effect of air boundary,are crucial and practical measures for realizing effective cooling in UHSG.Grinding processes,especially those being related to grinding parameters and precise in-process measuring approaches,are also prerequisite for fitting and investigation of UHSG.