直升机尾传动系扭转振动的分析

 在简化直升机尾传动系结构的基础上,根据轴段的扭转动力学方程,用分离变量法获得轴段的扭转主振型。再根据轴段、支点的扭转动力学方程和边界条件,用振型叠加原理求得尾传动系扭转振动的精确解,并进行了扭转振动分析。提出直升机的尾传动系是多个轴段和圆盘的串联系统。给出了尾传动系扭转频响函数的变化幅值的测试方法。     

一种改进的短时数据高精度测频算法

原短时数据高精度测频算法在某些频率范围内无法实现对频率的准确估计,分析了产生这一现象的原因,并提出了一种改进的短时数据高精度测频算法。在低信噪比条件下,改进算法可以实现对采样率范围内所有频率的高精度估计,其性能接近Cramer-Rao(CR)下界。     

GNSS航空应用的展望

全球导航卫星系统已获国际民航组织采纳。它能改善空中和地面的信息环境，ＧＮＳＳ将分阶段实施，并用某些民间设施增强。为了长远的保证，必须依靠民间自筹建成一个国际管理的民用ＧＮＳＳ，这是ＩＣＡＯ的目标，也是民航用户所期的。为了及时和有序地实现ＧＮＳＳ，国际上的使用与协调非常重要。     

CGI——一种交互图形设计的通用接口

 CGI(CADEMAS Graphics Interface)是一种通用的与设备独立的高级用户图形接口。我们将说明它与国际图形标准的区别。CGI已在几种图形仪上实现。本文侧重介绍CGI的IBM 5080版本,且说明它的特点。最后是若干工程实例。     

A novel compilation method of comprehensive mission spectrum of aero-engine maneuvering load based on use-related mission segment

Comprehensive Mission Spectrum (CMS) of an aero-engine can reflect the usage characteristics of the engine. It can provide load input for engine life prediction and accelerated mission test. In this paper, a novel compilation method of CMS of aero-engine maneuvering load based on mission segment is proposed. Firstly, the use-related Typical Mission Segment (TMS) of maneuvering load is divided and identified according to spectral characteristics. Secondly, the mathematical model of different kinds of TMS are established based on stochastic process theory. Finally, the CMS of maneuvering load is compiled based on TMS. The proposed method can accurately quantify the compilation of CMS. The compiled CMS shows good agreement with the original load spectrum. According to damage consistency inspection, the compiled CMS is consistent with the damage caused by the original load spectrum in terms of low cycle fatigue.     

The Experimental Satellite on Electro-magnetism Monitoring

The Experimental Satellite on Electromagnetism Monitoring (ESEM) was proposed in 2003 and proved in 2013 after 10-years' scientific demonstration. The ESEM mission was proposed to be the first satellite of space-based geophysical fields observation system in China with a lot of application prospects in earthquake science, geophysics, space sciences and so on. And coincide with the mission objectives, the satellite decides to use the Circular Sun Synchronous Orbit with an altitude of 507km and descending node time at 14:00LT. The payload assemble includes 8 instruments, Search-Coil Magnetometer, Electric Field Detector, High precision Magnetometer, GNSS occupation Receiver, Plasma Analyzer, Langmuir Probe, Energetic Particle Detector, and Three-frequency Transmitter. According to the planned schedule, the satellite is due to be launched in 2016-2017 and will be onboard operated for 5 years.      

内外双承力框架壳段先进自动铆接装配技术

针对运载火箭箭体结构壳段自动装配技术研究中,研究开发了内外双承力框架等复杂壳段先进自动铆接精细化编程技术;利用机器人高效建模仿真技术、工作区域先进识别技术、路径精细化设计技术.解决了铆接中大量依靠手工操作、产品质量一致性差、装配效率总体偏低、噪声污染严重等问题.     

空间太阳能电站经济性分析

空间太阳能电站作为一项在空间进行大规模太阳能收集、转化并通过无线方式将电能传输到地面电网的宏伟航天工程,其经济可行性是决定其能否大规模发展的主要因素之一。本文基于多旋转关节空间太阳能电站方案,提出空间太阳能电站全生命周期阶段划分和成本分析流程,初步分析得到空间太阳能电站的全部成本大约为2 500亿元,对应全寿命周期的发电量约为2 400亿度电,得到的单位电量的成本约为1元/度电。     

基于电容加载的UHF-RFID近场长天线设计

针对近场长天线的电流相位分布空间跨度大这一难点,设计了一款基于多电容加载的超高频(Ultra-high frequency,UHF)频段近场长天线。通过对长度为250mm微带传输线在间隔48.8mm处分段加载1.6pF电容,利用电容对电流的相位补偿作用改善了天线近场均匀性。在端口增加金属匹配枝节及负载电阻进行阻抗匹配。仿真及实测表明,该长天线回波损耗在918~933 MHz频段内低于-10dB,长天线正上方300mm处近场场强差值最大仅为3.2dB,天线正上方不同位置处最大读取距离差值波动不超过95mm,验证了该天线良好的近场均匀性。搭建射频识别(Radio frequency identification,RFID)系统并进行测试,进一步验证该款长天线在近距离RFID系统中的实用性。     

弹道目标航迹片段关联及优化

多弹道目标跟踪伴随着速度快、密集程度高以及测量误差大等因素,在跟踪过程中发生航迹中断是一个很普遍的现象.在未知导弹任何先验信息前提下如何将中断前后的航迹片段进行关联,提高航迹的连续性已成为亟待解决的难题.针对该问题提出了一种实时的离散最优关联算法,它利用速度信息对中断前后弹道外推航迹进行粗关联;将对数似然函数作为关联代...