流量转速参数信号调理技术

液体火箭发动机试验中,流量和转速传感器输出的信号为不规则的频率信号,对不规则频率信号的调理是准确测量的关键环节。介绍了液氧煤油发动机地面试验中流量和转速参数信号的调理技术,重点阐述频率信号调理器的原理、功能、设计要点及调试方法,给出了频率信号调理器的关键环节原理图。使用这种频率信号调理器对液氧煤油发动机试验中流量和转速传感器输出的频率信号直接进行调理,保证了频率型参数的准确测量。     

China's Meteorological Satellite Application System

(Continued) Applications In Global Environment And Natural Disaster Monitoring 1)Application in world crop yield estimation China is now one of the few nations in the world that can provide operational service with both GEO and polar-orbit meteorological satellites.Global data obtained by FY-1C and FY-1D satellites, is widely used in environmental and natural disaster monitoring,such as forest and grassland fire monitoring,and severe weather events monitoring.This data     

国外卫星星座自主运行技术发展综述

综述国外卫星星座自主运行技术的研究和发展情况,重点介绍了导航星座、移动通信星座和区域覆盖星座的自主导航和自主轨道控制技术的发展现状,并对实现星座自主控制的关键技术进行了分析。这为我国发展星座自主控制技术提供参考。     

MIMO系统功率比特自适应算法研究

发射功率受限的自适应调制系统,由于调制方式有限,实际使用的发射功率通常小于受限的发射功率,对这一部分剩余功率进行再分配和利用,能够提高频谱效率。文章对M IMO系统中功率和比特自适应算法进行了研究,提出对剩余功率在空域进行再分配的自适应算法。仿真结果表明,在空域采用等功率分配,再进行空域剩余功率再分配,能够提高频谱效率,并且复杂度低,易于实现。     

利用6S进行月光条件下遥感器信号模拟研究

以太阳为光源的卫星遥感器,可以采用6S或MODTRAN等辐射传输计算软件对其入瞳处的辐亮度进行计算。而在微光或月光条件下,遥感器是对观测目标反射的月亮辐射进行遥感观测,因此在进行辐射传输计算时需要代入月球的辐照度数据。可以利用已公布的月球表面反射率和已知的大气层外太阳辐照度来计算月球辐照度,并对6S辐射传输计算进行适当的修改进行计算。通过对月球辐照度计算原理进行了详细的描述并计算得到了波长在0.250μm~1.500μm范围内的月球表面辐照度,并给出了一个宽波段遥感器的微光动态范围。     

基于知识集成模型的产品快速设计

为提升现有CAD(Computer-Aided Design)系统对设计知识的重用能力,提出 了设计知识的分层描述和集成建模方案,并给出了具体实施方法.将设计知识划分到构型层 、设计层和造型层3个抽象层次,基于UG(Unigraphics)平台的知识熔接语言(KFL,Knowl edge Fusion Language)和Open++实现了各层设计知识的描述与集成.构建了知识集成模型 的创建和重用支撑系统框架.作为应用实例,在UG平台上开发了专用减速器快速设计系统.      

基于Web服务的E-Police系统架构

传统电子警察系统由于过分依赖单一服务器,在系统运算、网络传输以及存储容量上难以满足海量数据的需求.将Web Service技术应用到电子警察系统,设计了各前端节点对等的集群式服务器加单一后端客户处理机模式的E-Police电子警察系统架构,提出了计算服务、存储服务和查询服务;松散耦合的E-Police系统以3种服务的实现为核心,系统依靠大量前端节点承担主要工作,提高了资源利用率;通过Web服务的准备、发布和建立3步流程,实现了一套完整的任务、资源和数据流管理方案,解决了传统系统计算性能、存储容量与图像质量三者难以平衡的问题.      

With a grain of salt: what halite has to offer to discussions on the origin of life

This experimental study investigated how the dynamics of the crystallization of the evaporite mineral halite could affect the accumulation and preservation of organic macromolecules present in the crystallizing solution. Halite was grown under controlled conditions in the presence of polymer nanoparticles that acted as an analog to protocellular material. Optical microscopy, atomic force microscopy, and laser scanning confocal fluorescence microscopy were used to trace the localization of the nanoparticles during and after growth of halite crystals. The present study revealed that the organic nanoparticles were not regularly incorporated within the halite, but were very concentrated on its surfaces. Their distribution was controlled dominantly by the morphologic surface features of the mineral rather than by specific molecular interactions with an atomic plane of the mineral. This means that the distribution of organic molecules was controlled by surfaces like those of halite's evaporitic growth forms. The experiments with halite also demonstrated that a mineral need not continuously incorporate organic molecules during its crystallization to preserve those molecules: After rejection by (non-incorporation into) the crystallizing halite, the organic nanoparticles increased in concentration in the evaporating brine. They ultimately either adsorbed in rectilinear patterns onto the hopper-enhanced surfaces and along discontinuities within the crystals, or they were encapsulated within fluid inclusions. Of additional importance in origin-of-life considerations is the fact that halite in the natural environment rapidly can change its role from that of a protective repository (in the absence of water) to that of a source of organic particles (as soon as water is present) when the mineral dissolves.     

交会对接远距离导引精度分析

为确定交会对接任务地面远距离导引控制可达到的精度,分析了影响精度的误差因素;提出了利用简化动力学模型、采用拟平均根数法和协方差法进行误差传播计算的方法;推导了误差传播和误差分析数学模型;进行了仿真计算.结果表明:远距离导引终点精度主要由传播误差决定,在一定初始条件下,当外推时间小于6 h时,终点位置精度可达到2~5 km,速度精度可达到2~3 m/s;误差传播中,沿迹和径向误差因素占主要成份,且随外推时间增加沿迹误差影响逐渐增大;终点精度的提高应从抑制沿迹、径向误差着手.提出的地面导引控制精度分析方法综合考虑了各种误差因素,计算便捷,适用于工程方案设计阶段的精度分析与估计.      

闭路制导在小型固体运载火箭中的应用

固体运载火箭发动机推力偏差和秒耗量偏差大,导致关机点时间偏差也大,因此偏差轨道和按标称值飞行的标准轨道之间偏差大,传统的摄动制导难以满足对卫星高入轨精度的要求。针对固体运载火箭的上述特点,本文提出具有工程意义的闭路制导方法。实现闭路制导的关键之一是需要速度的求解。本文根据运载火箭的实时飞行状态和卫星轨道元素之间的关系推导出简单实用的需要速度,并应用于发射近圆轨道卫星的小型固体运载火箭的闭路制导控制中。经过数学仿真验证,证明本文中的方法在各种干扰下均具有较高的精度。