Using the Global Navigation Satellite System and satellite altimetry for combined Global Ionosphere Maps

For deriving global maps of the Total Electron Content (TEC) from space geodetic techniques usually observations from the Global Navigation Satellite System (GNSS) are taken. However, the GNSS stations are inhomogeneously distributed, with large gaps particularly over the sea surface.     

论高校学报的交流与利用

阐述了高校学报交流的意义、重要性和必要性。提出了交流学报应纳入图书馆的统一管理系统。进而实现学报的宣传服务、检索服务、咨询服务和多元化的信息服务。     

惯导系统产品装配多余物控制方法

阐述了控制惯导系统中多余物的重要性,分析了在操作过程中惯导系统多余物产生的条件和因素,根据多年的惯导系统生产经验,总结了控制多余物的实际操作要求,最后叙述了对多余物常用检查方法及使用MORET-300活动多余物检测设备的方法。     

An environmentally sensitive dynamic human model for LSS robustness studies with the V-HAB simulation

The development of efficient and safe Life Support Systems is one of the key drivers of the Global Solar System Exploration efforts. For each task performed by Life Support Systems (LSS) a great multitude of sub-system concepts exist and the challenge is to find the optimal combination of sub-systems for a given mission scenario. On a sub-system level the Equivalent Systems Mass (ESM) trade study approach is well suited to effectively compare sub-system options. On a system level in addition to ESM data time dependent sub-system performances within an overall system must be addressed. Criteria such as system stability, controllability and effectiveness must be considered in order to be able to assess the dynamic robustness of systems designed to the averages. In an effort to establish a dynamic simulation environment for this type of LSS optimizations the “Virtual Habitat” tool (V-HAB) is being developed at the Technical University of Munich (TUM). This paper introduces the most important part of the Virtual Habitat simulation, which is the human model.     

制导误差分离中环境函数矩阵的精确计算方法

主要讨论了制导工具误差分离中环境函数矩阵的精确计算问题。环境函数矩阵的计算精度对制导工具误差分离精度有重要影响。提出了2种精确计算环境函数矩阵的方法,用六自由度弹道仿真程序验证了2种方法的有效性。     

基于预测滤波器的GPS姿态估计

采用预测滤波器,利用全球定位系统的双差相位观测量实现载体姿态估计。该方法对初值的选取具有鲁棒性,可以在天线和可见星较少的情况下快速收敛到姿态精确解。仿真结果显示,该方法的姿态估计结果可以与基于非线性最小二乘的姿态估计结果相比拟,且受初值的影响小;采用双差相位测量比采用单差相位测量可以得到更佳的姿态估计效果;当使用三基线的天线阵时,在飞行机动较大的情况下采用近似正交布局的天线结构可以更好地估计姿态。     

基于软件锁相环的电机速度控制系统

随着电力电子、微电子技术和控制技术的发展,一些场合对电机调速系统性能的要求越来越高,而锁相调速控制在稳速精度方面有其独特的优势。文章在改进的数字锁相环基础上,提出了软件锁相环电机速度控制系统,利用高性能微处理器实现了软件锁相环。     

基于凸优化技术的多目标鲁棒滤波组合导航方法

Kalman滤波在组合导航中的应用已很广泛,但是,在系统不确定情况下,误差出现发散,精度下降,采用的基于Riccati方程的H∞滤波技术对系统噪声的不确定性则具有一定的鲁棒性,但性能参数选取仅能凭经验而无系统的方法,给工程实践带来一定困难.根据现代控制理论最优控制理论思想,使用凸优化技术设计鲁棒混合H2/H∞滤波器融合高精度的GPS和CNS量测信息,解决系统不确定性问题,通过在惯性/卫星/天文组合系统中的半物理数据仿真进一步对混合H2/H∞滤波和H∞滤波算法进行了比较.仿真结果表明,真实器件噪声情况下,鲁棒混合H2/H∞滤波算法明显具有良好的精度.     

遥测系统再认识

遥测系统是闭环系统,不是惯称的开环系统。与控制系统相比,遥测系统具有三大特点:测量信息源的不确定性;反馈通道与主通道的相关性;系统误差主要源于主通道。研究并获取系统传递函数是系统设计的重要内容,而机理分析和系统辨识正是适合该需求的有效措施。     

Changes in operational procedures to improve spaceflight experiments in plant biology in the European Modular Cultivation System

The microgravity environment aboard orbiting spacecraft has provided a unique laboratory to explore topics in basic plant biology as well as applied research on the use of plants in bioregenerative life support systems. Our group has utilized the European Modular Cultivation System (EMCS) aboard the International Space Station (ISS) to study plant growth, development, tropisms, and gene expression in a series of spaceflight experiments. The most current project performed on the ISS was termed Seedling Growth-1 (SG-1) which builds on the previous TROPI (for tropisms) experiments performed in 2006 and 2010. Major technical and operational changes in SG-1 (launched in March 2013) compared to the TROPI experiments include: (1) improvements in lighting conditions within the EMCS to optimize the environment for phototropism studies, (2) the use of infrared illumination to provide high-quality images of the seedlings, (3) modifications in procedures used in flight to improve the focus and overall quality of the images, and (4) changes in the atmospheric conditions in the EMCS incubator. In SG-1, a novel red-light-based phototropism in roots and hypocotyls of seedlings that was noted in TROPI was confirmed and now can be more precisely characterized based on the improvements in procedures. The lessons learned from sequential experiments in the TROPI hardware provide insights to other researchers developing space experiments in plant biology.