多维系统测量的误差分析计算

多维系统测量参数众多,系统误差分析比较复杂。本文归纳给出多维系统测量误差分析计算方法措施,并给出算例。     

流量预测下智能寻优门限值的AOS帧生成算法

针对AOS空间通信系统的自适应帧生成算法帧生成时间门限值需要人工设置问题,提出一种流量预测下智能寻优门限值的AOS帧生成算法.该算法使用小波神经网络对ON/OFF模型产生的自相似流量进行预测,根据预测流量计算复用效率和平均包时延,使用人工鱼群算法对建立的综合评价函数进行智能寻优,从而得到帧生成算法的最佳门限值.该算法可...     

Finite-time relative orbit-attitude tracking control for multi-spacecraft with collision avoidance and changing network topologies

This paper addresses the relative position tracking and attitude synchronization control problem for spacecraft formation flying (SFF). Based on the derived relative coupled six-degree-of-freedom dynamics, a robust adaptive finite-time fast terminal sliding mode controller is proposed to achieve the desired formation in the presence of model uncertainties and external disturbances. It is shown that the designed controller is effective for changing information exchange topology making it robust to node failure. Then, the artificial potential function method is employed to generate collision avoidance schemes to modify the controller such that inter-agent collision avoidance can be ensured during the formation maneuver, which is critical for practical missions. The stability of the overall closed-loop system is proved by using Lyapunov theory. Finally, numerical examples for a given SFF scenario are presented to illustrate the performance of the controller.     

Analysis of BDS-3 distributed autonomous navigation based on BeiDou system simulation platform

Satellite autonomous navigation is an important function of the BeiDou-3 navigation System (BDS-3). Satellite autonomous navigation means that the navigation satellite uses long-term forecast ephemeris and Inter-Satellite Link (ISL) measurements to determinate its own spatial position and time reference without the support of the ground Operation and Control System (OCS) for a long time to ensure that the navigation system can normally maintain the time and space reference. This paper aims to analyze the feasibility of distributed autonomous navigation algorithms. For the first time, a ground parallel autonomous navigation test system (GPANTS) is built. The performance of distributed autonomous navigation is then analyzed using the two-way ISL ranging of BDS-3 satellites. First, the BDS simulation platform and the GPANTS are introduced. Then, the basic principles of distributed satellite autonomous orbit determination and time synchronization based on ISL measurements are summarized. Preliminary evaluation of the performance of the BDS-3 constellation autonomous navigation service under ideal conditions through simulation data. Then the performance of autonomous navigation for 22 BeiDou-3 satellites using ISL measurements is evaluated. The results show that when satellites operate autonomously for 50 days without the support of any ground station, the User Range Error (URE) of autonomous orbit determination is better than 3 m, and the time synchronization accuracy is better than 4 ns.     

空间光学遥感器光机结构材料应用情况及展望

介绍了空间光学遥感器的技术特点,综述了近年来空间光学遥感器光机结构材料的应用状况,对空间光学遥感器的光机结构材料发展趋势进行了展望。     

随遇接入卫星应急任务响应技术研究

面对在轨卫星当前对突发事件、灾难应急等突发性、短暂性的使用需求,传统空间系统应用存在任务规划提前制定、难以临时变更的缺点,卫星系统无法快速对该类突发事件进行资源保障.因此迫切需要构建高效、即时的空间任务执行体系.研究了随遇接入卫星应急任务响应技术,该技术可统筹任务执行过程中涉及的各条链路及各类资源,全面改善任务执行即时性.     

Experimental research of air-throttling ignition for a scramjet at Ma 6.5

An experimental investigation on ignition characteristics with air-throttling in an ethylene-fueled scramjet under flight Ma 6.5 conditions was conducted.The dynamic process of air-throttling ignition was explored systematically.The influences of throttling parameters,i.e.,throttling mass rate and duration,were investigated.When the throttling mass rate was 45% of the inflow mass rate,ambient ethylene could be ignited reliably.The delay time from ignition to throttling was about 45–55 ms.There was a threshold of throttling duration under a certain throttling mass rate.It was shorter than 100 ms when the throttling mass rate was 45%.While a 45%throttling mass rate would make the shock train propagate upstream to the isolator entry in about10–15 ms,four lower throttling mass rates were tested,including 30%,25%,20%,and 10%.All of these throttling mass rates could ignite ethylene.However,combustion performances varied with them.A higher throttling mass rate made more ethylene combust and produced higher wall pressure.Through these experiments,some aspects of the relationships between ignition,flame stabilization,combustion efficiency,and air-throttling parameters were brought to light.These results could also be a benchmark for CFD validation.     

基于职业能力培养的模拟电子技术课程教学改革实践

《模拟电子技术》课程是电子技术专业的一门核心主干课程,主要培养学生常用电子元器件的识别与检测,电子电路的分析、制作与测试等职业能力。通过对学生职业能力的培养,有力促进了教学模式、教学内容、教学方法、教学手段等诸多方面的改革,承载了职业院校的人才培养目标,取得了比较明显的教学成效。     

空间近程高速相对运动方程的状态转移矩阵

分析了空间近程高速相对运动的特点,建立了描述近程高速相对运动的线性微分方程组,并给出了状态转移矩阵与解析解。仿真结果表明:对于HEO-GEO近程高速相对运动,所建方程的相对距离计算误差仅为16 cm,不足Hill方程计算误差的15%。所给出的状态转移矩阵对于实现空间目标拦截等任务的实时高精度相对导航和制导算法具有一定的应用价值。     

月球主要构造特征：嫦娥一号月球影像初步研究

月球在31亿年前已基本停止地质活动,从而保留了其形成初期的信息．这些信息对于认识月球、地球乃至太阳系的形成演化具有重要意义．在已有研究成果的基础上,结合嫦娥一号探月卫星CCD影像数据,从月海穹窿、撞击坑、月岭、断裂、月坑链、月溪及月谷等方面介绍了月球主要构造形式的地质特征、形貌特征及遥感影像特征,对其成因以及所隐含的地质意义进行了分析．结果表明,嫦娥一号CCD影像信息丰富,影像清晰,利用其CCD影像数据进一步研究月球的构造现象是可行的．