某类任务的无人作战飞机航路规划

讨论了对于包含了既是威胁又有价值的节点的任务模型,无人作战飞机航路规划问题解决的思路和关键环节,并构建了数学模型,然后应用A*启发算法求解各个目标点的最优航路,并依据作战指挥人员对作战方案的总体把握给出的权衡因子,计算每个目标点取得的费效比,确定满足一定条件下最先攻击目标.实例仿真表明该方法可以有效地解决这类任务的航路规划问题.     

嫦娥一号卫星的制导、导航与控制

嫦娥一号卫星是中国首颗月球卫星。卫星制导、导航与控制(GNC)任务复杂多变,对系统实时性、可靠性和精度要求较高。文章介绍嫦娥一号卫星GNC系统组成、控制方法、系统特点和典型飞行结果。     

嫦娥一号卫星热控设计中热管的应用及验证

为克服由于月球热环境的特殊性给热控设计带来的困难,尤其是卫星度过月食的极端状态条件,首次采用了舱外两舱热耦合热管、相变材料热管技术,为最终嫦娥一号卫星热控状态满足总体的技术要求发挥了关键作用。由于两舱热耦合技术的采用,两舱的热能量得到了相互补偿,因此减少了整星散热面,减少了热补偿功率需求,提高了月食结束时蓄电池的温度,使热控技术方案成为相对优化的方案。文章对热管技术在嫦娥一号卫星热控设计中的应用进行了总结,并给出了热分析及热平衡。     

基于GJB289A标准的通用总线数据分析

基于GJB289A总线标准协议,采用先进的数据分析解算算法,对总线记录仪记录的总线数据文件进行分析,系统支持多粒度、多种方式的数据分析和显示功能。系统与ICD采用自动对接,针对不同型号提供统一的分析接口;采用C/S模式的系统结构,既满足多用户同时使用,又满足不同型号同时在线分析,真正实现了系统的通用性。     

CAS-1 lunar soil simulant

Lunar soil simulant is a geochemical reproduction of lunar regolith, and is needed for lunar science and engineering researches. This paper describes a new lunar soil simulant, CAS-1, prepared by the Chinese Academy of Sciences, to support lunar orbiter, soft-landing mission and sample return missions of China’s Lunar Exploration Program, which is scheduled for 2004–2020. Such simulants should match the samples returned from the Moon, all collected from the lunar regolith rather than outcrops. The average mineral and chemical composition of lunar soil sample returned from the Apollo 14 mission, which landed on the Fra Mauro Formation, is chosen as the model for the CAS-1 simulant. Source material for this simulant was a low-Ti basaltic scoria dated at 1600 years from the late Quaternary volcanic area in the Changbai Mountains of northeast China. The main minerals of this rock are pyroxene, olivine, and minor plagioclase, and about 20–40% modal glass. The scoria was analyzed by XRF and found to be chemically similar to Apollo 14 lunar sample 14163. It was crushed in an impact mill with a resulting median particle size 85.9 μm, similar to Apollo soils. Bulk density, shear resistance, complex permittivity, and reflectance spectra were also similar to Apollo 14 soil. We conclude that CAS-1 is an ideal lunar soil simulant for science and engineering research of future lunar exploration program.     

激光焊接ZL114A/5A06 异种铝合金接头组织及性能

采用激光焊接ZL114A/5A06异种铝合金,通过参数优化以获得性能优良的焊接接头,利用光学显微镜(OM)、拉力试验机、高温疲劳试验机、SEM和EDS对接头的显微组织、力学性能和拉伸断口进行了研究。结果表明:焊缝中心区的金相组织为等轴晶;接头焊后不经热处理,抗拉强度可达到265 MPa,为母材强度的80%以上,并有很好的抗疲劳性能;断口分析显示断裂位置在ZL114A母材一侧的熔合线附近;在保证焊透的前提下,激光功率越小,晶粒越细小,接头强度越高。对框架蒙皮结构铝合金贮箱产品试验件进行了焊接,试验件达到了产品各项性能指标要求。     

FY-3A卫星与NOOA系列卫星高能带电粒子实测结果的比较

FY-3A卫星是运行于830 km高度的太阳同步轨道气象卫星,其搭载的空间环境监测器可观测3～300 MeV的高能质子和0.15～5.70 MeV的高能电子.FY-3A卫星在轨工作期间,太阳活动处于由谷年向峰年过渡期,空间环境非常平静,探测结果显示3～300 MeV的高能质子分布主要集中在南大西洋辐射带异常区,0.15～5.70 MeV的高能电子分布区域除南大西洋异常区外,还分布在南北两极高纬区域.FY-3A与NOAA卫星测量结果反映出带电粒子强度及分布区域随投掷角变化的空间各向异性特征.本文在充分考虑了带电粒子时间、空间分布差异以及比对探测器之间自身设计差异的前提下,经过归一化处理后,首次对两颗卫星同期探测结果进行相关性分析,验证了两颗卫星相同时空条件下高能带电粒子通量分布的一致性;说明FY-3A空间环境监测器不仅具备空间带电粒子辐射监测能力,且探测结果有效可靠,可用作辐射带环境数据源的组成部分,为发展新的模型,深入研究辐射带高能粒子的分布、起源和传输等提供新的观测依据.     

Fast solar radiation pressure modelling with ray tracing and multiple reflections

Physics based SRP (Solar Radiation Pressure) models using ray tracing methods are powerful tools when modelling the forces on complex real world space vehicles. Currently high resolution (1?mm) ray tracing with secondary intersections is done on high performance computers at UCL (University College London). This study introduces the BVH (Bounding Volume Hierarchy) into the ray tracing approach for physics based SRP modelling and makes it possible to run high resolution analysis on personal computers. The ray tracer is both general and efficient enough to cope with the complex shape of satellites and multiple reflections (three or more, with no upper limit). In this study, the traditional ray tracing technique is introduced in the first place and then the BVH is integrated into the ray tracing. Four aspects of the ray tracer were tested for investigating the performance including runtime, accuracy, the effects of multiple reflections and the effects of pixel array resolution.Test results in runtime on GPS IIR and Galileo IOV (In Orbit Validation) satellites show that the BVH can make the force model computation 30–50 times faster. The ray tracer has an absolute accuracy of several nanonewtons by comparing the test results for spheres and planes with the analytical computations. The multiple reflection effects are investigated both in the intersection number and acceleration on GPS IIR, Galileo IOV and Sentinel-1 spacecraft. Considering the number of intersections, the 3rd reflection can capture $99.12\%\text{,}99.14\%$, and $91.34\%$ of the total reflections for GPS IIR, Galileo IOV satellite bus and the Sentinel-1 spacecraft respectively. In terms of the multiple reflection effects on the acceleration, the secondary reflection effect for Galileo IOV satellite and Sentinel-1 can reach 0.2?$\text{nm}/{\text{s}}^2$ and 0.4?$\text{nm}/{\text{s}}^2$ respectively. The error percentage in the accelerations magnitude results show that the 3rd reflection should be considered in order to make it less than $0.035\%$. The pixel array resolution tests show that the dimensions of the components have to be considered when choosing the spacing of the pixel in order not to miss some components of the satellite in ray tracing. This paper presents the first systematic and quantitative study of the secondary and higher order intersection effects. It shows conclusively the effect is non-negligible for certain classes of misson.     

Operation and Application of A, B Satellites for Environment and Disaster Monitoring and Forecasting

Environment and disaster monitoring and forecasting small satellite constellation A and B satellites (HJ-1-A, B) are called "environment and disaster reduction satellites A and B' for short. The constellation adopts a 10:30 LT sun-synchronous circular orbit, with orbit altitude of 649 km. HJ-1-A and HJ-1-B are distributed with a phase difference of 180o in the same orbital plane, so as to enhance the time resolution of earth observation. The satellites have orbit maintenance capability, the lifetime is 3 years. Both satellites adopt CAST968 platforms. Two wide-coverage multispectral CCD cameras with resolution 30 m and width 700 km, a super-spectral imager with resolution 100 m and width 50 km as well as a data transmission subsystem of 120 Mbit/s are deployed on HJ-1-A, which also carries Ka communication testing equipment of Thailand. HJ-1-B has two wide-coverage multispectral CCD cameras (the same as satellite A), one infrared camera with resolution 150 m and width 720 km and a data transmission subsystem of 60 Mbit/s. The coverage period of the wide-coverage multispectral CCD camera is 48 hours. The revisit period of super-spectral imager is 96 hours and the coverage period of infrared camera is 96 hours.      

月球车全局路径规划中的A＊算法改进

考虑月球车全局路径规划的应用要求,针对传统A＊算法搜索速度慢和返回路径不够优化的缺点,对算法流程进行改进,减少其时间和空间复杂度,提高其搜索速度,并对返回路径进行优化,有效地缩短了路径。对于存在凹形障碍的地图,采用后退一尝试的方法解决规划失败的问题,并在一次搜索的基础上使用二次搜索策略来实现规划路径的优化,使之绕过凹形障碍趋向目标,从而达到输出最短路径的目的。