卫星氢镍蓄电池电解液在轨回流特性仿真

氢镍蓄电池电解液在轨流动特性是影响其工作性能和使用寿命的重要因素,对蓄电池设计与优化具有重要意义。针对高轨通信卫星使用的80Ah氢镍蓄电池,建立了电解液流动运动的三维仿真模型,采用计算流体动力学（CFD）数值仿真方法,对氢镍蓄电池单体内的电解液在轨微重力条件下的流动特性和分布特点进行了仿真研究。通过对比分析不同边界条件下的仿真结果,提出了在蓄电池极堆与壳体两端之间增加电解液流动路径可以提高电解液回流速度,并改进卫星氢镍蓄电池在轨工作性能,研究结果可为卫星蓄电池和电源系统设计提供参考。     

航星座自主运行平行系统的轨道计算方法

构建一个能够与实际卫星导航系统长期保持时空一致的平行系统,可为导航星座自主运行提供一个监视与评估平台。针对建设该平行系统所需的高逼真轨道计算问题,引入平行系统理论的思想,在分析历史精密轨道的基础上,提出高精度轨道计算与预报方法。该方法以不断更新的精密轨道作为输入,利用PID增量式算法或时变加权法进行数据平滑,使得轨道计算结果始终与实际系统保持高度一致性。试验结果表明,该方法可使卫星轨道计算的结果与实际卫星轨道长期保持在分米量级。     

A balloon-borne very long baseline interferometry experiment in the stratosphere: Systems design and developments

The balloon-borne very long baseline interferometry (VLBI) experiment is a technical feasibility study for performing radio interferometry in the stratosphere. The flight model has been developed. A balloon-borne VLBI station will be launched to establish interferometric fringes with ground-based VLBI stations distributed over the Japanese islands at an observing frequency of approximately 20?GHz as the first step. This paper describes the system design and development of a series of observing instruments and bus systems. In addition to the advantages of avoiding the atmospheric effects of absorption and fluctuation in high frequency radio observation, the mobility of a station can improve the sampling coverage (“uv-coverage”) by increasing the number of baselines by the number of ground-based counterparts for each observation day. This benefit cannot be obtained with conventional arrays that solely comprise ground-based stations. The balloon-borne VLBI can contribute to a future progress of research fields such as black holes by direct imaging.     

北斗首颗备份卫星性能初步分析

主要从卫星钟差预报、轨道测定精度、伪距波动情况等角度分析了I6卫星与北斗卫星导航系统（BDS）其他现役倾斜地球同步轨道（IGSO）卫星的异同,并从位置精度因子（PDOP）和格网可用性评估了I6卫星入网对BDS的贡献。利用星地双向时频传递设备观测的星地钟差数据,评估了I6卫星星载原子钟的预报性能,结果表明,I6卫星发播的卫星钟参数外推5h预报误差的均方根误差（RMS）为232ns,外推1h预报误差的RMS为073ns,与现役IGSO卫星钟差预报水平相当;对多星联合精密定轨结果分析表明,与北斗现役I3卫星相比,姿态控制方式优化后的I6卫星在地影期间的轨道精度并未发生明显衰减,克服了现有北斗二号卫星在地影期间轨道精度下降,从而影响北斗服务的连续性、可用性问题;利用大口径抛物面天线采集到的数据对I6卫星的伪距波动进行了分析,结果表明I6卫星单个观测弧段内其伪距波动峰峰差约为1m,与其他IGSO卫星一致;进行PDOP仿真计算,结果表明I6卫星的加入使得喀什地区的PDOP最大值由1282下降为726,PDOP大于6的时段所占百分比由2911%下降为1721%;对格网电离层产品实施解算,结果表明I6卫星的加入使得6个电离层格网点的可用度提升至95%以上。     

Multipath mitigation method based on Gaussian mixture model in RF relative measurement

Radio Frequency (RF) technology represents a high-precision relative navigation solution that has significant potential for application to earth-orbiting satellites. In precision applications, multipath errors dominate the total error because observables, which are used to estimate carrier-phase integer ambiguity, are not always subject to a Gaussian distribution when dual-frequency ambiguity estimation methods are used in the presence of multipath. As it has been shown that ranging observables obey a Gaussian mixture distribution, this study proposes improvements to the accuracy of estimation based on multipath mitigation founded on the Gaussian mixture model. To this end, such a model is created for integer ambiguity resolution in the presence of multipath, using which the theoretical error in dual-frequency ambiguity estimation is derived. Expectation Maximization (EM), which aids dual-frequency ambiguity estimation, is subsequently proposed to reduce the effect of multipath errors. Finally, two experimental scenarios are implemented to test the performance of the proposed method. The results show that EM-aided dual-frequency ambiguity estimation reduces the range error to approximately 20% in comparison with simple dual-frequency ambiguity estimation. Therefore the proposed technique is effective for multipath mitigation in RF relative measurement.     

东方红三号卫星的机械太阳阵和通信天线

介绍了中德合作研制、生产东方红三号机械太阳阵和通信天线的有关技术和项目的进展情况。机械太阳阵的设计是在经过自行验证的技术基础上进行的,有了这些经验,加上计算机设计优化,能够满足苛刻的质量和刚度要求。通信天线的主要特点是收发共用和全极化复用。它是通过两套7喇叭馈源阵照射极化敏感反射器实现的。天线电性能和结构性能均满足技术要求。     

卫星研制中的接口数据管理

在卫星研制工作中可采用11种接口数据单加强设备的接口数据管理工作。它们是:机械特性,设备示意图,热特性,热特性示意图,电源功率,接口电特性,电气方块图,接插件表,接插件接点分配表,遥测表,遥控指令表。它们包含了可以全面反映设备接口特性的各项数据。使用它们可以进行严格的状态管理并保证接口数据协调工作的质量。文内介绍了这些数据单的具体内容以及使用中的问题。     

卫星空间外热流轨道参数ψ_0,Ω_0和ω_0计算

文章给出了卫星热分析空间外热流计算中所需要的轨道参数太阳黄经、升交点赤经和近地点幅角的初值φ_0、Ω_0、ω_0 的计算公式。其精确度满足卫星热分析要求。     

光学太阳反射器卫星搭载数据的非线性拟合

采用线性回归和优选法相结合的方法较好地解决了形如函数ｙ＝ａ［１－ｅｘｐ（－ｂｘ）］的曲线拟合问题。通过对中国光学太阳反射器卫星搭载数据的拟合分析,得出了光学太阳反射器的光学性能的空间衰变的经验表达式,并对光学太阳反射器的长期空间稳定性进行了预测。     

星载数据系统的结构

星载数据系统通过全星的计算机联网,建立统一数据管理,支持系统重组。文章探讨了星载数据系统结构的选择原则;并提出并行计算机系统的几种结构（如网格形和交叉开关网络）比目前使用的总线型结构更适合星载数据系统。