Zenith Pass Problem of Inter-satellite Linkage Antenna Based on Program Guidance Method

While adopting an elevation-over-azimuth architecture by an inter-satellite linkage antenna of a user satellite, a zenith pass problem always occurs when the antenna is tracing the tracking and data relay satellite （TDRS）. This paper deals with this problem by way of, firstly, introducing movement laws of the inter-satellite linkage to predict the movement of the user satellite antenna followed by analyzing the potential pass moment and the actual one of the zenith pass in detail. A number of specific orbit altitudes for the user satellite that can remove the blindness zone are obtained. Finally, on the base of the predicted results from the movement laws of the inter-satellite linkage, the zenith pass tracing strategies for the user satellite antenna are designed under the program guidance using a trajectory preprocessor. Simulations have confirmed the reasonability and feasibility of the strategies in dealing with the zenith pass problem.     

Leakage performance of floating ring seal in cold/hot state for aero-engine

Rotating experimental investigations were carried out to study the oil sealing capability of two different floating ring seals in cold/hot state for aero-engine. High-speed Floating Ring Seal(HFRS) is a seal with the inner diameter of 83.72 mm and maximum speed of 38000 r/min, and Low-speed Floating Ring Seal(LFRS) is another seal with the inner diameter of 40.01 mm and maximum speed of 18000 r/min. In hot state, sealing air with the temperature of 371 K and oil with the temperature of 343 K was employed to model the working conditions of an aero-engine. Comparisons between floating ring seal and labyrinth seal were done to inspect the leakage performance.More attention was paid to the critical pressure ratio where the oil leakage began. Results show that the critical pressure ratio in cold state is obviously larger than that in hot state for both seals. An underlying sealing mechanism for floating ring seal is clarified by the fluid film, which closely associates with the dimensionless parameter of clearance over rotating diameter(2 c/Dr). Another fantastic phenomenon is that the leakage coefficient in hot state, not the leakage magnitude, is unexpectedly larger than that in cold state. Overall, the leakage performance of the floating ring seal is better than the labyrinth seal.     

热流限制下的最优气动力辅助变轨

以变轨能量消耗最小为优化目标，应用极大值原理研究了飞行过程受热流限制和升力系统约束下的气动力辅助共面变轨问题，飞行过程成分第一自由弧段，约束弧段，第二自由弧段三个部分，讨论了升力系数的最优表达式，分析了飞行过程中两种约束的相互作用，给出了约束弧起始位置的角点条件和终端的横截条件下，对不同的初值选取方法讨论了三种计算策略，并给出了数值算例。     

长征四号乙／丙运载火箭多星发射技术现状与展望

介绍了长征四号乙／丙（CZ-4B／4C）运载火箭的多星发射技术。给出了整流罩Ф900mm的一箭双星、一箭三星的发射统计与串联发射构型、正在研制的更大包络的双星发射构型,以及并联发射构型。介绍了CZ-4B／4C运载火箭后续多星发射和搭载发射的构型、连接解锁装置和分离程序。     

萤火一号火星探测器有效载荷数管软件控制技术

对萤火一号(YH 1)火星探测器有效载荷数据管理软件控制技术进行了研究.介绍了软件的组成.给出了控制需求与约束.软件综合利用立即指令队列、事件表、宏指令和指令状态机等机制,实现了对光学成像仪、掩星接收机、磁强计、等离子体探测包4种有效载荷,以及测控数传分系统的控制,可满足YH-1火星探测器的要求.     

时差定位卫星簇的时域关联干扰方法研究

时差定位卫星簇对地表的辐射源存在很大威胁.为保护目标辐射源,在分析时差定位卫星簇TDOA脉冲配对的原理的基础上,提出一种新的主动干扰方法.即通过控制干扰脉冲与辐射源脉冲之间的时域关联关系,达到欺骗时差定位卫星的TDOA估计.仿真计算表明,适当的脉冲发射时间和脉冲宽度的同频干扰源对辐射源位置信息的保护具有可行性和有效性.     

批产航天器设备布局研究

分析了批产航天器小批量、多状态的特点,描述了这些特点给航天器研制带来的设备布局设计难题;提出了以舱板布局作为基本配置单元进行设备布局的方案,通过特殊设备识别、配置矩阵制定、配置状态转化、配置状态编码和配置组合等步骤,实现批产航天器设备布局状态控制;最后,结合产品数据管理系统,说明了导航卫星设备布局方案。     

模块航天器间激光无线能量传输系统方案设想

模块化航天器是未来航天器发展的重要方向,模块航天器之间的能量传输是实现模块化功能应用的关键技术。文章针对模块化航天器系统能量分配需求,对无线激光能量传输技术进行了研究。阐述了无线激光能量传输系统的功能组成,建立了系统框架模型,分析了系统的关键技术,并对系统各组成模块进行了初步设计。在此基础上对激光传能系统进行了试验验证,获得了理想的光电转换效率。文章的研究成果可为我国模块航天器的发展提供技术支持。     

水凝物对THz波辐射的衰减研究

文章基于水凝物粒子尺寸与THz波长的大小关系,分别利用Rayleigh近似、Mie理论以及几何光学方法计算了降雨和云雾引起THz波辐射的散射衰减。比较了不同强度的降雨和不同能见度、含水量的云雾对THz波的散射衰减。结果表明,随着频率的增大,THz波段雨衰减先增大后减小;在整个THz波段,含水量较小或能见度较低的云雾的衰减随频率的增大而单调增加,含水量较大或能见度较大的云雾的衰减随频率先增大后减小;在THz波段云雾衰减随能见度的减小和含水量的增加而增大,温度对THz波段的云雾衰减影响不大,在整个THz波段并不存在明显的规律。在THz波频率高端云雾影响较降雨要严重的多。     

一种星-箭连接动态界面力的深度学习反演方法

针对于星-箭连接动态界面力无法通过力传感器直接测量,且典型时域动载反演方法难以准确计算界面力的时域变化等难点,提出了基于长短时记忆(LSTM)神经网络的星-箭界面力深度学习反演方法。首先通过卫星地面测试试验得到数据依据,以卫星主体结构的加速度测量数据为输入层,以星-箭界面力测量数据为输出层,利用LSTM神经网络建立输入和输出间的反演映射关系模型,实现卫星在发射过程中较高精度的界面力反演。进而,设计并开展了某典型卫星结构的正弦扫频和随机振动实验,测试LSTM界面力反演方法的可行性。结果分析可知,所提出的基于LSTM深度学习反演方法能够精确地获得动态界面力时程数据,两项性能指标均优于目前典型的载荷反演方法。