遥感图像云检测方法综述

光学遥感图像中云层会对地面信息进行不同程度的遮挡,造成了地表观测信息的模糊和缺失,极大地影响遥感图像的成像质量。因此,对遥感图像中云层覆盖的检测和评估是进一步分析和利用遥感图像信息的基础和关键。通过充分的调研和对比总结,梳理了20世纪90年代以来,国内外基于遥感图像的云检测方法的发展趋势和代表性工作。将基于遥感图像的云检测方法分为三类：基于光谱阈值的方法、基于经典机器学习的方法以及基于深度学习的方法。总结了当前国内外云检测公开数据集,并对比了部分代表性工作的云检测精度。此外,简要梳理了与云检测相关的云雾(霾)检测、云雪检测、云阴影检测以及云去除等方法。对当前云检测相关工作中存在的问题和未来的发展趋势进行了分析和展望。     

预警机跑道形巡航探测效能研究

对预警机跑道形巡航时的探测效能问题进行了研究。基于SEA的基本原理,阐述了预警机跑道形巡航探测效能问题,给出了跑道形巡航想定和预警机在此作战环境和作战样式下的MOP集合,重点研究了MOP的系统映射模型,建立了在相对坐标系下分析预警机探测概率和平均覆盖时间的模型,指出了对MOP的使命映射研究方法,采用SEA方法对预警机跑道形巡航探测效能进行了分析。算例说明了模型的正确性。     

基于博弈论模型的多机协同对抗多目标任务决策方法

根据多机协同对抗多目标的空战特征,以敌我双方可能的相互攻击组合方式作为策略集,由敌我双方对抗态势分析定量结果确定支付函数,建立完全信息静态博弈模型.通过求解博弈模型的混合策略纳什均衡解,并结合一定作战经验,形成任务决策方法.以无人作战飞机编队对抗敌地对空防御系统为例,对本文所研究的任务决策方法进行了验算.     

基于多智能体深度强化学习的多星观测任务分配方法

为应对多星环境中复杂多约束条件下的任务分配场景,提出一种多星自主决策观测任务分配算法,该算法采用基于集中式训练、分布式执行的多智能体深度强化学习算法。通过这种方式训练后的卫星智能体,即使在没有中心决策节点或通信受限的情况下,仍具有一定的自主协同能力及独立实现多星观测任务的高效分配能力。     

PEM水电解技术在航天上的应用现状与发展趋势

介绍了质子交换膜(PEM)水电解技术的特点及其在国内外航天领域的应用现状,在分析空间任务的发展趋势,以及能源、动力、环境控制与生命保障系统需求变化的基础上,认为在未来载人航天任务中,能源、动力、生保物质互用的解决方法是摆脱依赖地面支持、实现自主和可持续保障的最优途径,并指出了PEM水电解技术作为实现这一技术途径的关键环节所面临的挑战。     

Statistical study of energetic electrons in Jupiter’s inner magnetosphere by Juno/JEDI

The Juno spacecraft made the first in-situ observations of energetic particles in the polar region of Jupiter’s magnetosphere. After Jupiter Orbit Insertion (JOI) in July 2016, data from ~20 Juno perijoves (PJs) obtained by Juno/JEDI are accumulated, providing an excellent opportunity to study the long term spatio-temporal distribution of energetic particles in Jupiter’s radiation belt. We transform Juno’s position from a Cartesian to a magnetic coordinate system by tracing magnetic field lines based on a fourth order Runge-Kutta method. Then the fluxes of energetic electrons from PJ1 to PJ14 sorted by different locations in magnetic coordinate space and the data are well organized by the L-shell parameter. The variation of electron flux increases with L-shell. The deviation (the ratio of the 75th percentile to the 25th percentile) of 0.51 MeV electron flux varies from a factor of 1.23 near L = 9.5 to 27.57 near L = 15.5. However, the mean flux decreases by about one order of magnitude in the same region. The electron spectra at larger L-shells are softer than that at smaller L-shells. On the other hand, the electron flux decreases more rapidly with increased L-shell when the location is off the equator. Along an L-shell, the electron flux decrease at first and then increase again from equator to mid-latitude region. In addition, we compare the statistical results with the widely used GIRE2 model. JEDI data correspond well with the GIRE2 model when the L-shell is > 14.75. GIRE2 underestimate the electron flux for L-shell smaller than 13.25. These results of this analysis are applicable to estimate the effects of the radiation environment in Jupiter’s magnetosphere.     

运载火箭推力故障下在线计算轻量化任务重构方法

为了避免运载火箭推力下降故障引起发射任务失败,基于径向基神经网络,提出了一种在线计算轻量化的任务重构方法,可快速在线计算最优救援轨道对应飞行轨迹(最优轨迹)的近似解.在离线部分,结合凸优化与自适应配点法产生"故障状态-最优轨迹"数据集.数据集被用来训练径向基神经网络,建立轨迹决策模型来构建故障状态到最优轨迹的动力学关系...     

Improvement of the GRACE star camera data based on the revision of the combination method

The new release of the sensor and instrument data (Level-1B release 02) of the Gravity Recovery and Climate Experiment (GRACE) had a substantial impact on the improvement of the overall accuracy of the gravity field models. This has implied that improvements on the sensor data level can still significantly contribute to arriving closer to the GRACE baseline accuracy. The recent analysis of the GRACE star camera data (SCA1B RL02) revealed their unexpectedly higher noise. As the star camera (SCA) data are essential for the processing of the K-band ranging data and the accelerometer data, thorough investigation of the data set was needed. We fully reexamined the SCA data processing from Level-1A to Level-1B with focus on the combination method of the data delivered by the two SCA heads. In the first step, we produced and compared our own combined attitude solution by applying two different combination methods on the SCA Level-1A data. The first method introduces the information about the anisotropic accuracy of the star camera measurement in terms of a weighing matrix. This method was applied in the official processing as well. The alternative method merges only the well determined SCA boresight directions. This method was implemented on the GRACE SCA data for the first time. Both methods were expected to provide optimal solution characteristic by the full accuracy about all three axes, which was confirmed. In the second step, we analyzed the differences between the official SCA1B RL02 data generated by the Jet Propulsion Laboratory (JPL) and our solution. SCA1B RL02 contains systematically higher noise of about a factor 3–4. The data analysis revealed that the reason is the incorrect implementation of algorithms in the JPL processing routines. After correct implementation of the combination method, significant improvement within the whole spectrum was achieved. Based on these results, the official reprocessing of the SCA data is suggested, as the SCA attitude data are one of the key observations needed for the gravity field recovery.     

多任务使命平台上电子设备发展趋势研究

通过对侦察、对抗和打击一体化系统在现代战争中的地位与作用的介绍,分析了多任务使命平台上各种电子设备之间的冲突,提出了在多任务使命平台上综合电子设备的发展趋势,在此基础上得出几点启示.