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771.
针对地面兴趣点不沿星下点轨迹的动态非沿轨迹成像问题,设计一种结合扩展状态观测器的非奇异快速终端滑模控制器。首先根据非沿轨迹成像模型的需求推导卫星姿态参考轨迹。其次,根据由误差四元数描述的跟踪误差运动模型设计了非奇异快速终端滑模控制律。考虑到干扰抑制,引入了扩展状态观测器来观测系统的总扰动,从而降低滑模控制律中的切换增益,削弱系统抖振。然后再用模糊自适应系统对切换项进行在线逼近,柔化控制信号,进一步减振。最后,对具有干扰和参数不确定的姿态控制系统进行了数值仿真,结果表明该方法收敛速度快,控制精度高。 相似文献
772.
FY-3 is the second generation polar-orbiting meteorological satellite of China. The first satellite named FY-3A of this series was launched on 27 May 2008. The first operational satellite named FY-3C of this series was launched on 23 September, 2013. The new generation satellites are to provide three-dimensional, quantitative, multi-spectral global remote sensing data under all weather conditions, which will greatly help the operational numerical weather prediction, global climate change research, climate diagnostics and prediction, and natural disaster monitoring. They will also provide help for many other fields such as agriculture, forestry, oceanography and hydrology. With the abovementioned capability, the FY-3 satellites can make valuable contributions to improving weather forecasts, global natural-disaster and environmental monitoring. 相似文献
773.
Prabhunath Prasad Shantanu Rastogi R.P. Singh 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
This paper reports a study of spatial and temporal variations of columnar averaged concentration of CO2 and CH4 over India using SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) and Greenhouse gas Observing SATellite (GOSAT) data. Comparison of these data with the global view National Oceanic and Atmospheric Administration (NOAA) land data and also location specific flask data is made. The temporal variation in column averaged global CO2 is similar to that over India and it is also similar to the NOAA surface flask data and global view. The variation in NOAA surface CH4 is location dependent and its global view appears to vary seasonally in opposite phase with the column averaged CH4 values from satellites, reflecting the limited comparability of surface and column averaged data. Over India the CO2 maximum is in May and minimum in August/September while for CH4 the maximum is in September and minimum in February/March. The seasonal variation of CH4 over India is correlated with the eastern coastal rice cultivation. 相似文献
774.
Haiying Liu Zhiming Chen Weisong Ye Huinan Wang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
Carrier phase ambiguity resolution of Global Navigation Satellite System (GNSS) is a key technology for high-precision navigation and positioning, and it is a challenge for applications which require both high accuracy and high integrity. This paper proposes efficient ambiguity resolution methods based on integrity restriction using Fixed Failure rate Ratio Test (FF-RT) and Doubly Non-central F-distribution Ratio Test (DNF-RT), and derives the related processing models and numerical algorithms compared with the traditional Ratio Test (RT) method. Firstly, the integer ambiguity resolution and validation procedures, especially the Least squares AMBiguity Decorrelation Adjustment (LAMBDA) estimation and RT validation are analyzed. Then the quality evaluation using success rate, the FF-RT method using Integer Aperture (IA) estimation and the NDF-RT method are proposed. Lastly, the simulation and analysis for LAMBDA using RT, FF-RT and DNF-RT methods are performed. Simulation results show that in case of unbiased scenario FF-RT and DNF-RT have similar performances, which are significantly better than RT. In case of biased scenario it is difficult for FF-RT to predict the biased success rate thus it should not be used for bias detection, while DNF-RT can detect biases in most cases except for the biases are approximate or equal to integer, which has the important benefit for early detection of potential threat to the position solution. 相似文献
775.
Zhong-Ping Zhang Hai-Feng Zhang Wan-Zhen Chen Pu Li Wen-Dong Meng Yuan-Ming Wang Jie Wang Wei Hu Fu-Min Yang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
Beidou is the regional satellite navigation system in China, consisting of three kinds of orbiting satellites, MEO, GEO and IGSO, with the orbital altitudes of 21500–36000 km. For improving the accuracy of satellites orbit determination, calibrating microwave measuring techniques and providing better navigation service, all Beidou satellites are equipped with laser retro-reflector arrays (LRAs) to implement high precision laser ranging. The paper presents the design of LRAs for Beidou navigation satellites and the method of inclined installation of LRAs for GEO satellites to increase the effective reflective areas for the regional ground stations. By using the SLR system, the observations for Beidou satellites demonstrated a precision of centimeters. The performances of these LRAs on Beidou satellites are very excellent. 相似文献
776.
A.S. Arya R.P. RajasekharAmitabh B. Gopala KrishnaAjai A.S. Kiran Kumar 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
Domes, an analog of the terrestrial shield volcanoes are one of the important volcanic features found on the lunar surface. Such volcanic features are windows to better understanding of the contrasting natures of lunar volcanism, giving an insight into the source and the nature of the basaltic magmas. Marius Hills Complex is one of the most important regions in the entire lunar surface for having a complex setting of volcanic constructs with an abundant number of volcanic features like domes, cones and rilles. As a part of initiation of the study of Marius Hills volcanism, an effusive dome located to the south of Rima Galilaei, near the contact of Imbrian and Eratosthenian geological units is taken for the present study. Inferring from the Terrain Mapping Camera-Digital Elevation Model (TMC-DEM), the morphometric parameters are estimated (350 m in height, 9.62 km in diameter), and accordingly the rheological parameters are also estimated. As the signatures of multiphase eruption are not clear geomorphologically and also in topography, the dome is assumed to evolved in monogenetic eruption. The causative dike parameters of the dome are estimated, which gives upper bounds of true values of the parameters. The estimated feeder dike length (150 km) and width (233 m) implies that the source region is lying most probably in the mantle portion of moon. The crater size frequency distribution (CSFD) is applied to determine the age of the particular dome and also the surrounding mare surface so as to better construct a stratigraphic correlation. It is found that dome belongs to oldest age unit of Marius Hills region while the surrounding units are relatively younger. Using Chandrayaan-I Moon Mineralogy Mapper (M3) data, the surface composition for the study area is also analysed. Thus, the morphometry, rheology, dike parameters, age determination and mineralogy are found to be in good agreement with results of the earlier studies. Such a study, covering all the domes and other volcanic features in Marius Hills using high resolution data sets will provide a clear and better understanding of the volcanic history of the region and the Oceanus Procellarum Basin as well. In such a study, the application potential of high resolution Chandrayaan-I TMC image and its DEM generated from the stereo data has been useful. 相似文献
777.
针对卫星编队飞行相对位置协同控制问题,基于编队卫星相对运动非线性动力学方程和一致性理论设计了两种自适应协同控制器。首先,在卫星质量不确定和星间信息交互存在通信时延的条件下,设计了一种全状态反馈自适应协同控制器,并证明了该控制策略对空间摄动力的鲁棒性。其次,进一步考虑速度信息不可测的条件下,采用滤波器设计了一种无速度反馈的自适应协同控制器。最后,以编队构型重构为例对两种自适应协同控制器进行了仿真校验。仿真结果表明:两种自适应协同控制器均可有效应用于卫星编队飞行相对位置的协同控制,能够保证编队卫星对各自期望轨迹跟踪的同时暂态保持编队构型的稳定,具有较高的控制精度。 相似文献
778.
779.
针对遥感影像融合过程中存在的光谱失真,提出了一种基于光谱响应函数(SRF)的ZY-3卫星影像融合算法,该算法通过研究亮度分量的模拟方法和空间细节注入方法,改进了传统的IHS算法。采用融合前后典型地物光谱曲线对比和无需参考图像的质量评价指标(QNR)两种方式对融合结果进行评价,发现该算法的光谱信息保持在89.94%,QNR值达0.75以上。结果表明,相对于其它IHS改进融合算法,基于ZY-3卫星传感器SRF的改进IHS融合算法无论在光谱信息保持还是空间信息增强方面都具有优势。 相似文献
780.