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Double lunar swing-by orbits revisited

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Science China(Physics,Mechanics & Astronomy) 2014年第4期57卷 784-790页

作者： hou xiyun LIU Lin School of Astronomy and Space Science Nanjing University Institute of Space Environment and Astrodynamics Nanjing University

The double lunar swing-by orbits are a special kind of orbits in the Earth-Moon *** orbits repeatedly pass through the vicinity of the Moon and change their shapes due to the Moon’s *** the synodic frame of the circular restricted three-body problem consisting of the Earth and the Moon,these orbits are periodic,with two close approaches to the Moon in every orbit *** this paper,these orbits are *** is found that these orbits belong to the symmetric horseshoe periodic families which bifurcate from the planar Lyapunov family around the collinear libration point ***,the double lunar swing-by orbits have k=i+j loops,where i is the number of the inner loops and j is the number of outer *** genealogy of these orbits with different i and j is studied in this *** is,how these double lunar swing-by orbits are organized in the symmetric horseshoe periodic families is *** addition,the 2n lunar swing-by orbits(n≥2)with 2n close approaches to the Moon in one orbit period are also studied.

关键词： double lunar swing-by orbit restricted three-body problem periodic orbit

Two-maneuver indirect contingency return from a low lunar orbit

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Chinese Journal of Aeronautics 2023年第8期36卷 115-127页

作者： Yunfei LI Xiaosheng XIN xiyun hou School of Astronomy and Space Science Nanjing UniversityNanjing 210023China Key Laboratory of Modern Astronomy and Astrophysics(Nanjing University) Ministry of EducationNanjing 210023China Beijing Institute of Tracking and Telecommunication Technology Beijing 100094China

The problem of contingency return from the low lunar orbit is studied.A novel twomaneuver indirect return strategy is *** effectively using the Earth’s gravity to change the orbital plane of the transfer orbit,the second maneuver in the well-known three-maneuver return strategy can be removed,so the total delta-v is *** with the singlemaneuver direct return,our strategy has the advantage in that the re-entry epoch for the minimum delta-v cost can be advanced in time,with a minimum delta-v value similar to that of the direct *** most obvious difference between our strategy and the traditional single-or multiplemaneuver strategies is that the complete transfer orbit is a patch between a two-body conic orbit and a three-body orbit instead of two conic *** strategy can serve as a useful option for contingency return from a low lunar orbit,especially when the delta-v constraint is stringent for a direct return and the contingency epoch is far away from the return window.

关键词： Moon Lowlunarorbit Contingencyreturn Third-body maneuver Gravityassist

A note on the full two-body problem and related restricted full three-body problem

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Astrodynamics 2018年第1期2卷 39-52页

作者： xiyun hou Xiaosheng Xin School of Astronomy and Space Science Nanjing UniversityNanjing 210023China Institute of Astrodynamics and Space Environment Nanjing UniversityNanjing 210093China

Truncating at the second order of the mutual potential between two rigid bodies,time-explicit rst order solutions to the rotations and the orbital motion of the two bodies in the planar full two-body problem(F2BP)are *** on this analytical solution,equations of motion(EOMs)for the related restricted full three-body problem are *** the case of the synchronous or double synchronous states for the full two-body problem,EOMs for the related restricted full three-body problem(RF3BP)are also *** last,one example-the"collinear libration point"in the binary asteroid system-is given.

关键词： full two-body problem(F2BP) restricted full three-body problem(RF3BP) binary asteroid collinear libration point

Initial orbit determination of some cislunar orbits based on short-arc optical observations

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Astrodynamics 2024年第3期8卷 455-469页

作者： xiyun hou Bosheng Li Xin Liu Haowen Cheng Ming Shen Peng Wang Xiaosheng Xin School of Astronomy and Space Science Nanjing UniversityNanjing210023China National Astronomical Observatories Beijing100012China China Spacesat Co.Ltd. Beijing100037China Beijing Institute of Tracking and Telecommunication Technology Beijing100094China

Ground-and space-based optical observation is an efficient way to catalog objects in the cislunar *** orbit determination based on optical data is still an open problem for cislunar *** motion of these objects usually follows the law of three bodies instead of the two-body one,so current algorithms based on the two-body relation should be ***,due to the long duration of most cislunar objects,optical observations of even hours can cover only a small fraction of one orbit,making the initial orbit determination of these objects a typical too-short-arc problem,which is difficult.A way to address this problem is to use the admissible *** this study,an efficient algorithm constrained by the admissible region is *** is easy to implement because it uses only simple *** efficiency is proven by comparing it with that of one traditional initial orbit determination algorithm.

关键词： orbit determination cislunar too-short-arc(TSA) admissible region

Message from the Guest Editors of the Special Issue on Precise Orbit Determination

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Astrodynamics 2024年第3期8卷 323-323页

作者： xiyun hou Jay W.McMahon School of Astronomy and Space Science Nanjing UniversityNanjingChina Ann and H.J.Smead Department of Aerospace Engineering Sciences the University of Colorado BoulderBoulderColorado 80309USA

Dear authors and readers,Orbit determination is an old topic in celestial mechanics and *** originates from the need to determine the position and speed of natural or artificial objects in space through ground-station measurements,along with the need to estimate parameters involved in dynamics and *** has been the key to many important space applications.

关键词： dynamics observations Orbit

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基于模板匹配的莫尔条纹倾角计算

红外与激光工程 2015年第9期44卷 2825-2830页

作者：何帆白剑侯西云浙江大学现代光学仪器国家重点实验室浙江杭州310027

提出了一种基于模板匹配的亚像素处理方法,可以精确计算出在大口径长焦距测量过程中出现的莫尔条纹的角度。基于泰伯效应和莫尔条纹干涉的长焦距测量方法是一种高精度的焦距测量方法。理论分析表明:这种测量方法的精度很大程度上依赖于... 详细信息

提出了一种基于模板匹配的亚像素处理方法,可以精确计算出在大口径长焦距测量过程中出现的莫尔条纹的角度。基于泰伯效应和莫尔条纹干涉的长焦距测量方法是一种高精度的焦距测量方法。理论分析表明:这种测量方法的精度很大程度上依赖于莫尔条纹角度的精度。之前是通过迭代算法在亚像素域中寻找莫尔条纹频谱的最大值点来计算莫尔条纹的角度。然而实验过程中得到的莫尔条纹往往会出现不同程度的弯曲和畸形,这会大大影响这种方法的测量精度。从改进测算角度算法这个角度出发,针对傅里叶变换后的频谱图,基于模板匹配的思想,对各种莫尔条纹进行二维正态分布拟合,找出频谱点精确坐标,从而精确测量莫尔条纹角度。理论分析和软件仿真表明:这种方法具有高精度、高稳定等优点,能有效提高长焦距的测量精度。

关键词：长焦距测量莫尔条纹亚像素模板匹配

Trajectory Design and Optimization for LEO Satellites in Formation to Observe GEO Satellites’ Beams

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International Journal of Astronomy and Astrophysics 2018年第4期8卷 368-385页

作者： Yi Lu Yu Sun xiyun hou Yunhe Meng State Key Laboratory of Astronautic Dynamics China Xi’an Satellite Control Center Xi’an China School of Astronomy & Space Science Nanjing University Nanjing China Tianqin Research Center for Gravitational Physics Sun Yat-sen University Zhuhai China

This paper presents the methods and results for the trajectory design and optimization for the low earth orbit (LEO) satellites in formation to observe the geostationary orbit (GEO) satellites’ beams. The background of the trajectory design mission is the 9th China Trajectory Optimization Competition (CTOC9). The formation is designed according to the observation demands. The flying sequence is determined by a reference satellite using a proposed improved ephemeris matching method (IEMM). The formation is changed, maintained and transferred following the reference satellite employing a multi-impulse control method (MICM). Then the total observation value is computed by propagating the orbits of the satellites according to the sequence and transfer strategies. Based on the above methods, we have obtained a fourth prize in the CTOC9. The proposed methods are not only fit for this competition, but can also be used to fulfill the trajectory design missions for similar multi-object explorations.

关键词： Trajectory Design Global Optimization Formation Flying Flying Sequence Formation Maintaining

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单光学系统全景环带立体成像技术

红外与激光工程 2012年第12期41卷 3342-3348页

作者：白剑黄治侯西云浙江大学现代光学仪器国家重点实验室浙江杭州310027

提出一种基于全景环带透镜（PAL）的新型全景环带立体成像系统。该系统含有两组同轴放置并成像于同一个传感器上的PAL单元，其成像圆为两内外相接的圆环。物体经过两个PAL单元分别成像于两个环中，通过三角测量法比较相同物体的像在两... 详细信息

提出一种基于全景环带透镜（PAL）的新型全景环带立体成像系统。该系统含有两组同轴放置并成像于同一个传感器上的PAL单元，其成像圆为两内外相接的圆环。物体经过两个PAL单元分别成像于两个环中，通过三角测量法比较相同物体的像在两个圆环中的位置差异，可提取出物体的距离信息。这种新型的光学系统的中央盲区被其中一个PAL单元所利用，成为这个PAL单元的成像圆，增加了传感器像素的利用率。系统可提取立体信息的视场角为（60°-105°）×360°；提取深度信息的分辨率约为在500min范围内区域高于1 line／cm；为了使系统适用于较暗的光照环境下，其脒约为3。具体介绍了其设计过程，提取深度信息的方法和精度的分析过程以及实物和照片。

关键词：全景PAL光学系统立体成像光学设计

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激光光刻中的超分辨现象研究

光学学报 1999年第11期19卷 1512-1517页

作者：沈亦兵杨国光侯西云浙江大学现代光学仪器国家重点实验室杭州310027

激光光刻是加工微光学及二元光学掩模的主要手段。光刻的最细线宽对所加工的二元微器件性能起决定作用。本文导出了会聚的高斯光束用于激光光刻时在光刻胶内的光场近似分布形式，由此可判断出能光刻线条的分辨力。若入射高斯光束受到... 详细信息

激光光刻是加工微光学及二元光学掩模的主要手段。光刻的最细线宽对所加工的二元微器件性能起决定作用。本文导出了会聚的高斯光束用于激光光刻时在光刻胶内的光场近似分布形式，由此可判断出能光刻线条的分辨力。若入射高斯光束受到振幅或相位调制时，胶层内的光强分布将发生变化，从而影响曝光线条的线宽和质量。计算看出：当入射光中心环受到遮拦时，可以得到超过光刻物镜极限分辨的线条宽度（０．６ μｍ），但此时对曝光能量控制要求很高。在激光直接写入系统上的曝光试验结果与理论计算相符。

关键词：二元光学激光直写微光刻超分辨光刻