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光帆航天器发展现状及“突破摄星”计划关键技术
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作者 李志杰 果琳丽 +2 位作者 黄江川 张小琳 张柏楠 《航天器工程》 北大核心 2016年第5期111-118,共8页
光帆航天器可以借助太阳光,也可以从地基或空基能量站发出激光对其加速,与传统的化学推进相比,光帆推进技术可以使航天器获得较大的加速度,从而进行较远空间目的地的探测活动。文章对国外光帆航天器的发展现状及主要技术指标进行了调研... 光帆航天器可以借助太阳光,也可以从地基或空基能量站发出激光对其加速,与传统的化学推进相比,光帆推进技术可以使航天器获得较大的加速度,从而进行较远空间目的地的探测活动。文章对国外光帆航天器的发展现状及主要技术指标进行了调研,重点介绍了"突破摄星"计划(Breakthrough Starshot)概况,并对其重要系统组成及计划工程实施过程进行了详细分析。最后对"突破摄星"计划中可能涉及到的关键技术进行了梳理,包括地面大型激光阵列技术、芯片星器件集成技术、光帆轻质材料技术、光帆姿态控制技术以及深空激光通信技术。以上研究内容可为我国发展光帆航天器技术提供参考。 展开更多
关键词 光帆 航天器 “突破摄星”计划 关键技术
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行摄无疆之藏地追星
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作者 任萃毅 蔡承博 《天文爱好者》 2016年第5期68-71,共4页
去年夏天的一次朋友聚会上,我再次向蔡承博提出了那个筹谋已久却迟迟没有实施的摄星计划--去雪域高原摄星,在我一番鼓唇摇舌下蔡终于毅然决然地做出决定--2016年春节期间进藏!
关键词 雪域高原 春节期间 朋友聚会 摄星
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Effects of salinity on growth and feeding of juvenile Starry flounder (Platichthys stellatus) 被引量:2
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作者 尤宏争 张升利 +1 位作者 郭忠宝 姜志强 《Marine Science Bulletin》 CAS 2013年第1期66-75,共10页
The survival rate, feeding, growth of juvenile Starry flounder were studied at different salinities. The results showed that when the fish was directly translated from salinity of 32 to 0 and more than 0, the survival... The survival rate, feeding, growth of juvenile Starry flounder were studied at different salinities. The results showed that when the fish was directly translated from salinity of 32 to 0 and more than 0, the survival rate was 100% in 96 hours. If the fish was acclimatized, it was still 100% in 42 days. The fish at the salinity of 0 - 16 grew faster than others; feeding rate varied as salinity changed, and the highest one was at salinity of 32 and the lowest one was at the salinity of 16. As to feed conversion efficiency, the highest one was at the salinity of 16, and the lowest one was at the salinity of 24. There were no significant differences among the treatments (P&gt;0.05). It was found that low salinity benefited for recovering albinism. 展开更多
关键词 Starry flounder SALINITY survival rate FEEDING GROWTH
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Small Target Extraction Based on Independent Component Analysis for Hyperspectral Imagery 被引量:3
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作者 LU Wei YU Xuchu 《Geo-Spatial Information Science》 2006年第2期103-107,共5页
A small target detection approach based on independent component analysis for hyperspectral data is put forward. In this algorithm, firstly the fast independent component analysis(FICA) is used to collect target infor... A small target detection approach based on independent component analysis for hyperspectral data is put forward. In this algorithm, firstly the fast independent component analysis(FICA) is used to collect target information hided in high-dimensional data and projects them into low-dimensional space.Secondly, the feature images are selected with kurtosis .At last, small targets are extracted with histogram image segmentation which has been labeled by skewness. 展开更多
关键词 fast independent component analysis SKEWNESS KURTOSIS target extraction
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Approximate Approaches to Geometric Corrections of High Resolution Satellite Imagery 被引量:3
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作者 SHIWenzhong AhmedShaker 《Geo-Spatial Information Science》 2004年第1期24-30,共7页
The exploitation of different non-rigorous mathematical models as opposed to the satellite rigorous models is discussed for geometric corrections and topographic/thematic maps pro duction of high-resolution satellite ... The exploitation of different non-rigorous mathematical models as opposed to the satellite rigorous models is discussed for geometric corrections and topographic/thematic maps pro duction of high-resolution satellite imagery (HRSI). Furthermore, this paper fo cuses on the effects of the number of GCPs and the terrain elevation difference within the area covered by the images on the obtained ground points accuracy. Fr om the research, it is obviously found that non-rigorous orientation and triang ulation models can be used successfully in most cases for 2D rectification and 3 D ground points determination without a camera model or the satellite ephemeris data. In addition, the accuracy up to the sub-pixel level in plane and about on e pixel in elevation can be achieved with a modest number of GCPs. 展开更多
关键词 remote sensing RECTIFICATION POLYNOMIALS HIGH-RESOLUTION
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The effects of spectrograph slit modes on the accuracy of stellar radial velocity measurement and atmospheric parameter estimation 被引量:2
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作者 WANG FengFei ZHANG HaoTong +3 位作者 LUO ALi BAI ZhongRui DU Bing ZHAO YongHeng 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2013年第10期1833-1839,共7页
Spectrograph slit is conventionally used to enhance the spectral resolution ~md manage how much light can be allowed to enter spectrograph. The narrow slit provides a higher resolution but sacrifices efficiency of spe... Spectrograph slit is conventionally used to enhance the spectral resolution ~md manage how much light can be allowed to enter spectrograph. The narrow slit provides a higher resolution but sacrifices efficiency of spectrograph and results in a low signal to noise ratio (S/N) spectra product. We take GuoShouJing telescope as an example and carry out a series of experiments to study how its 2/3 slit mode affects the precision of stellar radial velocity measurement and atmosphere parameters estimate. By transforming the resolution and adding a Gaussian White Noise to the extremely high quality spectra from the Sloan Digital Sky Survey, we generate synthetic stellar spectra of various brightness with different S/Ns. Comparing the measurements on these noise added spectra with the original high quality ones, we summarize the influences of the 2/3 slit mode on the meas- urement accuracy of stellar radial velocity and atmospheric parameters. 展开更多
关键词 slit mode resolution stellar radial velocity atmosphere parameters SPECTROGRAPH
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