利用光变曲线估计猎鹰九号火箭末级的旋转状态研究     

苏向泽  汤儒峰  李荣旺  李语强 《天文研究与技术》2021,(2):203-212

光度观测是地基观测空间目标的主要手段之一,利用光度信息能够估计空间目标的相关特征信息。为了更好地了解空间目标的旋转状态,选取具有代表性的猎鹰九号火箭末级作为研究对象,由其光变信息研究旋转状态。首先利用云南天文台1.2 m光学望远镜获取猎鹰九号火箭末级的光度数据,再对目标星等进行斜距归一化,得到目标光变信息并分析目标星等随时间变化的曲线,估计大致的旋转周期,再由相位离散最小化方法计算会合周期。根据太阳、目标和测站之间的位置关系、惯性主轴指向、旋转轴指向、初始相位等因素,采用姿态旋转矩阵计算理论星等,利用最小二乘原则确定惯性主轴方向及初相角度、旋转轴指向。最后给出了猎鹰九号火箭末级的旋转周期、会合周期以及旋转轴指向等参数,为后续开展其他空间目标光度信息研究提供参考。  相似文献   

The Basic Shape Classification of Space Debris with Light Curves     

LU Yao  ZHAO Chang-yin 《Chinese Astronomy and Astrophysics》2021,45(2):190-208

We study the machine learning method for classifying the basic shape of space debris in both simulated and observed data experiments, where light curves are used as the input features. In the dataset for training and testing, simulated light curves are derived from four types of debris within different shapes and materials. Observed light curves are extracted from Mini-Mega TORTORA (MMT) database which is a publicly accessible source of space object photometric records. The experiments employ the deep convolutional neural network, make comparisons with other machine learning algorithms, and the results show CNN (Convolutional Neural Network) is better. In simulational experiments, both types of cylinder can be distinguished perfectly, and two other types of satellite have around 90% probability to be classified. Rockets and defunct satellites can achieve 99% success rate in binary classification, but in further sub-classes classifications, the rate becomes relatively lower.  相似文献   

Gentrification as space domestication. The High Line Art case     

Pier Luigi Sacco  Maria Tartari  Guido Ferilli  Giorgio Tavano Blessi 《Urban geography》2019,40(4):529-554

In this paper, we critically examine the role of artistic locational choices and practices in the context of gentrification processes in urban renewal contexts. We characterize gentrification as a form of domestication of space, and explore the extent to which artistic choices and practices relate to such process with reference to the deontological dilemma of legitimization within the art system vs. responsible empowerment of vulnerable local constituencies. We illustrate our argument with an analysis of the High Line Art project, and show how this can be considered as a textbook example of art-driven space domestication leading to brutal forms of gentrification. We comment on the threat that this provides to the social credibility of artistic practices as an agency of responsible social change.  相似文献   

海洋功能区划与海洋生态红线关系探讨          下载免费PDF全文

高月鑫  曾江宁  黄伟  陈全震  寿鹿  徐晓群 《海洋开发与管理》2018,35(1):33-39

海洋生态红线制度是我国"五位一体"文明建设的具体要求。为进一步在自然科学与人文科学的联结点上探求深入开展生态红线工作的可能性,文章对比了实施多年的海洋功能区划与历史新阶段提出的海洋生态保护红线的概念和内涵,剖析了两者之间的区别与联系,指出海洋功能区划与海洋生态红线区划在法律地位和管控制度等方面具有一致性,在划分目标、空间管理及划分方法上具有差异性,海洋功能区划以"使用"为主,海洋生态红线以"保护"引领。在此基础上,建议未来海洋生态红线工作的开展可从海洋功能区划借鉴经验,建立完善的管控评估制度,确立生态保护红线的优先地位,处理好海洋功能区划与海洋生态红线区划的关系。同时,海洋生态红线区划应以维持海洋生态系统结构稳定和提高海洋生态系统服务功能为目标,将区域资源环境承载力评估作为一项参考指标,限制低承载区的开发利用,保证海洋生态环境健康可持续发展。  相似文献   

新04号泉溶解气氢气异常特征分析   总被引：1，自引：0，他引：1  

李新勇  朱成英  李艳萍  聂晓红 《内陆地震》2014,28(3):286-290

选取乌鲁木齐周围100 km范围内MS4地震和300 km范围内MS≥5地震,分析新04号泉氢气资料。结果显示,新04号泉对乌鲁木齐周围100 km范围内4级地震无明显震兆异常,对300 km范围内MS≥5地震对应情况较好,对应率为80%。  相似文献   

一种基于天基的瞬变电磁高分辨探测小尺度太空碎片的方法          下载免费PDF全文

李文翰  李贺  鲁凯亮  崔洪亮 《地球物理学报》2018,61(12):5066-5076

目前，太空碎片的天基探测方法一般是激光雷达法.由于激光雷达的辐射频率一般为可见光或红外波段，在分辨厘米量级的太空碎片时具有一定的优势.但激光雷达在探测时也面临一些客观问题：即（1）难以捕捉快速移动的太空碎片；（2）对目标体穿透能力低；（3）外层空间的强干扰环境对激光雷达的不良影响等.这些问题在一定程度上限制了激光雷达在太空碎片探测方面的应用.本文针对太空碎片体积小、预警距离远和强干扰环境等特点，提出使用高性能瞬变电磁辐射源对远距离、小尺度的太空碎片进行探测.通过三维矢量有限元方法，分析了利用高性能瞬变电磁辐射源的优点，对比不同瞬变电磁辐射源的幅频特性，从发射机理上证明高性能瞬变电磁辐射源在辐射能力与频率带宽方面都优于传统瞬变电磁辐射源.并通过调整脉冲宽度，得到最适合探测本文太空碎片模型的辐射脉冲.最后通过电场分布图和多测道图对太空碎片的明显电场分异结果，证实了高性能瞬变电磁辐射源在探测远距离、小尺度太空碎片方面的有效性.  相似文献   

Low-energy Lunar Trajectories with Lunar Flybystwo     

Wei Bing-wei  Li Yin-shan 《Chinese Astronomy and Astrophysics》2018,42(4):575-593

The low-energy lunar trajectories with lunar flybys are investigated based on the Sun-Earth-Moon bicircular problem (BCP). The characteristics of the distribution of trajectories in the phase space are summarized. Using the invariant manifolds in the BCP system, the low-energy lunar trajectories with lunar flybys are sought. Then, take time as an augmented dimension in the phase space of a nonautonomous system, we present the state space map and reveal the distribution of these lunar trajectories in the phase space. Consequently, we find that the low-energy lunar trajectories exist as families, and that the every moment in the Sun-Earth-Moon synodic period can be the departure date. Finally, we analyse the velocity increment, transfer duration, and system energy for the different trajectory families, and obtain the velocity-impulse optimal family and the transfer-duration optimal family, respectively.  相似文献   

无控制DEM表面差异探测研究   总被引：1，自引：1，他引：0  

张同刚  岑敏仪  吴兴华 《测绘科学》2006,31(3):36-38

本文提出了一个新的无控制DEM差异探测算法。它可以将不同时期获取的DEM纳入到统一坐标系中,这样就可以根据匹配后的DEM来定量探测地表变化情况。该方法通过差分模型考虑了观测量的数值及其相互关系。与目前差异探测能力最强的LMS-LZD方法相比,新方法具有更好的差异能力和更高的匹配精度。普歪沟泥石流沟多时相DEM差异探测实例验证了新方法的优越性。  相似文献   

Multi-band Solar Full-disk Extreme Ultraviolet Imager     

PENG Ji-long  FENG Tao-jun  SHI En-tao  LI Lin  YU Qian  ZHANG Kai  NIE Xiang-yu  MA Zi-liang 《Chinese Astronomy and Astrophysics》2019,43(3):444-456

Solar Extreme Ultraviolet (EUV) imaging observation is an important measure for the researches of solar activities and coronal plasma physics. But the traditional EUV imager and spectrograph can hardly achieve simultaneously the high spectral resolution and wide field-of-view of solar imaging. This paper has designed a new type of solar EUV multi-band imager, by adopting a kind of slitless grating and grazing incidence structure, it can realize the solar full-disk imaging of high spectral and spatial resolution. The field-of-view of the imager can be as broad as 47′. The spectral resolution is 2×10^?3nm per pixel, and the spatial resolution is 1.4′ per pixel. The temporal resolution of the solar full-disk is better than 60 s. The analysis of the solar full-disk spectral image and system response shows that the imager can observe the morphological evolutions of various solar activities, and can provide more comprehensive data for the researches of solar physics and space weather forecast.  相似文献   

Time-frequency decomposition of seismic signals via quantum swarm evolutionary matching pursuit     

Amir Semnani  Liang Wang  Mehdi Ostadhassan  Majid Nabi-Bidhendi  Babak Nadjar Araabi 《Geophysical Prospecting》2019,67(7):1701-1719

Matching pursuit belongs to the category of spectral decomposition approaches that use a pre-defined discrete wavelet dictionary in order to decompose a signal adaptively. Although disengaged from windowing issues, matching point demands high computational costs as extraction of all local structure of signal requires a large size dictionary. Thus in order to find the best match wavelet, it is required to search the whole space. To reduce the computational cost of greedy matching pursuit, two artificial intelligence methods, (1) quantum inspired evolutionary algorithm and (2) particle swarm optimization, are introduced for two successive steps: (a) initial estimation and (b) optimization of wavelet parameters. We call this algorithm quantum swarm evolutionary matching pursuit. Quantum swarm evolutionary matching pursuit starts with a small colony of population at which each individual, is potentially a transformed form of a time-frequency atom. To attain maximum pursuit of the potential candidate wavelets with the residual, the colony members are adjusted in an evolutionary way. In addition, the quantum computing concepts such as quantum bit, quantum gate, and superposition of states are introduced into the method. The algorithm parameters such as social and cognitive learning factors, population size and global migration period are optimized using seismic signals. In applying matching pursuit to geophysical data, typically complex trace attributes are used for initial estimation of wavelet parameters, however, in this study it was shown that using complex trace attributes are sensitive to noisy data and would have lower rate of convergence. The algorithm performance over noisy signals, using non-orthogonal dictionaries are investigated and compared with other methods such as orthogonal matching pursuit. The results illustrate that quantum swarm evolutionary matching pursuit has the least sensitivity to noise and higher rate of convergence. Finally, the algorithm is applied to both modelled seismograms and real data for detection of low frequency anomalies to validate the findings.  相似文献