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961.
海况对水下运载器吊放回收的影响 总被引:1,自引:1,他引:1
本文将水下运载器,吊索和母船看作是一个由弹簧连接的单自由度系统,通过对系统进行分析和研究,建立了水下被吊物体在吊索带动下,由吊臂端点运动引起的运动响应的物理模型、数学方程,并编制了各项参数可调的计算机程序以求解水下物体的运动轨迹。运用此程序,对影响参数作系列变化后进行了运动响应计算,并绘制成运动响应随这些参数变化的曲线,为水下吊放回收系统的设计提供了依据 相似文献
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Cudnik Brian M. Dunham David W. Palmer David M. Cook Anthony Venable Roger Gural Peter S. 《Earth, Moon, and Planets》2003,93(3):145-161
The occurrence and visibility of meteoroid impacts on the moon as seen from the earth were little more than speculation prior to November 1999. The best evidence of present-day impact activity came from the seismic experiments left on the Moon during the Apollo era. Past systematic attempts at earth-based observations to document lunar impacts revealed nothing conclusive. However, during the Leonid storms of 1999 and 2001, lunar impact events were for the first time confirmed by multiple independent observers. A total of 15 meteoritic impact flash events have been verified during these storms, with an additional 12 unconfirmed but likely events awaiting confirmation. Estimates of the mass of these meteoroids range from less than one gram for the faintest flashes to more than 10 kg for the brightest observed flash. The fraction of visible light to total energy produced by these events, a quantity known as luminous efficiency, averages about 0.001 for the established events. The confirmation of lunar meteoritic events on the Moon opens a new avenue in lunar and planetary research, one which could help bridge the gap between atmospheric sampling of the smallest components of meteoroid streams and interplanetary debris to the larger scale objects accessible to ground-based telescopes. 相似文献
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The availability of Very High Resolution (VHR) optical sensors and a growing image archive that is frequently updated, allows the use of change detection in post-disaster recovery and monitoring for robust and rapid results. The proposed semi-automated GIS object-based method uses readily available pre-disaster GIS data and adds existing knowledge into the processing to enhance change detection. It also allows targeting specific types of changes pertaining to similar man-made objects such as buildings and critical facilities. The change detection method is based on pre/post normalized index, gradient of intensity, texture and edge similarity filters within the object and a set of training data. More emphasis is put on the building edges to capture the structural damage in quantifying change after disaster. Once the change is quantified, based on training data, the method can be used automatically to detect change in order to observe recovery over time in potentially large areas. Analysis over time can also contribute to obtaining a full picture of the recovery and development after disaster, thereby giving managers a better understanding of productive management and recovery practices. The recovery and monitoring can be analyzed using the index in zones extending from to epicentre of disaster or administrative boundaries over time. 相似文献
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一种能适应月相变化的月球图像中心提取算法 总被引:1,自引:0,他引:1
月球是夜间最亮的天体,测月导航可在云雾天气下有效弥补传统天文导航在夜间只能观测恒星的不足,扩大天文导航的可用范围。为实现测月导航,提出了一种能适应不同月相变化的月球敏感器图像月球中心提取算法。利用Sobel-Zernike矩算子对图像进行边缘检测,利用基于圆形性检测的搜索算法筛选月球边缘点并以此提取月球中心。经半物理仿真实验解算,该算法能够针对不同月相图像有效提取月球中心,中心提取的内符合平均精度为0.16像素,外符合平均精度为2.86″。由于在月球上观测地球也有"地相"变化,该算法同样适用于月球车地球敏感器图像中心提取。 相似文献
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针对UCXP-wa相机影像的特点,本文介绍了利用外方位元素恢复立体模型的方法。分析影响空三加密成果质量的因素,并结合工作实际,总结作业中的注意事项,对常见错误进行解决分析。 相似文献
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The fictitious compress recovery approach is introduced, which could be applied to the establishment of the Rungerarup theorem, the determination of the Bjerhammar's fictitious gravity anomaly, the solution of the "downward con- tinuation" problem of the gravity field, the confirmation of the convergence of the spherical harmonic expansion series of the Earth's potential field, and the gravity field determination in three cases: gravitational potential case, gravitation case, and gravitational gradient case. Several tests using simulation experiments show that the fictitious compress recovery approach shows promise in physical geodesy applications. 相似文献