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浏览/检索结果: 共4条，第1-4条 帮助 限定条件 发表日期：2010     已选(0)清除 条数/页：5101520253035404550556065707580859095100   排序方式：请选择作者升序作者降序题名升序题名降序发表日期升序发表日期降序提交时间升序提交时间降序 从《点石斋画报》看西方科技在中国的传播 期刊论文 2010, 2010 王斌; 戴吾三; WANG Bin; DAI Wusan 收藏  |  浏览/下载：4/0 High accuracy star image locating and imaging calibration for star sensor technology (EI CONFERENCE) 会议论文 6th International Symposium on Precision Engineering Measurements and Instrumentation, August 8, 2010 - August 11, 2010, Hangzhou, China Zhang S.; Zhang Z.; Sun H.; Wang Y. 收藏  |  浏览/下载：13/0  |  提交时间：2013/03/25 Today aircraft attitude measurement technology plays an important role in an aircraft system because it can provide orientation for aircraft in action. Lately star sensor technology used in aircraft attitude measurement has become more and more popular because of its high accuracy  light weight  without attitude accumulation errors and other advantages. There are three main steps for star sensor to measure aircraft attitude  star image locating  star identification and attitude tracking. The latter two steps are based on the accuracy of star image locating. So it's critical to make efforts to advance the accuracy of star image locating. Some imaging errors  such as spherical aberration or coma aberration  also have negative effect on the accuracy of star image locating  of which the effect is necessarily reduced as well. At the beginning of this article  the structure of star sensor hardware is introduced. Secondly three methods for star image locating are described specifically  which are traditional centroid method  Gauss quadric fitting method and improved Gauss quadric fitting method. Subsequently an imaging calibration method is described for the purpose of reducing the effect of imaging errors. Finally the experiment shows that the accuracy of the star sensor is 2-arc-second. 2010 SPIE.   A design of beam shaping unit for 193nm lithography illumination system using angular spectrum theory (EI CONFERENCE) 会议论文 6th International Symposium on Precision Engineering Measurements and Instrumentation, August 8, 2010 - August 11, 2010, Hangzhou, China Zhao Y.; Gong Y.; Li S.; Zhang W. 收藏  |  浏览/下载：16/0  |  提交时间：2013/03/25 Off-axis illumination (OAI) technology is widely used to enhance resolution for deep ultraviolet lithography. The realizing methods of OAI include geometrical optics method and physical optics method. However  the former has the disadvantage of weak intensity distribution controlling ability  and the latter introduces simulation errors evidently when dealing with near field diffraction propagation. A diffractive optical element (DOE) designing method using plane wave angular spectrum theory is presented in this paper. Several kinds of OAI modes at near field away from DOE can be realized  and simulation errors and the size of illuminator are also reduced. According to studying the relationships of the sampling point distance of DOE  light beam propagation distance  and the structure of the beam shaping unit  a method of determining the designing parameters is discussed. Using this method  several illumination modes are realized  and simulation results show that all diffraction efficiencies reach up to 84%. The method of DOE manufacturing is analyzed at last  and it is proven to be feasible. 2010 SPIE.   普通笔记本电脑的新功能———探测地震 期刊论文 中学生英语(初中版), 2010, 页码: 38-39 作者:  蒋重母[1] 收藏  |  浏览/下载：2/0  |  提交时间：2019/04/30 笔记本电脑  加速计  探索与发现  科克伦  automatically  斯坦福  台式电脑  智利大学  洛杉矶地区  latter