共查询到20条相似文献,搜索用时 46 毫秒
1.
首先对地球首子午线在不同时期的定义进行了分析和总结,进一步明确了当前对地球首子午线的严格定义,澄清了地球首子午线即过格林尼治天文台的子午线这一模糊认识。同时,结合我国月球探测工程的需要,分析了目前IAU推荐的月球首子午线定义和Bryce Walden等人提出的月球首子午线定义的优缺点。最后,对我国月球探测工程中坐标系的选择提出了建设性的意见。 相似文献
2.
3.
又是一年月圆时,年年望相似的明月如今离人类更近了。随着人类第二次探月高潮拉开序幕,来自地球的测绘科技文明与九天嫦娥共舞。测绘月球,绘制三维月球地图,搭建月球空间信息平台,测绘科学家正在全力谋划,助人类踏上梦想的天阶。2003年3月1日,我国政府正式启动了月球探测计划。我国对月球的探测计划具有非常科学的目标,重点突出,起点很高,需要与月球探测相关的各项科学技术的有力保障。配合我国月球探测计划,有关月球测绘的研究受到我国测绘界的高度重视。国家测绘局密切关注我国科技发展动向,积极配合探月工程,在今年发布的《测绘科技发展”十一五”规划》中明确提出,实施月球测绘技术研究,为月球探测工程提供保障。在我国测绘工作开始不断从陆地向海洋、深空拓展的新形势下,月球测绘不仅对我国探月工程有着极为重要的现实意义,而且将引领测绘工作向更高更新的方向健康发展。[编者按] 相似文献
4.
5.
本文提出了月球摄影测量数据处理系统的设计原则,探讨了月球摄影测量数据处理系统的组成和研究的内容,分析了在月球探测摄影测量数据处理中,首先应该解决的关键技术问题。结论:对月球探测摄影测量数据处理系统的研究,可以保障月球探测卫星工程测绘月球表面三维影像图及地形图任务的完成,同时,也可以为后续的月球探测计划提供摄影测量的基础理论、技术、方法和实践经验。 相似文献
6.
月球的地质特征和矿产资源及我国月球探测的科学目标 总被引:2,自引:0,他引:2
近5 0年来,月球探测在人类宇宙探测历程中占有重要的地位。尽管目前我们对月球的认识还很肤浅,但是可以说,月球是人类探测与研究程度最高的地外天体。进入2 1世纪,人类对月球探测的热情有增无减,探测的规模更大,参与的国家更多,重返月球、建立月球基地的目标更为明确,月球资源的开发利用已经提上了议事日程。我国的月球探测工程已经排出了时间表:2 0 0 7年完成绕月工程,2 0 1 0年完成落月工程,2 0 2 0年完成返回。我们凭借自己的国力和拥有的科学技术能力,将为月球探测做出应有的贡献。一、月球的物质成分过去一直把月球地质单元划分为月海… 相似文献
7.
8.
9.
10.
由于地球是弹滞体,根据牛顿理论,由于地球的自转作用,地球应该呈扁椭球状。18世纪,法国科学院派遣了两支测量队分赴拉普兰和秘鲁对地球的子午线弧长进行了实测,最终证实了地球是扁椭球。本文分别讨论了子午弧长随地心、大地、归化纬度的变化规律,数值计算结果表明:以大地纬度和归化纬度而论.1°子午线弧长随着纬度的增大而逐渐变长;但以地心纬度而论,1°子午线弧长随着纬度的增大而逐渐变短。 相似文献
11.
《International Journal of Digital Earth》2013,6(1):80-87
Abstract Cultures throughout the world are associating with the rivers. People depend upon the rivers and their tributaries for food, water, transport, and many other aspects of their daily lives. Unfortunately, human beings have not calculated the accurate lengths for the great rivers even today. The lengths of the rivers are very different in popular textbooks, magazines, atlases and encyclopedias, etc. To accurately determine the lengths of the principal rivers of the world, the combination of satellite image analysis and field investigations to the source regions is proposed in this paper. The lengths of the Nile, Amazon, Yangtze, Mississippi, Yellow, Ob, Yenisey, Amur, Congo and Mekong, with lengths over or close to 5000 km, were calculated using the proposed method. The results may represent the most reliable and accurate lengths of the principal rivers of the world that are currently achievable. 相似文献
12.
13.
软科学这一术语是70年代在国外提出的.然而30多年以来,它在国外不仅未得到普遍的承认,而且对软科学的定义也还未能达成大体上一致的共识.而在改革开放后的中国,出于决策科学化和民主化的需要,经过一些领导人的提倡和支持,特别是通过1986年召开的软科学座谈会及1994年召开的全国软科学工作会议,软科学事业得到了蓬勃的发展.据初步统计,截止1998年底全国共有软科学研究机构1224个,研究人员32655人,初步形成了一支较为强大的研究队伍,并取得了数百项覆盖多个领域的研究成果,为支持各级各类的决策发挥了一定的作用. 相似文献
14.
Tobias Nilsson Benedikt Soja Kyriakos Balidakis Maria Karbon Robert Heinkelmann Zhiguo Deng Harald Schuh 《Journal of Geodesy》2017,91(7):857-866
The very long baseline interferometry (VLBI) Intensive sessions are typically 1-h and single-baseline VLBI sessions, specifically designed to yield low-latency estimates of UT1-UTC. In this work, we investigate what accuracy is obtained from these sessions and how it can be improved. In particular, we study the modeling of the troposphere in the data analysis. The impact of including external information on the zenith wet delays (ZWD) and tropospheric gradients from GPS or numerical weather prediction models is studied. Additionally, we test estimating tropospheric gradients in the data analysis, which is normally not done. To evaluate the results, we compared the UT1-UTC values from the Intensives to those from simultaneous 24-h VLBI session. Furthermore, we calculated length of day (LOD) estimates using the UT1-UTC values from consecutive Intensives and compared these to the LOD estimated by GPS. We find that there is not much benefit in using external ZWD; however, including external information on the gradients improves the agreement with the reference data. If gradients are estimated in the data analysis, and appropriate constraints are applied, the WRMS difference w.r.t. UT1-UTC from 24-h sessions is reduced by 5% and the WRMS difference w.r.t. the LOD from GPS by up to 12%. The best agreement between Intensives and the reference time series is obtained when using both external gradients from GPS and additionally estimating gradients in the data analysis. 相似文献
15.
16.
17.
In this letter, we are trying to resolve the electromagnetic problem for the movements of the superconducting particles of the protoplanetary cloud in the magnetic field of Saturn. The force of levitation (Meissner-Ochsenfeld phenomenon) is introduced to the field of planetary science for the first time. It is shown from our theoretical analysis that rings of Saturn might have a superconducting origin, and rings might levitate within magnetic equator plane of the planet. 相似文献
18.
19.
根据残差二次型次小与最小之差进行整周模糊度确认的关键是差值的分布,只有得到了合理的差值分布才可确定合理的界值.文中基于原有的两种方法及这两种方法的不足,从理论上导出了满足条件的差值分布,并作了一定的说明. 相似文献
20.