共查询到20条相似文献,搜索用时 46 毫秒
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《世界港口交通地图集》是中国地图出版社首次利用世界地图数据库编制出版的专题图集,该图集打破了传统的制图方式,完全借助于数据库制图的技术手段,开启了利用小比例尺世界基础地理底图数据库制作专题地图的新篇章。从地图选题、结构设计、地图投影、色彩设计、专题符号、读图方法等方面详细论述利用数据库制图技术编制地图的原则、方法和特点。 相似文献
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九寨沟是国家级自然保护区和重点风景名胜区。并载入联合国的《世界自然造产名录》.该沟生态环境十分脆弱,科学研究程度还相当低.两个国家自然科学基金课题对基生态环境进行了综台系统的研究,在此基础上编制而成的专题系列图填补了该区没有一套较完整图件的空白.文章介绍了系列图的编制背景、意义、选题、方法及特点等内容. 相似文献
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福建省生态环境综合系列图编制 总被引:1,自引:0,他引:1
福建省生态环境综合系列图是数字福建应用项目《福建省生态环境动态监测与管理系统》中数据库建设的一个重要基础工作,包括生态环境类型图、生态环境评价图、生态功能区划图以及地势图、地貌图、土壤图、植被图、土地利用图等。编制工作是在参考各种图件和文字等资料基础上,以遥感(LandSatETM)为主要信息源,根据影像特征的差异勾绘生态环境单元并记录各单元一系列相关信息,根据单元图属性派生其它图(地势图除外)。编制过程中着重解决了各专题图的分类系统和编码系统、多源信息复合、遥感综合系列制图与地图演绎法结合应用、3S技术的综合应用、多种制图技术的综合应用等问题。 相似文献
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《广州市政务地图册》的自然基础图组,系统地表现了广州市的地势起伏、地貌类型、土地利用情况、地质构成和矿产资源分布等,本文以此为研究对象,总结介绍了该图组编制的设计与编制方案,从而尽可能地为这类图组的设计与编制提供参考。 相似文献
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《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
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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
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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
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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
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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
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