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根据水下河床水深点测量采样的既有规则格网法又有三角形法二者优点的四边形法绘制河床等深线图,该法数据结构简单,编程方便,速度快。文 图表对水下对河床水深点的数据数据结构,四边形的构万能主等深线的追踪作了详细的讨论。 相似文献
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ABSTRACT The foundation of modern Digital Earth frameworks is the Discrete Global Grid System (DGGS). To standardize the DGGS model, the Open Geospatial Consortium (OGC) recently created the DGGS Abstract Specification, which also aims to increase usability and interoperability between DGGSs. To support these demands and aid future research, open implementations are necessary. However, several OGC conformant DGGSs are not available for researchers to use. This has motivated us to develop an open-source web service that allows users to create quadrilateral grids based on the rHEALPix DGGS. In this paper, we describe the implementation of the web service, including issues and limitations, and demonstrate how discrete global grids and regional grids can be created. Lastly, we present examples that show how vector data sets can be modeled and integrated at different levels of resolution – a key benefit of the DGGS model. 相似文献
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Pierre Kamgang Gilles Chazot Emmanuel Njonfang Flix Tchoua 《Comptes Rendus Geoscience》2008,340(12):850-857
Mafic rocks from the Bamenda volcanic province along the Cameroon Volcanic Line have been dated from 17 to 0 Ma. Associated with some trachytes and rhyolites, this volcanism covers a period of more than 25 Ma. The studied rocks are basalts to mugearites. Most of them have been contaminated by continental crust during their transit to the surface. The oldest rocks are the most contaminated. One group of samples shows high Eu, Sr and Ba contents. This characteristic is not due to crustal contamination process, but has a mantle source origin. We argue that these characteristics have been acquired by mixing of melts formed by partial melting of mantle pyroxenites with melts formed in mantle peridotites. Such pyroxenites have been observed as mantle xenoliths in the Adamaoua province, and their chemical and isotopic compositions are consistent with such a model. 相似文献
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Jean-Pierre Gauthier Emmanuel Fritsch Bertha Aguilar-Reyes Alain Barreau Bernard Lasnier 《Comptes Rendus Geoscience》2004,336(3):187-196
A Mexican opal from the state of Jalisco has a bidisperse, perfectly ordered structure with framboid silica lepispheres of two different diameters. Its structure has been determined by the observation of a vicinal section, close to a dense plane. Fresh breaks along a vicinal plane emphasized regular steps, which were studied by means of SEM. We have been able to propose unit cell models, theoretical positions of the two sets of spheres, and probable space group, P63/mmc. This structure arranges similarly to that of a diatomic compound having an AB2 stoichiometry and corresponds to a cubic (MgCu2-type) or hexagonal (MgZn2-type) Laves phase. This last variety seems to be the most probable structure. To cite this article: J.-P. Gauthier et al., C. R. Geoscience 336 (2004). 相似文献
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二维潮流数学模型的四边形等参单元法 总被引:4,自引:0,他引:4
本文在有限差分和有限元法的基础上,采用四边形等参单元,对在河海域进行了潮流数学模型计算,计算表明:该方法既能较好地拟合边界,又可减少网格划分等前期工作,所得结果与实测资料基本一致。 相似文献
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