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排序方式: 共有1806条查询结果,搜索用时 912 毫秒
81.
GIS可视化技术与PDM的集成研究 总被引:1,自引:0,他引:1
传统的产品数据管理PDM(Product Data Management.PDM)系统无法直观地描述产品的空间分布,难以进行基于产品空间信息的统计分析,可视化效果较差.从GIS和PDM各自的功能特点出发,讨论GIS可视化技术与PDM集成的可行性及特点;分析GIS-PDM集成系统(图文信息管理子系统和客户关系管理子系统)的基础框架及 相似文献
82.
传统的GIS开发方式多采用结构化的设计思想,对于不同GIS信息系统的建设.需要重复去设计、开发相关模块,开发效率较低.文中将组件重用思想应用到GIS开发实践中,总结基于组件的软件重用技术,探讨GIS开发中常见可重用组件接口的设计思路,包括:主界面接口设计、空间数据库互操作接口设计和查询接口设计.通过开发实践证明,基于组件重用思想的GIS开发具有良好的开放性,可以高效、快速地开发出更稳定的应用系统,显著降低开发成本. 相似文献
83.
SAR图像可以看作是真实反映地物后向散射特性的无噪图像与相干斑噪声的乘积,通过贝叶斯估计从图像观测值估计出图像真值即可去除相干斑.而贝叶斯去斑的关键在于建立能与SAR图像特性相匹配的先验信息模型.用MembraneMRF模型对先验信息建模,克服了以往所用GMRF模型对参数估计十分敏感的问题,并通过对该模型邻域结构的自适应调整来分类处理处于匀质区域和含结构特征区域的像元,在有效抑制相干斑的同时较好地保持图像的结构特征.仿真和实际SAR图像数据的实验结果,验证了所提方法的有效性. 相似文献
84.
85.
赵恒轩 《成都信息工程学院学报》1999,(3)
介绍美国、欧洲、中国90年代高级天气雷达监测网建设与发展概况和瑞士的Met-Net高级气象雷达数据网系统的主要技术特色 相似文献
86.
Kyoung-nam Jo Kyung Sik Woo Hyoun Soo Lim Hai Cheng R. Lawrence Edwards Yongjin Wang Xiuyang Jiang Ryeon Kim Jae Il Lee Ho Il Yoon Kyu-Cheul Yoo 《Quaternary Science Reviews》2011,30(9-10):1218-1231
Textural and stable isotopic records from the absolute-dated stalagmite of the Daeya Cave (DY-1) provide new insights into the climatic evolution of the Korean Peninsula during the Holocene and Eemian climatic optima. The stalagmite yielded ages of 8572 ± 227 to 5907 ± 158 and 1,23,456 ± 535 to 1,19,837 ± 1089 years, which coincide with the Holocene and Eemian climatic optima, respectively. The stalagmite’s δ13C record closely resembles previously reported Chinese speleothem δ18O data. Thus it can be suggested that textural and geochemical results of the DY-1 reflect East Asian monsoon intensity, which is forced by summer insolation patterns in the northern hemisphere. Lighter carbon isotopic compositions, well-developed fibrous calcite crystals, and their relatively faster growth rate in the stalagmite sample are interpreted to reflect the warmest and wettest climate conditions of the Holocene and Eemian interglacials. Both climatic optima took place when insolation was decreasing from its maximum level, temperature in Greenland was highest, and sea level approached its maximum level. These climatic optima also coincide with decreasing Antarctic temperatures. Compared the DY-1 data to other proxies, it is suggested that the Holocene and Eemian climatic optima developed through a balance among boreal insolation, monsoon intensity, and sea level (also continental ice volume), which are the main climatic forcing factors in the northern hemisphere. These trends also follow the bi-polar seesaw mechanism as previously described. 相似文献
87.
88.
The geochemical behaviours of 26 elements in deep-sea drill core sediments from the Indian Ocean have been investigated with
INAA, including Na, K, Ca, Sc, Cr, Fe, Co, Rb, Sr, Zr, Sb, Cs, Ba, La, Ce, Nd, Sm, Eu, Tb, Yb, Lu, Hf, Ta, Au, Th and U. Their
distribution patterns with depth are also discussed. In terms of the enrichment factors of the respective elements, their
residence times in the sea have been calculated by the least squares fitting and are compared with the previous results. 相似文献
89.
Chai Sheli 《吉林大学学报(地球科学版)》1989,(3)
本文从地质地球化学角度对峪耳崖金矿床进行了详细研究,认为该金矿是典型的岩浆热浪型脉状金矿床,金矿与峪耳崖花岗岩(即矿床的主要围岩)为同源岩浆作用的产物,而其源岩物质可能来自深部地壳。黄铁矿中Co/Ni比为1.58,石英中La/Yb比为2.95,δ~(34)S_∑为+2.6‰,δ~(13)O水为+7.03‰,δD为-88.4‰,δ~(13)C为-4.18‰,成矿温度为305~343℃,pH为6.2~6.8,石英包裹体成分中Cl~->F~-、Na~+>K~+,金可能是以Na[AuCl_2],Na[Aucl_4]或Na[AuS]等络合物形式迁移。 相似文献
90.
The unique and remarkable post-independence demographic transition of Singapore, from high to low growth, has been accompanied by an equally spectacular social transformation. Both population control and social change have a positive impact on the fertility trend. Singapore's population policy has been dictated much by the crisis consciousness of the leadership which has been able to create a high degree of awareness among its population with regard to fertility.Ironically, public response to the government's population control has been too successful, particularly so among the upper-income groups. This has recently prompted the government to examine the sustained low fertility rate which, if unchecked, will bear serious social, economic, political and defence consequences in 20 to 30 years time. The aim of the current fertility campaign is to reachieve the replacement level, first reached in 1975, through the correction of the lopsided procreation pattern. As such, some disincentives have remained or been removed, while several new incentives and measures have been introduced. Observations are made with regard to the future fertility trends. 相似文献