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61.
地理信息标准化是很漫长的道路,在实践中常常由于规范性的缺乏而带来很多问题.本文试从提高数据字典的通用性、灵活性和可维护性角度出发,提出了通用基础地理信息数据字典系统的概念,并从规范数据生产过程的角度出发,产生了建立一套全新独立的、由向导生成的数据字典建库方案流程的思路.最后根据以上思路研制开发了空间数据库辅助设计系统. 相似文献
62.
建筑物沉降监测数据分析与处理是一项较复杂的系统工程,本文从自动化处理观点出发,介绍了设计沉降监测专家分析系统的咨询新理念和主体思想,探讨了开发选用的数学模型与开发过程,以期为相关变形监测与分析提供帮助和启示. 相似文献
63.
均匀设计与灰色理论在边坡稳定性分析中的应用 总被引:1,自引:1,他引:0
采用均匀设计安排试验,运用灰色理论中的灰色关联分析考察边坡稳定性影响因素的主次.结果表明,边坡稳定性影响因素的敏感性由大到小依次为:粘聚力、内摩擦角、重度、预应力、锚索间排距、锚索长度、锚固段长度、锚固角.可见,岩体的抗剪强度指标是影响边坡稳定性的最重要参数,其次是岩体的容重,而预应力锚索的设计参数对边坡的稳定性也有一定影响.这一分析结果为边坡开挖设计和加固方案的优化提供了重要依据. 相似文献
64.
阐述了GIS系统的设计原则,建设方案,揭示了GIS系统功能模块的效能,利用Map控件建立信息管理系统,最后探讨了GIS系统在应用领域的发展前景。 相似文献
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本分析了杠杆点的几何含义和统计特征,从杠杆点的保差性,矩阵的摄动和参数估值可靠性的观点出发讨论了杠杆点的不利和有利的两个方面,提出了一个全面的设计空间抗差方案。 相似文献
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This study provides a detailed magnetostratigraphy of sediments composing the Cold Creek cataclysmic flood bar in the Pasco Basin, Washington. Our interpretation suggests onset of Missoula floods or similar events prior to 1.1 myr, later than previously suggested by Bjornstad et al. [Bjornstad, B.N., Fecht, K.R., Pluhar, C.J., 2001. Long history of pre-Wisconsin, Ice Age cataclysmic floods: evidence from southeastern Washington State. Journal of Geology 109 (6), 695-713]. Nonetheless these data suggest that Channeled Scabland features formed over a much longer timespan than commonly cited, that continental ice sheets of the early Pleistocene reached as far south as those of the late Pleistocene, and that similar physiography existed in eastern Washington and perhaps Montana to both generate and route Missoula-flood-like events. This study adds paleomagnetic polarity results from 213 new samples of silts and sands derived from nine new drill cores penetrating the Cold Creek cataclysmic flood bar to our previous database of 53 samples from four boreholes, resulting in a much more robust and detailed magnetostratigraphy. Rock magnetic studies on these sediments show pure magnetite to be the predominant remanence-carrying magnetic mineral, ruling out widespread remagnetization by secondary mineralization. The magnetostratigraphy at eastern Cold Creek bar is characterized by a normal polarity interval bracketed by reversed polarities. Equating the normal zone with the Jaramillo subchron (0.99-1.07 myr) affords the simplest correlation to the magnetic polarity timescale. Western Cold Creek bar was likely deposited during the Brunhes chron (0-0.78 myr) since it exhibits mainly normal polarities with only two thin reversed-polarity horizons that we interpret as magnetic excursions during the Brunhes. 相似文献
70.
Yunchao HAO Zhigang GUO Dejiang FAN 《中国地球化学学报》2006,25(B08):13-13
In the East China Sea (ECS), there are some mud areas, including the south coastal mud area, the north coastal mud area, and the mud area to the southwest of Cheju Island. X-ray fluorescence (XRF) techniques and Thermal Ionization Mass Spectrometry (TIMS) were used to study the high-resolution sedimentary record of Pb concentrations and Pb stable isotopic compositions in the past one hundred and fifty years in the coastal mud of the ECS. Pb concentrations of a ^210Pb dating S5 core in the study area have increased rapidly since 1980, and reached the maximal value with 65.08 μg/g in 2000, corresponding to the fast economic development of China since the implementation of the "Reform and Open Policy" in 1978; ^206Pb/^207Pb ratios generally had stabilized at 1.195 from 1860 to 1966, and decreased gradually from 1966 to 2000, indicating that the anthropogenic source Pb contribution to the ECS has increased gradually since 1966, especially since 1980. Pb concentrations decreased distinctly from 2000 to 2003 and ^206Pb/^207Pb ratios increased from 2001 to 2003, corresponding closely to the ban of lead gasoline from 2000 in China. From 1950 to 2003, there occurred four distinct decrease events of ^206Pb/^207Pb, possibly responding to the Changjiang River (Yangtze River) catastrophic floods in 1998, 1991, 1981 and 1954; from 1860 to 1966, there were two decrease periods of ^206Pb/^207Pb, which may respond to the catastrophic floods of Changjiang River in 1931 and 1935, and 1870. As a result of the erosion and drowning by the catastrophic floods, the anthropogenic lead accumulated in soil and water environments over a long period of time was brought into the Changjiang River, then part of them was finally transported into the ECS, which leads to changes in Pb stable isotopic composition. 相似文献