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2013年,全球矿业经济继续下行,但全球矿业政策和管理的改革仍按既定方向和节奏进行.近30个国家计划通过、正在通过或已经通过修改矿法,对本国的矿业投资环境进行调整.非传统矿业国也借助矿产资源的新发现,完善矿产资源管理制度,希望推动经济新的发展.许多国家为增加本国的矿产资源收益,纷纷提高资源税费.在放宽外资投资矿业的准入条件的同时,对矿产开采可能造成的环境影响也更加重视. 相似文献
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《The Cartographic journal》2013,50(4):315-322
Abstracttitle/>In the area of volunteered geographical information (VGI), the issue of spatial data quality is a clear challenge. The data that are contributed to VGI projects do not comply with standard spatial data quality assurance procedures, and the contributors operate without central coordination and strict data collection frameworks. However, similar to the area of open source software development, it is suggested that the data hold an intrinsic quality assurance measure through the analysis of the number of contributors who have worked on a given spatial unit. The assumption that as the number of contributors increases so does the quality is known as ‘Linus’ Law’ within the open source community. This paper describes three studies that were carried out to evaluate this hypothesis for VGI using the OpenStreetMap dataset, showing that this rule indeed applies in the case of positional accuracy. 相似文献
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Robert Hage 《Marine Policy》1984,8(1):2-15
This is a historical review of Canadian policy at the Third UN Conference on the Law of the Sea. Canadian objectives with regard to the territorial sea, fisheries, pollution prevention and the continental shelf are outlined and the role played by the Canadian delegation at UNCLOS is described. The article then examines the impact of the Convention on Canada, particular attention being paid to the Canadian Exclusive Economic Zone and the Canadian role in the controversy over seabed mining. The author concludes by arguing that Canada was a major beneficiary of the Convention, but that US opposition has placed the future of the Convention in jeopardy. 相似文献
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Daniel?F.?MerriamEmail author Lawrence?J.?Drew John?H.?Schuenemeyer 《Natural Resources Research》2004,13(4):265-271
Zipfs Law originally was proposed as a guide to a statistical distribution in social studies. The law describes a relationship between size and rank of discrete phenomena. It is a variant of Paretos 1927 Law known as the 80/20 rule and is similar to Bodes Law in concept. The relationship described by Zipfs Law is a succession of order data with the largest followed by half the size for the next largest, which in turn, the next is half that size, and so on. In geology, it has been used with moderate success in resource assessment of mining and petroleum. In essence, it predicts how many entities of a certain size may be left in a sequence of decreasing size assuming the largest has been ascertained. Examples of applications would be plotting the rank and size of ore deposits or oil fields to determine how many deposits remained undiscovered and their size. After a flurry of papers in the 1970s and 1980s, application of the law apparently either was successful and thus not reported in way the literature or was determined to be ineffectual and its use discontinued, but either way the law lapsed into obscurity. Examples of oil- and gas-field size in Kansas, the occurrence of historic earthquakes that affected the state, and size of anticlines (plains-type folds) are presented to illustrate application and limits of Zipfs Law. 相似文献
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本文就各级测绘行政管理部门,如何充分发挥政府行政管理作用,履行依法行政职能,保障和促进测绘事业的健康持续发展等重要问题。分析了现代测绘管理基本特点,论述了测绘管理部门依法行政和依法管理的基本思路和工作要求。 相似文献
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根据氡的迁移机制(如扩散、对流、大气抽吸等),采用理论计算的方法,得出埋入地下的探杯中的氡浓度与杯口邻近土壤空气中的氡浓度达到自然状态平衡约需0.7—10小时,而杯中氡浓度与其短寿衰变子体达到放射性平衡需4小时。因此,一般认为两者共需4.5—12小时左右。钍射气与其短寿命子体达到放射性平衡的时间需3—4天。当钍含量高出背景值时,探杯的照射时间则需3—4天。用ZnS探杯埋入地下做了野外试验,与上述理论计算结果基本相符。对这种平衡过程的了解,不仅为选取最佳的埋杯时间提供了理论依据,而且也有助于各种测氡方法的异常解释。 相似文献
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针对由Gardner-Russo函数描述的特征土壤,在双饱和度坐标系中,探讨了常规节点间导水率估计与量纲一水平达西平均(k*H)和量纲一垂直达西平均(k*V)的差异.k*H是相邻两节点饱和度的函数,而k*V也是空间步长(Δx)和特征参数(α)的函数.对水平非饱和流,算术平均高估导水率,而几何与调和平均低估导水率;从相对误差空间分布看,几何平均优于算术和调和平均.对垂直非饱和流,随Δx(或α)的增大,常规估计的相对误差空间顺(或逆)时针旋转并缩小,从而降低模型准确性.k*H等值线具有对称性,而k*V不具对称性;仅当Δx或α足够小时,k*H才趋近于k*V.因此,为提高非饱和流数值模拟的准确性,必须采用精确的达西平均来计算节点间导水率. 相似文献