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Geographic information has become central for data scientists of many disciplines to put their analyzes into a spatio-temporal perspective. However, just as the volume and variety of data sources on the Web grow, it becomes increasingly harder for analysts to be familiar with all the available geospatial tools, including toolboxes in Geographic Information Systems (GIS), R packages, and Python modules. Even though the semantics of the questions answered by these tools can be broadly shared, tools and data sources are still divided by syntax and platform-specific technicalities. It would, therefore, be hugely beneficial for information science if analysts could simply ask questions in generic and familiar terms to obtain the tools and data necessary to answer them. In this article, we systematically investigate the analytic questions that lie behind a range of common GIS tools, and we propose a semantic framework to match analytic questions and tools that are capable of answering them. To support the matching process, we define a tractable subset of SPARQL, the query language of the Semantic Web, and we propose and test an algorithm for computing query containment. We illustrate the identification of tools to answer user questions on a set of common user requests. 相似文献
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Analytical solutions for advective–dispersive solute transport in double‐layered finite porous media
Peter John Cleall 《国际地质力学数值与分析法杂志》2011,35(4):438-460
Analytical solutions for advection and dispersion of a conservative solute in a one‐dimensional double‐layered finite porous media are presented. The solutions are applicable to five scenarios that have various combinations of fixed concentration, fixed flux and zero concentration gradient conditions at the inlet and outlet boundaries that provide a wide number of options. Arbitrary initial solute concentration distributions throughout the media can be considered via explicit formulations or numerical integration. The analytical solutions presented have been verified against numerical solutions from a finite‐element‐based approach and an existing closed‐form solution for double‐layered media with an excellent correlation being found in both cases. A practical application pertaining to advective transport induced by consolidation of underlying sediment layers on contaminant movement within a capped contaminated sediment system is presented. Comparison of the calculated concentrations and fluxes with alternative approaches clearly illustrates the need to consider advection processes. Consideration of the different features of contaminant transport due to varying pore‐water velocity fields in primary consolidation and secondary consolidation stages is achieved via the use of non‐uniform initial concentration distributions within the proposed analytical solutions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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中国崛起的国际地缘战略研究 总被引：5，自引：2，他引：3
围堵与反围堵是世界历史上大国崛起的常态。本文立足于结构现实主义的国际关系原理,运用地理学的空间相互作用和区位选择等理论,探讨中国在和平崛起过程中权力一利益半径外延的必然性、与本文为竞争利益空间而发生的全球性战略互动,以及由此诱发的周边地缘风险。作者指出,由于区域的非均质性,中国向外实现战略突破时只能依循非均衡路径,即集中优势资源在空间阻滞效应较弱、"投资"回报较高的局部地区率先实现突破,并以此为"极轴"向其他地区辐射战略影响。在全球层面上,由于综合国力的结构性缺陷,目前中国宜把战略资源优先投放到"低政治"领域,运用渗透性较强的经济手段,争取尽快在非洲、拉美与西欧等地获取必要的战略立足点;而在区域层面上,中国应追求在"高政治"领域有所建树,选择与中国在地理上接近、文化亲缘性较强、战略互信度较高的国家进行对外拓展,如:巴基斯坦、缅甸、蒙古、塔吉克斯坦和哈萨克斯坦等地。两者相辅相成,共同组成了21世纪中国和平崛起的国际地缘战略。 相似文献
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地震危险性与核电厂密闭可靠性的评价方法 总被引：1，自引：0，他引：1
本文就考虑地震危险性时，核电厂安全壳的防泄露可靠性的评价方法进行了理论研究，探讨了地震模型问题中的参数确定的一些方面，给出了可靠性评价的总体思路、分析方法及具体步骤，确定了要考虑的不定参数及其描述，并进而利用概率断裂力学推导出可靠性计算的一般公式。 相似文献
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Roger Few 《The Geographical journal》2000,167(2):111-124
Critical analyses of public involvement in conservation projects in developing countries commonly point toward imbalances of power between project agencies and communities and the persistence of top-down patterns of decision-making. Taking an actor-oriented research approach, this paper probes beneath the surface patterns to analyse the complex socio-political mechanisms at work in the negotiating arena represented by public participation in project planning. The discussion is based on a case study of community involvement in the planning of protected areas in Belize. Detailed analysis of the power relations and tactical interactions between different actors in the negotiating arenas revealed that planner/community relations in the case study were dominated by a process identified as 'containment'. Containment refers to a strategic management of public involvement by the planning agencies, and it hinged on three fundamental social actions: avoidance of conflict; exclusion of dissent; and control over knowledge and procedure. Actions by local stakeholders that served to undermine containment constitute 'counter-containment'. The paper discusses these mechanisms in depth, before developing a comparative analytical framework of containment and counter-containment to help explain disparities in planning progress between different sites. 相似文献
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《Climate Policy》2013,13(2):232-238
US policy makers are currently evaluating options to reduce domestic carbon dioxide emissions, and several economy-wide cap-and-trade proposals have been put forward in the 111th Congress. Despite mounting enthusiasm for cap-and-trade, advocates of this approach have had to defend such proposals against the criticisms that prices in the resulting carbon market will be unstable and that the implied costs of policy might exceed society's willingness to pay for the expected environmental benefits. Allowance borrowing has been proposed as one solution to both of these concerns, with firm-level borrowing intended to mitigate the impacts of transient cost shocks, and system-level borrowing intended to hedge against the risk of early technology bottlenecks. Each of these mechanisms, as proposed, relies upon prescribed constraints, such as interest payments or quantity limits, to protect against overuse. This article introduces a novel mechanism that offers qualitatively similar protection—a firm-level deposit on borrowed allowances that is refundable upon repayment of the emissions debt. However, the deposit mechanism is shown to be both more economically efficient and more effective in mitigating performance risk, when compared to the existing alternatives. 相似文献
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Soil cover is a widely-used but relatively new method for solid waste containment. Standard while site-specific procedures
for cover design, monitoring, and evaluation are needed to insure reliable cover performance. This paper presents a review
of soil cover types, design principles and procedures, cover monitoring, and long-term performance modeling. Cover types and
cover design are introduced with the general concepts and discussed on their specific applicabilities in different circumstances.
Detailed discussion is given on unsaturated flow system properties and their field measurements, including methods, apparatuses/equipments
and their advantages and disadvantages. Several unsaturated flow simulators are discussed and compared with regards to their
simulation capacities for critical parameters closely related to soil cover performance such as runoff, infiltration and evaporation.
Finally, research subjects are suggested for future work for better soil cover monitoring and modeling. 相似文献
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根据黏弹性人工边界的基本原理,结合有限元分析软件ABAQUS和MATLAB辅助程序,在地基有限区域上添加黏弹性人工边界并实现极限安全地震动的输入。基于ABAQUS软件平台,对CPR1000安全壳构建了土-结构相互作用体系的数值模拟模型,分析其在极限地震动下的动力响应,并将计算结果与考虑刚性基础的安全壳结构响应数据进行对比。结果表明:核电站CPR1000安全壳结构在极限安全地震动下仍能保持良好的密闭性。考虑土-结构相互作用后分析所得安全壳结构受到的应力、加速度峰值和相对位移均有所增大,使用刚性地基模型要偏于危险。 相似文献