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西南印度洋中脊地质构造对地幔部分熔融的影响:深海橄榄岩尖晶石成分证据

慢速-超慢速扩张西南印度洋中脊普遍发育转换断层,洋脊分段性明显,是研究地质构造与地幔部分熔融关系的理想场所。对西南印度洋中脊(52°20′53°30′E)Gallieni转换断层与Gazelle转换断层之间洋脊段6个站位的深海橄榄岩研究发现:尖晶石Cr#的变化范围为0.194～0.329,对应的地幔部分熔融程度为7.6%～13.0%,反映全球洋中脊系统中低程度的地幔部分熔融,并且离转换断层近的地幔部分熔融程度低于洋脊分段中心,这种差异除了受转换断层的冷却作用影响外,还可能与洋脊分段中心更强的岩浆抽提作用有关。将研究区与全球其他洋脊对比发现,尖晶石Cr#及对应的地幔部分熔融程度随洋脊扩张速率的降低而降低,在探讨地幔部分熔融程度与洋脊扩张速率的相关性时,通过对转换断层效应的校正,能够更准确地反映地幔部分熔融程度随洋脊扩张速率的变化趋势。     

基于改进的两步移动搜寻法的贫困区小学教育资源空间可达性分析——以重庆市黔江区为例

针对贫困区基础教育资源分布中出现的教育资源空间配置不合理等问题,以连片特困区一一武陵山片区的重庆市黔江区为例,以自然村尺度进行测算,重点研究并解决了贫困区教育资源空间布局现状的评估技术,以及两步移动搜寻法在农村贫困山区的关键技术改进和实现,并从供给和需求角度出发评价了教育资源的空间可达性。结果表明两步移动搜寻法适用于评估贫困山区教育资源的空间配置状况和分布情况;研究区教育可达性较高的地区不及需求总数的30％,分布在地形相对平坦,海拔较低的地区,服务范围内的学校多为中心校和实验小学,师资和占地面积优势大,但整体可达性并不理想。为相关部门有效配置教育资源,提出了“跑教”提升师资力量和恢复原有教学点等合理化建议。     

Pareto’s law and sample size: a case study of China’s urban system 1984–2008

While Pareto’s law has been widely supported by empirical evidence in urban studies, past studies have focused on finding best fits for city rank-size distribution. A main concern with Pareto’s law is the truncation of sample selection, for which few studies have examined it directly. This study tests three existing threshold methods (number threshold, size threshold, and urban population percentage threshold) using China’s city system as a case study. In addition, this study proposes a new method based upon the percentage threshold of the total number of cities. A systematic analysis is applied to examine the relationship between Pareto exponent and sample size using different threshold methods. The results show that Pareto exponent is sensitive to sample size and the truncation point. Including only large cities is problematic because a slight change in the truncation point will yield quite different results of Pareto exponent. In addition, the new method, the percentage threshold of the total number of cities method, presents an advantage over previous methods, in that this method yields a consistent set of results over a wide range of thresholds. Finally, when using this new method with China’s city system, the Pareto exponent presents a turning point in 1996, representing China’s transition from a planned economy to a more market oriented economy during that period.     

Distributed Parallel Computing in Stochastic Modeling of Groundwater Systems

Stochastic modeling is a rapidly evolving, popular approach to the study of the uncertainty and heterogeneity of groundwater systems. However, the use of Monte Carlo‐type simulations to solve practical groundwater problems often encounters computational bottlenecks that hinder the acquisition of meaningful results. To improve the computational efficiency, a system that combines stochastic model generation with MODFLOW‐related programs and distributed parallel processing is investigated. The distributed computing framework, called the Java Parallel Processing Framework, is integrated into the system to allow the batch processing of stochastic models in distributed and parallel systems. As an example, the system is applied to the stochastic delineation of well capture zones in the Pinggu Basin in Beijing. Through the use of 50 processing threads on a cluster with 10 multicore nodes, the execution times of 500 realizations are reduced to 3% compared with those of a serial execution. Through this application, the system demonstrates its potential in solving difficult computational problems in practical stochastic modeling.     

A design of three-dimensional spatial data model and its data structure in geological exploration engineering

The key to develop 3-D GISs is the study on 3-D data model and data structure. Some of the data models and data structures have been presented by scholars. Because of the complexity of 3-D spatial phenomenon, there are no perfect data structures that can describe all spatial entities. Every data structure has its own advantages and disadvantages. It is difficult to design a single data structure to meet different needs. The important subject in the 3-D data models is developing a data model that has integrated vector and raster data structures. A special 3-D spatial data model based on distributing features of spatial entities should be designed. We took the geological exploration engineering as the research background and designed an integrated data model whose data structures integrats vector and raster data by adopting object-oriented technique. Research achievements are presented in this paper.     

INTERANNUAL TO INTERDECADAL VARIATIONS OF THE REGIONALIZED SURFACE CLIMATE OF THE UNITED STATES AND RELATIONSHIPS TO GENERALIZED FLOW PARAMETERS

This analysis attempts to discern primary causes of interannual and interdecadal climate variations for precipitation and temperature regions of the conterminous United States. Varimax rotated principal components analysis of annual climate division data is used in the derivation of nine precipitation and five temperature regions. Each region's time series is examined for underlying linear trends, representing long-term climate change, and tests for variance changes, to determine regional climate variability shifts. The first six precipitation components, representing the entire eastern half of the country and the Northwest, displayed significant temporal increases. Of these, four displayed significant increases in interannual variability through time. For temperature, only the Southwestern region showed a significant change (increase) through time. However, significant reductions in temperature variability were confirmed for three regions. To determine the causes of the derived climate shifts, correlation analysis was performed with various atmospheric teleconnection indices. Precipitation trends are most strongly associated with variations in the Southern Oscillation Index (SOI) at the interannual time scale while interdecadal variations are associated more with variations in the Pacific/North American (PNA) teleconnection. Both interannual and interdecadal variations of regional temperature are most strongly related to the PNA, except for the Southwest, which showed a significant correlation to the SOI. This suggests that El Niño/Southern Oscillation (ENSO) events are the source for much of the precipitation change evident in the eastern and Northwestern United States and temperature change in the Southwest. [Key words: climate change, precipitation, temperature, El Niño, Southern Oscillation, United States climate.]     

集体建设用地流转信息发布与电子交易系统设计及应用

在深入研究重庆地票制度基础上,根据传统地票交易管理模式,设计了基于互联网的B/S构架系统,实现了交易信息推送发布、交易管理、态势分析和收益分配溯源等一系列功能,构建了土地流转网上交易平台,并依托课题项目在重庆城乡统筹示范区开展农村土地流转过程数字化监管技术集成及应用示范,替代纯文本、纯人工的工作管理环境,以一体化的数据管理方式为土地流转的管理和相关决策提供信息化手段与支持。