基于Arc/Info的地貌晕渲法的技术和实践

根据地貌晕渲基本理论和技术,利用Arc/Info制作了彩色晕渲图,并探讨了不同参数下的晕渲效果,最后还尝试了将晕渲图加载到表面视图,以从不同的角度来观察地貌形态。     

Efficient joint-probability methods for hurricane surge frequency analysis

The Joint-Probability Method (JPM) was adopted by federal agencies for critical post-Katrina determinations of hurricane surge frequencies. In standard JPM implementations, it is necessary to consider a very large number of combinations of storm parameters, and each such combination (or synthetic storm) requires the simulation of wind, waves, and surge. The tools used to model the wave and surge phenomena have improved greatly in recent years, but this improvement and the use of very large high-resolution grids have made the computations both time-consuming and expensive. In order to ease the computational burden, two independent approaches have been developed to reduce the number of storm surge simulations that are required. Both of these so-called JPM-OS (JPM-Optimal Sampling) methods seek to accurately cover the entire storm parameter space through optimum selection of a small number of parameter values so as to minimize the number of required storm simulations. Tests done for the Mississippi coast showed that the accuracy of the two methods is comparable to that of a full JPM analysis, with a reduction of an order of magnitude or more in the computational effort.     

中国古今地图时空融合与运营平台建设

古旧地图作为重要的历史地理信息来源,需求日益扩大。本文针对国内缺乏系统全面的古旧地图展示平台的情况,在配准4000幅中国古旧地图的基础上,使用地理信息系统、数据库、SOA、Web Service、ArcGIS API for JavaScript等技术,建设中国古今地图时空融合与运营平台,通过古今地图的套叠对比,在PC端和移动端直观展现地理和人文环境变迁。平台提供对古旧地图影像数据的快速查询检索、展示、输入输出、管理等功能,可为城市规划建设、历史地理研究提供支持。     

导航电子地图质量检测样本库建设方法探讨

为提高导航电子地图质量检测的科学性和检测效率,节约工作成本,国家测绘产品质量检验测试中心于2014年起逐年建设覆盖全国的导航电子地图质量检测样本库。本文详细阐述了导航电子地图质量检测样本库的特点、数据采集技术流程与建库方法,在试点样区内的导航电子地图质量检测中得到了有效应用。     

基于GIS的呼和浩特市近百年街道时空演变及其特征分析

以历史文化名城——呼和浩特市城区为研究区,以GIS为技术平台,运用现代地图、古地图、遥感影像数据以及史料和现代文献,制作了6个典型时期历史街道GIS数据,定量与定性相结合分析了研究区近百余年的街道时空演变过程及其特征。结果显示：研究区近百年的街道时空演变具有“摊饼式”空间扩展特征、先集聚后分散的空间演变特征;解放初期至改革开放时期的街道演变具有向内填充式发展与向北缓慢扩展相结合演变的特点,而快速城市化时期研究区新增街道以原归化、绥远城为中心向四周延伸,呈现出向外扩展的空间演变特征;百余年后的今天,原归化城内的街巷基本消失,而绥远城内的街道基本上保持了清代的棋盘式格局;人口增加、城市规划与建设、集聚与分散以及地质地貌条件等是研究区街道时空演变的主要驱动因素。     

利用高分辨率地球影像研究全球洋壳活断层分布

利用谷歌三维地图勾绘出全球海底现今主要断层构造带的分布图,为观察海洋地壳运动与演化过程提供新的方法和视角,对海底活断层的分布和演化机理、海底扩张、地幔对流等方面的深入研究和探索具有重要意义。     

A detailed measurement of the halo in the coma cluster of galaxies,and its magnetic field

Abstract

A new series of detailed observations of the Coma cluster of galaxies has been undertaken with the aim of better specifying the intergalactic gas component through high dynamic range, combined-telescope observations of the radio emission from the cluster which detect both the cluster-scale and galaxy-scale emission.

By combining these multi-frequency radio maps with a Faraday rotation probe experiment using cluster and background sources, and the published X-ray data, we have been able to estimate the intracluster magnetic field strength independently of the usual assumptions of equipartition. The result is approximately 2 microgauss.

We compare the X-ray and radio distributions in detail, and describe how our combined results suggest that acceleration of the relativistic electrons occurs in situ, and we suggest that the conditions in the cluster provide good physical arguments to support this.     

Correlations among large igneous provinces related to the West Gondwana breakup: A geochemical database reappraisal of Early Cretaceous plumbing systems

The opening and spreading of the Atlantic Ocean between Africa and South America evolved during the Early Cretaceous and were preceded by dramatic tholeiitic (mafic) magmatism and minor silicic and alkaline volcanism. These features are presently recognized from the equatorial regions of Brazil and Africa to the Falklands and South Africa. In southeastern South America, continental flood basalts and related plumbing systems constitute the Paraná Magmatic Province (PMP), whose African counterpart is the Etendeka Magmatic Province (EMP). In northeastern Brazil, dike swarms and sill complexes compose the Equatorial Atlantic Magmatic Province (EQUAMP). As a common feature, these provinces are chemically represented by two prevalent magma types: (1) tholeiitic basalts and basaltic andesites with low Ti (TiO₂ < ～2 wt.%), also including transitional Ti tholeiites with TiO₂ ～ 2.7–1.7 wt.%, and low incompatible element contents. This type is predominantly found in the southern PMP and EMP, with minor occurrences in the EQUAMP. (2) Tholeiitic basalts and basaltic andesites with high Ti (TiO₂ > ～2 wt.%) and incompatible element contents. High Ti tholeiites are relevant in the northern PMP and EMP, and dominant in EQUAMP. Evolved rocks (SiO₂ = 57–65 wt.%) interpreted as byproducts of assimilation and/or fractional crystallization (AFC) processes from high Ti tholeiitic magmas, are scarce (but present) in all three provinces. An accurate analysis of multivariable databases collected from the literature for dikes and sills, including major and trace element and radiogenic isotope data, reveals close similarities in their geochemical signatures. In a paleogeographic reconstruction of West Gondwana, the intrusive remnants of the PMP, EMP and EQUAMP are spread over an area of nearly 10 × 10⁶ km², forming perhaps the most extensive set of plumbing systems on Earth, with a relatively consistent chronology based on a vast collection of K–Ar and ⁴⁰Ar/³⁹Ar data available in the literature. This work provides the first comprehensive data comparison to support the existence of what may have been a single intercontinental-scale magmatic province of West Gondwana.     

基于GPU的全球地形数据加速绘制技术研究

在对基于GPU大规模地形数据快速绘制方法的研究基础上,针对GPU的批量绘制的特点,提出了改进的几何体实例化方法,把它用在全球格网的快速绘制上。把地形数据通过重新编码存储在高度图中,再结合Shader Model 3.0引入的顶点纹理拾取技术,在GPU中进行解码,得到原始的DEM数据,避免了在CPU上执行顶点缓存的更新。实验证明该算法充分利用了新一代GPU的特性,降低了CPU的负担,能达到实时绘制的要求。     

实景地图的空间认知研究

介绍实景地图的概念,讨论实景地图的空间认知过程和空间认知效果。实景地图遵循地图空间认知的一般过程,但其"亲历式"的感知过程符合人类视觉和记忆习惯。实景地图对位置认知效果较差,对方向认知效果一般,对距离、对象认知效果较好。与二维电子地图和虚拟地理环境相比,实景地图在真实性、信息量、感知度方面存在优势,而在视角和空间感方面劣势明显。