基于强约束Delaunay-TIN的三维地学模拟与可视化

该文以煤层为例,在分析地层底板空间信息特征的基础上,以地层底板等高线为数据源,基于强约束Delau－nay三角形研究含量断层约束的三维地学模拟的数据组织方法,设计地层底板要素的数据结构,并讨论底板各要素的拓扑关系。进而以Delphi和OPGL编程,在CeoMo^3D系统中开发插件,实现了地层底板的3D可视化和基于Voronoi图的地层体积与矿层的储量计算。     

Modélisation du festonnage des barres sableuses d'avant-côte : application à la côte aquitaine,France

Nearshore crescentic bars play a key role in nearshore morphodynamics. These bars are observed all along the Aquitanian Coast, with a mean wavelength of about 700 m. A non-linear stability analysis is undertaken to simulate the development of crescentic patterns. Results show that self-organization mechanism can lead alone to the development of these alongshore rhythmic features. Simulated wavelengths are in agreement with observations on the Aquitanian Coast. To cite this article: B. Castelle et al., C. R. Geoscience 338 (2006).     

Dynamics of coupled human-landscape systems

A preliminary dynamical analysis of landscapes and humans as hierarchical complex systems suggests that strong coupling between the two that spreads to become regionally or globally pervasive should be focused at multi-year to decadal time scales. At these scales, landscape dynamics is dominated by water, sediment and biological routing mediated by fluvial, oceanic, atmospheric processes and human dynamics is dominated by simplifying, profit-maximizing market forces and political action based on projection of economic effect. Also at these scales, landscapes impact humans through patterns of natural disasters and trends such as sea level rise; humans impact landscapes by the effect of economic activity and changes meant to mitigate natural disasters and longer term trends. Based on this analysis, human-landscape coupled systems can be modeled using heterogeneous agents employing prediction models to determine actions to represent the nonlinear behavior of economic and political systems and rule-based routing algorithms to represent landscape processes. A cellular model for the development of New Orleans illustrates this approach, with routing algorithms for river and hurricane-storm surge determining flood extent, five markets (home, labor, hotel, tourism and port services) connecting seven types of economic agents (home buyers/laborers, home developers, hotel owners/ employers, hotel developers, tourists, port services developer and port services owners/employers), building of levees or a river spillway by political agents and damage to homes, hotels or port services within cells determined by the passage or depth of flood waters. The model reproduces historical aspects of New Orleans economic development and levee construction and the filtering of frequent small-scale floods at the expense of large disasters.     

校园三维景观建模及其飞行漫游的实现

三维景观建模技术是地理信息系统的重要发展领域。本文以AUTOCAD格式的施工设计图为基础,利用三维可视地理信息系统软件Imagis2.3,通过数据的预处理、三维建模、纹理映射,建立了福建师范大学新校区理工楼群模型,并就有关技术问题进行了讨论。     

CFD simulation of fine coal segregation and stratification in jigs

The literature review on discrete element (DEM) model analysis of jigging reveals that an idealized fluid behavior is assumed and the damping of the fluid motion across the mineral bed is generally ignored. A microscopic model based on the principles of Computational Fluid Dynamics (CFD) is used to simulate the liquid flow and stratification of coal particles with a wide size range and density distribution in jigging. Fluid motion is calculated by directly solving the Navier–Stokes equations. Coal particles are moved in a Lagrangian frame through the action of forces imposed by the fluid and gravity. Particle effects on fluid motion are fed back at each time step through calculating the velocity disturbance caused by the particle. Particle–particle and particle–wall collisions are also considered. The snapshots of particle configurations for the simulation of stratification in oscillating flow show that the model predicts the macroscopic behavior, such as segregation and stratification, of particles reasonably well.     

Regional landslide-hazard assessment for Seattle, Washington, USA

Landslides are a widespread, frequent, and costly hazard in Seattle and the Puget Sound area of Washington State, USA. Shallow earth slides triggered by heavy rainfall are the most common type of landslide in the area; many transform into debris flows and cause significant property damage or disrupt transportation. Large rotational and translational slides, though less common, also cause serious property damage. The hundreds of landslides that occurred during the winters of 1995–96 and 1996–97 stimulated renewed interest by Puget Sound communities in identifying landslide-prone areas and taking actions to reduce future landslide losses. Informal partnerships between the U.S. Geological Survey (USGS), the City of Seattle, and private consultants are focusing on the problem of identifying and mapping areas of landslide hazard as well as characterizing temporal aspects of the hazard. We have developed GIS-based methods to map the probability of landslide occurrence as well as empirical rainfall thresholds and physically based methods to forecast times of landslide occurrence. Our methods for mapping landslide hazard zones began with field studies and physically based models to assess relative slope stability, including the effects of material properties, seasonal groundwater levels, and rainfall infiltration. We have analyzed the correlation between historic landslide occurrence and relative slope stability to map the degree of landslide hazard. The City of Seattle is using results of the USGS studies in storm preparedness planning for emergency access and response, planning for development or redevelopment of hillsides, and municipal facility planning and prioritization. Methods we have developed could be applied elsewhere to suit local needs and available data.     

Evidence for Triassic salt domes in the Tunisian Atlas from gravity and geological data

Detailed gravity data were analyzed to constrain two controversial geological models of evaporitic structures within the Triassic diapiric zone (Triassic massifs of Jebel Debadib and Ben Gasseur) of the northern Tunisian Atlas. Based on surface observations, two geological models have been used to explain the origin of the Triassic evaporitic bodies: (1) salt dome/diapiric structure or (2) a “salt glacier”. The gravity analysis included the construction of a complete Bouguer gravity anomaly map, horizontal gravity gradient (HGG) map and two and a half-dimensional (2.5D) forward models. The complete Bouguer gravity anomaly map shows a prominent negative anomaly over the Triassic evaporite outcrops. The HGG map showed the location of the lateral density changes along northeast structural trends caused by Triassic/Cretaceous lithological differences. The modeling of the complete Bouguer gravity anomaly data favored the diapiric structure as the origin of the evaporitic bodies. The final gravity model constructed over Jebel Debadib indicates that the Triassic evaporitic bodies are thick and deeply rooted involving a dome/diapiric structure and that the Triassic material has pulled upward the younger sediment cover by halokinesis. Taking in account kinematic models and the regional tectonic events affecting the northern margin of Africa, the above diapirs formed during the reactive to active to passive stages of continental margin evolution with development of sinks. Otherwise, this study shows that modeling of detailed gravity data adds useful constraints on the evolution of salt structures that may have an important impact on petroleum exploration models.     

基于Web的CCGIS浏览器插件的设计与实现

首先介绍了网络3维虚拟现实的发展现状和一般实现方法，结合数码城市GIS软件的研发，提出了基于Web的3D城市模型浏览器插件的3层浏览器／服务器体系结构，然后重点介绍了采用Java和Java 3D实现客户端3维数据在线操作与动态显示和服务器端一体化数据库管理功能的实现方法。该插件能用于Internet上发布3维城市信息，实现3维空间信息的数据共享，并提供给用户一个逼真的、实时的、可交互的虚拟3维城市。最后给出了一个实验例子和几点结论。     

矿床数学—经济模型及其在元江金矿的应用

利用地质统计学的原理和方法，编制出矿床数学－经济模型软件包，它作为一种储量计算和矿床经济评价方法。介绍了该软件包各模块的功能，并以元江金矿应用为例，展示了该软件包的功能及效果。     

油水双相饱和孔隙模型核磁特性理论研究

利用特征函数展开方法，给出了基于扩散效应的核磁共振Bloch控制方程的弛豫模式解表达式, 在此基础上分别给出了水饱和与油水双相饱和孔隙模型的核磁共振特性模拟结果. 结果表明，孔隙流体的核磁弛豫与孔隙大小、孔隙表面弛豫率、孔隙流体的扩散能力以及含油饱和度等有密切的关系. 对于水饱和孔隙，弛豫时间主要由孔隙大小控制. 当孔隙较大时，即使均匀大小孔隙，孔隙流体的弛豫也会表现为多指数弛豫. 而且最小模式弛豫时间与孔隙大小为非线性关系. 对于油水双相饱和孔隙，在孔隙较小时，含油饱和度对弛豫的影响主要表现在弛豫时间随含油饱和度的增加而线性减小；但在孔隙较大时，含油饱和度的增加对弛豫影响表现在两个方面，其一，孔隙水弛豫由多个弛豫模式控制逐渐转变为由最小弛豫模式控制；其二，孔隙水弛豫时间与含油饱和度表现为非线性关系. 对由实际岩芯抽象出的孔隙模型，采用本文获得的理论公式，在油水双相饱和时进行了正反演模拟. 计算结果与已有的实验结果较为一致.