三维地震数据的体绘制   总被引：5，自引：3，他引：5  

雷兵  马在田 《物探化探计算技术》2004,26(3):206-210

体视化技术是三维地震数据浏览、分析和解释的有效工具。对于理解地震数据中蕴涵的结构和地层学信息，体视化比使用一组二维切片表示三维数据更自然。解释人员可以突出数据体中某些特定的区域体，以利于更好地理解它们的空间分布，也可以添加合并两个或者更多的，具有不同地震特征的体积区域。医学应用方面的一些体视化方法不能直接应用于地震数据方面．必须考虑地震数据自身特点才能使可视化成功实现。通过分析三维地震数据的特点进而得出实现三维地震数据体视化算法的基本方法，并对实际数据进行了实验。  相似文献   

类比合成方法在干旱区内陆河径流量预报中的应用     

陈果  尚松浩  雷志栋 《干旱区地理》2004,27(3):287-292

类比合成算法是一种多维模式搜索法，它具有适用范围广、对资料要求低等优点，可用于单变量及多变量时间序列的延拓预测。通过介绍类比合成算法，并把它应用于塔里木河源流叶尔羌河、和田河年、月径流量预报，其中重点分析了模式长度和合成预报的模式个数等因素对预报结果的影响。通过实测径流资料对预报结果的检验和分析表明，类比合成算法可以较好地挖掘径流序列中隐藏的信息，在中长期水文预报中是一种行之有效的计算方法。  相似文献   

Strains of scattering of near-field of a point source     

M. D. Sharma 《Journal of Earth System Science》2004,113(2):247-257

Three dimensional scattering of near-field is studied for dilatation and rotation in the time domain. The perturbation method is applied to solve the equation of motion for the first order scattering from a weak inhomogeneity in an otherwise homogeneous medium. The inhomogeneity is assumed close enough to the point source so that the near-field intermediate wave is dominating over the far-field sphericalP andS pulses. The integral expressions are derived to relate dilatation and rotation of scattering to the radial fluctuations of velocities and density in the inhomogeneity. These integrals are solved to calculate the strains of scattering from (a part of) an inhomogeneous spherical shell of arbitrary curvature. Variable curvature may allow the shape of inhomogeneity volume element to change uniformly from spherical to rectangular. Rotation of scattering from a spherical shell is independent ofP wave velocity inhomogeneity. Dilatation of scattering does not involveS wave velocity inhomogeneity but its gradient. The back scattering results are obtained as a special case. Strains are computed numerically, for hypothetical models to study the effects of various parameters viz., velocity inhomogeneity, distance of source from inhomogeneity and from receiver, and thickness of inhomogeneity. The curvature of the spherical shell is varied to study the effects of the shape of inhomogeneous volume element on scattering.  相似文献   

Mixed Primal–Dual Method for Nuclear Waste Disposal Far Field Simulation     

David Trujillo 《Computational Geosciences》2004,8(2):173-185

A mixed finite volume method is applied in order to simulate a simplified Far Field model. We show how this method can be adapted to both the elliptic and the convection–diffusion equations describing the water flow and the variations of the concentration of the radioactive element respectively. For the water flow problem, we justify an a posteriori error estimator. Finally, we present some numerical results.  相似文献   

基于三角形折叠的连续多分辨率LOD算法   总被引：8，自引：3，他引：8  

周杨姬渊  蓝朝桢徐青 《测绘学院学报》2004,21(4):279-281,285

LOD技术是从软件方面提高大范围场景3维渲染速度的有效手段之一。文中在基于三角形折叠的LOD简化算法的基础上，针对在3维景观绘制中模型数据需实时简化的特点，提出了一种基于三角形折叠的连续LOD算法，即预先对模型的几何数据进行简化预处理，并记录每一步的简化操作，以便于在3维景观绘制时，根据要求实时显示不同分辨率的模型数据。最后通过实验数据验证了该算法的正确性和实用性。  相似文献   

中国西部积雪微波遥感监测     

曹梅盛  李培基 《山地学报》1994,(4)

用１９７８─１９８７年多通过微波扫描辐射计（ＳＭＭＲ）所获取的地表微波亮温及亮温－雪深区域订正反演算式，计算了１００°Ｅ以西中国境内年与季的平均雪量和雪盖率，以及它们的年际变化，阐明了积雪时空的变化。所取得的高原及高山低山积雪监测结果，为当地积雪资源的开发利用提供了可靠依据。  相似文献   

Grain-size variation of tephra derived from volcanic umbrella clouds     

Takehiro Koyaguchi 《Bulletin of Volcanology》1994,56(1):1-9

The relationships among the thickness and grain-size of tephra-fall deposits and the volumetric flow rate of their source umbrella clouds are analytically obtained. The logarithm of the ratio of the probability distribution function based on grain size (ln R _f) in fall deposits at two localities from the vent (r ₁ and r ₂, respectively) has a linear relationship with the particle-settling velocity, v, as: where Q is the volumetric flow rate of the umbrella cloud and A is a constant for a given pair of localities. The volumetric flow rate of the umbrella cloud can be estimated from granulometric data using this formula. Generally, the thickness–distance relationship of tephra-fall deposits depends on the initial grain-size distribution and the volumetric flow rate of the umbrella cloud. The empirical relationship of the exponential thinning behaviour can be extrapolated towards infinite distance only for a specific initial grain size which is similar to a log-normal distribution with σ _φ=2.5, otherwise it holds only in a limited range of distances. In applying these results to the 1991 eruption of Mt. Pinatubo, it is shown that the volumetric flow rate of the umbrella cloud during the climactic phase of 15 June was approximately 5×10¹⁰ m³/s, which is fairly consistent with the expansion rate of the umbrella cloud observed in the satellite images. Received March 20, 1993/Accepted September 11, 1993  相似文献   

变形岩石的体积损失和流体－岩石相互反应     

杨新岳 《地质科技情报》1994,(1)

介绍了近年来国外在研究压溶作用导致的变形岩石体积损失和变形过程中流体作用的主要成果。包括如下几方面：运用有限应变测量方法对压溶变形作用进行定量分析；不同变形域之间化学成分的分异，以及流体传质作用（ｍａｓｓｔｒａｎｓｐｏｒｔ）的规律；流体－岩石相互反应的显微构造、显微化学判据；运用稳定同位素体系研究流体、岩石反应的同位素平衡关系及变形变质过程中的水／岩比率。  相似文献   

泡沫钻进的参数选择     

柯扬船 《吉林大学学报(地球科学版)》1993,(4)

泡沫钻进的灌注压力是关键参数。本文引入参数R_o后,使压力公式简化、明显、直观,是系统效应的结果。为现场直观参考及计算机化找到了依据。R_o的引入改变了常规流型判别的雷诺计算法。  相似文献   

Measuring the geometry of a developing scour hole in clear-water conditions using underwater sonar scanning     

《国际泥沙研究》2020,35(1):105-114

A novel scanning technique using a rotating-head sonar profiler attached to a slider mechanism is presented as a means to directly measure the complex erosion and deposition features of local scour holes developing in clear-water conditions around vertical cylinders mimicking bridge piers.Extensive validation shows that the method produces high-density elevation surfaces to within≌1.5±2 mm accuracy in a quasi-non-invasive manner.This equates to 0.5±0.7% relative to the flow depth which sonar resolution is well known to scale with.Experimental data from three trials using different cylinder diameters indicate that monitoring of the entire scour hole over time(instead of only the maximum depth as is commonly done in laboratory experiments) can reveal important information about local scour evolution.In particular,results show that the scour-hole volume scales with the maximum scour depth cubed(V_(OL)-y_S~3) through three linear regimes.The transition to the third linear regime was found to represent a step change in the scour evolution process.Following the recent theoretical framework proposed by Manes and Brocchini(2015),this change,termed the crossover point,was interpreted as the point where the production of turbulent kinetic energy plateaus which corresponds to a stabilization in the erosive power of the horseshoe vortex.Scour development beyond the crossover point is characterised by a significant reduction in the rate of volumetric scour,relative to the steadily-increasing maximum scour depth.This overall reduction in volume-development is attributed to a balance between erosion from in-front of the pier and deposition around the sides using topography analysis.It is speculated that the existence of the crossover point may help to identify the characteristic length and time scales describing the evolution of local scour,which may be used for modeling purposes.  相似文献