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941.
高速网上3维海量地形数据的实时交互浏览的实现 总被引:13,自引:2,他引:13
针对高速网上3维海量地形数据传输和显示特点,提出了一套海量地形数据处理、存储方法,包括数据的预处理和数据的存储结构,数据存储有利于高速网络访问;并根据人的视觉生理特征,提出了一种多分辨率地形表示模板形成,较好地处理了实时交互游览地形的真实感和巨大数据需求之间的冲突。设计了一种适合网络实时传输海量地形数据的传输协议,使系统充分利用网络带宽同时又不浪费带宽。通过在中国高速互联试验网络NFSCNet上的大量演示,表明所提出的技术方案是切实可行的,证明了高速网对3维海量地形实时交互浏览的必要性和可行性。 相似文献
942.
We use a thin sheet approach to investigate the effects induced by the Alpine collision on the deformation and regional stress in northern Europe, with special emphasis on the NE German Basin. Here new seismic crustal studies indicate a flexural-type basin, which may have been induced by compressive forces transmitted from the south, due to the Alpine orogeny. Finite-element techniques are used to solve the equations for the deformation of a continuum described by a linear creep rheology and a spatial resolution of about 0.5°. The model has been constrained by stress and seismic data. We show that a relatively strong lithosphere below the northern margin of the German Basin, at the transition with the Baltic Shield, may explain the characteristic regional stress field, in particular the fan-like pattern which is observed within the region. Furthermore, the predicted strain rate pattern resembles the seismically recognizable undeformed area of the North German Basin. 相似文献
943.
944.
Man–computer interactive method on cloud classification based on bispectral satellite imagery 总被引:5,自引:0,他引:5
A bispectral cloud classification method based on man-computer interactive way, i.e. a unit feature space clasification method (UFSCM), has been presented in this paper. Apart from land and water, six types of clouds including cumulonimbus, multilayer cloud system, thin / think cirrus, middle and low level clouds are recognized. The method has been tested by using more than two hundred samples, with total accuracy reaching 87.1%. 相似文献
945.
946.
本文讨论了应用NOAA-AVHRR数字图像研究植被季相变化和进行植被分类的多时相方法。对生长季节的各时相植被指数VI图像进行图像分割,可揭示植被绿锋的进退和季相变化及其在空间上的表现。对多时相的植被指数VI图像进行主成分变换,据第一主成分的直方图各特征峰的形状和位置进行图像分割,可获得植被景观图,这一结果与现行的植被分布图相当一致。 相似文献
947.
948.
L. Sirovich 《Soil Dynamics and Earthquake Engineering》1997,16(6):353-362
Recent tests on a series of earthquakes in California and Nevada suggest that in some regions the approximate shapes of the territories with equal earthquake-induced damage (expressed in terms of macroseismic intensity) could be synthetically traced out with a simple formula. This formula takes into account some gross features of the source: depth and length, unilateral or bilateral rupture, radiation patterns, rupture velocity, and directivity. Having been formulated on an empirical basis, the formula is however compatible with the so-called asymptotic approach, in which the far-field component of the Green's function is used. This paper presents the synthetic isoseismals of the earthquakes at Cedar Mountain, Nevada, 1932; Fairview Peak-Dixie Valley, Nevada, 1954; and Coalinga, California, 1983. An overall consistency, from acceptable to remarkable, between the observed intensity patterns and the synthetically back-predicted intensity has been obtained for them. Where the detailed modelling techniques available today are inapplicable, due to insufficient information on the features of the seismic sources, or to save time and money, the new formula may be utilizable for improving seismic hazard calculations.The formula was also used inversely for back-predicting geometric-kinematic parameters of the Coalinga 1983 earthquake from macroseismic maps. This gave characteristics for its source which are in good agreement with the majority of data inferred from modelling and from analyzing modern instrumental recordings. This striking result opens new perspectives in retrieving information on the source of ancient earthquakes for which only macroseismic information is available. 相似文献
949.
S. Balassanian S. Nazaretian A. Avanessian A. Arakelian V. Igumnov M. Badalian A. Martirossian V. Ambartsumian A. Tovmassian 《Natural Hazards》1997,15(2-3):231-249
In the present work a new, deterministic, seismic zonation map for the territory of Armenia is presented. It has been compiled on the basis of the newest seismological, geological and geophisical data. Creation of the map included: determination of a seismic hazard area for the territory of Armenia; compilation of a map of active faults; identification of active blocks; identification of seismic source zones; calculation of a seismic effect from the seismic source zones (SSZs). Seismic effect on the Earth's surface from the singled out SSZs is calculated in the form of an intensity of seismic influences expressed in units of MSK-64 scale, and horizontal soil accelerations expressed in fractions of gravity force acceleration (g). The map compiled will allow comparison between the deterministic model with a probabilistic seismic zonation model for the territory of Armenia (in preparation), in order to analyze the western and eastern standards of seismic hazard assessment on the basis of the same complete data base. 相似文献
950.
内蒙古河套地方性砷中毒区地质环境特征与成因探讨 总被引:1,自引:0,他引:1
论文通过对内蒙古砷中毒病区地质环境调查和防砷改水试验工作。从病区地质环境特征入手,系统分析了构造环境;第四纪地质环境水文地质环境,水化学环境,岩矿地球化学环境和古地理及生物化学环境等诸方面特征,对高砷的地质环境成因进行了探讨.得出十条高砷病区与地质环境之间的成因关系,认为高砷病区的形成与地质环境特征有着密切的成因联系.地方性砷中毒是在特定的地质环境条件下形成的。这对地方性砷中毒的形成、分布及防治具有一定的指导意义,亦为后期防砷改水提供了科学依据。 相似文献