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81.
Image processing of 2D resistivity data for imaging faults 总被引:6,自引:0,他引:6
F. Nguyen S. Garambois D. Jongmans E. Pirard M.H. Loke 《Journal of Applied Geophysics》2005,57(4):260-277
A methodology to locate automatically limits or boundaries between different geological bodies in 2D electrical tomography is proposed, using a crest line extraction process in gradient images. This method is applied on several synthetic models and on field data set acquired on three experimental sites during the European project PALEOSIS where trenches were dug. The results presented in this work are valid for electrical tomographies data collected with a Wenner-alpha array and computed with an l1 norm (blocky inversion) as optimization method. For the synthetic cases, three geometric contexts are modelled: a vertical and a dipping fault juxtaposing two different geological formations and a step-like structure. A superficial layer can cover each geological structure. In these three situations, the method locates the synthetic faults and layer boundaries, and determines fault displacement but with several limitations. The estimated fault positions correlate exactly with the synthetic ones if a conductive (or no superficial) layer overlies the studied structure. When a resistive layer with a thickness of 6 m covers the model, faults are positioned with a maximum error of 1 m. Moreover, when a resistive and/or a thick top layer is present, the resolution significantly decreases for the fault displacement estimation (error up to 150%). The tests with the synthetic models for surveys using the Wenner-alpha array indicate that the proposed methodology is best suited to vertical and horizontal contacts. Application of the methodology to real data sets shows that a lateral resistivity contrast of 1:5–1:10 leads to exact faults location. A fault contact with a resistivity contrast of 1:0.75 and overlaid by a resistive layer with a thickness of 1 m gives an error location ranging from 1 to 3 m. Moreover, no result is obtained for a contact with very low contrasts (1:0.85) overlaid by a resistive soil. The method shows poor results when vertical gradients are greater than horizontal ones. This kind of image processing technique should be systematically used for improving the objectiveness of tomography interpretation when looking for limits between geological objects. 相似文献
82.
J. Plomerova L. Vecsey V. Babuska M. Granet U. Achauer 《Studia Geophysica et Geodaetica》2005,49(4):541-560
We present results of an array study of seismic anisotropy beneath the Bohemian Massif (BM) showing distinct lateral and directional
variations of the fast shear-wave polarization and split-delay time consistent with variations in the P-residual spheres,
in which directional means of relative residuals are subtracted. Our analysis of the S- and P-wave anisotropy suggests that
the mantle lithosphere of the BM consists of at least three large domains with different orientation of the large-scale fabric
separated by sutures cutting most likely the whole lithosphere. Boundaries of the units are characterised by a null or small
shear-wave splitting, as well as by smaller values in the P-residual spheres. We present self-consistent 3D anisotropic models
of the lithosphere domains of the BM resulting from joint inversion of anisotropic parameters searching for a 3D orientation
of mantle fabric. While in the Saxothuringian and Sudetes parts of the BM the (a, c) foliations dip prevailingly to the N-NW,
they dip to the S and SW in the southern and eastern parts of the Moldanubian. 相似文献
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87.
Multi-dimensional Seismic Response Analysis of Base-Isolated Frame Structure with 3D Isolator 总被引:1,自引:0,他引:1
XiongShishu HuangLiting ChenJinfeng SuJingsu 《中国地质大学学报(英文版)》2005,16(1):66-71,78
INTRODUCTIONAs a new and effective method for withstandingthe horizontal component of earthquake motion on abuilding structure, the base isolation technique hascome to the engineering application phase ( Hu,1988). However, for some important buildings andfoundation facilities in an earthquake region, it is im portant to consider the effects of 3D aseismatic analy sis, including the vertical component, due to themulti dimensional characteristics of earthquakes (Suand … 相似文献
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基于深度学习的地震数据噪声压制方法是当前地震数据去噪处理的重要方向。深度学习方法突破了传统滤波处理的局限,在对常规地震数据的噪声压制中表现出效率高、信噪分离效果好的特点。但针对深部弱有效反射数据,当前的深度学习方法特征提取能力有限,难以取得较好的去噪效果。笔者等结合深反射地震数据特点,针对当前深度学习噪声压制方法在特征提取及对数据集依赖上的局限,提出了基于注意力循环生成对抗网络(Attention Cycle- Consistent Generative Adversarial Networks,A- CGAN)的深反射地震数据随机噪声压制方法。借助循环一致生成对抗网络(Cycle- Consistent Generative Adversarial Networks,Cycle- GAN)的域映射思想,降低对数据集的要求。为了构建适用于深反射地震数据的去噪网络,从3个方面对Cycle- GAN进行改进:在Cycle- GAN的生成器(去噪器)中加入残差结构和注意力机制,用于加深网络深度和提高其特征提取能力;在Cycle- GAN的鉴别器中使用块判决,提高鉴别精度和准确度;在损失函数部分加入感知一致性损失函数,提升网络模型恢复纹理细节信息的能力。通过合成地震数据和实际深反射地震数据测试,验证了优化算法的有效性,体现了良好的应用价值。 相似文献
90.
徐剑平 《测绘与空间地理信息》2008,31(4)
目前,地理信息数据加工产业在管理方式方法上,存在着先进的生产力与不先进的管理方式相矛盾的问题.如何有效管理"管理信息流"等诸多管理问题,是一个无法回避和必须解决的课题.本文基于开发实践,介绍系统的技术路线、系统功能、系统特点以及系统数据库的设计.随着本系统的不断推广应用,一定能为地理信息数据加工行业的生产管理开拓新的模式,提供有力的支撑. 相似文献