Three-dimensional magnetotelluric inversion using conjugate gradients   总被引：22，自引：0，他引：22  

Randall L. Mackie  Theodore R. Madden 《Geophysical Journal International》1993,115(1):215-229

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Periodic pumping tests     

Jörg Renner  Mareike Messar 《Geophysical Journal International》2006,167(1):479-493

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井地电法的准解析近似三维反演研究   总被引：1，自引：0，他引：1  

王志刚  何展翔  刘海樱 《应用地球物理》2006,3(3):141-147

研究复杂地电模型上的井地电法三维反演一直是一个具有挑战性的课题。本文在准解析近似和重加权正则化的共轭梯度法的基础上,用visualFortran6.5开发了井地电法三维准解析近似反演程序。反演过程中的正演和Frechet导数矩阵计算都应用准解析近似大大提高了计算的速度。通过理论模型的合成数据反演试算,说明基于准解析近似法和加权正则化的共轭梯度法的井地电法三维反演程序有着计算速度快,反演精度高等特点。  相似文献   

Characterisation of Tensile Damage in Rock Samples Induced by Different Stress Paths     

Patrick Ganne  André Vervoort 《Pure and Applied Geophysics》2006,163(10):2153-2170

Cracks, induced by different stress states, are studied systematically on thin slices of crinoidal limestone samples. Samples damaged by tension are compared to samples in which first damage is induced by compressive stresses, followed by tensile stresses. To quantify the effect of the compressive stresses, samples only damaged by compression are also studied. The tensile stresses cause the occurrence of an intergranular crack. When the sample is first damaged by compressive stresses, former induced damage influences the growth of this crack. It results in an intergranular crack with a zigzag profile. The average orientation of the intergranular crack is, however, the same as in the samples damaged by tension only.  相似文献   

集成BP网络在城市地下水水质评价中的应用     

李云辉 《地下水》2006,28(5):36-37

为了克服传统BP网络的不足,发挥共轭梯度法和梯度下降法各自的优势,本文介绍了在城市地下水水质评价模型中采用集成BP网络、用共轭梯度法和梯度下降法相结合的混合算法来训练网络的方法.通过实例表明,将此网络模型应用于城市地下水水质评价是有效的、可行的.  相似文献   

大型方程组快速解算方法研究     

徐天河 《测绘科学与工程》2006,26(1):1-4

本文研究了大型方程组的解算方法，给出了改进的共轭梯度算法和预条件共轭梯度算法，推导了相应的计算公式。对各种算法的计算效率进行了比较，结果表明，改进的共轭梯度法和预条件共轭梯度法能有效提高大型方程组的解算效率，其缺点是不能精确给出参数估值的验后协方差矩阵。  相似文献   

Relationships between volcanic patterns and neotectonics in Eastern Anatolia from analysis of satellite images and DEM     

. Ad&#x;yaman  J. Chorowicz  O. Kse 《Journal of Volcanology and Geothermal Research》1998,85(1-4)

The late Neogene to Quaternary volcanism in Eastern Anatolia is related to the Arabia–Eurasia convergence but a clear deformation pattern has not yet been established in this region. We have used the distribution and shape of volcanoes and fault geometry as indicators of the tectonic regime. Volcanic edifices and related faults were analyzed in vertical view using SAR–ERS, Spot images and a Digital Elevation Model (DEM). In several places, adjacent volcanoes that form linear clusters or elongated volcanoes are clearly rooted on vertical tension fractures. These are compatible with horizontal σ₃ striking 90°N, associated with σ₁ horizontal (strike-slip regime) or vertical (extensional regime). We mapped the recent faults that are directly associated to volcanoes. Volcanic vents are related to tail-crack, horsetail or releasing bend structures. In this work, it has been possible to define the ESE-striking, 270-km-long Tutak–Hamur–Çaldiran fault that forms a releasing bend testifying to right-lateral motion. Extension is well documented for few places but no recent fold has been observed. Since 8 Ma, the tectonic system is principally strike-slip. Most of the tension fractures being 2 to 10 km in length, so we infer that they affect only part of the crust. Most strike-slip fault zones are of several tens to a few hundred kilometers long and thus not of lithospheric scale. Therefore, the channels used by the magma to reach the surface are crustal structures.  相似文献   

Characteristics and origins of coal cleat: A review   总被引：7，自引：0，他引：7  

S. E. Laubach  R. A. Marrett  J. E. Olson  A. R. Scott 《International Journal of Coal Geology》1998,35(1-4)

Cleats are natural opening-mode fractures in coal beds. They account for most of the permeability and much of the porosity of coalbed gas reservoirs and can have a significant effect on the success of engineering procedures such as cavity stimulations. Because permeability and stimulation success are commonly limiting factors in gas well performance, knowledge of cleat characteristics and origins is essential for successful exploration and production. Although the coal–cleat literature spans at least 160 years, mining issues have been the principal focus, and quantitative data are almost exclusively limited to orientation and spacing information. Few data are available on apertures, heights, lengths, connectivity, and the relation of cleat formation to diagenesis, characteristics that are critical to permeability. Moreover, recent studies of cleat orientation patterns and fracture style suggest that new investigations of even these well-studied parameters can yield insight into coal permeability. More effective predictions of cleat patterns will come from advances in understanding cleat origins. Although cleat formation has been speculatively attributed to diagenetic and/or tectonic processes, a viable mechanical process for creating cleats has yet to be demonstrated. Progress in this area may come from recent developments in fracture mechanics and in coal geochemistry.  相似文献   

吉林省夹皮沟金矿成因研究   总被引：1，自引：0，他引：1  

李碧乐  金巍 《世界地质》1998,17(1):22-25

吉林省夹皮沟金矿区金矿赋存在夹皮沟北西向韧性带内,控矿构造为叠加在韧性剪切带之上的脆性构造。中生代中酸性脉岩为成矿期脉岩,且与黄泥河花岗岩岩基有着密切的成因联系。成矿物质主要来自岩浆分异,金丰度值高的暗色岩类提供部分矿质。  相似文献   

腾冲——勐海共轭地震构造带   总被引：2，自引：0，他引：2  

张四昌  刁桂苓 《华北地震科学》1996,14(1):11-18

使用地震和地质资料的综合分析方法研究了腾冲一勐海地区地震破裂特征,结果认为:本区存在长400km,宽45km的地震构造带,它是由一条长400km,宽25km的NNW向右旋剪切带为主干和几条NE-NEE向左旋走滑断裂变切而成的共轭地震构造带.带内地震具有线性排列和统一的周期性活动.  相似文献