Inversion of multimode surface wave data: evidence for sub-lithospheric anisotropy     

Jean-Jacques Lévêque  Michel Cara 《Geophysical Journal International》1985,83(3):753-773

Summary. Multiparameter inversions of multimode dispersion data are performed for two large regions: the Pacific Ocean and North America. Anisotropy is taken into account by considering transversely isotropic structures with a vertical axis of symmetry. Two fundamental questions are studied in detail: (1) how to make the inverted models consistent when using different sets of parameters, (2) what is the significance of transversely isotropic inversion for the actual Earth's structure? It is proved that full consistency of the inverted models can be achieved by properly taking into account some a priori informations on the model and it is shown that the use of transversely isotropic models with vertical axis of symmetry does not cause severe limitations when interpreting the data. The models we have obtained are discussed in the light of these investigations. Considering an olivine-rich upper mantle, we make a tentative interpretation of these models in terms of preferred orientation of the a -axis of the crystals in one fixed horizontal direction.  相似文献   

Prediction of lateral variability in fracture intensity using multicomponent shear-wave surface seismic as a precursor to horizontal drilling in the Austin Chalk   总被引：1，自引：0，他引：1  

Michael C. Mueller 《Geophysical Journal International》1991,107(3):409-415

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试论城市地貌环境与城市道路系统的关系^*——以四川省几个城市为例   总被引：5，自引：0，他引：5  

刁承泰 《地理研究》1991,10(1):95-102

本文分析了城市地貌环境对城市道路系统的影响,认为地貌过程不仅影响了城市道路的建设和管理,而且是城市道路系统布局和发展的重要控制因素。以四川省几个城市为例,分析了山地城市、丘陵城市和平原城市道路系统的不同特点。  相似文献   

案例推理的地学应用背景和方法   总被引：3，自引：1，他引：2  

杜云艳周成虎  邵全琴苏奋振史忠植  叶施仁 《地球信息科学学报》2002,4(1):98-103

案例推理 (CBR)研究 ,是人类认知的一种合理性模型 ,接近于人类认识、解决问题最原始的思维方式 ,具有在无法获取机理模型、确定规则或统计模型时 ,采用简单的历史相似性推理实现问题的定量求解和预测 ,成为人工智能领域近年来的研究热点。  相似文献   

Miniature gravity corer for recovering short sediment cores   总被引：12，自引：0，他引：12  

John R. Glew 《Journal of Paleolimnology》1991,5(3):285-287

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The second order characteristic condition for plastic flow     

Graham Weir  Roger Young 《国际地质力学数值与分析法杂志》2003,27(15):1299-1316

In this paper the second order characteristic (discontinuous bifurcation) condition is derived for the granular flow (fully plastic) equations. This second order bifurcation equation is shown to be formally identical to the first order localization requirement during steady elastoplastic deformation provided the elastic compliance tensor is substituted for the product of the plastic multiplier with the flow Hessian. For isotropic yield and flow functions the invariant form of the characteristic condition is given in detail, as well as an alternative expression in adapted co‐ordinates. The characteristic condition can be regarded as defining a hardening function which is maximized to identify the critical angles. When the method is applied to 3D Coulomb flow, Mohr's 3D fracture plane conditions are obtained uniquely. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Long-chain alkenones and U₃₇′ variability along a south–north transect in the Western Pacific Ocean     

Ilhem Bentaleb  Michel Fontugne  Luc Beaufort 《Global and Planetary Change》2002,34(3-4)

In this paper, we present 50 surface water samples collected during the IMAGES III cruise (June–July 1997) along a transect from New Zealand to the China Sea (42°S–178°E, 21°N–120°E) covering a temperature range from 13.3 to 30.4 °C. A very worthwhile aspect of this study is a coupling of both biomarker (alkenone) and coccolithophorid counting. We show that the U₃₇^k′–temperature relationship is very similar to the Prahl et al. [Geochim. Cosmochim. Acta 52 (1988) 2203] culture calibration and to the global core top calibration of Müller et al. [Geochim. Cosmochim. Acta 62 (1998) 1757]. However, in the warmest surface waters of the Western Pacific ocean (>26.4 °C) where Gephyrocapsa oceanica is likely the most widespread species, the associated U₃₇^k′ has a constant value of 1.0. The consequence is that above this temperature threshold, U₃₇^k′ cannot be used as an accurate paleothermometer.  相似文献   

Modelling enhanced density shells in the circumstellar envelope of IRC +10216     

J. M. Brown  T. J. Millar † 《Monthly notices of the Royal Astronomical Society》2003,339(4):1041-1047

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Point source detection using the Spherical Mexican Hat Wavelet on simulated all-sky Planck maps     

P. Vielva  E. Martínez-González  J. E. Gallegos  L. Toffolatti  J. L. Sanz 《Monthly notices of the Royal Astronomical Society》2003,344(1):89-104

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Light-curve classification in massive variability surveys – I. Microlensing     

Vasily Belokurov  N. Wyn Evans  Yann Le Du 《Monthly notices of the Royal Astronomical Society》2003,341(4):1373-1384

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