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101.
A.F. Mastryukov 《Russian Geology and Geophysics》2011,52(9):1035-1042
A spectral method for modeling high-frequency electromagnetic waves in axisymmetric geometry is proposed.The method is based on the expansion of the solutions of Maxwell’s equations in Laguerre functions in the time region.The spectral method is used to solve Maxwell’s equations for both 2D media and stratified media. In the case of stratified media, a Fourier–Bessel expansion in the radial variable is used. The effectiveness of the spectral and finite-difference methods is compared. Harmonic solutions and solitary solutions by the Laguerre method are considered, and the dynamics of monochromatic and broadband electromagnetic pulses are examined. 相似文献
102.
《Geomechanics and Geoengineering》2013,8(1):13-25
Electrokinetic flows include the migration of fluid, chemicals, fine particles, bacteria, and electrons through a soil–fluid–chemical system driven by an externally applied direct-current (d.c.) electric field. The promising potential of electrokinetic remediation of contaminated fine-grained soils has stimulated recent interest in the study of electrokinetic flow processes, in particular the impact of a prolonged application of a d.c. electric field on fine-grained soils. The results of a bench-scale laboratory experimental investigation on some of the fundamental aspects of prolonged electrokinetic flows in kaolinites, including gas generation rates at power electrodes, electrochemical behaviour of the soil–fluid–chemical system, time variation of electric current intensity flowing through the soil, pH gradient development in the soil, effects of reservoir chemistry on electro-osmotic fluid volume flow rate and flow direction through the soil, time variation of electro-osmotic volume flow rate, and energy requirements per unit volume of fluid transported, are presented in this paper. Effects of soil type and pore fluid chemistry on these aspects were also studied. 相似文献
103.
104.
Development of technologies for site characterization has grown at a faster pace compared to the development of decision-making methods required for the assimilation of inferences they generate. In the case of geophysical surveying, such dephase adds to the dependency on the use of expert's judgment in the interpretation of geophysical mappings. A systematic assimilation of this type of geo-surveying evidence is required, in particular for the integration of spatial geomorphological information (i.e., stratigraphy), characterized from different geophysical methods. This paper presents a methodology to address this challenge by the use of a probabilistic approach. A set of synthetic geophysical mappings are used to illustrate the applicability of the proposed methodology and its potential extrapolation to other scientific imaging disciplines. 相似文献
105.
The planet Mars lacks, today, a planetary, dynamic magnetic field, but strong, intense, localized magnetic fields of lithospheric origin, one to two orders of magnitude larger than the terrestrial lithospheric field, are present. This lithospheric magnetic field is the result of magnetization processes in the presence of a magnetic dynamo and of demagnetization processes after the dynamo shutdown, such as impact or volcanoes. This crude scenario can be more accurately specified by interpreting global and local models of the current magnetic field of Mars. Some specific areas are studied, including the intensely magnetized Terra Sirenum, as well as the magnetic anomaly associated with Apollinaris Patera. Magnetic minerals could be of primary and/or secondary origin; this latter would imply an early hydration of a basaltic crust. A scenario, in which Mars experienced a major polar wander due to the Tharsis bulge, prior to the cessation of its dynamo, is proposed and discussed. 相似文献
106.
P. V. Kulkarni 《Journal of Earth System Science》1983,92(3):247-253
Tropical airglow work during the last few years is reviewed. Airglow instrumentation is becoming more complex. Some of these
sophisticated airglow experiments giving important information about the upper atmosphere such as ionospheric F region electron
density, height of maximum electron density, dynamics of and irregularities in the F region, mesospheric neutral temperature
and its variation, dynamics of mesospheric, etc. are mentioned. At the end some problems which could be tackled in near future
with airglow techniques have been suggested.
Invited Review paper, Commission 21, IAU, Patras, Greece, August, 1982. 相似文献
107.
Gao-Feng Zhao Qiuyue Yin Adrian R. Russell Yingchun Li Wei Wu Qin Li 《国际地质力学数值与分析法杂志》2019,43(1):166-182
The bonded discrete element model (DEM) is a numerical tool that is becoming widely used when studying fracturing, fragmentation, and failure of solids in various disciplines. However, its abilities to solve elastic problems are usually overlooked. In this work, the main features of the 2D bonded DEM which influence Poisson's ratio and Young's modulus, and accuracy when solving elastic boundary value problems, are investigated. Outputs of numerical simulations using the 2D bonded DEM, the finite element method, a hyper elasticity analysis, and the distinct lattice spring model (DLSM) are compared in the investigation. It is shown that a shear interaction (local) factor and a geometric (global) factor are two essential elements for the 2D bonded DEM to reproduce a full range of Poisson's ratios. It is also found that the 2D bonded DEM might be unable to reproduce the correct displacements for elastic boundary value problems when the represented Poisson's ratio is close to 0.5 or the long-range interaction is considered. In addition, an analytical relationship between the shear stiffness ratio and the Poisson's ratio, derived from a hyper elasticity analysis and applicable to discontinuum-based models, provides good agreement with outputs from the 2D bonded DEM and DLSM. Finally, it is shown that the selection of elastic parameters used the 2D bonded DEM has a significant effect on fracturing and fragment patterns of solids. 相似文献
108.
Jean Ferrandini Michelle Ferrandini Philippe Rossi Brengre Savary-Sismondini 《Comptes Rendus Geoscience》2010,342(12):921-929
Priabonian age is highlighted for the first time in Corsica in the Venaco Formation using the presence of specific microfauna (in particular some representatives of Turborotalia cerroazulensis lineage). This silicoclastic formation is mainly represented by coarse facies. It is composed of three members from south to north and from oldest towards youngest: member of Uboli, Cardo and Orsu. The sedimentologic analysis reveals a gravity depositional environment, involving different type of currents. Sedimentologic and chronologic characteristics make the Venaco Formation and the Annot Formation (p.p.) equivalent. Dating the Venaco Fm. brings confirmation that the green schist metamorphism of the Variscan batholith and the related deformation are from the pre-Priabonian period. 相似文献
109.
一维大变形主、次固结耦合新模型 总被引:1,自引:1,他引:1
针对传统一维大变形固结理论不能考虑土体次固结变形的缺点,在连续介质力学有限变形理论和土力学固结理论基础上,提出了全新的一维大变形主、次固结耦合模型。该模型采用超静孔压为控制变量,可以分别表述为欧拉坐标、拉格朗日坐标和固相体积坐标等三种形式,其中均可以显式地反映出土体重度变化、固相速度、地表沉降速度、地下水位变化、荷载变化和次固结等6个因素的影响。在不同简化条件下,新模型可以分别退化为以往学者提出的相关模型。当不考虑次固结效应时,新模型与经典的Gibson大变形固结模型完全等价。从便于工程应用的角度而言,新模型中仅考虑次固结和外荷载变化的退化形式更便于求解,可作为一种供参考的实用模型。 相似文献
110.