The Experts below are selected from a list of 42735 Experts worldwide ranked by ideXlab platform
Nicolas P. Trégourès - One of the best experts on this subject based on the ideXlab platform.
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Multiple scattering of seismic waves.
Ultrasonics, 2002Co-Authors: Nicolas P. Trégourès, R. Hennino, Celine Lacombe, Nikolai M. Shapiro, Ludovic Margerin, Michel Campillo, B. A. Van TiggelenAbstract:We present theory and numerical simulations to model seismic wave propagation in the Earth Crust. We compare them to observations made in Mexico.
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Quasi Two-dimensional Transfer of Elastic Waves
Physical Review E : Statistical Nonlinear and Soft Matter Physics, 2002Co-Authors: Nicolas P. Trégourès, Bart A. Van TiggelenAbstract:A theory for multiple scattering of elastic waves is presented in a random medium bounded by two ideal free surfaces, whose horizontal size is infinite and whose transverse size is smaller than the mean free path of the waves. This geometry is relevant for seismic wave propagation in the Earth Crust. We derive a time-dependent, quasi-2D radiative transfer equation, that describes the coupling of the eigenmodes of the layer (surface Rayleigh waves, SH waves, and Lamb waves). Expressions are found that relate the small-scale fluctuations to the life time of the modes and to their coupling rates. We discuss a diffusion approximation that simplifies the mathematics of this model significantly, and which should apply at large lapse times. Finally, coherent backscattering is studied within the quasi-2D radiative transfer equation for different source and detection configurations.
B. A. Van Tiggelen - One of the best experts on this subject based on the ideXlab platform.
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Multiple scattering of seismic waves.
Ultrasonics, 2002Co-Authors: Nicolas P. Trégourès, R. Hennino, Celine Lacombe, Nikolai M. Shapiro, Ludovic Margerin, Michel Campillo, B. A. Van TiggelenAbstract:We present theory and numerical simulations to model seismic wave propagation in the Earth Crust. We compare them to observations made in Mexico.
Bart A. Van Tiggelen - One of the best experts on this subject based on the ideXlab platform.
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Quasi Two-dimensional Transfer of Elastic Waves
Physical Review E : Statistical Nonlinear and Soft Matter Physics, 2002Co-Authors: Nicolas P. Trégourès, Bart A. Van TiggelenAbstract:A theory for multiple scattering of elastic waves is presented in a random medium bounded by two ideal free surfaces, whose horizontal size is infinite and whose transverse size is smaller than the mean free path of the waves. This geometry is relevant for seismic wave propagation in the Earth Crust. We derive a time-dependent, quasi-2D radiative transfer equation, that describes the coupling of the eigenmodes of the layer (surface Rayleigh waves, SH waves, and Lamb waves). Expressions are found that relate the small-scale fluctuations to the life time of the modes and to their coupling rates. We discuss a diffusion approximation that simplifies the mathematics of this model significantly, and which should apply at large lapse times. Finally, coherent backscattering is studied within the quasi-2D radiative transfer equation for different source and detection configurations.
Eric Galin - One of the best experts on this subject based on the ideXlab platform.
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Sculpting Mountains: Interactive Terrain Modeling Based on Subsurface Geology
IEEE Transactions on Visualization and Computer Graphics, 2018Co-Authors: Guillaume Cordonnier, Marie-paule Cani, Bedrich Benes, Jean Braun, Eric GalinAbstract:Most mountain ranges are formed by the compression and folding of colliding tectonic plates. Subduction of one plate causes large-scale asymmetry while their layered composition (or stratigraphy) explains the multi-scale folded strata observed on real terrains. We introduce a novel interactive modeling technique to generate visually plausible, large scale terrains that capture these phenomena. Our method draws on both geological knowledge for consistency and on sculpting systems for user interaction. The user is provided hands-on control on the shape and motion of tectonic plates, represented using a new geologically-inspired model for the Earth Crust. The model captures their volume preserving and complex folding behaviors under collision, causing mountains to grow. It generates a volumetric uplift map representing the growth rate of subsurface layers. Erosion and uplift movement are jointly simulated to generate the terrain. The stratigraphy allows us to render folded strata on eroded cliffs. We validated the usability of our sculpting interface through a user study, and compare the visual consistency of the Earth Crust model with geological simulation results and real terrains.
H.-h. Uchida - One of the best experts on this subject based on the ideXlab platform.
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RE-oxide doped alkaline hydrogen storage materials prepared by mechanical activation
Journal of Materials Science, 2004Co-Authors: N Okada, Ryota Genma, Y. Nishi, H.-h. UchidaAbstract:In the hydrogen energy system, hydrogen storage materials are considered to play an important role, such as H_2 storage and transportation media. In case of fuel-cell powered vehicles, storage material with large capacity and light weight are required. Alanates e.g., NaAlH_4, Na_3AlH_6 or Na_2LiAlH_6 have many advantages as hydrogen storage materials, because of their large hydrogen capacity, abundant in the Earth Crust and lower costs, etc. Alanates are, therefore, promising candidates for practical hydrogen transportation media, while investigations on their reaction kinetics with hydrogen are still insufficient. In this study, we prepared Na_2LiAlH_6 samples with different kinds of RE-oxides doped in the course of ball-milling. RE-oxides were used for improving hydrogen reactivity. Drastically improved hydrogen absorption kinetics obtained were discussed using thermodynamic consideration.
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RE-oxide doped alkaline hydrogen storage materials prepared by mechanical activation
Journal of Materials Science, 2004Co-Authors: N Okada, Ryota Genma, Y. Nishi, H.-h. UchidaAbstract:In the hydrogen energy system, hydrogen storage materials are considered to play an important role, such as H_2 storage and transportation media. In case of fuel-cell powered vehicles, storage material with large capacity and light weight are required. Alanates e.g., NaAlH_4, Na_3AlH_6 or Na_2LiAlH_6 have many advantages as hydrogen storage materials, because of their large hydrogen capacity, abundant in the Earth Crust and lower costs, etc. Alanates are, therefore, promising candidates for practical hydrogen transportation media, while investigations on their reaction kinetics with hydrogen are still insufficient. In this study, we prepared Na_2LiAlH_6 samples with different kinds of RE-oxides doped in the course of ball-milling. RE-oxides were used for improving hydrogen reactivity. Drastically improved hydrogen absorption kinetics obtained were discussed using thermodynamic consideration.
