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Ray-based Born approximation
Šachl, Libor ; Klimeš, Luděk (advisor) ; Bulant, Petr (referee)
Title: Ray-based Born approximation Author: Libor Šachl Department: Department of Geophysics Supervisor: RNDr. Luděk Klimeš, DrSc. Supervisor's e-mail address: klimes@seis.karlov.mff.cuni.cz Abstract: One of the aims of this thesis was coding of program grdborn.for for computing the 2D and 3D ray-based Born approximation of the first order in an inhomoge- nous isotropic medium without attenuation. The computation of 3D amplitudes using the 2D Born approximation is based on the correction term, which is de- rived. The program is further used in computing the Born approximation in various models. We test its performance in three simple models. We study the effect of the discretization, the spurious waves introduced by the finite size of the grid etc. In the next step, we focus on the computations in more compli- cated models. We compute the Born seismograms in 2D heterogenous models. We study the diffracted waves, the effects of caustics etc. Keywords: Born approximation, ray theory, velocity model, perturbation 1
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Ray-based Born approximation
Šachl, Libor
Title: Ray-based Born approximation Author: Libor Šachl Department: Department of Geophysics Supervisor: RNDr. Luděk Klimeš, DrSc. Supervisor's e-mail address: klimes@seis.karlov.mff.cuni.cz Abstract: One of the aims of this thesis was coding of program grdborn.for for computing the 2D and 3D ray-based Born approximation of the first order in an inhomoge- nous isotropic medium without attenuation. The computation of 3D amplitudes using the 2D Born approximation is based on the correction term, which is de- rived. The program is further used in computing the Born approximation in various models. We test its performance in three simple models. We study the effect of the discretization, the spurious waves introduced by the finite size of the grid etc. In the next step, we focus on the computations in more compli- cated models. We compute the Born seismograms in 2D heterogenous models. We study the diffracted waves, the effects of caustics etc. Keywords: Born approximation, ray theory, velocity model, perturbation 1
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Modelling of global ocean circulation and ocean-induced magnetic field
Šachl, Libor ; Martinec, Zdeněk (advisor) ; Schindelegger, Michael (referee) ; Toh, Hiroaki (referee)
Title: Modelling of global ocean circulation and ocean-induced magnetic field Author: Libor Šachl Department: Department of geophysics Supervisor: prof. RNDr. Zdeněk Martinec, DrSc., Department of geophysics Abstract: The ocean modelling community commonly use several renown ocean general circulation models (OGCMs) such as NEMO, MOM and FESOM. These models have been developed by research groups for many years, which resulted in complex mathematical and numerical algorithms. There are geophysically rele- vant problems, such as the glacial isostatic adjustment, in which the global ocean plays an important role. Ocean circulation does not need to be modeled extremely complex, but other phenomena such as time changing geometry of ocean domain needs to be considered. Geophysical applications motivated us to develop a new OGCM called LSOMG. The LSOMG model is not meant to substitute the ex- isting OGCMs but to provide a modelling framework for geophysical rather than purely oceanographic applications. LSOMG is a 3-D baroclinic ocean model fully parallelized using the MPI standard. It is forced by atmospheric fluxes (wind stresses, heat fluxes, etc.) but also by tides. The model can be run in a simplified 2-D barotropic version if 3-D effects can be neglected. LSOMG was tested in a series of simplified...
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Ray-based Born approximation
Šachl, Libor
Title: Ray-based Born approximation Author: Libor Šachl Department: Department of Geophysics Supervisor: RNDr. Luděk Klimeš, DrSc. Supervisor's e-mail address: klimes@seis.karlov.mff.cuni.cz Abstract: One of the aims of this thesis was coding of program grdborn.for for computing the 2D and 3D ray-based Born approximation of the first order in an inhomoge- nous isotropic medium without attenuation. The computation of 3D amplitudes using the 2D Born approximation is based on the correction term, which is de- rived. The program is further used in computing the Born approximation in various models. We test its performance in three simple models. We study the effect of the discretization, the spurious waves introduced by the finite size of the grid etc. In the next step, we focus on the computations in more compli- cated models. We compute the Born seismograms in 2D heterogenous models. We study the diffracted waves, the effects of caustics etc. Keywords: Born approximation, ray theory, velocity model, perturbation 1
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Ray-based Born approximation
Šachl, Libor ; Klimeš, Luděk (advisor) ; Bulant, Petr (referee)
Title: Ray-based Born approximation Author: Libor Šachl Department: Department of Geophysics Supervisor: RNDr. Luděk Klimeš, DrSc. Supervisor's e-mail address: klimes@seis.karlov.mff.cuni.cz Abstract: One of the aims of this thesis was coding of program grdborn.for for computing the 2D and 3D ray-based Born approximation of the first order in an inhomoge- nous isotropic medium without attenuation. The computation of 3D amplitudes using the 2D Born approximation is based on the correction term, which is de- rived. The program is further used in computing the Born approximation in various models. We test its performance in three simple models. We study the effect of the discretization, the spurious waves introduced by the finite size of the grid etc. In the next step, we focus on the computations in more compli- cated models. We compute the Born seismograms in 2D heterogenous models. We study the diffracted waves, the effects of caustics etc. Keywords: Born approximation, ray theory, velocity model, perturbation 1
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