Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 29 for “"reverse-time"”.
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I. THE FIRST MULTI-DIMENSIONAL INVERSE-SCATTERING-SERIES INTERNAL-MULTIPLE-ELIMINATION METHOD: A NEW TOOLBOX OPTION FOR REMOVING INTERNAL MULTIPLES THAT INTERFERE WITH A PRIMARY, WITHOUT DAMAGING THE PRIMARY, AND WITHOUT ANY KNOWLEDGE OF SUBSURFACE PROPERTIES II. TESTS AND ANALYSIS FOR RESOLUTION COMPARISONS BETWEEN REVERSE TIME MIGRATION (RTM) AND THE FIRST MIGRATION METHOD THAT IS EQUALLY EFFECTIVE AT ALL FREQUENCIES AT THE TARGET
The general goal of seismic exploration is to develop new capabilities in the seismic toolbox to increase our ability to locate hydrocarbons. There is a seismic processing chain of linked tasks that processes the data recorded by the receivers and produces subsurface images to serve that goal and …
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Wave propagation in complex media, scattering theory, and application to seismic imaging
… an imaging algorithm referred to as nonlinear reverse-time migration. This migration exploits multiply scattered waves, including internal multiples, and is of particular interest for advanced interpretation in complex subsurface environment. In the exploration industry, the development of new …
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Brachiating power line inspection robot: controller design and implementation
… and uncertainty in joint friction over time. The resulting robust control system was able to compensate for uncertain system parameters and reject disturbances in simulation. An online trajectory generator (OTG), inspired by Raibert-style reverse-time symmetry[10], fed into the control …
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Automating Pre-Stack Migration Enhancement and Image Quality Analysis
… this principle, I process one reflection at a time in each iteration by isolating it into a local window and then flattening it. Also, I apply internal processing steps in order to enhance the signal. The algorithm of segregating a reflection is called the connected-component labeling (CCL) …
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Tensorial elastodynamics and acoustodynamics for generalized seismic migration and inversion applications
… effort for such applications as elastic reverse-time migration (E-RTM) and full waveform inversion (E-FWI). However, real-life scenarios often require computing solutions for computational domains characterized by non-Cartesian geometry (e.g., free-surface topography). The majority of the …
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Tensorial elastodynamics and acoustodynamics for generalized seismic migration and inversion applications
… effort for such applications as elastic reverse-time migration (E-RTM) and full waveform inversion (E-FWI). However, real-life scenarios often require computing solutions for computational domains characterized by non-Cartesian geometry (e.g., free-surface topography). The majority of the …
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The electrolytic production of lead chromate using periodically reversed direct current and superimposed alternating current on direct current
… to study the effect of varying the direct to reverse time ratio of periodically reversed direct current from 1.0 to 20.0 on the electrolytic production of lead chromate at an average anode current density of 0.0059 amperes per square centimeter, and to study the effect of 60 and 502.3 ± 7.7 …
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Computational Solutions of the Forward and Adjoint Euler Equations with Application to Duct Aeroacoustics
… waves at all frequencies can be obtained by Time Domain Wave Packet (TDWP) method in a single time domain computation. The TDWP method is also particularly useful for computations in the ducted or waveguide environments where incident wave modes can be imposed cleanly without a potentially …
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The electrolytic production of peroxydisulfuric acid using periodically reversed direct current and alternating current superimposed on direct current
… to study the effect of varying the direct to reverse time ratio of periodically-reversed, direct current from 1.0 to 20.0 at an anode current density of 4.5 amperes per square centimeter, and to study the effect of alternating current of 60, 240, and 500 cycles per second, 0.2 to 4.5 amperes …
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Seismic Imaging and Velocity Model Building in the Thrace Region, Northwestern Turkey: A Case Study
… fore-arc basin during medial Eocene to Oligocene time. The thickness of the basin-fill deposits is estimated to be up to 9 km deep. This work applied conventional seismic data processing and imaging techniques. Kirchhoff pre-stack time and depth migration are used. Tomography approach was used to …
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Validación del modelo Retain para el análisis de registros médicos electrónicos en el cuidado de la salud
… en los últimos años es el modelo Retain (REverse Time AttentIoN). Retain introduce un mecanismo de atención a las RNN, permitiendo al modelo enfocarse en las distintas visitas y características relevantes dentro de los EHR. En este artículo, nuestro objetivo es implementar un modelo para …
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Multi-scale deformable layer reflection tomography and application to estimate base-salt geometry
… a migrated image. This process can be extremely time-consuming and resource intensive for a complex salt geometry and can be even more tedious in the presence of salt overhangs. The interpretation of base-salt geometry is often the most challenging part of the workflow, because salt base is …
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A study of prompt fast ion losses from neutral beam injection in the DIII-D tokamak
… based fast ion loss detectors (FILD) and a reverse orbit calculation code. Prompt losses, also called first orbit losses, result from injected neutrals that are ionized on orbits that terminate to the outer wall before making a complete neoclassical, poloidal revolution. A strike map code …
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Modelling, Migration, and Inversion for Angle Domain Common Image Gathers
… based on reflection angle extraction methods in Reverse Time Migration (RTM) fullfilling the requirement of the true amplitude migration. The inversion of ADCIGs predicts both velocity and angle-dependent reflectivity based on Full Waveform Inversion (FWI). Advances in high-performance computing …
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Continental Arc Processes in British Columbia and Earthquake Processes in Virginia: Insights from Seismic Imaging
Travel times from a refraction and wide-angle reflection seismic survey across the Coast Plutonic Complex and Stikine terrane of British Columbia were inverted to derive two dimensional P and S-wave seismic velocity models of the crust and uppermost mantle. A felsic upper crust and a felsic to …
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Analytical and Numerical Optimal Motion Planning for an Underwater Glider
… and trajectory. The vehicles spend most of their time in long, steady glides, so even minor improvements in glide range can be magnified over multiple dives. This dissertation presents a rigid-body dynamic system for a generic vehicle operating in a moving fluid (ocean current or wind). The model …
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Seismic imaging using internal multiples and overturned waves
… salt bodies. Existing migration methods, such as Reverse Time Migration, are usually designed to image solely with primaries, and so do not make full use of energy propagating along other wave paths. In this thesis I describe several modifications to existing seismic migration algorithms to enable …
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Spectrum sharing for multi-user massive MIMO networks
… techniques at the SN for both conventional time-division duplexing (C-TDD) and reverse time-division duplexing (R-TDD) protocols. In the C-TDD approach, both the PN and SN operate concurrently in either the uplink (UL) or downlink (DL) modes. In the R-TDD protocol, the PN and SN do not …
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Direct Waveform Inversion Using Explicit Time-Space Causality Principle
… in the DWI is the explicit use of the wavefield time-space causality property in the inversion, which allows us to convert the global non-linear optimization problem in the FWI, without losing information, into local linear inversions that can be readily solved. The DWI is a recursive scheme …
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Inverse scattering : theory and application to the imaging of the Earth's seismic discontinuities
… a new method, which we call passive source reverse time migration (RTM), for subsurface imaging with teleseismic array data. Multi-component array data are first propagated backward by solving the elastic wave equation. After polarization separation, a modified cross-correlation imaging …
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