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 23 for “"tomographic inversion"”.
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Tomographic inversion of Pn travel times in western China
… crustal thickness for western China using a Pn tomographic inversion based on a large collection of Pn travel time data from various sources. Our tomography image reveals four significant features corresponding to the surface geology: (1) Four major basins bordering the Tibetan Plateau (TP) …
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Analysis of acoustic propagation in the region of the New England continental shelfbreak
… of acoustic propagation in the region, and tomographic inversion of the acoustic data. In addition, this thesis develops a new method for predicting acoustic coherence in such regions. Receptions from two 400 Hz tomography sources, transmitting from the continental slope onto the shelf, are …
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Analysis of acoustic propagation in the region of the New England continental shelfbreak
… of acoustic propagation in the region, and tomographic inversion of the acoustic data. In addition, this thesis develops a new method for predicting acoustic coherence in such regions. Receptions from two 400 Hz tomography sources, transmitting from the continental slope onto the shelf, are …
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A tomographic ocean sound speed profile from a long veritcal acoustic array
… of repetitions of the signal are performed. The tomographic inversion is initialized from a range averaged climatological profile. Multipaths are identified from ray theory. The identified arrivals are inverted for a range-independent sound speed profile change estimate. Estimates of source and …
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Multi-dimensional Flow and Combustion Diagnostics
… tomography (HT) technique, and a 4D tomographic chemiluminescence (TC) technique. The first TPLIF technique is targeted at measuring temporally-resolved 2D distribution of fluorescent radicals, the second HT technique is targeted at measuring temperature and chemical species …
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Geophone Array Optimization for Monitoring Geologic Carbon Sequestration using Double-Difference Tomography
… performed to determine the most cost-effective tomographic monitoring system for a geologic carbon sequestration injection site. Artificial velocity models were created that accounted for the expected velocity decrease due to the existence of a CO₂ plume after underground injection into a …
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Local Earthquake Tomography at Mt. Pinatubo, Philippines
… model for Mt. Pinatubo volcano was developed by tomographic inversion of P-wave arrivals from 3,007 earthquakes recorded during a four month period from May to August, 1991. The arrivals were recorded by a network of seismic stations, consisting of seven pre-eruption stations and seven …
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The tectonics and three-dimensional structure of spreading centers : microearthquake studies and tomographic inversions
… is investigated with microearthquake studies or tomographic inversion of travel times. Results of these studies are used to constrain the spatial variability of physical properties and processes beneath the axis of spreading and, together with other observations, the temporal characteristics of …
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Multi-scale deformable layer reflection tomography and application to estimate base-salt geometry
… migration. To mitigate the non-uniqueness of the tomographic inversion, we have further developed a multi-scale inversion. Compared with the single-scale RLT, the multi-scale RLT delivers superior results in delineating the base-salt geometry, as demonstrated by the synthetic examples. In …
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Applications of Double-Difference Tomography for a Deep Hard Rock Mine
… set used for the double-difference tomography inversion was from Creighton Mine in Sudbury, Ontario, Canada, and consisted of two months of data averaging 150 microseismic events per day. Three separate studies were conducted to evaluate the applications of double-difference tomography on a …
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Seismological structure of the Carpathian-Pannonian region of central Europe
… a further 44 permanent broadband seismometers, tomographic inversion of P and S-wave relative arrival-time residuals from teleseismic earthquakes, reveal the velocity structure of the mantle to a depth of 850 km throughout the Carpathian-Pannonian region. The tomographic models reduce the P-wave …
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2-D radio imaging of equatorial ionospheric plasma depletions with the C/NOFS satellite: algorithms and results
… and ground instruments, together with tomographic inversion techniques, to obtain multi-dimensional images of the ionospheric electron density. However, the inverse problem has some noted challenges due to inherent constraints on the acquisition geometry. One such system is based on …
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Imaging the Soultz Enhanced Geothermal Reservoir using double-difference tomography and microseismic data
… times and then performed a double-difference tomographic inversion to jointly invert for velocity structure and event locations. It is shown through a detailed analysis of model and data residuals vs smoothing weight, ray path derivative weighted sums, and a synthetic checkerboard test that …
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Tomographic Imaging Associated with a Mw 2.6 Fault-Slip Event in a Deep Nickel Mine
… (Westman, 2003). This paper utilizes a tomographic inversion scheme using the Fast Marching Method for raypath tracing and the Simultaneous Iterative Reconstruction Technique to solve the p-wave velocity model of an underground mine and surrounding rock mass. The inversion scheme …
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Acoustic full-waveform to elastic pre-stack seismic inversion of the Yakutat Terrane, Gulf of Alaska
… acoustic and isotropic time-domain full waveform inversion (FWI) of marine seismic reflection and refraction data from the STEEP project (ST. Elias Erosion/tectonics Project). FWI is a non-linear data-fitting algorithm that aims to recover subsurface parameters from the recorded seismic wavefield. …
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Resolving Small Objects Using Seismic Traveltime Tomography
… however, that the relevant Fresnel limit for tomographic resolution is the maximum, not the dominant frequency in the data. For physically realizable causal wavelets, the maximum frequency is infinite. In practice, noise lowers the effective possible maximum frequency. To demonstrate these …
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The tectonics and three-dimensional structure of spreading centers--microearthquake studies and tomographic inversions
… is investigated with microearthquake studies or tomographic inversion of travel times. Results of these studies are used to constrain the spatial variability of physical properties and processes beneath the axis of spreading and, together with other observations, the temporal characteristics of …
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Quantification of the spatial structure and temporal variability of Earth's exosphere using optical tomography
… quantification of exospheric H density through tomographic inversion of scattered H Ly-a emission. This approach avoids the historical dependence on ad hoc parametric formulations of the H density distribution and enables more reliable characterization of global outer exospheric. The …
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Three-dimensional water vapor retrieval using a network of scanning compact microwave radiometers
… km horizontal displacement from its launch site. Tomographic inversion applied to ground-based measurements of GPS wet delay is expected to yield data with 0.5-1 km vertical resolution at 30-minute intervals. COSMIC and CHAMP satellites in low earth orbit (LEO) provide measurements with 0.1-0.5 km …
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