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 19 of 19 for “"source inversion"”.
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Bayesian source inversion of microseismic events
Rapid stress release at the source of an earthquake produces seismic waves. Observations of the particle motions from such waves are used in source inversion to characterise the dynamic behaviour of the source and to help in understanding the driving processes. Earthquakes either occur naturally, …
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Real-time GNSS for fast seismic source inversion and tsunami early warning
… application of real-time GNSS to fast seismic source inversion and tsunami early warning. Firstly, we present a new approach to get precise co-seismic displacements using cost effective single-frequency receivers. As is well known, with regard to high precision positioning, the main obstacle …
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Exploiting Artificial Intelligence in Volcanic Monitoring for Distributed Acoustic Sensing Analysis and GNSS-Based Source Inversion [L’Intelligenza Artificiale per il monitoraggio vulcanico: analisi di segnali DAS e modellazione della sorgente tramite inversione di dati GNSS]
… di ottimizzazione per risolvere il problema dell'inversione. Impieghiamo il deep learning per invertire i dati GNSS al fine di modellare sorgenti in sovrapressione. Presentiamo VulcanIA, un framework di deep learning per stimare le probabilità di sovrapressione nel dominio tridimensionale a …
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Modeling and inversion of self-potential data
… relevant to the acquisition, modeling, and inversion of self-potential data. The primary goal is to facilitate the interpretation of self-potentials in terms of the underlying mechanisms that generate the measured signal. The central component of this work describes a methodology for …
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Inversion of seismic source parameters for weak mining-induced and natural earthquakes
… of this thesis is to develop an automated inversion scheme to derive point and finite source parameters for weak earthquakes, here intended with the unusual meaning of earthquakes with magnitudes at the limit or below the bottom magnitude threshold of standard source inversion routines. The …
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Global investigation of large earthquakes using long-period seismic data
Robust earthquake source models provide key information for a wide range of applications in Earth Sciences, such as in global tectonics, natural hazards and tomographic studies. In this thesis, we study large magnitude earthquakes using the Earth’s normal modes, which are standing waves resulting …
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Carbon Data Assimilation Using an Ensemble Kalman Filter
… step to build an ensemble data assimilation and source inversion system for atmospheric carbon, I implemented column-integrated carbon monoxide (CO) mixing ratio assimilation capability in an ensemble Kalman filter (EnKF) data assimilation system with the Weather Research and Forecasting model …
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Global investigation of large earthquakes using InSAR and long-period seismic data
… comprehensive global archive of InSAR-determined source models (ICMT database) compiled from the literature, which I use to independently assess source parameters reported in global and regional seismic catalogues. In general there is good agreement between InSAR and seismic source models, but …
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Characterizing methane emissions on oil and gas sites
… scale. This thesis introduces a number of inversion techniques that use methane concentration measurements from point sensor networks to infer emission characteristics on oil and gas sites. We first introduce an inversion method for inferring single-source emission characteristics, such as …
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The state of the art time-domain wavefield imaging using a discontinuous Galerkin forward-backward time-stepping method
… of TD and single-frequency FD MWI, DGM-Contrast Source Inversion (CSI) and DGM-Gauss Newton Inversion (GNI) schemes are used as the FD counterparts, all implemented in Matlab. For experimental data, the DGM-FBTS algorithm shows a robust noise performance, generating higher-resolution results than …
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Improving Deep Exploration with Cost-Effective Geophysical Methods
… by combining geophysical, borehole, and open-source spatial data, a 3D model was synthesized for a volcanogenic massive sulphide (VMS) deposit located in Nash Creek, NB. Evaluating this model showed a need for structural controls to better understand the genesis of the deposit. A lesser-known …
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Numerical approaches for sequential Bayesian optimal experimental design
… Well-chosen experiments can save substantial resources, and hence optimal experimental design (OED) seeks to quantify and maximize the value of experimental data. Common current practice for designing a sequence of experiments uses suboptimal approaches: batch (open-loop) design that chooses all …
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Investigation of Source Extension Methods, the Discrepancy Algorithm, and Noise Estimation to Overcome Cycle Skipping in Full Waveform Inversion
Full waveform inversion (FWI) is a geophysical technique used to create highly detailed mod- els of the Earth’s subsurface which can be used to explore for hydrocarbons and to predict natural hazards such as earthquakes. Seismic waves are generated from controlled sources such as vibroseis trucks …
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A quasi-dynamic and self-consistent rupture model to simulate earthquake ruptures
… defined by a previously performed moment tensor inversion. The simultanously inverted scalar seismic moment allows an estimation of the extension of the rupture. The modeled rupture plane is discretized by a set of rectangular boundary elements. For each boundary element an applied traction …
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Goal-oriented inference : theoretical foundations and application to carbon capture and storage
… subspace reveals inefficiency in experiment and sources of uncertainty in predictions, which can also be utilized in experimental design. Linear goal-oriented inference is demonstrated on a model problem in contaminant source inversion and prediction. In the nonlinear setting, we focus on the …
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All-optical photoacoustic and laser-ultrasonic imaging in heterogeneous tissue
… as a pressure wave. The wavelength of the source laser can be tuned such that absorption occurs either primarily at the tissue surface, generating a laser-ultrasound (LUS) wave, or deep inside to create photoacoustic (PA) waves due to absorption by embedded tissue chromophores. LUS waves …
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Microwave Imaging and Sensing Algorithms for Brain Stroke Diagnosis
L'abstract è presente nell'allegato / the abstract is in the attachment
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Microwave imaging for breast cancer detection. Safety assessment, quantitative imaging, and breast density classification.
L'abstract è presente nell'allegato / the abstract is in the attachment