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 52 for “"Green’s function"”.
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Stochastic green’s function method for the statistical analysis of wave chaotic systems
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-05-01
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Mathematical modelling of noise generation in turbofan aeroengines using Green’s functions
… in two distinct ways, firstly we calculate the Green’s function for pressure in a turbofan duct with swirling mean flow and secondly we investigate the effect of turbulence hitting an isolated aerofoil. The Green’s function allows engineers to calculate the noise from rotor-stator interaction in …
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Dosimetry of High-Energy Heavy-Ion Beams Using Energy-Dependent Green's Functions
… tissue is developed. The energy-dependent Green’s functions and particle fluxes are obtained for two boundary distributions - the monoenergetic and the Gaussian. Approximate energy-dependent Green’s functions for the collision terms are obtained for computational simplicity. As an …
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Dilute nitride semiconductors : band structure, scattering and high field transport
… of GaNxAs1−x, where this gap is filled in the Green’s function model. Therefore we develop a self-consistent Green’s function (SCGF) approach, which provides excellent agreement with supercell calculations and reveals a gap in the DOS, in contrast with the results of previous …
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Developments in the Theory of X-ray Absorption and Compton Scattering.
… properties are described by single particle Green’s function theory. In strongly correlated systems, such as transition metal oxides, it is necessary to go beyond single particle treatment in order to reasonably describe peaks in XAS spectra. In this thesis I present a simplified, …
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A reactor physics framework to detect anomalies in HTGR core
… as well as the zero-power reactor transfer functions. The results show that, generally, the neutron noise in HTGRs exhibits a similar behavior to that in LWRs. However, there are a few aspects that distinguish HTGRs. From the zero-power reactor transfer function, HTGRs have a lower plateau, …
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Simulation of graphene electronic devices
… from them were obtained using a nonequilibrium Green’s function formulation. The effects of defects and strain on these systems were also studied using this technique. Advancements were made when the self-energies used within the nonequilibrium Green’s function were obtained from an iterative …
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Topics in diffuse field ultrasonics
… The first concerns the identification of the Green’s function with the cross-correlation produced from a diffuse wave field. This has been termed Green’s Function Retrieval. Of particular concern is the accurate retrieval of amplitude when the wave field fails to be fully diffuse. The second …
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A first principles study of defects in titanium: interaction of twin boundaries with dislocations and oxygen interstitials
… with a new method to compute the lattice Green’s function for crystals containing a planar interface, we present a general method to study line defects interacting with interfaces with a tractable number of atoms. This method is general in the sense that it can consider long range atomic …
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Phonon and electron transport through interfaces and disordered structures
… using structural randomness via mode-resolved Green’s function calculations and pump-probe optical characterizations. Interface roughness is a common type of randomness in heterostructures, which strongly affects electron and phonon transport across interfaces. We find that atomically rough …
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Electron-phonon interactions in double layer graphene superfluids
… graphene monolayers. We use the non- equilibrium Green’s function (NEGF) formalism to examine the effect that carrier-phonon scattering has on transport in such a device. The simulations show that the effect of carrier-phonon scattering has a strong dependence on the device coherence length, the …
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Theory of molecular scale thermoelectricity
In this thesis we use a combination of density functional theory and equilibrium Green’s function to study thermoelectricity in molecular scale. We have aimed to improve the efficiency of single molecules in converting heat to electricity by carefully designing them. We introduced a novel strategy …
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Studies of Light Scalar Particles and Dressed Gauge Propagators in QCD
… gluons, ghosts and quarks which describe how a Green’s function behaves non-perturbatively. We primarily investigate the coupled gluon and ghost system without quarks. We find that non–trivial vertices are required to obtain self–consistent solutions in the simplest truncation and that a …
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Quantum transport in Josephson junctions
… we utilise the techniques of non-equilibrium Green’s functions; capable of probing the interplay between coherent quantum effects over macroscopic distances. We begin by broadly discussing the quantum mechanical techniques required in this work, before deriving the relevant equations to be …
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Angle-Resolved Photoelectron Spectroscopy Studies of the Many-Body Effects in the Electronic Structure of High-Tc Cuprates
… excitation spectrum of the material as a function of both momentum and energy with very high resolution. Other experimental techniques, such as inelastic neutron scattering (INS), Raman spectroscopy, or the newly estab-lished Fourier-transform scanning tunneling spectroscopy (FT-STS) probe …
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Phonon-mediated Casimir effect
… field perpendicular to the easy axis, the Green’s function demonstrates the branch cut behavior. It is contrasted to the systems of an itinerant quasiparticle in the antiferromagnetic background where the quasiparticle retains the finite quasiparticle weight. The considered magnon …
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The radiation physics, mitigation approaches and design guidelines of high-speed connectors and cables analyzed with numerical modeling, analytical formulation and measurements
… radiation mechanisms are analyzed through Green’s function method, steepest descent method, and EMC Studio method of moment (MoM). Design guidelines of high-speed connectors for EMI mitigation are proposed based on the analysis of radiation physics.</p><p>In the third paper, the 2D finite …
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AI-Driven Discovery and Multiscale Computational Frameworks for Carbon-Based Materials
… generative system. Here, an oracle-based scoring function provides feedback from machine learning predicted adsorption metric, dynamically steering the generative model toward desirable regions of the property space. This self-optimizing loop improves both discovery efficiency, physical fidelity, …
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Computational modeling of defects in nanoscale device materials
… performed in this thesis, consisting of density functional theory (DFT) supplemented with many body perturbation theory (MBPT) methods, of native defects in bulk and slab models of In0.53Ga0.47As. The latter consist of (100) - oriented surfaces passivated with A12O3. Our results indicate that the …
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Quantum Theory of Electron Transport Through Photo-Synthetic Porphyrins
… be included in the theoretical approach; Density Functional Theory, which is implemented in the SIESTA code, and the Green’s function formalism of electron transport (Chapter 2), which is implemented in the GOLLUM code. Both techniques are used extensively to study a family of metallo-porphyrin …
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