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Articles 1 - 8 of 8
Full-Text Articles in Physical Sciences and Mathematics
Encoding A 1-D Heisenberg Spin 1/2 Chain In A Simulated Annealing Algorithm For Machine Learning, Daniel Pompa
Encoding A 1-D Heisenberg Spin 1/2 Chain In A Simulated Annealing Algorithm For Machine Learning, Daniel Pompa
Honors Theses
The application areas of machine learning techniques are becoming broader and increasingly ubiquitous in the natural sciences and engineering. One such field of interest within the physics community is the training and implementation of neural networks to aid in quantum many-body computations. Conversely, research exploring the possible computational benefits of using quantum many-body dynamics in the area of artificial intelligence and machine learning has also recently started to gain traction. The marriage of these fields comes naturally with the complementary nature of their mathematical frameworks. The objective of this study was to explore the possibility of encoding a quantum spin …
Wind-Induced Ground Motion: Dynamic Model And Non-Uniform Structure For Ground, Mohammad Mohammadi, Craig J. Hickey, Richard Raspet, Vahid Naderyan
Wind-Induced Ground Motion: Dynamic Model And Non-Uniform Structure For Ground, Mohammad Mohammadi, Craig J. Hickey, Richard Raspet, Vahid Naderyan
Faculty and Student Publications
Wind-induced ground vibrations are a source of noise in seismic surveys. In a previous study, a wind-ground coupling theory was developed to predict the power spectral density (PSD) of ground motions caused by wind perturbations on the ground surface. The prediction was developed using a superposition of the point source response of an elastic isotropic homogeneous medium deforming quasi-statically with the statistical description of the wind-induced pressure fluctuations on the ground. Model predictions and field measurements were in agreement for the normal component of the displacement but under predicted the horizontal component. In this paper, two generalizations are investigated to …
Geographic Variations Of Sound Channel Axis In The Global Ocean, Mukunda Kumar Acharya
Geographic Variations Of Sound Channel Axis In The Global Ocean, Mukunda Kumar Acharya
Electronic Theses and Dissertations
Sound signals are used for imaging and communication in the ocean. Underwater sound speed has a minimum at a certain depth that forms a sound channel for long-range underwater sound propagation. The geographic variation of sound channel is crucial in uses of underwater sound in various environments including ocean acoustic tomography and monitoring of global warming. In this work, sound speed and depth of the channel axis in the global ocean are characterized for their variation with the latitude, longitude, and depth.
Manifoldlike Causal Sets, Miremad Aghili
Manifoldlike Causal Sets, Miremad Aghili
Electronic Theses and Dissertations
The content of this dissertation is written in a way to answer the important question of manifold likeness of causal sets. This problem has importance in the sense that in the continuum limit and in the case one finds a formalism for the sum over histories, the result requires to be embeddable in a manifold to be able to reproduce General Relativity. In what follows I will use the distribution of path length in a causal set to assign a measure for manifold likeness of causal sets to eliminate the dominance of nonmanifold like causal sets. The distribution of interval …
Acoustic Radiation Force On A Fluid To Fluid Boundary By Phase Plate Focused Ultrasound, Robert Lee Lirette
Acoustic Radiation Force On A Fluid To Fluid Boundary By Phase Plate Focused Ultrasound, Robert Lee Lirette
Electronic Theses and Dissertations
In this study, the physics and applications of the ultrasonic radiation force at the interface between two immiscible fluids were investigated. These studies were performed using low-profile discrete-stepped lenses to the modify the phase of the incident radiation generating multiple field morphologies. In its first application to acoustics, a fraxicon lens was developed to approximate the field generated by an axicon. This type of lens creates a minimally diffractive Bessel beam and long depth of focus that is useful in ultrasonic imaging, therapy, and non-destructive evaluation techniques. Fields modified by fraxicon, Fresnel, and axicon lenses were characterized experimentally by scanning …
Gravitational Radiation From Superradiant Instabilities Of Rotating Black Holes, Shrobana Ghosh
Gravitational Radiation From Superradiant Instabilities Of Rotating Black Holes, Shrobana Ghosh
Electronic Theses and Dissertations
We use the Teukolsky formalism to calculate the gravitational radiation from a non-axi\-symmetric cloud formed due to superradiant amplification of a spin-0 bosonic field. We focus on the prospects of the future space-based gravitational wave detector, Laser Interferometer Space Antenna (LISA), and the current version of ground-based detector, Advanced Laser Interferometer Gravitational-Wave Observatory (AdLIGO), to detect or constrain scalars with mass in the range $m_s\in [10^{-19},10^{-15}]$ eV and $m_s\in[10^{-14},10^{-11}]$ eV, respectively. Using astrophysical models of black hole populations calibrated to observations we find that, in optimistic scenarios, AdLIGO could detect up to $10^4$ resolvable events in a four-year search if …
Investigation Of Narrow Bipolar Events In Mississippi Thunderstorms, Sampath Asiri Bandara
Investigation Of Narrow Bipolar Events In Mississippi Thunderstorms, Sampath Asiri Bandara
Electronic Theses and Dissertations
In the first part of the study FA and Log-RF data were used to examine low-altitude (<8.0 km) negative NBEs (NNBEs) to see how many -CG flashes were initiated by NNBEs. Out of 686 -CG flashes only 33 (5%) flashes were initiated by an NNBE. These NNBEs occurred at an average altitude of 6.2 km had average amplitude (range-normalized amplitude to 100 km) of 0.4 V/m and had average VHF (Log-RF) power of 130 W. Since the low-altitude NNBEs were substantially weaker than positive NBEs that initiate intracloud (IC) flashes it is hypothesized that -CG flashes are easier to initiate than IC flashes. The second part of the study investigated the properties of 201 positive NBEs (+NBEs). The +NBEs were classified in two ways: into Types A-D [Karunarathne et al. 2015] and into three different groups: Isolated Not-isolated and IC flash-initiator or INBE [Wu et al. 2014]. The average VHF (Log-RF) power of NBEs within the A-D categories were 1.9 4 9.8 and 13.2 kW respectively while the powers for the Isolated Not-isolated and INBE categories were 10.1 4 and 10.1 kW respectively. The third study considered 34 NBEs that occurred close in space and time to each other: 13 pairs of NBEs one group of three +NBEs and one group of five +NBEs. The NBEs were overlaid on radar data of the parent thunderstorms. The data indicate that the individual NBEs in each group initiated in separate intense electric field regions of small extent rather than in a single large-scale electric field region. This dissertation investigates Narrow Bipolar Events (NBEs) which are a type of short-duration (10- 30 µs) lightning discharge. The study primarily used data from NBEs collected in 2016 at seven sensor sites within 50 km of Oxford Mississippi USA. Each sensor site had three electromagnetic antennas called Fast Antenna (FA) dE⁄dt and Log-RF with bandwidths of 0-2.5 MHz 0-1.0 MHz and 186-192 MHz respectively. NBEs are often isolated from other lightning events in thunderclouds but they sometimes initiate negative cloud-to-ground (-CG) and intracloud (IC) lightning flashes or they can occur during these flashes.
Measurements Of The Primary Bjerknes Force In A Cavitating Ultrasonic Field, Mason Smith
Measurements Of The Primary Bjerknes Force In A Cavitating Ultrasonic Field, Mason Smith
Honors Theses
Cavitation is the result when there are rapid changes in pressure in a liquid. These vapor-filled cavities can occur when ultrasound propagates through water at sufficient power. The volumes of these cavities can pulsate and can even couple with the radiation pressure from the ultrasound. The result is a translational force on the bubbles. This translational force on the bubble is called the primary Bjerknes force. The secondary Bjerknes force is the result of two pulsating cavities, but this force is ignored since the buoyant force and the primary Bjerknes force are the dominant forces. Immediately before a bubble begins …