Physical Sciences and Mathematics Commons^™

On Hall Magnetohydrodynamics: X-Type Neutral Point And Parker Problem, Kyle Reger

Electronic Theses and Dissertations

The framework for the Hall magnetohydrodynamic (MHD) model for plasma physics is built up from kinetic theory and used to analytically solve problems of interest in the field. The Hall MHD model describes fast magnetic reconnection processes in space and laboratory plasmas. Specifically, the magnetic reconnection process at an X-type neutral point, where current sheets form and store enormous amounts of magnetic energy which is later released as magnetic storms when the sheets break up, is investigated. The phenomena of magnetic flux pile-up driving the merging of antiparallel magnetic fields at an ion stagnation-point flow in a thin current sheet, …

Role Of Internal Degrees Of Freedom In The Quantum Tunneling Of The Magnetization In Single-Molecule Magnets, Hajrah Quddusi

Electronic Theses and Dissertations

The prominent features of single molecule magnets (SMMs), such as the quantum tunneling of the magnetization (QTM), are conventionally understood through the giant spin approximation (GSA) which considers the molecule as a single rigid spin. This model often requires the inclusion of high order anisotropy terms in the Hamiltonian, a manifestation of admixing of low lying excited states that can be more naturally understood by employing a multi-spin (MS) description i.e. considering the individual spins and the interactions between ions within the molecule. However, solving the MS Hamiltonian for high nuclearity molecules is not feasible due to the enormous dimensions …

Applications Of Compressive Sensing To Surveillance Problems, Christopher Huff

Electronic Theses and Dissertations

In many surveillance scenarios, one concern that arises is how to construct an imager that is capable of capturing the scene with high fidelity. This could be problematic for two reasons: first, the optics and electronics in the camera may have difficulty in dealing with so much information; secondly, bandwidth constraints, may pose difficulty in transmitting information from the imager to the user efficiently for reconstruction or realization. In this thesis, we will discuss a mathematical framework that is capable of skirting the two aforementioned issues. This framework is rooted in a technique commonly referred to as compressive sensing. We …

A Study Of The Degradative Capabilities Of The Bimetallic System: Mg(Pd/C) As Applied In The Destruction Of Decafluoropentane, An Environmental Contaminant, Douglas Tomlin

Electronic Theses and Dissertations

Pollution from hydrofluorocarbons (HFC) poses a serious challenge to the environmental community. Released from industrial operations, they have contaminated both the atmosphere and groundwater and are considered persistent in both media.1 For over the past 20 years, the practice of synthesizing hydrofluorocarbons as alternatives to chlorofluorocarbons (CFC) has been conducted in an effort to reverse the effects of stratospheric ozone layer depletion. 2,3 However, in doing so these new fluorinated compounds exhibited an unexpected property as a potent global warming greenhouse gas (GHG) with radiative forcing potentials in the range of 100 to 10,000 equivalents greater than carbon dioxide.4 Conversely, …

Efficient And Scalable Evaluation Of Continuous, Spatio-Temporal Queries In Mobile Computing Environments, Jonathan M. Cazalas

Electronic Theses and Dissertations

A variety of research exists for the processing of continuous queries in large, mobile environments. Each method tries, in its own way, to address the computational bottleneck of constantly processing so many queries. For this research, we present a two-pronged approach at addressing this problem. Firstly, we introduce an efficient and scalable system for monitoring traditional, continuous queries by leveraging the parallel processing capability of the Graphics Processing Unit. We examine a naive CPU-based solution for continuous range-monitoring queries, and we then extend this system using the GPU. Additionally, with mobile communication devices becoming commodity, location-based services will become ubiquitous. …

Cayley-Dickson Loops, Jenya Kirshtein

Electronic Theses and Dissertations

In this dissertation we study the Cayley-Dickson loops, multiplicative structures arising from the standard Cayley-Dickson doubling process. More precisely, the Cayley-Dickson loop Q_n is the multiplicative closure of basic elements of the algebra constructed by n applications of the doubling process (the first few examples of such algebras are real numbers, complex numbers, quaternions, octonions, sedenions). Starting at the octonions, Cayley-Dickson algebras and loops become nonassociative, which presents a significant challenge in their study.

We begin by describing basic properties of the Cayley–Dickson loops Q_n. We establish or recall elementary facts about Q_n, e.g., inverses, …

Tensor Products Of Vector Seminormed Spaces, John William Dever

Electronic Theses and Dissertations

A vector seminormed space is a triple consisting of a vector space, a Dedekind complete Riesz space, and a vector valued seminorm, called a vector seminorm, defined on the vector space and taking values in the Riesz space. The collection of vector seminormed spaces with suitably defined morphisms is shown to be a category containing finite products. A theory of vector seminorms on the tensor products of vector seminormed spaces is developed in analogy with the theory of tensor products of Banach spaces. Accordingly, a reasonable cross vector seminorm, or simply tensor seminorm, is defined such that a vector seminorm …

An Ssvep Brain-Computer Interface: A Machine Learning Approach, Fei Teng

Electronic Theses and Dissertations

A Brain-Computer Interface (BCI) provides a bidirectional communication path for a human to control an external device using brain signals. Among neurophysiological features in BCI systems, steady state visually evoked potentials (SSVEP), natural responses to visual stimulation at specific frequencies, has increasingly drawn attentions because of its high temporal resolution and minimal user training, which are two important parameters in evaluating a BCI system. The performance of a BCI can be improved by a properly selected neurophysiological signal, or by the introduction of machine learning techniques. With the help of machine learning methods, a BCI system can adapt to the …

Contributions To Robust Methods: Modified Rank Covariance Matrix And Spatial-Em Algorithm, Kai Yu

Electronic Theses and Dissertations

Classical multivariate statistical inference methods including multivariate analysis of variance, principal component analysis, factor analysis, canonical correlation analysis are based on sample covariance matrix. Those moment-based techniques are optimal (most efficient) under the normality distributional assumption. They are, however, extremely sensitive to outlying observations, susceptible to small perturbation in data and poor in the efficiency for heavy-tailed distributions. A straightforward treatment is to replace the sample covariance matrix with a robust one. Visuri et al. (2000) proposed a technique for robust covariance matrix estimation based on different notions of multivariate sign and rank. Among them, the spatial rank based covariance …

Optimization And Development Of In Vitro Bioassays To Determine Structure-Activity Relationships For Cannabinoid Receptor 1 And Cannabinoid Receptor 2, Afeef Husni

Electronic Theses and Dissertations

Cannabis has been around for thousands of years and has been used recreationally, medicinally, and for fiber. Over 400 compounds have been isolated from Cannabis sativa with approximately 100 being cannabinoids. Of those 100 compounds, Δ9-THC has been determined as the primary constituent, which is also responsible for the psychoactivity associated with Cannabis. Along with Δ9-THC, cannabidiol has been studied in depth for its therapeutic effects. This has currently been the focus of many researchers since cannabidiol does not cause psychotropic effects.

Cannabinoid receptors belong to the large superfamily of G protein-coupled receptors (GPCRs). Approximately 30% of marketed drugs target …

The Legendre Transform Of The Holst Action, Caixia Gao

Electronic Theses and Dissertations

I start with a short introduction on 3+1 ADM form and the tetrad form of General Relativity, then I review the Legendre transform of the Einstein-Hilbert action and the Palatini action. The Holst action is a generalization of the Palatini action by including a topological term. I derive Ashtekar's connection form directly from this action by doing the Legendre transformation rather than by a canonical transformation in the usual phase space. This is done in both Remmanian signature with half-flat connection and Lorentz signature with general Barbero-Immirzi parameter.

Simulation And Phases Of Macroscopic Particles In Vortex Flow, Heath Eric Rice

Electronic Theses and Dissertations

Granular materials are an interesting class of media in that they exhibit many disparate characteristics depending on conditions. The same set of particles may behave like a solid, liquid, gas, something in-between, or something completely unique depending on the conditions. Practically speaking, granular materials are used in many aspects of manufacturing, therefore any new information gleaned about them may help refine these techniques. For example, learning of a possible instability may help avoid it in practical application, saving machinery, money, and even personnel. To that end, we intend to simulate a granular medium under tornado-like vortex airflow by varying particle …

Multi-Configurational Investigation Of Thermolytic Pathways Of Highly Strained Ring Systems, Jeffrey Dwayne Veals

Electronic Theses and Dissertations

The isomerization pathways of model high energy structures are of interest because of their relation to high energy density fuels. Electron resonance has been found to greatly affect the relative activation barriers for several isomerization pathways, and the major goal of this research is to accurately describe its role in determining the relative barriers for strain energy release pathways. This research is centered around the potential energy surfaces (PES's) for ? bond breaking and ? bond rotation in these highly strained structures. Of particular interest was how would resonance and or electronegativity affect the allowed/disallonature of the activation barriers in …

Horizons, Holography And Hydrodynamics, Arif Mohd

Electronic Theses and Dissertations

In this dissertation we study black-hole horizons in general relativity and in Gauss-Bonnet gravity. We generalize Wald's "black-hole entropy is the Noether charge" construction to the first-order formalism of these theories. Next we construct the "membrane paradigm" for black objects in Gauss-Bonnet gravity and demonstrate how the horizon can be vieas a membrane with fluidlike properties. Holography is invoked to relate the transport coefficients obtained for the horizons in the membrane paradigm with the transport coefficients which describe the hydrodynamic limit of the boundary gauge theory.

Nonlinear Dynamic Modeling, Simulation And Characterization Of The Mesoscale Neuron-Electrode Interface, Vaibhav Thakore

Electronic Theses and Dissertations

Extracellular neuroelectronic interfacing has important applications in the fields of neural prosthetics, biological computation and whole-cell biosensing for drug screening and toxin detection. While the field of neuroelectronic interfacing holds great promise, the recording of high-fidelity signals from extracellular devices has long suffered from the problem of low signal-to-noise ratios and changes in signal shapes due to the presence of highly dispersive dielectric medium in the neuron-microelectrode cleft. This has made it difficult to correlate the extracellularly recorded signals with the intracellular signals recorded using conventional patch-clamp electrophysiology. For bringing about an improvement in the signalto-noise ratio of the signals …

Properties Of Weighted Generalized Beta Distribution Of The Second Kind, Yuan Ye

Electronic Theses and Dissertations

Author's abstract: In this thesis, a new class of weighted generalized beta distribution of the second kind (WGB2) is presented. The construction makes use of the conservability approach' which includes the size or length-biased distribution as a special case. The class of WGB2 is used as descriptive models for the distribution of income. The results that are presented generalize the generalized beta distribution of second kind (GB2). The properties of these distributions including behavior of pdf, cdf, hazard functions, moments, mean, variance, coefficient of variation (CV), coefficient of skewness (CS), coefficient of kurtosis (CK) are obtained. The moments of other …

Use Of Georphysics To Map Subsurface Features At Levee Seepage Locaitons, Thomas Chapman Brackett

Electronic Theses and Dissertations

The Great Flood of 2011 caused moderate to severe seepage and piping along the Mississippi River levees in Northwest Mississippi. The aim of this thesis was to implement geophysical techniques at two seepage locations in order to give a better understanding of the causes of underseepage and information on how to mitigate the problem. Sites near Rena Lara in Coahoma County and near Francis in Bolivar County were chosen to conduct this survey. Electrical Resistivity Tomography (ERT) and Electromagnetic Induction (EM) surveys were conducted on and adjacent to levees to identify seepage pathways and any dominant geological features at the …

Description Of Coherent Structures In The Atmospheric Boundary Layer By Model Reduction Of The Surface Pressure, Gregory William Lyons

Electronic Theses and Dissertations

The flow of coherent turbulent structures into a wind turbine is associated with vibrational blade excitation. Successful forecasting of such turbulent events for control system input would increase the lifetime of turbine components. The coherence of these features suggests description by model reduction. To this end, an array of pressure transducers was deployed on the ground at Reese Technology Center in Lubbock, Texas, and the pressure fluctuations were recorded over nearly two diurnal cycles. A program for computation of the dynamic mode decomposition was developed with special consideration for the case of a non-stationary, nonlinear system. A simulated surface-pressure perturbation …

Synthesis And Characterization Of Nickel Complexes With Relevance To Nickel Acireductone Dioxygenase And Nickel Superoxide Dismutase, Margo Nicole Montgomery

Electronic Theses and Dissertations

This research presents an investigation of synthetic model complexes with relevance to the active site of Ni(II) acireductone dioxygenase (Ni-ARD) and Ni(II) superoxide dismutase (Ni-SOD). Acireductone dioxygenases (ARDs) are a unique set of enzymes found in the methionine salvage pathway that catalyze the oxidation reaction of acireductone (1, 2-dihydroxy-3-oxo-5-(methylthio)pent-1-ene). These enzymes share a compolypeptide sequence but bind different metal ions, Ni2+ or Fe2+, at the active site. The Ni-ARD enzyme is responsible for the off pathway shunt in the pathway. Using the tridentate nitrogen donor ligands hydrotris(3,5-dimethyl-1-pyrazolyl)borate (Tp*) and the newly developed tris(1, 2-dimethyl-4-imadozyl)carbinol, (4-TICMe, Me) several reactions involving the …

Comparison Of Apple's Ios 5 And Android For Mobile Applications Development: A Developer's Perspective, Estela Pochintesta

Electronic Theses and Dissertations

Body composition, or the proportion of fat, muscle, and bone of an individual's body, is an important indication of health status. Numerous techniques can be used to assess body composition, producing varied results and measurements. For individuals with insufficient or excessive amounts of body fat, accurate assessment of body composition is crucial. Two commonly used techniques for measuring body composition are air displacement plethysmography (adp) and dual-energy x-ray absorptiometry (dxa). Past research has been conducted, comparing adp and dxa, but the results are inconsistent. The majority of past studies found that, when compared to dxa, adp underestimated body fat percentage, …

Non-Reciprocal Wave Transmission In Integrated Waveguide Array Isolators, Tony Yatming Ho

Electronic Theses and Dissertations

Non-reciprocal wave transmission is a phenomenon witnessed in certain photonic devices when the wave propagation dynamics through the device along one direction differs greatly from the dynamics along the counter-propagating direction. Specifically, it refers to significant power transfer occurring in one direction, and greatly reduced power transfer in the opposite direction. The resulting effect is to isolate the directionality of wave propagation, allowing transmission to occur along one direction only. Given the popularity of photonic integrated circuits (PIC), in which all the optical components are fabricated on the same chip so that the entire optical system can be made more …

A Fitness Function Elimination Theory For Blackbox Optimization And Problem Class Learning, Gautham Anil

Electronic Theses and Dissertations

The modern view of optimization is that optimization algorithms are not designed in a vacuum, but can make use of information regarding the broad class of objective functions from which a problem instance is drawn. Using this knowledge, we want to design optimization algorithms that execute quickly (efficiency), solve the objective function with minimal samples (performance), and are applicable over a wide range of problems (abstraction). However, we present a new theory for blackbox optimization from which, we conclude that of these three desired characteristics, only two can be maximized by any algorithm. We put forward an alternate view of …

Leveraging Help Requests In Pomdp Intelligent Tutors, Jeremiah Folsom-Kovarik

Electronic Theses and Dissertations

Intelligent tutoring systems (ITSs) are computer programs that model individual learners and adapt instruction to help each learner differently. One way ITSs differ from human tutors is that few ITSs give learners a way to ask questions. When learners can ask for help, their questions have the potential to improve learning directly and also act as a new source of model data to help the ITS personalize instruction. Inquiry modeling gives ITSs the ability to answer learner questions and refine their learner models with an inexpensive new input channel. In order to support inquiry modeling, an advanced planning formalism is …

Restricting Supervised Learning: Feature Selection And Feature Space Partition, Xiaofei Nan

Electronic Theses and Dissertations

Many supervised learning problems are considered difficult to solve either because of the redundant features or because of the structural complexity of the generative function. Redundant features increase the learning noise and therefore decrease the prediction performance. Additionally, a number of problems in various applications such as bioinformatics or image processing, whose data are sampled in a high dimensional space, suffer the curse of dimensionality, and there are not enough observations to obtain good estimates. Therefore, it is necessary to reduce such features under consideration. Another issue of supervised learning is caused by the complexity of an unknown generative model. …

Standoff Laser Interferometric Photoacoustic Spectroscopy For The Detection Of Explosives, Logan Marcus

Electronic Theses and Dissertations

There will unfortunately always be a pressing need to detect and identify explosive materials. Performing detection at a standoff distance is much safer and this is the impetus for this work. Photoacoustic spectroscopy is well suited to the task of explosive detection at a standoff distance. A detailed theory of the standoff measurement of the physical response of a system to photoacoustic excitation with an interferometric sensor has been constructed and tested. The use of this methodology to measure the standoff photoacoustic spectrum of TNT with an interferometric sensor has clearly been demonstrated. This methodology and the tested theory can …

Tackling Tax Evasion: Transfer Price Manipulation, Extractive Natural Resources And A Strategy For The Southern African Customs Union, Patrick Grant Mclennan

Electronic Theses and Dissertations

An increase in the number of multinational enterprises (MNEs) has increased the attention on cross-border challenges, such as transfer price manipulation (TPM). TPM is a development issue - it undermines institutions as well as siphons money from government revenues that could be directed towards programs for human development. Pervasive corruption in the natural resource sector supports an environment where TPM can flourish. This paper develops a strategy for combating TPM within the countries of the Southern African Customs Union. It does this by 1) defining the terrain of illicit flows, both generally and specifically to the abuse of transfer pricing …

Modeling Of Growth Kinetics And Characterization Of Membrane Mechanics, Antonio Nava

Electronic Theses and Dissertations

One growing field in alternative energy is biofuel production through microorganisms. These fields of research include hydrogen and biofuel production through the cultivation of algae. We've selected 2 different algae, Anabaena sp. cpcc 387 and Tetraselmis to study. Through mathematical modeling of Anabaena we investigate the complex multicellular relationships and colony stability when noise is introduced. In conjunction with researchers at NREL, we've set out to characterize Tetraselmis cells' membrane elasticity.

Accurate Player Modeling And Cheat-Proof Gameplay In Peer-To-Peer Based Multiplayer Online Games, Daniel Everett Pittman Jr.

Electronic Theses and Dissertations

We present the first detailed measurement study and models of the virtual populations in popular Massively Multiplayer Online Role-Playing Games (MMORPGs). Our results show that, amongst several MMORPGs with very different play styles, the patterns of behaviors are consistent and can be described using a common set of models.

In addition, we break down actions common to Trading Card Games (TCGs) and explain how they can be executed between players without the need for a third party referee. In each action, the player is either prevented from cheating, or if they do cheat, the opponent will be able to prove …

New Open Source Software For Building Molecular Dynamics Systems, Bruce Michael Allen

Electronic Theses and Dissertations

The context of this work is the development of open source software to support researchers to quickly build systems of molecules for molecular dynamics (MD) simulations. The goal is achieved through the integration of three open source programs by judicious modifications and creation of new source code, which allows the creation of molecular models, MD cells and the LAMMPS geometry input files. The software changes work together supporting an easy and intuitive process for simulation system creation. Creation of multiple MD cells for research simulations becomes quicker and provides needed standardization to the simulation process. The researcher can select from …

Interferometric, Astrometric, And Photometric Studies Of Epsilon Aurigae: Seeing The Disk Around A Distant Star, Brian Keith Kloppenborg

Electronic Theses and Dissertations

Epsilon (ε) Aurigae is a binary star system that has baffled astronomers for 170 years. In 1821 it was first noticed that the star system had dimmed by nearly 50%. After many decades of photometric monitoring, the 27.1 year period was finally established in 1903. A few years later, in 1912, Henry Norris Russell published the first analytic methods for binary star analysis. Later application of these formulae came to an interesting conclusion; the system was composed of two stars: the visible F-type supergiant, and an equally massive, but yet photometrically and spectroscopically invisible, companion.

Several theories were advanced to …