Digital Commons Network^™

A Numerical Method For The Navier Stokes Equations In A Velocity-Vorticity Form, Liang Zhao

All Dissertations

In physics, the Navier-Stokes equations (NSE) describe Newtonian fluid flows. Instead of focusing on the standard NSE with velocity and pressure as primary variables, we are interested in the Navier Stokes equations in a velocity-vorticity form (NSE-VV). In NSE-VV, vorticity is included in the system as an independent variable so that it can be computed directly. The main contribution of this thesis is proposing a numerical method for solving NSE-VV, which includes an efficient solver, an adaptive mesh refinement strategy and error analysis. A nested solver plays a fundamental role in the numerical method of NSE-VV. Similar to how it …

Influence Of Consumer Involvement In Tourist Information Search: Application Of Economics Of Information Theory In A Destination, Peter Judca Mkumbo

All Dissertations

In the modern digital world, it is increasingly challenging for destination marketers to design integrated marketing communication (IMC) strategies. The spectrum of information sources has become broader, serving for wider market interests. The importance of information in the modern world is increasing exponentially, and the tourism industry is traditionally information intense. There is an endless list of information outlets, and it is impossible to be present in all the information platforms. The spectrum of outlets includes old-school prints like magazines and newsletters on the one hand, while on the other hand there are modern advanced Web 2.0 technologies like social …

Experiences Of Upstate South Carolina Historical Preservationists: Wisdom For Cultivating Future Advocates, Steven Clay Pruitt

All Dissertations

Current literature has suggested that despite scholars in other fields gleaning vast amounts of experimental data to use to hone curriculum decisions and support their disciplines, researchers in social studies education have failed to look at Significant Life Experiences (SLEs) of Historical Preservationists (HPs) for the same benefit. The American Historical Association (AHA) cited a twenty-one percent dip in history majors since 2012 (Townsend, 2017), historic sites like Colonial Williamsburg have been hit by a lack of interest and visitation from the public (Tiedemann & Marsico, 2017), and many local historical associations and community museums have uncertain futures due to …

Trust-Based Control Of Robotic Manipulators In Collaborative Assembly In Manufacturing, Behzad Sadrfaridpour

All Dissertations

Human-robot interaction (HRI) is vastly addressed in the field of automation and manufacturing. Most of the HRI literature in manufacturing explored physical human-robot interaction (pHRI) and invested in finding means for ensuring safety and optimized effort sharing amongst a team of humans and robots. The recent emergence of safe, lightweight, and human-friendly robots has opened a new realm for human-robot collaboration (HRC) in collaborative manufacturing. For such robots with the new HRI functionalities to interact closely and effectively with a human coworker, new human-centered controllers that integrate both physical and social interaction are demanded. Social human-robot interaction (sHRI) has been …

Modelling The Effects Of Disease-Associated Single Amino Acid Variants And Rescuing The Effects By Small Molecules, Yunhui Peng

All Dissertations

Single nucleotide polymorphism (SNP) is a variation of a single nucleotide in the genome. Some of these variations can cause a change of single amino acid in the corresponding protein, resulting in single amino acid variation (SAV). SAVs can lead to profound alterations of the corresponding biological processes and thus can be associated with many human diseases. This dissertation focuses on integration of existing and development of new computational approaches to model the effects of SAVs with the goal to reveal molecular mechanism of human diseases. Since proton transfer and pKa shifts are frequently attributed to disease causality, the proton …

Hydrothermal Crystal Growth Of Tetrahedral Framework Oxides For Optical Applications, Rylan James Terry

All Dissertations

In our modern world, lasers are used every day, from the mundane task of playing a DVD to the innovative implementation of laser surgery. Nonlinear optical (NLO) crystals are crucial to laser technology for their ability to modify the frequency of a beam. The development of new NLO crystals is necessary for the advancement of laser technology, in order to reach wavelengths that are not currently accessible due to the limitations of current materials. Of particular importance to semiconductor photolithography, laser micromachining, and scientific instrumentation are the ultra-violet (UV, 200 nm > λ > 400 nm) and deep-UV (λ < 200 nm) portions of the optical spectrum. This dissertation delves into the synthesis of new potential NLO materials by means of hydrothermal crystal growth. In this study, tetrahedral oxides are utilized due to their likelihood of producing noncentrosymmetric (NCS) crystals, a necessity for NLO materials. Silicates are also employed in this study due to their particularly deep absorption edge into the UV. The addition of a spectroscopically silent rare earth ion which is capable of being doped with a lasing ion into a NCS crystal may lead to a single crystal that is both capable of lasing and frequency doubling. In the pursuit of such a crystal, the novel syntheses of Cs3YSi6O15 and LiRESiO4 (RE = Er, Tm, Yb, Lu) were established. Although these materials proved not to be NCS, their structures proved very intriguing and in the case of Cs3YSi6O15 is the parent structure to a family of structures that otherwise exhibits structural disorder or modulation. In expanding the range of mixed oxoanion species, the rare earth ion was replaced with a tetrahedral trivalent oxoanion. The appeal of a series with the general formula ABCO4, (A = alkali ion, B = trivalent metal, and C = tetravalent metal) is its prevalence to produce NCS crystals, notably having a tridymite-type framework. Tridymite is a high temperature variant of quartz that forms six-membered rings propagating through the structure, creating vacant channels. In a stuffed variation of this structural type, rings having negative charge are balanced by the “stuffing” of an alkali or alkaline earth cation into the vacant channels. While the archetype of the stuffed tridymites forms in the centrosymmetric (CS) space group setting of P63/mmc, there are four degrees of freedom that evolve as small variations in the structure are made, often leading to the removal of the inversion center. With the synthesis of a wide array of crystals in this family, those that were found to be NCS were analyzed for their potential use as NLO materials.

High-Throughput Polygenic Biomarker Discovery Using Condition-Specific Gene Coexpression Networks, William Louis Poehlman

All Dissertations

Biomarkers can be described as molecular signatures that are associated with a trait or disease. RNA expression data facilitates discovery of biomarkers underlying complex phenotypes because it can capture dynamic biochemical processes that are regulated in tissue-specific and time-specific manners. Gene Coexpression Network (GCN) analysis is a method that utilizes RNA expression data to identify binary gene relationships across experimental conditions. Using a novel GCN construction algorithm, Knowledge Independent Network Construction (KINC), I provide evidence for novel polygenic biomarkers in both plant and animal use cases.

Kidney cancer is comprised of several distinct subtypes that demonstrate unique histological and molecular …

Magnolia: Impact Of Interspecific Hybridization On Genetic Variation And Ongoing Breeding Initiatives, James Kevin Parris

All Dissertations

The genus Magnolia comprises over 250 species naturally occurring in Eastern North America, Central America, South America, islands of the Gulf of Mexico, and Eastern Asia. A long history of cultivation and breeding going back to the early nineteenth century reveals a common trend of reproductive compatibility throughout this group of basal angiosperms. Interspecific hybridization has led to plethora of ornamental cultivars that have proven adaptable to natural and cultivated habitats beyond the range of each species. Understanding of taxonomic relationships between species has evolved as observations of morphological characteristics and genetic analyses have been more thoroughly investigated. The objectives …

Investigating The Use Of Streaming And Robotic Dielectrophoresis To Enable Continuous Cell Sorting And Automatic Cell Transfer In Sample Preparation, Rucha Natu

All Dissertations

The sorting of targeted cells or particles from a sample is a crucial step in the sample preparation process used in medical diagnosis, environmental monitoring, bio-analysis and personalized medicine. Current cell sorting techniques can be broadly classified as label based or label-free. Label-based techniques mostly rely on fluorophores or magnetic nanoparticles functionalized to bind with targeted cells. Although highly specific, this approach can be expensive and suffers from limitations in the availability of suitable markers. Label-free techniques exploit properties inherent to the cell, such as density and size, to simplify the sorting protocol and reduce cost by eliminating the need …

Taxonomic, Genetic And Functional Diversity Of Symbionts Associated With The Coastal Bivalve Family Lucinidae, Jean S. Lim

All Dissertations

Extant bivalve members from the family Lucinidae harbor chemosynthetic gammaproteobacterial gill endosymbionts capable of thioautotrophy. These endosymbionts are environmentally acquired and belong to a paraphyletic group distantly related to other marine chemosymbionts. In coastal habitats, lucinid chemosymbionts participate in facilitative interactions with their hosts and surrounding seagrass habitat that results in symbiotic sulfide detoxification, oxygen release from seagrass roots, carbon fixation, and/or symbiotic nitrogen fixation. Currently, the structural and functional complexity of whole lucinid gill microbiomes, as well as their interactions with lucinid bivalves and their surrounding environment, have not been comprehensively characterized. This dissertation focuses on the taxonomic, genetic, …

Fabrication And Mechanical Properties Of Micro-Architectured 3d Scaffolds, Pooya Niksiar

All Dissertations

Freeze casting is a physical process for the fabrication of porous anisotropic materials. In this method, an aqueous slurry of ceramic particles is frozen directionally, creating lamellar columns of ice that push particles between the growing crystals. Then, the frozen material is lyophilized to remove the ice and sintered to densify the ceramic. Scaffolds made by freeze casting often have significant strength in the solidification direction, while they lack sufficient strength in the transverse direction. To enhance strength in the transverse direction, magnetite particles are added to a slurry of paramagnetic particles, and an external magnetic field is applied during …

Chemically Active Rheological Modifiers For The Improved Clinical Use Of Cyanoacrylates, Kyle Joseph Garcia

All Dissertations

Over 100 million surgical incisions, 50 million traumatic wounds, and 20 million minor lacerations from cuts and grazes are treated globally each year. One study determined that globally internal and external wounds occur for 40% and 37% of cases respectively for a total of 111 million patients that were treated for wounds. The remaining 23% of patients were treated for minor lacerations and trauma in the emergency room. These wounds require immediate medical attention including pressure application, sutures, clips, tissue cautery, and/or topical hemostatic agents to cease hemorrhage or the exit of other bodily fluids. With blood flow ceased, wound …

An Interpretative Phenomenological Study Of College Women Who Participate In High-Risk Drinking, Their Perceptions Of Drinking Norms, And The Influence Of Those Norms On Their Drinking Behaviors, Elizabeth Leeman Carter

All Dissertations

High-risk alcohol use on college campuses is associated with several negative consequences for students. Social norms campaigns are a widely used intervention aimed at decreasing high-risk alcohol use in a university population but their efficacy can vary based on students’ peer groups and gender. Research on gendered drinking norms for college students tends to focus on men, as they are usually identified as more likely to drink alcohol overall and to drink in high-risk ways. Additionally, social norms campaigns implemented in a small group setting, which aim to correct misperceptions of students who may not initially identify with norms of …

Computational Approaches To Understanding Structure-Function Relationships At The Intersection Of Cellular Organization, Mechanics, And Electrophysiology, Tyler George Harvey

All Dissertations

The heart is a complex mechanical and electrical environment and small changes at the cellular and subcellular scale can have profound impacts at the tissue, organ, and organ system levels. The goal of this research is to better understand structure-function relationships at these cellular and subcellular levels of the cardiac environment. This improved understanding may prove increasingly important as medicine begins shifting toward engineered replacement tissues and organs. Specifically, we work towards this goal by presenting a framework to automatically create finite element models of cells based on optical images. This framework can be customized to model the effects of …

Interfacing The Liquid Sampling- Atmospheric Pressure Glow Discharge Ion Source With Orbitrap Mass Spectrometers For High Accuracy High Precision Isotope Ratio Measurements Of Uranium, Edward Dexter Hoegg

All Dissertations

The integration of the liquid sampling – atmospheric pressure glow discharge (LS-APGD) with Orbitrap mass spectrometers has led to a potential paradigm shift in the field of high certainty isotope ratio measurements. Since the dawn of the atomic age, mass spectrometry has played a critical role in performing isotope ratio measurements of uranium (U), plutonium (Pu) and other radionuclides. Traditionally, these measurements have been made using thermal ionization mass spectrometry (TIMS) instruments and, more recently, inductively coupled plasma mass spectrometry (ICP-MS) instruments. While the ability of these instruments to perform isotope ratio measurements with a high degree of certainty has …

Additive Manufacturing Of Ceramics With Multiscale Heterogeneous Microstructure, Yuzhe Hong

All Dissertations

The additive manufacturing (AM) of ceramic has gained significant attentions because of the difficulties in fabricating hard and brittle ceramics into complex geometry. In addition, AM provides the possibility of fabricating ceramic parts with heterogeneous microstructure on the multiscale, which cannot be achieved using the traditional methods. In today’s AM technologies, ceramics are often extruded for form a green body and then fired to a high density. However, two challenges are faced by the extrusion-based AM of ceramics with multiscale features. One is to depositing ceramics with submicrometer thickness. The other one is to embed microchannels in large-scale ceramic parts. …

Galactic Chemical Evolution And Radioactivities In The Early Solar System, Michael Joseph Bojazi

All Dissertations

A proper accounting for the inferred abundances of the roughly 10 short-lived radioactivities in the early Solar System requires a comparison to their expectations from an appropriate model of Galactic chemical evolution (GCE) (e.g., [115]). Because the timescale for mixing between phases in the interstellar medium (ISM) is comparable to the lifetime of many of the short-lived radioactivities, the GCE model should follow different ISM phases and the mixing between them. The model must also account for the long temporal distance between the rare astrophysical events that produce many of the short-lived species, such as mass transfer from a low-mass …

High-Achieving, Non-First-Generation, Female, Undergraduate Student Views Of Family Influence On Career Decisions, Katryna Bower Maxwell

All Dissertations

This qualitative study sought to understand how high-achieving, non-first-generation, female, undergraduate students viewed the influence parents and families had on their career decisions. This study’s six participants were students in the same honors college at a large, four-year, public university in the Southeast United States. Data from a pre-interview survey, initial interview, in-depth interview, and interview observation protocols were used to understand participants’ career decision-making processes and the influence their parents and families had on those processes. Thematic coding was used to identify three common themes found among participants: (a) parent and family support (b) family influence on career decision-making …

Cases Of Contingent Stem Faculty Who Practice Critical Pedagogies With/In The Neoliberal University, Jeffrey Michael Kenney

All Dissertations

An increasingly neoliberal university means diminishing resources and labor security for those located in the lowest echelon, particularly those engaged in critical/radical/activist projects. The purpose of this study was to generate knowledge in an effort to sustain and advance critical pedagogical practices in college teaching. This study focused principally on the knowledge and insights of contingent STEM faculty who practice critical pedagogies in the neoliberal conditions of public universities. Utilizing critical and pragmatic perspectives, I explored both the ingenuity and practicality of the participants’ praxis as well as examined the structural machinations of neoliberal capitalism within their teaching and learning …

Improving Deep Reinforcement Learning Using Graph Convolution And Visual Domain Transfer, Sufeng Niu

All Dissertations

Recent developments in Deep Reinforcement Learning (DRL) have shown tremendous progress in robotics control, Atari games, board games such as Go, etc. However, model free DRL still has limited use cases due to its poor sampling efficiency and generalization on a variety of tasks. In this thesis, two particular drawbacks of DRL are investigated: 1) the poor generalization abilities of model free DRL. More specifically, how to generalize an agent's policy to unseen environments and generalize to task performance on different data representations (e.g. image based or graph based) 2) The reality gap issue in DRL. That is, how to …

Forestry And Arboriculture Applications Using High-Resolution Imagery From Unmanned Aerial Vehicles (Uav), Brian A. Ritter

All Dissertations

Forests cover over one-third of the planet and provide unmeasurable benefits to the ecosystem. Forest managers have collected and processed countless amounts of data for use in studying, planning, and management of these forests. Data collection has evolved from completely manual operations to the incorporation of technology that has increased the efficiency of data collection and decreased overall costs. Many technological advances have been made that can be incorporated into natural resources disciplines. Laser measuring devices, handheld data collectors and more recently, unmanned aerial vehicles, are just a few items that are playing a major role in the way data …

Impacts Of Thermal Barrier Coating Morphology And Catalytic Properties On Low Temperature Combustion Engine In-Cylinder Processes, Thomas Powell

All Dissertations

The inherent thermodynamic benefits of Homogeneous Charge Compression Ignition (HCCI) make it a likely choice for meeting the increasing demands of fuel economy legislation. Unfortunately HCCI suffers from reduced combustion efficiency and operational variability due to the buildup of carbon deposits. However, the unique thermo-kinetic nature and thermal sensitivity of Low Temperature Combustion (LTC) provides an opportunity to improve combustion efficiency through manipulation of the in-cylinder thermal environment. This body of work sought to create a wall temperature swing using a thin Thermal Barrier Coating (TBC) to reduce combustion heat transfer and improve LTC combustion and thermal efficiencies. The first …

Using Contextual Information To Improve Hidden Markov Model Recognition Of Wrist Motions During Eating Activities, Yiru Shen

All Dissertations

This dissertation considers the problem of recognizing wrist motions during eating. The wrist motion is tracked using accelerometer and gyroscope sensors worn in a watch-like device. The goal is to recognize a set of gestures that commonly occur during eating, such as taking a bite of food or consuming a drink of liquid. The wrist motion during a bite may consist of picking up a morsel of food, moving it the mouth for intake, and returning the hand to a rest position. Hidden Markov models (HMMs) are used to recognize these motions. An HMM is a doubly stochastic process where …

N-Alkyl Methacrylate Polymeric Memristors For Synaptic Response Modeling: Organic And Biologically Relevant Thin Films, Tucker Mcfarlane

All Dissertations

There is a strong interest in organic materials for electrical devices due to several advantages that organic systems have over their inorganic counterparts including ease of processability and lower toxicity. Many of these organic materials can be utilized in the creation of thin-film devices that can be formed in high-throughput processes and with a very small profile. One such device that has emerged in recent years is the memristor which can be used in new computational concept or as a synaptic model. This work studies the alternating current (AC) and direct current (DC) electrical response of a number n-alkyl methacrylate …

Study Of Cables In The Distribution System: Parameters Calculation, Fault Analysis, And Configuration Optimization, Bin Sun

All Dissertations

Underground cables offer more advantages than overhead lines since cables are better protected and do not detract from the appearance of urban areas. In recent years, more and more electrical utilities are using cables to distribute electric power to their customers. However, the cost of installation and maintenance of underground cables is very expensive. Thus, the proper design and operation of distribution systems are crucial for economic reasons. To design and operate the distribution system properly, analysis of the underground cable system is extremely important. The objective of this dissertation is to analyze the underground cable distribution system under both …

Transparent Conductive Films Based On Polymer-Encapsulated Graphene Oxide Sheets, Mykhailo Savchak

All Dissertations

Transparent conductive films (TCFs) play a key role in number of devices, including solar panels, LCD/OLED displays and touchscreens. Graphene has emerged as a promising material in this area due to its unique mechanical and electrical properties. Despite noteworthy progress in the fabrication of large-area graphene sheet-like nanomaterials, the vapor-based processing still requires sophisticated equipment and a multistage handling of the material. An alternative approach to manufacturing functional graphene-based films includes the employment of graphene oxide (GO) micron-scale sheets as precursors. However, search for a scalable manufacturing technique for the production of high-quality GO nanoscale films with high uniformity and …

Cyber Physical System Security — Dos Attacks On Synchrophasor Networks In The Smart Grid, Xingsi Zhong

All Dissertations

With the rapid increase of network-enabled sensors, switches, and relays, cyber-physical system security in the smart grid has become important. The smart grid operation demands reliable communication. Existing encryption technologies ensures the authenticity of delivered messages. However, commonly applied technologies are not able to prevent the delay or drop of smart grid communication messages. In this dissertation, the author focuses on the network security vulnerabilities in synchrophasor network and their mitigation methods. Side-channel vulnerabilities of the synchrophasor network are identified. Synchrophasor network is one of the most important technologies in the smart grid transmission system. Experiments presented in this dissertation …

Subventricular Zone Neural Stem Cells Release Extracellular Vesicles During Early Postnatal Neurogenesis, Mary C. Morton

All Dissertations

Extracellular vesicles (EVs) are nanometer sized particles released from all cells. EVs are found in all biological fluids, including cerebrospinal fluid (CSF) and blood. EVs modulate intercellular communication through the transfer of nucleic acids and proteins from donor to recipient cells. During early postnatal neurogenesis, subventricular zone (SVZ) neural stem cells (NSCs) asymmetrically divide to give rise to neuroblasts that migrate along the rostral migratory stream (RMS) and populate the olfactory bulb (OB). Other, non-neuronal cells populate the SVZ, such as microglia and endothelial cells. Microglia have been shown to regulate SVZ NSCs, but it remains unclear if this communication …

Understanding The Impact Of Racism And Sexism On The Transition Experience Of Black Women Principals From The Classroom To The Secondary School Principalship, Brittany Denise Neely

All Dissertations

This study was focused on understanding how Black women currently serving as secondary school principals were able to obtain their positions and what supports they received and barriers they encountered during their transition from teacher to principal. The underlying purpose behind this study was to understand how racist and/or sexist practices within the educational system influenced their experiences in becoming some of the few Black women currently serving as secondary school principals. In this study, I drew upon Black feminist thought as my epistemological perspective and critical race feminism as my theoretical framework to understand this phenomenon. To investigate this …

Research Exemplars From An Interdisciplinary Healthcare Genetics Program, Rebecca Leigh Myers

All Dissertations

The first chapter of this dissertation provides an overview of the interdisciplinary Healthcare Genetics model, the framework for the studies described in Chapters Two, Three and Four. The model is comprised of five core constructs: Research, Environment, Clinical Practice, Ethical/Legal/Social Implications (ELSI) and Education. Each construct is defined. Chapter One also presents a brief overview of subsequent chapters.

Chapter Two details a biophysical approach to the phenotypic classification of mutations in the 7-dehydroxycholesterol reductase (DHCR7) gene, involved in Smith-Lemli-Opitz syndrome. This study utilized computer modeling to determine the biophysical effects of each mutation on structure and function of the DHCR7 …