Digital Commons Network^™

A Systemic Approach To Maximize Heterogeneous System Performance, Thomas L. Randall

All Dissertations

Continuous increases in high performance computing (HPC) throughput have served as catalysts for industry and scientific advancement in countless manners that have fundamentally shaped our modern world. Our demands on compute resources continue to scale, but the limitations of Ahmdal’s law and Dennard scaling have proven increasingly difficult to overcome when approached solely through hardware or software design. Furthermore, many HPC applications fail to utilize the collective system’s performance, even on the most advanced supercomputers.

However, the resurgence of AI in the industry has promoted an explosion of hardware and software codesign that have fueled massive improvements in GPU design …

Domain Decomposition For Coupled Systems Of Fluid-Structure Interaction And Numerical Modeling For Thin Film Polymers, Amy De Castro

All Dissertations

We consider two primary areas of physical application in this work: fluid interaction systems with either linear elastic structures or with poroelastic structures, and thin film polymers, where the majority of the work focuses on the fluid-structure interaction systems.

In the first chapter, we present a strongly coupled partitioned method for fluid structure interaction (FSI) problems based on a monolithic formulation of the system which employs a Lagrange multiplier (LM). We prove that both the semi-discrete and fully discrete formulations are well-posed. To derive the partitioned scheme, a Schur complement equation, which implicitly expresses the Lagrange multiplier and the fluid …

Investigate The Use Of Nucleic Acids As Pesticides To Manage Major Pests And Pathogens Of Crops In South Carolina, Prasanna Valavanur Shekar

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The sugarcane aphid (SCA, Melanaphis sorghi), first discovered on grain sorghum in late 2013, has gradually become a major insect pest of sorghum. It inflicts significant damage to the crop year after year, causing millions of dollars in losses throughout the sorghum-producing regions of the United States. Similarly, Armillaria root rot—also referred to as oak root rot—is a major cause of decline in peach (Prunus persica) production in the southeastern United States. This disease is caused by Armillaria mellea and Armillaria tabescens. Current management practices for controlling M. sorghi include the use of synthetic pesticides, resistant varieties, and regular scouting. …

Enhancing Photovoltaic Inverter Reliability Through Advanced Hardware Protection And Simulation Techniques, Buck Brown

All Dissertations

Power electronics converter reliability is an issue in today’s grid, and it is an issue that will only become more prevalent as the nation and world move toward greater renewable energy penetration. While a significant amount of research has been conducted pertaining to power electronics converter reliability, (1) there lacks a universal way to protect the most critical component in a power electronics converter—the power device—from the two most common failure modes—short- and open-circuit faults; and (2) there does not exist a tool that considers both the component- and system-levels of a photovoltaic (PV) inverter for the purposes of lifetime …

Design And Characterization Of Lignin-Based, Thermoresponsive Soft Composites With Improved Mechanical And Transport Properties, Missoury D. Wolff

All Dissertations

In an attempt to reduce reliance on petroleum-based polymers, lignin – an abundant biopolymer – has gained popularity as a sustainable alternative. However, research on lignin-containing soft composites – i.e., hydrogel (bio)composites – has largely been heuristic, providing limited insight into the fundamental structure-processing-property relationships that govern performance improvements in this emerging class of ‘green’ soft composites. As such, this dissertation presents a systematic investigation of how lignin molecular weight (MW), composite composition, and the concentrations of crosslinker and accelerator impact the mechanical and transport characteristics of soft composites composed of lignin, poly(N-isopropylacrylamide) (PNIPAm), and poly(vinyl alcohol) (PVA).

In the …

Understanding Conversion Of Long Chain Fatty Acids In Anaerobic Digestion Systems, Julia Ann Funk

All Dissertations

Anaerobic co-digestion with fats, oils, and grease (FOG) waste can increase energy production due to the high methane potential of lipids. However, adding FOG can lead to operational issues caused by accumulating saturated long-chain fatty acids (LCFA). My research explored why saturated LCFAs are often the primary intermediate that accumulates and the microbial sensitives of the populations responsible for their degradation. In each batch or semi-continuous experiment, all intermediates of FOG degradation, including LCFAs, volatile fatty acids (VFAs), Hydrogen gas (H₂), and endpoint methane production, were paired with temporal quantitative polymerase chain reaction (qPCR) of the Syntrophomonas genus …

Ultrafast Laser Surface Structuring For Wettability Control On Copper, Akshay Arvind Nagvenkar

All Theses

Wettability is a crucial surface property influencing various phenomena, including heat transfer, cell adhesion, and corrosion. Engineering devices can achieve superior performance by precisely manipulating surface wettability. As a result, extensive research has focused on developing surfaces that exhibit either extreme water attraction (superhydrophilic) or strong water repellency (superhydrophobic). Tailoring surface wettability paves the way for numerous applications, such as drag reduction in marine vessels, controlled drug delivery, efficient water collection, advanced liquid transport systems, oil-water separation, anti-corrosion coatings, friction reduction, and self-cleaning materials. Ultrafast laser surface structuring is a promising approach for engineering multifunctional surfaces, effectively modifying material properties …

Reinforcement Learning For High-Dimensional Tradespace Exploration In Multi-Objective Optimization, Aaditya Kothavade

All Theses

Engineering design optimization often requires balancing multiple competing objectives while navigating complex, high-dimensional tradespaces. Despite significant advances in tradespace exploration techniques, current methods face critical challenges in efficiently navigating high-dimensional design spaces. As the number of design variables and competing objectives increases, traditional multi-criteria decision-making and optimization methods struggle to explore the vast solution space comprehensively. The curse of dimensionality exacerbates this issue, making it impractical to analyze all possible solutions and effectively identify trade-offs between objectives. Additionally, the computational complexity of high-dimensional spaces further complicates optimization, making exhaustive solution analysis infeasible. Traditional multi-objective optimization methods rely on static Pareto-front …

Stability Of Holes In Granular Raft, Plabon Kumar Saha

All Theses

A granular raft at an oil–water interface exhibits unique mechanical properties, including the ability to form and sustain stable holes. In this study, we experimentally investigate the formation, stability, and collapse dynamics of holes in particle rafts composed of micrometer-sized particles. Holes are created using a hollow cylinder, which generates a meniscus that inhibits particle motion, thus stabilizing the hole. Stable holes are formed when their size reaches a critical value, which depends upon the capillary length. The critical hole size does not depend upon the circularity of the hole. We show that capillary forces due to the presence of …

False Information Attack Detection In A Connected Vehicle Environment With Quantum Inspired Long Short-Term Memory, Jean Michel M. Tine

All Theses

Wireless communication Systems enabling Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) data exchange, supported by technologies such as Cellular-V2X (C-V2X), has introduced significant cybersecurity challenges, particularly the threat of false information attacks that can compromise traffic safety and efficiency. In this thesis, the author focuses on identifying false information cyber-attack on V2I, in which vehicles are sending Basic Safety Messages (BSMs) to a Roadside Unit (RSU) and RSUs are collecting, processing and communicating data back to Connected Vehicles (CVs) to support different CV applications. Despite advances in anomaly detection using Long Short-Term Memory (LSTM) networks, these models often struggle with computational efficiency …

Characterizing Xylella Fastidiosa Pathogen Dynamics On Diverse Small Fruit Farms, Alexandra Ratay

All Theses

Global agriculture has been threatened for over a century due to the emergence of the plant pathogenic bacteria Xylella fastidiosa (Lysobacterales: Lysobacteraceae) (Xf). Xf comprises five main subspecies and induces severe physiological symptoms in a diverse set of host plant species by limiting xylem function. Xylem-feeding insect vectors can transmit Xf to host plants, spreading disease and reducing fruit yield. Here I studied Xf prevalence on small fruit farms to determine Xf host plant and vector infective status to the Xf subspecies level. I detected Xf in 28 host plants in South Carolina containing either Xf subspecies fastidiosa …

Quantifying The Transformation Of The Built Environment As A Result Of Cooper River Bridge Construction In Charleston, South Carolina, Catherine Claire Jackson

All Theses

The demolition of historically undervalued vernacular architecture for the construction of transportation projects has created a large-scale, cumulative loss of architectural heritage nationwide. This thesis quantifies the architectural loss caused by the construction of the series of Cooper River bridges in peninsular Charleston and Mount Pleasant. This study assesses the transformation of the built environment as a result of each bridge’s construction by determining the quantity of architectural loss, identifying forms and materials of architectural loss, and differentiating the effects of bridge construction on the more rural Mount Pleasant side compared to the urban peninsular Charleston side. Also assessed in …

Resurrecting Mslrp The Diagnosing, Documentation, And Demonstration Of Miniaturized Sequential Liquid Lignin Recovery And Purification, Robert Booth Whiting Lowery Jr

All Theses

A pilot plant designed for the Sequential Recovery and Purification of Liquid Lignin was downsized to perform optimization and minor adjustments at a reasonable time and operational cost. Multiple failed runs proved the need for a redesign, and an analysis was performed to solve the newly discovered scaling issues.

Operators identified several common failure points of the mSLRP and theorized several methods to rectify them. This included a rework of both procedural elements, the physical construction of the pilot plant, and the actual code and control of the pilot plant’s operating system, LabVIEW.

Runs were attempted, and eventually, the corrective …

Assessing Student Satisfaction Using Courses Generated By Artificial Intelligence, Althaf Hussain Kallamadugu

All Theses

This research explores the effectiveness of using Artificial Intelligence (AI)-generated voice-over presentations as an alternative to traditional human-narrated lectures in online education. The study focuses on students preparing for the Federal Aviation Administration (FAA) Part 107 exam for Commercial small Unmanned Aircraft Systems (sUASs). By comparing AI-generated lectures with human-narrated content, the research aims to assess the impact of AI on student satisfaction, engagement, and performance. A mixed-methods approach was employed, combining quantitative analysis of exam scores and survey data with qualitative insights from student interviews. The methodology includes the creation of AI-generated voice-over presentations, survey distribution to both control …

Modality Distillation Using A Sam-Guided Multimodal Teacher For Unimodal Wildfire Segmentation And Temperature Prediction, Michael N. Marinaccio

All Theses

Wildfires are one of the world’s most devastating natural disasters that affect the environment, communities, and more critically, humans that live in and around those communities. Due to the threat of large-scale destruction in landscapes and human inhabited areas, it has become increasingly more important to develop wildfire detection, management, and suppression strategies to mitigate and prevent these negative outcomes. Wildfire research encompasses many different areas. Most notably, the development of communication, navigation, remote sensing, and monitoring systems. In wildfire monitoring, limitations discovered in-ground and satellite observation have shifted the focus toward Unmanned Aerial Vehicle (UAV) based wildfire research, which …

Micro Wind Turbine - Modelling And Testing, Mohammad Uzair Bhati

All Theses

The global energy demand continues to rise as people consume more electricity to power their personal electronics, electric vehicles, and consumer products such as outdoor tools. To generate renewable energy, large scale solar and wind farms continue to receive the most commercial attention. However, portable wind energy turbines have the potential to generate sufficient power for cell phones and other electronic devices. There are two types of wind turbines, horizontal and vertical axis each having their pros and cons. Vertical-axis wind turbines are the main focus of this thesis, with a reduction in their form factor or size and portable …

Lightlink: Visible Light Communication For Batteryless Devices With Variable Computational Load, Charles Phillips

All Theses

Visible Light Communication (VLC) devices have been experimentally proven to work as a suitable communication medium for batteryless devices. However, the effects of practical load have yet to be fully explored. To that end, we have developed LightLink, a new MAC and PHY layer protocol for VLC within batteryless devices, and have studied various ways that computational load can affect transmission accuracy in realistic scenarios. Our key findings point us towards an adaptive VLC reception system based on inferred environmental variables.

Evaluating Climate Benefits In The Conservation Reserve Program: Methane Emissions And Carbon Storage In Restored Wetlands, Annika Kuleba

All Theses

As climate change progresses, Nature-based Climate Solutions (NbCS) have emerged as a key strategy for mitigation. Historically, wetlands were drained to increase arable land area, resulting in habitat degradation and soil erosion. To address these issues, the United States Department of Agriculture (USDA) incentivizes wetland restoration under the Conservation Reserve Program (CRP), in which landowners retire agricultural land to reestablish native habitat. Although wetlands can act as carbon sinks, they are also sources of methane, a more potent greenhouse gas (GHG). Therefore, the effectiveness of wetlands as a NbCS remains under debate due to assumed high methane emissions. Wetland functions …

Crusade From Afar: British Conservative Revolutionaries And The Nationalist Cause In Spain, Russell Crosthwait

All Theses

The Spanish Civil War catalyzed a distinctive intellectual movement among Britain's interwar right—the Conservative Revolutionaries. This thesis explores how this conflict provided ideological coherence to figures like Arnold Lunn, Arthur Bryant, and Douglas Jerrold, who occupied a unique position between conventional conservatism and fascism. Through organizations such as the Friends of Nationalist Spain, these intellectuals translated their abstract critiques of liberalism, democracy, and industrial capitalism into concrete political action. The thesis demonstrates that these figures were neither simple conservatives nor card-carrying fascists, but proponents of a third way between the two. This study challenges the conventional narrative that portrays British …

Preserving Historic Houses: An Analysis Of Cleaning Methods For The Removal Of Fire Extinguisher Discharge On Historic Finished Plaster, Jessica Lynn Ridder

All Theses

Fire extinguishers are a necessity within any publicly accessible building, and their use is regulated by codes for public safety. When a fire extinguisher is used, the discharge residue can cause damage to the materials it comes into contact with. This potential damage presents an issue for many house museums, as the loss or removal of damaged material may affect the historic integrity of the site. With the ultimate goal of preserving the material integrity of historic sites, the ability to quickly and easily remove fire extinguisher discharge residue can allow materials, such as historic finished plaster, to remain in …

Application Of Remote Sensing In Mapping Callery Pear Distribution And Biomass Estimation In The Southeastern United States, Kavi Raj Awasthi

All Theses

Callery pear (Pyrus calleryana Decne. Rosaceae) is a rapidly spreading invasive species in the southeast United States (US) that hampers the function of native tree species and the forest ecosystem. Native to Southeast Asia, the species has encroached on the natural and secondary vegetation habitats of the Southern US in recent years. This study attempted to 1) map the Callery pear across the southeast US and 2) model the aboveground biomass (AGB) of individual Callery pear trees.

We used Callery pear locations and winter imageries of Sentinel-2, Sentinel-1, L-band radar, and terrain imagery for mapping purposes. In addition, we …

Impacts Of Cognitive Workload On Veteran Driver Reaction Time: Predictive Modeling Using Bayesian And Machine Learning Methods, Kenneth Ofosu-Kwabe

All Theses

In high-demand environments, the ability to manage cognitive workload can mean the difference between optimal or safe performance and critical failure or accidents. Veterans face an elevated risk of fatal motor vehicle accidents due to post-deployment stress, combat-related injuries, and challenges readjusting to civilian driving. This study explores how cognitive workload affects reaction time performance using a driving simulator by collecting and analyzing subjective workload ratings (using the NASA-TLX survey), physiological signals from eye-tracking and performance data from a sample of 28 Veterans.

We examined how task difficulty, cognitive indicators and personal attributes influence reaction times across an interactive driving …

Developing Reduced Order Models For Gas Bubble Formation In Irradiated Metals Using Integrated Phase Field Modeling And Koopman Operator Theory, John M. Eggemeyer V

All Theses

Irradiation damage in materials is prevalent in nuclear components, posing significant risks in the safety and reliability of nuclear reactors. Phase field models offer a versatile framework for modeling irradiation damage in materials at mesoscales. Such high fidelity method has been used to model the formation of fission gas bubbles superlattice, a microstructure array occurs at certain irradiation conditions (dose, dose-rate, and temperature). To overcome the high computational cost of phase field modeling, Koopman operator theory is applied to create reduced order models, allowing for instantaneous simulations of fission gas bubble behaviors. These low fidelity models are integrated into machine …

An Experimental And Computational Study Of High-Temperature Creep Behavior In Fully Lamellar Titanium Aluminide Alloys, Karel M. Ziminsky

All Theses

Titanium aluminide alloys have seen increased aerospace applications in recent years, especially in aircraft jet engines. They can offer benefits such as improved high-temperature strength compared to titanium alloys and reduced density compared to nickel alloys. These alloys also can exhibit high creep resistance due to their fully lamellar microstructure. These mechanical properties are desirable for components like turbine blades, where tight tolerances must be maintained for optimal performance. This research examines the high-temperature creep behavior of a fully lamellar two-phase titanium aluminide alloy, TNM® (Ti-43.5Al-4Nb-1Mo-0.1B), through experimental and computational methods. Scanning electron microscopy studies reveal the presence of large …

The Effect Corrugated Fiberboard Has On The Environment In Terms Of Compostability, Plant Growth, And Per-And-Poly-Fluoroalkyl Substance Contamination, Meredith Clem

All Theses

The “Lasagna Method” is a popular and sustainably perceived technique that many gardeners use as a free and convenient method to dispose of cardboard (corrugated fiberboard) packaging while also improving their gardens. Many claim that this creates benefits for your garden, but many others have proposed their concerns, including the safety of the practice. This research analyzes the compostability of cardboard, the effect it has on plant growth and development of lettuce, and its contamination of a prominent chemical that has known negative effects on human health. The results of these studies showed that cardboard, as it is currently produced …

Evaluating The Role Of Electrostatic Forces In The Adsorption Of Perfluoroalkyl Substances To Granular Activated Carbon, Thomas A. Mccall

All Theses

In response to new drinking water regulations announced by the EPA in 2024, many municipalities will need to monitor concentrations and implement new treatments to address PFAS, a class of anthropogenic organic contaminants. A leading technology for this application is GAC adsorption due to its familiarity and availability. The adsorption of four PFAS species (PFBA, PFBS, PFOA and PFOS) to Calgon Filtrasorb400 (F400) was evaluated for a range of pH and ionic strength conditions to investigate the role of electrostatic interactions in adsorption capacity. These PFAS are all strong acids, so pH was used as a control for GAC surface …

Tsunamigenesis On A Buoyant Granular Layer As A Model Of Ice Mélange In Ice-Choked Fjords, Nathan F. Reyner

All Theses

Glacial calving events can often create destructive tsunami waves in ice-choked fjords in the arctic region, posing a threat to local inhabitants and damaging coastlines. Here the sea is covered by a polydisperse granular material called ice mélange, whose properties can affect the wave characteristics. To investigate the role of a buoyant granular layer, as a model of ice mélange, on tsunami generation, or tsunamigenesis, a series of laboratory experiments were conducted by collapsing a column of dense granular material into a body of water with a layer of buoyant particles distributed across the liquid surface. Experiments were performed over …

Graph Based Deep Reinforcement Learning Aided By Transformers For Multi-Agent Cooperation, Michael S. Elrod

All Theses

Mission planning for a fleet of cooperative autonomous drones in applications that involve serving distributed target points, such as disaster response, environmental monitoring, and surveil- lance, is challenging, especially under partial observability, limited communication range, and uncertain environments. Traditional path-planning algorithms struggle in these scenarios, particu- larly when prior information is not available. To address these challenges, I propose an innovative framework that integrates Graph Neural Networks (GNNs), Deep Reinforcement Learning (DRL), and transformer-based mechanisms for enhanced multi-agent coordination and collective task ex- ecution. My approach leverages GNNs to model agent-agent and agent-goal interactions through adaptive graph construction, enabling efficient …

Investigating The Influence Of Animation And Conversational Virtual Agent Features On The Usability And User Experience Of The Smartphone Mental Health Application “Airheart”, Victoria Hill

All Theses

Rates of depression in college students have skyrocketed since the beginning of the COVID-19 pandemic, reflecting a need for effective, accessible mental health interventions. One potential intervention includes mental health (MHealth) apps. Virtual agents within MHealth apps may represent one way to provide human-like connection and therapeutic benefits. Despite the abundance of MHealth apps currently available for public use, few include virtual agents. Moreover, it is unclear which virtual agent features within mental health apps may be particularly beneficial in providing a positive user experience. The current study sought to evaluate how features of virtual agents, such as animation and …

Community Wastewater Treatment Resilience Assessment, Tristan Veal

All Theses

With the rising threat of climate change and cascading impacts from infrastructure failure there is a growing need to strengthen community resilience. Theoretical and practical resilience frameworks are available, but they vary in aim and scope; there is no standard tool to assess resilience. This research expands on the resilience matrix (RM) application methods of previous research completed by the United States Army Corps of Engineers (USACE) and Clemson University. That work focused on drinking water treatment systems and developed a few dozen specific indicators, or metrics, to quantify resilience. This research adds wastewater infrastructure with the aim of identifying …