Digital Commons Network^™

Ohmic Contacts For Fabrication Of Sic Cmos Devices, Anthony Di Mauro

Graduate Theses and Dissertations

Today’s world of electronics is dominated by semiconductor devices which utilize silicon as their substrate material. Though, silicon is not ideal for semiconductor devices in high-voltage or high-temperature applications. Additionally, the efficiency of silicon devices becomes drastically reduced in nonideal operating conditions. Therefore, finding alternatives to silicon?based devices has been a topic for decades now. A few great candidates to replace silicon devices for said applications include Silicon Carbide (SiC), Gallium Nitride (GaN), and Aluminum Arsenide (AlAs). SiC has grown its reputation as the best candidate, when compared to other potential alternatives, due to its wide bandgap, high operating frequency, …

Gate Driver Design In High-Temperature Cmos Process For Heterogeneous Integration Inside Sic Power Module, Khandoker Asif Faruque

Graduate Theses and Dissertations

The shift toward electrification in transportation, including electric and hybrid vehicles, presents challenges for power electronic converters. Silicon Carbide (SiC) power devices are promising due to their high efficiency, temperature tolerance, and reduced losses compared to traditional silicon devices. However, their use is hindered by issues such as parasitic capacitances and gate inductances, which can lead to voltage spikes and stress on the device gate oxide, hence impacting converter reliability. Increasing gate resistance can help manage these issues, but it reduces switching speed and increases losses. Snubber circuits can mitigate switching stress but add extra components, reducing efficiency. Active gate …

Investigating The Perceived Invisibility Of The Black Woman Leader In Fortune 500 Companies: Understanding Career Pathways Based On Insight And Intersectionality, Shana Jones Yarberry

Graduate Theses and Dissertations

There is a gap in the literature when examining the intersectionality of race, gender, and class. There is additional distance when evaluating the impact each intersection has on the career development of Black Women (BW) in Fortune 500 companies. The purpose of this study was to use a qualitative approach to investigate how the intersectionality of race, gender, and class impact the career advancement of BW while also identifying perceived barriers, historical patterns of career movement, and organizational efforts to support the ascension of BW in senior leadership. The Systems Theory Framework of Career Development and Intersectionality Theory were examined …

Comparing And Evaluating Models Of Tile-Assembly Using Intrinsic Simulation, Daniel Hader

Graduate Theses and Dissertations

Tile-assembly studies abstract models of computation inspired by advancements in the emerging field of DNA-nanotechnology, where synthetic strands of DNA are used as building blocks for microscopic structures. These DNA strands can be made to combine into structural units with selectively sticky sides that abstractly resemble Wang tiles. However, unlike Wang tiles, an assembly process is modeled where tiles combine one-by-one to form larger assemblies according to matching rules based on their sticky sides. While in practice, these tile-assembly models have seen use in designing DNA nano-structures, the mathematical study of their theory has revealed an exciting interplay between geometric …

Exploring The Impact Of Generative Ai Prompt Engineering In Higher Education: A Study In Undergraduate And Graduate Business Analytics Courses, Jana Gastineau

Graduate Theses and Dissertations

The rapid evolution of generative artificial intelligence (GenAI) presents a transformative opportunity in higher education, offering new pathways for learning through personalized feedback, interactive environments, and support for complex tasks. This quasi-experimental study investigated the effects of targeted GenAI prompt engineering instruction on knowledge acquisition, prompt writing skills, and confidence levels among undergraduate and graduate students in business analytics courses at a research university. A pre-test and post-test design measured changes across knowledge acquisition, prompt writing proficiency, and GenAI confidence and usage. Findings revealed a mixed impact on knowledge acquisition, with undergraduates showing minor improvements and graduate students experiencing declines …

Towards Comprehensive And Interpretable Video Understanding, Khoa Vo

Graduate Theses and Dissertations

Video understanding is a critical domain in computer vision, focusing on analysis of sequential visual data to extract meaningful spatiotemporal information for tasks such as action recognition, video captioning, video retrieval, and temporal action localization, etc. Despite significant advancements with spatio-temporal convolutional neural networks and attention-based video models, current methods face limitations, including inadequate representation of main actors, lack of fine-grained modeling of relevant objects, and limited interpretability.
This thesis addresses these challenges by proposing novel approaches that enhance video understanding through modeling interactions among entities (actors and objects) and between entities and the environment, while improving interpretability in the …

Towards Robust And Fair Vision Learning In Open-World Environments, Thanh-Dat Truong

Graduate Theses and Dissertations

The rapid increase of large-scale data and high-performance computational hardware has promoted the development of data-driven machine vision approaches. Advanced deep learning approaches have achieved remarkable performance in various vision problems and are closing the capability gap between artificial intelligence (AI) and humans. However, towards the ultimate goal of AI, which replicates human ability in visual perception tasks, the machine vision learning methods still need to address several ill-posed challenges. First, while the current vision learning methods often rely on large-scale annotated data, the data annotation process is a costly and time-consuming process. Second, the unfaired predictions produced by vision …

Addressing Cybersecurity Data & Workforce Scarcity With Troy: Testbed For Resilient Operational Systems, Henry Oliver Schmidt

Graduate Theses and Dissertations

Machine learning has seen an explosive rise in the past decade. Companies, organizations, and governments are racing to pursue the advancements and insight provided by machine learning powered tools. However, to get effective and meaningful insights from machine learning models a significant amount of detailed data is required to train them. This poses a problem in fields where data is not openly available, such as cybersecurity. Entities are often unwilling to give out network or system data to the public for machine learning and cybersecurity research since that data can contain sensitive or proprietary information. The risk simply outweighs the …

Neural Network Architecture Search Enabled Wide-Deep Learning (Nas-Wd) Integrated Hyperspectral Imaging Understanding For Woody Breast In Poultry Processing, Chaitanya Kumar Reddy Pallerla

Graduate Theses and Dissertations

The development and implementation of a Wide & Deep (WD) learning model tailored for classification and regression tasks utilizing spectral data provides a robust solution to evaluate woody breast (WB) conditions in poultry fillets. This process begins with thorough data preprocessing, which includes loading spectral and classification datasets, imputing missing values with medians, and splitting the data into training and testing sets to ensure rigorous model evaluation. The WD model architecture integrates wide linear models and deep neural networks to harness the strengths of both approaches. The wide component excels at memorizing sparse feature interactions, while the deep component captures …

Intersectionality And Career Persistence Of African American Women In Cybersecurity Careers: A Narrative Inquiry, Monica Marquita Jones Prewitt

Graduate Theses and Dissertations

The purpose of this narrative inquiry is to examine the experiences of African American women working in cybersecurity, a male-dominated field. An intersectional lens will be used in the study to provide insight into their positionality as women of color in a male-dominated career field. The study will examine the stories of the women who persisted in the field and the existing influences or interventions that supported their retention. This pre-registered study will provide the framework for this study to be completed at the University of Arkansas. The researcher will use a descriptive phenomenological approach and semi-structured interviews to understand …

Learning To Accelerate Globally Optimal Solutions: Applications In The Ac Optimal Power Flow Problem, Muhammet Fatih Cengil

Graduate Theses and Dissertations

The Alternating Current Optimal Power Flow (AC-OPF) problem is a fundamental optimization challenge critical to ensuring the economical and reliable operation of power grids. While fast heuristic methods provide upper-bound solutions, assessing their quality requires lower bounds obtained from relaxations of the AC-OPF problem. This dissertation focuses on finding globally optimal solutions to the AC-OPF problem by enhancing the effectiveness and efficiency of Quadratic Convex (QC) relaxations. Leveraging machine learning techniques, we aim to achieve tighter relaxations faster and improve computational performance, enabling practical scalability for real-time applications.

In Chapter 2, we propose a machine learning-based method to accelerate the …

An Investigation Of The Effect Of Performance Engineered Mixture (Pem) Design On Durability And Air Void Matrix Of Concrete Pavements, Jacob Ortlieb

Graduate Theses and Dissertations

Performance Engineered Mixture (PEM) design is a novel method of creating concrete pavement that is economical achieving desirable performance properties such as durability, strength, and workability. Performance-based design is critical for concrete pavements, so the fresh concrete can be placed without issue and the hardened concrete can withstand deterioration and environmental damage such as freezing and thawing. To achieve economical concrete, PEM utilizes tools such as the tarantula curve for aggregate grading, and the Super Air Meter (SAM) test, providing information regarding the air void matrix while the concrete is fresh. To achieve these properties with less cement will lead …

Real-Time Barge Detection Using Traffic Cameras And Deep Learning On Inland Waterways, Geoffery Eyram Agorku

Graduate Theses and Dissertations

Inland waterways are critical for freight movement, but limited means exist for monitoring their performance and usage by freight-carrying vessels, e.g., barges. While methods to track vessels, e.g., tug and tow boats, are publicly available through Automatic Identification Systems (AIS), ways to track freight tonnages and commodity flows carried on barges along these critical marine highways are non-existent, especially in real-time settings. This paper develops a method to detect barge traffic on inland waterways using existing traffic cameras with opportune viewing angles. Deep learning models, specifically, You Only Look Once (YOLO), Single Shot MultiBox Detector (SSD), and EfficientDet are employed. …

Rock Wall Fracturing As A Potential Control On River Valley Width In The Buffalo National River, Arkansas, Kindle Hon

Graduate Theses and Dissertations

Quantifying bedrock properties that control the persistence of fallen rock material (talus) along bedrock walls bounding river valleys may be a key factor in understanding what controls the rate at which these river valleys widen. My work is a component of a collaborative research project focused on the overarching hypothesis that the persistence vs. erodibility of talus that buffers river valley walls can be a first-order control on valley widening rates. I hypothesize that the primary control for creating erodible or persistent talus is the fracture spacing of bedrock valley walls as it sets the maximum block size of collapsed …

Partial Immunity To Mycoplasma Gallisepticum After An Initial Infection Is Long-Lasting And Reduces Transmission In Flocks Of Canaries, Madeline Sudnick

Graduate Theses and Dissertations

Pathology during a second infection can be influenced by immunity and an increase in resistance or tolerance of individuals. Population-level differences in the ability to maintain immunity can lead to contrasting survival outcomes between groups and determine how future outbreaks will spread. However, long term wildlife disease surveillance can be challenging due to lack of infrastructure and host-pathogen specific tests. Calculating disease transmission likelihood requires understanding individual-level heterogeneity in pathology and behavior, and there is limited knowledge in understanding how populations in different stages of an epidemic will transmit disease. In Chapter I, we aim to help fill a gap …

Parallel Degree Planning In The Pursuit Of Academic Success For Pre-Nursing Students In A Competitive Entry Baccalaureate Nursing Programs, Elizabeth L. Mckinley

Graduate Theses and Dissertations

This study sought to understand the student perceptions of parallel academic degree planning for the competitive entry undergraduate Nursing program at a case study university. Parallel degree planning is a relatively new term of alternative curricular planning. The qualitative study includes nine students and their experiences in planning for their intended major while simultaneously planning courses that meet another major or degree program, and understanding how parallel degree planning aided their retention and student satisfaction as well as their academic advisor interaction. The study was completed at a research university where the Nursing program has a very lower acceptance rate, …

An Exploratory Multiple Case Study Of Special Education Transition Program Structures In Virtual Public Charter Schools, Krystle Merry

Graduate Theses and Dissertations

This dissertation research is an exploratory multiple-case study of special education transition program structures in three virtual public charter schools in a southern state in the United States. Virtual public charter schools are extensions of public school systems or districts that are required to comply with state and federal-mandated special education transition services to ensure students with disabilities receive a Free Appropriate Public Education (FAPE) under the Individuals with Disabilities Education Act (IDEA, 2004). This study aims to explore transition Program Structures within the Taxonomy for Transition Programming 2.0 (Kohler et al., 2016) at the systemic level based on the …

Environments And Controls Of Erosional Bedforms In Soluble Channels, Ethan W. Oleson

Graduate Theses and Dissertations

Erosional bedforms, such as scallops, preserve valuable information on the paleohydrologic conditions forming soluble channels in karst systems. While these bedforms are commonly used to interpret past conditions, questions about their formation remain. Mathematical models of speleogenesis in turbulent flow predict that the conditions for forming scallops do not occur in natural carbonate systems. However, scallops are readily found in caves throughout the world. This conundrum has several possible resolutions, but each lacks field-based observations. We present a field-based study of the environments and controls of scallops in gypsum, limestone, and dolostone caves. Our results are based on field observation, …

Influence Of Invasive Species, Drought, And Stream Permanence On Stream Crayfish Species With A Focus On The Imperiled Mammoth Spring Crayfish (Faxonius Marchandi), Leah Marie Bayer

Graduate Theses and Dissertations

Freshwater crayfish constitute one of the most-threatened taxonomic groups in North America. Invasion by other crayfish species as well as habitat degradation through alteration of natural flow regime are two of the most prominent threats to crayfish persistence. Additionally, extreme weather events like droughts can amplify threats posed by other stressors on crayfish populations and are expected to increase in frequency, magnitude, and/or duration in the future, which may negatively influence narrow-ranged endemic crayfish populations typical of the Southeast. The Mammoth Spring Crayfish, Faxonius marchandi, is a narrow-ranged endemic that occurs in the Spring River drainage of Arkansas and Missouri …

Effects Of An Interdependent Group Contingency On Classroom Behavior And Teacher-Student Relationships For Students With Behavioral Support Needs: An Initial Investigation Of Cw-Fit Ms Tier 1 In Inclusive Secondary Settings, Nancy Ruth Young

Graduate Theses and Dissertations

A wide body of literature has documented the disproportionality in exclusionary discipline rates (Gregory et al., 2010; Losen et al., 2015; Office of Special Education Programs, 2020; Skiba, 2014; Welsh & Little, 2018). Students with disabilities or other minority backgrounds are removed from their classrooms at higher rates than their peers (Losen & Gillespie, 2012; Office of Special Education Programs, 2020). Such punitive practices have been associated with negative outcomes for the most at-risk youth. Thus, educational stakeholders have begun to move away from these punitive practices toward more positive behavior management methods. This study sought to examine the impact …

Cover-Crop Effects On Near-Surface Soil Properties Over Time In The Lower Mississippi River Valley, Cooper Fanning

Graduate Theses and Dissertations

Human population growth and climate change are present stressors that continue to put pressure on current agricultural production systems, where typical row-crop agricultural practices can negatively impact soil health. Extensive use of cover crops (CC) to increase soil health remains widely unrealized. Soil health in Arkansas is a major concern for sustaining agricultural output, therefore research into CC implementation across Arkansas to maintain or improve soil health is needed. The objective of this study was to evaluate the effects of CC (i.e., with and without CC) across various physical, hydraulic, biological, and chemical soil indicators in the Lower Mississippi River …

Feasibility Study For The Application Of A Solar Powered Absorption Chilling System For Cooling Poultry Houses In Northwest Arkansas, Matthew James Kelly

Graduate Theses and Dissertations

This paper investigates the economic feasibility of utilizing a solar-powered absorption chiller to provide cooling for poultry houses in northwest Arkansas. An existing thermodynamic model of a poultry house was modified to account for cooling. A simulation was performed using actual weather data from Fayetteville, Arkansas for 26 flocks of broilers at four cooling capacities for the 2020, 2021, and 2022 calendar years. Based on the simulation, the savings from reduced electricity use for ventilation and the cost of the required absorption chiller and solar thermal array for an 8-house farm were calculated. While providing cooling was found to reduce …

Struvite Effects On Greenhouse Gas Emissions From Flood- And Furrow-Irrigated Rice In The Greenhouse, Chandler Arel

Graduate Theses and Dissertations

Over time, as the influences of climate-change and declining, mineable, global phosphorus (P) reserves begin to impact agricultural production systems, alternative fertilizer sources and management practices, such as struvite (MgNH₄PO₄ · 6H₂O) and furrow-irrigation, will be necessary to accommodate nutrient and water demands. The precipitation and use of struvite as a fertilizer-P source could reduce environmental damages caused by nutrient-rich wastewater streams, supplement domestic P supply, and improve the sustainability of flood-, and furrow-irrigated rice production by reducing greenhouse gas emissions. The study of struvite from both chemical and electrochemical precipitation processes is well documented, …

Neural Interactions In Bottom-Up Communication, Prashant Chama Raju

Graduate Theses and Dissertations

The visual system’s remarkable ability to process vast amounts of sensory information rapidly and accurately is fundamental to cognitive neuroscience. This study investigates a key aspect of this capability: the compartmentalization of information into feature-specific subspaces during bottom-up communication. My primary question was: does Canonical Correlation Analysis (CCA) reveal a subspace that encodes color and direction of moving dot stimuli? I found that the first canonical component (CC1) does an excellent job decoding the stimuli, despite being one-dimensional while the stimuli were drawn from a two-dimensional space (red-green and up-down plane). I demonstrate that motion features are processed within distinct …

Tuning Electronic Transport And Magnetic Properties Of Layered Magnetic Materials, Md Rafique Un Nabi

Graduate Theses and Dissertations

Two-dimensional magnetic materials (2DMMs) have gained significant interest due to their potential for novel physical phenomena and device applications. Mn_2-xZn_xSb, with its tunable magnetic properties and stable tetragonal layered structure, offers a rich platform for exploring these phenomena. The introduction of Zn into the Mn₂Sb lattice efficiently tunes magnetic and electronic properties, making it a compelling candidate for high-performance spintronic devices.

With this motivation, we synthesized Mn_2-xZn_xSb (0 ≤ x ≤ 1) single crystals using a flux method. Mn2Sb exhibits ferrimagnetic order below 550 K with antiparallel spins aligned along …

Controls On The Development Of Hummocky Topography On Debris-Covered Glaciers, Ryan M. Strickland

Graduate Theses and Dissertations

Rock debris covers many glaciers in Earth’s highest mountains and the debris impacts glacier response to changes in climate. Interactions between debris, drainage, glacier dynamics, and climate produce contrasts in melt rates that cause debris-covered glaciers to develop complex, hummocky topography. Contrasts in melt rate produce thousands of hills–hummocks–and depressions. Ponds and ice cliffs often form in the depressions. Although ponds and ice cliffs occupy only a small fraction of the surface, they account for nearly half of glacier melt. Understanding the processes that control the development of hummocky topography is key to predicting the evolution of debris-covered glaciers. In …

To Each Their Own: The Relationship Among Regret, Habits, And Academic Performance In College Students, Chandler Ann Findley

Graduate Theses and Dissertations

The extant literature on regret as motivation for behavior presents inconclusive results, collectively. While it has often been agreed that regret motivates reparative action, most studies from the past 14 years indicate that regret may motivate either detrimental actions or, more commonly, no action at all. There also appears to be no published research about college students’ academic regrets or how these regrets affect their classroom behaviors and performance. Therefore, this dissertation seeks to understand if college students regret their academic habits, what those habits are, and how their regrets and habits contribute to their academic performance over the course …

A Two-Part Validation Study Of The Sexual Minority Identity Emotion Scale, Henrietta Kadi Tettey-Tawiah

Graduate Theses and Dissertations

A number of existing studies indicate that there is some correlation between pride and shame and various behavioral health outcomes like anxiety, depression, and self-harm in the general population. Research also confirms that this relationship is true among sexual minorities as well. This study sets itself up to interrogate this assertion vis-à-vis sexual minority adolescents (SMAs). Consequently, confirmatory factor analysis (CFA) and differential item functioning (DIF) detection analysis were performed on the 35-item Sexual Minority Identity Emotion Scale (SMIES) for SMAs. A tree-based modeling technique, specifically conditional inference trees (CIT), was then employed to explore and make predictions about the …

Investigation Of Optically Pumped Gesn Quantum Well Lasers, Grey Steven Abernathy

Graduate Theses and Dissertations

Silicon photonic integrated circuits enable the capability of producing on-chip processing of photonic signals, including both emission and detection. Emission materials, however, have been limited for monolithic integration due to high processing temperatures, indirect bandgap materials, and material integration complications. The (Si)GeSn material system has recently attracted attention due to the bandgap transition from the Si and Ge, naturally indirect bandgap, to direct bandgap with sufficient Sn incorporation. Additionally, the low growth temperature (CMOS compatible; <400 >°C) of (Si)GeSn materials can enable the monolithic integration of the highly desired mid-infrared light emission on the Si Photonic platform. This dissertation first discusses …

A Grain Of Hope: Analysis Of The Economic Potential For An Association Of South East Asian Nations (Asean) Rice Futures Market, Richard Nyarko

Graduate Theses and Dissertations

The ASEAN (Association of Southeast Nations) region is the world's leading rice producer, yet the region lacks a dedicated rice futures market. In contrast other world grain markets are served by liquid futures contracts, which aid producers through price discovery and risk management. This glaring gap raises a critical question: Can an ASEAN rice futures market be established to unlock the potential economic benefits for the region's rice sector? By predicting ASEAN rice pricing features and analyzing the efficacy of hedging for regional rice market players, this study explores the viability of an ASEAN rice futures contract to service the …