Digital Commons Network^™

A Theoretical Investigation Of Photo-Induced Deformations And Transitions In Nanoscale Ferroelectrics, Carmel Dansou

Graduate Theses and Dissertations

This dissertation presents a comprehensive first-principles investigation into the interaction of light with ferroelectric materials, focusing on light-induced structural responses (photostriction) and phase transitions in Ferroelectric superlattices, epitaxially strained BiFeO3 thin films, and twodimensional NbOX2 (X = Cl, Br, I) ferroelectrics. The work aims to provide microscopic insights into how light can control the lattice structure and even the crystallographic phase in these systems, with the broader goal of informing the design of light-responsive functional materials for practical technological applications. The first part explores light-induced effects in PbTiO3/SrTiO3 superlattices with different polarization orientations. Our simulations reveal that photoexcitation modifies the …

A Mobility Data-Driven Approach To Analyzing And Modeling Park Accessibility Inequities And Use In U.S. Cities, Michaelmary Chukwu

Graduate Theses and Dissertations

Urban Park accessibility inequities have been a longstanding issue globally and the United States in particular. Despite the benefits that urban parks provide, use and access is not equitably distributed among the population, often favoring historically privileged populations over others (disadvantaged). Fortunately, improvements have been made in recent years to promote balanced park distribution in some cities; however, evidence still shows that most cities are behind. Interestingly, the rise in human mobility data has facilitated the study of human behavior and use of activity spaces. This thesis advances the existing studies on park accessibility and emerging human mobility to study …

Switching Performance Optimization Of Sic Mosfets With Digital Active Gate Drivers, Liyang Du

Graduate Theses and Dissertations

Silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) have extensive applications in high-power density devices, but they exhibit quick switching transients that are problematic, including electromagnetic interference (EMI), voltage overshoot, and current imbalance between paralleled devices. The purpose of this dissertation is to maximize the switching performance of SiC MOSFETs using digital active gate drivers (AGDs). A three-level gate driving approach is presented to improve current sharing in paralleled SiC MOSFETs through turn-on voltage and gate signal delay adjustment. Closed-loop control with real-time feedback ensures high-reliability operation. For better practicability, a compact AGD structure of a single-path Class-B amplifier-based topology is …

Urbanization, Climate Change, And Water Quality In Northwest Arkansas Caves, Eliezer Ugarte

Graduate Theses and Dissertations

The Ozark Cavefish is one of multiple species of conservation concern found in Cave Springs Cave and Logan Cave in Northwest Arkansas (NWA). Over the past two decades, the urbanization of NWA has negatively impacted the recharge areas of both caves, and in turn the water quality of both cave streams. The changing climate has also altered temperature and precipitation, which influence many aspects of karst groundwater. These effects are shown in the historical water quality records for both caves. However, these records are from varied sources and have never been comprehensively compiled and analyzed. This thesis approaches the issue …

Exploring The Relationship Between Grit, Burnout, And Academic Success Among First-Year Osteopathic Medical Students During Fundamentals Of Anatomic Science I Course, Heather Guzik

Graduate Theses and Dissertations

Burnout is a significant issue among healthcare professionals. Burnout refers to the mental, emotional, and physical exhaustion that can develop throughout one’s career or studies. It can affect professionalism and patient care (National Academies of Sciences, Engineering, and Medicine: National Academy of Medicine, 2019). Studies have shown that burnout begins early in an individual's medical education and can increase throughout their training (Voltmer et al., 2021). It has been suggested that students with a high level of Grit may exhibit some resistance to burnout (Jumat et al., 2020; Lee et al., 2022). This noncognitive trait measures a person’s ability to …

Nanoparticle Iron Based Catalysts For Clean Water And Other Applications, Shelby Lynn Foster

Graduate Theses and Dissertations

This dissertation explores the development, characterization, and application of iron-based catalysts for environmental remediation and energy generation. The research focuses on Fe-based nanomaterials for water purification, electrochemical ammonia production, and ethanol oxidation enhancement. The first section of the dissertation investigates the removal of water contaminants using nickel-iron (NiFe) bimetallic nanoparticles. Various NiFe ratios were synthesized and tested for their efficiency in degrading the azo dye (Orange G), with lower Ni content formulations achieving 80–99% dye removal within 60 minutes. Results show that changing the molar ratio of nickel to iron caused different removal rates, as well as the extent of …

Photochemical And Electrochemical Assessment Of Uio-66-Nh₂/G-C₃N₄ Thin-Film Heterostructures As Potential Candidates For Hydrogen Evolution: An Experimental Study Augmented By Dft Insights, Nour Abou Seada, Maryam Glal Elmahgary, Sameh O Abdellatif, Khalid Kira

Biochemical Engineering

The global shift towards carbon-neutral energy systems has catalyzed an intensified focus on sustainable hydrogen production, with photo and electrochemical water splitting emerging as a particularly promising pathway. This study elucidates the design, simulation, and synthesis of advanced photo and electrocatalytic materials tailored for the hydrogen evolution reaction (HER), concentrating on heterostructures formed by zirconium-based metal-organic frameworks (MOFs)—specifically, UiO-66 and its amine-functionalized derivative, UiO-66-NH₂—in conjunction with graphitic carbon nitride (g-C₃N₄). Employing density functional theory (DFT) simulations, we pre-screened the electronic properties of the MOFs, revealing that amine functionalization significantly narrows the bandgap and optimizes band alignment, thereby enhancing photocatalytic activity. …

From Imaging To Impact: A Multi-Disciplinary T32 Program Framework And Initial Insights For Training In Image-Guided Cancer Therapy, Kari J Brewer Savannah, Stephen Y Lai, Clifton D Fuller, Kristy K Brock

Faculty, Staff and Student Publications

As multi-disciplinary image-guided assessment and therapies become increasingly important for precision oncology, the need for comprehensive training opportunities that effectively prepare the next generation of clinician-scientists and scientists is evident. We present an innovative, evidence-based research training framework that integrates the following critical features: 1) intentional and personalized mentoring and career development, 2) immersive research in image-guided cancer therapy, 3) strategic mentored clinical exposure, 4) structured didactic learning and professional development opportunities, and 5) mentored grant writing. Designed to foster scientific rigor, translational thinking, and multi-disciplinary collaboration, the Image-Guided Cancer Therapy T32 Training Program (IGCT-T32) aims to prepare postdoctoral fellows …

Career Advising Utilization: A Quantitative Archival Analysis Of Student Engagement Across Academic Levels And Colleges At A Southeast University, Edward Raimundi Iii

Electronic Theses and Dissertations

This quantitative ex-post facto study examined patterns of career advising utilization at a large, R1 public university in the southeastern region of the United States. Institutional advising data from the 2023–24 advising year was utilized to identify usage patterns across different demographics such as college affiliation and academic level. The descriptive stats from the archival data were used to measure topic distributions, undergraduate–graduate usage by college, and contact engagement. The sample size included over 35,000 students with 10 different college affiliation labels. Significant differences across advising usage in the different colleges were found during the study. Undergraduate students had higher …

Differences In Peer Social Connections Between Traditional And Online Nurse Residency Programs, Tatum Leonard

Electronic Theses and Dissertations

The anticipated retirement of baby boomer nurses by 2030 will intensify the global nursing shortage, a crisis that demands innovative strategies for onboarding and retaining new graduate nurses. Nurse residency programs (NRPs) are designed to ease the transition from student to practicing nurse, reduce turnover, and foster professional resilience. Amid the COVID-19 pandemic, many NRPs rapidly transitioned from traditional, in-person seminars to synchronous, online formats. This study explored differences in peer social connections between traditional and online NRPs, focusing on three constructs: sense of community, collaborative learning, and peer social support. Using a quasi-experimental, mixed methods approach, this secondary data …

Underrepresentation Of African American Women Superintendents In The Public Schools Of Texas: Descriptions Of Their Lived Experiences, Shani R. Wyllie

Electronic Theses and Dissertations

The problem addressed through this study was the underrepresentation of African American women superintendents in the public-school districts of Texas, despite women making up a majority of the public-school workforce. The purpose of this transcendental phenomenological study was to describe the lived experiences of African American women superintendents regarding the support and barriers they encountered as they navigated their journeys to the position of public school district superintendent in Texas. The study was grounded in the Black feminist thought framework. Five semistructured interviews were conducted with currently serving African American women superintendents in Texas. The participants had been in the …

Electrical Characterization Of Germanium Tin Alloys And Devices For Space Reliability, Kevin K. Choe

Theses and Dissertations

GeSn (germanium tin) alloys are potentially well suited for near-mid infrared space optoelectronic applications. Alloys of GeSn have similar properties to group III-V and mercury-cadmium-telluride semiconductors and are compatible with cost-effective complementary metal oxide semiconductor (CMOS) manufacturing technology. Recent progress in non-equilibrium remote plasma-enhanced chemical vapor deposition (RPECVD) has enabled the crystalline growth of GeSn with Sn concentrations of up to 10% without Sn surface segregation. Several experimental studies in previous literature report CVD- or molecular beam epitaxy (MBE)-grown GeSn alloys achieving a direct bandgap with 6%-9% Sn content. This novel growth technique opens opportunities for a cost-effective, next-generation optical …

Nuclear Structure Of Neutron-Deficient Cesium-126 And Cesium-127, Connor M. Gautam

Theses and Dissertations

Lifetimes of seven excited states of ¹²⁷Cs, including the states populating the isomer, were measured through a combination of spectroscopic methods. The spin and parity of the states leading up to the 171-μs isomeric level of ¹²⁶Cs were assigned for the first time, new values were measured for the lifetimes of the two isomeric states, and new evidence was presented for the assignment of a detached sequence of gamma rays to the ¹²⁶Cs nucleus.

Automation Of Lcmc Logistics Processes: A Delphi Approach, Kline M. Alt

Theses and Dissertations

As the U.S. Air Force confronts growing complexity in system acquisition, the implementation of digital models in system design and logistics process management allows the incorporation of digital tools and the possibility for automation of portions of logistics processes. This thesis investigates where these technologies can be most effectively integrated within the Air Force Life Cycle Management Center logistics enterprise (AFLCMC). Using a three round Delphi study, AFLCMC logistics subject matter expert (SME) opinions were solicited from program-level senior logisticians, program managers to identify high-need areas, key success factors, and potential barriers to adoption. Quantitative consensus from Likert-scale and ordinal …

Investigating The Impact Of Forest Vegetation On Nuclear Weapon Prompt Radiation Energy Deposition, Paul A. Clement

Theses and Dissertations

This work seeks to answer the unstudied questions “Does a layer of vegetation impact the prompt radiation energy deposition in the soil from an atmospheric nuclear detonation?” and “If yes, by how much?” A new methodology was developed to repeatably automate and streamline a process of generating a three-dimensional geometry for subsequent radiation transport simulations and statistical analysis. The methodology streamlined three diverse applications: a three-dimensional mesh generator, a radiation transport simulation code, and a sensitivity analysis & uncertainty quantification software. The methodology was tested by simulating the quantitative influence that vegetation has on changing the energy deposition into the …

Tensile Creep Of A Hybrid Polymer-Matrix/Ceramic-Matrix Composite At Elevated Temperature, Waleed S. Alshehri

Theses and Dissertations

Advanced aerospace systems require structural materials that can perform reliably in high-temperature environments for long durations. The performance of standard polymer matrix composites (PMCs) in these conditions is often limited by their susceptibility to time-dependent deformation, such as creep. The objective of this research is to characterize the high-temperature creep behavior of a novel unitized material system comprising a polymer matrix composite (PMC) and a ceramic matrix composite (CMC) co-cured together. The PMC part consists of the polyimide matrix reinforced with laminated carbon fibers woven in an eight harness satin weave (8HSW). The CMC part consists of a zirconia-based ceramic …

Low-Cost Transfers For Cislunar Liaison Navigation, Ka'eo J. Swartzmiller

Theses and Dissertations

CubeSats have an inherent limitation on volume due to their small form factor. Naturally, this extends to the capacity of on-board ΔV, thus limiting the maneuverability of the satellites. This limited maneuverability makes it extremely important to be intentional when planning out mission trajectories. The cislunar region subjects these trajectories to the gravitational forces of both the Earth and the Moon, making it all the more necessary to deliberately plan out maneuvers. The Circular Restricted Three Body Problem (CR3BP) provides a simpler model for estimating the motion of spacecraft within the cislunar region, allowing for the gravitational forces to be …

Multi-Fidelity Machine Learning Modeling For Aerodynamic Response Prediction Of Aerospace Vehicles, Ethan S. Jackman

Theses and Dissertations

Hypersonic vehicle design requires understanding complex aerodynamic phenomena across the full flight regime. This study presents a novel MF surrogate modeling methodology that enables the prediction the full field response across a vehicle’s surface. A Space-Filling Curve (SFC) is used to convert unstructured data into 1D vectors. The a Convolutional Autoencoder is used with transfer learning to reduce the dimensionality of the data. An Emulator-Embedded Neural Network (E2NN) combines multi-fidelity data for fast, accurate predictions. A benchmark analytical example and hypersonic application are used to evaluate the methodology. Using various numbers of samples and sampling strategies it is found that …

Designing An Experiment To Create And Evaluate Behavioral Changes In Air Force Pilots' Fuel Efficiency, Jackson Macias

Theses and Dissertations

Fuel represents over 70% of the logistical resupply demand within the Department of Defense, with the United States Air Force accounting for most of that consumption. While prior fuel efficiency efforts have primarily focused on technical upgrades, this research explores how behavioral interventions can influence pilot decision-making and operational energy outcomes. Using the Theory of Planned Behavior (TPB) as a guiding framework, this study investigates the effects of targeted behavioral strategies on pilots’ attitudes, subjective norms, perceived behavioral control, intentions, and actual fuel-efficient behaviors. A quasi-experimental design was applied through a controlled pilot study using simulator flights. Six participants were …

Designing The Protocol For An Experimental Flight Simulation Study Encouraging Fuel Efficient Behavior, Thomas S. Reardon

Theses and Dissertations

This study designed and tested an experimental instrument to examine how pilots respond to fuel efficiency feedback in a flight simulator. A standardized flight plan, script, and hardware setup were created using X-Plane 12 software and physical flight simulator hardware. The chosen sortie guided participants from Monterey Regional Airport to Moffett Federal Airfield using instrument flight rules (IFR). The flight script provided step-by-step guidance to ensure consistent behavior across participants. The simulator was mapped to match real cockpit controls and allowed for precise data collection including flight time, altitude, heading, and fuel use. The goal was to support a larger …

Implementing Lean Principles To Enhance Warehouse Operations At King Abdulaziz Air Base(Kaab): A Case Study Of Royal Saudi Air Force (Rsaf), Saleh A. Alghamdi

Theses and Dissertations

The Royal Saudi Air Force (RSAF) relies on efficient logistics to sustain readiness. At King Abdulaziz Air Base, warehouse receiving inefficiencies caused delays and waste. This study used Lean principles and a six-month time–motion analysis, with Pareto and Fishbone tools, to identify 55% waste in dead pile and 75% in palletized shipments. Standard times of 5.98 and 6.55 minutes were set. Key recommendations include SOPs, cross-training, forklift certification, layout redesign, and RFID. Lean adoption could save 100+ labor hours and $4,000 annually, improving safety, accuracy, and mission readiness.

Effect Of Workplace Design On Collaboration And Satisfaction In Space System Command, Joshua A. Hagood

Theses and Dissertations

This study addresses a significant knowledge gap regarding the influence of physical workplace design on employee collaboration and satisfaction with the physical environment within U.S. Space Force technical military organizations.  While seminal industry research consistently demonstrates that physical design and indoor environmental quality influence employee satisfaction and collaboration (e.g., Candido et al., 2015; Sailer et al., 2021), the understanding of these impacts within military contexts remains limited.  Using a quantitative post-occupancy evaluation survey, adapted from the Sustainable Post Occupancy Evaluation Survey (SPOES), multiple regression analyses revealed that physical elements collectively predict both satisfaction and collaboration.  The final simplified model showed …

Trends And Predictive Modeling Of Real Estate Prices In Major Saudi Arabia Cities, Meshal S. Aldahas

Theses and Dissertations

his research examines historical trends and explanatory modeling of real estate prices in major Saudi cities, with a focus on Riyadh, Jeddah, and Dammam. Using a mixed-methods approach, the study integrates quantitative data from 2010–2023, including housing and macroeconomic indicators, with qualitative insights drawn from over 320 survey responses that captured consumer sentiment on affordability, job security, and housing policies. A combination of descriptive statistics, ARIMA and Exponential Smoothing techniques was applied to detect long-term patterns, seasonal variations, and market shocks. Predictive modeling was conducted using Linear Regression, Decision Trees, and Neural Networks, with results showing that job security consistently …

A Review Of The United States' Long Term War Support Capabilities In The Indo-Pacific Command Region, Brian J. Mullin Jr.

Theses and Dissertations

This study examines U.S. maritime transportation readiness in the Indo-Pacific, highlighting fleet age, mariner shortages, shipyard decline, and port vulnerabilities. It also considers contested logistics and technological threats. Recommendations include fleet recapitalization, mariner pipeline growth, port diversification, and defensive upgrades. The study concludes that secure sea line assumptions are outdated and calls for greater resilience, with follow-on efficiency analysis proposed for ports and ships.

Spin State Of Positronium In Two Dimensions, Emille Bryant

Theses and Dissertations

We investigate the spin state of the electron-positron system positronium to determine experimental criteria that can identify a positronium anyon. Anyons have been posited to be the basis for a truly fault-tolerant quantum computer, but they have not been indisputably observed in experimental systems. Through the analysis of the fully relativistic symmetry group of fermions and bosons in three dimensions, we investigate the symmetry of its subgroups to determine that positronium in two dimensions behaves as a scalar with respect to rotations. We conclude that positronium in two dimensions has an arbitrary relative spin orientation of annihilation photons and only …

Computational Analysis Of Dna Methylation From Long-Read Sequencing, Yilei Fu, Winston Timp, Fritz J Sedlazeck

Faculty, Staff and Students Publications

DNA methylation is a critical epigenetic mechanism in numerous biological processes, including gene regulation, development, ageing and the onset of various diseases such as cancer. Studies of methylation are increasingly using single-molecule long-read sequencing technologies to simultaneously measure epigenetic states such as DNA methylation with genomic variation. These long-read data sets have spurred the continuous development of advanced computational methods to gain insights into the roles of methylation in regulating chromatin structure and gene regulation. In this Review, we discuss the computational methods for calling methylation signals, contrasting methylation between samples, analysing cell-type diversity and gaining additional genomic insights, and …

Supporting Employed Informal Caregivers, Michele Dinman, Natalie Galucia, Cal J. Halvorsen

Harvey A. Friedman Center for Aging

More than 53 million Americans are informal caregivers. These family members, friends, and acquaintances provide social, medical, transportation, and other support to individuals because of illness or disability without getting paid. Additionally, at least 2 million grandparents, not counting other kinship caregivers, provide care for children who cannot remain with their parents.1

Improving Hospital 30-Day Readmission Rates Through Post-Discharge Follow-Up Phone Calls, Maureen R. Wright

DNP and Student Works

Background: Thirty-day hospital readmissions compromise patient safety, increase mortality risk, and impose financial penalties on hospitals. Ineffective discharge education and care transitions leave patients vulnerable after discharge. Evidence shows that post-discharge follow-up calls within 24–72 hours can identify risks early and reduce preventable readmissions.

Purpose: This Doctor of Nursing Practice (DNP) project aimed to reduce 30-day hospital readmission rates by implementing post-discharge follow-up telephone calls guided by the Agency for Healthcare Research and Quality (AHRQ) Re-Engineered Discharge (RED) Toolkit.

Methods: Registered nurses conducted structured follow-up calls within 24–72 hours of discharge from the medical-surgical unit, reviewing health status, medications, appointments, …

Robust Ai Solutions For Financial Markets Through Generative Modeling, Dynamic Graph Learning, And Reinforcement-Based Portfolio Optimization, Jingyi Gu

Dissertations

Financial markets are inherently uncertain and dynamic, driven by complex factors such as macroeconomic signals, investor sentiment, and evolving inter-asset relationships. While machine learning has advanced financial modeling, existing approaches often fall short in addressing the real-world intricacies of finance. This dissertation confronts two critical challenges, human-driven stochasticity and risk-intensive decision-making under real-world trading constraints, while seizing a pivotal opportunity, the structural dynamics of evolving financial systems. These elements are foundational to advancing robust and practical financial intelligence.

To this end, this dissertation develops a unified framework for robust financial modeling and decision-making. The framework is architected as a progressive, …

Large-Scale Graph Algorithms And Applications With An Emphasis On Fintech Data, Fuhuan Li

Dissertations

Graph algorithms are essential analytical tools with applications spanning cybersecurity, biology, social media, and increasingly, financial technology (FinTech). The complex and interconnected nature of financial data, particularly in cryptocurrency networks, presents unique opportunities for graph-based analysis in fraud detection and anomaly identification.

This dissertation presents the design and implementation of scalable graph algorithms tailored for large-scale networks, with particular emphasis on FinTech applications. The primary contributions include: (1) novel cover-edge based triangle counting algorithms that significantly reduce computational overhead through breadth-first search preprocessing, achieving substantial speedups over traditional methods and dramatic communication reduction in distributed settings, (2) optimized parallel implementations …