Digital Commons Network^™

An Environmental Systems Engineering Framework For The United States Space Force: Multi-Objective Optimization Of Co2 Emissions And Biodiversity Trade-Offs, Julio Roberto Pinto Covelli

Theses and Dissertations

The increasing demand for sustainable defense operations has prompted the US Space Force to explore advanced strategies that reduce carbon emissions and preserve biodiversity across its installations. This dissertation proposes a scalable systems-engineering framework that quantitatively integrates CO₂ emissions modeling and ecological simulation at RAF Feltwell and RAF Lakenheath, two strategically signi?cant installations with notable ecological value. Using toolsincluding Python, MATLAB, ArcGIS, and InVEST, this research models emissions and habitat quality under various operational scenarios. The study incorporates engineering performance metrics, including emissions intensity, resilience indicators, and energy efficiency rates, to inform trade-off modeling for real-time mission and environmental decision-making. …

Predicting Diversity Gaps In Clinical Trials Using Digital Twin Modeling, Abigail Tubbs

Theses and Dissertations

Demographic underrepresentation in clinical trials continues to limit the external validity, equity, and generalizability of biomedical evidence. While regulatory reforms have increased the availability of aggregate demographic reporting, most existing approaches assess representation retrospectively, after recruitment has begun, offering limited support for design-stage decision-making. This dissertation presents a digital twin–based framework for prospective assessment of demographic diversity in clinical trials using trial-level metadata. The work integrates three core contributions. First, an open, reproducible, no-code extraction tool was developed to enable bulk retrieval and harmonization of baseline demographic data (race, ethnicity, sex/gender, and age) from ClinicalTrials.gov using National Clinical Trial identifiers. …

Enhancing Geothermal Productivity In The Red River Formation, Williston Basin: Utilization Of Unconventional Stimulation Technology And Sco2 Injection To Improve Geothermal Inlet Temperature, Fluid Flow Rate, And Project Economics, Etochukwu Jude Uzuegbu

Theses and Dissertations

Geothermal energy is a reliable renewable energy source capable of delivering consistent baseload electricity while emitting very low concentrations of greenhouse gases. In very low permeable geothermal reservoir, the geothermal system’s efficiency and economic feasibility are heavily dependent on reservoir productivity, which includes the fluid circulation and heat extraction efficiency. This research assesses the geothermal inlet temperature dynamics, fluid production and techno-economic viability of two reservoir productivity enhancement approaches: Hydraulic Fracturing (Base Case model) and Fishbones stimulation (Proposed Case model) under various operational conditions. The research aims to evaluate the influence of these two approaches on the geothermal inlet temperature, …

Techno-Economic Analysis And Density Functional Theory Modeling Of Hydrogen Fuel Cells With Platinum-Based Catalysts For Effective Deployment In Long-Range Electric Vehicles, Thomas Cheekwang Yap

Theses and Dissertations

The transition to sustainable transportation is constrained by carbon emissions and fossil fuel dependence. Hydrogen fuel cells (HFCs), particularly those utilizing platinum-based catalysts, offer high efficiency and suitability for long-range electric vehicles (EVs). However, the high cost and durability limitations of platinum catalysts remain major barriers to large-scale deployment.

This study integrates techno-economic analysis (TEA) with density functional theory (DFT) modeling to evaluate cost–performance trade-offs of platinum-based catalysts for long-range hydrogen fuel cell vehicles. DFT simulations were conducted to assess platinum alloy compositions and oxygen reduction reaction activity. These performance metrics were incorporated into a MATLAB-based TEA framework to quantify …

Decomposition And Spectral Characterization Of Unsteady Loads In Pulse-Jet Propulsion Testing, Cesar Benitez

Theses and Dissertations

Pulsed jet propulsion systems produce inherently unsteady forces whose time-resolved characterization is essential for performance assessment, yet the measured load signal conflates aerodynamic forcing with the dynamic response of the measurement balance itself. This thesis develops a load centered framework for the dynamic characterization of a pulsed jet system, treating the measured load fluctuation as the primary physical observable rather than attempting full true-thrust reconstruction. A single-degree-of-freedom balance model identified through ringdown testing provides the structural reference scale, yielding a natural frequency of 8.5 Hz and damping ratio of 18%. Power spectral density, phase-averaging, and synchronous–residual decomposition is applied uniformly …

Examining The Effects Of Lateral Loading On Railroad Tapered Roller Bearings, Abel David Sanchez Trinidad

Theses and Dissertations

The loading conditions experienced by freight railcar bearings vary as a function of vehicle operating conditions. Under static conditions, bearings are primarily subjected to radial loads transmitted through the wheelset. During operation, however, track irregularities, braking events, railcar load imbalances, and curving introduce complex impact, longitudinal, and lateral forces in addition to the normal radial loading. These lateral forces increase friction within the bearing raceways, which could accelerate wear and potentially lead to premature spall initiation and propagation. While prior research at the University Transportation Center for Railway Safety (UTCRS) has demonstrated that vibration signatures can be used to detect …

Electrical Resilience In Water Treatment Plants: An Extreme Weather And Lightning Protection Study, Genesis Martinez

Theses and Dissertations

Water treatment plants (WTPs) are vital infrastructure systems that depend on sensitive electrical, electronic, and control equipment to ensure the continuous supply of safe drinking water and effective wastewater treatment. As global temperatures rise and climate change accelerates, the frequency and intensity of extreme weather events—such as hurricanes, flooding, and increased lightning activity—are becoming more pronounced. These events pose significant risks to the electrical resilience of water treatment facilities, often leading to power outages, equipment failures, grid instability, and prolonged service disruptions. This report explores the impacts of extreme weather, with a particular focus on lightning and electrical surges, on …

Mechanistic Investigation Of Arsenic Removal From Drinking Water Using Metal–Organic Frameworks And Granular Activated Carbon, Mousa Almousa

Theses and Dissertations

Arsenic contamination in groundwater represents a critical environmental and public health challenge due to its high toxicity and widespread occurrence in natural aquifers. Chronic exposure to arsenic, even at trace levels, is associated with severe health effects, including skin lesions and increased cancer risk. Conventional treatment technologies, such as adsorption using activated carbon or metal oxides, often suffer from limited selectivity, regeneration difficulty, and reduced efficiency under varying pH conditions. Therefore, developing advanced sorbent materials with high capacity, selectivity, and structural stability is essential for addressing arsenic pollution in decentralized water systems.Metal–organic frameworks (MOFs) have recently emerged as promising materials …

Variable Selection Via Penalized Logistic Regression For Binary Classification, Gloria Antwi-Boasiako

Theses and Dissertations

In this study, we developed some hybrid estimators for variable selection in logistic regression by integrating the sparse local gradients (SLG) with some existing variable selection methods such as LASSO, Elastic net, SCAD, and MCP. The goal is to retain the flexibility of penalized likelihood estimation while improving the stability and interpretability of the selected model.

The finite-sample performance of the proposed methods is examined through a Monte Carlo simulation study covering low-, moderate-, and high-dimensional settings under different levels of predictor correlation. The simulation results show that incorporating SLG screening generally leads to more controlled model sizes and fewer …

Geochemical Modeling Of Co2 Sequestration In Saline Aquifer: Broom Creek Saline Aquifer, Lawrence Chima Asouzu

Theses and Dissertations

Geological carbon sequestration in deep saline aquifers is widely regarded as a critical technology for mitigating anthropogenic CO₂ emissions. This dissertation presents a formation-specific, kinetically constrained reactive transport modelling study of CO₂ storage performance in the Broom Creek Formation, a quartz- and feldspar-dominated saline aquifer in the Williston Basin, North Dakota.

A high-resolution geological model was constructed in Petrel using well logs, well tops, and Sorensen’s permeability correlation, then exported via RESCUE file into CMG GEM for dynamic reactive transport simulation. The base-case scenario involved injection of CO₂ at 15 MMScf/day for one year, followed by 199 years of post-injection …

Non-Terrestrial Colonial Security And Critical Contingency Operations, Augustine Gabriel Wesley Batten

Theses and Dissertations

Since the turn of the century, the dependence of state functionality and capability on cyber infrastructure has grown exponentially, resulting in an equally expanding list of means to exploit this dependency. Cyberattacks have demonstrated the ability to target the space industry and critical infrastructure beyond our atmosphere. The potential damage this growing threat can bring is what this research aims to prepare for and mitigate. The purpose of this research is to determine cyber-attack indicators and develop responses designed to mitigate the effects of worst-case scenarios. It is important to understand that this study included a theoretical scenario to address …

Studying The Hidden Heat: A Theoretical Approach To Better Understanding The Thermal Conditions Of The Yellowstone Volcano In Wyoming, Usa, Daniel Burke Brunson

Theses and Dissertations

Using the spatiotemporal record of the 2.1–0 Ma ignimbrite flare-up of the Yellowstone Plateau Volcanic Field (YPVF) as a proxy for batholith formation at depth, this dissertation develops and applies the Finite Difference Heat Flow Simulation (FDHFS) program to model crustal thermal evolution beneath the supervolcano. FDHFS, a modular C++ numerical simulator, solves the transient heat equation incorporating variable thermal conductivity, radiogenic heat production, and directional advection in three-dimensional Cartesian grids. Validation against analytical benchmarks and seafloor-spreading analogs confirms its fidelity for combined conduction-advection processes in heterogeneous crustal settings.

High-resolution volume–time analysis of major ignimbrite pulses (Huckleberry Ridge, Mesa Falls, …

Safety Assurance In A Collegiate Flight Program With Safety Management Systems (Sms): A Mixed-Methods Approach To Evaluating Safety Risk Control Effectiveness, Erin Dunker

Theses and Dissertations

This study examined safety assurance and the effectiveness of safety risk controls within a collegiate flight training program operating under a Safety Management System (SMS). Using a mixed-methods approach, the research integrated quantitative survey data with organizational safety performance data to evaluate how safety risk controls function across operational domains. A survey instrument, the Collegiate Aviation Safety Risk Control Effectiveness Scale (CASRICES), was developed and validated to measure perceptions of safety risk control effectiveness among respondents using Exploratory Factor Analysis (EFA), Reliability, and Construct Validity Analyses.

The EFA supported a three-factor structure consisting of Pilot Training Risk Controls, Safety Reporting …

Strengthening Teacher Retention Through Strategic Onboarding, Stacey Eger-Converse

Theses and Dissertations

The United States education system is currently facing a critical staffing crisis characterized by dwindling enrollment in teacher preparation programs and alarming rates of voluntary attrition. Each school year, school districts report difficulties filling certified positions. This cycle of departure incurs staggering fiscal costs and creates a "recursive loop" where high turnover leads to lower student performance and community dissatisfaction, which further drives teacher exits. While most new teachers participate in induction programs, districts continue to lose approximately half of their new hires, suggesting that current support structures are insufficient. This research addresses a significant gap in the literature: the …

Critical Minerals Recovery From Oil And Gas Fields Produced Water In The Bakken Formation, North Dakota, Md Jakaria

Theses and Dissertations

The growing demand for critical minerals essential to clean energy technologies presents an opportunity to transform oilfield produced water (PW) – traditionally treated as waste – into a valuable resource. This dissertation investigates the recovery potential of lithium, salts, and other critical elements from produced water in the Bakken Formation, North Dakota, and evaluates the economic feasibility of integrating such recovery processes into existing petroleum operations. Comprehensive geochemical analyses were conducted on samples collected throughout the Bakken, revealing total dissolved solids (TDS) ranging from 46,815 to 327,714 ppm and lithium concentrations exceeding 200 ppm in several wells, indicating economically recoverable …

Biomanufacturing Of Carbon-Based Fuel & Chemical Products And Beccus Solutions For De-Carbonization In Texas And The Gulf Coast, Darrell Mayon

Theses and Dissertations

This research investigates the integration of advanced biomanufacturing technologies and Bioenergy with Carbon Capture, Utilization, and Storage (BECCUS) systems to decarbonize fuel and chemical production in Texas and the Gulf Coast. The region, which leads the United States in petroleum refining, petrochemical manufacturing, and CO₂ transportation infrastructure, represents both a major source of greenhouse gas emissions and a strategic opportunity for large scale carbon mitigation. While bio-based chemicals such as bioisoprene are technically feasible and demonstrate significantly lower life cycle greenhouse gas intensities compared to fossil based counterparts, their commercial deployment remains constrained by economic and systemic barriers. The central …

Thriving Within Digital Learning Courses: Examining The Influence Of Interactions In Kinesiology Undergraduate Students, Jimmy J. Morin

Theses and Dissertations

The expansion of online and hybrid education has reshaped higher education, particularly in applied fields such as kinesiology that emphasize hands-on learning. Despite this growth, limited research has examined how specific interaction types (academic, social, and deeper life) contribute to student thriving in digital environments. This dissertation explored how interactions with faculty, staff, and peers influence holistic student success in online and hybrid kinesiology programs utilizing a three-paper dissertation approach to address this gap through complementary methods. Paper 1 synthesizes existing literature on student interactions and thriving in digital learning contexts. Paper 2 uses one-way ANOVA and ANCOVA to examine …

A Privacy-Preserving, Ai-Driven Framework For Bathroom Activity Monitoring And Health Recommendation In Elderly Care, Collins Poku Obeng

Theses and Dissertations

The rapid aging of the global population necessitates scalable, non-invasive solutions, for monitoring Activities of Daily Living (ADLs) to detect early signs of health decline. This thesis presents a novel, end-to-end framework for monitoring bathroom activities—specifically bathing, toileting, and oral hygiene—using wearable sensors, machine learning and Agentic Artificial Intelligence (AI). The research addresses three critical gaps: the lack of granular activity recognition in privacy-sensitive spaces, the need for personalized health insights without manual logging, and the cybersecurity risks inherent in deploying AI in healthcare. First, algorithms utilizing wearable humidity and accelerometer sensor data were developed to classify hygiene behaviors with …

Numerical Investigation Of Plume–Surface Interactions Using Automated Adaptive Mesh Refinement, Fahim Shahriyar

Theses and Dissertations

This work presents a numerical investigation of plume–surface interactionsusing the Direct Simulation Monte Carlo (DSMC) method, coupled with the devel opment of an automated adaptive mesh refinement (AMR) framework for rarefied flow simulations. A two-dimensional axisymmetric configuration is used to simulate the impingement of a rarefied exhaust plume on a flat surface under vacuum condi tions representative of experimental test facilities. Surface pressure, shear stress, and heat flux induced by plume impingement are computed and compared with published experimental and numerical results to validate the DSMC approach. To address the strong mesh sensitivity and computational inefficiency associ ated with uniform …

Reducing Structural Barriers In Teacher Preparation: An Improvement Science Study Of A Year-Long Residency Model In Rural Nevada, Brian Zeiszler

Theses and Dissertations

Teacher shortages in Nevada, particularly in rural school districts, have been exacerbated by structural barriers within teacher preparation programs that limit candidate progression to graduation and licensure. This study examines the Teacher Education Program (TEP) at Great Basin College (GBC) as a case to identify these barriers and evaluate the implementation of a year-long teacher residency model as a strategy for improvement. Guided by institutional theory, situated learning theory, and constructivism, this study conceptualizes candidate challenges as systemic rather than individual, focusing on how program structures influence access, persistence, and readiness for licensure.Using a qualitative-dominant mixed-methods case study design, Artifact …

Moodify: A Mood-Based Music Recommendation System, Meghana Kagitha

Theses and Dissertations

Music has long been recognised as a powerful tool for emotional regulation, yet existing music streaming platforms often fail to align song recommendations with a user's current emotional state. Moodify is a mood-based music recommendation system designed to bridge this gap by delivering personalised playlists that reflect how a user feels in real time.

This project presents the design, development, and evaluation of Moodify, a mobile application that leverages the Circumplex Model of Emotion to capture user mood through an intuitive two-dimensional valence-arousal interface. Rather than relying on text input or manual search, users plot their emotional state directly onto …

Adaptive Artificial Potential Field Guidance And Control For Autonomous Docking With Uncooperative And Unknown Spacecraft, Steven Holmberg

Theses and Dissertations

The increasing demand for on-orbit servicing (OOS), active debris removal (ADR), and space domain awareness (SDA) missions has increased the need for autonomous spacecraft rendezvous and proximity operations (RPO) with uncooperative and unknown targets. Traditional guidance and control methods are typically designed for cooperative systems with known geometry and state information. This work builds on previous research to develop and evaluate an artificial potential field (APF)-based control framework capable of autonomous operation with minimal prior target knowledge and applicability to both relatively static and tumbling spacecraft.

The proposed APF formulation incorporates established safety constructs from cooperative docking systems, including an …

Low-Vision Students’ Experiences With And Suggestions To Improve Desktop Virtual Reality: A Qualitative Study, Tanveer Mansur Syed

Theses and Dissertations

Visually impaired students have faced challenges in the field of education, particularly in science education. Not surprisingly, the unemployment rate for working-age visually impaired people has been above 70%. This persists despite federal laws to support the education and employment of visually impaired people,

Virtual Reality (VR) technology has evolved for several decades. Its use has proliferated in areas that include education. Today, VR science lab simulations are presented as a cost-effective alternative to traditional science labs. Research shows these to be viable substitutes to traditional science labs without a significant drop in learning outcomes. However, this researcher was unable …

An Experimental Study On Turbine-Based Energy Harvesters For Thermal Underwater Gliders, Stephen Edward Coster

Theses and Dissertations

Buoyancy-driven underwater gliders have been optimized for long-duration missions primarily for continual monitoring of the ocean’s water column. However, longer missions and higher-powered sensors have increased the energy requirements of gliders. While current solutions aim to increase battery capacity, the development of energy-harvesting systems (EHMs) could greatly improve mission capabilities in both ability and duration. This thesis discusses the experimental testing of an underwater glider with an EHM as detailed in the theoretical study, “Development of a Turbine-Based Ocean Thermal Energy Harvesting Mechanism Applied to the Underwater Glider” by Hongbo Hou, PhD. The rear-mounted turbine captures energy using the kinetic …

Degradation And Metabolic Analysis Of Synthesized Quorum-Sensing Signals By The Model Eukaryote Chlamydomonas Reinhardtii, Adam Josef Bach

Theses and Dissertations

Bacterial organisms can “talk” with one another on a colony-wide scale using a communication system known as quorum-sensing (QS) via chemical signals. These signals are produced at a basal rate throughout the life of the bacteria and are classified as autoinducers, which diffuse across the cell membrane. Once the critical concentration is reached, they begin to diffuse back into the cell and initiate a phenotypic change. As these signals exist outside the membrane of their producer, they are also accessible to other organisms. It has already been noted that some plant species uptake these compounds through their roots and break …

A New Approach To Generate Combinatorial Patterns In Logical Analysis Of Data And Its Application To Predict College Retention, Salihah Ahmed E. Jaafari

Theses and Dissertations

Student retention and degree completion remain central challenges for higher-education institutions, with significant implications for student success, institutional effectiveness, and public accountability. While advances in predictive analytics have enabled earlier identification of students at risk of withdrawal, many commonly used machine learning approaches suffer from limited interpretability, constraining their practical usefulness for advising, intervention, and policy decision making. This dissertation addresses the problem of predicting student persistence by developing and evaluating optimization based, interpretable classification models within the Logical Analysis of Data (LAD) framework. Building on existing LAD formulations, this research introduces two novel pattern generation models, the Best Term …

Range Extension Of Electric Propulsion General Aviation Aircraft Using Solar Technology, Mary Kathryn Shultz

Theses and Dissertations

Alternative propulsion technologies in aviation have been a long-time topic of interest as operators aim to bypass growing fuel prices and meet environmental sustainability requirements set globally. Research regarding alternative propulsion technologies is primarily centered around marginally improving efficiency of combustion systems or large-scale implementation of novel technologies. This research evaluates the feasibility of implementing solar-integrated propulsion for general aviation aircraft to extend range through a comparison of full-electric, hybrid solar, and internal combustion engine propulsion systems. This evaluation of existing technology by range analysis indicates that hybrid solar‑electric propulsion is viable primarily for short‑range training and recreational aircraft, rather …

Aircraft Fault Detection Via Weight And Bias Analysis Of A Custom First Neural Network Layer, George Harrison Chen

Theses and Dissertations

Fault detection in aircraft is traditionally handled through redundant hardware and comparison algorithms to detect failures. Alternatives like model-based residual generation and data-driven approaches such as supervised fault classification and unsupervised anomaly detection have been explored, but they suffer from practical limitations; model-based methods require accurate system models, and data-driven methods have large constraints on the data limiting scalability and adaptability. This work presents a purely data-driven neural network architecture featuring a custom first layer designed for real-time fault detection where the weights and biases of this layer are used to detect faults. The network requires zero supervision and complements …

Manned Exploration Of Satellites Of The Outer Planets: An Analysis Of Current Technologies And A Discussion Of Advancements Required, Joshua Carson Meador

Theses and Dissertations

The Solar System’s outer planets have many satellites, some of which are known to be the most likely places to find extraterrestrial life in our celestial backyard. Multiple scientific missions have been sent to glean information from these satellites, yet the possibility of a manned expedition has long been exclusive to science fiction stories. This paper intends to collect and analyze the current state of space travel technology to explore the feasibility of such a mission with modern technology and to discuss which future advancements should be the focal point for making such missions a reality. To begin, data on …

Hdra-Fusion: Hybrid Detection With Routed Architecture For Manipulation-Aware Ai Face Forgery Detection, Omar Ebeid

Theses and Dissertations

With the rapid advancements in artificial intelligence-based image generation and manipulation tools, it is extremely difficult to detect if an image is genuine or artificially crafted. Despite extensive research in this area, existing image detection systems suffer from three major problems: suboptimal cross-dataset generalization due to shortcut learning of dataset-specific patterns, unreliable probability estimates due to domain shift, particularly in cross-manipulation evaluation settings, and an inability to detect images manipulated by multiple types of manipulations within a single detection framework. To address these limitations, we propose HDRA-Fusion (Hybrid Detection with Routed Architecture), a framework built on the conclusion that different …