Digital Commons Network^™

Evaluation Of Two-Group Iate Coupling With Pbe For Beyond Bubbly Flows In A Large Diameter Pipe, Sungje Hong, Joshua P. Schlegel, Subash L. Sharma

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

This study evaluates the two-group interfacial area transport equation (2G IATE) coupled with the S-Gamma (Sγ) population balance equation (PBE) model for beyond bubbly flow regimes in a vertical large-diameter pipe. The 2G IATE framework incorporates intergroup mass transfer mechanisms and is implemented within the Sγ model, which assumes a log-normal bubble size distribution. The numerical approach is validated against experimental data from Schlegel et al. (2012), with a focus on the void fraction and interfacial area concentration (IAC) distributions. The results show that 2G IATE improves the predictions of the void fraction and IAC, although its accuracy varies with …

Impact Of Bubble-Induced Turbulence On Two-Phase Flow Dynamics At High Void Fraction In A Large Diameter Channel, Sungje Hong, Joshua P. Schlegel, Subash L. Sharma

Nuclear Engineering and Radiation Science Faculty Research & Creative Works

This study represents the first investigation into the influence of bubble-induced turbulence (BIT) on interfacial area transport mechanisms in gas–liquid two-phase flows under conditions of high void fraction and high velocity in a large diameter channel. Given the unique characteristics of bubble flow in larger channels, the turbulent effects induced by bubbles differ from those observed in smaller channels. However, limited research exists regarding the impact of BIT beyond bubbly flows in large-diameter channels. To address this gap, two approaches for implementing the BIT model are explored: a direct method and an indirect method. This paper assesses both the general …

Autonomous Navigation Development And On-Ground Validation For Satellite Rendezvous And Proximity Operations, Logan Banker

Masters Theses

Spacecraft rendezvous and docking are critical mission phases for various applications of spaceflight, including active debris removal (ADR) and in-orbit servicing, assembly, and manufacturing (ISAM). While previous missions utilized humans to perform rendezvous and docking, this style of mission greatly increases safety risks and cannot be implemented on a large scale. Autonomous servicing satellites provide a path towards scalable rendezvous and proximity operations (RPO) because these autonomous agents do not require human intervention. This work presents a lightweight convolutional neural network (CNN) for the navigation system of an agent which analyzes monocular images and predicts the target's position and orientation …

Wattage- And Composition-Dependent Ocular Surface Toxicity: An In Vitro Study On E-Cigarette Aerosol Exposure In Human Corneal Epithelial Cells, Tzu-Ling Lin

Masters Theses

As electronic cigarette consumption continues to escalate globally, its impact on non-respiratory mucosal surfaces, particularly the ocular surface, remains largely understudied. This study investigated the toxicological effects of e-cigarette aerosols using a human corneal epithelial cell (HCE-2) model. Our findings reveal that aerosol exposure induces a significant, dose-dependent reduction in cell viability, exacerbated by higher device wattage and specific flavor agents such as watermelon. Exposure was found to trigger intracellular oxidative stress and the activation of apoptotic pathways, leading to programmed cell death. Furthermore, the upregulation of proinflammatory cytokines suggests that vaping may predispose users to chronic inflammatory conditions of …

Developing Discharge Estimation Algorithm Using Low-Cost Velocity Sensor And Machine Learning, Barkha Gautam

Masters Theses

Accurate river discharge estimation is essential for flood forecasting, water resources management, and hydraulic decision-making; however, continuous discharge records are unavailable at many river locations. Traditional stage-discharge rating curves are widely used but their reliability may decrease when channel conditions change or flow conditions vary rapidly. This study develops and evaluates Long Short-Term Memory (LSTM) models for discharge prediction using 15-minute time-series data from river monitoring stations in Missouri. Two model configurations, a baseline stage-only model and an enhanced stage-plus-velocity model, are developed and evaluated independently at two river sites to determine whether the inclusion of surface velocity improves discharge …

Examination Of Laser Microwelding As A Technique For The Repair Of Steel Castings, Allan John Woldow

Masters Theses

"Metal castings have long been plagued with minor defects caused by various process and design conditions. Commonly, minor defects are not seen until after machining operations have been completed, and by the time they are identified, they cannot be salvaged in a manner that is structurally sound and does not have other detrimental effects on the product. Detrimental effects may include warping from high heat input in traditional welding, warping from reheat treatment, oxidation of machined surfaces, microstructural anomalies, and reduced mechanical properties. Micro laser welding has the potential to provide a solution to these issues by providing a low …

Aura-Visionpose: Creating Datasets For Vision-Based Pose Estimation, Mohanad Alameer

Masters Theses

"Spacecraft rendezvous is an integral part of many orbital missions, including active space debris removal (ADR) and in-orbit servicing, assembly, and manufacturing (ISAM). Traditionally, rendezvous missions rely mainly on manual ground-based control to perform rendezvous and docking. While this can be effective on an individual basis, it becomes less practical at scale. Autonomous vision-based methods can reduce reliance on human control, and may improve scalability, response time, and reduce the possibility of human error for both ADR and ISAM. This work lays the necessary groundwork for developing a machine learning (ML) model for autonomous rendezvous by creating a labeled image …

Design For Extrusion-Based Additive Manufacturing: Generation Of Guidelines For Ceramics With Comparison To Thermoplastics, Hollis Hervey Waites

Masters Theses

"Design for Additive Manufacturing (DfAM) has made much progress for polymer material extrusion processes (MEX-P), like Fused Deposition Modeling (FDM), but very little progress for ceramic MEX processes (MEX-C) like Direct Ink Writing (DIW). This thesis leverages MEX-P design guidelines to create an initial set of design guidelines for DIW. FDM and DIW processes and material properties are compared, and the effect of these factors on the differences in rules is discussed. Five design guidelines are identified as applying to all MEX. For three of these, an exact limit for DIW of alumina is studied: minimum corner radius in the …

Specialty Glass Fibers For Optical Applications, Theodore Carver Lewis

Masters Theses

"Fibers were draw from melts of a commercial Na-aluminosilicate for ion-exchange treatments. A process was developed to draw 100-meters of fiber with a diameter of 100±10m. The fibers were sectioned for ion exchange treatments. SEM analysis showed an ion penetration depth of 45um after 4 hours of ion exchange in a 400°C KNO3 salt bath. The pristine and ion-exchanged fibers were characterized by a two-point bend test in room temperature air with controlled relative humidity (RH) and faceplate velocities between 100 and 4000 μm/s to characterize fatigue effects. Pristine fibers tested in air (40% RH) at 4000 μm/s had failure …

Near-Field Scan Method For Radiated Susceptibility Analysis And The Design And Optimization Of A Miniaturized Spiral Antenna For Ultra-Wideband Applications, Mckennan Edward Starkey

Masters Theses

"The work presented in this thesis consists of two separate topics. The first topic is a new method for the characterization of radiated susceptibility of electronic devices, while the second topic is on antenna design. The first topic proposes an approach to experimentally determine locations within an electronic system that are well coupled to external far-field radiators. This method is performed by using a differential magnetic field probe to sweep across the target device while measuring the total radiated power (TRP) produced by the device in a mode stirred tent. Scan locations where the TRP is larger than the background …

Characterizing A Delay-Programmable Two-Color Femtosecond Light Source For Coherent Control Of Atomic Multi-Photon Ionization Processes, Mason Tanner Toombs

Masters Theses

"In this work a delay-programmable two-color femtosecond laser based on a chirped-seed noncollinear optical parametric amplifier was characterized. This design utilizes a titanium-sapphire crystal oscillator to generate broadband pulses of light spanning approximately 600-1200 nm, with a pulse duration of ~5 fs, repetition rate of 80 MHz, and pulse energy of ~2.5 nJ. An infrared portion of the light, spanning approximately 1020-1060 nm, is split off from the pulse and used to generate a pump beam. By dispersing the remaining seed beam and controlling the relative timing delay between the seed and the pump, tunable frequencies within the seed can …

Optical Fiber Eaf Refactory Lining Temperature Monitoring For Safety And Operating Efficiency, Manoj Kumar Pullagura

Masters Theses

"Electric arc furnace (EAF) sidewalls experience severe thermal, chemical, and mechanical loading, especially near burner and injector regions where refractory wear and water ingress from damaged cooling components pose safety risks. Conventional thermocouples and resistance temperature detectors provide reliable point measurements but lack the spatial resolution needed to capture steep gradients and localized anomalies. This research investigates embedded optical fiber sensors for high-resolution temperature monitoring of EAF refractory safety linings to support early water-leak detection and assessment of refractory thermal behavior. A combined Rayleigh backscattering-based optical frequency domain reflectometry (OFDR) and fiber Bragg grating (FBG) approach was evaluated through laboratory …

Castrip Process Technology: Non-Grain Oriented (Ngo) Si Steels Extension And Carbide-Free Bainitic (Cfb) For Flat Products, Naram Naidu Meesala

Masters Theses

"This research explores the development of advanced steel grades manufactured through Castrip® twin-roll thin strip casting technology, with particular attention to non-grain-oriented electrical Si-Steels (NGOES) and carbide-free bainitic (CFB) steels. The Castrip® process offers a near-net-shape route for producing thin steel strips, which greatly decreases the number of processing stages, lowers energy demand, and reduces carbon dioxide emissions when compared with traditional steel production methods.

In the NGOES part of the study, several industrial Fe–Si steel compositions were cold rolled to final thicknesses ranging from 0.35 mm to 0.15 mm. These materials were then exposed to short-duration continuous annealing at …

Structured Decomposition And Efficient Adaptation For Scientific Data Movement: From Transfer Concurrency To Genomic Data Acquisition, Rasman Mubtasim Swargo

Masters Theses

"The end-to-end performance of scientific data movement is increasingly limited not by raw network capacity but by whichever resource along the path is momentarily slowest, a bottleneck that no single static configuration can track. This thesis argues that the right response is to decompose each problem along the resource or workflow axis where bottlenecks vary, adapt only the genuinely dynamic control variables at runtime, and make that adaptation efficient through utility-guided or offline-learned control rather than expensive online search. The thesis develops this principle through four systems of widening scope. AutoMDT decomposes a transfer by operation, assigning separate concurrency levels …

Moth Assemblages Of Fort Leonard Wood, Missouri, Kimberly Anne Steese

Masters Theses

"Moths (Lepidoptera) are ecologically important insects that function as herbivores, pollinators, prey resources, and indicators of ecosystem integrity. Despite their ecological significance, moth communities in the Missouri Ozarks remain poorly documented, particularly within military-managed landscapes. This thesis examined patterns of moth diversity, assemblage structure, and environmental drivers at Fort Leonard Wood (FLW), Missouri, while also assessing the distribution and genetic diversity of species within the genus Papaipema.

Field surveys were conducted from 2019 through 2021 across prairie, savanna, forest, and restoration habitats at FLW using UV bucket traps, sheet trapping, and targeted larval surveys. Across all sampling efforts, 29,116 individual …

General Approach To Determining The Embodied Energy Of Refractory Products, Jacob A. Kerr

Masters Theses

"Refractories are an important group of engineered materials that are critical for sustaining life in the modern age. These products are key components in many industrial processes, such as the production of steel, cement, glass, aluminum, copper, lead, and many others. It is estimated that 50 million tons of refractory products are produced and used around the world every year. Of this, an estimated 28 million tons of spent refractory is generated after use, much of which ends up in landfills all over the globe. By utilizing embodied energy methodologies, a complete sum of energy inputs can be mapped throughout …

Elevated Temperature Flexure Behavior Of Continuous Carbon Fiber Reinforced Zrb2–Zrsi2 Ultrahigh Temperature Ceramic Matrix Composites, Jacob Stacy, Aaron Ginsparg, Jason Lonergan, Jeremy Watts, Gregory Hilmas

Materials Science and Engineering Faculty Research & Creative Works

Ultrahigh temperature ceramic matrix composites (UHTCMCs) were fabricated from unidirectional prepreg tapes consisting of a matrix of ZrB₂ with 5, 10, and 15 vol.% ZrSi₂ additions and continuous polyacrylonitrile carbon fibers and were densified at 1600°C in a hot press. The relative matrix densities ranged from 88% to 93% with interlayer spacings of ∼72 µm and fiber volume fractions between 30% and 36%. Phenolic resin additions were utilized to react with ZrSi₂ acting as a transient sintering aid to form ZrC and SiC phases. Elastic moduli of the UHTCMCs decreased with increasing temperature during 4-pt flexure testing. …

Quantitative Grain Structure And Texture Analysis Of Hot-Pressed Zrb2 Via 3d Ebsd, Randi Swanson, Michael Chapman, Yue Zhou, Ashley Hilmas, Lisa Rueschhoff, Michael Uchic, William Fahrenholtz, Scott J. Mccormack

Materials Science and Engineering Faculty Research & Creative Works

Understanding and controlling the grain structure of ZrB₂ is critical for optimizing its mechanical and thermal performance in high-temperature applications. Fully dense ZrB₂, densified by hot pressing at 2150˚C and 32 MPa, was analyzed in three dimensions using electron backscattered diffraction, electron and optical microscopy, and mechanical polishing serial sectioning. Grain size followed a gamma distribution, with extreme deviations observed only in the largest 0.1% of grains. Large grains exhibited plate-like morphologies, with the shortest-to-longest axis ratio converging to ∼0.4 as grain volume increased. This work revealed a crystallographically controlled growth mechanism orthogonal to [0001] that is …

Simulated Lunar Gravity Testing Of A Magnetic And Electrostatic System For Beneficiating Lunar Regolith, Blake A. Coffman, Gabriel Porter, Lindsay Manteufel, Mitchell Cottrell, Jeffrey D. Smith, David J. Bayless, William Shonberg, Frank D. Han, Fateme Rezaei, Kirby Runyon

Materials Science and Engineering Faculty Research & Creative Works

We present the design and testing of a lunar regolith beneficiation device that utilizes magnetic and electrostatic separation methods to concentrate desired minerals by removing unwanted material, such as the mineral anorthite, from bulk lunar regolith. The beneficiated materials would have value for downstream in-situ resource utilization (ISRU) processes such as metal extraction, oxygen extraction, and metal oxide additive manufacturing processes. The apparatus uses a dual-strength magnet system with N52 and N42 neodymium magnets to separate particles by magnetic susceptibility. The electrostatic separation system, which acts like a sieve, sorts the regolith simulant by particle size using a single-phase 50% …

The Effects Of Mold Flux Contamination On Oxide Scale Formation And Hydro-Descaling Efficiency During Steel Processing, Tochukwu Princewill Ojiako, Richard Osei, Mario Buchely, Haiming Wen, Simon Lekakh, Ronald O'Malley

Materials Science and Engineering Faculty Research & Creative Works

Oxide scale formation during thin-slab continuous casting has a complex structure, which is influenced by mold flux contamination, that modifies interfacial reactions during solidification, subsequent reheating, and descaling. While individual aspects of the oxidation behavior of carbon steel have been previously examined, the synergetic effects of mold flux contamination during continuous casting and subsequent reheating on scale modification and the efficiency of hydraulic descaling remain inadequately studied. This study quantitatively examines the effect of flux composition on oxide scale evolution, adhesion, and hydraulic removal in low-carbon steel under simulated industrial conditions. Slab samples with as-cast, cleaned, and flux-coated surfaces were …

Quantum Critical Behavior Of Diluted Quasi-One-Dimensional Ising Chains, Logan Sowadski, Thomas Vojta

Physics Faculty Research & Creative Works

(Formula presented.) (Formula presented.) is a unique magnetic material. It features bulk 3D magnetic order at low temperatures, but its quantum critical behavior in a magnetic field is well described by the 1D transverse-field Ising universality class. This behavior is facilitated by the structural arrangement of magnetic (Formula presented.) ions in nearly isolated zig-zag chains. In this work, we investigate the effect of random site dilution on the critical properties of such a quasi-1D quantum Ising system. To this end, we introduce an anisotropic site-diluted 3D transverse-field Ising model. We find that site dilution leads to unconventional activated scaling behavior …

Emergent Spin Fluctuation And Structural Metastability In Self-Intercalated Cr1+Xte2 Compounds, Clayton Conner, Ali Sarikhani, Theo Volz, Mathew Pollard, Mitchel Vaninger, Xiaoqing He, Steven Kelley, Jacob Cook, Avinash Sah, John Clark, Hunter Lucker, Cheng Zhang, Paul Miceli, Yew San Hor

Physics Faculty Research & Creative Works

Intercalated van der Waals (vdW) magnetic materials host unique magnetic properties due to the interplay of competing interlayer and intralayer exchange couplings, which depend on the intercalant concentration within the van der Waals gaps. Magnetic vdW compound chromium telluride, (Formula presented.), has demonstrated rich magnetic phases at various Cr concentrations, such as the coexistence of ferromagnetic and antiferromagnetic phases in (Formula presented.) (equivalently, (Formula presented.)). The compound is created by intercalating 0.25 Cr atom per unit cell within the van der Waals gaps of (Formula presented.). In this work, we report a notably increased Curie Temperature and an emergent in-plane …

Five Tensions Of Artificial Intelligence Adoption For Organ Allocation: Applying The Technology–Organization–Environment Framework, Amaneh Babaee, Daniel Burton Shank, Casey I. Canfield, Joely Grace Hall, Krista L. Lentine, Henry Randall, Mark Schnitzler

Psychological Science Faculty Research & Creative Works

Background: The US organ transplantation system is pursuing modernization of the allocation process through the integration of new technologies such as artificial intelligence (AI). However, the legal and ethical issues within the transplantation industry are still of concern. Objective: We explore the opportunities and challenges for Organ Procurement Organizations (OPOs) to adopt AI. The US organ transplant system is a highly regulated industry yet open to innovation. Methods: Ten structured interviews were conducted with OPO representatives using the Extended Technology, Organization, Environment (TOE) framework. Results: Overall, we identified five core tensions in AI adoption: (1) misconceptions, (2) approach to training, …

Synthesis Of The Naga(S1−Xsex)2 Solid Solution From Mechanically Activated Precursors, Louisiane Verger, Julien Trébosc, Santhoshkumar Sundaramoorthy, Amitava Choudhury, Olivier Hernandez, Eric Furet, Sébastien Chenu, David Le Coq, Laurent Calvez, Olivier Lafon

Chemistry Faculty Research & Creative Works

NaGaS₂ and NaGaSe₂ are two recently discovered compounds that crystallize in the same structure type. In this work, NaGa(S_1−xSe_x)₂ (x = 0.5, 0.75 and 1) are prepared using an alternative synthesis route, mechanochemistry followed by heat treatment. Na₂S, Na₂Se, Ga₂S₃ and Ga₂Se₃ are milled in stoichiometric proportions. Differential scanning calorimetry, X-ray diffraction and solid-state nuclear magnetic resonance (²³Na and ⁷¹Ga) show that the compounds after milling are composed of crystalline NaGa(S_1−xSe_x)₂ with an amorphous part. …

Managing Green And Sustainable Construction Projects: A Computational Analysis Of Associated Risks And Challenges For Improved Performance, Bahaa Chammout, Islam H. El-Adaway

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Green and sustainable building practices have emerged as effective strategies to address the environmental challenges posed by the construction industry. This includes unsustainable resource utilization, excessive waste production, greenhouse gas emissions, and high energy consumption. However, the integration of green and sustainable initiatives in construction introduces distinct risks and challenges that affect project management and may lead to claims and disputes. To this end, and while previous research examined dispute causation across various aspects of the construction industry, there is limited investigation of the unique and complex nature of risks and challenges - and consequently conflicts, claims, and disputes - …

Managing And Accelerating The Circular Economy Transitions Within The Construction Value Chain Using Network Governance And Game Theory Systems Perspectives, Radwa Eissa, Islam H. El-Adaway

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The fragmented nature of the construction industry has hindered its transition toward circular economy (CE) practices. While game theory (GT) has been successfully applied to support the strategic decisions of CE transitions in other sectors, CE-GT models in the construction domain remain extremely limited. This paper addresses two research questions: (1) how are CE network governance activities currently modeled using GT across domains? (2) How can such models be transferred and adapted to solve strategic interactions within the construction value chain in a manner that enables CE practices to emerge as equilibrium outcomes? These questions are driven by the need …

Exploring New Poly-Anion Based Materials For Lithium – Ion Battery Cathodes, Sutapa Bhattacharya

Doctoral Dissertations

The escalating global demand for sustainable energy storage solutions has driven intensive research into novel electrode materials. Polyanion-based cathode materials have emerged as promising candidates due to their structural stability, safety, and voltage tunability enabled by the inductive effect of polyanionic groups. This research explores the synthesis, crystal structure, and electrochemical performance of new polyanion-based cathode materials featuring vanadium, molybdenum, and iron within phosphate and selenite frameworks.

Novel selenite-based materials, such as LiFe(SeO₃)₂ and Li₀.₂₅V₂O₃(SeO₃)₂, were synthesized and characterized, revealing stable electrochemical cycling associated with Fe2+/Fe3+ and V⁴⁺/V⁵⁺ transitions. Additionally, a systematic investigation was conducted on molybdenum phosphate compounds, including …

Zirconium Carbide Based Materials For Extreme Aerospace Environments, Nathaniel Hyman Blatt

Doctoral Dissertations

This research focuses on the processing and properties of zirconium carbide-based materials to promote their use in extreme environment aerospace applications, including nuclear thermal propulsion and hyper sonics. Several carbide systems including ZrC, ZrC-Mo cermets, (Zr, Nb)C, and a high entropy carbide were developed. The ZrC-Mo cermet was studied extensively to understand the effect of starting carbide grain size on the final microstructure, composition, elastic moduli, hardness, fracture toughness, room and elevated temperature flexural strength, thermal diffusivity, electrical resistivity, thermal expansion coefficient, and thermal conductivity. It was shown that heat transport in the cermets was dominated by the ZrC phase …

Essays On Accelerated Failure Time Models For Recurrent Event Data, Emmanuel Masavo Djegou

Doctoral Dissertations

Recurrent event data arise in many fields such as medicine, reliability, insurance, and economics, where the same event may occur repeatedly for a subject. Accelerated Failure Time (AFT) models provide an intuitive framework for relating covariates to event times and offer a useful alternative to proportional hazards models, allowing direct prediction of event timing under right censoring. However, existing AFT extensions for recurrent events, such as accelerated gap time (AGT) models, often fail to account for interventions between events and may not capture complex temporal patterns.

In this work, we first propose a class of semiparametric AGT models incorporating an …

Evaluating The Use Of Machine Learning For Road Maintenance Cost Estimation, Shahla Shirinzad, David Enke

Engineering Management and Systems Engineering Faculty Research & Creative Works

Accurate estimation of highway maintenance costs is essential for efficient resource allocation and long-term infrastructure sustainability. This study evaluates the effectiveness of advanced machine learning models, including ResNet, Transformer, and other neural network architectures, for forecasting maintenance costs using historical data from the Highway Maintenance Improvement Program (HMIP) provided by the North Carolina Department of Transportation (NC DOT). A comprehensive comparative analysis is conducted across multiple models using standard performance metrics, including R², MAE, RMSE, and MSE. The results demonstrate that advanced architectures, particularly ResNet and Transformer, consistently outperform traditional statistical approaches and baseline machine learning models, achieving …