Digital Commons Network^™

Enhanced Pulsar Timing Precision For The Era Of Nanohertz Gravitational Wave Astronomy, Sofia V. Sosa Fiscella

Theses

In 2023, several international collaborations comprising the International Pulsar Timing Array achieved a major scientific milestone with the first detection of a signal in pulsar timing observations consistent with the signature expected from a stochastic gravitational wave background, created by an ensemble of unresolved supermassive black hole binaries in the early Universe. The next breakthrough in the field is expected to be the first detection of a continuous wave from a single such binary, which would allow us to better understand their evolution and that of our Universe. However, this feat will require unprecedented precision in our timing measurements. To …

Understanding Computer-Mediated Human Experience In Digital-Physical Hybrid Space, Jiangnan Xu

Theses

With the rapid development of mobile and immersive technologies, the boundary between the digital and real world is increasingly blurred, giving rise to hybrid spaces. Hybrid spaces have permeated daily life and reshaped spatial meaning-making and social interaction. Despite their growing prevalence, empirical understanding of human experiences in hybrid spaces remains limited. If left unexamined, hybrid spaces risk becoming technology-centered rather than human-centered environments that overlook socio-cultural dimensions, potentially leading to harmful consequences for individuals and society. To investigate human experience in hybrid spaces, this thesis comprises five studies and uses gameful systems as research probes. Prior literature identifies collaboration …

Phytoremediation Potential Of Selected Plant Species (Ambrosia Artemisiifolia L. And Erigeron Canadensis L.) For Reducing Priority Heavy Metal And Metalloid (As, Cd, Cr, Cu, Hg, Pb, Zn) Contamination In Anthropogenically Impacted Soils Of Ukraine, Volodymyr Laptiev

Theses

Soil contamination with priority heavy metals and metalloids of anthropogenic origin represents one of the most pressing environmental challenges of the present day, directly associated with risks to public health, ecosystem degradation, and the achievement of the Sustainable Development Goals, particularly those of the World Health Organization and the United Nations aimed at ensuring a healthy environment, safe ecosystems, and sustainable land management. Under conditions of long-term technogenic pressure, compounded by the additional impact of military activities on the territory of Ukraine, the search for scientifically substantiated, environmentally safe, and economically feasible approaches to reducing soil contamination has become especially …

A Complex Systems Integration Analysis Approach, Tamia Neal

Theses

It has been said that if the building blocks of a system were designed and implemented correctly, then their subsequent integration would be straightforward. The complex systems integration analysis approach presented in this thesis provides the mechanisms to construct those blocks. A spectral clustering algorithm is used to cluster elements into modules, and the normalized integrative complexity metric is used to evaluate the portion of structural complexity that can be attributed to integrating a system from its modules. Together, the algorithm and metric identify which aggregates of system elements reduce the complexity of the integration effort. The proposed integration analysis …

Evaluating The Operational Performance Of Diverging Diamond Interchanges Under High Heavy Vehicle Traffic Using Synchro Traffic Simulation Software, Hannah Duke

Theses

Diverging Diamond Interchanges (DDIs) are increasingly used to improve traffic flow and safety, particularly where left-turn volumes are high. However, their operational performance under high heavy vehicle percentages has not yet been evaluated. This thesis investigates the impact of varying HV percentages and traffic volumes at a sample DDI location. Traffic simulation using Synchro software was used to model the DDI under scenarios with varying heavy vehicle percentages and varying volumes. This approach allowed evaluation of traffic growth and increasing heavy vehicle presence on DDI performance, capturing realistic operational conditions for freight-heavy corridors. Key performance measures included average control delay, …

Spatially-Distributed Imu Array Navigation : Virtual Imu And Federated Approaches With Applications To Uncrewed Aerial Systems, Jackson Neese

Theses

This thesis investigated lever arm effects on distributed inertial measurement unit (IMU) array navigation and evaluated the performance of multiple fusion architectures with applications to uncrewed aerial systems (UAS). The Kalman Filters comprise of three filters: a naive baseline, a filter tracking lever arm as a filter state, and a filter constraining lever arm state estimates around known values. These filters feed into a virtual IMU fusing raw measurements and a federated filter combining output states. Each are evaluated with equal, static, and dynamic weighting based on lever arm and sensor noise. Experiments on indoor and outdoor UAS datasets reveal …

Real Time Temperature Measurement Of Weld Nugget During Friction Stir Welding Operation Using Ultrasonic Thermometry, Daniel Tyler Aiken

Theses

Friction Stir Welding (FSW) is a solid-state joining process widely used for aluminum alloys in aerospace and structural applications due to its ability to produce high-quality joints without melting. The thermal history of the weld tool and surrounding material plays a critical role in governing material flow, microstructural evolution, and resulting mechanical properties. However, accurate measurement of temperature at the tool–workpiece interface remains challenging due to the transient nature of the process, geometric constraints, and ability to obtain subsurface temperature. This thesis investigates the use of ultrasonic thermometry as a non-destructive, high-temporal-resolution method for measuring time dependent, site-specific temperatures from …

Modelling Novel Planar Nozzle Geometries For A Z-Pinch Fusion Propulsion System, Stephanie Manasterski

Theses

Interplanetary travel using chemical or electrical propulsion faces two major obstacles: the long mission timelines and the health risks to human crews from prolonged radiation exposure. Fusion propulsion offers a potential solution through high specific impulse and moderate thrust values. Z-pinch fusion, a pulsed magneto-inertial fusion approach, is promising for propulsion as the plasma is confined through current-driven compression, eliminating the need for external confinement coils to achieve ignition conditions, and the confinement configuration is simple. A 3-dimensional model of a novel linear magnetic nozzle geometry was developed with the propellant, dissociated ammonia, oriented sideways in the nozzle, assuming prior …

System-Level Analysis And Experimental Testing Of A Rotating Detonation Rocket Engine With Water Electrolysis Propellants, Justin M. Byers

Theses

This work explores the potential benefits and practical feasibility of a rotating detonation rocket engine (RDRE) spacecraft thruster using water electrolysis for propellant generation. Such a thruster can enable the use of liquid water as an easily storable and chemically inert propellant, as well as the volume and efficiency benefits associated with detonation combustion. A thermodynamic model is first developed to demonstrate the compounding advantages of both water electrolysis propellant generation and detonation combustion when compared to conventional isobaric combustion cycles. Comparisons are also drawn to alternative water-powered propulsion methods and the advantages of chemical propulsion are observed. The representative …

Down The Rabbit Hole : A Journey Of Writing And Liberation, Mckenzie Sharp

Theses

Down the Rabbit Hole: A Journey of Writing and Liberation is a hybrid creative thesis composed of poetry, memoir, and auto-fiction that explores trauma, mental illness, abuse, and resilience through non-linear narrative and surrealist imagery. This collection examines writing as both a survival practice and reclamation of agency after prolonged silencing by drawing on feminist theory, trauma studies, and experimental literature techniques. Structured as an anthology, the thesis mirrors fractured memory and identity and the cyclical nature of healing. Organized into three chapters— “Awakening,” “Deconstruction,” and “Enlightenment”—the collection traces recognition of harm, dismantling of inherited belief systems, and the ongoing …

Transformation Of Public Earth Datasets For 3d Narrative Visualization Of Disaster Events, Connor Bleisch

Theses

Communicating large datasets in ways that are appealing to non-scientific audiences has been a recent focus of big data visualization. Interest has grown for using 3D environments with game-like structures and immersive technology like AR and VR since they are more engaging. We introduce a method, based on the structure of the datasets and domain knowledge of the natural phenomena, for transforming public National Aeronautics and Space Administration (NASA) Earth datasets into 3D narrative data visualizations, specifically of disaster events. Two visualizations were created using this method: one of the KNP Complex Wildfire in 2021 and one of Hurricane Beryl …

The Influence Of Defendant Mental Illness Characteristics On Prosecutorial Decision Making, Claire Elise Martin

Theses

As most criminal cases are now resolved via plea-bargaining, research on legal decision making has extended beyond the jury to evaluate judges, defense attorneys, and prosecutors. Although legal actors are obliged to remain objective and dispassionate, extralegal factors regarding defendant characteristics (e.g., age, gender, race/ethnicity, socioeconomic class) can influence case outcomes. Extant research on the effect of defendant mental health status and defendant demeanor on sentencing outcomes in court hearings is limited. Therefore, the present experiment solicited 134 prosecutors in a vignette study designed to assess how extralegal characteristics, specifically those related to mental illness, may affect the punitiveness of …

Application Of A Scale-Resolving Turbulence Model To Supersonic Retropropulsion Flows In Earth And Martian Atmospheres, Rebecca Thompson

Theses

The Blended Partially-Averaged Navier-Stokes (BPANS) turbulence model was used to simulate complex turbulent compressible flows seen in supersonic retropropulsion (SRP). The model was incorporated in the OpenFOAM solver sonicFoam to investigate SRP flows in Earth and Martian atmospheres. The new sonicFoam with BPANS was first tested for subsonic flows using the shear flow benchmark case of flow around a cylinder. Results show good agreement of velocity profiles with experimental values. SonicFoam was then validated for compressible flows using an experimental SRP configuration. Pressure coefficient distribution along the forebody and aft body of the geometry show good agreement with experimental results. …

Nandworks : A Low-Cost Testbed For Interfacing Onfi-Compatible Nand Flash Memory Devices, Mark Scheidker

Theses

NAND flash memory is the basis for modern digital storage, but direct access to raw flash functionality remains difficult due to limitations in available interface tools. Industrial characterization systems can issue low-level commands but are prohibitively expensive for most researchers and students. USB-based bit-banging tools lack the timing fidelity needed for certain experiments. This thesis introduces NANDWorks, a testbed based on the Raspberry Pi 4 that provides direct access to ONFI-compatible NAND flash devices via GPIO bit-banging in Linux user space, building on prior work for the Terasic DE1-SoC platform. NANDWorks has a layered software stack that includes a hardware …

Development And Validation Of An Automated Image-Based Framework For Bubble Size And Velocity Measurement In Centrifugal Nuclear Thermal Rocket Experiments, Olivia Williams

Theses

Accurate measurement of bubble size and rise velocity is essential for characterizing multiphase flow behavior in Centrifugal Nuclear Thermal Rocket (CNTR) experiments, where dynamic imaging conditions complicate traditional analysis methods. This thesis presents the development and validation of an automated image-based framework for extracting bubble equivalent diameter and rise velocity from high-speed experimental videos of injected gas bubbles rising through controlled liquid-filled volumes. Representative datasets include air bubbles injected into water and Sodium Polytungstate (SPT-3). The framework employs a staged analysis workflow with instance-level bubble segmentation using a Mask R-CNN model, secondary classification for detection verification, multi-object tracking, and velocity …

Modeling And Characterization Of Pond And Fresh Ash Leaching In Citric Acid, Christina Fleming

Theses

Resourcing rare earth elements (REEs) from coal ash offers the opportunity to recycle industrial waste and reduce national dependence on foreign suppliers. In this research, the leaching behaviors of pond and fresh ash were studied to evaluate their suitability for REE recovery. Concentrations of REEs in leachates were measured and compared to kinetic models from literature, and the ash was analyzed using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) to characterize the observed behaviors. The pond ash leachate exhibited lower REE concentrations with steady release patterns, likely due to the acid resistant, REE-bearing aluminosilicate glass phases. In contrast, the …

Experimental Characterization Of Gas-Injected Bubble Dynamics In Various Fluids And Injector Arrays For Centrifugal Nuclear Propulsion Applications, Julia Kondrat'yev

Theses

This study experimentally characterizes gas-injected bubble dynamics in analog fluids to establish baseline behavior for Centrifugal Nuclear Thermal Propulsion (CNTP) systems. Nitrogen was injected through mass flow ranges of 3.3E-05 to 9.6E-05 lbm/s through various injector arrays in a transparent tank apparatus using water or sodium polytungstate (SPT-3) to vary fluid properties. Four injector configuration cases were tested on a 4-in deep, clear-sided chamber at atmospheric surface pressure to examine the effects of fluid viscosity and density, circular injector diameter, injector location, and mass flow rate on bubble diameter, rise velocity, and plume structure. Bubble equivalent diameters, positions, and velocities …

Optical Turbulence Estimation From Numerical Weather Prediction Models: Methods And Error Analysis, Richard Minor

Theses

Optical turbulence plays a critical role in electromagnetic wave propagation through the atmosphere, directly affecting imaging systems, wireless communications, and high-energy laser (HEL) performance. Realistic three-dimensional characterization of atmospheric turbulence is essential for understanding these impacts, particularly within the atmospheric surface layer, where turbulence is often strongest. The refractive index structure parameter, Cn2, is used to quantify optical turbulence. This thesis evaluates the capability of the High Resolution Rapid Refresh (HRRR) model to characterize surface layer Cn2. As the highest resolution and most frequently updated numerical weather prediction model covering the continental US, HRRR offers strong potential for operational HEL …

High Strain Rate Behavior Of Soft Polymeric Materials : Polymer-Bonded Explosive Simulants And Polyimide Aerogels, Benjamin Jeffrey Solomon

Theses

Soft polymeric materials exhibit strain sensitive behaviors and are used in various applications where dynamic loading conditions may be present, making understanding the responses at high rates vital to safe application. Investigation of the mechanical response of soft materials at high strain rates has proven challenging due to low forces, mismatching impedances, and longer times to obtain dynamic force equilibrium limiting the quality and accuracy of data acquisition. Two polymeric materials were evaluated in this study. The first is polymer-bonded explosive (PBX) 9501, which experiences dynamic loading during use as solid propellant and warhead explosive material. It is found that …

Intercomparison Of Remote Sensing Methods For Calculating Cn² Profiles, Isaiah Joseph Montgomery

Theses

Propagation of electromagnetic waves through the atmosphere is affected by turbulence. The impact of turbulence on wave propagation is characterized by the refractive index structure function (Cn²), which characterizes the intensity of fluctuations of the refractive index of air due to turbulence. Observations of vertical profiles of Cn² are essential for evaluating numerical model predictions. This study presents an intercomparison of Cn² derived from multiple ground-based remote sensing systems, including 915 MHz profiler, sodar, and a parameterized method that uses doppler wind lidar and radiometer. Results indicate that the sodar is the most accurate near- surface Cn² profiler, but above …

Influences Of Charge Structure And Storm Microphysics On The Relationship Between Optical And Vhf Lightning Observations, Kaitlyn Wheeler

Theses

Lightning observations provide valuable insight into convective intensity, storm structure, and microphysical processes. Much of the current understanding of lightning-convection relationships is derived from ground-based very high frequency (VHF) measurements, while space-based optical observations remain comparatively new. This study investigates how storm charge structure and microphysics influence observed optical lightning emissions using coordinated observations from the 2017 GOES-R Post Launch Test campaign. Optical measurements from the Fly’s Eye Geostationary Lightning Mapper Simulator were combined with Lightning Mapping Array observations for ordinary multicell storms exhibiting a normal charge structure on 18 April 2017 and a supercell exhibiting an anomalous charge structure …

Impacts Of Vertical Wind Shear And Coastal Friction On The Pre-Landfall Rapid Intensification Of Hurricane Nicholas (2021), Ethan O. Prunty

Theses

Predicting tropical cyclone (TC) rapid intensification (RI) under moderate-to-strong vertical wind shear (VWS) remains challenging, particularly when cyclogenesis and RI occur within 48 hours of landfall, as with Hurricane Nicholas (2021). This study analyzes Nicholas’ RI using NOAA’s Hurricane Analysis and Forecast System. Results reveal a two-stage vortex alignment before the early RI stage: diabatic heating first draws the mid-level center toward the low-level center, followed by cyclonic precession. A nearly-saturated core below 500 mb develops before RI onset as column-integrated moist static energy (MSE) increases, and the moistening process continues during the early RI stage as surface heat and …

Effects Of Energetic State On Male Mating Preferences In Poeciliid Fishes With Differing Mating Strategies, Katherine E. Taylor

Theses

Reproduction is energetically costly, making condition (i.e., energetic state) a potential factor in shaping reproductive behavior. However, its role in male mate choice remains largely unexplored. Here, we investigate condition-dependent effects on male mate choice in two species of Poeciliids: one coercive species (Gambusia affinis) and one courting species (Xiphophorus hellerii). Diet treatments were used to manipulate male and female conditions, and male preferences were assessed in dichotomous-choice tests using animated female stimuli. X. hellerii males showed a preference for high-condition females, whereas G. affinis males showed no overall net preference. Diet influenced preference in G. affinis, with high-fed males …

Reflux Micro-Aspiration: Natural History, Pathophysiology, Clinical Presentation And Treatment, Oleksandr Khoma

Theses

Background

The accurate diagnosis of gastro-oesophageal reflux pulmonary micro-aspiration has only become possible recently with the introduction of a novel technique of reflux micro-aspiration scintigraphy study combined with single photon emission computed tomography (SPECT) combined with x-ray tomography (CT) in a hybrid instrument (1-3). This has allowed the accurate diagnosis of pulmonary and airway contamination with refluxate. Previously only patients with large volume symptomatic reflux aspiration were diagnosed clinically (Mendelson syndrome) or by 2-dimentional barium meal or an older plantar (2 dimensional) technique of scintigraphic aspiration studies. The concept of reflux micro-aspiration has been implicated in multiple pulmonary diseases but …

Uae Traditional Folklore Through Modern Media And Its Educational Potential: The Case Of Freej, Shahad Imad Mostafa

Theses

This mixed‑methods study examined how the Emirati animated series Freej preserves traditional folklore through vernacular language, dialect, and idiomatic expressions, and evaluated its educational potential. Guided by four questions on folklore representation, dialect/idiom use, the role of the characters, and curricular applicability, the research combined content analysis of selected episodes, interviews coding and a survey of 100 Emirati participants; survey data were summarized with descriptive statistics to triangulate qualitative insights.

Findings indicated that audiences overwhelmingly perceived Freej as linguistically and culturally authentic: 95% rated the dialect as very/somewhat authentic, 94% said it reflects elders’ speech, and 89% felt the series …

Impact And Requirements Of Future Robots In The Urban Realm: Dubai Silicon Oasis Case Study, Abduljalil Abbasi

Theses

Robots are moving from factories and warehouses into the streets, sidewalks, and shared public spaces of cities, and Dubai Silicon Oasis (DSO) is at the forefront of this shift in the Gulf region. Through the Talabat ‘talabot’ autonomous delivery pilot, DSO has demonstrated that sidewalk robots can operate reliably in a hot-climate, mixed-use urban district, but this operational success has outpaced the governance frameworks, spatial design standards, and long-range planning foundations needed to scale deployment safely, inclusively, and sustainably to 2035. This thesis addresses that gap by asking how DSO can design and govern the integration of robots into its …

Enhancing Json Schema Inference Via Semantic And Structural Modeling Of Heterogeneous Data, Justin R. Namba

Theses

Schema discovery is finding the structure of data. It helps users understand the meaning of data and write queries to manipulate it. This is typically easy for relational databases, but complex for non-relational (NoSQL) databases with documents. For relational databases, the schema is predefined because the data they contain is structured, but for NoSQL databases, data is usually unstructured or semi-structured. Here, we focus on a type of semi-structured data called JSON, which is a collection of documents that consists of nested key-value pairs. A JSON key and value are similar to a column name and its associated data instance …

Evaluating Stormwater & Carbon Benefits Of Urban Street Trees, Anthony J. Rodriguez Diaz

Theses

Urban areas experience a multitude of environmental challenges, including flooding and air pollution. In response to these pressures, urban forests have emerged as an essential nature-based strategy to enhance resilience and reduce climate-related risks. The implementation and expansion of urban street trees further contribute to this effort by mitigating stormwater runoff and reducing atmospheric carbon emissions.

Fortunately, advances in environmental modeling have made it increasingly possible to quantify these ecosystem services using specialized software. The United States Department of Agriculture (USDA) Forest Service's i-Tree suite exemplifies this progress. The software provides a comprehensive set of tools designed to quantify environmental …

Heathammer: Effects Of Thermal Stress On Dram Technology Reliability Using Rowpress And Rowhammer, Filip Roth Tronnes-Christensen

Theses

Modern DRAM scaling has reduced cell capacitance and increased thermal sensitivity, making disturbance-based faults such as RowHammer and RowPress increasingly significant reliability and security concerns. RowHammer induces bit flips through repeated row activations, while RowPress does so by holding a wordline open for an extended duration; both exploit inherent capacitive coupling and leakage mechanisms in dense DRAM arrays. This thesis introduces HeatHammer, a thermally assisted disturbance exploit that interleaves RowPress and RowHammer operations to amplify charge leakage and trigger row-traversing bit flips. Using the FPGA-based DRAM-Bender test platform, HeatHammer is evaluated on four commercially available DDR4 modules from different manufacturers …

A Novel Rheological Technique To Measure The Yield Stress In Equibiaxial Elongation, Asher Segal

Theses

Yield stress measurement in non-Newtonian fluids, particularly under complex flow conditions such as equibiaxial elongation, remains a significant challenge in experimental rheology. This work presents the development of a novel method, Continuous Lubricated Squeezing Flow (CLSF), designed to quantify the normal yield stress of viscoelastic materials while minimizing boundary artifacts.

The CLSF method was implemented and validated using Carbopol 940, a model yield-stress gel, at concentrations of 1 wt% and 2 wt%. Comparative shear rheology was first performed to establish baseline yield stresses and verify sample integrity. CLSF experiments were then conducted over controlled flow rate increments and gap distances …