Digital Commons Network^™

Structural Design And Development Of Deployable Propeller Blade, Annan Mashin

Graduate Studies Theses and Dissertations 2026

Aerospace systems frequently face competing requirements between compact packaging and high aerodynamic performance. Large propellers improve efficiency and thrust generation, yet launch constraints and confined storage volumes limit their maximum span. Conventional deployable solutions rely on hinges, locking mechanisms, and external actuation, increasing mechanical complexity and reducing reliability. This dissertation investigates an alternative approach in which elastic instabilities in thin composite shells are deliberately harnessed to enable rapid, mechanism- free deployment of aerodynamic structures. This work harnesses propagating instability in open- section thin-walled airfoil geometries to enable reversible transformation between compact stowed and stiff deployed configurations. By tailoring structural architecture, …

The Revelations, Lily Mckenna

Graduate Studies Theses and Dissertations 2026

The Revelations is a self-actualization in the form of a poetry collection. The speaker’s realization that reality is relative arrives through a Title IX case against an abusive boyfriend and former bandmate. Poems such as “Complainant / Respondent” use rigid legal structures to investigate the fluidity of truth and perception and how they can be manipulated. With her band on hiatus and the case propelling her into a new world, the speaker starts running DIY shows alongside a cast of characters with a shared love of music. She interrogates their realities in the character studies “On The Relative Reality Of…,” …

Deceptive Design And Disability: How Dark Patterns Affect Users With Visual Impairments, Konstantin Metz

Graduate Studies Theses and Dissertations 2026

Dark patterns are deceptive interface designs that steer users toward unintended actions, often at financial or privacy cost. This thesis examines how those that are vision impaired are at greater risk of these dark patterns given their visual acuity deficit. We conducted semi structured interviews with nine participants across common contexts including e-commerce checkout, subscription and cancellation flows, software download pages, and mobile permission prompts. The data show recurring exposure to dark patterns such as hidden or de-emphasized fees, pre-selected add-ons, deceptive advertising and fake download buttons along with unequal consent paths, repeated permission nagging, and cancellation friction. Participants reported …

Chemical Kinetic Experiments Of Monomethyl Hydrazine Combustion Products At High Pressures And High Temperatures In A Shock Tube, Cooper Q. Mills

Graduate Studies Theses and Dissertations 2026

This study presents experimental shock tube laser absorption spectroscopy data to validate high-pressure and high-temperature chemical kinetic mechanisms for mixtures of H₂/air, NH₃/air, and H₂/CO/NO₂/air diluted in argon (95-98%) at high pressures (5, 10, 25 bar) and high temperatures (1000 to 2150 K). The mixtures were at equivalence ratios of 0.5, 1.0, and 1.5 to cover the range of possible conditions experienced throughout practical combustors. Laser absorption spectroscopy data was measured for NH₃, H₂O, CO, and NO using a novel multi-species setup. Chemical kinetic mechanisms contain the fundamental …

Cfd Investigation Of Heat Transfer Enhancement In Pipes Using Gyroid Tpms Structures For Industrial Steam Generation, Alejandro Moreno Escribano

Graduate Studies Theses and Dissertations 2026

Industrial heating processes account for nearly 28\% of global CO2 emissions, and fossil fueled boilers predominate in high temperature applications. Industrial electrification can be an effective solution when combined with renewable energy sources. Increasing steam generation efficiency and at the same time maintaining system compactness is a significant challenge in industrial thermal processes. Traditional smooth pipes offer limited heat transfer surface area, which constrains boiling heat transfer performance and reduces the overall efficiency of steam generation systems. Advanced internal geometries have the potential to significantly enhance heat transfer by increasing surface area and promoting fluid mixing. This work presents a …

Ignition Delay Time Measurements Of Natural Gas/Ammonia Mixtures At Gas Turbine Operating Conditions, Zachary A. Morris

Graduate Studies Theses and Dissertations 2026

Natural Gas/Ammonia (NG/NH₃) fuel blends are a promising route to reduce CO₂ emissions from gas turbines while leveraging existing NG infrastructure, but their autoignition behavior at elevated pressures is not yet well constrained. This work reports high-pressure shock tube ignition delay time (IDT) measurements for NG/NH₃/Air mixtures at gas turbine-relevant conditions. Experiments were performed at pressures of 5, 10, and 25 bar, temperatures from 1500 to 2100 K, with equivalence ratios of Φ = 1.0, 1.2, and 1.4, and argon-diluted fuel compositions spanning pure NH₃ to NG-rich blends. Experiments were carried out in two …

Revolution In The Age Of Social Media: A Mathematical Model For Information, Dissent, And Stability, Killian Muollo

Graduate Studies Theses and Dissertations 2026

Revolutions, defined by Skocpol as rapid transformations in class, state, and/or social structures, are important world events that can cause civil wars, spark international trends, and result in transitions toward democratic and autocratic regimes alike. They are characterized largely by the mechanism of mass mobilization, which is increasingly facilitated by online networks and digital communication. In this dissertation, we investigate such means and outcomes of revolutions as dynamical systems. We construct three models describing separate but complementary aspects of revolution, beginning at the smallest unit of analysis and then moving outward in scope. First, we construct a graph-based model to …

Sensitivity Analysis Of Tuned And Intentionally Mistuned Blisks To Random Mistuning, Tate A. Myers

Graduate Studies Theses and Dissertations 2026

The vibrational behavior of bladed disks, or blisks, is highly sensitive to variations in its cyclic symmetry due to variations in mass, stiffness, damping, or a combination of these factors. These inconsistencies can arise from manufacturing tolerance inconsistencies, operational wear, impacts during usage, and intentional mistuning. This thesis develops an analysis of the sensitivity of both tuned and intentionally mistuned blisks to random mistuning in their structural properties. Sobol sampling combined with state-space eigen-analysis is utilized to develop a set of randomly mistuned systems. Modal Assurance Criterion is used to track the mode shapes of each randomly mistuned system back …

Evaluation Of Electroencephalography Processing Methods For Estimating Metabolic Energy Expenditure During Walking, Stephanie L. Pinelo

Graduate Studies Theses and Dissertations 2026

In this study, three EEG datasets, created via different levels of pre-processing, were used to train VO2 prediction models whose performance was tested and compared. Understanding the link between EEG and VO2 during walking is important when working in rehabilitation or studying metabolic energy optimization. Common methods of measuring these two bio-signals tend to be bulky, uncomfortable, and inefficient, so finding a way to predict VO2 from EEG via 1D CNN model training is a worthy pursuit.  It was hypothesized that, due to a CNN needing more data to find patterns for prediction, a minimally processed EEG dataset would have …

Adaptability And Applications Of Advanced Laser Absorption Diagnostics In High-Pressure Shock Tube Environments, Lucas R. Pitts

Graduate Studies Theses and Dissertations 2026

Theoretical application and physical implementation of various laser absorption spectroscopy (LAS) diagnostics are examined within a high-pressure shock tube facility. Research focuses on the rationale behind the specific optical alignment layouts used across three distinct experimental campaigns, detailing the methodology required to maintain signal integrity in varied reacting flow environments. The first research campaign addresses the pyrolysis of hydroxyl terminated polybutadiene (HTPB) solid propellant binders for solid fuel ramjet (SFRJ) applications by measuring the species time histories of alkenes and aromatics. Alignment configurations prioritized beam stability and signal strength for the decoupling of overlapping absorption features to ensure measurements accurately …

Study Of Compressibility Of Flames In Scramjet Combustors, Anirudh Ranganathan

Graduate Studies Theses and Dissertations 2026

Viable forms of propulsion for practical hypersonic flight are of great interest in modern times, of which supersonic combustion ramjets(scramjets) are a very advantageous option. Compared to ramjets, which are severely limited by increasing total pressure loss and dissociation effects, scramjets offer a much more efficient form of propulsion in the Mach 6 – 8 regime. Despite this, a common and unmitigated issue facing scramjet technology is scramjet unstart.

Prior investigations researching scramjet unstart have elucidated global heat release considerations in relation to total fueling or combustion modes as a result of global heat release . Minimal work has been …

Multibody Acausal Framework For Structural Dynamics Of Offshore Support Structures With Hydroelasticity And Soil-Structure Interaction, Saad Rahman

Graduate Studies Theses and Dissertations 2026

Offshore energy systems present significant challenges in support structure design due to their scale and the strong coupling between aerodynamic, hydrodynamic, and structural subsystems. These interactions make traditional sequential modeling approaches inefficient for design exploration. Acausal modeling frameworks address this limitation by enabling direct integration of coupled subsystems without reformulating governing equations, improving computational efficiency while preserving physical fidelity. This supports rapid exploration of large design spaces, accelerates iteration cycles, and shortens the path from concept to deployment.

This thesis develops and validates an acausal multibody elastodynamics model for offshore support structures. The framework includes structural flexibility to capture member-level …

Design And Characterization Of A Jet Nozzle Using Particle Image Velocimetry, Valerie K. Rodriguez

Graduate Studies Theses and Dissertations 2026

This paper presents the design and experimental characterization of the jet exit velocity from a supersonic nozzle injecting into a low-pressure vacuum chamber using Particle Image Velocimetry (PIV). The PIV method is employed to overcome limitations encountered in prior experiments characterizing a jet-in-crossflow, such as qualitative shock visualization and insufficient data on jet exit properties. The previous set of experiments used Classical Schlieren to visualize the flow as well as emission measurement with IR detectors. For the fuel injection cases, particular emphasis is placed on preventing condensation within the injection line and at the nozzle exit due to under expanded …

Shock Tube Speciation Analysis Of Hydrocarbon Mixtures Relevant To Solid Fuel Combustion, Diego N. Ruiz Pena

Graduate Studies Theses and Dissertations 2026

Solid Fuel Ramjets (SFRJs) are often used in tactical applications due to their simplicity, robustness, and reliability. No moving parts, atmospheric oxidizer usage, and scalable fuel grain designs make them a great solution for compact, high-speed air-breathing propulsion systems. SFRJs operate by compressing incoming air through a fixed geometry inlet and directing it over a regressing solid fuel surface, where pyrolysis gases are released and transported downstream to the combustion chamber where thrust is generated. Hydroxyl-terminated polybutadiene (HTPB) is a commonly used fuel binder in SFRJ systems due to its high energy density, stable combustion behavior, and ease of processing. …

A Frequency-Dependent Hydrodynamic Modeling Framework For Offshore Platforms With Optimization-Based Parameter Identification, Md. Rafid-Ul Haque Sakif

Graduate Studies Theses and Dissertations 2026

Accurate prediction of hydrodynamic loads on offshore platforms requires drag coefficients that adequately capture their dependence on wave frequency. However, conventional implementations of Morison’s equation generally assume constant drag coefficients across the entire frequency spectrum, which can lead to inaccuracies in predicting platform responses under complex sea-state conditions. To address this limitation, this study proposes a frequency-dependent hydrodynamic modeling framework in which the platform response is decomposed into distinct frequency regions, specifically low-frequency and high-frequency components. Separate drag coefficients are assigned to each region to better represent the underlying flow physics. The decomposition is achieved using filtering techniques in the …

Modeling Hazard Perception Learning In Novice Drivers With Autism: A Multimodal Simulation-Based Study, Erik J. Sand

Graduate Studies Theses and Dissertations 2026

Young drivers with autism spectrum disorder (ASD) often demonstrate difficulties with road-surveillance behaviors such as scanning ahead, monitoring mirrors, and identifying emerging hazards. These challenges can increase crash risk, particularly for adolescents with limited driving experience. This study explored whether a simple, video-game–based hazard-training program could improve hazard detection performance, visual scanning, and self-regulation in this population. Five participants aged 15–18 years, each identified by a parent as having ASD and possessing either a learner’s permit or no license, completed sequential Baseline, three Treatment, and Withdrawal phases using the SpeedLimit driving simulation. The study employed a single-case experimental design with …

Bond Behavior Of Uhpc-Nsc Interfaces For Bridge Deck Repair Under Flexural Loading, Larissa Santiago La Banca

Graduate Studies Theses and Dissertations 2026

The use of ultra-high performance concrete (UHPC) has increased due to its superior mechanical properties and strong bond with normal-strength concrete (NSC). It is widely used as a repair material, particularly in bridge decks, where maintenance remains a challenge. However, the interface between UHPC and NSC is often the weakest region of the composite system and requires careful evaluation.

This study investigates the bond behavior between UHPC and NSC using different surface preparations, test setups, and UHPC materials. The experimental program included unreinforced beams with vertical interfaces tested under three- and four-point flexural loading, and reinforced slabs with horizontal interfaces …

Defect-Guided And Energy-Driven Unfolding With Learning-Based Strategies: From Geometries With Compact Refolding To Garments, Shah Wasif Sazzad

Graduate Studies Theses and Dissertations 2026

Unfolding and folding are related geometric and mechanical transformations fundamental to structural applications. Particularly, unfolding curved surfaces is important for deployable structures, garment pattern generation, etc. A central challenge is minimizing geometric distortion between a surface and its unfolded counterpart avoiding overlaps. As regions of lower Gaussian curvature typically produce less distortion during flattening, identifying curvature distribution becomes essential. Topological defects in a particle assembly on a surface in its minimum interaction-energy configuration indicate regions of concentrated curvature. In this work, an unfolding method is proposed that segments the surface using defects' location. Cutlines connecting the defects isolate lower curvature …

Data-Driven Seismic Site Classification Using Earthquake And Microtremor Horizontal-To-Vertical Spectral Ratios, Sanidhya Sharma

Graduate Studies Theses and Dissertations 2026

The prevailing seismic site classification parameter, the time-averaged shear-wave velocity in the upper 30 meters (V_S30), provides an incomplete representation of site conditions, neglecting deeper geology, impedance contrasts, and resonance phenomena. This thesis developed and validated a data-driven framework for seismic site classification based on the full spectral shape of Horizontal-to-Vertical Spectral Ratio (HVSR) curves combined with unsupervised machine learning, through two complementary research studies. Research 1 applied K-means clustering to earthquake-based HVSR (eHVSR) data from 3,186 ground motion stations across California and adjacent regions, identifying four physically distinct site clusters, characterized by low-frequency, very-low-frequency, high-frequency, and …

Experimental Rate Feedback Control Of A Model-Scale Hourglass-Shaped Heaving Point Absorber, James R. Halverson

Dissertations, Master's Theses and Master's Reports

Buoy geometry greatly affects a point absorber wave energy converter's dynamic response to waves. Finding the optimal buoy shape and control method remains an open research area focused on maximizing the conversion of wave kinetic energy into electricity. This work presents an experimental comparison of closed-loop energy extraction between a cylindrical and a truncated cone buoy, both with the same submerged volume, across various wave frequencies and amplitudes. To ensure a fair comparison, the optimal rate feedback gain is calculated for each buoy at each wave condition. Multiple metrics, including power output, capture width, and actuator force, are used to …

Numerical And Experimental Evaluation Of A Simple, Low-Energy Lunar Volatile Separation Technology, Eleanor L. Zimmermann

Dissertations, Master's Theses and Master's Reports

In-situ resource utilization (ISRU) is the practice of finding, extracting, and using the local resources found on extraterrestrial bodies, such as the Moon and Mars. ISRU enables in-situ production of mission consumables—such as rocket fuel and potable water—which will be critical for establishing a sustainable human presence on the Moon, a goal NASA intends to accomplish by 2028 with the Artemis missions. The separation and liquefaction of locally extracted volatiles—such as water, CO₂, and Methane—is an essential component in lunar surface sustainability, but there are very few technologies being developed for this purpose. This report introduces the Radiative …

Nondestructive Evaluation Of Additively Manufactured Parts Using Resonant Inspection And Frequency Domain-Based Correlation Criteria, Gita Deonarain

Dissertations, Master's Theses and Master's Reports

Additive manufacturing (AM) enables the production of highly customized and geometrically complex components; however, these parts remain susceptible to a wide range of defect types and severities. The combination of complex geometries and distributed defects presents a significant challenge for post-process nondestructive evaluation (NDE). Conventional inspection techniques, such as computed tomography and ultrasonic testing, are often limited by geometry, material, accessibility, and cost, while in situ monitoring is not yet sufficiently mature to replace post-process inspection.

This dissertation establishes the Frequency Domain Assurance Criterion (FDAC) as a quantitative, vibration-based framework for defect detection in AM components. FDAC captures spatial–spectral correlations …

Mapping Historical Neighborhoods With Geospatial Viewshed Buffers, James B. Townsend

Dissertations, Master's Theses and Master's Reports

The concept of neighborhood has been long studied with little agreement beyond the notion that neighborhoods are somewhat self-contained areas within a wider urban environment. Despite the lack of a finite definition, there is wide agreement of the importance of studying population dynamics at the neighborhood scale. Many attempts have been made to spatially define, measure, and quantify contemporary neighborhoods, but less attention has been given to methods to spatially define historical neighborhoods. In this paper, we utilize a historical spatial data infrastructure for the city of London, Ontario to develop a viewshed methodology that recognizes that ‘neighborhood’ is unique …

The Excess Path Length Distribution: A Stochastic Model For Sample-Based Path Planners, Chaz B. Cornwall

Dissertations, Master's Theses and Master's Reports

Through random sampling, sample-based path planners enable autonomous agents to quickly find paths without human intervention. However, due to the paths' randomness, sample-based path planners currently require additional verification, partially nullifying agents' ability to act autonomously. I set out to characterize this uncertainty so humans know what to expect from these path planners and know how to alter the path planner to desired specifications. To ensure the results are theoretical as well as practical, I first create a stochastic model of path length uncertainty using the trade-off between sampling time and optimality. By leveraging this model, my proposed algorithm reduces …

Modeling Determinants Of Significant Noncompliance In The U.S. Mining Sector: A Fixed Effects Logistic Regression Approach, Eli Johnson

Dissertations, Master's Theses and Master's Reports

This study examines environmental compliance behavior among mining facilities regulated under the U.S. Clean Water Act (CWA). Using a national quarterly panel of National Pollutant Discharge Elimination System (NPDES)-permitted mining facilities, the analysis evaluates whether local socioeconomic and demographic indicators are associated with the likelihood that a facility enters significant noncompliance (SNC) status. Facility compliance histories are compiled from the U.S. Environmental Protection Agency’s Enforcement and Compliance History Online (ECHO) database and is merged with county- and state-level socioeconomic indicators and election data. A fixed-effects logistic regression model is used to account for time-invariant facility heterogeneity. The results suggest that …

Microgravity-Induced Alterations In Left Atrial Hemodynamics And Thrombogenic Risk: Insights From Healthy And Atrial Fibrillation Models, Grace M. Hoeppner

Dissertations, Master's Theses and Master's Reports

Background: Microgravity exposure alters cardiovascular loading, yet its impact on left atrial flow dynamics and thrombotic risk remains poorly understood. This study investigates how spaceflight-relevant microgravity-induced changes in cardiac outflow affect left atrial hemodynamics in healthy individuals and patients with atrial fibrillation.

Methods: Patient-specific left atrial models were generated for three healthy individuals and three AF patients. Computational fluid dynamics (CFD) simulations were performed using each patient’s baseline mitral outflow waveform and two modified waveforms representing short- and long-duration post-flight cardiac loading changes derived from echocardiographic observations. Hemodynamic metrics included left atrial velocity, time averaged wall shear stress, oscillatory shear …

Shm For Incipient Buckling Detection In Overloaded Structures Using Nonlinear System Identification Algorithms On Redundant Data Sets, Padmanabh Shridhar Desai

Dissertations, Master's Theses and Master's Reports

Structural health monitoring (SHM) detects and characterizes damage to predict failure, but failures such as buckling, which are not predicated on traditional damage modalities, are harder to detect. Direct load measurements are costly and difficult to implement (especially for dead loads) as they require copious numbers of sensors, which must be installed before loading is present. Vibration-based detection is a good alternative because it can infer global structural characteristics with relatively few sensors. This dissertation presents an SHM approach for detecting incipient buckling in structures under excessive loads based on non-linear models fit from measurements of small lateral vibrations due …

Development And Calibration Of A 2-D Diesel Oxidation Catalyst Filter (Docf) Model With Spatially Varying Washcoats Using Spacims And Engine Loading Data, Thomas K. Price

Dissertations, Master's Theses and Master's Reports

Diesel engine exhaust contains regulated species, including carbon monoxide, hydrocarbons, nitrogen oxides, and particulate matter (PM). Meeting increasingly stringent emission standards typically requires multiple aftertreatment components, motivating the development of multifunctional devices that reduce system size, cost, and catalyst usage. Computational models are essential for guiding this design process; however, existing models primarily focus on single-function devices and rarely capture the behavior of multifunctional systems with multiple catalyst washcoats. This work presents a physics-based model of a wall-flow diesel oxidation catalyst filter (DOCF), a multifunctional device that integrates the roles of a diesel oxidation catalyst and a diesel particulate filter …

On The Vibrational Dynamics Of Wind Turbine Blades: The Oscillatory Response To Gust Pulses, And The Physical Mechanisms Behind Them, North A. Yates

Dissertations, Master's Theses and Master's Reports

An easily noticed trend in the utility-scale wind turbine industry is that the size of the machines has continued to increase over time. While this may have benefits in terms of increasing the power generation for a single turbine, a major drawback is the rate with which the weight of the turbine blades grow. To ensure these larger machines can be utilized, efforts are being put forth to create lighter blades. This may fix the weight issue, but brings on a new one; these lighter blades can also be more flexible than previously studied ones. It is, therefore, vitally important …

Modeling And Testing Chain Trencher Excavator And Cone Penetrometer Robotic Prospecting Systems For Lunar In-Situ Resource Utilization, Marcello C. Guadagno

Dissertations, Master's Theses and Master's Reports

The Artemis Missions aim to establish a sustained human presence on the Moon, requiring In-Situ Resource Utilization (ISRU) of water-ice deposits in permanently shadowed regions. Two critical capabilities must be developed to enable ISRU at scale: prospecting instruments that can characterize the spatial distribution and geotechnical properties of icy regolith in situ, and excavation systems that can extract hardened icy regolith efficiently. This dissertation addresses both needs through the development and testing of a Percussive Heated Cone Penetrometer (PHCP) for geotechnical prospecting and a chain trencher excavator for icy regolith mining.

The PHCP was developed across eight design iterations and …