Engineering Commons^™

Instability Analysis In Cylindrical Thin Film–Compliant Core Structures: Numerical Simulations And Effects Of Inelastic Deformation, Md Al Rifat Anan

Mechanical Engineering ETDs

When a thin film bonded to a thick compliant substrate is subject to in-plane compression, wrinkles can develop if the critical state for instability is reached. In various applications the film/substrate system may also take the form of cylindrical fibers, where an axial compressive loading can trigger axisymmetric wrinkles. A straightforward computational approach to simulate such wrinkling behavior is needed for material design, to either prevent wrinkling or to exploit its benefits for flexible device applications. In this work a comprehensive numerical study is undertaken by employing the finite element method. The embedded imperfection approach used previously for planar structures …

Multiscale And Multi-Model Studies Of Metal Plasticity, Luo Li

Mechanical Engineering ETDs

Plastic deformation is the process in which the material deforms permanently due to external effects. Twinning and slip are two main mechanisms of plastic deformation in metallic materials. The prominent mechanism of plastic deformation in metals that have FCC crystal structures is slip or gliding movement of dislocations, which is mainly focused on here. In the current study, frameworks for investigating plasticity phenomena of metals at different scales ranging from microscale to macroscale are demonstrated. Specifically, the macroscale modeling of plastic response of metallic materials induced by indentations are emulated by nonlinear FEA simulations. Simulation results of macroscale modeling are …

Phase Nanoscopy With Correlated Frequency Combs, Xiaobing Zhu

Optical Science and Engineering ETDs

In this dissertation a sensing method applying to any physical quantity that modifies optical phase is developed. Two pulses are produced inside a synchronously pumped Optical Parametric Oscillator, generating two identical, undistinguishable frequency combs. The physical quantity to be measured applies a small phase shift/round trip to one of the pulses, resulting in a frequency shift of the corresponding comb. The latter frequency is measured as a beat by interfering the two combs on a detector. A world record resolution, close to the quantum limit, of 0.033 nanoradian (corresponding to 0.006 fm in displacement) is achieved. A detailed analysis of …

Understanding The Metallic And Oxide Phases In Platinum-Based Bimetallic Heterogeneous Catalysts After High-Temperature Oxidation, Stephen John Porter Jr

Nanoscience and Microsystems ETDs

Platinum (Pt) and palladium (Pd) are critical components in diesel emission control systems, enabling the conversion of harmful pollutants under demanding conditions. However, Pt’s effectiveness is hindered by sintering under high-temperature oxidizing environments. This dissertation investigates how Pt and Pd evolve under oxidizing conditions at 800°C, highlighting their distinct thermodynamic behaviors and interactions. Using TEM, EDS, EELS, XRF, XRD, and EXAFS, we show that Pd suppresses Pt sintering by reducing the volatility of PtO₂, leading to the formation of stable particles. Both Pt and Pd are present in metallic and oxide states, forming biphasic 'Janus' particles with conjoined metal and …

Improving Infiltration Model Performance In Arid And Urban Regions, Samuel Stephen Coulter

Civil Engineering ETDs

Flooding in arid regions is infrequent but damaging and limited historical data makes flood modeling an important tool for flood infrastructure design. This study improves flood modeling guidance by using plot-scale tests to determine the impact of slope, compaction, gravel mulch and landscape fabric on infiltration and runoff rates in sandy soil types. This data will be used as guidance for the linear and constant model. The performance of this model was compared with the curve number model for a hypothetical 100-year design storm. Results showed that gravel mulch increased infiltration rates by 66% and reduced erosion on steep and …

Advancements In Microarray Manufacturing Enable Emerging Technologies, Kendall Hoff

Biomedical Engineering ETDs

Significant advances in manufacturing technologies have enabled the production of new DNA microarrays for use in emergent technology. Photolithography, wafer scale manufacturing, and improvements in synthesis chemistry and design enable high-throughput production of extremely high-quality arrays. These new arrays offer extremely high oligonucleotide densities, in the range of tens of thousands of oligonucleotides per square micron. They also offer smaller features sizes, with millions of features per square centimeter. Furthermore, they can be manufactured with the DNA tethered at either end to the surface, leaving either the 5’ or 3’ end free and available for use in enzymatic reactions; and …

Theoretical And Experimental Investigation Of Liquid-Liquid Phase Separation: Characterizing Elastin-Like-Polypeptides, Adam D. Quintana

Chemical and Biological Engineering ETDs

This dissertation develops and validates a semi-empirical Flory–Huggins-based interaction model, combined with Cahn–Hilliard simulations, for predicting multi-component liquid–liquid phase separation (LLPS) in elastin-like polypeptide (ELP) systems. Equilibrium droplet compositions, measured using a PDMS-based microfluidic device, enabled direct parameterization of interaction coefficients. The model was applied to generate phase diagrams and assess composition dependence in ternary mixtures. Cahn–Hilliard simulations were conducted to explore potential phase morphologies under different interfacial conditions. Multi-component Lattice Boltzmann simulations were implemented to model droplet morphology evolution under varying interfacial and diffusive parameters, reproducing experimentally relevant morphologies. A three-phase wetting study revealed conditions for selective wetting and …

Upcycling Of Polydicyclopentadiene (Pdcpd) Via Dynamic Bonds, Catherine Biju

Biomedical Engineering ETDs

Thermoset polymers are valued for their exceptional mechanical strength and thermal stability, but suffer from irreversibility due to permanent covalent crosslinks, limiting recyclability. Polydicyclopentadiene (pDCPD), a widely used thermoset, exemplifies this limitation despite its excellent mechanical properties. In this study, we report an upcycling strategy for pDCPD through the incorporation of dynamic imine bonds. The successful integration of imine bonds was confirmed by ¹H NMR spectroscopy. Mechanical testing revealed that the modified pDCPD (pDCPD-imine) exhibits enhanced tensile strength and maintains its performance across multiple reprocessing cycles. Moreover, the dynamic nature of the imine bonds imparts healability to the network. This …

Flysurf: A Flying Robotic Surface With Shape Morphing And Motion Control, Kevin Aubert De Luchi Lomellini

Electrical and Computer Engineering ETDs

This thesis introduces FlySurf, a novel flying robotic surface capable of simultaneous shape morphing and motion control. FlySurf is modeled as a mesh-based dynamic structure actuated by multiple unmanned aerial vehicles, enabling complex deformations during flight. The proposed control architecture comprises three main components. First, a state estimator to infer the robotic surface state from limited observations. Second, a shape trajectory planner that incorporates an affine deformation term to preserve surface integrity during shape transitions. Third, a surface controller to minimize the error between the desired and actual surface configurations.

The methodology is validated through realistic simulations and hardware experiments, …

Pd-Based Hydrogen Separation Membranes Synthesized Via A Liquid-Phase Route, Chase W. Thompson

Chemical and Biological Engineering ETDs

Palladium (Pd) membranes have gained significant attention for their ability to selectively separate hydrogen, a critical process for clean energy applications such as fuel cells and hydrogen storage. However, challenges such as grain growth, sintering, hydrogen embrittlement, and film uniformity limit their scalability and long-term stability. This thesis focuses on the controlled synthesis, deposition, and stability of Pd nanoparticles to optimize membrane performance for hydrogen separation. This work investigates solution-phase synthesis of Pd nanoparticles, focusing on temperature, precursor concentration, and solvent composition as key variables influencing particle growth and dispersion. Pd membranes were fabricated using nanoparticle deposition onto porous supports, …

Investigating Vacuum Insulator Flashover Resistance Of Rexolite And Acrylic Before And After Applying Novel Insulator Cleaning Techniques, Ritin Joseph

Electrical and Computer Engineering ETDs

Pulsed power involves accumulating large amounts of electrical energy and releasing it instantaneously. Large pulsed power accelerators use a vacuum insulator stack to facilitate power transfer from the liquid to vacuum section. Limiting the probability of surface flashover in this setting to acceptable levels improves machine longevity and prevents energy loss. Post-shot debris deposition requires a refurbishment process to prevent deterioration of dielectric performance, though the current technique of hand-sanding is long, labor-intensive, and pose serious health hazards. I have collected flashover data on frustrum-shaped Acrylic and C-Lec Rexolite® (cross-linked polystyrene) samples using a 500-kV, 20-ns risetime pulsed power test …

Data-Driven Constrained Control, Ali Kashani

Mechanical Engineering ETDs

Ensuring safety is a fundamental challenge. Traditional methods often rely on precise mathematical models, which are difficult, impractical, or costly to obtain for real-world systems with complex, nonlinear dynamics. This dissertation develops direct data-driven control approaches that enable safe and efficient operation of nonlinear systems without requiring explicit models or performing system identification. This effort leverages machine learning, optimization, and control theory to bridge theoretical rigor and practical applicability. Deterministic guarantees are provided based on the Lipschitz continuity of the system, and probabilistic guarantees through scenario optimization. The computation of safe sets is performed using one-shot approaches with broad neural …

Ai-Driven Emi Mitigation For Smart Healthcare: Generative Adversarial Networks And Edge Computing For Reliable Medical Systems, Mona Esmaeili

Electrical and Computer Engineering ETDs

Electromagnetic interference (EMI) from radio frequency (RF) sources poses a major challenge to digital systems, especially in high-electromagnetic environments. Tradi- tional electromagnetic compatibility (EMC) analysis often focuses on continuous wave (CW) interference and overlooks the effects of waveform modulation on EMI coupling. This thesis explores how modulated waveforms influence EMI coupling and introduces a Generative Adversarial Network (GAN)-based classification framework to distinguish between harmful and non-harmful EMI signals. The study extends conventional EMC analysis using machine learning (ML), showing that modulated EMI waveforms can in- crease coupling by up to 27% compared to CW signals. This highlights the need for …

Development Of A Near Terahertz Backward Wave Oscillator Using Standard Waveguide, Alexander Glick

Electrical and Computer Engineering ETDs

There is a demand for terahertz (THz) frequency radiation sources. Applications include, but are not limited to, imaging for medical and security purposes, biochemical and organic spectroscopy, and velocimetry. Historically, there was a limited supply of THz devices due to technological limitations. In recent years much progress has been made to reduce this “gap” in supply and demand for THz sources. This work proposes a vacuum electronic device that produces high power, extremely high frequency radiation in the G-band, by utilizing a backward wave oscillator (BWO) based on WR3 standard waveguide. This device is compact, fundamentally simple, and has great …

Devices Related To Electrical Fast-Transient Protection And Detection, Cameron D. Harjes

Electrical and Computer Engineering ETDs

Electrical energy from natural occurring phenomena, such as an indirect lightning strike, can electromagnetically couple with nearby electronics thereby generating unwanted electrical fast-transients (EFT) signals in the circuit. Highly energetic EFT can interfere with a circuit’s normal operation or even destroy some circuit components entirely. Mitigating EFT has been a subject of research for decades and led to the development of devices such as lightning surge arresters (LSAs). These devices are critical for the protection of the electrical power grid from lightning induced EFT, however electromagnetic pulses (EMP) and other high-power radio frequency (RF) sources can generate much higher frequency …

Aerial Robotic Studies Of Volcanic Co2 Emissions, John Ericksen

Computer Science ETDs

Volcanic systems are inherently complex, involving dynamic interactions among magma flow, gas emissions, and atmospheric dispersion. This dissertation focuses on developing and analyzing autonomous UAS algorithms for efficiently surveying volcanic CO2 plumes, introducing several novel methods: the LoCUS algorithm, a swarm coordination and self-healing algorithm that supports gradient-based plume tracking, a transect-based technique that employs a 2D Gaussian fit to calculate CO2 plume flux, and the Sketch algorithm for rapid plume boundary tracing. By treating multiple UAS as a single scientific instrument, these methods leverage swarm algorithms to use in-situ data in ways impossible with individual drones. Validated through simulations …

Design Of A Subthreshold Cmos Inverter-Based Amplifier For Low-Noise And Low-Power Applications, Landon Alexander Schmucker

Electrical and Computer Engineering ETDs

Amplification is a fundamental function in most analog circuits. There is a fast-growing demand for low-power, low-noise, and high-gain amplifiers. Modern semiconductor processes are increasingly optimized for digital applications, which has introduced new challenges in analog design. To address these challenges, analog designers have investigated replacing conventional analog circuits with digital implementations. One promising application is the typical CMOS inverter as an amplifier.

This research presents a CMOS inverter-based amplifier with feedback designed to achieve low power consumption, low input noise, and high gain. Unlike typical CMOS inverter-based amplifiers, this topology has two distinctive features: (1) it uses a MOSFET …

Instability-Driven Phase Separation For Quantum Structure Formation In Iii-V Semiconductors, Leonid Miroshnik

Chemical and Biological Engineering ETDs

High temperature phase instability limits the performance of III-V zinc blende semiconductor devices. A technique using an encapsulant and sacrificial layer is developed to reduce thermal degradation by group V sublimation during thermal processing of InGaAs/GaAs structures. This technique is successful in preventing As sublimation and preserving an atomically smooth surface required for surface-sensitive characterization. The degradation of the GaAsSb/InP interface by phase separation is studied. Significant interdiffusion and intermixing occurs due to the formation of a molten InSb at the interface. The intermixing is driven by phase separation and melting of the InSb interfacial layer that enhances atomic mobility. …

Reconfiguration-Driven Assembly Of Inorganic Nanomembranes, Divya Jyoti Prakash

Chemical and Biological Engineering ETDs

This thesis focuses on the guided self-assembly of metastable nanomembranes (NMs) that are either amorphous or polycrystalline. Guided self-assembly of NMs is a robust and scalable method to obtain a variety of three-dimensional structures such as helices, rolled-up tubes, and networks of interconnected channels. These 3D structures have important applications as on-chip actuators, sensors, inductors, transformers, waveguides, and antennas. Furthermore, a large amount of strain and strain gradient can be imparted in NMs by bending them to a nanoscale and microscale radius of curvature, making guided self-assembly on NMs a viable route to extreme strain engineering of amorphous and polycrystalline …

Predictive Modeling Of Electro-Optic Modulators Under Electromagnetic Interference, Hasan Ahmed

Optical Science and Engineering ETDs

In this age of electronic warfare, directed energy research is of utmost importance to ensure national security, robust military defense systems and gain a competitive edge in research worldwide. This thesis explores the intentional directed energy impacts on electro-optic devices by developing analytical predictive models through experimental data validation. An electro-optic modulator known as Mach-Zehnder modulator (MZM) is used to understand the implications of intentional EMI. A low frequency RF signal is injected in the MZM to create an EMI environment. The MZM behavior changes due to EMI during a pseudo-random bit sequence signal modulation were studied through analyzing receiver …

Intelligent Crowdsourcing Based On Online Social Networks, Adedamola Adesokan

Electrical and Computer Engineering ETDs

The prevalence of Online Social Networks has completely changed how individuals communicate and cooperate. This dissertation explores the integration of intelligent crowdsourcing mechanisms into OSNs, focusing on game theory, reinforcement learn- ing, and social network dynamics to enhance the allocation of tasks, participation by users, and distribution of rewards. It proposes several models that utilize trust- based models, hedonic coalition games, and influencer dynamics for optimization of crowdsourcing. The major challenges to be addressed include task selection, reward distribution, and incentivizing participation, taking into consideration aspects re- lated to social influence, trust, and user engagement. The models so proposed have …

Navajo Speech Recognition Using Low-Resource Language Models, Emery M. Sutherland

Electrical and Computer Engineering ETDs

This thesis describes the development of a speech recognition system to classify Navajo (Dine) words using Low Resource Language (LRL) datasets. Presently there are no recognized high-quality open-sourced datasets for the Dine language needed to train models for speech recognition. A small balanced dataset was designed to train several models. To overcome the scarcity of the LRL dataset, the audio recordings were augmented to account for time-stretching, amplitude variations, time shifts, small amounts of white Gaussian noise, and SpecAugmentation. The models included a Recurrent Neural Network (RNN), a Convolutional Neural Network (CNN), and a Long Short-Term Memory (LSTM) model with …

Nanostructured Transition Metal Oxides For Electrochemical Co2 And Methane Conversion, Olumide O. Oladoyin

Chemical and Biological Engineering ETDs

Rising atmospheric CO₂ and CH₄ drive climate change, prompting research into their electrochemical conversion to valuable products. This study investigates electrodeposited nanostructured transition metal oxides (TMOs), unary (CuO, Co₃O₄) and dual (Cu-Co oxide) as catalysts for CO₂ reduction and CH₄ oxidation under ambient conditions. Fabricated on various substrates (Cu foil, SS316, carbon paper) and characterized by SEM, their electrochemical performance was evaluated via cyclic voltammetry.

Cu-Co oxide showed superior CO₂ reduction, leveraging the strengths of individual oxides. Co₃O₄ exhibited higher current densities for CH₄ oxidation, with SS316 proving the best substrate. Catalyst composition, morphology, and substrate significantly influenced efficiency. While …

Eyes On The Road: Disentagling Cyclist Mental Workload At Intersections, James Joseph Rawson

Civil Engineering ETDs

In North America, cyclists often share infrastructure with motor vehicles and encounter frequent conflicts with them at intersections. While past research assumes cyclists' experiences mirror those of drivers, most studies focus on roadway segments rather than intersections. This study addresses that gap by, for the first time we are aware of, examining cyclist perceptions at intersections using head and gaze movement data. Leveraging naturalistic data conducted in Albuquerque New Mexico, and statistical techniques, including t-test and repeated measures ANOVA, our findings suggest that – similar to drivers - cyclists do experience greater mental workload when performing turning movements than when …

Rf Emission From Partial Breakdown Events And Their Classification, Torin Sammeth

Electrical and Computer Engineering ETDs

Electrical breakdown is a core component of Pulse Power both in its utilization and as a failure point in systems. This research is investigating the feasibility of D-dot antennas to detect and potentially identify different forms of partial electrical breakdown in a point-to-plane gap geometry. In this work, the RF emission detected by a D-dot probe during a partial breakdown event is shown to correlate with the presence of light and current using a fast-current transformer and photomultiplier tube. Additionally, the frequency components of the RF signal were measured with the use of a fast Fourier transform. Identifying these frequencies …

Antenna Analysis Using Mixed Computer Platforms (Aacp), Keith H. Bova

Electrical and Computer Engineering ETDs

This thesis reviews the design, implementation, and benchmarking of commercially available, previous generation (CAPG) computer systems, and how they can be used with computational electromagnetics. The thesis focuses on their architecture, performance, and practical applications. It begins with an overview of CAPG system components, including different node types such as login/controllers, compute nodes, block storage, and object storage. The process of assembling these systems is outlined. The conjugate gradient method and direct linear solvers were benchmarked. The performance of CAPG systems is compared with modern computing architectures. A detailed analysis provides recommendations for designing CAPG systems around the performance of …

A Dynamically Efficient Predictive Controller For Voltage Stability In A Dc To Dc Boost Converter, Giovanni Reyna

Electrical and Computer Engineering ETDs

Reliable voltage regulation has become a critical issue with increase demand in modern power electronic applications. This study presents a Model Predictive Controller (MPC) for voltage regulation in DC-to-DC boost converters. A closed loop analytical MPC framework is created with the purpose of computing optimal duty cycles to maintain a stable output voltage under varying load conditions, input changes, and disturbances.

To evaluate the performance of the MPC we set the controller against a comparative analyzing with a traditional cascading proportional integral (PI) controller. The proposed controller design is specifically targeted to improve dynamic efficiency during the converter’s transient events. …

Cyber Physical Emulation Of Power Grids: Co-Simulation Of Exata Cps And Hypersim, Mckayla Snow

Electrical and Computer Engineering ETDs

This thesis explores the use of cyber-physical emulation of power grids to analyze the impact of different types of cyberattacks. It outlines the co-simulation process of HYPERSIM and EXata CPS within the OPAL-RT real-time digital simulator, demonstrating various cyberattacks on two power system models. The first model is a simple communication-focused testbed for easy demonstration of co-simulation setup, while the second is a power system model of a secondary network used to assess the cybersecurity of network protector units in low-voltage networks through a hardware-in-the-loop (HIL) testbed. Using this testbed, the cybersecurity of the direct transfer trip (DTT) scheme is …

Design And Characterization Of Radiation-Hardened Gaas Hbt-Based Optical Transceivers, Collin Burt

Electrical and Computer Engineering ETDs

Optical transceivers are desirable for their galvanic isolation and natural immunity to electromagnetic interference compared with direct electrical connections. This is true in normal operating environments as well as radiation environments. This work realizes and characterizes GaAs HBT-based optical transceivers across temperature and a range of radiation environments including high dose rate, total ionizing dose, neutron, and heavy ion. The transceiver designs are discussed and specific environmental design considerations are highlighted. Final results for each environment are provided and compared with existing transceivers.

Analytical Electrochemistry Of Nickel, Platinum, And Platinum-Nickel Electrodepositions, Kyle James Troche

Nanoscience and Microsystems ETDs

Nickel and platinum electrodeposits have numerous applications in corrosion and wear-resistant coatings, electronic connectors, heat resistance, metal finishings, and catalysts. The addition of additives can vastly change the morphology of the deposition. Electrokinetic parameters can be calculated by conducting rotating disk electrode (RDE) experiments along with Koutecky-Levich analysis. Significant challenges need to be addressed to deposit uniform films of Pt-Ni alloys from a single co-deposition bath. The main challenge is platinum’s catalytic property to reduce the overpotential for the hydrogen generation reaction. An Investigation into methanol and carbon monoxide’s hydrogen generation reaction suppression was conducted. Electrodeposition of nickel, platinum, and …