Digital Commons Network^™

A Stability Analysis Of The Phase-Lock Equations, Brian M. Sunguza

UNF Graduate Theses and Dissertations

Ginzburg and Landau have provided a set of equations that relate superconductivity to magnetic fields. Through a transformation process, Zhan has derived what are now called the phase-lock equations. A stability analysis of the spatially-independent phase-lock equations is the purpose of this presentation. This simplification is significant since it allowed for the analytical determination of equilibria, their stability, and the influence of a periodic forcing function. Through the use of an original code, numerical simulations are shown to corroborate the analytical results described above.

This analysis includes novel Lyapunov functions that allowed for the analytical determination of the instability region. …

Growth And Dielectric Characterization Of Epitaxial Sr1-Xmgxtio3 Thin Films, Richard Badu

UNF Graduate Theses and Dissertations

Complex oxide materials with ferroelectric ground states remain promising candi dates for next-generation high-capacitance and nonlinear microelectronic applica tions. One of those materials is SrTiO3 (STO). However, STO is an incipient fer roelectric with anomalously high dielectric permittivity at low temperatures. STO crystals possess a highly polarizable lattice that is sensitive to even small amounts of impurities. Substituting Mg into the STO matrix is predicted to induce a corre lation between ferroelectric and relaxor behavior. In this thesis, we demonstrated the growth of a series of epitaxial STO and Sr1-xMgxTiO3 thin films using molec ular beam epitaxy. The surface evolution …

Connecting The Existing Fiber Infrastructure To The Future With Antiresonant Hollow Core Fibers, Timothy Bate

Graduate Studies Theses and Dissertations 2026

Optical fiber systems based on solid-core silica waveguides underpin modern telecommunications, high-power laser delivery, precision sensing, and coherent optical systems. However, nonlinear effects, material absorption, and thermal limitations within silica increasingly constrain further scaling in both optical power and transmission performance. Antiresonant hollow-core fibers provide a promising alternative by guiding light predominantly in air, substantially reducing nonlinear interactions, latency, and optical damage while enabling transmission regimes inaccessible to conventional solid-core fibers. Despite rapid advances in antiresonant hollow-core fiber attenuation and power handling, one of the largest remaining barriers to widespread adoption is reliable integration with the existing solid-core fiber ecosystem. …

Design, Fabrication Modeling, And Optical Metrology Of Mwir Silicon Metalenses, Weiyu Chen

Graduate Studies Theses and Dissertations 2026

Mid-wave infrared (MWIR) optical systems require compact, broadband, manufacturable components whose performance can be predicted and measured reliably. Silicon metalenses are attractive because silicon combines high refractive index, MWIR transparency, and semiconductor-compatible fabrication. This dissertation develops a scale-bridging design–fabrication-modeling–metrology framework for MWIR silicon metalenses.

A shared full-aperture framework connects meta-atom libraries, physical layout generation, angular-spectrum propagation, point-spread-function calculation, and focal-plane energy metrics. Building on this foundation, the Dispersive Sweatt Model (DSM) incorporates meta-atom dispersion into conventional ray-tracing software, enabling broadband co-optimization of metasurfaces and refractive elements. A process-aware design framework then incorporates scanning electron microscopy (SEM)-measured height–radius relationships produced by …

Deciphering Ultrafast Photoinduced And Photocatalytic Reaction Dynamics On Oxide Surfaces: Direct Detection Of Radical Intermediates, Fragment Trapping, And Carbon–Carbon, Carbon–Oxygen, And Carbon–Hydrogen Bond Formation Pathways, Aakash Gupta

Graduate Studies Theses and Dissertations 2026

Understanding photoinduced reactions at solid interfaces is essential for advancing heterogeneous photocatalysis, surface photochemistry, and energy conversion technologies. This dissertation investigates the ultrafast dynamics of reactive intermediates, fragment trapping, and radical-mediated bond formation on oxide surfaces using time-of-flight mass spectrometry in conjunction with femtosecond pump-probe spectroscopy. Various experimental findings are validated through collaborations via density functional theory (DFT). By combining temporal, mass, and energy-resolved measurements, this work provides molecular-level insight into the elementary processes governing light-driven surface reactions. The photodissociation dynamics of CH₃I adsorbed on TiO₂(110), TiO₂(100), and amorphous silicon oxide surfaces are examined …

Integrated Optical Probes For Confocal Scanning Imaging And Adjustable Coherent-Gated Dynamic Sensing, Yonglin Huang

Graduate Studies Theses and Dissertations 2026

Optics and photonics have been one of the most important sciences and technologies that impact modern human life in a big way. For example, fiber-optics for communications and artificial intelligence. Optical probes are critical components for optical imaging and optical sensing technologies that have been actively researched and developed in the past decades. Advanced fiber-optic sensor probes with smaller size, better performance, lower noise, higher photon efficiency, rapid sensing time, and lower cost are needed in many applications, such as nanoscale material science, chemistry, and biomedical fields, etc.  In this project, new fiber-optic sensor probe technologies and integrated micro-optic devices …

Volumetric Fluorescence Microscopy For High-Throughput And High-Sensitivity Imaging: From Single Molecules To Tissues, Le-Mei Wang

Graduate Studies Theses and Dissertations 2026

Fluorescence microscopy is an indispensable tool in the biological sciences, enabling researchers to investigate intricate subcellular structures, particularly for volumetric studies. However, conventional optical microscopy for volumetric imaging remains fundamentally constrained by imaging speed and throughput. To bypass traditional serial z-scanning, we introduce an axially scan-free method using a phase layer cake to modulate the system's point spread function. This approach projects volumetric information onto a 2D plane in a single shot, offering high flexibility in tuning axial depth alongside simultaneous multicolor imaging with high spatial resolution and sensitivity. This dissertation divides these technical advancements into cellular and tissue imaging …

A Theoretical Study Of Molecular Photoionization: Applications To Molecules Of Astrophysical And Atmospheric Interest, Conner Penson

Graduate Studies Theses and Dissertations 2026

This thesis is devoted to the development of the model for total molecular photoionization spectra which is general to diatomic molecules and the application of this model to two benchmark systems, CH and N2, for verification. This model combines multi-channel quantum defect theory, first-principles ab initio molecular calculations, and vibrational frame transformation to accurately model molecular photoionization and electron impact including vibrational dynamics. The scattering data and transition dipole moments for the molecular systems were calculated using R-matrix method through the UKRMol+ codes. A vibrational frame transformation is then performed and multi-channel quantum defect theory is used to calculate closed …

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 …

Fully Differential Studies On Dissociative Capture In P + D2 Collisions And On Ionization In P + He Collisions, Shruti Majumdar

Doctoral Dissertations

Advancing our understanding of few-body dynamics in simple atomic systems is a fundamental objective in atomic scattering research. The underlying problem is that the Schrödinger equation is not analytically solvable for more than two mutually interacting particles. This involves a comprehensive exploration of various channels, such as ionization, capture, and excitation. A common theoretical approach to describe ion-atom collisions is based on perturbation theory, where the scattering amplitude is expanded in powers of the interaction potential. Here, understanding the few-body problem means accurately describing the relative importance of the higher- vs the first order terms.

In the case of ionization, …

Investigating The Effects Of Pressure On Fe And Co Intercalated 2h-Tas2 Through First-Principle Calculations, Ronald E. Putnam Jr.

UNF Graduate Theses and Dissertations

Using first-principles methods, we investigate the effects of applied isotropic pressure on the electronic and magnetic properties of intercalated Fe1/3TaS2 and Co1/3TaS2. Fe1/3TaS2 has been shown to be a ferromagnet that undergoes structural and magnetic phase transitions under applied pressure. The magnetic phase transitions are observed to be linked to the structural shift, and a mixture of magnetic phase states is present between 3 GPa and 6 GPa. Co1/3TaS2 was found to be antiferromagnetic, as confirmed by experimental work. One- and two-unit-cell systems of Co1/3TaS2 are analyzed, both showing band splitting that disappears under pressure. The application of pressure forces …

Real-Time Immersive Wildfire Simulation: A Game Engine Approach, Jake Bova

Graduate Student Theses, Dissertations, & Professional Papers

Wildfires are growing in frequency, size, and severity, placing escalating demands on firefighting resources and putting lives, property, and ecosystems at risk. Accurate prediction of fire behavior is critical to suppression planning, evacuation decisions, and firefighter training, yet the operational models that fire managers rely upon face a persistent tradeoff. High-fidelity physics-based models capture fire–atmosphere interactions faithfully but are computationally expensive, often running far slower than real time on CPU hardware, while faster empirical models sacrifice the dynamic coupling between a fire and the wind field it generates. Furthermore, most existing tools produce abstract, two-dimensional outputs that offer limited visual …

Temperature-Dependent Dielectric Function Of Solids From Coupled Oscillators With Radiation Reaction: Application To Atom–Surface Interactions, Tuhin Kanti Das

Doctoral Dissertations

In this dissertation, we propose a uniform functional form of the dielectric function of solids that is applicable over a wide range of frequencies. We apply our model to describe the dielectric function of two technologically important materials: silicon and calcium fluoride. The temperature dependence of their dielectric functions is also described using simple analytic forms. We found that a generalized Sellmeier-type model with complex denominators (“damped oscillators”) does not lead to a satisfactory fit of experimental data for the dielectric function. In contrast, our model, which is analytically only slightly more involved (“complex oscillator strengths”, complex numerators), allows us …

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 …

Gauge-Invariant Gravitational Wave Polarization In Metric F(R) Gravity With Cosmological Implications, Ramesh Radhakrishnan, David Mcnutt, Delaram Mirfendereski, Alejandro Pinero, Eric Davis, William Julius, Gerald Cleaver

Physics & Astronomy Faculty Publications

We develop a fully gauge-invariant analysis of gravitational-wave polarizations in metric 𝑓⁡(𝑅) gravity with a particular focus on the modified Starobinsky model 𝑓⁡(𝑅) =𝑅 +𝛼⁢𝑅2 −2⁢Λ, whose constant-curvature solution 𝑅𝑑 =4⁢Λ provides a natural de Sitter background for both early- and late-time cosmology. Linearizing the field equations around this background, we derive the Klein–Gordon equation for the curvature perturbation 𝛿⁢𝑅 and show that the scalar propagating mode acquires a mass 𝑚2𝜓 =1/(6⁢𝛼), highlighting how the same scalar degree of freedom governs inflationary dynamics at high curvature and the propagation of gravitational waves in the current accelerating Universe. Using the scalar–vector–tensor …

Investigating A Nanoparticle-Assisted Approach For Localized Strain Engineering In Two-Dimensional Materials, Skye Martichuski

Honors Theses and Capstones

This work investigated a fabrication strategy for inducing localized nanoscale deformation and strain in transferred MoS2 flakes using gold nanoparticle-coated substrates as a potential platform for strain engineering in two-dimensional materials. Substrate type, nanoparticle concentration, drying conditions, cleaning procedures, and flake transfer methods were investigated using optical microscopy and atomic force microscopy (AFM). Au-coated SiO2 substrates produced improved nanoparticle coverage compared to bare SiO2, while passive air drying yielded the most favorable nanoparticle distributions. Salt crystals introduced during passive drying were successfully removed with a gentle deionized water rinse, and a 50% diluted gold nanoparticle suspension provided improved particle spacing …

Gpu And Pso Accelerated Low-Latency Fully-Coherent All-Sky Search For Compact Binary Coalescences, Soumya D. Mohanty

Physics & Astronomy Faculty Publications

The fully-coherent all-sky (FCAS) search, which combines data from a gravitational wave detector network into a single likelihood function, is the preferred method prescribed by statistical theory for Gaussian noise. However, so far, its exorbitant computational cost has blocked its use for compact binary coalescence searches. We introduce a solution combining Particle Swarm Optimization with Graphics Processing Unit (GPU) acceleration that is ≈ 50-fold faster than real-time analysis. This transforms the prospect of a low-latency FCAS search on all GW data into a practical reality for the first time. With large-scale simulations enabled by this speedup, we examine the issue …

Efficient Search For Detection Candidates Using A Peak Finder Strategy For All-Sky-All-Frequency Gravitational Wave Radiometer, Arindam Sharma, Deepali Agarwal, Sanjit Mitra

Physics & Astronomy Faculty Publications

The first all-sky-all-frequency (ASAF) radiometer search was conducted using data from the first three observing runs of the Advanced LIGO and Advanced Virgo detectors. The significance of this search lies in its fast and unmodeled approach, leveraging a cross-correlation technique to identify common signals across the detector network. As a result, this method serves as an excellent alternative to search for unknown or poorly modeled continuous wave sources and narrow band components of the gravitational wave (GW) background. For continuous wave sources whose waveform can be modeled, this method can serve as the first stage of a hierarchical scheme by …

Hyena: An Observing System Simulation Experiment For Hypothetical Energetic Neutral Atom Imagers, Joel Tibbetts, Amy Keesee, Matina Gkioulidou, Robert Demajistre, Viacheslav Merkin

Faculty Publications

Mesoscale plasma sheet flows are widely understood to be a critical component of the overall picture of energy, particle, and magnetic flux transport during periods of geomagnetic activity. Without simultaneous measurements with true global coverage, the short lifetime (~10 min) and localized spatial extents (~1–3 R_E in azimuth) of these structures make obtaining a global picture of their contributions to stormtime magnetosphere dynamics difficult to characterize. Energetic neutral atom (ENA) imaging can enable remote mapping of plasma energization in the magnetosphere; however, its line-of-sight integrated nature, coupled with the challenging-to-characterize attributes of the target physical phenomena, means that numerous …

Charge Transport Modeling Of Multifunctional Molecular Transistors, Romena Akter

Graduate Studies Theses and Dissertations 2026

Distinguishing between the current–voltage characteristic curves associated with different transport mechanisms in a molecular electronic device and an artifact arising from device-level disorder is a central challenge in the study of molecular electronics. Characterizing these mechanisms and connecting them qualitatively to molecular-level orbital alignment, electrode coupling, voltage division, energetic disorder, and reorganization energy requires not only experimental data but also a rigorous theoretical framework for extracting physically meaningful parameters from measured transfer characteristics. This dissertation addresses this challenge in Chapters 2, 3, and 4 by developing and applying four complementary transport models —Simmons tunneling, single-level Landauer, Marcus hopping, and McConnell …

First-Principles Insights Into Electronic And Magnetic Structure At Hybrid Interfaces And Low-Dimensional Materials And Reaction On Surfaces, Bushra Ashraf

Graduate Studies Theses and Dissertations 2026

Low-dimensional materials and transition metal surfaces/interfaces provide complementary platforms for understanding how dimensionality, symmetry, spin–orbit coupling (SOC), and interfacial charge transfer/hybridization jointly control electronic structure, emergent magnetism, and surface reactivity. Using first-principles modeling with experimental comparisons, this work aims to establish interfacial structure–property relationships across low-dimensional systems.

Strained Pd adlayers on 2H-MoS₂(0001) provide a controlled platform to separate strain-driven exchange from interface-induced quenching in an itinerant d-electron metal. Although expansive strain promotes magnetism in free-standing Pd, strong Pd–MoS₂ hybridization and charge transfer suppress the monolayer moment and leave a narrow thickness window where magnetism re-emerges in …

Investigation Of Exotic Phenomena In Topological Quantum Materials, Iftakhar Bin Elius

Graduate Studies Theses and Dissertations 2026

he First Quantum Revolution established quantum mechanics as the foundation of modern physics, enabling transformative technologies such as semiconductors, lasers, and transistors through prin-ciples of quantization, wave-particle duality, and uncertainty. The ongoing Second Quantum Rev-olution harnesses entanglement, superposition, and coherence to advance quantum computation, communication, simulation, and sensing. Central to this endeavor is the study of quantum mate-rials hosting novel electronic structures and emergent phases, including topological insulators and Dirac, Weyl, and nodal-line semimetals. In this thesis, using angle-resolved photoemission spec-troscopy (ARPES), transport measurements, and density functional theory (DFT) calculations, we investigate three classes of materials: (i) magnetic topological semimetals, …

Detonability Limits Of Liquid Fuel Cloud, Khaoula Chougag

Graduate Studies Theses and Dissertations 2026

Detonation-based propulsion systems are of significant interest owing to their high thermodynamic efficiency, rapid energy release, and favorable entropy production relative to deflagration-based systems. Liquid fuels offer practical advantages in storage and volumetric energy density, making them attractive candidates for next-generation detonation engines. This dissertation investigates the detonability characteristics of liquid hydrocarbon fuel clouds through three interconnected studies conducted in a turbulent shock-tube environment using high-speed imaging and pressure diagnostics. The first study maps the detonability limits of monodisperse n-dodecane clouds by systematically varying droplet diameter (5-50 μm) and O₂/N₂ oxidizer composition at equivalence ratios spanning ϕ = 0.8-2.0. Results …

Detection And Discrimination Of Targets In Infrared Imagery, Adam T. Cuellar

Graduate Studies Theses and Dissertations 2026

Automated infrared (IR) imagery analysis is essential for persistent surveillance, defense, and security, yet it remains difficult when sensors move and when unknown objects appear. This dissertation addresses two fundamental problems: (1) detecting small moving targets amid platform-motion induced parallax and (2) distinguishing between known stationary targets and out-of-distribution (OOD) objects.   For detecting moving targets while the platform itself is in motion, auxiliary Global Positioning System and Inertial Navigation System data are combined with image analysis. Direction Cosine Matrices from calibrated inertial measurements enable sub-pixel frame alignment unattainable with purely image-based registration. The stabilized sequence is processed by a Reed–Xiaoli …

High-Efficiency And Compact Virtual Reality Displays, Zhenyi Luo

Graduate Studies Theses and Dissertations 2026

Virtual reality (VR) and augmented reality (AR) technologies are revolutionizing the way humans interact with digital information. However, current near-eye display systems still face critical challenges regarding optical efficiency, image quality, and device weight. This dissertation focuses on addressing these limitations through innovative liquid-crystal (LC) optics and system-level design strategies to achieve high-efficiency and compact VR displays.

First, to solve the longstanding problem of severe chromatic aberrations in ultrathin LC optics, I proposed an achromatic diffractive LC device. By stacking three LC layers with specifically designed spectral responses and polarization selectivity, I successfully reduced the chromatic aberrations. This idea enables …

High Intensity Ablation By Laser Filaments At Standoff Distances, Owen Thome

Graduate Studies Theses and Dissertations 2026

The high-power densities delivered to a target material by a laser allow for melting and vaporization to occur, a process called laser ablation. At higher intensities, plasma formation occurs and more complex material removal mechanisms take place. As laser power increases, nonlinear effects occur during propagation. One such effect, Kerr self-focusing, leads to beam collapse and ionization, resulting in a channel of plasma and region of high intensity light referred to as a laser filament. Filaments carry intensities on the order of 10¹³ W/cm² to significant distances without the use of large-scale focusing optics. Laser filament ablation is …

Advances In Active And Passive Integrated Photonic Devices On Thin-Film Lithium Niobate, Pooja S. Kulkarni

Graduate Studies Theses and Dissertations 2026

Thin-film lithium niobate (TFLN) has emerged as a powerful platform for integrated photonics, combining the exceptional electro-optic, nonlinear, and optical properties of bulk lithium niobate with the scalability and compactness of planar nanophotonic technologies. Building on these principles, advanced device architectures such as adiabatic dichroic filters have demonstrated exceptional spectral performance spanning over two octaves of bandwidth on the TFLN platform. Beyond reciprocal devices, it also offers promising pathways toward integrated nonreciprocal components. By leveraging broadband filtering structures and advanced nonlinear photonic design strategies, compact and monolithic optical isolators can be envisioned without relying on traditional magneto-optic materials. In the …

Physics-Informed Temperature Prediction Of Lithium-Ion Batteries Using Decomposition-Enhanced Lstm And Bilstm Models, Seyed Saeed Madani, Yasmin Shabeer, Michael Fowler, Satyam Panchal, Carlos Ziebert, Hicham Chaoui, François Allard

Electrical & Computer Engineering Faculty Publications

Accurately forecasting the operating temperature of lithium-ion batteries (LIBs) is essential for preventing thermal runaway, extending service life, and ensuring the safe operation of electric vehicles and stationary energy-storage systems. This work introduces a unified, physics-informed, and data-driven temperature-prediction framework that integrates mathematically governed preprocessing, electrothermal decomposition, and sequential deep learning architectures. The methodology systematically applies the governing relations to convert raw temperature measurements into trend, seasonal, and residual components, thereby isolating long-term thermal accumulation, reversible entropy-driven oscillations, and irreversible resistive heating. These physically interpretable signatures serve as structured inputs to machine learning and deep learning models trained on temporally …

Mtl_Tx: A Multi-Task Transformer Model For Improved Radiation Time-Series Estimation, Hongfang Zhang, Adam Stavola, Hal Ferguson, Bence Budavari, Hongyi Wu, Chiman Kwan, Jiang Li

Electrical & Computer Engineering Faculty Publications

Controlling radiation doses at potential radioactive facilities is critical to ensuring the safety of both personnel and the public. At the Thomas Jefferson National Accelerator Facility (JLab), multiple sensors are deployed around the three experimental halls to monitor key parameters, including single-beam current, energy levels, current leakage, and radiation values during accelerator operations. In this study, we developed a Multi-task Transformer model, MTL_TX, to accurately estimate radiation doses at sensor locations based on historical data, with the aim of enhancing safety in accelerator facilities and surrounding public areas. To improve estimation accuracy, we integrated two innovative components into the proposed …

Physics-Based Multi-Hazard Fragility Modeling Of Low-Rise Wood-Frame Buildings Under Hurricane-Induced Wind And Surge, Mumtasirun Nahar, Abdullah M. Braik, Mohammad Syed, Maria Koliou, Petros Sideris

Civil & Environmental Engineering Faculty Publications

Coastal buildings are exposed to concurrent hurricane-induced wind and storm surge, yet their vulnerability is commonly assessed using separate single-hazard models that neglect hazard interaction. This study developed a physics-based finite element framework to evaluate the performance of a low-rise light wood-frame building under simultaneous wind and surge-wave loading. A detailed three-dimensional model was constructed using a sub-assembly strategy that explicitly represented framing members, sheathing systems, and critical connections. Structural response was evaluated across a hazard space defined by wind speed, still-water depth, and flow velocity, and component- and system-level fragility functions were derived using Monte Carlo simulation and generalized …