Digital Commons Network^™

Leveraging High-Performance Cloud Computing To Model Underwater Acoustic Propagation And Scattering From Time-Evolving Rough Sea-Surfaces Using The Finite-Difference Time-Domain Method, James Alexander Higgins

Dissertations and Theses

This dissertation presents a two-dimensional (2D) Finite-difference Time-domain (FDTD) model for simulating underwater acoustic propagation and scattering from a one-dimensional (1D) time-evolving rough sea-surface. The techniques discussed are extendable to three spatial dimensions. Traditional acoustic modeling techniques often rely on a "frozen" sea-surface assumption, which proves inadequate for long-duration signals interacting with the time-evolving boundary at many different wave height displacements during its transit. To address this, a new FDTD update equation incorporating a variable subgrid is developed, significantly enhancing spatial accuracy at the boundary without increasing computational cost or compromising stability.

The model's accuracy is rigorously validated against established …

Puf-Based Digital Money With Propagation-Of-Provenance And Offline Transfers Between Two Parties, Benjamin Bean, Cyrus Minwalla, Eirini Eleni Tsiropoulou, Jim Plusquellic

Electrical and Computer Engineering ETDs

Building on prior concepts of electronic money (eCash), we introduce a digital currency where a physical unclonable function (PUF) engenders devices with the twin properties of being verifiably enrolled as a member of a legitimate set of eCash devices and possessing of a hardware-based root-of-trust. A hardware-obfuscated secure enclave (HOSE) is proposed as a means of enabling a PUF-based propagation-of-provenance (POP) mechanism, which allows eCash tokens (eCt) to be securely signed and validated by recipients without incurring any third party dependencies at transfer time. The POP scheme establishes a chain of custody starting with token creation, extending through multiple bilateral …

Characterizing Temperature-Dependent Properties Of Fat For Improving High Intensity Focused Ultrasound Simulations, Brian Easthope

Theses and Dissertations

High-intensity focused ultrasound (HIFU) is a non-invasive therapeutic technique that relies on the precise delivery of acoustic energy to ablate diseased tissue. The presence of subcutaneous fat can significantly alter focal accuracy and treatment efficiency due to its distinct thermal and acoustic behavior. This study characterized the temperature-dependent thermal conductivity, thermal diffusivity, specific heat capacity, acoustic attenuation, and acoustic velocity of human subcutaneous fat to improve pretreatment modeling for HIFU therapies. Measurements were performed using a dual needle probe for thermal conductivity and diffusivity, differential scanning calorimetry for specific heat capacity, radiation force balance for attenuation, and through-transmission methods for …

2d-Nanosilicate Carriers For Sustained Delivery Of Vaccine Components, Chih Yun Liu

McKelvey School of Engineering Graduate Student Theses & Dissertations

Laponite® 2D Nanosilicates (NS) are disc-shaped platelets (~30 nm diameter, ~1 nm thick) with positively charged edges and negatively charged faces, capable of loading proteins, drugs, and nucleic acids via electrostatic interactions to form a house-of-cards gel that sequesters cargo. Here, we evaluated NS for sustained delivery of antigens and Toll-like receptor (TLR) agonists to extend germinal center duration and enhance antibody quality. The model antigen ovalbumin (OVA) was adsorbed onto NS at acidic pH in a ~1:1 ratio, with partial unfolding that remained stable at physiological pH. NS-OVA complexes were efficiently internalized by dendritic cells, with uptake driven primarily …

Automated Spectrum Analysis And Radionuclide Identification For Robot-Based Gamma Probes, Kennedy Ochieng Mengoh Alila

UNLV Theses, Dissertations, Professional Papers, and Capstones

Gamma spectroscopy is a technique used for the detection and identification of nuclear materials. Gamma-ray emission by radio nuclides is detected using scintillation detectors or semiconductor detectors such as NaI and CZT. Robot-based gamma probes enable radiation measurements in large areas and hard-to-reach cluttered hazardous environments, which significantly reduces radiation risks to personnel. The robotic probes require automated on-board gamma spectrum analysis and capabilities with platforms (unmanned aerial vehicles and unmanned ground vehicle systems) which use Robot Operating System (ROS). The aim of this thesis was to develop a method of an automated spectral analysis and isotope identification for robot-based …

Computational Study Of Cavitation In An Inducer Pump, Jaylen Leonard

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cavitation is ubiquitous in liquid-handling turbomachines. Cavitation bubbles form when the local pressure drops below a fluid’s vapor pressure, and their subsequent collapse causes implosions that generate shockwaves and microjets. These effects lead to fluid instability and structural damage to the blades and casing in turbomachines. This thesis investigates this cavitation phenomenon in turbomachines using Computational Fluid Dynamics (CFD). The cavitation model built in ANSYS Fluent® is first validated in a venturi tube model and then applied to an inducer pump. The geometry of the pump is derived from the Space Shuttle Main Engine (SSME) Low Pressure Oxidizer Pump (LPOP) …

Quantifying Biocrust Evaporation In Arid Lands By Combining Thermal Imaging And Lysimeter Measurements, Rebekah C. Magness

UNLV Theses, Dissertations, Professional Papers, and Capstones

Biological soil crusts (biocrusts) are miniature ecosystems of living organisms incorporated within the soil matrix and established in the topmost millimeters of the soil surface. Biocrust plays a critical role in the hydrologic processes in arid lands, yet the extent to which it increases or decreases evaporation remains unclear. To gain a better understanding of the impact of biocrust on evaporation compared to bare soil, I studied a cyanobacteria-dominated biocrust patch surrounded by bare soil atop a lysimeter in the Mojave Desert near Las Vegas, Nevada. Using high-resolution thermal imaging, and the known latent heat flux from the lysimeter, I …

Design And Development Of Biomimetic Hydrogel Interfaces For Enhanced Bioelectrical Signal Acquisition, Daniela Nikoloska

UNLV Theses, Dissertations, Professional Papers, and Capstones

Every second, human skin processes over one million sensory signals while maintaining properties such as electrical conductivity, mechanical adaptability, and regenerative capability that surpass all synthetic materials. Contemporary bioelectronic devices prove inadequate when contacting skin surfaces due to poor adhesion and electrical contact issues that prevent effective sensing. Despite advancements in wearable and bioelectronic technologies, current devices face major drawbacks when interfacing with human skin, particularly in maintaining firm adhesion, conformability, and low-noise electrical signal acquisition.

This research focuses on the development of a biomimetic hydrogel-based interface for bioelectronic sensing. Specifically, a hybrid hydrogel system composed of polydopamine (PDA)- doped …

Quantum Sensing Of Magnetic And Thermal Fields Using Nitrogen-Vacancy Centers On Spoof Surface Plasmon Waveguides, Maxwell Stonham

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nitrogen-vacancy (NV) centers in nanodiamonds are solid-state quantum defects capable of detecting magnetic fields and temperature at the nanoscale with high spatial resolution and optical addressability at room temperature. Their spin-dependent fluorescence enables optically detected magnetic resonance (ODMR), a technique widely used for quantum sensing. However, enhancing optical readout efficiency remains a critical challenge for scalable integration and various methods can be used to improve this.

This thesis explores a hybrid quantum sensing platform that integrates NV-based sensing with spoof surface plasmon waveguides designed to enhance optical excitation and emission efficiency through localized spoof plasmon modes supported by subwavelength corrugated …

Modeling The Mojave: A Multiphase, Mixed Methods Phenomenological Investigation Of Novice Understanding Of A Complex Ecological System, Nicole Juliana Thomas

UNLV Theses, Dissertations, Professional Papers, and Capstones

This research explores early college science majors’ conceptions of the Mojave Desert ecosystem as a complex system. A multi-level, explanatory sequential mixed methods design was employed to study college science majors’ understanding of the Mojave Desert ecosystem to better inform science pedagogy. The first level, the quantitative phase of the study, consisted of developing a mathematical representation of twelve ecosystem variables present within the Mojave Desert. The second level, the qualitative phase of the study, consisted of phenomenological semi-structured interviews with 23 early college science majors. The findings of this research suggest that the Mojave Desert operates as a complex, …

Inelastic Behavior Of Three-Story Buildings With Concrete-Filled Composite Plate Shear Walls Subjected To Wind Loads, Joshua John Blom

Theses and Dissertations

Although elastic design of the main wind force resisting system in a building is the conventional approach it is not always desirable. In this study, nonlinear static and dynamic analyses are used to predict the inelastic behavior of a three-story building with concrete-filled composite plate shear walls subjected to wind loads. To explore the potential for inelastic design, two types of planar composite shear wall buildings are examined: individual shear walls designed using an elastic approach, and coupled shear wall pairs designed using an inelastic approach adopted from seismic design provisions. Nonlinear static "pushover" analyses are run using an assumed …

Experimental Testing Of Axially Loaded Fuse Plates Without Continuous Buckling Restraint, Rebekah Elizabeth Higgins

Theses and Dissertations

Current seismic design practice is to design structures to avoid collapse and protect life. Buildings are designed to resist seismic loading through strength and ductility. In moment frames, this ductility traditionally comes from inelastic deformation of beams. Moment frame connections move inelastic deformation away from the column and allow a plastic hinge to form in the beam. This plastic hinge prevents collapse but leaves the building difficult to repair. Some proprietary moment frame connections address this issue with replaceable fuse plate connections. These fuse plate connections move the plastic hinge out of the beam and into the replaceable fuse, allowing …

Applied Research In Field Crop Pathology For Indiana, 2021, Darcy E. P. Telenko, Sujoung Shim

Purdue University Press Books

Applied Research in Field Crop Pathology for Indiana, 2021 serves as a summary of the applied field crop pathology research trials conducted in 2021 under the direction of the Purdue Field Crop Pathology program in the Department of Botany and Plant Pathology at Purdue University. In Indiana, there are more than 57,600 farms, 16,000 crop producers, and 900 certified crop advisers, Extension educators, and crop-protection industry representatives who manage more than 11.4 million crop-production acres with a total value of $6.3 billion annually. There are more than twenty diseases affecting corn, soybeans, and wheat that may decrease crop production and …

Ankimedbench: Evaluating Hierarchical Medical Knowledge In Language Model Embeddings, Neel Patel

UNLV Theses, Dissertations, Professional Papers, and Capstones

Despite achieving over 90% accuracy on medical benchmarks, recent studies show physicians cannot effectively leverage language models to improve clinical reasoning. Current benchmarks test isolated factual recall, but clinical practice requires hierarchical navigation through diagnostic categories—starting broad and narrowing systematically from chest pain to cardiovascular pathology to myocardial infarction to specific STEMI types. Existing evaluations cannot measure whether models preserve this taxonomic structure essential for clinical reasoning.

We introduce AnkiMedBench, built from 16,512 medical flashcards used by students preparing for licensing exams. Cards are organized across six hierarchy levels spanning 16 broad medical specialties to 672 specific diseases and conditions. …

Measuring And Modeling Nonlinear Vibrations In Structures With Mechanical Joints, Suzanna Gilbert

Theses and Dissertations

Many assembled structures have bolted or riveted joints. Aside from providing a convenient method of assembly, mechanical joints have an important effect on the structure's dynamic response to its environment. Friction and microslip within the joints help to damp out unwanted vibration. However, the joints also introduce nonlinearity into the response. Most notably, the natural vibrational modes of the structure no longer have constant natural frequencies and damping ratios. Rather, they shift as a function of vibration amplitude. Several methods exist to characterize the dynamics of nonlinear systems, yet they are generally validated on simple benchmark structures, and many still …

Empowering Wireless Mesh Uav Networks Through Software-Defined Networking, Hieu Quang

Electrical and Computer Engineering ETDs

Unmanned Aerial Vehicles (UAVs) have been widely deployed in applications such as environmental monitoring, disaster response, and surveillance. Effective coordination between UAVs depends on low-latency inter-UAV communication to exchange state information, decisions, and other critical data. UAV networks are inherently dynamic which necessitates a framework capable of handling scenarios such as traffic re-routing, and resilience to communication failures. To address the challenges of managing dynamic UAV networks, this thesis proposes a dual network approach composed of three main components. First, the Better Approach to Mobile Ad-hoc Networking (BATMAN) protocol is used to enable communication among UAVs. Second, the OpenFlow protocol …

“Bridging The Gap To Midwave Infrared Event-Based Sensors: Design, Sensitivity, And Radiation-Hardness Characterization Of A Single-Pixel Iii-V Event-Based Infrared Sensor For Space Applications, Zinah M. Alsaad

Electrical and Computer Engineering ETDs

Event-based sensing presents a revolutionary paradigm shift for next-generation space surveillance systems, where power consumption is an ever-worsening constraint as temporal resolution demands increase. In addition to reduced power consumption, low latency, and wide dynamic range, the event-based sensor fundamentally only produces data when there is a change in illumination from which events are generated; no data is produced if the scene remains static. With their event-based datastream being inherently focused on the dynamic information of the scene, they are particularly well-suited to machine vision and autonomous sensing applications. While these sensors have many compelling advantages, there are presently no …

Emulation Of Orbital Dynamics And Control Of Fully Actuated Seven-Axis Prismatic Joint Systems, Bennett Russell

Electrical and Computer Engineering ETDs

This thesis details the system modeling, design, control, simulation, construction, and testing of a fully-actuated seven axis prismatic joint system created for the primary purpose of emulating on-orbit maintenance tasks. Additionally, it seeks to further research of space-based control schemas and investigate stiction as a case study with a mountable hybrid hinge system that emulates stiction. Controllers are evaluated under common limits and metrics, including time to escape, overshoot, mechanical work, and limit-exceedance counts. Comparisons span a PID baseline, deterministic MPC/MPPI, and a probabilistic POMDP policy. Results verify the emulator and hybrid hinge meet the intended design criteria and show …

A Bump Hunting Approach To Finding Interpretable Data Pockets, Tushar Ojha

Electrical and Computer Engineering ETDs

This dissertation approaches the problem of extracting simple interpretations from local regions of data. This is sometimes called bump hunting because the local regions of interest have a high concentration of a particular output value. This work develops a bump hunting method for discrete-valued tabular data where each bump is modeled by a rectangular region of the input data space so its rule-based description admits a simple logical interpretation that can inform decisions. This method is designed for labeled data where each input feature has a distinct meaning that may or may not be related to the output, and the …

Fedchae: Federated Learning With Client Clustering And Hybrid Adaptive Engagement, Chaeeun Park

Electrical and Computer Engineering ETDs

As machine learning adoption expands, data privacy concerns have grown significantly. Federated Learning (FL) addresses this challenge by allowing clients to train locally and share only their model parameters with the server. However, conventional FL methods such as FedAvg suffer from high communication overhead, as all clients must participate in every global round.

This paper proposes FedChae (Federated Learning with Client Clustering and Hybrid Adaptive Engagement) to balance communication efficiency and model accuracy. FedChae alternates between Grouping Rounds, where all clients perform clustering, and Conventional Rounds, where one client per cluster updates the model.

Simulations with 100 clients using Multi-class …

Application Of Bimetallic Transition Metal Oxides Electrocatalysts For Li-Co2 Batteries And Li-O2 Batteries, Jianda Wang

Chemical and Biological Engineering ETDs

Li-ion batteries are the dominant commercial rechargeable batteries nowadays, which are used in electronic devices and electrified transportation widely. However, undesirable energy density of Li-ion batteries prohibits them from meeting requirements of new generation electronic devices. Therefore, it is important to find more alternative electronic energy storage systems with higher capacity. Fortunately, Li-CO2 batteries, featured high capacity and ability to convert CO2, have become a promising candidate to replace Li-ion batteries. In addition, Li-O2 batteries also attract people’s attention due to their high energy density and low cost. However, Li-CO2 batteries and Li-O2 batteries both face challenges of terrible cycle …

Thermally Stable And Regenerable Catalysts For Alkane Dehydrogenation, Ryan Alcala

Chemical and Biological Engineering ETDs

Shale gas upgrading reactions have gained much interest since production dramatically increased around 2010. These reactions occur at high temperatures (600°C +) where undesired processes like sintering and/or coking often occur. It is of interest to use materials like ceria as a catalyst support in these alkane conversion reactions, but ceria is prone to losing active surface area through sintering. It is also of interest to understand the behavior of PtMn and PtZn intermetallics for propane dehydrogenation as they have been identified as some of the best catalysts by theory-based prediction in literature. This manuscript explores ways of utilizing ceria’s …

Simulation Of Stress Induced By Laser Heating Of Glass, Austin Marsh Schuberth

Mechanical Engineering ETDs

The purpose of this work is to create a method for accurately simulating the stresses due to heating from femtosecond laser pulses. Our work aims to calculate stress and strain in glass exposed to laser pulses used for laser welding. We simulate the effects of thermal heating, thermal expansion, and the viscoelasticity of glass for a single straight weld bead. The laser heating of K9 borosilicate glass was simulated using Finite Element Analysis (FEA). Thermal models developed by other researchers in earlier work were utilized in calculating the temperatures due to the laser exposure to the glass material. 2D simulations …

Non-Destructive Characterization Of Ion Irradiated Yttrium Hydride For Microreactor Applications, Ryan E. Pena

Nuclear Engineering ETDs

As energy demands increase, nuclear reactors, especially microreactors, become a promising energy source. These reactors run at high temperatures (>280°C), requiring moderators that can endure these environments. Yttrium hydride is a possible moderator, but little is known about the material’s phase stability and hydrogen retention under irradiation. Through the use of a gold ion beam, samples with stoichiometries ranging from 1.6 to 2.0 were irradiated and tested. Through Vickers hardness testing, a model was created showing a correlation between hydrogen content and hardness. Raman spectroscopy showed high temperature and irradiated samples have significant hydrogen loss. XRD quantified this hydrogen …

Sequential Low Dose Proton Irradiation And Nanomechanical Testing To Understand Mechanical And Microstructural Property Changes In Alloy 709, Abhishek Kc

Nuclear Engineering ETDs

Alloy 709, a 20Cr25Ni alloy, is an advanced austenitic steel designed for next generation sodium fast reactors. Preliminary studies have shown the potential of Alloy 709 in sodium fast reactors. In this study, Precipitate Treated Alloy 709 specimens are irradiated with 2 MeV H⁺ at 500 °C from 0.0057 dpa to 1.7 dpa. Electron microscopy characterization techniques are used to understand the effects of radiation on mechanical properties as well as microstructure of Alloy 709. The microstructure did not show formation of voids, amorphization of precipitates, or increase in grain size up to 1.7 dpa. Correspondingly nano-indentation and micro-pillar …

Coupled Adjoint-Based Perturbation Theory For Dynamics And Heat Transfer Multiphysics For Nuclear Transients, Alexis Maldonado

Nuclear Engineering ETDs

Nuclear reactor multiphysics modeling and simulation (M&S) enable advanced reactor design by analyzing how systems will react over time to various configurations, scenarios, and perturbations. However, high-fidelity coupled transient M&S for reactor cores are computationally expensive, making robust analyses challenging. This work develops a Coupled Adjoint-based Perturbation Theory for dynAmIcs and heat traNsfer (CAPTAIN) framework to rapidly quantify the impact of uncertainty to overall transient responses by generating sensitivity coefficients for temperature, power, and delayed neutron precursor concentrations using forward and adjoint solutions. This work presents an initial proof of principle, verified with direct perturbations to several inputs. Furthermore, this …

A Risk-Informed Approach To Performing The Pre-Closure Safety Analysis For The Deep Borehole Disposal Of Radioactive Waste, Jennifer Elizabeth Leute

Nuclear Engineering ETDs

Deep borehole disposal is an emerging concept which involves disposing of radioactive

waste in boreholes several kilometers deep then backfilling to minimize radionuclide

transport and distribute weight. Unfortunately, little documentation exists on borehole

safety case development, especially for pre-closure operations. This study aims to close

this gap by proposing a graded approach matrix based on consequence, maturity, and

complexity. Two case studies are used to demonstrate this application: Hanford CsCl

capsules and spent PWR assemblies. Simulations are used to predict potential for dose

exposure, revealing CsCl capsules have a much higher potential for being above the 5

rem public dose …

Parameter-Efficient Multimodal Adaptation: Ocr-Integrated Lora For Textvqa And Captioning, Karthik Ganesh Malini

Master's Theses

Vision-Language Models (VLMs) have emerged as transformative technologies for multimodal AI, yet they face significant hurdles in processing text-rich images required for enterprise applications like document understanding, medical imaging, and industrial inspection. Current VLMs struggle with accurate text extraction and reasoning, often exhibiting high hallucination rates and poor Optical Character Recognition (OCR) token utilization. To address these limitations, this research presents a comprehensive framework for optimizing parameter-efficient Low-Rank Adaptation (LoRA) fine-tuning strategies on state-of-the-art architectures, including LLaVA-1.5 and BLIVA-FlanT5. Our methodology integrates enhanced OCR token utilization, faithful caption generation, and specific hallucination mitigation techniques. We employ a multi-dimensional evaluation protocol …

Graph Based Planning With Guarantees, Trazon Tyrik Jimerson

Mechanical Engineering ETDs

This thesis presents two graph-based methods with formal guarantees for motion planning and routing. First, the invariant-set motion planner (ISMP), which uses constraint admissible positive invariant (CAPI) sets of closed-loop dynamics, is adapted for spacecraft attitude planning to avoid moving keep-out zones. Contributions include time bounds for maneuvers via exponential stability, a single-stage reachability graph from one-step backward reachable CAPI sets, and its multi-stage expansion to certify node safety over time. Simulations verify safe attitude control with moving obstacles. Second, we formulate a convex optimization problem over a network for evacuation planning with operational constraints such as helicopter capacity and …

Real-Time Frequency Tuning Of Kinetic Energy Harvesters Via System Mass Adjustment, Rahul Adhikari

Mechanical Engineering ETDs

This research presents a method for real-time frequency tuning of piezoelectric kinetic energy harvesters through system-mass adjustment. Custom 3D-printed proof masses with cavity arrays were used to redistribute solid or liquid mass, enabling controlled modification of resonant frequency. Experimental studies using microparticles and liquids—including water, silicone oil, and sodium polytungstate—demonstrated an achievable tuning range of 115.27 Hz with sub-hertz resolution (< 0.1 Hz), confirming precise and repeatable frequency control. Finite-element modeling guided design optimization, while a microfluidic channel system enabled automated liquid filling for real-time operation. A MATLAB-based EH_Tuning application was developed to visualize and predict frequency responses. The combined …