Physical Sciences and Mathematics Commons^™

Evaluation Of Regression Methods And Competition Indices In Characterizing Height-Diameter Relationships For Temperate And Pantropical Tree Species, Sakar Jha

Masters Theses

Height-diameter relationship models, denoted as H-D models, have important applications in sustainable forest management which include studying the vertical structure of a forest stand, understanding the habitat heterogeneity for wildlife niches, analyzing the growth rate pattern for making decisions regarding silvicultural treatments. Compared to monocultures, characterizing allometric relationships for uneven-aged, mixed-species forests, especially tropical forests, is more challenging and has historically received less attention. Modelling how the competitive interactions between trees of varying sizes and multiple species affects these relationships adds a high degree of complexity. In this study, five regression methods and five distance-independent competition indices were evaluated for …

Advancing Compact Modeling Of Electronic Devices: Machine Learning Approaches With Neural Networks, Mixture Density Networks, And Deep Symbolic Regression, Jack Robert Hutchins

Masters Theses

This thesis pioneers the integration of deep learning techniques into the realm of compact modeling, presenting three distinct approaches that enhance the precision, efficiency, and adaptability of compact models for electronic devices. The first method introduces a Generalized Multilayer Perception Compact Model, leveraging the function approximation capabilities of neural networks through a multilayer perception (MLP) framework. This approach utilizes hyperband tuning to optimize network hyperparameters, demonstrating its effectiveness on a HfOx memristor and establishing a versatile modeling strategy for both single-state and multistate devices.

The second approach explores the application of Mixture Density Networks (MDNs) to encapsulate the inherent stochasticity …

Understanding Student Experiences With Tls Client Authentication, Clay A. Shubert

Masters Theses

This thesis presents a comprehensive investigation into student experiences with TLS client authentication, highlighting the usability challenges and learning curves associated with this long term key managament system. We designed a study that required future innovators in technology and security to use modern-day implementations of this certificate-based authentication system. From this study, we analyzed server logs, project reports, and survey responses from students enrolled in the applied cryptography course. We revealed significant hurdles in the initial setup and long-term key management of credentials used in TLS client authentication, emphasizing the gap between theoretical knowledge and practical implementation skills. Through quantitative …

The Port Of San Diego's Maritime Clean Air Strategy: Enhancing Public Health With Innovative Clean Air Strategies, Gabriela Yamhure, Alexis Padilla

San Diego Regional Climate Collaborative

The Port of San Diego (The Port), established in 1962 under the Port act, is the Maritime agency that manages and stewards the thirty-four miles of coastal working waterfront along the San Diego Bay. The Port develops and promotes commerce, navigation, recreation, a healthy environment and fisheries around the San Diego Bay, contributes billions to San Diego’s economy, and is home to international cargo and trade operations. In a concerted effort to lessen greenhouse gas emissions impact of operations on local, often underserved communities, the Port developed and is implementing a Maritime Clean Air Strategy (MCAS), an update to the …

Fluorescent Lifetimes Of Oils And Oil Distillates In Artificial Seawater, Warren J. De Bruyn, Aaron Harrison, Emma Kocik, Dhivya Manickam, Ethan Truong, Catherine D. Clark

Chemistry Faculty and Staff Publications

Supporting data associated with a study of the fluorescent lifetimes of eleven oil and oil distillates in artificial seawater are given. The table is a list of the oil and oil distillate names along with the associated sample numbers used in this study and their API densities.

The excel data file contains lifetimes as a function of emission wavelength for different oils and oil products shown by sample number. The lifetimes were measured with a Horiba DeltaFlex Lifetime System that uses pulsed diode light sources. There is a separate sheet for each excitation source: 268, 285 and 348 nm. Lifetimes …

Non-Contact Wind Turbine Blade Crack Detection Using Laser Doppler Vibrometers, Ali Zabihi, Farhood Aghdasi, Chadi Ellouzi, Nand Kishore Singh, Ratneshwar Jha, Chen Shen

Henry M. Rowan College of Engineering Departmental Research

In response to the growing global demand for both energy and a clean environment, there has been an unprecedented rise in the utilization of renewable energy. Wind energy plays a crucial role in striving for carbon neutrality due to its eco-friendly characteristics. Despite its significance, wind energy infrastructure is susceptible to damage from various factors including wind or sea waves, rapidly changing environmental conditions, delamination, crack formation, and structural deterioration over time. This research focuses on investigating non-destructive testing (NDT) of wind turbine blades (WTBs) using approaches based on the vibration of the structures. To this end, WTBs are first …

Evaluation Of An End-To-End Radiotherapy Treatment Planning Pipeline For Prostate Cancer, Mohammad Daniel El Basha, Court Laurence, Carlos Eduardo Cardenas, Julianne Pollard-Larkin, Steven Frank, David T. Fuentes, Falk Poenisch, Zhiqian H. Yu

Dissertations & Theses (Open Access)

Radiation treatment planning is a crucial and time-intensive process in radiation therapy. This planning involves carefully designing a treatment regimen tailored to a patient’s specific condition, including the type, location, and size of the tumor with reference to surrounding healthy tissues. For prostate cancer, this tumor may be either local, locally advanced with extracapsular involvement, or extend into the pelvic lymph node chain. Automating essential parts of this process would allow for the rapid development of effective treatment plans and better plan optimization to enhance tumor control for better outcomes.

The first objective of this work, to automate the treatment …

Information Based Approach For Detecting Change Points In Inverse Gaussian Model With Applications, Alexis Anne Wallace

Electronic Theses, Projects, and Dissertations

Change point analysis is a method used to estimate the time point at which a change in the mean or variance of data occurs. It is widely used as changes appear in various datasets such as the stock market, temperature, and quality control, allowing statisticians to take appropriate measures to mitigate financial losses, operational disruptions, or other adverse impacts. In this thesis, we develop a change point detection procedure in the Inverse Gaussian (IG) model using the Modified Information Criterion (MIC). The IG distribution, originating as the distribution of the first passage time of Brownian motion with positive drift, offers …

Artificial Intelligence's Ability To Detect Online Predators, Olatilewa Osifeso

Electronic Theses, Projects, and Dissertations

Online child predators pose a danger to children who use the Internet. Children fall victim to online predators at an alarming rate, based on the data from the National Center of Missing and Exploited Children. When making online profiles and joining websites, you only need a name, an email and a password without identity verification. Studies have shown that online predators use a variety of methods and tools to manipulate and exploit children, such as blackmail, coercion, flattery, and deception. These issues have created an opportunity for skilled online predators to have fewer obstacles when it comes to contacting and …

Leveraging Blockchain Technology To Revamp The Vehicle Electrification Journey: Perspectives Of Accountability And Economic Circularity, Eva Escobar Brown

Electronic Theses, Projects, and Dissertations

The automotive industry is undergoing a significant transition accelerated by global emission regulations for a phase out of internal combustion engines (ICEs) and a transition toward the adoption of electric vehicles (EVs). While regulatory measures and incentivized adoption for EVs presents opportunities for reducing emissions and promoting sustainability, it also poses complex challenges. The EV industry faces potential production challenges, particularly in the sourcing, manufacturing, and lifecycle management of critical minerals and raw materials for electric vehicle batteries (EVBs). With a heavy reliance on a steady and diversified supply of critical minerals such as lithium, cobalt and rare earth elements, …

Crash Detecting System Using Deep Learning, Yogesh Reddy Muddam

Electronic Theses, Projects, and Dissertations

Accidents pose a significant risk to both individual and property safety, requiring effective detection and response systems. This work introduces an accident detection system using a convolutional neural network (CNN), which provides an impressive accuracy of 86.40%. Trained on diverse data sets of images and videos from various online sources, the model exhibits complex accident detection and classification and is known for its prowess in image classification and visualization.

CNN ensures better accident detection in various scenarios and road conditions. This example shows its adaptability to a real-world accident scenario and enhances its effectiveness in detecting early events. A key …

A Central Limit Theorem For The Number Of Excursion Set Components Of Gaussian Fields, Dmitry Beliaev, Michael Mcauley, Stephen Muirhead

Articles

For a smooth stationary Gaussian field f on R^d and level ℓ ∈ R, we consider the number of connected components of the excursion set {f ≥ ℓ} (or level set {f = ℓ}) contained in large domains. The mean of this quantity is known to scale like the volume of the domain under general assumptions on the field. We prove that, assuming sufficient decay of correlations (e.g. the Bargmann-Fock field), a central limit theorem holds with volume-order scaling. Previously such a result had only been established for ‘additive’ geometric functionals of the excursion/level sets (e.g. the volume or …

Sustainable Methodologies For Synthesis Of Small Organic Molecules Using Micellar Catalysis., Deborah Sam Ogulu

Electronic Theses and Dissertations

Organic synthesis is a critical process in the creation of small molecule pharmaceuticals and agrochemicals. However, most methods for synthesizing these small molecules rely on toxic organic solvents as the reaction medium which account for approximately 80% of pharmaceutical waste. Moreover, many catalytic reactions require expensive endangered precious metals like palladium and costly metals. This dissertation presents research that aims to develop sustainable, eco-friendly reaction conditions to address these issues. We developed a ligand-free bimetallic nanocatalyst for the hydrogenation of unsaturated enones. This ligand-free nanocatalyst was prepared from nickel and ppm loading of palladium and was stabilized by harnessing the …

Assessing Sustainability Within The Brewing Industry: A Literature Review And Benchmarking Analysis., Elijah Thomas Miller

Electronic Theses and Dissertations

The goals of this study were twofold: to further examine sustainability within the brewing industry through a literature analysis across four academic journals, and a benchmarking analysis of a Louisville, Kentucky brewery’s resource consumption and emissions production. Publications related to the brewing industry were examined for the presence of sustainability keywords: “efficiency, sustainability, carbon footprint, climate change and greenhouse gas”. Benchmarking examined the local brewery’s primary production facility to determine their performance compared to other surveyed breweries pursuing sustainability across the country. Literature examination found noticeable discrepancies between the appearance of sustainability topics within article abstracts and their discussion within …

Ligand-Stabilized Sno2 As A High-Performance And Scalable Electron Transport Material For Inverted Perovskite Solar Cells., Sashil Chapagain

Electronic Theses and Dissertations

Over the past decade, perovskite solar cell (PSC) technology has attracted significant attention for its low material costs, simple fabrication processes, and impressive photovoltaic performance, with recent power conversion efficiencies (PCEs) surpassing 26%. This advancement marks PSCs as strong competitors to traditional silicon-based photovoltaics. Despite the high efficiency of PSCs, the path to commercialization is hindered by challenges in stability, scalability, and module efficiency. The stability and scalability of PSCs are primarily dependent on the successive charge transfer layers (CTLs) that are interfaced with the perovskite layer. Among CTLs, metal oxide (MO_x) CTLs are preferred for their cost-effectiveness, …

Utilizing Metal Ligand Cooperativity To Activate Small Molecules., Christine Burgan

Electronic Theses and Dissertations

The problems created from the excessive use of fossil fuels can be approached from two directions: capture the CO₂ from the atmosphere or develop alternative energy sources. The current industrial standards for these are environmental and/or health hazards and utilize precious metals, respectively. Metal ligand cooperativity (MLC) has emerged as a promising alternative to using precious metals to activate small molecules. In this dissertation, we focus on a series of metal complexes based on the ligand diacetyl-2-(4-methyl-thiosemicarbazone)-3-(2-hydrazinopyridine) (H₂L¹) for either hydrogen evolution or CO₂ capture. The novel complexes were characterized by ¹H NMR, …

Mechanical And Thermal Measurement Techniques For Crystalline-Core/Crystalline-Clad Optical Fibers, Evan Watkins

All Theses

Optical fiber laser systems offer advantages such as high optical gain, efficient cooling, and the production of high-quality optical beams. Fiber lasers are characterized by their unique core-cladding structure, providing optical benefits and mechanical properties that impact their performance. Interests in materials such as yttrium aluminum garnets (YAG) and lutetium oxide (Lu2O3 also lutetia) as laser mediums are due to their high average power capabilities, but thermal management remains a challenge. This thesis discusses the choice of ytterbium (Yb3+) as a dopant in YAG and lutetia, exploring its electronic structure and relevance to thermal properties. The thesis focuses on the …

Multi-Script Handwriting Identification By Fragmenting Strokes, Joshua Jude Thomas

<strong> Theses and Dissertations </strong>

This study tests the effectiveness of Multi-Script Handwriting Identification after simplifying character strokes, by segmenting them into sub-parts. Character simplification is performed through splitting the character by branching-points and end-points, a process called stroke fragmentation in this study. The resulting sub-parts of the character are called stroke fragments and are evaluated individually to identify the writer. This process shares similarities with the concept of stroke decomposition in Optical Character Recognition which attempts to recognize characters through the writing strokes that make them up. The main idea of this study is that the characters of different writing‑scripts (English, Chinese, etc.) may …

Exploring The Relationship Between Anxiety And Virtual Reality Sickness, David Wesley Woolverton

<strong> Theses and Dissertations </strong>

As virtual reality (VR) becomes more commonly used in education, it is important to understand the technology’s weakness and mitigate any potential negative effects on student success. One adverse side-effect of VR use is simulation-induced motion sickness, known in the context of VR as VR sickness. Previous research by Howard and Van Zandt (2021) found that possessing a phobia had a significant positive correlation with VR sickness, but only if the phobia is triggered by the simulation, suggesting that symptoms are actually connected to the anxiety the phobia induces. This study explored the hypothesized correlation between anxiety and VR sickness, …

Geomagnetic Substorms Prediction Model Using Combined Physics-Based And Deep Learning Modeling Techniques, Ruthba Yasmin

<strong> Theses and Dissertations </strong>

This thesis aims to develop a hybrid physics-incorporated neural network model (PINN) for classifying geomangnetic substorms in Earth's Magnetosphere. The model is trained using a comprehensive list of substorm onsets, ground magentometer data from a global network, and solar wind parameters from the Advanced Composition Explorer (ACE) satellite. Two different neural network architectures are used, and the physics model used for training is called WINDMI. The magnetic field components on the ground, which are a function of the ionospheric currents, are captured by the SML index. The methodology involves using 60-minute data segments preceding an event to train the hybrid …

Bay Water Level Influences On Inundation And Morphological Changes Of A Semi-Connected Barrier Island During A Hurricane, Sydney D. Goodman

<strong> Theses and Dissertations </strong>

This research aims to identify flooding and erosion changes along a semi-connected barrier island system due to varying bay water levels during storm conditions. The numerical model XBeach is used to simulate Hurricane Michael conditions and the resulting inundation and morphological change near Tyndall Air Force Base (Tyndall AFB). The installation is located 12 miles southeast of Panama City Beach along the panhandle of Florida and is vulnerable to flooding due to its proximity to the Gulf of Mexico (GoM), Saint Andrew Sound and Saint Andrew Bay. A land bridge connects the barrier island to the mainland of Tyndall AFB …

Examining Outcomes Of Privacy Risk And Brand Trust On The Adoption Of Consumer Smart Devices, Marianne C. Loes

<strong> Theses and Dissertations </strong>

With more connected devices on earth than there are people, Internet of Things (IoT) is arguably just as innovative as the original introduction of the Internet. Though much of the research on technology acceptance and adoption has been conducted in organizational settings, the consumer use of IoT technologies, such as smart devices, is becoming a fertile field of research. The merger of these research streams is especially relevant from a societal perspective as smart devices become more embedded in consumer’s daily lives, particularly with the introduction of the “meta verse.” While original technology acceptance research is limited to two system-specific …

An Analysis Of Lyrical Repetition And Popularity In Popular Music Genres, Josh White

Undergraduate Honors Capstone Projects

This paper examines the correlation between repetitiveness and popularity in the genres of Christian, Country, EDM, Hip-Hop, Latin, Pop, R&B, and Rock. Repetitiveness is defined by the frequency of repeated words in lyrics, and the average number of streams per day defines popularity. This analysis also acknowledges the "popularity" metric provided by Spotify in calculating the correlation. To calculate this correlation, I wrote a program that accesses the Spotify and Genius APIs to gather metadata related to 76,069 songs from 1,246 artists, including data on repetitiveness, tempo, duration, and Spotify's audio metrics of "danceability," "energy," "speechiness," "acousticness," and "instrumentalness." I …

Next-Generation Crop Monitoring Technologies: Case Studies About Edge Image Processing For Crop Monitoring And Soil Water Property Modeling Via Above-Ground Sensors, Nipuna Chamara

Dissertations and Doctoral Documents from University of Nebraska-Lincoln, 2023–

Artificial Intelligence (AI) has advanced rapidly in the past two decades. Internet of Things (IoT) technology has advanced rapidly during the last decade. Merging these two technologies has immense potential in several industries, including agriculture.

We have identified several research gaps in utilizing IoT technology in agriculture. One problem was the digital divide between rural, unconnected, or limited connected areas and urban areas for utilizing images for decision-making, which has advanced with the growth of AI. Another area for improvement was the farmers' demotivation to use in-situ soil moisture sensors for irrigation decision-making due to inherited installation difficulties. As Nebraska …

Asteroidal Sets And Dominating Targets In Graphs, Oleksiy Al-Saadi

Dissertations and Doctoral Documents from University of Nebraska-Lincoln, 2023–

The focus of this Ph.D. thesis is on various distance and domination properties in graphs. In particular, we prove strong results about the interactions between asteroidal sets and dominating targets. Our results add to or extend a plethora of results on these properties within the literature. We define the class of strict dominating pair graphs and show structural and algorithmic properties of this class. Notably, we prove that such graphs have diameter 3, 4, or contain an asteroidal quadruple. Then, we design an algorithm to to efficiently recognize chordal hereditary dominating pair graphs. We provide new results that describe the …

First-Principles Studies Of Spin Transport And Spin-Orbit Torques, Giovanni Gabriel Báez Flores

Dissertations and Doctoral Documents from University of Nebraska-Lincoln, 2023–

This dissertation presents first-principles studies focusing on the effects of interfacial spin relaxation in metallic interfaces, interfacial intermixing on spin-orbit torques, and the effects of alloying on the transport properties of Fe|MgO|Fe magnetic tunnel junctions. Spin transport and spin-orbit torques are at the heart of phenomena in magnetic memory devices, such as tunnel magnetoresistance and magnetization switching. This work explores spin transport, spin-orbit coupling, spin-orbit torques, and tunneling magnetoresistance in a variety of materials and interfaces.

First discussed is the role of spin-orbit coupling at metallic interfaces by establishing a generalized magnetoelectronic circuit theory for normal metal (NM) interfaces, (NM|NM), …

Aggregate Games: Computations And Applications, Jared Soundy

Dissertations and Doctoral Documents from University of Nebraska-Lincoln, 2023–

Existing computational game theory studies consider compact representations of games that capture agent interaction in real-world environments and examine computation aspects of computing equilibrium concepts to analyze or predict agent behavior.

One of the most well-studied representations that capture many commonly studied real-world environments is aggregate games. Aggregate games, first systematically studied by Nobel laureate Reinhard Selten, have various applications in modeling the decision-making interdependence of agents, where each agent’s utility function depends on their own actions and the aggregations or summarizations of the actions of all agents. These applications include Cournot oligopoly competition, public good contribution, and voting, where …

Strong First Order Electroweak Phase Transitions In The Standard Model With A Real Scalar Singlet Extension, Anthony James Hooper

Dissertations and Doctoral Documents from University of Nebraska-Lincoln, 2023–

The large matter-antimatter asymmetry of the universe and whether the electroweak sector has always been broken are currently unanswered by the standard model (SM). One solution that addresses both these concerns is to impose a strong first order electroweak phase transition (SFOEWPT) and ensure electroweak baryogenesis occurs. Models that undergo a SFOEWPT in the early universe create bubbles of the true vacuum that expand until the universe reaches the vacuum expectation value measured today. If the phase transition is strong enough, then these bubbles may generate a detectable stochastic gravitational wave (GW).

However, the SM by itself can only perform …

From Bits To Beds: Design And Implementation Of A Hotel Booking System A Coding Project, Alexa Gilman

University Honors College

This thesis presents a comprehensive hotel booking system designed and implemented to showcase the transition "From Bits to Beds". There are two main motivations behind this project: firstly, to provide users with a user-friendly and efficient platform for booking accommodations. Secondly, it serves as a great learning opportunity, providing hands-on practice with coding, collaboration with teammates, and exposure to real-world challenges. The system utilizes technologies such as JavaScript, Express.js, and HTML/CSS to offer features like browsing hotels, filtering options, user authentication, and booking management. The implementation of this project demonstrates a successful integration of backend and frontend components, ensuring reliability …

Introduction To Nuclear Magnetic Resonance Spectroscopy In A Geochemical Setting, Evan Mack

University Honors College

Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical tool that is heavily employed in organic chemistry, but lacks use in geochemistry. The technique is most useful for characterization and structural analysis of analytes, but also sees use in kinetics analysis, speciation, and detection. This work aims to answer these questions regarding NMR spectroscopy’s use in geochemical settings: Which nuclei are studied? For what purposes is each nucleus studied? What affects the scope of the technique and has caused it to not be widely used? How often is NMR spectroscopy used? What trends are there in the technique’s use? The …