Physical Sciences and Mathematics Commons^™

A New Proper Orthogonal Decomposition Method With Second Difference Quotients For The Wave Equation, Andrew Calvin Janes

Masters Theses

"Recently, researchers have investigated the relationship between proper orthogonal decomposition (POD), difference quotients (DQs), and pointwise in time error bounds for POD reduced order models of partial differential equations. In \cite {Sarahs}, a new approach to POD with DQs was developed that is more computationally efficient than the standard DQ POD approach and it also retains the guaranteed pointwise in time error bounds of the standard method. In this thesis, we extend the new DQ POD approach from \cite {Sarahs} to the case of second difference quotients (DDQs). Specifically, a new POD method utilizing DDQs and only one snapshot and …

The Geodetic Strain Rates From Gnss In The North American-Carribean-Cocos Triple Junction In Guatemala And Implications For Seismic Hazard, Tanaya Kashyap

Masters Theses

"Geodetic velocity data are pivotal for deciphering seismic risks, providing initial constraints for crustal surface strain rates. Gaining an understanding of the 2D surface strain tensor across an entire area necessitates knowledge of the surface velocity field, yet geodetic data such as measurements from the Global Navigation Satellite System (GNSS) are dispersed across the Earth’s surface. In the current scope of study, we have employed various methodologies to estimate strain rates in Guatemala, utilizing GNSS velocity data and leveraging the open-source Python tool Strain_2D. Strain_2D facilitates the computation of strain rates through diverse methods applied to the same dataset and …

Cryptographic Algorithms, Cryptocurrencies, And A Predictive Model Of Bitcoin Value By Pls Regression, Paul Kenneth O'Connor

Masters Theses

"With the invention of Bitcoin in 2009, as a seemingly timed response to the ongoing financial crisis, the popularity of the cryptocurrency has since continued to grow. Just this year, the Security Exchange Commission approved Bitcoin for exchange traded funds, allowing major investment firms to begin product trading. With this approval, and during this very moment of writing, Bitcoin has entered a bull market and reached a record value of over 72,000 USD. In addition, the Bitcoin halving event in April of 2024 is expected to increase demand even further. It has been anticipated that Bitcoin and other cryptocurrencies will …

Learn From The Past: Using Peer Data To Improve Course Recommendations In Personalized Education, Colton Walker

Masters Theses

"This work describes a recommendation approach designed to enhance student success by identifying semester schedules and graduation paths. The primary objective is to provide personalized graduation path recommendations rooted in individual student performance and draw insights from the academic journeys of similar students who successfully graduated. The original research contribution of this work lies in the development of a graduation path recommender system that leverages a combination of Markov Decision Process, Q-Learning, and collaborative filtering techniques to pinpoint graduation paths with a higher likelihood of leading students to success based on their academic progress thus far. The effectiveness of the …

Ltspice Modeling For Gan-Git Hemt Including Cryogenic Temperature, Md Maksudul Hossain, Yuqi Wei, H. Alan Mantooth

Electrical Engineering Faculty Publications and Presentations

Highly efficient electrically driven avionics have led to a renewed interest in cryogenic propulsion systems with the goal of reducing carbon emission footprint. Although cryogenic converters promise better efficiency and improved power density, the successful design is incumbent upon the appropriate switching device selection and simulation-based analyses prior to initial prototyping. In this work, a datasheet-driven compact model for a gallium nitride (GaN) Gate Injection Transistor (GIT) has been proposed and implemented in LTspice, a versatile, high performance, and free circuit simulator in order to investigate the merit of the chosen device in a power electronic system.

Impacts Of Wildfire On Subcanopy Energy Balance, Thermal Regime, And Permafrost Stability In Peat Plateaus At Scotty Creek, Canada, Maude Auclair

Theses and Dissertations (Comprehensive)

The stability of permafrost in peatland-dominated regions of northwestern Canada is compromised by ongoing climate warming and increased wildfire activity. This study examines an 8-year record of changes to the surface and subsurface properties of a peat plateau following a low-severity wildfire that occurred in 2014 in a region of thawing, discontinuous permafrost. This is accomplished by comparing the burned portion of a peat plateau to two unburned control sites, one of which is the unburned portion of the same plateau that was affected by the fire. Net radiation was not significantly different one year following the wildfire but became …

Incorporating Effects-Based Approaches Into Environmental Impact Assessment To Improve Post-Development Monitoring, Carolyn J M Brown

Theses and Dissertations (Comprehensive)

Over the last 50 years, improvements in design of industrial facilities have significantly reduced environmental impacts. But impacts still occur and monitoring programs are the main mechanism to inform when modification/implementation of mitigation is needed. Informed decisions require adequate baseline (pre-development) data to predict impacts based on the development’s design and to understand when the post-development environment has changed. An adaptive monitoring plan provides an effective way to evaluate monitoring results and allow for proactive responses to environmental change before impacts become difficult or challenging to reverse. Unfortunately, baseline data gathered during an environmental impact assessment (EIA) is often inadequate …

Multiscale Modelling Of Brain Networks And The Analysis Of Dynamic Processes In Neurodegenerative Disorders, Hina Shaheen

Theses and Dissertations (Comprehensive)

The complex nature of the human brain, with its intricate organic structure and multiscale spatio-temporal characteristics ranging from synapses to the entire brain, presents a major obstacle in brain modelling. Capturing this complexity poses a significant challenge for researchers. The complex interplay of coupled multiphysics and biochemical activities within this intricate system shapes the brain's capacity, functioning within a structure-function relationship that necessitates a specific mathematical framework. Advanced mathematical modelling approaches that incorporate the coupling of brain networks and the analysis of dynamic processes are essential for advancing therapeutic strategies aimed at treating neurodegenerative diseases (NDDs), which afflict millions of …

Geochemistry Of Rare Earth Elements In Simulated Natural Waters: Experiments And Modelling Of Precipitation, Complexation, And Bioavailability., Samantha Zulian

Theses and Dissertations (Comprehensive)

Rare earth elements (REEs) are an important part of modern technology and used for many applications. Mining, agriculture, improper recycling and medical applications can increase the concentration of these elements in surface waters. Metals in the environment including REEs can be found naturally but understanding the implications increase concentrations from anthropogenic inputs is important. REE mobility, persistence and toxicity is imperative to risk assessment as Canada begins to mine REE. Ultimately, as with other metals, the impacts of REEs in the environment should be dependent on the specific physical and chemical forms of the elements. Fractionation provides a practical method …

Coordination Chemistry Using Strategic Design Of Ligands For Switchable Properties, Delara Joekar

Theses and Dissertations (Comprehensive)

Coordination-driven self-assemblies are multifunctional molecular systems that provide an efficient method for miniaturization towards functional devices with diverse applications. Herein, the synthesis of novel pyrazole-based ligands suitable for construction of coordination assemblies is reported. These were designed using a strategy that incorporates the presence of both cationic and anionic coordination sites, and a third site for further functionalization. This design strategy has been used because there is still a knowledge gap for controlling the directionality of weak molecular forces in the presence of stronger competing forces. The structural characterization of these ligands, their Hirshfeld surface analysis, and select coordination complexes …

Last Passage Time And Excursion Theory For Solvable Diffusions With Applications In Mathematical Finance, Yaode Sui

Theses and Dissertations (Comprehensive)

In this dissertation, we investigate the properties of last passage times and excursion theory in one-dimensional solvable diffusions, emphasizing their applications in financial modeling, particularly in option pricing. We derive closed-form formulas for the marginal distribution of last passage times and their joint distribution with process values, including the maximum and minimum of the process value. The focus is on time-homogeneous diffusions with various boundaries and imposed killing. Employing spectral expansion theory, we derive explicit formulas for distributions of last passage times in common processes such as Drifted Brownian Motion (BM), Squared Bessel (SQB), Ornstein-Uhlenbeck (OU), and Cox-Ingersoll-Ross (CIR) models. …

Mapping With The Land: Co-Developing A Cumulative Impact Monitoring And Land Stewardship Framework With Sambaa K’E First Nation, Northwest Territories, Canada, Michael S. Mcphee

Theses and Dissertations (Comprehensive)

Across the Northwest Territories (NWT), Canada, Indigenous populations are striving to achieve effective environmental protection, whilst navigating complex methods, policies, and research relationships within co-management contexts. This thesis seeks to identify how differing cultural systems, environmental change, and fractured partnerships may be unified to align with the needs of the Sambaa K’e First Nation (SKFN), a remote Dehcho Dene community. Indigenous methodologies guided co-development of research questions with SKFN leadership which yielded objectives a) develop a GIS-based method to manage, organize and mobilize cultural and environmental data; b) develop a new stewardship monitoring procedure so that users can apply the …

Assessing Stormwater Management Pond Water Quality, Function, And The Potential Biotic Effects To Receiving Waters, Mitchell Elstone

Theses and Dissertations (Comprehensive)

The use of stormwater management ponds (SWMPs) has been increasing over the past five decades. However, an in-depth understanding of the daily performance of SWMPs and functionality during cold periods is limited. This is in part because mandated monitoring is relatively infrequent, and the assumption that SWMPs are inactive between storm events and during the winter. The goals of this research were to better understand daily stormwater (SW) characteristics, the performance of SWMPs based on current forms of evaluation and assess the potential for SWMP effluent to impact downstream biota. Influent and effluent samples from two SWMPs were collected daily …

Chirality Determination Using Three-Wave Mixing Microwave Spectroscopy, Nicole Taylor Moon

Doctoral Dissertations

"Rotational spectroscopy has established itself as a reliable gas-phase spectroscopic technique for the structural determination of molecules. This reliability has stemmed from both advancements in microwave technology and a willingness from the community to push the boundaries of the field. In this dissertation, the boundaries are tested in both how well the technique can determine the structure of molecules exhibiting large amplitude motion and through chirality determination. The first half of this dissertation explores the use of deep averaging to determine the structure of silicon containing molecules in collaboration with Dr. Guirgis from the College of Charleston. For each of …

The Science Of Gravitational-Wave Sources And Beyond Compact Binary Coalescences, Yanyan Zheng

Doctoral Dissertations

"This work focuses on the field of gravitational-wave astronomy by extending the scope of detectable sources beyond compact binary coalescences, All the gravitational-wave detections so far come from compact binary coalescences. Focusing on core-collapse supernovae as promising sources for short gravitational-wave transients, this work reports optically targeted searches for gravitational-wave emitted by core-collapse supernovae during the third observing run of the LIGO and Virgo detectors. It also predicts the search sensitivity for the ongoing fourth and forthcoming fifth observing runs. Moreover, the work introduces a novel computational framework for testing the spatial distribution of binary black hole sources, allowing for …

Secure And Privacy-Preserving Federated Learning With Rapid Convergence In Leo Satellite Networks, Mohamed Elmahallawy

Doctoral Dissertations

"The advancement of satellite technology has enabled the launch of small satellites equipped with high-resolution cameras into low Earth orbit (LEO), enabling the collection of extensive Earth data for training AI models. However, the conventional approach of downloading satellite-related data to a ground station (GS) for training a centralized machine learning (ML) model faces significant challenges. Firstly, the transmission of raw data raises security and privacy concerns, especially in military applications. Secondly, the download bandwidth is limited, which puts a stringent limit on image transmissions to the GS. Lastly, LEO satellites have sporadic visibility with the GS, and orbit the …

Crystal Structure Prediction Of Metal Chalcogenides, Qi Zhang

Doctoral Dissertations

A novel crystal structure prediction (CSP) method has been developed to predict energetically favorable (stable) structures based on targeted chemical compositions. It leverages the structural characteristics of recurring motifs featured in many crystals and symmetry restrictions from space groups to effectively lower the degrees of freedom of a system when conducting CSP simulations. The proposed method is applied to predicting low-energy structures of two metal chalcogenide systems: Li₃PS₄ and Na₆Ge₂Se₆. Both systems feature rigid bodies in their structures as building blocks, making them particularly suited to the proposed method. The validity …

Re-Evaluating Missouri’S Strategic Element Potential: A Geochemical Study Of The Mesoproterozoic Fe-Cu-Co-Ree Deposits In Southeast Missouri, Usa, Brandon James Sullivan

Doctoral Dissertations

"Iron-oxide-copper-gold (IOCG) deposits are poorly understood mineral systems. For example, we do not know why Cu- and Co-rich IOCG deposits typically occur proximal to Fe ore deposits that are notably Cu and Co-poor, such as Iron Oxide Apatite (IOA) deposits. To better understand the formation of IOA and IOCG deposits in Missouri, USA, this PhD thesis examines the genesis of the Kratz Spring IOA and the Boss Central Dome IOCG deposits. This study presents the first constraints on formation conditions and fluid sources in the studied deposits using integrated petrographic, mineral composition, and Fe isotope analyses of oxide minerals. Observations …

Design, Synthesis, And Characterization Of Complex Chalcogenides For Energy Storage And Energy Conversion Applications, Srikanth Balijapelly

Doctoral Dissertations

"Through this investigation, complex chalcogenides with the combination of main group metals, transition metals, and rare earth metals have been synthesized using the building block approach and their structure-property relationships are evaluated. The main emphasis of research is on rationally designing new materials for applications in sodium and lithium ion conducting solid electrolytes, cathodes, thermoelectrics, and nonlinear optics. Along with the experimental studies, theoretical calculations are also employed to better understand the physicochemical properties of the synthesized compounds.

The first part of the research will discuss designing alkali ion containing complex chalcogenides using the building block approach. This investigation resulted …

Dynamics And Inverse Problems For Nonlinear Schrödinger Equations, Christopher Hogan

Doctoral Dissertations

"The cubic nonlinear Schrödinger equation (NLS) is a model of interest in the study of physical problems including nonlinear optics and Bose-Einstein condensates. Of particular interest is the study of cubic NLS with inhomogeneities such as localizations of the nonlinearity or terms introducing potential barriers. We first address some preliminaries and techniques useful in the study of the cubic NLS and its variations. We then consider the cubic NLS with a localized nonlinearity in dimensions d ≥ 2. We show that solutions with data given by small-amplitude wave packets accrue a nonlinear phase that determines the X-ray transform of the …

Analytical Methods For Monitoring Traumatic Brain Injury Biomarkers/Treatment And Pharmaceutical Residual Solvents, Olajide Philip Adetunji

Doctoral Dissertations

"The development of highly sensitive and efficient analytical methods utilizing advanced instrumentation is necessary to help improve disease diagnosis and therapeutics. A major neuro-consequence of traumatic brain injury (TBI) is oxidative stress from the generation of reactive oxygen species and the depletion of antioxidant defenses. Alteration in concentrations of certain small molecules also occurs with the disease progression and can help understand TBI pathophysiology. Two analytical methods employing liquid chromatography with tandem mass spectrometry (LC-MS/MS) were developed and validated to monitor the potential small-molecule TBI biomarkers at sub-ppb levels. Subsequently, the neuroprotective effect of an antioxidant prodrug, N-acetylcysteine amide (NACA), …

Catalytic Control Of The Nanomorphology And Mechanical Properties Of Aliphatic Shape-Memory Aerogels, A B M Shaheen Ud Doulah

Doctoral Dissertations

"Shape-memory poly(isocyanurate-urethane) (PIR-PUR) aerogels are nanoporous solids that can return to their original shape after being compressed, through a heating actuation step. This thesis compares the effectiveness of various metal ions as catalysts in the formation of PIR-PUR aerogels, and explores the correlation between catalytic activity, nanomorphology, and mechanical properties of the resulting aerogels. The gelation rate was found to increase from Fe to Cu and then decline from Cu to Ga in the periodic table. CuCl₂ was found to be the fastest catalyst, and FeCl₃ the slowest. The morphology of the aerogels changed from bicontinuous to spheroidal …

High-Resolution Spectroscopy Of Interstellar Lines And Comets, Chemeda Tadese Ejeta

Doctoral Dissertations

"The study of interstellar molecules such as CO is crucial because interstellar ices in the core of a pre-solar molecular cloud provide the starting point for volatile evolution in the protoplanetary disk. A record of the initial volatile composition of the protoplanetary disk can be obtained from the study of the chemical composition of cometary nuclei. Because of their long residence in the Oort cloud and infrequent passage through the inner solar system, long-period comets are one of the most primitive bodies in our solar system that can tell us about the composition of the early solar system. High-resolution infrared …

Critical Behavior And Dynamics Of The Superfluid-Mott Glass Transition, Jack Russell Crewse

Doctoral Dissertations

This work studies the effects of disorder on the thermodynamic critical behavior and dynamical properties of the superfluid-Mott glass quantum phase transition. After a brief introduction covering relevant fundamentals, we present the dissertation in the form of four separate but related publications. In the first two publications, we calculate the thermodynamic critical exponents of the superfluid-Mott glass quantum phase transition in both two and three spatial dimensions. The undiluted transition exhibits critical exponents that violate the Harris criterion, and thus the critical behavior is expected to change upon introducing disorder. We confirm this behavior via Monte Carlo simulation of a …

External Support Structures In Fused Deposition Modeling 3d Printing, Adam Mystkowski

Undergraduate Honors Theses

3D Printing, sometimes also referred to as Additive Manufacturing, is a technology that has garnered a lot of attention in the past several years. While the technology has attracted a significant community of hobbyists, the benefits of the technology have also been recognized in manufacturing. While there are many different types of 3D Printing techniques, the most common type is Fused Deposition Modeling (FDM), mainly due to its relatively low cost compared to other types. However, the technique also present a significant limitation: it tends to struggle with models that have overhanging parts. When a layer is extruded by an …

Community Science Informs Movement And Reproductive Ecology Of Sand Tigers Carcharias Taurus Off North Carolina, United States Of America, Carol Seals Price, Ara Lupton Mcclanahan, Erin J. Burge, Tanya Houppermans, Jason Holmberg

Marine Science

Sand tigers are frequently observed at shipwrecks and other artificial reef habitats off North Carolina (USA), but data about occupancy, movement ecology, and site fidelity are lacking. Spot A Shark USA researchers used Wildbook^© photoidentification software to spot map sand tigers in images provided by recreational SCUBA divers, or collected from remotely operated vehicles, and an offshore live-streaming camera. We uniquely identified 1837 sand tigers, 101 of which were resighted on more than one date between 2005–2021. Sand tigers of both sexes and various ages were found year-round along the northern, central and southern coast. We identified shipwrecks or …

A “War” Over Lobster And Whales: The Issue-Attention Cycle, Media Discourse, And Political Ecology Of Right Whale Science And Conservation In Six Us Newspapers, Marcus Reamer, Catherine Macdonald, Julia Wester, Russell Fielding, Meryl Shriver-Rice

Honors College Faculty Publications

News organizations and journalists are important and influential actors in environmental politics. Their reporting on social and environmental issues often follows issue-attention cycles (IACs) that emphasize drama and problematization to maintain public interest. This study examined nearly 13 years of news coverage to understand the media discourse about the Critically Endangered North Atlantic right whale (NARW) and its conservation. Content analysis and critical discourse analysis were used to analyze 356 texts published in six large US newspapers between January 1, 2010 and March 15, 2023. NARW conservation and management received increased public attention and an IAC began in 2017 after …

Decoding U.S. Tort Liability In Healthcare's Black-Box Ai Era: Lessons From The European Union, Mindy Duffourc, Sara Gerke

Faculty Scholarly Works

The rapid development of sophisticated artificial intelligence (“AI”) tools in healthcare presents new possibilities for improving medical treatment and general health. Currently, such AI tools can perform a wide range of health-related tasks, from specialized autonomous systems that diagnose diabetic retinopathy to general-use generative models like ChatGPT that answer users’ health-related questions. On the other hand, significant liability concerns arise as medical professionals and consumers increasingly turn to AI for health information. This is particularly true for black-box AI because while potentially enhancing the AI’s capability and accuracy, these systems also operate without transparency, making it difficult or even impossible …

Data Science In Finance: Challenges And Opportunities, Xianrong Zheng, Elizabeth Gildea, Sheng Chai, Tongxiao Zhang, Shuxi Wang

Information Technology & Decision Sciences Faculty Publications

Data science has become increasingly popular due to emerging technologies, including generative AI, big data, deep learning, etc. It can provide insights from data that are hard to determine from a human perspective. Data science in finance helps to provide more personal and safer experiences for customers and develop cutting-edge solutions for a company. This paper surveys the challenges and opportunities in applying data science to finance. It provides a state-of-the-art review of financial technologies, algorithmic trading, and fraud detection. Also, the paper identifies two research topics. One is how to use generative AI in algorithmic trading. The other is …

Radiation Pressure Induced Oscillations Of An Optically Levitating Mirror, Satyam Shekhar Jha, Tal Carmon, Fan Cheng, Lev Deych

Publications and Research

Optical Fabry–Perot cavity with a movable mirror is a paradigmatic optomechanical system. While usually the mirror is supported by a mechanical spring, it has been shown that it is possible to keep one of the mirrors in a stable equilibrium purely by optical levitation without any mechanical support. In this work, we expand previous studies of the nonlinear dynamics of such a system by demonstrating a possibility for mechanical parametric instability and the emergence of the “phonon laser” phenomenon.