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Full-Text Articles in Physical Sciences and Mathematics

Shadows Of A Schwarzschild Black Hole Surrounded By A Spherically Symmetric Dark Matter, Ahmad Ibrahim Jun 2022

Shadows Of A Schwarzschild Black Hole Surrounded By A Spherically Symmetric Dark Matter, Ahmad Ibrahim

Theses and Dissertations

In this thesis, using general relativity, the null geodesics and black hole shadow of a spherically symmetric configuration of a black hole (surrounded by a dark matter shell) are studied. First, the standard

results of the photon sphere of Schwarzschild de-Sitter black hole is revisited and analyzed more carefully. Secondly, using an ansatz (piecewise metric function) commonly used in the literature to describe the mass distribution of the spherically symmetric black hole - dark matter configuration, the null geodesics through vacuum and dark matter are analyzed. Assuming an observer located at a finite distance from the black hole outside the dark ...


Enhancing Vanadium Redox Battery Performance Using Tungsten-Bismuth-Based Oxide Nanostructures As Electrode Modifiers, Taher Al Najjar Jun 2022

Enhancing Vanadium Redox Battery Performance Using Tungsten-Bismuth-Based Oxide Nanostructures As Electrode Modifiers, Taher Al Najjar

Theses and Dissertations

Renewable energy power plants require high efficiency conversion and storage systems that can store high amounts of energy and can be integrated with the electrical grid. Vanadium redox flow batteries are very promising for this application. However, one major drawback of VRFBs is their low power density which means that right now they cannot replace non-renewable energy sources. Different carbon materials are used as electrodes in VRFBs and each carbon material affects the battery’s performance in a different way. Modification of these electrodes can increase the power density of the battery. Some metal oxides like tungsten oxide can enhance ...


The Mathematical Foundation Of The Musical Scales And Overtones, Michaela Dubose-Schmitt May 2022

The Mathematical Foundation Of The Musical Scales And Overtones, Michaela Dubose-Schmitt

Theses and Dissertations

This thesis addresses the question of mathematical involvement in music, a topic long discussed going all the way back to Plato. It details the mathematical construction of the three main tuning systems (Pythagorean, just intonation, and equal temperament), the methods by which they were built and the mathematics that drives them through the lens of a historical perspective. It also briefly touches on the philosophical aspects of the tuning systems and whether their differences affect listeners. It further details the invention of the Fourier Series and their relation to the sound wave to explain the concept of overtones within the ...


Incorporating Spatial Relationship Information In Signal-To-Text Processing, Jeremy Elon Davis May 2022

Incorporating Spatial Relationship Information In Signal-To-Text Processing, Jeremy Elon Davis

Theses and Dissertations

This dissertation outlines the development of a signal-to-text system that incorporates spatial relationship information to generate scene descriptions. Existing signal-to-text systems generate accurate descriptions in regards to information contained in an image. However, to date, no signalto- text system incorporates spatial relationship information. A survey of related work in the fields of object detection, signal-to-text, and spatial relationships in images is presented first. Three methodologies followed by evaluations were conducted in order to create the signal-to-text system: 1) generation of object localization results from a set of input images, 2) derivation of Level One Summaries from an input image, and ...


Against The Clock: Uncovering Diurnal Time Interval Decision Differences During Tornado Warnings For Lower Mississippi Valley Residents, Stephen Holden Wooten May 2022

Against The Clock: Uncovering Diurnal Time Interval Decision Differences During Tornado Warnings For Lower Mississippi Valley Residents, Stephen Holden Wooten

Theses and Dissertations

With a higher number of nocturnal tornado events, I surveyed residents of Alabama, Arkansas, Kentucky, Mississippi, and Tennessee (N = 487 for each sample) to determine the time, in minutes, it took to reach a decision on shelter-seeking. I utilized latent class analysis (LCA) to create class memberships, based on diurnal and nocturnal scenarios, to associate with time intervals. Four actors were identified for each scenario: Tech Users, Typical Actors, Non-Reactors, and Social Actors for the day sample, Tech Users, Typical Actors, Passive Actors, and Non-Reactors for the night sample. Time intervals were created and applied to each class. All class ...


Direct Simulation And Reduced-Order Modeling Of Premixed Flame Response To Acoustic Modulation, Zheng Qiao May 2022

Direct Simulation And Reduced-Order Modeling Of Premixed Flame Response To Acoustic Modulation, Zheng Qiao

Theses and Dissertations

This dissertation introduces a general, predictive and cost-efficient reduced-order modeling (ROM) technique for characterization of flame response under acoustic modulation. The model is built upon the kinematic flame model–G-equation to describe the flame topology and dynamics, and the novelties of the ROM lie in i) a procedure to create the compatible base flow that can reproduce the correct flame geometry and ii) the use of a physically-consistent acoustic modulation field for the characterization of flame response. This ROM addresses the significant limitations of the classical kinematic model, which is only applicable to simple flame configurations and relies on ad-hoc ...


Exploring The Impact Of End-User Engagement On The Diffusion And Adoption Of A Climate Resilience Tool In The Gulf Of Mexico, Renee C. Collini May 2022

Exploring The Impact Of End-User Engagement On The Diffusion And Adoption Of A Climate Resilience Tool In The Gulf Of Mexico, Renee C. Collini

Theses and Dissertations

Climate change-related hazards negatively impact ecosystems, economies, and quality of life. Significant resources have been invested in data collection and research with the goal of enhanced understanding and capacity to predict future conditions in order to mitigate or adapt to intensifying hazard risk. The expansive production of climate science has generated a necessary complimentary enterprise dedicated to enhancing decision-makers’ understanding of and access to climate science as it is essential for future societal and ecological well-being. Though the aim of these many tools is to support resilient decision-making in the face of climate change, professionals report an underutilization of climate ...


Functionalized Biochar Electrodes For Asymmetric Capacitive Deionization, Hellen Stephanie May 2022

Functionalized Biochar Electrodes For Asymmetric Capacitive Deionization, Hellen Stephanie

Theses and Dissertations

Electrosorption-based capacitive deionization (CDI) has become a viable process for brackish water desalination and defluoridation. In this study, activated Douglas fir biochar is used as a low-cost electrode material with adsorption capacity comparable to activated carbon obtained from biomass precursors. Adding functional groups to the activated biochar enhanced salt removal capacity, providing cation and anion selectivity. The functionalized electrodes were prepared by Nafion, titanium isopropoxide, and p-phenylenediamine treatment, respectively, which introduced sulfonate, titanium dioxide and amine functional groups to the electrode surface. These modification methods are versatile and can be easily performed without sophisticated laboratory environment. Modified biochar electrodes ...


Photocatalytic Degradation Of Organic Contaminants By Titania Particles Produced By Flame Spray Pyrolysis, Noah Babik May 2022

Photocatalytic Degradation Of Organic Contaminants By Titania Particles Produced By Flame Spray Pyrolysis, Noah Babik

Theses and Dissertations

Advanced oxidation of organic pollutants with TiO2 photocatalysts is limited due to the wide bandgap of TiO2, 3.2 eV, which requires ultraviolet (UV) radiation. When nanosized TiO2 is modified by carbon doping, charge recombination is inhibited and the bandgap is narrowed, allowing for efficient photodegradation under visible light. Here, we propose a flame spray pyrolysis (FSP) technique to create TiO2. The facile process of FSP has been successful in preparing highly crystalline TiO2 nanoparticles. Using the same procedure to deposit TiO2 onto biochar, the photocatalyst was doped by the carbonaceous material. The morphology, crystalline and electronic structure of the ...


Evaluating The Persuasiveness Of Mobile Health: The Intersection Of Persuasive System Design And Data Science, Aleise Mcgowan May 2022

Evaluating The Persuasiveness Of Mobile Health: The Intersection Of Persuasive System Design And Data Science, Aleise Mcgowan

Theses and Dissertations

Persuasive technology is an umbrella term that encompasses any software (e.g., mobile app) or hardware (e.g., smartwatch) designed to influence users to perform a preferable behavior once or on a long-term basis. Considering the ubiquitous nature of mobile devices across all socioeconomic groups, user behavior modification thrives under the personalized care that persuasive technology can offer. This research examines the roles psychological characteristics play in interpreted mHealth screen perceived persuasiveness. A review of the literature revealed a gap regarding how developers of digital health technologies are often tasked with developing tools designed to engage patients, yet little emphasis ...


Adversarial Machine Learning For The Protection Of Legitimate Software, Colby Parker May 2022

Adversarial Machine Learning For The Protection Of Legitimate Software, Colby Parker

Theses and Dissertations

Obfuscation is the transforming a given program into one that is syntactically different but semantically equivalent. This new obfuscated program now has its code and/or data changed so that they are hidden and difficult for attackers to understand. Obfuscation is an important security tool and used to defend against reverse engineering. When applied to a program, different transformations can be observed to exhibit differing degrees of complexity and changes to the program. Recent work has shown, by studying these side effects, one can associate patterns with different transformations. By taking this into account and attempting to profile these unique ...


Effective Cybersecurity Risk Management In Projects, Steven Scott Presley May 2022

Effective Cybersecurity Risk Management In Projects, Steven Scott Presley

Theses and Dissertations

Project meta-phases describe the life stages in which project and sponsoring organizations are exposed to cybersecurity risk. Three hypotheses were formulated to examine whether cybersecurity risk was evident in each of three project meta-phases. Project assets for a typical information systems project were identified and associated with each project meta-phase. Whitman’s Threat, Vulnerability and Asset (TVA) risk management process was used to create project threat scenarios, which formed the basis of a risk assessment questionnaire. An online tool was used to administer the survey to 66 project and/or cybersecurity professionals. Participants were asked to rate each scenario’s ...


Circuit-Variant Moving Target Defense For Side-Channel Attacks On Reconfigurable Hardware, Tristen H. Mullins May 2022

Circuit-Variant Moving Target Defense For Side-Channel Attacks On Reconfigurable Hardware, Tristen H. Mullins

Theses and Dissertations

With the emergence of side-channel analysis (SCA) attacks, bits of a secret key may be derived by correlating key values with physical properties of cryptographic process execution. Power and Electromagnetic (EM) analysis attacks are based on the principle that current flow within a cryptographic device is key-dependent and therefore, the resulting power consumption and EM emanations during encryption and/or decryption can be correlated to secret key values. These side-channel attacks require several measurements of the target process in order to amplify the signal of interest, filter out noise, and derive the secret key through statistical analysis methods. Differential power ...


Coastal Sediment Response To The Diel Oxygen Cycle, Kara Gadeken May 2022

Coastal Sediment Response To The Diel Oxygen Cycle, Kara Gadeken

Theses and Dissertations

Shallow coastal sediments are sites of intense respiration and organic matter breakdown. Macroinfauna bioturbate and bioirrigate sediments which supplies microbes with oxygen and newly deposited organic material from surface sediments, facilitating microbial remineralization of organic matter. These processes depend heavily on the concentration of dissolved oxygen in overlying water. Shallow water oxygen patterns often follow a diel cycle as dissolved oxygen decreases at night due to respiration and then increases during the day with photosynthesis, creating recurring suboxic conditions that are potentially stressful to organisms. Sediment oxygen flux is known to depend on ambient dissolved oxygen concentration, but behavioral responses ...


Slope Conjecture And Normal Surface Theory, Helene Swanepoel May 2022

Slope Conjecture And Normal Surface Theory, Helene Swanepoel

Theses and Dissertations

In this thesis we explore the relationship between quantum link invariants and the geometric and topological properties for a family of pretzel knots P(−2r, 2r + 1, 2r + s), r ≥ 1 and s ≥ 3, as predicted by the Slope conjecture. This conjecture asserts a connection between the degree of the colored Jones polynomial and boundary slopes of these knots. We introduce fundamentals of knot theory and prove that the minimum degree of the Jones polynomial for the family of pretzel knots P(−2r, 2r + 1, 2r + s), r ≥ 1 and s ≥ 3, is −6r − 3r + 3. In addition, we consider ...


Enhancing System Security Using Dynamic Hardware, Sydney L. Davis May 2022

Enhancing System Security Using Dynamic Hardware, Sydney L. Davis

Theses and Dissertations

Within the ever-advancing field of computing, there is significant research into the many facets of cyber security. However, there is very little research to support the concept of using a Field Programmable Gate Array (FPGA) to increase the security of a system. While its most common use is to provide efficiency and speedup of processes, this research considers the use of an FPGA to mitigate vulnerabilities in both software and hardware. This paper proposes circuit variance within an FPGA as a method of Moving Target Defense (MTD) and investigates its effect on side-channels. We hypothesize that although the functionality of ...


Identifying Text File Similarities In Forensic Disk Images Using Fuzzy Logic, Mindy M. Wongsa May 2022

Identifying Text File Similarities In Forensic Disk Images Using Fuzzy Logic, Mindy M. Wongsa

Theses and Dissertations

Digital storage is evolving with the growth of technology. Individuals and corporations can access large amounts of digital storage, leaving digital forensics investigators with large amounts of data to collect and analyze in their forensic investigation cases. In addition, analyzing forensic disk images that contain hundreds of thousands of files can cause a problem with time since the investigators’ workloads can vary based on how many cases they are assigned. Fuzzy logic provides a pattern recognition system that could assist in identifying patterns in data. The purpose of this study was to determine if fuzzy logic could reliably aid in ...


Synthesis, Characterization And Activity Of Palladium Catalysts On The Dual Support Of Cerium And Aluminum Oxides, Jihyeon Park Apr 2022

Synthesis, Characterization And Activity Of Palladium Catalysts On The Dual Support Of Cerium And Aluminum Oxides, Jihyeon Park

Theses and Dissertations

The effects of sequence of impregnation (Pd on cerium oxides -alumina and cerium oxides on Pd-alumina) and calcination temperature (500 ℃ and 850 ℃) on the catalytic oxidation of methane under lean conditions were investigated. The catalysts were prepared by a combination of impregnation, slurry and vortexing methods. The catalysts had 4.7 wt.% Pd and 10.7 wt.% Ce based on inductively coupled plasma optical emission spectrometry (ICP-OES) analysis. The catalysts were characterized by pulse chemisorption, temperature programmed reduction (TPD), scanning transmission electron microscopy (STEM), and X-ray photoelectron spectroscopy (XPS). The activity of the catalysts for methane combustion was measured in ...


Characterizing Equivalence And Correctness Properties Of Dynamic Mode Decomposition And Subspace Identification Algorithms, Samuel Gregory Neff Apr 2022

Characterizing Equivalence And Correctness Properties Of Dynamic Mode Decomposition And Subspace Identification Algorithms, Samuel Gregory Neff

Theses and Dissertations

We examine the related nature of two identification algorithms, subspace identification (SID) and Dynamic Mode Decomposition (DMD), and their correctness properties over a broad range of problems. This investigation begins by noting the strong relationship between the two algorithms, both drawing significantly on the pseudoinverse calculation using singular value decomposition, and ultimately revealing that DMD can be viewed as a substep of SID. We then perform extensive computational studies, characterizing the performance of SID on problems of various model orders and noise levels. Specifically, we generate 10,000 random systems for each model order and noise level, calculating the average ...


How Failures Cascade In Software Systems, Barbara W. Chamberlin Apr 2022

How Failures Cascade In Software Systems, Barbara W. Chamberlin

Theses and Dissertations

Cascading failures involve a failure in one system component that triggers failures in successive system components, potentially leading to system wide failures. While frequently used fault tolerant techniques can reduce the severity and the frequency of such failures, they continue to occur in practice. To better understand how failures cascade, we have conducted a qualitative analysis of 55 cascading failures, described in 26 publicly available incident reports. Through this analysis we have identified 16 types of cascading mechanisms (organized into eight categories) that capture the nature of the system interactions that contribute to cascading failures. We also discuss three themes ...


A Permutation-Based Confidence Distribution For Rare-Event Meta-Analysis, Travis Andersen Apr 2022

A Permutation-Based Confidence Distribution For Rare-Event Meta-Analysis, Travis Andersen

Theses and Dissertations

Confidence distributions (CDs), which provide evidence across all levels of significance, are receiving increasing attention, especially in meta-analysis. Meta-analyses allow independent study results to be combined to produce one overall conclusion and are particularly useful in public health and medicine. For studies with binary outcomes that are rare, many traditional meta-analysis methods often fail (Sutton et al. 2002; Efthimiou 2018; Liu et al. 2018; Liu 2019; Hunter and Schmidt 2000; Kontopantelis et al. 2013). Zabriskie et al. (2021b) develop a permutation-based method to analyze such data when study treatment effects vary beyond what is expected by chance. In this work ...


The Perception Of At-Risk Students On Caring Student-Teacher Relationships And Its Impact On Their Productive Disposition, Brittany Hopper Apr 2022

The Perception Of At-Risk Students On Caring Student-Teacher Relationships And Its Impact On Their Productive Disposition, Brittany Hopper

Theses and Dissertations

The importance of a positive, caring relationship with students in the classroom is under-researched in mathematics education. Research shows that a positive student-teacher relationship can have many long-term positive results for the student. Many of these results directly impact a student's productive disposition towards mathematics. At-risk students are in greater need of positive relationships and an increase in productive disposition. Using Joan Tronto's (1993) elements of care, I examine the student perspective of these kinds of relationships and how the student sees development of their own productive disposition.


A Multidimensional Convolutional Bootstrapping Method For The Analysis Of Degradation Data, Jared M. Clark Apr 2022

A Multidimensional Convolutional Bootstrapping Method For The Analysis Of Degradation Data, Jared M. Clark

Theses and Dissertations

While Monte Carlo methods for bootstrapping are typically easy to implement, they can be quite time intensive. This work aims to extend an established convolutional method of bootstrapping to work when convolutions in two or more dimensions are required. The convolutional method relies on efficient computational tools rather than Monte Carlo simulation which can greatly reduce the computation time. The proposed method is particularly well suited for the analysis of degradation data when the data are not collected on time intervals of equal length. The convolutional bootstrapping method is typically much faster than the Monte Carlo bootstrap and can be ...


Accurate Band Energies Of Metals With Quadratic Integration, Jeremy John Jorgensen Apr 2022

Accurate Band Energies Of Metals With Quadratic Integration, Jeremy John Jorgensen

Theses and Dissertations

Materials play an important role in society. Historically, and even at present, materials have been discovered by trial and error, and many of the most useful materials have been discovered by chance. The high-throughput approach aims to remove (as much as possible) chance and guesswork at the experimental level by filtering out materials candidates that are not predicted to exist. Many successes have been recorded. In the high-throughput approach to materials discovery, machined-learned models of materials are created from databases of theoretical materials. These databases are the result of millions of density-functional-theory (DFT) simulations. The size and accuracy of the ...


Inhibition Of Cell Adhesion And Actin Localization During Migration Upon Protective Antigen Mutant Ligand Binding To The Capillary Morphogenesis Gene 2, Sai Lun Lee Apr 2022

Inhibition Of Cell Adhesion And Actin Localization During Migration Upon Protective Antigen Mutant Ligand Binding To The Capillary Morphogenesis Gene 2, Sai Lun Lee

Theses and Dissertations

Capillary Morphogenesis Gene 2 protein (CMG2) is a type 1 transmembrane receptor known as the anthrax toxin receptor 2 (ANTXR2). While it is documented that the cell surface receptor CMG2 mediates anthrax toxin entry into the cell via endocytosis, the physiological role of CMG2 is not well understood. Others have suggested that CMG2 may have a role in mediating ECM homeostasis and angiogenesis. Additionally, both anthrax protective antigen (PA) and a furin protease-resistant mutant, PASSSR, inhibit corneal neovascularization in a mouse model, and interestingly PASSSR has a greater affinity to CMG2 receptor. PASSSRalso has a more potent antiangiogenic effect than ...


Physics-Guided Machine Learning In Ocean Acoustics Using Fisher Information, Michael Craig Mortenson Apr 2022

Physics-Guided Machine Learning In Ocean Acoustics Using Fisher Information, Michael Craig Mortenson

Theses and Dissertations

Waterborne acoustic signals carry information about the ocean environment. Ocean geoacoustic inversion is the task of estimating environmental parameters from received acoustic signals by matching the measured sound with the predictions of a physics-based model. A lower bound on the uncertainty associated with environmental parameter estimates, the Cramér-Rao bound, can be calculated from the Fisher information, which is dependent on derivatives of a physics-based model. Physics-based preconditioners circumvent the need for variable step sizes when computing numerical derivatives. This work explores the feasibility of using a neural network to perform geoacoustic inversion for environmental parameters and their associated uncertainties from ...


“If I Could Do This, I Feel Anyone Could:” The Design And Evaluation Of A Two-Factor Authentication Manager, Garrett D. Smith Apr 2022

“If I Could Do This, I Feel Anyone Could:” The Design And Evaluation Of A Two-Factor Authentication Manager, Garrett D. Smith

Theses and Dissertations

Two-factor authentication (2FA) is a strong defense against account compromise. However, usability studies reveal challenges with 2FA setup. The process to manually setup and remove 2FA methods differs across websites. We present a system design for a 2FA manager to automatically setup and remove 2FA methods. Potential benefits are reduced time, fewer mistakes, consistent terminology, a single workflow for users to learn, and the ability to rapidly transition to a new 2FA method—e.g., when replacing a lost 2FA method. We create two proof-of-concept implementations of our design, one as a browser extension and one integrated as a feature ...


Using Connections To Make Predictions On Dynamic Networks, Rebecca Dorff Jones Apr 2022

Using Connections To Make Predictions On Dynamic Networks, Rebecca Dorff Jones

Theses and Dissertations

Networks are sets of objects that are connected in some way and appear abundantly in nature, sociology, and technology. For many centuries, network theory focused on static networks, which are networks that do not change. However, since all networks transform over time, static networks have limited applications. By comparison, dynamic networks model how connections between objects change over time. In this work, we will explore how connections in dynamic networks change and how we can leverage these changes to make predictions about future iterations of networks. We will do this by first considering the link prediction problem, using either Katz ...


Statistical Properties Of 2d Navier-Stokes Equations Driven By Quasi-Periodic Force And Degenerate Noise, Rongchang Liu Apr 2022

Statistical Properties Of 2d Navier-Stokes Equations Driven By Quasi-Periodic Force And Degenerate Noise, Rongchang Liu

Theses and Dissertations

We consider the incompressible 2D Navier-Stokes equations on the torus driven by a deterministic time quasi-periodic force and a noise that is white in time and extremely degenerate in Fourier space. We show that the asymptotic statistical behavior is characterized by a uniquely ergodic and exponentially mixing quasi-periodic invariant measure. The result is true for any value of the viscosity ν > 0. By utilizing this quasi-periodic invariant measure, we show the strong law of large numbers and central limit theorem for the continuous time inhomogeneous solution processes. Estimates of the corresponding rate of convergence are also obtained, which is the ...


Stabilizing Controlled Systems In The Presence Of Time-Delays, Isaac Becker Pardo Apr 2022

Stabilizing Controlled Systems In The Presence Of Time-Delays, Isaac Becker Pardo

Theses and Dissertations

A dynamical system's state evolves over time, and when the system stays near a particular state this state is known as a stable state of the system. Through control methods, dynamical systems can be manipulated such that virtually any state can be made stable. Although most real systems evolve continuously in time the application of digital control methods to these systems is inherently discrete. States are sampled (with sensors) and fed back into the system in discrete-time to determine the input needed to control the continuous system. Additionally, dynamical systems often experience time delays. Some examples of time delays ...