Physical Sciences and Mathematics Commons^™

Temporal Dynamics Of Coastal Sediment Characteristics: A Comparative Study On Pre- And Post-2004 Tsunami Event Along The Nagoor - Poompuhar Stretch, Tamil Nadu, Yamini S

Theses and Dissertations

Tsunamis represent some of the most devastating natural events for coastal regions, as exemplified by the 26th December 2004 Great Indonesian Earthquake triggered a massive tsunami across the Bay of Bengal and Indian Ocean, causing extensive destruction in various countries, including India. This study addresses a significant gap in the literature by focusing on the detailed sedimentological aspects of coastal dynamics. Specifically, it examines the pre-tsunami (December 2004), post-tsunami (January 2005), and recent (December 2022) sediment characteristics along a 35 km stretch of the Coromandel coast from Poompuhar to Nagoor.

Eight stations were selected for sampling: Poompuhar, Chinnankudi, Kuttyandiyur, Chandrapadi, …

Investigations On V2o5 And Its Derivative Nanocomposites For Photocatalytic Textile Organic Dye Degradation, Jenifer A

Theses and Dissertations

In recent times, organic dyes from industrial sludge become one of the significant causes of water contamination due to their utility in textile and paper manufacturing industries. These organic dyes are highly toxic and carcinogenic. Fortunately, the photocatalytic degradation process is a practical tool for decomposing toxic organic matter in wastewater by utilizing light. The photodegradation process can be performed using semiconductor materials to purify wastewater. Thus, semiconductor photocatalysis is a desirable alternative technique for decolorizing various organic pollutants.

In this context, the present work reports the preparation and characterization of V2O5 nanocomposites by facile methods and tests them against …

Mg3sb2-Based Materials For Mid-Temperature Thermoelectric Application, Veera Prabhu K

Theses and Dissertations

Recently, there has been growing research in the scientific community regarding the conversion of heat flux into electricity, which has proven effective in mitigating energy crises. Solid-state thermoelectric (TE) devices use the Seebeck effect to efficiently convert waste heat into electricity. Traditional materials contain toxic, rare, and expensive elements like Lead, Tellurium, and Germanium that restrict large-scale production, commercialization, and practical utilization.

Recently, Mg3Sb2-based materials have been attractive due to their remarkable characteristics, including abundance, affordability, and environmental friendliness. Furthermore,n-type Mg3Sb2-based materials exhibit high TE performance because of their high band degeneracy in the conduction band minimum (CBM), and low …

Emergence Of Extreme Events In Nonlinear Oscillators Due To Parametric And External Excitations, Kaviya B

Theses and Dissertations

This comprehensive PhD thesis immerses itself in the intricate world of dynamical systems, aiming to understand, characterize, and develop innovative mitigation strategies for rare and extreme events occurring within diverse nonlinear oscillatory models. The term "events" spans a broad array of occurrences within defined systems, with "rare events" standing out as infrequent outliers or deviations from the norm.

Rare events span various disciplines such as oceanography, climate studies, biology, economics, ecology, encompassing phenomena like rogue waves, floods, cyclones, earthquakes, and financial crises. Recognized for their potential to cause substantial harm to both society and the environment, these events are widely …

Geology Of Sinai Tholus, Thaumasia Plateau, Mars, Haley Mosher

Theses and Dissertations

A new geologic map of the Sinai Tholus region on the Thaumasia plateau, Mars reveals the structural, magmatic, and stratigraphic complexity that can be found in the Tharsis region on Mars, and may help answer key questions about the origin of the subvolcanic basement, evolution of the regional stress field, development of Valles Marineris, and magmatic history of the region. Sinai Tholus is a topographic high in a relatively flat, lava flow covered part of Thaumasia Plateau, just south of the central part of Valles Marineris. Here, five stratigraphic units and one generalized impact unit have been mapped at a …

Hot Wire Chemical Vapor Deposition Of Tungsten Oxides For Photocatalytic Hydrogen Production From Water, Marvin Bonney

Theses and Dissertations

Anthropogenic climate change has generated an ever-increasing global ecological, economic, and political disaster for the world. In order to contain the damage and bring atmospheric carbon under control, human use of non-renewable hydrocarbons as the primary source of fuels for transportation and electrical generation needs to be phased out at the earliest possible date. Renewable, clean energy generation is currently technologically feasible and could provide the means for decarbonization of the global energy economy, but has to overcome challenges related to the intermittency of production. Hydrogen gas is a clean burning, renewable, and highly flexible method of storing such energy …

Evaluating Audio-Compression Techniques, Thien Tuong Duong

Theses and Dissertations

Perceptual quality of audio is the aural accuracy and fidelity perceived by the listener. It is how humans respond to the accuracy, intelligibility, or fidelity of aural media. High-fidelity audio represents high accuracy and minimal distortion and is the standard against which compression algorithms are assessed. We argue that maintaining high-fidelity audio is not just a technical requirement but is also about respecting the artistry of music production. The primary goal of this thesis is to compare the performance of popular audio codecs including file size and conversion speed of each codec when encoding the same file. A secondary goal …

Mild Hydrothermal Crystal Growth Strategies For Complex Inorganic Metal Fluorides, Navindra Keerthisinghe

Theses and Dissertations

Inorganic metal fluorides have been investigated for their interesting magnetic and optical properties, their electrochemical behavior, and their ionic conductivity. Fluoride materials can accommodate metals in very low oxidation states, which can be advantageous for designing new magnetic materials. Specifically, mixed metal fluorides incorporating transition metal cations often exhibit interesting magnetic behavior, such as frustrated magnetism. However, many challenges are encountered during the synthesis of such fluoride materials, including the inability to perform reactions under ambient conditions and the involvement of toxic gases for fluorination during solid-state reactions. Therefore, solution growth techniques such as mild hydrothermal synthesis are currently utilized …

Predictive Filtering-Based Image Inpainting, Xiaoguang Li

Theses and Dissertations

Image inpainting is an important challenge in the computer vision field. The primary goal of image inpainting is to fill in the missing parts of an image. This technique has many real-life uses including fixing old photographs and restoring ancient artworks, e.g., the degraded Dunhuang frescoes. Moreover, image inpainting is also helpful in image editing. It has the capability to eliminate unwanted objects from images while maintaining a natural and realistic appearance, e.g., removing watermarks and subtitles. Disregarding the fact that image inpainting expects the restored result to be identical to the original clean one, existing deep generative inpainting methods …

Synergetic And Orthogonal Switching In Dual Photochromic Metal-Organic Frameworks, Gina Rene Wilson

Theses and Dissertations

Cooperative behavior and orthogonal responses of two classes of coordinatively integrated photochromic molecules towards distinct external stimuli were demonstrated on the first example of a photo-thermo-responsive hierarchical platform. Synergetic and orthogonal responses to temperature and excitation wavelength are achieved by confining the stimuli-responsive moieties within a metal-organic framework (MOF), leading to the preparation of a novel photo-thermo-responsive spiropyran-diarylethene based material. Synergistic behavior of two photoswitches enables the study of stimuli-responsive resonance energy transfer as well as control of the photoinduced charge transfer processes, milestones required to advance optoelectronics development. Spectroscopic studies in combination with theoretical modeling revealed a nonlinear effect …

Electron Rich Cobaltocenium Derivatives As Tunable Mechanophores For Mechanochemistry, Luis Daniel Ramos

Theses and Dissertations

In this dissertation, metallocene-containing polymers are investigated and probed for tunability in mechanochemistry. These metallocene moieties are experimentally and computationally characterized.

In chapter 1, relevant background and recent developments of metallocene-containing polymers are discussed. Additionally, the field of mechanochemistry is briefly introduced including applications and future directions within the field.

In chapter 2, design and synthesis of these metallocene-containing polyelectrolytes via ring opening metathesis polymerization (ROMP) are outlined. These polymers then undergo mechanophore activation via ultrasonication and relevant analysis and characterization of polymers both before and after ultrasonication are detailed. These polymers are comprised of differing electron donating substituents on …

Modeling, Analysis, Approximation, And Application Of Viscoelastic Structures And Anomalous Transport, Yiqun Li

Theses and Dissertations

(Variable-order) fractional partial differential equations are emerging as a competitive means to integer-order PDEs in characterizing the memory and hereditary properties of physical processes, e.g., anomalously diffusive transport, viscoelastic mechanics and financial mathematics, and thus have attracted widespread attention. In particular, optimal control problems governed by fractional partial differential equations are attracting increasing attentions since they are shown to provide competitive descriptions of challenging physical phenomena. Nevertheless, variable-order fractional models exhibit salient features compared with their constant-order analogues and introduce mathematical difficulties that are not typical encountered in the context of integer-order and constant-order fractional partial differential equations.

This dissertation …

Controlling Properties Of Hybrid Materials: Leaching Kinetics And Electronic Structure, Anna Berseneva

Theses and Dissertations

Hybrid materials are a unique class of materials that merge the properties of organic and inorganic building blocks. These materials are at the frontier of material science due to their wide modularity and applicability in numerous fields, ranging from catalysis to nuclear waste treatment. Unprecedented tunability of physical properties via changes in organic, inorganic moieties and their connectivity, enables for hybrid materials to address current challenges in the materials’ applications improving energy landscape.

The presented work consists of six chapters where the synthesis and design of new hybrid materials, fundamental understanding of electronic behavior and its modulation in organic-inorganic materials, …

Advances In Chalcogenide Crystal Growth, Anna Berseneva

Theses and Dissertations

Chalcogenides are the cornerstone of the semiconductor and thermoelectric industries and are up-and-coming materials for superconductors, catalysis, and battery applications. Challenges in the synthesis of those materials emerge from the chalcogen’s volatility and the tendencies of chalcogenide to react with even trace quantities of oxygen. Nonetheless, many techniques have been applied to the growth of chalcogenide single crystals, which are convenient for structure determinations and intrinsic property measurements. This dissertation will detail synthetic strategies applied to the crystal growth of novel chalcogenide materials via molten flux preparation (Chapters 2, 4, and 5), hydrothermal synthesis (Chapter 1 and 3), and single-crystal-to-single …

Deconvolving Provenance Signatures Of Pliocene-Pleistocene Coastal Loess Deposits Along The Atlantic Margin Of Argentina, Will Robert Quanrud

Theses and Dissertations

Dust derived from southern South America provides critical nutrients for autotropic marine biota in the South Atlantic Ocean, such that fluxes of wind-blown sediment may ultimately affect the concentration of atmospheric CO2. Expansive sand, silt, and loess deposits are exposed in Central Argentina, recording millions of years of eolian processes; however, the provenance and transport pathways of this dust remains unclear. Coastal loess deposits ranging in age from Pliocene to upper Pleistocene are present along the Atlantic margin of Argentina and provide information on sediment transport pathways for the last 4 million years. Nine samples of loess were collected and …

Macro–Micro-Coupled Simulations Of Bead–Spring Breaking-Reforming Networks, Andrei Medved

Theses and Dissertations

In this work we investigate the dynamic behavior of bead-spring polymer solutions in viscoelastic fluids, which are essential in industries like materials science, biotechnology, and pharmaceuticals. The study leverages GPU-accelerated simulations and detailed modeling of polymer chain dynamics at the mesoscale, which enables efficient analysis of intricate fluid behaviors and the microscale dynamics of polymer chains. Additionally, the research examines the breaking-reforming dynamics of polymer chains, crucial for understanding phenomena such as shear thinning and thickening. The findings have broad applications, from improving inkjet printing and 3D printing technologies to developing new drug delivery systems and biocompatible materials. This work …

Bayesian Methods In Analyzing The Diagnostic Accuracy\\ For Ordinal Ratings, Yun Yang

Theses and Dissertations

This dissertation focuses on ordinal classification ratings, which are commonly used in medical practice to assess the severity of a disease or condition. For example, a group of radiologists rate a set of mammograms and assign BI-RADS (Breast Imaging Reporting Data System) score for each mammogram. A Bayesian probit hierarchical model is first proposed to analyze this type of data. It links the ordinal ratings with both rater diagnostic skills and patient latent disease severity. Each rater diagnostic skills are quantified with two parameters, diagnostic bias and diagnostic magnifier. Patient latent disease severity is assumed to follow a different normal …

Object Classification, Detection And Tracking In Challenging Underwater Environment, Md Modasshir

Theses and Dissertations

The main contributions of this thesis is the applicability and architectural designs of deep learning algorithms in underwater imagery. In recent times, deep learning techniques for object classification and detection have achieved exceptional levels of accuracy that surpass human capabilities. However, the effectiveness of these techniques in underwater environments has not been thoroughly researched. This thesis delves into various research areas related to underwater environments, such as object classification, detection, semantic segmentation, pose regression, and semi-supervised retraining of detection models.

The first part of the thesis studies image classification and detection. Image classification is a fundamental process that involves assigning …

Generalizations Of The Graham-Pollak Tree Theorem, Gabrielle Anne Tauscheck

Theses and Dissertations

Graham and Pollak showed in 1971 that the determinant of a tree’s distance matrix depends only on its number of vertices, and, in particular, it is always nonzero. This dissertation will generalize their result via two different directions: Steiner distance k-matrices and distance critical graphs. The Steiner distance of a collection of k vertices in a graph is the fewest number of edges in any connected subgraph containing those vertices; for k = 2, this reduces to the ordinary definition of graphical distance. Here, we show that the hyperdeterminant of the Steiner distance k-matrix is always zero if …

Representation Dimensions Of Algebraic Tori And Symmetric Ranks Of G-Lattices, Jason Bailey Heath

Theses and Dissertations

Algebraic tori over a field k are special examples of affine group schemes over k, such as the multiplicative group of the field or the unit circle. Any algebraic torus can be embedded into the group of invertible n x n matrices with entries in k for some n, and the smallest such n is called the representation dimension of that torus. Representation dimensions of algebraic tori can be studied via symmetric ranks of G-lattices. A G-lattice L is a group isomorphic to the additive group Zⁿ for some n, along with an action …

Metal-Organic Frameworks For Global Environmental Challenges, Kyoungchul Park

Theses and Dissertations

Over the past few decades, there has been a demand for improving nuclear waste administration due to a significant increase in the utilization of nuclear energy. The driving force for proper nuclear waste disposal is evident when considering past nuclear catastrophes—such as Chernobyl and Fukushima—where radionuclide contamination of large bodies of water sparked public concern. In order to manage such radioactive species, the emerging areas of radionuclide sequestration, storage, separation, and sensing must be addressed in the upcoming years. This dissertation presents a potential candidate for addressing these challenges, called metal-organic frameworks (MOFs). Due to their porosity, high surface area, …

Molecular Rotors For Quantifying Kinetic Effects Of Stabilizing Non-Covalent Interactions, Binzhou Lin

Theses and Dissertations

This thesis describes the development of molecular machines as analytical instruments to measure the strength of non-covalent interactions and to test hypotheses of reaction mechanisms. The first chapter is a review of molecular rotors. The second chapter presents the development of a molecular rotor that can be controlled using electrostatic interactions. Previous examples have used electrostatic interactions to slow down or inhibit molecular motion. Our system is activated and sped up using electrostatic interactions. The third and fourth chapters describe the application of molecular rotors designed to experimentally measure the strength and stability trends for non-covalent pnictogen and chalcogen interactions. …

One-Dimensional Cores Of Peano Continua, Shogo Starr

Theses and Dissertations

In this paper, we define a berbering of a Peano continuum, which is the space one gets by attaching a null sequence of circles to a countable dense subset of a Peano continuum. The topology of a berbering is one that recognizes which circles are small, in the sense that any neighborhood of the original Peano continuum will entirely contain all but finitely many of the attached circles. We then show that given a berbering of any simply connected, locally simply connected Peano continuum $Y$, there exists a one-dimensional Peano continuum $X$ and a map from $X$ to the berbering …

On Parallelization Of Graph Algorithms, Performance Modelling And Autonomous 3d Printable Object Synthesis, Shams-Ul-Haq Syed

Theses and Dissertations

The degree of hardware level parallelism offered by today’s GPU architecture makes it ideal for problem domains with massive inherent parallelism potential, fields such as computer vision, image processing, graph theory and graph computations. We have identified three problem areas for purpose of this research dissertation, under the umbrella of performance improvement by harnessing the power of GPUs for novel applications. The first area is concerned with k-vertex connectivity in graph theory, the second area deals performance evaluation using extended roofline models for GPU parallel applications and finally the third problem area is related to synthesis 3D printable objects from …

Exiting Inflation With A Smooth Scale Factor, Harry Oslislo

Theses and Dissertations

The expectation that the physical expansion of space occurs smoothly may be expressed mathematically as a requirement for continuity in the time derivative of the metric scale factor of the Friedmann–Robertson–Walker cosmology. We explore the consequences of imposing such a smoothness requirement, examining the forms of possible interpolating functions between the end of inflation and subsequent radiation- or matter-dominated eras, using a straightforward geometric model of the interpolating behavior. We quantify the magnitude of the cusp found in a direct transition from the end of slow roll inflation to the subsequent era, analyze the validity several smooth interpolator candidates, and …

Detection And Analysis Of Solid-Phase Nutrients In Complex Benthic Cyanobacterium Communities, Cassidy Ann Crandell

Theses and Dissertations

Eutrophication is one of the most serious water quality issues affecting aquatic systems in the United States. Densely populated urban areas as well as mining and agriculture are major sources of anthropogenic nutrient loading into lakes and rivers. Excess loading of nutrients like phosphorus (P) into these ecosystems can cause native algal species to be outcompeted by harmful algal bloom (HAB) species. Increases in these HAB events are a growing public health concern as contact with excreted toxins can be harmful for human, aquatic, and land species. Remediation techniques like total maximum daily loads (TMDLs) have been implemented to reduce …

Investigating Arctic Ocean Freshwater Content And Circulation In A Changing Climate, Emma Louise Hoffman

Theses and Dissertations

The Arctic Ocean is unique among the world’s oceans, characterized by its cold temperatures, salinity-driven vertical structure, and shallow shelf seas. It has warmed intensely since the 1980s at rates exceeding the global average. This Arctic Amplification drives variability in sea ice and salinity, affecting local circulation and exchange with other basins, leading to global changes in oceanic and atmospheric circulation and the biosphere. This thesis explores changing dynamics in the Arctic Ocean, in particular connecting modeled changes in liquid freshwater content (FWC) and its pathways with major ocean circulation patterns, atmospheric drivers, and large-scale climatic changes.

This research combines …

Statistical Inference Based On Elliptically Symmetric Distributions For Directional Data, Zehao Yu

Theses and Dissertations

Directional data arise in many scientific fields such as meteorology, oceanography, geology, zoology, and biomechanics. Geometrically, directional data lie in a spherical space. Although not in a spherical space, compositional data, such as microbiome data, can be mapped from a simplex to a spherical space via the component-wise square-root transformation. Other examples where compositional data emerge as a subject of interest include compositions of minerals in rocks, compositions of chemical mixtures, investment portfolios, and demographic composition of a population. This dissertation aims to develop inference procedures for analyzing directional data in general initially, with later focus shifted to the transformed …

Molecular And Hybrid Catalysts For Selective Hydrodeoxygenation Of Lignin Model Compounds, Jacob G. Tillou

Theses and Dissertations

Lignin is a highly aromatic, branched polymer and could be utilized as a renewable source of liquid fuel. The advent of “lignin-first” depolymerization processes have allowed for the high-yield isolation of oxygenated aromatic monomers from lignin. These oxygenated aromatic compounds are lower in energy and stability than their deoxygenated counterparts. Selective deoxygenation of these compounds would result in stable, higher value liquid fuels. Using molecular catalysts, selective deoxygenation, or hydrodeoxygenation (HDO), of lignin-derived compounds in the presence of hydrogen is possible.

Immobilization of these molecular catalysts on metal oxide surfaces eliminates the possibility of bimolecular decomposition and allows for easier …

Erlang-Distributed Seir Epidemic Models With Cross-Diffusion, Victoria Chebotaeva

Theses and Dissertations

We examine the effects of cross-diffusion dynamics in epidemiological models. Using reaction-diffusion dynamics to model the spread of infectious diseases, we focus on situations in which the movement of individuals is affected by the concentration of individuals of other categories. In particular, we present a model where susceptible individuals move away from large concentrations of infected and infectious individuals.

Our results show that accounting for this cross-diffusion dynamics leads to a noticeable effect on epidemic dynamics. It is noteworthy that this leads to a delay in the onset of epidemics and an increase in the total number of people infected. …