Physical Sciences and Mathematics Commons^™

Rainfall Accumulation In Clarksville, Tennessee 2015093 To 2015121, Jessica Mae Bender

Graduate Student Publications and Other Works

The purpose of this project was to collect rainfall samples and record the data in such a way that tested a hypothesis. My hypothesis is that the area in Clarksville, Tennessee where the samples are collected will collect up to eight inches of rain for the thirteen week time span.

Methodology For Generating Simplified Cross Section Data Sets For Neutron Transport Calculations, Thomas Jay Harrison

Doctoral Dissertations

Neutron shielding problems involve radiation transport calculations over a wide range of energies. Fission neutrons have initial energy on the order of MeV, fusion neutrons have initial energy on the order of 10s of MeV, and space-origin neutrons have initial energy on the order of 100s of MeV or higher. Shielding calculations must track the neutrons from their initial energies until they are no longer of interest; for deep-penetration neutrons, this final energy can be on the order of eV before the neutron is no longer tracked. Thus, for deep-penetration space radiation shielding problems, the calculation may require tracking the …

Understanding The Influence Of Non-Covalent Interactions And Nanoparticle Geometries In Carbon Based Polymer Nanocomposites, Bradley Carroll Miller

Doctoral Dissertations

Low-loading polymer nanocomposites (PNC) are an area of great interest in polymer science. As nanoparticles (NP) are typically expensive in comparison to matrix materials; the low loading regime makes the most efficient use of materials, and represents the optimum for realizing cost effective, high-performance PNCs. However, formulating effective low-loading composites is not without challenges. In addition to the typical requirement of good dispersion for efficient translation of NP properties to the bulk, low-loading composites can sometimes exhibit anomalous (non-classical) dynamics, and unpredictable properties. It is within this context that this thesis aims to examine the effects of NP geometry and …

Rare Earth Production And Characterization Studies, Jake Anson Stewart

Doctoral Dissertations

The rare earths include elements Sc, Y, and La through Lu are important in many modern technologies. With the exception of Sc and Ce the rare earths are all have similar chemical behaviors with the preferred oxidation state in aqueous solution being +3. Currently, industrial purification of the rare earths is completed by counter current solvent extraction (CCSX). In most CCSX separations, Y extracts with Ho making their separation difficult. However, in a few systems Y exhibits an itinerant behavior. Carboxylic acids of varying sizes and substitutions were investigated in a study of Y itinerant behavior. It was found when …

Spontaneously Generated Inhomogeneous Phases Via Holography, Kübra Yeter Aydeniz

Doctoral Dissertations

We discuss a holographic model consisting of a U(1) gauge field and a scalar field coupled to a charged AdS (anti-de Sitter) black hole under a spatially homogeneous chemical potential. By turning on a higher-derivative interaction term between the U(1) gauge field and the scalar field, a spatially dependent profile of the scalar field is generated spontaneously. We calculate the critical temperature at which the transition to the inhomogeneous phase occurs for various values of the parameters of the system. We solve the equations of motion below the critical temperature, and show that the dual gauge theory on the boundary …

Interface And Morphology Engineering In Solution-Processed Electronic And Optoelectronic Devices, Sanjib Das

Doctoral Dissertations

The first part of this dissertation focuses on interface and morphology engineering in polymer- and small molecule-based organic solar cells. High-performance devices were fabricated, and the device performance was correlated with nanoscale structures using various electrical, spectroscopic and microscopic characterization techniques, providing guidelines for high-efficiency cell design.

The second part focuses on perovskite solar cells (PSCs), an emerging photovoltaic technology with skyrocketing rise in power conversion efficiency (PCE) and currently showing comparable PCEs with those of existing thin film photovoltaic technologies such as CIGS and CdTe. Fabrication of large-area PSCs without compromising reproducibility and device PCE requires formation of dense, …

Solution And Surface Properties Of Architecturally- And Compositionally-Complex Block Copolymers And Their Binary Mixtures, Jesse Lawrence Davis

Doctoral Dissertations

The spontaneous generation of complex structures from polymeric building blocks provides a simple yet effective route to create useful soft matter structures having potential application in a variety of nanotechnologies. The topology, chemical structure, block composition, and sequence of the constituent building blocks of polymers are tunable through synthetic chemistry. This tunability offers attractive opportunities to generate complex, yet well-defined structures with control over the geometry, packing symmetry, and microdomain structure. This thesis work involves the study of the self-assembly behaviors of architecturally complex amphiphilic block copolymers (ABCs). ABCs are composed of two or more chemically distinct blocks that are …

Effective Field Theory Approach To Collective Motion In Atomic Nuclei, Eduardo Antonio Coello Perez

Doctoral Dissertations

Collective motion in heavy nuclei has been studied within collective and algebraic models, and within density functional theory. While they reproduce the energy spectra of these systems, their predictions for some electromagnetic transitions and moments do not lie within experimental uncertainty; in other words, these predictions are inconsistent with experimental data. An effective field theory approach to collective motion in heavy nuclei solves this long standing problem. Based on symmetry arguments only, the effective field theories, constructed as expansions in powers of a small parameter, consistently describe the energy spectra of nuclei exhibiting collective motion at low order in the …

Solar Modulation Of The Cosmic Ray Intensity And The Measurement Of The Cerenkov Reemission In Nova’S Liquid Scintillator, Philip James Mason

Doctoral Dissertations

The NOνA (NuMI Off-axis electron neutrino Appearance) experiment is a long baseline neutrino oscillation experiment at Fermi National Accelerator Laboratory. Its purpose is to observe the oscillation of ν_μ (muon neutrino) to ν_e (electron neutrino) and to investigate the neutrino mass hierarchy and CP violation in the neutrino sector. Two detectors have been built for this purpose, a Near Detector 300 feet underground at Fermilab, and a Far Detector, on the surface at Ash River, Minnesota.

The completion of NOνA’s Far Detector in October 2014 enabled not only the recent measurement of neutrino oscillations, but an array of …

Computational Simulation Of Mass Transport And Energy Transfer In The Microbial Fuel Cell System, Shiqi Ou

Doctoral Dissertations

This doctoral dissertation introduces the research in the computational modeling and simulation for the microbial fuel cell (MFC) system which is a bio-electrochemical system that drives a current by using bacteria and mimicking bacterial interactions found in nature. The numerical methods, research approaches and simulation comparison with the experiments in the microbial fuel cells are described; the analysis and evaluation for the model methods and results that I have achieved are presented in this dissertation.

The development of the renewable energy has been a hot topic, and scientists have been focusing on the microbial fuel cell, which is an environmentally-friendly …

Neuron Clustering For Mitigating Catastrophic Forgetting In Supervised And Reinforcement Learning, Benjamin Frederick Goodrich

Doctoral Dissertations

Neural networks have had many great successes in recent years, particularly with the advent of deep learning and many novel training techniques. One issue that has affected neural networks and prevented them from performing well in more realistic online environments is that of catastrophic forgetting. Catastrophic forgetting affects supervised learning systems when input samples are temporally correlated or are non-stationary. However, most real-world problems are non-stationary in nature, resulting in prolonged periods of time separating inputs drawn from different regions of the input space.

Reinforcement learning represents a worst-case scenario when it comes to precipitating catastrophic forgetting in neural networks. …

Algorithm-Based Fault Tolerance For Two-Sided Dense Matrix Factorizations, Yulu Jia

Doctoral Dissertations

The mean time between failure (MTBF) of large supercomputers is decreasing, and future exascale computers are expected to have a MTBF of around 30 minutes. Therefore, it is urgent to prepare important algorithms for future machines with such a short MTBF. Eigenvalue problems (EVP) and singular value problems (SVP) are common in engineering and scientific research. Solving EVP and SVP numerically involves two-sided matrix factorizations: the Hessenberg reduction, the tridiagonal reduction, and the bidiagonal reduction. These three factorizations are computation intensive, and have long running times. They are prone to suffer from computer failures.

We designed algorithm-based fault tolerant (ABFT) …

Novel Thermoplastic Elastomers Based On Benzofulvene: Synthesis And Mechanical Properties, Weiyu Wang

Doctoral Dissertations

Thermoplastic elastomers (TPEs) are of great importance both academically and technologically. Currently TPEs are the predominated form of styrene-diene copolymers. However, these styrenic TPEs have serious limitations in applications, especially at higher temperature, because of their low upper service temperature (UST). The work described in this dissertation aimed to developing thermoplastic elastomers with a higher UST and lower cost.

In order to develop TPEs with a higher UST, we employed benzofulvene, an anionically polymerizable monomer in hydrocarbon solvent at room temperature, as the glassy block and copolymerized it with isoprene to prepare polybenzofulvene-polyisoprene-polybenzofulvene (FIF) triblock copolymers. Among all triblock copolymers …

All-Acrylic Multigraft Copolymers: Synthesis And Structure-Property Relationship For Producing Next Generation Thermoplastic Elastomers, Andrew Brown Goodwin

Doctoral Dissertations

Polymer architecture and the advancement of molecular design using anionic and other controlled polymerization methods continues to be of significant research interest because of the tunable approach it provides, which can impact numerous applications ranging from thermoplastics to drug delivery systems. Among the numerous branched structures currently investigated, comb and graft copolymers continue to provide tailored materials which exhibit superior mechanical properties when compared to their di- and triblock linear counterparts. More specifically, the incorporation of two or more monomers into graft and multigraft constructions where the side chains are composed of a plastic (high T_g [glass transition temperature]) …

The Effect Of Composition And Architecture On Polymer Behavior In Homopolymer Blends And Inter-Filament Bonding In 3d Printed Models, Edward Roy Duranty

Doctoral Dissertations

This dissertation presents work that increases our understanding of the effects of composition and architecture on copolymer structure and dynamics and how they affect material diffusion between filaments in a 3D printed model. Copolymers are polymer chains made up of at least two different monomers. The ordering and arrangement of the two monomer species within a copolymer can have drastic effects on the behavior and properties of the copolymer.

The first chapter of this dissertation examines how the copolymer composition affects the structure and dynamics of the chain in a homopolymer blend. This study used a modified Monte Carlo BFM …

Batched Linear Algebra Problems On Gpu Accelerators, Tingxing Dong

Doctoral Dissertations

The emergence of multicore and heterogeneous architectures requires many linear algebra algorithms to be redesigned to take advantage of the accelerators, such as GPUs. A particularly challenging class of problems, arising in numerous applications, involves the use of linear algebra operations on many small-sized matrices. The size of these matrices is usually the same, up to a few hundred. The number of them can be thousands, even millions.

Compared to large matrix problems with more data parallel computation that are well suited on GPUs, the challenges of small matrix problems lie in the low computing intensity, the large sequential operation …

Bacterial Diversity And Function Within An Epigenic Cave System And Implications For Other Limestone Cave Systems, Kathleen Merritt Brannen-Donnelly

Doctoral Dissertations

There are approximately 48,000 known cave systems in the United States of America, with caves formed in carbonate karst terrains being the most common. Epigenic systems develop from the downward flow of meteoric water through carbonate bedrock and the solutional enlargement of interconnected subsurface conduits. Despite carbonate karst aquifers being globally extensive and important drinking water sources, microbial diversity and function are poorly understood compared to other Earth environments. After several decades of research, studies have shown that microorganisms in caves affect water quality, rates of carbonate dissolution and precipitation, and ecosystem nutrition through organic matter cycling. However, limited prior …

Grouping Digits As A Method For Increasing Computation Speed Of Galois Field Arithmetic For Erasure Coding Applications, John Andrew Burnum

Haslam Scholars Projects

The performance of multiplications in Galois Field arithmetic using the GROUP method is measured, described, and analyzed using the GF Complete open-source library. Galois Field arithmetic is vital for many erasure coding methods, including Reed-Solomon coding, and the GROUP method is a simple and modular technique for increasing computation speed.

Testing For The Effects Of Sediment Sorting On Detrital-Zircon Age Spectra By Sampling Multiple Bedforms In Single Fluvial Channels: Case Studies From The Wood Canyon Formation (Terreneuvian) And Stirling Quartzite (Ediacaran), Southeastern Ca, Jason Gerhard Muhlbauer

Masters Theses

Multiple bedforms were sampled from single fluvial channels in the Neoproterozoic (Ediacaran) upper member of the Stirling Quartzite and the Cambrian (Terreneuvian) middle member of the Wood Canyon Formation, southeastern California. Sampling strategy was designed to determine if sorting of detrital zircon populations by their textural properties can affect detrital-zircon age spectra in fluvial sandstones. Four samples derive from the middle member Wood Canyon Formation and two samples come from the upper member Stirling Quartzite. Sandstone samples vary in textural characteristics: grain sizes sampled range from fine to coarse sand, sorting ranges from moderately well to poorly sorted, and sampled …

Late Tertiary Tectonic Uplift In The Southern And Central Appalachians, Mary Sheela Biswal

Masters Theses

The exposed Appalachian Mountains extend about 2500 km from Newfoundland to Alabama with the highest peaks >2000 m above sea level. The last orogeny that affected Appalachian crust was the 325-260 Ma Alleghanian. Even with minimal erosion rates, it is highly unlikely that the Appalachians could have sustained such elevations for over 200 m.y., suggesting that recent tectonic uplift has produced today’s mountainous topography. The multiple phases of Tertiary uplift are related to poorly understood processes, but a large amount of data from today’s mountain chain and the adjacent Coastal Plain indicate the present high topography is anomalous and clearly …

Hsp-Wrap: The Design And Evaluation Of Reusable Parallelism For A Subclass Of Data-Intensive Applications, Paul R. Giblock

Masters Theses

There is an increasing gap between the rate at which data is generated by scientific and non-scientific fields and the rate at which data can be processed by available computing resources. In this paper, we introduce the fields of Bioinformatics and Cheminformatics; two fields where big data has become a problem due to continuing advances in the technologies that drives these fields: such as gene sequencing and small ligand exploration. We introduce high performance computing as a means to process this growing base of data in order to facilitate knowledge discovery. We enumerate goals of the project including reusability, efficiency, …

Rapid Dissolution For Destructive Assay Of Nuclear Melt Glass, Jonathan Allen Gill

Masters Theses

This study evaluates four methods for dissolving complex glassy debris resulting from nuclear detonations. The samples of interest simulate the glassy debris generated from a nuclear detonation’s fireball coming in contact with solid masses. Each method attempts to achieve dissolution through different approaches involving either acid digestion, alkaline digestion, or molten salt fusion. Two of the four methods were modified to retain all elements of the debris or surrogate debris. This retention is critical to the proportional relationships used in identifying fuel types and designs of nuclear weapons. Analysis is conducted with an inductively coupled time of flight mass spectrometer …

Siloxane And Silane-Functionalized Polynorbornenes As Membranes For Passive Carbon Dioxide Separation, Eunice Koheun Hong

Masters Theses

In 2012, carbon dioxide (CO₂) [carbon dioxide] accounted for approximately 82% [percent] of all U.S greenhouse gas emissions.¹ These excessive CO2 levels have been attributed to climate changes that have a range of negative effects on human health and welfare.1 In an effort to decrease these emissions, polymeric membranes consisting of silane- and siloxane-functionalized norbornene units have been targeted as a potential solution for the passive separation of CO2 from other non-greenhouse gases. These substituted norbornene-based polymers were synthesized via vinyl-addition polymerization. Through a series of catalyst trials, commercially available palladium and nickel catalysts were compared along …

Border-Collision Bifurcations Of Cardiac Calcium Cycling, Jacob Michael Kahle

Masters Theses

In this thesis, we study the nonlinear dynamics of calcium cycling within a cardiac cell. We develop piecewise smooth mapping models to describe intracellular calcium cycling in cardiac myocyte. Then, border-collision bifurcations that arise in these piecewise maps are investigated. These studies are carried out using both one-dimensional and two-dimensional models. Studies in this work lead to interesting insights on the stability of cardiac dynamics, suggesting possible mechanisms for cardiac alternans. Alternans is the precursor of sudden cardiac arrests, a leading cause of death in the United States.

Installation And Alignment Of The N3he Experiment, Eric Lee Plemons

Masters Theses

The n3He experiment is designed to probe the hadronic weak interaction by measuring the parity violating asymmetry between the spin of incoming neutrons and the momentum of outgoing protons following the nuclear break up of a helium three upon absorbing a neutron. Cold neutrons from the SNS are first polarized then allowed to impact a target chamber filled with helium three where the reaction occurs. Energetic particles resulting from the nuclear breakup ionize the helium three gas and are thereby detected as currents by an array of signal wires within the target chamber. In order to make a statistics limited …

Rare Occurrences Of Free-Living Bacteria Belonging To Sedimenticola From Subtidal Seagrass Beds Associated With The Lucinid Clam, Stewartia Floridana, Aaron M. Goemann

Masters Theses

Lucinid clams and their sulfur-oxidizing endosymbionts comprise two compartments of a three-stage, biogeochemical relationship among the clams, seagrasses, and microbial communities in marine sediments. A population of the lucinid clam, Stewartia floridana, was sampled from a subtidal seagrass bed at Bokeelia Island Seaport in Florida to test the hypotheses: (1) S. floridana, like other lucinids, are more abundant in seagrass beds than bare sediments; (2) S. floridana gill microbiomes are dominated by one bacterial operational taxonomic unit (OTU) at a sequence similarity threshold level of 97% (a common cutoff for species level taxonomy) from 16S rRNA genes; …

Preparation And Characterization Of Thermodynamically Controlled Polymer Nanocomposites, Jiadi Hou

Masters Theses

The mechanical and physical properties of polymeric materials can be greatly improved by adding nanoscale additives. To mediate the dispersion of nanoparticles in polymers, it is often necessary to modify their surfaces to prevent aggregation. While polymer nanocomposites system consisting of homopolymer-grafted nanoparticles are well understood, copolymer-functionalized nanoparticles are less well understood but provide additional ways to alter dispersion through the use of chemically different comonomers. In this thesis, polystyrene nanocomposites blended with copolymer-grafted nanoparticles were prepared and studied. The particular comonomers used were methyl methacrylate and cyclohexyl methacrylate, which provides miscibility with polystyrene. Polymers with varying comonomer ratios were …

Chemical Investigations Of Diabetes Mellitus, Malaria, And Castrate-Resistant Prostate Cancer, Maggie Sparks Lookadoo

Masters Theses

This work studies a variety of molecules and the systems they are involved in to further understand disease and treatment of diabetes mellitus, malaria, and castrate resistant prostate cancer. The first system studied, diabetes mellitus, involves synthesis of 5 different steroidal compounds, while the other two systems, malaria and castrate-resistant prostate cancer, apply mass spectrometric-based untargeted metabolomics to study both known metabolites and unknown spectral features.

Diabetes mellitus is a result of the dysfunction and death of islet beta cells caused by the transcription of pro-inflammatory cytokines resulting in reduced insulin secretion and uncontrollable blood glucose levels. Glucocorticoids can reduce …

Determination Of Dispersal Patterns And Characterization Of Important Habitats For Lake Sturgeon Restoration In The Upper Tennessee River System, Christina Grace Saidak

Masters Theses

Lake Sturgeon, Acipenser fulvescens, are one of the slowest to reach sexual maturity and longest-lived freshwater fish species in North America. These fish are a species of special concern by the U.S. Fish and Wildlife Service, a vulnerable species by the American Fisheries Society (Jelks et al. 2008), and a threatened species in Tennessee (Chiasson et al. 1997; Williams et al. 1989). They have been reintroduced into the Upper Tennessee River system since 2000.

Since December 2013, 49 Lake Sturgeon have been implanted with ultrasonic acoustic transmitters, and 26 fixed-station receivers installed throughout the Upper Tennessee River System to …

Neutrino Signatures In Terrestrial Detectors From Two- And Three-Dimensional Core-Collapse Supernovae Simulations, Tanner Brooks Devotie

Masters Theses

Core-collapse supernovae (CCSNe) are driven by neutrino emission and are the most prodigious sources of neutrinos in the Universe. Importantly, the neutrino radiation from CCSNe is emitted from deep in the explosion and can provide information about physical processes taking place in the newly-born neutron star at the heart of the event. We examine the four-flavor (i.e. ν_e, ν_e, ν_x and ν_x) [electron, muon and tau neutrinos along with their anti-matter counterparts] signature of CCSNe neutrino emission in various neutrino detector types. We use data from the multidimensional Chimera (Lentz et al., 2015) …