Digital Commons Network^™

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 …

Unraveling The Structure And Star Formation History Of Polar Ring Galaxies, Kyle Lackey

Theses and Dissertations

Polar ring galaxies (PRGs) are a fascinating subgroup of early-type galaxies (ETGs) consisting of a central host galaxy - typically E/S0 - surrounded by a ring of gas, dust and stars orbitting perpedicular to the major axis of that host. In order to estimate physical properties and origins of five such objects taken from Whitmore's 1990 PRC catalog, we conduct a photometric study in optical and infrared wavebands. Data are taken from SDSS, GMOS-S, HST-WFPC2, and SST-IRAC. Each object was decomposed into a host galaxy bulge, host galaxy disk, and polar ring, and each component was fit with a Sersic …

Predictive Models Of Polymer Composites: A Thesis, Navid Afrasiabian

Electronic Thesis and Dissertation Repository

Predictive models are a powerful tool to understand and improve physical systems. Predictive models not only can be used to improve current materials, but they also gain fundamental understanding of the underlying processes. There are numerous theoretical and numerical models introduced in the field of polymer composites and nanocomposites. Different methods best describe a system at a specific time and length scale. In this thesis, I utilize Coarse-grained Molecular Dynamics (CGMD), Multi-PhaseField (MPF), and Lattice-Boltzmann (LB) methods to study different aspect of polymer composites and nanocomposites.

Starting at the nanoscale, we study the dispersion and orientation patterns of nanorod-polymer systems …

Maximizing Legged Accelerations: A Matter Of Force, Time, And Gravity, Lance Brooks

Applied Physiology and Wellness Theses and Dissertations

Sprint running accelerations require runners to apply surface forces that: support body weight by pushing downward, accelerate the body horizontally by pushing backward, and align the direction of the push with the body’s mass center to maintain balance and posture, which imposes an upper limit on the average forward acceleration force equal to the average gravitational force (1.0 G) acting on the runner. This expectation arises from the mechanical constraints imposed by the need to generate sufficient vertical force to support body weight against gravity while simultaneously producing horizontal force to accelerate forward and aligning the push through the center …

Constraints On Solar Axions Using The Profile Likelihood Ratio Method With The Supercdms Experiments, Shilun Liu

Physics Theses and Dissertations

Dark matter plays an essential role in understanding modern physics and particles beyond the Standard Model. Evidence suggests that dark matter accounts for approximately 85% of the universe’s matter, and 26.8% of its mass-energy composition. Key candidates for dark matter include unidentified subatomic particles like Weakly Interacting Massive Particles (WIMPs) and axions. The Super Cryogenic Dark Matter Search (SuperCDMS) employs direct detection methods to identify these elusive particles using cryogenic technologies. Su- perCDMS Soudan is the latest completed CDMS experiment in Minnesota, in preparation for the next phase experiments of SuperCDMS SNOLAB in Sudbury, Canada. At SNOLAB, the Cryogenic Underground …

On Weak Solutions And The Navier-Stokes Equations, Aryan Prabhudesai

Mathematical Sciences Undergraduate Honors Theses

In this paper, I will discuss a partial differential equation that has solutions that are discontinuous. This example motivates the need for distribution theory, which will provide an interpretation of what it means for a discontinuous function to be a “solution” to a PDE. Then I will give a detailed foundation of distributions, including the definition of the derivative of a distribution. Then I will introduce and give background on the Navier-Stokes equations. Following that, I will explain the Millennium Problem concerning global regularity for the Navier-Stokes equations and share mathematical results regarding weak solutions. Finally, I will go over …

Methods For Improving Low Frequency Selection And Electrode Firing Order In Cochlear Implants, James H. Keen Jr.

University of New Orleans Theses and Dissertations

The Advanced Bionics cochlear implant devices allocate static frequency bins to electrode channels based on the natural tonotopic organization of the cochlea. These frequency bins are wide and limited, especially in the lower range. Considering that the fundamental tones of the human voice and the primary melodic tones in music are in this lower range, it is important to have accurate representation of this frequency content. Here, adjustments to the frequency bin allocation algorithm used in the crowdsourced CI Hackathon code are made to allow a more accurate representation of the original signal. First, the frequency bins allocated to each …

Investigation Of Optically Pumped Gesn Quantum Well Lasers, Grey Steven Abernathy

Graduate Theses and Dissertations

Silicon photonic integrated circuits enable the capability of producing on-chip processing of photonic signals, including both emission and detection. Emission materials, however, have been limited for monolithic integration due to high processing temperatures, indirect bandgap materials, and material integration complications. The (Si)GeSn material system has recently attracted attention due to the bandgap transition from the Si and Ge, naturally indirect bandgap, to direct bandgap with sufficient Sn incorporation. Additionally, the low growth temperature (CMOS compatible; <400 >°C) of (Si)GeSn materials can enable the monolithic integration of the highly desired mid-infrared light emission on the Si Photonic platform. This dissertation first discusses …

Understanding And Control Of Frustration And Topological Defects In Ferroic Matter, Suyash Rijal

Graduate Theses and Dissertations

Ferroic matter are of great importance as they provide a platform to extend the understanding of many-body physics and also for their amazing functional properties relevant for technological advancements. The work in this dissertation is dedicated to two of such ferroic materials. First is CrGeTe3 (CGT), a two dimensional (2D) magnet discovered in 2017. The discovery of two-dimensional magnetism has invigorated the research community as their low dimensionality offers a unique avenue to understand and investigate the origin of magnetism in these atomically thin systems and harvest diverse application such as information processing, storage and transfer using their magnetic spins. …

3d-Magnetometer Arrays In Physics Experiments, Shaun G. Vavra

Masters Theses

This study presents the design and experimental evaluation of a magnetometer array utilizing LIS3MDL chips integrated with an Arduino microcontroller. Magnetometer arrays find crucial applications in various fields, including physics research, geophysics, and navigation systems. The goal of this research is to create an affordable and versatile magnetometer array for scientific investigations and practical applications. The paper begins by outlining the hardware and software components of the array. The LIS3MDL chips, known for their high sensitivity and low power consumption, are employed as the core sensing elements. The Arduino microcontroller is utilized for data acquisition and processing. The integration of …

Electroweak Interactions On The Deuteron, Jose Luis Bonilla

Doctoral Dissertations

This research explores the intricacies of Electroweak Interactions on the Deuteron, with a particular focus on muon capture and the hyperfine shift in atomic and muonic deuterium. These processes are phenomena of significant importance in nuclear physics. Understanding these interactions is crucial for illuminating fundamental aspects of nuclear structure and providing insight into the fundamental forces and interactions governing atomic and nuclear systems, as well as related processes such as proton-proton fusion or other astrophysical reactions, which are phenomena that cannot be easily reproduced in a laboratory and require a theoretical treatment to predict observables. Through this research, we systematically …

Investigation Of Seasonal Trends And Source Apportionment Of Particulate Matter (Pm2.5) In El Paso-Juarez Airshed, Fatema Tuz Zohora

Open Access Theses & Dissertations

Using the data from Texas Commission on Environmental Quality (TCEQ) for the El Paso city throughout the years from 2021 to 2024 Particulate Matter (PM2.5) was measured to examine the seasonal distribution and sources. This study aims to understand the seasonal variability of PM2.5 concentrations, identify the significant impact of wildfire events on this and source apportionment.The analysis begins with a comprehensive examination of PM2.5 data from TCEQ highlighting the seasonal pattern, it was found that fine particulate matter was more prevalent in winter and tends to be down in spring, and in summer it is relatively lower, subsequently in …

Determining Heterogeneous Growth Rates Of Brucite On Magnesia Using Multiharmonic Qcm-D And X-Ray Scattering Methods, Pedro Josue Hernandez Penagos

Open Access Theses & Dissertations

The Earth’s temperature has increased in the last six decades mainly due to the emissions of greenhouse gases, including carbon dioxide (CO2). Mineral looping using magnesium oxide (MgO) is a promising approach for direct air capture (DAC) of CO2 from the atmosphere at the GtCO2/yr scale. The presence of humidity during the carbonation process will lead to a reaction between the MgO and water resulting in magnesium hydroxide formation, Mg(OH)2, growing over the MgO surface forming a shell-like structure. The influence of temperature and relative humidity variation on heterogeneous nucleation and crystal growth kinetics of Mg(OH)2 on MgO is not …

Quantum Circuit Optimization Leveraging Multi-Qubit Exchange Interactions In Spin Qubits, Miguel Gonzalo Rodriguez

Open Access Theses & Dissertations

This thesis looks into how multi-qubit exchange interactions can be used to improve quantumcircuits in semiconductor quantum devices. Pairwise interactions between qubits are a common tenet of traditional quantum computing paradigms, although they can impose complexity and depth constraints on circuits. In order to improve the efficiency and scalability of quantum circuits, this research explores the theoretical underpinnings and practical uses of multi-qubit interactions. A thorough theoretical framework is formulated, outlining the mathematical equivalence of a unitary matrix representing interactions between multiple qubits. We obtain the timeevolution operator by analyzing the Hamiltonian of three spin-1/2 particles. A number of quantum …

2d Temperature Map Acquisition Using Hyperspectral Imaging System (Hsis), Anthony Kim

Masters Theses

Imaging techniques are close to our lives and are used for various applications. In the engineering field, one of the dominant techniques is hyperspectral imaging. It is a necessary tool that combines spectroscopy and digital photography and provides additional information on what is imaged by the imaging system. Hyperspectral imaging has been applied to various fields including remote sensing, cultural relic conservation, food microbiology, forensic science, biomedicine, etc.

In particular, work was done to apply hyperspectral imaging to measure the temperature and emissivity of an object. Due to its ability to measure temperature and emissivity without being in contact with …

Capillary Phenomena In Flow Down Fibers: Beads, Bridges, Sheets, And Threads, Chase Tyler Gabbard

All Dissertations

Capillary phenomena are ubiquitous in everyday life with surface tension responsible for shaping liquids and deforming slender structures on length scales smaller than the capillary length, as seen in the formation of drops from a leaky faucet and in the coalescence of wet hair, respectively. Recently, thin film flow down fibers have received significant attention for their ability to produce bead-on-fiber patterns with associated high surface area-to-volume ratios that optimize retention times in heat and mass transfer applications. The presence of a base flow gives rise to complex dynamics including absolute and convective instabilities. The parallelization of these processes through …

Pion, Kaon, And Proton Production In Jet-Hadron Correlations From Pb-Pb Collisions At $\Sqrt{S_{Nn}}$=5.02 Tev Using The Alice Detector, Patrick J. Steffanic

Doctoral Dissertations

Interactions between hard probes and the quark-gluon plasma (QGP) are a rich probe of the dynamics of the QGP. In this thesis, we study the production of pions, kaons and protons from jet-hadron correlations in 0-10% and 30-50% central Pb-Pb collisions at √s_NN = 5.02 TeV with the ALICE detector at the LHC. We focus our studies on low momentum jets with 20 GeV/c < p_T^jet < 40 GeV/c using associated hadrons with 1 GeV/c < p_T^assoc. < 10 GeV/c. The yields of associate pions, kaons and protons were measured in the near-side and away-side regions of the jet-hadron correlation function, and the baryon to meson and strange to non-strange meson ratios were computed. This is the first measurement of the strange to non-strange meson ratio for hadrons associated with a jet. We find the baryon to meson ratio for associated hadrons in Pb-Pb collisions to be within uncertainty of the ratio for inclusive charged hadrons in proton-proton collisions. The strange to non-strange meson ratio for associated hadrons in Pb-Pb collisions shows strong enhancement at intermediate p_T^assoc. relative to the ratio for inclusive charged hadrons in proton-proton collisions, with a hint of enhancement over the ratio for inclusive charged hadrons in Pb-Pb collisions. We find that …

Prompt Vs Local Redeposition: Model Refinement And Experimental Design For Understanding High-Z Net Erosion In Magnetic Confinement Fusion, Davis C. Easley

Doctoral Dissertations

The economic and engineering success of magnetic confinement fusion reactors significantly depends upon the optimization of plasma facing component (PFC) design. For high-Z PFCs, the critical engineering condition is minimal net erosion (i.e. gross erosion – redeposition). Here, we present a high-Z net erosion model discriminating three primary redeposition mechanisms: prompt (geometric-driven), local (sheath-driven), and far (scrape-off-layer-driven). Using these distinctions, we show modeling for high-Z net erosion in magnetic-confinement fusion over a matrix of key plasma parameters. With Sobol’ methods we assess the sensitivity of each mechanism and show that prompt-vs-local trade-off critically explains underprediction in redeposition losses of up …

Novel Quantum Algorithms For Noisy Intermediate-Scale Quantum (Nisq) Devices, Shikha Bangar

Doctoral Dissertations

Quantum computers hold the immense potential to revolutionize the current computing technology. However, the available quantum hardware, known as noisy intermediate-scale quantum (NISQ) devices, poses a challenge as these devices have noise and imperfect qubits. Hence, there is a critical need to develop novel algorithms specifically designed to harness the capabilities of these devices. This work aims to develop and optimize such quantum algorithms for implementation on current quantum technologies by integrating principles from physics and machine learning. First, we developed the Quantum Imaginary Time Evolution (QITE) and Quantum Lanczos (QLanczos) algorithms on discrete-variable quantum computing settings to study the …

Quantum Computing And Information For Nuclear Physics, Chenyi Gu

Doctoral Dissertations

Quantum computation and quantum information, hot topics with immense potential, are making exciting strides in nuclear physics. The computational complexity of nuclear physics problems often surpasses the capabilities of classical computers, but quantum computing offers a promising solution. My research delves into the application of quantum computation and quantum information in nuclear physics.

I am curious about how to approach nuclear physics problems on a quantum computer. This dissertation studies how to prepare quantum states with quantum algorithms, as state preparation is a crucial initial step in studying nuclear dynamics. Two different quantum algorithms are studied: (i) the time-dependent method, …

Astrophysics, Cosmology, And Fundamental Interactions With Gravitational Waves, Anarya Ray

Theses and Dissertations

Several unresolved mysteries remain in our understanding of the universe that can be elucidated with a growing catalog of gravitational wave~(GW) and multi-messenger observations of compact binary coalescences~(CBCs). Current and future catalogs, assisted by robust modeling and scalable inference frameworks, will lead to new insights into the poorly understood physics of compact binary formation, independent measurements of the cosmological expansion, and unprecedented empirical probes into the very nature of fundamental interactions. The scientific potential of GW observations from CBCs is significantly enhanced through the detection of their multi-messenger counterparts. Similarly, multi-probe explorations of compact object universal properties that combine GW …

Use Of Geomagnetic Paleointensity As A Correlation Tool In The Eastern Snake River Plain Lava Flows, Melissa Marie Sikes

Theses and Dissertations

The Snake River Plain volcanic province stretches 600 km from eastern Oregon across southern Idaho and into northwest Wyoming. Over the past ~14 million years, olivine tholeiitic lava flows have accumulated. To assess ongoing volcanic hazards, it is important to quantify the number, timing, and size of eruptive events. This assessment requires correlating lava flows across coreholes within the Eastern Snake River Plain. Previous paleomagnetic research applied paleomagnetic inclinations to correlate flows between coreholes. This study tests whether using geomagnetic paleointensity – in addition to inclination – can increase confidence in the correlation of these flows. Pilot samples were retrieved …

Renormalization As A Tool For Nuclear Scattering & Binding, Chinmay Mishra

Doctoral Dissertations

Chiral effective field theory is the state-of-the-art when it comes to describing low-energy nuclear phenomena in a systematically-improvable and model-independent fashion. It is grounded in quantum chromodynamics – the fundamental theory underlying nuclear interactions – and consists of pion and nucleon degrees of freedom. In this framework, nuclear interaction is mediated by pions at long distances (in comparison to length scales at which quarks and gluons can be resolved), while finite-range “contact” terms account for the physics at short-distances. Together, they are organized into a hierarchy based on the orders (in powers of small momenta over a large momentum scale) …

Rapid Parameter Estimation Of Gravitational Wave Sources & Homologous Expansion In Common Envelope Events, Vinaya Valsan

Theses and Dissertations

Binary star systems are crucial for advancing our understanding of the universe. My doctoral research focuses on two related topics within the domain of binary star dynamics: gravitational waves from compact binary stars, and the evolution of the common envelope in stellar mass binaries.

In the era of multi-messenger astrophysics, swift identification and characterization of gravitational wave events is important for subsequent electromagnetic observations. The development of low-latency parameter estimation techniques is essential for providing astronomers with crucial information regarding the potential electromagnetic counterparts to gravitational wave signals. RapidPE is a highly parallelized parameter estimation scheme that achieves low-latency parameter …

Novel Physics In Unconventional Superconductors, Adil Amin

Theses and Dissertations

In this work, we consider the interplay of different magnetic orders and superconductivity.We consider both phenomenological and microscopic models to capture these interactions. The models are built using group theoretic arguments to ensure the constraints provided by the crystal symmetry are satisfied. We first consider a phenomenological theory for two transitions in superfluid 3He which involves coupling superfluidity and spin fluctuations through an approach called spin fluctuation feedback effect. We then apply this phenomenological approach to UPt3, PrOs4Sb12 and U1−xThxBe13 to obtain a common underlying mechanism for two superconducting transitions. We then consider odd-parity multipolar antiferromagnetic order i.e. Kramers’ degenerate …

Enhancing Interactions Among Dipole Excitations Using Surface Plasmon Polaritons: Quantum Entanglement And Classical Interactions, Jay Berres

Theses and Dissertations

The interaction of light with matter at the nano-scale continues to be an important research area for the application of nano-optical devices in wide ranging areas such as biosensing, light harnessing, and optical communications, to name a few. An important aspect of this is the interaction among dipole excitations (which includes classical dipole emitters, and dipole approximations of atoms, molecules, and other quantum objects), mediated by the device medium where they are located. Since the dimensions of these devices, by design, are at the nano-scale, the size of the dipole-dipole interaction space is much less than the wavelength of light …

Md Simulations Of Collision Effects For A Strongly Coupled Plasma, Jawon Jo

All Graduate Theses and Dissertations, Fall 2023 to Present

Studying strongly coupled plasmas can be effectively accomplished using molecular dynamics (MD) simulations. We have developed an advanced MD simulation code that can analyze plasmas with various coupling parameters. This code employs a spherically symmetric cut-off Coulomb force verified through convergence tests by modulating the cut-off and minimum force ranges. Additionally, it incorporates a new algorithm for optimizing the initial positions of particles at a given temperature. This method maintains the temperature constant and the velocity distribution unchanged. As a result, we eliminate the unphysical initial rises and oscillations in temperature that a random distribution of positions causes. The code …

Investigations Of Sulfurized Polymers For Their Use In Lithium-Sulfur Cells, Alan M. Rowland

All Theses

With the invention of the Lithium-Ion cell in the latter half of the 20th century, there has been a continued endeavor for innovation in compact energy-storage. Combined with the ever-growing need to move away from fossil fuels, electrochemical energy storage has seen a myriad of research projects in the pursuit of finding the ‘beyond-lithium’ cell. One of these projects that I personally assisted with was lithium-sulfur cells, which allow for a significantly greater energy storage capacity when compared to lithium-ion cells. In investigating a popular cathode in lithium-sulfur cells, sulfurized polyacrylonitrile (SPAN), it was hinted that there may be more …

Implementing General Moment Equations For Parallel Closures In Nimrod, Hankyu Lee

All Graduate Theses and Dissertations, Fall 2023 to Present

Understanding how magnetic fields impact plasma transport is essential for improving the efficiency of thermonuclear fusion power plants. To address the transport problem, both plasma fluid equations and Maxwell’s equations must be solved. To solve these equations, it is necessary to derive closure relations that allow the system to be closed. Previous closure models are useful for describing the behavior of high-collisionality plasma but are not effective at low collisionality. To obtain closure relations valid for low collisionality, the first-order drift kinetic equation must be solved.

This study presents methods for numerically obtaining parallel closures for NIMROD code by deriving …

Tuning Electronic Transport And Magnetic Properties Of Layered Magnetic Materials, Md Rafique Un Nabi

Graduate Theses and Dissertations

Two-dimensional magnetic materials (2DMMs) have gained significant interest due to their potential for novel physical phenomena and device applications. Mn2-xZnxSb, with its tunable magnetic properties and stable tetragonal layered structure, offers a rich platform for exploring these phenomena. The introduction of Zn into the Mn2Sb lattice efficiently tunes magnetic and electronic properties, making it a compelling candidate for high-performance spintronic devices. With this motivation, we synthesized Mn2-xZnxSb (0 ≤ x ≤ 1) single crystals using a flux method. Mn2Sb exhibits ferrimagnetic order below 550 K with antiparallel spins aligned along the c-axis for two Mn magnetic sublattice Mn(I) and Mn(II), …