Digital Commons Network^™

Computational Fluid Dynamics Modeling Of Internal Wave Interactions On Conch Reef, Florida Keys, Megan Miller

All HCAS Student Capstones, Theses, and Dissertations

Internal waves breaking on continental shelves play a significant role in mixing and nutrient delivery to coral reef ecosystems. As internal solitary waves, or solitons, propagate shoreward onto continental slopes, they can become unstable and break into turbulent bores that bring cool, nutrient-rich sub-thermocline water shoreward onto coral reefs. The propagation of turbulent bores generated by internal waves interacting with a complex surface creates high-frequency variabilities in the thermal and nutrient environment of Conch Reef in the Florida Keys, which has been studied previously. Here, I have created a three-dimensional model using ANSYS Fluent Computational Fluid Dynamics (CFD) software to …

Jwst: Deuterated Pahs, Pah-Nitriles, And Pah 4 Overtone And Combination Bands I: Program Description And First Look, C. Boersma, L. J. Allamandola, Vincent J. Esposito, A. Maragkoudakis, J. D. Bregman, P. Temi, T. J. Lee, R. C. Fortenberry, E. Peeters

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

A first look is taken at the NIRSpec 1–5 μm observations from James Webb Space Telescope program 1591 that targets seven objects along the low-mass stellar life cycle with polycyclic aromatic hydrocarbon (PAH) emission. Spectra extracted from a 1'.'5 radius circular aperture are explored, showing a wealth of features, including the 3 μm PAH complex, the PAH continuum, and atomic and molecular emission lines from H i, He, H₂, and other species. CO₂- and H₂O-ice absorption and CO emission is also seen. Focusing on the bright-PDR position in M17, the PAH CH stretch falls …

Investigating The Effects Of A Southward Flow In The Southeastern Florida Shelf Using Robotic Instruments, Alfredo Quezada

All HCAS Student Capstones, Theses, and Dissertations

We deployed a Slocum G3 glider fitted with an acoustic Doppler current profiler (ADCP), a Conductivity-Temperature-Depth sensor (CTD), optics sensor channels, and a propeller on the Southeastern Florida shelf. The ADCP and CTD provide continuous measurements of Northern and Eastern current velocity components, salinity, temperature, and density, throughout the water column in a high-current environment. The optics sensor channels are able to provide measurements of chlorophyll concentrations, colored dissolved organic matter (CDOM), and backscatter particle counts. Additionally, for one of the glider deployments, we deployed a Wirewalker wave-powered profiling platform system also fitted with an ADCP and a CTD in …

Formulation Of Causality-Preserving Quantum Time Of Arrival Theory, Denny Lane B. Sombillo, Neris I. Sombillo

Physics Faculty Publications

We revisit the quantum correction to the classical time of arrival to address the unphysical instantaneous arrival in the limit of zero initial momentum. In this study, we show that the vanishing of arrival time is due to the contamination of the causality-violating component of the initial wave packet. Motivated by this observation, we propose to update the temporal collapse mechanism in Galapon (2009) [18] to incorporate the removal of causality-violating spectra of the arrival time operator. We found that the quantum correction to the classical arrival time is still observed. Thus, our analysis validates that the correction is an …

Renormalized Stress-Energy Tensor For Scalar Fields In Hartle-Hawking, Boulware, And Unruh States In The Reissner-Nordström Spacetime, Julio Arrechea, Cormac Breen, Adrian Ottewill, Peter Taylor

Articles

In this paper, we consider a quantum scalar field propagating on the Reissner-Nordström black hole spacetime. We compute the renormalized stress-energy tensor for the field in the Hartle-Hawking, Boulware and Unruh states. When the field is in the Hartle-Hawking state, we renormalize using the recently developed “extended coordinate” prescription. This method, which relies on Euclidean techniques, is very fast and accurate. Once, we have renormalized in the Hartle-Hawking state, we compute the stress-energy tensor in the Boulware and Unruh states by leveraging the fact that the difference between stress-energy tensors in different quantum states is already finite. We consider a …

Development Of Back-Scatter And Pile-Up Identification For Ucna+, Amelia Greathouse

Undergraduate Honors Theses

The UCNA Experiment at the Los Alamos Neutron Science Center (LANSCE) uses

an electron spectrometer to observe angular correlations between the neutron spin and the momenta of beta particles emitted during the process of beta (β) decay. Combined with neutron lifetime measurements, these observations probe physics beyond the standard model. In recent years there has been an effort to modernize the equipment to reduce the physical limitations of the experiment. The new prototype helps to reduce error via use of silicon photo-multipliers (SiPMs) and the SiPMs also have a greater quantum efficiency than the photomultiplier tubes (PMTs). However, there is …

The Ups And Downs Of Early Dark Energy Solutions To The Hubble Tension: A Review Of Models, Hints And Constraints Circa 2023, V. Poulin, Tristan L. Smith, T. Karwal

Physics & Astronomy Faculty Works

We review the current status of Early Dark Energy (EDE) models proposed to resolve the “Hubble tension”, the discrepancy between “direct” measurements of the current expansion rate of the Universe and “indirect measurements” for which the values inferred rely on the Λ CDM cosmological model calibrated on early-universe data. EDE refers to a new form of dark energy active at early times (typically a scalar-field), that quickly dilutes away at a redshift close to matter-radiation equality. The role of EDE is to decrease the sound horizon by briefly contributing to the Hubble rate in the pre-recombination era. We summarize the …

Depth-Resolved Defect Characterization Of Multi-Layer Thin-Film Semiconductor Materials Via Positron Annihilation Spectroscopy, Jack Driscoll

Physics Theses - Archive

Positron annihilation spectroscopy has frequently been used to perform depth-resolved defect characterization. In this thesis, the application of UTA's advanced positron beam to conduct depth-resolved defect studies on multi-layer semiconductor thin-film materials is demonstrated.

The Influence Of Subhaloes On Host Halo Properties, Lorena Mezini, Catherine E. Fielder, Andrew R. Zentner, Yao-Yuan Mao, Kuan Wang, Hao-Yi Wu

Physics Faculty Publications and Presentations

Within the ΛCDM cosmology, dark matter haloes are composed of both a smooth component and a population of smaller gravitationally bound subhaloes. These components are often treated as a single halo when properties, such as density profiles, are extracted from simulations. Recent work has shown that density profiles change substantially when subhalo mass is excluded. In this paper, we expand on this result by analysing three specific host halo properties – concentration (c_NFW), spin (λ_B), and shape (c/a) – when calculated only from the smooth component of the halo. This analysis …

Investigation Of The Chemical And Electronic Structure Of A 2h Phase Mos2 Single Crystal, Mary Blankenship

UNLV Theses, Dissertations, Professional Papers, and Capstones

Molybdenum disulfide has a wide range of applications in energy conversion devices, like thin-film solar cells, batteries, bio sensors, and more. Although the properties of MoS2 and other transition metal dichalcogenides (TMDC) have been widely studied, disagreements and discrepancies regarding its electronic structure remain.

In this thesis, a highly-oriented synthetic 2H phase MoS₂ single crystal is investigated using a toolchest of spectroscopic techniques to uncover its chemical and electronic properties. Lab-based x-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), inverse photoemission spectroscopy (IPES), and low energy electron diffraction (LEED) were performed at UNLV and combined with resonant inelastic soft …

Controlled Manipulation And Transport By Microswimmers In Stokes Flows, Jake Buzhardt

All Dissertations

Remotely actuated microscale swimming robots have the potential to revolutionize many aspects of biomedicine. However, for the longterm goals of this field of research to be achievable, it is necessary to develop modelling, simulation, and control strategies which effectively and efficiently account for not only the motion of individual swimmers, but also the complex interactions of such swimmers with their environment including other nearby swimmers, boundaries, other cargo and passive particles, and the fluid medium itself. The aim of this thesis is to study these problems in simulation from the perspective of controls and dynamical systems, with a particular focus …

Wavelet Compression As An Observational Operator In Data Assimilation Systems For Sea Surface Temperature, Bradley J. Sciacca

LSU New Orleans Theses and Dissertations

The ocean remains severely under-observed, in part due to its sheer size. Containing nearly billion of water with most of the subsurface being invisible because water is extremely difficult to penetrate using electromagnetic radiation, as is typically used by satellite measuring instruments. For this reason, most observations of the ocean have very low spatial-temporal coverage to get a broad capture of the ocean’s features. However, recent “dense but patchy” data have increased the availability of high-resolution – low spatial coverage observations. These novel data sets have motivated research into multi-scale data assimilation methods. Here, we demonstrate a new assimilation approach …

Measurement, Modeling, And Analysis Of The Energy Spectra Of Electrons And Annihilation Gammas Resulting From Low Energy Positron Irradiation Of Clean And Adsorbate Covered Surfaces, Sima Lotfimarangloo

Physics Dissertations - Archive

This dissertation presents measurements and theoretical modeling demonstrating the capability of Doppler Broadened annihilation gamma Spectroscopy (DBS) to provide element-specific information from the topmost atomic layer of surfaces that are either clean or covered with adsorbates or thin films. Our measurements show that the energy spectra of Doppler-shifted annihilation gamma photons emitted following the annihilation of positrons from the topmost atomic layers of clean gold (Au) and copper (Cu) differ significantly. With the aid of the positron annihilation-induced Auger electron spectroscopy (PAES) performed simultaneously with DBS, we show that measurable differences between the Doppler broadened gamma spectra from Au and …

Effect Of Self-Interaction Correction On Molecular Polarizabilities And Core Ionization Energies, Sharmin Akter

Open Access Theses & Dissertations

Density Functional Theory (DFT) is one of the most successful and popular computational Quantum Mechanical approaches to understanding materials. DFT allows the prediction of material properties from the electron density. Although in principle, density functional theory is exact, it, however, relies on approximate functional for exchange-correlation energy. Due to the approximate nature of the exchange-correlation functional, the self-Coulomb energy of the electrons is not exactly canceled out by the self-exchange, leading to the spurious self-interaction error (SIE). Due to this error, the potential shows incorrect behavior which leads to errors in calculated properties such as ionization energies, electron affinities, polarizabilities, …

The Study Of The Polarization Domains Of Mbe-Grown Barium Titanate Thin Films And Nanodots Using Pfm, Mohammad Zamani-Alavijeh

Graduate Theses and Dissertations

Polarization domains are the fundamental elements in ferroelectric materials that contribute to their properties. A natural polarization domain, which possesses a specific polarization direction or state, typically ranges in size from one unit cell to a few micrometers. Therefore, studying polarization domains requires the fabrication of materials and the measurement of ferroelectric properties at the nanoscale. In this study, molecular beam epitaxy (MBE) is employed to fabricate barium titanate (BTO) crystals, and piezoresponse force microscopy (PFM) is used to measure the properties of polarization domains at the nanoscale. In the beginning, this study identifies the reflection of high-energy electron diffraction …

Characterization Of Interlayer Laser Shock Peening During Fused Filament Fabrication Of Polylactic Acid (Pla), Fabien Denise

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The field of additive manufacturing (AM) has gained a significant amount of popularity due to the increasing need for more sustainable manufacturing techniques and the adaptive development of complex product geometries. The problem is that AM parts routinely exhibit flaws or weaknesses that affect functionality or performance. Over the years, surface treatments have been developed to compensate certain flaws or weaknesses in manufactured products. Combining surface treatments with the modularity of additive manufacturing could lead to more adaptable and creative improvements of product functions in the future. The current work evaluates the feasibility of pursuing a new research axis in …

Nuclear Charge Radius Determination Of Iridium Using Euv Spectroscopy Of Highly Charged Ions, Adam Hosier

All Dissertations

Highly charged ions have emerged on the scene of atomic physics because of their compressed electron cloud enhancing various physical phenomena. While transitions in ions and highly charged ions provide valuable information to different communities, their application in nuclear charge radius measurements becomes increasingly prominent. In this work, we report the extreme ultra-violet spectroscopy of Na-like ions and x-ray spectroscopy of Cu-like, Co-like, and Ni-like ions that explore nuclear charge distributions and the identification of new transitions, respectively.

In the first part of this work, extreme ultra-violet spectroscopy of highly charged ions of Na-like osmium and iridium was performed using …

An Optimized Search For Dark Matter In The Galactic Halo With Hawc, A. Albert, R. Alfaro, C. Alvarez, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A. Ayala Solares, E. Belmont-Moreno, K. S. Caballero-Mora, T. Capistrán, A. Carramiñana, S. Casanova, O. Chaparro-Amaro, U. Cotti, J. Cotzomi, E. De La Fuente, R. Diaz Hernandez, B. L. Dingus, M. A. Duvernois, M. Durocher, J. C. Diaz-Velez, C. Espinoza, M. M. Gonzalez, J. A. Goodman, J. P. Harding, D. Huang, F. Hueyotl-Zahuantitla, A. Iriarte, V. Joshi, G. J. Kunde, J. Lee, H. Leon Vargas, J. T. Linneman, A. L. Longinotti, G. Luis-Raya, J. Lundeen, K. Malone, O. Martinez, J. Martinez-Castro, J. A. Matthews, E. Moreno, M. Mostafa, A. Nayerhoda, L. Nellen, A. Peisker, E. G. Perez-Perez, C. D. Rho, D. Rosa-Gonzalez, H. Salazar, D. Salazar-Gallegos, A. Sandoval, J. Serna-Franco, R. W. Springer, O. Tibolla, K. Tollefson, I. Torres, R. Torres-Escobedo, R. Turner, F. Urena-Mena, L. Villasenor, Xiaojie Wang, H. Zhou, C. De Leon

Physics Faculty Research & Creative Works

The Galactic Halo is a key target for indirect dark matter detection. The High-Altitude Water Cherenkov (HAWC) observatory is a high-energy (∼300 GeV to >100 TeV) gamma-ray detector located in central Mexico. HAWC operates via the water Cherenkov technique and has both a wide field of view of ∼ 2 sr and a >95% duty cycle, making it ideal for analyses of highly extended sources. We made use of these properties of HAWC, and a new background-estimation technique optimized for extended sources to probe a large region of the Galactic Halo for dark matter signals. With this approach, we set …

Measuring The Lengths Of Sperm Whales Of The Northern Gulf Of Mexico By Wavelet Analysis Of Their Usual Clicks, George Drouant

LSU New Orleans Theses and Dissertations

Abstract

Acoustic recordings of underwater sounds produced by marine mammals present an attractive alternative to costly and logistically complex ship based visual surveys for collecting population data for various species.

The first reported use of underwater acoustic recordings in the long-term monitoring of sperm whale populations was by Ackleh et al. (Ackleh et al., 2012). The paper describes counting sperm whale clicks at different locations to track population changes over time.

Analysis of sperm whale clicks offers additional insight into sperm whale populations. The echo location clicks (usual clicks) of sperm whales can be used to give an estimate of …

Many-Body Quantum Chaos In Stroboscopically-Driven Cold Atoms, Ceren B. Dağ, Simeon I. Mistakidis, Amos Chan, H. R. Sadeghpour

Physics Faculty Research & Creative Works

In Quantum Chaotic Systems, The Spectral Form Factor (SFF), Defined As The Fourier Transform Of Two-Level Spectral Correlation Function, Is Known To Follow Random Matrix Theory (RMT), Namely A 'ramp' Followed By A 'plateau' In Late Times. Recently, A Generic Early-Time Deviation From RMT, So-Called The 'bump', Was Shown To Exist In Random Quantum Circuits As Toy Models For Many-Body Quantum Systems. We Demonstrate The Existence Of 'bump-Ramp-Plateau' Behavior In The SFF For A Number Of Paradigmatic And Stroboscopically-Driven 1D Cold-Atom Models: Spinless And Spin-1/2 Bose-Hubbard Models, And Nonintegrable Spin-1 Condensate With Contact Or Dipolar Interactions. We Find That The …

Lung Dosimetry Model Of Inhaled 222rn For Workers At Selected Building Material Factories In Erbil City, Iraq, Sardar Qader Othman, Ali Hassan Ahmed, Sarbaz Ibrahim Mohammed

Polytechnic Journal

Radon gas can cause lung harm, leading to extensive research on the biological effects of radon exposure in human lungs under various environmental conditions. The study estimates radon progeny doses for workers in Erbil city's building materials industries, focusing on alpha particle energy deposition, particle clearance, and lung deposition. Using a home condition of 1 Bq.m-3, radon progeny particle-absorbed doses in the trachea, bronchi, bronchioles, alveolar-interstitial sections, and lungs were determined in the first scenario. The 1 Bq.m-3 is replaced with the radon level for each factory to prepare its atmosphere in the second scenario. For the first scenario, the …

Capturing The Generation And Structural Transformations Of Molecular Ions, Jun Heo, Doeyeong Kim, Alekos Segalina, Hosung Ki, Doo-Sik Ahn, Seonggon Lee, Jungmin Kim, Yongjun Cha, Kyung Won Lee, Jie Yang, J. Pedro F. Nunes, Xijie Wang, Hyotcherl Ihee

Department of Physics and Astronomy: Faculty Publications

Molecular ions are ubiquitous and play pivotal roles^1–3 in many reactions, particularly in the context of atmospheric and interstellar chemistry^4–6. However, their structures and conformational transitions^7,8, particularly in the gas phase, are less explored than those of neutral molecules owing to experimental difficulties. A case in point is the halonium ions^9–11, whose highly reactive nature and ring strain make them short-lived intermediates that are readily attacked even by weak nucleophiles and thus challenging to isolate or capture before they undergo further reaction. Here we show that megaelectronvolt ultrafast electron diffraction (MeV-UED)^12–14, …

Dynamics And Scaling Of Particle Streaks In High-Reynolds-Number Turbulent Boundary Layers, Tim Berk, Filippo Coletti

Mechanical and Aerospace Engineering Faculty Publications

Inertial particles in wall-bounded turbulence are known to form streaks, but experimental evidence and predictive understanding of this phenomenon is lacking, especially in regimes relevant to atmospheric flows. We carry out wind tunnel measurements to investigate this process, characterizing the transport of microscopic particles suspended in turbulent boundary layers. The friction Reynolds number Re_𝜏 = O(10⁴) allows for significant scale separation and the emergence of large-scale motions, while the range of viscous Stokes number St⁺ = 18–870 is relevant to the transport of dust and fine sand in the atmospheric surface layer. We …

Analytic Distribution Of The Optimal Cross-Correlation Statistic For Stochastic Gravitational-Wave-Background Searches Using Pulsar Timing Arrays, ‪Jeffrey S. Hazboun, Patrick M. Meyers, Joseph D. Romano, Xavier Siemens, Anne M. Archibald

Physics & Astronomy Faculty Publications

We show via both analytical calculation and numerical simulation that the optimal cross-correlation statistic (OS) for stochastic gravitational-wave-background (GWB) searches using data from pulsar timing arrays follows a generalized chi-squared (GX2) distribution—i.e., a linear combination of chi-squared distributions with coefficients given by the eigenvalues of the quadratic form defining the statistic. This observation is particularly important for calculating the frequentist statistical significance of a possible GWB detection, which depends on the exact form of the distribution of the OS signal-to-noise ratio ρˆ ≡ Aˆ 2 gw=σ0 in the absence of GW-induced cross correlations (i.e., the null distribution). Previous discussions of …

Search For Evidence Of Baryogenesis And Dark Matter In B+→Ψd+P Decays At Babar, J. P. Lees, V. Poireau, E. Grauges, A. Palano, G. Eigen, D. N. Brown, Yu. G. Kolomensky, M. Fritsch, H. Koch, R. Cheaib, C. Hearty, T. S. Mattison, J. A. Mckenna, R. Y. So, V. E. Blinov, A. R. Buzykaev, V. P. Druzhinin, E. A. Kravchenko, Milind Purohit, Et. Al.

Faculty Publications

A new dark sector antibaryon, denoted ψD, could be produced in decays of B mesons. This Letter presents a search for B⁺→ψ_D+p (and the charge conjugate) decays in e⁺e⁻ annihilations at 10.58 GeV, using data collected in the BABAR experiment. Data corresponding to an integrated luminosity of 398 fb⁻¹ are analyzed. No evidence for a signal is observed. Branching fraction upper limits in the range from 10⁻⁷–10⁻⁵ are obtained at 90% confidence level for masses of 1.0<mψ_D< 4.3 GeV/c². The result is also reinterpreted to provide …

Assessing The Robustness Of Sound Horizon-Free Determinations Of The Hubble Constant, Tristan L. Smith, V. Poulin, T. Simon

Physics & Astronomy Faculty Works

The Hubble tension can be addressed by modifying the sound horizon (r_s) before recombination, triggering interest in early universe estimates of the Hubble constant, H₀, independent of r_s. Constraints on H₀ from an r_s-free analysis of the full shape BOSS galaxy power spectra within Λ CDM were recently reported and used to comment on the viability of physics beyond Λ CDM. Here we demonstrate that r_s-free analyses with current data depend on both the model and the priors placed on the cosmological parameters, such that Λ CDM analyses …

Detailed Characterization Of A Khz-Rate Laser-Driven Fusion At A Thin Liquid Sheet With A Neutron Detection Suite, Benjamin M. Knight, Connor M. Gautam, Colton R. Stoner, Bryan V. Egner, Joseph R. Smith, Christopher M. Orban, Juan J. Manfredi, Kyle Frische, Michael L. Dexter, Enam A. Chowdury, Anil K. Patnaik

Faculty Publications

We present detailed characterization of laser driven fusion and neutron production (∼10⁵/second) employing 8 mJ, 40fs laser pulses on a thin (< 1 µm) D₂O liquid sheet employing a measurement suite. At relativistic intensity (∼5×10¹⁸W/cm²) and high repetition-rate (1 kHz), the system produces consistent D-D fusion, allowing for consistent neutron generation. Evidence of D-D fusion neutron production is verified b y a measurement suite with three independent detection systems: an EJ-309 organic scintillator with pulse-shape discrimination, a ³He proportional counter, and a set of 36 bubble detectors. Time-of-flight analysis of the scintillator data shows …

Perovskite Cspbbr3 Solar Cells With Novel Hole-Transporting Layer Of Metal Complexes, Liqiu Zheng, Evynn S. Jackson, Ny'kesha S. Warren, Robert Owor, Zhongrui Li

Georgia Journal of Science

For the first time, the novel application of Schiff-base copper complexes in all-inorganic perovskite CsBrBr₃ solar cells has been explored and turns out they could be utilized as effective hole-transporting materials. Schiff-base copper complexes with halogen ligands (R=Cl and Br) are synthesized with an ease approach at a low cost, both of which exhibit decent power conversion efficiency of 4.55% and 5.71%, respectively, when being constructed into solar devices as hole transport layers. Thanks to high thermal/chemical stability of those Schiff-base metal complexes, the strengthened stability was achieved which is comparable to that of carbon-based CsBrBr₃ solar cells. …

Coastal Bathymetry Of Uae Using Satellite-Based Remote Sensing Data, Naser Salem Aldahmani

Thesis/ Dissertation Defenses

The thesis focuses on studying coastal bathymetry in the United Arab Emirates using satellite images. Developing a coastal bathymetry map in the coastal areas of the United Arab Emirates using optical satellite data and analyzing quality and accuracy. Multiple algorithms are used to draw these maps, and the project involves using the linear scale ratio to derive bathymetry in areas such as Fujairah Port and Dalma Island using Sentinel-2 images. Multiple tools in the SNAP application platform were used to perform these operations, including atmospheric correction, resampling, ground masking, sunshine removal, and dark object subtraction. Finally, the Sen2coral plugin was …

Measurement Of Additional Radiation In The Initial-State-Radiation Processes E+E- →Μ+Μ- Y And E+E- → ℼ+ℼ- Y At Babar, J. P. Lees, V. Poireau, V. Tisserand, E. Grauges, A. Palano, G. Eigen, D. N. Brown, Yu. G. Kolomensky, M. Fritsch, H. Koch, R. Cheaib, C. Hearty, T. S. Mattison, J. A. Mckenna, R. Y. So, V. E. Blinov, A. R. Buzykaev, V. P. Druzhinin, E. A. Kozyrev, Milind Purohit, Et. Al.

Faculty Publications

A dedicated measurement of additional radiation in e⁺e⁻ → µ⁺µ⁻γ and e⁺e⁻ → π⁺π⁻γ initial-state-radiation events is presented using the full BABAR data sample. For the first time results are presented at next-to- and next-to-next-to-leading order, with one and two additional photons, respectively, for radiation from the initial and final states. Comparison with predictions from PHOKHARA and AFKQED Monte Carlo generators is performed, revealing discrepancies in the one-photon rates and angular distributions for the former. This disagreement has a negligible effect on the BABAR measurement of …