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Beamed: A Bench For Automated Measurements Of Electrical Discharges - A New Standard For Paschen Curves, Jared Nelson

Doctoral Dissertations and Master's Theses

The initiation of electrical discharges, particularly glow discharges, plays a significant role in industry and environmental science, affecting systems such as electronics, power grids, and atmospheric phenomena. Despite extensive studies and applications of Paschen's law, current methodologies for experimental Paschen tests in direct current (DC) conditions lack standardized practices. This thesis presents the development and validation of a DC-based standard for electrical discharge initiation, using the BEnch for Automated Measurements of Electrical Discharges (BeAMED). BeAMED is designed to standardize the experimental process by automating electrical discharges' initiation and data acquisition. The autonomous nature of the system provides insights into the …

Electricity Generation From Air Movements For Microelectronics Applications, Rahul Nair, Kezang Choden

Australia-Bhutan Research Conference

This paper is about generating limited amount of electricity from natural air movements and air movements in a controlled environment . This is specifically applicable and useful in microelectronics application and as a pre charging . Air is composed of 71% Nitrogen and 21 % oxygen and rest of the gases comprising 8%. We understand that air also takes up from free radicals in the atmosphere due to various chemical reactions. The free radicals and ions have a random motion and movement in the air column. The controlled movement of air with charged particles which is essentially the free radicals …

A Fourth Planet In The Kepler-51 System Revealed By Transit Timing Variations, Kento Masuda, Jessica E. Libby-Roberts, John H. Livingston, Kevin B. Stevenson, Peter Gao, Shreyas Vissapragada, Guangwei Fu, Te Han, Michael Greklek-Mckeon, Suvrath Mahadevan, Eric Agol, Aaron Bello-Arufe, Zachory Berta-Thompson, Caleb I. Cañas, Yayaati Chachan, Leslie Hebb, Renyu Hu, Yui Kawashima, Heather A. Knutson, Caroline V. Morley, Catriona A. Murray

Pacific Faculty Work

Kepler-51 is a ≲1 Gyr old Sun-like star hosting three transiting planets with radii ≈6-9 R ⊕ and orbital periods ≈45-130 days. Transit timing variations (TTVs) measured with past Kepler and Hubble Space Telescope (HST) observations have been successfully modeled by considering gravitational interactions between the three transiting planets, yielding low masses and low mean densities (≲0.1 g cm⁻³) for all three planets. However, the transit time of the outermost transiting planet Kepler-51d recently measured by the James Webb Space Telescope 10 yr after the Kepler observations is significantly discrepant from the prediction made by the three-planet TTV …

Source Anisotropies And Pulsar Timing Arrays, Bruce Allen, Deepali Agarwal, Joseph D. Romano, Serena Valtolina

Physics & Astronomy Faculty Publications

Pulsar timing arrays (PTAs) hunt for gravitational waves (GWs) by searching for the correlations that GWs induce in the time-of-arrival residuals from different pulsars. If the GW sources are of astrophysical origin, then they are located at discrete points on the sky. However, PTA data are often modeled, and subsequently analyzed, via a “standard Gaussian ensemble.” That ensemble is obtained in the limit of an infinite density of vanishingly weak, Poisson-distributed sources. In this paper, we move away from that ensemble, to study the effects of two types of “source anisotropy.” The first (a), which is often called “shot noise,” …

(R2111) Effect Of Stenotic-Aneurysmal Arterial Regime On Unsteady Magnetohydrodynamic Non-Newtonian Blood Flow With Heat Radiation, Babatunde A. Joseph, Dada M. Sunday, Bello A.J. Funsho, Akeem B. Disu, Alamu-Awoniran F., Danas James Y.

Applications and Applied Mathematics: An International Journal (AAM)

The study aims to investigate the effect of magneto-hydrodynamic on a non-Newtonian unsteady blood flow with internal heat energy in the presence of blood ironic properties characterized by stenosis. The formulated mathematical equations resulted in differential forms and were solved analytically by Differential Transform Method. The obtained solutions were displayed by graphs showing different flow physiognomies like blood velocity, temperature profile, Nusselt number, wall shear stress and stream function.

The results indicated that velocity profile increases as magnetic field, Darcy number and aneurysmal artery rise, while it decreases as heat radiation, Reynold number, and Casson parameter speedup. The temperature profile …

Graphene-Based Antennas Utilizing Polyvinylidene Fluoride (Pvdf) Substrates For Attenuation, Josef Frankhouse

Mechanical Engineering Undergraduate Honors Theses

In this study, a Terahertz (THz) band antenna which can regulate its own resonant frequency without the requirement of manual adjustment is simulated. A polyvinylidene fluoride (PVDF) substrate is applied onto a rectangular graphene patch antenna. With a voltage potential applied onto the PVDF, the patch antenna can attenuate its frequency by physically changing the shape of the antenna, and in turn its resonant frequency. These antennas are within a 0.1 THz band between 1.32 THz to 1.22 THz measured from a radial bend of a flat surface to r = 75 , fitting into a return loss (S_{11 …}

Characterizing 2d Materials Using Positron Impact Induced Electron Spectroscopy And Development Of A Novel Thin Film Zno Based Piezo-Photonic Detector For Cryogenic And Mems Applications, Pratyanik Sau

2024 Fall Honors Capstone Projects - Archive

Surface analytical techniques are essential for engineering nano-detectors allowing characterization of their chemical composition, electromechanical properties, and physical structure. In the first chapter, the positron impact-induced secondary electron (PIISE) energy spectra and yield from single-layer graphene (SLG) and multi-layer graphene (MLG) grown on a polycrystalline Cu substrate have been presented. In the second chapter, an extensive catalog of Positron Induced Auger Spectra is presented to aid in the analysis of elemental composition of various materials. Additionally, in the third chapter, a novel detection scheme utilizing the piezo-pyroelectric properties of Zinc Oxide (ZnO) thin films have been demonstrated for its application …

Publisher Correction: Observation Of Dense Collisional Soliton Complexes In A Two-Component Bose-Einstein Condensate (Communications Physics, (2024), 7, 1, (163), 10.1038/S42005-024-01659-W), Sean M. Mossman, Garyfallia C. Katsimiga, Simeon I. Mistakidis, Alejandro Romero-Ros, Thomas M. Bersano, Peter Schmelcher, Panayotis G. Kevrekidis, Peter Engels

Physics Faculty Research & Creative Works

In the first paragraph of the Methods section, the sentence "We begin with an elongated BEC of approximately 9 x 10587Rb atoms…," has erroneously been written without a space between the two superscripts "5" and "87". This has now been corrected in both the HTML and PDF of the article, and the same expression reads: We begin with an elongated BEC of approximately 9 x 105 87Rb atoms…"

Wide-Angle Non-Uniform Optical Phased Array Using Compact And Efficient Antenna Design, Omar E. Elsheikh, Mohamed A. Swillam

Faculty Journal Articles

In the need for a more compact and efficient optical phased array with a wide steering beam for LIDAR applications, a wide steering array with high resolution is desirable. However, in the published work, a trade-off is often made for one over another. Apodized grating antennas have shown good efficiency with a compact size and wide beam profile, which improve optical phased array beam steering capability and are also compatible with the CMOS silicon photonics process. A promising studies shows enhancement in steering range with good resolution utilizing a non-uniform optical phased array. In this work, we present two highly …

Thermal Anharmonicity Of Transition Metals: A Case Study Of Tantalum, Bimal K C

Open Access Theses & Dissertations

Density functional theory (DFT) is commonly used for evaluating the thermal propertiesand equation of state of solids, usually within the quasi-harmonic approximation (QHA). In transition metals, thermodynamic quantities such as the thermal pressure and Gruneisen parameter are poorly reproduced compared with experimental values or with direct computational methods like quantum-molecular dynamics (QMD) simulations. Surprisingly, there has not been to date, a systematic study aimed at understanding the reasons for these discrepancies. Using Tantalum as a case study, we have evaluated the temperature dependence of the phonon frequencies employing Harmonic Ensemble Lattice Dynamics (HELD) combined with classical and quantum molecular dynamics. …

Design And Fabrication Of Graphene Solar Cells For Low-Power Energy Harvesting Systems, Tamzeed Bani Amin

Graduate Theses and Dissertations

This study presents the design and fabrication of graphene-based Schottky junction solar cells integrated into a 3-volt power system for low-power applications. Utilizing standard semiconductor processing methods, including selective oxide removal, metal contact deposition, and large-area graphene transfer, we fabricated solar cells from a silicon wafer coated with a thermal oxide layer. Each individual solar cell generated up to 270 µA of short-circuit current and an open-circuit voltage of 420 mV under illumination. We connected multiple solar cells in series to produce a total output of 3.3 volts, which is sufficient to recharge a 3-volt battery. The system, comprising these …

The Use Of Two-Dimensional Detectors For Snapshot And High Accuracy Imaging Ellipsometry, Jeremy A. Vanderslice

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Ellipsometry is a powerful and sensitive optical technique used to characterize thin film thickness and optical properties by measuring changes in the polarization state of light upon reflection or transmission. This dissertation investigates novel ellipsometry configurations that use two-dimensional detectors to enhance measurement speed, spatial resolution, or accuracy of ellipsometry measurements. The study involves the development of three different ellipsometry configurations, encompassing mechanical prototypes, mathematical models, and test measurements to evaluate each system.

Advisor: Jeffrey Shield

Density-Driven Investigations Of Ruthenium Binary Compounds Rux2 (X = O, S, N), Melanie White

UNLV Theses, Dissertations, Professional Papers, and Capstones

Exploration and fine-tuning of the energy landscape of materials can be accessed by means of changes in material density, a key principle of high pressure research. Density-driven changes impact variations in oxidation states and coordination numbers for the element constituents of a compound. Pressure-induced modification of intrinsic density can promote the formation of new materials, variations in physical properties, and transformations in crystallographic symmetry. With this as our foundation, we focus on ruthenium binary compounds - altering the anion species to change electronegativity while probing pressure and temperature effects. This led us to the present study of ruthenium oxide RuO2, …

Nodal Superconductivity In Miassite Rh17s15, Hyunsoo Kim, Makariy A. Tanatar, Marcin Kończykowski, Romain Grasset, Udhara S. Kaluarachchi, Serafim Teknowijoyo, Kyuil Cho, Aashish Sapkota, John M. Wilde, Matthew J. Krogstad, Sergey L. Bud'ko, Philip M.R. Brydon, Paul C. Canfield, Ruslan Prozorov

Physics Faculty Research & Creative Works

Solid state chemistry has produced a plethora of materials with properties not found in nature. For example, high-temperature superconductivity in cuprates is drastically different from the superconductivity of naturally occurring metals and alloys and is frequently referred to as unconventional. Unconventional superconductivity is also found in other synthetic compounds, such as iron-based and heavy-fermion superconductors. Here, we report compelling evidence of unconventional nodal superconductivity in synthetic samples of Rh₁₇S₁₅ (Tc = 5.4 K), which is also found in nature as the mineral miassite. We investigated the temperature-dependent variation of the London penetration depth Δλ(T) and the disorder …

A Near-Wall Methodology For Large-Eddy Simulation Based On Dynamic Hybrid Rans-Les, Michael Tullis, D. Keith Walters

Mechanical Engineering Faculty Publications and Presentations

Attempts to mitigate the computational cost of fully resolved large-eddy simulation (LES) in the near-wall region include both the hybrid Reynolds-averaged Navier–Stokes/LES (HRL) and wall-modeled LES (WMLES) approaches. This paper presents an LES wall treatment method that combines key attributes of the two, in which the boundary layer mesh is sized in the streamwise and spanwise directions comparable to WMLES, and the wall-normal mesh is comparable to a RANS simulation without wall functions. A mixing length model is used to prescribe an eddy viscosity in the near-wall region, with the mixing length scale limited based on local mesh size. The …

Clusteredlog: Optimizing Log Structures For Efficient Data Recovery And Integrity Management In Database Systems, Mariha Siddika Ahmad, Brajendra Panda

Electrical Engineering and Computer Science Faculty Publications and Presentations

In modern database systems, efficient log management is crucial for ensuring data integrity and facilitating swift recovery from potential data corruption or system failures. Traditional log structures, which store operations sequentially as they occur, often lead to significant delays in accessing and recovering specific data objects due to their scattered nature across the log. ClusteredLog addresses the limitations of traditional logging methods by implementing a novel logical organization of log entries. Instead of simply storing operations sequentially, it groups related operations for each data item into clusters. As a result, ClusteredLog enables faster identification and recovery of damaged data items …

Charge Transport In Two Dimensional Systems With Arbitrary Rashba And Dresselhaus Interactions, Abhishek Khanal

All Dissertations

In this thesis we discuss two different transport phenomena that occur in a two-dimensional electron system endowed with linear Rashba and Dresselhaus spin-orbit interactions of arbitrary values. First, in a semiclassical formalism we calculate the non-linear charge currents that appear in response to the simultaneous application of in-plane electric and magnetic fields. Working in a rotated system of coordinates that introduces $\alpha \pm \beta$ as effective couplings on perpendicular directions, we formulate a transport theory that relies on a second order distribution function derived in a local energy approximation and on chiral dependent relaxation times to show that the currents …

Fast Neutron & Gamma-Ray Scintillation And Broadband Photoluminescence From Gallium Nitride & Gallium Oxide: Developing Radiation-Hard Diagnostic Platforms, Daniel Jesus Valdes

UNLV Theses, Dissertations, Professional Papers, and Capstones

Integrated scintillation and electronics processing materials are of critical importance in environments exposed to high levels of radiation, such as nuclear fusion diagnostics and space missions. This dissertation focuses on the radiation detection capabilities of gallium oxide (Ga2O3) and gallium nitride (GaN), exploring their responses to fast neutrons and gamma rays. Using high-energy neutron beam facilities at Los Alamos Neutron Science Center (LANSCE) Flight Path 4FP60R, we exposed both Ga2O3 and GaN crystals to neutron irradiation spanning an energy spectrum ranging from 1 to 400 MeV. A Pi-Max 4 fast-gated Intensified CCD (ICCD) camera captured the transient scintillation responses for …

Theoretical Insights And Analysis Into Luneburg Lens, Aram Flores

Theses and Dissertations

Advancements in wireless communications necessitate innovative antenna designs for radar systems and satellite communications. The Luneburg lens, theorized by Rudolf Luneburg in 1944, is a gradient-index lens capable of focusing electromagnetic waves onto a point on its surface, offering potential improvements in antenna gain and performance. Access to the lenses, courtesy of Assured Space Access Incorporated, enabled me to research the lenses response, and specific design details remain confidential. Practical assessments of 3D-printed Luneburg lenses of varying sizes are limited, including factors such as lens alignment and focal point offset. This study investigates the performance of 6-inch and 13.25-inch Luneburg …

Computational Modeling In A Calculus-Based Physics Lab: Students’ Problems And Successes In Physics 2060, Abigail Sophia Flowers

Masters Theses

In the past few decades, computational modeling skills have become essential for students who want to pursue careers in physics or engineering. This issue of how to incorporate these skills into students' learning has become an important one because students in these degrees are already required to take several cognates outside of their chosen major. In 2018, Western Michigan University’s physics department decided to take on this issue by reformatting their introductory calculus-based physics labs to include computational modeling within the labs. The labs were first run in the Fall of 2018 and then were improved in spring 2019. When …

Single-Shot Mev-Resolution Hard X-Ray Spectrograph For Cavity-Based X-Ray Free Electron Laser, Keshab Kauchha

Dissertations

The Cavity-Based X-ray Free Electron Laser (CBXFEL) is a possible future direction in the development of fully coherent hard X-ray sources of high spectral brilliance, a narrow spectral bandwidth of ≃ 1 − 100 meV, and a high repetition rate of ≃ 1 MHz. A diagnostic tool is required to measure CBXFEL spectra with a meV resolution on a shot-to-shot basis.

The CBXFEL hard X-ray spectrograph is designed to image 9.831 keV X-rays in a ≃ 200 meV spectral window and with a spectral resolution of a few meV using an LCLS XFEL (Linac Coherent Light Source X-ray Free Electron …

Quantum Visual Feature Encoding Revisited, Xuan-Bac Nguyen, Hoang-Quan Nguyen, Hugh Churchill, Samee U. Khan, Khoa Luu

Computer Science and Computer Engineering Faculty Publications and Presentations

Although quantum machine learning has been introduced for a while, its applications in computer vision are still limited. This paper, therefore, revisits the quantum visual encoding strategies, the initial step in quantum machine learning. Investigating the root cause, we uncover that the existing quantum encoding design fails to ensure information preservation of the visual features after the encoding process, thus complicating the learning process of the quantum machine learning models. In particular, the problem, termed the “Quantum Information Gap” (QIG), leads to an information gap between classical and corresponding quantum features. We provide theoretical proof and practical examples with visualization …

Magnetic Nano And Micro Rods As Tools For Characterizing Materials Mechanical Properties: Fundamentals And Applications, Artis Brasovs

All Dissertations

The focus of this dissertation is insect blood (Hemolymph). Hemolymph is analyzed by taking a materials science approach. Rheological characterization of hemolymph has been performed for the first time. Owing to a minute amount of available material, a new protocol was established where Magnetic Rotational Spectroscopy (MRS) with ferromagnetic nanorods was employed. The challenge was examining the microliter droplets' viscosity in less than a few minutes. This challenge was successfully resolved.

Blood is critical for the insect's survival: after wounding, the insect has to seal the wound quickly, in a few minutes. As the mechanism of fast clotting has never …

Supporting Holistic, Informed, Decision-Making Through The Complementarity Of Life Cycle Assessment And Radiological Protection, Bryanna Wattier-Weisensee

All Dissertations

Decision making is challenging and it is necessary to consider all relevant data to make an informed decision. The work herein provides a pathway wherein the fields of radiological protection and life cycle assessment (LCA) can be utilized synergistically to benefit the decision-making using the other (and vice versa). Specifically, LCA parallels decision-aiding techniques used in the optimization of radiological protection and LCA includes an ionizing radiation potential (IRP) impact category wherein the impacts associated with an emission of radioactive material is quantified to determine the human health impact. Thus this body of work focuses on (1) expanding the platform …

Using The Schism Model And Hf Radar Data To Study Surface Currents In Texas Bays: A Case Study Of Sabine Lake (Sl) And Galveston Bay (Gb)., Cletus Ozoemena Ogbodo

Open Access Theses & Dissertations

Surface currents study provides invaluable understanding into the physical dynamics of oceans, bays, estuaries, and nearshore environments, offering critical insights about water movement and related coastal processes. These currents play a fundamental role in understanding the state of estuarine and marine systems, such as their effects on sediment transport, heat distribution and climate change, nutrient distribution, and pollutant dispersal. In addition, surface current data provides significant economic and ecological implications for coastal communities essential for managing resources effectively and ensuring the resilience of coastal regions against environmental and anthropogenic pressures. This study was driven by the need to address the …

Ohmic Contacts For Fabrication Of Sic Cmos Devices, Anthony Di Mauro

Graduate Theses and Dissertations

Today’s world of electronics is dominated by semiconductor devices which utilize silicon as their substrate material. Though, silicon is not ideal for semiconductor devices in high-voltage or high-temperature applications. Additionally, the efficiency of silicon devices becomes drastically reduced in nonideal operating conditions. Therefore, finding alternatives to silicon?based devices has been a topic for decades now. A few great candidates to replace silicon devices for said applications include Silicon Carbide (SiC), Gallium Nitride (GaN), and Aluminum Arsenide (AlAs). SiC has grown its reputation as the best candidate, when compared to other potential alternatives, due to its wide bandgap, high operating frequency, …

Cross-Interactions Of Amyloid Proteins: Implications For Aggregation Dynamics And Disease Pathology, Zhiyuan Song

All Dissertations

Amyloid aggregation is a pervasive form of protein misfolding implicated in the pathology of several prominent human diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), and type 2 diabetes (T2D). These diseases are marked by the accumulation of amyloid fibrils and toxic oligomers, which are highly dynamic and heterogeneous, posing challenges for understanding their roles in disease progression. Despite significant advances in the diagnosis and management of these conditions, no definitive cure is available. We investigate amyloid aggregation and cross-seeding, with a focus on amyloid-beta (Aβ), tau, alpha-synuclein (αS), and human islet amyloid polypeptide (IAPP) through discrete molecular dynamics (DMD) …

Multiphoton-Dressed Rydberg Excitations In A Microwave Cavity With Ultracold Rb Atoms, J. D.Massayuki Kondo, Seth T. Rittenhouse, Daniel Varela Magalhaes, Vasil Rokaj, S. I. Mistakidis, H. R. Sadeghpour, Luis Gustavo Marcassa

Physics Faculty Research & Creative Works

We investigate magneto-optical trap-loss spectroscopy of Rydberg excited Rb85 (66≤n≤68S1/2) atoms, placed inside a tailored microwave cavity. The cavity frequency at 13.053 GHz is in resonance with the 67S1/2→66P3/2 transition, inducing a ladder multiphoton microwave Rydberg absorption and emission. The observed spectra are modeled with an extended Jaynes-Cummings formalism that accounts for nonlinear multiphoton absorption from and emission into the cavity, the loss from the trap due to Rydberg excitation, and cavity imperfection. We calculate the average photons in each spectral feature and find evidence for fractional photon emission into the cavity modes within the loss spectra. The microwave cavity …

Observation Of Dense Collisional Soliton Complexes In A Two-Component Bose-Einstein Condensate, Sean M. Mossman, Garyfallia C. Katsimiga, Simeon I. Mistakidis, Alejandro Romero-Ros, Thomas M. Bersano, Peter Schmelcher, Panayotis G. Kevrekidis, Peter Engels

Physics Faculty Research & Creative Works

Solitons Are Nonlinear Solitary Waves Which Maintain their Shape over Time and through Collisions, Occurring in a Variety of Nonlinear Media from Plasmas to Optics. We Present an Experimental and Theoretical Study of Hydrodynamic Phenomena in a Two-Component Atomic Bose-Einstein Condensate Where a Soliton Array Emerges from the Imprinting of a Periodic Spin Pattern by a Microwave Pulse-Based Winding Technique. We Observe the Ensuing Dynamics Which Include Shape Deformations, the Emergence of Dark-Antidark Solitons, Apparent Spatial Frequency Tripling, and Decay and Revival of Contrast Related to Soliton Collisions. for the Densest Arrays, We Obtain Soliton Complexes Where Solitons Undergo Continued …

Dual Nature Of Magnetism Driven By Momentum Dependent F-D Kondo Hybridization, Byungkyun Kang, Yongbin Lee, Liqin Ke, Hyunsoo Kim, Myoung Hwan Kim, Chul Hong Park

Physics Faculty Research & Creative Works

The intricate nature of magnetism in uranium-based Kondo lattices is a consequence of correlations between U-5f and conduction electrons. Previously, the source of magnetism has been ascribed to either Mott physics or Ruderman-Kittel-Kasuya-Yosida interaction, both of which are not fully applicable to uranium-based Kondo lattices. Using linearized quasiparticle self-consistent GW plus dynamical mean-field theory, we demonstrate a crossover from incoherent to coherent f-d Kondo cloud in the paramagnetic phase of UTe₂, USbTe and USbSe. As the transition occurs, we observe an augmented f-d coherence and Pauli-like magnetic susceptibility, with a substantial frozen magnetic moment of U-5f persisting. We …