Engineering Physics Commons^™

Radiosonde High Altitude Measurements Of Radiation Levels And Cosmic Ray Events, Ayodeji Opeyemi Akinuliola

Electronic Theses and Dissertations

Just above us, cosmic rays are hurtling in from space. These fast moving particles crash uncontrollably into molecules in the atmosphere, causing spontaneous decays of these particles. Despite the fact that we are broadly shielded from this radiation on earth, these particles can still disturb humans and electronics alike. Therefore, this research focuses on expanding the use of long-range radio transmitters such as radiosondes to transmit valuable data such as cosmic ray flux, geographical position, atmospheric temperature, pressure, etc. This can improve real-time radiation monitoring for aviation industry crew and passengers working in potentially higher radiation environments. On March 11, …

Structural Origin Of Thermal, Mechanical Properties And Morphological Behaviors Of Semiconducting Polymers, Song Zhang

Dissertations

The past decades have witnessed a surging exploration of semiconducting polymers for the application of wearable and flexible organic electronic devices. Despite the increased amounts of molecular engineered polymers and their much-improved electrical performances, a systematic study of the structure-thermal/mechanical property-morphology relationship of semiconducting polymers is still less investigated.

To understand the thin-film mechanical properties, a pseudo-free standing tensile tester was self-built and utilized to obtain their real-time stress-strain behaviors through uniaxial stretching on top of the water surface. It also enables the first quantitative measurement of fracture energy on ultrathin polymeric films. Through multiple mechanical testing methods (i.e., strain-rate …

Voltage-Controlled Magnetic Anisotropy In Antiferromagnetic Mgo-Capped Mnpt Films, P. H. Chang, Wuzhang Fang, T. Ozaki, Kirill Belashchenko

Kirill Belashchenko Publications

The magnetic anisotropy in MgO-capped MnPt films and its voltage control are studied using first-principles calculations. Sharp variation of the magnetic anisotropy with film thickness, especially in the Pt-terminated film, suggests that it may be widely tuned by adjusting the film thickness. In thick films the linear voltage control coefficient is as large as 1.5 and -0.6 pJ/Vm for Pt-terminated and Mn-terminated interfaces, respectively. The combination of a widely tunable magnetic anisotropy energy and a large voltage-control coefficient suggest that MgO-capped MnPt films can serve as a versatile platform for magnetic memory and antiferromagnonic applications.

Direct Drive Solar Panel Control Circuit, Marcorios Bekheit

Physics

A control circuit is built for insulated solar electric cookers (ISEC). Power delivery and temperature safety are the focus. Using a maximum power point tracking (MPPT) algorithm, Arduino Nano, voltage and current sensors, and a buck converter, the solar panel’s output power was maximized for a direct load heat resistor with 3.5Ω for a range of solar intensities. Using a resistance temperature detector, a temperature sensor is built for safety shutoff.

Designing Cryogenic Strain Device For 2d Materials, Jake Carter

Mechanical Engineering Undergraduate Honors Theses

The Churchill lab working within the Physics Department at the University of Arkansas is working to create important quantum states including weak topological insulators (TIs) through the use of symmetry engineering and topological electronic states in two-dimensional (2D) crystals of WHM materials. Experimental results of these topological states have been obstructed due to the difficulty to perform controlled in situ strain. This project strives to create a mount to utilize a piezoelectric nanopositioner within cryostats achieving an in situ strain that creates the quantum states the lab is looking to observe. This report also examines the necessary equations to determine …

Mechanical Behavior Of Cyclo-18 On Nickel And Copper Substrates, Reagan Michael Kraft

Mechanical Engineering Undergraduate Honors Theses

Carbyne, an -hybridized allotrope of carbon, has been the subject of many studies recently due to its incredible mechanical properties and small size. More recently, another -hybridized allotrope known as cyclo-18, has gained interest. In this study, computational molecular dynamics will be used to determine the mechanical properties of cyclo-18. Peeling and shearing tests of the molecule will be conducted on nickel and copper, which are respectively active and less-active transition metals. Additionally, a carbyne chain of equal length will undergo the same tests on the copper substrate to compare the mechanical properties of the two. The results conclude that …

Memory Module Design For High-Temperature Applications In Sic Cmos Technology, Affan Abbasi

Graduate Theses and Dissertations

The wide bandgap (WBG) characteristics of SiC play a significant and disruptive role in the power electronics industry. The same characteristics make this material a viable choice for high-temperature electronics systems. Leveraging the high-temperature capability of SiC is crucial to automotive, space exploration, aerospace, deep well drilling, and gas turbines. A significant issue with the high-temperature operation is the exponential increase in leakage current. The lower intrinsic carrier concentration of SiC (10-9 cm-3) compared to Si (1010 cm-3) leads to lower leakage over temperature. Several researchers have demonstrated analog and digital circuits designed in SiC. However, a memory module is …

Simulation Of Optical Properties Of Dielectric Layers From Visible To Near Infrared Spectral Range, Andrew Cochran, Cory Conkel

ONU Student Research Colloquium

Optical properties of dielectrics play a critical role in various applications including the design and manufacture of optical components & devices such as detectors, filters, imagers, lenses, optical coatings, photonic crystals, sensors and waveguides, and solar cells. Radiative properties of varying thicknesses of different dielectrics such as Aluminum Oxide (Al2O3), Silicon Dioxide (SiO2), Indium Tin Oxide (ITO), Magnesium Fluoride (MgF2) and Silicon Nitride (Si3N4) have been simulated and compared in the range of visible to near infrared by mathematical modelling using MATLAB simulations. The results of the evolution of the radiative properties, as a function of dielectric material thickness, on …

E. Coli And Total Coliform, Emilio Wilson

Undergraduate Research Competition

Water is important because we use it for our everyday use, whether it's for drinking, bathing, or for our enjoyment. Pollution causes the environment to have a harmful effect, which is usually caused by microorganisms (bacteria) Some of those Bacteria include E. coli and Total Coliform. They're mainly found in the intestines of humans, in animals, in water, and also found in the soil. Most of these bacteria are harmless but it can provide you with symptoms of diarrhea, vomiting, and stomach cramps. When water comes in contact with feces, humans, or any living organism, the water is contaminated. There …

Water Monitoring At Ccu (Conductivity, Ph, Do), Gage Campbell

Undergraduate Research Competition

Monitoring water quality is important for human health. This study focuses on the 544 West site and the parameters conductivity, pH, and dissolved oxygen (DO). Data used is from Oct. 2011 through Nov. 2020 on the Coastal Carolina University campus and used an Orion™ A329 multimeter. 741 samples were collected for Conductivity, with an average of 407.8 uS/cm (145.8 uS/cm - 690.7 uS/cm). 738 samples were collected for pH, with an average of 7.15 (6.09 - 8.11). All data fell within the SC DHEC water quality standard of pH which is no lower than 5.0 or above 8.5. 735 samples …

Detecting Radium-226 In Submarine Groundwater Discharge, Rashaun Davis

Undergraduate Research Competition

Studies have been done to see if abundance of neutrinos have an effect on the decay rate of radioactive nuclei. Questions regarding the proximity of the sun and the concentration of the flux of neutrinos as a result, have emerged due to there being more counts in the winter when the sun is closer versus there being less counts in the summer when the sun is farther away. Other studies say that the cause of the difference in counts are more local, as in the environmental conditions like temperature and various background radiation that interferes with the counts of the …

Design Of Smart Trashcan, Haoran Song

Senior Theses

A smart trashcan has been designed which can bring convenience to people for throwing their garbage away during the COVID-19 pandemic. A prototype is made from cardboard to demonstrate its function. This trashcan can sense people who are coming and leaving, and it can open and close automatically. The trashcan is powered by solar energy. A solar panel is mounted on top of the trashcan supporter. This design is specifically for use in China.

Deathtrap, Blake Traylor

Vázquez-Valarezo Poetry Award

I could have titled this one "Bad Trip in an Elevator," but that would twist the poem away from its authenticity. You'll have to trust me on this one: this happened. Not in the usual sense, but in that fiction-is-truth-in-a-funhouse-mirror, postmodern Tim O'Brien sense. And hallucinogens were not involved, nor are they encouraged or condoned. (Do with that Wretched Passive Voice what you will.)

If the word "Deathtrap" didn't amuse me so much, I really could have run with the title "Tired." Or maybe "Very Tired" would have been better. And then there are always the big-hitters: "Fatigue," "Exhaustion," "Are …

Investigation Of Trajectory And Control Designs For A Solar Sail To The Moon, Michelle Nadeau

Doctoral Dissertations and Master's Theses

NASA’s Artemis program and other government and commercial projects are working toward establishing a sustainable human presence on the moon. This thesis investigates the technical feasibility of a solar sail-based spacecraft (sailcraft) as a low-cost method of delivering cargo or science instruments to the moon and demonstrates how this sailcraft could be controlled to change its orbit. The concept is a low-cost, commercial launch vehicle-deployable, CubeSat-based sailcraft with a square sail, assumed attitude control, and a small payload traversing from low-Earth orbit toward the moon with zero propellant use. In this thesis, methods for sailcraft to increase altitude, the trajectory …

Zn Acceptors In Β-Ga2O3 Crystals, Timothy D. Gustafson, J. Jesenovec, Christopher A. Lenyk, Nancy C. Giles, J. S. Mccloy, M. Mccluskey, Larry E. Halliburton

Faculty Publications

Electron paramagnetic resonance (EPR) is used to identify and characterize neutral zinc acceptors in Zn-doped β-Ga₂O₃ crystals. Two EPR spectra are observed at low temperatures, one from Zn ions at tetrahedral Ga(1) sites (the Zn⁰_Ga1 acceptor) and one from Zn ions at octahedral Ga(2) sites (the Zn⁰_Ga2 acceptor). These Zn acceptors are small polarons, with the unpaired spin localized in each case on a threefold coordinated oxygen O(I) ion adjacent to the Zn ion. Resolved hyperfine interactions with neighboring ⁶⁹Ga and ⁷¹Ga nuclei allow the EPR spectra from the two acceptors …

Erratum: A Non-Linear Approximate Solution To The Damped Pendulum Derived Using The Method Of Successive Approximations [Georgia Journal Of Science, Vol. 76, No. 2, Article 9], Javier E. Hasbun

Georgia Journal of Science

In an earlier publication [Hill and Hasbun, 2018] considered an approximate solution to the damped pendulum, named the improved modified method of successive approximations (IMMSA), and compared it to an approximation from the work of [Johannessen, 2014]. Here, a correction is made to that comparison due to an error made in calculating Johannessen's approximation.

Correction To "Quantitative Study Of The Energy Changes In Voltage-Controlled Spin Crossover Molecular Thin Films" [The Journal Of Physical Chemistry Letters (2020) 11:19 (8231-8237) Doi: 10.1021/Acs.Jpclett.0c02209], Aaron Mosey, Ashley S. Dale, Guanhua Hao, Alpha N'Diaye, Peter Dowben, Ruihua Cheng

Peter Dowben Publications

In our recent publication, Figure 5 was published without adequate due diligence. The correct TOC Abstract graphic and Figure 5 are contained here in this correction. The correct on to off current ratios are in the range of 4 to 5, not 100 and the signal to noise ratios are far less than previously shown.

Nonvolatile Voltage Controlled Molecular Spin‐State Switching For Memory Applications, Thilini K. Ekanayaka, Guanhua Hao, Aaron Mosey, Ashley S. Dale, Xuanyuan Jiang, Andrew J. Yost, Keshab R. Sapkota, George T. Wang, Jian Zhang, Alpha T. N’Diaye, Andrew Marshall, Ruihua Cheng, Azad Naeemi, Xiaoshan Xu, Peter Dowben

Peter Dowben Publications

Nonvolatile, molecular multiferroic devices have now been demonstrated, but it is worth giving some consideration to the issue of whether such devices could be a competitive alternative for solid-state nonvolatile memory. For the Fe (II) spin crossover complex [Fe{H₂B(pz)₂}₂(bipy)], where pz = tris(pyrazol-1-yl)-borohydride and bipy = 2,20-bipyridine, voltage-controlled isothermal changes in the electronic structure and spin state have been demonstrated and are accompanied by changes in conductance. Higher conductance is seen with [Fe{H₂B(pz)₂}₂(bipy)] in the high spin state, while lower conductance occurs for the low spin state. Plausibly, …

Comparing Radiation Shielding Potential Of Liquid Propellants To Water For Application In Space, John Czaplewski

Master's Theses

The radiation environment in space is a threat that engineers and astronauts need to mitigate as exploration into the solar system expands. Passive shielding involves placing as much material between critical components and the radiation environment as possible. However, with mass and size budgets, it is important to select efficient materials to provide shielding. Currently, NASA and other space agencies plan on using water as a shield against radiation since it is already necessary for human missions. Water has been tested thoroughly and has been proven to be effective. Liquid propellants are needed for every mission and also share similar …

A Comparison Of Sporadic-E Occurrence Rates Using Ionosondes And Gps Radio Occultation Measurements, Rodney A. Carmona Jr.

Theses and Dissertations

Sporadic-E (Es) occurrence rates from Global Position Satellite radio occultation (GPS-RO) measurements have shown to vary by nearly an order of magnitude between studies, motivating a comparison with ground-based measurements. In an attempt to find an accurate GPS-RO technique for detecting Es formation, occurrence rates derived using five previously developed GPS-RO techniques are compared to ionosonde measurements over an eight-year period from 2010-2017. GPS-RO measurements within 170 km of a ionosonde site are used to calculate Es occurrence rates and compared to the ground-truth ionosonde measurements. Each technique is compared individually for each ionosonde site and then combined to determine …

Topological Realizations Of Entangling Quantum Gates, Adrian D. Scheppe

Theses and Dissertations

Topological systems are immune to decoherence and provide a hunting ground for qubits that are fault tolerant. The process of calculating linear operator representations of Majorana fermion exchanges or braids is well known and well documented; however, there is no documented intuition or algorithm which provides the opposite; braids from quantum gates. In this document, all possible linear representations of single, double, triple, and quadruple qubit gates are calculated to find several key patterns which provide crucial insight into the manifestation of qubit gates. A n x n gate will require n + 2 Majoranas with ½n + 1 trivial …

Nonlinear Solution Of The Time Eigenvalue Of A Fast Burst Reactor Using The Finite Volume Method, Stephen H. Baxter

Theses and Dissertations

This effort models fast burst reactors using the one dimensional, one group neutron diffusion equation to solve for the time eigenvalue, a method for which an analytical solution exists against which the numerical results can be verified. An existing solution method is enhanced by the addition of a second order accurate finite volume discretization, which is then used to model two separate fast burst reactors. The results of these models are then compared to the results of previous work, the analytical solution, and existing experimental burst width data for each of the two reactors.

Remote Mesoscopic Signatures Of Induced Magnetic Texture In Graphene, N. Arabchigavkani, R. Somphonsane, H. Ramamoorthy, G. He, J. Nathawat, S. Yin, B. Barut, K. He, M. D. Randle, R. Dixit, K. Sakanashi, N. Aoki, K. Zhang, L. Wang, W. N. Mei, Peter Dowben, J. Fransson, J. P. Bird

Peter Dowben Publications

Mesoscopic conductance fluctuations are a ubiquitous signature of phase-coherent transport in small conductors, exhibiting universal character independent of system details. In this Letter, however, we demonstrate a pronounced breakdown of this universality, due to the interplay of local and remote phenomena in transport. Our experiments are performed in a graphene-based interaction-detection geometry, in which an artificial magnetic texture is induced in the graphene layer by covering a portion of it with a micromagnet. When probing conduction at some distance from this region, the strong influence of remote factors is manifested through the appearance of giant conductance fluctuations, with amplitude much …

On-Chip Silicon Photonic Controllable 2 × 2 Four-Mode Waveguide Switch, Cao Dung Truong, Duy Nguyen Thi Hang, Hengky Chandrahalim, Minh Tuan Trinh

Faculty Publications

Multimode optical switch is a key component of mode division multiplexing in modern high-speed optical signal processing. In this paper, we introduce for the first time a novel 2 × 2 multimode switch design and demonstrate in the proof-of-concept. The device composes of four Y-multijunctions and 2 × 2 multimode interference coupler using silicon-on-insulator material with four controllable phase shifters. The shifters operate using thermo-optic effects utilizing Ti heaters enabling simultaneous switching of the optical signal between the output ports on four quasi-transverse electric modes with the electric power consumption is in order of 22.5 mW and the switching time …

Surface Acoustic Waves Increase Magnetic Domain Wall Velocity, Anil Adhikari, Shireen Adenwalla

Shireen Adenwalla Papers

Domain walls in magnetic thin films are being explored for memory applications and the speed at which they move has acquired increasing importance. Magnetic fields and currents have been shown to drive domain walls with speeds exceeding 500 m/s. We investigate another approach to increase domain wall velocities, using high frequency surface acoustic waves to create standing strain waves in a 3 micron wide strip of magnetic film with perpendicular anisotropy. Our measurements, at a resonant frequency of 248.8 MHz, indicate that domain wall velocities increase substantially, even at relatively low applied voltages. Our findings suggest that the strain wave …

Stellarator Optimization With Poloidal Field Coils, Haley Wilson, Andrew Ware, Aaron Bader, Chris Hegna

Undergraduate Theses, Professional Papers, and Capstone Artifacts

Stellarators are devices that use magnetic fields to optimize the conditions needed for plasmas to undergo fusion. Unlike tokamaks, stellarators do not rely on a plasma current but can produce a helical magnetic field using only external coils. In a stellarator, the coils surrounding the plasma are called modular coils and those that follow the plasma are called poloidal field coils. Modular coils can be difficult to build if they are too complex. An effort is underway to develop coil conditions that meet both physics and engineering constraints. The FOCUS code was developed to flexibly optimize stellarator coil configurations [C. …

Superresolution Enhancement With Active Convolved Illumination, Anindya Ghoshroy

Dissertations, Master's Theses and Master's Reports

The first two decades of the 21st century witnessed the emergence of “metamaterials”. The prospect of unrestricted control over light-matter interactions was a major contributing factor leading to the realization of new technologies and advancement of existing ones. While the field certainly does not lack innovative applications, widespread commercial deployment may still be several decades away. Fabrication of sophisticated 3d micro and nano structures, specially for telecommunications and optical frequencies will require a significant advancement of current technologies. More importantly, the effects of absorption and scattering losses will require a robust solution since this renders any conceivable application of metamaterials …

Proton Aurora At Mars: Assessing The Characteristics, Variability, And Driving Mechanisms Of A Newly Discovered Phenomenon, Andréa C.G. Hughes

Doctoral Dissertations and Master's Theses

The purpose of this doctoral research dissertation is to develop a deeper understanding of the phenomenology, variability and driving processes of proton aurora at Mars. Proton aurora are the most recently discovered of the three types of Martian aurora. Due to Mars’ lack of a global dipole magnetic field, the formation processes of Martian proton aurora are uniquely different than aurora on Earth. Martian proton aurora are expected to form on the planet’s dayside via electron stripping/charge exchange processes between solar wind protons and the neutral hydrogen corona. Herein, I present the results of a study of proton aurora at …

Multiscale Investigation Of Dropwise Condensation On A Smooth Hydrophilic Surface, Shahab Bayani Ahangar

Dissertations, Master's Theses and Master's Reports

The objective of this work is to identify the fundamental mechanism of dropwise condensation on a smooth solid surface by probing the solid-vapor interface during phase-change to evaluate the existence and structure of the thin film and the initial nucleus that develop during condensation. In this work, an automated Surface Plasmon Resonance imaging (SPRi) instrument with the ability to perform imaging in intensity modulation and angular modulation is developed. The SPRi instrument is used to probe (in three dimensions) the adsorbed film that forms on the substrate during dropwise condensation. SPRi with a lateral resolution of ~ 4-10 μm, thickness …

Development Of Synthetic Coal Char Simulant For Microwave Conversion Studies: A Computationally-Driven Approach, Kevin A. Hager

Graduate Theses, Dissertations, and Problem Reports (ETD)

Recent experimental demonstration of new reaction windows for coal char/methane reactions that are less energy-intensive, provides innovation for modular reactors. However, the correlation of the exact mechanism for the enhancement of these reaction windows is not certain. This study investigates the simplification of these experimental studies by developing a well-characterized coal char simulant. The approach involves using a computational approach to screen macroscopic composition to replicate the dielectric and compositional response of actual char. This study is focused on PRB coal char. A discrete element method (DEM) technique was used to simulate the packing of coal chars to give the …