Master of Science (M.S.), University of Dayton, 2024, Materials Engineering

If gone undetected, volcanic ash in the atmosphere can have significant negative effects on the performance of air-breathing gas turbine engines. When ingested into the front of the engine, abrasion and erosion of key mechanical components can occur, accompanied by degradation of the materials located in the late-stages of the engine by ash that has become molten due to the high-temperature environment. These phenomena can lead to significant damage and premature failure in a fielded gas-turbine engine, thus the need to evaluate engine materials prior to their implementation arises. While volcanic ashes and turbine engine materials have been studied extensively in the literature, they have largely been studied independently, therefore no standardized volcanic ash media to be used in materials testing has been developed. In this work, a group of natural volcanic ash samples were evaluated using a variety of techniques to understand their chemical, physical, and thermal behavior. The information gathered in the characterization of the group of natural ash samples was then used to develop a synthetic volcanic ash media that has similar chemistry to and behaves like a natural ash when exposed to an environment like that in a late-stage gas turbine engine. The new synthetic ash media was compared to a natural ash, from Mt. Mazama in Oregon, USA. Specifically, its ability to melt and infiltrate the microstructural features of 7% yttria-stabilized zirconia thermal barrier coatings deposited on superalloy coupons was examined. It was shown via SEM analysis that when heated to 1200 °C, the synthetic ash melts and infiltrates the thermal barrier coating within a comparable time (<30 minutes) as Mt. Mazama ash, leading to the conclusion that it can be deemed an effective replacement for natural volcanic ash in materials testing. The development of this synthetic ash test media is meant to provide a solid starting point for future development of medias used (open full item for complete abstract)

Committee: Li Cao Ph.D. (Committee Chair); Matthew Hartshorne Ph.D. (Advisor); Donald Klosterman Ph.D. (Committee Member) Subjects: Aerospace Materials; Chemistry; Earth; Engineering; Geology; High Temperature Physics; Materials Science; Mineralogy

Master of Science (M.S.), University of Dayton, 2024, Aerospace Engineering

This research introduces an Origami-inspired dynamic spacecraft radiator, capable of adjusting heat rejection in response to orbital variations and extreme temperature fluctuations in lunar environments. The research centers around the square twist origami tessellation, an adaptable geometric structure with significant potential for revolutionizing radiative heat control in space. The investigative involves simulations of square twist origami tessellation panels using vector math and algebra. This study examines both a two-dimensional (2- D), infinitely thin tessellation, and a three-dimensional (3-D), rigidly-foldable tessellation, each characterized by an adjustable closure or actuation angle “φ”. Meticulously analyzed the heat loss characteristics of both the 2D and 3D radiators over a 180-degree range of actuation. Utilizing Monte Carlo Ray Tracing and the concept of “view factors”, the study quantifies radiative heat loss, exploring the interplay of emitted, interrupted, and escaped rays as the geometry adapts to various positions. This method allowed for an in-depth understanding of the changing radiative heat loss behavior as the tessellation actuates from fully closed to fully deployed. The findings reveal a significant divergence between the 2D and 3D square twist origami radiators. With an emissivity of 1, the 3D model demonstrated a slower decrease in the ratio of escaped to emitted rays (Ψ) as the closure/actuation angle increased, while the 2D model exhibited a more linear decline. This divergence underscores the superior radiative heat loss control capabilities of the 2D square twist origami geometry, offering a promising turndown ratio of 4.42, validating the model's efficiency and practicality for radiative heat loss control. Further exploration involved both non-rigidly and rigidly foldable radiator models. The non-rigidly foldable geometry, initially a theoretical concept, is realized through 3D modeling and physica (open full item for complete abstract)

Committee: Rydge Mulford (Advisor) Subjects: Acoustics; Aerospace Engineering; Aerospace Materials; Alternative Energy; Aquatic Sciences; Artificial Intelligence; Astronomy; Astrophysics; Atmosphere; Atmospheric Sciences; Automotive Engineering; Automotive Materials; Biomechanics; Biophysics; Cinematography; Civil Engineering; Communication; Computer Engineering; Design; Earth; Educational Software; Educational Technology; Educational Tests and Measurements; Educational Theory; Electrical Engineering; Engineering; Environmental Engineering; Environmental Science; Experiments; Fluid Dynamics; Geophysics; Geotechnology; High Temperature Physics; Industrial Engineering; Information Systems; Information Technology; Instructional Design; Marine Geology; Materials Science; Mathematics; Mathematics Education; Mechanical Engineering; Mechanics; Mineralogy; Mining Engineering; Naval Engineering; Nuclear Engineering; Nuclear Physics; Ocean Engineering; Petroleum Engineering; Quantum Physics; Radiation; Radiology; Range Management; Remote Sensing; Robotics; Solid State Physics; Sustainability; Systems Design; Theoretical Physics

Master of Science, University of Akron, 2023, Geology

Within the mid to lower continental crust distributed ductile thinning occurs, in orogens that form mountains like the Himalayas and Appalachia, due to a weak middle to lower crust that deforms laterally in response to loading of a thickened, cold upper crust. This thinning destabilizes large orogens and causes the exhumation of hot and weak rock from the mid to lower crust that begins to partially melt. This melting further weakens the rocks and may affect the deformation mechanisms operating in the crust. Melting has been seen to have impacts on the deformation mechanisms and resulting lattice preferred orientations (LPO) that form in olivine-basalt aggregates (Holtzman et al., 2003). To investigate the effects of partial melting on deformation mechanisms and LPO development in two common foliated felsic rocks, I performed general shear deformation experiments on a fine-grained quartzite and fine-grained gneiss at T = 800°C, 850°C, 900°C, 950°C, or 975°C, P = 1.5 GPa, and strain rate of 6*10-5/s. The quartzite (grain size ~30 microns) is composed of 90% quartz and 10% muscovite. The fine-grained gneiss (grain size ~50 microns) is composed of 43% quartz, 40% plagioclase, 16% biotite, and 1% accessory minerals. The foliation in the slices of each rock was oriented parallel to the shear plane between Al2O3 shear pistons with a cut made at 45° to the compression direction. Experiments were performed at a range of temperatures to change the melt fraction present in the rocks during deformation (Melt = ~0%, 0.25%, 0.5%, and 1%). The yield stress of Moine Thrust quartzite decreased as a function of increasing temperature from ~1000 to ~300 MPa. However, all the experiments with melt present (T equal to to greater than 850°C) significantly strain hardened after a shear strain (g) of 1. This hardening may be due to the presence of melt along grain boundaries which is absorbing water from the recrystallizing quartz grains which slows diffusive recovery in quartz. The Gne (open full item for complete abstract)

Committee: Caleb Holyoke (Advisor); John Peck (Committee Member); Molly Witter-Shelleman (Committee Member) Subjects: Earth; Environmental Geology; Experiments; Geochemistry; Geological; Geology; Geophysics; Geotechnology; High Temperature Physics; Mineralogy; Petrology

PHD, Kent State University, 2022, College of Arts and Sciences / Department of Physics

Compact stars (CSs) are the remnants of “dead” stars that were too small to form black holes; the category includes both white dwarfs (WDs) and neutron stars (NSs). To produce a full description of any magnetized compact star requires solving Einstein's equations in unison with Maxwell's equations. However, when putting these two sets of equations together, there is an additional degree of freedom that requires the inclusion of the equation of state (EOS) of the stellar matter in question. The most notable difference between CSs and other stars is that CSs consist of degenerate fermion matter. Fermionic matter exists in a degenerate state when the temperature is low compared to the Fermi energy. Such states arise due to the Pauli exclusion principle, which states that no two identical fermions (particles with half integer spin) in the same quantum system may inhabit the same quantum state. In the case of WDs, this degeneracy is caused solely by electrons; whereas, in NSs, the degeneracy is in several species of particles including neutrons and protons, but also more “exotic” baryons, such as Lambdas, Sigmas, and Cascades. In the grand canonical ensemble, the stellar EOS is typically expressed as the relation between the total energy density of a gas of particles and their pressure. It is calculated using thermodynamics with, in the NS case, an additional contribution from the strong nuclear force, which must be modeled. Due to computational difficulty, the EOS is often calculated in a simplified way, assuming that one aspect or another is not significant. As such, EOSs exist with temperature effects or with magnetic field effects, but not with both. For example, higher temperatures (without additional degrees of freedom) lead to higher pressures at the same energy density; the EOS is “stiffer.” Magnetic fields lead to a pressure anisotropy and Landau quantization, which gives rise to De Haas-Van Alphen oscillations in the EOS. This thesis breaks new ground by sim (open full item for complete abstract)

Committee: Veronica Dexheimer (Advisor); Michael Strickland (Committee Member); Gokarna Sharma (Committee Member); Lothar Reichel (Committee Member); Khandker Quader (Committee Member) Subjects: Astrophysics; Electromagnetism; High Temperature Physics; Particle Physics; Physics; Plasma Physics; Quantum Physics; Theoretical Physics

Doctor of Philosophy, The Ohio State University, 2022, Physics

The success of modern digital electronics relies on compartmentalizing logical functions into individual gates, and controlling their order of operations via a global clock. In the absence of such a timekeeping mechanism, systems of connected logic gates can quickly become chaotic and unpredictable -- exhibiting analog, asynchronous, autonomous dynamics. Such recurrent circuitry behaves in a manner more consistent with neural networks than digital computers, exchanging and conducting electricity as quickly as its hardware allows. These physics enable new forms of information processing that are faster and more complex than clocked digital circuitry. However, modern electronic design tools often fail to measure or predict the properties of large recurrent networks, and their presence can disrupt other clocked architectures. In this thesis, I study and apply the physics of complex networks of self-interacting logic gates at sub-ns timescales. At a high level, my unique contributions are: 1. I derive a general theory of network dynamics and develop open-source simulation libraries and experimental circuit designs to re-create this work; 2. I invent a best-in-class digital measurement system to experimentally analyze signals at the trillionth-of-a-second (ps) timescale; 3. I introduce a network computing architecture based on chaotic fractal dynamics, creating the first `physically unclonable function' with near-infinite entropy. In practice, I use a digital computer to reconfigure a tabletop electronic device containing millions of logic gates (a field-programmable gate array; FPGA) into a network of Boolean functions (a hybrid Boolean network; HBN). From within the FPGA, I release the HBN from initial conditions and measure the resulting state of the network over time. These data are transferred to an external computer and used to study the system experimentally and via a mathematical model. Existing mathematical theories and FPGA simulation tools produce in (open full item for complete abstract)

Committee: Daniel Gauthier (Advisor); Emre Koksal (Committee Member); Gregory Lafyatis (Committee Member); Antonio Boveia (Committee Member) Subjects: Applied Mathematics; Computer Engineering; Computer Science; Condensed Matter Physics; Electrical Engineering; Electromagnetics; Electromagnetism; Engineering; Experiments; High Temperature Physics; Information Science; Information Systems; Information Technology; Low Temperature Physics; Materials Science; Mathematics; Medical Imaging; Nanotechnology; Particle Physics; Physics; Quantum Physics; Scientific Imaging; Solid State Physics; Systems Design; Technology; Theoretical Physics

Doctor of Philosophy (PhD), Ohio University, 2020, Physics and Astronomy (Arts and Sciences)

Understanding thermionic cathodes is crucial for the future development of communication technologies operating at the terahertz frequency. Model cathode systems were characterized using multiple experimental techniques. These included Low Energy Electron Microscopy, X-Ray Photoemission Spectroscopy, and Auger Electron Spectroscopy. This was done to determine the mechanisms by which tungsten, barium, scandium, and oxygen may combine in order to achieve high current densities via thermionic emission. Barium and scandium films are found to dewet from the tungsten surfaces studied, and not diffuse out from bulk sources. The dewetted droplets were found to contribute the most to thermal emission. Barium oxide and scandium oxide are also found to react desorb from the emitting surface at lower temperatures then the metals themselves. The function of scandium in scandate cathodes was determined to act as an inhibitor to oxide formation. These observations are not compatible with certain models of cathode operation, mainly the dipole and semi-conductor models.

Committee: Martin Kordesch (Advisor) Subjects: Condensed Matter Physics; Experiments; High Temperature Physics; Materials Science; Physics

Doctor of Engineering, Cleveland State University, 2017, Washkewicz College of Engineering

This dissertation explores the role of different types of convection on macrosegregation and on dendritic array morphology of two aluminum alloys directionally solidified through cylindrical graphite molds having both cross-section decrease and increase. Al- 19 wt. % Cu and Al-7 wt. % Si alloys were directionally solidified at two growth speed of 10 and 29.1 µm s-1 and examined for longitudinal and radial macrosegregation, and for primary dendrite spacing and dendrite trunk diameter. Directional solidification of these alloys through constant cross-section showed clustering of primary dendrites and parabolic-shaped radial macrosegregation profile, indicative of “steepling convection” in the mushy-zone. The degree of radial macrosegregation increased with decreased growth speed. The Al- 19 wt. % Cu samples, grown under similar conditions as Al-7 wt. % Si, showed more radial macrosegregation because of more intense “stepling convection” caused by their one order of magnitude larger coefficient of solutal expansion. Positive macrosegregation right before, followed by negative macrosegregation right after an abrupt cross-section decrease (from 9.5 mm diameter to 3.2 mm diameter), were observed in both alloys; this is because of the combined effect of thermosolutal convection and area-change-driven shrinkage flow in the contraction region. The degree of macrosegregation was found to be higher in the Al- 19 wt. % Cu samples. Strong area-change-driven shrinkage flow changes the parabolic-shape radial macrosegregation in the larger diameter section before contraction to “S-shaped” profile. But in the smaller diameter section after the contraction very low degree of radial macrosegregation was found. The samples solidified through an abrupt cross-section increase (from 3.2 mm diameter to 9.5 mm diameter) showed negative macrosegregation right after the cross-section increase on the expansion platform. During the transition to steady-state after the expansion, radia (open full item for complete abstract)

Committee: Surendra Tewari Ph.D. (Advisor); Jorge Gatica Ph.D. (Committee Member); Orhan Talu Ph.D. (Committee Member); Rolf Lustig Ph.D. (Committee Member); Kiril Streletzky Ph.D. (Committee Member) Subjects: Aerospace Materials; Automotive Materials; Chemical Engineering; Condensed Matter Physics; Engineering; Fluid Dynamics; High Temperature Physics; Materials Science; Metallurgy

PHD, Kent State University, 2017, College of Arts and Sciences / Department of Physics

This research work is in the field of experimental nuclear physics, more specifically, the analysis of data taken with the Solenoidal Tracker at RHIC (STAR) apparatus at the Relativistic Heavy Ion Collider (RHIC) located at Brookhaven National Laboratory (BNL). There, we accelerate and collide beams of heavy ions (e.g. gold nuclei) at relativistic velocities. The collisions of heavy nuclei in the STAR Experiment compress nuclear matter to high densities, and heat it to extreme temperatures, over one trillion degrees Celsius. Under such conditions, Lattice QCD and other phenomeno- logical models predict a phase transition in nuclear matter, a transition, where quarks and gluons become deconfined, i.e. they freely move throughout the interaction volume and are no longer confined to individual nucleons, forming Quark Gluon Plasma (QGP), a new state of nuclear matter. The study of QGP, its properties and dynamics, will provide a better understanding of QCD, the strong force, and of the history of the early universe. Mesons containing heavy flavor (charm and bottom) quarks can be used in QGP searches. Heavy quarks are produced mainly in the early stages of a collisions via energetic parton-parton interactions; heavy flavor production in QGP or during hadronization is suppressed due to the high masses of the quarks. Heavy quarks can therefore be used to probe the whole evolution of the system and as a calibrated tool to better understand the nature of the early, hot matter formed in the collisions. A key finding by the experiments at RHIC is the anomalously low production of heavy flavor at high transverse momentum values. This was found by measuring the yields of the decay electrons from mesons containing either charm or bottom quarks. These measurements suffer from very large combinatorial backgrounds and conceal the parent's kinematic properties. A suppression of particle production at high transverse momenta is likely caused by their interaction with the hot and (open full item for complete abstract)

Committee: Spyridon Margetis (Advisor); Declan Keane (Committee Member) Subjects: Experiments; High Temperature Physics; Nuclear Physics; Particle Physics; Physics; Quantum Physics

Doctor of Philosophy, University of Akron, 2017, Mechanical Engineering

The room and high temperature mechanical properties of continuous ceramic fiber reinforced matrix composites makes them attractive for implementation in aerospace and nuclear applications. However, the effect of fiber content has not been addressed in previous work. Therefore, single tow composites with fiber content ranging from 3 to 47 % was studied. Single fiber tow minicomposite is the basic architectural feature of woven and laminate ceramic matrix composites (CMCs). An in depth understanding of the initiation and evolution of damage in various ceramic fiber reinforced minicomposites with different fiber volume fractions and interphases was investigated employing several non-destructive evaluation techniques. A new technique is used to determine matrix crack content based on a damage parameter derived from speed of sound measurements which is compared with the established method using cumulative energy of Acoustic Emission (AE) events. Also, a modified theoretical model was implemented to obtain matrix stress at the onset of matrix cracking. Room temperature tensile, high temperature creep rupture and high temperature oxidation degradation loading conditions were all considered and composites' constituents were characterized. Moreover, fibers/matrix load sharing was modeled in creep and fiber volume fraction effect on load transfer was investigated using derived theoretical models. Fibers and matrix creep parameters, load transfer model results and numerical model methodology were used to construct minicomposites' creep strain model to predict creep damage of the different fiber type and content minicomposites. Furthermore, different fiber volume fractions ceramic matrix minicomposites' electrical resistivity temperature dependence isn't well understood. Therefore, the influence of fiber content, heat treatment cycles and creep on electrical resistivity measurements of SiC/SiC minicomposites were also studied here. Next, minicomposites' testing and characteriza (open full item for complete abstract)

Committee: Gregory Morscher Dr (Advisor); Tirumalai Srivatsan Dr (Committee Member); Craig Menzemer Dr (Committee Member); Alper Buldum Dr (Committee Member); Kwek Tze Tan Dr (Committee Member); Robert Goldberg Dr (Committee Member); Manigandan Kannan Dr (Committee Member) Subjects: Acoustics; Aerospace Engineering; Aerospace Materials; Chemical Engineering; Chemistry; Electrical Engineering; Engineering; Experiments; High Temperature Physics; Materials Science; Mathematics; Mechanical Engineering; Mechanics; Metallurgy; Theoretical Mathematics; Theoretical Physics

BS, Kent State University, 2016, College of Arts and Sciences / Department of Physics

I discuss the historical and physical significance of bottomonium suppression in heavy ion collision-produced quark-gluon plasma. I use a computational technique, the finite-difference time-domain method, to solve the Schrodinger equation for a complex valued potential and obtain collision temperature-dependence of bottomonium's binding energy. Along the way, I review fundamentals of quantum theory, I present a 1-dimensional algorithm for the finite-difference time-domain method, and I test outputs of that algorithm by comparing them with known analytic solutions of the Schrodinger equation for a simple potential.

Committee: Michael Strickland (Advisor) Subjects: High Temperature Physics; Particle Physics; Physics

Master of Science (M.S.), University of Dayton, 2011, Aerospace Engineering

The calculation of a recovery temperature based heat transfer coefficient proves to be sufficiently independent of wall temperature to use in a three dimensional, transient temperature model of a thermal protection system of a reusable booster concept. After a derivation of recovery temperature from the 1st law of thermodynamics, the weak dependence of the recovery temperature based heat transfer coefficient is investigated by 72 Computational Fluid Dynamics (CFD) models at angles of attack ranging from 0° to 90° over a range of Mach numbers, from Mach 2 to 5, and a variety of thermal boundary conditions at the wall, from isothermal to a conductive wall. Then, the heat transfer coefficient is calculated at many steady state CFD solutions for a reusable booster system concept on a given trajectory and applied to a transient Finite Element Analysis (FEA) model of a thermal protection system. Results are presented graphically.

Committee: Timothy J. Fry PhD (Committee Chair); Jos&#233; A. Camberos PhD, PE (Committee Member); John Doty PhD (Committee Member) Subjects: Aerospace Engineering; Atmosphere; Computer Science; Fluid Dynamics; High Temperature Physics; Mechanical Engineering