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Guo, QiA Framework for Optimal Decision Making of a Photovoltaic Recycling Infrastructure Planning
Doctor of Philosophy (Ph.D.), University of Dayton, 2017, Mechanical Engineering
Solar energy, as an emerging renewable clean energy, has been rapidly growing for 15 years all over the world and is expected to grow 15% annually until 2020. In 2015, at least 40 GW of Photovoltaic (PV) systems were installed, achieving 178GW current solar power installation worldwide. In the next five years, 540 GW cumulative capacities are expected to be installed worldwide and US contributed 6.5 GW PV installations in 2015. US electricity demand is expected to be dominated by solar power by 2050 or even earlier. The widespread deployment of PV will not only contribute to a reduction in greenhouse gas emission, but can also mitigate the worldwide fossil fuel depletion. As the number of PV systems increases, the mass of PV waste will increase as well, adding a new source to the existing waste stream. The amount of End-of-Life (EoL) PV will approach 13.4 million ton worldwide, including approximately 5.5 million ton located in the US by 2025. PV contains high value, toxic, and energy-intensive materials. In addition, the market price of some materials utilized in the thin-film and crystalline PV technologies has drastically increased in the recent years. There is a strong need of coordinating the information to optimize the reverse logistics planning in a photovoltaic (PV) recycling network in the U.S. Two major tasks are included: 1) locating PV Recycling Centers (PVRC); 2) allocating Transportation Companies (TC) shipping PV installation sites (PVIS) to PVRC. One contribution of this dissertation is to decide the optimal number, as well as the location of PVRC by minimizing the overall cost. Another contribution is to determine the optimal distribution scheme to minimize the transportation cost among TC, PVIS, and PVRC. In order to accomplish the two tasks, a mathematical modeling framework was developed to facilitate PV recycling in an economically and environmentally feasible manner. The framework included two mathematical models: 1) Multi-Facility Optimization Model; 2) Optimal Distribution Model. The multi-facility optimization model included the transportation module, the economic module, and the environmental module. The model identifies the geographical location of the prospective PVRCs by minimizing the total costs in different scenarios. While in the Optimal Distribution Model, a static and a dynamic optimization algorithm was applied for conducting the optimal solution accurately and efficiently. To show the efficacy of the proposed framework, case studies for recycling EoL PV in California were performed. Historical PV installation data in the region was utilized to gather information about the amount of the prospective end-of-life (EoL) PV waste generation in CA. In order to integrate the temporal and the spatial dispersion of PVISs in CA, a three-phase recycling plan was proposed. For well displaying the geographical results, Geographic Information System (GIS) was utilized to visualize the installation data, optimized location of the PVRCs, and the optimal distribution scheme. The proposed generic framework provided a great insight for decision makers about the trade-offs among various scenarios by considering cost, environmental impact, and investment risk on PV recycling planning.

Committee:

Jun-Ki Choi (Advisor); Chuck Ebeling (Committee Member); Ron Deep (Committee Member); Shuang-ye Wu (Committee Member)

Subjects:

Energy; Mechanical Engineering

Keywords:

PV recycling, Optimization, End-of-Life recycling framework

Hutten, Victoria ElizabethProcess Modeling of Thermoplastics and Thermosetting Polymer Matrix Composites (PMCs) Manufactured Using Fused Deposition Modeling (FDM)
Master of Science (M.S.), University of Dayton, 2017, Mechanical Engineering
In this work, a model framework for the simulation of Fused Deposition Modeling (FDM) of thermoplastic and thermosetting polymers and Polymer Matrix Composites (PMCs) was developed. A Python script was constructed to automatically generate a 3D finite element heat transfer and stress model of individual roads within a 3D printed part. The script creates the road activation sequence based on the print path specified in the part G-code and associated boundary conditions which are continuously updated throughout the analysis with minimal input from the user. Thermosetting polymers and polymer matrix composites (PMCs) are modeled by implementing a material sub-model from Convergent Manufacturing Technologies called COMPRO that captures the curing kinetics of the material during the printing and post-cure cycle. The modeling approach is formulated for both material systems through tailorable conditions such as build plate temperature, ambient conditions, print temperature, etc. To the author’s knowledge, no 3D finite element model of the FDM process exists for the thermal history and residual stress prediction of thermosetting polymers and PMCs. Although the objective of this work is to create a model for the prediction of thermosetting polymers and PMCs, the characterization and subsequent printing of these materials is still in the development stages. Therefore, in order to validate that the proposed model is capturing the correct physics for the FDM process, model predictions for Acrylonitrile Butadiene Styrene (ABS) coupons were compared with experimentally printed specimens. A series of sensitivity studies were then performed for this model to investigate significant effects as well as trends in the predictions from assumptions in the boundary conditions. The model is then extended to thermosetting PMCs to demonstrate the linkage between COMPRO and the modeling framework.

Committee:

Robert Brockman, PhD (Committee Chair); Brent Volk, PhD (Committee Member); Thomas Whitney, PhD (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

finite element analysis; process modeling; fused deposition modeling; polymer matrix composites; thermosetting polymers

Smith, GregoryAn Analysis of Critically Enabling Technologies for Force and Power Limiting of Industrial Robotics
Master of Science (M.S.), University of Dayton, 2017, Electrical Engineering
The power and force limited (PFL) industrial robot market is one that is much underdeveloped and market demand is increasing every year. A literature review of critically enabling technologies for PFL robotics is conducted to evaluate the successes and limitations of developed and emerging PFL technologies. From this analysis a one link robot testbed is developed to test and gain a deep understanding of inherent torque sensing properties. Two custom sensing configurations and two custom torque plates are also designed to evaluate key torque sensing properties. Finally, an evaluation on these results lead to conclusions of the inherent effectiveness of the selected PFL enabling technologies.

Committee:

Raul Ordonez, Ph.D (Committee Chair); Russell Hardie, Ph.D (Committee Member); Chetan Kapoor, Ph.D (Committee Chair)

Subjects:

Robotics

Keywords:

Torque Sensor; Harmonic Drive; Capacitive Sensor; Optical Encoder; Power and Force Limited

Fang, ShanpuAnalysis of Operator's Energy Savings with Wrong Estimation in Intent in an Exoskeleton System
Master of Science (M.S.), University of Dayton, 2018, Mechanical Engineering
Exoskeleton is designed to help the operator move. An exoskeleton assists the operator with movement by changing the resultant torque about the operator’s joints. To maintain high working efficiency, the exoskeleton is supposed to estimate the operator’s intent of moving and produce torque of proper amount. Since the operator’s intent is involved, considering there has not been an accurate and reliable way of determining a person’s intent of moving, assuming the exoskeleton doesn’t update its estimation towards the operator’s intent within 20 durations, we analyzed the effectiveness of an ankle exoskeleton by running simulations and computing the energy savings for the operator when the exoskeleton made wrong estimation towards the operator’s intent of moving. Based on the simulations, we reached a conclusion that, for intent estimation, the error in frequency and the error in phase have higher impact than other variables (interactions of variables) on the effectiveness of an exoskeleton.

Committee:

Timothy Reissman (Advisor)

Subjects:

Mechanical Engineering

Keywords:

exoskeleton; effectiveness; intent; energy; open loop control

Stasiak, MeganTeachers' Experiences with and Perceived Ability to Serve Students Exposed to Trauma
Specialist in Education (Ed.S.), University of Dayton, 2018, School Psychology
Children exposed to trauma may go on to experience chronic psychologic symptoms. There is an increasing need for general education teachers to recognize the signs of trauma exposure and be able to support traumatized students in the classroom. Few studies have examined the relationship between these perceptions and teachers’ previous experiences, training, and education on trauma exposure in adolescence. This study examined teachers’ experiences with and perceived ability to serve students exposed to trauma. One-hundred and fourteen general education teachers from the Midwest completed an internet survey on their experiences and perceptions; four teachers were interviewed about their experiences and perceptions. Results indicate an overall desire to aid students, and a positive relationship between pre-service trauma training and higher perceived ability to aid students exposed to trauma. There was no relationship between professional development and/or prior experience with students exposed to trauma and the teachers’ perceived ability to provide supports. Implications for school professionals when serving this population are discussed.

Committee:

Susan Davies, Ed. D (Advisor); Elana Bernstein, Ph. D (Committee Member); Jim Ayers, Ed. S. (Committee Member)

Subjects:

Education; Psychology; School Counseling

Flynn, Michaline L.Post-Secondary Transitions for Students with High-Incidence Disabilities
Specialist in Education (Ed.S.), University of Dayton, 2017, School Psychology
The transition from high school to post-secondary life is especially difficult for students with high-incidence disabilities.The purpose of the present study was to examine the educational experiences of students with high-incidence disabilities, such as ASD, specific learning disability, and ADHD, who received post-secondary transitional services. Participants included (n = 25) seniors in high school with current IEPs, who completed questionnaires regarding their experience with post-secondary transitional services and were interviewed after graduation to share their perceptions of the process and services they received to prepare them for post-secondary life Results suggest that participants perceive themselves as prepared for their post-secondary goals both before graduation and during the fall after graduation; however, they do not attribute their readiness to the services received in school. Implications for practice and future research are discussed.

Committee:

Susan Davies, Dr. (Committee Chair); Elana Bernstein, Dr. (Committee Member); Nasser Razek, Dr. (Committee Member)

Subjects:

Psychology

Keywords:

Post-Secondary Transitions; Special Education; High-Incidence Disabilities; School Psychology; High School

Li, KaiyuSupramolecular Ruthenium(II) and Osmium(II) Complexes: Synthesis, Characterization, DNA Binding and DNA Photocleavage
Master of Science (M.S.), University of Dayton, 2017, Chemistry
Two new bridging ligands have been synthesized by combining substituted benzaldehydes with phenanthrolinopyrrole (php), resulting in new polyazine bridging ligands. The ligands have been characterized by 1H NMR, mass spectroscopy, and elemental analysis. These new ligands display π-π* transitions above 500 nm with modest molar absorptivities. Upon excitation at the ligand-centered charge-transfer transition, weak emission with a maximum wavelength of 612 nm is observed. When coordinated to two ruthenium (II) bis-(2,2’-bipyridine) groups, the new bimetallic complexes generated give an overall 4+ charge. The electronic transitions of the bimetallic ruthenium (II) complexes display traditional π-π* transitions at 287 nm and metal-to-ligand charge-transfer transitions at 452 nm with molar absorptivities greater than 30000 M-1 cm-1. Oxidation of the ruthenium (II) metal centers to ruthenium (III) occurs at potentials above 1.4 V versus the Ag/AgCl reference electrode. Spectroscopic and electrochemical measurements indicate that the ruthenium (II) moieties behave independently. Both complexes are water-soluble and show the ability to photo-nick plasmid DNA when irradiated with low-energy light above 550 nm. In addition, one of the complexes, [Ru(bpy)2php]2Van4+, shows the ability to linearize plasmid DNA and gives evidence, by gel electrophoresis, of photoinduced binding to plasmid DNA. Coordination of two Osmium(II) bis-(bipyridine) complexes to the peripheral phenanthroline of (4-hydroxy-3- methoxyphenyl)diphenanthropyrromethane ligand yields the bimetallic Os(II) complex. The spectroscopic properties are similar to those of [Os(bpy)3]2+ with ligand-centered π-π* transitions in the UV region of the spectrum and three metal-to-ligand charge-transfer (1MLCT) transitions in the visible region. A broad 3MLCT is observed stretching from 550 to 700 nm with modest intensity. Binding studies with calf thymus DNA (ctDNA) show binding constants as high as 105 M–1 indicating a strong interaction of the complex with DNA. When aqueous solutions of the complex and plasmid DNA are irradiated with low-energy light for brief periods of time complete photo- cleavage of the DNA is observed. Studies indicate that the mechanism of this photoreaction requires molecular oxygen and results from both the formation of 1O2 and oxygen radicals offering multiple modes for DNA destruction.

Committee:

Shawn Swavey (Committee Chair); Kevin Church (Committee Member); Mark Masthay (Committee Member)

Subjects:

Chemistry

Keywords:

Photosensitizer; Ruthenium; Osmium; Bimetallic complexes; DNA Photocleavage

Ancona, Alexis FaithKing Arthur as Transcendent Rhetoric of Anxiety: Examining Arthurian Legends as Sociopolitical Paratexts
Master of Arts (M.A.), University of Dayton, 2018, English
As a recurring figure representative of the institution of kingship, King Arthur presents a unique rhetorical opportunity to examine sociopolitical anxieties of the Middle Ages. Because of his unique position, I propose Arthur himself is a text to be analyzed. With Arthur established as a text, specifically one of rhetorical significance, I analyze his subsequent iterations (historical and literary) as paratexts. Traditionally, paratextual analysis has involved an investigation of the literal and physical artifacts surrounding a text; however, by examining Arthur-the-figure as a text, I apply paratextual analysis theoretically. Rather than examining book bindings or author's notes, I argue Arthur's paratexts involve genre and the sociopolitical rhetoric of his authors. Through this method, I argue that Arthur is a transcendent text onto which sociopolitical anxieties are imposed, making him more than a literary figure but rather a rhetorical device of cultural memory and anxiety, particularly an anxiety of belonging. The works of Geoffrey of Monmouth, Geoffrey Chaucer, Marie de France, and Sir Thomas Malory afford both an illustration of Arthur's transcendent temporality and insights into attempts at self-actualization. Reading Arthur-the-figure as a text provides not only significant opportunities to recover marginalized narratives of medieval England, but also insight into present sociopolitical anxieties.

Committee:

Miriamne Krummel (Advisor)

Subjects:

British and Irish Literature; Folklore; Gender; Literature; Medieval History; Medieval Literature; Middle Ages; Rhetoric

Keywords:

medieval literature; geoffrey chaucer; king arthur; arthurian literature; geoffrey of monmouth; marie de france; thomas malory; le morte darthur; paratextual analysis; rhetorical analysis; social anxieties; self-actualization

Razzaghi, Hesham M.Spatial Analysis of Alcohol-related Injury and Fatal Traffic Crashes in Ohio
Master of Science (M.S.), University of Dayton, 2017, Civil Engineering
Traffic crashes are considered alcohol-related if blood alcohol concentration (BAC) of a driver or non-motorist is 0.08 grams per deciliter (g/dl) or above. This thesis analyzed various socioeconomic factors that may influence alcohol-related fatal and injury crashes in Ohio at the county level in order to determine counties that may need heightened attention in terms of enforcement and education campaigns. This study used three years of Ohio traffic crash data at the county level from 2012 to 2014 obtained from the Ohio Department of Public Safety (ODPS). The objective of this study was to explore the use of an Ordinary Least Squares (OLS) regression method in identifying factors affecting alcohol-related fatal and injury crashes in Ohio at the county level. This study was done by using Geographic Information System (GIS) in order to utilize its spatial capabilities. The model of alcohol-related fatal and injury traffic crashes was initially built with 15 independent variables that may affect alcohol-related traffic crashes such as population density and household income. The variables were divided into four groups namely crash response variables, road network variables, traffic variables, and socio-demographic variables. The Moran’s I index for residuals was almost equal to zero demonstrating that there was little evidence of any autocorrelation between each other, then OLS model was deemed adequate in modeling the data used in the this study. After removing highly correlated variables, only four variables were found to be significantly affect the rates of alcohol-related traffic crashes at the county level at a 90% confidence level. The variables found significant include percent of males in the population in the county, percent of trucks in the vehicles registered in the county, percent of licensed drivers per population in the county, and elevation range in the county.

Committee:

Deogratias Eustace (Advisor)

Subjects:

Civil Engineering

Keywords:

Spatial Analysis, Alcohol-related Traffic Crashes and Ordinary Least Squares

Alanazi, Turki Mohammed J.Electronic Protection Using Two Non-Coherent Marine Radars
Doctor of Philosophy (Ph.D.), University of Dayton, 2018, Electrical and Computer Engineering
The goal of this research is to develop a method that allows for the processing of bistatic modified non-coherent marine radar’s signals coherently, for the purpose of the warfare and electronic protection. Since the marine radar transmit signal is a non-coherent signal, it makes it difficult for the jammer to deceive the radar. Each marine radar is physically modified to work coherently and then configured to form bistatic radar. In this work, a method is presented for coherent processing of signals from a bistatic magnetron oscillator based marine radar. The feasibility of this approach was previously demonstrated for a monostatic radar through a hardware modification that allowed for capture of data and processing in PC. It is demonstrated here that operating two radars in this manner and combining their resulting signals allows for an improvement in overall detection and tracking. Our approach works by sampling the transmitted and received signals at each radar. Cross-correlations between all four combinations of transmitted and received signals are used to demonstrate the limits due to mutual interference in a bistatic/multistatic system of radars. This processing is successfully demonstrated in software, showing the potential for coherency between two marine radars. In general, bistatic coherent radars are very expensive, and this work provides a method for achieving the equivalent coherent performance using two modified non-coherent radar systems.

Committee:

Michael Wicks, PhD (Advisor)

Subjects:

Electrical Engineering

Keywords:

DRFM; electronic protection; non-coherent radar; bistatic radar; radar detection and tracking; cross-correlation

Amonson, Michael D.Multiple Charge Carrier Species and Their Effects in Photorefractive Two-Beam Coupling in Potassium Niobate
Master of Science (M.S.), University of Dayton, 2017, Electro-Optics
This thesis reports on an experiment to measure charge carrier contributions from different Fe species and their effects on beam coupling efficiency using self-pumped counter-propagating two-beam coupling in iron-doped potassium niobate KNbO3:Fe. We used multiple continuous wave lasers operating across the visual spectrum to explore charge carrier creation from various transitions. Photorefractive grating formation data was acquired and analyzed using a new theoretical model which incorporates multiple charge carrier species. Initial analysis provides supporting evidence of a multiple charge carrier model and presents new insights about the effects of various charge carriers on the photorefractive periodic space-charge fields.

Committee:

Dean Evans (Advisor)

Subjects:

Electromagnetism; Materials Science; Optics; Physics

Keywords:

Potassium Niobate; Iron Doped Potassium Niobate; Photorefractive; Multiple Charge Carriers; Two-Beam Coupling

Long, Brandon ScottEffect of Rayleigh-Taylor Instability on Fuel Consumption Rate: A Numerical Investigation
Master of Science (M.S.), University of Dayton, 2017, Aerospace Engineering
An extensive numerical investigation is conducted in order to assess the effect of Rayleigh-Taylor instability on fuel consumption rate (or flame speed). Two geometries are used for this investigation, viz., a high pressure high-g (HPHG) cavity stabilized combustor and a curved duct with a backward facing step. The former geometry is a more practical combustion system that contains liquid fuel injectors with operating conditions that mimic gas turbine cycles, whereas the latter is a canonical combustor used to study turbulent premixed flames. Reynolds averaged Navier-Stokes (RANS) and large eddy simulations (LES) are used. RANS is used for the practical combustor, and both RANS and LES are used for the canonical combustor. The combustion models used are the flamelet generated manifold (FGM) and the two-step species transport for the practical and canonical combustor, respectively. The HPHG combustor is designed to induce bulk rotational flow in the cavity, inducing centrifugal acceleration. The centrifugal force acts from the high-density reactants towards the low-density products creating a Rayleigh-Taylor instability (RTI). Rayleigh-Taylor instabilities are expected to increase the turbulent flame speed and reduce the size of the combustor by increasing the flame wrinkling and/or corrugation. Simulations at two different levels of centrifugal acceleration, and, consequently, dissimilar Rayleigh-Taylor instability were performed. It was found that the nominal g-loads are overestimating the local g-loads from the simulation because thermal expansion is not taken into account. From these simulations it was not possible to discern the effect of RTI on fuel consumption rate due to the complex physical-chemical process inherent to this combustor such as fuel vaporization, molecular mixing, spray-turbulence interaction, turbulence-chemistry interaction, and partial premixing. Therefore, gaseous premixed turbulent flames were simulated in a curved duct with a backward facing step. Two radius of curvature were used, viz., an infinite (straight duct) and a finite radius of curvature (curved duct). These combustors were operated at low and high Reynolds number (3,200 and 32,000). The computational results are compared with broadband chemiluminescence and shadowgraph images reported in the literature for similar conditions and geometries. Both RANS and LES results are in general agreement with measurements. Both experiments and simulations show that increasing the Reynolds number in both straight and curved canonical combustor the flame cannot withstand the Karlovitz number effects and the flame is positioned behind the backward-facing step. In addition, the LES results indicate that at high Reynolds number the flame blows out for the straight channel while it remains stabilized for the curved channel. This result is in agreement with the blowout data reported in the literature. On the other hand, RANS over predict the flame stabilization for the straight channel. Consequently, RANS should not be used in research involving RTI-induced blowout. In conclusion, RTI interacts with a turbulent premixed flame and its overall effect is to extend the conditions under which turbulent premixed flames can be stabilized. This improved flame stabilization is a direct manifestation that the fuel consumption rate (or flame speed) has been enhanced in order for the flame to withstand higher Karlovitz number effects induced by high Reynolds number. However, the mechanism through which RTI works on the turbulent premixed flame is not clear. A new hypothesis is proposed. The increase in RTI should increase the turbulent length scale as well as increase the Karlovitz number. The corrugated flame would withstand the higher Karlovitz number because RTI temporarily and periodically reverses the turbulent energy cascade by minimizing the potential energy of the stratified flow.

Committee:

Scott Stouffer, Ph.D. (Committee Chair); Alejandro Briones, Ph.D. (Committee Member); Brent Rankin, Ph.D. (Committee Member); Jamie Ervin, Ph.D. (Committee Member)

Subjects:

Aerospace Engineering

Keywords:

Rayleigh-Taylor Instabilities; Fuel Consumption Rate; High Swirl Combustion; High-G Combustion; Backward Facing Step Combustion

Sargent, Garrett CraigSingle-Image Super-Resolution via Regularized Extreme Learning Regression for Imagery from Microgrid Polarimeters
Master of Science (M.S.), University of Dayton, 2017, Electrical and Computer Engineering

Division of focal plane imaging polarimeters have the distinct advantage of being capable of obtaining temporally synchronized intensity measurements across a scene; however, they sacrifice spatial resolution in doing so due to their spatially modulated arrangement of the pixel-to-pixel polarizers and often result in aliased imagery. This shortcoming is often overcome through advanced demosaicing strategies that minimize the effects of false polarization while preserving as much high frequency content as possible. While these techniques can yield acceptable imagery, they tend to be computationally complex and the spatial resolution is often reduced below the native capabilities of the focal plane array. This thesis proposes a super-resolution method based upon a previously trained regularized extreme learning regression (RELR) that aims to recover missing high-frequency content beyond the spatial resolution of the sensor and correct low-frequency content, while maintaining good contrast between polarized and unpolarized artifacts presented in this thesis. For each of the four channels of the image, the modified RELR predicts the missing high-frequency and lowfrequency components that result from upsampling. These missing high-frequency components are then refined with a high pass filter and added back to the upsampled image. This provides a fast and computationally simple way of recovering missing high frequency components that are lost with current state-of-the-art demosaicing algorithms. The modified RELR provides better results than other visible band single-image super-resolution techniques and is much faster, thus making it applicable to real-time applications. The obtained results demonstrate the effectiveness of the modified RELR for a truth scenario (no aliasing resulting from undersampling) and a derived microgrid scenario (aliasing resulting from undersampling). The truth scenario shows that the modified RELR performs exceptionally better than other algorithms, however, the derived microgrid scenario demonstrates the problems that result from aliasing for single-image super-resolution algorithms. In general, for the degree of linear polarization (DoLP) image product, aliasing greatly distorts objects within a scene and none of the super-resolution algorithms could do anything to correct for it. The modified RELR showed superior performance against other super-resolution algorithms investigated at maintaining contrast between the polarized and unpolarized artifacts, which is of great importance. Future work is dedicated to coming up with fast ways to handle aliasing that is present in true microgrid imagery.

Committee:

Vijayan Asari, Ph.D. (Advisor); Bradley Ratliff, Ph.D. (Committee Member); Eric Balster, Ph.D. (Committee Member); Theus Aspiras, Ph.D. (Committee Member)

Subjects:

Electrical Engineering; Engineering

Keywords:

single image super resolution; microgrid polarimeter; machine learning; extreme learning machine

Slye, Matthew ScottHobo Noah
Master of Arts (M.A.), University of Dayton, 2017, English
In “Hobo Noah,” Claudia wakes in the middle of the night in her new apartment to find her son Noah sleeping under the dining room table. This discovery jumpstarts an examination of Claudia’s split with Terri, her long-time partner, and Claudia’s move out of the house she shared with Terri and their twin boys. As Claudia’s drinking escalates, her already fracturing family learns that they can no longer rely on her, especially when Noah is found sleeping in a neighbor’s yard at night while he is supposed to be in Claudia’s care. In “The Retarded Angel,” Sam Gerich writes the story of the boy with the shell, a human-like character with a large shell on his back, and his quest to find his family and a mysterious flashlight that was described to him by a priest. As the boy with the shell travels from town to town looking for his family and this flashlight, he meets a number of mysterious figures. An old man and his friends viciously attack the boy, attempting to rob him. A man with claws and a doctor help the boy to recover. An old woman recruits the boy into a clandestine operation that smuggles babies from one town to another. The boy with the shell eventually meets a lighthouse operator and attempts to steal the lighthouse operator’s fire starter. When the boy’s plan is foiled, he throws himself from the top of the lighthouse. He survives the fall, but his shell breaks, revealing wings underneath.

Committee:

Joseph Pici (Advisor)

Subjects:

American Literature; Gender Studies

Keywords:

twins in fiction; short story cycle; head lice; metafiction

Hussain, Mallik Mohd RaihanNonlinear Electromagnetic Radiation from Metal-Insulator-Metal Tunnel Junctions
Master of Science (M.S.), University of Dayton, 2017, Electro-Optics
Our goal was to experimentally detect nonlinear electromagnetic (EM) radiation (in the far field) from a metal-insulator-metal (MIM) tunnel junction where the insulator thickness lies in the nanometer to subnanometer range and the metals in the junction are coupled to the electromagnetic field of incident photons. The radiation from an MIM junction originated from the photon-induced tunneling current passing through it. The phenomenon is elegantly described by photon-assisted-tunneling (PAT) theory that introduces transfer Hamiltonians in the uncoupled (when two metals are at infinite distance from each other) system Hamiltonian. This theory predicts the contribution of additional conductivity terms in the MIM interface (due to tunneling inside the junction) and ushered the development of quantum conductivity theory (QCT), as a consequence. In this thesis, we reviewed QCT from the perspective of many-body formulation and designed careful experiments to detect the nonlinear electromagnetic radiation from MIM junctions that can be attributed to photon-assisted tunneling of electrons. In our experiment, first, an insulator layer was put on the metal surface using atomic layer deposition (ALD) technique. The number of layers were varied to produce MI samples with different insulator thickness in the subnanometer range. Then, we set the background signal strength by measuring the second harmonic (SH) and third harmonic (TH) signal due to the bulk material and the surface of metal-insulator (MI) interface. Next, we spin-coated the MI sample with Au nanospheres (diameter ~ 10 nm) to construct MIM interfaces and measured SH and TH signals from them again. Without any bias voltage across the MIM, QCT predicts an increase in TH signal only. Experimentally, we observed an increase in TH signal strength. The increase was modest which is partially attributed to the fact that we could not reliably produce MIM samples with subnanometer insulator thickness and uniform coverage. We intend to improve the surface coverage and uniformity of the insulator layer, in future, and measure SH and TH from the improved samples. Detection of such radiation would support QCT and validate the extension of transfer Hamiltonian approach from the realm of superconducting tunnel junctions to normal MIM tunnel junctions.

Committee:

Joseph Haus, Ph.D. (Committee Chair); Andrew Sarangan, Ph.D. (Committee Member); Imad Agha, Ph.D. (Committee Member)

Subjects:

Electromagnetics; Nanoscience; Nanotechnology; Optics; Quantum Physics

Keywords:

tunnel junction; metal-insulator-metal; MIM; nonlinear radiation from MIM; transfer Hamiltonian; photon-assisted-tunneling; PAT; quantum conductivity coefficient; QCT; Au-Al2O3-Au; atomic layer deposition on metal; ALD on metal; metal-insulator; MI

Kuebel, Laura A.Effectiveness of a Social Skills Curriculum on Preschool Prosocial Behavior and Emotion Recognition
Specialist in Education (Ed.S.), University of Dayton, 2017, School Psychology
Preschool children in public school programs are expelled at three times the rate of their K-12 peers. Research demonstrates a decreased emphasis on social-emotional skill development in preschool, despite high incidences of problem behaviors. The present study investigated the effectiveness of a commercially available social skills curriculum on preschoolers’ social-emotional development, specifically their pro-social behaviors and emotion recognition. Results showed that students who participated in the social skills curriculum increased prosocial skills and ability to visually recognize emotions in others. While statistical measures indicate that the intervention did not have a statistically significant impact on student emotion recognition and prosocial behavior, anecdotal reports from participating teachers indicated that the intervention was highly beneficial to participating students. Further, the curriculum had a high level of treatment acceptability by participants’ teachers. Implications regarding social emotional curriculum and preschool students’ prosocial skill and emotion recognition development are provided.

Committee:

Elana Bernstein (Committee Chair); Susan Davies (Committee Member); Joni Baldwin (Committee Member)

Subjects:

Curricula; Preschool Education

Keywords:

preschool; social emotional; emotion recognition; prosocial behavior; curriculum

Wagner, ChristopherRegression Model to Project and Mitigate Vehicular Emissions in Cochabamba, Bolivia
Master of Science (M.S.), University of Dayton, 2017, Renewable and Clean Energy
The purpose of this study is to generate a regression model tying the vehicular emissions in Cochabamba, Bolivia to input factors including the current state of the public fleet, city population, weather, and GDP. The finished model and the process to generate it can act as a tool to project future emissions in the city, accounting for the aforementioned input factors. It can also be used to estimate the drop in city pollution levels in a scenario where the public transportation fleet is partially replaced by non-emitting, electric vehicles. The main pollutant focused on in this study is particulate matter (PM10), but data also exists for ozone (O3), nitrogen dioxide (NO2), and sulfur dioxide (SO2). The model generation process explained in the study could be applied to these pollutants as well. The regression model is generated using the open source software, R. Its final form utilizes a random forest regression model, but neural net, gradient boosting, and support vector machine models were also explored.

Committee:

Robert Brecha, Ph.D. (Committee Chair); Andrew Chiasson, Ph.D. (Committee Member); Malcolm Daniels, Ph.D. (Committee Member)

Subjects:

Engineering; Environmental Engineering; Mechanical Engineering

Keywords:

Random Forest Model; Vehicular Fleet; Cochabamba, Bolivia; Vehicle Emissions; Predictive Ensemble Model

Yang, ZhijunIncoherent Imaging in the Presence of Atmospheric Turbulence and Refractivity
Doctor of Philosophy (Ph.D.), University of Dayton, 2017, Electro-Optics
Atmospheric turbulence, associated with its refractive-index inhomogeneities (refractivity), may severely affect long range incoherent images formation. Example of this impact includes image blurring, motion, warping and anisotropic geometrical distortions. Currently, the effects of turbulence and refractivity on image formation are considered as being mutually independent and analysed separately using the Fresnel diffraction (wave-optics) and geometrical optics (ray tracing) approaches, respectively. Such independent treatment of turbulence and refractivity effects have certain limitations. Atmospheric refractivity may result in significant deviations of optical wave propagation direction. This effect is commonly referred as the ray bending which, in turn, may lead to a change in turbulence characteristics such as the refractive index structure parameter Cn2 that is commonly considered as a function of altitude h above the ground. Correspondingly, optical wave refraction, especially in extended-range imaging scenarios, could affect the turbulence-induced optical aberrations. In this work, we analyze the incoherent image formation in atmosphere in the presence of both atmospheric turbulence and refractivity using numerical simulations based on the brightness function (BF) technique. Using the BF technique, the incoherent imaging system modulation transfer function (MTF) estimation is performed via direct numerical analysis of visibility of sine-test patterns of different spatial frequencies. The test patterns are assumed to be imaged through a volume medium with turbulence and refractivity-induced refractive index inhomogeneities. The major effects observed in numerical simulations, include the spatial frequency shift between frequency of a sine-test object and its image, and spatial non-uniformity of the sine-pattern image distortion which is referred as the refractivity-induced image anisoplanatism. Both effects depend on the location and strength of the localized refractive index structure with respect to the imaging (wave propagation) geometry. The MTFs corresponding to distributed (volume) turbulence with and without atmospheric refractivity are also compared. Next, the joint impact of atmospheric turbulence and inverse temperature layer (ITL) on optical mirage formation is analyzed. The dependency of both desert- (superior) and ocean-type (inferior) mirage image formation on ITL characteristics (temperature inversion and location of the ITL) have been studied. The impact of atmospheric turbulence strength on mirage image qualities is also analyzed. Finally, a numerical analysis is conducted to study the impact of localized refractive index inomogeneites on image quality. It is shown that image quality strongly depends on atmospheric turbulence strength and locations along the optical path. To characterize this impact, two metrics are proposed and developed to measure the image quality as a function of turbulence strength and location. The impact of inverse temperature layer on the developed image quality metrics are also studied.

Committee:

Mikhail Vorontsov (Advisor); Partha Banerjee (Committee Member); Edward Watson (Committee Member); Steven Fiorino (Committee Member)

Subjects:

Atmospheric Sciences; Engineering; Optics

Keywords:

incoherent imaging; atmospheric turbulence; refractivity; modulation transfer function; optical mirage

McDaniel, Sean A.Mid-IR Ultrafast Laser Inscribed Waveguides and Devices
Doctor of Philosophy (Ph.D.), University of Dayton, 2017, Electro-Optics
Ultrafast laser inscription (ULI) is a highly versatile technique for creating index modifications in glasses and crystalline materials. The process of ULI relies on ultrashort laser pulses focused inside of a material. The high intensity of the pulsed beam induces nonlinear absorption processes, which transfers the pulse energy to the material lattice. With careful experimental control of the laser parameters, a permanent change in the refractive can be obtained in the bulk material. The permanent refractive index change obtained by ULI can be used to create waveguides in active laser materials, such as Cr:ZnSe, Fe:ZnSe and Ho:YAG. Transition metal and rare-earth laser sources have been shown to operate over the 2 - 5 micron range. ULI can be used in conjunction with these materials to produce high power, guided-wave structures with reduced size, weight and power (SWaP) requirements. Power levels for Cr:ZnSe and Fe:ZnSe have been scaled to > 5 W and > 1 W respectively in ULI waveguide devices. Additionally, the first Ho:YAG ULI laser has been investigated, exhibiting output powers of ~ 2 W. In addition to these advances, the theoretical limit for transition metal waveguide lasers was investigated. Transition metal lasers are highly sensitive to the operating temperature of the laser device. If the temperature increase induced in the sample is too high, phonon assisted transitions become dominant, thus decreasing the performance of the laser. Laser rate-equations and a thermal model for ULI waveguides were developed to establish a theoretical limit to ULI waveguide operation. Finally, several advancements were made with respect to creating ULI waveguides. An algorithm was developed for creating arbitrary ULI structures from computer generated models. The ability to create arbitrarily generated structures provides the ability to create complex structures using ULI, such as splitters, couplers, and photonic lanterns. Furthermore, a new helical inscription technique was devised for creating smooth index profiles and for creating Bragg structuring.

Committee:

Gary Cook, Ph.D. (Committee Chair)

Subjects:

Engineering; Optics

Keywords:

Waveguide; Mid-IR Lasers

Miser, Rachael SpikerA Phenomenological Study of Secondary Teachers' Experiences with Assessing Higher Order Thinking Skills
Doctor of Philosophy (Ph.D.), University of Dayton, 2017, Educational Leadership
The study explored the experiences of seven effective high school teachers in assessing higher order thinking skills. For students to graduate an Ohio public school, they are to have the resources and skills to be college and career ready and according to the Ohio Learning Standards and developing higher order thinking is part of this mandate. Because of these demands, increased focus and attention is being directed to the development of knowledge beyond basic recall and rote memorization and towards deeper understanding, critical thinking, and problem solving. The methods used for this study were based on a qualitative phenomenological design that used a social constructivist framework and an ontological philosophical basis. Seven teachers from an Ohio secondary public-school district were the participants. Empirical data were collected through in-depth interviews and analysis of the data was through horizonalizing and finding themes, developing textural descriptions, and deriving meanings and essences. Twelve themes were constructed--internal classroom themes of defining higher order thinking, questioning, collaborative groups, problem and project based learning, demonstration of skills, instilling confidence, time; and external themes of administrators, professional development, teacher training, Common Core or Ohio Learning Standards, and collaboration with other teachers.

Committee:

Carolyn Ridenour (Committee Chair)

Subjects:

Education; Educational Leadership

Keywords:

phenomenology; assessing; higher order thinking skills; experiences of secondary teachers

Patterson, Erin LeighCompression of Medical Images Using Local Neighbor Difference
Master of Science (M.S.), University of Dayton, 2017, Electrical Engineering
Medical images are an essential part to any health professional’s career when helping patients and diagnosing health concerns. Due to the need for large storage capacity and fast transferring speed, research in image compression has grown. Image compression uses the property of redundant information in the image to reduce the amount of data in the image to solve both problems of storage and transmission. For medical images, lossless compression algorithms are of interest to make sure that the reconstructed image provides the same details as the original image. This thesis presents a proposed algorithm called the Local Neighbor Difference (LND) which is a preprocessing technique to allow the redundancy in the medical image to be reduced before being sent into a commercial-off-the-shelf compressor (COTS), XZ. LND, when used in conjunction with XZ losslessly, compresses images, on average, by 6% more than XZ alone. The LND process, along with some future work, is proposed in this paper and results in a viable option for a pre-process to a compressor.

Committee:

Eric Balster, Dr. (Advisor)

Subjects:

Electrical Engineering

Keywords:

medical images; lossless; image compression; XZ;

Elmushyakhi, AbrahamIn-Plane Fatigue Characterization of Core Joints in Sandwich Composite Structures
Doctor of Philosophy (Ph.D.), University of Dayton, 2017, Materials Engineering
In practice, adjacent preform sandwich cores are joined with a simple butt joint without special precautions. When molded, this gap is filled with resin and creates a resin rich area. Stress risers will be amplified under cyclic load, and consequently, the serviceability of the structure will be affected. Designers and researchers are aware of this problem; however, quantifying this effect and its intensity and consequence on the service life of the structures has not yet been developed. Despite pervious findings, limited experimental data backed by a comprehensive root cause failure analysis is available for sandwich under axial static, fatigue and post-fatigue. If such a comprehensive experimental characterization is conducted, specifically understanding the nature of the damage, intensity, and residual strength, then a valid multi-scale damage model could be generated to predict the material state and fatigue life of similar composite structures with/without core joints under in-plane static and fatigue load. This research study characterized the effect of scarf and butt core joints in foam core sandwich structures under in-plane static and fatigue loads (R=0.1 and R= -1). Post-Fatigue tensile tests were also performed to predict the residual strength of such structures. Nondestructive Evaluation Techniques were used to locate the stress concentrations and damage creation. A logical blend of experimental and analytical prediction of the service life of composite sandwich structures is carried out. The testing protocol and the S-N curves provided in this work could be reproducible and extrapolated to any kind of core material. This research study will benefit composite engineers and joint designers in both academia and industry to better apprehend the influence of core joints and its consequence on the functionality of sandwich structures.

Committee:

Elias Toubia (Advisor); Paul Murray (Committee Member); Thomas Whitney (Committee Member); Youssef Raffoul (Committee Member)

Subjects:

Aerospace Engineering; Aerospace Materials; Civil Engineering; Composition; Design; Engineering; Materials Science; Mechanical Engineering; Polymers

Keywords:

Sandwich Composite Structures; Design; Fatigue; Damage; Joints; Lightweight Materials; E-glass-vinyl ester; GFRP Laminate; Modeling; Prediction; Nondestructive Testing

Abdelhafeid, FarajThe Effect Upon Antenna Arrays of Variations of Element Orientation and Spacing in the Presence of Channel Noise, with an Application to Direction Finding
Doctor of Philosophy (Ph.D.), University of Dayton, 2018, Electrical and Computer Engineering
This work introduces the developments of a modified Min-Norm method to determine the AoA of an unknown signal incident upon an arbitrarily spaced array of randomly oriented elements in conjunction with a linear phase interferometer to accommodate large element spacing. This method is then applied to arrays comprised of two distinct element types via the use of MATLAB code written expressly for this purpose. The CRLB for both the original Min-Norm AoA estimator and the modified Min-Norm AoA estimator is derived. This dissertation aims to design a direction finding system that uses a volumetric, arbitrarily oriented and spaced antenna array and examines the perturbation effects of the orientation and position of the antenna elements on the accuracy of the estimated Angle of Arrival (AoA). The perturbation of the antenna elements is represented by six parameters: three parameters for element position and three parameters for element orientation. The impact of the polarization mismatch between the incident signal and the antenna elements that occurs when the array contains many antennas with various orientations have been taken into consideration in this work. If not accounted for, these effects can severely affect the accuracy of the direction-finding systems. First, an expression for the electric field in the far-field zone was derived using a volumetric array of arbitrarily oriented and spaced short dipoles using the Integral Equation Method and a volumetric arbitrarily-oriented and spaced pyramidal horn array using the Euler Method. Then, the Min-Norm AoA estimation method is modified through the Standard Lagrange Optimization Method to accommodate variations in the array signal vectors caused by perturbation of the orientation and position of the antenna elements. This method is selected due to its ability to address the side effect of averaging the pseudo-spectrum in the MUSIC Method, in which the peaks corresponding to the direction of the actual incident signal decreased in amplitude, and some spurious peaks appeared in the pseudo-spectrum. A linear phase interferometer, using an array of diversely polarized, relatively wide inter-element spaced pyramidal horn antennas was combined with the proposed AoA estimation method to utilize the advantages of both approaches to minimize the Root Mean Square Error (RMSE) of the estimated AoA. The proposed AoA estimation method has the advantage of being robust against the effects on the received signal associated with the perturbation of the orientation and position of the antenna elements and the polarization mismatch between the antenna elements and the incident signals. The linear phase interferometer eliminates the ambiguous AoA solutions associated with the phase wrapping at the relatively large inter-element spacing. The proposed AoA estimation method is investigated using different antenna types and various array configurations at random perturbation of the antenna position and orientation. Elevation and azimuth AoA estimation are combined to establish a single figure of merit for the system. The RMSE of the estimated angle of arrival is calculated from 2000 iterations of a Monte-Carlo simulation. Simulations verify that the modified AoA estimation method provides improved performance compared with the standard Min-Norm Method in terms of RMSE of the estimated AoA. The effect of perturbation of antenna orientation and position on the elevation and azimuth AoA estimation were compared in terms of a range of incident elevation and azimuth directions.

Committee:

Robert Penno, Prof (Advisor)

Subjects:

Electrical Engineering

Keywords:

Angle of Arrival, Antenna Array, Orientation, Position, RMSE

Wetter, Sara ElizabethExamining Sleep as a Protective Mechanism for Executive Functioning in Children from Low-Income Homes
Master of Arts (M.A.), University of Dayton, 2018, Psychology, Clinical
For young children, sleep is essential for healthy development across a wide variety of areas. Inadequate sleep can affect emotional, behavioral, cognitive, and health outcomes in early childhood, and can lead to poor outcomes later in life. Low family income and resources can put children at risk for poor sleep quality, impairing their subsequent cognitive abilities, particularly those related to executive functioning. While sleep in early childhood and its effects on executive functioning have been studied, the interaction between family income and sleep habits and their associations with cognitive functioning is less well known. The current study examined sleep quality as a protective factor against the negative effects of low socioeconomic status (SES) on children’s executive functioning skills, specifically those of working memory and inhibition. It was hypothesized that SES would moderate the association between children’s sleep quality and executive functioning such that children from low-SES homes would display worse executive functioning skills when experiencing poor sleep quality. This study examined these associations by drawing from a large data set collected for a preschool expansion project in the Midwest. Parents filled out surveys related to their children’s sleep habits (quality and quantity) and executive functioning, as well as demographics questionnaires determining family income, children’s age, and gender. Poor sleep quality and low family income were associated with poorer performances in both working memory and inhibition. The association between sleep quality and working memory was specific to children from low-SES homes. Exploratory analyses revealed that sleep length was not associated with either working memory or inhibition. Additionally, sleep quality and family income were not associated with a direct assessment of executive functioning. These results suggest that good sleep quality could buffer against poor executive functioning skills for children from low-SES homes. Future studies should attempt to measure these associations longitudinally so as to determine causal links between these variables.

Committee:

Mary Fuhs, Ph.D. (Advisor); Jackson Goodnight, Ph.D. (Committee Member); Keri Kirschman, Ph.D. (Committee Member)

Subjects:

Clinical Psychology; Developmental Psychology; Health; Psychology

Keywords:

Executive functioning; Sleep; Protective mechanism; Low-income; Early childhood

Parker, Chelsey NicholeMindfulness for More: Piloting a Mindfulness Program for Underserved Populations
Master of Arts (M.A.), University of Dayton, 2018, Psychology, Clinical
Interventions engaging individuals in mindfulness practices and activities are being used to improve a variety of physical and mental ailments in many different populations. The body of research on mindfulness is rapidly growing. However, there is a notable lack of research regarding the utilization of mindfulness-based interventions among some of the most stressed populations such as those with insecure housing. Conducted within the context of an ongoing participatory community action research project (“Behavioral Activation Research Project in Homeless Shelters”), which has been a collaboration between the University of Dayton and St. Vincent de Paul in Dayton, Ohio (Reeb et al., 2017) since 2012, this study piloted a new mindfulness program in two gateway facilities utilized by men and women with insufficient housing. Although the focus of this study was on the development of the program and testing it’s feasibility, mixed model, repeated measure ANOVAS were used to determine if state anxiety from pre- to post- intervention within each shelter, as well as by type of first session attended. Result suggested that participating in a single mindfulness session decreased state anxiety for participants, implicating that benefits are received from a single mindfulness practice.

Committee:

Jacob Burmeister, PhD (Committee Chair); Roger Reeb, PhD (Other); Eric O'Mara, PhD (Other)

Subjects:

Clinical Psychology; Psychology

Keywords:

Mindfulness; Homelessness; Underserved Populations; Meditation

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