Ph.D., Antioch University, 2024, Leadership and Change

In higher education, the focus on student success often takes center stage in research and the professor-as-teacher practice. While numerous empirical studies concentrate on the growth and development of undergraduate students, this dissertation delves into professors' relational and felt experiences in positive teaching-learning relationships. Four terminal-degreed professors from four different schools and three different disciplines–education, humanities, and leadership–engaged in photography and were then interviewed. Participants reflected on their photographs and their experiences in a teaching-learning relationship with their students. The present study aimed to illuminate the unspoken language of connection by utilizing interpretive phenomenology and photovoice to uncover professors' relational and felt experiences and how these moments energize and rejuvenate them. Research revealed two overarching themes: generativity and seeing students' humanity; and five group experiential themes: foundational influences, relational proximity, intentional presence, assessment as a learning conversation, and feeling aligned. The theoretical foundation of this dissertation weaved together a diverse array of theories and concepts, including relational cultural theory (RCT), somatics, and embodiment. The insight from the literature combined with the findings from this study offer understanding in how professor-student relationships in higher education can be places of mutual empowerment, empathy, and mattering. By grounding the research framework in human interaction's relational and fluid, alive, and pulsating bodies, this dissertation contributes to a more humanized and inclusive understanding of the intricate relationships that shape higher education. This dissertation is available in open access at AURA (https://aura.antioch.edu) and OhioLINK ETD Center (https://etd.ohiolink.edu).

Master of Science (MS), Ohio University, 2024, Environmental Studies (Voinovich)

More than half of extremely poor Nigerians live in rural areas where the deprivation of access to basic social infrastructure such as access to reliable electricity is at its highest. About 140 million Nigerians, or around 71% of the population, do not have access to energy. Bridging Nigeria's energy deficits with a net zero target and lifting millions of Nigerians out of poverty requires enormous resources from diversified energy mix such from renewable energy and technical knowledge that cannot be sourced locally. Nigeria needs to explore encourage and maintain international bi-lateral and multilateral relationships as avenues to tap international development assistance in the form of aid and foreign direct investments for renewable energy. International development partners like the GIZ have worked in Nigeria since 1974, and operated country offices in Nigeria's capital since 2004. GIZ's projects have provided advisory services to enhance access to, use of, and investments in renewable energy, energy efficiency, and rural electrification in order to address the problem of irregular power supplies. This assistance includes the twin goals of increasing access to solar energy and to reduce carbon emissions. This thesis evaluates whether GIZ-supported efforts have increased access to renewable energy, and reduced carbon emissions. The research found out that GIZ investments have contributed indirectly to increasing renewable energy access in Nigeria between 2015 and 2022 with no evidence of carbon emissions' reduction.

Master of Science in Mechanical Engineering, Cleveland State University, 2024, Washkewicz College of Engineering

Methods are being studied to help reduce the impacts of climate change, and an intermediate solution using hydrogen energy obtained from methane decomposition. This process has advantages over steam reforming of methane, which is the primary method of hydrogen production currently. It is important to model the decomposition to allow for easier use of the modeling software by others in the field looking to advance this technology. CHEMKIN is used for the modeling. The thermal decomposition is first modeled, using available reaction mechanisms and experimental data. The Appel reaction mechanism is found to have the preferred modeling capability and accessibility, but there is a significant error with hydrogen and acetylene yields which require improvement before it can be used for predicting large-scale decomposition. The mechanism is applied to a plasma reactor to test versatility, but the results are found to be inaccurate, indicating specific mechanisms will likely be required for plasma reactors. The modeling is then expanded to a more complex level, including carbon catalyst for catalytic decomposition. With no prior modeling process found for CHEMKIN, steps are taken to produce accurate modeling results compared to experimental data and modeling performed with proprietary code to ensure accuracy in the modeling process when using carbon black catalysts. Then, the process is expanded to a plasma-generated carbon to compare it to the carbon black catalysts. The results indicate that the modeling procedure is accurate and repeatable, which opens up an option for further research to be done with this software to push this process to larger scale. Additionally, by modeling extended decomposition runs, the plasma carbon is verified to outperform two of the carbon blacks, but the performance against BP2000 is inconclusive with available data, and it is deactivated more slowly but has a greater reduction in the percent reduction in hydrogen output from the initial conve (open full item for complete abstract)

Master of Science in Engineering, Youngstown State University, 2024, Department of Mechanical, Industrial and Manufacturing Engineering

This research investigates the optimization of vertical axis wind turbine (VAWT) systems to harvest energy from vehicle-induced highway winds. The primary objective is to enhance the efficiency of small-scale VAWTs mounted on the side of highways, enabling the generation of electrical energy or clean hydrogen production. Computational fluid dynamics (CFD) modeling was employed to systematically optimize the turbine design and to develop wind guides that further increase the efficiency. The study found that an elliptical VAWT design demonstrated a 4.4% higher power coefficient compared to a Savonius VAWT. Introducing a single flat or curved guide between the turbine and the road increased the power output by 145.33%. Further refinements, including the use of three guides with optimized angles and radii, culminated in a remarkable 393.16% improvement over the initial non-guided-guided configuration. In the non-guided-guided scenario, simulating the VAWT's exposure to the wake flow induced by a bus traveling at 32 m/s, the CFD analysis predicted an energy output of 30.41 Nm. However, when the three guide vane configuration was employed, the energy output exhibited a substantial increase, reaching 100.41 Nm under the same bus speed conditions. The comparative analysis between the Non-guided-guided and three-guide vane setups for the bus wake simulations revealed a remarkable 230% enhancement in energy capture when the guide vanes were incorporated. This significant performance improvement highlights the favorable impact of the optimized guide vane arrangement on the aerodynamic behavior of the VAWT, facilitating more effective extraction of energy from the wake flows generated by larger vehicles such as buses. The results showcase the significant potential of vehicle-induced highway winds as a viable source of renewable energy. The optimized VAWT system, incorporating multiple flow guides, demonstrates the ability to effectively harness this untapped resourc (open full item for complete abstract)

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

There is a continuous thrust for cleaner and more sustainable alternatives for energy conversion with the increasing global energy demand. Among them, photovoltaics, specifically thin film solar cells are highly promising and are one of the fastest growing clean energy technologies in the United States. This research presents the synthesis and characterization of a set of novel multinary copper chalcogenide semiconductor nanocrystals (NCs), CuZn2ASxSe4-x consisting primarily of earth-abundant elements for applications in photovoltaic devices. A modified hot-injection method was used to synthesize these semiconductor NCs containing both S and Se chalcogens. The novelty of the new semiconductor NCs lies in the incorporation of multiple cations as well as two different chalcogen anions within the crystal lattice, which is an achievement from the materials synthesis aspect. The composition-controlled optical and photoluminescence properties of the CuZn2ASxSe4-x NCs were investigated via multi-modal material characterization including x-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, and photoluminescence spectroscopy (PL). The crystal structure, as determined from the XRD primarily consisted of the metastable wurtzite (P63mc) phase. The NCs exhibited direct band gap in the visible range that could be tuned both by varying the group III cation within the composition as well as the ratio of S/Se, based on the Tauc plot obtained from the UV-vis characterization. This work lays the groundwork for future investigations into the practical applications of copper chalcogenide NCs in solar energy conversion.

Master of Science, Miami University, 2024, Mechanical and Manufacturing Engineering

A new method is proposed to mitigate ice accretions on wind turbine blades via the creation of a microstructural gradient surface geometry that facilitates spontaneous water droplet motion along the surface. The wettability gradients are formed by laser etching 35𝜇m wide, 35𝜇m deep channels into aluminum to form a surface with a gradually increasing solid area fraction. Different design permutations are then proposed and systematically evaluated on the merits of their performance. An analytical model is also derived based on a balance of hysteresis and drag forces to predict the critical airspeed necessary for droplet movement as a function of the droplet size and surface contact angle. Experimentation has shown good agreement with the model for both the baseline and fixed-pitch channel surfaces and has also demonstrated that, in certain cases, up to 70% lower critical airspeeds are needed to initiate droplet motion on these microstructured surfaces. Finally, the effects of frozen droplets on aerodynamic performance were studied via 3D-printed airfoil prototypes. This work demonstrated that at airspeeds under <15m/s and angles of attack between 0 – 20 degrees, frozen droplets on the top surface of the airfoil can be used to strengthen the lift-to-drag ratio by up to 184

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)

Doctor of Education , University of Dayton, 2024, Educational Administration

The research undertaken was a qualitative grounded action research case study. The researcher had the opportunity to work as part of a team seeking to alleviate energy-burdened neighborhoods within a southeastern State. The team was formed from members of the city, county, the federal government, and local not-for-profit organizations. The research questions were twofold. First, what were the project team members' initial individual approaches to achieving the project's goals of clean energy, addressing energy burdens, and community resiliency? Second, how do the team members reach a consensus over time toward achieving the project's goals? As part of the consensus building, how much of a sense of community is developed amongst the members of the team? The theoretical framework that this research was performed under was a sense of community comprised of four elements: membership, influence, reinforcement, and shared emotional connection (McMillan & Chavis, 1986). A literature review was conducted to identify initial themes that were further developed through focus groups and interviews. Two focus groups were held that involved a total of three unique members of the team per focus group who were asked the same semi-structured questions. As a follow-up to the focus groups, four participants were asked to participate in one-on-one interviews to develop further data revealed by the focus groups. The resulting data was then coded, and themes were generated from the analysis. The three themes identified through the analysis involved the Bringing Energy Efficiency Home team members' knowledge (or lack thereof), perceptions, and their bonding and sense of community. Where knowledge leads to perception and the development of a sense of community within the team the recommended course of action identified by this research is the development and implementation of a public-facing website. The development and implementation of the website will lead to readily accessible i (open full item for complete abstract)

Master of Science (M.S.), University of Dayton, 2023, Mechanical Engineering

Particle systems for concentrating solar applications present a non-trival challenge to adequately model with DEM software. A compiled modeling suite for radiative exchange, coined DEM+, is directly integrated into commercial software Aspherix®. A presentation of this modeling suite, advantages, and disadvantages is followed by an expanded look at the Distance Based Approximation (DBA) method for estimating particle-particle and particle-wall radiative exchange of more realistic particle size distributions and some simple binary mixtures. In addition, design, operation, and preliminary experimental results for a lab-scale multi-stage falling particle curtain are evaluated with particle image velocimetry (PIV) from two perspectives with discussion of the challenges therein. A room temperature DEM model of investigated particles is compared to experimental results with emphasis on future work for material calibration for DEM+.

Master of Science in Renewable and Clean Energy Engineering (MSRCE), Wright State University, 2023, Renewable and Clean Energy

In the past several years, the energy sector has experienced a rapid increase in renewable energy installations due to declining capital costs for wind turbines, solar panels, and batteries. Wind and solar electricity generation are intermittent in nature which must be considered in an economic analysis if a fair comparison is to be made between electricity supplied from renewables and electricity purchased from the grid. Energy storage reduces curtailment of wind and solar and minimizes electricity purchases from the grid by storing excess electricity and deploying the energy at times when demand exceeds the renewable energy supply. The objective of this work is to study the generation of electric power with wind turbines and solar panels coupled to either battery energy storage or hydrogen energy storage. So that logical conclusions can be drawn on the economic effectiveness of battery and hydrogen energy storage, four scenarios are analyzed: 1) purchasing all required electricity from the grid, 2) generating electricity with a combined wind and solar farm without energy storage, 3) generating electricity with a combined wind and solar farm with battery energy storage, and 4) generating electricity with a combined wind and solar farm with hydrogen energy storage. All four of these scenarios purchase electricity from the grid to meet demand that is not met by the renewable energy power plant. All scenarios are compared based on the lowest net present cost of supplying the specified electrical loads to serve 25,000 homes in Rio Vista, California over 25 years of operation. The detailed economics and electric power production of both wind and solar combined with energy storage for any size of wind facility, solar facility, battery facility, and hydrogen facility are analyzed with a MATLAB computer program developed for this work. The program contains technical and economic models of each of these systems working in different combinations. Current equipment c (open full item for complete abstract)

Master of Science (MS), Ohio University, 2023, Environmental Studies (Voinovich)

This study explores the concept of agrivoltaics, which combines agricultural practices with photovoltaic (PV) systems, with the goal of increasing economic value for farmers while mitigating land use competition. The study specifically focuses on assessing the crop performance and microclimate impacts of ginger and kale under PV arrays. An experiment was conducted at the Ecohouse on the campus of Ohio University, where a solar array was previously installed, to examine the influence of solar panels on the growth and development of ginger and kale crops. Relationships were resolved between crop growth and various environmental factors, including light availability, soil moisture, humidity, precipitation, temperature, and soil nitrogen and soil carbon content. The findings revealed that while the solar panel treatment led to lower light availability, it did not significantly affect photosynthetic rates or yield in kale plants. The shading from the solar panels positively impacted soil moisture, providing a more favorable growing environment for both ginger and kale. Temperature variations were minimal under the solar panels, indicating that agrivoltaic systems can be implemented without adverse effects on temperature conditions. The results also indicated that shading affected the growth and morphological features of ginger and kale, including leaf numbers, plant height, and the number of senesced and healthy leaves. Shading generally resulted in a reduction in leaf numbers, plant height, and root mass in ginger, while kale showed contrasting effects depending on the specific row. However, shading consistently led to a decrease in senesced leaves and an increase in healthy leaves for both crops. These findings suggest that, for some crop species, shading by solar panels can create a favorable microclimate, mitigating the negative impacts of excessive sunlight and promoting crop health.

Master of Science (MS), Ohio University, 2023, Environmental Studies (Voinovich)

Miscanthus x giganteus (miscanthus) is considered an ideal biomass energy crop because of its carbon (C) sequestration potential, water use efficiency, and low fertilizer requirements. Few US studies have measured long-term C sequestration of miscanthus on marginal lands on a decadal scale, and none have been conducted in southeast Ohio. The objective of this study was to measure the potential for C sequestration on abandoned agricultural land, the change in plant and soil nitrogen (N) over a decade, and the photosynthetic capacity in the tenth year of growth. The results revealed that after a decade, C was accumulated in the soil and the sequestration rates were estimated to be 0.20 Mg C ha-1y-1 and 0.54 Mg C ha-1y-1. However, the amount of C accumulated in the miscanthus plots were not statistically different from the adjacent unmanaged plots. There was also no statistically significant change in the amount of N in the baseline soils and after tillage and plowing when compared to the tenth year of growth. There was no statistically significant change in the amount of N found in plants over seven years, but variability in plant N was greater in some years relative to others. Even though the crop of miscanthus was grown without N fertilizers in this study, soil N at 0-30 cm depth was not depleted. There was no difference in plant C between sites, but the C concentration in stem tissue was statistically different over seven years. The photosynthetic capacity of miscanthus measured in this study indicated that the plants were thriving, and C assimilation for growth was consistent with the findings of prior work that evaluated the maximum photosynthetic rates of this species. The combination of soil C sequestration and sustained soil N over a ten-year period has important implications for the sustainability of biomass crops. Ultimately, this study addresses the net environmental benefit of using a perennial grass as a dedicated biomass crop on abandoned agricultural l (open full item for complete abstract)

Master of Science in Chemistry, Youngstown State University, 2023, Department of Biological Sciences and Chemistry

Metal oxide semiconductor materials such as tungsten oxide are promising candidates for use as photoanodes in solar water splitting. Tungsten oxide is an n-type semiconductor that was prepared on stainless steel 304 substrate and subsequently studied for water-splitting applications. This study investigated the effect of the annealing temperature and substrate cleaning reagents on the photoelectrochemical (PEC) properties of tungsten oxide thin films. The main method of synthesis employed was the sol-gel method. Tungsten oxide thin films were deposited from a precursor solution of peroxotungstic acid by doctor blading. The as-deposited amorphous WO3 films were further subjected to heat treatment at various annealing temperatures (200 ℃, 300 ℃, 400 ℃, and 500 ℃) to transform the amorphous material into polycrystalline WO3 nanostructures. Surface morphology, the crystallinity of the film, the thickness of the film, and photoelectrochemical properties were investigated using scanning electron microscopy, (SEM), X-ray diffractometry (XRD), stylus profilometry, cyclic voltammetry (CV), and linear sweep voltammetry (LSV). The optimal WO3 film, at a thickness of 5 µm and annealed at 400 ℃, achieved a photocurrent density of 98.0 µA/cm2 at an applied voltage of 0.53 V vs Ag/AgCl. It is essential to treat the substrate with HNO3 to passivate the surface of the stainless-steel substrate with the Cr2O3 layer.

Doctor of Philosophy, The Ohio State University, 2023, Electrical and Computer Engineering

This dissertation addresses energy-efficient operations for a fleet of diverse electrified vehicles at two system levels, the single-vehicle powertrain system, and the multi-vehicle transportation system, contributing to both with optimal control- and heuristic-based integrative approaches. At the single vehicle powertrain level, an electrified powertrain exhibits a continuum of complexities: mechanical, thermal, and electrical systems with nonlinear, switched, multi-timescale dynamics; algebraic and combinatorial path constraints relating a mix of integer- and real-valued variables. For optimal energy management of such powertrains, “PS3” is proposed, which is a three-step numerical optimization algorithm based on pseudo-spectral collocation theory. Its feasibility, convergence, and optimality properties are presented. Simulation experiments using PS3 on increasingly complex problems are benchmarked with Dynamic Programming (DP). As problem size increases, PS3's computation time does not scale up exponentially like that of DP. Thereafter, PS3 is applied to a comprehensive 13-state 4-control energy management problem. It saves up to 6% energy demand, 2% fuel consumption, and 18% NOx emissions compared to coarsely-modeled DP baseline. For generalizability, parallel and series electrified powertrain architectures running various urban delivery truck drive cycles are considered with multi-objective cost functions, Pareto-optimal study, energy flow analyses, and warm versus cold aftertreatment-start transients. At the multi-vehicle fleet level, energy-efficient vehicle routing approaches lack in integrating optimal powertrain energy management solutions. Extending single vehicle PS3 algorithm for a multi-vehicle fleet of plug-in hybrid (PHEV), battery electric (BEV), and conventional engine (ICEV) vehicles, an integrative optimization framework to solve green vehicle routing with pickups and deliveries (PDP) is proposed. It minimizes the fleet energy consumption a (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2023, Animal Sciences

The finite nature of natural gas, in addition to environmental and health issues arising from the burning of fossil fuels, have propelled increased interest in the development of renewable and clean alternative energy sources. Biofuels, and specifically, biobutanol production through ABE fermentation is a promising means of achieving the goal of replacing fossil fuels with a renewable energy source in the short term. However, the low yield and productivity of the butanol-producing fermentation workhorse, Clostridium beijerinckii, is a major impediment to the commercialization of biobutanol production. Extensive metabolic engineering efforts have been made to generate an industrially applicable strain; however, success has been limited. The large genome, complex metabolic and regulatory networks, and the abundance of hypothetical proteins in C. beijerinckii, in addition to the limited success obtained with metabolic engineering efforts, indicate there could be new unidentified butanol production determinants in C. beijerinckii. Therefore, this study explored the use of a ribozyme-based approach as a reverse genetics tool to identify unknown genetic determinants of butanol production in C. beijerinckii. Using Gibson assembly, the Escherichia coli-Clostridium shuttle plasmid carrying the E. coli RNase P (M1 RNA) sequence and syntheized external guide sequences (GS) were assembled, to generate a plasmid library of customized M1-based ribozyme-guide sequence (GS) constructs. The M1GS library was generated to target 31 genes that code for hypothetical proteins, which are among the 100 most expressed genes during the transition from acidogenesis to solventogenesis in C. beijerinckii. Generated customized M1GS plasmid library was used to transform C. beijerinckii to generate individual transformants with targeted mRNA degradation. With selective (antibiotics) medium, high performance liquid chromatography and spectrophotometric assays, transformants with various growth and (open full item for complete abstract)

Master of Music (MM), Ohio University, 2022, Music Therapy (Fine Arts)

Adult individuals seeking non-pharmacological, therapeutic support for situational mental health challenges have emerged as a population group that is unrecognized and underserved by the mental healthcare system in the US. Music therapy is known as a beneficial treatment modality for these individuals, but accessible treatment methods for this group of consumers is narrowly represented in music therapy literature. This case exploration was conducted to gain insight into the experiences of one member of this population as she engaged in a series of music therapy sessions involving reflexive, participant-led therapeutic music experiences facilitated by a supportive music therapist. The clinician, who was also the primary investigator in this study, employed research methods based in transcendental phenomenology during collection and analysis of rich, descriptive data. The research process ultimately resulted in synthesis of the essential, structural elements of a phenomenon that emerged organically from the participant's therapeutic process. The essence of the phenomenon, Therapeutic Change, is defined by the intersection of Awareness, Control, and Connection within the therapeutic space. The researcher discusses implications of these findings and makes recommendations for development and future implementation of a new, integral model of music psychotherapy that emerged as a result of this work, called Insight-Oriented Music Facilitated Psychotherapy (IMFP). The researcher believes the ethical application of IMFP will empower and inspire music therapy clinicians to expand their services to meet the mental health treatment needs of this emergent group of consumers.

Doctor of Philosophy, University of Akron, 2022, Electrical Engineering

This research proposes a direct voltage control approach for electric motors, including the single-stage converter topology and the control algorithms. The proposed motor drive system achieves smooth output voltage waveforms for phase excitations and utilizes them to extend the drive capability besides improving the torque ripple, noise, and vibration performance. Applicable to various motor types, the direct voltage control (DVC) is mainly investigated for driving switched reluctance motor (SRM) in the scope of this thesis. Different voltage regulation-based control algorithms are studied. Since the capability of shaping the phase voltage precisely allows control of any motor variables, this ability enables regulating the phase currents, flux linkages, and phase voltages to obtain superior performance. A finite element analysis (FEA) is performed to characterize the motor for building a dynamic simulation model for an SRM. The developed DVC and the conventional control are simulated using this machine model in comparison to each other. A new dual polarity power converter (DPC) is modeled, which can buck and boost the DC bus voltage and provides a variable voltage generation (VVG). The DPC can process power in both directions and provide a variable voltage in both positive and negative polarities at the motor windings. Following the DPC design process, power boards and gate driver boards are manufactured and populated as modular systems for individual motor phases. The developed converter model is customized and sized to construct a motor drive for the targeted operating conditions of the investigated SRM. It includes a control board to enable the 3-phase operation and a single DC bus as the power source for all three modular power converters. A resistive load setup is built to test the converter's performance. After verifying the DPC's performance for its designed load conditions and position-dependent dynamics, the motor tests are performed. The motor tests (open full item for complete abstract)

Doctor of Philosophy, University of Akron, 2022, Polymer Science

Photoelectrochemical (PEC) conversion of biomass (e.g., lignin) to hydrogen, a carbon-negative emission technology, is characterized by four key processes: (i) photo-generated electron-hole pairs, (ii) electron transport from the anode to the cathode, (iii) hydrogen generation at the cathode and (iv) biomass oxidation by photogenerated holes in the valence band. Overall performance of the photoelectrochemical cell is governed by step (i), electron-hole generation, followed by step (iv), charge transfer at the semiconductor/electrolyte interface. This dissertation will discuss the development of an in situ infrared spectroscopic (IR) approach to study charge dynamics during PEC reactions. Accumulated photogenerated electrons on the semiconductor surface in PEC reactions exhibit a structureless, and featureless spectrum centered around 2000 cm-1. The intensity and rate of the IR profile of photogenerated electrons at this wavenumber correlates to the charge transport in the PEC process, qualitatively characterizing the efficiency of the catalyst. Electron accumulation can also be observed under dark conditions with negative voltage bias. Adsorbed water on the semiconductor surface serves as a hole scavenger and shields the catalyst surface from oxygen, preventing electron-hole recombination, while simultaneously promoting the formation of a double layer of electrons and protons on the semiconductor surface. The effect of voltage on the performance of the PEC cell is investigated through the analysis of the IR profile (i.e., relative concentration) of photogenerated electrons. The results of charge dynamics shed a light on the PEC mechanism and provide a scientific basis for devising novel approaches to enhance the PEC efficiency. The observations of the dynamics of accumulated electrons and water coverage in PEC reactions revealed the applicability of the in situ IR approach to electro-swing CO2 capture in liquid monoethanolamine (MEA). CO2 reacts with amines (open full item for complete abstract)

Master of Sciences (Engineering), Case Western Reserve University, 2021, Macromolecular Science and Engineering

Herein, a comprehensive method for the electrochemical characterization of carbonaceous catalysts for Carbon Dioxide Reduction is presented. A standard air-tight H-cell set-up, with custom made Teflon lids, a 3D printed TPU electrolyte displacement insert, a pH probe, and a gas line capable of bubbling both N2 and CO2 at controlled flow rates is assembled. A multitude of techniques for catalyst coating of working electrodes are shown. Many of these electrodes were then used for electrochemical techniques such as linear sweep voltammetry and set potential electrolysis. Electrochemical methods for electrochemical surface area determinations, double layer capacitance measurements, and electrochemical impedance spectroscopy have been employed. Additionally, a detailed explanation of methods for resistance compensation is provided. Developed gas collection techniques are expected to be effective, with gaseous product detection remaining a challenge. Detection and quantification of liquid products via. a unique GC- MS method and two different NMR methods have been successfully developed, with calibration curves made for various potential liquid products. It is the goal that the methods developed here will enable the straightforward characterization of novel nitrogen-doped carbonaceous catalysts for the Carbon Dioxide Reduction Reaction, in order to better understand the structure-activity relationships of carbon-based electrocatalysts.

Master of Science in Electrical Engineering, Cleveland State University, 2021, Washkewicz College of Engineering

With increasing load and aging grid infrastructure, an accurate study of power flow is very important for operation and planning studies. The study involves a numerical calculation of unknown parameters, such as voltage magnitude, angle, net complex power injection at buses and power flow on branches. The performance of traditional iterative power flow methods, such as Newton-Raphson, depends on initial starting point, does not guarantee solution for heavily loaded, and poor convergence for unbalanced radial power system. Holomorphic load embedding is a non-iterative and deterministic method for finding steady-state solutions of any power system network. The method involves converting voltage parameter at every bus into an embedded parameter (\alpha) where analytic continuation is applied using Pade` approximants. The embedded parameter (\alpha) acts as a well-defined reference for the complex analysis and solution obtained when setting a simple value \alpha is known as Germ Solution, by some texts. Using the values of coefficient of Maclaurin Series, the Holomorphic method can find solutions in the whole complex plane using analytic continuation as it extends the nature of function beyond the radius of convergence. The holomorphic embedding method has been applied in the past to solve power flow problems in balanced power system models. There are several advantages of the said method over traditional iterative techniques, such as guaranteed convergence, the existence of solution, and faster calculation for certain cases. The method dives into complex analysis, algebraic curves, Taylor series expansion, Pade` approximants, and solving a linear set of equations. For simplicity purpose, the networks are often assumed to be balanced with constant power loads. Power flow analysis and its derivatives are performed on a single-phase equivalent of the same system. For bulk systems, the assumption is acceptable as load aggregation balances the loads in each phase t (open full item for complete abstract)