Master of Science (M.S.), University of Dayton, 2023, Renewable and Clean Energy

Bifacial solar photovoltaic modules generate electrical power on both sides of the panel, increasing energy output. Through more effective utilization of installed surface area, bifacial panels surpass the energy generation of monofacial panels per unit installed acreage. The performance of bifacial panels largely depends on their positioning relative to the sun. Therefore, bifacial panels require specific orientations to maximize energy production. The specific challenges of bifacial modules have sparked research into the ideal spacing and orientation of bifacial panels, considering geographic location, tilt angles, and solar energy production. The present study aims to pinpoint the most favorable tilt angles, azimuth angles, and panel row spacings for bifacial panels across various latitudes for a fixed array area and an adjustable array area. The core objective of this research is to maximize the electricity generated by bifacial solar panels. This involves creating a model that predicts power output for a specific location, accounting for variables like panel spacing, azimuth angle, average cell temperature, local ground reflection, and panel efficiency. The study also seeks to employ optimization to achieve peak annual power production. Methodologically, the study stratifies the solar panel array into zones, calculating the power generation capacity for a central panel in each zone. This includes factors like cell temperature, efficiency, and irradiance levels on both sides. Such calculations leverage Python APIs and packages for efficiency and accuracy. The computational model also factors in shadow effects, albedo, panel placement, and atmospheric conditions. To determine the optimal setup, the study adjusts variables such as panel tilt, azimuth angle, and spacing between panels using a differential evolution algorithm. The results reveal that optimal power production exists for bifacial panels with an associated optimal tilt angle, azimuth angle, and panel s (open full item for complete abstract)

Committee: Rydge Mulford (Committee Chair); Andrew Chiasson (Committee Member); Kevin Hallinan (Committee Member) Subjects: Energy; Engineering; Sustainability

Master of Science, The Ohio State University, 2022, Agricultural and Extension Education

To address the phenomena of social media marketing of show livestock in Ohio, researchers must understand the elements of social media marketing materials being produced by show livestock producers. This provides researchers with the ability to inform future research of social media marketing within agriculture. Upon examination, it was determined that producers rely heavily on photographs, videos, and graphics (advertisements, flyers, catalogs, etc.). Accordingly, four elements of photography, four elements of videography, and three elements of graphic design were chosen by researchers gain a better understanding of the quality of materials being produced by show livestock producers. This study integrated the use of the Importance-Performance Analysis model to assess the quality of the materials being produced, and the importance the producers put on their elements. The strategies that were identified for this research are the following: the elements investigated for the use of photographs or videos in the posts were (1) exposure (lighting), (2) angle, (3) rule of thirds, (4) quality. If a graphic is included in social media post, the attributes being investigated are (1) type, (2) color, and (3) arrangement. Findings from this study showed that while performance of following the rule of thirds and professional appearance of photographs was high, it was not something that was particularly important to them. Conversely, importance of professionally appearing videos was of high importance, but none of the participants had videos that appeared to be professionally produced. Following the rule of thirds in videos fell into low importance and low performance. Thus, rule of thirds in video may not be an area that producers should focus on at this time. All the other elements of videography and photography fell into the keep up the good work quadrant for the importance-performance analysis. Lastly, all the elements of graphic design fell into the keep up the good work (open full item for complete abstract)

Committee: Emily Buck (Advisor); Joy Rumble (Committee Member) Subjects: Agricultural Education; Agriculture; Animal Sciences; Animals; Communication; Curriculum Development; Education; Journalism; Marketing; Mass Communications; Web Studies

Doctor of Philosophy, The Ohio State University, 1955, Graduate School

Committee: Not Provided (Other) Subjects: Psychology

Master of Science (MS), Bowling Green State University, 2016, Physics

Using the Plexiglas Model M5, a static hemilarynx condition was produced using vocal fold pieces housed within a wind tunnel to collect pressure distributions throughout the glottis under constant flow conditions. In order to make the hemilarynx condition, one vocal fold piece was always kept vertical within the glottis, while the other spanned three different glottal angles, one converging, one uniform, and one diverging. The variability of glottal diameter was also introduced and data was collected at 0.01, 0.04, and 0.16 cm diameters. Pressure distributions and flow rates for such configurations are of interest for the analysis of phonation in patients for whom one vocal fold has been immobilized. Flow bistability was introduced at each of the glottal diameters for each glottal angle. Observations regarding the effect that flow bistability had on the pressure distributions showed that a bistable condition of flow produced noticeably less prominent changes in the pressure values intraglottally than the changes in pressures related to the asymmetric angles themselves. The flow bistability therefore created the greatest differences in larger diameter cases. From these pressure distributions, the data can be used in other multimass models to provide insight into the asymmetric forces that may occur within the larynx during phonation.

Committee: Lewis Fulcher Dr. (Advisor); Marco Nardone Dr. (Committee Member); Ronald Scherer Dr. (Committee Member) Subjects: Biophysics; Physics; Speech Therapy

Master of Science in Mechanical Engineering, Cleveland State University, 2015, Washkewicz College of Engineering

A newly developed production test stand for measuring the spray angle of a pressure swirl atomizer was constructed and used to measure a product line of these pressure swirl atomizers – the macrospray atomizer. This new test stand, utilizing constant temperature hot wire anemometers, captures the spray angle data based on the voltage drop the hot wire probes see as they traverse the spray cone of the atomizer and as fluid droplets impinge upon the wire. Datasets acquired from the experiments are compared and correlated with computational fluid dynamics (CFD) simulation data. In addition, angles obtained from another type of spray characterization technique, the spray angle device, are also compared to see how closely CFD can predict the angle as captured by this new stand and how reliable and independent of human error it is. Another nozzle with a pressure swirl atomizer, the conventional atomizer, is also simulated to compare its agreement with experimental values obtained from the spray angle device. Finally, the datasets are compared to understand if the CFD results, when compared to the two spray characterization techniques used in this thesis for both the nozzle and atomizer can be utilized to assist in future atomizer designs. For the macrospray atomizer, it was found through the experiments that the hot wire stand predicts the spray angle more accurately within 10% error. The spray angle device measured the spray angles within an error of 29% while the CFD introduced more error into the spray angle measurement obtained, within 7% to 93%. The conventional atomizer was found to have an error up to 18% with CFD results and up to 28% with the manual spray angle device.

Committee: Mounir Ibrahim Ph.D. (Committee Chair); Vikram Shyam Ph.D. (Committee Member); Ralph Volino Ph.D. (Committee Member) Subjects: Engineering; Fluid Dynamics; Mechanical Engineering

MS, University of Cincinnati, 2009, Engineering : Materials Science

Peel ply treatment, sanding, grit-blasting, and plasma etching were used to prepare the surface of graphite/epoxy composites in order to improve surface adhesion performance. We measured the contact angles on the treated surfaces and subsequent wetting anisotropy was found on the sanded and grit blasted surfaces. Linear Kaelble method was employed to determine the surface energy. It was found that polar component of surface energy of sanded and girt blasted composites was between 0 mJ/m2 to 1.4 mJ/m2 while dispersive component of surface energy was between 41.0 mJ/m2 to 56.6 mJ/m2. The surface energy of composites after plasma etching with gap being 1.90 cm was 67.6 mJ/m2 with polar component of surface energy being 36.7 mJ/m2 and dispersive component of surface energy being 30.9 mJ/m2 while the surface energy of composites after plasma etching with gap being 2.54 cm was 41.4 mJ/m2 with polar component of surface energy being 3.0 mJ/m2 and dispersive component of surface energy being 38.4 mJ/m2. The surface energy results indicated the increase of the surface energy of sanded and grit-blasted composites was mainly due to the increase of the dispersive component of the surface energy while the increase of the surface energy after plasma etching treatment was attributed to the increase of the polar component of the surface energy. Moreover, the effect of plasma etching on the surface energy of composites was greatly influenced by plasma etching gap distance.XPS results indicated that sanding and grit blasting did not cause significant surface chemical composition changes compared with surface chemical composition of peel ply treated surfaces. After plasma etching with gap being 2.54 cm, there was a slight increase of oxygen concentration and decrease of carbon concentration while plasma etching with gap being 1.90 cm greatly changed the surface composition by increasing oxygen concentration and decreasing carbon concentration. Therefore, low content of polar functiona (open full item for complete abstract)

Committee: F.James Boerio (Committee Chair); Rodney Roseman (Committee Member); Vesselin Shanov (Committee Member) Subjects: Engineering

MS, University of Cincinnati, 2008, Engineering : Civil Engineering

The following study attempts to find a suitable buckling restraining mechanism that could be easily attached to existing brace members in concentrically braced frame structures to enhance their lateral load resistance. Several sets of double angles representing half-scale braces from a model building were fabricated. Steel pipes were strapped to some of the brace specimens to enhance their buckling strength. The enhanced or retrofitted brace yielded a 36 percent increase in buckling capacity over a bare brace. The laboratory results were scaled to fit the model building, and a series of collapse analyses incorporating different bracing scenarios was conducted. Retrofitting the ground floor in the model building nearly doubled the base shear resistance at the onset of buckling, and a 17 percent increase in the ultimate lateral load. The inter-story drift of the model building remained well within serviceability limits when the ground level braces reached their buckling capacity. Retrofitting the ground level braces allowed the model building to be used in a wider area of the country.

Committee: Bahram Shahrooz Dr (Committee Chair); Gian Rassati Dr (Committee Member); James Swanson Dr (Committee Member) Subjects: Engineering

Master of Science, The Ohio State University, 2012, Mechanical Engineering

In this study, a formulation to define the three-dimensional geometry of worm gear drives having non-right angle shafts is developed. The geometry of the worm is determined by defining the geometry of the cutter and solving the corresponding equation of meshing between the worm and the cutter. The geometry of the worm gear is then defined by using a cutter which has the exact shape of the worm and solving the corresponding equation of meshing between the worm and the worm gear. Both right- and left-hand, single enveloping worm drives of ZK type with any number of worm threads are included in this formulation. With the tooth surface geometries defined, a commercial finite element gear analysis package with specific worm mesh generators is used to develop a deformable-body model of a non-right angle worm gear pair A parametric design sensitivity study is performed by using this deformable-body model to quantify the effects of basic geometric parameters including the shaft cross angle, lead angle, pressure angle, and addendum and dedendum coefficients on the maximum contact stress and mechanical efficiency of the gear pairs. In addition, variations to shaft center distance and cross angle are introduced to investigate their influence on gear pair performance.

Committee: Dr. Ahmet Kahraman PhD (Advisor); Dr. Donald Houser PhD (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2011, Mathematics

In late 1950's M.V. Volkenstein and other chemists suggested a discretized model of polymers called Rotational Isomeric State approximation model (RIS model), in which torsional angles at each step of polymer configuration take values from a fixed finite set of angles. This model was further studied by P. Flory and others. One of the natural questions is what happens with polymer when number of its bonds tends to infinity. Investigation related to this question was not completely done at the time, while some results found then were not quite rigorously proved and remained justified by intuitive or heuristic arguments. The reason for this is because some mathematical techniques and results were either not known at the time RIS model was developed, or were discovered not long before. The work presented in this thesis is continuation of study on the RIS model done by Volkenstein, Flory and others. We consider what happens with the RIS polymer when the number of its bonds tends to infinity, and show that, under suitable scaling, it converges to the Kratky-Porod model. We rigorously prove (already known) convergence of the sequence of torsional angles of the polymer, which forms an inhomogeneous Markov chain, to some homogeneous Markov chain. We also show that the rate of this convergence is geometric. To prove that the RIS model converges to the Kratky-Porod model, we use sequence of stochastic rotations whose limit satisfies linear Stratonovich stochastic equation. Driving process of this equation is antisymmetric Gaussian stochastic matrix, which rises from the sequence of torsional angles.

Committee: Peter March PhD (Advisor); Saleh Tanveer PhD (Committee Member); Yuan Lou PhD (Committee Member); Dorinda Gallant PhD (Committee Member) Subjects: Mathematics; Molecular Chemistry

Doctor of Philosophy, The Ohio State University, 2009, Statistics

Environmental datasets such as those from remote-sensing platforms and sensor networks are often spatial, temporal, and very large or even massive. Analyzing large spatial or spatio-temporal datasets can be challenging and dimension reduction is usually necessary. In this work, we exploit the Spatial Random Effects (SRE) model with a fixed number of known but not necessarily orthogonal (multi-resolutional) spatial basis functions. The SRE model allows a flexible family of nonstationary covariance functions and the fixed number of basis functions results in dimension reduction and thus efficient computation. We propose priors on the parameters of the SRE model in a fully Bayesian framework. These priors are based on the covariance matrix parameterized in terms of Givens angles and eigenvalues, and they recognize the multi-resolutional nature of the basis functions. We compare this Givens-angle prior to other methods in a simulation study, to show its advantages and apply it to a large remote-sensing spatial dataset. We also apply the SRE model with the Givens-angle prior in a Bayesian meta analysis, where outputs from six different regional climate outputs (RCMs) are combined to construct a consensus climate signal with “votes” from each RCM. Moreover, we extend the SRE model to the Spatio-Temporal Random Effects (STRE) model for massive spatio-temporal datasets. We explicitly model the measurement error, the non-dynamic fine-scale variation, the dynamic spatial variation, and the trend. The optimal spatio-temporal predictions are derived efficiently through the fixed-rank model and a rapid recursive updating procedure through the Kalman filter. Formulas for optimal smoothing, filtering, and forecasting are derived. The improvement of combining past and current data using the methodology called Fixed Rank Filtering (FRF) to predict the current hidden process of interest, is illustrated with a simulation experiment. The methodology is also applied to a large spatio-te (open full item for complete abstract)

Committee: Noel Cressie (Advisor); Radu Herbei (Committee Member); Thomas J. Santner (Committee Member); Tao Shi (Committee Member) Subjects: Statistics

Doctor of Philosophy, The Ohio State University, 2007, Electrical Engineering

Distributed sensor networks are growing in popularity for a large number of sensing applications ranging from environmental monitoring to military target classification and tracking. However, knowledge of the individual sensor positions is a prerequisite to obtaining meaningful information from measurements made by the sensors. With the scale of sensor networks rapidly increasing due to advances in communications and MEMS technology, an automatic localization service based on inter-sensor measurements is becoming an essential element in modern networks. This dissertation studies fundamental aspects of localization performance while deriving general results for singular estimation problems. Because inter-sensor measurements, such as distances or angles-of-arrival (AOA), are invariant to absolute positioning of the sensor scene, localizing sensors with an absolute reference, e.g., latitude and longitude, is inherently a singular estimation problem suffering from non-identifiability of the absolute location parameters. This results in a corresponding singular Fisher information matrix. We consider means of regularizing the absolute localization problem and devise novel performance characterizations by showing that the location parameters have a natural decomposition into relative configuration and centroid transformation components based on the singularity of the problem. A linear representation of the transformation manifold, which includes representations of rotation, translation, and scaling, is used for decomposition of general localization error covariance matrices. The unified statistical framework presented – which naturally generalizes to non-localization problems – allows us to quantify and bound performance in the relative and transformation domains. These tools facilitate analysis of relative-only algorithms while enabling new algorithm development to finely tune performance in each subdomain. The analysis is applied to a novel closed-form AOA-based localiza (open full item for complete abstract)

Committee: Randolph Moses (Advisor) Subjects:

Master of Science, The Ohio State University, 1986, Industrial and Systems Engineering

Committee: William Marras (Advisor) Subjects:

Master of Arts (MA), Bowling Green State University, 2005, Psychology/Experimental

The human perceptual system demonstrates poorer performance when discriminating between two oblique angles, rather than when horizontal or vertical angles are involved, even if angular distance is constant. Previous research does not provide a clear picture though on the cause of this. Experiments have been conducted with results that suggest a form of Categorical Perception is occurring during angle discrimination, while other experiments have found results that do not suggest a form of Categorical Perception is occurring during angle discrimination. This study was conducted to attempt to bridge the gap between previously conducted experiments. Our findings suggest that the angled stimuli we used result in a Non-Categorical Perception of angle discrimination. However, another study, using more “object like” stimuli will need to be conducted to better understand the perceptual processes occurring during angle discrimination tasks.

Committee: Dale Klopfer (Advisor) Subjects: Psychology, Experimental

Master of Science in Engineering, University of Akron, 2010, Electrical Engineering

The switched reluctance machine (SRM) is receiving renewed attention as a viable candidate for various adjustable speed and high torque applications such as in the automotive, traction and aerospace industries. The unique feature of a SRM is its relatively simple mechanical structure; the rotor does not carry any windings, commutators or permanent magnets. The maintenance free usage makes it a good choice over other DC or AC drives. The software modeling and hardware testing of SRM, for four-quadrant operation, and the development of an optimum commutation angle controller for low output current ripple, and efficient battery charging using the switched reluctance generator (SRG) is presented in this thesis. Two different SRM models are simulated for controller development. One of the models is the geometry based machine model by A. Radun, which is used to develop the operation logic for four-quadrant control of a three-phase 12/8 pole SRM. The second model is based on torque and flux data generated through finite element analysis using the software Flux2D for the three-phase 12/8 SRM. Simulation results obtained from the models were used to develop a control strategy to adapt the commutation angles in real-time for efficient battery charging with minimized current ripple. Two digital controllers namely, the turn-on angle controller for regulating the charging current and the turn-off angle controller for minimizing current ripple (adjusting algorithm) are developed to deliver the desired output power. The controller algorithm is implemented in a TI digital signal processor (DSP) for real-time controls. The SRM power and control hardware cards are integrated into a complete SRM drive system for experimental verification. The experimentally obtained commutation angles are compared with the data table generated from simulation results.

Committee: Sozer Yilmaz Dr. (Advisor); Husain Iqbal Dr. (Committee Co-Chair); Hartley Tom Dr. (Committee Member); Elbuluk Malik Dr. (Committee Member) Subjects: Electrical Engineering