Master of Science, University of Akron, 2017, Polymer Science

Inspired by Nature, scientists have constructed numerous sophisticated supramolecular architectures based on various non-covalent interactions, among which metal-ligand coordination has played an important role, as a powerful and principle tool. The terpyridine-metal-terpyridine (tpy-M2+-tpy) linkage has been used widely, because [2,2':6',2"]-terpyridine (tpy) is able to coordinate with various metal ions to form desired discrete macromolecules. A bimetallic triangle was synthesized using a hydrophilic mono-Ru2+-dimeric ligand and a hydrophobic bis-terpyridine ligand, which has a central benzene ring possessing 60° angle between two attached terpyridines for the construction of triangular structures. The aggregation of this amphiphilic triangular complex in solution was studied using TEM and the vesicles with diameter of about 80 nm were clearly observed. Synthesis of two first-generation Sierpinski triangles using tailored "V" shaped bis- and "K" shaped tetrakis-terpyridine ligands has been described. The one-step assembly was achieved by an exact 1:1 molar ratio of two ligands coupled with three equivalents of Cd2+ ions. The 1H NMR, ESI- and TWIM-MS data clearly confirmed their structures. Another triangular complex was achieved using the specific bis-terpyridine possessing a 24-crown-8 moiety, which was treated with Zn2+ ions in a precise 1:1 molar ratio to give the desired complex. Then it was treated with organic ammonium cations for the investigation of their host-guest interaction. The stacked 1H NMR spectra suggest that the ammonium cation was anchored within the cavity of crown ether and subsequently changed the conformation of complex. The artificial polyhedral complexes were designed based on geometric principles to mimic the highly symmetric cage-like structures. A cuboctahedron-shaped complex was quantitatively obtained by the treatment of Ru2+-dimer of "X" shaped tetrakis-terpyridine ligands and Zn2+ ions in 1:3 molar ratio. The 1H NMR, ESI (open full item for complete abstract)

Committee: George R. Newkome (Advisor); Yu Zhu (Committee Member) Subjects: Chemistry

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

Wire electrical discharge machining (WEDM) enables production of complex parts with tight tolerances, although maintaining dimensional accuracy in corners and tapers remains challenging due to wire deflection and vibration. This study optimizes WEDM parameters for achieving high-accuracy in machining complex geometrical parts and taper cuts in 6061 Aluminum alloy using Excetek W350G WEDM machine with a copper wire electrode. Parameters including Wire Tension, Pulse On-Time, Pulse Off-Time, Wire Feed Rate, Open Circuit Voltage, and Flashing Pressure were varied using L18 Taguchi Orthogonal Array and response graph method to identify optimal cutting conditions. Results indicated feature-specific optimization is crucial, as different geometrical features (rectangular fins, triangular fins, gears) exhibited varying critical parameters. Key findings highlighted the importance of Wire Tension and Pulse On-Time in maintaining cutting accuracy, although at varying levels for specific features. Response graphs demonstrated effects of major WEDM parameters on corner and profile accuracies, whereas Taguchi analysis provided optimum settings of parameters for each feature and taper cutting. Validation experiments for rectangular fins showed significant improvement in the dimensional error for the fin length and taper angle. These advancements will enhance precision, efficiency, and versatility of WEDM processes in machining complex profiles, and corners, contributing to precision manufacturing.

Committee: Muhammad Jahan (Advisor); Carter Hamilton (Committee Member); Jinjuan She (Committee Member) Subjects: Aerospace Engineering; Biomedical Engineering; Industrial Engineering; Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2020, History

I argue that the relationship among Great Britain, Japan, and the United States between 1900 and 1920 resembles an informal triumvirate that maintained geo-strategic stability around the Pacific Rim. Those countries' foreign policymakers routinely considered how their actions would impact the others and affect the geo-strategic balance in East Asia. Great Britain often proved the counterweight to balance tensions between the United States and Japan – two rising powers with sometimes conflicting goals in the region. When potential conflicts arose, those nations' leaders favored diplomatic means of resolving the tensions. The triumvirate began to coalesce during the late 1890s as crises erupted in China. After the Boxer War, Great Britain and Japan entered into a formal alliance with one another, while the United States pressed for an Open Door policy in China. Despite differing interpretations of the Open Door Policy, the three countries' leaders all agreed on its importance. With shared interests in mind, American and British leaders supported Japan's war against Russia. Afterwards, Great Britain and Japan re-affirmed their alliance, and American and British leaders sought more amiable relations as tensions between them in the Western Hemisphere abated. The triumvirate experienced its first major crisis in 1906-1907 when Japan and the United States butted heads over immigration, resulting in a war scare. Although they averted conflict, Great Britain's increasing focus on Europe jeopardized the fragile balance in Asia. With fewer Pacific competitors, Japanese political coalitions pulled their state's foreign policy in different directions, resulting in increased tensions among the three powers. Various political leaders, though, aimed to settle that turbulence, and during and after World War I the three nations sought a new Pacific power-balance. Eventually, they formalized their relationship through the three treaties enacted by Washington Naval Conference of 1921 (open full item for complete abstract)

Committee: Peter Mansoor (Advisor); Philip Brown (Committee Co-Chair); Jennifer Siegel (Committee Member) Subjects: History

MS, Kent State University, 2016, College of Arts and Sciences / Department of Mathematical Sciences

Let R be a ring. A map f over R is said to be commuting if each x in R commutes with its image under f. In this thesis, we provide a brief examination of the development of the theory of commuting maps. We then provide a characterization of all linear commuting maps over the nilpotent algebra of strictly upper triangular matrices with elements in a field of characteristic zero.

Committee: Mikhail Chebotar Dr. (Advisor); Artem Zvavitch Dr. (Committee Member); Jenya Soprunova Dr. (Committee Member) Subjects: Mathematics

Doctor of Education, Ashland University, 2013, College of Education

This study explored a triangular relationship among teachers, students, and administrators at an English as Second Language (ESL) learning center in a mid-sized, private, non-profit university in the Midwest in the United States. Through the use of critical theory, this study simultaneously gave the three groups of stakeholders voices, interwove their comments, and emerged a system thinking: a whole picture of an ESL learning center. The result from this study revealed administrators' pressure, five teachers' frustration, and nine students' learning agonies. In terms of the findings, this study grounded a leadership theory of an ESL learning center management.

Committee: James Olive PhD (Committee Chair); Harold Wilson PhD (Committee Co-Chair); James Rycik PhD (Committee Member); Carla Abreu-Ellis PhD (Committee Member) Subjects: English As A Second Language; Higher Education

PhD, University of Cincinnati, 2004, Engineering : Mechanical Engineering

The dissertation is to address the need, in contact mechanics, of efficient and effective solutions to certain 3-D contact problems. The solutions developed here are based on underlying analytical solutions to pyramidal loading elements. This feature, along with other characteristics, distinguishes this method from other numerical solutions. The research work is logically divided into three subsequent parts, each of which addresses a particular aspect of the project: (1) Developed analytical solution sets in closed form to pyramidal loading profiles. First, a set of Boussinesq-Curruti equations to linear/bilinear distribution of normal and tangential loading over a triangular area are derived and evaluated. Second, solution sets to normal and tangential surface loading pyramids are constructed. The work provides a solution set to a basic loading element, which is the foundation of the development of effective and efficient semi-analytical solutions to 3-D contact problems with general geometry and loading profile. (2) Developed a semi-analytical approach (non-incremental algorithm) to 3-D normal contact problems with friction. This approach treats normal contact (indentation) phenomenon as a static problem. Based on fully coupled governing equations, the algorithm of contact detecting and stick/slip partitioning is designed as nested iterations, to fulfill contact boundary conditions. The computation shows that it is an efficient algorithm. Numerical examples are presented to show the accuracy and efficiency of the method.(3) Developed a semi-analytical approach (incremental algorithm) to 3-D contact problems with friction. This approach treats contact as a dynamic problem. The general dynamic models are simplified into quasi-static models in many practical cases that inertial force can be ignored. The incremental algorithm is designed to solve the quasi-static problems. The computation shows that the algorithm works very well for cases featuring both similar and di (open full item for complete abstract)

Committee: Dr. EDWARD BERGER (Advisor) Subjects: Engineering, Mechanical

Doctor of Philosophy, The Ohio State University, 2009, Civil Engineering

A survey of experts that work in the protection of critical infrastructure was developed and administered that captured the data upon which the analysis rests. The survey consisted of four major sections: consent, primary data acquisition, demographic data acquisition, and closing remarks. Primary data acquisition focused on four areas: weapon implementation likelihood and a three variable: consequence, threat, and vulnerability; risk function. There were two scales used in the primary data acquisition a forced rank order and a 7-point Likert scale.Non-parametric and parametric statistical models were used to analyze the data, describe the behavior, establish relationships, and explain the phenomena. The non-parametric model, Friedman's test, was used to ascertain a rank order based on the data from weapon implementation likelihood in the four major weapon categories: conventional, chemical biological and nuclear. The parametric model consisted of the proportional odds model which was used to explore the relationships through the risk function. The proportional odds model calculated cumulative and individual probabilities of a response level, and point estimates of severity. Confidence intervals were projected using the bootstrap method and the models were validated using internal cross validation procedures. The proportional odds model estimates consequence, threat, and vulnerability values. These values can be used separately in risk management and analysis or manipulated using other methodologies. A fuzzy logic triangle model was used to estimate risk from the consequence, threat, and vulnerability values. The model represents a reasonable estimate of risk. Critical infrastructure protection is crucial to the functioning of US society, the economy, democracy, and national security. The terrorist attacks on the World Trade Center caused a shift in strategic, operational, and tactical policy toward improving critical infrastructure protection by the public and priv (open full item for complete abstract)

Committee: Fabian Tab PhD (Advisor); William Wolfe PhD (Committee Member); Christopher Holloman PhD (Committee Member) Subjects: Civil Engineering

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

Delays in construction projects are inevitable; as a result claims and disputes arise among different construction parties. Different causes of delay can come into play, therefore, there is a need to identify and classify different causes of project delay. Estimation of the likelihood of delay resulting from different factors that contribute to project delay is essential to project success. Different factors that contribute to project delay affect the likelihood of project delay in different effectiveness degrees. There is a pressing need to estimate the likelihood of delay by implementing analysis methods and examining these methods. Probabilistic fault tree analysis and fuzzy fault tree analysis are two methods suggested by this research to estimate the likelihood of delay. Fuzzy fault tree analysis is performed by planners and managers since they select the delay causes that are applicable to a given project and categorize these delay causes into enabling, triggering, and procedural causes. Then, managers assess the degree of effectiveness of each cause of delay to overall project delay. Assessment of the contributing causes of delay and their degree of effectiveness on project delay uses subjective judgment linguistic terms. The result of the fuzzy fault tree analysis is a likelihood of delay membership function that is compared to the predefined fuzzy logic model to assess the degree of severity of the likelihood of delay. Likelihood of delay membership function is further quantified using the weighted average defuzzification method. Different fuzzy logic models are implemented into the fuzzy fault tree analysis, using Visual Basic software, these models are Baldwin's rotational model, the Angular model, the Translational model and the Triangular model. Recommendation of the fuzzy logic model that is best applied to a given scenario needs further sensitivity analysis and is beyond the scope of this research. Validation of the fuzzy fault tree analysis computer (open full item for complete abstract)

Committee: Fabian Tan (Advisor) Subjects: Engineering, Civil

Master of Science (MS), Ohio University, 2010, Physics and Astronomy (Arts and Sciences)

Structural glasses exhibit the phenomenon of dynamical heterogeneity: different regions of the system present different dynamical behavior. To study this phenomenon, we compute the triangular relations of the local and global two-time correlation functions, C(r;t,tw) and C(t,tw), from simulations of four models of structural glasses performed in the aging regime. The triangular relations are the mathematical relationships among correlators calculated for the time pairs (t1, t2), (t2, t3) and (t1, t3) with t1 > t2 > t3. We build the 2D joint probability density of the local correlation functions C(r;t1,t2), C(r;t2,t3) and C(r;t1,t3) and plot the triangular relations of the global and local correlations together to compare their behavior. We find that the probability distribution of local correlations is concentrated along the curve representing the global correlations. The results are very similar in all of the four systems considered. Our results provide evidence of time reparametrization invariance and also point toward universality in the aging fluctuations.

Committee: Horacio Castillo Dr. (Advisor); Martin Kordesch Prof (Committee Chair); Maddapa Prakash Prof (Committee Member) Subjects: Physics

MS, Kent State University, 2009, College of Arts and Sciences / Department of Computer Science

There is still much research in the areas of routing and location updates in cellular communication networks. Given the limited amount of memory and power of these network devices it is desirable to find the most effective and resource conscious method for solving routing and location update problems. Recently, these problems have been addressed for simply connected cellular networks and significant results were achieved.  An effective method for addressing, location update and routing has been offered using a method of isometric embeddings into a set of three trees.  This method however does not fully work when a hole is present in the network.  To handle networks containing holes, a variation of the above method is required, where the cellular network will be decomposed into few sub-graphs that encompass the properties of the original network graph.  Proposed here is a method that will handle the above mentioned problems on cellular networks with holes, namely holes with disc structures and other shapes that have the convex property.  Also presented are two distinct methods for handling networks with multiple disc-structured holes.  These methods will also use sub-graphs to reduce the number of holes while preserving all shortest paths.

Committee: Feodor F. Dragan PhD (Advisor); Ruoming Jin PhD (Committee Member); Hassan Peyravi PhD (Committee Member) Subjects: Computer Science