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open access

An Accelerometer-based Gesture Recognition System for a Tactical Communications Application

Description: In modern society, computers are primarily interacted with via keyboards, touch screens, voice recognition, video analysis, and many others. For certain applications, these methods may be the most efficient interface. However, there are applications that we can conceive where a more natural interface could be convenient and connect humans and computers in a more intuitive and natural way. These applications are gesture recognition systems and range from the interpretation of sign language by a computer to virtual reality control. This Thesis proposes a gesture recognition system that primarily uses accelerometers to capture gestures from a tactical communications application. A segmentation algorithm is developed based on the accelerometer energy to segment these gestures from an input sequence. Using signal processing and machine learning techniques, the segments are reduced to mathematical features and classified with support vector machines. Experimental results show that the system achieves an overall gesture recognition accuracy of 98.9%. Additional methods, such as non-gesture recognition/suppression, are also proposed and tested.
Date: December 2015
Creator: Tidwell, Robert S., Jr.
Partner: UNT Libraries
open access

Acceptance Theories for Behavior in Conducting Research: Instructors in the Rajabhat University System, Thailand

Description: Responding to globalization and its effects on education and research development, the Thai government decided to push all public universities to become autonomous and establish a system of quality assurances. The establishment of quality assurances has had a large impact on many Thai instructors, especially in new public universities. Thai instructors are now forced to more focus on conducting research because the number of research publications is regarded as one of the main criteria for quality universities. The purpose of this study is to investigate the key factors, at the individual and university levels, which impact on the instructors' behavior in conducting research of the full-time instructors in the faculty of Management Science from the Rajabhat Universities in Thailand. The current study will help explain how and why the instructors accept or refuse to conduct research and provide insight into the salient factors motivating the instructors to produce more research by conducting HLM. Data were collected from 694 participants at 37 institutions via a questionnaire survey. The findings revealed that there was no difference among these 37 universities on behavior in conducting research. The key factors statistically influencing behavior in conducting research of the instructors were facilitating conditions, academic degree, social influence, and usefulness as well as ease of conducting research that the instructors perceived. This study gained 46% of effect size.
Date: December 2015
Creator: Laksaniyanon, Benchamat
Partner: UNT Libraries
open access

Accurate Energetics Across the Periodic Table Via Quantum Chemistry

Description: Greater understanding and accurate predictions of structural, thermochemical, and spectroscopic properties of chemical compounds is critical for the advancements of not only basic science, but also in applications needed for the growth and health of the U.S. economy. This dissertation includes new ab initio composite approaches to predict accurate energetics of lanthanide-containing compounds including relativistic effects, and optimization of parameters for semi-empirical methods for transition metals. Studies of properties and energetics of chemical compounds through various computational methods are also the focus of this research, including the C-O bond cleavage of dimethyl ether by transition metal ions, the study of thermochemical and structural properties of small silicon containing compounds with the Multi-Reference correlation consistent Composite Approach, the development of a composite method for heavy element systems, spectroscopic of compounds containing noble gases and metals (ArxZn and ArxAg+ where x = 1, 2), and the effects due to Basis Set Superposition Error (BSSE) on these van der Waals complexes.
Date: December 2015
Creator: Peterson, Charles Campbell
Partner: UNT Libraries
open access

Addressing Multicultural Issues in the Counselor Education Classroom: a Phenomenological Analysis

Description: Multicultural education in counselor education is a popular topic among counselor educators and scholars. To date, scholars have focused on understanding the experiences of counselor educators who teach dedicated multicultural courses. However, less attention has been given to other counselor educators who are required by ethical and training standards to address multicultural issues across the curriculum. The purpose of this study was to understand counselor educators’ experiences addressing multicultural issues in courses that do not have a specific multicultural or diversity focus. I used phenomenological methodology to explore the experiences of counselor educators who hold doctoral degrees in counseling or a related field, have taken a multicultural/diversity course in their graduate training, are full-time clinical or tenure-line faculty members in CACREP-accredited programs, and have never taught courses dedicated to multicultural or diversity issues. Twelve participants (six men and six women), ranging in age ranged from 31 to 65, participated in the study. Ten participants identified as White, one African-American, and one Hispanic. The research team identified eight themes: (1) reasons for avoidance, (2) constraints, (3) qualities and practices, (4) educator as a factor in student development, (5) infusion, (6) personal background, (7) awareness of biases and assumptions, and (8) counselor educator responsibility/gatekeeping. Findings from this study will add to the literature regarding infusion of multicultural issues across the curriculum. Additionally, the implications offered will serve as a resource for counselor educators as they experience unique personal and professional challenges when addressing multicultural issues in classrooms beyond the main multicultural or diversity course offered in counseling programs. Implications for this study may lead to development of more focused guidelines on how to increase the increase the comfort of counselor educators as they facilitate multicultural discussions and assist counselors-in-training in working toward cultural competence.
Date: December 2015
Creator: Wagner, Terra M.
Partner: UNT Libraries
open access

Anger, Forgiveness and Mindfulness: Correlates of Perceived Stress in an LGB Sample

Description: A sexual minority is someone who identifies as lesbian, gay or bisexual (LGB). According to the Minority Stress Model (Meyer, 2003), sexual minorities encounter significant levels of stress due to their minority group status, thus they are more likely to experience perceived stress. Our cross-sectional, correlational study aimed to explore the relationships between forgiveness, mindfulness and anger and how they are related to perceived stress in a convenience sample of ethnically diverse LGB adults. We hypothesized that: 1) anger is positively associated with perceived stress; 2) forgiveness is negatively associated with perceived stress; 3) mindfulness is negatively associated with perceived stress; and 4) anger, forgiveness and mindfulness account for a significant proportion of the variance in perceived stress. 5) The relationship between anger and perceived stress is moderated by forgiveness. 6) The relationship between anger and perceived stress is moderated by mindfulness. Among LGB adults, the extant literature does not address these four variables in conjunction and the relationships between anger, forgiveness, mindfulness and stress has yet to be explored. Various statistical analyses were conducted, including a hierarchical linear regression to test our model. We found that our overall model accounted for 36% of the total variance in perceived stress (F(5, 142) = 17.31, p <.01) with anger (β = .31, t = 3.55, p = .001) and forgiveness (β = -.21, t = -2.56, p < .05) as the significant predictors. Contrary to prediction, forgiveness and mindfulness did not moderate the relationship between anger and perceived stress in our LGB sample. Limitations, strengths, future research and implications are discussed.
Date: December 2015
Creator: Schumacher, Matthew Robert
Partner: UNT Libraries
open access

Anisotropic Nature of Radially Strained Metal Tubes

Description: Metal pipes are sometimes swaged by a metal cone to enlarge them, which increases the strain in the material. The amount of strain is important because it affects the burst and collapse strength. Burst strength is the amount of internal pressure that a pipe can withstand before failure, while collapse strength is the amount of external pressure that a pipe can withstand before failure. If the burst or collapse strengths are exceeded, the pipe may fracture, causing critical failure. Such an event could cost the owners and their customers millions of dollars in clean up, repair, and lost time, in addition to the potential environmental damage. Therefore, a reliable way of estimating the burst and collapse strength of strained pipe is desired and valuable. The sponsor currently rates strained pipes using the properties of raw steel, because those properties are easily measured (for example, yield strength). In the past, the engineers assumed that the metal would be work-hardened when swaged, so that yield strength would increase. However, swaging introduces anisotropic strain, which may decrease the yield strength. This study measured the yield strength of strained material in the transverse and axial direction and compared them to raw material, to determine the amount of anisotropy. This information will be used to more accurately determine burst and collapse ratings for strained pipes. More accurate ratings mean safer products, which will minimize risk for the sponsor’s customers. Since the strained metal has a higher yield strength than the raw material, using the raw yield strength to calculate burst and collapse ratings is a conservative method. The metal has even higher yield strength after strain aging, which indicates that the stresses are relieved. Even with the 12% anisotropy in the strained and 9% anisotropy in the strain aged specimens, the raw yield strengths are …
Date: December 2015
Creator: Strickland, Julie N.
Partner: UNT Libraries
open access

Áskell Másson’s Solos for Snare Drum: Maximizing Musical Expression Through Varying Compositional Techniques and Experimentation in Timbre

Description: This dissertation and accompanying lecture recital explores the musical elements present in Áskell Másson’s three solos for snare drum, PRÍM (1984), KÍM (2001) and B2B: Back to Basics (2010). Two of the primary challenges for the performer when playing solo literature on a non-pitch oriented instrument are identifying thematic structures and understanding how to interpret all innovative sound production techniques employed within the music. A thematic and compositional analysis, as well as an investigation into the experimentation of timbre found in Másson’s three pieces for solo snare drum will help to clarify the musical complexities that are present throughout.
Date: December 2015
Creator: O’Neal, John Micheal
Partner: UNT Libraries
open access

Assessment of Hot and Cool Executive Functioning Following Trauma Using the Traditional Stroop Task, Emotional Stroop Task, and a Novel Implicit Association Test

Description: Individuals who have experienced a traumatic event and develop Post-Traumatic Stress Disorder (PTSD) frequently show deficits in both primarily “cool” and “hot” cognitive executive functions (e.g., traditional & emotional Stroop tasks, respectively) that can be impacted by high affective salience. Given the dimensional nature of psychopathology, questions remain about individuals within the general population who have experienced trauma but do not meet full criteria for PTSD and yet may manifest problems in these areas, especially areas of hot and cool executive functioning (EF). Thus, the current project was designed to assess hot and cool EF in a relatively large sample of individuals from the general population who have experienced trauma and currently demonstrate sub-clinical levels of post-traumatic symptoms. The Stroop task, Emotional Stroop task, and a novel modified Implicit Association Test were utilized to assess EF across a spectrum of individuals with varying traumatic histories and level of post-traumatic symptoms. Results suggest that a greater frequency of trauma experiences was moderately associated with worse performance on both hot and cool executive functioning measures. Specifically, females within the sample evidenced a close relationship between traumatic experiences, post-trauma symptoms, and executive functioning. Clinical and theoretical implications are discussed.
Date: December 2015
Creator: Sullivan, Erin
Partner: UNT Libraries
open access

Biological Applications of a Strongly Luminescent Platinum (II) Complex in Reactive Oxygen Species Scavenging and Hypoxia Imaging in Caenorhabditis elegans

Description: Phosphorescent transition metal complexes make up an important group of compounds that continues to attract intense research owing to their intrinsic bioimaging applications that arise from bright emissions, relatively long excited state lifetimes, and large stokes shifts. Now for biomaging assay a model organism is required which must meet certain criteria for practical applications. The organism needs to be small, with a high turn-over of progeny (high fecundity), a short lifecycle, and low maintenance and assay costs. Our model organism C. elegans met all the criteria. The ideal phosphor has low toxicity in the model organism. In this work the strongly phosphorescent platinum (II) pyrophosphito-complex was tested for biological applications as a potential in vivo hypoxia sensor. The suitability of the phosphor was derived from its water solubility, bright phosphorescence at room temperature, and long excited state lifetime (~ 10 µs). The applications branched off to include testing of C. elegans survival when treated with the phosphor, which included lifespan and fecundity assays, toxicity assays including the determination of the LC50, and recovery after paraquat poisoning. Quenching experiments were performed using some well knows oxygen derivatives, and the quenching mechanisms were derived from Stern-Volmer plots. Reaction stoichiometries were derived from Job plots, while percent scavenging (or antioxidant) activities were determined graphically. The high photochemical reactivity of the complex was clearly manifested in these reactions.
Date: December 2015
Creator: Kinyanjui, Sophia Nduta
Partner: UNT Libraries
open access

Characterization of Ti-6Al-4V Produced Via Electron Beam Additive Manufacturing

Description: In recent years, additive manufacturing (AM) has become an increasingly promising method used for the production of structural metallic components. There are a number of reasons why AM methods are attractive, including the ability to produce complex geometries into a near-net shape and the rapid transition from design to production. Ti-6Al-4V is a titanium alloy frequently used in the aerospace industry which is receiving considerable attention as a good candidate for processing via electron beam additive manufacturing (EBAM). The Sciaky EBAM method combines a high-powered electron beam, weld-wire feedstock, and a large build chamber, enabling the production of large structural components. In order to gain wide acceptance of EBAM of Ti-6Al-4V as a viable manufacturing method, it is important to understand broadly the microstructural features that are present in large-scale depositions, including specifically: the morphology, distribution and texture of the phases present. To achieve such an understanding, stereological methods were used to populate a database quantifying key microstructural features in Ti-6Al-4V including volume fraction of phases, a lath width, colony scale factor, and volume fraction of basket weave type microstructure. Microstructural features unique to AM, such as elongated grains and banded structures, were also characterized. Hardness and tensile testing were conducted and the results were related to the microstructural morphology and sample orientation. Lastly, fractured surfaces and defects were investigated. The results of these activities provide insight into the process-structure-properties relationships found in EBAM processed Ti-6Al-4V.
Date: December 2015
Creator: Hayes, Brian J.
Partner: UNT Libraries
open access

Characterizing the Molecular Changes of Austrofundulus limnaeus As It Develops Towards and Enters Diapause II

Description: Austrofundulus limnaeus is a species of annual killifish which inhabits ephemeral ponds in South America. The species is able to survive seasonally desiccating ponds due to their ability to produce robust embryos. The embryos of this species are capable of entering a developmental arrest, termed diapause II, which precedes the onset of drought. While in this arrested state embryos exhibit the greatest tolerance to anoxia of any characterized vertebrate at 25ºC. Furthermore, when raised at 30ºC, embryos escape the entrance to diapause II and go on to develop directly. Currently, little is known about the molecular mechanisms which induce and maintain this developmentally arrested state. In this study I have developed methods to analyze changes in histone modifications in the context of diapause II. Histone modifications were chosen due to their extreme conservation and well characterized role as modulators of gene expression in other systems. Results utilizing adapted immunobased assays show significant changes in the global amount of H3S10P, H3K27me and H3K4me, as the embryos progress from early embryogenesis through the exit of diapause. Additionally, it is revealed that there exists a degree of phenotypic plasticity with regards to the entrance into diapause II which is modulated by the environment (severe hypoxia 0.1% O2). This work builds a foundation for future histone modification studies and contributes the development of several tools to the field. This study contributes to a greater molecular understanding of the cue(s) which influence the remarkable phenomenon of obligate developmental arrest in a vertebrate embryo.
Date: December 2015
Creator: Toni, Lee S.
Partner: UNT Libraries
open access

Comparative Analysis and Implementation of High Data Rate Wireless Sensor Network Simulation Frameworks

Description: This thesis focuses on developing a high data rate wireless sensor network framework that could be integrated with hardware prototypes to monitor structural health of buildings. In order to better understand the wireless sensor network architecture and its consideration in structural health monitoring, a detailed literature review on wireless sensor networks has been carried out. Through research, it was found that there are numerous simulation software packages available for wireless sensor network simulation. One suitable software was selected for modelling the framework. Research showed that Matlab/Simulink was the most suitable environment, and as a result, a wireless sensor network framework was designed in Matlab/Simulink. Further, the thesis illustrates modeling of a simple accelerometer sensor, such as those used in wireless sensor networks in Matlab/Simulink using a mathematical description. Finally, the framework operation is demonstrated with 10 nodes, and data integrity is analyzed with cyclic redundancy check and transmission error rate calculations.
Date: December 2015
Creator: Laguduva Rajaram, Madhupreetha
Partner: UNT Libraries
open access

Comparing Three Effect Sizes for Latent Class Analysis

Description: Traditional latent class analysis (LCA) considers entropy R2 as the only measure of effect size. However, entropy may not always be reliable, a low boundary is not agreed upon, and good separation is limited to values of greater than .80. As applications of LCA grow in popularity, it is imperative to use additional sources to quantify LCA classification accuracy. Greater classification accuracy helps to ensure that the profile of the latent classes reflect the profile of the true underlying subgroups. This Monte Carlo study compared the quantification of classification accuracy and confidence intervals of three effect sizes, entropy R2, I-index, and Cohen’s d. Study conditions included total sample size, number of dichotomous indicators, latent class membership probabilities (γ), conditional item-response probabilities (ρ), variance ratio, sample size ratio, and distribution types for a 2-class model. Overall, entropy R2 and I-index showed the best accuracy and standard error, along with the smallest confidence interval widths. Results showed that I-index only performed well for a few cases.
Date: December 2015
Creator: Granado, Elvalicia A.
Partner: UNT Libraries
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Competing Models of Hegemonic Masculinity in English Civil War Memoirs by Women

Description: This thesis examines the descriptions of Royalist and Parliamentarian masculinity in English Civil War memoirs by women through a close reading of three biographical memoirs written by Margaret Cavendish, duchess of Newcastle; Lady Ann Fanshawe; and Lucy Hutchinson. Descriptions of masculinity are evaluated through the lens of Raewyn Connell's theory of hegemonic masculinity to understand the impact two competing models of masculinity had on the social and political culture of the period. The prevailing Parliamentarian hegemonic masculinity in English Civil War memoirs is traced to its origins before the English Civil War to demonstrate how hegemonic masculinity changes over time. The thesis argues that these memoirs provide evidence of two competing models of Royalist and Parliamentarian masculinities during the Civil War that date back to changes in the Puritan meaning of the phrase “man of merit”, which influenced the development of a Parliamentarian model of masculinity.
Date: December 2015
Creator: Du Bon-Atmai, Evelyn
Partner: UNT Libraries
open access

Computational Modeling of Small Molecules

Description: Computational chemistry lies at the intersection of chemistry, physics, mathematics, and computer science, and can be used to explain the behavior of atoms and molecules, as well as to augment experiment. In this work, computational chemistry methods are used to predict structural and energetic properties of small molecules, i.e. molecules with less than 60 atoms. Different aspects of computational chemistry are examined in this work. The importance of examining the converged orbitals obtained in an electronic structure calculation is explained. The ability to more completely describe the orbital space through the extrapolation of energies obtained at increasing quality of basis set is investigated with the use of the Sapporo-nZP-2012 family of basis set. The correlation consistent Composite Approach (ccCA) is utilized to compute the enthalpies of formation of a set of molecules and the accuracy is compared with the target method, CCSD(T,FC1)/aug-cc-pCV∞Z-DK. Both methodologies are able to produce computed enthalpies of formation that are typically within 1 kcal mol-1 of reliable experiment. This demonstrates that ccCA can be used instead of much more computationally intensive methods (in terms of memory, processors, and time required for a calculation) with the expectation of similar accuracy yet at a reduced computational cost. The enthalpies of formation for systems containing s-block elements have been computed using the multireference variant of ccCA (MR-ccCA), which is designed specifically for systems that require an explicit treatment of nondynamical correlation. Density functional theory (DFT) has been used for the prediction of the structural properties of a set of lanthanide trihalide molecules as well as the reaction energetics for the rearrangement of diphosphine ligands around a triosmium cluster.
Date: December 2015
Creator: Weber, Rebecca J.
Partner: UNT Libraries
open access

Conquering the Natural Frontier: French Expansion to the Rhine River During the War of the First Coalition, 1792-1797

Description: After conquering Belgium and the Rhineland in 1794, the French Army of the Sambre and Meuse faced severe logistical, disciplinary, and morale problems that signaled the erosion of its capabilities. The army’s degeneration resulted from a revolution in French foreign policy designed to conquer the natural frontiers, a policy often falsely portrayed as a diplomatic tradition of the French monarchy. In fact, the natural frontiers policy – expansion to the Rhine, the Pyrenees, and the Alps – emerged only after the start of the War of the First Coalition in 1792. Moreover, the pursuit of natural frontiers caused more controversy than previously understood. No less a figure than Lazare Carnot – the Organizer of Victory – viewed French expansion to the Rhine as impractical and likely to perpetuate war. While the war of conquest provided the French state with the resources to survive, it entailed numerous unforeseen consequences. Most notably, the Revolutionary armies became isolated from the nation and displayed more loyalty to their commanders than to the civilian authorities. In 1797, the Sambre and Meuse Army became a political tool of General Lazare Hoche, who sought control over the Rhineland by supporting the creation of a Cisrhenan Republic. Ultimately, troops from Hoche’s army removed Carnot from the French Directory in the coup d’état of 18 fructidor, a crucial benchmark in the militarization of French politics two years before Napoleon Bonaparte’s seizure of power. Accordingly, the conquest of the Rhine frontier contributed to the erosion of democratic governance in Revolutionary France.
Date: December 2015
Creator: Hayworth, Jordan R.
Partner: UNT Libraries
open access

The Countess of Counter-revolution: Madame du Barry and the 1791 Theft of Her Jewelry

Description: Jeanne Bécu, an illegitimate child from the Vaucouleurs area in France, ascended the ranks of the Ancien régime to become the Countess du Barry and take her place as Royal Mistress of Louis XV. During her tenure as Royal Mistress, Jeanne amassed a jewel collection that rivaled all private collections. During the course of the French Revolution, more specifically the Reign of Terror, Jeanne was forced to hatch a plot to secure the remainder of her wealth as she lost a significant portion of her revenue on the night of 4 August 1789. To protect her wealth, Jeanne enlisted Nathaniel Parker Forth, a British spy, to help her plan a fake jewel theft at Louveciennes so that she could remove her economic capital from France while also reducing her total wealth and capital with the intent of reducing her tax payments. As a result of the theft, her jewelry was transported to London, where she would travel four times during the French Revolution on the pretext of recovering her jewelry. This thesis examines her actions while abroad during the Revolution and her culpability in the plot. While traveling to and from London, Jeanne was able to move information, money, and people out of France. Jeanne was arrested and charged with aiding the counter-revolution, for which the Revolutionary Tribunal sentenced her to death. Madame du Barry represented the extravagance and waste of Versailles and of Bourbon absolutism, and this symbolic representation of waste was what eventually inhibited Jeanne’s success.
Date: December 2015
Creator: Lewis, Erik Braeden
Partner: UNT Libraries
open access

Creating Community in Isolation: the History of Corpus Christi’s Molina Addition, 1954-1970

Description: “Creating Community in Isolation: The History of Corpus Christi’s Molina Addition, 1954-1970” examines the history of the Molina Addition in Corpus Christi, Nueces County, Texas, and its serving district, the West Oso Independent School District, from 1954 to 1970. Specifically, this essay begins with an analysis of the elite-driven campaign to annex the blighted Molina Addition in September and October 1954. The city intended to raze the neighborhood and develop middle-class homes in place of the newly annexed neighborhood. Following the annexation of the Molina Addition, African American and ethnic Mexican residents initiated protracted struggles to desegregate and integrate schools that served their area, the West Oso Independent School District, as detailed in the chapter, “The West Oso School Board Revolution.” The chapter examines the electoral “revolution” in which Anglo rural elites were unseated from their positions on the school board and replaced by African American and ethnic Mexican Molina Addition residents. The third chapter, “Building Mo-Town, Texas,” focuses on residents’ struggle to install indoor plumbing, eliminate pit privies, construct paved roads, and introduce War on Poverty grants to rehabilitate the neighborhood. This chapter also offers a glimpse into the social life of Molina youth during the 1960s.
Date: December 2015
Creator: Gurrola, Moisés A.
Partner: UNT Libraries
open access

Culturally Proficient Leadership: Teacher Perceptions of Elementary School Principals in Urban, Title I Schools

Description: This study examined elementary teachers’ perceptions of their principal’s level of cultural proficiency. Practices for Developing a Culturally Competent School Environment, a survey Camille Smith and adapted by Dr. Mack T. Hines, was completed from a sample size of 119 teachers. The survey contained 35 items, including six constructs: valuing diversity, assessing the culture, managing the dynamics of difference, institutionalizing cultural knowledge and resources, adapting to diversity and inclusiveness. Teachers rated their principal using a Likert scale which consisted of 1 = never uses, 2 = rarely uses, 3 = sometimes uses, 4 = frequently uses, and 5 = always uses. Teachers of various races, ages and years with their principal participated in this study. The study reveals that these variables do not make a statistically significant difference in the teachers’ perception of how proficient they are in valuing diversity, a assessing his/her own culture and institutionalizing cultural knowledge. This quantitative study reveals the variances of statistical significance of teacher demographics: age, gender, years served under current principal and accountability rating of the school. Cultural proficiency is important to the development and maintenance of the necessary relationships among students, teachers, principals and the school community.
Date: December 2015
Creator: Hendrix, Royond P.
Partner: UNT Libraries
open access

Decoding the Formation of a Retail Giant: the Evolving Geography of Costco’s Store Network

Description: Although Costco operates over 580 warehouse stores throughout North America, their location strategy remains relatively unexamined in the economic geography literature. A cursory examination of Costco’s network makes it clear that the firm chooses to locate primarily in the suburbs of major cities, where income levels are somewhat higher than the national average. However, what is not clear is the extent to which other demographic and geographic factors adequately account for Costco’s store locations, and what strategy underlies the geography of the firm’s warehouse stores, especially in relation to its distribution network. This research studies Costco in order to decode the location strategies that have guided the company’s North American and international expansions. The investigation attempts to identify key elements of Costco’s multinational retail network, including this network’s evolution over time. This paper seeks to benefit both retail business and public policymakers by highlighting elements of Costco’s location strategy that have contributed to the firm’s success.
Date: December 2015
Creator: Testa, Peter
Partner: UNT Libraries
open access

Deformation Micro-mechanisms of Simple and Complex Concentrated FCC Alloys

Description: The principal objective of this work was to elucidate the effect of microstructural features on the intrinsic dislocation mechanisms in two FCC alloys. First alloy Al0.1CoCrFeNi was from a new class of material known as complex concentrated alloys, particularly high entropy alloys (HEA). The second was a conventional Al-Mg-Sc alloy in ultrafine-grained (UFG) condition. In the case of HEA, the lattice possess significant lattice strain due to the atomic size variation and cohesive energy differences. Moreover, both the lattice friction stress and the Peierls barrier height are significantly larger than the conventional FCC metals and alloys. The experimental evidences, so far, provide a distinctive identity to the nature and motion of dislocations in FCC HEA as compared to the conventional FCC metals and alloys. Hence, the thermally activated dislocation mechanisms and kinetics in HEA has been studied in detail. To achieve the aim of examining the dislocation kinetics, transient tests, both strain rate jump tests and stress relaxation tests, were conducted. Anomalous behavior in dislocation kinetics was observed. Surprisingly, a large rate sensitivity of the flow stress and low activation volume of dislocations were observed, which are unparalleled as compared to conventional CG FCC metals and alloys. The observed trend has been explained in terms of the lattice distortion and dislocation energy framework. As opposed to the constant dislocation line energy and Peierls potential energy (amplitude, ΔE) in conventional metals and alloys, both line energy and Peierls potential undergo continuous variation in the case of HEA. These energy fluctuations have greatly affected the dislocation mobility and can be distinctly noted from the activation volume of dislocations. The proposed hypothesis was tested by varying the grain size and also the test temperature. Activation volume of dislocations was a strong function of temperature and increased with temperature. And the reduction in grain …
Date: December 2015
Creator: Komarasamy, Mageshwari
Partner: UNT Libraries
open access

Design, Synthesis, and Characterization of Aqueous Polymeric Hybrid Composites and Nanomaterials of Platinum(II) and Gold(I) Phosphorescent Complexes for Sensing and Biomedical Applications

Description: The two major topics studied in this dissertation are the gold(I) pyrazolate trimer {[Au(3-R,5-R’)Pz]3} complexes in aqueous chitosan polymer and phosphorescent polymeric nanoparticles based on platinum(II) based complex. The first topic is the synthesis, characterization and optical sensing application of gold(I) pyrazolate trimer complexes within aqueous chitosan polymer. A gold(I) pyrazolate trimer complex, {[Au(3-CH3,5-COOH)Pz]3}, shows high sensitivity and selectivity for silver ions in aqueous media, is discussed for optical sensing and solution-processed organic light emitting diodes (OLEDs) applications. Gold(I) pyrazolate trimer complexes are bright red emissive in polymeric solution and their emission color changes with respect to heavy metal ions, pH and dissolved carbon dioxide. These photophysical properties are very useful for designing the optical sensors. The phosphorescent polymeric nanoparticles are prepared with Pt-POP complex and polyacrylonitrile polymer. These particles show excellent photophysical properties and stable up to >3 years at room temperature. Such nanomaterials have potential applications in biomedical and polymeric OLEDs. The phosphorescent hybrid composites are also prepared with Pt-POP and biocompatible polymers, such as chitosan, poly-l-lysine, BSA, pnipam, and pdadmac. Photoluminescent enhancement of Pt-POP with such polymers is also involved in this study. These hybrid composites are promising materials for biomedical applications such as protein labeling and bioimaging.
Date: December 2015
Creator: Upadhyay, Prabhat Kumar
Partner: UNT Libraries
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Design, Synthesis and Study of Supramolecular Donor – Acceptor Systems Mimicking Natural Photosynthesis Processes

Description: This dissertation investigates the chemical ingenuity into the development of various photoactive supramolecular donor – acceptor systems to produce clean and carbon free energy for the next generation. The process is inspired by the principles learned from nature’s approach where the solar energy is converted into the chemical energy through the natural photosynthesis process. Owing to the importance and complexity of natural photosynthesis process, we have designed ideal donor-acceptor systems to investigate their light energy harvesting properties. This process involves two major steps: the first step is the absorption of light energy by antenna or donor systems to promote them to an excited electronic state. The second step involves, the transfer of excitation energy to the reaction center, which triggers an electron transfer process within the system. Based on this principle, the research is focused into the development of artificial photosynthesis systems to investigate dynamics of photo induced energy and electron transfer events. The derivatives of Porphyrins, Phthalocyanines, BODIPY, and SubPhthalocyanines etc have been widely used as the primary building blocks for designing photoactive and electroactive ensembles in this area because of their excellent and unique photophysical and photochemical properties. Meanwhile, the fullerene, mainly its readily available version C60 is typicaly used as an electron acceptor component because of its unique redox potential, symmetrical shape and low reorganization energy appropriate for improved charge separation behavior. The primary research motivation of the study is to achieve fast charge separation and slow charge recombination of the system by stabilizing the radical ion pairs which are formed from photo excitation, for maximum utility of solar energy. Besides Fullerene C60, this dissertation has also investigated the potential application of carbon nanomaterials (Carbon nanotubes and graphene) as primary building blocks for the study of the artificial photosynthesis process.
Date: December 2015
Creator: KC, Chandra Bikram
Partner: UNT Libraries
open access

Detection of Ulcerative Colitis Severity and Enhancement of Informative Frame Filtering Using Texture Analysis in Colonoscopy Videos

Description: There are several types of disorders that affect our colon’s ability to function properly such as colorectal cancer, ulcerative colitis, diverticulitis, irritable bowel syndrome and colonic polyps. Automatic detection of these diseases would inform the endoscopist of possible sub-optimal inspection during the colonoscopy procedure as well as save time during post-procedure evaluation. But existing systems only detects few of those disorders like colonic polyps. In this dissertation, we address the automatic detection of another important disorder called ulcerative colitis. We propose a novel texture feature extraction technique to detect the severity of ulcerative colitis in block, image, and video levels. We also enhance the current informative frame filtering methods by detecting water and bubble frames using our proposed technique. Our feature extraction algorithm based on accumulation of pixel value difference provides better accuracy at faster speed than the existing methods making it highly suitable for real-time systems. We also propose a hybrid approach in which our feature method is combined with existing feature method(s) to provide even better accuracy. We extend the block and image level detection method to video level severity score calculation and shot segmentation. Also, the proposed novel feature extraction method can detect water and bubble frames in colonoscopy videos with very high accuracy in significantly less processing time even when clustering is used to reduce the training size by 10 times.
Date: December 2015
Creator: Dahal, Ashok
Partner: UNT Libraries
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