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Dissimilar Joining of Al (AA2139) – Mg (WE43) Alloys Using Friction Stir Welding

Description: This research demonstrates the use of friction stir welding (FSW) to join dissimilar (Al-Mg) metal alloys. The main challenges in joining different, dissimilar metal alloys is the formation of brittle intermetallic compounds (IMCs) in the stir zone affecting mechanical properties of joint significantly. In this present study, FSW joining process is used to join aluminum alloy AA2139 and magnesium alloy WE43. The 9.5 mm thick plates of AA2139 and WE43 were friction stir butt welded. Different processing parameters were used to optimize processing parameters. Also, various weldings showed a crack at interface due to formation of IMCs caused by liquation during FSW. A good strength sound weld was obtained using processing parameter of 1200 rev/min rotational speed; 76.2 mm/min traverse speed; 1.5 degree tilt and 0.13 mm offsets towards aluminum. The crack faded away as the tool was offset towards advancing side aluminum. Mostly, the research was focused on developing high strength joint through microstructural control to reduce IMCs thickness in Al-Mg dissimilar weld joint with optimized processing parameter and appropriate tool offset.
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Date: December 2016
Creator: Poudel, Amir
Partner: UNT Libraries

The Duality of the Hitler Youth: Ideological Indoctrination and Premilitary Education

Description: This thesis examines the National Socialists' ultimate designs for Germany's youth, conveniently organized within the Hitlerjugend. Prevailing scholarship portrays the Hitler Youth as a place for ideological indoctrination and activities akin to the modern Boy Scouts. Furthermore, it often implies that the Hitler Youth was paramilitary but always lacks support for this claim. These claims are not incorrect, but in regard to the paramilitary nature of the organization, they do not delve nearly deeply enough. The National Socialists ultimately desired to consolidate their control over the nation and to prepare the nation for a future war. Therefore, they needed to simultaneously indoctrinate German youth, securing the future existence of National Socialism but also ensuring that German youth carry out their orders and defend Germany, and train the youth in premilitary skills, deliberately attempting to increase the quality of the Wehrmacht and furnish it with a massive, trained reserve in case of war. This paper relies on published training manuals, translated propaganda, memoirs of former Hitler Youth members and secondary literature to examine the form and extent of the ideological indoctrination and premilitary training--which included the general Hitler Youth, special Hitler Youth subdivisions, military preparedness camps akin to boot camp, and elaborate war games which tested the youths' military knowledge. This thesis clearly demonstrates that the National Socialists desired to train the youth in skills that assisted them later in the Wehrmacht and reveals the process implemented by the National Socialists to instill these abilities in Germany's impressionable youth.
Date: December 2016
Creator: Miller, Aaron Michael
Partner: UNT Libraries

The Effects of Feedback Timing when Teaching a New Task to Children with Autism

Description: The purpose of this experiment was to investigate Tosti's proposal about the timing of feedback. The study examined whether it is better to correct immediately after the error occurs or whether it is better to wait until immediately before the next opportunity to respond. In addition, it aimed to determine whether corrections delivered at different times produced different learner affects. Four children with autism were taught to label two sets of pictures under the two different conditions. Results showed that the timing of the feedback yields similar results in regards to number of correct responses and total trial count. However, in regards to time spent in teaching and learner affect, correcting errors before the next opportunity to respond showed to be the more efficient procedure and produced more favorable affect.
Date: December 2016
Creator: Cochrane, Angela
Partner: UNT Libraries

Ethiopian Coffee Stories: Applied Research with Sidama Coffee Farmers Combining Visual and Ethnographic Methods

Description: The purpose of this study is to demonstrate the value of visual research methods to applied anthropology in the context of exploratory research with farmers in Ethiopia. The three methods of photo-elicitation, participatory photography, and ethnographic film, enrich and expand ethnographic methods to support the client's objective of supporting farmers. The applied project constructs a narrative from the local perspective to help consumers learn more about farmers' lives. The research focuses on specific farmers, and their experiences with direct fair trade and coffee farming. The client sees the application of research produced by ethnographic and visual methods as a good direction not only for his company, but the Fair Trade Industry as a whole.
Date: December 2016
Creator: Suter, Paula Jean
Partner: UNT Libraries

Evaluation of Agreement among Respondents to Anecdotal Assessments and Correspondence between Anecdotal and Experimental Analysis Outcomes

Description: Study 1 evaluated agreement among five respondents using the Functional Analysis Screening Tool (FAST), the Motivation Assessment Scale (MAS) and Questions About Behavioral Function (QABF). Respondents provided ratings for 20 target behaviors exhibited by 10 individuals. At least 4/5 raters agreed on the primary maintaining variable in 80% of cases with the FAST, 70% of cases with the MAS, and 55% of cases with the QABF. Study 2 evaluated correspondence between results of anecdotal assessments and experimental functional analysis for 10 target behaviors selected from Study 1. Correspondence between the experimental functional analyses was 60% with the FAST and the MAS, 50% with the QABF.
Date: December 2016
Creator: Frusha, Caroline J.
Partner: UNT Libraries

An Evaluation of Correspondence between Preference and Performance under a Progressive Ration Schedule with College Students

Description: Preference assessments are used in clinical settings to identify stimuli with reinforcing potential. The progressive-ratio schedule has shown to be useful in clinical assessments in identifying stimuli with stronger reinforcer efficacy that corresponds to formalized assessments.The current study utilized a progressive-ratio schedule to compare videos of high and low preference assessed by verbal reports of preference with college students. Results indicated breakpoints were higher for high preferred videos than low preferred videos for three out of five participants, but preference was not indicative of performance.
Date: December 2016
Creator: Johnson, Jamarious
Partner: UNT Libraries

An Evaluation of Interactive Computer Training to Teach Discrete Trial and Naturalistic Instruction to Novice Therapists

Description: Effective and efficient training strategies are needed to provide training to novel therapists whom provide early intensive behavioral intervention (EIBI) services to young children with autism. We evaluated the effects of interactive computer-based training (ICT) on novice therapists' implementation of two, common EIBI instructional techniques: discrete-trial instruction (DTI) and naturalistic instruction. Results demonstrated that ICT improved trainees' instructional fidelity during role-plays with a confederate for DTI instruction and also with a child with autism for both DTI and naturalistic instruction. As a result, the requirement for supervisor feedback on performance was minimized. In addition, results suggest that child language improved as a result of improved therapist performance.
Date: December 2016
Creator: Nielsen, Olivia
Partner: UNT Libraries

An Evaluation of the Effects of Effort on Resistance to Change

Description: Behavioral momentum theory (BMT) has become a prominent method of studying the effects of reinforcement on operant behavior. BMT represents a departure from the Skinnerian tradition in that it identifies the strength of responding with its resistance to change. Like in many other operant research paradigms, however, responses are considered to be momentary phenomena and so little attention has been paid to non-rate dimensions of responding. The current study takes up the question of whether or not the degree of effort defining a discriminated operant class has any meaningful effect on its resistance to change. Using a force transducer, rats responded on a two-component multiple VI 60-s VI 60-s schedule where each component was correlated with a different force requirement. Resistance to change was tested through prefeeding and extinction. Proportional declines in response rate were equal across components during all disruption tests. Differentiated response classes remained intact throughout. The negative result suggests several future research directions.
Date: December 2016
Creator: Foss, Erica K
Partner: UNT Libraries

Exploratory User Research for a Website that Provides Resources for Educators of American Indian Students in Higher Education

Description: Several studies have indicated that American Indian students in the United States higher education system confront unique challenges that derive from a legacy of colonialism and assimilationist policies (Huff 1997). Several scholars, American Indian and non-Native alike, have explored the effects of this history upon students in higher education (Brayboy 2004; Guillory and Wolverton 2008; Waterman and Lindley 2013). Very few, however, have explored the role of the educators of American Indian students, and most of the literature focuses on K-12 educational settings (McCarty and Lee 2014; Yong and Hoffman 2014). This thesis examines exploratory user research conducted to generate a foundational understanding of educators of American Indian students in higher education. Utilizing methods from design anthropology and user experience, semi-structured interviews and think-aloud sessions were conducted, almost exclusively virtually, for 17 participants. This research was conducted for a client, Fire & Associates, as part of the applied thesis process. Findings revealed a complex web of needs for educators of American Indian students in higher education related to teaching diverse students, the use of media and technology in the classroom, and the process of networking among other educators. The research culminated in content and design implications for the Fire & Associates website as well as suggestions for further research based on best practices in the field of user experience.
Date: December 2016
Creator: Roth, Heather S.
Partner: UNT Libraries

Exploring Ahope Client Satisfaction and Attitudes

Description: I led a participatory action research (PAR) project with the staff and homeless clients of Ahope Day Center in Asheville, North Carolina, which was meant to evaluate client satisfaction with services and attitudes about certain issues. Project is led by an inquiry group consisting of members of Ahope staff and Ahope clients. The project is a co-designed, co-implemented, and co-interpreted mixed-method evaluation of Ahope's services, client attitudes about education and the environment, client adaptive strategies, optimism levels, and a mapping of client daily routines. The data was collected through participant observation, document analysis, surveys, a listing activity, and informal interviews. Documents were coded using grounded theory and themes emerged related to the value of the intangibles of security, community, and ‘being seen' at Ahope while some suggestions were also made. Findings included client attitudes indicating the importance of the environment and education to clients, high optimism levels among clients, and a number of suggestions for the improvement of Ahope's services.
Date: December 2016
Creator: Johnston, Josiah Ramsay
Partner: UNT Libraries

Family and Cultural Influences on Latino Emerging Adults' Career Development

Description: There is an extensive amount of research on career development, but most of the constructs studied have focused on content-oriented variables rather than process-oriented variables. While some of the studies have examined samples from ethnic minority populations, the majority of studies use ethnic minority populations as comparison groups, studying between-group differences as opposed to within-group differences. The literature is especially deficient in the are of Latino career development. The current study will examine how family and culture influence the career development of Latino emerging adults. This study will explore the influence of socioeconomic status and acculturation on the career salience and career maturity of Latino emerging adults. The quality of the parent-emerging adult relationship will also be explored for its influence on career development outcomes in this population. One hundred fifty Latino undergraduate students ages 18-24 will be recruited for participation in this study. The participants will complete questionnaires regarding demographic information, acculturation, the quality of the parent-emerging adult relationship, career salience, and career maturity.
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Date: December 2016
Creator: Rodriguez, Kristina
Partner: UNT Libraries

Giving Voice to Multiple Sclerosis: A Patient and Provider Investigation

Description: With the advent of the telephonic and technological healthcare revolution, pharmaceutical corporations seek to improve patient compliance and quality of life by contracting with services providers. As an employee of one such provider, working for more than three years on a medication for the neurologically degenerative disease, multiple sclerosis, this investigation utilizes a mixed methodological approach. In order to improve and diversify the clinical services provided to patients, I was contracted as a consultant. I interviewed phone and PRN nurses, developed and released a PRN survey, and interviewed patients living in the Dallas/Fort Worth, Texas area. The combined experiences and expertise of the three groups who participated would serve to inform and develop new programs and services for patients with differing disease states. The research resulted in a re-imagining of the social networking theory of health, as well as the works of Pierre Bourdieu and Michel Foucault, to serve the evolving tele-health and technologically based healthcare workplace.
Date: December 2016
Creator: Cutler, Alexander
Partner: UNT Libraries

High Driver Turnover among Large Long-Haul Motor Carriers: Causes and Consequences

Description: My thesis provides evidence supporting a theory asserting that the high level of competition that exists between motor carriers operating within long-haul trucking is the most significant factor contributing to the continuously high driver turnover rates affecting the entire logistics industry. I explore how long-haul truck drivers internalize the conflict between their identity and the aggressively competitive environment within which they work. Social science authors, industry reports, and truck driver feedback from my own ethnographic study are analyzed for contexts in order to explore the current operating definition of success for motor carriers in both monetary and human terms.
Date: December 2016
Creator: Ferrell, Christopher Lee
Partner: UNT Libraries

Improving the Long-term Performance of PVC Compositions

Description: PVC are extensively applied in many fields, such as cables, pipes, vehicles, shoes, toys and infusion bags. Generally, plasticizers are blended with PVC to improve the ability of process in industrial production; however, the toxic plasticizers will gradually migrate to the surface of products and such a leakage results in brittleness of plasticized PVC and environmental pollution. In other words, humans are frequently exposed to the potential risks. According to previous researches, cross-linked PVC was proved that it was able to hinder the migration of plasticizer. Thus, in this research, we selected some commercially used cross-linking agents and employed six different tests based on mechanical, tribological and microscopy analysis in order to seek the best solution against plasticizer migration. Thus, we expected to develop a cross-linked flexible PVC which performed improved long-term performance and extended lifetime.
Date: December 2016
Creator: Yang, Yu Chia
Partner: UNT Libraries

Increasing Number of Toys: A Case Study of Response Generalization across Novel Toys

Description: Children diagnosed with autism are often described as having limited or restricted activities that serve as reinforcers as compared to neurotypical peers. Many theories suggest that one of the many ways children develop is through participation in play. This results in children coming into contact with new environmental stimuli. The procedures used to enhance play skills for children diagnosed with autism typically involve training novel responses with novel stimuli (e.g., toys). This is often done using naturalistic procedures. Because multiple procedures are used, it is unclear what procedure or combination of procedures causes the increases in play repertoires. This study investigated an important component of the treatment package know as reciprocal imitation training. Specifically, the study examined whether increased opportunities, contingent imitation without the requirement to imitate, or contingent imitation with the requirement to imitate would increase the number of toys a child diagnosed with autism would play with. The results showed dramatic increases in the number of toys the child independently chose to play with and an increase in the spontaneous use of different response topographies across novel stimuli only when the student was required to imitate a model. The results are discussed in terms of mediated generalization, the use of common responses, stimulus class formation and stimulus class expansion.
Date: December 2016
Creator: Chaudhry, Mohsana
Partner: UNT Libraries

The Influence of Population on Wrongful Convictions

Description: With criminal cases continuing to be exonerated across the United States, research must be done on the subject to advance current practices to reduce its occurrence in the future. This study combines county population data with the National Registry of Exonerations to analyze the contributing factors to wrongful convictions and the possible effect of population on their frequency. The objective of this study was to identify specific policy changes based on the five contributing factors to wrongful convictions that could be applied to population specific areas. The results yielded multiple patterns that are discussed thoroughly. These findings allowed the introduction of policy changes and proposals for future research.
Date: December 2016
Creator: Whittington, Kari
Partner: UNT Libraries

Memory and Continuity Amidst Irreversible Decline in the Texas Big Empty

Description: This thesis interrogates sense of place and place attachment in the Big Empty on the north central Texas plains. The region stretches from the Red River on the north to the Colorado River basin on the south and from the Cross Timbers on the east to the Caprock escarpment on the west. Since 1930, the Big Empty has seen sustained and severe population decline such that some counties there now register less than a quarter the population they did at their peaks during the interwar years. Through in-depth field interviews, I examine sense of place and place attachment amidst apparently irreversible decline. I also describe conditions of postindustrial rurality arising from rolling reconfigurations of economic and social relations, particularly changes in scale in farming and the diminished centrality of productivist agriculture in local economies and culture, and how these conditions become legible through the study of place.
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Date: December 2016
Creator: Underwood, Robert Reed
Partner: UNT Libraries

Modeling of Fracture Toughness of Magnesium Alloy WE43 Before and After Friction Stir Processing

Description: Magnesium alloys are a popular research topic for structural applications because they have a lower density than conventional structural materials, including steel, titanium, and aluminum; however, the reliability and safety of their mechanical properties must be further proven. An important mechanical property for this purpose is fracture toughness, which is the measure of the material's resistance to crack propagation. In this study, a model of an experiment to investigate the fracture toughness of a magnesium alloy WE43 before and after friction stir processing (FSP) is developed, and the results are compared to those produced by a digital image correlation (DIC) system during an experiment from another paper. The model results of the material before FSP matched well with the DIC results, but the model of the material after FSP only partially matches the DIC results. In addition, a theoretical approach to calculating the standard fracture toughness value, KIc, from the modeling results is proposed, and is found to be a conservative approach.
Date: December 2016
Creator: Lipscomb, Celena Andrea
Partner: UNT Libraries

Modeling of Hexagonal Boron Nitride Filled Bismalemide Polymer Composites for Thermal and Electrical Properties for Electronic Packaging

Description: Due to the multi-tasking and miniaturization of electronic devices, faster heat transfer is required from the device to avoid the thermal failure. Die-attached polymer adhesives are used to bond the chips in electronic packaging. These adhesives have to hold strong mechanical, thermal, dielectric, and moisture resistant properties. As polymers are insulators, heat conductive particles are inserted in it to enhance the thermal flow with an attention that there would be no electrical conductivity as well as no reduction in dielectric strength. This thesis focuses on the characterization of polymer nanocomposites for thermal and electrical properties with experimental and computational tools. Platelet geometry of hexagonal boron nitride offers highly anisotropic properties. Therefore, their alignment and degree of orientation offers tunable properties in polymer nanocomposites for thermal, electrical, and mechanical properties. This thesis intends to model the anisotropic behavior of thermal and dielectric properties using finite element and molecular dynamics simulations as well as experimental validation.
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Date: December 2016
Creator: Uddin, Md Salah
Partner: UNT Libraries

Musical Ekphrasis in the Poetry of Nicolás Guillén, Federico García Lorca, and Langston Hughes

Description: Musical ekphrasis was occurring in the twentieth century in different centers around the world, Cuba: Andalusia, Spain; and Harlem, New York, simultaneously. The writers at the heart of this movement used poetry about music as a means to celebrate the cultures of the marginalized people in their lands, los negros, los gitanos, and African-Americans. The purpose of this study is to define musical ekphrasis and identify it in the works of Nicolás Guillén, Federico García Lorca, and Langston Hughes. Also explored are the common characteristics in ekphrastic poetry by the three poets and the common themes found in their ekphrastic poetry, as well as common influences. Each author is considered in the context of his surroundings and his respective culture, and how that influenced his musical tastes as well as his writing style.
Date: December 2016
Creator: Divett, Andrew Brennan
Partner: UNT Libraries

Negotiated Living: An Ethno-Historical Perspective of Punta Allen

Description: Situated within the jurisdiction of the Municipality of Tulum and within the Sian Ka'an Biosphere gives the village of Punta Allen a distinctive agency in determining their role in the on-going development of tourism in the region that is not given to other communities in the state. This unique circumstance facilitates a dialogue between the reserve, the municipality, and the business cooperatives of Punta Allen that produce a negotiated living. Through the negotiations with the reserve and Tulum, the lobster fishing and tourism cooperatives are given the opportunity to have a relatively significant role in determining the future of Punta Allen in regards to tourism.
Date: December 2016
Creator: McRae, David Thomas
Partner: UNT Libraries

Parcel-Based Change Detection Using Multi-Temporal LiDAR Data in the City of Surrey, British Columbia, Canada

Description: Change detection is amongst the most effective critical examination methods used in remote sensing technology. In this research, new methods are proposed for building and vegetation change detection using only LiDAR data without using any other remotely sensed data. Two LiDAR datasets from 2009 and 2013 will be used in this research. These datasets are provided by the City of Surrey. A Parcel map which shows parcels in the study area will be also used in this research because the objective of this research is detecting changes based on parcels. Different methods are applied to detect changes in buildings and vegetation respectively. Three attributes of object –slope, building volume, and building height are derived and used in this study. Changes in buildings are not only detected but also categorized based on their attributes. In addition, vegetation change detection is performed based on parcels. The output shows parcels with a change of vegetation. Accuracy assessment is done by using measures of completeness, correctness, and quality of extracted regions. Accuracy assessments suggest that building change detection is performed with better results.
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Date: December 2016
Creator: Yigit, Aykut
Partner: UNT Libraries

Particle Image Velocimetry Sensitivity Analysis Using Automatic Differentiation

Description: A particle image velocimetry (PIV) computer software is analyzed in this work by applying automatic differentiation on it. We create two artificial images that contained particles that where moved with a known velocity field over time. These artificial images were created with parameters that we would have on real PIV experiments. Then we applied a PIV software to find the velocity output vectors. As we mentioned before, we applied automatic differentiation through all the algorithm to track the derivatives of the output vectors regarding interesting parameters declared as inputs. By analyzing these derivatives we analyze the sensitivity of the output vectors to changes on each one of the parameters analyzed. One of the most important derivatives calculated in this project was the derivative of the output regarding the image intensity. In future work we plan to use this derivative combined with the intensity probability distribution of each image pixel, to find PIV uncertainties. If we achieve this goal we will find an uncertainty method that will save computational power and will give uncertainty values with computer accuracy.
Date: December 2016
Creator: Grullon Varela, Rodolfo Antonio
Partner: UNT Libraries

Privacy Preserving EEG-based Authentication Using Perceptual Hashing

Description: The use of electroencephalogram (EEG), an electrophysiological monitoring method for recording the brain activity, for authentication has attracted the interest of researchers for over a decade. In addition to exhibiting qualities of biometric-based authentication, they are revocable, impossible to mimic, and resistant to coercion attacks. However, EEG signals carry a wealth of information about an individual and can reveal private information about the user. This brings significant privacy issues to EEG-based authentication systems as they have access to raw EEG signals. This thesis proposes a privacy-preserving EEG-based authentication system that preserves the privacy of the user by not revealing the raw EEG signals while allowing the system to authenticate the user accurately. In that, perceptual hashing is utilized and instead of raw EEG signals, their perceptually hashed values are used in the authentication process. In addition to describing the authentication process, algorithms to compute the perceptual hash are developed based on two feature extraction techniques. Experimental results show that an authentication system using perceptual hashing can achieve performance comparable to a system that has access to raw EEG signals if enough EEG channels are used in the process. This thesis also presents a security analysis to show that perceptual hashing can prevent information leakage.
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Date: December 2016
Creator: Koppikar, Samir Dilip
Partner: UNT Libraries