UNT Libraries - 925 Matching Results

Search Results

Note: All results matching your query require you to be a member of the UNT Community (you must be on campus or login with university credentials for access).

The Acceptance and Use of Cloud Computing Services by Small and Medium Enterprises in Lagos, Nigeria

Description: This study explored the acceptance of cloud computing (CC) services by small and medium enterprises (SMEs) in Lagos, Nigeria, which has been missing from CC services literature. It aimed to understand the motivations for adoption, the uses of the services, and the benefits they derive from it. The uses and gratification theory was applied as the theoretic framework for this endeavor. An online survey with close-ended and open-ended questions was distributed to 1200 randomly selected participants through email. In total, 392 valid responses were collected and analyzed using descriptive statistics and categories. The results found that SMEs in Lagos, Nigeria had a low level of awareness and appreciation of CC services. The adoption rate was also low. Unlike their counterparts in other regions, SMEs primary concerns were service downtime, stable power supply, and better internet access. The study found that SMEs were not taking full advantage of the capabilities of CC services. Some sections, however, were doing better than others, such as the information and communications sub-sector. This study suggested that targeted interventions should be conducted to raise the awareness of CC services in SMEs, and to improve their efficient and effective use of CC services. The uses and gratification theory was appropriate for guiding this study to understand the acceptance and use of CC services by SMEs in Lagos, Nigeria.
Date: May 2017
Creator: Azogu, Olajumoke O

Age Friendly Cities: The Bureaucratic Responsiveness Effects on Age Friendly Policy Adoption

Description: Challenging a long-held attachment to the medical model, this research develops a cultural model placing local governments at the center of policy making and refocusing policy attention on mobility, housing, the built environment and services. To examine the phenomenon of age friendly policy adoption by cities and the magnitude of adoption, a 21-question web-based survey was administered to a sample of 1,050 cities from the U.S. Census having a population over 10,000 and having at least 14% of their population aged 65 years and over. The goal of the questionnaire was to help identify what kind of policy objectives cities establish to facilitate the opportunity for older adults to live healthy and independent lives in their communities as they age. Multiple linear and ordinal regression models examined the likelihood of policy action by cities and provide evidence as to why some cities support more age friendly policy actions than others. Evidence illustrates theoretical advancement providing support for a cultural model of aging. The cultural model includes multiple factors including bureaucratic responsiveness reflected in the management values of the administration. Findings show variation in the integration of a cultural awareness of aging in the municipality's needs assessment, strategic goals, citizen engagement strategies, and budgetary principles. Cities with a cultural awareness of aging are more likely to adopt age friendly policies. Findings also provide support for the argument that the public administrator is not the driving sole factor in decision making. A shared spaced with mobilized citizen need of individuals 65 and over is identified.
Date: May 2017
Creator: Keyes, Laura Marie

Becoming Successful in Education: Beating the Odds, Despite a Background Entrenched in Poverty

Description: The purpose of this study was to investigate the impact of three relationships on academic achievement in mathematics in students of poverty. The three factors that were examined included: teacher-student relationships, parent-student relationships and peer- student relationships. The driving question for the research was as follows: Do external factors such as teacher-student relationships, parent-student relationships and peer-student relationships lead to academic success for students of poverty? The study employed a non-experimental, quantitative approach and utilized longitudinal data from a national database High School Longitudinal Study (HSLS) used a sample of 944 public and private high schools across the USA. A total 0f 28,240 were represented in the survey. Of these 28,240 students, 2641 were used in this study as identified by parental income below the poverty threshold. The outcome of the study indicated that there was little or no correlation between the three relationships and mathematics achievement (academic success). Correlations between the dependent variable (math achievement) and the independent variables even though some were statistically significant their weights had no concrete significance. The study recommends that several initiatives can be instated in schools to support and enhance academic achievement in students of poverty.
Date: May 2017
Creator: Thompson, Pauline A

Brain Computer Interface (BCI) Applications: Privacy Threats and Countermeasures

Description: In recent years, brain computer interfaces (BCIs) have gained popularity in non-medical domains such as the gaming, entertainment, personal health, and marketing industries. A growing number of companies offer various inexpensive consumer grade BCIs and some of these companies have recently introduced the concept of BCI "App stores" in order to facilitate the expansion of BCI applications and provide software development kits (SDKs) for other developers to create new applications for their devices. The BCI applications access to users' unique brainwave signals, which consequently allows them to make inferences about users' thoughts and mental processes. Since there are no specific standards that govern the development of BCI applications, its users are at the risk of privacy breaches. In this work, we perform first comprehensive analysis of BCI App stores including software development kits (SDKs), application programming interfaces (APIs), and BCI applications w.r.t privacy issues. The goal is to understand the way brainwave signals are handled by BCI applications and what threats to the privacy of users exist. Our findings show that most applications have unrestricted access to users' brainwave signals and can easily extract private information about their users without them even noticing. We discuss potential privacy threats posed by current practices used in BCI App stores and then describe some countermeasures that could be used to mitigate the privacy threats. Also, develop a prototype which gives the BCI app users a choice to restrict their brain signal dynamically.
Date: May 2017
Creator: Bhalotiya, Anuj Arun

Case Studies to Learn Human Mapping Strategies in a Variety of Coarse-Grained Reconfigurable Architectures

Description: Computer hardware and algorithm design have seen significant progress over the years. It is also seen that there are several domains in which humans are more efficient than computers. For example in image recognition, image tagging, natural language understanding and processing, humans often find complicated algorithms quite easy to grasp. This thesis presents the different case studies to learn human mapping strategy to solve the mapping problem in the area of coarse-grained reconfigurable architectures (CGRAs). To achieve optimum level performance and consume less energy in CGRAs, place and route problem has always been a major concern. Making use of human characteristics can be helpful in problems as such, through pattern recognition and experience. Therefore to conduct the case studies a computer mapping game called UNTANGLED was analyzed as a medium to convey insights of human mapping strategies in a variety of architectures. The purpose of this research was to learn from humans so that we can come up with better algorithms to outperform the existing algorithms. We observed how human strategies vary as we present them with different architectures, different architectures with constraints, different visualization as well as how the quality of solution changes with experience. In this work all the case studies obtained from exploiting human strategies provide useful feedback that can improve upon existing algorithms. These insights can be adapted to find the best architectural solution for a particular domain and for future research directions for mapping onto mesh-and- stripe based CGRAs.
Date: May 2017
Creator: Malla, Tika Kumari

Catalytic Properties and Mechanical Behavior of Metallic Glass Powders

Description: Lack of crystalline order and microstructural features such as grain/grain-boundary in metallic glasses results in a suite of remarkable attributes including very high strength, close to theoretical elasticity, high corrosion and wear resistance, and soft magnetic properties. By altering the morphology and tuning of composition, MGs may be transformed into high-performance catalytic materials. In this study, the catalytic properties of metallic glass powders were demonstrated in dissociating toxic organic chemicals such as AZO dye. BMG powders showed superior performance compared to state of the art crystalline iron because of their high catalytic activity, durability, and reusability. To enhance the catalytic properties, high energy mechanical milling was performed to increase the surface area and defect density. Iron-based bulk metallic glass (BMG) of composition Fe48Cr15Mo14Y2C15B6 was used because of its low cost and ability to make large surface area by high energy ball milling. AZO dye was degraded in less than 20 minutes for the 9 hours milled Fe-BMG. However, subsequent increase in ball milling time resulted in devitrification and loss of catalytic activity as measured using UV-Visible spectroscopy. Aluminum-based bulk metallic glass (Al-BMG) powder of composition Al82Fe3Ni8Y7 was synthesized by arc-melting the constituent elements followed by gas-atomization. The particle size and morphology were similar to Fe-BMG with a fully amorphous structure. A small percentage of transition metal constituents (Fe and Ni) in a mostly aluminum alloy showed high catalytic activity, with no toxic by-products and no change in surface characteristics. Al-alloy particles, being light-weight, were easily dispersed in aqueous medium and accelerated the redox reactions. The mechanism of dye dissociation was studied using Raman and Infrared (IR) spectroscopy. Breaking of -C-H- and - C-N- bonds of AZO dye was found to be the primary mechanism. Mechanical behavior of individual BMG particles was evaluated by in situ pico-indentation in a scanning electron ...
Date: May 2017
Creator: Garrison, Seth Thomas

Characteristics of Mothers among Counselor Education Faculty

Description: Pre-tenured faculty in higher education and as well as mothers have reportedly struggled with low wellness levels, high demands, little social support, and an imbalance of work and home life. Mothers in higher education and in counselor education have reported struggling with work-life balance, high scholarly productivity, and long hours as well as the emotional and physical energy demands of working with counselors-in-training. A search of the professional literature revealed a paucity of quantitative research regarding demographic characteristics, wellness levels, and social support levels of mothers among counselor education faculty (MCEs). Participants for this study were faculties of counselor education programs recruited from the Holland List of Counseling Programs and from the Council for Accreditation of Counseling and Related Educational Programs online directory. A total of 180 MCEs participated (aged 29-63, with mean age 40.6 years; 83% Caucasian, 8% other, 5% African American, 3% Hispanic, <1% Asian). Results showed that faculty rank did not account for a significant difference among wellness scores of MCEs and that reported social support, tenure or non-tenure track, number of children in the care of MCEs, number of children under age 8, number of publications, and teaching workload accounted for 14% of the variance in wellness levels of MCEs. Specifically, reported higher teaching workload (β = -.194, rs2 = .35, p = .012) and higher social support (β = -.258, rs2 = .36, p = <.001) were found to be significant predictors of lower wellness levels among MCEs, both with small effects. Based on these results, MCEs may benefit from advocating that their departments and universities adapt to their unique needs to improve their levels of wellness and social support through mentoring, which, in turn, may result in not only their own increased productivity but also their students' increased wellness levels.
Date: May 2017
Creator: Jimenez, Kyrstin Anne

Collective Security and Coalition: British Grand Strategy, 1783-1797

Description: On 1 February 1793, the National Convention of Revolutionary France declared war on Great Britain and the Netherlands, expanding the list of France's enemies in the War of the First Coalition. Although British Prime Minister William Pitt the Younger had predicted fifteen years of peace one year earlier, the French declaration of war initiated nearly a quarter century of war between Britain and France with only a brief respite during the Peace of Amiens. Britain entered the war amid both a nadir in British diplomacy and internal political divisions over the direction of British foreign policy. After becoming prime minister in 1783 in the aftermath of the War of American Independence, Pitt pursued financial and naval reform to recover British strength and cautious interventionism to end Britain's diplomatic isolation in Europe. He hoped to create a collective security system based on the principles of the territorial status quo, trade agreements, neutral rights, and resolution of diplomatic disputes through mediation - armed mediation if necessary. While his domestic measures largely met with success, Pitt's foreign policy suffered from a paucity of like-minded allies, contradictions between traditional hostility to France and emergent opposition to Russian expansion, Britain's limited ability to project power on the continent, and the even more limited will of Parliament to support such interventionism. Nevertheless, Pitt's collective security goal continued to shape British strategy in the War of the First Coalition, and the same challenges continued to plague the British war effort. This led to failure in the war and left the British fighting on alone after the Treaty of Campo Formio secured peace between France and its last continental foe, Austria, on 18 October 1797.
Date: May 2017
Creator: Jarrett, Nathaniel W

Community College Student Retention and Completion based on Financial Expenditures and Hispanic-Serving Status

Description: Despite declining community college funding being allocated increasingly on the basis of student success, U.S. community college student retention and completion rates over the past decade have either remained steady or decreased, especially for Latino students. Using descriptive statistics and multiple regression models with secondary data procured from the Integrated Postsecondary Education Data System (IPEDS), I analyzed student success rates—full time student retention and completion rates—based on community college financial allocations and Hispanic-serving institution (HSI) status. To equitably analyze community colleges in the sample (n = 909), I separated them into four groups based on institutional size as defined by the Carnegie Classification. Descriptive results indicated that instructional divisions spent an average of 43% of the college's total allocated budget—often more than three times the allocated budget of any other division. Regression results indicated that instructional expenditures had the most consistent impact on student success regardless of college size and that scholarship expenditures and academic support expenditures generally had a negative impact on student retention and completion rates. Regarding Latino student success in particular, findings indicated that the manner in which colleges allocated their funds impacted only small and medium-sized community colleges. Of the nine different types of institutional expenditures, only student services expenditures and public services expenditures had a statistically significant impact on Latino student success. Additionally regression analysis indicated that community college HSI status did not have a large impact on overall full-time student retention and completion rates but did have a significant impact on full-time Hispanic student retention and completion rates for all institution sizes. Findings of this study confirmed that HSI status does impact Latino student success in public community colleges. This finding is consistent with prior studies on the positive impact of instructional expenditures on student success rates. Further research on the specific elements within ...
Date: May 2017
Creator: DaSilva, Jose E.

Design Considerations and Implementation of Portable Mass Spectrometers for Environmental Applications

Description: Portable mass spectrometers provide a unique opportunity to obtain in situ measurements. This minimizes need for sample collection or in laboratory analysis. Membrane Inlet Mass Spectrometry (MIMS) utilizing a semi permeable membrane for selective rapid introduction for analysis. Polydimethylsiloxane membranes have been proven to be robust in selecting for aromatic chemistries. Advances in front end design have allowed for increased sensitivity, rapid sample analysis, and on line measurements. Applications of the membrane inlet technique have been applied to environmental detection of clandestine drug chemistries and pollutants. Emplacement of a mass spectrometer unit in a vehicle has allowed for large areas to be mapped, obtaining a rapid snapshot of the various concentrations and types of environmental pollutants present. Further refinements and miniaturization have allowed for a backpackable system for analysis in remote harsh environments. Inclusion of atmospheric dispersion modeling has yielded an analytical method of approximating upwind source locations, which has law enforcement, military, and environmental applications. The atmospheric dispersion theories have further been applied to an earth based separation, whereby chemical properties are used to approximate atmospheric mobility, and chemistries are further identified has a portable mass spectrometer is traversed closer to a point source.
Date: May 2017
Creator: Mach, Phillip Michael

Determinants of Corporate Governance Choices: Evidence from Listed Foreign Firms on U.S. Stock Exchanges

Description: This study analyzes corporate governance practices of foreign (non-U.S.) issuers listed on the New York Stock Exchange (NYSE) and Nasdaq. Specifically, I examine the extent to which these foreign issuers voluntarily comply with U.S. stock exchange corporate governance requirements applicable to domestic issuers. My sample consists of 201 foreign companies primarily domiciled in Brazil, China, Israel, and the United Kingdom. I find that 151 (75 per cent) of the sample firms do not elect to comply with any of the U.S. corporate governance requirements. Logistic regression analysis generally supports the hypotheses that conformance with U.S. GAAP and percentage of managerial ownership are positively associated, and that percentage ownership by major shareholders is negatively associated with foreign firms electing to comply with U.S. corporate governance rules. This evidence is relevant for regulators and investors.
Date: May 2017
Creator: Attachot, Weerapat

Development of an Outcome Measure for Use in Psychology Training Clinics

Description: The ability to monitor client change in psychotherapy over time is vital to quality assurance in service delivery as well as the continuing improvement of psychotherapy research. Unfortunately, there is not currently a comprehensive, affordable, and easily utilized outcome measure for psychotherapy specifically normed and standardized for use in psychology training clinics. The current study took the first steps in creating such an outcome measure. Following development of an item bank, factor analysis and item-response theory analyses were applied to data gathered from a stratified sample of university (n = 101) and community (n = 261) participants. The factor structure did not support a phase model conceptualization, but did reveal a structure consistent with the theoretical framework of the research domain criteria (RDoC). Suggestions for next steps in the measure development process are provided and implications discussed.
Date: May 2017
Creator: Davis, Elizabeth C.

Effectiveness of Fillers for Corrosion Protection of AISI-SAE 1018 Steel in Sea Salt Solution

Description: Corrosion represents the single most frequent cause for product replacement or loss of product functionality with a 5% coat to the industrial revenue generation of any country in this dissertation the efficacy of using filled coatings as a protection coating are investigated. Fillers disrupt the polymer-substrate coating interfacial area and lead to poor adhesion. Conflicting benefits of increasing surface hardness and corrosion with long term durability through loss of adhesion to the substrate are investigated. The effects of filler type, filler concentration and exposure to harsh environments such as supercritical carbon dioxide on salt water corrosion are systematically investigated. The constants maintained in the design of experiments were the substrate, AISI-SAE 1018 steel substrate, and the corrosive fluid synthetic sea salt solution (4.2 wt%) and the polymer, Bismaleimide (BMI). Adhesion strength through pull-off, lap shear and shear peel tests were determined. Corrosion using Tafel plots and electrochemical impedance spectroscopy was conducted. Vickers hardness was used to determine mechanical strength of the coatings. SEM and optical microscopy were used to examine dispersion and coating integrity. A comparison of fillers such as alumina, silica, hexagonal boron nitride, and organophilic montmorillonite clay (OMMT) at different concentrations revealed OMMT to be most effective with the least decrease in adhesion from filler-substrate contact. Subsequently examining filler concentration, a 3 wt% OMMT was found to be most effective. A comparison of unmodified and modified BMI with 3 wt% OMMT exposed and not exposed to supercritical carbon dioxide showed that the BMI provided better corrosion protection; however, OMMT provided better wear, shear, and hardness performance.
Date: May 2017
Creator: Al-Shenawa, Amaal Abdallah Ali

The Effects of Air Pollution on the Intestinal Microbiota: A Novel Approach to Assess How Gut Microbe Interactions with the Environment Affect Human Health

Description: This thesis investigates how air pollution, both natural and anthropogenic, affects changes in the proximal small intestine and ileum microbiota profile, as well as intestinal barrier integrity, histological changes, and inflammation. APO-E KO mice on a high fat diet were randomly selected to be exposed by whole body inhalation to either wood smoke (WS) or mixed vehicular exhaust (MVE), with filtered air (FA) acting as the control. Intestinal integrity and histology were assessed by observing expression of well- known structural components tight junction proteins (TJPs), matrix metallopeptidase-9 (MMP-9), and gel-forming mucin (MUC2), as well known inflammatory related factors: TNF-α, IL-1β, and toll-like receptor (TLR)-4. Bacterial profiling was done using DNA analysis of microbiota within the ileum, utilizing 16S metagenomics sequencing (Illumina miSeq) technique. Overall results of this experiment suggest that air pollution, both anthropogenic and natural, cause a breach in the intestinal barrier with an increase in inflammatory factors and a decrease in beneficial bacteria. This evidence suggests the possibility of air pollution being a potential causative agent of intestinal disease as well as a possible contributing mechanism for induction of systemic inflammation.
Date: May 2017
Creator: Fitch, Megan

Effects of Student-Created Question Process on Learning Biomedical Statistics in a Specialized Master's in Medical Sciences

Description: This study explored the effectiveness of a student question creation process engaging students actively in self, peer, and instructor interaction in development of affective, cognitive, and meta-cognitive skills. Employing a mixed-methods sequential explanatory design assigning both treatment and control activities sequentially in an alternating pattern over a six week period, students' performance on exams as well as their perceptions of various aspects of the student question creation process were used to evaluate the effectiveness of student-created questions (SCQs) activities as a cognitive strategy and to identify factors contributing to the effectiveness of question creation activities on students' learning. Subjects of this study were high performing and highly motivated graduate students in an 8-week online biomedical statistics course, part of a specialized master's program designed for medical school preparation. Survey findings and focus groups strongly supported the student question creation process as a facilitator of higher order thinking. However, the relatively short study duration, comparison of student question creation with another competing method for facilitating learning (discussion board) and not a pure control group, and availability of a common study guide course with student-created questions on all course topics may have muted assessment of the full impact of the strategy on learning. Although practically difficult in an education environment, further research to assess fully the impact of the student question creation strategy is desirable especially if these confounding factors can be greatly minimized, if not eliminated.
Date: May 2017
Creator: Bashet, Abuzafar

Exceptional Properties in Friction Stir Processed Beta Titanium Alloys and an Ultra High Strength Steel

Description: The penchant towards development of high performance materials for light weighting engineering systems through various thermomechanical processing routes has been soaring vigorously. Friction stir processing (FSP) - a relatively new thermomechanical processing route had shown an excellent promise towards microstructural modification in many Al and Mg alloy systems. Nevertheless, the expansion of this process to high temperature materials like titanium alloys and steels is restricted by the limited availability of tool materials. Despite it challenges, the current thesis sets a tone for the usage of FSP to tailor the mechanical properties in titanium alloys and steels. FSP was carried out on three near beta titanium alloys, namely Ti6246, Ti185 and Tiβc with increasing β stability index, using various tool rotation rates and at a constant tool traverse speed. Microstructure and mechanical property relationship was studied using experimental techniques such as SEM, TEM, mini tensile testing and synchrotron x-ray diffraction. Two step aging on Ti6246 had resulted in an UTS of 2.2GPa and a specific strength around 500 MPa m3/mg, which is about 40% greater than any commercially available metallic material. Similarly, FSP on an ultra-high strength steel―Eglin steel had resulted in a strength greater than 2GPa with a ductility close to 10% at around 4mm from the top surface of stir zone (SZ). Experimental techniques such as microhardness, mini-tensile testing and SEM were used to correlate the microstructure and properties observed inside SZ and HAZ's of the processed region. A 3D temperature modeling was used to predict the peak temperature and cooling rates during FSP. The exceptional strength ductility combinations inside the SZ is believed to be because of mixed microstructure comprised of various volume fractions of phases such as martensite, bainite and retained austenite.
Date: May 2017
Creator: Tungala, Vedavyas

A Guide to Franz Liszt's Piano Transcriptions of Franz Schubert's Songs

Description: Franz Liszt (1811-1886) made fifty-six transcriptions of Schubert's songs over a period of eight years (1838-46) to introduce the name of the composer, who was little known both in and outside Vienna during his lifetime. Because Liszt intentionally preserved all the details of the original songs, these transcriptions present challenges for a pianist, such as how to produce a vocal line on the piano, as well as interpretive issues such as ornamentation, style, and conveying the meaning of the lyrics on the piano. The purpose of this study is to introduce pianists to study practices employed by singers, with the goal of interpreting the vocal aspects of Liszt's Schubert song transcriptions. The composer Robert Schumann once remarked that Liszt's transcriptions were perhaps the most difficult pieces written for the piano up to that time, and only an intelligent artist could satisfy Liszt's high level of virtuosity without destroying the identity of the original work. This could be considered a warning to pianists not to focus on the technical aspects only. The pedagogical guide presented in the study, based on singers' approaches to the actual songs, should help pianists to "see beyond the notes" and achieve a performance closer to the heart of the songs.
Date: May 2017
Creator: Kim, Ah Young

The Impact of Causative Genes on Neuropsychological Functioning in Familial Early-Onset Alzheimer's Disease: A Meta-Analysis

Description: Mutations of three genes encoding amyloid precursor protein (APP), presenilin-1 (PSEN1), and presenilin-2 (PSEN2) have been shown to reliably result in familial early-onset Alzheimer's disease (FAD); a rare, but catastrophic, subtype of Alzheimer's disease (AD) marked by symptom emergence before age 65 as well as accelerated cognitive deterioration. The current study represents the first known meta-analysis on the association of APP, PSEN1 or PSEN2 on neurocognitive variables. A total of 278 FAD mutation-carriers (FAD-MC) and 284 cognitively healthy non-mutation-carriers (NC) across 10 independent investigations meeting inclusion criteria were chosen for the current meta-analysis (random effects design). Findings revealed an overarching trend of poorer performance by FAD-MC individuals compared to NC individuals across the majority of cognitive domains identified. Significant differences in effect sizes suggested FAD-MC individuals exhibited worse performance on measures of attention, explicit memory, fluency, primary memory, verbal, and visuospatial functioning. Findings indicative of differential sensitivity to cognitive domain impairments across FAD-MC and NC groups inform neuropsychological descriptions of individuals in preclinical phases of FAD.
Date: May 2017
Creator: Smotherman, Jesse M

Improving the Gameplay Experience and Guiding Bottom Players in an Interactive Mapping Game

Description: In game based learning, motivating the players to learn by providing them a desirable gameplay experience is extremely important. However, it's not an easy task considering the quality of today's commercial non-educational games. Throughout the gameplay, the player should neither get overwhelmed nor under-challenged. The best way to do so is to monitor the player's actions in the game because these actions can tell the reason behind the player's performance. They can also tell about the player's lacking competencies or knowledge. Based on this information, in-game educational interventions in the form of hints can be provided to the player. The success of such games depends on their interactivity, motivational outlook and thus player retention. UNTANGLED is an online mapping game based on crowd-sourcing, developed by Reconfigurable Computing Lab, UNT for the mapping problem of CGRAs. It is also an educational game for teaching the concepts of reconfigurable computing. This thesis performs qualitative comparative analysis on gameplays of low performing players of UNTANGLED. And the implications of this analysis are used to provide recommendations for improving the gameplay experience for these players by guiding them. The recommendations include strategies to reach a high score and a compact solution, hints in the form of preset patterns and a clustering based approach.
Date: May 2017
Creator: Ambekar, Kiran

Microstructural Evolution and Mechanical Response of Materials by Design and Modeling

Description: Mechanical properties of structural materials are highly correlated to their microstructure. The relationship between microstructure and mechanical properties can be established experimentally. The growing need for structural materials in industry promotes the study of microstructural evolution of materials by design using computational approaches. This thesis presents the microstructural evolution of two different structural materials. The first uses a genetic algorithm approach to study the microstructural evolution of a high-temperature nickel-based oxide-dispersion-strengthened (ODS) alloy. The chosen Ni-20Cr ODS system has nano Y2O3 particles for dispersion strengthening and submicron Al2O3 for composite strengthening. Synergistic effects through the interaction of small dispersoids and large reinforcements improved high-temperature strength. Optimization considered different weight factors on low temperature strength, ductility, and high temperature strength. Simulation revealed optimal size and volume fraction of dispersoids and reinforced particles. Ni-20Cr-based alloys were developed via mechanical alloying for computational optimization and validation. The Ni-20Cr-1.2Y2O3-5Al2O3 alloy exhibited significant reduction in the minimum creep rate (on the order of 10-9 s-1) at 800oC and 100 MPa. The second considers the microstructural evolution of AA 7050 alloy during friction stir welding (FSW). Modeling the FSW process includes thermal, material flow, microstructural and strength modeling. Three-dimensional material flow and heat transfer model was developed for friction stir welding process of AA 7050 alloy to predict thermal histories and extent of deformation. Peak temperature decreases with the decrease in traverse speed at constant advance per revolution, while the increase in tool rotation rate enhances peak temperature. Shear strain is higher than the longitudinal and transverse strain for lower traverse speed and tool rotation rate; whereas for higher traverse speed and tool rotation rate, shear and normal strain acquire similar values. Precipitation distribution simulation using TC-PRISMA predicts the presence of η' and η in the as-received AA 7050-T7451 alloy and mostly η in the friction ...
Date: May 2017
Creator: Dutt, Aniket Kumar

Misrecognized and Misplaced: Race Performed in African American Literature, 1900-2015

Description: In my dissertation, I explore the ways in which racial identity is made complex through various onlookers' misrecognition of race. This issue is particularly important considering the current state of race relations in the United States, as my project offers a literary perspective and account of the way black authors have discussed racial identity formation from the turn of the century through the start of the twenty-first century. I highlight many variations of misrecognition and racial performance as a response to America's obsession with race.
Date: May 2017
Creator: Taylor Juko, Tana

Nonlinear Light Generation from Optical Cavities and Antennae

Description: Semiconductor based micro- and nano-structures grown in a systematic and controlled way using selective area growth are emerging as a promising route toward devices for integrated optical circuitry in optoelectronics and photonics field. This dissertation focuses on the experimental investigation of the nonlinear optical effects in selectively grown gallium nitride micro-pyramids that act as optical cavities, zinc oxide submicron rods and indium gallium nitride multiple quantum well core shell submicron tubes on the apex of GaN micro pyramids that act as optical antennae. Localized spatial excitation of these low dimensional semiconductor structures was optimized for nonlinear optical light (NLO) generation due to second harmonic generation (SHG) and multi-photon luminescence (MPL). The evolution of both processes are mapped along the symmetric axis of the individual structures for multiple fundamental input frequencies of light. Effects such as cavity formation of generated light, electron-hole plasma generation and coherent emission are observed. The efficiency and tunability of the frequency conversion that can be achieved in the individual structures of various geometries are estimated. By controlling the local excitation cross-section within the structures along with modulation of optical excitation intensity, the nonlinear optical process generated in these structures can be manipulated to generate coherent light in the UV-Blue region via SHG process or green emission via MPL process. The results show that these unique structures hold the potential to convert red input pulsed light into blue output pulsed light which is highly directional.
Date: May 2017
Creator: Butler, Sween J

"On the Precipice in the Dark": Maryland in the Secession Crisis, 1860-1861

Description: This dissertation is a study of the State of Maryland in the secession crisis of 1860-1861. Previous historians have emphasized economic, political, societal, and geographical considerations as the reasons Maryland remained loyal to the Union. However, not adequately considered is the manner in which Maryland understood and reacted to the secession of the Lower South. Historians have tended to portray Maryland's inaction as inevitable and reasonable. This study offers another reason for Maryland's inaction by placing the state in time and space, following where the sources lead, and allowing for contingency. No one in Maryland could have known that their state would not secede in 1860-61. Seeing the crisis through their eyes is instructive. It becomes clear that Maryland was a state on the brink of secession, but its resentment, suspicion, and anger toward the Lower South isolated it from the larger secession movement. Marylanders regarded the Lower South's rush to separate as precipitous, dangerous, and coercive to the Old Line State. A focus on a single state like Maryland allows a deeper, richer understanding of the dynamics, forces, and characteristics of the secession movement and the federal government's response to it. It cuts through the larger debates about the causes of secession and instead focuses on the manner in which secession was carried out, the intended effect of it, the actual effect it generated in the vitally important state of Maryland, and what it all says about the nature of internal divisions in the South at large.
Date: May 2017
Creator: Hamilton, Matthew Kyle