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On Mixed Variational Large Deformation Theories for Corrections of Classical von Kármán Theory of Thin Plates
(2018-05) Lassmann, James
For thin plates, linear deformation theory is only valid, when the plate deformation is on the order of the thickness of the plate. To ensure validity of results for larger deformations, geometrically non-linear strains must be used to properly reflect the behavior of the plates deformations. One of the earliest and most widely known non-linear plate theories is von Kármán thin plate theory, which was proposed by Theodore von Kármán in 1910. This thesis reexamines the classical von Kármán thin plate theory and seeks to re-formulate the governing equilibrium equations for thin plates undergoing large geometrically nonlinear deformations in terms of the plate displacements, using the Hu-Washizu mixed field variational statement. Additionally, other mixed field and single field variational statements are examined for the same purpose in order to determine any differences between them. Governing equilibrium equations yielded from each variational statement are compared to examine differences in the terms obtained. Those governing equilibrium equations will then be compared against existing formulations for the governing equilibrium equations for von Kármán thin plate theory, and their solutions found for the cases of statically loaded simply supported, statically loaded clamped plates, and simply supported free and forced vibrations to assess the validity of the governing equilibrium equations derived. Improvements to the formulation of thin plate theory allows for improvements to the design process of ship hulls, aircraft skins, and automobile bodies that incorporate thin plates. Improvements to accurate modeling of thin plates, could lead to reductions in the weight and cost of systems that use thin plates.
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Mindfulness for Science and Math Special Education Teachers: Perceived Value in Coping with Stress and Burnout
(2018-05) Cao, Carol A.
As education shifts to focus more on science, technology, engineering, and math (STEM) skills and 21st century skills, special education (SpEd) teachers are facing more challenges in the classroom to meet the needs of students with disabilities and to prepare their students for a global economy. These challenges add to the pressure and stress SpEd teachers encounter in the classroom. When the needs of teachers are not met, stress increases, leading to teacher burnout. Teacher burnout contributes to the high attrition rates and issues with teacher retention in SpEd. Without highly qualified teachers, the needs of students cannot be met. Schools and districts need to look at ways to help teachers cope with the challenges they face in the classroom. Mindfulness-based practices are one viable method to provide teachers with the tools and skills needed to alleviate feelings of burnout. This qualitative research study looked at five science and math special education (SpEd) teachers as they engaged in an eight-week long mindfulness-based practices training program. Data collected explored challenges participants face in science and math SpEd classroom that contribute to teacher burnout. In addition, data collected examined participants’ conceptual understanding of mindfulness and perceived value of a mindfulness-based practices training to address attrition and retention issues within SpEd. To better understand how participants perceived the value of mindfulness-based practices as viable tools and skills to cope with the challenges in the science and math SpEd classroom, to alleviate stress and burnout, and to build social and emotional competence (SEC), pre- and post-training interviews, reflective journals, and classroom observations. Findings suggested that participants developed a more comprehensive understanding of mindfulness and gained mindfulness skills (awareness, attention, autonomy, belonging and competency). These skills translated into the classroom and into participants’ personal lives. Perceived value in mindfulness-based practices related to the classroom included improved relationships with students, better management of student behaviors, improved classroom environment, better stress management, better ability to cope with the dimensions of burnout (emotional exhaustion, depersonalization, and lack of personal accomplishment), improved understanding of personal and students’ emotions, being less reactive, and connecting more with students. In their personal lives, participants noted that mindfulness-based practices positively affected their relationships with their children and help them stay more in the moment outside of the profession. However, participants expressed challenges with time and consistency with daily practice. Though all participants had overall positive experiences in the mindfulness-based practices training, they also noted the need for more trainings over a longer period of time and the need to start trainings at the beginning of the school year. Thus, it is important to take into consideration the needs of and recommendations from teachers in planning a future mindfulness-based practices training, as a viable means to address challenges in the classroom and teacher burnout.
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Three essays in corporate finance
(2018-05) Niu, Xu
This dissertation consists of three essays in corporate finance. The first essay examines whether founder family successions lower performance in large US firms. I find no significant drops, and often positive changes, in performance or value associated with founder family successions. The second essay studies the role of founder-CEOs and founder-families in IPOs. This paper shows that, in large US companies, founder-CEO and founder-family controlled firms experience about 10% more underpricing relative to non-founder firms during the IPO process. Moreover, this paper shows that the partial adjustment phenomenon is weaker for firms that are controlled by founder-CEOs at the time of IPOs, supporting Loughran and Ritter's (2002) prospect theory explanation on this effect. The third essay studies the relation between strategic voting and insider ownership. This paper outlines a model of strategic shareholder voting that allows outside shareholders to mitigate the influence of insiders. Consistent with the model, I find empirical support for strategic voting by outside shareholders and that strategic voting is more apparent when management-sponsored proposals are controversial or when other agency risks are greater.
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Texas High Plains American Viticulture Area, from vineyards to wines: natural microflora and its potential in wine identity
(2018-05) Bougreau, Matthias T.
Characterizing the specificities of wine-producing areas is necessary in the development of wine identity for international recognition, especially in younger wine-producing areas. The first section of this dissertation investigates the sensory properties of wines made from Cabernet Sauvignon and Tempranillo grapes grown in the Texas High Plains, the two red varieties of main interest in the area. Our objective was to understand the common specific sensory properties of Texas High Plains red wines and the similarities and differences between the two varieties, to gain a better idea of the identity of Texas High Plains wines. We demonstrated that sensory profiles of the two types of varietal wines were close and uneasy to discriminate. The importance of oak related characteristics was also highlighted. Taken together, the results of this study showed a potential lack of identity of wines from the Texas High Plains area due to the lack of consensus in the winemaking techniques used. Specificities of wine-producing areas are also a result of the influence of the many components of terroir. The dry semi-arid hot climate of Texas High Plains offers low disease pressure, an asset for viticulture, but also specific grapes and wines chemical composition, materialized by a low acidity content and high pH, which can be problematic during winemaking, potentially leading to microbial spoilage, sensory deviations and struggling alcoholic fermentation. Natural microbial populations present in the vineyard and specifically on the surface of grapes have been shown to be influenced by climate and soil, and themselves can have a consequent impact on chemical composition and sensory properties of wines, especially during natural fermentations. Microorganisms naturally present in the vineyards are thus an important component of terroir and local wine identity. Consequently, we evaluated the biodiversity of yeast present in the vineyard environment of Cabernet Sauvignon and Tempranillo grapes grown in the Texas High Plains area. The presence of species of enological interest was close to null with our recovery method and showed a low diversity on the surface of grapes. We conducted natural fermentation from Tempranillo grapes grown in the same Texas High Plains vineyard to select for minor species with enological interest, i.e. performing alcoholic fermentation. We found three species of enological interest, Saccharomyces cerevisiae, Hanseniaspora species and Lachancea thermotolerans. The presence of Lachancea thermotolerans, previously recovered from other hot areas, such as Spain on low acidity Tempranillo grapes, tends to suggest the presence of naturally adapted microorganisms for alcoholic fermentation of grapes with specific characteristics. Indeed, Lachancea thermotolerans has been previously characterized as an enological yeast producing L-lactic acid, thus acidifying the must and wines naturally. The use of Saccharomyces cerevisiae and Lachancea thermotolerans together for fermentation of low acidity grapes from the Texas High Plains area could promote a greater respect of terroir together with acidifying the must naturally, instead of resorting to chemical additions of tartaric acid, a process that can be responsible of unbalanced finished wines.
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Factors Impacting the Individual Adoption of Six Sigma Tools and Methodology
(2018-05) Mueller, Phillip S.
The process improvement methodology knows as six sigma is the application of statistical techniques and tools to reduce process variation and improve quality. The extensive set of tools and techniques of six sigma provides users with a structured methodology to bring processes under control. Companies like GE and Motorola have seen significant benefits from successfully implementing six sigma in terms of profitability and market value. However, not all companies that implement six sigma have seen such remarkable benefits. The cost of implementing six sigma can be significant and frequently companies have failed to achieve expected results or have failed to gain any benefits from the implementation of six sigma. The successful adoption of six sigma has been researched at the organizational level but not at the individual level. The successful adoption of six sigma in an organization is dependent, at least in part, to adoption six sigma at the individual level. A review of the existing literature indicates that there has been no research into individual adoption of six sigma. The primary purpose of this research was to increase the understanding of individual adoption of six sigma tools and methodology. In support of that purpose this research seeks to identify the following: 1) the factors that influence the adoption of six sigma tools and methodology at the individual level, 2) how an organization can measure the identified factors, 3) to what degree the identified factors influence the adoption of six sigma at the individual level, 4) any relationships between the factors that influence individual adoption of six sigma and 5) how an organization can use the findings from this study to improve the individual adoption of six sigma. This research used a single-site field study to empirically test and refine a theory of the factors impacting six sigma adoption at the individual level. Reaction to Training, Project Management and Project Infrastructure were found to be significant input factors for individual six sigma adoption with an R Square of 0.482, which indicates that about 48% of the variation in six sigma adoption is explained by the input factors. All of the identified input factors were found to have a positive relationship with individual six sigma adoption as well as positive correlations with each other. The findings of this research will be useful to practicing organizations which seek to improve individual six sigma adoptions as well as inform future six sigma adoption research.