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Investigation of 2195 and 2219 Post Weld Heat Treatments for Additive Friction Stir Lap Welds
Get PDFTo evaluate potential uses for friction stir welding in additive manufacturing, two separate parts were fabricated, one of 2195-T84 and the other 2219-T87, utilizing fixed pin techniques and additive lap welds. The parts were cut into samples, artificially aged and subjected to Rockwell hardness (HRB), Vickers hardness, micrographic photography, and metallographic imaging on both pre- and post- heat treatment. Additionally, tensile testing was performed on the heat-treated samples. A comparisons of test results showed a minimal increase in the yield strength of the 2195-T84 samples compared to as-welded tensile results obtained from a previous project. The ultimate tensile strength was reduced by approximately 16%. Further testing will be required to determine the nature of this reduction. No previous results were available for the as-welded 2219-T87, but UTS of the artificially aged samples was approximately 91% that of the parent material
Neurocorrelates of the Mirror Neuron System in Children with Chromosome 22q11.2 Deletion Syndrome
Get PDFActivation of brain regions that make up the mirror neuron system (MNS) is thought to reflect processing and perceiving behavior, action, and intentionality of other organisms. Sensing and perceiving motor behavior in others is an important component of understanding and participating in social interactions. Children with chromosome 22q11.2 deletion syndrome (22q11.2DS) are diagnosed with serious medical, cognitive, and socio-emotional symptoms. Atypical development and function of the MNS may underpin some aspects of socio-emotional impairment and autism spectrum disorder (ASD)-like symptomology reported. This study of the MNS investigates differences in activation in the operculum, sensorimotor areas, and basal ganglia (BG) in children with 22q11.2DS compared to typically-developing (TD) controls. Twenty-nine children (22q11.2DS: n=15; TD: n=16) between ages 7-16 viewed videos of a human hand manipulating various household objects during a functional magnetic resonance imaging (fMRI) scan. In Analysis 1, children with 22q11.2DS had less extensive brain activation than TD children in the operculum, sensorimotor areas, and BG. In Analysis 2, children with 22q11.2DS had the same results as Analysis 1 with the exception of sensorimotor areas not being highly active in either group. In both analyses, fMRI signal change from baseline to video did not differ significantly between groups. Processing efficiency in children with 22q11.2DS may be lower or more variable when compared to TD peers. This is the first study comparing children with 22q11.2DS to TD peers specifically looking at MNS activation within the operculum region to assess higher cognitive functioning, somatosensory cortex for sensory interpretation, and basal ganglia for gross motor activity. Future studies should compare brain activation between children with ASD and those with 22q11.2DS during an MNS task as the next step to further clarify the origin of ASD symptoms reported in this population
“More Challenging than I Expected but More Satisfying”: Exploring the Experiences of New Heads of Independent Schools and the Leadership Skills They Employ
Get PDFThis study examines leader behavior in an independent school setting. Specifically, this qualitative phenomenological study explores the lived experiences of new heads of schools in independent schools located in Louisiana, Texas, and Oklahoma and their conceptualization of the skills required for the headship. The study explores the knowledge and skills new heads say they use as leaders, how the knowledge and skills they developed in their careers prepared them for leadership, and the ways in which they feel they might have been better prepared for leadership. The study uses the skills-based model of leadership as its theoretical framework, and its methodological approach and discussion of findings are influenced by the framework’s three main areas: knowledge, social judgment skills, and problem-solving skills.
The study revealed three main types of knowledge relevant to independent school leader preparation: knowledge acquired through terminal degree or other formalized programs, practical knowledge acquired through professional experience, and institutional knowledge, i.e. knowledge unique to a head’s work in a specific school. The study also discusses three distinct ways in which new heads utilize social judgment skills: how they communicate, how they work with school constituents, and how they delegate work. The study suggests patience, deliberation, and listening are key factors in how new heads of school execute their problem-solving skills. The study also discusses other findings of note that are also relevant to the experiences of new heads of school. These include the feelings of loneliness and stress the participants felt as new heads as well as the personal and professional sources of support they sought because of those challenges. The study may be used to inform leader preparation programs oriented towards independent school leaders
Effect of Cell Wall Destruction on Anaerobic Digestion of Algal Biomass
Get PDFResearch was conducted using algal biomass obtained from the surface of a secondary clarifier at Bridge City Wastewater Treatment Plant and subsequently sent through an electrochemical (EC) batch reactor at various concentrations. The first objective was to achieve maximum cell wall destruction electrochemically using the EC batch reactor and determine the optimal detention time and voltage/current relationship at which this occurred. The second objective was to subject two algal mediums to anaerobic digestion: the algal medium without electrochemical disinfection and the algal medium after disinfection. Every three days, for 12 days, total solids were measured from each apparatus to determine if cell destruction increased, decreased or did not change the consumption rate of algae by anaerobic bacteria. The consumption rate of algae is directly proportional to the production of methane, which can be used as a source of biofuel
Mathematical Formulation of Fusion Energy Magnetohydrodynamics
Get PDFChapter 1 presents the basic principles of Controlled Thermonuclear Fusion, and the approaches to achieve nuclear fusion on Earth. Furthermore, the basic components of the Tokamak, the reactor which will house the fusion reaction, are analyzed. Finally, the chapter ends with a discussion on how the present thesis is related to the Controlled Thermonuclear Fusion. Chapter 2 introduces briefly the basic concepts of the Electromagnetic and Magnetohydrodynamic theories as well as MHD turbulence. Chapter 3 presents a first glance in OpenFOAM CFD library. Chapter 4 introduces the Orszag-Tang vortex flow, which is a benchmark test case for MHD numerical models. Also, the results obtained by the model developed in this thesis are presented and discussed. Chapter 5 describes an analytical solution method for the MHD natural convection in an internally heated horizontal shallow cavity. Also, a finite volume numerical model is presented for solving the aforementioned problem and properly validated. The results of the numerical model are compared with the analytical solutions for a range of Rayleigh and Hartmann numbers. Finally, conclusions based on this work are drawn and recommendations for future work are made
Growing Up In Downtown New Orleans
No full textAdama Evans interviews her father Harold Evans to elicit similarities and differences in their experiences growing up in New Orleans. Harold was raised in the 7th Ward during the 1950s where he graduated from Joseph S. Clark High School. After serving in the Air Force in Vietnam, he worked as a mental health counselor in the Desire Florida Counseling Center. Harold tells Adama about attending segregated schools, childhood games, foodways, music, the 7th ward community, and recreation at Lincoln Beach. Adama then reflects on her own experiences growing up in New Orleans during the 1990s focusing on recreation, her difficulties in high school, and the inequities of the New Orleans school system