Transient electrothermal simulation of power semiconductor devices

In this paper, a new thermal model based on the Fourier series solution of heat conduction equation has been introduced in detail. 1-D and 2-D Fourier series thermal models have been programmed in MATLAB/Simulink. Compared with the traditional finite-difference thermal model and equivalent RC thermal network, the new thermal model can provide high simulation speed with high accuracy, which has been proved to be more favorable in dynamic thermal characterization on power semiconductor switches. The complete electrothermal simulation models of insulated gate bipolar transistor (IGBT) and power diodes under inductive load switching condition have been successfully implemented in MATLAB/Simulink. The experimental results on IGBT and power diodes with clamped inductive load switching tests have verified the new electrothermal simulation model. The advantage of Fourier series thermal model over widely used equivalent RC thermal network in dynamic thermal characterization has also been validated by the measured junction temperature

The effect of intentionality on leadership development : a single-subject case study

The purpose of this single-subject case study was to examine the effect of intentionality on leadership development, employing the theoretical frameworks of Positive Organizational Scholarship and Multiple Realities. The two fundamental research questions that drove this study were: 1) What happened in the intentional leadership workshops that caused or did not cause a change in the anticipated behavior of informants? 2) What effect did the intentional leadership training workshops have on informants and their organizations? Data were collected according to the protocols of case study design, and were analyzed deductively

The Feasibility of Constructing Profiles of Native Americans from the People of Color Racial Identity Attitude Scale: A Brief Report

One hundred and fifty Lumbee Native American college students participated in an inves-tigation of the feasibility of constructing profiles of Native Americans from the People of Color Racial Identity Attitude Scale (PRIAS; Helms, 1995b). Findings suggest that Helms’s instrument may be feasible for constructing racial identity attitudes of Native Americans

Succeeding In School: The Online Reflections of Native American and Other Minority Students

This phenomenological study of students' online responses to the Succeeding in School program offers rare insight into how Native American and other minority students perceived and experienced their school environment. Students' strategies regarding behavior and attitude changes they would use to improve their success and counseling implications are discussed

The Racial Identity and Cultural Orientation of Lumbee American Indian High School Students

The uncertain and complex lineage of the Lumbee American Indian tribe has made the issue of identity of prime concern. The cultural identification, racial identification, bicultural competence, and perceived school environment for 103 Lumbee Indian high school students were examined in this study. Higher self-ratings on American Indian cultural competence and American Indian cultural identification than on White cultural competence and White cultural identification were found, and t-test comparisons revealed no gender differences on responses to the instruments. Analysis of variance was conducted to assess whether differences in perceived school environment could be attributed to cultural orientation. Rather than appearing assimilated, this generation of Lumbees tends to exhibit J. E. Helms's (1995b) Internalization identity status and an American Indian cultural orientation

A novel fluorescence based method of assessing subsurface damage in optical materials

Lapping and polishing are loose abrasive finishing processes that have been used to achieve critical surface parameters in optical materials for centuries. These processes remove material from the surface through a variety of mechanical and chemical interactions. These interactions influence not only the surface of the finished material, but also the subsurface, the region immediately beneath the surface. These processes may induce a damaged layer of cracks, voids and stressed material below the surface. This subsurface damage (SSD) can create optical aberrations due to diffraction, propagate to the surface, and reduce the laser induced damage threshold of the material. It is difficult to detect SSD, as these defects lie beneath the surface. Methods have been developed to detect SSD, but they can have notable limitations regarding sample size and material, preparation time, or they can be destructive in nature. The author tested a non-destructive method for assessing SSD that consisted of tagging the abrasive slurries used in loose abrasive finishing with quantum dots (nano-sized fluorescent particles). Subsequent detection of fluorescence on the processed surface is hypothesized to indicate SSD. Quantum dots present during the lapping process were retained in the glass sample through subsequent polishing and cleaning processes. The quantum dots were successfully imaged by both wide field and confocal fluorescence microscopy techniques. The detected fluorescence highlighted defects that were not observable with optical or interferometric microscopy. Analysis indicates that most dots are firmly embedded in the surface, however examination of confocal fluorescence scans beneath the surface did show incidences of quantum dots at depths up to 10 µm beneath the surface. The incidence of these deep features was less than 20% of the sites examined. Etching of the samples exhibiting fluorescence confirmed the presence of SSD and provided a conservative SSD depth estimate of 10 µm. These etching results confirm the hypothesis that quantum dots can tag SSD. Further testing demonstrated that for quantum dots to be embedded in the surface they must experience the dynamics of the lapping process, and that quantum dots can only tag brittle fracture sites. Quantum dots that were introduced to YAG samples during loose abrasive finishing were only retained on the surface and at levels consistent with simple exposure to quantum dots prior to cleaning, possibly highlighting surface defects that were not apparent with conventional microscopy. Subsequent etching of the YAG samples showed low levels of fracture in the subsurface region, indicating few suitable defects to house the quantum dots. In addition to the research above, an instrument was design and built to measure the axial and torque loads during loose abrasive finishing. Experiments with this measurement head showed expected increases in material removal rate and surface roughness with increased axial load. Results from these tests were also used to corroborate SSD depth estimates from glass samples finished with quantum dot laden slurries

Monitoring for success : implementing a proactive probation program for diverse, at-risk college students

"This study examined the impact of the University of North Carolina Greensboro's Strategies for Academic Success (SAS 100) program on the self-efficacy and academic achievement of students on academic probation. The Student Strategies for Success Survey, an instrument based upon Samejima's Graded Response Model, was used to collect data from 279 participants in a pre/post manner. The results showed a significant difference between participants' pre- and post-scores, indicating improved levels of Social Behavior, Academic Preparedness, Interdependence, Dedication, Self-knowledge, and Confidence. Qualitative data were collected through individual student interviews and document review to capture reasons why students performed poorly enough to be placed on academic probation and how the SAS 100 program facilitates the development of improved academic strategies. The factors that impact student retention were examined based on the collection of both quantitative and qualitative data. This study identified and described the characteristics of four unique cohort groups of students on academic probation. Both the quantitative and qualitative findings confirmed that the SAS 100 program had a positive impact by facilitating participants' development of improved academic strategies. Further, the Student Strategies for Success survey proved to be a reliable instrument in measuring the development of students on probation."--Abstract from author supplied metadata

Contemplation and mindfulness in education: between self and other in modernity

The following work identifies what the author contends are the two primary problems of modern behavior that inhibit the full development of human potential, namely: an over-confidence in reason, and a desire to influence other people for personal gain. These inhibiting behaviors are shown to originate specifically from features of the modern paradigm. To counter these problematic behaviors, the author suggests that contemplation can be an antidote. However, the author stresses that solely thinking of contemplation in its secular or spiritual categories is a limitation to its etymological roots and usage. Thus, the author introduces the term aneutral contemplation to move the reader past these restricting categories. The notion of aneutral contemplation is uniquely equipped to handle both modern behavioral limitations mentioned above, specifically by creating a space amicable to the contexts of silence and solitude. To clarify these contextual characteristics, examples are provided from the author's 44 days spent living and observing the monks of Mepkin Abbey. Finally, the project turns specifically to the process of education. The term transformative education is introduced to indicate a variety of education interested in promoting the contexts of silence and solitude. It is shown that only through the practice of mindfulness can this type of education be actualized. In other words, contemplation acts as the theoretical basis for the practical measures of mindfulness. The following project is meant to be a philosophical examination rather than a project of practical methods. I hope those who read this work will find the motivation to take off where this project concludes

Trilled song types are more salient than non-trilled song types in agonistic interactions between male song sparrows (Melospiza Melodia)

Most research on song complexity has mainly focused on repertoire size. However, the way various song structures within a repertoire function in male-male interactions is less well understood. In this study, I have explored the functional significance of songs containing a trilled syllable type shown to have a clear maximum physiological performance barrier versus songs that lack a trilled element. I performed playback experiments with 44 song sparrows on the campus of Western Carolina University in North Carolina. I found that males responded significantly more strongly to trilled than non-trilled songs, suggesting that song sparrows discriminate between song types within a repertoire. The results of this study suggest that male-male interactions may be important drivers for the evolution of complex repertoires in song sparrows. Future studies should focus on understanding how trilled and non-trilled songs function in male-male interactions

Can they row alone? practices that grow and support beginning principals

Beginning principals struggle with the complexity of the job, the limits of theirinstructional impact, the loneliness of leadership, and the existing culture’s resistance tochange. This is a problem in Henderson County Public Schools, in school systems acrossthe state of North Carolina, and nationwide. This problem negatively impacts beginningprincipals and their respective school communities because they struggle to navigateschool leadership transitions, to sustain district initiatives, and to experience consistentindividual growth. Students and parents have a right to expect competency from a schoolprincipal regardless of their lack of tenure, and districts must decide to be proactive inaccelerating the skills on new administrators. Effective mentoring programs can hastenthe competency of new school leaders.Given the absence of legislation, policy, and funding for beginning principal support inNorth Carolina, Henderson County Public Schools implemented a model designed togrow the leadership capacity of beginning principals in order that the impact of their service is maximized. The design of this purposeful intervention strategically matchesbeginning principals with mentors, while providing opportunities for professional growththrough self-assessment, reflection, and group learning.Using a Plan-Do-Study-Act (PDSA) cycle of improvement science, the scholarpractitionerscreated a scalable model for the mentoring of beginning principals.Experiencing the hire of six new principals in one school year, which markedapproximately 25% of the district’s school leadership, scholar-practitioners partneredwith the district to implement a structured support plan for these new administrators.Rather than leave their success to chance, Henderson County Public Schools recognizedand valued the importance of investing time and resources into leadership development.It is noteworthy that, following the period of initial research, the district has continuedwith and expanded the model of support. The results of this research inform not only thework of the partner school district, but also the practices of the current and futureleadership teams of North Carolina’s 115 systems, who guide over 2,400 principals asthey support more than 1.4 million students